Life testing of metal-ceramic CO2 lasers

The main purpose of this program was to determine the life characteristics of nine space-qualified, metal-ceramic CO2 lasers. Lifetimes ranged between about 400 hours to over 2000 hours (the limit of testing) with a high degree of consistency in like groups. In all cases the tubes which had failed could be restored to near their original power by doubling the cathode current for 30 minutes. Periodic rejuvenation allowed operation for the full 2000 hours on all tubes. The failure mechanism appears to involve formation of NiO and C on the nickel cathode emission surface with subsequent absorption of tube gases

Hydrologic and Water Quality Monitoring on Turkey Creek Watershed, Francis Marion National Forest, SC

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

Vibration suppression in cutting tools using collocated piezoelectric sensors/actuators with an adaptive control algorithm

The machining process is very important in many engineering applications. In high precision machining, surface finish is strongly correlated with vibrations and the dynamic interactions between the part and the cutting tool. Parameters affecting these vibrations and dynamic interactions, such as spindle speed, cut depth, feed rate, and the part's material properties can vary in real-time, resulting in unexpected or undesirable effects on the surface finish of the machining product. The focus of this research is the development of an improved machining process through the use of active vibration damping. The tool holder employs a high bandwidth piezoelectric actuator with an adaptive positive position feedback control algorithm for vibration and chatter suppression. In addition, instead of using external sensors, the proposed approach investigates the use of a collocated piezoelectric sensor for measuring the dynamic responses from machining processes. The performance of this method is evaluated by comparing the surface finishes obtained with active vibration control versus baseline uncontrolled cuts. Considerable improvement in surface finish (up to 50%) was observed for applications in modern day machining

Selling lottery products to minors: factors affecting retailer compliance

Illegal gambling by adolescent minors has become a major issue in many societies and lottery gambling is often considered a "gateway" to gambling more generally among this age group. The purpose of this study was to identify the influencing factors that affect retailer compliance concerning the selling of lottery products to minors. The research team received the original data (i) directly from the sales agents of the Austrian Lotteries after their responsible gambling training of the retailer in 2014/2015 (Round 1: n = 5032), (ii) directly from a third-party agency carrying out test purchases (i.e., "mystery shopping") in 2014 (Round 2: n = 1421), and (iii) retailers’ responses to their attitudes to youth protection issues (through direct interface with the research team) in 2015 (Round 3: n = 4516). The data from a total of 1036 participants who had taken part in all three rounds was analyzed in the present study. Results showed that in 13.1% of mystery shopping checks (n = 1421), lottery products were sold to a test purchaser under the age of 16 years. The analysis also showed that the older the test purchaser, the greater the likelihood that a lottery product was sold. Under-age lottery sales to girls were over three times more prevalent than sales to boys. Finally, the analysis showed that the higher the number of responsible gambling training sessions completed in the past and the more positive the attitude towards mystery shopping, the higher the compliance rate not to sell a lottery product to young mystery shoppers. Recommendations to increase compliance and raise the awareness among retailers are presented

Sex differences in the immune system become evident in the perinatal period in the four core genotypes mouse

We have used the four core genotypes (FCG) mouse model, which allows a distinction between effects of gonadal secretions and chromosomal complement, to determine when sex differences in the immune system first appear and what influences their development. Using splenic T cell number as a measure that could be applied to neonates with as yet immature immune responses, we found no differences among the four genotypes at postnatal day 1, but by day 7, clear sex differences were observed. These sex differences were unexpectedly independent of chromosomal complement and similar in degree to gonadectomized FCG adults: both neonatal and gonadectomized adult females (XX and XY) showed 2-fold the number of CD4+ and 7-fold the number of CD8+ T cells versus their male (XX and XY) counterparts. Appearance of this long-lived sex difference between days 1 and 7 suggested a role for the male-specific perinatal surge of testicular testosterone. Interference with the testosterone surge significantly de-masculinized the male CD4+, but not CD8+ splenic profile. Treatment of neonates demonstrated elevated testosterone limited mature cell egress from the thymus, whereas estradiol reduced splenic T cell seeding in females. Neonatal male splenic epithelium/stroma expressed aromatase mRNA, suggesting capacity for splenic conversion of perinatal testosterone into estradiol in males, which, similar to administration of estradiol in females, would result in reduced splenic T cell seeding. These sex steroid effects affected both CD4+ and CD8+ cells and yet interference with the testosterone surge only significantly de-masculinized the splenic content of CD4+ cells. For CD8+ cells, male cells in the thymus were also found to express one third the density of sphingosine-1-phosphate thymic egress receptors per cell compared to female, a male characteristic most likely an indirect result of Sry expression. Interestingly, the data also support a previously unrecognized role for non-gonadal estradiol in the promotion of intra-thymic cell proliferation in neonates of both sexes. Microarray analysis suggested the thymic epithelium/stroma as the source of this hormone. We conclude that some immune sex differences appear long before puberty and more than one mechanism contributes to differential numbers and distribution of T cells