133,015 research outputs found
Dynamics of High-Technology Firms in the Silicon Valley
No full textThe pace of technological innovation since World War II is dramatically accelerating following the commercial exploitation of the Internet. Since the mid 90’s fiber optics capacity (infrastructure for transmission of information including voice and data) has incremented over one hundred times thanks to a new technology, dense wave division multiplexing, and Internet traffic has increased over 1.000 times. The dramatic advances in information technology provide excellent examples of the critical relevance of the knowledge in the development of competitive advantages. The Silicon Valley (SV) that about fifty years ago was an agricultural region became the center of dramatic technological and organizational transformations. In fact, most of the present high-tech companies did not exist twenty years ago. Venture capital contribution to the local economy is quite important not only due to the magnitude of the financial investment (venture investment in SV during 2000 surpassed 25.000 millions of dollars) but also because the extent and quality of networks (management teams, senior employees, customers, providers, etc.) that bring to emerging companies. How do new technologies develop? What is the role of private and public investment in the financing of R&D? Which are the most dynamical agents and how do they interact? How are new companies created and how do they evolve? The discussion of these questions is the focus of the current work.Technological development, R&D, networks
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Atomic scale mechanism for the Ge-induced stabilization of the tetragonal, very high k, phase of ZrO2
No full textUsing x-ray absorption fine structure aided by ab initio structural simulations we demonstrate the
atomic scale mechanism responsible for the stabilization of the otherwise unstable and very high-j
tetragonal phase of ZrO2 by the incorporation of Ge atoms. In tetragonal ZrO2 the cation has a split
first coordination shell formed by eight oxygen atoms. We provide a direct experimental proof
that when Ge is incorporated in the oxide, four of the eight O atoms collapse towards Ge giving
rise to a local structure strongly reminiscent of that found in quartz-like GeO2, thus stabilizing the
tetragonal phase
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Corso Laboratorio 2 per il Progetto Lauree Scientifiche: "Elettroni e Fotoni dagli Atomi ai Solidi"
No full textLo studio del comportamento di elettroni e fotoni nei semiconduttori, e della loro interazione, costituisce la base per la comprensione dei fenomeni ottici ed elettrici in semiconduttori. L’interazione radiazione-materia e le proprietà ottiche ed elettroniche dei semiconduttori sono alla base dello sviluppo dei moderni dispositivi optoelettronici a semiconduttore.
Gli argomenti trattati durante il corso verteranno su: modello dei livelli energetici dell'atomo, effetto fotoelettrico da livelli profondi, fluorescenza,interazione radiazione materia, proprietà elettriche e ottiche dei solidi. Alcune applicazioni: dispositivi optoelettronici (celle solari fotovoltaiche, LED, LASER).
Gli studenti “osserveranno” i livello energetici degli atomi ed eseguiranno misure sperimentali della resistività elettrica e del coefficiente di assorbimento ottico in semiconduttori
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Do ”green” products really command a premium price? Evidence from the Italian home appliances market
No full textNew Opportunities to Study Defects by Soft X-Ray Absorption Fine Structure
No full textX-ray absorption fine structure can determine the local structure of most atoms in the periodic table. The great recent improvements in the performance of synchrotron radiation sources and techniques and advances in the simulations of the spectra have opened new opportunities, especially in the study of dilute systems in the soft X-ray range. In this contribution we will show some recent results that demonstrate how semiconductor physics may greatly benefit from such progress. In fact, doping or alloying of semiconductors with light elements, that have K absorption edges in the soft X-ray range, is widely employed to tune semiconductor properties. X-ray absorption fine structure investigations on such systems can give an important contribution towards the understanding and optimization of technological processes
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