8,469 research outputs found

    Luminance cues constrain chromatic blur discrimination in natural scene stimuli

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    Introducing blur into the color components of a natural scene has very little effect on its percept, whereas blur introduced into the luminance component is very noticeable. Here we quantify the dominance of luminance information in blur detection and examine a number of potential causes. We show that the interaction between chromatic and luminance information is not explained by reduced acuity or spatial resolution limitations for chromatic cues, the effective contrast of the luminance cue, or chromatic and achromatic statistical regularities in the images. Regardless of the quality of chromatic information, the visual system gives primacy to luminance signals when determining edge location. In natural viewing, luminance information appears to be specialized for detecting object boundaries while chromatic information may be used to determine surface properties

    Enhancing laser sideband cooling in one-dimensional optical lattices via the dipole interaction

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    We study resolved sideband laser cooling of a one-dimensional optical lattice with one atom per site, and in particular the effect of the dipole interaction between radiating atoms. For simplicity, we consider the case where only a single cooling laser is applied. We derive a master equation, and solve it in the limit of a deep lattice and weak laser driving. We find that the dipole interaction significantly changes the final temperature of the particles, increasing it for some phonon wavevectors and decreasing it for others. The total phonon energy over all modes is typically higher than in the non-interacting case, but can be made lower by the right choice of parameters

    Symplectic N and time reversal in frustrated magnetism

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    Identifying the time reversal symmetry of spins as a symplectic symmetry, we develop a large N approximation for quantum magnetism that embraces both antiferromagnetism and ferromagnetism. In SU(N), N>2, not all spins invert under time reversal, so we have introduced a new large N treatment which builds interactions exclusively out of the symplectic subgroup [SP(N)] of time reversing spins, a more stringent condition than the symplectic symmetry of previous SP(N) large N treatments. As a result, we obtain a mean field theory that incorporates the energy cost of frustrated bonds. When applied to the frustrated square lattice, the ferromagnetic bonds restore the frustration dependence of the critical spin in the Neel phase, and recover the correct frustration dependence of the finite temperature Ising transition.Comment: added reference

    Sunday Friends: The Working Alternative to Charity

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    Sunday Friends is a non-profit organization in San JosĂ©, California, that provides multiple activities for families who are in need of financial support. Given the particular location of the program, most families are Latino and bilingual. Participants and program volunteers form a community at an elementary school on a couple of scheduled Sundays each month. When family members participate in activities designed to educate, improve skills, and to give back to the larger community, they earn tickets that they can redeem for items that they need and want from the Sunday Friends store. Activities include healthy cooking projects, “Thank You Letter” writing, English-as-a-Second-Language programs, crafts, and education in nutrition and financial literacy. The program’s central focus is to empower families to break out of poverty. A specific guiding principal is the developmental assets approach promoted by the Search Institute in Minneapolis (http://www.search-institute.org/). This approach encourages individuals and organizations to work together toward a common goal of supporting the healthy development of all children and youth. Healthy development is conceptualized as consisting of the development of external assets (i.e., support, empowerment, boundaries and expectations, constructive activities) and internal assets (i.e., commitment to learning, positive values, social competencies, and positive identity). The 2009 evaluation’s primary focus was on whether Sunday Friends was succeeding at fostering developmental assets for children. Other relevant indicators of success were perceptions of program effectiveness, regard for program activities, and nutrition and healthy eating habits. Data were gathered from family members (adults and minors) during program activities using written surveys administered by volunteers to the research team (most of whom were bilingual). The families were recruited in person by program staff onsite. The questionnaires were written in English and Spanish (with the choice made by respondents). Sunday Friends volunteers were recruited to the study via email by Sunday Friends staff. They completed questionnaires through an online survey platform. In all, 74 parents or guardians, 67 children or youth, and 45 volunteers participated in the data collection. Across the three sets of surveys (parents or guardians, children or youth, and volunteers), there are fairly consistent results. The families and volunteers in the Sunday Friends program believe that Sunday Friends is effectively engaging them and meeting its goals. Overall, children and youth report positive experiences at Sunday Friends. On every dimension of psychological well-being, connectedness with others, and self-efficacy, the answers provided by children and youth indicate that Sunday Friends is promoting developmental assets. In addition, parents and guardians report that Sunday Friends has positive influences on their lives. The majority of measures, whether questions about self-efficacy, the effect of Sunday Friends on their children, or improved nutrition for their family, indicate that Sunday Friends is meeting its goals. Finally, volunteers agree that the program makes an important contribution to the lives of both children and adults. They also feel that Sunday Friends enhances their awareness of the community and contributes to making their personal lives more meaningful. The survey results presented here should be interpreted with caution because all persons surveyed were continuing participants in the program, and the cross-sectional data could not detect changes over time. Despite this caution, each group’s data and triangulation across family and volunteer surveys reveal that milestones are accomplished at Sunday Friends. It is safe to conclude that Sunday Friends’ community-based approach to empowering parents and youths is achieving its goals

    Hidden Home Videos: Surreptitious Video Surveillance in Divorce

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    In divorce court, often a very contentious and emotional court, parties frequently use what they can to gain the upper hand. The invention of new technology gives them an even wider arsenal. While tracking each other on the computer or checking phone records has become common, courts are now encountering instances where one spouse has placed hidden video cameras around the house to catch the other spouse doing something wrong. Under many state laws, courts have been forced to conclude that the surreptitious video recordings are not illegal. Perhaps more surprisingly, a few courts have concluded that the law either allows or requires the court to admit the recordings into evidence in divorce proceedings. This article examines the possible implications of allowing secret video recordings between spouses and the consequences of bringing these recordings into the courtroom. This article concludes with suggestions to limit the negative impact of these surreptitious video recordings

    Repeated supra-maximal sprint cycling with and without sodium bicarbonate supplementation induces endothelial microparticle release

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    Under normal homeostatic conditions, the endothelium releases microparticles (MP), which are known to increase under stressful conditions and in disease states. CD105 (endoglin) and CD106 (vascular cell adhesion molecule-1) are expressed on the surface of endothelial cells and increased expression in response to stress may be observed. A randomised-controlled double-blinded study aimed to examine the use of endothelial microparticles as a marker for the state of one’s endothelium, as well as whether maintaining acid-base homeostasis affects the release of these MP. This study tested seven healthy male volunteers, who completed a strenuous cycling protocol, with venous blood analysed for CD105+ and CD106+ MP by flow cytometry at regular intervals. Prior to each trial participants consumed either 0.3 g·kg-1 body mass of sodium bicarbonate (NaHCO3), or 0.045 g·kg-1 body mass of sodium chloride (NaCl). A significant rise in endothelial CD105+MP and CD106+MP (p < 0.05) was observed at 90 minutes post exercise. A significant trend was shown for these MP to return to resting levels 180 minutes post exercise in both groups. No significance was found between experimental groups, suggesting that maintaining acid-base variables closer to basal levels has little effect upon the endothelial stress response for this particular exercise mode. In conclusion, strenuous exercise is accompanied by MP release and the endothelium is able to rapidly recover in healthy individuals, whilst maintaining acid-base homeostasis does not attenuate the MP release from the endothelium after exercise

    Implications of a pre-exercise alkalosis-mediated attenuation of HSP72 on its response to a subsequent bout of exercise

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    The aim of this study was to investigate if a pre-exercise alkalosis-mediated attenuation of HSP72 had any effect on the response of the same stress protein after a subsequent exercise. Seven physically active males [25.0 ± 6.5 years, 182.1 ± 6.0 cm, 74.0 ± 8.3 kg, peak aerobic power (PPO) 316 ± 46 W] performed a repeated sprint exercise (EXB1) following a dose of 0.3 g kg⁻Âč body mass of sodium bicarbonate (BICARB), or a placebo of 0.045 g kg⁻Âč body mass of sodium chloride (PLAC). Participants then completed a 90-min intermittent cycling protocol (EXB2). Monocyte expressed HSP72 was significantly attenuated after EXB1 in BICARB compared to PLAC, however, there was no difference in the HSP72 response to the subsequent EXB2 between conditions. Furthermore there was no difference between conditions for measures of oxidative stress (protein carbonyl and HSP32). These findings confirm the sensitivity of the HSP72 response to exercise-induced changes in acid–base status in vivo, but suggest that the attenuated response has little effect upon subsequent stress in the same day

    The Abduction of Women in Barbaric Law

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