A simple index for the high-citation tail of citation distribution to quantify research performance in countries and institutions

Educational technologies and elementary level education - A bibliometric review of scopus indexed journal articles

This bibliometric study critically analyses 293 journal articles from the Scopus database, charting the trajectory of educational technology in primary and elementary education from 1986 to 2023. While limited to practical applications within primary or elementary contexts and excluding various scholarly work forms, the research unveils crucial insights. A significant uptick in publications during 2008-2016 and 2018-2023 highlights the growing importance and incorporation of digital technologies in early education. The analysis identifies recurrent themes like teacher education, game-based learning, and collaborative learning, pointing towards future research directions. The study also notes underexplored areas, including technology's role in specific subjects, ethical student engagement, gender and disability dynamics, and contributions from African contexts. It advocates for increased international collaboration, with a focus on partnerships with predominant Chinese institutions. Despite its limitations, this paper is foundational for future research, offering a roadmap for a nuanced understanding of technology's impact on young learners' educational experiences and outcomes globally.

Advanced Extraction of Lipids with DHA from Isochrysis galbana with Enzymatic Pre-Treatment Combined with Pressurized Liquids and Ultrasound Assisted Extractions

Microalgal biomass is a sustainable and valuable source of lipids with omega-3 fatty acids. The efficient extraction of lipids from microalgae requires fast and alternative extraction methods, frequently combined with biomass pre-treatment by different procedures. In this work, Pressurized liquid extraction (PLE) was optimized and compared with traditional lipid extraction methods, Folch and Bligh and Dyer, and with a new Ultrasound Assisted Extraction (UAE) method for lipids from microalgae Isochrysis galbana. To further optimize PLE and UAE, enzymatic pre-treatment of microalga Isochrysis galbana was studied with commercial enzymes Viscozyme and Celluclast. No significant differences were found for lipid yields among different extraction techniques used. However, advanced extraction techniques with or without pre-treatment are a green, fast, and toxic solvent free alternative to traditional techniques. Lipid composition of Isochrysis was determined by HPLC-ELSD and included neutral and polar lipids, showing that each fraction comprised different contents in omega-3 polyunsaturated fatty acids (PUFA). The highest polar lipids content was achieved with UAE (50 °C and 15 min) and PLE (100 °C) techniques. Moreover, the highest omega-3 PUFA (33.2%), eicosapentaenoic acid (EPA) (3.3%) and docosahexaenoic acid (DHA) (12.0%) contents were achieved with the advanced technique UAE, showing the optimized method as a practical alternative to produce valuable lipids for food and nutraceutical applications.

A Diet With Docosahexaenoic and Arachidonic Acids as the Sole Source of Polyunsaturated Fatty Acids Is Sufficient to Support Visual, Cognitive, Motor, and Social Development in Mice

Polyunsaturated fatty acids serve multiple functions in neurodevelopment and neurocognitive function. Intravenous lipid emulsions are administered to children that are dependent on parenteral nutrition to provide the essential fatty acids needed to sustain growth and development. One of these emulsions, derived from fish-oil, is particularly poor in the traditional essential fatty acids, linoleic and alpha-linolenic acids. However, it does contain adequate amounts of its main derivatives, arachidonic acid (ARA) and docosahexaenoic acid (DHA), respectively. This skewed composition has raised concern about the sole use of fish-oil based lipid emulsions in children and how its administration can be detrimental to their neurodevelopment. Using a custom-made diet that contains ARA and DHA as a sole source of polyunsaturated fatty acids, we bred and fed mice for multiple generations. Compared to adult, chow-fed mice, animals maintained on this special diet showed similar outcomes in a battery of neurocognitive tests performed under controlled conditions. Chow-fed mice did perform better in the rotarod test for ataxia and balance, although both experimental groups showed a conserved motor learning capacity. Conversely, mice fed the custom diet rich in DHA and ARA showed less neophobia than the chow-fed animals. Results from these experiments suggest that providing a diet where ARA and DHA are the sole source of polyunsaturated fatty acids is sufficient to support gross visual, cognitive, motor, and social development in mice.

Plasmalogen lipids: functional mechanism and their involvement in gastrointestinal cancer

The plasmalogens are a class of glycerophospholipids which contain a vinyl-ether and an ester bond at the sn-1 and sn-2 positions, respectively, in the glycerol backbone. They constitute 10 mol% of the total mass of phospholipids in humans, mainly as membrane structure components. Plasmalogens are important for the organization and stability of lipid raft microdomains and cholesterol-rich membrane regions involved in cellular signaling. In addition to their structural roles, a subset of ether lipids are thought to function as endogenous antioxidants and emerging studies suggest that they are involved in cell differentiation and signaling pathways. Although the clinical significance of plasmalogens is linked to peroxisomal disorders, the pathophysiological roles and their possible metabolic pathways are not fully understood since they present unique structural attributes for the different tissue types. Studies suggest that changes in plasmalogen metabolism may contribute to the development of various types of cancer. Here, we review the molecular characteristics of plasmalogens in order to significantly increase our understanding of the plasmalogen molecule and its involvement in gastrointestinal cancers as well as other types of cancers.

Evolution of three Nobel Prize themes and a Nobel snub theme in chemistry: a bibliometric study with focus on international collaboration

In this study, three chemistry research themes closely associated with the Nobel Prize are bibliometrically analyzed—Ribozyme, Ozone and Fullerene—as well as a research theme in chemistry not associated with the Nobel Prize (a Nobel snub theme): Brunauer–Emmett–Teller equation. We analyze, based on an algorithmically constructed publication-level classification system, the evolution of the four themes with respect to publication volume and international collaboration, using two datasets, one of them a subset of highly cited publications, for each considered time period. The focus of the study is on international collaboration, where co-occurrence of country names in publications is used as a proxy for international collaboration. For all four themes, especially for Brunauer–Emmett–Teller equation, the publication volumes increase considerably from the earliest period to the later periods. The international collaboration rate shows an increasing trend for each theme. For Ozone, Fullerene and Brunauer–Emmett–Teller equation, the international collaboration rate tend to be higher for the highly cited publications compared to full datasets. With regard to the evolution of number of countries per international publication and per highly cited international publication, a vast majority of the distributions are positively skewed, with a large share of publications with two countries. With respect to the last four periods of the study, the concentration to two countries per publication is more pronounced for the Brunauer–Emmett–Teller equation theme compared to the three Nobel Prize themes.

Model-based evaluation of scientific impact indicators

Using bibliometric data artificially generated through a model of citation dynamics calibrated on empirical data, we compare several indicators for the scientific impact of individual researchers. The use of such a controlled setup has the advantage of avoiding the biases present in real databases, and it allows us to assess which aspects of the model dynamics and which traits of individual researchers a particular indicator actually reflects. We find that the simple average citation count of the authored papers performs well in capturing the intrinsic scientific ability of researchers, regardless of the length of their career. On the other hand, when productivity complements ability in the evaluation process, the notorious h and g indices reveal their potential, yet their normalized variants do not always yield a fair comparison between researchers at different career stages. Notably, the use of logarithmic units for citation counts allows us to build simple indicators with performance equal to that of h and g. Our analysis may provide useful hints for a proper use of bibliometric indicators. Additionally, our framework can be extended by including other aspects of the scientific production process and citation dynamics, with the potential to become a standard tool for the assessment of impact metrics.

At what institutions did Nobel laureates do their prize-winning work? An analysis of biographical information on Nobel laureates from 1994 to 2014

In this study we examined the institutions (and countries) the Nobel laureates of the three disciplines chemistry, physics and physiology/medicine were affiliated with (from 1994 to 2014) when they did the decisive research work. To be able to frame the results at that time point, we also looked at when the Nobel laureates obtained their Ph.D./M.D. and when they were awarded the Nobel Prize. We examined all 155 Nobel laureates of the last 21 years in physics, chemistry, and physiology/medicine. Results showed that the USA dominated as a country. Statistical analysis also revealed that only three institutions can boast a larger number of Nobelists at all three time points examined: UC Berkeley, Columbia University and the Massachusetts Institute of Technology (MIT). Researcher mobility analysis made clear that most of the Nobel laureates were mobile; either after having obtained their Ph.D./M.D. or after writing significant papers that were decisive for the Nobel Prize. Therefore, we distinguished different ways of mobility between countries and between institutions. In most cases, the researchers changed institutes/universities within one and the same country (in first position: the USA, followed, by far, by the United Kingdom, Japan and Germany).

[Bibliometric analysis of publications in Gastroenterology and Hepatology in Spain from 2000 to 2009]

INTRODUCTION

The aim of this study was to analyze the productivity and visibility of Spanish authors in gastroenterology and hepatology between 2000 and 2009 and to compare the results with those for other countries.

METHODS

The Web of Science database was used. The analysis (annual and 5-yearly) was restricted to citable documents. The bibliometric indicators used were the number of documents published, the total number of citations received, the median and interquartile range of the citations received and the Hirsch h index.

RESULTS

We identified 82,740 documents, with an increase of 18.2% between 5-year periods. Seventeen countries published more than 1,000 documents in the decade and received more than 20,000 citations. A total of 14.5% of the documents were international collaborations (20.6% of all citations) and 37.3% were published in journals in the first quartile (66.3% of all citations). The median number of citations received by all the publications was 9 (interquartile range: 3-21) and their h index was 246. Spain ranked ninth for the number of documents and eighth for citations received and for the h index. The countries showing the greatest increase in the percentage of citations contributing to the world total were Canada and Spain, with an increase between 5-yearly periods of 1.16% and 0.95%, respectively.

CONCLUSIONS

From 2000 to 2009, the production of Spanish authors in gastroenterology and hepatology was high, achieving a notable position in the total number of citations received.

Characterizing and modeling citation dynamics

Citation distributions are crucial for the analysis and modeling of the activity of scientists. We investigated bibliometric data of papers published in journals of the American Physical Society, searching for the type of function which best describes the observed citation distributions. We used the goodness of fit with Kolmogorov-Smirnov statistics for three classes of functions: log-normal, simple power law and shifted power law. The shifted power law turns out to be the most reliable hypothesis for all citation networks we derived, which correspond to different time spans. We find that citation dynamics is characterized by bursts, usually occurring within a few years since publication of a paper, and the burst size spans several orders of magnitude. We also investigated the microscopic mechanisms for the evolution of citation networks, by proposing a linear preferential attachment with time dependent initial attractiveness. The model successfully reproduces the empirical citation distributions and accounts for the presence of citation bursts as well.