The Evolving Nature of the Computer Self-Efficacy Construct: An Empirical Investigation of Measurement Construction, Validity, Reliability and Stability Over Time.

This paper reports an empirical study intended to provide detailed comparisons amongst and between the varieties of available measures of computer self-efficacy (CSE). Our purpose is to ascertain their relative abilities to isolate the CSE construct from other related constructs and to capture variance in performance attributed to changes in CSE level. In addition, we investigate the importance of ensuring the measure being used is sufficiently aligned with the task domain of interest. Finally, we explore the stability of CSE measures as they relate to the current state of evolution within the computing domain. Marakas, Yi, and Johnson (1998) proposed a framework for the construction of instruments intended to measure the CSE construct that we have adopted as a basis for this series of investigations. To that end, we advance and test a set of hypotheses derived from the Marakas et al. (1998) framework. Results of the analyses support the need for adherence to the tenets of the proposed framework as well as provide evidence that CSE measures suffer from degradation of their explanatory power over time. Further, this study brings forth the importance of appropriately validating measures of CSE using approaches intended for a formative rather than a reflective construct. These results suggest that the common practices of instrument validation and reuse of long-standing instruments to measure CSE may not be the most effective approach to the study of the construct. Implications for future research are discussed

Deconstructing and Operationalizing Interactivity: An Online Advertising Perspective

In an online advertising context this empirical study examines the influence of the interface characteristic Interactivity on important user perceptions and their intention to use a website. Results indicate that social presence and telepresence are significant predictors of attitude toward online advertisements, satisfaction with online advertisements, and subsequent intentions to use a host website. Also indicated by this study is the significant influence of interactivity, as well as consumer involvement and the interaction between these two variables. The outcomes of this study offer preliminary insight into the conceptualization and affect of interface characteristics, such as interactivity, in online advertising

From Individual Cognition to Social Ecosystem: A Structuration Model of Enterprise Systems Use

In this paper, we argue that one can understand the adoption and routine use of enterprise systems by examining the fit between the system and the social structures of the organization. We develop a model of the adoption and long- term use of enterprise systems based on sociological concepts (Lord Anthony Giddens’ structuration theory) rather than the usual cognitive psychology concepts. We focus on the adoption and use of three versions of an enterprise KMS to support sales representatives at a multinational pharmaceutical firm. Our first study (a five-year case study of the KMS that went through one failed deployment and two successful ones) shows that the structures of signification, legitimation, and domination all influence loyal use, although domination may be less important. Our second study (a survey of 893 users at the firm) shows that the structures of signification, legitimation, and domination explain about 50 percent of the variance in ongoing loyal use but that their relative importance depends on the job experience of the users: signification and legitimation influence novices more, and signification and domination influence experts more. We believe that this parsimonious three-factor model offers a useful approach for future research and practice

As redes sociais na internet e suas apropriações por jovens brasileiros e portugueses em idade escolar

O fenômeno das redes sociais on-line é marcante na atual fase da internet 2.0, tendo crescido vertiginosamente, a partir do ano 2005, com a adesão majoritária de jovens, que as acessam por computadores fixos e móveis, em plataformas dos mais variados tipos. Por meio delas, trocam mensagens e compartilham conteúdos os mais diversos. Diante desse cenário, com base em duas pesquisas convergentes, pretende-se discutir os usos e as apropriações das redes sociais on-line por jovens alunos do ensino fundamental e médio e destacar os pontos mais pertinentes da atual fase da internet nos contextos pessoal, familiar e escolar. Foram aplicados questionários, inspirados em modelo de pesquisa elaborado na Itália, a 404 alunos brasileiros de oito escolas no Rio de Janeiro e a 549 alunos portugueses de 11 escolas na região portuguesa de Castelo Branco. Com essa rica empiria, verificou-se em que pontos os jovens se aproximam dos ideais de uma nova subjetividade (o leitor imerso nas novas mídias) e de um jovem naturalmente afeito aos suportes digitais (o nativo digital).The phenomenon of online social networks has been remarkable in the current phase of internet 2.0 and has grown rapidly from the year 2005, with the majority membership of young people, who access the social networks from desktops and mobile platforms of all kinds. Using these platforms, they exchange messages and share various contents. Given this scenario, based on two converging researches, this paper discusses the uses and appropriations of online social networks by students of elementary school and high school. Also, it highlights the most relevant points in the current phase of the internet in relation to personal, family and school contexts. Inspired by a research model developed in Italy, 404 questionnaires were applied to Brazilian students from eight schools in Rio de Janeiro and 549 Portuguese students from 11 schools in the Portuguese region of Castelo Branco. With this comprehensive database, we could verify at which points the youth approaches the ideals of a new subjectivity (the reader immersed in new medias) and a youngster naturally used to digital media (the digital native).info:eu-repo/semantics/publishedVersio

ClustScan: an integrated program package for the semi-automatic annotation of modular biosynthetic gene clusters and in silico prediction of novel chemical structures

The program package ‘ClustScan’ (Cluster Scanner) is designed for rapid, semi-automatic, annotation of DNA sequences encoding modular biosynthetic enzymes including polyketide synthases (PKS), non-ribosomal peptide synthetases (NRPS) and hybrid (PKS/NRPS) enzymes. The program displays the predicted chemical structures of products as well as allowing export of the structures in a standard format for analyses with other programs. Recent advances in understanding of enzyme function are incorporated to make knowledge-based predictions about the stereochemistry of products. The program structure allows easy incorporation of additional knowledge about domain specificities and function. The results of analyses are presented to the user in a graphical interface, which also allows easy editing of the predictions to incorporate user experience. The versatility of this program package has been demonstrated by annotating biochemical pathways in microbial, invertebrate animal and metagenomic datasets. The speed and convenience of the package allows the annotation of all PKS and NRPS clusters in a complete Actinobacteria genome in 2–3 man hours. The open architecture of ClustScan allows easy integration with other programs, facilitating further analyses of results, which is useful for a broad range of researchers in the chemical and biological sciences

Relative Bioavailability and Bioaccessibility and Speciation of Arsenic in Contaminated Soils

Background: Assessment of soil arsenic (As) bioavailability may profoundly affect the extent of remediation required at contaminated sites by improving human exposure estimates. Because small adjustments in soil As bioavailability estimates can significantly alter risk assessments and remediation goals, convenient, rapid, reliable, and inexpensive tools are needed to determine soil As bioavailability

Ultrahigh Energy Cosmic Rays: The state of the art before the Auger Observatory

In this review we discuss the important progress made in recent years towards understanding the experimental data on cosmic rays with energies \agt 10^{19} eV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition, and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the conjectured nearby cosmic ray sources. We then turn to theoretical notions of physics beyond the Standard Model where we consider both exotic primaries and exotic physical laws. Particular attention is given to the role that TeV-scale gravity could play in addressing the origin of the highest energy cosmic rays. In the final part of the review we discuss the potential of future cosmic ray experiments for the discovery of tiny black holes that should be produced in the Earth's atmosphere if TeV-scale gravity is realized in Nature.Comment: Final version. To be published in Int. J. Mod. Phys.

Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter

An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft (RPA) carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is unchanged with respect to v2. 39 pages, 15 figures, 2 table