A comparison of different trading protocols in an agent-based market

We compare price dynamics of different market protocols (batch auction, continuous double auction and dealership) in an agent-based artificial exchange. In order to distinguish the effects of market architectures alone, we use a controlled environment where allocative and informational issues are neglected and agents do not optimize or learn. Hence, we rule out the possibility that the behaviour of traders drives the price dynamics. Aiming to compare price stability and execution quality in broad sense, we analyze standard deviation, excess kurtosis, tail exponent of returns, volume, perceived gain by traders and bid-ask spread. Overall, a dealership market appears to be the best candidate in this respect, generating low volume and volatility, virtually no excess kurtosis and high perceived gain.Artificial markets, Agent-based models, Microstructural architectures

Exciton lasing in carbon nanotubes below the population inversion threshold via phonon-mediated stimulated emission

Excitonic optical transitions in carbon nanotubes (CNTs) have been extensively studied for at least two decades. However, exploiting these transitions to produce a lasing effect has been proved unpractical due to the difficulties of achieving an excitonic population inversion in carbon nanotubes. In this work we show that lasing is theoretically possible at a much lower exciton population threshold by taking advantage of phonon stimulated emission. Specifically, the so-called Anti-Stokes transitions, where light is generated by the creation of a phonon and the annihilation of an exciton, can be used to sustain the coherent emission of photons. These transitions have been overlooked for long due to their low intensity as a consequence of the low occupancy of the associated phonon branches. We show that the best conditions to achieve the lasing effect are met in CNTs with i) excitons of non-zero momentum, ii) a strong exciton-phonon coupling and iii) narrow exciton transitions

Electron-phonon coupling and hot electron thermalization in titanium nitride

We have studied the thermalization of hot carriers in both pristine and defective titanium nitride (TiN) using a two-temperature model. All parameters of this model, including the electron-phonon coupling parameter, were obtained from rst-principles density-functional theory calculations. The virtual crystal approximation was used to describe defective systems. We nd that thermalization of hot carriers occurs on much faster time scales than in gold as a consequence of the signi cantly stronger electronphonon coupling in TiN. Speci cally, the largest thermalization times, on the order of 200 femtoseconds, are found in TiN with nitrogen vacancies for electron temperatures around 4000 K

O MOVIMENTO COMO MODO DE CRIAÇÃO: A EXPERIÊNCIA DO VIVO

Este estudo observa aspectos do sistema proposto por Konstantin Stanislávski referentes aos processos de vivência corporificada das ações físicas. Os elementos do sistema atenção, tempo-ritmo, imaginação e plasticidade dos movimentos são apresentados como operadores dos impulsos que efetivam o movimento em ato, e este como produto e produção de vivência, a experiência do vivo. Nesse sentido, os movimentos são portadores de intensidade e de tendências para a tessitura do acontecimento cênico

Discutindo as potencialidades dos vídeos tutoriais para a utilização em educação a distância

It is observed that teachers, in general, use of a limited available resources in the virtual learning environment (VLE) and others external to it which could be inserted in this expanding training opportunities offered both classroom teaching, as distance education. Thus, this paper aims to present the process of construction of tutorial videos and discuss its use in educational activities in different educational modalities. For this study, we used, at first, a literature about the main issues involved in the production and use of video tutorials. To understand and promote the use tutorial videos as educational resources for teachers of university teaching, distance education and classroom teaching, broke for creating some videos. The process of creating a video tutorial involves different steps and specific knowledge, especially concerning the characteristics and potentials of different softwares.Observa-se que os professores, de modo geral, utilizam de forma limitada os recursos disponíveis no ambiente virtual de aprendizagem (AVA) e também outros externos a ele que poderiam ser inseridos neste ampliando as possibilidades formativas oferecidas tanto do ensino presencial, quanto da educação a distância. Assim, este artigo tem como objetivo apresentar o processo de construção de vídeos tutoriais e discutir a sua utilização em atividades pedagógicas nas diferentes modalidades educativas. Para realização deste trabalho, utilizou-se, num primeiro momento, de pesquisa bibliográfica a respeito dos principais assuntos envolvidos na produção e uso dos vídeos tutoriais. Para compreender e fomentar o uso vídeos tutoriais como recursos educacionais por professores de ensino superior, na educação a distância e no ensino presencial, partiu-se para a criação de alguns vídeos. O processo de criação de um vídeo tutorial envolve diferentes etapas e conhecimentos específicos, sobretudo quanto às características e potencialidades de diferentes softwares