574 research outputs found
Caracterização de marcador do tipo EST-SSR associado com resistência ao bicho-mineiro.
Um dos fatores que limitam o desenvolvimento de novas cultivares de cafeeiro por Programas de Melhoramento é a dificuldade de seleção precoce para características agronômicas superiores. Atualmente, marcadores moleculares são utilizados, em diferentes espécies de plantas, como uma ferramenta alternativa e eficiente para seleção de tais características. Portanto, a identificação de marcadores moleculares do tipo microsatélite (ssr) que co-segreguem com a resistência ao bicho-mineiro representa um avanço para seleção assistida. Neste estudo, foram identificados marcadores ssr expressos, através de buscas dirigidas aos bancos de ESTs de cafeeiro. Para caracterização dos marcadores EST-SSR, foi avaliada a expressão destes em genótipos resistentes e suscetíveis infestados com bicho-mineiro, através da metodologia de RT-PCR. Dentre os locos EST-SSR investigados um deles apresentou padrão diferencial, uma vez que folhas suscetíveis não apresentaram expressão do loco. O loco foi clonado e seqüenciado, a partir de genótipos resistentes e suscetíveis. Análises das sequências permitiram a identificação de 11 alelos, contendo vários polimorfismos de tamanho da repetição e do tipo SNPs. No entanto, nenhum destes polimorfismos apresentou co-relação com a característica de resistência. Análises em andamento visam a caracterização deste loco expresso
Expressão de genes relacionados ao metabolismo de nitrogênio, fósforo de potássio em cafeeiros submetidos ao estresse biótico.
As plantas freqüentemente são ameaçadas por agentes externos que podem ser fatores bióticos e/ou abióticos. Para cada tipo de ameaça há um requintado tipo de resposta que caracteriza o processo de defesa. Dentre os processos de defesa enquadram-se a ativação ou repressão de genes relacionados como quitinases, glucanaes, lipoxigenases, transferases, entre outros. Quaisquer modificações bioquímicas que ocorram durante os ataques dos patógenos são indispensáveis para a compreensão deste mecanismo biológico. Correlacionar os mecanismos biológicos de regulação e transporte de íons com os diferentes períodos de infestação e infecção é uma dessas maneiras de elucidar os processos que ocorrem durante a infestação e infecção. Neste estudo foram analisados os perfis de expressão de 5 genes (HAK-5, KEA, PAP-1, PII, NTR) relacionados com o transporte e regulação de potássio e nitrogênio com diferentes estímulos bióticos e em diferentes etapas de cada um desses processos. Os resultados demonstraram que há padrões diferenciais de regulação entre as plantas suscetíveis e resistentes para todos os genes analisados. Estas análises preliminares indicam que a regulação da absorção e/ou transporte de nutrientes exerce um importante papel durante as respostas de defesa em cafeeiros contra o bicho mineiro
Standardizing effect size from linear regression models with log-transformed variables for meta-analysis
Background: Meta-analysis is very useful to summarize the effect of a treatment or a risk factor for a given disease.
Often studies report results based on log-transformed variables in order to achieve the principal assumptions of a
linear regression model. If this is the case for some, but not all studies, the effects need to be homogenized.
Methods: We derived a set of formulae to transform absolute changes into relative ones, and vice versa, to allow
including all results in a meta-analysis. We applied our procedure to all possible combinations of log-transformed
independent or dependent variables. We also evaluated it in a simulation based on two variables either normally or
asymmetrically distributed.
Results: In all the scenarios, and based on different change criteria, the effect size estimated by the derived set of
formulae was equivalent to the real effect size. To avoid biased estimates of the effect, this procedure should be
used with caution in the case of independent variables with asymmetric distributions that significantly differ from
the normal distribution. We illustrate an application of this procedure by an application to a meta-analysis on the
potential effects on neurodevelopment in children exposed to arsenic and manganese.
Conclusions: The procedure proposed has been shown to be valid and capable of expressing the effect size of a
linear regression model based on different change criteria in the variables. Homogenizing the results from different
studies beforehand allows them to be combined in a meta-analysis, independently of whether the transformations
had been performed on the dependent and/or independent variables
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
Charge separation relative to the reaction plane in Pb-Pb collisions at TeV
Measurements of charge dependent azimuthal correlations with the ALICE
detector at the LHC are reported for Pb-Pb collisions at TeV. Two- and three-particle charge-dependent azimuthal correlations in
the pseudo-rapidity range are presented as a function of the
collision centrality, particle separation in pseudo-rapidity, and transverse
momentum. A clear signal compatible with a charge-dependent separation relative
to the reaction plane is observed, which shows little or no collision energy
dependence when compared to measurements at RHIC energies. This provides a new
insight for understanding the nature of the charge dependent azimuthal
correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286
Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at , 2.76 and 7 TeV
Measurements of the sphericity of primary charged particles in minimum bias
proton--proton collisions at , 2.76 and 7 TeV with the ALICE
detector at the LHC are presented. The observable is linearized to be collinear
safe and is measured in the plane perpendicular to the beam direction using
primary charged tracks with GeV/c in . The
mean sphericity as a function of the charged particle multiplicity at
mid-rapidity () is reported for events with different
scales ("soft" and "hard") defined by the transverse momentum of the leading
particle. In addition, the mean charged particle transverse momentum versus
multiplicity is presented for the different event classes, and the sphericity
distributions in bins of multiplicity are presented. The data are compared with
calculations of standard Monte Carlo event generators. The transverse
sphericity is found to grow with multiplicity at all collision energies, with a
steeper rise at low , whereas the event generators show the
opposite tendency. The combined study of the sphericity and the mean with multiplicity indicates that most of the tested event generators
produce events with higher multiplicity by generating more back-to-back jets
resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with
tune PERUGIA-2011 exhibits a noticeable improvement in describing the data,
compared to the other tested generators.Comment: 21 pages, 9 captioned figures, 3 tables, authors from page 16,
published version, figures from
http://aliceinfo.cern.ch/ArtSubmission/node/308
A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE
In this small note we are concerned with the solution of Forward-Backward
Stochastic Differential Equations (FBSDE) with drivers that grow quadratically
in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem
is a comparison result that allows comparing componentwise the signs of the
control processes of two different qgFBSDE. As a byproduct one obtains
conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
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