2,772 research outputs found
Boundary regularity for the Poisson equation in reifenberg-flat domains
This paper is devoted to the investigation of the boundary regularity for the
Poisson equation {{cc} -\Delta u = f & \text{in} \Omega u= 0 & \text{on}
\partial \Omega where belongs to some and is a
Reifenberg-flat domain of More precisely, we prove that given an
exponent , there exists an such that the
solution to the previous system is locally H\"older continuous provided
that is -Reifenberg-flat. The proof is based on
Alt-Caffarelli-Friedman's monotonicity formula and Morrey-Campanato theorem
“-itis & -itis”: Immune Checkpoint Inhibitors Toxicity Management
https://digitalcommons.psjhealth.org/other_pubs/1080/thumbnail.jp
Are spiral galaxies optically thin or thick?
The opacity of spiral galaxies is examined by modelling the dust and stellar
content of individual galaxies. The model is applied to five late-type spiral
galaxies (NGC 4013, IC 2531, UGC 1082, NGC 5529 and NGC 5907). Having analyzed
a total of seven galaxies thus far, the five galaxies mentioned above plus UGC
2048 and NGC 891 presented in (Xilouris et al. 1997, 1998), we are able to draw
some general conclusions, the most significant of which are: 1) The face-on
central optical depth is less than one in all optical bands indicating that
typical spiral galaxies like the ones that we have modelled would be completely
transparent if they were to be seen face-on. 2) The dust scaleheight is about
half that of the stars, which means that the dust is more concentrated near the
plane of the disk. 3) The dust scalelength is about 1.4 times larger than that
of the stars and the dust is more radially extended than the stars. 4) The dust
mass is found to be about an order of a magnitude more than previously measured
using the IRAS fluxes, indicating the existence of a cold dust component. The
gas-to-dust mass ratio calculated is close to the value derived for our Galaxy.
5) The derived extinction law matches quite well the Galactic extinction law,
indicating a universal dust behaviour.Comment: 13 pages. Accepted for publication in A&
Scaling laws for the photo-ionisation cross section of two-electron atoms
The cross sections for single-electron photo-ionisation in two-electron atoms
show fluctuations which decrease in amplitude when approaching the
double-ionisation threshold. Based on semiclassical closed orbit theory, we
show that the algebraic decay of the fluctuations can be characterised in terms
of a threshold law as with exponent
obtained as a combination of stability exponents of the triple-collision
singularity. It differs from Wannier's exponent dominating double ionisation
processes. The details of the fluctuations are linked to a set of infinitely
unstable classical orbits starting and ending in the non-regularisable triple
collision. The findings are compared with quantum calculations for a model
system, namely collinear helium.Comment: 4 pages, 1 figur
An Atlas of Monte Carlo Models of Dust Extinction in Galaxies for Cosmological Applications
We present an extensive study of the radiative transfer in dusty galaxies
based on Monte Carlo simulations. The main output of these simulations are the
attenuation curves (i.e. the ratio between the observed,
dust extinguished, total intensity to the intrinsic unextinguished one of the
galaxy as a function of wavelength). We have explored the dependence of on a conspicuous set of quantities (Hubble type, inclination, dust
optical thickness, dust distribution and extinction properties) for a large
wavelength interval, ranging from 1250\AA to the K band, thus finally providing
a comprehensive atlas of dust extinction in galaxies, which is electronically
available. This study is particularly suitable for inclusion into galaxy
formation evolution models and to directly interpret observational data on high
redshift galaxies.Comment: 29 pages, aasms4.sty, LaTeX, 5 figures. ApJSS, accepte
Psychometric properties of the Caregiver Preparedness Scale in caregivers of stroke survivors
Objective: To evaluate the psychometric characteristics of the Caregiver Preparedness Scale (CPS) in
caregivers of stroke survivors.
Background: Caregiver preparedness can have an important impact on both the caregiver and the stroke
survivor. The validity and reliability of the CPS has not been tested for the stroke-caregiver population.
Methods: We used a cross-sectional design to study a sample of 156 caregivers of stroke survivors.
Construct validity of the CPS was evaluated by confirmatory factor analysis (CFA). Internal consistency
and test-retest reliability were also evaluated.
Results: Caregivers were, on average, 54 year old (SD ¼ 13.2) and most were women (64.7%). CFA supported
the unidimensionality of the scale (comparative fit index ¼ 0.98). Reliability was also supported:
item-reliability index and itemetotal correlations above 0.30; composite reliability index ¼ 0.93;
Cronbach’s alpha ¼ 0.94; factor score determinacy ¼ 0.97; and test-retest reliability ¼ 0.92.
Conclusion: The CPS is valid and reliable in caregivers of stroke survivors. Scores on this scale may assist
health-care providers in identifying caregivers with less preparedness to provide specific interventions
Fracture Density Estimation Using Spectral Analysis of Reservoir Reflections: A Numerical Modeling Approach
We use a 3-D finite difference numerical model to generate synthetic seismograms from a simple fractured reservoir
containing evenly spaced, discrete, vertical fractures. The fractures are represented using a single column of
anisotropic grid points. Analysis of seismic amplitudes and spectral characteristics were carried out on the top and
base reservoir reflections as well as scattered wave coda for models with fracture spacing ranging from 0.01 to 0.1
fractures/m. Results show that the bulk scattered wave energy contained in a common shot gather increases greatly
when the fracture spacing is greater than about 1/4 wavelength. Wavenumber spectra for integrated amplitude
versus offset from a time window containing the base reservoir reflector show spectral peaks corresponding to the
fracture spacing.United States. Dept. of Energy (Grant DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources LaboratoryEni S.p.A. (Firm
A 60 pc counter-rotating core in NGC 4621
We present adaptive optics assisted OASIS integral field spectrography of the
S0 galaxy NGC 4621. Two-dimensional stellar kinematical maps (mean velocity and
dispersion) reveal the presence of a 60 pc diameter counter-rotating core
(CRC), the smallest observed to date. The OASIS data also suggests that the
kinematic center of the CRC is slightly offset from the center of the outer
isophotes. This seems to be confirmed by archival HST/STIS data. We also
present the HST/WFPC2 V-I colour map, which exhibits a central elongated red
structure, also slightly off-centered in the same direction as the kinematic
centre. We then construct an axisymmetric model of NGC 4621: the two-integral
distribution function is derived using the Multi-Gaussian Expansion and the
Hunter & Qian (1993) formalisms. Although the stellar velocities are reasonably
fitted, including the region of the counter-rotating core, significant
discrepancies between the model and the observations demonstrate the need for a
more general model (e.g. a three-integral model).Comment: 9 pages, 8 figure
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