385 research outputs found

    Detection and monitoring of forest fires using Himawari-8 geostationary satellite data in South Korea

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    Geostationary satellite remote sensing systems are a useful tool for forest fire detection and monitoring because of their high temporal resolution over large areas. In this study, we propose a combined 3-step forest fire detection algorithm (i.e., thresholding, machine learning-based modeling, and post processing) using Himawari-8 geostationary satellite data over South Korea. This threshold-based algorithm filtered the forest fire candidate pixels using adaptive threshold values considering the diurnal cycle and seasonality of forest fires while allowing a high rate of false alarms. The random forest (RF) machine learning model then effectively removed the false alarms from the results of the threshold-based algorithm (overall accuracy ~99.16%, probability of detection (POD) ~93.08%, probability of false detection (POFD) ~0.07%, and 96% reduction of the false alarmed pixels for validation), and the remaining false alarms were removed through post-processing using the forest map. The proposed algorithm was compared to the two existing methods. The proposed algorithm (POD ~ 93%) successfully detected most forest fires, while the others missed many small-scale forest fires (POD ~ 50-60%). More than half of the detected forest fires were detected within 10 min, which is a promising result when the operational real-time monitoring of forest fires using more advanced geostationary satellite sensor data (i.e., with higher spatial and temporal resolutions) is used for rapid response and management of forest fires

    The Clinical Significance of Intrarenal Reflux in Voiding Cystourethrography (VCUG)

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    PURPOSE: Intrarenal reflux (IRR) occurs in 3-10% of cases of total reflux and can lead to renal injury, which may eventually result in renal scarring. In this study, we evaluated the clinical importance of IRR detected by voiding cystourethrography and evaluated the relationship between IRR and renal scarring. MATERIALS AND METHODS: From January 2002 to May 2008, 50 patients who were diagnosed with vesicoureteral reflux (VUR) and showed IRR in voiding cystourethrography were enrolled. IRR was seen in 59 renal units in our enrolled patients. A 99mTc 2,3-dimercaptosuccinic acid (DMSA) renal scan was performed after VUR was detected in all cases. Nine patients were conservatively treated with prophylactic antibiotics, whereas 41 patients received an anti-reflux operation. A follow-up renal scan was performed after 3 to 6 months to check for any changes in renal scarring. RESULTS: The average patient age was 9.2 months (range, 1-42 months). Forty-nine patients were male; only one patient was female. The mean duration until surgery was 2.9 months. Generally, the IRR sites corresponded to the sites of photon defects on DMSA renal scans (76.3%). Furthermore, the photon defects on IRR sites tended to progress to renal scarring (65.2%). The rate of change in scarring was lower in the surgery group (47.1%) than in the prophylactic antibiotic group (75%). CONCLUSIONS: IRR sites and the sites of photon defects on DMSA renal scans showed a high correspondence, and these sites tended to progress to renal scarring. We suggest that VUR with IRR should be actively managed to decrease the chances of renal scarringope

    Patterned Si thin film electrodes for enhancing structural stability

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    A patterned film (electrode) with lozenge-shaped Si tiles could be successfully fabricated by masking with an expanded metal foil during film deposition. Its electrochemical properties and structural stability during the charge-discharge process were examined and compared with those of a continuous (conventional) film electrode. The patterned electrode exhibited a remarkably improved cycleability (75% capacity retention after 120 cycles) and an enhanced structural stability compared to the continuous electrode. The good electrochemical performance of the patterned electrode was attributed to the space between Si tiles that acted as a buffer against the volume change of the Si electrode

    Diffusion Decay Coefficient for Chloride Ions of Concrete Containing Mineral Admixtures

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    The diffusion coefficient for chloride ions and the diffusion decay coefficient for chloride ions are essential variables for a service life evaluation of concrete structures. They are influenced by water-binder ratio, exposure condition, curing temperature, cement type, and the type and use of mineral admixture. Mineral admixtures such as ground granulated blast furnace slag, fly ash, and silica fume have been increasingly used to improve resistance against chloride ions penetration in concrete structures built in an offshore environment. However, there is not enough measured data to identify the statistical properties of diffusion decay coefficient for chloride ions in concrete using mineral admixtures. This paper is aimed at evaluating the diffusion decay coefficient for chloride ions of concrete using ordinary Portland cement or blended cement. NT BUILD 492 method, an electrophoresis experiment, was used to measure the diffusion coefficient for chloride ions with ages. It was revealed from the test results that the diffusion decay coefficient for chloride ions was significantly influenced by W/B and the replacement ratio of mineral admixtures

    Synergistic use of hyperspectral uv-visible omi and broadband meteorological imager modis data for a merged aerosol product

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    The retrieval of optimal aerosol datasets by the synergistic use of hyperspectral ultraviolet (UV)-visible and broadband meteorological imager (MI) techniques was investigated. The Aura Ozone Monitoring Instrument (OMI) Level 1B (L1B) was used as a proxy for hyperspectral UV-visible instrument data to which the Geostationary Environment Monitoring Spectrometer (GEMS) aerosol algorithm was applied. Moderate-Resolution Imaging Spectroradiometer (MODIS) L1B and dark target aerosol Level 2 (L2) data were used with a broadband MI to take advantage of the consistent time gap between the MODIS and the OMI. First, the use of cloud mask information from the MI infrared (IR) channel was tested for synergy. High-spatial-resolution and IR channels of the MI helped mask cirrus and sub-pixel cloud contamination of GEMS aerosol, as clearly seen in aerosol optical depth (AOD) validation with Aerosol Robotic Network (AERONET) data. Second, dust aerosols were distinguished in the GEMS aerosol-type classification algorithm by calculating the total dust confidence index (TDCI) from MODIS L1B IR channels. Statistical analysis indicates that the Probability of Correct Detection (POCD) between the forward and inversion aerosol dust models (DS) was increased from 72% to 94% by use of the TDCI for GEMS aerosol-type classification, and updated aerosol types were then applied to the GEMS algorithm. Use of the TDCI for DS type classification in the GEMS retrieval procedure gave improved single-scattering albedo (SSA) values for absorbing fine pollution particles (BC) and DS aerosols. Aerosol layer height (ALH) retrieved from GEMS was compared with Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data, which provides high-resolution vertical aerosol profile information. The CALIOP ALH was calculated from total attenuated backscatter data at 1064 nm, which is identical to the definition of GEMS ALH. Application of the TDCI value reduced the median bias of GEMS ALH data slightly. The GEMS ALH bias approximates zero, especially for GEMS AOD values of >similar to 0.4 and GEMS SSA values of <similar to 0.95. Finally, the AOD products from the GEMS algorithm and MI were used in aerosol merging with the maximum-likelihood estimation method, based on a weighting factor derived from the standard deviation of the original AOD products. With the advantage of the UV-visible channel in retrieving aerosol properties over bright surfaces, the combined AOD products demonstrated better spatial data availability than the original AOD products, with comparable accuracy. Furthermore, pixel-level error analysis of GEMS AOD data indicates improvement through MI synergy

    Chiral Metafilms and Surface Enhanced Raman Scattering For Enantiomeric Discrimination of Helicoid Nanoparticles

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    Chiral nanophotonic platforms provide a means of creating near fields with both enhanced asymmetric properties and intensities. They can be exploited for optical measurements that allow enantiomeric discrimination at detection levels greater than 6 orders of magnitude than is achieved with conventional chirally sensitive spectroscopic methods based on circularly polarized light. The optimal approach for exploiting nanophotonic platforms for chiral detection would be to use spectroscopic methods that provide a local probe of changes in the near field environment induced by the presence of chiral species. Here we show that surface enhanced Raman spectroscopy (SERS) is such a local probe of the near field environment. We have used it to achieve enantiomeric discrimination of chiral helicoid nanoparticles deposited on left and right-handed enantiomorphs of a chiral metafilm. Hotter electromagnetic hotspots are created for matched combinations of helicoid and metafilms (left-left and right-right), while mismatched combinations leads to significantly cooler electromagnetic hotspots. This large enantiomeric dependency on hotspot intensity is readily detected using SERS with the aid of an achiral Raman reporter molecule. In effect we have used SERS to distinguish between the different EM environments of the plasmonic diastereomers produced by mixing chiral nanoparticles and metafilms. The work demonstrates that by combining chiral nanophotonic platforms with established SERS strategies new avenues in ultrasensitive chiral detection can be opened

    Chirality control of inorganic materials and metals by peptides or amino acids

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    Chirality exists everywhere in nature and may be one of the most important features in biological systems. The chirality of amino acid molecules is transferred to the peptide sequences, determining the secondary and further three-dimensional structures. As a result, even the macroscopic chirality observed in many living features can be controlled by the peptide sequence. Interestingly, recent studies have shown that achiral inorganic materials and metals, according to the crystallographic point group, can develop chiral morphologies that are precisely controlled by the amino acids and peptides. As a result, strong chiral optical responses can be generated even at visible wavelengths. In this review, we have highlighted recent pioneering examples to show the enantioselective interactions between inorganic materials/metals and amino acids/peptides and discussed the underlying mechanisms.Y

    Rapid Hepatobiliary Excretion of Micelle-Encapsulated/Radiolabeled Upconverting Nanoparticles as an Integrated Form

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    In the field of nanomedicine, long term accumulation of nanoparticles (NPs) in the mononuclear phagocyte system (MPS) such as liver is the major hurdle in clinical translation. On the other hand, NPs could be excreted via hepatobiliary excretion pathway without overt tissue toxicity. Therefore, it is critical to develop NPs that show favorable excretion property. Herein, we demonstrated that micelle encapsulated Cu-64-labeled upconverting nanoparticles (micelle encapsulated Cu-64-NOTA-UCNPs) showed substantial hepatobiliary excretion by in vivo positron emission tomography (PET) and also upconversion luminescence imaging (ULI). Ex vivo biodistribution study reinforced the imaging results by showing clearance of 84% of initial hepatic uptake in 72 hours. Hepatobiliary excretion of the UCNPs was also verified by transmission electron microscopy (TEM) examination. Micelle encapsulated Cu-64-NOTA-UCNPs could be an optimal bimodal imaging agent owing to quantifiability of Cu-64, ability of in vivo/ex vivo ULI and good hepatobiliary excretion property.
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