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Careful Choice (careful + choice)
Selected AbstractsElectrokinetic supercharging for highly efficient peptide preconcentration in capillary zone electrophoresisELECTROPHORESIS, Issue 7 2008Jean-Marc Busnel Abstract Electrokinetic supercharging has been integrated in CZE for the development of a highly sensitive methodology for protein tryptic digest analysis. A careful choice of the experimental conditions led to sensitivity enhancement factors between 1000 and 10,000 whilst maintaining a satisfactory resolution. Peptides in the low nanomolar concentration range have been detected despite the use of the poorly sensitive UV absorbance detection mode. The buffer system used in this study is fully suitable for coupling CE to MS. [source] Immobilization: Reversible Immobilization onto PEG-based Emulsion-templated Porous Polymers by Co-assembly of Stimuli Responsive Polymers (Adv. Mater.ADVANCED MATERIALS, Issue 1 20091/2009) Reversible immobilization onto the surface of highly porous polymers through co-assembly of stimuli-responsive polymers is reported on p. 55 by Neil Cameron and co-workers. Elastin-based side-chain polymers (EBPs) are prepared by RAFT polymerization and attached to the surface of PEG-based emulsion-templated porous polymers. By careful choice of EBP molecular weight and experimental conditions, pH-controlled reversible co-assembly of a complementary EBP from solution is demonstrated. [source] Reducing subjectivity in the assessment of the job environment: development of the Factual Autonomy Scale (FAS)JOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 4 2003Paul E. Spector Self-report measures of job stressors have been criticized for being too subjective, rendering relations with other variables inconclusive. The Factual Autonomy Scale (FAS) was developed to reduce subjectivity by careful choice of fact-based items. Results of two studies showed that when compared to the Job Diagnostic Survey autonomy scale, the FAS demonstrated superior convergent validity with alternate sources (supervisors in Study 1 and coworkers in Study 2), and discriminant validity when correlated with the remaining JDS core characteristics subscales. In addition, the FAS was correlated to a lesser extent than the JDS autonomy scale with job satisfaction. Incumbent FAS scores and not JDS scores correlated significantly with job performance as assessed by supervisors. It is suggested that it is feasible to develop fact-based items for scales of the work environment that reduce the degree of subjectivity of responses. Copyright © 2003 John Wiley & Sons, Ltd. [source] Effect of the challenger experience on elementary children's attitudes to scienceJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 10 2002Tina Jarvis This research explored how the Challenger experience influenced over 655 elementary boys' and girls' general attitudes to science and space during the 5 months after their visit by examining their responses to four different attitude scales. These were administered to the 10- to 11-year-olds immediately before and after the Challenger experience as well as 2 and 5 months later. Knowledge tests were also administered before and after the visit. A sample of children completed an existing measure of anxiety. Although there were mainly positive outcomes immediately after the Challenger experience, there were some negative effects. There were also noticeable differences between boys and girls. Some 24% of pupils were inspired to become scientists. There was also less fear of space travel with a greater appreciation of the use of science to protect the planet after the visit. Most girls improved and maintained their attitudes toward science in society. A sizeable number of pupils were relatively unaffected by the experience and there was a significant negative effect on a small group of anxious girls. There are indications that previsit preparation and careful choice of roles during the simulation are important. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 979,1000, 2002 [source] An introduction to coil array design for parallel MRINMR IN BIOMEDICINE, Issue 3 2006Michael A. Ohliger Abstract The basic principles of radiofrequency coil array design for parallel MRI are described from both theoretical and practical perspectives. Because parallel MRI techniques rely on coil array sensitivities to provide spatial information about the sample, a careful choice of array design is essential. The concepts of coil array spatial encoding are first discussed from four qualitative perspectives. These qualitative descriptions include using coil arrays to emulate spatial harmonics, choosing coils with selective sensitivities to aliased pixels, using coil sensitivities with broad k -space reception profiles, and relying on detector coils to provide a set of generalized projections of the sample. This qualitative discussion is followed by a quantitative analysis of coil arrays, which is discussed in terms of the baseline SNR of the received images as well as the noise amplifications (g -factor) in the reconstructed data. The complications encountered during the experimental evaluation of coil array SNR are discussed, and solutions are proposed. A series of specific array designs are reviewed, with an emphasis on the general design considerations that motivate each approach. Finally, a set of special topics is discussed, which reflect issues that have become important, especially as arrays are being designed for more high-performance applications of parallel MRI. These topics include concerns about the depth penetration of arrays composed of small elements, the use of adaptive arrays for systems with limited receiver channels, the management of inductive coupling between array elements, and special considerations required at high field strengths. The fundamental limits of spatial encoding using coil arrays are discussed, with a primary emphasis on how the determination of these limits impacts the design of optimized arrays. This review is intended to provide insight into how arrays are currently used for parallel MRI and to place into context the new innovations that are to come. Copyright © 2006 John Wiley & Sons, Ltd. [source] An enhanced-physics-based scheme for the NS-, turbulence modelNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 6 2010William W. Miles Abstract We study a new enhanced-physics-based numerical scheme for the NS-alpha turbulence model that conserves both energy and helicity. Although most turbulence models (in the continuous case) conserve only energy, NS-alpha is one of only a very few that also conserve helicity. This is one reason why it is becoming accepted as the most physically accurate turbulence model. However, no numerical scheme for NS-alpha, until now, conserved both energy and helicity, and thus the advantage gained in physical accuracy by modeling with NS-alpha could be lost in a computation. This report presents a finite element numerical scheme, and gives a rigorous analysis of its conservation properties, stability, solution existence, and convergence. A key feature of the analysis is the identification of the discrete energy and energy dissipation norms, and proofs that these norms are equivalent (provided a careful choice of filtering radius) in the discrete space to the usual energy and energy dissipation norms. Numerical experiments are given to demonstrate the effectiveness of the scheme over usual (helicity-ignoring) schemes. A generalization of this scheme to a family of high-order NS-alpha-deconvolution models, which combine the attractive physical properties of NS-alpha with the high accuracy gained by combining ,-filtering with van Cittert approximate deconvolution. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source] Selective ultrasound-assisted extractions of lipophilic constituents from Betula alleghaniensis and B. papyrifera wood at low temperaturesPHYTOCHEMICAL ANALYSIS, Issue 4 2007J.-M. Lavoie Abstract Betula alleghaniensis and B. papyrifera are widely distributed in the province of Québec (Canada) and, since these trees are valuable exports for the local lumber industry, large amounts of their residual ligneous biomass are available for further exploitation. Betula species are well known for their significant concentrations of triterpenes, some of which were recently discovered to present promising bioactivity. The secondary transformation of birch biomass could therefore become important for many industries, particularly the pharmaceutical industry. In the present study, extracts from birch sawdust were obtained using an optimised ultrasound-assisted extraction in which the careful choice of temperature permitted a selective extraction of the targeted triterpenes. Moreover, compared with the classical Soxhlet method, higher extraction yields were obtained in a shorter time. The lipophilic extracts obtained using dichloromethane as a solvent were analysed by GC-MS and the major compounds identified as lupane-type cyclic triterpenoids accompanied by the non-cyclic triterpene squalene. Numerous aliphatic long-chain fatty acids were also found in the extracts together with phytosterols. Betulonic acid and squalene, the major extract constituents for both B. alleghaniensis and B. papyrifera, are both bioactive molecules. Copyright © 2007 John Wiley & Sons, Ltd. [source] Different amounts of isoflavones in various commercially available soy extracts in the light of gene expression-targeted isoflavone therapyPHYTOTHERAPY RESEARCH, Issue S1 2010Ewa Piotrowska Abstract Isoflavones are plant-derived, biologically active compounds that are commonly used as natural drugs or diet supplements in the treatment of menopausal symptoms and as antioxidants. Recently, it was proposed that genistein (4,,5,7-trihydroxyisoflavone) may be used in the treatment of patients suffering from Sanfilippo disease (mucopolysaccharidosis type III), a severe genetic disorder for which no therapy is available. A pilot clinical study with this novel therapy, called ,gene expression-targeted isoflavone therapy' (GET IT), indicated that a standardized, genistin-rich soy isoflavone extract is effective in the treatment of such patients. Since various isoflavone-containing products are commercially available, the content of the main isoflavones were measured in such products. Extremely different amounts of isoflavones were determined in various products, from 0.13 to 39 mg per tablet. Only some of these products were found to be effective in inhibition of the synthesis of glycosaminoglycans (compounds whose degradation is severely impaired in mucopolysaccharidoses, including Sanfilippo disease) in cultured fibroblasts. Since in GET IT the dose of genistein is calculated per patient's body weight, the amount of this isoflavone in a tablet is crucial for this therapy. Therefore, the results presented in this report indicate that a careful choice of a proper isoflavone extract is necessary for GET IT. Copyright © 2009 John Wiley & Sons, Ltd. [source] Positive ion electrospray ionization mass spectrometry of double-stranded DNA/drug complexesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2001Rajesh Gupta An Erratum has been published for this article in Rapid Communicatons in Mass Spectrometry 16(7) 2002,740,741. Positive ion electrospray ionization mass spectra of 16 base-pair double-stranded (ds)DNA have been obtained with essentially no ions from single-stranded DNA present. Single-stranded DNA was minimized by: (1) careful choice of DNA sequences; (2) the use of a relatively high salt concentration (0.1,M ammonium acetate, pH 8.5), and, (3) a low desolvation temperature (40,°C). Similarly, ESI-MS complexes of dsDNA with cisplatin, daunomycin and distamycin were obtained that contained only negligible amounts of single-stranded DNA. The complexes with daunomycin and distamycin were more stable to strand separation in the gas phase than dsDNA alone. This is in agreement with solution studies and with other recent gas phase results. These data contrast with many earlier ESI-MS studies of dsDNA and DNA/drug complexes in which ions from ssDNA are also normally observed. Copyright © 2001 John Wiley & Sons, Ltd. [source] HISTORY ILLUMINATED: WILLIAM HOLMAN HUNT'S LONDON BRIDGEART HISTORY, Issue 5 2006NANCY ROSE MARSHALL Grappling with the complex problem of how to represent history through the experience of ordinary people, William Holman Hunt's London Bridge of 1864 combined a modern urban crowd scene, a careful choice of depicted location, and an unusual deployment of light effects to create a painting about Victorian perceptions of time itself. By portraying a night-time scene lit by the gas illuminations on the bridge in honour of the wedding of the Prince and Princess of Wales, Hunt drew on the traditional aesthetic of the sublime to create a spectacle of an historic event , a royal marriage , that inspired both wonder and fear. Juxtaposing the flame-lit city with the moonlit Thames at the charged site of London Bridge allowed the artist to set in play the common Victorian framework one might term the ,moralizing sublime'. This pervasive mode of thought involved reading the mighty strivings of man and the modern industrial city as puny, transitory glimmers in comparison with the infinite onward rush of time; paradoxically, it also permitted the wilful overlooking of any negative yet ephemeral consequences of modernity. These ideas were underscored by the original exhibition of London Bridge with another work by Hunt in which light plays a key role in producing meaning: The Afterglow in Egypt. [source] Predicting potential impacts of environmental flows on weedy riparian vegetation of the Hawkesbury,Nepean River, south-eastern AustraliaAUSTRAL ECOLOGY, Issue 5 2000Jocelyn Howell Abstract Remnants of native riparian vegetation on the floodplain of the Hawkesbury,Nepean River near Sydney, have significant conservation value, but contain a large component of weeds (i.e. exotic species that have become naturalized). A proposal for the introduction of environmental flows required an assessment of potential impacts on 242 native and 128 exotic species recorded along 215 km of the river. The likely effects of frequency, season, depth and duration of inundation were considered in relation to habitat, dispersal season and tolerance to waterlogging. Overseas studies provided only limited information applicable to the study area; however, comparisons with similarly highly modified riparian habitats in New Zealand were instructive. Depth and season of inundation appear to be the variables with the greatest potential for differential effects on weeds and native plants. Because of likely spread of propagules and enhancement of growth under the present nutrient-enriched conditions, environmental flows that would cause more frequent flooding to higher levels of the riparian zone were judged to be of more benefit to weed species than native species, unless supported by bushland management including weeding. Predictions were limited by incomplete data on Hawkesbury,Nepean species, but two types of environmental flow were judged to be potentially beneficial for native water-edge plants, and worth testing and monitoring: first, flows that maintain continuous low-level flow in the river, and second, higher level environmental flows restricted to the river-edge habitat in autumn (the season in which a greater proportion of native species than weed species are known to disperse propagules). In summary, the presence of environmental weeds in riparian vegetation constrain the potential for environmental flows to improve river health. However, with ongoing monitoring, careful choice of water level and season of flow may lead to environmental flows that add to our knowledge, and benefit riparian vegetation along with other river system components. [source] Determinants of response to first HAART regimen in antiretroviral-naïve patients with an estimated time since HIV seroconversionHIV MEDICINE, Issue 1 2006R Thiébaut Objective To study the determinants of immunological and virological response to highly active antiretroviral therapy (HAART) in naïve patients, adjusting for time since HIV-1 seroconversion. Design Data from HIV-cohort studies where dates of seroconversion have been reliably estimated. Methods In previously untreated patients, short- and long-term marker responses from HAART initiation (three or more antiretroviral drugs) to the end of follow-up or any treatment modification were considered using mixed effects models accounting for undetectable HIV viral load and informative dropout. Results In total, 943 patients were treated with a first HAART regimen for a median of 29 months. In adjusted analyses, compared with a reference group of homosexual men without AIDS initiating treatment 4 years after seroconversion, injecting drug users (IDUs) were treated at similar CD4 and HIV RNA levels but had poorer short-term virological response (2.54 vs 2.13 log10 HIV-1 RNA copies/mL at 1.5 months, P=0.03) and poorer long-term immunological response (522 vs 631 cells/,L at 24 months, P<0.0001). Although individuals with AIDS at HAART initiation had lower CD4 counts (206 vs 382 cells/,L, P<0.0001), their immunological responses were similar to those of individuals without AIDS. Similarly, individuals further from seroconversion started HAART at lower CD4 counts (e.g. 311 vs 382 cells/,L at vs before 9 years from seroconversion, P<0.0001), but had similar CD4 responses. However, they experienced poorer long-term virological response (0.67 log10 copies/mL/year smaller decline, P<0.0001) compared to those treated before 9 years from seroconversion. Conclusion Taking into account the time elapsed since seroconversion, this study suggests that careful choices of initial treatment should be made and intensive follow-up carried out in high-risk subgroups such as IDUs who have poorer responses. [source] Affinity-enhanced protein partitioning in decyl ,- D -glucopyranoside two-phase aqueous micellar systemsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2005Henry Lam Abstract Liquid,liquid extraction in two-phase aqueous complex-fluid systems has been proposed as a scalable, versatile, and cost-effective purification method for the downstream processing of biotechnological products. In the case of two-phase aqueous micellar systems, careful choices of the phase-forming surfactants or surfactant mixtures allow these systems to separate biomolecules based on size, hydrophobicity, charge, or specific affinity. In this article, we investigate the affinity-enhanced partitioning of a model affinity-tagged protein,green fluorescent protein fused to a family 9 carbohydrate-binding module (CBM9-GFP),in a two-phase aqueous micellar system generated from the nonionic surfactant n -decyl ,- D -glucopyranoside (C10G1), which acts simultaneously as the phase-former and the affinity ligand. In this simple system, CBM9-GFP was extracted preferentially into the micelle-rich phase, despite the opposing tendency of the steric, excluded-volume interactions operating between the protein and the micelles. We obtained more than a sixfold increase (from 0.47 to 3.1) in the protein partition coefficient (Kp), as compared to a control case where the affinity interactions were "turned off" by the addition of a competitive inhibitor (glucose). It was demonstrated conclusively that the observed increase in Kp can be attributed to the specific affinity between the CBM9 domain and the affinity surfactant C10G1, suggesting that the method can be generally applied to any CBM9-tagged protein. To rationalize the observed phenomenon of affinity-enhanced partitioning in two-phase aqueous micellar systems, we formulated a theoretical framework to model the protein partition coefficient. The modeling approach accounts for both the excluded-volume interactions and the affinity interactions between the protein and the surfactants, and considers the contributions from the monomeric and the micellar surfactants separately. The model was shown to be consistent with the experimental data, as well as with our current understanding of the CBM9 domain. © 2005 Wiley Periodicals, Inc. [source] Image analysis and quantification in lung tissueCLINICAL & EXPERIMENTAL ALLERGY, Issue 3 2001W.I. De Boer On 9,10 September 1999, an international workshop on image analysis and quantification in lung tissue was held at the Leiden University Medical Center, Leiden, The Netherlands. Participants with expertise in pulmonary and/or pathology research discussed the validity and applicability of techniques used for quantitative examination of inflammatory cell patterns and gene expression in bronchial or parenchymal tissue in studies focusing on asthma and chronic obstructive pulmonary disease (COPD). Differences in techniques for tissue sampling and processing, immunohistochemistry, cell counting and densitometry are hampering the comparison of data between various laboratories. The main goals of the workshop were to make an inventory of the techniques that are currently available for each of these aspects, and in particular to address the validity and unresolved problems of using digital image analysis (DIA) as opposed to manual scoring methods for cell counting and assessment of gene and protein expression. Obviously, tissue sampling and handling, fixation and (immunohistochemical) staining, and microscope settings, are having a large impact on any quantitative analysis. In addition, careful choices will have to be made of the commercially available optical and recording systems as well as the application software in order to optimize quantitative DIA. Finally, it appears to be of equal importance to reach consensus on which histological areas are to be analysed. The current proceedings highlight recent advances and state of the art knowledge on digital image analysis for lung tissue, and summarize the established issues and remaining questions raised during the course of the workshop. [source] | ||||||||||||||||