Impulse approximation in solid helium

The incoherent dynamic form factorS _i(Q, ) is evaluated in solid helium for comparison with the impulse approximation (IA). The purpose is to determine theQ values for which the IA is valid for systems such as helium where the atoms interact via a potential having a steeply repulsive but not infinite hard core. For³He,S _i(Q, ) is evaluated from first principles, beginning with the pair potential. The density of statesg() is evaluated using the self-consistent phonon theory andS _i(Q, ) is expressed in terms ofg(). For solid⁴He reasonable models ofg() using observed input parameters are used to evaluateS _i(Q, ). In both casesS _i(Q, ) is found to approach the impulse approximationS _IA(Q, ) closely for wave vector transfersQ20 Å^–1. The difference betweenS _i andS _IA, which is due to final state interactions of the scattering atom with the remainder of the atoms in the solid, is also predominantly antisymmetric in (–_R), where _R is the recoil frequency. This suggests that the symmetrization procedure proposed by Sears to eliminate final state contributions should work well in solid helium.     

Observations of shadow bands at the total solar eclipse of 16 February 1980

Photoelectric observations of short term light variations (shadow bands) at the 16 Feb. 1980 total solar eclipse have been made using a set of spatially separated PIN diodes. Light variations in a bandpass of 1-500 Hz were detected during the half-minutes preceding and following the total phase. Fourier analysis of the noise spectrum of the variations reveals a sharp drop-off for frequencies above 50 Hz and an overall spectrum quite similar to previously reported power spectra of stellar scintillation. This is consistent with an atmospheric origin for the shadow bands. Cross-correlations between the detector outputs are low, suggesting a short persistence time for the turbulent elements causing the patterns.     

Chemical vapour deposition of chromium onto nickel

The chemical vapour deposition (CVD) of chromium onto a pure nickel substrate was investigated in the presence of hydrogen at three temperatures (950, 1000 and 1050°C) using a pack cementation method.Of the thermochemical reactions generally involved in CVD, such as thermal decomposition, reduction, displacement and disproportionation, the only significant reaction which occurs for this system is a reduction of CrCl₂ by hydrogen according to

$\text{CrCl}{}_2\text{(g)+H}{}_2\text{(g)→Cr(s)+2HCl(g)}$

Two diffusion layers appear during the process. (1) In the early stages of deposition a nickel-rich layer with a face-centred cubic structure develops. (2) Depending on the time and the temperature of the coating, an outer chromium-rich layer with a body-centred cubic structure develops progressively on the sample surface and grows from or together with the inner layer.The deposition rate is controlled by diffusion of the chromium and the nickel atoms through the coating layers, mainly through the inner layer.     

Drawing of optical fiber with internal codrawn wire and conductive coating and electrooptic modulation demonstration

One hundred twenty meters of fiber with an internal codrawn wire and electrically conductive coating was successfully fabricated for the first time. The integration of the conductive coating and wire was all performed during the fiber draw stage, in a process that enabled arbitrarily long lengths of fiber to be made. The wire combined with the conductive coating enables a strong electric field to be formed across the optical core. Such a fiber is ideal for thermally poling long lengths and for nonlinear device applications such as optical switches and modulators.     

Microstructure evolution of the Sn–Ag–y%Cu interconnect

The lead free Sn–Ag–y%Cu (y = 0.0, 0.5, 1.0 and 2.0) interconnect interfacial microstructures and the microstructure evolution under thermal treatment (isothermal aging, 150 °C/1000 h) were studied in detail by using surface microetching microscopy and cross section microscopy. The corresponding mechanical and reliability behaviors were evaluated by performing shear test and fracture mode analysis before and after the thermal treatment. The results indicate: (i) The interconnects could have different microstructures and intermetallic compound (IMC), depending on the Cu content. The Cu–Sn IMC could have microstructures that were clusters or protrusion-like, Augustine grass leaf-like, scissor-like, tweezers-like, etc. (ii) Ag₃Sn IMCs were not observed at time zero for any interconnect groups, but they occurred after the aging for all groups. The Ag₃Sn IMC could have different microstructures, again depending on Cu content. For low Cu content, the Ag₃Sn IMCs were granules or nodules; for higher Cu content, Ag₃Sn IMCs were plate-like. (iii) The growth of Ag₃Sn plates was promoted by the growth of Cu–Sn IMCs, but indirectly linked to the Cu content. (iv) High Cu content (1.0 wt% and higher) could degrade the mechanical and reliability performances of the LF interconnect by providing a brittle joint, which was mainly achieved through the substantial growth of Cu–Sn IMCs and Ag₃Sn plates.     

Damping Effect on Waves Propagating Past a Submerged Horizontal Plate and a Vertical Porous Wall

A set of analytical solutions for waves propagating past a combined submerged horizontal plate and vertical porous wall breakwater system is presented. The wave damping effect caused by the horizontal plate induced flow constriction is considered in the analysis. The velocity potentials in each fluid domain are derived based on the linear wave theory and the unknown coefficients are determined from the matching conditions using three sets of orthogonal eigenfunctions. Reflection and transmission coefficients are presented to evaluate the performance of the breakwater system. The analytical solutions in terms of the reflection and transmission coefficients as well as the hydrodynamic force on the vertical porous wall are found in good agreement with published laboratory measurements. In comparison with the solutions without taking into account the wave damping effect, the present analytical solutions significantly improve the accuracy of the wave predictions, especially for the reflected waves.     

Physical Properties of Vegetable Oil and Chlorinated Ethene Mixtures

Laboratory experiments were conducted to investigate the abiotic interactions of soybean oil (SoyOil) and chlorinated ethene (CE) nonaqueous phase liquids (NAPLs). The mixed NAPL density and interfacial tension behaved ideally, as predicted by the volume ratio. The mixed NAPL viscosity increased exponentially from that of the pure CE to that of pure SoyOil as the volume fraction increased. The measured contact angle was highly variable and was unpredictable as a function of the volume composition of the mixed NAPL. The physical property effects indicate that the mobilization of residual CE NAPLs because of SoyOil injection is unlikely. Equilibrium dissolution of CEs from the NAPL mixtures behaved linearly as a function of the mole fraction. Dissolved SoyOil in simulated groundwater enhanced the dissolution of trichloroethene (TCE) during flow tests, increasing the effluent TCE concentration from 141?to?202?mg/L. The ready intermingling of the CE dense nonaqueous phase liquids (DNAPLs) and SoyOil indicate that such interactions may be significant at sites where vegetable oil is injected into DNAPL source areas to enhance in situ anaerobic bioremediation.     

The Therapeutic Process As a Predictor of Change in Patients' Important Relationships During Time-Limited Dynamic Psychotherapy.

Components of the therapeutic process have been shown to be moderately strong predictors of change in patients' global interpersonal functioning during therapy. The authors sought to extend this research by examining how the therapeutic process in time-limited dynamic psychotherapy related to change in patients' perceptions of a specific relationship as rated by the Structural Analysis of Social Behavior. Results showed that ratings of therapist warmth at Session 3 predicted increased warmth and decreased hostility in patient behavior at posttreatment. Therapist warmth at Session 16 was predictive of a decrease in submissive behavior by patients toward their significant other. The importance of the association between the therapeutic process and patients' important interpersonal relationships is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)