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Search Results: 1 - 10 of 5481 matches for " Xavier "
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On the Communication Requirements for the Smart Grid  [PDF]
Mohamed Daoud, Xavier Fernando
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.31008
Abstract: The current power grid is facing many challenges that it was not designed or engineered to handle which range from congestions and major blackouts to the overwhelming increase in demand and security concerns. The current electric grid was established before the 1960’s. It is believed that the electric grid is the most complex and gigantic machine ever made in human history; it consists of wires, cables, towers, transformers and circuit breakers installed together in outdated manner. During the 60’s, computers and sensors were used to monitor and slightly control the grid; however, fifty years later these sensors are considered less than ideal. Presented here is a review of the smart grid communication network in terms of configuration, bandwidth and latency requirements as well as the technology used. We simulate the access layer of the smart grid net-work and show that no single available communication technology can be used for all layers of the smart grid; thus, different technologies for different layers are needed. A new protocol for optimizing the smart grid is recommended.
On the zeros and critical points of a rational map
Xavier Buff
International Journal of Mathematics and Mathematical Sciences , 2001, DOI: 10.1155/s0161171201011589
Abstract: Let f:ℙ1→ℙ1 be a rational map of degree d. It is well known that f has d zeros and 2d−2 critical points counted with multiplicities. In this note, we explain how those zeros and those critical points are related.
How does BAFF activate B cells in patients with autoimmune diseases?
Xavier Mariette
Arthritis Research & Therapy , 2012, DOI: 10.1186/ar3729
Abstract: In a study in a recent issue of Arthritis Research & Therapy, Yoshimoto and colleagues [1] demonstrate that peripheral monocytes from patients with Sj?gren's syndrome (SS) produce significantly higher amounts of the cytokines B cell-activating factor (BAFF) (also called B-lymphocyte stimulator, or BlyS) and interleukin-6 (IL-6) in comparison with normal monocytes. Increased expression of BAFF might explain pathogenic B-cell activation in several systemic autoimmune diseases (reviewed in [2]). Interestingly, autoreactive B cells depend more on BAFF for survival than do alloreactive B cells. BAFF involvement in the pathogenesis of autoimmune diseases is well illustrated in BAFF-transgenic mice, which exhibit an autoimmune disease mimicking systemic lupus erythematosus (SLE) and primary Sj?gren's syndrome (pSS) as well as a twofold increase in frequency of B-cell lymphoma [3]. In humans, an increased serum level of BAFF was reported in different autoimmune diseases, and findings concerning SLE and pSS were more consistent (reviewed in [2]).Recent findings showed that BAFF could be expressed and secreted by resident cell targets of autoimmunity after stimulation with different cytokines: synoviocytes in rheumatoid arthritis, astrocytes in multiple sclerosis, and epithelial cells in pSS [4]. Moreover, in the context of autoimmunity, BAFF could be secreted by T [5] and B [6] lymphocytes. However, the main sources of BAFF are myeloid cells and, especially, blood monocytes, myeloid dendritic cells, and macrophages [7].It has been suggested that monocytes from patients with autoimmune diseases were more susceptible to BAFF expression and secretion after stimulation with type 1 interferon (IFN) than those from healthy controls [8]. Yoshimoto and colleagues [1] add an important point to this discussion by emphasizing the role of monocytes in the overproduction of BAFF in autoimmunity. The authors demonstrate that peripheral pSS monocytes produce significantly higher amounts of
A Phase Space Diagram for Gravity
Xavier Hernandez
Entropy , 2012, DOI: 10.3390/e14050848
Abstract: In modified theories of gravity including a critical acceleration scale a 0, a critical length scale rM = (GM/a 0 )1/2 will naturally arise with the transition from the Newtonian to the dark matter mimicking regime occurring for systems larger than rM. This adds a second critical scale to gravity, in addition to the one introduced by the criterion v < c of the Schwarzschild radius, rS = 2GM/c2. The distinct dependencies of the two above length scales give rise to non-trivial phenomenology in the (mass, length) plane for astrophysical structures, which we explore here. Surprisingly, extrapolation to atomic scales suggests gravity should be at the dark matter mimicking regime there.
Seleno-enzymes and seleno-compounds: the two faces of selenium
Xavier Forceville
Critical Care , 2006, DOI: 10.1186/cc5109
Abstract: Biological and medical advances in the area of selenium provide interest in selenium for both its antioxidant properties through seleno-enzyme incorporation, as illustrated in the previous issue of Critical Care [1], and its direct pro-oxidant toxic effect through seleno-compounds.In intensive care, and especially in septic shock adjunctive therapy, there is a growing interest in the antioxidant role of selenium [2-5]. We know that there is a very low level of selenium in the human (20 mg for the whole body) but that a severe deficiency is lethal [6]. We also know that selenium plays a crucial role in antioxidant defense, as one selenium atom is absolutely required at the active site of all seleno-enzymes in the form of the 21-amino-acid selenocystein [6,7]. Mammals largely use seleno-enzymes for antioxidant purposes, whereas bacteria do not. The seleno-enzymes are ubiquitous in mammal cells and have two main roles. Firstly, the seleno-enzymes protect cell components against oxidation: membranes, enzymes, proteins, and DNA. Secondly, seleno-enzymes inhibit proinflammatory cell metabolisms by reducing the peroxide tone of intracellular water (NF-κB, acid arachidonic and complement cascades, and mitochondria) [6,8]. As a consequence, selenium has been found to improve immunity [6,7]. In septic shock patients there is a dramatic and early decrease of the plasma selenium concentration [9].In the previous issue of Critical Care, Berger and colleagues [1] reported the results of a very interesting aggregative study on a group of 41 severely burnt patients. The authors show a significant reduction of nosocomial pneumonia by intravenous multitrace-element supplements (copper, selenium, and zinc). These results confirm Berger's research on burnt and trauma patients conducted since 1986 [4]. This particular population has lower mortality than septic shock patients [2].The approach of these studies is to increase the antioxidant defense by supplementing patients with multimicr
Bacterial genomics in Spain
Xavier Bosch
Genome Biology , 2003, DOI: 10.1186/gb-spotlight-20040405-01
Abstract: The Network of Bacterial Genomics (RGB), made up of 41 research teams at universities, hospitals, and centers of the Higher Research Council, will allow scientists to share human and technical resources in an effort to understand the genetic roots of bacterial pathogenicity and utility.The network, whose creation was announced last week (March 23), aims to create a critical mass of researchers in the field to allow them, among other things, to apply for joint research projects. Fellows and senior researchers will move freely among the different centers to build their skills not only in the lab but also in bioinformatics. It is planned to organize periodical meetings and congresses of Spanish and foreign researchers.Central to the initiative is the collaboration of five biotech companies - Biomeda, Progenika, Noraybio, Bioalma, and Newbiotech - which will provide the necessary genetic and bioinformatics tools to the scientists.The RGB idea emerged in February in a meeting at the Valencia-based Institute of Cytologic Research. In the meeting, "it became clear that Spain has the capacity to start projects of bacterial genomics," Andrés Moya, head of the University of Valencia's Institute Cavanilles for Biodiversity and Evolutionary Biology, told us. "It's a pity that, given our potential in this area, we can say that our country has contributed to the sequencing of only two microorganisms out of dozens sequenced so far."It was Moya's team that sequenced the genomes of Buchnera aphidicola and Blochmannia floridanus. Moya argues that there is the "wrong perception by managers of national research programs that work in genomics ends with the sequence of a model genome."Comparative genomics analysis, sequencing, and bioinformatics should be added to the "key words already applied to national programs," he adds.Francisco Rodríguez-Valera, at Universidad Miguel Hernández in San Juan de Alicante, notes that in Spain, sparse genomics resources have been almost exclusively devo
Genetic secrets of good wine
Xavier Bosch
Genome Biology , 2003, DOI: 10.1186/gb-spotlight-20040507-01
Abstract: The genetic determinants of grape quality are practically unknown, and how local environmental factors interact at the cellular and molecular levels to cause differences in fruit quality is not understood."Understanding grapevine genomics is now a prerequisite to further improvement of viticultural practices as well as for the development of new varieties through breeding programs and adapting the best clones to the most suitable vineyard environments," José Miguel Martínez-Zapater, the Spanish coordinator of the project at Madrid's National Center of Biotechnology, told us.The grape genomics project, funded by Genome Spain and Genome Canada, is meant to elucidate developmental and metabolic pathways underlying grape development and quality traits and predict how these pathways are modified by microclimate and common viticultural practices as well as by genetic differences among grapevine cultivars.The project, announced last month (April 7) by the University of Navarra, is expected to generate useful tools for genomic analysis, such as full length cDNA libraries."The proposal is highly committed to the development of tools for functional analyses at different organismal levels (i.e., whole plant, organ, and cell), including cell-based assays and whole plants for functional studies as well as detached shoots for greenhouse experiments concerning the environment and berry ripening," notes Martínez-Zapater.Steven Lund, the Canadian coordinator of the project at the University of British Columbia in Vancouver, said that "[this] is a new, exciting project where in more than one way, the Old World meets the New World. Spain, in 'Old World' Europe, is one of the largest grape and wine producers in the world, whereas Canada, in the 'New World,' is one of the very youngest.""Throughout the project," Lund told us, "using complementary areas of expertise, our two countries will together have the opportunity to begin to dissect the traditional practice of viticulture using mod
Picramnia tumbesina: una nueva Picramniaceae, endémica del bosque seco tropical al occidente de Ecuador
Cornejo, Xavier;
Acta Botanica Brasilica , 2006, DOI: 10.1590/S0102-33062006000200011
Abstract: picramnia tumbesina a new dioecious tree, endemic to tropical dry forest in western ecuador is described. it is similar to p. sellowii planch. subsp. sellowii, but differs by having ramiflorous inflorescences, fistulose branches, larger leaflets and leaves, and longer pedicels on the pistillate flowers and fruits.
Corros?o social, pragmatismo e ressentimento: vozes dissonantes no cinema brasileiro de resultados
Xavier, Ismail;
Novos Estudos - CEBRAP , 2006, DOI: 10.1590/S0101-33002006000200010
Abstract: the article analyzes three recent movies from brazilian popular cinema in which the "voice over" plays an important role: cidade de deus, o homem que copiava and redentor. the voice as a discourse of the subject "in situation" is seen against the framework of the social context, characterized by tensions related to violence, growth of illegal markets, business crime; hegemony of consumption and crisis of the family.
La educación en tiempos de globalización: ?quién se beneficia?
Bonal, Xavier;
Educa??o & Sociedade , 2009, DOI: 10.1590/S0101-73302009000300002
Abstract: in the context of economic neoliberalism, educational policies assume positive effects for both economic growth and equality of educational opportunities. in recent years, this thinking has been hegemonic: it has been extended around the world and especially in developing countries (with a special role of the world bank). those policies are presented as a response to the challenges of globalisation and as the correct strategy to ensure collective benefits of educational development, especially for socially disadvantaged groups. this paper identifies the main theses of neoliberal educational policy. the relationship of education and labor market, the connection between educational expansion and public expenditure and educational strategies to combat poverty are explored as some of the fields where neoliberal educational policies are produced. expected effects of educational policy measures are questioned for each of these fields. at the same time, the text provides evidence of results that show that the most disadvantaged groups are not those that can really obtain the main benefits of mainstream educational policies.
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