Computerized detection and segmentation of mitochondria on electron microscope images

Mitochondrial function plays an important role in the regulation of cellular life and death, including disease states. Disturbance in mitochondrial function and distribution can be accompanied by significant morphological alterations. Electron microscopy tomography (EMT) is a powerful technique to study the 3D structure of mitochondria, but the automatic detection and segmentation of mitochondria in EMT volumes has been challenging due to the presence of subcellular structures and imaging artifacts. Therefore, the interpretation, measurement and analysis of mitochondrial distribution and features have been time consuming, and development of specialized software tools is very important for high-throughput analyses needed to expedite the myriad studies on cellular events. Typically, mitochondrial EMT volumes are segmented manually using special software tools. Automatic contour extraction on large images with multiple mitochondria and many other subcellular structures is still an unaddressed problem. The purpose of this work is to develop computer algorithms to detect and segment both fully and partially seen mitochondria on electron microscopy images. The detection method relies on mitochondria's approximately elliptical shape and double membrane boundary. Initial detection results are first refined using active contours. Then, our seed point selection method automatically selects reliable seed points along the contour, and segmentation is finalized by automatically incorporating a live-wire graph search algorithm between these seed points. In our evaluations on four images containing multiple mitochondria, 52 ellipses are detected among which 42 are true and 10 are false detections. After false ellipses are eliminated manually, 14 out of 15 fully seen mitochondria and 4 out of 7 partially seen mitochondria are successfully detected. When compared with the segmentation of a trained reader, 91% Dice similarity coefficient was achieved with an average 4.9 nm boundary error.     

Mechanical properties and repair bond strength of polymer-based CAD/CAM restorative materials

Information on the mechanical properties and repairability of computer-aided design/computer-aided manufacturing (CAD/CAM) blocks is scarce. Five CAD/CAM blocks with similar indications were evaluated, including four resin nanoceramics, one polymer-infiltrated ceramic network (PICN), and one feldspathic ceramic. CAD/CAM blocks were sectioned into 4 mm × 1.2 mm × 13 mm bars for flexural strength (FS), and 4 mm thick blocks were prepared for elastic modulus (EM), nanohardness (NH), and microshear bond strength (µSBS) testing. FS of the CAD/CAM blocks was determined using a three-point bending test, whereas EM and NH values were measured using a nanoindenter. The reparability of the tested block materials was determined by the µSBS test. One-way ANOVA was conducted for FS, EM, NH, and µSBS followed by Tukey's pairwise comparison (α < 0.05). FS ranged from 115 to 207 MPa, EM from 8.21 to 44 GPa, NH from 0.76 to 7.24, and µSBS from 24.9 to 30.6 MPa. The findings of the present study revealed that resin nanoceramic blocks exhibited higher FS values than PICN and feldspathic ceramic, and they have acceptable mechanical properties for the fabrication of single-unit restorations according to the ISO 6872:2008. Furthermore, all CAD/CAM blocks tested can be successfully repaired regarding their recommended repair protocol.     

Improvements in microstructural,mechanical, and biocompatibility properties of nano-sized hydroxyapatites doped with yttrium and fluoride

Hydroxyapatite was doped with Y³⁺ (2.5, 5 and 7.5 mol%) and F⁻ (2.5 mol%) ions (2.5YFHA, 5YFHA, 7.5YFHA, respectively) to compare its structural and mechanical properties and cellular response with pure-hydroxyapatite. No second phases were observed by X-ray diffraction spectra of 2.5YFHA. Doped hydroxyapatites had F⁻ bonds in addition to OH⁻ bonds. Hydroxyapatites sintered at 900 and 1100 °C were in nano-size. 7.5YFHA sintered at 1300 °C had the highest microhardness value. 2.5YFHA sintered at 1100 °C had the highest fracture toughness value. MTT viability assays showed high cell attachments on 2.5YFHA. Cell proliferation on 2.5YFHA and 5YFHA sintered at 1100 and 1300 °C was comparable with the control after 5-day culture. The highest ALP production and calcium deposition were observed on all hydroxyapatites sintered at 1100 °C. 2.5YFHA sintered at 1100 °C can be an alternative for hydroxyapatite in orthopedic applications.     

Unethical computer using behavior scale: A study of reliability and validity on Turkish university students

This study was carried out in a Turkish university with 216 undergraduate students of computer technology as respondents. The study aimed to develop a scale (UECUBS) to determine the unethical computer use behavior. A factor analysis of the related items revealed that the factors were can be divided under five headings; intellectual property, social impact, safety and quality, net integrity and information integrity.     

Investigation of thermoluminescence properties of metal oxide doped lithium triborate

In this study, lithium triborate (LiB₃O₅) doped with different metal oxides were investigated to explore its thermoluminescence properties. Solid-state reaction method was employed for the synthesis of the desired materials. The formation of the produced phases was confirmed by Powder X-Ray Diffraction (XRD), Infrared (IR), Differential Thermal Analysis (DTA) and Scanning Electron Microscopy (SEM) examinations. It was found that, CuO and Al₂O₃ doped lithium triborate samples exhibit very significant thermoluminescence glow curves to be promising dosimetric material.     

Downlink throughput optimization for wideband CDMA systems

This article examines the optimization of throughput in a wireless system. A mathematical model is outlined for a cellular wideband CDMA system. In practical cases, where the maximum transmission power is constrained, power control may not be possible. Self-interference limits the total deliverable rate. It is shown that by optimally allocating bit-rate using a dynamic programming algorithm, a higher bit-rate can be delivered within the same power constraint. Simulation results show on average a 20% increase in total delivered rate can be achieved.     

Analysis and design of a stabilized fly ash as pavement base material

The main objective of this study is to utilize a class F fly ash as base material in road pavements. Since class F fly ashes do not manifest desirable engineering properties for this purpose, it was decided to stabilize the material with cement. Fly ash may be utilized with or without aggregate as a pavement layer. It should be noted that, in this research only aggregate free stabilized mixtures (fly ash and cement only) were used since the aim was to utilize high volumes of this waste material. Cement content in the stabilized, laboratory prepared samples were between 2%, 4%, 8%, and 10% by total weight. Initially, Texas triaxial test was carried out to justify the suitability of the fly ash as pavement material. Then, mechanical tests were performed to obtain the fundamental properties of the cement stabilized material in order to analyze the pavement structure. Under repeated wheel loading, fatigue cracking is the primary mode of failure of stabilized materials in which cracks initiate due to the repeated tensile stresses. Utilizing an accelerated full scale road test data for the fatigue performance of cement stabilized fly ash and performing a mechanistic-empirical design procedure, required layer thickness for different lives were obtained for different amount of cement content.