8,363 research outputs found

    Non-interferometric Test of Collapse Models in Optomechanical Systems

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    The test of modifications to quantum mechanics aimed at identifying the fundamental reasons behind the un-observability of quantum mechanical superpositions at the macro-scale is a crucial goal of modern quantum mechanics. Within the context of collapse models, current proposals based on interferometric techniques for their falsification are far from the experimental state-of-the-art. Here we discuss an alternative approach to the testing of quantum collapse models that, by bypassing the need for the preparation of quantum superposition states might help us addressing non-linear stochastic mechanisms such as the one at the basis of the continuous spontaneous localisation model.Comment: 6 pages, accepted for publication in Phys. Rev. Lett.

    Generation, regeneration and social transformation: linking theory, policy and engagement

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    The idea of working on ‘generation’ and ‘regeneration’ in the context of policy arose when the European Union launched the Next Generation EU recovery plan as a way out of COVID crisis, thus resorting to a concept that East African societies based on generational class systems have been using as reference of their main main institutional set-up. Inspired by the Rhetoric culture school, attention shifted to the cognitive structures and correlations that ‘generation’ and ‘regeneration’ evocate, for appropriate and constructive use in policy and action. This special issue collects applied ethnographic studies on the implementation of EU programmes, long-term ethnography of Candomblè religion, a study on the role of the gadaa generational class systems of the Oromo (Ethiopia), ethnography on car theft in Kanaky (New Caledonia), a collaborative ethnography of the dônga stick duelling practiced by the Mursi (Ethiopia), and a long-term ethnographic study of divination in Hamar (Ethiopia). The comparative review of the use of ‘generation’ and ‘regeneration’ in these ethnographies shows that both represent the link between past and future, providing condensed expressions of continuity of key values. Generation evokes the reproduction of society, the process of knowledge transfer, education and cultural transmission, as linked to a specific identity group or polity. Regeneration is instead activated in response to some sort of unpredictable disturbing element that breaks the normal flow of events, either as an ongoing necessity or on occasion of crises. As such, regeneration allows the idea of change and social transformation

    The quantum theory of measurement within dynamical reduction models

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    We analyze in mathematical detail, within the framework of the QMUPL model of spontaneous wave function collapse, the von Neumann measurement scheme for the measurement of a 1/2 spin particle. We prove that, according to the equation of the model: i) throughout the whole measurement process, the pointer of the measuring device is always perfectly well localized in space; ii) the probabilities for the possible outcomes are distributed in agreement with the Born probability rule; iii) at the end of the measurement the state of the microscopic system has collapsed to the eigenstate corresponding to the measured eigenvalue. This analysis shows rigorously how dynamical reduction models provide a consistent solution to the measurement problem of quantum mechanics.Comment: 24 pages, RevTeX. Minor changes mad

    Wells and ill-fare: impacts of well failures on cultivators in hard rock areas of Madhya Pradesh

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    WellsDrillingCostsGroundwater depletionWater tableGroundwater irrigationOwnershipEconomic impactSocial impactCrop managementFood security

    The Hilbert space operator formalism within dynamical reduction models

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    Unlike standard quantum mechanics, dynamical reduction models assign no particular a priori status to `measurement processes', `apparata', and `observables', nor self-adjoint operators and positive operator valued measures enter the postulates defining these models. In this paper, we show why and how the Hilbert-space operator formalism, which standard quantum mechanics postulates, can be derived from the fundamental evolution equation of dynamical reduction models. Far from having any special ontological meaning, we show that within the dynamical reduction context the operator formalism is just a compact and convenient way to express the statistical properties of the outcomes of experiments.Comment: 25 pages, RevTeX. Changes made and two figures adde

    A Modulation Scheme for Floating Source Multilevel Inverter Topology with Increased Number of Output Levels

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    This paper presented and studied a new switching scheme for floating source multilevel inverters to produce more levels with the same number of switching devices. In the proposed scheme, the function of the dc sources, except the inner one, is to build up square wave or blocks that is close in the shape to the desired sinusoidal wave. The job of the inner switching devices is to increase the number of the levels to produce smother sinusoidal wave in the inverter output. This job can be done by adding or subtracting the value of the inner dc source to/from the blocks. The topology used in this paper is based on the conventional floating source multi-level inverter using two legs. This topology and modulation technique show substantial reduction in the total harmonics distortion when the modulation technique is the hybrid method. The performance of the proposed switching scheme in generating more levels has been evaluated by PSCAD/EMTDC simulation

    Pellicle Ultrastructure of Some Euglena Species

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    SUMMARYThe pellicle of five species of Euglena, belonging to three different groups (Catilliferae, Radiatae and Serpentes), was studied by transmission electron microscopy, in order to see if pellicular morphology could be taken as a valuable character to differentiate the groups. The data demonstrate that pellicular ultrastructure is not constant within the groups, and can therefore be considered a differential character only at the level of species

    Academic and Architectural Modernization for Development: Financial and Technical Assistance to the University of Concepción, Chile, 19561968

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    The following research is part of my ongoing dissertation project, which examines the planning, design, and construction of university campuses vis-à-vis the intensification of mining and oil extraction in South America between 1945 and 1975. In this report, I offer a brief overview of the technical and financial assistance that the Ford Foundation (FF), the Rockefeller Foundation (RF), and the UN Special Fund (UNSF) gave to one of my case studies, the Universidad de Concepción (UdeC), located in mineral-rich Chile. Multiple holdings at the Rockefeller Archive Center (RAC) reveal that these organizations provided significant aid to the UdeC between 1956 and 1968—a critical period during which the technical and financial assistance programs of the US became entangled with a national developmentalist agenda that tied scientific and engineering education to economic development. The RAC holdings I explore are extremely useful in understanding the geopolitical and economic context that shaped these aid programs, the UdeC's modernization efforts, and the agendas of the multiple actors involved in this process. The textual and visual documents I analyze also underscore the critical role that modern architecture played in all of this as an enabler of the academic reform and the economic transformation of the region, and as a persuasive signifier of "development.
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