Low-energy diffraction; a direct-channel point of view: the background

We argue that at low-energies, typical of the resonance region, the contribution from direct-channel exotic trajectories replaces the Pomeron exchange, typical of high energies. A dual model realizing this idea is suggested. While at high energies it matches the Regge pole behavior, dominated by a Pomeron exchange, at low energies it produces a smooth, structureless behavior of the total cross section determined by a direct-channel nonlinear exotic trajectory, dual to the Pomeron exchange.Comment: 6 pages, 1 figure. Talk presented at the Second International "Cetraro" Workshop & NATO Advanced Research Workshop "Diffraction 2002", Alushta, Crimea, Ukraine, August 31 - September 6, 200

The Harari-Shupe preon model and nonrelativistic quantum phase space

We propose that the whole algebraic structure of the Harari-Shupe rishon model originates via a Dirac-like linearization of quadratic form x^2+p^2, with position and momentum satisfying standard commutation relations. The scheme does not invoke the concept of preons as spin-1/2 subparticles, thus evading the problem of preon confinement, while fully explaining all symmetries emboded in the Harari-Shupe model. Furthermore, the concept of quark colour is naturally linked to the ordering of rishons. Our scheme leads to group U(1)xSU(3) combined with SU(2), with two of the SU(2) generators not commuting with reflections. An interpretation of intra-generation quark-lepton transformations in terms of genuine rotations and reflections in phase space is proposed

On Estimating the Flux of the Brightest Cosmic Ray Source above 57x10^18 eV

The sources of ultra-high energy cosmic rays are not yet known. However, the discovery of anisotropic cosmic rays above 57x10^18 eV by the Pierre Auger Observatory suggests that a direct source detection may soon be possible. The near-future prospects for such a measurement are heavily dependent on the flux of the brightest source. In this work, we show that the flux of the brightest source above 57x10^18 eV is expected to comprise 10% or more of the total flux if two general conditions are true. The conditions are: 1.) the source objects are associated with galaxies other than the Milky Way and its closest neighbors, and 2.) the cosmic ray particles are protons or heavy nuclei such as iron and the Greisen-Zatsepin-Kuz'min effect is occurring. The Pierre Auger Observatory collects approximately 23 events above 57x10^18 eV per year. Therefore, it is plausible that, over the course of several years, tens of cosmic rays from a single source will be detected.Comment: 10 pages, 2 figures, submitted to Astrophysical Journal Letter

Lensing of ultra-high energy cosmic rays in turbulent magnetic fields

We consider the propagation of ultra high energy cosmic rays through turbulent magnetic fields and study the transition between the regimes of single and multiple images of point-like sources. The transition occurs at energies around $E_c\simeq Z~41 {\rm EeV}(B_{rms}/5 \mu{\rm G}) (L/ 2 {\rm kpc})^{3/2}\sqrt{50 {\rm pc}/L_c}$, where $L$ is the distance traversed by the CR's with electric charge $Ze$ in the turbulent magnetic field of root mean square strength $B_{rms}$ and coherence length $L_c$. We find that above $2 E_c$ only sources located in a fraction of a few % of the sky can reach large amplifications of its principal image or start developing multiple images. New images appear in pairs with huge magnifications, and they remain amplified over a significant range of energies. At decreasing energies the fraction of the sky in which sources can develop multiple images increases, reaching about 50% for $E>E_c/2$. The magnification peaks become however increasingly narrower and for $E<E_c/3$ their integrated effect becomes less noticeable. If a uniform magnetic field component is also present it would further narrow down the peaks, shrinking the energy range in which they can be relevant. Below $E\simeq E_c/10$ some kind of scintillation regime is reached, where many demagnified images of a source are present but with overall total magnification of order unity. We also search for lensing signatures in the AGASA data studying two-dimensional correlations in angle and energy and find some interesting hints.Comment: 30 pages, 16 figures, final version with minor change

Axions from wall decay

We discuss the decay of axion walls bounded by strings and present numerical simulations of the decay process. In these simulations, the decay happens immediately, in a time scale of order the light travel time, and the average energy of the radiated axions is $\simeq 7 m_a$ for $v_a/m_a\simeq 500$. $$ is found to increase approximately linearly with $\ln(v_a/m_a)$. Extrapolation of this behaviour yields $\simeq 60 m_a$ in axion models of interest.Comment: 6 pages, 7 figures, to be published in the Proc. of the 5th IFT Axion workshop Gainesville FL, Mar 13-15 199

Clinical Medicine and Clinical Trials

The author discusses the role of clinical trials in clinical medicine

Early consensus management for non-ICU acute respiratory failure SARS-CoV-2 emergency in Italy : from ward to trenches

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Exercise-induced cardiac costraint by the lungs

A patient of fourty-five years old male, with severe emphysema, underwent bullectomy. He was studied, before and one year after surgery, by standard pulmonary function test and cardiopulmonary exercise test. We found that before bullectomy, tidal volume increases up to 45 W and flattens thereafter. After bullectomy tidal volume increases trough the entire exercise

Weak-Lensing by Large-Scale Structure and the Polarization Properties of Distant Radio-Sources

We estimate the effects of weak lensing by large-scale density inhomogeneities and long-wavelength gravitational waves upon the polarization properties of electromagnetic radiation as it propagates from cosmologically distant sources. Scalar (density) fluctuations do not rotate neither the plane of polarization of the electromagnetic radiation nor the source image. They produce, however, an appreciable shear, which distorts the image shape, leading to an apparent rotation of the image orientation relative to its plane of polarization. In sources with large ellipticity the apparent rotation is rather small, of the order (in radians) of the dimensionless shear. The effect is larger at smaller source eccentricity. A shear of 1% can induce apparent rotations of around 5 degrees in radio sources with the smallest eccentricity among those with a significant degree of integrated linear polarization. We discuss the possibility that weak lensing by shear with rms value around or below 5% may be the cause for the dispersion in the direction of integrated linear polarization of cosmologically distant radio sources away from the perpendicular to their major axis, as expected from models for their magnetic fields. A rms shear larger than 5% would be incompatible with the observed correlation between polarization properties and source orientation in distant radio galaxies and quasars. Gravity waves do rotate both the plane of polarization as well as the source image. Their weak lensing effects, however, are negligible.Comment: 23 pages, 2 eps figures, Aastex 4.0 macros. Final version, as accepted by ApJ. Additional references and some changes in the introduction and conclusion

Static Gravitational Global Monopoles

Static solutions in spherical symmetry are found for gravitating global monopoles. Regular solutions lacking a horizon are found for $\eta < 1/\sqrt{8\pi}$, where $\eta$ is the scale of symmetry breaking. Apparently regular solutions with a horizon are found for 1/\sqrt{8\pi} \le \eta \alt \sqrt{3/8\pi}. Though they have a horizon, they are not Schwarzschild. The solution for $\eta = 1/\sqrt{8\pi}$ is argued to have a horizon at infinity. The failure to find static solutions for $\eta > \sqrt{3/8\pi} \approx 0.3455$ is consistent with findings that topological inflation begins at $\eta \approx 0.33$.Comment: 4 pages, 6 figure