14,846 research outputs found
Metastable Innershell Molecular State (MIMS)
We propose that the existence of Metastable Innershell Molecular State (MIMS)
was experimentally discovered by Bae et al. in hypervelocity (v>100km/s) impact
of nanoparticles. The decay of MIMS resulted in the observed intense soft
x-rays in the range of 75 - 100 eV in agreement with Winterberg's recent
prediction.Comment: Submitted to Physics Letters
Racial and Ethnic Differences in Cardiovascular Disease Risk Factors in U.S. Older Women: Findings from Behavioral Risk Factor Surveillance Survey, 2003 & 2004
The purpose of this study was to examine racial and ethnic variations in the modifiable CVD risk factors in older women (65 years and older). The study data was drawn from the merged 2003 and 2004 national Behavioral Risk Factor Surveillance Survey (BRFSS). Multinomial regression analyses for indicator outcome and multiple logistic regression analyses for binary outcomes were performed to determine the relationship between each of the six dependent variable and the independent variables. Compared to older white women, older black women had significantly higher odds of hypertension, diabetes and obesity. No significant association was found between Hispanics and hypertension. However Hispanics were found to be more likely to have diabetes and no leisure-time physical activity compared to whites. Hispanics were also found to have lower odds of smoking compared to whites. American Indian and Alaskan Native (AIAN) s were found to have significantly higher odds of diabetes and obesity compared to whites. No significant association between AIANs and smoking was found. Overall, there are striking racial and ethnic differences in the CVD risk factors among older U.S women after controlling for socio-economic status. It is evident from these findings that in designing interventions to reduce cardiovascular risks for elderly women, clearly “one size does not fit all.” These findings highlight the need for development and implementation of appropriate public health programs aimed at these various target communities
Josephson-vortex-flow terahertz emission in layered high- superconducting single crystals
We report on the successful terahertz emission (0.61 THz) that is
continuous and tunable in its frequency and power, by driving Josephson
vortices in resonance with the collective standing Josephson plasma modes
excited in stacked BiSrCaCuO intrinsic Josephson junctions.
Shapiro-step detection was employed to confirm the terahertz-wave emission. Our
results provide a strong feasibility of developing long-sought solid-state
terahertz-wave emission devices
Electrical phase change of CVD-grown Ge-Sb-Te thin film device
A prototype Ge-Sb-Te thin film phase-change memory device has been fabricated and reversible threshold and phase change switching demonstrated electrically, with a threshold voltage of 1.5 – 1.7 V. The Ge-Sb-Te thin film was fabricated by chemical vapour deposition (CVD) at atmospheric pressure using GeCl4, SbCl5, and Te precursors with reactive gas H2 at reaction temperature 780 °C and substrate temperature 250 °C. The surface morphology and composition of the CVD-grown Ge-Sb-Te thin film has been characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The CVD-grown Ge-Sb-Te thin film shows promise for the phase change memory applications
Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke
Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance—walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint powers, and metabolic power. Compared to walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4±6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic (R2= 0.83, P= 0.004) and nonparetic (R2= 0.73, P= 0.014) ankle power. Interestingly, despite the exosuit providing direct assistance to only the paretic limb, changes in metabolic power were related to changes in nonparetic limb COM power (R2= 0.80, P= 0.007), not paretic limb COM power (P> 0.05). These findings provide a fundamental understanding of how individuals poststroke interact with an exosuit to reduce the metabolic cost of hemiparetic walking.Accepted manuscript2019-03-0
Hamiltonian and measuring time for analog quantum search
We derive in this study a Hamiltonian to solve with certainty the analog
quantum search problem analogue to the Grover algorithm. The general form of
the initial state is considered. Since the evaluation of the measuring time for
finding the marked state by probability of unity is crucially important in the
problem, especially when the Bohr frequency is high, we then give the exact
formula as a function of all given parameters for the measuring time.Comment: 5 page
Exosuit-induced improvements in walking after stroke: comprehensive analysis on gait energetics and biomechanics
Outstanding Poster Presentation Finalis
A V-Diagram for the Design of Integrated Health Management for Unmanned Aerial Systems
Designing Integrated Vehicle Health Management (IVHM) for Unmanned Aerial Systems (UAS) is inherently complex. UAS are a system of systems (SoS) and IVHM is a product-service, thus the designer has to take into account many factors, such as: the design of the other systems of the UAS (e.g. engines, structure, communications), the split of functions between elements of the UAS, the intended operation/mission of the UAS, the cost verses benefit of monitoring a system/component/part, different techniques for monitoring the health of the UAS, optimizing the health of the fleet and not just the individual UAS, amongst others. The design of IVHM cannot sit alongside, or after, the design of UAS, but itself be integrated into the overall design to maximize IVHM’s potential.
Many different methods exist to help design complex products and manage the process. One method used is the V-diagram which is based on three concepts: decomposition & definition; integration & testing; and verification & validation. This paper adapts the V-diagram so that it can be used for designing IVHM for UAS. The adapted v-diagram splits into different tracks for the different system elements of the UAS and responses to health states (decomposition and definition). These tracks are then combined into an overall IVHM provision for the UAS (integration and testing), which can be verified and validated. The stages of the adapted V-diagram can easily be aligned with the stages of the V-diagram being used to design the UAS bringing the design of the IVHM in step with the overall design process. The adapted V-diagram also allows the design IVHM for a UAS to be broken down in to smaller tasks which can be assigned to people/teams with the relevant competencies. The adapted V-diagram could also be used to design IVHM for other SoS and other vehicles or products
Inferring meta-covariates in classification
This paper develops an alternative method for gene selection that combines model based clustering and binary classification. By averaging the covariates within the clusters obtained from model based clustering, we define “meta-covariates” and use them to build a probit regression model, thereby selecting clusters of similarly behaving genes, aiding interpretation. This simultaneous learning task is accomplished by an EM algorithm that optimises a single likelihood function which rewards good performance at both classification and clustering. We explore the performance of our methodology on a well known leukaemia dataset and use the Gene Ontology to interpret our results
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