Thesis (Ph. D.)--University of Southern California, 1983. / Includes bibliographical references (leaves 164-182).

Thesis (Ph. D.)--Murdoch University, 2005. / Title from PDF title page (viewed on Sept. 24, 2005). Includes bibliographical references (p. 104-120).

Thesis (Ph. D.)--University of Canterbury, 2002. / Typescript (photocopy). Includes bibliographical references (leaves [210]-225). Also available via the World Wide Web.

No description available.

According to both spectroscopic measurements and interior models, Jupiter, Saturn, Uranus and Neptune possess gaseous envelopes that are enriched in heavy elements compared to the Sun. Straightforward application of the dominant theories of gas giant formation - core accretion and gravitational instability - fail to provide the observed enrichment, suggesting that the surplus heavy elements were somehow dumped onto the planets after the envelopes were already in existence. Previous work has shown that if giant planets rapidly reached their cur rent configuration and radii, they do not accrete the remaining planetesimals efficiently enough to explain their observed heavy-element surplus. We ex plore the likely scenario that the effective accretion cross-sections of the giants were enhanced by the presence of the massive circumplanetary disks out of which their regular satellite systems formed. Perhaps surprisingly, we find that a simple model with protosatellite disks around Jupiter and Saturn can meet known constraints without tuning any parameters. Fur thermore, we show that the heavy-element budgets in Jupiter and Saturn can be matched slightly better if Saturn’s envelope (and disk) are formed roughly 0.1 — 10 Myr after that of Jupiter. We also show that giant planets forming in an initially-compact con figuration can acquire the observed enrichments if they are surrounded by similar protosatellite disks. Protosatellite disks efficiently increase the capture cross-section, and thus the metallicity, of the giant planets. Detailed models of planet formation must therefore account for the presence of such disks during the early stages of solar system formation.

Nuclear incompressibility Knm is an important parameter in the nuclear matter equation of state (EOS). The locations of the isocalar giant monopole resonance (ISGMR) and giant dipole resonance (ISGDR) of nuclei are directly related to Knm and thus can give the most effective constraint on the value of the Knm. In order to determine Knm accurately, a systematic study of the ISGMR and ISGDR over a wide range of nuclei is necessary. Alpha inelastic scattering at small angles has been successfully used to study the ISGMR of heavy and medium nuclei where the monopole resonance is concentrated in a broad peak. For light nuclei (A<40), however, ISGMR strengths are more elusive because the resonance is fragmented and extends to excitation energies above 35 MeV. Other processes give a large physical background at high excitation energy in α inelastic scattering, which makes it difficult to extract strength distributions in this range. As an isoscalar projectile (N=Z), 6Li scattering could be an alternate way to study giant resonances. A better ratio between the resonance peak and the continuum is expected in 6Li scattering due to the low particle emitting threshold. Another important motivation for 6Li scattering study is to explore the possibility of expanding current research from stable nuclei to radioactive nuclei with inverse reactions using 6Li as a target. Data for elastic scattering of 240 MeV 6Li ions and inelastic scattering to low-lying states and giant resonances was taken for 24Mg, 28Si and 116Sn. A data analysis procedure was developed for double folding calculations. The optical potential parameters for 6Li + 24Mg, 6Li + 28Si and 6Li + 116Sn scattering systems were obtained by fitting elastic scattering data. Multipole analyses were carried out for inelastic scattering to high lying isoscalar giant resonances with multipolarities L=0 - 3. The results for the ISGMR and ISGQR are in agreement with those obtained with 240 MeV α scattering, however the agreement for the ISGDR and HEOR is not so good, indicating the uncertainty in extracting these strengths. This work has shown that 240 MeV 6Li scattering is a viable way to study the ISGMR and ISGQR and can be particularly useful in rare isotope studies where 6Li can be used as the target.

No description available.

Nematodes of the genus Meloidogyne are known as “root-knot” nematodes due to the characteristic knots or galls found on the roots of infected plants. Root-knot nematodes attack over 2000 species of plants and cause over 80 billion dollars lost annually. Giant cells are feeding sites of root-knot nematodes and are enlarged multinuclear cells induced by the nematodes in susceptible host roots and that function to provide nutrients to the nematode. This thesis presents data on two techniques of studying the nuclear condition in giant cells. Colchicine was used to arrest mitosis in giant cells in a previous study. Here we test the effect of colchicine on nematode activity. The results showed that colchicine did not affect nematode egg hatch, juvenile activity, or hatch of eggs produced by treated juveniles. These results confirm that colchicine can be used to arrest mitosis in giant cells without affecting the nematode parasite. A major obstacle to the study of giant cells is collecting tissue samples that are specific to giant cells. Laser capture microdissection (LCM) is a technique that allows one to sample a single giant cell. A focused laser beam was used to collect samples of giant cell cytoplasm from fixed and sectioned tissues. RNA was then extracted from those isolated samples. Using three tomato genes as test samples, specific primers were designed to measure expression level of Rb7, LHA4, and HXK1 gene by Real-Time PCR. Expression of LHA4 and Rb7 increased with time after inoculation, and immature giant cells reached levels that were 3 and 6 times, respectively, that of cortical cells, but which were not different from root meristem cells. Expression of HXK1 did not change with time after inoculation and has the same level of that in root tip and cortical tissues. These data confirmed that the techniques of LCM coupled with RT-real-time PCR can be used to quantitate expression of genes at different stages of giant cell development without contamination from surrounding cells.

Thesis (M. Sc.)--University of Hong Kong, 1975. / Typewritten.

According to both spectroscopic measurements and interior models, Jupiter, Saturn, Uranus and Neptune possess gaseous envelopes that are enriched in heavy elements compared to the Sun. Straightforward application of the dominant theories of gas giant formation - core accretion and gravitational instability - fail to provide the observed enrichment, suggesting that the surplus heavy elements were somehow dumped onto the planets after the envelopes were already in existence. Previous work has shown that if giant planets rapidly reached their cur rent configuration and radii, they do not accrete the remaining planetesimals efficiently enough to explain their observed heavy-element surplus. We ex plore the likely scenario that the effective accretion cross-sections of the giants were enhanced by the presence of the massive circumplanetary disks out of which their regular satellite systems formed. Perhaps surprisingly, we find that a simple model with protosatellite disks around Jupiter and Saturn can meet known constraints without tuning any parameters. Fur thermore, we show that the heavy-element budgets in Jupiter and Saturn can be matched slightly better if Saturn’s envelope (and disk) are formed roughly 0.1 — 10 Myr after that of Jupiter. We also show that giant planets forming in an initially-compact con figuration can acquire the observed enrichments if they are surrounded by similar protosatellite disks. Protosatellite disks efficiently increase the capture cross-section, and thus the metallicity, of the giant planets. Detailed models of planet formation must therefore account for the presence of such disks during the early stages of solar system formation.