16,490 research outputs found

    Identification of the long polar fimbriae gene variants in the locus of enterocyte effacement-negative Shiga toxin-producing Escherichia coli strains isolated from humans and cattle in Argentina

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    The long polar fimbriae (Lpf) is one of few adhesive factors of Shiga toxin-producing Escherichia coli (STEC) and it is associated with colonization of the intestine. Studies have demonstrated the presence of lpf genes in several pathogenic E. coli strains, and classification of variants based on polymorphisms in the lpfA1 and lpfA2 genes has been adopted. Using a collection of Argentinean locus of enterocyte effacement (LEE)-negative STEC strains, we determined that the different lpfA types were present in a wide variety of serotypes with no apparent association between the types of lpfA1 or lpfA2 genes and the severity of human disease. The lpfA2-1 was the most prevalent variant identified, which was present in 95.8% of the isolates, and lpfA1-3 and lpfA2-2, proposed as specific biomarkers of E. coli O157:H7, were not found in any of the serotypes studied. The prevalence of lpf genes in a large number of strains is useful to understand the genetic diversity of LEE-negative STEC and to define the association of some of these isolates carrying specific lpf-variants with disease.Fil: Galli, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Torres, Alfredo G.. University of Texas Medical Branch; Estados UnidosFil: Rivas, Marta. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentin

    Inequality of Outcomes and Inequality of Opportunities in Brazil

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    This paper departs from John Roemer's theory of equality of opportunities. We seek to determine what part of observed outcome inequality may be attributed to differences in observed 'circumstances', including family background, and what part is due to 'personal efforts'. We use a micro-econometric technique to simulate what the distribution of outcomes would look like if 'circumstances' were the same for everybody. This technique is applied to Brazilian data from the 1996 household survey, both for earnings and for household incomes. It is shown that observed circumstances are a major source of outcome inequality in Brazil, probably more so than in other countries for which information is available. Nevertheless, the level of inequality after observed circumstances are equalized remains very high in Brazil.http://deepblue.lib.umich.edu/bitstream/2027.42/40016/3/wp630.pd

    Ethnic polarization and the duration of civil wars

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    The authors analyze the relationship between ethnic polarization and the duration of civil wars. Several recent papers have argued that the uncertainty about the relative power of the contenders in a war will tend to increase its duration. In these models, uncertainty is directly related to the relative size of the contenders. The authors argue that the duration of civil wars increases the more polarized a society is. Uncertainty is not necessarily linked to the structure of the population but it could be traced back to the measurement of the size of the different groups in the society. Given a specific level of measurement error or uncertainty, more polarization implies lengthier wars. The empirical results show that ethnically polarized countries have to endure longer civil wars than ethnically less polarized societies.Social Conflict and Violence,Population Policies,Peace&Peacekeeping,Post Conflict Reintegration,Services&Transfers to Poor

    Cosmology with intensity mapping techniques using atomic and molecular lines

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    We present a systematic study of the intensity mapping technique using updated models for the different emission lines from galaxies and identify which ones are more promising for cosmological studies of the post reionization epoch. We consider the emission of Lyα{\rm Ly\alpha}, Hα{\rm H\alpha}, Hβ\beta, optical and infrared oxygen lines, nitrogen lines, CII and the CO rotational lines. We then identify that Lyα{\rm Ly\alpha}, Hα{\rm H\alpha}, OII, CII and the lowest rotational CO lines are the best candidates to be used as IM probes. These lines form a complementary set of probes of the galaxies emission spectra. We then use reasonable experimental setups from current, planned or proposed experiments to access the detectability of the power spectrum of each emission line. Intensity mapping of Lyα{\rm Ly\alpha} emission from z=2z=2 to 3 will be possible in the near future with HETDEX, while far-infrared lines require new dedicated experiments. We also show that the proposed SPHEREx satellite can use OII and Hα{\rm H\alpha} IM to study the large-scale distribution of matter in intermediate redshifts of 1 to 4. We found that submilimeter experiments with bolometers can have similar performances at intermediate redshifts using CII and CO(3-2).Comment: 18 pages, 21 figures, 5 tables, published in MNRAS, typos correcte

    Inequality of outcomes and inequality of opportunities in Brazil

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    This paper departs from John Roemer's formulation of the theory of equality of opportunities. It seeks to determine what part of observed outcome inequality may be attributed to differences in observed 'circumstances', including family background, and what part is due to 'personal efforts'. We use a micro-econometric technique to simulate what the distribution of outcomes would look like if 'circumstances' were the same for everybody. This technique is applied to Brazilian data from the 1996 household survey, both on the distribution of earnings for active individuals and on the distribution of household income per capita. It is shown that observed circumstances are a major source of outcome inequality in Brazil, probably more so than in other countries for which information is available. Yet, the level of inequality after equalizing circumstances remains very high. While a policy aimed at equalizing opportunities - through facilitating more equal access to schooling, for instance - might therefore be successful in lowering Brazilian inequality somewhat, more ambitious targets for inequality reduction may require more direct income redistribution.Inequality of Opportunities, Intergenerational Educational Mobility JEL Codes: D31, D63, J62

    Self-force as a cosmic censor in the Kerr overspinning problem

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    It is known that a near-extremal Kerr black hole can be spun up beyond its extremal limit by capturing a test particle. Here we show that overspinning is always averted once back-reaction from the particle's own gravity is properly taken into account. We focus on nonspinning, uncharged, massive particles thrown in along the equatorial plane, and work in the first-order self-force approximation (i.e., we include all relevant corrections to the particle's acceleration through linear order in the ratio, assumed small, between the particle's energy and the black hole's mass). Our calculation is a numerical implementation of a recent analysis by two of us [Phys.\ Rev.\ D {\bf 91}, 104024 (2015)], in which a necessary and sufficient "censorship" condition was formulated for the capture scenario, involving certain self-force quantities calculated on the one-parameter family of unstable circular geodesics in the extremal limit. The self-force information accounts both for radiative losses and for the finite-mass correction to the critical value of the impact parameter. Here we obtain the required self-force data, and present strong evidence to suggest that captured particles never drive the black hole beyond its extremal limit. We show, however, that, within our first-order self-force approximation, it is possible to reach the extremal limit with a suitable choice of initial orbital parameters. To rule out such a possibility would require (currently unavailable) information about higher-order self-force corrections.Comment: 13 pages, 3 figure

    Rare diseases of the anterior segment of the eye: update on diagnosis and management

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    This special issue is focused on the current approaches used to identify and manage rare diseases of the anterior segment of the eye, which range from congenital to acquired disorders that are caused by ocular or systemic conditions and often have consequences that extend beyond the anterior segment of the eye

    A system of mobile agents to model social networks

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    We propose a model of mobile agents to construct social networks, based on a system of moving particles by keeping track of the collisions during their permanence in the system. We reproduce not only the degree distribution, clustering coefficient and shortest path length of a large data base of empirical friendship networks recently collected, but also some features related with their community structure. The model is completely characterized by the collision rate and above a critical collision rate we find the emergence of a giant cluster in the universality class of two-dimensional percolation. Moreover, we propose possible schemes to reproduce other networks of particular social contacts, namely sexual contacts.Comment: Phys. Rev. Lett. (in press
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