Nonlocal annihilation of Weyl fermions in correlated systems

Weyl semimetals (WSMs) are characterized by topologically stable pairs of nodal points in the band structure that typically originate from splitting a degenerate Dirac point by breaking symmetries such as time-reversal or inversion symmetry. Within the independent-electron approximation, the transition between an insulating state and a WSM requires the local creation or annihilation of one or several pairs of Weyl nodes in reciprocal space. Here, we show that strong electron-electron interactions may qualitatively change this scenario. In particular, we reveal that the transition to a Weyl semimetallic phase can become discontinuous, and, quite remarkably, pairs of Weyl nodes with a finite distance in momentum space suddenly appear or disappear in the spectral function. We associate this behavior with the buildup of strong many-body correlations in the topologically nontrivial regions, manifesting in dynamical fluctuations in the orbital channel. We also highlight the impact of electronic correlations on the Fermi arcs

Castração de leitões: avaliação entre os métodos inguinal e escrotal.

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Valores de digestibilidade e composição química e bromatológica de alguns alimentos para suínos.

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Tamanho da partícula afeta a digestibilidade do farelo de girassol em suínos.

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Association between Outdoor Air Pollution and Childhood Leukemia: A Systematic Review and Dose-Response Meta-Analysis.

BackgroundA causal link between outdoor air pollution and childhood leukemia has been proposed, but some older studies suffer from methodological drawbacks. To the best of our knowledge, no systematic reviews have summarized the most recently published evidence and no analyses have examined the dose-response relation.ObjectiveWe investigated the extent to which outdoor air pollution, especially as resulting from traffic-related contaminants, affects the risk of childhood leukemia.MethodsWe searched all case-control and cohort studies that have investigated the risk of childhood leukemia in relation to exposure either to motorized traffic and related contaminants, based on various traffic-related metrics (number of vehicles in the closest roads, road density, and distance from major roads), or to measured or modeled levels of air contaminants such as benzene, nitrogen dioxide, 1,3-butadiene, and particulate matter. We carried out a meta-analysis of all eligible studies, including nine studies published since the last systematic review and, when possible, we fit a dose-response curve using a restricted cubic spline regression model.ResultsWe found 29 studies eligible to be included in our review. In the dose-response analysis, we found little association between disease risk and traffic indicators near the child's residence for most of the exposure range, with an indication of a possible excess risk only at the highest levels. In contrast, benzene exposure was positively and approximately linearly associated with risk of childhood leukemia, particularly for acute myeloid leukemia, among children under 6 y of age, and when exposure assessment at the time of diagnosis was used. Exposure to nitrogen dioxide showed little association with leukemia risk except at the highest levels.DiscussionOverall, the epidemiologic literature appears to support an association between benzene and childhood leukemia risk, with no indication of any threshold effect. A role for other measured and unmeasured pollutants from motorized traffic is also possible. https://doi.org/10.1289/EHP4381

Correção de fistula reto-uretral pela técnica de York-Mason

OBJECTIVE: Recto-urethral fistula formation following radical prostatectomy is an uncommon but potentially devastating event. There is no consensus in the literature regarding the treatment of these fistulas. We present here our experiences treating recto-urethral fistulas. MATERIAL AND METHODS: We analyzed 8 cases of rectourethral fistula treated at our institution in the last seven years. Seven of the patients underwent repair of the fistula using the modified York-Mason procedure. RESULTS: The causes of the fistula were radical retropubic prostatectomy in five patients, perineal debridement of Fournier's gangrene in one, transvesical prostatectomy in one and transurethral resection of the prostate in the other patient. The most common clinical manifestation was fecaluria, present in 87.5% of the cases. The mean time elapsed between diagnosis and correction of the fistula was 29.6 (7-63) months. One spontaneous closure occurred after five months of delayed catheterization. Urinary and retrograde urethrocystography indicated the site of the fistula in 71.4% of the cases. No patient presented recurrence of the fistula after its correction with the modified York-Mason procedure. CONCLUSION: The performance of routine colostomy and cystostomy is unnecessary. The technique described by York-Mason permits easy access, reduces surgical and hospitalization times and presents low complication and morbidity rates when surgically correcting recto-urethral fistulas.OBJETIVO: As fístulas reto-uretrais são de acesso difícil e por vezes complexo, sendo seu fechamento espontâneo raro. Com o diagnóstico precoce e aumento do número de intervenções, principalmente a cirurgia por adenocarcinoma da próstata localizado, sua incidência apesar de rara vem crescendo. Nós demonstramos a nossa experiência dos casos de fístulas reto-uretrais entre 2000 a 2006 com uma serie de oito pacientes, sendo que sete realizaram correção da fístula pela Técnica de York Mason modificada. MATERIAL E MÉTODO: Nos retrospectivamente analisamos os prontuários de todos os casos de fístulas reto-uretrais tratados no nosso serviço no período de 2000 a 2006. Sete de oito pacientes realizaram reparo da fístula através do procedimento de York Mason modificado. RESULTADOS: Cinco pacientes tiveram a fístula como conseqüência da Prostatectomia Radical Retropúbica, sendo os outros três após debridamento devido a Fasceíte de Fournier, Prostatectomia Transvesical e Ressecção Transuretral da Próstata. A fecalúria foi o quadro clínico prevalente em 87,5% dos casos, o tempo médio entre o diagnóstico e a correção da fístula foi de 29,6 (7-63 meses) ocorreu um fechamento espontâneo após cinco meses de sondagem vesical de demora, a Uretrocistografia Retrograda e Miccional demonstrou a localização da fístula em 71,4%. Nenhum paciente apresentou recidiva da fístula após correção pela técnica de York Mason modificada. A colostomia foi realizada em 50% dos casos e não ocorreram casos de incontinência fecal ou estenose anal. CONCLUÇÃO: Após identificação de fístula reto-uretral, não é necessário à realização de colostomia e cistostomia de rotina. Sua correção pela técnica descrita por York Mason modificada nos propicia fácil acesso a sua localização, diminui o tempo cirúrgico e de internação, com baixos índices de complicações e morbidade

Generalized Wasserstein distance and its application to transport equations with source

In this article, we generalize the Wasserstein distance to measures with different masses. We study the properties of such distance. In particular, we show that it metrizes weak convergence for tight sequences. We use this generalized Wasserstein distance to study a transport equation with source, in which both the vector field and the source depend on the measure itself. We prove existence and uniqueness of the solution to the Cauchy problem when the vector field and the source are Lipschitzian with respect to the generalized Wasserstein distance

Evaluation of European air quality modelled by CAMx including the volatility basis set scheme

Four periods of EMEP (European Monitoring and Evaluation Programme) intensive measurement campaigns (June 2006, January 2007, September-October 2008 and February-March 2009) were modelled using the regional air quality model CAMx with VBS (volatility basis set) approach for the first time in Europe within the framework of the EURODELTA-III model intercomparison exercise. More detailed analysis and sensitivity tests were performed for the period of February-March 2009 and June 2006 to investigate the uncertainties in emissions as well as to improve the modelling of organic aerosol (OA). Model performance for selected gas phase species and PM2.5 was evaluated using the European air quality database AirBase. Sulfur dioxide (SO2) and ozone (O-3) were found to be overestimated for all the four periods, with O-3 having the largest mean bias during June 2006 and January-February 2007 periods (8.9 pbb and 12.3 ppb mean biases respectively). In contrast, nitrogen dioxide (NO2) and carbon monoxide (CO) were found to be underestimated for all the four periods. CAMx reproduced both total concentrations and monthly variations of PM2.5 for all the four periods with average biases ranging from -2.1 to 1.0 mu g m(-3). Comparisons with AMS (aerosol mass spectrometer) measurements at different sites in Europe during February-March 2009 showed that in general the model overpredicts the inorganic aerosol fraction and underpredicts the organic one, such that the good agreement for PM2.5 is partly due to compensation of errors. The effect of the choice of VBS scheme on OA was investigated as well. Two sensitivity tests with volatility distributions based on previous chamber and ambient measurements data were performed. For February-March 2009 the chamber case reduced the total OA concentrations by about 42% on average. In contrast, a test based on ambient measurement data increased OA concentrations by about 42% for the same period bringing model and observations into better agreement. Comparison with the AMS data at the rural Swiss site Payerne in June 2006 shows no significant improvement in modelled OA concentration. Further sensitivity tests with increased biogenic and anthropogenic emissions suggest that OA in Payerne was affected by changes in emissions from residential heating during the February-March 2009 whereas it was more sensitive to biogenic precursors in June 2006.Peer reviewe

Comedouro semi-automático para porcas em lactação.

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