Direction‐Aware Mapping Algorithms Have Minimal Impact on Bipolar Voltage Maps Created Using High‐Resolution Multielectrode Catheters

2021 ◽  
Author(s):  
Hagai D. Yavin ◽  
Jakub Sroubek ◽  
Jonathan Yarnitsky ◽  
Zachary P. Buba ◽  
Koji Higuchi ◽  
...  
Keyword(s):  
High Resolution ◽  
Mapping Algorithms ◽  
Minimal Impact ◽  
Bipolar Voltage

Evaluating bedrock outcrop mapping algorithms across diverse landscapes

2021 ◽  
Author(s):  
Brittany Selander ◽  
Suzanne Anderson ◽  
Matthew Rossi
Keyword(s):  
High Resolution ◽  
False Positive Rate ◽  
Ground Surface ◽  
Ground Truth ◽  
Data Availability ◽  
Classification Methods ◽  
Mapping Algorithms ◽  
Positive Rate ◽  
Moderate Resolution ◽  
Bedrock Outcrop

<p>            Mapping bedrock outcrops is useful across disciplines, but is challenging in environments where ground surface visibility is obscured. The presence of soil or bedrock affects sediment production and transport, local ecology, and runoff generation. The distribution of bedrock outcrops in an area reflects the interplay between regolith production and sediment removal. Outcrop classification methods from Terrestrial-lidar produce millimeter or centimeter resolution DEMs that are highly successful because lidar penetrates through vegetation to the ground surface. However, data availability at such high resolution is limited, and the associated computational complexity required for identifying outcrop, or other surface features, is often impractical for landscape-scale analysis. Aerial lidar datasets at ~1-m resolution (e.g., moderate resolution) are more widely available and less computationally expensive than higher resolution datasets. With increasing accessibility of moderate resolution surface data, there is a need to develop outcrop classification methods and understand the efficacy of these methods across diverse environments. Our objectives are to present a simplified technique that builds on existing methods, and to examine the success of current outcrop identification methods in a variety of landscapes.</p><p>            At moderate resolution, the two most cited metrics to differentiate bedrock from soil-mantled surfaces are based on gradient (e.g., DiBiase et al., 2012) or on surface roughness (e.g., Milodowski et al., 2015). We developed a method that simplifies and combines both metrics, and that improves overall accuracy. We applied all three methods to six landscapes in the USA. For each site, we delineated ground truth from high-resolution orthoimagery for 7-10 test patches with visible ground surface, that evenly spanned 0-100% exposed outcrop. Overall accuracy, true positive rate, and false positive rate for each patch were calculated by comparing the ground truth grids to each lidar-derived outcrop grids on a cell-by-cell basis. Metric success was evaluated for each landscape by assessing the mean and distribution of performance measures across patches. Our combined metric had the highest overall accuracy in an arid, horst and graben landscape (Canyonlands National Park, Utah). It also performed well in a vegetated, high sediment load, active volcano (Mount Rainier, Washington), a canyon carved by channel incision (Boulder Canyon, Colorado), and a chaparral mixed bedrock canyon environment (Mission Trails, San Diego, California). All three methods systematically failed for portions of the landscape in glacially carved canyons (Southern Wind River Range, Wyoming) and on terraced sea cliffs (Santa Cruz County, California). These environments have significant outcrop that is both smooth and low gradient, and therefore cannot be identified using a slope or roughness-based algorithm.</p><p>            Our work highlights the importance of tailoring DEM-based bedrock mapping algorithms to its geomorphic context, and of the need for ground truth. Such data provides the basis for developing more robust methods for error evaluation. In addition, new methods are needed to identify bedrock outcrop from surface DEMs in smooth and low gradient, yet rocky landscapes.</p>

scholarly journals Comparative Analysis of Parallel Brain Activity Mapping Algorithms for High Resolution Brain Models

TecnoLógicas ◽  
2019 ◽  
Vol 22 (46) ◽  
pp. 233-243
Author(s):  
Cristhian D. Molina-Machado ◽  
Ernesto Cuartas ◽  
Juan D. Martínez-Vargas ◽  
Eduardo Giraldo
Keyword(s):  
Comparative Analysis ◽  
High Resolution ◽  
Brain Activity ◽  
Estimation Error ◽  
Computational Time ◽  
Head Model ◽  
Reconstruction Method ◽  
Mapping Algorithms ◽  
Parallel Processes ◽  
Brain Models

This paper proposes a comparative analysis between regular and parallel versions of FISTA and Tikhonov-like optimizations for solving the EEG brain mapping problem. Such comparison is performed in terms of computational time reduction and estimation error achieved by the parallelized methods. Two brain models (high- and low-resolution) are used to compare the algorithms. As a result, it can be seen that, if the number of parallel processes increases, computational time decreases significantly for all the head models used in this work, without compromising the reconstruction quality. In addition, it can be concluded that the use of a high-resolution head model produces an improvement in any source reconstruction method in terms of spatial resolution.  

Observations of the spatial structure of interstellar hydrogen

1967 ◽  
Vol 31 ◽  
pp. 45-46
Author(s):  
Carl Heiles
Keyword(s):  
High Resolution ◽  
Spatial Structure ◽  
Velocity Dispersion ◽  
Temperature Variations

High-resolution 21-cm line observations in a region aroundlII= 120°,b11= +15°, have revealed four types of structure in the interstellar hydrogen: a smooth background, large sheets of density 2 atoms cm-3, clouds occurring mostly in groups, and ‘Cloudlets’ of a few solar masses and a few parsecs in size; the velocity dispersion in the Cloudlets is only 1 km/sec. Strong temperature variations in the gas are in evidence.

Combining integrated systems-biology approaches with intervention-based experimental design provides a higher-resolution path forward for microbiome research

2019 ◽  
Vol 42 ◽  
Author(s):  
J. Alfredo Blakeley-Ruiz ◽  
Carlee S. McClintock ◽  
Ralph Lydic ◽  
Helen A. Baghdoyan ◽  
James J. Choo ◽  
...  
Keyword(s):  
Systems Biology ◽  
High Resolution ◽  
Experimental Design ◽  
Integrated Systems ◽  
Microbiome Research ◽  
Constructive Criticism

Abstract The Hooks et al. review of microbiota-gut-brain (MGB) literature provides a constructive criticism of the general approaches encompassing MGB research. This commentary extends their review by: (a) highlighting capabilities of advanced systems-biology “-omics” techniques for microbiome research and (b) recommending that combining these high-resolution techniques with intervention-based experimental design may be the path forward for future MGB research.

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Radiation Damage, Contrast and Statistics in High Resolution Biological Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 260-261
Author(s):  
Robert M. Glaeser
Keyword(s):  
High Resolution ◽  
Particle Flux ◽  
Unit Area ◽  
Signal To Noise ◽  
Resolution Image ◽  
High Resolution Image ◽  
Pass Through ◽  
Counting Statistics ◽  
The Relationship ◽  
Picture Element

It is well known that a large flux of electrons must pass through a specimen in order to obtain a high resolution image while a smaller particle flux is satisfactory for a low resolution image. The minimum particle flux that is required depends upon the contrast in the image and the signal-to-noise (S/N) ratio at which the data are considered acceptable. For a given S/N associated with statistical fluxtuations, the relationship between contrast and “counting statistics” is s131_eqn1, where C = contrast; r2 is the area of a picture element corresponding to the resolution, r; N is the number of electrons incident per unit area of the specimen; f is the fraction of electrons that contribute to formation of the image, relative to the total number of electrons incident upon the object.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

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