1,683 research outputs found
Contextual effect on mortality of neighbourhood level education explained by earlier life deprivation
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
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 () 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 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
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
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
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
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
spectra in elementary cellular automata and fractal signals
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 spectra though considered as trivial, and on
the other hand that various automata classified as chaotic/complex display no
spectra. We model the results generalizing the recently investigated
Sierpinski signal to a class of fractal signals that are tailored to produce
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
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.
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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.
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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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