202 research outputs found

    Psychometric properties of the World Health Organization WHOQOL-BREF quality of life assessment in Singapore

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    Purpose: This study validated the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire with 3,400 respondents living in Singapore. Methods: The ethnic composition was 76.1% Chinese, 12.3% Malay, 9.6% Indian, and 2% Others. The sample included adults with disabilities (28.9%), adults recovering from mental health issues (14%), and adults from the general population (57.1%). Questionnaires about health-related conditions, the effects of disability on everyday functioning (WHODAS 2.0), the WHOQOL-BREF, and add-on modules of QOL of people with disabilities (WHOQOL-DIS) and QOL of elders (WHOQOL-OLD) were administrated. Results: Confirmatory factor analysis supported a construct of QOL made of four domains, revealing good construct validity. The four domains predicted overall QOL and health satisfaction. Good internal consistency was evidenced by high alpha coefficients for the physical (.79), psychological (.82), social relationships (.81), and environment (.83) domains. Convergent validity was shown by moderate correlations between the different questionnaires measuring QOL (WHOQOL-BREF, WHOQOL-DIS, and WHOQOL-OLD), and discriminant validity by a lower correlation between the WHOQOL-BREF and disability. Convergent and divergent validity were also indicated by higher correlations between similar constructs across the different measures, and lower correlations between dissimilar constructs across measures, respectively. Concurrent validity was supported by showing that individuals with chronic medical conditions had lower QOL than individuals without chronic medical conditions. Conclusions: The results showed that the WHOQOL-BREF has sound psychometric properties and can be used to measure QOL in Singapore

    Strategies of the invasive tropical fire ant (Solenopsis geminata) to minimize inbreeding costs

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    How invasive species overcome challenges associated with low genetic diversity is unclear. Invasive ant populations with low genetic diversity sometimes produce sterile diploid males, which do not contribute to colony labour or reproductive output. We investigated how inbreeding affects colony founding and potential strategies to overcome its effects in the invasive tropical fire ant, Solenopsis geminata. Our genetic analyses of field samples revealed that 13–100% of males per colony (n = 8 males per 10 colonies) were diploid, and that all newly mated queens (n = 40) were single-mated. Our laboratory experiment in which we assigned newly mated queens to nests consisting of 1, 2, 3, or 5 queens (n = 95 ± 9 replicates) revealed that pleometrosis (queens founding their nest together) and diploid male larvae execution can compensate for diploid male load. The proportion of diploid male producing (DMP) colonies was 22.4%, and DMP colonies produced fewer pupae and adult workers than non-DMP colonies. Pleometrosis significantly increased colony size. Queens executed their diploid male larvae in 43.5% of the DMP colonies, and we hypothesize that cannibalism benefits incipient colonies because queens can redirect nutrients to worker brood. Pleometrosis and cannibalism of diploid male larvae represent strategies through which invasive ants can successfully establish despite high inbreeding

    Origin, behaviour, and genetics of reproductive workers in an invasive ant

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    Background Worker reproduction has an important influence on the social cohesion and efficiency of social insect colonies, but its role in the success of invasive ants has been neglected. We used observations of 233 captive colonies, laboratory experiments, and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost on interspecific defence. We determined the prevalence of worker production of males and whether it is triggered by queen absence; whether physogastric workers with enlarged abdomens are more likely to be reproductive, how normal workers and physogastric workers compare in their contributions to foraging and defence; and whether worker-produced males and males that could have been queen- or worker-produced differ in their size and heterozygosity. Results Sixty-six of our 233 captive colonies produced males, and in 25 of these, some males could only have been produced by workers. Colonies with more workers were more likely to produce males, especially for queenless colonies. The average number of days between the first appearance of eggs and adult males in our colonies was 54.1 ± 10.2 (mean ± SD, n = 20). In our laboratory experiment, queen removal triggered an increase in the proportion of physogastric workers. Physogastric workers were more likely to have yolky oocytes (37–54.9%) than normal workers (2–25.6%), which is an indicator of fertile or trophic egg production. Physogastric workers were less aggressive during interspecific aggression tests and foraged less than normal workers. The head width and wing length of worker-produced males were on average 4.0 and 4.3% greater respectively than those of males of undetermined source. Our microsatellite DNA analyses indicate that 5.5% of worker-produced males and 14.3% of males of undetermined source were heterozygous, which suggests the presence of diploid males and/or genetic mosaics in A. gracilipes. Conclusions Our experimental work provides crucial information on worker reproduction in A. gracilipes and its potential cost to colony defence. The ability of A. gracilipes workers to produce males in the absence of queens may also contribute to its success as an invasive species if intranidal mating can take place between virgin queens and worker-produced males

    Binar Space Program: Mission Two Payloads and Operations Plan

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    The second mission of Western Australia’s Binar Space Program consists of three 1U CubeSats targeting a 2023 launch. Aiming to improve the platform for future missions, the primary purpose of Binar 2, 3 and 4 is on-orbit testing of radiation shielding alloys developed by CSIRO. In this first-of-its-kind experiment, all three simultaneously deployed Binar spacecraft will contain radiation sensing payloads to assess the efficacy of various compositions of Australian made radiation shielding alloys. Alongside this, hardware changes to the Binar platform are discussed, including deployable solar arrays, additional communications solutions, and a removable payload bay. The Iridium network will be leveraged to test its suitability for CubeSat targeted re-entry. Several software-based payloads are implemented, including on-board hardware emulation, enabling an industry partner to control the spacecraft in a demonstration of remote operations capability. An undergraduate student lead project will continue on from Binar-1 to see a star tracker flown for testing alternative methods of attitude determination. From a community perspective, strengthening the engagement between amateur radio operators and the Binar Space Program will be explored by expanding on what amateurs can do with on-orbit satellites. Lastly, autonomous agile mission planning will be tested through an on-board multipurpose simulation running on the dual-core flight computer

    Crowd modeling and simulation technologies

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    As a collective and highly dynamic social group, the human crowd is a fascinating phenomenon that has been frequently studied by experts from various areas. Recently, computer-based modeling and simulation technologies have emerged to support investigation of the dynamics of crowds, such as a crowd's behaviors under normal and emergent situations. This article assesses the major existing technologies for crowd modeling and simulation. We first propose a two-dimensional categorization mechanism to classify existing work depending on the size of crowds and the time-scale of the crowd phenomena of interest. Four evaluation criteria have also been introduced to evaluate existing crowd simulation systems from the point of view of both a modeler and an end-user. We have discussed some influential existing work in crowd modeling and simulation regarding their major features, performance as well as the technologies used in this work. We have also discussed some open problems in the area. This article will provide the researchers with useful information and insights on the state of the art of the technologies in crowd modeling and simulation as well as future research directions.</jats:p

    LOGISTICS IN CONTESTED ENVIRONMENTS

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    This report examines the transport and delivery of logistics in contested environments within the context of great-power competition (GPC). Across the Department of Defense (DOD), it is believed that GPC will strain our current supply lines beyond their capacity to maintain required warfighting capability. Current DOD efforts are underway to determine an appropriate range of platforms, platform quantities, and delivery tactics to meet the projected logistics demand in future conflicts. This report explores the effectiveness of various platforms and delivery methods through analysis in developed survivability, circulation, and network optimization models. Among other factors, platforms are discriminated by their radar cross-section (RCS), noise level, speed, cargo capacity, and self-defense capability. To maximize supply delivered and minimize the cost of losses, the results of this analysis indicate preference for utilization of well-defended convoys on supply routes where bulk supply is appropriate and smaller, and widely dispersed assets on shorter, more contested routes with less demand. Sensitivity analysis on these results indicates system survivability can be improved by applying RCS and noise-reduction measures to logistics assets.Director, Warfare Integration (OPNAV N9I)Major, Israel Defence ForcesCivilian, Singapore Technologies Engineering Ltd, SingaporeCommander, Republic of Singapore NavyCommander, United States NavyCaptain, Singapore ArmyLieutenant, United States NavyLieutenant, United States NavyMajor, Republic of Singapore Air ForceCaptain, United States Marine CorpsLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyCaptain, Singapore ArmyLieutenant Junior Grade, United States NavyCaptain, Singapore ArmyLieutenant Colonel, Republic of Singapore Air ForceApproved for public release. distribution is unlimite

    Discovery of charge order and corresponding edge state in kagome magnet FeGe

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    Kagome materials often host exotic quantum phases, including spin liquids, Chern gap, charge order, and superconductivity. Existing scanning microscopy studies of the kagome charge order have been limited to non-kagome surface layers. Here we tunnel into the kagome lattice of FeGe to uncover features of the charge order. Our spectroscopic imaging identifes a 2x2 charge order in the magnetic kagome lattice, resembling that discovered in kagome superconductors. Spin-mapping across steps of unit-cell-height demonstrates that this charge order emerges from spin-polarized electrons with an antiferromagnetic stacking order. We further uncover the correlation between antiferromagnetism and charge order anisotropy, highlighting the unusual magnetic coupling of the charge order. Finally, we detect a pronounced edge state within the charge order energy gap, which is robust against the irregular shape of the kagome lattice edges. We discuss our results with the theoretically considered topological features of the kagome charge order including orbital magnetism and bulk-boundary correspondence
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