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Results are presented on event-by-event fluctuations in transverse momentum of charged particles, produced at forward rapidities in p+p, C+C, Si+Si and Pb+Pb collisions at 158 AGeV. Three different characteristics are discussed: the average transverse momentum of the event, the Phi_pT fluctuation measure and two-particle transverse momentum correlations. In the kinematic region explored, the dynamical fluctuations are found to be small. However, a significant system size dependence of Phi_pT is observed, with the largest value measured in peripheral Pb+Pb interactions. The data are compared with predictions of several models. PACS numbers: 14.20.Jn, 13.75.Cs, 12.39.-x
Transverse momentum (pT) spectra of charged particles at mid-pseudorapidity in Xe-Xe collisions at sNN−−−√ = 5.44 TeV measured with the ALICE apparatus at the Large Hadron Collider are reported. The kinematic range 0.15<pT<50 GeV/c and |η|<0.8 is covered. Results are presented in nine classes of collision centrality in the 0-80% range. For comparison, a pp reference at the collision energy of s√ = 5.44 TeV is obtained by interpolating between existing \pp measurements at s√ = 5.02 and 7 TeV. The nuclear modification factors in central Xe-Xe collisions and Pb-Pb collisions at a similar center-of-mass energy of sNN−−−√ = 5.02 TeV, and in addition at 2.76 TeV, at analogous ranges of charged particle multiplicity density ⟨dNch/dη⟩ show a remarkable similarity at pT>10 GeV/c. The comparison of the measured RAA values in the two colliding systems could provide insight on the path length dependence of medium-induced parton energy loss. The centrality dependence of the ratio of the average transverse momentum ⟨pT⟩ in Xe-Xe collisions over Pb-Pb collision at s√ = 5.02 TeV is compared to hydrodynamical model calculations.
Transverse momentum (pT) spectra of charged particles at mid-pseudorapidity in Xe-Xe collisions at sNN−−−√ = 5.44 TeV measured with the ALICE apparatus at the Large Hadron Collider are reported. The kinematic range 0.15<pT<50 GeV/c and |η|<0.8 is covered. Results are presented in nine classes of collision centrality in the 0-80% range. For comparison, a pp reference at the collision energy of s√ = 5.44 TeV is obtained by interpolating between existing \pp measurements at s√ = 5.02 and 7 TeV. The nuclear modification factors in central Xe-Xe collisions and Pb-Pb collisions at a similar center-of-mass energy of sNN−−−√ = 5.02 TeV, and in addition at 2.76 TeV, at analogous ranges of charged particle multiplicity density ⟨dNch/dη⟩ show a remarkable similarity at pT>10 GeV/c. The centrality dependence of the ratio of the average transverse momentum ⟨pT⟩ in Xe-Xe collisions over Pb-Pb collision at s√ = 5.02 TeV is compared to hydrodynamical model calculations.
Recent results on transverse mass spectra of J/psi and psi prime mesons in central Pb+Pb collisions at 158 AGeV are considered. It is shown that those results support a hypothesis of statistical production of charmonia at hadronization and suggest the early thermal freeze-out of J/psi and psi prime mesons. Based on this approach the collective transverse velocity of hadronizing quark gluon plasma is estimated to be <v^H_T> \approx 0.2. Predictions for transverse mass spectra of hidden and open charm mesons at SPS and RHIC are discussed.
Transverse hadron spectra from proton-proton, proton-nucleus and nucleus-nucleus collisions from 2 AGeV to 21.3 ATeV are investigated within two independent transport approaches (HSD and UrQMD). For central Au+Au (Pb+Pb) collisions at energies above E lab ~ 5 AGeV, the measured K +- transverse mass spectra have a larger inverse slope parameter than expected from the default calculations. The additional pressure - as suggested by lattice QCD calculations at finite quark chemical potential mu q and temperature T - might be generated by strong interactions in the early pre-hadronic/partonic phase of central Au+Au (Pb+Pb) collisions. This is supported by a non-monotonic energy dependence of v2/pT in the present transport model.
The elliptic and triangular flow coefficients v2 and v3 of prompt D0, D+, and D∗+ mesons were measured at midrapidity (|y|<0.8) in Pb-Pb collisions at the centre-of-mass energy per nucleon pair of sNN−−−−√=5.02 TeV with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays in the transverse momentum interval 1<pT<36 GeV/c in central (0-10%) and semi-central (30-50%) collisions. Compared to pions, protons, and J/ψ mesons, the average D-meson vn harmonics are compatible within uncertainties with a mass hierarchy for pT≲3 GeV/c, and are similar to those of charged pions for higher pT. The coupling of the charm quark to the light quarks in the underlying medium is further investigated with the application of the event-shape engineering (ESE) technique to the D-meson v2 and pT-differential yields. The D-meson v2 is correlated with average bulk elliptic flow in both central and semi-central collisions. Within the current precision, the ratios of per-event D-meson yields in the ESE-selected and unbiased samples are found to be compatible with unity. All the measurements are found to be reasonably well described by theoretical calculations including the effects of charm-quark transport and the recombination of charm quarks with light quarks in a hydrodynamically expanding medium.
The elliptic and triangular flow coefficients v2 and v3 of prompt D0, D+, and D∗+ mesons were measured at midrapidity (|y|<0.8) in Pb-Pb collisions at the centre-of-mass energy per nucleon pair of sNN−−−−√=5.02 TeV with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays in the transverse momentum interval 1<pT<36 GeV/c in central (0-10%) and semi-central (30-50%) collisions. Compared to pions, protons, and J/ψ mesons, the average D-meson vn harmonics are found to follow a mass ordering for pT<3 GeV/c, and to be similar to those of charged pions for higher pT. The coupling of the charm quark to the light quarks in the underlying medium is further investigated with the application of the event-shape engineering (ESE) technique to the D-meson v2 and pT-differential yields. The D-meson v2 is correlated with average bulk elliptic flow in both central and semi-central collisions. Within the current precision, the ratios of per-event D-meson yields in the ESE-selected and unbiased samples are found to be compatible with unity. All the measurements are found to be reasonably well described by theoretical calculations including the effects of charm-quark transport and the recombination of charm quarks with light quarks in a hydrodynamically expanding medium.
Trapping black hole remnants
(2005)
Large extra dimensions lower the Planck scale to values soon accessible. The production of TeV mass black holes at the LHC is one of the most exciting predictions. However, the final phases of the black hole's evaporation are still unknown and there are strong indications that a black hole remnant can be left. Since a certain fraction of such objects would be electrically charged, we argue that they can be trapped. In this paper, we examine the occurrence of such charged black hole remnants. These trapped remnants are of high interest, as they could be used to closely investigate the evaporation characteristics. Due to the absence of background from the collision region and the controlled initial state, the signal would be very clear. This would allow to extract information about the late stages of the evaporation process with high precision.
Tree bark constitutes ideal habitat for microbial communities, because it is a stable substrate, rich in micro-niches. Bacteria, fungi, and terrestrial microalgae together form microbial communities, which in turn support more bark-associated organisms, such as mosses, lichens, and invertebrates, thus contributing to forest biodiversity. We have a limited understanding of the diversity and biotic interactions of the bark-associated microbiome, as investigations have mainly focussed on agriculturally relevant systems and on single taxonomic groups. Here we implemented a multi-kingdom metabarcoding approach to analyse diversity and community structure of the green algal, bacterial, and fungal components of the bark-associated microbial communities of beech, the most common broadleaved tree of Central European forests. We identified the most abundant taxa, hub taxa, and co-occurring taxa. We found that tree size (as a proxy for age) is an important driver of community assembly, suggesting that environmental filtering leads to less diverse fungal and algal communities over time. Conversely, forest management intensity had negligible effects on microbial communities on bark. Our study suggests the presence of undescribed, yet ecologically meaningful taxa, especially in the fungi, and highlights the importance of bark surfaces as a reservoir of microbial diversity. Our results constitute a first, essential step towards an integrated framework for understanding microbial community assembly processes on bark surfaces, an understudied habitat and neglected component of terrestrial biodiversity. Finally, we propose a cost-effective sampling strategy to study bark-associated microbial communities across large spatial or environmental scales.
Tree-local MCTAG with shared nodes : an analysis of word order variation in German and Korean
(2004)
Tree Adjoining Grammars (TAG) are known not to be powerful enough to deal with scrambling in free word order languages. The TAG-variants proposed so far in order to account for scrambling are not entirely satisfying. Therefore, an alternative extension of TAG is introduced based on the notion of node sharing. Considering data from German and Korean, it is shown that this TAG-extension can adequately analyse scrambling data, also in combination with extraposition and topicalization.
This paper profiles significant differences in syntactic distribution and differences in word class frequencies for two treebanks of spoken and written German: the TüBa-D/S, a treebank of transliterated spontaneous dialogs, and the TüBa-D/Z treebank of newspaper articles published in the German daily newspaper ´die tageszeitung´(taz). The approach can be used more generally as a means of distinguishing and classifying language corpora of different genres.
TriMem: a parallelized hybrid Monte Carlo software for efficient simulations of lipid membranes
(2022)
Lipid membranes are integral building blocks of living cells and perform a multitude of biological functions. Currently, molecular simulations of cellular-scale membrane structures at atomic resolution are nearly impossible, due to their size, complexity, and the large times-scales required. Instead, elastic membrane models are used to simulate membrane topologies and transitions between them, and to infer their properties and functions. Unfortunately, efficiently parallelized open-source simulation code to do so has been lacking. Here, we present TriMem, a parallel hybrid Monte Carlo simulation engine for triangulated lipid membranes. The kernels are efficiently coded in C++ and wrapped with Python for ease-of-use. The parallel implementation of the energy and gradient calculations and of Monte Carlo flip moves of edges in the triangulated membrane enable us to simulate also large and highly curved sub-cellular structures. For validation, we reproduce phase diagrams of vesicles with varying surface-to-volume ratios and area difference. The software can tackle a range of membrane remodelling processes on sub-cellular and cellular scales. Additionally, extensive documentation make the software accessible to the broad biophysics and computational cell biology communities.
In this article we provide a stack-theoretic framework to study the universal tropical Jacobian over the moduli space of tropical curves. We develop two approaches to the process of tropicalization of the universal compactified Jacobian over the moduli space of curves -- one from a logarithmic and the other from a non-Archimedean analytic point of view. The central result from both points of view is that the tropicalization of the universal compactified Jacobian is the universal tropical Jacobian and that the tropicalization maps in each of the two contexts are compatible with the tautological morphisms. In a sequel we will use the techniques developed here to provide explicit polyhedral models for the logarithmic Picard variety.
In this paper we present a parsing architecture that allows processing of different mildly context-sensitive formalisms, in particular Tree-Adjoining Grammar (TAG), Multi-Component Tree-Adjoining Grammar with Tree Tuples (TT-MCTAG) and simple Range Concatenation Grammar (RCG). Furthermore, for tree-based grammars, the parser computes not only syntactic analyses but also the corresponding semantic representations.
In this paper, we present an open-source parsing environment (Tübingen Linguistic Parsing Architecture, TuLiPA) which uses Range Concatenation Grammar (RCG) as a pivot formalism, thus opening the way to the parsing of several mildly context-sensitive formalisms. This environment currently supports tree-based grammars (namely Tree-Adjoining Grammars (TAG) and Multi-Component Tree-Adjoining Grammars with Tree Tuples (TT-MCTAG)) and allows computation not only of syntactic structures, but also of the corresponding semantic representations. It is used for the development of a tree-based grammar for German.
Moving in synchrony to external rhythmic stimuli is an elementary function that humans regularly engage in. It is termed “sensorimotor synchronization” and it is governed by two main parameters, the period and the phase of the movement with respect to the external rhythm. There has been an extensive body of research on the characteristics of these parameters, primarily once the movement synchronization has reached a steady-state level. Particular interest has been shown about how these parameters are corrected when there are deviations for the steady-state level. However, little is known about the initial “tuning-in” interval, when one aligns the movement to the external rhythm from rest. The current work investigates this “tuning-in” period for each of the four limbs and makes various novel contributions in the understanding of sensorimotor synchronization. The results suggest that phase and period alignment appear to be separate processes. Phase alignment involves limb-specific somatosensory memory in the order of minutes while period alignment has very limited memory usage. Phase alignment is the primary task but then the brain switches to period alignment where it spends most its resources. In overall this work suggests a central, cognitive role of period alignment and a peripheral, sensorimotor role of phase alignment.
Lattice strains of appropriate symmetry have served as an excellent tool to explore the interaction of superconductivity in the iron-based superconductors with nematic and stripe spin-density wave (SSDW) order, which are both closely tied to an orthorhombic distortion. In this work, we contribute to a broader understanding of the coupling of strain to superconductivity and competing normal-state orders by studying CaKFe4As4 under large, in-plane strains of B1g and B2g symmetry. In contrast to the majority of iron-based superconductors, pure CaKFe4As4 exhibits superconductivity with relatively high transition temperature of Tc∼35 K in proximity of a non-collinear, tetragonal, hedgehog spin-vortex crystal (SVC) order. Through experiments, we demonstrate an anisotropic in-plane strain response of Tc, which is reminiscent of the behavior of other pnictides with nematicity. However, our calculations suggest that in CaKFe4As4, this anisotropic response correlates with the one of the SVC fluctuations, highlighting the close interrelation of magnetism and high-Tc superconductivity. By suggesting moderate B2g strains as an effective parameter to change the stability of SVC and SSDW, we outline a pathway to a unified phase diagram of iron-based superconductivity.
Respiratory complex I in mitochondria and bacteria catalyzes the transfer of electrons from NADH to quinone (Q). The free energy available from the reaction is used to pump protons and to establish a membrane proton electrochemical gradient, which drives ATP synthesis. Even though several high-resolution structures of complex I have been resolved, how Q reduction is linked with proton pumping, remains unknown. Here, microsecond long molecular dynamics (MD) simulations were performed on Yarrowia lipolytica complex I structures where Q molecules have been resolved in the ~30 Å long Q tunnel. MD simulations of several different redox/protonation states of Q reveal the coupling between the Q dynamics and the restructuring of conserved loops and ion pairs. Oxidized quinone stabilizes towards the N2 FeS cluster, a binding mode not previously described in Yarrowia lipolytica complex I structures. On the other hand, reduced (and protonated) species tend to diffuse towards the Q binding sites closer to the tunnel entrance. Mechanistic and physiological relevance of these results are discussed.
The TOM complex is the main entry point for precursor proteins into mitochondria. Precursor proteins containing targeting sequences are recognized by the TOM complex and imported into the mitochondria. We have determined the structure of the TOM core complex from Neurospora crassa by single-particle cryoEM at 3.3 Å resolution, showing its interaction with a bound presequence at 4 Å resolution, and of the TOM holo complex including the Tom20 receptor at 6-7 Å resolution. TOM is a transmembrane complex consisting of two β-barrels, three receptor subunits and three short transmembrane subunits. Tom20 has a transmembrane helix and a receptor domain on the cytoplasmic side. We propose that Tom20 acts as a dynamic gatekeeper, guiding precursor proteins into the pores of the TOM complex. We analyze the interactions of Tom20 with other TOM subunits, present insights into the structure of the TOM holo complex, and suggest a translocation mechanism.
Olivo-cerebellar loops, where anatomical patches of the cerebellar cortex and inferior olive project one onto the other, form an anatomical unit of cerebellar computation. Here, we investigated how successive computational steps map onto olivo-cerebellar loops. Lobules IX-X of the cerebellar vermis, i.e. the nodulus and uvula, implement an internal model of the inner ear’s graviceptor, the otolith organs. We have previously identified two populations of Purkinje cells that participate in this computation: Tilt-selective cells transform egocentric rotation signals into allocentric tilt velocity signals, to track head motion relative to gravity, and translation-selective cells encode otolith prediction error. Here we show that, despite very distinct simple spike response properties, both types of Purkinje cells emit complex spikes that are proportional to sensory prediction error. This indicates that both cell populations comprise a single olivo-cerebellar loop, in which only translation-selective cells project to the inferior olive. We propose a neural network model where sensory prediction errors computed by translation-selective cells are used as a teaching signal for both populations, and demonstrate that this network can learn to implement an internal model of the otoliths.
We present measurements of two-particle differential number correlation functions R2 and transverse momentum correlation functions P2, obtained from p-Pb collisions at 5.02 TeV and Pb-Pb collisions at 2.76 TeV. The results are obtained using charged particles in the pseudorapidity range |η|< 1.0, and transverse momentum range 0.2<pT<2.0 GeV/c as a function of pair separation in pseudorapidity, |Δη|, azimuthal angle, Δφ, and for several charged-particle multiplicity classes. Measurements are carried out for like-sign and unlike-sign charged-particle pairs separately and combined to obtain charge-independent and charge-dependent correlation functions. We study the evolution of the width of the near-side peak of these correlation functions with collision centrality. Additionally, we study Fourier decompositions of the correlators in Δφ as a function of the pair separation |Δη|. Significant differences in the dependence of their harmonic coefficients on multiplicity classes are found. These differences can be exploited, in theoretical models, to obtain further insight into charged-particle production and transport in heavy-ion collisions. Moreover, an upper limit of non-flow contributions to flow coefficients vn measured in Pb-Pb collisions based on the relative strength of Fourier coefficients measured in p-Pb interactions is estimated.
We present measurements of two-particle differential number correlation functions R2 and transverse momentum correlation functions P2, obtained from p-Pb collisions at 5.02 TeV and Pb-Pb collisions at 2.76 TeV. The results are obtained using charged particles in the pseudorapidity range |η|< 1.0, and transverse momentum range 0.2<pT<2.0 GeV/c as a function of pair separation in pseudorapidity, |Δη|, azimuthal angle, Δφ, and for several charged-particle multiplicity classes. Measurements are carried out for like-sign and unlike-sign charged-particle pairs separately and combined to obtain charge-independent and charge-dependent correlation functions. We study the evolution of the width of the near-side peak of these correlation functions with collision centrality. Additionally, we study Fourier decompositions of the correlators in Δφ as a function of the pair separation |Δη|. Significant differences in the dependence of their harmonic coefficients on multiplicity classes are found. These differences can be exploited, in theoretical models, to obtain further insight into charged-particle production and transport in heavy-ion collisions. Moreover, an upper limit of non-flow contributions to flow coefficients vn measured in Pb-Pb collisions based on the relative strength of Fourier coefficients measured in p-Pb interactions is estimated.
Most sRNA biogenesis mechanisms involve either RNAseIII cleavage or ping-pong amplification by different Piwi proteins harboring slicer activity. Here, we follow the question why the mechanism of transgene-induced silencing in the ciliate Paramecium needs both Dicer activity and two Ptiwi proteins. This pathway involves primary siRNAs produced from non-translatable transgenes and secondary siRNAs from endogenous remote loci. Our data does not indicate any signatures from ping-pong amplification but Dicer cleavage of long dsRNA. We show that Ptiwi13 and 14 have different preferences for primary and secondary siRNAs but do not load them mutually exclusive. Both Piwis enrich for antisense RNAs and Ptiwi14 loaded siRNAs show a 5′-U signature. Both Ptiwis show in addition a general preference for Uridine-rich sRNAs along the entire sRNA length. Our data indicates both Ptiwis and 2’-O-methylation to contribute to strand selection of Dicer cleaved siRNAs. This unexpected function of two distinct vegetative Piwis extends the increasing knowledge of the diversity of Piwi functions in diverse silencing pathways. As both Ptiwis show differential subcellular localisation, Ptiwi13 in the cytoplasm and Ptiwi14 in the vegetative macronucleus, we conclude that cytosolic and nuclear silencing factors are necessary for efficient chromatin silencing.
Two-particle correlations on transverse rapidity in Au+Au collisions at √sNN = 200 GeV at STAR
(2022)
Two-particle correlation measurements projected onto two-dimensional, transverse rapidity coordinates (yT1,yT2), allow access to dynamical properties of the QCD medium produced in relativistic heavy-ion collisions that angular correlation measurements are not sensitive to. We report non-identified charged-particle correlations for Au + Au minimum-bias collisions at sNN−−−√ = 200 GeV taken by the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). Correlations are presented as 2D functions of transverse rapidity for like-sign, unlike-sign and all charged-particle pairs, as well as for particle pairs whose relative azimuthal angles lie on the near-side, the away-side, or at all relative azimuth. The correlations are constructed using charged particles with transverse momentum pT≥0.15 GeV/c, pseudorapidity from −1 to 1, and azimuthal angles from −π to π. The significant correlation structures that are observed evolve smoothly with collision centrality. The major correlation features include a saddle shape plus a broad peak with maximum near yT≈3, corresponding to pT≈ 1.5 GeV/c. The broad peak is observed in both like- and unlike-sign charge combinations and in near- and away-side relative azimuthal angles. The all-charge, all-azimuth correlation measurements are compared with the theoretical predictions of {\sc hijing} and {\sc epos}. The results indicate that the correlations for peripheral to mid-central collisions can be approximately described as a superposition of nucleon + nucleon collisions with minimal effects from the QCD medium. Strong medium effects are indicated in mid- to most-central collisions.
Two-particle transverse momentum differential correlators, recently measured in Pb--Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms and infer transport properties, such as the ratio of shear viscosity to entropy density, of the medium created in Pb-Pb collisions. The longitudinal long-range correlations and the large azimuthal anisotropy measured at low transverse momenta in small collision systems, namely pp and p-Pb, at LHC energies resemble manifestations of collective behaviour. This suggests that locally equilibrated matter may be produced in these small collision systems, similar to what is observed in Pb-Pb collisions. In this work, the same two-particle transverse momentum differential correlators are exploited in pp and p-Pb collisions at s√=7 TeV and sNN−−−√=5.02 TeV, respectively, to seek evidence for viscous effects. Specifically, the strength and shape of the correlators are studied as a function of the produced particle multiplicity to identify evidence for longitudinal broadening that might reveal the presence of viscous effects in these smaller systems. The measured correlators and their evolution from pp and p--Pb to Pb--Pb collisions are additionally compared to predictions from Monte Carlo event generators, and the potential presence of viscous effects is discussed.
Two-particle transverse momentum differential correlators, recently measured in Pb--Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms and infer transport properties, such as the ratio of shear viscosity to entropy density, of the medium created in Pb-Pb collisions. The longitudinal long-range correlations and the large azimuthal anisotropy measured at low transverse momenta in small collision systems, namely pp and p-Pb, at LHC energies resemble manifestations of collective behaviour. This suggests that locally equilibrated matter may be produced in these small collision systems, similar to what is observed in Pb-Pb collisions. In this work, the same two-particle transverse momentum differential correlators are exploited in pp and p-Pb collisions at √s=7 TeV and sNN−−−√=5.02 TeV, respectively, to seek evidence for viscous effects. Specifically, the strength and shape of the correlators are studied as a function of the produced particle multiplicity to identify evidence for longitudinal broadening that might reveal the presence of viscous effects in these smaller systems. The measured correlators and their evolution from pp and p--Pb to Pb--Pb collisions are additionally compared to predictions from Monte Carlo event generators, and the potential presence of viscous effects is discussed.
We report the results of the femtoscopic analysis of pairs of identical pions measured in p-Pb collisions at sNN−−−√=5.02 TeV. Femtoscopic radii are determined as a function of event multiplicity and pair momentum in three spatial dimensions. As in the pp collision system, the analysis is complicated by the presence of sizable background correlation structures in addition to the femtoscopic signal. The radii increase with event multiplicity and decrease with pair transverse momentum. When taken at comparable multiplicity, the radii measured in p-Pb collisions, at high multiplicity and low pair transverse momentum, are 10-20% higher than those observed in pp collisions but below those observed in A-A collisions. The results are compared to hydrodynamic predictions at large event multiplicity as well as discussed in the context of calculations based on gluon saturation.
We report the results of the femtoscopic analysis of pairs of identical pions measured in p-Pb collisions at sNN−−−√=5.02 TeV. Femtoscopic radii are determined as a function of event multiplicity and pair momentum in three spatial dimensions. As in the pp collision system, the analysis is complicated by the presence of sizable background correlation structures in addition to the femtoscopic signal. The radii increase with event multiplicity and decrease with pair transverse momentum. When taken at comparable multiplicity, the radii measured in p-Pb collisions, at high multiplicity and low pair transverse momentum, are 10-20% higher than those observed in pp collisions but below those observed in A-A collisions. The results are compared to hydrodynamic predictions at large event multiplicity as well as discussed in the context of calculations based on gluon saturation.
The two-proton correlation function at midrapidity from Pb+Pb central collisions at 158 AGeV has been measured by the NA49 experiment. The results are compared to model predictions from static thermal Gaussian proton source distributions and transport models RQMD and VENUS. An effective proton source size is determined by minimizing CHI-square/ndf between the correlation functions of the data and those calculated for the Gaussian sources, yielding 3.85 +-0.15(stat.) +0.60-0.25(syst.) fm. Both the RQMD and the VENUS model are consistent with the data within the error in the correlation peak region.
De novo fatty acid biosynthesis in humans is accomplished by a multidomain protein, the type I fatty acid synthase (FAS). Although ubiquitously expressed in all tissues, fatty acid synthesis is not essential in normal healthy cells due to sufficient supply with fatty acids by the diet. However, FAS is overexpressed in cancer cells and correlates with tumor malignancy, which makes FAS an attractive selective therapeutic target in tumorigenesis. Herein, we present a crystal structure of the condensing part of murine FAS, highly homologous to human FAS, with octanoyl moieties covalently bound to the transferase (MAT) and the condensation (KS) domain. The MAT domain binds the octanoyl moiety in a novel (unique) conformation, which reflects the pronounced conformational dynamics of the substrate binding site responsible for the MAT substrate promiscuity. In contrast, the KS binding pocket just subtly adapts to the octanoyl moiety upon substrate binding. Besides the rigid domain structure, we found a positive cooperative effect in the substrate binding of the KS domain by a comprehensive enzyme kinetic study. These structural and mechanistic findings contribute significantly to our understanding of the mode of action of FAS and may guide future rational inhibitor designs.
Chunk parsing has focused on the recognition of partial constituent structures at the level of individual chunks. Little attention has been paid to the question of how such partial analyses can be combined into larger structures for complete utterances. The TüSBL parser extends current chunk parsing techniques by a tree-construction component that extends partial chunk parses to complete tree structures including recursive phrase structure as well as function-argument structure. TüSBLs tree construction algorithm relies on techniques from memory-based learning that allow similarity-based classification of a given input structure relative to a pre-stored set of tree instances from a fully annotated treebank. A quantitative evaluation of TüSBL has been conducted using a semi-automatically constructed treebank of German that consists of appr. 67,000 fully annotated sentences. The basic PARSEVAL measures were used although they were developed for parsers that have as their main goal a complete analysis that spans the entire input.This runs counter to the basic philosophy underlying TüSBL, which has as its main goal robustness of partially analyzed structures.
We demonstrate ultra-sharp (≲10 nm) lateral p-n junctions in graphene using electronic transport, scanning tunneling microscopy, and first principles calculations. The p-n junction lies at the boundary between differentially-doped regions of a graphene sheet, where one side is intrinsic and the other is charge-doped by proximity to a flake of α-RuCl3 across a thin insulating barrier. We extract the p-n junction contribution to the device resistance to place bounds on the junction width. We achieve an ultra-sharp junction when the boundary between the intrinsic and doped regions is defined by a cleaved crystalline edge of α-RuCl3 located 2 nm from the graphene. Scanning tunneling spectroscopy in heterostructures of graphene, hexagonal boron nitride, and α-RuCl3 shows potential variations on a sub-10 nm length scale. First principles calculations reveal the charge-doping of graphene decays sharply over just nanometers from the edge of the α-RuCl3 flake.
We demonstrate ultra-sharp (≲10 nm) lateral p-n junctions in graphene using electronic transport, scanning tunneling microscopy, and first principles calculations. The p-n junction lies at the boundary between differentially-doped regions of a graphene sheet, where one side is intrinsic and the other is charge-doped by proximity to a flake of α-RuCl3 across a thin insulating barrier. We extract the p-n junction contribution to the device resistance to place bounds on the junction width. We achieve an ultra-sharp junction when the boundary between the intrinsic and doped regions is defined by a cleaved crystalline edge of α-RuCl3 located 2 nm from the graphene. Scanning tunneling spectroscopy in heterostructures of graphene, hexagonal boron nitride, and α-RuCl3 shows potential variations on a sub-10 nm length scale. First principles calculations reveal the charge-doping of graphene decays sharply over just nanometers from the edge of the α-RuCl3 flake.
Nous présentons ici différents algorithmes d’analyse pour grammaires à concaténation d’intervalles (Range Concatenation Grammar, RCG), dont un nouvel algorithme de type Earley, dans le paradigme de l’analyse déductive. Notre travail est motivé par l’intérêt porté récemment à ce type de grammaire, et comble un manque dans la littérature existante.
This article reports measurements characterizing the Underlying Event (UE) associated with hard scatterings at midrapidity in pp collisions at s√=13 TeV. The hard scatterings are identified by the leading particle, the charged particle with the highest transverse momentum (pleadingT) in the event. Charged-particle number and summed transverse-momentum densities are measured in different azimuthal regions defined with respect to the leading particle direction: Toward, Transverse, and Away. The Toward and Away regions contain the fragmentation products of the hard scatterings in addition to the UE contribution, whereas particles in the Transverse region are expected to originate predominantly from the UE. The study is performed as a function of pleadingT with three different pT thresholds for the associated particles, pminT> 0.15, 0.5, and 1.0 GeV/c. The charged-particle density in the Transverse region rises steeply for low values of pleadingT and reaches a plateau. The results confirm the trend that the charged-particle density in the Transverse region shows a stronger increase with s√ than the inclusive charged-particle density at midrapidity. The UE activity is increased by approximately 20% when going from 7 to 13 TeV. The plateau in the Transverse region (5<pleadingT< 40 GeV/c ) is further characterized by the probability distribution of its charged-particle multiplicity normalized to its average value (relative transverse activity, RT) and the mean transverse momentum as a function of RT. Experimental results are compared to model calculations using PYTHIA 8 and EPOS LHC. The overall agreement between models and data is within 30%. These measurements provide new insights on the interplay between hard scatterings and the associated UE in pp collisions.
This article reports measurements characterizing the Underlying Event (UE) associated with hard scatterings at midrapidity (|η|<0.8) in pp collisions at s√ = 13 TeV. The hard scatterings are identified by the leading particle, the charged particle with the highest transverse momentum (pleadingT) in the event. Charged-particle numbers and summed transverse-momentum densities are measured in different azimuthal regions defined with respect to the leading particle direction: Toward, Transverse, and Away. The Toward and Away regions contain the fragmentation products of the hard scatterings in addition to the UE contribution, whereas particles in the Transverse region are expected to originate predominantly from the UE. The study is performed as a function of pleadingT with three different pT thresholds for the associated particles, ptrackT> 0.15, 0.5, and 1.0 GeV/c. The charged-particle density in the Transverse region rises steeply for low values of pleadingT and reaches a plateau. The results confirm the trend observed at lower collision energies that the charged-particle density in the Transverse region shows a stronger increase with s√ than the inclusive charged-particle density at midrapidity. The plateau in the Transverse region (5<pleadingT<40 GeV/c) is further characterized by the probability distribution of its charged-particle multiplicity normalized to its average value (relative transverse activity, RT) and the mean transverse momentum as a function of RT. Experimental results are compared to model calculations obtained using PYTHIA 8 and EPOS LHC. The overall agreement between models and data is within 30%. These measurements provide new insights on the interplay between hard scatterings and the associated UE in pp collisions.
We report about the properties of the underlying event measured with ALICE at the LHC in pp and p−Pb collisions at sNN−−−√=5.02 TeV. The event activity, quantified by charged-particle number and summed-pT densities, is measured as a function of the leading-particle transverse momentum (ptrigT). These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different pT thresholds (0.15, 0.5, and 1 GeV/c) at mid-pseudorapidity (|η|<0.8). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p−Pb collisions, namely, a steep increase with ptrigT for low ptrigT, followed by a saturation at ptrigT≈5 GeV/c. The results from pp collisions are compared with existing measurements at other centre-of-mass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contribution measured in the transverse region. The remaining jet-like particle densities are consistent in pp and p−Pb collisions for ptrigT>10 GeV/c, whereas for lower ptrigT values the event activity is slightly higher in p−Pb than in pp collisions. The measurements are compared with predictions from the PYTHIA 8 and EPOS LHC Monte Carlo event generators.
We report about the properties of the underlying event measured with ALICE at the LHC in pp and p−Pb collisions at sNN−−−√=5.02 TeV. The event activity, quantified by charged-particle number and summed-pT densities, is measured as a function of the leading-particle transverse momentum (ptrigT). These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different pT thresholds (0.15, 0.5, and 1 GeV/c) at mid-pseudorapidity (|η|<0.8). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p−Pb collisions, namely, a steep increase with ptrigT for low ptrigT, followed by a saturation at ptrigT≈5 GeV/c. The results from pp collisions are compared with existing measurements at other centre-of-mass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contribution measured in the transverse region. The remaining jet-like particle densities are consistent in pp and p−Pb collisions for ptrigT>10 GeV/c, whereas for lower ptrigT values the event activity is slightly higher in p−Pb than in pp collisions. The measurements are compared with predictions from the PYTHIA 8 and EPOS LHC Monte Carlo event generators.
Motivated by the on-going discussion on the nature of magnetism in the quantum Ising chain CoNb2O6, we present a first-principles-based analysis of its exchange interactions by applying an \textit{ab initio} approach with additional modelling that accounts for various drawbacks of a purely density functional theory ansatz. With this method we are able to extract and understand the origin of the magnetic couplings under inclusion of all symmetry-allowed terms, and to resolve the conflicting model descriptions in CoNb2O6. We find that the twisted Kitaev chain and the transverse-field ferromagnetic Ising chain views are mutually compatible, although additional off-diagonal exchanges are necessary to provide a complete picture. We show that the dominant exchange interaction is a ligand-centered exchange process - involving the eg electrons -, which is rendered anisotropic by the low-symmetry crystal fields environments in CoNb2O6, giving rise to the dominant Ising exchange, while the smaller bond-dependent anisotropies are found to originate from d−d kinetic exchange processes involving the t2g electrons. We demonstrate the validity of our approach by comparing the predictions of the obtained low-energy model to measured THz and inelastic neutron scattering spectra.
Human behaviour is inextricably linked to the interaction of emotion and cognition. For decades, emotion and cognition were perceived as separable processes, yet with mutual interactions. Recently, this differen-tiation has been challenged by more integrative approaches, but without addressing the exact neurophysiological basis of their interaction. Here, we aimed to uncover neurophysiological mechanisms of emotion-cognition interaction. We used an emotional Flanker task paired with EEG/FEM beamforming in a large cohort (N=121) of healthy human participants, obtaining high temporal and fMRI-equivalent spatial resolution. Spatially, emotion and cognition processing overlapped in the right inferior frontal gyrus (rIFG), specifically in pars triangularis. Temporally, emotion and cognition processing overlapped during the transition from emotional to cognitive processing, with a stronger interaction in β-band power leading to worse behavioral performance. Despite functionally segregated subdivisions in rIFG, frequency-specific information flowed extensively within IFG and top-down to visual areas (V2, Precuneus) – explaining the behavioral interference effect. Thus, for the first time we here show the neural mechanisms of emotion-cognition interaction in space, time, frequency and information transfer with high temporal and spatial resolution, revealing a central role for β-band activity in rIFG. Our results support the idea that rIFG plays a broad role in both inhibitory control and emotional interference inhibition as it is a site of convergence in both processes. Furthermore, our results have potential clinical implications for understanding dysfunctional emotion-cognition interaction and emotional interference inhibition in psychiatric disor-ders, e.g. major depression and substance use disorder, in which patients have difficulties in regulating emotions and executing inhibitory control.
During animal development, it is crucial that cells can sense and adapt to mechanical forces from their environment. Ultimately, these forces are transduced through the actomyosin cortex. How the cortex can simultaneously respond to and create forces during cytokinesis is not well understood. Here we show that under mechanical stress, cortical actomyosin flow switches its polarization during cytokinesis in the C. elegans embryo. In unstressed embryos, longitudinal cortical flows contribute to contractile ring formation, while rotational cortical flow is additionally induced in uniaxially loaded embryos. Rotational cortical flow is required for the redistribution of the actomyosin cortex in loaded embryos. Rupture of longitudinally aligned cortical fibers during cortex rotation releases tension, initiates orthogonal longitudinal flow and thereby contributes to furrowing in loaded embryos. A targeted screen for factors required for rotational flow revealed that actomyosin regulators involved in RhoA regulation, cortical polarity and chirality are all required for rotational flow and become essential for cytokinesis under mechanical stress. In sum, our findings extend the current framework of mechanical stress response during cell division and show scaling of orthogonal cortical flows to the amount of mechanical stress.
Uniform sampling from the set G(d) of graphs with a given degree-sequence d=(d1,…,dn)∈Nn is a classical problem in the study of random graphs. We consider an analogue for temporal graphs in which the edges are labeled with integer timestamps. The input to this generation problem is a tuple D=(d,T)∈Nn×N>0 and the task is to output a uniform random sample from the set G(D) of temporal graphs with degree-sequence d and timestamps in the interval [1,T]. By allowing repeated edges with distinct timestamps, G(D) can be non-empty even if G(d) is, and as a consequence, existing algorithms are difficult to apply.
We describe an algorithm for this generation problem which runs in expected time O(M) if Δ2+ϵ=O(M) for some constant ϵ>0 and T−Δ=Ω(T) where M=∑idi and Δ=maxidi. Our algorithm applies the switching method of McKay and Wormald [1] to temporal graphs: we first generate a random temporal multigraph and then remove self-loops and duplicated edges with switching operations which rewire the edges in a degree-preserving manner.
Uniform sampling from the set G(d) of graphs with a given degree-sequence d=(d1,…,dn)∈Nn is a classical problem in the study of random graphs. We consider an analogue for temporal graphs in which the edges are labeled with integer timestamps. The input to this generation problem is a tuple D=(d,T)∈Nn×N>0 and the task is to output a uniform random sample from the set G(D) of temporal graphs with degree-sequence d and timestamps in the interval [1,T]. By allowing repeated edges with distinct timestamps, G(D) can be non-empty even if G(d) is, and as a consequence, existing algorithms are difficult to apply.
We describe an algorithm for this generation problem which runs in expected time O(M) if Δ2+ϵ=O(M) for some constant ϵ>0 and T−Δ=Ω(T) where M=∑idi and Δ=maxidi. Our algorithm applies the switching method of McKay and Wormald [1] to temporal graphs: we first generate a random temporal multigraph and then remove self-loops and duplicated edges with switching operations which rewire the edges in a degree-preserving manner.
Recently, significant advances have been made by identifying the levels of synchronicity of the underlying dynamics of a given brain state. This research has demonstrated that unconscious dynamics tend to be more synchronous than those found in conscious states, which are more asynchronous. Here we go beyond this dichotomy to demonstrate that the different brain states are always underpinned by spatiotemporal chaos but with dissociable turbulent dynamics. We investigated human neuroimaging data from different brain states (resting state, meditation, deep sleep, and disorders of consciousness after coma) and were able to distinguish between them using complementary model-free and model-based measures of turbulent information transmission. Our model-free approach used recent advances describing a measure of information cascade across spatial scales using tools from turbulence theory. Complementarily, our model-based approach used exhaustive in silico perturbations of whole-brain models fitted to the empirical neuroimaging data, which allowed us to study the information encoding capabilities of the brain states. Overall, the current framework demonstrates that different levels of turbulent dynamics are fundamental for describing and differentiating between brain states.
Autophagosome biogenesis requires a localized perturbation of lipid membrane dynamics and a unique protein-lipid conjugate. Autophagy-related (ATG) proteins catalyze this biogenesis on cellular membranes, but the underlying molecular mechanism remains unclear. Focusing on the final step of the protein-lipid conjugation reaction, ATG8/LC3 lipidation, we show how membrane association of the conjugation machinery is organized and fine-tuned at the atomistic level. Amphipathic α-helices in ATG3 proteins (AHATG3) are found to have low hydrophobicity and to be less bulky. Molecular dynamics simulations reveal that AHATG3 regulates the dynamics and accessibility of the thioester bond of the ATG3∼LC3 conjugate to lipids, allowing covalent lipidation of LC3. Live cell imaging shows that the transient membrane association of ATG3 with autophagic membranes is governed by the less bulky- hydrophobic feature of AHATG3. Collectively, the unique properties of AHATG3 facilitate protein- lipid bilayer association leading to the remodeling of the lipid bilayer required for the formation of autophagosomes.
We show that an unambiguous way of determining the universal limiting fragmentation region is to consider the derivative (d 2 n / d eta 2) of the pseudo-rapidity distribution per participant pair. In addition, we find that the transition region between the fragmentation and the central plateau regions exhibits a second kind of universal behavior that is only apparent in d 2 n / d eta 2. The sqrt s dependence of the height of the central plateau (d n / d eta) eta=0 and the total charged particle multiplicity n total critically depend on the behavior of this universal transition curve. Analyzing available RHIC data, we show that (dn/d eta) eta=0 can be bounded by ln 2 s and n total can be bounded by ln 3 s. We also show that the deuteron-gold data from RHIC has the exactly same features as the gold-gold data indicating that these universal behaviors are a feature of the initial state parton-nucleus interactions and not a consequence of final state interactions. Predictions for LHC energy are also given.
We propose a new security measure for commitment protocols, called Universally Composable (UC) Commitment. The measure guarantees that commitment protocols behave like an \ideal commitment service," even when concurrently composed with an arbitrary set of protocols. This is a strong guarantee: it implies that security is maintained even when an unbounded number of copies of the scheme are running concurrently, it implies non-malleability (not only with respect to other copies of the same protocol but even with respect to other protocols), it provides resilience to selective decommitment, and more. Unfortunately two-party uc commitment protocols do not exist in the plain model. However, we construct two-party uc commitment protocols, based on general complexity assumptions, in the common reference string model where all parties have access to a common string taken from a predetermined distribution. The protocols are non-interactive, in the sense that both the commitment and the opening phases consist of a single message from the committer to the receiver.
Visual scene perception is mediated by a set of cortical regions that respond preferentially to images of scenes, including the occipital place area (OPA) and parahippocampal place area (PPA). However, the differential contribution of OPA and PPA to scene perception remains an open research question. In this study, we take a deep neural network (DNN)-based computational approach to investigate the differences in OPA and PPA function. In a first step we search for a computational model that predicts fMRI responses to scenes in OPA and PPA well. We find that DNNs trained to predict scene components (e.g., wall, ceiling, floor) explain higher variance uniquely in OPA and PPA than a DNN trained to predict scene category (e.g., bathroom, kitchen, office). This result is robust across several DNN architectures. On this basis, we then determine whether particular scene components predicted by DNNs differentially account for unique variance in OPA and PPA. We find that variance in OPA responses uniquely explained by the navigation-related floor component is higher compared to the variance explained by the wall and ceiling components. In contrast, PPA responses are better explained by the combination of wall and floor, that is scene components that together contain the structure and texture of the scene. This differential sensitivity to scene components suggests differential functions of OPA and PPA in scene processing. Moreover, our results further highlight the potential of the proposed computational approach as a general tool in the investigation of the neural basis of human scene perception.
Cross-frequency coupling (CFC) has been proposed to coordinate neural dynamics across spatial and temporal scales. Despite its potential relevance for understanding healthy and pathological brain function, the standard CFC analysis and physiological interpretation come with fundamental problems. For example, apparent CFC can appear because of spectral correlations due to common non-stationarities that may arise in the total absence of interactions between neural frequency components. To provide a road map towards an improved mechanistic understanding of CFC, we organize the available and potential novel statistical/modeling approaches according to their biophysical interpretability. While we do not provide solutions for all the problems described, we provide a list of practical recommendations to avoid common errors and to enhance the interpretability of CFC analysis.
Untangling the cell immune response dynamic for severe and critical cases of SARS-CoV-2 infection
(2021)
COVID-19 is a global pandemic leading high death tolls worldwide day by day. Clinical evidence suggests that COVID-19 patients can be classified as non-severe, severe and critical cases. In particular, studies have highlighted the relationship between the lymphopenia and the severity of the illness, where CD8+ T cells have the lowest levels in critical cases. In this work, we aim to elucidate the key parameters that define the course of the disease deviating from severe to critical case. To this end, several mathematical models are proposed to represent the dynamic of the immune response in patients with SARS-CoV-2 infection. The best model had a good fit to reported experimental data, and in accordance with values found in the literature. Our results suggest that a rapid proliferation of CD8+ T cells is decisive in the severity of the disease.
Anhand eines Datensatzes von 1.708 Vegetationsaufnahmen aus 154 bayerischen Naturwaldreservaten wurde die realisierte ökologische Nische von 25 Baumarten hinsichtlich Lichtbedarf bzw. Schattentoleranz untersucht. Für jede Baumart wurde die Stetigkeit des Vorkommens in Baumschicht und Verjüngung berechnet. Für jede Aufnahme wurde die dem Bestandesunterwuchs zur Verfügung stehende Lichtmenge durch Berechnung des mittleren ungewichteten Licht-Zeigerwertes (mL) aller vorkommenden Arten (ohne Baumschicht) auf einer Relativskala geschätzt. Für jede 0,5-Einheiten-Stufe von mL wurde die Präferenz jeder Baumart, getrennt nach Baum- (> 5m) und Verjüngungsschicht (< 5m), als Differenz zwischen relativer Häufigkeit der jeweiligen Art und der relativen Häufigkeit aller Aufnahmen in der mL-Stufe im gesamten Datensatz berechnet. Die Präferenzprofile von Baumschicht und Verjüngungsschicht bildeten die Grundlage einer numerischen Klassifikation von 6 lichtökologischen Nischen typen. Diese Typen werden hinsichtlich ihrer Bindung an bestimmte Entwicklungsphasen und Strukturen der natürlichen Walddynamik diskutiert, mit geläufigen Einteilungen der Baumarten verglichen und im Hinblick auf eine Prognose des Verhaltens unter sich ändernden Umweltbedingungen ausgewertet. – Während sich Edellaubbäume des Tilio-Acerion in den Reservaten sehr ähnlich wie Fagus und Abies verhalten, bilden die Baumarten der Eichenmischwälder eine lichtökologische Gruppe mit rückläufiger Verjüngungstendenz. Unter den übrigen Halbschattbaumarten hebt sich eine Gruppe heraus, welche sich in geschlossenen Beständen vorausverjüngt und nach Störung in die Baumschicht vordringt. Pionierbaumarten bleiben in Naturwaldreservaten weitestgehend auf Sonderstandorte, wo ihre Verjüngung viel Licht vorfindet, beschränkt.
Properties of dense quark matter in and out of chemical equilibrium are studied within the SU(3) Nambu Jona-Lasinio model. In addition to the 4 fermion scalar and vector terms the model includes also the 6 fermion flavour mixing interaction. First we study a novel form of deconfined matter, meso-matter, which is composed of equal number of quarks and antiquarks. It can be thought of as a strongly compressed meson gas where mesons are melted into their elementary constituents, quarks and antiquarks. Strongly bound states in this quark antiquark matter are predicted for all flavour combinations of qq pairs. The maximum binding energy reaches up to 180 MeV per qq pair for mixtures with about 70% of strange (s¯s) pairs. Equilibrated baryon rich quark matter with various flavour compositions is also studied. In this case only shallow bound states appear in systems with a significant admixture(about 40%) of strange quarks (strangelets). Their binding energies are quite sensitive to the relative strengths of scalar and vector interactions. The common property of all these bound states is that they appear at high particle densities when the chiral symmetry is nearly restored. Thermal properties of meso-matter as well as chemically equilibrated strange quark matter are also investigated. Possible decay modes of these bound states are discussed.
The human visual cortex enables visual perception through a cascade of hierarchical computations in cortical regions with distinct functionalities. Here, we introduce an AI-driven approach to discover the functional mapping of the visual cortex. We related human brain responses to scene images measured with functional MRI (fMRI) systematically to a diverse set of deep neural networks (DNNs) optimized to perform different scene perception tasks. We found a structured mapping between DNN tasks and brain regions along the ventral and dorsal visual streams. Low-level visual tasks mapped onto early brain regions, 3-dimensional scene perception tasks mapped onto the dorsal stream, and semantic tasks mapped onto the ventral stream. This mapping was of high fidelity, with more than 60% of the explainable variance in nine key regions being explained. Together, our results provide a novel functional mapping of the human visual cortex and demonstrate the power of the computational approach.
One of the key challenges for nuclear physics today is to understand from first principles the effective interaction between hadrons with different quark content. First successes have been achieved using techniques that solve the dynamics of quarks and gluons on discrete space-time lattices. Experimentally, the dynamics of the strong interaction have been studied by scattering hadrons off each other. Such scattering experiments are difficult or impossible for unstable hadrons and so high-quality measurements exist only for hadrons containing up and down quarks. Here we demonstrate that measuring correlations in the momentum space between hadron pairs produced in ultrarelativistic proton-proton collisions at the CERN Large Hadron Collider (LHC) provides a precise method with which to obtain the missing information on the interaction dynamics between any pair of unstable hadrons. Specifically, we discuss the case of the interaction of baryons containing strange quarks (hyperons). We demonstrate how, using precision measurements of p-omega baryon correlations, the effect of the strong interaction for this hadron-hadron pair can be studied with precision similar to, and compared with, predictions from lattice calculations. The large number of hyperons identified in proton-proton collisions at the LHC, together with an accurate modelling of the small (approximately one femtometre) inter-particle distance and exact predictions for the correlation functions, enables a detailed determination of the short-range part of the nucleon-hyperon interaction.
Results are presented from a search for the decays D0 -> K min pi plus and D0 bar -> K plus pi min in a sample of 3.8x10^6 central Pb-Pb events collected with a beam energy of 158A GeV by NA49 at the CERN SPS. No signal is observed. An upper limit on D0 production is derived and compared to predictions from several models.
UrQMD at RHIC energies
(1999)
We adopt Markert and Nissim (2005)’s approach of using the World Wide Web to resolve cases of coreferent bridging for German and discuss the strength and weaknesses of this approach. As the general approach of using surface patterns to get information on ontological relations between lexical items has only been tried on English, it is also interesting to see whether the approach works for German as well as it does for English and what differences between these languages need to be accounted for. We also present a novel approach for combining several patterns that yields an ensemble that outperforms the best-performing single patterns in terms of both precision and recall.
Oncogenic transformation of lung epithelial cells is a multi-step process, frequently starting with the inactivation of tumor suppressors and subsequent activating mutations in proto-oncogenes, such as members of the PI3K or MAPK family. Cells undergoing transformation have to adjust to changes, such as metabolic requirements. This is achieved, in part, by modulating the protein abundance of transcription factors, which manifest these adjustments. Here, we report that the deubiquitylase USP28 enables oncogenic reprogramming by regulating the protein abundance of proto-oncogenes, such as c-JUN, c-MYC, NOTCH and ΔNP63, at early stages of malignant transformation. USP28 is increased in cancer compared to normal cells due to a feed-forward loop, driven by increased amounts of oncogenic transcription factors, such as c-MYC and c-JUN. Irrespective of oncogenic driver, interference with USP28 abundance or activity suppresses growth and survival of transformed lung cells. Furthermore, inhibition of USP28 via a small molecule inhibitor reset the proteome of transformed cells towards a ‘pre-malignant’ state, and its inhibition cooperated with clinically established compounds used to target EGFRL858R, BRAFV600E or PI3KH1047R driven tumor cells. Targeting USP28 protein abundance already at an early stage via inhibition of its activity therefore is a feasible strategy for the treatment of early stage lung tumours and the observed synergism with current standard of care inhibitors holds the potential for improved targeting of established tumors.
The establishment and maintenance of protected areas (PAs) is viewed as a key action in delivering post-2020 biodiversity targets. PAs often need to meet multiple objectives, ranging from biodiversity protection to ecosystem service provision and climate change mitigation, but available land and conservation funding is limited. Therefore, optimizing resources by selecting the most beneficial PAs is vital. Here, we advocate for a flexible and transparent approach to selecting protected areas based on multiple objectives, and illustrate this with a decision support tool on a global scale. The tool allows weighting and prioritization of different conservation objectives according to user-specified preferences, as well as real-time comparison of the selected areas that result from such different priorities. We apply the tool across 1347 terrestrial PAs and highlight frequent trade-offs among different objectives, e.g., between species protection and ecosystem integrity. Outputs indicate that decision makers frequently face trade-offs among conflicting objectives. Nevertheless, we show that transparent decision-support tools can reveal synergies and trade-offs associated with PA selection, thereby helping to illuminate and resolve land-use conflicts embedded in divergent societal and political demands and values.
In this paper, we argue that difficulties in the definition of coreference itself contribute to lower inter-annotator agreement in certain cases. Data from a large referentially annotated corpus serves to corroborate this point, using a quantitative investigation to assess which effects or problems are likely to be the most prominent. Several examples where such problems occur are discussed in more detail, and we then propose a generalisation of Poesio, Reyle and Stevenson’s Justified Sloppiness Hypothesis to provide a unified model for these cases of disagreement and argue that a deeper understanding of the phenomena involved allows to tackle problematic cases in a more principled fashion than would be possible using only pre-theoretic intuitions.
We present results of hard X-ray angle-resolved photoemission spectroscopy and photoemission diffraction measurements performed on high-quality single crystals of the valence transition compound EuPd2Si2 for temperatures 25~K ≤ T ≤ 300~K. At low temperatures we observe a Eu 4f valence v=2.5, % occupation number n=6.5, which decreases to v=2.1 for temperatures above the valence transition around TV≈160~K. The experimental valence numbers resulting from an evaluation of the Eu(III)/Eu(II) 3d core levels, are used for calculating band structures using density functional theory. The valence transition significantly changes the band structure as determined by angle-resolved photoemission spectroscopy. In particular, the Eu 5d valence bands are shifted to lower binding energies with increasing Eu 4f occupancy. To a lesser extent, bands derived from the Si 3p and Pd 4d orbitals are also affected. This observation suggests a partial charge transfer between Eu and Pd/Si sites. Comparison with {\it ab-initio} theory shows a good agreement with experiment, in particular concerning the unequal band shift with increasing Eu 4f occupancy.
Conventional cluster and virial expansions are generalized to momentum dependent interparticle potentials. The model with Lorentz contracted hard core potentials is considered, e.g. as hadron gas model. A Van der Waals-type model with a temperature dependent excluded volume is derived. Lorentz contraction effects at given temperature are stronger for light particles and make their effective excluded volume smaller than that of heavy ones.
Sprachwahl und Sprachwahrnehmung sind im Deutschen unabdingbar geprägt durch das Wissen von einer Standardsprache. Dieses Wissen basiert für die meisten Sprecher auf der Erfahrung, dass in der Schule manche sprachliche Formen als korrekt, andere als falsch bewertet werden, außerdem auf der Tatsache, dass es Fixierungen der Regeln des Standards in Lexika und Grammatiken gibt. Wissen und Anerkennung dieses Standards sind unabhängig davon, dass keine dieser Kodifikationen unumstritten ist, dass viele Sprecher die Regeln nicht genau kennen und dass als Vorbilder anerkannte Personen (Nachrichtensprecher, Journalisten bestimmter Zeitschriften, Lehrer, Literaten u.a.) keineswegs einheitliche Regeln verfolgen. Der Standard ist fest assoziiert mit der Erfahrung einer legitimen Regelhaftigkeit, also mit Ordnung. Verwendung von Nonstandard wird mit Bezug auf diese Ordnung und von ihr unterschieden wahrgenommen. Diese relationale Sicht der Dinge ist sowohl subjektiv als auch intersubjektiv.
In der deutschsprachigen Schweiz stehen sich gesprochene Mundarten und geschriebene Standardsprache gegenüber. Außer in formellen Situationen wird Mundart gesprochen, und bis vor kurzem wurde nur selten Mundart geschrieben, sondern die hochdeutsche Schriftsprache. Die Chat-Kommunikation zeigt einerseits durch die nicht-zeitversetzte quasi-direkte Kommunikation wesentliche Züge von Mündlichkeit, die zusammen mit der Informalität im Chat den Mundartgebrauch fördert. Andererseits ist das Medium immer noch die Schrift, welche die Domäne der Standardsprache darstellt. Mundart und Standardsprache stehen sich also in Chaträumen in direkter Konkurrenz gegenüber. Der folgende Beitrag analysiert quantitativ und qualitativ das Neben- und Miteinander der beiden Varietäten in Schweizer Chaträumen und untersucht das Vorkommen und die Bedingungen von Code-Alternation und Code-Switches.
Background Vasoplegic syndrome is frequently observed during cardiac surgery and resembles a complication of high mortality and morbidity. There is a clinical need for therapy and prevention of vasoplegic syndrome during complex cardiac surgical procedures. Therefore, we investigated different strategies in a porcine model of vasoplegia.
Methods We evaluated new medical therapies and prophylaxis to avoid vasoplegic syndrome in a porcine model. After induction of anesthesia, cardiopulmonary bypass was established through median sternotomy and central cannulation. Prolonged aortic cross-clamping (120 min) simulated a complex surgical procedure. The influence of sevoflurane-guided anesthesia (sevoflurane group) and the administration of glibenclamide (glibenclamide group) were compared to a control group, which received standard anesthesia using propofol. Online hemodynamic assessment was performed using PiCCO® measurements. In addition, blood and tissue samples were taken to evaluate hemodynamic effects and the degree of inflammatory response.
Results Glibenclamide was able to break through early vasoplegic syndrome by raising the blood pressure and systemic vascular resistance as well as less need of norepinephrine doses. Sevoflurane reduced the occurrence of the vasoplegic syndrome in the mean of stable blood pressure and less need of norepinephrine doses.
Conclusion Glibenclamide could serve as a potent drug to reduce effects of vasoplegic syndrome. Sevoflurane anesthesia during cardiopulmonary bypass shows less occurrence of vasoplegic syndrome and therefore could be used to prevent it in high-risk patients.
Clinical Perspective; what is new?
* to our knowledge, this is the first randomized in vivo study evaluating the hemodynamic effects of glibenclamide after the onset of vasoplegic syndrome
* furthermore according to literature research, there is no study showing the effect of sevoflurane-guided anesthesia on the occurrence of a vasoplegic syndrome
Clinical Perspective; clinical implications?
to achieve better outcomes after complex cardiac surgery there is a need for optimized drug therapy and prevention of the vasoplegic syndrome
Im Rahmen des Bund-Länder-Programms "Qualitätspakt Lehre" hat die Goethe-Universität Frankfurt erfolgreich das Programm "Starker Start ins Studium" eingeworben. Dadurch verfügt das Institut für Psychologie nun über die personellen Möglichkeiten, die fachliche und soziale Integration neuer Psychologiestudierender im sechssemestrigen Bachelorstudiengang Psychologie zu verbessern. Hierzu wurden zwei obligate je zweisemestrige Lehrmodule entwickelt. In dem vorliegenden Beitrag wird das übergeordnete Lehrkonzept beschrieben und dessen Implementierung im Fach Psychologie als Praxisbeispiel illustriert.
Avventurarsi e poi inoltrarsi nell'opera di Thomas Bernhard non è precisamente come fare una passeggiata, ma la passeggiata è un motivo ricorrente nell'opera bernhardiana (insieme a quella di Handke, di Sebald, di Walser, per fare solo alcuni nomi di passeggiatori nel Novecento di lingua tedesca). Le figure di Bernhard camminano, marciano, corrono, ma in una "direzione opposta" rispetto a quella indicata da Stifter. Talvolta i loro percorsi si snodano nella natura, come quando entrano in un bosco per non fare più ritorno (Gelo, Al limite boschivo, La partita a carte), a volte marciano nel chiuso della loro "casa-prigione", seguendo i percorsi labirintici e infiniti della loro mente (La Fornace, Cemento), altre volte ancora si muovono in un contesto cittadino e metropolitano, a Roma in Estinzione (dove la passeggiata con l'allievo Gambetti conserva un alone aristotelico, il peripatetico) o - più spesso - a Vienna.
Verständnisvolle Dozenten haben weniger Fachwissen : Wirkungen der sprachlichen Anpassung an Laien
(2012)
In der Interaktion mit Studierenden ist schriftliche Online-Kommunikation ein wichtiges Arbeitsmedium für jeden Lehrenden geworden. Die Interaktionspartner haben dabei für ihre Urteilsbildung über den jeweils anderen ausschließlich den geschriebenen Text mit seinen lexikalen und grammatikalischen Merkmalen zur Verfügung. Das Ausmaß der lexikalen Anpassung an die Wortwahl eines Studierenden kann daher einen Einfluss auf die studentische Bewertung ihrer Dozenten hinsichtlich unterschiedlicher Persönlichkeitseigenschaften haben. In der vorliegenden Studie beurteilten Studierende jeweils zwei Dozenten hinsichtlich Verständnis, Gewissenhaftigkeit und Intellekt (IPIP, Goldberg, Johnson, Eber et al., 2006) auf Grundlage einer Emailkommunikation. Der Grad der lexikalen Anpassung der Lehrenden wurde dabei variiert. Es zeigte sich, dass Studierende Dozenten mit umgangssprachlicher Wortwahl als verständnisvoller, gewissenhafter aber tendenziell weniger wissend einschätzen.
Viewpoint effects on object recognition interact with object-scene consistency effects. While recognition of objects seen from “accidental” viewpoints (e.g., a cup from below) is typically impeded compared to processing of objects seen from canonical viewpoints (e.g., the string-side of a guitar), this effect is reduced by meaningful scene context information. In the present study we investigated if these findings established by using photographic images, generalise to 3D models of objects. Using 3D models further allowed us to probe a broad range of viewpoints and empirically establish accidental and canonical viewpoints. In Experiment 1, we presented 3D models of objects from six different viewpoints (0°, 60°, 120°, 180° 240°, 300°) in colour (1a) and grayscaled (1b) in a sequential matching task. Viewpoint had a significant effect on accuracy and response times. Based on the performance in Experiments 1a and 1b, we determined canonical (0°-rotation) and non-canonical (120°-rotation) viewpoints for the stimuli. In Experiment 2, participants again performed a sequential matching task, however now the objects were paired with scene backgrounds which could be either consistent (e.g., a cup in the kitchen) or inconsistent (e.g., a guitar in the bathroom) to the object. Viewpoint interacted significantly with scene consistency in that object recognition was less affected by viewpoint when consistent scene information was provided, compared to inconsistent information. Our results show that viewpoint-dependence and scene context effects generalize to depth rotated 3D objects. This supports the important role object-scene processing plays for object constancy.
Virtuelles Lernen in Gruppen : Rollenspiele und Online-Diskussionen und die Bedeutung von Lerntypen
(2000)
Ziel dieses Beitrags ist, Erfahrungen aus einem virtuellen Tutorium, in dem der Gruppenarbeit und Rollenspielen in Chats eine besondere Bedeutung zukam, auszuwerten. Eingangs wird die Lernumgebung vorgestellt, die auf Basis standardisierter Internetdienste realisiert wurde und vor allem kooperatives Lernen durch Anwendung und Übung in den Mittelpunkt stellte. Diese Evaluation der Veranstaltungen, deren Untersuchung abschließend einen Bezug zwischen Lerntypen und Mediennutzungspräferenzen hergestellt, soll einen Beitrag zur Weiterentwicklung und Ausgestaltung internetbasierter Lehrveranstaltungen leisten.
The brain adapts to the sensory environment. For example, simple sensory exposure can modify the response properties of early sensory neurons. How these changes affect the overall encoding and maintenance of stimulus information across neuronal populations remains unclear. We perform parallel recordings in the primary visual cortex of anesthetized cats and find that brief, repetitive exposure to structured visual stimuli enhances stimulus encoding by decreasing the selectivity and increasing the range of the neuronal responses that persist after stimulus presentation. Low-dimensional projection methods and simple classifiers demonstrate that visual exposure increases the segregation of persistent neuronal population responses into stimulus-specific clusters. These observed refinements preserve the representational details required for stimulus reconstruction and are detectable in post-exposure spontaneous activity. Assuming response facilitation and recurrent network interactions as the core mechanisms underlying stimulus persistence, we show that the exposure-driven segregation of stimulus responses can arise through strictly local plasticity mechanisms, also in the absence of firing rate changes. Our findings provide evidence for the existence of an automatic, unguided optimization process that enhances the encoding power of neuronal populations in early visual cortex, thus potentially benefiting simple readouts at higher stages of visual processing.
The development of super-resolution microscopy (SRM) has widened our understanding of biomolecular structure and function in biological materials. Imaging multiple targets within a single area would elucidate their spatial localization relative to the cell matrix and neighboring biomolecules, revealing multi-protein macromolecular structures and their functional co-dependencies. SRM methods are, however, limited to the number of suitable fluorophores that can be imaged during a single acquisition as well as the loss of antigens during antibody washing and restaining for organic dye multiplexing. We report the visualization of multiple protein targets within the pre- and postsynapse in 350-400 nm thick neuronal tissue sections using DNA-assisted single-molecule localization microscopy. Using antibodies labeled with short DNA oligonucleotides, multiple targets are visualized successively by sequential exchange of fluorophore-labeled complementary oligonucleotides present in the imaging buffer. The structural integrity of the tissue is maintained owing to only a single labelling step during sample preparation. Multiple targets are imaged using a single laser wavelength, minimizing chromatic aberration. This method proved robust for multi-target imaging in semi-thin tissue sections, paving the way towards structural cell biology with single-molecule super-resolution microscopy.
Wie Rolf Parr in seinem Aufsatz 'Liminale und andere Übergänge. Theoretische Modellierung von Grenzzonen, Normalitätsaspekten, Schwellen, Übergängen und Zwischenräumen in Literatur- und Kulturwissenschaft' deutlich macht, ist die Intertextualitäts- und Intermedialitätstheorie, die er im Anschluss an die Arbeiten Michel Foucaults und Jürgen Links vertritt, wesentlich von einem Moment der Grenzüberschreitung bestimmt. An die Stelle klar konturierter Grenzen treten Schwellen als "räumlichtopographische Zonen der Unentschiedenheit", die zugleich als zeitliche Erinnerungsschwellen fungieren. Parr richtet im Rekurs auf Foucault den Blick nicht allein auf diskursive Grenzen der Sagbarkeit durch Ausschlussmechanismen, Verbote etc. Er macht zugleich auf Foucaults frühes Konzept der Heterotopie aufmerksam, wo dieser Grenzziehungen auf bestimmte Raumstrukturen bezieht. Parrs eigenes Interesse liegt in diesem Zusammenhang in der Überführung der diskurstheoretischen Arbeiten Foucaults in eine Interdiskurstheorie, die eben die Schwellen einzelner Diskurse zu überschreiten hätte. Ich möchte hier einen anderen Akzent setzen und die Bedeutung von Schwellenerfahrungen bei Foucault selbst herausarbeiten. Ich konzentriere mich dabei zunächst auf den Begriff des historischen Aprioris aus 'Die Ordnung der Dinge', um daran anschließend auf den Begriff der Heterotopie einzugehen, der die Entstehung der 'Ordnung der Dinge' in den sechziger Jahren in gewisser Weise begleitet und komplementiert. Der Vergleich von Foucaults Schwellendenken mit dem Walter Benjamins soll zugleich erlauben, das Thema des Liminalen im Sinne Parrs als ein Grundmotiv von Foucaults Denken auszumachen.
The W and Z boson production was measured via the muonic decay channel in proton-lead collisions at sNN−−−√=5.02 TeV at the Large Hadron Collider with the ALICE detector. The measurement covers backward (−4.46<ycms<−2.96) and forward (2.03<ycms<3.53) rapidity regions, corresponding to Pb-going and p-going directions, respectively. The Z-boson production cross section, with dimuon invariant mass of 60<mμμ<120 GeV/c2 and muon transverse momentum (pμT) larger than 20 GeV/c, is measured. The production cross section and charge asymmetry of muons from W-boson decays with pμT>10 GeV/c are determined. The results are compared to theoretical calculations both with and without including the nuclear modification of the parton distribution functions. The W-boson production is also studied as a function of the collision centrality: the cross section of muons from W-boson decays is found to scale with the average number of binary nucleon-nucleon collisions within uncertainties.
The W and Z boson production was measured via the muonic decay channel in proton-lead collisions at sNN−−−√=5.02 TeV at the Large Hadron Collider with the ALICE detector. The measurement covers backward (−4.46<ycms<−2.96) and forward (2.03<ycms<3.53) rapidity regions, corresponding to Pb-going and p-going directions, respectively. The Z-boson production cross section, with dimuon invariant mass of 60<mμμ<120 GeV/c2 and muon transverse momentum (pμT) larger than 20 GeV/c, is measured. The production cross section and charge asymmetry of muons from W-boson decays with pμT>10 GeV/c are determined. The results are compared to theoretical calculations both with and without including the nuclear modification of the parton distribution functions. The W-boson production is also studied as a function of the collision centrality: the cross section of muons from W-boson decays is found to scale with the average number of binary nucleon-nucleon collisions within uncertainties.
Die Frage, was Literatur ist, scheint nicht nur die grundlegendste zu sein, die sich der Literaturwissenschaft stellt, sie ist zugleich ihre abgründigste. Grundlegend ist sie, weil sie nach dem Wesen der Literatur fragt und damit eigentlich eine Selbstverständlichkeit aufruft, die die Auseinandersetzung mit Literatur begleitet. Abgründig ist sie, weil auch die scheinbar selbstverständlichsten Definitionen der Literatur bisher nicht zu einer einheitlichen Auffassung vom Wesen der Literatur geführt haben. So steht die Literaturwissenschaft bereits mit der ersten Frage, die sich ihr stellt, vor einem scheinbar unaufhebbaren Dilemma. Auf den Gegenstand angesprochen, der ihr zugehört und der entsprechend über ihre Berechtigung als Wissenschaft Auskunft zu geben vermöchte, bleibt sie im Unklaren.
Weak function word shift
(2004)
The fact that object shift only affects weak pronouns in mainland Scandinavian is seen as an instance of a more general observation that can be made in all Germanic languages: weak function words tend to avoid the edges of larger prosodic domains. This generalisation has been formulated within Optimality Theory in terms of alignment constraints on prosodic structure by Selkirk (1996) in explaining thedistribution of prosodically strong and weak forms of English functionwords, especially modal verbs, prepositions and pronouns. But a purely phonological account fails to integrate the syntactic licensing conditions for object shift in an appropriate way. The standard semantico-syntactic accounts of object shift, onthe other hand, fail to explain why it is only weak pronouns that undergo object shift. This paper develops an Optimality theoretic model of the syntax-phonology interface which is based on the interaction of syntactic and prosodic factors. The account can successfully be applied to further related phenomena in English and German.
Die Bedeutung des philosophischen Programms John McDowells, das schon in der theoretischen Philosophie eine revolutionäre Neuausrichtung vornimmt, kann erst voll erkannt werden, wenn man auch seine Konsequenzen für die praktische Philosophie in den Blick nimmt. Zwar geht Geist und Welt primär von Dilemmata der Erkenntnistheorie aus. Aus McDowells Vorschlag, die Gleichsetzung der äußeren Natur mit dem bedeutungsfreien Raum der Naturgesetze zugunsten einer Konzeption von Gründen in der Welt aufzugeben, ergibt sich aber die Möglichkeit einer so neuartigen Perspektive auf die Natur moralischer Urteile, dass es fast so scheint, als sei McDowells theoretisches Programm auf diesen Gewinn für die praktische Philosophie hin angelegt worden.
Abstract Trial-to-trial variability and spontaneous activity of cortical recordings have been suggested to reflect intrinsic noise. This view is currently challenged by mounting evidence for structure in these phenomena: Trial-to-trial variability decreases following stimulus onset and can be predicted by previous spontaneous activity. This spontaneous activity is similar in magnitude and structure to evoked activity and can predict decisions. Allof the observed neuronal properties described above can be accounted for, at an abstract computational level, by the sampling-hypothesis, according to which response variability reflects stimulus uncertainty. However, a mechanistic explanation at the level of neural circuit dynamics is still missing.
In this study, we demonstrate that all of these phenomena can be accounted for by a noise-free self-organizing recurrent neural network model (SORN). It combines spike-timing dependent plasticity (STDP) and homeostatic mechanisms in a deterministic network of excitatory and inhibitory McCulloch-Pitts neurons. The network self-organizes to spatio-temporally varying input sequences.
We find that the key properties of neural variability mentioned above develop in this model as the network learns to perform sampling-like inference. Importantly, the model shows high trial-to-trial variability although it is fully deterministic. This suggests that the trial-to-trial variability in neural recordings may not reflect intrinsic noise. Rather, it may reflect a deterministic approximation of sampling-like learning and inference. The simplicity of the model suggests that these correlates of the sampling theory are canonical properties of recurrent networks that learn with a combination of STDP and homeostatic plasticity mechanisms.
Author Summary Neural recordings seem very noisy. If the exact same stimulus is shown to an animal multiple times, the neural response will vary. In fact, the activity of a single neuron shows many features of a stochastic process. Furthermore, in the absence of a sensory stimulus, cortical spontaneous activity has a magnitude comparable to the activity observed during stimulus presentation. These findings have led to a widespread belief that neural activity is indeed very noisy. However, recent evidence indicates that individual neurons can operate very reliably and that the spontaneous activity in the brain is highly structured, suggesting that much of the noise may in fact be signal. One hypothesis regarding this putative signal is that it reflects a form of probabilistic inference through sampling. Here we show that the key features of neural variability can be accounted for in a completely deterministic network model through self-organization. As the network learns a model of its sensory inputs, the deterministic dynamics give rise to sampling-like inference. Our findings show that the notorious variability in neural recordings does not need to be seen as evidence for a noisy brain. Instead it may reflect sampling-like inference emerging from a self-organized learning process.
White matter abnormalities across different epilepsy syndromes in adults: an ENIGMA Epilepsy study
(2019)
The epilepsies are commonly accompanied by widespread abnormalities in cerebral white matter. ENIGMA-Epilepsy is a large quantitative brain imaging consortium, aggregating data to investigate patterns of neuroimaging abnormalities in common epilepsy syndromes, including temporal lobe epilepsy, extratemporal epilepsy, and genetic generalized epilepsy. Our goal was to rank the most robust white matter microstructural differences across and within syndromes in a multicentre sample of adult epilepsy patients. Diffusion-weighted MRI data were analyzed from 1,069 non-epileptic controls and 1,249 patients: temporal lobe epilepsy with hippocampal sclerosis (N=599), temporal lobe epilepsy with normal MRI (N=275), genetic generalized epilepsy (N=182) and nonlesional extratemporal epilepsy (N=193). A harmonized protocol using tract-based spatial statistics was used to derive skeletonized maps of fractional anisotropy and mean diffusivity for each participant, and fiber tracts were segmented using a diffusion MRI atlas. Data were harmonized to correct for scanner-specific variations in diffusion measures using a batch-effect correction tool (ComBat). Analyses of covariance, adjusting for age and sex, examined differences between each epilepsy syndrome and controls for each white matter tract (Bonferroni corrected at p<0.001). Across “all epilepsies” lower fractional anisotropy was observed in most fiber tracts with small to medium effect sizes, especially in the corpus callosum, cingulum and external capsule. Less robust effects were seen with mean diffusivity. Syndrome-specific fractional anisotropy and mean diffusivity differences were most pronounced in patients with hippocampal sclerosis in the ipsilateral parahippocampal cingulum and external capsule, with smaller effects across most other tracts. Those with temporal lobe epilepsy and normal MRI showed a similar pattern of greater ipsilateral than contralateral abnormalities, but less marked than those in patients with hippocampal sclerosis. Patients with generalized and extratemporal epilepsies had pronounced differences in fractional anisotropy in the corpus callosum, corona radiata and external capsule, and in mean diffusivity of the anterior corona radiata. Earlier age of seizure onset and longer disease duration were associated with a greater extent of microstructural abnormalities in patients with hippocampal sclerosis. We demonstrate microstructural abnormalities across major association, commissural, and projection fibers in a large multicentre study of epilepsy. Overall, epilepsy patients showed white matter abnormalities in the corpus callosum, cingulum and external capsule, with differing severity across epilepsy syndromes. These data further define the spectrum of white matter abnormalities in common epilepsy syndromes, yielding new insights into pathological substrates that may be used to guide future therapeutic and genetic studies.
In recent years, research in parsing has extended in several new directions. One of these directions is concerned with parsing languages other than English. Treebanks have become available for many European languages, but also for Arabic, Chinese, or Japanese. However, it was shown that parsing results on these treebanks depend on the types of treebank annotations used. Another direction in parsing research is the development of dependency parsers. Dependency parsing profits from the non-hierarchical nature of dependency relations, thus lexical information can be included in the parsing process in a much more natural way. Especially machine learning based approaches are very successful (cf. e.g.). The results achieved by these dependency parsers are very competitive although comparisons are difficult because of the differences in annotation. For English, the Penn Treebank has been converted to dependencies. For this version, Nivre et al. report an accuracy rate of 86.3%, as compared to an F-score of 92.1 for Charniaks parser. The Penn Chinese Treebank is also available in a constituent and a dependency representations. The best results reported for parsing experiments with this treebank give an F-score of 81.8 for the constituent version and 79.8% accuracy for the dependency version. The general trend in comparisons between constituent and dependency parsers is that the dependency parser performs slightly worse than the constituent parser. The only exception occurs for German, where F-scores for constituent plus grammatical function parses range between 51.4 and 75.3, depending on the treebank, NEGRA or TüBa-D/Z. The dependency parser based on a converted version of Tüba-D/Z, in contrast, reached an accuracy of 83.4%, i.e. 12 percent points better than the best constituent analysis including grammatical functions.
canning tunneling microscopy (STM) is perhaps the most promising way to detect the superconducting gap size and structure in the canonical unconventional superconductor Sr2RuO4 directly. However, in many cases, researchers have reported being unable to detect the gap at all in simple STM conductance measurements. Recently, an investigation of this issue on various local topographic structures on a Sr-terminated surface found that superconducting spectra appeared only in the region of small nanoscale canyons, corresponding to the removal of one RuO surface layer. Here, we analyze the electronic structure of various possible surface structures using first principles methods, and argue that bulk conditions favorable for superconductivity can be achieved when removal of the RuO layer suppresses the RuO4 octahedral rotation locally. We further propose alternative terminations to the most frequently reported Sr termination where superconductivity surfaces should be observed.
Several studies suggested that transcription factor (TF) binding to DNA may be impaired or enhanced by DNA methylation. We present MeDeMo, a toolbox for TF motif analysis that combines information about DNA methylation with models capturing intra-motif dependencies. In a large-scale study using ChIP-seq data for 335 TFs, we identify novel TFs that are affected by DNA methylation. Overall, we find that CpG methylation decreases the likelihood of binding for the majority of TFs. For a considerable subset of TFs, we show that intra-motif dependencies are pivotal for accurately modelling the impact of DNA methylation on TF binding.
Wikis in der Hochschullehre
(2012)
Dieser Beitrag gibt einen Überblick über Einsatzszenarien von Wikis in Lern- und Lehrprozessen und deren Eignung für die kollaborative Wissensproduktion, während zugleich Einschränkungen, Bedingungen und Gestaltungsempfehlungen thematisiert werden. Zudem werden Erfahrungen mit verschiedenen Wiki-Anwendungen an der Universität Frankfurt dokumentiert, die vom begleitenden Einsatz im Seminar bis hin zur studentisch initiierten Bereitstellung studienbegleitender Materialien reichen. Die vorher ausgearbeiteten Aspekte werden nochmals anhand der Beispiele aufgegriffen und ihrer Praxisrelevanz verdeutlicht.
Chern numbers can be calculated within a frame of vortex fields related to phase conventions of a wave function. In a band protected by gaps the Chern number is equivalent to the total number of flux carrying vortices. In the presence of topological defects like Dirac cones this method becomes problematic, in particular if they lack a well-defined winding number. We develop a scheme to include topological defects into the vortex field frame. A winding number is determined by the behavior of the phase in reciprocal space when encircling the defect's contact point. To address the possible lack of a winding number we utilize a more general concept of winding vectors. We demonstrate the usefulness of this ansatz on Dirac cones generated from bands of the Hofstadter model.
Chern numbers can be calculated within a frame of vortex fields related to phase conventions of a wave function. In a band protected by gaps the Chern number is equivalent to the total number of flux carrying vortices. In the presence of topological defects like Dirac cones this method becomes problematic, in particular if they lack a well-defined winding number. We develop a scheme to include topological defects into the vortex field frame. A winding number is determined by the behavior of the phase in reciprocal space when encircling the defect's contact point. To address the possible lack of a winding number we utilize a more general concept of winding vectors. We demonstrate the usefulness of this ansatz on Dirac cones generated from bands of the Hofstadter model.
Der Workshop "Nationale Spezifika und internationale Aspekte in der Wissenschaftsentwicklung – unter besonderer Berücksichtigung der Narratologie" soll, so die Organisatoren in ihrer Einladung – "Gelegenheit bieten, Bedingungen und Möglichkeiten integrativer Ansätze zur Untersuchung von Wissenschaftsprozessen zu diskutieren und wichtige Faktoren der Wissenschaftsentwicklung zu benennen und kritisch zu beleuchten." Die Produktion, Distribution und Rezeption von Wissenssystemen vollziehe sich, schreiben die Organisatoren, "in unterschiedlichen nationalen und internationalen sozialen Räumen, die sowohl die Form als auch den kognitiven Gehalt von Theorien mitunter stark mitstrukturieren, ihre Durchsetzung begünstigen oder behindern. Das wird besonders deutlich, wenn man Transferprozesse von Theorien verfolgt." Den Begriff des Wissenstransfers, der hier in Anschlag gebracht wird, möchte ich in meinem Beitrag einer terminologischen Klärung zuführen. Dazu möchte ich zunächst einige terminologische Überlegungen über den Status der Teilbegriffe anstellen, aus denen der Begriff zusammengesetzt ist (I.), dann die Verwendung des Begriffs in verschiedenen disziplinären Kontexten beobachten (II.) und schließlich einen Vorschlag für eine differenzierte Verwendung des Begriffs als Analysekategorie der Wissenschaftsentwicklung machen (III).
Die Driften der Wörter in öffentlichen Räumen sind vielfältig. Neue Wortentwicklungen belegen unterschiedliche Interessen, "chillen" und "dissen" andere als das in der konservativen Züricher Zeitung zuerst erschienene "share-holder-value". Im Folgenden soll eine sinnbezoge Verallgemeinerung unternommen werden, die die Handlungen der Akteure mit der strukturellen Ebene verbindet. Die Veränderungen in den Verwendungen sollen zu strukturellen sozialen und sprachlichen Rahmenbedingungen in Bezug gesetzt werden. Wie werden Neuerungen und Änderungen der Anwendungsbedingungen von Wörtern vor dem Hintergrund des Wissens um die traditionelle Standardsprache und deren soziale Funktion wahrgenommen? Welche Funktionen haben Neologismen in Abgrenzung zu diesem Standard?
W±-boson production in p–Pb collisions at √sNN = 8.16 TeV and Pb–Pb collisions at √sNN = 5.02 TeV
(2022)
The production of the W± bosons measured in p−Pb collisions at a centre-of-mass energy per nucleon−nucleon collision sNN−−−−√=8.16 TeV and Pb−Pb collisions at sNN−−−−√=5.02 TeV with ALICE at the LHC is presented. The W± bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region −4<ημlab<−2.5 with transverse momentum pμT>10 GeV/c. While in Pb−Pb collisions the measurements are performed in the forward (2.5<yμcms<4) rapidity region, in p−Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward (−4.46<yμcms<−2.96) and forward (2.03<yμcms<3.53) rapidity regions. The W− and W+ production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p−Pb collision centrality, the production cross sections of the W− and W+ bosons are combined and normalised to the average number of binary nucleon−nucleon collision ⟨Ncoll⟩. In Pb−Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W±-boson cross sections in p−Pb and Pb−Pb collisions is also reported. The results are compared with perturbative QCD (pQCD) calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDF (nPDFs) and in particular of the light-quark distributions.
W±-boson production in p–Pb collisions at √sNN = 8.16 TeV and Pb–Pb collisions at √sNN = 5.02 TeV
(2022)
The production of the W± bosons measured in p−Pb collisions at a centre-of-mass energy per nucleon−nucleon collision sNN−−−−√=8.16 TeV and Pb−Pb collisions at sNN−−−−√=5.02 TeV with ALICE at the LHC is presented. The W± bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region −4<ημlab<−2.5 with transverse momentum pμT>10 GeV/c. While in Pb−Pb collisions the measurements are performed in the forward (2.5<yμcms<4) rapidity region, in p−Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward (−4.46<yμcms<−2.96) and forward (2.03<yμcms<3.53) rapidity regions. The W− and W+ production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p−Pb collision centrality, the production cross sections of the W− and W+ bosons are combined and normalised to the average number of binary nucleon−nucleon collision ⟨Ncoll⟩. In Pb−Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W±-boson cross sections in p−Pb and Pb−Pb collisions is also reported. The results are compared with perturbative QCD (pQCD) calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDF (nPDFs) and in particular of the light-quark distributions.
W±-boson production in p–Pb collisions at √sNN = 8.16 TeV and Pb–Pb collisions at √sNN = 5.02 TeV
(2023)
The production of the W± bosons measured in p−Pb collisions at a centre-of-mass energy per nucleon−nucleon collision sNN−−−−√=8.16 TeV and Pb−Pb collisions at √sNN=5.02 TeV with ALICE at the LHC is presented. The W± bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region −4<ημlab<−2.5 with transverse momentum pμT>10 GeV/c. While in Pb−Pb collisions the measurements are performed in the forward (2.5<yμcms<4) rapidity region, in p−Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward (−4.46<yμcms<−2.96) and forward (2.03<yμcms<3.53) rapidity regions. The W− and W+ production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p−Pb collision centrality, the production cross sections of the W− and W+ bosons are combined and normalised to the average number of binary nucleon−nucleon collision ⟨Ncoll⟩. In Pb−Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W±-boson cross sections in p−Pb and Pb−Pb collisions is also reported. The results are compared with perturbative QCD (pQCD) calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDF (nPDFs) and in particular of the light-quark distributions.
We report measurements of Xi and Xi-bar hyperon absolute yields as a function of rapidity in 158 GeV/c Pb+Pb collisions. At midrapidity, dN/dy = 2.29 +/- 0.12 for Xi, and 0.52 +/- 0.05 for Xi-bar, leading to the ratio of Xi-bar/Xi = 0.23 +/- 0.03. Inverse slope parameters fitted to the measured transverse mass spectra are of the order of 300 MeV near mid-rapidity. The estimated total yield of Xi particles in Pb+Pb central interactions amounts to 7.4 +/- 1.0 per collision. Comparison to Xi production in properly scaled p+p reactions at the same energy reveals a dramatic enhancement (about one order of magnitude) of Xi production in Pb+Pb central collisions over elementary hadron interactions.
Results of the production of Xi and Xi-bar hyperons in central Pb+Pb interactions at 158 GeV/c per nucleon are presented. This analysis utilises a global reconstruction procedure, which allows a measurement of 4pi integrated yields to be made for the first time. Inverse slope paramters, which are determined from an exponential fit to the transverse mass spectra, are shown. Central rapidity densities are found to be 1.49 +- 0.08 and 0.33 +- 0.04 per event per unit of rapidity for Xi and Xi-bar respectively. Yields integrated to full phase space are 4.12 +- 0.02 and 0.77 +- 0.04 for Xi and Xi-bar. The ratio of Xi-bar/Xi at mid-rapidity is 0.22 +- 0.03.
In this paper, we introduce an extension of the XMG system (eXtensibleMeta-Grammar) in order to allow for the description of Multi-Component Tree Adjoining Grammars. In particular, we introduce the XMG formalism and its implementation, and show how the latter makes it possible to extend the system relatively easily to different target formalisms, thus opening the way towards multi-formalism.
Z-boson production in p–Pb collisions at √sNN = 8.16 TeV and Pb–Pb collisions at √sNN = 5.02 TeV
(2021)
Measurement of Z-boson production in p-Pb collisions at sNN−−−√=8.16 TeV and Pb-Pb collisions at sNN−−−√=5.02 TeV is reported. It is performed in the dimuon decay channel, through the detection of muons with pseudorapidity −4<ημ<−2.5 and transverse momentum pμT>20 GeV/c in the laboratory frame. The invariant yield and nuclear modification factor are measured for opposite-sign dimuons with invariant mass 60<mμμ<120 GeVc2 and rapidity 2.5<yμμcms<4. They are presented as a function of rapidity and, for the Pb-Pb collisions, of centrality as well. The results are compared with theoretical calculations, both with and without nuclear modifications to the Parton Distribution Functions (PDFs). In p-Pb collisions the center-of-mass frame is boosted with respect to the laboratory frame, and the measurements cover the backward (−4.46<yμμcms<−2.96) and forward (2.03<yμμcms<3.53) rapidity regions. For the p-Pb collisions, the results are consistent within experimental and theoretical uncertainties with calculations that include both free-nucleon and nuclear-modified PDFs. For the Pb-Pb collisions, a 3.4σ deviation is seen in the integrated yield between the data and calculations based on the free-nucleon PDFs, while good agreement is found once nuclear modifications are considered.
Z-boson production in p–Pb collisions at √sNN = 8.16 TeV and Pb–Pb collisions at √sNN = 5.02 TeV
(2020)
Measurement of Z-boson production in p-Pb collisions at sNN−−−√=8.16 TeV and Pb-Pb collisions at sNN−−−√=5.02 TeV is reported. It is performed in the dimuon decay channel, through the detection of muons with pseudorapidity −4<ημ<−2.5 and transverse momentum pμT>20 GeV/c in the laboratory frame. The invariant yield and nuclear modification factor are measured for opposite-sign dimuons with invariant mass 60<mμμ<120 GeVc2 and rapidity 2.5<yμμcms<4. They are presented as a function of rapidity and, for the Pb-Pb collisions, of centrality as well. The results are compared with theoretical calculations, both with and without nuclear modifications to the Parton Distribution Functions (PDFs). In p-Pb collisions the center-of-mass frame is boosted with respect to the laboratory frame, and the measurements cover the backward (−4.46<yμμcms<−2.96) and forward (2.03<yμμcms<3.53) rapidity regions. For the p-Pb collisions, the results are consistent within experimental and theoretical uncertainties with calculations that include both free-nucleon and nuclear-modified PDFs. For the Pb-Pb collisions, a 3.4σ deviation is seen in the integrated yield between the data and calculations based on the free-nucleon PDFs, while good agreement is found once nuclear modifications are considered.
Zinsänderungsrisiken und langfristige Zinsbindung vor dem Hintergrund der hessischen Zinsswaps
(2019)
Johannes Kasinger, Lukas Nöh und Alfons Weichenrieder nehmen die derzeitige Niedrigzinsphase und die Debatte um den Einsatz von Zinsswaps in Hessen zum Anlass, um die Fristigkeitsstruktur der Staatsschulden sowie den Einsatz von langfristigen Zinsswaps zu erörtern. Die Autoren betonen, dass im Gegensatz zu einem privaten Bauherrn der Staat nicht für sich wirtschaftet, sondern als Sachwalter der Steuerzahler agieren sollte. Den Zinserhöhungsrisiken des Staates stehen Zinserhöhungschancen der Steuerzahler in deren Funktion als Kreditgeber gegenüber. Letzteres schwächt das Argument für langfristige Verschuldung, sei es durch die Emission langfristiger Anleihen oder durch den Einsatz von Finanzderivaten. Grundsätzlich kann eine Glättung der Zinslast allerdings dabei helfen, die für den Schuldendienst notwendigen Steuern zu glätten und die Zusatzlast der Besteuerung zu mindern.