What determines the mobility of charge carriers in conjugated polymers?

In a conjugated polymer, the mobility of charge carriers is not a well-defined coefficient of a particular material as it is in an inorganic crystalline semiconductor but depends on the time domain of detection. On a time-scale of typically 100 fs, the on-chain mobility is ultra-high and controlled by the electronic band width of the polymer chain. When a carrier hits a chain imperfection, subsequent mesoscopic on-chain motion is retarded and controlled by intrachain disorder to which the chain environment contributes. Macroscopic transport commences after a time when interchain carrier jumps become rate limiting. It is routinely probed by time-of-flight experiments and can be rationalized in terms of random walk within a rough energy landscape. Experimental signatures of the various modes of transport are discussed.     

The “meaning” of citation in the context of a scientifically peripheral country

This paper reports an investigation into the referencing pattern of Brazilian agricultural scientists. The study was based on the use of both quantitative data-citations appearing in a sizeable sample of articles published by these scientists—and qualitative data-interviews with a large number of scientists who authored the source, papers. The aim was to explore the extent to which citation counts may be taken as valid indicators of the quality, influence or impact of published scientific knowledge in the general context of a scientifically peripheral country. The findings presented confirm the view that in this context, citation patterns are significantly influenced by factors external to the scientific realm and, thus, reflect neither simply the quality, influence nor even the impact of the research work referred to.     

Different manifestations of ‘context’: examples from a bibliometric study of research in Zimbabwe in Southern Africa

Scientometrics - ‘Context’ refers to the environment in which a phenomenon exists or takes place, and which can help to understand the phenomenon. Aspects of context are present in all...     

‘Cognitive mobility’ or migration of authors between fields used in mapping a network of mathematics

In this paper we have looked at a new measure of connectedness between research areas, namely, the migration of authors between subfields as seen from their contributions to different areas. Migration may be considered as an embodied knowledge flow that bridges some part of the cognitive gap between fields. Our hypothesis is that the rate of author migration will reflect cognitive similarity or affinity between disciplines. This is graphically shown to be reasonable, but only above certain levels of migration for our data from mathematical reviews spanning 17 years (1959–1975). The inter-related structure of Mathematics is then mapped using migration data in the appropriate range. We find the resulting map to be a good reflection of the disciplinary variation in the field of Mathematics.     

Experience in polyharmonic analysis of the parameters of the earth’s rotation

A method for approximating time series by an nth degree trigonometric polynomial for a series of parameters of the Earths rotation, calculated from GPS and GLONASS measurements, is tested. Satisfactory agreement is obtained between the model and experimental data. The results can be used for complex modeling and forecasting of the parameters of the Earths rotation.Translated from Izmeritelnaya Tekhnika, No. 12, pp. 40–42, December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Influence of the international collaboration in the field of metric studies of science and technology: the case of Mexico (1971–2018)

Scientometrics - We perform a bibliometric analysis of the research production and impact of Mexican scholars involved in the area of metric studies of science and technology in the period...     

A profile of Mexico’s technological agglomerations: The case of the aerospace and nanotechnology industry in Querétaro and Monterrey

This article analyzes the dynamics of emergence of technological clusters in Mexico. In recent years, Mexico has had several initiatives towards the agglomeration of technological capabilities, however, very few cases are successful. The question we are interested in is about how does the technological crowds get configurated. Two Mexican case studies were analyzed in order to identify key endogenous and exogenous factors in the installation and development of technology clusters in the aerospace and nanotechnology. The review of the process of installing both clusters shows the importance of industrial and economic trajectories, the local policy, and the mobilization of local and global actors in the configuration of technological agglomerations. Geographical distances between the technological platforms is important as well, but it requires global players to make the articulation between the local capacities with global trends in emerging technologies.     

Core-periphery,new clusters,or rising stars?: international scientific collaboration among ‘advanced’ countries in the era of globalization

Assuming the OECD member states as ‘advanced’ nations equipped with basic scientific capacities, the present research addresses the network configuration of these countries in international scientific collaboration and the transformation of this network along with globalization. The result suggests that geographical, linguistic, and economic affinities did not have a meaningful impact on the formation of co-authorship network between ‘advanced’ nations, different from previous research results which claimed their importance on international cooperation. Globalization facilitated by the development of information and transportation technologies was found to influence the co-authorship link between countries, but not to accelerate centralization of the network in the past 15 years. Though the core-periphery pattern still persists, new rising stars, which are Korea and Turkey, have emerged in the co-authorship network among ‘advanced’ nations. These two countries, having a rapid increase in the share of degree centrality from 1995 to 2010, had strategic financial support from the government which stimulated the collaboration between universities and industries and emphasized the development of science and engineering fields.     

A survey of ²²²Rn in drinking water in Mexico City

In Mexico City there are more than 22 millions of inhabitants (10 in the metropolitan area and 12 in the suburban zone) exposed to drinking water. The local epidemiological authorities recognised that exposure to radon contaminated drinking water is a potential health hazard, as has been considered worldwide. The United States Environmental Protection Agency has proposed a limit of 11.1 Bq l(-1) for the radon level in drinking water. In Mexico a maximum contamination level of radon in drinking water has not yet even considered. In this work, a (222)Rn study of drinking water in Mexico City has revealed a range of concentrations from background level to 3.8 Bq l(-1). (222)Rn was calculated using a portable degassing system (AquaKIT) associated with an AlphaGUARD measuring system. Samples from 70 wells of the water system of the south of the Valley Basin of Mexico City and from houses of some other political administrative divisions of Mexico City were taken.     

Has globalization strengthened South Korea’s national research system? National and international dynamics of the Triple Helix of scientific co-authorship relationships in South Korea

We trace the structural patterns of co-authorship between Korean researchers at three institutional types (university, government, and industry) and their international partners in terms of the mutual information generated in these relations. Data were collected from the Web of Science during the period 1968–2009. The traditional Triple-Helix indicator was modified to measure the evolving network of co-authorship relations. The results show that international co-authorship relations have varied considerably over time and with changes in government policies, but most relations have become stable since the early 2000s. In other words, the national publication system of Korea has gained some synergy from R&D internationalization during the 1990s, but the development seems to stagnate particularly at the national level: whereas both university and industrial collaborations are internationalized, the cross-connection within Korea has steadily eroded.     

Simulation of the motion and destruction of bolides in the Earth’s atmosphere

Issues of high-temperature interaction of bolides with the Earth’s atmosphere are considered. As an example, the motion and destruction of the Chelyabinsk (Chebarkul) meteorite are studied. The calculation results are compared with data of observations.     

Emergence of modern scientific discourse in the American continent: knowledge claims in the discovery of Erythronium/Vanadium in Mexico (1802–1832)

In the present paper, we study the discovery of the chemical element number 23, Erythronium/Vanadium (E/V), as an early example of the modern process of validating knowledge claims in México. We examined the published work between 1802 and 1832 of Andrés Manuel del Río (AMR) in the Royal Mining Seminar of México and contrasted the styles of argument and forms of certification between his teaching and experimental writings concerning his claim to the paternity of E/V discovery. We also analyze the respective papers of European authors that replicated, rediscovered and certified AMR’s finding. We use a combination of bibliometric, sociotechnical network and literary critical analysis in order to show that the certification of E/V spawned an emerging mode for producing and validating new knowledge in the American continent and particularly in México. In turn, this approach supports AMR’s claim to the discovery of E/V from the production process of the lead brown ore in Zimapán, México.

     

What can information-asymmetric games tell us about the context of Crick's ‘frozen accident’?

This paper describes a novel application of information-asymmetric (signalling) games to molecular biology in which utility is determined by the message complexity (rate) in addition to the error in information transfer (distortion). We show using a computational model how it is possible for the agents in one such game to evolve a signalling convention (separating equilibrium) that is suboptimal in terms of information transfer, but is nonetheless stable. In the context of an RNA world merging with a nascent amino acid one, such a game''s equilibrium is alluded to by the genetic code, which is nearly optimal in terms of information transfer, but is also near-universal and nearly immutable. Such a framework suggests that cellularity may have emerged to encourage coordination between RNA species and sheds light on other aspects of RNA world biochemistry yet to be fully understood.     

Measuring changes in publication patterns in a context of performance-based research funding systems: the case of educational research in the University of Gothenburg (2005–2014)

Scientometrics - We present a novel way to frame a discussion of changes in publication patterns that occur in a context of performance-based research funding systems (PRFSs). Adopting an approach...     

Carbonation in concrete infrastructure in the context of global climate change: Part 2 – Canadian urban simulations

In Part 1 of this paper, a carbonation model was developed and experimentally verified which was able to forecast carbonation depth of a concrete specimen considering varying ambient temperature, humidity and CO₂ concentrations.Part 2 of the paper applies the carbonation diffusion/reaction model developed in Part 1 to predict the effects of global climate change on the carbonation of concrete. Climate scenarios were formulated and combined with the model for two major Canadian cities, Toronto and Vancouver. Results show that for undamaged and unstressed concrete, climate change will significantly affect carbonation progress. The model showed that for unloaded, non-pozzolanic concrete, ultimate carbonation depths in Toronto and Vancouver could be up to 45% higher. For in-service structures under load, the rates of deterioration are likely to be even faster. This is a cause for concern, and much further effort must be devoted to fully understand these phenomena.     

Are leaders really leading? Journals that are first in Web of Science subject categories in the context of their groups

This study focuses on journals that lead their Web of Science (WoS) subject category ranking when the usual 2-year window for the Journal Impact Factor (JIF2) is used as the ranking variable, and examines evidence that contradicts their top-ranked position in the context of their group. The source data were obtained from all 177 WoS subject categories in the Science Edition 2015 Journal Citation Reports (JCR). I compared journals in each WoS subject category with leaders in terms of JIF2, number of citable items and number of citations that contribute to the JIF2. Rankings were calculated with alternative metrics (for example, the Journal Impact Factor without self-citations and the eigenfactor), and the minimum reduction in the number of citations that would displace the top-ranked journal from its leading position was also calculated. In addition, the stability of rankings over time, the number of WoS subject categories in which journals are leaders, the publishers that own leading journals, and the percentages of research articles (as opposed to review articles) published in different journals were also studied. In general, leading journals are not necessarily the top-ranked in terms of citations received or the number of citable items they publish. In addition, most leaders maintained their position when other metrics were used instead the JIF2, although rankings based on the eigenfactor were at variance with this finding. The distribution of publishers was highly skewed, with a linear relationship between the cumulative number of publishers owning the top-ranked journal and the cumulative number of WoS subject categories. In only 85 subject categories (48%) the percentage of research articles (not reviews) in the number of citable items was greater than the mean percentage for the subject category. In 31 instances, leaders did not publish any research articles, but only reviews.     

Direct observation of the ‘hydrodynamic’ flow of the intermediate-state structure in pure indium

The influence of a static perturbation of the magnetic field on the current-induced motion of the normal and superconducting domains in a pure, uncompensated, type I superconductor (indium) in the intermediate state has been observed using a high-resolution magnetooptical technique. We report here these observations, which bring the first direct evidence of the nonlinear hydrodynamic flow properties of the intermediate state predicted by Andreev and which are closely related to the additional resistance recently observed by Krylov in the intermediate state of pure indium.Work performed with the financial support of the Fonds National Suisse pour la Recherche Scientifique.Visiting Scientist under the auspices of the Swiss-Russian Scientific Exchange Program.     

Exploring the determinants of users’ continuance intention in smartwatches

The purpose of this study is to examine possible factors that influence continuance intention to use a smartwatch. The proposed research model is based on the expectation confirmation model adapted to include individual mobility, perceived aesthetics, and habit. The sample consisted of 348 actual users of smartwatches and structural equation modeling (SEM) was employed to test the research model. The results indicate that perceived aesthetics, satisfaction, individual mobility, and habit are associated with individuals’ continuance intention to use smartwatches. Surprisingly, perceived usefulness does not directly influence continuance intention of smartwatches. The implications for both theory and practice are provided based on the findings.     

Atomic-scale mechanism of the θ’’→θ’ phase transformation in Al-Cu alloys

The phase transformation of θ’’→θ’ in an Al-5.7 Cu alloy was investigated by aberration-corrected scanning transmission electron microscopy, and the tranformation mode of θ’’→θ’ during aging treatment was clarified. In the presence of the θ’ phases, θ’ was found to be formed by in-situ transformation fromθ’’ with the same plate shape, size and broad faces. The transformation starts from multiple sites within the θ’ precipitate and the whole θ’ phase finally forms as the preferential θ’ sections grow and connect with each other. Antiphase domain boundaries are also found in some θ’ precipitates when the disregistry exists between different θ’ sections.