5,270 research outputs found

    The ortho-para H2 distribution on Uranus: Constraints from the collision-induced 3-0 dipole band and 4-0 S(0) and S(1) quadrupole line profiles

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    Recent high quality spectral observations have allowed the derivation of constraints on the atmospheric structure of Uranus. The present analysis, which is based on the detailed modeling of a broadband geometric albedo spectrum and high resolution observations of the H2 4-0 quadrupole and 6818.9-A CH4 features, yields (1) a family of models which parameterize an upper tropospheric haze layer, (2) a lower, optically infinite cloud at a given pressure level, (3) the cloud-level methane molar fraction, and (4) the mean ortho/para ratio in the visible atmosphere. The single scattering albedo of atmospheric aerosols exhibits a steep darkening between 5890 and 6040 A

    'White knuckle care work' : violence, gender and new public management in the voluntary sector

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    Drawing on comparative data from Canada and Scotland, this article explores reasons why violence is tolerated in non-profit care settings. This article will provide insights into how workers' orientations to work, the desire to care and the intrinsic rewards from working in a non-profit context interact with the organization of work and managerially constructed workplace norms and cultures (Burawoy, 1979) to offset the tensions in an environment characterized by scarce resources and poor working conditions. This article will also outline how the same environment of scarce resources causes strains in management's efforts to establish such cultures. Working with highly excluded service users with problems that do not respond to easy interventions, workers find themselves working at the edge of their endurance, hanging on by their fingernails, and beginning to participate in various forms of resistance; suggesting that even among the most highly committed, 'white knuckle care' may be unsustainable

    Nodeless superconductivity in the noncentrosymmetric Mo3_3Rh2_2N superconductor: a μ\muSR study

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    The noncentrosymmetric superconductor Mo3_3Rh2_2N, with Tc=4.6T_c = 4.6 K, adopts a β\beta-Mn-type structure (space group PP41_132), similar to that of Mo3_3Al2_2C. Its bulk superconductivity was characterized by magnetization and heat-capacity measurements, while its microscopic electronic properties were investigated by means of muon-spin rotation and relaxation (μ\muSR). The low-temperature superfluid density, measured via transverse-field (TF)-μ\muSR, evidences a fully-gapped superconducting state with Δ0=1.73kBTc\Delta_0 = 1.73 k_\mathrm{B}T_c, very close to 1.76 kBTck_\mathrm{B}T_c - the BCS gap value for the weak coupling case, and a magnetic penetration depth λ0=586\lambda_0 = 586 nm. The absence of spontaneous magnetic fields below the onset of superconductivity, as determined by zero-field (ZF)-μ\muSR measurements, hints at a preserved time-reversal symmetry in the superconducting state. Both TF-and ZF-μ\muSR results evidence a spin-singlet pairing in Mo3_3Rh2_2N.Comment: 5 figures and 5 pages. Accepted for publication as a Rapid Communication in Phys. Rev.

    Constrained by managerialism : caring as participation in the voluntary social services

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    The data in this study show that care is a connective process, underlying and motivating participation and as a force that compels involvement in the lives of others, care is at least a micro-participative process. Care or affinity not only persisted in the face of opposition, but it was also used by workers as a counter discourse and set of practices with which to resist the erosion of worker participation and open up less autonomized practices and ways of connecting with fellow staff, clients and the communities they served. The data suggest that while managerialism and taylorised practice models may remove or reduce opportunities for worker participation, care is a theme or storyline that gave workers other ways to understand their work and why they did it, as well as ways they were prepared to resist managerial priorities and directives, including the erosion of various kinds of direct and indirect participation. The degree of resistance possible, even in the highly technocratic worksite in Australia, shows that cracks and fissures exist within managerialism

    Magnetic order in the quasi-one-dimensional spin 1/2 chain, copper pyrazine dinitrate

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    We present the first evidence of magnetic order in the quasi-one-dimensional spin 1/2 molecular chain compound, copper pyrazine dinitrate Cu(C4H4N2)(NO3)2}. Zero field muon-spin relaxation measurements made at dilution refrigerator temperatures show oscillations in the measured asymmetry, characteristic of a quasistatic magnetic field at the muon sites. Our measurements provide convincing evidence for long range magnetic order below a temperature T_N=107(1) mK. This leads to an estimate of the interchain coupling constant of |J'|/k_B=0.046 K and to a ratio |J'/J| = 4.4 x 10^-3.Comment: 4 pages, 3 figures. Submitted to Physical Review Letter

    The Ages of A-Stars I: Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group

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    We have observed and spatially resolved a set of seven A-type stars in the nearby Ursa Major moving group with the Classic, CLIMB, and PAVO beam combiners on the CHARA Array. At least four of these stars have large rotational velocities (vsiniv \sin i \gtrsim 170 km s1\mathrm{km~s^{-1}}) and are expected to be oblate. These interferometric measurements, the stars' observed photometric energy distributions, and vsiniv \sin i values are used to computationally construct model oblate stars from which stellar properties (inclination, rotational velocity, and the radius and effective temperature as a function of latitude, etc.) are determined. The results are compared with MESA stellar evolution models (Paxton et al. 2011, 2013) to determine masses and ages. The value of this new technique is that it enables the estimation of the fundamental properties of rapidly rotating stars without the need to fully image the star. It can thus be applied to stars with sizes comparable to the interferometric resolution limit as opposed to those that are several times larger than the limit. Under the assumption of coevality, the spread in ages can be used as a test of both the prescription presented here and the MESA evolutionary code for rapidly rotating stars. With our validated technique, we combine these age estimates and determine the age of the moving group to be 414 ±\pm 23 Myr, which is consistent with, but much more precise than previous estimates.Comment: Accepted by Ap

    Ruling Out Possible Secondary Stars to Exoplanet Host Stars Using the CHARA Array

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    Of the over 450 exoplanets known to date, more than 420 of them have been discovered using radial velocity studies, a method that tells nothing about the inclination of the planet's orbit. Because it is more likely that the companion is a planetary-mass object in a moderate- to high-inclination orbit than a low-mass stellar object in a nearly face-on orbit, the secondary bodies are presumed to be planets. Interferometric observations allow us to inspect the angular diameter fit residuals to calibrated visibilities in order to rule out the possibility of a low-mass stellar companion in a very low-inclination orbit. We used the Center for High Angular Resolution Astronomy (CHARA) Array interferometer to observe 20 exoplanet host stars and considered five potential secondary spectral types: G5 V, K0 V, K5 V, M0 V, and M5 V. If a secondary star is present and is sufficiently bright, the effects of the added light will appear in interferometric observations where the planet will not. All secondary types could be eliminated from consideration for 7 host stars and no secondary stars of any spectral type could be ruled out for 7 more. The remaining 6 host stars showed a range of possible secondary types.Comment: Accepted for publication in the Astronomical Journa

    Radial Velocities of Six OB Stars

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    We present new results from a radial velocity study of six bright OB stars with little or no prior measurements. One of these, HD 45314, may be a long-period binary, but the velocity variations of this Be star may be related to changes in its circumstellar disk. Significant velocity variations were also found for HD 60848 (possibly related to nonradial pulsations) and HD 61827 (related to wind variations). The other three targets, HD 46150, HD 54879, and HD 206183, are constant velocity objects, but we note that HD 54879 has Hα\alpha emission that may originate from a binary companion. We illustrate the average red spectrum of each target.Comment: Accepted for publication in PASP July 2007 issu
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