51 research outputs found
Challenges and Inconsistencies Facing the Posthumously Conceived Child
This Note will discuss the problems with the Supreme Court of the United States’ decision, the inconsistencies that exist in state intestacy law, and the solutions that are necessary to remedy these challenges. Part II gives a brief background of the facts and circumstances surrounding Astrue. Part III discusses the history of the Social Security Administration and in vitro fertilization and points out the conflicting results from various jurisdictions that have death with this issue. Part IV delves into the Supreme Court\u27s reasoning behind its decision in Astrue. Finally, Part V comments on the reasons Astrue was poorly decided, the difficulties that will result from the decision, and the methods to resolve these complications
Challenges and Inconsistencies Facing the Posthumously Conceived Child
This Note will discuss the problems with the Supreme Court of the United States’ decision, the inconsistencies that exist in state intestacy law, and the solutions that are necessary to remedy these challenges. Part II gives a brief background of the facts and circumstances surrounding Astrue. Part III discusses the history of the Social Security Administration and in vitro fertilization and points out the conflicting results from various jurisdictions that have death with this issue. Part IV delves into the Supreme Court\u27s reasoning behind its decision in Astrue. Finally, Part V comments on the reasons Astrue was poorly decided, the difficulties that will result from the decision, and the methods to resolve these complications
Curvaton reheating: an application to braneworld inflation
The curvaton was introduced recently as a distinct inflationary mechanism for
generating adiabatic density perturbations. Implicit in that scenario is that
the curvaton offers a new mechanism for reheating after inflation, as it is a
form of energy density not diluted by the inflationary expansion. We consider
curvaton reheating in the context of a braneworld inflation model, {\em steep
inflation}, which features a novel use of the braneworld to give a new
mechanism for ending inflation. The original steep inflation model featured
reheating by gravitational particle production, but the inefficiency of that
process brings observational difficulties. We demonstrate here that the
phenomenology of steep inflation is much improved by curvaton reheating.Comment: 8 pages RevTeX4 file with two figures incorporated. Improved
referencing, matches PRD accepted versio
Accelerated expansion from braneworld models with variable vacuum energy
In braneworld models a variable vacuum energy may appear if the size of the
extra dimension changes during the evolution of the universe. In this scenario
the acceleration of the universe is related not only to the variation of the
cosmological term, but also to the time evolution of and, possibly, to the
variation of other fundamental "constants" as well. This is because the
expansion rate of the extra dimension appears in different contexts, notably in
expressions concerning the variation of rest mass and electric charge. We
concentrate our attention on spatially-flat, homogeneous and isotropic,
brane-universes where the matter density decreases as an inverse power of the
scale factor, similar (but at different rate) to the power law in FRW-universes
of general relativity.
We show that these braneworld cosmologies are consistent with the observed
accelerating universe and other observational requirements. In particular,
becomes constant and asymptotically in
time. Another important feature is that the models contain no "adjustable"
parameters. All the quantities, even the five-dimensional ones, can be
evaluated by means of measurements in 4D. We provide precise constrains on the
cosmological parameters and demonstrate that the "effective" equation of state
of the universe can, in principle, be determined by measurements of the
deceleration parameter alone. We give an explicit expression relating the
density parameters , and the deceleration
parameter . These results constitute concrete predictions that may help in
observations for an experimental/observational test of the model.Comment: References added, typos correcte
Respiratory syncytial virus infection activates IL-13–producing group 2 innate lymphoid cells through thymic stromal lymphopoietin
BACKGROUND:
Respiratory syncytial virus (RSV) is a major health care burden with a particularly high worldwide morbidity and mortality rate among infants. Data suggest that severe RSV-associated illness is in part caused by immunopathology associated with a robust type 2 response.
OBJECTIVE:
We sought to determine the capacity of RSV infection to stimulate group 2 innate lymphoid cells (ILC2s) and the associated mechanism in a murine model.
METHODS:
Wild-type (WT) BALB/c, thymic stromal lymphopoietin receptor (TSLPR) knockout (KO), or WT mice receiving an anti-TSLP neutralizing antibody were infected with the RSV strain 01/2-20. During the first 4 to 6 days of infection, lungs were collected for evaluation of viral load, protein concentration, airway mucus, airway reactivity, or ILC2 numbers. Results were confirmed with 2 additional RSV clinical isolates, 12/11-19 and 12/12-6, with known human pathogenic potential.
RESULTS:
RSV induced a 3-fold increase in the number of IL-13-producing ILC2s at day 4 after infection, with a concurrent increase in total lung IL-13 levels. Both thymic stromal lymphopoietin (TSLP) and IL-33 levels were increased 12 hours after infection. TSLPR KO mice did not mount an IL-13-producing ILC2 response to RSV infection. Additionally, neutralization of TSLP significantly attenuated the RSV-induced IL-13-producing ILC2 response. TSLPR KO mice displayed reduced lung IL-13 protein levels, decreased airway mucus and reactivity, attenuated weight loss, and similar viral loads as WT mice. Both 12/11-19 and 12/12-6 similarly induced IL-13-producing ILC2s through a TSLP-dependent mechanism.
CONCLUSION:
These data demonstrate that multiple pathogenic strains of RSV induce IL-13-producing ILC2 proliferation and activation through a TSLP-dependent mechanism in a murine model and suggest the potential therapeutic targeting of TSLP during severe RSV infection
How long before the end of inflation were observable perturbations produced?
We reconsider the issue of the number of e-foldings before the end of
inflation at which observable perturbations were generated. We determine a
plausible upper limit on that number for the standard cosmology which is around
60, with the expectation that the actual value will be up to 10 below this. We
also note a special property of the model which reduces the
uncertainties in that case and favours a higher value, giving a fairly definite
prediction of 64 e-foldings for that model. We note an extreme (and highly
implausible) situation where the number of e-foldings can be even higher,
possibly up to 100, and discuss the shortcomings of quantifying inflation by
e-foldings rather than by the change in . Finally, we discuss the impact of
non-standard evolution between the end of inflation and the present, showing
that again the expected number of e-foldings can be modified, and in some cases
significantly increased.Comment: 7 pages RevTeX4 file with one figure incorporated. Minor updates to
match version accepted by Physical Review
Supermassive black holes in scalar field galaxy halos
Ultra-light scalar fields provide an interesting alternative to WIMPS as halo
dark matter. In this paper we consider the effect of embedding a supermassive
black hole within such a halo, and estimate the absorption probability and the
accretion rate of dark matter onto the black hole. We show that the accretion
rate would be small over the lifetime of a typical halo, and hence that
supermassive central black holes can coexist with scalar field halos.Comment: 5 pages RevTex4, no figures. Updated file to match published versio
Calculation of the Ostriker-Vishniac Effect in Cold Dark Matter Models
We present a new derivation of the cosmic microwave background anisotropy
spectrum from the Ostriker-Vishniac effect for an open, flat, or closed
Universe, and calculate the anisotropy expected in cold dark-matter (CDM)
models. We provide simple semi-analytic fitting formulas for the Vishniac power
spectrum that can be used to evaluate the expected anisotropy in CDM models for
any arbitrary ionization history. In a flat Universe, CDM models normalized to
cluster abundances produce rms temperature anisotropies of 0.8--2.4 K on
arcminute angular scales for a constant ionization fraction of unity, whereas
an ionization fraction of 0.2 yields rms anisotropies of 0.3--0.8 K. In an
open and/or high-baryon-density Universe, the level of anisotropy is somewhat
higher. The signal in some of these models may be detectable with planned
interferometry experiments. The damping of the acoustic peaks in the
primary-anisotropy spectrum at degree angular scales depends primarily on the
optical depth and only secondarily on the epoch of reionization. On the other
hand, the amplitude of Ostriker-Vishniac anisotropies depends sensitively on
the epoch of reionization. Therefore, when combined with the estimate of the
reionization optical depth provided by maps of degree-scale anisotropies, the
Ostriker-Vishniac effect can provide a unique probe of the epoch of
reionization.Comment: 19 pages, 2 figures, Revtex. Phys. Rev. D, accepted. Final version to
be published, with minor changes to open universe scalin
Inflation, cold dark matter, and the central density problem
A problem with high central densities in dark halos has arisen in the context
of LCDM cosmologies with scale-invariant initial power spectra. Although n=1 is
often justified by appealing to the inflation scenario, inflationary models
with mild deviations from scale-invariance are not uncommon and models with
significant running of the spectral index are plausible. Even mild deviations
from scale-invariance can be important because halo collapse times and
densities depend on the relative amount of small-scale power. We choose several
popular models of inflation and work out the ramifications for galaxy central
densities. For each model, we calculate its COBE-normalized power spectrum and
deduce the implied halo densities using a semi-analytic method calibrated
against N-body simulations. We compare our predictions to a sample of dark
matter-dominated galaxies using a non-parametric measure of the density. While
standard n=1, LCDM halos are overdense by a factor of 6, several of our example
inflation+CDM models predict halo densities well within the range preferred by
observations. We also show how the presence of massive (0.5 eV) neutrinos may
help to alleviate the central density problem even with n=1. We conclude that
galaxy central densities may not be as problematic for the CDM paradigm as is
sometimes assumed: rather than telling us something about the nature of the
dark matter, galaxy rotation curves may be telling us something about inflation
and/or neutrinos. An important test of this idea will be an eventual consensus
on the value of sigma_8, the rms overdensity on the scale 8 h^-1 Mpc. Our
successful models have values of sigma_8 approximately 0.75, which is within
the range of recent determinations. Finally, models with n>1 (or sigma_8 > 1)
are highly disfavored.Comment: 13 pages, 6 figures. Minor changes made to reflect referee's
Comments, error in Eq. (18) corrected, references updated and corrected,
conclusions unchanged. Version accepted for publication in Phys. Rev. D,
scheduled for 15 August 200
Reconstructing the Inflaton Potential---in Principle and in Practice
Generalizing the original work by Hodges and Blumenthal, we outline a
formalism which allows one, in principle, to reconstruct the potential of the
inflaton field from knowledge of the tensor gravitational wave spectrum or the
scalar density fluctuation spectrum, with special emphasis on the importance of
the tensor spectrum. We provide some illustrative examples of such
reconstruction. We then discuss in some detail the question of whether one can
use real observations to carry out this procedure. We conclude that in
practice, a full reconstruction of the functional form of the potential will
not be possible within the foreseeable future. However, with a knowledge of the
dark matter components, it should soon be possible to combine
intermediate-scale data with measurements of large-scale cosmic microwave
background anisotropies to yield useful information regarding the potential.Comment: 39 pages plus 2 figures (upon request:[email protected]), LaTeX,
FNAL--PUB--93/029-A; SUSSEX-AST 93/3-
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