779 research outputs found
Python I, II, and III CMB Anisotropy Measurement Constraints on Open and Flat-Lambda CDM Cosmogonies
We use Python I, II, and III cosmic microwave background anisotropy data to
constrain cosmogonies. We account for the Python beamwidth and calibration
uncertainties. We consider open and spatially-flat-Lambda cold dark matter
cosmogonies, with nonrelativistic-mass density parameter Omega_0 in the range
0.1--1, baryonic-mass density parameter Omega_B in the range (0.005--0.029)
h^{-2}, and age of the universe t_0 in the range (10--20) Gyr. Marginalizing
over all parameters but Omega_0, the combined Python data favors an open
(spatially-flat-Lambda) model with Omega_0 simeq 0.2 (0.1). At the 2 sigma
confidence level model normalizations deduced from the combined Python data are
mostly consistent with those drawn from the DMR, UCSB South Pole 1994, ARGO,
MAX 4 and 5, White Dish, and SuZIE data sets.Comment: 20 pages, 7 figures, accepted by Ap
Dilepton distributions at backward rapidities
The dilepton production at backward rapidities in and collisions
at RHIC and LHC energies is investigated in the dipole approach. The results
are shown through the nuclear modification ratio considering
transverse momentum and rapidity spectra. The dilepton modification ratio
presents interesting behavior at the backward rapidities when compared with the
already known forward ones, since it is related with the large kinematical
region that is being probed. The rapidity dependence of the nuclear
modification ratio in the dilepton production is strongly dependent on the
Bjorken behavior of the nuclear structure function ratio
. The transverse momentum dependence at
backward rapidities is modified due to the large nuclear effects: at RHIC
energies, for instance, the ratio is reduced as increases,
presenting an opposite behavior when compared with the forward one. It implies
that the dilepton production at backward rapidities should carry information of
the nuclear effects at large Bjorken , as well as that it is useful to
investigate the dependence of the observables in this kinematical regime.Comment: 15 pages, 6 figures. Version published in the Phys. Rev.
Experimental measuring procedure for the friction torque in rolling bearings
The reduction of the power loss generated in mechanical transmissions and the use of low friction biodegradable lubricants has been attracting considerable attention in recent times. Therefore, it is necessary to develop methods to test and evaluate the performance of such lubricants and compare them with conventional ones. In this sense, a Four-Ball Machine was modified allowing the test of rolling bearings. A 51107 thrust ball bearing was used to test two different greases and the corresponding base oils. Friction torque and operating temperatures were continuously monitored to quantify the power loss and the heat evacuation for each lubricant tested. Copyright (C) 2010 John Wiley & Sons, Ltd
Estudo da cadeia produtiva do processamento mecanico da madeira para prospeccao de demandas tecnologicas - analise das subcadeias das madeiras serrada e compensada no Estado do Paraná.
Propagação vegetativa da aroeira para palanques vivos: resultados preliminares.
Os resultados de um ensaio de campo demonstraram a viabilidade da aroeira (Schinus terebinthifolius Raddi) para a formação de cercas vivas. Foram testadas três classes de diâmetro, 40 estacas de 1,5 m de altura para cada classe, plantadas no espaçamento de 2,0 m x 2,0 m. Metade das estacas sofreram incisões na casca (1,0 cm, 10 cm e 20 cm da base) para verificação do seu efeito no enraizamento. Apesar do pegamento ter sido baixo (12%) constatou-se o potencial da espécie para esta prática, além da tendência das injúrias em beneficiar o enraizamento. Recomenda-se o seguimento das pesquisas, testando diferentes épocas do ano
X-Ray Diffraction and Raman Spectroscopic Studies of Glasses and Glass-Ceramics Inside the A2O-MoO3-Nb2O5-P2O5 (A= Li, Na) Systems
Phosphate glasses in the system (50-x)A2O-xMoO3-10Nb2O5-40P2O5 (AMo-40), with x=0; 30 and A=Li or Na were prepared by the melt quenching method. The effect in the crystallization behaviour of the glass due to the introduction of MoO3 in the glass composition and varying the molar ratio between network modifiers and network formers (M/F) was studied. The prepared glasses were heat-treated in air, at 550, 600 and 650 ºC for 4 hours. The structure, of the obtained samples, was studied by differential thermal analysis (DTA), X-ray powder diffraction (XRD), Raman spectroscopy and the morphology by scanning electron microscopy (SEM). It was found that the replacement of Li2O or Na2O by MoO3 reduces the number of the crystallised phases. In the lithium-niobiophosphate glasses the presence of MoO3 promotes the formation of NbOPO4 and reduces the formation of ortho- and pyro-phosphate phases. The thermal treatments affect the arrangements of the network structure of the AMo-40-glasses
Differences in prefrontal cortex activation and deactivation during strategic episodic verbal memory encoding in mild cognitive impairment
In this study we examined differences in fMRI activation and deactivation patterns during episodic verbal memory encoding between individuals with MCI (n = 18) and healthy controls (HCs) (n = 17). Participants were scanned in two different sessions during the application of self-initiated or directed instructions to apply semantic strategies at encoding of word lists. MCI participants showed reduced free recall scores when using self-initiated encoding strategies that were increased to baseline controls\u27 level after directed instructions were provided. During directed strategic encoding, greater recruitment of frontoparietal regions was observed in both MCI and control groups; group differences between sessions were observed in the ventromedial prefrontal cortex and the right superior frontal gyrus. This study provides evidence suggesting that differences of activity in these regions may be related to encoding deficits in MCI, possibly mediating executive functions during task performance
Non-isothermal model for the direct isotropic/smectic-A liquid crystalline transition
An extension to a high-order model for the direct isotropic/smectic-A liquid
crystalline phase transition was derived to take into account thermal effects
including anisotropic thermal diffusion and latent heat of phase-ordering.
Multi-scale multi-transport simulations of the non-isothermal model were
compared to isothermal simulation, showing that the presented model extension
corrects the standard Landau-de Gennes prediction from constant growth to
diffusion-limited growth, under shallow quench/undercooling conditions.
Non-isothermal simulations, where meta-stable nematic pre-ordering precedes
smectic-A growth, were also conducted and novel non-monotonic
phase-transformation kinetics observed.Comment: First revision: 20 pages, 7 figure
Transplantation tolerance: lessons from experimental rodent models
Immunological tolerance or functional unresponsiveness to a transplant is arguably the only approach that is likely to provide long-term graft survival without the problems associated with life-long global immunosuppression. Over the past 50 years, rodent models have become an invaluable tool for elucidating the mechanisms of tolerance to alloantigens. Importantly, rodent models can be adapted to ensure that they reflect more accurately the immune status of human transplant recipients. More recently, the development of genetically modified mice has enabled specific insights into the cellular and molecular mechanisms that play a key role in both the induction and maintenance of tolerance to be obtained and more complex questions to be addressed. This review highlights strategies designed to induce alloantigen specific immunological unresponsiveness leading to transplantation tolerance that have been developed through the use of experimental models
Blood Meal-Derived Heme Decreases ROS Levels in the Midgut of Aedes aegypti and Allows Proliferation of Intestinal Microbiota
The presence of bacteria in the midgut of mosquitoes antagonizes infectious agents, such as Dengue and Plasmodium, acting as a negative factor in the vectorial competence of the mosquito. Therefore, knowledge of the molecular mechanisms involved in the control of midgut microbiota could help in the development of new tools to reduce transmission. We hypothesized that toxic reactive oxygen species (ROS) generated by epithelial cells control bacterial growth in the midgut of Aedes aegypti, the vector of Yellow fever and Dengue viruses. We show that ROS are continuously present in the midgut of sugar-fed (SF) mosquitoes and a blood-meal immediately decreased ROS through a mechanism involving heme-mediated activation of PKC. This event occurred in parallel with an expansion of gut bacteria. Treatment of sugar-fed mosquitoes with increased concentrations of heme led to a dose dependent decrease in ROS levels and a consequent increase in midgut endogenous bacteria. In addition, gene silencing of dual oxidase (Duox) reduced ROS levels and also increased gut flora. Using a model of bacterial oral infection in the gut, we show that the absence of ROS resulted in decreased mosquito resistance to infection, increased midgut epithelial damage, transcriptional modulation of immune-related genes and mortality. As heme is a pro-oxidant molecule released in large amounts upon hemoglobin degradation, oxidative killing of bacteria in the gut would represent a burden to the insect, thereby creating an extra oxidative challenge to the mosquito. We propose that a controlled decrease in ROS levels in the midgut of Aedes aegypti is an adaptation to compensate for the ingestion of heme
- …