170,093 research outputs found
Wave propagation in cellular locally resonant metamaterials
No full textAbstract Locally resonant acoustic metamaterials have recently attracted a great interest due to their dynamic behaviour, characterized by a band gap at relatively low frequencies. This paper provides a numerical study, by means of finite element modal analyses, of the dynamic properties of 1D mass-in-mass and 2D cellular locally resonant metamaterials. The 2D metamaterial is constituted by a cellular metallic lattice, filled by a soft light material with heavy inclusions or resonators. The influence of material parameters and cell geometry on the band gap width and frequency level are explored. In addition to the usual square lattice we also consider a hexagonal one, which proves to be more efficient for wave filtering.</div
Bending-Dominated Auxetic Materials for Wearable Protective Devices Against Impact
No full textAuxetic metamaterials have high energy absorption capacity and indentation resistance, due to their significant densification mechanism during compression. This study investigates the performance of structured materials in layered thin plates, with potential applications in wearable protective devices for sport activities. Two different 3D lattices, conventional and re-entrant honeycomb, are studied in detail and their dynamic behaviour is compared with that of a 2D auxetic lattice. Initially, the equivalent elastic properties of the proposed geometries are investigated at varying equivalent densities. Then a new lightweight solution of a sandwich structure with an auxetic metamaterial core is proposed for possible application to facial protective masks. Numerical impact analyses of the problem show the potential benefit of the present proposal with respect to traditional mask geometries
Big constraints to small firms'growth ? business environment and employment growth across firms
No full textUsing data on more than 56,000 enterprises in 90 countries, this paper finds that objective conditions in the business environment vary substantially across firms of different sizes and that there are important non-linearities in their impact on employment growth. The paper focuses on four areas: access to finance, business regulations, corruption, and infrastructure. The results, particularly on the impacts of finance and corruption on growth, depend on whether and how the analysis accounts for the possible endogeneity of the business environment. Controlling for endogeneity revises the finding that small firms benefit most from access to finance, particularly for sources of finance associated with investment and growth. The findings are also sensitive to how “small” is defined. Differentiating micro (less than 10 employees) from other small firms shows that, while small firms can be disadvantaged in such an environment, micro firms tend to be proportionally less affected by a weak business climate – and, on occasion, it can help them to grow. Overall, allowing different size classifications provides insights into the impact of the business environment that are lost in more aggregate analyses.Microfinance,Private Participation in Infrastructure,Small Scale Enterprise,Access to Finance,Labor Policies
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
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
Dispelling 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
Comparing Apples with....Apples : how to make (more) sense of subjective rankings of constraints to business
No full textThe use of expert or qualitative surveys to rank countries’ business investment conditions is widespread. However, within the economic literature there are concerns about measurement error and endogeneity based on characteristics of the respondents, raising questions about how well the data reflect the underlying reality they are trying to measure. This paper examines these concerns using data from 79,000 firms in 105 countries. The findings show that first, qualitative rankings correlate well with quantitative measures of the business environment, using both quantitative measures from within the survey and from external sources. Second, there are systematic variations in perceptions based on firm characteristics - focusing in particular on size and growth performance. However, it is not that an optimistic view of the business environment is simply the expression of a firm’s own performance. Rather, firm size and performance affect the relative importance of certain constraints, particularly in areas such as finance, time with officials/inspectors, corruption, and access to reliable electricity. The results also show that much of the variation in subjective responses by firm types is largely due to differences in the objective conditions across firm types. There is little evidence that size and performance have non-linear effects in how constraining a given objective condition is reported to be. Overall, concerns about endogeneity remain in using business environment indicators to explain firm performance, but this stems primarily from the fact that who you are and how well you are doing can affect the conditions you face rather than whether the indicator used is qualitative or quantitative.Microfinance,E-Business,Transport Economics Policy&Planning,Debt Markets,Access to Finance
Academic Officers, C. 1990s 3530
No full textAcademic Officers/Bill Darby, Ralph Garzia, Blanche Touhill, Joan Rapp, Betty Van Uum, Shirley Martin, Roosevelt Wright, Joel Glassman, Charley Schmitz, Everette Nance, Jim Doyle, Bob Nauss, Doug Wartzok, Don Mertz, Terry Jones, Tom Mcphail, Wendell Smith, Don Driemeier, C. 1990s 3530https://irl.umsl.edu/photo/4530/thumbnail.jp
sj-pdf-1-vet-10.1177_03009858231158075 – Supplemental material for Ophthalmic and immunopathological characterization of systemic infectious diseases in cats
No full textSupplemental material, sj-pdf-1-vet-10.1177_03009858231158075 for Ophthalmic and immunopathological characterization of systemic infectious diseases in cats by Júlia G. Wronski, Bianca S. de Cecco, Jacqueline Raiter, Luan C. Henker, Cíntia de Lorenzo, Marcele B. Bandinelli, David Driemeier, Saulo P. Pavarini and Luciana Sonne in Veterinary Pathology</p
- …
