Knowledge Evolution in Physics Research: An Analysis of Bibliographic Coupling Networks

Even as we advance the frontiers of physics knowledge, our understanding of how this knowledge evolves remains at the descriptive levels of Popper and Kuhn. Using the APS publications data sets, we ask in this letter how new knowledge is built upon old knowledge. We do so by constructing year-to-year bibliographic coupling networks, and identify in them validated communities that represent different research fields. We then visualize their evolutionary relationships in the form of alluvial diagrams, and show how they remain intact through APS journal splits. Quantitatively, we see that most fields undergo weak Popperian mixing, and it is rare for a field to remain isolated/undergo strong mixing. The sizes of fields obey a simple linear growth with recombination. We can also reliably predict the merging between two fields, but not for the considerably more complex splitting. Finally, we report a case study of two fields that underwent repeated merging and splitting around 1995, and how these Kuhnian events are correlated with breakthroughs on BEC, quantum teleportation, and slow light. This impact showed up quantitatively in the citations of the BEC field as a larger proportion of references from during and shortly after these events.Comment: 14 pages, 14 figures, 1 tabl

Concentrations and potential health risks of metals in lip products.

BackgroundMetal content in lip products has been an issue of concern.ObjectivesWe measured lead and eight other metals in a convenience sample of 32 lip products used by young Asian women in Oakland, California, and assessed potential health risks related to estimated intakes of these metals.MethodsWe analyzed lip products by inductively coupled plasma optical emission spectrometry and used previous estimates of lip product usage rates to determine daily oral intakes. We derived acceptable daily intakes (ADIs) based on information used to determine public health goals for exposure, and compared ADIs with estimated intakes to assess potential risks.ResultsMost of the tested lip products contained high concentrations of titanium and aluminum. All examined products had detectable manganese. Lead was detected in 24 products (75%), with an average concentration of 0.36 ± 0.39 ppm, including one sample with 1.32 ppm. When used at the estimated average daily rate, estimated intakes were > 20% of ADIs derived for aluminum, cadmium, chromium, and manganese. In addition, average daily use of 10 products tested would result in chromium intake exceeding our estimated ADI for chromium. For high rates of product use (above the 95th percentile), the percentages of samples with estimated metal intakes exceeding ADIs were 3% for aluminum, 68% for chromium, and 22% for manganese. Estimated intakes of lead were < 20% of ADIs for average and high use.ConclusionsCosmetics safety should be assessed not only by the presence of hazardous contents, but also by comparing estimated exposures with health-based standards. In addition to lead, metals such as aluminum, cadmium, chromium, and manganese require further investigation

Using Machine Learning to Predict the Evolution of Physics Research

The advancement of science as outlined by Popper and Kuhn is largely qualitative, but with bibliometric data it is possible and desirable to develop a quantitative picture of scientific progress. Furthermore it is also important to allocate finite resources to research topics that have growth potential, to accelerate the process from scientific breakthroughs to technological innovations. In this paper, we address this problem of quantitative knowledge evolution by analysing the APS publication data set from 1981 to 2010. We build the bibliographic coupling and co-citation networks, use the Louvain method to detect topical clusters (TCs) in each year, measure the similarity of TCs in consecutive years, and visualize the results as alluvial diagrams. Having the predictive features describing a given TC and its known evolution in the next year, we can train a machine learning model to predict future changes of TCs, i.e., their continuing, dissolving, merging and splitting. We found the number of papers from certain journals, the degree, closeness, and betweenness to be the most predictive features. Additionally, betweenness increases significantly for merging events, and decreases significantly for splitting events. Our results represent a first step from a descriptive understanding of the Science of Science (SciSci), towards one that is ultimately prescriptive.Comment: 24 pages, 10 figures, 4 tables, supplementary information is include

Methodological Issues in Spatial Microsimulation Modelling for Small Area Estimation

In this paper, some vital methodological issues of spatial microsimulation modelling for small area estimation have been addressed, with a particular emphasis given to the reweighting techniques. Most of the review articles in small area estimation have highlighted methodologies based on various statistical models and theories. However, spatial microsimulation modelling is emerging as a very useful alternative means of small area estimation. Our findings demonstrate that spatial microsimulation models are robust and have advantages over other type of models used for small area estimation. The technique uses different methodologies typically based on geographic models and various economic theories. In contrast to statistical model-based approaches, the spatial microsimulation model-based approaches can operate through reweighting techniques such as GREGWT and combinatorial optimization. A comparison between reweighting techniques reveals that they are using quite different iterative algorithms and that their properties also vary. The study also points out a new method for spatial microsimulation modellingBayesian prediction approach; combinatorial optimisation; GREGWT; microdata; small area estimation; spatial microsimulation

The effectiveness of asking behaviors among 9-11 year-old children in increasing home availability and children's intake of fruit and vegetables : results from the Squire's Quest II self-regulation game intervention

Background: Home environment has an important influence on children's fruit and vegetable (FV) consumption, but children may in turn also impact their home FV environment, e.g. by asking for FV. The Squire's Quest II serious game intervention aimed to increase asking behaviors to improve home FV availability and children's FV intake. This study's aims were to assess: 1) did asking behaviors at baseline predict home FV availability at baseline (T0) (RQ1); 2) were asking behaviors and home FV availability influenced by the intervention (RQ2); 3) did increases in asking behaviors predict increased home FV availability (RQ3); and 4) did increases in asking behaviors and increases in home FV availability mediate increases in FV intake among children (RQ4)? Methods: This is a secondary analysis of a study using a randomized controlled trial, with 4 groups (each n = 100 child-parent dyads). All groups were analyzed together for this paper since groups did not vary on components relevant to our analysis. All children and parents (n = 400 dyads) received a self-regulation serious game intervention and parent material. The intervention ran for three months. Measurements were taken at baseline, immediately after intervention and at 3-month follow-up. Asking behavior and home FV availability were measured using questionnaires; child FV intake was measured using 24-h dietary recalls. ANCOVA methods (research question 1), linear mixed-effect models (research question 2), and Structural Equation Modeling (research questions 3 and 4) were used. Results: Baseline child asking behaviors predicted baseline home FV availability. The intervention increased child asking behaviors and home FV availability. Increases in child asking behaviors, however, did not predict increased home FV availability. Increased child asking behaviors and home FV availability also did not mediate the increases in child FV intake. Conclusions: Children influence their home FV environment through their asking behaviors, which can be enhanced via a serious game intervention. The obtained increases in asking behavior were, however, insufficient to affect home FV availability or intake. Other factors, such as child preferences, sample characteristics, intervention duration and parental direct involvement may play a role and warrant examination in future research

An investigation into the gel characteristics of xanthan gum-locust bean gum mixes.

Xanthan gum and locust bean gum are two naturally occurring polysaccharides which do not form gels in isolation, but undergo a positive synergy to form thermoreversible elastic gels in combination. The aim of this project was to investigate the interaction between the two polysaccharides and factors affecting the gel characteristics of the mixes, with a view to developing their pharmaceutical uses. The individual polysaccharides were characterised using flame emission spectrometry and nuclear magnetic resonance spectroscopy for xanthan gum and fractionation for locust bean gum. The gel strengths of the mixed systems were studied using oscillatory rheology and texture analysis with respect to temperature, fractionated locust bean gum and the inclusion of either sodium chloride or sucrose as additives. Conformational changes of xanthan gum which are thought to contribute to the mechanism of the interaction were studied using a combination of high sensitivity differential scanning calorimetry and synchrotron circular dichroism. The findings from these studies led to the development of methods for formulating controlled release tablets using a wet granulation process. The results show that maximum synergy occurs for the 1:1 ratio between xanthan gum and locust bean gum, in which the gelation process is temperature dependent and is enhanced by heating and cooling between 20°C to 90°C. The effects of sucrose and locust bean gum fractions with a high mannose:galactose ratio increase the gel strength, whereas the inclusion of sodium chloride has no effect on the gel strength of xanthan gum-locust bean gum mixes. The thermoanalysis techniques used to determine xanthan gum conformation suggest that xanthan gum interacts with locust bean gum both in the disordered coil and ordered helical forms. These findings were employed for the formulation studies, which showed that xanthan gum conformation which is affected by different factors, depends upon an aqueous environment which in turn affects the synergy with locust bean gum and hence the release properties from the gel matrix. This work suggests that the techniques chosen for this project are highly complimentary and a useful approach for studying the behaviour of mixed polysaccharide gel systems, which may exhibit different properties when formulated into tablet dosage forms

Enrichment of tomatoes and broccoli with specific bioactives for the reduction of prostate carcinogenesis

Epidemiological studies have linked high consumption of tomatoes and cruciferous vegetables to decreased risk of prostate cancer. Several bioactive components isolated from cruciferous vegetables and tomatoes exhibit anti-cancer properties. Previous studies have evaluated the cancer preventive potential of these individual bioactives, but few have examined them within the context of a whole food. In a pilot study to evaluate bioactivity of different tomato and broccoli powders, male Copenhagen rats were fed diets containing 10% standard tomato powder, tomato enriched with lycopene or total carotenoids, standard broccoli floret, broccoli sprouts, or broccoli enriched with indole glucosinolates or selenium for 7 days. All broccoli diets increased activity of colon quinone reductase (NQO1). Indole glucosinolate-enriched broccoli and selenium-enriched broccoli increased hepatic NQO1 and cytochrome P450 1A activity (P < 0.05). Different tomato diets resulted in altered hepatic accumulation of lycopene, phytofluene, and phytoene. These results demonstrate that the bioactive content of vegetables affects both tissue content of bioactives and activity of detoxification enzymes. Enhancing bioactive content of tomatoes and broccoli may enhance efficacy in the prevention of prostate cancer. Based on the results of this pilot study, our next objective was to determine if standard broccoli or the indole glucosinolate-enriched (IG) broccoli, would impact prostate carcinogenesis in the aggressive TRAMP model. Male mice were randomized into 3 diet groups at 5-7 weeks of age: AIN-93G control, 10% control broccoli powder, or 10% IG broccoli powder. Diets were fed throughout the study until termination at 20 weeks of age, with no differences in body weight or food intake observed between groups. There were no differences between groups in genitourinary tract weight, a surrogate marker of tumor volume, and no differences were found in cancer grade upon histopathologic evaluation indicating that broccoli feeding did not impact cancer aggressiveness. The horticultural manipulation of broccoli to alter phytochemical concentration is a feasible approach to optimizing the potential for cancer prevention, yet optimal patterns of phytochemicals remain to be characterized. To assess potential epigenetic effects of lycopene, we examined the effects of lycopene and its metabolite, apo-10’-lycopenal, on methylation of the GSTP1 promoter in LNCaP cells. GSTP1 is hypermethylated in >90% of prostate cancers, which results in complete silencing of the gene. Neither lycopene nor apo-10’-lycopenal altered mRNA expression or DNA methylation of GSTP1 indicating that lycopene is not an effective demethylating agent for this gene in this particular prostate cancer cell line. It remains to be seen if lycopene has epigenetic effects on other genes or in other cell lines. Overall we have demonstrated that the bioactive content of tomatoes and broccoli can be altered through agronomic means, but optimal profiles for cancer prevention remain to be determined. Much remains to be learned about how tomatoes and broccoli alter cancer progression at different stages and the mechanisms through which they exert their effects

New Bioenergy Yeast Is an Overachiever

There\u27s a lot that can be done with a corn cob after the kernels have been removed. Farmers leave the cobs on the field to boost soil quality. Enterprising cooks use the cobs to make jelly. In China, the sugar xylose is extracted from the cob for industrial uses. Liu worked with technician Scott Weber and supervisory microbiologist Michael Cotta on this project. All three researchers are in the Bioenergy Research Unit at the National Center for Agricultural Utilization Research in Peoria, Illinois. The team started the project with a strain of yeast that had been identified in earlier studies on the use of sweet sorghum as a biofeedstock for ethanol production. Then, in the laboratory, they placed this strain in environments that would promote the expression of genetic traits that favor SSF, including adapting to higher temperatures and tolerating cob-derived compounds that interfere with ethanol production. This resulted in the selection of Y-50464. The team compared how quickly Y-50464 and another yeast strain, Y-12632, could release and ferment the sugar in corn cob residues after the xylose had been extracted. Liu’s star newcomer yeast was able to grow and reach its highest cell density in less than 24 hours after the test began. The comparison yeast didn’t grow at all