A semiclassical time-dependent self-consistent-field (TDSCF) method is developed for dealing with the difficulties caused by the nonpreservation of zero-point energy in classical molecular dynamics simulation. The method is applied to a collinear model of a (Ne)12 cluster at very low temperatures. Classically, this system dissociates rapidly due to its zero-point energy. We show that the system remains stable when treated by the new method. The normal mode dynamics of the anharmonic cluster are calculated and discussed. Interesting results are obtained on the lifetimes of single-mode states and energies due to the coupling between the modes. Some of the single-mode states have subpicosecond lifetimes, while others are stable for at least 60 ps. The results illustrate the power of semiclassical TDSCF as a tool for studying the vibrational dynamics of anharmonic cluster at very low temperatures.
1993. “Varlam Shalamov's Kolyma.” In Between Heaven and Hell: The Myth of Siberia in Russian Culture, Pp. 151-69. Ed. Galya Diment and Yuri Slezkine. New York: St. Martin's Press.
The van der Waals cluster molecule ArCO2 is studied computationally by using the vibrational self-consistent field (SCF) approximation, with an approximate but reasonable potential function. Calculations are carried out both for the full six-dimensional motion and for a reduced two-dimensional problem in which the CO2 is held rigid. An interesting dynamical transition is found in the motion of the Ar atom. Its equilibrium geometry is a symmetric T-shape, and for low excitations both the radial and the angular motions in the CO2 plane resemble the states of anharmonic oscillators (smaller intervals with higher excitations). Above the sixth state of the bend in the angle theta, however, the bend spectrum changes to that of a rigid rotor, with spacings of 2Bn(theta) for quantum number n(theta). The one-dimensional effective SCF potentials along the theta coordinate and plots of the wave function both show a dynamical transition, in which, above n(theta) = 6, the motion of the Ar in the CO2 plane is essentially that of a rigid rotor in the theta coordinate. Calculations of the principal moments of inertia support this interpretation.
An accidental shooting of a woman in 1951 in the Israeli village of Tsomet has generated many stories that reflect this border community's concerns and fears. This article analyzes the relationship between the event and the community, seeking to understand the many narrative versions of the story by looking closely at the specific sociocultural context of a town settled by Tunisian Jewish immigrants. Different versions of the story reflect the nature of the immigrant experience in Tsomet and reveal local notions about proper gender relations.
A modified polymer, i.e. benzylated polyethyleneimine (PEI), coated on a glassy C electrode in which neg. charged quinones were incorporated, was used for voltammetric measurement of pH. A linear dependence of the av. of the peak potentials as a function of pH was obsd. The system was successfully applied also to ultramicroelectrodes. [on SciFinder(R)]
This paper presents an empirical assessment of the employment effects of two assistance schemes aimed at improving the accessibility of small businesses to capital. The first scheme is a revolving loan fund operating in two small towns. The second is a capital grant scheme aimed at promoting industrial activity in rural areas. Empirical data relating to the period 1986–89 is analysed for both schemes.
The employment effectiveness of the loan fund is analysed via the estimation of cost-per-job indices and the estimation of the ‘deadweight’ effect, i.e., employment that would have been created even in the absence of the financing scheme. For the grant scheme, the methodology implemented involves the use of regression techniques in order to isolate the effect of the financial assistance on employment generation. The results point to the cost-effectiveness of this form of assistance. From a public policy point of view, the need for targeting these type of schemes (both spatially and sectorally), is stressed.
An increasing body of experimental data suggests a role for 24,25(OH)2D3 in bone metabolism. The present study was carried out to assess a possible therapeutic role of this vitamin D metabolite in renal osteodystrophy. Twenty-two chronic dialysis patients, most of whom were previously maintained on 1 alpha (OH)D3 therapy, received additional treatment with 10 micrograms/day 24,25(OH)2D3 and were compared to 19 patients receiving 1 alpha (OH)D3 alone. Analysis of transiliac bone biopsies obtained at study entry and following 10-16 months of treatment revealed that the combined therapy produced a decrease in bone turnover. Specifically, the addition of 24,25(OH)2D3 inhibited an increase in trabecular bone volume (BV/TV) and suppressed osteoclastic parameters. Thus BV/TV increased from 26.2 +/- 8.6 to 32.1 +/- 7.5% (p < 0.01) in the 1 alpha (OH)D3 group, but it remained unchanged in the combined therapy group. In contrast, the eroded surface (ES/BS), the osteoclast surface (Oc.S/BS), and the osteoclast numbers were significantly suppressed in patients receiving both 24,25(OH)2D3 and 1 alpha (OH)D3, as compared with those receiving 1 alpha (OH)D3 alone (p < 0.01, p < 0.01, and p < 0.001, respectively). These improvements were independent of changes in 1 alpha (OH)D3 dosage. The extent of bone aluminium deposits was unrelated to the administration of 24,25(OH)2D3 or to its effect. 24,25(OH)2D3 therapy was not associated with any adverse effects.
Molecular beam scattering experiments have emerged in recent years as an important tool for investigating structural disorder on surfaces. This paper gives a brief overview of the developing theory of scattering from disordered surfaces, which is essential for the interpretation of such experiments, and presents new results on this topic. A brief discussion is given of the methods developed for calculating atom scattering from disordered. systems (e.g. time-dependent quantum wavepackets; distorted-wave approximation; sudden approximation) and of simulations of disordered surface structures (by Monte Carlo or molecular dynamics). The paper focuses, however, on features of the scattering intensities and their relation to disordered surface structures. The main topics include: (1) The concept of cross section for He scattering by an isolated defect on a surface, and its application to the study of interactions between defects. Comsa and his coworkers developed this into a most powerful tool for studying surface defects and defect interactions. We examine the assumptions involved, and the information contained in the measured cross section on defect shape and geometry, and on He/defect potentials. (2) Angular intensity distribution for He scattering from isolated defects; defect rainbow and Fraunhofer effects. (3) He scattering from periodic, substitutionally disordered surfaces. New results are presented on He scattering from mixed Xe + Kr monolayers on Pt(111), comparing theory with the experiments of Comsa et al. The results indicate that these monolayers are indeed periodic and (almost) perfectly substitutionally disordered for all Xe:Kr ratios. Rainbow intensity features due to the substitutional disorder are calculated and analyzed. (4) He scattering from amorphous mixed monolayers, with application to Xe + Ar mixtures on Pt (111). (5) Atom scattering from liquid surfaces, e.g. structure and dynamics of liquid Hg probed by Ar scattering. The paper concludes by emphasizing some of the outstanding open problems in the field.
Reprinted in John France (Ed.), Medieval Warfare 1000-1300, Aldershot: Ashgate, 2006.
Ariel Shisha-Halevy. 1992. “Bohairic.” In The Coptic Encyclopaedia, 8: Pp. 54–60. Abstract
A major dialect of Coptic, called “Memphitic”, ‘the northern dialect”, or “dialect of Lower Egypt” in earlier terminology, or simply “Coptic” in eighteenth- and nineteenth-century treatises, Bohairic being the first Coptic dialect with which Western scholarship became aquainted. “Bohairic” (B) was first used by Stern (1880, p. xii).
Bruce Glymour, Rick Grush, Valerie Gray Hardcastle, Brian Keeley, Joe Ramsey, Oron Shagrir, and Ellen Watson. 1992. “The Cartesian Theater Stance.” Behavioral and Brain Science, 15, Pp. 209-210.
We offer a definition of coalition-proof communication equilibria. The use of games of incomplete information is essential to our approach. Deviations of coalition are introduced after their players are informed of the actions they should follow. therefore, improvements by coalition on a given correlated strategy should always be made when their players have private information. Coalition-proof communication equilibria of two-person games are characterized by "information efficiency". Several examples are analyzed, including the Voting Paradox.
