7,425 research outputs found
Pneumatic shutoff and time-delay valve operates at controlled rate
Shutoff and time delay valve, which incorporates a metering spool that moves at constant velocity under pneumatic pressure and spring compression, increases fluid-flow area at a uniform rate. Diaphragm areas, control cavity volume, and bleed-orifice size may be varied to give any desired combination of time delay and spool travel time
Including the urban heat island in spatial heat health risk assessment strategies: a case study for Birmingham, UK
Background
Heatwaves present a significant health risk and the hazard is likely to escalate with the increased future temperatures presently predicted by climate change models. The impact of heatwaves is often felt strongest in towns and cities where populations are concentrated and where the climate is often unintentionally modified to produce an urban heat island effect; where urban areas can be significantly warmer than surrounding rural areas. The purpose of this interdisciplinary study is to integrate remotely sensed urban heat island data alongside commercial social segmentation data via a spatial risk assessment methodology in order to highlight potential heat health risk areas and build the foundations for a climate change risk assessment. This paper uses the city of Birmingham, UK as a case study area.
Results
When looking at vulnerable sections of the population, the analysis identifies a concentration of "very high" risk areas within the city centre, and a number of pockets of "high risk" areas scattered throughout the conurbation. Further analysis looks at household level data which yields a complicated picture with a considerable range of vulnerabilities at a neighbourhood scale.
Conclusions
The results illustrate that a concentration of "very high" risk people live within the urban heat island, and this should be taken into account by urban planners and city centre environmental managers when considering climate change adaptation strategies or heatwave alert schemes. The methodology has been designed to be transparent and to make use of powerful and readily available datasets so that it can be easily replicated in other urban areas
Velocity weakening and possibility of aftershocks in nanofriction experiments
We study the frictional behavior of small contacts as those realized in the
atomic force microscope and other experimental setups, in the framework of
generalized Prandtl-Tomlinson models. Particular attention is paid to
mechanisms that generate velocity weakening, namely a decreasing average
friction force with the relative sliding velocity.The mechanisms studied model
the possibility of viscous relaxation, or aging effects in the contact. It is
found that, in addition to producing velocity weakening, these mechanisms can
also produce aftershocks at sufficiently low sliding velocities. This provides
a remarkable analogy at the microscale, of friction properties at the
macroscale, where aftershocks and velocity weakening are two fundamental
features of seismic phenomena.Comment: 8 pages, 7 figure
The Stokes-Einstein Relation in Supercooled Aqueous Solutions of Glycerol
The diffusion of glycerol molecules decreases with decreasing temperature as
its viscosity increases in a manner simply described by the Stokes-Einstein(SE)
relation. Approaching the glass transition, this relation breaks down as it
does with a number of other pure liquid glass formers. We have measured the
diffusion coefficient for binary mixtures of glycerol and water and find that
the Stokes-Einstein relation is restored with increasing water concentration.
Our comparison with theory suggests that addition of water postpones the
formation of frustration domainsComment: 4 Pages and 3 Figure
Phage display selected magnetite interacting Adhirons for shape controlled nanoparticle synthesis
Adhirons are robust, well expressing, peptide display scaffold proteins, developed as an effective alternative
to traditional antibody binding proteins for highly specific molecular recognition applications. This paper
reports for the first time the use of these versatile proteins for material binding, and as tools for
controlling material synthesis on the nanoscale. A phage library of Adhirons, each displaying two variable
binding loops, was screened to identify specific proteins able to interact with [100] faces of cubic
magnetite nanoparticles. The selected variable regions display a strong preference for basic residues
such as lysine. Molecular dynamics simulations of amino acid adsorption onto a [100] magnetite surface
provides a rationale for these interactions, with the lowest adsorption energy observed with lysine. These
proteins direct the shape of the forming nanoparticles towards a cubic morphology in room temperature
magnetite precipitation reactions, in stark contrast to the high temperature, harsh reaction conditions
currently used to produce cubic nanoparticles. These effects demonstrate the utility of the selected
Adhirons as novel magnetite mineralization control agents using ambient aqueous conditions. The
approach we outline with artificial protein scaffolds has the potential to develop into a toolkit of novel
additives for wider nanomaterial fabrication
The Rest of the Story: Print News Components in Agricultural Communications Programs at Land·Grant Universities
The purpose of this study was to learn about print news units within agricultural communications departments across the land-grant university system
Community-Based Grazing Marketing: Barriers and Benefits Related to the Adoption of Best Management Practices in Grazing Systems
Environmental impacts of less than optimal grazing management choices can be intense and widespread. Improved communication of responsible grazing practices known as best management practices (BMPs) may increase adoption of these practices and increase sustainability of grazing systems. Community-based social marketing (CBSM) is a tool that can be used by communicators to generate behavior changes. This strategy emphasizes the identification of barriers to goal behaviors and the development of strategies to overcome them. This study sought to identify barriers and benefits associated with the adoption of grazing BMPs. Barriers identified include water availability and quality, and leasing and renting land. Benefits identified were increased resiliency through rotational grazing, improved watering and burning practices
Contact and Friction of Nano-Asperities: Effects of Adsorbed Monolayers
Molecular dynamics simulations are used to study contact between a rigid,
nonadhesive, spherical tip with radius of order 30nm and a flat elastic
substrate covered with a fluid monolayer of adsorbed chain molecules. Previous
studies of bare surfaces showed that the atomic scale deviations from a sphere
that are present on any tip constructed from discrete atoms lead to significant
deviations from continuum theory and dramatic variability in friction forces.
Introducing an adsorbed monolayer leads to larger deviations from continuum
theory, but decreases the variations between tips with different atomic
structure. Although the film is fluid, it remains in the contact and behaves
qualitatively like a thin elastic coating except for certain tips at high
loads. Measures of the contact area based on the moments or outer limits of the
pressure distribution and on counting contacting atoms are compared. The number
of tip atoms making contact in a time interval grows as a power of the interval
when the film is present and logarithmically with the interval for bare
surfaces. Friction is measured by displacing the tip at a constant velocity or
pulling the tip with a spring. Both static and kinetic friction rise linearly
with load at small loads. Transitions in the state of the film lead to
nonlinear behavior at large loads. The friction is less clearly correlated with
contact area than load.Comment: RevTex4, 17 pages, 13 figure
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