Noncommutative Quantum Mechanics Viewed from Feynman Formalism

Dyson published in 1990 a proof due to Feynman of the Maxwell equations. This proof is based on the assumption of simple commutation relations between position and velocity. We first study a nonrelativistic particle using Feynman formalism. We show that Poincar\'{e}'s magnetic angular momentum and Dirac magnetic monopole are the direct consequences of the structure of the sO(3) Lie algebra in Feynman formalism. Then we show how to extend this formalism to the dual momentum space with the aim of introducing Noncommutative Quantum Mechanics which was recently the subject of a wide range of works from particle physics to condensed matter physics.Comment: 11 pages, To appear in the Proceedings of the Lorentz Workshop "Beyond the Quantum", eds. Th.M. Nieuwenhuizen et al., World Scientific, Singapore, 2007. Added reference

Effects of disorder on the vortex charge

We study the influence of disorder on the vortex charge, both due to random pinning of the vortices and due to scattering off non-magnetic impurities. In the case when there are no impurities present, but the vortices are randomly distributed, the effect is very small, except when two or more vortices are close by. When impurities are present, they have a noticeable effect on the vortex charge. This, together with the effect of temperature, changes appreciably the vortex charge. In the case of an attractive impurity potential the sign of the charge naturally changes.Comment: 10 pages, 16 figures. Accepted in Phys. Rev.

Local density of states of a strongly type-II d-wave superconductor: The binary alloy model in a magnetic field

We calculate self-consistently the local density of states (LDOS) of a d-wave superconductor considering the scattering of the quasiparticles off randomly distributed impurities and off externally induced vortices. The impurities and the vortices are randomly distributed but the vortices are preferably located near the impurities. The increase of either the impurity repulsive potential or the mpurity density only affects the density of states (DOS) slightly. The dominant effect is due to the vortex scattering. The results for the LDOS agree qualitatively with experimental results considering that most vortices are pinned at the impurities.Comment: To be published in Physical Review

Symplectic map description of Halley's comet dynamics

The main features of 1P/Halley chaotic dynamics can be described by a two dimensional symplectic map. Using Mel'nikov integral we semi-analytically determine such a map for 1P/Halley taking into account gravitational interactions from the Sun and the eight planets. We determine the Solar system kick function ie the energy transfer to 1P/Halley along one passage through the Solar system. Our procedure allows to compute for each planet its contribution to the Solar system kick function which appears to be the sum of the Keplerian potential of the planet and of a rotating circular gravitational dipole potential due to the Sun movement around Solar system barycenter. We test the robustness of the symplectic Halley map by directly integrating Newton's equations over $\sim 2.4\cdot 10^4$ yr around Y2K and by reconstructing the Solar system kick function. Our results show that the Halley map with fixed parameters gives a reliable description of comet dynamics on time scales of $10^4$ yr while on a larger scales the parameters of the map are slowly changing due to slow oscillations of orbital momentum.Comment: To be published in Physics Letter A, 8 pages, 5 figures, supplementary material at http://perso.utinam.cnrs.fr/~lages/publications/sm/sm21.htm

Phase of bi-particle localized states for the Cooper problem in two-dimensional disordered systems

The Cooper problem is studied numerically for the Anderson model with disorder in two-dimensions. It is shown that the attractive Hubbard interaction creates a phase of bi-particle localized states in the regime where non-interacting states are delocalized. This phase cannot be obtained in the mean-field approximation and the pair coupling energy is strongly enhanced in this regime. The effects of magnetic field are studied and it is shown that under certain conditions they lead to delocalization.Comment: revtex, 7 pages, 8 figure

mHealth Applications to Monitor Lifestyle Behaviors and Circadian Rhythm in Clinical Settings: Current Perspective and Future Directions

Metabolic diseases are a global rising health burden, mainly due to the deleterious interaction of current lifestyles with the underlying biology of these diseases. Daily habits and behaviors, such as diet, sleep, and physical exercise impact the whole-body circadian system through the synchronization of the peripheral body clocks that contribute to metabolic homeostasis. The disruption of this system may promote the development of metabolic diseases, including obesity and diabetes, emphasizing the importance of assessing and monitoring variables that affect circadian rhythms. Advances in technology are generating innovative resources and tools for health care management and patient monitoring, particularly important for chronic conditions. The use of mobile health technologies, known as mHealth, is increasing and these approaches are contributing to aiding both patients and healthcare professionals in disease management and education. The mHealth solutions allow continuous monitoring of patients, sharing relevant information and data with physicians and other healthcare professionals and accessing education resources to support informed decisions. Thus, if properly used, these tools empower patients and help them to adopt healthier lifestyles. This article aims to give an overview of the influence of circadian rhythms disruption and lifestyle habits in the progression of metabolic diseases while also reviewing some of the mobile applications available to monitor lifestyle behaviors and individual chronobiology. Herein is also described the design and development of the NutriClock system, an mHealth solution developed by our team to monitor these variables

CO2 Flushing Triggers Paroxysmal Eruptions at Open Conduit Basaltic Volcanoes

Open conduit volcanoes erupt with the highest frequency on Earth. Their activity is characterized by an outgassing flux that largely exceeds the gas that could be released by the erupted magma; and by frequent small explosions intercalated by larger events that pose a significant risk to locals, tourists, and scientists. Thus, identifying the signs of an impending larger explosion is of utmost importance for the mitigation of volcanic hazard. Larger explosive events have been associated with the sudden ascent of volatile rich magmas, however, where and why magma accumulates within the plumbing system remains unclear. Here we show that the interaction between CO2-rich fluids and magma spontaneously leads to the accumulation of volatile-rich, low density and gravitationally unstable magma at depth, without the requirement of permeability barriers. CO2-flushing forces the exsolution of water and the increase of magma viscosity, which proceeds from the bottom of the magma column upward. This rheological configuration unavoidably leads to the progressive thickening of a gas-rich and low density (i.e., gravitationally unstable) layer at the bottom of the feeding system. Our calculations account for observations, gas monitoring and petrological data; moreover, they provide a basis to trace the approach to deeply triggered large or paroxysmal eruptions and estimate their size from monitoring data. Our model is finally applied to Stromboli volcano, an emblematic example of open conduit volcano, but can be applied to any other open conduit volcano globally and offers a framework to anticipate the occurrence of unexpectedly large eruptions

Suppression of quantum chaos in a quantum computer hardware

We present numerical and analytical studies of a quantum computer proposed by the Yamamoto group in Phys. Rev. Lett. 89, 017901 (2002). The stable and quantum chaos regimes in the quantum computer hardware are identified as a function of magnetic field gradient and dipole-dipole couplings between qubits on a square lattice. It is shown that a strong magnetic field gradient leads to suppression of quantum chaos.Comment: 8 pages, 8 figures, research done at http://www.quantware.ups-tlse.fr

Crustal controls on light noble gas isotope variability along the andean volcanic arc

This study combines new noble gas data from fluid inclusions in minerals from Sabancaya, Ubinas, and El Misti (CVZ, Peru) and Villarica (South Chile, SVZ) with a revised noble gas compilation in the Andes, to identify systematic along arc variations in helium isotope compositions. We find 3He/4He ratios varying from 8.8 RA (Colombia) to 7.4 RA (Ecuador) within the NVZ, and only as high as 6.4 RA in the CVZ (RA is the atmospheric 3He/4He ratio of 1.39 × 10-6). These distinct isotope compositions cannot be explained by variable radiogenic 4He production via slab fluid transport of U and Th in the mantle wedge, since both NVZ and CVZ share similar slab sediment inputs (Th/La ≈ 0.08-0.13). Instead, the progressively more radiogenic 3He/4He signatures in Ecuador and Peru reflect 4He addition upon magma ascent/ storage in the crust, this being especially thick in Peru (>70 km) and Ecuador (>50 km) relative to Colombia (∼30-45 km). The intermediate compositions in the North (8.0 RA) and South (7.9 RA) Chile, both high sediment flux margins, mostly reflect a more efficient delivery of radiogenic He in the wedge from the subducted (U-Th-rich) terrigenous sediments. Our results bring strong evidence for the major role played by crustal processes in governing noble gas compositions along continental arcs