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Rigorous Description (rigorous + description)

Distribution by Scientific Domains

Chemistry	33%

Selected Abstracts

Solenoidal microcoil design,Part II: Optimizing winding parameters for maximum signal-to-noise performance

CONCEPTS IN MAGNETIC RESONANCE, Issue 3 2001
Kevin R. Minard
Abstract In high-field proton NMR, the signal-to-noise ratio (SNR) achieved with a close-fitting solenoidal microcoil is adversely affected by radio frequency (RF) losses in the coil, its leads, the capacitor used to tune it, and finally, the sample. In Part II, a rigorous description of these various losses is presented, and their severity is related to the details of coil design. Results not only provide a rational basis for defining a microcoil's optimal wire diameter and the number of turns, but also for evaluating how the SNR varies with coil size and NMR frequency in high-field proton NMR studies involving either conducting or non-conducting samples. © 2001 John Wiley & Sons, Inc. Concepts Magn Reson 13: 190,210, 2001 [source]

Thermal stability of vaccines

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2003
Duane T. Brandau
Abstract Worldwide vaccination programs against infectious diseases and toxins are estimated to save approximately 3 million lives yearly. Tragically, however, another 3 million individuals (primarily children) die of vaccine-preven diseases. A significant portion of this problem results from the thermal instability of many of the currently used vaccines. This review argues that modern methods of physical and chemical analysis permit for the first time characterization of the degradative pathways of thermally labile vaccines. A rigorous description of these pathways permit a more rational and systematic approach to the stabilization of vaccines. A direct result of the replacement of currently employed, primarily empirical, approaches to vaccine stabilization with a more molecular-based methodology should be the development of more universally available vaccinations against life-threatening diseases. This has the potential to have a dramatic impact on world health. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:218,231, 2003 [source]

Hybrid mode matching and auxiliary sources technique for horn antenna analysis

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007
S. G. Diamantis
Abstract A hybrid technique for the analysis of horn antennas is described based on a rigorous description of the horn aperture-free space discontinuity. The transition from the feeding waveguide to the radiating aperture is analyzed by using the mode matching technique (MMT) employing a stepped-waveguide approach. The discontinuity between the horn aperture and the free space is modeled by combining the method of auxiliary sources with the MMT for the stepped waveguide section. Results for the input standing wave ratio are given and compared with the available measurements, which demonstrate the very good performance of the method. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 734,739, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22233 [source]

Refined structure of Pyrococcus furiosus ornithine carbamoyltransferase at 1.87,A

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2003
Jan Massant
Using synchrotron radiation, X-ray data have been collected from Pyrococcus furiosus ornithine carbamoyltransferase (Pfu OTCase) to a maximal resolution of 1.87,Å, allowing the refinement of a previous structure at 2.7,Å [Villeret et al. (1998), Proc. Natl Acad. Sci. USA, 95, 2801,2806]. Thanks to the high resolution of this refined structure, two sulfate ions and 191 water molecules could be localized directly from the electron-density maps. The identification of these molecules allowed a more rigorous description of the active site and the identification of residues involved in binding carbamoyl phosphate. The improved quality of the model resulted in a better definition of several loops and the various interfaces. The dodecameric protein is composed of four catalytic trimers disposed in a tetrahedral manner. The extreme thermal stability of Pfu OTCase is mainly the result of the strengthening of the intersubunit interactions in a trimer and oligomerization of the trimers into a dodecamer. Interfaces between monomers in a catalytic trimer are characterized by an increase in ion-pair networks compared with mesophilic OTCases. However, the interfaces between catalytic trimers in the dodecameric oligomer are mainly hydrophobic and also involve aromatic,aromatic and cation,, interactions. [source]

Topography and interactions of the arytenoid and cricoid articular facets: Implications for vocal process positional shifts

CLINICAL ANATOMY, Issue 3 2004
Kenneth X. Probst
Abstract Using new computer applications and digital technologies, we provide a rigorous description and realistic illustrations of the arytenoid-on-the cricoid rotations. We also provide the articular facet topography and interactions that underlay those rotations and the concomitant vocal process positional shifts. The thyroid cartilage and all soft tissues were removed from three excised, preserved, normal, adult human larynges without disturbing the crico-arytenoid (CA) articular capsule. Three CA assemblies were thus prepared and used to digitize arytenoid rotations and vocal process positional shifts, and, after disarticulation, also the surface contour of the arytenoid and cricoid facets, and the cricoid lumen margin. The digitized data served to computer generate 2D and 3D graphic visualizations of the vocal process positional shifts, of the topography of the facets, and of the facet motion sequences that show that the anteroposteriorly concave arytenoid facet slides and conjunctly rotates on the anteroposteriorly convex cricoid facet. Visual details of all graphic representations and facet motion sequences were essentially identical across the three assemblies. Then, based on the computer generated data obtained from the largest of the CA assemblies, 3D, realistic, and hand-drawn images were made that illustrate the directions in which the arytenoids can rotate and the vocal processes concomitantly shift positions. Results indicate that when the arytenoids rotate by sliding from anterior to posterior on the cricoid facets about a primary axis of motion aligned from medial, posterior, and superior, to lateral, anterior, and inferior, their vocal processes shift positions along a plane obliquely oriented from anterior and medial, to posterior and lateral, and from inferior and medial, to superior and lateral. Clin. Anat. 17:206,213, 2004. © 2004 Wiley-Liss, Inc. [source]

Localised agricultural knowledge and food production in sub-Saharan Africa

INTERNATIONAL SOCIAL SCIENCE JOURNAL, Issue 187 2006
Lazare Séhouéto
In Benin localised agricultural knowledge is produced or taken on board by the farmers according to their specific cognitive frames and social logic. It is therefore important to analyse them in their complexity. The analysis of farmers' knowledge as to the choice of associating or not associating various crops shows that, while the reasons advanced in the first case are above all ecological (more than 80 per cent of the responses), those put forward in the second are at once economic and ecological. Yet the farming calendar is not merely an adaptation to weather and climatic requirements: it brings together the implications of politics, economics, religion, and natural constraints. In this article I argue that to promote this localised knowledge which helps the majority of men and women who live south of the Sahara to survive, scientists must make more rigorous descriptions and interpretations of localised knowledge, in order to avoid the risk of becoming trapped in folklore or the mystical. [source]