580 research outputs found
Otimização da diagnose molecular de vĂrus, bactĂ©ria e fungo em cana-de-açĂșcar.
RESUMO: Visando Ă otimização da diagnose molecular de plĂąntulas de cana-de-açĂșcar, tentou-se desenvolver iniciadores especĂficos para escaldadura e ferrugem alaranjada, assim como a comparação da PCR comum e a PCR em Tempo Real (PCR/TR) de maior resolução, importante para doenças com grande perĂodo de latĂȘncia, como as causadas por: 1- BactĂ©rias, (a) raquitismo-da-soqueira (Leifsonina xyli subsp. Xyli) e (b) escaldadura (Xanthomonas aibilineans); 2- VĂrus, (a) amarelinho (Sugarcane Yellow Leaf VĂrus); (b) mosaico (Sugarcane Mosaic VĂrus) e (c) fijivirus (Fiji disease vĂrus); 3- fungo, (a) carvĂŁo (Sporisorium scitamineum) e (b) ferrugem alaranjada (Puccinia kuehnii). As plĂąntulas foram obtidas do quarentenĂĄrio do IAC. Os iniciadores da literatura para cana-de-açĂșcar detectaram especificamente o raquitismo, amarelinho, mosaico e fijivirus, enquanto os desenvolvidos para PCR/TR para as mesmas doenças, incluindo a escaldadura e ferrugem alaranjada, possibilitaram a detecção com maior diluição das amostras. Os iniciadores da ferrugem alaranjada, alĂ©m de nĂŁo detectarem a ferrugem marrom, tambĂ©m diferenciaram a ferrugem branca do milho. Os da escaldadura nĂŁo foram especĂficos somente para o gĂȘnero Erwinia, enquanto que os da literatura nĂŁo diferenciaram tambĂ©m outras espĂ©cies dos gĂȘneros Kanthomonas, Pseudomonas, Enwinia, Stenotrophomona e Pantoea. A otimização das diluiçÔes para PCR/TR a partir de cDNA foi de apenas lOX. PorĂ©m, para extratos de DNA de planta, foi maior, de lOOX a lOOOX,indicando a maior sensibilidade do mĂ©todo. Dos 28 pares de iniciadores testados, os melhores para o agente causal de cada doença e curvas de diluiçÔes (com eficiĂȘncia de PCR de 1,05 a 1,28) sĂŁo apresentados
AnĂĄlises moleculares de bactĂ©rias e fungo em cana-de-açĂșcar.
RESUMO: A cana-de-açĂșcar Ă© uma das principais culturas do Brasil, que Ă© o maior produtor mundial de açĂșcar e ĂĄlcool. A cultura da cana-de-açucar Ă© extremamente vulnerĂĄvel a doenças devido ao sistema de propagação por toletes facilitar a disseminação dos patĂłgenos, uma vez que os colmos mesmo infectados podem nĂŁo apresentar sintomas. A propagação dessas doenças em monoculturas em grandes ĂĄreas facilita as epidemias, sendo importante para o plantio de mudas sadias, mĂ©todos para a detecção precoce de doenças. Dentre as doenças mais importantes em cana-de-açĂșcar, sĂŁo conhecidas as causadas por bactĂ©rias como a Leifsonia xyli subsp.xyli, agente causal do Raquitismo-da-soqueira ou ?ratoon stunting disease? (RSD) e a Xanthomonas albilineans, responsĂĄvel pela Escaldadura das folhas ou ?sugarcarne leaf scald? (Ashby); por fungo como o do carvĂŁo (Ustilago scitaminea) que Ă© uma doença considerada em todos os programas de melhoramento genĂ©tico, com longo perĂodo de latĂȘncia. Foram utilizadas como amostras folhas de plĂąntulas de cana-açĂșcar desenvolvidas de cultura de tecido com cerca de 2 meses de transplante. Foram utilizados iniciadores de literatura para raquitismo e escaldadura ou desenvolvido pelo laboratĂłrio para carvĂŁo. Os fragmentos amplificados de cada doença foram clonados e a identidade confirmada por BLAST. O DNA dos controles positivos das reaçÔes foi obtido de clones dos fragmentos amplificados de plantas infectadas. Os iniciadores desenvolvidos para carvĂŁo mostraram especificidade em amostras de folhas de plĂąntulas de cana-de-açĂșcar. A detecção de infecção confirma a eficĂĄcia da metodologia em plĂąntulas com 2 meses de transplante, assim como o uso de clones como controle positivo, a maior facilidade para diagnostico de infecção em plĂąntulas de cana-de-açĂșcar
Fatores associados a desfechos desfavorĂĄveis apĂłs trauma craniano leve pediĂĄtrico em um centro de referĂȘncia da regiĂŁo norte de Minas Gerais
Study Design: Prospective cohort. Objective: To describe clinical and demographic characteristics of a sample of children with HI referred for acute care in a referral center of the north region of Minas Gerais, Brazil, and assess clinical and radiological markers associated with unfavorable outcomes. Methodology: All children between the ages 0 to 14 years referred with head injury from February to September 2011 were included in this study. Socio-demographic and clinical data were collected at the moment of the initial assessment under informed consent. The patients were also reassessed via telephone calls after 7 and 91 days. Results: A total of 77 patients were included in this study. The mean age was 3.9 years with a standard deviation of 3.76 years. Falls and bicycle collisions were the main mechanisms of trauma. The most relevant clinical marker associated with unfavorable outcomes at 7 days was the parental perception of unusual behavior (Odds Ratio = 11.33; 95% confidence interval: 1.38-93.13; p = 0.02). Computer tomography scan abnormalities were associated with both unfavorable outcomes at 7 days (p=0.03) and at 91 days (p=0.02). Conclusions: The peculiar aspects of head injuries in a Brazilian population were described in this study. It was also found that unusual behavior and abnormalities on CT scan are factors that predict unfavorable outcomes in children with mild HI in this population.Modelo do Estudo: Coorte prospectivo. Objetivo do Estudo: Descrever caracterĂsticas clĂnicas e demogrĂĄficas de uma amostra de crianças encaminhadas por traumatismo craniano em um centro de referĂȘncia na regiĂŁo norte de Minas Gerais e avaliar marcadores clĂnicos e radiolĂłgicos associados a desfechos desfavorĂĄveis. Metodologia: Foram incluĂdas neste estudo todas as crianças entre 0 e 14 anos atendidas com traumatismo craniano de fevereiro a setembro de 2011. Dados sĂłcio demogrĂĄficos e clĂnicos foram coletados no momento da avaliação inicial sob consentimento informado. Os pacientes tambĂ©m foram reavaliados por telefone apĂłs 7 e 91 dias. Resultados: Um total de 77 pacientes foi incluĂdo neste estudo. A idade mĂ©dia foi de 3,9 anos, com desvio padrĂŁo de 3,76 anos. Quedas e colisĂ”es de bicicleta foram os principais mecanismos de trauma. O marcador clĂnico mais relevante associado a desfechos desfavorĂĄveis com 7 dias foi a percepção pelos pais de comportamento anormal (Odds Ratio = 11,3; intervalo de confiança de 95%: 1,38-93,13; p = 0,02). AlteraçÔes na Tomografia Computadorizada foram associadas tanto a desfechos desfavorĂĄveis apĂłs 7 dias (p=0,03) como apĂłs 91 dias (p=0,02). ConclusĂ”es: Os aspectos peculiares do traumatismo craniano em uma população brasileira sĂŁo descritos neste estudo. Encontrou-se, ainda, que um comportamento anormal e alteraçÔes na TC sĂŁo fatores que predizem desfechos desfavorĂĄveis em crianças com traumatismo craniano leve nessa população
Attention on Weak Ties in Social and Communication Networks
Granovetter's weak tie theory of social networks is built around two central
hypotheses. The first states that strong social ties carry the large majority
of interaction events; the second maintains that weak social ties, although
less active, are often relevant for the exchange of especially important
information (e.g., about potential new jobs in Granovetter's work). While
several empirical studies have provided support for the first hypothesis, the
second has been the object of far less scrutiny. A possible reason is that it
involves notions relative to the nature and importance of the information that
are hard to quantify and measure, especially in large scale studies. Here, we
search for empirical validation of both Granovetter's hypotheses. We find clear
empirical support for the first. We also provide empirical evidence and a
quantitative interpretation for the second. We show that attention, measured as
the fraction of interactions devoted to a particular social connection, is high
on weak ties --- possibly reflecting the postulated informational purposes of
such ties --- but also on very strong ties. Data from online social media and
mobile communication reveal network-dependent mixtures of these two effects on
the basis of a platform's typical usage. Our results establish a clear
relationships between attention, importance, and strength of social links, and
could lead to improved algorithms to prioritize social media content
BRS Novaera: cultivar de feijĂŁo-caupi de porte semi-ereto.
bitstream/item/27806/1/Com.Tec.215.pdfDisponĂvel tambĂ©m on-line
Mass Enhancement in an Intermediate-Valent Regime of Heavy-Fermion Systems
We study the mechanism of the mass enhancement in an intermediate-valent
regime of heavy-fermion materials. We find that the crossovers between the
Kondo, intermediate valent, and almost empty f-electron regimes become sharp
with the Coulomb interaction between the conduction and f electrons. In the
intermediate-valent regime, we find a substantial mass enhancement, which is
not expected in previous theories. Our theory may be relevant to the observed
nonmonotonic variation in the effective mass under pressure in CeCu2Si2 and the
mass enhancement in the intermediate-valent compounds alpha-YbAlB4 and
beta-YbAlB4.Comment: 4 pages, 4 figure
A search for point sources of EeV photons
Measurements of air showers made using the hybrid technique developed with
the fluorescence and surface detectors of the Pierre Auger Observatory allow a
sensitive search for point sources of EeV photons anywhere in the exposed sky.
A multivariate analysis reduces the background of hadronic cosmic rays. The
search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an
energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been
detected. An upper limit on the photon flux has been derived for every
direction. The mean value of the energy flux limit that results from this,
assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial
direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in
which EeV cosmic ray protons are emitted by non-transient sources in the
Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical
Journa
Reconstruction of inclined air showers detected with the Pierre Auger Observatory
We describe the method devised to reconstruct inclined cosmic-ray air showers
with zenith angles greater than detected with the surface array of
the Pierre Auger Observatory. The measured signals at the ground level are
fitted to muon density distributions predicted with atmospheric cascade models
to obtain the relative shower size as an overall normalization parameter. The
method is evaluated using simulated showers to test its performance. The energy
of the cosmic rays is calibrated using a sub-sample of events reconstructed
with both the fluorescence and surface array techniques. The reconstruction
method described here provides the basis of complementary analyses including an
independent measurement of the energy spectrum of ultra-high energy cosmic rays
using very inclined events collected by the Pierre Auger Observatory.Comment: 27 pages, 19 figures, accepted for publication in Journal of
Cosmology and Astroparticle Physics (JCAP
Gutzwiller Method for an Extended Periodic Anderson Model with the c-f Coulomb Interaction
We study an extended periodic Anderson model with the Coulomb interaction Ucf
between conduction and f electrons by the Gutzwiller method. The crossovers
between the Kondo, intermediate-valence, and almost empty f-electron regimes
become sharper with Ucf, and for a sufficiently large Ucf, become first-order
phase transitions. In the Kondo regime, a large enhancement in the effective
mass occurs as in the ordinary periodic Anderson model without Ucf. In
addition, we find that a large mass enhancement also occurs in the
intermediate-valence regime by the effect of Ucf.Comment: 9 pages, 7 figure
- âŠ