528 research outputs found

    Why Are Artists Poor? The Exceptional Economy of the Arts

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    Most artists earn very little. Nevertheless, there is no shortage of aspiring young artists. Do they give to the arts willingly or unknowingly? Governments and other institutions also give to the arts, to raise the low incomes. But their support is ineffective: subsidies only increase the artists' poverty. The economy of the arts is exceptional. Although the arts operate successfully in the marketplace, their natural affinity is with gift-giving, rather than with commercial exchange. People believe that artists are selflessly dedicated to art, that price does not reflect quality, and that the arts are free. But is it true? This unconventional multidisciplinary analysis explains the exceptional economy of the arts. Insightful illustrations from the practice of a visual artist support the analysis

    Support for artists

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    Why Are Artists Poor?

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    Most artists earn very little. Nevertheless, there is no shortage of aspiring young artists. Do they give to the arts willingly or unknowingly? Governments and other institutions also give to the arts, to raise the low incomes. But their support is ineffective: subsidies only increase the artists' poverty. The economy of the arts is exceptional. Although the arts operate successfully in the marketplace, their natural affinity is with gift-giving, rather than with commercial exchange. People believe that artists are selflessly dedicated to art, that price does not reflect quality, and that the arts are free. But is it true? This unconventional multidisciplinary analysis explains the exceptional economy of the arts. Insightful illustrations from the practice of a visual artist support the analysis

    Control over Extreme-Ultraviolet High-Harmonic Generation from Gases and Solids

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    The light source that has revolutionized attosecond science over the last decades is based on the process of high-harmonic generation (HHG), which is a unique method to generate a broadband coherent spectrum extending into the extreme-ultraviolet (XUV) range. The temporal and spatial resolution of HHG enables investigation of strong-field light-matter interaction in the ultrafast and ultrasmall dimensions, and finds applications in attosecond science, lensless imaging, and industrial metrology. Unfortunately, the intrinsic low conversion efficiency of HHG and the limited methods to control the generated XUV wavefront, slow down present research and future development of applications that are based on HHG. Control over the HHG process is essential to improve the conversion efficiency and XUV wavefront characteristics, in order to facilitate next-generation attosecond science and metrology. This thesis presents experimental techniques and results that demonstrate control over both gas-based and solid-based HHG in the extreme-ultraviolet regime. Additionally, the underlying mechanism and working principles are explained through theoretical models and simulations. In Chapter 4, we demonstrate divergence and yield optimization in polarization controlled two-color gas-based HHG. Imaging, spectroscopy, and metrology applications using HHG sources require high XUV brightness, related to the conversion efficiency and the focusability of the generated XUV pulses. We systematically investigate, both experimentally and theoretically, the effect of the relative polarization between the fundamental and its second harmonic in two-color HHG, and compare the results to a one-color configuration. In a perpendicular two-color field, the relative phase between the two colors can be used to manipulate the long or the short trajectories, allowing control over the divergence of the harmonics. In a parallel two-color field, the relative phase can be used to modify the ionization rate to select trajectories and additionally allows to enhance the total yield. Next, we describe extreme-ultraviolet shaping and imaging by HHG from nanostructured silica in Chapter 5. Tailoring of any XUV wavefront after generation is challenged by the lack of efficient optical elements and limits HHG applications. We demonstrate how HHG from a structured generation medium enables control over the phase, amplitude, and polarization properties of extreme-ultraviolet pulses. Moreover, we use the emitted patterns to reconstruct height profiles, probe the near-field confinement in nanostructures below the diffraction limit of the fundamental, and image complex structures using the coherent diffractive emission from the structures. In another experiment, we establish efficient extreme-ultraviolet high-order wavemixing from laser-dressed silica, described in Chapter 6. Solid-based HHG allows to produce a coherent, broadband, extreme-ultraviolet light source with tailored emission profiles, but is put at disadvantage due to the low conversion efficiency from infrared to XUV photons. Here, we overcome the low conversion efficiency by driving the HHG simultaneously with the fundamental and its second harmonic, in a non-collinear geometry. The observed high-order wave mixing emission follows perturbative intensity scalings and enhances the XUV efficiency by at least one order of magnitude. The underlying generation mechanism is described by a quantum theory, that reveals that solid HHG is boosted through laser-dressed states. Finally, we demonstrate transient grating high-harmonic spectroscopy in MgO in Chapter 7, and investigate how an excited carrier population influences solid-state HHG. Two crossed 266-nm pulses induce a transient grating of excited carrier population due to two-photon absorption in the MgO. The modification of the relative amplitude and phase of the harmonics at the generation plane results in diffraction in the far field. Preliminary analysis demonstrates that both the macroscopic propagation effects onto the fundamental and the microscopic generation mechanism of the HHG process contribute to the amplitude and phase modulation

    Poverty and support for artists

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    a comparison of prevalence and comorbidity rates with the DSM-IV PTSD classification in two post-conflict samples

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    Background: The World Health Organization recently proposed significant changes to the posttraumatic stress disorder (PTSD) diagnostic criteria in the 11th edition of the International Classification of Diseases (ICD-11). Objective: The present study investigated the impact of these changes in two different post-conflict samples. Method: Prevalence and rates of concurrent depression and anxiety, socio-demographic characteristics, and indicators of clinical severity according to ICD-11 in 1,075 Cambodian and 453 Colombian civilians exposed to civil war and genocide were compared to those according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Results: Results indicated significantly lower prevalence rates under the ICD-11 proposal (8.1% Cambodian sample and 44.4% Colombian sample) compared to the DSM-IV (11.2% Cambodian sample and 55.0% Colombian sample). Participants meeting a PTSD diagnosis only under the ICD-11 proposal had significantly lower rates of concurrent depression and a lower concurrent total score (depression and anxiety) compared to participants meeting only DSM-IV diagnostic criteria. There were no significant differences in socio- demographic characteristics and indicators of clinical severity between these two groups. Conclusions: The lower prevalence of PTSD according to the ICD-11 proposal in our samples of persons exposed to a high number of traumatic events may counter criticism of previous PTSD classifications to overuse the PTSD diagnosis in populations exposed to extreme stressors. Also another goal, to better distinguish PTSD from comorbid disorders could be supported with our data

    Meta‐analysis for Surrogacy: Accelerated Failure Time Models and Semicompeting Risks Modeling

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90527/1/j.1541-0420.2011.01633.x.pd
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