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Modularity
Selected AbstractsMODULARITY OF THE ANGIOSPERM FEMALE GAMETOPHYTE AND ITS BEARING ON THE EARLY EVOLUTION OF ENDOSPERM IN FLOWERING PLANTSEVOLUTION, Issue 2 2003William E. Friedman Abstract The monosporic seven-celled/eight-nucleate Polygonumtype female gametophyte has long served as a focal point for discussion of the origin and subsequent evolution of the angiosperm female gametophyte. In Polygonumtype female gametophytes, two haploid female nuclei are incorporated into the central cell, and fusion of a sperm cell with the binucleate central cell produces a triploid endosperm with a complement of two maternal and one paternal genomes, characteristic of most angiosperms. We document the development of a four-celled/four-nucleate female gametophyte in Nuphar polysepala (Engelm.) and infer its presence in many other ancient lineages of angiosperms. The central cell of the female gametophyte in these taxa contains only one haploid nucleus; thus endosperm is diploid and has a ratio of one maternal to one paternal genome. Based on comparisons among flowering plants, we conclude that the angiosperm female gametophyte is constructed of modular developmental subunits. Each module is characterized by a common developmental pattern: (1) positioning of a single nucleus within a cytoplasmic domain (pole) of the female gametophyte; (2) two free-nuclear mitoses to yield four nuclei within that domain; and (3) partitioning of three uninucleate cells adjacent to the pole such that the fourth nucleus is confined to the central region of the female gametophyte (central cell). Within the basal angiosperm lineages Nymphaeales and Illiciales, female gametophytes are characterized by a single developmental module that produces a four-celled/four-nucleate structure with a haploid uninucleate central cell. A second pattern, typical of Amborella and the overwhelming majority of eumagnoliids, monocots, and eudicots, involves the early establishment of two developmental modules that produce a seven-celled/eight-nucleate female gametophyte with two haploid nuclei in the central cell. Comparative analysis of onto-genetic sequences suggests that the seven-celled female gametophyte (two modules) evolved by duplication and ectopic expression of an ancestral Nuphar- like developmental module within the chalazal domain of the female gametophyte. These analyses indicate that the first angiosperm female gametophytes were composed of a single developmental module, which upon double fertilization yielded a diploid endosperm. Early in angiosperm history this basic module was duplicated, and resulted in a seven-celled/eight-nucleate female gametophyte, which yielded a triploid endosperm with the characteristic 2:1 maternal to paternal genome ratio. [source] Modularity of the rodent mandible: Integrating bones, muscles, and teethEVOLUTION AND DEVELOPMENT, Issue 6 2008Miriam Leah Zelditch Summary Several models explain how a complex integrated system like the rodent mandible can arise from multiple developmental modules. The models propose various integrating mechanisms, including epigenetic effects of muscles on bones. We test five for their ability to predict correlations found in the individual (symmetric) and fluctuating asymmetric (FA) components of shape variation. We also use exploratory methods to discern patterns unanticipated by any model. Two models fit observed correlation matrices from both components: (1) parts originating in same mesenchymal condensation are integrated, (2) parts developmentally dependent on the same muscle form an integrated complex as do those dependent on teeth. Another fits the correlations observed in FA: each muscle insertion site is an integrated unit. However, no model fits well, and none predicts the complex structure found in the exploratory analyses, best described as a reticulated network. Furthermore, no model predicts the correlation between proximal parts of the condyloid and coronoid, which can exceed the correlations between proximal and distal parts of the same process. Additionally, no model predicts the correlation between molar alveolus and ramus and/or angular process, one of the highest correlations found in the FA component. That correlation contradicts the basic premise of all five developmental models, yet it should be anticipated from the epigenetic effects of mastication, possibly the primary morphogenetic process integrating the jaw coupling forces generated by muscle contraction with those experienced at teeth. [source] Cranial modularity and sequence heterochrony in mammalsEVOLUTION AND DEVELOPMENT, Issue 3 2007Anjali Goswami SUMMARY Heterochrony, the temporal shifting of developmental events relative to each other, requires a degree of autonomy among those processes or structures. Modularity, the division of larger structures or processes into autonomous sets of internally integrated units, is often discussed in relation to the concept of heterochrony. However, the relationship between the developmental modules derived from studies of heterochrony and evolutionary modules, which should be of adaptive importance and relate to the genotype,phenotype map, has not been explicitly studied. I analyzed a series of sectioned and whole cleared-and-stained embryological and neonatal specimens, supplemented with published ontogenetic data, to test the hypothesis that bones within the same phenotypic modules, as determined by morphometric analysis, are developmentally integrated and will display coordinated heterochronic shifts across taxa. Modularity was analyzed in cranial bone ossification sequences of 12 therian mammals. A dataset of 12,18 developmental events was used to assess if modularity in developmental sequences corresponds to six phenotypic modules, derived from a recent morphometric analysis of cranial modularity in mammals. Kendall's , was used to measure rank correlations, with randomization tests for significance. If modularity in developmental sequences corresponds to observed phenotypic modules, bones within a single phenotypic module should show integration of developmental timing, maintaining the same timing of ossification relative to each other, despite differences in overall ossification sequences across taxa. Analyses did not find any significant conservation of developmental timing within the six phenotypic modules, meaning that bones that are highly integrated in adult morphology are not significantly integrated in developmental timing. [source] Modularity, evolvability, and adaptive radiations: a comparison of the hemi- and holometabolous insectsEVOLUTION AND DEVELOPMENT, Issue 2 2001Andrew S. Yang SUMMARY Despite recent attention given to the concept of modularity and its potential contribution to the evolvability of organisms, there has been little mention of how such a contribution may affect rates of diversification or how this would be assessed. A first key prediction is that lineages with relatively greater degrees of modularity in given traits should exhibit higher rates of diversification. Four general conditions for testing this prediction of the modular evolvability hypothesis are outlined here. The potential role of modularity as a deterministic factor in adaptive radiations is best examined by looking at historic patterns of diversification rather than just levels of extant diversity, the focus of most analyses of key innovations. Recent developmental evidence supports the notion that phenotypes of juvenile and adult stages of insects with "complete" metamorphosis (Holometabola) are distinct developmental and evolvable modules compared to the highly correlated life stages of insects with "incomplete" metamorphosis (Hemimetabola). Family-level rates of diversification for these two groups were calculated from the fossil record. The Holometabola was found to have a significantly and characteristically higher rate of diversification compared to the less modular Hemimetabola, consistent with the idea that intrinsic differences in modularity can influence the long-term evolvability of organisms. The modular evolvability hypothesis also makes a second key prediction: that characters in more modular clades will exhibit greater levels of variation due to their independence. This provides an independent, phenotypically based test of the hypothesis. We discuss here how this second prediction may be tested in the case of the Hemi- and Holometabola. [source] The Concept of Modularity in Management Studies: A Literature ReviewINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 3 2010Diego Campagnolo During the last decade, modularity has attracted the attention of numerous management scholars, and both theoretical and empirical studies on this topic have flourished. However, this broad-based appeal has generated some controversies and ambiguities on how modularity should be defined, measured and used in managerially meaningful ways. This paper reviews the concept of modularity as a design principle of complex systems in management studies. Applying this criterion, 125 studies were selected and classified, grouped according to their prevalent unit of analysis: products, production systems and organizations. Although all these studies are based on Simon's seminal work on the hierarchical and nearly decomposable nature of complex systems (Simon, H.A. (1962). The architecture of complexity. Proceedings of the American Philosophical Society, 106, 467,482), this paper shows that they offer different definitions, measures and applications of the modularity concept. This review reveals the implicit structure of meanings underlying this literature and emphasizes that ambiguity in definitions and measures impedes rigorous empirical studies capable of understanding the relationship between modularity in product, in production and in organization design. Cautions and directions for future research are discussed. [source] Pragmatics, Modularity and Mind-readingMIND & LANGUAGE, Issue 1-2 2002Dan Sperber The central problem for pragmatics is that sentence meaning vastly underdetermines speaker's meaning. The goal of pragmatics is to explain how the gap between sentence meaning and speaker's meaning is bridged. This paper defends the broadly Gricean view that pragmatic interpretation is ultimately an exercise in mind-reading, involving the inferential attribution of intentions. We argue, however, that the interpretation process does not simply consist in applying general mind-reading abilities to a particular (communicative) domain. Rather, it involves a dedicated comprehension module, with its own special principles and mechanisms. We show how such a metacommunicative module might have evolved, and what principles and mechanisms it might contain. [source] Interfirm Modularity and Its Implications for Product Development,THE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 4 2005Nancy Staudenmayer Industries characterized by interfirm modularity, in which the component products of different firms work together to create a system, are becoming increasingly widespread. In such industries, the existence of a common architecture enables consumers to mix and match the products of different firms. Industries ranging from stereos, cameras, and bicycles to computers, printing, and wireless services are now characterized by interfirm modularity. While the increasing presence of this context has been documented, the implications for the product development process remain underdeveloped. For the present study, in-depth field-based case studies of seven firms experiencing an environment of interfirm modularity were conducted in order to deepen understanding of this important phenomenon. What unique challenges did this context pose and why? What solutions did firms experiment with, and which seemed to work? Based on an inductive process of data analysis from these case studies, three primary categories of challenges raised by this environment were identified. First, firms were frustrated at their lack of control over the definition of their own products. The set of features and functions in products were constrained to a great extent by an architecture that the firm did not control. Second, while an environment of interfirm modularity should in theory eliminate interdependencies among firms since interfaces between products are defined ex-ante, the present study found, ironically, that interdependencies were ubiquitous. Interdependencies continually emerged throughout the product development process, despite efforts to limit them. Third, firms found that the quantity and variegated nature of external relationships made their management exceedingly difficult. The sheer complexity was daunting, given both the size of the external network as well as the number of ties per external collaborator. Partners with whom control over the architecture was shared often had divergent interests,or at least not fully convergent interests. The solutions to these challenges were creative and in many cases counter to established wisdom. For instance, research has suggested many ways for a firm to influence architectural standards. While the firms in the present sample followed some of this advice, they also focused on a more neglected aspect of architecture,the compliance and testing standards that accompany modules and interfaces. By concentrating their efforts in a different area, even smaller firms in this sample were able to have some influence. Instead of focusing on the elimination of interdependencies, it was found that firms benefited from concentrating on the management of interdependencies as they emerged. Finally, while layers of management and "bureaucracy" are often viewed as unproductive, these firms found that adding structure, through positions such as Relationship Manager, was highly beneficial in handling the coordination and control of a wide range of external relationships. [source] How to think about the Modularity of Mind-ReadingTHE PHILOSOPHICAL QUARTERLY, Issue 199 2000Gregory Currie It has been suggested that the fixation of beliefs about people's beliefs, desires and intentions is modularized. We argue that this is unlikely. We argue that there is modularity lower down: social-intentional ,markers' are produced by an encapsulated mechanism intermediate between perception and belief-fixation, and that these markers make a distinctive contribution to the fixation of beliefs about the mental. But belief fixation itself is not modular. Finally, we suggest some complications to our simple picture, and some ways in which our thesis might shed light on pathologies of social understanding. [source] Book review: Modularity in Development and EvolutionBIOESSAYS, Issue 6 2005Nicolas Omont No abstract is available for this article. [source] Generate and Repair Machine TranslationCOMPUTATIONAL INTELLIGENCE, Issue 3 2002Kanlaya Naruedomkul We propose Generate and Repair Machine Translation (GRMT), a constraint,based approach to machine translation that focuses on accurate translation output. GRMT performs the translation by generating a Translation Candidate (TC), verifying the syntax and semantics of the TC and repairing the TC when required. GRMT comprises three modules: Analysis Lite Machine Translation (ALMT), Translation Candidate Evaluation (TCE) and Repair and Iterate (RI). The key features of GRMT are simplicity, modularity, extendibility, and multilinguality. An English,Thai translation system has been implemented to illustrate the performance of GRMT. The system has been developed and run under SWI,Prolog 3.2.8. The English and Thai grammars have been developed based on Head,Driven Phrase Structure Grammar (HPSG) and implemented on the Attribute Logic Engine (ALE). GRMT was tested to generate the translations for a number of sentences/phrases. Examples are provided throughout the article to illustrate how GRMT performs the translation process. [source] A comparative study of Java and C performance in two large-scale parallel applicationsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 15 2009Aamir Shafi Abstract In the 1990s the Message Passing Interface Forum defined MPI bindings for Fortran, C, and C++. With the success of MPI these relatively conservative languages have continued to dominate in the parallel computing community. There are compelling arguments in favour of more modern languages like Java. These include portability, better runtime error checking, modularity, and multi-threading. But these arguments have not converted many HPC programmers, perhaps due to the scarcity of full-scale scientific Java codes, and the lack of evidence for performance competitive with C or Fortran. This paper tries to redress this situation by porting two scientific applications to Java. Both of these applications are parallelized using our thread-safe Java messaging system,MPJ Express. The first application is the Gadget-2 code, which is a massively parallel structure formation code for cosmological simulations. The second application uses the finite-domain time-difference method for simulations in the area of computational electromagnetics. We evaluate and compare the performance of the Java and C versions of these two scientific applications, and demonstrate that the Java codes can achieve performance comparable with legacy applications written in conventional HPC languages. Copyright © 2009 John Wiley & Sons, Ltd. [source] An Exploratory Analysis of the Value of the Skills of IT Personnel: Their Relationship to IS Infrastructure and Competitive AdvantageDECISION SCIENCES, Issue 1 2001Terry Anthony Byrd Abstract Determining and assessing the requisite skills of information technology (IT) personnel have become critical as the value of IT has risen in modern organizations. In addition to technical skills traditionally expected of IT personnel, softer skills like managerial, business, and interpersonal skills have been increasingly cited in previous studies as mandatory for these employees. This paper uses a typology of IT personnel skills,technology management skills, business functional skills, interpersonal skills, and technical skills,and investigates their relationships to two information systems (IS) success variables, IS infrastructure flexibility and the competitive advantage provided by IS. The study investigates these relationships using the perceptions of chief information officers (CIOs) from mostly Fortune 2000 companies. The contributions of this study are: IT personnel skills do affect IS success, technical skills are viewed as the most important skill set in affecting IS infrastructure flexibility and competitive advantage, and modularity is viewed as more valuable to competitive advantage than integration. Several explanations are offered for the lack of positive relationships between the softer IT personnel skills and the dimensions of IS success used in this study. [source] Peer Commentaries on Marcy A. Kingsbury and Barbara L. Finlay's The cortex in multidimensional space: where do cortical areas come from?DEVELOPMENTAL SCIENCE, Issue 2 2001Article first published online: 28 JUN 200 Elizabeth Bates, Brain evolution and development: passing through the eye of the needle, p. 143 Serena M. Dudek, Multidimensional gene expression in cortical space, p. 145 Henry Kennedy and Colette Dehay, Gradients and boundaries: limits of modularity and its influence on the isocortex, p. 147 Sarah L. Pallas, Specification of mammalian neocortex: the power of the evo,devo approach in resolving the nature,nurture dichotomy, p. 148 Michel Roger, Embryonic stage of commitment of neocortical cells to develop area-specific connections, p. 151 M.W. Spratling and M.H. Johnson, Activity-dependent processes in regional cortical specialization, p. 153 [source] THE EVOLVABILITY OF GROWTH FORM IN A CLONAL SEAWEEDEVOLUTION, Issue 12 2009Keyne Monro Although modular construction is considered the key to adaptive growth or growth-form plasticity in sessile taxa (e.g., plants, seaweeds and colonial invertebrates), the serial expression of genes in morphogenesis may compromise its evolutionary potential if growth forms emerge as integrated wholes from module iteration. To explore the evolvability of growth form in the red seaweed, Asparagopsis armata, we estimated genetic variances, covariances, and cross-environment correlations for principal components of growth-form variation in contrasting light environments. We compared variance,covariance matrices across environments to test environmental effects on heritable variation and examined the potential for evolutionary change in the direction of plastic responses to light. Our results suggest that growth form in Asparagopsis may constitute only a single genetic entity whose plasticity affords only limited evolutionary potential. We argue that morphological integration arising from modular construction may constrain the evolvability of growth form in Asparagopsis, emphasizing the critical distinction between genetic and morphological modularity in this and other modular taxa. [source] MICRO- AND MACROEVOLUTIONARY DECOUPLING OF CICHLID JAWS: A TEST OF LIEM'S KEY INNOVATION HYPOTHESISEVOLUTION, Issue 10 2006C. D. Hulsey Abstract The extent to which elements of functional systems can change independently (modularity) likely influences the diversification of lineages. Major innovations in organismal design, like the pharyngeal jaw in cichlid fishes, may be key to a group's success when they relax constraints on diversification by increasing phenotypic modularity. In cichlid fishes, pharyngeal jaw modifications that enhanced the ability to breakdown prey may have freed their oral jaws from serving their ancestral dual role as a site of both prey capture and prey processing. This functional decoupling that allowed the oral jaws to become devoted solely to prey capture has been hypothesized to have permitted the two sets of cichlid jaws to evolve independently. We tested the hypothesis that oral and pharyngeal jaw mechanics are evolutionarily decoupled both within and among Neotropical Heroine cichlids. In the trophically polymorphic species Herichthys minckleyi, molariforms that exhibit enlarged molarlike pharyngeal jaw teeth were found to have approximately 400% greater lower jaw mass compared to H. minckleyi with the alternative papilliform pharyngeal morphology. However, oral jaw gape, lower jaw velocity ratios, anterior jaw linkage mechanics, and jaw protrusion did not differ between the morphotypes. In 40 other Heroine species, there was a weak correlation between oral jaw mechanics and pharyngeal jaw mass when phylogenetic history was ignored. Yet, after expansion of the cytochrome b phylogeny for Heroines, change in oral jaw mechanics was found to be independent of evolutionary change in pharyngeal jaw mass based on independent contrasts. Evolutionary decoupling of oral and pharyngeal jaw mechanics has likely played a critical role in the unparalleled trophic diversification of cichlid fishes. [source] ON THE ORIGIN OF MODULAR VARIATIONEVOLUTION, Issue 8 2002Hod Lipson Abstract We study the dynamics of modularization in a minimal substrate. A module is a functional unit relatively separable from its surrounding structure. Although it is known that modularity is useful both for robustness and for evolvability (Wagner 1996), there is no quantitative model describing how such modularity might originally emerge. Here we suggest, using simple computer simulations, that modularity arises spontaneously in evolutionary systems in response to variation, and that the amount of modular separation is logarithmically proportional to the rate of variation. Consequently, we predict that modular architectures would appear in correlation with high environmental change rates. Because this quantitative model does not require any special substrate to occur, it may also shed light on the origin of modular variation in nature. This observed relationship also indicates that modular design is a generic phenomenon that might be applicable to other fields, such as engineering: Engineering design methods based on evolutionary simulation would benefit from evolving to variable, rather than stationary, fitness criteria, as a weak and problem-independent method for inducing modularity. [source] Cranial modularity and sequence heterochrony in mammalsEVOLUTION AND DEVELOPMENT, Issue 3 2007Anjali Goswami SUMMARY Heterochrony, the temporal shifting of developmental events relative to each other, requires a degree of autonomy among those processes or structures. Modularity, the division of larger structures or processes into autonomous sets of internally integrated units, is often discussed in relation to the concept of heterochrony. However, the relationship between the developmental modules derived from studies of heterochrony and evolutionary modules, which should be of adaptive importance and relate to the genotype,phenotype map, has not been explicitly studied. I analyzed a series of sectioned and whole cleared-and-stained embryological and neonatal specimens, supplemented with published ontogenetic data, to test the hypothesis that bones within the same phenotypic modules, as determined by morphometric analysis, are developmentally integrated and will display coordinated heterochronic shifts across taxa. Modularity was analyzed in cranial bone ossification sequences of 12 therian mammals. A dataset of 12,18 developmental events was used to assess if modularity in developmental sequences corresponds to six phenotypic modules, derived from a recent morphometric analysis of cranial modularity in mammals. Kendall's , was used to measure rank correlations, with randomization tests for significance. If modularity in developmental sequences corresponds to observed phenotypic modules, bones within a single phenotypic module should show integration of developmental timing, maintaining the same timing of ossification relative to each other, despite differences in overall ossification sequences across taxa. Analyses did not find any significant conservation of developmental timing within the six phenotypic modules, meaning that bones that are highly integrated in adult morphology are not significantly integrated in developmental timing. [source] Modularity, evolvability, and adaptive radiations: a comparison of the hemi- and holometabolous insectsEVOLUTION AND DEVELOPMENT, Issue 2 2001Andrew S. Yang SUMMARY Despite recent attention given to the concept of modularity and its potential contribution to the evolvability of organisms, there has been little mention of how such a contribution may affect rates of diversification or how this would be assessed. A first key prediction is that lineages with relatively greater degrees of modularity in given traits should exhibit higher rates of diversification. Four general conditions for testing this prediction of the modular evolvability hypothesis are outlined here. The potential role of modularity as a deterministic factor in adaptive radiations is best examined by looking at historic patterns of diversification rather than just levels of extant diversity, the focus of most analyses of key innovations. Recent developmental evidence supports the notion that phenotypes of juvenile and adult stages of insects with "complete" metamorphosis (Holometabola) are distinct developmental and evolvable modules compared to the highly correlated life stages of insects with "incomplete" metamorphosis (Hemimetabola). Family-level rates of diversification for these two groups were calculated from the fossil record. The Holometabola was found to have a significantly and characteristically higher rate of diversification compared to the less modular Hemimetabola, consistent with the idea that intrinsic differences in modularity can influence the long-term evolvability of organisms. The modular evolvability hypothesis also makes a second key prediction: that characters in more modular clades will exhibit greater levels of variation due to their independence. This provides an independent, phenotypically based test of the hypothesis. We discuss here how this second prediction may be tested in the case of the Hemi- and Holometabola. [source] The Origins, Forms and Effects of Modularisation and Semesterisation in Ten UK-Based Business SchoolsHIGHER EDUCATION QUARTERLY, Issue 3 2000Huw Morris This paper examines the introduction of modularisation and semesterisation at ten UK-based business schools. Using this case study evidence, it is argued that the main reasons for the introduction of these schemes were the personal ambitions of senior managers, pressure from external regulatory agencies and a desire to emulate initiatives undertaken by competitor institutions. In addition, it is suggested that the form of these schemes varied between institutions as a consequence of the negotiations which accompanied the introduction of these new arrangements, and constraints imposed by the legacy of earlier degree structures, regulations from external agencies, institutional geography, limits on financial resources and the organization of internal management systems. The paper concludes by arguing that these constraints have meant that modularity has had limited effects on the experiences of staff and students, but that semesterisation has significantly increased costs without any accompanying benefits. [source] Modular stability tools for distributed computation and controlINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2003Jean-Jacques E. Slotine Abstract Much recent functional modelling of the central nervous system, beyond traditional ,neural net' approaches, focuses on its distributed computational architecture. This paper discusses extensions of our recent work aimed at understanding this architecture from an overall non-linear stability and convergence point of view, and at constructing artificial devices exploiting similar modularity. Applications to synchronization and to schooling are also described. The development makes extensive use of non-linear contraction theory. Copyright © 2003 John Wiley & Sons, Ltd. [source] Calm seas or troubled waters?INTERNATIONAL JOURNAL OF APPLIED LINGUISTICS, Issue 3 2005Transitions, definitions, disagreements in applied linguistics This article advances the position that an apparent current consensus over the nature and scope of applied linguistics is illusory. It is achieved only when definitions of the discipline are couched in the most general terms. When the details of theories are specified, we find fundamental differences of opinion both within applied linguistics and with linguistics. In the first part, the article reflects upon the history of applied linguistics, characterising it as falling into three periods. The second part presents a view of radical ideas in the third of these periods, focusing upon recent applied linguistic work in three areas: describing languages and defining speakers; modularity, modality and relativity; science, authority and action. Some work in these areas challenges fundamental linguistic as well as more conservative applied linguistic orthodoxies such as: the comparability of languages, the centrality of the native speaker, linguistic modularity and universalism, description without prescription, and the unique authority of science. [source] The Concept of Modularity in Management Studies: A Literature ReviewINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 3 2010Diego Campagnolo During the last decade, modularity has attracted the attention of numerous management scholars, and both theoretical and empirical studies on this topic have flourished. However, this broad-based appeal has generated some controversies and ambiguities on how modularity should be defined, measured and used in managerially meaningful ways. This paper reviews the concept of modularity as a design principle of complex systems in management studies. Applying this criterion, 125 studies were selected and classified, grouped according to their prevalent unit of analysis: products, production systems and organizations. Although all these studies are based on Simon's seminal work on the hierarchical and nearly decomposable nature of complex systems (Simon, H.A. (1962). The architecture of complexity. Proceedings of the American Philosophical Society, 106, 467,482), this paper shows that they offer different definitions, measures and applications of the modularity concept. This review reveals the implicit structure of meanings underlying this literature and emphasizes that ambiguity in definitions and measures impedes rigorous empirical studies capable of understanding the relationship between modularity in product, in production and in organization design. Cautions and directions for future research are discussed. [source] The effects of muscular dystrophy on the craniofacial shape of Mus musculusJOURNAL OF ANATOMY, Issue 6 2007Donna Carlson Jones Abstract Skeletal anomalies are common in patients with muscular dystrophy, despite an absence of mutations to genes that specifically direct skeletogenesis. In order to understand these anomalies further, we examined two strains of muscular dystrophy (laminin- and merosin-deficient) relative to controls, to determine how the weakened muscle forces affected skull shape in a mouse model. Shape was characterized with geometric morphometric techniques, improving upon the limited analytical power of the standard linear measurements. Through these techniques, we document the specific types of cranial skeletal deformation produced by the two strains, each with individual shape abnormalities. The mice with merosin deficiency (with an earlier age of onset) developed skulls with more deformation, probably related to the earlier ontogenetic timing of disease onset. Future examinations of these mouse models may provide insight regarding the impact of muscular forces and the production and maintenance of craniofacial integration and modularity. [source] Realizing the Potential of Real Options: Does Theory Meet Practice?JOURNAL OF APPLIED CORPORATE FINANCE, Issue 2 2005Alexander Triantis The idea of viewing corporate investment opportunities as "real options" has been around for over 25 years. Real options concepts and techniques now routinely appear in academic research in finance and economics, and have begun to influence scholarly work in virtually every business discipline, including strategy, organizations, management science, operations management, information systems, accounting, and marketing. Real options concepts have also made considerable headway in practice. Corporate managers are more likely to recognize options in their strategic planning process, and have become more proactive in designing flexibility into projects and contracts, frequently using real options vocabulary in their discussions. Thanks in part to the spread of real options thinking, today's strategic planners are more likely than their predecessors to recognize the "option" value of actions like the following: , dividing up large projects into a number of stages; , investing in the acquisition or production of information; , introducing "modularity" in manufacturing and design; , developing competing prototypes for new products; and , investing in overseas markets. But if real options has clearly succeeded as a way of thinking, the application of real options valuation methods has been limited to companies in relatively few industries and has thus failed to live up to expectations created in the mid- to late-1990s. Increased corporate acceptance and implementations of real options valuation techniques will require several changes coming together. On the theory side, we need more realistic models that better reflect differences between financial and real options, simple heuristic methods that can be more easily implemented (but that have been carefully benchmarked against more precise models), and better guidance on implementation issues such as the estimation of discount rates for the "optionless" underlying projects. On the practitioner side, we need user-friendly real options software, more senior-level buy-in, more deliberate diffusion of real options knowledge throughout organizations, better alignment of managerial incentives with long-term shareholder value, and better-designed contracts to correct the misalignment of incentives across the value chain. If these challenges can be met, there will continue to be a steady if gradual diffusion of real options analysis throughout organizations over the next few decades, with real options eventually becoming not only a standard part of corporate strategic planning, but also the primary valuation tool for assessing the expected shareholder effect of large capital investment projects. [source] The effect of surface treatments on the fretting behavior of Ti-6Al-4V alloyJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008Matteo Dalmiglio Abstract Stem modularity in total hip replacement introduces an additional taper joint between Ti-6Al-4V stem components with the potential for fretting corrosion processes. One possible way to reduce the susceptibility of the Ti-6Al-4V/Ti-6Al-4V interface to fretting is the surface modification of the Ti-6Al-4V alloy. Among the tested, industrially available surface treatments, a combination of two deep anodic spark deposition treatments followed by barrel polishing resulted in a four times lower material release with respect to untreated, machined fretting pad surfaces. The fretting release has been quantified by means of radiotracers introduced in the alloy surface by proton irradiation. In a simple sphere on flat geometry, the semispherical fretting pads were pressed against flat, dog-bone shaped Ti-6Al-4V fatigue samples cyclically loaded at 4 Hz. In this way a cyclic displacement amplitude along the surfaces of 20 ,m has been achieved. A further simplification consisted in the use of deionized water as lubricant. A comparison of the radiotracer results with an electrochemical material characterization after selected treatments by potentiostatic tests of modular stems in 0.9% NaCl at 40°C for 10 days confirmed the benefit of deep anodic spark deposition and subsequent barrel polishing for improving the fretting behavior of Ti-6Al-4V. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Scheduling dispensing and counting in secondary pharmaceutical manufacturingAICHE JOURNAL, Issue 5 2009Michele Ciavotta Abstract In this article, we describe a general methodology for operations scheduling in dispensing and counting departments of pharmaceutical manufacturing plants. The departments are modeled as a multiobjective parallel machines scheduling problem under a number of both standard and realistic constraints, such as release times, due dates and deadlines, particular sequence-dependent setup times, machine unavailabilities, and maximum campaign size. Main characteristics of the methodology are the modularity of the solution algorithms, the adaptability to different objectives and constraints to fulfill production requirements, the easiness of implementation, and the ability of incorporating human experience in the scheduling algorithms. Computational experience carried out on two case studies from a real pharmaceutical plant shows the effectiveness of this approach. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The Drink You Have When You're Not Having a DrinkMIND & LANGUAGE, Issue 3 2008ROBERT A. WILSON In this brief commentary I focus on these foundations,Carruthers' conception of modularity, his arguments for thinking that the mind is massively modular in structure, and his view of human cognitive architecture. [source] Us, Them and It: Modules, Genes, Environments and EvolutionMIND & LANGUAGE, Issue 3 2008FIONA COWIE However, it suffers from two major theoretical flaws. First, Carruthers' concept of a module is weak, so much so that it robs his thesis of massive modularity of any real substance. Second, his conception of how the mind's modules evolved ignores the role of niche construction and cultural evolution to its detriment. [source] Differences in pollinator faunas may generate geographic differences in floral morphology and integration in Narcissus papyraceus (Amaryllidaceae)OIKOS, Issue 11 2007Rocío Pérez-Barrales Pollinators may generate selective pressures that affect covariation patterns of multiple traits as well as the mean values of single floral morphological traits. Berg predicted that flowers pollinated by animals whose morphology closely matches the flower's shape will be phenotypically more integrated (tighter correlation of flower traits) than will flowers pollinated by animals not closely fitting the floral morphology. We tested this hypothesis by comparing, in the Strait of Gibraltar region (south Spain, northern Morocco), populations of Narcissus papyraceus that have geographical differences in pollinator faunas. Long-tongued, nectar-feeding moths dominate the pollinator faunas of those populations close to the Strait of Gibraltar, whereas short-tongued, pollen-feeding syrphid flies dominate in peripheral populations farther from the Strait. Populations pollinated by moths and flies differed in the mean values of several floral traits, consistent with the evolution of regional pollination ecotypes. Populations pollinated by moths showed stronger intercorrelation (floral integration) than populations pollinated by hoverflies. Moth-pollinated populations also showed less variation in flower traits than vegetative traits, and this difference was stronger than in fly-pollinated populations. Thus, the pattern of differences in the phenotypic architecture of the Narcissus flowers is consistent with the hypothesis that populations have responded to different selective pressures generated by different pollinators. These data also supported most of the specific predictions of Berg's hypotheses about integration and modularity. [source] Time,accurate Modular CFD-CSD Coupling for Aeroelastic Rotor SimulationsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003A. Altmikus Dipl.-Ing. This paper addresses the timewise accuracy of different coupling approaches applied to instationary aeroelastic simulations of rotors in forward flight. Two different approaches which are widely discussed in literature are examined: the tight or strong coupling, and the fully integrated or monolithic coupling. Strong coupling means an exchange of fluid loads and structural deformations at each time step which is effectuated in a fully modular manner. We will address aspects of conservativity and time-accuracy, and will present results for a helicopter forward flight scenario. However, objections concerning the correct solution of the global non-linear three field problem , structure, grid deformation, aerodynamics , remain. These objections are normally rejected by the monolithic approach. Here, a common set of partial differential equations is derived and solved in a single code. However, a truly monolithic system of equations is only needed for stability analysis, and it can be decomposed in a three field problem respecting appropriate boundary conditions for each domain. Thus, modularity can be maintained, conceiving a quasi-monolithic procedure, when both domains are simultaneously solved in a common non-linear iteration loop on a per time-step basis. First results will be shown for a 2D flutter testcase. [source] | |||||||||||||||||||||||||||||||