5,779 research outputs found
Effect Of Gap Size On Performance Of Metal-plated Joints In Compression
Metal-plate splice joints with gaps between butting pieces of 2 x 4 lumber were tested in compression to evaluate the effect of gap size on joint serviceability performance. The current design methodology for compression splice joints was also evaluated. Specimens representing floor and roof truss compression joints, with 16- and 20-gauge plates of staggered and aligned tooth configurations, were tested for each of two gap sizes.Generally, 20-gauge and 16-gauge plates on joints with 1/8 in. nominal maximum gaps buckled under compression loads while 16-gauge plates on joints with nominal 1/16 in. maximum gaps did not buckle before the gap closed. Gap closure with the latter joints was due principally to slip between the teeth nearest the splice and the wood. Joints with 16-gauge plates generally outperformed those with 20-gauge plates, based on the serviceability performance indicators of the test compression splice joints. Furthermore, gap size had less of an influence on joints with 16-gauge plates than on joints with 20-gauge plates.The current practice of sizing plates for compression splices to withstand one-half of the calculated chord force could not be physically confirmed using joint serviceability criteria. The test results indicated that basing allowable plate ratings on a surface-area basis derived from tension tests is misleading
The SNARE Protein Syntaxin 3 Confers Specificity for Polarized Axonal Trafficking in Neurons.
Cell polarity and precise subcellular protein localization are pivotal to neuronal function. The SNARE machinery underlies intracellular membrane fusion events, but its role in neuronal polarity and selective protein targeting remain unclear. Here we report that syntaxin 3 is involved in orchestrating polarized trafficking in cultured rat hippocampal neurons. We show that syntaxin 3 localizes to the axonal plasma membrane, particularly to axonal tips, whereas syntaxin 4 localizes to the somatodendritic plasma membrane. Disruption of a conserved N-terminal targeting motif, which causes mislocalization of syntaxin 3, results in coincident mistargeting of the axonal cargos neuron-glia cell adhesion molecule (NgCAM) and neurexin, but not transferrin receptor, a somatodendritic cargo. Similarly, RNAi-mediated knockdown of endogenous syntaxin 3 leads to partial mistargeting of NgCAM, demonstrating that syntaxin 3 plays an important role in its targeting. Additionally, overexpression of syntaxin 3 results in increased axonal growth. Our findings suggest an important role for syntaxin 3 in maintaining neuronal polarity and in the critical task of selective trafficking of membrane protein to axons
Proximity Operations and Docking Sensor Development
The Next Generation Advanced Video Guidance Sensor (NGAVGS) has been under development for the last three years as a long-range proximity operations and docking sensor for use in an Automated Rendezvous and Docking (AR&D) system. The first autonomous rendezvous and docking in the history of the U.S. Space Program was successfully accomplished by Orbital Express, using the Advanced Video Guidance Sensor (AVGS) as the primary docking sensor. That flight proved that the United States now has a mature and flight proven sensor technology for supporting Crew Exploration Vehicles (CEV) and Commercial Orbital Transport Systems (COTS) Automated Rendezvous and Docking (AR&D). NASA video sensors have worked well in the past: the AVGS used on the Demonstration of Autonomous Rendezvous Technology (DART) mission operated successfully in spot mode out to 2 km, and the first generation rendezvous and docking sensor, the Video Guidance Sensor (VGS), was developed and successfully flown on Space Shuttle flights in 1997 and 1998. 12 Parts obsolescence issues prevent the construction of more AVGS units, and the next generation sensor was updated to allow it to support the CEV and COTS programs. The flight proven AR&D sensor has been redesigned to update parts and add additional capabilities for CEV and COTS with the development of the Next Generation AVGS at the Marshall Space Flight Center. The obsolete imager and processor are being replaced with new radiation tolerant parts. In addition, new capabilities include greater sensor range, auto ranging capability, and real-time video output. This paper presents some sensor hardware trades, use of highly integrated laser components, and addresses the needs of future vehicles that may rendezvous and dock with the International Space Station (ISS) and other Constellation vehicles. It also discusses approaches for upgrading AVGS to address parts obsolescence, and concepts for minimizing the sensor footprint, weight, and power requirements. In addition, the testing of the brassboard and proto-type NGAVGS units will be discussed along with the use of the NGAVGS as a proximity operations and docking sensor
Urban-rural variations in quality-of-life in breast cancer survivors prescribed endocrine therapy
The number of breast cancer survivors has increased as a result of rising incidence and increased survival. Research has revealed significant urban–rural variation in clinical aspects of breast cancer but evidence in the area of survivorship is limited. We aimed to investigate whether quality of life (QoL) and treatment-related symptoms vary between urban and rural breast cancer survivors prescribed endocrine therapy. Women with a diagnosis of stages I–III breast cancer prescribed endocrine therapy were identified from the National Cancer Registry Ireland and invited to complete a postal survey (N= 1606; response rate = 66%). A composite measure of urban–rural classification was created using settlement size, population density and proximity to treatment hospital. QoL was measured using the Functional Assessment of Cancer Therapy (FACT-G) and an endocrine subscale. The association between urban–rural residence/status and QoL and endocrine symptoms was assessed using linear regression with adjustment for socio-demographic and clinical covariates. In multivariable analysis, rural survivors had a statistically significant higher overall QoL (β = 3.81, standard error (SE) 1.30,p< 0.01), emotional QoL (β = 0.70, SE 0.21,p< 0.01) and experienced a lower symptom burden (β = 1.76, SE 0.65,p< 0.01) than urban survivors. QoL in breast cancer survivors is not simply about proximity and access to healthcare services but may include individual and community level psychosocial factors
Inclusive teaching circles : mechanisms for creating welcoming classrooms.
This essay examines the Inclusive Teaching Circle (ITC) as a mechanism for faculty development in creating instructional tools that embrace an inclusive pedagogy reflecting diversity, cultural competence and social justice. We describe one group’s year-long participation in an ITC at a large, metropolitan research university in the south. Next, we share several members’ strategies for promoting more inclusive and equitable learning for students in our classrooms. Finally, we consider the implications of ITCs for its group participants and the professorate at large
Mannose binding lectin is required for alphavirus-induced arthritis/myositis
Mosquito-borne alphaviruses such as chikungunya virus and Ross River virus (RRV) are emerging pathogens capable of causing large-scale epidemics of virus-induced arthritis and myositis. The pathology of RRV-induced disease in both humans and mice is associated with induction of the host inflammatory response within the muscle and joints, and prior studies have demonstrated that the host complement system contributes to development of disease. In this study, we have used a mouse model of RRV-induced disease to identify and characterize which complement activation pathways mediate disease progression after infection, and we have identified the mannose binding lectin (MBL) pathway, but not the classical or alternative complement activation pathways, as essential for development of RRV-induced disease. MBL deposition was enhanced in RRV infected muscle tissue from wild type mice and RRV infected MBL deficient mice exhibited reduced disease, tissue damage, and complement deposition compared to wild-type mice. In contrast, mice deficient for key components of the classical or alternative complement activation pathways still developed severe RRV-induced disease. Further characterization of MBL deficient mice demonstrated that similar to C3(-/-) mice, viral replication and inflammatory cell recruitment were equivalent to wild type animals, suggesting that RRV-mediated induction of complement dependent immune pathology is largely MBL dependent. Consistent with these findings, human patients diagnosed with RRV disease had elevated serum MBL levels compared to healthy controls, and MBL levels in the serum and synovial fluid correlated with severity of disease. These findings demonstrate a role for MBL in promoting RRV-induced disease in both mice and humans and suggest that the MBL pathway of complement activation may be an effective target for therapeutic intervention for humans suffering from RRV-induced arthritis and myositis.This work was supported by NIH/NIAMS R01 AR 047190 awarded to MTH
Race differences in the physical and psychological impact of hypertension labeling
Background - Blood pressure screening is an important component of cardiovascular disease prevention, but a hypertension diagnosis (i.e., label) can have unintended negative effects on patients' well-being. Despite persistent disparities in hypertension prevalence and outcomes, whether the impact of labeling differs by race is unknown. The purpose of this study was to evaluate possible race differences in the relationship between hypertension labeling and health-related quality of life and depression.
Methods - The sample included 308 normotensive and unmedicated hypertensive subjects from the Neighborhood Study of Blood Pressure and Sleep, a cross-sectional study conducted between 1999 and 2003. Labeled hypertension was defined (by self-report) as having been diagnosed with high blood pressure or prescribed antihypertensive medications. Effects of labeling and race on self-reported physical and mental health and depressive symptoms were tested using multivariate analysis of covariance, controlling for age, sex, body mass index (BMI), previous medication use, and “true” hypertension status, defined by average daytime ambulatory blood pressure (ABP).
Results - Both black and white subjects who had been labeled as hypertensive reported similarly poorer physical health than unlabeled subjects (P = 0.001). However, labeling was associated with poorer mental health and greater depressive symptoms only among blacks (Ps < 0.05 for the interactions). These findings were not explained by differences in socioeconomic status.
Conclusions - These results are consistent with previous studies showing negative effects of hypertension labeling, and demonstrate important race differences in these effects. Clinical approaches to communicating diagnostic information that avoid negative effects on well-being are needed, and may require tailoring to patient characteristics such as race
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