Le dialogue homme- machine en langue naturelle : un défi ?

The implementation of a natural language manmachine dialogue in a data base or knowledge base query system is a difficult task. We present hereafter three different approaches to this problem : dialog modeling, exemplified through a linguistic scheme and several computational implementations ; the cooperation principles in a dialog and their associated algorithms ; and, lastly, the artificial intelligence approach based on speech acts theory and the techniques for generating and recognizing plans. We conclude by assessing the possible use of current speech processing techniques and by listing still unsolved problems.     

VITALITY OF CIDER YEAST GROWN MICRO-AEROBICALLY WITH ADDED ETHANOL,BUTAN-J-OL OR ISO-BUTANOL

Vitality and viability of an alcohol-tolerant wine yeast, used in cider production, were assessed after exposure to alkanol(s) during growth. Criteria employed were: methylene blue reduction, ability to form colonies on yeast extract-peptone-glucose agar medium, glucose driven proton efflux rates (“acidification power”), fermentative (CO₂ output) rates and adenylate energy charge values. We also monitored the maintenance of transmembrane electrochemical potential across the plasma membrane as measured by flow cytometry and by scanning confocal laser microscopy of oxonol dye exclusion. Growth rates were diminished by a third by 7.5% (v/v) added ethanol, 1% butan-1-ol or 1.4% iso-butanol. Exposure to 10% (v/v) ethanol gave 16% loss of “viability”, as measured by methylene blue reduction, during the first 20 h of growth. For 1% butan-1-ol, 50% loss of “viability” occurred over 40 h, whereas a similar effect of iso-butanol took 55 h. Adenylate charge values were high (<0.8) in growing cultures, remained high in early stationary phase but declined to 0.4 after 115 h. These values were hardly affected by 5 or 7.5% (v/v) ethanol whereas 10% or 15% (v/v) ethanol gave values of 0.58 and 0.16 after only 5 h exposure. 1% butan-1-ol or iso-butanol decreased adenylate charge values to a greater extent than 10% (v/v) ethanol, with the straight chain alcohol the more potent. Oxonol exclusion indicated that the vast majority of colls with greatly diminished vitality have maintained the plasma membrane potential values required to retain viability, despite extensive exposure to alkanol(s). Thus loss of ability to reduce methylene blue indicates diminished vitality but is not a reliable index of loss of viability. “Acidification power” was a more sensitive indicator of vitality than adenylate charge values. When mixtures of C₂ + C₄ alcohols were employed effects were generally additive rather than synergistic.     

Parallel multipole implementation of the generalized Helmholtz decomposition for solving viscous flow problems

The evaluation of a domain integral is the dominant bottleneck in the numerical solution of viscous flow problems by vorticity methods, which otherwise demonstrate distinct advantages over primitive variable methods. By applying a Barnes–Hut multipole acceleration technique, the operation count for the integration is reduced from O(N²) to O(NlogN), while the memory requirements are reduced from O(N²) to O(N). The algorithmic parameters that are necessary to achieve such scaling are described. The parallelization of the algorithm is crucial if the method is to be applied to realistic problems. A parallelization procedure which achieves almost perfect scaling is shown. Finally, numerical experiments on a driven cavity benchmark problem are performed. The actual increase in performance and reduction in storage requirements match theoretical predictions well, and the scalability of the procedure is very good. Copyright © 2003 John Wiley Sons, Ltd.     

Management of antidiabetic medications in overdose

The drugs used to treat diabetes mellitus are diverse and involve several classes. However, these drugs can be roughly separated into hypoglycaemic agents, such as insulin and the sulphonylureas, and antihyperglycaemic agents, such as the biguanides, the alpha-glucosidase inhibitors and troglitazone. Reports of insulin overdose are rare. The major effects of insulin overdose are secondary to the insult to the CNS produced by hypoglycaemia. The mainstay of insulin overdose management is glucose replacement therapy. Sulphonylureas are the most commonly used oral antihyperglycaemic agents in the management of type 2 (non-insulin-dependent; NIDDM) diabetes mellitus. Sulphonylureas primarily cause serum glucose reduction by stimulating the release of preformed insulin from the pancreatic islets. The mainstay of sulphonylurea overdose management is glucose replacement therapy, and in severe cases, reduction of insulin release. In the large majority of patients intravenous glucose supplementation will be sufficient to maintain euglycaemia. Repaglinide, a meglitinide analogue, is a new nonsulphonylurea oral hypoglycaemic agent. In overdose, this drug may produce prolonged hypoglycaemia similar to the sulphonylureas. The primary problem with biguanide overdose is the potential for lactic acidosis. The management of biguanide overdose is largely supportive and directed at correcting the metabolic acidosis along with associated complications. The alpha-glucosidase inhibitors, acarbose, voglibose and miglitol competitively and reversibly inhibit the alpha-glucosidase enzymes (glucoamylase, sucrase, maltase and isomaltase) in the brush border in the small intestine, which delays the hydrolysis of complex carbohydrates. They appear unlikely to produce hypoglycaemia in overdose, but abdominal discomfort and diarrhoea may occur. Troglitazone is the first thiazolidinedione antidiabetic drug available. There are no data on overdose, probably because of its very recent introduction. Overdoses with antidiabetic drugs produce major morbidity, with many cases requiring intensive care medicine and prolonged hospital stays. However, fatalities are rare when treatment is initiated early. The management of the hypoglycaemic drugs (insulin and sulphonylureas) is based primarily on restoring and maintaining euglycaemia via intravenous dextrose supplementation. In the case of the sulphonylureas, reduction of insulin secretion via pharmacological intervention may also be necessary. With biguanides the main risk appears to be cardiovascular collapse secondary to profound acidosis. The management focus is on restoring acid-base balance with hyperventilation and the use of insulin to shift the utilisation of glucose from the nonoxidative pathway to the oxidative pathway. Use of haemodialysis has shown equivocal results but may be valuable in metformin overdose.     

Design of adaptive feedforward algorithms using internal model equivalence

The paper investigates the design of adaptive feedforward cancellation (AFC) algorithms with sinusoidal regressors for repetitive control. Such adaptive algorithms are equivalent to linear controllers based on the internal model principle (IMP). Using this equivalence and root locus rules, the phase advance of the regressor of the adaptive algorithm can be chosen to maximize the phase margin at low gains. A surprising result is that selecting the optimal phase advance is equivalent to placing a zero in the open right half-plane in certain cases. A complete design and analysis for the compensation of a single-frequency periodic disturbance is done. A new variation of the AFC algorithm is also developed in which the adaptive portion acts in parallel with a feedthrough term. the IMP equivalent of this algorithm has two zeros instead of one. Analysis and simulation show this method to have superior convergence and robustness properties when compared with the method having no feedthrough term. Discrete time versions of the algorithms are briefly considered.     

The active site of Trichoderma reesei cellobiohydrolase II: the role of tyrosine 169

Trichoderma reesei cellobiohydrolase II (CBHII) is an exoglucanasecleaving primarily cellobiose units from the non-reducing endof cellulose chains. The ß-l,4 glycosidic bond iscleaved by acid catalysis with an aspartic acid, D221, as thelikely proton donor, and another aspartate, D175, probably ensuringits protonation and stabilizing charged reaction intermediates.The catalytic base has not yet been identified experimentally.The refined crystal structure of CBHII also shows a tyrosineresidue, Y169, located close enough to the scissile bond tobe involved in catalysis. The role of this residue has beenstudied by introducing a mutation Y169F, and analysing the kineticand binding behaviour of the mutated CBHII. The crystal structureof the mutated enzyme was determined to 2.0 Å resolutionshowing no changes when compared with the structure of nativeCBHII. However, the association constants of the mutant enzymefor cellobiose and cellotriose are increased threefold and for4-methylumbelliferyl cellobioside over 50-fold. The catalyticconstants towards cellotriose and cellotetraose are four timeslower for the mutant. These data suggest that Y169, on interactingwith a glucose ring entering the second subsite in a narrowtunnel, helps to distort the glucose ring into a more reactiveconformation. In addition, a change in the pH activity profilewas observed. This indicates that Y169 may have asecond rolein the catalysis, namely to affect the protonation state ofthe active site carboxylates, D175 and D221.     

Custody evaluation practices: A survey of experienced professionals (revisited).

W. G. Keilin and L. J. Bloom (1986) explored 70 issues related to child custody evaluation practices. The current study replicates Keilin and Bloom's study and looks at an additional 42 items. Two hundred and one psychologists from 39 states were surveyed about 112 aspects of child custody evaluation practices. The analysis was divided into evaluation practices, sole-joint custody decision making, and recommendations. Comparisons between the findings of this study and those of Keilin and Bloom are made. The current practice of child custody evaluations is reported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hierarchical approach to modelling of liquid-crystalline polymers

Summary Liquid-crystalline polymers exhibit fascinating structure at many size scales. This paper describes how computer models at different size scales can be linked together by a hierarchical approach to give a better understanding of the properties and behaviour of these materials. The atomic scale is considered first, where semi-empirical molecular orbital techniques are used to calculate the torsional energy functions associated with rotating the backbone bonds of the polymer. Secondly, entire chains are simulated using a Monte Carlo technique based on the torsional energy functions to deduce the persistence length of the polymer of interest. A theoretical relationship enables the Frank elastic constants to be determined from the persistence length. The elastic constants may then be used as input parameters for models both to predict microstructure and to help understand the role of defects in the shear flow of these materials. The hierarchical approach provides a meaningful framework within which data obtained from small-scale models are used to parameterise models at a larger scale.     

Beyond the Crisis Window for Reform: Some Ramifications for Implementation

In the policy literature, crises are often presented as opportunities for reform initiation. Little is known, however, about the effects that crises may have on the implementation of such reform initiatives. This article explores how a crisis may affect the administrative relations between central authorities and field administrations. The crisis impact on central-field relations appears to be twofold. First, a crisis may facilitate, if not induce, the centralization of decision-making processes. Secondly, a crisis may affect the degree of consensus between central authorities and field administrations with regard to problem definitions and preferred solutions. This paper uses a case study of the Dutch prison system to explore the crisis impact on these two dimensions of central-field relations. In this particular case, crisis circumstances did not facilitate a successful implementation of a major policy overhaul. We suggest that crises may offer opportunities for reform implementation, but only under highly restricted conditions. When these conditions are not met, crises may have perverse effects on central-field relations which limit the prospects for the effective implementation of reform.