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Superfluorescence from Magnetically Formed Quantum Dots: the Excitation Pulse-Width Dependence
조영달,이진호,Gary D. Sanders,Christopher J. Stanton,David H. Reitze,Junichiro Kono,Alexey A. Belyanin 한국광학회 2008 Current Optics and Photonics Vol.12 No.1
We investigated the laser pulse-width dependence of dense plasmas confined within the magnetic length of In0.2Ga0.8As/GaAs multiple quantum wells under high magnetic fields up to 31 T. To fully fill the Landau levels of effectively zero-dimensional system, we used intense femtosecond (fs) laser pulses to create carrier densities near 1013/cm2. The observed photoluminescence showed a characteristic of superfluorescence, above critical magnetic field when being excited by pulses shorter than coherence buildup time.
Orhan Kaan,Orhan Kaan,Manulis David,Golitsyna Maria,Bayrak Seval,Aksoy Secil,Sanders Alex,Önder Merve,Ezhov Matvey,Shamshiev Mamat,Gusarev Maxim,Shlenskii Vladislav 대한영상치의학회 2023 Imaging Science in Dentistry Vol.53 No.3
Purpose: The objective of this study was to evaluate the accuracy and effectiveness of an artificial intelligence (AI) program in identifying dental conditions using panoramic radiographs (PRs), as well as to assess the appropriateness of its treatment recommendations. Materials and Methods: PRs from 100 patients (representing 4497 teeth) with known clinical examination findings were randomly selected from a university database. Three dentomaxillofacial radiologists and the Diagnocat AI software evaluated these PRs. The evaluations were focused on various dental conditions and treatments, including canal filling, caries, cast post and core, dental calculus, fillings, furcation lesions, implants, lack of interproximal tooth contact, open margins, overhangs, periapical lesions, periodontal bone loss, short fillings, voids in root fillings, overfillings, pontics, root fragments, impacted teeth, artificial crowns, missing teeth, and healthy teeth. Results: The AI demonstrated almost perfect agreement (exceeding 0.81) in most of the assessments when compared to the ground truth. The sensitivity was very high (above 0.8) for the evaluation of healthy teeth, artificial crowns, dental calculus, missing teeth, fillings, lack of interproximal contact, periodontal bone loss, and implants. However, the sensitivity was low for the assessment of caries, periapical lesions, pontic voids in the root canal, and overhangs. Conclusion: Despite the limitations of this study, the synthesized data suggest that AI-based decision support systems can serve as a valuable tool in detecting dental conditions, when used with PR for clinical dental applications.
Shivanand Bomman,Sofya Malashanka,Adil Ghafoor,David J. Sanders,Shayan Irani,Richard A. Kozarek,Andrew Ross,Michal Hubka,Rajesh Krishnamoorthi 대한소화기내시경학회 2022 Clinical Endoscopy Vol.55 No.5
Background/Aims: Transoral incisionless fundoplication (TIF) is an accepted anatomic treatment for gastroesophageal reflux disease in selected patients. In this report, we analyze our institution’s programmatic allocation of resources during the safe implementation of TIF as a new procedure. Methods: A retrospective analysis of all patients who underwent TIF from January 2020 to February 2021 at our institution was per- formed. The process of initially allocating the operating room (OR) with overnight admission and postoperative esophagram for added safety, and subsequently transitioning TIF to the endoscopy suite (ES) as an outpatient procedure was described. Patient safety and out- comes were evaluated during transition. Results: Thirty patients who underwent TIF were identified. The mean age was 51.2±16.0 years. TIF was performed in an OR in nine patients (30%) and 21 (70%) in the ES. All the OR patients were admitted overnight and had routine esophagogram. In contrast, four (19%) from the ES group required clinically-indicated admission and three (14.2%) required esophagram. The mean procedure dura- tion was significantly lower in the ES group (65.7 min vs. 84 min, p=0.02). Conclusions: A stepwise, resource-efficient process was described that allowed safe initiation of TIF as a new technique and its effec- tive transition to a fully outpatient procedure.
Variability and quasi-decadal changes in the methane budget over the period 2000-2012
Saunois, Marielle,Bousquet, Philippe,Poulter, Ben,Peregon, Anna,Ciais, Philippe,Canadell, Josep G.,Dlugokencky, Edward J.,Etiope, Giuseppe,Bastviken, David,Houweling, Sander,Janssens-Maenhout, Greet,T Copernicus GmbH 2017 Atmospheric Chemistry and Physics Vol.17 No.18
<P>Abstract. Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH4) budget over 2000-2012 (Saunois et al., 2016), we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH4 emissions. The GCP dataset integrates results from top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models (including process-based models for estimating land surface emissions and atmospheric chemistry), inventories of anthropogenic emissions, and data-driven approaches. The annual global methane emissions from top-down studies, which by construction match the observed methane growth rate within their uncertainties, all show an increase in total methane emissions over the period 2000-2012, but this increase is not linear over the 13 years. Despite differences between individual studies, the mean emission anomaly of the top-down ensemble shows no significant trend in total methane emissions over the period 2000-2006, during the plateau of atmospheric methane mole fractions, and also over the period 2008-2012, during the renewed atmospheric methane increase. However, the top-down ensemble mean produces an emission shift between 2006 and 2008, leading to 22 [16-32] Tg CH4 yr−1 higher methane emissions over the period 2008-2012 compared to 2002-2006. This emission increase mostly originated from the tropics, with a smaller contribution from mid-latitudes and no significant change from boreal regions. The regional contributions remain uncertain in top-down studies. Tropical South America and South and East Asia seem to contribute the most to the emission increase in the tropics. However, these two regions have only limited atmospheric measurements and remain therefore poorly constrained. The sectorial partitioning of this emission increase between the periods 2002-2006 and 2008-2012 differs from one atmospheric inversion study to another. However, all top-down studies suggest smaller changes in fossil fuel emissions (from oil, gas, and coal industries) compared to the mean of the bottom-up inventories included in this study. This difference is partly driven by a smaller emission change in China from the top-down studies compared to the estimate in the Emission Database for Global Atmospheric Research (EDGARv4.2) inventory, which should be revised to smaller values in a near future. We apply isotopic signatures to the emission changes estimated for individual studies based on five emission sectors and find that for six individual top-down studies (out of eight) the average isotopic signature of the emission changes is not consistent with the observed change in atmospheric 13CH4. However, the partitioning in emission change derived from the ensemble mean is consistent with this isotopic constraint. At the global scale, the top-down ensemble mean suggests that the dominant contribution to the resumed atmospheric CH4 growth after 2006 comes from microbial sources (more from agriculture and waste sectors than from natural wetlands), with an uncertain but smaller contribution from fossil CH4 emissions. In addition, a decrease in biomass burning emissions (in agreement with the biomass burning emission databases) makes the balance of sources consistent with atmospheric 13CH4 observations. In most of the top-down studies included here, OH concentrations are considered constant over the years (seasonal variations but without any inter-annual variability). As a result, the methane loss (in particular through OH oxidation) varies mainly through the change in methane concentrations and not its oxidants. For these reasons, changes in the methane loss could not be properly investigated in this study, although it may play a significant role in the recent atmospheric methane changes as briefly discussed at the end of the paper. </P>