9,521 research outputs found

    Neighborhood income inequality

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    This paper offers a descriptive empirical analysis of the geographic pattern of income inequality within a sample of 359 US metropolitan areas between 1980 and 2000. Specifically, we decompose the variance of metropolitan area-level household income into two parts: one associated with the degree of variation among household incomes within neighborhoods - defined by block groups and tracts - and the other associated with the extent of variation among households in different neighborhoods. Consistent with previous work, the results reveal that the vast majority of a city’s overall income inequality - at least three quarters - is driven by within-neighborhood variation rather than between-neighborhood variation, although we find that the latter rose significantly during the 1980s, especially between block groups. We then identify a number of metropolitan area-level characteristics that are associated with both levels of and changes in the degree of each type of residential income inequality.Income distribution ; Income

    Using the CRISPR/Cas9 system to understand neuropeptide biology and regulation

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    Funding was provided by a Wellcome Trust ISSF starting grant (105625/Z/14/Z), Medical Research Scotland (PhD-719-2013), GW Pharmaceuticals (PhD-719-2013 - S.5242.001) and the BBSRC (BB/J012343/1).Peer reviewedPublisher PD

    Understanding and controlling the ingress of driven rain through exposed, solid wall masonry structures

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    Long term performance of historic buildings can be affected by many environmental factors, some of which become more apparent as the competence of the fabric deteriorates. Many tall historic buildings suffer from water ingress when exposed to driving rain conditions, particularly church towers in the south west of England. It is important to recognise that leakage can occur not only through flaws in the roof of a building but also through significant thicknesses of solid masonry. Identification of the most appropriate intervention requires an understanding of the way in which water might enter the structure and the assessment of potential repair options. While the full work schedule used an integrated assessment involving laboratory, field and archival work to assess the repairs which might be undertaken on these solid wall structures, this paper focuses on the laboratory work done to inform the writing of a Technical Advice Note on the effects of wind driven rain and moisture movement in historic structures (English Heritage, 2012). The laboratory work showed that grouting and rendering was effective at reducing water penetration without retarding drying rates, but that use of internal plastering also had a very beneficial effect

    Patterns of Activity Expressed by Juvenile Horseshoe Crabs

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    Adult American horseshoe crabs, Limulus polyphemus, possess endogenous circadian and circatidal clocks controlling visual sensitivity and locomotion, respectively. The goal of this study was to determine the types of activity rhythms expressed by juvenile horseshoe crabs (n = 24) when exposed to a 14:10 light/dark cycle (LD) for 10 days, followed by 10 days of constant darkness (DD). Horseshoe crab activity was recorded with a digital time-lapse video system that used an infrared-sensitive camera so animals could be monitored at night. In LD, 15 animals expressed daily patterns of activity, 6 displayed a circatidal pattern, and the remaining 3 were arrhythmic. Of the 15 animals with daily patterns of locomotion, 7 had a significant preference (P \u3c 0.05) for diurnal activity and 3 for nocturnal activity; the remainder did not express a significant preference for day or night activity. In DD, 13 horseshoe crabs expressed circatidal rhythms and 8 maintained a pattern of about 24 h. Although these results suggest the presence of a circadian clock influencing circatidal patterns of locomotion, these apparent circadian rhythms may actually represent the expression of just one of the two bouts of activity driven by the putative circalunidian clocks that control their tidal rhythms. Overall, these results indicate that, like adults, juvenile horseshoe crabs express both daily and tidal patterns of activity and that at least one, and maybe both, of these patterns is driven by endogenous clocks

    Age-related differences in the structural complexity of subcortical and ventricular structures

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    It has been well established that the volume of several subcortical structures decreases in relation to age. Different metrics of cortical structure (e.g., volume, thickness, surface area, and gyrification) have been shown to index distinct characteristics of interindividual differences; thus, it is important to consider the relation of age to multiple structural measures. Here, we compare age-related differences in subcortical and ventricular volume to those differences revealed with a measure of structural complexity, quantified as fractal dimensionality. Across 3 large data sets, totaling nearly 900 individuals across the adult lifespan (aged 18–94 years), we found greater age-related differences in complexity than volume for the subcortical structures, particularly in the caudate and thalamus. The structural complexity of ventricular structures was not more strongly related to age than volume. These results demonstrate that considering shape-related characteristics improves sensitivity to detect age-related differences in subcortical structures

    Cortical complexity as a measure of age-related brain atrophy

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    The structure of the human brain changes in a variety of ways as we age. While a sizeable literature has examined age-related differences in cortical thickness, and to a lesser degree, gyrification, here we examined differences in cortical complexity, as indexed by fractal dimensionality in a sample of over 400 individuals across the adult lifespan. While prior studies have shown differences in fractal dimensionality between patient populations and age-matched, healthy controls, it is unclear how well this measure would relate to age-related cortical atrophy. Initially computing a single measure for the entire cortical ribbon, i.e., unparcellated gray matter, we found fractal dimensionality to be more sensitive to age-related differences than either cortical thickness or gyrification index. We additionally observed regional differences in age-related atrophy between the three measures, suggesting that they may index distinct differences in cortical structure. We also provide a freely available MATLAB toolbox for calculating fractal dimensionality

    A Decade of Making Dreams into Reality: Lessons from the I Have A Dream Program

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    Ten years ago, Eugene Lang startled a graduating class of East Harlem sixth-graders by promising to pay for their college educations. He had been advised by their principal that most of the students would drop out before completing high school; Lang hoped the tuition promise would motivate them to stay in school. But Lang soon discovered he needed to provide more than money to make the distant prospect of college a reality for his students, whom he called Dreamers. To augment his promise, Lang rented a meeting space and hired Johnny Rivera, a young caseworker with a neighborhood social service organization, to coordinate support services for the Dreamers and their families. Over the next ten years, Lang and Rivera worked closely with the students, as mentors and motivators. Most importantly, they built caring, personal relationships with their Dreamers. The original inspiration of the scholarship promise, combined with a decade of guidance and support, produced striking results

    RS-34 (Peacekeeper Post Boost Propulsion System) Orbital Debris Application Concept Study

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    The Advanced Concepts Office (ACO) at the NASA Marshall Space Flight Center (MSFC) lead a study to evaluate the Rocketdyne produced RS-34 propulsion system as it applies to an orbital debris removal design reference mission. The existing RS-34 propulsion system is a remaining asset from the de-commissioned United States Air Force Peacekeeper ICBM program; specifically the pressure-fed storable bi-propellant Stage IV Post Boost Propulsion System. MSFC gained experience with the RS-34 propulsion system on the successful Ares I-X flight test program flown in the Ares I-X Roll control system (RoCS). The heritage hardware proved extremely robust and reliable and sparked interest for further utilization on other potential in-space applications. Subsequently, MSFC is working closely with the USAF to obtain all the remaining RS-34 stages for re-use opportunities. Prior to pursuit of securing the hardware, MSFC commissioned the Advanced Concepts Office to understand the capability and potential applications for the RS-34 Phoenix stage as it benefits NASA, DoD, and commercial industry. Originally designed, the RS-34 Phoenix provided in-space six-degrees-of freedom operational maneuvering to deploy multiple payloads at various orbital locations. The RS-34 Concept Study, preceded by a utilization study to understand how the unique capabilities of the RS-34 Phoenix and its application to six candidate missions, sought to further understand application for an orbital debris design reference mission as the orbital debris removal mission was found to closely mimic the heritage RS-34 mission. The RS-34 Orbital Debris Application Concept Study sought to identify multiple configurations varying the degree of modification to trade for dry mass optimization and propellant load for overall capability and evaluation of several candidate missions. The results of the RS-34 Phoenix Utilization Study show that the system is technically sufficient to successfully support all of the missions analyzed. The results and benefits of the RS-34 Orbital Debris Application Concept Study are presented in this paper
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