Reliability of a high-intensity endurance cycling test.

This study assessed the reproducibility of performance and selected metabolic variables during a variable high-intensity endurance cycling test. 8 trained male cyclists (age: 35.9 ± 7.7 years, maximal oxygen uptake: 54.3 ± 3.9 mL·kg - 1·min - 1) completed 4 high-intensity cycling tests, performed in consecutive weeks. The protocol comprised: 20 min of progressive incremental exercise, where the power output was increased by 5% maximal workload (Wmax) every 5 min from 70% Wmax to 85% Wmax; ten 90 s bouts at 90% Wmax, separated by 180 s at 55% Wmax; 90% Wmax until volitional exhaustion. Blood samples were drawn and heart rate was monitored throughout the protocol. There was no significant order effect between trials for time to exhaustion (mean: 4 113.0 ± 60.8 s) or total distance covered (mean: 4 6126.2 ± 1 968.7 m). Total time to exhaustion and total distance covered showed very high reliability with a mean coefficient of variation (CV) of 1.6% (95% Confidence Intervals (CI) 0.0 ± 124.3 s) and CV of 2.2% (95% CI 0.0 ± 1904.9 m), respectively. Variability in plasma glucose concentrations across the time points was very small (CV 0.46-4.3%, mean 95% CI 0.0 ± 0.33 to 0.0 ± 0.94 mmol·L - 1). Plasma lactate concentrations showed no test order effect. The reliability of performance and metabolic variables makes this protocol a valid test to evaluate nutritional interventions in endurance cycling

Characterization of the Noise in Secondary Ion Mass Spectrometry Depth Profiles

The noise in the depth profiles of secondary ion mass spectrometry (SIMS) is studied using different samples under various experimental conditions. Despite the noise contributions from various parts of the dynamic SIMS process, its overall character agrees very well with the Poissonian rather than the Gaussian distribution in all circumstances. The Poissonian relation between the measured mean-square error (MSE) and mean can be used to describe our data in the range of four orders. The departure from this relation at high counts is analyzed and found to be due to the saturation of the channeltron used. Once saturated, the detector was found to exhibit hysteresis between rising and falling input flux and output counts.Comment: 14 pages, 4 postscript figures, to appear on J. Appl. Phy

The Gravitational Lensing in the QSO 1208+10 from the Proximity Effect in its Lyman alpha Forest

The quasar Q1208+1011 (z_{em}=3.8) is the second highest redshift double quasar ever detected. Several indications point toward it being a gravitational lensed system, although a definitive proof is still lacking. We present new evidence of its lensed nature based on the weakness of the ``proximity effect'' measured in the high resolution Lyman absorption spectrum of the QSO. A luminosity amplification as large as 22 has been derived from this analysis. Indications on the redshift of the lensing galaxy can be obtained from the analysis of the intervening heavy element absorption systems discovered in the QSO high resolution spectrum. On statistical and dynamical grounds a MgII system present at z=1.13 appears as the most likely candidate for the lensing galaxy. We compare the observed parameters with a simple isothermal model for the lens to derive the properties of the lensing galaxy. The resulting magnification factor is smaller, although marginally consistent with that derived by the analysis of the proximity effect.Comment: 11 pages, 2 Postscript figures, ApJ in pres

Ionizing radiation fluctuations and large-scale structure in the Lyman-alpha forest

We investigate the large-scale inhomogeneities of the hydrogen ionizing radiation field in the Universe at redshift z=3. Using a raytracing algorithm, we simulate a model in which quasars are the dominant sources of radiation. We make use of large scale N-body simulations of a LambdaCDM universe, and include such effects as finite quasar lifetimes and output on the lightcone, which affects the shape of quasar light echoes. We create Lya forest spectra that would be generated in the presence of such a fluctuating radiation field, finding that the power spectrum of the Lya forest can be suppressed by as much as 15 % for modes with k=0.05-1 Mpc/h. This relatively small effect may have consequences for high precision measurements of the Lya power spectrum on larger scales than have yet been published. We also investigate another radiation field probe, the cross-correlation of quasar positions and the Lya forest. For both quasar lifetimes which we simulate (10^7 yr and 10^8 yr), we expect to see a strong decrease in the Lya absorption close to other quasars (the ``foreground'' proximity effect). We then use data from the Sloan Digital Sky Survey First Data Release to make an observational determination of this statistic. We find no sign of our predicted lack of absorption, but instead increased absorption close to quasars. If the bursts of radiation from quasars last on average < 10^6 yr, then we would not expect to be able to see the foreground effect. However, the strength of the absorption itself seems to be indicative of rare objects, and hence much longer total times of emission per quasar. Variability of quasars in bursts with timescales > 10^4yr and < 10^6 yr could reconcile these two facts.Comment: Submitted to ApJ, 21 pages, 17 postscript figures, emulateapj.st

Spacecraft-plasma interaction codes: NASCAP/GEO, NASCAP/LEO, POLAR, DynaPAC, and EPSAT

Development of a computer code to simulate interactions between the surfaces of a geometrically complex spacecraft and the space plasma environment involves: (1) defining the relevant physical phenomena and formulating them in appropriate levels of approximation; (2) defining a representation for the 3-D space external to the spacecraft and a means for defining the spacecraft surface geometry and embedding it in the surrounding space; (3) packaging the code so that it is easy and practical to use, interpret, and present the results; and (4) validating the code by continual comparison with theoretical models, ground test data, and spaceflight experiments. The physical content, geometrical capabilities, and application of five S-CUBED developed spacecraft plasma interaction codes are discussed. The NASA Charging Analyzer Program/geosynchronous earth orbit (NASCAP/GEO) is used to illustrate the role of electrostatic barrier formation in daylight spacecraft charging. NASCAP/low Earth orbit (LEO) applications to the CHARGE-2 and Space Power Experiment Aboard Rockets (SPEAR)-1 rocket payloads are shown. DynaPAC application to the SPEAR-2 rocket payloads is described. Environment Power System Analysis Tool (EPSAT) is illustrated by application to Tethered Satellite System 1 (TSS-1), SPEAR-3, and Sundance. A detailed description and application of the Potentials of Large Objects in the Auroral Region (POLAR) Code are presented

Three-dimensional calculation of shuttle charging in polar orbit

The charged particles environment in polar orbit can be of sufficient intensity to cause spacecraft charging. In order to gain a quantitative understanding of such effects, the Air Force is developing POLAR, a computer code which simulates in three dimensions the electrical interaction of large space vehicles with the polar ionospheric plasma. It models the physical processes of wake generation, ambient ion collection, precipitating auroral electron fluxes, and surface interactions, including secondary electron generation and backscattering, which lead to vehicle charging. These processes may be followed dynamically on a subsecond timescale so that the rapid passage through intense auroral arcs can be simulated. POLAR models the ambient plasma as isotropic Maxwellian electrons and ions (0+, H+), and allows for simultaneous precipitation of power-law, energetic Maxwellian, and accelerated Gaussian distributions of electrons. Magnetic field effects will be modeled in POLAR but are currently ignored

Polar orbit electrostatic charging of objects in shuttle wake

A survey of DMSP data has uncovered several cases where precipitating auroral electron fluxes are both sufficiently intense and energetic to charge spacecraft materials such as teflon to very large potentials in the absence of ambient ion currents. Analytical bounds are provided which show that these measured environments can cause surface potentials in excess of several hundred volts to develop on objects in the orbiter wake for particular vehicle orientations

Spin-one ferromagnets with single-ion anisotropy in a perpendicular external field

In this paper, the conventional Holstein-Primakoff method is generalized with the help of the characteristic angle transformation [Lei Zhou and Ruibao Tao, J. Phys. A {\bf 27} 5599 (1994)] for the spin-one magnetic systems with single-ion anisotropies. We find that the weakness of the conventional method for such systems can be overcome by the new approach. Two models will be discussed to illuminate the main idea, which are the ``easy-plane" and the ``easy-axis" spin-one ferromagnet, respectively. Comparisons show that the current approach can give reasonable ground state properties for the magnetic system with ``easy-plane" anisotropy though the conventional method never can, and can give a better representation than the conventional one for the magnetic system with ``easy-axis" anisotropy though the latter is usually believed to be a good approximation in such case. Study of the easy-plane model shows that there is a phase transition induced by the external field, and the low-temperature specific heat may have a peak as the field reaches the critical value.Comment: Using LaTex. To be published in the September 1 issue of Physical Review B (1996). Email address: [email protected]

“We could end up in a lot of trouble” Teachers’ communications with young children about mental health

Purpose – Stigma towards people with mental health problems is a significant problem and appears trenchant despite recent anti-stigma campaigns. Attitudes develop in young children, and may be stronger and less malleable in adolescence. Early intervention may be important for mental health education and stigma prevention. Theory, evidence and practical considerations suggest that teachers’ involvement is key. By exploring communication about mental health between teachers and young children, it will be possible to elaborate how stigma develops and may be ameliorated. This study explored teachers’ accounts of this communication and the factors that influence it. Methodology – Semi-structured interviews with fifteen primary school teachers were transcribed and analysed using a grounded theory approach. Findings – Discussions about mental health were largely absent from the classroom, due to teachers’ anxiety. Teachers felt the need to protect children from exposure to people with mental health problems and even from information about the topic, believed they lacked the necessary expertise, worried that such discussions were outside their remit, and were anxious about parents’ reactions. Originality/Value – This was the first study to interview teachers on this topic and suggests that a significant opportunity to address stigma is being missed. Teachers’ silence may reinforce that mental health problems are taboo, and prevent children from developing knowledge and a language to talk about mental health. The inclusion of teachers in early mental health education is more sustainable and could promote more inclusive attitudes, especially if supported by educational policy and curriculum. Keywords - school, young children, teachers, mental health education, stigma prevention, policy, grounded theory Article Classification – Research Pape