Skid-Test Trailer: Description, Evaluation and Adaptation

A two-wheeled skid-test trailer and towing vehicle were acquired in 1969. The trailer was designed primarily for measurement of steady-state friction at and above normal traffic speeds. Measurement of instantaneous wheel loads also permitted determination of peak or incipient friction. Factors and variables associated with the testing device and calibration and test procedures were investigated and standardized, and the trailer was adopted for routine testing. Comparative tests with the trailers of General Motors, Ohio, and West Virginia were conducted, and the data were correlated. The interim standard method of test using an automobile was correlated with the trailer to permit conversion of data accumulated in preceding years

Skid Resistance of Pavements [Sept. 1972]

Standard pavement types and experimental surfaces on roads throughout Kentucky were evaluated in terms of skid resistance and effects of traffic, wear, and polishing. Friction-vs-speed gradients and the relationships between locked-wheel and incipient friction were determined. Asphaltic concrete pavements on high-speed, four-lane roads were found to be significantly more skid resistant than on two-lane highways and somewhat more skid resistant than concrete surfaces (especially those containing calcareous gravel aggregates). Sand-asphalt surfaces containing significant proportions of limestone sands showed inadequate level of friction for the traffic sustained. Several experimental sand asphalts without limestone sands exhibited greater skid resistance; Kentucky rock asphalt surfaces remain the most skid resistant of all surfaces investigated

Accidents on Rural Interstate and Parkway Roads and Their Relation to Pavement Friction

Friction measurements were made with a skid trailer at 70 mph (31 m/s) on 770 miles (1240 km) of rural, four-lane, controlled-access routes on the interstate and parkway systems in Kentucky. Each construction project was treated as a test section. Accident experience, friction measurements, and traffic volumes were obtained for each. Various relationships between wet-weather accidents and skid resistance were analyzed. The expression of accident occurrence which correlated best with skid and slip resistance was wet-weather accidents per 100 million vehicle miles. Accidents increased greatly as Skid Numbers (70 mph or 31 m/s) decreased from 27 ± 1. Analysis of Peak Slip Numbers and accident occurrences indicated similar trends

Skid Resistance of Pavements [July 1972]

Standard pavement types and experimental surfaces on roads throughout Kentucky were evaluated in terms of skid resistance and effects of traffic, wear, and polishing. Friction-vs-speed gradients and the relationships between locked-wheel and incipient friction were determined. Class I bituminous pavements on high-speed, four-lane roads were found to be significantly more skid resistant than on two-lane highways and somewhat more skid resistant than concrete surfaces (especially those containing calcareous gravel aggregates). Sand-asphalt surfaces containing significant proportions of limestone sands showed inadequate level of friction for the traffic sustained. Several experimental sand asphalts without limestone sands exhibited greater skid resistance; Kentucky rock asphalt surfaces remain the most skid resistant of all surfaces investigated

Accidents on Rural Interstate and Parkway Roads and their Relation to Pavement Friction

Friction measurements were made with a skid trailer at 70 mph (31 m/s) on 770 miles (1240 km) of rural, four-lane, controlled-access routes on the interstate and parkway systems in Kentucky. Each construction project was treated as a test section. Accident experience, friction measurements, and traffic volumes were obtained for each. Various relationships between wet-weather accidents and skid resistance were analyzed. Averaging methods were used as a means of developing trends and minimizing scatter. A moving average for progressively-ordered sets of five test sections yielded more definite results. The expression of accident occurrence which correlated best with skid and slip resistance was wet-weather accidents per 100 million vehicle miles (161 million vehicle kilometers). Accidents increased greatly as Skid Numbers (70 mph or 31 m/s) decreased from 27. Analysis of Peak Slip Numbers and accident occurrences indicated similar trends

Transgenic camelina oil is an effective source of eicosapentaenoic acid and docosahexaenoic acid in diets for farmed rainbow trout, in terms of growth, tissue fatty acid content, and fillet sensory properties

The oilseed Camelina sativa was genetically engineered to produce eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at levels similar to fish oil (FO), which we tested as a lipid source in diets for rainbow trout. Three experimental diets were tested, a FO control, a low‐level transgenic camelina oil (LCO) diet (no FO with 12.5 g/kg camelina), and a high‐level transgenic camelina oil (HCO) diet (no FO with 130 g/kg transgenic camelina). Trout (initial weight 49.8 ± 11 g/fish) were fed for 12 weeks and were evaluated for growth performance, fatty acid content (muscle, liver, brain, and eye), and sensory properties of fillets. The final lengths and weights of fish fed LCO and HCO diets were higher compared to fish fed FO. There were no differences in weight gain, condition factor, specific growth rate, feed intake, and feed conversion ratio. EPA in muscle tissue was higher in fish fed HCO and FO diets compared to the LCO diet. Compound‐specific stable isotope analysis revealed that rainbow trout fed the FO diet stored isotopically enriched DHA compared to the lighter DHA in fish fed HCO. Trout fillets from the HCO treatment were firmer in texture and had a higher orange intensity compared to the FO group

Overexpression of an endogenous type 2 diacylglycerol acyltransferase in the marine diatom Phaeodactylum tricornutum enhances lipid production and omega-3 long-chain polyunsaturated fatty acid content

Background: Oleaginous microalgae represent a valuable resource for the production of high-value molecules. Considering the importance of omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) for human health and nutrition the yields of high-value eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) require significant improvement to meet demand; however, the current cost of production remains high. A promising approach is to metabolically engineer strains with enhanced levels of triacylglycerols (TAGs) enriched in EPA and DHA. Results: Recently, we have engineered the marine diatom Phaeodactylum tricornutum to accumulate enhanced levels of DHA in TAG. To further improve the incorporation of omega-3 LC-PUFAs in TAG, we focused our effort on the identification of a type 2 acyl-CoA:diacylglycerol acyltransferase (DGAT) capable of improving lipid production and the incorporation of DHA in TAG. DGAT is a key enzyme in lipid synthesis. Following a diatom based in vivo screen of candidate DGATs, a native P. tricornutum DGAT2B was taken forward for detailed characterisation. Overexpression of the endogenous P. tricornutum DGAT2B was confirmed by qRT-PCR and the transgenic strain grew successfully in comparison to wildtype. PtDGAT2B has broad substrate specificity with preferences for C16 and LC-PUFAs acyl groups. Moreover, the overexpression of an endogenous DGAT2B resulted in higher lipid yields and enhanced levels of DHA in TAG. Furthermore, a combined overexpression of the endogenous DGAT2B and ectopic expression of a Δ5-elongase showed how iterative metabolic engineering can be used to increase DHA and TAG content, irrespective of nitrogen treatment. Conclusion: This study provides further insight into lipid metabolism in P. tricornutum and suggests a metabolic engineering approach for the efficient production of EPA and DHA in microalgae

Understanding Social and Cultural Factors Associated with Composite Vulnerability to Better Inform Community Intervention Strategies: Cities Changing Diabetes in Houston

We describe a novel procedure for estimating population-level vulnerability to type 2 diabetes and then demonstrate how differences in social and cultural factors among vulnerable sub-groups translate into design considerations for prevention-oriented community interventions. Our study adopted a mixed method approach combining a quantitative evaluation of population data with a qualitative vulnerability assessment that centered around in-depth interviews. Harris County, Texas serves as the setting. Four distinct sub-groups were identified within neighborhoods considered vulnerable to diabetes, based on clinical predictors of diabetes and on economic disadvantage. Differences among these groups were then characterized by their prominent social and cultural factors. Understanding these differences offers a critical refinement important for designing effective local policies and targeted community interventions to prevent type 2 diabetes. This paper emphasizes the qualitative analysis and its implications

Downregulation of SREBP Inhibits Tumor Growth and Initiation by Altering Cellular Metabolism in Colon Cancer

Sterol regulatory element-binding proteins (SREBPs) belong to a family of transcription factors that regulate the expression of genes required for the synthesis of fatty acids and cholesterol. Three SREBP isoforms, SREBP1a, SREBP1c, and SREBP2, have been identified in mammalian cells. SREBP1a and SREBP1c are derived from a single gene through the use of alternative transcription start sites. Here we investigated the role of SREBP-mediated lipogenesis in regulating tumor growth and initiation in colon cancer. Knockdown of either SREBP1 or SREBP2 decreased levels of fatty acids as a result of decreased expression of SREBP target genes required for lipid biosynthesis in colon cancer cells. Bioenergetic analysis revealed that silencing SREBP1 or SREBP2 expression reduced the mitochondrial respiration, glycolysis, as well as fatty acid oxidation indicating an alteration in cellular metabolism. Consequently, the rate of cell proliferation and the ability of cancer cells to form tumor spheroids in suspension culture were significantly decreased. Similar results were obtained in colon cancer cells in which the proteolytic activation of SREBP was blocked. Importantly, knockdown of either SREBP1 or SREBP2 inhibited xenograft tumor growth in vivo and decreased the expression of genes associated with cancer stem cells. Taken together, our findings establish the molecular basis of SREBP-dependent metabolic regulation and provide a rationale for targeting lipid biosynthesis as a promising approach in colon cancer treatment

Departures From Axisymmetric Morphology and Dynamics in Spiral Galaxies

New HI synthesis data have been obtained for six face-on galaxies with the Very Large Array. These data and reanalyses of three additional data sets make up a sample of nine face-on galaxies analyzed for deviations from axisymmetry in morphology and dynamics. This sample represents a subsample of galaxies already analyzed for morphological symmetry properties in the R-band. Four quantitative measures of dynamical nonaxisymmetry are compared to one another and to the quantitative measures of morphological asymmetry in HI and R-band to investigate the relationships between nonaxisymmetric morphology and dynamics. We find no significant relationship between asymmetric morphology and most of the dynamical measures in our sample. A possible relationship is found, however, between morphology and dynamical position angle differences between approaching and receding sides of the galaxy.Comment: 24 pages, 19 figures, AASTeX, accepted for publication in AJ, postscript figures available at ftp://culebra.tn.cornell.edu/pub/david/figures.tar.g