1,188 research outputs found

    The properties of the three-nucleon system with the dressed-bag model for nn interaction. I: New scalar three-body force

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    A multi-component formalism is developed to describe three-body systems with nonstatic pairwise interactions and non-nucleonic degrees of freedom. The dressed-bag model for NNNN interaction based on the formation of an intermediate six-quark bag dressed by a σ\sigma-field is applied to the 3N3N system, where it results in a new three-body force between the six-quark bag and a third nucleon. Concise variational calculations of 3N3N bound states are carried out in the dressed-bag model including the new three-body force. It is shown that this three-body force gives at least half the 3N3N total binding energy, while the weight of non-nucleonic components in the 3^3H and 3^3He wavefunctions can exceed 10%. The new force model provides a very good description of 3N3N bound states with a reasonable magnitude of the σNN\sigma NN coupling constant. The model can serve as a natural bridge between dynamical description of few-nucleon systems and the very successful Walecka approach to heavy nuclei and nuclear matter.Comment: 26 pages, Latex, 7 figure

    Transplacental Transmission of Leishmania infantum as a Means for Continued Disease Incidence in North America

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    Dogs are a favored feeding source for sand flies that transmit human L. infantum infection. Zoonotic visceral leishmaniasis (ZVL) is an emerging problem in some U.S. dog breeds, with over 20% of at-risk Foxhounds infected. Although classically Leishmania is transmitted by infected sand flies which exist in the United States, no role has yet been determined for vector-borne transmission. Means of ongoing L. infantum transmission in U.S. dogs is unknown. Possibilities include transplacental and horizontal/venereal transmission. Aims for this study were to establish whether transplacental transmission occurred in Leishmania-infected U.S. dogs and determine the effect of this transmission on immune recognition of Leishmania. This novel report describes wide-spread infection as identified by kqPCR in 8 day-old pups born to a naturally-infected, seropositive U.S. dog with no travel history. This is the first report of transplacental transmission of L. infantum in naturally-infected dogs in North America. Evidence that mom-to-pup transmission of ZVL may continue disease in an otherwise non-endemic region has significant implications on current control strategies for ZVL. Determining frequency of vertical transmission and incorporating canine sterilization with vector control may have a more significant impact on ZVL transmission to people in endemic areas than current control efforts

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Search for pair-produced long-lived neutral particles decaying to jets in the ATLAS hadronic calorimeter in ppcollisions at √s=8TeV

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    The ATLAS detector at the Large Hadron Collider at CERN is used to search for the decay of a scalar boson to a pair of long-lived particles, neutral under the Standard Model gauge group, in 20.3fb−1of data collected in proton–proton collisions at √s=8TeV. This search is sensitive to long-lived particles that decay to Standard Model particles producing jets at the outer edge of the ATLAS electromagnetic calorimeter or inside the hadronic calorimeter. No significant excess of events is observed. Limits are reported on the product of the scalar boson production cross section times branching ratio into long-lived neutral particles as a function of the proper lifetime of the particles. Limits are reported for boson masses from 100 GeVto 900 GeV, and a long-lived neutral particle mass from 10 GeVto 150 GeV

    Effect of Fructooligosaccharide Metabolism on Chicken Colonization by an Extra-Intestinal Pathogenic Escherichia coli Strain

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    Extra-intestinal pathogenic Escherichia coli (ExPEC) strains cause many diseases in humans and animals. While remaining asymptomatic, they can colonize the intestine for subsequent extra-intestinal infection and dissemination in the environment. We have previously identified the fos locus, a gene cluster within a pathogenicity island of the avian ExPEC strain BEN2908, involved in the metabolism of short-chain fructooligosaccharides (scFOS). It is assumed that these sugars are metabolized by the probiotic bacteria of the microbiota present in the intestine, leading to a decrease in the pathogenic bacterial population. However, we have previously shown that scFOS metabolism helps BEN2908 to colonize the intestine, its reservoir. As the fos locus is located on a pathogenicity island, one aim of this study was to investigate a possible role of this locus in the virulence of the strain for chicken. We thus analysed fos gene expression in extracts of target organs of avian colibacillosis and performed a virulence assay in chickens. Moreover, in order to understand the involvement of the fos locus in intestinal colonization, we monitored the expression of fos genes and their implication in the growth ability of the strain in intestinal extracts of chicken. We also performed intestinal colonization assays in axenic and Specific Pathogen-Free (SPF) chickens. We demonstrated that the fos locus is not involved in the virulence of BEN2908 for chickens and is strongly involved in axenic chicken cecal colonization both in vitro and in vivo. However, even if the presence of a microbiota does not inhibit the growth advantage of BEN2908 in ceca in vitro, overall, growth of the strain is not favoured in the ceca of SPF chickens. These findings indicate that scFOS metabolism by an ExPEC strain can contribute to its fitness in ceca but this benefit is fully dependent on the bacteria present in the microbiota

    A Genome-Wide Association Study of Nephrolithiasis in the Japanese Population Identifies Novel Susceptible Loci at 5q35.3, 7p14.3, and 13q14.1

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    Nephrolithiasis is a common nephrologic disorder with complex etiology. To identify the genetic factor(s) for nephrolithiasis, we conducted a three-stage genome-wide association study (GWAS) using a total of 5,892 nephrolithiasis cases and 17,809 controls of Japanese origin. Here we found three novel loci for nephrolithiasis: RGS14-SLC34A1-PFN3-F12 on 5q35.3 (rs11746443; P = 8.51×10−12, odds ratio (OR) = 1.19), INMT-FAM188B-AQP1 on 7p14.3 (rs1000597; P = 2.16×10−14, OR = 1.22), and DGKH on 13q14.1 (rs4142110; P = 4.62×10−9, OR = 1.14). Subsequent analyses in 21,842 Japanese subjects revealed the association of SNP rs11746443 with the reduction of estimated glomerular filtration rate (eGFR) (P = 6.54×10−8), suggesting a crucial role for this variation in renal function. Our findings elucidated the significance of genetic variations for the pathogenesis of nephrolithiasis

    Association study of genetic variants of pro-inflammatory chemokine and cytokine genes in systemic lupus erythematosus

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    BACKGROUND: Several lines of evidence suggest that chemokines and cytokines play an important role in the inflammatory development and progression of systemic lupus erythematosus. The aim of this study was to evaluate the relevance of functional genetic variations of RANTES, IL-8, IL-1α, and MCP-1 for systemic lupus erythematosus. METHODS: The study was conducted on 500 SLE patients and 481 ethnically matched healthy controls. Genotyping of polymorphisms in the RANTES, IL-8, IL-1α, and MCP-1 genes were performed using a real-time polymerase chain reaction (PCR) system with pre-developed TaqMan allelic discrimination assay. RESULTS: No significant differences between SLE patients and healthy controls were observed when comparing genotype, allele or haplotype frequencies of the RANTES, IL-8, IL-1α, and MCP-1 polymorphisms. In addition, no evidence for association with clinical sub-features of SLE was found. CONCLUSION: These results suggest that the tested functional variation of RANTES, IL-8, IL-1α, and MCP-1 genes do not confer a relevant role in the susceptibility or severity of SLE in the Spanish population

    Modeling of negative Poisson’s ratio (auxetic) crystalline cellulose Iβ

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    Energy minimizations for unstretched and stretched cellulose models using an all-atom empirical force field (Molecular Mechanics) have been performed to investigate the mechanism for auxetic (negative Poisson’s ratio) response in crystalline cellulose Iβ from kraft cooked Norway spruce. An initial investigation to identify an appropriate force field led to a study of the structure and elastic constants from models employing the CVFF force field. Negative values of on-axis Poisson’s ratios nu31 and nu13 in the x1-x3 plane containing the chain direction (x3) were realized in energy minimizations employing a stress perpendicular to the hydrogen-bonded cellobiose sheets to simulate swelling in this direction due to the kraft cooking process. Energy minimizations of structural evolution due to stretching along the x3 chain direction of the ‘swollen’ (kraft cooked) model identified chain rotation about the chain axis combined with inextensible secondary bonds as the most likely mechanism for auxetic response

    Dibaryon model for nuclear force and the properties of the 3N3N system

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    The dibaryon model for NNNN interaction, which implies the formation of an intermediate six-quark bag dressed by a σ\sigma-field, is applied to the 3N3N system, where it results in a new three-body force of scalar nature between the six-quark bag and a third nucleon. A new multicomponent formalism is developed to describe three-body systems with nonstatic pairwise interactions and non-nucleonic degrees of freedom. Precise variational calculations of 3N3N bound states are carried out in the dressed-bag model including the new scalar three-body force. The unified coupling constants and form factors for 2N2N and 3N3N force operators are used in the present approach, in a sharp contrast to conventional meson-exchange models. It is shown that this three-body force gives at least half the 3N3N total binding energy, while the weight of non-nucleonic components in the 3^3H and 3^3He wavefunctions can exceed 10%. The new force model provides a very good description of 3N3N bound states with a reasonable magnitude of the σNN\sigma NN coupling constant. A new Coulomb 3N3N force between the third nucleon and dibaryon is found to be very important for a correct description of the Coulomb energy and r.m.s. charge radius in 3^3He. In view of the new results for Coulomb displacement energy obtained here for A=3 nuclei, an explanation for the long-term Nolen--Schiffer paradox in nuclear physics is suggested. The role of the charge-symmetry-breaking effects in the nuclear force is discussed.Comment: 64 pages, 7 figures, LaTeX, to be published in Phys. At. Nucl. (2005
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