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

Contentious Repertoires: Examining Lennon Walls in Hong Kong’s Social Unrest of 2019

Scholars have examined the mobilising roles of text and images played during social movements. Studies of the Lennon Walls in Hong Kong have also discussed how citizens expressed opinions, shared information, and mobilised support for political reform. Few studies, however, have systematically examined the content of post-it notes and images on Lennon Walls and explored how the persuasive functions of movements have been distributed across text and image. In the research reported in this article, 10,000 post-it notes and 2,076 images collected from Lennon Walls across 18 districts in Hong Kong between June 2019 and April 2020 were coded, revealing important differences not only in the discourses presented but also in the persuasive functions of text and image. This analysis provides a more robust analysis of how the Lennon Walls were shaped by Hong Kong contentious repertoires. Meanwhile, Lennon Walls also served as a site of contention bound by its own specific contentious repertoire which demonstrates the spatial practice of counter-framing. This article examines the segmentation and distribution of the movement’s persuasive functions across textual and visual means of communication, in which the legitimacy, acceptance, and diffusion of actions and claims were extensively utilised during the 2019 social unrest

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