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

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.

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

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.

Topology of Moduli Spaces of Free Group Representations in Real Reductive Groups

Let $G$ be a real reductive algebraic group with maximal compact subgroup $K$, and let $F_r$ be a rank $r$ free group. We show that the space of closed orbits in $\mathrm{Hom}(F_r,G)/G$ admits a strong deformation retraction to the orbit space $\mathrm{Hom}(F_r,K)/K$. In particular, all such spaces have the same homotopy type. We compute the Poincar\'e polynomials of these spaces for some low rank groups $G$, such as $\mathrm{Sp}(4,\mathbb{R})$ and $\mathrm{U}(2,2)$. We also compare these real moduli spaces to the real points of the corresponding complex moduli spaces, and describe the geometry of many examples.Comment: v2: exposition improved, typos corrected, and a minor gap in a proof fixed; 25 pages; accepted at Forum Mathematicu

Comparative Analysis of the public discourse about fusion and nuclear energy before and after Fukushima: WP12-SER-ACIF-1 Final Report

This report presents a comparative analysis of media coverage of fusion and fission energy before and after the accident in the nuclear reactors of Fukushima, Japan. The analysis is based on research conducted under the EFDA Workprogramme 2012, addressing three national-based print media – Germany, Spain and Portugal as well as English-language print media addressing transnational elite

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

Democracy and Economic Development: a Fuzzy Classification Approach

The aim of this work is to (1) analyse whether countries differ on political indicators (democracy, rule of law, government effectiveness and corruption) and (2) study whether countries with different political profiles are associated with different levels of economic, human development and gender-related development indicators. Using a fuzzy classification approach (fuzzy k-means algorithm), we propose a typology of 124 countries based on 10 political variables. Six segments are identified; these political groups implicate the access to different levels of economic and human development. In this study evidence of a positive but not perfect relationship between democracy and economic and human development is observed, thus presenting new insights for the understanding of the heterogeneity of behaviors relatively to political indicators.Democracy, Economic Development, Fuzzy k-means