Comparison of CuCl, CuBr, and CuI as lasants for copper-vapor lasers

CuCl, CuBr, and CuI have been compared in a fixed parameter system as lasants for copper-vapor lasers. The output powers for optimum temperature, buffer gas pressure, and delay time were found to be in the ratio PCuBr:PCuCl:PCuI= 6 : 3 : 2.     

Efficient mode transformations of degenerate Laguerre-Gaussian beams

We present an approach for efficient conversion of a single-high-order-mode distribution from a laser to a nearly Gaussian distribution and vice versa. It is based on dividing the high-order mode distribution into equal parts that are then combined together coherently. We implement our approach with several optical arrangements that include a combination of discrete elements and some with single interferometric elements. These arrangements are analyzed and experimentally evaluated for converting the TEM01 mode distribution with Mx(2) = 3 to a nearly Gaussian beam with Mx(2) = 1.045 or Mx(2) = 1.15. The basic principle, design, and experimental results obtained with several conversion arrangements are presented. The results reveal that conversion efficiency is typically greater than 90%, compared with theoretical ones. In addition, some arrangement is exploited for converting the fundamental Gaussian-beam distribution into the TEM01 mode distribution.     

斯坦哈特自然历史博物馆

正新的博物馆将成为特拉维大学自然历史类收藏品的新家,该建筑设计包含展览和研究两种功能。通常未展出的收藏品都会放置在一个大木箱里——珍贵的植物和动物标本储存箱。设计师正是借鉴了标本箱这一形象,将建筑体打造成一个神秘的宝箱,邀请人们进入参观。盒子式建筑体象征着永恒,兼具历史与未来两种象征意义。     

Evaluation of the resistance of mortars coated with silver bearing zeolite to bacterial-induced corrosion

An evaluation of the resistance of mortar specimens coated with silver bearing zeolite to biologically produced sulphate and their antimicrobial characteristics was carried out in this study using Acidothiobacillus thiooxidans. The evaluation was performed based on leaching Ca²⁺ and Si⁴⁺ from the cementitious matrix, rate of bacterial sulphur oxidation, increase in biomass concentration, and acid production. The cumulative concentration of Ca²⁺ leaching were 3.5-folds higher (28.5 mg Ca²⁺/g cement) and 2-folds higher (18 mg Ca²⁺/g cement) in the uncoated and epoxy coated mortar specimens compared to those of zeolite coated specimens (9 mg Ca²⁺/g cement and 8 mg Ca²⁺/g cement for type AC and AK respectively). The cumulative leaching Si⁴⁺ was also 2.6-folds higher in the control mortar specimens (0.65-1.8 mg Si⁴⁺/g cement). Biomass concentration in the control specimens reached 210 mg TSS/L, and that of the zeolites coated mortar specimens was 103 mg TSS/L. The bacterial sulphur oxidation was found to follow the same pattern of the bacterial concentration, 230-270 mg SO₄/g S and 158-182 mg SO₄/g S in the control and zeolite coated mortar specimens, respectively. The resistance of the zeolitic coating was further evidenced by the increase in pH of the control mortar specimens which demonstrated the leaching of Ca (OH)₂ from the cement matrix. The stability of zeolite coated specimens was confirmed by the absence of corrosion products as was examined by FE-SEM and XRPD.     

Analysis of natural frequencies of cavities and scatterers using animpulsive current model

A recently suggested (see Y. Leviatan et al., ibid., vol.36, p.1722-1734, Dec. 1988) method of moments solution to generalized formulations of electromagnetic scattering from perfectly conducting and material bodies of smooth shape is used to compute the natural frequencies of such bodies. The field inside the body and the field scattered from the body are expanded by means of the field of impulsive current sources (elemental dipoles) situated a distance away from (rather than on) the boundary. The key feature of this approach is the fields anywhere in space can be evaluated analytically, yielding a substantial saving of computation time in comparison with standard on-surface formulations. Impulsive expansion functions are used for the fictitious currents that simulate the source-free fields in the relevant regions, and a point matching procedure is adopted for the enforcement of the boundary conditions. The result is a generalized impedance matrix whose singularities in the complex frequency plane represent the natural frequencies of the body. The numerical solution is simple to execute, computationally efficient, and can be applied to a broad class of bodies of smooth shape. Results demonstrating the excellent accuracy of the procedure are given     

In their own words: battered women''s assessment of the criminal processing system''s responses

This study shows that relative to younger adults, older adults are more adversely influenced by similar items when judging a memory's source, and the phenomenal features of their correctly and incorrectly attributed memories have greater overlap. The authors argue in accordance with the source monitoring framework that this age-related impairment in source accuracy is related to processes involved in binding features into complex memories and those involved in accessing and evaluating contextual features of memories. These processes are linked to medial temporal and frontal brain regions, respectively, as evidenced by correlations in older adults between source accuracy and neuropsychological tests often used to assess medial temporal and frontal function. The results suggest that adequate feature binding is particularly important when items from different source share similar features and access-evaluation processes are particularly important after a delay.     

ASSØCA: FORTRAN IV program for Williams and Lambert Association analysis with printed dendrograms

A general-purpose computer program implementing Williams and Lambert's method of association analysis is documented. The method embodies a hierarchical-divisive-monothetic strategy for the numerical classification of multiattribute, binary-coded data sets. The main user-controlled options permit a selection from among two different association coefficients and three termination criteria; employment of Yates' correction; presetting significance thresholds; discarding insignificant association coefficients; treatment of ambiguities in dividing attributes; and the transformation of quantitative measurements to a binary-coded form. A line-printer dendrogram plot displaying the final classification is generated as part of the output. Both normal and inverse association analysis can be performed.     

Wide-angle chromatic aberration corrector for the human eye

The human eye is affected by large chromatic aberration. This may limit vision and makes it difficult to see fine retinal details in ophthalmoscopy. We designed and built a two-triplet system for correcting the average longitudinal chromatic aberration of the eye while keeping a reasonably wide field of view. Measurements in real eyes were conducted to examine the level and optical quality of the correction. We also performed some tests to evaluate the effect of the corrector on visual performance.     

Investigation of the cross-ratios method for point-of-gaze estimation

The cross-ratios method for point-of-gaze (PoG) estimation uses the invariance property of cross-ratios in projective transformations. The inherent causes of the subject-dependent PoG estimation bias exhibited by this method have not been well characterized in the literature. Using a model of the eye and the components of a system (camera, light sources) that estimates PoG, a theoretical framework for the cross-ratios method is developed. The analysis of the cross-ratios method within this framework shows that the subject-dependent estimation bias is caused mainly by: 1) the angular deviation of the visual axis from the optic axis and 2) the fact that the virtual image of the pupil center is not coplanar with the virtual images of the light sources that illuminate the eye (corneal reflections). The theoretical framework provides a closed-form analytical expression that predicts the estimation bias as a function of subject-specific eye parameters. The theoretical framework also provides a clear physical interpretation for an existing empirically derived two-step procedure that compensates for the estimation bias and shows that the first step of this procedure is equivalent to moving the corneal reflections to a new plane that minimizes the distance from this plane to the virtual image of the pupil center.      

The influence of positive affect on the components of expectancy motivation.

The influence of positive affect on expectancy motivation was investigated in 2 studies. The results of Study 1 indicated that positive affect improved people's performance and affected their perceptions of expectancy and valence. In Study 1, in which outcomes depended on chance, positive affect did not influence people's perceptions of instrumentality. In Study 2, in which the link between performance and outcomes was specified, positive affect influenced all 3 components of expectancy motivation. Together, the results of Studies 1 and 2 indicated that positive affect interacts with task conditions in influencing motivation and that its influence on motivation occurs not through general effects, such as response bias or general activation, but rather through its influence on the cognitive processes involved in motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)