A low latency optical top of rack switch for data centre networks with minimized processor energy load

We propose a low latency optical data center top of rack switch using recirculation buffering and a hybrid MZ/SOA switch architecture to reduce the network power dissipated on future optically connected server chips by 53%. © OSA 2014.

高速缓存优化的并行连接算法

由于嵌套循环连接操作过程中存在较大的高速缓存缺失,严重影响了连接查询的性能。提出了一种基于缓冲的高速缓存参数无关的嵌套循环并行连接算法。通过高速缓存参数无关和缓冲技术,提高了连接算法的空间局部性和时间局部性。理论分析和实验结果表明,高速缓存优化后的串行连接算法的性能是原来的2倍,其并行算法效果近似线性加速比。

Transfer and transport of phosphorus and silica in the turbidity maximum zone of the Changjiang estuary

The concentration of suspended particulate matter (SPM), sedimentation flux, and various forms of phosphorus and silica in turbidity maximum zone (TMZ) in the Changjiang (Yangtze) estuary was studied. Based on the budget of P and Si, their mass balances in the TMZ were calculated. Results show that the variation in concentration of dissolved inorganic silicon (DISi) was mainly controlled by seawater dilution, while that of dissolved inorganic phosphor-us (DIP) was considerably affected by the buffering of suspended matter and sediment. Our experiments showed that the sedimentation fluxes of SPM and particulate inorganic phosphorus (PIP), total particulate phosphorus (TPP), particulate inorganic silicon (PISi), and biological silicon (BSi) in the TMZ were 238.4 g m(-2) d(-1) and 28.3, 43.1, 79.0, 63.0 mg m(-2) d(-1), respectively. In addition, a simple method to estimate the ratio of resuspension of sediment in the TMZ was established, with which the rate in surface and bottom waters of the TMZ accounted for 55.7 and 66.1% of the total SPM, respectively, indicating that the sediment resuspension in the TMZ influenced significantly the mass balances of P and Si. Particulate adsorbed P (60.8%) and 35.5% of total particulate P discharged from the river were filtered and then deposited in the TMZ. The input flux of PIP from the river mouth was 55.9% of that of DIP, being important as biologically available P, while that of PISi was only 3.5% of DISi, showing that particulate adsorbed Si was much less important than particulate adsorbed P. (c) 2008 Elsevier Ltd. All rights reserved.

滚石机理及滚石灾害评价研究

Rockfall is a geological evolution process involving detachment of blocks or boulders from a slope face, then their free falls, bouncing, rolling or sliding, and finally deposition near the toe of the slope. Many facts indicate that the rockfall can cause hazards to peoples, and it can be regarded as a geological hazard. A rockfall event may only involve a boulder or rock, and also several ones. When there are peoples, buildings, or other man-made establishments within the scope of rockfall trajectory, losses will be possibly induced in tenns of human lives or damages to these facilities. Researches into mechanism, kinematics, dynamics, hazard assessment, risk analysis, and mitigation measures of rockfalls are extremely necessary and important. Occurrence of rockfall is controlled by a lot of conditions, mainly including topographical, geomorphic, geological ones and triggering factors. The rockfall especially in mountainous areas, has different origins, and occurs to be frequent, unexpected, uncertain, in groups, periodic and sectional. The characterization and classification of the rockfalls not only increase knowledge about rockfall mechanism, but also can instruct mitigation of the hazards. In addition, stability of potential rockfalls have various sensitivity to different triggering factors and changes of geometrical conditions. Through theoretical analyses, laboratory experiments and field tests, the author presents some back-analysis methods for friction coefficients of sliding and rolling, and restitution coefficients. The used input data can be obtained economically and accurately in the field. Through deep studies on hazard assessment methods and analysis of factors influencing rockfall hazard, this paper presents a new assessment methodology consisting of preliminary assessment and detailed one. From the application in a 430 km long stretch of the Highway, which is located between Paksho and Nyingtri in Tibet, the methodology can be applicable for the rockfall hazard assessment in complex and difficult terrains. In addition, risk analyses along the stretch are conducted by computing the probability of encountering rockfalls and life losses resulting from rockfall impacts. Rockfall hazards may be mitigated by avoiding hazardous areas, clearness of dangerous rocks, reinforcement, obstructing the rockfalls, leading the rockfalls, warning and monitoring for rockfalls, etc. Seen from present remedial level of rockfall hazards, different mitigation measures, economical and effective buffering units, monitoring tecliniques and consciousness of environmental protection for rockfall mitigations should be further developed.

Reliable Interconnection Networks for Parallel Computers

This technical report describes a new protocol, the Unique Token Protocol, for reliable message communication. This protocol eliminates the need for end-to-end acknowledgments and minimizes the communication effort when no dynamic errors occur. Various properties of end-to-end protocols are presented. The unique token protocol solves the associated problems. It eliminates source buffering by maintaining in the network at least two copies of a message. A token is used to decide if a message was delivered to the destination exactly once. This technical report also presents a possible implementation of the protocol in a worm-hole routed, 3-D mesh network.

Using Warp to Control Network Contention in Mermera

Parallel computing on a network of workstations can saturate the communication network, leading to excessive message delays and consequently poor application performance. We examine empirically the consequences of integrating a flow control protocol, called Warp control [Par93], into Mermera, a software shared memory system that supports parallel computing on distributed systems [HS93]. For an asynchronous iterative program that solves a system of linear equations, our measurements show that Warp succeeds in stabilizing the network's behavior even under high levels of contention. As a result, the application achieves a higher effective communication throughput, and a reduced completion time. In some cases, however, Warp control does not achieve the performance attainable by fixed size buffering when using a statically optimal buffer size. Our use of Warp to regulate the allocation of network bandwidth emphasizes the possibility for integrating it with the allocation of other resources, such as CPU cycles and disk bandwidth, so as to optimize overall system throughput, and enable fully-shared execution of parallel programs.

dPAM: A Distributed Prefetching Protocol for Scalable Asynchronous Multicast in P2P Systems

We leverage the buffering capabilities of end-systems to achieve scalable, asynchronous delivery of streams in a peer-to-peer environment. Unlike existing cache-and-relay schemes, we propose a distributed prefetching protocol where peers prefetch and store portions of the streaming media ahead of their playout time, thus not only turning themselves to possible sources for other peers but their prefetched data can allow them to overcome the departure of their source-peer. This stands in sharp contrast to existing cache-and-relay schemes where the departure of the source-peer forces its peer children to go the original server, thus disrupting their service and increasing server and network load. Through mathematical analysis and simulations, we show the effectiveness of maintaining such asynchronous multicasts from several source-peers to other children peers, and the efficacy of prefetching in the face of peer departures. We confirm the scalability of our dPAM protocol as it is shown to significantly reduce server load.

GreedyDual-Join: Locality-Aware Buffer Management for Approximate Join Processing Over Data Streams

We investigate adaptive buffer management techniques for approximate evaluation of sliding window joins over multiple data streams. In many applications, data stream processing systems have limited memory or have to deal with very high speed data streams. In both cases, computing the exact results of joins between these streams may not be feasible, mainly because the buffers used to compute the joins contain much smaller number of tuples than the tuples contained in the sliding windows. Therefore, a stream buffer management policy is needed in that case. We show that the buffer replacement policy is an important determinant of the quality of the produced results. To that end, we propose GreedyDual-Join (GDJ) an adaptive and locality-aware buffering technique for managing these buffers. GDJ exploits the temporal correlations (at both long and short time scales), which we found to be prevalent in many real data streams. We note that our algorithm is readily applicable to multiple data streams and multiple joins and requires almost no additional system resources. We report results of an experimental study using both synthetic and real-world data sets. Our results demonstrate the superiority and flexibility of our approach when contrasted to other recently proposed techniques.

Fundamental studies of sourdoughs fermented with Weissella cibaria and Lactobacillus plantarum: influence on baking characteristics, sensory profiles and in vitro starch digestibility of gluten-free breads

The application of sourdough can improve texture, structure, nutritional value, staling rate and shelf life of wheat and gluten-free breads. These quality improvements are associated with the formation of organic acids, exopolysaccharides (EPS), aroma or antifungal compounds. Initially, the suitability of two lactic acid bacteria strains to serve as sourdough starters for buckwheat, oat, quinoa, sorghum and flours was investigated. Wheat flour was chosen as a reference. The obligate heterofermentative lactic acid bacterium (LAB) Weissella cibaria MG1 (Wc) formed the EPS dextran (a α-1,6-glucan) from sucrose in situ with a molecular size of 106 to 107 kDa. EPS formation in all breads was analysed using size exclusion chromatography and highest amounts were formed in buckwheat (4 g/ kg) and quinoa sourdough (3 g/ kg). The facultative heterofermentative Lactobacillus plantarum FST1.7 (Lp) was identified as strong acidifier and was chosen due to its ubiquitous presence in gluten-free as well as wheat sourdoughs (Vogelmann et al. 2009). Both Wc and Lp, showed highest total titratable acids in buckwheat (16.8 ml; 26.0 ml), teff (16.2 ml; 24.5 ml) and quinoa sourdoughs (26.4 ml; 35.3 ml) correlating with higher amounts of fermentable sugars and higher buffering capacities. Sourdough incorporation reduced the crumb hardness after five days of storage in buckwheat (Wc -111%), teff (Wc -39%) and wheat (Wc -206%; Lp -118%) sourdough breads. The rate of staling (N/ day) was reduced in buckwheat (Ctrl 8 N; Wc 3 N; Lp 6 N), teff (Ctrl 13 N; Wc 9 N; Lp 10 N) and wheat (Ctrl 5 N; Wc 1 N; Lp 2 N) sourdough breads. Bread dough softening upon Wc and Lp sourdough incorporation accounted for increased crumb porosity in buckwheat (+10.4%; +4.7), teff (+8.1%; +8.3%) and wheat sourdough breads (+8.7%; +6.4%). Weissella cibaria MG1 sourdough improved the aroma quality of wheat bread but had no impact on aroma of gluten-free breads. Microbial shelf life however, was not prolonged in any of the breads regardless of the starter culture used. Due to the high prevalence of insulin-dependent diabetes mellitus particular amongst coeliac patients, glycaemic control is of great (Berti et al. 2004). The in vitro starch digestibility of gluten-free breads with and without sourdough addition was analysed to predict the GI (pGI). Sourdough can decrease starch hydrolysis in vitro, due to formation of resistant starch and organic acids. Predicted GI of gluten-free control breads were significantly lower than for the reference white wheat bread (GI=100). Starch granule size was investigated with scanning electron microscopy and was significantly smaller in quinoa flour (<2 μm). This resulted in higher enzymatic susceptibility and hence higher pGI for quinoa bread (95). Lowest hydrolysis indexes for sorghum and teff control breads (72 and 74, respectively) correlate with higher gelatinisation peak temperatures (69°C and 71°C, respectively). Levels of resistant starch were not increased by addition of Weissella cibaria MG1 (weak acidifier) or Lactobacillus plantarum FST1.7 (strong acidifier). The pGI was significantly decreased for both wheat sourdough breads (Wc 85; Lp 76). Lactic acid can promote starch interactions with gluten hence decreasing starch susceptibility (Östman et al. 2002). For most gluten-free breads, the pGI was increased upon sourdough addition. Only sorghum and teff Lp sourdough breads (69 and 68, respectively) had significantly decreased pGI. Results suggest that the increase of starch hydrolysis in gluten-free breads was related to mechanism other than presence of organic acids and formation of resistant starch.

Health in the medieval world: Regionality and the bioarchaeology of Ireland and Britain

This study assesses regional health patterns in early medieval Ireland and Britain by analysing and interpreting palaeopathological indicators of stress. This was achieved by incorporating the results of demographic and palaeopathological study into the specific historical contexts. Although relatively small islands, both are home to unique and diverse cultural, physical, and political landscapes, which could potentially affect the general health of the population in different ways. To accurately answer the research question, a bioarchaeological survey of six regions within both islands was carried out, specifically analysing and comparing the demographic profile and general health trends within each region with one another. Results from the analysis have demonstrated statistically significant differences within and between the islands. Inferring that even the more subtle differences observed within the cultural, physical, and political landscapes, such as in the case of Ireland and Britain, can and do affect general health trends. The health of early medieval Ireland and Britain appears to be significantly affected by the physical landscape, specifically a north/south divide. The most northerly regions, Scotland South and Ireland North, manifested higher levels of stress indicators when compared to the more southerly positioned regions. Although it can only be hypothesised what factors within these regions are causing, enhancing or buffering stress, the study has established the potential and necessity for regional work to be continued when interpreting the historical past of these two islands.

Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers.

Carbon Capture and Storage may use deep saline aquifers for CO(2) sequestration, but small CO(2) leakage could pose a risk to overlying fresh groundwater. We performed laboratory incubations of CO(2) infiltration under oxidizing conditions for >300 days on samples from four freshwater aquifers to 1) understand how CO(2) leakage affects freshwater quality; 2) develop selection criteria for deep sequestration sites based on inorganic metal contamination caused by CO(2) leaks to shallow aquifers; and 3) identify geochemical signatures for early detection criteria. After exposure to CO(2), water pH declines of 1-2 units were apparent in all aquifer samples. CO(2) caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples. Solid-phase metal mobility, carbonate buffering capacity, and redox state in the shallow overlying aquifers influence the impact of CO(2) leakage and should be considered when selecting deep geosequestration sites. Manganese, iron, calcium, and pH could be used as geochemical markers of a CO(2) leak, as their concentrations increase within 2 weeks of exposure to CO(2).

Biological and ecological mechanisms supporting marine self-governance: The Seri Callo de Hacha Fishery in Mexico

My goal was to describe how biological and ecological factors give shape to fishing practices that can contribute to the successful self-governance of a small-scale fishing system in the Gulf of California, Mexico. The analysis was based on a comparison of the main ecological and biological indicators that fishers claim to use to govern their day-to-day decision making about fishing and data collected in situ. I found that certain indicators allow fishers to learn about differences and characteristics of the resource system and its units. Fishers use such information to guide their day-to-day fishing decisions. More importantly, these decisions appear unable to shape the reproductive viability of the fishery because no indicators were correlated to the reproductive cycle of the target species. As a result, the fishing practices constitute a number of mechanisms that might provide short-term buffering capacity against perturbations or stress factors that otherwise would threaten the overall sustainability and self-governance of the system. The particular biological circumstances that shape the harvesting practices might also act as a precursor of self-governance because they provide fishers with enough incentives to meet the costs of organizing the necessary rule structure that underlies a successful self-governance system.

Convergent differential regulation of parvalbumin in the brains of vocal learners.

Spoken language and learned song are complex communication behaviors found in only a few species, including humans and three groups of distantly related birds--songbirds, parrots, and hummingbirds. Despite their large phylogenetic distances, these vocal learners show convergent behaviors and associated brain pathways for vocal communication. However, it is not clear whether this behavioral and anatomical convergence is associated with molecular convergence. Here we used oligo microarrays to screen for genes differentially regulated in brain nuclei necessary for producing learned vocalizations relative to adjacent brain areas that control other behaviors in avian vocal learners versus vocal non-learners. A top candidate gene in our screen was a calcium-binding protein, parvalbumin (PV). In situ hybridization verification revealed that PV was expressed significantly higher throughout the song motor pathway, including brainstem vocal motor neurons relative to the surrounding brain regions of all distantly related avian vocal learners. This differential expression was specific to PV and vocal learners, as it was not found in avian vocal non-learners nor for control genes in learners and non-learners. Similar to the vocal learning birds, higher PV up-regulation was found in the brainstem tongue motor neurons used for speech production in humans relative to a non-human primate, macaques. These results suggest repeated convergent evolution of differential PV up-regulation in the brains of vocal learners separated by more than 65-300 million years from a common ancestor and that the specialized behaviors of learned song and speech may require extra calcium buffering and signaling.

A whole-cell and single-channel study of the voltage-dependent outward potassium current in avian hepatocytes.

Voltage-dependent membrane currents were studied in dissociated hepatocytes from chick, using the patch-clamp technique. All cells had voltage-dependent outward K+ currents; in 10% of the cells, a fast, transient, tetrodotoxin-sensitive Na+ current was identified. None of the cells had voltage-dependent inward Ca2+ currents. The K+ current activated at a membrane potential of about -10 mV, had a sigmoidal time course, and did not inactivate in 500 ms. The maximum outward conductance was 6.6 +/- 2.4 nS in 18 cells. The reversal potential, estimated from tail current measurements, shifted by 50 mV per 10-fold increase in the external K+ concentration. The current traces were fitted by n2 kinetics with voltage-dependent time constants. Omitting Ca2+ from the external bath or buffering the internal Ca2+ with EGTA did not alter the outward current, which shows that Ca2+-activated K+ currents were not present. 1-5 mM 4-aminopyridine, 0.5-2 mM BaCl2, and 0.1-1 mM CdCl2 reversibly inhibited the current. The block caused by Ba was voltage dependent. Single-channel currents were recorded in cell-attached and outside-out patches. The mean unitary conductance was 7 pS, and the channels displayed bursting kinetics. Thus, avian hepatocytes have a single type of K+ channel belonging to the delayed rectifier class of K+ channels.

Polyacid-modified composite resins ("compomers") and their use in clinical dentistry

OBJECTIVES: This paper describes the chemistry and properties of polyacid-modified composite resins ("compomers") designed for use in clinical dentistry, and reviews the literature in this area. METHODS: Information has been obtained from over 50 published articles appearing in the dental and biomaterials literature, with studies being principally identified through MedLine. RESULTS: Published work shows that polyacid-modified composite resins constitute a discrete class of polymeric repair material for use in dentistry. Their distinction is that they contain hydrophilic components, and these cause water to be drawn into the material following cure. This triggers an acid-base reaction, and gives the materials certain clinically-desirable properties (fluoride release, buffering capability) that are also associated with glass-ionomer cements. The water uptake leads to a decline in certain, though not all, physical properties. However, clinical studies have shown these materials to perform acceptably in a variety of applications (Class I, Class II and Class V cavities, as fissure sealants and as orthodontic band cements), especially in children's teeth. CONCLUSIONS/SIGNIFICANCE: Polyacid-modified composite resins constitute a versatile class of dental repair material, whose bioactivity confers clinical advantages, and which are particularly useful in children's dentistry.