Pavol Prokop

Andrea Tolarovičová

Anne M Camerik

Viera Peterková

Keywords: attitudes, biology education, ecology education, student user): spiders, cross-cultural comparison

High school students' attitudes towards spiders: A cross-cultural comparison

Human attitudes towards and fear of animals are determined by cultural and evolutionary factors [START_REF] Herzog | Attitudes towards animals: origins and diversity[END_REF][START_REF] Fredrikson | Parental history, aversive exposure and the development of snake and spider phobia in women[END_REF][START_REF] Davey | A cross -national study of animal fears[END_REF]. In the school age group of 6 -16 years children's attitudes develop through affective, cognitive and ecological stages [START_REF] Kellert | Attitudes towards animals: Age-related development among children[END_REF][START_REF] Field | Conditioning models of childhood anxiety[END_REF]. Considering that the main attributes of scientific literacy include the development of both knowledge (especially conceptual and procedural) and attitudes [START_REF] Jenkins | Scientific literacy and school science education[END_REF], it is important to influence students' attitudes positively towards animals. The more they know about animals and their environment the better they will be able to help save the earth's biodiversity.

Humankind is mainly attracted to large mammals like dolphins [START_REF] Barney | Assessing knowledge, attitudes and behavior towards charismatic megafauna: The case of dolphins[END_REF], pandas [START_REF] Bexell | Observing Panda play: implications for Zoo programming and conservation efforts[END_REF] and elephants [START_REF] Swanagan | Factors influencing zoo visitors' conservation attitudes and behavior[END_REF]. The relationship between humans and less popular animals like large carnivores [START_REF] Røskaft | Patterns of self-reported fear towards large carnivores among the Norwegian public[END_REF], and sharks (Thompson & Mintzes, 2002) is, however, still poorly understood.

Even less is known about human attitudes towards invertebrates. Both adults and children tend to avoid invertebrates because they are behaviourally and morphologically unfamiliar (Wilson, 1987;[START_REF] Kellert | Values and perceptions of invertebrates[END_REF]. This is surprising since this group of animals has become of increasing value in the pharmaceutical industry [START_REF] Nicholson | Spiders of medical importance in Asia-Pacific: Atracotoxin, latrotoxin and related spider neurotoxins[END_REF] and in agriculture [START_REF] Nyffeler | Evaluation of the importance of the striped lynx spider, Oxyopes salticus (Araneae, Oxyopidae), as a predator in Texas cotton[END_REF][START_REF] Kellert | Values and perceptions of invertebrates[END_REF]. The appearance of invertebrates in ecological programmes on television often evokes anxiety in viewers. This anxiety correlates negatively with people's attitudes towards invertebrates and thus with their level of interest to know more about them [START_REF] Randler | Cognitive and emotional evaluation of an amphibian conservation program for elementary school students[END_REF]. Invertebrates are easy to observe and handle and could provide good subjects for the study of different types of lifecycles. However, the use of these animals has been little explored in science classes. Spider phobia is one of most common animal phobias in Western society [START_REF] Kirkpatrick | Age, gender and patterns of common intense fears among adults[END_REF][START_REF] Fredrikson | Gender and ge differences in the prevalence of specific fears and phobias[END_REF][START_REF] Muris | Common childhood fears and their origins[END_REF]. This fear is attributed either to genetic, social and cultural differences, or personal experiences [START_REF] Fredrikson | Parental history, aversive exposure and the development of snake and spider phobia in women[END_REF]. [START_REF] Seligman | On the generality of the laws of learning[END_REF][START_REF] Seligman | Phobias and preparedness[END_REF] first introduced a hypothesis of biological preparedness to explain why people dislike spiders and snakes more than other animals. [START_REF] Seligman | On the generality of the laws of learning[END_REF] proposes that these animals presented a critical danger to our ancestors, hence predisposing them to rapid learning processes. For example, quick reactions to snake-induced stimuli were evolutionarily selected for [START_REF] Öhman | On the unconscious subcortical origin of human fear[END_REF]. [START_REF] Davey | The "disgusting" spider: the role of disease and illness in the perpetuation of fear of spiders[END_REF] and [START_REF] Davey | A cross -national study of animal fears[END_REF], however, argue that fear of spiders has a cultural rather than evolutionary background. They found that fear of spiders covaries with disgustsensitivity. This means that spiders are viewed in the same category as cockroaches, snails, wasps and other, non-predatory, but "disgusting" animals [START_REF] Davey | A cross -national study of animal fears[END_REF]. Although the link between spiders and disgusting animals is puzzling at first glance, they propose that spiders in the Middle Ages were associated with illness, e.g. the plague [START_REF] Davey | The "disgusting" spider: the role of disease and illness in the perpetuation of fear of spiders[END_REF].

Attitudes towards spiders

Spiders, then, were seen as harbingers of plague and death. [START_REF] Davey | The "disgusting" spider: the role of disease and illness in the perpetuation of fear of spiders[END_REF] mentions that, according to [START_REF] Renner | Spinnen: Ungeheuer sympathisch[END_REF], this association was used as the basis for Jeremias Gotthelf's famous story "The Black Spider", published in 1842. Although [START_REF] Davey | The "disgusting" spider: the role of disease and illness in the perpetuation of fear of spiders[END_REF] 'disease

avoidance' hypothesis still has to be supported, he predicts that Europeans should be more fearful of spiders than, for example, some African tribes. In the same study [START_REF] Davey | The "disgusting" spider: the role of disease and illness in the perpetuation of fear of spiders[END_REF] again cites [START_REF] Renner | Spinnen: Ungeheuer sympathisch[END_REF] who mentions that in some African cultures the spider is revered as a wise creature and its nests are cleaned and protected by the local people. He expects that some African cultures will have a more positive attitude towards spiders than European cultures. In a later study [START_REF] Davey | A cross -national study of animal fears[END_REF] conducted a cross-cultural comparison of animal fears, including fear of spiders. A sample from Africa was, however, not included. On the other hand, the 'biological preparedness' hypothesis [START_REF] Seligman | On the generality of the laws of learning[END_REF] could predict a greater fear of spiders in South Africa than in Europe since several South African spiders possess venoms that are dangerous to humans (e.g. [START_REF] Dippenaar-Schoeman | Afričan spiders, an identification manual[END_REF]Vetter & Visscher, 1998). In Europe there are no such venomous spiders.

Although children are excellent models for testing both evolutionary predispositions to avoid unpopular animals like spiders, and the effects of education strategies which would help to eliminate fear of spiders, systematic spider attitude surveys among school age children are rare. As far as we are aware, only Prokop and Tunnicliffe (2008) have examined attitudes towards spiders in three attitude dimensions (ecoscientistic, negativistic and naturalistic) as well as knowledge of these animals and myths about them. Their sample comprised 196 children aged 10 -16 years. Other research on school children has been mainly focused on fears and phobias [START_REF] Muris | Common childhood fears and their origins[END_REF]. Prokop and Tunnicliffe (2008) found that children's attitudes towards spiders were rather negative (although less negative in boys than in girls), and the mean attitude score decreased as their age increased. Importantly, a substantial number of children believe in myths about spiders. For example, only one third (28 %) of all children in their research was aware that the bite of the tarantula is not fatal to humans. Again, a majority of children (62 %) incorrectly believed, or were undecided about, the myth spiders are dangerous to humankind particularly when they are asleep. Belief in these stories correlated with the negativistic dimension, meaning that the stronger the belief the higher the score of negative attitudes towards spiders. Their research suggests that children's views of spiders need to be improved.

Gender differences in attitudes towards spiders

A number of studies were conducted on participants of primary school age [START_REF] Kindt | Spider phobia questionnaire for children (SPQ-C): A psychometric study and normative data[END_REF][START_REF] Muris | Common childhood fears and their origins[END_REF]Prokop & Tunnicliffe, 2008) et al., 1996;[START_REF] Gerdes | Spiders are special: fear and disgust evoked by pictures of arthropods[END_REF] report that males are less fearful of spiders than females. To date, however, very little is known about the origin of this gender difference.

According to the ''environment of evolutionary adaptedness'' hypothesis [START_REF] Hawkes | Hunting income patterns among the Hadza: big game, common goods, foraging goals and the evolution of the human diet[END_REF], men were hunters and therefore had to deal directly with many dangerous animals and engaged in greater risk-taking activities than females [START_REF] Byrnes | Gender differences in risk-taking: A metaanalysis[END_REF]. Women, on the other hand, probably stayed in the close vicinity of their camps because their parental duty was to raise and care for their children. Thus, women more easily developed fear towards animals that posed a threat [START_REF] Røskaft | Patterns of self-reported fear towards large carnivores among the Norwegian public[END_REF]. [START_REF] Muris | The role of parental fearfulness and modeling in children's fear[END_REF], posing the question why fear of spiders is more common among girls than among boys between 9 and 13 years, found that conditioning experiences play a most important role. Fredriksson et al. (1996) suggest that gender differences in animal phobias may reflect different genetic and/or social transmission patterns. The authors speculate that social transmission of fears and phobias is probably more frequent among women than men.

Žoldošová and Prokop (2006), researching the effect of a five-day field trip on cannibalism in spiders on primary school children (10 -14 years), noticed that the fieldwork generated an increased interest in the topic among the participants. Before the field trip boys were more interested than girls in cannibalism, but gender differences disappeared after the experience.

The researchers linked this to the discussions and practical activities with spiders during their field trip. The control group, who did not participate in the field trip, had significantly lower interest in the subject. Unfortunately, these authors failed to control for possible changes in fear of spiders. Environmentally literate citizens have a certain level of knowledge and relevant attitudes and display pro-environmental behaviour [START_REF] Roth | Environmental Literacy: Its Roots, Evolution, and Directions in the[END_REF]. Attitudes correlate with behaviour [START_REF] Kraus | Attitudes and the prediction of behaviour: a meta-analysis of the empirical literature[END_REF], and several researchers found a link between attitude and knowledge [START_REF] Cohen | Environmental information versus environmental attitudes[END_REF][START_REF] Hsu | An assessment of environmental knowledge and attitudes held by community leaders in the Hualien area of Taiwan[END_REF][START_REF] Kaiser | Environmental attitude and ecological behaviour[END_REF]Thompson & Mintzes, 2002;[START_REF] Prokop | Slovakian pupils' knowledge of and attitudes toward birds[END_REF][START_REF] Prokop | Vampires are still alive: Slovakian student's attitudes toward bats[END_REF]. Considering these arguments with the historically greatly emphasised link between science education and the learning capacity of students [START_REF] Alsop | Science education and affect[END_REF], one expected that acquiring knowledge or developing a greater awareness of one's environment would result in positive changes in attitude [START_REF] Morgan | Predicting effectiveness of wildlife education programs: A study of students' attitudes and knowledge towards snakes[END_REF][START_REF] Kellert | Values and perceptions of invertebrates[END_REF]. However, conflicting results in several studies do not support the link between attitude and knowledge. For example, [START_REF] Brossard | Scientific knowledge and attitude change: The impact of a citizen science project[END_REF] investigated the effects of an informal science education project (The Birdhouse Network) on the participants' knowledge of birds, and their attitudes towards science and the environment. They found that participants' knowledge of birds increased in terms of basic facts about the biology of birds. However, they did not find any statistically significant change in participants' attitudes towards science and the environment.

Can science education improve attitudes towards spiders?

Similarly, [START_REF] Kuhlemeier | Environmental knowledge, attitudes and behavior in Dutch secondary education[END_REF] and [START_REF] Makki | Lebanese secondary school students" environmental knowledge and attitudes[END_REF] found only moderate correlations between knowledge of and attitude towards the environment.

In the same sample of participants Prokop and Tunnicliffe (2008) found a significant correlation between knowledge of and attitudes towards bats, but not towards spiders. These authors hypothesize that a weak link between these qualities could be expected when there was a conflict between self-awareness and the evolutionary predisposition to avoid a particular animal. Their findings support the hypothesis, as the self-perceived danger was lower for bats (where the correlation was found) than for spiders. In a recent study [START_REF] Muris | A dirty animal is a scary animal! Effects of disgust-related information on fear beliefs in children[END_REF] investigated whether disgustrelated information has an impact on the fear beliefs about Australian marsupials (unknown to the research sample) in children aged 9 -13 years. Their results indicate that disgust-related information did not only produce higher levels of disgust but also increased the children's fear beliefs about these animals. Conversely, cleanliness-related information decreased levels of disgust and yielded lower levels of fear.

These findings suggest that knowledge about certain animals could improve attitudes towards them. However, less popular animals that are as important in nature as the more popular ones are perceived somewhat differently and require a more educated approach (Prokop & Tunnicliffe, submitted). For example, [START_REF] Morgan | Predicting effectiveness of wildlife education programs: A study of students' attitudes and knowledge towards snakes[END_REF] reported that increased knowledge of snakes (controversial animals) alone failed to improve children's attitudes towards them. However, when children experienced physical contact with snakes, as well as an informal presentation about the biology of snakes, their attitudes changed positively.

Similarly, Žoldošová and Prokop (2006) found that actual observations of sexual cannibalism in spiders during informal field trips increased children's interest in that behaviour.

Science education in South Africa and Slovakia

Slovakia and South Africa are geographically, ethnically and culturally very distinct countries.

Not surprisingly, science education approaches in these countries, at least in elementary schools and high schools, are different. Thus, in the next section, we provide a brief overview of the main differences in science education strategies.

In South Africa the central government provides a national framework for school policy, but administrative responsibility lies with the provinces. Power is further devolved to grass-roots level via elected school governing bodies, which have a significant say in the running of their South Africa and Slovakia, the educational system seems to be a significant factor that can potentially influence attitudes towards animals.

Purpose

This study examines cross-cultural differences in students' attitudes towards spiders. We compare two culturally distinct countries, South Africa and Slovakia (Europe), because the risk of being bitten by spiders is different in each country. There are about 6,000 spider species in Africa, and at least 2,000 in South Africa (Dippenaar-Schoeman & Jocqué, 1997), but only about 1,000 species in Slovakia [START_REF] Gajdoš | Katalóg pavúkov Slovenska. Ústav krajinnej ekológie SAV[END_REF]. Several spiders in South Africa pose the risk of serious injury (e.g. the black and brown button spiders of genus Latrodectus, the violin spider (Loxoseeles sp.), the sac spider (Cheiracanthium sp.) and the six-eyed sand spider (Sicarius sp.) [START_REF] Dippenaar-Schoeman | Afričan spiders, an identification manual[END_REF]Vetter & Visscher, 1998). In contrast, there are no reports from Slovakia of spiders that are dangerous to humans. Our specific intention was to investigate whether living in countries with different risk levels of being bitten by spiders influences the students' attitudes towards them. Prokop and Tunnicliffe (2008) speculate that the risk of being threatened by animals should break the link between attitudes and knowledge. Living in an area with a higher risk of threat should be associated with low correlation between attitudes and knowledge. Our aim is to understand the links between attitude and knowledge. This could provide useful information for science education as it is not yet known whether teaching strategies should consider taking this risk factor into account. Again, because former research was focused mainly on spider phobia, it is This paper explores the following questions: (1) Is there any difference in knowledge of and attitude towards spiders between Slovakian and South African high school students? (2) Are there any differences in attitude towards spiders with respect to gender? (3) Is there any link between attitude towards and knowledge of spiders among Slovakian and South African high school students?

High school students were chosen because students aged between 13 -18 years appear to be the most appropriate targets to foster ethical and ecological understanding of the role of animals in nature [START_REF] Kellert | Attitudes towards animals: Age-related development among children[END_REF]. It appears that the level of sensitivity for the environment in an adult is formed during the teenage years [START_REF] Sivek | Environmental sensitivity among Wisconsin high school students[END_REF]. Therefore high school students represent the most appropriate age group for environmental education, because they are capable of understanding complex situations in the environment [START_REF] Dienno | High school students' knowledge, attitudes, and levels of enjoyment of an environmental education unit on nonnative plants[END_REF].

Methods

Construction of the Spider Attitude Questionnaire (SAQ)

Students' attitudes towards and knowledge of spiders were measured by 5 -point Likert-type items adapted from a questionnaire published elsewhere (the Spider Attitude Questionnaire,

Prokop & Tunnicliffe, 2008; Appendix A). Items were developed in a similar way to [START_REF] Kellert | The Value of Life: Biological Diversity and Human Society[END_REF] attitude scale towards animals. Most of the negativistic items were derived and modified following the Spider Phobia Questionnaire [START_REF] Kindt | Spider phobia questionnaire for children (SPQ-C): A psychometric study and normative data[END_REF]. Knowledge of spiders was measured by items that represent basic facts about their biology. Attitude items were prepared following questionnaires published in similar studies (e.g. [START_REF] Barney | Assessing knowledge, attitudes and behavior towards charismatic megafauna: The case of dolphins[END_REF]. The negativistic dimension is designed specifically to measure active avoidance of spiders as a result of dislike or fear. The scientistic dimension measures interest in the biology of spiders and the gathering of information about them. The ecologistic dimension investigates the participants' concern for the role of spiders in nature and the way in which humans and spiders interact. The naturalistic dimension gauges interest in direct contact with spiders and how one reacts when one encounters them in nature.

The original, self-constructed questionnaire consists of 24 attitude items and 10 knowledge items. They are scored from 1 (strongly disagree) to 5 (strongly agree). Items are formulated either negatively or positively (Oppenheim, 1999). Negative items are scored in the reverse second factor. In agreement with these suggestions, the scientistic dimension explained 36.6 % of total variance, the negativistic dimension explained 10.1 %, the naturalistic dimension 5.1%, and the ecologistic dimension 4.4 % of total variance.

Finally, we measured the reliability of all remaining items. The Cronbach's alpha coefficient for the whole instrument (0.92) indicates that the questionnaire is highly reliable [START_REF] Nunnaly | Psychometric theory[END_REF]. In addition, the same reliability test [START_REF] Nunnaly | Psychometric theory[END_REF] applied to each separate dimension allows us to accept all dimensions. The inter-item correlations of attitude items ranged between 0.14 and 0.41.

The Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy (the index for comparing the magnitude of the observed correlation coefficients to that of the partial correlation coefficients) is 0.95, which allows us to apply factor analysis. Bartlett's test of sphericity is used to test the null hypothesis that variables in the population correlation matrix are uncorrelated. The observed significance level is high (χ 2 = 7820.57, df = 276, p < .001). It is concluded that the strength of the relationship among variables was strong [START_REF] George | SPSS for windows; Step by step[END_REF]. These indicators thus allowed us to use factor analysis for the data.

Participants

The Because the male-female ratio was skewed in the sample from South Africa, the power of statistical difference between males and females was additionally analysed by calculating the effect size measure (Cohen's d) for groups [START_REF] Cohen | Statistical Power Analysis for the Behavioral Sciences[END_REF], because it is independent of sample size. The measure is calculated as the difference between two means, divided by the standard deviation of either group. [START_REF] Cohen | Statistical Power Analysis for the Behavioral Sciences[END_REF] offered the following guidelines for interpreting effect sizes: d = 0.20-small effect; d = 0.50-medium effect; d = 0.80-large effect. In common sense terms, a d of 0.20 may be statistically significant but the difference is not apparent to the casual observer, a d of 0.50 is noticeable to the average person, and a d of 0.80 or higher is quite obvious [START_REF] Lippa | Gender, Nature, and Nurture[END_REF].

The educational system in South Africa is still very much in transition. A new system was introduced after the democratic elections in 1994 and the levels of education in the participating schools are still very much coloured by the former apartheid-era school system.

All schools in the new system should theoretically be mixed-race schools, but schools in traditionally black areas (urban as well as rural) are often attended only by children from black families. Schools from traditionally white areas have since 1994 accepted children from

all other race groups. Many teachers of all races, but especially in the traditionally black schools, still struggle to apply the new curriculum. In these schools English, mathematics and science were often poorly taught or understood in the past, and this is still the case in many instances today either because teachers themselves do not know enough English or have an inadequate understanding of mathematics and science, or the foundation of these subjects among the children is poor.

The schools participating in the Spider Attitude Questionnaire (SAQ) were selected to represent the diversity of backgrounds of a population sample of the pre-1994 period. The ratio of coloured and black to white children is 50:50. Brescia House School, situated in an affluent area, is a single-sex school (girls-only) and traditionally white, but since 1994 it has also admitted children from black families (98% white, 2% black).

All four Slovakian schools were typical state high schools with enrolments of between 300 -600 students. Two of them were also Catholic schools so that differences in the selection of samples between the two countries were minimised. The third was a grammar school and the fourth a health school. There are no obvious differences in socioeconomic status (because these schools are not private) or race (all students were Caucasian) between students in the participating schools in Slovakia.

Although we were originally interested in differences in attitude towards spiders among all participating schools, or at least between Catholic and government schools, these differences which are presented in All questionnaires were personally administered by the same researcher (A.T.) in both countries. Before administration South African teachers were consulted about the appropriateness of language of the SAQ and changes were made accordingly. In Slovakia, the wording of items and their appropriateness was maintained from previous research (Prokop & Tunnicliffe, 2008).

Results

Students' knowledge of spiders

A two -way ANOVA showed that there is a significant effect of country (F 1,732 = 9.03, p < .01, η 2 = .01) on the students' knowledge of spiders, but gender differences remained nonsignificant (F 1,732 = 3.01, p = .08, η 2 = .004). The interaction between country × gender was again not significant (F 1,732 = 1.88, p = .17, η 2 = .003). The effect of country showed that Slovakian students had a better knowledge of spiders (M = 33.73, SE = .23) compared to the South African students (M = 32.31, SE = .29). However, the η 2 for the effect of country explains only 1.0 % of the total variance of the knowledge score which means that this difference is very insignificant. The effect of gender was much lower (see above). Cohen's d values for gender differences corroborate previous findings. To summarize, values obtained from calculating all combinations (males vs. females from two countries), showed that South African males tend to have a lower knowledge score than Slovakian males (d = 0.49) and females (d = 0.54) (medium size effects). Effect sizes for other combinations did not exceed a value of 0.22 (small effect).

Most students correctly identified the number of legs a spider has (70 % were correct). About a third (29 %) of all participants answered that sexual cannibalism is not widespread among than the Slovakian students (M = 3.30, SE = .07) (t = 7.23, df = 734, p < .001). About a third (35 %) knew that spiders do not belong to the insects. Little is known about the feeding habits of spiders; only 40 % agreed that spiders usually catch smaller animals. There seems to be no knowledge of maternal care for spiderlings, since only 32 % knew that some female spiders carry their young on their backs. Interestingly, this was the only item that was answered significantly better by South African students (M = 3.34, SE = .06), than Slovakian students (M = 3.17, SE = .05) (t = -2.63, df = 734, p = .009). About the same percentage (37 %) knew that orb-weaving behaviour is genetically fixed. Slovakians answered this item better (M = 3.46, SE =.06) than the South Africans (M = 3.2, SE = .08) (t = 4.30, df = 734, p < .001). The best answered questions were those about the overwintering of spiders (55 %) and orb-web adhesiveness (69 %).

Attitudes to spiders

The histogram (Fig. 1) of the Likert scale shows that negative/neutral responses (scores 1 -3) are more prevalent than positive responses (scores 4 and 5). This suggests that at least 30 % of all participants are afraid of spiders. Two-way multivariate analysis of variance (MANOVA) with gender and country as factors and residual values from four attitude dimensions as dependent variables was performed. Attitudes to spiders are mainly influenced by gender (Wilk's λ = 0.86, F 4,729 = 29.82, p < .001, η 2 = 0.14), followed by country (Wilk's λ = .95, F 4,729 = 10.02, p < .001, η 2 = .05) and interaction between these variables (Wilk's λ = .95, F 4,729 = 8.91, p < .001, η 2 = .05). The latter result refers only to the higher score of South African male and female students rather than to different gender-related patterns between countries.

Insert

In both countries, males score higher in the negative attitudes towards spiders in each dimension compared with females (Fig. 2). Univariate analysis of gender differences is significant at level p < .001. All Cohen's d values calculated for means derived from each dimension fully corroborate these differences. All d's ranged between 0.47 -1.08 which means that these differences are of medium-large statistical power. This indicates that males generally have a more positive attitude towards spiders than females.

Insert Fig. 2 here

There is no significant difference between the scores of either country with regard to the negativistic dimension (F 1,732 = .61, p = .43) which means that the South African students

were not more fearful of spiders than the Slovakian students.

South African students scored higher in the naturalistic, scientistic and ecologistic dimensions (F 1,732 = 6.71, 36.16 and 7.62, respectively, all p < .01 and less) meaning that they were more interested in the biology of spiders, and in direct contact with them and were aware of their importance in nature.

Although previous analyses were controlled for some potentially confounding factors, we performed additional analysis, to avoid misinterpretation of results.

The scientistic dimension

Students scored higher than 50 % in only two of the seven items of the scientistic dimension, which means that spiders were not perceived very positively in this dimension. Little more than half of the students would like to know how scientists investigate spiders (55 %) and asked for more information about large tropical spiders (52 %). About 44 % wanted to know how spiders build their webs. About one-third is attracted to reading a book (39 %) or watching a natural history film (37 %) about spiders. The same percentage (30 %) would like either to participate in an expedition to investigate spiders or to learn more about spiders in school. In summary, spiders appear to be interesting animals for a significant number of students. About one-third of the children showed negative attitudes towards spiders. For example, 28 % agreed that even the thought of touching a spider scared them, or would not be able to sleep when there was a spider in the window (35 %). Nearly half of them (47 %) agreed that they become nervous when they know that a spider is somewhere close to them, or that they will run from a room which has a spider in it (41 %). A third (36 %) did not like pictures of spiders, while a similar number (32 %) claimed that spiders scared them more than other animals and that they did not want to catch a spider even if they were wearing gloves. This means that about one-third of children show a strong aversion to spiders.

The negativistic dimension

The naturalistic dimension

Only 13 % of all students would be agreeable to camping near a river where spiders were found or would like to have spiders under their roof. The majority of students (69 %) preferred to live in a country with fewer spiders. A similar number of students (64 %) did not want to catch a spider with bare hands. About half (49 %) would not like to go to places where spiders were found and disagreed that capturing spiders was an exciting activity (56 %).

In conclusion, the naturalistic dimension underscored the negative attitudes of students towards spiders. Most of the students did not want to be in physical contact with spiders.

The ecologistic dimension

Within this dimension the most positive attitude is reflected in the observation of web building behaviour (41 %). The protection of spiders (35 %), students' sympathies towards spiders (23 %) and reduction in the use of chemicals to increase a spider population in the vicinity of humans (22 %) were viewed positively by only a minority of students. This suggests that students have either limited information about the role of spiders in the

The relationship between knowledge of and attitudes towards spiders

In the subsequent analyses, dependent variables (knowledge or attitudes) were controlled for the effect of gender and school by calculating residuals from regression analysis. After comparing the attitude and knowledge scores of each country separately, there is a low, although statistically significant correlation between knowledge and attitudes in Slovakia, but very weak correlation in South Africa (Fig. 4,5). To examine the relationship between attitudes towards and knowledge of spiders, multiple regression (forward stepwise method) was performed. In this analysis, four dimensions of students' attitudes towards spiders were chosen as predictor variables. Knowledge of spiders was defined as a dependent variable. In

Discussion

This study compares the attitudes of high school students towards and knowledge of spiders in South Africa and Slovakia.

The distribution of the overall mean scores suggests that these attitudes are generally rather neutral/negative. Compared with males, female students generally score lower in all four dimensions. Correlation between knowledge of and attitudes towards spiders is generally low, but this association is stronger among Slovakian than South African students. Knowledge of spiders shows the highest correlation with scientistic attitudes in Slovakian students, and with ecologistic attitudes in South African students. South African students have a similar level of fear of spiders as Slovakian students, but they score higher in the scientistic, naturalistic and ecologistic attitudes.

Effect of culture, evolution or science education strategies?

Our results reveal significant differences in attitude towards spiders among high school students in the two countries, which might be linked to cultural rather than evolutionary origins. South Africa and Slovakia also have different science education strategies. For this reason it is possible that the differences in attitude are the products of both cultural background and science education. However, our results do not allow us to draw any conclusions with regard to this issue. We would therefore rather discuss how these three mechanisms, evolutionary differences, cultural background, and education have an impact on the students' attitudes.

How can evolutionary or cultural differences account for these dissimilarities in attitudes towards spiders? Our results do not support the 'disease avoidance' hypothesis which postulates that because of historical events (Great Plagues in the Middle Ages, [START_REF] Davey | The "disgusting" spider: the role of disease and illness in the perpetuation of fear of spiders[END_REF], fear of spiders is greater among Europeans than people of African descent. This is in Considering that the sample of participants in this analysis consisted from only indigenous Africans, these results suggest that South African peoples have greater fear of spiders than Slovakian peoples supporting the biological preparedness hypothesis [START_REF] Seligman | Phobias and preparedness[END_REF]. Further research in this area is needed.

The revised national curriculum for science education in South Africa does not prescribe that students are required to learn anything about spiders and is not as restrictive as the Slovakian curriculum. In South Africa students learn about the biology of animals and their differences.

South African teachers have more opportunities to choose between topics that they consider of interest and value to their students. It is therefore possible that South African teaching strategies are more supportive of student's interest in animals than the corresponding Slovakian strategies. This could explain why the level of knowledge of spiders in South

African students has no bearing on their interest in the animals (Fig. 4). In contrast, Slovakian teachers have to adhere rigorously to strict teaching plans. Slovakian children first learn to compare spiders with insects. Later they learn systematic zoology where the emphasis is on exact knowledge of spiders.

Significance of gender

As in several other studies (e.g., [START_REF] Gerdes | Spiders are special: fear and disgust evoked by pictures of arthropods[END_REF], we found that fear of spiders is greater in females than in males. Compared with males, females scored lower in all four attitude dimensions. This suggests that males have not only less fear of spiders, but also a greater interest in them. It is questionable whether less interest in spiders in females is associated with the fact that they are less interested in wild animals in general (Lindemann-Matthies, 2005), or whether fear of spiders alone influences other preferences. The former hypothesis is unlikely, because it has been found that gender differences among students are exaggerated, especially in attitudes towards controversial animals that pose the threat of injury to humans (Prokop & Tunnicliffe, submitted), but not to generally non-threatening animals like birds (Prokop et al., 2008). Considering that negativistic and scientistic attitudes towards controversial animals are linked (Prokop et al., 2009a), it can be speculated that increasing interest in spiders was linked with decreasing fear of spiders. Further research is needed to determine how increased interest in controversial animals like spiders influences attitudes toward them in both males and females.

The link between knowledge and attitudes

Our research provided evidence for a small, though statistically significant, effect of knowledge on attitudes towards spiders among Slovakian students. On the contrary, among South African students' scores there was only a weak relationship between knowledge and attitude. These results are consistent with our views about the conflict between awareness and evolutionary predisposition to avoid animals that pose physical threat and/or the possibility of disease transmission. We argue that if the probability of being threatened by a particular animal is high, then greater knowledge about this animal is not expected to be linked to attitude (Prokop & Tunnicliffe, 2008;Prokop et al., 2009a). Previous research from Slovakia, however, showed no link between attitude towards and knowledge of spiders, when a nearly identical attitude scale was used (Prokop & Tunnicliffe, 2008). All correlation coefficients between knowledge and ecoscientistic, negativistic, naturalistic dimensions and knowledge were r < 0.1 (all p's > 0.17). However, this research was conducted on a sample of younger children. Considering that children's fears decrease with increase in age [START_REF] Ferrari | Fears and phobias in children: Some clinical and developmental considerations[END_REF], it can be argued that greater fear in younger children could reflect the absence of the attitude -knowledge relationship. If so, this argument also supports our above-mentioned hypothesis that greater conflict between threat (mediated by fear) and knowledge do not result in a strong attitude-knowledge relationship.

In general, our study, like the research of [START_REF] Kuhlemeier | Environmental knowledge, attitudes and behavior in Dutch secondary education[END_REF][START_REF] Makki | Lebanese secondary school students" environmental knowledge and attitudes[END_REF][START_REF] Brossard | Scientific knowledge and attitude change: The impact of a citizen science project[END_REF], supports the idea that there is no strong association between attitude and knowledge. At first glance this is surprising because students who know more about spiders are generally more interested in and less afraid of them. There are at least two explanations for this phenomenon. Firstly, attitudes towards animals at the age of our student sample are developing; they are not yet defined [START_REF] Kellert | Attitudes towards animals: Age-related development among children[END_REF]. In the present study, an overall correlation for attitude and knowledge is 30. However, previous research by Prokop and Tunnicliffe (2008) found no correlation between attitude towards and knowledge of spiders.

In summary, we expect that age-related changes in factual knowledge in young participants

are not yet linked to attitudes and fears as these are not yet defined [START_REF] Røskaft | Patterns of self-reported fear towards large carnivores among the Norwegian public[END_REF]Prokop et al., 2008). Secondly, the reputation of spiders among humans is worse than that of many other animals [START_REF] Kirkpatrick | Age, gender and patterns of common intense fears among adults[END_REF][START_REF] Davey | The "disgusting" spider: the role of disease and illness in the perpetuation of fear of spiders[END_REF][START_REF] Muris | Common childhood fears and their origins[END_REF]. It is therefore probable that this example is somewhat specific and does not reflect general expectations such as the relationships between knowledge of and attitude towards the environment.

According to previously mentioned research, both types of education, providing information [START_REF] Muris | A dirty animal is a scary animal! Effects of disgust-related information on fear beliefs in children[END_REF]

  spider avoidance (negativistic attitude) also influences students' views on the role of spiders in nature (ecologistic attitudes).

  order. Summed scores provide a composite index of attitude towards spiders. Low scores reflect relatively negative attitudes and high scores reflect positive attitudes. The highest attitude score was 120 and the highest knowledge score was 50. Similarly, mean scores below 3.0 reflect negative attitudes or poor knowledge, and scores above 3.0 reflect positive attitudes or good knowledge. If the overall mean score was about 3.0, attitudes were considered neutral.Two professors of zoology from two different universities and two experts in biology education established the validity of the questionnaire through a review. They were asked whether the items in each dimension were relevant to the aim of the questionnaire. Revisions were based on their comments and suggestions.The attitude scores (n = 24 items) are subsequently submitted to factor analysis (PCA with Varimax rotation) and four factors with eigenvalues greater than 1.0 derived. The four dimensions represented in the rotation matrix are: scientistic, negativistic, naturalistic, and ecologistic. These four factors explain 56 % of the total variance. According to[START_REF] Reckase | Unifactor latent trait models applied to multifactor tests: Results and implications[END_REF], the prime factor should explain at least 20 % of total variance and the difference between the second and third factor should be lower than the difference between the first and

  The four schools participating in this project are all private Catholic schools. Two of these (John Martin Catholic School and St. Bede's) are co-educational (boys and girls), situated in relatively poor areas (urban and rural respectively) and attended only by children from black families. St. Ursula's is a girls-only, traditionally white-only school, but since 1994 it has admitted children from coloured and black families who belong to the middle income group.

  myth is more frequently met among the South Africans (M = 2.80, SE = 0.08) than the Slovakians (M = 3.22, SE = 0.06) (t = 5.20, df = 734, p < .001). A third (35 %) scored that all spiders paralyse their prey with venom. Approximately the same percentage of students (37 %) believed that spiders are particularly dangerous at night when people are asleep. This myth, too, was more widely spread among the South African (M = 2.64, SE = .09)

Fig

  or they simply do not favour the protection of spiders because of their low popularity.

  analysing the Slovakian sample, a significant model emerged (F 1,352 = 37.16, p < .001, adjusted R 2 = 0.10). This model accounts for 10 % of the variance, and indicates dependency between the scientistic dimension and knowledge of spiders, because other variables were excluded from the model. A different situation was found in South Africa. Although a significant model emerged (F 1,380 = 12.75, p < .001, adjusted R 2 = 0.03), it explains only 3 % of variance. This model represents an association between the ecologistic dimension and knowledge of spiders. Other predictors were excluded from the model. In summary, attitudes towards spiders in Slovakian students are partly influenced by scientistic attitudes. In contrast, South African students show a weak association between attitudes and knowledge and the knowledge score is partially associated with their ecologistic attitudes.

  research by[START_REF] Gerdes | Spiders are special: fear and disgust evoked by pictures of arthropods[END_REF] who also did not support the 'disease avoidance' hypothesis in their comparison of human fear of spiders and other arthropods. The same hypothesis does not explain why Slovakian students are less interested in the biology of spiders (the scientistic dimension), the role of spiders in nature (the ecologistic dimension), and direct contact with spiders (naturalistic dimension). Compared to Slovakian students South African students have closer contact with nature which might account for their more positive attitude towards spiders. However, more conservative comparison of Catholic schools revealed that South African students have greater fear of spiders than Slovakian students.

Figure 1 .Figure 2 .Figure 3 .Figure 4 .

 1234 Figure 1. Analysis of the students' overall responses to the SAQ. Likert scale 1 and 2

  study was conducted between September and October 2007. A total of 354 Caucasian high school students (222 females and 132 males) from four high schools in Slovakia and 382 high school students (324 females and 58 males) from four schools in South Africa participated in the study. Selection of participants was not intentional, but was based on teachers' willingness to administer questionnaires in selected schools. If the teacher agreed, SD = 0.81), their ages being not significantly different (t-test, t = 1.41, df = 734, p = .16).

	F o r
	P
	e
	e r
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the questionnaire was administered to all participants in selected classes irrespective of the participants' attitudes towards animals. The participants ranged from 14 -17 years (M = 15.02,

  Table1should be interpreted with extreme caution. This is because some South African schools were girls-only (single-sex) and all of them were Catholic. This strong gender bias does not allow us to compare Catholic vs. non-Catholic schools, because the results of such statistical analysis would be interpreted as differences between Catholic and single-sex schools, or South African and Slovakian, but not Catholic and non-Catholic schools. We therefore prefer comparisons based on gender and country in this research, rather than differences among schools, to avoid an inaccurate interpretation of data. For this purpose, dependent variables (knowledge or attitudes) were controlled for the effect of age and school by calculating residuals from regression analysis.

	F o r
	P
	e
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	y

  Catholic schools (A. Merici and ESA) and two coeducational South African Catholic schools (John Martin Catholic School and St. Bede's) entered this analysis, because all of them are

	Catholic, attended only by indigenous Africans (South Africa) or white (Slovakia) males and
	females. Two-way MANOVA supported previous analysis: attitude towards spiders were
	influenced by country (Wilk's λ = .71, F 4,384 = 39.16, p < .001, η 2 = .29) and gender (Wilk's λ
	= .85, F 4,384 = 16.52, p < .001, η 2 = .15). Univariate results revealed similar differences
	F between countries: South African children scored higher in the scientistic and ecologistic o r dimensions (F 1,387 =91.62 and 16.78, respectively, all p < .001), but there was no difference in
	naturalistic dimension (F 1,387 =0.25, p = .64). Interestingly, Slovakian children scored P e significantly higher in the negativistic dimension (F 1,387 =13.01, p < .001) which means that
	South African students are more fearful of spiders than the Slovakian students. Males scored e r always higher than females.
	R
	e
	v i e
	w
	O n l
	y
	Only two Slovakian

uk International Journal of Science Education

  and field trip experiences(Žoldošová & Prokop, 2006) significantly influenced the students' fear of and/or interest in controversial animals. Further research focused especially on controversial animals would shed more light on the relationship between attitude and knowledge.High school students' attitudes towards spiders showed several differences with respect to their country of origin, which should be driven by evolutionary pressures, or improved science education strategies. Irrespective of this, however, spiders were viewed negatively in each attitude dimension. The bad image of spiders is linked to non-supportive ecological attitudes which consequently may influence their (low) protection and the next generation's poor understanding of the role of arthropods in nature. Elimination of myths and enhancement of knowledge resulted in more positive attitudes, especially in Western cultures. It was repeatedly found that spiders are only rarely kept as pets (Prokop, Prokop, & Tunnicliffe, For example, South Africa started the Spider Educate programme 10 years ago and has reached about 20 000 children from nursery schools to university level. Personal experiences of lecturers suggest that more knowledge helps to overcome fear. Emphasizing the "nicer side" of spiders (for example maternal care, colour change, etc.) as well as drawing their attention to beautiful spiders may help especially children to overcome their fear. Finally, our study suggests that planning educational strategies should take into account evolutionary pressures, which could be responsible for human attitudes toward wild animals.Journal of EnvironmentalEducation, 31, 26-31. Thompson, T. L., & Mintzes, J. J. (2002). Cognitive structure and the affective domain: on knowing and feeling in biology. International Journal of ScienceEducation, 24(6), 645-660.Appendix A. Tabulation of the modified(Prokop & Tunnicliffe, 2008) Spider Attitude Questionnaire (SAQ) divided to the four dimensions. Students are requested to respond to the following statements on a Likert five point scale. Negative items are scored in reverse order.NegativisticWhen a spider is making a web in my window, I am unable to sleep N If I happen to find a spider in my room, I will probably run away N

	useful in guiding curricular efforts, especially those concerned with the conservation of
	terrestrial environments.
	Treffers (Eds.), Anxiety disorders in children and adolescents: research, assessment and Spiders scare me more than other animals N
	Conclusion intervention (pp. 187-211). Cambridge: Cambridge University Press. I feel fine about catching a spider if I am wearing gloves	P
	F o r F o r F o r F o r F o r F o r F o r F o r Vetter, R.S., Visscher, P.K. (1998). Bites and stings of medically important venomous arthropods. International Journal of Dermatology, 37(7), 481 -496. Wilson, E. O. (1987). The little things that run the world (the importance and conservation of F o r Scientistic Positive (P) or negative (N) items F o r If somebody tells me that spiders are somewhere around me, I get nervous N I do not like pictures of spiders N F o r
	P e P e P e P e P e P e P e P e invertebrates). Conservation Biology, 1(4), 344-346. Žoldošová, K., & Prokop, P. (2006). Education in the field influences children's ideas and P e I would like to read a book about spiders P I would like to know more about large tropical spiders species P Even the thought of touching a spider scares me N P P e Cronbach's α = 0.818 e
	e r R e v i e w 2008; Prokop, Özel, & Usak, 2009). However, keeping various pets is associated with better knowledge and more favourable attitude towards wild (even less popular) animals (Prokop et al., 2009b; Prokop & Tunnicliffe, in press). We suggest that biology/science teachers should encourage children to keep spiders that can be obtained and reared easily. Special attention e r R e v i e w e r R e v i e w e r R e v i e w e r R e v i e w e r R e v i e w e r R e v i e w e r R e v i e w interest toward science. Journal of Science Education and Technology, 15(3), 304-313. e r R e v i e w I would like to know how scientists investigate spiders P I would like to know more about the weaving behaviour of orb-spiders e r Naturalistic e r P I like watching natural history films about spiders P We should learn more about spiders in school R e I would like to camp at a river near spiders P Capturing spiders is exciting R P e P I would like to participate in an expedition to investigate spiders P v i e I would like to have some spiders in the roof of my house P I would like to live in a country with few spiders N v i e Cronbach's α = 0.895 w I would rather avoid places with spiders N I would like to catch a spider with my bare hands P w
	O n l y should be focused on children from black families, because these children showed greater fear of spiders than white children from Slovakia. The research instrument presented in this paper may be useful in assessing student's O n l y O n l y O n l y O n l y O n l y O n l y O n l y O n l y Ecologistic Greater attention should be given to spider protection P Spiders are quite interesting animals O n l Cronbach's α = 0.762 O n l P y y
	knowledge and attitudes. Greater emphasis on research into teaching strategies about spiders
	People should use fewer chemicals in order to allow spiders to live close
	(arthropods) in formal and informal biology settings and an improvement in teachers'
	to them	P
	knowledge about student's views of spiders would be beneficial in formulating new strategies
	I would like to watch a spider constructing its web at night	P
	on how to impart knowledge of these controversial animals. We hope that our study may be
	Cronbach's α = 0.688
		2 3

Page 32 of 39 URL: http://mc.manuscriptcentral.com/tsed Email: editor_ijse@hotmail.co.

Table 1 .

 1 Differences in mean scores between schools calculated by ANCOVA (controlled for age). Values are means and standard errors (in parentheses). S = state school, † = Catholic school, ♀ = single sex schol (girls only), **p < .01, ***p< .001, ns = non-significant.

	Slovakia

URL: http://mc.manuscriptcentral.com/tsed Email: editor_ijse@hotmail.co.

uk International Journal of Science Education

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URL: http://mc.manuscriptcentral.com/tsed Email: editor_ijse@hotmail.co.ukInternational Journal of Science Education

Acknowledgements

We would like to thank Ansie Dippenaar-Schoeman and two anonymous referees for insightful comments on earlier drafts of the paper. We are very grateful for Pam Thornley's contribution to the improvement of the English language in this paper.


M Dubois

P Jardin

O Bajeat

C Barue

C Canet

M Dupuis

J L Flambard

R Frigot

C Leboucher

N Lecesne

P Lecomte

P Leherissier

F Lemagnen

L Maunoury

B Osmond

J Y Pacquet

A Pichard

MONOBOB II : LATEST RESULTS OF MONOCHARGED IONS SOURCE FOR SPIRAL2 PROJECT

Among the sources which can be installed in the radioactive ion production module of SPIRAL II, a singly-charged ECRIS has been chosen to produce ions from gaseous elements. Its characterization is under way on a test bench at GANIL. Extraction, transport and response time results are presented.

INTRODUCTION

In the frame of the SPIRAL II project [START_REF] Lewitowicz | The SPIRAL 2 Project[END_REF] (Système de Production d'Ions Radioactifs Accélérés en Ligne phase II), four techniques of ion source (IS) have been chosen to cover a large range of radioactive ions, i.e. FEBIAD and LASER [START_REF] Lecesne | GISELE: A resonant ionization laser ion source for the production of radioactive ions at GANIL[END_REF] IS's for condensable elements, surface IS [START_REF] Pichard | Development of a surface ionization source for the SPIRAL 2 project[END_REF] for alkalis, and ECRIS [START_REF] Huet-Equilbec | MONOBOB: A radiationhard and efficient 2.45-GHz ECRIS dedicated to radioactive ion production[END_REF] for gaseous elements. These sources can be installed in a vacuum chamber named "production module" which contains mainly the radioactive element production target and the IS. To limit the transient time of the atom from the target to the IS, the source is installed very close to the target. In this hostile environment, a standard ECRIS including permanent magnets and non mineral insulators cannot withstand the radiation dose more than few days, what must be compared to the three months of continuous operation expected. Then the techniques and materials available to design the sources are limited and only singly-charged IS can be built. To reach the charge states required by the post accelerator CIME [START_REF]Cime Working Diagram[END_REF] the delivered beams are then injected in a charge-booster [START_REF] Lamy | Charge breeding method results with the phoenix booster ECR ion source[END_REF].

The most interesting isotopes are the shortest lived ones; unfortunately, their production yields in the target decreases with their half-lives, and their losses tends to increase during the atom-to-ion transformation process as their half-lives decrease. The efficiency of each step of the process, diffusion of the isotopes out of the target, effusion up to the IS, ionization and transport must then be as high as possible to make the most of the isotopes produced in the target. By difference with stable elements, the process must also be as fast as possible to limit the losses by radioactive decay.

In this paper, we report the measurements of the beam transport from the exit of the ECRIS up to the Faraday cup situated after a magnetic mass spectrometer, the emittance measurement and the measurement of the atomto-ion transformation time in the ECRIS.

DESCRIPTION OF THE SETUP

For gases, the production module includes a carbon converter, a uranium carbide target with its oven, a transfer tube and an ECRIS (Fig. 1). A primary beam of deuterons impinges the carbon of a wheel in front of the UC target, producing a flux of neutrons which induces the fission of the uranium. As the target is maintained at 2000°C, the fission fragments diffuse out of target material, effuse up to the ECRIS via the transfer tube and are ionized in a time and with an efficiency depending on the tuning of the source and of the element. The ions leave the IS trough the hole of the plasma electrode (7 mm in diameter) placed in front of the extraction electrode (14 mm in diameter, and with a tuneable position). The potential difference was maintained at 15 kV. After acceleration, the beam passes through an Einzel lens (with tuneable position), a magnetic mass analyser, an emittance meter (removable), before reaching a Faraday cup.

For safety reasons, in the frame of SPIRAL II operation, the TISS will be installed in a vacuum chamber where the pressure must be lower than 10 -5 mbar after outgassing. During the present tests, the vacuum chamber reproduces these vacuum conditions, but the UC pills were replaced by carbon pills.

Two fast valves were installed on the TISS: one at the opposite of the plasma electrode hole to measure the response time of the source, and one on the target container, at the opposite of the aperture towards the IS to measure the contribution of the target to the response time of the TISS.

Fast valves were fed with a mixture of He, Ne, Ar, Kr, and Xe. Support gas was N 2 , 0 2 being forbidden in case of carbon target at high temperature (max 1500°C).

TRANSPORT OPTIMISATION

The optimal distance between the extraction and plasma electrodes has been found equal to 31 mm. The transport of the beam from the exit of the ECRIS up to the Faraday cup has been estimated by comparing the total current of the peaks present on the spectrum and the total current delivered by the ECRIS. The position of the lens and of its voltage were tuned to maximize the current of the N 2 + beam in the Faraday cup, as this ion beam is the most abundant and then mainly govern the value of the transport (Fig. 2). The total current delivered by the source was maintained between 640 µA and 810 µA, what is close to the maximum of this source. Once a transport close to 100% has been obtained, the emittance has been measured for Ar + (Fig. 3) and N 2 + beams. More than 85% of the beam is included in an ellipse of 80 π.mm.mrad, which corresponds to the acceptance of the low energy beam line. This result should be improved by increasing the magnetic field of the ECRIS in the extraction region. During the tests, this magnetic field was not optimum owing to a limitation of the power supplies, and will be improved during the next tests. The emittance of the ECRIS being considered as the most important among the IS chosen, all the beams extracted from these ISs should be easily transported in a 80 π.mm.mrad beam line.

RESPONSE TIME

The source was fed with N 2 and ~50 W of RF power (less than 5 W of reflected power) to reach a total current between 640 µA and 810 µA at the exit of the source. Gas pulses of ~1.4 ms long were injected in the source, containing natural He, Ne, Ar, Kr and 129 Xe (Fig. 4). The magnitude of the electrical pulses controlling the aperture of the valve was tuned to limit the perturbation to value lower than 5 µA induced on the plasma and thus on the total current. The ion beam of interest was selected with the spectrometer and the shape of the ion pulses was recorded on the Faraday cup. The intensities of the ion pulses being of the order of 10 nA, several pulses were added to increase the statistic. To reject the 50 Hz noise, the repetition period of the pulses was different from a multiple of 20 ms. During the following measurements, the temperature of the target was equal to 1000 K. Owing to two half discs placed in the transfer tube, the target and the ECR plasma were not in direct regard. This TISS being dedicated to the production of isotopes of noble gases, this chicane stops the direct effusion of condensable element from the target to the source. conditions of the source, as gases were simultaneously injected (Fig. 5). The response time increases with the mass of the gas. This effect is mainly attributed to the effusion of the atom in the whole cavity of the TISS, and should then depend on the square root of the mass of the element considered If the time scale of each response is compressed according to the ratio ⁄ (where M X corresponds to the mass of the gas X and M He is the mass of He), the different responses should be identical if only effusion governed the time responses. In fact, within this compressed scale representation, the time response decreases with the mass of the element (Fig. 6). To understand it, measurements were performed with injection of gas directly in the source (VP source). After time scale transformation (Fig. 7), the result show is due to the first ionization potential which decreases with the mass and leads to ionization rates higher for heavier elements. In case of radioactive isotopes, this observation is of first interest since the global atom-to-ion transformation process of heavier elements will be shortened by ionization efficiency, increasing the ion production rate.

The contribution of this effect to the reduction of the global response time is relatively small (some tens or hundreds of ms) compared to the effusion time of the isotopes out of the target labyrinth (Fig. 5). But in case of short lived isotopes, the size of the target could be reduced to limit the inner-target effusion time.

TECHNICAL FEEDBACK

The TISS has been designed to withstand the dose around the UC target. Materials are only non-magnetic metals and mineral insulators. The TISS being installed under vacuum, the mechanical precision between the parts is sufficient to insure the tightness.

After several weeks of operation with a carbon target in its vicinity, the ECRIS still works but the total operation time has not been precisely measured. A layer of carbon appears on the wall of the plasma chamber but its thickness must be very low since the color of the wall metal is still visible. The carbon deposition is an important concern especially for RF window: if covered by carbon, the RF power will be reflected, and the window will be destroyed by temperature increase. The carbon in the ECRIS comes from the target and its oven, which includes several parts in graphite. When the target is at high temperature, the carbon reacts with oxygen coming from the outgassing and is transported up to the source as CO or CO2 molecules, which are present in the source spectrum (Fig. 2, right part).

When the outgassing is less important, the presence of oxygen decreases and the carbon disappears from the spectrum. The system has then to be well outgassed before operation to avoid carbon concerns.

Figure 1 :

 1 Figure 1 : Production module

Figure 2 :

 2 Figure 2: typical spectrum of the source after mass spectrometer after outgassing.

Figure 3 :

 3 Figure 3: Emittance of the 40 Ar + beam for a total current extracted from the source of 735 µA. The ellipse corresponds to the geometrical acceptance of the low energy beam line (80 π.mm.mrad).

Figure 4 :

 4 Figure 4 : Set up scheme

Figure 5 :

 5 Figure 5: Time responses (s) of the TISS for He, Ne, Ar, Kr and Xe injected through the target. The target was the largest one, including 19 cylinders of 80 carbon pills each.We recorded the response time of the atom-to-ion transformation for different gases in the same working

Figure 6 :

 6 Figure 6: time responses of the TISS after time scale transformation. Injection has by the target (VP target).

Figure 7 :

 7 Figure 7: Time responses of the source for He, Ne, Ar, Kr and Xe in the same plasma conditions, after time scale transformation. Injection of gas in the source (VP source).

Proceedings of ECRIS2010, Grenoble, France


Beam evolution during long term period

The Fig. 4 graphic shows the evolution of the beam during 1 hour using UDV valves and Mass Flow Controller.

The big wave observed is due to the start and stop of the air-conditioning system in Pantechnik's test-room. The Mass-flow is insensitive to low variation of temperature (+-2°C) which is a requirement for Hadrontherapy [3].

The mean noise is lower with Mass Flow, the reason is the following: The gas mixing rate between support and main gas is maintained constant with the two Mass Flow while it can change with UDV140.

The Fig. 5 shows the evolution of the beam during 10 hours using UDV valves. The test with Mass-flow is in progress at Marburg's Hadrontherapy Center.

SYSTEM REPRODUCIBILITY WHEN CHANGING THE FLOW

In order to demonstrate the reproducibility of the system, the flow of the He gas has been changed and came back to the original value (see Fig. 6). There is no hysteresis effect like in UDV dosing valve and the reactivity is <5s.

The flow can be adjusted to the set point with a ramp (arrows 2, 4, 5, 6) or without (arrows 1, 3).

The flow has been changed with a step= 0.5% (of the max aperture) on arrow 1 and 2.

The ion source is insensitive to changes smaller than 0.5% for this tuning.

On arrows 3, 4 and 5, 6, the flow has been changed with a step=+/-1.25% , the ion beam current is restored. The opening is linear and the step resolution is around 1.4E-7 mbars. The response time is less than 3s for small step.

INJECTION PRESSURE ACCURACY

The range goes to 2.10 -7 to 5.10 -5 mbar with He Gas and 2.10 -7 to 2.10 -4 mbar with H 2 .

We conclude that we can have a very good accuracy on the flow. Nevertheless, further tests with others gases and high charge state will be studied in a close future. The step at 60% for H2 (Fig. 8) is due to the range of the Injection Pressure monitor (10E-5 to 10E-4) so it changes calibration (Pirani gauge).

NEXT STEP: SMART BENCH FOR ECR SOURCE (AUTOMATIC SOURCE)

We already know that UDV valve provided a good stability [4] but the main defaults in this system are:

• The high sensibility to the temperature's variations. • Hysteresis shape of valve thermo-mechanical response. The main issue for having a stable beam from an ECR Ion source is the precise control of the gas flow.

Today, we can consider building a smart system for producing Ion beam dedicated to hadron therapy with:

• A high reproducibility of beam parameters.

• An insensibility to low temperature variation.

• And a stable beam with a good Emittance during several weeks without any intervention of operators. The future system will allow selecting the type of ion (example C 4+ ) and the intensity (200μAe). The system will self-adjust Gas, Focus, Puller, RF-tuner, Frequency and RF power parameters for reaching the desired values after several minutes.

  Figure 1: Sch

Figure 4 :

 4 Figure 4: C 4+ stability during 1 hour.

Figure 5 :

 5 Figure 5: C 4+ stability during 10 hours.

Figure 6 :

 6 Figure 6: System reproducibility with He + .

Fig. 7

 7 Fig. 7 & 8 display the result of test made on Supernanogan with injection turbo-pump. A calibration curve has been done on 2 different gases in order to investigate the behaviour of the valve and its resolution. We recorded (by step of 0.1% of the maximum flow) the injection pressure (without beam).The opening is linear and the step resolution is around 1.4E-7 mbars. The response time is less than 3s for small step.The range goes to 2.10 -7 to 5.10 -5 mbar with He Gas and 2.10 -7 to 2.10 -4 mbar with H 2 .We conclude that we can have a very good accuracy on the flow. Nevertheless, further tests with others gases and high charge state will be studied in a close future.

Figure 7 :

 7 Figure 7: System reproducibility with He.

Figure 8 :

 8 Figure 8: System reproducibility with H 2

Table 1 :

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Bougy, N. B

A.C.C.

Proceedings of ECRIS2010, Grenoble, France TUPOT00602 New Development

Proceedings of ECRIS2010, Grenoble, France

Proceedings of ECRIS2010, Grenoble, France TUPOT006


Smaïl Akkoul
email: smail.akkoul@univ-orleans.fr

Roger Ledee

Remy Leconge

Christophe Leger

Rachid Harba

Sabrina Pesnel

Stéphanie Lerondel

Alain Lepape

Comparison of Image Restoration Methods for Bioluminescence Imaging

Keywords: Restoration methods, Bioluminescence Imaging, acquisition models

Bioluminescence imaging is a recent modality to visualize biological effects more especially for small animals. However the acquired images are degraded by diffusion and absorption phenomena from the tissue and by the acquisition system itself. In this paper, we use restoration methods to enhance the quality of bioluminescence images. We propose a model for image formation and an experimental determination of the PSF (Point Spread Function). Several methods of restoration are compared on test images generated according to the model and on real data. This comparison is insured by using MSE (Mean Square Error) and two quantitative criteria. Results establish that the statistical methods give more accurate restoration and well adapted for Bioluminescence Imaging.

Introduction

During the last years, research showed that there were numerous concordances between the human genome and that of primates, and mice [START_REF] Beck | Genealogies of Mouse Inbred Strains[END_REF]. With mice, the advantages are that we have a short generation time and convenient breeding conditions. It is possible to manipulate their human equivalent genes [START_REF] Contag | Use of Reporter Genes for Optical Measurements of Neoplastic Disease In Vivo[END_REF] to create models of human diseases [START_REF] Edinger | Advancing Animal Models of Neoplasia through in Vivo Bioluminescence Imaging[END_REF]. But in vivo studies on these models need the development of novel methods of investigation adapted to small animals.

Among the emergent techniques for in-vivo investigation of the small animal, bioluminescence imaging (BLI) [6,7] proves to be very promising. Bioluminescence is a chemical reaction which produces visible light that can be observed in a variety of marine and terrestrial animals, more especially in the firefly [START_REF] Greer | Imaging of Light Emission from the Expression of Luciferases in Living Cells and Organisms: A Review[END_REF][START_REF] Roda | [END_REF]. This imaging modality presents several advantages like its simplicity. It is non-invasive, low cost and it is at the same time, a functional and metabolic imaging of a gene expression [START_REF] Roda | [END_REF]. Currently, it is exploited in complement of other methods [START_REF] Rehemtulla | Rapid and Quantitative Assessment of Cancer Treatment Response Using In Vivo Bioluminescence Imaging[END_REF], to monitor biological processes during time for tumors detection, drug therapy assessment and for follow-up of the neoplasic evolution [START_REF] Contag | Use of Reporter Genes for Optical Measurements of Neoplastic Disease In Vivo[END_REF][START_REF] Edinger | Advancing Animal Models of Neoplasia through in Vivo Bioluminescence Imaging[END_REF].

Nevertheless diffusion and absorption of light by the tissues [6] make this method difficult to use in practice, mainly when quantitative imaging is required. Moreover, the acquisition process introduces a point spread function which makes that acquired image is not matching to the reality [START_REF] Rehemtulla | Rapid and Quantitative Assessment of Cancer Treatment Response Using In Vivo Bioluminescence Imaging[END_REF]. One of the possible solutions to correct these effects would be to use image restoration methods to recover the original light sources [START_REF] Banham | Kastaggelos: Digital Image Restoration[END_REF]. As bioluminescence imaging is quite a new technique, no such work has been carried out to our knowledge.

In this study, the image restoration process is used to improve the quality and recover the spatial resolution of bioluminescence images. We investigate several methods of restoration and compare them on test images and real acquisitions.

This communication is organized as follow. In the second section, we present the material, the modeling of the system and all the methods of restoration studied as well as the parameters of comparison. The results obtained on synthesized images and real images are presented in third section. Conclusions of this work form the last section.

Materiel and Methods

Acquisition System

Bioluminescent imaging offers many opportunities for non-invasive study using reporter genes. Tagged cells are labeled with reporter genes encoding luciferase enzymes in living small animal. To monitor the evolution of tagged cells, substrate luciferin is applied to the animal by injection. Those cells that express the luciferase transgene emit photons. The mice were anesthetized, and placed onto warmed stage inside camera box. Our bioluminescent images were acquired for one minute with a commercial unit (Hamamatsu, Macroscopic Imaging AEQUORIA), that comprises, a light-tight cabinet with a high sensitivity cooled CCD camera. The images obtained have a resolution of 512x512 pixels coded on 16 bits and 300 µm space resolution. An example of acquisition is presented in figure 1.

Acquisition Model

The formation of the images of bioluminescence results from the counting of photons emitted by a source radiating in all directions starting from the inside of the small animal and which is collected outside by the CCD camera. The light intensity of the sources is low and photon propagation is subject to both scattering and absorption phenomena.

In this work, we will only consider subcutaneous tumors which represent 80% of tumor locations in experimental cancerology. So, we can measure the PSF including instrumentation and the skin effects. This is the first stage before including model of diffusion and absorption of the skin in the restoration process. Bioluminescence imaging acquisition process is similar to that of nuclear medicine, astronomical and optical microscopic imaging. All of them use CCD camera and a low light phenomena is recorded. The quantum nature of light leads to a Poisson modeling of the signal emitted by the object. Recent works on these imaging modalities provide reviews of proposed models [START_REF] Lantéri | Restoration of Astrophysical Images -The Case of Poisson Data with Additive Gaussian Noise[END_REF][START_REF] Sarder | Deconvolution Methods for 3-D Fluorescence Microscopy Images[END_REF]25]. The camera is cooled (-75°C) to be extremely sensitive to the observed phenomena. Nevertheless, images are degraded by a noise due to CCD camera read-out, quantization, and dark current [START_REF] Snyder | Image Recovery from Data Acquired with a Charge-Coupled-Device Camera[END_REF]. The additive noise is supposed to be a zero mean Gaussian noise of unknown variance σ 2 . We propose to adopt for the bioluminescence imaging a Poisson model. This model is expressed as:

𝑖(𝑥, 𝑦) = 𝑝( 𝑜 𝑥, 𝑦 * 𝑥, 𝑦 ) + 𝑏 𝑥, 𝑦 , (1)
where i: is acquired image, o: real image, h: point spread function, *: convolution product, p is the Poisson process, b: the additive Gaussian noise.

Restoration Methods

The image restoration process is used to reduce the effects of the blur. This inverse problem has led to a large amount of work [START_REF] Banham | Kastaggelos: Digital Image Restoration[END_REF][START_REF] Biemond | Iterative Methods for Image Deblurring[END_REF][START_REF] Richardson | Bayesian-Based Iterative Method of Image Restoration[END_REF][START_REF] Dempster | Maximum Likelihood from Incomplete Data Via the EM Algorithm (With Discussion)[END_REF][START_REF] Katsaggelo | Iterative Image restoration Algorithms[END_REF], the main difficulties being the determination of the PSF and the additive noise [START_REF] Rooms | PSF estimation with application in auto focus and image restoration[END_REF][START_REF] Du | Effects of Point-Spread Function on Calibration and Radiometric Accuracy of CCD Camera[END_REF]. Many classifications are proposed in the literature [START_REF] Sarder | Deconvolution Methods for 3-D Fluorescence Microscopy Images[END_REF]25]. In our work we propose to classify used methods in four classes: linear, nonlinear, statistical, and blind methods.

The first class concerns the linear methods, like Wiener [START_REF] Banham | Kastaggelos: Digital Image Restoration[END_REF][START_REF] Prakash Dhawan | Image Restoration by Wiener Deconvolution in Limited-View Computed Tomography[END_REF] filter or that of Tikhonov-Miller [START_REF] Van Kempen | A Quantitative Comparison of Image Restoration Methods for Confocal Microscopy[END_REF][START_REF] Sarder | Deconvolution Methods for 3-D Fluorescence Microscopy Images[END_REF]. To decrease the sensitivity to noise of the inverse filter and its singularities, the Wiener filter minimizes the mean square error between the original image and the restored one. It is easy to implement, but it requires a good knowledge of the noise spectrum. It is expressed:

𝑀𝑆𝐸 = 𝐸 𝑜 𝑥, 𝑦 -𝑜 (𝑥, 𝑦 2 .
(

) 2
The Tikhonov-Miller filter found when minimizing the Tikhonov functional, which is the square difference between the acquired image and blurred estimate of the original object regularized by a Tikhonov energy bound. It is expressed:

𝜙(𝑂 𝑥, 𝑦 ) = 𝑎𝑟𝑔𝑚𝑖𝑛 𝑖 𝑥, 𝑦 - * 𝑜 (𝑥, 𝑦) 2 + 𝜆 𝑝 * 2 , (3)
where, the first term represents the fidelity to the data I(x, y), and the second the smoothing applied to the restored image: p is high pass filter, 𝜆 is the regularization parameter and represents the trade-off between the fidelity to the data and the smoothness of the restored image and the original image. This method is simple to implement, but it is very sensitive to errors in the PSF data used for estimation, leading to ringing artifact in the solution.

The second class includes the nonlinear methods. To solve the difficulties occurring within this class, constraints were integrated in these linear methods. Historically, the Jason-Van Cittert's algorithm is the first constraint method. It is an iterative algorithm that converges quickly. But it is not very effective in the case of images having a low SNR. Thereafter, this algorithm was improved by introduction of other constraints like limiting the intensity of the signal for example. A nonlinear approach of Tikhonov-Miller algorithm was also proposed. The minimum of the Tikhonov function is reached iteratively by clipping the estimated negative intensities to zero after each iteration. Usually, a conjugate gradient (CG) method is used for the iterative search operation [START_REF] Van Kempen | A Quantitative Comparison of Image Restoration Methods for Confocal Microscopy[END_REF]. During iterations, the steepest descent in direction of minimum of the function is calculated. The solution is expressed as:

𝑂 𝑘+1 = 𝑂 𝑘 + 𝑠 𝑘 𝑝 𝑘 𝑖𝑓 𝑂 𝑘 + 𝑠 𝑘 𝑝 𝑘 ≥ 0 0 𝑜𝑡𝑒𝑟𝑤𝑖𝑠𝑒 , (4)
where s k is the size of the optimal step and p k the conjugate gradient direction.

The improvement of this algorithm was the objective of many work but all are based on the assumption that the nature of the noise is Gaussian [START_REF] Van Kempen | A Quantitative Comparison of Image Restoration Methods for Confocal Microscopy[END_REF].

To take into account other physical model as Poisson process, statistical methods were proposed and are classified in third class. Statistical methods are based on the Bayes's rule. Consisting to construct the conditional probability density relationship:

𝑃(𝑂/𝐼) = 𝑃(𝐼/𝑂)𝑃(𝑂)/𝑃(𝐼) , (5)
where . In both cases P(I) is considered as constant value which has not effect in the maximization process, and is ignored. In this class, the Lucy-Richardson algorithm [START_REF] Richardson | Bayesian-Based Iterative Method of Image Restoration[END_REF][START_REF] Shepp | Maximum Likelihood reconstruction for emission tomography[END_REF][START_REF] Dempster | Maximum Likelihood from Incomplete Data Via the EM Algorithm (With Discussion)[END_REF] is an iterative technique used heavily for the restoration based on Bayes approach. It is widely used in the restoration of astronomical images [25]. Blind deconvolution methods represent the last class of algorithms. The performances of the preceding methods are based on a good knowledge of the PSF and also of the noise [START_REF] Kundur | Blind Image Deconvolution Revisited[END_REF][START_REF] Du | Effects of Point-Spread Function on Calibration and Radiometric Accuracy of CCD Camera[END_REF]. The blind methods are more proper when the PSF and noises in the image are both unknown. Many of these algorithms derived from probabilistic modes compute and use the same approach as constrained iteration algorithms, including the both estimation of the PSF and the original image in each iteration. In these methods, estimate PSF can be injected to increase the convergence of calculations.

In addition to these four classes, methods based on the wavelets seem to give good results. In this work, we tested only the methods present in the four classes.

Performance Measurement

To measure the performances of restorations methods we use two tests. First, the restored results are compared at each iteration to original image using MSE. The MSE measures the difference in energy between the two compared images. The MSE is given as:

𝑀𝑆𝐸 = 1 𝑀𝑁 𝑂 𝑖,𝑗 -𝑂 𝑖,𝑗 2 . 𝑖,𝑗 (6)
But this measure is global and sometime it is difficult to choose the best method between many approaches. So, in order to completely assess the success of our restoration procedures, we use a specific evaluation criteria based on that proposed in [START_REF] Webb | Constrained Deconvolution of SPECT Liver Tomograms by Direct Digital Image Restoration[END_REF] and used by Mignotte and Meunier for SPECT images [START_REF] Mignotte | Three-Dimensional Blind Deconvolution of SPECT Images[END_REF]. We define regions of interest (ROI) which are the objects in the test image with a high gray level. In these specific areas, we compute the mean of the gray levels to compare it to the grey level of the same ROI in the original image. Also, standard deviation of this mean is calculated. For a good restoration, the mean value must tend to the original value and the standard deviation must decreases towards zero.

Experiments and Results

PSF of the System

Since the application concerned the subcutaneous tumors, we record the PSF of the acquisition system including the skin of mouse in order to take into account for the phenomena of absorption and diffusion of this part of the animal. To do that, we realized an acquisition system which is composed by a point source obtained using optical fiber which diameter of the heart is equal to 200µm, lower than the size of a pixel of the image (size of the pixel being of 300µm). To remain in the spectral band of the luciferase in vivo, the optical fiber is supplied by a white light source filtering by two interferometric filters. Then, to reduce the effects of the noise, the acquisition was carried twenty times under the same conditions and the sum of acquisitions was divided by the number of acquisitions.

Generation of Test Images

To test the performance of the restoration algorithms, we generated two test images integrating the imperfections of the acquisition system. The images are realized as a convolution between the undistorted image of shapes and the experimental PSF. Then, Gaussian noise of the system is added to respect equation 1. The figure 4 represents the two test images before and after degradation. The first image is formed by a disc of ray 2.25 mm with a uniform intensity of 6.10 4 and the second by two small close discs of ray 900 µm separated by 300 µm.

Restoration of the Test Images

First, we have tested the deconvolution methods on test images. The advantages to work with synthetic degraded images are that we know exactly the initial object, and the degradation model. Then, it is easy to quantify results by comparing the restored image to the original image (figure 4a). To quantify the general quality of restoration, we compute the MSE between the restored image and initial undegraded image for each method and for each iteration. We report on the table 1 two objects after restoration with the minimum measure of the MSE. In first consideration, we observe that statistical methods and the Tikholov Miller method with a good choice of parameters give the best results. But the level of gray under the shapes presents ringing artifacts. The second experiment tests the ability of the methods to improve the quantitative measurement of the total amount of bioluminescence inside the disc area (ROI). The figures 5a and 5b show the evolution of the two parameters as function of iteration number. From figure of mean we can see that this parameter for all methods converges to the real value (6 10 4 ) except for gradient conjugate which over-estimates this value. For the standard deviation the statistical methods have small gap and continue to decrease with iterations. On the other hand the nonlinear methods diverge after some iterations. To obtain a quantitative comparison, we take the two parameters with their optimal values i.e. the value of the number of iterations corresponding to minimum of the MSE. This result is summarized in table2.

With our criteria exposed in II.4, in the table 2 and with the first results (table 1), it is easily seen that statistical restoration methods give good results. Tab.2. Mean and standard deviation of the ROI after deconvolution for each method.

Bioluminescence Images Restoration

We have also tested the deconvolution algorithms on real bioluminescence images. We present two cases where the ROI of the real acquisition are reported in the table 2. The obtained results are showed in table 2 and we can see that statistical methods give restored images with limiting ringing artifacts and good spatial resolution. Note that it is difficult to define a quantitative measure of the deconvolution results because we do not know the original image.

Linear Methods Nonlinear Methods Statistical Methods Blind Methods

Real

Conclusions

In this work nine algorithms for restoration methods were tested and compared on test images and on real bioluminescence images. To do this, we have defined a physical model of bioluminescence imaging formation. Then, we used an experimental approach to estimate more accuracy the point spread function of the acquisition system including the skin of mice. These allowed us to simulate synthetic data. After having defined and used comparison criteria, we conclude that statistical methods are more appropriated to bioluminescence imaging. On real data, we have noticed that the statistical restoration methods improve the contrast and spatial resolution of these images. To confirm this study, we will carry out physical measurements on small tumors and compare them to measures extracted from restored images.

Fig. 1 .

 1 Fig. 1. (a) Example of a bioluminescence acquisition, (b) Fusion between of the bioluminescence image and visible light image.

  P(O/I) denotes the probability density function (pdf) of O given I, P (O) denotes the pdf of real image, and P(I/O) denotes the a priori probability. The objective is to find an estimate of the original image which maximizes the posterior probability. The maximization of the right part of the equation gives a solution O. This is obtained by only the maximization of the density P(I/O) over O (likelihood solution (ML)) or by maximization of the product P(I/O) P(O) (maximum a posteriori solution (MAP))

Fig. 1

 1 Fig.1 (a) (b) Test image before degradation (c) (d) Test image after degradation

Fig. 5 .

 5 Fig.5. (a) Mean of the ROI at each iteration, (b) Standard deviation of ROI at each iteration.

Tab. 3 .

 3 Restoration of real bioluminescence images with the same condition like tests images.

  Restoration results of the test images by the different methods, with the minimal MSE.

	Tested	Linear Methods	Nonlinear Methods	Statistical Methods	Blind Methods
	Image	W	TM	GM	SD	CG	LR	MAP	SMAR	ML
	MSE (10 6 )	7.312	4.797	5.830	6.008	15.634	4.514	4.5157	4.732	4.441
	N° Iterations -	-	-	20	20	250	250	250	250	250
	Tab.1.

W: wiener, TM: Tikhonov Miller, GM: Golden Meinel, SD: Steepest Decent, CG: Conjugate Gradient, LR: Lucy Richardson, MAP: Maximum a posteriori, SMAR: Simultaneous Multiplicative Algebraïc Restoration, ML: maximum Liklhood.