3,810 research outputs found

    Introduction: Exploring feminist ecological economics

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    These Explorations argue that more links between the fields of feminist ecology and feminist economics are both needed and promising, and presents new, boundary-crossing research in this area. It brings together contributions from various regions in the world that link political action and experience in practice and research in an economic theorizing that includes both environmental and feminist concerns.This research was supported by the Social Sciences and Humanities Research Council of Canad

    WP 32 - Tax evasive behaviour and gender in a transition country

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    In this paper, we provide a structural explanation of gender difference with respect to tax evasion. A unique data set, collected from a field survey of households in Albania, allows us to test and explore the established fact, in a transition country. The results show that women tend to evade taxes less than men, even after controlling for socio-economic and demographic characteristics (e.g., age, family status, education, income). Starting from neo-institutional theory, the paper analyzes the explanatory power of this theory where it concerns the differences in men’s and women’s tax behavior. Acknowledging the fact that gender differences in economic behavior are generally explained either as biological or by social/psychological role theory, this paper also discusses possible explanations as suggested in feminist economic research. Using the data available, some main hypothesis are articulated, tested and evaluated.

    A search for 183-GHz emission from water in late-type stars

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    A search was made for 183 GHz line emission from water vapor in the direction of twelve Mira and two semiregular variables. Upper limits to the emission are in the range of 2000 to 5000 Jy. It is estimated that thermal emission from the inner regions of late type stellar envelopes will be on the order of ten Jy. Maser emission, according to one model, would be an order of magnitude stronger. From the limited set sampled, the possibility of very strong maser emission at 183 GHz cannot yet be ruled out

    183 GHz water line variation: An energetic outburst in orion KL

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    Observations of the 3(13)-2(20) transition of water vapor in the direction of Ori MC1 in 1980 February show a 50% flux increase and an apparent additional red shift of approximately 2 km/s relative to the line observed in 1977 December. From a detailed examination of the amplitude and frequency calibration, it appears unlikely that the effect is due to systematic error. The increase is attributed to the appearance of a new component at a velocity of 12 km/s with respect to the local standard of rest. The new component also has broad wings. Increased emission from a region in the high-velocity core of Ori MC1 can be due either to additional far-IR radiation to pump the 1983 GHz transition or to a change in the physical conditions in the gas. Statistical equilibrium calculations using the large-velocity-gradient formalism were carried out to develop a model for the emission. The calculations support a model in which the gas in the region of enhanced emission is hotter than the dust. The temporal coincidence between the 183 GHZ increase and the 22 GH1 water maser outburst suggests a common, impulsive cause, which has heated the gas in a part of the HV source, enhancing the emission in both transitions

    A general hybrid radiation transport scheme for star formation simulations on an adaptive grid

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    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodynamics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion (FLD) solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calculating gas and dust temperatures in the presence of multiple stellar sources. Our method enables radiation-hydrodynamic studies of young stellar objects, protostellar disks, and clustered star formation in magnetized, filamentary environments.Comment: 16 pages, 15 figures, accepted to Ap

    The transitional millisecond pulsar IGR J18245-2452 during its 2013 outburst at X-rays and soft gamma-rays

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    IGR~J18245--2452/PSR J1824--2452I is one of the rare transitional accreting millisecond X-ray pulsars, showing direct evidence of switches between states of rotation powered radio pulsations and accretion powered X-ray pulsations, dubbed transitional pulsars. IGR~J18245--2452 is the only transitional pulsar so far to have shown a full accretion episode, reaching an X-ray luminosity of ∌1037\sim10^{37}~erg~s−1^{-1} permitting its discovery with INTEGRAL in 2013. In this paper, we report on a detailed analysis of the data collected with the IBIS/ISGRI and the two JEM-X monitors on-board INTEGRAL at the time of the 2013 outburst. We make use of some complementary data obtained with the instruments on-board XMM-Newton and Swift in order to perform the averaged broad-band spectral analysis of the source in the energy range 0.4 -- 250~keV. We have found that this spectrum is the hardest among the accreting millisecond X-ray pulsars. We improved the ephemeris, now valid across its full outburst, and report the detection of pulsed emission up to ∌60\sim60 keV in both the ISGRI (10.9σ10.9 \sigma) and Fermi/GBM (5.9σ5.9 \sigma) bandpass. The alignment of the ISGRI and Fermi GBM 20 -- 60 keV pulse profiles are consistent at a $\sim25\ \mu$s level. We compared the pulse profiles obtained at soft X-rays with \xmm\ with the soft \gr-ray ones, and derived the pulsed fractions of the fundamental and first harmonic, as well as the time lag of the fundamental harmonic, up to 150 Ό150\ \mus, as a function of energy. We report on a thermonuclear X-ray burst detected with \Integ, and using the properties of the previously type-I X-ray burst, we show that all these events are powered primarily by helium ignited at a depth of yign≈2.7×108y_{\rm ign} \approx 2.7\times10^8 g cm−2{}^{-2}. For such a helium burst the estimated recurrence time of Δtrec≈5.6\Delta t_{\rm rec}\approx5.6 d is in agreement with the observations.Comment: 10 pages, 6 Figures, 3 Tables Astronomy and Astrophysics Journal, accepted for publication on the 13th of April 201

    Accreting millisecond X-ray pulsars: 10 years of INTEGRAL observations

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    During the last 10 years, INTEGRAL made a unique contribution to the study of accreting millisecond X-ray pulsars (AMXPs), discovering three of the 14 sources now known of this class. Besides increasing the number of known AMXPs, INTEGRAL also carried out observations of these objects above 20 keV, substantially advancing our understanding of their behaviour. We present here a review of all the AMXPs observed with INTEGRAL and discuss the physical interpretation of their behaviour in the X-ray domain. We focus in particular on the lightcurve profile during outburst, as well as the timing, spectral, and thermonuclear type-I X-ray bursts properties.Comment: 8 pages, 8 figures. Proceedings of "An INTEGRAL view of the high-energy sky (the first 10 years)" the 9th INTEGRAL Workshop, October 15-19, 2012, Paris, Franc

    INTEGRAL and RXTE observations of accreting millisecond pulsar IGR J00291+5934 in outburst

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    Simultaneous observations of the accretion-powered millisecond pulsar IGR J00291+5934 by International Gamma-Ray Astrophysics Laboratory and Rossi X-ray Timing Explorer during the 2004 December outburst are analysed. The average spectrum is well described by thermal Comptonization with an electron temperature of 50 keV and Thomson optical depth tau_T ~ 1 in a slab geometry. The spectral shape is almost constant during the outburst. We detect a spin-up of the pulsar with nudot=8.4x10E-13 Hz/s. The ISGRI data reveal the pulsation of X-rays at a period of 1.67 milliseconds up to ~150 keV. The pulsed fraction is shown to increase from 6 per cent at 6 keV to 12--20 per cent at 100 keV. This is naturally explained by the action of the Doppler effect the exponentially cutoff Comptonization spectrum from the hot spot. The nearly sinusoidal pulses show soft lags with complex energy dependence, increasing up to 7 keV, then decreasing to 15 keV, and seemingly saturating at higher energies.Comment: 11 pages, 8 figures, 3 tables, accepted for publication on A&

    Difference of optical conductivity between one- and two-dimensional doped nickelates

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    We study the optical conductivity in doped nickelates, and find the dramatic difference of the spectrum in the gap (ω\omega\alt4 eV) between one- (1D) and two-dimensional (2D) nickelates. The difference is shown to be caused by the dependence of hopping integral on dimensionality. The theoretical results explain consistently the experimental data in 1D and 2D nickelates, Y2−x_{2-x}Cax_xBaNiO5_5 and La2−x_{2-x}Srx_xNiO4_4, respectively. The relation between the spectrum in the X-ray aborption experiments and the optical conductivity in La2−x_{2-x}Srx_xNiO4_4 is discussed.Comment: RevTeX, 4 pages, 4 figure
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