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Modular Structure (modular + structure)
Selected AbstractsVibration signals from the FT joint can induce phase transitions in both directions in motoneuron pools of the stick insect walking systemDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2003Ulrich Bässler Abstract The influence of vibratory signals from the femoral chordotonal organ fCO on the activities of muscles and motoneurons in the three main leg joints of the stick insect leg, i.e., the thoraco,coxal (TC) joint, the coxa,trochanteral (CT) joint, and the femur,tibia (FT) joint, was investigated when the animal was in the active behavioral state. Vibration stimuli induced a switch in motor activity (phase transition), for example, in the FT joint motor activity switched from flexor tibiae to extensor tibiae or vice versa. Similarly, fCO vibration induced phase transitions in both directions between the motoneuron pools of the TC joint and the CT joint. There was no correlation between the directions of phase transition in different joints. Vibration stimuli presented during simultaneous fCO elongation terminated the reflex reversal motor pattern in the FT joint prematurely by activating extensor and inactivating flexor tibiae motoneurons. In legs with freely moving tibia, fCO vibration promoted phase transitions in tibial movement. Furthermore, ground vibration promoted stance,swing transitions as long as the leg was not close to its anterior extreme position during stepping. Our results provide evidence that, in the active behavioral state of the stick insect, vibration signals can access the rhythm generating or bistable networks of the three main leg joints and can promote phase transitions in motor activity in both directions. The results substantiate earlier findings on the modular structure of the single-leg walking pattern generator and indicate a new mechanism of how sensory influence can contribute to the synchronization of phase transitions in adjacent leg joints independent of the walking direction. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 125,138, 2003 [source] A Modular Approach to a New Class of Monodentate Chiral Phosphorus Ligands and Their Application in Enantioselective Copper-Catalysed Conjugate Additions of Diethylzinc to CyclohexenoneEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2004Chiara Monti Abstract A new family of chiral phosphorus ligands (5) for use in enantioselective catalysis have been synthesised. The ligands contain the electron-poor bis(sulfonyl)diazaphospholidine moiety and possess a highly modular structure which is well suited to the synthesis of a library. A small library (23 members) of ligands 5 was prepared and tested in the enantioselective copper-catalysed conjugate addition of diethylzinc to cyclohexenone. Complete conversions were obtained with enantiomeric excesses (ee) of up to 75%. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] THE EVOLUTION OF THE VERTEBRATE ,-GLOBIN GENE PROMOTEREVOLUTION, Issue 2 2002Nadia A. Chuzhanova Abstract Complexity analysis is capable of highlighting those gross evolutionary changes in gene promoter regions (loosely termed "promoter shuffling") that are undetectable by conventional DNA sequence alignment. Complexity analysis was therefore used here to identify the modular components (blocks) of the orthologous ,-globin gene promoter sequences of 22 vertebrate species, from zebrafish to humans. Considerable variation between the ,-globin gene promoters was apparent in terms of block presence/absence, copy number, and relative location. Some sequence blocks appear to be ubiquitous, whereas others are restricted to a specific taxon. Block similarities were also evident between the promoters of the paralogous human ,-like globin genes. It may be inferred that a wide variety of different mutational mechanisms have operated upon the ,-globin gene promoter over evolutionary time. Because these include gross changes such as deletion, duplication, amplification, elongation, contraction, and fusion, as well as the steady accumulation of single base-pair substitutions, it is clear that some redefinition of the term "promoter shuffling" is required. This notwithstanding, and as previously described for the vertebrate growth hormone gene promoter, the modular structure of the ,-globin promoter region and those of its paralogous counterparts have continually been rearranged into new combinations through the alteration, or shuffling, of preexisting blocks. Some of these changes may have had no influence on promoter function, but others could have altered either the level of gene expression or the responsiveness of the promoter to external stimuli. The comparative study of vertebrate ,-globin gene promoter regions described here confirms the generality of the phenomenon of sequence block shuffling and thus supports the view that it could have played an important role in the evolution of differential gene expression. [source] Knowledge acquisition for the development of an upper-body work-related musculoskeletal disorders analysis toolHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 2 2007Isabel Lopes Nunes ERGO_X is a fuzzy expert system that supports workstation ergonomic analysis and provides advice on corrective measures aimed at improving the overall quality of the ergonomic design. ERGO_X was designed in a modular way to make further developments easier and to allow the selection of different ergonomic analysis contexts. The modularity feature mainly is a result of the knowledge base modular structure. Each module was built as a multilevel tree fuzzy relation. This relation reflects the interaction between attributes that are used to evaluate the level of severity of the relevant risk factors that are present at the analyzed workstation. The aim of this study is to address some aspects related to the knowledge acquisition process involved in the development of the ERGO_X knowledge base. In this regard, the author refers to her knowledge engineering activities in the development of a work-related musculoskeletal disorder module. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 149,162, 2007. [source] Open Source Software: Private Provision of a Public GoodJOURNAL OF ECONOMICS & MANAGEMENT STRATEGY, Issue 4 2002Justin Pappas Johnson A simple model of open source software (as typified by the GNU-Linux operating system) is presented. Individual user-programmers decide whether to invest their own effort to develop a software enhancement that will become a public good if so developed. The effect of changing the population size of user-programmers is considered; finite and asymptotic results are given. Welfare results are presented. It is shown that whether development will increase when applications have a modular structure depends on whether the developer base exceeds a critical size. Potential explanations of several stylized facts are given, including why certain useful programs don't get written. [source] Simulation and implementation of a porous silicon reflector for epitaxial silicon solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2008Filip Duerinckx Abstract One of the main challenges in the ongoing development of thin film crystalline silicon solar cells on a supporting silicon substrate is the implementation of a long-wavelength reflector at the interface between the epitaxial layer and the substrate. IMEC has developed such a reflector based on electrochemical anodization of silicon to create a multi-layer porous silicon stack with alternating high and low porosity layers. This innovation results in a 1,2% absolute increase in efficiency for screenprinted epitaxial cells with a record of 13·8%. To reach a better understanding of the reflector and to aid in its continued optimization, several extensive optical simulations have been performed using an in-house-developed optical software programme. This software is written as a Microsoft Excel workbook to make use of its user-friendliness and modular structure. It can handle up to 15 individual dielectric layers and is used to determine the influence of the number and the sequence of the layers on the internal reflection. A sensitivity analysis is also presented. A study of the angle at which the light strikes the reflector shows separate regions in the physical working of the reflector which include a region where the Bragg effect is dominant as well as a region where total internal reflection plays the largest role. The existence of these regions is proved using reflection measurements. Based on these findings, an estimate is made for the achievable current gain with an ideal reflector and the potential of epitaxial silicon solar cells is determined. Copyright © 2008 John Wiley & Sons, Ltd. [source] The ankyrin repeat as molecular architecture for protein recognitionPROTEIN SCIENCE, Issue 6 2004Leila K. Mosavi Abstract The ankyrin repeat is one of the most frequently observed amino acid motifs in protein databases. This protein,protein interaction module is involved in a diverse set of cellular functions, and consequently, defects in ankyrin repeat proteins have been found in a number of human diseases. Recent biophysical, crystallographic, and NMR studies have been used to measure the stability and define the various topological features of this motif in an effort to understand the structural basis of ankyrin repeat-mediated protein,protein interactions. Characterization of the folding and assembly pathways suggests that ankyrin repeat domains generally undergo a two-state folding transition despite their modular structure. Also, the large number of available sequences has allowed the ankyrin repeat to be used as a template for consensus-based protein design. Such projects have been successful in revealing positions responsible for structure and function in the ankyrin repeat as well as creating a potential universal scaffold for molecular recognition. [source] Network modules help the identification of key transport routes, signaling pathways in cellular and other networksANNALEN DER PHYSIK, Issue 12 2009R. Palotai Abstract Complex systems are successfully reduced to interacting elements via the network concept. Transport plays a key role in the survival of networks , for example the specialized signaling cascades of cellular networks filter noise and efficiently adapt the network structure to new stimuli. However, our general understanding of transport mechanisms and signaling pathways in complex systems is yet limited. Here we summarize the key network structures involved in transport, list the solutions available to overloaded systems for relaxing their load and outline a possible method for the computational determination of signaling pathways. We highlight that in addition to hubs, bridges and the network skeleton, the overlapping modular structure is also essential in network transport. Path-lenghts in the module-space of the yeast protein-protein interaction network indicated that module-based paths may cross fewer modular boundaries than shortest paths. Moreover, by locating network elements in the space of overlapping network modules and evaluating their distance in this ,module space', it may be possible to approximate signaling pathways computationally, which, in turn could serve the identification of signaling pathways of complex systems. Our model may be applicable in a wide range of fields including traffic control or drug design. [source] Identification of mouse heart transcriptomic network sensitive to various heart diseasesBIOTECHNOLOGY JOURNAL, Issue 5 2008Seong-Eui Hong Abstract Exploring biological systems from highly complex datasets is an important task for systems biology. The present study examined co-expression dynamics of mouse heart transcriptome by spectral graph clustering (SGC) to identify a heart transcriptomic network. SGC of microarray data produced 17 classified biological conditions (called condition spectrum, CS) and co-expression patterns by generating bi-clusters. The results showed dynamic co-expression patterns with a modular structure enriched in heart-related CS (CS-1 and -13) containing abundant heart-related microarray data. Consequently, a mouse heart transcriptomic network was constructed by clique analysis from the gene clusters exclusively present in the heart-related CS; 31 cliques were used for constructing the network. The participating genes in the network were closely associated with important cardiac functions (e. g., development, lipid and glycogen metabolisms). Online Mendelian Inheritance in Man (OMIM) database indicates that mutations of the genes in the network induced serious heart diseases. Many of the tested genes in the network showed significantly altered gene expression in an animal model of hypertrophy. The results suggest that the present approach is critical for constructing a heart-related transcriptomic network and for deducing important genes involved in the pathogenesis of various heart diseases. [source] Empirical Challenges and Concept Formation in the History of HydrodynamicsCENTAURUS, Issue 3 2008Olivier Darrigol Abstract Although the fundamental equations of hydrodynamics were known at an early stage of its history, this theory long remained irrelevant to most of the practical problems of flow. The advent of a more efficient fluid mechanics in the early twentieth century depended on conceptual schemes that could not be read directly from the basic equations. Attention to concrete problems of flow, rather than purely mathematical deduction or purely intuitive guessing, permitted the gradual introduction of relevant substructures and their ultimate combination in powerful approximation schemes. This history is in part singular, owing to the extreme difficulty of dealing with non-linear systems with infinitely many degrees of freedom. But it is also typical as an illustration of the futility of reducing a physico-mathematical theory to its fundamental equations. Any advanced theory of physics must include an evolving modular structure that plays an essential role in melding the formal with the empirical. [source] Multitasking by Multivalent Circular DNA AptamersCHEMBIOCHEM, Issue 3 2006Daniel A. Di Giusto Abstract Nucleic acid aptamers are finding increasing applications in biology, especially as therapeutic candidates and diagnostic components. An important characteristic in meeting the needs of these applications is improved stability in physiological fluids, which is most often accomplished with chemical modification or unnatural nucleotides. In an alternative approach we have specified the design of a multivalent circular DNA aptamer topology that encompasses a number of properties relevant to nucleic acid therapeutic candidates, especially the ability to multitask by combining different activities together within a modular structure. Improved stability in blood products, greater conformational stability, antidoting by complementary circular antiaptamers, heterovalency, transcription factor decoy activity and minimal unintended effects upon the cellular innate immune response are desirable properties that are described here. Multitasking by circular DNA aptamers could similarly find applications in diagnostics and biomaterials, where the combination of interchangeable modules might generate new functions, such as anticoagulation coupled with reversible cell capture as, described here. These results provide a platform for further exploration of multivalent circular aptamer properties, especially in novel combinations of nucleic acid therapeutic modes. [source] How to evaluate metacognitive functioning in psychotherapy?CLINICAL PSYCHOLOGY AND PSYCHOTHERAPY (AN INTERNATIONAL JOURNAL OF THEORY & PRACTICE), Issue 4 2003The metacognition assessment scale, its applications In this article the authors present a method and a scale for the evaluation of the metacognitive profiles of psychotherapy patients. There will be a description of the metacognitive function and of the alterations that occur to it during treatment. Various hypotheses will then be considered: (1) that the metacognitive function has a modular structure; (2) that for each type of psychopathological condition there is a different metacognitive deficit profile; (3) that to be successful psychotherapy needs to involve an improvement in any deficient metacognitive sub-function. There will then be a presentation of the Metacognition Assessment Scale (MAS) for the assessment of metacognitive deficits during psychotherapy. We shall then describe the first results we have on the application of the scale. Finally there will be an analysis of two patients suffering from Personality Disorders and a demonstration of what metacognitive deficit profile each one has and how it is modified over the course of psychotherapy treatment. The article ends with a discussion of the hypotheses made at the start in the light of the results that have emerged.,Copyright © 2003 John Wiley & Sons, Ltd. [source] New method to measure minisatellite variant repeat variation in population genetic studiesAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2002M. Brión The classical analysis of minisatellite variant repeat (MVR) variation using modular structures is limited by the lack of knowledge of the mutational process involved in the evolution of most of the minisatellites. In this study a new method to measure MVR variation and to calculate genetic distances using MVR codes is proposed. The method is based on the statistical similarity of MVR patterns and considers the complete variability of the minisatellite, enabling meaningful comparisons of closely related populations. As an example, the method has been applied to analyze variation in MSY1 (DYF155S1) in five sets of data from European and North African populations. Am. J. Hum. Biol. 14:421,428, 2002. [source] Superspace description of the homologous series Ga2O3(ZnO)mACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2010Yuichi Michiue A unified description for the structures of the homologous series Ga2O3(ZnO)m, gallium zinc oxide, is presented using the superspace formalism. The structures were treated as a compositely modulated structure consisting of two subsystems. One is constructed with metal ions and the other with O ions. The ideal model is given, in which the displacive modulations of ions are well described by the zigzag function with large amplitudes. Alternative settings are also proposed which are analogous to the so-called modular structures. The validity of the model has been confirmed by refinements for phases with m = 6 and m = 9 in the homologous series. A few complex phenomena in real structures are taken into account by modifying the ideal model. [source] | ||||||||||||||||