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Operational Principles (operational + principle)
Selected AbstractsSocial status determines sexual phenotype in the bi-directional sex changing bluebanded goby Lythrypnus dalliJOURNAL OF FISH BIOLOGY, Issue 6 2007E. W. Rodgers The behavioural mechanisms and patterns of protandrous sex change in bluebanded gobies Lythrypnus dalli were investigated and compared to the well-described behaviour patterns of protogynous sex change. To do this, unisex groups of males and females were established; behavioural and anatomical changes were recorded over a 42 day period as social status and sexual phenotype were determined. In all cases, social status, rather than the expression of a particular behaviour, accurately predicted final sexual phenotype. Rates of submissive behaviour, but not aggressive behaviour, were predictive of each discrete status class. Multiple individuals changed sex simultaneously if their sexual phenotype and social status were discordant, a novel finding suggesting that once a social hierarchy is established, individuals determined their sexual phenotype, regardless of initial sex, based on a simple operational principle: if subordinate express female, if dominant or not subordinate express male. This work demonstrates that similar mechanisms underlie sex change in both directions in L. dalli and potentially other sex changing species. [source] Urquhart's and Garfield's Laws: The British controversy over their validityJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 9 2001Stephen J. Bensman The British controversy over the validity of Urquhart's and Garfield's Laws during the 1970s constitutes an important episode in the formulation of the probability structure of human knowledge. This controversy took place within the historical context of the convergence of two scientific revolutions,the bibliometric and the biometric,that had been launched in Britain. The preceding decades had witnessed major breakthroughs in understanding the probability distributions underlying the use of human knowledge. Two of the most important of these breakthroughs were the laws posited by Donald J. Urquhart and Eugene Garfield, who played major roles in establishing the institutional bases of the bibliometric revolution. For his part, Urquhart began his realization of S. C. Bradford's concept of a national science library by analyzing the borrowing of journals on interlibrary loan from the Science Museum Library in 1956. He found that 10% of the journals accounted for 80% of the loans and formulated Urquhart's Law, by which the interlibrary use of a journal is a measure of its total use. This law underlay the operations of the National Lending Library for Science and Technology (NLLST), which Urquhart founded. The NLLST became the British Library Lending Division (BLLD) and ultimately the British Library Document Supply Centre (BLDSC). In contrast, Garfield did a study of 1969 journal citations as part of the process of creating the Science Citation Index (SCI), formulating his Law of Concentration, by which the bulk of the information needs in science can be satisfied by a relatively small, multidisciplinary core of journals. This law became the operational principle of the Institute for Scientific Information created by Garfield. A study at the BLLD under Urquhart's successor, Maurice B. Line, found low correlations of NLLST use with SCI citations, and publication of this study started a major controversy, during which both laws were called into question. The study was based on the faulty use of the Spearman rank-correlation coefficient, and the controversy over it was instrumental in causing B. C. Brookes to investigate bibliometric laws as probabilistic phenomena and begin to link the bibliometric with the biometric revolution. This paper concludes with a resolution of the controversy by means of a statistical technique that incorporates Brookes' criticism of the Spearman rank-correlation method and demonstrates the mutual supportiveness of the two laws. [source] Electrochemical Detection for Capillary Electrophoresis Microchips: A ReviewELECTROANALYSIS, Issue 13 2005Joseph Wang Abstract Electrochemistry detection offers considerable promise for capillary-electrophoresis (CE) microchips, with features that include remarkable sensitivity, portability, independence of optical path length or sample turbidity, low cost and power requirements, and high compatibility with modern micromachining technologies. This article highlights key strategies in controlled-potential electrochemical detectors for CE microchip systems, along with recent advances and directions. Subjects covered include the design of the electrochemical detection system, its requirements and operational principles, common electrode materials, isolation from the separation voltage, derivatization reactions, typical applications, and future prospects. It is expected that electrochemical detection will become a powerful tool for CE microchip systems and will lead to the creation of truly portable (and possibly disposable) devices. [source] Neurons with distinctive firing patterns, morphology and distribution in laminae V,VII of the neonatal rat lumbar spinal cordEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Péter Szûcs Abstract It is generally accepted that neurons in the ventral spinal grey matter, a substantial proportion of which can be regarded as constituents of the spinal motor apparatus, receive and integrate synaptic inputs arising from various peripheral, spinal and supraspinal sources. Thus, a profound knowledge concerning the integrative properties of interneurons in the spinal ventral grey matter appears to be essential for a fair understanding of operational principles of spinal motor neural assemblies. Using the whole cell patch clamp configuration in a correlative physiological and morphological experimental approach, here we demonstrate that the intrinsic membrane properties of neurons vary widely in laminae V,VII of the ventral grey matter of the neonatal rat lumbar spinal cord. Based on their firing patterns in response to depolarizing current steps, we have classified the recorded neurons into four categories: ,phasic', ,repetitive', ,single' and ,slow'. Neurons with firing properties characteristic of the ,phasic', ,repetitive' and ,single' cells have previously been reported also in the superficial and deep spinal dorsal horn, but this is the first account in the literature in which ,slow' neurons have been recovered and described in the spinal cord. The physiological heterogeneity in conjunction with the morphological correlation and distribution of neurons argues that different components of motor neural assemblies in the spinal ventral grey matter possess different signal processing characteristics. [source] Is the Open Method of Coordination Appropriate for Organising Activities at European Level in Sensitive Policy Areas?EUROPEAN LAW JOURNAL, Issue 1 2002Caroline de la Porte This article addresses the question of the relevance of the most recent soft policy instrument of the EU, the open method of coordination (OMC), for organising actions at European level in politically sensitive areas. In addition to describing its origins and operational principles, we will compare its application to the areas of employment and social inclusion. Two hypotheses make up the structure of the text. The first is that the discourses produced in the framework of OMC in the areas of employment and social inclusion are broad enough to cater to the different welfare models, but that the changes to be made by the Member States to be in line with the European discourses differ considerably, depending on their welfare state family and their initial situation. The second is that the form of OMC is variable, depending on policy area. Our conclusions confirm both of these hypotheses. [source] A metric for spaceHIPPOCAMPUS, Issue 12 2008Edvard I. Moser Abstract Not all areas of neuronal systems investigation have matured to the stage where computation can be understood at the microcircuit level. In mammals, insights into cortical circuit functions have been obtained for the early stages of sensory systems, where signals can be followed through networks of increasing complexity from the receptors to the primary sensory cortices. These studies have suggested how neurons and neuronal networks extract features from the external world, but how the brain generates its own codes, in the higher-order nonsensory parts of the cortex, has remained deeply mysterious. In this terra incognita, a path was opened by the discovery of grid cells, place-modulated entorhinal neurons whose firing locations define a periodic triangular or hexagonal array covering the entirety of the animal's available environment. This array of firing is maintained in spite of ongoing changes in the animal's speed and direction, suggesting that grid cells are part of the brain's metric for representation of space. Because the crystal-like structure of the firing fields is created within the nervous system itself, grid cells may provide scientists with direct access to some of the most basic operational principles of cortical circuits. © 2008 Wiley-Liss, Inc. [source] | ||||||||||