How different are the indicatrixes of the leaves of various woody plant species?

Some researchers assume that the light reflection from leaves is Lambertian, but I verify that some leaves exist showing no Lambertian reflection. One can measure the indicatrixes of leaves of various woody plant species by the use of a goniophotometer. Minnaert constants can be calculated from these indicatrixes for quantitative evaluation. I discuss why light scattering from leaves does not always obey Lambertian law.     

Why are carbon nanotubes fast transporters of water?

Extraordinarily fast transport of water in carbon nanotubes (CNTs) in recent experiments has been generally attributed to the smoothness of the CNT surface. Using molecular dynamics simulations we investigate water flow in (16,16) CNTs and show that the enhanced flow rates over Hagen-Poiseuille flow arise from a velocity "jump" in a depletion region at the water nanotube interface and that the water orientations and hydrogen bonding at the interface significantly affect the flow rates. For nanotube with the same smooth wall structure but with more hydrophilic Lennard-Jones (LJ) parameters of silicon, the enhancement is greatly reduced because it does not have "free" OH bonds pointing to the wall as in CNTs that would reduce the number of hydrogen bonds in the depletion layer. Roughness in the tube walls causes strong hydrogen-bonding network and no significant flow enhancement is attained in rough tubes.     

How well are color components of samples of the Natural Color System estimated?

The aim of this study was to determine how accurately color-normal subjects that have received basic information about, but do not have practical experience with, the Natural Color System (NCS) can estimate the Heringian components of a representative selection of samples. Twenty-five color-normal subjects, taking part in two trials with at least a 24 h gap between assessments, selected four samples representing individual unique hues (uHs) from a set of 40 highly chromatic NCS samples on a rotatable tray. The samples selected for assessment of components were displayed to the subjects who estimated the hue components of 16 high-chroma samples, hue and white/black components of 16 tonal color samples, and three achromatic samples with different blackness values. Variability in selection of samples representing uHs as well as the relationship between the subjects' estimates of unique hue components and the defined values of the system was obtained. It was found that hues alone are easier to correctly estimate than hues together with white and black and that the components of colors of higher chroma are easier to estimate accurately than those of lower chroma. It was also found that, for R and G, the mean uH choices of subjects differed very little from the NCS's R and G, whereas selections for yellow and blue deviated, the former by 1.22 hue steps (slightly greener than G90Y), and the latter by 1.36 hue steps (represented approximately by R85B). This may impact the accuracy of color models that employ NCS unique hues.     

Does safety climate predict safety performance in Italy and the USA? Cross-cultural validation of a theoretical model of safety climate

Previous studies have acknowledged the relevance of assessing the measurement equivalence of safety related measures across different groups, and demonstrating whether the existence of disparities in safety perceptions might impair direct group comparisons. The Griffin and Neal (2000) model of safety climate, and the accompanying measure (Neal et al. [NGH], 2000), are both widely cited and utilized. Yet neither the model in its entirety nor the measure have been previously validated across different national contexts. The current study is the first to examine the NGH measurement equivalence by testing whether their model of safety climate predicting safety performance is tenable in both English speaking and non-English speaking countries. The study involved 616 employees from 21 organizations in the US, and 738 employees from 20 organizations in Italy. A multi-group confirmatory factor analytic approach was used to assess the equivalence of the measures across the two countries. Similarly, the structural model of relations among the NGH variables was examined in order to demonstrate its cross-country invariance. Results substantially support strict invariance across groups for the NGH safety scales. Moreover, the invariance across countries is also demonstrated for the effects of safety climate on safety knowledge and motivation, which in turn positively relate to both compliance and participation. Our findings have relevant theoretical implications by establishing measurement and relational equivalence of the NGH model. Practical implications are discussed for managers and practitioners dealing with multi-national organizational contexts. Future research should continue to investigate potential differences in safety related perceptions across additional non-English speaking countries.     

Should we believe model predictions of future climate change?

Predictions of future climate are based on elaborate numerical computer models. As computational capacity increases and better observations become available, one would expect the model predictions to become more reliable. However, are they really improving, and how do we know? This paper discusses how current climate models are evaluated, why and where scientists have confidence in their models, how uncertainty in predictions can be quantified, and why models often tend to converge on what we observe but not on what we predict. Furthermore, it outlines some strategies on how the climate modelling community may overcome some of the current deficiencies in the attempt to provide useful information to the public and policy-makers.     

How much do different ways of calculating percentiles influence the derived performance indicators? A case study

Bibliometric indicators can be determined by comparing specific citation records with the percentiles of a reference set. However, there exists an ambiguity in the computation of percentiles because usually a significant number of papers with the same citation count are found at the border between percentile rank classes. The present case study of the citations to the journal Europhysics Letters (EPL) in comparison with all physics papers from the Web of Science shows the deviations which occur due to the different ways of treating the tied papers in the evaluation of the percentage of highly cited publications. A strong bias can occur, if the papers tied at the threshold number of citations are all considered as highly cited or all considered as not highly cited.     

Application of sediment conservation health diagnosis indicators in watersheds—example of the Taipei water source domain

Health diagnosis indicators including runoff ratio, denudation depth, vegetation cover ratio, turbidity, and sediment concentration were used to assess sediment conservation problems in the Taipei Water Source Domain. Apart from comparing the health of various sub-watersheds based on health indicators, reference values of health indicators were determined and used to assess changes in the health of individual sub-watersheds. According to the results, the average runoff ratios during dry season at the Feitsui Reservoir and Quchi gauging station were 1.15 and 0.76, which indicated the area has excellent water retention capacity. The denudation depth in the Zhakong River sub-watershed, the chief source of sediment in the watershed, was 1.22 cm/year. A forest cover ratio of 92.59% throughout the whole watershed indicated vegetation cover was generally very good. Turbidity and sediment concentration at the Fushan station were higher than those at other stations, and commonly soared after typhoons or torrential rains, which affected downstream tap water quality. In summary, the whole watershed has excellent water retention capacity and good vegetation cover; the chief problem is the presence of landslides in the Zhakong River sub-watershed, which causes downstream turbidity to soar in the wake of typhoons and torrential rains.     

How accurate are policy document mentions? A first look at the role of altmetrics database

Scientometrics - Policy document mention is considered to indicate the significance and societal impact of scientific product. However, the accuracy of policy document altmetrics data needs to be...     

Simulation of the pressure drop across granulated mixtures using a coupled DEM – CFD model

The sinter process converts mixtures of iron ore, iron ore fines and fluxes into a fused aggregate (sinter) that is used as burden material in the blast furnace. The rate of this process is predicted by measuring the pressure drop across the green granulated mixture before ignition. A lower pressure drop corresponds with a higher permeability resulting in a higher sinter rate. The addition of fine material, such as concentrate or concentrate agglomerated into micropellets, to the sinter mixture affects the pressure drop. This study numerically predicts the pressure drop over several granulated mixtures in order to reduce the number of experimental measurements. The pressure drop was studied both experimentally using a pot grate and by coupled DEM (Discrete Element Method) – CFD (Computational Fluid Dynamics) simulations. The validation of the model was performed by comparing the measured and numerical values of the pressure drop across glass beads 3 and 6?mm in diameter respectively. The simulation of the pressure drop was extended to granulated mixtures that contain 0–40% concentrate or micropellets. DEM was also used to numerically simulate iron ore granules and relate their mechanical behaviour to particle size distribution, shape, friction coefficient, Young’s modulus and adhesion force.     

How does the normalization of data affect the ARWU ranking?

The aim of this paper is to present new ideas in evaluating Shanghai University??s Academic Ranking of World Universities (ARWU). In particular, this paper shall try to determine whether the normalization of data affects University ranks. In accordance with this, both the normalized and original (raw) data for each of the six variables has been obtained. Based on a sample containing the 54 US universities which are placed in the ARWU top 100, the statistical I-distance method was performed. The results showed great inconsistencies between university ranks obtained for the original and normalized data. These findings were then analyzed and the universities that had the greatest fluctuation in their ranks were noted.     

How realistic are older drivers’ ratings of their driving ability?

One strategy that can be used by older drivers to guard against age-related declines in driving capability is to regulate their driving. This strategy presumes that self-judgments of driving capability are realistic. We found no significant relationships between older drivers’ hazard perception skill ratings and performance on an objective and validated video-based hazard perception test, even when self-ratings of performance on specific scenarios in the test were used. Self-enhancement biases were found across all components of driving skill, including hazard perception. If older drivers’ judgments of their driving capability are unrealistic, then this may compromise the effectiveness of any self-restriction strategies to reduce crash risk.     

How accurate are news mentions of scholarly output? A content analysis

Scientometrics - News mentions are considered as useful source for measuring the societal impact of scholarly output, meanwhile data quality plays a fundamental role in its research and...     

How to evaluate the degree of interdisciplinarity of an institution?

The Stirling index of the set of references of the corpus documents is widely used in the literature on interdisciplinary research and is defined as the integration score of the corpus under study. Such an indicator is relevant at the scale of a research institution, however, there is a gap between the integration scores of individual documents, and a global score computed on the whole set of references. The difference between the global index and the average of individual document indexes carries another relevant information about the corpus: it measures the diversity between the reference profiles of the corpus documents. It is, therefore, named between article index whereas the average of the individual article indexes is called within article index. The statistical properties of these two indexes as well as of the global index are derived from a general approximation method for distributions and lead to statistical tests which can be used to make meaningful comparisons between an institution indexes and benchmark values. The two dimensions of the global index provide a more acute information on the interdisciplinary practices of an institution researchers in a given research domain and is, therefore, likely to contribute to strategic and management issues.     

How well developed are altmetrics? A cross-disciplinary analysis of the presence of ‘alternative metrics’ in scientific publications

In this paper an analysis of the presence and possibilities of altmetrics for bibliometric and performance analysis is carried out. Using the web based tool Impact Story, we collected metrics for 20,000 random publications from the Web of Science. We studied both the presence and distribution of altmetrics in the set of publications, across fields, document types and over publication years, as well as the extent to which altmetrics correlate with citation indicators. The main result of the study is that the altmetrics source that provides the most metrics is Mendeley, with metrics on readerships for 62.6 % of all the publications studied, other sources only provide marginal information. In terms of relation with citations, a moderate spearman correlation (r = 0.49) has been found between Mendeley readership counts and citation indicators. Other possibilities and limitations of these indicators are discussed and future research lines are outlined.     

Patents as indicators of the technological position of countries on a global level?

Scientometrics - The technological capabilities of a country play a key role in identifying paths to economic growth and development. Policymakers have a special interest in understanding the...     

A maximum dissipation thermodynamic multi-scale model for the dynamic response of the arterial elastin–water system

The mechanical response of the elastin–water system in an artery wall is viscoelastic. Elastin in vivo must operate in the rubbery region, i.e., above the glass transition, that depends on moisture content. A dynamic multi-scale time-dependent evolution equation is presented for the mechanical response of the elastin–water system that captures the effect of moisture content on the glass transition of the elastin. To define non-equilibrium evolution processes, the construction requires only a hyperelastic strain energy density function describing the long-term behavior and the thermodynamic relaxation modulus that describes the relaxation speed of non-equilibrium processes. The thermodynamic relaxation modulus also relates spatial scales, the molecular scale including moisture bonding to the bulk material scale. The model reproduces published experimental data on the elastin glass transition behavior with respect to load frequency and to ambient relative humidity but is not merely empirical in the sense of being a fit to such data because it predicts dynamic responses such as non-physiological creep and physiological rate-dependent stress–stretch relations. The new viscoelastic model predicts the influence of moisture content and the glass transition of the elastin on the time-dependent response of the circumferential stretch and the change in radius of a hydrated arterial cylindrical elastin lamella under cyclic radial pressure loads in the hemodynamic range. Such an elastin cylinder approximates the behavior of the elastin substructure in an elastic artery wall.     

How are collaboration and productivity correlated at various career stages of scientists?

Collaboration is believed to be influential on researchers’ productivity. However, the impact of collaboration relies on factors such as disciplines, collaboration patterns, and collaborators’ characters. In addition, at different career stages, such as the growth or the establishment career stages of scientists, collaboration is different in scale and scope, and its effect on productivity varies. In this paper, we study the relationships between collaboration and productivity in four disciplines, Organic Chemistry, Virology, Mathematics and Computer Science. Our study found that the productivity is correlated with collaboration in general, but the correlation could be positive or negative on the basis of which aspect of collaboration to measure, i.e., the scale or scope of the collaboration. The correlation becomes stronger as individual scientists progress through various stages of their career. Furthermore, experimental disciplines, such as Organic Chemistry and Virology, have shown stronger correlation coefficients than theoretical ones such as Mathematics and Computer Science.     

How big is the linear region of irreversible thermodynamics?

The driving forces of diffusion reach their largest values in thin films. Temperature and voltage gradients may be steep simply because the film is thin.The matter and energy fluxes of diffusion contain, in principle, a whole series of cross terms. Commonly, we take only first order terms and ignore those of second and higher order; we restrict ourselves to “small” temperature and voltage gradients, to “the linear region of irreversible thermodynamics”.But how big is “small”? The present paper proposes that the linear region of irreversible thermodynamics extends from complete equilibrium to limits in which the energy change in the carrier system (e.g. phonons or plasmons), over a distance of one mean free path along the energy gradient, is comparable with the total energy in the carrier system. If the energy is E and the mean free path is λ, the limit occurs when

$\text{λ▽E}\text{E→1}$

Within this limit, experiments in thermomigration and electromigration measure equilibrium properties. The “reduced heat of transport” of a crystal defect is rigorously identified as the thermal energy of the defect structure.     

How can graphene reduce the flammability of polymer nanocomposites?

Nanocomposites based on poly(vinyl alcohol) (PVA) and graphene nanosheets have been prepared by polymer solution blending and their flame retardant properties have been evaluated by a cone calorimetry test. It has been shown that there is a strong influence of graphene nanosheets on the fire behaviour of the composites with a significant reduction in peak heat release rate (PHRR) and a much longer time to ignition. Compared to pure PVA, the PHRR of PVA filled with 3 wt.% graphene is reduced by 49%. The flame retardancy of graphene for PVA matrix surpasses that of both Na-MMT and MWNTs with the same addition content. Such a remarkable behaviour might be explained by the forming of a compact, dense and uniform char during combustion.     

How accurately does Thomas Kuhn’s model of paradigm change describe the transition from the static view of the universe to the big bang theory in cosmology?

Up to the 1960s the prevalent view of science was that it was a step-by-step undertaking in slow, piecemeal progression towards truth. Thomas Kuhn argued against this view and claimed that science always follows this pattern: after a phase of “normal” science, a scientific “revolution” occurs. Taking as a case study the transition from the static view of the universe to the Big Bang theory in cosmology, we appraised Kuhn’s theoretical approach by conducting a historical reconstruction and a citation analysis. As the results show, the transition in cosmology can be linked to many different persons, publications, and points in time. The findings indicate that there was not one (short term) scientific revolution in cosmology but instead a paradigm shift that progressed as a slow, piecemeal process.