Research on physical and physiological aspects of visual optics in space flight

Physical and physiological aspects of visual optics in space fligh

Resonant tunneling transistors with controllable negative differential resistances

Three-terminal devices based on resonant tunneling through two quantum barriers separated by a quantum well are presented and analyzed theoretically. Each proposed device consists of a resonant tunneling double barrier heterostructure integrated with a Schottky barrier field-effect transistor configuration. The essential feature of these devices is the presence, in their output current-voltage (I_{D} - V_{D}) curves, of negative differential resistances controlled by a gate voltage. Because of the high-speed characteristics associated with tunnel structures, these devices could find applications in tunable millimeter-wave oscillators, negative resistance amplifiers, and high-speed digital circuits

Characterizing Entanglement Sources

We discuss how to characterize entanglement sources with finite sets of measurements. The measurements do not have to be tomographically complete, and may consist of POVMs rather than von Neumann measurements. Our method yields a probability that the source generates an entangled state as well as estimates of any desired calculable entanglement measures, including their error bars. We apply two criteria, namely Akaike's information criterion and the Bayesian information criterion, to compare and assess different models (with different numbers of parameters) describing entanglement-generating devices. We discuss differences between standard entanglement-verificaton methods and our present method of characterizing an entanglement source.Comment: This submission, together with the next one, supersedes arXiv:0806.416

Perceptions of telemedicine and costs incurred by a visit to a general infectious diseases clinic: A survey

Background: The costs of attending in-person general infectious diseases clinics and preferences for visit type (telemedicine vs in-person) are not well known. We aimed to measure the time-related, monetary, social, and societal costs associated with travel to an in-person clinic visit and to assess patients\u27 preferences, questions, and concerns regarding telemedicine. Methods: Patients (≥18 years, living ≥25 miles from clinic at time of clinic visit) were recruited for this survey study from the general infectious diseases (ID) clinic at Washington University from June 2019 to February 2020. We calculated time and money potentially saved by telemedicine, as well as carbon dioxide emissions, with the assistance of Google Maps (low/high estimates). We also determined patient preferences regarding telemedicine for ID care. Results: Seventy-five patients completed the study. The round-trip mean travel distance was 227.2 ± 142.6 miles, mean travel time was 3.6 ± 2.0 hours to 4.5 ± 2.3 hours (low and high estimates from Google Maps), travel costs were $131.34 ±$82.27, and mean carbon dioxide emissions were 91.79 ± 57.60 kg. Fifty-eight patients (77.3%) said they would be willing to have a telemedicine visit in the future, and 30 (40.5%) said they would rather have had their visit the day the survey was completed as a telemedicine visit. Conclusions: Telemedicine has the potential to significantly reduce patient costs, both monetary and time-related, and offers substantial environmental benefits, while being an acceptable method of care delivery to most patients at a general ID clinic

Evaluation of the BioFire FilmArray pneumonia panel for detection of viral and bacterial pathogens in lower respiratory tract specimens in the setting of a tertiary care academic medical center

Our objective was to evaluate the diagnostic yield and accuracy of the BioFire FilmArray pneumonia panel (BFPP) for identification of pathogens in lower respiratory tract specimens

On designing observers for time-delay systems with nonlinear disturbances

This is the post print version of the article. The official published version can be obtained from the link below - Copyright 2002 Taylor & Francis LtdIn this paper, the observer design problem is studied for a class of time-delay nonlinear systems. The system under consideration is subject to delayed state and non-linear disturbances. The time-delay is allowed to be time-varying, and the non-linearities are assumed to satisfy global Lipschitz conditions. The problem addressed is the design of state observers such that, for the admissible time-delay as well as non-linear disturbances, the dynamics of the observation error is globally exponentially stable. An effective algebraic matrix inequality approach is developed to solve the non-linear observer design problem. Specifically, some conditions for the existence of the desired observers are derived, and an explicit expression of desired observers is given in terms of some free parameters. A simulation example is included to illustrate the practical applicability of the proposed theory.The work of Z. Wang was supported in part by the University of Kaiserslautern of Germany and the Alexander von Humboldt Foundation of Germany

Intense physical activity is associated with cognitive performance in the elderly

Numerous studies have reported positive impacts of physical activity on cognitive function. However, the majority of these studies have utilised physical activity questionnaires or surveys, thus results may have been influenced by reporting biases. Through the objective measurement of routine levels of physical activity via actigraphy, we report a significant association between intensity, but not volume, of physical activity and cognitive functioning. A cohort of 217 participants (aged 60–89 years) wore an actigraphy unit for 7 consecutive days and underwent comprehensive neuropsychological assessment. The cohort was stratified into tertiles based on physical activity intensity. Compared with individuals in the lowest tertile of physical activity intensity, those in the highest tertile scored 9%, 9%, 6% and 21% higher on the digit span, digit symbol, Rey Complex Figure Test (RCFT) copy and Rey Figure Test 30-min recall test, respectively. Statistically, participants in the highest tertile of physical activity intensity performed significantly better on the following cognitive tasks: digit symbol, RCFT copy and verbal fluency test (all P<0.05). The results indicate that intensity rather than quantity of physical activity may be more important in the association between physical activity and cognitive function