169,893 research outputs found
Reagan’s innovation dividend? Technological impacts of the 1980s US defense build-up
No full textUS government spending since World War II has been characterized by large
investments in defense related goods, services and R&D. In turn, this means that the
Department of Defense (DoD) has had a large role in funding corporate innovation in the
US. This paper looks at the impact of military procurement spending on corporate
innovation among publicly traded firms for the period 1966-2003. The study utilizes a
major database of detailed, historical procurement contracts for all Department of
Defense (DoD) prime contracts since 1966. Product-level spending shifts – chiefly
centered around the Reagan defense build-up of the 1980s – are used as a source of
exogenous variation in firm-level procurement receipts. Estimates indicate that defense
procurement has a positive absolute impact on patenting and R&D investment, with an
elasticity of approximately 0.07 across both measures of innovation. In terms of
magnitudes, the contribution of defense procurement to innovation peaked during the
early Reagan build-up, accounting for 11.4% of the total change in patenting intensity
and 6.5% for R&D. This compares to a defense sector share in output of around 4%. The
later defense cutbacks under Bush Senior and Clinton then curbed the growth in
technological intensity by around 2%
Methanol adsorption on Si(111)-(7x7), investigated by core-line photoemission and mass spectrometry of photodesorbed ions
No full textDeuterated methanol adsorption on Si(111)-(7 x 7) has been studied by C Is and O Is core-line synchrotron radiation photoemission and mass spectrometry of photodesorbed ions. Experiments were performed as a function of coverage and temperature. Two different C Is photoemission peaks hint at two different adsorbed species, the first one related to the methoxy fragment produced after dissociative adsorption, the second one is attributed to a CD, species. Both peaks disappear after heating at 350 degrees C, though the methoxy species is more reactive, and a third peak appears. The nature of the species producing the third peak was deduced by means of the mass spectra after heating the sample at 400 degrees C and attributed to C dispersed on the silicon surface
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
Initial stage of NO adsorption on Si(100)-(2 x 1) studied by synchrotron radiation photoemission and photodesorption
No full textThe NO adsorption on the Si(100)-(2 x 1) surface was investigated by synchrotron radiation photoemission and photodesorption in the energy ranges including the valence band and the Si 2p, N 1s and O 1s core levels. The study was performed both ass function of NO exposure and as a function of temperature in the range 20-300 K. The photoemission experiments show clear evidence of a dissociative adsorption process both at room temperature as well as at temperatures as low as 20 K. Furthermore, the silicon surface states are involved in the adsorption process. The core level spectroscopy shows a complex adsorption pattern of the atomic species, which might involve a sub-surface migration of nitrogen atoms. The photodesorption yields only O+ in the Si 2p and O Is energy ranges. No nitrogen ion desorption is detected. In the Si 2p energy range the O+ photodesorption pattern follows the enhanced secondary electron yield when crossing the ionization threshold. In the O Is energy range the O+ photodesorption pattern is interpreted in terms of a partial sub-surface migration of oxygen atoms. (C) 2000 Elsevier Science B.V. All rights reserved
Different role of filled and empty surface states in a polyfunctional molecule adsorption: Geranyl acetone on Si(111)7x7
No full textNew perspectives in molecular electronics are opening up through controlled surface molecular synthesis. The first step of such a synthesis implies the adsorption of a polyfunctional molecule, which might use one functional group for the surface adsorption, and the other one(s) for further reactions. Here we present an adsorption study of Si(111)7x7 of geranyl-acetone (C13H22O, E-5,9 undecadien-one) characterized by a ketone and two unconjugated double bonds. The study has been performed by temperature and coverage dependent valence band photoemission and room temperature scanning tunneling microscopy. The use of these combined techniques allows us to infer that the interaction between the geranyl acetone and the silicon surface occurs selectively through the rest atom and the carbonyl group, most likely through the oxygen atom. The geranyl acetone does not undergo any fragmentation upon adsorption Si(111)7x7, as has been observed for smaller molecules on the same surface {acetaldehyde [Y. Bu, J. Breslin, M. C. Lin, J. Phys. Chem. B 101, 1872 (1997)] for instance}. The interaction of the chain with the surface is weak and is characterized in the STM images as a darkening of one adatom in positive bias, around the reacted rest atom. (C) 2002 American Institute of Physics
Études régionales : Mégare. G. Despinis, Μεγαρικά (= Megarika) Nills Hellner, Η «κρήνη του Θεαγένους» στα Μέγαρα. Ιστορία και αρχιτεκτονική ενός μνημείου του 5ου αι. π. Χ. (= La «fontaine de Théagène» à Mégara. Histoire et architecture d’un monument du 5e s. av. J.-C.)
No full textDoukellis Panagiotis N. Études régionales : Mégare. G. Despinis, Μεγαρικά (= Megarika) Nills Hellner, Η «κρήνη του Θεαγένους» στα Μέγαρα. Ιστορία και αρχιτεκτονική ενός μνημείου του 5ου αι. π. Χ. (= La «fontaine de Théagène» à Mégara. Histoire et architecture d’un monument du 5e s. av. J.-C.). In: Dialogues d'histoire ancienne, vol. 37, n°2, 2011. p. 250
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Photon-stimulated desorption of methanol on Si(111)7 x 7 and Si(100)2 x 1 at the C 1s and O 1s thresholds
No full textDispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Synchrotron radiation photoemission and photostimulated desorption of deuterated methanol on Si(111)7 × 7 and Si(100)2 × 1
No full textDeuterated methanol adsorption on Si(111)7 × 7 and Si(100)2 × 1 surfaces has been investigated, at room temperature, by synchrotron radiation photoemission and photostimulated desorption. Photoemission experiments as a function of methanol coverage show that deuterated methanol adsorption is dissociative on both surfaces and occurs via σO-D bond breakage and σSi-O bond formation. Site selectivity is displayed by the methoxy species on Si(111)7 × 7 surface, since the S2 surface state related to the rest atoms is quickly quenched upon low coverage adsorption. The S1 surface state is quenched only subsequently at much higher coverages. The photostimulated desorption pattern is similar for the two surfaces and strongly depends on the investigated energy range. D+ is always the most abundant ion produced, but higher mass fragments are present too in the energy range including the C Is threshold, where multiple desorption processes are possibly taking place
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