26,715 research outputs found
Precision voltage regulator
Balanced positive and negative voltage output circuit, in which error voltage for control is developed from difference in absolute value of positive and negative voltages referenced to a common point, regulates voltage for use with inertial reference unit. Fast-acting, temperature-compensated, high-gain operational amplifier circuits maintain common point
Alouette plasma resonance phenomena
Theoretical study of magnetoplasma resonance phenomena occurring perpendicular to magnetic fiel
POPULATION ECOLOGY OF THE NORTHERN SLIMY SALAMANDER (PLETHODON GLUTINOSUS) IN EAST-CENTRAL ILLINOIS
The importance of plethodontid salamanders in forested habitats has been recognized for decades and more recently plethodontids have been touted as a model taxon for monitoring ecosystem integrity and recovery. However, basic demographic data that are crucial to conservation and management plans are currently lacking for many species and regions. The objectives of our study were to characterize the population density, biomass, and capture success of a peripheral population of Plethodon glutinosus to provide a comparison for eastern populations and set a baseline for future monitoring of Midwestern populations. We estimated the population density of P. glutinosus at our site to be 0.41 salamanders/m2, with an estimated biomass of 0.70 g/m2. We did not find any evidence for temperature or precipitation affecting capture success. Our results showed that our density estimate falls within the range of other population ecology studies of Plethodon and sets a baseline for other peripheral Midwestern populations
Electronic integrator for gyro rate output voltages
Circuit which integrates spacecraft gyro output voltages to provide analog position signals has been developed. Accurate integration is provided by all solid state system which uses no choppers and takes advantage of commercially available flight qualified components
Ethnic parity in labour market outcomes for benefit claimants
A significant gap exists in the UK between the employment rate for Ethnic Minorities and that for
Whites. From a policy perspective, it is important to know whether this gap is due to differences in
the characteristics of White and Ethnic Minority groups (which reduce the employability of Ethnic
Minority groups relative to Whites) or whether it results from some form of discriminatory behaviour
in the labour market. In this paper, we use administrative data to estimate ethnic differences in
employment and benefit receipt amongst individuals who began claiming a Jobcentre Plus benefit
in 2003. In contrast to much of the previous UK literature, we use a number of different quantitative
techniques to estimate this gap, and show that in a lot of cases the estimates obtained are very
sensitive to the techniques used. We argue that for the questions we are interested in and the data
we have, propensity score matching methods are the most robust approach to estimating ethnic
parity. We compare this preferred approach with estimates derived using alternative approaches
commonly used in the literature (generally regression-based techniques) to determine the extent to
which more straightforward methods are able to replicate those produced by matching. In many
cases, it turns out not to be possible to calculate satisfactory quantitative estimates even with
matching techniques: the characteristics of Whites and Ethnic Minorities are simply too different
before the Jobcentre Plus intervention to reliably estimate the parameters of interest. Moreover, for
a number of the groups, results seem to be very sensitive to the methodology used. This calls into
question previous results based on simple regression techniques, which are likely to hide the fact
that observationally different ethnic groups are de facto being compared on the basis of parametric
extrapolations. Two groups for which it was possible to calculate reasonably reliable results are
incapacity benefit (IB) and income support (IS). For these groups we find that large and significant
raw penalties almost always disappear once we appropriately control for pre-inflow background
and labour market characteristics. There is also a good degree of consistency across
methodologies
A deep Chandra observation of the cluster environment of the z=1.786 radio galaxy 3C294
We report the results from a 200 ks Chandra observation of the z=1.786 radio
galaxy 3C294 and its cluster environment, increasing by tenfold our earlier
observation. The diffuse emission, extending about 100 kpc around the nucleus,
has a roughly hourglass shape in the N-S direction with surprisingly sharp
edges to the N and S. The spectrum of the diffuse emission is well fitted by
either a thermal model of temperature 3.5 keV and abundance <0.9 solar
(2-sigma), or a power-law with photon index 2.3. If the emission is due to hot
gas then the sharp edges mean that it is probably not in hydrostatic
equilibrium. Much of the emission is plausibly due to inverse Compton
scattering of the Cosmic Microwave Background (CMB) by nonthermal electrons
produced earlier by the radio source. The required relativistic electrons would
be of much lower energy and older than those responsible for the present radio
lobes. This could account for the lack of detailed spatial correspondence
between the X-rays and the radio emission, the axis of which is at a position
angle of about 45 deg. Hot gas would still be required to confine the
relativistic plasma; the situation could parallel that of the radio bubbles
seen as holes in nearby clusters, except that in 3C294 the bubbles are bright
in X-rays owing to the extreme power in the source and the sixty fold increase
in the energy density of the CMB. The X-ray spectrum of the radio nucleus is
hard, showing a reflection spectrum and iron line. The source is therefore an
obscured radio-loud quasar.Comment: In press (MNRAS), 10 pages, 12 figures (2 colour
Scaling and singularities in the entrainment of globally-coupled oscillators
The onset of collective behavior in a population of globally coupled
oscillators with randomly distributed frequencies is studied for phase
dynamical models with arbitrary coupling. The population is described by a
Fokker-Planck equation for the distribution of phases which includes the
diffusive effect of noise in the oscillator frequencies. The bifurcation from
the phase-incoherent state is analyzed using amplitude equations for the
unstable modes with particular attention to the dependence of the nonlinearly
saturated mode on the linear growth rate . In general
we find where is the
diffusion coefficient and is the mode number of the unstable mode. The
unusual factor arises from a singularity in the cubic term of
the amplitude equation.Comment: 11 pages (Revtex); paper submitted to Phys. Rev. Let
The Plasma Capacitor in a Magnetic Field
Impedance computations for parallel plate and coaxial cylinder plasma capacitors in magnetic fiel
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