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Wir haben uns mit der Leitfähigkeitsdynamik von Barium-Natrium-Niobat-Kristallen (BSN-Kristallen) auseinandergesetzt und haben verschiedene Untersuchungen zum Themenkreis Lyapunov-Exponenten anhand von experimentellen BSN-Zeitreihen durchgeführt. Als einen typischen größten Lyapunov-Exponenten von chaotischen BSN-Zuständen erhalten wir Werte in der Größenordnung von 0.1 / s. Der Maximalwert entspricht ca. 3.5 bits pro Attraktorumlauf. Wir beobachten für die Mehrzahl der chaotische BSN-Zustände entlang der unersuchten Ruelle-Takens-Newhouse-Route (RTN-Route) zwei positive Lyapunov-Exponenten mit einem schmalen Übergangsbereich in dem wir nur einen positiven Lyapunov-Exponenten erkennen. Diesen Befund interpretieren wir als eine kompleer werdende Dynamik mit wachsender Stromstärke durch den Kristall, die wir auch durch eine kompliziertere Attraktorstruktur der BSN-Zustände entlang der RTN-Route ins Chaos bestätigen können. Die Abschätzung von Lyapunov-Exponenten der BSN-Zustände entlang der RTN-Route bestätigen die meisten der Ergebnisse, die wir bisher mit anderen Verfahren erhalten haben. Die Kolmogorov-Entropie K1 die wir mit Gleichung (5) aus den positiven Lyapunov-Exponenten bestimmen, ist allerdings um etwa einen Faktor vier kleiner als Abschätzungen der Entropie K2, die sich aus Korrelationsbetrachtungen in vorangegangenen Untersuchungen ergeben haben. Durch die Untersuchungen zu lokalisierten Lyapunov-Exponenten erhalten wir eine detailliertere Beschreibung der BSN-Dynamik im rekonstruierten Ersatz-Phasenraum. Wir erkennen an verschiedenen Beispielen, daß die Attraktoren von BSN-Zuständen entlang der RTN-Route durch mindestens einen markanten Bereich mit großen positiven lokalisierten Lyapunov-Exponeten ausgezeichnet sind. Bezüglich der Variation der Attraktoren entlang der RTN-Route beobachten wir, wie sich bevorzugt diese Bereiche in ihrer Form verändern. Die chaotischen Zustände sind durch eine Attraktorregion ausgezeichnet, die einen sichtbar größeren lokalisierten Lyapunov-Exponenten besitzt, als die restlichen Gebiete. Wir führen diese Beobachtung auf das lokale Aufbrechen eines 2-Frequenz-Torus zurück und können diese Vermutung durch Untersuchungen zu einem chaotischen Zustand aus der RTN-Route belegen. Die Simulationsergebnisse zur BSN-Modellgleichung zeigen, daß die Gleichung innerhalb der untersuchten Parameterbereiche kein chaotisches Verhalten generiert. Die aus experimentellen Daten angepaßten Parametervektoren ->k deuten darauf hin, daß die Lösungen periodische Inseln in einer Fixpunktlandschaft darstellen. Mit den entwickelten Methoden zur Bestimmung von Lyapunov-Exponenten aus Delay-Differentialgleichungen stellen wir die Grundlage bereit, um zukünftige Untersuchungen an gekoppelten Modellgleichungen durchführen zu können.
In der vorliegenden Arbeit beschäftigen wir uns mit der Frage, wie ein Regler für ein hochdimensionales physikalisch/technisches System strukturiert und optimiert werden soll. Diesbezüglich untersuchen wir einen neuen Ansatz, welcher versucht, Regel-Mechanismen des ökonomischen Marktes und Lern-Prozesse mit in den Regler einzubauen. Um eine anschauliche Vorstellung von der Wirkung des Reglers zu erhalten, wenden wir diesen auf ein einfaches physikalisches Model an, eine an ihren Enden eingespannte eindimensionale Federkette. Wir implementieren das Model auf einem Rechner und simulieren den Einfluß des Regelverfahrens auf die Bewegung der Kette. Dabei beschränken wir uns auf den Grenzfall kleiner Amplituden, um das System im Rahmen einer näherungsweise linearen Dynamik beschreiben zu können. Mit Hilfe eines schwachen destabilisierenden Zusatzpotentials erreichen wir, daß die niedrigen Eigenmoden der schwingenden Kette instabil werden und die ausgestreckte Kette eine instabile Gleichgewichtslage darstellt. Wir stellen uns die Aufgabe, diese unter Verwendung des Reglers zu stabilisieren. Anhand des Modells untersuchen wir den Einfluß verschiedener Anfangsbedingungen der Kette, den Einfluß der Markt-Regelung, den Einfluß verschiedener Kommunikationsstrukturen und den Einfluß des Lernverfahrens auf die Wirksamkeit und die Robustheit des Regelprozesses. Als wichtigstes Ergebnis erkennen wir, daß die Regelung mit dem Markt robuster im Vergleich mit der Regelung ohne Markt ist, aber im allgemeinen einen höheren Regel-Energieaufwand aufweist. Untersuchungen anhand des Lernverfahrens ergeben, daß sich das Lernen der Markt- und der Kommunikationsstruktur kombinieren läßt und dadurch die Wirksamkeit der Regelung gegen über der Verwendung von nur einem der beiden Lern-Ansätze erhöht werden kann. Unsere Ergebnisse zeigen, daß sich das Markt-Konzept vollständig auf den gegebenen technischen Regelprozeß übertragen läßt. In der Diskussion der Ergebnisse führen wir die erhöhte Robustheit und den erhöhten Energieaufwand der Markt-Regelung auf eine indirekte, nichtlineare Kopplung der Regeleinheiten zurück, die der Markt-Mechanismus in den Regelprozeß einführt. Die Nichtlinearität bewirkt, daß die von dem Regler bestimmten Regelkräfte bei kleinen Kontrollfehlern relativ größer sind als bei großen Kontrollfehlern. Daduch ist der Energieaufwand der Markt-Regelung bei kleinen Kontrollfehlern gegenüber der Regelung ohne Markt erhöht. Der Regler ist damit in der Lage, die Kette auch bei dem Ausfall einer Regeleinheit zu stabilisieren, da ausreichend große Regelkräfte durch die verbleibenden Regeleinheiten ausgeübt werden. Die Kopplung von benachbarten Massenpunkten durch Federn unterstützt die Robustheit der Regelung in dem untersuchten Ketten-Modell, da die Kopplung dazu führt, daß die Massenpunkte eine zur instabilen Gleichgewichtslage rücktreibende Kraft erfahren und dadurch in den Bereich von kleinen Kontrollfehlern und relativ hohen Regelkräften gelangen. Am Ende der Diskussion gehen wir kurz auf mögliche Anwendungen der gewonnen Ergebnisse ein. Dabei haben wir besonders technische Regelprozesse im Sinne von Smart Matter (intelligente Bauteile) im Auge.
The chitinase-like protein YKL-40 was found to be increased in patients with severe asthma and chronic obstructive pulmonary disease (COPD), two disease conditions featuring neutrophilic infiltrates. Based on these studies and a previous report indicating that neutrophils secrete YKL-40, we hypothesized that YKL-40 plays a key role in cystic fibrosis (CF) lung disease, a prototypic neutrophilic disease. The aim of this study was (i) to analyze YKL-40 levels in human and murine CF lung disease and (ii) to investigate whether YKL-40 single-nucleotide polymorphisms (SNPs) modulate CF lung disease severity. YKL-40 protein levels were quantified in serum and sputum supernatants from CF patients and control individuals. Levels of the murine homologue BRP-39 were analyzed in airway fluids from CF-like βENaC-Tg mice. YKL-40SNPs were analyzed in CF patients. YKL-40 levels were increased in sputum supernatants and in serum from CF patients compared to healthy control individuals. Within CF patients, YKL-40 levels were higher in sputum than in serum. BRP-39 levels were increased in airways fluids from βENaC-Tg mice compared to wild-type littermates. In both CF patients and βENaC-Tg mice, YKL-40/BRP-39 airway levels correlated with the severity of pulmonary obstruction. Two YKL-40 SNPs (rs871799 and rs880633) were found to modulate age-adjusted lung function in CF patients. YKL-40/BRP-39 levelsare increased in human and murine CF airway fluids, correlate with pulmonary function and modulate CF lung disease severity genetically. These findings suggest YKL-40 as a potential biomarker in CF lung disease.
The Tarim River Basin, located in Xinjiang, NW China, is the largest endorheic river basin of China and one of the largest in whole Central Asia. Due to the extremely arid climate with an annual precipitation of less than 100 mm, the water supply along the Aksu and Tarim River solely depends on river water. This applies for anthropogenic activities (e.g. agriculture) as well as for the natural ecosystems so that both compete for water. The on-going increase of water consumption by agriculture and other human activities in this region has been enhancing the competition for water between human needs and nature. Against this background, 11 German and 6 Chinese universities and research institutes formed the consortium SuMaRiO (www.sumario.de), which aims at gaining a holistic picture of the availability of water resources in the Tarim River Basin and the impacts on anthropogenic activities and natural ecosystems caused by the water distribution within the Tarim River Basin. The discharge of the Aksu River, which is the major tributary to the Tarim, has been increasing over the past 6 decades due to enhanced glacier melt. Alone from 1989 to 2011, the area under agriculture more than doubled. Thereby, cotton became the major crop and there was a shift from small-scale farming to large-scale intensive farming. The major natural ecosystems along the Aksu and Tarim River are riparian ecosystems: Riparian (Tugai) forests, shrub vegetation, reed beds, and other grassland. Within the SuMaRiO Cluster the focus was laid on the Tugai forests, with Populus euphratica as dominant tree, because the most productive and species-rich natural ecosystems can be found among those forests. On sites with groundwater distance of less than 7.5 m the annual increments correlated with river runoffs of the previous year. But, the further downstream along the Tarim River, the more the natural river dynamics ceased, which impacts on the recruitment of Populus euphratica. Household surveys revealed that there is a considerable willingness to pay for conservation of those riparian forests with the mitigation of dust and sandstorms considered as the most important ecosystem service. This interdisciplinary project will result in a decision support tool (DST), build on the participation of regional stakeholders and models based on results and field experiments. This DST finally shall assist stakeholders in balancing the water competition acknowledging the major external effects of any water allocation.
Background: Lithium has proven suicide preventing effects in the long-term treatment of patients with affective disorders. Clinical evidence from case reports indicate that this effect may occur early on at the beginning of lithium treatment. The impact of lithium treatment on acute suicidal thoughts and/or behavior has not been systematically studied in a controlled trial. The primary objective of this confirmatory study is to determine the association between lithium therapy and acute suicidal ideation and/or suicidal behavior in inpatients with a major depressive episode (MDE, unipolar and bipolar disorder according to DSM IV criteria). The specific aim is to test the hypothesis that lithium plus treatment as usual (TAU), compared to placebo plus TAU, results in a significantly greater decrease in suicidal ideation and/or behavior over 5 weeks in inpatients with MDE.
Methods/Design: We initiated a randomized, placebo-controlled multicenter trial. Patients with the diagnosis of a moderate to severe depressive episode and suicidal thoughts and/or suicidal behavior measured with the Sheehan-Suicidality-Tracking Scale (S-STS) will be randomly allocated to add lithium or placebo to their treatment as usual. Change in the clinician administered S-STS from the initial to the final visit will be the primary outcome.
Discussion: There is an urgent need to identify treatments that will acutely decrease suicidal ideation and/or suicidal behavior. The results of this study will demonstrate whether lithium reduces suicidal ideation and behavior within the first 5 weeks of treatment.
The lncRNA GATA6-AS epigenetically regulates endothelial gene expression via interaction with LOXL2
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Impaired or excessive growth of endothelial cells contributes to several diseases. However, the functional involvement of regulatory long non-coding RNAs in these processes is not well defined. Here, we show that the long non-coding antisense transcript of GATA6 (GATA6-AS) interacts with the epigenetic regulator LOXL2 to regulate endothelial gene expression via changes in histone methylation. Using RNA deep sequencing, we find that GATA6-AS is upregulated in endothelial cells during hypoxia. Silencing of GATA6-AS diminishes TGF-β2-induced endothelial–mesenchymal transition in vitro and promotes formation of blood vessels in mice. We identify LOXL2, known to remove activating H3K4me3 chromatin marks, as a GATA6-AS-associated protein, and reveal a set of angiogenesis-related genes that are inversely regulated by LOXL2 and GATA6-AS silencing. As GATA6-AS silencing reduces H3K4me3 methylation of two of these genes, periostin and cyclooxygenase-2, we conclude that GATA6-AS acts as negative regulator of nuclear LOXL2 function.
Plants, fungi and algae are important components of global biodiversity and are fundamental to all ecosystems. They are the basis for human well-being, providing food, materials and medicines. Specimens of all three groups of organisms are accommodated in herbaria, where they are commonly referred to as botanical specimens.The large number of specimens in herbaria provides an ample, permanent and continuously improving knowledge base on these organisms and an indispensable source for the analysis of the distribution of species in space and time critical for current and future research relating to global biodiversity. In order to make full use of this resource, a research infrastructure has to be built that grants comprehensive and free access to the information in herbaria and botanical collections in general. This can be achieved through digitization of the botanical objects and associated data.The botanical research community can count on a long-standing tradition of collaboration among institutions and individuals. It agreed on data standards and standard services even before the advent of computerization and information networking, an example being the Index Herbariorum as a global registry of herbaria helping towards the unique identification of specimens cited in the literature.In the spirit of this collaborative history, 51 representatives from 30 institutions advocate to start the digitization of botanical collections with the overall wall-to-wall digitization of the flat objects stored in German herbaria. Germany has 70 herbaria holding almost 23 million specimens according to a national survey carried out in 2019. 87% of these specimens are not yet digitized. Experiences from other countries like France, the Netherlands, Finland, the US and Australia show that herbaria can be comprehensively and cost-efficiently digitized in a relatively short time due to established workflows and protocols for the high-throughput digitization of flat objects.Most of the herbaria are part of a university (34), fewer belong to municipal museums (10) or state museums (8), six herbaria belong to institutions also supported by federal funds such as Leibniz institutes, and four belong to non-governmental organizations. A common data infrastructure must therefore integrate different kinds of institutions.Making full use of the data gained by digitization requires the set-up of a digital infrastructure for storage, archiving, content indexing and networking as well as standardized access for the scientific use of digital objects. A standards-based portfolio of technical components has already been developed and successfully tested by the Biodiversity Informatics Community over the last two decades, comprising among others access protocols, collection databases, portals, tools for semantic enrichment and annotation, international networking, storage and archiving in accordance with international standards. This was achieved through the funding by national and international programs and initiatives, which also paved the road for the German contribution to the Global Biodiversity Information Facility (GBIF).Herbaria constitute a large part of the German botanical collections that also comprise living collections in botanical gardens and seed banks, DNA- and tissue samples, specimens preserved in fluids or on microscope slides and more. Once the herbaria are digitized, these resources can be integrated, adding to the value of the overall research infrastructure. The community has agreed on tasks that are shared between the herbaria, as the German GBIF model already successfully demonstrates.We have compiled nine scientific use cases of immediate societal relevance for an integrated infrastructure of botanical collections. They address accelerated biodiversity discovery and research, biomonitoring and conservation planning, biodiversity modelling, the generation of trait information, automated image recognition by artificial intelligence, automated pathogen detection, contextualization by interlinking objects, enabling provenance research, as well as education, outreach and citizen science.We propose to start this initiative now in order to valorize German botanical collections as a vital part of a worldwide biodiversity data pool.
Objectives: Current knowledge on infections caused by Scedosporium spp. and Lomentospora prolificans in children is scarce. We therefore aim to provide an overview of risk groups, clinical manifestation and treatment strategies of these infections.
Methods: Pediatric patients (age ≤18 years) with proven/probable Scedosporium spp. or L. prolificans infection were identified in PubMed and the FungiScope® registry. Data on diagnosis, treatment and outcome were collected.
Results: Fifty-five children (median age 9 years [IQR: 5–14]) with invasive Scedosporium spp. (n = 33) or L. prolificans (n = 22) infection were identified between 1990 and 2019. Malignancy, trauma and near drowning were the most common risk factors. Infections were frequently disseminated. Most patients received systemic antifungal therapy, mainly voriconazole and amphotericin B, plus surgical treatment.
Overall, day 42 mortality was 31%, higher for L. prolificans (50%) compared to Scedosporium spp. (18%). L. prolificans infection was associated with a shorter median survival time compared to Scedosporium spp. (6 days [IQR: 3–28] versus 61 days [IQR: 16–148]). Treatment for malignancy and severe disseminated infection were associated with particularly poor outcome (HR 8.33 [95% CI 1.35–51.40] and HR 6.12 [95% CI 1.52–24.66], respectively). Voriconazole use at any time and surgery for antifungal treatment were associated with improved clinical outcome (HR 0.33 [95% CI 0.11–0.99] and HR 0.09 [95% CI 0.02–0.40], respectively).
Conclusions: Scedosporium spp. and L. prolificans infections in children are associated with high mortality despite comprehensive antifungal therapy. Voriconazole usage and surgical intervention are associated with successful outcome.
Hintergrund: Viele Patienten mit Bagatellverletzungen gehen heutzutage häufig vorschnell in die Notaufnahmen und binden dort Ressourcen und Personal.
Ziel der Arbeit: Das Erstellen des Kosten-Erlös-Verhältnis der ambulanten Versorgung von Bagatellverletzungen in der unfallchirurgischen Notaufnahme.
Material und Methoden: Die Kalkulation erfolgte anhand der einheitlich abgerechneten Notfallpauschalen des Einheitlichen Bemessungsmaßstabes (EBM). Mittels der gängigen Tarifverträge für Ärzte und Pflegepersonal wurden Minutenkosten berechnet. Der zeitliche Behandlungsaufwand wurde anhand von 100 Referenzpatienten mit einer Bagatellverletzung ermittelt. Die Fallkostenkalkulation mit den jeweilig anfallenden Ressourcen erfolgte mit dem operativen Controlling des Universitätsklinikums Frankfurt.
Ergebnisse: Eingeschlossen wurden 4088 Patienten mit Bagatellverletzungen, welche sich 2019 eigenständig fußläufig vorstellten. Die häufigsten Gründe für die Vorstellung waren Prellungen der unteren (31,9 %; n = 1303) und oberen Extremität (16,6 %; n = 677). Kalkuliert wurden Zeitaufwände von 166,7 min/Tag für das ärztliche und 213,8 min/Tag für das Pflegepersonal. Es wurde ein Gesamterlös von 29.384,31 € und Gesamtlosten von 69.591,22 € berechnet. Somit lässt sich ein Erlösdefizit von 40.206,91 € für das Jahr 2019 berechnen. Das entspricht einem monetären Defizit von 9,84 €/Patienten.
Diskussion: Es herrscht Knappheit an der medizinischen Ressource „Personal“, um das heutzutage hohe Aufkommen an sich selbst vorstellenden fußläufigen Patienten mit Bagatellverletzungen zufriedenstellend und ökonomisch zu bewältigen. Die bisherige Vergütung der Behandlung von Bagatellverletzungen durch den EBM ist für den Krankenhaussektor unzureichend.
Folding of G-protein coupled receptors (GPCRs) according to the two-stage model (Popot, J. L., and Engelman, D. M. (1990) Biochemistry 29, 4031–4037) is postulated to proceed in 2 steps: partitioning of the polypeptide into the membrane followed by diffusion until native contacts are formed. Herein we investigate conformational preferences of fragments of the yeast Ste2p receptor using NMR. Constructs comprising the first, the first two, and the first three transmembrane (TM) segments, as well as a construct comprising TM1–TM2 covalently linked to TM7 were examined. We observed that the isolated TM1 does not form a stable helix nor does it integrate well into the micelle. TM1 is significantly stabilized upon interaction with TM2, forming a helical hairpin reported previously (Neumoin, A., Cohen, L. S., Arshava, B., Tantry, S., Becker, J. M., Zerbe, O., and Naider, F. (2009) Biophys. J. 96, 3187–3196), and in this case the protein integrates into the hydrophobic interior of the micelle. TM123 displays a strong tendency to oligomerize, but hydrogen exchange data reveal that the center of TM3 is solvent exposed. In all GPCRs so-far structurally characterized TM7 forms many contacts with TM1 and TM2. In our study TM127 integrates well into the hydrophobic environment, but TM7 does not stably pack against the remaining helices. Topology mapping in microsomal membranes also indicates that TM1 does not integrate in a membrane-spanning fashion, but that TM12, TM123, and TM127 adopt predominantly native-like topologies. The data from our study would be consistent with the retention of individual helices of incompletely synthesized GPCRs in the vicinity of the translocon until the complete receptor is released into the membrane interior.
Collective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle multiplicities comparable to peripheral Pb-Pb collisions. One of the possible signatures of collective behavior is the decrease of femtoscopic radii extracted from pion and kaon pairs emitted from high-multiplicity collisions with increasing pair transverse momentum. This decrease can be described in terms of an approximate transverse mass scaling. In the present work, femtoscopic analyses are carried out by the ALICE collaboration on charged pion and kaon pairs produced in pp collisions at s√=13 TeV from the LHC to study possible collectivity in pp collisions. The event-shape analysis method based on transverse sphericity is used to select for spherical versus jet-like events, and the effects of this selection on the femtoscopic radii for both charged pion and kaon pairs are studied. This is the first time this selection method has been applied to charged kaon pairs. An approximate transverse-mass scaling of the radii is found in all multiplicity ranges studied when the difference in the Lorentz boost for pions and kaons is taken into account. This observation does not support the hypothesis of collective expansion of hot and dense matter that should only occur in high-multiplicity events. A possible alternate explanation of the present results is based on a scenario of common emission conditions for pions and kaons in pp collisions for the multiplicity ranges studied.
The production yields of the Σ(1385)± and Ξ(1530)0 resonances are measured in pp collisions at s√=13 TeV with ALICE. The measurements are performed as a function of the charged particle multiplicity ⟨dNch/dη⟩, which is related to the energy density produced in the collision. The results include transverse momentum (pT) distributions, pT-integrated yields, mean transverse momenta of Σ(1385)± and Ξ(1530)0, as well as ratios of the pT-integrated resonance yields relative to yields of other hadron species. The Σ(1385)±/π± and Ξ(1530)0/π± yield ratios are consistent with the trend of the enhancement of strangeness production from low to high multiplicity pp collisions, which was previously observed for strange and multi-strange baryons. The yield ratio between the measured resonances and the long-lived baryons with the same strangeness content exhibits a hint of a mild increasing trend at low multiplicity, despite too large uncertainties to exclude the flat behaviour. The results are compared to predictions from models such as EPOS-LHC and PYTHIA 8 with Rope shoving. The latter provides the best description of the multiplicity dependence of the Σ(1385)± and Ξ(1530)0 production in pp collisions at s√=13 TeV.
Measurements of the production cross sections of prompt D0, D+, D∗+, D+s, Λ+c, and Ξ+c charm hadrons at midrapidity in proton−proton collisions at s√=13 TeV with the ALICE detector are presented. The D-meson cross sections as a function of transverse momentum (pT) are provided with improved precision and granularity. The ratios of pT-differential meson production cross sections based on this publication and on measurements at different rapidity and collision energy provide a constraint on gluon parton distribution functions at low values of Bjorken-x (10−5−10−4). The measurements of Λ+c (Ξ+c) baryon production extend the measured pT intervals down to pT=0(3)~GeV/c. These measurements are used to determine the charm-quark fragmentation fractions and the cc¯¯ production cross section at midrapidity (|y|<0.5) based on the sum of the cross sections of the weakly-decaying ground-state charm hadrons D0, D+, D+s, Λ+c, Ξ0c and, for the first time, Ξ+c, and of the strongly-decaying J/psi mesons. The first measurements of Ξ+c and Σ0,++c fragmentation fractions at midrapidity are also reported. A significantly larger fraction of charm quarks hadronising to baryons is found compared to e+e− and ep collisions. The cc¯¯ production cross section at midrapidity is found to be at the upper bound of state-of-the-art perturbative QCD calculations.
Measurements of the production cross sections of prompt D0, D+, D∗+, D+s, Λ+c, and Ξ+c charm hadrons at midrapidity in proton−proton collisions at s√=13 TeV with the ALICE detector are presented. The D-meson cross sections as a function of transverse momentum (pT) are provided with improved precision and granularity. The ratios of pT-differential meson production cross sections based on this publication and on measurements at different rapidity and collision energy provide a constraint on gluon parton distribution functions at low values of Bjorken-x (10−5−10−4). The measurements of Λ+c (Ξ+c) baryon production extend the measured pT intervals down to pT=0(3)~GeV/c. These measurements are used to determine the charm-quark fragmentation fractions and the cc¯¯ production cross section at midrapidity (|y|<0.5) based on the sum of the cross sections of the weakly-decaying ground-state charm hadrons D0, D+, D+s, Λ+c, Ξ0c and, for the first time, Ξ+c, and of the strongly-decaying J/psi mesons. The first measurements of Ξ+c and Σ0,++c fragmentation fractions at midrapidity are also reported. A significantly larger fraction of charm quarks hadronising to baryons is found compared to e+e− and ep collisions. The cc¯¯ production cross section at midrapidity is found to be at the upper bound of state-of-the-art perturbative QCD calculations.
This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s√ = 13 TeV. Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4<|Δη|<1.8 and a transverse momentum of 1<pT<2 GeV/c, as a function of the charged-particle multiplicity measured at midrapidity. This study extends the measurements of the ridge yield to the low multiplicity region, where in hadronic collisions it is typically conjectured that a strongly-interacting medium is unlikely to be formed. The precision of the new results allows for the first direct quantitative comparison with the results obtained in e+e− collisions at s√ = 91 GeV, where initial-state effects such as pre-equilibrium dynamics and collision geometry are not expected to play a role. In the multiplicity range where the e+e− results have good precision, the measured ridge yields in pp collisions are substantially larger than the limits set in e+e− annihilations. Consequently, the findings presented in this Letter suggest that the processes involved in e+e− annihilations do not contribute significantly to the emergence of long-range correlations in pp collisions.
The two-particle momentum correlation functions between charm mesons (D∗± and D±) and charged light-flavor mesons (π± and K±) in all charge-combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton-proton collisions at a center-of-mass energy of s√=13 TeV. For DK and D∗K pairs, the experimental results are in agreement with theoretical predictions of the residual strong interaction based on quantum chromodynamics calculations on the lattice and chiral effective field theory. In the case of Dπ and D∗π pairs, tension between the calculations including strong interactions and the measurement is observed. For all particle pairs, the data can be adequately described by Coulomb interaction only, indicating a shallow interaction between charm and light-flavor mesons. Finally, the scattering lengths governing the residual strong interaction of the Dπ and D∗π systems are determined by fitting the experimental correlation functions with a model that employs a Gaussian potential. The extracted values are small and compatible with zero.
This Letter presents the first measurement of event-by-event fluctuations of the net number (difference between the particle and antiparticle multiplicities) of multistrange hadrons Ξ− and Ξ¯¯¯¯+ and its correlation with the net-kaon number using the data collected by the ALICE Collaboration in pp, p−Pb, and Pb−Pb collisions at a center-of-mass energy per nucleon pair sNN−−−√=5.02 TeV. The statistical hadronization model with a correlation over three units of rapidity between hadrons having the same and opposite strangeness content successfully describes the results. On the other hand, string-fragmentation models that mainly correlate strange hadrons with opposite strange quark content over a small rapidity range fail to describe the data.
he first measurement of 3ΛH and 3Λ¯¯¯¯H¯¯¯¯ differential production with respect to transverse momentum and centrality in Pb−Pb collisions at sNN−−−√=5.02~TeV is presented. The 3ΛH has been reconstructed via its two-charged-body decay channel, i.e., 3ΛH→3He+π−. A Blast-Wave model fit of the pT-differential spectra of all nuclear species measured by the ALICE collaboration suggests that the 3ΛH kinetic freeze-out surface is consistent with that of other nuclei. The ratio between the integrated yields of 3ΛH and 3He is compared to predictions from the statistical hadronisation model and the coalescence model, with the latter being favoured by the presented measurements.
First measurements of hadron(h)−Λ azimuthal angular correlations in p−Pb collisions at sNN−−−√ = 5.02 TeV using the ALICE detector at the LHC are presented. These correlations are used to separate the production of associated Λ baryons into three different kinematic regions, namely those produced in the direction of the trigger particle (near-side), those produced in the opposite direction (away-side), and those whose production is uncorrelated with the jet-axis (underlying event). The per-trigger associated Λ yields in these regions are extracted, along with the near- and away-side azimuthal peak widths, and the results are studied as a function of associated particle pT and event multiplicity. Comparisons with the DPMJET event generator and previous measurements of the ϕ(1020) meson are also made. The final results indicate that strangeness production in the highest multiplicity p−Pb collisions is enhanced relative to low multiplicity collisions in the jet-like regions, as well as the underlying event. The production of Λ relative to charged hadrons is also enhanced in the underlying event when compared to the jet-like regions. Additionally, the results hint that strange quark production in the away-side of the jet is modified by soft interactions with the underlying event.