scholarly journals Source geometry from exceptionally high resolution long period event observations at Mt Etna during the 2008 eruption

2009 ◽  
Vol 36 (24) ◽  
Author(s):  
Louis De Barros ◽  
Christopher J. Bean ◽  
Ivan Lokmer ◽  
Gilberto Saccorotti ◽  
Luciano Zuccarello ◽  
...  
Keyword(s):  
High Resolution ◽  
Long Period ◽  
Mt Etna ◽  
Source Geometry ◽  
Long Period Event

HRTEM study of valleriite, a hydroxide-bearing copper sulfide

1990 ◽  
Vol 48 (4) ◽  
pp. 462-463
Author(s):  
S. Wang ◽  
P. R. Buseck
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Copper Sulfide ◽  
Carbonaceous Chondrite ◽  
Structural Data ◽  
Basic Structure ◽  
Long Period ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Wavy Structure

Valleriite is an unusual mineral, consisting of intergrowths of sulfide layers (corresponding in structure to the mineral smythite - Fe9S11) and hydroxide layers (corresponding to brucite - Mg(OH2)). It has a composition of approximately 1.526[Mg.68Al.32(OH)2].[Fe1.07Cu.93S2] and consists of two interpenetrating lattices, each of which retains its individual structural and diffraction characteristics parallel to the layering. The valleriite structure is related to that of tochilinite, an unusual iron-rich mineral that is of considerable interest for the origin of certain carbonaceous chondrite meteorites and to those of franckeite and cylindrite, two minerals that are of interest because of their unique morphological and crystallographic properties, e.g., the distinctive curved form of cylindrite and the perfect mica-like cleavage with unusual striations and the long-period wavy structure of franckeite.Our selected-area electron diffraction (SAED) patterns and high-resolution transmission electron microscope (HRTEM) images of valleriite provide new structural data. A basic structure and a new superstructure have been observed.

Crystal Structures of Fragments D and Double-D from Fibrinogen and Fibrin

1999 ◽  
Vol 82 (08) ◽  
pp. 271-276 ◽  
Author(s):  
Glen Spraggon ◽  
Stephen Everse ◽  
Russell Doolittle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Crystal Structures ◽  
Structure And Function ◽  
X Ray ◽  
Long Period ◽  
And Function

IntroductionAfter a long period of anticipation,1 the last two years have witnessed the first high-resolution x-ray structures of fragments from fibrinogen and fibrin.2-7 The results confirmed many aspects of fibrinogen structure and function that had previously been inferred from electron microscopy and biochemistry and revealed some unexpected features. Several matters have remained stubbornly unsettled, however, and much more work remains to be done. Here, we review several of the most significant findings that have accompanied the new x-ray structures and discuss some of the problems of the fibrinogen-fibrin conversion that remain unresolved. * Abbreviations: GPR—Gly-Pro-Arg-derivatives; GPRPam—Gly-Pro-Arg-Pro-amide; GHRPam—Gly-His-Arg-Pro-amide

scholarly journals Exploring the robustness of Keplerian signals to the removal of active and telluric features

2020 ◽  
Vol 500 (1) ◽  
pp. 548-557
Author(s):  
M Lisogorskyi ◽  
H R A Jones ◽  
F Feng ◽  
R P Butler ◽  
S Vogt
Keyword(s):  
Monte Carlo ◽  
High Resolution ◽  
Monte Carlo Simulations ◽  
Large Amplitude ◽  
Absorption Cell ◽  
Stellar Rotation ◽  
Long Period ◽  
Active Line ◽  
Low Amplitude ◽  
Rotation Signal

ABSTRACT We examine the influence of activity- and telluric-induced radial velocity (RV) signals on high-resolution spectra taken with an iodine absorption cell. We exclude 2-$\mathring{\rm A}$ spectral chunks containing active and telluric lines based on the well-characterized K1V star α Centauri B and illustrate the method on Epsilon Eridani – an active K2V star with a long-period, low-amplitude planetary signal. After removal of the activity- and telluric-sensitive parts of the spectrum from the RV calculation, the significance of the planetary signal is increased and the stellar rotation signal disappears. In order to assess the robustness of the procedure, we perform Monte Carlo simulations based on removing random chunks of the spectrum. Simulations confirm that the removal of lines impacted by activity and tellurics provides a method for checking the robustness of a given Keplerian signal. We also test the approach on HD 40979, which is an active F8V star with a large-amplitude planetary signal. Our Monte Carlo simulations reveal that the significance of the Keplerian signal in the F star is much more sensitive to wavelength. Unlike the K star, the removal of active lines from the F star greatly reduces the RV precision. In this case, our removal of a K star active line from an F star does not a provide a simple useful diagnostic because it has far less RV information and heavily relies on the strong active lines.

scholarly journals Infrared Spectroscopy of Molecules in Circumstellar Material

1980 ◽  
Vol 87 ◽  
pp. 515-524 ◽  
Author(s):  
Donald N. B. Hall
Keyword(s):  
Infrared Spectroscopy ◽  
High Resolution ◽  
Red Giants ◽  
Circumstellar Material ◽  
Long Period ◽  
Long Period Variables ◽  
Vibration Rotation ◽  
Very High

High resolution spectra of red giants and long period variables exhibit lines of infrared CO vibration-rotation bands arising in circumstellar material. In the few such stars so far observed at very high resolution (≲ 1 km/s) the circumstellar material appears localized in 3 distinct regimes with temperatures of 800K, 200K and 75K and expansion velocities of 0, 10 and 16 km/s rather than being uniformly distributed.

Feature selection of seismic waveforms for long period event detection at Cotopaxi Volcano

2016 ◽  
Vol 316 ◽  
pp. 34-49 ◽  
Author(s):  
R.A. Lara-Cueva ◽  
D.S. Benítez ◽  
E.V. Carrera ◽  
M. Ruiz ◽  
J.L. Rojo-Álvarez
Keyword(s):  
Feature Selection ◽  
Event Detection ◽  
Long Period ◽  
Seismic Waveforms ◽  
Cotopaxi Volcano ◽  
Selection Of ◽  
Long Period Event
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