Radionuclide measurements by accelerator mass spectrometry at Arizona

Over the past years, Tandem Accelerator Mass Spectrometry (TAMS) has become established as an important method for radionuclide analysis. In the Arizona system the accelerator is operated at a thermal voltage of 1.8MV for C-14 analysis, and 1.6 to 2MV for Be-10. Samples are inserted into a cesium sputter ion source in solid form. Negative ions sputtered from the target are accelerated to about 25kV, and the injection magnet selects ions of a particular mass. Ions of the 3+ charge state, having an energy of about 9MeV are selected by an electrostatic deflector, surviving ions pass through two magnets, where only ions of the desired mass-energy product are selected. The final detector is a combination ionization chamber to measure energy loss (and hence, Z), and a silicon surface-barrier detector which measures residual energy. After counting the trace iosotope for a fixed time, the injected ions are switched to the major isotope used for normalization. These ions are deflected into a Faraday cup after the first high-energy magnet. Repeated measurements of the isotope ratio of both sample and standards results in a measurement of the concentration of the radionuclide. Recent improvements in sample preparation for C-14 make preparation of high-beam current graphite targets directly from CO2 feasible. Except for some measurements of standards and backgrounds for Be-10 measurements to date have been on C-14. Although most results have been in archaeology and quaternary geology, studies have been expanded to include cosmogenic C-14 in meteorites. The data obtained so far tend to confirm the antiquity of Antarctic meteorites from the Allan Hills site. Data on three samples of Yamato meteorites gave terrestrial ages of between about 3 and 22 thousand years

[I] Terrestrial Ages of Antarctic and Hot Desert Meteorites Using Carbon-14 and Other Cosmogenic Radionuclides

The Tenth Symposium on Polar Science/Special session: [OA] Antarctic meteorites, Thur. 5 Dec. / 3F Multipurpose conference room, National Institute of Polar Researc

MATERNAL HEALTH AND ZOONOSIS

Master of Public HealthPublic Health Interdepartmental ProgramDavid G. RenterI completed my field experience at the Department of Public Health (DPH) at the Fort Riley Army Installation, Kansas. There are six sections within the DPH that each have a different job, but they all work together to protect the health of the soldiers, families, retirees, and civilian employees at Fort Riley. The six sections of the DPH are Environmental Health, Industrial Hygiene, Army Wellness Center, Army Public Health Nursing, Occupational Health, and the Army Hearing Program. Veterinary Services also works in partnership with DPH as well, but is not actually a section in the DPH. These seven different sections, in general function to provide safe work environments on post, provide counseling regarding how individuals can improve overall health and well-being, prevent injury and illness, and protect the safety of the food supplied and served on post. My capstone project focused on zoonotic concerns in maternal health. Zoonosis is any disease naturally found in animals that can infect humans. There are more than 800 zoonotic pathogens that can potentially infect humans. Pregnant women are more susceptible to zoonotic disease due to immunosuppression, making them an important group to provide education on zoonosis prevention. I created fact sheets for veterinarians and human health care providers for four zoonotic diseases, Toxoplasmosis, Leptospirosis, Q fever, and Lymphocytic Choriomeningitis. I chose these four diseases because they not only present health risks for the mother but they also pose serious risks to fetal development and viability. There are many zoonotic diseases that a pregnant woman could be infected with but these four have the most serious consequences for not only the mother’s health but the fetus’ health as well. Also, if an expecting mother practices the preventative measures for these four diseases then she has a very low risk of becoming infected with any zoonotic disease during her pregnancy. This project allowed me to combine my experience as a practicing veterinarian along with my experience from my MPH coursework and my field experience at the DPH. Researching these four diseases allowed me to use my virology, bacteriology, parasitology, and immunology knowledge from my veterinary degree and practice along with my epidemiology coursework for my MPH. My field experience also helped to tie together the research for my capstone project, my MPH coursework in Epidemiology, Social and Behavioral Bases of Public Health, and Administration of Health Care Organizations. My field experience allowed me to see the topics covered in these courses in actual day-to-day practice in a department of public health

The Induction of Tumours following the Direct Implantation of Four Chemical Carcinogens into the Uterus of Mice and the Effect of Strain and Hormones Thereon

BONSER AND ROBSON (1 950) showed that the direct implantation into the uterine horn of 20-methylcholanthrene resulted in the induction of carcinomas and sarcomas of the wall in immature mice of the CBA strain and in mature and immature outbred white mice obtained from a dealer. The introduction of crystals into the lumen by means of a " gun " induced more tumours than the injection of the chemical dissolved in lard. Immature CBA mice were more susceptible than immaturo white mice, and mature white mice more susceptible than immature. Spaying of 14 immature white mice in which crystals were the inducing agent reduced the tumour incidence, suggesting that hormonal factors were concerned in tumour induction. A brief account of the morbid anatomy and histology of the tumours was given, demonstrating that the epithelial tumours were either adenocarcinomas, which might or might not have areas of squamous metaplasia, or squamous carcinomas. The sarcomas were either fibrosarcomas of varying degree of differentiation or leiomyosarcomas. The present experiments sought to find out whether

The exposure history of the Apollo 16 site: An assessment based on methane and hydrolysable carbon

Nineteen soils from eight stations at the Apollo 16 landing site have been analyzed for methane and hydrolysable carbon. These results, in conjunction with published data from photogeology, bulk chemistry, rare gases, primordial and cosmogenic radionuclides, and agglutinate abundances have been interpreted in terms of differing contributions from three components-North and South Ray Crater ejecta and Cayley Plains material

Carbon and oxygen isotope composition of carbonates from an L6 chondrite: Evidence for terrestrial weathering from the Holbrook meteorite

Terrestrial weathering in meteorites is an important process which alters pristine elemental and isotopic abundances. The Holbrook L6 chondrite fell in 1912. Material was recovered at the time of the fall, in 1931, and 1968. The weathering processes operating on the freshly fallen meteorite in a semi-arid region of northeastern Arizona have been studied after a ground residence of 19 and 56 years. It has been shown that a large portion of the carbonate material in 7 Antarctic ordinary chondrites either underwent extensive isotopic exchange with atmospheric CO2, or formed recently in the Antarctic environment. In fact it has been demonstrated that hydrated Mg-carbonates, nesquehonite and hydromagnesite, formed in less than 40 years on LEW 85320. In order to help further constrain the effects of terrestrial weathering in meteorites, the carbon and oxygen isotopes extracted from carbonates of three different samples of Holbrook L6: a fresh sample at the time of the fall in 1912, a specimen collected in 1931, and a third specimen collected at the same site in 1968