Human muscle spindles act as forward sensory models.

Modern theories of motor control incorporate forward models that combine sensory information and motor commands to predict future sensory states. Such models circumvent unavoidable neural delays associated with on-line feedback control. Here we show that signals in human muscle spindle afferents during unconstrained wrist and finger movements predict future kinematic states of their parent muscle. Specifically, we show that the discharges of type Ia afferents are best correlated with the velocity of length changes in their parent muscles approximately 100-160 ms in the future and that their discharges vary depending on motor sequences in a way that cannot be explained by the state of their parent muscle alone. We therefore conclude that muscle spindles can act as "forward sensory models": they are affected both by the current state of their parent muscle and by efferent (fusimotor) control, and their discharges represent future kinematic states. If this conjecture is correct, then sensorimotor learning implies learning how to control not only the skeletal muscles but also the fusimotor system.

Effects of periphyton grown on bamboo substrates on growth and production of Indian major carp, rohu (Label rohita Ham.)

The effects of periphyton, grown on bamboo substrates, on growth and production of Indian major carp, rohu, Labeo rohita (Hamilton), were studied in 10 ponds during July to October '95 at the Bangladesh Agricultural University, Mymensingh. Five ponds were provided with bamboo substrates (treatment I) and the rests without bamboo substrates (treatment II). It was revealed that there had been no discernible difference in the water quality parameters between treatments. A large number of plankton (30 genera) showed periphytic nature and colonized on the bamboo substrates. The growth and production of fish was significantly (p<0.05) higher in the ponds with bamboo substrates as compared to the ponds without substrates. The net production of rohu in treatment I was about 1.7 times higher than that of treatment II. Fish production was as much as 1899 kg/ha over a culture period of 4 months in the periphyton-based production system.

Motor learning of novel dynamics is not represented in a single global coordinate system: evaluation of mixed coordinate representations and local learning.

Successful motor performance requires the ability to adapt motor commands to task dynamics. A central question in movement neuroscience is how these dynamics are represented. Although it is widely assumed that dynamics (e.g., force fields) are represented in intrinsic, joint-based coordinates (Shadmehr R, Mussa-Ivaldi FA. J Neurosci 14: 3208-3224, 1994), recent evidence has questioned this proposal. Here we reexamine the representation of dynamics in two experiments. By testing generalization following changes in shoulder, elbow, or wrist configurations, the first experiment tested for extrinsic, intrinsic, or object-centered representations. No single coordinate frame accounted for the pattern of generalization. Rather, generalization patterns were better accounted for by a mixture of representations or by models that assumed local learning and graded, decaying generalization. A second experiment, in which we replicated the design of an influential study that had suggested encoding in intrinsic coordinates (Shadmehr and Mussa-Ivaldi 1994), yielded similar results. That is, we could not find evidence that dynamics are represented in a single coordinate system. Taken together, our experiments suggest that internal models do not employ a single coordinate system when generalizing and may well be represented as a mixture of coordinate systems, as a single system with local learning, or both.

LOCAL BENDING OF THIN FILM ON VISCOUS LAYER

Effects of deposition layer position and number/density on local bending of a thin film are systematically investigated. Because the deposition layer interacts with the thin film at the interface and there is an offset between the thin film neutral surface and the interface, the deposition layer generates not only axial stress but also bending moment. The bending moment induces an instant out-of-plane deflection of the thin film, which may or may not cause the so-called local bending. The deposition layer is modeled as a local stressor, whose location and density are demonstrated to be vital to the occurrence of local bending. The thin film rests on a viscous layer, which is governed by the Navier-Stokes equation and behaves like an elastic foundation to exert transverse forces on the thin film. The unknown feature of the axial constraint force makes the governing equation highly nonlinear even for the small deflection case. The constraint force and film transverse deflection are solved iteratively through the governing equation and the displacement constraint equation of immovable edges. This research shows that in some special cases, the deposition density increase does not necessarily reduce the local bending. By comparing the thin film deflections of different deposition numbers and positions, we also present the guideline of strengthening or suppressing the local bending.

Isochiral form II of syndiotactic polypropylene produced by epitaxial crystallization

Epitaxial crystallization of syndiotactic polypropylene (sPP) on 2-quinoxalinol (2-Quin) yields, in the lower part of the crystallization range, the less common and metastable form II based on the packing of isochiral helices, rather than the stable antichiral form I. The contact plane is (110)(II). Form II exits only as a thin layer (< 50 nm) near the substrate surface. During further growth away from the surface, a transition takes place to the disordered form I, observed in "conventional" thin film growth. The epitaxial relationship rests only partly on dimensional matching with the chain axis repeat distance (which would be valid for both forms I and II) and on interchain distances. Whereas a better dimensional match would be achieved with form I, selection of the isochiral form II results from better correspondence of the surface topographies of the deposit (110)(II) sPP and substrate 2-Quin (001) contact faces.

基于小波变换的机器人腕力传感器滤波算法

在对机器人腕力传感器信号特点分析基础上,提出了应用小波变换对腕力传感器信号进行滤波的方法,讨论了小波滤波算法,研究了机器人腕力传感器信号滤波方案,并针对抛光机器人作业实验数据进行滤波。仿真实验表明方法有效。

基于CAN总线的力传感器与机器人控制器通讯设计

研磨机器人系统中,研磨头与工件的接触力是保证加工精度,进行机器人力控制的一个重要因 素。采用 CAN 通讯可以确保力传感器准确、及时地把力信息传送给控制器进行力控制。本文 给出了6维腕力传感器与机器人控制器通讯的硬件结构,制定了可靠的通讯协议,实现了力信 息的正确读取,为研磨机器人控制系统获得可靠的力信息提供了一种新的解决方案。

LW-1型机器人重复位姿精度检测系统

本文介绍了一种非接触式（ＬＷ－１型）机器人重复位姿精度检测系统．该系统采用电涡流传感器作为位置信息传感器．以这种传感器的检测性能为基础，研究设计了相应的传感器测量结构、数学模型和坐标变换求解方法，使系统技术指标及使用性能达到了检测机器人重复位姿精度的实用要求．该系统具有鲁棒性强、设计合理、结构简单、造价低廉等特点，可以满足我国现阶段在机器人学研究和机器人开发应用方面的需求

PUMA760切割作业力与位置混合控制

本文介绍在 PUMA760 上实现了的切割作业控制系统。我们在 PUMA760 控制系统中引进了力传感器信号,加入了力控制算法,通过调整机器人手部位置,控制机器人与环境物体间的相互作用力。在 VAL 系统中加入了根据传感器信号动作的指令,实现了一种机器人力与位置的混合控制。用扩充后的 VAL 系统编程,成功地使 PUMA760完成了多种材料的切割作业。

A experiência de vida e as expectativas futuras de famílias beneficiárias de RSI

Dissertação de Mestrado apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Psicologia, especialização em Psicologia Clínica e da Saúde.

Sobrecargas posturais

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

A construção ideográfica nas relações internacionais portuguesas 1945-1960

Tese apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em Ciências Sociais, especialidade em Relações Internacionais

Occupational lead neurotoxicity: A behavioural and electrophysiological evaluation. study design and year one results.

To evaluate the effects of chronic lead exposure on the nervous system in adults, a set of neurobehavioural and electrophysiological tests was administered to 99 lead exposed foundry employees and 61 unexposed workers. Current and past blood lead concentrations were used to estimate the degree of lead absorption; all previous blood lead concentrations had been less than or equal to 90 micrograms/100 ml. Characteristic signs (such as wrist extensor weakness) or symptoms (such as colic) of lead poisoning were not seen. Sensory conduction in the sural nerve was not affected. By contrast, various neurobehavioural functions deteriorated with increasing lead burden. Workers with blood lead concentrations between 40 and 60 micrograms/100 ml showed impaired performance on tests of verbal concept formation, visual/motor performance, memory, and mood. Thus impairment in central nervous system function in lead exposed adults occurred in the absence of peripheral nervous system derangement and increased in severity with increasing lead dose.

A Biomechanical Model of Human Oculomotor Plant Kinematics Based Upon Geometric Algebra

A biomechanical model of the human oculomotor plant kinematics in 3-D as a function of muscle length changes is presented. It can represent a range of alternative interpretations of the data as a function of one parameter. The model is free from such deficits as singularities and the nesting of axes found in alternative formulations such as the spherical wrist (Paul, l98l). The equations of motion are defined on a quaternion based representation of eye rotations and are compact atnd computationally efficient.

Leadership, fairness and gender: a practitioner's perspective

This Portfolio of Exploration outlines the course of learning by a practitioner on a personal leadership journey. It constructs a functional examination of ideas around leadership. It explores the belief system which underpins leadership practice and it also explores to what extent the increased participation of women can lead to a qualitatively different type of leadership. Different models of leadership are explored to find the model which can best fit with the author’s perception of leadership. The Women’s Intercultural Leadership Model is discussed. This model conceptualises leadership as the envisioning of oneself and others as potential leaders. It seeks to promote that recognition whilst at the same time encouraging personal transformation. The promotion of a values based leadership is examined. The value of fairness is examined as an element of functional leadership. The extent to which increasing the number of women in leadership can lead to a qualitatively different type of leadership is explored. Drucker’s assertion that every practice rests on theory is used to unearth the underlying assumptions of this reflective practitioner doctorate. Kegan’s Theory of Adult Mental Development and Subject-Object separation is used to explicitly examine knowledge construction. Myers Briggs Type Indicator (MBTI) and Assumption/Commitment/Behaviour/Outcome (ACBO) template are used to promote practice change.