3,872 research outputs found
Recent results on spectra and yields from NA49
The energy dependence of hadron production in central Pb+Pb collisions is presented and discussed. In particular, midrapidity m_T-spectra for pi-, K-, K+, p, bar p, d, phi, Lambda and bar Lambda at 40, 80 and 158 AGeV are shown. In addition Xi and Omega spectra are available at 158 AGeV. The spectra allow to determine the thermal freeze-out temperature T and the transverse flow velocity beta_T at the three energies. We do not observe a significant energy dependence of these parameters; furthermore there is no indication of early thermal freeze-out of Xi and Omega at 158 AGeV. Rapidity spectra for pi-, K-, K+ and phi at 40, 80 and 158 AGeV are shown, as well as first results on Omega rapidity distributions at 158 AGeV. The chemical freeze-out parameters T and mu_B at the three energies are determined from the total yields. The parameters are close to the expected phase boundary in the SPS energy range and above. Using the total yields of kaons and lambdas, the energy dependence of the strangeness to pion ratio is discussed. A maximum in this ratio is found at 40 AGeV. This maximum could indicate the formation of deconfined matter at energies above 40 AGeV. A search for open charm in a large sample of 158 AGeV events is presented. No signal is observed. This result is compared to several model predictions
Industrialization and Intergenerational Mobility in Sweden
The relationship between industrialization and intergenerational mobility has been a topic of discussion for over forty years. In this article both total mobility and relative mobility chances are studied in the decades preceding industrialization and the decades during industrialization. A high-quality data set is used covering the male population of a region in the north of Sweden during the 19th century. Total intergenerational mobility increased during industrialization until, at the end of the century, both industrialization and the growth of mobility stagnated. Sectorial barriers resulted in unequal relative mobility chances before and also during industrialization. However, sons from self-employed classes were less likely to inherit the class position of their father after the onset of industrialization. At the same time, mobility between classes differing in status became less frequent. These results show a decline in the importance of the direct transfer of resources between generations and may indicate the increasing importance of education
Heavy-ion physics studies for the Future Circular Collider
The Future Circular Collider (FCC) design study is aimed at assessing the
physics potential and the technical feasibility of a new collider with
centre-of-mass energies, in the hadron-hadron collision mode including proton
and nucleus beams, more than seven-times larger than the nominal LHC energies.
An electron-positron collider in the same tunnel is also considered as an
intermediate step, which would provide the electron-hadron option in the long
term. First ideas on the physics opportunities with heavy ions at the FCC are
presented, covering the physics of Quark-Gluon Plasma, gluon saturation,
photon-induced collisions, as well as connections with ultra-high-energy cosmic
rays.Comment: 4 pages, 3 figures, proceedings of Quark Matter 2014, Darmstadt,
Germany, submitted to Nucl. Phys.
Strangeness dynamics in relativistic nucleus-nucleus collision
We investigate hadron production as well as transverse hadron spectra in nucleus-nucleus collisions from 2 A.GeV to 21.3 A.TeV within two independent transport approaches (UrQMD and HSD) that are based on quark, diquark, string and hadronic degrees of freedom. The comparison to experimental data demonstrates that both approaches agree quite well with each other and with the experimental data on hadron production. The enhancement of pion production in central Au+Au (Pb+Pb) collisions relative to scaled pp collisions (the 'kink') is well described by both approaches without involving any phase transition. However, the maximum in the K+/Pi+ ratio at 20 to 30 A.GeV (the 'horn') is missed by ~ 40%. A comparison to the transverse mass spectra from pp and C+C (or Si+Si) reactions shows the reliability of the transport models for light systems. For central Au+Au (Pb+Pb) collisions at bombarding energies above ~ 5 A.GeV, however, the measured K +/- m-theta-spectra have a larger inverse slope parameter than expected from the calculations. The approximately constant slope of K+/-spectra at SPS (the 'step') is not reproduced either. Thus the pressure generated by hadronic interactions in the transport models above ~ 5 A.GeV is lower than observed in the experimental data. This finding suggests that the additional pressure - as expected from lattice QCD calculations at finite quark chemical potential and temperature - might be generated by strong interactions in the early pre-hadronic/partonic phase of central Au+Au (Pb+Pb) collisions
Calcifying vascular smooth muscle cells and osteoblasts: Independent cell types exhibiting extracellular matrix and biomineralization-related mimicries
Background: Ectopic vascular calcifications represent a major clinical problem associated with cardiovascular disease and mortality. However, the mechanisms underlying pathological vascular calcifications are largely unknown hampering the development of therapies to tackle this life threatening medical condition. Results: In order to gain insight into the genes and mechanisms driving this pathological calcification process we analyzed the transcriptional profile of calcifying vascular smooth muscle cells (C-VSMCs). These profiles were compared to differentiating osteoblasts, cells that constitute their physiological calcification counterparts in the body. Overall the transcriptional program of C-VSMC and osteoblasts did not overlap. Several genes, some of them relevant for bone formation, were distinctly modulated by C-VSMCs which did not necessarily lose their smooth muscle cell markers while calcifying. Bioinformatics gene clustering and correlation analysis disclosed limited bone-related mechanisms being shared by two cell types. Extracellular matrix (ECM) and biomineralization genes represented common denominators between pathological vascular and physiological bone calcifications. These genes constitute the strongest link between these cells and represent potential drivers for their shared end-point phenotype. Conclusions: The analyses support the hypothesis that VSMC trans-differentiate into C-VSMCs keeping their own identity while using mechanisms that osteoblasts use to mineralize. The data provide novel insights into groups of genes and biological processes shared in MSC and VSMC osteogenic differentiation. The distinct gene regulation between C-VSMC and osteoblasts might hold clues to find cell-specific pathway modulations, opening the possibility to tackle undesired vascular calcifications without disturbing physiologic bone formation and vice versa
Review of QGP signatures - ideas versus observables
We investigate hadron production and transverse hadron spectra in nucleus-nucleus collisions from 2 A·GeV to 21.3 A·TeV within two independent transport approaches (UrQMD and HSD) based on quark, diquark, string and hadronic degrees of freedom. The enhancement of pion production in central Au+Au (Pb+Pb) collisions relative to scaled pp collisions (the ’kink’) is described well by both approaches without involving a phase transition. However, the maximum in the K+ p+ ratio at 20 to 30 A·GeV (the ’horn’) is missed by ~ 40%. Also, at energies above ~5 A·GeV, the measured K± mT-spectra have a larger inverse slope than expected from the models. Thus the pressure generated by hadronic interactions in the transport models at high energies is too low. This finding suggests that the additional pressure - as expected from lattice QCD at finite quark chemical potential and temperature - might be generated by strong interactions in the early pre-hadronic/partonic phase of central heavy-ion collisions. Finally, we discuss the emergence of density perturbations in a first-order phase transition and why they might affect relative hadron multiplicities, collective flow, and hadron mean-free paths at decoupling. A minimum in the collective flow v2 excitation function was discovered experimentally at 40 A·GeV - such a behavior has been predicted long ago as signature for a first order phase transition
Strangeness dynamics and transverse pressure in relativistic nucleus-nucleus collisions
We investigate hadron production as well as transverse hadron spectra from proton-proton, proton-nucleus and nucleus-nucleus collisions from 2 A·GeV to 21.3 A·TeV within two independent transport approaches (HSD and UrQMD) that are based on quark, diquark, string and hadronic degrees of freedom. The comparison to experimental data on transverse mass spectra from pp, pA and C+C (or Si+Si) reactions shows the reliability of the transport models for light systems. For central Au+Au (Pb+Pb) collisions at bombarding energies above ~5 A·GeV, furthermore, the measured K± transverse mass spectra have a larger inverse slope parameter than expected from the default calculations. We investigate various scenarios to explore their potential effects on the K± spectra. In particular the initial state Cronin effect is found to play a substantial role at top SPS and RHIC energies. However, the maximum in the K+/..+ ratio at 20 to 30 A·GeV is missed by 40% and the approximately constant slope of the K± spectra at SPS energies is not reproduced either. Our systematic analysis suggests that the additional pressure - as expected from lattice QCD calculations at finite quark chemical potential µq and temperature T- should be generated by strong interactions in the early pre-hadronic/partonic phase of central Au+Au (Pb+Pb) collisions
Proteomic Analysis of Human Osteoblastic Cells: Relevant Proteins and Functional Categories for Differentiation
Abstract
Osteoblasts are the bone forming cells, capable of secreting an extracellular matrix with mineralization potential. The exact mechanism by which osteoblasts differentiate and form a mineralized extracellular matrix is presently not fully understood. To increase our knowledge about this process, we conducted proteomics analysis in human immortalized preosteoblasts (SV-HFO) able to differentiate and mineralize. We identified 381 proteins expressed during the time course of osteoblast differentiation. Gene ontology analysis revealed an overrepresentation of protein categories established as important players for osteoblast differentiation, bone formation, and mineralization such as pyrophosphatases. Proteins involved in antigen presentation, energy metabolism and cytoskeleton rearrangement constitute other overrepresented processes, whose function, albeit interesting, is not fully understood in the context of osteoblast differentiation and bone formation. Correlation analysis, based on quantitative data, revealed a biphasic osteoblast differentiation, encompassing a premineralization and a mineralization period. Identified differentially expressed proteins between mineralized and nonmineralized cells include cytoskeleton (e.g., CCT2, PLEC1, and FLNA) and extracellular matrix constituents (FN1, ANXA2, and LGALS1) among others. FT-ICR-MS data obtained for FN1, ANXA2, and LMNA shows a specific regulation of these proteins during the different phases of osteoblast differentiation. Taken together, this study increases our understanding of the proteomics changes that accompany osteoblast differentiation and may permit the discovery of novel modulators of bone formation
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