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Search Results: 1 - 10 of 11393 matches for " Rafael; "
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Sustainable and Economic Alternative for the Electric Supply of Isolated Communities in the Brazilian Off-Grid Systems  [PDF]
Rebeca Doctors, Rafael Kelman
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.59012
Abstract: Roughly 99% of the demand for electricity in Brazil is supplied by a national interconnected grid. The remaining 1% is spread in several “isolated systems” of the Amazon region—mini-grids that rely on expensive diesel gensets due to high commodity and transportation costs. The isolated systems also have remote communities disconnected altogether from the mini-grids with inadequate health, education and leisure services. These communities are precariously supplied by small inefficient diesel gensets that run for a few hours per day. In this article, we propose a sustainable and economic alternative for the electric supply of the remote communities of isolated systems through a combination of photovoltaic solar generation and storage. The objective is to improve access to electricity with savings for the communities. The present paper outlines a public policy to meet this objective.
The Difference in Calcium Levels in Aspergillus nidulans Grown on Glucose or Pectin  [PDF]
Janice Aparecida Rafael, Suraia Said
Advances in Microbiology (AiM) , 2012, DOI: 10.4236/aim.2012.22016
Abstract: Understanding the growth regulatory mechanisms in filamentous fungi is very important for the production of medicines for antifungal therapies. It is well established that Ca2+ gradient is essential for hyphal growth and that one mechanism responsible for the Ca2+ cellular concentration starts with the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) by receptor-regulated forms of phosphoinositide-specific phospholipase C (PI-PLC). In the present study the levels of calcium in Aspergillus nidulans wild type (A26) and plcA-deficient mutant (AP27) growing in a carbon source readily assimilated, as glucose or pectin a non-readily assimilated carbon source was investigated. Intracellular calcium levels in A26 were higher in the presence of glucose than in pectin, but lower in AP27 independently of the carbon source and in AP27 the vesicular calcium distribution occurred mainly at the apex of the hyphae. Delay in nuclear division was also observed if A26 and AP27 were grown in pectin presence when compared with growth in glucose. For the first time, it is demonstrated that the levels of intracellular Ca2+ were higher when A. nidulans was growing in glucose than in a non readily assimilated carbon source as pectin. Further, it also showed that the plcA gene, although not essential, may be responsible for high-molecular weight carbon source recongnation, for the intracellular Ca2+ levels maintenance and consequently by the nuclear division in A. nidulans.
Evaluation of Inherent Uncertainties of the Homogeneous Effective Thermal Conductivity Approach in Modeling of Printed Circuit Boards for Space Applications  [PDF]
Rafael Lopes Costa, Valeri Vlassov
Journal of Electronics Cooling and Thermal Control (JECTC) , 2013, DOI: 10.4236/jectc.2013.31005

Electronic components are normally assembled to printed circuit boards (PCBs). Such components generate heat in operation which must be conducted away efficiently from the small mounting areas to frames where the PCB is fixed. The temperature of the component depends on heat dissipation rate, technology and parameters of mounting, component placement and finally effective thermal conductivity (keff) of the board. The temperature of some components may reach significant magnitudes over 100°C while the PCB frame is kept at near-ambient temperature. The reliability of electronic components is directly related to operating temperature; so the thermal project should be able to provide a correct temperature prediction of all PCB components under the hottest operational condition. In space applications, the main way to spread and reject heat of electronic equipment is by thermal conduction once there is no air available to apply convection-based cooling techniques. The PCB keff is an important parameter for the electronics thermal analysis when the PCB is modeled as a simplified homogeneous board with a unique thermal conductivity. In this paper, an intrinsic uncertainty of such approach is firstly reveled and its magnitude is evaluated for a real space use PCB. The simulation uses SINDA/FLUINT Thermal Desktop and aims to determine the keff of the PCB by comparison between a detailed multi-layered anisotropic model and an

Experimental Evidence of Capillary Interruption of a Liquid Jet  [PDF]
Taha Massalha, Rafael M. Digilov
Open Journal of Applied Sciences (OJAppS) , 2014, DOI: 10.4236/ojapps.2014.47037
Abstract: We observe the gravity discharge of liquid through the short cylindrical tube of diameter of 2 mm and aspect ratio 2.5 and 10 attached to the underside of Mariotte bottle. When the hydrostatic head is reduced and approaches to a certain value, a laminar jet escaped from the nozzle is interrupted and the discharge is drop wise. The plot of the discharge rate as a function of hydrostatic head does not pass through the origin as predicted by Torricelli law for an ideal liquid. We attribute this feature to the energy losses related with creating a new free surface area of the jet. The measurements for water and aqueous ethanol solution are compared with theoretical predictions based on the modified Bernoulli equation with the interfacial energy density correction and good agreement is observed.
Restricted partitions
Rafael Jakimczuk
International Journal of Mathematics and Mathematical Sciences , 2004, DOI: 10.1155/s0161171204306502
Abstract: We prove a known partitions theorem by Bell in an elementary and constructive way. Our proof yields a simple recursive method to compute the corresponding Sylvester polynomials for the partition. The previous known methods to obtain these polynomials are in general not elementary.
“Anecdotal Evidence”: Why Narratives Matter to Medical Practice
Rafael Campo
PLOS Medicine , 2006, DOI: 10.1371/journal.pmed.0030423
ICU cornerstone: 'triggering effort'
Rafael Fernandez
Critical Care , 2002, DOI: 10.1186/cc1875
Abstract: The most frequent reason for admission to an intensive care unit is need for ventilatory assistance. At least, this is my experience over the past 20 years from working in university and county hospitals. Regardless of the illness that provokes respiratory insufficiency, the majority of patients with respiratory failure eventually require mechanical ventilation. If there is an improvement in oxygenation after a few days, then we are forced to consider reducing the intensity of ventilatory support. In the early years of my critical care training, when we checked ventilated patients under the effects of low-level sedation and were attempting to wean them off ventilation, such patients normally had to make an effort to trigger the ventilator. At that time, our teachers told us that this was normal; 'it is a kind of exercise training' said one, and 'it is our way of finding out which patients can work harder' said another. It was not clear why the 'trigger knob' had always to be in the standard position (not too difficult or too easy). One of my mentors told me to take advantage of the triggering effort because he thought that this effort could be related to a sophisticated parameter used in respiratory physiology, namely the occlusion pressure, or P0.1. After that, I started conducting research by obtaining many recordings of airflow and airway pressure in intubated, ventilated patients while they attempted to breathe. My mentor was right, and we published some stimulating papers about the 'triggering effort' [1].Nevertheless, patients continued having to work to breathe while they were on the ventilator. When I reviewed our experimental tracings, I realized that patient response was not so predictable. Each patient had his or her own pattern of response, and most of them started inspiration before finishing expiration. At that time, not much was known about this type of patient response. We looked at these results again and made new tracings in different patients. Amo
Epistemología y ciencia de la información
ACIMED , 2010,
Abstract: in the introduction the concept of paradigm as well as the scope of epistemological research in information science are analized. the first part mentions some epistemological paradigms that have influenced information science so far, such as hermeneutics, critical rationalism, critical theory, semiotics, constructivism, second-order cybernetics, and system theory. the second part is dedicated to the analysis of three epistemological paradigms in information science starting with the physical paradigm that goes back to shannon's theory of communication. the cranfield tests and michael buckland's conception of "information-as-thing" are mentioned. the second paradigm is the cognitive one (b.c. brookes, nicholas belkin, pertti vakkari, peter ingwersen). the third paradigm is the social one which goes back to jesse shera's "social epistemology," and is represented today by scholars such as bernd frohmann, birger hj?rland, s?ren brier and the author himself. practical consequences of epistemological research concerning the design and evaluation of information systems as well as research in information science are considered.
Análisis de abundancia, distribución y tallas de tiburones capturados por pesca artesanal en el parque nacional archipiélago los roques, Venezuela
Interciencia , 2009,
Abstract: relative abundance, distribution and length structure of sharks were examined based on specimens caught during 2001 and 2002 by the artisanal shark fishery from los roques archipelago national park. a total of 13 species of sharks were reported during the study period, in which carcharhinus limbatus (47.9%) and c. perezi (37.7%) were the most common frequently caught. ginglymostoma cirratum, c. falciformis and negaprion brevirostris together comprised 10.7% of the shark catch. the fishing effort was primarily concentrated during the third quarter in both years of the study period, and in the depth strata of < 10 m. general mean cpue showed that the most abundant species were c. limbatus (2,76 ind 100-anz-1 ± 2,43 ds) and c. perezi (2,35 ind 100-anz-1 ± 2,17 ds). c. limbatus catches were constituted by individuals measuring between 53 and 218 cm tl. however, 96.5% of those caught were juveniles captured within the central lagoon of the archipelago. the catches of c. perezi were represented by individuals with sizes between 67 and 270 cm tl, and the 82.6% of them were juveniles captured in shallow water zones near the islands. the present study showed that the los roques archipelago is an important nursery area for the species c. limbatus and c. perezi. the protection of the nursery areas of sharks, as a conservation measure, should be promoted in the study area.
Pabellones Parque Independencia Rosario, Argentina
ARQ (Santiago) , 2005, DOI: 10.4067/S0717-69962005005900011
Abstract: our faith in so-called progress draws us unresisting to new trends, new materials, new practices. the logic that discounts a priori the old or the existing works in opposition to other, archaic, brutal solutions that still trust to piling up and compression, disregarding the accelerated cycles of technical obsolescence. stones, wedges and logs, un-jointed, unchanging, balance the load against the forces of gravity.
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