Paraxial speckle-based metrology systems with an aperture

Digital speckle photography can be used in the analysis of surface motion in combination with an optical linear canonical transform (LCT). Previously [D. P. Kelly et al. Appl. Opt.44, 2720 (2005)] it has been shown that optical fractional Fourier transforms (OFRTs) can be used to vary the range and sensitivity of speckle-based metrology systems, allowing the measurement of both the magnitude and direction of tilting (rotation) and translation motion simultaneously, provided that the motion is captured in two separate OFRT domains. This requires two bulk optical systems. We extend the OFRT analysis to more general LCT systems with a single limiting aperture. The effect of a limiting aperture in LCT systems is examined in more detail by deriving a generalized Yamaguchi correlation factor. We demonstrate the benefits of using an LCT approach to metrology design. Using this technique, we show that by varying the curvature of the illuminating field, we can effectively change the output domain. From a practical perspective this means that estimation of the motion of a target can be achieved by using one bulk optical system and different illuminating conditions. Experimental results are provided to support our theoretical analysis.     

Differentiation of sCJD and vCJD forms by automated analysis of basal ganglia intensity distribution in multisequence MRI of the brain--definition and evaluation of new MRI-based ratios

We present a method for the analysis of basal ganglia (including the thalamus) for accurate detection of human spongiform encephalopathy in multisequence magnetic resonance imaging (MRI) of the brain. One common feature of most forms of prion protein diseases is the appearance of hyperintensities in the deep grey matter area of the brain in T2-weighted magnetic resonance (MR) images. We employ T1, T2, and Flair-T2 MR sequences for the detection of intensity deviations in the internal nuclei. First, the MR data are registered to a probabilistic atlas and normalized in intensity. Then smoothing is applied with edge enhancement. The segmentation of hyperintensities is performed using a model of the human visual system. For more accurate results, a priori anatomical data from a segmented atlas are employed to refine the registration and remove false positives. The results are robust over the patient data and in accordance with the clinical ground truth. Our method further allows the quantification of intensity distributions in basal ganglia. The caudate nuclei are highlighted as main areas of diagnosis of sporadic Creutzfeldt-Jakob Disease (sCJD), in agreement with the histological data. The algorithm permitted the classification of the intensities of abnormal signals in sCJD patient FLAIR images with a higher hypersignal in caudate nuclei (10/10) and putamen (6/10) than in thalami. Defining normalized MRI measures of the intensity relations between the internal grey nuclei of patients, we robustly differentiate sCJD and variant CJD (vCJD) patients, in an attempt to create an automatic classification tool of human spongiform encephalopathies.     

Actin Stress Fibers Response and Adaptation under Stretch

One of the many effects of soft tissues under mechanical solicitation in the cellular damage produced by highly localized strain. Here, we study the response of peripheral stress fibers (SFs) to external stretch in mammalian cells, plated onto deformable micropatterned substrates. A local fluorescence analysis reveals that an adaptation response is observed at the vicinity of the focal adhesion sites (FAs) due to its mechanosensor function. The response depends on the type of mechanical stress, from a Maxwell-type material in compression to a complex scenario in extension, where a mechanotransduction and a self-healing process takes place in order to prevent the induced severing of the SF. A model is proposed to take into account the effect of the applied stretch on the mechanics of the SF, from which relevant parameters of the healing process are obtained. In contrast, the repair of the actin bundle occurs at the weak point of the SF and depends on the amount of applied strain. As a result, the SFs display strain-softening features due to the incorporation of new actin material into the bundle. In contrast, the response under compression shows a reorganization with a constant actin material suggesting a gliding process of the SFs by the myosin II motors.     

Sediment bed destabilization by an isolated vortex:an experimental approach

The destabilization of an erodible sediment bed by a reproducible impulsive phenomenon is studied experimentally.For this,a specific setup is designed to produc...     

Adding Federated Identity Management to OpenStack

OpenStack is an open source cloud computing project that is enjoying wide. While many cloud deployments may be stand-alone, it is clear that secure federated community clouds, i.e., inter-clouds, are needed. Hence, there must be methods for federated identity management (FIM) that enable authentication and authorisation to be flexibly enforced across federated environments. Since there are many different FIM protocols either in use or in development today, this paper addresses the goal of adding protocol independent federated identity management to the OpenStack services. After giving a motivating example for secure cloud federation, and describing the conceptual design for protocol independent federated access, a detailed federated identity protocol sequence is presented. The paper then describes the implementation of the protocol independent system components, along with the incorporation of two different FIM protocols, namely SAML and Keystone proprietary. Finally performance measurements of the protocol independent components, and the two different protocols dependent components are presented, before the paper concludes with the current limitations.     

A time-series prediction approach for feature extraction in a brain-computer interface.

This paper presents a feature extraction procedure (FEP) for a brain-computer interface (BCI) application where features are extracted from the electroencephalogram (EEG) recorded from subjects performing right and left motor imagery. Two neural networks (NNs) are trained to perform one-step-ahead predictions for the EEG time-series data, where one NN is trained on right motor imagery and the other on left motor imagery. Features are derived from the power (mean squared) of the prediction error or the power of the predicted signals. All features are calculated from a window through which all predicted signals pass. Separability of features is achieved due to the morphological differences of the EEG signals and each NNs specialization to the type of data on which it is trained. Linear discriminant analysis (LDA) is used for classification. This FEP is tested on three subjects off-line and classification accuracy (CA) rates range between 88% and 98%. The approach compares favorably to a well-known adaptive autoregressive (AAR) FEP and also a linear AAR model based prediction approach.     

解决推出大规模物联网方案的挑战

物联网(IoT)为用户和企业带来了许多机会,为我们日常生活的许多方面增添了自动化和更强大的功能,包括商业环境和个人生活.许多新公司正带着创新的想法和解决方案进入IoT市场,这将在不久的将来提供更多增强的功能. IoT领域大量初创企业的出现主要是由于元器件和子系统供应商以评估板、参考设计和详细文档的形式提供广泛的设计支持...     

Confinement Effects on the Structure of Entropy-Induced Supercrystals

Depletion-induced self-assembly is routinely used to separate plasmonic nanoparticles (NPs) of different shapes, but less often for its ability to create supercrystals (SCs) in suspension. Therefore, these plasmonic assemblies have not yet reached a high level of maturity and their in-depth characterization by a combination of in situ techniques is still very much needed. In this work, gold triangles (AuNTs) and silver nanorods (AgNRs) are assembled by depletion-induced self-assembly. Small Angle X-ray Scattering (SAXS) and scanning electron microscopy (SEM) analysis shows that the AuNTs and AgNRs form 3D and 2D hexagonal lattices in bulk, respectively. The colloidal crystals are also imaged by in situ Liquid-Cell Transmission Electron Microscopy. Under confinement, the affinity of the NPs for the liquid cell windows reduces their ability to stack perpendicularly to the membrane and lead to SCs with a lower dimensionality than their bulk counterparts. Moreover, extended beam irradiation leads to disassembly of the lattices, which is well described by a model accounting for the desorption kinetics highlighting the key role of the NP-membrane interaction in the structural properties of SCs in the liquid-cell. The results shed light on the reconfigurability of NP superlattices obtained by depletion-induced self-assembly, which can rearrange under confinement.     

Robust Pointset Denoising of Piecewise-Smooth Surfaces through Line Processes

Denoising is a common, yet critical operation in geometry processing aiming at recovering high-fidelity models of piecewise-smooth objects from noise-corrupted pointsets. Despite a sizable literature on the topic, there is a dearth of approaches capable of processing very noisy and outlier-ridden input pointsets for which no normal estimates and no assumptions on the underlying geometric features or noise type are provided. In this paper, we propose a new robust-statistics approach to denoising pointsets based on line processes to offer robustness to noise and outliers while preserving sharp features possibly present in the data. While the use of robust statistics in denoising is hardly new, most approaches rely on prescribed filtering using data-independent blending expressions based on the spatial and normal closeness of samples. Instead, our approach deduces a geometric denoising strategy through robust and regularized tangent plane fitting of the initial pointset, obtained numerically via alternating minimizations for efficiency and reliability. Key to our variational approach is the use of line processes to identify inliers vs. outliers, as well as the presence of sharp features. We demonstrate that our method can denoise sampled piecewise-smooth surfaces for levels of noise and outliers at which previous works fall short.