Constructing a gazebo: supporting teamwork in a tightly coupled, distributed task in virtual reality

Many tasks require teamwork. Team members may work concurrently, but there must be some occasions of coming together. Collaborative virtual environments (CVEs) allow distributed teams to come together across distance to share a task. Studies of CVE systems have tended to focus on the sense of presence or copresence with other people. They have avoided studying close interaction between us-ers, such as the shared manipulation of objects, because CVEs suffer from inherent network delays and often have cumbersome user interfaces. Little is known about the ef-fectiveness of collaboration in tasks requiring various forms of object sharing and, in particular, the concurrent manipu-lation of objects. This paper investigates the effectiveness of supporting teamwork among a geographically distributed group in a task that requires the shared manipulation of objects. To complete the task, users must share objects through con-current manipulation of both the same and distinct at-tributes. The effectiveness of teamwork is measured in terms of time taken to achieve each step, as well as the impression of users. The effect of interface is examined by comparing various combinations of walk-in cubic immersive projection technology (IPT) displays and desktop devices

Shear lag in truss core sandwich beams

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 30).An experimental study was conducted to investigate the possible influence of shear lag in the discrepancy between the theoretical and measured stiffness of truss core sandwich beams. In previous studies, the measured values of stiffness in loading have proven to be 50% of the theoretical stiffness during three point bending tests. To test the effect of shear lag on this phenomenon, the beams' dimensions were altered to decrease the presence of shear lag in a gradual manner so a trend could be observed. The experimental trails were carried out on three types of beams each with different diameters of truss material. Results show that this study has improved the accuracy of the measured results from previous studies with the two smallest truss diameter beams. Because the discrepancy between the theoretical and measured values is the greatest for the largest beams, (when the shear deflection has the least influence), it is concluded that shear lag is not responsible for the discrepancy between measured and theoretical stiffness.by Ryan Roberts.S.B

Predicting Postprobationary Job Performance of Police Officers Using CPI and MMPI–2–RF Test Data Obtained During Preemployment Psychological Screening

We examined associations between prehire California Psychological Inventory (CPI) and prorated Minnesota Multiphasic Personality Inventory–2 Restructured Form (MMPI–2–RF) scores (calculated from MMPI profiles) and supervisor ratings for a sample of 143 male police officers. Substantive scale scores in this sample were meaningfully lower than those obtained by the tests’ normative samples in the case of the MMPI–2–RF and meaningfully higher in the case of the CPI (indicating less psychological dysfunction). Test scores from both instruments showed substantial range restriction, consistent with those produced by members of the police candidate comparison groups (Corey & Ben-Porath, 2014Corey, D. M., & Ben-Porath, Y. S. (2014). User\u27s guide for the MMPI-2-RF Police Candidate Interpretive Report. Minneapolis, MN: University of Minnesota Press. [Google Scholar]; Roberts & Johnson, 2001Roberts, M. D., & Johnson, M. (2001). CPI: Police and public safety selection report technical manual. Unpublished manuscript. Retrieved fromhttp://media.post.ca.gov/. [Google Scholar]). After applying a statistical correction for range restriction, we found a number of meaningful associations between both CPI and MMPI–2–RF substantive scale scores and supervisor ratings. For the MMPI–2–RF, findings for scales from the emotional dysfunction and interpersonal functioning domains of the test were particularly strong. For the CPI, findings for scales indicating conformity with social norms, integrity, and tolerance were strong, as were the findings for an index indicating risk of termination. Hierarchical regression analyses showed that MMPI–2–RF and CPI scores complement each other, accounting for incremental variance in the prediction of job-related variables over and above each other. Implications of these findings for assessment science and practice are discussed

Springs of Florida

bulletin which documented the major and important springs in the state (Ferguson et al., 1947). This publication was revised in 1977, with many previously undocumented springs and many new water-quality analyses being added (Rosenau et al., 1977). The Florida Geological Survey's report on first magnitude springs (Scott et al., 2002) was the initial step in once again updating and revising the Springs of Florida bulletin. The new bulletin includes the spring descriptions and water-quality analyses from Scott et al. (2002). Nearly 300 springs were described in 1977. As of 2004, more than 700 springs have been recognized in the state and more are reported each year. To date, 33 first magnitude springs (with a flow greater than 100 cubic feet per second or approximately 64.6 million gallons of water per day) have been recognized in Florida, more than any other state or country (Rosenau et al., 1977). Our springs are a unique and invaluable natural resource. A comprehensive understanding of the spring systems will provide the basis for their protection and wise use. (Document pdf contains 677 pages

Perceived Stress and Self-Care in Graduate Students Amidst the COVID-19 Pandemic

Introduction: This study examines the perceived stress and self-care behaviors of graduate students as impacted by the COVID-19 pandemic. Students who participated had varying degree concentrations, with the majority of participants having a Clinical Mental Health Counseling, Couples and Family Therapy, Dance Movement Therapy, or Clinical Psychology focus. This study is particularly relevant to health care workers, especially those whose focus is mental health. Markedly elevated prevalence of reported adverse mental and behavioral health conditions associated with the COVID-19 pandemic highlight the broad impact of the pandemic and the need to prevent and treat these conditions. This study sought to examine the presence and significance of a relationship between perceived stress, self-care strategies, and participant characteristics and the impact of COVID-19. Methods: Utilizing a quantitative approach, data were collected via survey method using related questionnaires and assessments; approximately 700 surveys were disseminated to the student-body, with a response rate of 24% yielding 170 initial participants. Pearson bivariate and multiple regression were used to determine the statistical significance of any potential relationship as posed by the research questions. Results: A statistically significant relationship was found between perceived stress and the impact of COVID-19 for the students. Also, using multiple regression, age (p = .005) and race/ethnic identity (p = .006) contributed to the reported levels of perceived stress. Racial identity was a significant predictor of the reported scores on the impact of COVID-19 (p = .01). There was also a significant relationship (p \u3c.001) between adequate sleep and eating nutritiously (p = .016) and reported perceived stress and the impact of COVID-19. Lastly, engaging in social activism was related to an increased impact of COVID-19 (p=.037), specifically for the subscale of hyperarousal (p=.016). Conclusion: A summary of our findings indicates a significant relationship between participant’s perceived stress and the impact of COVID-19; specifically, as the level of perceived stress increased for our participants, so did the impact of the COVID-19 pandemic. Seemingly, those who experience greater daily stress in their lives reported a more significant impact of COVID-19 on their daily lives. These results point to the need for wellness strategies specific to stress reduction strategies to also help in alleviating the distress associated with COVID-19. As universities transition to online learning, online accessible interventions aimed at helping students address stress, depression, and wellbeing, may prove beneficial

Divide-and-Conquer Monte Carlo Fusion

Combining several (sample approximations of) distributions, which we term sub-posteriors, into a single distribution proportional to their product, is a common challenge. For instance, in distributed `big data' problems, or when working under multi-party privacy constraints. Many existing approaches resort to approximating the individual sub-posteriors for practical necessity, then representing the resulting approximate posterior. The quality of the posterior approximation for these approaches is poor when the sub-posteriors fall out-with a narrow range of distributional form. Recently, a Fusion approach has been proposed which finds a direct and exact Monte Carlo approximation of the posterior (as opposed to the sub-posteriors), circumventing the drawbacks of approximate approaches. Unfortunately, existing Fusion approaches have a number of computational limitations, particularly when unifying a large number of sub-posteriors. In this paper, we generalise the theory underpinning existing Fusion approaches, and embed the resulting methodology within a recursive divide-and-conquer sequential Monte Carlo paradigm. This ultimately leads to a competitive Fusion approach, which is robust to increasing numbers of sub-posteriors.Comment: 24 pages, 8 figure

Mathematical model predicts anti-adhesion--antibiotic--debridement combination therapies can clear an antibiotic resistant infection

As antimicrobial resistance increases, it is crucial to develop new treatment strategies to counter the emerging threat. In this paper, we consider combination therapies involving conventional antibiotics and debridement, coupled with a novel anti-adhesion therapy, and their use in the treatment of antimicrobial resistant burn wound infections. Our models predict that anti-adhesion–antibiotic–debridement combination therapies can eliminate a bacterial infection in cases where each treatment in isolation would fail. Antibiotics are assumed to have a bactericidal mode of action, killing bacteria, while debridement involves physically cleaning a wound (e.g. with a cloth); removing free bacteria. Anti-adhesion therapy can take a number of forms. Here we consider adhesion inhibitors consisting of polystyrene microbeads chemically coupled to a protein known as multivalent adhesion molecule 7, an adhesin which mediates the initial stages of attachment of many bacterial species to host cells. Adhesion inhibitors competitively inhibit bacteria from binding to host cells, thus rendering them susceptible to removal through debridement. An ordinary differential equation model is developed and the antibiotic-related parameters are fitted against new in vitro data gathered for the present study. The model is used to predict treatment outcomes and to suggest optimal treatment strategies. Our model predicts that anti-adhesion and antibiotic therapies will combine synergistically, producing a combined effect which is often greater than the sum of their individual effects, and that anti-adhesion–antibiotic–debridement combination therapy will be more effective than any of the treatment strategies used in isolation. Further, the use of inhibitors significantly reduces the minimum dose of antibiotics required to eliminate an infection, reducing the chances that bacteria will develop increased resistance. Lastly, we use our model to suggest treatment regimens capable of eliminating bacterial infections within clinically relevant timescales