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We report precision measurements of hypernuclei 3ΛH and 4ΛH lifetimes obtained from Au+Au collisions at \snn = 3.0\,GeV and 7.2\,GeV collected by the STAR experiment at RHIC, and the first measurement of 3ΛH and 4ΛH mid-rapidity yields in Au+Au collisions at \snn = 3.0\,GeV. 3ΛH and 4ΛH, being the two simplest bound states composed of hyperons and nucleons, are cornerstones in the field of hypernuclear physics. Their lifetimes are measured to be 221±15(stat.)±19(syst.)\,ps for 3ΛH and 218±6(stat.)±13(syst.)\,ps for 4ΛH. The pT-integrated yields of 3ΛH and 4ΛH are presented in different centrality and rapidity intervals. It is observed that the shape of the rapidity distribution of 4ΛH is different for 0--10\% and 10--50\% centrality collisions. Thermal model calculations, using the canonical ensemble for strangeness, describes the 3ΛH yield well, while underestimating the 4ΛH yield. Transport models, combining baryonic mean-field and coalescence (JAM) or utilizing dynamical cluster formation via baryonic interactions (PHQMD) for light nuclei and hypernuclei production, approximately describe the measured 3ΛH and 4ΛH yields. Our measurements provide means to precisely assess our understanding of the fundamental baryonic interactions with strange quarks, which can impact our understanding of more complicated systems involving hyperons, such as the interior of neutron stars or exotic hypernuclei.
We report precision measurements of hypernuclei 3ΛH and 4ΛH lifetimes obtained from Au+Au collisions at \snn = 3.0\,GeV and 7.2\,GeV collected by the STAR experiment at RHIC, and the first measurement of 3ΛH and 4ΛH mid-rapidity yields in Au+Au collisions at \snn = 3.0\,GeV. 3ΛH and 4ΛH, being the two simplest bound states composed of hyperons and nucleons, are cornerstones in the field of hypernuclear physics. Their lifetimes are measured to be 221±15(stat.)±19(syst.)\,ps for 3ΛH and 218±6(stat.)±13(syst.)\,ps for 4ΛH. The pT-integrated yields of 3ΛH and 4ΛH are presented in different centrality and rapidity intervals. It is observed that the shape of the rapidity distribution of 4ΛH is different for 0--10\% and 10--50\% centrality collisions. Thermal model calculations, using the canonical ensemble for strangeness, describes the 3ΛH yield well, while underestimating the 4ΛH yield. Transport models, combining baryonic mean-field and coalescence (JAM) or utilizing dynamical cluster formation via baryonic interactions (PHQMD) for light nuclei and hypernuclei production, approximately describe the measured 3ΛH and 4ΛH yields. Our measurements provide means to precisely assess our understanding of the fundamental baryonic interactions with strange quarks, which can impact our understanding of more complicated systems involving hyperons, such as the interior of neutron stars or exotic hypernuclei.
We report a new measurement of the production cross section for inclusive electrons from open heavy-flavor hadron decays as a function of transverse momentum (pT) at mid-rapidity (|y|< 0.7) in p+p collisions at s√=200 GeV. The result is presented for 2.5 <pT< 10 GeV/c with an improved precision at high pT with respect to the previous measurements, and thus provides a better constraint on perturbative QCD calculations. Moreover, this measurement also provides a high-precision reference for measurements of nuclear modification factors for inclusive electrons from open-charm and -bottom hadron decays in heavy-ion collisions.
We report a new measurement of the production cross section for inclusive electrons from open heavy-flavor hadron decays as a function of transverse momentum (pT) at mid-rapidity (|y|< 0.7) in p+p collisions at s√=200 GeV. The result is presented for 2.5 <pT< 10 GeV/c with an improved precision above 6 GeV/c with respect to the previous measurements, providing more constraints on perturbative QCD calculations. Moreover, this measurement also provides a high-precision reference for measurements of nuclear modification factors for inclusive electrons from open-charm and -bottom hadron decays in heavy-ion collisions.
The STAR collaboration presents jet substructure measurements related to both the momentum fraction and the opening angle within jets in p+p and Au+Au collisions at sNN−−−√=200 GeV. The substructure observables include SoftDrop groomed momentum fraction (zg), groomed jet radius (Rg), and subjet momentum fraction ((zSJ)) and opening angle ((θSJ)). The latter observable is introduced for the first time. Fully corrected subjet measurements are presented for p+p collisions and are compared to leading order Monte Carlo models. The subjet θSJ distributions reflect the jets leading opening angle and are utilized as a proxy for the resolution scale of the medium in Au+Au collisions. We compare data from Au+Au collisions to those from p+p which are embedded in minimum-bias Au+Au events in order to include the effects of detector smearing and the heavy-ion collision underlying event. The subjet observables are shown to be more robust to the background than zg and (Rg).
We observe no significant modifications of the subjet observables within the two highest-energy, back-to-back jets, resulting in a distribution of opening angles and the splittings that are vacuum-like. We also report measurements of the differential di-jet momentum imbalance (AJ) for jets of varying θg. We find no qualitative differences in energy loss signatures for varying angular scales in the range 0.1<θSJ<0.3, leading to the possible interpretation that energy loss in this population of high momentum di-jet pairs, is due to soft medium-induced gluon radiation from a single color-charge as it traverses the medium.
The STAR collaboration presents jet substructure measurements related to both the momentum fraction and the opening angle within jets in \pp and \AuAu collisions at \sqrtsn =200 GeV. The substructure observables include SoftDrop groomed momentum fraction (\zg), groomed jet radius (\rg), and subjet momentum fraction (\zsj) and opening angle (\tsj). The latter observable is introduced for the first time. Fully corrected subjet measurements are presented for \pp collisions and are compared to leading order Monte Carlo models. The subjet \tsj~distributions reflect the jets leading opening angle and are utilized as a proxy for the resolution scale of the medium in \AuAu collisions. We compare data from \AuAu collisions to those from \pp which are embedded in minimum-bias \AuAu events in order to include the effects of detector smearing and the heavy-ion collision underlying event. The subjet observables are shown to be more robust to the background than \zg~and \rg.
We observe no significant modifications of the subjet observables within the two highest-energy, back-to-back jets, resulting in a distribution of opening angles and the splittings that are vacuum-like. We also report measurements of the differential di-jet momentum imbalance (AJ) for jets of varying \tsj. We find no qualitative differences in energy loss signatures for varying angular scales in the range 0.1< \tsj <0.3, leading to the possible interpretation that energy loss in this population of high momentum di-jet pairs, is due to soft medium-induced gluon radiation from a single color-charge as it traverses the medium.
We report on the first measurements of J/ψ production at very low transverse momentum (pT< 0.2 GeV/c) in hadronic Au+Au collisions at √sNN = 200 GeV and U+U collisions at √sNN = 193 GeV. Remarkably, the inferred nuclear modification factor of J/ψ at mid-rapidity in Au+Au (U+U) collisions reaches about 24 (52) for pT< 0.05 GeV/c in the 60-80% collision centrality class. This noteworthy enhancement cannot be explained by hadronic production accompanied by cold and hot medium effects. In addition, the dN/dt distribution of J/ψ for the very low pT range is presented for the first time. The distribution is consistent with that expected from the Au nucleus and shows a hint of interference. Comparison of the measurements to theoretical calculations of coherent production shows that the excess yield can be described reasonably well and reveals a partial disruption of coherent production in semi-central collisions, perhaps due to the violent hadronic interactions. Incorporating theoretical calculations, the results strongly suggest that the dramatic enhancement of J/ψ yield observed at extremely low pT originates from coherent photon-nucleus interactions. In particular, coherently produced J/ψ's in violent hadronic collisions may provide a novel probe of the quark-gluon-plasma.
We report on the first measurements of J/ψ production at very low transverse momentum (pT< 0.2 GeV/c) in hadronic Au+Au collisions at √sNN = 200 GeV and U+U collisions at √sNN = 193 GeV. Remarkably, the inferred nuclear modification factor of J/ψ at mid-rapidity in Au+Au (U+U) collisions reaches about 24 (52) for pT< 0.05 GeV/c in the 60-80% collision centrality class. This noteworthy enhancement cannot be explained by hadronic production accompanied by cold and hot medium effects. In addition, the dN/dt distribution of J/ψ for the very low pT range is presented for the first time. The distribution is consistent with that expected from the Au nucleus and shows a hint of interference. Comparison of the measurements to theoretical calculations of coherent production shows that the excess yield can be described reasonably well and reveals a partial disruption of coherent production in semi-central collisions, perhaps due to the violent hadronic interactions. Incorporating theoretical calculations, the results strongly suggest that the dramatic enhancement of J/ψ yield observed at extremely low pT originates from coherent photon-nucleus interactions. In particular, coherently produced J/ψ's in violent hadronic collisions may provide a novel probe of the quark-gluon-plasma.
We report new STAR measurements of the single-spin asymmetries 𝐴𝐿 for 𝑊+ and 𝑊− bosons produced in polarized proton-proton collisions at √𝑠=510 GeV as a function of the decay-positron and decay-electron pseudorapidity. The data were obtained in 2013 and correspond to an integrated luminosity of 250 pb−1. The results are combined with previous results obtained with 86 pb−1. A comparison with theoretical expectations based on polarized lepton-nucleon deep-inelastic scattering and prior polarized proton-proton data suggests a difference between the ¯𝑢 and ¯𝑑 quark helicity distributions for 0.05<𝑥<0.25. In addition, we report new results for the double-spin asymmetries 𝐴𝐿𝐿 for 𝑊±, as well as 𝐴𝐿 for 𝑍/𝛾* production and subsequent decay into electron-positron pairs.
Transverse spin transfer to Λ and ¯Λ hyperons in polarized proton-proton collisions at √𝑠=200 GeV
(2018)
The transverse spin transfer from polarized protons to Λ and Λ¯ hyperons is expected to provide sensitivity to the transversity distribution of the nucleon and to the transversely polarized fragmentation functions. We report the first measurement of the transverse spin transfer to Λ and Λ¯ along the polarization direction of the fragmenting quark, DTT, in transversely polarized proton-proton collisions at s√=200GeV with the STAR detector at RHIC. The data correspond to an integrated luminosity of 18pb−1 and cover the pseudorapidity range |η|<1.2 and transverse momenta pT up to 8GeV/c. The dependence on pT and η are presented. The DTT results are found to be comparable with a model prediction, and are also consistent with zero within uncertainties.
The electron-capture process was studied for Xe54+ colliding with H2 molecules at the internal gas target of the Experimental Storage Ring (ESR) at GSI, Darmstadt. Cross-section values for electron capture into excited projectile states were deduced from the observed emission cross section of Lyman radiation, being emitted by the hydrogenlike ions subsequent to the capture of a target electron. The ion beam energy range was varied between 5.5 and 30.9 MeV/u by applying the deceleration mode of the ESR. Thus, electron-capture data were recorded at the intermediate and, in particular, the low-collision-energy regime, well below the beam energy necessary to produce bare xenon ions. The obtained data are found to be in reasonable qualitative agreement with theoretical approaches, while a commonly applied empirical formula significantly overestimates the experimental findings.
Outcomes of SARS-CoV-2 infections in patients with neurodegenerative diseases in the LEOSS cohort
(2021)
The impact of preexisting neurodegenerative diseases on superimposed SARS-CoV-2 infections remains controversial. Here we examined the course and outcome of SARS-CoV-2 infections in patients affected by Parkinson's disease (PD) or dementia compared to matched controls without neurodegenerative diseases in the LEOSS (Lean European Open Survey on SARS-CoV-2-infected patients) cohort, a large-scale prospective multicenter cohort study...
Die Hippocampusformation ist eine wichtige Hirnstruktur für die Gedächtnisakquisition und -konsolidierung, insbesondere beim räumlichen Lernen spielt sie eine essentielle Rolle. Langzeitpotenzierung (LTP) gilt als das elektrophysiologische Korrelat der synaptischen Plastizität, dem langfristigen Umbau synaptischer Verbindungen, der letztlich zur Ausbildung stabiler, langanhaltender Erinnerungen führt. Signalübertragung über den cAMP/PKA/MAPK/CREB-Weg stellt den wichtigsten molekularen Mechanismus der Langzeitpotenzierung dar, CREB gilt als die zentrale Komponente und Schnittstelle dieser Übertragung. Neuronale Plastizität ist abhängig von de-novo-Pro-teinbiosynthese, an deren Regulation Veränderungen der Chromatinstruktur durch Histonmodifikationen beteiligt ist, in die der genannte Signalweg mündet.
Circadiane Rhythmen sind in den meisten Spezies in vielen verschiedenen Organen und Geweben nachgewiesen und manifestieren sich als Einflüsse auf zahlreiche Parameter des Verhaltens, so auch auf die Leistung beim Erlernen neuer Information. Ihr zentraler Taktgeber ist der Nucleus suprachiasmaticus (SCN). Melatonin ist ein wichtiges Effektorsignal des circadianen Systems und hat gleichzeitig Rückkopplungsfunktion. Seine unmittelbare Wirkung übt es über die beiden G-Protein-gekoppelten Melatonin-rezeptoren MT1 und MT2 aus. Es hat direkten Einfluss auf das Lernen und stellt damit einen Schnittpunkt zwischen Signalwegen der synaptischen Plastizität und des circadianen Systems dar.
Der Lernerfolg vieler Tierarten ist bekanntermaßen während deren subjektivem Tag höher als während der Nacht. In dieser Arbeit konnte gezeigt werden, dass beim räumlichen Lernen bereits ein einmaliger Stimulus ausreicht, um im Hippocampus der verwendeten C3H-Mäuse eine stabile Induktion der Phosphorylierung von CREB sowie der transkriptionsaktivierenden Histonmodifikationen H3K9ac und H3K14ac zu erzeugen. Ein einmaliger Stimulus hat also verstärkte Signaltransduktion und Protein-syntheseaktivität als Zeichen synaptischer Plastizität zur Folge. Dies geschieht nur tagsüber, nachts zeigt sich kein Effekt. Somit spiegelt sich der Phänotyp in diesen molekularen Markern wider. Anhand eines Mausmodells mit genetischem Knockout der beiden membrangebundenen Melatoninrezeptoren MT1 und MT2 (MT1/2−/−) wurde der Einfluss von Melatonin auf die molekularen Prozesse des hippocampalen Lernens näher beleuchtet. Über MT1/2−/−-Mäuse ist bekannt, dass ihr Lernerfolg in den benutzten Verhaltensversuchen zu jeder Tageszeit auf dem Niveau der C3H-Mäuse während der Nacht liegt. Zunächst zeigt sich, dass in MT1/2−/−-Mäusen die Grundrhythmen der meisten untersuchten Proteine und Histonmodifikationen verändert, teilweise phasenverschoben und abgeflacht sind. Eine Induktion von pCREB und H3K9ac und H3K14ac ist in diesen Tieren nicht mehr erreichbar und somit nach einem einmaligen Lernstimulus keine vermehrte Signalübertragung oder synaptischer Umbau nachweisbar. Auch hier besteht eine gute Korrelation mit dem Lernphänotyp. Weiterhin wurden Unterschiede im Aktivitätsmuster der beiden Mäusestämme gezeigt, MT1/2−/−-Mäuse sind abhängig von der Situation weniger oder gleich aktiv wie C3H-Tiere. Im Angstverhalten als möglichem Störfaktor besteht kein Unterschied zwischen beiden Tierstämmen.
Melatoninrezeptoren wirken über inhibitorische G-Proteine auf die Adenylatcyclase und hemmen den cAMP/CREB-Signalübertragung, was die schlechtere Lernperformance während der Nacht erklärt, wenn der Melatoninspiegel seinen natürlichen Höhepunkt erreicht. Durch Melatonin lassen sich auch tagsüber bei Mäusen und Zebrafischen LTP und räumliches Lernen unterdrücken. Jedoch lässt sich durch diese akute Wirkung von Melatonin nur ein Teil der Ergebnisse erklären, so zum Beispiel die veränderte Aktivität von PKA und PKC. Um das scheinbar paradoxe verschlechterte Lernverhalten der MT1/2−/−-Mäuse und die fehlende Induzierbarkeit von pCREB und Chromatinremodelling zu erklären, muss ein längerfristiger Effekt von Melatonin bestehen, der über dessen maximale Konzentration hinaus anhält und in seiner Abwesenheit zu verbesserter Signalübertragung führt. Hierfür ist eine Sensibilisierung der Adenylatcyclase durch prolongierte Melatoninexposition, wie sie beispielsweise in Zellen der Pars tuberalis nachgewiesen wurde, beschrieben worden. Es konnte in dieser Arbeit gezeigt werden, dass Melatonin vielfältigen Einfluss auf das hippocampale Lernen hat und dieses mit der inneren Uhr verbindet.
Background: Biological psychiatry aims to understand mental disorders in terms of altered neurobiological pathways. However, for one of the most prevalent and disabling mental disorders, Major Depressive Disorder (MDD), patients only marginally differ from healthy individuals on the group-level. Whether Precision Psychiatry can solve this discrepancy and provide specific, reliable biomarkers remains unclear as current Machine Learning (ML) studies suffer from shortcomings pertaining to methods and data, which lead to substantial over-as well as underestimation of true model accuracy.
Methods: Addressing these issues, we quantify classification accuracy on a single-subject level in N=1,801 patients with MDD and healthy controls employing an extensive multivariate approach across a comprehensive range of neuroimaging modalities in a well-curated cohort, including structural and functional Magnetic Resonance Imaging, Diffusion Tensor Imaging as well as a polygenic risk score for depression.
Findings Training and testing a total of 2.4 million ML models, we find accuracies for diagnostic classification between 48.1% and 62.0%. Multimodal data integration of all neuroimaging modalities does not improve model performance. Similarly, training ML models on individuals stratified based on age, sex, or remission status does not lead to better classification. Even under simulated conditions of perfect reliability, performance does not substantially improve. Importantly, model error analysis identifies symptom severity as one potential target for MDD subgroup identification.
Interpretation: Although multivariate neuroimaging markers increase predictive power compared to univariate analyses, single-subject classification – even under conditions of extensive, best-practice Machine Learning optimization in a large, harmonized sample of patients diagnosed using state-of-the-art clinical assessments – does not reach clinically relevant performance. Based on this evidence, we sketch a course of action for Precision Psychiatry and future MDD biomarker research.