Arsenic is found in drinking waters in many countries and since maximum allowable concentration is as low as 10 &micro / g/L, there are many research efforts to separate it from water. Membrane methods are used more and more widely in separation operations in recent years. Arsenic is mainly present in water as arsenite [As(III)] and arsenate [As(V)]. As pH of water changes, molecular formulas of As(III) and As(V) change. In this study, the performance of different ultrafiltration membranes for arsenic removal from water was investigated at different pH values, different feed concentrations and presence of other anions (SO42-, HPO42-, NO3-, Cl-). Donnan exclusion effect on separation was discussed since distribution of arsenite and arsenate anions change in water due to change in pH of the solution. Experiments were conducted via batch and continuous modes. For continuous ultrafiltration experiments, 30 kDa of polysulfone and 20 kDa of polyether sulfone membranes were used. Batch ultrafiltration experiments were performed with the usage of 3 kDa of regenerated cellulose membrane. Higher retention values for As(V) were obtained compared to retention values of As(III). When membranes&rsquo / performances were investigated, it was seen that highest As(V) removal was observed with the usage of polysulfone membrane. Increase in feed concentration and presence of other anions caused decrement in separation. Hydride Generation Atomic Absorption Spectrometry was used to perform analyses. Hydride generator part was designed, constructed and optimized to obtain reliable and accurate absorbance values.

A mobile ad hoc network consists of certain nodes that communicate only through wireless medium and can move arbitrarily. The key feature of a mobile ad hoc network is the mobility of the nodes. Because of the mobility, communication links form and disappear as nodes come into and go out of each other's communica- tion range. Mobile ad hoc networks are particularly useful in situations like disaster recovery and search, military operations, etc. Research on mobile ad hoc networks has drawn a huge amount of attention recently. The main challenges for mobile ad hoc networks are the sparse resources and frequent mobility. Most of the research work has been focused on the MAC and routing layer. In this work, we focus on distributed services for mobile ad hoc networks. These services will provide some fundamental functions in developing various applications for mobile ad hoc networks. In particular, we focus on the clock synchronization, connected dominating set, and k-mutual exclusion problems in mobile ad hoc networks.

Reproduction de : Thèse de doctorat : Sciences de l'éducation : Lyon 2 : 2002. / Titre provenant de l'écran-titre. Bibliogr.

Thèse de doctorat : Psychologie : Lyon 2 : 2001. / Titre provenant de l'écran-titre. Bibliogr.. Index.

Narkotika- och alkoholmissbruk är ett hälsoproblem i hela världen och nyktra missbrukare är en utsatt grupp i samhället. Vid missbruk är det inte bara intaget av narkotikan eller alkoholen som medför skada. Hela livssituationen kan bli drabbad, inte minst kontakten med vänner och familj. För att hålla sig nykter, återanpassa sig till samhället och leva ett hälsosamt liv finns det många faktorer som är betydelsefulla. Syftet med studien var därför att undersöka nyktra missbrukares upplevelser av socialt stöd, fritidsaktiviteter samt utanförskap och delaktighet i samhället. En empirisk kvalitativ studie har gjorts genom semistrukturerade intervjuer för att besvara syftet om upplevelser av dessa faktorer. Insamlad data har transkriberats och analyserats med hjälp av en kvalitativ innehållsanalys. Resultatet har kategoriserats och visade att nyktra missbrukare känner avsaknad av socialt stöd, hinder i att utföra fritidsaktiviteter samt utanförskap i samhället. En önskan om att kunna utöva intressen, ha bra vänner och känna en gemenskap fanns. Faktorerna upplevdes som viktiga för att bibehålla en nykterhet. / Drug and alcohol abuse is a health problem worldwide. Alcohol and drug abuse can effect ones entire life, sober abusers are a vulnerable group in the society. To stay sober, or come back to the society and live a healthy life, might be influenced by many factors. The aim of the study was to examine sober alcohol and drug abusers’ experiences of social support, leisure time activities, exclusion and participation in the society. A qualitative study with semi-structured interviews was used to address the aim of the study. The content analysis of four interviews showed that sober abusers experience the lack of social support. Furthermore, they encounter difficulties to participate in and experience alienation in society. The participants considered that social support, leisure activities, exclusion and participation in society was important to them. Finally, there was a desire from sober abusers to carry out interests of their own, and feel a sense of belonging to the community.

Toni Morrison's recovery of the African-American presence in her novels is uniquely tied to the space of the kitchen. The recovery of the African-American presence has been accomplished in various ways for various groups: historians, critics, authors, sociologists. They have named names, recalled incidents, and 'discovered' texts. Recovery has been accomplished by reconstructing culture through songs, storytelling, folklore and myth. Morrison establishes a connection between the space of the Garden that represents a white male empowered world in which African-American women have difficulty establishing power to a space of the kitchen where we see how well each character has been able to confront the public sphere (garden) and maintain her sense of self and a sense of empowerment. Each character's interiority is reflected in the activities and her relationship to the kitchen.

Being excluded should motivate pro-social behaviors. Yet, exclusion can incite aggressive and anti-social responses. Two studies were conducted to examine how frequent experiences of exclusion impact self-esteem, perceptions that exclusion is typical of social experiences, and anti-social behaviors. In Study 1, participants completed pre and post-measures of exclusion typicality and self-esteem and reported, over eight weeks, feelings of exclusion and state self-esteem. Results supported the hypotheses in that experiences feeling excluded have direct and indirect effects on state and trait self-esteem as well as on exclusion typicality. In Study 2, participants were exposed to an exclusion manipulation and subsequent aggressive and anti-social behaviors were assessed. Results were inconsistent with hypotheses that exclusion typicality and self-esteem would moderate responses to exclusion. Discussion focuses on the implications for a model of exclusion elicited anti-social behaviors.

Economic remittances are money transfers worldwide from migrants to their country of origin. This study aimed to examine which significance the remittance has for the sender. How do the senders describe their experiences of remittances, what strategies are used in the process of remitting and how has the migrants’ social and economic situation in the host country been affected by remitting? The issues were answered through six semi-structured interviews with remitting migrants. The theoretical approach consisted of the concepts transnational social space, reciprocity and social exclusion. The findings were that remittances had great value to the senders with both negative and positive outcomes. Strategies formed to live up to expectations to remit were group wise, long-term and practical. Remittances had an impact on choices regarding recreational activities, housing and employment. Our conclusion is that remitting is an important act to maintain the bond to the country of origin, despite economic and social sacrifices. Being a participant in dual social worlds in which social and economic conditions differ shapes the experienced requirement to remitt.  Remittance cannot be seen as a sole factor for placing senders in social exclusion, though it can limit the sender economically and socially.

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My essay is written from a basis of one of my own experiences were a child is perceived by us pedagogues as lonely and introverted, as well as having trouble socialising because of, what we can see, difficulties making himself understood verbally. I want to highlight how I as a pedagogue can respond to and strengthen children who are outside but still with the group, in a certain sense. I want to reflect on how we can deepen our understanding of these children and how we can facilitate for children who do not follow the norms of society when it comes to communication. I will analyse and draw conclusions with the help of theorists such as Jean Piaget and Lev Vygotskij and interpretations of these, but also look at it from a sociopsychological perspective as the interactions between people and environments play a large and distinctive role in preschool. The purpose of this essay is to enlighten how different we can see and experience situations in preschool. What can be seen as exclusion by an outsider does not necessarily have to be experienced that way by the person in question. Through my analysis I have gained attention to that we, through our individual understanding, interprete and judge other people's behaviour and actions based on our own experiences.