4,695 research outputs found
Time Series Estimates of the Italian Consumer Confidence Indicator
This work shows that Italian consumer confidence indicator (CCI) is non-stationary and, therefore, can be estimated with the time series methods. It is found that a long-run relationship exists between CCI, short-term interest rate, industrial production index and the difference between perceived and measured inflation. The use of time series methods to estimate CCI for Italy is a novelty in the literature.Consumer confidence indicator, Short-term interest rate, Perceived rate of inflation, Cointegration.
Effects of Sucrose on the Internal Dynamics of Azurin
AbstractSucrose is a natural osmolyte accumulated in cells of organisms as they adapt to environmental stresses. In vitro, sucrose increases protein stability and forces partially unfolded structures to refold. Its effects on the native fold structure and dynamics are not fully established. This study, utilizing Trp phosphorescence spectroscopy, examined the influence of molar concentrations of sucrose on the flexibility of metal-free azurin from Pseudomonas aeruginosa. In addition, by means of specific mutants of the test protein, namely I7S, F110S, and C3A/C26A, that altered its thermodynamic stability, its intrinsic flexibility, and the extent of internal hydration, this investigation sought to identify possible correlations between these features of protein structure and the influence of the osmolyte on protein dynamics. Alterations of structural fluctuations were assessed by both the intrinsic phosphorescence lifetime (τ), which reports on local structure about the triplet probe, and the acrylamide bimolecular quenching rate constant (kq) that is a measure of the average acrylamide diffusion coefficient through the macromolecule. From the modulation of τ and kq across a wide temperature range and up to a concentration of 2M sucrose, it is concluded that sucrose attenuates structural fluctuations principally when macromolecules are internally hydrated and thermally expanded. Preliminary tests with trehalose and xylitol suggest that the effects of sucrose are general of the polyol class of osmolytes
La oximetría de pulso como alternativa de evaluación objetiva que apoye la valoración clínica de la deglución en pacientes con accidente cerebrovascular en etapa aguda
83 p.El propósito de este estudio es determinar si la presencia de disfagia neurogénica en sujetos con accidente cerebro vascular (ACV) en etapa aguda diagnosticados a través de la evaluación clínica de la deglución se asocia a los cambios en los niveles de saturación parcial de oxigeno en la sangre (SPO2) al momento de la evaluación fonoaudiológica. Esta evaluación consistió en la aplicación de un protocolo de evaluación clínica de la deglución y la medición de los niveles de SPO2. La muestra incluye 30 sujetos con disfagia neurogénica secundaria a ACV en etapa aguda (grupo estudio) y 30 sujetos sanos, pareados por edad y sexo (grupo control). Los resultados sugieren tres hallazgos importantes: la evaluación clínica de la deglución con líquidos puede ser complementada con mediciones de SPO2 en la sangre, el cambio de la SPO2 tiende a ser mayor en sujetos con disfagias más severas que en aquellos con disfagias más leves y las mediciones de la SPO2 en sujetos normales al momento de la deglución no presentan mayores cambios. Por lo tanto la evaluación de los niveles de SPO2 en la sangre es un buen método de evaluación que complementa la evaluación clínica realizada por el fonoaudiólogo.
Palabras Claves: Disfagia neurogénica, oximetría de pulso, saturación parcial de oxígeno
Risk Factors for Nonplatelet Thromboxane Generation After Coronary Artery Bypass Graft Surgery
BACKGROUND: Persistent thromboxane (TX) generation while receiving aspirin therapy is associated with an increased risk of cardiovascular events. The Reduction in Graft Occlusion Rates (RIGOR) study found that aspirin-insensitive TXA2 generation, indicated by elevated urine 11-dehydro-TXB2 (UTXB2) 6 months after coronary artery bypass graft surgery, was a potent risk factor for vein graft thrombosis and originated predominantly from nonplatelet sources. Our goal was to identify risks factors for nonplatelet TXA2 generation.
METHODS AND RESULTS: Multivariable modeling was performed by using clinical and laboratory variables obtained from 260 RIGOR subjects with verified aspirin-mediated inhibition of platelet TXA2 generation. The strongest variable associated with UTXB2 6 months after surgery, accounting for 47.2% of the modeled effect, was urine 8-iso-prostaglandin (PG)F2alpha, an arachidonic acid metabolite generated nonenzymatically by oxidative stress (standardized coefficient 0.442, P \u3c 0.001). Age, sex, race, lipid therapy, creatinine, left ventricular ejection fraction, and aspirin dose were also significantly associated with UTXB2 (P \u3c 0.03), although they accounted for only 4.8% to 10.2% of the modeled effect. Urine 8-iso-PGF2alpha correlated with risk of vein graft occlusion (odds ratio 1.67, P=0.001) but was not independent of UTXB2. In vitro studies revealed that endothelial cells generate TXA2 in response to oxidative stress and direct exposure to 8-iso-PGF2alpha.
CONCLUSIONS: Oxidative stress-induced formation of 8-iso-PGF2alpha is strongly associated with nonplatelet thromboxane formation and early vein graft thrombosis after coronary artery bypass graft surgery. The endothelium is potentially an important source of oxidative stress-induced thromboxane generation. These findings suggest therapies that reduce oxidative stress could be useful in reducing cardiovascular risks associated with aspirin-insensitive thromboxane generation
Twisting all the way: from Classical Mechanics to Quantum Fields
We discuss the effects that a noncommutative geometry induced by a Drinfeld
twist has on physical theories. We systematically deform all products and
symmetries of the theory. We discuss noncommutative classical mechanics, in
particular its deformed Poisson bracket and hence time evolution and
symmetries. The twisting is then extended to classical fields, and then to the
main interest of this work: quantum fields. This leads to a geometric
formulation of quantization on noncommutative spacetime, i.e. we establish a
noncommutative correspondence principle from *-Poisson brackets to
*-commutators. In particular commutation relations among creation and
annihilation operators are deduced.Comment: 32 pages. Added references and details in the introduction and in
Section
Boltzmann Suppression of Interacting Heavy Particles
Matsumoto and Yoshimura have recently argued that the number density of heavy
particles in a thermal bath is not necessarily Boltzmann-suppressed for T << M,
as power law corrections may emerge at higher orders in perturbation theory.
This fact might have important implications on the determination of WIMP relic
densities. On the other hand, the definition of number densities in a
interacting theory is not a straightforward procedure. It usually requires
renormalization of composite operators and operator mixing, which obscure the
physical interpretation of the computed thermal average. We propose a new
definition for the thermal average of a composite operator, which does not
require any new renormalization counterterm and is thus free from such
ambiguities. Applying this definition to the model of Matsumoto and Yoshimura
we find that it gives number densities which are Boltzmann-suppressed at any
order in perturbation theory. We discuss also heavy particles which are
unstable already at T=0, showing that power law corrections do in general
emerge in this case.Comment: 7 pages, 5 figures. New section added, with the discussion of the
case of an unstable heavy particle. Version to appear on Phys. Rev.
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