Effect of hybridization on the magnetic properties of correlated two-band metals

The magnetic properties of transition-like metals are discussed within the single site approximation, which is a picture to take into account electron correlations. The metal is described by two hybridized bands one of which includes Coulomb correlation. The presented results indicate that ferromagnetism arises for adequate values of hybridization (V), correlation (U) and occupation number($n_{\sigma}$). Some similarities with Dynamical Mean-Field Theory (DMFT) are indicated.Comment: 3 pages, 3 figures, presented at the 53rd MMM08 conference in Austin, 200

Scaling laws for the decay of multiqubit entanglement

We investigate the decay of entanglement of generalized N-particle Greenberger-Horne-Zeilinger (GHZ) states interacting with independent reservoirs. Scaling laws for the decay of entanglement and for its finite-time extinction (sudden death) are derived for different types of reservoirs. The latter is found to increase with the number of particles. However, entanglement becomes arbitrarily small, and therefore useless as a resource, much before it completely disappears, around a time which is inversely proportional to the number of particles. We also show that the decay of multi-particle GHZ states can generate bound entangled states.Comment: Minor mistakes correcte

Maintenance of Gains, Morbidity, and Mortality at 1 Year Following Cardiac Rehabilitation in a Middle‐Income Country: A Wait‐List Control Crossover Trial

Background-—Despite the epidemic of cardiovascular diseases in middle-income countries, few trials are testing the benefits of cardiac rehabilitation (CR). This trial assessed (1) maintenance of functional capacity, risk factor control, knowledge, and hearthealth behaviors and (2) mortality and morbidity at 6 months following CR in a middle-income country. Methods and Results-—Eligible Brazilian coronary patients were initially randomized (1:1:1 concealed) to 1 of 3 parallel arms (comprehensive CR [exercise plus education], exercise-only CR, or wait-list control). The CR programs were 6 months in duration, at which point follow-up assessments were performed. Mortality and morbidity were ascertained from chart and patient or family report (blinded). Controls were then offered CR (crossover). Outcomes were again assessed 6 months later (blinded). ANCOVA was performed for each outcome at 12 months. Overall, 115 (88.5%) patients were randomized, and 62 (53.9%) were retained at 1 year. At 6 months, 23 (58.9%) of those 39 initially randomized to the wait-list control elected to attend CR. Functional capacity, risk factors, knowledge, and heart-health behaviors were maintained from 6 to 12 months in participants from both CR arms (all P>0.05). At 1 year, knowledge was significantly greater with comprehensive CR at either time point (P<0.001). There were 2 deaths. Hospitalizations (P=0.03), nonfatal myocardial infarctions (P=0.04), and percutaneous coronary interventions (P=0.03) were significantly fewer with CR than control at 6 months. Conclusions-—CR participation is associated with lower morbidity, long-term maintenance of functional capacity, risk factors, and heart-health behaviors, as well as with greater cardiovascular knowledge compared with no CR. Clinical Trial Registration-—URL: http://www.clinicaltrials.gov. Unique identifier: NCT02575976. (J Am Heart Assoc. 2019;8: e011228. DOI: 10.1161/JAHA.118.011228.) Key Words: cardiac rehabilitation • coronary disease • morbidity/mortality • rehabilitation • risk factorYork University Librarie

Micromagnetic Simulations of Ferromagnetic Rings

Thin nanomagnetic rings have generated interest for fundamental studies of magnetization reversal and also for their potential in various applications, particularly as magnetic memories. They are a rare example of a geometry in which an analytical solution for the rate of thermally induced magnetic reversal has been determined, in an approximation whose errors can be estimated and bounded. In this work, numerical simulations of soft ferromagnetic rings are used to explore aspects of the analytical solution. The evolution of the energy near the transition states confirms that, consistent with analytical predictions, thermally induced magnetization reversal can have one of two intermediate states: either constant or soliton-like saddle configurations, depending on ring size and externally applied magnetic field. The results confirm analytical predictions of a transition in thermally activated reversal behavior as magnetic field is varied at constant ring size. Simulations also show that the analytic one dimensional model continues to hold even for wide rings

Wave packet dynamics and valley filter in strained graphene

The time evolution of a wavepacket in strained graphene is studied within the tight-binding model and continuum model. The effect of an external magnetic field, as well as a strain-induced pseudo-magnetic field, on the wave packet trajectories and zitterbewegung are analyzed. Combining the effects of strain with those of an external magnetic field produces an effective magnetic field which is large in one of the Dirac cones, but can be practically zero in the other. We construct an efficient valley filter, where for a propagating incoming wave packet consisting of momenta around the K and K' Dirac points, the outgoing wave packet exhibits momenta in only one of these Dirac points, while the components of the packet that belong to the other Dirac point are reflected due to the Lorentz force. We also found that the zitterbewegung is permanent in time in the presence of either external or strain-induced magnetic fields, but when both the external and strain-induced magnetic fields are present, the zitterbewegung is transient in one of the Dirac cones, whereas in the other cone the wave packet exhibits permanent spatial oscillations.Comment: 13 pages, 10 figure