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Datix
2015
Computer communication review
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Nikolaos Papailiou was supported by IKY fellowships of excellence for postgraduate studies in Greece -SIEMENS program. ...
doi:10.1145/2831347.2831351
fatcat:yd7422imkvb5valy7noimhcdcu
Uncertain Graph Sparsification
[article]
2017
arXiv
pre-print
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Uncertain graphs are prevalent in several applications including communications systems, biological databases and social networks. The ever increasing size of the underlying data renders both graph storage and query processing extremely expensive. Sparsification has often been used to reduce the size of deterministic graphs by maintaining only the important edges. However, adaptation of deterministic sparsification methods fails in the uncertain setting. To overcome this problem, we introduce
arXiv:1611.04308v4
fatcat:g534ej7hhrhn3f3hg2arzazzg4
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... e first sparsification techniques aimed explicitly at uncertain graphs. The proposed methods reduce the number of edges and redistribute their probabilities in order to decrease the graph size, while preserving its underlying structure. The resulting graph can be used to efficiently and accurately approximate any query and mining tasks on the original graph. An extensive experimental evaluation with real and synthetic datasets illustrates the effectiveness of our techniques on several common graph tasks, including clustering coefficient, page rank, reliability and shortest path distance.
H2RDF
2012
Proceedings of the 21st international conference companion on World Wide Web - WWW '12 Companion
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In this work we present H2RDF , a fully distributed RDF store that combines the MapReduce processing framework with a NoSQL distributed data store. Our system features two unique characteristics that enable efficient processing of both simple and multi-join SPARQL queries on virtually unlimited number of triples: Join algorithms that execute joins according to query selectivity to reduce processing; and adaptive choice among centralized and distributed (MapReduce-based) join execution for fast
doi:10.1145/2187980.2188058
dblp:conf/www/PapailiouKTK12
fatcat:6vdxhwgvhje23izc5aizmqpwxu
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... uery responses. Our system efficiently answers both simple joins and complex multivariate queries and easily scales to 3 billion triples using a small cluster of 9 worker nodes. H2RDF outperforms state-of-the-art distributed solutions in multi-join and nonselective queries while achieving comparable performance to centralized solutions in selective queries. In this demonstration we showcase the system's functionality through an interactive GUI. Users will be able to execute predefined or custom-made SPARQL queries on datasets of different sizes, using different join algorithms. Moreover, they can repeat all queries utilizing a different number of cluster resources. Using real-time cluster monitoring and detailed statistics, participants will be able to understand the advantages of different execution schemes versus the input data as well as the scalability properties of H2RDF over both the data size and the available worker resources.
H2RDF+
2014
Proceedings of the 2014 ACM SIGMOD international conference on Management of data - SIGMOD '14
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The proliferation of data in RDF format has resulted in the emergence of a plethora of specialized management systems. While the ability to adapt to the complexity of a SPARQL query -given their inherent diversity -is crucial, current approaches do not scale well when faced with substantially complex, non-selective joins, resulting in exponential growth of execution times. In this demonstration we present H2RDF+, an RDF store that efficiently performs distributed Merge and Sort-Merge joins
doi:10.1145/2588555.2594535
dblp:conf/sigmod/PapailiouTKKK14
fatcat:hlui2tfwlrgxjcfmowkmipnvv4
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... a multipleindex scheme over HBase indexes. Through a greedy planner that incorporates our cost-model, it adaptively commands for either single or multi-machine query execution based on join complexity. In this paper, we present its key scientific contributions and allow participants to interact with an H2RDF+ deployment over a Cloud infrastructure. Using a web-based GUI we allow users to load different datasets (both real and synthetic), apply any query (custom or predefined) and monitor its execution. By allowing real-time inspection of cluster status, response times and committed resources the audience will evaluate the validity of H2RDF+'s claims and perform direct comparisons to two other stateof-the-art RDF stores.
IReS
2015
Proceedings of the 2015 ACM SIGMOD International Conference on Management of Data - SIGMOD '15
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Nikolaos Papailiou has received funding from IKY fellowships of excellence for postgraduate studies in Greece -SIEMENS program. ...
doi:10.1145/2723372.2735377
dblp:conf/sigmod/DokaPTMK15
fatcat:5dyeik3d45esje2mbqmwravm4q
PANIC: Modeling Application Performance over Virtualized Resources
2015
2015 IEEE International Conference on Cloud Engineering
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Nikolaos Papailiou has received funding from IKY fellowships of excellence for postgraduate studies in Greece -SIEMENS program. ...
doi:10.1109/ic2e.2015.27
dblp:conf/ic2e/GiannakopoulosT15
fatcat:6pcq75f7avhkpgqygafrmdmi5u
Mix 'n' match multi-engine analytics
2016
2016 IEEE International Conference on Big Data (Big Data)
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Papailiou has received funding from IKY fellowships of excellence for postgraduate studies in Greece -SIEMENS program. ...
doi:10.1109/bigdata.2016.7840605
dblp:conf/bigdataconf/DokaPGTK16
fatcat:nimpr3poqfhapgxssfoulvva6u
CELAR: Automated application elasticity platform
2014
2014 IEEE International Conference on Big Data (Big Data)
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Nikolaos Papailiou has received funding from IKY fellowships of excellence for postgraduate studies in Greece -SIEMENS program. ...
doi:10.1109/bigdata.2014.7004481
dblp:conf/bigdataconf/GiannakopoulosPMKTK14
fatcat:wlwam7xvmvfr7lamsmh5bflgoy
Graph-Aware, Workload-Adaptive SPARQL Query Caching
2015
Proceedings of the 2015 ACM SIGMOD International Conference on Management of Data - SIGMOD '15
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Papailiou has received funding from IKY fellowships of excellence for postgraduate studies in Greece -SIEMENS program. ...
10 Average query response times for W1, W2, W3 and W4
Figure 11 : 11 Effectiveness of caching techniques
Figure 12 : 12 Cache performance for different dataset, caching policies and cache size
Nikolaos ...
doi:10.1145/2723372.2723714
dblp:conf/sigmod/PapailiouTKK15
fatcat:t4qgqvxt7ncu3gof4c2bsbsg7y
Morbid Obesity and Sleeve Gastrectomy: How Does It Work?
2010
Obesity Surgery
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Laparoscopic sleeve gastrectomy is known to be a safe and effective procedure for treating morbid obesity and is performed with increasing frequency both in Europe and the USA. Despite its broad use, many questions about the remaining gastric tube diameter, its long-term efficacy, its effects on gastric emptying, and the hormones involved still remain to be answered. In order to use such a relatively new surgical procedure wisely, it is essential for every surgeon and physician to understand
doi:10.1007/s11695-010-0148-5
pmid:20383753
fatcat:zjsz4s7efzbojozy54fzax7xuy
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... sleeve gastrectomy acts in obesity and what its potential benefits on the patients' metabolism are. This review focuses on the most important pathophysiologic questions referred to sleeve gastrectomy on the literature so far, in an attempt to evaluate the different issues still pending on the subject.
AAA Rupture and Psoas Hematoma due to Type II Endoleak from Inferior Mesenteric Artery "Unusual" Collaterals
2017
Case Reports in Vascular Medicine
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Although endovascular aneurysm repair (EVAR) in the abdominal aorta has reduced the perioperative mortality when compared with open repair, the need for reintervention after complications such as endoleak may be presented in up to 20% of the cases. Type II endoleak from branch vessels is often benign but can potentially be associated with progressive abdominal aortic aneurysm growth and sac expansion. We present a rare case of a patient who presented with sac expansion and psoas hematoma due to
doi:10.1155/2017/8607437
pmid:28634567
pmcid:PMC5467359
fatcat:43jh2grys5garixgvz2efkv7tu
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... Type II endoleak from "unusual" collaterals of IMA and was treated successfully with endoleak microembolization and percutaneous decompression of the hematoma.
Automatic scaling of selective SPARQL joins using the TIRAMOLA system
2012
Proceedings of the 4th International Workshop on Semantic Web Information Management - SWIM '12
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Modern cloud infrastructures based on virtual hardware provide new opportunities and challenges for developers and system administrators alike. Most notable is the promise of resource elasticity, whereby the infrastructure can increase or decrease in size based on demand. Utilizing elastic resources, applications can provide better quality of service and reduce cost by only paying for the required amount of resources. In this work, we extensively study the performance of some popular NoSQL
doi:10.1145/2237867.2237868
dblp:conf/sigmod/AngelouPKTK12
fatcat:emc6ulbbf5eelbo3bqsgtga6h4
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... ases over an elastic cloud infrastructure. NoSQL databases focus on analytical processing of large scale datasets, offering increased scalability over commodity hardware. We then proceed to describe TIRA-MOLA, a cloud-enabled framework for automatic provisioning of elastic resources on any NoSQL platform. Our system administers cluster resources (VMs) according to useror application-specified constraints through an expandable monitoring and command-issuing module. Users can easily modify resizing policies, based on application-specific metrics and thus fully utilize the elasticity of the underlying infrastructure. As a realistic use-case, we apply this framework on top of a fully distributed RDF store backed by an elastic NoSQL database. Letting TIRAMOLA manage the number of committed resources results in automated cluster resize actions and throughput maximization, while application experts need only provide simple elasticity rules.
Analysing and Enriching Focused Semantic Web Archives for Parliament Applications
2014
Future Internet
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Nikolaos Papailiou has received funding from IKY fellowships of excellence for postgraduate studies in Greece, SIEMENS program.
Author Contributions All authors contributed equally to the paper. ...
doi:10.3390/fi6030433
fatcat:jasz3i3sofhipellazgoo4cvre
Scalable Indexing and Adaptive Querying of RDF Data in the cloud
2014
Proceedings of Semantic Web Information Management on Semantic Web Information Management - SWIM'14
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Efficient RDF data management systems are central to the vision of the Semantic Web. The enormous increase in both user and machine generated content dictates for scalable solutions in triple data stores. Current systems manage to decentralize some or all the stages of RDF data management, scaling to arbitrarily large numbers of triples. Yet, these systems prove highly inflexible in adjusting their behavior relative to the query in hand. Queries over triple data include multiple joins with
doi:10.1145/2630602.2630603
dblp:conf/sigmod/PapailiouTKKK14a
fatcat:7asq5xr43fbazklagzowxyynue
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... ng degrees of selectivity and cost. In many cases, a join performed on a single centralized computer node is highly preferable. Thus, both informed query planning and adaptive join execution are necessary to gain optimal performance in both selective and non selective queries. Towards that direction, we describe H2RDF+, an RDF store that efficiently performs distributed joins over a multiple index scheme. H2RDF+ materializes 6 RDF indexes and detailed statistics using HBase. In this work, we emphasize on our novel, scalable and efficient MapReduce indexing process that allows H2RDF+ to handle arbitrarily large RDF datasets. Aggressive byte-level compression is also extensively used to reduce the storage space requirements of the system. H2RDF+ can also adaptively process both complex and selective queries by adaptively choosing the amount of resources allocated for each join, based on join complexity estimated through index statistics.
Aldosterone synthase deficiency type II: an unusual presentation of the first Greek case reported with confirmed genetic analysis
2020
Endocrine Regulations
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AbstractObjective. Aldosterone synthase deficiency (ASD) is a rare, autosomal recessive inherited disease with an overall clinical phenotype of failure to thrive, vomiting, severe dehydration, hyperkalemia, and hyponatremia. Mutations in the CYP11B2 gene encoding aldosterone synthase are responsible for the occurrence of ASD. Defects in CYP11B2 gene have only been reported in a limited number of cases worldwide. Due to this potential life-threatening risk, comprehensive hormonal investigation
doi:10.2478/enr-2020-0025
pmid:32857717
fatcat:taxbrle2wfhyri3ddm6kusmpsa
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... llowed by genetic confirmation is essential for the clinical management of offsprings.Case presentation. We herein describe an unusual case of ASD type II in a neonate with faltering growth as a single presenting symptom. To our knowledge, this is the first Greek case of ASD type II reported with confirmed genetic analysis. Next generation sequencing of her DNA revealed the homozygous mutation p.T185I (ACC-ATC) (c.554C>T) (g.7757C>T) in exon 3 of the CYP11B2 gene in the neonate, inherited from both parents who were heterozygotes for the mutation.Conclusions. Physicians handling neonates with faltering growth, particularly in the initial six weeks of life, should be suspicious of mineralocorticoid insufficiency either as isolated hypoaldosteronism or in the context of congenital adrenal hyperplasia. Essential investigations should be performed and appropriate treatment should be administered promptly without awaiting for the hormonal profile results. Interpretation of the clinical picture and the hormonal profile will guide the analysis of candidate genes. Primary selective hypoaldosteronism is a rare, life threatening disease, but still with an unknown overall population impact. Thus, reporting cases with confirmed gene mutations is of major importance.
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