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Line System (line + system)
Kinds of Line System Selected AbstractsModeling and Managing the Percentage of Satisfied Customers in Hidden and Revealed Waiting Line SystemsPRODUCTION AND OPERATIONS MANAGEMENT, Issue 1 2006Chester Chambers We perform an analysis of various queueing systems with an emphasis on estimating a single performance metric. This metric is defined to be the percentage of customers whose actual waiting time was less than their individual waiting time threshold. We label this metric the Percentage of Satisfied Customers (PSC.) This threshold is a reflection of the customers' expectation of a reasonable waiting time in the system given its current state. Cases in which no system state information is available to the customer are referred to as "hidden queues." For such systems, the waiting time threshold is independent of the length of the waiting line, and it is randomly drawn from a distribution of threshold values for the customer population. The literature generally assumes that such thresholds are exponentially distributed. For these cases, we derive closed form expressions for our performance metric for a variety of possible service time distributions. We also relax this assumption for cases where service times are exponential and derive closed form results for a large class of threshold distributions. We analyze such queues for both single and multi-server systems. We refer to cases in which customers may observe the length of the line as "revealed" queues." We perform a parallel analysis for both single and multi-server revealed queues. The chief distinction is that for these cases, customers may develop threshold values that are dependent upon the number of customers in the system upon their arrival. The new perspective this paper brings to the modeling of the performance of waiting line systems allows us to rethink and suggest ways to enhance the effectiveness of various managerial options for improving the service quality and customer satisfaction of waiting line systems. We conclude with many useful insights on ways to improve customer satisfaction in waiting line situations that follow directly from our analysis. [source] Cell proliferation in the developing lateral line system of zebrafish embryosDEVELOPMENTAL DYNAMICS, Issue 2 2005Laurent Laguerre Abstract The sensory organs of the embryonic lateral line system are deposited by migrating primordia that originate in the otic region. Here, we examine the pattern of cell proliferation in the posterior lateral line system. We conclude that three phases of cell proliferation are involved in the generation of this system, separated by two phases of mitotic quiescence. The first phase corresponds to generalized proliferation during gastrulation, followed by a first period of quiescence that may be related to the determination of the lateral line precursor cells. A second phase of proliferation takes place in the placode and migrating primordium. This region is organized in annuli that correspond to the expression of proneural/neurogenic genes. A second period of quiescence follows, corresponding to deposition and differentiation of the sensory organs. The third period of proliferation corresponds to continued renewal of hair cells by division of support cells within each sensory organ. Developmental Dynamics 233:466,472, 2005. © 2005 Wiley-Liss, Inc. [source] Postembryonic development of the cranial lateral line canals and neuromasts in zebrafishDEVELOPMENTAL DYNAMICS, Issue 3 2003Jacqueline F. Webb Abstract The development of the cranial lateral line canals and neuromast organs are described in postembryonic zebrafish (0,80 days postfertilization). Cranial canal development commences several weeks after hatch, is initiated in the vicinity of individual neuromasts, and occurs in four discrete stages that are described histologically. Neuromasts remain in open canal grooves for several weeks during which they dramatically change shape and increase in size by adding hair cells at a rate one-tenth that in the zebrafish inner ear. Scanning electron microscopy demonstrates that neuromasts elongate perpendicular to the canal axis and the axis of hair cell polarization and that they lack a prominent nonsensory cell population surrounding the hair cells,features that make zebrafish neuromasts unusual among fishes. These results demand a reassessment of neuromast and lateral line canal diversity among fishes and highlight the utility of the lateral line system of postembryonic zebrafish for experimental and genetic studies of the development and growth of hair cell epithelia. Developmental Dynamics, 2003. © 2003 Wiley-Liss, Inc. [source] Phylogenetic trends in the abundance and distribution of pit organs of elasmobranchsACTA ZOOLOGICA, Issue 4 2004M. B. Peach Abstract Pit organs (free neuromasts of the mechanosensory lateral line system) are distributed over the skin of elasmobranchs. To investigate phylogenetic trends in the distribution and abundance of pit organs, 12 relevant morphological characters were added to an existing matrix of morphological data (plus two additional end terminals), which was then re-analysed using cladistic parsimony methods (paup* 4.0b10). Character transformations were traced onto the most parsimonious phylogenetic trees. The results suggest the following interpretations. First, the distinctive overlapping denticles covering the pit organs in many sharks are a derived feature; plesiomorphic elasmobranchs have pit organs in open slits, with widely spaced accessory denticles. Second, the number of pit organs on the ventral surface of rays has been reduced during evolution, and third, spiracular pit organs have changed position or have been lost on several occasions in elasmobranch evolution. The concentrated-changes test in macclade (version 4.05) was used to investigate the association between a pelagic lifestyle and loss of spiracular pit organs (the only character transformation that occurred more than once within pelagic taxa). Depending on the choice of tree, the association was either nonsignificant at P = 0.06 or significant at P < 0.05. Future studies, using species within more restricted elasmobranch clades, are needed to resolve this issue. [source] Lateral line system of fishINTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 1 2009Horst BLECKMANN Abstract The lateral line is a sensory system that allows fishes to detect weak water motions and pressure gradients. The smallest functional unit of the lateral line is the neuromast, a sensory structure that consists of a hair cell epithelium and a cupula that connects the ciliary bundles of the hair cells with the water surrounding the fish. The lateral line of most fishes consists of hundreds of superficial neuromasts spread over the head, trunk and tail fin. In addition, many fish have neuromasts embedded in lateral line canals that open to the environment through a series of pores. The present paper reviews some more recent aspects of the morphology, behavioral relevance and physiology of the fish lateral line. In addition, it reports some new findings with regard to the coding of bulk water flow. [source] Multidimensional analysis of fishery production systems in the state of Pernambuco, BrazilJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2009R. P. Lessa Summary A total of 17 fishery systems covering gillnets, traps and seines targeting fish and crustaceans as well as hand-collected mussels in the state of Pernambuco (Brazil) were compared and analyzed in the present study using the RAPFISH method and 57 attributes to qualify five evaluation dimensions: economic, social, ecological, technological and management. The aim was to determine the sustainability of each field from the fishery (i.e. stocks) and social standpoint (i.e. fishermen). With regard to sustainability, it was generally apparent that the fisheries analyzed are far from any ideal that would permit long-term exploitation, but are nonetheless also distant from the extremes of non-sustainability in the environments investigated. The low degree of organization demonstrated in most fisheries of Pernambuco and the low level of schooling among the fishermen contribute toward maintaining the status quo, with an increase in situations of conflict and a lack of valorization regarding the activities. The shrimp system is the least sustainable, mainly due to its environmental impact; however, this is compensated by the relatively higher quality of living provided stakeholders through its exploitation. The evaluation dimensions showed the most sustainable system in Pernambuco to be the stationary ,uncovered pound net', followed by the line system. Alternative procedures for integrated fishery management, such as an increase in statistical data, coastal zoning to limit shrimp farms and establishing protected areas are proposed and discussed. Such procedures may contribute toward the formulation of public policies for the fishery industry of the state, which is essentially made up of artisanal fisheries with low yields and exercised by the 11 926 fishermen affiliated with coastal fishing colonies. [source] Development of the lateral line system in the sea bassJOURNAL OF FISH BIOLOGY, Issue 1 2003J. P. Diaz Using light and electron microscopy, a study of the development of the lateral line system of the sea bass Dicentrarchus labrax, from embryo to adult, revealed that the first free neuromasts appeared on the head shortly before hatching and multiplied during the larval stage. They were aligned on the head and trunk in a pattern which corresponded to the location of future canals. The transition to the juvenile stage marked the start of important anatomical changes during which head and trunk canals were formed successively. Neuromasts, with a cupula and consisting of standard sensory cells and supporting cells, were characterized by bidirectional polarity. The exact location of the first neuromast formed in the embryo was identified and its differentiation monitored from primordium to eruption. This neuromast was distinguishable from the others by its radial polarity. Correlations were made between the development of the lateral line system and the behaviour of the sea bass. [source] Lateral line system and its innervation in Tetraodontiformes with outgroup comparisons: Descriptions and phylogenetic implicationsJOURNAL OF MORPHOLOGY, Issue 5 2010Masanori Nakae Abstract The lateral line system and its innervation in ten tetraodontiform families and five outgroup taxa were examined. Although some homology issues remained unresolved, tetraodontiforms were characterized by having two types (at least) of superficial neuromasts (defined by the presence or absence of supporting structures) and accessory lateral lines and neuromasts (except Molidae in which "accessory" elements were absent). The preopercular line in Tetraodontiformes was not homologous with that of typical teleosts, because the line was innervated by the opercular ramule that was newly derived from the mandibular ramus, the condition being identical to that in Lophiidae. Within Tetraodontiformes, the number of neuromasts varied between 70 and 277 in the main lines and between 0 and 52 in accessory elements. Variations were also recognized in the presence or absence of the supraorbital commissure, mandibular line, otic line, postotic line, ventral trunk line, and some lateral line nerve rami, most notably the dorsal branch of the opercular ramule, being absent in Aracanidae, Ostraciidae, Tetraodontidae, Diodontidae, and Molidae. Morphological characteristics derived from the lateral line system and its innervation provided some support for a sister relationship of tetraodontiforms with lophiiforms. J. Morphol., 2010. © 2009 Wiley-Liss, Inc. [source] The comparative morphology of pit organs in elasmobranchsJOURNAL OF MORPHOLOGY, Issue 6 2009M.B. Peach Abstract The pit organs of elasmobranchs (sharks, skates and rays) are free neuromasts of the mechanosensory lateral line system. Pit organs, however, appear to have some structural differences from the free neuromasts of bony fishes and amphibians. In this study, the morphology of pit organs was investigated by scanning electron microscopy in six shark and three ray species. In each species, pit organs contained typical lateral line hair cells with apical stereovilli of different lengths arranged in an "organ-pipe" configuration. Supporting cells also bore numerous apical microvilli taller than those observed in other vertebrate lateral line organs. Pit organs were either covered by overlapping denticles, located in open grooves bordered by denticles, or in grooves without associated denticles. The possible functional implications of these morphological features, including modification of water flow and sensory filtering properties, are discussed. J. Morphol. 2009. © 2009 Wiley-Liss, Inc. [source] Morphology of the prometamorphic larva of the spadefoot toad, Scaphiopus intermontanus (Anura: Pelobatidae), with an emphasis on the lateral line system and mouthpartsJOURNAL OF MORPHOLOGY, Issue 2 2002John A. Hall Abstract We provide a detailed description of the larval morphology of the Great Basin spadefoot toad (Scaphiopus intermontanus), a species with documented morphological variability in larval structures associated with feeding. We based our findings on laboratory-raised individuals fed a herbivorous diet. We characterized the morphology of the prometamorphic larva (limited to developmental stages 37 and 38) and then related our findings to the larval ecology of the species. Based on its morphology, such as slightly depressed body, dorsally positioned eyes, anteroventrally oriented oral disc, intermediate tail fin height and slightly attenuated tail tip, relative lack of ventral neuromasts (compared to Xenopus laevis), and pigmentation banding patterns, and habits, such as selection of breeding sites by adults and larval foraging behavior, S. intermontanus can be characterized best as belonging to a (lentic-) benthic guild of anuran larvae. Nevertheless, the larvae are capable of occupying a broader array of ecological niches. Because we characterized individuals raised on a herbivorous diet, our morphological descriptions apply only to the herbivorous S. intermontanus larva (and perhaps to those larvae that are dietary generalists and may feed carnivorously only infrequently). Our findings can serve as a baseline for future morphological and developmental comparisons with the carnivorous morphological variant of this species. J. Morphol. 252:114,130, 2002. © 2002 Wiley-Liss, Inc. [source] Industrial tools for the feature location problem: an exploratory studyJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 6 2006Sharon Simmons Abstract Software engineers who maintain and enhance large systems often encounter the feature location problem: where in the many thousands of lines of code is a particular user feature implemented? Several methods of addressing the problem have been proposed, most of which involve tracing the execution of the system and analyzing the traces. Some supporting academic tools are available. However, companies that depend on the successful evolution of large systems are more likely to use new methods if they are supported by industrial-strength tools of known reliability. This article describes a study performed with Motorola, Inc. to see whether there were any pitfalls in using Metrowerks CodeTEST and Klocwork inSight for feature location on message-passing software similar to systems that Motorola maintains. These two tools were combined with TraceGraph, an academic trace comparison tool. The study identified two main problems. First, some ,glue' code and workarounds were needed to get CodeTEST to generate a trace for an interval of time in which the feature was operating. Second, getting information out of TraceGraph and into inSight was needlessly complicated for a user. However, with a moderate amount of work, the tool combination was effective in locating, understanding and documenting features. Study participants completed these steps in typically 3,4 hours per feature, studying only a few hundred lines out of a 200,000 line system. An ongoing project with Motorola is focused on improving tool integration with the hope of making feature location common practice at Motorola. Copyright © 2006 John Wiley & Sons, Ltd. [source] Information rate bounds in common-mode aided wireline communicationsEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2006Thomas Magesacher Communication over the copper twisted-pair channel is performed by transmitting and receiving differential-mode (DM) signals. In this paper, we extend the conventional DM receiver scheme by incorporating the common-mode (CM) signal, which is strongly correlated with the DM signal and can be extracted at the end of every wire pair. The wireline channel, including the CM receive signal, is modelled as a Gaussian vector (multiple-input multiple-output) channel with memory and an arbitrary number of disturbers that introduce interference which can be correlated both temporally and spatially. We investigate the potential of CM-aided reception in terms of information rate for single-user digital subscriber line systems (xDSL) operating on a single pair. Numerical results of information rate calculations using measured channel data are presented. The achievable information rate of the twisted-pair channel when incorporating the CM signal in practically relevant example scenarios can exceed the information rate of the conventional DM channel by a factor of up to two. Copyright © 2005 AEIT. [source] Mutational inactivation of TGFBR2 in microsatellite unstable colon cancer arises from the cooperation of genomic instability and the clonal outgrowth of transforming growth factor , resistant cellsGENES, CHROMOSOMES AND CANCER, Issue 2 2008Swati Biswas The mutational inactivation of transforming growth factor , receptor type II (TGFBR2) occurs in ,30% of colon cancers and promotes the formation of colon cancer by inhibiting the tumor suppressor activity of the TGFB signaling pathway. TGFBR2 mutations occur in >90% of microsatellite unstable (MSI) colon cancers and affect a polyadenine tract in exon 3 of TGFBR2, called BAT-RII, which is vulnerable to mutation in the setting of DNA mismatch repair (MMR) system deficiency. In light of the vulnerable nature of the BAT-RII tract in the setting of MMR inactivation and the favorable effects of TGFBR2 inactivation in colon cancer, analysis of TGFBR2 inactivation provides an opportunity to assess the roles of genomic instability vs. clonal selection in cells acquiring TGFBR2 BAT-RII tract mutations in MSI colon cancer formation. The contribution of genomic instability and/or clonal evolution to the mutational inactivation of TGBFR2 in MSI colon cancers has not been studied in a systematic way that would allow a determination of the relative contribution of these two mechanisms in the formation of MSI colon cancer. It has not been demonstrated whether the BAT-RII tract mutations are strictly a consequence of the BAT-RII region being hypermutable in the setting of MMR deficiency or if the mutations are rather a consequence of clonal selection pressure against the TGFB receptor. Through the use of defined cell line systems, we show that both genomic instability and clonal selection of TGFB resistant cells contribute to the high frequency of TGFBR2 mutations in MSI colon cancer. © 2007 Wiley-Liss, Inc. [source] Modeling and Managing the Percentage of Satisfied Customers in Hidden and Revealed Waiting Line SystemsPRODUCTION AND OPERATIONS MANAGEMENT, Issue 1 2006Chester Chambers We perform an analysis of various queueing systems with an emphasis on estimating a single performance metric. This metric is defined to be the percentage of customers whose actual waiting time was less than their individual waiting time threshold. We label this metric the Percentage of Satisfied Customers (PSC.) This threshold is a reflection of the customers' expectation of a reasonable waiting time in the system given its current state. Cases in which no system state information is available to the customer are referred to as "hidden queues." For such systems, the waiting time threshold is independent of the length of the waiting line, and it is randomly drawn from a distribution of threshold values for the customer population. The literature generally assumes that such thresholds are exponentially distributed. For these cases, we derive closed form expressions for our performance metric for a variety of possible service time distributions. We also relax this assumption for cases where service times are exponential and derive closed form results for a large class of threshold distributions. We analyze such queues for both single and multi-server systems. We refer to cases in which customers may observe the length of the line as "revealed" queues." We perform a parallel analysis for both single and multi-server revealed queues. The chief distinction is that for these cases, customers may develop threshold values that are dependent upon the number of customers in the system upon their arrival. The new perspective this paper brings to the modeling of the performance of waiting line systems allows us to rethink and suggest ways to enhance the effectiveness of various managerial options for improving the service quality and customer satisfaction of waiting line systems. We conclude with many useful insights on ways to improve customer satisfaction in waiting line situations that follow directly from our analysis. [source] Density currents in shear flows: Effects of rigid lid and cold-pool internal circulation, and application to squall line dynamicsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 579 2002Ming Xue Abstract Idealized density current models that contain a rigid lid, developed in previous studies, are evaluated. It is shown, through numerical experiments, that a realistic stable layer placed at the level of the rigid lid acts very much like a rigid lid, in confining the environmental flow to the levels below and in controlling the behaviour of density currents that propagate in the flow. When this stable layer is replaced by a neutrally stable layer, the behaviour of the density current is very different. These results support the hypothesis that in the atmosphere, the tropopause or a tropospheric inversion layer acts much like a rigid lid in the idealized density current models, and the solutions of these models are applicable to organized quasi-two-dimensional convective systems such as squall lines in the atmosphere. The effects of cold-pool internal circulations on density current behaviour are also examined. When a single circulation is present initially inside the cold pool, the direction of circulation that gives rise to a smaller shear across the density interface leads to a smoother interface and a much more steady density current head. Large-amplitude eddies develop along the interface when the direction of circulation is reversed. When two layers of shear are initially present inside the cold pool, the flow pattern inside the cold pool tends to be dominated by the circulation of the lower layer. In this case, the behaviour of the density interface and density current head depends on more than just the initial cross-interface shear. The overall flow pattern in the density current, in which the cold-pool circulation contains rearward flows at the ground level, bears a close similarity to that found in mature squall line systems, as shown by comparisons with a simulated squall line. When the cold pool in a squall line is defined in terms of the equivalent potential temperature, the solutions of idealized density currents in sheared flows become more readily applicable to squall lines. Copyright © 2002 Royal Meteorological Society. [source] | ||||||||||||||||