Reliability of equivalent sphere model in blood-forming organ dose estimation

The radiation dose equivalents to blood-forming organs (BFO's) of the astronauts at the Martian surface due to major solar flare events are calculated using the detailed body geometry of Langley and Billings. The solar flare spectra of February 1956, November 1960, and August 1972 events are employed instead of the idealized Webber form. The detailed geometry results are compared with those based on the 5-cm sphere model which was used often in the past to approximate BFO dose or dose equivalent. Larger discrepancies are found for the later two events possibly due to the lower numbers of highly penetrating protons. It is concluded that the 5-cm sphere model is not suitable for quantitative use in connection with future NASA deep-space, long-duration mission shield design studies

Comparison of dose estimates using the buildup-factor method and a Baryon transport code (BRYNTRN) with Monte Carlo results

Continuing efforts toward validating the buildup factor method and the BRYNTRN code, which use the deterministic approach in solving radiation transport problems and are the candidate engineering tools in space radiation shielding analyses, are presented. A simplified theory of proton buildup factors assuming no neutron coupling is derived to verify a previously chosen form for parameterizing the dose conversion factor that includes the secondary particle buildup effect. Estimates of dose in tissue made by the two deterministic approaches and the Monte Carlo method are intercompared for cases with various thicknesses of shields and various types of proton spectra. The results are found to be in reasonable agreement but with some overestimation by the buildup factor method when the effect of neutron production in the shield is significant. Future improvement to include neutron coupling in the buildup factor theory is suggested to alleviate this shortcoming. Impressive agreement for individual components of doses, such as those from the secondaries and heavy particle recoils, are obtained between BRYNTRN and Monte Carlo results

Discrimination of the notifiable pathogen Gyrodactylus salaris from G-thymalli (Monogenea) using statistical classifiers applied to morphometric data

The identification and discrimination of 2 closely related and morphologically similar species of Gyrodactylus, G. salaris and G. thymalli, were assessed using the statistical classification methodologies Linear Discriminant Analysis (LDA) and k-Nearest Neighbours (KNN). These statistical methods were applied to morphometric measurements made on the gyrodactylid attachment hooks. The mean estimated classification percentages of correctly identifying each species were 98±1% (LDA) and 97±9% (KNN) for G. salaris and 99±9% (LDA) and 73±2% (KNN) for G. thymalli. The analysis was expanded to include another 2 closely related species and the new classification efficiencies were 94±6%(LDA) and 98±0% (KNN) for G. salaris; 98±2% (LDA) and 72±6% (KNN) for G. thymalli; 86±7% (LDA) and 91±8% (KNN) for G. derjavini ; and 76±5% (LDA) and 77±7% (KNN) for G. truttae. The higher correct classification scores of G. salaris and G. thymalli by the LDA classifier in the 2-species analysis over the 4-species analysis suggested the development of a 2-stage classifier. The mean estimated correct classification scores were 99±97% (LDA) and 99±99% (KNN) for the G. salaris±G. thymalli pairing and 99±4% (LDA) and 99±92% (KNN) for the G. derjavini±G. truttae pairing. Assessment of the 2-stage classifier using only marginal hook data was very good with classification efficiencies of 100% (LDA) and 99±6%(KNN) for the G. salaris±G. thymalli pairing and 97±2%(LDA) and 9±2%(KNN) for the G. derjavini±G. truttae pairing. Paired species were then discriminated individually in the second stage of the classifier using data from the full set of hooks. These analyses demonstrate that using the methods of LDA and KNN statistical classification, the discrimination of closely related and pathogenic species of Gyrodactylus may be achieved using data derived from light microscope studies

Improved model for solar cosmic ray exposure in manned Earth orbital flights

A calculational model is derived for use in estimating Solar cosmic ray exposure to critical body organs in low-Earth orbit at the center of a large spherical shield of fixed thickness. The effects of the Earth's geomagnetic field and the astronauts' self-shielding are evaluated explicitly. The geomagnetic field model is an approximate tilted eccentric dipole with geomagnetic storms represented as a uniform-impressed field. The storm field is related to the planetary geomagnetic index K(sub p). The code is applied to the Shuttle geometry using the Shuttle mass distribution surrounding two locations on the flight deck. The Shuttle is treated as pure aluminum and the astronaut as soft tissue. Short-term, average fluence over a single orbit is calculated as a function of the location of the lines of nodes or long-term averages over all lines of nodes for a fixed inclination

Use of Visual Aids in Teaching Shop Safety

This study was made because the writer recognized the need for the use of more visual aids in the school shop safety program. The writer mailed ninety-four questionnaire cards; fifty-two were returned. The replies on the cards indicated the lack of the use of many of the visual aids which could add much to the shop safety program. The study also includes a brief history of education and industrial arts, the development of visual aids and the description and application of various visual aids to the shop safety program. Conclusions and Hecommendations: A visually aided program is more effective than a completely verbal one. Approximately eightyfive per cent of the total knowledge gained by students is acquired through the sense of sight. The shop instructor should enrich the safety program by the use of visual aids. The media should be chosen that will most effectively meet the safety problem. The application of the visual aid must be understood. Future application toward the solution of the shop safety problems will be increased if the students help prepare or present the visual aids.Industrial Arts Educatio