1,986 research outputs found

    The Equivalence Principle in the Non-baryonic Regime

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    We consider the empirical validity of the equivalence principle for non-baryonic matter. Working in the context of the TH\epsilon\mu formalism, we evaluate the constraints experiments place on parameters associated with violation of the equivalence principle (EVPs) over as wide a sector of the standard model as possible. Specific examples include new parameter constraints which arise from torsion balance experiments, gravitational red shift, variation of the fine structure constant, time-dilation measurements, and matter/antimatter experiments. We find several new bounds on EVPs in the leptonic and kaon sectors.Comment: 22 pages, late

    Quantum fluctuations for drag free geodesic motion

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    The drag free technique is used to force a proof mass to follow a geodesic motion. The mass is protected from perturbations by a cage, and the motion of the latter is actively controlled to follow the motion of the proof mass. We present a theoretical analysis of the effects of quantum fluctuations for this technique. We show that a perfect drag free operation is in principle possible at the quantum level, in spite of the back action exerted on the mass by the position sensor.Comment: 4 pages, 1 figure, RevTeX, minor change

    Neutron star in presence of torsion-dilaton field

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    We develop the general theory of stars in Saa's model of gravity with propagating torsion and study the basic stationary state of neutron star. Our numerical results show that the torsion force decreases the role of the gravity in the star configuration leading to significant changes in the neutron star masses depending on the equation of state of star matter. The inconsistency of the Saa's model with Roll-Krotkov-Dicke and Braginsky-Panov experiments is discussed.Comment: 29 pages, latex, 24 figures, final version. Added: 1)comments on different possible mass definitions; 2)new sections: a)the inconsistency of the Saa's model with Roll-Krotkov-Dicke and Braginsky-Panov experiments; b)stability analysis via catastrophe theory; 3)new figers added and some figures replaced. 4)new reference

    Testing the Principle of Equivalence by Solar Neutrinos

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    We discuss the possibility of testing the principle of equivalence with solar neutrinos. If there exists a violation of the equivalence principle quarks and leptons with different flavors may not universally couple with gravity. The method we discuss employs a quantum mechanical phenomenon of neutrino oscillation to probe into the non-universality of the gravitational couplings of neutrinos. We develop an appropriate formalism to deal with neutrino propagation under the weak gravitational fields of the sun in the presence of the flavor mixing. We point out that solar neutrino observation by the next generation water Cherenkov detectors can improve the existing bound on violation of the equivalence principle by 3-4 orders of magnitude if the nonadiabatic Mikheyev-Smirnov-Wolfenstein mechanism is the solution to the solar neutrino problem.Comment: Latex, 17 pages + 6 uuencoded postscript figures, KEK-TH-396, TMUP-HEL-9402 (unnecessary one reference was removed

    Different phytase levels and energy densities in broiler diets on performance, nutrient digestibility, and bone integrity from 28 to 35 days of age.

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    Abstract: The study was carried out with the objective of evaluating the effects of using phytase levels at different energy densities in the diet of broilers, from 28 to 35 days of age. The experimental diets contained increasing levels of apparent metabolizable energy corrected for nitrogen balance and different levels of phytase. Growth performance variables, nutrient digestibility, as well as variables related to bone integrity were examined. Diets containing 500 FTU/kg in combination with 3150kcal.kg-1 of AMEn resulted in better growth performance. Supplementation with 500 and 1000 FTU/kg in the diets provide better coefficients of apparent and ileal digestibility of calcium and phosphorus, but negatively influence the deposition of calcium, phosphorus, dry matter, and ash in the tibia, in addition to adversely affecting the breakage and area of these bones in broilers. Bone length and the levels of magnesium and zinc present in the tibias were not influenced by the energy and phytase levels of the diets. There is no interaction between the different energetic densities and the phytase doses in the variables analyzed in the studied period. Increasing the energy density of diets resulted in improved apparent and ileal digestibility for most nutrients. Resumo: O estudo foi realizado com o objetivo de avaliar os efeitos da utilização de níveis de fitase em diferentes densidades energéticas na dieta de frangos de corte, no período de 28 a 35 dias de idade. As dietas experimentais contiveram níveis crescentes de energia metabolizável aparente corrigida para balanço de nitrogênio e diferentes níveis de fitase. Foram avaliadas variáveis de desempenho zootécnico, digestibilidade de nutrientes e variáveis relacionadas à integridade óssea. Dietas contendo 500 FTU/kg de fitase em combinação com 3150kcal.kg-1 de EMAn resultam em melhor desempenho zootécnico. A suplementação com 500 e 1000 FTU/kg nas dietas propicia melhores coeficientes de digestibilidade aparente e ileal do cálcio e do fósforo, mas influencia negativamente na deposição de cálcio, fósforo, matéria seca e cinzas das tíbias, além de afetar adversamente a quebra e a área desses ossos em frangos de corte. O comprimento do osso e os níveis de magnésio e zinco presentes nas tíbias não são influenciados pelos níveis energéticos e de fitase das dietas. Não há interação entre as diferentes densidades energéticas e as doses de fitase nas variáveis analisadas no período estudado. O aumento da densidade energética das dietas resulta em melhora na digestibilidade aparente e ileal para a maioria dos nutrientes

    Prevalence and Predictors of Urinary Tract Infection and Severe Malaria Among Febrile Children Attending Makongoro Health Centre in Mwanza City, North-Western Tanzania.

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    In malaria endemic areas, fever has been used as an entry point for presumptive treatment of malaria. At present, the decrease in malaria transmission in Africa implies an increase in febrile illnesses related to other causes among underfives. Moreover, it is estimated that more than half of the children presenting with fever to public clinics in Africa do not have a malaria infection. Thus, for a better management of all febrile illnesses among under-fives, it becomes relevant to understand the underlying aetiology of the illness. The present study was conducted to determine the relative prevalence and predictors of P. falciparum malaria, urinary tract infections and bacteremia among under-fives presenting with a febrile illness at the Makongoro Primary Health Centre, North-Western Tanzania. From February to June 2011, a cross-sectional analytical survey was conducted among febrile children less than five years of age. Demographic and clinical data were collected using a standardized pre-tested questionnaire. Blood and urine culture was done, followed by the identification of isolates using in-house biochemical methods. Susceptibility patterns to commonly used antibiotics were investigated using the disc diffusion method. Giemsa stained thin and thick blood smears were examined for any malaria parasites stages. A total of 231 febrile under-fives were enrolled in the study. Of all the children, 20.3% (47/231, 95%CI, 15.10-25.48), 9.5% (22/231, 95%CI, 5.72-13.28) and 7.4% (17/231, 95%CI, 4.00-10.8) had urinary tract infections, P. falciparum malaria and bacteremia respectively. In general, 11.5% (10/87, 95%CI, 8.10-14.90) of the children had two infections and only one child had all three infections. Predictors of urinary tract infections (UTI) were dysuria (OR = 12.51, 95% CI, 4.28-36.57, P < 0.001) and body temperature (40-41 C) (OR = 12.54, 95% CI, 4.28-36.73, P < 0.001). Predictors of P. falciparum severe malaria were pallor (OR = 4.66 95%CI, 1.21-17.8, P = 0.025) and convulsion (OR = 102, 95% CI, 10-996, P = 0.001). Escherichia coli were the common gram negative isolates from urine (72.3%, 95% CI, 66.50-78.10) and blood (40%, 95%CI, and 33.70-46.30). Escherichia coli from urine were 100% resistant to ampicillin, 97% resistant to co-trimoxazole, 85% resistant to augmentin and 32.4% resistant to gentamicin; and they were 100%, 91.2% and 73.5% sensitive to meropenem, ciprofloxacin and ceftriaxone respectively. Urinary tract infection caused by multi drug resistant Escherichia coli was the common cause of febrile illness in our setting. Improvement of malaria diagnosis and its differential diagnosis from other causes of febrile illnesses may provide effective management of febrile illnesses among children in Tanzania
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