Development of hypogene and supergene alteration and copper mineralization patterns, Sar Cheshmeh porphyry copper deposits, Iran /

The formation of the Sar Cheshmeh porphyry Cu-Mo deposit is related to the culmination of calc-alkaline igneous activity in the Kerman region. The deposit comprises a suite of Late Cenozoic intrusive sub-volcanic and extrusive rocks emplaced into a folded series of Eocene andesitic lavas and pyroclastic sediments. The earliest stage of magmatism was emplacement of a large granodiorite stock about 29 m.y.b.p. This was followed by intrusion of two separate porphyritic bodies at 15 (Sar Cheshrneh porphyry) and 12 m.y.b.p. (Late porphyry) and a series of sub-volcanic dikes between 12 and 9 m.y.b.p. Magmatic activity terminated with multi-phase extrusion of a Pelean dacitic dome complex between 10 and 2.8 m.y.b.p. The country rocks and the earlier porphyritic intrusions are pervasively altered to biotite-rich potassium silicate (metasomatic and hydrothermal) sericite-clay, phyllic and chlorite-clay, argillic assemblages. These grade outwards to an extensive propylitic zone. Within the ore body, the later intra-. and post-mineral dikes only reach the propylitic grade. At least three different sets of quartz veins are present, including a sericite-chlorite-quartz set which locally retrogrades pervasive secondary biotite to sericite. In the hypogene zone, metasomatic and hydrothermal alteration is related to all stages of magmatism but copper mineralization and veining are restricted to a period of 15 to 9 m.y.b.p.related to the early intrusive phases. The copper mineralization and silicate alteration do not fit a simple annular ring model but have been greatly modified by, 1. The existence of an ititial, outer ring, of metasomatic alteration overprinted by an inner.ring of hydrothermal alteration and, 2. later extensive dilating effects of intra- and post-mineral dikes. The hydrothermal clay mineral assemblage in the hypogene zone is illite-chlorite-kaolinite-smectite (beidellite). Preliminary studies indicate that the amount of each of these clays varies vertically and that hydrothermal zonation of clay minerals is possible. However, these minerals alter to illite-kaolinite assemblages in the supergene sulfide zone and to more kaolinite-rich assemblages in the supergene leached zone. Hydrothermal biotite breaks down readily in the supergene zone and is not well preserved in surface outcrops. The distribution of copper minerals in the supergene sulfide enrichment zone is only partly related to rock type being more dependent on topography and the availability of fractures.

A possible role for intrinsic calcium buffers in the long- term adaptation of crayfish neurons

Increasing the impulse activity of neurons in vivo over 3 or more days causes a reduction in transmitter release that persists for days or weeks (eg. Mercier and Atwood, 1989). This effect is usually accompanied by decreased synaptic fatigue. These two changes involve presynaptic mechanisms and indicate "long-term adaptation" (LTA) of nerve terminals. Previous experiments have shown that LTA requires extracellular calcium and protein synthesis (eg. Hong and Lnenicka, Soc. Neurosci. Abstr. 17:1322) and appears to involve communication between the cell body and the nerve terminals. The present study examines the possibility that the reduction in transmitter release is caused by an -increase in the calcium buffering ability within the nerve terminals. It examines the responses of adapted and control nerve terminals to exogenously applied calcium buffer, BAPTA-AM, which decreases transmitter release (Robitialle and Charlton, 1992). If LTA increases intrinsic Ca2+-buffering, the membrane permeant form of BAPTA should have less effect on adapted nerve terminals than on controls. Experiments are performed on the phasic abdominal extensor motor neurons of the crayfish, Procambarns clarkii. BAPTA-AM decreases excitatory postsynaptic potentials (EPSP's) of the phasic extensor muscles in a dosedependent manner between 5 and 50 JLM. LTA is elicited by in vivo stimulation at 2.5 Hz for 2-4 h per day over 3 days, which reduces EPSP's by over 50%. Experiments indicate that BAPTA-AM produces no significant change in EPSP reduction in adapted neurons when compared to controls. These results do not support the hypothesis that increased daily activity alters rapid intrinsic calcium buffers, that are able to reduce transmitter output in the same manner as BAPTA.

The nucleophillic substitution of various chloroanthraquinones of their possible rearrangement via aryne intermediates

The work in this thesis deals mainly with nucleophilic substitution of chloroanthraquinones as a route to various starting materials which might rearrange, via aryne intermediates to afford fused-ring heterocy1ic carboxylic acids. 1-Amino-5-chloroanthraquinone was successfully prepared by reacting 1,5-dichloroanthraquinone with sodium aZide in ref1uxing dimethylsulfoxide (DMSO). It could also be prepared from the same starting material by reaction with ammonia (gas) in DMSO in the presence of potassium fluoride. Treatment of l-amino-5-chloroanthraquinone with potassium amide in liquid ammonia or with potassium t-butoxide in t-butylbenzene returned mainly starting material, although in the latter case some 1-amino-5-hydroxyanthraquinone was also isolated. 1-Hydroxy-5-chloroanthraquinone was ultimately prepared by diazotization of the amino-analog. It was recovered almost quantitatively after treatmenu'with potassium amide in liquid ammonia. The reaction with potassium t-butoxide in t-buty1benzene was anomalous and gave 1-hydroxyanthraquinone as the only iso1able product. Acridines were successfully prepared by the action of 70% sulfuric acid on 1,5-bis(p-toluidino)-anthraquinone and 1-p-toluidino-5- ch10roanthraquinone, and in the latter case, cleavage to give an acridinecarboxylate was attempted. Substituted anthraquinones reacted with sodium azide in sulfuric acid to give azepindiones by -NH insertion. Methods for separating and identifying isomeric mixtures of these compounds were examined. Attempted decarbonylation of selected azepindiones to give acridones gave mainly what were thought to be amino-benzophenone derivatives. Chloroanthraquinones were found to react with hexamethylphosphoramide (HMPA) to give mixtures of the dimethylamino- and methylaminoderivatives. Under the same conditions halogeno-nitrobenzenes and nitrophenols were substituted to give the appropriate dimethyl aminobenzenes, except in two cases. 3-Chloronitrobenzene reacted anomalously to give a small amount of 3,3'-dichloroazobenzene and a trace of 4-dimethylamino-nitrobenzene. Pentachlorophenol reacted to give a pentachlorophenylphosphorodiamidate in good yield.

Impact of considering the effects of latent heat on caldera-hosted hydrothermal systems

To investigate the thennal effects of latent heat in hydrothennal settings, an extension was made to the existing finite-element numerical modelling software, Aquarius. The latent heat algorithm was validated using a series of column models, which analysed the effects of penneability (flow rate), thennal gradient, and position along the two-phase curve (pressure). Increasing the flow rate and pressure increases displacement of the liquid-steam boundary from an initial position detennined without accounting for latent heat while increasing the thennal gradient decreases that displacement. Application to a regional scale model of a caldera-hosted hydrothennal system based on a representative suite of calderas (e.g., Yellowstone, Creede, Valles Grande) led to oscillations in the model solution. Oscillations can be reduced or eliminated by mesh refinement, which requires greater computation effort. Results indicate that latent heat should be accounted for to accurately model phase change conditions in hydrothennal settings.

A possible role for chemokine signalling through CXCR4 as a downstream effector of retinoic acid signalling in the regenerating tail and spinal cord of Notophthalmus viridescens

The newt, Notopthalmus viridescens is one of the few tet rapod vertebrates capable of extensive regeneration of the central nervous system, however, the factors involved in this process are still unknown. Chemokine signalling through the receptor CXCR4, has been found to be involved in the development of the central nervous system of mammals and more recently in epimorphic fin regeneration in zebrafish. We have hypothesized that the CXCR4 signalling pathway is involved in spinal cord and tail regeneration in the adul t newt , possibly as a downstream target of retinoic acid signalling. We found that CXCR4 mRNA expression was observed in the brain, spinal cord, heart, gut, liver and regenerating tail blastemas. CXCR4 expression increased over the f i rst 12 days of tail regeneration and returned to basal expression levels at day 21 of regeneration. Inhibition of CXCR4 wi th AMD3100, a specific receptor antagonist, led to a decrease in CXCR4 mRNA in the regenerating tail 14 days post amputation. Histological analysis suggests a delay in the early stages of tail and spinal cord regeneration. Spinal cord explants t reated wi th CXCL12, the ligand to CXCR4, displayed enhanced neurite outgrowth in vitro. Explants t reated wi th AMD3100 abolished any retinoic acid enhanced neurite outgrowth effects suggesting a link between these signalling pathways.

Perceived Deservingness and the Toleration of Human Rights Violations: The Problem and a Possible Solution

Despite general endorsement of universal human rights, people continue to tolerate specific human rights violations. I conducted a two-part study to investigate this issue. For Part I, I examined whether people tolerated torture (a human rights violation) based on the morality and deservingness of the target. Participants tolerated torture more when the target had committed a highly morally reprehensible transgression. This effect was mediated by the target’s perceived deservingness for harsh treatment, and held over and above participants’ abstract support for the right to humane treatment. For Part II, hypocrisy induction was used in an attempt to reduce participants’ toleration of the torture. Participants were assigned to either the hypocrisy induction or control condition. Unexpectedly, participants who tolerated the torture more in Part I reduced their toleration the most in the control condition, possibly because of consistency and floor effects. Limitations and implications of the findings are discussed.