27,185 research outputs found
Development of hazard analysis and critical control points (HACCP) procedures to control organic chemical hazards in the agricultural production of raw food commodities
Hazard Analysis by Critical Control Points (HACCP) is a systematic approach to the identification, assessment and control of hazards in the food chain. Effective HACCP requires the consideration of all possible hazards, i.e., chemical, microbiological and physical. However, current procedures focus primarily upon microbiological and physical hazards, and, to date, chemical aspects of HACCP have received relatively little attention. Consequently, this report discusses the application of HACCP to organic chemical contaminants and the particular problems that are likely to encounter within the agricultural sector. It also presents generic templates for the development of organic chemical contaminant HACCP procedures for selected raw food commodities, i.e., cereal crops, raw meats and milk
Synthesis and characterisation of Fe<sub>6</sub> and Fe<sub>12</sub> clusters using bicine
Reaction of bicine {BicH3, N,N-bis(2-hydroxyethyl)glycine} with an Fe(III) oxo-centered pivalate triangle in MeCN in the presence of Et<sub>2</sub>NH yields [Et<sub>2</sub>NH<sub>2</sub>]<sub>2</sub>[Fe<sub>6</sub>O<sub>2</sub>(OH)<sub>2</sub>(Bic)<sub>2</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>8</sub>], which possesses an S = 5 ground state.
Changing the base to NaOMe produces [Fe<sub>12</sub>O<sub>4</sub>(Bic)<sub>4</sub>(HBic)<sub>4</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>8</sub>], which contains two Fe6 units bridged by the carboxylate arms from the bicine ligands. The complex displays strong antiferromagnetic coupling leading to an S = 0 ground state
Biological implications of a discrete mathematical model for collagen deposition and alignment in dermal wound repair
We deveiop a novel mathematical model for collagen deposition and alignment during dermal wound healing. We focus on the interactions between fibroblasts, modelled as discrete entities, and a continuous extracellular matrix composed of collagen and a fibrin based blood clot. There are four basic interactions assumed in the model: fibroblasts orient the collagen matrix, fibroblasts produce and degrade collagen and fibrin and the matrix directs the fibroblasts and determines the speed of the cells. Several factors which influence the alignment of collagen are examined and related to current anti-scarring therapies using transforming growth factor ß. The most influential of these factors are cell speed and, more importantly for wound healing, the influx of fibroblasts from surrounding tissue
Secondary Structures in Long Compact Polymers
Compact polymers are self-avoiding random walks which visit every site on a
lattice. This polymer model is used widely for studying statistical problems
inspired by protein folding. One difficulty with using compact polymers to
perform numerical calculations is generating a sufficiently large number of
randomly sampled configurations. We present a Monte-Carlo algorithm which
uniformly samples compact polymer configurations in an efficient manner
allowing investigations of chains much longer than previously studied. Chain
configurations generated by the algorithm are used to compute statistics of
secondary structures in compact polymers. We determine the fraction of monomers
participating in secondary structures, and show that it is self averaging in
the long chain limit and strictly less than one. Comparison with results for
lattice models of open polymer chains shows that compact chains are
significantly more likely to form secondary structure.Comment: 14 pages, 14 figure
Enhanced LANDSAT images of Antarctica and planetary exploration
Since early in the LANDSAT program, black-and-white paper prints of band 7 (near infrared) of the LANDSAT multispectral scanner have been used extensively to prepare semicontrolled maps of Antarctica. Image-processing techniques are now employed to enhance fine detail and to make controlled image-mosaic maps in color. LANDSAT multispectral images of Antarctica help to expand our knowledge of extraterrestrial bodies by showing bare-ice areas as bright blue patches; on such patches meteorites tend to be concentrated and are collected. Many subtle flow features in Antarctic ice streams resemble features at the mouths of Martian outflow channels, which suggests that the channels also contained ice. Furthermore, flow lines in Antarctic ice sheets that merge with ice shelves resemble Martian flow features associated with dissected terrain along the Martian northern highland margin, and support the concept that ice was involved in the transport of material from the southern highlands to the northern lowland plains. In Antarctica, as on Mars, the virtual absence of fluvial activity over millions of years has permitted the growth of glacial and eolian features to unusually large sizes
Developing collaborative partnerships with culturally and linguistically diverse families during the IEP process
Family participation in the special education process has been federally mandated for 40 years, and educators recognize that effective collaboration with their students’ families leads to improved academic and social outcomes for students. However, while some family-school relationships are positive and collaborative, many are not, particularly for culturally and linguistically diverse (CLD) families. This article provides practice guidelines based in research for teachers who seek to improve their practices when working with CLD families who have children served by special education
Quiz Cube:an AR mobile learning application
The current paper presents the Quiz Cube application and its evaluation. The Quiz Cube application is an AR mobile learning application for students and teachers to easily make and use AR UI system using fiducial marker cubes. AR as a platform is just now reaching its full potential. Since smartphones and mobile devices are now at a sufficiently large user base, it is worth looking at the potential for an extremely small form factor delivery system that is flexible, easily modified, and used by educators and students. An easily modifiable AR learning experience will present an AR Mobile platform development, interactive museums, and the chosen subject in a new style. This method can be shown to improve not only knowledge of the chosen subject through investigation, but a better understanding of development potentials for the mobile devices now ubiquitous to students. The Quiz Cube application was evaluated in three different ways and the results are presented here
Share Purchase Plans in Australia: Issuer Characteristics and Valuation Implications
Share purchase plans (SPPs) are offered exclusively to a company's registered shareholders, who may purchase up to $5,000 worth of shares in a 12-month period at a discount to the market price and without any brokerage charge. They have become one of the most frequently used mechanisms for raising publicly traded equity capital in Australia, yet little is known about them from a financial markets perspective. We address this deficiency by documenting the characteristics of Australian firms that have adopted SPPs and assessing their short-term and long-term valuation implications. We find that SPPs are more likely to be issued by firms with lower levels of liquidity and relatively large numbers of shareholders. They have a negative announcement effect, which is associated with the size of the issue, the prior share-price runup, the issue-price discount, the firm's industry, and whether there is enough time for non-shareholders to buy shares in order to participate. Long-run underperformance is also found over extended periods, consistent with much of the seasoned equity offering (SEO) literature. The SPP-issuer did not perform as badly if it was in the mining industry, if it was audited by a ‘Big-N’ firm, or if the issue was underwritten. Conversely, the greater the issue discount, the worse the issuer's long-run performance. © 2008, SAGE Publications. All rights reserved
Laser Velocimeter Measurements in the Leakage Annulus of a Whirling Shrouded Centrifugal Pump
Previous experiments conducted in the Rotor Force Test Facility at the California Institute of Technology have thoroughly examined the effect of leakage flows on the rotordynamic forces on a centrifugal pump impeller undergoing a prescribed circular whirl. These leakage flows have been shown to contribute substantially to the total fluid induced forces acting on a pump. However, to date nothing is known of the flow field in the leakage annulus of shrouded centrifugal pumps. No attempt has been made to qualitatively or quantitatively examine the velocity field in the leakage annulus. Hence the test objective of this experiment is to acquire fluid velocity data for a geometry representative of the leakage annulus of a shrouded centrifugal pump while the rotor is whirling using laser velocimetry. Tests are performed over a range of whirl ratios and a flowrate typical of Space Shuttle Turbopump designs. In addition to a qualitive study of the flow field, the velocity data can be used to anchor flow models
Spin-dependent phenomena and device concepts explored in (Ga,Mn)As
Over the past two decades, the research of (Ga,Mn)As has led to a deeper
understanding of relativistic spin-dependent phenomena in magnetic systems. It
has also led to discoveries of new effects and demonstrations of unprecedented
functionalities of experimental spintronic devices with general applicability
to a wide range of materials. In this article we review the basic material
properties that make (Ga,Mn)As a favorable test-bed system for spintronics
research and discuss contributions of (Ga,Mn)As studies in the general context
of the spin-dependent phenomena and device concepts. Special focus is on the
spin-orbit coupling induced effects and the reviewed topics include the
interaction of spin with electrical current, light, and heat.Comment: 47 pages, 41 figure
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