共查询到20条相似文献，搜索用时 31 毫秒
1.
Elias Burstein 《Journal of The Franklin Institute》2011,348(3):489-499
The Benjamin Franklin Medal for Physics is awarded to Dr. Deborah Jin (JILA, NIST and the University of Colorado) “in recognition of her pioneering investigations into the quantum properties of an ultra-cold gas of fermionic atoms and, in particular, for her creation of the first degenerate Fermi gas of atoms”. 相似文献
2.
This study explores the role of contemporaneous peer effects in driving an academic's involvement with industry. Specifically, we examine the influence of workplace peers and personal collaborators and how these effects are moderated by the career age of the scientist. Moreover, we look at situations in which both types of social influence are incongruent and the academic is faced with “dissonance”. Based on survey data of 355 German academics in the field of biotechnology and publication data from the Science Citation Index Expanded (SCIE), we find that the scientist's involvement with industry increases with the orientation of the scientist's department toward industry (“localized peer effect”). This effect turns out to be moderated by the scientist's age, such that the localized peer effect decreases with age and finally turns negative for very senior scientists. Moreover, we find that a scientist's involvement increases with the industry orientation of the scientist's co-authors (“personal peer effect”), irrespective of the scientist's age. In case both types of social influence are incongruent, younger scientists will revert to localized norms while more experienced scientists will orient themselves more toward their personal collaborators. 相似文献
3.
“Scientific and technical human capital” (S&T human capital) has been defined as the sum of researchers’ professional network ties and their technical skills and resources [Int. J. Technol. Manage. 22 (7-8) (2001) 636]. Our study focuses on one particular means by which scientists acquire and deploy S&T human capital, research collaboration. We examine data from 451 scientists and engineers at academic research centers in the United States. The chief focus is on scientists’ collaboration choices and strategies. Since we are particularly interested in S&T human capital, we pay special attention to strategies that involve mentoring graduate students and junior faculty and to collaborating with women. We also examine collaboration “cosmopolitanism,” the extent to which scientists collaborate with those around them (one’s research group, one’s university) as opposed to those more distant in geography or institutional setting (other universities, researchers in industry, researchers in other nations). Our findings indicate that those who pursue a “mentor” collaboration strategy are likely to be tenured; to collaborate with women; and to have a favorable view about industry and research on industrial applications. Regarding the number of reported collaborators, those who have larger grants have more collaborators. With respect to the percentage of female collaborators, we found, not surprisingly, that female scientists have a somewhat higher percentage (36%) of female collaborators, than males have (24%). There are great differences, however, according to rank, with non-tenure track females having 84% of their collaborations with females. Regarding collaboration cosmopolitanism, we find that most researchers are not particularly cosmopolitan in their selection of collaborators—they tend to work with the people in their own work group. More cosmopolitan collaborators tend have large grants. A major policy implication is that there is great variance in the extent to which collaborations seem to enhance or generate S&T human capital. Not all collaborations are equal with respect to their “public goods” implications. 相似文献
4.
Do men and women academic faculty vary in their research collaboration patterns and strategies? This straightforward question does not lend itself to a straightforward answer. A great many sex-correlated variables could possibly mitigate the relationship of sex and collaboration. If one finds sex-correlated differences in the number of collaborators, can one infer that there is something intrinsic to men's and women's work strategies and preferences? Or would such differences owe instead to women's and men's different positions in work structures and hierarchies? The focus here is on two sets of research collaboration variables, numbers of collaborators and the collaboration strategies employed. The study uses questionnaire data from the U.S. National Survey of Academic Scientists (n = 1714) and tests several hypotheses about collaboration numbers and strategies. Regression results indicate, counter to the core hypotheses and almost all published literature, that in a properly specified model, one taking into account such factors as tenure, discipline, family status and doctoral cohort, women actually have somewhat more collaborators on average than do men. For both men and women, those with more industrial interactions and those affiliated with university research centers have more collaborators. Men and women differ in their collaborator choice strategies. Men are more likely to be oriented to “instrumental,” and “experience” strategies, while both men and women are motivated by “mentoring” strategies. Regression analyses show that for both men and women, having a coherent collaborator choice strategy predicts the number of collaborators. 相似文献
5.
Taleb H. Ibrahim 《Journal of The Franklin Institute》2010,347(5):875-881
Recently molecular modeling was employed on the metal-extracted aggregates that form during the liquid/liquid extraction of transition metals. During the extraction process, the aqueous phase pH is adjusted with sodium hydroxide. In additional to the formation of the transition metal-extractant reversed micelles, sodium-bis(2-ethylhexyl) phosphate (NaDEHP) reversed micelles can also form. According to the classical model of reversed micelles, water molecules act as promoters for the formation of reversed micelles. Water molecules act as “gluing” agents for micellization in apolar media. Here we report a unique finding about the role of water molecules in reversed micellar aggregates using molecular modeling. The molecular modeling of the reversed micellar system of NaDEHP in n-heptane clearly shows that water molecules can act as an “antimicellization” agent. Water molecules have no gluing effect on the formation of NaDEHP reversed micelles. In fact, large NaDEHP reversed micelles are formed in “dry” conditions. 相似文献
6.
Hao Gao Cong Liu Andreas Hermann Richard J Needs Chris J Pickard Hui-Tian Wang Dingyu Xing Jian Sun 《国家科学评论(英文版)》2020,7(10):1540
Helium and methane are major components of giant icy planets and are abundant in the universe. However, helium is the most inert element in the periodic table and methane is one of the most hydrophobic molecules, thus whether they can react with each other is of fundamental importance. Here, our crystal structure searches and first-principles calculations predict that a He3CH4 compound is stable over a wide range of pressures from 55 to 155 GPa and a HeCH4 compound becomes stable around 105 GPa. As nice examples of pure van der Waals crystals, the insertion of helium atoms changes the original packing of pure methane molecules and also largely hinders the polymerization of methane at higher pressures. After analyzing the diffusive properties during the melting of He3CH4 at high pressure and high temperature, in addition to a plastic methane phase, we have discovered an unusual phase which exhibits coexistence of diffusive helium and plastic methane. In addition, the range of the diffusive behavior within the helium-methane phase diagram is found to be much narrower compared to that of previously predicted helium-water compounds. This may be due to the weaker van der Waals interactions between methane molecules compared to those in helium-water compounds, and that the helium-methane compound melts more easily. 相似文献
7.
Roger A. Grey Author Vitae 《Journal of The Franklin Institute》2004,341(3):197-205
Throughout his distinguished career of over 40 years, Robin Hochstrasser has made significant contributions to several areas of science in the fields of chemical and biochemical physics. He has been at the forefront and made fundamental contributions to the fields of photochemistry, solid-state chemistry, ultra-fast laser spectroscopies, and protein dynamics. He has been a prolific researcher, producing over 560 publications. His work has been characterized by experts in the fields as “a constant stream of experiments of lasting significance” (J. Phys. Chem. 100 (1996) 11791).Robin began his career in the 1960s using a variety of magnetic and electric field measurements to study crystals at low temperatures to understand spin quantization in solids and electron exchanged-mediated energy transfer. This work, described as a “classic contribution” (J. Phys. Chem. 100 (1996) 11791) was the basis for much of the subsequent experimental and theoretical work on the effect of magnetic fields on molecular spectra and on the measurements of dipole moments.In the late 1970s, Robin recognized the power of laser technology for the study of molecules and soon became a leader in the field investigating solid, gas phase, and condensed phase systems. He developed and applied various ultra-fast laser techniques to study the structure and dynamics of complex molecules in liquid phase, chemical, and biochemical reactions. He made seminal contributions to the development of two-dimensional infrared spectroscopy (2D IR) on a time scale of a picosecond or less. This 2D IR spectroscopy measures coupling between two functional groups in a large molecule and can thus be used to measure distances, as for example, two amide carbonyl groups in a peptide molecule. On the ultra-fast timescale, one application of 2D IR is to gain information on the rate of protein folding and unfolding in solution. Some of Robin's greatest contributions to understanding biomolecules are said to be in the experimental studies on the picosecond and femtosecond dynamics of heme proteins. Using techniques he developed he was able to observe the interactions of oxygen, carbon monoxide, and nitric oxide with hemoglobin inside the protein. 相似文献
8.
In this study, a microfluidic process is proposed for preparing monodisperse micrometer-sized hydrogel beads. This process utilizes non-equilibrium aqueous droplets formed in a polar organic solvent. The water-in-oil droplets of the hydrogel precursor rapidly shrunk owing to the dissolution of water molecules into the continuous phase. The shrunken and condensed droplets were then gelled, resulting in the formation of hydrogel microbeads with sizes significantly smaller than the initial droplet size. This study employed methyl acetate as the polar organic solvent, which can dissolve water at 8%. Two types of monodisperse hydrogel beads—Ca-alginate and chitosan—with sizes of 6–10 μm (coefficient of variation < 6%) were successfully produced. In addition, we obtained hydrogel beads with non-spherical morphologies by controlling the degree of droplet shrinkage at the time of gelation and by adjusting the concentration of the gelation agent. Furthermore, the encapsulation and concentration of DNA molecules within the hydrogel beads were demonstrated. The process presented in this study has great potential to produce small and highly concentrated hydrogel beads that are difficult to obtain by using conventional microfluidic processes. 相似文献
9.
10.
This study uses bibliometric analysis and citation context analysis to identify the influence of the main concepts embedded in Taylor’s 1968 classic article entitled Question-Negotiation and Information-Seeking in Libraries. This study analyses articles published between 1969 and 2010 which cite Taylor’s article. The results show that Taylor’s article on a question-negotiation model is increasingly visible and its influence is not limited to the discipline of library and information science. Of the 14 cited concepts identified, the concept of “four levels of information needs” was cited most (31.7%), followed by “question negotiation” (20.5%) and “other concepts relating to information needs” (17.9%). The results indicate an increasing trend in the citations of “four levels of information needs” and this concept also received the most attention from information retrieval research. A decreasing trend was evident for the concept of “question negotiation” and this concept was frequently cited by reference service researchers. In addition, among the 10 citation functions, “related literature” was dominant (30.8%). Both “evidence” and “views” were in second place with the same percentage (18.7%), followed by “terms” (9.2%) and “background information” (7.2%). A decreasing trend was identified in the top three citation functions, whereas an increasing trend was observed in the “term” and “background information” functions. 相似文献
11.
Raphael Kaplinsky 《Research Policy》2011,40(2):193-203
Innovation and technological change play an important role in poverty reduction through their contribution to growth, their use of factors of production, their environmental spillovers, the social relations associated with production and the characteristics of the products which they produce. It was only after the 1960s that these linkages were identified, with the recognition that much of global technological progress was directed to meet the needs of the global rich, and was best-suited to operation in high-income environments. The development and diffusion of “appropriate technologies” was an agenda largely pursued by the not-for-profit Appropriate Technology movement. However, with the global diffusion of innovative capabilities, and the rapid rise of incomes of the very poor - the “second bottom billion” - innovation for the poor and innovation appropriate for production in low-wage and poor-infrastructure environments has increasingly become an arena for profitable production. The very large size of China and India, coupled with their growing technological capabilities and the rapid growth of low-incomes, makes it likely that they will become the dominant sources of innovation for the poor. 相似文献
12.
Despite the common public use of Web search engines, their internal design details mostly remain as a black art. The speculation is that there is a significant knowledge gap between what is published by academia and what is guarded behind the doors of large-scale search companies. “Search Engines: Information Retrieval in Practice” is one of the few books that make an attempt to cover issues involved in search engine design and is probably the most comprehensive book published so far on this topic. Unfortunately, the book fails to be a complete search engine guide as its content is dominated by the topics from information retrieval, text processing, and statistics. More precisely, the focus of the book is biased towards the “search” rather than the “engines” as, in most places, discussions on effectiveness dominate those on efficiency by a great margin. However, the book stands as a very solid IR book. 相似文献
13.
Mauro Lombardi 《Research Policy》2003,32(8):1443-1462
The aim of this paper is to propose an explanation of the changes of dynamic matching between systemic properties of local production systems (LPS) and characteristics of the competitive environment. An evolutionary sequence travelled during the last three decades by Italian LPS is identified and an explanation of long-term dynamics is based on how information flows and knowledge are structured within a local environment. The “traditional” pattern of interlocking behaviours of different agents is defined as cognitive architecture, which evolutionarily emerges as invisible mind. Evolutionary pressures lead new patterns of relationships and interlocking behaviours, which we define as a tendency for more visible “minds” to assert themselves. 相似文献
14.
Despite a number of studies looking at Web experience and Web searching tactics and behaviours, the specific relationships between experience and cognitive search strategies have not been widely researched. This study investigates how the cognitive search strategies of 80 participants might vary with Web experience as they engaged in two researcher-defined tasks and two participant-defined information seeking tasks. Each of the two researcher-defined tasks and participant-defined tasks included a directed search task and a general-purpose browsing task. While there were almost no significant performance differences between experience levels on any of the four tasks, there were significant differences in the use of cognitive search strategies. Participants with higher levels of Web experience were more likely to use “Parallel player”, “Parallel hub-and-spoke”, “Known address search domain” and “Known address” strategies, whereas participants with lower levels of Web experience were more likely to use “Virtual tourist”, “Link-dependent”, “To-the-point”, “Sequential player”, “Search engine narrowing”, and “Broad first” strategies. The patterns of use and differences between researcher-defined and participant-defined tasks and between directed search tasks and general-purpose browsing tasks are also discussed, although the distribution of search strategies by Web experience were not statistically significant for each individual task. 相似文献
15.
Richard R. Nelson 《Research Policy》2008,37(1):1-11
In recent years “institutions” have again become a central focus of economists and other scholars studying the processes of economic growth, and the reasons why nations have differed so greatly in their achievements on this front. However, with few exceptions the exploration of the role of institutions has not been connected with a coherent analysis of the relationships between institutions and institutional change and technological advance. This paper proposes a way of analyzing these relationships. The concept of “social technologies” which support “physical technologies” plays a key role in the analysis. 相似文献
16.
A user study of aNobii was conducted with an aim to exploring possible criteria for evaluating social navigational tools. A set of measures designed to capture various aspects of the benefits provided by the tools was proposed. To test the applicability of these measures, a within-subject experimental design was adopted where fifty regular aNobii users searched alternately with three book-finding tools: browsing “friends’ bookshelves”, “similar bookshelves”, and “books by known authors”. Other than the self-report user experience and search result measures, the “choice set” model was used as a novel framework for navigational effectiveness. Further analyses were conducted to explore whether three aspects of reader preference, “preference insight”, “preference diversity”, and “reading involvement” might influence the performance of the tools. 相似文献
17.
This study examines how libraries within college and university settings in the United States have dealt with the influx of patron mobile telephone use. We contacted 150 colleges and universities throughout the United States and received 87 responses. These institutions were ranked by US News and World Report in their 2006 Edition of “America’s Best Colleges;” we sampled from their list stratified within the following categories: “top public universities;” “best liberal arts colleges;” “fourth tier liberal arts colleges;” “best national universities;” and “fourth tier national universities.” We found that those college and university libraries adopt an array of stances when approaching cell phone use within their library facilities. These approaches include structured guidelines that specifically address cell phone use posted on the library website, signs displayed throughout the library barring cell phone use, and signage that provides patrons with a list of areas in which use is permitted. Interestingly, we found that several libraries lack any kind of mobile phone policy and instead, assume all patrons will behave in a proper way. 相似文献
18.
Roger A. Grey Author Vitae 《Journal of The Franklin Institute》2006,343(3):214-222
The scientific theme for the 2005 Bower Award was Chemistry, specifically the field of Catalysis. The Franklin Institute, Philadelphia, Pennsylvania, awarded the 2005 Bower Award and Prize for achievement in Science to Henri B. Kagan for his seminal discovery of fundamental chemical principles that explain the impact of catalyst shape on its effectiveness in controlling chemical reactions, thus greatly simplifying the manufacture of pharmaceutically important compounds. Henri Kagan is widely recognized as a pioneer in the field of asymmetric catalysis. Starting in the early 1970s, his reports of the synthesis of the chiral bidentate diphosphine ligand and the demonstration of its use with soluble rhodium compounds to catalyze the efficient production of large enantiomeric excesses of chiral molecules in asymmetric hydrogenations has had far reaching effects on research in the field asymmetric catalysis. The concept of using chiral bidentate ligands of C2 symmetry has led the way for numerous developments in asymmetric catalysis. Later in 1986 his introduction of the concept and investigations into “nonlinear effects in asymmetric synthesis” using catalysts with chiral ligands that were not optically pure challenged the widely accepted assumption that the enantiomeric excess which is possible correlates linearly with the optical purity of the chiral ligands. He reported the first example in asymmetric catalysis where the optical purity of the product significantly exceeded the optical purity of the chiral ligand. 相似文献
19.
Zhichao Guan Yuan Zou Mingxia Zhang Jiangquan Lv Huali Shen Pengyuan Yang Huimin Zhang Zhi Zhu Chaoyong James Yang 《Biomicrofluidics》2014,8(1)
Although digital detection of nucleic acids has been achieved by amplification of single templates in uniform microfluidic droplets and widely used for genetic analysis, droplet-based digital detection of proteins has rarely been reported, largely due to the lack of an efficient target amplification method for protein in droplets. Here, we report a key step towards digital detection of proteins using a highly parallel microfluidic droplet approach for single enzyme molecule detection in picoliter droplets via enzyme catalyzed signal amplification. An integrated microfluidic chip was designed for high throughput uniform droplet generation, monolayer droplet collection, incubation, detection, and release. Single β-galatosidase (β-Gal) molecules and the fluorogenic substrate fluorescein di-β-D-galactopyranoside were injected from two separated inlets to form uniform 20 μm droplets in fluorinated oil at a frequency of 6.6 kHz. About 200 000 droplets were captured as a monolayer in a capture well on-chip for subsequent imaging detection. A series of β-Gal solutions at different concentrations were analyzed at the single-molecule level. With no enzyme present, no droplets were found to fluoresce, while brightly fluorescent droplets were observed under single-enzyme molecule conditions. Droplet fluorescence intensity distribution analysis showed that the distribution of enzyme molecules under single-molecule conditions matched well with theoretical prediction, further proving the feasibility of detecting single enzyme molecules in emulsion droplets. Moreover, the population of fluorescent droplets increased as the β-Gal concentration increased. Based on a digital counting method, the measured concentrations of the enzyme were found to match well with input enzyme concentration, establishing the accuracy of the digital detection method for the quantification of β-Gal enzyme molecules. The capability of highly parallel detection of single enzyme molecules in uniform picoliter droplets paves the way to microdroplet based digital detection of proteins. 相似文献
20.
Sampsa Hyysalo 《Research Policy》2009,38(5):726-735
Failure to meet the preferences and needs of users has been consistently stressed as a major cause of unsuccessful R&D for over 30 years. Yet little seems to change. An important element in this “producer-user paradox” is a lack of frameworks able to inform empirical research and the work that people do when they bridge designing, implementing, using and managing new technology. “Learning economy” and “social learning in technological innovation” appear promising as such integrative frameworks not least due to their emphasis on learning between producers and users. The present paper examines the value in the way learning is treated in these frameworks for empirical research and for the practitioners, and to this aim contrasts these frameworks to findings from a line of studies on learning between producers and users of new health technologies. 相似文献