Temporal kernel CCA and its application in multimodal neuronal data analysis

Data recorded from multiple sources sometimes exhibit non-instantaneous couplings. For simple data sets, cross-correlograms may reveal the coupling dynamics. But when dealing with high-dimensional multivariate data there is no such measure as the cross-correlogram. We propose a simple algorithm based on Kernel Canonical Correlation Analysis (kCCA) that computes a multivariate temporal filter which links one data modality to another one. The filters can be used to compute a multivariate extension of the cross-correlogram, the canonical correlogram, between data sources that have different dimensionalities and temporal resolutions. The canonical correlogram reflects the coupling dynamics between the two sources. The temporal filter reveals which features in the data give rise to these couplings and when they do so. We present results from simulations and neuroscientific experiments showing that tkCCA yields easily interpretable temporal filters and correlograms. In the experiments, we simultaneously performed electrode recordings and functional magnetic resonance imaging (fMRI) in primary visual cortex of the non-human primate. While electrode recordings reflect brain activity directly, fMRI provides only an indirect view of neural activity via the Blood Oxygen Level Dependent (BOLD) response. Thus it is crucial for our understanding and the interpretation of fMRI signals in general to relate them to direct measures of neural activity acquired with electrodes. The results computed by tkCCA confirm recent models of the hemodynamic response to neural activity and allow for a more detailed analysis of neurovascular coupling dynamics.     

Evaluating the relationship between chemical exposure and cryptorchidism

One method for the evaluation of complex environmental and health datasets is the discrete mathematical method Hasse diagram technique based on partial orders. The introduced software program package is named PyHasse. In this paper we evaluate a possible human association between maternal exposure to organochlorine compounds used as pesticides and cryptorchidism among male children in Finland and Denmark. We identified differences in comparable and incomparable objects and quantified these differences by the software tool Similarity Analysis in the program PyHasse. Furthermore we interpreted the corresponding Hasse diagrams concerning chosen “striking objects”. We found the position of the chemicals AHCH (alpha-Hexachlorohexane), CHCE (cis-Heptachloroepoxide), DIEL (Dieldrin), and MIRE (Mirex) has some influence on the differentiation of the Hasse diagrams and hence of each two datasets analyzed. The largest disparities can be observed when we compare the Finnish and Danish datasets concerning cryptorchidism. The disparities are demonstrated in the corresponding Hasse diagrams.     

Facets of the Fully Mixed Nash Equilibrium Conjecture

In this work, we continue the study of the many facets of the Fully Mixed Nash Equilibrium Conjecture, henceforth abbreviated as the FMNE\mathsf{FMNE} Conjecture, in selfish routing for the special case of n identical users over two (identical) parallel links. We introduce a new measure of Social Cost, defined as the expectation of the square of the maximum congestion on a link; we call it Quadratic Maximum Social Cost. A Nash equilibrium is a stable state where no user can improve her (expected) latency by switching her mixed strategy; a worst-case Nash equilibrium is one that maximizes Quadratic Maximum Social Cost. In the fully mixed Nash equilibrium, all mixed strategies achieve full support.     

ITEA—interactive trajectories and events analysis: exploring sequences of spatio-temporal events in movement data

Widespread use of GPS and similar technologies makes it possible to collect extensive amounts of trajectory data. These data sets are essential for reasonable decision making in various application domains. Additional information, such as events taking place along a trajectory, makes data analysis challenging, due to data size and complexity. We present an integrated solution for interactive visual analysis and exploration of events along trajectories data. Our approach supports analysis of event sequences at three different levels of abstraction, namely spatial, temporal, and events themselves. Customized views as well as standard views are combined to form a coordinated multiple views system. In addition to trajectories and events, we include on-the-fly derived data in the analysis. We evaluate our integrated solution using the IEEE VAST 2015 Challenge data set. A successful detection and characterization of malicious activity indicate the usefulness and efficiency of the presented approach.     

Relations between specific heat discontinuities and Ginzburg-Landau parameters for superfluid 3He

We show that the value of the ratio ₅/₂₄ deduced from specific heat experiments is extremely sensitive to the coefficient of the quadratic term in the Ginzburg-Landau functional. A strong coupling calculation of this coefficient implies that the experimental value of ₅/₂₄ is more than three times larger than previously believed.This work was supported in part by the National Science Foundation through Grant DMR7826530.     

Electrical properties of the grain boundaries of oxygen ion conductors: Acceptor-doped zirconia and ceria

This article reviews the current understanding of the electrical properties of the grain boundaries of acceptor-doped zirconia and ceria, however, with an emphasis on the grain-boundary defect structure. From an electrical point of view, a grain boundary consists of a grain-boundary core and two adjacent space-charge layers. The grain-boundary cores of acceptor-doped zirconia and ceria are positively charged, probably owing to the oxygen vacancy enrichment there. Oxygen vacancies are therefore depleted in the space-charge layer. The grain-boundary conductivities of acceptor-doped zirconia and ceria are at least two orders of magnitude lower than the corresponding bulk values, depending on temperature and dopant level. Such a phenomenon is due to the facts: (1) that oxygen vacancies are severely depleted in the space-charge layer, and (2) that the grain-boundary impurity phase blocks the ionic transport across the grain boundaries by decreasing the conduction path width and constricting current lines. In materials of high purity, the effect of the space-charge depletion layer is dominant; however, in materials of normal purity, the effect of the grain-boundary impurity phase is dominant. A Schottky barrier model satisfactorily explains all the phenomenological observations of the grain-boundary electrical properties of materials of high purity, and experimental evidence soundly supports the model. Various factors (alumina addition and grain size) influencing the grain-boundary electrical properties are discussed, and some special aspects of nanocrystalline materials are highlighted.     

打破固定／移动电信网络界限 WiMax 802．16e行动自如

WiMax最大的胜利是吸引了一群无线宽带厂商，同时通过最佳技术、标准平台和开放协议让业界对下一代宽带无线基础设施达成广泛共识。本文将从市场应用和上市时间的角度探讨WiMax带给无线宽带产业的商机，以及对于生产制造和服务业的正面影响，并剖析固网业者如何透过它进入移动服务市场以扩大营收来源。