3,736 research outputs found

    High resolution agriculture land cover using aerial digital photography and GIS : a case study for small island states

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    Chapter 7With the advent of site-specific crop management, sustainability and profitability, land farming now requires information and technology-based management system to identify, analyse and manage spatial and temporal resource variability. Th is approach is being made increasingly possible by recent innovation in information technologies such as mobile devices, geographic information systems, positioning technologies (such as Geographical Position system), and Earth Observations. Such innovation now off ers a holistic approach to micro-manage agricultural resources. (Robert et al., 1994). Basic mapping and farm-level record keeping is one of the first precision agriculture practices that must be implemented in a typical productive agriculture operation (Stombaugh et al., 2001). Typical tasks include mapping of variations that occur in largescale field features such as vegetation stress, crop rotation, inventorying, irrigation, soil drainage and erosion, pest control, etc. Th e search for a low cost methodology that takes into account the growth of information technology in data capture and surveying, data processing, database creation and geographic information systems becomes mandatory in order to respond to such needs. Th e study constitutes, for the first time in Malta, the collection of high precision farming statistics that makes use of an inexpensive system for aerial mapping that requires minimal ground truthing. Th e effectiveness of such a method for small areas was later demonstrated by Galdies and Borg (2006) related to coastal and beach management in the Maltese islands. In the current case, digital aerial remote sensing enabled the accurate mapping of agricultural variables, and coupled with ground survey data, resulted in the production of precise, high resolution agricultural crop-cover maps. Additional information can be further derived from this data that can be used for the optimisation of micro agriculture practices.peer-reviewe

    Between a rock and a hard place : site selection for Brush-tailed Rock-wallaby (Petrogale penicillata) translocations using an explicit decision-making process

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    Translocation programs are used in species conservation, but their success rates, particularly in Australia, are low. The poor outcomes for translocation programs are commonly attributed to a lack of information about habitat requirements, especially for rare and endangered species. To address this, the identification of suitable release sites using analytical methods such as Habitat Suitability Models (HSM), has become common. Since biodiversity losses are predicted to increase in the future, effective strategies to reduce species decline are required. Evidence-based decisions and scientific data to support conservation decision-making is paramount in conservation efforts. Once widely distributed across the mountainous country of south-eastern Australia, the distribution of the Brush-tailed Rock-wallaby (BTRW) has contracted particularly within the southern extent of their range. Considered critically endangered in Victoria and extinct in the Australian Capital Territory (ACT), it is more important than ever that the habitat requirements of the BTRW are understood to inform future translocations and the protection of this species in the wild. In this study, an explicit decision-making process was combined with Habitat Suitability Modelling (HSM) and ground-truthing methods to inform potential Brush-tailed Rock-wallaby (BTRW) translocations sites within Victoria and the ACT. Although this study is not the first of its kind to use HSM to predict BTRW habitat suitability, it is the first of its kind to apply an explicit decision-making process at two key stages: 1. to inform the selection of key physical and management attributes to be used in a HSM; and 2. to prioritise sites, within experts’ local knowledge areas, for ground-truthing By combining HSM and an explicit decision-making process, this study has been able to identify six suitable and two highly suitable habitat for BTRW across Victoria and the ACT. The use of an explicit decision-making process and ground-truthing methods to validate the model outputs and prioritise sites for ground-truthing has ensured that the final ranking of potential candidate sites can be reliably used by the Southern Brush-tailed Rock-wallaby Recovery Team to inform future translocations.Masters by Researc

    First High‐Resolution Benthic Habitat Map From the Greenland Shelf (Disko Bay Pilot Study)

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    A healthy ocean where marine habitats and ecosystems are mapped and protected is one of the UN's Sustainable Development Goals to sustainably use marine resources. Our study presents the first high-resolution benthic habitat map from Greenland integrating analyses of multibeam bathymetry and backscatter data, and ground-truth data including video sled, drop camera and day grab. The pilot area of 30 × 20 km is located on the continental shelf in central Disko Bay, West Greenland and all data were collected in a single, 10-day survey. Multibeam bathymetry data were gridded to a 10 × 10 m resolution, whereas backscatter mosaic was built from a 1 × 1 m grid cell to obtain higher resolution manifestation of seafloor properties. Ground-truth data consisted of 14 video transects, 17 drop camera deployments, and 17 sediment samples. Our results were verified with the published shallow seismic and vibrocore data from the Disko Bay region to link the geological background with the sedimentary environment. We distinguished five physical habitats in the area, based on the distribution of sediment types, water depth with general water masses and morphology. In addition, numerous gas seeps alongside pockmarks were observed in the area, as well as recent iceberg ploughmarks. The identified habitats were associated with two basic communities of benthic fauna, linked primarily to the distribution of sediments and representing hard bottom habitats (sessile fauna) and soft bottom habitats (shrimp/polychaetes). Our study is the first step toward mapping the entire seafloor of Disko Bay to provide a scientific context for the management of seafloor and marine resources

    Step by step: reconstruction of terrestrial animal movement paths by dead-reckoning

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    Background: Research on wild animal ecology is increasingly employing GPS telemetry in order to determine animal movement. However, GPS systems record position intermittently, providing no information on latent position or track tortuosity. High frequency GPS have high power requirements, which necessitates large batteries (often effectively precluding their use on small animals) or reduced deployment duration. Dead-reckoning is an alternative approach which has the potential to ‘fill in the gaps’ between less resolute forms of telemetry without incurring the power costs. However, although this method has been used in aquatic environments, no explicit demonstration of terrestrial dead-reckoning has been presented.Results: We perform a simple validation experiment to assess the rate of error accumulation in terrestrial dead-reckoning. In addition, examples of successful implementation of dead-reckoning are given using data from the domestic dog Canus lupus, horse Equus ferus, cow Bos taurus and wild badger Meles meles.Conclusions: This study documents how terrestrial dead-reckoning can be undertaken, describing derivation of heading from tri-axial accelerometer and tri-axial magnetometer data, correction for hard and soft iron distortions on the magnetometer output, and presenting a novel correction procedure to marry dead-reckoned paths to ground-truthed positions. This study is the first explicit demonstration of terrestrial dead-reckoning, which provides a workable method of deriving the paths of animals on a step-by-step scale. The wider implications of this method for the understanding of animal movement ecology are discussed

    A Framework for Assessing Impacts of Road Salt on Groundwater Supplies in Massachusetts

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    Nearly 500,000 tons of road salt are used each year on Massachusetts roadways. Runoff from these roads deposits salt in public groundwater sources, which poses human, environmental, and structural health risks. The goal of this project was to establish a framework that prioritizes opportunities to address risk-causing factors of salt contamination in groundwater drinking sources. We observed statewide trends in salt contamination, determined factors that contribute to salt contamination of groundwater, created a risk-assessment tool for use by municipalities, and drafted an informative fact sheet for public release. We also proposed recommendations to the MA Department of Environmental Protection for future work to identify and protect groundwater sources at risk of salt contamination

    BENTHIC HABITAT MAPPING OF MOUNTAIN TOP BANK WITHIN THE NORTHERN GULF OF MEXICO THROUGH INTEGRATED GEOPHYSICAL AND VISUAL DATA ANALYSIS

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    Mesophotic coral ecosystems (MCEs) are among the seafloor ecosystems that have been poorly studied throughout the world’s oceans, but they are a vital and diverse ecosystem that should be prioritized for future mapping and ecological studies. Priority should be given to them because they possess natural, social, and economic values, and face a variety of threats, all of which, if not better understood will result in the loss of this unique ecosystem. Insights into these ecosystems, among other deep-sea environments, are lacking due to difficulty accessing them, inherent lag between data collection by an autonomous system and observation by a scientific team, and the vastness of the seafloor. The Gulf of Mexico, a geologically complex environment, has demonstrated the characteristics needed to support MCEs, with reefs such as the Pinnacle Reefs, Flower Garden Banks National Marine Sanctuary (FGBNMS), the Florida Middle Ground reef system, and Pulley Ridge already identified. Mountain Top Bank (MTB), a hardground feature 60-150 m below the sea surface, is a mesophotic reef site off the coast of Mississippi, USA. As it is poorly understood, it is the focus of this study. Bathymetry, backscatter, and photographic ground truthing data were collected by autonomous surface and underwater vehicles (ASV, AUV) and compiled into ArcGIS software to produce a benthic habitat map (BHM) and geodatabase of this site. These data were used to correlate fish and macroinvertebrate presence and abundance with habitat features within a transect atop MTB. This analysis illustrated that the site is characterized by a network of outcrops and boulders interspersed within a predominately sandy environment, with a diverse array of biota including Cnidaria, Porifera, Mollusca, Chordata, Echinodermata, and Rhodophyta. Compiling these data into a BHM and geographic information system (GIS) geodatabase is a powerful way to assess ecosystems and support conservation efforts

    Tiger sharks support the characterization of the world’s largest seagrass ecosystem

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    Seagrass conservation is critical formitigating climate change due to the large stocks of carbon they sequester in the seafloor. However, effective conservation and its potential to provide nature-based solutions to climate change is hindered by major uncertainties regarding seagrass extent and distribution. Here, we describe the characterization of the world’s largest seagrass ecosystem, located in The Bahamas. We integrate existing spatial estimates with an updated empirical remote sensing product and perform extensive groundtruthing of seafloor with 2,542 diver surveys across remote sensing tiles. We also leverage seafloor assessments and movement data obtained from instrument-equipped tiger sharks, which have strong fidelity to seagrass ecosystems, to augment and further validate predictions. We report a consensus area of at least 66,000 km2 and up to 92,000km2 of seagrass habitat across The Bahamas Banks. Sediment core analysis of stored organic carbon further confirmed the global relevance of the blue carbon stock in this ecosystem. Data from tiger sharks proved important in supporting mapping and groundtruthing remote sensing estimates. This work provides evidence of major knowledge gaps in the ocean ecosystem, the benefits in partnering with marine animals to address these gaps, and underscores support for rapid protection of oceanic carbon sinks.Beneath The WavesDisney Conservation FundBarry and Mimi Sternlicht FoundationSant FamilyPictet FoundationPacific Treasure FoundationKing FamilyD. and J. Harris, B. Coughlin and FamilyP. Nicholson and WCPD FoundationSouthern TideHillsdaleThayer AcademyDiscovery CommunicationsMary O'Malley and Lupo Dion TrustNational Geographic SocietyJ. Lake and JDL, Inc.Towle Family Ocean FoundationKaro Family TrustScience Foundation Ireland 18/SIRG/5549King Abdullah University of Science & Technology36Pi

    Investigations Into the Application of Single-Beam Acoustic Backscatter for Describing Shallow Water Marine Habitats

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    Chapter 1 Producing thematic coral reef benthic habitat maps from single-beam acoustic backscatter has been hindered by uncertainties in interpreting the acoustic energy parameters E1 (~roughness) and E2 (~hardness), typically limiting such maps to sediment classification schemes. In this study acoustic interpretation was guided by high-resolution LIDAR (Light Detection And Ranging) bathymetry. Each acoustic record, acquired from a BioSonics DT-X echosounder and multiplexed 38 and 418 kHz transducers, was paired with a spatially-coincident value of a LIDAR-derived proxy for topographic complexity (Reef-Volume) and its membership to one of eight LIDAR-delineated benthic habitat classes. The discriminatory capabilities of the 38 and 418 kHz signals were generally similar. Individually, the E1 and E2 parameters of both frequencies differentiated between levels of LIDAR Reef-Volume and most benthic habitat classes, but could not unambiguously delineate benthic habitats. Plotted in E1:E2 Cartesian space, both frequencies formed two main groupings: uncolonized sand habitats and colonized reefal habitats. E1 and E2 were significantly correlated at both frequencies; positively over the sand habitats and negatively over the reefal habitats, where the scattering influence of epibenthic biota strengthened the E1:E2 interdependence. However, sufficient independence existed between E1 and E2 to clearly delineate habitats using the multi-echo E1/E2 Bottom Ratio method. The point-by-point calibration provided by the LIDAR data was essential for resolving the uncertainties surrounding the factors informing the acoustic parameters in a large, survey-scale dataset. The findings of this study indicate that properly interpreted single-beam acoustic data can be used to thematically categorize coral reef benthic habitats. Chapter 2 A large-scale acoustic survey was conducted in Apr-May 2008, with the objective of quantifying the abundance and distribution of seasonal drift macroalgae (DMA) in the Indian River Lagoon. Indian River was surveyed from the Sebastian Inlet to its northernmost extent in the Titusville area. Banana River was surveyed from its convergence with the Indian River northward to the Federal Manatee Zone near Cape Canaveral. The survey vessel was navigated along pre-planned lines running east-west and spaced 200 m apart. The river edges were surveyed to a minimum depth of approximately 1.3 m. Hydroacoustic data were collected with a BioSonics DT-X echosounder and two multi-plexed digital transducers operating at 38 and 418 kHz. The 38 and 418 kHz hydroacoustic data were processed with BioSonics Visual Bottom Typer (VBT) seabed classification software to obtain values of E1’ (time integral of the squared amplitude of the 1st part of the 1st echo waveform), E1 (2nd part of 1st echo), E2 (complete 2nd echo), and FD (fractal dimension characterizing the shape of the 1st echo). Following quality analysis, a training dataset was compiled from 131 hydroacoustic + video samples collected across the extent of the study area. The 38 and 418 kHz E1’, E1, E2, and FD datasets were merged and submitted to a series of three discriminant analyses (DA) to refine the training samples into three pure end-member categories; bare substrate, short SAV (typically Caluerpa prolifera, ~10cm or less), and DMA. The Fisher’s linear discriminant functions from the third and final descriptive DA were used to classify each of the 480,000+ hydroacoustic survey records as either bare, short SAV, or DMA. The classified survey records were then used to calculate the biomass of DMA as the product of average DMA cover for a block of ten records times the wet weight of DMA. The DMA biomass was found to be 69,859 metric tons (wet weight) within the 293.1 km2 study area. The acoustically-predicted mean percent cover of DMA was (i) significantly greater within the navigation channels (18.3%) than outside (12.2%), and (ii) significantly greater in the Indian River (12.9%) than in the Banana River (9.3%). The overall predictive accuracy of total SAV (i.e. short SAV plus DMA) was 78.9% (n=246) at three levels of cover (0-33, 33-66, and 66-100%). The Tau coefficient, a measure of the improvement of the classification scheme over random assignment, was 0.683 ± 0.076 (95% CI), i.e. the rate of misclassifications was 68.3% less than would be expected from random assignment of hydroacoustic records to total SAV cover. The incorporation of multi-plexed digital transducers in conjunction with new post-processing techniques realized the goal of establishing an accurate, efficient, and temporally consistent method for acoustically mapping DMA biomass. Chapter 3 This chapter presents the results of a large-scale hydroacoustic survey conducted in April-May 2008. The objective of this study was to map the distribution and vertical extent of muck in the Indian River Lagoon, utilizing the data collected during a seasonal drift macroalgae survey. Indian River was surveyed from the Sebastian Inlet to its northernmost extent in the Titusville area. Banana River was surveyed from its convergence with the Indian River northward to the Federal Manatee Zone near Cape Canaveral. The survey vessel was navigated along pre-planned lines running east-west and spaced 200 m apart, except for when muck was indicated by the oscilloscope display, at which point a meandering path was adopted to demarcate the horizontal extent of muck. Hydroacoustic data were collected with a BioSonics DT-X echosounder and two multi-plexed digital transducers operating at 38 and 420 kHz. The vertical extent of muck was derived from the 38 kHz hydroacoustic signal, which was processed with Visual Analyzer, a fish-finding software package produced by BioSonics Inc. The software was adapted to integrate echo energy below the water-sediment interface, and a set of post-processing algorithms were developed to translate the sub-bottom echo energy profile into continuous scale estimates of muck thickness. In this manner 500,000+ 38 kHz pings were translated into 88,927 geo-located estimates of muck layer thickness, down to a minimum bottom depth of 1 m. Ground-truthing was conducted in July 2008 at twenty sites within the Indian River. The predictions of muck layer thickness were found to be accurate over the ground-truthed range of 0-3m (r2 = 0.882, SE=0.52m). The vertical distribution of acoustically-predicted muck demonstrated the tendency for muck to accumulate in deeper areas of the lagoon. For the case of Indian River (excluding navigation channels), muck was not detected in depths shallower than 1.4m and rare in the range of 1.4-2.2 m (only 3.6% of records had a predicted muck thickness greater than 0.5 m). The frequency of muck plateaued between 2.2-3.4 m (9.6%) before making a sharp rise to 82% in the range of 4-5 m. As expected, the mean muck layer thickness was significantly greater within the navigation channels (0.56 m) than outside of them (0.08 m). A significant latitudinal trend of muck thickness was detected within the Indian River navigation channels. The mean muck thickness decreased from 1.38 m at its northernmost origins to 0.83 m in the Titusville area before plateauing at approximately 0.4 m for the remainder of segments. Outside of the main ICW channels, 23 individual muck deposits were identified; 22 in the Indian River and 1 in the Banana River. Factors in descending order of co-occurrence were proximity to causeways or jetties, riverbed depressions, and proximity to shore and drainage channels. In conclusion, this study establishes that a single-beam acoustic survey is a cost-effective and accurate alternative for mapping the distribution and vertical extent of muck deposits in the shallow-water environment of the Indian River Lagoon. Moreover, the temporal consistency afforded by a digital transducer allows for direct and meaningful comparisons between successive surveys. Chapter 4 A thematic map of benthic habitat was produced for a coral reef in the Republic of Palau, utilizing hydroacoustic data acquired with a BioSonics DT-X echosounder and a single-beam 418 kHz digital transducer. This paper describes and assesses a supervised classification scheme that used a series of three discriminant analyses (DA) to refine training samples into end-member structural and biological elements, utilizing E1â€Č (leading edge of 1st echo), E1 (trailing edge of 1st echo), E2 (complete 2nd echo), fractal dimension (1st echo shape), and depth as predictor variables. Hydroacoustic training samples were assigned to one of six predefined groups based on the plurality of benthic elements (sand, sparse SAV, rubble, pavement, rugose hardbottom, branching coral), visually estimated from spatially co-located ground-truthing videos. Records that classified incorrectly or failed to exceed a minimum probability of group membership were removed from the training dataset until only ‘pure’ end-member records remained. This refinement of ‘mixed’ training samples circumvented the dilemma typically imposed by the benthic heterogeneity of coral reefs, i.e. to either train the acoustic ground discrimination system (AGDS) on homogeneous benthos and leave the heterogeneous benthos un-classified, or attempt to capture the many ‘mixed’ classes and overwhelm the discriminatory capability of the AGDS. This was made possible by a conjunction of narrow beamwidth (6.4o) and shallow depth (1.2 to 17.5 m), which produced a sonar footprint small enough to resolve most of the microscale features used to define benthic groups. Survey data classified from the 3rd-Pass training DA were found to (i) conform to visually-apparent contours of satellite imagery, (ii) agree with the structural and biological delineations of a benthic habitat map created from visual interpretation of 2004 IKONOS imagery, and (iii) yield values of benthic cover that agreed closely with independent, contemporaneous video transects. The methodology was proven on a coral reef environment for which high quality satellite imagery existed, as an example of the potential for single-beam systems to thematically map coral reefs in deep or turbid settings where optical methods are unsatisfactory. Chapter 5 Beginning In the winter of 2003-2004, several episodes of red drift macroalgae blooms resulted in massive amounts of macroalgae washing ashore the beaches of Sanibel Island, Bonita Springs, and Ft Meyer Florida. A study conducted after the first event supported a link to increasing land-based nutrient enrichment. A large-scale program was initiated in May 2008, with the primary goal of further defining the possible roles and sources of nutrient enrichment with respect to nuisance macroalgae blooms. This study reports the results of the hydroacoustic mapping component of this program. The goal of this study was to identify areas of substrate suitable for supporting a macroalgae bloom. Areas within San Carlos Bay and offshore Sanibel Island, FL were hydroacoustically surveyed from nearshore to about 11 km offshore during the periods of October 6-10, 2008 and May 10-22, 2009. The hydroacoustic data was acquired with a BioSonics DT-X echosounder and a multiplexed single-beam digital transducers operating at 38 and 418 kHz. Eleven acoustic parameters derived from the 38 and 418 kHz signals were utilized to classify the survey data into 5 ascending categories of visually-apparent seabed roughness. Classes 1 and 2 were both primarily constituted of unconsolidated silt and sand-sized sediments, unsuitable for a bloom. Class 3 is a marginal substrate for a bloom, consisting of packed sand and large intact shell debris. Classes 4 and 5 offer the best attachment sites for a bloom, consisting of consolidated shell hash, live hardbottom, and submerged aquatic vegetation. The majority (~ 80%) of acoustic classifications were of soft bottom sediments (classes 1-2), but there were two significant expanses of rough seabed suitable for macroalgae attachment. These two areas covered a total of 19 km2, within which ~ 56% of the hydroacoustic records classified as “rough” (classes 3-5). The first was a large area of seagrass beds and live hardbottom in the mouth of San Carlos Bay, where large amounts of macroalgae were variably present during the April-May 2009 surveys. The second was offshore Lighthouse Point, near the mouth of San Carlos Bay, situated near a large sand spit that extended from the beach to approximately 6 km offshore. Along the west side of the sand spit there were substantial areas of moderate to high bottom roughness, mostly in the form of consolidated shell hash. The average depths of these two acoustically-rough areas were only 5.0 and 4.0 m, so sufficient irradiance to initiate a bloom could be assumed. These textured and shallow areas on or near the mouth of San Carlos Bay are presumably potential sources for macroalgae attachment and growth, which could easily be transported onto the beaches under some storm conditions given the close proximity to the shoreline. In contrast, the areas in open Gulf of Mexico waters were classified predominantly as soft sediments with low bottom roughness. The site offshore Redfish Pass had a moderate (~22%) proportion of “rough” classifications out to 5km offshore, but from 5-10km offshore the bottom classified as \u3e95% soft sediments. The other two Gulf of Mexico sites classified as \u3e95% soft sediments from nearshore to 11 km offshore. Independent, concurrent video transects indicated there were small areas with large amounts of shell and live hard bottom that occurred sporadically greater than 10km offshore, but all things considered the open Gulf waters around Sanibel Island may not be a major source of drift macroalgae. Chapter 6 This study presents the results of methods developed for acoustic remote sensing of Acropora cervicornis, a threatened species of scleractinian sporadically occurring on the nearshore hardbottom of Southeast Florida. The objective was to develop techniques for mapping isolated Acropora patches on a scale larger than what is feasible using on-the-ground methods. A time-series of A. cervicornis cover could inform resource managers about the fate of such patches, e.g. do they appear and vanish, creep by extension from a central point, or leap by colony fragmentation. The main challenge to acoustically mapping A. cervicornis was distinguishing it from gorgonians occupying the same habitat. Hydroacoustic surveys were conducted in October 2009 at two nearshore sites in Broward County, FL utilizing a BioSonics DT-X echosounder and multiplexed single-beam digital transducers operating at frequencies of 38 and 418 kHz. NCRI scientists have monitored the spatial extent and percent cover of A. cervicornis within these sites, providing an ideal background against which to calibrate the hydroacoustic predictions. Two approaches were evaluated. The first approach utilized BioSonics EcoSAV post-processing software, designed to predict areal cover and canopy height of submerged aquatic vegetation using a series of heuristic pattern-recognition algorithms. Anchored over A. cervicornis, the 38 and 418 kHz signals performed similarly well. Anchored over gorgonians, the 38 kHz signal detected the canopy roughly half as frequently as the 418 kHz signal. Undifferentiated 418 kHz EcoSAV cover was allocated to either A. cervicornis or gorgonians exploiting this frequency-dependent detection. The second approach utilized the acoustic energy (E0, E1â€Č, E1, and E2) and shape (fractal dimension) parameters obtained from BioSonics Visual Bottom Typer software. A dual-frequency training dataset was used to classify records as sand, bare pavement, gorgonians, or A. cervicornis. Both approaches yielded promising results, based on a number of metrics, unambiguously demonstrating that single-beam AGDS are capable of reliably detecting A. cervicornis and gorgonians under controlled conditions
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