X-ray polarimetric signatures induced by spectral variability in the framework of the receding torus model

Obscuring circumnuclear dust is a well-established constituent of active galactic nuclei (AGN). Traditionally referred to as the receding dusty torus, its inner radius and angular extension should depend on the photo-ionizing luminosity of the central source. Using a Monte Carlo approach, we simulate the radiative transfer between the multiple components of an AGN adopting model constraints from the bright Seyfert galaxy NGC 4151. We compare our model results to the observed near-IR to UV polarization of the source and predict its X-ray polarization. We find that the 2-8 keV polarization fraction of a standard AGN model varies from less then a few percent along polar viewing angles up to tens of percent at equatorial inclinations. At viewing angles around the type-1/type-2 transition the X-ray polarization variability differs between a static or a receding torus scenario. In the former case, the expected 2-8 keV polarization of NGC 4151 is found to be 1.21% +/- 0.34% with a constant polarization position angle, while in the later scenario it varies from 0.1% to 6% depending on the photon index of the primary radiation. Additionally, an orthogonal rotation of the polarization position angle with photon energy appears for very soft primary spectra. Future X-ray polarimetry missions will be able to test if the receding model is valid for Seyfert galaxies seen at a viewing angle close to the torus horizon. The overall stability of the polarization position angle for photon indexes softer than {\Gamma} = 1.5 ensures that reliable measurements of X-ray polarization are possible. We derive a long-term observational strategy for NGC 4151 assuming observations with a small to medium-size X-ray polarimetry satellite.Comment: 10 pages, 8 Figures, accepted for publication in A&

Power in the Multinational Corporation in Industry Equilibrium

Recent theories of the multinational corporation introduce the property rights model of the firm and examine whether to integrate our outsource firm activities locally or to a foreign country. This paper focus instead on the internal organization of the multinational corporation by examining the power allocation between headquarters and subsidiaries. We provide a framework to analyse the interaction between the decision to serve the local market by exporting or FDI, market acces and the optimal mode of organization of the multinational corporation. We find that subsidiary managers are given most autonomy in their decision how to run the firm at intermediate levels of local competition. We then provide comparative statics for changes in fixed FDI entry costs and trade costs, information technology, the number of local competitors, and in the size of the local market

Corporate Hierarchies and the Size of Nations: Theory and Evidence

Corporate organization varies within a country and across countries with country size. The paper starts by establishing some facts about corporate organization based on unique data of 660 Austrian and German corporations. The larger country (Germany) has larger firms with flatter more decentral corporate hierarchies compared to the smaller country (Austria). Firms in the larger country change their organization less fast than firms in the smaller country. Over time firms have been introducing less hierarchical organizations by delegating power to lower levels of the corporation. We develop a theory which explains these facts and which links these features to the trade environment that countries and firms face. We introduce firms with internal hierarchies in a Krugman (1980) model of trade. We show that international trade and the toughness of competition in international markets induce a power struggle in firms which eventually leads to decentralized corporate hierarchies. We offer econometric evidence which is consistent with the models predictions

Wayward Nosh

Design Challenge How do you get 4-8 year olds to understand their food allergy well enough to communicate it to others? When parents learn their child has a food allergy, for them, it is a stressful, life-changing discovery. For the child, this knowledge has no meaning, yet. Here, there is the opportunity to break down connotations associated with allergies. Through design intervention, this book explores the possibilities of transforming food from problems into assets. For instance, Superman might be “allergic” to kryptonite, but he also has superpowers. Rather than label the child with allergies, why not rebrand allergies to turn a perceived negative circumstance into a relatively positive one? There is a moment when a child with food allergies needs to leave their parent’s side for the first time to go to kindergarten. They are plunged into a world of rules and expectations. That alone can be overwhelming for a developing mind, but to add the challenge of having a food allergy on top of it all makes this day all the more intense. The project looks to redesign the overall food allergy experience for both children and their parents, from the moment a parent has that life-changing conversation with their child to when the child is eating lunch at school everyday with their peers. Research for this project was a combination of listening the stories of those people affected by food allergies, gathering literature on the topic of food allergies, market research, and reaching out to professionals with insight into various related topics, such as teachers, librarians, and doctors. The design process was a cycle of sketching, creating, testing, analyzing, refining, and repeat. The idea of having a system of objects that work together to reinforce a narrative began in early design stages. The design process then became about developing a character to use as a vehicle for communicating to children. Wolfelopes are fictional creatures, part wolf, part antelope, designed specifically for this project. In the end, the final prototypes included a children’s book, The Wolfelopes: An Allergy Adventure, a character-based lunch box, and packaging. Each object addresses different design goals, but when they come together, an larger story is created. The collection of objects work together to rewrite the experience children and parents have of learning about and coping with food allergies. The Wolfelopes, the book is meant to be used as a tool by parents to help introduce food allergies to their child. The book can then be brought to show-and-tell and shared with the class. This will help the child with food allergies learn to communicate their allergy to their teachers and peers. While the wolfelope lunch box functions as a toy for the child, it is also a physical representation of a parent’s effort to prepare their child for the world. Further the lunch box signals to carers (i.e. teachers) which students might have food allergies. Since the design works to associate these characters with food allergies, the child will subtly adopt the habit of being conscious of their food allergy during meal times. The book and the lunch box are packaged in a box that, when opened, becomes a toy tray and a poster. The intention of having the revelation of the dominant objects be a process reminiscent of receiving a present is to attach positive connotations to The Wolfelope Kit. In conclusion, these objects each play a role in empowering children with food allergies by turning a perceived flaw into an asset

Dileptons from the nonequilibrium Quark-Gluon Plasma

According to the dynamical quasiparticle model (DQPM) -- matched to reproduce lattice QCD results in thermodynamic limit, -- the constituents of the strongly interacting quark-gluon plasma (sQGP) are massive and off-shell quasi-particles (quarks and gluons) with broad spectral functions. In order to address the electromagnetic radiation of the sQGP, we derive off-shell cross sections of $q\bar q\to\gamma^*$, $q\bar q\to\gamma^*+g$ and $qg\to\gamma^*q$($\bar q g\to\gamma^* \bar q$) reactions taking into account the effective propagators for quarks and gluons from the DQPM. Dilepton production in In+In collisions at 158 AGeV is studied by implementing these processes into the parton-hadron-string dynamics (PHSD) transport approach. The microscopic PHSD transport approach describes the full evolution of the heavy-ion collision: from the dynamics of quasi-particles in the sQGP phase (when the local energy density is above $\sim 1$ GeV/fm$^3$) through hadronization and to the following hadron interactions and off-shell propagation after the hadronization. A comparison to the data of the NA60 Collaboration shows that the low mass dilepton spectra are well described by including a collisional broadening of vector mesons, while the spectra in the intermediate mass range are dominated by off-shell quark-antiquark annihilation, quark Bremsstrahlung and gluon-Compton scattering in the nonperturbative QGP. In particular, the observed softening of the $m_T$ spectra at intermediate masses (1 GeV $\le M \le$ 3 GeV) is approximately reproduced.Comment: 8 pages, 8 figures, to be published in the Proceedings of the 26th Winter Workshop on `Nuclear Dynamics', Ochto Rios, Jamaica, 2-9 January, 201

Lease-based Decentralized Resource Management in Open Multi-Agent Systems

A distributed management architecture is proposed for Internet-scale, open, distributed agent middleware systems. The management architecture presented supports the autonomy of both agents and middleware resources, incorporating an agent-initiated contract negotiation model for resource allocation and access. A leasing mechanism infrastructure designed and implemented for this purpose is presented

Higher education students’ media usage: A longitudinal analysis

Responding to the lack of longitudinal analyses on media usage in higher education, this study explores the changes of higher education students’ access to and use of technology for learning in 2012, 2015 and 2018. Using an online questionnaire, a total of 5,572 German higher education students participated. Via descriptive and inferential analysis, the data show a clear trend towards using flexible, location-independent devices, accompanied by a rapid increase in the use of instant messaging. This is in line with an increasing demand for digital and flexible learning opportunities such as web-based training and lectures as podcasts or vodcasts, which is not met by higher education institutions. On that basis, improvements in development and application of these digital tools seem crucial for German higher education institutions and should be considered by educational technologists and decision makers. Of particular relevance against the background of the COVID-19 pandemic that started in Spring 2020, this longitudinal analysis provides a framework for the ongoing development and implementation of digital media in teaching and learning at higher education institutions