Visual control of cursorial prey pursuit by tiger beetles (Cicindelidae)

Target detection poses problems for moving animals, such as tiger beetles, that track targets visually. The pursuer's movements degrade target image contrast and induce reafferent image movement that confounds continuous detection of prey. In nature, beetles pursue prey discontinuously with several iterations of stop-and-go running. The beetle's dynamics were analyzed by filming pursuits of prey or experimenter-controlled dummies. Durations of stops are inversely related to prey visual angular velocity; as the prey image moves between neighboring ommatidial fields, the beetle relocalizes it and renews running. During subsequent runs, translation and rotation depend upon prey visual angular velocity and position, respectively, seen during the previous stop. The beetle runs, then stops, while prey continues moving. After two to three iterations of stop-and-go the beetle catches its prey, suggesting open-loop control of running. Computational model simulations produce good qualitative spatio-temporal fit with actual pursuits. However, when pursuing prey dummies, beetles track continuously and quickly follow changes in target position, suggesting closed-loop control using a position-sensitive servo mechanism. Differences between these types of pursuit control system are discussed with respect to limitations in signal detection, particularly spatio-temporal contrast, that may force beetles to use an open-loop system. Accepted: 7 April 1997     

Bionic Mosaic Method of Panoramic Image Based on Compound Eye of Fly

To satisfy the requirements of real-time and high quality mosaics,a bionic compound eye visual system was designed by simulating the visual mechanism of a fly compound eye.Several CCD cameras were used in this system to imitate the small eyes of a compound eye.Based on the optical analysis of this system,a direct panoramic image mosaic algorithm was proposed.Several sub-images were collected by the bionic compound eye visual system,and then the system obtained the overlapping proportions of these sub-images and cut the overlap sections of the neighboring images.Thus,a panoramic image with a large field of view was directly mosaicked,which expanded the field and guaranteed the high resolution.The experimental results show that the time consumed by the direct mosaic algorithm is only 2.2％ of that by the traditional image mosaic algorithm while guaranteeing mosaic quality.Furthermore,the proposed method effectively solved the problem of misalignment of the mosaic image and eliminated mosaic cracks as a result of the illumination factor and other factors.This method has better real-time properties compared to other methods.     

Motion Control in Saccade and Smooth Pursuit for Bionic Eye Based on Three-dimensional Coordinates

Saccade and smooth pursuit are two important functions of human eye.In order to enable bionic eye to imitate the two functions,a control method that implements saccade and smooth pursuit based on the three-dimensional coordinates of target is proposed.An optimal observation position is defined for bionic eye based on three-dimensional coordinates.A kind of motion planning method with high accuracy is developed.The motion parameters of stepper motor consisting of angle acceleration and turning time are computed according to the position deviation,the target's angular velocity and the stepper motor's current angular velocity in motion planning.The motors are controlled with the motion parameters moving to given position with desired angular velocity in schedule time.The experimental results show that the bionic eye can move to optimal observation positions in 0.6 s from initial location and the accuracy of 3D coordinates is improved.In addition,the bionic eye can track a target within the error of less than 20 pixels based on three-dimensional coordinates.It is verified that saccade and smooth pursuit of bionic eye based on three-dimensional coordinates are feasible.     

On the Online Detection of Monotonic Trends in Time Series

The online detection of a monotonic trend in a time series with a time‐varying mean is an important task in medical applications like intensive care monitoring, that is rendered difficult by autocorrelations. Statistical control charts designed for industrial processes are not adequate as they typically rely on a fixed target value, and many detection rules assume a trend to be linear or neglect autocorrelations. We report our experience with the online detection of slow monotonic trends. Our approach is based on a moving time window, and time‐varying autocorrelations are estimated online using parametric assumptions. The performance of versions of this approach is investigated in a simulation study. We find that shrinkage estimation of the time‐varying mean improves the results. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

织物电极的皮肤-电极接触阻抗测量方法分析

随着可穿戴式健康监测技术的发展,新型心电传感器-织物电极成为人们关注的热点,本文对织物电极的皮肤-电极接触阻抗测量方法进行了综述。首先介绍了织物电极的概念,分析了织物电极的皮肤-电极电化学界面、皮肤-电极电化学界面的等效电路和简化电路模型,得出了皮肤-电极接触阻抗的计算公式;其次,将皮肤-电极接触阻抗的测量方法归纳为直接测量法、参比测量法和模拟皮肤测量法三类,讨论了它们的测量原理和优缺点。本文认为需将模拟皮肤测量法和真实皮肤测量法有机结合,才能有效评价织物电极的阻抗特性,为织物电极的性能评价和心电信号采集电路的设计提供重要依据。最后,本文对织物电极待解决的问题进行了分析讨论。     

A Biological Coupling Extension Model and Coupling Element Identification

Extenics is a newly developed interdisciplinary subject combining mathematics, philosophy and engineering. It providesuseful formalized qualitative tools and quantitative tools for solving contradictory problems. In this paper, extension theory isintroduced briefly and the primary applications of this theory and methods in bionic engineering research are discussed. Theextension model of biological coupling functional system is established. In order to identify the primary and secondary sequencingof coupling elements, the Extension Analytic Hierarchy Process (EAHP) was adopted to analyze the contribution ofeach coupling element to the coupling functional system. Thus, the influence weight factor of each coupling element can bedetermined, so as to provide a new approach for solving primary and secondary sequencing problem of coupling elements in aquantitative way, and facilitate the subsequent bionic coupling study.     

Supervised Neural Q_learning based Motion Control for Bionic Underwater Robots

Bionic underwater robots have been a hot research area in recent years. The motion control methods for a kind of bionic underwater robot with two undulating fins are discussed in this paper. The equations of motion for the bionic underwater robot are described. To apply the reinforcement learning to the actual robot control, a Supervised Neural Q_learning (SNQL) algorithm is put forward. This algorithm is based on conventional Q_learning algorithm, but has three remarkable distinctions: (1) using a feedforward neural network to approximate the Q_function table; (2) adopting a learning sample database to speed up learning and improve the stability of learning system; (3) introducing a supervised control in the earlier stage of learning for safety and to speed up learning again. Experiments of swimming straightforward are carried out with SNQL algorithm. Results indicate that the SNQL algorithm is more effective than pure neural Q_learning or supervised control. It is a feasible approach to figure out the motion control for bionic underwater robots.     

DNA传感器研究进展

本文概述了当前生物传感器的研究特点以及发展ＤＮＡ生物传感器的迫切性;从不同角度阐述了ＤＮＡ生物传感器的概念和研究内容;着重讨论了ＤＮＡ生物传感器的研究现状和发展趋势。文中分别对ＤＮＡ光生物传感器和ＤＮＡ压电晶体生物传感器的基本原理、特点、研究进展及存在的问题进行了分析与说明。进而,对我国ＤＮＡ生物传感器研究存在的差距和发展前景进行了简要论述。     

An Ant Colony Optimization Based Dimension Reduction Method for High-Dimensional Datasets

In this paper, a bionic optimization algorithm based dimension reduction method named Ant Colony Optimization -Selection (ACO-S) is proposed for high-dimensional datasets. Because microarray datasets comprise tens of thousands of features (genes), they are usually used to test the dimension reduction techniques. ACO-S consists of two stages in which two well-known ACO algorithms, namely ant system and ant colony system, are utilized to seek for genes, respectively. In the first stage, a modified ant system is used to filter the nonsignificant genes from high-dimensional space, and a number of promising genes are reserved in the next step. In the second stage, an improved ant colony system is applied to gene selection. In order to enhance the search ability of ACOs, we propose a method for calculating priori available heuristic information and design a fuzzy logic controller to dynamically adjust the number of ants in ant colony system. Furthermore, we devise another fuzzy logic controller to tune the parameter (q₀) in ant colony system. We evaluate the performance of ACO-S on five microarray datasets, which have dimensions varying from 7129 to 12000. We also compare the performance of ACO-S with the results obtained from four existing well-known bionic optimization algorithms. The comparison results show that ACO-S has a notable ability to generate a gene subset with the smallest size and salient features while yielding high classification accuracy. The comparative results generated by ACO-S adopting different classifiers are also given. The proposed method is shown to be a promising and effective tool for mining high-dimension data and mobile robot navigation.     

溶酶体检测在海洋污染监测中的应用研究进展

溶酶体(lysosome)是真核细胞内重要的细胞器.近年来随着对溶酶体结构和功能研究的深入,溶酶体被认为是亚细胞水平上的有毒物质的靶点,在国外已广泛应用于海洋污染监测.本文概述了溶酶体标志酶、溶酶体 自噬系统和溶酶体膜的生物学特性,在此基础上介绍了利用溶酶体检测技术进行海洋污染监测的原理和方法.双壳贝类消化腺和鱼类肝脏最适于作为溶酶体检测的敏感器官;采用溶酶体膜稳定性测定(LMS)、溶酶体中性红保留时间测定(NRRT)、溶酶体形态测量(MM)、溶酶体标志酶免疫组化测定(Ih)和电镜(EM)观察等技术,能够指示海洋污染状况,因此溶酶体可作为生物标志物监测海洋环境污染.文中还分析了溶酶体检测的优缺点以及应注意问题,对其应用前景进行了展望.     

核酸试纸条检测方法研究进展*

凝胶电泳、实时荧光PCR等常规核酸检测方法存在操作繁琐、设备昂贵、反应时间长等局限性。随着核酸检测市场规模的大幅提升,常规检测方法已无法满足临床诊断、检验检疫的需求。核酸试纸条(nucleic acid detection strip,NADS)是一种新兴的核酸检测方法,具有灵敏度高、操作便捷、结果可视化、成本低且耗时短等优势,在基础研究与临床诊断等领域受到广泛关注。综述近年来NADS的检测方法及研究进展,系统总结该技术的原理、应用及临床潜在转化价值,以期为NADS的进一步开发、利用提供借鉴。     

Pursuit and prediction in the tracking of moving food by a teleost fish (Acanthaluteres spilomelanurus).

1. The path, eye and body movements of a teleost fish (the leatherjacket Acanthaluteres spilomelanurus) approaching and taking food were measured by cinematography. 2. Fixation of the food by movement of the eyes is an invariable feature of the approach. The eyes then remain aligned with the target while the body moves forward and round to bring the mouth to the food. 3. When pursuing pieces of food moving vertically at constant velocity through the water these fish normally trace out the pathway that can be calculated by assuming the fish aims constantly at the food. Predictive pathways that imply anticipation of the point of intersection with the food are not regularly seen. 4. Deviations from pursuit occur sporadically, usually in the direction of a predictive path, particularly when the fish approach falling food from below. 5. The geometry of the situation suggests that predictive paths may sometimes be generated if the alignment of eye and body during the pursuit of moving food can be delayed. In approaches from below this may be because forward movement of the fish would tend to stabilize the image of the falling food in the retina. 6. We suggest that a simple linked control system using both eye and body movements to fixate retinal images will on occasions generate predictive pathways without any need for the central nervous system to calculate them in advance.     

Differential control of light-dark adaptation in the ocelli and compound eyes of Triatoma infestans

The adaptation to light of compound eyes in insects has been extensively documented and their adaptive role is well understood. Much less attention has been paid, however, to the control of ocelli sensitivity, a study which could help us to understand the functional role of these simple eyes. We analyzed the dynamic changes in the distribution of screening pigments which occur in the ocelli of the haematophagous bug, Triatoma infestans, when the insects are subjected either to light/dark cycles (LD), to constant darkness (DD) or constant light (LL). We then compared these changes with those occurring in the compound eyes of the same individuals and found that, while compound eyes are subject to the control of an endogenous circadian clock, the adaptation of the ocelli is entirely dependent on environmental illumination. In addition, we have observed that environmental temperature is not involved in the control of screening pigments in either ocelli or compound eyes as a direct stimulus, nor as a Zeitgeber. The existence of a differential control in the components of the dual visual system represents an adaptive advantage in the adjustment of visual sensitivity in insects exposed to quick changes in lighting conditions in their natural habitat. We discuss the implications of our findings with regards to the biology of triatomines and with respect to the general understanding the functional role of insect ocelli.     

蜜蜂复眼的视觉通路研究进展

视觉通路的研究在神经科学、 仿生应用和医学治疗上都具有十分重要的意义。西方蜜蜂Apis mellifera作为神经生物学研究的重要模式生物已被广泛地应用于视觉通路的研究。蜜蜂的视觉器官包括1对复眼和3只单眼, 复眼是形成视觉的主要感觉器官。视叶是蜜蜂传递和处理视觉信息的主要神经构造, 它包括视神经节层、 视髓质层、 视小叶和前视结节4个等级的神经纤维网。复杂的视觉信息在经过大脑的各级神经时被分离, 以许多空间隔离的并行连续的视觉通路传递和加工, 然后汇集到高级脑中枢, 部分甚至与其他感觉模态的信息相整合, 最终输出有效信息来调控蜜蜂的各种行为。本文按照信息在视叶中逐级传递的顺序对蜜蜂复眼的视觉通路研究进展进行综述。     

Locus-aware decomposition of gene trees with respect to polytomous species trees

Background

Horizontal gene transfer (HGT), a process of acquisition and fixation of foreign genetic material, is an important biological phenomenon. Several approaches to HGT inference have been proposed. However, most of them either rely on approximate, non-phylogenetic methods or on the tree reconciliation, which is computationally intensive and sensitive to parameter values.

Results

We investigate the locus tree inference problem as a possible alternative that combines the advantages of both approaches. We present several algorithms to solve the problem in the parsimony framework. We introduce a novel tree mapping, which allows us to obtain a heuristic solution to the problems of locus tree inference and duplication classification.

Conclusions

Our approach allows for faster comparisons of gene and species trees and improves known algorithms for duplication inference in the presence of polytomies in the species trees. We have implemented our algorithms in a software tool available at https://github.com/mciach/LocusTreeInference.

     

Schema generation in recurrent neural nets for intercepting a moving target

The grasping of a moving object requires the development of a motor strategy to anticipate the trajectory of the target and to compute an optimal course of interception. During the performance of perception-action cycles, a preprogrammed prototypical movement trajectory, a motor schema, may highly reduce the control load. Subjects were asked to hit a target that was moving along a circular path by means of a cursor. Randomized initial target positions and velocities were detected in the periphery of the eyes, resulting in a saccade toward the target. Even when the target disappeared, the eyes followed the target’s anticipated course. The Gestalt of the trajectories was dependent on target velocity. The prediction capability of the motor schema was investigated by varying the visibility range of cursor and target. Motor schemata were determined to be of limited precision, and therefore visual feedback was continuously required to intercept the moving target. To intercept a target, the motor schema caused the hand to aim ahead and to adapt to the target trajectory. The control of cursor velocity determined the point of interception. From a modeling point of view, a neural network was developed that allowed the implementation of a motor schema interacting with feedback control in an iterative manner. The neural net of the Wilson type consists of an excitation-diffusion layer allowing the generation of a moving bubble. This activation bubble runs down an eye-centered motor schema and causes a planar arm model to move toward the target. A bubble provides local integration and straightening of the trajectory during repetitive moves. The schema adapts to task demands by learning and serves as forward controller. On the basis of these model considerations the principal problem of embedding motor schemata in generalized control strategies is discussed.     

DNA芯片技术在食品病原体检测中的应用

病原体的存在,尤其是食品中的病原体,给人类健康带来了威胁。DNA芯片技术是一种非常有效的病原体检测工具,具有众多传统检测方法所不具备的优势,受到广泛关注。我们简要论述了DNA芯片在细菌病原体、寄生虫、病毒病原体、微生物耐药性等的检测中的应用,并进一步综述了DNA芯片技术在食品检测中存在的问题、解决方法及发展方向。     

Spatial facilitation by a high-performance dragonfly target-detecting neuron

Many animals visualize and track small moving targets at long distances-be they prey, approaching predators or conspecifics. Insects are an excellent model system for investigating the neural mechanisms that have evolved for this challenging task. Specialized small target motion detector (STMD) neurons in the optic lobes of the insect brain respond strongly even when the target size is below the resolution limit of the eye. Many STMDs also respond robustly to small targets against complex stationary or moving backgrounds. We hypothesized that this requires a complex mechanism to avoid breakthrough responses by background features, and yet to adequately amplify the weak signal of tiny targets. We compared responses of dragonfly STMD neurons to small targets that begin moving within the receptive field with responses to targets that approach the same location along longer trajectories. We find that responses along longer trajectories are strongly facilitated by a mechanism that builds up slowly over several hundred milliseconds. This allows the neurons to give sustained responses to continuous target motion, thus providing a possible explanation for their extraordinary sensitivity.     

核酸层析法转基因快速检测体系的建立及应用

随着我国转基因研究及产业化进程提速,转基因检测的重要性日益凸显,因而快速、高效的分子检测新方法的研发具有重要的生产实践及科研意义。在转基因检测中,常规PCR技术具有检测范围广的特点,但较为费时费力,且对实验条件要求较高;而胶体金蛋白试纸法检测方便、快捷,但可检范围窄。基于此,建立了一套基于核酸层析法快速转基因检测的方法体系。将经液氨研磨后的样品通过一管法提取DNA后直接进行PCR扩增,再将PCR扩增产物滴加到胶体金检测卡上,通过直接观察胶体金卡条显色状况进行结果判别。此方法最终检验出玉米内参基因ZSSⅡB及Zein、大豆内参基因SPS、水稻内参基因Lectin,转基因元件启动子CaMV35S及终止子NOS,以及抗虫基因Cry1Ab/1Ac、抗除草剂基因Bar、Pat、CP4-EPSPS及选择标记基因NPTⅡ、Pmi等外源基因;并成功检出特异性转基因事件Mir604及Bt11。研究获得的核酸层析检测方法具有灵敏度高、省时省力且对检测条件要求低等优点,集PCR法与蛋白试纸检测法二者优势于一身,可广泛应用于转基因产品的精确快速检测,为我国转基因生物安全监管提供了良好的技术支撑。     

A desk-top computer coupled fermentation system for the study of microbial processes: Description and some applications

The configuration and hardware components of a desk-top computer coupled system for bench-top bioreactors are described. Examples of on-line acquisition of several directly accessible environmental process parameters and computations of directly inaccessible state variables are presented. The system described offers great advantages in experiments for establishing sophisticated control algorithms and for studying the physiological behaviour of microbial populations.