41,733 research outputs found

    States That Have Not Met Their Constitutional Requirements

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    States That Have Not Met Their Constitutional Requirements

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    The importance of sound financial risk management has become increasingly emphasised in recent years, especially with the financial crisis of 2007-08. The Basel Committee sets the international standards and regulations for banks and financial institutions, and in particular under market risk, they prescribe the internal application of the measure Value-at-Risk. However, the most established non-parametric Value-at-Risk model, historical simulation, has been criticised for some of its unrealistic assumptions. This thesis investigates alternative approaches for estimating non-parametric Value-at-Risk, by examining and comparing the capability of three counterbalancing weighting methodologies for historical simulation: an exponentially decreasing time weighting approach, a volatility updating method and, lastly, a more general weighting approach that enables the specification of central moments of a return distribution. With real financial data, the models are evaluated from a performance based perspective, in terms of accuracy and capital efficiency, but also in terms of their regulatory suitability, with a particular focus on the Swedish market. The empirical study shows that the capability of historical simulation is improved significantly, from both performance perspectives, by the implementation of a weighting methodology. Furthermore, the results predominantly indicate that the volatility updating model with a 500-day historical observation window is the most adequate weighting methodology, in all incorporated aspects. The findings of this paper offer significant input both to existing research on Value-at-Risk as well as to the quality of the internal market risk management of banks and financial institutions.Betydelsen av sund finansiell riskhantering har blivit alltmer betonad pĂ„ senare Ă„r, i synnerhet i och med finanskrisen 2007-08. BaselkommittĂ©n faststĂ€ller internationella normer och regler för banker och finansiella institutioner, och sĂ€rskilt under marknadsrisk föreskriver de intern tillĂ€mpning av mĂ„ttet Value-at-Risk. DĂ€remot har den mest etablerade icke-parametriska Value-at-Risk-modellen, historisk simulering, kritiserats för nĂ„gra av dess orealistiska antaganden. Denna avhandling undersöker alternativa metoder för att berĂ€kna icke-parametrisk Value-at‑Risk, genom att granska och jĂ€mföra prestationsförmĂ„gan hos tre motverkande viktningsmetoder för historisk simulering: en exponentiellt avtagande tidsviktningsteknik, en volatilitetsuppdateringsmetod, och slutligen ett mer generellt tillvĂ€gagĂ„ngssĂ€tt för viktning som möjliggör specifikation av en avkastningsfördelnings centralmoment. Modellerna utvĂ€rderas med verklig finansiell data ur ett prestationsbaserat perspektiv, utifrĂ„n precision och kapitaleffektivitet, men ocksĂ„ med avseende pĂ„ deras lĂ€mplighet i förhĂ„llande till existerande regelverk, med sĂ€rskilt fokus pĂ„ den svenska marknaden. Den empiriska studien visar att prestandan hos historisk simulering förbĂ€ttras avsevĂ€rt, frĂ„n bĂ„da prestationsperspektiven, genom införandet av en viktningsmetod. Dessutom pekar resultaten i huvudsak pĂ„ att volatilitetsuppdateringsmodellen med ett 500 dagars observationsfönster Ă€r den mest anvĂ€ndbara viktningsmetoden i alla berörda aspekter. Slutsatserna i denna uppsats bidrar i vĂ€sentlig grad bĂ„de till befintlig forskning om Value-at-Risk, liksom till kvaliteten pĂ„ bankers och finansiella institutioners interna hantering av marknadsrisk

    Cosmic Microwave Background Anisotropy Observing Strategy Assessment

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    I develop a method for assessing the ability of an instrument, coupled with an observing strategy, to measure the angular power spectrum of the cosmic microwave background (CMB). It allows for efficient calculation of expected parameter uncertainties. Related to this method is a means of graphically presenting, via the ``eigenmode window function'', the sensitivity of an observation to different regions of the spectrum, which is a generalization of the traditional practice of presenting the trace of the window function. I apply these techniques to a balloon-borne bolometric instrument to be flown this summer (MSAM2). I find that a smoothly scanning secondary is better than a chopping one and that, in this case, a very simple analytic formula provides a good (40\% or better) approximation to expected power spectrum uncertainties.Comment: Substantial revisions, LaTeX 15 pages including 3 figure

    Symmetry-enhanced supertransfer of delocalized quantum states

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    Coherent hopping of excitation rely on quantum coherence over physically extended states. In this work, we consider simple models to examine the effect of symmetries of delocalized multi-excitation states on the dynamical timescales, including hopping rates, radiative decay, and environmental interactions. While the decoherence (pure dephasing) rate of an extended state over N sites is comparable to that of a non-extended state, superradiance leads to a factor of N enhancement in decay and absorption rates. In addition to superradiance, we illustrate how the multi-excitonic states exhibit `supertransfer' in the far-field regime: hopping from a symmetrized state over N sites to a symmetrized state over M sites at a rate proportional to MN. We argue that such symmetries could play an operational role in physical systems based on the competition between symmetry-enhanced interactions and localized inhomogeneities and environmental interactions that destroy symmetry. As an example, we propose that supertransfer and coherent hopping play a role in recent observations of anomolously long diffusion lengths in nano-engineered assembly of light-harvesting complexes.Comment: 6 page

    "It isn't just consultants that need a BSc": student experiences of an Intercalated BSc

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    More medical schools are moving towards a compulsory intercalated BSc. These courses have not traditionally been aimed at those students interested in general practice and have tended to have limited clinical relevance. This paper explores the perceptions of students who undertook a BSc in primary health care using qualitative methodology comprising semi-structured interviews with students just before completion of their course. Interviews were undertaken with 24 of the 26 students who started the course over a 4-year period. All the students have finished the course and have graduated with good honours degrees. Students refine existing skills and develop new, relevant skills for medicine. The students discussed the prestige (or lack) of a BSc in this field and how the course has impacted on their career decisions. A Primary Health Care BSc such as this appears to give students an in depth and to some, a positive view of general practice and primary care. The course allowed students to develop a more critical approach to medicine and enabled them to develop skills in addition to those acquired from their undergraduate medicine course. They perceived that these skills will serve them throughout their career in whatever branch of medicine they choose
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