Evaluation of GEOSAT data and application to variability of the Northeast Pacific Ocean

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1988A portion of the northeast Pacific ocean was chosen within which to evaluate and use altimetric data from the U.S. Navy Geodetic Satellite GEOSAT. The zero-order accuracy of the major GEOSAT geophysical data record (GDR) channels was verified, and occasional gaps in the altimeter coverage were noted. GEOSAT'S 17-day repeat orbit allowed use of collinear-track processing to create profiles of the difference between the sea surface height along a given satellite repeat, and the mean sea surface height along that repeat's groundtrack. Detrending of sea surface bias and tilt on each repeat reduced orbit and other long wavelength errors in the difference profiles. The corrections provided on the GEOSAT GDR were examined for their effects on the difference profiles of three test arcs. It was found that only the ocean tide, electromagnetic bias, and inverted barometer corrections varied enough over the arc lengths (~4400 km) to have any noticeable effect on the difference profiles. Only the ocean tide correction was accurate enough to warrant using it to adjust the sea surface heights. The recommended processing of GEOSAT data for the area included making the ocean tide correction, three-point block averaging successive sea surface heights, and forming the mean height profiles from 18 repeat cycles (to reduce aliasing of the M2 tidal component). A set of difference proftles for one GEOSAT arc indicated that a reasonable estimate of GEOSAT's system precision was -4.5 cm (RMS). The mid wavelength range (100-500 km) of these profiles was found to be the only range in which oceanic mesoscale features could be separated from altimeter errors. Mean alongtrack wavenumber spectra of oceanic variability for two GEOSAT arcs were compared with a SEASAT-derived regional spectrum of Fu (1983). Agreement was good, with GEOSAT showing less system noise at short wavelengths, and greater oceanic variability at long wavelengths. The GEOSAT spectra were fit well by a k-1.5 slope at wavelengths from 100 to 1000 km. Sea surface temporal variability as a function of location was compared with the SEASAT results of Cheney et al. (1983). Qualitative agreement was excellent and quantitative differences were largely accounted for. GEOSAT picked up the variability of the major current systems of the northeast Pacific, including the Alaskan, Californian, and North Equatorial currents. Error bounds on GEOSAT-derived oceanic variability showed that the effects of uncorrected electromagnetic bias, inverted barometer, and wet troposphere were significant. Further work in the areas of error modelling, orbit determination, and geoid calculation were called for

Soviet National Security Decision Making

Winston Churchill\u27s characterization of the Soviet Union as a riddle wrapped in a mystery inside an enigma may overstate Western understanding of the USSR\u27s national security decision-making. The evidence in this domain is sparse, and what we do have is incomplete. Indeed, the Soviets have taken extraordinary steps to maintain the black box that shields how and why their decisions are made. With these caveats in mind, knowledge of Soviet decision-making can be summed up in a few general statements. First, the Soviet leadership is an integrated political-military body, where political authority is dominant, but where the professional military retains an important influence. Second, the role of institutions and individuals varies within and between leaderships, according to the issue under consideration (e.g., doctrine, procurement, etc.), and between times of peace and war. The potential for evolution in the roles of institutions is particularly apparent in the current period of perestroika. Gorbachev has initiated changes that appear to be aimed at transforming the security decision-making apparatus. Finally, the historical record of decision-making in superpower crises indicates that the Soviet Union has been very cautious in confrontations with the United States, a tendency that need not prove true in future clashes

Effect of active immunization against growth hormone releasing factor on concentrations of somatotropin and insulin-like growth factor I in lactating beef cows

Two experiments were conducted to determine the effects of immunoneutralization of growth hormone-releasing factor [GRF(1–29)-NH2] on concentrations of somatotropin (ST) and insulin-like growth factor I (IGF-I) in lactating beef cows. In Experiment 1, multiparous Hereford cows were immunized against 2 mg GRF(1–29)-(Gly)4-Cys-NH2 conjugated to human serum albumin (GRFi, n=3) or 2 mg human serum albumin (HSAi, n=3) at 52 ± 1 d prior to parturition. Boosters (1 mg) were administered on days 12, 40 and 114 postpartum (pp). Serum samples were collected at 15-min intervals for 5 hr on days 18, 46 and 120 pp, followed by administration (IV) of an opioid agonist (FK33-824; 10 μg/kg) and an antagonist (naloxone; .5 mg/kg) at hours 5 and 7, respectively. A GRF-analog ([desamino-Tyr1, D-Ala2, Ala15] GRF (1–29)-NH2; 3.5 μg/kg) and arginine (.5 g/kg) were administered at hour 10 on days 47 and 121, respectively. Percentage binding of [125I]GRF (1:100 dilution of serum) 28 d after primary immunization was greater in GRFi (14.3 ± 4.9) than in HSAi (.7 ± .3) cows. Binding increased to 29.3 ± 6.5% after first booster in GRFi cows. Episodic release of ST was abolished by immunization against GRF; concentration and frequency of release of ST were lower (P125I]GRF, absence of pulsatile release of ST, low concentrations of ST and IGF-I and failure of ST to increase after IV opioid agonist or arginine

Rapid range expansion in the Great Plains narrow-mouthed toad (Gastrophryne olivacea) and a revised taxonomy for North American microhylids

We investigated genetic variation within the Great Plains narrow-mouthed toad, Gastrophryne olivacea, across its geographic range in the United States and Mexico. An analysis of mitochondrial DNA (mtDNA) from 105 frogs revealed remarkably low levels of genetic diversity in individuals inhabiting the central United States and northern Mexico. We found that this widespread matrilineal lineage is divergent (ca. 2% in mtDNA) from haplotypes that originate from the western United States and western coast of Mexico. Using a dataset that included all five species of Gastrophryne and both species of the closely related genus Hypopachus, we investigated the phylogenetic placement of G. olivacea. This analysis recovered strong support that G. olivacea, the tropically distributed G. elegans, and the temperately distributed G. carolinensisconstitute a monophyletic assemblage. However, the placement of G. pictiventris and G. usta render Gastrophryne paraphyletic with respect to Hypopachus. To complement our mitochondrial analysis, we examined a small fragment of nuclear DNA and recovered consistent patterns. In light of our findings we recommend (1) the resurrection of the nomen G. mazatlanensis Taylor (1943) for the disjunct western clade of G. olivaceaand (2) the tentative placement of G. pictiventris and G. usta in Hypopachus. To explore possible scenarios leading to low levels of genetic diversity in G. olivacea, we used mismatch distributions and Bayesian Skyline plots to examine historic population expansion and demography. Collectively these analyses suggest that G. olivacea rapidly expanded in effective population size and geographic range during the late Pleistocene or early Holocene. This hypothesis is consistent with fossil data from northern localities and contemporary observations that suggest ongoing northern expansion. Given our findings, we suspect that the rapid range expansion of G. olivacea may have been facilitated by ecological associations with open habitats and seasonal water bodies

The barrier method as a new tool to assist in career selection: covert observational study

Objective To determine if senior doctors’ parking habits and skills are associated with clinical specialty and, if so, whether observation of junior doctors’ parking could provide guidance in choice of specialty

The impact of HIV on children's education in eastern Zimbabwe

Little is known about how HIV impacts directly and indirectly on receiving, or particularly succeeding in, education in sub-Saharan Africa. To address this gap, we used multivariable logistic regression to determine the correlation between education outcomes in youth (aged 15-24) (being in the correct grade-for-age, primary school completion and having at least five "O" level passes) and being HIV-positive; having an HIV-positive parent; being a young carer; or being a maternal, paternal or double orphan, in five rounds (1998-2011) of a general population survey from eastern Zimbabwe. The fifth survey round (2009-2011) included data on children aged 6-17, which were analysed for the impacts of the above risk factors on regular attendance in primary and secondary schools and being in the correct grade-for-age. For data pooled over all rounds, being HIV-positive had no association with primary school completion, "O" level passes, or being in the correct grade-for-age in adolescents aged 16-17 years. Additionally, HIV status had no significant association with any education outcomes in children aged 6-17 surveyed in 2009-2011. In 2009-2011, being a young carer was associated with lower attendance in secondary school (69% vs. 85%, AOR: 0.44; p=0.02), whilst being a maternal (75% vs. 83%, AOR: 0.67; p<0.01), paternal (76% vs. 83%, AOR: 0.67; p=0.02) or double (75% vs. 83%, AOR: 0.68; p=0.02) orphan was associated with decreased odds of being in the correct grade-for-age. All forms of orphanhood also significantly decreased the odds of primary school completion in youths surveyed from 1998 to 2011 (all p<0.01). We found no evidence that HIV status affects education but further evidence that orphans do experience worse education outcomes than other children. Combination approaches that provide incentives for children to attend school and equip schools with tools to support vulnerable children may be most effective in improving education outcomes and should be developed and evaluated