2,071 research outputs found

    SEQUAL 2.1 User’s Manual

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    SEQUAL is a device simulation program which performs a quantum mechanical analysis of electron transport. The user need not be an expert in quantum mechanics to obtain useful results from this program, although an understanding of the subject is an invaluable aid in the interpretation of output. For this reason,, the theoretical formulation of the analysis is presented in some detail, following a brief introduction. The knowledgeable (or anxious) user may turn directly to the discussions of input and output in Chapters 3 and 4. The reader is cautioned, however, not to skip Chaper 2 entirely. At the heart of many a program error\u27 lies a misinterpretation of output

    Chapman-Enskog expansion about nonequilibrium states: the sheared granular fluid

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    The Chapman-Enskog method of solution of kinetic equations, such as the Boltzmann equation, is based on an expansion in gradients of the deviations fo the hydrodynamic fields from a uniform reference state (e.g., local equilibrium). This paper presents an extension of the method so as to allow for expansions about \emph{arbitrary}, far-from equilibrium reference states. The primary result is a set of hydrodynamic equations for studying variations from the arbitrary reference state which, unlike the usual Navier-Stokes hydrodynamics, does not restrict the reference state in any way. The method is illustrated by application to a sheared granular gas which cannot be studied using the usual Navier-Stokes hydrodynamics.Comment: 23 pages, no figures. Submited to PRE Replaced to correct misc. errors Replaced to correct misc. errors, make notation more consistant, extend discussio

    Importance of Space-Charge Effects in Resonant Tunneling Devices

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    The consideration of space charge in the analysis of resonant tunneling devices leads to a substantial modification of the current-voltage relationship. The region of negative differential resistance (NDR) is shifted to a higher voltage, and broadened along the voltage axis. Moreover, the peak value of current prior to NDR is reduced, leading to a reduction in the predicted peak-to-valley ratio. An approach is presented to include space-charge effects, and a recently fabricated GaAs-Alx Gal _ x As structure is analyzed, to underscore the importance of a self-consistent electrostatic potential in theoretical calculations

    Assessing the Use of Molecular Barcoding and qPCR for Investigating the Ecology of Prorocentrum minimum (Dinophyceae), a Harmful Algal Species

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    Prorocentrum minimum is a species of marine dinoflagellate that occurs worldwide and can be responsible for harmful algal blooms (HABs). Some studies have reported it to produce tetrodotoxin; however, results have been inconsistent. qPCR and molecular barcoding (amplicon sequencing) using high-throughput sequencing have been increasingly applied to quantify HAB species for ecological analyses and monitoring. Here, we isolated a strain of P. minimum from eastern Australian waters, where it commonly occurs, and developed and validated a qPCR assay for this species based on a region of ITS rRNA in relation to abundance estimates from the cultured strain as determined using light microscopy. We used this tool to quantify and examine ecological drivers of P. minimum in Botany Bay, an estuary in southeast Australia, for over ~14 months in 2016-2017. We compared abundance estimates using qPCR with those obtained using molecular barcoding based on an 18S rRNA amplicon. There was a significant correlation between the abundance estimates from amplicon sequencing and qPCR, but the estimates from light microscopy were not significantly correlated, likely due to the counting method applied. Using amplicon sequencing, ~600 unique actual sequence variants (ASVs) were found, much larger than the known phytoplankton diversity from this region. P. minimum abundance in Botany Bay was found to be significantly associated with lower salinities and higher dissolved CO2 levels

    Integrated fish stock assessment and monitoring program

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    Humidity-induced phase transitions of ferric sulfate minerals studied by in situ and ex situ X-ray diffraction

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    Phases encountered in the hydration of monoclinic and trigonal anhydrous Fe2(SO4)3 and evaporation of Fe2(SO4)3 solutions at room temperature were determined using in situ and ex situ X-ray diffraction (XRD) under dynamic relative humidity (RH) control at room temperature (22–25 °C). Both monoclinic and trigonal forms of Fe2(SO4)3 remain anhydrous at 11% RH or below, and undergo the following phase evolution sequence: anhydrous Fe2(SO4)3 → (ferricopiapite, rhomboclase) → kornelite → paracoquimbite at RH between 33 and 53% as a function of time. Evaporation of aqueous Fe2(SO4)3 solutions at 40% < RH < 60% results in precipitation of ferricopiapite and rhomboclase during evaporation, followed by a transition to kornelite and then paracoquimbite. Evaporation at RH < 33% produced an amorphous ferric-sulfate phase. The presence of some iron sulfate hydrates and their stability under varying RH are not only determined by the final humidity level, but also the intermediate stages and hydration history (i.e., either ferricopiapite or paracoquimbite can be a stable phase at 62% RH depending on the hydration history). The sensitivity to humidity change and path-dependent transitions of ferric sulfates make them potentially valuable indicators of paleo-environmental conditions and past water activity on Mars. The phase relationships reported herein can help in understanding the diagenesis of ferric sulfate minerals, and are applicable to geochemical modeling of mineral solubility in multi-component systems, an endeavor hindered by the need for fundamental laboratory studies of iron sulfate hydrates

    Reasons why nurses decline influenza vaccination: a qualitative study

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    To explore reasons of non-vaccinated nursing staff for declining seasonal influenza vaccination. The annual influenza vaccination of healthcare workers reduces morbidity and mortality among vulnerable patients. Still, vaccination rates remain very low, particularly in nursing staff. While several studies have explored barriers for healthcare workers to get vaccinated, most have used a quantitative approach.; Data were collected by in-depth individual semi-structured interviews with 18 nurses from a range of fields, positions in organizational hierarchy, work experience and hospitals in two German-speaking cantons in Switzerland. Interviews were transcribed and analysed using conventional content analysis.; Three interconnected themes explaining why nurses decline influenza vaccination were identified: Firstly, the idea of maintaining a strong and healthy body, which was a central motif for rejecting the vaccine. Secondly, the wish to maintain decisional autonomy - especially over one's body and health. Thirdly, nurses' perception of being surrounded by an untrustworthy environment, which restricts their autonomy and seemingly is in opposition to their goal of maintaining a strong and healthy body.; Nurses tend to rely on conventional health beliefs rather than evidence based medicine when making their decision to decline influenza vaccination. Interventions to increase influenza vaccination should be tailored specifically for nurses. Empowering nurses by promoting decision-making skills and by strengthening their appraisal may be important factors to consider when planning future interventions to improve vaccination rates. The teaching of evidence-based decision-making should be integrated on different levels, including nurses' training curricula, their workspace and further education

    Nonequilibrium Microscopic Distribution of Thermal Current in Particle Systems

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    A nonequilibrium distribution function of microscopic thermal current is studied by a direct numerical simulation in a thermal conducting steady state of particle systems. Two characteristic temperatures of the thermal current are investigated on the basis of the distribution. It is confirmed that the temperature depends on the current direction; Parallel temperature to the heat-flux is higher than antiparallel one. The difference between the parallel temperature and the antiparallel one is proportional to a macroscopic temperature gradient.Comment: 4 page

    Quantification Of The Efficiency Of Rumen Microbial Protein Synthesis In Steers Fed Green Tropical Grass

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    The rate of rumen microbial crude protein (MCP) supply to the intestines is a crucial element in the current rumen models to predict respond of ruminants to a certain diet. Data from tropical pastures always below predicted results from the existing rumen models. Thus, quantification of the rumen MCP supply from tropical grass will improve predictive rate under tropical feeding conditions. Four Brahman crossbred steers (457±20.1 kg) were used in a metabolism study. Pangola grass (Digitaria erianthe cv. Steudal) was harvested every morning and fed to the animals soon after. Parameters measured were EMPS, intake, fractional passage rates, and rumen ammonia concentration. The EMPS was estimated using purine derivative excretion in urine. Crude protein and water soluble carbohydrates content were 6.3 and 7.4% of dry matter (DM) respectively. DM intake was 1.6% live weight. Average rumen ammonia concentration was 69 mg/L whilst rumen passage rates were 7.84 and 6.92 %/h for fluid and solids respectively. EMPS was only 72 g MCP/kg digestible organic matter. It might be concluded that EMPS in steers consuming green pangola grass was below the minimum level for forage diets adopted in the current feeding standards
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