1,780 research outputs found
Flavor conversion of cosmic neutrinos from hidden jets
High energy cosmic neutrino fluxes can be produced inside relativistic jets
under the envelopes of collapsing stars. In the energy range E ~ (0.3 - 1e5)
GeV, flavor conversion of these neutrinos is modified by various matter effects
inside the star and the Earth. We present a comprehensive (both analytic and
numerical) description of the flavor conversion of these neutrinos which
includes: (i) oscillations inside jets, (ii) flavor-to-mass state transitions
in an envelope, (iii) loss of coherence on the way to observer, and (iv)
oscillations of the mass states inside the Earth. We show that conversion has
several new features which are not realized in other objects, in particular
interference effects ("L- and H- wiggles") induced by the adiabaticity
violation. The neutrino-neutrino scattering inside jet and inelastic neutrino
interactions in the envelope may produce some additional features at E > 1e4
GeV. We study dependence of the probabilities and flavor ratios in the
matter-affected region on angles theta13 and theta23, on the CP-phase delta, as
well as on the initial flavor content and density profile of the star. We show
that measurements of the energy dependence of the flavor ratios will, in
principle, allow to determine independently the neutrino and astrophysical
parameters.Comment: 56 pages, 19 figures. Minor changes. Accepted by JHEP
Risk Factors for Soil-Transmitted Helminth Infections during the First 3 Years of Life in the Tropics; Findings from a Birth Cohort.
Background: Soil-transmitted helminths (STH) infect more than 2 billion humans worldwide, causing significant morbidity in children. There are few data on the epidemiology and risk factors for infection in pre-school children. To investigate risk factors for infection in early childhood, we analysed data prospectively collected in the ECUAVIDA birth cohort in Ecuador.
Methods and Findings:
Children were recruited at birth and followed up to 3 years of age with periodic collection of stool samples that were examined microscopically for STH parasites. Data on social, demographic, and environmental risk factors were collected from the mother at time of enrolment. Associations between exposures and detection of STH infections were analysed by multivariable logistic regression. Data were analysed from 1,697 children for whom a stool sample was obtained at 3 years. 42.3% had at least one STH infection in the first 3 years of life and the most common infections were caused by A. lumbricoides (33.2% of children) and T. trichiura (21.2%). Hookworm infection was detected in 0.9% of children. Risk of STH infection was associated with factors indicative of poverty in our study population such as Afro-Ecuadorian ethnicity and low maternal educational level. Maternal STH infections during pregnancy were strong risk factors for any childhood STH infection, infections with either A. lumbricoides or T. trichiura, and early age of first STH infection. Children of mothers with moderate to high infections intensities with A. lumbricoides were most at risk.
Conclusions:
Our data show high rates of infection with STH parasites during the first 3 years of life in an Ecuadorian birth cohort, an observation that was strongly associated with maternal STH infections during pregnancy. The targeted treatment of women of childbearing age, in particular before pregnancy, with anthelmintic drugs could offer a novel approach to the prevention of STH infections in pre-school children
Avaliação de genótipos de capim-elefante para uso forrageiro e produção de biomassa energética no Estado de Sergipe.
Atualmente, a biomassa responde por cerca de 30% da matriz energética nacional, representada pelo consumo de bagaço de cana, lenha e carvão vegetal, álcool e outras fontes primárias renováveis. São várias as formas de energia que se pode obter a partir da biomassa. Os principais usos da biomassa como insumo energético são a produção de energia térmica, produção de energia mecânica, produção de energia. No entanto, nos últimos anos, vem sendo desenvolvida uma nova técnica para substituição do carvão mineral, pelo carvão derivado de biomassa seca de capim elefante. O presente trabalho teve como objetivo geral selecionar clones de capim elefante para obtenção e registro de novas cultivares, que apresentem elevada produção de biomassa energética e com adaptação à s diferentes condições edafoclimáticas dos Tabuleiros Costeiros. Esta sendo realizada a seleção massal estratifi cada em uma população de capim-elefante no municÃpio de Nossa Senhora das Dores, SE. Foram selecionados 79 genótipos, que foram clonados, onde foram avaliados em ensaio utilizando delineamento simples, considerando-se os cortes como repetições. Os genótipos serão avaliados pelo perÃodo mÃnimo de dois anos. Foi avaliada a produção de matéria seca e verde de planta inteira; altura da planta; número de perfi lhos. Os melhores genótipos serão enviados para avaliação no plano de ação da Renace. As médias das variáveis de altura de planta, número de perfi lhos, produção de massa verde e produção de massa seca por corte, referente à s avaliações efetuadas nos meses de novembro de 2013 e maio de 2014. Para altura obtivemos de 240 a 440 cm, número de perfi lhos de 61 a 86 perfi lhos/m, massa verde variou de 37.774 193.314 kg/ha e massa seca de 8.920 a 54.547 kg/há. No geral pode-se dizer que a partir da análise dos dados dos dois cortes os resultados foram promissores, apesar da necessidade de mais avaliações e estudos para que possamos obter resultados mais significativos. Apesar de haver indÃcios de clones onde o desempenho foi consideravelmente expressivo é necessário a continuidade das avaliações para a obtenção de resultados mais significativos
Ancient DNA SNP-panel data suggests stability in bluefin tuna genetic diversity despite centuries of fluctuating catches in the eastern Atlantic and Mediterranean
Atlantic bluefin tuna (Thunnus thynnus; BFT) abundance was depleted in the late 20th and early 21st century due to overfishing. Historical catch records further indicate that the abundance of BFT in the Mediterranean has been fluctuating since at least the 16th century. Here we build upon previous work on ancient DNA of BFT in the Mediterranean by comparing contemporary (2009–2012) specimens with archival (1911–1926) and archaeological (2nd century BCE–15th century CE) specimens that represent population states prior to these two major periods of exploitation, respectively. We successfully genotyped and analysed 259 contemporary and 123 historical (91 archival and 32 archaeological) specimens at 92 SNP loci that were selected for their ability to differentiate contemporary populations or their association with core biological functions. We found no evidence of genetic bottlenecks, inbreeding or population restructuring between temporal sample groups that might explain what has driven catch fluctuations since the 16th century. We also detected a putative adaptive response, involving the cytoskeletal protein synemin which may be related to muscle stress. However, these results require further investigation with more extensive genome-wide data to rule out demographic changes due to overfishing, and other natural and anthropogenic factors, in addition to elucidating the adaptive drivers related to these
Previsão do teor de proteÃna bruta e digestibilidade da silagem de mandioca por meio da espectroscopia NIR.
Resumo: O cultivo da mandioca é amplamente difundido na região nordeste, tendo grande importância na alimentação de pequenos rebanhos. Uma boa alternativa para a época de seca é a silagem da parte área da mandioca, que apresenta valores significativos de proteÃnas, vitaminas e minerais. Contudo o valor desses compostos podem apresentar variações advindas do processo de fermentação. Para garantir a presenças destes compostos na silagem é necessário que se faça a analise bromatológica, que pode ter alto custo e demandar grande quantidade de tempo, assim, não sendo viável ao produtor. Uma alternativa ao uso das analises tradicionais é o uso da espectroscopia de reflectância na região do infravermelho próximo (NIRS), por ser uma tecnologia de alta precisão e acurácia, que é econômica e sustentável. Objetivou-se com este trabalho avaliar modelos para previsão de proteÃna bruta (PB), digestibilidade in vitro da matéria seca (DIVMS).Edición de las Memorias de la 25a. Reunión de la Asociación Latinoamericana de Producción Animal (ALPA), 2016, Recife, Brasil
Anisotropy at the end of the cosmic ray spectrum?
The starburst galaxies M82 and NGC253 have been proposed as the primary
sources of cosmic rays with energies above eV. For energies \agt
10^{20.3} eV the model predicts strong anisotropies. We calculate the
probabilities that the latter can be due to chance occurrence. For the highest
energy cosmic ray events in this energy region, we find that the observed
directionality has less than 1% probability of occurring due to random
fluctuations. Moreover, during the first 5 years of operation at Auger, the
observation of even half the predicted anisotropy has a probability of less
than to occur by chance fluctuation. Thus, this model can be subject
to test at very small cost to the Auger priors budget and, whatever the outcome
of that test, valuable information on the Galactic magnetic field will be
obtained.Comment: Final version to be published in Physical Review
Global characteristics and outcomes of SARS-CoV-2 infection in children and adolescents with cancer (GRCCC): a cohort study
BACKGROUND: Previous studies have shown that children and adolescents with COVID-19 generally have mild disease. Children and adolescents with cancer, however, can have severe disease when infected with respiratory viruses. In this study, we aimed to understand the clinical course and outcomes of SARS-CoV-2 infection in children and adolescents with cancer. METHODS: We did a cohort study with data from 131 institutions in 45 countries. We created the Global Registry of COVID-19 in Childhood Cancer to capture de-identified data pertaining to laboratory-confirmed SARS-CoV-2 infections in children and adolescents (<19 years) with cancer or having received a haematopoietic stem-cell transplantation. There were no centre-specific exclusion criteria. The registry was disseminated through professional networks through email and conferences and health-care providers were invited to submit all qualifying cases. Data for demographics, oncological diagnosis, clinical course, and cancer therapy details were collected. Primary outcomes were disease severity and modification to cancer-directed therapy. The registry remains open to data collection. FINDINGS: Of 1520 submitted episodes, 1500 patients were included in the study between April 15, 2020, and Feb 1, 2021. 1319 patients had complete 30-day follow-up. 259 (19·9%) of 1301 patients had a severe or critical infection, and 50 (3·8%) of 1319 died with the cause attributed to COVID-19 infection. Modifications to cancer-directed therapy occurred in 609 (55·8%) of 1092 patients receiving active oncological treatment. Multivariable analysis revealed several factors associated with severe or critical illness, including World Bank low-income or lower-middle-income (odds ratio [OR] 5·8 [95% CI 3·8-8·8]; p<0·0001) and upper-middle-income (1·6 [1·2-2·2]; p=0·0024) country status; age 15-18 years (1·6 [1·1-2·2]; p=0·013); absolute lymphocyte count of 300 or less cells per mm3 (2·5 [1·8-3·4]; p<0·0001), absolute neutrophil count of 500 or less cells per mm3 (1·8 [1·3-2·4]; p=0·0001), and intensive treatment (1·8 [1·3-2·3]; p=0·0005). Factors associated with treatment modification included upper-middle-income country status (OR 0·5 [95% CI 0·3-0·7]; p=0·0004), primary diagnosis of other haematological malignancies (0·5 [0·3-0·8]; p=0·0088), the presence of one of more COVID-19 symptoms at the time of presentation (1·8 [1·3-2·4]; p=0·0002), and the presence of one or more comorbidities (1·6 [1·1-2·3]; p=0·020). INTERPRETATION: In this global cohort of children and adolescents with cancer and COVID-19, severe and critical illness occurred in one fifth of patients and deaths occurred in a higher proportion than is reported in the literature in the general paediatric population. Additionally, we found that variables associated with treatment modification were not the same as those associated with greater disease severity. These data could inform clinical practice guidelines and raise awareness globally that children and adolescents with cancer are at high-risk of developing severe COVID-19 illness. FUNDING: American Lebanese Syrian Associated Charities and the National Cancer Institute
Avaliação da qualidade da fermentação de silagem de mandioca por meio da espectroscopia NIR.
Resumo: A ensilagem é um método de conservação de forragem que pode garantir a alimentação do rebanho no perÃodo seco e tem sido largamente utilizada pelos produtores. A silagem da parte área da mandioca tem se mostrado como um alimento com bom potencial nutritivo. Contudo, sua qualidade não está relacionada apenas com o valor bromatológico, mas também com a eficiência de fermentação. Esta pode ser avaliada a partir dos valores de pH e NH3 (amônia). Valores superiores a 10% de NH3 do valor de nitrogênio total indicam fermentação indesejada, gerando dificuldade na conservação. Os valores de pH e NH3 podem ser estimados a partir de analises quÃmicas tradicionais que demandam uma escala significativa de tempo, de custos e reagentes, dentre outros fatores que tornam analises tradicionais inviáveis aos produtores rurais. Neste cenário, o uso da espectroscopia de reflectância na região do infravermelho próximo (NIRS) tem se demonstrado uma ferramenta alternativa aos métodos convencionais para determinar a qualidade da fermentação de silagem. O presente trabalho objetivou avaliar modelos para previsão de pH e NH3 em silagem de mandioca.Edición de las Memorias de la 25a. Reunión de la Asociación Latinoamericana de Producción Animal (ALPA), 2016, Recife, Brasil
The clustering of ultra-high energy cosmic rays and their sources
The sky distribution of cosmic rays with energies above the 'GZK cutoff'
holds important clues to their origin. The AGASA data, although consistent with
isotropy, shows evidence for small-angle clustering, and it has been argued
that such clusters are aligned with BL Lacertae objects, implicating these as
sources. It has also been suggested that clusters can arise if the cosmic rays
come from the decays of very massive relic particles in the Galactic halo, due
to the expected clumping of cold dark matter. We examine these claims and show
that both are in fact not justified.Comment: 13 pages, 8 figures, version in press at Phys. Rev.
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