Cooperative requests and replies in a collaborative dialogue model

In this paper, we present a computational model of dialogue, and an underlying theory of action, which supports the representation of, reasoning about and execution of communicative and non-communicative actions. This model rests on a theory of collaborative discourse, and allows for cooperative human–machine communication in written dialogues. We show how cooperative behaviour, illustrated by the analysis of a dialogue corpus and formalized by an underlying theory of cooperation, is interpreted and produced in our model. We describe and illustrate in detail the main algorithms used to model the reasoning processes necessary for interpretation, planning, generation, as well as for determining which actions to perform and when. Finally, we present our implemented system.Our data are drawn from a corpus of human–human dialogues, selected and transcribed from a day-long recording of phone calls at a phone desk in an industrial setting (Castaing, 1993). We present an analysis of this corpus, focusing on dialogues which require, in order to succeed, helpful behaviour on the part of both the caller and the operator.The theoretical framework of our model rests on the theory of collaborative discourse developed by Grosz and Sidner (1986, 1990), Grosz and Kraus (1993, 1996), and further extended by Lochbaum (1994, 1995). An important objective guiding the design of our dialogue model was to allow the agent being modelled to interpret and manifest a type of cooperative behaviour which follows Grosz and Kraus's formalization of the commitment of each collaborative agent towards the actions of the other collaborative agents. The model we propose extends Lochbaum's approach to discourse processing in extending her interpretation algorithm to allow for the treatment of a wider range of dialogues, and in providing an algorithm of task advancement which guides the generation process and allows for the interleaving of execution and planning, thereby facilitating cooperation among agents. The cooperative behaviour of the agent being modelled rests on the use of communicative actions allowing agents to share additional knowledge and assist each other in performing their actions.     

Effect of water content on the mobility of solute molecules and of protein side chains in casemate preparations

The effect of water content on the mobility of small solute molecules and of casein side chains was studied by electron spin resonance in caseinate/water systems. The immobilization of nitroxide probes of different sizes and properties were followed during progressive dehydration of concentrated caseinate preparations (3 g H₂O/g dry protein). Above a characteristic minimum moisture content a linear relationship was observed between the rotational diffusivity and water content. The slope of the straight lines depended upon the size of the probe and upon the nature of the interactions with the protein. Nitroxide labels were covalently bound to caseinate and the changes in the flexibility of the side chains as hydration changed were followed. The results are discussed in relation to the solvent properties of water, and to recent suggestions concerning the significance, for stability, of the glass transition phenomenon in such materials.     

Elimination of Listeria monocytogenes in soft and red smear cheeses by irradiation with low energy electrons

Soft and red smear cheeses are frequently contaminated by Listeria monocytogenes , sometimes at relatively high concentration (< 10⁵ CFUg^-1). This bacterium is radiosensitive (D₁₀ value of approximately 0.45 kGy) but irradiation of the whole cheese by X-rays induced off-flavours when the dose exceeded 1.0 kGy. Irradiation could be effective in eliminating L. monocytogenes only from lightly contaminated cheeses (> 10²CFU g^-1).
L. monocytogenes appears only in the rind (where the pH is greater than 6.3) and never grows in the core of the cheese. Under these conditions, a specific irradiation of the rind after ripening, with a low-energy electron beam at relatively high doses (up to 3.0 kGy), allows the total elimination of L. monocytogenes in heavily contaminated samples (10⁵-10⁶ CFU g^-1) without noticeable modifications of the organoleptic properties of the cheese.     

PUBLIC UNDERSTANDING OF FOOD RISK ISSUES AND FOOD RISK MESSAGES ON THE ISLAND OF IRELAND: THE VIEWS OF FOOD SAFETY EXPERTS

Food safety experts have a key role in constructing food risk messages and thus their perceptions will influence how food risk issues are communicated to the public. This research examined the perceptions of food safety experts regarding public understanding of food risk issues and food risk messages on the island of Ireland. It also looked into expert views of the barriers to effective food risk communication and how to improve food risk messages. One hundred and forty‐three experts, working in areas related to food safety, completed an online questionnaire. Questionnaire and statement design was guided by the results of four in‐depth interviews with food safety experts. The findings indicate that most experts surveyed have little confidence in the public's understanding of food risk issues, their assessment of food risks, their ability to deal with scientific information and their food safety practices. Experts are of the view that the public under‐assesses the risk associated with some microbiological hazards and over‐assesses the risk associated with other hazards such as genetically modified organisms (GMOs) and bovine spongiform encephalopathy. The opinion of experts with regard to GMOs is not supported by previous consumer research. Experts noted that the level of education and age were important determinants for the level of understanding of food risk issues and messages. Experts were of the view that early intervention via school curricula was the best method to improve public understanding of food risk messages in the long term. Furthermore, experts are of the view that the media have the ability to improve awareness and knowledge about food risk issues but believe that the media tend to communicate information that is misleading. The majority of experts also believe that they should communicate uncertainty but are not confident that the public is able to cope with this uncertainty. Many of the experts also indicated a desire for training on how to interact with the media. The results may be used by those experts who are involved in the construction of food risk messages to improve the design and communication of food risk messages.     

Defined Starter Cultures used for Fermentation of Salmon Fillets

The integration of defined starter cultures into a fish fermentation process was studied. Six lactobacilli and 5 staphylococci strains were tested in a salmon model system. Dependence of bacterial growth and pH reduction on sucrose, NaCl and sodium nitrite concentrations, and fermentation temperature was evaluated. A combination of Lactobacillus sake and Staphylococcus carnosus was then applied to whole salmon fillets to which NaCl and sucrose had been added. The influence of sucrose and NaCl concentrations, temperature and the addition of sodium nitrite on pH, color and microbiological stability was evaluated. Optimal conditions were 25g-kg^?1 NaCl, 15gkg^?1 sucrose, fermentation at 12°C for 3 days, subsequent storage at 4°C.     

AN IN SITU METHOD TO STUDY THE REACTION CATALYZED BY ALKALINE PHOSPHATASE ON DNPP

The reaction catalyzed by alkaline phosphatase on disodium‐p‐nitrophenyl phosphate was studied in a reaction media composed of sucrose (43.5 and 53.5%, w/w) and sucrose (43.5%, w/w) + polysaccharide (10%, w/w) added with agar‐agar (0.5%, w/w) at low temperatures (20, 0 and ?5C). The results show that temperature and concentration of sucrose and sucrose + dextran in the media affect the enzymatic reaction. The presence of 10% dextran (molecular weight of 10⁴ g/mol, w/w) in the reaction medium decreased the reaction rate. This could be explained by the increase in the viscosity of the medium, due to the presence of this polysaccharide. The experimental data were compared with predicted values, calculated from Atkin's theory. The results show that in our experimental conditions described previously, the reaction catalyzed by alkaline phosphatase cannot be predicted by Atkin's theory, probably because the viscosity was not the main parameter governing the reaction.     

Thermomechanical Properties of Frozen Sucrose Solutions

A thermomechanical (TMA) method was used to study the glass transition of dry amorphous sucrose and the physical changes occurring when frozen sucrose solutions were heated. A modified TMA device allowed the detection of changes in sample dimension and compliance. Results of the TMA study of sucrose solutions suggested that the maximum solute concentration of the amorphous solution was close to 80% (w/w). In nonmaximally freeze concentrated solutions, devitrification generally started at the glass transition temperature of the amorphous phase and continued up to -32°C, where melting of ice crystals began, inducing softening and flow. With dilute solutions, ice recrystallization occurred in the temperature range from–32 to - 10°C. Devitrification and recrystallization had a stabilizing effect on mechanical properties.     

Feasibility of detecting trabecular bone around percutaneous titanium implants in rabbits by in vivo microfocus computed tomography

Objectives: The goal of this study was to examine the feasibility of in vivo imaging of trabecular bone around titanium implants by means of microfocus computed tomography (micro‐CT) and the use of rabbits for this purpose. Materials and Methods: Ten male rabbits type Hollander, received a titanium implant (1.7 mm diameter and 10 mm length) in the trabecular bone of the left tibia. Seven weeks later a micro‐CT scan was taken. Four rabbits were used to monitor potential harmful effects from X‐ray absorption until 4 weeks after scanning. A second group of six rabbits was used for testing the hypothesis that a good correlation exists between in vivo micro‐CT images and histological images of trabecular bone around titanium implants. The six rabbits were scanned and sacrificed immediately. The tibias were extracted and submitted to standard histological procedures. This resulted in a total of 12 histological sections and their corresponding 12 micro‐CT images. Bone area measurements were performed at the left and right side of the implant in three regions: 0–500, 500–1000 and 1000–1500 μm distance from the implant interface. Intra‐class correlations (ICC) were calculated between both techniques. Results: The four rabbits did not show any sign of radiodermatitis 4 weeks after scanning. In the micro‐CT images of the group of six rabbits, trabeculae are visible, but not well defined, due to the presence of noise in the image. The ICC for the right implant side were 0.44 for zone 0–500 μm, 0.48 for zone 500–1000 μm and 0.40 for zone 1000–1500 μm. The ICC for the left implant side could not be calculated. Conclusion: A low agreement was found between the bone measurements from histology and in vivo micro‐CT images. The use of the in vivo micro‐CT for trabecular bone imaging around metallic implants should be restricted to track tendencies in follow‐up studies.