364 research outputs found

    Gravito-electromagnetic analogies

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    We reexamine and further develop different gravito-electromagnetic (GEM) analogies found in the literature, and clarify the connection between them. Special emphasis is placed in two exact physical analogies: the analogy based on inertial fields from the so-called "1+3 formalism", and the analogy based on tidal tensors. Both are reformulated, extended and generalized. We write in both formalisms the Maxwell and the full exact Einstein field equations with sources, plus the algebraic Bianchi identities, which are cast as the source-free equations for the gravitational field. New results within each approach are unveiled. The well known analogy between linearized gravity and electromagnetism in Lorentz frames is obtained as a limiting case of the exact ones. The formal analogies between the Maxwell and Weyl tensors are also discussed, and, together with insight from the other approaches, used to physically interpret gravitational radiation. The precise conditions under which a similarity between gravity and electromagnetism occurs are discussed, and we conclude by summarizing the main outcome of each approach.Comment: 60 pages, 2 figures. Improved version (compared to v2) with some re-write, notation improvements and a new figure that match the published version; expanded compared to the published version to include Secs. 2.3 and

    The GINGER Project

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    GINGER (Gyroscopes IN General Relativity) is a project aiming at measuring the Lense-Thirring effect, at 1% level, with an experiment on earth. It is based on an array of ring-lasers, which are the most sensitive inertial sensors to measure the rotation rate of the Earth. The GINGER project is still under discussion; the experiment G-GranSasso is an R&D experiment financed by INFN Group II, it is studying the key points of GINGER and at the same time developing prototypes. In the following the signal coming out of a ring-laser and the present sensitivity are described.The prototypes GP2 and GINGERino and the preliminary results are reported. This project is inter-disciplinary since ring-lasers provide informations for the fast variation of the earth rotation rate, they are used for the rotational seismology and for top sensitivity angle metrology

    Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects

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    BACKGROUND: Despite a growing literature on the efficacy of behavioral weight loss interventions, we still know relatively little about the long terms effects they have on HRQL. Therefore, we conducted a study to investigate the immediate post-intervention (6 months) and long-term (12 and 24 months) effects of clinically based weight management programs on HRQL. METHODS: We conducted a randomized clinical trial in which all participants completed a 6 month clinical weight loss program and were randomized into two 6-month extended care groups. Participants then returned at 12 and 24 months for follow-up assessments. A total of 144 individuals (78% women, M age = 50.2 (9.2) yrs, M BMI = 32.5 (3.8) kg/m(2)) completed the 6 month intervention and 104 returned at 24 months. Primary outcomes of weight and HRQL using the SF-36 were analyzed using multivariate repeated measures analyses. RESULTS: There was complete data on 91 participants through the 24 months of the study. At baseline the participants scored lower than U.S. age-specific population norms for bodily pain, vitality, and mental health. At the completion of the 6 month clinical intervention there were increases in the physical and mental composite measures as well as physical functioning, general health, vitality, and mental health subscales of the SF-36. Despite some weight regain, the improvements in the mental composite scale as well as the physical functioning, vitality, and mental health subscales were maintained at 24 months. There were no significant main effects or interactions by extended care treatment group or weight loss group (whether or not they maintained 5% loss at 24 months). CONCLUSION: A clinical weight management program focused on behavior change was successful in improving several factors of HRQL at the completion of the program and many of those improvements were maintained at 24 months. Maintaining a significant weight loss (> 5%) was not necessary to have and maintain improvements in HRQL

    f(R) theories

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    Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in Relativity, Published version, Comments are welcom

    Search for the standard model Higgs boson at LEP

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    Vitamin D pathway gene polymorphisms, diet, and risk of postmenopausal breast cancer: a nested case-control study

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    INTRODUCTION: Vitamin D receptor (VDR) polymorphisms have been inconsistently associated with breast cancer risk. Whether risk is influenced by polymorphisms in other vitamin D metabolism genes and whether calcium or vitamin D intake modifies risk by genotype have not been evaluated. METHODS: We conducted a nested case-control study within the Cancer Prevention Study II Nutrition Cohort of associations between breast cancer and four VDR single-nucleotide polymorphisms (SNPs), Bsm1,Apa1,Taq1, and Fok1, a poly(A) microsatellite, and associated haplotypes (baTL and BAtS). We also examined one SNP in the 24-hydroxylase gene (CYP24A1) and two in the vitamin D-binding protein (group-specific component [GC]) gene. Participants completed a questionnaire on diet and medical history at baseline in 1992. This study includes 500 postmenopausal breast cancer cases and 500 controls matched by age, race/ethnicity, and date of blood collection. RESULTS: Incident breast cancer was not associated with any genotype examined. However, women with the Bsm1 bb SNP who consumed greater than the median intake of total calcium (≄902 mg/day) had lower odds of breast cancer compared to women with the Bb or BB genotype and less than the median calcium intake (odds ratio 0.61, 95% confidence interval 0.38 to 0.96; p(interaction )= 0.01). Similar interactions were observed for Taq1 (T allele) and the poly(A) (LL) repeat. CONCLUSION: We found no overall association between selected vitamin D pathway genes and postmenopausal breast cancer risk. However, certain VDR gene polymorphisms were associated with lower risk in women consuming high levels of calcium, suggesting that dietary factors may modify associations by VDR genotype

    The Use of Sexually Explicit Internet Material and Its Antecedents: A Longitudinal Comparison of Adolescents and Adults

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    An implicit assumption in research on adolescents’ use of sexually explicit internet material (SEIM) is that they may feel more attracted to such material than adults, given the “forbidden” character of SEIM for minors. However, systematic comparisons between adolescents’ and adults’ SEIM use and of its antecedents are missing. We conducted a two-wave panel survey among a nationally representative sample of 1,445 Dutch adolescents and a nationally representative sample of 833 Dutch adults. Adolescents’ and adults’ SEIM use was similar. When significant differences in the SEIM use occurred, they indicated that adults used SEIM more often than adolescents. Male adults were the most frequent users of SEIM. No difference in the antecedent structure of SEIM use emerged between adolescents and adults. In both groups, males, sensation seekers, as well as people with a not exclusively heterosexual orientation used SEIM more often. Among adolescents and adults, lower life satisfaction increased SEIM use. Our findings suggest that the frequency of SEIM use and its antecedents are largely the same among adolescents and adults

    Staphylococcus aureus enterotoxins induce IL-8 secretion by human nasal epithelial cells

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    BACKGROUND: Staphylococcus aureus produces a set of proteins which act both as superantigens and toxins. Although their mode of action as superantigens is well understood, little is known about their effects on airway epithelial cells. METHODS: To investigate this problem, primary nasal epithelial cells derived from normal and asthmatic subjects were stimulated with staphylococcal enterotoxin A and B (SEA and SEB) and secreted (supernatants) and cell-associated (cell lysates) IL-8, TNF-α, RANTES and eotaxin were determined by specific ELISAs. RESULTS: Non-toxic concentrations of SEA and SEB (0.01 ÎŒg/ml and 1.0 ÎŒg/ml) induced IL-8 secretion after 24 h of culture. Pre-treatment of the cells with IFN-Îł (50 IU/ml) resulted in a further increase of IL-8 secretion. In cells from healthy donors pretreated with IFN-Îł, SEA at 1.0 ÎŒg/ml induced release of 1009 pg/ml IL-8 (733.0–1216 pg/ml, median (range)) while in cells from asthmatic donors the same treatment induced significantly higher IL-8 secretion – 1550 pg/ml (1168.0–2000.0 pg/ml p = 0.04). Normal cells pre-treated with IFN-Îł and then cultured with SEB at 1.0 ÎŒg/ml released 904.6 pg/ml IL-8 (666.5–1169.0 pg/ml). Cells from asthmatics treated in the same way produced significantly higher amounts of IL-8 – 1665.0 pg/ml (1168.0–2000.0 pg/ml, p = 0.01). Blocking antibodies to MHC class II molecules added to cultures stimulated with SEA and SEB, reduced IL-8 secretion by about 40% in IFN-Îł unstimulated cultures and 75% in IFN-Îł stimulated cultures. No secretion of TNF-α, RANTES and eotaxin was noted. CONCLUSION: Staphylococcal enterotoxins may have a role in the pathogenesis of asthma
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