USING THE ABSORBED POWER METHOD TO EVALUATE EFFECTIVENES OF SELECTED SEAT CUSHIONS DURING MANUAL WHEELCHAIR PROPULSION

Although wheelchair users are constantly subjected to oscillatory and shock vibrations not much research has been conducted to assess the whole-body vibrations experienced by wheelchair users. Studies that have been published have only involved the testing of manual wheelchairs not interventions such as suspension or seating systems.The purpose of this study was to determine if selected wheelchair cushions reduce the amount of harmful whole-body vibrations transferred to wheelchair users and, if the absorbed power method a good measure of evaluating the whole-body vibrations.Thirty-two participants, who use a wheelchair as their primary mode of mobility, partook in this study. Four of the most commonly prescribed wheelchair cushions were selected. Participants were asked to propel their wheelchair over a simulated activities of daily living (ADL) obstacle course while acceleration and force data was collected.A repeated measures ANOVA showed no significant differences between the different cushions for the total averaged absorbed power (p = .190), the 50 mm curb drop (p = .234), or the rumble strip (p = .143). A repeated measures ANOVA for the peak curb drop absorbed power revealed a significant difference in the cushions (p = .043).The cushions that appeared to perform the best in this testing appear to be the Invacare Pindot and the Varilite Solo. Not only did those cushions appear to have the lowest values much of the time but did not display the highest values. Absorbed power appears to be just as effective at determining the effects of vibrations in the time domain as the prescribed methods of the ISO 2631 standard

Religion and Right in the Philosophia Christriana of Erasmus from Rotterdam

Although the works of the great humanist, Erasmus, have had a profound effect upon modern discussions of social questions, his attempt to formulate a Christian theory of justice has been almost completely ignored. In this Article, the author examines Erasmus\u27s Philosophia Christiana and discusses the elements of legal theology which it contains

Investigation of issues related to the revision of ISO 10819

This study has three main goals. The first is to evaluate a proposed change to the input spectra for the ISO 10819 antivibration glove tests. Secondly, this study investigates the effect of palm adapter geometry on linear transmissibility and mean corrected transmissibility values. Finally, the effect of test subject training is discussed and supporting data is shown; 30 rigid acrylic adapters were designed, fabricated, and tested. All adapters fell into one of four categories. Category 1 adapters passed the acceptability criteria. Category 2 adapters failed in the low frequency (16--40 Hz). Category 3 adapters failed in the high frequencies (1000--1600 Hz). Category 4 adapters failed in multiple frequency bands. Four category 1 adapters, one category 3 adapter, and one category 4 adapter were chosen for further testing; Mean corrected transmissibility tests were performed for these 6 adapters according to the procedure defined in International Standards Organization\u27s publication, ISO 10819:1996. 3 test subjects, and 3 different commercially available antivibration gloves were used. (Abstract shortened by UMI.)

Development of seat shock isolation systems

A numerical model has been created to predict the behavior of seat shock isolation systems exposed to mine blast loaDing The model is a two dimensional, five degree-of-freedom, rigid body, mass-spring-damper approximation of the seat system and human occupant. The outputs of the model are the positions, velocities, and accelerations of the system masses, the forces of the connecting elements, such as the seat cushion force, the load limiter force, the spinal force, and the Dynamic Response Index (DRI) based on the pelvic z-axis acceleration. The model has been calibrated with drop tower test data collected by the Army Research Laboratory in Aberdeen, Maryland. The model and test results agree within 6% for z-axis acceleration, spine load, and DRI; Two conceptual seat shock isolation systems have been designed using the numerical model, and their components have been assembled and partially tested in the UNLV laboratory. Both designs use air-pneumatic seat cushion technology. For force limiting, one design uses coil rope spring isolators and the other uses an 8896-N (2000-lbf) honeycomb panel force limiter. Both designs are sized to fit in current U.S. military vehicle envelopes. The numerical model predicts the following performance indicators when the seat designs are exposed to a peak acceleration input of 395 g\u27s with a duration of 5 ms, which is typical of mine blast exposure levels. The following results were obtained: (a) design with honeycomb force limiter - peak z-axis pelvic acceleration was 191 m/s2, spine load was 5344 N, and Dynamic Response Index was 13.1 and (b) design with cable rope spring - peak z-axis pelvic acceleration was 179.2 m/s2, spine load was 5368 N, and Dynamic Response Index was 13.1. These levels are acceptable according to Army and NATO recommendations for the survivability of seated crewmembers exposed to a mine blast

A Flux-Scaling Scenario for High-Scale Moduli Stabilization in String Theory

Tree-level moduli stabilization via geometric and non-geometric fluxes in type IIB orientifolds on Calabi-Yau manifolds is investigated. The focus is on stable non-supersymmetric minima, where all moduli are fixed except for some massless axions. The scenario includes the purely axionic orientifold-odd moduli. A set of vacua allowing for parametric control over the moduli vacuum expectation values and their masses is presented, featuring a specific scaling with the fluxes. Uplift mechanisms and supersymmetry breaking soft masses on MSSM-like D7-branes are discussed as well. This scenario provides a complete effective framework for realizing the idea of F-term axion monodromy inflation in string theory. It is argued that, with all masses close to the Planck and GUT scales, one is confronted with working at the threshold of controlling all mass hierarchies.Comment: 74 pages, 3 figure

Energy autonomy in residential buildings: a techno-economic modelbased analysis of the scale effects

An increasingly decentralized energy supply structure alongside economic incentives for increasing the level of self-generation and –consumption are encouraging (higher levels of) energy autonomy. Previous work in this area has focused on the technical and economic aspects of energy autonomy at distinct scales, from individual buildings, through neighbourhoods to districts. This paper employs a mixed integer linear program (MILP) to assess the effects of aggregation across these scales on the economics of energy autonomy in residential buildings. The model minimizes total energy system costs over the lifetime of the energy system, including micro-CHP, PV, thermal and electrical storage, and boilers, at five distinct scales and for nine demand cases. It is subject to several constraints, amongst other things the degree of electrical self-sufficiency. The results indicate a shift in the economically optimal level of electrical self-sufficiency with scale, which in Single Family Households (SFHs) means from around 30% at the individual building level to almost 100% in districts of 1000 SFH households. Above around 560 households it could be economically advantageous to make a district of residential buildings electrically self-sufficient. In addition, a marginal increase in electrical selfsufficiency is significantly more expensive at lower aggregation scales (i.e. single buildings) compared to the scale of neighbourhoods and districts. The level of interaction with the electrical distribution network increases with increasing electrical self-sufficiency before then decreasing at very high (above 70%) levels. Future work should focus on a richer socioeconomic differentiation, considering other sectors and technologies, incorporating demand side options and analysing the effects on the overarching energy system

A Delocalized Proton-Binding Site within a Membrane Protein

AbstractThe role of protein-bound water molecules in protein function and catalysis is an emerging topic. Here, we studied the solvation of an excess proton by protein-bound water molecules and the contribution of the surrounding amino acid residues at the proton release site of the membrane protein bacteriorhodopsin. It hosts an excess proton within a protein-bound water cluster, which is hydrogen bonded to several surrounding amino acids. Indicative of delocalization is a broad continuum absorbance experimentally observed by time-resolved Fourier transform infrared spectroscopy. In combination with site-directed mutagenesis, the involvement of several amino acids (especially Glu-194 and Glu-204) in the delocalization was elaborated. Details regarding the contributions of the glutamates and water molecules to the delocalization mode in biomolecular simulations are controversial. We carried out quantum mechanics/molecular mechanics (QM/MM) self-consistent charge density functional tight-binding simulations for all amino acids that have been experimentally shown to be involved in solvation of the excess proton, and systematically investigated the influence of the quantum box size. We compared calculated theoretical infrared spectra with experimental ones as a measure for the correct description of excess proton delocalization. A continuum absorbance can only be observed for small quantum boxes containing few amino acids and/or water molecules. Larger quantum boxes, including all experimentally shown involved amino acids, resulted in narrow absorbance bands, indicating protonation of a single binding site in contradiction to experimental results. We conclude that small quantum boxes seem to reproduce representative extreme cases of proton delocalization modes: proton delocalization only on water molecules or only between Glu-194 and Glu-204. Extending the experimental spectral region to lower wave numbers, a water-delocalized proton reproduces the observed continuum absorbance better than a glutamate-shared delocalized proton. However, a full agreement between QM simulations and experimental results on the delocalized excess proton will require a larger quantum box as well as more sophisticated QM/MM methods

Towards Mapping-Based Document Retrieval in Heterogeneous Digital Libraries

In many scientific domains, researchers depend on a timely and efficient access to available publications in their particular area. The increasing availability of publications in electronic form via digital libraries is a reaction to this need. A remaining problem is the fact that the pool of all available publications is distributed between different libraries. In order to increase the availability of information, these different libraries should be linked in such a way, that all the information is available via any one of them. Peer-to-peer technologies provide sophisticated solutions for this kind of loose integration of information sources. In our work, we consider digital libraries that organize documents according to a dedicated classification hierarchy or provide access to information on the basis of a thesaurus. These kinds of access mechanisms have proven to increase the retrieval result and are therefore widely used. On the other hand, this causes new problems as different sources will use different classifications and thesauri to organize information. This means, that we have to be able to mediate between these different structures. Integrating this mediation into the information retrieval process is a problem that to the best of our knowledge has not been addressed before

The Evolution of the Far-UV Luminosity Function and Star Formation Rate Density of the Chandra Deep Field South from z=0.2-1.2 with Swift/UVOT

We use deep Swift UV/Optical Telescope (UVOT) near-ultraviolet (1600A to 4000A) imaging of the Chandra Deep Field South to measure the rest-frame far-UV (FUV; 1500A) luminosity function (LF) in four redshift bins between z=0.2 and 1.2. Our sample includes 730 galaxies with u < 24.1 mag. We use two methods to construct and fit the LFs: the traditional V_max method with bootstrap errors and a maximum likelihood estimator. We observe luminosity evolution such that M* fades by ~2 magnitudes from z~1 to z~0.3 implying that star formation activity was substantially higher at z~1 than today. We integrate our LFs to determine the FUV luminosity densities and star formation rate densities from z=0.2 to 1.2. We find evolution consistent with an increase proportional to (1+z)^1.9 out to z~1. Our luminosity densities and star formation rates are consistent with those found in the literature, but are, on average, a factor of ~2 higher than previous FUV measurements. In addition, we combine our UVOT data with the MUSYC survey to model the galaxies' ultraviolet-to-infrared spectral energy distributions and estimate the rest-frame FUV attenuation. We find that accounting for the attenuation increases the star formation rate densities by ~1 dex across all four redshift bins.Comment: 20 pages, 8 figures, 6 tables; accepted for publication in Ap