Zoran Budimac

Zoran Putnik
email: putnik@im.ns.ac.yu

Mirjana Ivanovi

Klaus Bothe

Kay Schuetzler

Conducting a Joint Course on Software Engineering Based on Teamwork of Students

Keywords: common course, self-assessment, teamwork

For the previous six years, under the auspices of the "Stability Pact of South-Eastern Europe" and DAAD, a joint project for developing a course in "Software Engineering" has been conducted. The intention of the project was to enable usage of shared materials for software engineering courses at a wide range of universities in participating countries. During school-year 2004/05, for the first time the same course, with the same case study, and the same assignments has been conducted at the Humboldt University Berlin, and the University of Novi Sad. In this paper, we share some of the experiences obtained through conducting the same course in the two school-years: 2004/05 and 2005/06.

Introduction

During the year 1999, as a part of cooperation between professors from Humboldt University in Berlin and University of Novi Sad, an idea emerged for cooperation in creating and developing common courses in certain fields of computer science. Since the idea very much coincided with the trends in European higher education, some other universities from South-Eastern Europe, with which we already had some collaboration, have been included in the project. Under the auspices of the "Stability Pact of South-Eastern Europe" and "DAAD -Deutscher Akademischer Austausch Dienst" this project has lasted for six years now (Bringing Curriculums and Equipment Up To Date, 2002;SE Course Homepage).

Currently, there are thirteen universities from eight countries participating in the project. Humboldt University of Berlin, Germany; University of Novi Sad, Republic of Serbia; University "Cyril and Methodius", Skopje, FYROM; and University of Plovdiv, Bulgaria, are the "core" members. Besides, Universities of Belgrade, Niš, and Kraguje-vac from Republic of Serbia; University of Zagreb and University of Rijeka from Croatia; Universities of Banja Luka and Sarajevo from Bosnia and Herzegovina; Polytechnics University of Timisoara from Romania; and University of Tirana from Albania are included in the project (Zdravkova et al., 2003a;[START_REF] Zdravkova | The structure of SETT-Net[END_REF][START_REF] Budimac | International educational project -some experiences[END_REF].

Besides the final goal of academic reconstruction of South-Eastern Europe, the project established some other goals:

• inclusion of "Software Engineering" course as a core one into universities' curricula in South-Eastern European countries; • gaining of consensus in creation of a joint "Software Engineering" course, and determination and selection of appropriate software engineering topics as the basis for the common pool of topics; • creation and development of joint teaching and exam materials for selected software engineering topics: slides, case-studies, assignments, exam questions, literature, etc. and • establishment of research and education framework as the basis for the future cooperation.

These goals are implemented mostly through cooperation in creation, improvement and enhancement of teaching materials, and production of a distributed, Internet-based, multilingual university course.

The work on the project has been performed in a threefold manner:

• continually, during the preparation for classes and exercises, lecturers try to innovate and to improve and enhance the existing teaching material; • each year, during the winter break, representatives of the "core" universities meet to prepare a plan of further activities for the current year, and decide how to distribute assignments, in order to obtain maximum efficiency; • annually, the project members attend a workshop. At the workshop, all participants give presentations about the results they achieved, and the duties they fulfilled during the previous school year. Furthermore, many presentations give new insights and ideas for further work and possible improvements in effort to create common teaching materials (not only in the domain of software engineering, but also in some other project community courses: programming languages, compiler construction . . .). So far, the following meetings have been organized:

- During the project, all partners played an active role in it, either by: • contributing to some part of the materials;

• using some topics or subsets of the joint course material in their lectures;

• writing review reports based on collecting students opinion and suggestions;

• presenting some new interesting SE topics;

• analyzing possibilities and proposing new directions in developing teaching material for other courses. The common software engineering course originated from the course that has been conducted at the Humboldt University in Berlin for several years. Its main goal was to present some introductory notions and principles of software engineering, including also a wide spectrum of sub-areas suggested by the ACM and IEEE societies (Computing Curricula, 2001) and others (SWEBOK, 2001). It has been shown that the original course held at the Humboldt University, covers more than 85% of the basic lessons suggested in "Curricular guidelines for undergraduate programs in computing" [START_REF] Bothe | Technical and managerial principles of a distributed cooperative development of a multi-lingual educational course[END_REF]. The course was to be held at higher years of computer science curriculum, after students become familiar with basics of (object-oriented) programming and other important fields of computer science.

The project was conducted in three partially overlapping phases: 1. During the first phase, teaching materials for existing topics were translated from German to English, and then, through the cooperation of all the participants, refined. 2. In the second phase, new interesting SE topics were developed. 3. In the third phase, it was anticipated to create local versions in national languages [START_REF] Bothe | Collaborative development of a multi-lingual software engineering course across countries[END_REF]. For the purpose of localization, a dedicated tool for work in a multi-lingual environment was developed [START_REF] Bothe | Tool support for developing multi-lingual course materials[END_REF]). The course is accompanied by a pool of case-studies to be discussed during lectures and processed through assignments. From this pool, lecturers from the project universities are free to select the most suitable one(s). In addition to this, there is a pool of assignments, referring both to the course contents and to the case studies, thus forming the base for specific exercises. Together with the assignments, sample solutions, correction hints, and typical errors are collected. Through these several additions, a great flexibility is added to the course.

The rest of the paper is organized as follows: In the second section, the technique used for assignment solving in teams is described. In the third section, experiences with students' solutions of assignments both in Berlin and in Novi Sad are presented. The fourth section presents an idea that emerged in Novi Sad of self-assessment between students, members of the same team, and explains teamwork organization in more details. Finally, in the fifth section, some conclusions and discussions of common insights gained so far by conducting the same teaching material at two Universities (Berlin, Novi Sad) are given.

Experiences of Teaching SE in Two Different Countries

Parts of the joint course (individual topics or complete subsets) have been taught to students in the six universities that participated in the project. However, for the first time during the school year 2004/2005, a complete, absolutely identical course, with the same case studies, and the same assignments for students was held in Germany (Berlin) and in Serbia (Novi Sad). The course was being presented to the students of the fourth, final year of study, with more or less similar pre-knowledge, with the similar number of classes for the similar type of subjects. In addition, a form of self-evaluation inside student teams was introduced in the course in Novi Sad, which is the key contribution of this paper.

The same course lasts for one-semester in Berlin (7th) and for two semesters (7th and 8th) in Novi Sad. Still, the total number of classes is the same at both Universities. The number of students attending the course at the Humboldt University was 78, while there were 58 students in Novi Sad. The same lecture style was adopted in the subsequent school years at both Universities, and now we are able to compare the experiences and draw some conclusions based on the experiences in teaching the course twice in two consecutive school years: 2004/05 and 2005/06.

Lectures in Novi Sad were held in Serbian, while slides presentations used were in English (this was the students' decision). Lectures and slides of presentations used in Berlin were presented in German. At both institutions, read-only handouts were put on local sites -after each lecture -the Serbian and English versions in Novi Sad, and the German version in Berlin. Also, lectures lasted the same for each topic, except for "Software process models" and "Cost estimation" that lasted longer in Novi Sad, due to personal preferences and the decision of the lecturer.

During the entire course, students have to solve seven relatively small assignments. To do that in an appropriate SE manner, they are divided into teams, according to their own choice. This approach has several advantages [START_REF] Bielikova | Experiences with designing a team project module for teaching teamwork to students[END_REF]). The first is simplicity from the managerial point of view. Second is that opportunity for a student to sign up for the team of her/his choice creates a tendency to base the choice on personal relationships. Thus, the time needed for adjustments and adaptation of team members is drastically shortened. Third, efficiency of teams created in this manner tends to be rather high.

All of the mentioned advantages are inclined to minimize most of the real-life problems arising. Teams do get started without additional effort, extra meetings are much easier organized if students know each other -and often have similar preferences, and usually there is a natural pressure on team members "not to disappoint their friends". The only obvious disadvantage of this approach is a risk that team quality can (and usually does) vary significantly.

In Berlin there were 26 teams having up to three persons in each team, while in Novi Sad there were 12 teams, each having four or five members. Later, in the second year, due to the increased number of students, in Novi Sad 15 teams of four or five students were created. The same assignments were given to each team, which were to be solved in three weeks. The assignments were as follows:

1) review of "preliminary requirements specification" and "requirements specification", 2) application of the function-point method on a given preliminary requirements, 3) review of a product model developed after structured analysis, 4) development of a part of a static model, through creation of a use-case diagram, and a class diagram for a given problem, 5) review of a solution of the 4th assignment of a different team, 6) definition of formal specification (Z and algebraic) for several given operations, and 7) installation, testing of and commenting on a tool for software quality metrics. The main reason for this type of work is a widely accepted objective of a good teaching style and appropriate curriculum -to prepare students for their professional career, to make them able to survive the ever changing demands of the surrounding world, and to make them capable of solving complex, demanding tasks. One of the recognized practices is to involve teamwork in education, as it is critical for solving the complexity of software tasks. The most valuable points we hoped our students would acquire were: to show abilities to work and communicate within a team, and to cooperate sufficiently to plan and develop the needed output of their project.

Some Observations about the Assignments

In practice, assignment solving functions as follows: Teams are given tasks and expected to produce results in a given time (no less than three weeks). Each member of a team is expected to read, think about, and reflect on a task before the team meeting, so that the whole team is prepared for discussing and solving the task through (possible) several meetings. After all the solutions are submitted and evaluated by lecturers, one class is organized where the most interesting and provoking solution is presented by the members of the team, that submitted it.

The solution presented is either the "best", or the "worst", or simply the "best defended" by creators. A class is organized so that one team presents their solution and the rest of the students are involved in discussing, criticizing, glorifying, or simply commenting on it, while the lecturer is just a moderator of the discussion. After the presentation, the "proper" solution is pointed out -if such a thing exists in software engineering -by a lecturer, i.e., a solution collected by several years of combined experience of Humboldt and Novi Sad Universities.

A number of points have been awarded to each assignment. In Germany, a student must earn at least 50% of the points to enter the final exam, where these points are of no interest anymore. In Novi Sad, the similar condition holds, but the earned points directly influence the final mark.

Typical students' errors and omissions were almost the same at both universities. The same stands for the distribution of points among teams.

For example,

• The first assignment -review of preliminary specifications -was the most vague (as it is, after all, also in real life) for both groups of students, producing the whole spectrum of observations. • Connected to the same assignment we observed that the mark for the first assignment was the best mark of each team, compared to their other marks.

• For the second assignment -application of the function-point method -no team received the maximal number of points at both universities ever. • Solutions to the second assignment produced very different values for function points ranging from 170-300, with the similar common errors and omissions. • Similar observation can be made about other results that were required. Value for the man/month ranges from 1.6 to 3.2. Values for influencing factors in connection with other applications were ranging from 0 to 5, i.e., through the whole scale. Still -the function point method is in theory characterized as a very subjective method, so this kind of results has been expected. • Errors in the second assignment (if any), were connected to the same thing -not recognizing either the complex function that should be divided into several functionalities, or several simple functions that actually produce a single functionality (and should be therefore treated together). • The third assignment -review of a product model developed after structured analysis -had a twofold importance. Schemes of Data Flow Diagrams were taken from a software engineering essentials book [START_REF] Balzert | Lehrbuch der Software-Technik[END_REF], including all errors.

It was a part of an attempt to convince students that even in a book and much more in real life, errors and omissions occur in software engineering documents and models. • The second task for students in the third assignment was to try to find the errors and correct them. The results were very good -more than 90% of teams gained more than half of the points. • The third assignment was in both institutions the most interesting one because of over-creative results. Considering themselves "experienced software engineers" by now, there were several teams that were more interested in creating their own solutions, than in finding errors in the existing solution (their original task). Moreover, those teams "requested" better marks for their creations. • The fourth and fifth assignments were obviously connected, and teams produced similar solutions. It was the second half of the course when this assignment was given. Students had already gained some experience, so even when they produced errors in their solutions, they defended those errors reasonably and knowledgeably. • The fifth assignment -review a solution of another team -will be discussed in more details in the following section, concerning the relationship among teams, and between teams and lecturers. • The last two assignments -formal specification, and installation and testing of a software package -were quite straightforward, and did not cause too many problems to students. Their main purpose turned out to be collection of additional points and improvement of the final mark. Yet, we would like to emphasize here that by this time, all of the teams had enough points to pass this part of the exam.

In Fig. 1 are presented results of assignment evaluation for the assignments in Berlin and in Novi Sad for the two finished years. Results of the third year are still not available. At the end, all of the teams collected more than 60% of the points, so that there was no problem with fulfilling the requirements for the exam. In Berlin, all of the teams fulfilled the required tasks and collected more than 50% of points -as most of them usually do each year.

In Fig. 2 the total percentages of points gained for the assignments in Novi Sad are given.

It is interesting to note that there were teams that stopped doing the exercises as soon as they acquired the minimum number of points needed. In addition, while usually everyone met criteria as long he/she stayed with the course, there were teams or persons who left the course during the semester (some not taking the exam at all). As far as the statistical data is concerned, gained points ranged from 62 to 93 percent of the total amount available both in Novi Sad and Berlin.

It is also interesting to mention that sessions where solutions were discussed, analyzed, and criticized, always provoked arguing and strong exchange of opinions. This produced very creative classes. As can be found in various readings, in order to create a realistic environment, the amount of freedom and supervision during the teamwork process should be balanced. Simulating reality, a high degree of freedom should be given to students in their solutions, discussions, and opinions. Yet, since students usually have little or no experience with (large) projects and teamwork, some level of monitoring, guidance and supervision is needed to ensure advancements and successful results.

The main argument of the teams was that the specification of problems and appropriate documentation that were the subject of their assignments were 'imprecise' and 'vague'. In fact, this was their first contact with the real-life problems, where there are no definite solutions. These sessions became a significant part of the whole course -exchanging ideas and opinions, and seeing different solutions helped students to see the real-life problems more clearly. The comparison of obtained results and solutions of students' tasks in other universities and in other courses, together with realization that they thought similarly, proved to be reassuring to students. In their own words, they felt "satisfied because their thinking, judgment, and ideas were correct."

Teamwork and Self-Assessment

As mentioned earlier in the paper, a form of self-evaluation of student teams was performed in Novi Sad. For assignment types used in this course, where each team was required to produce a 5-20 pages long report on their solution, depending on the type of assignment, it was impossible to "cheat". Still, we were worried that team members would not be equally involved, and would not equally contribute throughout the whole process of solving a given task. We were interested to find out how they felt about that, and eager to try to teach them to value good teamwork, and recognize a bad one.

Besides trying to find out if there were sleeping members inside teams, we tried to develop among students a feeling for teamwork, self-assessment and assessment of their team colleagues. Inspired by [START_REF] Srikanth | On pair rotation in the computer science course[END_REF], where the similar principle was applied to pair programming, we asked students to fill in anonymously a questionnaire assessing the contribution of other team members to the final result. Each member of a team answered the following questions about the other members of his or her team:

• Did each team member read the assignment and the preparation material before the beginning of teamwork? • Did each team member made an equal contribution to the final solution?

• Did each team member explicitly and creatively contribute to the final solution?

• Was each team member cooperative during the work?

The answer for each question was given as a number of points -between 0 and 25. They were promised that those marks would not be shown to other members of the team, to ensure their honesty, and that they would not influence their final mark, and would be used only for research purposes. Although two years are a relatively short period for a more formal statistical evaluation of the self-assessments, we can present some preliminary experiences.

With each assessment, lecturers pleaded the team members not to "cover" their nonworking colleagues, and reminded them that agreeing to give each other higher marks would add nothing to their exam marks. Still, it seems that those pleas didn't have much effect. The following numerical results give the reason for this statement:

• 67% of marks were maximum -25 points.

• Additional 21% of marks were 20 points or more -again "excellent" marks.

• Two teams gave each other maximum number of points for each assignment, to each member. • Another five teams gave each other such marks that the average mark for each member of a team was higher than 20 points. Fig. 3 presents results of a team self-assessment. Still, if we disregard two teams with average marks of 25, all of the other teams showed the same trends:

• In each team, there was always the "best" member, and the "worst" member. The best member had 2-5 marks lower than 25, while the worst member had 10 or more marks lower than 25. Even though those marks were still rather high (mostly over 20) the difference was evident. • The person who was marked as the best was usually the one to give lower marks most freely to the other members of a team. This person was not necessarily the "team leader" (selected by students), yet it was not unusual that she/he would give the leader a much lower mark. • In the opposite case, the person who was given the lowest marks by her or his colleagues would usually give the other team members all the highest marks. We guess that it was a way to try to achieve better marks for oneself. • There was an equal number of students whose marks changed in either direction: students that started inferior, but received much higher marks later, and students that started "perfect", but gained only 5-10 points on later assignments. • An interesting, while not that important, note can be made about the distribution of the marks. As students are also "mathematicians", the round marks 5, 10, 15, 20, and 25 cover 89% of all the marks. • Finally, as we expected, the worst marks were given to those students who were not regularly attending classes. Namely, students are required to attend 50% of classes in order to get the signature from the professor, verifying "regular attendance", ensuring enrollment into the next semester without an additional fee. While the percentage of students earning the signature is very high, considered normal for the students of the final year, those few who did not attend enough classes, were also marked by their colleagues with the lowest marks.

The trends present in assessments showed that at first the students were very friendly towards their colleagues, giving them only the best marks. Yet, as time went by, marks were beginning to lower, and become more regularly distributed. The only difference between the students is "how low" the lowest mark would go -yet, if we scale marks for the last assignments, we can see that they are leaning towards normal distribution.

Teamwork, especially in a variant of self-elected teams, has one additional advantage. During the two-semester work, we encountered several conflicting situations inside teams, including situations when a single member was excluded by a decision of the rest of the team. In our opinion, students who experienced such realistic situations are much better prepared for actual life and work situations, and for their professional career.

As discussed in [START_REF] Bielikova | Experiences with designing a team project module for teaching teamwork to students[END_REF], there is also a problem of the size of a team. Namely, the bigger the team is, the more difficult it is for its members to fully participate in all of the activities. So, subgroups are formed, individual roles become overlapping and unclear, all of this becoming a source of a possible additional conflict. On the other hand, if teams are too small, their creativity and flexibility of them decreases. In [START_REF] Bielikova | Experiences with designing a team project module for teaching teamwork to students[END_REF] the suggested team size is between 4 and 8 members, optimally 5 or 6. In our case, the decision was also led by our wish to make a better distinction between team-members, since points gained through assignment solving directly influenced their final mark. So we were inclining towards smaller teams, 4 members on the average.

Considering the assignments, we decided to follow the suggestions of our DAAD project and present each team with the same task, each time connected to the lectures presented earlier. Yet, one more experiment has been conducted. After each assignment, the gained team marks were presented to all of the students. After complaints about "low marks" for the first three assignments, we decided to ask students to mark their colleagues. So, teams with contradictory solutions were opposed to each other, anonymously, of course, yet none of the teams knew whose solution was good, or how many points they had gained. We asked them to discuss and evaluate the other solution as their fifth assignment. As we expected, yet as a great surprise for students, those marks were significantly lower than marks given by lecturers. On a bad side, this experiment showed that there were also few teams who were not quite sure about their solution, changed their views, and praised the completely opposite solution by another team. This showed that students tend to underestimate the complexity of a problem, while overestimating their knowledge and capacity.

Conclusion

General opinion of all of the project members is that the project was very successful and useful, mainly based on the following characteristics:

• Time for the course preparation is drastically shortened.

• Students are enabled to learn in accordance with contemporary contents, principles, and European standards. • Course compatibility, both general and concrete, is achieved.

• An excellent base for usage of distance learning principles is created.

• Experiences, methods, and learning activities of lecturers from several different countries are adopted. • Possibilities for different kinds of cooperation with the project participants are promoted.

Concerning experience obtained from teaching and exercising software engineering in the same way in Novi Sad and in Berlin, and the process of marking, teamwork, assessments, and self-assessments, we would like to emphasize a solid (or higher) dose of humor and good will shown both in the texts explaining the solution, and in the later discussions. This, together with a great amount of defending their attitudes, opinions, and positions on each of the questions and concepts, represents a mature and expert thinking from the students. We consider this as a good indication leading towards creation of persons capable of quality teamwork, persons aware of their abilities, responsibilities, and knowledge, thus prepared for working on a real-life software projects.

However, there are still a lot of open issues concerning this kind of teamwork. Organization of projects similar to real-life ones, trying to present industrial conditions, and time, cost, and resource restrictions is clearly desirable, but hardly an achievable and realistic goal. Still, software engineering course relying only on an academic environment could not be really successful, and should try to get at least some kind of "industrial", "real-life" involvement.

Moreover, it is interesting to notice that the two rather different types of students/professors/countries produced very similar results. Considering the pre-knowledge of the students, we think that it was very similar at both universities. Yet, lecturers in Berlin were performing the same course for the last sixth years, while in Novi Sad, the course has been held twice for undergraduate students, and twice for postgraduate students. In addition, University of Novi Sad, and specially Department of Mathematics and Informatics is going through reforms, the same as in the whole country, quite different to Germany.

An additional difference lies in the method of passing the exam. In Germany, a student is allowed to try to pass an exam only once, except with a medical confirmation of illness, when one additional attempt is allowed. Quite differently, until recently, in Serbia students were allowed to try to pass the exam an indefinite number of times, having around 10 exam periods during the year. Furthermore, students in Serbia have the right to have the exam on the same subjects that were presented to them several years ago, even though the course had been changed in the meantime. Starting from this year, according to Bologna declaration, students will be allowed to try to pass the exam exactly three times during one year. In addition, students gain points during the school-year, which make a part of the final mark.

The previously mentioned principles were used in the "Software engineering" course. More than 70% of the students passed the exam during the first two exam periods (for other courses, this percentage is around 35).

Two more interesting moments have to be mentioned. First, the common course in "Software engineering" is the first course at the Department of Mathematics and Informatics in Novi Sad using English slides as a basis for a course. This decision had no negative effect.

Second, a common practice in Novi Sad among students is that the best students "cover" for others, "not-so-good" students. Even if that means that a professor will not have a chance to distinguish between good and other students, it is a usual practice for good students to risk their own marks, trying to help others in cheating, or to cover for them by performing their duties. By insisting on anonymity, and explanations why this practice is wrong, in Novi Sad we tried to convince students to abandon it. Since this is the first course with such an intention, we are very pleased with the results.

With all of the mentioned differences, it is important to notice that the students reacted similarly, had the similar distribution of points, made the same errors, complained about similar issues, . . . Consequently, we believe that an introduction of teamwork was a good idea, worthwhile for students.

Z. Budimac is a professor at Faculty of Science, Department of Mathematics and Informatics, University of Novi Sad. He graduated in 1983 (informatics), received master's degree (computer science) in 1991 and doctor's degree (computer science) in 1994. His research interests include: mobile agents, e-learning, software engineering, case-based reasoning, implementation of programming languages. He has been project leader for several international and several national projects. He has published over 100 scientific papers in proceedings of international conferences and journals, has written more than 10 university textbooks in different fields of informatics. He is head of computer science chair.

Z. Putnik is a research assistant at Faculty of Science, Department of Mathematics and Informatics, University of Novi Sad. He received master's degree (computer science) in 2004. He is currently working on his doctor's degree in computer science at the University of Novi Sad. His research interest is currently focused on e-learning and virtual learning environments. He is a member of the Yugoslav Society for Applied and Industrial Mathematics, JUPIM, and European Association for Programming Languages and Systems.

M. Ivanović is a professor at Faculty of Science, Department of Mathematics and Informatics, University of Novi Sad. She graduated in 1983 (informatics), received master's degree (discrete mathematics and programming) in 1988 and doctor's degree (computer science) in 1992. Her research interests include: multi-agent systems, e-learning and webbased learning, data mining, case-based reasoning, programming languages and tools. She actively participates in more than 10 international and several national projects. She has published over 100 scientific papers in proceedings of international conferences and journals, has written more than 10 university textbooks in the field of informatics and ICT.

K. Bothe is a professor at the Institute of Informatics, Humboldt University Berlin. His research interests cover: compiler construction, software engineering, software testing methodology and tools, programming languages, e-learning, and logic programming. During the last years, he was the grantholder of an international DAAD project and of an EU Tempus project concerned with the development of a Joint Master's curriculum in software engineering and the construction of teaching material repositories. K. Schuetzler has been a consultant at BearingPoint since 2007. As a member of the Competence Group Integration Services in Public Services/Infrastructure Services he is mainly engaged in IT-consulting tasks. Prior he was employed by Humboldt-University Berlin, Germany as a research assistant at the Software Engineering Group of the Computer Science Department. He graduated in 2001 (computer science) at Humboldt-University Berlin. He is about to finish his doctoral studies in computer science within the next few months. As a research assistant in the Software Engineering Group Mr. Schuetzler was responsible for the organization of project seminars and exercise to the group's lectures. His research interests include: reverse and reengineering processes, requirements management, software quality assurance (including test) and software architectures.

  September 2001, The First Seminar on Teaching Software Engineering and Reverse Engineering (TSERE), Novi Sad, FR Yugoslavia; -September 2002, The Second Seminar on TSERE, Plovdiv, Bulgaria; -September 2003, The Third Seminar on TSERE, Ohrid, FYR Macedonia; -September 2004, The Fourth Seminar on TSERE, Zagreb, Croatia; -September 2005, The Fifth Seminar on TSERE, Baile Herculane, Romania; -September 2006, The Sixth Seminar on TSERE, Nesebar, Bulgaria.

Fig. 1 .

 1 Fig. 1. Results of assignments evaluation.

Fig. 2 .

 2 Fig. 2. Total percentage of assignment points in Novi Sad.

Fig. 3 .

 3 Fig. 3. Percentage of points gained per team during self-assessment.

Programinės irangos inžinerijos kurso mokymas taikant grupinio darbo metod a

Zoran BUDIMAC, Zoran PUTNIK, Mirjana IVANOVI Ć, Klaus BOTHE, Kay SCHUETZLER Paskutiniuosius šešis metus pagal Pietryči u Europos stabilumo sutart i ir DAAD buvo kuriamas bendrasis programinės irangos inžinerijos kursas. Šio projekto tikslas buvo suteikti daugumai bendradarbiaujanči u šali u universitet u galimyb e naudotis programinės irangos inžinerijos kurso medžiaga. 2004/05 mokslo metais pirm a kart a kursas išbandytas dvejose aukštosiose mokyklose: Berlyno Humboldto ir Serbijos Novi Sad universitetuose. Šiame straipsnyje aptariami tyrimo duomenys ( igyta patirtis) -analizuojamas šio igyvendinimas 2004/05 ir 2005/06 mokslo metais.


IMAGES CONSORTIUM MEETING

St Petersburg, April 25-28, 2010

Should someone do something concerning addiction?

The French GP's Answers

Chantal Mougin

In the beginning of 2008, I"ve been asked to manage General Practitioner"s (GP"s) focus groups in France. It has not been at all easy to gather GP"s but I finally achieved 7 French GP"s focus groups and I have been asked to speak here about that experience.

May be I'll explain here what a focus group is...

To be able to speak about what French GP"s said, I started to read the transcriptions of the 7 focus groups. I first would like to underline the subjective aspect of that reading, where I chose what I wanted to show, leaving a large range of items. I chose what seemed to me more important and what they predominantly spoke about. But I know Michael Egerer is preparing his thesis out of these data"s and I"m relieved to know that he will do a more serious job than mine.

The purpose of these focus groups was the RAGI questions. As it was the subject of Michael Egerer"thesis, I asked him first what I could speak about, not to do the same job twice… I told him about my intention to see how much women and men spoke differently.

But by reading the retranscriptions, it didn"t seem a relevant item.

So I came to the last of the six questions typed on a paper, in front of the GP"s, while they had to speak.

When presenting the focus groups method to GP"s, I specified they were not obliged to answer these questions. They could freely comment the films as they feel. These questions were just supposed to be a guide in case it helped their group comments… So I"ve read the 7 transcriptions of what they said, and I"ll start to point out that a large part of the comments try to explain why people are caught into addiction. Even if it wasn"t among the questions they were supposed to answer, it remains one of the main question: Why? Why do people get addicted until they ruin their own life and their families too?

I"ve chosen to study their answers to the last question upon the six they had, because the answers to that question gather more data"s than the others, on the one hand, and on the other hand because I feel it reflects an important aspect of GP"s ambivalent posture, having main consequences on their professional life, and then on their impact on addiction. It underlines their need to know what could help them to take care of addicts. It is surprising to notice the two first answers are exactly saying the opposite opinion. They are not that far equally long. It shows how great the ambivalence on that question is.

CNRS -CERMES3 -Équipe CESAMES

I"ll translate and summarize for you what they said:

1 -Yes, we can! That was the main message, the optimistic side, saying there is always something to do:

 We can help, we have to give a help, and we have to try. There is always a hope! Something is possible. We must not think there is nothing to do.

 We must keep our private discussions with these patients: that"s where we can convince them; then we can try to change something, we must do the necessary to help them to get out of it, whatever is occurring. Do something is our job: we have to explain, to ask questions if we suspect something. We kindly listen, to reduce anguish. To listen is very important. We have to take in account the human side, to help people to exist, to take in account their request, to bring a solution (I'm not sure the solution is elsewhere our offices). If we don"t listen, we can"t understand and we can"t change anything. Some patients are grateful, just to have been listened. We have to observe too, and to give advice. Never judge them but accompany, sometimes for years: we are sometimes the only firm frame in their lives. We must be trustworthy, so they can feel in confidence.

 The basic problem is their suffering and that"s what we have to face at. We have to be there, as a support, when they have nothing to hold on, when they suffer.

 We never can do better than to "knit" a relation, with substitution, until the addict can drop down his addiction. We are the transitional object, we can be ourselves their substitution, and we can work until we"ve done the job to separate them from their consumption. When we prescribe narcoleptic drugs, we are seen as "dealers" but we"re very watchful in our prescriptions. We search for a relief, for comfort.

 Sometimes we can send people to hospital  Twice I could make an alcoholic man stop drinking; being rude and announcing they would dye: it has been a success and they stopped.

 For bulimia, GP"s spoke about the liver transplant, as a solution. For gambling, they consider putting people into the care of a guardian is a solution too.

-No, we cannot. No way!

 We can do nothing; we don"t know how. There is nothing for us to do. There is no medical answer. We are pessimistic. How could we explain to an alcoholic he"s going to dye? I don"t feel able to take care of alcoholics. We are hung up! It is no use. Take care of alcoholics is much more difficult than our others patients. Each time I tried, it has been a failure. It is a huge job. There is so much to do to reduce that problem. We are not competent. We are powerless, helpless with alcoholics.

 Anyway they don"t ask to be cured. So we cannot give any answer. What to do? They don"t come to appointments. It is not easy for us. If they don"t ask to be helped, whatever we try will be a failure. These situations seem very desperate, awfully difficult. Taking care of them can last for years. I"m cheating and pretending to take care, for example in asking for a blood test or a biological check-up, just to keep them connected with a medical network. But when they understand what we are trying to do, they run away. I think we are allowed to give up, because they give up… What"s the use to go on trying? It is not our mission. It is their problem: I don"t care, because they do anyway what they want. And we don"t have to give standards of life. We are not the saviour. It is an utopia. I"d rather care innocent sick persons, who deserve to pay attention.

 We have not been trained for such serious pathologies, much more difficult and complex than others. We have nothing to give them, as strong as their drugs, as powerful. We cannot compete.

 We have to send people to more competent professionals.

May be you noticed main of these comments concern alcoholics. They are the people GP"s meet every day. So it is a problem they constantly face at, experimenting how difficult it is.

-The State / The Society

 Laws and orders should protect people.

 Should addiction be forbidden? Prohibition has never been a solution.

 For tobacco, there are taxes. Rising price of tobacco had an impact to reduce smoking. But does it really work with heavier addicts?

 The policies try but are inefficient to keep young people from drinking. They should forbid the entrance in pubs for the one younger than sixteen.

 The alcohol salesmen lobbies have invented new beverages to encourage young people to drink alcohol. Binge drinking is in fashion. On internet and in some newspapers, they say shit does not matter. So what can we say? It is a politic problem. It is a very old question: there must be a global answer, in which we could play our part.

 The political speeches say we have not been trained enough. Policies should send patients to us, instead of saying we are guilty. We are supposed to make prevention.

 For gambling, there should be special laws. Casino"s managers are gangsters. It is immoral. The State is the real gangster. Justice is the answer.

-Psychiatrists should take care

 It is their job. They can send alcoholics to hospital. But people are released the day after.

 Lots of addicts are psychotics. They are very difficult to cure. Some psychiatrists don"t intervene unless a murder occurs. Psychiatrists together with the Police have to take care.

 The gambler shown in the extract is a real psychotic one. It is the psychiatrists" field. He should be put by Justice into the care of a guardian.

-The addict is responsible: it is no use to try to help him

 They have lost control of their destiny  They refuse to be helped if not in hospital  Speaking about the alcoholic man of the first extract: "he could react and think it is not good for him to go on like that".

 If someone has no will, it is easy for us to give him substitution, but he will go on drinking and it will be worst for him.

 I accept to say the addict is responsible of his illness: if someone tries to help, they don"t listen: do they really want to be helped and to leave their addiction? We cannot find how to motivate them. If they don"t ask for a help, what to do? When they come at us, it is for something else 6 -The specialized centres for addicts must take care  Usually, I send them to centres for addicts. There are people who know what to do about that matter: I do not. Then I try to keep contact: in these detox centres; addicts are progressively deprived from drugs. I know a place where they do it very well. In hospitals, they take care of them well enough, but they choose the addicts they accept.

-Several professionals should intervene: social workers, organizations…

 There is a kind of agreement to fix with the patient: everything must be done together with addicts specialists, with the consulting physician and with the family. Trying to resocialize addicts is a huge medico-social problem, needing a multidisciplinary network of many intervening actors including the police, social workers, psychiatrists, GP"s, dieticians, associations, detox centres…  Our first job is to clear the demand, and then, to work with others.

-Prevention is important

 Is prevention possible? Can it be useful? GP's doubt about it. It seems difficult, may be impossible to prevent addicts to get worse.

 Why should it be the GP"s mission to make prevention? Ask some of them, in the one hand...  And in the other hand, another said: We have to meet the patient regularly, to meet the mothers, the young children parents. May be we can hope to leave a message, to be listened… May be it is our mission to find what is possible, to do it with those whose addiction is not yet too serious. If ever we can help, it would be by preventing.

-It is the Casinos' fault

 Some people are forbidden to gamble: it is a kind of prevention. But it is not taking care.

 Everything is conceived in Casinos to encourage people to gamble, to spend their money. That is the ambivalence: Casinos earn a lot of money from gamblers.

 With a medical certificate, I put gamblers into the care of a guardian.

-His wife could do something for her alcoholic husband

Several film extracts show or speak about the alcoholic wife or girlfriend, saying she abandoned him and it did not help, or showing her accepting to let her husband join his friend for a beer, "just one!".

 The alcoholic"s wife who abandoned him is responsible: she has not helped (it is in contradiction with the one who said GP's had to help the wife to run away). She is not consistent.

 The family is not very efficient.

 The wife who accepted to let her husband join his friends for a beer should have resisted, refused.

 Many women divorce because friends tell them they must not stand anymore alcoholism: the idea grows slowly in her mind…  The addict needs someone to give him a frame, to take care of his body, to convince him, not to abandon him, to be present…

-I don't know who should…

 Of course someone should do something, but who? I do not have the answer…  It is not easy to answer. I do not know. It is an eternal problem…

I gathered now what has been said concerning beaten women:

 While some pubs have been closed in France, men drink at home and their wives are beaten.

 We have to take care of beaten women: they are in danger; it is a very serious problem we have to face at. We are responsible and we have to protect children, families, to help the wife to run away.

 For beaten women, French Justice has a very strong reaction. There are special organizations for beaten women. They helped them quite a lot to get out of the situation. We must call a social worker, in case of a beaten woman with children, to find an apartment for them.

Conclusion

What could be the conclusion to close all these comments I displayed?

We can notice the GP"s ambivalence about our question: should someone do something concerning that problem? They balance between, on the one hand, not knowing what to do and who should, thinking it is impossible; and on the other hand, thinking and hoping they can do something. This second optimistic position comes more often. I wonder if it does not look like a principle, a kind of faith or a choice, or else they would not find any longer the motivation to carry on their job.

I would conclude saying they seem to need mostly to be informed about what can be done and what is existing. They should be informed of what could be their role and mission. It seems they feel an important lack of training about addiction. Addictology is a very recent discipline and I am not sure young physicians are yet trained to that matter. There is here a French urgency.


S Clain
email: clain@math.uminho.pt

J Rodrigues

NUMERICAL SIMULATIONS OF COUPLED PROBLEMS IN A VACUUM DISJUNTOR

Keywords: Finite element method, Contact problem, Domain decomposition method, Linear elasticity, Helmotz equation, Biot-Savard

In this work we carried out the modelling, the discretization and the numerical simulation of a vacuum breaker. We present a mathematical model of the multi-physical problem involving mechanical, electrical and electromagnetic phenomena. The finite element method is employed in conjunction with a technique of domain decomposition to solve the mechanical problem and the electrical problem while a direct integration of the Biot-Savart formula allows to compute an approximation of the magnetic field, hence the Lorentz-Laplace forces.

INTRODUCTION

A vacuum circuit breaker is a device that allows the cutting of electrical power. The apparatus core is essentially constituted of two electrodes, one of them being mobile and subject to a mechanical force produced by a spring, maintaining the contact between the two electrodes (see figure 2 left). The current passing between two electrodes is determined by the extension of the contact zone and generated Lorentz-Laplace forces in areas bordering the contact, but not yet in contact. Due to the curved geometry of the electrodes, Lorentz-Laplace forces are opposite and cause the repulsion of the electrodes. When the intensity reach a critical value, the forces separate the two electrodes and the circuit is breaking. For a given intensity, the equilibrium position and the contact area result from the balance between the spring constraint and the repulsive Lorentz-Laplace deriving from the electric and magnetic fields.

To determine the equilibrium, we have to consider three sub-problems, namely, the mechanical problem, the electrical problem and the magnetic problem. Indeed (see diagram in figure 1), the spring force in conjunction with the Lorentz-Laplace force determine the displacement of the two bodies and the contact area. From the contact area, we deduce the current density distribution and the electric field. With the current density, we compute the magnetic field and we deduce the Lorentz-Laplace force with the electric and the magnetic field. The goal of the present article is to present the modelling and the numerical simulation of each subgroup. In section 1, we present the multi-physical model for the circuit breaker divided in three sub-models. Section 2 is dedicated to the numerical method employed in each sub-model. We present the discretization of the mechanical problem using the finite element method coupled with the Mortar method. We also employ the finite element method to compute the electrical current assuming that the contact area is given. At last, we present the numerical method to compute the magnetic field based on the Biot and Savard formula to evaluate the Lorentz-Laplace forces. The section 3 concerns the numerical simulations for each sub-model of the vacuum circuit breaker.

MATHEMATICAL FORMULATION

We consider two electrodes in contact, as in figure 2. The bottom one is constituted by a piece of copper named Ω b fixed on a support foundation denoted by Γ B , the interface between the electrode and its support. The lateral sides of the electrode Ω b (denoted by Γ b L ) are free of constraint.

A second upper electrode, characterized by domain Ω a is maintained in contact with Ω b applied a force on the upper side of Ω a , named Γ U . To determine the force, we assume that the spring force is uniformly applied on the Γ U face with a prescribed constraint.

Since Ω a is mobile, the force will change with the displacement of Ω a . Like in Ω b , the lateral sides (denoted by Γ a L ) are free and no force or displacement are prescribed. At last, we denote by Γ a C and Γ b C respectively the two boundaries which are opposite and represent the potential contact between the two electrodes. We denote by n ℓ the outward normal vector and by t ℓ the tangential vector such that t ℓ , n ℓ is a positive oriented basis Since the contact boundaries are not fixed, we shall introduce a common parametrization of the contact interface. To this end, we begin to consider the initial situation where two bodies are not submitted to any constraint such that the potential contact area Γ a C is in front of the potential contact area Γ b C but no contact holds. To characterize Γ a C and Γ b C we introduce a local parametrization of the two boundaries χ a and χ b defined on interval

x y Spring Ω b Ω a Γ a L Γ b C Γ b L Γ b L Γ a L Γ a C Γ B Γ U
I = [0, 1] by χ a : I → Γ a C ; χ b : I → Γ b C ; ξ → χ a (ξ) ξ → χ b (ξ). (1)
For instance, we denote by n a = n χ a (ξ) and n b = n χ b (ξ) the respective parametrization of the outward normal vectors of Γ a C and Γ b C . Since the electrode have a small curvature with respect to the dimension of the electrode, we assume that they are collinear to the Ox 2 with n a + n b = 0. In the other hand, the interface displacements are perpendicularly and any contact point Y = (y 1 , y 2 ), in the new configuration when one applies forces, corresponds to a point

X a = (x a 1 , x a 2 ) ∈ Γ a C and a point X b = x b 1 , x b 2 ∈ Γ b C such that x a 1 = x b 1 = y 1 , in the initial configuration.
At last, we denote by g the initial gap between the two electrodes defined on I given by g

(ξ) = χ a (ξ) -χ b (ξ) n b (ξ). (2)

MECHANICAL PROBLEM

We assume that the two bodies are elastic and we denote by ε (u) the strain tensor for any displacement u(x) with respect to x in the initial configuration. The conservation of the impulsion reads

-div σ(u) = f in Ω
where f represents the body force. In our case, f will be constituted by the gravity and the Laplace forces. Using the classical elasticity framework for isotropic linear material with the Hooke's law, the stress tensor writes

σ = σ(u) = λtr(ε(u))II + 2µε(u) , (3)
where the Lamé positive constants λ and µ are given by (cf [?])

µ = E 2(1 + ν) and λ = Eν (1 + ν)(1 -2ν) ,
with the Young's modulus E > 0 and the Poisson ratio ν ∈ ]0, 1/2[. At the lateral sides Γ a and Γ b , no force and displacement are prescribed so we state σ n = 0 on Γ a L ∪ Γ b L . The bottom part of the electrode is fixed so we required that no displacement occur and we state u = 0 on Γ B . The upper part is controlled by the spring and the normal force is governed by

n T σ n = -κ(u • n + α)
where -κα is the initial force applied to the electrode while -κ(u • n) represents the force due to the displacement . Moreover we require that no lateral movement takes place, so we state u • t = 0 on Γ U to prevent the horizontal movement. Now we deal with the contact interface condition. For a given configuration (spring and body force ) the interfaces Γ a C and Γ b C move and we obtain two new interfaces Γa C and Γb C which are partially in contact and the new configuration presents a commune interface

A = Γa C ∩ Γa C .
The active set is characterized by the interval J, such that for any ξ ∈ J:

(u a .n a ) • χ a (ξ) + (u b .n b ) • χ a (ξ) = g(ξ), (4)
and

(t aT σ(u a )n a ) • χ a (ξ) = (t b T σ(u b )n b ) • χ b (ξ) = 0, (5)
(n aT σ(u a )n a ) • χ a (ξ) = (n b T σ(u b )n b ) • χ b (ξ) < 0. ( 6
)
On the free part of the interface, characterized by ξ ∈ I\J, (no contact) we have:

(u a .n a ) • χ a (ξ) + (u b .n b ) • χ b (ξ) < g(ξ) (n aT σ(u a )n a ) • χ a (ξ) = (n b T σ(u b )n b ) • χ b (ξ) = 0 (t aT σ(u a )n a ) • χ a (ξ) = (t b T σ(u b )n b ) • χ b (ξ) = 0
Note that the contact boundary is unknown and J has to be also determined.

ELECTRICAL PROBLEM

We model the current density J ℓ , the electrical field E ℓ and the scalar electrical potential V ℓ e in each electrodes, ℓ ∈ {a, b} by

E ℓ = -grad V ℓ e , J ℓ = σE ℓ ,
to obtain the classical potential formulation

-∇ • (σ∇V ℓ e ) = 0. ( 7
)
We prescribe the current of intensity I 0 on boundary Γ U and assume a uniform repartition of the density current such that we have

J a • n = I 0 |Γ U | on Γ U where |Γ U | represent the length of the interface.
We also prescribe the null potential on the bottom interface setting V b e = 0 on Γ B . At last, since no current crosses the lateral interfaces, we set

∂V ℓ e ∂n = 0 on Γ ℓ L . Since we solve the scalar potential in each sub-domain, we have to prescribe the electrical condition on the active subset and the free subset for the contact interface. As for the lateral side, we prescribe

∂V ℓ e ∂n = 0 on Γ ℓ C \ A while we enforce the continuity of the electrical potential and the current on the active set

V b e -V a e = 0 on A (8) J b • n b + J a • n a = 0 on A. (9)

MAGNETIC PROBLEM

The calculation of the magnetic field B of current system is carried out with the BiotSavart formula for two-dimensional geometries Ω ∈ R 2 as [START_REF] Suh | The evaluation of the Biot-Savart integral[END_REF]. The magnetic field at a point x is given by

B (x) = - 1 2π Ω j(y) ∧ ∇ ln(|y -x|)dy, (10)
for a current j flowing in the direction of e 1 and e 2 . Equation (10) writes

B (x) = e 3 2π Ω det[j(y), (x -y)] |x -y| 2 dy. (11)
Let us denote by T ℓ h the triangulation in cell C of the domain Ω ℓ with ℓ = a, b and T h = T a h ∪ T b h . In this study, we assume that the two domains are symmetric such that the nodes on the on each contact zone Γ a C and Γ b C correspond and we introduce the interval I to provide a common parametrization of the two contacts interfaces. M h denote the mesh of interval I such that the nodes of I, Γ a C and Γ b C corresponds. In future works, we intend to remove this constraint employing the Mortar technique [START_REF] Rodrigues | The mortar finite element method with Lagrange multipliers[END_REF][START_REF] Bernardi | A new non conforming approach to domain decomposition: The mortar element method[END_REF] or the three-field domain decomposition method [START_REF] Brezzi | Macro hybrid elements and domain decomposition methods[END_REF].

MECHANICAL PROBLEM

At rest, the two contact interfaces are given by the χ ℓ (ξ) functions from which we deduce the gap function [START_REF] Bernardi | A new non conforming approach to domain decomposition: The mortar element method[END_REF]. The configuration at rest correspond to the reference configuration. After applying the spring pressure, the gravity and the Lorentz-Laplace forces, we obtain a new configuration characterized (in the reference configuration) by an active zone A ℓ ⊂ Γ ℓ C . One has to provide the active zone such that relations (4) and ( 5) have to be both satisfied with the constraint condition (6). To solve the mechanical problem, we use a domains decomposition technique [START_REF] Haslinger | A domain decomposition algorithm for contact problems: analysis and implementation[END_REF]. To this end, we denote by A ℓ k ⊂ Γ ℓ C a candidate for the active zone characterized by J k = [ξ k l , ξ k r ] where χ ℓ (ξ k l ) correspond to two opposite nodes of Γ ℓ C on the left of the contact zone and χ ℓ (ξ k r ) correspond to two opposite nodes on the right.

Γ C a Γ C b I A ξ l ξ r

The Lagrange Multiplier problems

For the meshes T a h , T b h and M h we consider the associated discrete spaces

V a h = {ϕ = (ϕ 1 , ϕ 2 ) continuous linear piecewise on Ω a such that (ϕ 1 ) |Γ U = 0}, V b h = {ϕ = (ϕ 1 , ϕ 2 ) continuous linear piecewise on Ω b such that (ϕ) |Γ B = (0, 0) T }, W h (J k ) = {ψ continuous linear piecewise on J k }.
Moreover, for any ψ ∈ W h (J k ), Π k ℓ (ψ) denotes the projection of ψ on the contact boundaries A ℓ k such that Π k ℓ (ψ)(P ) = 0 for all the nodes in Γ ℓ C \ A ℓ k . We propose the iterative procedure to determine the configuration when enforcing relations ( 4) and [START_REF] Suh | The evaluation of the Biot-Savart integral[END_REF]. To this end, we denote by U n ∈ W h (J k ) a given normal displacement on J k , we consider the Lagrangian augmented problem, for

ϕ ∈ V a h Ωa σ(u h ) : ε(ϕ) dx+κ Γ U (u a h .n a )(ϕ.n a ) ds = Ωa f .ϕ dx+κα Γ U (ϕ.n a ) ds+ A a k Π k a (λ a h )ϕ 2 ds
where λ a h is Lagrange multiplier associated to the normal displacement constraint, for all

ψ ∈ W h A a k (u a h .n a )Π k a (ψ) ds = J k U n ψ dξ.
The second Lagrangian augmented problem writes for all ϕ ∈ V b h

Ω b σ(u h ) : ε(ϕ) dx = Ω b f .ϕ dx + A b k Π k b (λ b h )ϕ 2 ds
where λ b h is Lagrange multiplier associated to the normal displacement constraint, for all

ψ ∈ W h A b k (u b h .n b )Π k b (ψ) ds = J k (g -U n )ψ dξ
to satisfy condition (4). The contact problem is solved if one can determine the normal displacement U n such that λ a h = λ b h on J k .

Resolution of the contact problem for J k given

We proceed with the description of the iterative procedure to solve the contact problem. Let U (m) n be a predicted displacement, we compute the associated Lagrange multipliers λ a h and λ b h given by section 3.1.1. Then we consider the two problems

Ωa σ(w a h ) : ε(ϕ) dx + κ Γ U (w a h .n a )(ϕ.n a ) ds = A a k Π k a (λ a h -λ b h )ϕ 2 ds
and

Ω b σ(w b h ) : ε(ϕ) dx = A b k Π k b (λ a h -λ b h )ϕ 2 ds.
We then set for each node ξ j of M h

U (m+1) n (ξ j ) = U (m) n (ξ j ) - θ 2 (w a h .n a ) • χ a (ξ j ) + (w b h .n b ) • χ b (ξ j ) .
For θ > 0 small enough, the procedure converges to the solution (see [START_REF] Haslinger | A domain decomposition algorithm for contact problems: analysis and implementation[END_REF]).

Determination of J

For a given J k we solve the contact problem but the constraint (6) which predict a negative normal stress on the contact is not necessary achieved. The strategy consists in taking J 0 = I as the initial guess and if (6) is not satisfied with J k , we reduce the domain removing the first and the last node of J k to construct J k+1 .

ELECTRICAL PROBLEM

We now assume that the active zone A is given and we consider two sub-problems and we denote by V h the interface potential at the contact zone define on A as a continuous linear piecewise function. We formulate the discrete problem in the following way. Find V a h continuous, linear piecewise on Ω a such that

Ω a ∇V a h .∇φ dx = Γ U J a (s)φ(s) ds (12)
with V a h = V on A. To satisfy to current density continuity, we consider the second problem find V b h continuous, linear piecewise on Ω b such that

Ω b ∇V b h .∇φ dx = - A σ∇V a h .n b (13)
with V b h = 0 on Γ B . We then deduce the voltage V h → G(V h ) = V b h on A which provide a one-to-one map on the nodes of A. The solution of the electrical problem is reached when G(V h ) = V h and we solve the fix point problem using the iterative procedure

V k+1 h = V k h + G(V k h ) 2 (14)
setting V 0 h = 0.

MAGNETIC PROBLEM

Let j ℓ = σ∇V ℓ h the constant piecewise approximation of the density current on each cell and P i a node of the mesh. We compute the magnetic field at the node with

B i = B(P i ) = e 3 2π C k ∈T h |C k | det[j(M k ), M k P i ] |M k P i | 2
where M k is the centroid of cell C k , |C k | the cell area and j(M k ) the constant vector in C k . From the magnetic field, we deduce an approximation of the Lorenz-Laplace force

f (P i ) = σE(P i ) ∧ B i
where E(P i ) is an interpolation at node P i with the piecewise constant vectors E k = ∇V h|C k on the neighbour cells.

We present some numericals results obtains with the schemes presented in the previous section. We consider a problem where the the gravity and the Lorentz-Laplace forces can be neglected with respect to the spring pressure characterized by κ = 10 8 and α = -0.05. We first solve the contact problem to determine the active zone A. Figure 4 shows the displacement vectors for the two elastic bodies (left) and we present on the right a zoom in the contact zone. From, the contact interface previously computed by the mechanical In figure 6, we plot the e 3 component of the magnetic field. Since the current flows to the bottom, we check that the magnetic field is positive on the left side (red area) and negative on the right side (blue area).

CONCLUSIONS

We have presented a two-dimensional model of the vacuum disjunctor where we have taken into account the mechanical, the electrical and the electromagnetic problems. Numerical schemes have been designed to compute an approximation for each sub-problem. The next step consists in linking the three sub-problems via the Laplace-Lorentz force to provide the equilibrium solution for a high current intensity where the repulsive force are predominant to determine the contact area.

Figure 1 :

 1 Figure 1: The circuit-breaker modelling: a coupling of three mathematical sub-problems

Figure 2 :

 2 Figure 2: The circuit-breaker and the geometry

Figure 3 :

 3 Figure 3: The contact zone: before applying forces (left), after applying forces (right)

Figure 4 :

 4 Figure 4: Displacement : global view (left), zoom at the contact interface (right)

  Figure 5 gives the density current distribution in the two domains and the zoom view clearly show the half loop of the electric current in the vicinity of the contact zone which is responsible of the repulsion forces.

Figure 5 :

 5 Figure 5: Current density distribution : global view (left), zoom at the contact interface (right)

Figure 6 :

 6 Figure 6: Magnetic field distribution (componant following e 3 ):global view (left), zoom at the contact interface (right)


Mirjana Devedži
email: mdevedzic@yahoo.com

Vladan Devedži
email: devedzic@galeb.etf.bg.ac.yu

Towards Web-Based Education of Demography

Keywords: Web-based education, reusable learning objects and standards, teaching and learning technologies for WBE, demography

This paper describes steps taken towards introducing Web-based educational technology in teaching demography at the university level. Traditionally, demography is taught by giving lectures to the students, who are then expected to study from textbooks and exercise in demographic calculus. Some students find this way of learning monotonous and exhausting, hence their motivation gradually drops. Modern learning technology can help prevent such a situation, at least to an extent. Of course, using any technology to support teaching and learning requires representing essential parts of the domain knowledge with that technology first. The paper presents initial results in building such a knowledge infrastructure for Web-based education (WBE) in the domain of demography.

Introduction

The importance of demographic studies increases progressively in the last 50 years, and so does the interest in integrating quantitative and theoretic knowledge of human population [START_REF] Clarke | Population Geography[END_REF][START_REF] Pressat | Demographic Analysis: Methods, Results, Applications[END_REF][START_REF] Hinde | Demographic Methods[END_REF]. Currently, demography as a scientific discipline is taught mostly at universities, since it requires a certain level of maturity and prerequisite knowledge higher than that at high-school level. On the other hand, learning demography requires mastering of a number of abstract concepts and specific skills are required in order to progress in learning effectively. Unfortunately, traditional textbookand-exercise way of learning such a discipline is not always effective.

This results in the need to introduce other approaches in teaching and learning in this domain. WBE has proven to be effective as a teaching and learning approach in a number of other disciplines, and it can especially increase the students' motivation when learning abstract concepts. From the teachers' perspective, it requires keeping up with the progress of technology in their own studies, and supports avoiding staleness in their knowledge and pedagogical skills. From the learners' perspective, it supports pro-active studying and systematic adoption of the domain knowledge.

We have taken several steps in order to gradually introduce WBE in teaching and learning demography at our university. First, a team of software professionals has built a Web classroom -a network-based technological support for learners that will help them utilize current Web technologies to grasp domain concepts more easily. Initial practical experience with the Web classroom in learning topics from other domains is extremely encouraging [START_REF] Šimić | Building an intelligent system using modern internet technologies[END_REF]. Second, we want to introduce the technology of Web-based intelligent tutoring systems (ITS) [START_REF] Brusilovsky | Adaptive and intelligent technologies for Web-based education[END_REF] in the Web classroom, so that adaptive and personalized learning will be supported. Finally, we are in the process of building Web-based knowledge infrastructure to enable easy creation of teaching material, intelligent support for learning, and reuse of learning resources.

Web Classroom

Our Web classroom is a client-server learning environment designed as in Fig. 1. Students and teachers work in a real or in a virtual classroom; in both cases, students learn individually and Web technology connects the server and the client sides. The Web classroom differs from more conventional computer-based learning in several aspects. First, it is an intelligent learning environment (an ITS), with built-in pedagogical module that guides the learning process. It also maintains a student model for each student registered with the system at any time. The student model stores all the necessary parameters about the specific student, such as his/her learning goals, learning history, learning style and other preferences, current level of topic/course mastery, and the like. Moreover, Web classroom's adaptivity and personalization in learning-material presentation ensures for adaptive, learner-centered individualization of the learning process. Finally, note that it is not necessary for the students and the teacher to sit at their computers at the same timethe built-in tutor (pedagogical module) takes over the role of the teacher in most sessions.

There are two major actors in this environment: the student on the client side, and the teacher on the server side. There are four modes of a student's interaction with the Web classroom: "Authentication" (logging in for a new session), "Learning" (selecting one of the material to learn from and reading the corresponding illustrated lessons; some of the lesson pages are filled with text and graphics, and some of them also have supporting audio and video clips), "Assessment" (answering questions the system asks after the learning of a lesson is completed), and "Validation" (the mode in which the system checks and updates the student model by estimating the student's knowledge about different topics from the material he/she was supposed to learn).

The teacher is on the server side. His/her tasks include authentication, starting the server, monitoring the students' sessions, editing the domain knowledge (learning material) and stopping the server. Of course, these tasks are rather diverse (system administration, authoring, teaching, and assessment), hence in practice they are done by several specialists. Some of the tasks are very different from those on the student side -for example, editing the domain knowledge, which is allowed only to the teacher. In this mode, the teacher adds, edits or deletes the learning and assessment material. A specific server-side module, also accessible only by the teacher, is used for monitoring the students' sessions.

The server exhibits enough intelligence to arrange for personalization of the learning tasks it supports. In fact, from the learner's perspective the server appears to act as an intelligent tutor with both domain and pedagogical knowledge to conduct a learning session. It uses a presentation planner to select, prepare, and adapt the domain material to show to the student. It also gradually builds the student model during the session, in order to keep track of the student's actions and learning progress, detect and correct his/her errors and misconceptions, and possibly redirect the session accordingly.

Web-Based ITS

Research and development in the area of Web-based ITS have a long tradition. First-wave Web-based ITS like ELM-ART [START_REF] Brusilovsky | ELM-ART: an Intelligent Tutoring System on the World Wide Web[END_REF] and PAT Online [START_REF] Ritter | PAT online: a model-tracing tutor on the World-Wide Web[END_REF], to name but a few, were followed by a number of other learning environments that used Web technology as means of delivering instruction. More recent Web-based ITS address other important issues, such as integration with standalone, external, domain-service Web systems [START_REF] Melis | ActiveMath: a generic and adaptive Web-based learning environment[END_REF], using standards and practices from international standardization bodies in designing Web-based learning environments [START_REF] Retalis | Modeling Web-based instructional systems[END_REF], and architectural design of systems for Web-based teaching and learning [START_REF] Alpert | Deploying intelligent tutors on the Web: an architecture and an example[END_REF][START_REF] Devedžić | Architectural patterns in pedagogical agents[END_REF][START_REF] Mitrović | Porting SQL-tutor to the Web[END_REF]. Rebai and de la Passardiere try to capture educational metadata for Web-based learning environments [START_REF] Rebai | Dynamic generation of an interface for the capture of educational metadata[END_REF].

An important line of research and study in Web-based ITS is that of pedagogical agents, autonomous software entities that support human learning by interacting with students/learners and authors/teachers and by collaborating with other similar agents, in the context of interactive learning environments [START_REF] Johnson | Animated pedagogical agents: face-to-face interaction in interactive learning environments[END_REF]. Pedagogical agents help very much in locating, browsing, selecting, arranging, integrating, and otherwise using educational material on the Web.

Ontological Support for WBE of Demography

In order to enable authoring of learning material to support intelligent teaching and learning of demography in the Web classroom through a Web-based ITS, it is necessary to provide a substrate of essential domain knowledge for the ITS to be based on. Likewise, it is also important to develop such educational content on the server in accordance with important pedagogical issues such as instructional design and human learning theories, to ensure educational justification of learning, assessment, and possible collaboration among the students. Moreover, the core of both the domain (demographic) and instructional (pedagogical) knowledge should be made available in machine-understandable and machine-processable form for different courseware in the Web classroom to reuse them.

Ontological Infrastructure

The way to provide all that is to develop a number of shareable and reusable ontologies, as machine representation of the core-knowledge infrastructure around which knowledge bases of a demographic Web-based ITS can be built. Each such an ontology should provide a set of knowledge terms, including the vocabulary, the semantic interconnections, and some simple rules of inference and logic for some particular topic or service [START_REF] Hendler | Agents and the semantic Web[END_REF]. Once a number domain and instructional ontologies are developed, the author of learning material can rely on them in developing, representing and structuring the body of knowledge in the courseware he/she creates. With an appropriate authoring tool, the learning material gets automatically annotated with pointers to a number of shareable domain (as well as instructional) ontologies.

There are many concepts in demography that are used in other disciplines as well (e.g., population growth and migrations are important in political sciences as well). Hence different domains can share some ontologies or parts of them, and sometimes complex ontologies can be composed of several simpler ontologies. In other words, ontologies can be stored on different servers on the Web, can point to each other, and can be reused by educational applications and different courseware, Fig. 2.

Interoperability and knowledge sharing between different educational applications can be achieved by using appropriate languages for representing ontologies and edu- cational content and services. Current trends in Web technology suggest that appropriate representation languages include XML, XML Schema, RDF, and RDF Schema languages, all developed under the auspices of WWW Consortium (http://www.w3.org/XML; http://www.w3.org/RDF). For developing domain ontologies, higher-level languages and graphical tools built on top of those four are a good choice.

Demographic Ontologies

For a demographic Web-based ITS, two kinds of ontologies are needed -demographic (domain) and pedagogical. We have developed some pedagogical ontologies according to the GET-BITS framework for building ITS [START_REF] Devedžić | The GET-BITS model of Intelligent Tutoring Systems[END_REF]. They are applicable in different Web-based ITS, and are beyond the scope of this paper. As for domain ontologies, we have started designing and developing them relying on domain knowledge represented in well-known textbooks such as [START_REF] Clarke | Population Geography[END_REF][START_REF] Pressat | Demographic Analysis: Methods, Results, Applications[END_REF] and [START_REF] Hinde | Demographic Methods[END_REF].

Fig. 3 represents a part of the knowledge structure pertaining to some well known concepts in demography, according to [START_REF] Clarke | Population Geography[END_REF]. We used it as the starting point for developing a set of demographic ontologies. Without going into more detailed explanations, it suffices to say that population composition denotes population structure based on the value or modality of a certain criterion. While the notion of the concepts from Fig. 3 is intuitively clear, it should be noted that other authors may have a different categorization.

Starting from these concepts and a number of other demographic concepts, their relationships and attributes, as well as from formulae needed to calculate various quantitative demographic indicators, we have designed and developed a set of demographic ontologies. We used the Protégé-2000 ontology development environment (http://protege.stanford.edu/). The following section presents details.

Design and Implementation

Fig. 4 a screenshot from Population composition ontology, one of the demographic ontologies that we developed using the knowledge structure from Fig. 3. In order to make our ontologies shareable and reusable, we converted them into RDF Schemata. Fig. 5 shows an example.

We have also developed ontologies related to population growth. Population growth depends on two components, natural increase (expressed in terms of fertility and mortality) and net migrations (i.e., immigration and emigration). A quantitative indicator showing the rate of population change is the population increase rate. Simple formulae are used to compute population increase rate and other quantitative indicators to initialize instances of the corresponding ontologies.

We are perfectly aware of the fact that our ontologies are not completed yet, neither individually, nor as an interrelated set of ontologies. It is now left to their users and domain experts to notify us of the usability and deficiencies of the ontologies we developed, and it is our responsibility to refine them in the future. As for the users, our intended users at the moment are Web courseware authors for our Web classroom. Indirectly, the students who are supposed to learn from the material the authors develop are also the users and potential critics of design of our ontologies. Once the design is refined to a satisfactory extent, we also hope for feedback from other institutions whose Web applications need demographic knowledge sharing and reuse, such as bureaus of statistics, electoral bodies, and other government organizations. Our demographic ontologies are parts of ongoing implementation of online teaching and learning material to be used in our Web classroom. Technical implementation details are presented in extenso in [START_REF] Šimić | Building an intelligent system using modern internet technologies[END_REF].

Related Work

The research in ontologies in general is already maturing, and so is the research in Webbased education. However, in the demographic research and education community the work on ontologies is only at its beginning. A notable exception is a research project in the Netherlands, aimed at finding a theoretically and methodologically correct definition and measurement for the population at risk and the birth rate in the demography of firms [START_REF] Brons | The "Birth Rate" in the Demography of Firms: an (Onto-) Logical Inquiry[END_REF]. It uses ontological analysis and symbolic logic as the main research tools to clarify these concepts.

Other relevant research includes certain categorizations and hierarchies of demographic concepts, important for building ontologies. Although there is no official standardized terminology and taxonomy of demographic concepts, such publicly available thesauri and hierarchies represent important starting points to both ontological research and standardization in this knowledge area. Examples include the thesaurus published by the French Committee for International Cooperation in National Research in Demography (CICRED, 2003) and the one published by The British Academy (British Academy, 2003). Interestingly, some of such online thesauri are published by multidisciplinary institutions and organizations, not only by demographers. For example, the National Institute on Alcohol Abuse and Alcoholism in USA has published an AOD Thesaurus: annotated hierarchy of concepts from demography and epidemiology (National Institute on Alcohol Abuse and Alcoholism, 2003). Other ontologically founded taxonomies and hierarchies of demographic concepts can be found in general-purpose knowledge servers, such as CYC (CYC Corporation, 2003).

Conclusions

Since the GET-BITS view of both pedagogical and domain ontologies is that they should evolve, we started with a small set of ontologies that represent widely known demographic concepts. Although they are not highly elaborated yet, they still provide at least a limited initial semantic interoperability across pedagogical agents, courseware, tools, and educational servers. If over time these ontologies prove to be really useful for developing demographic Web-based ITS, it makes sense to believe that they will get upgraded and extended over time. If, on the other hand, they fade away, it is highly likely that some other, competing ontologies in the domain of demography, possibly published elsewhere on the Web, will gain more attention and will become more widely used for developing courseware for our Web classroom.

Žiniatinkliu grindžiamas demografijos mokymo b ūdas

Mirjana DEVEDŽI Ć, Vladan DEVEDŽI Ć Šiame straipsnyje aptariamas žiniatinkliu pagr ist u švietimo technologij u taikymas universitetinio lygio demografijos dalyko mokyme. Paprastai studentai mokomi demografijos jiems skaitant paskaitas bei reikalaujant, kad studentai mokyt usi iš vadovėli u bei atlikt u demografini u skaičiavim u pratimus. Kai kurie studentai tok i mokymosi būd a laiko monotonišku bei sekinančiu, dėl to palaipsniui ima blėsti j u motyvacija mokytis. Modernios mokymo technologijos gali užkirsti keli a tokiai situacijai rastis, ar bent jau mažinti jos mastus. Žinoma, norint bet koki a technologij a naudoti mokymo ar mokymosi tikslais, pirmiausia reikia susipažinti su pagrindinėmis žiniomis apie j a. Šiame straipsnyje kaip tik ir kalbama apie pirmuosius pasiekimus kuriant toki a žiniatinkliu grindžiamo švietimo (WBE -Web Based Environment) infrastruktūr a demografijos srityje.

Tam, kad palaipsniui supažindintume su šio būdo teikiamomis galimybėmis mokant ir mokantis demografijos universitete, mes numatėme kelet a priemoni u. Pirmiausia, profesionali u kompiuterinink u komanda irengė žiniatinklio klas e, kurioje besimokantieji galėt u pasinaudoti esamomis žiniatinklio technologijomis tam, kad kuo lengviau isisavint u mokom aj a medžiag a. Pirmieji žiniatinklio klasėje vyk e praktiniai užsiėmimai, susij e su kit u mokom uj u dalyk u temomis, teikė daug vilči u. Antra, tam, kad paskatintume šitaip pertvarkyt a bei pritaikyt a asmeniniams poreikiams mokym asi, šioje klasėje idiegėme žiniatinklio technologijomis pagr istas intelektualaus mokymo sistemas. Galiausiai, tam, kad palengvintume mokomosios medžiagos pateikim a, suteiktume intelektin e param a mokymuisi bei galėtume pakartotinai naudoti mokymo išteklius, ėmėme kurti žiniatinkliu pagr ist a infrastruktūr a. Ši infrastruktūra remiasi daugeliu ontologij u, kuri u kiekviena pateikia tam tikras žini u išraiškas, tokias kaip žodynas, semantiniai ryšiai bei elementarios išvad u darymo ar loginio m astymo svarstant konkreči a tem a taisyklės.

Fig. 1 .

 1 Fig. 1. A Web classroom.

Fig. 2 .

 2 Fig. 2. Different Web-based ITS can share ontologies (O i -ontologies).

Fig. 3 .

 3 Fig. 3. Important concepts in demography.

Fig. 4 .

 4 Fig. 4. Creating Population composition ontology in Protégé-2000.

Fig. 5 .

 5 Fig. 5. The RDF Schema representation of the Population composition ontology.


Keywords: health information, internet, quality, terminology I

In France, there are thousands of information sites dedicated to health. Ranging from the simple popularisation of medical facts to institutional sites, including sites for associations of patients and professionals, sites freely available or requiring a free or paid-for access code, medical Net is growing fast. Ranking these information sources is difficult because most of these sites present several of the above characteristics. For example, many of the sites originally intended for healthcare professionals are easily viewed by the public, where scientific articles can be readily found but which cannot be exploited by the layperson. In order to reduce the problems linked to the quality of information found on the internet, the Health ON the Net (HON) Foundation established a quality charter, the Hon Code, for health sites. Moreover, in the medical field the terminology used by authors is complex and each database has its own thesaurus and its own terminology.

-Institutional sites:

*AMELI [19], WHO [20], HAS (French health authorities) [21], AFSSAPS [22], Pasteur Institute [23], etc *Pharmaceutical industry: the very powerful pharmaceutical industry lobby [24] -Bibliographic databases:

*Free access: dozens listed in the CISMEF [7] PubMed-Medline (the most used non-exhaustive, MesH little used by doctors) [25], Banque de Données de Santé Illustration of the diversity and heterogeneity in health information sources on Internet Pascal BADOR. Université de Lyon ; Université Lyon 1, équipe ELICO ; Faculté de Pharmacie, 8 avenue Rockefeller, F69737 Lyon cedex 08, France ; pascal.bador@univ-lyon1.fr T Publique [26], Toxibase [27], Nosobase [28], Pharmadoc [29], etc Access to a number of scientific journal articles freely available to the public *Access fee: Embase-Elsevier (European Medline), Pascal, International Pharmaceutical Abstracts, Cochrane, Web of Sciences, ScienceDirect-Elsevier, accessible to researchers from universities and research organizations.

Ultimately, there are RISKS: *For the public: many heterogeneous information sources, uneven in quality, not always up to date and mostly accessible free of charge, hence a significant risk of persons seeking information about their health, but without the ability to discriminate.

*For health professionals (and therefore patients): little training in documentary research (no systematic exhaustive search, poorly developed search strategies, lack of critical thinking on the origin of the information and the aim of the author, which may present a conflict of (pharmaceutical industry) interest)..

II. A CODE OF CONDUCT: THE HONCODE OF THE HEALTH ON THE NET FOUNDATION [9]

The Health On the Net Foundation is the leading organization promoting and providing online information about health and drugs, as well as their appropriate and effective use. Founded in 1995, HON is a non-governmental, non-profit making organization, accredited by the United Nations Economic and Social Council. For twelve years, HON has focused on one key issue, providing health information to citizens, information that respects their code of ethics. To cope with the amount of health information available online, the HON Code of conduct provides a varied consensus on the standards to protect citizens from misleading health information Figure 1: a joke on the quality of health information on the Internet by HON The HONcode is a quality charter developed by the Health On the Net Foundation and adopted in France by the Health Authorities in 2007. It addresses the public demand for a site webmaster for medical health. Created in 1995, it has continued to grow to become the most widely used and most popular ethical code for health websites: A health site with the HONcode "label" has the following logo on its homepage : The HONcode addresses one of the key issues on the Internet: reliability and credibility of the medical and health information. HONcode certification is free of charge. The certification conducted by HON involves a thorough evaluation of the websites, based on application of the HONcode. There is ongoing monitoring throughout the year and a systematic annual review of HONcode certified sites.

The HONcode is not a system that rewards sites. The fact that the site is not certified does not mean that it is of poor quality.

The HONcode -Eight quality criteria:

A. Authoritative

Indicate the qualifications of the authors Any medical or health advice provided and hosted on this site will only be given by medically trained and qualified professionals unless a clear statement is made that a piece of advice offered is from a non-medically qualified individual or organisation.

B. Complementarity

Information should support, not replace, the doctor-patient relationship. The information provided on this site is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her existing physician.

C. Privacy

Respect the privacy and confidentiality of personal data submitted to the site by the visitor. Confidentiality of data relating to individual patients and visitors to a medical/health Web site, including their identity, is respected by this Web site. The Web site owners undertake to honour or exceed the legal requirements of medical/health information privacy that apply in the country and state where the Web site and mirror sites are located.

D. Attribution

Cite the source(s) of published information, date and medical and health pages.

Where appropriate, information contained on this site will be supported by clear references to source data and, where possible, have specific HTML links to that data. The date when a clinical page was last modified will be clearly displayed (e.g. at the bottom of the page).

E. Justifiability

Site must back up claims relating to benefits and performance. Any claims relating to the benefits/performance of a specific treatment, commercial product or service will be supported by appropriate, balanced evidence in the manner outlined above in Principle 4.

F. Transparency

Accessible presentation, accurate email contact. The designers of this Web site will seek to provide information in the clearest possible manner and provide contact addresses for visitors that seek further information or support. The Webmaster will display his/her E-mail address clearly throughout the Web site.

G. Financial disclosure

Identify funding sources Support for this Web site will be clearly identified, including the identities of commercial and non-commercial organisations that have contributed funding, services or material for the site.

H. Advertising policy

Clearly distinguish advertising from editorial content. If advertising is a source of funding it will be clearly stated. A brief description of the advertising policy adopted by the Web site owners will be displayed on the site. Advertising and other promotional material will be presented to viewers in a manner and context that facilitates differentiation between it and the original material created by the institution operating the site.

Another way to illustrate the heterogeneity of health information on the Internet and its difficulty of access can be achieved by comparing the different thesaurus databases

III. HETEROGENEITY OF TERMINOLOGY USED BY THE DOCUMENTATION TOOLS

In the medical field, the terminology used by authors is complex, superfluous and not very standardized, hence creating difficulties in documentary research:

-Synonyms: beta-blocking agent, beta-blocker, betaadrenergic, beta-inhibitor -In writing: betablocking agent, betablocker, beta adrenergic, beta inhibitor β-blocking agent, β-blocker, β-adrenergic, β-inhibitor So, fairly elaborate thesauri have been developed for the databases. However, these still remain complex to use by researchers seeking specific information. Furthermore, each database has its own thesaurus and its own terminology.

I present here an illustration using the term "ANTIBIOTIQUE".

*MeSH for Medline, also used by CISMEF in its French version: *Emtree for Embase (Elsevier), paid access, not available: *The Toxibase thesaurus:

ANTIBACTERIAL ANTIBIOTIC

This examples of heterogeneous terminologies used by different databases can explain the difficulties to find health information in databases. One solution could be that each health database take systematically the Mesh thesaurus and adapt it to its microfield if necessary.

IV. CONCLUSION

Through these few examples, it should be clear to everyone that the diversity and variety of documentary sources, and the lack of standardization of terminology in the field of health, pose a major problem for access to reliable, comprehensive information taking into account the latest scientific advances. Whether it is the general public, professionals of information or health, all benefit greatly from the pooling of documentation tools and procedures. This would undoubtedly provide better access to health information, and thus better support for the health of every sick person.

Figure 2 :

 2 Figure 2: the HON Code "label"

Figure 3 :

 3 Figure 3: example of vocabulary of MesSH used by CISMEF in French.

Figure 5 :

 5 Figure 5: example of vocabulary of Toxibase

Table 1 :

 1 information given by Elsevier

	Emtree	Mesh	Emtree value (for the
			user)
	"Natural	Has many	Intuitive and recognizable
	language	"inverted	terms for ease of use
	terminology"	terms" (e.g.
	(e.g.myeloid	leukemia,
	leukemia)	myeloid)
	Has more than	Has far	High probability that term
	230,000	fewer	used by user is in Emtree
	synonyms	synonyms
	(incl. over	(exact
	144,000 drug	number
	synonyms)	unknown)
	Includes all		Emtree can easily be used
	MeSH terms		by MeSH users
	(many as
	synonyms)
	Relies upon	Has many	No dependence on or need
	"meaning"	scope notes	to look up scope notes
	invested in	to describe
	terms by	how terms
	authors using	are used
	them
	Larger (over	Smaller (ca.	Best chance of finding both
	56,000	24,000	drug and non-drug
	preferred	preferred	terminology
	terms)	terms)
	*The BDSP thesaurus: