Mesospheric observations with the EISCAT UHF radar during polar cap absorption events: <br>3. Comparison with simultaneous EISCAT VHF measurements

International audienceMesospheric observations were obtained by the EISCAT UHF and VHF radars during the solar proton event of March 1990. We present the first comparison of incoherent-scatter spectral measurements from the middle mesosphere using simultaneous, co-located observations by the two radars. VHF spectra observed with a vertical antenna were found to be significantly narrower than model predictions, in agreement with earlier UHF results. For antenna pointing directions that were significantly away from the vertical, the wider VHF radar beam gave rise to broadening of the observed spectra due to vertical shears in the horizontal wind. In this configuration, UHF spectral measurements were found to be more suitable for aeronomical applications. Both radar systems provide consistent and reliable estimates of the neutral wind. Spectral results using both the multipulse and pulse-to-pulse schemes were intercompared and their suitability for application to combined mesosphere ? lower thermosphere studies investigated

Acoustic field coherence in four-dimensionally variable shallow water environments : estimation using co-located horizontal and vertical line arrays

Underwater Acoustic Measurements (UAM) 2nd International Conference & Exhibition on "Underwater Acoustic Measurements: Technologies & Results," 25-29 June 2007, Heraklion, Crete, Greece.The implementation of two- and three-dimensional acoustic receiver arrays is challenging in the ocean environment. Fixed geometry and connectivity can only be built and maintained at great expense. However, such ideal arrays can be very powerful for signal detection, classification, and tracking, although many of the signal-processing methods employed are subject to constraints of acoustic field temporal and spatial coherence. Thus, understanding the processes at work determining coherence is essential because system effectiveness may then be predictable from environmental parameter input. To study acoustic fields and coherence over finite aperture, the research community has recently taken steps to enable routine use of co-located horizontal and vertical line arrays, typically arranged in the shape of the Roman letter L (or Greek ), with the horizontal leg on the seafloor. This is a small subset of all possible geometries, but it enables measurements of acoustic field coherence not possible with single line arrays. Here, new L-array measurements made in the SW06 field program are used to measure coherence and test coherence predictions via joint analysis of vertical and horizontal line array receptions. Impulsive mode arrivals (including mode multipath) from fixed sources will be estimated using the vertical array. Signals on the horizontal array, which is neither broadside nor endfire, will be compared with signals synthesized using the mode arrivals to estimate azimuthal decorrelation effects. Results can be compared with coherence estimates from computational and theoretical studies

Review of aquaculture and fish consumption in Bangladesh

Fish play a crucial role in the Bangladeshi diet, providing more than 60% of animal source food, representing a crucial source of micro-nutrients, and possessing an extremely strong cultural attachment. Fish (including shrimp and prawn) is the second most valuable agricultural crop, and its production contributes to the livelihoods and employment of millions. The culture and consumption of fish therefore has important implications for national food and nutrition security, poverty and growth. This review examines the current state of knowledge on the aquaculture sector and fish consumption in Bangladesh, based on extensive analysis of secondary sources (including unpublished data unavailable elsewhere), consultation with various experts and specially conducted surveys. The review is comprised of three sections. Section 1 describes the main systems of aquaculture production in terms of their technical and social characteristics and outputs. Section 2 addresses issues relating to seed and feed. The final section analyses fish consumption patterns and demand, and attempts to estimate the volumes of fish produced from a range of sources.Food fish, Aquaculture, Food consumption, Fish consumption, Pond culture, Rice field aquaculture, Bangladesh,

Elastic Pekeris waveguide normal mode solution comparisons against laboratory data

Following the derivation presented by Press and Ewing [Geophysics 15, 426-446 (1950)], a normal mode solution for the Pekeris waveguide problem with an elastic bottom is outlined. The analytic solution is benchmarked against data collected in an experiment performed at the Naval Research Laboratory [Collis et al., J. Acoust. Soc. Am. 122, 1987-1993 (2007)]. Comparisons reveal a close match between the analytic solution and experimental data. Results are strongly dependent on the accuracy of the horizontal wavenumbers for the modes, and horizontal wavenumber spectra are compared against those from the experimental data. (C) 2012 Acoustical Society of AmericaNational Science Foundation Division of Graduate Education [DGE-0638719

A Temporal Map in Geostationary Orbit: The Cover Etching on the EchoStar XVI Artifact

Geostationary satellites are unique among orbital spacecraft in that they experience no appreciable atmospheric drag. After concluding their respective missions, geostationary spacecraft remain in orbit virtually in perpetuity. As such, they represent some of human civilization's longest lasting artifacts. With this in mind, the EchoStar XVI satellite, to be launched in fall 2012, will play host to a time capsule intended as a message for the deep future. Inspired in part by the Pioneer Plaque and Voyager Golden Records, the EchoStar XVI Artifact is a pair of gold-plated aluminum jackets housing a small silicon disc containing one hundred photographs. The Cover Etching, the subject of this paper, is etched onto one of the two jackets. It is a temporal map consisting of a star chart, pulsar timings, and other information describing the epoch from which EchoStar XVI came. The pulsar sample consists of 13 rapidly rotating objects, 5 of which are especially stable, having spin periods < 10 ms and extremely small spindown rates. In this paper, we discuss our approach to the time map etched onto the cover and the scientific data shown on it; and we speculate on the uses that future scientists may have for its data. The other portions of the EchoStar XVI Artifact will be discussed elsewhere.Comment: Accepted for publication in Astronomical Journa

Observed limiting cases of horizontal field coherence and array performance in a time-varying internal wavefield

Author Posting. © Acoustical Society of America, 2008. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 124 (2008): EL97-EL103, doi:10.1121/1.2947630.Using a moored source and horizontal/vertical line array combination, horizontal coherence properties of high signal to noise ratio (>=20 dB) 100–1600 Hz signals have been measured. Internal waves in the area of the measurement created moving episodic sound-speed anomaly structures, influencing coherence length. Measured horizontal coherence scales for 100 Hz ranged from 5 to 20 acoustic wavelengths, and were inversely related to the sound-speed anomaly strength. Horizontal field properties were compared with fields computed using modal decompositions of the vertical signals. The comparison allows azimuthal field coherence properties to be studied apart from normal-mode interference effects.This work was funded by grants to Boston University and the Woods Hole Oceanographic Institution from the Ocean Acoustics Program at the U.S. Office of Naval Research, including an ONR Postdoctoral Fellowship award to the first author

Goal-oriented a posteriori error estimation for the travel time functional in porous media flows

In this article we consider the a posteriori error estimation and adaptive mesh refinement for the numerical approximation of the travel time functional arising in porous media flows. The key application of this work is in the safety assessment of radioactive waste facilities; in this setting, the travel time functional measures the time taken for a non-sorbing radioactive solute, transported by groundwater, to travel from a potential site deep underground to the biosphere. To ensure the computability of the travel time functional, we employ a mixed formulation of Darcy's law and conservation of mass, together with Raviart-Thomas H(div) conforming finite elements. The proposed a posteriori error bound is derived based on a variant of the standard Dual-Weighted-Residual approximation, which takes into account the lack of smoothness of the underlying functional of interest. The proposed adaptive refinement strategy is tested on both a simple academic test case and a problem based on the geological units found at the Sellafield site in the UK

The West Midlands Automotive Industry:The Road Downhill

This paper examines how the structure of the automotive industry in the West Midlands has changed since the 1970s. In the early 1970s the West Midlands accounted for circa 60 per cent of total car production in the UK. By 2008, this had dwindled to 18 per cent. The discussion here will focus particularly on the most likely reasons for the decline in volume production and the region’s increasing reliance on relatively small scale luxury car production. The automotive industry was caught up in the general de-industrialisation that took place in the region since the mid 1960s prior to the economic crisis of the early 1980s, as well as suffering from the effects of increasing globalization in the car industry itself. By 2008 the context for the sector had become the global financial crisis. Due to a lack of economies of scale and investment the domestic firms such as British Leyland and Rootes became increasingly unable to compete in the market place despite restructuring and government intervention. Similarly foreign direct investment by firms such as Chrysler, Peugeot, BMW and Ford through a series of takeovers failed to restore prosperity and eventually all of them withdrew from the region. The outcomes have led to factory closures and a hollowing out of both the assembly and component sides of the industry, leaving the region heavily dependent on Jaguar-Land Rover which has been acquired recently by the Indian conglomerate, Tata. This paper assesses the reasons for the decline of the automotive sector in the West Midlands region by contextualizing its growth and decline against that of the UK auto sector as a whole. Considerable emphasis is placed on the fates of a number of key firms in the region – the British Leyland Motor Corporation, MG Rover, Rootes and Jaguar – with explanations offered for their decline

Proline-Rich Peptides with Improved Antimicrobial Activity against E. coli, K. Pneumoniae, and A. Baumannii.

Proline-rich antimicrobial peptides (PrAMPs) are promising agents to combat multi-drug resistant pathogens due to a high antimicrobial activity, yet low cytotoxicity. A library of derivatives of the PrAMP Bac5(1-17) was synthesized and screened to identify which residues are relevant for its activity. In this way, we discovered that two central motifs -PIRXP- cannot be modified, while residues at N- and C- termini tolerated some variations. We found five Bac5(1-17) derivatives bearing 1-5 substitutions, with an increased number of arginine and/or tryptophan residues, exhibiting improved antimicrobial activity and broader spectrum of activity while retaining low cytotoxicity toward eukaryotic cells. Transcription/translation and bacterial membrane permeabilization assays showed that these new derivatives still retained the ability to strongly inhibit bacterial protein synthesis, but also acquired permeabilizing activity to different degrees. These new Bac5(1-17) derivatives therefore show a dual mode of action which could hinder the selection of bacterial resistance against these molecules

Reducing Poverty in California…Permanently

If California were to seriously commit to equalizing opportunity and reducing poverty, how might that commitment best be realized? This is of course a hypothetical question, as there is no evidence that California is poised to make such a serious commitment, nor have many other states gone much beyond the usual lip-service proclamations. There are many reasons for California’s complacency, but an important one is that most people think that poverty is intractable and that viable solutions to it simply don’t exist. When Californians know what needs to be done, they tend to go forward and get it done. When, for example, the state’s roads are in disrepair, there are rarely paralyzing debates about exactly how to go about fixing them; instead we proceed with the needed repairs as soon as the funds to do so are appropriated. The same type of sure and certain prescription might appear to be unavailable when it comes to reducing poverty. It is hard not to be overwhelmed by the cacophony of voices yielding a thick stream of narrow-gauge interventions, new evaluations, and piecemeal proposals.1 Although the research literature on poverty is indeed large and may seem confusing, recent advances have in fact been so fundamental that it is now possible to develop a science-based response to poverty. In the past, the causes of poverty were not well understood, and major interventions, such as the War on Poverty, had to be built more on hunch than science. It is an altogether different matter now. The causes of poverty are well established, and the effects of many possible policy responses to poverty are likewise well established. The simple purpose of this essay is to assemble these advances into a coherent plan that would, if implemented, reduce poverty in California substantially