Pavement Testing Facility -- Design and Construction

DTFH61-85-C-00149The U.S. Accelerated Loading Facility (ALF), a full-scale accelerated pavement testing machine. has been installed at the Pavement Testing facility (PTF) at the Turner-Fairbank Highway Research Center (TFHRC). The report describes the design and construction of the two PTF test pavements, the materials used in their construction. and the associated pavement instrumentation and data acquisition system. The two test pavements contain hot-mix asphalt concrete with a crushed-aggregate base. The pavements were designed to carry 250.000 and 3.500.000 la-kip ESAL. Instrumentation was designed to automatically record pavement deflection. strain. temperature. surface profile, and wheel load. Software modules to acquire. reduce. and store the data in standard computer file format were developed

Structural Overlay Strategies for Jointed Concrete Pavements. Volume I: Sawing, and Sealing of Joints in AC Overlays of Concrete Pavements

DTFH61-86-C-00079A major field study and evaluation has been conducted into the effectiveness of three structural overlay types for portland cement concrete (PCC) pavements. These include sawing and sealing asphalt concrete (AC) overlays of PCC pavements, cracking and seating PCC pavement prior to AC overlay, and constructing a thin bonded PCC overlay on top of the existing PCC pavement. Condition surveys, deflection testing, and roughness measurements were performed on a total of 55 sections. Based on the field data, guidelines were developed for the use of structural overlays. In addition, the results of this study were used to revise and enhance the EXPEAR rehabilitation advisory system. This volume examines the effectiveness of the sawing and sealing of AC overlays of PCC pavements. Sawing and sealing is an attempt to control, not prevent, the occurrence and severity of reflective cracks from the underlying PCC slabs. Joints are sawed in the AC overlay directly above joints in the existing slab and then immediately sealed. The first part of this report examines the literature and evaluates the performance of in-service saw and seal overlays. Part II develops many of the recommendations from the research effort into guidelines for techniques and specification for sawing and sealing operations

Final report on LDRD project : elucidating performance of proton-exchange-membrane fuel cells via computational modeling with experimental discovery and validation.

In this report, we document the accomplishments in our Laboratory Directed Research and Development project in which we employed a technical approach of combining experiments with computational modeling and analyses to elucidate the performance of hydrogen-fed proton exchange membrane fuel cells (PEMFCs). In the first part of this report, we document our focused efforts on understanding water transport in and removal from a hydrogen-fed PEMFC. Using a transparent cell, we directly visualized the evolution and growth of liquid-water droplets at the gas diffusion layer (GDL)/gas flow channel (GFC) interface. We further carried out a detailed experimental study to observe, via direct visualization, the formation, growth, and instability of water droplets at the GDL/GFC interface using a specially-designed apparatus, which simulates the cathode operation of a PEMFC. We developed a simplified model, based on our experimental observation and data, for predicting the onset of water-droplet instability at the GDL/GFC interface. Using a state-of-the-art neutron imaging instrument available at NIST (National Institute of Standard and Technology), we probed liquid-water distribution inside an operating PEMFC under a variety of operating conditions and investigated effects of evaporation due to local heating by waste heat on water removal. Moreover, we developed computational models for analyzing the effects of micro-porous layer on net water transport across the membrane and GDL anisotropy on the temperature and water distributions in the cathode of a PEMFC. We further developed a two-phase model based on the multiphase mixture formulation for predicting the liquid saturation, pressure drop, and flow maldistribution across the PEMFC cathode channels. In the second part of this report, we document our efforts on modeling the electrochemical performance of PEMFCs. We developed a constitutive model for predicting proton conductivity in polymer electrolyte membranes and compared model prediction with experimental data obtained in our laboratory and from literature. Moreover, we developed a one-dimensional analytical model for predicting electrochemical performance of an idealized PEMFC with small surface over-potentials. Furthermore, we developed a multi-dimensional computer model, which is based on the finite-element method and a fully-coupled implicit solution scheme via Newton's technique, for simulating the performance of PEMFCs. We demonstrated utility of our finite-element model by comparing the computed current density distribution and overall polarization with those measured using a segmented cell. In the last part of this report, we document an exploratory experimental study on MEA (membrane electrode assembly) degradation

The proteome of Toxoplasma gondii: integration with the genome provides novel insights into gene expression and annotation

A proteomics analysis identifies one third of the predicted Toxoplasma gondii proteins and integrates proteomics and genomics data to refine genome annotation

Formulaic Language in Native and Second Language Speakers: Psycholinguistics, Corpus Linguistics, and TESOL

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89473/1/j.1545-7249.2008.tb00137.x.pd

Survival enhancing indications for coronary artery bypass graft surgery in California

<p>Abstract</p> <p>Background</p> <p>Coronary artery bypass graft (CABG) surgery is performed because of anticipated survival benefit, improvement in quality of life, or both. We performed this study to explore variations in clinical indications for CABG surgery among California hospitals and surgeons.</p> <p>Methods</p> <p>Using California CABG Outcomes Reporting Program data, we classified all isolated CABG cases in 2003–2004 as having "probable survival enhancing indications (SEIs)", "possible SEIs" or "non-SEIs." Patient and hospital characteristics associated with SEIs were examined.</p> <p>Results</p> <p>While 82.9% of CABG were performed for probable SEIs, the range extended from 68% to 96% among hospitals and 51% to 100% among surgeons. SEI rates were higher among patients aged ≥ 65 compared with those aged 18–64 (Adjusted Odds Ratio [AOR] > 1.29 for age groups 65–69, 70–74 and ≥ 75; all p < 0.001), among Asians and Native Americans compared with Caucasians (AOR 1.22 and 1.15, p < 0.001); and among patients with hypertension, peripheral vascular disease, diabetes, cerebrovascular disease and congestive heart failure compared to patients without these conditions (AOR > 1.09, all p < 0.001). Variations in indications for surgery were more strongly related to patient mix than to surgeon or hospital effects (intraclass correlation [ICC] = 0.04 for hospital; ICC = 0.01 for surgeon).</p> <p>Conclusion</p> <p>California hospitals and surgeons vary in their distribution of indications for CABG surgery. Further research is required to identify the roles of market factors, referral patterns, patient preferences, and local clinical culture in producing the observed variations.</p