Performance Analysis of MapReduce with In-Memory Caching in HDFS

Department of Computer EngineeringIn this paper, we study the effects of HDFS in-memory caching on various MapReduce applications. We first evaluate the performance of seven MapReduce applications to understand different resource usage patterns. We then modify the centralized cache management system in HDFS such that individual blocks of a file can be cached. Using the modified system in HDFS, we compare the performance of MapReduce applications with in-memory caching to that without in-memory caching for workloads of a single MapReduce application and multiple MapReduce applications. In the experiments, the same workload was executed multiple times to see the effects of in-memory caching. Our experimental results show that the in-memory cache system can be beneficial to workloads of multiple I/O-intensive MapReduce applications, but the in-memory cache system cannot improve the performance of non-I/O- intensive MapReduce applications, possibly degrading the performance due to the overhead of in-memory caching.ope

The Author Response: Presence of Evolutionary Pressures or Genotyping Error

I would like to thank the interest and comments to our paper entitled “XRCC1 polymorphisms and risk of papillary thyroid carcinoma in a Korean sample ” (1). In our study, we genotyped XRCC1 Arg194Trp and Arg399Gln single nucleotide polymorphisms (SNPs) in 111 papillary thyroid carcinoma patients and 100 normal control subjects. In the results of our study, the XRCC1 Arg194Trp Arg/Trp genotype was significantly associated with a decreased risk of papillary thyroid carcinoma compared to that of Arg/Arg genotype, while the XRCC1 Arg399Gln genotype was not associated with a risk of papillary thyroid carcinoma. I agree with the comments. There was a mistake in the calculation of Hardy-Weinberg equilibrium (HWE). A genotype distribution of XRCC1 Arg194Trp was in HWE (control P = 0.728, case P = 0.768); however, a genotype distribution of XRCC1 Arg399Gln deviated from HWE (control P = 0.0002, case P

Seasonal variation of seaweed components and novel biological function of fucoidan extracted from brown algae in Quebec

Fucus vesiculosus et Ascophyllum nodosum sont des algues brunes comestibles et abondantes au Québec. Cependant, elles ont été négligées en raison de leur valeur potentielle inconnue et de la période de récolte limitée. Afin de valider leur utilité, la composition chimique de ces algues et l’activité inhibitrice des enzymes digestives de l'amidon par les fucoïdanes extraits de ces deux espèces d'algues ont été étudiés en fonction de la saison. Les composants principaux des algues sont dans l’ordre: les polysaccharides> minéraux> protéines> fucoïdane> lipides> > composés phénoliques, et leur quantité est très variable selon la période de récolte. F. vesiculosus contenait une plus grande quantité de protéines et de minéraux, alors que A. nodosum avait relativement plus de polysaccharides. Par conséquent, F. vesiculosus serait plus avantageux comme source d’éléments nutritifs. L’algue A. nodosum récoltée en Juillet a permis d’obtenir le fucoïdane ayant la pureté la plus élevée et le meilleur rendement. Les fucoïdanes extraits des deux espèces d’algues ont inhibé l’activité de l’α-glucosidase alors que seul celui extrait d’A. nodosum a pu, de plus, inhiber l’α-amylase. Le fucoïdane d’A. nodosum était un inhibiteur plus puissant que le fucoïdane de F. vesiculosus pour l’α-glucosidase avec des IC50 variant de 0,013 ~ 0,047 mg/ml, tout comme pour l’α-amylase avec des IC50 de 0,12 ~ 4,62 mg/mL selon le mois. Pour comprendre les facteurs clés expliquant les différences d’inhibition d’α-amylase entre les fucoïdane d’A. nodosum et F. vesiculosus, certaines caractéristiques structurales ont été analysées et comparées à du galactofucoidane qui a servi de contrôle. A partir des résultats obtenus, il est confirmé que la masse moléculaire plus faible (637 kDa) du fucoïdane d’A. nodosum et la présence de sulfates sont liées à son activité inhibitrice. Nous avons émis l’hypothèse que les faibles masses moléculaires permettent d’exposer facilement les groupements sulfate qui peuvent agir sur l’α-amylase par interaction électrostatique, et donc d'inhiber son activité. En conclusion, les algues brunes du Québec présentent un potentiel d’utilisation important pour leur valeur nutritionnelle et leurs composés bioactifs. Le fucoïdane a montré une activité d'inhibition des enzymes digestives de l'amidon (α-amylase et α-glucosidase) et cette activité est différente selon les espèces d'algues et la période de récolte. Une meilleure compréhension du mécanisme inhibiteur par le fucoïdane peut être utile afin de développer un ingrédient fonctionnel permettant de prévenir le diabète de Type-2.Fucus vesiculosus and Ascophyllum nodosum are edible brown seaweed and abundantly available in Quebec. However, they have been neglected because of their unknown value and technical limitation in harvest. In order to validate their usefulness, chemical composition in seaweeds and starch digestive enzyme inhibition activity by fucoidan extracted from two seaweed species were investigated with different seasons. The major components in both seaweeds were in order: polysaccharide > minerals > protein > fucoidan > lipid > phenol, and their quantity was quite variable depending on harvesting timing. F. vesiculosus contained larger amount of proteins and minerals, while A. nodosum had relatively more polysaccharides. Therefore, F. vesiculosus are advantageous as a nutritional source. Especially, from A. nodosum harvested in July, a fucoidan having higher purity and better yield was obtained. Fucoidans from two seaweeds species inhibited α-glucosidase activity while, only fucoidan from A. nodosum could inhibit α-amylase activity. A. nodosum fucoidan was a more potent inhibitor than F. vesiculosus fucoidan for α-glucosidase with IC50 of 0.013 ~ 0.047 mg/mL, and for α-amylase with IC50 of 0.12 ~ 4.62 mg/mL depending on harvest month. To understand the key factors explaining the difference in α-amylase inhibition between A. nodosum fucoidan and F. vesiculosus fucoidan, structural characteristic was analyzed and compared with galactofucoidan as a control. From the obtained results, it is confirmed that smaller molecular weight (637 kDa) of A. nodosum fucoidan and the presence of sulfates are related to its inhibitory activity. It is proposed that small molecular weight permits to expose easily sulfate groups for interaction with α-amylase throughout electrostatic interactions, and therefore inhibiting its activity. In conclusion, brown seaweeds in Quebec have a considerable importance for nutrition and bioactive products. Fucoidan shows the inhibition activity for starch digestive enzymes (α-amylase and α-glucosidase) and its activity is different depending on seaweed species and harvesting period. Further understanding of the inhibitory mechanism by fucoidan can be useful to develop a functional ingredient to help preventing for Type-2 diabetes

Knowledge and Technology Transfer: Levels and Key Factors

Most current literature on knowledge and technology transfer (Appropriability Model, Dissemination Model, and Knowledge Utilization Model), describe the process of transfer in details, but has limitation in terms of their application in contemporary high-tech industries since most studies have not provided plausible explanation on levels and factors affecting transfer of knowledge and/or technology. To overcome these limitations, the four levels of knowledge and technology transfer are suggested: Knowledge and Technology Creation (Level I), Sharing (Level II), Implementation (Level III), and Commercialization (Level IV). Comprehensive literature identifies sixteen variables affecting the process and results of knowledge and tec hnology transfer. The survey results show four key factors in knowledge and technology transfer: Communication, Distance, Equivocality, and Motivation. Communication refers to the degree to which a medium is able to efficiently and accurately conveys task-relevant information and media while distance involves both physical and cultural proximity. Equivocality refers to the degree of concreteness of knowledge and technology to be transferred while motivation involves incentives for and the recognition of the importance of knowledge and technology transfer activities. Further analysis shows that there are four distinctive clusters and they show very contrasting characteristics in terms of four key factors. The careful mapping of the four clusters on the four key factors show very informative knowledge and technology transfer patterns, the Knowledge and Technology Transfer Grid. Finally, actions to increase communication interactivity and motivation, and to reduce cultural distance and equivocality are suggested. Presented at the 4th International Conference on Technology Policy and Innovation (ICTPI) in Curitiba, Brazil.IC2 Institut

Adjacent Infrared Multitarget Detection Using Robust Background Estimation

Small target detection is very important for infrared search and track (IRST) problems. Grouped targets are difficult to detect using the conventional constant false alarm rate (CFAR) detection method. In this study, a novel multitarget detection method was developed to identify adjacent or closely spaced small infrared targets. The neighboring targets decrease the signal-to-clutter ratio in hysteresis threshold-based constant false alarm rate (H-CFAR) detection, which leads to poor detection performance in cluttered environments. The proposed adjacent target rejection-based robust background estimation can reduce the effects of the neighboring targets and enhance the small multitarget detection performance in infrared images by increasing the signal-to-clutter ratio. The experimental results of the synthetic and real adjacent target sequences showed that the proposed method produces an upgraded detection rate with the same false alarm rate compared to the recent target detection methods (H-CFAR, Top-hat, and TDLMS).111Ysciescopu

Clustering of Nodes in Layered-Tree Topology for Wireless Sensor Networks

Wireless sensor network is composed of a large number of sensor nodes of limited energy resource. The node clustering approach can improve the scalability and lifetime of wireless sensor network. In this paper we propose a novel node clustering protocol based on layered-tree topology for self-organizing distributed wireless sensor networks. It decides optimal number of clusters by employing a new approach for setting threshold value, including the probability of optimum number of cluster-heads and residual energy of the nodes. We also introduce a new scheme for layered-tree construction in each cluster. As a result, the proposed scheme can significantly improve the energy efficiency of the network and increase its lifetime. Computer simulation shows that the proposed scheme effectively reduces and balances the energy consumption of the nodes, and thus significantly extends the network lifetime compared to the existing schemes