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Practical Methods (practical + methods)
Selected AbstractsEnantiomer Separation: Fundamentals and Practical MethodsCHIRALITY, Issue 9 2006Hassan Y. Aboul-EneinArticle first published online: 5 JUL 200 No abstract is available for this article. [source] Infiltration and Inversion of Holographically Defined Polymer Photonic Crystal Templates by Atomic Layer Deposition,ADVANCED MATERIALS, Issue 12 2006S. King Practical methods of microfabrication are vital for the development of photonic-crystal-based signal processing. However, extension of the optical methods that dominate integrated circuit fabrication to three dimensions is challenging. This communication reports an essential step for creation of devices operating within a full photonic band gap: atomic layer deposition is used to create the high-index TiO2 replicas of holographically defined photonic crystals shown in the figure. [source] Practical methods for measuring the tortuosity of porous materials from binary or gray-tone tomographic reconstructionsAICHE JOURNAL, Issue 8 2009Cedric J. Gommes Abstract Two practical methods are proposed to measure the tortuosity of a porous or permeable material from its tomographic reconstruction. The first method is based on the direct measurement of the shortest distance between two points in the pores, and the second is based on the geodesic reconstruction of the pore or permeation space. Unlike the first method, the second can be directly applied to gray-tone tomograms, without the need of a segmentation step. The methods are illustrated with an electron tomogram of clay/plastic nanocomposite, an X-ray microtomogram of sandstone, and a series of model morphologies consisting of penetrable random spheres. For the latter series, the measured tortuosities compare very well with those derived independently from the theoretical effective diffusion coefficients. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Projecting 2D gene expression data into 3D and 4D spaceDEVELOPMENTAL DYNAMICS, Issue 4 2007Victor E. Gerth Abstract Video games typically generate virtual 3D objects by texture mapping an image onto a 3D polygonal frame. The feeling of movement is then achieved by mathematically simulating camera movement relative to the polygonal frame. We have built customized scripts that adapt video game authoring software to texture mapping images of gene expression data onto b-spline based embryo models. This approach, known as UV mapping, associates two-dimensional (U and V) coordinates within images to the three dimensions (X, Y, and Z) of a b-spline model. B-spline model frameworks were built either from confocal data or de novo extracted from 2D images, once again using video game authoring approaches. This system was then used to build 3D models of 182 genes expressed in developing Xenopus embryos and to implement these in a web-accessible database. Models can be viewed via simple Internet browsers and utilize openGL hardware acceleration via a Shockwave plugin. Not only does this database display static data in a dynamic and scalable manner, the UV mapping system also serves as a method to align different images to a common framework, an approach that may make high-throughput automated comparisons of gene expression patterns possible. Finally, video game systems also have elegant methods for handling movement, allowing biomechanical algorithms to drive the animation of models. With further development, these biomechanical techniques offer practical methods for generating virtual embryos that recapitulate morphogenesis. Developmental Dynamics 236:1036,1043, 2007. © 2007 Wiley-Liss, Inc. [source] Practical causal hysteretic dampingEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2007Naohiro Nakamura Abstract A number of experiments indicate that the internal damping corresponding to the energy dissipation of many materials is essentially frequency independent. Accordingly, an analysis model that can express such characteristics (called a hysteretic damping model) in the time domain is needed. Although a great number of investigations into this subject have been carried out, there are a few practical methods. In this paper, a simple hysteretic damping model which satisfies the causality condition is presented using an extension of the complex stiffness transfer method that the author has proposed. Compared with the energy proportional damping model and the Biot model, the applicability and the efficiency of this model to time history response analyses were confirmed well by example problems. Copyright © 2006 John Wiley & Sons, Ltd. [source] A practical method for estimating dynamic soil stiffness on surface of multi-layered soilEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2005Naohiro Nakamura Abstract It is important to estimate the influence of layered soil in soil,structure interaction analyses. Although a great number of investigations have been carried out on this subject, there are very few practical methods that do not require complex calculations. In this paper, a simple and practical method for estimating the horizontal dynamic stiffness of a rigid foundation on the surface of multi-layered soil is proposed. In this method, waves propagating in the soil are traced using the conception of the cone model, and the impulse response function can be calculated directly and easily in the time domain with a good degree of accuracy. The characteristics of the impedance, that is the transformed value to the frequency domain of the obtained impulse response, are studied using two- to four-layered soil models. The cause of the fluctuation of impedance is expressed clearly from its relation to reflected waves from the lower layer boundary in the model. Copyright © 2005 John Wiley & Sons, Ltd. [source] An epidemiological study of risk factors associated with the recurrence of equine grass sickness (dysautonomia) on previously affected premisesEQUINE VETERINARY JOURNAL, Issue 2 2004J. R. Newton Summary Reasons for performing study: The reasons why equine grass sickness (EGS) recurs on premises are unknown and, consequently, practical methods for reducing the risk of recurrence are not available. Objectives: To identify risk factors associated with recurrence of EGS on premises and to gain possible insights into the pathogenesis of the disease. Methods: Data on disease history and risk factors were collected by postal questionnaire from premises with EGS cases between 1st January 1997 and 31st December 2001. Data on variation in rates of recurrence of EGS for different risk factors were analysed using Poisson regression analysis. Results: Of 509 premises contacted, 305 (60%) returned useable questionnaires and 100 of these (33%) were classified as ,recurrent' premises. An overall median incidence rate for EGS of 2.1 EGS incidents/100 horses/premises/year was recorded. There was an increased rate of recurrence with higher numbers of horses, presence of younger animals, stud farms and livery/riding establishments, loam and sand soils, rearing of domestic birds and mechanical droppings removal. The rate of recurrence decreased with chalk soil, cograzing ruminants, grass cutting on pastures and removal of droppings by hand. Several statistically significant interactions were identified. Conclusions: Many of the findings are consistent with the theory that EGS is a toxico-infectious form of botulism. Several of the significant factors identified may directly or indirectly relate to soil disturbance and consequent soil contamination of grass, thereby increasing the rate of exposure of grazing horses to Clostridium botulinum, which resides in soil. Potential relevance: Identification of potentially modifiable risk factors may, ideally following validation in appropriately designed, controlled and randomised intervention studies, lead to practical measures to reduce the incidence of EGS on previously affected premises. [source] N -Allylideneamines Derived from Acrolein: Synthesis and Use as Acceptors of Two NucleophilesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2009Isao Mizota Abstract Two practical methods have been developed for the preparation of N -allylideneamines 1b,c. One involves the isomerization of propargylamines and the other the dehydration of acrolein. N -Allylideneamines 1b,c thus prepared were used as efficient substrates for 1,4- and 1,2-double nucleophilic addition reactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Application of multicriteria decision analysis in environmental decision makingINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 2 2005Gregory A. Kiker Abstract Decision making in environmental projects can be complex and seemingly intractable, principally because of the inherent trade-offs between sociopolitical, environmental, ecological, and economic factors. The selection of appropriate remedial and abatement strategies for contaminated sites, land use planning, and regulatory processes often involves multiple additional criteria such as the distribution of costs and benefits, environmental impacts for different populations, safety, ecological risk, or human values. Some of these criteria cannot be easily condensed into a monetary value, partly because environmental concerns often involve ethical and moral principles that may not be related to any economic use or value. Furthermore, even if it were possible to aggregate multiple criteria rankings into a common unit, this approach would not always be desirable because the ability to track conflicting stakeholder preferences may be lost in the process. Consequently, selecting from among many different alternatives often involves making trade-offs that fail to satisfy 1 or more stakeholder groups. Nevertheless, considerable research in the area of multicriteria decision analysis (MCDA) has made available practical methods for applying scientific decision theoretical approaches to complex multicriteria problems. This paper presents a review of the available literature and provides recommendations for applying MCDA techniques in environmental projects. A generalized framework for decision analysis is proposed to highlight the fundamental ingredients for more structured and tractable environmental decision making. [source] Managing treasury risks in the real worldJOURNAL OF CORPORATE ACCOUNTING & FINANCE, Issue 1 2005Karen Horcher Treasurers face many different kinds of risks. But it's one thing to read about them in a textbook and quite another to grapple with them in the real world. What are the various types of risks? How do these risks actually arise? And what practical methods can you use to assess exposure and risk? © 2005 Wiley Periodicals, Inc. [source] A practical method for 2D multiple-animal MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2007Marc S. Ramirez MS Abstract Purpose To investigate practical methods for achieving routine simultaneous 2D MRI of multiple animals in large-bore experimental scanners. Materials and Methods Three four-element array geometries were compared against a standard single-coil configuration in terms of image quality, ease of use, and data efficiency using a four-channel, 4.7 T small animal imaging system. Results A linear arrangement of volume resonators permits unobstructed animal preparation and use of an imaging protocol that is almost identical to the single-coil configuration without requiring any image correction or other additional postprocessing. Resulting in vivo images were visually indistinguishable from those acquired through the single-coil configuration. Conclusion The efficiency of animal studies employing 2D MRI techniques can be substantially improved by using a linear array of commercially available resonators. J. Magn. Reson. Imaging 2007;26:1162,1166. © 2007 Wiley-Liss, Inc. [source] Practical methods for measuring the tortuosity of porous materials from binary or gray-tone tomographic reconstructionsAICHE JOURNAL, Issue 8 2009Cedric J. Gommes Abstract Two practical methods are proposed to measure the tortuosity of a porous or permeable material from its tomographic reconstruction. The first method is based on the direct measurement of the shortest distance between two points in the pores, and the second is based on the geodesic reconstruction of the pore or permeation space. Unlike the first method, the second can be directly applied to gray-tone tomograms, without the need of a segmentation step. The methods are illustrated with an electron tomogram of clay/plastic nanocomposite, an X-ray microtomogram of sandstone, and a series of model morphologies consisting of penetrable random spheres. For the latter series, the measured tortuosities compare very well with those derived independently from the theoretical effective diffusion coefficients. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Carbon-based stock feed additives: a research methodology that explores ecologically delivered C biosequestration, alongside live weights, feed use efficiency, soil nutrient retention, and perennial fodder plantationsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2010Mark P McHenry Abstract There is considerable interest in reliable and practical methods to sequester carbon (C) into agricultural soils to both reduce atmospheric greenhouse gas concentrations and improve conventional productivity. This article outlines a research methodology to refine the efficacy and economics of using long-lived C species (biochars) as stock feed additives, produced from farm waste biomass, for ecologically delivered soil biosequestration, while generating renewable bioenergy. This article also draws attention to potential parallel outputs including annual feed use efficiency, fodder species expansion, soil nutrient retention, aquatic habitat protection, and forestry revegetation, using nitrogen-fixing perennial fodder plant species. A methodology to generate parallel results including standing fodder tree C sequestration, optimised production of Acacia spp. biochar, animal growth on high-tannin fodder with biochar feed additives, soil nutrient and stable C fractions, and economics of Acacia spp. bioenergy production. This form of research is contextually dependent on the regional agricultural production system, legislation, and surrounding ecosystem. Therefore, this article suggests the use of a scenario approach to include regionally specific levels of biochar integration with respect to the local prices for C, fossil fuels, meat and livestock, fertilisers, fodder, feed additives, water, renewable energy, revegetation and capital. Copyright © 2009 Society of Chemical Industry [source] Long-term effective population size of three endangered Colorado River fishesANIMAL CONSERVATION, Issue 2 2002Daniel Garrigan The extant genetic variation of a population is the legacy of both long-term and recent population dynamics. Most practical methods for estimating effective population size are only able to detect recent effects on genetic variation and do not account for long-term fluctuations in species abundance. The utility of a maximum likelihood estimator of long-term effective population size based upon the coalescent theory of gene genealogies is examined for three endangered Colorado River fishes: humpback chub (Gila cypha), bonytail chub (Gila elegans) and razorback sucker (Xyrauchen texanus). Extant mitochondrial DNA (mtDNA) variation in humpback chub suggests this species has retained its historical equilibrium genetic variation despite recent declines in abundance. The mtDNA variation in razorback suckers indicates the population was quite large and expanding prior to recent declines and that rare alleles still survive in the remnant populations. The remaining mtDNA variation in bonytail chub indicates that dramatic, recent declines may have already obliterated a substantial portion of any historical variation. The results from long-term effective population size analyses are consistent with known natural history and illustrate the utility of the analysis for endangered species management. [source] Cloning large natural product gene clusters from the environment: Piecing environmental DNA gene clusters back together with TARBIOPOLYMERS, Issue 9 2010Jeffrey H. Kim Abstract A single gram of soil can contain thousands of unique bacterial species, of which only a small fraction is regularly cultured in the laboratory. Although the fermentation of cultured microorganisms has provided access to numerous bioactive secondary metabolites, with these same methods it is not possible to characterize the natural products encoded by the uncultured majority. The heterologous expression of biosynthetic gene clusters cloned from DNA extracted directly from environmental samples (eDNA) has the potential to provide access to the chemical diversity encoded in the genomes of uncultured bacteria. One of the challenges facing this approach has been that many natural product biosynthetic gene clusters are too large to be readily captured on a single fragment of cloned eDNA. The reassembly of large eDNA-derived natural product gene clusters from collections of smaller overlapping clones represents one potential solution to this problem. Unfortunately, traditional methods for the assembly of large DNA sequences from multiple overlapping clones can be technically challenging. Here we present a general experimental framework that permits the recovery of large natural product biosynthetic gene clusters on overlapping soil-derived eDNA cosmid clones and the reassembly of these large gene clusters using transformation-associated recombination (TAR) in Saccharomyces cerevisiae. The development of practical methods for the rapid assembly of biosynthetic gene clusters from collections of overlapping eDNA clones is an important step toward being able to functionally study larger natural product gene clusters from uncultured bacteria. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 833,844, 2010. [source] Heterologous GPCR Expression: A Bottleneck to Obtaining Crystal StructuresBIOTECHNOLOGY PROGRESS, Issue 3 2007Emily C. McCusker G protein-coupled receptors (GPCRs) are an important, medically relevant class of integral membrane proteins. Laboratories throughout all disciplines of science devote time and energy into developing practical methods for the discovery, isolation, and characterization of these proteins. Since the crystal structure of rhodopsin was solved 6 years ago, the race to determine high-resolution structures of more GPCRs has gained momentum. Since certain GPCRs are currently produced at sufficient levels for X-ray crystallography trials, it is speculated that heterologous expression of GPCRs may no longer be a bottleneck in obtaining crystal structures. This Review focuses on the current approaches in heterologous expression of GPCRs and explores the problems associated with obtaining crystal structures from GPCRs expressed in different systems. Although milligram amounts of certain GPCRs are attainable, the majority of GPCRs are still either produced at very low levels or not at all. Developing reliable expression techniques for GPCRs is still a major priority for the structural characterization of GPCRs. [source] Small business responsibility in developing countries: a threat or an opportunity?BUSINESS STRATEGY AND THE ENVIRONMENT, Issue 1 2005Ralph Luken Many developing country small and medium sized enterprises (SMEs) that are exporters see themselves facing a dilemma. They do not know how to respond to the rising social and environmental requirements of global buyers and supply chains and fear that were they to do so they would lose their competitive edge. However, they are aware that if they do not meet these requirements, they will not be able to access new foreign markets and may lose the contracts they already have. To investigate whether practical methods exist for resolving this dilemma, the United Nations Industrial Development Organization (UNIDO) carried out a one year project with 22 SMEs in four Asian countries. The results suggest that well targeted, enterprise-specific efforts to meet corporate social responsibility (CSR) requirements can make a positive contribution to both short-term profitability and longer-term competitiveness. The ,business case' for CSR appears strongest in the environmental area, but measures in that area can act as a ,starter motor' for tackling more systemic ,social' problems. Furthermore, tackling social issues at the workplace can feed back positively to improve the sustainability of the environmental improvement measures. Copyright © 2005 John Wiley & Sons, Ltd and ERP Environment. [source] Hydrogen in Porous Tetrahydrofuran Clathrate HydrateCHEMPHYSCHEM, Issue 9 2008Fokko M. Mulder Dr. Abstract The lack of practical methods for hydrogen storage is still a major bottleneck in the realization of an energy economy based on hydrogen as energy carrier.1 Storage within solid-state clathrate hydrates,2,4 and in the clathrate hydrate of tetrahydrofuran (THF), has been recently reported.5,,6 In the latter case, stabilization by THF is claimed to reduce the operation pressure by several orders of magnitude close to room temperature. Here, we apply in situ neutron diffraction to show that,in contrast to previous reports[5,,6],hydrogen (deuterium) occupies the small cages of the clathrate hydrate only to 30,% (at 274 K and 90.5 bar). Such a D2 load is equivalent to 0.27 wt.,% of stored H2. In addition, we show that a surplus of D2O results in the formation of additional D2O ice Ih instead of in the production of sub-stoichiometric clathrate that is stabilized by loaded hydrogen (as was reported in ref. 6). Structure-refinement studies show that [D8]THF is dynamically disordered, while it fills each of the large cages of [D8]THF,17D2O stoichiometrically. Our results show that the clathrate hydrate takes up hydrogen rapidly at pressures between 60 and 90 bar (at about 270 K). At temperatures above ,220 K, the H-storage characteristics of the clathrate hydrate have similarities with those of surface-adsorption materials, such as nanoporous zeolites and metal,organic frameworks,7,,8 but at lower temperatures, the adsorption rates slow down because of reduced D2 diffusion between the small cages. [source] Comparison of practical methods for urinary glycosaminoglycans and serum hyaluronan with clinical activity scores in patients with Graves' ophthalmopathyCLINICAL ENDOCRINOLOGY, Issue 6 2004João R. M. Martins Summary objective, Immunosuppressive treatment of Graves' opthalmopathy (GO) should be restricted to patients with active eye disease, but assessing disease activity is difficult. Several methods to evaluate GO activity have been introduced, but none of them is satisfactory. Glycosaminoglycans (GAGs) are complex polysaccharides that participate on the pathogenesis of GO and attempts to correlate its local increase to urinary GAGs (uGAGs) or serum hyaluronan (sHA) have been made, but the available techniques are labourious, time-consuming and difficult for routine use. The aim of the present study is to develop practical and simple methods for uGAGs and sHA and compare them to the activity and severity of thyroid-associated ophthalmopathy. design, patients and measurements, We developed a microelectrophoresis technique for uGAGs and a fluoroassay for sHA and assessed each in 152 patients with Graves' disease, 25 without GO and 127 with GO, classified according to the Clinical Activity Score (CAS). All patients had been euthyroid for > 2 months. results, Patients with inactive disease (CAS = 2, n = 100) had uGAGs (4·2 ± 1·3 µg/mg/creatinine) and sHA (11·1 ± 7·2 µg/l) that did not differ from normal subjects (3·1 ± 1·1 µg/mg/creatinine, n = 138 and 13·9 ± 9·6 µg/l, n = 395). In contrast, patients with active eye disease (CAS = 3, n = 27) had uGAGs (8·4 ± 2·7 µg/mg/creatinine) and sHA (32·3 ± 17·8 µg/l) 2,3 times higher than those patients with inactive eye disease. Using a cut-off of 6·1 µg/mg creatinine for uGAGs and 20·7 µg/l for sHA we found, respectively, 85% and 81% sensitivity and 93% and 91% specificity for each test. The positive and negative predictive values were 77% and 96% for uGAGs and 71% and 95% for sHA. conclusion, Employing these two new methods we have established a significant relationship between the levels of uGAGs and/or sHA and the clinical activity of GO. Therefore, together with CAS, uGAGs determination, and, to a lesser degree, sHA, would be very useful in the discrimination from active and inactive ocular disease and aid in deciding on the best therapy for GO patients. [source] | |||||||||||||||||||