Defect centre responsible for production of 110 degrees C TL peak in quartz

110 degrees C thermoluminescence (TL) peak in quartz is well known due to its pre-dose effect, which is used in dating technique. The generally accepted mechanism for the production of this peak is based on Ge impurity contained in quartz. Its role is to substitute for Si in SiO(4) tetrahedron and under irradiation gives rise to [GeO(4)/e(-)](-) electron centre. Heating for TL read out liberates electron that recombines with hole in [AlO(4)/h]degrees or [H(3)O(4)/h]degrees centres emitting photon. The investigation, carried out on blue quartz, green quartz, black quartz, pink quartz, red quartz, sulphurous quartz, milky quartz, alpha quartz and synthetic quartz, has shown that the 110 degrees C TL peak in all these varieties of quartz has no correlation with the respective Ge content. Electron paramagnetic resonance (EPR) measurements on any of these varieties of quartz revealed a signal with g(1) = 2.0004, g(2) = 1.9986 and g(3) = 1.974 and this signal does not appear to correspond to any known EPR signals in alpha quartz. Furthermore, isothermal decay measurements are carried out on the above mentioned EPR signal and 110 degrees C TL peak in alpha, blue and green quartz. A close correlation has been observed in the decay behavior. A new mechanism is proposed based on an interstitial O(-) centre. (C) 2009 Elsevier Ltd. All rights reserved.

The Impact of the NIHERST/NGC National Science Centre, Trinidad and Tobago on Visiting Student Groups

The aim of this study was to asses the impact of a visit to the NIHERST/NGC National Science Centre in Trinidad on four different school-age visitor groups. The research was conducted through the administering of a post-visit questionnaire immediately upon completion of each visit by each group, and via visitor feedback obtained in post-visit or pre-visit activities conducted within two weeks of the visit for three groups. Teachers/instructors who accompanied the groups on their visit also completed post-visit questionnaires and provided additional information on follow-up activities via an interview. The results of this investigation suggest that the visit to this science centre provided entertainment/enjoyment value and potential educational value to most individuals. The nature of this enjoyment was noted for various age groups and genders in this study. Quantification of the educational impact was not possible within the constraints of this study, which was unable to capture long-term effects of the supply of ‘new knowledge’ to visitors which the visit to the science centre had provided.

Examining Visitor Attitudes and Motivations at a Space Science Centre

The H.R. MacMillan Space Centre is a multi-faceted organization whose mission is to educate, inspire and evoke a sense of wonder about the universe, our planet and space exploration. As a popular, Vancouver science centre, it faces the same range of challenges and issues as other major attractions: how does the Space Centre maintain a healthy public attendance in an increasingly competitive market where visitors continue to be presented with an increasingly rich range of choices for their leisure spending and entertainment dollars?This front-end study investigated visitor attitudes, thoughts and preconceptions on the topic of space and astronomy. It also examined visitors’ motivations for coming to a space science centre. Useful insights were obtained which will be applied to improve future programme content and exhibit development.

NAVET's Boxes - an Evaluation of the Post-Visit Loan Service at a Science Centre in Borås

Many pedagogues believe science centres to be a good complement to the more formal school teaching. For a visit to a science centre to be as educational as possible, there is a need for pre-visit information of some sort, a guided visit, and post-visit work. Many science centres offer loan services of different kinds. At Navet, a science centre in Borås, teachers can borrow boxes with experiments connected to the different themes they provide. The experiments are supposed to be a continuation of the visit and help settle the knowledge gained during the visit. This thesis is an evaluation of how the boxes function in the schools, and what the teachers think of them. The study was conducted through questionnaires and interviews with both teachers and the staff at Navet. The results of the study are very positive. Many teachers have been involved with Navet from the very beginning and they see a visit to Navet as an integrated part of their teaching. Some boxes work better than others and some might need clearer information, but overall the teachers see the boxes as timesavers, as a way to vary their teaching more easily, and as a help for teachers not specialized in mathematics and science.

Pupils' interaction with a Science Centre: Communication perspective analysis

The purpose of this study was to investigate pupils’ knowledge about science and what role science center is playing as a medium of communication to increase knowledge among students. This study also tried to find out pupils’ interaction: how they use science center as a source of scientific information, what they learn from their visit to a science center, their pattern of communication with it. This project also measured attraction, holding and learning power of exhibits of the science center at Dalarna University in Borlänge and learning power of planetarium program and slide show of Stella Nova Planetarium at Dalarna University.The subjects of this study consisted of students of class seven and eight and teachers of an urban school in Borlänge, Sweden. To find out students’ learning in a science center a pre and post visit test were conducted through questionnaires. Interview method by questionnaires was also used to explore pupils’ interaction with science center.The results of this study show that students learn by their visit to a science center but learning was not statistically significant (0.05).Girls learnt better than boys. School classes that have better pre-knowledge about science before a visit to a science center learnt worse than other classes having less pre-knowledge. Girls and boys interact with a science center in different ways. Science center is playing important role as a science communicator.

Citizens and Contemporary Science Ways to dialogue in science centre contexts.

The current paper presents a study conducted at At-Bristol Science Centre, UK. It is a front-end evaluation for the “Live Science Zone” at At-Bristol, which will be built during the autumn of 2004. It will provide a facility for programmed events and shows, non-programmed investigative activities and the choice of passive or active exploration of current scientific topics. The main aim of the study is to determine characteristics of what kind of techniques to use in the Live Science Zone. The objectives are to explore what has already been done at At-Bristol, and what has been done at other science centres, and to identify successful devices. The secondary aim is mapping what sorts of topics that visitors are actually interested in debating. The methods used in the study are deep qualitative interviews with professionals working within the field of science communication in Europe and North America, and questionnaires answered by visitors to At-Bristol. The results show that there are some gaps between the intentions of the professionals and the opinions of the visitors, in terms of opportunities and willingness for dialogue in science centre activities. The most popular issue was Future and the most popular device was Film.

Tapping into Floor Staff: Using the knowledge of floor staff to conduct formative evaluations of exhibits in a Canadian science centre

Most science centres in Canada employ science-educated floor staff to motivate visitorsto have fun while enhancing the educational reach of the exhibits. Although bright andsensitive to visitors’ needs, floor staff are rarely consulted in the planning,implementation, and modification phases of an exhibit. Instead, many developmentteams rely on costly third-party evaluations or skip the front-end and formativeevaluations all together, leading to costly errors that could have been avoided. This studywill seek to reveal a correlation between floor staff’s perception of visitors’ interactionswith an exhibit and visitors’ actual experiences. If a correlation exists, a recommendationcould be made to encourage planning teams to include floor staff in the formative andsummative evaluations of an exhibit. This is especially relevant to science centres withlimited budgets and for whom a divide exists between floor staff and management.In this study, a formative evaluation of one exhibit was conducted, measuring both floorstaff’s perceptions of the visitor experience and visitors’ own perceptions of the exhibit.Floor staff were then trained on visitor evaluation methods. A week later, floor staff andvisitors were surveyed a second time on a different exhibit to determine whether anincrease in accuracy existed.The training session increased the specificity of the motivation and comprehensionresponses and the enthusiasm of the staff, but not their ability to predict observedbehaviours with respect to ergonomics, learning indicators, holding power, and successrates. The results revealed that although floor staff underestimated visitors’ success ratesat the exhibits, staff accurately predicted visitors’ behaviours with respect to holdingpower, ergonomics, learning indicators, motivation and comprehension, both before andafter the staff training.

Strategic alliances in a town centre : Stakeholder’s perceptions of property owner’s role

In order for town centres to manage increased competition in retailing, co-operation between stakeholders in a strategic alliance has become more important. A typical set of stakeholders in a strategic alliance for strengthening retailingare retailers, local authorities and property owners. The roles of retailer’sand local authorities’ are well researched. However, the role of property owners is not. The aim of this paper seeks to unfold the role of property owners in a strategic alliance. This is a case study of a medium-sized town in which semi-structured interviews with different stakeholders were conducted. In the chosen town there is a TCM alliance co-operation at work. The above mentioned stakeholders are possible members in an alliance. The case studied shows a fragmented property owner market with no dominant property owner, as it is in many medium-sized towns. Our study shows that many stakeholders look at the role of property owners as crucial for town centre development. However, property owners do not see that they can significantly contribute to or benefit from the development.The main reasons for this opinion are that they consider themselves as not having enough resources or the capability to influence the town development.

Occurrence of fungi in water used at a haemodialysis centre

Aims: The aim of this study was to identify and determine the diversity, occurrence and distribution of fungi in water used at a haemodialysis centre.Methods and Results: Samples in the hydraulic circuit for the distribution of the water, dialysate samples and samples of sterilization solution from dialysers were collected over a 3-month period, and 500 ml of each sample was filtered through membranes. All together 116 isolates of fungi were recovered from 89% of all water samples collected inside the haemodialysis unit, with prevalence of moulds in tap water samples and of yeasts in dialysate samples. Fusarium spp. was the most abundant genus found, whereas Candida parapsilosis was the predominant yeast species.Conclusions: This study demonstrated that various fungi were present in the water system. These data suggest the inclusion of the detection and quantification of fungi in the water of haemodialysis.Significance and Impact of the Study: The recovery of fungi from aqueous haemodialysis environments implies a potential risk for haemodialysis patients and indicates the need for continuous maintenance and monitoring. Further studies on fungi in haemodialysis water systems are required to investigate the organism ability to persist, their role in biofilm formation and their clinical significance.

Isolation and isoenzyme characterization of Leishmania (Viannia) braziliensis from a case of human cutaneous leishmaniasis in northeast centre of the state of São Paulo

The diagnosis of human cutaneous leishmaniasis in small towns is sometimes made without the species identification of the Leishmania, even in areas without previous epidemiological surveys. Here we report the isolation of a Leishmania strain from a patient of Rincão, state of São Paulo, that was identified by isoenzyme characterization as L. (Viannia) braziliensis. Sand fly collections were made in the area where the patient live in order to investigate the likely vector species.

Influences of the load centre of gravity on heavy vehicle acceleration

The aim of this paper is to analyse the influence of the load centre of gravity on heavy vehicle acceleration. This analysis is done through a method in which a vehicle centre of gravity map is used. A model for the driving force is presented for bus, truck and tractor-semi trailer combinations. The proposed model takes into consideration the resistance forces (drag, rolling resistance, translation and rotation acceleration, climbing resistance) and the 4 X 2 traction system. The positions of the vehicle centre of gravity as a function of the position of the load centre of gravity are determined. The vehicle acceleration is calculated based on the position of the load centre of gravity. This study analyses the acceleration of one of the Mercedes-Benz do Brasil tractor-semitrailer vehicle. A comparison of the acceleration for different maximum adhesion coefficients and ramps are presented, showing new results. An example showing the variations of the load centre of gravity position with the acceleration time and distance is provided. The load centre of gravity position is important for vehicle safety and the efficiency and economy in the transportation of the load.