2,776 research outputs found
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
Modified confidence intervals for the Mahalanobis distance
Reiser (2001) proposes a method of forming confidence interval for a Mahalanobis distance that yields intervals which have exactly the nominal coverage, but sometimes the interval is View the MathML source (0,0). We consider the case where Mahalanobis distance quantifies the difference between an individual and a population mean, and suggest a modification that avoids implausible intervals
Universal trapping scaling on the unstable manifold for a collisionless electrostatic mode
An amplitude equation for an unstable mode in a collisionless plasma is
derived from the dynamics on the two-dimensional unstable manifold of the
equilibrium. The mode amplitude decouples from the phase due to the
spatial homogeneity of the equilibrium, and the resulting one-dimensional
dynamics is analyzed using an expansion in . As the linear growth rate
vanishes, the expansion coefficients diverge; a rescaling
of the mode amplitude absorbs these
singularities and reveals that the mode electric field exhibits trapping
scaling as . The dynamics for
depends only on the phase where is the derivative of the dielectric as
.Comment: 11 pages (Latex/RevTex), 2 figures available in hard copy from the
Author ([email protected]); paper accepted by Physical Review
Letter
Nonlinear saturation of electrostatic waves: mobile ions modify trapping scaling
The amplitude equation for an unstable electrostatic wave in a multi-species
Vlasov plasma has been derived. The dynamics of the mode amplitude is
studied using an expansion in ; in particular, in the limit
, the singularities in the expansion coefficients are
analyzed to predict the asymptotic dependence of the electric field on the
linear growth rate . Generically , as
, but in the limit of infinite ion mass or for
instabilities in reflection-symmetric systems due to real eigenvalues the more
familiar trapping scaling is predicted.Comment: 13 pages (Latex/RevTex), 4 postscript encapsulated figures which are
included using the utility "uufiles". They should be automatically included
with the text when it is downloaded. Figures also available in hard copy from
the authors ([email protected]
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
Social behavior following traumatic brain injury and its association with emotion recognition, understanding of intentions, and cognitive flexibility
Although the adverse consequences of changes in social behavior following traumatic brain injury (TBI) are well documented, relatively little is known about possible underlying neuropsychological deficits. Following a model originally developed for social behavior deficits in schizophrenia, we investigated whether impairments in emotion recognition, understanding of other people's intentions ("theory of mind"), and cognitive flexibility soon after first TBI or 1 year later were associated with self and proxy ratings of behavior following TBI. Each of the three functions was assessed with two separate tests, and ratings of behavior were collected on three questionnaires. Patients with TBI (n = 33) were impaired in emotion recognition, "theory of mind," and cognitive flexibility compared with matched orthopedic controls (n = 34). Proxy ratings showed increases in behavioral problems 1 year following injury in the TBI group but not in the control group. However, test performance was not associated with questionnaire data. Severity of the impairments in emotion recognition, understanding intention, and flexibility were unrelated to the severity of behavioral problems following TBI. These findings failed to confirm the used model for social behavior deficits and may cast doubt on the alleged link between deficits in emotion recognition or theory of mind and social functioning
Antiretroviral Therapy-Associated Acute Motor and Sensory Axonal Neuropathy
Guillain-Barré syndrome (GBS) has been reported in HIV-infected patients in association with the immune reconstitution syndrome whose symptoms can be mimicked by highly active antiretroviral therapy (HAART)-mediated mitochondrial toxicity. We report a case of a 17-year-old, HIV-infected patient on HAART with a normal CD4 count and undetectable viral load, presenting with acute lower extremity weakness associated with lactatemia. Electromyography/nerve conduction studies revealed absent sensory potentials and decreased compound muscle action potentials, consistent with a diagnosis of acute motor and sensory axonal neuropathy. Lactatemia resolved following cessation of HAART; however, neurological deficits minimally improved over several months in spite of immune modulatory therapy. This case highlights the potential association between HAART, mitochondrial toxicity and acute axonal neuropathies in HIV-infected patients, distinct from the immune reconstitution syndrome
The Properties of Poor Groups of Galaxies: II. X-ray and Optical Comparisons
We use ROSAT PSPC data to study the X-ray properties of a sample of twelve
poor groups that have extensive membership information (Zabludoff and Mulchaey
1997; Paper I). Diffuse X-ray emission is detected in nine of these groups. In
all but one of the X-ray detected groups, the X-ray emission is centered on a
luminous elliptical galaxy. Fits to the surface brightness profiles of the
X-ray emission suggest the presence of two X-ray components in these groups.
The first component is centered on the central elliptical galaxy. The location
and extent of this component, combined with its X-ray temperature and
luminosity, favor an origin in the interstellar medium of the central galaxy.
Alternatively, the central component may be the result of a large-scale cooling
flow. The second X-ray component is detected out to a radius of at least
100-300 kpc. This component follows the same relationships found among the
X-ray temperature, X-ray luminosity and optical velocity dispersion of rich
clusters. This result suggests that the X-ray detected groups are low-mass
versions of clusters and that the extended gas component can properly be called
the intragroup medium, in analogy to the intracluster medium in clusters. We
also find a trend for the position angle of the optical light in the central
elliptical galaxy to align with the position angle of the large-scale X-ray
emission. (Abridged)Comment: 38 pages, AASLaTeX with 16 PS figures. Figure 1a-1l available in
gzipped postscript format at ftp://corvus.ociw.edu/pub/mulchae
The Norse waterways of West Mainland Orkney, Scotland
This study was funded by BA/Leverhulme Small Research Grants 2017-18 Round.Norse place-names for farms, individual landscape features and general landscape areas are ubiquitous throughout the Orkney Islands. These have an origin during the mediaeval period AD790–1350 when Orkney was ruled by Scandinavian earls. The oldest referenced maps for the parish of Harray (West Mainland, Orkney) suggests that in the past significant waterways crossed wetlands extending between the Loch of Harray and Houseby in an area associated with the earldom power base at Birsay. Subsequent drainage projects, changes in climate and sea level have since resulted in the loss of the waterways. An investigation of the wetlands using geophysical and geological analysis provided a reconstruction of the palaeo-environments. Comparison with place-names of significance allowed interpretation of possible routeways along navigable waters by shallow-draught Viking-Age vessels. The results allow for re-drawing the map of Norse Orkney and postulation of produce transfer corridors from estates in the south to the power centre at Birsay.PostprintPeer reviewe
NASA Sea Ice Validation Program for the Defense Meteorological Satellite Program Special Sensor Microwave Imager
The history of the program is described along with the SSM/I sensor, including its calibration and geolocation correction procedures used by NASA, SSM/I data flow, and the NASA program to distribute polar gridded SSM/I radiances and sea ice concentrations (SIC) on CD-ROMs. Following a discussion of the NASA algorithm used to convert SSM/I radiances to SICs, results of 95 SSM/I-MSS Landsat IC comparisons for regions in both the Arctic and the Antarctic are presented. The Landsat comparisons show that the overall algorithm accuracy under winter conditions is 7 pct. on average with 4 pct. negative bias. Next, high resolution active and passive microwave image mosaics from coordinated NASA and Navy aircraft underflights over regions of the Beaufort and Chukchi seas in March 1988 were used to show that the algorithm multiyear IC accuracy is 11 pct. on average with a positive bias of 12 pct. Ice edge crossings of the Bering Sea by the NASA DC-8 aircraft were used to show that the SSM/I 15 pct. ice concentration contour corresponds best to the location of the initial bands at the ice edge. Finally, a summary of results and recommendations for improving the SIC retrievals from spaceborne radiometers are provided
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