Mixture of Species Sampling Models

We introduce mixtures of species sampling sequences (mSSS) and discuss how these sequences are related to various types of Bayesian models. As a particular case, we recover species sampling sequences with general (not necessarily diffuse) base measures. These models include some “spike-and-slab” non-parametric priors recently introduced to provide sparsity. Furthermore, we show how mSSS arise while considering hierarchical species sampling random probabilities (e.g., the hierarchical Dirichlet process). Extending previous results, we prove that mSSS are obtained by assigning the values of an exchangeable sequence to the classes of a latent exchangeable random partition. Using this representation, we give an explicit expression of the Exchangeable Partition Probability Function of the partition generated by an mSSS. Some special cases are discussed in detail—in particular, species sampling sequences with general base measures and a mixture of species sampling sequences with Gibbs-type latent partition. Finally, we give explicit expressions of the predictive distributions of an mSSS.

Marcinkiewicz–Zygmund Inequalities for Polynomials in Bergman and Hardy Spaces

We study the relationship between sampling sequences in infinite dimensional Hilbert spaces of analytic functions and Marcinkiewicz–Zygmund inequalities in subspaces of polynomials. We focus on the study of the Hardy space and the Bergman space in one variable because they provide two settings with a strikingly different behavior.

4D deep learning for real-time volumetric optical coherence elastography

Purpose Elasticity of soft tissue provides valuable information to physicians during treatment and diagnosis of diseases. A number of approaches have been proposed to estimate tissue stiffness from the shear wave velocity. Optical coherence elastography offers a particularly high spatial and temporal resolution. However, current approaches typically acquire data at different positions sequentially, making it slow and less practical for clinical application. Methods We propose a new approach for elastography estimations using a fast imaging device to acquire small image volumes at rates of 831 Hz. The resulting sequence of phase image volumes is fed into a 4D convolutional neural network which handles both spatial and temporal data processing. We evaluate the approach on a set of image data acquired for gelatin phantoms of known elasticity. Results Using the neural network, the gelatin concentration of unseen samples was predicted with a mean error of 0.65 ± 0.81 percentage points from 90 subsequent volumes of phase data only. We achieve a data acquisition and data processing time of under 12 ms and 22 ms, respectively. Conclusions We demonstrate direct volumetric optical coherence elastography from phase image data. The approach does not rely on particular stimulation or sampling sequences and allows the estimation of elastic tissue properties of up to 40 Hz.

Fast Localization of Impact Damage on Woven CFRP Based on Sparse Microwave Imaging

Microwave open-ended waveguide scanning has been proved to be a promising NDT technique for imaging of woven carbon fiber reinforced plastic (CFRP) with impact damages. However, it uses a conventional C-scan technique, which is excessively time-consuming and therefore it is not practical for defect detection in a large area. Moreover, without proper feature extraction, the appearance of woven texture within the impact damage area opposes to the localization of the impact. This work proposes a novel framework for fast impact damage localization by means of discrete sparse measurement. Also, the localization accuracy of sparse measurement is improved by mitigating effect of woven texture using principal component analysis (PCA) for feature extraction. The performance of the proposed methods is evaluated by sets of incremental measurements. The performance of the proposed system is and evaluated by localizing the impact damage of 100 non-uniform sparse sampling sequences. Results show that our proposed technique can accurately localize the impact damage with number of samples less than 10% of full measurements, giving approximately 10 times faster than that of the conventional C-scan.

A Bandwidth Mismatch Optimization Technique in Time-Interleaved Analog-to-Digital Converters

In time-interleaved (TI) analog-to-digital converters (ADCs), bandwidth mismatches, caused by the limited bandwidth of input signal traces and sample circuits, seriously deteriorate the spurious-free dynamic range (SFDR) of the system. This paper analyzes the influence of bandwidth mismatch errors under different sampling sequences. Eventually, based on a randomization technique and the simulated annealing algorithm (SAA), a bandwidth mismatch optimization technique is presented that can work well with other bandwidth mismatch calibration methods. The behavior simulation results indicate that an improvement of 7[Formula: see text]dB in the SFDR can be achieved with this technique in a 16-channel TI-ADC after timing and gain calibration.

An expanded molecular phylogeny of metaine spiders (Araneae, Tetragnathidae) with description of new taxa from Taiwan and the Philippines

Despite numerous phylogenetic analyses of the orb-weaving spider family Tetragnathidae, several relationships from the subfamily to species level are tenuous or unclear. One such example regards the validity and composition of the tetragnathid subfamily Metainae, which historically has mixed support and limited taxon sampling. Sequences for six genetic markers – 12S, 16S, 18S, 28S, cytochrome c oxidase I and histone H3 – were analysed for 78 taxa, including 10 that were completely new or with increased markers. Analysed in both maximum likelihood and Bayesian frameworks, we find good support for Metainae for the first time. The subfamily includes three previously described genera – Meta, Metellina and Dolichognatha – in addition to one described herein, Zhinu Kallal & Hormiga, gen. nov., from Taiwan. Also within Metainae, we synonymise Metellina with the monotypic Menosira and reaffirm the synonymy of Dolichognatha with Prolochus. Finally, we describe a new species of leucaugine tetragnathid from the Philippines, Orsinome megaloverpa, sp. nov., the second member of Orsinome to be placed in a phylogenetic context.