814 research outputs found
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Optical coherence tomography applied to investigations of optical properties of paintings
Optical Coherence Tomography (OCT), a fast 3D scanning Michelson interferometer normally applied to biomedical applications has recently been applied to art related subjects. In this thesis, the various applications of OCT to the non invasive imaging of paintings are explored in detail. The spectral reflectance and transparency of a variety of historic artistsâ pigments in linseed oil or egg tempera medium are investigated and the best spectral window is found for OCT imaging of paintings. Different methods of OCT measurements of refractive indices of paint layers are presented. The first attempt of monitoring the cleaning treatment of a painting was presented in order to detect whether there was a change in the original paint surface after solvent cleaning of old varnish layers above the paint surface. Methods of revealing underdrawings (preparatory sketches) below the paint layers using OCT are explored to obtain the highest contrast images of underdrawings. One of the largest OCT underdrawing images is presented for the first time
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Pigment identification with optical coherence tomography and multispectral imaging
We describe a new method for non-invasive pigment identification by combining the spectral reflectance in the visible spectrum with near infrared OCT cross-section images of the subsurface layer structure
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Non-invasive imaging of subsurface paint layers with optical coherence tomography
Optical coherence tomography (OCT) systems are fast scanning infrared Michelson interferometers designed for the non-invasive examination of the interiors of the eye and subsurface structures of biological tissues. OCT has recently been applied to the non-invasive examinations of the stratigraphy of paintings and museum artefacts. So far this is the only technique capable of imaging non-invasively the subsurface structure of paintings and painted objects. Unlike the traditional method of paint cross-section examination where sampling is required, the non-invasive and non-contact nature of the technique enables the examination of the paint cross-section anywhere on a painting, as there is no longer an issue with conservation ethics regarding the taking of samples from historical artefacts. A range of applications of the technique including the imaging of stratigraphy of paintings and painted artefacts, the imaging of underdrawings to the analysis of the optical properties of paint and varnish layers is presented. Future projects on the application of OCT to art conservation are discussed
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Optical coherence tomography - a tool for high resolution non-invasive 3D-imaging of the subsurface structure of paintings
Optical Coherence Tomography (OCT) is an imaging technique originally developed for high-resolution 3D imaging of the human eye. In 2004, Targowski et al. and Liang et al. first reported its application to paintings, demonstrating that it was possible to produce cross-section images noninvasively with this technique. In 2005 Liang et al. explored further applications such as imaging of underdrawing at a resolution and contrast greater than that achievable with infrared reflectography Since then the authors have been conducting a project to investigate systematically the potential of O C T as a new tool in the non-invasive examination of paintings and to design an O C T optimised for use in museums. This paper discusses recent developments in this work and presents examples of the use of O CT on paintings undergoing conservation treatment in the National Gallery, London
Effects of Alfaxalone or Propofol on Giant-Breed Dog Neonates Viability During Elective Caesarean Sections
Nowadays, thanks to the increased awareness of owners and breeders and to the most recent techniques available to veterinarians, the management of parturition, especially of C-sections, has become a topic of greater importance. Anesthesia is crucial and must be targeted to both the mother and neonates. The present study aimed to evaluate the effect of the induction agent alfaxalone on the vitality of puppies born from elective C-section, in comparison to propofol. After inducing general anesthesia for elective C-section, puppies from the mothers induced with alfaxalone had higher 5-min Apgar scores than those induced with propofol. The concentration of cortisol in fetal fluids collected at birth is neither influenced by the anesthetic protocol used, nor does it differ between amniotic and allantoic fluids. Nevertheless, the cortisol concentration in fetal fluids affects the relationship between anesthesia and the Apgar score: the present study highlights a significant relationship between the anesthetic protocol used and Apgar score in puppies, and fetal fluids cortisol concentration acts as a covariate of this relationship. Alfaxalone is a safe and effective drug for the induction of anesthesia in dogs, and it can be successfully employed for elective C-section, with neonatal wellbeing improvements
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Optical coherence tomography for art conservation and archaeology
Optical coherence tomography (OCT) is a fast scanning Michelson interferometer originally designed for in vivo imaging of the eye. In 2004, our group along with two other groups first reported the application of OCT to art conservation and archaeology. Since that time we have been conducting a project to investigate systematically the potential of OCT as a new tool for non-invasive examinations of a wide range of museum objects and to design an OCT optimised for in situ use in museums. Here we present the latest results from this ongoing project, which include the determination of the optimum spectral windows for OCT imaging of paintings and painted objects executed using traditional techniques, and non-invasive imaging of the subsurface stratigraphy of painted layers at multiple wavelengths. OCT imaging in assisting spectral pigment identification and in measuring refractive indices of paint will also be presented to illustrate the potential of the technique
A post-IR IRSL chronology and dustmass accumulation rates of the Nosak loess-palaeosol sequence in northeastern Serbia
In the Middle Danube Basin, Quaternary deposits are widely distributed in the Vojvodina region where they cover
about 95% of the area.Major research during the last two decades has been focused on loess deposits in the Vojvodina
region. During this period, loess in the Vojvodina region has become one of the most important Pleistocene European
continental climatic and environmental records.Herewe present the dating results of 15 samples taken from theNosak
loess-palaeosol sequence in northeastern Serbia in order to establish a chronology over the last three glacialâ
interglacial cycles. We use the pIRIR290 signal of the 4â11 lm polymineral grains. The calculated ages are within the
error limits partially consistent with the proposed multi-millennial chronostratigraphy for Serbian loess. The average
mass accumulation rate for the last three glacialâinterglacial cycles is 265 g mďż˝2 aďż˝1
, which is in agreement with the
values of most sites in the Carpathian Basin. Our results indicate a highly variable deposition rate of loess, especially
during the MIS 3 and MIS 6 stages, which is contrary to most studies conducted in Serbia where linear sedimentation
rates were assume
Development of a modular test system for the silicon sensor R&D of the ATLAS Upgrade
High Voltage CMOS sensors are a promising technology for tracking detectors in collider experiments. Extensive R&D studies are being carried out by the ATLAS Collaboration for a possible use of HV-CMOS in the High Luminosity LHC upgrade of the Inner Tracker detector. CaRIBOu (Control and Readout Itk BOard) is a modular test system developed to test Silicon based detectors. It currently includes five custom designed boards, a Xilinx ZC706 development board, FELIX (Front-End LInk eXchange) PCIe card and a host computer. A software program has been developed in Python to control the CaRIBOu hardware. CaRIBOu has been used in the testbeam of the HV-CMOS sensor AMS180v4 at CERN. Preliminary results have shown that the test system is very versatile. Further development is ongoing to adapt to different sensors, and to make it available to various lab test stands
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