Free boundary regularity for harmonic measures and Poisson kernels

One of the basic aims of this paper is to study the relationship between the geometry of ``hypersurface like'' subsets of Euclidean space and the properties of the measures they support. In this context we show that certain doubling properties of a measure determine the geometry of its support. A Radon measure is said to be doubling with constant C if C times the measure of the ball of radius r centered on the support is greater than the measure of the ball of radius 2r and the same center. We prove that if the doubling constant of a measure on \R^{n+1} is close to the doubling constant of the n-dimensional Lebesgue measure then its support is well approximated by n-dimensional affine spaces, provided that the support is relatively flat to start with. Primarily we consider sets which are boundaries of domains in \R^{n+1}. The n-dimensional Hausdorff measure may not be defined on the boundary of a domain in R^{n+1}. Thus we turn our attention to the harmonic measure which is well behaved under minor assumptions. We obtain a new characterization of locally flat domains in terms of the doubling properties of their harmonic measure. Along these lines we investigate how the ``weak'' regularity of the Poisson kernel of a domain determines the geometry of its boundary.Comment: 85 pages, published version, abstract added in migratio

Boundary structure and size in terms of interior and exterior harmonic measures in higher dimensions

In this work we introduce the use of powerful tools from geometric measure theory (GMT) to study problems related to the size and structure of sets of mutual absolute continuity for the harmonic measure $\omega^+$ of a domain $\Omega=\Omega^+\subset\mathbb{R}^n$ and the harmonic measure $\omega^-$ of $\Omega^-$, $\Omega^-=$int$(\Omega^c)$, in dimension $n\ge 3$

Fast inactivation in Shaker K+ channels. Properties of ionic and gating currents.

Fast inactivating Shaker H4 potassium channels and nonconducting pore mutant Shaker H4 W434F channels have been used to correlate the installation and recovery of the fast inactivation of ionic current with changes in the kinetics of gating current known as "charge immobilization" (Armstrong, C.M., and F. Bezanilla. 1977. J. Gen. Physiol. 70:567-590.). Shaker H4 W434F gating currents are very similar to those of the conducting clone recorded in potassium-free solutions. This mutant channel allows the recording of the total gating charge return, even when returning from potentials that would largely inactivate conducting channels. As the depolarizing potential increased, the OFF gating currents decay phase at -90 mV return potential changed from a single fast component to at least two components, the slower requiring approximately 200 ms for a full charge return. The charge immobilization onset and the ionic current decay have an identical time course. The recoveries of gating current (Shaker H4 W434F) and ionic current (Shaker H4) in 2 mM external potassium have at least two components. Both recoveries are similar at -120 and -90 mV. In contrast, at higher potentials (-70 and -50 mV), the gating charge recovers significantly more slowly than the ionic current. A model with a single inactivated state cannot account for all our data, which strongly support the existence of "parallel" inactivated states. In this model, a fraction of the charge can be recovered upon repolarization while the channel pore is occupied by the NH2-terminus region

Medios técnico-tácticos colectivos en boloncesto en categorías de formación

The objectives of this study were: a) record the view of basketball coaches on how they should evolve along the different stages of training, some Basic Tactical Media Collective (MTCBs), b) recording the views of basketball coaches on how to evolve along different stages of training some Complex Tactical Media Collective (MTCC). A questionnaire was administered to 102 coaches. The most significant results indicated that: a) formation increases with age, it is necessary to devote more time to MTCBs except to pass and progression, which should hold in the infant category, b) in the category minibasket and children, only develop MTCBs Pass and Progression and Establishment of the Odd, c) blocks begin to be important in the cadet category, d) development of counter-attack, followed by individual collective defense dominated in all categories, e) in the categories minibasket and children, he devotes little importance only to the collective defense and counterattack individual f) from the cadet category, when it puts more emphasis on improving the positional attack, g) is only dedicated to the importance zonal defense, from the junior category, and g) in all categories, it gives more importance to collective defense, which improved positional attack.Los objetivos del presente estudio fueron: a) registrar la opinión de entrenadores de baloncesto sobre cómo deben evolucionar a lo largo de las diferentes etapas de formación, algunos Medios Técnico-tácticos Colectivos Básicos (MTCBs); b) registrar la opinión de entrenadores de baloncesto sobre cómo deben evolucionar a lo largo de las diferentes etapas de formación algunos Medios Técnico-tácticos Colectivos Complejos (MTCC). Se administró un cuestionario a 102 entrenadores. Los resultados más significativos indicaron que: a) con forme incrementa la edad, es necesario dedicar más tiempo a los MTCBs, salvo al pase y progresión, que debe estar afianzando en la categoría infantil; b) en la categoría minibasket e infantil, únicamente se desarrollan los MTCBs de Pase y Progresión y Fijación del Impar; c) los bloqueos empiezan a tener importancia en la categoría cadete; d) el desarrollo del contraataque, seguido de la defensa colectiva individual, predomina en todas las categorías; e) en las categorías minibasket e infantil, apenas se le dedica importancia solo al contraataque y a la defensa colectiva individual; f) a partir de la categoría cadete, es cuando se le dedica más importancia a la mejora del ataque posicional; g) sólo se le dedica importancia a la defensa colectiva zonal, a partir de la categoría júnior; y g) en todas las categorías, se le aporta más importancia a la defensas colectivas, que a la mejora del ataque posicional

Fast nucleon emission as a probe of the isospin momentum dependence

In this article we investigate the structure of the non-local part of the symmetry term, that leads to a splitting of the effective masses of protons and neutrons in asymmetric matter. Based on microscopic transport simulations we suggest some rather sensitive observables in collisions of neutron-rich (unstable) ions at intermediate ($RIA$) energies. In particular we focus the attention on pre-equilibrium nucleon emissions. We discuss interesting correlations between the N/Z content of the fast emitted particles and their rapidity or transverse momentum, that show a nice dependence on the prescription used for the effective mass splitting.Comment: 5 pages, 6 figures, revtex

Comparative Analysis of Two Cryogenic Force Balance Calibration Systems

Cryogenic wind-tunnel facilities face unique challenges in the calibration and operation of various measurement systems and instrumentation. Instruments that are subjected to the cryogenic conditions of the test plenum require careful design and calibration procedures to maintain instrument performance. NASAs National Transonic Facility (NTF) and the European Transonic Windtunnel (ETW) are two cryogenic wind-tunnel facilities, each with the ability to calibrate force measurement systems (FMS) at cryogenic conditions. These facilities have different methodologies and processes for calibrating these systems. This paper discusses differences in the methodologies and processes and compares the results of two separate cryogenic calibrations of the NTF-118A force balance that were completed at both wind-tunnel facilities

Consideration of the Mechanisms for Tidal Bore Formation in an Idealized Planform Geometry

A tidal bore is a positive wave traveling upstream along the estuary of a river, generated by a relatively rapid rise of the tide, often enhanced by the funneling shape of the estuary. The swell produced by the tide grows and its front steepens as the flooding tide advances inland, promoting the formation of a sharp front wave, i.e., the tidal bore. Because of the many mechanisms and conditions involved in the process, it is difficult to formulate an effective criterion to predict the bore formation. In this preliminary analysis, aimed at bringing out the main processes and parameters that control tidal bore formation, the degrees of freedom of the problem are largely reduced by considering a rectangular channel of constant width with uniform flow, forced downstream by rising the water level at a constant rate. The framework used in this study is extremely simple, yet the problem is still complex and the solution is far from being trivial. From the results of numerical simulations, three distinctive behaviors emerged related to conditions in which a tidal bore forms, a tidal bore does not form, and a weak bore forms; the latter has a weakly steep front and after the bore formed it rapidly vanishes. Based on these behaviors, some criteria to predict the bore formation are proposed and discussed. The more effective criterion, suitably rearranged, is checked against data from real estuaries and the predictions are found to compare favorably with the available data