Trapped and marginally trapped surfaces in Weyl-distorted Schwarzschild solutions

To better understand the allowed range of black hole geometries, we study Weyl-distorted Schwarzschild solutions. They always contain trapped surfaces, a singularity and an isolated horizon and so should be understood to be (geometric) black holes. However we show that for large distortions the isolated horizon is neither a future outer trapping horizon (FOTH) nor even a marginally trapped surface: slices of the horizon cannot be infinitesimally deformed into (outer) trapped surfaces. We consider the implications of this result for popular quasilocal definitions of black holes.Comment: The results are unchanged but this version supersedes that published in CQG. The major change is a rewriting of Section 3.1 to improve clarity and correct an error in the general expression for V(r,\theta). Several minor errors are also fixed - most significantly an incorrect statement made in the introduction about the extent of the outer prison in Vaidya. 17 pages, 2 figure

Differences in mitochondrial efficiency explain individual variation in growth performance

The physiological causes of intraspecific differences in fitness components such as growth rate are currently a source of debate. It has been suggested that differences in energy metabolism may drive variation in growth, but it remains unclear whether covariation between growth rates and energy metabolism is: (i) a result of certain individuals acquiring and consequently allocating more resources to growth, and/or is (ii) determined by variation in the efficiency with which those resources are transformed into growth. Studies of individually housed animals under standardized nutritional conditions can help shed light on this debate. Here we quantify individual variation in metabolic efficiency in terms of the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by liver and muscle mitochondria and examine its effects, both on the rate of protein synthesis within these tissues and on the rate of whole-body growth of individually fed juvenile brown trout (Salmo trutta) receiving either a high or low food ration. As expected, fish on the high ration on average gained more in body mass and protein content than those maintained on the low ration. Yet, growth performance varied more than 10-fold among individuals on the same ration, resulting in some fish on low rations growing faster than others on the high ration. This variation in growth for a given ration was related to individual differences in mitochondrial properties: a high whole-body growth performance was associated with high mitochondrial efficiency of ATP production in the liver. Our results show for the first time, to our knowledge, that among-individual variation in the efficiency with which substrates are converted into ATP can help explain marked variation in growth performance, independent of food intake. This study highlights the existence of inter-individual differences in mitochondrial efficiency and its potential importance in explaining intraspecific variation in whole-animal performance

Differences in mitochondrial efficiency explain individual variation in growth performance

The physiological causes of intraspecific differences in fitness components such as growth rate are currently a source of debate. It has been suggested that differences in energy metabolism may drive variation in growth, but it remains unclear whether covariation between growth rates and energy metabolism is: (i) a result of certain individuals acquiring and consequently allocating more resources to growth, and/or is (ii) determined by variation in the efficiency with which those resources are transformed into growth. Studies of individually housed animals under standardized nutritional conditions can help shed light on this debate. Here we quantify individual variation in metabolic efficiency in terms of the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by liver and muscle mitochondria and examine its effects, both on the rate of protein synthesis within these tissues and on the rate of whole-body growth of individually fed juvenile brown trout (Salmo trutta) receiving either a high or low food ration. As expected, fish on the high ration on average gained more in body mass and protein content than those maintained on the low ration. Yet, growth performance varied more than 10-fold among individuals on the same ration, resulting in some fish on low rations growing faster than others on the high ration. This variation in growth for a given ration was related to individual differences in mitochondrial properties: a high whole-body growth performance was associated with high mitochondrial efficiency of ATP production in the liver. Our results show for the first time, to our knowledge, that among-individual variation in the efficiency with which substrates are converted into ATP can help explain marked variation in growth performance, independent of food intake. This study highlights the existence of inter-individual differences in mitochondrial efficiency and its potential importance in explaining intraspecific variation in whole-animal performance

Validation of the doubly labeled water method using off-axis integrated cavity output spectroscopy and isotope ratio mass spectrometry

This work was supported by an NIH Small Business Innovation (SBIR) research Grant (R44 DK093362), as well as support from the Colorado Nutrition and Obesity Research Center (P30 DK048520) and the Colorado Clinical and Translational Science Institute (UL1 RR025780). Dr. Melanson is also supported by resources from the Geriatric Research, Education, and Clinical Center at the Denver VA Medical Center.Peer reviewedPostprin

The feasibility of using pedometers and brief advice to increase activity in sedentary older women:a pilot study

Background: People over the age of 70 carry the greatest burden of chronic disease, disability and health care use. Participation in physical activity is crucial for health, and walking accounts for much of the physical activity undertaken by sedentary individuals. Pedometers are a useful motivational tool to encourage increased walking and they are cheap and easy to use. The aim of this pilot study was to evaluate the feasibility of the use of pedometers plus a theory-based intervention to assist sedentary older women to accumulate increasing amounts of physical activity, mainly through walking. Methods: Female participants over the age of 70 were recruited from primary care and randomised to receive either pedometer plus a theory-based intervention or a theory-based intervention alone. The theory-based intervention consisted of motivational techniques, goal-setting, barrier identification and self-monitoring with pedometers and daily diaries. The pedometer group were further randomised to one of three target groups: a 10%, 15% or 20% monthly increase in step count to assess the achievability and acceptability of a range of targets. The primary outcome was change in daily activity levels measured by accelerometry. Secondary outcome measures were lower limb function, health related quality of life, anxiety and depression. Results: 54 participants were recruited into the study, with an average age of 76. There were 9 drop outs, 45 completing the study. All participants in the pedometer group found the pedometers easy to use and there was good compliance with diary keeping (96% in the pedometer group and 83% in the theory-based intervention alone group). There was a strong correlation (0.78) between accelerometry and pedometer step counts i.e. indicating that walking was the main physical activity amongst participants. There was a greater increase in activity (accelerometry) amongst those in the 20% target pedometer group compared to the other groups, although not reaching statistical significance (p = 0.192). Conclusion: We have demonstrated that it is feasible to use pedometers and provide theory-based advice to community dwelling sedentary older women to increase physical activity levels and a larger study is planned to investigate this further.Publisher PDFPeer reviewe

Search for R-parity Violating Supersymmetry in Dimuon and Four-Jets Channel

We present results of a search for R-parity-violating decay of the neutralino chi_1^0, taken to be the Lightest Supersymmetric Particle. It is assumed that this decay proceeds through one of the lepton-number violating couplings lambda-prime_2jk (j=1,2; k=1,2,3). This search is based on 77.5 pb-1 of data, collected by the D0 experiment at the Fermilab Tevatron in ppbar collisions at a center of mass energy of 1.8 TeV in 1992-1995.Comment: 10 pages, 3 figure

A search for W bb and W Higgs production in ppbar collisions at sqrt(s)=1.96 TeV

We present a search for W b \bar{b} production in p \bar{p} collisions at sqrt{s}=1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb-1 of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on W b \bar{b}$production of 6.6 pb for b quarks with transverse momenta p_T^b > 20 GeV and b \bar{b} separation in pseudorapidity-azimuth space Delta R_bb > 0.75. Restricting the search to optimized b \bar{b} mass intervals provides upper limits on$WH$production of 9.0$-$12.2 pb, for Higgs-boson masses of 105$-$135 GeV.Comment: 7 pages, 4 figures, 1 table, submitted to Physical Review Letter

Shadowing in Inelastic Scattering of Muons on Carbon, Calcium and Lead at Low XBj

Nuclear shadowing is observed in the per-nucleon cross-sections of positive muons on carbon, calcium and lead as compared to deuterium. The data were taken by Fermilab experiment E665 using inelastically scattered muons of mean incident momentum 470 GeV/c. Cross-section ratios are presented in the kinematic region 0.0001 < XBj <0.56 and 0.1 < Q**2 < 80 GeVc. The data are consistent with no significant nu or Q**2 dependence at fixed XBj. As XBj decreases, the size of the shadowing effect, as well as its A dependence, are found to approach the corresponding measurements in photoproduction.Comment: 22 pages, incl. 6 figures, to be published in Z. Phys.

A Quasi-Model-Independent Search for New Physics at Large Transverse Momentum

We apply a quasi-model-independent strategy ("Sleuth") to search for new high p_T physics in approximately 100 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV collected by the DZero experiment during 1992-1996 at the Fermilab Tevatron. Over thirty-two e mu X, W+jets-like, Z+jets-like, and 3(lepton/photon)X exclusive final states are systematically analyzed for hints of physics beyond the standard model. Simultaneous sensitivity to a variety of models predicting new phenomena at the electroweak scale is demonstrated by testing the method on a particular signature in each set of final states. No evidence of new high p_T physics is observed in the course of this search, and we find that 89% of an ensemble of hypothetical similar experimental runs would have produced a final state with a candidate signal more interesting than the most interesting observed in these data.Comment: 28 pages, 17 figures. Submitted to Physical Review