Statistical Physics Modeling of Disordered Metallic Alloys

The great majority of metallic alloys in use are disordered. The material property of a disordered alloy changes on exposure to thermal, chemical, or mechanical forcing; the changes are often irreversible. We present a new first principle method for modeling disordered metallic alloys suitable for predicting how the morphology, strength, and transport property would evolve under arbitrary forcing conditions. Such a predictive capability is critically important in designing new alloys for applications, such as in new-generation fission and fusion reactors, where unrelenting harsh thermal loading conditions exist. The protocol is developed for constructing a coarse-grained model that can be specialized for the evolution of thermophysical properties of an arbitrary disordered alloy under thermal, stress, nuclear, or chemical forcing scenarios. We model a disordered binary alloy as a randomly close-packed (RCP) assembly of constituent atoms at given composition. As such, a disordered alloy specimen is an admixture of nanocrystallites and glassy matter. For the present purpose, we first assert that interatomic interactions are by repulsion only, but the contributions from the attractive part of the interaction are restored by treating the nanocrystallites as nanoscale pieces of a single crystalline solid composed of the same constituent atoms. Implementation of the protocol is discussed for heating of disordered metals, and results are compared to the known melting point data

Reducing Incidence of Sexual Harassment and Sexual Assault in the National Oceanic and Atmospheric Administration Fleet

The National Oceanic and Atmospheric Administration (NOAA) operates a fleet of 16 research and survey ships crewed by a mix of commissioned officers and civilian wage mariners. The shipboard environment presents unique challenges to prevention of sexual harassment and assault. This capstone proposes a policy to reduce incidence of sexual harassment and assault on NOAA ships by partnering with the U.S. Coast Guard to facilitate investigation of allegations and enact punitive measures against guilty parties

No immediate effects of highly cushioned shoes on basic running biomechanics

The aim of the study was to investigate the effects of highly cushioned shoes on running biomechanics. Sixteen recreational runners (8 males, 8 females) participated and ran at a self-selected pace across the force platform in the research laboratory wearing either the standard or highly cushioned shoes, in randomized order. Impact peak (IP), loading rate to IP (LR), active peak (AP), contact time (CT), strike index (SI), running velocity, and knee and ankle kinematics at initial contact (IC) and AP were recorded during the running trials. Overall, there was no effect of footwear on IP, LR, AP, CT and velocity (p>.05) with small effect sizes (ES.05). Our results indicate that the highly cushioned shoes did not show immediate changes in running biomechanics

The Devon Island Expedition

In 1959 the Arctic Institute of North America undertook an integrated program of long term research on Devon Island in the Queen Elizabeth Islands of arctic Canada. The co-ordinated studies were designed to help understand the interrelationships between the glacier ice of Devon Island, the ocean in Jones Sound, and the encompassing atmosphere. They are being carried out over a 3-year period under the leadership of Spencer Apollonio. The main effort is concentrated on attempts to evaluate such factors as physical, chemical, and biological variations in the arctic waters of Jones Sound caused by discharging glaciers; evaporation and transfer of moisture between the ocean waters and the ice-cap and glaciers; and the overall influences of solar radiation energy on the mass balance of the ice-cap, the biological production in the sea, and the growth and decay of sea-ice. Some supplementary studies in archaeology and geology are included in the expedition's work because of the marked deficiency of knowledge in those subjects for Devon Island. In the late summer of 1960 a main base was established on the north shore of Devon Island near Cape Skogn by an advance party of eight men taken in with their materials by the Canada Department of Transport icebreaker "d'Iberville". During a 3-week period buildings were erected and routes inland and to the ice-cap explored and marked, while an archaeological reconnaissance of the Cape Sparbo area was made by a small party under Mr. Gordon Lowther of McGill University. Everything was installed for a beginning of the 3-year program in April 1961. During the months of April to September 1961 21 men worked on extensive programs in geophysics, glaciology, marine biology and oceanography, meteorology, and surveying. Intensive work was also completed in archaeology and geology. ..

High-speed metamagnetic resistive switching of FeRh through Joule heating

Due to its proximity to room temperature and demonstrated high degree of temperature tunability, the metamagnetic ordering transition in FeRh is attractive for novel high-performance computing devices seeking to use magnetism as the state variable. We demonstrate electrical control of the transition via Joule heating in FeRh wires. Finite element simulations based on abrupt state transition within each domain result in a globally smooth transition that agrees with the experimental findings and provides insight into the thermodynamics involved. We measure a 150 K decrease in transition temperature with currents up to 60 mA, limited only by the dimensions of the device. The sizeable shift in transition temperature scales with current density and wire length, suggesting the absolute resistance and heat dissipation of the substrate are also important. The FeRh phase change is evaluated by pulsed I-V using a variety of bias conditions. We demonstrate high speed (~ ns) memristor-like behavior and report device performance parameters such as switching speed and power consumption that compare favorably with state-of-the-art phase change memristive technologies.Comment: 35 pages, 9 figure

Prediction of exercise capacity and training prescription from the 6-minute walk test and rating of perceived exertion

Walking tests, such as the 6-min walk test (6MWT), are popular methods of estimating peak oxygen uptake (VO(2)peak) in clinical populations. However, the strength of the distance vs. VO(2)peak relationship is not strong, and there are no equations for estimating ventilatory threshold (VT), which is important for training prescription and prognosis. Since the 6MWT is often limited by walking mechanics, prediction equations that include simple additional predictors, such as the terminal rating of perceived exertion (RPE), hold the potential for improving the prediction of VO(2)max and VT. Therefore, this study was designed to develop equations for predicting VO(2)peak and VT from performance during the 6MWT, on the basis of walking performance and terminal RPE. Clinically stable patients in a cardiac rehabilitation program (N = 63) performed the 6MWT according to the American Thoracic Society guidelines. At the end of each walk, the subject provided their terminal RPE on a 6–20 Borg scale. Each patient also performed a maximal incremental treadmill test with respiratory gas exchange to measure VO(2)peak and VT. There was a good correlation between VO(2)peak and 6MWT distance (r = 0.80) which was improved by adding the terminal RPE in a multiple regression formula (6MWT + RPE, R(2) = 0.71, standard error of estimate, SEE = 1.3 Metabolic Equivalents (METs). The VT was also well correlated with walking performance, 6MWT distance (r = 0.80), and was improved by the addition of terminal RPE (6MWT + RPE, R(2) = 0.69, SEE = 0.95 METs). The addition of terminal RPE to 6MWT distance improved the prediction of maximal METs and METs at VT, which may have practical applications for exercise prescription

Constraints on the Clustering, Biasing and Redshift Distribution of Radio Sources

We discuss how different theoretical predictions for the variance $\sigma^2$ of the distribution of radio sources can be matched to measurements from the FIRST survey at different flux limits. The predictions are given by the integration of models for the angular correlation function $w(\theta)$ for three different functional forms of the redshift distribution $N(z)$, different spatial correlation functions and by different evolutions of the bias $b(z)$ with redshift. We also consider the two cases of open and flat Universes. Although the predicted $w(\theta)$ show substantial differences due to differences in the $N(z)$'s, these differences are not significant compared to the uncertainties in the current observations. It turns out that the best fit is provided by models with constant biasing at all times, although the difference between models with epoch-independent bias and models with bias that evolves linearly with redshift is not very large. All models with strong evolution of bias with epoch are ruled out. As a further step we directly calculated $w_{obs}(\theta)$ at 3mJy from the catalogue and matched it with our models for the angular correlation function in the hypothesis that the clustering signal comes from two different populations, namely AGN-powered sources and starbursting galaxies. The results are consistent with a scenario for hierarchical clustering where the fainter starbursting galaxies trace the mass at all epochs, while brighter AGN's are strongly biased, with $b(z)$ evolving linearly with redshift, as suggested by some theories of galaxy formation and evolution.Comment: 14 pages, 12 figures, version to appear on MNRA

Factors associated with initial treatment and survival for clinically localized prostate cancer: results from the CDC-NPCR Patterns of Care Study (PoC1)

<p>Abstract</p> <p>Background</p> <p>Despite the large number of men diagnosed with localized prostate cancer, there is as yet no consensus concerning appropriate treatment. The purpose of this study was to describe the initial treatment patterns for localized prostate cancer in a population-based sample and to determine the clinical and patient characteristics associated with initial treatment and overall survival.</p> <p>Methods</p> <p>The analysis included 3,300 patients from seven states, diagnosed with clinically localized prostate cancer in 1997. We examined the association of sociodemographic and clinical characteristics with four treatment options: radical prostatectomy, radiation therapy, hormone therapy, and watchful waiting. Diagnostic and treatment information was abstracted from medical records. Socioeconomic measures were derived from the 2000 Census based on the patient's residence at time of diagnosis. Vital status through December 31, 2002, was obtained from medical records and linkages to state vital statistics files and the National Death Index. Multiple logistic regression analysis and Cox proportional hazards models identified factors associated with initial treatment and overall survival, respectively.</p> <p>Results</p> <p>Patients with clinically localized prostate cancer received the following treatments: radical prostatectomy (39.7%), radiation therapy (31.4%), hormone therapy (10.3%), or watchful waiting (18.6%). After multivariable adjustment, the following variables were associated with conservative treatment (hormone therapy or watchful waiting): older age, black race, being unmarried, having public insurance, having non-screen detected cancer, having normal digital rectal exam results, PSA values above 20, low Gleason score (2-4), comorbidity, and state of residence. Among patients receiving definitive treatment (radical prostatectomy or radiation therapy), older age, being unmarried, PSA values above 10, unknown Gleason score, state of residence, as well as black race in patients under 60 years of age, were associated with receipt of radiation therapy. Overall survival was related to younger age, being married, Gleason score under 8, radical prostatectomy, and state of residence. Comorbidity was only associated with risk of death within the first three years of diagnosis.</p> <p>Conclusions</p> <p>In the absence of clear-cut evidence favoring one treatment modality over another, it is important to understand the factors that inform treatment selection. Since state of residence was a significant predictor of both treatment as well as overall survival, true regional differences probably exist in how physicians and patients select treatment options. Factors affecting treatment choice and treatment effectiveness need to be further explored in future population-based studies.</p