1,250 research outputs found
Gerador de Faltas para Aplicações em Transformadores
Transformers are the most important electrical device used in power systems for transmission and distribution of electrical energy. They have a significant impact on the losses of utilities. Although transformers have a long life-cycle, the increasingly industrial consumption result in more severe operating conditions, including fault conditions, reducing its efficiency and therefor its life-cycle. In this work a fault generator power supply is proposed to be used in transformer`s fault tests
From Fundamental Strings to Small Black Holes
We give evidence in favour of a string/black hole transition in the case of
BPS fundamental string states of the Heterotic string. Our analysis goes beyond
the counting of degrees of freedom and considers the evolution of dynamical
quantities in the process. As the coupling increases, the string states
decrease their size up to the string scale when a small black hole is formed.
We compute the absorption cross section for several fields in both the black
hole and the perturbative string phases. At zero frequency, these cross
sections can be seen as order parameters for the transition. In particular, for
the scalars fixed at the horizon the cross section evolves to zero when the
black hole is formed.Comment: 36 pages, 4 figures, argument about minimally coupled scalar
absorption cross section clarifie
CaracterÃsticas dos serviços de saúde associadas à adesão ao tratamento da tuberculose
OBJECTIVE: To analyze characteristics related to adherence to tuberculosis treatment in tuberculosis outpatient clinics. METHODS: An ecological study was conducted in outpatient clinics for the treatment of tuberculosis cases in the sanitary districts of Salvador, Northeastern Brazil, in 2006. The sample was composed of the municipal health units that assisted 67.2% of the 2,283 tuberculosis cases that were reported during the year. The following variables were analyzed: cure, dropout, tests, health team and benefits offered to the patients. Chi-square test or Fisher's exact test was used to verify the association between variables, and associations with pOBJETIVO: Analisar caracterÃsticas relacionadas à adesão ao tratamento dos casos de tuberculose em serviços de referência para tuberculose. MÉTODOS: Trata-se de um estudo ecológico nas unidades de referência no tratamento dos casos de tuberculose dos distritos sanitários de Salvador, BA, em 2006. A amostra foi composta pelas unidades de saúde municipais que atenderam 67,2% dos 2.283 casos notificados de tuberculose no ano. Foram analisadas as variáveis: cura, abandono, exames realizados, equipe de saúde e benefÃcios aos pacientes. Para verificar associação entre as variáveis, foi utilizado o teste qui-quadrado ou exato de Fisher, sendo consideradas estatisticamente significantes as associações com pOBJETIVO: Analizar caracterÃsticas relacionadas a la adhesión al tratamiento de los casos de tuberculosis en servicios de referencia para tuberculosis. MÉTODOS: Se trata de estudio ecológico en las unidades de referencia en el tratamiento de los casos de tuberculosis de los distritos sanitarios de Salvador, Noreste de Brasil, en 2006. La muestra fue compuesta por las unidades de salud municipales que atendieron 67,2% de los 2.283 casos notificados de tuberculosis en el año. Fueron analizadas las variables: cura, abandono, exámenes realizados, equipo de salud y beneficios a los pacientes. Para verificar asociación entre las variables, fue utilizada la prueba chi-cuadrado o exacto de Fisher, siendo consideradas estadÃsticamente significativas las asociaciones con
Application of Dielectric Barrier Discharge (DBD) atmospheric pressure plasma for pretreatment of medical textiles
Conventional pretreatment by wet chemistry
and/or low-pressure plasma have several drawbacks [1]. Atmospheric plasma is an alternative
and cost-competitive method to low-pressure
plasma and wet chemical pretreatments, allowing continuous and uniform processing of fibers,
substrates and films surfaces, improving its
functionalization performance [2]. This technology has been studied in the field of the R&D
project - PLASMAMED. The main objective of
this project is to produce a new generation of
coatings containing nanoparticles (NPs) and
enzybiotics, with controllable antibacterial activity, on medical textiles, with special emphasis
in antimicrobial dressing for pressure injury and
hernia meshes. To achieve this goal, a dielectric
barrier discharge (DBD) atmospheric pressure
plasma was used as a pretreatment sustainable
alternative.
In this sense, medical-grade 100% polyester
(PES) fabrics were pretreated by atmospheric
plasma technology, where various processing
conditions were tested. Different treatment
speeds and discharges powers were tested, as
well as the application of various gases (such as
helium, oxygen and nitrogen) and a corona
treatment (air), with a carrier gas (argon). The
characterization of these pretreated textiles was
carried out by contact angle (CA), through the
sessile drop technique, with 3 µL water droplets
on the surface of the textile. In general, contact
angles exhibit a significant decrease (between
40º and 60º for all studied gases), when compared with the standard values for substrate
without treatment (around 120º). Therefore,
plasma pretreatment significantly improved the
hydrophilicity of these fabrics (Figure 1), which
reveals to be an advantage for the further functionalization step
Clinical evaluation, biochemistry and genetic polymorphism analysis for the diagnosis of lactose intolerance in a population from northeastern Brazil
OBJECTIVE: This work aimed to evaluate and correlate symptoms, biochemical blood test results and single nucleotide polymorphisms for lactose intolerance diagnosis. METHOD: A cross-sectional study was conducted in Fortaleza, Ceará, Brazil, with a total of 119 patients, 54 of whom were lactose intolerant. Clinical evaluation and biochemical blood tests were conducted after lactose ingestion and blood samples were collected for genotyping evaluation. In particular, the single nucleotide polymorphisms C>;T-13910 and G>;A-22018 were analyzed by restriction fragment length polymorphism/polymerase chain reaction and validated by DNA sequencing. RESULTS: Lactose-intolerant patients presented with more symptoms of flatulence (81.4%), bloating (68.5%), borborygmus (59.3%) and diarrhea (46.3%) compared with non-lactose-intolerant patients (
Genetic manipulation of cell line derived reticulocytes enables dissection of host malaria invasion requirements
Investigating the role that host erythrocyte proteins play in malaria infection is hampered by the genetic intractability of this anucleate cell. Here we report that reticulocytes derived through in vitro differentiation of an enucleation-competent immortalized erythroblast cell line (BEL-A) support both successful invasion and intracellular development of the malaria parasite Plasmodium falciparum. Using CRISPR-mediated gene knockout and subsequent complementation, we validate an essential role for the erythrocyte receptor basigin in P. falciparum invasion and demonstrate rescue of invasive susceptibility by receptor re-expression. Successful invasion of reticulocytes complemented with a truncated mutant excludes a functional role for the basigin cytoplasmic domain during invasion. Contrastingly, knockout of cyclophilin B, reported to participate in invasion and interact with basigin, did not impact invasive susceptibility of reticulocytes. These data establish the use of reticulocytes derived from immortalized erythroblasts as a powerful model system to explore hypotheses regarding host receptor requirements for P. falciparum invasion
Genetic manipulation of cell line derived reticulocytes enables dissection of host malaria invasion requirements
Investigatingthe role host erythrocyteproteins play in malaria infection is hampered by the genetic intractability of this anucleate cell. Here we report that reticulocytes derived through in vitro differentiation of an enucleation-competent immortalized erythroblast cell line (BEL-A) support both successful invasion and intracellular development of the malaria parasite Plasmodium falciparum. Using CRISPR-mediated gene knockout and subsequent complementation, we validate an essential role for the erythrocyte receptor basigin in P. falciparum invasion and, for the first time, demonstrate rescueby receptor re-expression.Successful invasion of reticulocytes complemented with a truncated mutant excludes a functional role for the basigincytoplasmic domain during invasion. Contrastingly, knockout of cyclophilin B, reported to participate in invasion and interact with basigin, did not impactinvasive susceptibility of reticulocytes.These data establish the use of reticulocytes derived from immortalized erythroblasts as a powerful model system to explore hypotheses regarding host receptor requirements for P. falciparum invasion
PIEZO1 gain-of-function mutations delay reticulocyte maturation in hereditary xerocytosis
Dehydrated hereditary stomatocytosis 1 or hereditary xerocytosis (HX, OMIM 194380) is a rare hereditary autosomal dominant disorder characterized by hemolytic anemia and red blood cell (RBC) dehydration. The occurrence of HX is linked with gain-of-function mutations in PIEZO1, the gene encoding for the mechanosensitive non-specific cation channel PIEZO121 which is activated by shear-stress and in concert with other ion channels (particularly the Gardos potassium calcium-activated channel, KCNN4) regulates cell volume homeostasis and metabolic activity in the RBC.3 Intriguingly, PIEZO1 gain-of-function mutations have recently been reported to occur at a much higher frequency within the population than had been previously described and have also been implicated in malaria resistance,4 suggesting that the mechanisms underpinning HX may merit further investigation. Since reticulocytosis is one of the hallmarks of HX,5 we sought to determine whether altered reticulocyte maturation could be a causative agent of this phenotype. We characterize reticulocytes and erythrocytes from 10 HX patients in comparison to healthy controls, revealing alterations in deformability and vesicle content that implicate a maturational defect in HX. We further demonstrate that HX patients suffer from impaired reticulocyte maturation as assayed through differences in the extent and rate of loss of CD71 and RNA content over time and that this effect can be recapitulated in healthy reticulocytes upon chemically-induced PIEZO1 overactivation, providing a functional link to the reticulocytosis phenotype present in HX
Reticulocyte and red blood cell deformation triggers specific phosphorylation events
The capacity to undergo substantial deformation is a defining characteristic of the red blood cell (RBC), facilitating transit through the splenic interendothelial slits and microvasculature. Establishment of this remarkable property occurs during a process of reticulocyte maturation that begins with egress through micron-wide pores in the bone marrow and is completed within the circulation. The requirement to undertake repeated cycles of deformation necessitates that both reticulocytes and erythrocytes regulate membrane-cytoskeletal protein interactions in order to maintain cellular stability. In the absence of transcriptional activity, modulation of these interactions in RBCs is likely to be achieved primarily through specific protein posttranslational modifications, which at present remain undefined. In this study, we use high-throughput methods to define the processes that underlie the response to deformation and shear stress in both reticulocytes and erythrocytes. Through combination of a bead-basedmicrosphiltration assay with phosphoproteomics we describe posttranslational modification of RBC proteins associated with deformation. Using microsphiltration and microfluidic biochip-based assays, we explore the effect of inhibiting kinases identified using this dataset. We demonstrate roles for GSK3 and Lyn in capillary transit and maintenance of membrane stability following deformation and show that combined inhibition of these kinases significantly decreases reticulocyte capacity to undergo repeated deformation. Finally, we derive a comprehensive and integrative phosphoproteomic dataset that provides a valuable resource for further mechanistic dissection of the molecular pathways that underlie the RBC's response to mechanical stimuli and for the study of reticulocyte maturation
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