Extreme mass ratio inspiral rates: dependence on the massive black hole mass

We study the rate at which stars spiral into a massive black hole (MBH) due to the emission of gravitational waves (GWs), as a function of the mass M of the MBH. In the context of our model, it is shown analytically that the rate approximately depends on the MBH mass as M^{-1/4}. Numerical simulations confirm this result, and show that for all MBH masses, the event rate is highest for stellar black holes, followed by white dwarfs, and lowest for neutron stars. The Laser Interferometer Space Antenna (LISA) is expected to see hundreds of these extreme mass ratio inspirals per year. Since the event rate derived here formally diverges as M->0, the model presented here cannot hold for MBHs of masses that are too low, and we discuss what the limitations of the model are.Comment: Accepted to CQG, special LISA issu

Impact of metabolic comorbidity on the association between body mass index and heatlh-related quality of life: a Scotland-wide cross-sectional study of 5,608 participants

<p/>Background: The prevalence of obesity is rising in Scotland and globally. Overall, obesity is associated with increased morbidity, mortality and reduced health-related quality of life. Studies suggest that "healthy obesity" (obesity without metabolic comorbidity) may not be associated with morbidity or mortality. Its impact on health-related quality of life is unknown. <p/>Methods: We extracted data from the Scottish Health Survey on self-reported health-related quality of life, body mass index (BMI), demographic information and comorbidity. SF-12 responses were converted into an overall health utility score. Linear regression analyses were used to explore the association between BMI and health utility, stratified by the presence or absence of metabolic comorbidity (diabetes, hypertension, hypercholesterolemia or cardiovascular disease), and adjusted for potential confounders (age, sex and deprivation quintile). <p/>Results: Of the 5,608 individuals, 3,744 (66.8%) were either overweight or obese and 921 (16.4%) had metabolic comorbidity. There was an inverted U-shaped relationship whereby health utility was highest among overweight individuals and fell with increasing BMI. There was a significant interaction with metabolic comorbidity (p = 0.007). Individuals with metabolic comorbidty had lower utility scores and a steeper decline in utility with increasing BMI (morbidly obese, adjusted coefficient: -0.064, 95% CI -0.115, -0.012, p = 0.015 for metabolic comorbidity versus -0.042, 95% CI -0.067, -0.018, p = 0.001 for no metabolic comorbidity). <p/>Conclusions: The adverse impact of obesity on health-related quality of life is greater among individuals with metabolic comorbidity. However, increased BMI is associated with reduced health-related quality of life even in the absence of metabolic comorbidity, casting doubt on the notion of "healthy obesity"

Galaxy Collisions - Dawn of a New Era

The study of colliding galaxies has progressed rapidly in the last few years, driven by observations with powerful new ground and space-based instruments. These instruments have used for detailed studies of specific nearby systems, statistical studies of large samples of relatively nearby systems, and increasingly large samples of high redshift systems. Following a brief summary of the historical context, this review attempts to integrate these studies to address the following key issues. What role do collisions play in galaxy evolution, and how can recently discovered processes like downsizing resolve some apparently contradictory results of high redshift studies? What is the role of environment in galaxy collisions? How is star formation and nuclear activity orchestrated by the large scale dynamics, before and during merger? Are novel modes of star formation involved? What are we to make of the association of ultraluminous X-ray sources with colliding galaxies? To what do degree do mergers and feedback trigger long-term secular effects? How far can we push the archaeology of individual systems to determine the nature of precursor systems and the precise effect of the interaction? Tentative answers to many of these questions have been suggested, and the prospects for answering most of them in the next few decades are good.Comment: 44 pages, 9 figures, review article in press for Astrophysics Update Vol.

The Galactic Center Black Hole Laboratory

The super-massive 4 million solar mass black hole Sagittarius~A* (SgrA*) shows flare emission from the millimeter to the X-ray domain. A detailed analysis of the infrared light curves allows us to address the accretion phenomenon in a statistical way. The analysis shows that the near-infrared flare amplitudes are dominated by a single state power law, with the low states in SgrA* limited by confusion through the unresolved stellar background. There are several dusty objects in the immediate vicinity of SgrA*. The source G2/DSO is one of them. Its nature is unclear. It may be comparable to similar stellar dusty sources in the region or may consist predominantly of gas and dust. In this case a particularly enhanced accretion activity onto SgrA* may be expected in the near future. Here the interpretation of recent data and ongoing observations are discussed.Comment: 30 pages - 7 figures - accepted for publication by Springer's "Fundamental Theories of Physics" series; summarizing GC contributions of 2 conferences: 'Equations of Motion in Relativistic Gravity' at the Physikzentrum Bad Honnef, Bad Honnef, Germany, (Feb. 17-23, 2013) and the COST MP0905 'The Galactic Center Black Hole Laboratory' Granada, Spain (Nov. 19 - 22, 2013

Proliferation and aneusomy predict survival of young patients with astrocytoma grade II

The clinical course of astrocytoma grade II (AII) is highly variable and not reflected by histological characteristics. As one of the best prognostic factors, higher age identifies rapid progressive A II. For patients over 35 years of age, an aggressive treatment is normally propagated. For patients under 35 years, there is no clear guidance for treatment choices, and therefore also the necessity of histopathological diagnosis is often questioned. We studied the additional prognostic value of the proliferation index and the detection of genetic aberrations for patients with A II. The tumour samples were obtained by stereotactic biopsy or tumour resection and divided into two age groups, that is 18–34 years (n=19) and 35 years (n=28). Factors tested included the proliferation (Ki-67) index, and numerical aberrations for chromosomes 1, 7, and 10, as detected by in situ hybridisation (ISH). The results show that age is a prognostic indicator when studied in the total patient group, with patients above 35 years showing a relatively poor prognosis. Increased proliferation index in the presence of aneusomy appears to identify a subgroup of patients with poor prognosis more accurately than predicted by proliferation index alone. We conclude that histologically classified cases of A II comprise a heterogeneous group of tumours with different biological and genetic constitution, which exhibit a highly variable clinical course. Immunostaining for Ki-67 in combination with the detection of aneusomy by ISH allows the identification of a subgroup of patients with rapidly progressive A II. This is an extra argument not to defer stereotactic biopsy in young patients with radiological suspicion of A II

A Measurement of the Decay Asymmetry Parameters in \Xi_{c}^{0}\to \X^{-}\pi^{+}

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the $\Xi_c^{0}$ decay asymmetry parameter in the decay $\Xi_c^{0} \to \Xi^{-} \pi^+$. We find $\alpha_{\Xi_c^{0}} \alpha_{\Xi} = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}$, using the world average value of $\alpha_{\Xi} = -0.456 \pm 0.014$ we obtain $\alpha_{\Xi_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(syst)}$. The physically allowed range of a decay asymmetry parameter is $-1<\alpha<+1$. Our result prefers a negative value: $\alpha_{\Xi_c^{0}}$ is $<0.1$ at the 90% CL. The central value occupies the middle of the theoretically expected range but is not yet precise enough to choose between models.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN