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Principles Used (principle + used)

Distribution by Scientific Domains

Medical Sciences	40%
Chemistry	40%

Selected Abstracts

Is the Precautionary Principle Used to Cover Up Ignorance?

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2004
Jouko Tuomisto
Some caveats are presented in this commentary, and some principles proposed for improved risk assessment/risk management procedures. Improvement is especially needed in such cases where the risks of different management options must be compared. [source]

Nanomechanics of single keratin fibres: A Raman study of the ,-helix ,,-sheet transition and the effect of water

JOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2007
Raphaël Paquin
Abstract The use of micro-Raman spectroscopy, through chemical-bond, nano-scale probes, allows the changes in conformations (,-helix ,,-sheet), chain orientation, breakage of disulfide bonds (20%) and the increase of intra- and inter-chain distances during the application of stress to be distinguished. The combination of micro-Raman spectroscopy and a Universal Fibre Tester allows a quantitative measurement of the extension of chemical bonds in the peptide chain during loading. The nano-structural transformations of keratin during strain of human hair in a dry environment (40,60% relative humidity) and saturated with water have been studied. Water permits the sliding of the chains and decreases the bond energy of the hair. Spectral analyses and 2D correlation are two coherent and independent methods to follow the structural nano-mechanical (Raman) and micro-mechanical (strain/stress) analyses, and confirm the validity of the experimental results, tools and principles used, as well as the agreement with the structural model of keratin fibres described by Chapman and Hearle. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Cognitive factors affecting student understanding of geologic time

JOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 4 2003
Jeff Dodick
A critical element of the earth sciences is reconstructing geological structures and systems that have developed over time. A survey of the science education literature shows that there has been little attention given to this concept. In this study, we present a model, based on Montagnero's (1996) model of diachronic thinking, which describes how students reconstruct geological transformations over time. For geology, three schemes of diachronic thinking are relevant: 1. Transformation, which is a principle of change; in geology it is understood through actualistic thinking (the idea that present proceeses can be used to model the past). 2. Temporal organization, which defines the sequential order of a transformation; in geology it is based on the three-dimensional relationship among strata. 3. Interstage linkage, which is the connections between successive stages of a transformation; in geology it is based on both actualism and causal reasoning. Three specialized instruments were designed to determine the factors which influence reconstructive thinking: (a) the GeoTAT which tests diachronic thinking skills, (b) the TST which tests the relationship between spatial thinking and temporal thinking, and (c) the SFT which tests the influence of dimensional factors on temporal awareness. Based on the model constructed in this study we define the critical factors influencing reconstructive thinking: (a) the transformation scheme which influences the other diachronic schemes, (b) knowledge of geological processes, and (c) extracognitive factors. Among the students tested, there was a significant difference between Grade 9,12 students and Grade 7,8 students in their ability to reconstruct geological phenomena using diachronic thinking. This suggests that somewhere between Grades 7 and 8 it is possible to start teaching some of the logical principles used in geology to reconstruct geological structures. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 415,442, 2003 [source]

Promoting Physical Activity Among Youth Through Community-Based Prevention Marketing

JOURNAL OF SCHOOL HEALTH, Issue 5 2010
Carol A. Bryant PhD
BACKGROUND: Community-based prevention marketing (CBPM) is a program planning framework that blends community-organizing principles with a social marketing mind-set to design, implement, and evaluate public health interventions. A community coalition used CBPM to create a physical activity promotion program for tweens (youth 9,13 years of age) called VERBÔ Summer Scorecard. Based on the national VERBÔ media campaign, the program offered opportunities for tweens to try new types of physical activity during the summer months. METHODS: The VERBÔ Summer Scorecard was implemented and monitored between 2004 and 2007 using the 9-step CBPM framework. Program performance was assessed through in-depth interviews and a school-based survey of youth. RESULTS: The CBPM process and principles used by school and community personnel to promote physical activity among tweens are presented. Observed declines may become less steep if school officials adopt a marketing mind-set to encourage youth physical activity: deemphasizing health benefits but promoting activity as something fun that fosters spending time with friends while trying and mastering new skills. CONCLUSIONS: Community-based programs can augment and provide continuity to school-based prevention programs to increase physical activity among tweens. [source]

Design of a minimal protein oligomerization domain by a structural approach

PROTEIN SCIENCE, Issue 12 2000
Peter Burkhard
Abstract Because of the simplicity and regularity of the ,-helical coiled coil relative to other structural motifs, it can be conveniently used to clarify the molecular interactions responsible for protein folding and stability. Here we describe the de novo design and characterization of a two heptad-repeat peptide stabilized by a complex network of inter- and intrahelical salt bridges. Circular dichroism spectroscopy and analytical ultracentrifugation show that this peptide is highly ,-helical and 100% dimeric under physiological buffer conditions. Interestingly, the peptide was shown to switch its oligomerization state from a dimer to a trimer upon increasing ionic strength. The correctness of the rational design principles used here is supported by details of the atomic structure of the peptide deduced from X-ray crystallography. The structure of the peptide shows that it is not a molten globule but assumes a unique, native-like conformation. This de novo peptide thus represents an attractive model system for the design of a molecular recognition system. [source]