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Submitted by Cleide Dantas (cleidedantas@ufpa.br) on 2014-05-14T12:50:05Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_RelacoesControleModelo.pdf: 3009253 bytes, checksum: d25694255eaeed83537ba55daabb9a90 (MD5) / Approved for entry into archive by Ana Rosa Silva (arosa@ufpa.br) on 2014-09-04T12:40:13Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_RelacoesControleModelo.pdf: 3009253 bytes, checksum: d25694255eaeed83537ba55daabb9a90 (MD5) / Made available in DSpace on 2014-09-04T12:40:13Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_RelacoesControleModelo.pdf: 3009253 bytes, checksum: d25694255eaeed83537ba55daabb9a90 (MD5) Previous issue date: 2002 / A formação de classes de equivalência parece ocorrer se for possível assegurar o controle consistente pelas relações de controle do tipo modelo-S+ (seleção) ou simultaneamente por ambos os tipos de relações de controle (modelo-S+ e modelo-S-). Relações de controle do tipo modelo-S- parecem dificultar a emergência de equivalência de estímulos. Este estudo pretendeu verificar os efeitos de procedimentos programados para induzir o controle exclusivo por rejeição (modelo-S-) e por seleção (modelo-S+) ou por ambos os tipos de relações de controle (modelo-S+ e modelo-S-) na formação de classes de equivalência. O estudo visou, ainda, identificar o tipo de relações de controle estabelecidos no treino. Participaram do Experimento 1 cinco estudantes da 1ª série do ensino médio. Foram utilizados três conjuntos de estímulos visuais nos treinos programados para induzir as relações modelo-S+, modelo-S- e ambas. As escolhas forma efetuadas com mouse. Nas tentativas iniciais do treino de todas as discriminações condicionais, foi utilizado um prompt que informava, a figura que deveria ser escolhida ou a figura que não deveria ser escolhida. Durante o treino programado para induzir as relações de controle modelo-S- e modelo-S+, uma máscara substituía, respectivamente, o estímulo de comparação correto e o incorreto. No treino que visava induzir ambas as relações, os dois tipos de tentativas eram apresentadas de forma randomizada. Todos os participantes foram expostos ao treino das discriminações condicionais EF, DE, CD, BC e AB, por meio do procedimento de emparelhamento com o modelo, nos três tipos de treino das relações de controle. Após o treino foram conduzidas sondas de equivalência (FA, EA, DA, CA, FB, FC, FD e FA) e as sondas das relações de controle. Cada dois participantes foram expostos a uma seqüência diferente dos treinos programados para induzir os três tipos de relações de controle. Para identificar o tipo de relação de controle estabelecido durante o treino foram utilizados os testes blank comparison e do estímulo novo. Independentemente da relação de controle estabelecida no treino, nenhum dos participantes apresentou formação de classes de equivalência. As sondas das relações de controle, no teste blank comparison, mostraram desempenhos inconsistentes em todos os participantes, nos treinos para induzir as relações de controle do tipo modelo-S-, indicou o estabelecimento de relações de controle do tipo modelo-S+ entre o estímulo modelo e a máscara. As sondas de controle, no teste do estímulo novo, mostraram desempenho inconsistente para a maioria dos participantes. Os resultados sugerem que os treinos programados não induziram as relações de controle previstas. O Experimento 2 foi conduzido com outros 6 alunos do ensino médio e teve como objetivo verificar o efeito dos treinos programados para induzir as relações de controle modelo-S+, modelo-S- e ambas na formação de classes de equivalência. O prompt verbal usado no experimento 1 foi removido e foi aplicado um pré-treino por tentativa e erro, ensinado as discriminações condicionais e mostrando o estímulo sob a máscara. As demais condições do experimento 1 foram mantidas. Dois participantes apresentaram imediata formação de classes de equivalência na condição programada para induzir relações de controle modelo-S+/modelo-S-, e um destes participantes também apresentou estes desempenhos emergentes na condição modelo- S+. Na condição modelo-S+/modelo-S- todos os participantes escolheram-S+ nas sondas de controle (teste blank comparison). Na condição modelo-S-, 3 participantes escolheram sempre a máscara, sugerindo o estabelecimento de discriminações simples entre estímulo modelo e máscara. Na condição modelo-S+, um participante escolheu apenas o S+, dois fizeram escolhas ao S+ ou ao S- e os demais mostraram inconsistências em suas escolhas. No teste do estímulo novo, na condição modelo-S+, verificaram-se escolhas consistentes para os dois participantes que mostraram imediata formação de classes de equivalência. Na condição modelo-S+, nas tentativas que avaliam o controle por seleção, quatro participantes escolheram somente o estímulo correto e os demais fizeram escolhas inconsistentes. Quando era avaliado o controle por rejeição, a maioria das escolhas foi ao S- e à janela vazia, somente um estudante escolheu o estímulo novo. Os resultados sugerem que os treinos programados para induzir a relações de controle modelo-S+ e modelo-S+/modelo-S- facilitam a formação de classes de equivalência e que o treino programado para induzir o controle modelo-Sdificulta a formação de classes. / The formation of equivalence classes seems to occur when consistent control by sample-S+ (selection) relations or simultaneous control by both (sample-S+ and sample- S-) types of controlling relations is ensured. Sample-S- controlling relations seems to prevent the emergence of stimulus equivalence. The goal of the present study was to verify the effects of programmed procedures for prompting strict control by rejection (sample-S-) and by selection (sample-S+), or both (sample-S+ and sample-S-) types of controlling relations. The study also aimed the identification of the kind of controlling relation established during training. The participants in Experiment 1 were five students of the first year of high school. Three sets of visual stimuli were used in the prompt training for the three kinds of controlling relations (sample-S+, sample-S-, and both). Responses were made using the mouse. In the initials trials of all conditional discrimination training sessions, a verbal prompt indicated which picture should – or should not – de selected. Throughout the prompt training for sample-S- as well as for sample-S+ controlling relations, either the correct or the incorrect comparison stimulus were replaced by a mask, depending on the case. In the prompting training for both controlling relations, both mask/S- and S+/mask trials types were randomly presented. All participants were exposed to the training of conditional discriminations EF, DE, CD, BC and AB, via matching-to-sample procedure, including the training of the three controlling relations types. After training, probe trials for equivalence (FA, EA. DA, CA, FB, FC, FD and FA) and controlling relations were conducted. Different sequences of prompting training sessions for the three types of controlling relations were presented to each pair of participants. The blank comparison and the novel stimulus tests were adopted for the evaluation of the kind of controlling relation established during training. The participants did not demonstrate equivalence class formation, regardless of the controlling relation established in training. In the blank comparison test after prompting training for the sample-S+ controlling relation, the controlling relations probe showed inconsistent performances for all participants. After the prompt training for the sample- S- relations, the probes indicated the establishment of sample-S+ relations between the sample stimulus and the mask. In the novel stimulus test, the probes showed inconsistent performances for most participants. The results suggest that the programmed training did not prompt the predicted controlling relations. Instead, it developed mixed, inconsistent relations, which seem to have precluded the formation of equivalence classes. The objective of Experiment 2 was to verify the effect of prompt training for the three types of controlling relations on the equivalence class formation. Six participants were exposed to a trial-and-error procedure. The verbal prompt was removed and a trialand- error pre training present the mask replacing the stimuli was implemented to teach conditional discriminations. The remaining conditions of Experiment 1 were maintained. Two participants readily demonstrated equivalence class formation in the condition programmed to develop sample-S+/ sample-S- controlling relations, one of which also demonstrated these emergent performances in the sample-S+ condition. In the blank comparison probes for the sample-S+/ sample-S- condition, all participants selected S+. In the sample-S- condition, 3 participants always selected the mask, indicating the development of sample-S+ control between the sample stimulus and the mask. In the sample-S+ condition, one participant only selected S+, two responded mostly on S+ or S-, and the remaining showed inconsistent responding. In the novel stimulus test for the sample-S+/ sample-S- condition, the two participants who had demonstrated classes equivalence formation responded consistently. In the probes to assess control by selection for the sample-S+ condition, four participants selected only the correct stimulus, and the others responded inconsistently. When control by rejection was assessed, the responses were made mostly on S- and the blank comparison. Only one participants selected the novel stimulus. The results suggest that prompting training for sample-S+ and sample-S+/ sample-S- controlling relations facilitates the formation of equivalence classes, and that the prompt training for sample-S- control prevents equivalence class formation.

The sheet metal forming process basically involves the shaping of sheet metal of various thickness and material properties into the desired contours. This metal forming process has been extensively used by the automotive industry to manufacture both car panels and parts. Over the years numerous investigations have been conducted on various aspects of the manufacturing process with varied success. In recent years the requirements on the sheet metal forming industry have headed towards improved stability in the forming process while lowering environmental burdens. Therefore the overall aim of this research was to identify a technique for developing lubricant formulations that are insensitive to the sheet metal forming process. Due to the expense of running experiments on production presses and to improve time efficiency of the process the evaluation procedure was required to be performed in a laboratory. Preliminary investigations in the friction/lubricant system identified several laboratory tests capable of measuring lubricant performance and their interaction with process variables. However, little was found on the correlation between laboratory tests and production performance of lubricants. Therefore the focus of the research switched to identifying links between the performance of lubricants in a production environment and laboratory tests. To reduce the influence of external parameters all significant process variables were identified and included in the correlation study to ensure that lubricant formulations could be desensitised to all significant variables. The significant process variables were found to be sensitive to die position, for instance: contact pressure, blank coating of the strips and surface roughness of the dies were found significant for the flat areas of the die while no variables affected friction when polished drawbeads were used. The next phase was to identify the interaction between the significant variables and the main lubricant ingredient groups. Only the fatty material ingredient group (responsible for the formation of boundary lubricant regimes) was found to significantly influence friction with no interaction between the ingredient groups. The influence of varying this ingredient group was then investigated in a production part and compared to laboratory results. The correlation between production performance and laboratory tests was found to be test dependant. With both the Flat Face Friction test and the Drawbead Simulator unaffected by changes in the lubricant formulation, while the Flat Bottom Cup test showing similar results as the production trial. It is believed that the lack of correlation between the friction tests and the production performance of the lubricant is due to the absence of bulk plastic deformation of the strip. For this reason the Ohio State University (OSU) friction test was incorporated in the lubricant evaluation procedure along with a Flat Bottom Cup test. Finally, it is strongly believed that if the lubricant evaluation procedure highlighted in this research is followed then lubricant formulations can be developed confidently in the laboratory.

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Orientador: Sergio Tonini Button / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-07T01:24:29Z (GMT). No. of bitstreams: 1 Caldin_Renato_M.pdf: 3510420 bytes, checksum: 7632c444a9b61c552c640c1faec863a9 (MD5) Previous issue date: 2006 / Resumo: Em virtude do número crescente de veículos automotores e uma legislação ambiental cada vez mais rigorosa, as indústrias automobilísticas e os centros de pesquisas avançados buscam desenvolver novos materiais e processos de fabricação que visam à produção de peças com maior resistência mecânica, melhor conformabilidade do material e a redução das espessuras dos materiais empregados na fabricação, sem comprometer a rigidez e estabilidade estrutural das carroçarias. Esse conceito tem por objetivo minimizar os custos de produção, aumentar a segurança e reduzir o peso total do conjunto montado, diminuindo os índices de emissões de poluentes lançados no meio ambiente, em decorrência da melhor relação peso x potência do veículo e proporcionando melhores condições de conforto e dirigibilidade aos usuários. Baseado nessas características, o objetivo deste estudo foi viabilizar a utilização simultânea de dois processos de fabricação não convencionais: Hidroconformação de "Tailored Welded Blank:' (TWB). Para tanto, comparou-se a conformabilidade do TWB submetido à estampagem convencional e a hidroconformação, empregando-se o Diagrama Limite de Conformação, obtido a partir do ensaio Nakazima modificado, para determinar o limite de conformação da matéria­prima, e a Frente Máxima de Deformação (FMD) para determinar a deformação máxima ocorrida nos produtos. Para isso, foi desenvolvido um ferramental híbrido que possibilita a fabricação de peças pelos métodos da estampagem convencional e da hidroconformação, a partir de chapas de aço ST -06 e ST -07 com espessuras 1,5 e 0,9mm respectivamente, soldadas a laser para compor o TWB. Com a análise comparativa entre a CLC da matéria-prima e a FMD dos produtos estampados convencionalmente e hidroconformados, foi possível identificar que a hidroconformação de chapas supera a estampagem convencional em relação a conformabilidade dos "Tailored Welded Blanks", pois permitiu obter produtos com domos mais elevados e regulares, com uma menor redução de espessura e sem o aparecimento de falhas / Abstract: The increasing number of vehic1es and a more rigorous environmental legislation, are forcing automobile industries and research centers to develop new materials and manufacturing processes to the production of parts with higher mechanical properties, better formability and sheet thickness reduction, without comprirnising the rigidity and structural stability of the auto bodies. The main objective is to minimize the production costs, to increase the safety and to reduce vehic1e weight, reducing pollutants emissions, resulting in a best relation weight x power and providing better conditions of comfort and driveability. Based in these characteristics, the objective of this work was to study the simultaneous use of two not conventional manufacturing processes: hydroforming of Tailored Welded Blank (TWB). Therefore it was compared the formability of TWB in conventional stamping and hydroforrning, from the Forming Limit Diagram (FLD), plotted from the modified Nakazima test, to determine the forming limit of the raw material, and the Maximum Front of Deformation (MFD) to determine the maximum deformation in the products. A hybrid tool was designed and assembled to manufacture parts by conventional stamping and hydroforming steel plates ST -06 and ST-07 com thickness 1,5 and 0,9mm respectively, welded by laser to form the TWBs. With the comparative analysis between FLD of the raw material and MFD of the products conventionally stamped and hydroformed, it was possible to identify that hydroforming overcomes the conventional stamping in respect to the formability of Tailored Welded Blanks, and therefore it was possible to form products with higher and regular domes, with lower reduction of thickness, and without any failures / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Anyone desiring to qualify as an accountant or auditor is required to pass an examination as approved by the Public Accountants' and Auditors' Board to establish whether candidates have attained the required standard of academic knowledge in terms of the syllabi laid down by the Board, as well as whether they are able to apply that knowledge in practice (P AAB, 1995). However each year many students fail this very important examination. The reasons for this are not clear and the purpose of this research is to determine whether: personality; vocational interests; intelligence; matriculation Mathematics and home language (English/ Afrikaans) results, predict success in the QE, by comparing a group of successful and unsuccessful QE candidates. The logistic regression, discriminant analysis and t-test statistical procedures, indicated that: warmth (A), liveliness (F), rule-consciousness (G), social boldness (H), apprehension (0), self-reliance (Q2), perfectionism (Q3), tension (Q4), computational interest, social services interest, mechanical interest, Mental Alertness and matriculation home language, are significant factors to consider when identifying candidates likely to be successful in the QE. / Industrial & Organisational Psychology / MCOM (Industrial Psychology)

- Blank Note This thesis deals with blank note (incomplete instrument) as a particular subset of promissory notes/bills of exchange. It is comprised of a brief introduction on history of securities followed by a summarization of development of prommisory note, including its legislative history in the Czech Republic. International conferences aiming to unify the subject matter are also considered. The main body of the text aims to define the incomplete instrument; the definitions itself subsequently subdivided to provide comprehensive description of form, minimal content of the instrument, demands placed on signature and on the intent of parties to create an inchoate note. A whole individual chapter investigates one of the crucial elements typical of incomplete instrument, which is authority to fill in empty spots as given by the signee to a holder. Thus, its goal is to illustrate its nature and the ways it can originate and terminate. It being the crucial issue of many litigations concerning a once incomplete promissory note, particular attention is given to termination of such authority while the largest part of this chapter looks at application of licence to fill in violation of the authority given. In this context, a brief description of possible penal repercussions follows. The thesis also...

La littérature persane est surtout connue en Occident par les excellentes traductions en français d'illustres poètes classiques comme Omar Khayyam, Roumi, Hafîz. Genre majeur de la littérature persane, la poésie s'impose pendant des siècles avec ses règles draconiennes de prosodie et de versification. Dans les années 1930, une jeune génération de poètes, sensibles aux transformations sociales, politiques, culturelles et ayant découvert la poésie et la littérature occidentales, s'est engagée dans une lutte systématique contre ces règles intangibles. Le pionnier de ce mouvement est Nimâ Yshij. Il rejette les règles de la poésie classique, aussi bien en ce qui concerne la métrique que la place de la rime. Ahmad Shâmlu, disciple de Nimâ, va plus loin en refusant même la prosodie. En rupture permanente, Shâmlu a marqué la poésie moderne persane, par son œuvre, par ses idées et par ses attitudes. Soucieux des événements de son temps et de sa société, ce poète, traducteur et directeur de revues, a lutté toute sa vie pour ses idéaux humanistes. Une anthologie de ses œuvres traduites en français permettra de faire découvrir aux amateurs ce grand poète persan moderne et contemporain. / Persian literature is best known in the West by the excellent French translations of famous classical poets like Omar Khayyam, Rumi, Hafeez. As a major genre of Persian literature, poetry has for centuries imposed draconian rules of prosody and versification. In the 1930s, younger generation of poets, sensitive to social, political and cultural changes, discovered Western poetry and literature, and engaged in a systamtic struggle against these intangible rules. the pioneer of this movment in Nima Yshij. Her rejected the rules of classical potry, where both versification and rhyme are concerned. Ahmad Shâmlu, a disciple of Nima, goes even further by refusing prosody. Breaking constantly with traditon, Shâmlu has left his mark on modern Persian poetry, in his work, and by his ideas and attitudes. Mindful of the events of his time and of his life for his humanistic ideals. An antthology of his works translatedinto French will enable poetry-lovers to discover this great modern contemporary Persian poet.

Macromolecular biomaterials often require covalent crosslinking to achieve adequate stability and mechanical strength for their given application. However, the use of auxiliary chemicals may be associated with long-term toxicity in the body. Oppositely-charged polyelectrolytes (PEs) have the advantage that they can self-crosslink electrostatically and those derived from marine organisms are an inexpensive alternative to glycosaminoglycans present in the extracellular matrix of human tissues. A range of different combinations of PEs and preparation conditions have been reported in the literature. However, although there has been some work on complex formation between chitosan (CS) and carrageenan (CRG), much of the work undertaken has ignored the effect of pH on the consequent physicochemical properties of self-crosslinked polyelectrolyte complex (PEC) gels, films and scaffolds. Chitosan is a positively-charged polysaccharide with NH3+ side groups derived from shrimp shells and, carrageenan is a negatively-charged polysaccharide with OSO3- side groups derived from red seaweed. These abundant polysaccharides possess advantageous properties such as biodegradability and low toxicity. However, at present, there is no clear consensus on the cell binding properties of CS and CRG or CS-CRG PEC materials. The aim of this study was to explore the properties of crosslinker-free PEC gels, solvent-cast PEC films and freeze-dried PEC scaffolds based on CS and CRG precursors for medical applications. The objective was to characterise the effect of pH of the production conditions on the physicochemical and biological properties of CS-CRG PECs. Experimental work focused on the interaction between PEs, the composition of PECs, the rheological properties of PEC gels and the mechanical properties of PEC films and scaffolds. In addition, cell and protein attachment to the PEC films was assessed to determine their interactions in a biological environment. For biomedical applications, these materials should ideally be stable when produced such that they can be processed to form either a film or a scaffold and have mechanical properties comparable to those of collagenous soft tissues. FTIR was used to confirm PEC formation. Zeta potential measurements indicated that the PECs produced at pH 2-6 had a high strength of electrostatic interaction with the highest occurring at pH 4-5. This resulted in stronger intra-crosslinking in the PEC gels which led to the formation of higher yield, solid content, viscosity and fibre content in PEC gels. The weaker interaction at pH 7-12 resulted in higher levels of CS incorporated into the complex and the formation of inter-crosslinking through entanglements between PEC units. This resulted in the production of strong and stiff PEC films and scaffolds appropriate for soft tissue implants. The PECs prepared at pH 7.4 and 9 also exhibited low swelling and mass loss, which was thought to be due to the high CS content and entanglements. From the range of samples tested, the PECs produced at pH 7.4 appeared to show the optimum combination of yield, stability and homogeneity for soft tissue implants. Biological studies were performed on CS, CRG and PECs prepared at pH 3, 5, 7.4 and 9. All of the PE and PEC films were found to be non-cytotoxic. When the response of three different cell types and a high binding affinity protein (tropoelastin) was evaluated; it was found that the CS-CRG PEC films displayed anti-adhesive properties. Based on these experimental observations and previous studies, a mechanistic model of the anti-adhesive behaviour of PEC surfaces was proposed. It was therefore concluded that the CS-CRG PECs produced might be suitable for non-biofouling applications.

Human activities such as mining and smelting of lead (Pb) ores and combustion of alkyllead additives in gasoline have resulted in extensive global Pb pollution. Since the late 1960's studies of polar ice and snow have been undertaken to evaluate the extent of anthropogenic Pb emissions in recent times as well as to investigate changes in anthropogenic Pb emissions in the more distant past. The polar ice sheets have been used to investigate Pb pollution as they offer a long-term record of human activity located far from pollution sources and sample aerosol emissions on a hemispheric scale. Lead isotopes have been previously used to identify sources of Pb in polar snow and ice, while new evaluations of Pb isotopic compositions in aerosols and Pb ore bodies allow more thorough evaluations of anthropogenic Pb emissions. Lead isotopic compositions and Pb and Barium (Ba) concentrations have been measured in snow and ice core samples from Law Dome, East Antarctica, to produce a detailed pollution history between 1530 AD and 1989 AD. Such a record has been produced to evaluate changes in anthropogenic Pb emission levels and sources over the past 500 years, to determine when industrial (anthropogenic) activities first began to influence Antarctica and also to investigate natural Pb fluxes to Antarctica. Additional samples were also collected from Law Dome snow and ice cores to respectively investigate seasonal variations in Pb and Ba deposition, and the influence of the 1815 AD volcanic eruption of Tambora, Indonesia. All samples were measured by thermal ionisation mass spectrometry, for which techniques were developed to reliably analyse Pb isotopic compositions in Antarctic samples containing sub-picogram per gram concentrations of Pb. / Particular attention was given to the quantity of Pb added to the samples during the decontamination and sample storage stages of the sample preparation process. These stages, including the use of a stainless steel chisel for the decontamination, contributed ~5.2 pg to the total sample analysed, amounting to a concentration increase of ~13 fg g-1. In comparison, the mass spectrometer ion source contributed typically 89 +/- 19 fg to the blank, however its influence depended upon the amount of Pb available for analysis and so had the greatest impact when small volumes of samples with a very low concentration were analysed. As a consequence of these careful investigations of the Pb blank contributions to the samples, the corrections made to the Pb isotopic ratios and concentrations measured are smaller than previously reported evaluations of Pb in Antarctica by thermal ionisation mass spectrometry. The data indicate that East Antarctica was relatively pristine until -1884 AD, after which the first influence of anthropogenic Pb in Law Dome is observed. "Natural", pre-industrial, background concentrations of Pb and Ba were - 0.4 pg/g and - 1.3 pg/g, respectively, with Pb isotopic compositions within the range 206Pb/207Pb = 1.20 - 1.25 and 208Pb/207Pb = 2.46 - 2.50 and an average rock and soil dust Pb contribution of 8-12%. A major pollution event was observed at Law Dome between 1884 and 1908 AD, elevating the Pb concentration fourfold and changing 206Pb/207Pb ratios in the ice to ~1.12. Based on Pb isotopic systematics and Pb emissions statistics, this was attributed to Pb mined at Broken Hill and smelted at Broken Hill and Port Pirie, Australia. / Anthropogenic Pb inputs to Law Dome were most significant from ~1900 to 1910 and from ~1960 to 1980. During the 20th century, Ba concentrations were consistently higher than "natural" levels. This was attributed to increased dust production, suggesting the influence of climate change and/or changes in land coverage with vegetation. Law Dome ice dated from 1814 AD to 1819 AD was analysed for Pb isotopes and Pb, Ba and Bismuth (Bi) concentrations to investigate the influence of the 1815 AD volcanic eruption of Tambora, Indonesia. The presence of volcanic debris in the core samples was observed from late-1816 AD to 1818 AD as an increase in sulphate concentrations and electrical conductivity of the ice. Barium concentrations were approximately three times higher than background levels from mid-1816 to mid1818, consistent with increased atmospheric loading of rock and soil dust, while enhanced Pb/Ba and Bi/Ba ratios, associated with deposition of volcanic debris, were observed at mid-1814 and from early-1817 to mid-1818. From the results, it appeared likely that Pb emitted from Tambora was removed from the atmosphere within the 1.6 year period required to transport aerosols to Antarctica. Increased Pb and Bi concentrations observed in Law Dome ice ~1818 AD were attributed to either increased heavy metal emissions from Mount Erebus, or increased fluxes of heavy metals to the Antarctic ice sheet resulting from climate and meteorological modifications following the Tambora eruption. / A non-continuous series of Law Dome snow core samples dating from 1980 to 9185 AD were analysed to investigate seasonal variations in the deposition of Pb and Ba. It was found that Pb and Ba at Law Dome do exhibit seasonal variations in deposition, with higher concentrations of Pb and Ba usually observed during Summer and lower concentrations of Pb and Ba usually observed during the Autumn and Spring seasons. At Law Dome, broad patterns of seasonal Pb and Ba deposition are evident however these appear to be punctuated by short-term deposition events or may even be composed of a continuum of short-term deposition events. This variability suggests that complex meteorological systems are responsible for the transport of Pb and Ba to Law Dome, and probably Antarctica in general.