Adaptive Partitioning for Large-Scale Dynamic Graphs

Abstract—In the last years, large-scale graph processing has gained increasing attention, with most recent systems placing particular emphasis on latency. One possible technique to improve runtime performance in a distributed graph processing system is to reduce network communication. The most notable way to achieve this goal is to partition the graph by minimizing the num-ber of edges that connect vertices assigned to different machines, while keeping the load balanced. However, real-world graphs are highly dynamic, with vertices and edges being constantly added and removed. Carefully updating the partitioning of the graph to reflect these changes is necessary to avoid the introduction of an extensive number of cut edges, which would gradually worsen computation performance. In this paper we show that performance degradation in dynamic graph processing systems can be avoided by adapting continuously the graph partitions as the graph changes. We present a novel highly scalable adaptive partitioning strategy, and show a number of refinements that make it work under the constraints of a large-scale distributed system. The partitioning strategy is based on iterative vertex migrations, relying only on local information. We have implemented the technique in a graph processing system, and we show through three real-world scenarios how adapting graph partitioning reduces execution time by over 50 % when compared to commonly used hash-partitioning. I

The swastika as representation of the Sun of Helios and Mithras

At the 20th International Conference of the European Society for Astronomy in Cul- ture, held in Slovenia in 2012, Reza Assasi (2013) presented the paper ‘Swastika: The For- gotten Constellation Representing the Chariot of Mithras’, in which he identified Mithras and his quadriga with the constellation Draco, centre of the zodiac in the map of the stars. Thus he proposed a new interpretation that contradicted that accepted by researchers of the Mithraic religion who associate Mithras with the sun. This article aims to show that, contrary to this new interpretation, Mithras should still be identified with the solar deity. Mithraic iconography and liturgy is analysed in the present work, paying special attention to the relationship between the two solar deities Helios and Mithras. The context in which the swastika is depicted is analysed, demon- strating that it never represented a constellation but instead represented the sun. We fol- low the theory of David Ulansey (1994), which asserts that Mithras should be identified with the “hypercosmic sun”, the sphere of fire which Greek philosophers located beyond the starry heavens

Medical Aspects of mTOR Inhibition in Kidney Transplantation

The advances in transplant immunosuppression have reduced substantially the incidence of kidney graft rejection. In recent years, the focus has moved from preventing rejection to preventing the long-term consequences of long-standing immunosuppression, including nephrotoxicity induced by calcineurin inhibitors (CNI), as well as infectious and neoplastic complications. Since the appearance in the late 1990s of mTOR inhibitors (mTORi), these unmet needs in immunosuppression management could be addressed thanks to their benefits (reduced rate of viral infections and cancer). However, management of side effects can be troublesome and hands-on experience is needed. Here, we review all the available information about them. Thanks to all the basic, translational and clinical research achieved in the last twenty years, we now use mTORi as de novo immunosuppression in association with CNI. Another possibility is represented by the conversion of either CNI or mycophenolate (MPA) to an mTORi later on after transplantation in low-risk kidney transplant recipients. © 2022 by the authors

Reusable model transformation components with bentō

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-21155-8_5Building high-quality transformations that can be used in real projects is complex and time-consuming. For this reason, the ability to reuse existing transformations in different, unforeseen scenarios is very valuable. However, there is scarce tool support for this task. This paper presents bentō, a tool which supports the development and execution of reusable transformation components. In bentō, a reusable transformation is written as a regular ATL transformation, but it uses concepts as meta-models. Reuse is achieved by binding such concepts to meta-models, which induces the transformation adaptation. Moreover, composite components enable chaining transformations, and it is possible to convert an existing transformation into a reusable component. Bentō is implemented as an Eclipse plug-in, available as free software.This work was supported by the Spanish Ministry of Economy and Competitivity with project Go-Lite (TIN2011-24139), the R&D programme of the Madrid Region with project (SICOMORO S2013/ICE-3006), and the EU commission with project MONDO (FP7-ICT 2013-10, #611125)

Deploying Large-Scale Datasets on-Demand in the Cloud: Treats and Tricks on Data Distribution

Public clouds have democratised the access to analytics for virtually any institution in the world. Virtual Machines (VMs) can be provisioned on demand, and be used to crunch data after uploading into the VMs. While this task is trivial for a few tens of VMs, it becomes increasingly complex and time consuming when the scale grows to hundreds or thousands of VMs crunching tens or hundreds of TB. Moreover, the elapsed time comes at a price: the cost of provisioning VMs in the cloud and keeping them waiting to load the data. In this paper we present a big data provisioning service that incorporates hierarchical and peer-to-peer data distribution techniques to speed-up data loading into the VMs used for data processing. The system dynamically mutates the sources of the data for the VMs to speed-up data loading. We tested this solution with 1000 VMs and 100 TB of data, reducing time by at least 30 % over current state of the art techniques. This dynamic topology mechanism is tightly coupled with classic declarative machine configuration techniques (the system takes a single high-level declarative configuration file and configures both software and data loading). Together, these two techniques simplify the deployment of big data in the cloud for end users who may not be experts in infrastructure management. Index Terms—Large-scale data transfer, flash crowd, big data, BitTorrent, p2p overlay, provisioning, big data distribution I

xDGP: A Dynamic Graph Processing System with Adaptive Partitioning

13 pagesMany real-world systems, such as social networks, rely on mining efficiently large graphs, with hundreds of millions of vertices and edges. This volume of information requires partitioning the graph across multiple nodes in a distributed system. This has a deep effect on performance, as traversing edges cut between partitions incurs a significant performance penalty due to the cost of communication. Thus, several systems in the literature have attempted to improve computational performance by enhancing graph partitioning, but they do not support another characteristic of real-world graphs: graphs are inherently dynamic, their topology evolves continuously, and subsequently the optimum partitioning also changes over time. In this work, we present the first system that dynamically repartitions massive graphs to adapt to structural changes. The system optimises graph partitioning to prevent performance degradation without using data replication. The system adopts an iterative vertex migration algorithm that relies on local information only, making complex coordination unnecessary. We show how the improvement in graph partitioning reduces execution time by over 50%, while adapting the partitioning to a large number of changes to the graph in three real-world scenarios

The impact of non–local birds on yellow–legged gulls (Larus michahellis) in the Bay of Biscay: a dump–based assessment

El impacto de los individuos no locales en la gaviota patiamarilla (Larus michahellis) en el Golfo de Vizcaya: una estimación a partir de vertederos Es necesario comprender la forma en que los animales explotan los recursos tróficos de origen no natural, como es el caso de los vertederos, desde múltiples perspectivas como la conservación, la dinámica de poblaciones y la gestión. Son varias las especies de gaviotas depredadoras de gran tamaño (Larus sp.) las que indudablemente se benefician de utilizar los vertederos. La gaviota patiamarilla (L. michahellis) es la especie de gaviota más abundante del Paleártico sudoccidental y el rápido crecimiento de sus poblaciones hasta al menos la primera década del siglo XXI se debe, parcialmente, al aumento de vertederos. El Golfo de Vizcaya es una zona que alberga gaviotas locales residentes y gaviotas invernantes procedentes de otras zonas. A partir de los datos obtenidos en censos y avistamientos de gaviotas marcadas con anillas de color que se recopilaron durante un periodo de ocho años en cuatro vertederos situados en un radio de 60 km desde las colonias de cría en Gipuzkoa, se trató de responder a las siguientes cuestiones: (1) el origen de las gaviotas que usan los vertederos en el Golfo de Vizcaya; (2) el impacto de los individuos locales y no locales en estos vertederos; (3) la posibilidad de que exista un uso distinto según la edad y (4) la posibilidad de que haya fluctuaciones estacionales en el uso de los vertederos. Las gaviotas en los vertederos estudiados provienen de las colonias costeras cercanas de Gipuzkoa, la zona atlántica de la península Ibérica, la región mediterránea y otras zonas como la costa atlántica de Francia y las colonias continentales (Navarra y Alemania). Parece que los vertederos de nuestro estudio fueron utilizados, principalmente, por aves locales.Understanding how animals exploit non–natural feeding sources such as garbage dumps is necessary from many perspectives, including conservation, and population dynamics and management. Several large predatory gulls (Larus spp.) are among the species which most clearly benefit from using dumps. The yellow–legged gull (L. michahellis) is the most abundant gull in the southwestern Palaearctic, and its fast population increase until at least the 2000s was partly due large waste dumps becoming more numerous. The Bay of Biscay is an area that hosts resident local and also wintering non–local yellow–legged gulls. Using data collected over a period of eight years (bird counts, identification of colour–ringed individuals) at four dumps situated within a 60–km radius from the colonies of Gipuzkoa (southwestern Bay of Biscay), we aimed to answer: (1) the origin of gulls using dumps at the Bay of Biscay; (2) the impact of local and non–local gulls at these dumps; (3) the possible age–dependent use of these sites; and (4) the possible seasonal fluctuations in the use of dumps by gulls. Gulls in our area (study dumps) came from nearby colonies in Gipuzkoa, Atlantic Iberia, the Mediterranean region, and other areas such as Atlantic France and inland colonies (Navarra, Germany). Our study dumps seemed to be used mostly by local gulls.El impacto de los individuos no locales en la gaviota patiamarilla (Larus michahellis) en el Golfo de Vizcaya: una estimación a partir de vertederos Es necesario comprender la forma en que los animales explotan los recursos tróficos de origen no natural, como es el caso de los vertederos, desde múltiples perspectivas como la conservación, la dinámica de poblaciones y la gestión. Son varias las especies de gaviotas depredadoras de gran tamaño (Larus sp.) las que indudablemente se benefician de utilizar los vertederos. La gaviota patiamarilla (L. michahellis) es la especie de gaviota más abundante del Paleártico sudoccidental y el rápido crecimiento de sus poblaciones hasta al menos la primera década del siglo XXI se debe, parcialmente, al aumento de vertederos. El Golfo de Vizcaya es una zona que alberga gaviotas locales residentes y gaviotas invernantes procedentes de otras zonas. A partir de los datos obtenidos en censos y avistamientos de gaviotas marcadas con anillas de color que se recopilaron durante un periodo de ocho años en cuatro vertederos situados en un radio de 60 km desde las colonias de cría en Gipuzkoa, se trató de responder a las siguientes cuestiones: (1) el origen de las gaviotas que usan los vertederos en el Golfo de Vizcaya; (2) el impacto de los individuos locales y no locales en estos vertederos; (3) la posibilidad de que exista un uso distinto según la edad y (4) la posibilidad de que haya fluctuaciones estacionales en el uso de los vertederos. Las gaviotas en los vertederos estudiados provienen de las colonias costeras cercanas de Gipuzkoa, la zona atlántica de la península Ibérica, la región mediterránea y otras zonas como la costa atlántica de Francia y las colonias continentales (Navarra y Alemania). Parece que los vertederos de nuestro estudio fueron utilizados, principalmente, por aves locales