116 research outputs found
Single-Dose Intravenous Toxicity Study of IRDye 800CW in Sprague-Dawley Rats
Objective: Fluorophore-labeled contrast imaging agents are moving toward clinical use for a number of applications. The near-infrared dye IRDye 800CW is frequently used in its N-hydroxysuccinamide (NHS) ester form for labeling these agents. Following conjugation or breakdown of a labeled ligand, excess NHS ester is converted to the carboxylate form. To prepare for clinical use as a near-infrared fluorophore, a toxicity study was conducted on IRDye 800CW carboxylate. Methods: Male and female Sprague–Dawley rats were given a single intravenous or intradermal administration of IRDye 800CW carboxylate; Indocyanine Green was used as a comparative control. Animals were injected with varying doses of the test and control articles and observed for up to 14 days. Clinical chemistry, hematological, and pharmacokinetic analyses were performed on subgroups of animals. Organs were analyzed for content of the test article. Tissues were analyzed microscopically for pathological changes. Results: Based on hematologic, clinical chemistry, and histopathologic evaluation, single administration of IRDye 800CW carboxylate intravenously at dose levels of 1, 5, and 20 mg/kg or 20 mg/kg intradermally produced no pathological evidence of toxicity. Conclusion: A dose of 20 mg/kg was identified as the no observed adverse effect level following IV or ID routes of administration of IRDye 800CW
Global Fractional Analytic Perturbation Theory in QCD with Selected Applications
We give the generalization of Fractional Analytic Perturbation Theory (FAPT)
for QCD observables, recently developed both for the Euclidean and Minkowski
regions of squared momentum transfer q^2, which takes into account heavy-quark
thresholds. The original analytic approach to QCD, initiated by Jones,
Solovtsov and Shirkov, is shortly summarized. We also shortly consider the
basic aspects of FAPT and then concentrate on the accounting for the
heavy-quark thresholds problem and the construction of global version of FAPT.
We discuss what one should use as an analytic coupling in the timelike region
q^2=s>0 for the e^{+}e^{-}-annihilation and the pion form factor, and consider
applications to phenomenologically relevant processes (the factorizable part of
the pion form factor and the Higgs boson decay into a b\bar{b} pair), as well
as to the summation of perturbative series.Comment: 63 pages, 15 figures, in russian (first part of Doktor-Nauk thesis),
published in Physics of Particles and Nuclei, typos corrected (English
version avalable on request); corrected formulas (3.14b)-(3.14c) and (B9b
ATHENA detector proposal - a totally hermetic electron nucleus apparatus proposed for IP6 at the Electron-Ion Collider
ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity.This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges
Os dividendos como estratégia de investimentos em ações
Na Teoria de Finanças, o papel dos dividendos nas cotações é um tema controverso, uma vez que há diferentes teorias que abordam sua relevância para o valor das ações e, em conseqüência, para a riqueza dos acionistas. Além disso, as descobertas empíricas que originaram a Hipótese de Mercado Eficiente de Capitais (HME) não apenas contradizem a Análise Técnica, mas também impõem um desafio à declarada habilidade superior da Análise Fundamentalista em gerar retornos superiores, com base em fatores ou variáveis contábeis, financeiros e econômicos, tais como o dividend yield (retorno em dividendos). A fim de se verificar a relação entre dividend yields e as taxas de retornos das ações, bem como a viabilidade de uma estratégia baseada em dividend yields históricos de "bater" o mercado, foram construídas, mensalmente, durante o período que vai do Plano Real em julho de 1994 a dezembro de 1999, três diferentes carteiras (alto, baixo e zero). Seus riscos, retornos e indicadores de desempenho ajustados ao risco foram calculados e comparados entre si e com seu paradigma (benchmark), o Índice da Bolsa de Valores de São Paulo - Ibovespa. A evidência empírica é incapaz de sugerir que as ações de altos dividend yield tendem a possuir maiores ou menores taxas de retorno do que as ações de baixo ou zero yield. Ademais, as evidências sugerem que não é possível demonstrar, usando o método empírico aplicado, uma clara associação entre dividend yield e taxas de retorno das ações.In Finance Theory, the role of dividends in stock prices is a controversial issue, considering the different theories that exist on their relevance for stock value and, consequently, for shareholders' wealth. Furthermore, empirical findings that have originated the Efficient Market Hypothesis (EMH) not only contradict Technical Analysis, but also pose a challenge to the Fundamental Analysis' supposedly superior ability to generate higher returns based on accounting, financial and economic factors or variables such as the dividend yield. In order to assess the relationship between dividend yields and stocks returns as well as the viability of a strategy based on historic dividend yield to "beat" the market, with reference to the period from the beginning of the Real Plan in July 1994 until December 1999, three different yield portfolios (high, low and zero) were formed on a monthly basis.Their risks, returns and risk-adjusted portfolio performance measurements were calculated, and then compared both among themselves and to the benchmark (São Paulo Stock Exchange Index - Ibovespa). Empirical evidence is unable to suggest either that stocks with a high dividend yield tend to have higher or lower returns than those with a low or zero yield. Moreover, the evidences suggest that, using the applied empirical method, no clear association between dividend yield and stock returns can be demonstrated
Consistent patterns of common species across tropical tree communities
Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Global variation in diabetes diagnosis and prevalence based on fasting glucose and hemoglobin A1c
Fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) are both used to diagnose diabetes, but these measurements can identify different people as having diabetes. We used data from 117 population-based studies and quantified, in different world regions, the prevalence of diagnosed diabetes, and whether those who were previously undiagnosed and detected as having diabetes in survey screening, had elevated FPG, HbA1c or both. We developed prediction equations for estimating the probability that a person without previously diagnosed diabetes, and at a specific level of FPG, had elevated HbA1c, and vice versa. The age-standardized proportion of diabetes that was previously undiagnosed and detected in survey screening ranged from 30% in the high-income western region to 66% in south Asia. Among those with screen-detected diabetes with either test, the age-standardized proportion who had elevated levels of both FPG and HbA1c was 29-39% across regions; the remainder had discordant elevation of FPG or HbA1c. In most low- and middle-income regions, isolated elevated HbA1c was more common than isolated elevated FPG. In these regions, the use of FPG alone may delay diabetes diagnosis and underestimate diabetes prevalence. Our prediction equations help allocate finite resources for measuring HbA1c to reduce the global shortfall in diabetes diagnosis and surveillance
Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults
Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We
estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from
1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories.
Methods We used data from 3663 population-based studies with 222 million participants that measured height and
weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate
trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children
and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the
individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For schoolaged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference)
and obesity (BMI >2 SD above the median).
Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in
11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed
changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and
140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of
underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and
countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior
probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse
was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of
thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a
posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%)
with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and
obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for
both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such
as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged
children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls
in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and
42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents,
the increases in double burden were driven by increases in obesity, and decreases in double burden by declining
underweight or thinness.
Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an
increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy
nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of
underweight while curbing and reversing the increase in obesit
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