162 research outputs found
Numerically generated quasi-equilibrium orbits of black holes: Circular or eccentric?
We make a comparison between results from numerically generated,
quasi-equilibrium configurations of compact binary systems of black holes in
close orbits, and results from the post-Newtonian approximation. The
post-Newtonian results are accurate through third PN order (O(v/c)^6 beyond
Newtonian gravity), and include rotational and spin-orbit effects, but are
generalized to permit orbits of non-zero eccentricity. Both treatments ignore
gravitational radiation reaction. The energy E and angular momentum J of a
given configuration are compared between the two methods as a function of the
orbital angular frequency \Omega. For small \Omega, corresponding to orbital
separations a factor of two larger than that of the innermost stable orbit, we
find that, if the orbit is permitted to be slightly eccentric, with e ranging
from \approx 0.03 to \approx 0.05, and with the two objects initially located
at the orbital apocenter (maximum separation), our PN formulae give much better
fits to the numerically generated data than do any circular-orbit PN methods,
including various ``effective one-body'' resummation techniques. We speculate
that the approximations made in solving the initial value equations of general
relativity numerically may introduce a spurious eccentricity into the orbits.Comment: 6 pages, 4 figures, to be submitted to Phys. Rev.
SARS-CoV-2: Immune Response Elicited by Infection and Development of Vaccines and Treatments
IndexaciĂłn ScopusThe World Health Organization (WHO) announced in March a pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This new infectious disease was named Coronavirus Disease 19 (COVID-19), and at October 2020, more than 39,000,000 cases of SARS-CoV-2 have been detected worldwide leading to near 1,100,000 deaths. Clinically, COVID-19 is characterized by clinical manifestations, such as fever, dry cough, headache, and in more severe cases, respiratory distress. Moreover, neurological-, cardiac-, and renal-related symptoms have also been described. Clinical evidence suggests that migration of immune cells to the affected organs can produce an exacerbated release of proinflammatory mediators that contribute to disease and render the immune response as a major player during the development of the COVID-19 disease. Due to the current sanitary situation, the development of vaccines is imperative. Up to the date, 42 prototypes are being tested in humans in different clinical stages, with 10 vaccine candidates undergoing evaluation in phase III clinical trials. In the same way, the search for an effective treatment to approach the most severe cases is also in constant advancement. Several potential therapies have been tested since COVID-19 was described, including antivirals, antiparasitic and immune modulators. Recently, clinical trials with hydroxychloroquine—a promising drug in the beginning—were suspended. In addition, the Food and Drug Administration (FDA) approved convalescent serum administration as a treatment for SARS-CoV-2 patients. Moreover, monoclonal antibody therapy is also under development to neutralize the virus and prevent infection. In this article, we describe the clinical manifestations and the immunological information available about COVID-19 disease. Furthermore, we discuss current therapies under study and the development of vaccines to prevent this disease. © Copyright © 2020 Canedo-MarroquĂn, Saavedra, Andrade, Berrios, RodrĂguez-Guilarte, Opazo, Riedel and Kalergis.https://www.frontiersin.org/articles/10.3389/fimmu.2020.569760/ful
Harnessing content and context for enhanced decision making
In a time in which a significant amount of interpersonal interactions
take place online, one must enquire to which extent are these
milieus suitable for supporting the complexity of our communication.
This is especially important in more sensitive domains, such as the one of
Online Dispute Resolution, in which inefficient communication environments
may result in misunderstandings, poor decisions or the escalation
of the conflict. The conflict manager, in particular, may find his skills
severely diminished, namely in what concerns the accurate perception of
the state of the parties. In this paper the development of a rich communication
framework is detailed that conveys contextual information about
their users, harnessed from the transparent analysis of their behaviour
while communicating. Using it, the conflict manager may not only better
perceive the conflict and how it affects each party but also take better
contextualized decisions, closer to the ones taken in face-to-face settings.This work is part-funded by ERDF - European Regional Development Fund
through the COMPETE Programme (operational programme for competitiveness)
and by National Funds through the FCT { Fundação para a Ciência e a
Tecnologia (Portuguese Foundation for Science and Technology) within project
FCOMP-01-0124-FEDER-028980 (PTDC/EEI-SII/1386/2012) and project PEst-
OE/EEI/UI0752/2014
Antihypertensive therapeutic potential of citronellal
Cardiovascular effects induced by citronellal in rats were investigated in this study. In LNAME hypertensive rats, the oral acute administration of citronellal (200 mg/kg) was able to significantly reduce the blood pressure. In normotensive rats, citronellal (5-40 mg/kg, i.v.) induced hypotension, which was not affected by pre-treatment with atropine, hexamethonium, L-NAME or indomethacin, and bradycardia, which was abolished by atropine and hexamethonium, but not by L-NAME or indomethacin. ECG records revealed that citronellal induced sinoatrial block, which was abolished after atropine. In intact rings of rat mesenteric artery pre-contracted with phenylephrine (10 μM), citronellal (10 –6 to 10 –1 M) was able to induce relaxations (Emax = 106.3 ± 9.4 %) that were not affected by endothelium removal or after pre-contraction with KCl 80 mM. In conclusion, these results demonstrate that citronellal reduces blood pressure. Furthermore, citronellal induces endothelium-independent vasorelaxation in rat artery that appears to involve inhibition of Ca2+ influx.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Dilatonic current-carrying cosmic strings
We investigate the nature of ordinary cosmic vortices in some scalar-tensor
extensions of gravity. We find solutions for which the dilaton field condenses
inside the vortex core. These solutions can be interpreted as raising the
degeneracy between the eigenvalues of the effective stress-energy tensor,
namely the energy per unit length U and the tension T, by picking a privileged
spacelike or timelike coordinate direction; in the latter case, a phase
frequency threshold occurs that is similar to what is found in ordinary neutral
current-carrying cosmic strings. We find that the dilaton contribution for the
equation of state, once averaged along the string worldsheet, vanishes, leading
to an effective Nambu-Goto behavior of such a string network in cosmology, i.e.
on very large scales. It is found also that on small scales, the energy per
unit length and tension depend on the string internal coordinates in such a way
as to permit the existence of centrifugally supported equilibrium
configuration, also known as vortons, whose stability, depending on the very
short distance (unknown) physics, can lead to catastrophic consequences on the
evolution of the Universe.Comment: 10 pages, ReVTeX, 2 figures, minor typos corrected. This version to
appear in Phys. Rev.
Edaphic fauna in soil profile after three decades of different soil management and cover crops in a subtropical region
Abstract This research evaluated the effects of long-term (30 years) winter cover crops under conventional farming system and no-tillage system on edaphic fauna in a Rhodic Hapludox soil, from Paraná State, Brazil. We used three winter cover crops (black oat, hairy vetch and fallow), and as a reference a fragment of natural forest. Soil monoliths were collected at two times, one during the flowering of maize (April 2013) and the other during the flowering of soybean (January 2014). The extraction of the monoliths was carried out in three layers in the soil profile (0-10, 10-20 and 20-30 cm). Seventeen taxonomic groups were sampled. The density of the edaphic fauna is inversely related to soil depth. The winter crops associated with the no-tillage system in long-term resulted in fauna densities similar to the natural environment, with a higher density (density increase of 2.2x) at a depth of 10-20 cm in areas with black oat. At 0-10 cm depth, black oat and vetch under no-tillage systems resulted in an increase of 62% and 69% (April 2013) and 46 and 44% (January 2014), respectively, in the density of soil fauna, when compared to the same winter crops in conventional farming system
Phenotypic, additive genetic and environment correlations of maize landraces populations in family farm systems
Knowledge of the association between characters is very important in the genetic breeding programs, but there is limited information about correlations between traits in maize landraces in the current literature. The objectives of this study were to estimate phenotypic, additive genetic and environment correlations among traits in maize landraces, which were cultivated in family farm systems, in order to guide the participatory breeding on maize landraces. Between 294 and 400 half-sib progenies from the six populations were evaluated, subdivided in triple 7X7 and 10X10 lattice design, respectively, with single row plots of 4 m long and spaced 1.00 Ă— 0.20 m. Estimates of correlation coefficients are reported for nine traits: grain yield (GY), relation grain weight per ear weight (GE), ears per plant (EP), days to flower (DF), plant height (PH), ear height (EH), percentage of root loding (%L), percentage of stalk loding (%BS) and percentage of damaged ears (%DE). A high number of additive genetic correlation (rA) was obtained between grain yield and the other traits, in maize landraces populations, cycles and locations. For grain yield, the highest averages of the rA estimate were with EP (0.67), GE (0.47) and %DE (-0.63). In contrast to the current published researches, negative correlations between grain yield and days to flower were observed.O conhecimento da associação entre caracteres Ă© de grande importância nos programas de melhoramento genĂ©tico, contudo a literatura apresenta limitadas informações sobre correlações em populações de milho crioulo. Os objetivos deste estudo foram estimar correlações fenotĂpicas, genĂ©ticas aditivas e ambientais entre caracteres de populações de milho crioulo, cultivados em sistemas de agricultura familiar, para orientar o programa de melhoramento genĂ©tico participativo. Entre 294 e 400 de progĂŞnies de meios-irmĂŁos de seis populações, foram avaliadas em látices triplos 7X7 e 10X10, respectivamente, com parcelas de 4 m de comprimento e espaçadas 1,00 Ă— 0,20 m. Os coeficientes de correlações foram estimados para nove caracterĂsticas: produtividade de grĂŁos total (GY), relação peso de grĂŁos por peso de espiga (GE), nÂş de espigas por planta (EP), nÂş de dias do florescimento (DF), altura da planta (PH), altura espiga (EH), porcentagem de acamamento (%L), porcentagem de colmos quebrados (%BS) e porcentagem de espigas danificadas (%DE). Houve um alto nĂşmero de correlação genĂ©tica aditiva (rA) entre produtividade de grĂŁos e as demais caracterĂsticas, nas populações de milho crioulo, ciclos e locais. As maiores mĂ©dias das estimativas rA para o produtividade de grĂŁos foram com EP (0,67), GE (0,47) e DE% (-0,63). Diferentemente dos trabalhos publicados, foram observadas correlações negativas entre produtividade de grĂŁos e dias para florescimento
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