1,063 research outputs found

    A mineral reconnaissance survey of the Abington-Biggar-Moffat-area, south-central Scotland

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    Panned heavy mineral concentrates, mostly obtained from stream sediments, were collected from 195 sites in the Abington-Biggar-Moffat area. The project area, which lies immediately east of the formerly important mining district of Wanlockhead-Leadhills, covers approximately 500 km2 of the north-central sector of the Southern Uplands. It incorporates the Hart Fell range of hills, the headwaters catchment for the River Tweed and River Annan, some tributaries of the River Clyde, and, to the east, the Culter Water, Talla Reservoir, Megget Water and the head of the Ettrick valley. Numerous new occurrences of lead, zinc, copper and barium minerals were found and nine areas are recommended for further investigation. Minor amounts of baryte and traces of cupriferous pyrite were identified in the basal breccia of the-New Red Sandstone deposits in Annandale. The mercury mineral, cinnabar, was identified for the first time in Scotland, occurring in trace amounts in stream sediment concentrates in the Coulter area close to the Southern Upland Fault. Chromiferous spine1 was recognised as a major constituent in the majority of panned samples. It is present as a detrital mineral in greywackes but must have been originally derived from ultrabasic rocks. An unusual mineral widely dispersed in trace amounts is corundum (including some gem-quality sapphire). Historical references (Lauder Lindsay, 1868-9, 1871) to a wide distribution for particle gold were confirmed and many new occurrences found. A local provenance for the element is now considered certain. Some placer concentration of gold and chromiferous spine1 is likely in the alluvium of the valleys of the River Tweed and the Megget Water. Six greywacke formations, previously defined in other parts of the Southern Uplands, were mapped in the project area, each distinguished by a characteristic lithology and heavy mineral content

    The EBV-encoded latent membrane proteins, LMP2A and LMP2B, limit the actions of interferon by targeting interferon receptors for degradation

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    Although frequently expressed in Epstein–Barr virus (EBV)-positive malignancies, the role that latent membrane protein 2A and 2B (LMP2A and LMP2B) have in the oncogenic process remains obscure. Here we show a novel function for these proteins in epithelial cells, namely, their ability to modulate signalling from type I/II interferon receptors (IFNRs). We show that LMP2A- and LMP2B-expressing epithelial cells show decreased responsiveness to interferon (IFN)α and IFNγ, as assessed by STAT1 phosphorylation, ISGF3 and GAF-mediated binding to IFN-stimulated response element and IFNγ-activated factor sequence elements and luciferase reporter activation. Transcriptional profiling highlighted the extent of this modulation, with both viral proteins impacting ‘globally’ on IFN-stimulated gene expression. Although not affecting the levels of cell-surface IFNRs, LMP2A and LMP2B accelerated the turnover of IFNRs through processes requiring endosome acidification. This function may form part of EBV's strategy to limit anti-viral responses and define a novel function for LMP2A and LMP2B in modulating signalling from receptors that participate in innate immune responses

    Active-matrix GaN micro light-emitting diode display with unprecedented brightness

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    Displays based on microsized gallium nitride light-emitting diodes possess extraordinary brightness. It is demonstrated here both theoretically and experimentally that the layout of the n-contact in these devices is important for the best device performance. We highlight, in particular, the significance of a nonthermal increase of differential resistance upon multipixel operation. These findings underpin the realization of a blue microdisplay with a luminance of 10⁶ cd/m²

    Allometric analysis of the giraffe cardiovascular system

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    There has been co-evolution of a long neck and high blood pressure in giraffes. How the cardiovascular system (CVS) has adapted to produce a high blood pressure, and how it compares with other similar sized mammals largely is unknown. We have measured body mass and heart structure in 56 giraffes of both genders ranging in body mass from 18 kg to 1500 kg, and developed allometric equations that relate changes in heart dimensions to growth and to cardiovascular function. Predictions made from these equations match measurements made in giraffes. We have found that heart mass increases as body mass increases but it has a relative mass of 0.51±0.7% of body mass which is the same as that in other mammals. The left ventricular and interventricular walls are hypertrophied and their thicknesses are linearly related to neck length. Systemic blood pressure increases as body mass and neck length increase and is twice that of mammals of the same body mass. Cardiac output is the same as, but peripheral resistance double that predicted for similar sized mammals. We have concluded that increasing hydrostatic pressure of the column of blood during neck elongation results in cardiac hypertrophy and concurrent hypertrophy of arteriole walls raising peripheral resistance, with an increase in blood pressure following.The Bubye Valley Conservancy, Zimbabwe and the Don Craib Trust (JDS), from a personal research grant (JDS) and the University of Wyoming (GM).http://www.elsevier.com/locate/cbpamn201

    Effect of logic family on radiated emissions from digital circuits

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    Radiated emissions were measured for simple digital circuits designed to operate with various logic families. Emissions in the near and far field were found to depend both on the circuit layout and the choice of logic family. However, the difference in peak emissions between any two logic families was found to be independent of circuit layout. The greatest difference in peak emissions was between high-speed 74ACT logic and low-speed 4000 CMOS logic devices, with a mean value of approximately 20 dB. Emissions from a more complex circuit were compared with the measurements on simple loop circuits. Test circuits were used to measure the propagation delay, the rise and fall times, the maximum operating frequency and the transient switching currents between two successive logic gates for each logic family. Empirical formulas have been derived that relate relative peak emissions to these switching parameters. It is hoped that these will assist designers to assess the effect of choice of logic family on electromagnetic compatibility

    Kinematical Limits on Higgs Boson Production via Gluon Fusion in Association with Jets

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    In this paper, we analyze the high-energy limits for Higgs boson plus two jet production. We consider two high-energy limits, corresponding to two different kinematic regions: a) the Higgs boson is centrally located in rapidity between the two jets, and very far from either jet; b) the Higgs boson is close to one jet in rapidity, and both of these are very far from the other jet. In both cases the amplitudes factorize into impact factors or coefficient functions connected by gluons exchanged in the t channel. Accordingly, we compute the coefficient function for the production of a Higgs boson from two off-shell gluons, and the impact factors for the production of a Higgs boson in association with a gluon or a quark jet. We include the full top quark mass dependence and compare this with the result obtained in the large top-mass limit.Comment: 35 pages, 6 figure

    Demography of giraffe deaths in a drought

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    Darwin’s theory for the evolution of the long neck of giraffes is that height confers access to browse free of competition from smaller browsers. The theory predicts that survivors of a drought will be the tallest animals in a population. All studies so far have tested this hypothesis by analysis of feeding patterns and behaviour.We have studied it by analysing the demography of deaths in a drought. Using skeletal material from 26 giraffes that died as a result of a drought in southeastern Zimbabwe in 2008, we established the body mass, height, and age of the dead giraffes using allometric equations developed from culled animals. Typical giraffe populations consist of 55% adults (>6 years old), 15% young adults (3–6 years old), 15% juveniles (1–3 years old), and 15% neonates (<1 year old). Skeletons came from 54% adults, 14% young adults, and 32% juveniles. No neonatal skeletons were found. More juveniles died than expected because they have to compete with other browsers for nutrients. Most adult deaths occurred in the tallest and largest males because their daily requirements for browse are highest and could not be met by the amounts available at any level. Thus the survivors of this drought were young adults, a finding contrary to the predictions of Darwin’s feeding hypothesis.The Don Craib Trust (JDS), the University of Wyoming (GM), and the University of Pretoria (SvS).http://www.informaworld.commn201

    Nematodes of the small intestine of African buffaloes, Syncerus caffer, in the Kruger National Park, South Africa

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    The abundance and distribution of parasitic helminths in populations of African buffaloes, Syncerus caffer, have not been well documented. A total of 28 buffaloes of different ages and sexes were sampled in the Kruger National Park, South Africa, for nematodes of the small intestine. Three nematode species were identified, namely Cooperia fuelleborni, Cooperia hungi and Trichostrongylus deflexus, with C. hungi being a new country record for African buffalo in South Africa. The overall prevalence was 71% and the average number of worms was 2346 (range: 0–15 980). This is a small burden for such a large mammal. Sex, age and body condition of the buffaloes had no significant effect on worm occurrence.http://www.ojvr.orgam2013ab201

    Structurally integrated transmitter beacon for underwater wireless optical communications in multiple ocean types

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    In this paper we describe a structurally integrated optical transmitter beacon concept that consists of a side-scattering fiber that can conform to solid surfaces, such as the outer surface of a submersible Remotely Operated Vehicle (ROV), suitable for convenient deployment in underwater applications. By coupling a modulated optical signal from a laser diode into the fiber, an omnidirectional "beacon" is achieved. We demonstrate coarse Wavelength Division Multiplexing (WDM), illustrating that these beacons can transmit optical wireless data through several attenuation lengths in turbid water at aggregate data rates of up to 20 Mb/s
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