38,849 research outputs found
Affleck-Dine Baryogenesis, Split Supersymmetry, and Inflation
It is shown that, in the context of split supersymmetry, a simple model with
a single complex scalar field can produce chaotic inflation and generate the
observed amount of baryon asymmetry via the Affleck-Dine mechanism. While the
inflaton quantum fluctuations give rise to curvature perturbation, we show that
quantum fluctuations of the phase of the scalar field can produce baryonic
isocurvature perturbation. Combining with constraints from WMAP data, all
parameters in the model can be determined to within a narrow range.Comment: version accepted for publication in PR
Anomalous diffusion in polymers: long-time behaviour
We study the Dirichlet boundary value problem for viscoelastic diffusion in
polymers. We show that its weak solutions generate a dissipative semiflow. We
construct the minimal trajectory attractor and the global attractor for this
problem.Comment: 13 page
Common Genetic Variant Association with Altered HLA Expression, Synergy with Pyrethroid Exposure, and Risk for Parkinson's Disease: An Observational and Case-Control Study.
Background/objectivesThe common non-coding single nucleotide polymorphism (SNP) rs3129882 in HLA-DRA is associated with risk for idiopathic Parkinson's disease (PD). The location of the SNP in the major histocompatibility complex class II (MHC-II) locus implicates regulation of antigen presentation as a potential mechanism by which immune responses link genetic susceptibility to environmental factors in conferring lifetime risk for PD.MethodsFor immunophenotyping, blood cells from 81 subjects were analyzed by qRT-PCR and flow cytometry. A case-control study was performed on a separate cohort of 962 subjects to determine association of pesticide exposure and the SNP with risk of PD.ResultsHomozygosity for G at this SNP was associated with heightened baseline expression and inducibility of MHC class II molecules in B cells and monocytes from peripheral blood of healthy controls and PD patients. In addition, exposure to a commonly used class of insecticide, pyrethroids, synergized with the risk conferred by this SNP (OR = 2.48, p = 0.007), thereby identifying a novel gene-environment interaction that promotes risk for PD via alterations in immune responses.ConclusionsIn sum, these novel findings suggest that the MHC-II locus may increase susceptibility to PD through presentation of pathogenic, immunodominant antigens and/or a shift toward a more pro-inflammatory CD4+ T cell response in response to specific environmental exposures, such as pyrethroid exposure through genetic or epigenetic mechanisms that modulate MHC-II gene expression
The Proctolin Gene and Biological Effects of Proctolin in the Blood-Feeding Bug, Rhodnius prolixus
We have reinvestigated the possible presence or absence of the pentapeptide proctolin in Rhodnius prolixus and report here the cloning of the proctolin cDNA. The transcript is expressed in the central nervous system (CNS) and some peripheral tissues. The proctolin prepropeptide encodes a single copy of proctolin along with a possible proctolin-precursor-associated peptide. We have biochemically identified proctolin in CNS extracts and shown its distribution using proctolin-like immunoreactivity. Immunostained processes are found on the salivary glands, female and male reproductive tissues, and heart and associated alary muscles. Proctolin-like immunoreactive bipolar neurons are found on the lateral margins of the common oviduct and bursa. Proctolin is biologically active on R. prolixus tissues, stimulating increases in contraction of anterior midgut and hindgut muscles, and increasing heartbeat frequency. Contrary to the previous suggestion that proctolin is absent from R. prolixus, proctolin is indeed present and biologically active in this medically important bug
Influence on electron coherence from quantum electromagnetic fields in the presence of conducting plates
The influence of electromagnetic vacuum fluctuations in the presence of the
perfectly conducting plate on electrons is studied with an interference
experiment. The evolution of the reduced density matrix of the electron is
derived by the method of influence functional. We find that the plate boundary
anisotropically modifies vacuum fluctuations that in turn affect the electron
coherence. The path plane of the interference is chosen either parallel or
normal to the plate. In the vicinity of the plate, we show that the coherence
between electrons due to the boundary is enhanced in the parallel
configuration, but reduced in the normal case. The presence of the second
parallel plate is found to boost these effects. The potential relation between
the amplitude change and phase shift of interference fringes is pointed out.
The finite conductivity effect on electron coherence is discussed.Comment: 29 pages, 3 figure
A Holographic Model of Strange Metals
We give a review on our recent work arXiv:1006.0779 [hep-th] and
arXiv:1006.1719 [hep-th], in which properties of holographic strange metals
were investigated. The background is chosen to be anisotropic scaling solution
in Einstein-Maxwell-Dilaton theory with a Liouville potential. The effects of
bulk Maxwell field, an extra U(1) gauge field and probe D-branes on the DC
conductivity, the DC Hall conductivity and the AC conductivity are extensively
analyzed. We classify behaviors of the conductivities according to the
parameter ranges in the bulk theory and characterize conditions when the
holographic results can reproduce experimental data.Comment: 34 pages, 15 figures, minor correction
Multi-Scale Simulation Modeling for Prevention and Public Health Management of Diabetes in Pregnancy and Sequelae
Diabetes in pregnancy (DIP) is an increasing public health priority in the
Australian Capital Territory, particularly due to its impact on risk for
developing Type 2 diabetes. While earlier diagnostic screening results in
greater capacity for early detection and treatment, such benefits must be
balanced with the greater demands this imposes on public health services. To
address such planning challenges, a multi-scale hybrid simulation model of DIP
was built to explore the interaction of risk factors and capture the dynamics
underlying the development of DIP. The impact of interventions on health
outcomes at the physiological, health service and population level is measured.
Of particular central significance in the model is a compartmental model
representing the underlying physiological regulation of glycemic status based
on beta-cell dynamics and insulin resistance. The model also simulated the
dynamics of continuous BMI evolution, glycemic status change during pregnancy
and diabetes classification driven by the individual-level physiological model.
We further modeled public health service pathways providing diagnosis and care
for DIP to explore the optimization of resource use during service delivery.
The model was extensively calibrated against empirical data.Comment: 10 pages, SBP-BRiMS 201
Symmetry energy of dense matter in holographic QCD
We study the nuclear symmetry energy of dense matter using holographic QCD.
To this end, we consider two flavor branes with equal quark masses in a
D4/D6/D6 model. We find that at all densities the symmetry energy monotonically
increases. At small densities, it exhibits a power law behavior with the
density, .Comment: 9 pages, 3 figure
Direct exfoliation and dispersion of two-dimensional materials in pure water via temperature control
The high-volume synthesis of two-dimensional (2D) materials in the form of platelets is desirable for various applications. While water is considered an ideal dispersion medium, due to its abundance and low cost, the hydrophobicity of platelet surfaces has prohibited its widespread use. Here we exfoliate 2D materials directly in pure water without using any chemicals or surfactants. In order to exfoliate and disperse the materials in water, we elevate the temperature of the sonication bath, and introduce energy via the dissipation of sonic waves. Storage stability greater than one month is achieved through the maintenance of high temperatures, and through atomic and molecular level simulations, we further discover that good solubility in water is maintained due to the presence of platelet surface charges as a result of edge functionalization or intrinsic polarity. Finally, we demonstrate inkjet printing on hard and flexible substrates as a potential application of water-dispersed 2D materials.close1
Geometrically-controlled twist transitions in nematic cells
We study geometrically-controlled twist transitions of a nematic confined
between a sinusoidal grating and a flat substrate. In these cells the
transition to the twisted state is driven by surface effects. We have
identified the mechanisms responsible for the transition analytically and used
exact numerical calculations to study the range of surface parameters where the
twist instability occurs. Close to these values the cell operates under minimal
external fields or temperature variations
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