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

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

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

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

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

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

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

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

Measured and Self-reported Neighborhood Characteristics and Physical Activity Among African American Women

African American women are vulnerable to physical inactivity compared to white women. Measured and self-reported neighborhood characteristics may be associated with physical activity (PA), yet few studies have examined these factors among minority women. The purpose of this study was to investigate the associations of measured and self-reported neighborhood characteristics with individual PA. The Pedestrian Environment Data Scan was completed for 25% of randomly selected residential street segments within a 400 meter radius of each participants’ address. African American women (N=262, M age=44.4 yrs) completed interviewer administered questionnaires assessing self-reported neighborhood characteristics. PA was measured using the International Physical Activity Questionnaire (IPAQ) long (M MET minutes/week=2519) and accelerometry (M MVPA=19.0 min/day). Most women were obese (N=176, 67.2%; M BMI= 34.0). IPAQ PA was not associated with accelerometer PA. Bivariate correlations suggested relationships between greater measured pedestrian facility density and more IPAQ transportation PA , greater reported pedestrian facility density and more IPAQ leisure time PA, greater reported bicycle facility density and more IPAQ moderate PA and IPAQ total PA (ps\u3c.05). Simultaneous ecological multiple regression models demonstrated that reported pedestrian facility density (Beta=.138, t=2.181) and body fat percentage (Beta= -.089, t= -1.398) were associated with IPAQ leisure time PA (R²=.027; p=.04), reported bicycle facility density (Beta=.138, t=2.161) was associated with IPAQ moderate PA (R²=.019; p=.03), and reported bicycle facility density (Beta=.130, t=2.041) was associated with IPAQ total PA (R²= .017; p=.04). No measured or reported neighborhood characteristics were associated with accelerometer measured PA. Measured and reported built environment attributes are significantly associated with self-reported PA but may be mediated by weight status

Accuracy threshold for concatenated error detection in one dimension

Estimates of the quantum accuracy threshold often tacitly assume that it is possible to interact arbitrary pairs of qubits in a quantum computer with a failure rate that is independent of the distance between them. None of the many physical systems that are candidates for quantum computing possess this property. Here we study the performance of a concatenated error-detection code in a system that permits only nearest-neighbor interactions in one dimension. We make use of a new message-passing scheme that maximizes the number of errors that can be reliably corrected by the code. Our numerical results indicate that arbitrarily accurate universal quantum computation is possible if the probability of failure of each elementary physical operation is below approximately 10^{-5}. This threshold is three orders of magnitude lower than the highest known.Comment: 7 pages, 4 figures, now with error bar