Combining hyaluronic acid with chitosan enhances gene delivery

The low gene transfer efficiency of chitosan-DNA polyplexes is a consequence of their high stability and consequent slow DNA release. The incorporation of an anionic polymer is believed to loosen chitosan interactions with DNA and thus promote higher transfection efficiencies. In this work, several formulations of chitosan-DNA polyplexes incorporating hyaluronic acid were prepared and characterized for their gene transfection efficiency on both HEK293 and retinal pigment epithelial cells. The different polyplex formulations showed morphology, size, and charge compatible with a role in gene delivery. The incorporation of hyaluronic acid rendered the formulations less stable, as was the goal, but it did not affect the loading and protection of the DNA. Compared with chitosan alone, the transfection efficiency had a 4-fold improvement, which was attributed to the presence of hyaluronic acid. Overall, our hybrid chitosan-hyaluronic acid polyplexes showed a significant improvement of the efficiency of chitosan-based nonviral vectors in vitro, suggesting that this strategy can further improve the transfection efficiency of nonviral vectors.Fundacao para a Ciencia e Tecnologia [SFRH/BD/52424/2013]; Marie Curie Reintegration Grant [PIRG-GA-2009-249314

Chitosan-Hyaluronic acid hybrid vectors for retinal gene therapy

info:eu-repo/semantics/publishedVersio

Comparing alternative instruments to measure service quality in higher education

The purpose of this work is to examine the performance of five alternative measures of service quality in the high education sector – SERVQUAL (Service Quality), Importance-weighted SERVQUAL, SERVPERF (Service Performance), Importance-weighted SERVPERF and HedPERF (Higher Education Performance). We aim at determining which instrument has the superior measurement capability. Data were collected by means of a structured questionnaire containing perception items enhanced from the SERVPERF and HEdPERF scales and expectation items from the SERVQUAL scale, both modified to fit into the higher education sector. The first draft of the questionnaire was subject to a pilot testing through a focus group and an expert evaluation. Data were gathered from a 360 students’ sample of a Portuguese university in Lisbon. Scales were compared in terms of unidimensionality, reliability, validity and explained variance. Managerial conclusions were also drawn.service quality scales; higher education; reliability

Portuguese media discourse on nuclear energy before and after Fukushima: prepared for the EFDA Workprogramme 2012 WP12-SER-ACIF-1

This report presents the results of the analysis of nuclear related content in Portuguese print media. The report is submitted to the first step of the research task untitled Public Discourse about Nuclear Fusion before and after the Fukushima accident, as part of the Socio-Economic Research on Fusion under the general coordination of EFDA Workprogramme 2012

Comparing Airport regulation in Europe: Is there need for a European Regulator?

This paper provides an overview of how the major airports are regulated in Europe. In order to eliminate the potential of airports to exercise market power and protect the public interest, it has become increasingly necessary to set a common regulatory framework. We intend to discuss the need of a single regulator in Europe to monitor or establish the quality of service and the charges practiced by the airports, to ensure cost-relatedness, transparency and non-discrimination. The existing regulatory approaches regarding aeronautical charges and their economic implications are also analyzed. We propose the creation of a European Observatory for this sector.airports, economic regulation, European Observatory

Examining the segment retention problem for the “Group Satellite” case

The purpose of this work is to determine how well, criteria designed to help the selection of the adequate number of market segments, perform in recovering small niche segments, in mixture regressions of normal data, with experimental data. The simulation experiment compares several segment retention criteria, including information criteria and classification-based criteria. We also address the impact of distributional misspecification on segment retention criteria success rates. This study shows that Akaike’s Information criterion with penalty factors of 3 and 4, rather than the traditional value of 2, are the best segment retention criteria to use in recovering small niche segments. Although these criteria were designed for the specific context of mixture models, they are rarely applied in the marketing literature.Information criteria; Latent Class Segmentation.

Assessing the Number of Components in Mixture Models: a Review.

Despite the widespread application of finite mixture models, the decision of how many classes are required to adequately represent the data is, according to many authors, an important, but unsolved issue. This work aims to review, describe and organize the available approaches designed to help the selection of the adequate number of mixture components (including Monte Carlo test procedures, information criteria and classification-based criteria); we also provide some published simulation results about their relative performance, with the purpose of identifying the scenarios where each criterion is more effective (adequate).Finite mixture; number of mixture components; information criteria; simulation studies.