The measurement of the production of charm jets, identified by the presence of a D$^{0}$ meson in the jet constituents, is presented in proton–proton collisions at centre-of-mass energies of $ ...\sqrt{s} $ = 5.02 and 13 TeV with the ALICE detector at the CERN LHC. The D$^{0}$ mesons were reconstructed from their hadronic decay D$^{0}$ → K$^{−}$π$^{+}$ and the respective charge conjugate. Jets were reconstructed from D$^{0}$-meson candidates and charged particles using the anti-k$_{T}$ algorithm, in the jet transverse momentum range 5 < p$_{T,chjet}$< 50 GeV/c, pseudorapidity |η$_{jet}$| < 0.9 − R, and with the jet resolution parameters R = 0.2, 0.4, 0.6. The distribution of the jet momentum fraction carried by a D$^{0}$ meson along the jet axis $ \left({z}_{\Big\Vert}^{\textrm{ch}}\right) $ was measured in the range 0.4 <$ {z}_{\Big\Vert}^{\textrm{ch}} $< 1.0 in four ranges of the jet transverse momentum. Comparisons of results for different collision energies and jet resolution parameters are also presented. The measurements are compared to predictions from Monte Carlo event generators based on leading-order and next-to-leading-order perturbative quantum chromodynamics calculations. A generally good description of the main features of the data is obtained in spite of a few discrepancies at low p$_{T,chjet}$. Measurements were also done for R = 0.3 at $ \sqrt{s} $ = 5.02 and are shown along with their comparisons to theoretical predictions in an appendix to this paper.graphic not available: see fulltext
The first measurement of the production of pions, kaons, (anti-)protons and ϕ mesons at midrapidity in Xe–Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV is presented. Transverse momentum ...(pT) spectra and pT-integrated yields are extracted in several centrality intervals bridging from p–Pb to mid-central Pb–Pb collisions in terms of final-state multiplicity. The study of Xe–Xe and Pb–Pb collisions allows systems at similar charged-particle multiplicities but with different initial geometrical eccentricities to be investigated. A detailed comparison of the spectral shapes in the two systems reveals an opposite behaviour for radial and elliptic flow. In particular, this study shows that the radial flow does not depend on the colliding system when compared at similar charged-particle multiplicity. In terms of hadron chemistry, the previously observed smooth evolution of particle ratios with multiplicity from small to large collision systems is also found to hold in Xe–Xe. In addition, our results confirm that two remarkable features of particle production at LHC energies are also valid in the collision of medium-sized nuclei: the lower proton-to-pion ratio with respect to the thermal model expectations and the increase of the ϕ-to-pion ratio with increasing final-state multiplicity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification ...and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/ in p–Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.
The exploration of the phase diagram of Quantum ChromoDynamics (QCD) is
carried out by studying ultrarelativistic heavy-ion collisions. The energy
range covered by the CERN SPS ($\sqrt{s_{\rm ...\scriptscriptstyle{NN}}} \sim$
6-17 GeV) is ideal for the investigation of the region of the phase diagram
corresponding to finite baryochemical potential ($\mu_{\rm B}$), and has been
little explored up to now. We propose in this document a new experiment, NA60+,
that would address several observables which are fundamental for the
understanding of the phase transition from hadronic matter towards a
Quark-Gluon Plasma (QGP) at SPS energies. In particular, we propose to study,
as a function of the collision energy, the production of thermal dimuons from
the created system, from which one would obtain a caloric curve of the QCD
phase diagram that is sensitive to the order of the phase transition. In
addition, the measurement of a $\rho$-a$_1$ mixing contribution would provide
conclusive insights into the restoration of the chiral symmetry of QCD. In
parallel, studies of heavy quark and quarkonium production would also be
carried out, addressing the measurement of transport properties of the QGP and
the investigation of the onset of the deconfinement transition. The document
also defines an experimental set-up which couples a vertex telescope based on
monolithic active pixel sensors (MAPS) to a muon spectrometer with tracking
(GEM) and triggering (RPC) detectors within a large acceptance toroidal magnet.
Results of physics performance studies for most observables accessible to NA60+
are discussed, showing that the results of the experiment would lead to a
significant advance of our understanding of strong interaction physics. The
document has been submitted as an input to the European Particle Physics
Strategy Update 2018-2020 (http://europeanstrategyupdate.web.cern.ch/).
The exploration of the phase diagram of Quantum ChromoDynamics (QCD) is carried out by studying ultrarelativistic heavy-ion collisions. The energy range covered by the CERN SPS (\(\sqrt{s_{\rm ...\scriptscriptstyle{NN}}} \sim\) 6-17 GeV) is ideal for the investigation of the region of the phase diagram corresponding to finite baryochemical potential (\(\mu_{\rm B}\)), and has been little explored up to now. We propose in this document a new experiment, NA60+, that would address several observables which are fundamental for the understanding of the phase transition from hadronic matter towards a Quark-Gluon Plasma (QGP) at SPS energies. In particular, we propose to study, as a function of the collision energy, the production of thermal dimuons from the created system, from which one would obtain a caloric curve of the QCD phase diagram that is sensitive to the order of the phase transition. In addition, the measurement of a \(\rho\)-a\(_1\) mixing contribution would provide conclusive insights into the restoration of the chiral symmetry of QCD. In parallel, studies of heavy quark and quarkonium production would also be carried out, addressing the measurement of transport properties of the QGP and the investigation of the onset of the deconfinement transition. The document also defines an experimental set-up which couples a vertex telescope based on monolithic active pixel sensors (MAPS) to a muon spectrometer with tracking (GEM) and triggering (RPC) detectors within a large acceptance toroidal magnet. Results of physics performance studies for most observables accessible to NA60+ are discussed, showing that the results of the experiment would lead to a significant advance of our understanding of strong interaction physics. The document has been submitted as an input to the European Particle Physics Strategy Update 2018-2020 (http://europeanstrategyupdate.web.cern.ch/).
Rationale
Ghrelin (Ghr) is a peptide that participates in the modulation of several biological processes. Ghr administration into the hippocampus improves learning and memory in different memory ...tests. However, the possible mechanisms underlying this effect on memory have not yet been clarified.
Objective
The purpose of the present work is to add new insights about the mechanisms by which Ghr modulates long-term memory consolidation in the hippocampus. We examined Ghr effects upon processes related to increased synaptic efficacy as presynaptic glutamate release and changes in the expression of the NR2B-subunits containing
n
-methyl-d-aspartate receptors (NMDAR), which are critical for LTP induction. We also attempted to determine the temporal window in which Ghr administration induces memory facilitation and if the described effects depend on GHS-R1a stimulation.
Results
The present research demonstrated that Ghr increased glutamate release from hippocampal synaptosomes; intra-hippocampal Ghr administration increased NR2B-subunits expression in CA1 and DG subareas and also reversed the deleterious effects of the NR2B-subunit-specific antagonist, Ro 25-6981, upon memory consolidation and LTP generation in the hippocampus. These effects are likely to be the consequence of GHS-R1a activation.
Conclusion
According to the results above mentioned and previous findings, we can hypothesize some of the mechanisms by which Ghr modulates memory consolidation. At presynaptic level, Ghr stimulates glutamate release, probably by enhancing Ca
2+
i
. At postsynaptic level, the glutamate released activates NMDAR while Ghr also mediates effects directly activating its specific receptors and increases NR2B-subunit expression.
•Gr increases DS density in cultured hippocampal neurons.•Gr increases DS density in hippocampus (Hp) after “in vivo” icv administration.•The increase in DS density is accompanied by changes in spine ...morphology.•Gr enhances the expression of specific BDNF-mRNA species in Hp.
Ghrelin (Gr) is an orexigenic peptide that acts via its specific receptor, GHSR-1a distributed throughout the brain, being mainly enriched in pituitary, cortex and hippocampus (Hp) modulating a variety of brain functions. Behavioral, electrophysiological and biochemical evidence indicated that Gr modulates the excitability and the synaptic plasticity in Hp. The present experiments were designed in order to extend the knowledge about the Gr effect upon structural synaptic plasticity since morphological and quantitative changes in spine density after Gr administration were analyzed “in vitro” and “in vivo”. The results show that Gr administered to hippocampal cultures or stereotactically injected in vivo to Thy-1 mice increases the density of dendritic spines (DS) being the mushroom type highly increased in secondary and tertiary extensions. Spines classified as thin type were increased particularly in primary extensions. Furthermore, we show that Gr enhances selectively the expression of BDNF-mRNA species.
Abstract A 13-amino acid peptide named neuronostatin (NST) encoded in the somatostatin pro-hormone has been recently reported. It is produced throughout the body, particularly in brain areas that ...have significant actions over the metabolic and autonomic regulation. The present study was performed in order to elucidate the functional role of NST on memory, anxiety-like behavior and food intake and the hippocampal participation in these effects. When the peptide was intra-hippocampally administered at 3.0 nmol/μl, it impaired memory retention in both, object recognition and step-down test. Also, this dose blocked the hippocampal long-term potentiation (LTP) generation. When NST was intra-hippocampally administered at 0.3 nmol/μl and 3.0 nmol/μl, anxiolytic effects were observed. Also, the administration in the third ventricle at the higher dose (3.0 nmol/μl) induced similar effects, and both doses reduced food intake. The main result of the present study is the relevance of the hippocampal formation in the behavioral effects induced by NST, and these effects could be associated to a reduced hippocampal synaptic plasticity.
G protein–coupled receptors (GPCRs) are a class of integral membrane proteins mediating intercellular interactions of fundamental physiological importance for survival including regulation of food ...intake, blood pressure, and hormonal sensing signaling, among other roles. Homeostatic alterations in the physiological status of GPCRs are often associated with underlying causes of disease, and to date, several orphan GPCRs are still uncharacterized.
Findings from our previous study demonstrate that the Rhodopsin family protein GPR162 is widely expressed in GABAergic as well as other neurons within the mouse hippocampus, whereas extensive expression is observed in hypothalamus, amygdala, and ventral tegmental area, regions strictly interconnected and involved in the regulation of energy homeostasis and hedonic feeding.
In this study, we provide a further anatomical characterization of GPR162 in mouse brain via in situ hybridization as well as detailed mRNA expression in a panel of rat tissues complementing a specie-specific mapping of the receptor. We also provide an attempt to demonstrate a functional implication of GPR162 in food intake-related behavior via antisense knockdown studies. Furthermore, we performed human genetic studies in which for the first time, variants of the GPR162 gene were associated with impairments in glucose homeostasis.
•We completed the anatomical characterization of GPR162 complementing a species-specific mapping of the gene in both mouse and rat.•We reported a functional implication of GPR162 in food intake-related behavior via antisense knockdown studies.•Variants of the GPR162 gene are associated with impairments in glucose homeostasis in two Swedish cohorts.
