Performance analysis of large-scale parallel-distributed processing with backup tasks for cloud computing

In cloud computing, a large-scale parallel-distributed processing service is provided where a huge task is split into a number of subtasks and those subtasks are processed on a cluster of machines called workers. In such a processing service, a worker which takes a long time for processing a subtask makes the response time long (the issue of stragglers). One of efficient methods to alleviate this issue is to execute the same subtask by another worker in preparation for the slow worker (backup tasks). In this paper, we consider the efficiency of backup tasks. We model the task-scheduling server as a single-server queue, in which the server consists of a number of workers. When a task enters the server, the task is split into subtasks, and each subtask is served by its own worker and an alternative distinct worker. In this processing, we explicitly derive task processing time distributions for the two cases that the subtask processing time of a worker obeys Weibull or Pareto distribution. We compare the mean response time and the total processing time under backup-task scheduling with those under normal scheduling. Numerical examples show that the efficiency of backup-task scheduling significantly depends on workers' processing time distribution

A novel plant nuclear gene encoding chloroplast ribosomal protein S9 has a transit peptide related to that of rice chloroplast ribosomal protein L12

AbstractWe have cloned a novel nuclear gene for a ribosomal protein of rice and Arabidopsis that is like the bacterial ribosomal protein S9. To determine the subcellular localization of the gene product, we fused the N-terminal region and green fluorescent protein and expressed it transiently in rice seedlings. Localized fluorescence was detectable only in chloroplasts, indicating that this nuclear gene encodes chloroplast ribosomal protein S9. The N-terminal region of rice ribosomal protein S9 was found to have a high sequence similarity to the transit peptide region of the rice chloroplast ribosomal protein L12, suggesting that these transit peptides have a common lineage

Neutron Activation Analysis of Thorium by the Use of the Japan Materials Testing Reactor

Hydraulic power rabbit in the Japan Materials Testing Reactor (JMTR) was used for highly sensitive neutron activation analysis of thorium in silica and aluminum. The thermal neutron flux of JMTR is higher than 1x10^n/cm^2/sec. A number of radioactive isotopes were made from impurities of high purity aluminum and silica irradiated in JMTR. ^Ta, which was produced from ^Ta by (2n, γ) reaction, was observed and made the determination of thorium difficult. The objective activation products ^Pa for the determination of thorium was isolated from majority of interfering radioactivity by a method combined with anion exchange and LaF_3 coprecipitation. It was found that the detection limit of thorium was less than 2x10^g. The method is useful to the analysis for thorium in high purity aluminum and silica that might be used to make very large scale integrated circuit

Abscess Formation of the Round Ligament of the Liver: Report of a Case

Abscess formation of the round ligament of the liver is very rare. We report a case of a 70-year-old female with abscess of the round ligament after an endoscopic papillotomy for choledocholithiasis. On the 21st day following papillotomy, abscess formation of the round ligament was found by ultrasonographic examination. Surgical treatment was performed because conservative therapy was not effective. The purulent fluid and necrotic tissue at the round ligament were completely removed. Cultures obtained from the abscess grew Staphylococcus epidermidis, but the mechanism of abscess formation in this case remains unclear.</p

Estimation of catch efficiency of a small seine for larval and juvenile Japanese sea bass, Lateolabrax japonicus, in the Ohta estuary

河口域における魚類群集の主要構成者であるスズキ仔稚魚に対する小型曳き網（幅2.3m，高さ1m）の採集効率を，地曳き網（幅16m，高さ1m）による採集結果と比較することにより推定した。2008年3月21日と4月7日に太田川放水路感潮域において合計15回の曳網を行い，合計1,502個体（標準体長14.5－24.0mm）のスズキ仔稚魚を採集した。地曳き網の網目からの逸出が生じる体長16mm未満と，個体密度が著しく低下する23mm以上については解析対象とせず，地曳き網による採集効率を100％と仮定した。体長1mmごとに区分した分布密度を採集具間で比較した結果，小型曳き網による体長16mm以上18mm未満のスズキ仔稚魚採集効率は約100％と推定された。体長18mm以上23mm未満では採集効率（C, ％）が体長（L, mm）に比例して直線的に減少した（C=－17.2*L+388.8，n=11，r2=0.77，p=0.0004）。In order to estimate catch efficiency of a small seine (1.0 by 2.3 m, 2 mm mesh aperture) for larval and juvenile Japanese sea bass Lateolabrax japonicus, results from experimental hauls of the small seine were compared with those from a large seines (1.0 by 16 m, 2.5 mm mesh aperture) in the Ohta Diversion Channel on March 21 and April 7, 2008. A total of 1,502 Japanese sea bass, ranging between 14.5 and 24.0 mm in standard length were collected. Data of fish <15.9 mm was excluded from the analysis since extrusion of these fish through the mesh of the large seine was possible. Comparison of the Japanese sea bass abundance at lengths between the small and large seines revealed that the catch efficiency of the small seine for Japanese sea bass <18.0 mm was approximately 100%. The catch efficiency decreased with the increase in fish body length between 18.0 and 22.9 mm. A linear model was fitted to the relationship between the catch efficiency (C, %) and body length (L, mm): C=－17.2*L+388.8 (n=11, r2=0.77, p=0.0004). Catch efficiency was not estimated for Japanese sea bass ＞ 23 mm since their abundance was quite low in the surveyed area probably due to migration to downriver or sea areas, which are considered as habitats for the following life stages

A quantitative comparison of fish assemblage between amacroalgae bed and an adjoining sandy beach in the central Seto Inland Sea

植生の有無が魚類群集に与える影響を明らかにすることを目的として，瀬戸内海中央部の無人島（小久野島）の東岸において隣接するガラモ場と砂浜の魚類相調査を実施した。ガラモ場と砂浜に10m四方（面積100m2）の調査区画を各4ヶ所設定し，季節に1回の頻度で（2006年8月，11月，2007年2月，5月）小型巻網（目合い4mm）を用いて区画内の魚類をすべて採集した。一年間の調査により，ガラモ場で20種以上1,397個体，砂浜で17種以上902個体の魚類が採集された。個体数にもとづく優占種（上位3種）は，ガラモ場ではシロメバル，ヒメハゼ，ハオコゼ，砂浜ではヒメハゼ，ボラ，スジハゼ，湿重量にもとづく優占種は，ガラモ場ではシロメバル，ハオコゼ，キュウセン，砂浜ではヒメハゼ，シロギス，ボラであった。100m2あたりの出現種数，個体密度，バイオマスはいずれもガラモ場において大きな季節変動を示した。8月にはガラモ場における種数が砂浜よりも有意に多かった。ガラモ場においては，ホンダワラ類の繁茂期である2－5月にシロメバル仔稚魚の来遊にともなう個体密度とバイオマスの急増が認められた。Biological and physical surveys were conducted at amacloalgae bed (MB) and a sandy beach (SB) off an inhabited island in the central Seto Inland Sea, Japan, from August 2006 tomay 2007 in order to detect the effect of vegetation on fish assemblage. Fish were collected using a seine net (2m in height, 3mm in mesh aperture) at four separate locations within MB and SB during a tidal level between 70-130 cm in daytime on 4 Aug. and 16 Nov. 2006 and 19 Feb. and 2 May 2007. A total of 1,397 and 902 fish were collected at MB and SB, respectively. The numerically dominant species were Sebastes cheni, Favonigobius gymnauchen and Hypodytes rubripinnis in MB and Favonigobius gymnauchen, mugil cephalus cephalus and Acentrogobius pflaumii in SB. Weight-based dominant species were Sebastes cheni, Hypodytes rubripinnis and Halichoeres poecilopterus in MB and Favonigobius gymnauchen, Sillago japonica and Mugil cephalus cephalus. Seasonal fluctuation in number of fish species, fish abundance and biomass in MB were larger than those in SB. The number of fish species in August in MB was significantly higher than that in SB. Fish abundance and biomass in MB abruptly increased fromFebruary to May due to immigration of S. cheni larvae and juveniles