36,979 research outputs found

    Metamorphic fluids and uplift-erosion history of a portion of the Kapuskasing structural zone, Ontario, as deduced from fluid inclusions

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    Fluid inclusions can be used to determine the compositional evolution of fluids present in high grade metamorphic rocks (Touret, 1979) along with the general P-T path followed by the rocks during uplift and erosion (Hollister et al., 1979). In this context, samples of high grade gneisses from the Kapuskasing structural zone (KSZ, Fig. 1) of eastern Ontario were studied in an attempt to define the composition of syn- and post-metamorphic fluids and help constrain the uplift and erosion history of the KSZ. Recent work by Percival (1980), Percival and Card (1983) and Percival and Krogh (1983) shows that the KSZ represents lower crustal granulites that form the lower portion of an oblique cross section through the Archean crust, which was up faulted along a northeast striking thrust fault. The present fluid inclusion study places constraints upon the P-T path which the KSZ followed during uplift and erosion

    Seasonal LAI in slash pine estimated with LANDSAT TM

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    The leaf area index (LAI, total area of leaves per unit area of ground) of most forest canopies varies throughout the year, yet for logistical reasons it is difficult to estimate anything more detailed than a seasonal maximum LAI. To determine if remotely sensed data can be used to estimate LAI seasonally, field measurements of LAI were compared to normalized difference vegetation index (NDVI) values derived using LANDSAT Thematic Mapper (TM) data, for 16 fertilized and control slash pine plots on 3 dates. Linear relationships existed between NDVI and LAI with R(sup 2) values of 0.35, 0.75, and 0.86 for February 1988, September 1988, and March, 1989, respectively. This is the first reported study in which NDVI is related to forest LAI recorded during the month of sensor overpass. Predictive relationships based on data from eight of the plots were used to estimate the LAI of the other eight plots with a root-mean-square error of 0.74 LAI, which is 15.6 percent of the mean LAI. This demonstrates the potential use of LANDSAT TM data for studying seasonal dynamics in forest canopies

    Tropidosteptes forestierae (Hemiptera: Heteroptera: Miridae: Mirinae): a new species of Plant Bug injuring ornamental Florida Swampprivet, Forestiera segregata (Oleaceae), in South Florida

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    The mirine plant bug Tropidosteptes forestierae, new species (Hemiptera: Miridae) is described from Collier County, Florida, where it was found causing serious injury to an extensive ornamental hedge of Florida swampprivet, Forestiera segregata (Jacq.) Krug and Urb. (Oleaceae). Adult male and female, fifth instar, and egg are described. Color images of the adults, nymph, egg, and injury; scanning photomicrographs of selected adult structures; and illustrations of male genitalia are provided. A key to help distinguish the 16 species of Tropidosteptes known to occur in the southeastern United States is given

    Spot activity of the RS CVn star {\sigma} Geminorum

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    We model the photometry of RS CVn star σ\sigma Geminorum to obtain new information on the changes of the surface starspot distribution, i.e., activity cycles, differential rotation and active longitudes. We use the previously published Continuous Periods Search-method (CPS) to analyse V-band differential photometry obtained between the years 1987 and 2010 with the T3 0.4 m Automated Telescope at the Fairborn Observatory. The CPS-method divides data into short subsets and then models the light curves with Fourier-models of variable orders and provides estimates of the mean magnitude, amplitude, period and light curve minima. These light curve parameters are then analysed for signs of activity cycles, differential rotation and active longitudes. We confirm the presence of two previously found stable active longitudes, synchronised with the orbital period Porb=19.60P_{\rm{orb}}=19.60d and find eight events where the active longitudes are disrupted. The epochs of the primary light curve minima rotate with a shorter period Pmin,1=19.47P_{\rm{min,1}}=19.47d than the orbital motion. If the variations in the photometric rotation period were to be caused by differential rotation, this would give a differential rotation coefficient of α0.103\alpha \ge 0.103. The presence of two slightly different periods of active regions may indicate a superposition of two dynamo modes, one stationary in the orbital frame and the other one propagating in the azimuthal direction. Our estimate of the differential rotation is much higher than previous results. However, simulations show that this can be caused by insufficient sampling in our data.Comment: 10 pages, 6 figures. Submitted to A&

    Expression and function of transient receptor potential channels in the female bovine reproductive tract

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    © 2016 Elsevier Inc. The epithelium lining the oviduct is critical for early reproductive events, many of which are mediated via intracellular calcium ions. Despite this, little is known about the regulation of calcium homeostasis in the oviductal epithelium. Epithelial transient receptor potential channels (TRPCs) modulate calcium flux in other tissues, and their expression and functional regulation have therefore been examined using the bovine oviduct as a model for the human. The effects of FSH, LH, 17β-estradiol, and progesterone on TRPCs expression and intracellular calcium flux were determined. Transient receptor potential channels 1, 2, 3, 4, and 6 were expressed in the bovine reproductive tract, and their gene expression varied throughout the estrous cycle. In more detailed studies undertaken on TRPC1 and 6, we show that protein expression varied through the estrus cycle; specifically, 17β-estradiol, FSH, and LH individually and in combination upregulated TRPC1 and 6 expression in cultured bovine oviduct epithelial cells although progesterone antagonized these effects. Functional studies showed changes in calcium mobilization in bovine oviduct epithelial cells were dependent on TRPCs. In conclusion, TRPC1, 2, 3, 4, and 6 are present in the epithelium lining the bovine oviduct, and TRPC1 and 6 vary through the estrous cycle suggesting an important role in early reproductive function

    Evaluation of directionally solidified eutectic superalloys for turbine blade applications

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    Alloys from the following systems were selected for property evaluation: (1) gamma/gamma-Mo (Ni-base, rods of Mo); (2) gamma-beta (Ni-base, lamellae or rods of (Ni, Fe/Co Al); and (3) gamma-gamma (Ni-base rods of Ni3Al gamma). The three alloys were subjected to longitudinal and transverse tensile and rupture tests from 750 C to 1100 C, longitudinal shear strength was measured at several temperatures, resistance to thermal cycling to 1150 C was determined, cyclic oxidation resistance was evaluated at 750 C and 1100 C, and each system was directionally solidified in an alumina shell mold turbine shape to evaluate mold/metal reactivity. The gamma/gamma Mo system has good rupture resistance, transverse properties and processability, and is a high potential system for turbine blades. The gamma-beta system has good physical properties and oxidation resistance, and is a potential system for turbine vanes. The gamma-gamma system has good high temperature rupture resistance and requires further exploratory research
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