2,912 research outputs found
Characterization and digital restauration of XIV-XV centuries written parchments by means of non-destructive techniques. Three case studies
Parchment is the primary writing medium of the majority of documents with cultural importance. Unfortunately, this material suffers of several mechanisms of degradation that affect its chemical-physical structure and the readability of text. Due to the unique and delicate character of these objects, the use of nondestructive techniques is mandatory. In this work, three partially degraded
handwritten parchments dating back to the XIV-XV centuries were analyzed by means of X-ray fluorescence spectroscopy, µ-ATR Fourier transform infrared spectroscopy, and reflectance and UV-induced fluorescence spectroscopy. 'e elemental and molecular results provided the identification of the inks, pigments, and superficial treatments. In particular, all manuscripts have been written with iron gall inks, while the capital letters have been realized with cinnabar and azurite. Furthermore, multispectral UV fluorescence imaging and multispectral VIS-NIR imaging proved to be a good approach for the digital restoration of manuscripts that suffer from the loss of inked areas or from the presence of brown spotting. Indeed, using ultraviolet radiation and collecting the images at different spectral ranges is possible to enhance the readability of the text, while by illuminating with visible light and by collecting the images at longer wavelengths, the hiding effect of brown spots can be attenuated
Accuracy of three electronic apex locators in anterior and posterior teeth: an ex-vivo study.
Abstract
Introduction: The aim of this study was to determine in
anterior teeth, bicuspids, and molars (1) the accuracy of
3 different electronic apex locators (EALs) in detecting
the apical foramen and (2) the accuracy of digital radiography
in determining the working length (WL),
compared with visible control under a microscope.
Methods: By using radiovideography (RVG), we
measured the lengths of 120 root canals with 3 different
EALs (Endex, ProPex II, and Root ZX) and compared
them with the actual lengths. The accuracy of EALs
and RVG was related to each dental category. An
endodontic training kit (Pro-Train) was used during
experimental procedures. Results: Statistical analysis
showed that the 3 EALs and RVG were less accurate
in anterior teeth and molars than in bicuspids. The
paired-sample t test showed no statistically significant
difference between mesiodistal plane and buccolingual
plane digital radiography in all groups. Conclusions:
The 3 EALs tested were more accurate in detecting the
apical foramen in bicuspids than in both molars and
anterior teeth. Radiographic measurements were not
reliable for determining WL in all dental groups in
both radiographic planes. (J Endod 2011;37:684–687
Precisione nella determinazione della lunghezza di lavoro mediante localizzatori elettronici d’apice, radiologia digitale e prova visiva: presentazione di una nuova metodica sperimentale di indagine – uno studio ex-vivo. Exact determination of the working length by electronic apex locators, digital radiology, and visual test: presentation of a new experimental research strategy – an ex-vivo study.
Abstract
Objectives: This study compared: 1) the accuracy of three different electronic apex locators
(EALs) in detecting the apical foramen ex-vivo under clinical conditions; 2) the accuracy of digital
radiography and EALs in determining the K-file position in the root canal; 3) the accuracy of two
different radiographic planes; (4) the precision of #10, #15, and #20 K-files in electronic
measurements; 5) the precision of EALs in relation to the dental anatomy classification (anterior,
bicuspids, and molars).
Materials and methods: The length of 101 extracted human teeth was measured with three
different EALs (Endex, Propex II and Root ZX), with RVG and compared to the actual length.
Experimental procedures were performed using an endodontic training kit (Pro-Train).
Results: The statistical analysis showed that Endex and Propex II were more accurate than Root
ZX in determining the working length (WL). The t-test showed no statistically significant
difference of accuracy between the two radiographic planes examined. The t-test showed no
significant difference between the three different K-file size measurements. EALs and RVG are
less accurate in anterior teeth.
Conclusions: To prevent overestimation of the root canal length using the EALs tested, 1 mm
should be subtracted from the measurement on the ‘‘APEX’’ mark. Instrument sizes did not affect
the accuracy of EALs. EALs showed to be more accurate in determining the WL than RVG.
2011 Societa` Italiana di Endodonzia. Published by Elsevier Srl. All rights reserved
Real time control of EC heating & current drive systems on TCV
The ability to control, in real time, the electron cyclotron heating & current drive systems for the control of MHD instabilities is particularly important for large tokamaks operating at high performance. Several algorithms have been developed and tested on TCV to explore possible control techniques, first in simple experiments to control the plasma current and elongation and subsequently in experiments to control the sawtooth instability and profile parameters. A summary of these experiments are presented in this paper together with the application of the break-in-slope technique as a possible real time calculation of the location of EC deposition
Temporal response to harmonic driving in electroconvection
The temporal evolution of the spatially periodic electroconvection (EC)
patterns has been studied within the period of the driving ac voltage by
monitoring the light intensity diffracted from the pattern. Measurements have
been carried out on a variety of nematic systems, including those with negative
dielectric and positive conductivity anisotropy, exhibiting "standard EC"
(s-EC), those with both anisotropies negative exhibiting "non-standard EC"
(ns-EC), as well as those with the two anisotropies positive. Theoretical
predictions have been confirmed for stationary s-EC and ns-EC patterns.
Transitions with Hopf bifurcation have also been studied. While traveling had
no effect on the temporal evolution of dielectric s-EC, traveling conductive
s-EC and ns-EC patterns exhibited a substantially altered temporal behavior
with a dependence on the Hopf frequency. It has also been shown that in
nematics with both anisotropies positive, the pattern develops and decays
within an interval much shorter than the period, even at relatively large
driving frequencies.Comment: 19 pages, 5 figure
Precisione nella determinazione della lunghezza di lavoro mediante localizzatori elettronici d’apice, radiologia digitale e prova visiva: presentazione di una nuova metodica sperimentale di indagine — uno studio ex-vivo. Exact determination of the working length by electronic apex locators, digital radiology, and visual test: presentation of a new experimental research strategy — an ex-vivo study.
The OPERA magnetic spectrometer
The OPERA neutrino oscillation experiment foresees the construction of two
magnetized iron spectrometers located after the lead-nuclear emulsion targets.
The magnet is made up of two vertical walls of rectangular cross section
connected by return yokes. The particle trajectories are measured by high
precision drift tubes located before and after the arms of the magnet.
Moreover, the magnet steel is instrumented with Resistive Plate Chambers that
ease pattern recognition and allow a calorimetric measurement of the hadronic
showers. In this paper we review the construction of the spectrometers. In
particular, we describe the results obtained from the magnet and RPC prototypes
and the installation of the final apparatus at the Gran Sasso laboratories. We
discuss the mechanical and magnetic properties of the steel and the techniques
employed to calibrate the field in the bulk of the magnet. Moreover, results of
the tests and issues concerning the mass production of the Resistive Plate
Chambers are reported. Finally, the expected physics performance of the
detector is described; estimates rely on numerical simulations and the outcome
of the tests described above.Comment: 6 pages, 10 figures, presented at the 2003 IEEE-NSS conference,
Portland, OR, USA, October 20-24, 200
- …