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HYDROLOGY AND ORGANIC CARBON EXPORT OF AN IRREGULARLY FLOODED BRACKISH MARSH ON THE UPPER TEXAS COASTBOREY, ROLAND BORN January 1979 (has links)
No description available.
ISOTOPIC ANOMALIES FROM NUCLEAR PROCESSES IN STARSDZICZKANIEC, MARLENE January 1980 (has links)
Specific nucleosynthetic environments are examined as the sources for the anomalous xenon observed in meteorite samples. A simplified nuclear network is used to allow rapid estimation of isotopic abundances over a wide range of stellar conditions. In the zone of oxygen burning outside a stellar core that is in the silicon burning phase of energy generation, photodisintegration of xenon seed isotopes is shown to be a potential source of an overabundance of the p-isotopes of xenon. The result ('124)Xe/('126)Xe > 1 can be obtained if theoretical calculations systematically overestimate photo-alpha emission rates of certain p-isotopes of elements in the xenon region of the chart of the nuclides. Anomalies in the abundances of the heaviest xenon isotopes are shown to be a possible consequence of neutron capture reactions during explosive carbon burning in a supernova. Overabundances of ('136)Xe relative to ('134)Xe are the result of the low neutron-capture rates of N = 82 nuclei and the high photo-neurtron emission rates of N= 38 nuclei. Isotopic abundance signatures in the elements krypton, tellurium and osmium that are correlated with anomalous xenon are shown to be a plausible result of nuclear processing in the same environments that may produce anomalous xenon. The relative abundance of ('129)I associated with anomalous xenon is also examined, and predictions for anomalies in other elements based on the models presented here are given.
TWO MODELS FOR ISOTOPIC VARIATIONS IN THE LUNAR REGOLITHRAY, JAMES R. January 1980 (has links)
Two independent models are presented which attempt to account for large, apparently secular, isotopic variations recorded in lunar samples. To explain the observed long-term increase of ('15)N/('14)N, the first model considers the consequences of a "spike" contamination of the sun's outer convective zone with material greatly enhanced in ('14)N. We argue that this situation may have arisen through the following scenario: (i) The sun formed in a star cluster which included a nearby (TURN)3M(,(CIRCLE)) member. (ii) After about 10('8)y, the companion star ejected a planetary nebula enriched in ('14)N, ('22)Ne and ('4)He due to prior nuclear processing. (iii) Upon encoutnter with the solar system, the planetary nebula material was accreted onto the sun's surface and possibly into planetary/meteroitic source matter. The predominant effect was a sizeable decrease of ('15)N/('14)N in the solar convective zone and hence in the solar wind. (iv) Subsequent mixing processes in the convective zone have slowly acted to restore the sun's original surface composition. That variation, in turn, has been recorded by solar wind N trapped in lunar soils and breccias. The second model takes note of observational evidence from the Apollo 16 site which indicates that even though TiO(,2)-rich samples from other sites show a long-term increase of ('3)He/('4)He, TiO(,2)-poor samples do not. Consequently, we regard models which envision He isotopic variations as occurring in the solar wind reservoir to be untenable. Instead, the explanation must entail the differing retentivities of high and low TiO(,2) materials for inert gases. We propose that lunar atmospheric He is ultimately responsible for secular isotopic variations in He and deduce the requirements on past solar wind flow conditions. In order for atmospheric He to have been an important source of trapped lunar gas (by ionization and subsequent acceleration a la Manka and Michel, 1970), the ancient solar wind flux must have been about 100 times greater than now. Assuming the bubble diffusion model of Tamhane and Agrawal (1979) to accurately describe gas loss from lunar soil particles, we show that the different He isotopic records of TiO(,2)-rich and -poor samples can be explained if ancient atmospheric He ions were implanted with larger energies than contemporary solar wind ions. This is equivalent to requiring that the ancient interplanetary magnetic field was larger than today by a factor greater than 4.4. Associated secular increases of ('15)N('/14)N and ('13)C/('12)C are expected but the magnitudes depend critically upon the fractions of these elements which evolve into the lunar atmosphere in the atomic form.(' )
THREE-DIMENSIONAL ASPECTS OF THE PLASTIC DEFORMATION OF ANISOTROPIC ROCKSHO, CHENG-YO January 1981 (has links)
The method of plastic upper bound analysis is developed to solve problems involving three-dimensional loading and deformation of anisotropic materials. Experiments are conducted to evaluate the applicability of the analytical results. This method is also used to predict the effect of material strength properties on the lateral deviation force on a wedge during indentation of anisotropic plastic materials. The results show that the method does provide a fairly good upper bound for the indentation force and it also gives a reasonable explanation of the experimentally observed lateral deviation force.
INERT GASES IN FIFTEEN IRON METEORITESPALMA, RUSSELL LUMIR January 1981 (has links)
The inert gases helium, neon, argon, krypton, and xenon were measured mass-spectrometrically in the metal phases of fifteen iron meteorites and in graphite and troilite mineral separates from the Odessa iron meteorite. The meteorites analyzed were chosen because of their low cosmic ray exposure ages; most had known exposure ages of less than 200 million years. The hope was that the prominent spallation component seen in prior iron meteorite inert gas measurements would be reduced enough to allow detection of a trapped gas component, should one exist. Approximately three gram samples were fused in a thoroughly out-gassed alumina crucible. Surface contamination was removed from the samples by acid treatment and by preheating the samples for two days at 300(DEGREES)C. Blank measurements were made for correction purposes before and after each sample. All of the meteorite samples show evidence of having a cosmogenic inert gas component. Small variations attributable to different trace element abundances and cosmic ray shielding are seen. Large deviations from the predicted cosmogenic compositions correlate with short cosmic ray exposure ages and often indicate the presence of a trapped atmospheric-like inert gas component. Those samples showing anomalous behavior in one inert gas tend to show anomalous behavior for all the inert gases. The inert gas data from most samples are consistent with the helium, neon, and argon concentrations being largely of cosmogenic origin and the krypton and xenon resulting from a mix of solar wind, atmospheric, and cosmogenic compositions. However, there are several meteorites which are anomalous with respect to the above interpretation. Krypton and xenon measurements had only been made in the metal phase of five iron meteorites, so determining the composition of those two gases was an important result of this work. The light krypton isotopes ('78)Kr and ('80)Kr are enriched in many samples relative to a mixture of atmospheric-solar wind and cosmogenic krypton. Prior investigations of xenon in iron meteorites had assumed only the presence of cosmogenic and atmospheric xenon, but the data from this study suggest that many xenon components may be trapped in the metal phase. The Braunau inert gas data indicate strongly that this meteorite contains primordial trapped gas. Furthermore, the Braunau xenon composition includes the admixture of a xenon component not hitherto seen in any meteorite, stony or iron. This new component is marked by a low ('128)Xe/('132)Xe ratio. The inert gases in the mineral separates from the Odessa iron meteorite also show contributions from spallation, but have distinctive components not seen in the metal phase. There are enrichments at ('80)Kr, ('82)Kr, and ('83)Kr in the troilite phase which are consistent with neutron capture on ('79)Br, ('81)Br, and ('82)Se, respectively, while a ('129)Xe excess results from ('129)I decay. A trapped gas component is strikingly evident in the neon and argon data from the graphite phase of Odessa.
Sedimentology and stratigraphy of part of the Mesozoic Fossil Bluff Group, Alexander Island, AntarcticaButterworth, P. J. January 1988 (has links)
No description available.
CHEMISTRY OF THE NATURAL AEROSOL: A CASE STUDY IN SOUTH AMERICAUnknown Date (has links)
Source: Dissertation Abstracts International, Volume: 39-11, Section: B, page: 5301. / Thesis (Ph.D.)--The Florida State University, 1978.
Julius Haast: towards a new appreciation of his life and workCaudel, Mark Edward January 2007 (has links)
Little is known about Julius Haast's life prior to his arrival in New Zealand in 1858 at the age of 36. Without knowing something about his background, it is difficult to explain his life in New Zealand. This work pursues a historical context that can more fully explain Haast's remarkably active career in New Zealand. The geological survey of the Canterbury Province, the Philosophical Institute of Canterbury and the Canterbury Museum represent Haast's major contributions to science and culture in New Zealand. Julius Haast carefully engineered his own transition from geologist to museum director within the social and political climate of Canterbury in order to remain in Christchurch where he raised his family. Heinrich von Haast's book about his father has been the accepted source of information about his father since its publication in 1948. Until recently, scholars have failed to explore beyond the scope of von Haast's biography. There is now a trend toward recognising Julius Haast as having made significant contributions to many aspects of science and society.
AN INTERNSHIP WITH THE U.S. GEOLOGICAL SURVEY, PITTSBURGH, PENNSYLVANIARogers, Megan Elizabeth 29 November 2007 (has links)
No description available.
Inter-Method Comparison of US EPA Analytical Methods 507 and 508.1 to Test for Atrazine in Kentucky Drinking WaterSuhl, Jonathan 01 August 2012 (has links)
This study examined United States Environmental Protection Agency (US EPA) methods 507 and 508.1; analytical methods used to test drinking water for Atrazine. Additionally, this study examines the seasonal variation of Atrazine in Kentucky drinking water. Atrazine is a triazine herbicide used to control and inhibit the growth of broad leaf and grassy weeds. Atrazine’s ability to be transported to community drinking water supplies makes it a significant public health issue, as it has been linked to myriad negative health endpoints ranging from endocrine disruption to various forms of cancer, including stomach and ovarian cancer. To date, there is little research examining the current methods used to test for Atrazine and its seasonal variation in drinking water. Drinking water samples previously collected by the Kentucky Division of Water and the Kentucky Geological Survey from 117 of 120 counties throughout the state from January 2000 to December 2008 were used for this study. To examine inter-method comparison between methods 507 and 508.1, samples were subjected to the Mann-Whitney U test. Median values of methods 507 and 508.1 were found to be similar (p=0.7421). To examine seasonal variation, data from each year from 2000 to 2008, as well as the entire 2000-2008 period, were analyzed using the Kruskal-Wallis One Way Analysis of Variance. Years 2000, 2002, 2003, 2004, 2007, and 2008 as well as the full 2000-2008 span were found to have significantly different Atrazine concentrations from season to season. Years 2001, 2005, and 2006 were not found to have significantly different concentrations from season to season. The 2000-2008 span was then subjected to the Seasonal Kendal Test for Trend, which determined a significant (p=0.000092) decreasing linear trend of -7.6 x 10-6 mg/L/year of Atrazine in Kentucky. Similar decreasing linear trends were seen throughout the five regions in the state during this time period as well. This study further expands on knowledge of the occurrence and persistence of Atrazine in the environment. Comparative analysis of US EPA analytical methods and the seasonal variation of Atrazine in drinking water provide a background for future research.
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