245 research outputs found

    Review of Erosion and Sedimentation Control Programs in the Piscataqua Region

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    The Piscataqua Region Estuaries Partnership (PREP) seeks to minimize adverse impacts to water resources associated with construction site development activities. In order to achieve this goal, PREP must understand the strengths and weaknesses of existing erosion and sedimentation control (E&SC) programs in the 52 municipalities of the PREP water shed (Figure 1-1). A detailed understanding of the existing E&SC programs will enable PREP and other stakeholders to identify and implement actions to improve E&SC programs and minimize adverse impacts. This report provides a review and assessment of existing erosion and sedimentation control programs and a set of recommendations for improving these programs. Our approach in conducting the review was to obtain available federal, state and municipal programs data and to interview people who work with E&SC programs on a daily basis, including state, municipal, construction contractor and site inspector staff. A statement of the problem, an introduction to applicable regulations, and a description of our project approach are provided below

    A Terraced Scanning Superconducting Quantum Interference Device Susceptometer with Sub-Micron Pickup Loops

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    Superconducting Quantum Interference Devices (SQUIDs) can have excellent spin sensitivity depending on their magnetic flux noise, pick-up loop diameter, and distance from the sample. We report a family of scanning SQUID susceptometers with terraced tips that position the pick-up loops 300 nm from the sample. The 600 nm - 2 um pickup loops, defined by focused ion beam, are integrated into a 12-layer optical lithography process allowing flux-locked feedback, in situ background subtraction and optimized flux noise. These features enable a sensitivity of ~70 electron spins per root Hertz at 4K.Comment: See http://stanford.edu/group/moler/publications.html for an auxiliary document containing additional fabrication details and discussio

    Health Care for the Poor in Omaha-Douglas County: Problems and Policy Options

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    The health-care system in Omaha-Douglas County is on the verge of dramatic changes because of federal cutbacks, expanding cost-containment efforts, and an increasingly competitive medical market. As a result, problems are now arising because of increasing difficulties in providing health care to the poor

    Damage Evolution in Complex-Phase and Dual-Phase Steels during Edge Stretching

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    The role of microstructural damage in controlling the edge stretchability of Complex-Phase (CP) and Dual-Phase (DP) steels was evaluated using hole tension experiments. The experiments considered a tensile specimen with a hole at the center of specimen that is either sheared (sheared edge condition) or drilled and then reamed (reamed edge condition). The damage mechanism and accumulation in the CP and DP steels were systematically characterized by interrupting the hole tension tests at different strain levels using scanning electron microscope (SEM) analysis and optical microscopy. Martensite cracking and decohesion of ferrite-martensite interfaces are the dominant nucleation mechanisms in the DP780. The primary source of void nucleation in the CP800 is nucleation at TiN particles, with secondary void formation at martensite/bainite interfaces near the failure strain. The rate of damage evolution is considerably higher for the sheared edge in contrast with the reamed edge since the shearing process alters the microstructure in the shear affected zone (SAZ) by introducing work-hardening and initial damage behind the sheared edge. The CP microstructures were shown to be less prone to shear-induced damage than the DP materials resulting in much higher sheared edge formability. Microstructural damage in the CP and DP steels was characterized to understand the interaction between microstructure, damage evolution and edge formability during edge stretching. An analytical model for void evolution and coalescence was developed and applied to predict the damage rate in these rather diverse microstructures.Natural Sciences and Engineering Research Council of Canada (NSERC) AUTO21 Network of Centres of Excellence Canada Research Chairs Secretaria

    Acetabular fracture types vary with different acetabular version

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    Purpose: Acetabular fractures typically occur in high energy trauma. Understanding of the various contributing biomechanical factors and trauma mechanisms is still limited. While several investigations figured out what role femoral position during impact plays in distinct fracture patterns, no data exists on the influence of acetabular version on the fracture type. Our study was carried out to clarify this issue. Methods: Radiological data sets of 192 patients (145 male, 47 female, age 14-90years) sustaining acetabular fractures were assessed retrospectively. The crossover ratio of the crossover sign and presence or absence of the posterior wall sign and ischial spine sign were used to determine acetabular retroversion on conventional radiographs. Acetabular version in the axial plane was measured on a computed tomography (CT) scan. Statistics were then performed to analyse the relationship between the acetabular fracture type according to the Letournel classification and acetabular version. Results: A significant difference (p = 0.029) in acetabular version was found between fractures of the anterior [mean equatorial edge (EE) angle 19.93°] and posterior (mean EE angle 17.53°) acetabulum in the CT scan. No difference was shown on the measurements on conventional radiographs. Conclusions: Acetabular version in the axial plane has an influence on the acetabular fracture pattern. While more anteverted acetabula were frequently associated with anterior fracture types according to the Letournel classification, retroversion of the acetabulum was associated with posterior fracture type

    Relationship between Wiberg's lateral center edge angle, Lequesne's acetabular index, and medial acetabular bone stock

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    Objective: Knowledge of acetabular anatomy is crucial for cup positioning in total hip replacement. Medial wall thickness of the acetabulum is known to correlate with the degree of developmental dysplasia of the hip (DDH). No data exist about the relationship of routinely used radiographic parameters such as Wiberg's lateral center edge angle (LCE-angle) or Lequesne's acetabular index (AI) with thickness of the medial acetabular wall in the general population. The aim of our study was to clarify the relationship between LCE, AI, and thickness of the medial acetabular wall. Materials and methods: Measurements on plain radiographs (LCE and AI) and axial CT scans (quadrilateral plate acetabular distance QPAD) of 1,201 individuals (2,402 hips) were obtained using a PACS imaging program and statistical analyses were performed. Results: The mean thickness of the medial acetabulum bone stock (QPAD) was 1.08mm (95% CI: 1.05-1.10) with a range of 0.1 to 8.8mm. For pathological values of either the LCE (12°) the medial acetabular wall showed to be thicker than in radiological normal hips. The overall correlation between coxometric indices and medial acetabular was weak for LCE (r=−0.21. 95% CI [−0.25, -0.17]) and moderate for AI (r= 0.37, [0.33, 0.41]). Conclusions: We did not find a linear relationship between Wiberg's lateral center edge angle, Lequesne's acetabular index and medial acetabular bone stock in radiological normal hips but medial acetabular wall thickness increases with dysplastic indice

    Normal values of Wiberg's lateral center-edge angle and Lequesne's acetabular index-a coxometric update

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    Background: The historical pathological cut-off values for Wiberg's lateral center-edge (LCE) angle and Lequesne's acetabular index (AI) are below 20° and above 12° for the LCE and AI, respectively. The aim of this study was to reassess these two angles more than 50years after their introduction using a standardized conventional radiological measurement method, considering changing social habits and their associated physiological changes. Methods: A total of 1,226 anteroposterior radiographs of the pelvis (2,452 hips) were obtained according to a strict standardized radiographic technique allowing reliable measurements of the LCE angle and the AI. Results: Distributions of the LCE and AI were pronouncedly Gaussian, with mean values of 33.6° for the LCE and 4.4° for the AI. The 2.5th and 97.5th empirical percentiles were 18.1 and 48.0° for the LCE and −6.9 and 14.9° for the AI. These intervals contained 95% of the data in our large sample. Small but statistically significant differences between the sexes and right and left hips have been demonstrated. Correlation between age and coxometric indices was low. Conclusion: The above findings do not conflict with the historical benchmarks. Statistical differences between sexes and between right and left hips were not clinically relevant. No conclusion can be drawn about coxometric indices and clinical manifestations of hip dysplasi
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