In this paper we give various equivalent characterizations of upper estimates of heat kernels of regular, conservative and local Dirichlet forms on doubling spaces, from both the analytic and probabilistic points of view. The first part of this paper uses purely analytic arguemtn, while the second part focuses on the probabilistic aspects where the exit time plays an important role.

Luminescence refrigeration in semiconductors is studied using a model that includes the rate equations for carriers and photons as well as the influence of spectral dependent photon recycling. Expressions are derived for cooling efficiency, cooling power density, and the minimum external quantum efficiency required for cooling. These results show that net cooling is accessible and that photon r...

This paper introduces a new chemically-assisted mechanical refrigeration system that combines the advantages of the vapor compression, vapor absorption, and refrigeration/solvent resorption systems. Principles of the new system are presented and the search for suitable refrigerant/solvent pairs for the system is discussed. The feasibility of the proposed system has been verified by a sample cal...

In the psychological refractory period (PRP) paradigm, two unmasked targets are presented, each of which requires a speeded response. Response times to the second target (T2) are slowed when T2 is presented shortly after the first target (T1). Electrophysiological studies have previously shown that the P3 event-related potential component is not delayed during T2 response slowing in the PRP par...

Psychologists often dismiss introspection as an inappropriate measure, yet subjects readily volunteer detailed descriptions of the time and effort that they spent on a task. Are such reports really so inaccurate? We asked subjects to perform a psychological refractory period experiment followed by extensive quantified introspection. On each trial, just after their objective responses, subjects ...

Psychological research has documented again and again marked performance decrements whenever humans perform 2 or more tasks at the same time. In fact, the available evidence seems to suggest that any type of behavior is subject to such limitations. The present experiments employed the psychological refractory period (PRP) paradigm to identify a clear exception to this rule: Unconditioned reflex...