1,926 research outputs found

    Enhanced reverse saturable absorption and optical limiting in heavy-atom-substituted phthalocyanines

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    The reverse saturable absorption and the optical-limiting response of metal phthalocyanines can be enhanced by use of the heavy-atom effect. Phthalocyanines containing heavy-metal atoms, such as In, Sn, and Pb, show a nearly factor-of-2 enhancement in the ratio of effective excited-state to ground-state absorption cross sections compared with those containing lighter atoms, such as Al and Si. In an f/8 optical geometry, homogeneous solutions of heavy-metal phthalocyanines, at 30% linear transmission, limit 8-ns 532-nm laser pulses to ≤ 3 µJ the energy for 50% probability of eye damage) for incident energies as high as 800 µJ

    Comparison of Two Methods for Improving Distance Perception in Virtual Reality

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    Distance is commonly underperceived in virtual environments (VEs) compared to real environments. Past work suggests that displaying a replica VE based on the real surrounding environment leads to more accurate judgments of distance, but that work has lacked the necessary control conditions to firmly make this conclusion. Other research indicates that walking through a VE with visual feedback improves judgments of distance and size. This study evaluated and compared those two methods for improving perceived distance in VEs. All participants experienced a replica VE based on the real lab. In one condition, participants visually previewed the real lab prior to experiencing the replica VE, and in another condition they did not. Participants performed blind-walking judgments of distance and also judgments of size in the replica VE before and after walking interaction. Distance judgments were more accurate in the preview compared to no preview condition, but size judgments were unaffected by visual preview. Distance judgments and size judgments increased after walking interaction, and the improvement was larger for distance than for size judgments. After walking interaction, distance judgments did not differ based on visual preview, and walking interaction led to a larger improvement in judged distance than did visual preview. These data suggest that walking interaction may be more effective than visual preview as a method for improving perceived space in a VE

    Water: Place. Experience. In Literature, Visual & Performing Arts

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    Kelly Richardson, Emily Morgan and Laura Dougherty will engage in a ten-week collaborative project with theatre and dance students. Drawing from students in these two performance disciplines, we will, as a group, develop a site specific theatre/dance performance responding to and inspired by the idea of access, sustainability, presence and absence of Water in the World. We have been accepted to present at the National Dance Education Organization conference in October, where we plan to take a pause. Our idea is that we use that pause to reflect on our process up to that point. For this presentation, we hope to reflect on the project, as whole, as well as the site specific performance at the Water Conference. In this presentation will we chart the process of site selection, generating meaning through theatre and dance, devising performance, the successes, failures, and potential future iterations of the work. We are interested in the generative space created by this reflection, and hope for response from performers and audience members alike

    Effects of Swim Strokes in Labor-wear With and Without a Personal Flotation Device

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    We determined how three different swim strokes were affected by standard labor-wear with and without use of a personal flotation device (PFD). The two main research questions included (1) what effects would standard labor-wear have on the American crawl, elementary back stroke and breast stroke with and without a PFD for 11.4 m (12.5 yds).  The sub questions included: (2) Will the addition of the PFD improve swim times? We addressed these questions with six hypotheses. Statistical analysis showed statistically significant P-values for the American crawl (no PFD 23.29 sec, PFD 18.29 sec, P = 0.0010) and back stroke (no PFD 36.96 sec, PFD 31.00 sec, P = 0.0223); the strokes showed improved swim times with the PFD. We detected no statistical evidence (P = 0.2086) for the mean swim time (22.61 sec) for the breast stroke with PFD and the mean swim time (23.00 sec) for breast stroke without a PFD. Swim time between swimmers with and without a PFD differed. The mean swim time for all swimmers with a PFD (24.17sec) was faster than the mean swim time for all swimmers without a PFD (27.75 sec, P = 0.0153). The mean swim time for swimmers using the elementary back stroke (33.98 sec) was slower than the mean swim time for swimmers using the crawl stroke (21.10 sec, P < 0.0001) and the mean swim time for swimmers using the breast stroke (22.81 sec).  We detected no difference between the mean swim time for swimmers using the crawl stroke and the mean swim time for swimmers using the breast stroke. We also detected no evidence (P = 0.164) of a stroke X flotation interaction effect

    Awareness of Vision Zero among United States’ road safety professionals

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    Abstract Background Vision Zero is a strategy to eliminate all fatalities and serious injuries from road traffic crashes, while increasing safe and equitable mobility for all. In 2015, the United States’ Department of Transportation announced the official target of the federal government transportation safety policy was zero deaths. In 2017, we assessed the dissemination of Vision Zero in the United States. Methods We conducted a web-based survey in 2017 among road safety professionals. Email invitations were sent using relevant membership directories and conference lists. Results We surveyed 192 road safety professionals, including planning/engineering (57.8%), public health (16.7%), and law enforcement/emergency medical services (EMS) (8.9%). Awareness of Vision Zero was higher among planning/engineering fields (97.3%) compared to law enforcement/EMS (76.5%) and public health (75.0%). Awareness was similar by number of years working in the field. Awareness was higher in the South (95.9%) and Northeast (95.0%) regions, followed by the West (90.8%) and Midwest (85.2%) Census regions. Among those that heard of Vision Zero (n = 174), 41.8% worked at a municipality with a Vision Zero campaign, while 41.2% did not. Among those working at a municipality with a Vision Zero campaign (n = 71), about half participated in the campaign (54.9%) while the other half did not (45.1%). Conclusions With widespread dissemination of the Vision Zero strategy to road safety professionals, next steps include evaluating how Vision Zero is being adopted, implemented, and maintained in communities, as well as the awareness and acceptability by community members, and to identify the most promising policies and practices

    Angiotensin II-inhibition:effect on Alzheimer's pathology in the aged triple transgenic mouse

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    Reducing excessive accumulation of amyloid-β (Aβ) in Alzheimer's disease (AD) is a key objective of most AD therapies, and inhibition of angiotensin-converting enzyme (ACE) may delay onset or progression of AD. The effects of an ACE-inhibitor (ACE-I) and an angiotensin II receptor blocker (ARB) on Aβ and tau pathology in a triple transgenic (3xTGAD) mouse model of AD were investigated. 9-10month 3xTGAD mice were treated with ARB, ACE-I or vehicle for 6 months. Mean arterial blood pressure (MABP) was measured periodically and mice were assessed behaviourally. Aβ, phospho-tau, amyloid precursor protein (APP) and ACE activity were analysed. MABP was significantly reduced at 2 weeks and 3 months in the ACE-I group and at 3 months in the ARB group, compared to vehicle. Neither drug altered performance of 3xTGAD mice in Morris Water Maze or T-maze, nor were Aβ, tau immunolabelling or APP levels altered. ACE-I significantly reduced ACE activity in kidney. Prolonged treatment with ACE-I or ARB does not affect Aβ or phospho-tau accumulation in brains of aged 3xTGAD mice

    A Measure of Burnout in Current NCAA Student-Athletes

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    Introduction. The prevalence of athletes who specialize in sports has increased in recent years. Substantial literature on youth sports has linked early sport specialization to negative consequences, such as burnout and injury. However, empirical evidence comparing rates of burnout and specialization in NCAA athletes is limited. The purpose of this study was to survey current NCAA Division I student-athletes to compare levels of burnout to sex, year of NCAA eligibility, and age at the beginning of sport specialization. Methods. A self-reported survey was distributed to student-athletes at two NCAA Division I institutions, which included demographics, sport specialization history, injury history, and the Athlete Burnout Questionnaire. Results from the three measures of the Athlete Burnout Questionnaire (reduced sense of accomplishment, exhaustion, sport devaluation) were compared to sex, year of NCAA eligibility, age of beginning sport specialization, and injury history. Results. A total of 267 athletes (95 males and 172 females) completed the survey. Of those, 156 (58.4%) were in their first or second year of NCAA eligibility, and 111 (41.6%) were in their third, fourth, or fifth year. Of the total, 121 (46.4%) reported specializing before the age of 15, and 140 (53.6%) specialized at age 16 or older. Females reported significantly higher levels of exhaustion than males (Difference of means (M) = 0.43, 95% confidence interval (CI) = [0.20, 0.66], p < 0.01). Athletes in their third, fourth, or fifth year of eligibility reported significantly higher levels of sport devaluation (M = 0.27, 95% CI = [0.05, 0.48], p < 0.05) than athletes in their first or second year. Athletes who specialized before age 15 did not report significantly higher levels of burnout than athletes who specialized at age 16 or later. In total, 203 athletes (77.2%) reported experiencing any injury. Athletes who reported a history of experiencing any injury demonstrated significantly higher feelings of reduced sense of accomplishment than athletes with no injury history (Difference of means (M) = 0.24, 95% confidence interval (CI) = [0.03, 0.45], p < 0.05). Conclusions. Athletes were more likely to experience elevated levels of burnout if they reported female sex, older NCAA eligibility, or a past injury history. However, athletes were not more likely to experience increased burnout based on age of beginning specialization. The results demonstrated a need to address burnout in athletes following injury and to be aware that females and older athletes are more prone to burnout

    Induction of antibody-mediated neutralization in SIVmac239 by a naturally acquired V3 mutation

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    AbstractAchieving humoral immunity against human immunodeficiency virus (HIV) is a major obstacle in AIDS vaccine development. Despite eliciting robust humoral responses to HIV, exposed hosts rarely produce broadly neutralizing antibodies. The present study utilizes simian immunodeficiency virus (SIV) to identify viral epitopes that conferred antibody neutralization to clone SIV/17E-CL, an in vivo variant derived from neutralization resistant SIVmac239. Neutralization assays using rhesus macaque monoclonal antibodies were performed on viruses engineered to express single or multiple amino acid mutations. Results identified a single amino acid mutation, P334R, in the carboxy-terminal half of the V3 loop as a critical residue that induced neutralization while retaining normal glycoprotein expression on the surface of the virus. Furthermore, the R334 residue yielded neutralization sensitivity by antibodies recognizing diverse conformational and linear epitopes of gp120, suggesting that neutralization phenotype was a consequence of global structural changes of the envelope protein rather than a specific site epitope

    α-Adrenergic inhibition of proliferation in HepG2 cells stably transfected with the α1B-adrenergic receptor through a p42MAP kinase/p21Cip1/WAF1-dependent pathway

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    AbstractActivation of α1B adrenergic receptors (α1BAR) promotes DNA synthesis in primary cultures of hepatocytes, yet expression of α1BAR in hepatocytes rapidly declines during proliferative events. HepG2 human hepatoma cells, which do not express α1BAR, were stably transfected with a rat α1BAR cDNA (TFG2 cells), in order to study the effects of maintained α1BAR expression on hepatoma cell proliferation. TFG2 cells had a decreased rate of growth compared to mock transfected HepG2 cells as revealed by a decrease in [3H]thymidine incorporation into DNA. Stimulation of α1BAR with phenylephrine caused a further large reduction in TFG2 cell growth, whereas no effect on growth was observed in mock transfected cells. Reduced cell growth correlated with increased percentages of cells found in G0/G1 and G2/M phases of the cell cycle. In TFG2 cells, phenylephrine increased p42MAP kinase activity by 1.5- to 2.0-fold for up to 24 h and increased expression of the cyclin dependent kinase inhibitor protein p21Cip1/WAF1. Treatment of TFG2 cells with the specific MEK1 inhibitor PD98059, or infection with a −/− MEK1 recombinant adenovirus permitted phenylephrine to increase rather than decrease [3H]thymidine incorporation. In addition, inhibition of MAP kinase signaling by PD98059 or MEK1 −/− blunted the ability of phenylephrine to increase p21Cip1/WAF1 expression. In agreement with a role for increased p21Cip1/WAF1 expression in causing growth arrest, infection of TFG2 cells with a recombinant adenovirus to express antisense p21Cip1/WAF1 mRNA blocked the ability of phenylephrine to increase p21Cip1/WAF1 expression and to inhibit DNA synthesis. Antisense p21Cip1/WAF1 permitted phenylephrine to stimulate DNA synthesis in TFG2 cells, and abrogated growth arrest. These results suggest that transformed hepatocytes may turn off the expression of α1BARs in order to prevent the activation of a growth inhibitory pathway. Activation of this inhibitory pathway via α1BAR appears to be p42MAP kinase and p21Cip1/WAF1 dependent
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