974 resultados para free eletromagnetic field


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Nick Dyer-Witheford’s Cyber-Marx was published nearly 15 years ago, but there are continuing echoes of its dire promises today. The trends that Dyer-Witheford outlined—the growth of tech-giants in the communications field at the expense of democratic media practices and the radical shedding of jobs in the traditional mass media context—are confirmed by recent events. In November 2013, Twitter launched itself on the public share register, despite having no visible means of financial support, or even much of a business plan. The Twitter IPO tells us a lot about the economy of cyber-capitalism. Aligned to the trend of ‘technological unemployment’ is the rise of what some commentators call ‘digital serfdom’. This is not just growing unemployment, but also drastic under-employment of talented media professionals and an alarming rise in the number of media outlets that want to pay contributors in ‘exposure’, rather than in corporeal, fungible dollars and cents. This articlediscusses these trends and events in the context of the political economy of digital communication.

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An understanding of koala activity patterns is important for measuring the behavioral response of this species to environmental change, but to date has been limited by the logistical challenges of traditional field methodologies. We addressed this knowledge gap by using tri-axial accelerometer data loggers attached to VHF radio collars to examine activity patterns of adult male and female koalas in a high-density population at Cape Otway, Victoria, Australia. Data were obtained from 27 adult koalas over two 7-d periods during the breeding season: 12 in the early-breeding season in November 2010, and 15 in the late-breeding season in January 2011. Multiple 15 minute observation blocks on each animal were used for validation of activity patterns determined from the accelerometer data loggers. Accelerometry was effective in distinguishing between inactive (sleeping, resting) and active (grooming, feeding and moving) behaviors. Koalas were more active during the early-breeding season with a higher index of movement (overall dynamic body acceleration [ODBA]) for both males and females. Koalas showed a distinct temporal pattern of behavior, with most activity occurring from mid-afternoon to early morning. Accelerometry has potential for examining fine-scale behavior of a wide range of arboreal and terrestrial species.

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A novel solution spinning method to produce highly conducting carbon nanotube (CNT) biofibers is reported. In this process, carbon nanotubes are dispersed using biomolecules such as hyaluronic acid, chitosan, and DNA, and these dispersions are used as spinning solutions. Unlike previous reports in which a polymer binder is used in the coagulation bath, these dispersions can be converted into fibers simply by altering the nature of the coagulation bath via pH control, use of a crosslinking agent, or use of a biomolecule-precipitating solvent system. With strength comparable to most reported CNT fibers to date, these CNT biofibers demonstrate superior electrical conductivities. Cell culture experiments are performed to investigate the cytotoxicity of these fibers. This novel fiber spinning approach could simplify methodologies for creating electrically conducting and biocompatible platforms for a variety of biomedical applications, particularly in those systems where the application of an electrical field is advantageous?for example, in directed nerve and/or muscle repair.

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Three significant events at the start of 2015 have put freedom of speech firmly on the global agenda. The first was the carry-over from the December 2014 illegal entry to the Sony Corporation’s file servers by anonymous hackers, believed to be linked to the North Korean regime. The second was the horrible attack on journalists, editors, and cartoonists at the French satirical magazine, Charlie Hebdo on 7 January. The third was the election of leftwing anti-austerity party Syrzia in Greece on 25 January.While each event is different in scope and size, they are important to scholars of the political economy of communication because they all speak to ongoing debates about freedom of expression, freedom of speech and freedom of the press. I name each of these concepts separately because, despite popular confusion, they are not the same thing (Patching and Hirst, 2014) . Freedom of expression is the right to individual self-expression through any means; it is an inalienable human right. Freedom of speech refers to the right (and the physical ability) to utter political speech, to say what others wish to repress and to demand a voice with which to express a range of social and political thoughts. Freedom of the press is a very particular version of freedom of expression that is intimately bound with the political economy of speech and of the printing press. Freedom of the press is impossible without the press and, despite its theoretical availability to all of us, this principle is impossible to articulate without the material means (usually money) to actually deploy a printing press (or the electronic means of broadcasting and publishing).Freedom of expression is immutable; freedom of speech subject to legal, ethical and ideological restriction (for better, or worse) and freedom of the press is peculiar to bourgeois society in that it entails the freedom to own and operate a press, not the right to say or publish on a level playing field. Access to freedom of the press is determined in the marketplace and is subject to the unequal power relationships that such determination implies.It is fitting to start with the Charlie Hebdo massacre because the loss of 17 lives makes this the most chilling of the three events and demands that it be given prominence in any analysis. No lives have been lost yet because Sony’s computers were hacked and the election of Syriza has not (yet) led to mass deaths in Greece.

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This study investigated prey captures in free-ranging adult female Australian fur seals (Arctocephalus pusillus doriferus) using head-mounted 3-axis accelerometers and animal-borne video cameras. Acceleration data was used to identify individual attempted prey captures (APC), and video data were used to independently verify APC and prey types. Results demonstrated that head-mounted accelerometers could detect individual APC but were unable to distinguish among prey types (fish, cephalopod, stingray) or between successful captures and unsuccessful capture attempts. Mean detection rate (true positive rate) on individual animals in the testing subset ranged from 67-100%, and mean detection on the testing subset averaged across 4 animals ranged from 82-97%. Mean False positive (FP) rate ranged from 15-67% individually in the testing subset, and 26-59% averaged across 4 animals. Surge and sway had significantly greater detection rates, but also conversely greater FP rates compared to heave. Video data also indicated that some head movements recorded by the accelerometers were unrelated to APC and that a peak in acceleration variance did not always equate to an individual prey item. The results of the present study indicate that head-mounted accelerometers provide a complementary tool for investigating foraging behaviour in pinnipeds, but that detection and FP correction factors need to be applied for reliable field application.

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The ways in which Internet traffic is managed have direct consequences on Internet users’ rights as well as on their capability to compete on a level playing field. Network neutrality mandates to treat Internet traffic in a non-discriminatory fashion in order to maximise end users’ freedom and safeguard an open Internet. This book is the result of a collective work aimed at providing deeper insight into what is network neutrality, how does it relates to human rights and free competition and how to properly frame this key issue through sustainable policies and regulations. The Net Neutrality Compendium stems from three years of discussions nurtured by the members of the Dynamic Coalition on Network Neutrality (DCNN), an open and multistakeholder group, established under the aegis of the United Nations Internet Governance Forum (IGF).

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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We explore here the issue of duality versus spectrum equivalence in dual theories generated through the master action approach. Specifically we examine a generalized self-dual (GSD) model where a Maxwell term is added to the self-dual model. A gauge embedding procedure applied to the GSD model leads to a Maxwell-Chern-Simons (MCS) theory with higher derivatives. We show here that the latter contains a ghost mode contrary to the original GSD model. By figuring out the origin of the ghost we are able to suggest a new master action which interpolates between the local GSD model and a nonlocal MCS model. Those models share the same spectrum and are ghost free. Furthermore, there is a dual map between both theories at classical level which survives quantum correlation functions up to contact terms. The remarks made here may be relevant for other applications of the master action approach.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This paper describes an interactive environment built entirely upon public domain or free software, intended to be used as the preprocessor of a finite element package for the simulation of three-dimensional electromagnetic problems.

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Using the axially-symmetric time-dependent Gross-Pitaevskii equation we study the phase coherence in a repulsive Bose-Einstein condensate (BEC) trapped by a harmonic and an one-dimensional optical lattice potential to describe the experiment by Cataliotti et al. on atomic Josephson oscillation [Science 293, 843 (2001)]. The phase coherence is maintained after the BEC is set into oscillation by a small displacement of the magnetic trap along the optical lattice. The phase coherence in the presence of oscillating neutral current across an array of Josephson junctions manifests in an interference pattern formed upon free expansion of the BEC. The numerical response of the system to a large displacement of the magnetic trap is a classical transition from a coherent superfluid to an insulator regime and a subsequent destruction of the interference pattern in agreement With the more recent experiment by Cataliotti et al. [New J. Phys. 5, 71 (2003)].

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We use a time-dependent dynamical mean-field-hydrodynamic model to study the formation of fermionic dark solitons in a trapped degenerate Fermi gas mixed with a Bose-Einstein condensate in a harmonic as well as a periodic optical-lattice potential. The dark soliton with a 'notch' in the probability density with a zero at the minimum is simulated numerically as a nonlinear continuation of the first vibrational excitation of the linear mean-field-hydrodynamic equations, as suggested recently for pure bosons. We study the free expansion of these dark solitons as well as the consequent increase in the size of their central notch and discuss the possibility of experimental observation of the notch after free expansion.