Refine
Year of publication
Document Type
- Article (31215)
- Part of Periodical (11563)
- Book (8309)
- Doctoral Thesis (5728)
- Part of a Book (3967)
- Working Paper (3387)
- Review (2939)
- Contribution to a Periodical (2368)
- Preprint (2182)
- Report (1560)
Language
- German (42832)
- English (29414)
- French (1060)
- Portuguese (840)
- Spanish (309)
- Croatian (302)
- Multiple languages (263)
- Italian (198)
- mis (174)
- Turkish (168)
Has Fulltext
- yes (75884) (remove)
Keywords
- Deutsch (1076)
- Literatur (868)
- taxonomy (766)
- Deutschland (553)
- Rezension (511)
- new species (452)
- Rezeption (354)
- Frankfurt <Main> / Universität (341)
- Übersetzung (329)
- Geschichte (300)
Institute
- Medizin (7723)
- Präsidium (5203)
- Physik (4512)
- Extern (2738)
- Wirtschaftswissenschaften (2696)
- Gesellschaftswissenschaften (2373)
- Biowissenschaften (2187)
- Biochemie und Chemie (1978)
- Frankfurt Institute for Advanced Studies (FIAS) (1771)
- Center for Financial Studies (CFS) (1630)
Search for X(3872)→π⁰π⁰χc₁,₂
(2024)
Using 10.1 fb−1 of e+e− collision data collected by the BESIII detector with center-of-mass energies between 4.15 GeV and 4.30 GeV, we search for the decays X(3872)→π0π0χc1,2, where the X(3872) is produced in e+e−→γX(3872). No evidence above 3σ is found for either decay. Upper limits at the 90% C.L. on the branching fractions of X(3872)→π0π0χc1,2 normalized to the branching fraction of X(3872)→π+π−J/ψ are set to be B(X(3872)→π0π0χc1)/B(X(3872)→π+π−J/ψ)<1.1 and B(X(3872)→π0π0χc2)/B(X(3872)→π+π−J/ψ)<0.5, taking into account both statistical and systematic uncertainties.
We perform the first investigation of the process e+e−→K+K−ψ(2S) and report its Born cross sections over a range of center-of-mass energies from 4.699 to 4.951~GeV. The measurements are carried out using several partial reconstruction techniques using data samples collected by the BESIII detector with a total integrated luminosity of 2.5~fb−1. We search for new tetraquark candidates Z±cs in the decays Z±cs→K±ψ(2S). No significant Z±cs signals are observed.
Using (2.712±0.014)×109 ψ(3686) events collected with the BESIII detector operating at the BEPCII, we find an evidence of the ηc(2S)→K+K−η′ decay with a statistical significance of 3.1σ. Its decay branching fraction is measured to be (12.24±4.60(stat.)±2.37(syst.)±4.68(extr.))×10−4, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is from the branching fraction of the ψ(3686)→γηc(2S) decay. The upper limit on the product branching fraction B[ψ(3686)→γηc(2S)]× B[ηc(2S)→K+K−η′] is set to be 1.14×10−6 at 90% confidence level. In addition, the branching fractions of χc1→K+K−η′ and χc2→K+K−η′ are updated to be (8.47±0.09(stat.)±0.47(syst.))×10−4 and (1.53±0.04(stat.)±0.08(syst.))×10−4, respectively. The precision is improved by twofold.
Der Artikel gibt einen Überblick über die unterschiedlichen Sammlungsbestände von Comics, Graphic Novels und Manga in wissenschaftlichen Bibliotheken in Deutschland. Im weiteren Verlauf wird ein Schwerpunkt auf die Herausforderungen und Probleme in Bezug auf Bestandsaufbau, Erschließung, Archivierung bzw. Verfügbarmachung sowie Findmittel gelegt.
Observation of χcJ → 3(K⁺K⁻)
(2024)
By analyzing (27.12±0.14)×108 𝜓(3686) events collected with the BESIII detector operating at the BEPCII collider, the decay processes 𝜒𝑐𝐽→3(𝐾+𝐾−) (𝐽=0, 1, 2) are observed for the first time with statistical significances of 8.2𝜎, 8.1𝜎, and 12.4𝜎, respectively. The product branching fractions of 𝜓(3686)→𝛾𝜒𝑐𝐽, 𝜒𝑐𝐽→3(𝐾+𝐾−) are presented and the branching fractions of 𝜒𝑐𝐽→3(𝐾+𝐾−) decays are determined to be ℬ𝜒𝑐0→3(𝐾+𝐾−)=(10.7±1.8±1.1)×10−6, ℬ𝜒𝑐1→3(𝐾+𝐾−)=(4.2±0.9±0.5)×10−6, and ℬ𝜒𝑐2→3(𝐾+𝐾−)=(7.2±1.1±0.8)×10−6, where the first uncertainties are statistical and the second are systematic.
Observation of χcJ → 3(K⁺K⁻)
(2023)
By analyzing (27.12±0.14)×108 ψ(3686) events collected with the BESIII detector operating at the BEPCII collider, the decay processes χcJ→3(K+K−) (J=0,1,2) are observed for the first time with statistical significances of 8.2σ, 8.1σ, and 12.4σ, respectively. The product branching fractions of ψ(3686)→γχcJ, χcJ→3(K+K−) are presented and the branching fractions of χcJ→3(K+K−) decays are determined to be Bχc0→3(K+K−)=(10.7±1.8±1.1)×10−6, Bχc1→3(K+K−)=(4.2±0.9±0.5)×10−6, and Bχc2→3(K+K−)=(7.2±1.1±0.8)×10−6, where the first uncertainties are statistical and the second are systematic.
Using data samples with an integrated luminosity of 6.4~fb−1 collected by the BESIII detector operating at the BEPCII storage ring, the process of e+e−→γϕJ/ψ is studied. The processes of e+e−→ϕχc1,c2, χc1,c2→γJ/ψ are observed with a significance of more than 10σ. The s√-dependent cross section of e+e−→ϕχc1,c2 is measured between 4.600 and 4.951~GeV, and evidence of a resonance structure is found for the first time in the ϕχc2 process. We also search for the processes of e+e−→γX(4140), γX(4274) and γX(4500) via the γϕJ/ψ final state, but no obvious structures are found. The upper limits on the production cross section times the branching fraction for these processes at the 90% confidence level are reported.
The cross section of the process e+e−→K+K− is measured at a number of center-of-mass energies s√ from 2.00 to 3.08 GeV with the BESIII detector at the Beijing Electron Positron Collider (BEPCII). The results provide the best precision achieved so far. A resonant structure around 2.2 GeV is observed in the cross section line shape. A Breit-Wigner fit yields a mass of M=2239.2±7.1±11.3~and a width of Γ=139.8±12.3±20.6 MeV, where the first uncertainties are statistical and the second ones are systematic. In addition, the time-like electromagnetic form factor of the kaon is determined at the individual center-of-mass energy points.
Using a 3.19 fb−1 data sample collected at an 𝑒+𝑒− center-of-mass energy of 𝐸cm=4.178 GeV with the BESIII detector, we measure the branching fraction of the leptonic decay 𝐷+𝑠→𝜇+𝜈𝜇 to be ℬ𝐷+𝑠→𝜇+𝜈𝜇=(5.49±0.16stat±0.15syst)×10−3. Combining our branching fraction with the masses of the 𝐷+𝑠 and 𝜇+ and the lifetime of the 𝐷+𝑠, we determine 𝑓𝐷+𝑠|𝑉𝑐𝑠|=246.2±3.6stat±3.5syst MeV. Using the 𝑐→𝑠 quark mixing matrix element |𝑉𝑐𝑠| determined from a global standard model fit, we evaluate the 𝐷+𝑠 decay constant 𝑓𝐷+𝑠=252.9±3.7stat±3.6syst MeV. Alternatively, using the value of 𝑓𝐷+𝑠 calculated by lattice quantum chromodynamics, we find |𝑉𝑐𝑠|=0.985±0.014stat±0.014syst. These values of ℬ𝐷+𝑠→𝜇+𝜈𝜇, 𝑓𝐷+𝑠|𝑉𝑐𝑠|, 𝑓𝐷+𝑠 and |𝑉𝑐𝑠| are each the most precise results to date.
Using a data sample of 448.1×106 𝜓(3686) events collected at √𝑠=3.686 GeV with the BESIII detector at the Beijing Electron-Positron Collider II, we search for the rare decay 𝐽/𝜓→𝜙𝑒+𝑒− via 𝜓(3686)→𝜋+𝜋−𝐽/𝜓. No signal events are observed and the upper limit on the branching fraction is set to be ℬ(𝐽/𝜓→𝜙𝑒+𝑒−)<1.2×10−7 at the 90% confidence level, which is still about one order of magnitude higher than the Standard Model prediction.
Using a data sample of 448.1×106 ψ(3686) events collected at s√= 3.686 GeV with the BESIII detector at the BEPCII, we search for the rare decay J/ψ→ϕe+e− via ψ(3686)→π+π−J/ψ. No signal events are observed and the upper limit on the branching fraction is set to be B(J/ψ→ϕe+e−)<1.2×10−7 at the 90\% confidence level, which is still about one order of magnitude higher than the Standard Model prediction.
Dielectrons are an excellent probe for the QCD matter created in created in ultra-relativistic heavy-ion collisions, since they are emitted during the whole evolution of the collision and do not interact strongly with the medium. To isolate the QGP signals, measurement of the dielectron production in vacuum and its modifications due to the presence of cold nuclear matter is necessary. We present and discuss results from a low magnetic field detector setup in proton-proton collisions at √s = 13 TeV, as well as the measurement of dielectron production in pp, p-Pb, and Pb-Pb collisions at √sNN = 5 TeV.
The attention on the protein PURA has increased recently following the discovery of the rare PURA Syndrome. This neurodevelopmental disorder is caused by de novo mutations in the PURA gene. Notably, our collaborators could show that the protein PURA can bind DNA and RNA in vitro. As a result, I was motivated to explore PURA's cellular RNAbinding activity. Furthermore, I inquired on the connection of PURA-RNA binding to the cellular effect of a reduction of functional PURA as present in PURA Syndrome patients.
To investigate the binding of PURA and the impact of PURA de ciency on cellular RNA and protein expression, I performed an integrative computational analysis of multimodal data from complementary high-throughput experiments. An essential component was the examination of UV Crosslinking and immunoprecipitation (CLIP) experiments, which can query the global RNA-binding behaviour of a given protein in a cellular context. As the processing and analysis of CLIP data are rather complex, I introduce an automated command line tool for the processing of CLIP data named racoon_clip as part of this dissertation. Therefore, this dissertation comprises two major segments. Firstly, I describe the implementation and usage of racoon clip for CLIP data analysis. Secondly, I discuss my research on the protein PURA, demonstrating its global RNA-binding properties, the effects of PURA depletion and its association with neuronal functions and P-bodies, among others.
racoon_clip is a command line application that I have developed for processing of individualnucleotide resolution CLIP (iCLIP) and enhanced CLIP (eCLIP) experiments - two of the most commonly used types of CLIP experiments - in a comparable and user-friendly way.
For this, I built racoon_clip as an automated work how that encompasses all CLIP processing steps from raw data to single-nucleotide resolution crosslink events. racoon_clip is available as a command line tool that users can run with a single command. The work how is implemented with Snakemake work how management providing computational advantage tages including parallelisation, scalability and portability of the work how. The main task of racoon_clip is to extract single-nucleotide crosslink events from iCLIP, iCLIP2, eCLIP and similar data types. To strike a balance between being highly customisable and easy to use, racoon_clip supplies pre-set options for the most common types of experiments.
Additionally, it is possible for users to create a custom setup of barcode and adapter architectures, which allows them to use the software for other types of CLIP data. While accounting for the different architectures in the reads, the performed central processing steps remain the same. This leads to a high degree of comparability between the different experiment types, which I demonstrate in the exemplary processing of U2AF2 iCLIP and eCLIP data. Taken together, I am confident that racoon_clip will be beneficial to numerous researchers interested in RNA-Protein interactions as it offers easily accessible processing for CLIP data and enhances the comparability of multiple CLIP datasets across di erent experiment types.
In the second part of this dissertation, I focus on the cellular function of the RNAbinding protein PURA. Through in-depth computational analysis of one iCLIP data set of endogenous PURA and two iCLIP data sets of overexpressed PURA in HeLa cells, I establish that PURA is a global RNA-binding protein. It preferentially binds RNAs in either the coding sequence (CDS) or the 3' untranslated region (3'UTR) of mature protein-coding transcripts by recognising a Purine-rich degenerated sequence motif. Even though overexpression of PURA results in less specific binding behaviour, the same overall binding patterns as from endogenous PURA persist. Overall characteristics of PURA binding remain similar in three distinct PURA iCLIP data sets with and without PURA overexpression.
To learn about the molecular consequences of a depletion of functional PURA in a cellular context, I used a 50% reduction of PURA in HeLa cells as a model for the heterozygous loss of PURA in PURA Syndrome and evaluated its impact on global RNA and protein expression. The results demonstrate that PURA depletion globally a ects RNA and protein expression. Additionally, I integrate PURA RNA binding with the changes in expression of RNAs and proteins in the context of PURA depletion. This reveals 234 targets of PURA that are bound by PURA and are impacted at both RNA and protein levels by the PURA protein. RNAs that are bound by PURA or change in abundance upon PURA depletion are enriched in neuronal development factors, RNA lifecycle regulators, and mitochondrial factors, among others. Consistent with a possible role of PURA in neuronal transport, there is considerable overlap between PURA bound transcripts and transcripts, that are transported to the dendritic end of neurons.
Notably, there is a link between PURA and P-bodies, as documented by the enrichment of PURA-bound RNAs in both the P-body and stress granule transcriptome. Further, PURA was found by our collaborators to be localised within P-bodies and P-body numbers were strongly reduced in cells that are depleted of PURA. This absence might be attributed to the downregulation of the proteins encoded by the PURA targets LSM14A and DDX6 as both of them were previously identified as essential for P-body formation.
Overall, the reduction of P-body numbers in PURA depletion, the neuronal function of PURA, and its association with mitochondria and RNA lifecycle regulation may indicate the cellular foundation of both PURA Syndrome and related neuronal diseases.
In summary, I present a versatile and user-friendly computational tool for the analysis of CLIP data. Subsequently, I conduct a thorough computational analysis of CLIP and other high-throughput data in the context of the RNA-binding protein PURA, which offers valuable insights into the cellular functions of PURA. These insights advance our understanding of the impact of PURA loss in PURA Syndrome and other disease contexts.
Stimulated emission depletion (STED) microscopy is a super-resolution technique that surpasses the diffraction limit and has contributed to the study of dynamic processes in living cells. However, high laser intensities induce fluorophore photobleaching and sample phototoxicity, limiting the number of fluorescence images obtainable from a living cell. Here, we address these challenges by using ultra-low irradiation intensities and a neural network for image restoration, enabling extensive imaging of single living cells. The endoplasmic reticulum (ER) was chosen as the target structure due to its dynamic nature over short and long timescales. The reduced irradiation intensity combined with denoising permitted continuous ER dynamics observation in living cells for up to 7 hours with a temporal resolution of seconds. This allowed for quantitative analysis of ER structural features over short (seconds) and long (hours) timescales within the same cell, and enabled fast 3D live-cell STED microscopy. Overall, the combination of ultra-low irradiation with image restoration enables comprehensive analysis of organelle dynamics over extended periods in living cells.
Five new species of the spider genus Heteropoda Latreille, 1804 (Araneae: Sparassidae) from China
(2024)
Five new species of Heteropoda (Araneae, Sparassidae, Heteropodinae) are described from China: H. bawanglingensis sp. nov. (female; Hainan), H. dulongensis sp. nov. (male, female; Yunnan), H. hainanensis sp. nov. (male, female; Hainan), H. longa sp. nov. (female; Guizhou), and H. vaginalis sp. nov. (female; Yunnan). We provide descriptions and illustrations for each species as well as a distribution map in the current paper.
Scalibregmatidae Malmgren, 1867 is a family of annelids, with only few taxa reported from Brazil. In this work, we describe two new species of Asclerocheilus Ashworth, 1901. The new species A. geiseae sp. nov. and A. blakei sp. nov. were collected during scientific expeditions to the Espírito Santo and Campos sedementary basins. These expeditions were coordinated by PETROBRAS/CENPES. The species A. geiseae sp. nov. is unique among its congeners by the presence of acicular spines with rounded and curved tips in two rows. The second species, A. blakei sp. nov., differs from its congeners by the combination of the presence of a trapezoidal prostomium, acicular spines on chaetigers 1–3, lyrate chaetae from chaetiger 3 on notopodia and 2 on neuropodia. Moreover, we report the species A. tropicus Blake, 1981 from the localities sampled on this study. We also provide an identification key to all species of Asclerocheilus of the world.
Sipunculans are a poorly studied group in the Tropical Eastern Pacific. For the Southern Mexican Pacific (SMP) there is only one record of a sipunculan species. The main objective of this work was to determine the species composition of the phylum Sipuncula present in the SMP. The study area covered three Mexican states: Guerrero, Oaxaca and Chiapas; specimens from 28 localities were examined from both intertidal and subtidal zones. A total of 551 specimens were reviewed, from which 11 species were identified. Five of them have previously been recorded in the Tropical Eastern Pacific (TEP): Apionsoma (A.) hespera comb. nov., A. (Edmondsius) pectinatum, Aspidosiphon (A.) elegans, Phascolosoma (P.) puntarenae and Themiste (T.) hennahi; four species are similar to nominal species: Sipunculus (S.) cf. polymyotus, Siphonosoma cf. vastum, Siphonosoma cf. cumanense and Phascolosoma (P.) cf. perlucens; and two new species are described: Aspidosiphon (Paraspidosiphon) cutleri sp. nov. and Aspidosiphon (Paraspidosiphon) pastori sp. nov. A checklist and an identification key for all sipunculan species from the TEP are presented. The checklist includes 53 taxa, 25 of which are questionable records. This work generated 11 new records of sipunculans in the SMP and five new records in the TEP.
A taxonomic study on the Afrotropical genera Afrepipona Giordani Soika, 1965 and Afrepsilon gen. nov. is presented. Twenty new species are described, of which 15 are in Afrepipona (Afrepipona anomala sp. nov., Afrepipona cellularis sp. nov., Afrepipona clonata sp. nov., Afrepipona cuprea sp. nov., Afrepipona lamellata sp. nov., Afrepipona lamptula sp. nov., Afrepipona lobulata sp. nov., Afrepipona meridionalis sp. nov., Afrepipona occidentalis sp. nov., Afrepipona orientalis sp. nov., Afrepipona punctatissima sp. nov., Afrepipona scabra sp. nov., Afrepipona segregata sp. nov., Afrepipona ulterior sp. nov., Afrepipona vulcanica sp. nov.) and five are in Afrepsilon (Afrepsilon aterrimum gen. et sp. nov., Afrepsilon ferrugineoaureum gen. et sp. nov., Afrepsilon hybridum gen. et sp. nov., Afrepsilon minor gen. et sp. nov., and Afrepsilon pictum gen. et sp. nov.). Afrepipona lamptoensis Giordani Soika, 1965 is withdrawn from synonymy with A. angusta (de Saussure, 1863) and subsequently revalidated. Afrepipona unifasciata Gusenleitner, 2012 is transferred to the genus Antodynerus de Saussure, 1855 (Antodynerus unifasciatus comb. nov.). Keys to all known species are provided.
Description of four new species of the Neotropical genus Scione Walker, 1850 (Diptera: Tabanidae)
(2024)
After 94 years after the last revision of the genus and after 22 years since the last species was named, we describe four new species of Scione from Ecuador and Peru: S. cooperi sp. nov., S. gertrudeae sp. nov., S. kroeberi sp. nov. and S. merianae sp. nov. We provide diagnoses, descriptions, photographs and discussions for each of the species.
Regelmäßig werden Debatten um Geschlecht geführt, auch mit dem Fokus auf Schule. So regt die PISA-Studie mit ihren Ergebnissen im Jahr 2000 einen Diskurs um Bildungserfolg und Geschlecht an. Jürgen Budde (2009) vermutet beispielsweise einen engen Zusammenhang vom Schulerfolg eines Jungen mit der jeweiligen Schulkultur und konstatiert in diesem Zusammenhang eine Forschungslücke. Die Studie zu GeschlechterSchulKulturen schließt hier in Bezug auf eine Beforschung von Schulkultur mit Fokus auf Geschlechter an.
Anhand eines gegenstandsverankerten Vorgehens in Form einer Kombination von ethnographischem Forschungsstil und Grounded Theory Methodologie werden Interaktionen und verbale Zuschreibungen im Arrangement zweier integrierter Gesamt- und Ganztagsschulen beforscht. Dabei liegen folgende Forschungsfragen zugrunde: Welche Geschlechterkonstruktionen lassen sich am Beispiel zweier Gesamt- und Ganztagsschulen rekonstruieren? Lassen sich über Geschlechterkonstruktionen im schulischen Kontext spezifische GeschlechterSchulKulturen analytisch fassen und unterscheiden sich die beiden Forschungsfelder darin? Im Rahmen dieser Fragestellungen steht insbesondere die Frage danach im Fokus, welche Geschlechterkonstruktionen die Schüler*innen fünfter Klassen selbst vornehmen. Denn den öffentlichen Diskurs um die Ausbildung von Geschlechtsidentität führen Erwachsene, aber wie konstruieren die Schüler*innen Geschlechtlichkeit in ihrem Schulalltag? Welche Geschlechterzuschreibungen nehmen sie vor und welche möglichen Zusammenhänge lassen sich mit den jeweiligen Schulen rekonstruieren?
In der Studie zu GeschlechterSchulKulturen werden verbale Schüler*innen-Zuschreibungen in den Blick genommen, die in einem zweiten Schritt über einen Vergleich der beiden beforschten Schulen betrachtet und darauf folgend mit den jeweiligen Geschlechter(vor)strukturierungen der Schulen kontextualisiert werden, um damit dem Begriff GeschlechterSchulKulturen analytisch auf die Spur zu kommen. Die Studie liefert dabei zahlreiche Einblicke in verbale Schüler*innen-Zuschreibungen. Daran schließt eine Erörterung möglicher Implikationen für die schulische Praxis an. Dabei liefert die Studie zu GeschlechterSchulKulturen Annahmen zu spezifischen schulischen Kulturen, die bestimmte Konstruktionsprozesse gegebenenfalls (be)fördern. Mit der Studie zu GeschlechterSchulKulturen werden zudem methodologische Fragen zu schulischer Geschlechterforschung bearbeitet und ein Beitrag zu der Darstellbarkeit reflexiver Forschung geleistet.
Correlative dynamic imaging of cellular landmarks, such as nuclei and nucleoli, cell membranes, nuclear envelope and lipid droplets is critical for systems cell biology and drug discovery, but challenging to achieve with molecular labels. Virtual staining of label-free images with deep neural networks is an emerging solution for correlative dynamic imaging. Multiplexed imaging of cellular landmarks from scattered light and subsequent demultiplexing with virtual staining leaves the light spectrum for imaging additional molecular reporters, photomanipulation, or other tasks. Current approaches for virtual staining of landmark organelles are fragile in the presence of nuisance variations in imaging, culture conditions, and cell types. We report training protocols for virtual staining of nuclei and membranes robust to variations in imaging parameters, cell states, and cell types. We describe a flexible and scalable convolutional architecture, UNeXt2, for supervised training and self-supervised pre-training. The strategies we report here enable robust virtual staining of nuclei and cell membranes in multiple cell types, including human cell lines, neuromasts of zebrafish and stem cell (iPSC)-derived neurons, across a range of imaging conditions. We assess the models by comparing the intensity, segmentations, and application-specific measurements obtained from virtually stained and experimentally stained nuclei and cell membranes. The models rescue missing labels, non-uniform expression of labels, and photobleaching. We share three pre-trained models (VSCyto3D, VSNeuromast, and VSCyto2D) and a PyTorch-based pipeline (VisCy) for training, inference, and deployment that leverages current community standards for image data and metadata.
Snapshots of acetyl-CoA synthesis, the final step of CO₂ fixation in the Wood-Ljungdahl pathway
(2024)
In the ancient microbial Wood-Ljungdahl pathway, CO2 is fixed in a multi-step process with acetyl-CoA synthesis at the bifunctional carbon monoxide dehydrogenase/acetyl-CoA synthase complex (CODH/ACS). Here, we present catalytic snapshots of the CODH/ACS from the gas-converting acetogen Clostridium autoethanogenum, characterizing the molecular choreography of the overall reaction including electron transfer to the CODH for CO2 reduction, methyl transfer from the corrinoid iron-sulfur protein (CoFeSP) partner to the ACS active site and acetyl-CoA production. Unlike CODH, the multidomain ACS undergoes large conformational changes to form an internal connection to the CODH active site, accommodate the CoFeSP for methyl transfer and protect the reaction intermediates. Altogether, the structures allow us to draw a detailed reaction mechanism of this enzyme crucial for CO2 fixation in anaerobic organisms.
Members of the arginine–serine-rich protein family (SR proteins) are multifunctional RNA-binding proteins that have emerged as key determinants for mRNP formation, identity and fate. They bind to pre-mRNAs early during transcription in the nucleus and accompany bound transcripts until they are translated or degraded in the cytoplasm. SR proteins are mostly known for their essential roles in constitutive splicing and as regulators of alternative splicing. However, many additional activities of individual SR proteins, beyond splicing, have been reported in recent years. We will summarize the different functions of SR proteins and discuss how multifunctionality can be achieved. We will also highlight the difficulties of studying highly versatile SR proteins and propose approaches to disentangle their activities, which is transferrable to other multifunctional RBPs.
Cell-free (CF) synthesis with highly productive E. coli lysates is a convenient method to produce labeled proteins for NMR studies. Despite reduced metabolic activity in CF lysates, a certain scrambling of supplied isotope labels is still notable. Most problematic are conversions of 15N labels of the amino acids L-Asp, L-Asn, L-Gln, L-Glu and L-Ala, resulting in ambiguous NMR signals as well as in label dilution. Specific inhibitor cocktails suppress most undesired conversion reactions, while limited availability and potential side effects on CF system productivity need to be considered. As alternative route to address NMR label conversion in CF systems, we describe the generation of optimized E. coli lysates with reduced amino acid scrambling activity. Our strategy is based on the proteome blueprint of standardized CF S30 lysates of the E. coli strain A19. Identified lysate enzymes with suspected amino acid scrambling activity were eliminated by engineering corresponding single and cumulative chromosomal mutations in A19. CF lysates prepared from the mutants were analyzed for their CF protein synthesis efficiency and for residual scrambling activity. The A19 derivative “Stablelabel” containing the cumulative mutations asnA, ansA/B, glnA, aspC and ilvE yielded the most useful CF S30 lysates. We demonstrate the optimized NMR spectral complexity of selectively labeled proteins CF synthesized in “Stablelabel” lysates. By taking advantage of ilvE deletion in "Stablelabel", we further exemplify a new strategy for methyl group specific labeling of membrane proteins with the proton pump proteorhodopsin.
Measurements of vertical velocity from vertically pointing Doppler lidars are used to derive the profiles of vertical velocity variance. Observations were taken during the FESSTVaL (Field Experiment on Submesoscale Spatio-Temporal Variability in Lindenberg) campaign during the warm seasons of 2020 and 2021. Normalized by the square of convective velocity scale, the average vertical velocity variance profile follows the universal profile of Lenschow et al. (1980), however, daily profiles still show a high day-to-day variability. We found that moisture transport and the content of moisture in the boundary layer could explain the remaining variability of the normalized vertical velocity variance. The magnitude of the normalized vertical velocity variance is highest on clear-sky days, and decreases as the relative humidity increase and surface latent heat flux decrease in cloud-topped and rainy days. This suggests that moisture content and moisture transport are limiting factors for the intensity of turbulence in the convective boundary layer. We also found that the intensity of turbulence decreases with an increase in boundary layer cloud fraction during FESSTVaL, while the latent heating in the cloud layer was not a relevant source of turbulence in this case. We conclude that a new vertical velocity scale has to be defined that would take into account the moist processes in the convective boundary layer.
Measurements of vertical velocity from vertically pointing Doppler lidars are used to derive the profiles of normalized vertical velocity variance. Observations were taken during the FESSTVaL (Field Experiment on Submesoscale Spatio-Temporal Variability in Lindenberg) campaign during the warm seasons of 2020 and 2021. Normalized by the square of the convective velocity scale, the average vertical velocity variance profile follows the universal profile of Lenschow et al. (1980). However, daily profiles still show a high day-to-day variability. We found that moisture transport and the content of moisture in the boundary layer could explain the remaining variability of the normalized vertical velocity variance. The magnitude of the normalized vertical velocity variance is highest on clear-sky days and decreases as the absolute humidity increases and surface latent heat flux decreases on cloud-topped days. This suggests that moisture content and moisture transport are limiting factors for the intensity of turbulence in the convective boundary layer. We also found that the intensity of turbulence decreases with an increase in the boundary layer cloud fraction during FESSTVaL, while the latent heating in the cloud layer was not a relevant source of turbulence in this case. We conclude that a new vertical velocity scale has to be defined that would take into account the moist processes in the convective boundary layer.
Ziel der vorliegenden Untersuchung war es, die Analytik der Neurotransmitterbestimmung im Liquor zu etablieren und in das vorhandene Leistungsspektrum des Stoffwechsellabors zu integrieren. Die klinische Ausrichtung gilt sowohl der Detektion primärer Neurotransmitterdefekte als auch der Untersuchung der Ursachen und Auswirkungen sekundärer Neurotransmitterstörungen.
Die Messung der Biogenen Amine im Liquor mittels der Hochdruck-Flüssigkeits-Chromatographie in dem hier vorgestellten Verfahren konnte standardisiert und in das vorhandene Leistungsspektrum des Stoffwechsellabors des Zentrums für Kinderheilkunde und Jugendmedizin der J.W. Goethe-Universität, Frankfurt etabliert werden. Es ist nachgewiesenermaßen sensitiv, spezifisch und erlaubt eine schnelle und reproduzierbare Analyse bei minimaler Probenmenge und Probenaufarbeitung.
Meßtechnisch konnte durch den von unserer Arbeitsgruppe verwendeten ESA CoulArray® Detektor (Modell 5600) (im Gegensatz zu den bisher beschriebenen amperometrischen Detektoren) aufgrund seiner 16 einzelnen coulometrischen Sensoren eine enorme Verbesserung der Nachweisqualität der untersuchten Neurotransmittersubstanzen erreicht werden. Aufgrund verschiedener Potentialfelder ist eine spezifische Detektion über einen weiten Einsatzbereich aufgrund der elektrochemischen Unterschiede zu erzielen. Dies ermöglicht eine wesentlich größere Anzahl zu detektierender Substanzen eindeutig zu identifizieren und erlaubt damit nicht nur die eindeutige Zuordnung der zu messenden Endabbauprodukte HVA und 5HIAA, sondern auch des gesamten Spektrums der vorgeschalteten Metabolite. Somit ließ sich mit diesem aufgebauten Analysesystem die komplexe vollständige Abbildung des Stoffwechselwegs der zentralen biogenen Amine verwirklichen.
Die sehr sensible Messung der Parameter stellt große Anforderung an
Probengewinnung, Probenverarbeitung und Meßanalyse. Aufgrund der
Durchführung interner Qualitäskontrolluntersuchungen konnte der Nachweis einer sicheren reproduzierbaren Analytik erbracht werden. Insbesondere die Notwendigkeit der ausreichenden Unterdrückung der weiter ablaufenden chemischen Prozesse durch die unmittelbare Kühlung der Liquorproben auf eine Temperatur von -80°C wurde nachgewiesen. Zusätzlich konnte gezeigt werden, dass die Verwendung von handelsüblichen EDTA-Röhrchen einen ausreichenden antioxidativen Schutz bietet und wir somit eine anwenderfreundliche Probengewinnung empfehlen können. Die strikte Einhaltung des Protokolls zur Gewinnung und weiteren Verarbeitung der Liquorproben ist elementar und stellt insbesondere bei zur Zeit noch bestehenden uneinheitlichen altersabhängigen Referenzwerten die Grundlage zur diagnostischen Bewertung der gemessenen Werte dar. Eine Standardisierung der Referenzwerte auf internationaler Ebene ist unverzichtbar zur korrekten Interpretation der gemessenen Daten und sollte vorrangiges Streben aller beteiligten Laboratorien sein. Ein entsprechender Antrag auf ein erneutes, jährlich stattfindendes externes Qualitätskontrollprogramm (Ringversuch) wurde gestellt.
Mit der Bestimmung der Biogenen Amine im Liquor steht ein potentes Instrument zur Detektion pädiatrischer Neurotransmittererkrankungen zur Verfügung. Es gibt weltweit jedoch nur eine geringe Anzahl von Laboratorien mit diesem Analyseangebot. Somit trägt die Etablierung dieser Analytik im vorhandenen Leistungsspektrum des Stoffwechsellabors des Zentrums für Kinderheilkunde und Jugendmedizin der J.W. Goethe-Universität, Frankfurt dazu bei diese Lücke zu schließen. In der Mehrzahl sind Erkrankungen der zentralen Biogenen Amine ausschließlich nur über eine Messung der Metaboliten im Liquor diagnostizierbar, nur wenige angeborene Neurotransmitterdefekte fallen durch periphere Serumparameter, wie z.B. einer Hyperphenylalaninämie auf. Es ergibt sich der Verdacht, dass diese Erkrankungsformen unterdiagnostiziert sind und auch das Wissen um diese Erkrankungen nicht allgemein vorausgesetzt werden kann.
Mit den Neurotransmittervorstufen (z.B. L-Dopa oder 5OH-Tryptophan) steht betroffenen Patienten eine adäquate Therapieoption zur Verfügung, so dass die Aufdeckung eines spezifischen Defektes in der Synthese der Biogenen Amine vorrangiges Ziel sein müsste. Exemplarisch für die beeindruckende Effektivität der Therapie mittels L-Dopa und 5OH-Tryptophan sei auf den Erfahrungsbericht des von unserer Arbeitsgruppe betreuten Patienten mit 6-PTPS-Defekt verwiesen.
Zusätzlich konnte mit dieser Arbeit gezeigt werden, dass die wiederholenden Messungen dem Therapiemonitoring dienen und eine unverzichtbare Grundlage der individuellen Therapie betroffener Patienten darstellen. Sekundäre Veränderungen der Neurotransmission sind beschrieben, jedoch fehlen weitergehende Untersuchungen zur Einordnung ihrer klinischen Relevanz. Gerade diese große inhomogene Patientengruppe stellt eine zukünftige Herausforderung für weitere wissenschaftliche Anstrengungen in diesem Bereich dar. Wie anhand des Beispiels der Patienten mit mitochondrialer Enzephalopathie dargestellt, kann die vorhandene Analysemethode dazu beitragen das Wissen um die Pathophysiologie bekannter Erkrankungen zu erweitern. Da analog zu den primären Erkrankungen auch hier Therapieoptionen zur Verfügung stehen würden, ist es dringend notwendig die übliche Liquordiagnostik diesbezüglich auszudehnen. Aufgrund der auch im Rahmen dieser Arbeit erhobenen Daten kann gefolgert werden bei ungeklärten neuropädiatrischen Erkrankungen, besonders jenen, welche in der Neonatal- oder frühen Säuglingszeit beginnen und progredient verlaufen, und sich klinisch durch Dyskinesien, Krampfanfälle und Enzephalopathien äußern, eine Liquoruntersuchung auf Biogene Amine zu veranlassen.
Somit dient die erbrachte Arbeit zur Etablierung der Analytik der Neurotransmitterbestimmung im Liquor dem Erkenntnisgewinn neuer metabolischer Erkrankungen, erweitert das Grundlagenwissen bekannter Störungen und dient der Detektion seltener, jedoch oft schwerwiegender Erkrankungen.
In der vorliegenden Arbeit präsentieren wir die Daten von perkutanen Interventionen im Bereich der Beckenstrombahn, welche retrospektiv der Klassifikation der Transatlantic Society Consensus Gruppe (TASC) folgend als TASC C und D kategorisiert wurden. Für TASC D Läsionen wurde von der TASC Gruppe die chirurgische Therapie empfohlen. Für TASC C Läsionen konnte mangels aussagekräftiger Daten keine konkrete Empfehlung bezüglich einer chirurgischen oder interventionellen Behandlung ausgesprochen werden und man berief sich auf die nach wie vor weit verbreitete Anwendung gefäßchirurgischer operativer Therapie im Fall dieser Läsionen.
Ziel dieser Arbeit war es, herauszuarbeiten, ob bei Behandlung von Gefäßläsionen dieser beiden Klassifikationen mit perkutaner transluminaler Angioplastie akzeptable Erfolgs- und Offenheitsraten erreicht werden können und ob eine Empfehlung zu Gunsten der interventionellen Therapie ausgesprochen werden kann.
In einem Zeitraum von Januar 2000 bis Dezember 2002 wurden an unserem Institut 253 Patienten mit 294 Läsionen im Bereich der Beckenarterien interventionell behandelt. Unter ihnen befanden sich 89 Patienten mit 129 klassifizierten TASC C und D Läsionen, 110 Stenosen (65 in der AIC und 45 in der AIE) und 19 Okklusionen (12 in der AIC und 7 in der AIE). Die durchschnittliche Länge der Läsion betrug 49,2±31,2 mm. Zum Einsatz kamen 148 Stents. Der technische Erfolg der Interventionen betrug 96,9%. Komplikationen traten bei 5,6% der Patienten auf, wobei wir in keinem dieser Fälle eine periphere Embolie verzeichneten. Die Nachbehandlung erfolgte über einen Zeitraum von 12-38 Monate, durchschnittlich 25 Monate. Nachuntersuchungen umfassten eine klinische Untersuchung, die Messung des Tibial-Brachialen-Quotienten und eine Duplex-Sonographie am ersten Tag postinterventionell, nach 1, 3, 6 und 12 Monaten und anschließend einmal jährlich.
Aus den Nachuntersuchungen ergab sich gemessen an den Kriterien der AHA ein klinischer Erfolg bei 97,3% der TASC C Patienten und 88,5% der Patienten mit TASC D Läsionen. Im Verlauf der Nachbeobachtungszeit kam es zu 6 Restenosen und einer Reokklusion im behandelten Gefäßsegment, von denen 4 erfolgreich mit Hilfe einer zweiten Intervention therapiert werden konnten. Bei 3 Patienten bedurfte es operativer Eingriffe in Form zweier aortoiliakaler Bypässe und einer Unterschenkelamputation.
Es ergab sich somit nach durchschnittlich 25 Monaten eine primäre Offenheitsrate von 89,9% und eine sekundäre Offenheitsrate von 95,5%. Die von uns präsentierten Daten sind mit den nach Behandlung fokaler, kurzstreckiger (<10 cm) Stenosen publizierten Daten vergleichbar.
Die Ergebnisse dieser Studie zeigen, dass die perkutane Rekanalisation sowohl im Falle der TASC C als auch der TASC D Läsionen mit hohem technischen und hohem klinischen Erfolg, einer niedrigen Komplikationsrate und viel versprechenden Offenheitsraten durchgeführt werden kann. Interventionelle Therapie kann somit durchaus auch für die Behandlung von Läsionen der Klassifikation TASC C und D empfohlen werden.
Bei einer fortgeschrittenen oro-vestibulären Alveolarfortsatzatrophie, die durch einen länger zurückliegenden Zahnverlust, Zahntrauma oder Entzündung bedingt ist, ist die Indikation zu einer Implantation häufig ohne zusätzliche Aufbaumaßnahmen des Alveolarkammes nicht möglich. Osteoplastische Verfahren, die der transversalen Kieferkammerweiterung dienen, können in diesen anatomisch schwierigen Ausgangsbedingungen zur Anwendung kommen.
Die vorliegende Studie sollte die Ergebnisse nach Anwendung eines minimal invasiven chirurgischen Verfahrens (Bone-spreading) mit Hilfe eines speziellen Instrumentensystems bewerten.
Über einen Zeitraum von 8 Jahren wurden bei 53 Patienten (24 Männern, 29 Frauen), die ein primär unzureichendes transversales Knochenangebot aufwiesen, 129 Implantate simultan mit der Bone-spreading-Technik inseriert. Die mittlere Liegedauer der Implantate betrug 3,81 Jahre. Zum Zeitpunkt der letzten Nachuntersuchung standen die Implantate durchschnittlich 3,39 Jahre unter funktioneller Belastung. Die Verteilung der inserierten Implantate erstreckte sich sowohl auf den Oberkiefer (57,36 % der Implantate) als auch den Unterkiefer (42,64 % der Implantate). Die prothetischen Versorgungen der 129 Implantate wurden mit 71 Implantaten als Krone, mit 44 als Brücke und mit jeweils 7 Implantaten als Konus- und Resilienzteleskope zementiert.
Die klinischen Daten (modifizierter Plaque-Index, modifizierter Sulcus-Blutungs-Index, Sondierungstiefe mesial und vestibulär, periimplantäre Mucosa, Breite der Gingiva propria, klinische Mobilität, Periotestwert) und die radiologischen Befunde (horizontaler und vertikaler Knochenabbau) wurden im Rahmen von jährlichen Recalluntersuchungen erhoben und analysiert.
Die Werte der Entzündungs-Indizes waren im allgemeinem stabil. So konnte bei 88 % der Patienten bei der letzten Nachuntersuchung kein höherer Wert von Plaqueindex als 1 (= nicht sichtbar, hauchdünner Belag) beobachtet werden. Auch der Sulcus-Blutungs-Index war zufriedenstellend. Hier wiesen 91 % der Patienten bei der letzten Nachuntersuchung keine Blutung bzw. nur einen Blutungspunkt, aber keine Farbveränderung oder Schwellung der Gingiva auf. Ähnlich verhielten sich die Werte der Sondierungstiefen. Diese Ergebnisse
spiegelten sich in den stabilen periimplantären Verhältnisse wider, die bei 93,81 % der Probanden bei der letzten Nachuntersuchung vorgefunden wurden. Die gemessenen Periotestwerte entsprachen denen eines osseointegrierten Implantates. Sie lagen bei der letzten Nachuntersuchung im Schnitt bei –2,7. Der radiologisch ermittelte periimplantäre Knochenabbau war bei den hier inserierten Implantaten nicht größer als 0,2 mm pro Jahr. So konnte bei 85,27 % der unter Funktion stehenden Implantate kein bzw. nur ein minimaler horizontaler Knochenabbau vorgefunden werden, bei weiteren 13,95 % ging der horizontale Knochenabbau nicht über ein Viertel der Implantatlänge hinaus. Ähnlich verhielt sich der vertikale Knochenabbau. Kein bzw. nur ein minimaler Knochenabbau war bei 59,06 % der Patienten, ein bis zu einem Viertel bei 39,09 % vorzufinden. Ein Implantatverlust ist während der gesamten Beobachtungszeit nicht eingetreten. Das entsprach einer Überlebensrate von 100%.
Die bisherige Untersuchung über 8 Jahre zeigte, daß die orale Rehabilitation mit osseointegrierten Implantaten unter Anwendung der Bone-spreading-Methode sowohl bei einem transversalen Knochenangebot ab einer Alveolarfortsatzbreite von 3 mm als auch in den Knochenklassen D1 und D2, die vornehmlich im Unterkiefer vorzufinden sind, erfolgreich ist.
Highlights
• Linking ecological and ecotoxicological data from 30 river sites.
• Bioassays indicate complex mixture of chemicals with different modes of action.
• Macroinvertebrate community deteriorates along a toxicity gradient.
• Macroinvertebrate response has low potential for toxicity-specific bioindicators.
• Effect-based methods could isolate toxicity effects from multiple stressors.
Abstract
Chemical pollution is one of the most important threats to freshwater ecosystems. The plethora of potentially occurring chemicals and their effects in complex mixtures challenge standard monitoring methods. Effect-based methods (EBMs) are proposed as complementary tools for the assessment of chemical pollution and toxic effects. To investigate the effects of chemical pollution, the ecological relevance of EBMs and the potential of macroinvertebrates as toxicity-specific bioindicators, ecological and ecotoxicological data were linked. Baseline toxicity, mutagenicity, dioxin-like and estrogenic activity of water and sediment samples from 30 river sites in central Germany were quantified with four in vitro bioassays. The responses of macroinvertebrate communities at these sites were assessed by calculating 16 taxonomic and functional metrics and by investigating changes in the taxonomic and trait composition. Principal component analysis revealed an increase in toxicity along a joint gradient of chemicals with different modes of action. This toxicity gradient was associated with a decrease in biodiversity and ecological quality, as well as significant changes in taxonomic and functional composition. The strength of the effects suggested a strong impact of chemical pollution and underlined the suitability of EBMs in detecting ecological relevant effects. However, the metrics, taxa, and traits associated with vulnerability or tolerance to toxicity were found to also respond to other stressors in previous studies and thus may have only a low potential as toxicity-specific bioindicators. Because macroinvertebrates respond integratively to all present stressors, linking both ecological and environmental monitoring is necessary to investigate the overall effects but also isolate individual stressors. EBMs have a high potential to separate the toxicity of chemical mixtures from other stressors in a multiple stressor scenario, as well as identifying the presence of chemical groups with specific modes of action.
We investigate the early time dynamics of heavy ion collisions studying the time evolution of the energy-momentum tensor as well as energy-momentum correlations within a uniformly thermalizing holographic QGP. From these quantities, we suggest a far-from equilibrium definition of shear viscosity, which is a crucial property of QCD matter as it significantly determines the generation of elliptic flow already at early times. During an exemplary initial heating phase of the holographic QGP the shear viscosity of entropy density ratio decreases down to 60%, followed by an overshoot to 110% of the near-equilibrium value, η/s=1/(4π). Implications for the QCD QGP are discussed. Subsequently, we consider a holographic QGP which is Bjorken-expanding. Its energy-momentum tensor components have a known hydrodynamic attractor to which all time evolutions collapse independent of the initial conditions. Based on this, we propose a definition for a far from equilibrium speed of sound, and analytically compute its hydrodynamic attractor. Subjecting this Bjorken-expanding plasma to an external magnetic field and an axial chemical potential, we study the chiral magnetic effect far from equilibrium.
We investigate the early time dynamics of heavy ion collisions studying the time evolution of the energy-momentum tensor as well as energy-momentum correlations within a uniformly thermalizing holographic QGP. From these quantities, we suggest a far-from equilibrium definition of shear viscosity, which is a crucial property of QCD matter as it significantly determines the generation of elliptic flow already at early times. During an exemplary initial heating phase of the holographic QGP the shear viscosity of entropy density ratio decreases down to 60%, followed by an overshoot to 110% of the near-equilibrium value, η/s=1/(4π). Implications for the QCD QGP are discussed. Subsequently, we consider a holographic QGP which is Bjorken-expanding. Its energy-momentum tensor components have a known hydrodynamic attractor to which all time evolutions collapse independent of the initial conditions. Based on this, we propose a definition for a far from equilibrium speed of sound, and analytically compute its hydrodynamic attractor. Subjecting this Bjorken-expanding plasma to an external magnetic field and an axial chemical potential, we study the chiral magnetic effect far from equilibrium.
Heavy quarks are useful probes to investigate the properties of the Quark-Gluon Plasma (QGP) produced in heavy-ion collisions at the LHC, since they are produced in initial hard scattering processes. To single out the signals that are characteristic of the QGP, it is nevertheless crucial to understand the primordial heavy-quark production in vacuum, and to disentangle hot from cold nuclear matter effects. Moreover, observations of collective effects in high-multiplicity pp and p-Pb collisions show surprising similarities with those in heavy-ion collisions. Heavy-flavour production in such collisions could give further insight into the underlying processes. The heavy-flavour production can be studied with e+e− pairs from correlated semileptonic decays of heavy-flavour hadrons. Compared to single heavy-flavour measurements, the dielectron yield contains information about the initial kinematical correlations between the charm and anti-charm quarks, which is otherwise not accessible, and is sensitive to soft heavy-flavour production. We report results on correlated e+e− pairs in pp collisions recorded by the ALICE detector at different collision energies. The production of heavy quarks is discussed by comparing the yield of dielectrons from heavy-flavour hadron decays as a function of invariant mass, pair transverse momentum and distance of closest approach to the primary vertex with different Monte Carlo event generators. The heavy-flavour production cross sections are also presented. Results from high-multiplicity pp collisions at √s=13 TeV and the status of the p-Pb analysis at √sNN=5.02 TeV are reported as well.
Das Buch beforscht, wie der Eintritt von Juden und Jüdinnen in die moderne Gesellschaft Wiens "als Theater" und mit theatralen Mitteln stattfand und entwirft so eine Praxeologie jüdischer Zugehörigkeit und Differenz. In vier Studien werden jüdische Erfahrungen der Moderne zwischen Zeigen und Beobachten, sozialer Schau und antisemitischer Bedrängnis als Modi des Theatralen zum Thema. Dabei rückt Theater als Praxis ins Zentrum, mit der Zugehörigkeit in der Moderne verhandelt, selbstbewusst behauptet oder befragt wurde. Während sich Juden und Jüdinnen "wie auf einer Bühne" permanenter Beobachtung ausgesetzt sahen, kommentierten sie dies wiederum theatral, erprobten eigene Strategien sozialer Teilhabe und beteiligten sich an der Ausgestaltung von bürgerlichen Sozialrollen in der Großstadt. Theater zeigt sich so als vielschichtige kulturelle Praxis wie als "Spiel- und Spiegelform des Lebens" (Stefan Zweig).
Heavy quarks are useful probes to investigate the properties of the Quark-Gluon Plasma (QGP) produced in heavy-ion collisions at the LHC, since they are produced in initial hard scattering processes. To single out the signals that are characteristic of the QGP, it is nevertheless crucial to understand the primordial heavy-quark production in vacuum, and to disentangle hot from cold nuclear matter effects. Moreover, observations of collective effects in high-multiplicity pp and p-Pb collisions show surprising similarities with those in heavy-ion collisions. Heavy-flavour production in such collisions could give further insight into the underlying processes. The heavy-flavour production can be studied with e+e− pairs from correlated semileptonic decays of heavy-flavour hadrons. Compared to single heavy-flavour measurements, the dielectron yield contains information about the initial kinematical correlations between the charm and anti-charm quarks, which is otherwise not accessible, and is sensitive to soft heavy-flavour production. We report results on correlated e+e− pairs in pp collisions recorded by the ALICE detector at different collision energies. The production of heavy quarks is discussed by comparing the yield of dielectrons from heavy-flavour hadron decays as a function of invariant mass, pair transverse momentum and distance of closest approach to the primary vertex with different Monte Carlo event generators. The heavy-flavour production cross sections are also presented. Results from high-multiplicity pp collisions at √s=13 TeV and the status of the p-Pb analysis at √sNN=5.02 TeV are reported as well.
Heavy quarks are useful probes to investigate the properties of the Quark-Gluon Plasma (QGP) produced in heavy-ion collisions at the LHC, since they are produced in initial hard scattering processes. To single out the signals that are characteristic of the QGP, it is nevertheless crucial to understand the primordial heavy-quark production in vacuum, and to disentangle hot from cold nuclear matter effects. Moreover, observations of collective effects in high-multiplicity pp and p-Pb collisions show surprising similarities with those in heavy-ion collisions. Heavy-flavour production in such collisions could give further insight into the underlying processes. The heavy-flavour production can be studied with e+e− pairs from correlated semileptonic decays of heavy-flavour hadrons. Compared to single heavy-flavour measurements, the dielectron yield contains information about the initial kinematical correlations between the charm and anti-charm quarks, which is otherwise not accessible, and is sensitive to soft heavy-flavour production. We report results on correlated e+e− pairs in pp collisions recorded by the ALICE detector at different collision energies. The production of heavy quarks is discussed by comparing the yield of dielectrons from heavy-flavour hadron decays as a function of invariant mass, pair transverse momentum and distance of closest approach to the primary vertex with different Monte Carlo event generators. The heavy-flavour production cross sections are also presented. Results from high-multiplicity pp collisions at √s=13 TeV and the status of the p-Pb analysis at √sNN=5.02 TeV are reported as well.
Electromagnetic probes such as photons and dielectrons (e+e− pairs) are a unique tool to study the space-time evolution of the hot and dense matter created in ultrarelativistic heavy-ion collisions. At low dielectron invariant mass (mee), thermal radiation from the hot hadronic phase contributes to the dielectron spectrum via decays of ρ mesons, whose spectral function is sensitive to chiral-symmetry restoration. At larger mee, thermal radiation from the quark–gluon plasma carries information about the early temperature of the medium. At LHC energies, it is nevertheless dominated by a large background from correlated heavy-flavor hadron decays affected by energy loss and flow in the medium. Complementary to the real photon measurements, dielectron data also allow the extraction of the real direct photon fraction, including thermal photons at low pair transverse momentum pT,ee. The latest ALICE results on dielectron studies in Pb-Pb, and in inelastic and high-multiplicity pp collisions, at √sNN = 5.02 TeV and at √s = 13 TeV, respectively, are presented and compared to simulations and expectations from theory. The status of the Run 3 analysis is also reported.
The production yields of antideuterons and antiprotons are measured in pp collisions at a center-of-mass energy of √s=13 TeV, as a function of transverse momentum (pT) and rapidity (y), for the first time up to |y|=0.7. The measured spectra are used to study the pT and rapidity dependence of the coalescence parameter B2, which quantifies the coalescence probability of antideuterons. The pT and rapidity dependence of the obtained B2 is extrapolated for pT>1.7 GeV/c and |y|>0.7 using the phenomenological antideuteron production model implemented in PYTHIA 8.3 as well as a baryon coalescence afterburner model based on EPOS 3. Such measurements are of interest to the astrophysics community, since they can be used for the calculation of the flux of antinuclei from cosmic rays, in combination with coalescence models.
Measurement of beauty production via non-prompt charm hadrons in p-Pb collisions at √sNN = 5.02 TeV
(2024)
The production cross sections of D0, D+, and Λ+c hadrons originating from beauty-hadron decays (i.e. non-prompt) were measured for the first time at midrapidity in proton−lead (p−Pb) collisions at the center-of-mass energy per nucleon pair of √sNN=5.02 TeV. Nuclear modification factors (RpPb) of non-prompt D0, D+, and Λ+c are calculated as a function of the transverse momentum (pT) to investigate the modification of the momentum spectra measured in p−Pb collisions with respect to those measured in proton−proton (pp) collisions at the same energy. The RpPb measurements are compatible with unity and with the measurements in the prompt charm sector, and do not show a significant pT dependence. The pT-integrated cross sections and pT-integrated RpPb of non-prompt D0 and D+ mesons are also computed by extrapolating the visible cross sections down to pT = 0. The non-prompt D-meson RpPb integrated over pT is compatible with unity and with model calculations implementing modification of the parton distribution functions of nucleons bound in nuclei with respect to free nucleons. The non-prompt Λ+c/D0 and D+/D0 production ratios are computed to investigate hadronisation mechanisms of beauty quarks into mesons and baryons. The measured ratios as a function of pT display a similar trend to that measured for charm hadrons in the same collision system.
Particle production as a function of charged-particle flattenicity in pp collisions at √s = 13 TeV
(2024)
This paper reports the first measurement of the transverse momentum (pT) spectra of primary charged pions, kaons, (anti)protons, and unidentified particles as a function of the charged-particle flattenicity in pp collisions at s√=13 TeV. Flattenicity is a novel event shape observable that is measured in the pseudorapidity intervals covered by the V0 detector, 2.8<η<5.1 and −3.7<η<−1.7. According to QCD-inspired phenomenological models, it shows sensitivity to multiparton interactions and is less affected by biases towards larger pT due to local multiplicity fluctuations in the V0 acceptance than multiplicity. The analysis is performed in minimum-bias (MB) as well as in high-multiplicity events up to pT=20 GeV/c. The event selection requires at least one charged particle produced in the pseudorapidity interval |η|<1. The measured pT distributions, average pT, kaon-to-pion and proton-to-pion particle ratios, presented in this paper, are compared to model calculations using PYTHIA 8 based on color strings and EPOS LHC. The modification of the pT-spectral shapes in low-flattenicity events that have large event activity with respect to those measured in MB events develops a pronounced peak at intermediate pT (2<pT<8 GeV/c), and approaches the vicinity of unity at higher pT. The results are qualitatively described by PYTHIA, and they show different behavior than those measured as a function of charged-particle multiplicity based on the V0M estimator.
Cross-predictability denotes the fact that some assets can predict other assets' returns. I propose a novel performance-based measure that disentangles the economic value of cross-predictability into two components: the predictive power of one asset's signal for other assets' returns (cross-predictive signals) and the amount of an asset's return explained by other assets' signals (cross-predicted returns). Empirically, the latter component dominates the former in the overall cross-prediction effects. In the crosssection, cross-predictability gravitates towards small firms that are strongly mispriced and difficult to arbitrage, while it becomes more difficult to cross-predict returns when market capitalization and book-to-market ratio rise.