9,043 research outputs found
Metabolic Effects of Bariatric Surgery in Mouse Models of Circadian Disruption
Background/Objectives:
Mounting evidence supports a link between circadian disruption and metabolic disease. Humans with circadian disruption (for example, night-shift workers) have an increased risk of obesity and cardiometabolic diseases compared with the non-disrupted population. However, it is unclear whether the obesity and obesity-related disorders associated with circadian disruption respond to therapeutic treatments as well as individuals with other types of obesity. Subjects/Methods:
Here, we test the effectiveness of the commonly used bariatric surgical procedure, Vertical Sleeve Gastrectomy (VSG), in mouse models of genetic and environmental circadian disruption. Results:
VSG led to a reduction in body weight and fat mass in both ClockΔ19 mutant and constant-light mouse models (PP\u3e0.05). Within circadian-disrupted models, VSG also led to improved glucose tolerance and lipid handling (P\u3c0.05). Conclusions:
Together these data demonstrate that VSG is an effective treatment for the obesity associated with circadian disruption, and that the potent effects of bariatric surgery are orthogonal to circadian biology. However, as the effects of bariatric surgery are independent of circadian disruption, VSG cannot be considered a cure for circadian disruption. These data have important implications for circadian-disrupted obese patients. Moreover, these results reveal new information about the metabolic pathways governing the effects of bariatric surgery as well as of circadian disruption
Structure formation in the presence of relativistic heat conduction: corrections to the Jeans wave number with a stable first order in the gradients formalism
The problem of structure formation in relativistic dissipative fluids was
analyzed in a previous work within Eckart's framework, in which the heat flux
is coupled to the hydrodynamic acceleration, additional to the usual
temperature gradient term. It was shown that in such case, the pathological
behavior of fluctuations leads to the disapperance of the gravitational
instability responsible for structure formation. In the present work the
problem is revisited now using a constitutive equation derived from
relativistic kinetic theory. The new relation, in which the heat flux is not
coupled to the hydrodynamic acceleration, leads to a consistent first order in
the gradients formalism. In this case the gravitational instability remains,
and only relativistic corrections to the Jeans wave number are obtained. In the
calculation here shown the non-relativistc limit is recovered, opposite to what
happens in Eckart's case.Comment: 10 pages, no figure
Mutagenicity of 4-nitroquinoline l-oxide and three hair dye components in Sordaria brevicollis
Mutagenicity of 4-nitroquinoline 1-oxide and three hair dye components in Sordaria brevicolli
Determinación de relaciones nivel – caudal simple o compleja en un rÃo. Caso del rÃo Cauca
(Eng) The stage – discharge relationship in a river, or rating curve, is very useful because it allows calculating the discharg
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es from measured stages or water levels in a gauge station. For a nearly steady regime a discharge corresponds to
a water level (simple relationship). However, frequently different circumstances can originate a complex relation
between waters levels and discharges and then a discharge can be referred to two water levels and vice versa. In
this study, simple and complex rating curves were determined in La Balsa hydrometric station, located 27 km
downstream of Salvajina reservoir (Cauca river, Colombia). The simple curve was calculated by applying the log
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arithmic method, which allows identifying the characteristics of the type of control that determines the water level
– discharge relationship. The complex curve was calculated by using the method of storage per unit rate of variation
in water levels, which allows adjusting the discharge obtained with the rating curve for steady flow considering a
storage due to the variation in the level. The results show significant differences in the estimated discharges through
the two relationships. By applying the two rating curves for a moderate flood (01/01/1999) differences up to 19%
were estimated between both calculated discharges. In consequence, in order to get the appropriated rating curve it
should to carry out a rigorous analysis of the flow conditions on the river reaches of the hydrometric station.(Spa) La relación nivel de agua – caudal en un rÃo, denominada también curva de calibración, es de gran utilidad práctica
pues permite estimar los caudales a partir de los niveles registrados en una estación hidrométrica. Cuando el régimen
es aproximadamente permanente a cada nivel le corresponde un caudal (relación simple). No obstante, frecuente
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mente diferentes circunstancias pueden generar una relación compleja entre los niveles y los caudales, donde un
caudal puede estar relacionado con dos niveles de agua y viceversa. En el presente estudio se determinaron las cur
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vas de calibración simple y compleja en la estación La Balsa, localizada 27 km aguas abajo del embalse de Salvajina
(rÃo Cauca, Colombia). La curva simple se calculó mediante el método logarÃtmico, el cual permite identificar las
caracterÃsticas del tipo de control que determina la relación nivel – caudal. La curva compleja se calculó según el
método de almacenamiento por unidad de tasa de cambio en los niveles de agua, el cual permite ajustar el caudal
obtenido en la curva nivel – caudal para régimen permanente considerando un almacenamiento debido al cambio en
el nivel. Los resultados muestran diferencias importantes en los caudales estimados por medio de las dos relaciones.
Al aplicar las dos curvas de calibración para una creciente moderada (01/01/1999) se encontraron diferencias hasta
de un 19% entre los caudales calculados. En consecuencia, para establecer la curva de calibración nivel-caudal
apropiada se debe realizar un análisis riguroso de las condiciones del flujo, tanto en la estación hidrométrica como
aguas arriba y aguas abajo de ella
The Rayleigh-Brillouin Spectrum in Special Relativistic Hydrodynamics
In this paper we calculate the Rayleigh-Brillouin spectrum for a relativistic
simple fluid according to three different versions available for a relativistic
approach to non-equilibrium thermodynamics. An outcome of these calculations is
that Eckart's version predicts that such spectrum does not exist. This provides
an argument to question its validity. The remaining two results, which differ
one from another, do provide a finite form for such spectrum. This raises the
rather intriguing question as to which of the two theories is a better
candidate to be taken as a possible version of relativistic non-equilibrium
thermodynamics. The answer will clearly require deeper examination of this
problem.Comment: 13 pages, no figures. Accepted for publication in Phys. Rev.
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