2,999 research outputs found

    Infrared Imaging of the Gravitational Lens PG 1115+080 with the Subaru Telescope

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    We present high spatial resolution images of the gravitational-lens system PG 1115+080 taken with the near-infrared camera (CISCO) on the Subaru telescope. The FWHM of the combined image is 0.′′320.''32 in the K′K'-band, yielding spatial resolution of 0.′′140.''14 after a deconvolution procedure. This is a first detection of an extended emission adjacent to the A1/A2 components, indicating the presence of a fairly bright emission region with a characteristic angular radius of ∼\sim 5 mas (40 pc). The near-infrared image of the Einstein ring was extracted in both the JJ and K′K' bands. The J−K′J-K' color is found to be significantly redder than that of a synthetic model galaxy with an age of 3 Gyr, the age of the universe at the quasar redshift.Comment: 11 pages, 6 figures. Accepted for publication in PASJ(2000

    Composition and energy spectra of cosmic ray nuclei above 500 GeV/nucleon from the JACEE emulsion chambers

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    The composition and energy spectra of charge groups (C - 0), (Ne - S), and (Z approximately 17) above 500 GeV/nucleon from the experiments of JACEE series balloonborne emulsion chambers are reported. Studies of cosmic ray elemental composition at higher energies provide information on propagation through interstellar space, acceleration mechanisms, and their sources. One of the present interests is the elemental composition at energies above 100 GeV/nucleon. Statistically sufficient data in this energy region can be decisive in judgment of propagation models from the ratios of SECONDARY/PRIMARY and source spectra (acceleration mechanism), as well as speculative contributions of different sources from the ratios of PRIMARY/PRIMARY. At much higher energies, i.e., around 10 to the 15th power eV, data from direct observation will give hints on the knee problem, as to whether they favor an escape effect possibly governed by magnetic rigidity above 10 to the 16th power eV

    Primary cosmic ray spectra in the range 20-60 GeV/n

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    Energy spectra for primary cosmic rays C-Fe above 20 GeV/n were measured on a balloon flight from Greenville S.C. in June 1982 with a hybrid electronic counter-emulsion chamber experiment. Fluxes above the atmosphere appear in general agreement with previously published values. The heavy events included in this data will be used along with the JACEE passive chamber data to provide a heavy composition direct measurement from 10 to the 12th power to approximately 10 to the 15th power eV total energy

    The response of a scintillation counter below an emulsion chamber to heavy nucleus interactions in the chamber

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    In 1982 a hybrid electronic counter-emulsion chamber experiment was flown on a balloon to study heavy nucleus interactions in the 20 to approximately 100 GeV/AMU energy range. A gas Cerenkov counter, two solid Cerenkov counters, and a proportional counter hodoscope gave the primary energy, the primary charge and the trajectory of the particles, respectively. Using the trajectory information cosmic ray nuclei of Z 10 were found reliably and efficiently, and interaction characteristics of the Fe group nuclei were measured in the chamber. A plastic scintillator below the emulsion chamber responded to showers resulting from interactions in the chamber and to noninteracting nuclei. Data on the response of the counter have been compared with simulations of hadronic-electromagnetic cascades to derive the average neutral energy fraction released by the heavy interactions, and to predict the performance of this kind of counter at higher energies. For the interacting events of highest produced particles multiplicity comparison between various simulations and the shower counter signal have been made

    Generalized Taub-NUT metrics and Killing-Yano tensors

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    A necessary condition that a St\"ackel-Killing tensor of valence 2 be the contracted product of a Killing-Yano tensor of valence 2 with itself is re-derived for a Riemannian manifold. This condition is applied to the generalized Euclidean Taub-NUT metrics which admit a Kepler type symmetry. It is shown that in general the St\"ackel-Killing tensors involved in the Runge-Lenz vector cannot be expressed as a product of Killing-Yano tensors. The only exception is the original Taub-NUT metric.Comment: 14 pages, LaTeX. Final version to appear in J.Phys.A:Math.Ge

    Pressure natriuresis in isolated kidneys from hypertension-prone and hypertension-resistant rats (Dahl rats)11Dr. Dahl, with whom we were collaborating, died just as this work was beginning. We wish to dedicate this paper to his memory.

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    Pressure natriuresis in isolated kidneys from hypertension-prone and hypertension-resistant rats (Dahl rats). Dahl described a strain of rats with genetically controlled propensities for hypertension. Chronic excess salt feeding increased blood pressure in sensitive (S) rats, whereas resistant rats (R) remain normotensive. We tested the pressure natriuretic function (urinary sodium excretion versus perfusion pressure) in isolated kidneys perfused with a cellular medium: in sodium-restricted normotensive sensitive (S0) and resistant (R0) animals; in sensitive rats receiving a high-salt diet for 3 weeks (S3); and in both S and R animals exposed to excess sodium for 7 weeks (R7 and S7). The aim of these studies was to determine if a preset alteration of the pressure natriuretic function might be present in S animals prior to the development of hypertension. Systolic blood pressure in S0, S3, and S7animals were 123 ± 4, 136 ± 2, and 162 ± 4mm Hg, respectively, whereas that of R0 and R7 were 121 ± 5 and 126 ± 5mm Hg. An increase of the perfusion pressure of isolated kidneys from 105 to 185mm Hg in stepwise fashion resulted in a pressure natriuresis whose slope was similar in R0 and S0 animals. Of interest was that the pressure natriuretic function slope of kidneys from R0(low sodium) and R7 (high sodium) rats was as predicted by the Guyton system analysis of normal blood pressure control. Micropuncture of the proximal nephrons demonstrated that the origin of the natriuresis resulted from a site beyond the accessible proximal tubule. Results from S7 kidneys contrasted with all others in that the natriuretic response was depressed (P < 0.01), which resulted from significantly lower filtration rates at higher perfusion pressures. We concluded (1) in normal R rats, the pressure natriuretic function is that predicted by the Guyton hypothesis, (2) Dahl S animals have no preset abnormality of this function until hypertension is present for some time, and (3) a depression of the pressure natriuretic function may aggravate hypertension in S rats once high blood pressure has persisted.Natriurèse de pression dans les reins isolés provenant de rats de Dahl sensibles ou résistants à l'hypertension. Dahl a décrit une souche de rats ayant une propension génétique à l'hypertension. L'administration d'une alimentation riche en sel augmente la pression artérielle chez les rats sensibles (S) alors que les rats résistants (R) restent normotendus. Nous avons étudié la natriurèse de pression (excrétion urinaire de sodium en fonction de la pression de perfusion) dans des reins isolés perfuses avec un milieu cellulaire provenant de rats normotendus S0 et R0 soumis à une restriction de sodium, de rats sensibles ayant reçu une alimentation riche en sel pendant trois semaines (S3) et de rats S et R exposés à un excès de sel pendant 7 semaines (R7 et S7). Le but de ces études est d'établir l'existence éventuelle d'une modification de la relation pression natriurèse avant le développement de l'hypertension. Les pressions systoliques des rats, S0, S3, et S7 étaient de 123 ± 4, 136 ± 2, et 162 ± 4mm Hg, respectivement, alors que celles de R0 et R7 étaient de 121 ± 5 et 126 ± 5mm Hg. Une augmentation de la pression de perfusion de reins isolés de 105 à 185mm Hg, par paliers, a eu pour résultat une natriurèse de pression dont la pente était la même chez R0 et S0. Il est intéressant de remarquer que la pente de cette relation pour les reins R0 (sodium bas) et R7 (sodium élevé) est celle qui est prévue par l'analyse de Guyton du contrôle normal de la pression artérielle. Des microponctions des néphrons proximaux ont montré que l'origine de la natriurèse est en aval du tuble proximal accessible. Les résultats des reins S7 ont été différents de tous les autres en ce sens que la réponse natriurétique a été déprimée (P < 0,001) en raison des débits de filtration significativement plus faibles à des pressions de perfusion plus élevées. Nous concluons: (1) chez les rats R normaux la relation pression-natriurèse est celle prédite par l'hypothèse de Guyton; (2) les animaux Dahl S n'ont pas d'anomalie préexistante de cette fonction; (3) une dépression de la relation natirurèse-pression peut aggraver l'hypertension chez les rats S une fois que la pression artérielle élevée a persisté

    muCool: A novel low-energy muon beam for future precision experiments

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    Experiments with muons (μ+\mu^{+}) and muonium atoms (μ+e−\mu^{+}e^{-}) offer several promising possibilities for testing fundamental symmetries. Examples of such experiments include search for muon electric dipole moment, measurement of muon g−2g-2 and experiments with muonium from laser spectroscopy to gravity experiments. These experiments require high quality muon beams with small transverse size and high intensity at low energy. At the Paul Scherrer Institute, Switzerland, we are developing a novel device that reduces the phase space of a standard μ+\mu^{+} beam by a factor of 101010^{10} with 10−310^{-3} efficiency. The phase space compression is achieved by stopping a standard μ+\mu^{+} beam in a cryogenic helium gas. The stopped μ+\mu^{+} are manipulated into a small spot with complex electric and magnetic fields in combination with gas density gradients. From here, the muons are extracted into the vacuum and into a field-free region. Various aspects of this compression scheme have been demonstrated. In this article the current status will be reported.Comment: 8 pages, 5 figures, TCP 2018 conference proceeding

    Dioxins levels in human blood after implementation of measures against dioxin exposure in Japan

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    Background: Over the past few decades, the Japanese Ministry of the Environment has been biomonitoring dioxins in the general Japanese population and, in response to public concerns, has taken measures to reduce dioxin exposure. The objectives of this study were to assess the current dioxin dietary intake and corresponding body burden in the Japanese and compare Japanese dioxin data from 2011 to 2016 and 2002–2010 surveys. We also examined the relationship between blood dioxins and health parameters/clinical biomarkers. Methods: From 2011 to 2016, cross-sectional dioxin surveys were conducted on 490 Japanese (242 males and 248 females, aged 49.9 ± 7.6 years) from 15 Japanese prefectures. Blood (n = 490) and food samples (n = 90) were measured for 29 dioxin congeners including polychlorinated dibenzo-para-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs) using gas chromatography coupled with high-resolution mass spectrometry. Using the 2006 World Health Organization toxic equivalence factors, the toxic equivalents (TEQs) were calculated. Clinical biomarkers and anthropometric parameters were also measured and information on lifestyle behaviours collected. Data imputations were applied to account for blood dioxins below the detection limit. Results: The median (95% confidence interval or CI) blood levels and dioxin dietary intake was respectively 9.4 (8.8–9.9) pg TEQ/g lipid and 0.3 (0.2–0.4) pg TEQ/kg body weight/day. The median blood dioxin level in the 2011–2016 survey was found to have decreased by 41.3% compared to the 2002–2010 surveys. Participants who were older were found to be more likely to have higher dioxin levels. Blood dioxins were also significantly associated with body mass index, triglycerides, docosahexaenoic acid, eicosapentaenoic acid, and dihomo-gamma-linoleic acid levels in blood. Furthermore, associations between blood dioxin and dietary dioxin intake were evident in the unadjusted models. However, after adjusting for confounders, blood dioxins were not found to be associated with dietary dioxin intake. Conclusions: Blood dioxin levels declined over the past decade. This study showed that the measures and actions undertaken in Japan have possibly contributed to these reductions in the body burden of dioxins in the Japanese population
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