Grid-Brick Event Processing Framework in GEPS

Experiments like ATLAS at LHC involve a scale of computing and data management that greatly exceeds the capability of existing systems, making it necessary to resort to Grid-based Parallel Event Processing Systems (GEPS). Traditional Grid systems concentrate the data in central data servers which have to be accessed by many nodes each time an analysis or processing job starts. These systems require very powerful central data servers and make little use of the distributed disk space that is available in commodity computers. The Grid-Brick system, which is described in this paper, follows a different approach. The data storage is split among all grid nodes having each one a piece of the whole information. Users submit queries and the system will distribute the tasks through all the nodes and retrieve the result, merging them together in the Job Submit Server. The main advantage of using this system is the huge scalability it provides, while its biggest disadvantage appears in the case of failure of one of the nodes. A workaround for this problem involves data replication or backup.Comment: 6 pages; document for CHEP'03 conferenc

As estrategias de aprendizagen nas diferentes abordagens ao estudo: uma investigação com alunos do ensino secundario

[Resumo] Nas duas últimas décadas, numa linha cognitivo-construtivista do ensinoa prendizagem, tem-se valorizado o papel do aluno na aprendizagem. As abordagens ao estudo (Biggs, 1990) e as estratégias de autoregulacão da aprendizagem (Zimmerman, 1990) exemplificam essa perspectiva de análise. Os alunos mais eficientes na aprendizagem adoptam estratégias de mais activas e adaptadas as diferentes exigencias dos contextos e tarefas de aprendizagem. Neste artigo, tomando urna amostra de 558 alunos do Ensino Secundário em Portugal, procura-se conhecer as estratégias de aprendizagem mais usadas e a sua correlacão com as classificaçoes escolares. As correlaçoes encontradas entre as diferentes abordagens ao estudo ou as estratégias de auto-regulac;ao da aprendizagem com as classificaçoes escolares dos alunos, mesmo que estatisticamente significativas, foram reduzida

Proveniência geológica dos esteios de antas no Freixo-Redondo e em Monforte, Centro-Sul de Portugal

O projeto geoarqueológico MEGAGEO relaciona a distribuição de antas com os seus materiais de construção e a paisagem geológica, nas áreas do Freixo-Redondo e em Monforte. Estas áreas apresentam contextos geológicos que permitem uma abordagem interdisciplinar de caracterização e proveniência de megálitos. A área do Freixo-Redondo é constituída por rochas metamórficas (gnaisses, micaxistos, filitos e metagrauvaques), que são intruídas pelo maciço ígneo do Redondo [2]. Este, corresponde a um corpo granodiorítico, com uma pequena intrusão de gabro/diorito e frequentes encraves de rochas encaixantes. As antas estão preferencialmente implantadas no substrato granodiorítico, em torno da intrusão de gabro/diorito, ou nos gnaisses encaixantes e são essencialmente constituídas por granodioritos. Destacam-se deste contexto as antas de Godinhos e Candeira, que se localizam mais a norte, na auréola de metamorfismo (gnaisses, xistos porfiroclásticos, micaxistos e granitos moscovíticos) e que são essencialmente constituídas por rochas metamórficas. A área de Monforte é caracterizada pelo granito de Monforte, que corresponde a um granito rosa de grão médio a grosseiro, que intrui e metamorfiza por contacto o encaixante formado por gneisses, metapelitos, anfibolitos, rochas carbonatadas e calcossilicatadas [1]. As antas estão implantadas quer no granito quer no encaixante e são constituídas por granito, gnaisses, rochas carbonatadas e corneanas calcossilicatadas. Em ambas as áreas foram recolhidos dados de natureza arqueológica e realizados levantamentos de campo, envolvendo a caracterização dos esteios e dos prováveis afloramentos de proveniência. Após recolha de amostras representativas dos esteios e dos prováveis afloramentos de proveniência, realizou-se análise petrográfica pelos métodos convencionais de microscopia de luz polarizada e análises semi-quantitativas por SEM-EDS. Por último, foi efetuada a caracterização geoquímica de todas as amostras envolvendo análises geoquímicas elementares (ICP-MS). Os resultados obtidos, permitiram de um modo geral relacionar esteios com os afloramentos selecionados e confirmar a proveniência dos esteios. Para a região do Freixo-Redondo obtiveram-se, em média, distâncias menores aos afloramentos quando comparado com a região de Monforte

211007

This work will demonstrate a new flavor of the RA-TDMA set of protocols, namely RA-TDMAs+, which uses IEEE-802.11 (WiFi) COTS hardware in ad-hoc mode to set up a dynamic mesh network of mobile nodes with highbandwidth. The protocol uses topology tracking to configure the TDMA frame and robust relative synchronization to define the TDMA slots without resorting to a global clock and in the presence of interfering traffic. The demo will set up a small-scale testbed using COTS hardware, thus evidencing the feasibility of the approach, and it will show 1clive plots 1d of the temporal (synchronization) and topological views of the network.This work was partially supported by National Funds through FCT/MCTES (Portuguese Foundation for Science and Technology), within the CISTER Research Unit (UIDB/04234/2020); by the Operational Competitiveness Programme and Internationalization (COMPETE 2020) under the PT2020 Agreement, through the European Regional Development Fund (ERDF); also by FCT and the ESF (European Social Fund) through the Regional Operational Programme (ROP) Norte 2020, under PhD grant 2020.06685.BD; and within the AQUAMON project (PTDC/CCI-COM/30142/2017).info:eu-repo/semantics/publishedVersio

220604

This research proposes a novel minimal-overlap centrality-driven gateway designation method for real-time wireless sensor networks (WSNs). The goal is to enhance network schedulability by design, particularly, by exploiting the relationship between path node-overlaps and gateway designation. To this aim, we define a new metric termed minimal-overlap network centrality which characterizes the overall overlapping degree between all the active flows in the network when a given node is selected as gateway. The metric is then used to designate as gateway the node which produces the least overall number of path overlaps. For the purposes of evaluation, we assume a time-synchronized channel-hopping (TSCH) WSN under centralized earliest-deadline-first (EDF) scheduling and shortest-path routing. The assessment of the WSN traffic schedulability suggests our approach is dominant over classical network centrality metrics, namely, eigenvector, closeness, betweenness, and degree. Notably, it achieves up to 50% better schedulability than a degree centrality benchmark.This work was partially supported by National Funds through FCT/MCTES (Portuguese Foundation for Science and Technology), within the CISTER Research Unit (UIDB/04234/2020); by the Operational Competitiveness Programme and Internationalization (COMPETE 2020) under the PT2020 Agreement, through the European Regional Development Fund (ERDF); also by FCT and the ESF (European Social Fund) through the Regional Operational Programme (ROP) Norte 2020, under PhD grant 2020.06685.BDN/

Swash zone dynamics of coarse-grained beaches during energetic wave conditions

Coarse-grained beaches, such as pure gravel (PG), mixed sand-gravel (MSG) and composite (CSG) beaches, can be considered as one of the most resilient non-cohesive morpho-sedimentary coastal environments to energetic wave forcing (e.g., storms). The hydraulically-rough and permeable nature of gravel (D50 > 2 mm), together with the steep (reflective) beach face, provide efficient mechanisms of wave energy dissipation in the swash zone and provide a natural means of coastal defence. Despite their potential for shore protection very little is known about the response of these environments during high energetic wave conditions. Field measurements of sediment transport and hydrodynamics on coarse-grained beaches are difficult, because there are few instruments capable of taking direct measurements in an energetic swash zone in which large clasts are moving, and significant morphological changes occur within a short period of time. Remote sensing methods emerge in this context as the most appropriate solution for these types of field measurement. A new remote sensing method, based around a mid-range (~ 50 m) 2D laser-scanner was developed, which allows the collection of swash zone hydrodynamics (e.g., vertical and horizontal runup position, swash depth and velocity) and bed changes on wave-by-wave time scale. This instrument allowed the complete coverage of the swash zone on several coarse-grained beaches with a vertical accuracy of approximately 0.015 m and an average horizontal resolution of 0.07 m. The measurements performed with this new methodology are within the accuracy of traditional field techniques (e.g. video cameras, ultrasonic bed-level sensors or dGPS). Seven field experiments were performed between March 2012 and January 2014 on six different coarse-grained beaches (Loe Bar, Chesil, Slapton, Hayling Island, Westward Ho! and Seascale), with each deployment comprising the 2D laser-scanner together with complementary in-situ instrumentation (e.g., pressure transducer, ADV current meter). These datasets were used to explore the hydrodynamics and morphological response of the swash zone of these different environments under different energetic hydrodynamic regimes, ranging from positive, to zero, to negative freeboard regimes. With reference to the swash zone dynamics under storms with positive freeboard regimes (when runup was confined to the foreshore) it was found that extreme runup has an inverse relationship with the surf scaling parameter (=2Hs /gTptan2). The highest vertical runup excursions were found on the steepest beaches (PG beaches) and under long-period swell, while lower vertical runup excursions where linked to short-period waves and beaches with intermediate and dissipative surf zones, thus demonstrating that the contrasting degree of wave dissipation observed in the different types of surf zones is a key factor that control the extreme runup on coarse-grained beaches. Contrasting morphological responses were observed on the different coarse-grained beaches as a result of the distinct swash\surf zone hydrodynamics. PG beaches with narrow surf zone presented an asymmetric morphological response during the tide cycle (accretion during the rising and erosion during the falling tide) as a result of beach step adjustments to the prevailing hydrodynamics. On dissipative MSG and CSG beaches the morphological response was limited due to the very dissipative surf zone, while on an intermediate CSG beach significant erosion of the beach face and berm was observed during the entire tide cycle as a result of the absence of moderate surf zone wave dissipation and beach step dynamics. Fundamental processes related to the link between the beach step dynamics and the asymmetrical morphological response during the tidal cycle were for the first time measured under energetic wave conditions. During the rising tide the onshore shift of the breaking point triggers the onshore translation of the step and favors accretion (step deposit development), while during the falling tide the offshore translation of the wave breaking point triggers retreat of the step and favours backwash sediment transport (erosion of the step deposit). Under zero and negative freeboard storm regimes (when runup exceeds the crest of the barrier or foredune), field measurements complimented by numerical modelling (Xbeach-G) provide clear evidence that the presence of a bimodal wave spectrum enhances the vertical runup and can increase the likelihood of the occurrence of overtopping and overwash events over a gravel barrier. Most runup equations (e.g., Stockdon et al., 2006) used to predict the thresholds for storm impact regime (e.g., swash, overtopping and overwash) on barriers lack adequate characterisation of the full wave spectra; therefore, they may miss important aspects of the incident wave field, such as wave bimodality. XBeach-G allows a full characterization of the incident wave field and is capable of predicting the effect of wave spectra bimodality on the runup, thus demonstrating that is a more appropriate tool for predicting the storm impact regimes on gravel barriers. Regarding the definition of storm impact regimes on gravel barriers, it was found that wave period and wave spectra bimodality are key parameters that can affect significantly the definition of the thresholds for these different regimes. While short-period waves dissipate most of their energy before reaching the swash zone (due to breaking) and produce short runup excursions, long-period waves arrive at the swash zone with enhanced heights (due to shoaling) and break at the edge of the swash, thus promoting large runup excursions. When offshore wave spectrum presents a bimodal shape, the wave transformation on shallow waters favours the long period peak (even if the short-period peak is the most energetic offshore) and large runup excursions occur. XBeach-G simulations show that the morphological response of fine gravel barriers is distinct from coarse gravel barriers under similar overtopping conditions. While on coarser barriers overtopping regimes are expected to increase the crest elevation and narrow the barrier, on fine barriers sedimentation occurs on the back of the barrier and in the lower beach face. Such different sedimentation patterns are attributed to the different hydraulic conductivity of the different sediment sizes which control the amount of flow dissipation (due to infiltration) and, therefore, the capacity of the flow to transport sediment across and over the barrier crest. The present findings have significantly improved our conceptual understanding of the response of coarse-grained beaches during storms. A new field technique to measure swash dynamics in the field was developed during this thesis and has great potential to become widely used in a variety of coastal applications.EPSR

Real-Time Communication Support for Over-water Wireless Multi-hop Networks

https://www.bsc.es/education/predoctoral-phd/doctoral-symposium/7th-bsc-so-doctoral-symposiumThe prospect scenario for wireless communications and networking technologies in aquatic environments is nowadays promising. The growing interest around this subject in the last decades has recently been accelerated due to the more powerful capabilities of a number of sensing, control and communication devices. Moored, fixed, drifting, and vehicular nodes form now a rich ecosystem of autonomous embedded systems potentially connected in a multi-hop (and over-water) fashion, which demand innovative solutions to satisfy the ever-increasing requirements of reliability, bandwidth, latency and cost. The efforts in this direction, mostly as a result of the push from the Internet-of-Thing (IoT) and related communication paradigms, are now at an early stage, and thus still pose significant, technical and research challenges, especially from the perspective of communication and networking for applications involving real-time and/or multimedia networking traffic. In this research, we focus on the communication and networking aspects of over-water multi-hop networks aiming at support real-time and/or multimedia (audio/video) traffic using IEEE 802.11 (WiFi) commodity technologies. Special attention is devoted to the impact of cyclic water-level variations (such as tides and waves) on the overall network performance, and how an integrated approach to (i) network design, (ii) protocol adaptation and (iii) routing can contribute to mitigating such an issue.info:eu-repo/semantics/publishedVersio

JC virus in the pathogenesis of colorectal cancer, an etiological agent or another component in a multistep process?

JCV infection occurs early in childhood and last throughout life. JCV has been associated to colorectal cancer and might contribute to the cancer phenotype by several mechanisms. Among JCV proteins, particularly two of them, large T-antigen and agnoprotein, can interfere with cell cycle control and genomic instability mechanisms, but other viral proteins might also contribute to the process. Part of viral DNA sequences are detected in carcinoma lesions, but less frequently in adenomas, and not in the normal surrounding tissue, suggesting they are integrated in the host cell genome and these integrations have been selected; in addition viral integration can cause a gene, or chromosomal damage. The inflammatory infiltration caused by a local chronic viral infection in the intestine can contribute to the selection and expansion of a tumor prone cell in a cytokine rich microenvironment. JCV may not be the cause of colorectal cancer, but it can be a relevant risk factor and able to facilitate progression at one or several stages in tumor progression. JCV transient effects might lead to selective expansion of tumor cells. Since there is not a direct cause and effect relationship, JCV infection may be an alternative to low frequency cancer predisposition genes

Temporal behavior of Ethernet communications: impact of the operating system and protocol stack

Ethernet is currently the most widely used networking technology, spanning across many application domains including embedded systems. In this particular case, Ethernet is even used in many time-critical applications in which the delay induced by communication must be short and bounded. It is thus very important to understand the entire transmission process and assess its temporal behavior. There are a number of aspects to consider, including the network protocol, network topology, network elements and end devices. This paper aims at assessing the impact of the operating system and its protocol stack implementation in the end devices on the network temporal behavior. We studied four operating systems, namely a standard Ubuntu distribution with and without a real-time kernel patch, an embedded stripped down version of Linux and QNX Neutrino, and two hardware platforms, namely ordinary PCs and a single board computer based on an AVR32 CPU. We measured the Round Trip Delay (RTD) using RAW, UDP and TCP sockets to interface the protocol stack. We verified that on high computing power platforms the difference between the sockets is small but still significant in resource-constrained platforms. On the other hand, full featured general OSs present rather large worst-case delays. These can be reduced using real-time patches for those OSs, RTOSs, or even removing unnecessary modules, services and particularly, data intensive device drivers. We believe this study can be helpful for system designers as well as for teaching networks courses in embedded systems.Ethernet is currently the most widely used networking technology, spanning across many application domains including embedded systems. In this particular case, Ethernet is even used in many time-critical applications in which the delay induced by communication must be short and bounded. It is thus very important to understand the entire transmission process and assess its temporal behavior. There are a number of aspects to consider, including the network protocol, network topology, network elements and end devices. This paper aims at assessing the impact of the operating system and its protocol stack implementation in the end devices on the network temporal behavior. We studied four operating systems, namely a standard Ubuntu distribution with and without a real-time kernel patch, an embedded stripped down version of Linux and QNX Neutrino, and two hardware platforms, namely ordinary PCs and a single board computer based on an AVR32 CPU. We measured the Round Trip Delay (RTD) using RAW, UDP and TCP sockets to interface the protocol stack. We verified that on high computing power platforms the difference between the sockets is small but still significant in resource-constrained platforms. On the other hand, full featured general OSs present rather large worst-case delays. These can be reduced using real-time patches for those OSs, RTOSs, or even removing unnecessary modules, services and particularly, data intensive device drivers. We believe this study can be helpful for system designers as well as for teaching networks courses in embedded systems