Scientometrics - We analyzed breakthrough patents that serve as the basis of emerging technological trajectories and paradigm over 25-years. The results showed that although technological fields... 相似文献
This paper discusses the current state-of-the-art with respect to impact assessment and cost-benefit analysis of measures designed to improve safety or mobility for pedestrians and cyclists. The study concludes that a number of impacts that are likely to regarded as important for pedestrians and cyclists are not included in current impact assessments and cost-benefit analyses as these are made in Norway. Impacts that are not currently included in impact assessments and cost-benefit analyses are: (a) changes in the amount of walking and cycling; (b) changes in travel time for pedestrians and cyclists; (c) changes in road user insecurity (feeling of safety); and (d) changes in road user health state. In order to include these effects in impact assessments and cost-benefit analyses, more needs to be known about their occurrence and monetary value. Hypothetical examples of ideally designed cost-benefit analyses are given, based on highly preliminary monetary values for travel time, insecurity and generalised costs of travel for pedestrians and cyclists. These analyses indicate that inclusion of these effects in cost-benefit analyses could make a major difference for the results of those analyses. 相似文献
A detailed evaluation of the analytical characteristics of a particle beam/hollow cathode glow discharge atomic emission spectroscopy (PB/HC-AES) system is described for applications in the area of organic sample analysis. The optimization of sample introduction, nebulization parameters, and glow discharge conditions was performed for the elemental analysis (focusing on C and H) of a group of amino acids. By use of a high-efficiency thermoconcentric nebulizer, analyte particles are introduced into a heated hollow cathode glow discharge source, in either flow injection or continuous-flow mode, for subsequent vaporization/atomization and excitation. Nebulization temperature, solvent composition, and liquid flow rate were studied to elucidate their roles in the ultimate analyte emission characteristics for organic compound analysis. The hollow cathode operating discharge current and gas pressure were optimized, with the general responses found to be similar to those for the case of metal analysis. Background interferences from solvent and additive media on carbon and hydrogen determinations were studied and substantially reduced. The analytical response curves for carbon and hydrogen present in amino acids were obtained using 200 μL injection volumes, showing less than 10% RSD for replicate injections over a concentration range of 10-250 ppm, with detection limits of 3 and 1 ppm, respectively, for C (I) and H (I) emission. Subsequent studies of the response of carbon and hydrogen emission signal intensities to differences in amino acid stoichiometries suggest a capability of the PB/HC-AES system for the determination of empirical formulas based on H (I)/C (I) intensity ratios. 相似文献
Pharmaceutically active compounds (PhACs) in the environment lately have been acknowledged to constitute a health risk for humans and terrestrial and aquatic ecosystems. Human and veterinary applications are the main sources of PhACs in the environment and the major pathways are excretion and discharge to the environment through sewage treatment plants (STPs). In this study, the occurrence and fate of selected human PhACs belonging to different therapeutic classes (non-steroidal anti-inflammatory drugs, lipid regulators, anti-epileptics, antibiotics and beta-blockers) were investigated in a small river in the very south of Sweden. The objectives of the study were to evaluate the impact of a high and rather constant load in sewage influent on downstream concentrations and whether substances that are metabolized to a high degree in humans also show a low persistency in a natural aquatic environment. Water samples were collected from the influent and effluent of the STP, in a series of dammed reservoirs leading to discharge into the H?je River in Sweden, and at several locations in the river downstream of the outfall. After enrichment by solid-phase extraction, the compounds were analyzed using GC-MS (methylated derivatives) or LC-MS/MS. In addition to the targeted pharmaceuticals, GC-MS analysis of the samples revealed the presence of other sewage-related pollutants (triclosan, caffeine, flame-retardants, antioxidants) and these results where included for comparison. Removal efficiencies were calculated in the STP and found to display a wide range with numerous species surviving treatment at greater than half their influent concentrations, including diclofenac, the anti-epileptic carbamazepine, a beta-blocker (propanolol), and antibiotics trimetoprim and sulfamethoxazole. Low removals were also observed for Tris(2-chloroisopropyl)phosphate (flame retardant), BHT-aldehyde (oxidation product of BHT) and synthetic musk (HHCB). The concentrations of chloride (Cl(-)) and boron (B) were used as natural inert tracers to estimate the relative extent of dilution of PhACs measured in the effluent of the STP on concentrations measured further downstream. Based on spatial trends of concentrations (recalculated to reflect a hypothetical scenario with no dilution), ibuprofen, ketoprofen, naproxen and dicofenac were shown to be subject to significant abiotic or biotic transformations or physical sequestration in the river. The beta-blockers atenolol, metoprolol and propanolol, the antibiotics trimetoprim and sulfametoxazole, and carbamazepine demonstrated a high degree of persistence. Fluctuations in the concentration of carbamazepine and gemfibrozil were observed along the series of reservoirs and within the river and are hypothesized to be due to release of parent compound from glucuronides. Several of the investigated substances (metaprolol, propanolol and carbamazepin) that exhibit low excretion rates as parent compounds demonstrate a surprising persistence in the aquatic environment. It is concluded that pharmaceutical substances with a high metabolic rate in humans (low excretion rate) do not necessarily induce a short lifetime in aquatic environments. Results from this study emphasize the need for a broader view on the concept of persistence that accounts for loading rates, in addition to removal mechanisms (e.g., transformation, volatility and physical sequestration by solids), under a variety of spatial and temporal scales. 相似文献
We discuss the accuracy limits for the localization of surfaces in three-dimensional (3-D) space. Such a localization is necessary for the registration of different views of an object, taken by 3-D sensors from several directions. A quantitative analysis shows that the lateral localization accuracy of a small surface area is proportional to the local curvature of the surface. This confirms the intuitive conjecture that our visual system performs localization of 3-D objects via sharp features. The longitudinal localization accuracy depends only on the noise of the data and is usually much better than the lateral localization accuracy, suggesting that surfaces are to be registered only along the longitudinal directions. 相似文献
Can the ubiquitously magnetic solar atmosphere have any effect on solar global oscillations? Traditionally, solar atmospheric magnetic fields are considered to be somewhat less important for the existence and characteristic features of solar global oscillations (p,f and the not-yet-observed g-modes). In this paper, I demonstrate the importance of the presence of magnetism and plasma dynamics for global resonant oscillations in the solar atmosphere. In particular, in the lower part of the solar atmosphere there are both coherent and random components of magnetic fields and velocity fields, each of which contribute on its own to the line widths and frequency variations of solar global acoustic waves. Changes in the coherent large-scale atmospheric magnetic fields cause frequency shifts of global oscillations over a solar cycle. The random character of the continuously emerging, more localized, magnetic carpet (i.e. small-scale, possibly even sub-resolution, loops) gives rise to additional frequency shifts. On the other hand, random and organized surface and sub-surface flows, like surface granulation, meridional flows or differential rotation, also affect the coupling mechanism of global oscillations to the lower magnetic atmosphere. The competition between magnetic fields and flows is inevitable. Finally, I shall discuss how solar global oscillations can resonantly interact with the overlaying inhomogeneous lower solar atmosphere embedded in a magnetic carpet. Line width broadening and distorsion of global acoustic modes will be discussed. The latter is suggested to be tested and measured by using ring-analysis techniques. 相似文献
Forty years ago Helfferich and Peterson published an article in Science regarding a "paradoxical" behavior in nonlinear chromatography (Helfferich, F.; Peterson, D. L. Science 1963, 142, 661-662). They theoretically predicted that when an excess of sample molecules is injected into a chromatographic column that is equilibrated with a constant stream of identical molecules, the observed peak will not contain the injected molecules. Instead the observed peak will only contain molecules from the stream whereas the injected molecules will exit the column in a slower moving, "invisible" peak. They considered it paradoxical that a single injection in a single-component system could cause the successive elution of two peaks (Helfferich, F. J. Chem. Educ. 1964, 41, 410-413). In this study, the paradox is experimentally proven for the first time. Two different strategies were employed: (i) a radiochemical approach and (ii) a method based on the use of two enantiomers in a nonchiral separation system. The experiments were compared with computer simulations. 相似文献
Photosensitivity designates the ability to permanently change the refractive index of a glass by optical processing. The phenomenon allows the fabrication of numerous phase structures, the simplest of which is the Bragg grating obtained by photoimprinting a periodic index modulation within the material. Bragg gratings have changed the way in which optical fibre (or planar waveguide) lasers are now used. Distributed Bragg Reflector (DBR) or Distributed Feed Back (DFB) lasers, when intracore Bragg gratings are used for linear cavity feedback, are commonly fabricated in rare earth doped optical silica-based fibres. On the other hand, photosensitivity can also result in effects which can prove to be detrimental to the fabrication of miniature coherent light sources. The paper will cover some of the advances that have been made in improving the photosensitivity of inorganic glasses, in searching new photosensitive materials and in characterizing Bragg grating properties relevant to laser applications. 相似文献
The published data on the biokinetic behaviour of 27 14C-labelled compounds in humans or animals have been reviewed. Effective doses have been calculated for those compounds for which this information had not been published and doses have been compared to that calculated with the International Commission on Radiological Protection (ICRP) default model for carbon compounds of unknown composition. The compound-specific effective doses for a few natural human biochemical substrates are quite close to the ICRP default dose coefficient, but for the remainder of the compounds considered the doses are smaller by factors ranging from about 5 to 200. Comparison of the dosimetric data suggests that although the ICRP default model will overestimate the dose for very many compounds it could remain useful as a guide for general prospective radiological protection purposes. However, a comparison of the biokinetic information indicates that the ICRP default model would not be reliable for the interpretation of bioassay data. 相似文献
This research empirically analyzes the impact of digital inclusive finance on urban economic vitality in Yangtze River Delta, China. The findings are as follows. 1) The development of digital inclusive finance significantly boosts the economic vitality of urban areas. 2) The promotion effect of digital finance on urban economic vitality varies regionally, as such vitality is more strongly impacted by the overall degree of digital inclusive finance development in core areas than it is by that in non-core areas. 3) The economic impact of digital inclusive finance has a clear spatial spillover, whereby an increase in digital financial inclusion in one region boosts the economic vitality of neighboring regions. 4) The total levels of innovation and entrepreneurship, entrepreneurial activity, and innovation activity all have a double threshold effect in the threshold model, indicating that digital inclusive finance has a leapfrog-promoting influence on urban economic vitality via an increase in innovation and entrepreneurship levels. Future developments in digital technology should therefore be fully embraced, and the state of inclusive digital finance should be enhanced. Governments and relevant authorities can target to advance the leadership roles of innovation and entrepreneurship and raise the contribution of mass entrepreneurship and innovation to urban economic growth. 相似文献
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. 相似文献
In this paper, impurity parameters mi and ki have been calculated for a range of impurities I as detected in the eutectics Co?CC and Pt?CC, by means of the software package Thermo-Calc within the ternary phase spaces Co?CC-I and Pt?CC-I. The choice of the impurities is based upon a selection out of the results of impurity analyses performed for a representative set of samples for each of the eutectics in study. The analyses in question are glow discharge mass spectrometry (GDMS) or inductively coupled plasma mass spectrometry (ICP-mass). Tables and plots of the impurity parameters against the atomic number Zi of the impurities will be presented, as well as plots demonstrating the validity of van??t Hoff??s law, the cornerstone to this study, for both eutectics. For the eutectics in question, the uncertainty u(TE ? Tliq ) in the correction TE ? Tliq will be derived, where TE and Tliq refer to the transition temperature of the pure system and to the liquidus temperature in the limit of zero growth rate of the solid phase during solidification of the actual system, respectively. Uncertainty estimates based upon the current scheme SIE?COME, combining the sum of individual estimates (SIE) and the overall maximum estimate (OME) are compared with two alternative schemes proposed in this paper, designated as IE?CIRE, combining individual estimates (IE) and individual random estimates (IRE), and the hybrid scheme SIE?CIE?CIRE, combining SIE, IE, and IRE. 相似文献
We consider the “Matthew effect” in the citation process which leads to reallocation (or misallocation) of the citations received
by scientific papers within the same journals. The case when such reallocation correlates with a country where an author works
is investigated. Russian papers in chemistry and physics published abroad were examined. We found that in both disciplines
in about 60% of journals Russian papers are cited less than average ones. However, if we consider each discipline as a whole,
citedness of a Russian paper in physics will be on the average level, while chemistry publications receive about 16% citations
less than one may expect from the citedness of the journals where they appear. Moreover, Russian chemistry papers mostly become
undercited in the leading journals of the field. Characteristics of a “Matthew index” indicator and its significance for scientometric
studies are also discussed. 相似文献
Aragonite pearl, vaterite pearl and shell nacre of the freshwater mollusc Hyriopsis cumingii (Zhejiang province, China) were chosen to analyze microstructure and organic composition in the different habits of calcium carbonate. SEM and TEM were used to reveal the microstructure and mineralogical phase. We found that tablets in vaterite exhibited more irregular texture and were packaged with more organic matrices than in aragonite forms. Then a peculiar method was introduced to extract water soluble matrix (WSM), acid soluble matrix (ASM) and acid insoluble matrix (AIM) from the three samples, and biochemical analysis of these organic matrixes involved in crystal formation and polymorph selection was carried out. High performance liquid chromatography (HPLC) confirms the hydrophobic pattern of the organic matrix intermingled with mineral, the opposite of the early mobilizable water soluble fraction. Amino acid composition confirms hydrophobic residues as major components of all the extracts, but it reveals an imbalance in acidic residues rates in WSM vs. ASM and in aragonite vs. vaterite. Electrophoresis gives evidence for signatures in proteins with a 140 kDa material specific for aragonite in WSM. Conversely all ASM extracts reveal the presence of about 55 kDa components, including a discrete band in vaterite extract. 相似文献
The metal—organic frameworks (MOFs) are expected as ideal biomimetic enzymes for colorimetric glucose detection because of their large surface areas, well defined pore structures, tunable chemical composition, and multi-functional sites. However, the intrinsically chemical instability and low mimetic enzyme activity of MOFs hinder the application of them in imitating the enzyme reactions. In this work, we demonstrated a metal-MOF synergistic catalysis strategy, by loading Pt nanoparticles (Pt NPs) on MIL-88B-NH2 (Fe-MOF) to increase peroxidase-like activity for the detection of glucose. The induced electrons transfer from Pt atom to Fe atom accelerated the redox cycling of Fe3+/Fe2+, improved the overall efficiency of the peroxidase-like reaction, and enabled the efficient and robust colorimetric glucose detection, which was proved by both experiments and density functional theory (DFT) calculation. Additionally, the sensitivity and chemical stability of this synergistic effect strategy to detect the glucose are not affected by the complex external factors, which represented a great potential in fast, easy, sensitive, and specific recognition of clinical diabetes.
The sliced Bottle Manikin Absorber (BOMAB) phantom was originally proposed as an alternative to a commercially available phantom, but it suffers from the disadvantage of containing over 160 sources that need to be manufactured; however, it was found that the number of slices could be reduced substantially and that two slices in the sliced phantom gave the same performance characteristics over a wide energy range as a conventional BOMAB phantom for a particular counting system. This work explores the adaptability of this phantom to another counting geometry. The response of the Human Monitoring Laboratory's whole-body counter measuring this phantom with a decreasing number of planar sources has been modelled using MCNP5 over a wide energy range (122-2754 keV). It was found that the best agreement was obtained when the phantom contained 10 sources, 1 in the mid point of each section. As this is a different result from a previous finding, any other counting geometry will have to be assessed to determine the optimum loading if the sliced phantom is to be used. Also, it is clear that this type of phantom cannot be used for an intercomparison that will encounter different counting geometries, unless it contains a full loading of sources. 相似文献
AbstractIn this paper, we examine whether the innovativeness of knowledge intensive business services (KIBS) firms is affected by their inherently high rate of interactions with clients and partners. Even if such firms do not deliberately follow an open innovation strategy, they are exposed to knowledge flows from other organisations. A particularly interesting issue is the connection between openness and the need to develop dynamic capabilities for distinct phases of knowledge processing. Building on resource-based views, we have developed hypotheses on the respective importance of KIBS firms’ dynamic capabilities and their inclination to engage in open innovation. Since clients and partners can contribute to activities especially at the beginning and end of the innovation value chain, KIBS should consider focusing on developing a ‘conceptualizing’ capability for translating raw ideas into marketable service propositions. The importance of this capability is confirmed by our regression analyses on survey data from 125 KIBS in the Netherlands. By contributing to the literature on KIBS and open innovation, we shed light on strategically balancing capability development and external capability sourcing. 相似文献
Multiple studies report that male scholars cite publications of male authors more often than their female colleagues do—and vice versa. This gender homophily in citations points to a fragmentation of science along gender boundaries. However, it is not yet clear whether it is actually (perceived) gender characteristics or structural conditions related to gender that are causing the heightened citation frequency of same-sex authors. A bibliometric study on the two leading German communication science journals Publizistik and Medien & Kommunikationswissenschaft was employed to further analyze the causes of the phenomenon. As scholars tend to primarily cite sources from their own area of research, differences among male and female scholars regarding their engagement in certain research fields become relevant. It was thus hypothesized that the research subject might mediate the relationship between the citing and cited authors’ genders. A first analysis based on n = 917 papers published in the period from 1970 to 2009 confirmed the expected gender-differences regarding research-activity in certain fields. Subsequently, structural equation modeling was employed to test the suggested mediation model. Results show the expected mediation to be a complementary one indicating that gender homophily in citations is partly due to topical boundaries. While there are alternative explanations for the remaining direct effect, it may suggest that a fragmentation of science along gender boundaries is indeed an issue that communication science must face. 相似文献
Accident data play an important role in vehicle safety development. Accident data sources are generally limited in terms of how much information is provided on driver states and behaviour prior to an accident. However, the precise limitations vary between databases, due to differences in analysis focus and data collection procedures between organisations. If information about a specific accident can be retrieved from more than one data source it should be possible to combine the available information sets to facilitate data from one source to compensate for limitations in the other(s). To investigate the viability of such compensation, this study identified a set of accidents recorded in two different data sources. The first data source investigated was an accident mail survey and the second data source insurance claims documents consisting predominantly of insurance claims completed by the involved road users. An analysis of survey variables was compared to a case analysis including word data derived from the same survey and filed insurance claims documents. For each accident, the added value of having access to more than one source of information was assessed. To limit the scope of this study, three particular topics were investigated: available information on low vigilance (e.g., being drowsy, ill); secondary task distraction (e.g., talking with passengers, mobile phone use); and distraction related to the driving task (e.g., looking for approaching vehicles). Results suggest that for low vigilance and secondary task distraction, a combination of the mail survey and insurance claims documents provide more reliable and detailed pre-crash information than survey variables alone. However, driving related distraction appears to be more difficult to capture. In order to gain a better understanding of the above issues and how frequently they occur in accidents, the data sources and analysis methods suggested here may be combined with other investigation methods such as in-depth accident investigations and pre-crash data recordings. 相似文献