5,670 research outputs found

    Editorial: Toward a Minor Tech

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    This journal issue addresses what we are calling "minor tech" making reference to Gilles Deleuze and Félix Guattari's essay "Kafka: Toward a Minor Literature" (written in 1975). They propose the concept of minor literature as opposed to great or established literature — the use of a major language that subverts it from within. "Becoming-minitorian" in this sense — to use a related concept from A Thousand Plateaus — involves the recognition of particular instances of power and the ability of the repressed minority to gain some degree of autonomy of expression. For our purpose, this notion of the minor is a relative position to major (or big) tech

    Before and After the Network - Editorial

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    How do we think about networks under post- digital conditions? What does this imply for research? This journal issue takes as its outset, the call of the transmediale festival to “[leave] be- hind a decade marked by a backlash against the Internet and the network society” in order to re-evaluate the limits of ‘networks’. It refers to Robert Filliou’s “The Eternal Network,” an idealistic notion from the 1960s, pointing to the interconnectedness of everyday-life actions across an emerging global world at that time. This is a good reminder that network cultures exist beyond the technical reality of network culture as we now know it despite our primary identification of networks with social media and planetary computation. By drawing on the legacies of critical and autonomous network cultures, the aim was to make the limits of Internet-based networks visible but also highlight alternatives. Is there a conceivable counter-power to networks? Which alternative technological models and cultural narratives are needed to construct the principles of end-to-end communication anew? How might the critique of networks extend to non-western contexts and reflect the limits in a global perspective? To answer such complex questions, this editorial begins by reflecting on the periodizing logic that invites us to leave behind “the backlash against the Internet.” What comes before and after the network

    Infrared Spectra of Meteoritic SiC Grains

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    We present here the first infrared spectra of meteoritic SiC grains. The mid-infrared transmission spectra of meteoritic SiC grains isolated from the Murchison meteorite were measured in the wavelength range 2.5--16.5 micron, in order to make available the optical properties of presolar SiC grains. These grains are most likely stellar condensates with an origin predominately in carbon stars. Measurements were performed on two different extractions of presolar SiC from the Murchison meteorite. The two samples show very different spectral appearance due to different grain size distributions. The spectral feature of the smaller meteoritic SiC grains is a relatively broad absorption band found between the longitudinal and transverse lattice vibration modes around 11.3 micron, supporting the current interpretation about the presence of SiC grains in carbon stars. In contrast to this, the spectral feature of the large (> 5 micron) grains has an extinction minimum around 10 micron. The obtained spectra are compared with commercially available SiC grains and the differences are discussed. This comparison shows that the crystal structure (e.g., beta-SiC versus alpha-SiC) of SiC grains plays a minor role on the optical signature of SiC grains compared to e.g. grain size.Comment: 7 pages, 6 figures. To appear in A&

    Phase fluctuations in atomic Bose gases

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    We improve on the Popov theory for partially Bose-Einstein condensed atomic gases by treating the phase fluctuations exactly. As a result, the theory becomes valid in arbitrary dimensions and is able to describe the low-temperature crossover between three, two and one-dimensional Bose gases, which is currently being explored experimentally. We consider both homogeneous and trapped Bose gases.Comment: 4 pages. Title changed Major changes involve extension of theory to include trapped Bose gases. Deletion of reference to and comparison with hydrogen experiment. Due to these changes, second author added. Modified manuscript accepted for PR

    Efficient calculation of local dose distribution for response modelling in proton and ion beams

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    We present an algorithm for fast and accurate computation of the local dose distribution in MeV beams of protons, carbon ions or other heavy-charged particles. It uses compound Poisson-process modelling of track interaction and succesive convolutions for fast computation. It can handle mixed particle fields over a wide range of fluences. Since the local dose distribution is the essential part of several approaches to model detector efficiency or cellular response it has potential use in ion-beam dosimetry and radiotherapy.Comment: 9 pages, 3 figure

    Naturally-phasematched second harmonic generation in a whispering gallery mode resonator

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    We demonstrate for the first time natural phase matching for optical frequency doubling in a high-Q whispering gallery mode resonator made of Lithium Niobate. A conversion efficiency of 9% is achieved at 30 micro Watt in-coupled continuous wave pump power. The observed saturation pump power of 3.2 mW is almost two orders of magnitude lower than the state-of-the-art. This suggests an application of our frequency doubler as a source of non-classical light requiring only a low-power pump, which easily can be quantum noise limited. Our theoretical analysis of the three-wave mixing in a whispering gallery mode resonator provides the relative conversion efficiencies for frequency doubling in various modes

    Improving information/disturbance and estimation/distortion trade-offs with non universal protocols

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    We analyze in details a conditional measurement scheme based on linear optical components, feed-forward loop and homodyne detection. The scheme may be used to achieve two different tasks. On the one hand it allows the extraction of information with minimum disturbance about a set of coherent states. On the other hand, it represents a nondemolitive measurement scheme for the annihilation operator, i.e. an indirect measurement of the Q-function. We investigate the information/disturbance trade-off for state inference and introduce the estimation/distortion trade-off to assess estimation of the Q-function. For coherent states chosen from a Gaussian set we evaluate both information/disturbance and estimation/distortion trade-offs and found that non universal protocols may be optimized in order to achieve better performances than universal ones. For Fock number states we prove that universal protocols do not exist and evaluate the estimation/distortion trade-off for a thermal distribution.Comment: 10 pages, 6 figures; published versio
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