2,657 research outputs found
Hamiltonian lattice quantum chromodynamics at finite density with Wilson fermions
Quantum chromodynamics (QCD) at sufficiently high density is expected to
undergo a chiral phase transition. Understanding such a transition is of
particular importance for neutron star or quark star physics. In Lagrangian
SU(3) lattice gauge theory, the standard approach breaks down at large chemical
potential , due to the complex action problem. The Hamiltonian formulation
of lattice QCD doesn't encounter such a problem. In a previous work, we
developed a Hamiltonian approach at finite chemical potential and
obtained reasonable results in the strong coupling regime. In this paper, we
extend the previous work to Wilson fermions. We study the chiral behavior and
calculate the vacuum energy, chiral condensate and quark number density, as
well as the masses of light hadrons. There is a first order chiral phase
transition at zero temperature.Comment: 23 pages. Version accepted for publication in Physical Review
Comparison of perceptual learning of real and virtual line orientations: An event-related potential study
AbstractWhen investigating perceptual learning (PL), most researchers use real figures as stimuli, but PL can occur when subjects are trained with virtual stimuli or even without any visual stimuli at all. Here, we first demonstrated that virtual lines have the same perceptual attributes as real lines by confirming that there is also an oblique effect in virtual lines (formed by a pair of circles) in an orientation discrimination task. Then, our ERP study showed that orientation discrimination learning and its transfer across real and virtual lines were associated with more negative parietal–occipital P1–N1 (reduced P1 and enhanced N1), which indicated the involvement of high-level stages of visual information processing or the involvement of top-down influences. At the same time, the specific ERP changes in the frontal ERP components were differently associated with real versus virtual line orientation learning. That is, real line learning was characterized by an early and short-lasting frontal N1 (120–140ms) reduction, in contrast to a much later, widespread, and long-lasting P150–300 decrease in virtual line learning. These results contribute to the understanding of the neural basis of perceptual learning and the distinction between real and virtual stimulus learning
Generating scalable entanglement of ultracold bosons in superlattices through resonant shaking
Based on a one-dimensional double-well superlattice with a unit filling of
ultracold atoms per site, we propose a scheme to generate scalable entangled
states in the superlattice through resonant lattice shakings. Our scheme
utilizes periodic lattice modulations to entangle two atoms in each unit cell
with respect to their orbital degree of freedom, and the complete atomic system
in the superlattice becomes a cluster of bipartite entangled atom pairs. To
demonstrate this we perform quantum dynamical simulations using
the Multi-Layer Multi-Configuration Time-Dependent Hartree Method for Bosons,
which accounts for all correlations among the atoms. The proposed clusters of
bipartite entanglements manifest as an essential resource for various quantum
applications, such as measurement based quantum computation. The lattice
shaking scheme to generate this cluster possesses advantages such as a high
scalability, fast processing speed, rich controllability on the target
entangled states, and accessibility with current experimental techniques.Comment: 13 pages, 3 figure
Prevalence survey on pterygium among people aged 40 and above in Hengli Town of Dongguan
AIM:To investigate the prevalence of pterygium of the household population aged 40 and above in Hengli Town of Dongguan.<p>METHODS: Using the method of cluster random sampling, select 3 628 people aged 40 and above in four villages and one community for visual examination, intraocular pressure check, slit lamp examination and questionnaire.<p>RESULTS: The actual number of subjects was 3 393 people, and examination rate was 93.52%. We detected 843 patients with pterygium. The prevalence of pterygium was 24.85%.<p>CONCLUSION: There is high prevalence of pterygium in Dongguan area. The prevalence of pterygium is related with age and working environment, but has no relation with gender
Complexity Analysis and Parameter Estimation of Dynamic Metabolic Systems
A metabolic system consists of a number of reactions transforming molecules of one kind into another to provide the energy that living cells need. Based on the biochemical reaction principles, dynamic metabolic systems can be modeled by a group of coupled differential equations which consists of parameters, states (concentration of molecules involved), and reaction rates. Reaction rates are typically either polynomials or rational functions in states and constant parameters. As a result, dynamic metabolic systems are a group of differential equations nonlinear and coupled in both parameters and states. Therefore, it is challenging to estimate parameters in complex dynamic metabolic systems. In this paper, we propose a method to analyze the complexity of dynamic metabolic systems for parameter estimation. As a result, the estimation of parameters in dynamic metabolic systems is reduced to the estimation of parameters in a group of decoupled rational functions plus polynomials (which we call improper rational functions) or in polynomials. Furthermore, by taking its special structure of improper rational functions, we develop an efficient algorithm to estimate parameters in improper rational functions. The proposed method is applied to the estimation of parameters in a dynamic metabolic system. The simulation results show the superior performance of the proposed method
Isospin dependence of projectile-like fragment production at intermediate energies
The cross sections of fragments produced in 140 MeV Ca + Be
and Ni + Be reactions are calculated by the statistical
abration-ablation(SAA) model and compared to the experimental results measured
at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State
University. The fragment isotopic and isotonic cross section distributions of
Ca and Ca, Ni and Ni, Ca and Ni, and
Ca and Ni are compared and the isospin dependence of the
projectile fragmentation is studied. It is found that the isospin dependence
decreases and disappears in the central collisions. The shapes of the fragment
isotopic and isotonic cross section distributions are found to be very similar
for symmetric projectile nuclei. The shapes of the fragment isotopic and
isotonic distributions of different asymmetric projectiles produced in
peripheral reactions are found very similar. The similarity of the
distributions are related to the similar proton and neutron density
distributions inside the nucleus in framework of the SAA model.Comment: 7 pages, 4 figures; to be published in Phys Rev
Global Proteomic Analysis of the Resuscitation State of Vibrio parahaemolyticus Compared With the Normal and Viable but Non-culturable State
Vibrio parahaemolyticus is a common pathogen which has become a major concern of seafood products. The bacteria in the viable but non-culturable (VBNC) state are unable to form colonies on growth media, but under appropriate conditions they can regain culturability. In this study, V. parahaemolyticus was induced into VBNC state at low temperature and oligotrophic condition, and was resuscitated to culturable state. The aim of this study is to explore the comparative proteomic profiles of the resuscitation state compared with the VBNC state and the exponential phase of V. parahaemolyticus using isobaric tags for relative and absolute quantitation (iTRAQ) technique. The differentially expressed proteins (DEPs) were subjected to GO functional annotations and KEGG pathway analysis. The results indicated that a total of 429 proteins were identified as the significant DEPs in the resuscitation cells compared with the VBNC cells, including 330 up-regulated and 99 down-regulated DEPs. Meanwhile, the resuscitation cells displayed 25 up-regulated and 36 down-regulated DEPs (total of 61 DEPs) in comparison with the exponential phase cells. The remarkable DEPs including ribosomal proteins, ABC transporters, outer membrane proteins and flagellar proteins. GO annotation showed that the 429 DEPs were classified into 37 GO terms, of which 17 biological process (BP) terms, 9 cellular component (CC) terms and 11 molecular function (MF) terms. The up-regulated proteins presented in all GO terms except two terms of developmental process and reproduction. The 61 DEPs were assigned to 23 GO terms, the up- and down-regulated DEPs were both mainly involved in cellular process, establishment of localization, metabolic process and so on. KEGG pathway analysis revealed that the 429 DEPs were assigned to 35 KEGG pathways, and the pathways of ribosome, glyoxylate and dicarboxylate metabolism were significantly enriched. Moreover, the 61 DEPs located in 26 KEGG pathways, including the significantly enriched KEGG pathways of ABC transporters and two-component system. This study would contribute to a better understanding of the molecular mechanism underlying the resuscitation of the VBNC state of V. parahaemolyticus
MCP-1, ICAM-1 and VCAM-1 are present in early aneurysmal dilatation in experimental rats.
Recent studies have suggested that inflammation actively participates in ascending aortic aneurysm formation. The aim of the present study was to evaluate the expression changes of adhesion molecules and MMPs in an experimental model of ascending aortic aneurysm induced by ascending aorta banding in Wistar rats. Twelve rats developed aortic dilation after ascending aorta banding treatment, while nine normal animals underwent surgery without banding were used as controls. Light microscope and scanning electron microscope showed that the wall of the ascending aorta became disorganized as well as infiltration by inflammatory cells in aneurysmal rats. By using immunohistochemical techniques, a significant increase in the immunostaining of MCP-1 was observed in the aneurysmal wall as compared to the normal aortic wall. Under similar experimental conditions, we also found that the immunostaining of ICAM-1 and VCAM-1 was markedly increased in the aneurysmal wall. In addition, gelatin zymographic analysis showed that the expression and activities of MMP-2 and MMP-9 were remarkably enhanced in the ascending aorta of ascending aortic aneurysmal rats as compared to normal rats. These results demonstrate that MCP-1, ICAM-1 and VCAM-1 are involved in the pathogenesis of ascending aortic aneurysm and an increase in the immunostaining and activity of MMP-2 and MMP-9 may promote the progression of ascending aortic aneurysm
The UDP-glucosyltransferase multigene family in Bombyx mori
<p>Abstract</p> <p>Background</p> <p>Glucosidation plays a major role in the inactivation and excretion of a great variety of both endogenous and exogenous compounds. A class of UDP-glycosyltransferases (UGTs) is involved in this process. Insect UGTs play important roles in several processes, including detoxication of substrates such as plant allelochemicals, cuticle formation, pigmentation, and olfaction. Identification and characterization of <it>Bombyx mori </it>UGT genes could provide valuable basic information for this important family and explain the detoxication mechanism and other processes in insects.</p> <p>Results</p> <p>Taking advantage of the newly assembled genome sequence, we performed a genome-wide analysis of the candidate UGT family in the silkworm, <it>B. mori</it>. Based on UGT signature and their similarity to UGT homologs from other organisms, we identified 42 putative silkworm UGT genes. Most of them are clustered on the silkworm chromosomes, with two major clusters on chromosomes 7 and 28, respectively. The phylogenetic analysis of these identified 42 UGT protein sequences revealed five major groups. A comparison of the silkworm UGTs with homologs from other sequenced insect genomes indicated that some UGTs are silkworm-specific genes. The expression patterns of these candidate genes were investigated with known expressed sequence tags (ESTs), microarray data, and RT-PCR method. In total, 36 genes were expressed in tissues examined and showed different patterns of expression profile, indicating that these UGT genes might have different functions.</p> <p>Conclusion</p> <p><it>B. mori </it>possesses a largest insect UGT gene family characterized to date, including 42 genes. Phylogenetic analysis, genomic organization and expression profiles provide an overview for the silkworm UGTs and facilitate their functional studies in future.</p
Manifold formation and crossings of ultracold lattice spinor atoms in the intermediate interaction regime
Ultracold spinor atoms in the weak and strong interaction regime have
received extensive investigations, while the behavior in the intermediate
regime is less understood. We numerically investigate ultracold spinor atomic
ensembles of finite size in the intermediate interaction regime, and reveal the
evolution of the eigenstates from the strong to the intermediate regime. In the
strong interaction regime, it has been well known that the low-lying
eigenenergy spectrum presents the well-gaped multi-manifold structure, and the
energy gaps protect the categorization of the eigenstates. In the intermediate
interaction regime, it is found that the categorization of the eigenstates is
preserved, and the eigenenergy spectrum become quasi-continuum, with different
manifolds becoming overlapped. The overlapping induces both direct and avoided
crossings between close-lying manifolds, which is determined by the combined
symmetries of the eigenstates involved in the crossing. A modified t-J model is
derived to describe the low-lying eigenstates in the intermediate regime, which
can capture the formation and crossings of the manifolds. State preparation
through the avoided crossings is also investigated.Comment: 8 pages,6 figure
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