Limits of Thompson's group F

Let F be the Thompson's group. We study the structure of F-limit groups. Consider a sequence of groups marked by three elements, each isomorphic to F. Assume that the this sequence is convergent in the space of marked groups. We prove that no HNN-extension of F over a cyclic subgroup occurs as an F-limit group of such a sequence.Comment: 11 page

Urban Games: Convergence of physical and virtual

Redefining the city as interactive media can reveal new possibilities for architects and designers. Today, designers must augment architecture and urbanism by incorporating new aspects of virtual habitation. This paper investigates contemporary attitudes toward digital public spaces, from media facades, augmented reality games, and mobile apps to guerrilla-like techniques such as tactical media, activist gaming, and electronic civil disobedience. It looks at these notions as renewed forms of public participation that build upon the past analog models. It touches on the relationship between ownership and authorship of the public realm, and the role design, art, and technology play in this balance. Ubiquitous technologies, democratization of access to and means of creative production, and virtualization of physicality allow for broader participation in cultural authorship and ownership, an opportunity that may not be fully realized if not embraced effectively. In this redefined image of the city, online and mobile games become important contributor to genius loci and emerging social networks. Furthermore, this paper discusses the mutually-informing relationship between the imaginary (virtual) and the real (physical). It presents the city as a virtual construct modulated by pervasive and ubiquitous computing, social networking, and (geo)location-based participatory events such as augmented reality (AR) gaming. In the perceptual dimension, video games, such as Grand Auto Theft, Mirror's Edge, or Assassins' Creed, are becoming potent advocates or adversaries of traditional image (notion) of the city. The combination of purely virtual reality (VR) game cities and augmented reality (AR), information-laced and geo-located environments transforms our expectations towards urban landscapes. This paper investigates the following aspects of augmented urbanisms: the virtual city of computer games and movie narratives, the physical city overlaid with virtual information accessible via augmented reality browsers and electronic social networks. It also looks into how these new electronic agents facilitate an unconventional use of the city

Forecasted attribution of the human influence on Hurricane Florence.

Changes in extreme weather, such as tropical cyclones, are one of the most serious ways society experiences the impact of climate change. Advance forecasted conditional attribution statements, using a numerical model, were made about the anthropogenic climate change influence on an individual tropical cyclone, Hurricane Florence. Mean total overland rainfall amounts associated with the forecasted storm's core were increased by 4.9 ± 4.6% with local maximum amounts experiencing increases of 3.8 ± 5.7% due to climate change. A slight increase in the forecasted storm size of 1 to 2% was also attributed. This work reviews our forecasted attribution statement with the benefit of hindsight, demonstrating credibility of advance attribution statements for tropical cyclones

Chemical order and crystallographic texture of FePd:Cu thin alloy films

FePd thin films have been recently considered as promising material for high-density magnetic storage devices. However, it is necessary to find a proper method of fabrication for the (001)-textured and chemically well-ordered alloy. In this paper, we present the detailed investigations of lattice parameters, chemical order degree, grain sizes and crystallographic texture, carried out on FePd alloys with 10 at.% of Cu addition. The initial [Cu(0.2 nm)/Fe(0.9 nm)/Pd(1.1 nm)]x5 multilayers were thermally evaporated in an ultra-high vacuum on MgO(100), Si(100), Si(111) and Si(100) covered by 100 nm thick layer of amorphous SiO2. In order to obtain homogeneous FePd:Cu alloy, the multilayers were annealed in two different ways. First, the samples were rapidly annealed in nitrogen atmosphere at 600oC for 90 seconds. Next, the long annealing in a high vacuum for 1 hour at 700oC was done. This paper focuses on quantitative investigations of the chemical order degree and crystallographic texture of ternary FePd:Cu alloys deposited on four different substrates. In order to obtain both quantities we have taken a novel approach to consider the problem of dopant atoms located in the FePd structure. The studies of the structure were done using X-Ray Diffraction (XRD) performed with synchrotron radiation and pole figures measurements. We have found that the addition of Cu changes the FePd lattice parameters and lattice distortion. We have also shown, that using different substrates it is possible to obtain a FePd:Cu alloy with different chemical order and texture. Moreover, it was observed that texture category is substrate dependent

Exchange Bias in the [CoO/Co/Pd]10 Antidot Large Area Arrays

Magnetic nanostructures revealing exchange bias effect have gained a lot of interest in recent years due to their possible applications in modern devices with various functionalities. In this paper, we present our studies on patterned [CoO/Co/Pd]10 multilayer where ferromagnetic material is in a form of clusters, instead of being a continuous layer. The system was patterned using nanosphere lithography technique which resulted in creation of an assembly of well-ordered antidots or islands over a large substrate area. We found that the overall hysteresis loop of the films consists of hard and soft components. The hard component hysteresis loop exhibits a large exchange bias field up to -11 kOe. The patterning process causes a slight increase of the exchange field as the antidot radius rises. We also found that the material on edges of the structures gives rise to a soft unbiased magnetization component.Comment: 5 figure