862 research outputs found
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Suppression of the primary immune response in rainbow trout, Salmo gairdneri, sublethally irradiated during embryogenesis
Variational Monte Carlo Study of Spin-Gapped Normal State and BCS-BEC Crossover in Two-Dimensional Attractive Hubbard Model
We study properties of normal, superconducting (SC) and CDW states for an
attractive Hubbard model on the square lattice, using a variational Monte Carlo
method. In trial wave functions, we introduce an interspinon binding factor,
indispensable to induce a spin-gap transition in the normal state, in addition
to the onsite attractive and intersite repulsive factors. It is found that, in
the normal state, as the interaction strength increases, a first-order
spin-gap transition arises at (: band width) from a
Fermi liquid to a spin-gapped state, which is conductive through hopping of
doublons. In the SC state, we confirm by analysis of various quantities that
the mechanism of superconductivity undergoes a smooth crossover at around
|U_{\ma{co}}|\sim |U_{\rm c}| from a BCS type to a Bose-Einstein condensation
(BEC) type, as increases. For |U|<|U_{\ma{co}}|, quantities such as
the condensation energy, a SC correlation function and the condensate fraction
of onsite pairs exhibit behavior of , as expected from the
BCS theory. For |U|>|U_{\ma{co}}|, quantities such as the energy gain in the
SC transition and superfluid stiffness, which is related to the cost of phase
coherence, behave as , as expected in a bosonic
scheme. In this regime, the SC transition is induced by a gain in kinetic
energy, in contrast with the BCS theory. We refer to the relevance to the
pseudogap in cuprate superconductors.Comment: 14 pages, 22 figures, submitted to Journal of the Physical Society of
Japa
Low temperature properties of the fermionic mixtures with mass imbalance in optical lattice
We study the attractive Hubbard model with mass imbalance to clarify low
temperature properties of the fermionic mixtures in the optical lattice. By
combining dynamical mean-field theory with the continuous-time quantum Monte
Carlo simulation, we discuss the competition between the superfluid and density
wave states at half filling. By calculating the energy and the order parameter
for each state, we clarify that the coexisting (supersolid) state, where the
density wave and superfluid states are degenerate, is realized in the system.
We then determine the phase diagram at finite temperatures.Comment: 5 pages, 4 figures, accepted for publication in J. Phys. Soc. Jp
Hierarchically Porous Gd3+-Doped CeO2 Nanostructures for the Remarkable Enhancement of Optical and Magnetic Properties
Rare earth ion-doped CeO2 has attracted more and more attention because of its special electrical, optical, magnetic, or catalytic properties. In this paper, a facile electrochemical deposition route was reported for the direct growth of the porous Gd-doped CeO2. The formation process of Gd-doped CeO2 composites was investigated. The obtained deposits were characterized by SEM, EDS, XRD, and XPS. The porous Gd3+- doped CeO2 (10 at% Gd) displays a typical type I adsorption isotherm and yields a large specific surface area of 135 m2/g. As Gd3+ ions were doped into CeO2 lattice, the absorption spectrum of Gd3+-doped CeO2 nanocrystals exhibited a red shift compared with porous CeO2 nanocrystals and bulk CeO2, and the luminescence of Gd3+-doped CeO2 deposits was remarkably enhanced due to the presence of more oxygen vacancies. In addition, the strong magnetic properties of Gd-doped CeO2 (10 at% Gd) were observed, which may be caused by Gd3+ ions or more oxygen defects in deposits. In addition, the catalytic activity of porous Gd-doped CeO2 toward CO oxidation was studied
Flavoured soft leptogenesis and natural values of the B term
We revisit flavour effects in soft leptogenesis relaxing the assumption of
universality for the soft supersymmetry breaking terms. We find that with
respect to the case in which the heavy sneutrinos decay with equal rates and
equal CP asymmetries for all lepton flavours, hierarchical flavour
configurations can enhance the efficiency by more than two orders of magnitude.
This translates in more than three order of magnitude with respect to the
one-flavour approximation. We verify that lepton flavour equilibration effects
related to off-diagonal soft slepton masses are ineffective for damping these
large enhancements. We show that soft leptogenesis can be successful for
unusual values of the relevant parameters, allowing for and for values of the washout parameter up to .Comment: 23 pages, 5 figures postscript, Minor changes to match the published
version in JHE
The environmental impact of fertilizer embodied in a wheat-to-bread supply chain
Food production and consumption cause approximately one-third of total greenhouse gas emissions, and therefore delivering food security challenges not only the capacity of our
agricultural system, but also its environmental sustainability. Knowing where and at what level environmental impacts
occur within particular food supply chains is necessary if
farmers, agri-food industries and consumers are to share
responsibility to mitigate these impacts. Here we present
an analysis of a complete supply chain for a staple of the
global diet, a loaf of bread. We obtained primary data for all
the processes involved in the farming, production and transport
systems that lead to the manufacture of a particular brand of
800 g loaf. The data were analysed using an advanced life
cycle assessment (LCA) tool, yielding metrics of environmental
impact, including greenhouse gas emissions. We show
that more than half of the environmental impact of producing
the loaf of bread arises directly from wheat cultivation, with
the use of ammonium nitrate fertilizer alone accounting for
around 40%. These findings reveal the dependency of bread
production on the unsustainable use of fertilizer and illustrate
the detail needed if the actors in the supply chain are to
assume shared responsibility for achieving sustainable
food production
Supersolid state of ultracold fermions in an optical lattice
We study ultracold fermionic atoms trapped in an optical lattice with
harmonic confinement by means of the dynamical mean-field approximation. It is
demonstrated that a supersolid state, where an s-wave superfluid coexists with
a density-wave state with a checkerboard pattern, is stabilized by attractive
onsite interactions on a square lattice. Our new finding here is that a
confining potential plays an invaluable role in stabilizing the supersolid
state. We establish a rich phase diagram at low temperatures, which clearly
shows how the insulator, the density wave and the superfluid compete with each
other to produce an intriguing domain structure. Our results shed light on the
possibility of the supersolid state in fermionic optical lattice systems.Comment: 5 pages, 4 figure
Study and Search for Main Reason of Lung Cancers Based on Cherenkov Radiation in Environmental Radiation
The number of lung-cancer-related death is highest among all cancers in the world, and it is increasing in Japan where population aging in progressing. The main reason for the lung cancer of non-smokers is regarded to be environmental pollution or exposure of the lung to radon in the nature. The risk of lung cancer was estimated to increase by 8 to 13% per every 100 Bq m-3 concentration of radon in the air. We observed beta rays with maximum energy of 3.27 MeV emitted from 214Bi as one of the progenies based on a detection of Cherenkov radiation. The surface radioactivity concentration of 214Bi on the sample was measured; the relation between the concentration and exposure time for the sample at the room air is researched. The behavior of the radon progenies in the air is discussed by a research for the progenies attaching on the sample after the radon decay. The inhalation of the radon progenies is not clear. Thus, to understand the behavior of progenies in the air make to clear the causal relation between the radon concentration and lung cancers
Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation
A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm-2) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm-2). When SHI irradiation of oxygen ions of fluence 1 × 1013 ions/cm2 was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs
In vitro phosphorylation as tool for modification of silk and keratin fibrous materials
An overview is given of the recent work on in vitro enzymatic phosphorylation of silk fibroin and human hair keratin. Opposing to many chemical "conventional" approaches, enzymatic phosphorylation is in fact a mild reaction and the treatment falls within "green chemistry" approach. Silk and keratin are not phosphorylated in vivo, but in vitro. This enzyme-driven modification is a major technological breakthrough. Harsh chemical chemicals are avoided, and mild conditions make enzymatic phosphorylation a real "green chemistry" approach. The current communication presents a novel approach stating that enzyme phosphorylation may be used as a tool to modify the surface charge of biocompatible materials such as keratin and silk
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