3,665 research outputs found

    The choice of adopting inflation targeting in emerging economies: Do domestic institutions matter?

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    Over the last decade, a growing number of emerging countries has adopted inflation targeting as monetary policy framework. In a recent paper, Freedman and Laxton (2009) ask the question “Why Inflation Targeting?”. This paper empirically investigates this question by analyzing a large set of institutional and political factors potentially associated with a country's choice of adopting IT. Using panel data on a sample of thirty inflation targeting and non-inflation emerging countries, for the period 1980-2006, our results suggest that central bank independence, policy-makers' incentives, and characteristics of political system play an important role in the choice of IT, while the level of financial development and political stability do not seem to matter. Empirical findings are confirmed by extensive robustness tests.Inflation targeting; central bank independence; financial development; political institutions; emerging countries

    Mercury transfer from watersheds to aquatic environments following the erosion of agrarian soils: A molecular biomarker approach

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    Lake St. Pierre, an important freshwater location for sports and commercial fisheries in Canada, is composed of a 120 km2 stretchof the St. Lawrence River, located at the center of the St. Lawrence Lowlands. Receiving its waters from the St. Franc¸ ois, Yamaska, Ottawa, and St. Lawrence Rivers, it is subjected to important inputs of mercury (Hg) and suspended particles eroded from its watershed. This study aims at tracing back the origin of terrigenous Hg loadings to Lake St. Pierre. The specific phenol signatures yielded by a mild oxidation of the terrestrial organic matter (TOM) carried in the water column was used as a tracer to identify the different sources of terrigenous Hg to the lake. Our results demonstrate that most of the Hg bound to suspended particulate matter (SPM-bound Hg) found in Lake St. Pierre is associated withTOM. We were also able to distinguish the relative influence that forested soils, mainly drained by the Ottawa River, and agrarian soils, located on nearby watersheds, exert on the lake’s Hg burden. Our data strongly suggest that the erosion of vast areas of agrarian soils, drained by the Yamaska and St. Franc¸ois rivers to Lake St. Pierre, greatly facilitates the transfer of Hg from the watersheds to the lake. This study stresses the need to improve the management of agrarian soils and protect them from extensive erosion in order to preserve the integrity of the fish resources harvested in Lake St. Pierre

    Terrestrial organic matter biomarkers as tracers of Hg sources in lake sediments

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    Terrestrial organic matter (TOM) plays a key role in mercury (Hg) dynamics between watersheds and lakes. In this study we attempts to determine the role of TOM source and quality and not only quantity, in the fate and transport of total Hg (T-Hg) to boreal lakes. Integrating the watershed complexity is a daunting task. Within the scope of this project, we characterized this organic matter at a molecular level in order to determine Hg transfer conditions to the sediments. We sampled ten lakes in the Quebec boreal forest. In each lake, we took a sediment core at the deepest point in addition to analyzing T-Hg and a set of terrigenous biomarkers in recent sediments. Our results show no relationship between TOM quantity and T-Hg concentration in lake sediments. However, [T-Hg] variation is well explained by the increase of 3,5Bd/V ratios (R2 = 0.84; p\0.0002) and the decrease of C/V ratios (R2 = 0.5; p\0.0227). Our study shows that TOM source and quality are determinant for Hg loadings in lake sediments. More precisely, increasing TOM derived from humified soil horizons explains most of Hg level variation within sediments

    Integrated transfers of terrigenous organic matter to lakes at their watershed level: A combined biomarker and GIS analysis

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    Terrigenous organic matter (TOM) transfer from a watershed to a lake plays a key role in contaminants fate and greenhouse gazes emission in these aquatic ecosystems. In this study, we linked physiographic and vegetation characteristics of a watershed with TOM nature deposited in lake sediments. TOM was characterized using lignin biomarkers as indicators of TOM sources and state of degradation. Geographical information system (GIS) also allowed us to integrate and describe the landscape morpho-edaphic characteristics of a defined drainage basin. Combining these tools we found a significant and positive relationship (R2 = 0.65, p < 0.002) between mean slope of the watershed and the terrigenous fraction estimated by Λ8 in recent sediments. The mean slope also correlated with the composition of TOM in recent sediments as P/(V + S) and 3,5Bd/V ratios significantly decreased with the steepness of the watersheds (R2 = 0.57, p < 0.021 and R2 = 0.71, p < 0.004, respectively). More precisely, areas with slopes comprised between 4° and 10° have a major influence on TOM inputs to lakes. The vegetation composition of each watershed influenced the composition of recent sediments of the sampled lakes. The increasing presence of angiosperm trees in the watershed influenced the export of TOM to the lake as Λ8 increased significantly with the presence of this type of vegetation (R2 = 0.44, p < 0.019). A similar relationship was also observed with S/V ratios, an indicator of angiosperm sources for TOM. The type of vegetation also greatly influenced the degradation state of OM. In this study, we were able to determine that low-sloped areas (0–2°) act as buffer zones for lignin inputs and by extension for TOM loading to sediments. The relative contribution of TOM from the soil organic horizons also increased in steeper watersheds. This study has significant implications in our understanding of the fate of TOM in lacustrine ecosystems

    A rare variant of the mtDNA HVS1 sequence in the hairs of Napoléon's family

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    This paper describes the finding of a rare variant in the sequence of the hypervariable segment (HVS1) of mitochondrial (mtDNA) extracted from two preserved hairs, authenticated as belonging to the French Emperor Napoléon I (Napoléon Bonaparte). This rare variant is a mutation that changes the base C to T at position 16,184 (16184C→T), and it constitutes the only mutation found in this HVS1 sequence. This mutation is rare, because it was not found in a reference database (P < 0.05). In a personal database (M. Pala) comprising 37,000 different sequences, the 16184C→T mutation was found in only three samples, thus in this database the mutation frequency was 0.00008%. This mutation 16184C→T was also the only variant found subsequently in the HVS1 sequences of mtDNAs extracted from Napoléon's mother (Letizia) and from his youngest sister (Caroline), confirming that this mutation is maternally inherited. This 16184C→T variant could be used for genetic verification to authenticate any doubtful material and determine whether it should indeed be attributed to Napoléon

    Futur du nucléaire - Nucléaire du futur

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    Ecole de Physique Les Houches SFP- SFEN-PACE-CEA-IN2P3 Région Rhône-AlpesL'énergie nucléaire peut jouer un rôle important dans un futur proche pour la production massive d'énergie au niveau mondial. Pour cela, elle devra satisfaire un certain nombre de critères généraux qui ont été définis par les organismes internationaux (IAEA, le Forum International Génération IV), et qui sont : une sûreté accrue, la durabilité par l'utilisation des noyaux fertiles, une bonne gestion des déchets, un champ élargi d'utilisations, une rentabilité économique acceptable et la résistance à la prolifération. Plusieurs concepts sont à l'étude voire en développement pour essayer de répondre à ces critères au sein de collaborations internationales plus ou moins larges. Après une présentation du contexte énergétique et de son futur au niveau mondial, ce papier exposera les arguments en faveur d'un futur du nucléaire en détaillant les avantages de cette forme de production d'énergie, avant une présentation des principaux systèmes en cours d'étude pour le nucléaire du futur

    Fourier optics approaches to enhanced depth-of-field applications in millimetre-wave imaging and microscopy

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    In the first part of this thesis millimetre-wave interferometric imagers are considered for short-range applications such as concealed weapons detection. Compared to real aperture systems, synthetic aperture imagers at these wavelengths can provide improvements in terms of size, cost, depth-of-field (DoF) and imaging flexibility via digitalrefocusing. Mechanical scanning between the scene and the array is investigated to reduce the number of antennas and correlators which drive the cost of such imagers. The tradeoffs associated with this hardware reduction are assessed before to jointly optimise the array configuration and scanning motion. To that end, a novel metric is proposed to quantify the uniformity of the Fourier domain coverage of the array and is maximised with a genetic algorithm. The resulting array demonstrates clear improvements in imaging performances compared to a conventional power-law Y-shaped array. The DoF of antenna arrays, analysed via the Strehl ratio, is shown to be limited even for infinitely small antennas, with the exception of circular arrays. In the second part of this thesis increased DoF in optical systems with Wavefront Coding (WC) is studied. Images obtained with WC are shown to exhibit artifacts that limit the benefits of this technique. An image restoration procedure employing a metric of defocus is proposed to remove these artifacts and therefore extend the DoF beyond the limit of conventional WC systems. A transmission optical microscope was designed and implemented to operate with WC. After suppression of partial coherence effects, the proposed image restoration method was successfully applied and extended DoF images are presented

    Physics and engineering of nuclear reactors at the "Ecole Nationale Supérieure de Physique de Grenoble" of the "Institut National Polytechnique de Grenoble"

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    International audienceIf the use of fossil fuels is to be limited to curtail greenhouse gas emissions, fission nuclear energy is, along with new renewable energies, one of the primary energy sources able to respond significantly to the increasing worldwide demand. In this context, it is necessary to design and evaluate new generations of nuclear reactors as defined by the Gen IV International Forum. The Energy and Nuclear Engineering (GEN) curriculum of the Ecole Nationale Supérieure de Physique de Grenoble (ENSPG), one of the nine engineering schools of the Grenoble Institute of Technology (INPG), includes a balanced blend of basic courses in energy, nuclear and thermal hydraulic engineering, together with the corresponding engineering sciences to cover the technological aspects. The objective is to train engineers who shall master not only nuclear engineering for the production of electricity but, more broadly, energy and nuclear technologies and their various application fields
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