Search results for "Relativity"
showing 10 items of 1213 documents
Relativistic Positioning Systems in Flat Space-Time: The Location Problem
2013
The location problem in relativistic positioning is considered in flat space-time. When two formal solutions are possible for a user (receiver) of the system, its true location may be obtained from a standard set of emission data extended with an observational rule. The covariant expression giving the location of the user in inertial coordinates is decomposed with respect to an inertial observer.
Why you trust in visual saliency
2015
Image understanding is a simple task for a human observer. Visual attention is automatically pointed to interesting regions by a natural objective stimulus in a first step and by prior knowledge in a second step. Saliency maps try to simulate human response and use actual eye-movements measurements as ground truth. An interesting question is: how much corruption in a digital image can affect saliency detection respect to the original image? One of the contributions of this work is to compare the performances of standard approaches with respect to different type of image corruptions and different threshold values on saliency maps. If the corruption can be estimated and/or the threshold is fi…
Hochschild Cohomology Theories in White Noise Analysis
2008
We show that the continuous Hochschild cohomology and the differential Hochschild cohomology of the Hida test algebra endowed with the normalized Wick product are the same.
Radiative 2D Shocks, Super-Eddington Disks and Jets around Black Holes
2005
It is well known that rotating inviscid accretion flows with adequate injection parameters around black holes could form shock waves close to the black holes, after the flow passes through the outer sonic point and can be virtually stopped by the centrifugal force. Such shock waves in 2D accretion flows are examined by 2D radiation hydrodynamical calculations. We also examine super‐Eddington accretion disks with 15 ṀE around black holes, focusing on a small collimation degree of the jet and a large mass‐outflow rate observed in the X‐ray source SS 433.
Radio mode feedback: Does relativity matter?
2017
Radio mode feedback, associated with the propagation of powerful outflows in active galaxies, is a crucial ingredient in galaxy evolution. Extragalactic jets are well collimated and relativistic, both in terms of thermodynamics and kinematics. They generate strong shocks in the ambient medium, associated with observed hotspots, and carve cavities that are filled with the shocked jet flow. In this Letter, we compare the pressure evolution in the hotspot and the cavity generated by relativistic and classical jets. Our results show that the classical approach underestimates the cavity pressure by a factor larger or equal to 2 for a given shocked volume during the whole active phase. The tensio…
Practical formula for the evaluation of high-order multiphoton absorption in thin nonlinear media
2009
We present an analytical formula for the fast and accurate evaluation of nonlinear absorption in materials exhibiting an admixture of different multiphoton processes. This approach is specifically addressed for its use in thin films when the slowly varying envelope approximation applies. The contribution of absorptions of distinct order is conveniently averaged in order to use well-known expressions for a single multiphoton process. In the latter case, therefore, our simple expression is reduced toward the exact solution.
Facing natural disasters through the endorsement of authoritarian attitudes
2020
Abstract We analyzed the relations between exposure to news describing a natural disaster and right-wing authoritarianism (RWA) with 241 Italian adults, surveyed twice, before and after a severe earthquake. Our results were compatible with the idea that the exposure to earthquake news led to an increase in RWA among people who had low, but not among who had relatively high, authoritarian levels before the event. We discuss the findings in terms of compensatory control, and highlight strengths and limitations of the study.
It's the Debates, Stupid! How the Introduction of Televised Debates Changed the Portrayal of Chancellor Candidates in the German Press, 1949—2005
2007
Media election campaign coverage is said to have changed fundamentally in recent decades. Among the trends identified are personalization, negativism, more interpretive coverage, deauthentication, and horse-race coverage. Usually, U.S. studies are cited as empirical evidence for these developments. Recent studies of European campaigns have shown, however, that the picture seems to be different there in various respects.This article argues that one of the reasons for the differences might be the lack of some central campaign events in European elections. Taking Germany as an example, it investigates how the introduction of American-style televised debates in 2002 and 2005 changed media cove…
A "imunidade soberana" de Pinochet contestada
2000
Um observador privilegiado e participante do processo que levou à quebra da "imunidade soberana" do ex-ditador chileno Augusto Pinochet expõe como e em nome do que isso ocorreu. A privileged observer of, as well as a participant in, the process that resulted in the breaking of the "sovereign immunity" of Chiles former dictator Augusto Pinochet tells how and in the name of what this happened.
Coxeter on People and Polytopes
2004
H. S. M. Coxeter, known to his friends as Donald, was not only a remarkable mathematician. He also enriched our historical understanding of how classical geometry helped inspire what has sometimes been called the nineteenth-century’s non-Euclidean revolution (Fig. 35.1). Coxeter was no revolutionary, and the non-Euclidean revolution was already part of history by the time he arrived on the scene. What he did experience was the dramatic aftershock in physics. Countless popular and semi-popular books were written during the early 1920s expounding the new theory of space and time propounded in Einstein’s general theory of relativity. General relativity and subsequent efforts to unite gravitati…