1,644 research outputs found
Estabilidade osmótica dos fluÃdos celômicos de um pepino do mar (Holothuria grisea) e de uma estrela-do-mar (Asterina stellifera) (Echinodermata) expostos ao ar durante a maré baixa: um estudo de campo
Animais de entre-marés podem ser expostos ao ar durante a maré baixa,
por pelo menos 1-2 horas. Os animais expostos ao ar são susceptÃveis a
perda de sal e/ou entrada de água durante chuva intensa, ou perda de água
pela ação de dessecação do sol. A osmolalidade de amostras de fluido
celômico obtidas do pepino-do-mar Holothuria grisea e da estrela-do-mar
Asterina stellifera expostas ao ar, ou de animais controles imersos na
água do mar adjacente foi determinada. As amostras foram obtidas
imediatamente após a exposição ao ar, e novamente após uma hora de
exposição ao ar, durante a maré baixa no campo, em tempo nublado,
chuvoso, ou ensolarado, na Praia rochosa do Quilombo, Penha, Sul do
Brasil. Uma hora de exposição a qualquer das condições climáticas
indicadas não alterou a osmolalidade dos fluidos celômicos. Houve pequena
redução nas osmolalidades dos fluidos celômicos durante a exposição ao
ar com precipitação de chuva. Sugere-se que estes equinodermas possam
imediatamente detectar sua exposição ao ar, e possam então reduzir a
permeabilidade osmótica de sua parede do corpo, para evitar perda de
água para o ar ou entrada de água/saÃda de sal durante a chuva.
ABSTRACT
Intertidal animals can be exposed to the air during low tide, for
at least 1-2 hours. Animals exposed to the air are subject to salt loss
(or water gain) from heavy rains or volume loss from the desiccating
action of the sun. Coelomic fluid samples obtained from the
sea-cucumber Holothuria grisea and the starfish Asterina stellifera
exposed to the air or from control animals submerged in surrounding
sea water have been assayed for osmolality. Samples were obtained
right after air exposure and again after 1 hour of exposure to
the air during low tide in the field, either under cloudy, rainy or
sunny weather conditions, in the rocky beach of Quilombo, Penha,
Southern Brazil. One hour of exposure to any of the conditions did
not change coelomic fluid osmolalities. There was a slight reduction
in coelomic fluid osmolalities upon air exposure during rainfall.
It is suggested that these echinoderms can somehow immediately
detect air exposure and reduce their body wall permeability to
avoid water loss or water influx/salt loss during rainfall.
RÉSUMÉ
Animaux dentre-marées peuvent êtres exposés a lair libre
pendant le reflux de la marée, pour environ une ou deux heures
seulement. Ces animaux, quand exposés a lair libre, sont susceptibles
de perdre du sel et dabsorber de leau pendant une période de pluie
intense. Par contre, ils peuvent perdre de leau si soumis a laction
de dessèchement due a une éxposition au soleil. On a réussi a
determiner losmolalité déchantillons du fluide celomique obtenus
du Pépin-de-mer Holothuria grisea et de lÉtoile-de-mer Asterina
stellifera exposés a lair libre, e danimaux-controles immergés
dans leau de mer voisin. Les échantillons ont été obtenus tout de
suite après lexposition à lair et, une seconde fois, après une heure
dexposition à lair libre, pendant la durée de la marée basse, soit
sous la pluie, soit au soleil ou soit sous un ciel ombrageux, Ã la
plage rocailleuse de Quilombo, Penha, au sud du Brésil. Une heure déxposition à nimporte quelles conditions climatiques indiquées,
nont pas pu altérer losmolalité des fluides celomiques, ce que
sugère la conclusion que ces échinodermes peuvent détecter
immédiatement sa exposition à lair libre et peuvent tout de suite
réduire la permeabilité osmotique de la membrane que recouvre
son corps pour éviter perdre deau et, de la même façon, reduire
labsortion de leau pendant la pluie. On a observé une petite
réduction de fluides celomiques pendant lexposition a lair, avec
ocurrence de pluie
Race, Skin Color and Genetic Ancestry: Implications for Biomedical Research on Health Disparities
Defining race continues to be a nemesis. Knowledge from human genetic research continuously challenges the notion that race and biology are inextricably linked, with implications across biomedical and public health disciplines. While it has become fashionable for scientists to declare that race is merely a social construction, there is little practical value to this belief since few in the public believe and act on it. In the U.S., race has largely been based on skin color and ancestry, both of which exhibit large variances within communities of color. Yet biomedical studies continue to examine black / white group differences in health. Here we discuss why using race in biomedical studies is problematic using examples from two U.S. groups (African and Hispanic Americans) which transcend ‘racial’ boundaries and bear the burden of health disparities
Evolution of helium triplet transits of close-in gas giants orbiting K-dwarfs
Atmospheric escape in exoplanets has traditionally been observed using
hydrogen Lyman- and H- transmission spectroscopy, but more
recent detections have utilised the metastable helium triplet at 1083nm.
Since this feature is accessible from the ground, it offers new possibilities
for studying atmospheric escape. Our goal is to understand how the
observability of escaping helium evolves during the lifetime of a highly
irradiated gas giant. We extend our previous work on 1-D self-consistent
hydrodynamic escape from hydrogen-only atmospheres as a function of planetary
evolution to the first evolution-focused study of escaping hydrogen-helium
atmospheres. Additionally, using these novel models we perform helium triplet
transmission spectroscopy. We adapt our previous hydrodynamic escape model to
now account for both hydrogen and helium heating and cooling processes and
simultaneously solve for the population of helium in the triplet state. To
account for the planetary evolution, we utilise evolving predictions of
planetary radii for a close-in 0.3 gas giant and its received
stellar flux in X-ray, hard and soft EUV, and mid-UV wavelength bins assuming a
K dwarf stellar host. We find that the helium triplet signature diminishes with
evolution. Our models suggest that young (~Myr), close-in gas
giants ( to ) should produce helium 1083nm transit
absorptions of or , for a slow or fast-rotating K dwarf,
respectively, assuming a 2 helium abundance.Comment: 20 pages, 13 figures, 4 tables; accepted for publication in MNRA
Role of MOB4 in cell proliferation and neurogenesis
Signaling pathways that integrate a large set of inputs (both extra- and intracellular) to control cell proliferation are essential during both development and adult stages to guarantee organism homeostasis. Mobs are small adaptor proteins that participate in several of these signaling pathways. Here, we review recent advances unravelling Mob4 cellular functions, a highly conserved non-catalytic protein, that plays a diversity of roles in cell proliferation, sperm cell differentiation and is simultaneously involved in synapse formation and neural development. In addition, the gene is often overexpressed in a large diversity of tumors and is linked to poor clinical outcomes. Nevertheless, Mob4 molecular functions remain poorly defined, although it integrates the core structure of STRIPAK, a kinase/phosphatase protein complex, that can act upstream of the Hippo pathway. In this review we focus on the recent findings of Mob4 functions, that have begun to clarify its critical role on cell proliferation and the development of tissues and individuals.Grant number ALG-01-0145-FEDER-030014info:eu-repo/semantics/publishedVersio
Aquecimento ôhmico: novos desafios no tratamento térmico de materiais
[Excerto] Introdução: O tratamento térmico de materiais encontra-se dentre os processos mais
utilizados industrialmente. Na indústria de alimentos, por exemplo, o tratamento térmico (por possuir ação letal sobre microorganismos) é o principal procedimento fÃsico de que a tecnologia de alimentos dispõe para
aumentar a vida útil dos alimentos (Ordóñez et al., 2005). Desta forma, novos métodos de aquecimento
que acarretem em baixo gasto energético ou em maior eficiência energética continuam a atrair interesse Palaniappan e Sastry, 1992). Dentre as tecnologias de aquecimento emergentes, o aquecimento
ôhmico apresenta-se bastante promissor. [...]info:eu-repo/semantics/publishedVersio
A solution for funding the development of technology in oilwell drilling
This article proposes a novel methodology to solve an existing gap in benchmark definition by the adoption of statistically defined benchmarks as references to test products or technical procedures. In a win–win partnership, remuneration is made upon realistic bases of comparison being proportional to existing risks. However, establishing values for benchmarks is rarely unanimous if asked to different persons involved in drilling analysis. Conventional benchmarking, which enhances few results and leaves aside poor operational performances, produces references that do not properly represent the geological environment. Nonetheless, when testing new products, it serves as reference to remunerate suppliers. The review of an optimization program, which resulted in a world record of drilling rate of penetration, reveals the financial magnitude of the savings produced, proposing the method discussed as a reliable solution to the development of technology.publishedVersio
Black holes with synchronised Proca hair: linear clouds and fundamental non-linear solutions
Recent studies have made key progress on the black hole/solitonic solutions
of the Einstein-Proca system. Firstly, fully non-linear dynamical evolutions of
the Kerr black hole superradiant instability, triggered by a Proca field, have
shown the formation of a new equilibrium state, a spinning black hole with
synchronised Proca hair. Secondly, non-linear evolutions of spinning Proca
stars have established that they are dynamically stable, unlike their scalar
cousins. Thirdy, separability of the Proca equation on the Kerr background has
been achieved. Motivated by these results, in this paper we reconsider Kerr
black holes with synchronised Proca hair. The separability of the Proca
equation on the Kerr background allows us to examine the stationary Proca
clouds in greater detail, in particular their dependence on the different
quantum numbers. These stationary clouds occur at a set of existence lines in
the Kerr parameter space, from which the black holes with synchronised Proca
hair bifurcate. We construct the domain of existence of these black holes,
comparing the fundamental states missed in the original study with the first
excited states and with the cousin scalar model, giving illustrative examples
of Kerr-like and non-Kerr-like BHs. In the vanishing event horizon limit, these
hairy black holes connect to the fundamental states of spinning Proca stars,
which include the dynamically stable solutions.Comment: 36 pages, 13 figure
On capillary viscosity measurements: how far do surface tension effects go?
Viscosity is a fundamental thermophysical property of liquids making it very important particularly in the industry. Capillary viscometers have been widely used for viscosity measurements in different applications, the most relevant being the definition of viscosity standards, traceable to the primary water viscosity standard, by metrological institutions and industrial applications, mostly for quality control. Practical viscometry is based on the internationally accepted primary standard value for the kinematic viscosity of water at 20ºC and atmospheric pressure, which has been measured using capillary viscometers [1]. However, due to the water surface tension, viscosity measurements which have been related to water as a primary standard, can be significantly affected. It is difficult to rigorously assess the surface tension effects on capillary viscometers, and the practical way to avoid this problem is to use long capillaries, which are not appropriate for routine measurements [1-3]. After several experimental studies, using different types of viscometers, the usual procedure to correct surface tension effects in capillary viscosity measurements adopted by different authors, is to employ an empirical expression [1-4]. Additionally, other types of problems exist as the need to perform a kinetic energy correction which must also be taken into consideration [1].
The main goal of this work was to perform the calibration of a suspended-level, or Ubbelohde, capillary viscometer, which is not a long capillary viscometer, as well as the study of corrections to be used for the measurements performed with it.
The experimental work covers the calibration of that Ubbelohde capillary viscometer, the evaluation of the uncertainty of the corresponding viscometer constant and the overall uncertainty of the measurements performed with it. This study includes the evaluation of the necessary corrections for kinetic energy and surface tension effects and, finally, the analysis of the case of a set of measurements performed with n-tetradecane.
The ultimate purpose of this work is to obtain the lowest uncertainty for the Ubbelohde capillary viscometer 541 01/Ia, and to understand the need for the corrections that must be considered when using capillary viscometers and how they should be applied.N/
Enhanced lithium depletion in Sun-like stars with orbiting planets
The surface abundance of lithium on the Sun is 140 times less than
protosolar, yet the temperature at the base of the surface convective zone is
not hot enough to burn Li. A large range of Li abundances in solar type stars
of the same age, mass and metallicity is observed, but theoretically difficult
to understand. An earlier suggestion that Li is more depleted in stars with
planets was weakened by the lack of a proper comparison sample of stars without
detected planets. Here we report Li abundances for an unbiased sample of
solar-analogue stars with and without detected planets. We find that the
planet-bearing stars have less than 1 per cent of the primordial Li abundance,
while about 50 per cent of the solar analogues without detected planets have on
average 10 times more Li. The presence of planets may increase the amount of
mixing and deepen the convective zone to such an extent that the Li can be
burned.Comment: 13 pages, 2 figure
The barriers dentists face to communicate cancer diagnosis:self-assessment based on SPIKES protocol
This study aimed to characterize the barriers faced by Brazilian dentists to deliver bad news (DBN) about oral and oropharyngeal cancer diagnoses to patients by using a questionnaire based on the guidelines of the SPIKES protocol. This was an observational cross-sectional study. The questionnaire contained 27 questions based on the SPIKES protocol, which were answered in the SurveyMonkey platform. A total of 186/249 dentists answered the questionnaire. The main specialties reported were 36.02% oral medicine, 21.5% oral pathology, and 9.13% oral and maxillofacial surgery. A total of 44.6% expressed concern about the patient?s emotional reactions, and 46.24% of respondents had never participated in any specific training to communicate bad news. The lack of training and low confidence in dealing with patients? emotional reactions dentists were considered the greatest barriers to DBNs. Moreover, most dentists who participated in the survey believe that a protocol to guide the communication of bad news would be useful for clinical practice. For those protocols to be used by dentists, training is critical for these protocols to be incorporated by professionals
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