University of South Carolina

About: University of South Carolina is a education organization based out in Columbia, South Carolina, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 25792 authors who have published 59995 publications receiving 2246122 citations. The organization is also known as: USC & U.S.C..

Memory effects in complex materials and nanoscale systems

Abstract: Memory effects are ubiquitous in nature and are particularly relevant at the nanoscale where the dynamical properties of electrons and ions strongly depend on the history of the system, at least within certain time scales. We review here the memory properties of various materials and systems which appear most strikingly in their non-trivial, time-dependent resistive, capacitative and inductive characteristics. We describe these characteristics within the framework of memristors, memcapacitors and meminductors, namely memory-circuit elements with properties that depend on the history and state of the system. We examine basic issues related to such systems and critically report on both theoretical and experimental progress in understanding their functionalities. We also discuss possible applications of memory effects in various areas of science and technology ranging from digital to analog electronics, biologically inspired circuits and learning. We finally discuss future research opportunities in the field.

Possible mechanisms of central nervous system fatigue during exercise.

Abstract: Fatigue of voluntary muscular effort is a complex phenomenon. To date, relatively little attention has been placed on the role of the central nervous system (CNS) in fatigue during exercise despite the fact that the unwillingness to generate and maintain adequate CNS drive to the working muscle is the most likely explanation of fatigue for most people during normal activities. Several biological mechanisms have been proposed to explain CNS fatigue. Hypotheses have been developed for several neurotransmitters including serotonin (5-HT; 5-hydroxytryptamine), dopamine, and acetylcholine. The most prominent one involves an increase in 5-HT activity in various brain regions. Good evidence suggests that increases and decreases in brain 5-HT activity during prolonged exercise hasten and delay fatigue, respectively, and nutritional manipulations designed to attenuate brain 5-HT synthesis during prolonged exercise improve endurance performance. Other neuromodulators that may influence fatigue during exercise include cytokines and ammonia. Increases in several cytokines have been associated with reduced exercise tolerance associated with acute viral or bacterial infection. Accumulation of ammonia in the blood and brain during exercise could also negatively effect the CNS function and fatigue. Clearly fatigue during prolonged exercise is influenced by multiple CNS and peripheral factors. Further elucidation of how CNS influences affect fatigue is relevant for achieving optimal muscular performance in athletics as well as everyday life.

Eliciting individual discount rates

Abstract: Controlled laboratory conditions using monetary incentives have been utilized in previous studies that examine individual discount rates, and researchers have found several apparently robust anomalies. We conjecture that subject behavior in these experiments may be affected by (uncontrolled) factors other than discount rates. We address some experimental design issues and report a new series of experiments designed to elicit individual discount rates. Our primary treatments include: (i) informing subjects of the annual and effective interest rates associated with alternative payment streams, and (ii) informing subjects of current market interest rates. We also test for the effect of real (vs. hypothetical) payments and for the effect of delaying both payment options (vs. offering an immediate payment option). The statistical analysis uses censored data techniques to account for the interactions between field and lab incentives. Each of the information treatments appears to reduce revealed discount rates. When both types of information are provided, annual rates in the interval of 15%–17.5% are revealed, whereas rates of 20%–25% are revealed in the control session. Each of the treatments also lowers the residual variance of subject responses.