527 research outputs found
Observational - relation for Sct stars using eclipsing binaries and space photometry
Delta Scuti ( Sct) stars are intermediate-mass pulsators, whose
intrinsic oscillations have been studied for decades. However, modelling their
pulsations remains a real theoretical challenge, thereby even hampering the
precise determination of global stellar parameters. In this work, we used space
photometry observations of eclipsing binaries with a Sct component to
obtain reliable physical parameters and oscillation frequencies. Using that
information, we derived an observational scaling relation between the stellar
mean density and a frequency pattern in the oscillation spectrum. This pattern
is analogous to the solar-like large separation but in the low order regime. We
also show that this relation is independent of the rotation rate. These
findings open the possibility of accurately characterizing this type of
pulsator and validate the frequency pattern as a new observable for
Sct stars.Comment: 11 pages, including 2 pages of appendix, 2 figures, 2 tables,
accepted for publication in ApJ
Impact of Carvedilol on the Mitochondrial Damage Induced by Hypoxanthine and Xantine Oxidase - What Role in Myocardial Ischemia and Reperfusion?
Objectivo: Os efeitos cardioprotectores do
carvedilol (CV) poderão ser explicados, em
parte, por interacções ao nível da
mitocôndria cardíaca. O objectivo deste
trabalho visou o estudo do efeito protector do
CV em mitocôndrias cardíacas durante danos
oxidativos induzidos por hipoxantina e
xantina oxidase (HX/XO), uma conhecida
fonte de estresse oxidativo no sistema
cardiovascular.
Métodos: As mitocôndrias foram isoladas a
partir de corações de ratos Wistar (n=8) e
incubadas com o par HX/XO, na presença e
na ausência de cálcio. Vários métodos foram
utilizados de modo a verificar a acção
protectora do CV: avaliação das alterações de
volume mitocondrial (variação da densidade
óptica da suspensão mitocondrial), tomada e
libertação de cálcio mitocondrial (com uma
sonda fluorescente, Calcium Green-5N) e
respiração mitocondrial (com um eléctrodo
de oxigénio).
Resultados: O CV reduziu os danos
mitocondriais associados à produção de
espécies reactivas de oxigénio (ERO) pelos
prooxidantes, como verificado pela redução
no entumescimento mitocondrial e aumento
da capacidade de retenção do cálcio pela
mitocôndria. O CV melhorou ainda a
capacidade respiratória mitocondrial associada ao estado fosforilativo e aumentou
o índice de controlo respiratório (p<0.05) e o
quociente ADP/O (p<0.001) das
mitocôndrias cardíacas sob estresse oxidativo
induzido por HX/XO.
Conclusões: Os dados indicam que o CV
protegeu parcialmente a mitocôndria
cardíaca de danos oxidativos induzidos por
HX/XO, o que poderá ser de grande
utilidade em situações de isquémiareperfusão
do miocárdio.
Os resultados também sugerem que a
mitocôndria poderá ser um alvo prioritário
para a acção benéfica de alguns fármacos
cardioprotectores.Objectives: The cardioprotective effects of
carvedilol (CV) may be explained in part by
interactions with heart mitochondria. The
objective of this work was to study the
protection afforded by CV against oxidative
stress induced in isolated heart mitochondria
by hypoxanthine and xanthine oxidase
(HX/XO), a well-known source of reactive
oxygen species (ROS) in the cardiovascular
system.
Methods: Mitochondria were isolated from
Wistar rat hearts (n=8) and incubated with
HX/XO in the presence and in the absence of
calcium. Several methods were used to assess
the protection afforded by CV: evaluation of
mitochondrial volume changes (by measuring
changes in the optical density of the
mitochondrial suspension), calcium uptake
and release (with a fluorescent probe, Calcium
Green 5-N) and mitochondrial respiration
(with a Clark-type oxygen electrode).
Results: CV decreased mitochondrial damage
associated with ROS production by HX and
XO, as verified by the reduction of mitochondrial swelling and increase in
mitochondrial calcium uptake. In the
presence of HX and XO, CV also
ameliorated mitochondrial respiration in the
active phosphorylation state and prevented
decrease in the respiratory control ratio
(p<0.05) and in mitochondrial
phosphorylative efficiency (p<0.001).
Conclusions: The data indicate that CV
partly protected heart mitochondria from
oxidative damage induced by HX and XO,
which may be useful during myocardial
ischemia and reperfusion. It is also
suggested that mitochondria may be a
priority target for the protective action of
some compounds
Carvedilol: Relation Between Antioxidant Activity and Inhibition of the Mitochondrial Permeability Transition
Objectivos: A transição de permeabilidade
mitocondrial (TPM) é um evento associado a
estresse oxidativo severo (por exemplo,
durante isquémia e reperfusão do miocárdio)
e acumulação excessiva de cálcio
mitocondrial, podendo mesmo levar a morte
celular. Neste estudo comparou-se o efeito
do Carvedilol (CV) na TPM cardíaca
induzida por cálcio/fosfato (Ca/Pi) e
cálcio/carboxiatractilato (Ca/Catr). Para a
indução da TPM por Ca/Pi, o estresse
oxidativo tem um papel importante, levando
a oxidação de grupos tiólicos proteicos
mitocondriais, em contraste com o efeito do
Ca/Catr, onde essa oxidação é secundária à
indução da TPM e não é motivada por
estresse oxidativo.
Materiais e métodos: As mitocôndrias foram
isoladas a partir do coração de rato e
avaliaram-se parâmetros relacionados com a
indução da TPM (n=5 para cada indutor):
entumescimento mitocondrial e oxidação dos
grupos tiólicos proteicos (ambos por
espectrofotometria).
Resultados: Com Ca/Pi, o CV protegeu a
mitocôndria da indução da TPM,
nomeadamente na sua forma deletéria de alta
condutância. Este efeito evidenciou-se pela
diminuição do entumescimento mitocondrial.
Este efeito foi simultâneo com a inibição da
oxidação dos grupos tiólicos proteicos carmitocondriais
(p<0.001). O CV não mostrou
efeitos protectores com Ca/Catr.
Conclusões: O CV protegeu a mitocôndria
cardíaca da TPM, mas apenas quando a
oxidação dos grupos tiólicos proteicos foi
causa e não consequência da TPM. Estes
resultados mostram claramente que, durante
agressões ao miocárdio (durante a
isquémia/reperfusão, por exemplo), o efeito
protector do CV é primariamente devido a
um efeito antioxidante, inibindo a produção
e os efeitos das espécies reactivas de
oxigénio.Objectives: The mitochondrial permeability
transition (MPT) is an event related to severe
oxidative stress (for example, during
myocardial ischemia and reperfusion) and
excessive mitochondrial calcium
accumulation, also being implicated in cell
death. In this study, we compared the effect
of carvedilol on the cardiac MPT induced by
calcium and phosphate (Ca/Pi) and
calcium/carboxyatractyloside (Ca/Catr).
Oxidative stress plays a major role in MPT
induction by Ca/Pi, leading to the oxidation
of protein thiol groups, in contrast with
Ca/Catr, where such oxidation is secondary
to MPT induction and is not caused by
oxidative stress.
Materials and methods: Mitochondria were
isolated from rat hearts and parameters
related to MPT induction were evaluated
(n=5 for each inducer): mitochondrial
swelling and oxidation of protein thiol groups
(both measured by spectrophotometry).
Results: Using Ca/Pi, carvedilol protected
mitochondria from MPT induction,
particularly in its high conductance form. Its
effect was demonstrated by analyzing the
decrease in mitochondrial swelling
amplitude. Simultaneously, we observed inhibition of protein thiol group oxidation
(p<0.001). By contrast, carvedilol did not
show any protective effect with Ca/Catr.
Conclusions: Carvedilol was only effective
against the MPT when the oxidation of
protein thiol groups was the cause and not
the consequence of the MPT phenomenon.
The results clearly show that during
myocardial aggressions (ischemia and
reperfusion, for example), the protective
effect of carvedilol is primarily due to an
antioxidant mechanism, inhibiting the
production and effects of reactive oxygen
species
Estimativa da prevalência de déficit de altura/idade a partir da prevalência de déficit de peso/idade em crianças brasileiras
INTRODUCTION: Anthropometry is frequently used for evaluating nutritional status of individuals and populations. In recent years, community surveys have been conducted by health professionals in various regions of Brazil with the objective of complementing the data obtained through nutritional surveillance programs. One important difficulty in conducting these assessments has been measuring height during visits to the homes of survey participants. METHODS: Thirty-eight anthropometric surveys of Brazilian children aged up to 5 years using the National Center for Health Statistics (NCHS) reference were identified. The percentage of children with a Z-score below standard deviations was used to define deficits of weight for age and height for age. RESULTS: Correlation between prevalences of height for age and weight for age deficits were examined. Due to the low prevalence of deficits in weight for height in all surveys, there was a strong correlation between weight for age and height for age at the population level. Approximately 90% of the height for age (H/A) variation was accounted for by that of weight for age (W/A). CONCLUSIONS: Using the equation, (Prevalence H/A) = 0.74 + 2.34 (Prevalence W/A) - 0.03 (Prevalence W/A)² it is possible to estimate the prevalence of height deficits on the basis of prevalence of weight deficits. These results suggest that anthropometric surveys as conducted in Brazil, in the context of health services, can be simplified by measuring weight only, instead of both weight and height.INTRODUÇÃO: A antropometria é amplamente utilizada para avaliação nutricional de indivíduos e de grupos populacionais. Em anos recentes, diagnósticos comunitários têm sido realizados por profissionais dos serviços de saúde em diversas regiões brasileiras, com o objetivo de complementar os dados obtidos através de vigilância nutricional. Um obstáculo importante à realização destes diagnósticos é a difícil mensuração da altura em inquéritos domiciliares. MÉTODO: Foram identificados 38 inquéritos antropométricos com crianças de 0 a 5 anos de idade, realizados no Brasil, que utilizaram o padrão de referência NCHS e o percentual de crianças abaixo de -2 escore Z para definição da prevalência de déficit de peso/idade e altura/idade. A análise foi realizada a partir das correlações entre as prevalências de déficits de altura/idade e peso/idade definidas. RESULTADOS: A análise mostrou que devido à baixa prevalência de déficits de peso/altura há forte correlação entre peso/idade e altura/idade, em nível populacional. Cerca de 90% da variabilidade de altura/idade (A/I) é explicada pelo peso/idade (P/I). CONCLUSÃO: Através da equação (Prev. A/I) = 0,74 + 2,34 (Prev. P/I) - 0,03 (Prev. P/I)2, é possível estimar os déficits de altura, desde que se conheça os déficits de peso. Espera-se que os resultados possam contribuir para a simplificação dos inquéritos antropométricos realizados no âmbito dos serviços e favorecer sua disseminação
β-Lactam antibiotics and vancomycin inhibit the growth of planktonic and biofilm Candida spp.: An additional benefit of antibiotic-lock therapy?
AbstractThe aim of this study was to evaluate the effects of cefepime, meropenem, piperacillin/tazobactam (TZP) and vancomycin on strains of Candida albicans and Candida tropicalis in planktonic and biofilm forms. Twenty azole-derivative-resistant strains of C. albicans (n=10) and C. tropicalis (n=10) were tested. The susceptibility of planktonic Candida spp. to the antibacterial agents was investigated by broth microdilution. The XTT reduction assay was performed to evaluate the viability of growing and mature biofilms following exposure to these drugs. Minimum inhibitory concentrations (MICs) ranged from 0.5mg/mL to 2mg/mL for cefepime, TZP and vancomycin and from 0.5mg/mL to 1mg/mL for meropenem and the drugs also caused statistically significant reductions in biofilm cellular activity both in growing and mature biofilm. Since all of the tested drugs are commonly used in patients with hospital-acquired infections and in those with catheter-related infections under antibiotic-lock therapy, it may be possible to obtain an additional benefit from antibiotic-lock therapy with these drugs, namely the control of Candida biofilm formation
Optoelectronic simulations for novel light management concepts in Cu(In,Ga)Se2 solar cells
One of the trends making its way through the Photovoltaics (PV) industry, is the search for new application possibilities. Cu(In,Ga)Se2 (CIGS) thin film solar cells stand out due to their class leading power conversion efficiency of 23.35 %, flexibility, and low cost. The use of sub-μm ultrathin CIGS solar cells has been gaining prevalence, due to the reduction in material consumption and the manufacturing time. Precise CIGS finite-difference time-domain (FDTD) and 3D-drift diffusion baseline models were developed for the Lumerical suite and a 1D electrical model for SCAPS, allowing for an accurate description of the optoelectronic behavior and response of thin and ultrathin CIGS solar cells. As a result, it was possible to obtain accurate descriptions of the optoelectronic behavior of thin and ultrathin solar cells, and to perform an optical study and optimization of novel light management approaches, such as, random texturization, photonic nanostructures, plasmonic nanoparticles, among others. The developed light management architectures enabled to push the optical performance of an ultrathin solar cell and even surpass the performance of a thin film solar cell, enabling a short-circuit current enhancement of 6.15 mA/cm2 over an ultrathin reference device, without any light management integrated.publishe
Classification of the Mediterranean lowland to submontane pine forest vegetation
Vegetation SurveyAim: Vegetation types of Mediterranean thermophilous pine forests dominated by
Pinus brutia, Pinus halepensis, Pinus pinaster and Pinus pinea were studied in various
areas. However, a comprehensive formal vegetation classification of these forests
based on a detailed data analysis has never been developed. Our aim is to provide
the first broad-scale classification of these pine forests based on a large data set of
vegetation plots.
Location: Southern Europe, North Africa, Levant, Anatolia, Crimea and the Caucasus.
Methods: We prepared a data set of European and Mediterranean pine forest vegetation
plots. We selected 7,277 plots dominated by the cold-sensitive Mediterranean
pine species Pinus brutia, Pinus halepensis, Pinus pinaster and Pinus pinea. We classified
these plots using TWINSPAN, interpreted the ecologically and biogeographically
homogeneous TWINSPAN clusters as alliances, and developed an expert system for
automatic vegetation classification at the class, order and alliance levels.
Results: We described Pinetea halepensis as a new class for the Mediterranean lowland
to submontane pine forests, included in the existing Pinetalia halepensis order,
and distinguished 12 alliances of native thermophilous pine forests, including four
newly described and three informal groups merging supposedly native stands and
old-established plantations. The main gradients in species composition reflect elevational
vegetation belts and the west–east, and partly north–south, biogeographical
differences. Both temperature and precipitation seasonality co-vary with these
gradients.
Conclusions: We provide the first formal classification at the order and alliance levels
for all the Mediterranean thermophilous pine forests based on vegetation-plot data.
This classification includes traditional syntaxa, which have been critically revised,
and a new class and four new alliances. We also outline a methodological workflow that might be useful for other vegetation classification syntheses. The expert system,
which is jointly based on pine dominance and species composition, is a tool for applying
this classification in research and nature conservation survey, monitoring and
managementinfo:eu-repo/semantics/publishedVersio
Environmental Costs of Government-Sponsored Agrarian Settlements in Brazilian Amazonia
Brazil has presided over the most comprehensive agrarian reform frontier colonization program on Earth, in which ~1.2 million settlers have been translocated by successive governments since the 1970's, mostly into forested hinterlands of Brazilian Amazonia. These settlements encompass 5.3% of this ~5 million km2 region, but have contributed with 13.5% of all land conversion into agropastoral land uses. The Brazilian Federal Agrarian Agency (INCRA) has repeatedly claimed that deforestation in these areas largely predates the sanctioned arrival of new settlers. Here, we quantify rates of natural vegetation conversion across 1911 agrarian settlements allocated to 568 Amazonian counties and compare fire incidence and deforestation rates before and after the official occupation of settlements by migrant farmers. The timing and spatial distribution of deforestation and fires in our analysis provides irrefutable chronological and spatially explicit evidence of agropastoral conversion both inside and immediately outside agrarian settlements over the last decade. Deforestation rates are strongly related to local human population density and road access to regional markets. Agrarian settlements consistently accelerated rates of deforestation and fires, compared to neighboring areas outside settlements, but within the same counties. Relocated smallholders allocated to forest areas undoubtedly operate as pivotal agents of deforestation, and most of the forest clearance occurs in the aftermath of government-induced migration
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