Prediction Analysis and Management Decisions

The dynamic nature of the Apollo Program, with its many complexities, demands tomorrow 1 s answers today. To meet this need and provide decision bases upon which to act, the Apollo Program Control Directorate of NASA Headquarters has under continuous development rigorous prediction analysis techniques necessary to the detection of potential weaknesses before they become critical. This work is presently pointed toward predictions of space vehicle weight and performance as related to schedules, cost, and reliability. The prediction analysis technique described here combines applicable domains of classical statistical methods, relevancy devices, mathematical modeling, management decision criteria, electronic computer usage, hardware trade-off and error analyses. The techniques developed are not a cure-all, but do provide engineering and program managers that data necessary to pin-point critical issues, define courses of action and thereby factually support technical and management judgements

Study of the acoustic signature of UHE neutrino interactions in water and ice

The production of acoustic signals from the interactions of ultra-high energy (UHE) cosmic ray neutrinos in water and ice has been studied. A new computationally fast and efficient method of deriving the signal is presented. This method allows the implementation of up to date parameterisations of acoustic attenuation in sea water and ice that now includes the effects of complex attenuation, where appropriate. The methods presented here have been used to compute and study the properties of the acoustic signals which would be expected from such interactions. A matrix method of parameterising the signals, which includes the expected fluctuations, is also presented. These methods are used to generate the expected signals that would be detected in acoustic UHE neutrino telescopes.Comment: 21 pages and 13 figure

Non-abelian Harmonic Oscillators and Chiral Theories

We show that a large class of physical theories which has been under intensive investigation recently, share the same geometric features in their Hamiltonian formulation. These dynamical systems range from harmonic oscillations to WZW-like models and to the KdV dynamics on $Diff_oS^1$. To the same class belong also the Hamiltonian systems on groups of maps. The common feature of these models are the 'chiral' equations of motion allowing for so-called chiral decomposition of the phase space.Comment: 1

The validity and reliability of the my jump 2 app for measuring the reactive strength index and drop jump performance.

BACKGROUND: This is the first study to independently assess the concurrent validity and reliability of the My Jump 2 app for measuring drop jump performance. It is also the first to evaluate the app's ability to measure the reactive strength index (RSI). METHODS: Fourteen male sport science students (age: 29.5±9.9 years) performed three drop jumps from 20 cm and 40 cm (totaling 84 jumps), assessed via a force platform and the My Jump 2 app. Reported metrics included reactive strength index, jump height, ground contact time, and mean power. Measurements from both devices were compared using the intraclass correlation coefficient (ICC), Pearson product moment correlation coefficient (r), Cronbach's alpha (α), coefficient of variation (CV) and Bland-Altman plots. RESULTS: Near perfect agreement was seen between devices at 20 cm for RSI (ICC=0.95) and contact time (ICC=0.99) and at 40 cm for RSI (ICC=0.98), jump height (ICC=0.96) and contact time (ICC=0.92); with very strong agreement seen at 20 cm for jump height (ICC=0.80). In comparison with the force plate the app showed good validity for RSI (20 cm: r=0.94; 40 cm; r=0.97), jump height (20 cm: r=0.80; 40 cm; r=0.96) and contact time (20 cm=0.96; 40 cm; r=0.98). CONCLUSIONS: The results of the present study show that the My Jump 2 app is a valid and reliable tool for assessing drop jump performance

Measuring velocity of sound with nuclear resonant inelastic x-ray scattering

Nuclear resonant inelastic x-ray scattering is used to measure the projected partial phonon density of states of materials. A relationship is derived between the low-energy part of this frequency distribution function and the sound velocity of materials. Our derivation is valid for harmonic solids with Debye-like low-frequency dynamics. This method of sound velocity determination is applied to elemental, composite, and impurity samples which are representative of a wide variety of both crystalline and noncrystalline materials. Advantages and limitations of this method are elucidated