Static computer-assisted surgery (s-CAS) has been introduced to improve the results of implantology. A prospective cohort study was conducted following the STROBE guidelines to determine the presence ...of a learning curve in s-CAS. Six partially and six totally edentulous patients were treated by two surgeons experienced in implantology but completely inexperienced in s-CAS. Preoperative and postoperative computed tomography scans were matched to assess coronal, apical, and angular deviation and the positioning error. The accuracy data were used to evaluate the learning curve. Fifty-six implants were inserted. In partially and totally edentulous patients, the mean (range; standard deviation) coronal deviation was 0.87 (0.34–1.27; 0.35) and 1.24 (0.72–2.67; 0.79); the mean apical deviation was 1.13 (0.48–1.63; 0.39) and 1.52 (0.88–3.84; 1.15); the mean angular deviation was 2.63 (1.89–4.50; 0.98) and 3.59 (1.69–6.30; 1.65); and the mean positioning error was 0.80 (0.32–1.25; 0.35) and 1.14 (0.35–2.56; 0.77), respectively. A typical ‘learning curve’ effect was not identified for s-CAS.
The aim of this report was to describe a new computer-guided technique for a controlled site preparation and palatal orthodontic miniscrew insertion using a dedicated software. A surgical guide was ...designed after planning the appropriate insertion sites on three-dimensional images created by the fusion of cone-beam computed tomography (CBCT) and digital dental model images. Pre- and postoperative CBCT images were compared and the angular, coronal, and apical deviations between the planned and the placed miniscrews were calculated. The mean coronal and apical deviations were 1.38mm (range: 3.48–0.15mm; standard deviation (SD): 0.65) and 1.73mm (range: 5.41–0.10mm; SD: 1.03), respectively, while the mean angular deviation was 4.60° (range: 15.23–0.54°; SD: 2.54). The present surgical guide allows a controlled and accurate palatal miniscrew placement in three dimensions.
Abstract The brass wire ligature is an efficient method to correct a moderately mesially impacted mandibular second molar (MM2). The aim of this prospective clinical pilot study was to evaluate the ...influence of mandibular third molar (MM3) germectomy on the treatment time for this procedure and to determine its impact on oral health-related quality of life (OHRQoL) using the short-form Oral Health Impact Profile (OHIP-14). The STROBE guidelines were followed. Impacted MM2 were assigned randomly to receive brass wire ligature treatment either with germectomy (group A) or without germectomy (group B). Descriptive statistics and the Student t -test were used in the statistical analysis; significance was set at P ≤ 0.05. One thousand and thirty patients were assessed. Fourteen subjects with 20 mesially angulated (range 25–40°) impacted MM2 were identified. Paired comparisons of groups A and B showed no statistically significant difference in treatment time (171 days for group A and 174 days for group B; P = 0.440), but a statistically significant difference in OHIP-14 values at the 3- ( P = 0.017) and 7-day ( P = 0.002) follow-up. The brass wire technique can be used effectively in moderately impacted MM2, but the combined use of MM3 germectomy does not influence the treatment time and shows a negative impact on OHRQoL.
•We calculate and map the solar hemispherical albedo of Mars surface using OMEGA.•Several surface change types and timings are detected.•Thin layers of dust can mask underlying mineralogical near-IR ...spectral signatures.
The pervasive Mars dust is continually transported between the surface and the atmosphere. When on the surface, dust increases the albedo of darker underlying rocks and regolith, which modifies climate energy balance and must be quantified. Remote observation of surface albedo absolute value and albedo change is however complicated by dust itself when lifted in the atmosphere. Here we present a method to calculate and map the bolometric solar hemispherical albedo of the martian surface using the 2004–2010 OMEGA imaging spectrometer dataset. This method takes into account aerosols radiative transfer, surface photometry, and instrumental issues such as registration differences between visible and near-IR detectors. Resulting albedos are on average 17% higher than previous estimates for bright surfaces while similar for dark surfaces. We observed that surface albedo changes occur mostly during the storm season due to isolated events. The main variations are observed during the 2007 global dust storm and during the following year. A wide variety of change timings are detected such as dust deposited and then cleaned over a martian year, areas modified only during successive global dust storms, and perennial changes over decades. Both similarities and differences with previous global dust storms are observed. While an optically thin layer of bright dust is involved in most changes, this coating turns out to be sufficient to mask underlying mineralogical near-IR spectral signatures. Overall, changes result from apparently erratic events; however, a cyclic evolution emerges for some (but not all) areas over long timescales.
We here reassess the global distribution of several key mineral species using the entire OMEGA/Mars Express VIS‐NIR imaging spectrometer data set, acquired from orbit insertion in January 2004 to ...August 2010. Thirty‐two pixels per degree global maps of ferric oxides, pyroxenes and olivines have been derived. A significant filtering process was applied in order to exclude data acquired with unfavorable observation geometries or partial surface coverage with water and CO2 frosts. Because of strong atmospheric variations over the 3.6 Martian years of observations primarily due to the interannual variability of the aerosol opacity, a new filter based on the atmospheric dust opacity calibrated by the Mars Exploration Rovers measurements has also been implemented. The Fe3+absorption features are present everywhere on the surface, with a variety of intensities indicating distinct formation processes. The pyroxene‐bearing regions are localized in low albedo regions, while the bright regions are spectrally comparable to anhydrous nanophase ferric oxides. The expanded data set increases by a factor of about 2, the number of olivine detections reported in previous OMEGA‐based studies. Olivine is mainly detected in three types of areas over the Martian surface: discontinuous patches on the terraces of the three main basins; smooth inter‐crater plains and smooth crater floors throughout the southern highlands; and crater sand dunes, crater ejectas and extended bedrock exposures in the northern plains. Olivine is also detected in the low albedo pyroxene‐bearing dunes surrounding the northern polar cap.
Key Points
Global distribution of several key mineral species of the Martian surface
Use of the full OMEGA data set
Significant filtering process applied on data
•Putative hydrothermal deposits are found in Auki crater.•Formation and post impact hydrous environments in Thyrrena Terra, Mars.•Impact-generated hydrothermal alteration formed phyllosilicates, ...carbonates, zeolites, chlorites, serpentines and opals.•New evidence for impact-generated hydrothermal systems on Mars is presented using CRISM and HiRISE data.
A variety of hydrothermal environments have been documented in terrestrial impact structures. Due to both past water interactions and meteoritic bombardment on the surface of Mars, several authors have predicted various scenarios that include the formation of hydrothermal systems. Geological and mineralogical evidence of past hydrothermal activity have only recently been found on Mars. Here, we present a geological and mineralogical study of the Auki Crater using the spectral and visible imagery data acquired by the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars), CTX (Context Camera) and HiRISE (High Resolution Imaging Science Experiment) instruments on board the NASA MRO mission.
The Auki Crater is a complex crater that is ∼38km in diameter located in Tyrrhena Terra (96.8°E and 15.7°S) and shows a correlation between its mineralogy and morphology. The presence of minerals, such as smectite, silica, zeolite, serpentine, carbonate and chlorite, associated with morphological structures, such as mounds, polygonal terrains, fractures and veins, suggests that the Auki Crater may have hosted a post impact-induced hydrothermal system. Although the distribution of hydrated minerals in and around the central uplift and the stratigraphic relationships of some morphological units could also be explained by the excavation and exhumation of carbonate-rich bedrock units as a consequence of crater formation, we favor the hypothesis of impact-induced hydrothermal circulation within fractures and subsequent mineral deposition. The hydrothermal system could have been active for a relatively long period of time after the impact, thus producing a potential transient habitable environment.
The aim of this study was to evaluate the effectiveness of loading at 2 months after the surgical placement of implants. A tapered implant was used. Implant stability was determined using resonance ...frequency analysis at implant insertion (T0; primary stability), after 2 months (T1), and at the 6-month follow-up (T2). Descriptive statistics and the t-test were used. Significance was at P ≤ 0.05. A total of 268 implants were inserted in 142 patients. No patient dropped out and no implant had failed at the 6-month follow-up. The mean implant stability quotient value (ISQ) increased over time, with a statistically non-significant difference for T0 vs. T1 (P = 0.08) and a statistically significant difference for T1 vs. T2 (P = 0.0018) and T0 vs. T2 (P = 0.000). Only 99 implants, characterized by an extremely high mean primary stability value (80.34), did not have a recorded increase in ISQ at T1. A 2-month healing period allowed the implant to achieve secondary stability, confirming the effectiveness of the loading protocol at 2 months.
Olivine and Pyroxene Diversity in the Crust of Mars Mustard, J. F; Poulet, F; Gendrin, A ...
Science (American Association for the Advancement of Science),
03/2005, Letnik:
307, Številka:
5715
Journal Article
Recenzirano
Odprti dostop
Datafromthe Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) on the Mars Express spacecraft identify the distinct mafic, rock-forming minerals olivine, low-calcium ...pyroxene (LCP), and high-calcium pyroxene (HCP) on the surface of Mars. Olivine- and HCP-rich regions are found in deposits that span the age range of geologic units. However, LCP-rich regions are found only in the ancient Noachian-aged units, which suggests that melts for these deposits were derived from a mantle depleted in aluminum and calcium. Extended dark regions in the northern plains exhibit no evidence of strong mafic absorptions or absorptions due to hydrated materials.
JUNO/JIRAM's view of Jupiter's H 3 + emissions Dinelli, B M; Adriani, A; Mura, A ...
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
2019-Sep-23, 2019-09-23, Letnik:
377, Številka:
2154
Journal Article
Recenzirano
Odprti dostop
The instrument JIRAM (Jovian Infrared Auroral Mapper), on board the NASA spacecraft Juno, is both an imager and a spectrometer. Two distinct detectors are used for imaging and spectroscopy. The ...imager acquires Jupiter images in two bands, one of which (L band, 3.3-3.6 μm) is devoted to monitor the H
emission. The spectrometer covers the spectral region from 2 to 5 μm (average spectral resolution 9 nm) with a 256 pixels slit that can observe the same scene of the L band imager with some delay. JIRAM scientific goals are the exploration of the Jovian aurorae and the planet's atmospheric structure, dynamics and composition. Starting early July 2016 Juno is orbiting around Jupiter. Since then, JIRAM has provided an unprecedented amount of measurements, monitoring both Jupiter's atmosphere and aurorae. In particular, the camera has monitored Jupiter's poles with very high spatial resolution, providing new insights in both its aurorae and the polar dynamic. The main findings obtained by the L imager are detailed pictures of Jupiter's aurorae showing an extremely complex morphology of the H
distribution in the main oval and in the moon's footprints. The spectrometer has enabled the measure the distribution of both H
concentration and temperature. The analysis of the north auroral region limb observations shows that the peak density of H
is above 750 km and that often it is anticorrelated to the temperature, confirming the infrared cooling effect of H
. This article is part of a discussion meeting issue 'Advances in hydrogen molecular ions: H
, H
and beyond'.
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