Diversity of lactic acid bacteria from modified atmosphere packaged sliced cooked meat products at sell-by date assessed by PCR-denaturing gradient gel electrophoresis

The predominant lactic acid bacteria (LAB) microbiota associated with three types of modified atmosphere packaged (MAP) sliced cooked meat products (i.e. ham, turkey and chicken) was analyzed at sell-by date using a combination of culturing and molecular population fingerprinting. Likewise routine analyses during industrial MAP production, meat samples were plated on the general heterotrophic Plate Count Agar (PCA) and on the LAB-specific de Man, Rogosa, Sharpe (MRS) agar under different temperature and atmosphere conditions. Subsequently, community DNA extracts were prepared from culturable bacterial fractions harvested from both media and used for PCR targeting the V3 hyper-variable region of the 16S rRNA gene followed by denaturing gradient gel electrophoresis (DGGE) of PCR amplicons (PCR-DGGE). Irrespective of aerobic or anaerobic incubation conditions, V3-16S rDNA DGGE fingerprints of culturable fractions from PCA and MRS medium displayed a high level of similarity indicating that LAB constituted the most dominant group in the culturable bacterial community. Comparison of DGGE profiles of fractions grown at 20, 28 or 37 °C indicated that part of the culturable community consisted of psychrotrophs. Four DGGE bands were common among cooked ham, turkey and chicken products, suggesting that these represent the microbiota circulating in the plant where all three MAP product types were sliced and packaged. Based on band sequencing and band position analysis using LAB reference strains, these four bands could be assigned to Lactobacillus sakei and/or the closely related Lactobacillus fuchuensis, Lactobacillus curvatus, Carnobacterium divergens and Leuconostoc carnosum. In conclusion, the PCR-DGGE approach described in this study allows to discriminate, identify and monitor core and occasional LAB microbiota of MAP sliced cooked meat products and provides valuable complementary information to the current plating procedures routinely used in industrial plants.     

Clock trees: logical clocks for programs with nested parallelism

A vector clock is a valuable tool for maintaining run time concurrency information in parallel programs. A novel method is presented for modifying vector clocks to make them suitable for programs with nested fork join parallelism (having a variable number of tasks). The resulting kind of clock is called a clock tree, due to its tree structure. The clock tree method compares favorably with other timestamping methods for variable parallelism: task identifier reuse and task recycling. The worst case space requirements of clock trees equals the best case for the latter two methods, and the average size of a clock tree is much smaller than the size of a vector with task recycling. Furthermore, the algorithm for maintaining clock trees does not require a shared data structure and thus avoids the serialization bottleneck that task recycling suffers from     

Improving study habits of junior high school students through self-management versus group discussion.

Both a self-management approach, teaching the principles of behavior modification and self-control (n = 36), and a group discussion technique, involving discussion of study habits and problems (n = 41), led to improvements in GPAs compared with a no-treatment control group (n = 36) for low-achieving junior high school students. Ss in both treatment groups reported improvement in their academic abilities relative to those of other junior high school students after the program. More than those in the group discussion condition, those in the self-management group also reported that they were more likely to have a specific time and place to study and that the program had increased their efficiency and time spent studying. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transport properties of self compacting concrete with limestone filler or fly ash

The durability of a cementitious material is greatly influenced by the permeability of the material for potentially aggressive substances. As the pore structure of self compacting concrete (SCC) might be different in comparison with traditional concrete (TC), some changes in durability behaviour may occur. At this moment however, it is unclear how significant these differences will be with regard to the concrete practice. In this paper, the gas and water transport in SCC with limestone filler or fly ash is investigated experimentally. Nine different concrete compositions are considered: one TC and eight SCC mixtures. Some important parameters like the water/cement (W/C) and cement/powder ratio (C/P), type of filler (limestone filler and fly ash), type of aggregate and type of cement are considered. The results of the gas and water transport are discussed and linked to experimental data concerning pore volume. Lower transport properties can be obtained by using fly ash instead of limestone as filler material, by lowering the W/C ratio, decreasing the C/P ratio at a constant W/C ratio or using blast furnace slag cement instead of portland cement. The effect of changing from gravel to crushed limestone is small. SCC is differing strongly of TC with respect to the apparent gas permeability. This difference is probably due to the differences in pore volume, as seen from MIP results.     

Commercial Integrated Permeate Channel Ultrafiltration Membranes: Design,Modeling and Performance

Submerged ultrafiltration membranes for use in wastewater treatment have been practiced for several decades and is becoming the standard for water reuse applications. In this paper, the characteristics of the unique and robust Integrated Permeate Channel (IPC®) membrane are presented for membrane bioreactor (MBR) applications. The design choices made during the 10-year development of the IPC® membrane translate in key product attributes that the end users are looking for: a high capacity of clean permeate per footprint at the lowest cost of total ownership over the lifetime of the product.     

Empirical validation of a real options theory based method for optimizing evacuation decisions within chemical plants

This article empirically assesses and validates a methodology to make evacuation decisions in case of major fire accidents in chemical clusters. In this paper, a number of empirical results are presented, processed and discussed with respect to the implications and management of evacuation decisions in chemical companies. It has been shown in this article that in realistic industrial settings, suboptimal interventions may result in case the prospect to obtain additional information at later stages of the decision process is ignored. Empirical results also show that implications of interventions, as well as the required time and workforce to complete particular shutdown activities, may be very different from one company to another. Therefore, to be optimal from an economic viewpoint, it is essential that precautionary evacuation decisions are tailor-made per company.     

Performance assessment of electrospun nanofibers for filter applications

The aim of this study was to evaluate the use of nanofiber microfiltration membranes, spun by an innovative electrospinning technique, in water filtration applications. As such, this study bridges between developments in electrospinning techniques for the production of flat sheet membranes and the application of these membranes in water filtration. Three different applications were examined. First, the use of the membrane (functionalized or non-functionalized) for the removal of pathogens was investigated. Second the electrospun flat sheet membranes were applied in a lab scale submerged membrane bioreactor (MBR). Third, the electrospun membranes were applied as stand-alone filter for water treatment. Next to these applications, physical properties such as clean water permeability (CWP) and strength were also examined. The test showed that the electrospun membranes can be used for water filtration applications, but that further research is necessary towards irreversible fouling properties and level of functionalisation.     

Interrupt replay: a debugging method for parallel programs with interrupts

The behaviour of programs for multiprocessors may be indeterminate, due to processor timing variations. This poses a problem for cyclic debugging, since a bug may disappear from one execution to another. Replay is an elegant solution to this problem, in which ‘sufficient’ information is recorded in a log. This information is then used to control subsequent executions of the same program so that repeatability is guaranteed. Interrupts are another source of non-determinism, even in sequential programs. This paper presents an extension of the well-known Instant Replay method, termed Interrupt Replay, for replaying programs in the presence of interrupts. The correctness of Interrupt Replay is based on the assumption that there are no interrupt races: an interrupt service routine must not access data that is also accessed by the foreground process whenever the interrupt is enabled. If such races are present then replay may fail to produce deterministic results. This assumption is similar to the basic assumption of Instant Replay that shared variables are properly protected by mutual exclusion. Also as in Instant Replay, it is assumed that the behaviour of the environment (input data, external interrupts) is replayed by some other tracing mechanism.     

Towards a fundamental evaluation of water retention tests for curing compounds

The use of curing compounds on fresh concrete is well known to prevent moisture loss of the surface. When excessive moisture loss is not prevented, plastic shrinkage cracking is likely to occur and there will be a lack of water to hydrate the cement, resulting in a concrete with lower surface strengths and lower durability. On the occasion of CEN activities concerning curing compounds, a Belgian national working group was installed to study a new test method for curing compounds. The existing project standard developed by TG 11 of CEN TC 104/SC3 was examined and some minor modifications were made. A round robin test was carried out with the collaboration of 5 Belgian test laboratories. Eight curing compounds and water were tested. A linear relationship was found between the relative compressive strength at 28 days and the efficiency to evaporation at 7 days in a climate room. This relationship is explained by calculations based on the degree of hydration for which values were estimated based on the measured weight losses of the specimens.

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Résumé Afin de prévenir la dessiccation du béton frais, l'application d'un produit de cure est une mesure bien connue. En cas de perte d'eau trop excessive pendant le durcissement du béton, la fissuration à cause du retrait plastique est fort probable. Par conséquent, un manque d'eau peut aussi se produire, causant un arrêt précoce de l'hydratation, induisant une faible résistance et une durabilité limitée. à l'occasion des activités de la CEN concernant les produits de cure, un groupe de travail belge a été installé. La pré-norme actuelle, développée par TG 11 de CEN TC 104/SC3, a été examinée et quelques modifications ont été introduites. Les essais inter-laboratoires étaient réalisés avec la collaboration de 5 laboratoires belges, essayant huit produits de cure avec de l'eau. Un rapport linéaire entre la résistance relative à la compression à 28 jours et l'efficacité contre l'évaporation après 7 jours dans la salle climatisée, est obtenu. Ce rapport est évalué d'une manière fondamentale en faisant des calculs basés sur le degré d'hydratation.

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Editorial Note Prof. Dr. Geert De Schutter is a RILEM Senior Member. He participates in the work of RILEM TC 181-EAS (“Early age shrinkage induced stresses and cracking in cementitious systems’). He was also awarded the 2001 Robert L'Hemite Medal.