scholarly journals Airborne fine-resolution UHF radar: an approach to the study of englacial reflections, firn compaction and ice attenuation rates

2015 ◽  
Vol 61 (225) ◽  
pp. 89-100 ◽  
Author(s):  
Cameron Lewis ◽  
Sivaprasad Gogineni ◽  
Fernando Rodriguez-Morales ◽  
Ben Panzer ◽  
Theresa Stumpf ◽  
...  
Keyword(s):  
Dynamic Range ◽  
High Sensitivity ◽  
Ultra Wideband ◽  
West Antarctica ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
Transmission Coefficients ◽  
Ice Surface ◽  
Wide Range ◽  
Fine Resolution

AbstractWe have built and operated an ultra-wideband UHF pulsed-chirp radar for measuring firn stratigraphy from airborne platforms over the ice sheets of Greenland and West Antarctica. Our analysis found a wide range of capabilities, including imaging of post firn–ice transition horizons and sounding of shallow glaciers and ice shelves. Imaging of horizons to depths exceeding 600 m was possible in the colder interior regions of the ice sheet, where scattering from the ice surface and inclusions was minimal. The radar’s high sensitivity and large dynamic range point to loss tangent variations as the dominant mechanism for these englacial reflective horizons. The radar is capable of mapping interfaces with reflection coefficients as low as −80 dB near the firn–ice transition and as low as −64 dB at depths of 600 m. We found that firn horizon reflectivity strongly mirrored density variance, a result of the near-unity interfacial transmission coefficients. Zones with differing compaction mechanisms were also apparent in the data. We were able to sound many ice shelves and areas of shallow ice. We estimated ice attenuation rates for a few locations, and our attenuation estimates for the Ross Ice Shelf, West Antarctica, appear to agree well with earlier reported results.

scholarly journals Modeling the dynamic response of outlet glaciers to observed ice-shelf thinning in the Bellingshausen Sea Sector, West Antarctica

2018 ◽  
Vol 64 (244) ◽  
pp. 333-342 ◽  
Author(s):  
BRENT M. MINCHEW ◽  
G. HILMAR GUDMUNDSSON ◽  
ALEX S. GARDNER ◽  
FERNANDO S. PAOLO ◽  
HELEN A. FRICKER
Keyword(s):  
Dynamic Response ◽  
Mass Loss ◽  
Gravity Anomalies ◽  
Surface Elevation ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Ice Surface ◽  
Mass Losses ◽  
Bellingshausen Sea

ABSTRACTSatellite observations of gravity anomalies, ice-surface elevation and glacier velocity show significant increases in net grounded-ice-mass loss over the past decade along the Bellingshausen Sea sector (BSS), West Antarctica, in areas where warm (>1°C) sea water floods the continental shelf. These observations provide compelling but indirect evidence that mass losses are driven primarily by reduced buttressing from the floating ice shelves caused by ocean-driven ice-shelf thinning. Here, we combine recent observations of ice velocity, thickness and thickness changes with an ice flow model to study the instantaneous dynamic response of BSS outlet glaciers to observed ice-shelf thinning, alone. Our model results show that multiple BSS outlet glaciers respond instantaneously to observed ice-shelf thinning, particularly in areas where ice shelves ground at discrete points. Increases in modeled and observed dynamic mass losses, however, account for ~5% of the mass loss rates estimated from gravity anomalies and changes in ice-surface elevation, suggesting that variations in surface mass balance may be key to understanding recent BSS mass loss. Our approach isolates the impact of ice-shelf thinning on glacier flow and shows that if ice-shelf thinning continues at or above current rates, total BSS mass loss will increase in the next decade.

scholarly journals Analysis of coastal change in Marie Byrd Land and Ellsworth Land, West Antarctica, using Landsat imagery

1998 ◽  
Vol 27 ◽  
pp. 33-40 ◽  
Author(s):  
Jane G. Ferrigno ◽  
Richard S. Williams ◽  
Christine E. Rosanova ◽  
Baerbel K. Lucchitta ◽  
Charles Swithinbank
Keyword(s):  
Landsat Imagery ◽  
Time Interval ◽  
Coastal Change ◽  
West Antarctica ◽  
Ice Streams ◽  
Ice Shelves ◽  
Coastline Change ◽  
Ice Surface ◽  
Iceberg Calving ◽  
Major Trend

The U.S. Geological Survey is using Landsat imagery from the early 1970s and mid- to late 1980s/early 1990s to analyze glaciological features, compile a glacier inventory, measure surface velocities of outlet glaciers, ice streams and ice shelves, determine coastline change and calculate the area and volume of iceberg calving in Antarctica. Ice-surface velocities in Marie Byrd and Ellsworth Lands, West Antarctica, range from the fast-moving Thwaites, Pine Island, Land and DeVicq Glaciers to the slower-moving ice shelves. The average ice-front velocity during the time interval of Landsat imagery, for the faster-moving outlet glaciers, was 2.9 km a-1 for Thwaites Glacier, 2.4 km a-1 for Pine Island Glacier, 2.0 km a-1 for Land Glacier and 1.4 km a-1 for DeVicq Glacier. Evaluation of coastal change from the early 1970s to the early 1990s shows advance of the floating ice front in some coastal areas and recession in others, with an overall small average advance in the entire coastal study area, but no major trend towards advance or retreat. Comparison of average ice-surface velocities with changes in the ice front has yielded estimates of iceberg calving. The total iceberg calving from the Marie Byrd Land and Ellsworth Land coasts during the study period was greater than 8500 km2 (estimated volume of about 2400 km-3) or an average of about 550 km3 a-1 (more than 150 km2 a-1). Almost 70% of this discharge is contributed by Thwaites and Pine Island Glaciers.

scholarly journals Nanotechnology in emerging liquid biopsy applications

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Despina P. Kalogianni
Keyword(s):  
Liquid Biopsy ◽  
Dynamic Range ◽  
Low Cost ◽  
Invasive Procedure ◽  
High Sensitivity ◽  
Attractive Alternative ◽  
Sample Collection ◽  
Comprehensive Overview ◽  
Early Cancer Diagnosis ◽  
Wide Range

AbstractLiquid biopsy is considered as the most attractive alternative to traditional tissue biopsies. The major advantages of this approach lie in the non-invasive procedure, the rapidness of sample collection and the potential for early cancer diagnosis and real-time monitoring of the disease and the treatment response. Nanotechnology has dynamically emerged in a wide range of applications in the field of liquid biopsy. The benefits of using nanomaterials for biosensing include high sensitivity and detectability, simplicity in many cases, rapid analysis, the low cost of the analysis and the potential for portability and personalized medicine. The present paper reports on the nanomaterial-based methods and biosensors that have been developed for liquid biopsy applications. Most of the nanomaterials used exhibit great analytical performance; moreover, extremely low limits of detection have been achieved for all studied targets. This review will provide scientists with a comprehensive overview of all the nanomaterials and techniques that have been developed for liquid biopsy applications. A comparison of the developed methods in terms of detectability, dynamic range, time-length of the analysis and multiplicity, is also provided.

scholarly journals Label-Free Assays on the BIND System

2004 ◽  
Vol 9 (6) ◽  
pp. 481-490 ◽  
Author(s):  
Brian T. Cunningham ◽  
Peter Li ◽  
Stephen Schulz ◽  
Bo Lin ◽  
Cheryl Baird ◽  
...  
Keyword(s):  
Fluorescent Dyes ◽  
Dynamic Range ◽  
Low Cost ◽  
High Sensitivity ◽  
Receptor Expression ◽  
Label Free ◽  
Protein Protein Interaction ◽  
Small Molecule Screening ◽  
Guided Mode ◽  
Wide Range

Screening of biochemical interactions becomes simpler, less expensive, and more accurate when labels, such as fluorescent dyes, radioactive markers, and colorimetric reactions, are not required to quantify detected material. SRU Biosystems has developed a biosensor technology that is manufactured on continuous sheets of plastic film and incorporated into standard microplates and microarray slides to enable label-free assays to be performed with high throughput, high sensitivity, and low cost per assay. The biosensor incorporates a narrow band guided-mode resonance reflectance filter, in which the reflected color is modulated by the attachment/detachment of biochemical material to the surface. The technology offers 4 orders of linear dynamic range and uniformity within a plate, with a coefficient of variation of 2.5%. Using conventional biochemical immobilization surface chemistries, a wide range of assay applications are enabled. Small molecule screening, cell proliferation/cytotoxicity, enzyme activity screening, protein-protein interaction, and cell membrane receptor expression are among the applications demonstrated.

scholarly journals Velocities of Thwaites Glacier and smaller glaciers along the Marie Byrd Land coast, West Antarctica

1998 ◽  
Vol 27 ◽  
pp. 47-53 ◽  
Author(s):  
C. E. Rosanova ◽  
B. K. Lucchitta ◽  
J. G. Ferrigno
Keyword(s):  
West Antarctica ◽  
Ice Shelf ◽  
Time Intervals ◽  
Ice Shelves ◽  
Radar Images ◽  
Ice Surface ◽  
Grounding Line ◽  
Glacier Ice ◽  
Surface Patterns ◽  
High Precipitation

Average velocities for time intervals ranging from < 1 to 15 years were measured by tracking ice-surface patterns on sequential Landsat and European Remote-sensing Satellite synthetic aperture radar images. Velocities ofThwaites Glacier range from 2.2 km a−1 above the grounding line to 3.4 km a−1 at the limit of measurements onThwaites Glacier ice tongue. The glacier increases in velocity by about 1 km a−1 where it crosses the grounding line. Over the period 1984-93, Thwaites Glacier ice tongue accelerated by about 0.6 kin a .Velocities of the floating part of several minor glaciers and some ice shelves are also determined: Land Glacier, 17—1.9 km a−1 ; DeVicq Glacier, 0.7-1.1 km a−1; Dotson Ice Shelf 0.2-0.5 km a−1; Gctz Ice Shelf, 0.2-0.8 km a−1; and Sulzberger Ice Shelf, 0.01 -0.02 km a−1. The high velocities along the Marie Byrd Land coast are consistent with the high precipitation rates over West Antarctica and, for some of the glaciers, the lack of buttressing ice shelves.

scholarly journals Mechanical analysis of pinning points in the Ross Ice Shelf, Antarctica

2018 ◽  
Vol 60 (78) ◽  
pp. 32-41 ◽  
Author(s):  
Holly Still ◽  
Adam Campbell ◽  
Christina Hulbe
Keyword(s):  
Ice Sheet ◽  
Mechanical Analysis ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
The Antarctic

ABSTRACTIce shelves regulate the rate of ice-sheet discharge along much of the Antarctic coastline. Pinning points, sites of localised grounding within floating ice, can in turn, regulate the flow and thickness of an ice shelf. While the net resistive effect of ice shelves has been quantified in a systematic way, few extant pinning points have been examined in detail. Here, complete force budgets are calculated and examined for ice rises and rumples in the Ross Ice Shelf, West Antarctica. The diverse features have different effects on ice shelf mechanics that do not depend simply on their size but may, we conclude, depend on the properties of seafloor materials.

scholarly journals Electrochemiluminescence Biosensors Using Screen-Printed Electrodes

Biosensors ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 118
Author(s):  
Emiliano Martínez-Periñán ◽  
Cristina Gutiérrez-Sánchez ◽  
Tania García-Mendiola ◽  
Encarnación Lorenzo
Keyword(s):  
Dna Analysis ◽  
Dynamic Range ◽  
Chemical Properties ◽  
High Sensitivity ◽  
Portable Devices ◽  
Research Fields ◽  
Sensing Applications ◽  
Screen Printed Electrodes ◽  
Wide Range ◽  
Screen Printed

Electrogenerated chemiluminescence (also called electrochemiluminescence (ECL)) has become a great focus of attention in different fields of analysis, mainly as a consequence of the potential remarkably high sensitivity and wide dynamic range. In the particular case of sensing applications, ECL biosensor unites the benefits of the high selectivity of biological recognition elements and the high sensitivity of ECL analysis methods. Hence, it is a powerful analytical device for sensitive detection of different analytes of interest in medical prognosis and diagnosis, food control and environment. These wide range of applications are increased by the introduction of screen-printed electrodes (SPEs). Disposable SPE-based biosensors cover the need to perform in-situ measurements with portable devices quickly and accurately. In this review, we sum up the latest biosensing applications and current progress on ECL bioanalysis combined with disposable SPEs in the field of bio affinity ECL sensors including immunosensors, DNA analysis and catalytic ECL sensors. Furthermore, the integration of nanomaterials with particular physical and chemical properties in the ECL biosensing systems has improved tremendously their sensitivity and overall performance, being one of the most appropriates research fields for the development of highly sensitive ECL biosensor devices.

Slow-Scan CCD Observation of Backscattering Patterns in SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1308-1309
Author(s):  
F. Ouyang ◽  
D. A. Ray ◽  
O. L. Krivanek
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Lens System ◽  
Wide Dynamic Range ◽  
Peltier Cooler ◽  
Diffraction Patterns ◽  
Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

Development of imaging plate for a TEM and its characteristics

1989 ◽  
Vol 47 ◽  
pp. 100-101
Author(s):  
N. Mori ◽  
T. Oikawa ◽  
Y. Harada ◽  
J. Miyahara ◽  
T. Matsuo
Keyword(s):  
Dynamic Range ◽  
Protective Layer ◽  
High Sensitivity ◽  
Imaging Plate ◽  
Phosphor Layer ◽  
Imaging Device ◽  
X Ray Imaging ◽  
New Type ◽  
Basic Characteristics ◽  
Reading System

The Imaging Plate (IP) is a new type imaging device, which was developed for diagnostic x ray imaging. We have reported that usage of the IP for a TEM has many merits; those are high sensitivity, wide dynamic range, and good linearity. However in the previous report the reading system was prototype drum-type-scanner, and IP was also experimentally made, which phosphor layer was 50μm thick with no protective layer. So special care was needed to handle them, and they were used only to make sure the basic characteristics. In this article we report the result of newly developed reading, printing system and high resolution IP for practical use. We mainly discuss the characteristics of the IP here. (Precise performance concerned with the reader and other system are reported in the other article.)Fig.1 shows the schematic cross section of the IP. The IP consists of three parts; protective layer, phosphor layer and support.

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