59,745 research outputs found

    It’s driving her mad: gender differences in the effects of commuting on psychological well-being

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    In this paper, we seek to explore the effects of commuting time on the psychological well-being of men and women in the UK. We use annual data from the British Household Panel Survey in a fixed effects panel framework that includes variables known to determine well-being, as well as factors which may provide compensation for commuting such as income, job satisfaction and housing quality. Our results show that, even after all these variables are considered, commuting still has an important detrimental effect on the well-being of women, but not men, and this result is robust to numerous different specifications. We explore possible explanations for this gender difference and can find no evidence that it is due to women´s shorter working hours or weaker occupational position. Rather women´s greater sensitivity to commuting time seems to be a result of their larger responsibility for day-to-day household tasks, including childcare

    A new method to calibrate ionospheric pulse dispersion for UHE cosmic ray and neutrino detection using the Lunar Cherenkov technique

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    UHE particle detection using the lunar Cherenkov technique aims to detect nanosecond pulses of Cherenkov emission which are produced during UHE cosmic ray and neutrino interactions in the Moon's regolith. These pulses will reach Earth-based telescopes dispersed, and therefore reduced in amplitude, due to their propagation through the Earth's ionosphere. To maximise the received signal to noise ratio and subsequent chances of pulse detection, ionospheric dispersion must therefore be corrected, and since the high time resolution would require excessive data storage this correction must be made in real time. This requires an accurate knowledge of the dispersion characteristic which is parameterised by the instantaneous Total Electron Content (TEC) of the ionosphere. A new method to calibrate the dispersive effect of the ionosphere on lunar Cherenkov pulses has been developed for the LUNASKA lunar Cherenkov experiments. This method exploits radial symmetries in the distribution of the Moon's polarised emission to make Faraday rotation measurements in the visibility domain of synthesis array data (i. e. instantaneously). Faraday rotation measurements are then combined with geomagnetic field models to estimate the ionospheric TEC. This method of ionospheric calibration is particularly attractive for the lunar Cherenkov technique as it may be used in real time to estimate the ionospheric TEC along a line-of-sight to the Moon and using the same radio telescope.Comment: 4 pages, 2 figures, Proceedings of ARENA 2010, Nantes, France; doi:10.1016/j.nima.2010.10.12

    Stark ladders as tunable far-infrared emitters

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    A superlattice of GaAs/Ga(1 – x)Al(x)As quantum wells forms a Stark ladder under the influence of a perpendicular electric field. A two level incoherent emitter system, formed by radiative intersubband transitions between adjacent wells, is investigated as a tunable far-infrared radiation source. Intersubband transition rates are calculated at 4, 77, and 300 K for applied fields from 0 to 40 kV cm(–1). It is shown that the quantum efficiency of the radiative emission reaches a maximum at low temperatures for a field of 32 kV cm(–1). Under these conditions the emission wavelength is 38 µm with an estimated power output of 1.1 mW. © 1998 American Institute of Physics

    Wide range operation of advanced low NOx combustors for supersonic high-altitude aircraft gas turbines

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    An initial rig program tested the Jet Induced Circulation (JIC) and Vortex Air Blast (VAB) systems in small can combustor configurations for NOx emissions at a simulated high altitude, supersonic cruise condition. The VAB combustor demonstrated the capability of meeting the NOx goal of 1.0 g NO2/kg fuel at the cruise condition. In addition, the program served to demonstrate the limited low-emissions range available from the lean, premixed combustor. A follow-on effort was concerned with the problem of operating these lean, premixed combustors with acceptable emissions at simulated engine idle conditions. Various techniques have been demonstrated that allow satisfactory operation on both the JIC and VAB combustors at idle with CO emissions below 20 g/kg fuel. The VAB combustor was limited by flashback/autoignition phenomena at the cruise conditions to a pressure of 8 atmospheres. The JIC combustor was operated up to the full design cruise pressure of 14 atmospheres without encountering an autoignition limitation although the NOx levels, in the 2-3 g NO2/kg fuel range, exceeded the program goal

    To punish first and reward second: Values determine how reward and punishment affect risk-taking behavior

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    The current study investigated whether manipulating participants’ pre-exposure to reward and punishment affects the extent to which sensation seeking and values predict risk-taking behavior. Participants (n = 195) were randomly allocated to one of two conditions, defined by the order at which they were rewarded or punished for risk-taking behavior. Risk-taking behavior was measured in both conditions using the Balloon Analogue Risk Test, however this was set-up such that participants in group 1 were rewarded for risk-taking behavior prior to being punished, whereas participants in group 2 were punished for risk-taking behavior prior to being rewarded. Participants also completed questionnaires designed to measure sensation seeking and the values of ‘stimulation’ (the need for novelty and excitement) and ‘hedonism’ (the need for sensuous pleasure). It was found that stimulation predicted risk taking behavior in the ‘reward-then-punishment’ condition, whereas hedonism predicted risk-taking behavior in the ‘punishment-then-reward’ condition. Sensation-seeking was found to be an indirect predictor of risk-taking behavior in both conditions. It is tentatively concluded that the extent to which an individual’s risk-taking behavior is guided by their values (hedonism, stimulation) largely depends on their prior exposure to the order of contingent reward and punishment

    Three-dimensionality in quasi-two dimensional flows: recirculations and barrel effects

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    A scenario is put forward for the appearance of three-dimensionality both in quasi-2D rotating flows and quasi-2D magnetohydrodynamic (MHD) flows. We show that 3D recirculating flows and currents originate in wall boundary layers and that, unlike in ordinary hydrodynamic flows, they cannot be ignited by confinement alone. They also induce a second form of three-dimensionality with quadratic variations of velocities and current across the channel. This scenario explains both the common tendency of these flows to two-dimensionality and the mechanisms of the recirculations through a single formal analogy covering a wide class of flow including rotating and MHD flows. These trans-disciplinary effects are thus active in atmospheres, oceans or the cooling blankets of nuclear fusion reactors.Comment: 6 pages, 1 Figur

    Mock Catalogs for UHECR Studies

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    We provide realistic mock-catalogs of cosmic rays above 40 EeV, for a pure proton composition, assuming their sources are a random subset of ordinary galaxies in a simulated, volume-limited survey, for various choices of source density: 10^-3.5 Mpc^-3, 10^-4.0 Mpc^-3 and 10^-4.5 Mpc^-3. The spectrum at the source is taken to be E^-2.3 and the effects of cosmological redshifting as well as photo-pion and e^+ e^- energy losses are included.Comment: 7 pages, 4 figure

    Stochastic Resonance in a simple model of magnetic reversals

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    We discuss the effect of stochastic resonance in a simple model of magnetic reversals. The model exhibits statistically stationary solutions and bimodal distribution of the large scale magnetic field. We observe a non trivial amplification of stochastic resonance induced by turbulent fluctuations, i.e. the amplitude of the external periodic perturbation needed for stochastic resonance to occur is much smaller than the one estimated by the equilibrium probability distribution of the unperturbed system. We argue that similar amplifications can be observed in many physical systems where turbulent fluctuations are needed to maintain large scale equilibria.Comment: 6 page

    Ride quality sensitivity to SAS control law and to handling quality variations

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    The RQ trends which large flexible aircraft exhibit under various parameterizations of control laws and handling qualities are discussed. A summary of the assumptions and solution technique, a control law parameterization review, a discussion of ride sensitivity to handling qualities, and the RQ effects generated by implementing relaxed static stability configurations are included

    Advanced Low NO Sub X Combustors for Supersonic High-Altitude Aircraft Gas Turbines

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    A test rig program was conducted with the objective of evaluating and minimizing the exhaust emissions, in particular NO sub x, of three advanced aircraft combustor concepts at a simulated, high altitude cruise condition. The three combustor designs, all members of the lean reaction, premixed family, are the Jet Induced Circulation (JIC) combustor, the Vortex Air Blast (VAB) combustor, and a catalytic combustor. They were rig tested in the form of reverse flow can combustors in the 0.127 m. (5.0 in.) size range. Various configuration modifications were applied to each of the initial JIC and VAB combustor model designs in an effort to reduce the emissions levels. The VAB combustor demonstrated a NO sub x level of 1.1 gm NO2/kg fuel with essentially 100% combustion efficiency at the simulated cruise combustor condition of 50.7 N/sq cm (5 atm), 833 K (1500 R) inlet pressure and temperature respectively and 1778 K (3200 R) outlet temperature on Jet-A1 fuel. Early tests on the catalytic combustor were unsuccessful due to a catalyst deposition problem and were discontinued in favor of the JIC and VAB tests. In addition emissions data were obtained on the JIC and VAB combustors at low combustor inlet pressure and temperatures that indicate the potential performance at engine off-design conditions
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