535 research outputs found

    The catalogue of the discrete sources in the declination range from -13 deg to -2 deg

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    The results of the discrete source measurements with declinations -13 deg or = delta or = -2 deg and right ascensions 0 sub h + 24 sub h are given and were obtained as part of the systematic decametric survey of the celestial sphere with the rotatiotelecope UTR-2. Three hundred sixteen sources were found in the given declination range, four of which were observed for the first time. The source coordinates measured in the survey were compared with those from the 4th Cambridge survey at 178 MHz and the Parkes survey at 408 MHz

    Excitation of Spin Waves in Superconducting Ferromagnets

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    This Letter presents a theoretical analysis of propagation of spin waves in a superconducting ferromagnet. The surface impedance was calculated for the case when the magnetization is normal to the sample surface. We found the frequencies at which the impedance and the power absorption have singularities related to the spin wave propagation, and determined the form of these singularities. With a suitable choice of parameters, there is a frequency interval in which two propagating spin waves of the same circular polarization are generated, one of them having a negative group velocity.Comment: 4 pages, 2 figures, submitted to PR

    RC J1148+0455 identification: gravitational lens or group of galaxies ?

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    The structure of the radio source RC B1146+052 of the ``Cold'' catalogue is investigated by data of the MIT-GB-VLA survey at 4850 MHz. This source belongs to the steep spectrum radio sources subsample of the RC catalogue. Its spectral index is α\alpha = -1.04. The optical image of this source obtained with 6m telescope is analysed. The radio source center is situated in a group of 8 galaxies of about 24m^m in the R-filter. The possible explanations of the complex structure of radio components are considered.Comment: 6 pages, 5 figures, uses psfig.sty. This was the poster as presented on Gamow Memorial Internat. Conference GMIC'99 "Early Universe: Cosmological Problems and Instrumental Technologies" in St.Petersburg, 23-27 Aug., 1999. Submitted to Proceedings to be published in A&A Transaction

    Magnetoresistive study of antiferromagnetic--weak ferromagnetic transition in single-crystal La2_{2}CuO4+δ_{4+\delta}

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    The resistive measurements were made to study the magnetic field-induced antiferromagnetic (AF) - weak ferromagnetic (WF) transition in La2_2CuO4_4 single-crystal. The magnetic field (DC or pulsed) was applied normally to the CuO2_2 layers. The transition manifested itself in a drastic decrease of the resistance in critical fields of ~5-7 T. The study is the first to display the effect of the AF -WF transition on the conductivity of the La2_2CuO4_4 single-crystal in the parallel - to - CuO2_2 layers direction. The results provide support for the 3-dimensional nature of the hopping conduction of this layered oxide.Comment: 8 pages, 7 figures, RevTe

    Vortex shear effects in layered superconductors

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    Motivated by recent transport and magnetization measurements in BSCCO samples [B. Khaykovich et. al., Phys. Rev. B 61, R9261 (2000)], we present a simple macroscopic model describing effects of inhomogeneous current distribution and shear in a layered superconductor. Parameters of the model are deduced from a microscopic calculation. Our model accounts for the strong current non-linearities and the re-entrant temperature dependence observed in the experiment.Comment: 11 pages, 7 figures, submitted to Phys. Rev.

    Prevalence and correlates of depressive disorders in people with Type 2 diabetes: results from the International Prevalence and Treatment of Diabetes and Depression (INTERPRET‐DD) study, a collaborative study carried out in 14 countries

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    Aims To assess the prevalence and management of depressive disorders in people with Type 2 diabetes in different countries. Methods People with diabetes aged 18–65 years and treated in outpatient settings were recruited in 14 countries and underwent a psychiatric interview. Participants completed the Patient Health Questionnaire and the Problem Areas in Diabetes scale. Demographic and medical record data were collected. Results A total of 2783 people with Type 2 diabetes (45.3% men, mean duration of diabetes 8.8 years) participated. Overall, 10.6% were diagnosed with current major depressive disorder and 17.0% reported moderate to severe levels of depressive symptomatology (Patient Health Questionnaire scores >9). Multivariable analyses showed that, after controlling for country, current major depressive disorder was significantly associated with gender (women) (PPPPP<0.0001). The proportion of those with either current major depressive disorder or moderate to severe levels of depressive symptomatology who had a diagnosis or any treatment for their depression recorded in their medical records was extremely low and non-existent in many countries (0–29.6%). Conclusions Our international study, the largest of this type ever undertaken, shows that people with diabetes frequently have depressive disorders and also significant levels of depressive symptoms. Our findings indicate that the identification and appropriate care for psychological and psychiatric problems is not the norm and suggest a lack of the comprehensive approach to diabetes management that is needed to improve clinical outcomes

    The 74MHz System on the Very Large Array

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    The Naval Research Laboratory and the National Radio Astronomy Observatory completed implementation of a low frequency capability on the VLA at 73.8 MHz in 1998. This frequency band offers unprecedented sensitivity (~25 mJy/beam) and resolution (~25 arcsec) for low-frequency observations. We review the hardware, the calibration and imaging strategies, comparing them to those at higher frequencies, including aspects of interference excision and wide-field imaging. Ionospheric phase fluctuations pose the major difficulty in calibrating the array. Over restricted fields of view or at times of extremely quiescent ionospheric ``weather'', an angle-invariant calibration strategy can be used. In this approach a single phase correction is devised for each antenna, typically via self-calibration. Over larger fields of view or at times of more normal ionospheric ``weather'' when the ionospheric isoplanatic patch size is smaller than the field of view, we adopt a field-based strategy in which the phase correction depends upon location within the field of view. This second calibration strategy was implemented by modeling the ionosphere above the array using Zernike polynomials. Images of 3C sources of moderate strength are provided as examples of routine, angle-invariant calibration and imaging. Flux density measurements indicate that the 74 MHz flux scale at the VLA is stable to a few percent, and tied to the Baars et al. value of Cygnus A at the 5 percent level. We also present an example of a wide-field image, devoid of bright objects and containing hundreds of weaker sources, constructed from the field-based calibration. We close with a summary of lessons the 74 MHz system offers as a model for new and developing low-frequency telescopes. (Abridged)Comment: 73 pages, 46 jpeg figures, to appear in ApJ
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