8,120 research outputs found
A singular integration by parts formula for the exponential Euclidean QFT on the plane
We give a novel characterization of the Euclidean quantum field theory with
exponential interaction on through a renormalized
integration by parts (IbP) formula, or otherwise said via an Euclidean
Dyson-Schwinger equation for expected values of observables. In order to obtain
the well-posedness of the singular IbP problem, we import some ideas used to
analyse singular SPDEs and we require the measure to "look like" the Gaussian
free field (GFF) in the sense that a suitable Wasserstein distance from the GFF
is finite. This guarantees the existence of a nice coupling with the GFF which
allows to control the renormalized IbP formula.Comment: 78 page
Patient organ and effective dose estimation in CT: comparison of four software applications
Background: Radiation dose in computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. Hence, dose tracking and organ dose calculation software are increasingly used. We evaluated the organ dose variability associated with the use of different software applications or calculation methods.
Methods: We tested four commercial software applications on CT protocols actually in use in our hospital: CT-Expo, NCICT, NCICTX, and Virtual Dose. We compared dose coefficients, estimated organ doses and effective doses obtained by the four software applications by varying exposure parameters. Our results were also compared with estimates reported by the software authors.
Results: All four software applications showed dependence on tube voltage and volume CT dose index, while only CT-Expo was also dependent on other exposure parameters, in particular scanner model and pitch caused a variability till 50%. We found a disagreement between our results and those reported by the software authors (up to 600%), mainly due to a different extent of examined body regions. The relative range of the comparison of the four software applications was within 35% for most organs inside the scan region, but increased over the 100% for organs partially irradiated and outside the scan region. For effective doses, this variability was less evident (ranging from 9 to 36%).
Conclusions: The two main sources of organ dose variability were the software application used and the scan region set. Dose estimate must be related to the process used for its calculation
SIR-C/X-SAR data calibration and ground truth campaign over the NASA-CB1 test-site
During the Space Shuttle Endeavour mission in October 1994, a remote-sensing campaign was carried out with the objectives of both radiometric and polarimetric calibration and ground truth data acquisition of bare soils. This paper presents the results obtained in the experiment. Polarimetric cross-talk and channel imbalance values, as well as radiometric calibration parameters, have been
found to be within the science requirements for SAR images. Regarding ground truth measurements, a wide spread in the height rms values and correlation lengths has been observed, which has motivated a critical revisiting of surface parameters descriptors
Performance of three model-based iterative reconstruction algorithms using a CT task-based image quality metric
In this study we evaluated the task-based image quality of a low contrast
clinical task for the abdomen protocol (e.g., pancreatic tumour) of three
different CT vendors, exploiting three model-based iterative reconstruction
(MBIR) levels. We used three CT systems equipped with a full, partial, advanced
MBIR algorithms. Acquisitions were performed on a phantom at three dose levels.
Acquisitions were reconstructed with a standard kernel, using filtered back
projection algorithm (FBP) and three levels of the MBIR. The noise power
spectrum (NPS), the normalized one (nNPS) and the task-based transfer function
(TTF) were computed following the method proposed by the American Association
of Physicists in Medicine task group report-233 (AAPM TG-233). Detectability
index (d') of a small lesion (small feature; 100 HU and 5-mm diameter) was
calculated using non-prewhitening with eye-filter model observer (NPWE).The
nNPS, NPS and TTF changed differently depending on CT system. Higher values of
d' were obtained with advanced-MBIR, followed by full-MBIR and
partial-MBIR.Task-based image quality was assessed for three CT scanners of
different vendors, considering a clinical question. Detectability can be a tool
for protocol optimisation and dose reduction since the same dose levels on
different scanners correspond to different d' values.Comment: 7 pages, 5 figures, 3 table
Utilização de xiloglucana na embriogênese somática a partir de embriões zigóticos de dendezeiro (Elaeis guineensis Jacq.).
O objetivo deste trabalho foi testar diferentes meios de cultura contendo misturas de XG e de Gelrite
Geological, seismological and geodetic evidence of active thrustingand folding south of Mt. Etna (eastern Sicily): Revaluation of “seismicefficiency” of the Sicilian Basal Thrust
tGeological studies and morphological analysis, compared with seismological and geodetic data, suggestthat a compressive regime currently occurs at crustal depth in the western sector of Mt. Etna, accommo-dated by shallow thrusting and folding at the front of the chain, south of the volcanic edifice. In particular,a large WSW-ENE trending anticline, interpreted as detachment fold, is growing west and north of Cata-nia city (the Catania anticline). Geological data suggest that during the last 6000 years the frontal foldhas been characterized by uplift rates of ∼6 mm/yr along the hinge, consistent with the interferometricdata (10 mm/yr) recorded in the last 20 years. Moreover, a NNW-SSE oriented axis of compression hasbeen obtained by seismological data, consistent with GPS measurements over the last 20 years whichhave revealed a shortening rate of ∼5 mm/yr along the same direction. Besides the activity related to thevolcanic feeding system, the seismic pattern under the Mt. Etna edifice can be certainly related to theregional tectonics. The compressive stress is converted into elastic accumulation and then in earthquakesalong the ramps beneath the chain, whereas on the frontal area it is accommodated by aseismic defor-mation along an incipient detachment within the clayish foredeep deposits. The high rate of shorteningat the aseismic front of the chain, suggests a greater “seismic efficiency” in correspondence of ramps atthe rear.Published32-412T. Tettonica attivaJCR Journalrestricte
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