Energy Transfer in Molecular Collisions

Computational studies of energy transfer in models of molecular collisions are presented and analyzed qualitatively and semi-quantitatively. Particular attention is given to those approximations where the leading term is already in good qualitative agreement with the exact numerical results. In particular, results for the distorted wave approximation in an adiabatic basis are reported and compared with the exact results. It is argued that for slow molecular collisions, the efficiency of the transfer is determined by the “Franck Condon” overlap near the repulsive part of the intermolecular potential.     

The aging behavior of orthorhombic marten site in Ti-6-2-4-6

In Ti-6-2-4-6 alloys, beta transforms to orthorhombic martensite when quenched from a temperature of 1188 or above, X-ray analysis showed that aging at 773 or 873 gradually reduces the degree of orthorhombicity until a hexagonal structure equivalent to alpha, but having the morphological characteristics of the prior martensite, is produced. The orthorhombicity is reduced by solute rejection to beta which forms as particles both homogeneously and heterogeneously within the martensitic structure. The structure at maximum hardness is a fine distribution of Burger’s oriented beta particles in a matrix of martensite of greatly reduced orthorhombicity. Overaging appears to occur as a result of coarsening of the homogeneous beta particles. It is shown that aging at temperatures from 873 to 1083 K results in growth of one particular varient of the beta which is located at the interface between twin related regions composing a martensite lath. This beta along with similarly oriented beta at lath interfaces forms a continuous beta matrix by a gradual growth process. It is shown that this matrix has the identical orientation and shape of the original beta grain prior to quenching. A mechanism is proposed to account for this “memory effect”.     

Response of graywater recycling systems based on hydroponic plant growth to three classes of surfactants

Anionic (sodium laureth sulfate, SLES), amphoteric (cocamidopropyl betaine, CAPB) and nonionic (alcohol polyethoxylate, AE) surfactants were added to separate nutrient film technique (NFT) hydroponic systems containing dwarf wheat (Triticum aestivum cv. USU Apogee) in a series of 21 day trials. Surfactant was added either in a (1). temporally dynamic mode (1-3 g surfactant m(-2) growing area d(-1)) as effected by automatic addition of a 300 ppm surfactant solution to meet plant water demand, or (2). continuous mode (2 g surfactant m(-2) growing area d(-1)) as effected by slow addition (10 mLh(-1)) of a 2000 ppm surfactant solution beginning at 4d after planting. SLES showed rapid primary degradation in both experiments, with no accumulation 24 h after initial addition. CAPB and AE were degraded less rapidly, with 30-50% remaining 24 h after initial addition, but CAPB and AE levels were below detection limit for the remainder of the study. No reductions in vegetative growth of wheat were observed in response to SLES, but biomass was reduced 20-25% with CAPB and AE. Microbial communities associated with both the plant roots and wetted hardware surfaces actively degraded the surfactants, as determined by monitoring surfactant levels following pulse additions at day 20 (with plants) and day 21 (after plant removal). In order to test whether the biofilm communities could ameliorate phytotoxicity by providing a microbial community acclimated for CAPB and AE decay, the continuous exposure systems were planted with wheat seeds after crop removal at day 21. Acclimation resulted in faster primary degradation (>90% within 24h) and reduced phytotoxicity. Overall, the studies indicate that relatively small areas (3-5m(2)) of hydroponic plant systems can process per capita production of mixed surfactants (5-10 g x person(-1)d(-1)) with minimal effects on plant growth.     

The feasibility of producing laser plasmas via photoionization

The production of uniform large-volume laser plasmas with electron-ion densities on the order of 10¹²/cm³or larger by means of photoionization is investigated. An externally applied electric field heats the electron gas to the optimal temperature for excitation of laser levels. Photoionization by intense UV light may take place in a low partial pressure gas of low ionization potential species dispersed throughout the host laser medium, or the laser medium itself may serve as the photoionized species. Both single-photon ionization and two-photon two-step ionization are shown to be applicable.     

Telemetered heart rate and skin potential of a chronic schizophrenic patient especially during periods of hallucinations and periods of talking.

Took telemetric recordings of a male 23-yr-old chronic schizophrenic patient's heart rate and skin potential while on the ward. During periods of hallucinations, the skin potential increased significantly, while there were no changes in heart rate. Neither heart rate nor skin potential increased during periods of talking. When very angry, heart rate showed a substantial deceleration followed by a large increase. There was no change in skin potential during the period of anger. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predictability, control, and the pituitary-adrenal response in rats.

Compared the effects of signaled and unsignaled shock on the pituitary-adrenal response of 68 male Long-Evans hooded rats. In Exp I, exposure to the 2 procedures yielded no difference in plasma corticosterone levels. In Exp II, the addition of a food-reinforced leverpressing baseline produced conditioned suppression in the signaled condition but no group difference in steroid values. To guard against steroid elevations produced by exposure to shock, blood samples in Exp III were obtained during brief test sessions prior to the occurrence of shock. The procedure resulted in a significant elevation in the steroid levels of the signaled shock group. In Exp IV, a within-Ss sampling procedure revealed that disparate group steroid values obtained earlier in the session had converged by the end of the test session. The final experiment produced the original failure to obtain a steroid difference due to predictability in the absence of a behavioral baseline. Results suggest that (a) the effects of predictability are largely seen in the temporal pattern of steroid elevations and not in their terminal values, (b) the effects of predictability on steroids are modulated by the availability of control, and (c) control is not confined to the stimulus that is being predicted. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonlinear optical susceptibility of the thiogallate CdGa2S4

The nonlinear optical coefficient d36of CdGa2S4was measured to be 5 times larger than d31(LiNbO3). This large non-linearity is in good agreement with theory.     

Emerging Cooperation With Minimal Effort: Rewarding Over Mimicking

This paper compares supervised and unsupervised learning mechanisms for the emergence of cooperative multiagent spatial coordination using a top-down approach. By observing the global performance of a group of homogeneous agents-supported by a nonglobal knowledge of their environment-we attempt to extract information about the minimum size of the agent neurocontroller and the type of learning mechanism that collectively generate high-performing and robust behaviors with minimal computational effort. Consequently, a methodology for obtaining controllers of minimal size is introduced and a comparative study between supervised and unsupervised learning mechanisms for the generation of successful collective behaviors is presented. We have developed a prototype simulated world for our studies. This case study is primarily a computer games inspired world but its main features are also biologically plausible. The two specific tasks that the agents are tested in are the competing strategies of obstacle-avoidance and target-achievement. We demonstrate that cooperative behavior among agents, which is supported only by limited communication, appears to be necessary for the problem's efficient solution and that learning by rewarding the behavior of agent groups constitutes a more efficient and computationally preferred generic approach than supervised learning approaches in such complex multiagent worlds     

Concurrent brief versus intensive smoking intervention during alcohol dependence treatment.

Alcohol dependent smokers (N=118) enrolled in an intensive outpatient substance abuse treatment program were randomized to a concurrent brief or intensive smoking cessation intervention. Brief treatment consisted of a 15-min counseling session with 5 min of follow-up. Intensive intervention consisted of three 1-hr counseling sessions plus 8 weeks of nicotine patch therapy. The cigarette abstinence rate, verified by breath carbon monoxide, was significantly higher for the intensive treatment group (27.5%) versus the rate for the brief treatment group (6.6%) at 1 month after the quit date but not at 6 months, when abstinence rates fell to 9.1% for the intensive treatment group and 2.1% for the brief treatment group. Smoking treatment assignment did not significantly impact alcohol outcomes. Although intensive smoking treatment was associated with higher rates of short-term tobacco abstinence, other, perhaps more intensive, smoking interventions are needed to produce lasting smoking cessation in alcohol dependent smokers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)