Development and Evaluation of Instrumented Soccer Equipment to Collect Ankle Joint Kinematics in the Field

Ankle sprains commonly occur during athletic competition and result in traumatic injury to the lateral ligament complex. Ankle ligament sprains are the most common injury type for intercollegiate soccer players and athletes that sustain lateral ankle sprains may lose game and/or practice time, have recurrent sprains due to ankle instability, incur proprioceptive deficits, and be at an increased risk of ankle osteoarthritis. The high rate of ankle injuries among soccer athletes demonstrates a need for novel and advanced data collection methodologies to reduce the incidence of lateral ankle sprains and improve injury prevention interventions. The purposes of this study were to develop instrumented soccer equipment to collect ankle joint kinematics in the field; establish the reliability and validity of a kinematic assessment using instrumented equipment during athletic maneuvers; and identify laboratory maneuvers that elicited game-like demands from athletes. Wireless orientation sensors were integrated into soccer shin guards and turf shoes. The instrumented equipment collected ankle joint kinematics during simulated athletic maneuvers in the laboratory and field. The simulated athletic maneuvers in the laboratory are commonly performed by soccer players and have been previously studied. Maneuvers included drop landing, drop jump, stop jump, and jump-stop cut. Drop landing and drop jump maneuvers resulted in poor to excellent reliability and very good to excellent validity. The stop jump maneuver resulted in poor to fair reliability and excellent validity. The jump-stop cut maneuver resulted in poor to excellent reliability and very good validity. The soccer-specific field maneuvers were jump header, moving jump header, and slalom. All maneuvers resulted in poor to good reliability. To identify laboratory maneuvers that elicited game-like demands, laboratory maneuvers of varied demand were compared to field maneuvers. Drop landing and drop jump maneuvers from a 60 cm platform elicited a similar response to the jump header maneuver. A jump distance recommendation for the stop jump maneuver was not warranted because jump distance did not significantly alter landing biomechanics. The instrumented equipment collected reliable and valid ankle joint kinematics in the sagittal plane and are a promising technology for in-game data collection and injury prevention

Superradiant lasing from J-aggregated molecules adsorbed onto colloidal silver

Cataloged from PDF version of article.The picosecond time-resolved emission spectrum of the cyanine dye 1,18-diethyl-3,38- bis-~3-sulfopropyl!-5,58,6,68-tetrachlorobenzimidazolocarbocyanine ~also known as BIC! adsorbed onto colloidal silver was examined as a function of laser pulse energy at room temperature. BIC is found to aggregate on colloidal silver, and the number of coherently responding molecules involved in the one-exciton state ~i.e., the coherence length! was estimated to involve 8–9 molecules. Lasing at a remarkably low incident pulse energy threshold was found for this system and explained in terms of a mechanism involving superradiant states created in coherently coupled adsorbed molecules that emit photons which stimulate emission from other spatially distributed superradiant states. © 1998 American Institute of Physics

Investigation of Interface Shear Stresses on Wheelchair Seat Cushions and the Effects on Subcutaneous Buttock Soft Tissues

Pressure ulcer incidence rates have remained constant [1] even though wheelchair seat cushion technologies have advanced. Shear stress is recognized as a risk factor for pressure ulcer development [2] and is a focus of many shear reduction technologies incorporated into cushions; however, shear reduction has not been quantified in the literature. This study evaluated 21 commercial wheelchair seat cushions using a methodology developed to quantify interface shear stress and calculate overall and local horizontal stiffness values. For statistical analyses, the cushions were grouped by Healthcare Common Procedure Coding System (HCPCS) codes. The general use cushion category (E2601) resulted in significantly greater interface shear stresses (p<.001) than all other categories and the adjustable skin protection cushion category (K0734) resulted in significantly less interface shear stress (p<.001) than all other categories. Additionally, this study provided evidence that the current horizontal stiffness test methodology (ISO 16840-2) [3] provides sufficient information to characterize wheelchair seat cushions, but does not directly quantify interface shear stress.Results from the evaluation of commercial wheelchair seat cushions provided evidence of materials and technologies that may reduce the risk of pressure ulcers. Based on these results, three prototype cushions were conceptualized and prototyped into a closed-loop control system. The closed-loop control system monitored interface stress amplitude to actively modulate cushion properties. None of the prototypes effectively reduced interface shear stress using the methodology developed for cushion testing.Subcutaneous buttock soft tissues were investigated using a finite element model. Researchers have previously used finite element models [4-13]; however, this study improved upon image collection methodology and validation techniques. MR images of one subject were collected in three seated postures and were used to create 3-D models of the buttock. A non-linear 3-D finite element model was developed with anatomical geometries using hyperelastic and viscoelastic constitutive models. Interface pressure, interface shear stress, and soft tissue displacements were used to validate the model. A parametric analysis resulted in a partially validated model that provided subcutaneous stresses and strains for the upright seated posture. The validated model will be used in future studies to evaluate the SCI population and to evaluate commercial and prototype wheelchair seat cushions

Superradiance of Aggregated Thiacarbocyanine Molecules

Emission lifetime and steady-state spectral measurements of aggregated and monomeric 3,3′-diethyl-5,5′-dichloro-9-phenylthiacarbocyanine (DDPT) in methanol and aqueous solutions at room temperature have been conducted. We deduce that in aqueous solution DDPT molecules that maintain their monomer emission lifetime and spectral properties exist intimately with molecules that are coherently interconnected in the excitonic structure. Simultaneous superradiance and monomer fluorescence from DDPT molecules occur and allows for a direct comparison of superradiance emission properties of aggregated molecules to the emission properties of the single molecule. We have found that the fluorescence lifetime of the aggregate is excitation wavelength dependent, and are led to conclude that superradiance by aggregated molecules and energy transfer from monomeric species to the aggregate play important roles in determining the optical dynamics of the aggregated system. We also report some of the photophysical properties of DDPT

Pasture Management in the US Midwest – An Assessment of Current Practices and Future Opportunities

Managed grazing offers significant potential to improve the sustainability of livestock farms in the US Midwest, however the benefits of managed grazing are largely influenced by the management practices employed on farm. The objective of this study was to gain an understanding of current grazing practices on Midwest farms and to identify the knowledge and support needs of graziers. A total of 185 responses were received from a range of different enterprises including dairy, beef, and sheep production. Results show a substantial degree of variation in grazing management practices between respondents and highlights significant scope for improvement on farms particularly in the areas of pasture measurement and budgeting, and grazing infrastructure. Reported benefits of managed grazing included lower environmental impact, better pasture and animal performance, better animal health and welfare, and lower costs. Challenges with managed grazing included time and labor input, maintaining pasture quantity and quality during the grazing season, adverse weather conditions such as excessive rain and drought, and animal health challenges such as heat stress, parasites and in some cases coyotes. The study highlighted opportunities for research and extension providers to better support farmers with information and advice and identified knowledge gaps in areas such as pasture species selection, soil fertility, grazing infrastructure, pasture budgeting, legumes, and pasture measurement. The study successfully gained an insight into graziers in the Midwest, the outputs of which, will be valuable to a number of key stakeholders going forward, including researchers, extension agents, farmers and policy makers

Comparison of feeding diets diluted with sorghum-sudangrass silage or low-quality grass on nutrient intake and digestibility and growth performance of Holstein dairy heifers

This study was carried out to evaluate the nutrient intakes and growth of dairy heifers offered an alfalfa silage– corn silage diet (CON; 14.3% crude protein, 61.1% total digestible nutrients, 47.9% neutral detergent fiber) compared with diets containing 1 of 2 types of sorghumsudangrass (SS) silages: conventional or photoperiod sensitive. The objective of the study was to determine the potential to use SS to control dry matter (DM) and nutrient intakes and weight gain. Both diets were similar in nutrient composition, with approximately 13% crude protein, 60 to 61% total digestible nutrients, and 55% neutral detergent fiber. Seventy-two Holstein heifers (16–18 mo at study initiation) were blocked by initial body weight (light = 422 ± 12.8 kg; medium = 455 ± 14.8 kg; heavy = 489 ± 16.7 kg) with 3 pens assigned to each weight block (8 heifers/pen; 24 heifers/block). The 3 diets were randomly allocated to the pens within each block and offered for 12 wk. Heifers offered the CON diet had greater DM, protein, and energy intakes compared with those offered the SS silage-based diets due to the greater neutral detergent fiber concentration of the SS diets. With lower DM and nutrient intakes, average daily gain was in the recommended range (0.8– 1 kg/d for Holstein heifers) for heifers offered the SS silage-based diets (mean of 0.92 kg/d for both SS diets vs. 1.11 kg/d for CON). Sorting behaviors for heifers offered both SS diets were more aggressive against long, medium, and short particles compared with those of heifers offered the CON diet; however, heifers sorted large particles from photoperiod-sensitive silage more aggressively than those from conventional silage. Based on this study, SS silage-based diets can control the DM and energy intakes for heifers and maintain optimum growth rates, with harvesting at a shorter chop length likely helping to alleviate sorting issues

Accurate dust temperature determination in a z = 7.13 galaxy

We report ALMA Band 9 continuum observations of the normal, dusty star-forming galaxy A1689-zD1 at z = 7.13, resulting in a ∼4.6 σ detection at 702 GHz. For the first time, these observations probe the far-infrared spectrum shortward of the emission peak of a galaxy in the Epoch of Reionization (EoR). Together with ancillary data from earlier works, we derive the dust temperature, Td, and mass, Md, of A1689-zD1 using both traditional modified blackbody spectral energy density fitting, and a new method that relies only on the [C ii] 158 μm line and underlying continuum data. The two methods give Td = (42+13-7, 40+13-) K, and Md} = (1.7+1.3-0.7, 2.0+1.8-1.0), 7, 107, M⊙. Band 9 observations improve the accuracy of the dust temperature (mass) estimate by ∼50 per cent (6 times). The derived temperatures confirm the reported increasing Td-redshift trend between z = 0 and 8; the dust mass is consistent with a supernova origin. Although A1689-zD1 is a normal UV-selected galaxy, our results, implying that ∼85 per cent of its star-formation rate is obscured, underline the non-negligible effects of dust in EoR galaxies