5,395 research outputs found
Influência da morfologia do terreno nas características do solo em terrenos agrícolas do Alentejo – aplicação de classificações geomorfométricas.
Neste artigo utiliza-se um Modelo de
Elevação Digital (MED) para elaborar e
comparar diferentes classificações da
morfologia do terreno quanto ao seu
potencial para a diferenciação da espessura e da textura do solo. As classificações
baseiam-se em observações de campo
(UTobs e PEobs-L) ou no cálculo de
variáveis geomorfométricas num MED
(UTx, UTx-L e PEx-L). Aplicam-se a
uma área localizada a 80 km a Este de
Évora, próximo de Terena, Alandroal,
numa parcela cultivada com milho regado
por rampa rotativa desde 1994 e com uma
morfologia ondulada em que os declives
variam entre 1% e 28%. Fez-se o levantamento topográfico baseado num sistema
de posicionamento global, a elaboração de
um MED e o cálculo de vários parâmetros
geomorfométricos de âmbito local e
regional. A amostragem do solo incidiu
em dois blocos (A e B), segundo uma
malha relativamente regular, recorrendo a
uma sonda mecânica cilíndrica com 87
mm de diâmetro e 120 cm de profundidade. Os resultados da espessura do solo e
da textura da camada 0-20 cm de 203
sondagens são usados para avaliar a
homogeneidade e a diferenciação das unidades de terreno (UT) obtidas com as
classificações morfológicas. Todas as
classificações testadas se revelaram pouco
eficientes a diferenciar os solos quanto à
granulometria. Os resultados foram
melhores na diferenciação das variáveis
de espessura, em especial a profundidade
máxima observada (PMX) e a profundidade até à camada R (PR), apresentandose as classificações pela seguinte sequência qualitativa: UTobs-L > PEobs-L >
PEx-L. As classificações por observação
de campo obtiveram melhores resultados,
mas as classificações geomorfométricas
baseadas em variáveis regionais (PEx-L)
foram melhores que as baseadas em
variáveis locais (UTx e UTx-L). No caso
da espessura, a eliminação de
UT < 100 m
2 melhorou sempre a resposta
das classificações
Constraining Elko Dark Matter at the LHC with Monophoton Events
A mass dimension one fermion, also known as Elko, constitutes a dark matter
candidate which might interact with photons at the tree level in a specific
fashion. In this work, we investigate the constraints imposed by unitarity and
LHC data on this type of interactions using the search for new physics in
monophoton events. We found that Elkos which can explain the dark matter relic
abundance mainly through electromagnetic interactions are excluded at the
95\%CL by the 8 TeV LHC data for masses up to 1 TeV.Comment: 6 pages, 4 figure
Sensitive and specific detection of Trypanosoma cruzi DNA in clinical specimens using a multi-target real-time PCR approach
Background: The laboratory diagnosis of Chagas disease is challenging because the usefulness of different diagnostic tests will depend on the stage of the disease. Serology is the preferred method for patients in the chronic phase, whereas PCR can be successfully used to diagnose acute and congenital cases. Here we present data using a combination of three TaqMan PCR assays to detect T. cruzi DNA in clinical specimens. Methods/Principal Findings: Included in the analysis were DNA extracted from 320 EDTA blood specimens, 18 heart tissue specimens, 6 umbilical cord blood specimens, 2 skin tissue specimens and 3 CSF specimens. For the blood specimens both whole blood and buffy coat fraction were analyzed. The specimens were from patients living in the USA, with suspected exposure to T. cruzi through organ transplantation, contact with triatomine bugs or laboratory accidents, and from immunosuppressed patients with suspected Chagas disease reactivation. Real-time PCR was successfully used to diagnose acute and Chagas disease reactivation in 20 patients, including one case of organ-transmitted infection and one congenital case. Analysis of buffy coat fractions of EDTA blood led to faster diagnosis in six of these patients compared to whole blood analysis. The three real-time PCR assays produced identical results for 94% of the specimens. The major reason for discrepant results was variable sensitivity among the assays, but two of the real-time PCR assays also produced four false positive results. Conclusions/Significance: These data strongly indicate that at least two PCR assays with different performances should be combined to increase the accuracy. This evaluation also highlights the benefit of extracting DNA from the blood specimen's buffy coat to increase the sensitivity of PCR analysis.Fil: Qvarnstrom, Yvonne. Centers for Disease Control and Prevention; Estados UnidosFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Veron, Vincent. Centre hospitalier Andrée-Rosemon; Guayana FrancesaFil: Aznar, Christine. Centre hospitalier Andrée-Rosemon; Guayana FrancesaFil: Steurer, Francis. Centers for Disease Control and Prevention; Estados UnidosFil: da Silva, Alexandre J.. Centers for Disease Control and Prevention; Estados Unido
Ensuring successful introduction of Wolbachia in natural populations of Aedes aegypti by means of feedback control
The control of the spread of dengue fever by introduction of the
intracellular parasitic bacterium Wolbachia in populations of the vector Aedes
aegypti, is presently one of the most promising tools for eliminating dengue,
in the absence of an efficient vaccine. The success of this operation requires
locally careful planning to determine the adequate number of individuals
carrying the Wolbachia parasite that need to be introduced into the natural
population. The introduced mosquitoes are expected to eventually replace the
Wolbachia-free population and guarantee permanent protection against the
transmission of dengue to human.
In this study, we propose and analyze a model describing the fundamental
aspects of the competition between mosquitoes carrying Wolbachia and mosquitoes
free of the parasite. We then use feedback control techniques to devise an
introduction protocol which is proved to guarantee that the population
converges to a stable equilibrium where the totality of mosquitoes carry
Wolbachia.Comment: 24 pages, 5 figure
Designed binary mixtures for subcritical organic Rankine cycles based on multiobjective optimization
The use of binary zeotropic mixtures as working fluids applied to Organic Rankine Cycles (ORCs) is investigated in this paper. In total, six (6) hydrocarbons and (2) hydrofluorocarbons are considered, leading to twenty-eight (28) possible binary combinations. The mixtures were tested with a basic Rankine cycle while using the heat source temperature as independent variable, which assumed six different values, ranging from 80 °C to 180 °C, in steps of 20 °C. The simulations aimed to identify the ideal mixtures that maximized the net power and exergetic efficiency, and minimized the heat exchanger’s global conductance for a given temperature of the heat source. The optimization process relied on a genetic algorithm and the selection of the best mixtures, on a non-dominated sorting method (NDS), which returned Pareto fronts gathering the best solutions. While no one specific ideal mixture was identified, the results showed that the range of the so-called ideal mixtures narrows as the heat source temperature increases, with mixtures including fluids like R245fa and pentane being good options, whereas at low temperature, a larger number of fluid mixtures perform well. Finally, a scale analysis is proposed and shows that the maximal net power varies linearly with a Number of Transfer Units (NTU) factor while its slope depends on the heat source temperature. The latter analysis is compared with the results obtained with the Pareto front and NDS, showing that both sets of results agree well while correlated by a single constant for the entire temperature range covered in the present study
Os atributos determinantes no acto médico de prescrição
JEL Classification: I110, I11, M31O propósito deste trabalho é identificar e compreender a hierarquia de preferências
estabelecida pela classe médica, em relação aos atributos determinantes no acto médico
de prescrição.
Para a realização desta investigação foram analisados trabalhos anteriores na mesma
área, servindo as evidências patenteadas pelos mesmos como base de sustentação da
proposta aqui apresentada. De entre os trabalhos existentes, destacamos o de Green,
Goldberg & Montemayor (1981), cuja metodologia foi agora seguida, com o intuito de
avaliar o processo de tomada de decisão do médico prescritor.
A população alvo de estudo foi a classe médica, tendo servido de base à investigação
empírica levada a efeito, uma amostra de cento e dois médicos que desenvolvem a sua
prática clínica em Portugal .
Os resultados obtidos demonstram de forma estatisticamente significativa, que existe
uma clara preocupação por parte dos médicos em privilegiar o uso dos produtos
farmacêuticos com maior eficácia demonstrada. É igualmente valorizado o papel que a marca institucional desempenha como variável de credibilização do produto a
prescrever.The purpose of this work is to identify and understand the preferential hierarchy
established by the medical class related to the determinant values in the medical act of
prescribing.
For the realization of this investigation we have analysed several previous works in this
area, using the shown evidence as a basis for this present purpose.
Among the existing works we have highlighted the one of Green, Goldberg and
Montemayor (1981), whose methodology is now followed, in order to evaluate doctor’s
decision process.
The medical class was the target population having used a 102 doctor’s sample as a
basis to this investigation who have developed their own practice in Portugal.
It is equally valuable that the institutional brand plays an important role in the product to be prescribed. The results obtained demonstrated in a significantly statistical way that there exists deep concern in giving privilege to the use of pharmaceutical products with higher demonstrated efficacy.
It likewise gives more value to the role that institutional brand has as a credibilization of the variable of the product to be prescribed
Resonant Lepton-Gluon Collisions at the Large Hadron Collider
We study the lepton-induced resonant production of color-adjoint leptons
(leptogluons) at the LHC employing the lepton parton density function of the
proton. We demonstrate that this production mechanism can be useful to extend
the LHC ability to search for leptogluons beyond purely quark/gluon initiated
production processes up to ~ 3.5 TeV leptogluon masses and O(1) TeV
compositeness scales. Discerning leptogluons from scalar and vector leptoquarks
is also possible in this channel, given a data sample containing the order of
100 signal events. We argue that the resonant channel can be combined with
leptogluon pair and associated leptogluon-lepton productions to boost exclusion
limits and discovery prospects at the LHC.Comment: 15 pages, 8 figure
Contact dynamics in a gently vibrated granular pile
We use multi-speckle diffusive wave spectroscopy (MSDWS) to probe the
micron-scale dynamics of a granular pile submitted to discrete gentle taps. The
typical time-scale between plastic events is found to increase dramatically
with the number of applied taps. Furthermore, this microscopic dynamics weakly
depends on the solid fraction of the sample. This process is strongly analogous
to the aging phenomenon observed in thermal glassy systems. We propose a
heuristic model where this slowing down mechanism is associated with a slow
evolution of the distribution of the contact forces between particles. This
model accounts for the main features of the observed dynamics.Comment: 4 pages, 4 figure
Genetic diversity of the sunflower caterpillar (Chlosyne lacinia saundersii Doubleday and Hewitson) ( Lepidoptera: Nymphalidae) populations determined by molecular RAPD markers.
Chlosyne lacinia saundersii is one of the most important pests of sunflower and it is the main target of insecticides applications. Larvae were collected in Londrina (PR), Santa Maria (RS), Dourados (MS), Ribeirão Preto (SP), Brasília (DF), Barreiras (BA), Uberaba (MG) and Vilhena (RO). Genomic DNA was extracted and amplified with ten-mer primers, which produced 101 loci. The size of the RAPD amplicons ranged from 180 to 2564 bp. Polymorphism among populations ranged from 31% to 67%, with the highest polymorphisms of 57% and 67% being detected in Uberaba and Vilhena populations, respectively. Populations with the highest similarity determined with Dice coefficient were from Ribeirão Preto and Barreiras, while insects from Londrina showed the highest similarity among them. Gene flow of C. lacinia saundersii 1.1 was lower than those previously observed for the noctuid Anticarsia gemmatalis Hübner, suggesting that C. lacinia saundersii populations are more isolated than the ones of this noctuid. Through the Analysis of Molecular Variance (AMOVA), RAPD variance was 33.64% among geographical populations and 66.36% within populations. These results suggest that populations of C. lacinia saundersii are genetically structured
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