Bremsstrahlung Spectrum in alpha Decay

Using our previous approach to electromagnetic emission during tunneling, an explicit, essentially classical, formula describing the bremsstrahlung spectrum in alpha decay is derived. The role of tunneling motion in photon emission is discussed. The shape of the spectrum is a universal function of the ratio Eg/Eo , where Eg is the photon energy and Eo is a characteristic energy depending only on the nuclear charge and the energy of the alpha particle.Comment: 8 pages, 3 figure

Entanglement dynamics in superconducting qubits affected by local bistable impurities

We study the entanglement dynamics for two independent superconducting qubits, each affected by a bistable impurity generating random telegraph noise (RTN) at pure dephasing. The relevant parameter is the ratio g between the qubit–RTN coupling strength and the RTN switching rate, which captures the physics of the crossover between Markovian and non-Markovian features of the dynamics. For identical qubit–RTN subsystems, a threshold value gth of the crossover parameter separates exponential decay and the onset of revivals; different qualitative behaviors also show up by changing the initial conditions of the RTN. We also show that, for different qubit–RTN subsystems, when both qubits are very strongly coupled to the RTN, an increase of entanglement revival amplitude may occur during the dynamics

Dynamical suppression of telegraph and 1/f noise due to quantum bistable fluctuator

We study dynamical decoupling of a qubit from non gaussian quantum noise due to discrete sources, as bistable fluctuators and 1/f noise. We obtain analytic and numerical results for generic operating point. For very large pulse frequency, where dynamic decoupling compensates decoherence, we found universal behavior. At intermediate frequencies noise can be compensated or enhanced, depending on the nature of the fluctuators and on the operating point. Our technique can be applied to a larger class of non-gaussian environments.Comment: Revtex 4, 5 pages, 3 figures. Title revised and some other minor changed. Final version as published in PR

Dielectric spectroscopy of water at low frequencies: The existence of an isopermitive point

We have studied the real part of the dielectric constant of water from 100 Hz to 1 MHz. We have found that there is a frequency where the dielectric constant is independent of temperature, and called this the isopermitive point. Below this point the dielectric constant increases with temperature, above, it decreases. To understand this behavior, we consider water as a system of two species: ions and dipoles. The first give rise to the so called Maxwell-Wagner-Sillars effect, the second obey the Maxwell-Boltzmann statistics. At the isopermitive point the effect of both mechanisms in the dielectric response compensate each other.Comment: 4 pages, 4 figures, submitted to Chem. Phys. Let

Qubits as devices to detect the third moment of current fluctuations

Under appropriate conditions controllable two-level systems can be used to detect the third moment of current fluctuations. We derive a Master Equation for a quantum system coupled to a bath valid to the third order in the coupling between the system and the environment. In this approximation the reduced dynamics of the quantum system depends on the frequency dependent third moment. Specializing to the case of a controllable two-level system (a qubit) and in the limit in which the splitting between the levels is much smaller than the characteristic frequency of the third moment, it is possible to show that the decay of the qubit has additional oscillations whose amplitude is directly proportional to the value of the third moment. We discuss an experimental setup where this effect can be seen.Comment: 10 pages, 7 figure

Structural and connectivity parameters reveal spared connectivity in young patients with non-progressive compared to slow-progressive cerebellar ataxia

INTRODUCTION: Within Pediatric Cerebellar Ataxias (PCAs), patients with non-progressive ataxia (NonP) surprisingly show postural motor behavior comparable to that of healthy controls, differently to slow-progressive ataxia patients (SlowP). This difference may depend on the building of compensatory strategies of the intact areas in NonP brain network. METHODS: Eleven PCAs patients were recruited: five with NonP and six with SlowP. We assessed volumetric and axonal bundles alterations with a multimodal approach to investigate whether eventual spared connectivity between basal ganglia and cerebellum explains the different postural motor behavior of NonP and SlowP patients. RESULTS: Cerebellar lobules were smaller in SlowP patients. NonP patients showed a lower number of streamlines in the cerebello-thalamo-cortical tracts but a generalized higher integrity of white matter tracts connecting the cortex and the basal ganglia with the cerebellum. DISCUSSION: This work reveals that the axonal bundles connecting the cerebellum with basal ganglia and cortex demonstrate a higher integrity in NonP patients. This evidence highlights the importance of the cerebellum-basal ganglia connectivity to explain the different postural motor behavior of NonP and SlowP patients and support the possible compensatory role of basal ganglia in patients with stable cerebellar malformation

Investigation of the impact of neutron irradiation on SiC power MOSFETs lifetime by reliability tests

High temperature reverse-bias (HTRB), High temperature gate-bias (HTGB) tests and electrical DC characterization were performed on planar-SiC power MOSFETs which survived to accelerated neutron irradiation tests carried out at ChipIr-ISIS (Didcot, UK) facility, with terrestrial neutrons. The neutron test campaigns on the SiC power MOSFETs (manufactered by ST) were con-ducted on the same wafer lot devices by STMicroelectronics and Airbus, with different neutron tester systems. HTGB and HTRB tests, which characterise gate-oxide integrity and junction robustness, show no difference between the non irradiated devices and those which survived to the neutron irradiation tests, with neutron fluence up to 2 × 1011 (n/cm2). Electrical characterization performed pre and post-irradiation on different part number of power devices (Si, SiC MOSFETs and IGBTs) which survived to neutron irradiation tests does not show alteration of the data-sheet electrical parameters due to neutron interaction with the device

Acoustic and relaxation processes in supercooled o-ter-phenyl by optical-heterodyne transient grating experiment

The dynamics of the fragile glass-forming o-ter-phenyl is investigated by time-resolved transient grating experiment with an heterodyne detection technique in a wide temperature range. We investigated the dynamics processes of this glass-former over more then 6 decades in time with an excellent signal/noise. Acoustic, structural and thermal relaxations have been clearly identify and measured in a time-frequency window not covered by previous spectroscopic investigations. A detailed comparison with the density response function, calculated on the basis of generalized hydrodynamics model, has been worked out

Bremsstrahlung in α\alpha Decay

A quantum mechanical analysis of the bremsstrahlung in $\alpha$ decay of $^{210}$Po is performed in close reference to a semiclassical theory. We clarify the contribution from the tunneling, mixed, outside barrier regions and from the wall of the inner potential well to the final spectral distribution, and discuss their interplay. We also comment on the validity of semiclassical calculations, and the possibility to eliminate the ambiguity in the nuclear potential between the alpha particle and daughter nucleus using the bremsstrahlung spectrum.Comment: 6 pages, 3 figures, submitted to PR

Integrating demand uncertainty in inventory routing for recyclable waste collection

Osteoblast cell adhesion to the extracellular matrix is established through two main pathways: one is mediated by the binding between integrin and a minimal adhesion sequence (RGD) on the extracellular protein, the other is based on the interactions between transmembrane proteoglycans and heparin-binding sequences found in many matrix proteins. The aim of this study is the evaluation in an in vivo endosseous implant model of the early osteogenic response of the peri-implant bone to a biomimetic titanium surface functionalized with the retro-inverso 2DHVP peptide, an analogue of Vitronectin heparin binding site. The experimental plan is based on a bilateral study design of Control and 2DHVP implants inserted respectively in the right and left femur distal metaphysis of adult male Wistar rats (n=16) weighing about 300 gr and evaluated after 15 days. Fluorochromic bone vital markers, were given at specific time frame, in order to monitor the dynamic of new bone deposition. The effect inducted by the peptidomimetic coating on the surrounding bone were qualitatively and quantitatively evaluated by means of static and dynamic histomorphometric analyses performed within three concentric and subsequent circular Regions of Interest (ROI) of equivalent thickness (220 μm), ROI1 adjacent to the interface, ROI2, the middle, and ROI3 the farthest. The data indicated that these functionalized implants stimulated a higher bone apposition rate (p<0,01) and larger and rapid osteoblast activation in terms of mineralising surface within ROI1 compared to the Control (p<0,01). These higher osteoblast recruitment and activation leads to a greater bone to implant contact reached for DHVP samples (p<0,5). This represents an initial stimulus of the osteogenic activity that might results in a faster and better osteointegration process