Efficacy of Depth Jump Parameters as a Recovery Monitoring Tool

Background: Fatigue monitoring is an important aspect for athletic coaches to monitor the level of readiness of an athlete. Monitoring of an athlete’s fatigue status helps identify the need to adjust one’s training program, identify injury risk, and help attain an athlete’s peak performance when it is most advantageous for them. More research is warranted that examines the effects of a comprehensive set of jump parameters to track recovery from muscle impairing exercise. This study focused on the onset of muscle soreness through eccentric resistance exercise. Purpose: The purpose of this project was to examine the efficacy of force plate GRF-derived data from depth jump (DJ), and peak force (PF) by maximum voluntary isometric contraction tests as a means to track neuromuscular recovery following a bout of eccentric exercise. A secondary aim was to evaluate soreness markers during the recovery phase. Methods: Thirty college aged, recreationally active students participated in this study. This study was a repeated measures design where each subject participated in 5 visits including a familiarization visit, an experimental visit (when the eccentric exercise was performed), and three follow up visits. The second visit included subjects performing the eccentric exercise intervention where they performed a 3 minute workout at 50% intensity. Testing including maximal voluntary isometric contractions MVICs and was done at pre- and post-exercise as well as 24, 48, and 96 h following the exercise session. Testing involved MVICs on the dynamometer (to determine peak force; PF), followed by DJ tests. Also, each subject was asked to complete a visual analog scale (VAS) to determine soreness upon arrival of each visit. All post intervention visits were identical in format except they did not do the exercise intervention. Results: There were no changes in DJ GRF variables nor PF, but there was a significant difference in soreness across the visits, suggesting that the eccentric exercise intervention on the Eccentron succeeded in inducing muscle damage. Conclusion: Data from this study suggest that despite participants experiencing significant soreness in the period that followed the eccentric protocol, there were no changes in ground reaction force parameters from a DJ performance nor in PF variables. Greater impairments to force generating capacities than what were found herein are required from an eccentric exercise intervention to determine whether DJ measures can adequately monitor fatigue characteristics

Generalised Swan modules and the D(2) problem

We give a detailed proof that, for any natural number n, each algebraic two complex over C_n \times C_\infty is realised up to congruence by a geometric complex arising from a presentation for the group.Comment: This is the version published by Algebraic & Geometric Topology on 24 February 200

Array measurements of P velocities in the lower mantle

The extended array at the Tonto Forest Seismological Observatory in central Arizona has been used to measure dT/dΔ of direct P waves from 212 earthquakes in the distance range between 30 and 100°, and these data have been inverted to obtain a velocity model for the lower mantle. Travel times calculated for this model are in good agreement with empirical travel times. The dT/dΔ data from different azimuths and from different focal depths are all in reasonably good agreement with the exception of anomalously large values from earthquakes on the mid-Atlantic ridge. The effect of the core on the measured values of dT/dΔ at distances greater than 90° is shown to be significant, and a correction is made for this effect. A curve fit to the dT/dΔ data contains anomalous regions near the epicentral distances of 34.5, 40.5, 49.5, 59.5, 70.5, and 81.5° which may correspond to increased velocity gradients near the depths of 830, 1000, 1230, 1540, 1910, and 2370 km. PcP times were used to estimate a core radius of 3481 km

OPTIMIZING THE SUSTAINMENT NETWORK FOR EXPEDITIONARY ADVANCED BASE OPERATIONS

The Marine Corps’ Expeditionary Advanced Base Operations (EABO) concept places small, distributed forces within a contested environment to achieve strategic effects. However, current sustainment platforms and infrastructure lack the ability to provide required support in the context of EABO. As such, the Marine Corps must develop a novel resilient and robust distribution network capable of providing responsive sustainment to forces conducting EABO. To solve this problem, we develop a two-stage stochastic mixed integer linear program that seeks to minimize the cost of instantiating and operating a sustainment network across a range of possible in-context scenarios. Among the network’s constraints are demand, cost, capacity, risk, and supply considerations. Of these constraints, demand introduces the most uncertainty. Fluctuations in demand come from a variety of factors to include intensity of conflict, attrition, and other combat dynamics. Through the explicit and judicious modeling of such uncertainty, our model provides solutions that are robust to a wide range of demand scenarios. By implementing our model in a notional operational scenario in the South China Sea, we provide results and insights that ultimately assist the Marine Corps by providing an analytical basis for determining an optimal network comprised of locations, capacities, and prepositioning quantities for sustaining forces conducting EABO in the western Pacific.Outstanding ThesisCaptain, United States Marine CorpsApproved for public release. Distribution is unlimited

Database queries and constraints via lifting problems

Previous work has demonstrated that categories are useful and expressive models for databases. In the present paper we build on that model, showing that certain queries and constraints correspond to lifting problems, as found in modern approaches to algebraic topology. In our formulation, each so-called SPARQL graph pattern query corresponds to a category-theoretic lifting problem, whereby the set of solutions to the query is precisely the set of lifts. We interpret constraints within the same formalism and then investigate some basic properties of queries and constraints. In particular, to any database $\pi$ we can associate a certain derived database \Qry(\pi) of queries on $\pi$. As an application, we explain how giving users access to certain parts of \Qry(\pi), rather than direct access to $\pi$, improves ones ability to manage the impact of schema evolution

The role of matrix cracks and fibre/matrix debonding on the stress transfer between fibre and matrix in a single fibre fragmentation test

The single fibre fragmentation test is commonly used to characterise the fibre/matrix interface. During fragmentation, the stored energy is released resulting in matrix cracking and/or fibre/matrix debonding. Axisymmetric finite element models were formulated to study the impact of matrix cracks and fibre/matrix debonding on the effective stress transfer efficiency (EST) and stress transfer length (STL). At high strains, plastic deformation in the matrix dominated the stress transfer mechanism. The combination of matrix cracking and plasticity reduced the EST and increased STL. For experimental validation, three resins were formulated and the fragmentation of an unsized and uncoupled E-glass fibre examined as a function of matrix properties. Fibre failure was always accompanied by matrix cracking and debonding. With the stiff resin, debonding, transverse matrix cracking and conical crack initiation were observed. With a lower modulus and lower yield strength resin the transverse matrix crack length decreased while that of the conical crack increased. (C) 2011 Elsevier Ltd. All rights reserved

An alternate method for achieving temperature control in the -130 C to 75 C range

Thermal vacuum testing often requires temperature control of chamber shrouds and heat exchangers within the -130 C to 75 C range. There are two conventional methods which are normally employed to achieve control through this intermediate temperature range: (1) single-pass flow where control is achieved by alternately pulsing hot gaseous nitrogen (GN2) and cold LN2 into the feed line to yield the setpoint temperature; and (2) closed-loop circulation where control is achieved by either electrically heating or LN2 cooling the circulating GN2 to yield the setpoint temperature. A third method, using a mass flow ratio controller along with modulating control valves on GN2 and LN2 lines, provides excellent control but equipment for this method is expensive and cost-prohibitive for all but long-term continuous processes. The single-pass method provides marginal control and can result in unexpected overcooling of the test article from even a short pulse of LN2. The closed-loop circulation method provides excellent control but requires an expensive blower capable of operating at elevated pressures and cryogenic temperatures. Where precise control is needed (plus or minus 2 C), single-pass flow systems typically have not provided the precision required, primarily because of overcooling temperature excursions. Where several individual circuits are to be controlled at different temperatures, the use of expensive cryogenic blowers for each circuit is also cost-prohibitive, especially for short duration of one-of-a-kind tests. At JPL, a variant of the single-pass method was developed that was shown to provide precise temperature control in the -130 C to 75 C range while exhibiting minimal setpoint overshoot during temperature transitions. This alternate method uses a commercially available temperature controller along with a GN2/LN2 mixer to dampen the amplitude of cold temperature spikes caused by LN2 pulsing. The design of the GN2/LN2 mixer, the overall control system configuration, the operational procedure, and the prototype system test results are described

Epicentral confidence regions of nuclear test events at teleseismic distances

The accurate location of seismic events is a basic discriminant for underground nuclear test monitoring (Bolt, 1976; Dahlman and Israelson, 1977; Blandford, 1982). Of particular interest are determining epicentral confidence regions and providing constraints on estimated focal depths. In this study, only routine teleseismic P travel-time data are used, as provided by worldwide stations reporting to the International Seismological Centre (ISC). This lessens the need to model the effects of crustal and shallow-mantle velocity variations, as is necessary with seismographic networks operating at regional distances (Blandford, 1981; Evernden et al., 1986)

Source parameters of moderate size earthquakes and the importance of receiver crustal structure in interpreting observations of local earthquakes

Broadband observations of three central California earthquakes as recorded on opposite sides of the San Andreas fault zone are studied. The earthquake mechanisms are of the strike-slip type occurring along the fault at epicentral distances between 15 and 30 km. The seismograms obtained at the two sites are distinctly dissimilar in both amplitude and wave shape even though they are at roughly the same azimuth. We suppose that the earthquake excitation is identical for the two sites and that the differences in seismograms are caused by the receiver structure. The problem is idealized by assuming that the first 10 sec of each record can be modeled synthetically with a point shear dislocation embedded in a half-space with a two-layer upper-crustal model appropriate for each site. The results determined by matching the observations indicate that the durations for these events with M_L = 4 to 5 are about 0.3 to 0.6 sec. Furthermore, the results demonstrate that accurate estimate of source parameters can only be accomplished after a detailed appreciation of crustal structure