884 resultados para DTN,Opportunistic Routing,Contact Graph Routing,Opportunistic Contact Graph Routing,ION
Resumo:
S. C. Wright, A. Aron, T. McLaughlin-Volpe, and S. A. Ropp (1997) proposed that the benefits associated with cross-group friendship might also stem from vicarious experiences of friendship. Extended contact was proposed to reduce prejudice by reducing intergroup anxiety, by generating perceptions of positive ingroup and outgroup norms regarding the other group, and through inclusion of the outgroup in the self. This article documents the first test of Wright et al.'s model, which used structural equation modeling among two independent samples in the context of South Asian-White relations in the United Kingdom. Supporting the model, all four variables mediated the relationship between extended contact and outgroup attitude, controlling for the effect of direct contact. A number of alternative models were ruled out, indicating that the four mediators operate concurrently rather than predicting one another.
Resumo:
The contact hypothesis states that, under the right conditions, contact between members of different groups leads to more positive intergroup relations. The authors track recent trends in contact theory to the emergence of extended, or indirect, forms of contact. These advances lead to an intriguing proposition: that simply imagining intergroup interactions can produce more positive perceptions of outgroups. The authors discuss empirical research supporting the imagined contact proposition and find it to be an approach that is at once deceptively simple and remarkably effective. Encouraging people to mentally simulate a positive intergroup encounter leads to improved outgroup attitudes and reduced stereotyping. It curtails intergroup anxiety and extends the attribution of perceivers' positive traits to others. The authors describe the advantages and disadvantages of imagined contact compared to conventional strategies, outline an agenda for future research, and discuss applications for policymakers and educators in their efforts to encourage more positive intergroup relations.
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Adoption policy in the UK emphasizes its role in providing secure, permanent relationships to children in care who are unable to live with their birth families. Adoptive parents are crucial in providing this life-long, stable experience of family for these vulnerable children. This paper explores the experience of adoptive parenthood in the context of changes to adoptive kinship relationships brought about by new, unplanned contact with birth family during their child's middle adolescence. This contact was initiated via informal social networks and/or social media, with older birth siblings instrumental in negotiating renewed relationships. The contact precipitated a transition in adoptive family life resulting in emotional challenges and changes in parent/child relationships, which were experienced as additional to the normative transitions expected during adolescence. Parental concern as a dominant theme was founded in the child and birth sibling's stage of adolescence, coupled with constraints on adoptive parenthood imposed by the use of social media, by perceived professional attitudes and by parental social cognitions about the importance of birth ties. Adoptive parents' accounts are interpreted with reference to family life-cycle theory and implications are suggested for professional support of adoptive kinship relationships.
Resumo:
One approach to tackling problems of division in society has been to promote collaboration and engagement between schools separated on ethno-religious lines. Based on some variant of contact theory, the received wisdom is that inter-group encounters can contribute to prejudice reduction and promote more harmonious relationships. Evidence to support this analysis is convincing; however, relatively little is known about the environmental factors that impede or enhance the potential for contact in different contexts. The importance of understanding such factors is underscored in divided jurisdictions, where separate education has been linked to the perpetuation of division and hostility. This paper adopts a qualitative approach to exploring the impact of two inter-school initiatives in Northern Ireland. The projects are located in contrasting socio-political and demographic environments, and research findings point to very different contact outcomes for participants in each. Seemingly relevant factors include the degree of congruence between school and community norms and values, the opportunity to develop relationships outside the school context, the relationships developed between the schools and local communities and the historical, political and social referents used by individuals to navigate the contact experience. The paper concludes with some reflections on factors that may help foster social harmony and on potential policy implications of the findings.
Resumo:
Purpose: The purpose of this study was to describe the outcome of patients with filtering blebs who were fit with contact lenses. Methods: We retrospectively studied patients with filtering blebs secondary to glaucoma or cataract surgery who were fit with contact lenses. Eight eyes from seven patients were identified. Results: Five patients (six eyes) were fit with gas permeable contact lenses and two patients (two eyes) were fit with soft contact lenses. Successful fits were achieved in all patients. No complications were observed after a mean follow-up of 64.6±28.5 months. Conclusions: No significant complications were recorded in our series of patients with filtering blebs who were fit with contact lenses. We think that when indications for fitting contact lenses are justified, patients with filtering blebs are acceptable candidates for contact lens use. However, adequate selection of cases, careful contact lens fitting, patient education, and close follow-up are necessary.
Resumo:
Purpose: The purpose of this study was to evaluate the outcome of patients with healed moderate to severe contact lens-associated corneal infectious ulcers who were re-fit with contact lenses. Methods: We retrospectively studied patients who were fit with contact lenses on our service and who had had moderate to severe corneal infectious ulcers associated with previous contact lens use. Six patients were included in the study. Results: Gas permeable contact lenses were fit in five patients, and a soft contact lens was fit in one patient. Successful fit was achieved in all cases and visual acuities were equal to or better than 20/30 in all patients. No significant complications were observed after a mean follow-up of 23 months (range, 6-45 months). Conclusion: In this small series of patients with a history of moderate to severe contact-lens related infectious keratitis, no complications were observed after contact lenses were refit. Contact lens wear in patients with a history of infectious keratitis may be safe and useful in order to achieve visual rehabilitation.
Resumo:
Purpose: The purpose of this study was to evaluate the contamination of used disposable soft contact lenses with Acanthamoeba. Methods: We evaluated 51 consecutive disposable soft contact lens wearers in a prospective study. Before their check-up visits, patients were offered a free new contact lens in exchange for donating their old one. The used contact lenses (n=102) were then removed and placed in culture medium for Acanthamoeba. We subsequently investigated patterns of wear and hygiene habits. Results: The mean age of this population was 32.6±11.0 years. The average time of disposable soft contact lens wear was 13.7 hours per day. The contact lenses were disinfected daily with commercial solutions. Twenty-five (49.0%) subjects did not clean their lens cases properly. Acanthamoeba was not isolated from any of the 102 lenses. Conclusions: There were no cases of Acanthamoeba contamination in a small population of disposable soft contact lens wearers who regularly disinfected their lenses with standard commercially available contact lens solutions.
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We previously described a Multilocus Sequence Typing (MLST) scheme based on eight genes that facilitates population genetic and evolutionary analysis of P. acnes. While MLST is a portable method for unambiguous typing of bacteria, it is expensive and labour intensive. Against this background, we now describe a refined version of this scheme based on two housekeeping (aroE; guaA) and two putative virulence (tly; camp2) genes (MLST) that correctly predicted the phylogroup (IA, IA, IB, IC, II, III), clonal complex (CC) and sequence type (ST) (novel or described) status for 91% isolates (n = 372) via cross-referencing of the four gene allelic profiles to the full eight gene versions available in the MLST database (http://pubmlst.org/pacnes/). Even in the small number of cases where specific STs were not completely resolved, the MLST method still correctly determined phylogroup and CC membership. Examination of nucleotide changes within all the MLST loci provides evidence that point mutations generate new alleles approximately 1.5 times as frequently as recombination; although the latter still plays an important role in the bacterium's evolution. The secreted/cell-associated 'virulence' factors tly and camp2 show no clear evidence of episodic or pervasive positive selection and have diversified at a rate similar to housekeeping loci. The co-evolution of these genes with the core genome might also indicate a role in commensal/normal existence constraining their diversity and preventing their loss from the P. acnes population. The possibility that members of the expanded CAMP factor protein family, including camp2, may have been lost from other propionibacteria, but not P. acnes, would further argue for a possible role in niche/host adaption leading to their retention within the genome. These evolutionary insights may prove important for discussions surrounding camp2 as an immunotherapy target for acne, and the effect such treatments may have on commensal lineages. © 2013 McDowell et al.
Resumo:
Question: How parallel is adaptive evolution when it occurs from different genetic backgrounds? Background: Divergent evolutionary lineages of several post-glacial fish species including the threespine stickleback are found together in Ireland. Goals: To investigate the morphological diversity of stickleback populations in Ireland and assess whether morphology evolved in parallel between evolutionary lineages. Methods: We sampled stickleback from lake, river, and coastal habitats across Ireland. Microsatellite and mitochondrial DNA data revealed evolutionary history. Geometric morphometrics and linear trait measurements characterized morphology. We used a multivariate approach to quantify parallel and non-parallel divergence within and between lineages. Results: Repeated evolution of similar morphologies in similar habitats occurred across Ireland, concordant with patterns observed elsewhere in the stickleback distribution. A strong pattern of habitat-specific morphology existed even among divergent lineages. Furthermore, a strong signal of shared morphological divergence occurred along a marine-freshwater axis. Evidently, deterministic natural selection played a more important role in driving freshwater adaptation than independent evolutionary history. © 2013 Mark Ravinet.