Discrimination between Demodex folliculorum (Acari: Demodicidae) isolates from China and Spain based on mitochondrial cox1 sequences

For a long time, classification of Demodex mites has been based mainly on their hosts and phenotypic characteristics. A new subspecies of Demodex folliculorum has been proposed, but not confirmed. Here, cox1 partial sequences of nine isolates of three Demodex species from two geographical sources (China and Spain) were studied to conduct molecular identification of D. folliculorum. Sequencing showed that the mitochondrial cox1 fragments of five D. folliculorum isolates from the facial skin of Chinese individuals were 429 bp long and that their sequence identity was 97.4%. The average sequence divergence was 1.24% among the five Chinese isolates, 0.94% between the two geographical isolate groups (China (5) and Spain (1)), and 2.15% between the two facial tissue sources (facial skin (6) and eyelids (1)). The genetic distance and rate of third-position nucleotide transition/transversion were 0.0125, 2.7 (3/1) among the five Chinese isolates, 0.0094, 3.1 (3/1) between the two geographical isolate groups, and 0.0217, 4.4 (3/1) between the two facial tissue sources. Phylogenetic trees showed that D. folliculorum from the two geographical isolate groups did not form sister clades, while those from different facial tissue sources did. According to the molecular characteristics, it appears that subspecies differentiation might not have occurred and that D. folliculorum isolates from the two geographical sources are of the same population. However, population differentiation might be occurring between isolates from facial skin and eyelids.     

Innovation and network multiplexity: R&D and the concurrent effects of two collaboration networks in an emerging economy

This study focuses on the multiplexity of firm R&D networks, and it investigates two types of boundary-spanning networks: the bipartite network between firms and government-sponsored institutions (GSIs), and the traditional firm–firm network. We apply a social network perspective to examine the effects that these kinds of networks have on firm innovativeness, in relation to the effects of the firm’s internal R&D efforts. We define the firm-GSI network as bipartite, and we investigate how the structural characteristics of this network (cohesion and centrality) affect innovativeness. We then decompose the innovational effects of firm–firm networks into two categories (intra- and inter-sector) to distinguish the effects of these collaboration networks. Furthermore, we investigate how these various external collaborative networks interact with a firm’s internal R&D efforts for driving innovativeness. Our empirical study of 420 manufacturing firms in Mexico evaluates evidence from surveys and secondary data. The findings indicate that the structural properties of both firm–GSI and firm–firm networks have positive effects on innovativeness, but firm–GSI network cohesion has a stronger negative interaction with R&D in influencing firm innovativeness. Moreover, intra-sector centrality in a firm–firm network has a stronger negative interaction with R&D than inter-sector centrality does in driving firm innovativeness. We contribute to the literature by integrating insights from the perspectives of network multiplexity, social embeddedness, and resource complementarity in regard to inter-organizational behavior. Our study also provides meaningful guidelines for both managers and policy makers. The study’s findings are robust to concerns of common method bias and alternative model specifications.     

Training to Use the Scientific Method in a First-Year Physics Laboratory: A Case Study

Journal of Science Education and Technology - In this work, a specific implementation of a so-called experimental or open-ended laboratory is proposed and evaluated. Keeping in mind the scheduling...     

Perceptions of the Media and the Public and their Effects on Political Participation in Colombia

This study investigates whether perceptions of the media and the public are related to political participation in Colombia. Communication researchers have built a large body of literature on hostile media perceptions and the projection effect, respectively. This study links these perceptual effects with each other and with political participation. Analyzing survey data from a representative sample of Colombian adults in urban areas, we show a direct relationship between hostile media perceptions and participation but no direct relationship between projection and participation. Hostile media perceptions and projection are negatively related. Results suggest that perceived media bias attenuates projection but increases political engagement.