Mass singularity and confining property in QED3QED_3

We discuss the properties of the position space fermion propagator in three dimensional QED which has been found previouly based on Ward-Takahashi-identity for soft-photon emission vertex and spectral representation.There is a new type of mass singularity which governs the long distance behaviour.It leads the propagator vanish at large distance.This term corresponds to dynamical mass in position space.Our model shows confining property and dynamical mass generation for arbitrary coupling constant.Since we used dispersion retation in deriving spectral function there is a physical mass which sets a mass scale.For finite cut off we obtain the full propagator in the dispersion integral as a superposition of different massses.Low energy behaviour of the proagator is modified to decrease by position dependent mass.In the limit of zero infrared cut-off the propagator vanishes with a new kind of infrared behaviour.Comment: 22pages,4figures,revtex4,Notational sloppiness are crrected.Submitted to JHE

Absolute elastic differential cross sections for electron scattering by C6 H5 CH3 and C6 H5 CF3 at 1.5-200 eV: A comparative experimental and theoretical study with C6 H6

We present absolute differential cross sections (DCS) for elastic scattering from two benzene derivatives C6 H5 CH3 and C6 H5 CF3. The crossed-beam method was used in conjunction with the relative flow technique using helium as the reference gas to obtain absolute values. Measurements were carried out for scattering angles 15°-130° and impact energies 1.5-200 eV. DCS results for these two molecules were compared to those of C6 H6 from our previous study. We found that (1) these three molecules have DCS with very similar magnitudes and shapes over the energy range 1.5-200 eV, although DCS for C6 H5 CF3 increase steeply toward lower scattering angles due to the dipole moment induced long-range interaction at 1.5 and 4.5 eV, and (2) that the molecular structure of the benzene ring significantly determines the collision dynamics. From the measured DCS, elastic integral cross sections have been calculated. Furthermore, by employing a corrected form of the independent-atom method known as the screen corrected additive rule, DCS calculations have been carried out without any empirical parameter fittings, i.e., in an ab initio nature. Results show that the calculated DCS are in excellent agreement with the experimental values at 50, 100, and 200 eV. © 2009 The American Physical Society.F.B. and G.G. were also supported by the Spanish Ministerio de Ciencia e Innovación Project No. FIS0032-00702 and the European Science Foundation EIPAM network and COST Action CM0601.Peer Reviewe

Divergent northern and southern populations and demographic history of the pearl oyster in the western Pacific revealed with genomic SNPs

In the open ocean without terrain boundaries, marine invertebrates with pelagic larvae can migrate long distances using ocean currents, suggesting reduced genetic diversification. Contrary to this assumption, however, genetic differentiation is often observed in marine invertebrates. In the present study, we sought to explain how population structure is established in the western Pacific Ocean, where the strong Kuroshio Current maintains high levels of gene flow from south to north, presumably promoting genetic homogeneity. We determined the population structure of the pearl oyster, Pinctada fucata, in the Indo-Pacific Ocean using genome-wide genotyping data from multiple sampling localities. Cluster analysis showed that the western Pacific population is distinct from that of the Indian Ocean, and that it is divided into northern (Japanese mainland) and southern (Nansei Islands, China, and Cambodia) populations. Genetic differentiation of P. fucata can be explained by geographic barriers in the Indian Ocean and a local lagoon, and by environmental gradients of sea surface temperature (SST) and oxygen concentration in the western Pacific. A genome scan showed evidence of adaptive evolution in genomic loci, possibly associated with changes in environmental factors, including SST and oxygen concentration. Furthermore, Bayesian simulation demonstrated that the past population expansion and division are congruent with ocean warming after the last glacial period. It is highly likely that the environmental gradient forms a genetic barrier that diversifies P. fucata populations in the western Pacific. This hypothesis helps to explain genetic differentiation and possible speciation of marine invertebrates

Monte Carlo study of Si(111) homoepitaxy

An attempt is made to simulate the homoepitaxial growth of a Si(111) surface by the kinetic Monte Carlo method in which the standard Solid-on-Solid model and the planar model of the (7x7) surface reconstruction are used in combination. By taking account of surface reconstructions as well as atomic deposition and migrations, it is shown that the effect of a coorparative stacking transformation is necessary for a layer growth.Comment: 4 pages, 5 figures. For Fig.1 of this article, please see Fig.2 of Phys.Rev. B56, 3583 (1997). To appear in Phys.Rev.B. (June 1998

Overexpression of Chitinase 3-Like 1/YKL-40 in Lung-Specific IL-18-Transgenic Mice, Smokers and COPD

We analyzed the lung mRNA expression profiles of a murine model of COPD developed using a lung-specific IL-18-transgenic mouse. In this transgenic mouse, the expression of 608 genes was found to vary more than 2-fold in comparison with control WT mice, and was clustered into 4 groups. The expression of 140 genes was constitutively increased at all ages, 215 genes increased gradually with aging, 171 genes decreased gradually with aging, and 82 genes decreased temporarily at 9 weeks of age. Interestingly, the levels of mRNA for the chitinase-related genes chitinase 3-like 1 (Chi3l1), Chi3l3, and acidic mammalian chitinase (AMCase) were significantly higher in the lungs of transgenic mice than in control mice. The level of Chi3l1 protein increased significantly with aging in the lungs and sera of IL-18 transgenic, but not WT mice. Previous studies have suggested Chi3l3 and AMCase are IL-13-driven chitinase-like proteins. However, IL-13 gene deletion did not reduce the level of Chi3l1 protein in the lungs of IL-18 transgenic mice. Based on our murine model gene expression data, we analyzed the protein level of YKL-40, the human homolog of Chi3l1, in sera of smokers and COPD patients. Sixteen COPD patients had undergone high resolution computed tomography (HRCT) examination. Emphysema was assessed by using a density mask with a cutoff of −950 Hounsfield units to calculate the low-attenuation area percentage (LAA%). We observed significantly higher serum levels in samples from 28 smokers and 45 COPD patients compared to 30 non-smokers. In COPD patients, there was a significant negative correlation between serum level of YKL-40 and %FEV1. Moreover, there was a significant positive correlation between the serum levels of YKL-40 and LAA% in COPD patients. Thus our results suggest that chitinase-related genes may play an important role in establishing pulmonary inflammation and emphysematous changes in smokers and COPD patients

Dynamical mass generation of a two-component fermion in Maxwell-Chern-Simons QED_3: The lowest ladder approximation

Dynamical mass generation of a two-component fermion in $QED_3$ with a Chern-Simons term is investigated by solving the Schwinger-Dyson equation formulated in the lowest ladder approximation. Dependence of the dynamical fermion mass on a gauge-fixing parameter, a gauge coupling constant, and a topological mass is examined by approximated analytical and also numerical methods. The inclusion of the Chern-Simons term makes impossible to choose a peculiar gauge in which a wave function renormalization is absent. The numerical evaluation shows that the wave function renormalization is fairly close to 1 in the Landau gauge. It means that this gauge is still a specific gauge where the Ward-Takahashi identity is satisfied approximately. We also find that the dynamical mass is almost constant if the topological mass is larger than the coupling constant, while it decreases when the topological mass is comparable to or smaller than the coupling constant and tends to the value in $QED_3$ without the Chern-Simons term.Comment: 22 pages, 9 figures, Version to appear in Phys. Rev.

Optical properties of quantum wires: Disorder-scattering in the Lloyd-model

The Lloyd model is extended to the exciton problem in quasi one-dimensional structures to study the interplay between the Coulomb attraction and disorder scattering. Within this model the averaging and resummation of the locator series can be performed analytically. As an application, the optical absorption in quantum box wires is investigated. Without electron-hole interaction, fluctuations in the well-width lead to an asymmetric broadening of the minibands with respect to the lower and upper band-edges.Comment: 7 pages, 6 figure

A first measurement of the interaction cross section of the tau neutrino

The DONuT experiment collected data in 1997 and published first results in 2000 based on four observed $\nu_\tau$ charged-current (CC) interactions. The final analysis of the data collected in the experiment is presented in this paper, based on $3.6 \times 10^{17}$ protons on target using the 800 GeV Tevatron beam at Fermilab. The number of observed $\nu_\tau$ CC interactions is 9, from a total of 578 observed neutrino interactions. We calculated the energy-independent part of the tau-neutrino CC cross section ($\nu + \bar \nu$), relative to the well-known $\nu_e$ and $\nu_\mu$ cross sections. The ratio $\sigma(\nu_\tau)$/$\sigma(\nu_{e,\mu})$ was found to be $1.37\pm0.35\pm0.77$. The $\nu_\tau$ CC cross section was found to be $0.72 \pm 0.24\pm0.36 \times 10^{-38}$ cm$^{2}\rm{GeV}^{-1}$. Both results are in agreement the Standard Model.Comment: 37 pages, 15 figure

Injúria de Spodoptera frugiperda em milho Bt em sucessão a soja transgênica e submetido a diferentes manejos fitossanitários.

A sucessão soja-milho e o uso de plantas geneticamente modificadas (GM), resistentes a lagartas (Bt) e glifosato (RR), se tornou comum entre os agricultores nos últimos anos. O objetivo do trabalho foi avaliar a injúria causada por Spodoptera frugiperda em milho Bt (Cry1Ab) em sucessão a soja transgênica e submetido a diferentes manejos fitossanitários. Foi utilizado o delineamento em blocos ao acaso, com quatro repetições e parcelas de 18x18m. Os tratamentos consistiram em diferentes combinações de plantas transgênicas, na sucessão soja-milho: (T1) soja não-GM e milho não-Bt; (T2) soja não-GM e milhoBt; (T3) sojaRR e milho não-Bt; (T4) sojaRR e milhoBt; (T5) sojaBtRR e milho não-Bt; (T6) sojaBtRR e milho Bt; (T7) sojaRR e milhoBt com aplicação de inseticidas junto com herbicida e fungicida, totalizando 5 aplicações em soja e 3 em milho. De T1 a T6 os inseticidas foram aplicados de acordo com o nível de controle. As injúrias de S. frugiperda foram avaliadas nos estágios V4, V6 e V8 do milho, em 5 pontos por parcela, cada um com 10 plantas. Para a avaliação foi usada uma escala de notas (0-6) e a classificação das plantas em integras, injúria leve, injúria moderada e injúria intensa. Os dados foram submetidos ao teste de Kruskal-Wallis e comparados por Student-Newman-Keuls. Para ambos parâmetros, os tratamentos com milho Bt não diferiram entre si, mas diferiram dos com milho não-Bt. As taxas de plantas íntegras foram maiores no milho Bt (V4=81%; V6=94%; V8=99%) em relação ao milho não-Bt (V4=5%; V6=26%; V8=66%). As notas de injúria foram menores no milho Bt (V4=0,3; V6=0,1; V8=0,03) em relação ao milho não-Bt (V4=3,6; V6=2,3; V8=1,1). Assim, o milho Bt reduziu a intensidade de ataque da praga e as plantas ficaram mais tolerantes com o passar do tempo. Não há evidências do efeito do genótipo de soja (Bt, RR ou não-GM), cultivado anteriormente, e do manejo fitossanitário sobre a intensidade de ataque de S. frugiperda em milho