415 research outputs found

    Remote Sensing Approaches and Related Techniques to Map and Study Landslides

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    Landslide is one of the costliest and fatal geological hazards, threatening and influencing the socioeconomic conditions in many countries globally. Remote sensing approaches are widely used in landslide studies. Landslide threats can also be investigated through slope stability model, susceptibility mapping, hazard assessment, risk analysis, and other methods. Although it is possible to conduct landslide studies using in-situ observation, it is time-consuming, expensive, and sometimes challenging to collect data at inaccessible terrains. Remote sensing data can be used in landslide monitoring, mapping, hazard prediction and assessment, and other investigations. The primary goal of this chapter is to review the existing remote sensing approaches and techniques used to study landslides and explore the possibilities of potential remote sensing tools that can effectively be used in landslide studies in the future. This chapter also provides critical and comprehensive reviews of landslide studies focusÂŹing on the role played by remote sensing data and approaches in landslide hazard assessment. Further, the reviews discuss the application of remotely sensed products for landslide detection, mapping, prediction, and evaluation around the world. This systematic review may contribute to better understanding the extensive use of remotely sensed data and spatial analysis techniques to conduct landslide studies at a range of scales

    Modeling Antecedent Soil Moisture to Constrain Rainfall Thresholds for Shallow Landslides Occurrence

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    Rainfall-triggered shallow landslide events have caused losses of human lives and millions of euros in damage to property in all parts of the world. The need to prevent such hazards combined with the difficulty of describing the geomorphological processes over regional scales led to the adoption of empirical rainfall thresholds derived from records of rainfall events triggering landslides. These rainfall intensity thresholds are generally computed, assuming that all events are not influenced by antecedent soil moisture conditions. Nevertheless, it is expected that antecedent soil moisture conditions may provide critical support for the correct definition of the triggering conditions. Therefore, we explored the role of antecedent soil moisture on critical rainfall intensity-duration thresholds to evaluate the possibility of modifying or improving traditional approaches. The study was carried out using 326 landslide events that occurred in the last 18 years in the Basilicata region (southern Italy). Besides the ordinary data (i.e., rainstorm intensity and duration), we also derived the antecedent soil moisture conditions using a parsimonious hydrological model. These data have been used to derive the rainfall intensity thresholds conditional on the antecedent saturation of soil quantifying the impact of such parameters on rainfall thresholds

    Toward Cleaner Production : Can Mobile Phone Technology Help Reduce Inorganic Fertilizer Application? Evidence Using a National Level Dataset

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    Abstract: Increasing agricultural production and optimizing inorganic fertilizer (IF) use are imperative for agricultural and environmental sustainability. Mobile phone usage (MPU) has the potential to reduce IF application while ensuring environmental and agricultural sustainability goals. The main objectives of this study were to assess MPU, mobile phone promotion policy, and whether the mediation role of human capital can help reduce IF use. This study used baseline regression analysis and propensity score matching, difference-in-differences (PSM-DID) to assess the impact of MPU on IF usage. However, the two-stage instrumental variables method (IVM) was used to study the effects of mobile phone promotion policy on IF usage. This study used a national dataset from 7987 rural households in Afghanistan to investigate the impacts of MPU and associated promotion policies on IF application. The baseline regression outcomes showed that the MPU significantly reduced IF usage. The evaluation mechanism revealed that mobile phones help reduce IF application by improving the human capital of farmers. Besides, evidence from the DID technique showed that mobile phone promotion policies lowered IF application. These results remained robust after applying the PSM-DID method and two-stage IVM to control endogenous decisions of rural households. This study results imply that enhancing the accessibility of wideband in remote areas, promoting MPU, and increasing investment in information communication technologies (ICTs) infrastructure can help decrease the IF application in agriculture. Thus, the government should invest in remote areas to facilitate access to ICTs, such as having a telephone and access to a cellular and internet network to provide an environment and facility to apply IF effectively. Further, particular policy support must focus on how vulnerable populations access the internet and mobile phone technologies

    2. C. W. Holzwarth

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    Abstract: We have investigated the feasibility of multimode polysilicon waveguides to demonstrate the suitability of polysilicon as a candidate for multilayer photonic applications. Solid Phase Crystallization (SPC) with a maximum temperature of 1000°C is used to create polysilicon on thermally grown SiO 2 . We then measure the propagation losses for various waveguide widths on both polysilicon and crystalline silicon platforms. We find that as the width increases for polysilicon waveguides, the propagation loss decreases similar to crystalline silicon waveguides. At a waveguide width of 10”m, polysilicon and crystalline silicon waveguides have propagation losses of 0.56dB/cm and 0.31 dB/cm, respectively, indicating there is little bulk absorption from the polysilicon and is the lowest propagation loss for polysilicon demonstrated to date. In addition, the first 1x12 polysilicon MMI is demonstrated with a low insertion loss of −1.29dB and a high uniformity of 1.07dB. These results vindicate the use of polysilicon waveguides of varying widths in photonic integrated circuits

    Characterization of acaricide resistance in tick isolates collected from Rajasthan, India

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          Rhipicephalus (Boophilus) microplus and Hyalomma anatolicum are the most common tick species infesting milk and meat producing animals throughout the country. The present study was conducted to evaluate the acaricide resistance status of the tick species to deltamethrin, cypermethrin, diazinon collected from 10 districts of Rajasthan. Characterization of resistance was carried out by adult immersion test (AIT) and larval packet test (LPT). In case of (B.) microplus resistance to deltamethrin at level I (RF = 2.5 – 4.9) in 02 isolates, at level II in 03 isolates (RF = 5.4 – 11.5) and level IV in 02 isolates (RF = 48.1 – 95.7) was detected. The resistance to cypermethrin was detected in 08 isolates of which resistance at level I in 03 isolates (RF = 2.7 - 4.58) and at level II in 05 isolates (RF = 8.05 – 16.2). Diazinon resistance was detected at level II in 06 isolates (RF = 5.8 –22.8), at level III in 01 isolates (RF = 39.0) and level IV in 02 isolates (RF = 65.9 – 66.0). While in case of H. anatolicum, the resistance to deltamethrin at level I (RF = 1.79 –2.52) in 03 isolates, to cypermethrin in 03 isolates (RF= 2.0 - 3.95) and to diazinon at level I in 03 isolates (RF = 1.32 –2.18) out of eleven isolates was detected.         A significant correlation between esterase enzyme ratio and resistant factor of tick isolates was observed with correlation coefficient (r) in α- and ß-esterase activity. The coefficient of determination (R2) for α- and ß-esterase activity indicated that 55.9 and 50.5% data points of R.(B.) microplus isolates and 66.7 and 47.2% data points of H. anatolicum isolates were very close to the correlation lines.       Analysis of sequence data of 3 targeted positions of the sodium channel gene detected a cytosine (C) to adenine (A) nucleotide substitution (CTC to ATC) at position 190 in domain II S4–5 linker region of para-sodium channel gene in 3 isolates and in reference deltamethrin resistant IVRI-IV line.      The western dry region and central plateau hills region revealed higher density of resistant ticks where intensive crossbred cattle population are reared and synthetic pyrethroids and organophosphate compounds are commonly used. The data shows an urgent need of revisiting the tick control strategy implemented through concerned government/non-government agencies

    Bridge to the future: Important lessons from 20 years of ecosystem observations made by the OzFlux network

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    In 2020, the Australian and New Zealand flux research and monitoring network, OzFlux, celebrated its 20th anniversary by reflecting on the lessons learned through two decades of ecosystem studies on global change biology. OzFlux is a network not only for ecosystem researchers, but also for those ‘next users’ of the knowledge, information and data that such networks provide. Here, we focus on eight lessons across topics of climate change and variability, disturbance and resilience, drought and heat stress and synergies with remote sensing and modelling. In distilling the key lessons learned, we also identify where further research is needed to fill knowledge gaps and improve the utility and relevance of the outputs from OzFlux. Extreme climate variability across Australia and New Zealand (droughts and flooding rains) provides a natural laboratory for a global understanding of ecosystems in this time of accelerating climate change. As evidence of worsening global fire risk emerges, the natural ability of these ecosystems to recover from disturbances, such as fire and cyclones, provides lessons on adaptation and resilience to disturbance. Drought and heatwaves are common occurrences across large parts of the region and can tip an ecosystem's carbon budget from a net CO2 sink to a net CO2 source. Despite such responses to stress, ecosystems at OzFlux sites show their resilience to climate variability by rapidly pivoting back to a strong carbon sink upon the return of favourable conditions. Located in under-represented areas, OzFlux data have the potential for reducing uncertainties in global remote sensing products, and these data provide several opportunities to develop new theories and improve our ecosystem models. The accumulated impacts of these lessons over the last 20 years highlights the value of long-term flux observations for natural and managed systems. A future vision for OzFlux includes ongoing and newly developed synergies with ecophysiologists, ecologists, geologists, remote sensors and modellers.</p
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