2,617 research outputs found

    How Engineers can Take Advantage of Their Skills to Slow the Impacts of Climate Change

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    Our planet is suffering from climate change which is affecting all living creatures on Earth and is beginning to have negative impacts on our lives. Some sources that are contributing to this climate change, or global warming, include greenhouse gas emissions from cars and factories, methane released from landfills, and deforestation, just to name a few. If you were to investigate each of these sources, you would find that there are engineers involved in some or many aspects of the processes for each. Engineers need to be held responsible and take advantage of their skills to extend the life of the planet. This research paper explains the ways in which engineers can use their skills to develop new technologies that will reduce the impacts of climate change, lower the amount of greenhouse gas and methane released, and improve the overall health of the planet

    Sound pressure levels within the ear canal of iPod users

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    Portable listening devices, specifically iPods are becoming more and more popular among teens and young adults. According to Apple\u27s quarterly financial results in March 2008, total iPod sales reached close to 152,000,000 since their release in January 2001 (Apple, 2008). Because nearly 15 million individuals suffer from noise induced hearing loss, listening levels of individuals using iPods are of main concern to audiologists. The purpose of this dissertation is to determine (1) average listening levels of males and females, as well as experienced and inexperienced iPod users and (2) if a certain groups of individuals are at more of a risk for hearing loss. Forty listeners with normal hearing (20 males and 20 females aged 18-25) were asked to set an iPod to their preferred listening level for a predetermined song (called the music stimulus). Then, 8 probe microphone measurements were obtained in a sound treated booth for the music stimulus and a white noise stimulus. Specifically. 4 measurements were obtained for each stimulus (music and noise) to determine the sound pressure levels produced in individuals\u27 ear canal. The results indicated that when listeners set their iPods to their preferred listening levels, sound pressure levels of males and females were similar. Additionally, experienced and inexperienced iPod users listened at similar levels. Furthermore, 7 of the 40 participants listened at levels that could be harmful to their hearing

    Survey of the plasma electron environment of Jupiter: A view from Voyager

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    The plasma environment within Jupiter's bow shock is considered in terms of the in situ, calibrated electron plasma measurements made between 10 eV and 5.95 keV by the Voyager plasma science experiment (PLS). Measurements were analyzed and corrected for spacecraft potential variations; the data were reduced to nearly model independent macroscopic parameters of the local electron density and temperature. It is tentatively concluded that the radial temperature profile within the plasma sheet is caused by the intermixing of two different electron populations that probably have different temporal histories and spatial paths to their local observation. The cool plasma source of the plasma sheet and spikes is probably the Io plasma torus and arrives in the plasma sheet as a result of flux tube interchange motions or other generalized transport which can be accomplished without diverting the plasma from the centrifugal equator. The hot suprathermal populations in the plasma sheet have most recently come from the sparse, hot mid-latitude "bath" of electrons which were directly observed juxtaposed to the plasma sheet

    Zeeman Slowers for Strontium based on Permanent Magnets

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    We present the design, construction, and characterisation of longitudinal- and transverse-field Zeeman slowers, based on arrays of permanent magnets, for slowing thermal beams of atomic Sr. The slowers are optimised for operation with deceleration related to the local laser intensity (by the parameter ϵ\epsilon), which uses more effectively the available laser power, in contrast to the usual constant deceleration mode. Slowing efficiencies of up to ≈\approx 1818 % are realised and compared to those predicted by modelling. We highlight the transverse-field slower, which is compact, highly tunable, light-weight, and requires no electrical power, as a simple solution to slowing Sr, well-suited to spaceborne application. For 88^{88}Sr we achieve a slow-atom flux of around 6×1096\times 10^9 atoms \,s−1^{-1} at 3030 ms−1^{-1}, loading approximately 5×1085\times 10^8 atoms in to a magneto-optical-trap (MOT), and capture all isotopes in approximate relative natural abundances

    The Herschel Lensing Survey (HLS): Overview

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    The Herschel Lensing Survey (HLS) will conduct deep PACS and SPIRE imaging of ∼40 massive clusters of galaxies. The strong gravitational lensing power of these clusters will enable us to penetrate through the confusion noise, which sets the ultimate limit on our ability to probe the Universe with Herschel. Here we present an overview of our survey and a summary of the major results from our science demonstration phase (SDP) observations of the Bullet cluster (z = 0.297). The SDP data are rich and allow us to study not only the background high-redshift galaxies (e.g., strongly lensed and distorted galaxies at z = 2.8 and 3.2) but also the properties of cluster-member galaxies. Our preliminary analysis shows a great diversity of far-infrared/submillimeter spectral energy distributions (SEDs), indicating that we have much to learn with Herschel about the properties of galaxy SEDs. We have also detected the Sunyaev-Zel’dovich (SZ) effect increment with the SPIRE data. The success of this SDP program demonstrates the great potential of the Herschel Lensing Survey to produce exciting results in a variety of science areas

    Tests of Profiled Steel Decks with V-stiffeners

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    The size and position of intermediate stiffeners in the compression flanges of thin-walled profiled steel decks exerts a strong influence on the dominant buckling mode of the flange. The ability of the deck to provide both high load carrying capacity before the onset of elastic buckling and a high ultimate load capacity may therefore be affected. A programme of tests to determine the effectiveness of intermediate stiffeners in controlling buckling modes has been undertaken. A series of specimens were loaded in pure bending resulting in various buckling waveforms prior to ultimate failure through a plastic collapse mechanism. All specimens were brake-pressed to designs that were chosen to ensure that the primary buckling took place in the elastic range and was not affected by plasticity. The experimentally determined buckling stresses were found to be comparable with studies performed using a computer analysis based on the finite strip method in which both local and distortional buckling modes were predicted. The test rig developed for the programme successfully approximated the boundary conditions implicit in the numerical model and prevented premature failure due to localised stressing at the specimen ends. A simplified design procedure for distortional buckling is proposed. The existing design procedure for local buckling in the Australian Standard AS1538-1988 is confirmed

    Modelling and simulation of biased agonism dynamics at a G protein-coupled receptor.

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    Theoretical models of G protein-coupled receptor (GPCR) concentration-response relationships often assume an agonist producing a single functional response via a single active state of the receptor. These models have largely been analysed assuming steady-state conditions. There is now much experimental evidence to suggest that many GPCRs can exist in multiple receptor conformations and elicit numerous functional responses, with ligands having the potential to activate different signalling pathways to varying extents-a concept referred to as biased agonism, functional selectivity or pluri-dimensional efficacy. Moreover, recent experimental results indicate a clear possibility for time-dependent bias, whereby an agonist's bias with respect to different pathways may vary dynamically. Efforts towards understanding the implications of temporal bias by characterising and quantifying ligand effects on multiple pathways will clearly be aided by extending current equilibrium binding and biased activation models to include G protein activation dynamics. Here, we present a new model of time-dependent biased agonism, based on ordinary differential equations for multiple cubic ternary complex activation models with G protein cycle dynamics. This model allows simulation and analysis of multi-pathway activation bias dynamics at a single receptor for the first time, at the level of active G protein (αGTP), towards the analysis of dynamic functional responses. The model is generally applicable to systems with NG G proteins and N* active receptor states. Numerical simulations for NG=N*=2 reveal new insights into the effects of system parameters (including cooperativities, and ligand and receptor concentrations) on bias dynamics, highlighting new phenomena including the dynamic inter-conversion of bias direction. Further, we fit this model to 'wet' experimental data for two competing G proteins (Gi and Gs) that become activated upon stimulation of the adenosine A1 receptor with adenosine derivative compounds. Finally, we show that our model can qualitatively describe the temporal dynamics of this competing G protein activation

    The petrology and petrography of the igneous rocks of Riley County, Kansas

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    Call number: LD2668 .T4 1953 B7Master of Scienc

    Interaction of the solar wind with Venus

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    Two topics related to the interaction of the solar wind with Venus are considered. First, a short review of the experimental evidence with particular attention to plasma measurements carried out on Mariner-5 and Mariner-10 is given. Secondly, the results of some recent theoretical work on the interaction of the solar wind with the ionosphere of Venus are summarized
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