Elite male Flat jockeys display lower bone density and lower resting metabolic rate than their female counterparts: implications for athlete welfare

To test the hypothesis that daily weight-making is more problematic to health in male compared with female jockeys, we compared the bone-density and resting metabolic rate (RMR) in weight-matched male and female Flat-jockeys. RMR (kcal.kg-1 lean mass) was lower in males compared with females as well as lower bone-density Z-scores at the hip and lumbar spine. Data suggest the lifestyle of male jockeys’ compromise health more severely than females, possibly due to making-weight more frequently

Diffuse HI Disks in Isolated Galaxies

In order to investigate the contribution of diffuse components to their total HI emission, we have obtained high precision HI line flux densities with the 100m Green Bank Telescope for a sample of 100 isolated spiral and irregular galaxies which we have previously observed with the 43m telescope. A comparison of the observed HI line fluxes obtained with the two different telescopes, characterized by half-power beam widths of 9 arcmin and 21 arcmin respectively, exploits a ``beam matching'' technique to yield a statistical determination of the occurrence of diffuse HI components in their disks. A simple model of the HI distribution within a galaxy well describes ~75 % of the sample and accounts for all of the HI line flux density. The remaining galaxies are approximately evenly divided into two categories: ones which appear to possess a significantly more extensive HI distribution than the model predicts, and ones for which the HI distribution is more centrally concentrated than predicted. Examples of both extremes can be found in the literature but little attention has been paid to the centrally concentrated HI systems. Our sample has demonstrated that galaxies do not commonly possess extended regions of low surface brightness HI gas which is not accounted for by our current understanding of the structure of HI disks. Eight HI-rich companions to the target objects are identified, and a set of extragalactic HI line flux density calibrators is presented.Comment: 26 page

Electron spin relaxation of N@C60 in CS2

We examine the temperature dependence of the relaxation times of the molecules N@C60 and N@C70 (which comprise atomic nitrogen trapped within a carbon cage) in liquid CS2 solution. The results are inconsistent with the fluctuating zero field splitting (ZFS) mechanism, which is commonly invoked to explain electron spin relaxation for S > 1/2 spins in liquid solution, and is the mechanism postulated in the literature for these systems. Instead, we find a clear Arrhenius temperature dependence for N@C60, indicating the spin relaxation is driven primarily by an Orbach process. For the asymmetric N@C70 molecule, which has a permanent non-zero ZFS, we resolve an additional relaxation mechanism caused by the rapid reorientation of its ZFS. We also report the longest coherence time (T2) ever observed for a molecular electron spin, being 0.25 ms at 170K.Comment: 6 pages, 6 figures V2: Updated to published versio

Newborns' preference for face-relevant stimuli: effects of contrast polarity

There is currently no agreement as to how specific or general are the mechanisms underlying newborns' face preferences. We address this issue by manipulating the contrast polarity of schematic and naturalistic face-related images and assessing the preferences of newborns. We find that for both schematic and naturalistic face images, the contrast polarity is important. Newborns did not show a preference for an upright face-related image unless it was composed of darker areas around the eyes and mouth. This result is consistent with either sensitivity to the shadowed areas of a face with overhead (natural) illumination and/or to the detection of eye contact

AKT regulates NPM dependent ARF localization and p53mut stability in tumors

Nucleophosmin (NPM) is known to regulate ARF subcellular localization and MDM2 activity in response to oncogenic stress, though the precise mechanism has remained elusive. Here we describe how NPM and ARF associate in the nucleoplasm to form a MDM2 inhibitory complex. We find that oligomerization of NPM drives nucleolar accumulation of ARF. Moreover, the formation of NPM and ARF oligomers antagonizes MDM2 association with the inhibitory complex, leading to activation of MDM2 E3-ligase activity and targeting of p53. We find that AKT phosphorylation of NPM-Ser48 prevents oligomerization that results in nucleoplasmic localization of ARF, constitutive MDM2 inhibition and stabilization of p53. We also show that ARF promotes p53 mutant stability in tumors and suppresses p73 mediated p21 expression and senescence. We demonstrate that AKT and PI3K inhibitors may be effective in treatment of therapeutically resistant tumors with elevated AKT and carrying gain of function mutations in p53. Our results show that the clinical candidate AKT inhibitor MK-2206 promotes ARF nucleolar localization, reduced p53(mut) stability and increased sensitivity to ionizing radiation in a xenograft model of pancreatic cancer. Analysis of human tumors indicates that phospho-S48-NPM may be a useful biomarker for monitoring AKT activity and in vivo efficacy of AKT inhibitor treatment. Critically, we propose that combination therapy involving PI3K-AKT inhibitors would benefit from a patient stratification rationale based on ARF and p53(mut) status

Tuning gastropod locomotion: Modeling the influence of mucus rheology on the cost of crawling

Common gastropods such as snails crawl on a solid substrate by propagating muscular waves of shear stress on a viscoelastic mucus. Producing the mucus accounts for the largest component in the gastropod's energy budget, more than twenty times the amount of mechanical work used in crawling. Using a simple mechanical model, we show that the shear-thinning properties of the mucus favor a decrease in the amount of mucus necessary for crawling, thereby decreasing the overall energetic cost of locomotion.Comment: Corrected typo

An efficient Fredholm method for calculation of highly excited states of billiards

A numerically efficient Fredholm formulation of the billiard problem is presented. The standard solution in the framework of the boundary integral method in terms of a search for roots of a secular determinant is reviewed first. We next reformulate the singularity condition in terms of a flow in the space of an auxiliary one-parameter family of eigenproblems and argue that the eigenvalues and eigenfunctions are analytic functions within a certain domain. Based on this analytic behavior we present a numerical algorithm to compute a range of billiard eigenvalues and associated eigenvectors by only two diagonalizations.Comment: 15 pages, 10 figures; included systematic study of accuracy with 2 new figures, movie to Fig. 4, http://www.quantumchaos.de/Media/0703030media.av

A far UV study of interstellar gas towards HD34078: high excitation H2 and small scale structure - Based on observations performed by the FUSE mission and at the CFHT telescope

To investigate the presence of small scale structure in the spatial distribution of H2 molecules we have undertaken repeated FUSE UV observations of the runaway O9.5V star, HD34078. In this paper we present five spectra obtained between January 2000 and October 2002. These observations reveal an unexpectedly large amount of highly excited H2. Column densities for H2 levels from (v = 0, J = 0) up to (v = 0, J = 11) and for several v = 1 and v = 2 levels are determined. These results are interpreted in the frame of a model involving essentially two components: i) a foreground cloud (unaffected by HD34078) responsible for the H2 (J = 0, 1), CI, CH, CH+ and CO absorptions; ii) a dense layer of gas (n = 10E4 cm-3) close to the O star and strongly illuminated by its UV flux which accounts for the presence of highly excited H2. Our model successfully reproduces the H2 excitation, the CI fine-structure level populations as well as the CH, CH+ and CO column densities. We also examine the time variability of H2 absorption lines tracing each of these two components. From the stability of the J = 0, 1 and 2 damped H2 profiles we infer a 3 sigma upper limit on column density variations Delta(N(H2))/N(H2) of 5% over scales ranging from 5 to 50 AU. This result clearly rules out any pronounced ubiquitous small scale "density" structure of the kind apparently seen in HI. The lines from highly excited gas are also quite stable (equivalent to Delta(N)/N <= 30%) indicating i) that the ambient gas through which HD34078 is moving is relatively uniform and ii) that the gas flow along the shocked layer is not subject to marked instabilitie

Habitat‐dependent occupancy and movement in a migrant songbird highlights the importance of mangroves and forested lagoons in Panama and Colombia

Climate change is predicted to impact tropical mangrove forests due to decreased rainfall, sea‐level rise, and increased seasonality of flooding. Such changes are likely to influence habitat quality for migratory songbirds occupying mangrove wetlands during the tropical dry season. Overwintering habitat quality is known to be associated with fitness in migratory songbirds, yet studies have focused primarily on territorial species. Little is known about the ecology of nonterritorial species that may display more complex movement patterns within and among habitats of differing quality. In this study, we assess within‐season survival and movement at two spatio‐temporal scales of a nonterritorial overwintering bird, the prothonotary warbler (Protonotaria citrea), that depends on mangroves and tropical lowland forests. Specifically, we (a) estimated within‐patch survival and persistence over a six‐week period using radio‐tagged birds in central Panama and (b) modeled abundance and occupancy dynamics at survey points throughout eastern Panama and northern Colombia as the dry season progressed. We found that site persistence was highest in mangroves; however, the probability of survival did not differ among habitats. The probability of warbler occupancy increased with canopy cover, and wet habitats were least likely to experience local extinction as the dry season progressed. We also found that warbler abundance is highest in forests with the tallest canopies. This study is one of the first to demonstrate habitat‐dependent occupancy and movement in a nonterritorial overwintering migrant songbird, and our findings highlight the need to conserve intact, mature mangrove, and lowland forests

Opening up the Quantum Three-Box Problem with Undetectable Measurements

One of the most striking features of quantum mechanics is the profound effect exerted by measurements alone. Sophisticated quantum control is now available in several experimental systems, exposing discrepancies between quantum and classical mechanics whenever measurement induces disturbance of the interrogated system. In practice, such discrepancies may frequently be explained as the back-action required by quantum mechanics adding quantum noise to a classical signal. Here we implement the 'three-box' quantum game of Aharonov and Vaidman in which quantum measurements add no detectable noise to a classical signal, by utilising state-of-the-art control and measurement of the nitrogen vacancy centre in diamond. Quantum and classical mechanics then make contradictory predictions for the same experimental procedure, however classical observers cannot invoke measurement-induced disturbance to explain this discrepancy. We quantify the residual disturbance of our measurements and obtain data that rule out any classical model by > 7.8 standard deviations, allowing us for the first time to exclude the property of macroscopic state-definiteness from our system. Our experiment is then equivalent to a Kochen-Spekker test of quantum non-contextuality that successfully addresses the measurement detectability loophole