Extending the depth of field in a compound-eye imaging system with super-resolution reconstruction

Optical device miniaturization is highly desirable in many applications. Direct down-scaling of traditional imaging system is one approach, but the extent to which it can be minimized is limited by the effect of diffraction. Compound-eye imaging system, which utilizes multiple microlenses in image capture is a promising alternative. In this paper, we explore the possibility of an incorporation of phase masks in such a system to extend the depth of field. Simulation experiments are conducted to verify the feasibility of the system. © 2006 IEEE.published_or_final_versio

A total variation regularization based super-resolution reconstruction algorithm for digital video

Super-resolution (SR) reconstruction technique is capable of producing a high-resolution image from a sequence of low-resolution images. In this paper, we study an efficient SR algorithm for digital video. To effectively deal with the intractable problems in SR video reconstruction, such as inevitable motion estimation errors, noise, blurring, missing regions, and compression artifacts, the total variation (TV) regularization is employed in the reconstruction model. We use the fixed-point iteration method and preconditioning techniques to efficiently solve the associated nonlinear Euler-Lagrange equations of the corresponding variational problem in SR. The proposed algorithm has been tested in several cases of motion and degradation. It is also compared with the Laplacian regularization-based SR algorithm and other TV-based SR algorithms. Experimental results are presented to illustrate the effectiveness of the proposed algorithm.£.published_or_final_versio

Reference-free detection of semiconductor assembly defect

This paper aims at developing a novel defect detection algorithm for the semiconductor assembly process by image analysis of a single captured image, without reference to another image during inspection. The integrated circuit (IC) pattern is usually periodic and regular. Therefore, we can implement a classification scheme whereby the regular pattern in the die image is classified as the acceptable circuit pattern and the die defect can be modeled as irregularity on the image. The detection of irregularity in image is thus equivalent to the detection of die defect. We propose a method where the defect detection algorithm first segments the die image into different regions according to the circuit pattern by a set of morphological segmentations with different structuring element sizes. Then, a feature vector, which consists of many image attributes, is calculated for each segmented region. Lastly, the defective region is extracted by the feature vector classification. © 2005 SPIE and IS&T.published_or_final_versio

Deletions within the azoospermia factor subregions of the Y chromosome in Hong Kong Chinese men with severe male-factor infertility: controlled clinical study.

OBJECTIVE: To determine the patterns and the prevalence of microdeletions in the azoospermia factor subregions of the Y chromosome in Hong Kong Chinese men with severe male-factor infertility. DESIGN: Controlled clinical study. SETTING: Reproductive centre of a university teaching hospital, Hong Kong. PARTICIPANTS: Fifty-eight men with severe male-factor infertility who participated in the in vitro fertilisation programme from May 1998 through March 1999, and 46 male volunteers with proven fertility. MAIN OUTCOME MEASURES: Polymerase chain reaction analysis of DNA from peripheral blood lymphocytes using six loci spanning the AZFa, AZFb, and AZFc subregions of the Y chromosome. RESULTS. No microdeletions were detected in the fertile controls or in patients with obstructive azoospermia. Deletions within the AZFc subregion were found in 9% (4/44) of men with non-obstructive azoospermia or severe oligospermia. Neither AZFa nor AZFb deletions were detected in any participants. CONCLUSION: Deletions within the azoospermia factor subregions of the Y chromosome are associated with severe male-factor infertility in Hong Kong Chinese men.published_or_final_versio

"Faith Maturity Scale" for Chinese: A Revision and Construct Validation

Using a large sample of Chinese Christians (n = 2,196), we examined the internal structure, reliability, and validity of the Faith Maturity Scale (FMS). Despite its being developed in North America, and for a mainline Protestant population, the FMS was shown to have validity among non-Western, non-mainline Protestants. There is convergent validity with self-reported religious practices and a belief measure of religiosity. Our analyses also confirmed good construct validity with the Big Five personality dimensions, social axioms, attributional style, and quality of life. FMS remained associated with religious practices and high quality of life after personality was statistically controlled. Findings supported that the Chinese version of the FMS assesses the same theoretical construct as does the original scale and that the distinction between the vertical and horizontal dimensions of faith maturity is meaningful. © 2011 Copyright Taylor and Francis Group, LLC.postprin

Electrostatic Assembly of Multiarm PEG-Based Hydrogels as Extracellular Matrix Mimics: Cell Response in the Presence and Absence of RGD Cell Adhesive Ligands

Synthetic hydrogels have been used widely as extracellular matrix (ECM) mimics due to the ability to control and mimic physical and biochemical cues observed in natural ECM proteins such as collagen, laminin, and fibronectin. Most synthetic hydrogels are formed via covalent bonding resulting in slow gelation which is incompatible with drop-on-demand 3D bioprinting of cells and injectable hydrogels for therapeutic delivery. Herein, we developed an electrostatically crosslinked PEG-based hydrogel system for creating high-throughput 3D in vitro models using synthetic hydrogels to mimic the ECM cancer environment. A 3-arm PEG-based polymer backbone was first modified with either permanent cationic charged moieties (2-(methacryloyloxy)ethyl trimethylammonium) or permanent anionic charged moieties (3-sulfopropyl methacrylate potassium salt). The resulting charged polymers can be conjugated further with various amounts of cell adhesive RGD motifs (0, 25, 75, and 98%) to study the influences of RGD motifs on breast cancer (MCF-7) spheroid formation. Formation, stability, and mechanical properties of hydrogels were tested with, and without, RGD to evaluate the cellular response to material parameters in a 3D environment. The hydrogels can be degraded in the presence of salts at room temperature by breaking the interaction of oppositely charged polymer chains. MCF-7 cells could be released with high viability through brief exposure to NaCl solution. Flow cytometry characterization demonstrated that embedded MCF-7 cells proliferate better in a softer (60 Pa) 3D hydrogel environment compared to those that are stiffer (1160 Pa). As the stiffness increases, the RGD motif plays a role in promoting cell proliferation in the stiffer hydrogel. Flow cytometry characterization demonstrated that embedded MCF-7 cells proliferate better in a softer (60 Pa) 3D hydrogel environment compared to those that are stiffer (1160 Pa). As the stiffness increases, the RGD motif plays a role in promoting cell proliferation in the stiffer hydrogel. Additionally, cell viability was not impacted by the tested hydrogel stiffness range between 60 to 1160 Pa. Taken together, this PEG-based tuneable hydrogel system shows great promise as a 3D ECM mimic of cancer extracellular environments with controllable biophysical and biochemical properties. The ease of gelation and dissolution through salt concentration provides a way to quickly harvest cells for further analysis at any given time of interest without compromising cell viability

PhOTO Zebrafish: A Transgenic Resource for In Vivo Lineage Tracing during Development and Regeneration

Background: Elucidating the complex cell dynamics (divisions, movement, morphological changes, etc.) underlying embryonic development and adult tissue regeneration requires an efficient means to track cells with high fidelity in space and time. To satisfy this criterion, we developed a transgenic zebrafish line, called PhOTO, that allows photoconvertible optical tracking of nuclear and membrane dynamics in vivo. Methodology: PhOTO zebrafish ubiquitously express targeted blue fluorescent protein (FP) Cerulean and photoconvertible FP Dendra2 fusions, allowing for instantaneous, precise targeting and tracking of any number of cells using Dendra2 photoconversion while simultaneously monitoring global cell behavior and morphology. Expression persists through adulthood, making the PhOTO zebrafish an excellent tool for studying tissue regeneration: after tail fin amputation and photoconversion of a ~100µm stripe along the cut area, marked differences seen in how cells contribute to the new tissue give detailed insight into the dynamic process of regeneration. Photoconverted cells that contributed to the regenerate were separated into three distinct populations corresponding to the extent of cell division 7 days after amputation, and a subset of cells that divided the least were organized into an evenly spaced, linear orientation along the length of the newly regenerating fin. Conclusions/Significance: PhOTO zebrafish have wide applicability for lineage tracing at the systems-level in the early embryo as well as in the adult, making them ideal candidate tools for future research in development, traumatic injury and regeneration, cancer progression, and stem cell behavior

Improved Cellular Specificity of Plasmonic Nanobubbles versus Nanoparticles in Heterogeneous Cell Systems

The limited specificity of nanoparticle (NP) uptake by target cells associated with a disease is one of the principal challenges of nanomedicine. Using the threshold mechanism of plasmonic nanobubble (PNB) generation and enhanced accumulation and clustering of gold nanoparticles in target cells, we increased the specificity of PNB generation and detection in target versus non-target cells by more than one order of magnitude compared to the specificity of NP uptake by the same cells. This improved cellular specificity of PNBs was demonstrated in six different cell models representing diverse molecular targets such as epidermal growth factor receptor, CD3 receptor, prostate specific membrane antigen and mucin molecule MUC1. Thus PNBs may be a universal method and nano-agent that overcome the problem of non-specific uptake of NPs by non-target cells and improve the specificity of NP-based diagnostics, therapeutics and theranostics at the cell level