The tectonic evolution of central and Northern Madagascar and its place in the final assembly of Gondwana

Copyright © 2002 by The University of Chicago. All rights reserved.Recent work in central and northern Madagascar has identified five tectonic units of the East African Orogen (EAO), a large collisional zone fundamental to the amalgamation of Gondwana. These five units are the Antongil block, the Antananarivo block, the Tsaratanana sheet, the Itremo sheet, and the Bemarivo belt. Geochronological, lithological, metamorphic, and geochemical characteristics of these units and their relationships to each other are used as a type area to compare and contrast with surrounding regions of Gondwana. The Antananarivo block of central Madagascar, part of a broad band of pre-1000-Ma continental crust that stretches from Yemen through Somalia and eastern Ethiopia into Madagascar, is sandwiched between two suture zones we interpret as marking strands of the Neoproterozoic Mozambique Ocean. The eastern suture connects the Al-Mukalla terrane (Yemen), the Maydh greenstone belt (northern Somalia), the Betsimisaraka suture (east Madagascar), and the Palghat-Cauvery shear zone system (south India). The western suture projects the Al-Bayda terrane (Yemen) through a change in crustal age in Ethiopia to the region west of Madagascar. Our new framework for the central EAO links the Mozambique belt with the Arabian/Nubian Shield and highlights the power of tectonic analysis in unraveling the complex tectonic collage of the EAO.Alan S. Collins and Brian F. Windle

Formal proof of the AVM-1 microprocessor using the concept of generic interpreters

A microprocessor designated AVM-1 was designed to demonstrate the use of generic interpreters in verifying hierarchically decomposed microprocessor specifications. This report is intended to document the high-order language (HOL) code verifying AVM-1. The organization of the proof is discussed and some technical details concerning the execution of the proof scripts in HOL are presented. The proof scripts used to verify AVM-1 are also presented

Formal design specification of a Processor Interface Unit

This report describes work to formally specify the requirements and design of a processor interface unit (PIU), a single-chip subsystem providing memory-interface bus-interface, and additional support services for a commercial microprocessor within a fault-tolerant computer system. This system, the Fault-Tolerant Embedded Processor (FTEP), is targeted towards applications in avionics and space requiring extremely high levels of mission reliability, extended maintenance-free operation, or both. The need for high-quality design assurance in such applications is an undisputed fact, given the disastrous consequences that even a single design flaw can produce. Thus, the further development and application of formal methods to fault-tolerant systems is of critical importance as these systems see increasing use in modern society

Young blood: persuading young people to give blood by applying concepts of self-perception and social norms theories to recruitment ads

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file viewed on (June 26, 2007)Includes bibliographical references.Thesis (M.A.) University of Missouri-Columbia 2006.Dissertations, Academic -- University of Missouri--Columbia -- Journalism.Communication professionals must find ways to recruit more donors to give blood more times to continue meeting the demand for a safe and adequate blood supply. Young people could supply blood for years to come if they became regular donors so this is an important demographic to target. Previous research indicates that those who have not donated before are more likely to give if they feel pressured to adhere to social norms. Previous donors cite that they are motivated by altruism. The results of this 2 x 2 factorial experiment, which applied both of motivation types to print advertisements, showed that donors and nondonors alike rated altruistic ads higher than social norms ads. Both groups reported they were more likely to donate blood after seeing altruistic ads. Continued research is needed to determine effective messages that can reach the full range of people necessary to help keep the nation's blood supply pumping

The formal verification of generic interpreters

The task assignment 3 of the design and validation of digital flight control systems suitable for fly-by-wire applications is studied. Task 3 is associated with formal verification of embedded systems. In particular, results are presented that provide a methodological approach to microprocessor verification. A hierarchical decomposition strategy for specifying microprocessors is also presented. A theory of generic interpreters is presented that can be used to model microprocessor behavior. The generic interpreter theory abstracts away the details of instruction functionality, leaving a general model of what an interpreter does

Ordovician 40Ar/39Ar phengite ages from the blueschist-facies Ondor Sum subduction-accretion complex (Inner Mongolia) and implications for the early Paleozoic history of continental blocks in China and adjacent areas

We obtained 453.2 ± 1.8 Ma and 449.4 ± 1.8 Ma (2{sigma}) laser step-heating 40Ar/39Ar plateau ages for phengite from quartzite mylonites from the blueschist-facies Ondor Sum subduction-accretion complex in Inner Mongolia (northern China). These ages are within error of the inverse isochron ages calculated using the plateau steps and the weighted mean ages of total fusion of single grains. The compositional change from glaucophane in the cores to crossite in the rims of blue amphiboles, as revealed by electron microprobe analysis, points to decompression, probably caused by progressive exhumation of the subducted material. The Late Ordovician ages were not affected by excess argon incorporation because in all likelihood the oceanic sediments were wet on arrival at the trench and free of older detrital mica. The ca. 450 Ma ages are, hence, interpreted as the time of crystallization during mylonitization under high fluid activity at fairly low temperatures. This means that accretion of the quartzite mylonite unit occured about 200 Ma before final closure of the Paleo-Asian Ocean, amalgamation of the Siberian, Tarim and North China cratons, and formation of the end-Permian Solonker suture zone. We argue that the Early Paleozoic evolution of the Ondor Sum complex occurred along the northeastern Cimmerian margin of Gondwana, which was composed of micro-continents fringed by subduction-accretion complexes and island arcs. The later evolution took place during the building of the Eurasian continent following middle Devonian and younger rifting along the East Gondwanan margin and northward drift of the detached North China craton. An extensive review shows that this type of two-stage scenario probably also applies to the geodynamic evolution of other micro-continents like, South China, Tarim, a number of Kazakh terranes, Alashan, Qaidam and Kunlun, as well as South Kitakami and correlatives in Japan, and probably Indochina. Like the North China craton, these were bordered by Early Paleozoic subduction-accretion complexes, island arcs or contained calc-alkaline volcanic margins, like for example, the central Tienshan, North Qinling, North Qaidam-Altun, North Qilian and Kunlun belts in China, as well as the Oeyama and Miyamori ophiolites and Matsugadaira-Motai blueschist belt of Japan and the dismembered Sergeevka ophiolite of the southern part of the Russian Far East. This implies that a vast orogenic system, comprising an archipelago of micro-continents, seems to have existed along the Cimmerian margin of East Gondwana in Early Paleozoic time in which the ultrahigh-pressure metamorphism that characterizes the early evolution of many of the Asian micro-continents occurred

Formal verification of a microcoded VIPER microprocessor using HOL

The Royal Signals and Radar Establishment (RSRE) and members of the Hardware Verification Group at Cambridge University conducted a joint effort to prove the correspondence between the electronic block model and the top level specification of Viper. Unfortunately, the proof became too complex and unmanageable within the given time and funding constraints, and is thus incomplete as of the date of this report. This report describes an independent attempt to use the HOL (Cambridge Higher Order Logic) mechanical verifier to verify Viper. Deriving from recent results in hardware verification research at UC Davis, the approach has been to redesign the electronic block model to make it microcoded and to structure the proof in a series of decreasingly abstract interpreter levels, the lowest being the electronic block level. The highest level is the RSRE Viper instruction set. Owing to the new approach and some results on the proof of generic interpreters as applied to simple microprocessors, this attempt required an effort approximately an order of magnitude less than the previous one

Interactions of insecticidal spider peptide neurotoxins with insect voltage- and neurotransmitter-gated ion channels

University of Technology, Sydney. Faculty of Science.Two families of peptide neurotoxins that target insect large-conductance calcium-activated potassium channels (BKCa) have been isolated from the venom of two unrelated spiders. The ƙ-TRTX-Ec2 toxins are a family of three homologous peptides isolated from the African tarantula, Eucratoscelus longiceps and ƙ-HXTX-Hv1c is the prototypic member of a family of insect-selective neurotoxins isolated from the venom of the Blue Mountains funnel-web spider, Hadronyche versuta. This thesis describes the characterisation of these insecticidal toxins using voltage-clamp and current-clamp analysis of cockroach dorsal unpaired neurons utilising the whole-cell patch-clamp technique. The ability of these toxins to modulate the gating and kinetics of both voltage- and neurotransmitter-gated ion channels were assessed. Insect bioassays were also utilised to validate the insecticidal activities of various toxins that target KV channel subtypes in house crickets. The ƙ-TRTX-Ec2 family of toxins were found to be high affinity blockers of the insect BKCa channel while failing to modify voltage-gated sodium (NaV) and calcium (CaV) channels. ƙ-TRTX-Ec2a, -Ec2b and -Ec2c block cockroach BKCa channels with IC50 values of 3.7, 25.3 and 24.6 nM, respectively. Additionally, ƙ-TRTX-Ec2a was found to inhibit delayed-rectifier KV channel currents (IK(DR)), but only at significantly higher concentrations. ƙ-TRTX-Ec2 toxins induced voltage-independent channel block and are thus proposed to interact with the turret and/or loop region of the external vestibule of the insect BKCa channel. ƙ-HXTX-Hv1c has also been characterised to block the insect BKCa channel, while failing to modulate insect NaV and CaV channels. The unique insect-selective action of ƙ-HXTX-Hv1c involves a rare vicinal disulphide ring (Cys13-Cys14) that has been determined to act as part of the bioactive surface (pharmacophore) interacting with the molecular recognition site on the insect BKCa channel. However, despite the high affinity and selectivity for the BKCa channel it was discovered that the BKCa channel is unlikely to be the lethal target of ƙ-HXTX-Hv1c. Acute toxicity tests of classical non-phylum selective BKCa blockers such as paxilline, charybdotoxin and iberiotoxin did not induce acute toxicity in insects. Furthermore, while ƙ-HXTX-Hv1c was found to prolong action potential repolarisation, increase spontaneous firing frequency and reduce spike afterhyperpolarisation, these results were markedly reduced in the presence of the BKCa channel blocker iberiotoxin. Subsequent testing of cockroach KV channel currents revealed that ƙ-HXTX-Hv1c failed to modify sodium-activated or delayed-rectifier KV channel currents, but 1 µM ƙ-HXTX-Hv1c did produce a 29% block of ‘A-type’ fast-transient KV channel currents (IK(A)). This suggests that ƙ-HXTX-Hv1c additionally targets insect KV1- or KV4-like channel subtypes. The lethal insecticidal action of 4-AP in crickets further supports an action of ƙ-HXTX-Hv1c to block IK(A). The results of co-application experiments revealed that ƙ-HXTX-Hv1c blocks the same channel as the non-phylum selective vertebrate KV4 channel toxin, ƙ-sparatoxin-Hv1b. However, it was found that ƙ-sparatoxin-Hv1b, either alone or in combination with iberiotoxin, was not insecticidal and thus the KV4 and BKCa channels are unlikely to be the lethal targets of ƙ-HXTX-Hv1c. To determine if the lethal target was a neurotransmitter-gated ion channel, the effects of ƙ-HXTX-Hv1c were investigated on chloride-gated GABAA (GABA-Cl) and glutamate (Glu-Cl) channel currents and nAChR channel currents. It was revealed that 1 µM ƙ-HXTX-Hv1c failed to modify GABAA channel currents while causing only a moderate 21% increase in Glu-Cl channel currents. Alternately, it was found that ƙ-HXTX-Hv1c caused a concentration-dependent (EC50 183 nM) slowing of nicotinic acetylcholine receptor (nAChR) channel current decay and reversed channel desensitisation. In addition, ƙ-HXTX-Hv1c moderately increased nAChR sensitivity to nicotine. These findings are consistent with a positive allosteric modulation of insect nAChRs to slow receptor desensitisation. The nAChR is a validated insecticidal target for various agrochemical insecticides, including the allosteric modulator spinosyn A. Therefore it is believed that the lethal target of ƙ-HXTX-Hv1c is the insect nAChR, whose modulation would lead to an increase in neurotransmission consistent with the excitotoxic phenotype of the toxin. This action is possibly augmented by additional actions on BKCa and KV4 like channels to increase neuronal excitability

The composite net-veined diorite intrusives of the Julianehåb district, South Greenland

Net-veined diorite intrusive are described from a plutonic environment of Precambrian granites in the Julianehåb district of S. Greenland. They are composite, minor intrusions consisting of a central diorite flanked by margins of aplitic granodiorite and they are characterised by the presence of pillow-shaped diorite blocks form ed by granitic net-veins penetrating from the margins into the central diorite. The net-veins have not chilled the diorite, but along a few there are coarser grained margins in the diorite in which biotite, sphene and orthite have recrystallised. A contraction crack - shear plane theory is proposed to explain the formation of the net-veins. The granite material was introduced along the walls of the bodies from where it penetrated inwards through a network of contraction cracks. It was also introduced through the central parts of bodies along a set of parallel sheet fractures formed by shearing and compression of the diorite. The granitic material was produced by rheomorphism-at-depth from the recently reactivated granites of the Julianehåb district; it followed its basic parent to higher levels, where it penetrated the diorite at least partly by a process of recrystallisation and replacement