Accretion Disks Around Black Holes: Twenty Five Years Later

We study the progress of the theory of accretion disks around black holes in last twenty five years and explain why advective disks are the best bet in explaining varied stationary and non-stationary observations from black hole candidates. We show also that the recently proposed advection dominated flows are incorrect.Comment: 30 Latex pages including figures. Kluwer Style files included. Appearing in `Observational Evidence for Black Holes in the Universe', ed. Sandip K. Chakrabarti, Kluwer Academic Publishers (DORDRECHT: Holland

The RR Lyrae Distance Scale

We review seven methods of measuring the absolute magnitude M_V of RR Lyrae stars in light of the Hipparcos mission and other recent developments. We focus on identifying possible systematic errors and rank the methods by relative immunity to such errors. For the three most robust methods, statistical parallax, trigonometric parallax, and cluster kinematics, we find M_V (at [Fe/H] = -1.6) of 0.77 +/- 0.13, 0.71 +/- 0.15, 0.67 +/- 0.10. These methods cluster consistently around 0.71 +/- 0.07. We find that Baade-Wesselink and theoretical models both yield a broad range of possible values (0.45-0.70 and 0.45-0.65) due to systematic uncertainties in the temperature scale and input physics. Main-sequence fitting gives a much brighter M_V = 0.45 +/- 0.04 but this may be due to a difference in the metallicity scales of the cluster giants and the calibrating subdwarfs. White-dwarf cooling-sequence fitting gives 0.67 +/- 0.13 and is potentially very robust, but at present is too new to be fully tested for systematics. If the three most robust methods are combined with Walker's mean measurement for 6 LMC clusters, V_{0,LMC} = 18.98 +/- 0.03 at [Fe/H] = -1.9, then mu_{LMC} = 18.33 +/- 0.08.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles', A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 21 pages including 1 table; uses Kluwer's crckapb.sty LaTeX style file, enclose

Contrasting Epidemic Histories Reveal Pathogen-Mediated Balancing Selection on Class II MHC Diversity in a Wild Songbird

The extent to which pathogens maintain the extraordinary polymorphism at vertebrate Major Histocompatibility Complex (MHC) genes via balancing selection has intrigued evolutionary biologists for over half a century, but direct tests remain challenging. Here we examine whether a well-characterized epidemic of Mycoplasmal conjunctivitis resulted in balancing selection on class II MHC in a wild songbird host, the house finch (Carpodacus mexicanus). First, we confirmed the potential for pathogen-mediated balancing selection by experimentally demonstrating that house finches with intermediate to high multi-locus MHC diversity are more resistant to challenge with Mycoplasma gallisepticum. Second, we documented sequence and diversity-based signatures of pathogen-mediated balancing selection at class II MHC in exposed host populations that were absent in unexposed, control populations across an equivalent time period. Multi-locus MHC diversity significantly increased in exposed host populations following the epidemic despite initial compromised diversity levels from a recent introduction bottleneck in the exposed host range. We did not observe equivalent changes in allelic diversity or heterozygosity across eight neutral microsatellite loci, suggesting that the observations reflect selection rather than neutral demographic processes. Our results indicate that a virulent pathogen can exert sufficient balancing selection on class II MHC to rescue compromised levels of genetic variation for host resistance in a recently bottlenecked population. These results provide evidence for Haldane's long-standing hypothesis that pathogens directly contribute to the maintenance of the tremendous levels of genetic variation detected in natural populations of vertebrates

Social Intelligence and Academic Achievement as Predictors of Adolescent Popularity

This study compared the effects of social intelligence and cognitive intelligence, as measured by academic achievement, on adolescent popularity in two school contexts. A distinction was made between sociometric popularity, a measure of acceptance, and perceived popularity, a measure of social dominance. Participants were 512, 14–15 year-old adolescents (56% girls, 44% boys) in vocational and college preparatory schools in Northwestern Europe. Perceived popularity was significantly related to social intelligence, but not to academic achievement, in both contexts. Sociometric popularity was predicted by an interaction between academic achievement and social intelligence, further qualified by school context. Whereas college bound students gained sociometric popularity by excelling both socially and academically, vocational students benefited from doing well either socially or academically, but not in combination. The implications of these findings were discussed

Absence of RIP140 Reveals a Pathway Regulating glut4-Dependent Glucose Uptake in Oxidative Skeletal Muscle through UCP1-Mediated Activation of AMPK

Skeletal muscle constitutes the major site of glucose uptake leading to increased removal of glucose from the circulation in response to insulin. Type 2 diabetes and obesity are often associated with insulin resistance that can be counteracted by exercise or the use of drugs increasing the relative proportion of oxidative fibers. RIP140 is a transcriptional coregulator with a central role in metabolic tissues and we tested the effect of modulating its level of expression on muscle glucose and lipid metabolism in two mice models. Here, we show that although RIP140 protein is expressed at the same level in both oxidative and glycolytic muscles, it inhibits both fatty acid and glucose utilization in a fiber-type dependent manner. In RIP140-null mice, fatty acid utilization increases in the extensor digitorum longus and this is associated with elevated expression of genes implicated in fatty acid binding and transport. In the RIP140-null soleus, depletion of RIP140 leads to increased GLUT4 trafficking and glucose uptake with no change in Akt activity. AMPK phosphorylation/activity is inhibited in the soleus of RIP140 transgenic mice and increased in RIP140-null soleus. This is associated with increased UCP1 expression and mitochondrial uncoupling revealing the existence of a signaling pathway controlling insulin-independent glucose uptake in the soleus of RIP140-null mice. In conclusion, our findings reinforce the participation of RIP140 in the maintenance of energy homeostasis by acting as an inhibitor of energy production and particularly point to RIP140 as a promising therapeutic target in the treatment of insulin resistance

Feasibility study of portable technology for weight loss and HbA1c control in type 2 diabetes

Background The study investigated the feasibility of conducting a future Randomised Controlled Trial (RCT) of a mobile health (mHealth) intervention for weight loss and HbA1c reduction in Type 2 Diabetes Mellitus (T2DM). Methods The intervention was a small wearable mHealth device used over 12 weeks by overweight people with T2DM with the intent to lose weight and reduce their HbA1c level. A 4 week maintenance period using the device followed. The device records physical activity level and information about food consumption, and provides motivational feedback based on energy balance. Twenty-seven participants were randomised to receive no intervention; intervention alone; or intervention plus weekly motivational support. All participants received advice on diet and exercise at the start of the study. Weight and HbA1c levels were recorded at baseline and weeks 6, 12, and 16. Qualitative interviews were conducted with participants who received the intervention to explore their experiences of using the device and involvement in the study including the training received. Results Overall the device was perceived to be well-liked, acceptable, motivational and easy to use by participants. Some logistical changes were required during the feasibility study, including shortening of the study duration and relaxation of participant inclusion criteria. Descriptive statistics of weight and HbA1c data showed promising trends of weight loss and HbA1c reduction in both intervention groups, although this should be interpreted with caution. Conclusions A number of methodological recommendations for a future RCT emerged from the current feasibility study. The mHealth device was acceptable and promising for helping individuals with T2DM to reduce their HbA1c and lose weight. Devices with similar features should be tested further in larger studies which follow these methodological recommendations

Multidisciplinary and multifaceted outpatient management of patients with osteoarthritis: protocol for a randomised, controlled trial

<p>Abstract</p> <p>Background</p> <p>Osteoarthritis (OA) is a prevalent joint disorder with a need for efficient and evidence-based management strategies.</p> <p>Objectives</p> <p>The primary purpose of this study is to compare the effects of a multidisciplinary outpatient clinic, including a brief group-based educational programme, with a traditional individual outpatient clinic for patients with hip, knee, hand or generalized OA. A secondary purpose is to investigate the effects of a telephone follow-up call.</p> <p>Methods</p> <p>This is a pragmatic randomised single-blind controlled study with a total of 400 patients with hip, knee, hand or generalized OA between 40 and 80 years referred to an outpatient rheumatology hospital clinic. The randomisation is stratified according to the diagnostic subgroups. The experimental group is exposed to a multidisciplinary and multifaceted intervention, including a 3.5 hour group-based patient education programme about OA in addition to individual consultations with members of a multidisciplinary team. The control intervention is based on regular care with an individual outpatient consultation with a rheumatologist (treatment as usual). Primary outcomes are patient satisfaction measured at 4 months and cost-effectiveness measured at 12 months. Secondary outcomes are pain and global disease activity measured on a numeric rating scales (NRS), generic and disease specific functioning and disability using Short Form-36 (SF-36) health survey, the Western Ontario and McMaster Universities Osteoarthritis Index 3 (WOMAC), the Australian/Canadian Osteoarthritis Hand Index (AUSCAN), and a patient-generated measure of disability (Patient-Specific Functional scale, PSFS). Global perceived effect of change in health status during the study period is also reported. At 4-month follow-up, patients in both groups will be randomly allocated to a 10-minute telephone call or no follow-up ("treatment as usual"). After additional 8 months (12-month follow-up) the four groups will be compared in a secondary analysis with regard to health outcomes and health care costs.</p> <p>Discussion</p> <p>This trial will provide results on how multidisciplinary and multifaceted management of patients with OA affects health outcomes and health care costs.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN25778426</p