16,943 research outputs found
A functional view on prototypes
No full textThe human mind may produce prototypization within virtually any realm of cognition and behavior. A "comparative prototype-typology" might prove to be an interesting field of study – perhaps a new subfield of semiotics. This, however, would presuppose a clear view on the samenesses and differences of prototypization in these various fields. It seems realistic for the time being that the linguist first confine himself to describing prototypization within the realm of language proper. The literature on prototypes has steadily grown in the past ten years or so. I confine myself to mentioning the volume on Noun Classes and Categorization, edited by C. Craig (1986), which contains a wealth of factual information on the subject, along with some theoretical vistas. By and large, however, linguistic prototype research is still basically in a taxonomic stage - which, of course, represents the precondition for moving beyond. The procedure is largely per ostensionem, and by accumulating examples of prototypes. We still lack a comprehensive prototype theory. The following pages are intended, not to provide such, a theory, but to do the first steps in this direction. Section 2 will feature some elements of a functional theory of prototypes. They have been developed by this author within the frame of the UNITYP model of research on language universals and typology. Section 3 will bring a discussion of prototypization with regard to selected phenomena of a wide range of levels of analysis: Phonology, morphosyntax, speech acts, and the lexicon. Prototypization will finally be studied within one of the universal dimensions, that of APPREHENSION - the linguistic representation of the concepts of objects – as proposed by Seiler (1986)
Evidenzbasierte Medizin - die Bedeutung für die Evaluation von innovativen Systemen in der Chirurgie
No full textCorneal crosslinking (CXL) with 18-mW/cm irradiance and 5.4-J/cm radiant exposure-early postoperative safety.
No full textPURPOSE
To investigate safety of accelerated corneal crosslinking during the first postoperative month.
METHODS
In this retrospective study, 76 eyes of 60 patients with verified progressive keratectasia were enrolled in this study and followed for 1 month after accelerated CXL (18 mW/cm for 5 min, radiant exposure 5.4 J/cm) (A-CXL(5*18)). Preoperatively, objective refraction, slit lamp inspection, and corneal tomography were performed. Early postoperative slit lamp examinations were performed on days 1 and 4. At 1 month, objective refraction, slit lamp inspection, and corneal tomography were performed.
RESULTS
Gender distribution was m:f = 55:21, OD:OS was 40:36, and the average age was 26.5 ± 8.6 years at surgery. Only 71 of the 76 eyes completed the 1-month follow-up, indicating a dropout rate of 6.6%. In 7.0% (n = 5), sterile infiltrates were observed; 5.6% of eyes (n = 4) showed delayed epithelial healing (> 4 days) in 2.8% (n = 2); an infection occurred and in 1 eye (1.4%), a stromal scar was detected; no other complications, neither a loss of two or more Snellen lines at 1 month postoperatively, were observed. As a risk factor for sterile infiltrates, thin preoperative pachymetry could be identified (p = 0.027).
CONCLUSIONS
This study revealed no difference in early postoperative safety between CXL using 18 mW/cm and standard corneal CXL. Thinner preoperative pachymetry could be identified predicting a higher rate of postoperative sterile infiltrates
The politics and economics of regulatory impact assessment
No full textThis is the author accepted manuscript. The final version is available from the publisher via the link in this record
Phase Distribution Efficiency of cm-Scale Ultrasonically Powered Receivers
No full textIn the domain of ultrasonically powered biomedical implants, there is an increasing interest in cm-scale ultrasonic receivers (RX). However, when a single-element transducer is used as the RX transducer, an uneven phase distribution across the RX area can significantly reduce the harvestable power. In this paper, we investigate the impact of lateral and angular misalignment on the acoustic field phase distribution across the RX surface. We show that, for a single-element RX transducer, lateral misalignment has minimal effect on the harvestable power, whereas even small angular misalignments can cause a considerable reduction, especially for larger RX sizes. We present a potential solution that consists of subdividing a large RX transducer (e.g. 20 × 20mm2) into smaller elements, which significantly improves power transfer efficiency by taking advantage of the smaller phase variation across the surface of each element. The trade-offs between achieving a minimum acceptable power transfer efficiency and managing the increased complexity in packaging and matching circuitry are also discussed.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and MaterialsBio-Electronic
Highly efficient laser-driven Compton gamma-ray source
No full textThe recent advancement of high-intensity lasers has made all-optical Compton scattering become a promising way to produce ultrashort brilliant gamma-rays in an ultra-compact system. However, so far achieved Compton gamma-ray sources are limited by low conversion efficiency and spectral intensity. Here we present a highly efficient gamma photon emitter obtained by irradiating a high-intensity laser pulse on a miniature plasma device consisting of a plasma lens and a plasma mirror. This concept exploits strong spatiotemporal laser-shaping process and high-charge electron acceleration process in the plasma lens, as well as an efficient nonlinear Compton scattering process enabled by the plasma mirror. Our full three-dimensional particle-in-cell simulations demonstrate that in this novel scheme, brilliant gamma-rays with very high conversion efficiency (higher than 10(-2)) and spectral intensity (similar to 10(9) photons/0.1%BW) can be achieved by employing currently available petawatt-class lasers with intensity of 10(21) W cm(-2). Such efficient and intense gamma-ray sources would find applications in wide-ranging areas. ©2019 The Author(s)
Customized Corneal Cross-linking: One-Year Results.
No full textPURPOSE
To compare the efficacy of customized corneal cross-linking (CXL) with standard CXL.
DESIGN
Prospective, nonrandomized comparative clinical study.
METHODS
In a prospective study at the Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Zurich, Switzerland, 40 eyes of 40 patients with documented progressive primary keratoconus were treated with customized CXL (n = 20) or standard CXL (n = 20) and followed for 1 year. Customized irradiation patterns had an energy fluence of 9 mW/cm(2) and total energy levels ranging from 5.4 J/cm(2) up to 10 J/cm(2) and were centered on the maximum of the posterior float. The control group received homogenous irradiation with a fluence of 9 mW/cm(2) and a total energy of 5.4 J/cm(2). Scheimpflug tomographies, endothelium cell count, best spectacle-corrected visual acuity (BSCVA), and anterior segment optical coherence tomography (OCT) were compared preoperatively and 1 year postoperatively.
RESULTS
Pachymetry and ΔKmax showed significant changes 1 year postoperatively within each group. Epithelial healing time, ΔKmax, and regularization index (RI) were significantly better in the customized CXL group. Two out of 19 eyes (11%) in the standard group but 7 out of 19 eyes (37%) in the customized CXL group showed a flattening of 2 or more diopters (P = .03). The RI was 5.2 ± 2.7 D in the customized group vs 4.1 ± 3.1 D in the control group (P = .03). Statistically significant correlations between RI and preoperative Kmax, preoperative pachymetry, and preoperative posterior float were found only in the customized group.
CONCLUSIONS
Customized CXL seems to be as safe as standard CXL with stronger flattening in Kmax and RI, and a faster epithelial healing period
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