Varistor property of n‐BaTiO3 based current limiters

Highly stable varistor (voltage-limiting) property is observed for ceramics based on donor doped (Ba1-xSrx)Ti1-yZryO3 (x < 0.35, y < 0.05), when the ambient temperature (T(a)) is above the Curie point (T(c)). If T(a) < T(c), the same ceramics showed stable current-limiting behavior. The leakage current and the breakdown voltage as well as the nonlinearity coefficient (alpha = 30-50) could be varied with the T(c)-shifting components, the grain boundary layer modifiers and the post-sintering annealing. Analyses of the current-voltage relations show that grain boundary layer conduction at T(a) < T(c) corresponds to tunneling across asymmetric barriers formed under steady-state joule heating. At T(a) > T(c), trap-related conduction gives way to tunneling across symmetric barriers as the field strength increases.

Oral health, smoking and adolescence

The present cross-sectional study examined the effect of smoking on oral health in a birth cohort of 15 to 16-year-old Finnish adolescents. The hypothesis was that oral health parameters were poorer among smoking than non-smoking subjects and that a tobacco intervention program could be effective among the adolescents. The study was conducted in the Kotka Health Center, Kotka, Finland. Altogether 501 out of 545 subjects (15- to 16-year-old boys [n = 258] and girls [n = 243]) were clinically examined in 2004 and 2005. The sample frame was a birth cohort of all subjects in 1989 and 1990, living in Kotka. A structured questionnaire was also filled in by the participants to record their general health and health habits, such as smoking, tooth brushing, and medication used. The participants were classified into nonsmokers, current smokers, and former smokers. Subgingival pooled plaque samples were taken and stimulated salivary samples were also collected. The subjects were asked from which of seven professional groups (doctors, school nurses, dental nurses, general nurses, dentists, teachers and media professionals) they would prefer to receive information about tobacco. The two most popular groups they picked up were dentists and school nurses. Current smokers (n=127) were then randomly assigned into three groups: the dentist group (n =44), the school-nurse group (n =42), and the control group (n =39). The intervention was based on a national recommendation of evidence based guidelines by The Finnish Medical Society Duodecim ( 5A counseling system). Two months after the intervention, a second questionnaire was sent to the smokers in the intervention groups. Smoking cessation, smoking quantity per week, and self-rated addiction for smoking (SRA) were recorded. The results were analyzed using the R-statistical program. The results showed that 15% of the subjects had periodontitis. Smokers (25%) had more periodontitis than non-smokers (66%) (p < 0.001). Smoking boys (24%) also had more caries lesions than non-smokers (69%) (p < 0.001), and they brushed their teeth less frequently than non-smokers. Smoking significantly impaired periodontal health of the subjects, even when the confounding effects of plaque and tooth brushing were adjusted. Smoking pack-years, intensified the effects of smoking. Periodontal bacteria Prevotella nigrescens, Prevotella intermedia, Tannerella forsythia and Treponema denticola were more frequently detected among the smokers than non-smokers, especially among smoking girls. Smoking significantly decreased the values of both the salivary periodontal biomarkers MMP-8 (p=0.04) and PMN elastase (p=0.02) in boys. The effect was strengthened by pack years of smoking (MMP-8 p=0.04; elastase p0.01). Of those who participated in the intervention, 19 % quit smoking. The key factors associated with smoking cessation were best friend`s influence, nicotine dependence and diurnal type. When the best friend was not a smoker, the risk ratio (RR) of quit smoking after the intervention was 7.0 (Cl 95% 4.6 10.7). Of the diurnal types, the morning people seemed to be more likely to quit (RR 2.2 [Cl 95% 1.4 3.6]). Nicotine dependence also elicited an opposite effect: those who scored between 3 and 5 dependence scores were less likely to quit. In conclusion, smoking appears to be a major etiological risk factor for oral health. However, the early signs of periodontal disease were mild in the subjects studied. Based on the opinions of the adolescent s, dental professionals may have a key position in their smoking cessation. The harmful effects of smoking on oral health could be used in counselling. Best friend`s influence, nicotine dependence and diurnal type, all factors associated with smoking cessation, should be taken more carefully into account in the prevention programs for adolescents.

A Resonant Integrator Based PLL and AC Current Controller for Single Phase Grid Connected PWM-VSI

Grid connected PWM-VSIs are being increasingly used for applications such as Distributed Generation (DG), power quality, UPS etc. Appropriate control strategies for grid synchronisation and line current regulation are required to establish such a grid interconnection and power transfer. Control of three phase VSIs is widely reported in iterature. Conventionally, dq control in Synchronous Reference Frame(SRF) is employed for both PLL and line current control where PI-controllers are used to track the DC references. Single phase systems do not have defined direct (d) and quadrature (q) axis components that are required for SRF transformation. Thus, references are AC in nature and hence usage of PI controllers cannot yield zero steady state errors. Resonant controllers have the ability to track AC references accurately. In this work, a resonant controller based single phase PLL and current control technique are being employed for tracking grid frequency and the AC current reference respectively. A single phase full bridge converter is being operated as a STATCOM for performance evaluation of the control scheme.

Analysis of co-current hydraircooling of food products in bulk

A mathematical model is developed to describe the hydraircooling process when the water and air are flowing in the same direction. The governing equations for the simultaneous heat and mass transfer are solved using finite-difference numerical methods. The half cooling time of the food products is correlated as a function of the dimensionless process parameters. It is observed that a process time of approximately double the half cooling time will result in the food products attaining almost a steady state. The process times of the bulk hydraircooling process and the bulk air precooling process are compared.

Constructing and negotiating entrepreneurial agency : A social psychological approach to entrepreneurship discourse in the farm context

Entrepreneurship, understood as the autonomous, effective pursuit of opportunities regardless of resources, is currently subject to a multitude of interests, expectations, and facilitation efforts. On the one hand, such entrepreneurial agency has broad appeal to individuals in Western market democracies and resonates with their longing for an autonomous, personally tailored, meaningful, and materially rewarding way of life. On the other hand, entrepreneurship represents a tempting and increasingly popular means of governance and policy making, and thus a model for the re-organization of a variety of societal sectors. This study focuses on the diffusion and reception of entrepreneurship discourse in the context of farming and agriculture, where pressures to adopt entrepreneurial orientations have been increasingly pronounced while, on the other hand, the context of farming has historically enjoyed state protection and adhered to principles that seem at odds with aspects of individualistic entrepreneurship discourse . The study presents an interpretation of the psychologically and politically appealing uses of the notion of entrepreneurial agency , reviews the historical and political background of the current situation of farming and agriculture with regard to entrepreneurship, and examines their relationships in four empirical studies. The study follows and develops a social psychological, situated relational approach that guides the qualitative analyses and interpretations of the empirical studies. Interviews with agents from the farm sector aim to stimulate evaluative responses and comments on the idea of entrepreneurship on farms. Analysis of the interview talk, in turn, detects the variety of evaluative responses and argumentative contexts with which the interviewees relate themselves to the entrepreneurship discourse and adopt, use, resist, or reject it. The study shows that despite the pressures towards entrepreneurialism, the diffusion of entrepreneurship discourse and the construction of entrepreneurial agency in farm context encounter many obstacles. These obstacles can be variably related to aspects dealing with the individual agent, the action situation, the characteristics of the action itself, or to the broader social, institutional and cultural context. Many aspects of entrepreneurial agency, such as autonomy, personal initiative and achievement orientation, are nevertheless familiar to farmers and are eagerly related to one s own farming activities. The idea of entrepreneurship is thus rarely rejected outright. The findings highlight the relational and situational preconditions for the construction of entrepreneurial agency in the farm context: When agents demonstrate entrepreneurial agency, they do so by drawing on available and accessed relational resources characteristic of their action context. Likewise, when agents fail or are reluctant to demonstrate entrepreneurial agency, they nevertheless actively account for their situation and demonstrate personal agency by drawing on the relational resources available to them.

Coated pits,endosome CURLing and intracellular receptor--ligand trafficking

In mediating endocytosis of extracellular macromolecules; the major mechanism in which cells ingest nutrients, degrade hormones and maintain the protein and lipid compositions of their organelle membrane, the cell surface receptors encounter 'coated pits', migrate continuously from one organelle to another, deliver the 'cargo' and often recycle back to the cell surface. This article is an attempt to give an account of the recent advances in our understanding of the molecular events involved in the 'round trip itinerary' of cell surface receptors.

Indian Ocean Dipole: Processes and impacts

Equatorial Indian Ocean is warmer in the east, has a deeper thermocline and mixed layer, and supports a more convective atmosphere than in the west. During certain years, the eastern Indian Ocean becomes unusually cold, anomalous winds blow from east to west along the equator and southeastward off the coast of Sumatra, thermocline and mixed layer lift up and the atmospheric convection gets suppressed. At the same time, western Indian Ocean becomes warmer and enhances atmospheric convection. This coupled ocean-atmospheric phenomenon in which convection, winds, sea surface temperature (SST) and thermocline take part actively is known as the Indian Ocean Dipole (IOD). Propagation of baroclinic Kelvin and Rossby waves excited by anomalous winds, play an important role in the development of SST anomalies associated with the IOD. Since mean thermocline in the Indian Ocean is deep compared to the Pacific, it was believed for a long time that the Indian Ocean is passive and merely responds to the atmospheric forcing. Discovery of the IOD and studies that followed demonstrate that the Indian Ocean can sustain its own intrinsic coupled ocean-atmosphere processes. About 50% percent of the IOD events in the past 100 years have co-occurred with El Nino Southern Oscillation (ENSO) and the other half independently. Coupled models have been able to reproduce IOD events and process experiments by such models – switching ENSO on and off – support the hypothesis based on observations that IOD events develop either in the presence or absence of ENSO. There is a general consensus among different coupled models as well as analysis of data that IOD events co-occurring during the ENSO are forced by a zonal shift in the descending branch of Walker cell over to the eastern Indian Ocean. Processes that initiate the IOD in the absence of ENSO are not clear, although several studies suggest that anomalies of Hadley circulation are the most probable forcing function. Impact of the IOD is felt in the vicinity of Indian Ocean as well as in remote regions. During IOD events, biological productivity of the eastern Indian Ocean increases and this in turn leads to death of corals over a large area.Moreover, the IOD affects rainfall over the maritime continent, Indian subcontinent, Australia and eastern Africa. The maritime continent and Australia suffer from deficit rainfall whereas India and east Africa receive excess. Despite the successful hindcast of the 2006 IOD by a coupled model, forecasting IOD events and their implications to rainfall variability remains a major challenge as understanding reasons behind an increase in frequency of IOD events in recent decades.

Nature of chemistry in the national frame curricula for upper secondary education in Finland, Norway and Sweden

The aim of this study was to discover how current chemistry syllabi in the frame curricula for up- per secondary education in three Nordic countries (Finland, Norway, and Sweden) take into account topics related to the nature of chemistry. By qualitative content analysis, the statements related to the nature of chemistry were divided into categories. Conclusions and implications for improving the frame curricula under study were made by comparing results with research into the nature of science. Chemistry syllabi from the Nordic frame curricula analyzed take into account the aims related to the nature of chemistry in a very similar manner. The ideas that should be made more explicit in all of the analyzed curricula are: i) the limits of the chemical models and theories, ii) the relationship between chemistry and other natural sciences, iii) the importance of creativity in chemical research, iv) the concepts of evidence in science texts, v) the social nature of chemical research, and vi) chemistry as a technological practice.

Effect of the pyrethroid insecticide fenvalerate on sodium current of rat dorsal root ganglion neuron

Fenvalerate is a widely used pyrethroid insecticide. The report presents our findings on the effect of fenvalerate on isolated whole-cell sodium currents in single rat dorsal root ganglionic neurons in culture, studied with patch-clamp technique. Fenvalerate decreased the amplitude of whole-cell sodium current and slowed the inactivation and tail current kinetics.

Uutta, vanhaa ja lainattua : Tampereen Kaupunkilähetyksen kristillissosiaalisen työn asemoituminen hyvinvointivaltion rakentumisessa vuosina 1939−1973

The main purpose of this study was to provide a full account of the Christian social work carried out at the Tampere City Mission (TCM) as well as the Missions sphere of operations from the Second World War to the early 1970s, comprising a period of significant change. The study consists of charting the processes of change and connections within the activities of the TCM and how examining these were linked to the general tendencies of the period, in lay work, social work, professionalization and the representation of gender. The positioning of the activities is described on the basis of these tendencies. The main sources for the study were the archives of the Mission, for example the minutes of meetings, correspondences as well as annual reports, and the archives of its partners, such as the City of Tampere, the Evangelical Lutheran parishes of Tampere and the State Welfare Administration. The archives of the Helsinki, Turku and Stockholm Missions supplied comparison reference and other material. In particular, social welfare and Christian social work technical journals of were used as printed sources. The principal method used was the genetic method of historiology. The research subject was also evaluated from the point of view of third sector research in addition to that of professionalization studies and gender studies. By the beginning of the research period, the TCM had turned more and more dedicatedly into a multipurpose social service organization maintaining social services such as old people s homes and children´s homes. This development continued, even though new areas of activity emerged and older ones fell into disuse. Social innovations sprang up, marriage counseling being one of them. On the national level, the TCM pioneered the provision of sheltered industrial work for intellectually disabled persons as well as housing services for them. As new activities were initiated, they overlapped with the established ones, and the TCM handed some of its child protection functions over to the municipality, in accordance with the current adaptation theory. The use of its own property to produce ever-changing social services may be the reason why the association s work continued on with vitality. Functional networks and political aid in the field of social services also bolstered the association. As in other Nordic countries, nonprofit organizations served as partners rather than competitors, with the State establishing institutional welfare arrangements. In the 1960s the municipal takeover of social services impacted the TCM activities. Rules for government subsidies and municipal allowances were not well established; hence these funds were not easily available, making improvements difficult. The TCM was a community in which women had a relatively strong position and an opportunity to make a difference. Female staff were reasonably equal to men, and women worked as heads of a several institutions. Care work employed a number of men, which went against the traditional segregation of labour between the sexes. The TCM s operations were from early on very professionalized, and were developed with particular care. Keywords: Christian social work, third sector, professionalization, gender

Field-dependent changeover from current-to voltage-limiting characteristics by non-linear n-type BaTiO3 ceramics

Non-linear resistors having current-limiting capabilities at lower field strengths, and voltage-limiting characteristics (varistors) at higher field strengths, were prepared from sintered polycrystalline ceramics of (Ba0.6Sr0.4)(Ti0.97Zr0.03)O3+0.3 at % La, and reannealed after painting with low-melting mixtures of Bi2O3 + PbO +B2O3. These types of non-linear characteristics were found to depend upon the non-uniform diffusion of lead and the consequent distribution of Curie points (T c) in these perovskites, resulting in diffuse phase transitions. Tunnelling of electrons across the asymmetric barrier at tetragonak-cubic interfaces changes to tunnelling across the symmetric barrier as the cubic phase is fully stabilized through Joule heating at high field strengths. Therefore the current-limiting characteristics switch over to voltage-limiting behaviour because tunnelling to acceptor-type mid-bandgap states gives way to band-to-band tunnelling.

Low frequency oscillations in power systems: A physical account and adaptive stabilizers

This paper presents a physical explanation of the phenomenon of low frequency oscillations experienced in power systems. A brief account of the present practice of providing fixed gain power system stabilizers (PSS) is followed by a summary of some of the recent design proposals for adaptive PSS. A novel PSS based on the effort of cancelling the negative damping torque produced by the automatic voltage regulator (AVR) is presented along with some recent studies on a multimachine system using a frequency identification technique.

Current State of Domestic Concealed Wiring Practices in Bangalore, India

In a modernising world, building and construction trends in recent urban centres such as Bangalore, set precedence for developments in other urban centres of the country. Under such conditions, evaluating the current state of building practices could prove useful for identifying the likely nature of nationwide building trends. This paper comprises a study to evaluate the current state of domestic concealed wiring practices in the context of a modern urban centre area in India. Presently, concealed wiring is the predominant wiring method adopted for residences, both bungalows and apartments. A modern residential block in the city of Bangalore (India) was chosen as the study area. The study included extensive interaction and surveys amongst residents, professionals (architects and engineers) and site personnel (contractors and electricians). In addition, the study also included site verification on the state of wiring practices in the residential block. The study indicates that while aesthetics was the prime reason that dictated the choice of concealed wiring, its effectiveness as an appropriate and safe wiring method is severely compromised. Details of the study, results and recommendations are presented in this paper.