Strings vs. spins on the null orbifold

We study the null orbifold singularity in 2+1 d flat space higher spin theory as well as string theory. Using the Chern-Simons formulation of 2+1 d Einstein gravity, we first observe that despite the singular nature of this geometry, the eigenvalues of its Chern-Simons holonomy are trivial. Next, we construct a resolution of the singularity in higher spin theory: a Kundt spacetime with vanishing scalar curvature invariants. We also point out that the UV divergences previously observed in the 2-to-2 tachyon tree level string amplitude on the null orbifold do not arise in the at alpha' -> infinity limit. We find all the divergences of the amplitude and demonstrate that the ones remaining in the tensionless limit are physical IR-type divergences. We conclude with a discussion on the meaning and limitations of higher spin (cosmological) singularity resolution and its potential connection to string theory.

Optimization Of Off-Null Ellipsometry For Air/Solid Interfaces

The optimization of off-null ellipsometry is described with emphasis on the improvement of sample thickness sensitivity. Optimal conditions are dependent on azimuth angle settings of the polarizer, compensator, and analyzer in a polarizer-compensator-sample-analyzer ellipsometer arrangement. Numerical simulation utilized offers an approach to present the dependence of the sensitivity on the azimuth angle settings, from which optimal settings corresponding to the best sensitivity are derived. For a series of samples of SiO2 layer (thickness in the range of 1.8-6.5 nm) on silicon substrate, the theory analysis proves that sensitivity at the optimal settings is increased 20 times compared to that at null settings used in most works, and the relationship between intensity and thickness is simplified as a linear type instead of the original nonlinear type, with the relative error reduced to similar to 1/100 at the optimal settings. Furthermore the discussion has been extended toward other factors affecting the sensitivity of the practical system, such as the linear dynamic range of the detector, the signal-to-noise ratio and the intensity from the light source, etc. Experimental results from the investigation Of SiO2 layer on silicon substrate are chosen to verify the optimization. (c) 2007 Optical Society of America.

Auxiliary particle implementation of the probability hypothesis density filter

Optimal Bayesian multi-target filtering is, in general, computationally impractical owing to the high dimensionality of the multi-target state. The Probability Hypothesis Density (PHD) filter propagates the first moment of the multi-target posterior distribution. While this reduces the dimensionality of the problem, the PHD filter still involves intractable integrals in many cases of interest. Several authors have proposed Sequential Monte Carlo (SMC) implementations of the PHD filter. However, these implementations are the equivalent of the Bootstrap Particle Filter, and the latter is well known to be inefficient. Drawing on ideas from the Auxiliary Particle Filter (APF), we present a SMC implementation of the PHD filter which employs auxiliary variables to enhance its efficiency. Numerical examples are presented for two scenarios, including a challenging nonlinear observation model.

Optimization of Off-Null Ellipsometry for Optical Biosensor Applications

The optimization of off-null ellipsometry is described with emphasis on the improvement of resolution for visualizing biomolecule layers. For optical biosensor with layer thickness below 6.5 nm, a numerical simulation for the dependence of resolution on the azimuth settings of polarizer and analyzer is presented first. For comparison, three different resolutions are given at three azimuth settings which are near null and far away from null condition, respectively. Furthermore, the square or linear approximation relationship between the intensity and the layer thickness are also given at these settings. The difference among their accuracy is up to 100 times or so. Experimental results of the biosensor sample verify the optimization.

Basque nominalizations and the role of structural Case in the licensing of null arguments

[EN] This article investigates the question of the licensing of null arguments in the so-called pro-drop languages. By focusing on the licensing of null subjects in the different types of -T(Z)E nominalizations in Basque, it aims at defining in a precise way the crucial feature that makes pro-drop possible in a clause. The central claim is that what licenses subject-drop is the assignment of structural Case. That is, it is argued that a subject can be null if and only if it is assigned structural Case. Different aspects of T(Z)E nominalizations are also explored, which show that even if these clauses are similar in the surface, they can be syntactically very different and furthermore, that infinitive clauses marked with the same nominalizing morpheme can also have diverging structures.

The interactive brain hypothesis

Enactive approaches foreground the role of interpersonal interaction in explanations of social understanding. This motivates, in combination with a recent interest in neuroscientific studies involving actual interactions, the question of how interactive processes relate to neural mechanisms involved in social understanding. We introduce the Interactive Brain Hypothesis (IBH) in order to help map the spectrum of possible relations between social interaction and neural processes. The hypothesis states that interactive experience and skills play enabling roles in both the development and current function of social brain mechanisms, even in cases where social understanding happens in the absence of immediate interaction. We examine the plausibility of this hypothesis against developmental and neurobiological evidence and contrast it with the widespread assumption that mindreading is crucial to all social cognition. We describe the elements of social interaction that bear most directly on this hypothesis and discuss the empirical possibilities open to social neuroscience. We propose that the link between coordination dynamics and social understanding can be best grasped by studying transitions between states of coordination. These transitions form part of the self-organization of interaction processes that characterize the dynamics of social engagement. The patterns and synergies of this self-organization help explain how individuals understand each other. Various possibilities for role-taking emerge during interaction, determining a spectrum of participation. This view contrasts sharply with the observational stance that has guided research in social neuroscience until recently. We also introduce the concept of readiness to interact to describe the practices and dispositions that are summoned in situations of social significance (even if not interactive). This latter idea links interactive factors to more classical observational scenarios.

Abstention, null and blank votes in the Basque Autonomous Community

The objectives of this essay are twofold. First it reviews the reason for abstaining (or casting a null or blank vote) in elections. It also provides the data of abstention in the elections to the European Parliament. Fewer data are available on blank and null votes. These are provided for some countries. The second objective is to analyze the data of the elections in the Basque Autonomous Community since 1977. The evolution through time is commented. The main features are the low participation in the European elections on the one hand and the importance of the null vote in the 2003-2009 period.

Abstention, null and blank votes in the Basque Autonomous Community

The objectives of this essay are twofold. First it reviews the reason for abstaining (or casting a null or blank vote) in elections. It also provides the data of abstention in the elections to the European Parliament. Fewer data are available on blank and null votes. These are provided for some countries. The second objective is to analyze the data of the elections in the Basque Autonomous Community since 1977. The evolution through time is commented. The main features are the low participation in the European elections on the one hand and the importance of the null vote in the 2003-2009 period.