17,897 research outputs found

    The impacts of animal farming: A critical overview of primary school textbooks

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    Based on a sample of 46 Portuguese schoolbooks, this study aims to understand how factory-farmed animals are presented in such books across the themes of food and health, the environment and sustainability, and animal welfare. It examines whether schoolbooks address the importance of reducing the consumption of animal-based products for a healthy diet, whether plant-based diets are recognized as healthy, whether animal welfare and agency are considered, and whether the livestock sec- tor is indicated as a major factor in environmental degradation. The findings show that schoolbooks present animals as essential for economic activities and human nutrition. Recommendations on reducing the consumption of animal-based products in consideration of the environment, sustainability and human health are very rare. Animal production is presented as benign, and the agency and welfare of factory- farmed animals are simply not addressedinfo:eu-repo/semantics/publishedVersio

    The presence of carnism on Portuguese television

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    This paper presents the results of a research about carnism on Portuguese television. It begins by presenting a case study of MasterChef program (TVI) which conveys carnism in both practices and language, and from which some characteristics of their dominant representations are described. Subsequently, the paper presents the indicators of the presence of carnism in the Portuguese television programming, between 2013 and 2014, in the TVI, RTP1, and SICS channels. The data reveals that there is the hegemony of the carnist ideology in the main channels of the Portuguese television. Also, the samples collected and viewed show no mention of the impacts of carnism in its various dimensions (non-human animals, environment, human health and sustainability).info:eu-repo/semantics/publishedVersio

    DC magnetic field generation in unmagnetized shear flows

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    The generation of DC magnetic fields in unmagnetized plasmas with velocity shear is predicted for non relativistic and relativistic scenarios either due to thermal effects or due to the onset of the Kelvin-Helmholtz instability (KHI). A kinetic model describes the growth and the saturation of the DC field. The predictions of the theory are confirmed by multidimensional particle-in-cell simulations, demonstrating the formation of long lived magnetic fields (t∼100sωpi−1t \sim 100s \omega_{pi}^{-1}) along the full longitudinal extent of the shear layer, with transverse width on the electron length scale (γ0c/ωpe\sqrt{\gamma_0}c/\omega_{pe}), reaching magnitudes eBDC/mecωpe∼β0γ0eB_{\mathrm{DC}}/m_ec\omega_{pe}\sim \beta_0\sqrt{\gamma_0}

    Between acceptance and veto: the meat perceptual dimensions

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    This paper designates and describes the perceptual dimensions (practical perceptual dimension and cultural perceptual dimension) that affects the acceptance of meat consumption and animal products, as well the (production) perceptual dimension that conditions hegemonic eating habits which may trigger the veto for the products mentioned above. I argue that the focus or the development of certain perceptions generated by consumers defines value systems, and beliefs, which influences the eating behaviors related to meat and animal products.info:eu-repo/semantics/publishedVersio

    Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets

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    Strong shear flow regions found in astrophysical jets are shown to be important dissipation regions, where the shear flow kinetic energy is converted into electric and magnetic field energy via shear instabilities. The emergence of these self-consistent fields make shear flows significant sites for radiation emission and particle acceleration. We focus on electron-scale instabilities, namely the collisionless, unmagnetized Kelvin-Helmholtz instability (KHI) and a large-scale dc magnetic field generation mechanism on the electron scales. We show that these processes are important candidates to generate magnetic fields in the presence of strong velocity shears, which may naturally originate in energetic matter outburst of active galactic nuclei and gamma-ray bursters. We show that the KHI is robust to density jumps between shearing flows, thus operating in various scenarios with different density contrasts. Multidimensional particle-in-cell (PIC) simulations of the KHI, performed with OSIRIS, reveal the emergence of a strong and large-scale dc magnetic field component, which is not captured by the standard linear fluid theory. This dc component arises from kinetic effects associated with the thermal expansion of electrons of one flow into the other across the shear layer, whilst ions remain unperturbed due to their inertia. The electron expansion forms dc current sheets, which induce a dc magnetic field. Our results indicate that most of the electromagnetic energy developed in the KHI is stored in the dc component, reaching values of equipartition on the order of 10−310^{-3} in the electron time-scale, and persists longer than the proton time-scale. Particle scattering/acceleration in the self generated fields of these shear flow instabilities is also analyzed

    Quantum Electrodynamics vacuum polarization solver

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    The self-consistent modeling of vacuum polarization due to virtual electron-positron fluctuations is of relevance for many near term experiments associated with high intensity radiation sources and represents a milestone in describing scenarios of extreme energy density. We present a generalized finite-difference time-domain solver that can incorporate the modifications to Maxwell's equations due to vacuum polarization. Our multidimensional solver reproduced in one dimensional configurations the results for which an analytic treatment is possible, yielding vacuum harmonic generation and birefringence. The solver has also been tested for two-dimensional scenarios where finite laser beam spot sizes must be taken into account. We employ this solver to explore different types of counter-propagating configurations that can be relevant for future planned experiments aiming to detect quantum vacuum dynamics at ultra-high electromagnetic field intensities

    Transverse electron-scale instability in relativistic shear flows

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    Electron-scale surface waves are shown to be unstable in the transverse plane of a shear flow in an initially unmagnetized plasma, unlike in the (magneto)hydrodynamics case. It is found that these unstable modes have a higher growth rate than the closely related electron-scale Kelvin-Helmholtz instability in relativistic shears. Multidimensional particle-in-cell simulations verify the analytic results and further reveal the emergence of mushroom-like electron density structures in the nonlinear phase of the instability, similar to those observed in the Rayleigh Taylor instability despite the great disparity in scales and different underlying physics. Macroscopic (≫c/ωpe\gg c/\omega_{pe}) fields are shown to be generated by these microscopic shear instabilities, which are relevant for particle acceleration, radiation emission and to seed MHD processes at long time-scales

    Ising Field Theory on a Pseudosphere

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    We show how the symmetries of the Ising field theory on a pseudosphere can be exploited to derive the form factors of the spin fields as well as the non-linear differential equations satisfied by the corresponding two-point correlation functions. The latter are studied in detail and, in particular, we present a solution to the so-called connection problem relating two of the singular points of the associated Painleve VI equation. A brief discussion of the thermodynamic properties is also presented.Comment: 39 pages, 6 eps figures, uses harvma

    Conditions for the onset of the current filamentation instability in the laboratory

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    Current Filamentation Instability (CFI) is capable of generating strong magnetic fields relevant to explain radiation processes in astrophysical objects and lead to the onset of particle acceleration in collisionless shocks. Probing such extreme scenarios in the laboratory is still an open challenge. In this work, we investigate the possibility of using neutral e−e^{-} e+e^{+} beams to explore the CFI with realistic parameters, by performing 2D particle-in-cell simulations. We show that CFI can occur unless the rate at which the beam expands due to finite beam emittance is larger than the CFI growth rate and as long as the role of competing electrostatic two-stream instability (TSI) is negligible. We also show that the longitudinal energy spread, typical of plasma based accelerated electron-positron fireball beams, plays a minor role in the growth of CFI in these scenarios
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