Décodage par répliques

The very redundancy of a message enables to recover each symbol in terms of several partial contexts; in other words, it is possible to compute several replicas of each symbol in terms of other ones. Decoding of redundant codes is interpreted according to this viewpoint. A convenient formalism results in the statement of the maximum-likelihood decision rule on a symbol, given a set of its replicas, in the binary case. It is first applied to linear block codes. The decision rule which takes into account all possible replicas is expressed in terms of an exhaustive set of replicas, derived from the parity check matrix of the code. A modification of the decision rule, which saves its general shape, makes its result coincide with that of word-by-word maximum-likelihood decoding; besides, it simplifies this decision rule. Restricting the set of replicas taken into account also affords simplification of decoding, at the expense of optimality. It results in threshold decoding for orthogonalisable codes. The case of convolutional codes is more briefly discussed. The main specific problems are then the restriction to a finite context and the extension of the decision rule to non-systematic codes.     

Temperature effect on Listeria monocytogenes growth in the event of contamination of cooked pork products

The aim of this study was to describe the effect of temperature on the growth of Listeria monocytogenes in the event of postprocess contamination of packaged pork meats. This study was carried out in two steps. In the first step, the effect of temperature on L. monocytogenes growth rates was determined in duplicates at 13 temperatures between 2 and 43 degrees C by turbidimetric methods and adjusted by a quantitative secondary model. Then, seven sets of growth kinetics were collected by challenge testing in white pudding and roulade, both cooked pork products prepared according to an industrial process and stored at suboptimal temperatures ranging from 2 to 20 degrees C. In the second step, objectives were to (i) collect direct information on the temperature effect of L. monocytogenes on the two pork products, (ii) compare the two products regarding L. monocytogenes exposure, and (iii) compare results given by modeling (step i) with results obtained independently and then evaluate the model application domain. Each kinetic was built with at least 10 experimental data and two replicates. Comparison between L. monocytogenes behavior at 4 degrees C on white pudding and roulade indicated that both meat products were affected by food safety problems. Indeed, after contamination and storage for 10 days at 4 degrees C, the bacterial population increased by 2 log CFU/g in both products. Comparison between growth kinetic simulations and experimental data obtained separately gave satisfactory conclusions; the difference between observed and predicted bacterial population values was always less than 1 log CFU/g and a bias factor of 1.18 when growth rates were compared. These results applied to L. monocytogenes contamination of white pudding or roulade can now be used either in the management of optimal process and distribution networks or in risk assessment (exposure assessment).     

Timing and aging: Slowing of fastest regular tapping rate with preserved timing error detection and correction.

This study assessed motor limits of regular tapping, timing error detection, and correction in 60 participants aged from 19 to 98 years. Rate limitations on motor production were estimated from the average inter-tap interval when tapping as fast as possible for 30 s. Timing error detection required participants to judge whether a sound sequence presented at a slow, intermediate, or fast speed contained an irregularity because of phase shift. This was performed with or without synchronizing to the sounds. On the basis of the just-detectable positive phase shift (JND), participants synchronized with sequences containing phase shifts that were subliminal, just detectable or supraliminal. On average, JNDs were 9% of the inter-onset interval and by and large were not affected by synchronization tapping. Speed of error correction was estimated from the number of tones to return within 20% of the preshift synchronization error. Consistent with previous findings of motor slowing with aging, the fastest inter-tap interval increased with age. However, there was no age-related decline in JNDs or speed of error correction, both of which reflect predictive abilities for intervals within the motor repertoire of human adults. These results point towards intact timing error processing up to an advanced age. In assessing timing abilities in the brain of older adults, it is important to differentiate between motor slowing and its impact on rhythmic behavior (e.g., walking pace) from anticipatory mechanisms ('what to expect when') and how these are used to adjust the timing of actions ('what to do when'). (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A branch-and-cut algorithm for the partitioning-hub location-routing problem

We introduce the Partitioning-Hub-Location-Routing Problem (PHLRP), a hub location problem involving graph partitioning and routing features. The PHLRP consists of partitioning a given network into sub-networks, locating at least one hub in each sub-network and routing the traffic within the network at minimum cost. This problem finds applications in deployment of an Internet Routing Protocol called Intermediate System–Intermediate System (ISIS), and strategic planning of LTL ground freight distribution systems. We present an Integer Programming (IP) model for solving exactly the PHLRP and explore possible valid inequalities to strengthen it. Computational experiments prove the effectiveness of our model which is able to tackle instances of PHLRP containing up to 20 vertices.     

What you see is not what you get: single-family house renovation and energy retrofit seen through the lens of sociomateriality

Representing 30% of the energy consumption in Sweden, the built environment is a clear contender for climate mitigation initiatives. The substantial stock of single-family houses presents ample opportunities to engage in energy-saving refurbishments. However, despite political pressure, only a minority of these refurbishments includes low-energy retrofit. To explain this slow take-off, studies have mostly focused on the necessity to better link new technical solutions with user needs and behaviours. We propose to extend this analysis to a broader set of actors including the craftsmen contracted to carry out the refurbishments and the houses themselves with their specific features and characteristics. To do so, we build our contribution on the concept of sociomateriality. This perspective argues that technological artefacts are socially constructed, but recognizes that materiality also has a role to play. Drawing on the experiences of 24 small craftsman firms, 8 houses as well as their owners, our method comprises interviews, workshops and participant observation complemented by an in-depth case study. The results show many differentiated representations of the renovation process under scrutiny. All these representations need to be understood and to a certain degree aligned in order to achieve successful retrofits.     

Reduction approaches for robust shortest path problems

We investigate the uncertain versions of two classical combinatorial optimization problems, namely the Single-Pair Shortest Path Problem (SP-SPP) and the Single-Source Shortest Path Problem (SS-SPP). The former consists of finding a path of minimum length connecting two specific nodes in a finite directed graph G; the latter consists of finding the shortest paths from a fixed node to the remaining nodes of G. When considering the uncertain versions of both problems we assume that cycles may occur in G and that arc lengths are (possibly degenerating) nonnegative intervals. We provide sufficient conditions for a node and an arc to be always or never in an optimal solution of the Minimax regret Single-Pair Shortest Path Problem (MSP-SPP). Similarly, we provide sufficient conditions for an arc to be always or never in an optimal solution of the Minimax regret Single-Source Shortest Path Problem (MSS-SPP). We exploit such results to develop pegging tests useful to reduce the overall running time necessary to exactly solve both problems.     

A Surface Plasmon Resonance Optical Fibre Sensor for Testing Detergent Cleaning Efficiency

The objective of this paper is to report a feasibility study on the use of optical fibre and surface plasmon resonance (SPR) for determining detergent efficiency. The concept presented comprises a miniaturised dip‐sensor for enabling automated on‐line testing. In this way, the effect of formulation, concentration and temperature on the cleaning behavior of various surfactants and commercial cleaners is investigated. For this purpose, the decladded core of an optical fibre was sputtered with gold and afterwards coated with defined layers of stearic acid or animal fat to obtain a kind of model soil. The deposition of stearic acid was performed using a Langmuir–Blodgett through, and the sensor followed on‐line the deposition of the respective monolayers by UV/VIS spectroscopy, appearing as a distinct and constant shift in wavelength. Moreover, functional coatings were applied above the gold layer to achieve a variation of the hydrophilicity of the sensor surface. The SPR sensor proved to be easy to use, accurate and flexible. It offers a new solution that could replace the existing methods for detergency sensing and with a customised design it could be a useful industry tool since the small size of the dip sensor promises massive testing. The experiment also showed that functionalising the sensing zone could act as a way to mimic the potential substrates for cleaning.     

Development of an accurate and sensitive gas chromatographic method for the determination of acrolein content in Calvados and cider

Acrolein can be at the origin of an important organoleptic defect in beverages made from apples. Its content was investigated in freshly distilled Calvados and cider. The specificity of 3-methylbenzothiazolone hydrazine (MBTH) towards carbonyl compounds was used in order to derive acrolein in azines. Azines were separated and detected by gas chromatography coupled with a nitrogen-phosphorus Detector. Results showed that acrolein concentrations could be quickly determined in either Calvados or cider. Accuracy of quantification was better than 6% for concentrations about 1 mg/l in freshly distilled Calvados and 10% for concentrations about 10 μg/l in ciders. Acrolein content was found between 0.7 and 5.2 mg/l in samples of freshly distilled Calvados whereas it was between 7 and 15 μg/l in samples of cider. This method of quantification was applied to study disappearance kinetics of acrolein in cider. Acrolein content was found to decrease rapidly during the first hours and to change very slowly after a few days. Its behaviour during a distillation was also investigated showing that in spite of its high volatility it could also be found in the last fractions of distillation.