1,187 research outputs found
Fluctuations and Deconfinement Phase Transition in Nucleus-Nucleus Collisions
We propose a method to experimentally study the equation of state of strongly
interacting matter created at the early stage of nucleus--nucleus collisions.
The method exploits the relation between relative entropy and energy
fluctuations and equation of state. As a measurable quantity, the ratio of
properly filtered multiplicity to energy fluctuations is proposed. Within a
statistical approach to the early stage of nucleus-nucleus collisions, the
fluctuation ratio manifests a non--monotonic collision energy dependence with a
maximum in the domain where the onset of deconfinement occurs.Comment: revised version to be published in Phys. Lett.
Event-by-Event Fluctuations in Heavy Ion Collisions and the QCD Critical Point
The event-by-event fluctuations of suitably chosen observables in heavy ion
collisions at SPS, RHIC and LHC can tell us about the thermodynamic properties
of the hadronic system at freeze-out. By studying these fluctuations as a
function of varying control parameters, it is possible to learn much about the
phase diagram of QCD. As a timely example, we stress the methods by which
present experiments at the CERN SPS can locate the second-order critical
endpoint of the first-order transition between quark-gluon plasma and hadron
matter. Those event-by-event signatures which are characteristic of freeze-out
in the vicinity of the critical point will exhibit nonmonotonic dependence on
control parameters. We focus on observables constructed from the multiplicity
and transverse momenta of charged pions. We first consider how the
event-by-event fluctuations of such observables are affected by Bose-Einstein
correlations, by resonances which decay after freeze-out and by fluctuations in
the transverse flow velocity. We compare our thermodynamic predictions for such
noncritical event-by-event fluctuations with NA49 data, finding broad
agreement. We then focus on effects due to thermal contact between the observed
pions and a heat bath with a given (possibly singular) specific heat, and due
to the direct coupling between the critical fluctuations of the sigma field and
the observed pions. We also discuss the effect of the pions produced in the
decay of sigma particles just above threshold after freeze-out on the inclusive
pion spectrum and on multiplicity fluctuations. We estimate the size of these
nonmonotonic effects which appear near the critical point, including
restrictions imposed by finite size and finite time, and conclude that they
should be easily observable.Comment: 58 pages, 2 figures; to appear in Phys. Rev.
Dimensionality of Carbon Nanomaterials Determines the Binding and Dynamics of Amyloidogenic Peptides: Multiscale Theoretical Simulations
Experimental studies have demonstrated that nanoparticles can affect the rate of protein self-assembly, possibly interfering with the development of protein misfolding diseases such as Alzheimer's, Parkinson's and prion disease caused by aggregation and fibril formation of amyloid-prone proteins. We employ classical molecular dynamics simulations and large-scale density functional theory calculations to investigate the effects of nanomaterials on the structure, dynamics and binding of an amyloidogenic peptide apoC-II(60-70). We show that the binding affinity of this peptide to carbonaceous nanomaterials such as C60, nanotubes and graphene decreases with increasing nanoparticle curvature. Strong binding is facilitated by the large contact area available for π-stacking between the aromatic residues of the peptide and the extended surfaces of graphene and the nanotube. The highly curved fullerene surface exhibits reduced efficiency for π-stacking but promotes increased peptide dynamics. We postulate that the increase in conformational dynamics of the amyloid peptide can be unfavorable for the formation of fibril competent structures. In contrast, extended fibril forming peptide conformations are promoted by the nanotube and graphene surfaces which can provide a template for fibril-growth
Exploration of key stakeholders' preferences for pre-hospital physiologic monitoring by emergency rescue services
Peer reviewedPostprintPostprin
Slowing Out of Equilibrium Near the QCD Critical Point
The QCD phase diagram may feature a critical end point at a temperature T and
baryon chemical potential which is accessible in heavy ion collisions.
The universal long wavelength fluctuations which develop near this Ising
critical point result in experimental signatures which can be used to find the
critical point. The magnitude of the observed effects depends on how large the
correlation length becomes. Because the matter created in a heavy ion
collision cools through the critical region of the phase diagram in a finite
time, critical slowing down limits the growth of , preventing it from
staying in equilibrium. This is the fundamental nonequilibrium effect which
must be calculated in order to make quantitative predictions for experiment. We
use universal nonequilibrium dynamics and phenomenologically motivated values
for the necessary nonuniversal quantities to estimate how much the growth of
is slowed.Comment: 21 pages, 5 figures, reference added, typo corrected, to appear in
Phys. Rev.
Loss of FBP1 by Snail-Mediated Repression Provides Metabolic Advantages in Basal-Like Breast Cancer
The epithelial-mesenchymal transition (EMT) enhances cancer invasiveness and confers tumor cells with cancer stem cell (CSC)-like characteristics. We show that the Snail-G9a-Dnmt1 complex, which is critical for E-cadherin promoter silencing, is also required for the promoter methylation of fructose-1,6-biphosphatase (FBP1) in basal-like breast cancer (BLBC). Loss of FBP1 induces glycolysis and results in increased glucose uptake, macromolecule biosynthesis, formation of tetrameric PKM2, and maintenance of ATP production under hypoxia. Loss of FBP1 also inhibits oxygen consumption and reactive oxygen species production by suppressing mitochondrial complex I activity; this metabolic reprogramming results in an increased CSC-like property and tumorigenicity by enhancing the interaction of β-catenin with T-cell factor. Our study indicates that the loss of FBP1 is a critical oncogenic event in EMT and BLBC
Inhibitory effects of inhaled complex traditional Chinese medicine on early and late asthmatic responses induced by ovalbumin in sensitized guinea pigs
<p>Abstract</p> <p>Background</p> <p>Many formulae of traditional Chinese medicines (TCMs) have been used for antiasthma treatment dating back many centuries. There is evidence to suggest that TCMs are effective as a cure for this allergenic disease administered via gastric tubes in animal studies; however, their efficacy, safety and side effects as an asthmatic therapy are still unclear.</p> <p>Methods</p> <p>In this study, guinea pigs sensitized with ovalbumin (OVA) were used as an animal model for asthma challenge, and the sensitization of animals by bronchial reactivity to methacholine (Mch) and the IgE concentration in the serum after OVA challenge were estimated. Complex traditional Chinese herbs (CTCM) were administered to the animals by nebulization, and the leukocytes were evaluated from bronchoalveolar lavage fluid (BALF).</p> <p>Results</p> <p>The results showed that inhalation of CTCM could abolish the increased lung resistance (13-fold increase) induced by challenge with OVA in the early asthmatic response (EAR), reducing to as low as baseline (1-fold). Moreover, our results indicated higher IgE levels (range, 78-83 ng/ml) in the serum of sensitized guinea pigs than in the unsensitized controls (0.9 ± 0.256 ng/ml). In addition, increased total leukocytes and higher levels of eosinophils and neutrophils were seen 6 hours after challenge, and the increased inflammatory cells were reduced by treatment with CTCM inhalation. The interleukin-5 (IL-5) level in BALF was also reduced by CTCM.</p> <p>Conclusion</p> <p>Our findings indicate a novel method of administering traditional Chinese medicines for asthma treatment in an animal model that may be more effective than traditional methods.</p
Complex patterns of local adaptation in teosinte
Populations of widely distributed species often encounter and adapt to
specific environmental conditions. However, comprehensive characterization of
the genetic basis of adaptation is demanding, requiring genome-wide genotype
data, multiple sampled populations, and a good understanding of population
structure. We have used environmental and high-density genotype data to
describe the genetic basis of local adaptation in 21 populations of teosinte,
the wild ancestor of maize. We found that altitude, dispersal events and
admixture among subspecies formed a complex hierarchical genetic structure
within teosinte. Patterns of linkage disequilibrium revealed four mega-base
scale inversions that segregated among populations and had altitudinal clines.
Based on patterns of differentiation and correlation with environmental
variation, inversions and nongenic regions play an important role in local
adaptation of teosinte. Further, we note that strongly differentiated
individual populations can bias the identification of adaptive loci. The role
of inversions in local adaptation has been predicted by theory and requires
attention as genome-wide data become available for additional plant species.
These results also suggest a potentially important role for noncoding
variation, especially in large plant genomes in which the gene space represents
a fraction of the entire genome
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