33,625 research outputs found

    Relative decompression risks of spacecraft cabin atmospheres

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    Relative decompression risk studies of spacecraft cabin atmosphere using miniature pig

    A critical appraisal of WinEcon and its use in a first‐year undergraduate Economics programme

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    This is an extended review of WinEcon, a CAL package for introductory economics. Our comments are based on a survey of staff and students involved in the first large‐scale (n = 300+) attempt to integrate WinEcon into a teaching and assessment programme

    Electric field induced charge noise in doped silicon: ionization of phosphorus donors

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    We report low frequency charge noise measurement on silicon substrates with different phosphorus doping densities. The measurements are performed with aluminum single electron transistors (SETs) at millikelvin temperatures where the substrates are in the insulating regime. By measuring the SET Coulomb oscillations, we find a gate voltage dependent charge noise on the more heavily doped substrate. This charge noise, which is seen to have a 1/f spectrum, is attributed to the electric field induced tunneling of electrons from their phosphorus donor potentials.Comment: 4 page, 3 figure

    Unlimited simultaneous discrimination intervals in regression Technical report no. 90

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    Unlimited simultaneous discrimination intervals in linear regression

    Mean curvature flow in a Ricci flow background

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    Following work of Ecker, we consider a weighted Gibbons-Hawking-York functional on a Riemannian manifold-with-boundary. We compute its variational properties and its time derivative under Perelman's modified Ricci flow. The answer has a boundary term which involves an extension of Hamilton's Harnack expression for the mean curvature flow in Euclidean space. We also derive the evolution equations for the second fundamental form and the mean curvature, under a mean curvature flow in a Ricci flow background. In the case of a gradient Ricci soliton background, we discuss mean curvature solitons and Huisken monotonicity.Comment: final versio

    Rural environmental concern: Effects of position, partisanship and place

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    The social bases of environmental concern in rural America resemble those for the nation as a whole, but also reflect the influence of place. Some general place characteristics, such as rates of population growth or resource-industry employment, predict responses across a number of environmental issues. Other unique or distinctive aspects of local society and environment matter as well. We extend earlier work on both kinds of place effects, first by analyzing survey data from northeast Oregon. Results emphasize that “environmental concern” has several dimensions. Second, we contextualize the Oregon results using surveys from other regions. Analysis of an integrated dataset (up to 12,000 interviews in 38 U.S. counties) shows effects from respondent characteristics and political views, and from county rates of population growth and resource-based employment. There also are significant place-to-place variations that are not explained by variables in the models. To understand some of these we return to the local scale. In northeast Oregon, residents describe how perceptions of fire danger from unmanaged forest lands shape their response to the word conservation. Their local interpretation contrasts with more general and urban connotations of this term, underlining the importance of place for understanding rural environmental concern

    The Microstructure of the Hen\u27s Egg Shell - A Short Review

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    The structure of the hen\u27s egg shell can be divided into five separate layers . The Innermost layer consists of two distinct membranes known as the inner and outer shell membranes. These membranes are compos ed of networks of protein/polysaccharide fibres and are =70 mm thick. Attached to the outer fibres of the outer membrane are polycrystals of calcite (calcium carbonate) which extend outward in an inverse conical manner until the cones from several sites of crystal i nit iation fuse together. The fibre/ crystal attachment sites, known as basal caps, and the cones form the mammillary knobs layer which is :: 100- 110 llm thick. After the cones fuse with each other, continuing calcite deposition produces columnar crystals 10 -30 \u27m in diameter and :::200 llm in length. These crys tals form the palisade layer and are intermingled with a protein/polysaccharide matrix that differs in composition From the shell membranes. Over the columnar crystals is a thin layer (::S -8 \u27m thick), known as the vertical crystal layer, of small calcite crystals that are orientated perpendicular to the shell\u27s surface. The cuticle is the outermost layer of the shell; it is =10 mm thick and contains predominantly protein. Passing vertically through the palisade layer of the shell from valleys between the marrmillary knobs to the surface of the vertical crystal layer are funnel - shaped, unbranched pores, These pores are capped by the cuticle which is cracked and thus allows the diffusion of gases between the contents of the egg and its environment. The geometrical configuration of the cones in the mammillary knobs layer is related to the thickness of shell. Specific amino acids in the membrane fibres

    The Microstructure of the Hen\u27s Egg Shell - A Short Review

    Get PDF
    The structure of the hen\u27s egg shell can be divided into five separate layers . The Innermost layer consists of two distinct membranes known as the inner and outer shell membranes. These membranes are compos ed of networks of protein/polysaccharide fibres and are =70 mm thick. Attached to the outer fibres of the outer membrane are polycrystals of calcite (calcium carbonate) which extend outward in an inverse conical manner until the cones from several sites of crystal i nit iation fuse together. The fibre/ crystal attachment sites, known as basal caps, and the cones form the mammillary knobs layer which is :: 100- 110 llm thick. After the cones fuse with each other, continuing calcite deposition produces columnar crystals 10 -30 \u27m in diameter and :::200 llm in length. These crys tals form the palisade layer and are intermingled with a protein/polysaccharide matrix that differs in composition From the shell membranes. Over the columnar crystals is a thin layer (::S -8 \u27m thick), known as the vertical crystal layer, of small calcite crystals that are orientated perpendicular to the shell\u27s surface. The cuticle is the outermost layer of the shell; it is =10 mm thick and contains predominantly protein. Passing vertically through the palisade layer of the shell from valleys between the marrmillary knobs to the surface of the vertical crystal layer are funnel - shaped, unbranched pores, These pores are capped by the cuticle which is cracked and thus allows the diffusion of gases between the contents of the egg and its environment. The geometrical configuration of the cones in the mammillary knobs layer is related to the thickness of shell. Specific amino acids in the membrane fibres

    The effect of low-energy ion-implantation on the electrical transport properties of Si-SiO2 MOSFETs

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    Using silicon MOSFETs with thin (5nm) thermally grown SiO2 gate dielectrics, we characterize the density of electrically active traps at low-temperature after 16keV phosphorus ion-implantation through the oxide. We find that, after rapid thermal annealing at 1000oC for 5 seconds, each implanted P ion contributes an additional 0.08 plus/minus 0.03 electrically active traps, whilst no increase in the number of traps is seen for comparable silicon implants. This result shows that the additional traps are ionized P donors, and not damage due to the implantation process. We also find, using the room temperature threshold voltage shift, that the electrical activation of donors at an implant density of 2x10^12 cm^-2 is ~100%.Comment: 11 pages, 10 figure
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