1,721,017 research outputs found
‘Biological’ revolution and strategies for innovation in pharmaceutical companies
No full textFundamental advances in the life sciences are exerting a profound influence on the structure of the pharmaceutical industry and the strategies of drug companies. The ‘biological’ revolution makes it possible to apply a scientific method to drug research. This paper argues that pharmaceutical companies can take advantage of the new method only if they encourage ‘openness’ of their research. We also offer a framework to explain why innovations in this industry increasingly result from networks of agents with complementary skills and resources. Greater use of scientific knowledge implies that important information for innovation can be expressed in relatively general and universal forms. This eases information exchange, and encourages specialisation and division of labour in drug R&D and marketing. Finally, the possibility of a division of labour in innovation opens new opportunities for medium‐sized national pharmaceutical firms in Europe. Provided that they found their strategies on high‐quality research in specialised niches, they can set up alliances with partners that possess complementary knowledge, and supply resources for clinical development and international marketing. Copyright © 1993, Wiley Blackwell. All rights reserve
Polarisation dynamics of a birefringent Fabry-Perot cavity
No full textOptical Fabry–Perot cavities always show a non-degeneracy of two orthogonal polarisation states. This is due to the unavoidable birefringence of dielectric mirrors whose effects are extremely important in Fabry–Perot-based high-accuracy polarimeters: in birefringent cavities, ellipticities and rotations mix. We have developed and present here a theory of the polarisation state dynamics in a birefringent Fabry–Perot resonator, and we validate it through measurements performed with the polarimeter of the PVLAS experiment. The measurements are performed while a laser is frequency-locked to the cavity, and provide values for the phase difference between the two orthogonal polarisation components introduced by the combination of the two cavity mirrors (equivalent wave-plate) and for the finesse of the cavity. The theoretical formulas and the experimental data agree well showing that the consequences of the mirror birefringence must be taken into account in this and in any other similar experiment
Optical Polarimetry for Fundamental Physics
Full text linkSensitive magneto-optical polarimetry was proposed by E. Iacopini and E. Zavattini in 1979 to detect vacuum electrodynamic non-linearity, in particular Vacuum Magnetic Birefringence (VMB). This process is predicted in QED via the fluctuation of electron–positron virtual pairs but can also be due to hypothetical Axion-Like Particles (ALPs) and/or MilliCharged Particles (MCP). Today ALPs are considered a strong candidate for Dark Matter. Starting in 1992 the PVLAS collaboration, financed by INFN, Italy, attempted to measure VMB conceptually following the original 1979 scheme based on an optical cavity permeated by a time-dependent magnetic field and heterodyne detection. Two setups followed differing basically in the magnet: the first using a rotating superconducting 5.5 T dipole magnet at the Laboratori Nazionali di Legnaro, Legnaro, Italy and the second using two rotating permanent 2.5 T dipole magnets at the INFN section of Ferrara. At present PVLAS is the experiment which has set the best limit in VMB reaching a noise floor within a factor 7 of the predicted QED signal: Δn(QED)=2.5×10−23 @ 2.5 T. It was also shown that the noise floor was due to the optical cavity and a larger magnet is the only solution to increase the signal to noise ratio. The PVLAS experiment ended at the end of 2018. A new effort, VMB@CERN, which plans to use a spare LHC dipole magnet at CERN with a new modified optical scheme, is now being proposed. In this review, a detailed description of the PVLAS effort and the comprehension of its limits leading to a new proposal will be given
Cotton-Mouton effect of molecular oxygen: A novel measurement
No full textA novel apparatus to measure small magnetic birefringences is described. It is based on a high-finesse Fabry-Perot cavity, to which a Nd:YAG laser is frequency locked, and on a 1.1-T permanent dipole magnet. We report the new measurement of the magnetic anisotropy of the refraction index (Cotton-Mouton effect) for molecular oxygen at λ= 1064 nm, T = 20°C. Our result, Δn(O2) = (-2.29 ± 0.08)10-12(B/1 T)2(P/1 atm), is consistent with the existing theoretical predictions and falls in line with the previous experimental results taken at different wavelengths. © 1998 Optical Society of America
The PVLAS experiment: A 25 year effort to measure vacuum magnetic birefringence
Full text linkThis paper describes the 25 year effort to measure vacuum magnetic birefringence and dichroism with the PVLAS experiment. The experiment went through two main phases: the first using a rotating superconducting magnet and the second using two rotating permanent magnets. The experiment was not able to reach the predicted value from QED. Nonetheless the experiment has set the current best limits on vacuum magnetic birefringence and dichroism for a field of Bext=2.5 T, namely, Δn(PVLAS)=(12±17)×10−23 and |Δκ|(PVLAS)=(10±28)×10−23. The uncertainty on Δn(PVLAS) is about a factor 7 above the predicted value of Δn(QED)=2.5×10−23 @ 2.5 T
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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