Orbital Magnetism in Ensembles of Parabolic Potentials

We study the magnetic susceptibility of an ensemble of non-interacting electrons confined by parabolic potentials and subjected to a perpendicular magnetic field at finite temperatures. We show that the behavior of the average susceptibility is qualitatively different from that of billiards. When averaged over the Fermi energy the susceptibility exhibits a large paramagnetic response only at certain special field values, corresponding to comensurate classical frequencies, being negligible elsewhere. We derive approximate analytical formulae for the susceptibility and compare the results with numerical calculations.Comment: 4 pages, 4 figures, REVTE

The Offline Software Framework of the Pierre Auger Observatory

The Pierre Auger Observatory is designed to unveil the nature and the origins of the highest energy cosmic rays. The large and geographically dispersed collaboration of physicists and the wide-ranging collection of simulation and reconstruction tasks pose some special challenges for the offline analysis software. We have designed and implemented a general purpose framework which allows collaborators to contribute algorithms and sequencing instructions to build up the variety of applications they require. The framework includes machinery to manage these user codes, to organize the abundance of user-contributed configuration files, to facilitate multi-format file handling, and to provide access to event and time-dependent detector information which can reside in various data sources. A number of utilities are also provided, including a novel geometry package which allows manipulation of abstract geometrical objects independent of coordinate system choice. The framework is implemented in C++, and takes advantage of object oriented design and common open source tools, while keeping the user side simple enough for C++ novices to learn in a reasonable time. The distribution system incorporates unit and acceptance testing in order to support rapid development of both the core framework and contributed user code.Comment: 4 pages, 2 figures, presented at IEEE NSS/MIC, 23-29 October 2005, Puerto Ric

Superscars in the LiNC=LiCN isomerization reaction

We demonstrate the existence of superscarring in the LiNC=LiCN isomerization reaction described by a realistic potential interaction in the range of readily attainable experimental energies. This phenomenon arises as the effect of two periodic orbits appearing "out of the blue"in a saddle--node bifurcation taking place in the dynamics of the system. Potential practical consequences of this superlocalization in the corresponding wave functions are also considered.Comment: 6 pages, 5 figures. to appear in EP

Eficiência agronômica de fontes de fósforo associadas à inoculação com Pseudomonas fluorescens na produtividade de grãos do milho.

Visando a melhor eficiência agronômica relativa (EAR) do uso dos fertilizantes fosfatados, este estudo teve como objetivo avaliar o efeito de fontes de P associados à inoculação com Pseudomonas fluorescens via sementes na produtividade de grãos de plantas de milho. O experimento foi conduzido a campo, em esquema fatorial 6x2, em blocos casualizados, com quatro repetições. Foram aplicados 120 kg ha-1 de P via solo por meio de cinco fontes: Superfosfato Triplo (SFT), Gafsa, Itafós, SFT+Gafsa e SFT+Itafós, além do controle (sem P). As sementes foram submetidas a dois níveis de inoculação (com e sem) com Pseudomonas fluorescens da Estirpe 1008. Realizou-se a avaliação da EAR da produtividade de grãos. A inoculação de P. fluorescens no controle resultou em 87% de EAR. As aplicações de SFT+Itafós e SFT+Gafsa podem ser uma alternativa para os sistemas agrícolas, visando a menor utilização de fosfatos acidulados. O desempenho produtivo do milho não foi alterado pelas fontes de P e níveis de inoculação com P. fluorescens

Fontes de P associadas à inoculação de rizobactérias do gênero Pseudomonas no desenvolvimento de plantas de milho.

O estudo teve como objetivo avaliar o efeito de fosfatos solúveis e naturais associados à inoculação de rizobactérias do gênero Pseudomonas via sementes, no desenvolvimento de plantas de milho. O experimento foi conduzido em casa de vegetação, em esquema fatorial 6x3 em blocos casualizados, com quatro repetições. Foram aplicados 50 mg kg-1 de P via solo por meio de cinco fontes: Superfosfato Triplo (SFT), Fosfato Natural Gafsa, Fosfato Natural Itafós, SFT+Gafsa e SFT+Itafós (ambas as misturas na proporção 1:1), além do controle (sem P), associadas a três níveis de inoculação: sem inoculação, estirpe A (Burkholderia pickettii GN 2214) e a estirpe B (Pseudomonas sp. do grupo Fluorescente P21). Por ocasião do florescimento masculino (60 DAE) foram analisadas as seguintes características: massa seca de parte aérea (MSPA), massa seca de raiz (MSR), massa seca total (MST) e a relação raiz/parte aérea (MSR/MSPA). As plantas obtiveram os maiores crescimentos e desenvolvimentos com a aplicação de SFT. A combinação de SFT+Gafsa e SFT+Itafós proporcionaram maior desenvolvimento para MSPA, MSR, e MST em relação aos fosfatos naturais aplicados isoladamente. O controle apresentou a maior relação MSR/MSPA. As estirpes P21 e GN 2214 promovem a biomassa das plantas de milho. As combinações de fosfatos solúveis com naturais constituem uma nova opção para a correção fosfatada para os sistemas de produção agrícolas

Temporal Network Analysis of Literary Texts

We study temporal networks of characters in literature focusing on "Alice's Adventures in Wonderland" (1865) by Lewis Carroll and the anonymous "La Chanson de Roland" (around 1100). The former, one of the most influential pieces of nonsense literature ever written, describes the adventures of Alice in a fantasy world with logic plays interspersed along the narrative. The latter, a song of heroic deeds, depicts the Battle of Roncevaux in 778 A.D. during Charlemagne's campaign on the Iberian Peninsula. We apply methods recently developed by Taylor and coworkers \cite{Taylor+2015} to find time-averaged eigenvector centralities, Freeman indices and vitalities of characters. We show that temporal networks are more appropriate than static ones for studying stories, as they capture features that the time-independent approaches fail to yield.Comment: 17 pages, 11 figure

Data informed learning: A next phase data literacy framework for higher education

This poster was presented at the Association for Information Science and Technology’s (ASIS&T) Annual Meeting in St. Louis, MO on November 9, 2015. Accessing, using and managing data is increasingly recognized as an important learning outcome in higher education. Approaches to data literacy have typically been informed by information literacy. New approaches to information literacy have emerged that address how information is used in the different disciplinary contexts in which people learn and work. Successful approaches to data literacy will also need to address contextual concerns. Informed learning is an approach to information literacy that purposefully addresses contextual concerns by suggesting pedagogic strategies for enabling students to use information in ways that support discipline-focused learning outcomes. As part of an ongoing investigation, we advance data informed learning as a framework for data literacy in higher education that emphasizes how data are used to learn and communicate within disciplinary learning contexts. Drawing from informed learning, we outline principles and characteristics of data informed learning, and suggest future directions to investigate ways that data are used in real-world environments

Stochastic stabilization of cosmological photons

The stability of photon trajectories in models of the Universe that have constant spatial curvature is determined by the sign of the curvature: they are exponentially unstable if the curvature is negative and stable if it is positive or zero. We demonstrate that random fluctuations in the curvature provide an additional stabilizing mechanism. This mechanism is analogous to the one responsible for stabilizing the stochastic Kapitsa pendulum. When the mean curvature is negative it is capable of stabilizing the photon trajectories; when the mean curvature is zero or positive it determines the characteristic frequency with which neighbouring trajectories oscillate about each other. In constant negative curvature models of the Universe that have compact topology, exponential instability implies chaos (e.g. mixing) in the photon dynamics. We discuss some consequences of stochastic stabilization in this context.Comment: 4 pages, 3 postscript figures in color which are also appropriate for black and white printers; v2 emphasizes relevance to flat as well as negatively curved cosmologies; to appear in J. Phys.