Multiplane iterative phase retrieval is a promising approach to diffraction imaging, which accurately determines the topographic and internal characteristics of various objects. Nevertheless, the detection systems used often have a limited dynamic range, resulting in overexposure of recorded intensity distributions. In this Letter, we present a novel, to the best of our knowledge, reconstruction algorithm that inpaints saturated areas on the measured intensity datasets and reliably retrieves wave complex amplitude.
View Article and Find Full Text PDFTerahertz phase retrieval is a promising technique able to assess the complex diffracted wave properties through an iterative processing algorithm. In this Letter, we demonstrate the implementation of this technique in reflection geometry with a continuous wave acquisition system working at 0.287 THz.
View Article and Find Full Text PDFTerahertz technologies are attracting strong interest from high-end industrial fields, and particularly for non-destructive-testing purposes. Currently lacking compactness, integrability as well as adaptability for those implementations, the development and commercialisation of more efficient sources and detectors progressively ensure the transition toward applicative implementations, especially for real-time full-field imaging. In this work, a flexible illumination system, based on fast beam steering has been developed and characterized.
View Article and Find Full Text PDFThanks to significant advances in real-time terahertz imaging in terms of resolution and image quality, adapting and extending optical methods for 3D imaging at the millimeter scale is now promising. The shape-from-focus algorithm is a post-processing tool used in optical microscopy to reconstruct the external shape surface of a convex surface object. Images acquired at different distances from the object-side focal plane are implemented in this algorithm.
View Article and Find Full Text PDFTwo-dimensional (2D) terahertz imaging and 3D visualization suffer from severe artifacts since an important part of the terahertz beam is reflected, diffracted, and refracted at each interface. These phenomena are due to refractive index mismatch and reflection in the case of non-orthogonal incidence. This paper proposes an experimental procedure that reduces these deleterious optical refraction effects for a cylinder and a prism made with polyethylene material.
View Article and Find Full Text PDFAdditive manufacturing (AM) technology is not only used to make 3D objects but also for rapid prototyping. In industry and laboratories, quality controls for these objects are necessary though difficult to implement compared to classical methods of fabrication because the layer-by-layer printing allows for very complex object manufacturing that is unachievable with standard tools. Furthermore, AM can induce unknown or unexpected defects.
View Article and Find Full Text PDFWe investigate in this paper a new reconstruction method in order to perform 3D Terahertz (THz) tomography using a continuous wave acquisition setup in transmission mode. This method is based on the Maximum Likelihood for TRansmission tomography (ML-TR) first developed for X-ray imaging. We optimize the Ordered Subsets Convex (OSC) implementation of the ML-TR by including the Gaussian propagation model of THz waves and take into account the intensity distributions of both blank calibration scan and dark-field measured on THz detectors.
View Article and Find Full Text PDFThe Rainfall Runoff Library (RRL) provides a convenient platform for implementing environment modelling components such as rainfall runoff models, calibration tools, and objective functions. A rainfall-runoff model widely known and used in South Korea, TANK, is added to the RRL, and used along with the models AWBM and SIMHYD to reproduce the historical time series of daily and monthly runoff at the Soyanggang Dam and Youngcheon Dam catchments located in South Korea. The features of the RRL allow for an easy comparison of different models in a standardised and common framework.
View Article and Find Full Text PDFActa Biotheor
November 1996
Patterns resulting from the sole interplay between reaction and diffusion are probably involved in certain stages of morphogenesis in biological systems, as initially proposed by Alan Turing. Self-organization phenomena of this type can only develop in nonlinear systems (i.e.
View Article and Find Full Text PDFIn seeking a method for the routine observation of copulatory behaviour in rats we compared the use of a standard rectangular Makrolon cage, commonly used in toxicology studies, with a Plexiglas cylinder that provided 2.5 times more floor area. The cylinder resulted in a much higher incidence of copulation, either once or for multiple series, within 30 min.
View Article and Find Full Text PDFTioconazole, an imidazole antifungal agent, was administered orally at 100 mg/kg/day to pregnant rats according to two regimens; in one, treatment started on day 15 post-insemination (p.i.) and in the other it started on day 18 p.
View Article and Find Full Text PDFReproductive toxicology studies were conducted in rabbits and rats given piroxicam, a non-steroidal anti-inflammatory agent (NSAI), orally at 2, 5 and 10 mg/kg/day. In teratology studies there was neither drug-related embryotoxicity nor teratogenicity. As piroxicam, like other NSAI, affects parturition in rats and leads to a progressive toxicity in lactating females, standard protocols were modified: dams of the female fertility study were treated from 2 weeks prior to mating until day 6 of gestation and females of the post-natal toxicity study were treated from parturition until day 12 of lactation.
View Article and Find Full Text PDFCumulative data are presented on the occurrence of external, skeletal and visceral abnormalities in foetuses from teratology studies conducted in New Zealand White rabbits over a 10-yr period. The data, based on examinations of over 5500 control foetuses and 19,000 foetuses from treated dams, are derived from studies involving 58 compounds, five of which were judged to be teratogenic.
View Article and Find Full Text PDFExtensive information was supplied about the frequencies and types of spontaneous skeletal and visceral malformations in control and test fetuses which may be encountered during teratological assays. Data were also provided on fertility, agerage body weights, water consumption as a function of diet, and food consumption. The two strains used, Crl:COBS CD (SD) BR (France) rats and Crl:CD-1 (ICR) BR (France) mice, are valuable research tools since they are prolific, have a low rate of spontaneous malformations, and are responsive to teratogenic agents.
View Article and Find Full Text PDF