Statistical characteristics of landmark-based localization performance

Landmark-based localization is a prevalent method to obtain the position information of objects, such as autonomous robots, in industries. This study investigated the performance characteristics of landmark-based localization based on the popular multilateration algorithm from new perspectives. Two performance metrics were used, namely, accuracy and precision, which are defined as the mean and standard deviation of root mean squared error over the entire localization region. The general formulations for the two metrics were obtained, and the computation was accomplished by Monte Carlo simulation. The simulation was performed under a simplified localization configuration, and the following system factors were systematically studied, namely, landmark layout, landmark number, target location distribution, and ranging error type. The quality of landmark layout was, for the first time, quantitatively assessed. Optimal layout can be obtained by minimization of the localization accuracy and precision values with regard to the quality index. It was found that the index represented by the area of polygon enclosed by the landmarks is an excellent measure of layout quality. Also, the improvement of localization performance can be achieved by distributing landmarks more evenly, using more landmarks, placing the target closer to the center of localization region, or reducing the ranging errors. Furthermore, it was also demonstrated that the findings in simulation are generally confirmed by the experimental results using active radio-frequency identification (RFID) devices.     

Mathematical classification of tight junction protein images

We present the rationale for the development of mathematical features used for classification of images stained for selected tight junction proteins. The project examined localization of zonula occludens‐1, claudin‐1 and F‐actin in a model epithelium, Madin–Darby canine kidney II cells. Cytochalasin D exposure was used to perturb junctional localization by actin cytoskeleton disruption. Mathematical features were extracted from images to reliably reveal characteristic information of the pattern of protein localization. Features, such as neighbourhood standard deviation, gradient of pixel intensity measurement and conditional probability, provided meaningful information to classify complex image sets. The newly developed mathematical features were used as input to train a neural network that provided a robust method of individual image classification. The ability for researchers to make determinations concerning image classification while minimizing human bias is an important advancement for the field of tight junction cellular biology.     

Fine structural analysis of the epithelial cells in the hepatopancreas of Palaemonetes argentinus (Crustacea, Decapoda, Caridea) in intermoult.

The aim of this study is to describe the ultrastructure of the hepatopancreas of P. argentinus in intermoult. P. argentinus hepatopancreas was studied using standard TEM techniques. Each tubule consists of four cellular types: E (embryonic), F (fibrillar), R (resorptive) and B (blister like). E-cells have embryonic features and some of them were found in mitosis. F, R and B cells possess an apical brush border. F-cells have a central or basal nucleus, a conspicuous RER, and dilated Golgi cisternae. R cells show a polar organization of organelles in three areas: apical, with numerous mitochondria and sER tubules, a central area with the nucleus and RER, and a basal area containing a sER-like tubule system and mitochondria. B-cells were observed at different stages of their life cycle. In an early differentiation stage they comprise an apical endocytotic complex and Golgi vesicles. The fusion of endocytotic and Golgi vesicles originates subapical vacuoles. During maturation, a big central vacuole is formed by coalescence of subapical vacuoles. The central vacuole is eliminated by holocrine secretion. The ultrastructure suggests that F-cells synthesize proteins, R-cells storage nutrients and B-cells have a secretory or excretory function, and confirms the independent origin of F, B and R cells from the embryonic cells.     

基于概率方法的多微型机器人分布式定位

针对常见的微小型机器人群体定位中单纯依赖外部彩色视觉图像信息以及定位精度较差的问题,提出了一种基于概率方法的多微型机器人分布式定位方法。该方法利用部分可观Markov过程,将外部视觉信息和机器人个体的驱动信息融合,从而提高了定位精度。方法基于分布式形式出现,并且仅需要外部视觉传感器提供灰度图像,从而提高了多机器人系统的可扩展性。     

线粒体ATP合成酶复合体分离纯化的方法学研究与探讨

科研工作者们在过去的50年前赴后继的工作中深入研究了ATP合成酶的功能,并努力尝试解析该酶的空间结构以其能够从结构基础上对ATP合成酶的催化机理进行阐明;但蛋白的纯化工作却一直是困扰研究顺利进展的最大障碍.蛋白的纯化技术是与特定阶段科技发展及科研工作者思维模式的直接反应,因而是一门不断发展的艺术.高纯度的ATP合成酶及其亚基是研究酶结构与催化机理的基础和关键,文章综合半个世纪以来ATP合成酶研究发展,提出了一条较为完备的ATP合成酶提取与纯化的方法路线,并对FO-ATPase部分亚基c的纯化方法进行了重点介绍.     

对厚壁压力容器超声波周向检测工艺的分析

通过对厚壁压力容器几何尺寸的分析，选择恰当的超声波K值探头，对整个壁体进行100％的扫查，并结合准确的定位计算，从而制定正确的超声波周向检测工艺。     

运用拓扑优化的结构损伤定位

以结构共振频率和结构某点的反共振频率为基础,对拓扑优化中的渐进结构优化法应用于结构损伤定位的可行性进行了研究。基于结构共振频率和反共振频率的灵敏度分析,建立了损伤定位的数学模型,提出了利用渐进结构优化法进行损伤定位的策略。针对单一和多处损伤结构,分别给出了损伤定位的数值算例,对不同的损伤结构予以讨论,并准确识别出了损伤位置。结果表明,在已经测得结构损伤前后共振频率和反共振频率的基础上,渐进结构优化法能够在整个结构区域内寻找损伤点,有较好的搜寻效果。     

拟南芥悬浮细胞中ERG437蛋白的细胞定位的初步观察

近来在大肠杆菌中新发现的Era蛋白（E.coli ras-like protein）是一类新的GTP结合蛋白,研究表明Era蛋白参与调节细胞分裂、细胞周期以及部分细胞代谢过程。植物中相关研究报道尚少,推测ERG蛋白可能定位在线粒体,并且与种子的正常发育相关。本实验通过构建植物表达载体初步观察了ERG437蛋白在拟南芥悬浮细胞中的定位情况,同时利用CoxⅣ蛋白初步观察到绝大部分ERG437蛋白定位于线粒体。     

Cytochemical localization of ATP-ase activity in plant root cells

ATP-ase activity in root-tip cells of Zea mays has been localized by using a lead phosphate precipitation procedure. Activity is associated with the plasmalemma, nucleus, mitochondria, Golgi bodies, vacuoles and endoplasmic reticulum al though the relativeactivities vary in different regions of the root. The localization of surface ATP-ase is compared with that of surface β-glycerophosphatase and the results discussed in relation to the possible role of ATP-ase in ion transport.     

Metabolic state dependent preservation of cells by fixatives for electron microscopy

The preservation of mitochondria, cytoplasmic vacuoles and cytoplasm by various fixatives after various pretreatments of ethothelial heart cells from Xenopus laevis tadpoles in tissue culture was investigated. The study was based on phase contrast cinemicrographic recordings and on qualitative and quantitative observations with the electron microscope. Three fixatives were used: 3% glutaraldehyde in phosphate buffer, followed by 1% osmium tetroxide postfixation, fixation only with 1% osmium tetroxide in phosphate buffer and the fixing medium according to Dalton. Cells were either not treated or pretreated for 20 min: 10 microM FCCP (Carbonylcyanide-p-trifluoromethoxy-phenylhydrazone) or 4 mM KCN. The superiority of glutaraldehyde was exemplified by its very rapid action, good preservation of cytoplasm, vacuoles, and mitochondria. It was the only medium which maintained an electron density of the mithochondria matrix. In both of the other fixatives swelling of mitochondria and coagulated appearance of cytoplasm (in phase contrast) was more pronounced in cells pretreated with metabolic inhibitors than in controls. Observations with the light microscope have been confirmed by morphometry of electron micrographs of mitochondria. The relation of matrix space to intracristal space is changed in opposite directions after glutaraldehyde and after the Dalton-type fixation. The results indicate a higher sensitivity against fixation artifacts in cells under pathological conditions than normal cells.     

Ultrastructure and reproduction behaviour of single CHO-K1 cells exposed to near infrared femtosecond laser pulses

In the present work, the authors investigated ultrastructural changes as well as the reproduction behaviour of preselected single CHO-K1 cells exposed to 170 femtosecond laser pulses at different power output levels in comparison with cells outside the illumination volume. The ultrashort laser pulses were provided by an 80 MHz Ti:sapphire laser at 780 nm. The cells were scanned ten times with a scan rate of 1/16 s(-1). Single CHO-K1 cells exposed to low mean power of 2 mW revealed no significant changes in ultrastructure after laser exposure. In some cases, changes of mitochondria with slight disordering of cristae were found. Cytoplasm was filled with vesicles that seemed to be released from Golgi stacks. Cells irradiated with higher powers demonstrated more dramatic changes in ultrastructure. A considerable number of swollen mitochondria in conjunction with loss of cristae was observed. The main event of mitochondrial changes was the formation of electron dense bodies in the mitochondrial matrix. In addition, lumen of endoplasmatic reticulum was enlarged. Highest applied mean laser power of 12.5 mW lead to complete destruction of mitochondria and their transformation to electron dense structures containing membrane material. Compared with cell targets irradiated with 2 mW mean power, the release of vesicles from Golgi stacks seemed to be rather moderate. Cells localised outside the laser beam revealed no ultrastructural changes. Low mean laser power at 2 mW was unable to impair the reproduction behaviour of CHO-K1 cells. At higher laser power output levels, CHO-K1 cells started to delay cell division. At 12.5 mW, no cell division occurred. The obtained results may be helpful in recommending parameters for safe femtosecond laser microscopy of living specimens.     

Autofluorescence of living cells

We have investigated the autofluorescence of viable mammalian cells (DU-145 and V79) with a confocal laser scanning microscope equipped with a UV laser. Our aim was to investigate the autofluorescence dependence on different treatments in mitochondria and lysosomes by using different reagents and to improve the confocal laser scanning microscope image quality by deconvolution. The following conclusions were drawn from the results: (1) not all of the autofluorescence comes from mitochondria; (2) one can significantly affect the signal which comes from the mitochondria; (3) the other organelles involved are probably lysosomes; (4) it is harder to affect the autofluorescence signal from the lysosomes than that from the mitochondria, and (5) deconvoluted autofluorescence images provide better information than undeconvoluted ones.     

通用小型汽油机进排气系统试验台设计与应用

针对国内通用小型汽油机生产中出现的问题,为提高汽油机进排气系统的流通能力和降低整机排放,设计了用于通用小型汽油机进排气系统的稳流试验台,对稳流试验台用于汽油机的研究、零部件检验和整机质量控制的功能做了介绍,以1P68F汽油机为例,对汽油机的进排气系统进行了初步稳流试验,对试验结果进行了分析,结果表明通用小型汽油机进排气系统零部件流动性能普遍较差。按内燃机流动特性进行优化设计、处理好压铸件工艺要求与流通性能的矛盾,改进通用小型汽油机进排气系统零部件质量,能提高我国通用小型汽油机的性能和产品技术水平。     

Cryofracture of paraffin-embedded heart muscle cells.

A comparative study of internal cellular structures of the sheep ventricular myocardium has been conducted by scanning electron microscopy (SEM) and by transmission electron microscopy (TEM). Access to the cell interior for three-dimensional studies was obtained by cryofracturing paraffin-embedded tissue frozen in liquid nitrogen. For accurate localization of structures of special interest thick paraffin sections were examined in the light microscope (LM). Based on the information gained, it was possible to fracture the block in a desired plane. The fracturing was carried out by a light blow to a precooled scalpel held against the surface of the block, which was immersed in liquid nitrogen. After thawing and deparaffinizing at room temperature in several baths of xylene, the tissue pieces were critical point dried using CO2. As xylene was found to be miscible with CO2, it also served as an intermediate fluid. This method resulted in good preservation fo the myofibrils, mitochondria, sarcoplasmic reticulum and transverse tubules (T-tubules), which was confirmed by TEM studies of conventionally prepared tissue and of tissue originally prepared for SEM.     

Three dimensional rendering of the mitochondrial sheath morphogenesis during mouse spermiogenesis

In the middle piece of mouse sperm tail, the idea of the mitochondria wrapping in a sinistral (left-handed) double helical structure was generally accepted. In the existing model, mitochondria aligned in four longitudinal rows (stage 1) and twisted dextrally (right-handed) (stage 2) and began to stagger, where opposing rows of mitochondria contacted each other to form a sinistral double helix (stage 3), finally, the end-on touching mitochondria further elongated to their mature length (stage 4). However, in this model, mitochondria need to shift a long distance and reposition themselves. Since no gaps have been found in mitochondrial sheath, repositioning of most mitochondria along the middle piece is unlikely to happen. Therefore, we reapproached the questions through three-dimensional rendering to provide a new model for mitochondrial sheath formation. In our proposed model, four dextrally arranged spherical mitochondrial arrays were considered stage 1 (resembles stage 2 of the old model). In stage 2 (resembles stage 3 of the old model), a critical difference was found that pairs of mitochondria from the opposing arrays formed ring-like structures instead of a sinistral double helix. In stage 3, which was not observed in the old model, mitochondria staggered in a specific pattern to form the sinistral double helix. In stage 4, mitochondria elongated from crescent-shaped to rod-shaped structures. The new model proposed here would allow each mitochondrion to stay at where they attached first and elongate laterally from two directions to reach their final double helical structure without unreasonable great distance shift along the outer dense fibers.     

Quantitative subcellular imaging of boron compounds in individual mitotic and interphase human glioblastoma cells with imaging secondary ion mass spectrometry (SIMS)

Boron measurements at subcellular scale are essential in boron neutron capture therapy (BNCT) of cancer as the nuclear localization of boron‐10 atoms can enhance the effectiveness of killing individual tumour cells. Since tumours contain a heterogeneous population of cells in interphase as well as in the M phase (mitotic division) of the cell cycle, it is important to evaluate the subcellular distribution of boron in both phases. In this work, the secondary ion mass spectrometry (SIMS) based imaging technique of ion microscopy was used to quantitatively image boron from two BNCT agents, clinically used p‐boronophenylalanine (BPA) and 3‐[4‐(o‐carboran‐1‐yl)butyl]thymidine (N4), in mitotic metaphase and interphase human glioblastoma T98G cells. N4 belongs to a class of experimental BNCT agents, designated 3‐carboranyl thymidine analogues (3CTAs), which presumably accumulate selectively in cancer cells due to a process referred to as kinase‐mediated trapping (KMT). The cells were exposed to BPA for 1 h and N4 for 2 h. A CAMECA IMS‐3f SIMS ion microscope instrument capable of producing isotopic images with 500 nm spatial resolution was used in the study. Observations were made in cryogenically prepared fast frozen, and freeze‐fractured, freeze‐dried cells. Three discernible subcellular regions were studied: the nucleus, a characteristic mitochondria‐rich perinuclear cytoplasmic region, and the remaining cytoplasm in interphase T98G cells. In metaphase cells, the chromosomes and the cytoplasm were studied for boron localization. Intracellular concentrations of potassium and sodium also were measured in each cell in which the subcellular boron concentrations were imaged. Since the healthy cells maintain a K/Na ratio of approximately 10 due to the presence of Na‐K‐ATPase in the plasma membrane of mammalian cells, these measurements provided validation for cryogenic sample preparation and indicated the analysis healthy, well preserved cells. The BPA‐treated interphase cells revealed significantly lower concentrations of boron in the perinuclear mitochondria‐rich cytoplasmic region as compared to the remaining cytoplasm and the nucleus, which were not significantly different from each other. In contrast, the BPA‐treated metaphase cells revealed significantly lower concentration of boron in their chromosomes than cytoplasm. In addition, the cytoplasm of metaphase cells contained significantly less boron than the cytoplasm of interphase cells. These observations provide valuable information on the reduced uptake of boron from BPA in mitotic cells for BPA‐mediated BNCT. SIMS observations on N4 revealed that boron was distributed throughout the interphase and mitotic cells, including the chromosomes. The presence of boron in chromosomes of metaphase cells treated with N4 is indicative of a possible incorporation of this thymidine analogue into DNA. The 3‐D SIMS imaging approach for the analysis of mitotic cells shown in this work should be equally feasible to the evaluation of other BNCT agents.     

Electron microscopic radioautographic study of RNA synthesis in hepatocyte mitochondria of aging mouse

In order to study the aging changes of intramitochondrial RNA synthesis in mouse hepatocytes, 10 groups of aging mice, each consisting of three individuals (total 30) from fetal day 19 to postnatal month 24 were injected with 3H-uridine, an RNA precursor, sacrificed 1 hour later, and the liver tissues processed for electron microscopic radioautography. On EM radioautograms obtained from each animal the number of mitochondria, the number of labeled mitochondria, and the mitochondrial labeling index labeled with 3H-uridine showing RNA synthesis in each hepatocytes, both mononucleate and binucleate cells, were counted and the averages in respective aging groups were compared. From the results it was demonstrated that the numbers of mitochondria, the numbers of labeled mitochondria, and the labeling indices of intramitochondrial RNA syntheses in both mononucleate and binucleate hepatocytes of mice at various ages increased and decreased according to the age of the animals.     

Computer-assisted three-dimensional reconstruction technology in plant cell image analysis: applications of interactive computer graphics

Sequences of more than 100 serial thin sections were cut of entire generative cells of pollen of Brassica campestris. Using transmission electron micrographs, outlines of the cell nucleus, vacuoles and mitochondria were digitized and stored on disc using the Carl Zeiss-Kontron Videoplan Image Analysis System. The data collected concerned the geometry of cuts and logical collection of cuts into structures, both internal and external. A data translation and surface generation system was established to transfer these data to a VAX-751 computer to establish an interface to the Intergraph's Interactive Graphics Design System (IGDS). Definition of the surfaces is based on the translated boundaries and structural configuration, enabling three-dimensional visualization of: (a) the wireframe model; (b) the overall model with removed hidden lines, including colour or monochrome shading; and (c) the shaded image of the internal structures with superimposed wireframe representation of the external structures.     

The photoreceptive cells of the pineal gland in adult zebrafish (Danio rerio)

The zebrafish pineal gland plays a fundamental role in the regulation of the circadian rhythm through the melatonin secretion. The pinealocytes, also called photoreceptive cells, are considered the morphofunctional unit of pineal gland. In literature, the anatomical features, the cellular characteristics, and the pinealocytes morphology of zebrafish pineal gland have not been previously described in detail. Therefore, this study was undertaken to analyze the structure and ultrastructure, as well as the immunohistochemical profile of the zebrafish pineal gland with particular reference to the pinealocytes. Here, we demonstrated, using RT-PCR, immunohistochemistry and transmission electron microscopy, the expression of the mRNA for rhodopsin in the pineal gland of zebrafish, as well as its cellular localization exclusively in the pinealocytes of adult zebrafish. Moreover, the ultrastructural observations demonstrated that the pinealocytes were constituted by an outer segment with numerous lamellar membranes, an inner segment with many mitochondria, and a basal pole with the synapses. Our results taken together demonstrated a central role of zebrafish pinealocytes in the control of pineal gland functions.