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Search Results: 1 - 10 of 74515 matches for " Michael;Santos "
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Probing reionization with Lyman-alpha emission lines
Michael R. Santos
Physics , 2003, DOI: 10.1111/j.1365-2966.2004.07594.x
Abstract: Lyman-alpha emission from high-redshift galaxies may be a powerful probe of the ionization history of the IGM at z>6: the observed Lyman-alpha emission line is sensitive to the neutral fraction of IGM hydrogen in the range 0.1-1. We present calculations of observed Lyman-alpha emission lines from z>6 galaxies, illustrating the effect of varying the many free parameters associated with the emitting galaxy, its halo, and the IGM around the galaxy. In particular, we use a dynamic model of the IGM that includes the effect of IGM infall toward the emitting galaxy. Galactic winds may play a crucial role in determining observed Lyman-alpha line fluxes. We compare our model predictions with observations of two z=6.5 galaxies and conclude that, if galactic winds are allowed for, existing observations place no constraint on the neutral fraction of the IGM at z=6.5. Future space-based observations will constrain the importance of galactic winds; if winds are unimportant for the observed z=6.5 galaxies, our models suggest that the IGM neutral fraction at z=6.5 is <~0.1.
"Os charruas vivem" nos Gaúchos: a vida social de uma pesquisa de "resgate" genético de uma etnia indígena extinta no Sul do Brasil
Kent, Michael;Santos, Ricardo Ventura;
Horizontes Antropológicos , 2012, DOI: 10.1590/S0104-71832012000100015
Abstract: this paper aims to explore the articulation between genetic ancestry research and social constructions of ethnic identity in the state of rio grande do sul. it will do so by analysing the social life of a research project conducted at the ufrgs that established genetic continuity between the contemporary gaúcho population and the assumedly extinct indigenous charrua. in the course of time, this idea of genetic continuity has taken on different incarnations, within varying contexts, and affirmed with differing levels of certainty. this paper will focus on the social and genetic conditions that have enabled the establishment of such continuity, as well as the affirmation of the genetic distinctiveness of the gaúchos. finally, it will explore the social impacts of this research, in particular its articulation with constructions of a differentiated regional identity.
A method to infer the stellar population that dominated the UV background at the end of reionization
Michael R. Santos,Abraham Loeb
Physics , 2003,
Abstract: We present an observational test of the spectrum of the ionizing background at z~5; the test is sufficiently sensitive to determine whether Pop II or Pop III stars are the dominant source of ionizing radiation. The ionizing background at z~5 may reflect the nature of the sources responsible for the final overlap phase of reionization. We find that rest-frame extreme-UV HeI absorption will be detectable in deep spectral observations of some rare z~5 quasars; the ratio of HeI to HI absorption reflects the shape of the ionizing background in the photon energy range between 13.6 and 24.6 eV. Most z~5 quasars have too much HI absorption along their line of sight for HeI absorption to be observed. However, based on current measurements of HI absorber statistics, we use Monte Carlo simulations to demonstrate that the Sloan Digital Sky Survey (SDSS) will discover a sufficient number of z~5 quasars to turn up a quasar suitable for measuring HeI absorption (and we illustrate a selection method to identify that quasar). From simulated observations of a suitable z~5 quasar with a 10-meter telescope, we show that a constraint on the spectral slope of the ionizing background at that redshift can be obtained.
Cinryze as the first approved C1 inhibitor in the USA for the treatment of hereditary angioedema: approval, efficacy and safety
Michael Lunn, Carah Santos, Timothy Craig
Journal of Blood Medicine , 2010, DOI: http://dx.doi.org/10.2147/JBM.S9576
Abstract: ryze as the first approved C1 inhibitor in the USA for the treatment of hereditary angioedema: approval, efficacy and safety Review (3069) Total Article Views Authors: Michael Lunn, Carah Santos, Timothy Craig Published Date August 2010 Volume 2010:1 Pages 163 - 170 DOI: http://dx.doi.org/10.2147/JBM.S9576 Michael Lunn1, Carah Santos2, Timothy Craig1 1Penn State Hershey Section of Allergy, Asthma and Immunology, Hershey, PA USA; 2Stanford University Department of Pediatrics, Palo Alto, CA USA Abstract: Hereditary angioedema (HAE) is a clinical disorder characterized by a deficiency of C1 esterase inhibitor (C1-INH). HAE has traditionally been divided into two subtypes. Unique among the inherited deficiencies of the complement system, HAE Types I and II are inherited as an autosomal dominant disorder. The generation of an HAE attack is caused by the depletion and/or consumption of C1-inhibitor manifested as subcutaneous or submucosal edema of the upper airway, face, extremities, or gastrointestinal tract. Attacks can be severe and potentially life-threatening, particularly with laryngeal involvement. Despite the availability of C1-INH for the treatment of HAE since the 1980s in Europe and other countries, HAE treatment in the United States was limited to androgen therapy. The human plasma-derived C1 esterase -inhibitor (CinryzeTM), distributed by Lev Pharmaceuticals, was approved in October 2008 for the -prevention of HAE attacks based on the results of a phase III clinical trial. This review aims to describe the history of C1-INH replacement in HAE as well as the pharmacology, efficacy and safety of C1-INH, concentrating on Cinryze as the first approved chronic replacement treatment for the prophylaxis of HAE attacks.
Two-dimensional scattering and bound states of polar molecules in bilayers
Michael Klawunn,Alexander Pikovski,Luis Santos
Physics , 2010, DOI: 10.1103/PhysRevA.82.044701
Abstract: Low-energy two-dimensional scattering is particularly sensitive to the existence and properties of weakly-bound states. We show that interaction potentials $V(r)$ with vanishing zero-momentum Born approximation $\int d^2r V(r)=0$ lead to an anomalously weak bound state which crucially modifies the two-dimensional scattering properties. This anomalous case is especially relevant in the context of polar molecules in bilayer arrangements.
The Contribution of the First Stars to the Cosmic Infrared Background
Michael R. Santos,Volker Bromm,Marc Kamionkowski
Physics , 2001, DOI: 10.1046/j.1365-8711.2002.05895.x
Abstract: We calculate the contribution to the cosmic infrared background from very massive metal-free stars at high redshift. We explore two plausible star-formation models and two limiting cases for the reprocessing of the ionizing stellar emission. We find that Population III stars may contribute significantly to the cosmic near-infrared background if the following conditions are met: (i) The first stars were massive, with M > ~100 M_sun. (ii) Molecular hydrogen can cool baryons in low-mass haloes. (iii) Pop III star formation is ongoing, and not shut off through negative feedback effects. (iv) Virialized haloes form stars at about 40 per cent efficiency up to the redshift of reionization, z~7. (v) The escape fraction of the ionizing radiation into the intergalactic medium is small. (vi) Nearly all of the stars end up in massive black holes without contributing to the metal enrichment of the Universe.
Designing an Online Geospatial System for Forest Resource Management  [PDF]
Peter G. Oduor, Michael Armstrong, Larry Kotchman, Michael Kangas, Buddhika Maddurapperuma, Kelsey Forward, Pubudu Wijeyaratne, Xiana Santos, Akiko Nakamura, Krystal Leidholm
Journal of Geographic Information System (JGIS) , 2014, DOI: 10.4236/jgis.2014.63019
Abstract:

Geographic and Geospatial information systems (GISs) have especially benefited from increased development of their inherent capabilities and improved deployment. These systems offer a wide range of services, for example, user-friendly forms that interact with the geospatial components for locational information and geographic extents. An online distributed platform was designed for forest resource management with map elements residing on a GIS platform. This system is accessible on non-authenticated browsers optimized for desktops; whereas the online resource management forms are also accessible on mobile platforms. The system was primarily designed to aid foresters in implementing resource management plans or track threats to forest resource. Baseline data from the system can be easily visualized and mapped. Other data from the systemcan provide input for stochastic analyses especially with respect to forest resource management.

Theoretical Investigation on the Solubilization in Water of Functionalized Single-Wall Carbon Nanotubes
Michael Mananghaya,Emmanuel Rodulfo,Gil Nonato Santos,Al Rey Villagracia
Journal of Nanotechnology , 2012, DOI: 10.1155/2012/780815
Abstract: An important technique to increase the solubility and reactivity of carbon nanotube is through functionalization. In this study, the effects of functionalization of some single-walled carbon nanotubes (SWCNTs) were investigated with the aid of density functional theory. The SWCNT model used in the study consists of a finite, (5, 0) zigzag nanotube segment containing 60 C atoms with hydrogen atoms added to the dangling bonds of the perimeter carbons. There are three water-dispersible SWCNTs used in this study that were functionalized with (a) formic acid, as a model of carboxylic acid, (b) isophthalic acid, as a model aromatic dicarboxylic acid, and (c) benzenesulfonic acid, as a model aromatic sulfonic acid. Binding energies of the organic radicals to the nanotubes are calculated, as well as the HOMO-LUMO gaps and dipole moments of both nanotubes and functionalized nanotubes. Binding was found out to be thermodynamically favorable. The functionalization increases the electrical dipole moments and results in an enhancement in the solubility of the nanotubes in water manifested through favorable changes in the free energies of solvation. This should lower the toxicity of nanotubes and improve their biocompatibility. 1. Introduction Single-walled carbon nanotubes (SWCNTs) are allotropes of carbon and possess various novel properties that make them useful in the field of nanotechnology and pharmaceuticals. SWCNTs are tubular in shape, made of graphite, nanometers in diameter, and several millimeters in length and have a very broad range of electronic, thermal, and structural properties. These properties vary with the kind of nanotubes defined by its diameter, length, chirality or twist, and wall nature. Their unique surface area, stiffness, strength, and resilience have led to much excitement in the field of pharmacy. Nanostructured materials hold promise for a wide range of technological applications and are increasingly studied, not only for their possible applications in electronics, optics and mechanical materials, but also specifically having enormous potential in nanomedicine [1–11]. Because of this, it is imperative to examine the toxicity of these carbon-based nanostructures. Previous toxicological evaluations of single-walled carbon nanotubes have been conducted, both in cell culture and in vivo. One example, using an SWCNT surfactant stabilized system where the Fe content was significantly high, reported an elevated cytotoxic response [12]. Warheit et al. [13] observed an increase in inflammatory response in the lung cavities of rats. While these
Lutzomyia aldafalcaoae sp. n. a new species of Phlebotominae (Diptera: Psychodidae) from Mato Grosso do Sul, Brazil
Santos, Soraya Oliveira;Andrade Filho, José Dilermando;Honer, Michael R;
Memórias do Instituto Oswaldo Cruz , 2001, DOI: 10.1590/S0074-02762001000600009
Abstract: a new sand fly species, lutzomia aldafalcaoae is described from males collected in vila trindade, an urban district in aquidauana county, state of mato grosso do sul, brazil, in october 1996. taxonomic remarks and a description of the new species is presented.
Padr?o de afilhamento em arroz afetado pela presen?a dos íons am?nio e nitrato
Poletto, Naracelis;Mundstock, Claudio Mario;Grohs, Daniel Santos;Mazurana, Michael;
Bragantia , 2011, DOI: 10.1590/S0006-87052011000100015
Abstract: rice development is affected by nitrogen, specially its tillering pattern which is determined by number of tillers. tillers synchronism with main stem is related to leaves emission rate and both traits affect the number of productive culms potential. tiller emission and synchronism of leaf development between main stem and tillers were studied in rice plants (cv irga 417) cultivated in a hydroponic solution (hoagland) under three n concentrations (1, 5 e 10 mmol l-1), each with different proportion of n-nh4+ and n-no3- (100:0; 75:25; 50:50; 25:75). the different proportions under 1 mmol l-1 were similar for tiller number, synchronism, and productive culms. all traits (tiller number, synchronism and productive culms) were negatively affected when higher levels of n-nh4+ ion (5 and 10 mmol l-1 - 100 and 75% of n ions) were supplied to plants. nevertheless, when n-no3- ion was present in at least 50% of the solution, the detrimental effects were not found. when n was at 1 mmol l-1, rice plants tolerate n-nh4+ ion presence, independently of the presence of n-no3- ion. at higher n concentrations, it is necessary at least 50% of n-no3- ion in order to avoid detrimental effects on tillering.
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