1,041 research outputs found
Inter-ethnic Issues in Lorraine Hansberry\u27s The Sign in Sidney Brustein\u27s Window by Steven R. Carter
When Lorraine Hansberry\u27s second produced play, The Sign in Sidney Brustein\u27s Window, opened on Broadway in 1964, some white critics expressed surprise that her protagonist was Jewish rather than black and some blacks were disappointed or even outraged by this, feeling that she was deserting the cause and trying too hard to win acclaim as a universal writer.[1] Others from both groups, of course, warmly defended her
A statnet Tutorial
The statnet suite of R packages contains a wide range of functionality for the statistical analysis of social networks, including the implementation of exponential-family random graph (ERG) models. In this paper we illustrate some of the functionality of statnet through a tutorial analysis of a friendship network of 1,461 adolescents.
ergm: A Package to Fit, Simulate and Diagnose Exponential-Family Models for Networks
We describe some of the capabilities of the ergm package and the statistical theory underlying it. This package contains tools for accomplishing three important, and inter-related, tasks involving exponential-family random graph models (ERGMs): estimation, simulation, and goodness of fit. More precisely, ergm has the capability of approximating a maximum likelihood estimator for an ERGM given a network data set; simulating new network data sets from a fitted ERGM using Markov chain Monte Carlo; and assessing how well a fitted ERGM does at capturing characteristics of a particular network data set.
statnet: Software Tools for the Representation, Visualization, Analysis and Simulation of Network Data
statnet is a suite of software packages for statistical network analysis. The packages implement recent advances in network modeling based on exponential-family random graph models (ERGM). The components of the package provide a comprehensive framework for ERGM-based network modeling, including tools for model estimation, model evaluation, model-based network simulation, and network visualization. This broad functionality is powered by a central Markov chain Monte Carlo (MCMC) algorithm. The coding is optimized for speed and robustness.
UCDs in the Coma Cluster
As part of the HST/ACS Coma Cluster Treasury Survey, we have undertaken a
Keck/LRIS spectroscopic campaign to determine membership for faint dwarf
galaxies. In the process, we discovered a population of Ultra Compact Dwarf
galaxies (UCDs) in the core region of the Coma cluster. At the distance of
Coma, UCDs are expected to have angular sizes 0.01 < R_e < 0.2 arcsec. With ACS
imaging, we can resolve all but the smallest ones with careful fitting.
Candidate UCDs were chosen based on magnitude, color, and degree of resolution.
We spectroscopically confirm 27 objects as bona fide UCD members of the Coma
cluster, a 60% success rate for objects targeted with M_R < -12. We attribute
the high success rate in part to the high resolution of HST data and to an
apparent large population of UCDs in Coma. We find that the UCDs tend to be
strongly clustered around giant galaxies, at least in the core region of the
cluster, and have a distribution and colors that are similar to globular
clusters. These findings suggest that UCDs are not independent galaxies, but
rather have a star cluster origin. This current study provides the dense
environment datapoint necessary for understanding the UCD population.Comment: 6 pages, 9 figures, to appear in the conference proceedings of "A
Universe of Dwarf Galaxies" (Lyon, June 14-18, 2010
Anthropic reasoning in multiverse cosmology and string theory
Anthropic arguments in multiverse cosmology and string theory rely on the
weak anthropic principle (WAP). We show that the principle, though ultimately a
tautology, is nevertheless ambiguous. It can be reformulated in one of two
unambiguous ways, which we refer to as WAP_1 and WAP_2. We show that WAP_2, the
version most commonly used in anthropic reasoning, makes no physical
predictions unless supplemented by a further assumption of "typicality", and we
argue that this assumption is both misguided and unjustified. WAP_1, however,
requires no such supplementation; it directly implies that any theory that
assigns a non-zero probability to our universe predicts that we will observe
our universe with probability one. We argue, therefore, that WAP_1 is
preferable, and note that it has the benefit of avoiding the inductive
overreach characteristic of much anthropic reasoning.Comment: 7 pages. Expanded discussion of selection effects and some minor
clarifications, as publishe
Cell matrix methodologies for integrated circuit design
Journal ArticleA class of integrated circuit design and implementation methodologies is described. These techniques are unique in that they simultaneously model both function and interconnect using cells. These cells are designed such that cell adjacency normally implies interconnection. The absence of an interconnection is explicitly modeled as a wire break between adjacent cells. These methodologies have the potential to greatly simplify and shorten the design process since some design steps are either eliminated or merged with others. They permit near custom layout density while reducing design time over full custom design by up to thirty times and over gate array design by up to four times
The impact of education inequality on rheumatoid arthritis risk is mediated by smoking and body mass index: mendelian randomization study
Objective
To estimate the causal relationship between educational attainment—as a proxy for socioeconomic inequality—and risk of RA, and quantify the roles of smoking and BMI as potential mediators.
Methods
Using the largest genome-wide association studies (GWAS), we performed a two‐sample Mendelian randomization (MR) study of genetically predicted educational attainment (instrumented using 1265 variants from 766 345 individuals) and RA (14 361 cases, 43 923 controls). We used two-step MR to quantify the proportion of education’s effect on RA mediated by smoking exposure (as a composite index capturing duration, heaviness and cessation, using 124 variants from 462 690 individuals) and BMI (517 variants, 681 275 individuals), and multivariable MR to estimate proportion mediated by both factors combined.
Results
Each S.D. increase in educational attainment (4.2 years of schooling) was protective of RA (odds ratio 0.37; 95% CI: 0.31, 0.44). Higher educational attainment was also protective for smoking exposure (β = −0.25 S.D.; 95% CI: −0.26, −0.23) and BMI [β = −0.27 S.D. (∼1.3 kg/m2); 95% CI: −0.31, −0.24]. Smoking mediated 24% (95% CI: 13%, 35%) and BMI 17% (95% CI: 11%, 23%) of the total effect of education on RA. Combined, the two risk factors explained 47% (95% CI: 11%, 82%) of the total effect.
Conclusion
Higher educational attainment has a protective effect on RA risk. Interventions to reduce smoking and excess adiposity at a population level may reduce this risk, but a large proportion of education’s effect on RA remains unexplained. Further research into other risk factors that act as potentially modifiable mediators are required
A clinical and cost-effectiveness analysis of the HeartMate 3 left ventricular assist device for transplant-ineligible patients: a United Kingdom perspective
Background: The clinical and cost-effectiveness of left ventricular assist device (LVAD) therapy for patients with advanced heart failure (HF) who are ineligible for heart transplantation is debated in the UK. This study develops an indirect comparison between the fully magnetically levitated HeartMate 3 (HM 3) LVAD and medical therapy (MT) to evaluate expected clinical and cost-effectiveness in the UK National Health Service (NHS) context. Methods: We performed an economic analysis comparing the HM3 pump against the HeartMate II LVAD (MOMENTUM 3), and then another analysis comparing MT with the first- and second-generation HeartMate XVE pump LVAD and HeartMate II LVAD for the same patient population (REMATCH and ROADMAP, respectively). By bridging those 2 analyses, an indirect comparison between HM3 and MT in the form of a network meta-analysis was developed. A literature search was performed to select the most appropriate pair of studies for this purpose. Outcomes were adjusted to produce Kaplan-Meier curves for the cost-effectiveness evaluation by using a decision-analytic model. Data were extrapolated linearly over a 5-year time horizon. Uncertainty and additional scenarios were addressed by one-way and probabilistic sensitivity analysis. Local costs and health utility were used from England, thereby representing the UK context. Results: The incremental cost-effectiveness ratio (ICER) for LVAD vs MT in transplant ineligible patients with advanced HF was estimated to be £47,361 per quality-adjusted life year gained, with a 97.1% probability of being cost-effective at £50,000. In a subgroup of patients who are inotropic therapy dependent (INTERMACS 1-3 severity profile), the ICER was £45,616, while for a population with less-ill ambulatory HF (INTERMACS profile 4-7) the ICER changed to £64,051. Conclusions: This study provides evidence that HM3 LVAD therapy in advanced HF patients ineligible for heart transplantation may be cost-effective compared to MT in the NHS UK-England context. The ICER is lowest for patients dependent on inotropic support, but exceeds the willingness to pay threshold of £50,000 in ambulatory noninotropic therapy dependent advanced HF patients
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