Nickel Mixing in the Outer Layers of SN 1987A

Supernova 1987A remains the most well-observed and well-studied supernova to date. Observations produced excellent broad-band photometric and spectroscopic coverage over a wide wavelength range at all epochs. Here, we focus on the very early spectroscopic observations. Only recently have numerical models been of sufficient detail to accurately explain the observed spectra. In SN 1987A, good agreement has been found between observed and synthetic spectra for day one, but by day four, the predicted Balmer lines become much weaker than the observed lines. We present the results of work based on a radiation-hydrodynamic model by Blinnikov and collaborators. Synthetic non-LTE spectra generated from this model by the general radiation transfer code PHOENIX strongly support the theory that significant mixing of nickel into the outer envelope is required to maintain strong Balmer lines. Preliminary results suggest a lower limit to the average nickel mass of 1.0 \times 10^{-5} solar masses is required above 5000 \kmps by day four. PHOENIX models thus have the potential to be a sensitive probe for nickel mixing in the outer layers of a supernova.Comment: 16 pages, 7 figures, ApJ, v556 2001 (in press

Misperceptions in Intergroup Conflict: Disagreeing About What We Disagree About

Two studies examined misperceptions of disagreement in partisan social conflicts, namely, in the debates over abortion (Study 1) and politics (Study 2). We observed that partisans tend to exaggerate differences of opinion with their adversaries. Further, we found that perceptions of disagreement were more pronounced for values that were central to the perceiver\u27s own ideology than for values that were central to the ideology of the perceiver\u27s adversaries. To the extent that partisans assumed disagreement concerning personally important values, they were also inaccurate in perceiving their adversaries\u27 actual opinions. Discussion focuses on the cognitive mechanisms underlying misperceptions of disagreement and strategies for reducing inter- group conflict

Strategic toolkits: seniority, usage and performance in the German SME machinery and equipment sector

This paper examines the strategic tool kit, from a human resource management (HRM) perspective, in terms of usage and impact. Research to date has tended to consider usage, assuming to a certain extent that knowledge and understanding of particular tools suggest that practitioners value them. The research on which this paper is based builds upon the idea that usage indicates satisfaction, but develops the usage theme to investigate which decision-makers are actually engaged in both tool appliance and the strategic process. Of particular interest to the researchers are the educational background, age and seniority of the decision-makers. In addition, potential links with HRM and organizational performance are also explored. The context of the research, the German machinery and equipment sector, provides an insight into the industry's ability to sustain growth in face of increasing international competition. The paper calls for a greater awareness, from a human resource perspective, and utilization of strategic management practice and associated decision-making aids

Calcium Supplementation Increases Blood Creatinine Concentration in a Randomized Controlled Trial

Background: Calcium supplements are widely used among older adults for osteoporosis prevention and treatment. However, their effect on creatinine levels and kidney function has not been well studied. Methods: We investigated the effect of calcium supplementation on blood creatinine concentration in a randomized controlled trial of colorectal adenoma chemoprevention conducted between 2004–2013 at 11 clinical centers in the United States. Healthy participants (N=1,675) aged 45–75 with a history of colorectal adenoma were assigned to daily supplementation with calcium (1200 mg, as carbonate), vitamin D3 (1000 IU), both, or placebo for three or five years. Changes in blood creatinine and total calcium concentration were measured after one year of treatment and multiple linear regression was used to estimate effects on creatinine concentrations. Results: After one year of treatment, blood creatinine was 0.01360.006 mg/dL higher on average among participants randomized to calcium compared to placebo after adjustment for other determinants of creatinine (P = 0.03). However, the effect of calcium treatment appeared to be larger among participants who consumed the most alcohol (2–6 drinks/day) or whose estimated glomerular filtration rate (eGFR) was less than 60 ml/min/1.73 m2 at baseline. The effect of calcium treatment on creatinine was only partially mediated by a concomitant increase in blood total calcium concentration and was independent of randomized vitamin D treatment. There did not appear to be further increases in creatinine after the first year of calcium treatment. Conclusions: Among healthy adults participating in a randomized clinical trial, daily supplementation with 1200 mg of elemental calcium caused a small increase in blood creatinine. If confirmed, this finding may have implications for clinical and public health recommendations for calcium supplementation

Association between adenoma location and risk of recurrence

The biological environment varies across the colorectum and may therefore differently affect neoplastic growth in the proximal and distal colon. The aim of the study was to evaluate the risk for recurrent adenomas and their anatomic location based on adenoma location at baseline colonoscopy

Randomized controlled trials: who fails run-in?

Background: Early identification of participants at risk of run-in failure (RIF) may present opportunities to improve trial efficiency and generalizability. Methods: We conducted a partial factorial-design, randomized, controlled trial of calcium and vitamin D to prevent colorectal adenoma recurrence at 11 centers in the United States. At baseline, participants completed two self-administered questionnaires (SAQs) and a questionnaire administered by staff. Participants in the full factorial randomization (calcium, vitamin D, both, or neither) received a placebo during a 3-month single-blinded run-in; women electing to take calcium enrolled in a two-group randomization (calcium with vitamin D, or calcium alone) and received calcium during the run-in. Using logistic regression models, we examined baseline factors associated with RIF in three subgroups: men (N = 1606) and women (N = 301) in the full factorial randomization and women in the two-group randomization (N = 666). Results: Overall, 314/2573 (12 %) participants failed run-in; 211 (67 %) took fewer than 80 % of their tablets (poor adherence), and 103 (33 %) withdrew or were uncooperative. In multivariable models, 8- to 13-fold variation was seen by study center in odds of RIF risk in the two largest groups. In men, RIF decreased with age (adjusted odds ratio [OR] per 5 years 0.85 [95 % confidence interval, CI; 0.76-0.96]) and was associated with being single (OR 1.65 [95 % CI; 1.10-2.47]), not graduating from high school (OR 2.77 [95 % CI; 1.58-4.85]), and missing SAQ data (OR 1.97 [1.40-2.76]). Among women, RIF was associated primarily with health-related factors; RIF risk was lower with higher physical health score (OR 0.73 [95 % CI; 0.62-0.86]) and baseline multivitamin use (OR 0.44 [95 % CI; 0.26-0.75]). Women in the 5-year colonoscopy surveillance interval were at greater risk of RIF than those with 3-year follow-up (OR 1.91 [95 % CI; 1.08-3. 37]), and the number of prescription medicines taken was also positively correlated with RIF (p = 0.03). Perceived toxicities during run-in were associated with 12- to 29-fold significantly increased odds of RIF. Conclusions: There were few common baseline predictors of run-in failure in the three randomization groups. However, heterogeneity in run-in failure associated with study center, and missing SAQ data reflect potential opportunities for intervention to improve trial efficiency and retention

Factors Associated With Shorter Colonoscopy Surveillance Intervals for Patients With Low-Risk Colorectal Adenomas and Effects on Outcome

BACKGROUND & AIMS: Endoscopists do not routinely follow guidelines to survey individuals with low-risk adenomas (LRAs; 1-2 small tubular adenomas, < 1 cm) every 5-10 years for colorectal cancer; many recommend shorter surveillance intervals for these individuals. We aimed to identify the reasons that endoscopists recommend shorter surveillance intervals for some individuals with LRAs and determine whether timing affects outcomes at follow-up examinations. METHODS: We collected data from 1560 individuals (45-75 years old) who participated in a prospective chemoprevention trial (of vitamin D and calcium) from 2004 through 2008. Participants in the trial had at least 1 adenoma, detected at their index colonoscopy, and were recommended to receive follow-up colonoscopy examinations at 3 or 5 years after adenoma identification, as recommended by the endoscopist. For this analysis we collected data from only participants with LRAs. These data included characteristics of participants and endoscopists and findings from index and follow-up colonoscopies. Primary endpoints were frequency of recommending shorter (3-year) vs longer (5-year) surveillance intervals, factors associated with these recommendations, and effect on outcome, determined at the follow-up colonoscopy. RESULTS: A 3-year surveillance interval was recommended for 594 of the subjects (38.1%). Factors most significantly associated with recommendation of 3-year vs a 5-year surveillance interval included African American race (relative risk [RR] to white, 1.41; 95% confidence interval [CI], 1.14-1.75), Asian/Pacific Islander ethnicity (RR to white, 1.7; 95% CI, 1.22-2.43), detection of 2 adenomas at the index examination (RR vs 1 adenoma, 1.47; 95% CI, 1.27-1.71), more than 3 serrated polyps at the index examination (RR=2.16, 95% CI, 1.59-2.93), or index examination with fair or poor quality bowel preparation (RR vs excellent quality, 2.16; 95% CI, 1.66-2.83). Other factors that had a significant association with recommendation for a 3-year surveillance interval included family history of colorectal cancer and detection of 1-2 serrated polyps at the index examination. In comparisons of outcomes, we found no significant differences between the 3-year vs 5-year recommendation groups in proportions of subjects found to have 1 or more adenomas (38.8% vs 41.7% respectively; P = .27), advanced adenomas (7.7% vs 8.2%; P = .73) or clinically significant serrated polyps (10.0% vs 10.3%; P = .82) at the follow-up colonoscopy. CONCLUSIONS: Possibly influenced by patients' family history, race, quality of bowel preparation, or number or size of polyps, endoscopists frequently recommend 3-year surveillance intervals instead of guideline-recommended intervals of 5 years or longer for individuals with LRAs. However, at the follow-up colonoscopy, similar proportions of participants have 1 or more adenomas, advanced adenomas, or serrated polyps. These findings support the current guideline recommendations of performing follow-up examinations of individuals with LRAs at least 5 years after the index colonoscopy

Type II Supernovae as Probes of Cosmology

- Constraining the cosmological parameters and understanding Dark Energy have tremendous implications for the nature of the Universe and its physical laws. - The pervasive limit of systematic uncertainties reached by cosmography based on Cepheids and Type Ia supernovae (SNe Ia) warrants a search for complementary approaches. - Type II SNe have been shown to offer such a path. Their distances can be well constrained by luminosity-based or geometric methods. Competing, complementary, and concerted efforts are underway, to explore and exploit those objects that are extremely well matched to next generation facilities. Spectroscopic follow-up will be enabled by space- based and 20-40 meter class telescopes. - Some systematic uncertainties of Type II SNe, such as reddening by dust and metallicity effects, are bound to be different from those of SNe Ia. Their stellar progenitors are known, promising better leverage on cosmic evolution. In addition, their rate - which closely tracks the ongoing star formation rate - is expected to rise significantly with look- back time, ensuring an adequate supply of distant examples. - These data will competitively constrain the dark energy equation of state, allow the determination of the Hubble constant to 5%, and promote our understanding of the processes involved in the last dramatic phases of massive stellar evolution.Comment: Science white paper, submitted to the Decadal committee Astro201

A Randomized Trial of Rofecoxib for the Chemoprevention of Colorectal Adenomas

BACKGROUND & AIMS: In human and animal studies, nonsteroidal anti-inflammatory drugs have been associated with a reduced risk of colorectal neoplasia. Although the underlying mechanisms are unknown, inhibition of cyclooxygenase (COX), particularly COX-2, is thought to play a role. We conducted a randomized, placebo-controlled, double-blind trial to assess whether use of the selective COX-2 inhibitor rofecoxib would reduce the risk of colorectal adenomas. METHODS: We randomized 2587 subjects with a recent history of histologically confirmed adenomas to receive daily placebo or 25 mg rofecoxib. Randomization was stratified by baseline use of cardioprotective aspirin. Colonoscopic follow-up evaluation was planned for 1 and 3 years after randomization. The primary end point was all adenomas diagnosed during 3 years' treatment. In a modified intent-to-treat analysis, we computed the relative risk of any adenoma after randomization, using Mantel-Haenszel statistics stratified by low-dose aspirin use at baseline. RESULTS: Adenoma recurrence was less frequent for rofecoxib subjects than for those randomized to placebo (41% vs 55%; P < .0001; relative risk [RR], 0.76; 95% confidence interval [CI], 0.69-0.83). Rofecoxib also conferred a reduction in risk of advanced adenomas (P < .01). The chemopreventive effect was more pronounced in the first year (RR, 0.65; 95% CI, 0.57-0.73) than in the subsequent 2 years (RR, 0.81; 95% CI, 0.71-0.93). As reported previously, rofecoxib was associated with increased risks of significant upper gastrointestinal events and serious thrombotic cardiovascular events. CONCLUSIONS: In this randomized trial, rofecoxib significantly reduced the risk of colorectal adenomas, but also had serious toxicity

Variants Downstream of the Ornithine Decarboxylase Gene Influence Risk of Colorectal Adenoma and Aspirin Chemoprevention

Increased mucosal polyamine levels and ornithine decarboxylase (ODC) activity are associated with an increased risk of colorectal neoplasia, and aspirin treatment reduces risk. Previous studies suggest that a single nucleotide polymorphism (SNP) in the promoter of the ODC gene (rs2302615) may be associated with adenoma risk and/or response to aspirin chemoprevention. However, a comprehensive investigation of common genetic variation in the region of ODC gene is lacking. Using a tag SNP approach, we investigated associations between genotype or haplotype and adenoma risk among a cohort of 792 white non-Hispanic participants in a randomized trial of aspirin. Generalized linear regression was used to compute relative risks (RRs) and 95% confidence intervals (95% CIs) adjusted for age and sex. The false discovery rate was used to account for multiple testing. Interactions terms were used to assess whether genotype modified the effect of aspirin treatment. Of 15 SNPs analyzed, 7 were statistically significantly associated with adenoma risk. However, in multiple SNP regression models, only 2 of these, located downstream of the gene, were independently associated with risk: rs11694911 (1.29 RR, 1.08–1.53 95% CI, P=0.005) and rs2430420 (1.20 RR, 1.03–1.40 95% CI, P=0.022). In addition, there was evidence that rs2430420 and rs28362380 modified the effect of aspirin treatment, whereas the previously investigated SNP, rs2302615, had no statistically significant main effect or interaction with aspirin treatment. Our findings suggest that common genetic variants located downstream (3’) of the ODC gene influence risk of colorectal adenoma and may also impact the efficacy of aspirin chemoprevention