5,544 research outputs found

    Overcoming the boundary layer turbulence at Dome C: ground-layer adaptive optics versus tower

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    The unique atmospheric conditions present at sites such as Dome C on the Antarctic plateau are very favorable for high spatial resolution astronomy. At Dome C, the majority of the optical turbulence is confined to a 30 to 40 m thick stable boundary layer that results from the strong temperature inversion created by the heat exchange between the air and the ice-covered ground. To fully realize the potential of the exceptionally calm free atmosphere, this boundary layer must be overcome. In this article we compare the performance of two methods proposed to beat the boundary layer: mounting a telescope on a tower that physically puts it above the turbulent layer, and installing a telescope at ground level with a ground-layer adaptive optics system. A case is also made to combine these two methods to further improve the image quality

    A multicountry perspective on gender differences in time use during COVID-19

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    The COVID-19 pandemic has fundamentally altered how people spend time, with possible consequences for subjective well-being. Using diverse samples from the United States, Canada, Denmark, Brazil, and Spain (n = 31,141), following a preregistered analytic plan, and employing both mega- and meta-analyses, we find consistent gender differences in time spent on necessities. During the pandemic, women—especially mothers—spent more time on tasks such as childcare and household chores. To the extent that women spent more time on chores than men, they reported lower happiness. These data represent one of the most rigorous investigations of gender differences in time use during the forced lockdowns created by the COVID-19 pandemic, and point toward individual differences that should be considered when designing policies now and post–COVID-19

    Real-Time Maps of Fluid Flow Fields in Porous Biomaterials

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    Mechanical forces such as fluid shear have been shown to enhance cell growth and differentiation, but knowledge of their mechanistic effect on cells is limited because the local flow patterns and associated metrics are not precisely known. Here we present real-time, noninvasive measures of local hydrodynamics in 3D biomaterials based on nuclear magnetic resonance. Microflow maps were further used to derive pressure, shear and fluid permeability fields. Finally, remodeling of collagen gels in response to precise fluid flow parameters was correlated with structural changes. It is anticipated that accurate flow maps within 3D matrices will be a critical step towards understanding cell behavior in response to controlled flow dynamics.Comment: 23 pages, 4 figure

    Toward Enacted Cosmopolitan Citizenship: New Conceptualizations of African Immigrants’ Civic Learning and Action in the United States

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    The rapid growth of African residents in the U.S. is shaping global civil society, and calls for rethinking global identities and notions of global citizenship. This paper presents findings from a qualitative, interpretive case study on the civic learning and action of second- and 1.5-generation African immigrants in New York, U.S.A. We consider how African immigrants are constructing an understanding of their civic learning and action, and conceptualize an enacted cosmopolitan citizenship to better understand their civic engagement involving social justice issues in the U.S. and globally. We examine African immigrants' enacted cosmopolitan citizenship across two intersecting themes: 1) identities/attachments within and across local and global communities, and 2) enactments within and across local and global communities. We build upon theories of cosmopolitanism to extend understandings of an action-oriented global worldview of cosmopolitan citizenship, and point to implications for enacting new conceptualizations of citizenship and civic participation in global societies

    Where is the best site on Earth? Domes A, B, C and F, and Ridges A and B

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    The Antarctic plateau contains the best sites on earth for many forms of astronomy, but none of the existing bases was selected with astronomy as the primary motivation. In this article, we try to systematically compare the merits of potential observatory sites.We include South Pole, Domes A, C, and F, and also Ridge B (running northeast from Dome A), and what we call "Ridge A" (running southwest from Dome A). Our analysis combines satellite data, published results, and atmospheric models, to compare the boundary layer, weather, aurorae, airglow, precipitable water vapor, thermal sky emission, surface temperature, and the free atmosphere, at each site. We find that all Antarctic sites are likely to be compromised for optical work by airglow and aurorae. Of the sites with existing bases, Dome A is easily the best overall; but we find that Ridge A offers an even better site. We also find that Dome F is a remarkably good site. Dome C is less good as a thermal infrared or terahertz site, but would be able to take advantage of a predicted "OH hole" over Antarctica during spring.Comment: Revised version. 16 pages, 21 figures (22 in first version). Submitted to PASP 16/05/09, accepted 13/07/09; published 20/08/0

    A Conceptual Paradigm For Internet And Search Engine Marketing

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    The Internet continues to affect the relationships between business and their customers, and companies must adjust their online marketing strategy, if they want to increase revenues and market share, respectively. The emergence of the Internet over the last decade has had a major impact on the communication industry. The Internet is constantly evolving and is continually undergoing a rapid evolutionary process in both capabilities and uses. Marketing managers have begun to direct their focus and resources towards the Internet in an attempt to capture and garner new consumers. The Internet has forever changed the customer purchasing experience, and companies must alter their online marketing strategy, if they want to increase revenues and market share, respectively

    Dedication to David Dean

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    This special volume is dedicated to David H. Dean who passed away on August 11th, 2013. This dedication describes David's impact on the academic research on disability and, most notably, the vital interaction between research and policy. It discusses his influence in shaping perspectives on evaluating the effectiveness of programs to increase employment. Finally, it describes David as a person and why he was influential as a researcher and college professor

    Neighborhood Safety and Attractiveness Influence Physical Activity among African American and Hispanic or Latina Women

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    Introduction: Although the benefits of adopting physical activity (PA) are well publicized, physical inactivity rates remain high, and African American and Hispanic or Latina women do less PA compared to white women. Many interventions have begun to focus on conveniently performed lifestyle PA, such as walking. The purpose of this study was to investigate the relationship between neighborhood safety and attractiveness and PA in a sample of African American (AA) and Hispanic or Latina (HL) women participating in Health Is Power (1R01CA109403). Method: Women (AA N=202 and HL N=107) who enrolled in the study were middle-aged (M=45.8 years), overweight (M BMI=34.2 kg/m2) and largely sedentary (M accelerometer measured PA=19.6 min/day). Self-reported PA was measured by the International Physical Activity Questionnaire (IPAQ) long form and objectively measured PA was collected using an accelerometer at baseline (T1) and post intervention (T2). Neighborhood safety and attractiveness were measured by trained observers using the Pedestrian Environment Data Scan (PEDS). Results: At T1, African American women did more moderate intensity PA (M=24.3 vs. 10.9 minutes of moderate PA per day) and reported doing more walking (M=867.7 vs. 432.2 MET-minutes per day) than Hispanic or Latina women. At T2, African American still did more PA than Hispanic or Latina women (M=25.0 vs. 11.7 minutes of moderate PA per day), but there were no differences in self-reported PA. Bivariate associations showed that as safety (r=-0.144) and attractiveness (r=-0.149) for bicycling increased, self-reported walking decreased (ps\u3c0.05). Linear regression analyses indicated attractiveness for bicycling predicted increased T2 accelerometer measured PA (p=0.025), after adjusting for ethnicity, site, socioeconomic status (SES) and age. Conclusions: Neighborhood safety and attractiveness may influence PA. Community leaders and policy makers should consider the relationship between the built environment, PA and obesity in communities where African American and Hispanic or Latina reside when passing and/or enforcing public policies and amendments

    Moral Intuitions about Fault, Parenting, and Child Custody after Divorce

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    Allocations of child custody postdivorce are currently determined according to the best interest standard; that is, what is best for the child. Decisions about what is best for a child necessarily reflect cultural norms, at least in part. It is therefore useful as well as interesting to ask whether current understandings of the best interest standard align with moral intuitions of lay citizens asked to take the role of judge in hypothetical cases. Do factors such as whether 1 parent had an extramarital affair influence how respondents would award custody? In the current studies, a representative sample of citizens awaiting jury service was first given a neutral scenario portraying an “average” family. Almost 80% favored dividing custodial time equally between the 2 parents, replicating earlier findings. Then, in Study 1, they were given a second, test case, vignette in which either the mother or the father was said to have carried on an extramarital affair that “essentially ruined the marriage.” In Study 2, either the mother or the father was said to have sought the divorce, opposed by the other, simply because he or she “grew tired” of the marriage. For both test cases, our respondents awarded the offending parent significantly less parenting time; about half of our respondents in each Study. The findings indicate that many citizens feel both having an affair and growing tired of the marriage is sufficient cause to award decreased parenting time, reasons for which are explored in the discussion

    Lay Judgments about Child Custody after Divorce

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    In a pair of studies, we examine lay people’s judgments about how hypothetical cases involving child custody after divorce should be resolved. The respondents were citizens called to jury service in Pima County, Arizona. Study 1 found that both male and female respondents, if they were the judge, would most commonly award equally shared custody arrangements, as advocated by most fathers’ groups. However, if the predivorce child care had been divided disproportionately between the parents, this preference shifted, slightly but significantly, toward giving more time to the parent who had provided most of that care, consistent with the Approximation Rule advocated by the American Law Institute. Moreover, respondents judged that the arrangements prevailing in today’s court and legal environment would award equal custody considerably less often, and would thereby provide much less parenting time to fathers, than the respondents themselves would award. Study 2 found that respondents maintained their strong preference for equally shared custody even when there are very high levels of parental conflict for which the parents were equally to blame, but awarded substantially less time to the culpable parent when only one was the primary instigator of the parental conflict. The striking degree to which the public favors equal custody combined with their view that the current court system under-awards parenting time to fathers could account for past findings that the system is seriously slanted toward mothers, and suggests that family law may have a public relations problem
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