Measuring physical performance via self-report in healthy young adults

Discrepancies exist in literature as to what extent self-reporting can replace performance-based testing. To answer this question, self-reports and performance tests should measure identical constructs. Previous studies did not measure identical constructs. The objective of our study was to investigate to what extent self-reporting can replace performance-based testing. Seventy-two healthy subjects were tested. The constructs of the self-reports and the performance tests covered the same components to enable a comparison of self-reports and performance test results. Three different self-reports and a performance test were used to measure physical performance. Additionally, rating of perceived exertion was measured after the subjects lifted a reference weight to predict maximal lifting performance. The controls were age, gender, educational level, subject's participation in fitness, availability of reference data, motivation, attitude, general self-efficacy, and mood. Results showed that all lifting tasks could be predicted, though not solely via self-reporting. A prediction of the performance test results with a margin of +/-5 kg of error could be made for at least 79% of the subjects, via gender, self-reporting, and subject's participation in fitness. Self-reporting may not replace performance testing, although performance testing can be predicted with a margin of error of +/- 5 kg for at least 79% of the healthy subject

Single fibre action potentials in skeletal muscle related to recording distances

Single muscle fibre action potentials (SFAPs) are considered to be functions of a bioelectrical source and electrical conductivity parameters of the medium. In most model studies SFAPs are computed as a convolution of the bioelectrical source with a transfer function. Calculated peak-to-peak amplitudes of SFAPs decrease with increasing recording distances. In this paper an experimental validation of model results is presented. Experiments were carried out on the m. extensor digitorum longus (EDL) of the rat. Using a method including fluorescent labelling of the active fibre, the distance between the active fibre and the recording electrode was derived. With another method, the decline of the peak-to-peak amplitude of SFAPs detected along a multi-electrode was obtained. With both experimental methods, in general peak-to-peak amplitudes of SFAPs decreased with increasing recording distances, as was found in model results with present volume conduction theory. However, this behaviour was not found in all experiments. The rate of decline of the peak-to-peak amplitudes with recording distance was always less than in models

Modelling the growth of preruminant calves

The emphasis in meat production has shifted from maximizing production volume to the efficient production of lean meat. Body composition can to a large extent be manipulated by nutritional means. It does, however, require integrated knowledge of protein and energy metabolism. Two experiments were performed with male, preruminant calves, to quantify the relationship between nutrient intake (protein, energy) and the rate of gain of live weight, protein and fat in the live weight range 80 to 240 kg. These experiments showed that calves in this weight range respond to increased protein intake by increasing their protein and fat deposition rates. The utilization of digested protein decreased from 60% at low protein intake levels to 35% at high protein intake levels. Extra protein-free energy results mainly in extra fat deposition, but also increases protein deposition rate, even at low protein intakes. Subsequently, the results of these experiments were used for the construction of a dynamic, mechanistic growth simulation model. The model predicts rates of gain of body weight, body fat and body protein (in several tissues) from nutrient intake. It can also be used to predict amino acid requirements. Protein and fat accretion rates obtained in independent experiments could be simulated satisfactorily. Additional measurements, performed in the experiments showed that the rate of muscle protein degradation, measured by the urinary excretion of 3-methylhistidine, increased with increasing protein deposition rates. Furthermore, it was shown that plasma levels of triiodothyronine strongly respond to increased intake of protein-free energy but hardly to increased protein intakes. In contrast, plasma levels of thyroxine and insulin-like growth factor-1 were increased by increasing protein intake, but unaffected by increased protein-free energy intake levels

The hydration of divalent cations in aqueous solution : an x-ray investigation with isomorphous replacement

The x-ray diffraction patterns of M solns. of the nitrates of Co2+, Ni2 +, Zn2+, Mg2+, Cd2+, and Ca2+ were recorded with an Enraf-Nonius liq . jet diffraction camera. These cations were paired into 4 isomorphous groups based on the similarities of the cation-water distances in their cryst. hydrates. A theoretical expression was derived relating the electron distribution function to the difference in the intensities diffracted by a pair of isomorphous solns., and this function was obtained by calcg. the Fourier transform, using the measured intensities. The resulting electron distribution function exhibited a peak near 2 g, ascribed to the primary hydration layer, and a 2nd, less clear-cut, peak near 4 .ANG., attributed to the secondary hydration layer. Least-squares fits of these peaks yielded primary coordination nos. and cation water distances at 25°, and a secondary coordination no. of 12 ± 2. Cation-water distances were also obtained when minor deviations from isomorphism were taken into account

Spatially resolved ultrafast precessional magnetization reversal

Spatially resolved measurements of quasi-ballistic precessional magnetic switching in a microstructure are presented. Crossing current wires allow detailed study of the precessional switching induced by coincident longitudinal and transverse magnetic field pulses. Though the response is initially spatially uniform, dephasing occurs leading to nonuniformity and transient demagnetization. This nonuniformity comes in spite of a novel method for suppression of end domains in remanence. The results have implications for the reliability of ballistic precessional switching in magnetic devices.Comment: 17 pages (including 4 figures), submitted to Phys. Rev. Let

Detector-Agnostic Phase-Space Distributions

The representation of quantum states via phase-space functions constitutes an intuitive technique to characterize light. However, the reconstruction of such distributions is challenging as it demands specific types of detectors and detailed models thereof to account for their particular properties and imperfections. To overcome these obstacles, we derive and implement a measurement scheme that enables a reconstruction of phase-space distributions for arbitrary states whose functionality does not depend on the knowledge of the detectors, thus defining the notion of detector-agnostic phase-space distributions. Our theory presents a generalization of well-known phase-space quasiprobability distributions, such as the Wigner function. We implement our measurement protocol, using state-of-the-art transition-edge sensors without performing a detector characterization. Based on our approach, we reveal the characteristic features of heralded single- and two-photon states in phase space and certify their nonclassicality with high statistical significance

Tomography of photon-number resolving continuous-output detectors

We report a comprehensive approach to analysing continuous-output photon detectors. We employ principal component analysis to maximise the information extracted, followed by a novel noise-tolerant parameterised approach to the tomography of PNRDs. We further propose a measure for rigorously quantifying a detector's photon-number-resolving capability. Our approach applies to all detectors with continuous-output signals. We illustrate our methods by applying them to experimental data obtained from a transition-edge sensor (TES) detector.Comment: 5 pages, 3 figures, also includes supplementary informatio