Low-frequency currents at the northern shelf edge of the Grand Banks

1996 ◽  
Vol 101 (C6) ◽  
pp. 14223-14235 ◽  
Author(s):  
B. M. DeTracey ◽  
C. L. Tang ◽  
P. C. Smith
Keyword(s):  
Low Frequency ◽  
Shelf Edge ◽  
Grand Banks ◽  
Northern Shelf

scholarly journals Pre-Wisconsin stratigraphy and paleoclimates off Atlantic Canada, and its bearing on glaciation in Québec

2010 ◽  
Vol 31 (1-2) ◽  
pp. 15-22 ◽  
Author(s):  
M. Alam ◽  
D. J. W. Piper
Keyword(s):  
Continental Shelf ◽  
Ice Sheet ◽  
Atlantic Canada ◽  
Shelf Edge ◽  
Glacial History ◽  
Grand Banks

Cores from tops of seamounts close to the continental shelf west of the Grand Banks contain sequences of alternating clays (representing glacials) and foram nanno ooze (deposited in warmer periods), back to the Pliocene. Although sedimentation in the cores is controlled primarily by glacial conditions on the Grand Banks and Laurentian Channel, glacial history further inland can be inferred. The Wisconsin sequence shows two cool interstadials and one rather warmer one, correlable with the Plum Point, Port Talbot and St. Pierre Interstadials. Clay sedimentation during Wisconsin glacial stages was minor, suggesting glaciers did not extend to the shelf edge. In the late lllinoian, there was a major influx of red sediments, indicating significant erosion of the Gulf of St. Lawrence and Laurentian Channel. Glaciation was more extensive than during the Wisconsin. Two lllinoian interstadials, with temperatures between those of the Plum Point and St. Pierre interstadials are recognised. Early lllinoian glaciation was the most severe yet recognised in the cores. Sedimentation appears to have been controlled by the advance of a Newfoundland — Labrador — E. Québec ice sheet across the Grand Banks.

Paleocontinental slopes of East Coast Geosyncline (Canadian Atlantic margin)

1977 ◽  
Vol 14 (11) ◽  
pp. 2553-2564 ◽  
Author(s):  
Lewis H. King ◽  
Ian F. Young
Keyword(s):  
Newfoundland And Labrador ◽  
East Coast ◽  
Shelf Edge ◽  
Mass Wasting ◽  
Scotian Shelf ◽  
Grand Banks ◽  
Shelf Slope ◽  
Seismic Reflection Profiles ◽  
Atlantic Margin ◽  
Upper Slope

A study of processed seismic reflection profiles along the eastern Canadian continental margin indicates the occurrence at depth of paleocontinental slopes of Cenozoic–Mesozoic age, generally in the vicinity of the present continental slope. The paleoslopes are of two general types, constructional and destructional, formed respectively by progradational processes and mass wasting. The inclined beds of the progradational sequence (clinoform beds) represent the constructional slopes and were probably formed at times when deposition was simultaneous on the shelf, slope, and rise. Conditions leading to the establishment of a relatively deep shelf edge would favor constructional slope formation and preservation. A relatively shallow shelf edge, common during times of low sea level, would promote cutback at the shelf edge and upper slope and lead to the formation of destructional slopes. The depth of the shelf edge is mainly established by the balance between rates of sedimentation and subsidence in conjunction with the processes arising from variations in sea level.The sequence of constructional and destructional paleocontinental slopes varies widely along the Canadian Atlantic margin. On the western Scotian Shelf adjacent to the LaHave Platform the paleoslopes are mainly destructional and are in proximity, with only fragmental expression of former constructional slopes remaining. On the eastern Scotian Shelf and Grand Banks destructional paleoslopes are widely spaced in section between thick areas of constructional slope development. Paleoslopes along the northeast Newfoundland and Labrador Shelves are mainly constructional. The differences may be related to age of opening of the Atlantic Basin.The type and distribution of paleocontinental slopes along a margin could influence the migration of hydrocarbons from the eugeocline to the miogeocline.

The Shelf-Edge Frontal Structure in the Central East China Sea and Its Impact on Low-Frequency Acoustic Propagation

2004 ◽  
Vol 29 (4) ◽  
pp. 1011-1031 ◽  
Author(s):  
S.R. Ramp ◽  
C.-S. Chiu ◽  
F.L. Bahr ◽  
Y. Qi ◽  
P.H. Dahl ◽  
...  
Keyword(s):  
East China Sea ◽  
Low Frequency ◽  
Acoustic Propagation ◽  
East China ◽  
Shelf Edge ◽  
China Sea ◽  
Frontal Structure

scholarly journals Coastline Direction, Interannual Flow, and the Strong El Niño Currents along Australia's Nearly Zonal Southern Coast

2004 ◽  
Vol 34 (11) ◽  
pp. 2373-2381 ◽  
Author(s):  
Jianke Li ◽  
Allan J. Clarke
Keyword(s):  
Sea Level ◽  
El Niño ◽  
El Nino ◽  
Low Frequency ◽  
Equatorial Pacific ◽  
Shelf Edge ◽  
Southern Coast ◽  
Equatorial Pacific Ocean ◽  
Western Equatorial Pacific ◽  
Coastal Sea

Abstract The western equatorial Pacific Ocean El Niño signal leaks through the gappy western equatorial Pacific Ocean boundary to the western and southern coasts of Australia. Ocean Topography Experiment (TOPEX)/Poseidon sea level data and coastal tide gauge measurements show that off the northwest coast the low-frequency signal propagates westward as large-scale Rossby waves. However, along the nearly zonal southern coast, particle displacements are nearly zonal near the coast and experience no planetary vorticity change. As a consequence, the Rossby wave mechanism fails, and theory suggests that the signal should decay from the shelf edge with baroclinic Rossby radius-of-deformation scale. High-resolution along-track TOPEX/Poseidon sea level heights show that the interannual height signal does decay rapidly seaward of the shelf edge with this scale. The sharp fall in sea level and geostrophic balance imply strong (∼10 cm s−1) low-frequency currents seaward of the shelf edge. On the shelf, interannual flow is in the same direction as the shelf-edge flow but is much weaker. The anomalous flows tend to be eastward during La Niña, when the western equatorial Pacific and Australian coastal sea levels are unusually high, and westward during El Niño when coastal sea levels tend to be anomalously low. The anomalous low-frequency flows can transport larvae large distances, enhancing the recruitment of Australian salmon to nursery grounds in the eastern part of the southern coast when the coastal sea level is higher than normal and decreasing recruitment when it is lower than normal.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

Lectin Binding to Human Breast Tumor Cells

1976 ◽  
Vol 34 ◽  
pp. 34-35
Author(s):  
Robert E. Nordquist ◽  
J. Hill Anglin ◽  
Michael P. Lerner
Keyword(s):  
Carcinoma Cell ◽  
Ricinus Communis ◽  
Lectin Binding ◽  
Low Frequency ◽  
Breast Carcinoma Cell Line ◽  
Human Breast ◽  
Human Breast Tumor ◽  
Duct Carcinoma ◽  
Specific Antigens ◽  
Ricin Agglutinin

A human breast carcinoma cell line (BOT-2) was derived from an infiltrating duct carcinoma (1). These cells were shown to have antigens that selectively bound antibodies from breast cancer patient sera (2). Furthermore, these tumor specific antigens could be removed from the living cells by low frequency sonication and have been partially characterized (3). These proteins have been shown to be around 100,000 MW and contain approximately 6% hexose and hexosamines. However, only the hexosamines appear to be available for lectin binding. This study was designed to use Concanavalin A (Con A) and Ricinus Communis (Ricin) agglutinin for the topagraphical localization of D-mannopyranosyl or glucopyranosyl and D-galactopyranosyl or DN- acetyl glactopyranosyl configurations on BOT-2 cell surfaces.

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

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