6,456 research outputs found
Method for detecting surface motions and mapping small terrestrial or planetary surface deformations with synthetic aperture radar
A technique based on synthetic aperture radar (SAR) interferometry is used to measure very small (1 cm or less) surface deformations with good resolution (10 m) over large areas (50 km). It can be used for accurate measurements of many geophysical phenomena, including swelling and buckling in fault zones, residual, vertical and lateral displacements from seismic events, and prevolcanic swelling. Two SAR images are made of a scene by two spaced antennas and a difference interferogram of the scene is made. After unwrapping phases of pixels of the difference interferogram, surface motion or deformation changes of the surface are observed. A second interferogram of the same scene is made from a different pair of images, at least one of which is made after some elapsed time. The second interferogram is then compared with the first interferogram to detect changes in line of sight position of pixels. By resolving line of sight observations into their vector components in other sets of interferograms along at least one other direction, lateral motions may be recovered in their entirety. Since in general, the SAR images are made from flight tracks that are separated, it is not possible to distinguish surface changes from the parallax caused by topography. However, a third image may be used to remove the topography and leave only the surface changes
Control of germ-band retraction in Drosophila by the zinc-finger protein HINDSIGHT
Drosophila embryos lacking hindsight gene function have a
normal body plan and undergo normal germ-band
extension. However, they fail to retract their germ bands.
hindsight encodes a large nuclear protein of 1920 amino
acids that contains fourteen C2H2-type zinc fingers, and
glutamine-rich and proline-rich domains, suggesting that it
functions as a transcription factor. Initial embryonic
expression of hindsight RNA and protein occurs in the
endoderm (midgut) and extraembryonic membrane
(amnioserosa) prior to germ-band extension and continues
in these tissues beyond the completion of germ-band retraction. Expression also occurs in the developing tracheal system, central and peripheral nervous systems, and the ureter of the Malpighian tubules. Strikingly, hindsight is not expressed in the epidermal ectoderm which is the tissue that undergoes the cell shape changes and movements during germ-band retraction. The embryonic midgut can be eliminated without affecting germ-band retraction.
However, elimination of the amnioserosa results in the
failure of germ-band retraction, implicating amnioserosal
expression of hindsight as crucial for this process. Ubiquitous expression of hindsight in the early embryo rescues germ-band retraction without producing dominant gainof-function defects, suggesting that hindsight’s role in
germ-band retraction is permissive rather than instructive.
Previous analyses have shown that hindsight is required for
maintenance of the differentiated amnioserosa (Frank, L.
C. and Rushlow, C. (1996) Development 122, 1343-1352).
Two classes of models are consistent with the present data.
First, hindsight’s function in germ-band retraction may be
limited to maintenance of the amnioserosa which then plays
a physical role in the retraction process through contact
with cells of the epidermal ectoderm. Second, hindsight
might function both to maintain the amnioserosa and to
regulate chemical signaling from the amnioserosa to the
epidermal ectoderm, thus coordinating the cell shape
changes and movements that drive germ-band retraction
Paleogeologic map of the sub-Pennsylvanian Chesterian (Upper Mississippian) surface in the Illinois basin
Cover title."Prepared in cooperation with the Indiana Geological Survey, Bloomington and the Kentucky Geological Survey, Lexington."Part of illustrative matter in pocket.Bibliography: p. 14
National Study of Individual Chapter 11 Bankruptcies
Article published in the ABI Law Review
Cross-sectional associations between variations in ankle shape by statistical shape modeling, injury history, and race : the Johnston County Osteoarthritis Project
Rheumatology Research Foundation Medical Student Preceptorship Award (Lateef/Nelson), NIAMS K23 AR061406 (Nelson); NIH/NIAMS P60AR064166 and U01DP003206 (Jordan/Renner), NIH/NIAMS R01AR067743 (Golightly). The funders had no role in study design; collection, analysis, or interpretation of data; writing the manuscript or the decision to submit for publication.Peer reviewedPublisher PD
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