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Comparative Discussion (comparative + discussion)
Selected AbstractsA comparative study of 3D scanning in engineering, product and transport design and fashion design educationCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 3 2009A. Kus Abstract The aim of this paper is to evaluate the use of three-dimensional (3D) scanning technologies for design and engineering courses. This paper will provide a comparative discussion of the current 3D scanning technologies; and then describes three experimental studies in engineering, transport design and fashion design. Using 3D scanner technology the experiments tested the transferral of a variety of different data from scanned organic 3D shapes to 3D CAD packages for learning and teaching in undergraduate education. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 263,271, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20213 [source] Shuffling genes around in hot environments: the unique DNA transporter of Thermus thermophilusFEMS MICROBIOLOGY REVIEWS, Issue 3 2009Beate Averhoff Abstract Natural transformation permits the transport of DNA through bacterial membranes and represents a dominant mode for the transfer of genetic information between bacteria and between microorganisms of distant evolutionary lineages and even between members of different domains. This phenomenon, known as horizontal, or lateral, gene transfer, has been a major force for genome plasticity over evolutionary history, and is largely responsible for the spread of fitness-enhancing traits, including antibiotic resistance and virulence factors. In particular, for adaptation of prokaryotes to extreme environments, lateral gene transfer seems to have played a crucial role. Here, we present a survey of the natural transformation machinery of the thermophile Thermus thermophilus HB27. A tentative model of the transformation machinery comprising of components similar to proteins of type IV pili and type II secretion systems is presented. A comparative discussion of the subunits and the structure of the DNA translocator and the underlying mechanism of transfer of free DNA in T. thermophilus highlights conserved and unique features of the DNA translocator in T. thermophilus. We hypothesize that the extraordinary broad substrate specificity and the high efficiency of the T. thermophilus DNA uptake system is of major importance for thermoadaptation and interdomain DNA transfer in hot environments. [source] Comparative assessment of two distributed watershed models with application to a small watershedHYDROLOGICAL PROCESSES, Issue 11 2006Latif Kalin Abstract Distributed watershed models are beneficial tools for the assessment of management practices on runoff and water-induced erosion. This paper evaluates, by application to an experimental watershed, two promising distributed watershed-scale sediment models in detail: the Kinematic Runoff and Erosion (KINEROS-2) model and the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model. The physics behind each model are to some extent similar, though they have different watershed conceptualizations. KINEROS-2 was calibrated using three rainfall events and validated over four separate rainfall events. Parameters estimated by this calibration process were adapted to GSSHA. With these parameters, GSSHA generated larger and retarded flow hydrographs. A 30% reduction in both plane and channel roughness in GSSHA along with the assumption of Green-Ampt conductivity KG-A = Ks, where Ks is the saturated conductivity, resulted in almost identical hydrographs. Sediment parameters not common in both models were calibrated independently of KINEROS-2. A comparative discussion of simulation results is presented. Even though GSSHA's flow component slightly overperformed KINEROS-2, the latter outperformed GSSHA in simulations for sediment transport. In spite of the fact that KINEROS-2 is not geared toward continuous-time simulations, simulations performed with both models over a 1 month period generated comparable results. Copyright © 2006 John Wiley & Sons, Ltd. [source] Application of a single-reflection collimating multilayer optic for X-ray diffraction experiments employing parallel-beam geometryJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2008M. Wohlschlögel Instrumental aberrations of a parallel-beam diffractometer equipped with a rotating anode X-ray source, a single-reflection collimating multilayer optic and a parallel-plate collimator in front of the detector have been investigated on the basis of standard measurements (i.e. employing stress- and texture-free isotropic powder specimens exhibiting small or negligible structural diffraction line broadening). It has been shown that a defocusing correction, which is a major instrumental aberration for diffraction patterns collected with divergent-beam (focusing) geometries, is unnecessary for this diffractometer. The performance of the diffractometer equipped with the single-reflection collimating multilayer optic (single-reflection mirror) is compared with the performance of the diffractometer equipped with a Kirkpatrick,Baez optic (cross-coupled Göbel mirror) on the basis of experimental standard measurements and ray-tracing calculations. The results indicate that the use of the single-reflection mirror provides a significant gain in photon flux and brilliance. A high photon flux, high brilliance and minimal divergence of the incident beam make the setup based on the single-reflection mirror particularly suitable for grazing-incidence diffraction, and thus for the investigation of very thin films (yielding low diffracted intensities) and of stress and texture (requiring the acquisition of large measured data sets, corresponding to the variation of the orientation of the diffraction vector with respect to the specimen frame of reference). A comparative discussion of primary optics which can be used to realise parallel-beam geometry shows the range of possible applications of parallel-beam diffractometers and indicates the virtues and disadvantages of the different optics. [source] Identification of van Hove singularities in the GaN dielectric function: a comparison of the cubic and hexagonal phasePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2009C. Cobet Abstract We present a detailed analysis of interband transition structures in the dielectric function of GaN. The dielectric function of the stable wurtzite and the metastable zinc blende phase were determined by means of synchrotron spectroscopic ellipsometry in the spectral range between 3 eV and 20 eV where the most significant structures of the dielectric function are located. In the hexagonal case, both the ordinary and extraordinary dielectric tensor component was measured on GaN films with M -plane/[1 00] orientation. In a comparative discussion of the two hexagonal tensor components and the zinc blende dielectric function, all prominent absorption structures were assigned to specific interband transitions at high symmetry points in the Brillouin zone. The assignment considers the individual dipole transition probabilities depending on the crystal symmetry and the geometry of the measurement. Furthermore, a detailed theoretical band-to-band analysis of dielectric function features, published by Lambrecht et al. [1], was considered. In conclusion, we suggest a new labeling of absorption structures as used in classical III,V materials like GaAs, which reflects the origin of transition structures from specific points in the respective Brillouin zones. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||