Transport of Water and Gases through EVA/PVC blend films – Permeation and DSC investigations.

The transport of water vapor and gases (oxygen and carbon dioxide) through poly(ethylene-co-vinyl acetate) (EVA) films of different VA content, poly(vinylchloride) (PVC) and EVA/PVC blend films, was analysed from permeation measurements. A plasticization effect of water on the material was observed for EVA films with more than 19% wt. of VA content and for the EVA/PVC blends, while for gas permeation practically all the experimental curves are characterized by a constant diffusion coefficient, whatever the VA content of the copolymer used. The increase in water absorption with the VA content leads to a steady increase in the water permeability of the EVA copolymers. By mixing the glassy PVC polymer with the EVA copolymer (in a rubbery state) reduced water and gas permeability is observed, resulting mainly from the decrease of the diffusivity due to the low segment mobility of the dense PVC material able to create hydrogen bonds between the hydrogen atoms and the Cl-substituted carbon of PVC with VA carbonyls. Compared to EVA copolymers, the EVA/PVC blends with equivalent VA contents are better in terms of selectivity

Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

Nonlinear fractional differential equations in nonreflexive Banach spaces and fractional calculus

The aim of this paper is to correct some ambiguities and inaccuracies in Agarwal et al. (Commun. Nonlinear Sci. Numer. Simul. 20(1): 59-73, 2015; Adv. Differ. Equ. 2013: 302, 2013, doi:10.1186/1687-1847-2013-302) and to present new ideas and approaches for fractional calculus and fractional differential equations in nonreflexive Banach spaces

Retention of health workers in Malawi: perspectives of health workers and district management

<p>Abstract</p> <p>Background</p> <p>Shortage of human resources is a major problem facing Malawi, where more than 50% of the population lives in rural areas. Most of the district health services are provided by clinical health officers specially trained to provide services that would normally be provided by fully qualified doctors or specialists. As this cadre and the cadre of enrolled nurses are the mainstay of the Malawian health service at the district level, it is important that they are supported and motivated to deliver a good standard of service to the population. This study explores how these cadres are managed and motivated and the impact this has on their performance.</p> <p>Methods</p> <p>A quantitative survey measured health workers' job satisfaction, perceptions of the work environment and sense of justice in the workplace, and was reported elsewhere. It emerged that health workers were particularly dissatisfied with what they perceived as unfair access to continuous education and career advancement opportunities, as well as inadequate supervision. These issues and their contribution to demotivation, from the perspective of both management and health workers, were further explored by means of qualitative techniques.</p> <p>Focus group discussions were held with health workers, and key-informant interviews were conducted with members of district health management teams and human resource officers in the Ministry of Health. The focus groups used convenience sampling that included all the different cadres of health workers available and willing to participate on the day the research team visited the health facility. The interviews targeted district health management teams in three districts and the human resources personnel in the Ministry of Health, also sampling those who were available and agreed to participate.</p> <p>Results</p> <p>The results showed that health workers consider continuous education and career progression strategies to be inadequate. Standard human resource management practices such as performance appraisal and the provision of job descriptions were not present in many cases. Health workers felt that they were inadequately supervised, with no feedback on performance. In contrast to health workers, managers did not perceive these human resources management deficiencies in the system as having an impact on motivation.</p> <p>Conclusion</p> <p>A strong human resource management function operating at the district level is likely to improve worker motivation and performance.</p

Novel polyomaviruses in mammals from multiple orders and reassessment of polyomavirus evolution and taxonomy

As the phylogenetic organization of mammalian polyomaviruses is complex and currently incompletely resolved, we aimed at a deeper insight into their evolution by identifying polyomaviruses in host orders and families that have either rarely or not been studied. Sixteen unknown and two known polyomaviruses were identified in animals that belong to 5 orders, 16 genera, and 16 species. From 11 novel polyomaviruses, full genomes could be determined. Splice sites were predicted for large and small T antigen (LTAg, STAg) coding sequences (CDS) and examined experimentally in transfected cell culture. In addition, splice sites of seven published polyomaviruses were analyzed. Based on these data, LTAg and STAg annotations were corrected for 10/86 and 74/86 published polyomaviruses, respectively. For 25 polyomaviruses, a spliced middle T CDS was observed or predicted. Splice sites that likely indicate expression of additional, alternative T antigens, were experimentally detected for six polyomaviruses. In contrast to all other mammalian polyomaviruses, three closely related cetartiodactyl polyomaviruses display two introns within their LTAg CDS. In addition, the VP2 of Glis glis (edible dormouse) polyomavirus 1 was observed to be encoded by a spliced transcript, a unique experimental finding within the Polyomaviridae family. Co-phylogenetic analyses based on LTAg CDS revealed a measurable signal of codivergence when considering all mammalian polyomaviruses, most likely driven by relatively recent codivergence events. Lineage duplication was the only other process whose influence on polyomavirus evolution was unambiguous. Finally, our analyses suggest that an update of the taxonomy of the family is required, including the creation of novel genera of mammalian and non-mammalian polyomaviruses.info:eu-repo/semantics/publishedVersio

Improving motivation among primary health care workers in Tanzania: a health worker perspective

In Tanzania access to urban and rural primary health care is relatively widespread, yet there is evidence of considerable bypassing of services; questions have been raised about how to improve functionality. The aim of this study was to explore the experiences of health workers working in the primary health care facilities in Kilimanjaro Region, Tanzania, in terms of their motivation to work, satisfaction and frustration, and to identify areas for sustainable improvement to the services they provide. The primary issues arising pertain to complexities of multitasking in an environment of staff shortages, a desire for more structured and supportive supervision from managers, and improved transparency in career development opportunities. Further, suggestions were made for inter-facility exchanges, particularly on commonly referred cases. The discussion highlights the context of some of the problems identified in the results and suggests that some of the preferences presented by the health workers be discussed at policy level with a view to adding value to most services with minimum additional resources

Some psychosocial and cultural factors in the Arab-Israeli conflict: a review of the literature

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66497/2/10.1177_002200277201600210.pd

Hundreds of variants clustered in genomic loci and biological pathways affect human height

Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.