Obtaining the spacetime metric from cosmological observations

Recent galaxy redshift surveys have brought in a large amount of accurate cosmological data out to redshift 0.3, and future surveys are expected to achieve a high degree of completeness out to a redshift exceeding 1. Consequently, a numerical programme for determining the metric of the universe from observational data will soon become practical; and thereby realise the ultimate application of Einstein's equations. Apart from detailing the cosmic geometry, this would allow us to verify and quantify homogeneity, rather than assuming it, as has been necessary up to now, and to do that on a metric level, and not merely at the mass distribution level. This paper is the beginning of a project aimed at such a numerical implementation. The primary observational data from our past light cone consists of galaxy redshifts, apparent luminosities, angular diameters and number densities, together with source evolution functions, absolute luminosities, true diameters and masses of sources. Here we start with the simplest case, that of spherical symmetry and a dust equation of state, and execute an algorithm that determines the unknown metric functions from this data. We discuss the challenges of turning the theoretical algorithm into a workable numerical procedure, particularly addressing the origin and the maximum in the area distance. Our numerical method is tested with several artificial data sets for homogeneous and inhomogeneous models, successfully reproducing the original models. This demonstrates the basic viability of such a scheme. Although current surveys don't have sufficient completeness or accuracy, we expect this situation to change in the near future, and in the meantime there are many refinements and generalisations to be added.Comment: 26 pages, 10 figures. Minor changes to match the published versio

Shrinking II -- The Distortion of the Area Distance-Redshift Relation in Inhomogeneous Isotropic Universes

This paper and the others in the series challenge the standard model of the effects of gravitational lensing on observations at large distances. We show that due to the cumulative effect of lensing, areas corresponding to an observed solid angle can be quite different than would be estimated from the corresponding Friedmann-Lema\^{\i}tre model, even when averaged over large angular scales. This paper concentrates on the specific example of spherically symmetric but spatially inhomogeneous dust universes, the Lema\^{\i}tre-Tolman-Bondi models, and shows that radial lensing significantly distorts the area distance-redshift and density-redshift relations in these exact solutions compared with the standard ones for Friedmann-Lema\^{\i}tre models. Thus inhomogeneity may introduce significant errors into distance estimates based on the standard FL relations, even after all-sky averaging. In addition a useful new gauge choice is presented for these models, solving the problem of locating the past null cone exactly.Comment: Minor technical refinement, 16 pages, RevTex, 8 eps figure

Repeat courses of intravenous alefacept in patients with chronic plaque psoriasis provide consistent safety and efficacy

Background Psoriasis is a chronic, relapsing skin disease that may require multiple treatment courses. Alefacept targets the memory T cells implicated in psoriasis pathogenesis. This open-label study evaluated the safety and tolerability, efficacy, and pharmacodynamics of repeat courses of alefacept in men and women with chronic plaque psoriasis. This article reports the interim results of this ongoing study. Methods Patients ( n  = 174) who participated in previous phase II studies of alefacept were included in this retreatment study. Intravenous alefacept (7.5 mg) was administered once weekly for 12 weeks followed by 12 weeks of observation. Initial and subsequent retreatment courses were only given when, in the opinion of the investigators, disease had returned and necessitated treatment; CD4 + T-cell counts had to be at or above the lower limit of normal. Results Adverse events were similar regardless of the retreatment course. No opportunistic infections, rebound of disease, or flares were reported. Low titers of anti-alefacept antibodies occurred in a few patients without related safety issues. Sixty-six per cent of patients achieved a ≥ 50% reduction in the Psoriasis Area and Severity Index (PASI) at any time after the first dose of retreatment course 1. Patients who received two retreatment courses ( n  = 50) had consistent or improved responses after the second course; 64% and 68% of these patients achieved a ≥ 50% PASI improvement at any time after the first dose of retreatment courses 1 and 2, respectively. Alefacept selectively reduced memory T cells without cumulative effects. Conclusions Repeat courses of alefacept were well tolerated, and subsequent retreatment courses were at least as effective as the initial course of therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65825/1/j.1365-4362.2003.01793.x.pd

Retinoid-induced ossification of the posterior longitudinal ligament

Vitamin A and its synthetic congeners are known to produce a variety of skeletal abnormalities in patients on prolonged treatment with these medications. Two patients are described who developed posterior longitudinal ligament ossification following treatment with the synthetic retinoid 13-cis-retinoic acid. In both cases, this finding became apparent after other retinoid-induced skeletal abnormalities were observed and was less marked than the ossification of the anterior longitudinal ligament. Although spinal cord compression did not occur in our patients, patients on long-term retinoid therapy should be carefully observed for this complication.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46779/1/256_2004_Article_BF00355561.pd

Evaluation of Adrenal Suppression of a Lipid Enhanced, Topical Emollient Cream Formulation of Hydrocortisone Butyrate 0.1% in Treating Children with Atopic Dermatitis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75102/1/j.1525-1470.2007.00342.x.pd

The erythromycin breath test as a predictor of cyclosporine blood levels

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109915/1/cptclpt1990126.pd

Racial and Ethnic Disparities in Stroke Outcomes: A Scoping Review of Post-Stroke Disability Assessment Tools

Purpose: To identify how post-stroke disability outcomes are assessed in studies that examine racial/ethnic disparities and to map the identified assessment content to the International Classification of Functioning, Disability, and Health (ICF) across the time course of stroke recovery. Methods: We conducted a scoping review of the literature. Articles published between January 2001 and July 2017 were identified through Scopus, PubMed, CINAHL, and PsycINFO according to predefined inclusion and exclusion criteria. Results: We identified 1791 articles through database and hand-searching strategies. Of the articles, 194 met inclusion criteria for full-text review, and 41 met inclusion criteria for study inclusion. The included studies used a variety of outcome measures encompassing domains within the ICF: body functions, activities, participation, and contextual factors across the time course of stroke recovery. We discovered disproportionate representation among racial/ethnic groups in the post-stroke disability disparities literature. Conclusions: A wide variety of assessments are used to examine disparities in post-stroke disability across the time course of stroke recovery. Several studies have identified disparities through a variety of assessments; however, substantial problems abound from the assessments used including inconsistent use of assessments, lacking evidence on the validity of assessments among racial/ethnic groups, and inadequate representation among all racial/ethnic populations comprising the US. Implications for Rehabilitation An enhanced understanding of racial/ethnic disparities in post-stroke disability outcomes is inherently important among rehabilitation practitioners who frequently engage with racial/ethnic minority populations across the time course of stroke recovery. Clinicians should carefully consider the psychometric properties of assessment tools to counter potential racial bias. Clinicians should be aware that many assessments used in stroke rehabilitation lack cultural sensitivity and could result in inaccurate assessment findings

QSO Absorbing Galaxies at z<~1: Deep Imaging and Spectroscopy in the Field of 3C 336

We present very deep WFPC2 images and FOS spectroscopy from the Hubble Space Telescope (HST) together with numerous supporting ground-based observations of the field of the quasar 3C 336 ($z_{em}=0.927$). The observations are designed to investigate the nature of galaxies producing metal line absorption systems in the spectrum of the QSO. Along a single line of sight, we find at least 6 metal line absorption systems (of which 3 are newly discovered) ranging in redshift from 0.317 to 0.892. Through an extensive program of optical and IR imaging, QSO spectroscopy, and faint galaxy spectroscopy, we have identified 5 of the 6 metal line absorption systems with luminous (L_K > 0.1 L*_K) galaxies. These have morphologies ranging from very late-type spiral to S0, and exhibit a wide range of inclination and position angles with respect to the QSO sightline. The only unidentified absorber, despite our intensive search, is a damped Lyman $\alpha$ system at $z_{abs}=0.656$. Analysis of the absorption spectrum suggests that the metal abundances ([Fe/H]$=-1.2$) in this system are similar to those in damped systems at $z \sim 2$, and to the two other damped systems for which abundances have been determined at $z <1$. We have found no examples of intrinsically faint galaxies ($L < 0.1 L^{\ast}$) at small impact parameters that might have been missed as absorber candidates in our previous ground-based imaging and spectroscopic programs on MgII absorbing galaxies. There are no bright galaxies (L > 0.1 L_K) within 50h^{-1} kpc which do not produce detectable metal lines (of Mg II 2796, 2803 and/or C IV 1548, 1550) in the QSO spectrum. All of these results generally support the inferences which we have previously reached from a larger survey for absorption-selected galaxies at z\simlt 1.Comment: 32 pages latex (AAS v4.0 style). 8 Postscript figures (including HST plate) available at ftp://astro.caltech.edu/users/ccs/3c336_figs.ps.gz . Submitted to Ap

Aspects of meson properties in dense nuclear matter

We investigate the modification of meson spectral densities in dense nuclear matter at zero temperature. These effects are studied in a fully relativistic mean field model which goes beyond the linear density approximation and also includes baryon resonances. In particular, the role of N*(1520) and N*(1720) on the rho meson spectral density is highlighted. Even though the nucleon-nucleon loop and the nucleon-resonance loop contribute with the opposite sign, an overall reduction of rho meson mass is still observed at high density. Importantly, it is shown that the resonances cause substantial broadening of the rho meson spectral density in matter and also induces non-trivial momentum dependence. The spectral density of the a0 meson is also shown. We study the dispersion relations and collective oscillations induced by the rho meson propagation in nuclear matter together with the influence of the mixing of rho with the a0 meson. The relevant expression for the plasma frequency is also recovered analytically in the appropriate limit.Comment: 19 pages, 17 figure

Three Numerical Puzzles and the Top Quark's Chiral Weak-Moment

Versus the standard model's t --> W b decay helicity amplitudes, three numerical puzzles occur at the 0.1 % level when one considers the amplitudes in the case of an additional (f_M + f_E) coupling of relative strength 53 GeV. The puzzles are theoretical ones which involve the t --> W b decay helicity amplitudes in the two cases, the relative strength of this additional coupling, and the observed masses of these three particles. A deeper analytic realization is obtained for two of them. Equivalent realizations are given for the remaining one. An empirical consequence of these analytic realizations is that it is important to search for effects of a large chiral weak-moment of the top-quark, the effective mass-scale is about 53 GeV. A full theoretical resolution would include relating the origin of such a chiral weak-moment and the mass generation of the top-quark, the W-boson, and probably the b-quark.Comment: 18 pages, 1 postscript table (revised to better explain notation, model #1, add a little material...