Right Position (right + position)

Distribution by Scientific Domains


Selected Abstracts


Thermus thermophilus Glycosynthases for the Efficient Synthesis of Galactosyl and Glucosyl ,-(1,3) - Glycosides

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2005
Jullien Drone
Abstract Inverting mutant glycosynthases were designed according to the Withers strategy, starting from wild-type Thermus thermophilus retaining Tt-,-Gly glycosidase. Directed mutagenesis of catalytic nucleophile glutamate 338 by alanine, serine, and glycine afforded the E338A, E338S, and E338G mutant enzymes, respectively. As was to be expected, the mutants were unable to catalyze the hydrolysis of the transglycosidation products. In agreement with previous results, the E338S and E338G catalysts were much more efficient than E338A. Moreover, our results showed that these enzymes were inactive in the hydrolysis of the ,- D -glycopyranosyl fluorides used as donors, and so suitable experimental conditions, under which the rate of spontaneous hydrolysis of the donor was considerably lower than that of enzymatic transglycosidation, provided galactosyl and glucosyl ,-(1,3) - glycosides in yields of up to 90,%. The structure of native Tt-,-Gly available in the Protein Data Bank offers a good basis for interpretation of our results by means of molecular modeling. Thus, in the case of the E338S mutant, a lower energy of the system was obtained when the donor and the acceptor were in the right position to form the ,-(1,3) - glycosidic bond. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]


g_membed: Efficient insertion of a membrane protein into an equilibrated lipid bilayer with minimal perturbation

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 11 2010
Maarten G. Wolf
Abstract To efficiently insert a protein into an equilibrated and fully hydrated membrane with minimal membrane perturbation we present a computational tool, called g_membed, which is part of the Gromacs suite of programs. The input consists of an equilibrated membrane system, either flat or curved, and a protein structure in the right position and orientation with respect to the lipid bilayer. g_membed first decreases the width of the protein in the xy -plane and removes all molecules (generally lipids and waters) that overlap with the narrowed protein. Then the protein is grown back to its full size in a short molecular dynamics simulation (typically 1000 steps), thereby pushing the lipids away to optimally accommodate the protein in the membrane. After embedding the protein in the membrane, both the lipid properties and the hydration layer are still close to equilibrium. Thus, only a short equilibration run (less then 1 ns in the cases tested) is required to re-equilibrate the membrane. Its simplicity makes g_membed very practical for use in scripting and high-throughput molecular dynamics simulations. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source]


Sperm transfer during mating in the pharaoh's ant, Monomorium pharaonis

PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2006
D. ALLARD
Abstract Sperm transfer in the pharaoh's ant Monomorium pharaonis (L.) is studied by making longitudinal sections through the gasters of mating pairs fixed in copula. Sperm is transferred inside a spermatophore similar to those found in two other ants, Diacamma sp. from Japan and Carebara vidua. Sharp teeth-ridges are present on the penis valves and, during copulation, these teeth make contact with a thick and soft cuticular layer covering the bursa copulatrix. This ensures an attachment long enough for the successful transfer of the spermatophore to the right position inside the female oviduct. The thick cuticle also protects the queen from serious damage by the male's sharp claspers. After a first successful copulation, sperm is still present inside the male's seminal vesicles, suggesting that males can mate multiply. Additional experiments, where single, initially virgin males are presented to several virgin females, confirm this. [source]


Capturing Government Policy on the Left,Right Scale: Evidence from the United Kingdom, 1956,2006

POLITICAL STUDIES, Issue 4 2009
Armèn Hakhverdian
The left,right scheme is the most widely used and parsimonious representation of political competition. Yet, long time series of the left,right position of governments are sparse. Existing methods are of limited use in dynamic settings due to insufficient time points which hinders the proper specification of time-series regressions. This article analyses legislative speeches in order to construct an annual left,right policy variable for Britain from 1956 to 2006. Using a recently developed content analysis tool, known as Wordscores, it is shown that speeches yield valid and reliable estimates for the left,right position of British government policy. Long time series such as the one proposed in this article are vital to building dynamic macro-level models of politics. This measure is cross-validated with four independent sources: (1) it compares well to expert surveys; (2) a rightward trend is found in post-war British government policy; (3) Conservative governments are found to be more right wing in their policy outputs than Labour governments; (4) conventional accounts of British post-war politics support the pattern of government policy movement on the left,right scale. [source]


Neuromagnetic signals associated with reading a kanji character formed by combining two kanji radicals

JAPANESE PSYCHOLOGICAL RESEARCH, Issue 1 2000
Toshiaki Imada
To find out which brain regions are responsible for the mental construction and recognition of a kanji character initiated by visually presented kanji radicals, rather than by information retained in the memory, a left hen radical and the corresponding right tsukuri radical were simultaneously presented randomly to either the left or right visual field of seven subjects. Thirty left hen radicals and the corresponding right tsukuri radicals were prepared as stimuli; this combination formed over 500 real or pseudo kanji characters. Instead of their usual left and right positions, the left hen radical was always presented above the right tsukuri radical. As quickly and correctly as possible, the subjects released a key when two kanji radicals constituted a single real kanji character and released another key otherwise. We recorded neuromagnetic responses as well as accuracy and reaction time. Left visual field superiority was observed as regards accuracy. This is in good agreement with previous neuropsychological results. Equivalent current dipoles were localized mainly in the left and/or right occipitotemporal regions (ventral visual pathways), the bilateral occipitoparietal regions (dorsal visual pathways) including the supramarginal region, and the areas surrounding the left superior temporal cortex. We suggest that these regions are related to reading and the mental construction of a kanji character from its radicals. [source]


A new potential field method for mobile robot path planning in the dynamic environments

ASIAN JOURNAL OF CONTROL, Issue 2 2009
Lu Yin
Abstract A new potential field method for mobile robot path planning is proposed in this paper. At present, most potential field methods are designed to be applied in the stationary environment, and several improved potential functions have brought in the velocity factors in the dynamic circumstances. Based on the consideration that the moving trend of the robot in the dynamic environments is also necessary to produce more reasonable path, this paper defines new attractive potential function with respect to the relative position, velocity, and acceleration between the robot and the goal, as well as the repulsive potential function with respect to the relative positions, velocities, and accelerations between the robot and the obstacles. The virtual forces are calculated to make the robot plan its motion, not only with right positions, but also with suitable velocities. Furthermore, the robot will keep a similar moving trend with the goal and contrary trends with the obstacles. Finally, some methodic simulations are carried out to validate and demonstrate the effectiveness of the new potential field method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]