Charge transport in molecular and extended systems is discussed with special reference to the mixing of covalent and ionic states and the evolution of this mixing with time. The formalism allows the electron to acquire an extra phase when it moves from one site to the next so that a hopping limit can be reached where the electron transfers with a random phase. The equations of motion are solved for both quantum mechanical and classical dynamics. An appendix discusses a classical representation of orbital occupancies in a manner consistent with the Pauli exclusion principle.
The present invention relates to a pharmaceutical cream composition for topical application for the treatment of skin disorders and skin diseases, comprising 1-6 wt.% Dead Sea Mud as an active ingredient. Said composition is for use in treating skin disorders and skin diseases such as psoriasis, saborrehic dermatitis, xerosis, atopic dermatitis, eczema, diaper rash, skin burns of state I and sensitive skin. Said cream composition is also for use as a leave-on cosmetic cream for beautifying and enhancing the skin appearance. In addition to Dead Sea Mud said composition comprises ingredients suitable for the preparation of cosmetic cream. Said cream can further comprise up to 4 wt.% Dead Sea water. [on SciFinder(R)]
Lay summary:
The article applies theory about high-performance teams, developed in the private sector, to public sector teams tasked with implementing IT projects. The article compares two different forms of project teams: work groups committees. It proposes that work groups are more effective at ensuring project implementation. Drawing on 2 case studies the article provides general lessons on staffing, structuring and supervising public sector IT workgroups.
Publication significance:
The smooth governance of a country depends on efficient public sector IT project implementation. Yet, the public sector consistently lags behind private sector technological efficiency. The article addresses this critical challenge to public sector legitimacy. The article compares two team project models, the workgroup and the committee, and presents important findings that provide insight into the design and implementation of effective public sector team projects.
Presents an overview to articles on morphological processing published in the periodical 'Language and Cognitive Processes,' volume 15, 2000. Garnering of evidence from Hebrew, French, Italian, Spanish, Catalan, Dutch, German, Finnish, Chinese and English languages; Ecological validity of models of word recognition; Focus on cognitive processes within the visual modality.
Thermionic emission is discussed as a long time (microseconds) decay mode of energy-rich large molecules, metallic and metcar clusters, and fullerenes. We review what is known and consider the many experiments, systems, and theoretical and computational studies that still need to be done. We conclude with a wish list for future work. Particular attention is given to the experimental signatures, such as the dependence on the mode of energy acquisition, and theoretical indications of a not-quite-statistical delayed ionization and to the competition of electron emission with other decay modes, such as fragmentation or radiative cooling. Coupling of the electronic and nuclear modes can be a bottleneck and quite long time-delayed ionization can be observed, as in the decay of high Rydberg states probed by ZEKE spectroscopy, before the onset of complete energy partitioning.
Agent-based modeling is a technique used to study relationships between variation in parameter values or patterns of interaction at the micro-level and outcomes at the macro-level. By using computer simulation of landscapes inhabited by cells, or “agents,” the modeler can produce many virtual histories of the landscape under different initial conditions (randomized or not) and under various experimental conditions. In this article we report the findings of experiments run with the Agent-Based Argument Repertoire (ABAR) Model—experiments designed to help answer some of the practical questions that arise in discussions of the contribution-enhanced public discourse, that is, more and better deliberation or argumentation among citizens might contribute to the quality of democracy.
Potential energy surface points computed from variants of density functional theory (DFT) are used to calculate directly the anharmonic vibrational frequencies of H2O, Cl-H2O, and (H2O)(2). The method is an adaptation to DFT of a recent algorithm for direct calculations of anharmonic vibrational frequencies using ab initio electronic structure codes. The DFT calculations are performed using the BLYP and the B3LYP functionals and the results are compared with experiment, and also with those calculated directly from a potential energy surface obtained using ab initio Moller-Plesset second-order perturbation theory (MP2). The direct calculation of the vibrational states from the potential energy points is performed using the correlation-corrected vibrational self-consistent field (CC-VSCF) method. This method includes anharmonicity and correlations between different vibrational modes. The accuracy of this method is examined and it is shown that for the experimentally measured transitions the errors in the CC-VSCF calculations are much less than the errors due to the potential energy surface. By comparison with the experimentally measured frequencies the CC-VSCF method thus provides a test for the quality of the potential energy surfaces. The results obtained with the B3LYP functional, in contrast to those of the BLYP functional, are of comparable quality to those obtained with MP2. The B3LYP anharmonic frequencies are in good agreement with experiment, showing this DFT method describes well the anharmonic part of the potential energy surface. The BLYP results systematically underestimate both the harmonic and anharmonic frequencies and indicate that using this functional for the description of hydrogen-bonded systems may cause significant errors. (C) 2000 American Institute of Physics. [S0021-9606(00)30105-2].
The anharmonic vibrational frequencies of H2O, Cl-H2O and (H2O)(2) are calculated using potential energy surfaces computed from DFT, specifically the generalized-gradient approximation (GGA) functional HCTH and the hybrid functional B97(2c). HCTH gives reasonable agreement with experiment and can be recommended in situations where the use of a hybrid functional would be difficult. B97(2c) is found to be superior in accuracy to all other functionals tested and should be the functional of choice when the anharmonic potential energy surfaces of polyatomic systems are required for spectroscopic or similar applications. This point is illustrated by the excellent agreement with experiment obtained in calculations on formic and acetic acid using the B97(2c) functional. (C) 2000 Elsevier Science B.V. All rights reserved.
The cooperative condensation of DNA and cationic liposomes to form ordered aggregates in aqueous solution is associated with the release of partially bound counterions. We directly determine the extent of counterion release by separating the supernatant from the precipitated condensates, measuring the conductivity of the solution before and after the phase transition. The extent of counterion release is calculated for a range of lipid/DNA concentration ratios based on the nonlinear Poisson-Boltzmann theory. Both experiment and theory show maximal, essentially complete, release of counterions at the isoelectric point, where the positive (lipid)/negative (DNA) charge ratio is 1:1. Furthermore, at this point the entropic contribution to the condensation free energy is maximal and dominant.
The role of ecdysteroids in the regulation of dominance and reproduction in social Hymenoptera is little explored. In the current study we compared ecdysteroid titers in hemolymph of individual queen and worker bumble bees (Bombus terrestris) that differ in their behavior, reproductive status and social environment. Egg-laying queens that head colonies and have ovaries exhibiting all stages of follicle development, had a higher ecdysteroid titer than virgin queens whose ovaries contained only follicles at initial stages. In workers, the relationship between ecdysteroid titers and follicle development appears to be more complex and to be influenced by the bee's social status and social environment. Shortly after emergence, young workers had only follicles at the initial stages of oogenesis and they exhibited a low ecdysteroid titer. No significant, correlation was detected between ovary status and ecdysteroid titer in workers, with some workers showing activated ovaries but low ecdysteroid titers. However, at six days of age, a trend towards higher ecdysteroid titer was observed for workers in queenless groups, a condition characterized by rapid follicle development relative to queenright conditions. In these queenless groups, high social status was associated with high ecdysteroid titers. By contrast, in queenright workers ecdysteroid titers were low, even for bees with presumably high social status that had activated ovaries and were observed performing oviposition behavior. This study suggests that ecdysteroids are involved in regulation of reproduction in B. terrestris. (C) 2000 Elsevier Science Ltd. All rights reserved.
The presence of a disorganized octadecylsilane, C18, monolayer on an indium-tin oxide (ITO) electrode has a profound effect on the electrochem. of hexacyanoferrate, Fe(CN)63-/4-. The alkylsilane monolayer forms a hydrophobic matrix, which affects the heterogeneous rate of electron transfer of the metallic complex, depending on the nature of the counter cation presence in the soln. A model is suggested which accounts for these effects as well as for the changes in the formal redox potential that are obsd. [on SciFinder(R)]
Endocrine analyses were used to investigate the well-known association between queen production and the onset of worker reproduction (termed the competition phase, CPh) in Bombus terrestris. Larvae that reached the age of 5 days before the CPh had a worker-like profile: low juvenile hormone (JH) biosynthesis rates and low JH hemolymph titers. In contrast, larvae that reached the age of 5 days during the CPh had a queen-like profile: high JH biosynthesis rates and high hemolymph JH levels. Larval fate could be manipulated by transplanting egg cells into host colonies with different social structures. There was a steep rise in JH production in larvae transplanted into colonies near or during the CPh. This indicates that during colony development, larvae switch from the ``worker developmental pathway'' to the ``queen developmental pathway,'' and that the switch is socially regulated. In small rearing groups, larvae reared with queens before the CPh developed into workers, whereas those reared with queens after the CPh developed into queens. Variation in worker type (naive or experienced) did not affect caste determination. Therefore, we hypothesize that queens produce a pheromone that directly inhibits queen differentiation by larvae. We also present two alternative scenarios that explain the timing of gyne production in B. terrestris, one based on ecological constraints and the other based on queen-worker competition.
