Comment on current correlators in QCD at finite temperature

We address some criticisms by Eletsky and Ioffe on the extension of QCD sum rules to finite temperature. We argue that this extension is possible, provided the Operator Product Expansion and QCD-hadron duality remain valid at non-zero temperature. We discuss evidence in support of this from QCD, and from the exactly solvable two- dimensional sigma model O(N) in the large N limit, and the Schwinger model.Comment: 10 pages, LATEX file, UCT-TP-208/94, April 199

Experimental evidence of delocalized states in random dimer superlattices

We study the electronic properties of GaAs-AlGaAs superlattices with intentional correlated disorder by means of photoluminescence and vertical dc resistance. The results are compared to those obtained in ordered and uncorrelated disordered superlattices. We report the first experimental evidence that spatial correlations inhibit localization of states in disordered low-dimensional systems, as our previous theoretical calculations suggested, in contrast to the earlier belief that all eigenstates are localized.Comment: 4 pages, 5 figures. Physical Review Letters (in press

L\u2019IPONATRIEMIA NELL\u2019ANZIANO: UNA PROBLEMATICA SEMPRE ATTUALE

Le alterazioni della concentrazione plasmatica del sodio rappresentano una delle disionie di pi\uf9 frequente riscontro nei pazienti ricoverati e che l\u2019incidenza e la prevalenza aumentano con l\u2019et\ue0. Molteplici fattori correlati all\u2019invecchiamento giocano un ruolo in tal senso; ad esempio, variazioni anatomiche e funzionali, modificazioni della composizione corporea, alterazioni dei meccanismi fisiologici che regolano il metabolismo e l\u2019omeostasi del sodio e dell\u2019acqua. L\u2019aumento dell\u2019incidenza di tali disturbi nella popolazione anziana rappresenta un chiaro esempio di come l\u2019invecchiamento \ue8 in grado di compromettere le capacit\ue0 di compenso, di adattamento e l\u2019omeostasi dell\u2019organismo.Alterations in the plasma concentration of sodium represent one of the most frequently ionic disorders in hospitalized patients. The incidence and prevalence of hyponatremia increase with age. Multiple factors related to aging play a role in this process: for example, anatomical and functional changes, body composition modifications, alterations of physiological mechanisms that regulate metabolism and homeostasis of sodium and water. The increased incidence of these disorders in the older population is a clear example of how aging can affect the ability of compensation, adaptation and homeostasis of the organism

LE IPERNATRIEMIE NELL\u2019ANZIANO

L\u2019pernatremia \ue8 caratterizzata da un deficit di acqua corporea totale rispetto al sodio ed \ue8 definita da una concentrazione plasmatica superiore a 145 mmol/L. L\u2019ipersodiemia nella popolazione geriatrica \ue8 un disturbo comune, associato ad una significativa morbilit\ue0 e mortalit\ue0. Le persone anziane sono predisposte a sviluppare ipernatriemia a causa di modificazioni fisiologiche legate all'et\ue0: ad esempio la diminuzione della sete, una ridotta capacit\ue0 di concentrazione delle urine e la diminuzione del contenuto di acqua corporea totale. I farmaci possono aumentare questa predisposizione. Nelle case di cura e di riposo, l\u2019ipernatremia e la disidratazione sono considerate prevenibili, per cui vengono ritenute indicatori di negligenza e di scarsa qualit\ue0 delle cure.Hypernatremia is characterized by a deficit of total body water relative to total body sodium and is defined by a sodium plasma concentration greater than 145 mmol/L. Hypernatremia in the geriatric population is a common disorder associated with significant morbidity and mortality. Older people are predisposed to developing hypernatremia because of age-related physiologic changes such as decreased thirst drive, impaired urinary concentrating ability, and reduced total body water. Medications may exacerbate this predisposition. In nursing home residents, hypernatremia and dehydration are considered preventable; hence, they are indicators of neglect and substandard care

A Physical Model for SN 2001ay, a normal, bright, extremely slowly declining Type Ia supernova

We present a study of the peculiar Type Ia supernova 2001ay (SN 2001ay). The defining features of its peculiarity are: high velocity, broad lines, and a fast rising light curve, combined with the slowest known rate of decline. It is one magnitude dimmer than would be predicted from its observed value of Delta-m15, and shows broad spectral features. We base our analysis on detailed calculations for the explosion, light curves, and spectra. We demonstrate that consistency is key for both validating the models and probing the underlying physics. We show that this SN can be understood within the physics underlying the Delta-m15 relation, and in the framework of pulsating delayed detonation models originating from a Chandrasekhar mass, white dwarf, but with a progenitor core composed of 80% carbon. We suggest a possible scenario for stellar evolution which leads to such a progenitor. We show that the unusual light curve decline can be understood with the same physics as has been used to understand the Delta-m15 relation for normal SNe Ia. The decline relation can be explained by a combination of the temperature dependence of the opacity and excess or deficit of the peak luminosity, alpha, measured relative to the instantaneous rate of radiative decay energy generation. What differentiates SN 2001ay from normal SNe Ia is a higher explosion energy which leads to a shift of the Ni56 distribution towards higher velocity and alpha < 1. This result is responsible for the fast rise and slow decline. We define a class of SN 2001ay-like SNe Ia, which will show an anti-Phillips relation.Comment: 35 pages, 14 figures, ApJ, in pres

Cryoablation for Small Renal Masses

Advances in imaging techniques (CT and MRI) and widespread use of imaging especially ultrasound scanning have resulted in a dramatic increase in the detection of small renal masses. While open partial nephrectomy is still the reference standard for the management of these small renal masses, its associated morbidity has encouraged clinicians to exploit the advancements in minimally invasive ablative techniques. The last decade has seen the rapid development of laparoscopic partial nephrectomy and novel ablative techniques such as, radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), and cryoablation (CA). In particular, CA for small renal masses has gained popularity as it combines nephron-sparing surgery with a minimally invasive approach. Studies with up to 5-year followup have shown an overall and cancer-specific 5-year survival of 82% and 100%, respectively. This manuscript will focus on the principles and clinical applications of cryoablation of small renal masses, with detailed review of relevant literature

Modelling transport and real-estate values interactions in urban systems

This article presents hedonic Multiple Linear Regression models (MLR), Spatial Auto-Regressive hedonic models (SAR), Spatial autoregressive hedonic in the Error term Models (SEM) and spatial Durbin hedonic Models (SDM) to estimate houses price variations in metropolitan areas as a result of changing environmental and accessibility conditions. The goodness of fit of the different models has been compared along with a series of hypotheses about the performance of the specifications considering spatial relationships between observations. The case study for such analysis was the urban area of Santander (Spain). It has been observed the models which considered spatial dependence between observations offered a greater degree of fit in a scenario showing strong spatial correlation in MLR residuals. The SEM model combined with a Queen-Contiguity matrix provided a good fit to the data and at the same time presented significant parameters with theoretically coherent signs. This model estimated increases of 1.8% for each additional transit line present in the areas of housing, as well as a reduction of 1.1% in their prices for each additional minute in travelling time to the Central Business District. Closeness to the train stations, however, implied reductions in house prices

Phenomenology of BsB_s Decays

Using the QCD sum rules technique we study several aspects of the phenomenology of the b-flavoured strange meson $B_s^0$. In particular, we evaluate the mass of the particle, the leptonic constant and the form factors of the decays $\overline {B_s^0} \to D^{+}_s \ell^- \bar\nu$, $\overline {B_s^0} \to D^{*+}_s \ell^- \bar\nu$, $\overline {B_s^0} \to K^{*+} \ell^- \bar\nu$. We also calculate, in the factorization approximation, a number of two-body non leptonic $\overline {B_s^0}$ decays.Comment: 19 pages, 2 figures (not included) available upon request, LaTex, BARI-TH/93-139, UTS-DFT-93-1

Conservation Laws in Smooth Particle Hydrodynamics: the DEVA Code

We describe DEVA, a multistep AP3M-like-SPH code particularly designed to study galaxy formation and evolution in connection with the global cosmological model. This code uses a formulation of SPH equations which ensures both energy and entropy conservation by including the so-called \bn h terms. Particular attention has also been paid to angular momentum conservation and to the accuracy of our code. We find that, in order to avoid unphysical solutions, our code requires that cooling processes must be implemented in a non-multistep way. We detail various cosmological simulations which have been performed to test our code and also to study the influence of the \bn h terms. Our results indicate that such correction terms have a non-negligible effect on some cosmological simulations, especially on high density regions associated either to shock fronts or central cores of collapsed objects. Moreover, they suggest that codes paying a particular attention to the implementation of conservation laws of physics at the scales of interest, can attain good accuracy levels in conservation laws with limited computational resources.Comment: 36 pages, 10 figures. Accepted for publication in The Astrophysical Journa