Time filter

Source Type

Richmond, VA, United States

Using a hyperbolic model and curve-fitting techniques, curves of the nonlinear side resistance (fs) versus the ratio of shaft displacement to shaft diameter (D/d), measured in top-down static load tests on instrumented drilled shafts in multilayered deposits of soil and intermediate geomaterials (IGMs), have been analyzed to determine the values of shear modulus (G) and ultimate side friction (fsu). Values of G and fsu for each layer of soil and IGM so determined from load tests matched well with those determined from correlations. An iterative procedure based on hyperbolic curves of fs versus D/d derived using values of G and fsu determined either from correlations or from load tests was used to compute or back-calculate top-down load-settlement curves. The load-settlement curves determined via this procedure matched well with those measured from the top-down load tests both when the tip bears above a cavity or very soft soils and when the tip is bearing in a firm and dense IGM. It was found that an accurate axial load distribution and settlement profile along the length of a shaft can be determined via this procedure. Copyright © 2013 by ASTM International. Source

Mitnick C.D.,Harvard University | Rodriguez C.A.,Harvard University | Hatton M.L.,Boston University | Brigden G.,Medecins Sans Frontieres | And 13 more authors.
PLoS ONE | Year: 2016

Introduction There are numerous challenges in delivering appropriate treatment for multidrug-resistant tuberculosis (MDR-TB) and the evidence base to guide those practices remains limited. We present the third updated Research Agenda for the programmatic management of drugresistant TB (PMDT), assembled through a literature review and survey. Methods Publications citing the 2008 research agenda and normative documents were reviewed for evidence gaps. Gaps were formulated into questions and grouped as in the 2008 research agenda: Laboratory Support, Treatment Strategy, Programmatically Relevant Research, Epidemiology, and Management of Contacts. A survey was distributed through snowball sampling to identify research priorities. Respondent priority rankings were scored and summarized by mean. Sensitivity analyses explored weighting and handling of missing rankings. Results Thirty normative documents and publications were reviewed for stated research needs; these were collapsed into 56 research questions across 5 categories. Of more than 500 survey recipients, 133 ranked priorities within at least one category. Priorities within categories included new diagnostics and their effect on improving treatment outcomes, improved diagnosis of paucibacillary and extra pulmonary TB, and development of shorter, effective regimens. Interruption of nosocomial transmission and treatment for latent TB infection in contacts of known MDR-TB patients were also top priorities in their respective categories. Results were internally consistent and robust. Discussion Priorities retained from the 2008 research agenda include shorter MDR-TB regimens and averting transmission. Limitations of recent advances were implied in the continued quest for: shorter regimens containing new drugs, rapid diagnostics that improve treatment outcomes, and improved methods of estimating burden without representative data. Conclusion There is continuity around the priorities for research in PMDT. Coordinated efforts to address questions regarding shorter treatment regimens, knowledge of disease burden without representative data, and treatment for LTBI in contacts of known DR-TB patients are essential to stem the epidemic of TB, including DR-TB.This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Source

Benson-Davies S.,Central Office | Davies M.L.,VA Black Hills Health Care System | Kattelmann K.,South Dakota State University
Topics in Clinical Nutrition | Year: 2013

In a cross-sectional pilot study, we examined eating behaviors in patients (N= 24) approximately 6 years after gastric bypass surgery. Anthropometric measures, personal interviews, and 7 days of food records were collected. A mean body mass index of 33.7 ± 8 was reported, with 75% (18/24) sustaining a weight loss 50% or more of their excess body weight. A mean total caloric intake of 1429 ± 411 cal was reported: 43% carbohydrate, 17% protein, and 39% fat. Subjects reported "returning to old eating habits" with a diet high in liquid calories (soda, coffee drinks, sports drinks, alcohol), sweets (chocolate, cookies), convenience foods, and fast food consumption. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source

Gupta R.C.,Central Office
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2012

Analyses of load tests on instrumented drilled shafts in intermediate geomaterials (IGMs) and rock are performed using a hyperbolic modelfor relative displacement(Δ)/shaft diameter (d)versus side friction (fs) data. Ultimate side friction (fsu) determined from these analyses for IGMs compares well with those determined from pressuremeter tests. For rock with a rock quality designation (RQD) greater than 50%, values of fsu are approximately equal to rock socket unit friction (qSR), estimated using 28-day strength (f'c) of drilled shaft concrete, but for RQD less than 50%, fsu is approximately equal to qSR, estimated using uniaxial strength (qu) of rock cores and reduction factor (αE) to account for jointing in rock. Linear elastic shear modulus (G) for IGMs determined from these analyses is approximately equal or slightly less than reload modulus (Gr) determined from the pressuremeter test. Rock mass modulus (Em) also matches with values determined from correlations. © 2012 American Society of Civil Engineers. Source

Tsan L.,Central Office | Langberg R.,Central Office | Davis C.,Central Office | Phillips Y.,Central Office | And 10 more authors.
American Journal of Infection Control | Year: 2010

Background: Little is known about factors contributing to nursing home-associated infections (NHAIs). We conducted a survey of residents in 133 Department of Veterans Affairs community living centers to determine the roles of indwelling device use, bed locations, and treatment codes on NHAIs. Methods: A Web-based point prevalence survey of NHAIs using modified Centers for Disease Control and Prevention definitions for health care-associated infections was conducted on November 14, 2007. Results: Among 10,939 residents, 575 had at least one NHAI, for a point prevalence rate of 5.3%. Urinary tract infection, skin infection, asymptomatic bacteriuria, and pneumonia were the most prevalent NHAIs. A total of 2687 residents had one or more indwelling devices; 290 of these also had an NHAI, for a prevalence of 10.8%. In contrast, the prevalence of NHAIs in residents without indwelling devices was 3.5% (P < .0001). Indwelling urinary catheters, percutaneous gastrostomy tubes, peripherally inserted central catheters, and suprapubic urinary catheters were the most commonly used devices. There were 4027 residents in designated units and 6912 residents in dispersed units. The rate of device use was 21.4% in the designated units and 26.4% in the dispersed units (P < .0001). The prevalence of NHAIs was 4.5% in the designated units and 5.7% in the dispersed units (P < .001). Rates of NHAIs and device use varied greatly among the various treatment codes; however, there was a positive correlation between the rates of NHAIs and device use. Stepwise logistic regression analysis of data from long-stay and short-stay skilled nursing care residents revealed that only the presence of an indwelling device, not length of stay or bed location, affected the rate of NHAIs. Conclusion: Indwelling device use, but not bed location or treatment code, was found to be associated with increased rate of NHAIs. Source

Discover hidden collaborations