Search results for "910"
showing 10 items of 139 documents
Using machine learning on tree-ring data to determine the geographical provenance of historical construction timbers
2023
Funder: Bavarian Climate Research Network (BayKliF)
The Developmental Contribution From Mobile Phones Across the Agricultural Value Chain in Rural Africa
2011
Published version of an article from the journal: The Electronic Journal of Information Systems in Developing Countries. Also available fro the publisher: http://www.ejisdc.org/Ojs2/index.php/ejisdc/article/viewFile/849/377 The most widespread information and communication technology (ICT) in developing countries today is the mobile phone. The majority of people in the least developed countries still live in rural areas and their livelihood depends on the primary industries. This study investigates the use of mobile phones among farmers in rural Tanzania in order to supply empirical data on the developmental role of this technology. The results show that the improved access to communication…
Suture Materials: Do They Affect Fistula and Stricture Rates in Flap Urethroplasties?
2003
<i>Introduction:</i> The effect of suture materials on urethroplasty complications is debated. Indeed, materials with a delayed absorption might either reduce the incidence of fistulas by ensuring a prolonged approximation of neo-urethral edges or increase the risk of urethral strictures due to a prolonged tissue reaction during suture absorption. We retrospectively evaluated the role of suture materials in the complication rate of urethroplasty procedures performed in our institution over a 10-year period. <i>Patients and Methods:</i> Three hundred and thirty-six boys undergoing a flap procedure (parameatal based, preputial tube, or onlay preputial flap) for hypospa…
Atmospheric correction of ENVISAT/MERIS data over inland waters: Validation for European lakes
2010
Traditional methods for aerosol retrieval and atmospheric correction of remote sensing data over water surfaces are based on the assumption of zero water reflectance in the near-infrared. Another type of approach which is becoming very popular in atmospheric correction over water is based on the simultaneous retrieval of atmospheric and water parameters through the inversion of coupled atmospheric and bio-optical water models. Both types of approaches may lead to substantial errors over optically-complex water bodies, such as case II waters, in which a wide range of temporal and spatial variations in the concentration of water constituents is expected. This causes the water reflectance in t…
Monitoring and prediction in early warning systems for rapid mass movements
2015
Rapid mass movements (RMM) pose a substantial risk to people and infrastructure. Reliable and cost-efficient measures have to be taken to reduce this risk. One of these measures includes establishing and advancing the state of practice in the application of early warning systems (EWSs). EWSs have been developed during the past decades and are rapidly increasing. In this paper, we focus on the technical part of EWSs, i.e., the prediction and timely recognition of imminent hazards, as well as on monitoring slopes at risk and released mass movements. Recent innovations in assessing spatial precipitation, monitoring and precursors of the triggering and deformation of RMM offer new opportunities…
Soil erosion modelling: a global review and statistical analysis
2021
40 Pags.- 10 Figs.- 2 Tabls.- Suppl. Informat. The definitive version is available at: https://www.sciencedirect.com/science/journal/00489697
Seasonal Changes in Urban PM2.5 Hotspots and Sources from Low-Cost Sensors
2022
PM2.5 concentrations in urban areas are highly variable, both spatially and seasonally. To assess these patterns and the underlying sources, we conducted PM2.5 exposure measurements at the adult breath level (1.6 m) along three ~5 km routes in urban districts of Mainz (Germany) using portable low-cost Alphasense OPC-N3 sensors. The survey took place on five consecutive days including four runs each day (38 in total) in September 2020 and March 2021. While the between-sensor accuracy was tested to be good (R² = 0.98), the recorded PM2.5 values underestimated the official measurement station data by up to 25 µg/m3. The collected data showed no consistent PM2.5 hotspots between September and M…
Sun-induced chlorophyll fluorescence II: Review of passive measurement setups, protocols, and their application at the leaf to canopy level
2019
Imaging and non-imaging spectroscopy employed in the field and from aircraft is frequently used to assess biochemical, structural, and functional plant traits, as well as their dynamics in an environmental matrix. With the increasing availability of high-resolution spectroradiometers, it has become feasible to measure fine spectral features, such as those needed to estimate sun-induced chlorophyll fluorescence (F), which is a signal related to the photosynthetic process of plants. The measurement of F requires highly accurate and precise radiance measurements in combination with very sophisticated measurement protocols. Additionally, because F has a highly dynamic nature (compared with othe…
Trends in phenological parameters and relationship between land surface phenology and climate data in the Hyrcanian forests of Iran
2017
Vegetation activity may be changed in response to climate variability by affecting seasonality and phenological events. Monitoring of land surface phenological changes play a key role in understanding feedback of ecosystem dynamics. This study focuses on the analysis of trends in land surface phenology derived parameters using normalized difference vegetation index time series based on Global Inventory Monitoring and Mapping Studies data in the Hyrcanian forests of Iran covering the period 1981–2012. First, we applied interpolation for data reconstruction in order to remove outliers and cloud contamination in time series. Phenological parameters were retrieved by using the midpoint approach…
Variability and Uncertainty Challenges in Scaling Imaging Spectroscopy Retrievals and Validations from Leaves Up to Vegetation Canopies
2019
Imaging spectroscopy of vegetation requires methods for scaling and generalizing optical signals that are reflected, transmitted and emitted in the solar wavelength domain from single leaves and observed at the level of canopies by proximal sensing, airborne and satellite spectroradiometers. The upscaling embedded in imaging spectroscopy retrievals and validations of plant biochemical and structural traits is challenged by natural variability and measurement uncertainties. Sources of the leaf-to-canopy upscaling variability and uncertainties are reviewed with respect to: (1) implementation of retrieval algorithms and (2) their parameterization and validation of quantitative products through…