Ensemble tractography

Fiber tractography uses diffusion MRI to estimate the trajectory and cortical projection zones of white matter fascicles in the living human brain. There are many different tractography algorithms and each requires the user to set several parameters, such as curvature threshold. Choosing a single algorithm with a specific parameters sets poses two challenges. First, different algorithms and parameter values produce different results. Second, the optimal choice of algorithm and parameter value may differ between different white matter regions or different fascicles, subjects, and acquisition parameters. We propose using ensemble methods to reduce algorithm and parameter dependencies. To do so we separate the processes of fascicle generation and evaluation. Specifically, we analyze the value of creating optimized connectomes by systematically combining candidate fascicles from an ensemble of algorithms (deterministic and probabilistic) and sweeping through key parameters (curvature and stopping criterion). The ensemble approach leads to optimized connectomes that provide better cross-validatedprediction error of the diffusion MRI data than optimized connectomes generated using the singlealgorithms or parameter set. Furthermore, the ensemble approach produces connectomes that contain both short- and long-range fascicles, whereas single-parameter connectomes are biased towards one or the other. In summary, a systematic ensemble tractography approach can produce connectomes that are superior to standard single parameter estimates both for predicting the diffusion measurements and estimating white matter fascicles.Fil: Takemura, Hiromasa. University of Stanford; Estados Unidos. Osaka University; JapónFil: Caiafa, César Federico. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Wandell, Brian A.. University of Stanford; Estados UnidosFil: Pestilli, Franco. Indiana University; Estados Unido

Maximum Search Using P Systems

Several algorithms of maximum search are investigated and eval- uated in different types of P systems, namely using priorities, multiple nested membranes and linked transport. The proposed solutions are expected to find application in a wide range of problems. In particular, the authors are currently working on modeling an algorithm for DNA sequence alignment using P systems

Emerging Vectors of Narratology: Toward Consolidation or Diversification?

This is an introduction to the interviews redacted as a follow-up of the 2013 ENN conference. The discussions that originated at the conference were rich and thought-provoking and so the editors of this special section of «Enthymema» decided to continue the dialogue about the state of the art and the future of narratology

Photoinduced inverse spin Hall effect in Pt/Ge(001) at room temperature

We performed photoinduced inverse spin Hall effect (ISHE) measurements on a Pt/Ge(001) junction at room temperature. The spin-oriented electrons, photogenerated at the direct gap of Ge using circularly polarized light, provide a net spin current which yields an electromotive field E_ISHE in the Pt layer. Such a signal is clearly detected at room temperature despite the strong {\Gamma} to L scattering which electrons undergo in the Ge conduction band. The ISHE signal dependence on the exciting photon energy is in good agreement with the electron spin polarization expected for optical orientation at the direct gap of Ge

SIMNET: simulation-based exercises for computer net-work curriculum through gamification and augmented reality

Gamification and Augmented Reality techniques, in recent years, have tackled many subjects and environments. Its implementation can, in particular, strengthen teaching and learning processes in schools and universities. Therefore, new forms of knowledge, based on interactions with objects, contributing game, experimentation and collaborative work. Through the technologies mentioned above, we intend to develop an application that serves as a didactic tool, giving support in the area of Computer Networks. This application aims to stand out in simulated controlled environments to create computer networks, taking into ac-count the necessary physical devices and the different physical and logical topologies. The main goal is to enrich the students’ learning experiences and contrib-ute to teacher-student interaction, through collaborative learning provided by the tool, minimizing the need for expensive equipment in learning environments.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

MCDM approach for planning a sustainable livestock enterprise

Beside the livestock activity provides excellent nutritional ingredients for the human diet, growing conflict among stakeholders are caused by the sharing of the property rights about the environment. Traditionally livestock management was focused on profit maximization related to scale economies, however an increasing number of stakeholders are concerned about the negative side effect of environmental externalities and solicit to adopt sustainable technologies to curb the natural resource depletion, soil and water pollution, gaseous emissions and others. Purpose of this paper is to introduce a revisited multi-criteria decision making approach based on solid theoretical fundaments to produce sustainable solutions to achieve economic, social and environmental objectives

Rainfall estimation by combining radar and infrared satellite data for nowcasting purposes

The aim is to evaluate the use of infrared satellite precipitation estimates for nowcasting purposes in the context of a real-time flood-warning scheme. A radar-based calibration technique is described which is applied to the Negri–Adler–Wetzel scheme. This procedure employs radar data over a defined calibration area to estimate, for each satellite image, actual rain-rates to be used in the Negri–Adler–Wetzel scheme. Calibrated satellite estimates obtained from this procedure can be used to diagnose areas of precipitation beyond radar range, thus allowing an extension of precipitation nowcasting lead time. Calibrated estimates are compared with radar rainfall measurements and results are discussed for various sizes of integration area. Calibration reduces consistently both bias and variance of the error of the original Negri–Adler–Wetzel estimates, even for integration areas as small as 2000 km2. This indicates the capabilities of the new technique for nowcasting purposes over mediumsized river basins. Copyright © 1999 Royal Meteorological Societ