5,994 research outputs found
Fin loads and control-surface hinge moments measured in full-scale wind-tunnel tests on the X-24A flight vehicle
Fin loads and control surface hinge moments measured in full scale wind tunnel tests on X-24A flight vehicl
Exact Monte Carlo time dynamics in many-body lattice quantum systems
On the base of a Feynman-Kac--type formula involving Poisson stochastic
processes, recently a Monte Carlo algorithm has been introduced, which
describes exactly the real- or imaginary-time evolution of many-body lattice
quantum systems. We extend this algorithm to the exact simulation of
time-dependent correlation functions. The techniques generally employed in
Monte Carlo simulations to control fluctuations, namely reconfigurations and
importance sampling, are adapted to the present algorithm and their validity is
rigorously proved. We complete the analysis by several examples for the
hard-core boson Hubbard model and for the Heisenberg model
Large-scale albuminuria screen for nephropathy models in chemically induced mouse mutants
Background/Aim: Phenotype-driven screening of a great pool of randomly mutant mice and subsequent selection of animals showing symptoms equivalent to human kidney diseases may result in the generation of novel suitable models for the study of the pathomechanisms and the identification of genes involved in kidney dysfunction. Methods: We carried out a large-scale analysis of ethylnitrosourea (ENU)-induced mouse mutants for albuminuria by using qualitative SDS-polyacrylamide gel electrophoresis. Results: The primary albuminuria screen preceded the comprehensive phenotypic mutation analysis in a part of the mice of the Munich ENU project to avoid loss of mutant animals as a consequence of prolonged suffering from severe nephropathy. The primary screen detected six confirmed phenotypic variants in 2,011 G1 animals screened for dominant mutations and no variant in 48 G3 pedigrees screened for recessive mutations. Further breeding experiments resulted in two lines showing a low phenotypic penetrance of albuminuria. The secondary albuminuria screen was carried out in mutant lines which were established in the Munich ENU project without preceding primary albuminuria analysis. Two lines showing increased plasma urea levels were chosen to clarify if severe kidney lesions are involved in the abnormal phenotype. This analysis revealed severe albuminuria in mice which are affected by a recessive mutation leading to increased plasma urea and cholesterol levels. Conclusion: Thus, the phenotypic selection of ENU-induced mutants according to the parameter proteinuria in principle demonstrates the feasibility to identify nephropathy phenotypes in ENU-mutagenized mice. Copyright (C) 2005 S. Karger AG, Basel
Biological Principles in Self-Organization of Young Brain - Viewed from Kohonen Model
Variants of the Kohonen model are proposed to study biological principles of
self-organization in a model of young brain. We suggest a function to measure
aquired knowledge and use it to auto-adapt the topology of neuronal
connectivity, yielding substantial organizational improvement relative to the
standard model. In the early phase of organization with most intense learning,
we observe that neural connectivity is of Small World type, which is very
efficient to organize neurons in response to stimuli. In analogy to human brain
where pruning of neural connectivity (and neuron cell death) occurs in early
life, this feature is present also in our model, which is found to stabilize
neuronal response to stimuli
Avaliacao da eficiência de fungicidas no controle da cercosporiose (Cercospora zeae-maydis) na cultura do milho.
A cercosporiose do milho, causada pelo fungo Cercospora Zeae-maydis, é atualmente, no Brasil, uma das mais importantes doenças foliares dessa cultura, apresentando maior severidade de danos no sudoeste de Goiás. Este experimento foi conduzido em área de plantio direto de milho sobre milho, no município de Montividíu, ao, infectada com Cercospora zeae-maydis. O delineamento experimental foi o de blocos ao acaso, com 8 tratamentos em 4 repetições. Foi utilizado o híbrido simples Avant, de ciclo precoce. Os fungicidas foram aplicados mediante pulverizador manual pressurizado com 4 bicos pulverizadores. O volume de calda aplicado em cada parcela foi de I ,4 litros. Foram utilizados os seguintes fungicidas (g i.a.ha-1): propiconazole (100,0), propiconazole (125,0), difenoconazole (50,0), difenoconazole (75,0), azoxystrobin (50,0), azoxystrobin (75,0) e tebuconazole (200,0). Parcelas sem tratamento fungicida constituíram a testemunha. A primeira pulverização dos fungicidas foi realizada em plantas no estádio V8 (43 Dias Após o Plantio - DAP) e a segunda no estádio de pré_ emborrachamento (58 DAP). Aos 85 DAP, com plantas com espigas no estádio de grão pastoso, procedeu-se à avaliação dos sintomas foliares causados por Cercospora zeae-maydis, utilizando-se do seguinte esquema de notas: O =sem sintoma; 1 = poucas lesões nas folhas abaixo da espiga, nenhuma lesão acima; 2 = muitas lesões nas folhas abaixo da espiga, poucas lesões acima; 3 = severo desenvolvimento de lesões nas folhas abaixo da espiga, todas as folhas acima da espiga com lesões; 4 = todas as folhas com severo desenvolvimento de lesões, mas tecido verde ainda visível; 5 = todas as folhas secas e mortas. Os resultados obtidos mostram que os fungicidas propiconazole, difenoconazole, azoxystrobin e tebuconazole foram eficientes no controle da cercosporiose (Cercospora zeae-maydis) do milho e todos os tratamentos fungicida garantiram a produção de grãos de milho, sendo que a maior diferença percentual foi de 38,9% em relação à testemunha. Conclui-se que os fungicidas propiconazole, difenoconazole, azoxystrobin e tebuconazole são eficientes no controle da cercosporiose do milho causada por Cercospora zeae-maydis e que a aplicação destes produtos garantem significativamente a produção de grãos
Grid services for the MAGIC experiment
Exploring signals from the outer space has become an observational science
under fast expansion. On the basis of its advanced technology the MAGIC
telescope is the natural building block for the first large scale ground based
high energy gamma-ray observatory. The low energy threshold for gamma-rays
together with different background sources leads to a considerable amount of
data. The analysis will be done in different institutes spread over Europe.
Therefore MAGIC offers the opportunity to use the Grid technology to setup a
distributed computational and data intensive analysis system with the nowadays
available technology. Benefits of Grid computing for the MAGIC telescope are
presented.Comment: 5 pages, 1 figures, to be published in the Proceedings of the 6th
International Symposium ''Frontiers of Fundamental and Computational
Physics'' (FFP6), Udine (Italy), Sep. 26-29, 200
Stacked optical antennas for plasmon propagation in a 5 nm-confined cavity
The sub-wavelength concentration and propagation of electromagnetic energy are two complementary aspects of plasmonics that are not necessarily co-present in a single nanosystem. Here we exploit the strong nanofocusing properties of stacked optical antennas in order to highly concentrate the electromagnetic energy into a 5 nm metal-insulator-metal (MIM) cavity and convert free radiation into guided modes. The proposed nano-architecture combines the concentration properties of optical nanoantennas with the propagation capability of MIM systems, paving the way to highly miniaturized on-chip plasmonic waveguiding
Cellular response to 5-fluorouracil (5-FU) in 5-FU-resistant colon cancer cell lines during treatment and recovery
BACKGROUND: Treatment of cells with the anti-cancer drug 5-fluorouracil (5-FU) causes DNA damage, which in turn affects cell proliferation and survival. Two stable wild-type TP53 5-FU-resistant cell lines, ContinB and ContinD, generated from the HCT116 colon cancer cell line, demonstrate moderate and strong resistance to 5-FU, respectively, markedly-reduced levels of 5-FU-induced apoptosis, and alterations in expression levels of a number of key cell cycle- and apoptosis-regulatory genes as a result of resistance development. The aim of the present study was to determine potential differential responses to 8 and 24-hour 5-FU treatment in these resistant cell lines. We assessed levels of 5-FU uptake into DNA, cell cycle effects and apoptosis induction throughout treatment and recovery periods for each cell line, and alterations in expression levels of DNA damage response-, cell cycle- and apoptosis-regulatory genes in response to short-term drug exposure. RESULTS: 5-FU treatment for 24 hours resulted in S phase arrests, p53 accumulation, up-regulation of p53-target genes on DNA damage response (ATF3, GADD34, GADD45A, PCNA), cell cycle-regulatory (CDKN1A), and apoptosis-regulatory pathways (FAS), and apoptosis induction in the parental and resistant cell lines. Levels of 5-FU incorporation into DNA were similar for the cell lines. The pattern of cell cycle progression during recovery demonstrated consistently that the 5-FU-resistant cell lines had the smallest S phase fractions and the largest G(2)(/M) fractions. The strongly 5-FU-resistant ContinD cell line had the smallest S phase arrests, the lowest CDKN1A levels, and the lowest levels of 5-FU-induced apoptosis throughout the treatment and recovery periods, and the fastest recovery of exponential growth (10 days) compared to the other two cell lines. The moderately 5-FU-resistant ContinB cell line had comparatively lower apoptotic levels than the parental cells during treatment and recovery periods and a recovery time of 22 days. Mitotic activity ceased in response to drug treatment for all cell lines, consistent with down-regulation of mitosis-regulatory genes. Differential expression in response to 5-FU treatment was demonstrated for genes involved in regulation of nucleotide binding/metabolism (ATAD2, GNL2, GNL3, MATR3), amino acid metabolism (AHCY, GSS, IVD, OAT), cytoskeleton organization (KRT7, KRT8, KRT19, MAST1), transport (MTCH1, NCBP1, SNAPAP, VPS52), and oxygen metabolism (COX5A, COX7C). CONCLUSION: Our gene expression data suggest that altered regulation of nucleotide metabolism, amino acid metabolism, cytoskeleton organization, transport, and oxygen metabolism may underlie the differential resistance to 5-FU seen in these cell lines. The contributory roles to 5-FU resistance of some of the affected genes on these pathways will be assessed in future studies
Gluten-free diet and gut microbiome
As the only effective therapy against diagnosed celiac disease (CD), the gluten-free diet (GFD) has inevitable repercussion on the gut microbiome composition and functionality. Being the cause or the consequence of the disease, an altered homeostasis of the gut microbiome usually affects CD patients at diagnosis. After describing the main features of this altered physiological condition, this review defines the main nutritional aspects of the GFD and elucidates how this diet regimen does not fully restore the optimal gut microbiome composition and functionality. Unbalanced ratios between beneficial and potentially harmful bacteria are frequently present in fecal materials, biopsy specimens and saliva, used as ecological model systems to observe CD. Metabolome analyses also show how an altered microbiome synthesize different metabolite with respect to healthy conditions. The review concludes illustrating the current supplementations (biotics family), which fortify the GFD with the aim of restoring the homeostasis of the gut microbiome
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