6,883 research outputs found

    Integrable three-body systems with distinct two-body forces

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    Translationally invariant one-dimensional three-body systems with mutually different pair potentials are derived that possess a third constant of motion, both classically and quantum-mechanically; a Lax pair is given, and all (even) regular solutions of the corresponding functional equation are obtained

    Integrable field theories from Poisson algebras

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    New integrable 1 + 1 dimensional classical field theories are found that include infinite dimensional analogues of N-particle Toda-and Calogero-Moser systems, as well as non-relativistic theories with an interaction that is polynomial in the first (spatial) derivative of the field. The existence, as well as the involutivity, of an infinite set of independent conserved quantities follows most easily from a 2 + 1 dimensional Lax-pair which uses as its underlying infinite dimensional Lie algebra a Poisson algebra of functions in two variables

    Emitters of VHE γ-radiation as revealed by the H.E.S.S. Galactic plane survey

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    The High Energy Stereoscopic System (H.E.S.S.) – an array of four Imaging Atmospheric Cherenkov Telescopes located in the Khomas highlands of Namibia – explores the nonthermal universe by means of very-high-energy (VHE; >100GeV) γ-ray emission. Its high sensitivity and large field-of-view make it the ideal instrument for a survey of the Milky Way in VHE γ-rays. The H.E.S.S. Galactic Plane Scan resulted in the most complete view of our Galaxy achieved so far in this energy regime. The results of this extensive survey will be presented in this work. From the 45 VHE γ-ray sources detected so far within the Galactic Plane, a short summary is given for the 19 sources detected within the framework of this thesis and three representative sources were analyzed in even more detail: HESS J1912+101 was detected in the vicinity of an energetic pulsar, suggesting a pulsar wind nebula origin of the γ-ray emission. A clear signal of VHE γ-ray emission was also detected from RCW 86, a well-known shell-type supernova remnant. And finally, HESS J1708-441 was discovered in the vicinity of the well known pulsar PSR B1706-44, but cannot be clearly associated with this strong counterpart. As the energy spectra of these sources yield most valuable information about the processes at work in the underlying astrophysical objects, extensive studies of the spectral extraction method were performed to ensure their correct determination

    Our whole house has Alzheimer's:How early-onset dementia shapes relationships of families in the Netherlands

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    Early-onset dementia, which is diagnosed if the person with dementia is younger than 65, differs from late-onset dementia in crucial ways. It comes in a variety of forms that have different symptoms, has a lower prevalence, is less well-known, and has fewer services available that are tailored to the needs of people diagnosed with it and their families. Furthermore, it comes in a different life stage in which the family still plays a more central role. Based on ethnographic fieldwork, consisting mainly of in-depth interviews with families dealing with early-onset dementia in the Netherlands, in this thesis I show the far-reaching consequences early-onset dementia has for the lives and relationships of families. I demonstrate that early-onset dementia not only affects relationships to the sick person, but also the relationship between the ‘healthy’ parent and children or relationships among siblings. But it goes further than that. I illustrate how the illness also changes relationships to friends, relatives, and colleagues, and, finally, I discuss how the socio-cultural context shapes how the impact of early-onset dementia on relationships is experienced. The theoretical contribution of this thesis is that it argues for a systemic approach to early-onset dementia, which helps to understand the ambiguities and ambivalences that family members encounter and which are difficult to grasp using an individualistic framework. This thesis underlines that in order to understand the complexities around early-onset dementia it is important to take the multiplicity of voices and perspectives of family members into consideration

    Chronic Illness as a Source of Happiness: Paradox or perfectly normal?

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    In this paper I analyse the relation between happiness and chronic illness from the perspective of medical anthropology and disability studies. By looking at the disability paradox I deconstruct society’s view of people with a disability. I argue that the disability paradox is problematic as it ignores the views of people with a disability. Moreover, such a paradox reinforces the idea that living with a chronic illness or disability is a devastating experience and that happiness and disability are mutally exclusive realities. Based on empiric examples of people who suffer from Multiple Sclerosis I demonstrate that people with a chronic illness can experience happiness in spite of illness, but also as a consequence of it.
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