Reconstruction of transparent objects using phase shifting profilometry based on diffusion models.

Phase shifting profilometry is an important technique for reconstructing the three-dimensional (3D) geometry of objects with purely diffuse surfaces. However, it is challenging to measure the transparent objects due to the pattern aliasing caused by light refraction and multiple reflections inside the object. In this work, we analyze the aliasing fringe pattern formation for transparent objects and then, propose to learn the front surface light intensity distribution based on the formation principle by using the diffusion models for generating the non-aliased fringe patterns reflected from the front surface only. With the generated fringe patterns, the 3D shape of the transparent objects can be reconstructed via the conventional structured light. We show the feasibility and performance of the proposed method on the data of purely transparent objects that are not seen in the training stage. Moreover, we found it could be generalized to other cases with local-transparent and translucent objects, showing the potential capability of the diffusion based learnable framework in tackling the problems of transparent object reconstruction.

Metformin Inhibits Multiple Myeloma Serum-induced Endothelial Cell Thrombosis by Down-Regulating miR-532.

BACKGROUND: Thrombotic complications in multiple myeloma (MM) impairs the quality of life in patients. Metformin has a certain effect on anti-thrombosis, but its role and mechanism in MM-induced thrombosis are still uncovered. Therefore, this study evaluated the effect of metformin on MM-induced thrombosis. METHODS: Human umbilical vein endothelial cells (HUVECs) were exposed to normal serum (15%), MM serum (15%), metformin (0.01 mmol/L), or MM serum, and metformin simultaneously. The expression of tissue factor (TF) in HUVECs was detected by flow cytometry and quantitative real-time polymerase chain reaction PCR (qRT-PCR). QRT-PCR was also used to determine the expressions of endothelial protein C receptor (EPCR) and miR-532. The generation of thrombin and activated protein C was measured by thrombin generation and protein C activation assays. EPCR, extracellular signal-regulated kinase (ERK) 1/2, p38 mitogen activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathway related protein expressions were detected by western blot. RESULTS: MM serum increased the expressions of TF and miR-532, induced thrombin generation, inhibited EPCR and protein C activation in HUVECs. And metformin could reverse the effects of MM serum on the expressions of TF, EPCR and miR-532, thrombin generation, protein C activation in HUVECs. However, miR-532 mimic reversed the effects of metformin and promoted the levels of thrombosis-related indicators in HUVECs. Moreover, metformin activated the ERK 1/2, p38 MAPK, and NF-κB pathways but miR-532 mimic suppressed the pathway activation. CONCLUSIONS: Metformin played an inhibitory effect on MM serum-induced HUVEC thrombosis, suggesting that metformin could serve as a novel antithrombotic approach for MM patients.

Tri-wavelength simultaneous ESPI for 3D micro-deformation field measurement.

Electronic speckle pattern interferometry (ESPI), a well-established technique for micro-deformation measurement, can be used to determine both in-plane and out-of-plane displacement components. Although many works in ESPI have been reported for three-dimensional (3D) displacement measurement, few works have focused on the simultaneous measurement of 3D deformation fields. Here we present an ESPI system that consists of three sub-interferometers for simultaneous measurement of all three displacement components and in-plane strain fields. A 3CCD color camera, a specially designed shifting stage, and three lasers with optimal wavelengths are used in this system. The lasers and 3CCD camera provide independent interferograms with different color signals, while the shifting stage allows the sub-interferometers to achieve simultaneous phase shifting. The results of color separation and experimental measurement demonstrate the utility of the system.

Digital image correlation with improved efficiency by pixel selection.

With the increase in digital image correlation (DIC) applications, the computational efficiency of DIC is becoming increasingly important. In previous studies, real-time DIC was realized with a relatively small subset. However, a small subset does not always include sufficient gray gradient information. In this paper, a pixel selection strategy is proposed to improve the computational efficiency of DIC further, allowing a real-time deformation measurement with a large subset. Within the subset, zero weight is assigned to unreliable pixels as a way of pursuing maximum efficiency. The modulus of the local intensity gradient vector of each pixel in the reference image is used as the criterion for reliability. Numerical and real experiments conducted to validate the feasibility and effectiveness of the strategy showed that the computational speed of DIC could be improved about 2 times.

Panoramic dual-directional shearography assisted by a bi-mirror.

A panoramic dual-directional shearography system is proposed to simultaneously determine out-of-plane deformation derivatives in two directions and globally inspect the object to be tested. A dichroic filter (DF), a 3CCD camera, and dual-wavelength light are used in the proposed shearography configuration. The dual-wavelength light coupled with the corresponding imaging sensors of the 3CCD camera provides independent color signals and shearograms. Through adjustment of the tilted stereo-angle of the DF, which offers a second wavelength-dependent measurement, an additional independent image-shearing can be introduced into the setup. The auxiliary bi-mirror surrounding the object helps to fully illuminate the object surface and capture it in a single shot. Theoretical analysis and experimental results demonstrated the utility of the system.

Shape measurement with modified phase-shift lateral shearing interferometry illumination and radial basis function.

Three-dimensional shapes of objects were evaluated with modified phase-shift lateral shearing interferometry illumination and radial basis function. A simple optical system was developed to create the fringe pattern based on the Murty interferometer. The phase shift was generated only by moving a plane-parallel plate along an in-plane parallel direction. A novel moving radial basis function method was presented to improve the quality of fringe patterns. And the proper calculation window size was given based on numerical simulation. Three-dimensional shapes of two kinds of objects were determined to verify the feasibility and effectiveness of the proposed method, and the reconstructed height distributions were in good accordance with the referenced data.

Real-time 3D digital image correlation method and its application in human pulse monitoring.

In industrial measurements and online monitoring, full-field and high-efficiency deformation analysis has been increasingly important and highly demanded in recent years. In this paper, a fast three-dimensional digital image correlation (3D-DIC) method was proposed to implement real-time measurement. Two improvements were suggested to accelerate the computation speed without sacrificing the accuracy. First, an efficient inverse compositional Gauss-Newton (IC-GN) algorithm was developed to avoid redundant computation. Moreover, a seed point-based parallel method was extended for 3D-DIC to achieve parallel computation and faster convergence speed. The detailed process of the real-time measurement using the proposed method was also introduced. Benefiting from the efficient IC-GN algorithm and parallel processing software we developed, full-field, real-time 3D deformation monitoring was realized at a frame rate of 10 frames/s with resolution of 5000 points per frame. For validation, the displacement field of a four-point bending beam was determined by the real-time 3D-DIC. As an application, the real-time human pulse diagnosis was also performed based on the presented technique. Experimental results verify that the proposed real-time 3D-DIC is practicable and effective for traditional Chinese medicine.

Survival analysis of a stochastic impulsive single-species population model with migration driven by environmental toxicant.

Considering the influence of environmental toxicant on population migration between patches, we propose and study a stochastic impulsive single-species population model with migration driven by environmental toxicant in this paper. We first discuss the existence and uniqueness of global positive solutions of the model by constructing the Lyapunov function. Then, we obtain sufficient conditions for extinction, stochastic persistence and persistence in the mean of the single-species population. Finally, we present some numerical simulations to illustrate our results. These results provide insights for the conservation and management of species in polluted environments.

Modelling and analysis of periodic impulsive releases of the Nilaparvata lugens infected with wStri-Wolbachia.

In this paper, we formulate a population suppression model and a population replacement model with periodic impulsive releases of Nilaparvata lugens infected with wStri. The conditions for the stability of wild-N.lugens-eradication periodic solution of two systems are obtained by applying the Floquet theorem and comparison theorem. And the sufficient conditions for the persistence in the mean of wild N.lugens are also given. In addition, the sufficient conditions for the extinction and persistence of the wild N.lugens in the subsystem without wLug are also obtained. Finally, we give numerical analysis which shows that increasing the release amount or decreasing the release period are beneficial for controlling the wild N.lugens, and the efficiency of population replacement strategy in controlling wild populations is higher than that of population suppression strategy under the same release conditions.

Defect Detection of Pipeline Inner Surface Based on Coaxial Digital Image Correlation with Hypercentric Lens.

A coaxial dual-camera digital image correlation system using a hypercentric lens was proposed to determine the defect position in the inner wall of a pipeline under loads. Compared with the traditional dual-camera system, this system ensures that both cameras can capture a 360-degree panoramic image in the same position. Herein, the imaging principle of the system was introduced in detail. In addition, the effectiveness and accuracy of the proposed method were verified through verification and application experiments.

Designed for the enhancement of structure mechanostability and strength: Suture-serrate margins of bivalve shells.

Through biological evolution, bivalve mollusks developed shells to improve the utilization of metabolic energy and provide protection against external threats. In addition to the mechanical optimization of the microstructure, the design of the macroscopic shape of a bivalve shell naturally becomes a potential approach to achieving the aforementioned purposes. While the functions of some features of mollusk shells have been studied, the role of the suture-serrate margins, a common morphology of bivalve shell edges, in the global mechanical behaviors of bivalve shells requires further exploration. Here, we present how the serrate margins contribute to the global mechanical properties of bivalve shells. The results of the compression tests employed on a typical bivalve, M. mercenaria, showed that the complete bivalve shells with suture-serrate margins perform better in terms of strength and work to fracture than those without the margins under the same conditions (dry and wet). The primary failure types observed during compression reveal that the failure mechanisms of valve shells are dependent on the suture-serrate margin morphology and water content. Using numerical simulations, the mechanical functions of the suture-serrate margins were demonstrated. Specifically, serrate margins provide mutual resistance by "locking" complementary valves to redistribute and eliminate stress concentrations around pre-existing defects, thereby enhancing the mechanostability and strength of the entire structure.

Camera array-based digital image correlation for high-resolution strain measurement.

Digital image correlation (DIC) is a well-known technique for non-contact, non-destructive, full-field deformation measurement in experimental solid mechanics. Although DIC has been widely used in science and engineering, the resolution of strain measurement with DIC is limited by imaging resolution and is much lower than that obtained with a strain gauge. To achieve a breakthrough in strain measurement using DIC, a camera array-based DIC method is proposed herein for high-resolution strain measurement. Twenty-five industrial cameras were assembled into a plane array, with each camera capturing a part of the specimen. A novel calibration-based image stitching method is proposed and was applied to these images and their corresponding displacement fields. The strain field was then calculated based on the stitched displacement fields. The use of the camera array greatly improved the measurement spatial resolution of DIC and made high-resolution strain measurement possible. Both static error analysis and four point-bending experiments were performed to demonstrate the feasibility and effectiveness of the proposed method, and a full-field strain resolution of 10 µ ε was achieved.

Attachment and localization of human norovirus and animal caliciviruses in fresh produce.

Fresh produce is a high risk food for human norovirus (NoV) contamination. To help control this pathogen in fresh produce, a better understanding of the interaction of human NoV and fresh produce needs to be established. In this study the attachment of human NoV and animal caliciviruses (murine norovirus, MNV-1; Tulane virus, TV) to fresh produce was evaluated, using both visualization and viral enumeration techniques. It was found that a human NoV GII.4 strain attached efficiently to the Romaine lettuce leaves and roots and green onion shoots, and that washing with PBS or 200 ppm of chlorine removed less than 0.4 log of viral RNA copies from the tissues. In contrast, TV and MNV-1 bound more efficiently to Romaine lettuce leaves than to the roots, and simple washing removed less than 1 log of viruses from the lettuce leaves and 1-4 log PFU of viruses from roots. Subsequently, the location of virus particles in fresh produce was visualized using a fluorescence-based Quantum Dots (Q-Dots) assay and confocal microscopy. It was found that human NoV virus-like particles (VLPs), TV, and MNV-1 associated with the surface of Romaine lettuce and were found aggregating in and around the stomata. In green onions, human NoV VLPs were found between the cells of the epidermis and cell walls of both the shoots and roots. However, TV and MNV-1 were found to be covering the surface of the epidermal cells in both the shoots and roots of green onions. Collectively, these results demonstrate that (i) washing with 200 ppm chlorine is ineffective in removing human NoV from fresh produce; and (ii) different viruses vary in their localization patterns to different varieties of fresh produce.