ARTICLE | doi:10.20944/preprints201806.0257.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: impervious surface mapping; multi-temporal data; change detection; high-resolution imagery; LiDAR; object-based post-classification fusion
Online: 15 June 2018 (14:32:50 CEST)
Impervious surface mapping with high-resolution remote sensing imagery has attracted increasing interest as it can provide detailed information for urban structure and distribution. Previous studies have suggested that the combination of LiDAR data and high-resolution imagery for impervious surface mapping performs better than using only high-resolution imagery. However, due to the high cost of the acquisition of LiDAR data, it is difficult to obtain the multi-sensor remote sensing data acquired at the same acquisition time for impervious surface mapping. Consequently, real landscape changes between multi-sensor remote sensing data at different acquisition times would lead to the error of misclassification in impervious surface mapping. This issue has mostly been neglected in previous works. Furthermore, the observation differences generated from multi-sensor data, including the problems of misregistration, missing data in LiDAR data, and shadow in high-resolution images would also challenge the final mapping result in the fusion of LiDAR data and high-resolution images. In order to conquer these problems, we propose an improved impervious surface mapping method incorporating both LiDAR data and high-resolution imagery at different acquisition times in consideration of real landscape changes and observation differences. In the proposed method, a multi-sensor change detection by supervised multivariate alteration detection is employed to obtain changed areas and misregistration areas. The no-data areas in the LiDAR data and the shadow areas in the high-resolution imagery are extracted by independent classification yielded by its corresponding single sensor data. Finally, an object-based post-classification fusion is proposed to take advantage of independent classification results with single-sensor data and the joint classification result with stacked multi-sensor data. Experiments covering the study site in Buffalo, NY, USA demonstrate that our method can accurately detect landscape changes and obviously improve the performance of impervious surface mapping.
REVIEW | doi:10.20944/preprints202104.0416.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Aminoglycosides, population pharmacokinetic modeling, intensive care unit, critically ill
Online: 15 April 2021 (13:10:47 CEST)
Background Although aminoglycosides are often used as treatment for Gram-Negative infections, optimal dosing regimens remains unclear, especially in ICU patients. This is due to a large between- and within-subject variability in the aminoglycosides’ pharmacokinetics in this population. Objective The review provides comprehensive data on the pharmacokinetics of aminoglycosides in patients hospitalized in ICU by summarizing all published PopPK models in ICU patients for amikacin, gentamicin, and tobramycin. The objective was to determine the presence of a consensus on the structural model used, significant covariates included, and therapeutic targets considered during dosing regimen simulations. Methods A literature search was conducted from the Medline/PubMed database, using the terms: ‘amikacin’, ’gentamicin’, ’tobramycin’, ‘pharmacokinetic(s)’, nonlinear mixed effect’, population’, ‘intensive care’ and ‘critically ill’. Results Nineteen articles were retained where amikacin, gentamicin and tobramycin pharmacokinetics were described in six, eleven and five models, respectively. Two-compartment model best described amikacin and tobramycin pharmacokinetics, whereas one-compartment model majorly described gentamicin pharmacokinetics. The most recurrent significant covariates were renal clearance and bodyweight. Across all aminoglycosides, mean interindividual variability in clearance and volume of distribution were 41.6% and 22.0%, respectively. A common consensus for an optimal dosing regimen for each aminoglycoside was not reached. Conclusion This review showed models developed for amikacin, from 2015 until now and for gentamicin and tobramycin from the past decades. Despite growing challenges of external evaluation, the latter should be more considered during model development. Further research including new covariates, additional simulated dosing regimens and external validation should be considered to better understand aminoglycosides pharmacokinetics in ICU patients.
ARTICLE | doi:10.20944/preprints202303.0321.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Rb/Sr ratios; Weathering intensity; Decadal timescales; Chaonaqiu Lake.
Online: 17 March 2023 (09:56:49 CET)
The Rb/Sr ratio of lake sediments has been widely adopted as an indicator of weathering intensity in studies of past climate change, but the geochemical significance of this ratio varies with timescale. Here we present Rb/Sr data for the last 300 years for sediments collected from Chaonaqiu Lake in the Liupan Mountains of the western Chinese Loess Plateau as a decadal-scale record of weathering intensity. To validate the application of this weathering proxy, we correlated the record with those of other major elements, rock-forming minerals, and paleoclimatic proxies. We found that Rb/Sr ratios are influenced mainly by Sr activity within the lake catchment (where Sr is likely sourced from albite). In addition, higher (lower) Rb/Sr ratios of bulk sediments from Chaonaqiu Lake are correlated with lower (higher) fractions of terrigenous detritus (SiO2, Ti, K2O, Al2O3, and Na2O). Lake bulk sediment Rb/Sr ratios are dominated by the input of terrigenous detritus over decadal timescales. Our data show that physical and chemical weathering in Chaonaqiu Lake catchment have opposing influences on bulk sediment Rb/Sr ratios, competing to dominate these ratios of lake sediments over different timescales, with ratios reflecting the relative importance of the two types of weathering. We infer that the Rb/Sr ratios of Chaonaqiu Lake sediments reflect climatic signals of precipitation and temperature over long timescales and of precipitation over short timescales.