726 research outputs found
A cross-layer scheduling strategy for the downlink of a MIMO-OFDMA system with heterogeneous traffic
in this paper we propose and investigate a cross-layer
multiuser scheduling strategy for the support of heterogeneous traffic in
the downlink of a MIMO-OFDMA system. It jointly considers different
objectives: maximize the sum-rate on the radio channel, ensure a fair
allocation of resources among users belonging to the same traffic class,
consider the dynamics of traffic sources by looking at the delay of
data packets in the queues, contribute to maximize quality of service
figures at the application level. To exploit temporal diversity and to
reduce complexity, the ergodic weighted sum-rate is maximized and dual
optimization with stochastic approximation is applied to derive on-line
algorithms. The numerical results show the capability of the scheduler
to allocate physical layer resources according to rate constraints imposed
for each different traffic class and with fairness inside each class, even
in presence of different channels conditions and different network loads.Postprint (published version
Critical Behavior of Disordered Systems with a Free Surface
The behavior of homogeneous and disordered systems with a free boundary is
described on the basis of group theory in the two-loop approximation directly
in three-dimensional space. The effect of the free boundary on the regime of
the bulk critical behavior is revealed. It is shown that the boundedness of the
system slightly affects the regime of the bulk critical behavior in the case of
the ordinary transition, whereas this effect is more noticeable in the case of
the special transition. Surface critical phenomena are described for
homogeneous and disordered systems, and the critical exponents are calculated
in the two-loop approximation. It is shown that the effect of impurities is
insignificant in the special phase transition, whereas it is more noticeable in
the ordinary phase transition. The derived critical exponents are compared with
the computer-simulation results.Comment: 19 pages, 2 figure
Genetic analysis of porcine circovirus type 2 from pigs affected with PMWS in Chile reveals intergenotypic recombination
Background: Porcine circovirus type 2 (PCV2) is a very small, non-enveloped and icosahedral virus, with circular single stranded DNA genome. This virus is the most ubiquitous and persistent pathogen currently affecting the swine industry worldwide. PCV2 has been implicated as the major causative agent of postweaning multisystemic wasting syndrome (PMWS), a disease which is characterized by severe immunosuppressive effects in the porcine host. Worldwide PCV2 isolates have been classified into four different genotypes, PCV2a, PCV2b, PCV2c and PCVd. The goal of this work was to conduct the first phylogenetic analysis of PCV2 in Chile. Methods: PCV2 partial ORF2 sequences (462 nt) obtained from 29 clinical cases of PMWS in 22 Chilean intensive swine farms, covering over the 90% of the local pork-production, were analyzed. Results: 14% and 52% of sequences belonged to the genotypes PCV2a and PCV2b, respectively. Surprisingly, 34% of sequences were PCV2a/PCV2d recombinant viruses. Conclusions: Our findings suggested that a novel cluster of Chilean sequences emerged resulting from intergenotypic recombination between PCV2a and PCV2d
First report of porcine respirovirus 1 in South America.
Porcine respirovirus 1 (PRV1) is an emerging virus in pigs that has been previously described in the USA and China. There are no reports of its presence in the rest of the world. The objective of this study was to determine the occurrence of PRV1 in Chile and to determine its phylogeny. Thus, we collected samples (oral fluids, nasal swabs, and lungs) from a swine influenza A virus (IAV) surveillance program, most of which belonged to pigs with respiratory disease. The samples were analyzed by RT-PCR, and the viral sequencing was obtained using RNA whole-genome sequencing approach. Maximum likelihood phylogeny was constructed with the available references. Thirty-one of 164 samples (18.9 %) were RT-PCR positive for PRV1: 62.5 % oral fluids, 19.0 % nasal swabs, and 8.6 % lungs. All 6 farms in this study had at least one positive sample, with 6-40 % of positive results per farm, which suggests that PRV1 is disseminated in Chilean swine farms. Twenty-one of 31 (677%) PRV1-positive samples were also positive for IAV, so the role of PRV1 as secondary pathogen in respiratory disease needs to be further evaluated. Near to complete genome of two PRV1s were obtained from two farms. The phylogenies, in general, showed low bootstrap support, except the concatenated genome and the L gene trees which showed clustering of the Chilean PRV1 with Asian sequences, suggesting a close genetic relationship. This is the first report of PRV1 in the Southern Hemisphere. Further studies are necessary to determine the genetic diversity of this virus in Chile
Synthesis, antimalarial activity, structure–activity relationship analysis of thieno-[3,2-b]benzothiazine S,S-dioxide analogs
An improved procedure for the synthesis of 3-amino-9-arylsubstituted-thieno[3,2-b]benzothiazine S,S-dioxide 2-decarboxylated is reported. Thieno-[3,2-b]benzothiazine S,S-dioxide derivatives were investigated for their abilities to inhibit β-hematin formation, hemoglobin hydrolysis and in vivo for their efficacy in rodent Plasmodium berghei. Compounds 5j-o were the most promising as inhibitors of hemoglobin hydrolysis, however, the compounds are not as efficient as chloroquine. A structure-activity relationship (SAR) study was carried out in this series. Our results allow us to determine the minimal structural requirements to produce the biological response.Fil: Barazarte, Arthur. Universidad Central de Venezuela; VenezuelaFil: Camacho, José. Universidad Central de Venezuela; VenezuelaFil: Domínguez, José. Universidad Central de Venezuela; VenezuelaFil: Lobo, Gricela. Universidad Central de Venezuela; VenezuelaFil: Gamboa, Neira. Universidad Central de Venezuela; VenezuelaFil: Rodrigues, Juan. Universidad Central de Venezuela; VenezuelaFil: Capparelli, Mario V.. Universidad Central de Venezuela; VenezuelaFil: Álvarez Larena, Ángel. Universitat Autònoma de Barcelona; EspañaFil: Andujar, Sebastian Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Charris, Jaime. Universidad Central de Venezuela; Venezuel
Deletion of inducible nitric-oxide synthase in leptin-deficient mice improves brown adipose tissue function
Abstract
Background: Leptin and nitric oxide (NO) on their own participate in the control of non-shivering thermogenesis. However,
the functional interplay between both factors in this process has not been explored so far. Therefore, the aim of the present
study was to analyze the impact of the absence of the inducible NO synthase (iNOS) gene in the regulation of energy
balance in ob/ob mice.
Methods and Findings: Double knockout (DBKO) mice simultaneously lacking the ob and iNOS genes were generated, and
the expression of molecules involved in the control of brown fat cell function was analyzed by real-time PCR, western-blot
and immunohistochemistry. Twelve week-old DBKO mice exhibited reduced body weight (p,0.05), decreased amounts of
total fat pads (p,0.05), lower food efficiency rates (p,0.05) and higher rectal temperature (p,0.05) than ob/ob mice.
Ablation of iNOS also improved the carbohydrate and lipid metabolism of ob/ob mice. DBKO showed a marked reduction in
the size of brown adipocytes compared to ob/ob mutants. In this sense, in comparison to ob/ob mice, DBKO rodents showed
an increase in the expression of PR domain containing 16 (Prdm16), a transcriptional regulator of brown adipogenesis.
Moreover, iNOS deletion enhanced the expression of mitochondria-related proteins, such as peroxisome proliferatoractivated
receptor c coactivator-1 a (Pgc-1a), sirtuin-1 (Sirt-1) and sirtuin-3 (Sirt-3). Accordingly, mitochondrial uncoupling
proteins 1 and 3 (Ucp-1 and Ucp-3) were upregulated in brown adipose tissue (BAT) of DBKO mice as compared to ob/ob
rodents.
Conclusion: Ablation of iNOS improved the energy balance of ob/ob mice by decreasing food efficiency through an increase
in thermogenesis. These effects may be mediated, in part, through the recovery of the BAT phenotype and brown fat cell
function improvement
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