Mixed order robust adaptive control for general linear time invariant systems

We provide a solution to the adaptive control problem of an unknown linear system of a given derivation order, using a reference model or desired poles defined in a possibly different derivation order and employing continuous adjustment of parameters ruled by possibly another different derivation order. To this purpose, we present an extension for the fractional settings of the Bezout’s lemma and gradient steepest descent adjustment. We analyze both the direct and indirect approaches to adaptive control. We discuss some robustness advantages/disadvantages of the fractional adjustment of parameters in comparison with the integer one and, through simulations, the possibility to define optimal derivation order controllers.     

Technological dependence and the failure of educational institutions to support development

Academics, foundations and international agencies concerned with development have repeatedly pointed out the failure of educational institutions to support economic development in underdeveloped countries, particularly in providing the occupational skills and research knowledge in science and technology required by the productive sectors of the economy. The causal factors of this failure have been attributed to institutional deficiencies and traditionalism of backward societies where ‘desk’ jobs and independent professions enjoy higher esteem than technology-related occupations.This paper argues that such educational patterns are rooted in the structures of dependency of the underdeveloped countries. First, employment is concentrated in the non-productive services sector of the economy where desk jobs abound. Second, dependent industrialization entails the predominance of external linkages of industry to developed countries, and technological dependency both in its organic and intellectual components. Industry in underdeveloped countries does not carry out the more complex technological operations of the production cycle or research and development activities for new technology, both of which are done in developed countries. In the absence of this activity, educational institutions cannot ‘learn’ and keep abreast of the modern technological knowledge and processes required for jobs in industry.     

Kinematics used by world class tennis players to produce high-velocity serves

The purpose of this study was to quantify ranges and speeds of movement, from shoulder external rotation to ball impact, in the tennis service actions of world class players. Two electronically synchronised 200 Hz video cameras were used to record 20 tennis players during singles competition at the Sydney 2000 Olympic games. Three-dimensional motion of 20 landmarks on each player and racquet were manually digitized. Based upon the mean values for this group, the elbow flexed to 104 degrees and the upper arm rotated into 172 degrees of shoulder external rotation as the front knee extended. From this cocked position, there was a rapid sequence of segment rotations. The order of maximum angular velocities was trunk tilt (280 degrees/s), upper torso rotation (870 degrees/s), pelvis rotation (440 degrees/s), elbow extension (1510 degrees/s), wrist flexion (1950 degrees/s), and shoulder internal rotation. Shoulder internal rotation was greater for males (2420 degrees/s) than females (1370 degrees/s), which may be related to the faster ball velocity produced by the males (50.8 m/s) than the females (41.5 m/s). Although both genders produced segment rotations in the same order, maximum upper torso velocity occurred earlier for females (0.075 s before impact) than for males (0.058 s). At impact, the trunk was tilted 48 degrees above horizontal, the arm was abducted 101 degrees and the elbow, wrist, and lead knee were slightly flexed. Male and female players should be trained to develop the kinematics measured in this study in order to produce effective high-velocity serves.     

Kinematic and kinetic comparisons between American and Korean professional baseball pitchers

The purpose of this study was to quantify and compare kinematic, temporal, and kinetic characteristics of American and Korean professional pitchers in order to investigate differences in pitching mechanics, performance, and injury risks among two different cultures and populations of baseball pitchers. Eleven American and eight Korean healthy professional baseball pitchers threw multiple fastball pitches off an indoor throwing mound positioned at regulation distance from home plate. A Motion Analysis three-dimensional automatic digitizing system was used to collect 200 Hz video data from four electronically synchronized cameras. Twenty kinematic, six temporal, and 11 kinetic variables were analyzed at lead foot contact, during the arm cocking and arm acceleration phases, at ball release, and during the arm deceleration phase. A radar gun was used to quantify ball velocity. At lead foot contact, the American pitchers had significantly greater horizontal abduction of the throwing shoulder, while Korean pitchers exhibited significantly greater abduction and external rotation of the throwing shoulder. During arm cocking, the American pitchers displayed significantly greater maximum shoulder external rotation and maximum pelvis angular velocity. At the instant of ball release, the American pitchers had significantly greater forward trunk tilt and ball velocity and significantly less knee flexion, which help explain why the American pitchers had 10% greater ball velocity compared to the Korean pitchers. The American pitchers had significantly greater maximum shoulder internal rotation torque and maximum elbow varus torque during arm cocking, significantly greater elbow flexion torque during arm acceleration, and significantly greater shoulder and elbow proximal forces during arm deceleration. While greater shoulder and elbow forces and torques generated in the American pitchers helped generate greater ball velocity for the American group, these greater kinetics may predispose this group to a higher risk of shoulder and elbow injuries.     

Radical student participation: lessons from an urban government primary school in Tigray,Ethiopia

Recent policies in Ethiopia put students at the heart of school improvement through structures for peer leadership and school-level consultation, evaluation and decision-making. This article draws on an ethnographic study of a government school in Tigray, Ethiopia, to explore how the participation and influence of students is achieved and mediated by structures and processes in school. Three key contexts of student participation are explored: positions of peer leadership (monitor, ‘one-to-five’ network leader); public evaluation sessions (gim gima); and the Parent Student Teacher Association (PSTA). Recommendations are made for sharing and strengthening democratic practices and for future research.     

DNA-library assembly programmed by on-demand nano-liter droplets from a custom microfluidic chip

Nanoscale synthetic biology can benefit from programmable nanoliter-scale processing of DNA in microfluidic chips if they are interfaced effectively to biochemical arrays such as microwell plates. Whereas active microvalve chips require complex fabrication and operation, we show here how a passive and readily fabricated microchip can be employed for customizable nanoliter scale pipetting and reaction control involving DNA. This recently developed passive microfluidic device, supporting nanoliter scale combinatorial droplet generation and mixing, is here used to generate a DNA test library with one member per droplet exported to addressed locations on microwell plates. Standard DNA assembly techniques, such as Gibson assembly, compatible with isothermal on-chip operation, are employed and checked using off-chip PCR and assembly PCR. The control of output droplet sequences and mixing performance was verified using dyes and fluorescently labeled DNA solutions, both on-chip and in external capillary channels. Gel electrophoresis of products and DNA sequencing were employed to further verify controlled combination and functional enzymatic assembly. The scalability of the results to larger DNA libraries is also addressed by combinatorial input expansion using sequential injection plugs from a multiwell plate. Hence, the paper establishes a proof of principle of the production of functional combinatorial mixtures at the nanoliter scale for one sequence per well DNA libraries.     

Metabolic time-course response after resistance exercise: A metabolomics approach

This study analysed the time course of the global metabolic acute response after resistance exercise (RE), with the use of proton nuclear magnetic resonance (¹H NMR) spectroscopy. Ten young healthy males performed 4 sets of 10 repetitions at 70% of one-repetition maximum in the leg press and knee extension exercises and had the serum metabolome assessed at 5, 15, 30 and 60 min post-RE. Measurements were also performed 1 h earlier and immediately before the exercises, as an attempt to characterise each participant’s serum metabolome at rest. One-way ANOVA was applied and the significance level was set at P ≤ 0.05. RE promoted an increase in 2-hydroxybutyrate, 2-oxoisocaproate, 3-hydroxyisobutyrate, alanine, hypoxanthine, lactate, pyruvate and succinate concentrations. However, isoleucine, leucine, lysine, ornithine and valine had their concentrations decreased post-RE compared with at rest. This is the first study to show significant changes in serum concentration of metabolites such as 2-oxoisocaproate, 2-hydroxybutyrate, 3-hydroxyisobutyrate, lysine, hypoxanthine and pyruvate post-RE, attesting metabolomics as an interesting approach to advance in the understanding of global RE-induced metabolic changes. Moreover, the present data could influence the time point of blood collection in the future studies that aims to investigate metabolism and exercise.     

信息伦理学的本体论基础

文章首先对信息伦理学的悠久历史作了简单回顾。信息伦理学起源于米歇尔·佛科特(Michel FoucauIt)所分析的希腊语概念“自由演说”或言论自由。关于信息伦理学的最新概念尤其与20世纪随着计算机技术和因特网的发展而出现的各种问题密切相关,它包括大众媒体、图书馆学、信息科学以及商业等领域的伦理问题。从广义上说,信息伦理学概念涉及所有可能现象的数字重建,从而导致与数字本体论相关的种种问题。作者根据海德格尔关于本体论与形而上学关系的观点,认为本体论与“存在”本身有关,它不仅仅与形而上学讨论的主题即生物的生存有关。本文将海德格尔的理论和乔治·斯宾赛·布朗(George Spencer Brown)、高特路·甫瑞(Gottlob Frege)、尼克拉斯·鲁曼(Niklas Luhmann)等学者的学说相提并论,同时加以比较。用佛科特的专业术语来说,本体论是形而上学的尴尬困境。从本体论的角度探讨信息伦理学的基础,其首要目的是质疑数字本体论的形而上学的奢望。数字本体论被认为是当今对“存在”的普遍理解。作者把人类存在作为一种与万物存在即“无标记空间”相关的伦理关系加以分析,在此基础上探讨一些数字技术的挑战,并着重分析数字代理人的道德状况。作者据理论证,信息伦理学不仅仅涉及与佛劳瑞德(Floridi)所提到的“信息领域”相关的伦理问题。文章将这种观点与佛劳瑞德提出的关于信息伦理学基础以及数码代理人道德状态的论点进行对比分析。文章认为,简化论者把人体作为数字数据的观点忽视了数字本体论的局限性,抛弃了伦理定位的基础。最后,文章探讨了同“数字分隔”相关的问题以及信息伦理学跨文化的方方面面,并提出了长期和短期的研究设想。