Replay-based debugging of occam programs

Parallel programs are intrinsically non-deterministic, and therefore the techniques of cyclical debugging that are commonly used for sequential programs are not suitable for parallel ones. This paper proposes a method to reproduce Occam program behaviour. Saving information on the timer values input by the program and the guards selected at run-time on alternative commands allows program replay, i.e. it makes it possible to re-execute the program deterministically with the same inputs following the same instruction path. This enables the software developer to use tools such as debuggers and intrusive monitors to help identify program faults. After discussing possible implementations of the proposed technique, IRD (an interactive replay debugger for Occam programs) is described. Finally, the use of the IRD in a sample debug session is presented as an example.     

Elevated superoxide dismutase in black alcoholics

Superoxide dismutase concentrations in lysates of erythrocytes from black alcoholics were higher than those of white alcoholics and of nonalcoholics of both races. Higher concentrations of enzyme protein, as determined by competition radioimmunoassay, correspond to proportionately higher enzyme activity. Elevated superoxide dismutase levels were not related to any other clinical, historical, or demographic variables. Increased superoxide dismutase levels may delay or prevent some of the pathological sequelae of alcoholism and may be a useful biological marker for alcohol abuse.     

Measuring efficiency of Vietnamese public colleges: an application of the DEA‐based dynamic network approach

In Vietnam, public colleges play a crucial role in shaping the socioeconomic and educational development strategies and providing a skilled labor force needed for the country's market‐oriented economy. Using balanced panel data for 2011–2013, we use the integrated data envelopment analysis based dynamic network model to examine dynamic changes in efficiencies of public colleges in the education sector. This model allows simultaneously estimating efficiencies of financial and academic operations and the overall dynamic changes of colleges in a network structure. Our findings indicate that the overall efficiencies of colleges are, on average, 0.741 while the average efficiencies of the financial and academic operations are 0.722 and 0.760, respectively. Furthermore, the in‐city colleges are more efficient than others, 0.776 and 0.728, respectively.     

An SLA-based Broker for Cloud Infrastructures

The breakthrough of Cloud comes from its service oriented perspective where everything, including the infrastructure, is provided “as a service”. This model is really attractive and convenient for both providers and consumers, as a consequence the Cloud paradigm is quickly growing and widely spreading, also in non commercial contexts. In such a scenario, we propose to incorporate some elements of volunteer computing into the Cloud paradigm through the Cloud@Home solution, involving into the mix nodes and devices provided by potentially any owners or administrators, disclosing high computational resources to contributors and also allowing to maximize their utilization. This paper presents and discusses the first step towards Cloud@Home: providing quality of service and service level agreement facilities on top of unreliable, intermittent Cloud providers. Some of the main issues and challenges of Cloud@Home, such as the monitoring, management and brokering of resources according to service level requirements are addressed through the design of a framework core architecture. All the tasks committed to the architecture’s modules and components, as well as the most relevant component interactions, are identified and discussed from both the structural and the behavioural viewpoints. Some encouraging experiments on an early implementation prototype deployed in a real testing environment are also documented in the paper.     

PDLC based on unsaturated polyester resins: molecular, morphological and thermo-optical analysis

A thermosetting matrix based on an unsaturated polyester resin was employed to realise a Polymer Dispersed Liquid Crystal (PDLC) system by a UV induced curing process. A molecular, morphological and thermo-optical characterisation of this system is presented. The chemical and structural properties were investigated by transmission FT-IR spectra in the near infrared frequency range and by dynamic-mechanical analysis. The results indicated that, upon curing, the matrix retains its intrinsic properties even for compositions very rich in the LC component (40 wt %). The morphology, investigated by optical and electron microscopy, showed phase separation before and after the curing process. Image analysis demonstrated that the cured materials had morphological features suitable to achieve interesting thermo-optical properties. In particular, the composition containing 40 wt % of LC exhibited the typical behaviour of a thermo-optical switch. Interesting optical bistability effects were also demonstrated for this particular composition.     

An investigation into the kinetic hydrate inhibitor properties of two imidazolium-based ionic liquids on Structure II gas hydrate

Kinetic hydrate inhibitors (KHIs) are used to prevent gas hydrate formation in gas and oilfield operations. All KHIs discovered to date are water-soluble polymers. However, their performance can be enhanced by certain non-polymeric organic molecules. Recently, it was claimed that certain imidazolium-based ionic liquids could have a dual function, acting as both thermodynamic inhibitors and KHIs (Xiao, C., Adidharma, H., 2009. Chem. Eng. Sci. 64, 1522). As the KHI experimental work was carried out at a temperature of –12 °C, giving a very high subcooling of about 25 °C, we reinvestigated two of these ionic liquids at more typical subsea temperatures and subcoolings. We find that these ionic liquids are very poor KHIs when used alone at 5000–10000 ppm, but they are fairly good synergists for commercial KHIs based on vinyl lactam polymers and hyperbranched poly(ester amide)s. Both ionic liquids showed only weak growth inhibition of tetrahydrofuran hydrate crystals. Finally, both ionic liquids were poorly biodegraded in the OECD306 seawater 28 day biodegradation test.     

Tetrahydrofuran hydrate crystal growth inhibition by hyperbranched poly(ester amide)s

Kinetic hydrate inhibitors (KHIs) are water-soluble polymers designed to delay gas hydrate formation in gas and oilfield operations. Inhibition of growth of gas hydrate crystals is one of the mechanisms by which KHIs have been proposed to act. One class of commercial KHIs is the hyperbranched poly(ester amide)s. We have investigated the ability of a range of structurally different hyperbranched poly(ester amide)s to inhibit the crystal growth of tetrahydrofuran (THF) hydrate which forms a Structure II clathrate hydrate, the most common gas hydrate structure encountered in the upstream oil and gas industry. The results indicate that there is an optimum size of hydrophobic groups attached to the succinyl part of the polymer, which gives best crystal growth inhibition. However, total inhibition was impossible to achieve even at a concentration of 8000 ppm of one of the best polymers at a subcooling of 3.4 °C, tentatively suggesting that polymer adsorption onto natural gas hydrate crystal surfaces is probably not the primary mechanism of kinetic inhibition operating in field applications with this class of KHI.     

The monitoring of inter-process communications in distributed systems

The decomposition of an application into processes and the allocation of the latter to the available processors is one of the most crucial problems in the software design phase of message-based distributed systems. In this paper the authors describe a tool which, by monitoring the communications between processes allocated to separate processing elements, is able to provide indications on the effectiveness of the partitioning and mapping actions carried out. The authors first show, with reference to systems built with Transputer family components, the tool's structure, which is highly independent from the system interconnection network; secondly, they show how to make an initial reduction of the data gathered during the monitoring phase.     

Efficiency measurements of deuterated liquid scintillators using d(d,n)He coincidence events

Deuterated liquid scintillators are promising from the perspective of n/γ separation and neutron energy measurement without time-of-flight. In order to turn these into precision instruments for nuclear physics, however, the absolute efficiency must be known. The efficiency is typically a function of energy and is strongly dependent on the electronics thresholds used with the photomultiplier detectors. This study involves the extraction of this efficiency using the d(d,n)³He reaction (E_d=16.0 MeV) and n-³He coincidence events. The detection and identification of the ions are very efficient and allows one to project pure monoenergetic neutron spectra all the way down to the electronics threshold. Timing information was also recorded in these measurements to provide further constraints and a consistency check.     

Exploiting olive oil mill effluents as a renewable resource for production of biodegradable polymers through a combined anaerobic–aerobic process

BACKGROUND: The performance of a three‐stage process for polyhydroxyalkanoate (PHA) bioproduction from olive oil mill effluents (OME) has been investigated. In the first anaerobic stage OME were fermented in a packed bed biofilm reactor into volatile fatty acids (VFAs). This VFA‐rich effluent was fed to the second stage, operated in an aerobic sequencing batch reactor (SBR), to enrich mixed cultures able to store PHAs. Finally, the storage response of the selected consortia was exploited in the third aerobic stage, operated in batch conditions. RESULTS: The anaerobic stage increased the VFA percentage in the OME from 18% to ～32% of the overall chemical oxygen demand (COD). A biomass with high storage response was successfully enriched in the SBR fed with the fermented OME at an organic load rate of 8.5 gCOD L^?1 d^?1, with maximum storage rate and yield (146 mgCOD gCOD^?1 h^?1 and 0.36 COD COD^?1, respectively) very similar to those obtained with a synthetic VFA mixture. By means of denaturing gradient gel electrophoresis (DGGE) analysis, different bacterial strains were identified during the two SBR runs: Lampropedia hyalina and Candidatus Meganema perideroedes, with the synthetic feed or the fermented OMEs, respectively. In the third stage, operated at increasing loads, the maximum concentration of the PHA produced increased linearly with the substrate fed. Moreover, about half of the stored PHAs were produced from substrates other than VFAs, mostly alcohols. CONCLUSION: The results obtained indicate that the process is effective for simultaneous treatment of OME and their valorization as a renewable resource for PHA production. Copyright © 2009 Society of Chemical Industry