Sensitivity analysis for large-scale problems

The development of efficient techniques for calculating sensitivity derivatives is studied. The objective is to present a computational procedure for calculating sensitivity derivatives as part of performing structural reanalysis for large-scale problems. The scope is limited to framed type structures. Both linear static analysis and free-vibration eigenvalue problems are considered

Adjustment processes in chronic aphasia after stroke: Exploring multiple perspectives in the context of a community-based intervention

Background: The impact of chronic aphasia following stroke on quality of life (QOL) is widely acknowledged, with improved QOL recognised as an important outcome in aphasia recovery and supported by emerging quantitative measures. One of the key constructs recognised as contributing to QOL in other chronic conditions is psychosocial adjustment, the mechanisms of which are little understood for the person with aphasia. Aims: This study addressed adjustment processes in aphasia by exploring multiple perspectives from people engaged in the Communication Hub for Aphasia in North Tyneside (CHANT), a two-year community intervention for long-term aphasia. The study aimed to explore the adjustment process over time in people with aphasia using thematic analysis of personal narratives derived from a combination of sources: semi-structured interviews with reflections on experiences, quantitative measures of change in QOL and self-assessments of change. Methods & Procedures: Three people with mild or moderate chronic aphasia and three people without aphasia involved in CHANT were recruited (a carer, a volunteer, and a local government employee) to participate in semi-structured interviews at two- to three-month intervals over a 12-month period. A total of 28 semi-structured interviews were transcribed and analysed thematically by a small team using NVivo8 software. Narrative data were interpreted within the broader context of QOL measures and self-assessments of living with aphasia (Mumby & Whitworth, 2012).Outcomes & Results: Changes over time that reflected evidence of psychosocial adjustment from the multiple perspectives of the participants covered five core themes: Intervention type, Effectiveness, Barriers, Facilitators, and QOL. A model is proposed to encapsulate the barriers and facilitators that impacted on the process of adjustment and contributed to QOL for individuals involved in the intervention. This model is consistent with the domains from other classifications based on the International Classification of Functioning, Disability and Health (ICF; World Health Organization, 2001), viewing adjustment as a progression towards “wholeness”. The processes involved in personal (and specifically, emotional) adjustment to aphasia are explored, including three stages in rationalisation—Looking back, Looking around, and Looking forward—and the process of transforming negative emotional reactions into positive outcomes. Conclusions: The processes of adjustment in chronic aphasia are complex and vary both over time and according to individual perspectives and circumstances. This preliminary longitudinal study identified commonalities in participants engaged in long-term intervention over 12 months, enabling models of adjustment to be proposed for further exploration and evaluation

Star Formation triggered by cloud-cloud collisions

We present the results of SPH simulations in which two clouds, each having mass $M_{_{\rm{o}}}\!=\!500\,{\rm M}_{_\odot}$ and radius $R_{_{\rm{o}}}\!=\!2\,{\rm pc}$, collide head-on at relative velocities of $\Delta v_{_{\rm{o}}} =2.4,\;2.8,\;3.2,\;3.6\;{\rm and}\;4.0\,{\rm km}\,{\rm s}^{-1}$. There is a clear trend with increasing $\Delta v_{_{\rm{o}}}$. At low $\Delta v_{_{\rm{o}}}$, star formation starts later, and the shock-compressed layer breaks up into an array of predominantly radial filaments; stars condense out of these filaments and fall, together with residual gas, towards the centre of the layer, to form a single large-$N$ cluster, which then evolves by competitive accretion, producing one or two very massive protostars and a diaspora of ejected (mainly low-mass) protostars; the pattern of filaments is reminiscent of the hub and spokes systems identified recently by observers. At high $\Delta v_{_{\rm{o}}}$, star formation occurs sooner and the shock-compressed layer breaks up into a network of filaments; the pattern of filaments here is more like a spider's web, with several small-$N$ clusters forming independently of one another, in cores at the intersections of filaments, and since each core only spawns a small number of protostars, there are fewer ejections of protostars. As the relative velocity is increased, the {\it mean} protostellar mass increases, but the {\it maximum} protostellar mass and the width of the mass function both decrease. We use a Minimal Spanning Tree to analyse the spatial distributions of protostars formed at different relative velocities.Comment: 10 pages, 11 figure

Evidence that widespread star formation may be underway in G0.253+016, "The Brick"

Image cubes of differential column density as a function of dust temperature are constructed for Galactic Centre molecular cloud G0.253+0.016 ("The Brick") using the recently described PPMAP procedure. The input data consist of continuum images from the Herschel Space Telescope in the wavelength range 70-500 $\mu$m, supplemented by previously published interferometric data at 1.3 mm wavelength. While the bulk of the dust in the molecular cloud is consistent with being heated externally by the local interstellar radiation field, our image cube shows the presence, near one edge of the cloud, of a filamentary structure whose temperature profile suggests internal heating. The structure appears as a cool ($\sim 14$ K) tadpole-like feature, $\sim 6$ pc in length, in which is embedded a thin spine of much hotter ($\sim$ 40-50 K) material. We interpret these findings in terms of a cool filament whose hot central region is undergoing gravitational collapse and fragmentation to form a line of protostars. If confirmed, this would represent the first evidence of widespread star formation having started within this cloud.Comment: 5 pages, 4 figures; accepted for publication in MNRAS Letter

Which nondrug alternatives can help with insomnia?

Cognitive behavioral therapy (CBT) interventions -- particularly stimulus control and sleep hygiene -- are well-validated, effective treatments for chronic insomnia that are equivalent or superior to pharmacological interventions (strength of recommendation: A, based on systematic reviews). The long-term efficacy of CBT interventions, and their successful implementation by primary care physician (as compared with behavioral science providers), is unclear

A radiation driven implosion model for the enhanced luminosity of protostars near HII regions

Context. Molecular clouds near the H II regions tend to harbor more luminous protostars. Aims. Our aim in this paper is to investigate whether or not radiation-driven implosion mechanism enhances luminosity of protostars near regions of high-ionizing fluxes. Methods. We performed numerical simulations to model collapse of cores exposed to UV radiation from O stars. We investigated dependence of mass loss rates on the initial density profiles of cores and variation of UV fluxes. We derived simple analytic estimates of accretion rates and final masses of protostars. Results. Radiation-driven implosion mechanism can increase accretion rates of protostars by 1-2 orders of magnitude. On the other hand, mass loss due to photo-evaporation is not large enough to have a significant impact on the luminosity. The increase of accretion rate makes luminosity 1-2 orders higher than those of protostars that form without external triggering. Conclusions. Radiation-driven implosion can help explain the observed higher luminosity of protostars in molecular clouds near H II regions.Comment: 9 pages, 6 figures, accepted for publication in Astronomy and Astrophysic

Temperature as a third dimension in column-density mapping of dusty astrophysical structures associated with star formation

We present point process mapping (PPMAP), a Bayesian procedure that uses images of dust continuum emission at multiple wavelengths to produce resolution-enhanced image cubes of differential column density as a function of dust temperature and position. PPMAP is based on the generic ‘point process formalism, whereby the system of interest (in this case, a dusty astrophysical structure such as a filament or pre-stellar core) is represented by a collection of points in a suitably defined state space. It can be applied to a variety of observational data, such as Herschel images, provided only that the image intensity is delivered by optically thin dust in thermal equilibrium. PPMAP takes full account of the instrumental point-spread functions and does not require all images to be degraded to the same resolution. We present the results of testing using simulated data for a pre-stellar core and a fractal turbulent cloud, and demonstrate its performance with real data from the Herschel infrared Galactic Plane Survey (Hi-GAL). Specifically, we analyse observations of a large filamentary structure in the CMa OB1 giant molecular cloud. Histograms of differential column density indicate that the warm material (T ≳ 13 K) is distributed lognormally, consistent with turbulence, but the column densities of the cooler material are distributed as a high-density tail, consistent with the effects of self-gravity. The results illustrate the potential of PPMAP to aid in distinguishing between different physical components along the line of sight in star-forming clouds, and aid the interpretation of the associated Probability distribution functions (PDFs) of column density

SANDBOX CONTRACTING: AN EVALUATION OF GAMIFIED VS. TRADITIONAL CONTRACTING TRAINING METHODS AT THE USAF ENLISTED CONTRACTING TECHNICAL SCHOOL

This thesis involved an evaluation of gamified versus current (traditional) training methods employed by the instructors and faculty at the Air Force’s 344th Training Squadron (344 TRS) at Lackland Air Force Base, Texas, and by the professors at the Naval Postgraduate School (NPS) in Monterey, California. For our project, we designed and developed a first-person shooter (FPS) video game, titled Sandbox Contracting, that teaches the player basic contracting skills. Over the course of six weeks, we utilized this FPS video game to conduct an experiment in which a control group received the current (traditional) training methods employed by 344 TRS and NPS and a treatment group received the gamified version of the training. We assessed each student’s learning as well as their reaction to the assigned learning modality (traditional versus gaming) using post-training evaluation surveys. Traditional training methods outperformed gamified methods in most cases, but not all. We found that game design and mechanics impacted the student’s reactions and ultimately, the success of using gamified methods for learning. Additionally, the results demonstrated a genuine interest in using games for learning among the Air Force contracting students, given the right game design and mechanics. Lastly, we offer suggestions for areas in which further research should be conducted in the gamified versus traditional training arena.Outstanding ThesisCaptain, United States Air ForceCaptain, United States Air ForceCaptain, United States Air ForceApproved for public release. Distribution is unlimited

Social, Environmental, and Racial/Ethnic Factors in Diabetes Prevalence in the U.S.

PURPOSE: The purpose of this study was to determine the extent to which socioeconomic status, race/ ethnicity, and disparities in neighborhood environmental factors affect diabetes prevalence among U.S. adults. METHODS: County-level data were collected from the 1000 U.S. counties with the highest diabetes incidence and the 1000 U.S. counties with the lowest diabetes incidence using the 2014 USDA Food Environmental Atlas. The dependent measure was diabetes prevalence. Independent measures were median household income, percentage of people with no car, percentage of population that was black, white, or Hispanic, and the number of fitness centers, fast food restaurants, farmer’s markets, and grocery stores. Stepwise multiple linear regression was used to assess the relationship of these independent variables to diabetes incidence. RESULTS: Of the nine independent measures evaluated, seven explained a significant amount of the variance in diabetes prevalence (Table 1). Median household income accounted for the largest proportion of variance (38%) with the non-white population percentages collectively accounting for an additional 19%. The specific indicators of commercial entities accounted for small (≤1%) but significant proportions of variance. CONCLUSION: The results of this study indicate socioeconomic and racial/ethnic factors account for the majority of variance in prevalence of diabetes in the U.S. However, not only availability but access to healthy foods and lifestyle choices also seem to play a role in the magnitude of the incidence of diabetes. There is an apparent need for local and federal programs to focus on these high-risk areas of concentrated poverty and minority populations in order to educate communities, increase social support, and improve access to factors related to developing healthy lifestyles