1,683 research outputs found

    Contextual effect on mortality of neighbourhood level education explained by earlier life deprivation

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    Various aspects of socioeconomic conditions in the neighbourhood have in recent years been found to have an influence on morbidity and mortality even after individual characteristics are taken into account.1 Increasing evidence suggests that to measure fully the impact social conditions may have on mortality risk, the whole life course must be taken into account as mortality risk increases cumulatively over the life course.2 Few studies have combined ecological and life course factors to see if contextual effects may be explained by social conditions earlier in life at the individual level.3,4 Most studies of neighbourhood effects have had a cross sectional design or with short follow up. Effects seen could be a consequence of the fact that people in these areas may have different earlier life experiences that have not been fully taken into account. In this study we examine whether the contextual effect of educational level aggregated to the neighbourhood on mortality risk could be explained by earlier life deprivation

    Estimation of time delay by coherence analysis

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    Using coherence analysis (which is an extensively used method to study the correlations in frequency domain, between two simultaneously measured signals) we estimate the time delay between two signals. This method is suitable for time delay estimation of narrow band coherence signals for which the conventional methods cannot be reliably applied. We show by analysing coupled R\"ossler attractors with a known delay, that the method yields satisfactory results. Then, we apply this method to human pathologic tremor. The delay between simultaneously measured traces of Electroencephalogram (EEG) and Electromyogram (EMG) data of subjects with essential hand tremor is calculated. We find that there is a delay of 11-27 milli-seconds (msms) between the tremor correlated parts (cortex) of the brain (EEG) and the trembling hand (EMG) which is in agreement with the experimentally observed delay value of 15 msms for the cortico-muscular conduction time. By surrogate analysis we calculate error-bars of the estimated delay.Comment: 21 pages, 8 figures, elstart.cls file included. Accepted for publication in Physica

    The association between water kilomasers and compact radio sources in the starburst galaxy NGC2146

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    We report the detection of 22 GHz water vapor emission toward the starburst galaxy NGC2146, made using the Effelsberg 100-m telescope. Interferometric observations with the Very Large Array (VLA) show that a part of the emission originates from two prominent sites of star formation that are associated with compact radio continuum sources, likely ultra-compact HII regions. It is concluded that the emission arises from the most luminous and distant water `kilomasers' detected so far. Our data increase the number of water maser detections in northern galaxies (Dec > -30 deg) with 100 micron IRAS point source fluxes > 50 Jy to 18%.Comment: 4 pages including 3 figures, accepted for publication in A&A Lette

    The Sizes of 1720 MHz OH Masers: VLBA and MERLIN Observations of the Supernova Remnants W44 and W28

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    We have used the NRAO Very Long Baseline Array (VLBA) to image OH(1720 MHz) masers in the supernova remnants W28 and W44 at a resolution of 40 mas. We also used MERLIN to observe the same OH(1720 MHz) masers in W44 at a resolution of 290 x 165 mas. All the masers are resolved by these VLBA and MERLIN observations. The measured sizes range from 50 to 180 mas and yield brightness temperature estimates from 0.3--20 x 10**8 K. We investigate whether these measured angular sizes are intrinsic and hence originate as a result of the physical conditions in the supernova remnant shock, or whether they are scatter broadened sizes produced by the turbulent ionized gas along the line of sight. While the current data on the temporal and angular broadening of pulsars, masers and extragalactic soures toward W44 and W28 can be understood in terms of scattering, we cannot rule out that these large sizes are intrinsic. Recent theoretical modeling by Lockett et al. suggests that the physical parameters in the shocked region are indicative of densities and OH abundances which lead to estimates of sizes as large as what we measure. If the sizes and structure are intrinsic, then the OH(1720 MHz) masrs may be more like the OH(1612 MHz) masers in circumstellar shells than OH masers associated with HII regions. At two locations in W28 we observe the classical S-shapes in the Stokes V profiles caused by Zeeman splitting and use it to infer magnetic fields of order 2 milliGauss.Comment: 24 pages, 6 figures, accepted by Ap

    A Proper Motion Study of the Haro 6-10 Outflow: Evidence for a Subarcsecond Binary

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    We present single-dish and VLBI observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1.3" north. Using the Very Long Baseline Array, we obtained five observations spanning 3 months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over 3 or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow that lies nearly in the plane of the sky with an opening angle of ~45\deg. They are located within 50 mas of the southern component of the binary, the visible T Tauri star Haro 6-10S. The mean position angle on the sky of the maser proper motions (~220\deg) suggests they are related to the previously observed giant Herbig-Haro (HH) flow which includes HH410, HH411, HH412, and HH184A-E. A previously observed HH jet and extended radio continuum emission (mean position angle of ~190\deg) must also originate in the vicinity of Haro6-10S and represent a second, distinct outflow in this region. We propose that a yet unobserved companion within 150 mas of Haro6-10S is responsible for the giant HH/maser outflow while the visible star is associated with the HH jet. Despite the presence of H_2 emission in the spectrum of the northern component of the binary, Haro6-10N, none of outflows/jets can be tied directly to this young stellar object

    Majority voting leads to unanimity

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    We consider a situation where society decides, through majority voting in a secret ballot, between the alternatives of ‘reform’ and ‘status quo’. Reform is assumed to create a minority of winners, while being efficient in the Kaldor-Hicks sense. We explore the consequences of allowing binding transfers between voters conditional on the chosen alternative. In particular, we establish conditions under which the winners wish to compensate all losers, thus leading to unanimity for reform, rather than compensating some losers to form a non-maximal majority. The analysis employs concepts from cooperative game theory

    1/fα1/f^\alpha spectra in elementary cellular automata and fractal signals

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    We systematically compute the power spectra of the one-dimensional elementary cellular automata introduced by Wolfram. On the one hand our analysis reveals that one automaton displays 1/f1/f spectra though considered as trivial, and on the other hand that various automata classified as chaotic/complex display no 1/f1/f spectra. We model the results generalizing the recently investigated Sierpinski signal to a class of fractal signals that are tailored to produce 1/fα1/f^{\alpha} spectra. From the widespread occurrence of (elementary) cellular automata patterns in chemistry, physics and computer sciences, there are various candidates to show spectra similar to our results.Comment: 4 pages (3 figs included

    Using geographic information systems for radon exposure assessment in dwellings in the Oslo region, Norway

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    Radon exposures were assigned to each residential address in the Oslo region using a geographic information system (GIS) that included indoor radon measurements. The results will be used in an epidemiologic study regarding leukemia and brain cancer. The model is based on 6% of measured residential buildings. High density of indoor radon measurements allowed us to develop a buffer model where indoor radon measurements found around each dwelling were used to assign a radon value for homes lacking radon measurement. <br><br> Intraclass correlation coefficients (ICCs) were used to study the agreement between radon values from the buffer method, from indoor radon values of measured houses, and from a regression model constructed with radiometric data (<i>e</i><sub>Th</sub>, <i>e</i><sub>U</sub>) and bedrock geology. We obtained good agreement for both comparisons with ICC values between 0.54 and 0.68. <br><br> GIS offers a useful variety of tools to study the indoor-radon exposure assessment. By using the buffer method it is more likely that geological conditions are similar within the buffer and this may take more into account the variation of radon over short distances. It is also probable that short-distance-scale correlation patterns express similarities in building styles and living habits. Although the method has certain limitations, we regard it as acceptable for use in epidemiological studies
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