1,998 research outputs found
Theory of Q-degradation and nonlinear effects in Nb-coated superconducting cavities
Amplitude-dependent absorption of RF power in superconducting cavity with a wall of normal metal (Cu ) covered by a film of superconductor (Nb ) is determined by three factors: (1)depairing effect of high-current density on superconducting energy gap; (2)increase of electromagnetic power penetrating to normal metal and Drude-absorbed in it, at higher RF amplitude; (3)heating of both superconducting coating and normal substrate resulting in increase of quasiparticle excitation density at higher RF power (P). Cavity Q-factor is calculated as a hnction of RF amplitude A = fi and is shown to follow a relationship 1n(Q/ Q,) = -const-P" with a=l at low temperature T T* where T* is characteristic temperature T* X TcS I d, S is the London penetration depth and d the thickness of superconducting coating
Human Motion Trajectory Prediction: A Survey
With growing numbers of intelligent autonomous systems in human environments,
the ability of such systems to perceive, understand and anticipate human
behavior becomes increasingly important. Specifically, predicting future
positions of dynamic agents and planning considering such predictions are key
tasks for self-driving vehicles, service robots and advanced surveillance
systems. This paper provides a survey of human motion trajectory prediction. We
review, analyze and structure a large selection of work from different
communities and propose a taxonomy that categorizes existing methods based on
the motion modeling approach and level of contextual information used. We
provide an overview of the existing datasets and performance metrics. We
discuss limitations of the state of the art and outline directions for further
research.Comment: Submitted to the International Journal of Robotics Research (IJRR),
37 page
Malignant hypertension and hyperreninemia: Primary or secondary hypertension? A case report
Malignant hypertension is a rare condition characterized by severe hypertension and multi-organ ischemic damage. Marked activation of the renin-angiotensin system is observed in many patients, but its persistence over time is not known. We report a case of a 42-year-old woman who presented with severe hypertension and multi-organ damage. Initial evaluation showed an elevated value of direct renin concentration with normal plasma aldosterone concentration and a nodular lesion in the left adrenal gland. The differential diagnosis between the primary and secondary form of hypertension had to be questioned. Consequently, the patient was followed up for 20 months. Repeated checks showed a significant increase in renin levels with a normal aldosterone concentration and regression of organ damage. After 20 months, renin values returned within normal range. Hyperreninemia persisting over a long period of time has not been fully explained. Long-term follow-up allowed us to attribute malignant hypertension to de novo essential hypertension
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