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Inclusive transverse momentum spectra of primary charged particles in Pb–Pb collisions at √sNN=2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0–5% and 70–80% of the hadronic Pb–Pb cross section. The measured charged particle spectra in |η|<0.8 and 0.3<pT<20 GeV/c are compared to the expectation in pp collisions at the same sNN, scaled by the number of underlying nucleon–nucleon collisions. The comparison is expressed in terms of the nuclear modification factor RAA. The result indicates only weak medium effects (RAA≈0.7) in peripheral collisions. In central collisions, RAA reaches a minimum of about 0.14 at pT=6–7 GeV/c and increases significantly at larger pT. The measured suppression of high-pT particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb–Pb collisions at the LHC.
The inclusive charged particle transverse momentum distribution is measured in proton–proton collisions at s=900 GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region (|η|<0.8) over the transverse momentum range 0.15<pT<10 GeV/c. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for |η|<0.8 is 〈pT〉INEL=0.483±0.001 (stat.)±0.007 (syst.) GeV/c and 〈pT〉NSD=0.489±0.001 (stat.)±0.007 (syst.) GeV/c, respectively. The data exhibit a slightly larger 〈pT〉 than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET.
Rapidity and transverse momentum dependence of inclusive J/ψ production in pp collisions at √s=7 TeV
(2011)
The ALICE experiment at the LHC has studied inclusive J/ψ production at central and forward rapidities in pp collisions at √s=7 TeV. In this Letter, we report on the first results obtained detecting the J/ψ through the dilepton decay into e+e− and μ+μ− pairs in the rapidity ranges |y|<0.9 and 2.5<y<4, respectively, and with acceptance down to zero pT. In the dielectron channel the analysis was carried out on a data sample corresponding to an integrated luminosity Lint=5.6 nb−1 and the number of signal events is NJ/ψ=352±32(stat.)±28(syst.); the corresponding figures in the dimuon channel are Lint=15.6 nb−1 and NJ/ψ=1924±77(stat.)±144(syst.). The measured production cross sections are σJ/ψ(|y|<0.9)=10.7±1.0(stat.)±1.6(syst.)−2.3+1.6(syst.pol.)μb and σJ/ψ(2.5<y<4)=6.31±0.25(stat.)±0.76(syst.)−1.96+0.95(syst.pol.)μb. The differential cross sections, in transverse momentum and rapidity, of the J/ψ were also measured.
Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p–Pb collisions at a nucleon–nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 < pT,assoc < pT,trig < 5.0 GeV/c is examined, to include correlations induced by jets originating from low momentum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range |η| < 0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p–Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton–parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p–Pb collisions. Further, the number scales only in the intermediate multiplicity region with the number of binary nucleon–nucleon collisions estimated with a Glauber Monte-Carlo simulation.
Freeze-out radii extracted from three-pion cumulants in pp, p–Pb and Pb–Pb collisions at the LHC
(2014)
In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose–Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correlations in pp, p–Pb and Pb–Pb collisions at the LHC with ALICE. At similar multiplicity, the invariant radii extracted in p–Pb collisions are found to be 5–15% larger than those in pp, while those in Pb–Pb are 35–55% larger than those in p–Pb. Our measurements disfavor models which incorporate substantially stronger collective expansion in p–Pb as compared to pp collisions at similar multiplicity.
We report on the measurement of the inclusive Υ (1S) production in Pb–Pb collisions at √sNN = 2.76 TeV carried out at forward rapidity (2.5 < y < 4) and down to zero transverse momentum using its μ+μ−decay channel with the ALICE detector at the Large Hadron Collider. A strong suppression of the inclusive Υ (1S) yield is observed with respect to pp collisions scaled by the number of independent nucleon–nucleon collisions. The nuclear modification factor, for events in the 0–90% centrality range, amounts to 0.30 ± 0.05(stat) ± 0.04(syst). The observed Υ (1S) suppression tends to increase with the centrality of the collision and seems more pronounced than in corresponding mid-rapidity measurements. Our results are compared with model calculations, which are found to underestimate the measured suppression and fail to reproduce its rapidity dependence.
Einleitung: Für angehende Ärztinnen und Ärzte sind gründliche biochemische Kenntnisse von großer Bedeutung für das Verständnis molekularer Mechanismen, physiologischer Abläufe und pathologischer Entwicklungen. Entsprechend nimmt die biochemische Lehre im vorklinischen Abschnitt des Medizinstudiums viel Zeit in Anspruch. Zugleich ist aber die Biochemie bei den Studienanfängern ein ungeliebtes Fach: Die Stofffülle, die Komplexität molekularer Prozesse, das geforderte hohe Abstraktionsniveau und die oft unzureichenden schulischen Vorkenntnisse führen bei vielen Erstsemestern zu tiefer Abneigung gegenüber der molekularen Medizin. Um diesem Problem zu begegnen, bieten wir den Medizinstudierenden der Johann Wolfgang Goethe-Universität als vorklinisches Wahlfach eine neuartige Lehrveranstaltung an, die multimedial-biografische Vorträge mit biochemischem Unterricht kombiniert.
Methodik: Das Institut für Biochemie am FB Medizin führt eine propädeutische Lehrveranstaltung durch, in der Biografien bekannter Persönlichkeiten ebenso wie die korrespondierenden Krankheiten vorgestellt werden. Konzipiert als Wahlpflichtfach bietet diese multimediale Lehrveranstaltung (Titel: "Leben und Leiden berühmter Persönlichkeiten. Eine Einführung in die molekulare Medizin") den 40 teilnehmenden Studierenden in zehn wöchentlichen Doppelsitzungen pro Studienjahr einen breitgefächerten Lernstoff mit drei Lernzielen:
1. Im ersten Teil (45 Min.) jeder Doppelsitzung werden Leben, Leiden und Werk berühmter Persöhnlichkeiten aus Literatur, Musik, Politik, Kunst, Sport und Wissenschaft vorgestellt, die an einer bekannten Krankheit litten bzw. leiden. Unterstützt wird dieser biografische Vortrag in der Regel durch multimediale Einspielungen kurzer Video-Clips oder Musikstücke.
2. Im zweiten Teil (75 Min.) werden die molekularmedizinischen Hintergründe dieser Erkrankungen in einem biochemischen Vortrag vermittelt.
3. Dieser Vortrag wird durch Kurzreferate (jeweils 5 min.) der Studierenden zu grundlegenden biochemischen Strukturen und Prozessen ergänzt.
Unter den regelmäßig angebotenen Doppel-Themen sind: der Rockmusiker Freddy Mercury (AIDS), der Schriftsteller Ernest Hemingway (Alkoholismus), der Rock ´n Roll-Sänger Elvis Presley (Diabetes), der Komponist Ludwig van Beethoven (Morbus Crohn), der Boxer Muhammad Ali (Morbus Parkinson), der Rockmusiker Frank Zappa (Krebs).
Ergebnisse: Die Vortragsreihe wurde seit 2005 zum vierten Mal durchgeführt. Die Evaluation durch die Teilnehmer mittels Fragebogen ergab durchweg eine gute bis sehr gute Gesamtbewertung. Der Lernerfolg für die biochemischen Grundlagen wurde hoch eingeschätzt. Die multimedial präsentierten Biografien wurden als sinnvolle Ergänzung zu den molekularmedizinischen Themen empfunden.
Schlussfolgerung: Das studentische Feed-back bestätigt die Vermutung, dass diese spezifische Kombination die Attraktivität und Akzeptanz von Biochemie und Molekularbiologie bei den Studienanfängern erheblich steigert.
Bei den vorliegenden Zielvereinbarungen zwischen dem HMWK und den zwölf hessischen Hochschulen handelt es sich um Leistungsvereinbarungen, die auf dem Hochschulpakt für die Jahre 2011 bis 2015 (vom 18. Mai 2010) aufbauen. Wurden im Hochschulpakt vornehmlich strategische Regelungen hinsichtlich der Finanzierung der Hochschulen und der hochschulpolitischen Ziele getroffen, werden nunmehr mit den inzwischen zum dritten Male abgeschlossenen Zielvereinbarungen vor allem strategische Schwerpunkte in der Hochschulentwicklung gesetzt. ...
Although the concept that dendritic cells (DCs) recognize pathogens through the engagement of Toll-like receptors is widely accepted, we recently suggested that immature DCs might sense kinin-releasing strains of Trypanosoma cruzi through the triggering of G-protein-coupled bradykinin B2 receptors (B2R). Here we report that C57BL/6.B2R-/- mice infected intraperitoneally with T. cruzi display higher parasitemia and mortality rates as compared to B2R+/+ mice. qRT-PCR revealed a 5-fold increase in T. cruzi DNA (14 d post-infection [p.i.]) in B2R-/- heart, while spleen parasitism was negligible in both mice strains. Analysis of recall responses (14 d p.i.) showed high and comparable frequencies of IFN-gamma-producing CD4+ and CD8+ T cells in the spleen of B2R-/- and wild-type mice. However, production of IFN-gamma by effector T cells isolated from B2R-/- heart was significantly reduced as compared with wild-type mice. As the infection continued, wild-type mice presented IFN-gamma-producing (CD4+CD44+ and CD8+CD44+) T cells both in the spleen and heart while B2R-/- mice showed negligible frequencies of such activated T cells. Furthermore, the collapse of type-1 immune responses in B2R-/- mice was linked to upregulated secretion of IL-17 and TNF-alpha by antigen-responsive CD4+ T cells. In vitro analysis of tissue culture trypomastigote interaction with splenic CD11c+ DCs indicated that DC maturation (IL-12, CD40, and CD86) is controlled by the kinin/B2R pathway. Further, systemic injection of trypomastigotes induced IL-12 production by CD11c+ DCs isolated from B2R+/+ spleen, but not by DCs from B2R-/- mice. Notably, adoptive transfer of B2R+/+ CD11c+ DCs (intravenously) into B2R-/- mice rendered them resistant to acute challenge, rescued development of type-1 immunity, and repressed TH17 responses. Collectively, our results demonstrate that activation of B2R, a DC sensor of endogenous maturation signals, is critically required for development of acquired resistance to T. cruzi infection. Author Summary: Antibodies and IFN-gamma-producing effector T cells are essential for the immune control of infection by Trypanosoma cruzi, the intracellular protozoa that causes human Chagas disease. Despite the potency of anti-parasite immunity, the parasites are not cleared from their intracellular niches. Instead, a low grade chronic infection prevails, provoking severe immunopathology in the myocardium. Although it is well established that innate sentinel cells sense T. cruzi through receptors for microbial structures, such as Toll-like receptors, it remained unclear whether endogenous inflammatory signals also contribute to the development of adaptive immunity. The present study was motivated by awareness that T. cruzi trypomastigotes (extracellular infective forms) are equipped with proteases that liberate the pro-inflammatory bradykinin peptide from an internal segment of kininogens. Here we demonstrate that splenic dendritic cells (DCs), the antigen-presenting cells that coordinate the adaptive branch of immunity in lymphoid tissues, are potently activated via G-protein-coupled bradykinin B2 receptors (B2R). Analysis of the outcome of infection in B2R-knockout mice revealed that the mutant mice developed a typical susceptible phenotype, owing to impaired development of IFN-gamma-producing effector T cells. Notably, the immune dysfunction of B2R-knockout mice was corrected upon cell transfer of wild-type DCs, thus linking development of protective T cells to DCs' sensing of endogenous danger signals (kinins) released by trypomastigotes.
Die Goethe-Universität hat sich als eine der ersten deutschen Universitäten dem Urteil ihrer Studierenden gestellt: Die im Juni veröffentlichte repräsentative Umfrage ist eine der umfassendsten Studien, die es je an einer deutschen Universität gegeben hat. 40.000 Studierende waren an Deutschlands drittgrößter Universität eingeladen, Auskunft zu geben über ihre persönlichen Präferenzen im Studium, aber auch, ihre Alma Mater in Bereichen wie Studien- und Prüfungsorganisation zu bewerten.