392,120 research outputs found
Informal gold mining and mercury pollution in Brazil
No full textThe Amazon region has been responsible for a major share of Brazilian gold production in recent years. The region has witnessed a sizable gold rush comparable only to the California gold rush last century. The gold rush has spawned a powerful informal mining sector and has attracted many people - some who have come to the region in search of wealth and some who were already there but were displaced from other, unsuccessful economicactivities. What these people encounter at the mining sites are dreadful living and working conditions. Gold mining also causes substantial environmental problems, which may persist whether gold deposits do or not. The author discusses the environmental effects of gold mining in the region, focusing on mercury pollution. Mercury, an important input in gold extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction technology will be faced primarily by future generations, because of natural chemical processes. Although removing the mercury already discharged from the Amazonian environment may be an enormous task, at least future discharges should be curtailed through the use of appropriate technology, environmental education, and a combination of command and control measures and market-based incentives. The author describes the gold extraction process and the extent of mercury use and contamination. He analyzes key elements of the environmental problem, especially the informal miner and the fish economy. Finally, he suggests a combination of command and control regulations and market-based incentives adapted to the informal gold mining economic environment. He emphasizes the need for an education campaign about the perils of using mercury and the availability of more appropriate, and inexpensive, alternative extraction technologies.Mining&Extractive Industry (Non-Energy),Montreal Protocol,Water and Industry,Coastal and Marine Resources,Primary Metals
Gold nanoprobes for theranostics
No full textGold nanoprobes have become attractive diagnostic and therapeutic agents in medicine and life sciences research owing to their reproducible synthesis with atomic level precision, unique physical and chemical properties, versatility of their morphologies, flexibility in functionalization, ease of targeting, efficiency in drug delivery and opportunities for multimodal therapy. This review highlights some of the recent advances and the potential for gold nanoprobes in theranostics
Catalytic oxidation of ethanol on gold electrode in alkaline media
No full textThis work presents a study of the catalytic oxidation of ethanol on polycrystalline gold electrode in alkaline media. The investigation was carried out by means of chronoamperometry, cyclic voltammetry, and in situ FTIR spectroscopy. The main goal was to investigate the early stages of ethanol electrooxidation, namely at fairly low potentials (E = 600 mV vs. RHE) and for moderate reaction times (t < 300 s). Chronoamperometric experiments show a current increase accompanying the increasing in the ethanol concentration up to about 2 M and then a slight decrease at 3 M. Adsorbed CO has been observed as early as about 200 mV vs. RHE and indicates that the cleavage of the C-C bond might occur, probably to a small extent, at very low overpotentials during ethanol adsorption on gold surface. The amount of dissolved acetate ions produced during the chronoamperomentry was followed by the asymmetric stretching band at 1558 cm(-1) as a function of time, and found to increase linearly with time up to 300 s. This allowed estimating the reaction order of acetate formation with respect to ethanol concentration
Giant femtosecond optical nonlinearity of gold metamaterial nanostructures
No full textWe demonstrate that the magnitude and sign of the third-order nonlinear susceptibility of plasmonic metals can be controlled by nanostructuring. By patterning a gold film on the nanoscale to support a high quality plasmonic mode, enhancement of its two-photon absorption coefficient by two orders of magnitude is realized. With a response time of <115 fs, nonlinear gold metamaterials have potential applications in ultrafast optical limiting and all-optical data processing with terahertz bandwidth
Gold Monetization and Gold Discipline
No full textThe paper is a study of the price level and relative price effects of a policy to monetize gold and fix its price at a given future time and at the then prevailing nominal price. Price movements are analyzed both during the transition to the gold standard and during the post-monetization period. The paper also explores the adjustments to fiat money which are necessary to ensure that this type of gold monetization is non-inflationary. Finally, some conditions which produce a run on the government's gold stock leading to the collapse of the gold standard and the timing of such a run are examined.
Paper Money but a Gold Debt. Italy in the Gold Standard
No full textDuring the 52 years between the Unification of the Kingdom of Italy and World War 1, the lira was legally convertible into metal for a limited period of time. Although not formally committed to gold, the lira exchange towards the gold standard countries proved remarkably stable, \223shadowing\224 gold. It is widely claimed that being one of the successful members of the gold standard circle entailed a number of advantages. If the lira was closely linked to gold, suggesting that there was only a small cost connected to adopting the gold standard, then why did Italy not make all possible efforts to resume as soon as possible and adhere more strictly to the gold standard? Italy had a large foreign debt that was basically the result of Unification. This debt was denominated in lira, but foreign holders could convert their coupons into gold at the official rate in Paris. Italy could exploit its domestic bondholders by allowing the lira to depreciate, while insisting that domestic holders of the debt accept lira. But there were limits to this process because Italians could take the coupons to Paris have them paid in gold and because payments abroad, in gold, became more expensive following depreciation. The paper explores the various measures the Italian government used to prevent arbitrage, and the strategies bondholders used to circumvent them. In the end, however, it was clear that if devaluation went too far, most of the coupons would be presented in Paris, the debt would de facto became a gold debt, and the Italian Treasury would suffer a substantial loss of gold. Hence the convenience of letting the lira float downward and exploit seignorage any time domestic conditions became more critical. At the same time it was necessary to keep depreciation within a certain range, \223shadowing\224 the lira par value.economic history gold standard convertibility debt
The colonial factor and social transformation on the Gold Coast to 1930
No full textThis thesis traces indigenous social and economic developments among the Akan and the incorporation of the territory known as the Gold Coast into the international world economy up to 1930. The focus for the thesis is threefold: developments and conflicts within the Akan social formation itself, pressures and demands by social classes in Europe calling for greater and new forms of contact with the Gold Coast and also, perhaps more importantly, processes which were the outcome of struggles and conflicts between the European colonisers and the indigenous residents on the Gold Coast.
To assess the full nature of the political, social and economic pressures linked to the incorporation of the Gold Coast into the economies of Europe, we begin the thesis by sketching in an, account of the early contact indigenous Akan social formations. We then trace and try to characterise the differentstages of colonisation and the different demands by Europe for gold, slaves and indigenous cash crop production, and how the outcome of these European demands were largely determined by the nature of
indigenous class struggles, and not simply by the wishes of actors in the so-called 'centre'. The extent and nature of indigenous slavery is explored with specific focus both upon Akan state formation, and how the Atlantic slave trade represented a change in the demands of Europe from
gold to labour to work in the Caribbean, and that at that stage of history to acquire sufficient labourers the Europeans were dependent upon indigenous forms of capture and reproduction of slave labour. We examine why, at the
turn of the nineteenth century, Europe returned to demand gold and cash crop production from the Akan and how this led to the formation of formal colonialism, which in its early stages was dependent upon indigenous relations of production and reproduction. We then trace the development
of a colonial capitalist political economy on the Gold Coast; the 'policy' of indirect rule and the two processes of commercialisation and commoditisation of Akan land and labour
Interaction of gold nanoparticles with neurons
No full textIn the last few decades, advances in nanotechnology have resulted in the production and use of inorganic nanoparticles (NPs). These NPs have been used commercially for a range of applications, particularly in the biomedical field, based on their exceptional chemical and physical properties, which are very different to that in the larger scale. Our understanding regarding the NP interaction with the cells following NP exposure, prior to their use it is very important. This was the motivation for the work carried out in this thesis. Initially, the investigation presented in the thesis involved the synthesis of spherical and hollow gold NPs, which were then capped by water soluble organic oligo-ethylene glycol ligand (OEG). The OEG-capped NPs were then functionalised by attaching a specific cell targeting peptide, lysine terminated-Tet1, on their organic corona. The surface modification of the NPs by the aforementioned ligands, was carried out so that the NPs could be employed in the biological investigations carried out in this project. PC12 and SH-SY5Y cells, neuron-like cell lines, were exposed to the synthesised gold NPs, and the fate of these NPs within the cells was studied by using transmission electron microscopy (TEM). The TEM images revealed that spheres and hollow gold NPs were found within the PC12 cells, indicating that they were able to traverse through the cell membrane. Though, the pathway and cellular processes involved could not be specifically defined due to time constrains. Furthermore, the peptide-functionalised NPs targeted the GTb1 receptors which are readily expressed on PC12 and SH-SY5Y cells. Lysine terminated Tet1-functionalised NPs uptake seemed to be greater compared to OEG-capped NPs, and they were transported to the inner part of the cell around its perinuclear region. Nevertheless, further experiments involving fluorescently tagged NPs would give us an inside on the cellular events that take place following NP exposure, over time. In addition, western blot analysis of proteins involved in a cell stress response could give us information whether the cell is under a stress when it is exposed to gold NPs.Furthermore, the application of the hyperspectral darkfield microscope designed by the Muskens group for imaging of single hollow gold NPs on a TEM grid and in a biological sample (with fixed SH-SY5Y cells), was also presented in this Thesis. The low illumination intensity used (<0:5 W/cm2) is a very good aspect of this setup for future studies with living cells and gold NPs. For example, single hollow gold NPs could be used as spectral sensors of a particular cell signalling pathway
On the efficiency of the global gold markets
No full textThis paper examines the weak-form efficiency of the global gold markets with specific focus on the random walks (RWS) and martingale difference sequence (MDS) hypotheses, and consequently, investigates the extent to which predictability or non-predictability of global daily spot gold price return series behaviour can be explained by volatilities in macroeconomic fundamentals. We apply traditional parametric variance-ratio tests and their recent non-parametric modifications based on ranks and signs to one of the largest datasets on world gold markets to-date, consisting of daily spot price series of 28 emerging and developed gold markets from January 1968 to August 2014. First, our results show that gold markets in Egypt, Indonesia, Mexico, Nepal, Pakistan, Russia, Saudi Arabia, UAE and Vietnam are not weak-form efficient neither from the perspective of the strict RWS nor in the relaxed MDS sense. By contrast, RWS and MDS hypotheses cannot be rejected for gold markets in Hong Kong, Japan, Switzerland, UK and US at the conventional rejection levels. Results for gold markets in Australia, Bahrain, Brazil, Canada, China, Germany, India, Malaysia, Singapore, South Africa, South Korea, Taiwan, Thailand and Turkey are, however, mixed. Second, our findings show that greater changes in economic fundamentals are associated with lower levels of rejecting the RWS and MDS hypotheses. Third, our evidence shows that the probability of rejecting the weak-form efficiency is higher in emerging gold markets than developed ones. Fourth, our results show that the RWS hypothesis is rejected more frequently than its MDS alternative, and thereby justifying our decision to conduct an explicit test of the RWS and MDS hypotheses. Our results are robust to estimating subsamples, overlapping rolling windows and endogeneity corrected models, as well as controlling for a number of country-specific institutional and trading factors. Our findings have crucial implications for global portfolio managers, investors, poly-makers and regulatory authorities.
Keywords Global gold markets; Macroeconomic variables; Random walks and martingales; Weak-form efficiency; Variance-ratios; Ranks and sign
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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