509 research outputs found
The relative risk : parenting, poverty, and peers in the three city study of moving to opportunity
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2008.Includes bibliographical references (p. 265-274).This study shows how kin networks, parental monitoring, and housing mobility structure low-income adolescents' engagement in risky and delinquent behavior. I use ethnographic data from a mixed-method study of a randomized housing experiment: The Three City Study of Moving to Opportunity. The ethnography was conducted over 8 months in 2004-2005 with thirty-nine families, including fifty-two male and female adolescents (ages 11-23) in greater Boston, Los Angeles, and New York. Beginning in 1994, two-thirds of the families (members of the experimental complier group) relocated from public and assisted housing in high poverty neighborhoods to very low poverty neighborhoods, using a rental housing voucher and other program supports. The remaining one-third of the sample, a control group, continued to live in high poverty "project" neighborhoods. Using case-study logic, I examine how the content and location of adolescent's daily routines and social ties to friends and relatives are associated with their involvement in risky and delinquent behavior. I also examine the role of parental monitoring and housing mobility patterns in moderating exposure to risk.I find that for most adolescents in the experimental-complier group, the neighborhood of residence has not become the primary neighborhood of influence in that the former only partially structures their routines and important social relations. How parents manage their social relations, especially with kin, shapes their children's level of engagement in new residential neighborhoods, and involvement in risky and delinquent behavior.(cont.) Socializing with kin is risky because it brings youth back to dangerous neighborhood environments and because many youth stay connected to kin who are actively engaged in risky and delinquent behavior, including gang banging, drugs, and crime. Parenting moderates this exposure, but for some families, it does not change dramatically after relocation. These findings contribute to research on low-income housing policy and neighborhood effects by demonstrating the critical role of extended family networks, ongoing housing mobility, and multiple neighborhoods of influence in shaping exposure to risk. My policy recommendations include strategies to: help very low-income families who escape high-risk neighborhoods to stay out of them over time, and to manage the risk in their lives.Gretchen D. Weismann.Ph.D
Long-range Kondo signature of a single magnetic impurity
The Kondo effect, one of the oldest correlation phenomena known in condensed
matter physics, has regained attention due to scanning tunneling spectroscopy
(STS) experiments performed on single magnetic impurities. Despite the
sub-nanometer resolution capability of local probe techniques one of the
fundamental aspects of Kondo physics, its spatial extension, is still subject
to discussion. Up to now all STS studies on single adsorbed atoms have shown
that observable Kondo features rapidly vanish with increasing distance from the
impurity. Here we report on a hitherto unobserved long range Kondo signature
for single magnetic atoms of Fe and Co buried under a Cu(100) surface. We
present a theoretical interpretation of the measured signatures using a
combined approach of band structure and many-body numerical renormalization
group (NRG) calculations. These are in excellent agreement with the rich
spatially and spectroscopically resolved experimental data.Comment: 7 pages, 3 figures + 8 pages supplementary material; Nature Physics
(Jan 2011 - advanced online publication
Panoramic optical and near-infrared SETI instrument: prototype design and testing
The Pulsed All-sky Near-infrared Optical Search for ExtraTerrestrial
Intelligence (PANOSETI) is an instrument program that aims to search for fast
transient signals (nano-second to seconds) of artificial or astrophysical
origin. The PANOSETI instrument objective is to sample the entire observable
sky during all observable time at optical and near-infrared wavelengths over
300 - 1650 nm. The PANOSETI instrument is designed with a number of modular
telescope units using Fresnel lenses (0.5m) arranged on two geodesic
domes in order to maximize sky coverage. We present the prototype design
and tests of these modular Fresnel telescope units. This consists of the design
of mechanical components such as the lens mounting and module frame. One of the
most important goals of the modules is to maintain the characteristics of the
Fresnel lens under a variety of operating conditions. We discuss how we account
for a range of operating temperatures, humidity, and module orientations in our
design in order to minimize undesirable changes to our focal length or angular
resolution.Comment: 12 pages, 8 figures, 1 tabl
Cytogerontology since 1881: A reappraisal of August Weismann and a review of modern progress
Cytogerontology, the science of cellular ageing, originated in 1881 with the prediction by August Weismann that the somatic cells of higher animals have limited division potential. Weismann's prediction was derived by considering the role of natural selection in regulating the duration of an organism's life. For various reasons, Weismann's ideas on ageing fell into neglect following his death in 1914, and cytogerontology has only reappeared as a major research area following the demonstration by Hayflick and Moorhead in the early 1960s that diploid human fibroblasts are restricted to a finite number of divisions in vitro.
In this review we give a detailed account of Weismann's theory, and we reveal that his ideas were both more extensive in their scope and more pertinent to current research than is generally recognised. We also appraise the progress which has been made over the past hundred years in investigating the causes of ageing, with particular emphasis being given to (i) the evolution of ageing, and (ii) ageing at the cellular level. We critically assess the current state of knowledge in these areas and recommend a series of points as primary targets for future research
Come back Marshall, all is forgiven? : Complexity, evolution, mathematics and Marshallian exceptionalism
Marshall was the great synthesiser of neoclassical economics. Yet with his qualified assumption of self-interest, his emphasis on variation in economic evolution and his cautious attitude to the use of mathematics, Marshall differs fundamentally from other leading neoclassical contemporaries. Metaphors inspire more specific analogies and ontological assumptions, and Marshall used the guiding metaphor of Spencerian evolution. But unfortunately, the further development of a Marshallian evolutionary approach was undermined in part by theoretical problems within Spencer's theory. Yet some things can be salvaged from the Marshallian evolutionary vision. They may even be placed in a more viable Darwinian framework.Peer reviewedFinal Accepted Versio
Learning From Early Attempts to Generalize Darwinian Principles to Social Evolution
Copyright University of Hertfordshire & author.Evolutionary psychology places the human psyche in the context of evolution, and addresses the Darwinian processes involved, particularly at the level of genetic evolution. A logically separate and potentially complementary argument is to consider the application of Darwinian principles not only to genes but also to social entities and processes. This idea of extending Darwinian principles was suggested by Darwin himself. Attempts to do this appeared as early as the 1870s and proliferated until the early twentieth century. But such ideas remained dormant in the social sciences from the 1920s until after the Second World War. Some lessons can be learned from this earlier period, particularly concerning the problem of specifying the social units of selection or replication
Maritime Heritage in the Sultanate of Oman
With over 1700 km of coastline, the inhabitants of Oman have had a deep and enduring relationship with the sea for millennia. Located between the Arabian Gulf and the western Indian Ocean, its fishermen have relied on the sea for sustenance. Its mariners were involved in developing long-distance maritime trade from at least the Bronze Age and continued sailing the monsoonal trade routes well into the twentieth century. Periodically, its rulers have established maritime polities extending to Zanzibar and the Makran coast, creating sea-based migrations in the process. With such a rich and enduring seafaring past, it is therefore not surprising that the modern nation-state of Oman has had an active interest in studying and preserving its MUCH.This chapter explores the historical sources, archaeological finds and experimental activities that have allowed researchers to understand Omanâs maritime past and contribute to its current efforts to conserve and showcase its rich maritime connections
Prevention of Hepatic Steatosis and Hepatic Insulin Resistance by Knockdown of cAMP Response Element-Binding Protein
SummaryIn patients with poorly controlled type 2 diabetes mellitus (T2DM), hepatic insulin resistance and increased gluconeogenesis contribute to fasting and postprandial hyperglycemia. Since cAMP response element-binding protein (CREB) is a key regulator of gluconeogenic gene expression, we hypothesized that decreasing hepatic CREB expression would reduce fasting hyperglycemia in rodent models of T2DM. In order to test this hypothesis, we used a CREB-specific antisense oligonucleotide (ASO) to knock down CREB expression in liver. CREB ASO treatment dramatically reduced fasting plasma glucose concentrations in ZDF rats, ob/ob mice, and an STZ-treated, high-fat-fed rat model of T2DM. Surprisingly, CREB ASO treatment also decreased plasma cholesterol and triglyceride concentrations, as well as hepatic triglyceride content, due to decreases in hepatic lipogenesis. These results suggest that CREB is an attractive therapeutic target for correcting both hepatic insulin resistance and dyslipidemia associated with nonalcoholic fatty liver disease (NAFLD) and T2DM
Long-Lost Relative Claims Orphan Gene: oskar in a Wasp
Organismic and Evolutionary Biolog
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