Solar gravitational energy and luminosity variations

Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do so, we use the Total Solar Irradiance (TSI) as an indicator of luminosity. Considering that most of the authors have explained the largest part of the TSI modulation with magnetic network (spots and faculae) but not the whole, we could set constraints on radius and effective temperature variations (dR, dT). However computations show that the amplitude of solar irradiance modulation is very sensitive to photospheric temperature variations. In order to understand discrepancies between our best fit and recent observations of Livingston et al. (2005), showing no effective surface temperature variation during the solar cycle, we investigated small effective temperature variation in irradiance modeling. We emphasized a phase-shift (correlated or anticorrelated radius and irradiance variations) in the (dR, dT)-parameter plane. We further obtained an upper limit on the amplitude of cyclic solar radius variations, deduced from the gravitational energy variations. Our estimate is consistent with both observations of the helioseismic radius through the analysis of f-mode frequencies and observations of the basal photospheric temperature at Kitt Peak. Finally, we suggest a mechanism to explain faint changes in the solar shape due to variation of magnetic pressure which modifies the granules size. This mechanism is supported by our estimate of the asphericity-luminosity parameter, which implies an effectiveness of convective heat transfer only in very outer layers of the Sun.Comment: 17 pages, 2 figure, 1 table, published in New Astronom

2D characterization of near-surface V P/V S: surface-wave dispersion inversion versus refraction tomography

International audienceThe joint study of pressure (P-) and shear (S-) wave velocities (Vp and Vs ), as well as their ratio (Vp /Vs), has been used for many years at large scales but remains marginal in near-surface applications. For these applications, and are generally retrieved with seismic refraction tomography combining P and SH (shear-horizontal) waves, thus requiring two separate acquisitions. Surface-wave prospecting methods are proposed here as an alternative to SH-wave tomography in order to retrieve pseudo-2D Vs sections from typical P-wave shot gathers and assess the applicability of combined P-wave refraction tomography and surface-wave dispersion analysis to estimate Vp/Vs ratio. We carried out a simultaneous P- and surface-wave survey on a well-characterized granite-micaschists contact at Ploemeur hydrological observatory (France), supplemented with an SH-wave acquisition along the same line in order to compare Vs results obtained from SH-wave refraction tomography and surface-wave profiling. Travel-time tomography was performed with P- and SH- wave first arrivals observed along the line to retrieve Vtomo p and Vtomo s models. Windowing and stacking techniques were then used to extract evenly spaced dispersion data from P-wave shot gathers along the line. Successive 1D Monte Carlo inversions of these dispersion data were performed using fixed Vp values extracted from Vtomo p the model and no lateral constraints between two adjacent 1D inversions. The resulting 1D Vsw s models were then assembled to create a pseudo-2D Vsw s section, which appears to be correctly matching the general features observed on the section. If the pseudo-section is characterized by strong velocity incertainties in the deepest layers, it provides a more detailed description of the lateral variations in the shallow layers. Theoretical dispersion curves were also computed along the line with both and models. While the dispersion curves computed from models provide results consistent with the coherent maxima observed on dispersion images, dispersion curves computed from models are generally not fitting the observed propagation modes at low frequency. Surface-wave analysis could therefore improve models both in terms of reliability and ability to describe lateral variations. Finally, we were able to compute / sections from both and models. The two sections present similar features, but the section obtained from shows a higher lateral resolution and is consistent with the features observed on electrical resistivity tomography, thus validating our approach for retrieving Vp/Vs ratio from combined P-wave tomography and surface-wave profiling

Assessing personal retirement savings plans: the portuguese case

Mestrado em Economia Monetária e FinanceiraThis thesis highlights the insights and shortcomings of personal retirement savings plans (PRSP) structure, operations and performance. These schemes were, at first, established in 1989, with the purpose of encouraging personal savings and, at the same time, complementing the traditional system of pension provision. Because of their voluntary nature, the state offered a special fiscal regime to PRSP in order to promote individuals' reliance on private pension savings. PRSP are administered by pension plan sponsors. Together with investment managers, they find that their privileged access to information and to sophisticated techniques of performance evaluation allows them to achieve superior performances (for a portfolio security) than the ones reached by a financially myopic individual. To investigate this point, an analysis was conducted on return, risk, security selection and market timing performance of a sample of 20 representative personal retirement savings funds (PRSF), hold in the form of pension funds. This thesis begins with a brief debate on the impact of demographic evolution in the Portuguese pension system, with a special reference to the third pillar of pension protection. Then, it portrayed PRSP status quo and growth trends, and pointed out some criticisms and an alternative to these schemes. The final section examines PRSF performance. It starts with a brief description on the data, methodology and data limitations, followed by a literature review on portfolio performance measures and market timing. Using a time series regression on PRSF gross returns, some illustrative results are presented and identified the potential distortionary outcome of portfolio performance measures.Esta tese procura salientar as virtudes e debilidades inerentes à estrutura, modus operandis e desempenho dos planos de poupança reforma (PPR). Estabelecidos, pela primeira vez, em 1989, estes planos propunham-se a estimular a poupança voluntária bem como a complementar os esquemas tradicionais de provisão de pensões. Por serem planos de subscrição voluntários, o estado concedeu-lhes um regime fiscal especial a fim de promover a confiança dos indivíduos neste tipo de poupança privada para a velhice. Os PPR são geridos por entidades gestoras de fundos de pensões que, juntamente com os gestores de investimento, consideram que o seu acesso privilegiado à informação e às técnicas sofisticadas de avaliação do desempenho das carteiras lhes permite obter um desempenho superior àquele que seria obtido por um individuo com miopia financeira. Para investigar este facto, foram analisados o rendimento, risco, selecção individual e market timing de uma amostra composta por 20 fundos de poupança reforma (FPR), detido sobre a forma de fundos de pensões. A tese começa com uma breve discussão sobre o impacto da evolução demográfica no sistema de pensões nacionais, com especial referência para o terceiro pilar de protecção social. Segue-se, uma descrição sobre o status quo e as tendências de crescimento dos PPR. São também apontadas algumas críticas aos PPR bem como uma alternativa a estes esquemas complementares. Por fim, analisa-se a desempenho dos PPR, com uma breve descrição sobre os dados, metodologia adoptada e respectivas limitações. Segue-se uma revisão da literatura referente à avaliação do desempenho de carteiras e ao market timing. Tendo por base uma regressão temporal sobre o rendimento bruto dos FPR, são ilustrados os resultados alcançados e identificados os possíveis desfechos distorcionários que podem decorrer das medidas de avaliação do desempenho das carteiras

EU-Pacific Climate Change Policy and Engagement : a Social Science and Humanities review

Report for EU Framework 7 funded ECOPAS (European Consortium for Pacific Studies), Deliverable D3.311, 2013.This short report provides an overview and review of EU-Pacific Climate Change Policy and Engagement from a Social Science and Humanities perspective. Alongside an outline of the historical background and contemporary mechanisms that frame EU- Pacific partnership relations in reference to climate change, this report provides an outline of the SSH research literature produced in respect of Pacific peoples responses to climate change, and across the academy more generally. Finally, this report provides a commentary on the characteristics of current discourses carried by policy and engagement, and an analysis of the distinctive features that the SSH perspective reveals and which emerge from a close understanding of Pacific peoples’ own concerns. The review suggests how EU-Pacific engagement might draw upon SSH research evidence and methods to better approach these emerging policy concerns.Othe

Baseline 2000 Background Report: The Status of Integrated Coastal Management as an International Practice (Second Iteration)

The Coastal Zone Canada 2000 Conference occurred in Saint John, New Brunswick from September 17 to 22. All of the 600 registrants received a canvas packet that included four separately bound publications: the final conference program, the tradeshow program, Canadian Synopsis (a table of ICM efforts in Canada), and Baseline 2000. The Coastal Zone Canada Association organized and administered the Conference as they had done for three previous Canadian based international CZ conferences (Victoria, British Columbia in 1998, Rimouski, Québec in 1996, and Halifax, Nova Scotia in 1994). Two of the fundamental objectives of the Coastal Zone Canada Association (CZCA) and its Coastal Zone Canada (CZC) Conference Series, are that its meetings must build both on previous events and on multi-sectoral, multi-disciplinary, international gatherings that discuss and debate key challenges to integrated coastal management (ICM). The goal is to derive new guidance, tools and motivations to advance its practice. While the CZCA’s first three international conferences have, to a degree, achieved these two objectives and generated products of some value (i.e. CZC ’94 Call for Action; CZC ’96 Rimouski Declarations; CZC \u2798 Tool Kit), progress has been constrained by the absence of a baseline that is clear, coherent, well researched, and based on consensus. The CZCA decided that a baseline paper should be prepared for CZC 2000 to provide an assessment of the existing ‘state of the art’ in the practice of ICM on an international basis. State-of the-art in this context means both the current stage of development of a practice as well as newest or best practices . If this information could be obtained by the project, then a baseline could be established in the year 2000 to enable periodic assessment (such as at biennial conferences) of a number of indicators to determine ICM’s growth, development, success in overcoming challenges, and achievements. Furthermore, the information obtained from Baseline 2000 and the information obtained from the periodic assessments of changes in the ICM’s baseline should improve the efficiency and effectiveness of the practice by providing the abilities to learn from experience, particularly what works, what doesn’t work, and why. Most of Baseline 2000 (or B2K) is directed at the current stage (or status) of development of ICM as an international practice. Newest or best practices can be derived from three of the organizing frameworks proposed by B2K: 1) issues and model approaches and techniques (Section 4), common challenges to ICM (Section 7), and the index of ICM topics (Section 10)

Site-specific energy prediction for photovoltaic devices

This thesis presents an energy prediction tool for photovoltaic (PV) modules, based on the measure-correlate-predict principle. The tool allows quantification of the impact of the different environmental factors influencing PV device efficiency for different sites as they deviate from standardised test conditions and combines their effects for energy yield prediction of different module technologies operating in different climates. Amongst these environmental influences, the impact of angle of incidence has been particularly under-researched. In this work, a systematic investigation of the influence of angle of incidence on PV module performance is realised. This is achieved using both short-term module characterisation and long-term energy yield measurement campaigns. A customised purpose built dual axis tracker for mounting paired sets of modules on a fixed south-facing, 45-degree tilted rack is used to investigate the differences in module performance. The quality and quantity of the composition of the incident irradiance is described for various sky conditions at high latitude locations. Furthermore, an understanding of the entangled effects on photocurrent of both the angle of incidence and spectral variation is presented. This is achieved by analysing data from a system developed especially in this work which integrates an instantaneous all-sky mapping of irradiance from a monochromatic CCD camera with precision measurements of small-aperture normal irradiance from a collimated pyranometer in the short-term measurement campaign. The proposed energy prediction tool is validated using long-term datasets from several locations and is compared to other current methods. This was conducted under the European-funded PV-Catapult and IP Performance projects. The tool's prediction uncertainty falls within the ±5% for crystalline and ±10% for thin films, which is the same accuracy as other methods and within the measurement uncertainty of outdoor measurements

Study of aspects of the international legal and organisational response to the problem of marine pollution

SIGLEAvailable from British Library Document Supply Centre- DSC:DX84126 / BLDSC - British Library Document Supply CentreGBUnited Kingdo