A Search for Gravitational Milli–Lenses

We have searched for gravitational milli–lens systems by examining VLBI maps of ~ 300 flat–spectrum radio sources. So far we have followed up 7 candidates, with separations in the range 2–20 mas. None have been confirmed as lenses but several of them can not yet be definitively ruled out. If there are no milli-lenses in this sample then uniformly–distributed black holes of 10^6 to 10^8 M_⊙ cannot contribute more than ~ 1% of the closure density

NDE of Thick Composites in the Aerospace Industry — An Overview

Designers are turning to thick fiber reinforced composites, with increasing success, in order to meet the unique structural requirements which arise within the aerospace industry. These composites offer many superior properties, especially in the design of solid rocket motor cases, where there is a tremendous potential for advantage in strength-to-weight and stiffness-to-weight ratios over conventional materials [1,2]. The increased use of thick fiber reinforced composites presents quite a challenge to the NonDestructive Evaluation (NDE) community. To inspect these materials, conventional NDE techniques must be modified and/or new techniques must be developed to permit interrogation of the full material thickness and adjacent bondlines. Thick fiber reinforced composites exhibit a degree of anisotropy that is orders of magnitude above that of previously employed structural materials (i.e., metals). This anisotropy stems not only from the basic construction of the composite (oriented fibers imbedded within a matrix), but also from what are currently considered “acceptable flaws” within the material (varying degrees of delamination, matrix cracking, porosity, etc.). Successful NDE requires that one be able to distinguish the signals from these “acceptable flaws” from those deemed unacceptable. For the detection of some types of flaws, conventional techniques can be applied to composites with only slight modification, whereas for others, new techniques must be developed. For instance, recently, a large (expensive) solid rocket motor segment sustained an accidental impact. Standard ultrasonic inspection techniques successfully revealed delaminations between a number of layers in the composite case beneath the point of contact. Structural analysis, however, indicated that additional information regarding the degree of fiber breakage was needed. Unfortunately, since no NDE technique was available to assess the degree of fiber breakage, the contractor had to assume the worst and, consequently, scrap the motor

The Milliarcsecond Structure of Radio Galaxies and Quasars

Hybrid maps of the nuclei of radio galaxies and quasars show a variety of morphologies. Among compact sources, two structures are common: an asymmetric, “core-jet” morphology (eg, 3C 273), and an “equal double” morphology with two separated, similar components (eg, CTD 93). The nuclei of extended, double radio galaxies generally have a core-jet morphology with the jet directed toward one of the outer components

A unified wavelet-based modelling framework for non-linear system identification: the WANARX model structure

A new unified modelling framework based on the superposition of additive submodels, functional components, and wavelet decompositions is proposed for non-linear system identification. A non-linear model, which is often represented using a multivariate non-linear function, is initially decomposed into a number of functional components via the wellknown analysis of variance (ANOVA) expression, which can be viewed as a special form of the NARX (non-linear autoregressive with exogenous inputs) model for representing dynamic input–output systems. By expanding each functional component using wavelet decompositions including the regular lattice frame decomposition, wavelet series and multiresolution wavelet decompositions, the multivariate non-linear model can then be converted into a linear-in-theparameters problem, which can be solved using least-squares type methods. An efficient model structure determination approach based upon a forward orthogonal least squares (OLS) algorithm, which involves a stepwise orthogonalization of the regressors and a forward selection of the relevant model terms based on the error reduction ratio (ERR), is employed to solve the linear-in-the-parameters problem in the present study. The new modelling structure is referred to as a wavelet-based ANOVA decomposition of the NARX model or simply WANARX model, and can be applied to represent high-order and high dimensional non-linear systems

The mapping class group and the Meyer function for plane curves

For each d>=2, the mapping class group for plane curves of degree d will be defined and it is proved that there exists uniquely the Meyer function on this group. In the case of d=4, using our Meyer function, we can define the local signature for 4-dimensional fiber spaces whose general fibers are non-hyperelliptic compact Riemann surfaces of genus 3. Some computations of our local signature will be given.Comment: 24 pages, typo adde

MIRO: A robot “Mammal” with a biomimetic brain-based control system

We describe the design of a novel commercial biomimetic brain-based robot, MIRO, developed as a prototype robot companion. The MIRO robot is animal-like in several aspects of its appearance, however, it is also biomimetic in a more significant way, in that its control architecture mimics some of the key principles underlying the design of the mammalian brain as revealed by neuroscience. Specifically, MIRO builds on decades of previous work in developing robots with brain-based control systems using a layered control architecture alongside centralized mechanisms for integration and action selection. MIRO’s control system operates across three core processors, P1-P3, that mimic aspects of spinal cord, brainstem, and forebrain functionality respectively. Whilst designed as a versatile prototype for next generation companion robots, MIRO also provides developers and researchers with a new platform for investigating the potential advantages of brain-based control

Olive shrub buried on Therasia supports a mid-16th century BCE date for the Thera eruption

The precise date of the 2nd millennium BCE (“Minoan”) eruption of Thera (Santorini) has long been a focus of controversy due to a discrepancy between archaeological and radiocarbon-based dating of materials from stratigraphic layers above and below tsunami, ash and pumice deposits resulting from the eruption. A critical, though controversial, piece of evidence has been four segments of a radiocarbon-dated olive tree branch, buried on Thera during the eruption. Here we report new radiocarbon evidence from an olive shrub found carbonized by the same eruption deposits on neighboring Therasia (Santorini). The Therasia olive shrub dates slightly younger than the previous olive branch. Calibrated results and growth increment counts indicate increased probabilities for a mid-16th century BCE date for the eruption, overlapping with multiple volcanic sulfate markers from ice core records

Observational Properties of Jets in Active Galactic Nuclei

Parsec scale jet properties are shortly presented and discussed. Observational data are used to derive constraints on the jet velocity and orientation, the presence of velocity structures, and the connection between the pc and kpc scale. Two peculiar sources with limb-brightened jets: 1144+35 and Mkn 501 are discussed in detail.Comment: 13 pages with 7 figures. To appear in "Virtual Astrophysical Jets" APSS, Kluwer Academic Publisher - Massaglia, Bodo, Rossi eds - in pres

Interview on Kinship and Household

Peer reviewe

Neurophysiological evidence of motor preparation in inner speech and the effect of content predictability

Self-generated overt actions are preceded by a slow negativity as measured by electroencephalogram, which has been associated with motor preparation. Recent studies have shown that this neural activity is modulated by the predictability of action outcomes. It is unclear whether inner speech is also preceded by a motor-related negativity and inf luenced by the same factor. In three experiments, we compared the contingent negative variation elicited in a cue paradigm in an active vs. passive condition. In Experiment 1, participants produced an inner phoneme, at which an audible phoneme whose identity was unpredictable was concurrently presented. We found that while passive listening elicited a late contingent negative variation, inner speech production generated a more negative late contingent negative variation. In Experiment 2, the same pattern of results was found when participants were instead asked to overtly vocalize the phoneme. In Experiment 3, the identity of the audible phoneme was made predictable by establishing probabilistic expectations. We observed a smaller late contingent negative variation in the inner speech condition when the identity of the audible phoneme was predictable, but not in the passive condition. These findings suggest that inner speech is associated with motor preparatory activity that may also represent the predicted action-effects of covert actions