3,977 research outputs found
Sodium intake and hypertension
The close relationship between hypertension and dietary sodium intake is widely recognized and supported by several studies. A reduction in dietary sodium not only decreases the blood pressure and the incidence of hypertension, but is also associated with a reduction in morbidity and mortality from cardiovascular diseases. Prolonged modest reduction in salt intake induces a relevant fall in blood pressure in both hypertensive and normotensive individuals, irrespective of sex and ethnic group, with larger falls in systolic blood pressure for larger reductions in dietary salt. The high sodium intake and the increase in blood pressure levels are related to water retention, increase in systemic peripheral resistance, alterations in the endothelial function, changes in the structure and function of large elastic arteries, modification in sympathetic activity, and in the autonomic neuronal modulation of the cardiovascular system. In this review, we have focused on the effects of sodium intake on vascular hemodynamics and their implication in the pathogenesis of hypertensio
Sensitivity limits of a Raman atom interferometer as a gravity gradiometer
We evaluate the sensitivity of a dual cloud atom interferometer to the
measurement of vertical gravity gradient. We study the influence of most
relevant experimental parameters on noise and long-term drifts. Results are
also applied to the case of doubly differential measurements of the
gravitational signal from local source masses. We achieve a short term
sensitivity of 3*10^(-9) g/Hz^(-1/2) to differential gravity acceleration,
limited by the quantum projection noise of the instrument. Active control of
the most critical parameters allows to reach a resolution of 5*10^(-11) g after
8000 s on the measurement of differential gravity acceleration. The long term
stability is compatible with a measurement of the gravitational constant G at
the level of 10^(-4) after an integration time of about 100 hours.Comment: 19 pages, 20 figure
Atom Interferometry with the Rb Blue Transitions
We demonstrate a novel scheme for Raman-pulse and Bragg-pulse atom
interferometry based on the blue transitions of
Rb that provides an increase by a factor of the interferometer
phase due to accelerations with respect to the commonly used infrared
transition at 780 nm. A narrow-linewidth laser system generating more than 1 W
of light in the 420-422 nm range was developed for this purpose. Used as a
cold-atom gravity gradiometer, our Raman interferometer attains a stability to
differential acceleration measurements of at 1 s and
after 2000 s of integration time. When operated on
first-order Bragg transitions, the interferometer shows a stability of
g at 1 s, averaging to g after 2000 s of
integration time. The instrument sensitivity, currently limited by the noise
due to spontaneous emission, can be further improved by increasing the laser
power and the detuning from the atomic resonance. The present scheme is
attractive for high-precision experiments as, in particular, for the
determination of the Newtonian gravitational constant
Skeleton and fractal scaling in complex networks
We find that the fractal scaling in a class of scale-free networks originates
from the underlying tree structure called skeleton, a special type of spanning
tree based on the edge betweenness centrality. The fractal skeleton has the
property of the critical branching tree. The original fractal networks are
viewed as a fractal skeleton dressed with local shortcuts. An in-silico model
with both the fractal scaling and the scale-invariance properties is also
constructed. The framework of fractal networks is useful in understanding the
utility and the redundancy in networked systems.Comment: 4 pages, 2 figures, final version published in PR
Salicylate toxicity model of tinnitus
Salicylate, the active component of the common drug aspirin, has mild analgesic, antipyretic, and anti-inflammatory effects at moderate doses. At higher doses, however, salicylate temporarily induces moderate hearing loss and the perception of a high-pitch ringing in humans and animals. This phantom perception of sound known as tinnitus is qualitatively similar to the persistent subjective tinnitus induced by high-level noise exposure, ototoxic drugs, or aging, which affects ∼14% of the general population. For over a quarter century, auditory scientists have used the salicylate toxicity model to investigate candidate biochemical and neurophysiological mechanisms underlying phantom sound perception. In this review, we summarize some of the intriguing biochemical and physiological effects associated with salicylate-induced tinnitus, some of which occur in the periphery and others in the central nervous system. The relevance and general utility of the salicylate toxicity model in understanding phantom sound perception in general are discussed
Testing gravity with atomic quantum sensors
In this article, three experiments aimed at the detection of gravitational effects with atomic sensors are reported. In the first experiment, a gradiometer is used to perform a precision measurement of the Newtonian gravitational
constant G. In the second experiment, a similar apparatus is used to provide a test of the Weak Equivalence Principle for atoms in different internal states and in a coherent superposition of internal states. Finally, in the third experiment, a new kind of interferometer operating on a single-photon transition is described. This sensor
is a promising candidate for the detection of low frequency gravitational waves
Aortic dilatation in Marfan syndrome: Role of arterial stiffness and fibrillin-1 variants
Objective: Marfan syndrome (MFS) is an autosomal dominant genetic disorder characterized by aortic root dilation and dissection and an abnormal fibrillin-1 synthesis. In this observational study, we evaluated aortic stiffness in MFS and its association with ascending aorta diameters and fibrillin-1 genotype. Methods: A total of 116 Marfan adult patients without history of cardiovascular surgery, and 144 age, sex, blood pressure and heart rate matched controls were enrolled. All patients underwent arterial stiffness evaluation through carotid-femoral pulse wave velocity (PWV) and central blood pressure waveform analysis (PulsePen tonometer). Fibrillin-1 mutations were classified based on the effect on the protein, into 'dominant negative' and 'haploinsufficient' mutations. Results: PWV and central pulse pressure were significantly higher in MFS patients than in controls [respectively 7.31 (6.81-7.44) vs. 6.69 (6.52-6.86)m/s, P=0.0008; 41.3 (39.1-43.5) vs. 34.0 (32.7-35.3)mmHg, P<0.0001], with a higher age-related increase of PWV in MFS (β 0.062 vs. 0.036). Pressure amplification was significantly reduced in MFS [18.2 (15.9-20.5) vs. 33.4 (31.6-35.2)%, P<0.0001]. Central pressure profile was altered even in MFS patients without aortic dilatation. Multiple linear regression models showed that PWV independently predicted aortic diameters at the sinuses of Valsalva (ß=0.243, P=0.002) and at the sinotubular junction (ß=0.186, P=0.048). PWV was higher in 'dominant negative' than 'haploinsufficient' fibrillin-1 mutations [7.37 (7.04-7.70) vs. 6.60 (5.97-7.23)m/s, P=0.035], although this difference was not significant after adjustment. Conclusion: Aortic stiffness is increased in MFS, independently from fibrillin-1 genotype and is associated with diameters of ascending aorta. Alterations in central hemodynamics are present even when aortic diameter is within normal limits. Our findings suggest an accelerated arterial aging in MFS
“Érase una montaña de violetas”: muerte, deseo, lenguaje en el Diario de la muerte de Sara de Ibáñez
El presente estudio pretende enfocar la
obra Diario de la muerte, de la poeta uruguaya Sara
de Ibáñez. Con el apoyo crítico de la semiótica y de
las teorías psicoanalíticas de matriz freudiano-lacaniana,
se demostrará cómo la concepción poética
subyacente al libro descansa en la relación antropológica
fundamental existente entre subjetividad y
lenguaje. Además, se reconsiderará el motivo trasversal
de la muerte en función de su inscripción
dentro del marco de una poética del deseo. Tal postura
teórica permitirá llegar a una descripción exhaustiva
de las tácticas de representación textual de
dicha relación puestas en acto en el libro.The paper aims to peruse the book Diario
de la muerte by the Uruguayan poet Sara de Ibáñez.
Using as a critical support semiotic and Freudian-
Lacanian psychoanalytic theories, it will be demonstrated
how the very deep poetical conception of the
book lies in a fundamental anthropological relation
between selfness and language. Moreover, the
death leitmotiv will be reconsidered as a function of
a poetics of desire. This theoretical approach to the
text allows to achieve a thorough description of the
way this relation takes form through poetry’s linguistic
structures
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