437 research outputs found
A1C and Diabetes Diagnosis Among Filipino Americans, Japanese Americans, and Native Hawaiians
The Barrier Method: A Technique for Calculating Very Long Transition Times
In many dynamical systems there is a large separation of time scales between
typical events and "rare" events which can be the cases of interest. Rare-event
rates are quite difficult to compute numerically, but they are of considerable
practical importance in many fields: for example transition times in chemical
physics and extinction times in epidemiology can be very long, but are quite
important. We present a very fast numerical technique that can be used to find
long transition times (very small rates) in low-dimensional systems, even if
they lack detailed balance. We illustrate the method for a bistable
non-equilibrium system introduced by Maier and Stein and a two-dimensional (in
parameter space) epidemiology model.Comment: 20 pages, 8 figure
Computation of nucleation of a non-equilibrium first-order phase transition using a rare-event algorithm
We introduce a new Forward-Flux Sampling in Time (FFST) algorithm to
efficiently measure transition times in rare-event processes in non-equilibrium
systems, and apply it to study the first-order (discontinuous) kinetic
transition in the Ziff-Gulari-Barshad model of catalytic surface reaction. The
average time for the transition to take place, as well as both the spinodal and
transition points, are clearly found by this method.Comment: 12 pages, 10 figure
Characterization of adenomas and metastases in the adrenals: comparison between spin-echo sequences and Gd-DTPA enhanced dynamic studies.
Renormalization group crossover in the critical dynamics of field theories with mode coupling terms
Motivated by the collective behavior of biological swarms, we study the critical dynamics of field theories with coupling between order parameter and conjugate momentum in the presence of dissipation. Under a fixed-network approximation, we perform a dynamical renormalization group calculation at one loop in the near-critical disordered region, and we show that the violation of momentum conservation generates a crossover between an unstable fixed point, characterized by a dynamic critical exponent z=d/2, and a stable fixed point with z=2. Interestingly, the two fixed points have different upper critical dimensions. The interplay between these two fixed points gives rise to a crossover in the critical dynamics of the system, characterized by a crossover exponent Īŗ=4/d. The crossover is regulated by a conservation length scale R0, given by the ratio between the transport coefficient and the effective friction, which is larger as the dissipation is smaller: Beyond R0, the stable fixed point dominates, while at shorter distances dynamics is ruled by the unstable fixed point and critical exponent, a behavior which is all the more relevant in finite-size systems with weak dissipation. We run numerical simulations in three dimensions and find a crossover between the exponents z=3/2 and z=2 in the critical slowdown of the system, confirming the renormalization group results. From the biophysical point of view, our calculation indicates that in finite-size biological groups mode coupling terms in the equation of motion can significantly change the dynamical critical exponents even in the presence of dissipation, a step toward reconciling theory with experiments in natural swarms. Moreover, our result provides the scale within which fully conservative Bose-Einstein condensation is a good approximation in systems with weak symmetry-breaking terms violating number conservation, as quantum magnets or photon gases
Long COVID in Children and Adolescents
Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) has caused significant mortality and morbidity worldwide. In children, the acute SARS-CoV-2 infection is often asymptomatic or paucisymptomatic, and life-threatening complications are rare. Nevertheless, there are two long-term consequences of SARS-CoV-2 infection in children that raise concern: multisystem inflammatory syndrome in children (MIS-C) and long COVID. While the understanding and the experience regarding the acute phase of SARS-CoV-2 infection have remarkably increased over time, scientific and clinical research is still exploring the long-term effects of COVID-19. In children, data on long COVID are scant. Reports are conflicting regarding its prevalence, duration and impact on daily life. This narrative review explored the latest literature regarding long COVID-19 in the pediatric population. We showed that long COVID in children might be a relevant clinical problem. In most cases, the prognosis is good, but some children may develop long-term symptoms with a significant impact on their daily life. The paucity of studies on long COVID, including a control group of children not infected by SARS-CoV-2, prevents us from drawing firm conclusions. Whether the neuropsychiatric symptoms widely observed in children and adolescents with long COVID are the consequence of SARS-CoV-2 infection or are due to the tremendous stress resulting from the restrictions and the pandemics is still not clear. In both cases, psychological support can play a fundamental role in managing COVID pandemics in children. More knowledge is needed to share a standardized definition of the syndrome and improve its management and treatment
Catheter-tissue contact force values do not impact mid-term clinical outcome following pulmonary vein isolation in patients with paroxysmal atrial fibrillation.
Alignment of the high beta magnets in the RHIC interaction regions
The betatron functions inside the triplet quadrupoles in the Relativistic Heavy Ion Collider-RHIC are of the order of 1,500 m, necessitating additional attention in the alignment procedure. On each side of the interaction regions eight cryogenic elements (six quadrupoles and two horizontal bending dipoles) are placed inside large cryostats. The quadrupole magnetic centers are obtained by antenna measurements with an accuracy of {+-} 60 {micro}m. The signals from the antenna were cross calibrated with the colloidal cell measurements of the same magnet. The positions of the fiducials are related to the magnet centers during the antenna measurements. Elements are positioned warm inside the cryostats, with offsets to account for shrinkage during the cool down. The supports at the middle of the two central quadrupoles are fixed, while every other element slides longitudinally inside the cryostat during cool down or warm up
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