Exponent

About: Exponent is a company organization based out in Menlo Park, California, United States. It is known for research contribution in the topics: Population & Risk assessment. The organization has 1589 authors who have published 2680 publications receiving 88140 citations.

Risk Adjustment Is Necessary in Medicare Bundled Payment Models for Total Hip and Knee Arthroplasty.

Abstract: Background Concerns exist that high-risk patients in alternative payment models may face difficulties with access to care without proper risk adjustment. The purpose of this study is to identify the effect of medical and orthopedic specific risk factors on the cost of a 90-day episode of care following total hip (THA) and knee arthroplasty (TKA). Methods We queried the Medicare 5% Limited Data Set for all patients undergoing primary THA and TKA from 2010 to 2014. To evaluate the cost of an episode of care, we calculated all claims for 90 days following surgery. Multivariate analysis was performed to quantify the added episode-of-care costs for demographic variables, geography, medical comorbidities, and orthopedic specific risk factors. Results Of the 58,809 TKA patients, the median 90-day Medicare costs was $23,800 (interquartile range, $18,900-$32,300), while the median of the 27,293 THA patients was $24,000 (interquartile range, $18,500-$33,900). Independent risk factors (all P Conclusion Certain comorbidities and orthopedic risk factors increase 90-day episode-of-care costs in the Medicare population. The current lack of proper risk stratification could be a powerful driver of decreased access to care for our most medically challenged members of society.

Strength and reliability of alumina ceramic femoral heads: Review of design, testing, and retrieval analysis.

Abstract: Ceramic components are used increasingly in total hip arthroplasty (THA). Compared with metallic components, ceramic femoral heads for THA have the potential advantage of lower wear rates in articulations with acetabular liners. However, the use of ceramic components is also associated with unique risks, including sudden fracture and intolerable bearing noise or squeaking. This review paper summarizes the published literature regarding alumina ceramic femoral heads and tries to identify areas where uncertainties remain. We will discuss the following topics: (1) the fracture mechanics of ceramic materials; (2) design-related stresses acting on the femoral head, especially at the interface between the stem trunnion and the head; (3) gradual loss of strength in service by fatigue or slow crack growth and simulation using a proof test; and (4) information that can be gathered from examination of fractured explants.

Deer Track Bioreactor Experiment: Field-Scale Evaluation of Municipal Solid Waste Bioreactor Performance

Abstract: The Deer Track Bioreactor Experiment (DTBE) was a field-scale experiment conducted in a drainage lysimeter (8.2-m height, 2.4-m diameter) to assess the physical, chemical, and biological response of municipal solid waste with leachate addition. The experiment was operated for 1,067 days, with leachate dosing initiated on Day 399. Fresh leachate collected from a full-scale landfill was used for each dose. The ratio of cumulative leachate effluent to influent volume increased during dosing and leveled off at approximately 80%, indicating field capacity was achieved. Peak Darcy flux ranged from 2×10-7 m/s to 4×10-5 m/s, with larger flux computed for the last four doses when waste saturation was higher. During the experiment, the average dry unit weight of the waste increased 28% and the dry-weight water content (wd) increased 18%; field capacity of the waste was 44 to 48% on a dry-weight basis. Biochemical methane potential decreased from 51.4 to 3.4 mL-CH4/g-dry, indicating that 93% of the potent...

The degradation rate of thiamethoxam in European field studies.

Abstract: BACKGROUND Thiamethoxam is a systemic and contact pesticidal active substance in the neonicotinoid class of insecticides used worldwide to control a range of insects. Recently, concerns have been expressed regarding possible effects of neonicotinoids on bees and other wildlife. The DT50 of thiamethoxam in soil may be crucial to assessing the potential long-term exposure of non-target organisms to thiamethoxam. There are currently no detailed publicly available data for the field soil degradation of thiamethoxam under European conditions. We give field soil DT50 values of thiamethoxam from studies conducted in several European locations, under a range of realistic agronomic conditions. RESULTS Field soil DT50 values normalised to 20 °C ranged between 7.1 and 92.3 days (geomean = 31.2 days; n = 18). CONCLUSION The degradation rate of thiamethoxam was not significantly affected by application type, cropped fields versus bare soil, soil pH, organic matter content or repeated annual applications. Soil photolysis and leaching were negligible; therefore, calculated DT50 values were taken to represent microbial degradation. The field degradation rates of thiamethoxam were faster than those previously reported from laboratory degradation studies. They demonstrate that thiamethoxam will degrade to concentrations that are <10% of the maximum within a year of application, and will not accumulate in soil after repeated applications. © 2015 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.