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Active Research (active + research)

Distribution by Scientific Domains

Earth and Environmental Science	28%

Selected Abstracts

Convective-scale assimilation of radar data: progress and challenges

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 613 2005
Juanzhen Sun
Abstract Active research has been carried out in recent years to assimilate high-resolution observations into numerical models to improve precipitation forecasting. Considerable progress has been made although great scientific and technological challenges still exist. This paper reviews techniques used in convective-scale data assimilation research. Experiences in the assimilation of radar observations into high-resolution numerical models are presented. A number of future challenges in convective-scale data assimilation are discussed. Copyright © 2005 Royal Meteorological Society [source]

Effects of terrain smoothing on topographic shielding correction factors for cosmogenic nuclide-derived estimates of basin-averaged denudation rates

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2009
Kevin P. Norton
Abstract Estimation of spatially averaged denudation rates from cosmogenic nuclide concentrations in sediments depends on the surface production rates, the scaling methods of cosmic ray intensities, and the correction algorithms for skyline, snow and vegetation shielding used to calculate terrestrial cosmogenic nuclide production. While the calculation of surface nuclide production and application of latitude, altitude and palaeointensity scaling algorithms are subjects of active research, the importance of additional correction for shielding by topographic obstructions, snow and vegetation is the subject of ongoing debate. The derivation of an additional correction factor for skyline shielding for large areas is still problematic. One important issue that has yet to be addressed is the effect of the accuracy and resolution of terrain representation by a digital elevation model (DEM) on topographic shielding correction factors. Topographic metrics scale with the resolution of the elevation data, and terrain smoothing has a potentially large effect on the correction of terrestrial cosmogenic nuclide production rates for skyline shielding. For rough, high-relief landscapes, the effect of terrain smoothing can easily exceed analytical errors, and should be taken into account. Here we demonstrate the effect of terrain smoothing on topographic shielding correction factors for various topographic settings, and introduce an empirical model for the estimation of topographic shielding factors based on landscape metrics. Copyright © 2008 John Wiley and Sons, Ltd. [source]

The creation of an international audit and database of equine colic surgery: Survey of attitudes of surgeons

EQUINE VETERINARY JOURNAL, Issue 4 2008
T. S. MAIR
Summary Reasons for performing study: Currently, there is a lack of available evidence-based data concerning the optimum treatments for horses affected by different types of colic and this precludes the application of clinical audit in this area. In order to accumulate such data, a large-scale, multicentre database of the outcomes of colic surgery is proposed. The attitudes of surgeons is an important consideration in determining the feasibility of developing this database. Objectives: To assess attitudes and opinions of equine surgeons concerning clinical audit and to assess the perceived advantages and problems of setting up a large-scale international audit/database of colic surgery. Methods: Interviews were conducted with 30 equine surgeons (large animal/equine surgeons who are diplomates of either the American College of Veterinary Surgeons or the European College of Veterinary Surgeons). Questionnaires were sent by e-mail to 98 equine surgeons. Results: Face to face interviews were conducted (n = 30) and 43/98 completed questionnaires received (44%). The results of the 2 techniques were very similar. There was generally a high level of interest in the development of a large scale database of colic surgery, but perceived problems included time to collect and submit data, and confidentiality issues. A minority of surgeons reported that they were undertaking any form of specific monitoring of the results of colic surgery within their hospitals. Conclusions: There is a good level of interest among equine surgeons to develop a large scale database of colic surgery and most would be willing to contribute data from their own hospitals provided that data collection is quick and easy, and that confidentiality is maintained. Potential relevance: A large scale audit and database would provide relevant information to equine surgeons concerning the current success and complication rates of colic surgery. Such evidence-based data could be used in clinical audits within individual equine hospitals. The data would also be useful to identify trends within the discipline and could highlight areas that would benefit from active research. [source]

Electrical Conductance in Biological Molecules

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010
M. Waleed Shinwari
Abstract Nucleic acids and proteins are not only biologically important polymers. They have recently been recognized as novel functional materials surpassing conventional materials in many aspects. Although Herculean efforts have been undertaken to unravel fine functioning mechanisms of the biopolymers in question, there is still much more to be done. Here the topic of biomolecular charge transport is presented with a particular focus on charge transfer/transport in DNA and protein molecules. The experimentally revealed details, as well as the presently available theories, of charge transfer/transport along these biopolymers are critically reviewed and analyzed. A summary of the active research in this field is also given, along with a number of practical recommendations. [source]

Comparisons and connections between mean field dynamo theory and accretion disc theory

ASTRONOMISCHE NACHRICHTEN, Issue 1 2010
E.G. Blackman
Abstract The origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century. Magnetohydrodynamic turbulence makes both problems highly nonlinear, so both subjects have benefitted from numerical simulations.However, understanding the key principles and practical modeling of observations warrants testable semi-analytic mean field theories that distill the essential physics. Mean field dynamo (MFD) theory and alpha-viscosity accretion disc theory exemplify this pursuit. That the latter is a mean field theory is not always made explicit but the combination of turbulence and global symmetry imply such. The more commonly explicit presentation of assumptions in 20th century textbook MFDT has exposed it to arguably more widespread criticism than incurred by 20th century alpha-accretion theory despite complementary weaknesses. In the 21st century however, MFDT has experienced a breakthrough with a dynamical saturation theory that consistently agrees with simulations. Such has not yet occurred in accretion disc theory, though progress is emerging. Ironically however, for accretion engines, MFDT and accretion theory are presently two artificially uncoupled pieces of what should be a single coupled theory. Large scale fields and accretion flows are dynamically intertwined because large scale fields likely play a key role in angular momentum transport. I discuss and synthesize aspects of recent progress in MFDT and accretion disc theory to suggest why the two likely conspire in a unified theory (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

A Century of Biometrical Genetics

BIOMETRICS, Issue 3 2000
Robert C. Elston
Summary. We briefly review the major contribution of biometrics to genetics over the last century (population genetic models, familial correlations, segregation analysis, and gene mapping) and current areas of active research and then speculate about what problems will be tackled in the next century. [source]

Ferrocenyl-Ended Thieno,Vinylene Oligomers: Donor,Acceptor Polarization and Mixed-Valence Properties with Emphasis on the Raman Mapping of Localized-to-Delocalized Transitions

CHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2009
Juan Casado Dr.
Abstract What's your role? New oligothiophene,vinylene compounds have been synthesized to study the role of the conjugated chain in two different cases (see scheme; MV=mixed valence). The electronic and molecular structures were analyzed by means of electronic, X-ray photoelectron, and Raman spectroscopy, together with thermo spectroscopy, electrochemistry, and DFT calculations. New oligothiophene,vinylene compounds have been synthesized in order to study the role of the conjugated chain in two different cases: 1),when push,pull action operates between an electron-donor and an electron-acceptor group at the ends of the thiophene,vinylene conjugated chain, and 2),when mixed-valence action is induced by single oxidation of the same chain functionalized at both terminal positions with ferrocene groups leading to competition between the donor groups. The electronic and molecular structures are analyzed by means of electronic, X-ray photoelectron and Raman spectroscopies, together with thermospectroscopy, electrochemistry and density functional theory calculations. The cyclic voltammetry processes have been followed by spectrochemistry. It is shown that the radical cation of the diferrocenyl derivative is a class,III mixed-valence system (i.e., fully delocalized) according to its Raman spectrum. Moreover, by Raman thermo-spectroscopy the thermal transition of this radical cation from a delocalized (class,III, room temperature) to a localized (class,II, ,160,°C) state is scanned. In all cases the Raman study is paralleled by an electronic absorption spectroscopic analysis. Structure,property relationships are proposed for molecules of two important fields of very active research as that of the non-linear optics (i.e., organic optoelectronic) and that of the mixed-valence systems (i.e., charge-transfer processes). [source]