A Macromodeling-Based Hybrid Method for the Computation of Transient Electromagnetic Fields Scattered by Nonlinearly Loaded Metal Structures

In this article, we present a hybrid numerical scheme to compute the transient electromagnetic fields scattered by a metallic structure loaded with lumped nonlinear loads. The proposed scheme is based on three successive steps. First, the field coupling problem to the structure with the nonlinear loads removed is solved in the frequency domain using a method-of-moments (MoM) formulation. The unloaded structure is thus characterized as a generalized multiport Thevenin equivalent, whose components are represented as time-domain operators by performing a set of rational approximations followed by closed-form Laplace transform inversion. Transient port voltages and currents in the presence of nonlinear loads are then computed using a standard circuit solver. As a last step, the substitution theorem is used to solve the radiation problem again in the frequency domain using a MoM solver, the results of which are then translated into the time domain by means of rational approximations and recursive convolution operations. The proposed method enables an accurate and efficient evaluation of the transient nonlinearly scattered fields by the loaded structure, with a good potential for scalability to large-scale high-complexity nonlinear shields. Extensive validations are provided to demonstrate the accuracy of the proposed method, which is here applied to the characterization of energy-selective shielding for protection of sensitive devices from high-intensity radiated fields

Quickest Paths in Simulations of Pedestrians

This contribution proposes a method to make agents in a microscopic simulation of pedestrian traffic walk approximately along a path of estimated minimal remaining travel time to their destination. Usually models of pedestrian dynamics are (implicitly) built on the assumption that pedestrians walk along the shortest path. Model elements formulated to make pedestrians locally avoid collisions and intrusion into personal space do not produce motion on quickest paths. Therefore a special model element is needed, if one wants to model and simulate pedestrians for whom travel time matters most (e.g. travelers in a station hall who are late for a train). Here such a model element is proposed, discussed and used within the Social Force Model.Comment: revised version submitte

Reconstructing Deconstruction: High-Velocity Cloud Distance Through Disruption Morphology

We present Arecibo L-band Feed Array 21-cm observations of a sub-complex of HVCs at the tip of the Anti-Center Complex. These observations show morphological details that point to interaction with the ambient halo medium and differential drag within the cloud sub-complex. We develop a new technique for measuring cloud distances, which relies upon these observed morphological and kinematic characteristics, and show that it is consistent with H-alpha distances. These results are consistent with distances to HVCs and halo densities derived from models in which HVCs are formed from cooling halo gas.Comment: 8 pages, 2 figures, 1 tabe, Accepted to Ap

High Velocity Cloud Complex H: A Satellite of the Milky Way in a Retrograde Orbit?

Observations with the Green Bank Telescope of 21cm HI emission from the high-velocity cloud Complex H suggest that it is interacting with the Milky Way. A model in which the cloud is a satellite of the Galaxy in an inclined, retrograde circular orbit reproduces both the cloud's average velocity and its velocity gradient with latitude. The model places Complex H at approximately 33 kpc from the Galactic Center on a retrograde orbit inclined about 45 degrees to the Galactic plane. At this location it has an HI mass > 6 10^6 Msun and dimensions of at least 10 by 5 kpc. Some of the diffuse HI associated with the cloud has apparently been decelerated by interaction with Galactic gas. Complex H has similarities to the dwarf irregular galaxy Leo A and to some compact high-velocity clouds, and has an internal structure nearly identical to parts of the Magellanic Stream, with a pressure P/k about 100 cm^{-3} K.Comment: 12 pages includes 4 figures. To be published in Astrophysical Journal Letters, 1 July 200

Political hashtag publics and counter-visuality: a case study of #fertilityday in Italy

In 2016 the Italian health ministry launched the ‘Fertility Day’ campaign, aimed at tackling Italy’s low birth rate. Under the accusation of delivering sexist and racist messages, the campaign became a trending topic on Twitter, and a protest was launched to be held during Fertility Day. By applying a combination of digital methods and visual content analysis to the #fertilityday Twitter stream, this paper contributes to existing research on the deliberative strength of political hashtag publics, with a particular focus on their power structures, communication patterns and visual content use. Findings on gatekeeping dynamics downsize optimistic views on the democratising potential of Twitter’s socio-technical infrastructure as they point to the emergence of online satirical media and ‘tweetstars’ – along with mainstream news media– as main producers of spreadable content, with ordinary users only surfacing when traditional media elites and new satirical actors lack or lose interest in the debate. Results confirm that political hashtag publics follow acute event communication patterns, with users highly engaged in retweeting and referencing external material and visual content playing a key role in these gatewatching practices. The transient counter-visuality – or critical stance – of tweets with user-manipulated images, however, also suggests that the deliberative potential of these publics is not easily sustainable over time

HIV Activates the Tyrosine Kinase Hck to Secrete ADAM Protease-Containing Extracellular Vesicles

HIV-Nef activates the myeloid cell-typical tyrosine kinase Hck, but its molecular role in the viral life cycle is not entirely understood. We found that HIV plasma extracellular vesicles (HIV pEV) containing/10 proteases and Nef also harbor Hck, and analyzed its role in the context of HIV pEV secretion. Myeloid cells required Hck for the vesicle-associated release of ADAM17. This could be induced by the introduction of Nef and implied that HIV targeted Hck for vesicle-associated ADAM17 secretion from a myeloid compartment. The other contents of HIV-pEV, however, including miRNA and effector protein profiles, as well as the presence of haptoglobin suggested hepatocytes as a possible cellular source. HIV liver tissue analysis supported this assumption, revealing induction of Hck translation, evidence for ADAMprotease activation and HIV infection. Our findings suggest that HIV targets Hck to induce pro-inflammatory vesicles release and identifies hepatocytes as a possible host cell compartment. (c) 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.Peer reviewe