On the evolution of online tourism communities - Network battle or longtail niches?

Even though the emergence or respectively the construction of online communities is of great interest for scientists and community engineers, only few empirical data has been presented on community growth. This article starts with a reflection on possible growth curves of virtual communities. It contrasts a network externality perspective that produces clear winners and losers in a market with a long tail perspective that also allows small niche products to be successful. These considerations are empirically tested with a sample of 74 travel communities whose numbers of registered members were recorded at two measure points. The results show that online travel communities develop into an archetypical long tail. A very small number of communities with exceedingly high numbers of members are accompanied by a vast amount of communities with only few members. An analysis of the long tail, however, reveals that the community tail is not dead but is populated by a large number of especially regional communities that show considerable growth rates

A Randomized Controlled Trial Comparing two Cognitive-Behavioral Programs for Adolescent Girls with Subclinical Depression: A School-Based Program (Op Volle Kracht) and a Computerized Program (SPARX)

Limited research has indicated the effectiveness of the school-based Cognitive Behavioral Therapy (CBT) prevention program ‘Op Volle Kracht (OVK)’ and the computerized CBT program ‘SPARX’ in decreasing depressive symptoms. Therefore, a randomized controlled trial of the effectiveness of OVK and SPARX was conducted among Dutch female adolescents (n = 208, mean age = 13.35) with elevated depressive symptoms. Participants were randomly assigned to one of four conditions: OVK only (n = 50), SPARX only (n = 51), OVK and SPARX combined (n = 56) and a monitoring control condition (n = 51). Participants in the first three conditions received OVK lessons and/or the SPARX game. Depressive symptoms were assessed before interventions started, weekly during the interventions, and immediately after the interventions ended, with follow-up assessments at 3, 6 and 12 months. Intention to treat results showed that depressive symptoms decreased in all conditions (F(12, 1853.03) = 14.62, p < .001), with no difference in depressive symptoms between conditions. Thus, all conditions, including the monitoring control condition, were equally effective in reducing depressive symptoms. Possible explanations for the decrease of depressive symptoms in all conditions are discussed and suggestions for future research are provided. Dutch Trial Register: NTR3737

A Bayesian Approach to Risk Management in a World of High-Frequency Data

A Realised Volatility GARCH model using high-frequency data is developed within a Bayesian framework for the purpose of forecasting Value at Risk and Conditional Value at Risk. A Skewed Student-t return distribution is combined with a Student-t distribution in the measurement equation in a GARCH framework. Realised Volatility GARCH models show a marked improvement compared to ordinary GARCH. A Skewed Student-t Realised DCC copula model using Realised Volatility GARCH marginal functions is developed within a Bayesian framework for the purpose of forecasting portfolio tail risk. The use of copulas is implemented so that the marginal distributions can be separated from the dependence structure to produce tail forecasts. This is compared to using traditional GARCH-copula models, and GARCH on an aggregated portfolio. Copula models implementing a Realised Volatility GARCH framework show an improvement over traditional GARCH models. A Bayesian detection of regime changes utilizing high-frequency data is developed, once again for the purpose of forecasting portfolio tail risk. The use of high-frequency data improves the accuracy of regime change detection compared to daily data. Monte Carlo sampling schemes are employed for the estimation of these models

Thermography and thermoregulation of the face

BACKGROUND: Although clinical diagnosis of thermoregulation is gaining in importance there is no consistent evidence on the value of thermography of the facial region. In particular there are no reference values established with standardised methods. METHODS: Skin temperatures were measured in the facial area at 32 fixed measuring sites in 26 health subjects (7–72 years) with the aid of a contact thermograph (Eidatherm). A total of 6 measurements were performed separately for the two sides of the face at intervals of equal lengths (4 hours) over a period of 24 hours. Thermoregulation was triggered by application of a cold stimulus in the region of the ipsilateral ear lobe. RESULTS: Comparison of the sides revealed significant asymmetry of face temperature. The left side of the face showed a temperature that was on the average 0.1°C lower than on the right. No increase in temperature was found following application of the cold stimulus. However, a significant circadian rhythm with mean temperature differences of 0.7°C was observed. CONCLUSION: The results obtained should be seen as an initial basis for compiling an exact thermoprofile of the surface temperature of the facial region that takes into account the circadian rhythm, thus closing gaps in studies on physiological changes in the temperature of the skin of the face

Methods to study splicing from high-throughput RNA Sequencing data

The development of novel high-throughput sequencing (HTS) methods for RNA (RNA-Seq) has provided a very powerful mean to study splicing under multiple conditions at unprecedented depth. However, the complexity of the information to be analyzed has turned this into a challenging task. In the last few years, a plethora of tools have been developed, allowing researchers to process RNA-Seq data to study the expression of isoforms and splicing events, and their relative changes under different conditions. We provide an overview of the methods available to study splicing from short RNA-Seq data. We group the methods according to the different questions they address: 1) Assignment of the sequencing reads to their likely gene of origin. This is addressed by methods that map reads to the genome and/or to the available gene annotations. 2) Recovering the sequence of splicing events and isoforms. This is addressed by transcript reconstruction and de novo assembly methods. 3) Quantification of events and isoforms. Either after reconstructing transcripts or using an annotation, many methods estimate the expression level or the relative usage of isoforms and/or events. 4) Providing an isoform or event view of differential splicing or expression. These include methods that compare relative event/isoform abundance or isoform expression across two or more conditions. 5) Visualizing splicing regulation. Various tools facilitate the visualization of the RNA-Seq data in the context of alternative splicing. In this review, we do not describe the specific mathematical models behind each method. Our aim is rather to provide an overview that could serve as an entry point for users who need to decide on a suitable tool for a specific analysis. We also attempt to propose a classification of the tools according to the operations they do, to facilitate the comparison and choice of methods.Comment: 31 pages, 1 figure, 9 tables. Small corrections adde