122,671 research outputs found

    The limits of mean-field heterozygosity estimates under spatial extension in simulated plant populations

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    Computational models of evolutionary processes are increasingly required to incorporate multiple and diverse sources of data. A popular feature to include in population genetics models is spatial extension, which reflects more accurately natural populations than does a mean field approach. However, such models necessarily violate the mean field assumptions of classical population genetics, as do natural populations in the real world. Recently, it has been questioned whether classical approaches are truly applicable to the real world. Individual based models (IBM) are a powerful and versatile approach to achieve integration in models. In this study an IBM was used to examine how populations of plants deviate from classical expectations under spatial extension. Populations of plants that used three different mating strategies were placed in a range of arena sizes giving crowded to sparse occupation densities. Using a measure of population density, the pollen communication distance (Pcd), the deviation exhibited by outbreeding populations differed from classical mean field expectations by less than 5% when Pcd was less than 1, and over this threshold value the deviation significantly increased. Populations with an intermediate mating strategy did not have such a threshold and deviated directly with increasing isolation between individuals. Populations with a selfing strategy were influenced more by the mating strategy than by increased isolation. In all cases pollen dispersal was more influential than seed dispersal. The IBM model showed that mean field calculations can be reasonably applied to natural outbreeding plant populations that occur at a density in which individuals are less than the average pollen dispersal distance from their neighbors

    Middleware’s message : the financial technics of codata

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    In this paper, I will argue for the relevance of certain distinctive features of messaging systems, namely those in which data (a) can be sent and received asynchronously, (b) can be sent to multiple simultaneous recipients and (c) is received as a “potentially infinite” flow of unpredictable events. I will describe the social technology of the stock ticker, a telegraphic device introduced at the New York Stock Exchange in the 1860s, with reference to early twentieth century philosophers of synchronous experience (Bergson), simultaneous sign interpretations (Mead and Peirce), and flows of discrete events (Bachelard). Then, I will show how the ticker’s data flows developed into the 1990s-era technologies of message queues and message brokers, which distinguished themselves through their asynchronous implementation of ticker-like message feeds sent between otherwise incompatible computers and terminals. These latter systems’ characteristic “publish/subscribe” communication pattern was one in which conceptually centralized (if logically distributed) flows of messages would be “published,” and for which “subscribers” would be spontaneously notified when events of interest occurred. This paradigm—common to the so-called “message-oriented middleware” systems of the late 1990s—would re-emerge in different asynchronous distributed system contexts over the following decades, from “push media” to Twitter to the Internet of Things

    Physiological responses of reared sea bream (Sparus aurata Linnaeus, 1758) to an Amyloodinium ocellatum outbreak

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    Amyloodiniosis represents a major bottleneck for semi-intensive aquaculture production in Southern Europe, causing extremely high mortalities. Amyloodinium ocellatum is a parasitic dinoflagellate that can infest almost all fish, crustacean and bivalves that live within its ecological range. Fish mortalities are usually attributed to anoxia, associated with serious gill hyperplasia, inflammation, haemorrhage and necrosis in heavy infestations; or with osmoregulatory impairment and secondary microbial infections due to severe epithelial damage in mild infestation. However, physiological information about the host responses to A.ocellatum infestation is scarce. In this work, we analysed the proteome of gilthead sea bream (Sparus aurata) plasma and relate it with haematological and immunological indicators, in order to enlighten the different physiological responses when exposed to an A.ocellatum outbreak. Using 2D-DIGE, immunological and haematological analysis and in response to the A.ocellatum contamination we have identified several proteins associated with acute-phase response, inflammation, lipid transport, homoeostasis, and osmoregulation, wound healing, neoplasia and iron transport. Overall, this preliminary study revealed that amyloodiniosis affects some fish functional pathways as revealed by the changes in the plasma proteome of S. aurata, and that the innate immunological system is not activated in the presence of the parasite.DIVERSIAQUA, Portugal [MAR2020]Fundacao para a Ciencia e Tecnologia [SFRH/BD/118601/2016]info:eu-repo/semantics/publishedVersio

    The Managed Service Paradox

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    This paper examines the contrasts in the provision of managed service in the information and communication technology (ICT) sector. It highlights the polarization between infrastructure services that are growing in scale and increasingly becoming a commoditized, and customized or even one-of-a-kind service projects. The paper refers to the approaches taken by three highly innovative advanced service companies, IBM, Ericsson, and Cable & Wireless, to package and deliver ICT service on a more industrialized basis. The authors identify the six-stage process that describes these companies’ journeys to date from. They explore the challenges these companies faced on that journey as well those currently facing them as they move to a higher degree of industrialization. To address these challenges, the authors propose a model with three axes: offering development, service delivery, and go to market. The model demonstrates how the increasing industrialization of managed service requires an approach integrating all three of these dimensions. They also show that strong governance is required to address the impacts of technological evolution, marketplace dynamics, and corporate culture. The paper has formed the basis of the academic and executive education programs taught at both Imperial College and is the heart of the new service design masters program at the Royal College of Art. Because of its relevance to large industrial companies seeking to transition from an industrial offering to a service or solution led offering, the paper has been turned into a course that has been delivered to Arup, Vodafone, Finmeccanica, Telefonica, Samsung and Laing O’Rourke to date and this programme has been delivered by the authors in Korea, Taiwan, US and the UK

    The Drosophila Inhibitor of Apoptosis (IAP) DIAP2 Is Dispensable for Cell Survival, Required for the Innate Immune Response to Gram-negative Bacterial Infection, and Can Be Negatively Regulated by the Reaper/Hid/Grim Family of IAP-binding Apoptosis Inducers

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    Many inhibitor of apoptosis (IAP) family proteins inhibit apoptosis. IAPs contain N-terminal baculovirus IAP repeat domains and a C-terminal RING ubiquitin ligase domain. Drosophila IAP DIAP1 is essential for the survival of many cells, protecting them from apoptosis by inhibiting active caspases. Apoptosis initiates when proteins such as Reaper, Hid, and Grim bind a surface groove in DIAP1 baculovirus IAP repeat domains via an N-terminal IAP-binding motif. This evolutionarily conserved interaction disrupts DIAP1-caspase interactions, unleashing apoptosis-inducing caspase activity. A second Drosophila IAP, DIAP2, also binds Rpr and Hid and inhibits apoptosis in multiple contexts when overexpressed. However, due to a lack of mutants, little is known about the normal functions of DIAP2. We report the generation of diap2 null mutants. These flies are viable and show no defects in developmental or stress-induced apoptosis. Instead, DIAP2 is required for the innate immune response to Gram-negative bacterial infection. DIAP2 promotes cytoplasmic cleavage and nuclear translocation of the NF-{kappa}B homolog Relish, and this requires the DIAP2 RING domain. Increasing the genetic dose of diap2 results in an increased immune response, whereas expression of Rpr or Hid results in down-regulation of DIAP2 protein levels. Together these observations suggest that DIAP2 can regulate immune signaling in a dose-dependent manner, and this can be regulated by IBM-containing proteins. Therefore, diap2 may identify a point of convergence between apoptosis and immune signaling pathways

    A mass-structured individual-based model of the chemostat: convergence and simulation

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    We propose a model of chemostat where the bacterial population is individually-based, each bacterium is explicitly represented and has a mass evolving continuously over time. The substrate concentration is represented as a conventional ordinary differential equation. These two components are coupled with the bacterial consumption. Mechanisms acting on the bacteria are explicitly described (growth, division and up-take). Bacteria interact via consumption. We set the exact Monte Carlo simulation algorithm of this model and its mathematical representation as a stochastic process. We prove the convergence of this process to the solution of an integro-differential equation when the population size tends to infinity. Finally, we propose several numerical simulations

    Smart Change in Strategy: IBM‘s Response to Challenging Times

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    International Business Machines, or IBM, has been an indisputable force in the communications industry, leading the world into the modern, global technological age. Currently, IBM has revamped its business paradigm, allocating the majority of its resources to consulting work and data analyses rather than manufacturing as it had done so in the past — for the primary objectives of optimizing existing assets, resolving problems of burgeoning cities and beleaguered governments, and enhancing peoples‘ lives in a sustainable way
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