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.

Comparative effectiveness of metal-on-metal and metal-on-polyethylene bearings in Medicare total hip arthroplasty patients.

Abstract: The purpose of this study was to compare the risk of complication and revision total hip arthroplasty (THA) in Medicare THA patients with different bearings. Using the 100% Medicare database (2005-2009), the adjusted risk of complication and revision THA was calculated for 148 827 THA patients (93 929 metal-on-polyethylene, 49 646 metal-on-metal, 5252 ceramic-on ceramic). Adjusted risk of deep vein thrombosis, dislocation, periprosthetic joint infection (PJI), mechanical loosening, periprosthetic fracture, and revision THA at up to 4 years postoperatively was compared using Cox regression. After adjusting for patient and hospital factors, metal-on-metal bearings were associated with higher risk of PJI ( P = .001), mechanical loosening ( P P = .031) than metal-on-polyethylene bearings and higher risk of PJI ( P = .014) than ceramic-on-ceramic bearings. Overall short-term revision rates did not vary significantly across bearing types, consistent with registry data. The benefits of hard-on-hard bearings in Medicare patients remain unproven, and further study is needed to compare long-term complication and revision rates in Medicare THA patients with different bearing types.

Dynamic Behavior of Structure-mounted Disk-shape Piezoelectric Sensors Including the Adhesive Layer

Abstract: Piezoelectric (PZT) transducers are commonly used for numerous diagnostic techniques for nondestructive evaluation (NDE) of structures Researchers in the past have shown that the presence of an adhesive layer between the PZT patch and the structure could have a significant impact both on the amplitude of the wave propagated into the structure and on its Electromechanical impedance (EMI) signature To account for losses, models have been developed to describe the effects of the adhesive layer Nonetheless, the models found in the literature are strictly valid for either 1D or rectangular PZT patches only The aim of this article is to develop a dynamic model for a disk, PZT patch connected to a structure by means of a thin adhesive layer Unlike previous works, it was found that for disk-shape sensors the effect of the adhesive layer is frequency dependent and that the losses due to the shear deformation of the adhesive layer for the case near the first radial resonant mode were considerably lower than for the quasi-static case In order to validate the model developed in this article, experimental data are compared to the predicted EMI signatures of disk-shape sensors mounted on a structure for various configurations

Resource Utilization Associated with Irritable Bowel Syndrome in the United States: 1987–1997

Abstract: This study uses national databases to examine the impact of irritable bowel syndrome (IBS) on resource utilization in the United States. Approximately 1.5–2.7 million physician visits (599–1043 per 100,000) yearly were related to IBS, with 45.3% seen by gastroenterologists, and 89% prescribed medications. Rates of physician visits by women were approximately 2.4–3.3 times higher than that for men. The average number of medication prescribed per visit was 1.83. Approximately 89% of the visits were prescribed with medications. The rate of hospitalization (5.1 per 100,000 in 1997) decreased by 60% and length of stay decreased from 5.5 to 3.1 days in the past decade. The average charges of IBS-related hospitalization were US$7,882. Our study found an apparent decreasing trend of IBS-related hospitalizations and no marked increase in office consultations in the past decade. However, a better case identification criterion is necessary to estimate the true disease burden.

Fault Sensing with an Artificial Reference Potential Provided by an Isolated Capacitance Effect

Abstract: When an electric tool or appliance loses its safety ground connection (due to the ground pin being cut or due to the use of a three-to-two adapter), and an internal fault occurs, the metal housing may become electrically "hot" resulting in a safety hazard This paper presents a Grounding Detector (GDT) circuit that could be used in conjunction with a Ground Fault Circuit Interrupter (GFCI) The advantage of the GDT over the GFCI is because the former monitors a voltage and the latter monitors a current The GDT continuously monitors the voltage on the metal housing of the appliance If the metal housing becomes electrically "hot", the GDT immediately detects this hazardous condition and takes corrective action, disconnecting the 120 Vac power from the hazardous appliance, and activating an alarm A GFCI would take no corrective action until a human comes in physical contact with the hazardous appliance resulting in the flow of ground fault current The authors have a United States patent on the GDT circuits