Generative Learning of Heterogeneous Tail Dependence

We propose a multivariate generative model to capture the complex dependence structure often encountered in business and financial data. Our model features heterogeneous and asymmetric tail dependence between all pairs of individual dimensions while also allowing heterogeneity and asymmetry in the tails of the marginals. A significant merit of our model structure is that it is not prone to error propagation in the parameter estimation process, hence very scalable, as the dimensions of datasets grow large. However, the likelihood methods are infeasible for parameter estimation in our case due to the lack of a closed-form density function. Instead, we devise a novel moment learning algorithm to learn the parameters. To demonstrate the effectiveness of the model and its estimator, we test them on simulated as well as real-world datasets. Results show that this framework gives better finite-sample performance compared to the copula-based benchmarks as well as recent similar models

Design and implementation of an integrated surface texture information system for design, manufacture and measurement

The optimised design and reliable measurement of surface texture are essential to guarantee the functional performance of a geometric product. Current support tools are however often limited in functionality, integrity and efficiency. In this paper, an integrated surface texture information system for design, manufacture and measurement, called “CatSurf”, has been designed and developed, which aims to facilitate rapid and flexible manufacturing requirements. A category theory based knowledge acquisition and knowledge representation mechanism has been devised to retrieve and organize knowledge from various Geometrical Product Specifications (GPS) documents in surface texture. Two modules (for profile and areal surface texture) each with five components are developed in the CatSurf. It also focuses on integrating the surface texture information into a Computer-aided Technology (CAx) framework. Two test cases demonstrate design process of specifications for the profile and areal surface texture in AutoCAD and SolidWorks environments respectively

Towards a new definition of areal surface texture parameters on freeform surface

Current definitions and computation of areal surface texture parameters are based on planar, measured or unwrapped, surface which is not applicable for non planar irregular meshes. In this paper an extension of areal surface texture parameters (height and hybrid parameters) for freeform surface is proposed. The proposed method can be used for both general and complex surfaces and it works well on surfaces where there are undercuts and non uniformly spaced points. The proposed method has been tested on six sets of different types of surfaces and the computed parameter results were compared with the values of the parameters defined in ISO 25178-2:2012

Non-overlap subaperture interferometric testing for large optics

It has been shown that the number of subapertures and the amount of overlap has a significant influence on the stitching accuracy. In this paper, a non-overlap subaperture interferometric testing method (NOSAI) is proposed to inspect large optical components. This method would greatly reduce the number of subapertures and the influence of environmental interference while maintaining the accuracy of reconstruction. A general subaperture distribution pattern of NOSAI is also proposed for the large rectangle surface. The square Zernike polynomial is employed to fit such wavefront. The effect of the minimum fitting terms on the accuracy of NOSAI and the sensitivities of NOSAI to subaperture’s alignment error, power systematic error, and random noise are discussed. Experimental results validate the feasibility and accuracy of the proposed NOSAI in comparison with wavefront obtained by a large aperture interferometer and stitching surface by multi-aperture overlap-scanning technique (MAOST)

Curcumin Downregulates Phosphate Carrier and Protects against Doxorubicin Induced Cardiomyocyte Apoptosis

Aim. To explore the effects of curcumin on phosphate carrier (PiC) and its role in protection against doxorubicin induced myocyte toxicity. Methods. Using H9c2 cell line, the cardiotoxic effect of doxorubicin and its mitigation by curcumin were studied. H9c2 cells were cultured with doxorubicin and/or curcumin at various concentrations. Analysis for apoptosis of H9c2 was done using flow cytometry. Confocal laser scanning microscopy was used to record the fluorescence intensity ratios and to determine the mitochondrial permeability transition pore (MPTP) opening state. Oxidative stress was measured using glutathione level, superoxide dismutase activities, and malondialdehyde content. The effect of doxorubicin and curcumin on PiC gene expression was measured by real-time PCR. Results. Curcumin decreased mRNA of PiC and was partly protective against oxidative stress, loss of mitochondrial transmembrane potential, and apoptosis induced by doxorubicin. Interestingly, the effect was not clearly dose dependent and the concentration of 12 mg/L was more efficient than 15 and 10 mg/L. Conclusion. Curcumin downregulates PiC and partly protects against doxorubicin induced oxidative stress and myocyte apoptosis

An unambiguous expression method of the surface texture

The current specification and verification of surface texture in international standards are considered to be too theoretical, complex and over-elaborate for industry. A functional approach that completely expresses the complicated surface texture knowledge for designers and engineers is often nonexistent on the shop floor. Based on Geometrical Product Specification (GPS) philosophy, this paper proposes an unambiguous expression schema of surface texture. The surface texture knowledge in design, manufacture and measurement is based on the general GPS matrix and structured by a categorical object model. Explicit specification and verification processes and the mapping between them are presented. The ultimate goal is to improve the collaboration and bridge the knowledge gap between design, manufacture and measurement of surface texture to reduce product development lead time and improve product quality and performance