2,080 research outputs found

    Differential Diagnosis of a Left Atrial Mass: Role of 3D Transesophageal Echocardiography

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    An 81-year-old female patient was admitted to our clinic due to an episode of loss of consciousness... On admission the clinical examination revealed bradyarrhythmia with normal heart sounds, a soft systolic apical murmur consistent with mild mitral regurgitation and no signs of pulmonary congestion... A transthoracic echocardiogram showed a left ventricle of normal dimensions with a preserved systolic function and a mass inside the left atrium... (excerpt

    An Aggregation-Based Algebraic Multigrid Method with Deflation Techniques and Modified Generic Factored Approximate Sparse Inverses

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    In this paper, we examine deflation-based algebraic multigrid methods for solving large systems of linear equations. Aggregation of the unknown terms is applied for coarsening, while deflation techniques are proposed for improving the rate of convergence. More specifically, the V-cycle strategy is adopted, in which, at each iteration, the solution is computed by initially decomposing it utilizing two complementary subspaces. The approximate solution is formed by combining the solution obtained using multigrids and deflation. In order to improve performance and convergence behavior, the proposed scheme was coupled with the Modified Generic Factored Approximate Sparse Inverse preconditioner. Furthermore, a parallel version of the multigrid scheme is proposed for multicore parallel systems, improving the performance of the techniques. Finally, characteristic model problems are solved to demonstrate the applicability of the proposed schemes, while numerical results are given

    Cardiac Tumors

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    Cardiac tumors represent a relatively rare, yet challenging diagnosis. Secondary tumors are far more frequent than primary tumors of the heart. The majority of primary cardiac tumors is benign in origin, with primary malignant tumors accounting for 25% of cases. Metastatic tumors usually arise from lung, breast, renal cancer, melanomas, and lymphomas. Clinical manifestations of cardiac tumors depend on the size and location of the mass and the infiltration of adjacent tissues rather than the type of the tumor itself. Echocardiography is the main diagnostic tool for the detection of a cardiac mass. Other imaging modalities (C-MRI, C-CT, 3D Echo) may offer further diagnostic information and the establishment of the diagnosis is made with histological examination. Management depends on the type of the tumor and the symptomatology of the patient

    A survey on cost-effective context-aware distribution of social data streams over energy-efficient data centres

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    Social media have emerged in the last decade as a viable and ubiquitous means of communication. The ease of user content generation within these platforms, e.g. check-in information, multimedia data, etc., along with the proliferation of Global Positioning System (GPS)-enabled, always-connected capture devices lead to data streams of unprecedented amount and a radical change in information sharing. Social data streams raise a variety of practical challenges, including derivation of real-time meaningful insights from effectively gathered social information, as well as a paradigm shift for content distribution with the leverage of contextual data associated with user preferences, geographical characteristics and devices in general. In this article we present a comprehensive survey that outlines the state-of-the-art situation and organizes challenges concerning social media streams and the infrastructure of the data centres supporting the efficient access to data streams in terms of content distribution, data diffusion, data replication, energy efficiency and network infrastructure. We systematize the existing literature and proceed to identify and analyse the main research points and industrial efforts in the area as far as modelling, simulation and performance evaluation are concerned

    Electronic recording of lifetime locomotory activity patterns of adult medflies.

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    Age-specific and diurnal patterns of locomotory activity, can be considered as biomarkers of aging in model organisms and vary across the lifetime of individuals. Τhe Mediterranean fruit fly (medfly), Ceratitis capitata, is a commonly used model-species in studies regarding demography and aging. In the present study, we introduce a modification of the automated locomotory activity electronic device LAM25system (Locomotory Activity Monitor)-Trikinetics, commonly used in short time studies, to record the daily locomotory activity patterns of adult medflies throughout the life. Additionally, fecundity rates and survival of adult medflies were recorded. Male and female medflies were kept in the system tubes and had access to an agar-based gel diet, which provided water and nutrients. The locomotory activity was recorded at every minute by three monitors in the electronic device. The locomotory activity of females was higher than that of males across the different ages. For both sexes locomotory rates were high during the first 20 days of the adult life and decreased in older ages. The activity of males was high in the morning and late afternoon hours, while that of females was constantly high throughout the photophase. Negligible locomotory activity was recorded for both sexes during the nighttime. Males outlived females. Fecundity of females was higher in younger ages. Our results support the adoption of LAM25system in studies addressing aging of insects using medfly as a model organism

    Simulating fog and edge computing scenarios: an overview and research challenges

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    The fourth industrial revolution heralds a paradigm shift in how people, processes, things, data and networks communicate and connect with each other. Conventional computing infrastructures are struggling to satisfy dramatic growth in demand from a deluge of connected heterogeneous endpoints located at the edge of networks while, at the same time, meeting quality of service levels. The complexity of computing at the edge makes it increasingly difficult for infrastructure providers to plan for and provision resources to meet this demand. While simulation frameworks are used extensively in the modelling of cloud computing environments in order to test and validate technical solutions, they are at a nascent stage of development and adoption for fog and edge computing. This paper provides an overview of challenges posed by fog and edge computing in relation to simulation

    On issues concerning Cloud environments in scope of scalable multi-projection methods

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    Over the last decade, Cloud environments have gained significant attention by the scientific community, due to their flexibility in the allocation of resources and the various applications hosted in such environments. Recently, high performance computing applications are migrating to Cloud environments. Efficient methods are sought for solving very large sparse linear systems occurring in various scientific fields such as Computational Fluid Dynamics, N-Body simulations and Computational Finance. Herewith, the parallel multi-projection type methods are reviewed and discussions concerning the implementation issues for IaaS-type Cloud environments are given. Moreover, phenomena occurring due to the "noisy neighbor" problem, varying interconnection speeds as well as load imbalance are studied. Furthermore, the level of exposure of specialized hardware residing in modern CPUs through the different layers of software is also examined. Finally, numerical results concerning the applicability and effectiveness of multi-projection type methods in Cloud environments based on OpenStack are presented

    Evaluation of physiological characteristics as selection criteria for drought tolerance in maize inbred lines and their hybrids

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    Improvement for maize drought tolerance has always been a significantobjective for breeders and plant physiologists. Nowadays, climate change sets new challenges to major crop adaptation at stressful environments. For such a purpose, the measurement of physiological traits related to maize response to drought might prove to be useful indices. The objective of the present study was to establish whether the physiological traits can be used as reliable physiological markers to evaluate the performance of parental genotypes and their hybrids under both dry and normally watered conditions, and under two densities an ultra-low density (ULD) and a normal dense stand (DS). Thirty (30) maize inbred lines and 30 single-crosses among them were evaluated across three diverse locations in Greece. The ULD was 0.74 plants/m-2, while the DS comprised 4.44 plants m-2 in the water deficitregime, and 6.67 and 7.84 plants m-2 in the normal water treatment for lines and hybrids, respectively. There was a very good association between the physiological characteristics studied and grain yield under the ultra-low density and especially for inbred lines. It was shown that the physiological characteristics can facilitate the selection of stress-adaptive genotypes under the low-density conditions and may permit modern maize to be grown at a wider range of environments. At the normal densities such a possibility was not evidenced since physiological parameters and yield did not correlate for either parents or hybrid
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