1,629 research outputs found

    Patterns of variation in the climates, soils and vegetation of some subantarctic and antarctic islands

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    Patterns of variation in the climate, soils and vegetation among 19 sites from 3 subantarctic and one maritime antarctic island were defined by principal component analyses (PCA) of abiotic and vegetation variables. The sites were classified on the same parameters by nearest neighbour/group mean clustering. The first two components from the PCA of the abiotic (climate and soil) data separated the islands along a climatic gradient, partly related to latitude. Sites within each island were separated along parallel series by edaphic factors and exposure. The third and fourth components reflected changes in soil chemistry caused by manuring by seabirds and seals. Cluster analysis on the abiotic variables showed that the main division was between high- and low-latitude islands, with a strong tendency to ‘chaining’. PCA of the vegetation data resulted in few conspicuous or simple patterns but three environmental trends were indicated, which corresponded approximately to components II, III and IV from the PCA of the abiotic data. Animal manuring induces vegetation successions parallel to the soil changes noted in the abiotic analyses and these combine with radiative successions from fellfields to all other vegetation types to produce a complex, and somewhat ambiguous, pattern of sites. Cluster analyses on the botanical variables produced clear groupings but these varied markedly according to the life-form category used to classify two of the plant species. This instability reflects the wide ecological amplitude of the phanerogamic species, with single species often filling what would be a variety of niches in less isolated ecosystems. The results also emphasize the importance of bryophytes on the southern subpolar islands. The two sets of analyses, taken together, emphasize the special characteristics of subantarctic islands found in previous bipolar comparisons and also indicate the extreme sensitivity of these ecosystems to the introduction of alien species

    EFFECTS OF JOINT PRODUCT MANAGEMENT STRATEGIES ON E.COLI 0157:H7 AND FEEDLOT PROFITS

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    The objective of this study was to determine the effect of Escherichia coli 0157:H7 on feedlot profits. Fecal samples from 711 feedlot pens in 73 feedlots in Nebraska, Kansas, Oklahoma, and Texas were tested for E. coli 0157:H7. Average daily gain and feed-to-gain ratios were computed for each feedlot pen, and managers from each feedlot provided information on various feedlot management practices. Cattle performance and E. coli 0157:H7 prevalence are both affected by feedlot management practices. The indirect effect of E. coli 0157:H7 on potential feedlot profits was determined by measuring the effects of management practices on E. coli 0157:H7 levels and cattle performance. Management practices that affect cattle performance were identified using ordinary least squares regressions. A negative binomial regression was used to identify management practices that affect E. coli 0157:H7 prevalence. Certain feedlot management practices were identified that have a joint impact on cattle performance and E. coli 0157:H7 prevalence. Using predatory insects to control flies, controlling for stray dogs, foxes, and coyotes in feed areas, removing manure from pens during finishing, and including tallow in the ration were management strategies associated with higher feedlot profits and lower E. coli 0157:H7 prevalence. Using mobile sprinklers for dust control and including alfalfa or sorghum hay or silage in the ration were associated with lower E. coli 0157:H7 prevalence and lower feedlot profits. Increasing days between cleaning water tanks and restricting movement of horses were associated with higher feedlot profits and higher E. coli 0157:H7 levels. Controlling for stray cats in feed areas and including liquid protein in the ration were associated with lower feedlot profits and higher E. coli 0157:H7 levels. These specific management strategies, which were not robust through a sensitivity analysis, should be interpreted with caution. The general categories of management strategies, however, were robust and consistent with past researchLivestock Production/Industries,

    First-principles Calculation of the Formation Energy in MgO-CaO Solid Solutions

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    The electronic structure and total energy were calculated for ordered and disordered MgO-CaO solid solutions within the multiple scattering theory in real space and the local density approximation. Based on the dependence of the total energy on the unit cell volume the equilibrium lattice parameter and formation energy were determined for different solution compositions. The formation energy of the solid solutions is found to be positive that is in agreement with the experimental phase diagram, which shows a miscibility gap.Comment: 11 pages, 3 figure

    Tuning gaps and phases of a two-subband system in a quantizing magnetic field

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    In this work we study the properties of a two-subband quasi-two-dimensional electron system in a strong magnetic field when the electron filling factor is equal to four. When the cyclotron energy is close to the intersubband splitting the system can be mapped onto a four-level electron system with an effective filling factor of two. The ground state is either a ferromagnetic state or a spin-singlet state, depending on the values of the inter-level splitting and Zeeman energy. The boundaries between these phases are strongly influenced by the inter-electron interaction. A significant exchange-mediated enhancement of the excitation gap results in the suppression of the electron-phonon interaction. The rate of absorption of non-equilibrium phonons is calculated as a function of Zeeman energy and inter-subband splitting. The phonon absorption rate has two peaks as a function of intersubband splitting and has a step-like structure as a function of Zeeman energy

    Standardisation of RTS beverage from reconstituted cashew apple-based blended juice powder along with Sugandi

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    Cashew has commercial value for its nut and peduncle (false fruit), known as cashew apple. Requirements of consumers considering convenience, food safety, health benefits and sensory quality have increased demand for fruit juices, but most consumers don’t get time for the ready to use products. Instant juice powders can meet consumer requirements being cheap to transport and with prolonged shelf life. Then the blended juice was mixed with maltodextrin @15 per cent, i.e., 15 g for 100 mL of blended juice by proper homogenisation. The roots of the sugandi (Swallow root - Decalepsis hamiltonii) were collected, cleaned thoroughly and discarded the central white portion of the roots. Among the blended juice treatment combinations, the highest pH of 3.45 was recorded in B3 (75% cashew apple juice + 25% pineapple juice powder at 150°C inlet temperature with a flow rate of 10 mL min-1). The ready-to-serve (RTS) beverage, along with sugandi stored under refrigerated condition, were free from microbial proliferation till the end of the storage period (60th day of storage), indicating its fitness for consumption with maximum flavour, taste and overall acceptability

    Detection of Atmospheric Cherenkov Radiation Using Solar Heliostat Mirrors

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    The gamma-ray energy region between 20 and 250 GeV is largely unexplored. Ground-based atmospheric Cherenkov detectors offer a possible way to explore this region, but large Cherenkov photon collection areas are needed to achieve low energy thresholds. This paper discusses the development of a Cherenkov detector using the heliostat mirrors of a solar power plant as the primary collector. As part of this development, we built a prototype detector consisting of four heliostat mirrors and used it to record atmospheric Cherenkov radiation produced in extensive air showers created by cosmic ray particles.Comment: 16 latex pages, 8 postscript figures, uses psfig.sty, to be published in Astroparticle Physic

    Application of Pulsed Field Gel Electrophoresis to Determine Îł-ray-induced Double-strand Breaks in Yeast Chromosomal Molecules

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    The frequency of DNA double-strand breaks (dsb) was determined in yeast cells exposed to Îł-rays under anoxic conditions. Genomic DNA of treated cells was separated by pulsed field gel electrophoresis, and two different approaches for the evaluation of the gels were employed: (1) The DNA mass distribution profile obtained by electrophoresis was compared to computed profiles, and the number of DSB per unit length was then derived in terms of a fitting procedure; (2) hybridization of selected chromosomes was performed, and a comparison of the hybridization signals in treated and untreated samples was then used to derive the frequency of dsb

    Effects of Anomalous Magnetic Moment in the Quantum Motion of Neutral Particle in Magnetic and Electric Fields Produced by a Linear Source in a Conical Spacetime

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    In this paper we analyse the effect of the anomalous magnetic moment on the non-relativistic quantum motion of a neutral particle in magnetic and electric fields produced by linear sources of constant current and charge density, respectively.Comment: 17 pages, no figur

    Predicting the effect of radiation damage on dark current in a space-qualified high performance CMOS image sensor

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    The CIS115 is a Teledyne-e2v CMOS image sensor with 1504 × 2000 pixels of 7 ÎŒm pitch. It has a high optical quantum efficiency owing to a multi-layer anti-reflective coating and its backside illuminated construction, and low dark current due to its pinned photodiode 4T pixel architecture. The sensor operates in rolling shutter mode with a frame rate of up to 7.5 fps (if using the whole array), and has a low readout noise of ~5 electrons rms. The CIS115 has been selected for use within the JANUS instrument, which is a high resolution camera due to launch on board ESA's JUpiter ICy moons Explorer (JUICE) spacecraft in 2022. After an interplanetary transit time of over 7 years, JUICE will spend 3.5 years touring the Jovian system, studying three of the Galilean moons in particular: Ganymede, Callisto and Europa. During this latter part of the mission, the spacecraft and hence the CIS115 sensor will be subjected to the significant levels of trapped radiation surrounding Jupiter. Gamma and proton irradiation campaigns have therefore been undertaken in order to evaluate both ionising and non-ionising dose effects on the CIS115's dark current performance. Characterisations were carried out at expected mission operating temperatures (−35 ± 10oC) both prior to and post-irradiation. Models of the resulting degradation in dark current behaviour will be combined with expected doses during the JUICE mission in order to predict the performance of the CIS115 at the mission end-of-lif
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