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Average Slope (average + slope)
Selected AbstractsDental topography and diets of four old world monkey speciesAMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2009Jonathan M. Bunn Abstract Dental topographic analysis allows comparisons of variably worn teeth within and between species to infer relationships between dental form and diet in living primates, with implications for reconstructing feeding adaptations of fossil forms. Although analyses to date have been limited mainly to the M2s of a few primate taxa, these suggest that dental topographic analysis holds considerable promise. Still, larger samples including a greater range of species and different tooth types are needed to determine the potential of this approach. Here we examine dental topography of molar teeth of Cercocebus torquatus (n=48), Cercopithecus campbelli (n=50), Colobus polykomos (n=50), and Procolobus badius (n=50). This is the first such study of large samples of Old World monkeys, and the first to include analyses of both M1s and M2s. Average slope, relief, and surface angularity were computed and compared among tooth types, wear stages, and species. Results suggest that (1) data for M1s and M2s cannot be compared directly; (2) slope and relief decline with wear on M2s of all taxa, and M1s of the colobines, whereas angularity does not generally change except in the most worn specimens; and (3) folivorous colobines tend to have more sloping surfaces and more relief than do frugivorous cercopithecines, though angularity does not clearly separate taxa by diet. Am. J. Primatol. 71:466,477, 2009. © 2009 Wiley-Liss, Inc. [source] Differential Ca2+ -dependence of transmitter release mediated by P/Q- and N-type calcium channels at neonatal rat neuromuscular junctionsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2002Marcelo D. Rosato-Siri Abstract N- and P/Q-type voltage dependent calcium channels (VDCCs) mediate transmitter release at neonatal rat neuromuscular junction (NMJ). Thus the neonatal NMJ allows an examination of the coupling of different subtypes of VDCCs to the release process at a single synapse. We studied calcium dependence of transmitter release mediated by each channel by blocking with ,-conotoxin GVIA the N-type channel or with ,-agatoxin IVA the P/Q-type channel while changing the extracellular calcium concentration ([Ca2+]o). Transmitter release mediated by P/Q-type VDCCs showed steeper calcium dependence than N-type mediated release (average slope 3.6 ± 0.09 vs. 2.6 ± 0.03, respectively). Loading the nerve terminals with 10 µm BAPTA-AM in the extracellular solution reduced transmitter release and occluded the blocking effect of ,-conotoxin GVIA (blockade ,2 ± 9%) without affecting the action of ,-agatoxin IVA (blockade 85 ± 4%). Both VDCC blockers were able to reduce the amount of facilitation produced by double-pulse stimulation. In these conditions facilitation was restored by increasing [Ca2+]o. The facilitation index (fi) was also reduced by loading nerve terminals with 10 µm BAPTA-AM (fi = 1.2 ± 0.1). The control fi was 2.5 ± 0.1. These results show that P/Q-type VDCCs were more efficiently coupled to neurotransmitter release than were N-type VDCCs at the neonatal neuromuscular junction. This difference could be accounted for by a differential location of these channels at the release site. In addition, our results indicate that space,time overlapping of calcium domains was required for facilitation. [source] Catchment-scale contribution of forest roads to stream exports of sediment, phosphorus and nitrogenHYDROLOGICAL PROCESSES, Issue 23 2007Gary J. Sheridan Abstract The relative contribution of forest roads to total catchment exports of suspended sediment, phosphorus, and nitrogen was estimated for a 13 451 ha forested catchment in southeastern Australia. Instrumentation was installed for 1 year to quantify total in-stream exports of suspended sediment, phosphorus, and nitrogen. In addition, a total of 101 road,stream crossings were mapped and characterized in detail within the catchment to identify the properties of the road section where the road network and the stream network intersect. Sediment and nutrient generation rates from different forest road types within the catchment were quantified using permanent instrumentation and rainfall simulation. Sediment and nutrient generation rates, mapped stream crossing information, traffic data and annual rainfall data were used to estimate annual loads of sediment, phosphorus, and nitrogen from each stream crossing in the catchment. The annual sum of these loads was compared with the measured total catchment exports to estimate the proportional contribution of loads from roads within the catchment. The results indicated that 3·15 ha of near-stream unsealed road surface with an average slope of 8·4% delivered an estimated 50 t of the 1142 t of total suspended sediment exported from the catchment, or about 4·4% of the total sediment load from the forest. Stream discharge over this period was 69 573 Ml. The unsealed road network delivered an estimated maximum of 22 kg of the 1244 kg of total phosphorus from the catchment, or less than 1·8% of the total load from the forest. The average sediment and phosphorous load per crossing was estimated at 0·5 t (standard deviation 1·0 t) and 0·22 kg (standard deviation 0·30 kg) respectively. The lower proportional contribution of total phosphorus resulted from a low ratio of total phosphorus to total suspended sediment for the road-derived sediment. The unsealed road network delivered approximately 33 kg of the 20 163 kg of total nitrogen, about 0·16% of the total load of nitrogen from the forest. The data indicate that, in this catchment, improvement of stream crossings would yield only small benefits in terms of net catchment exports of total suspended sediment and total phosphorus, and no benefit in terms of total nitrogen. These results are for a catchment with minimal road-related mass movement, and extrapolation of these findings to the broader forested estate requires further research. Copyright © 2007 John Wiley & Sons, Ltd. [source] SENSITIVITY CONSIDERATIONS WHEN MODELING HYDROLOGIC PROCESSES WITH DIGITAL ELEVATION MODEL,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2001Sung-Mm Cho ABSTRACT: The purpose of this paper is to investigate the sensitivity of a hydrologic models to the type of DEM used. This was done while modeling basin water quality with 1:24,000 and 1:250,000 U.S. Geological Survey DEMs as input to model hydrological processes. The manner in which the model results were sensitive to the choice of raster cell size (scale) is investigated in this study. The Broadhead watershed, located in New Jersey, USA, was chosen as a study area. Curve numbers were estimated by a trial and error to match simulated and observed total discharge. Monthly runoff for the watershed was used in the calibration process. Higher runoff volumes were simulated by the model when the 1:24,000 DEM were used as input data, probably due to the finer resolution which simulated increased average slope and hence higher estimated runoff from the watershed. As the simulated slope of the watershed is flatten with the 1:250,000 DEM, the response of stream flow was delayed and simulated less runoff volume. (KEY TERMS: DEM; curve number; sensitivity analysis; runoff volume; water quality; calibration.) [source] Haze of polyethylene films,effects of material parameters and clarifying agentsPOLYMER ENGINEERING & SCIENCE, Issue 5 2002Erik Andreassen Effects of material parameters on the haze of blown films were analyzed. Four linearlow-density polyethylenes (two metallocene grades and two Ziegler-Natta grades) were studied in combination with three additives (two sorbitol-based clarifying agents and a low-molecular-weight long-chain branched polyethylene). One of the sorbitol-based additives reduced the haze of both the metallocene materials in this study, but did not have any positive effect on the two Ziegler-Natta materials. The variation in haze among the four base materials was directly related to the root-mean-square surface roughness (,). When considering all 16 material/additive combinations, the link between haze and surface topography was not a simple ,-haze relationship, but the haze was correlated with the average distance between adjacent surface profile peaks, the average slope, and the power spectral density at high lateral frequencies. Both of the mechanisms referred to in the literature, extrusion-induced haze and crystallization-induced haze, were probably active for the films in this study. [source] 4336: Acute mechanical effect of riboflavin corneal cross-linkingACTA OPHTHALMOLOGICA, Issue 2010A PENNOS Purpose To study the acute mechanical effect of corneal cross-linking in vitro. Methods Twenty porcine eyes were harvested from a local abattoire. The epithelium was removed using a rotating brush and corneal buttons having diameter of 8 mm were excised using a Barron's PKP trephine. The buttons were left immersed for four hours in Dextran solution (20%W/V) in order to regulate their hydration. The buttons were immersed in riboflafin 0.1% in dextran 20% and separated in two groups (10 buttons each) where one group was irradiated for 30 minutes with UV light while the other group was not irradiated and served as control. After treatment mechanical measurements were performed by means of a purposely-developed device featuring a stepping motor and a load cell. The motor shaft has a spherical tip that compresses the corneal button against a flat surface mounted on the load cell. The slope of force versus normalized deformation was recorded for each specimen. Results The control group had an average slope of 3.55 (± 1.81) while the irradiated group had 4.47 (±1.80). This difference was not statistically significant. (p=0.27) Conclusion This compressibility test did not reveal statistically significant changes between the two groups immediately after UV corneal cross-linking. It remains to be elucidated whether different tests (e.g. elongation) may yield different results. 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