High finesse ring resonators made by silver ion exchange in glass

We report the fabrication of single tap ring resonators made by thermal silver ion-exchange in various types of glass substrates. The highest finesse achieved was 55 with an efficiency of 32 percent. We systematically measured losses arising from different sources such as intrinsic absorption in the glass and scattering from side wall roughness arising from the mask fabrication technique. All data was measured atlambda = 0.6328 mum.     

Conversion of ionization measurements to radiation absorbed dose in non-water density material

The radiation absorbed dose to non-water equivalent materials of interest in radiotherapy is the dose to lung and the dose to bone. The measurement and calculation of dose to the lung has been of great interest and much effort has gone into the development of accurate lung dose calculation methods. The radiation absorbed dose to the bone is usually not calculated and most absorbed dose calculations have been done without correcting for the presence of bone. For the lower megavoltage photon beams this may be appropriate, however, as the energy of the photon beam increases, the region of electronic disequilibrium becomes larger and pair production which depends on the atomic number of the material becomes significant. Therefore the bone will produce greater perturbations of the dose distribution. The dose to lung-equivalent material is uniquely obtained from ionization measurements. However, in bone-equivalent materials two different calculations of absorbed dose are possible: the absorbed dose to soft tissue plastic (polystyrene) within bone-equivalent material and the dose to the bone-equivalent material itself. Both can be calculated from ionization measurements in phantoms. These two calculations result in significantly different doses in a heterogeneous phantom composed of polystyrene and aluminium (a bone substitute). The dose to a thin slab of polystyrene in aluminium is much higher than the dose to the aluminium itself at the same depth in the aluminium. Monte Carlo calculations confirm that the calculation of dose to polystyrene in aluminium can be accurately carried out using existing dosimetry protocols. However, the conversion of ionization measurements to absorbed dose to high atomic number materials cannot be accurately carried out with existing protocols and appropriate conversion factors need to be determined.     

Psychology and the resurgent space program.

Reviews some of the psychological aspects of the space missions that began with the launching of the space shuttle Columbia in 1981. Among the salient issues discussed are those involving biobehavioral response, human factors, communications, and personal and social adjustment in space. It is argued that psychologists should be concerned with the human aspects of spaceflight. Weightlessness, confinement, high risk, and other spaceflight conditions provide special opportunities for testing theories from virtually all areas of psychology including physiological, perception, cognitive, learning, personality, social, and organizational psychology. It is concluded that as the profession of psychology gains greater understanding of the psychological issues of adaptation to outer space and builds credibility with mission personnel, psychologists will discover new research challenges and will play an increasingly important role in mission planning and in flight operations. (69 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Establishing the relationship between urban land-cover configuration and night time land-surface temperature using spatial regression

Studies suggest that urban form can influence microclimate regulation. Remote sensing studies have contributed to these findings through analysis of high-resolution land cover maps, landscape ecology metrics, and thermal imagery. Collectively, these have been referred to as land cover configuration studies. There are three objectives to this study. The first is to assess the relationship between nighttime land surface temperatures (LST) and land cover configuration and composition. The second objective is to outline a comprehensive methodology that includes ordinary least squares (OLS), spatial regression, variable selection, and multicollinearity analysis. Our last objective is to test three hypotheses about the relationship between LST and land cover, which can briefly be described as: 1) the importance of land-use regimes in modeling LST from land cover composition and configuration variables; 2) the strength of the correlation between LST and roads, buildings, and vegetation; and 3) the improved quality of models using landscape metrics in modeling the relationship between LST and land cover. Based on 16 different models (8 OLS, 8 spatial regression) we could confirm the above hypotheses, but we found that the configuration of buildings, roads, and vegetation have a complex relationship with LST. Our interpretation of this complexity, combined with the strength of composition variables, is that parsimonious models, for now, are more useful to urban planners because they are more generalizable. Finally, spatial regression models of land cover configuration and LST demonstrated an improvement over non-spatial linear models (OLS). Spatial regression models reduced heteroskedasticity and clusters of residuals, and tempered coefficients, suggesting that the OLS models could be biased. OLS models were still found to be a valuable tool for exploratory analysis.     

An Analysis of the Effect of Lubricant Supply Rate on the Performance of the 360° Journal Bearing

A theoretical study was made to determine the influence of lubricant supply rate on the performance of the 360° journal bearing for L/D = 1. The results are presented in chart form to facilitate their application to analysis and design.     

Theory and Experiment with a Gas Stabilized Constricted Arc

Measurements of voltage gradient and static pressure distribution in the constrictor of a gas stabilized constricted arc discharge are reported. These and previously obtained data yielding the column diameter are used to compare the behavior of this discharge with laminar column theories. Significant disagreement are found, and it is concluded that the discharge represents an inlet flow region. A qualitative model is presented of the physical processes occuring in this inlet region. The implications for arc heater efficiency of this model and of the data are discussed.     

Male and female alcoholics'' attributions regarding the onset and termination of relapses and the maintenance of abstinence

The application of a knowledge-based segmentation method to the problem of automatically detecting the outer follicle wall boundary in ultrasonographic images of ovaries is presented. A combination of computer detection and interactive adjustment was used to define an approximate inner follicle-wall boundary, which was then used by the computer algorithm as a priori knowledge to automatically find the outer follicle-wall border. The segmentation algorithm was tested on ultrasonographic images of women's ovaries that were imaged in vivo. The semiautomatic segmentations were compared to segmentations by an expert human observer in terms of border placement differences and in terms of quantitative parameters relevant to the physiologic status of the follicles. These physiological parameters include total and specific signal intensity from the follicle and from the follicle wall. The computer-detected outer follicle wall boundaries correlated well with the human observer-defined wall boundaries, in terms of enclosed follicle area, specific and total follicle signal, enclosed wall area, and specific and total wall signal. The actual border placement differences were also small, with a maximum placement difference of 1.47 +/- 0.83 mm and a root mean square (r.m.s.) placement difference of 0.59 +/- 0.28 mm.