959 research outputs found

    Do Quarks Obey D-Brane Dynamics?

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    The potential between two D0-branes at rest is calculated to be a linear. Also the potential between two fast decaying D0-branes is found in agreement with phenomenological heavy-quark potentials.Comment: 7 pages, no figures, LaTe

    BF models, Duality and Bosonization on higher genus surfaces

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    The generating functional of two dimensional BFBF field theories coupled to fermionic fields and conserved currents is computed in the general case when the base manifold is a genus g compact Riemann surface. The lagrangian density L=dBAL=dB{\wedge}A is written in terms of a globally defined 1-form AA and a multi-valued scalar field BB. Consistency conditions on the periods of dBdB have to be imposed. It is shown that there exist a non-trivial dependence of the generating functional on the topological restrictions imposed to BB. In particular if the periods of the BB field are constrained to take values 4πn4\pi n, with nn any integer, then the partition function is independent of the chosen spin structure and may be written as a sum over all the spin structures associated to the fermions even when one started with a fixed spin structure. These results are then applied to the functional bosonization of fermionic fields on higher genus surfaces. A bosonized form of the partition function which takes care of the chosen spin structure is obtainedComment: 17 page

    Egalitarian despots: hierarchy steepness, reciprocity and the grooming-trade model in wild chimpanzees (Pan troglodytes)

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    Biological-markets theory models the action of natural selection as a marketplace in which animals are viewed as traders with commodities to offer and exchange. Studies of female Old World monkeys have suggested that grooming might be employed as a commodity to be reciprocated or traded for alternative services, yet previous tests of this grooming-trade model in wild adult male chimpanzees (Pan troglodytes) have yielded mixed results. Here we provide the strongest test of the model to date for male chimpanzees: we use data drawn from two social groups (communities) of chimpanzees from different populations, and give explicit consideration to variation in dominance hierarchy steepness as such variation results in differing conditions for biological markets. First, analysis of data from published accounts of other chimpanzee communities, together with our own data, showed that hierarchy steepness varied considerably within and across communities and that the number of adult males in a community aged 20-30 years predicted hierarchy steepness. The two communities in which we tested predictions of the grooming-trade model lay at opposite extremes of this distribution. Second, in accord with the grooming-trade model, we found evidence that male chimpanzees trade grooming for agonistic support where hierarchies are steep (despotic) and consequent effective support is a rank-related commodity, but not where hierarchies are shallow (egalitarian). However, we also found that grooming was reciprocated regardless of hierarchy steepness. Our findings also hint at the possibility of agonistic competition, or at least exclusion, in relation to grooming opportunities compromising the free market envisioned by Biological Markets theory. Our results build on previous findings across chimpanzee communities to emphasise the importance of reciprocal grooming exchanges among adult male chimpanzees, which can be understood in a biological markets framework if grooming by or with particular individuals is a valuable commodity

    Mineral chemistry of igneous melanite garnets from analcite-bearing volcanic rocks, Alberta, Canada

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    The mineral chemistry of melanite garnets from the Crowsnest volcanic rocks of SW Alberta, Canada, has been investigated by using electron microprobe scans, quantitative analyses and multivariate statistical analysis. The garnets occur with aegirine-augite, sanidine, analcite and rare plagioclase as phenocrysts in trachyte and phonolite flows, agglomerates and tuffs. Wavelength dispersive microprobe scans reveal complex zonation patterns, both normal and oscillatory. The results of fifty quantitative analyses were subjected to R-mode factor analysis to delineate the chemical exchanges producing the zonation. The chemical zonation of the garnets may be attributed to four independent binary exchanges; Al-Fe3+, Si-Ti, Ca-Mn and Mg-Fe2+. The stoichiometry of these garnets, based on microprobe and wet chemical Fe analyses, combined with the strongly antithetic behavior of Si and Ti lead us to infer that the Ti in these garnets is dominantly tetravalent. It is clear from this study that quantitative modelling of the processes of crystal growth and zonation of melanite garnets in alkaline, undersaturated igneous rocks should be aimed at simulating the four chemical exchanges listed above

    Discovery of Markers of Exposure Specific to Bites of Lutzomyia longipalpis, the Vector of Leishmania infantum chagasi in Latin America

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    Leishmania parasites are transmitted by the bite of an infected vector sand fly that injects salivary molecules into the host skin during feeding. Certain salivary molecules can produce antibodies and can be used as an indicator of exposure to a vector sand fly and potentially the disease it transmits. Here we identified potential markers of specific exposure to the sand fly Lutzomyia longipalpis, the vector of visceral leishmaniasis in Latin America. Initially, we determined which of the salivary proteins produce antibodies in humans, dogs, and foxes from areas endemic for the disease. To identify potential specific markers of vector exposure, we produced nine different recombinant salivary proteins from Lu. longipalpis and tested for their recognition by individuals exposed to another human-biting sand fly, Lu. intermedia, that transmits cutaneous leishmaniasis and commonly occurs in the same endemic areas as Lu. longipalpis. Two of the nine salivary proteins were recognized only by humans exposed to Lu. longipalpis, suggesting they are immunogenic proteins and may be useful in epidemiological studies. The identification of specific salivary proteins as potential markers of exposure to vector sand flies will increase our understanding of vector–human interaction, bring new insights to vector control, and in some instances act as an indicator for risk of acquiring disease

    Jet Substructure at the Tevatron and LHC: New results, new tools, new benchmarks

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    In this report we review recent theoretical progress and the latest experimental results in jet substructure from the Tevatron and the LHC. We review the status of and outlook for calculation and simulation tools for studying jet substructure. Following up on the report of the Boost 2010 workshop, we present a new set of benchmark comparisons of substructure techniques, focusing on the set of variables and grooming methods that are collectively known as "top taggers". To facilitate further exploration, we have attempted to collect, harmonise, and publish software implementations of these techniques.Comment: 53 pages, 17 figures. L. Asquith, S. Rappoccio, C. K. Vermilion, editors; v2: minor edits from journal revision

    The Efficacy of Oncolytic Viruses in Reducing Neoplasms: A Scoping Review

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    Pancreatic cancer is one of the cancers with the highest mortality rate, largely due to the aggressiveness of the tumor cells and the lack of obvious symptoms at the beginning of the disease. Based on this, the present review aims to analyze the effectiveness of using oncolytic viruses in the treatment of pancreatic neoplasms. To this end, using the PCC research strategy, an acronym for eligibility criteria that means Population, Concept, and Context, the scientific databases PubMed/MEDLINE, LILACS, EMBASE, and ScienceDirect were used. After applying the processes of inclusion, exclusion, selection, data extraction, and assessment of the Level of Evidence, the results were six articles analyzed and used for the scoping review. At the end of the analysis of these articles, two of them detected the DNA of the viruses in the patients' blood, two presented grade I-II adverse events, and two used the same virus. Thus, five of the six articles analyzed demonstrated positive results, with the sixth being considered inconclusive. Therefore, it can be concluded that the treatment of pancreatic neoplasms with the use of oncolytic viruses, depending on the virus and the doses used, presents positive prospects for regression or interruption of the worsening of the disease, proving to be a source of hope for the future. Pancreatic cancer is one of the cancers with the highest mortality rate, largely due to the aggressiveness of the tumor cells and the lack of obvious symptoms at the beginning of the disease. Based on this, the present review aims to analyze the effectiveness of using oncolytic viruses in the treatment of pancreatic neoplasms. To this end, using the PCC research strategy, an acronym for eligibility criteria that means Population, Concept, and Context, the scientific databases PubMed/MEDLINE, LILACS, EMBASE, and ScienceDirect were used. After applying the processes of inclusion, exclusion, selection, data extraction, and assessment of the Level of Evidence, the results were six articles analyzed and used for the scoping review. At the end of the analysis of these articles, two of them detected the DNA of the viruses in the patients' blood, two presented grade I-II adverse events, and two used the same virus. Thus, five of the six articles analyzed demonstrated positive results, with the sixth being considered inconclusive. Therefore, it can be concluded that the treatment of pancreatic neoplasms with the use of oncolytic viruses, depending on the virus and the doses used, presents positive prospects for regression or interruption of the worsening of the disease, proving to be a source of hope for the future.

    Histomorphometric analysis of inflammatory response and necrosis in re-implanted central incisor of rats treated with low-level laser therapy

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    Low-level laser therapy is a tool employed in the management of post-operative inflammation process and in the enhancement of reparative process. The aim of the study was to perform histological evaluation of dental and periodontal ligament of rats central upper-left incisor teeth re-implanted and irradiated with low-level laser (InGaAl, 685 nm, 50 J/cm2) 15, 30, and 60 days after re-implantation. Seventy-two male rats had the central upper left incisor removed and kept for 15 min on dry gauze before replantation. Laser was irradiated over the root surface and empty alveolus prior replantation and over surrounding mucosa after the re-implantation. After histological procedures, all slices were analyzed regarding external resorption area and histological aspects. We observed an increase of root resorption (p < 0.05) in the control group compared to the laser group at 15, 30, and 60 days. These results showed that the laser groups developed less root resorption areas than the control group in all experimental periods. Additionally, histological analysis revealed less inflammatory cells and necrotic areas in laser groups
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