Spatial Resolution Analysis Research Articles

Characterizing the complexity of microseismic signals at slow-moving clay-rich debris slides: the Super-Sauze (southeastern France) and Pechgraben (Upper Austria) case studies

Abstract. Soil and debris slides are prone to rapid and dramatic reactivation. Deformation within the instability is accommodated by sliding, whereby weak seismic energies are released through material deformation. Thus, passive microseismic monitoring provides information that relates to the slope dynamics. In this study, passive microseismic data acquired at Super-Sauze (southeastern France) and Pechgraben (Upper Austria) slow-moving clay-rich debris slides (“clayey landslides”) are investigated. Observations are benchmarked against previous similar case studies to provide a comprehensive and homogenized typology of microseismic signals at clayey landslides. A thorough knowledge of the various microseismic signals generated by slope deformation is crucial for the future development of automatic detection systems to be implemented in landslide early-warning systems. Detected signals range from short-duration (< 2 s) quake-like signals to a wide variety of longer-duration tremor-like radiations (> 2 s – several min). The complexity of seismic velocity structures, the low quantity and low quality of available signal onsets and non-optimal seismic network geometry severely impedes the source location procedure; thus, rendering source processes characterization challenging. Therefore, we constrain sources' locations using the prominent waveform amplitude attenuation pattern characteristic of near-source area (< about 50 m) landslide-induced microseismic events. A local magnitude scale for clayey landslides (ML−LS) is empirically calibrated using calibration shots and hammer blow data. The derived ML−LS returns daily landslide-induced microseismicity rates that positively correlate with higher average daily displacement rates. However, high temporal and spatial resolution analyses of the landslide dynamics and hydrology are required to better decipher the potential relations linking landslide-induced microseismic signals to landslide deformation.

The role of attention in remembering important item-location associations.

When encountering an excess of information, people are able to selectively remember high-value information by strategically allocating attention during the encoding period, termed value-directed remembering. This has been demonstrated in both the episodic verbal and visuospatial memory domains. Importantly, the allocation of attention also plays a crucial role in the binding of identity and location information in visuospatial memory. We examined how taxing attentional resources to various degrees during encoding might affect visuospatial memory and selectivity. Participants studied items paired with point values indicating their value in a grid display and were asked to maximize their point score (a summation of the points associated with correctly remembered information). Participants viewed items under either a sequential or simultaneous presentation format and in either the presence or absence of a secondary tone discrimination task. While participants in the divided attention conditions recalled fewer item-location associations overall, participants in all encoding conditions prioritized high-value information in memory, providing further evidence that selectivity can be maintained even when attentional resources are taxed. However, differences between presentation formats emerged when conducting spatial resolution analyses examining errors. Errors in the simultaneous conditions were only influenced by item value when attention was full during encoding, while errors in the sequential conditions were not influenced by item value, regardless of available attentional resources. The results suggest participants can strategically allocate attention during encoding even under cognitively-demanding conditions and that gist-based visuospatial memory may only be influenced by information importance when adequate attentional resources are available.

Ancient Microbial Activity in Deep Hydraulically Conductive Fracture Zones within the Forsmark Target Area for Geological Nuclear Waste Disposal, Sweden

Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of δ13Ccalcite (−36.2 to +20.2‰ V-PDB) and δ34Spyrite (−11.7 to +37.8‰ V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of δ18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.

Multi-decadal spatial and temporal changes of extreme precipitation patterns in northern China (Jing-Jin-Ji district, 1960–2013)

Observations of changes in daily extreme precipitation from local to global scales provide essential information for assessing the anthropogenic forcing driving natural climate. This study presents an analysis of daily precipitation records over the past half century (1960–2013) from 26 meteorological stations in northern China (Jing-Jin-Ji district) and attempts to identify spatial and temporal changes based on ten indices for extreme precipitation. Our analysis showed that all regionally averaged extreme precipitation indices were characterized by decreasing trends, of which the maximum one-day and five-day precipitation amounts (RX1day and RX5day) exhibited significant decreasing trends. We further considered possible triggering mechanisms for these trends, such as the recent continual weakening of the East Asian summer monsoon, although the detailed physical mechanisms need further study. Our analysis also showed that extreme precipitation patterns have varied spatially and exhibited a clear increasing trend from the northwest to the southeast except for consecutive dry days (CDD) and consecutive wet days (CWD). A correlation analysis showed that all indices except CDD had significant positive correlations with annual total precipitation(ATP); all indices except CDD and CWD had negative correlations with station elevation. Our results highlight the importance of understanding the patterns of changes in precipitation extremes that provide essential information for water resource management, natural hazard prevention and mitigation, and reliable future climate and environmental projections for policy makers in the Jing-Jin-Ji district. The results indicated that a higher spatial and temporal resolution analysis of extreme precipitation is needed in the study area.

Are oceanic fronts ecotones? Seasonal changes along the subtropical front show fronts as bacterioplankton transition zones but not diversity hotspots.

Ecotones are regarded as diversity hotspots in terrestrial systems, but it is unknown if this 'ecotone effect' occurs in the marine environment. Oceanic fronts are widespread mesoscale features, present in the boundary between different water masses, and are arguably the best potential examples of ecotones in the ocean. Here we performed the first seasonal study along an oceanic front, combining 16S rRNA gene sequencing coupled with a high spatial resolution analysis of the physical properties of the water masses. Using the Subtropical Frontal Zone off New Zealand we demonstrate that fronts delimit shifts in bacterioplankton community composition between water masses, but that the strength of this effect is seasonally dependent. While creating a transition zone where physicochemical parameters and bacterioplankton communities get mixed, this ecotone does not result in increased diversity. Thus unlike terrestrial ecotones, oceanic fronts are boundaries but not hotspots of bacterioplankton diversity in the ocean.

Fast Spatial Resolution Analysis of Quadratic Penalized Least-Squares Image Reconstruction With Separate Real and Imaginary Roughness Penalty: Application to fMRI.

Penalized least-squares iterative image reconstruction algorithms used for spatial resolution-limited imaging, such as functional magnetic resonance imaging (fMRI), commonly use a quadratic roughness penalty to regularize the reconstructed images. When used for complex-valued images, the conventional roughness penalty regularizes the real and imaginary parts equally. However, these imaging methods sometimes benefit from separate penalties for each part. The spatial smoothness from the roughness penalty on the reconstructed image is dictated by the regularization parameter(s). One method to set the parameter to a desired smoothness level is to evaluate the full width at half maximum of the reconstruction method's local impulse response. Previous work has shown that when using the conventional quadratic roughness penalty, one can approximate the local impulse response using an FFT-based calculation. However, that acceleration method cannot be applied directly for separate real and imaginary regularization. This paper proposes a fast and stable calculation for this case that also uses FFT-based calculations to approximate the local impulse responses of the real and imaginary parts. This approach is demonstrated with a quadratic image reconstruction of fMRI data that uses separate roughness penalties for the real and imaginary parts.

Geographic information system-based spatial analysis of population distribution in Banten province - Indonesia

Population distribution is one of the of disaster vulnerability parameters needed in a disaster risk assessment. The analysis approaches to determine the spatial population distribution can use many methodological alternatives. The general approach used in Indonesia is based on the results of a survey or census, where the number of population density is distributed evenly within the administrative borders. Another approach using Random Regression Tree model-based Forest Mapping is used by Worldpop. Both methodologies have their respective advantages and disadvantages. This study was conducted by combining these two methods where some data and parameters are added as driving factors on the scale spatial resolution analysis (grid size) 0.000833333 decimal degrees (approximately 100 m in the equatorial region) for a case study in Banten Province. Data processing is performed by raster analysis approach and GIS. The results are more affordable, meet cost requirements, and can be utilized to calculate the level of disaster risk in the area.

Impact of short duration, high-flow H2 annealing on graphene synthesis and surface morphology with high spatial resolution assessment of coverage

Treatment of graphene growth substrates with H2 has long been known to impact the quality of deposited graphene. However, the parameters for hydrogen treatment that are considered the optimum – very long anneals under low hydrogen concentrations – are often undesirable for practical reasons. In this paper we optimize anneal parameters for fast anneals of <1 h, via investigation of both substrate surface modification and graphene growth quality using a number of traditional and novel experimental techniques. Our results indicate a dual effect of H2 annealing on the surface morphology of the copper substrate, and consequent graphene growth quality, whereby H2 passivates and smoothens the Cu surface, causing it to become morphologically more favorable for graphene growth, but may in large quantities make the surface less chemically favorable, limiting the quality of grown graphene. Moreover, we use a novel method based on Atomic Force Microscopy (AFM) for higher spatial resolution analysis of the homogeneity of graphene using maps of the Hamaker coefficient.

Stopping power accuracy and achievable spatial resolution of helium ion imaging using a prototype particle CT detector system.

A precise relative stopping power map of the patient is crucial for accurate particle therapy. Charged particle imaging determines the stopping power either tomographically – particle computed tomography (pCT) – or by combining prior knowledge from particle radiography (pRad) and x-ray CT. Generally, multiple Coulomb scattering limits the spatial resolution. Compared to protons, heavier particles scatter less due to their lower charge/mass ratio. A theoretical framework to predict the most likely trajectory of particles in matter was developed for light ions up to carbon and was found to be the most accurate for helium comparing for fixed initial velocity. To further investigate the potential of helium in particle imaging, helium computed tomography (HeCT) and radiography (HeRad) were studied at the Heidelberg Ion-Beam Therapy Centre (HIT) using a prototype pCT detector system registering individual particles, originally developed by the U.S. pCT collaboration. Several phantoms were investigated: modules of the Catphan QA phantom for analysis of spatial resolution and achievable stopping power accuracy, a paediatric head phantom (CIRS) and a custommade phantom comprised of animal meat enclosed in a 2 % agarose mixture representing human tissue. The pCT images were reconstructed applying the CARP iterative reconstruction algorithm. The MTF10% was investigated using a sharp edge gradient technique. HeRad provides a spatial resolution above that of protons (MTF1010%=6.07 lp/cm for HeRad versus MTF10%=3.35 lp/cm for proton radiography). For HeCT, the spatial resolution was limited by the number of projections acquired (90 projections for a full scan). The RSP accuracy for all inserts of the Catphan CTP404 module was found to be 2.5% or better and is subject to further optimisation. In conclusion, helium imaging appears to offer higher spatial resolution compared to proton imaging. In future studies, the advantage of helium imaging compared to other imaging modalities in clinical applications will be further explored.

Nanoelectrochemical architectures for high-spatial-resolution single cell analysis

The analysis of single cells instead of cell populations is important for characterizing cellular heterogeneity and elucidating the cellular signalling pathways. Nanoelectrodes have emerged as an increasingly important tool for biomolecule analyses at the single-cell level with high spatial or temporal resolution. Various electrochemical methods, such as amperometry and scanning electrochemical microscopy (SECM), have been applied. Research to date has focused on the development of new nanoelectrochemical architectures, such as arrays, to achieve higher spatial resolution and faster analysis rates for single-cell analysis. In this review, the fabrication of these new nanoelectrochemical architectures and their applications in high spatial resolution single-cell analyses are discussed. The recent progress of Chinese researchers is highlighted.

Further Development and Application of High-Order Spectral Volume Methods for Compressible Flows

The present work investigates the high-order spectral finite volume (SFV) method with emphasis on applicability aspects for compressible flows. The intent is to improve the understanding and implementation of numerical techniques related to high-order unstructured grid schemes. In that regard, a hierarchical moment limiter and high-order mesh capability are developed for a two-dimensional Euler SFV solver. The limiter formulation and geometry interpreter for high-order mesh creation are new contributions for the SFV method. Literature test cases are evaluated to assess the interaction of curved mesh, limiter and spatial reconstruction features of the SFV scheme. An order of accuracy study is presented along with steady and unsteady problems with strong shock waves and other discontinuities typical of compressible flows. Moreover, second, third and fourth-order spatial resolution analyses are explored and the SFV results are compared with results from different numerical methods.

Multiparametric monitoring of microbial faecal pollution reveals the dominance of human contamination along the whole Danube River

The microbial faecal pollution of rivers has wide-ranging impacts on a variety of human activities that rely on appropriate river water quality. Thus, detailed knowledge of the extent and origin of microbial faecal pollution is crucial for watershed management activities to maintain safe water use. In this study, the microbial faecal pollution levels were monitored by standard faecal indicator bacteria (SFIB) along a 2580 km stretch of the Danube, the world's most international river, as well as the Danube's most important tributaries. To track the origin of faecal pollution, host-associated Bacteroidetes genetic faecal marker qPCR assays for different host groups were applied in concert with SFIB. The spatial resolution analysis was followed by a time resolution analysis of faecal pollution patterns over 1 year at three selected sites. In this way, a comprehensive faecal pollution map of the total length of the Danube was created, combining substantiated information on both the extent and origin of microbial faecal pollution. Within the environmental data matrix for the river, microbial faecal pollution constituted an independent component and did not cluster with any other measured environmental parameters. Generally, midstream samples representatively depicted the microbial pollution levels at the respective river sites. However, at a few, somewhat unexpected sites, high pollution levels occurred in the lateral zones of the river while the midstream zone had good water quality. Human faecal pollution was demonstrated as the primary pollution source along the whole river, while animal faecal pollution was of minor importance. This study demonstrates that the application of host-associated genetic microbial source tracking markers in concert with the traditional concept of microbial faecal pollution monitoring based on SFIB significantly enhances the knowledge of the extent and origin of microbial faecal pollution patterns in large rivers. It constitutes a powerful tool to guide target-oriented water quality management in large river basins.

The analytical limits of modeling short diffusion timescales

Diffusion modeling of chemical zonation in crystals and glasses is a widely used method of quantifying the timescales of a variety of geological processes. Obtaining timescale information from diffusion modeling relies on fitting modeled diffusion profiles to measured compositional gradients. Thus analytical factors, such as spatial resolution, analysis location and analytical uncertainty have the potential to limit the accuracy and precision of calculated diffusion timescales, especially when the resolution of the individual analyses approaches the width of the observed diffusion gradient. Herein we use a probabilistic modeling approach to assess the accuracy of timescales based on diffusion modeling at various spatial resolutions and diffusivities. We have calculated synthetic 1D diffusion profiles produced from simple step function geometries at various diffusivities and timescales and then resampled these at common analytical spatial resolutions. Standard diffusion modeling techniques were used to estimate apparent diffusion timescales from the resampled profiles to compare with the “true” synthetic times. Results confirm that for a given diffusivity, higher analytical spatial resolution gives access to shorter timescales, and that for each analytical resolution there is a minimum threshold timescale, below which diffusion modeling significantly overestimates the true timescale. The accuracy of short diffusion timescales depends on the width of the diffusion gradient (the portion of a profile that has been modified by diffusion) relative to the analytical spatial resolution, with models becoming accurate (within 20%) at a gradient width/spot size ratio>2. The precision of diffusion timescales depends on the gradient width to spot size ratio, the magnitude of analytical uncertainty and the magnitude of the compositional difference across the step function boundary. Precision is improved with a large gradient width/spot size ratio, and where the magnitude of the compositional difference across the step function boundary is large relative to the analytical uncertainty. We present a generalized method to quantify these threshold timescales for any given spatial resolution and diffusivity, and present simple guidelines to aid in selecting compositional profiles that will produce more accurate diffusion timescale estimates.

Analytical Spatial Resolution in EPMA: What is it and How can it be Estimated?

Analytical Spatial Resolution in EPMA: What is it and How can it be Estimated?

High Spatial Resolution and Wide Range EDS Analysis with FE-SEM

High Spatial Resolution and Wide Range EDS Analysis with FE-SEM

Spatial Resolution Analysis for Ultrawideband Bistatic Forward-Looking SAR

The ultrawideband (UWB) bistatic forward-looking synthetic aperture radar (BFSAR) can realize the high-resolution imaging in the forward direction of the transmitter/receiver, so it has significant applications in both civil and military fields. However, compared to the general narrowband side-looking bistatic synthetic aperture radar systems, the UWB BFSAR systems have larger fractional signal bandwidth and more special acquisition geometry, which will affect the behavior of spatial resolutions. Current methods for spatial resolution analysis of the UWB BFSAR are unsuitable because they do not consider the effects of these two special issues. This letter analyzes the special behavior of spatial resolutions in the UWB BFSAR, and the straightforward gradient method is utilized and extended based on the analysis to calculate the spatial resolutions. The theoretical analysis shows that the range resolution can be calculated by the traditional gradient method directly but the Doppler resolution should be calculated by the extended method. Simulated results verify the correctness of the theoretical analysis and the validity of the proposed method.

INVESTIGATING THE POTENTIAL OF DEEP NEURAL NETWORKS FOR LARGE-SCALE CLASSIFICATION OF VERY HIGH RESOLUTION SATELLITE IMAGES

Abstract. Semantic classification is a core remote sensing task as it provides the fundamental input for land-cover map generation. The very recent literature has shown the superior performance of deep convolutional neural networks (DCNN) for many classification tasks including the automatic analysis of Very High Spatial Resolution (VHR) geospatial images. Most of the recent initiatives have focused on very high discrimination capacity combined with accurate object boundary retrieval. Therefore, current architectures are perfectly tailored for urban areas over restricted areas but not designed for large-scale purposes. This paper presents an end-to-end automatic processing chain, based on DCNNs, that aims at performing large-scale classification of VHR satellite images (here SPOT 6/7). Since this work assesses, through various experiments, the potential of DCNNs for country-scale VHR land-cover map generation, a simple yet effective architecture is proposed, efficiently discriminating the main classes of interest (namely buildings, roads, water, crops, vegetated areas) by exploiting existing VHR land-cover maps for training.

Passive Optical Sensing of the Near-Surface Wind-Driven Current Profile

AbstractEstimation of near-surface current is essential to the estimation of upper-ocean material transport. Wind forcing and wave motions are dominant in the near-surface layer [within O(0.01) m of the surface], where the highly sheared flows can differ greatly from those at depth. This study presents a new method for remotely measuring the directional wind and wave drift current profile near to the surface (between 0.01 and 0.001 m for the laboratory and between 0.1 and 0.001 m for the field). This work follows the spectral analysis of high spatial (0.002 m) and temporal resolution (60 Hz) wave slope images, allowing for the evaluation of near-surface current characteristics without having to rely on instruments that may disturb the flow. Observations gathered in the 15 m × 1 m × 1 m wind-wave flume at the University of Miami’s Surge-Structure-Atmosphere Interaction (SUSTAIN) facility show that currents retrieved via this method agree well with the drift velocity of camera-tracked dye. Application of this method to data collected in the mouth of the Columbia River (MCR) indicates the presence of a near-surface current component that departs considerably from the tidal flow and may be steered by the wind stress. These observations demonstrate that wind speed–based parameterizations alone may not be sufficient to estimate wind drift and to hold implications for the way in which surface material (e.g., debris or spilled oil) transport is estimated when atmospheric stress is of relatively high magnitude or is steered off the mean wind direction.

Ultra-Low kV EDS – A New Approach to Improved Spatial Resolution, Surface Sensitivity, and Light Element Compositional Imaging and Analysis in the SEM

Ultra-Low kV EDS – A New Approach to Improved Spatial Resolution, Surface Sensitivity, and Light Element Compositional Imaging and Analysis in the SEM

Analysis of spatial resolution of an experiment on verification of the equivalence principle for a neutron by the diffraction method

Investigations of the spatial resolution of a setup for verification of the equivalence of inertial and gravitational masses of a neutron by the method of diffraction in a perfect crystal have been performed. Tests were conducted at Bragg angles of 74°–82°. A decrease in spatial resolution at Bragg angles >78° is detected.