Formation and coalescence of cosmological supermassive-black-hole binaries in supermassive-star collapse.

We study the collapse of rapidly rotating supermassive stars that may have formed in the early Universe. By self-consistently simulating the dynamics from the onset of collapse using three-dimensional general-relativistic hydrodynamics with fully dynamical spacetime evolution, we show that seed perturbations in the progenitor can lead to the formation of a system of two high-spin supermassive black holes, which inspiral and merge under the emission of powerful gravitational radiation that could be observed at redshifts z is approximately equal or > to 10 with the DECIGO or Big Bang Observer gravitational-wave observatories, assuming supermassive stars in the mass range 10(4)-10(6)M[symbol: see text]. The remnant is rapidly spinning with dimensionless spin a*=0.9. The surrounding accretion disk contains ~10% of the initial mass.

Dynamics and gravitational wave signature of collapsar formation.

We perform 3+1 general relativistic simulations of rotating core collapse in the context of the collapsar model for long gamma-ray bursts. We employ a realistic progenitor, rotation based on results of stellar evolution calculations, and a simplified equation of state. Our simulations track self-consistently collapse, bounce, the postbounce phase, black hole formation, and the subsequent early hyperaccretion phase. We extract gravitational waves from the spacetime curvature and identify a unique gravitational wave signature associated with the early phase of collapsar formation.

The effect of weight training on bone mineral density and bone turnover in postmenopausal breast cancer survivors with bone loss: a 24-month randomized controlled trial.

SUMMARY: This study examined whether 24 months of weight training exercises enhanced the effectiveness of risedronate, calcium, and vitamin D in maintaining or improving bone mineral density (BMD) in 223 postmenopausal breast cancer survivors. Subjects who were > or =50% adherent to exercise had no improvement in BMD but were less likely to lose BMD. INTRODUCTION: This study examined whether (1) postmenopausal breast cancer survivors (BCS) with bone loss taking 24 months of risedronate, calcium, and vitamin D had increased bone mineral density (BMD) at the total hip, femoral neck, L1-L4 spine, total radius and 33% radius, and decreased bone turnover; (2) subjects who also participated in strength/weight training (ST) exercises had greater increases in BMD and greater decreases in bone turnover; and (3) subjects who also exercised were more likely to preserve (at least maintain) BMD. METHODS: Postmenopausal BCS (223) were randomly assigned to exercise plus medication or medication only groups. Both groups received 24 months of 1,200 mg of calcium and 400 IU of vitamin D daily and 35 mg of risedronate weekly, and the exercise group additionally had ST exercises twice weekly. RESULTS: After 24 months, women who took medications without exercising had significant improvements in BMD at the total hip (+1.81%) and spine (+2.85%) and significant decreases in Alkphase B (-8.7%) and serum NTx (-16.7%). Women who also exercised had additional increases in BMD at the femoral neck (+0.29%), total hip (+0.34%), spine (+0.23%), total radius (+0.30%), and additional decreases in Alkphase B (-2.4%) and Serum NTx (-6.5%). Additional changes in BMD and bone turnover with exercise were not significant. Subjects who were > or =50% adherent to exercise were less likely to lose BMD at the total hip (chi-square [1] = 4.66, p = 0.03) and femoral neck (chi-square [1] = 4.63, p = 0.03). CONCLUSION: Strength/weight training exercises may prevent loss of BMD in postmenopausal BCS at risk for bone loss.

Generic gravitational-wave signals from the collapse of rotating stellar cores.

We perform general relativistic (GR) simulations of stellar core collapse to a protoneutron star, using a microphysical equation of state (EOS) and an approximation of deleptonization. We show that for a wide range of rotation rates and profiles the gravitational-wave (GW) burst signals from the core bounce are generic, known as type I. In our systematic study, using both GR and Newtonian gravity, we identify and quantify the influence of rotation, the EOS, and deleptonization on this result. Such a generic type of signal templates will facilitate a more efficient search in current and future GW detectors of both interferometric and resonant type.

3D collapse of rotating stellar iron cores in general relativity including deleptonization and a nuclear equation of state.

We present 2D and 3D simulations of the collapse of rotating stellar iron cores in general relativity employing a nuclear equation of state and an approximate treatment of deleptonization. We compare fully general relativistic and conformally flat evolutions and find that the latter treatment is sufficiently accurate for the core-collapse supernova problem. We focus on gravitational wave (GW) emission from rotating collapse, bounce, and early postbounce phases. Our results indicate that the GW signature of these phases is much more generic than previously estimated. We also track the growth of a nonaxisymmetric instability in one model, leading to strong narrow-band GW emission.

Bone mineral density in postmenopausal breast cancer survivors.

PURPOSE: The overall purpose of this longitudinal 18-month study was to test the feasibility and effectiveness of a multicomponent intervention for prevention and treatment of osteoporosis. The purpose of this article is to describe the baseline bone mineral density (BMD) findings for 30 postmenopausal women and to compare these BMD findings to time since menopause, body mass index, and tamoxifen use. DATA SOURCES: Baseline data of BMD findings for 30 postmenopausal women, who have had a variety of treatments including surgery, adjuvant chemotherapy and or tamoxifen, and are enrolled in the 18-month longitudinal study. A demographic questionnaire and a three day dietary record were used to collect baseline data. CONCLUSIONS: Eighty percent of the women with breast cancer history had abnormal BMDs at baseline (t-scores below -1.00 SD). Thinner women showed a greater risk for accelerated trabecular bone loss at the spine and hip. IMPLICATIONS FOR PRACTICE: These findings suggest the need for early BMD assessments and for aggressive health promotion intervention strategies that include a multifaceted protocol of drug therapy for bone remodeling, 1500 mg of daily calcium, 400 IU vitamin D and a strength weight training program that is implemented immediately following chemotherapy treatment and menopause in this high risk population of women.