Adaptive control scheme for uncertain time-delay systems

The paper exposes some of the potential of a recently introduced backstepping transformation for linear uncertain time-delay systems to address the classic problems of equilibrium regulation under partial measurements, disturbance rejection, parameter or delay adaptation. For each of these problems, an implementable control strategy is proposed. It is analyzed through a convergence analysis of infinite dimensional dynamics, based on a transport partial differential equation representation of the estimated input delay and the mentioned backstepping transformation. The considered controllers contain this representation of the system, under the form of a distributed parameter system, and use it to determine relevant adaptation strategies. An illustration example is proposed.     

Intermittent hemodialysis treatment in cefepime‐induced neurotoxicity: Case report,pharmacokinetic modeling,and review of the literature

Cefepime is a broad‐spectrum cephalosporin indicated for in‐hospital treatment of severe infections. Acute neurotoxicity, an increasingly recognized adverse effect of this drug in an overdose, predominantly affects patients with reduced renal function. Although dialytic approaches have been advocated to treat this condition, their role in this indication remains unclear. We report the case of an 88‐year‐old female patient with impaired renal function who developed life‐threatening neurologic symptoms during cefepime therapy. She was treated with two intermittent 3‐hour high‐flux, high‐efficiency hemodialysis sessions. Serial pre‐, post‐, and peridialytic (pre‐ and postfilter) serum cefepime concentrations were measured. Pharmacokinetic modeling showed that this dialytic strategy allowed for serum cefepime concentrations to return to the estimated nontoxic range 15 hours earlier than would have been the case without an intervention. The patient made a full clinical recovery over the next 48 hours. We conclude that at least 1 session of intermittent hemodialysis may shorten the time to return to the nontoxic range in severe clinically patent intoxication. It should be considered early in its clinical course pending chemical confirmation, even in frail elderly patients. Careful dosage adjustment and a high index of suspicion are essential in this population.     

Comparing central location test and home use test results: Application of a new criterion

Choosing a consumer test methodology is critical for any company sensory scientist. However, we lack tools for comparing the outcome of consumer tests. Here we intended to develop a new comparison criterion based on a concept borrowed from metrology: robustness. We tested this concept with hedonic ratings data obtained from a central location test (CLT) on one hand and from a home use test (HUT) on the other hand. Two fermented milk beverages were tested and both tests were conducted with 240 subjects. The beverages differed in fat and sugar content. The comparison of the CLT and HUT data sets (both in monadic sequential) indicates that the method has a significant effect on the degree of liking. Indeed, the liking scores are lower with CLT than with HUT. Still, both tests lead to the same conclusion that the product with the higher fat and sugar content is significantly more liked. Besides, we developed three graphic representations that illustrate the results stability faced with the decrease in the panel size. These graphs show that CLT yields more robust results than HUT. Additionally the leading role of the panel size is emphasised for both tests. Our data show that the results from the two methods may change as soon as 20 subjects are removed from our original data set. These results that were not unexpected illustrate a fact which is often underestimated in practice.     

Interactivity Improves Usability of Geographic Maps for Visually Impaired People

Tactile relief maps are used by visually impaired people to acquire mental representation of space, but they retain important limitations (limited amount of information, braille text, etc.). Interactive maps may overcome these limitations. However, usability of these two types of maps has never been compared. It is then unknown whether interactive maps are equivalent or even better solutions than traditional raised-line maps. This study presents a comparison of usability of a classical raised-line map versus an interactive map composed of a multitouch screen, a raised-line overlay, and audio output. Both maps were tested by 24 blind participants. We measured usability as efficiency, effectiveness, and satisfaction. Our results show that replacing braille with simple audio-tactile interaction significantly improved efficiency and user satisfaction. Effectiveness was not related to the map type but depended on users’ characteristics as well as the category of assessed spatial knowledge. Long-term evaluation of acquired spatial information revealed that maps, whether interactive or not, are useful to build robust survey-type mental representations in blind users. Altogether, these results are encouraging as they show that interactive maps are a good solution for improving map exploration and cognitive mapping in visually impaired people.     

Cultural differences,experience with social networks and the nature of “true commitment” in Facebook

Formed on an analysis of design practices, the behaviour chain model stipulates that social network designer’s ultimate aim is to encourage users to adopt the social network site by entering a phase of true commitment. During this phase, social network users are driven to connect to known or unknown others by engaging in instrumental uses that create value and content and involve others, while staying active and loyal by investing time in the site. This paper investigates how designer’s intentions, as captured by the behaviour chain model, materialise through users’ reported practices in the social network site Facebook. A total of 423 Facebook users from 5 countries answered a questionnaire that allowed us to examine how 2 user characteristics, experience with the site, and culture, shape the nature of true commitment. Our findings show that experience with the site and even more so, culture, have an effect on users’ motivations for using Facebook, as well as their instrumental uses and the time they invest on the site. This analysis reifies the behaviour chain model by allowing designers to understand how the features they design are embodied in users’ practices.     

Surface characterisation of the Dome Concordia area (Antarctica) as a potential satellite calibration site, using Spot 4/Vegetation instrument

A good calibration of satellite sensors is necessary to derive reliable quantitative measurements of the surface parameters or to compare data obtained from different sensors. In this study, the snow surface of the high plateau of the East Antarctic ice sheet, particularly the Dome C area (75°S, 123°E), is used first to test the quality of this site as a ground calibration target and then to determine the inter-annual drift in the sensitivity of the VEGETATION sensor, onboard the SPOT4 satellite. Dome C area has many good calibration site characteristics: The site is very flat and extremely homogeneous (only snow), there is little wind and a very small snow accumulation rate and therefore a small temporal variability, the elevation is 3200 m and the atmosphere is very clear most of the time. Finally, due to its location, it is frequently within view of many satellites. VEGETATION visible blue channel data (0.43-0.47 μm) of a 716×716 km² area centred on the French-Italian Dome Concordia station, during the 1998-1999, 1999-2000, 2001-2001, and 2001-2002 austral summers were cloud masked and atmospherically corrected. The snow surface Bidirectional Reflectance Distribution Function is very high with little spatial and seasonal variability, which is a major advantage for sensor calibration. The inter-annual variation is found to be very small, proving that the stability of the site is very good.     

Why on Earth Can People Need Continuous Recycle Membrane Reactors for Starch Hydrolysis?

Classically enzymatic hydrolysis of starch is conducted in batch reactor in a two-step process including liquefaction and saccharification. This paper presents some ideas to simplify this process and decrease its cost. Because today, either saccharifying enzymes able to attack native starch or strong liquefying catalysts leading to sufficient low-molecular weight hydrolysates may be easily found on the market, one can imagine to develop a one-step process just involving a unique species of enzymes. The process can also be improved by operating in a continuous way and reusing enzymes. Among the various reactors, the continuous recycle membrane reactor, briefly CRMR, seems to be the most attractive since it allows to perform hydrolysis while separating at the same time syrups from enzymes and non-hydrolyzed starch.     

Novel Real-Time PCR Method To Detect Escherichia coli O157:H7 in Raw Milk Cheese and Raw Ground Meat

Raw milk, raw milk cheeses, and raw ground meat have been implicated in Escherichia coli O157:H7 outbreaks. Developing methods to detect these bacteria in raw milk and meat products is a major challenge for food safety. The aim of our study was to develop a real-time PCR assay to detect E. coli O157:H7 in raw milk cheeses and raw ground meat. Well-known primers targeting a mutation at position +93 of the uidA gene in E. coli O157:H7 were chosen, and a specific TaqMan-minor groove binder probe was designed. This probe targets another mutation, at position +191 of the uidA gene in E. coli O157:H7. The first step in the study was to evaluate the specificity of this probe with 156 different O157:H7/NM strains and 48 non-O157:H7/NM strains of E. coli. The sensitivity of the method was evaluated by pre- and postinoculation of cheeses and meat enrichments with different E. coli O157:H7 strains. All the E. coli O157:H7 isolates tested were positive, and none of the other bacteria were detected. Our results indicate that this method is sensitive enough to detect 10(2) E. coli O157:H7 isolates per ml of cheese or meat enrichment broth (24 h at 41.5° C) and is more sensitive than the International Organization for Standardization reference method. We can conclude that this new real-time PCR protocol is a useful tool for rapid, specific, and sensitive detection of E. coli O157:H7 in raw milk and raw ground meat products.