scholarly journals Photometric and Hα modulation on active stars

1996 ◽  
Vol 176 ◽  
pp. 403-410 ◽  
Author(s):  
S. Catalano ◽  
M. Rodonò ◽  
A. Frasca ◽  
G. Cutispoto
Keyword(s):  
High Resolution ◽  
Surface Activity ◽  
Three Dimensional ◽  
High Resolution Spectroscopy ◽  
Dimensional Structure ◽  
Preliminary Results ◽  
Chromospheric Activity ◽  
Photometric Monitoring ◽  
The Relationship ◽  
Shed Light

Systematic photometric monitoring of active RS CVn binaries carried out at Catania with the automatic telescope APT-80, is being complemented with Hα low- and high-resolution spectroscopy. The relationship between photospheric and chromospheric activity is investigated in order to shed light into the complex three-dimensional structure of surface activity. Preliminary results on the photometric and Hα monitoring of the active binaries, UX Ari, RS CVn, BM CVn, HK Lac, IM Peg, V 711 Tau, and EI Eri, are here reported.

Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution

1991 ◽  
Vol 49 ◽  
pp. 540-541
Author(s):  
Kenneth H. Downing ◽  
Hu Meisheng ◽  
Hans-Rudolf Went ◽  
Michael A. O'Keefe
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Atomic Resolution ◽  
Dimensional Structure ◽  
Structure Information ◽  
Resolution Electron ◽  
Scattering Effects ◽  
High Resolution Images ◽  
Effects Of Radiation

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.

scholarly journals High-resolution three-dimensional probes of biomaterials and their interfaces

2012 ◽  
Vol 370 (1963) ◽  
pp. 1337-1351 ◽  
Author(s):  
Kathryn Grandfield ◽  
Anders Palmquist ◽  
Håkan Engqvist
Keyword(s):  
High Resolution ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Controlled Drug Release ◽  
Biological Tissues ◽  
Dimensional Structure ◽  
Bone Interface ◽  
Biomaterial Interfaces ◽  
Titania Coating

Interfacial relationships between biomaterials and tissues strongly influence the success of implant materials and their long-term functionality. Owing to the inhomogeneity of biological tissues at an interface, in particular bone tissue, two-dimensional images often lack detail on the interfacial morphological complexity. Furthermore, the increasing use of nanotechnology in the design and production of biomaterials demands characterization techniques on a similar length scale. Electron tomography (ET) can meet these challenges by enabling high-resolution three-dimensional imaging of biomaterial interfaces. In this article, we review the fundamentals of ET and highlight its recent applications in probing the three-dimensional structure of bioceramics and their interfaces, with particular focus on the hydroxyapatite–bone interface, titanium dioxide–bone interface and a mesoporous titania coating for controlled drug release.

scholarly journals Vertebrobasilar Artery Geometry and Bisilar Artery Plaques: A High-Resolution Magnetic Resonance Imaging Stydy

2020 ◽  
Author(s):  
Jinmei Zheng ◽  
Bin Sun ◽  
Ruolan Lin ◽  
Yongqi Teng ◽  
Xihai Zhao ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Large Diameter ◽  
Three Dimensional ◽  
Resonance Imaging ◽  
Logistic Regression Models ◽  
Vertebrobasilar Artery ◽  
Number Of Bends ◽  
The Relationship

Abstract Background Atherosclerotic plaques are often present in regions with complicated flow patterns. Vascular morphology plays a role in hemodynamics. In this study, we investigate the relationship between the geometry of the vertebrobasilar artery system and the basilar artery (BA) plaque prevalence.Methods We enrolled 290 patients with posterior circulation ischemic stroke. We distinguished four configurations of the vertebrobasilar artery: Walking, Tuning Fork, Lambda, and No Confluence. The diameter of the vertebral artery (VA) and the number of bends in the intracranial VA segment was assessed using three-dimensional time-of-flight magnetic resonance angiography. We differentiated between multi-bending (≥ 3 bends) and oligo-bending (< 3 bends) VAs. High-resolution magnetic resonance imaging was used to evaluate BA plaques. Logistic regression models examined the relationship between the geometry type and BA plaque prevalence.Results After adjusting for sex, age, body mass index ≥ 28, hypertension, and diabetes mellitus, the Walking, Lambda, and No Confluence geometries were associated with the presence of BA plaque. Patients with multi-bending VAs in both the Walking (71.43%, P = 0.003) and Lambda group (40.43%, P = 0.018) had more plaques compared to patients with oligo-bending VAs in these groups. In the Lambda group, the diameter difference between the VAs was larger in patients with BA plaques than that in patients without BA plaques (1.4 mm vs. 0.9 mm, P < 0.001).Conclusions The Walking, Lambda, and No Confluence geometry, ≥ 3 bends in the VAs, and a large diameter difference between the VAs were associated with the presence of BA plaque.

scholarly journals Insights into the Pulsational Behaviour of δ Sct Stars

1995 ◽  
Vol 155 ◽  
pp. 337-338 ◽  
Author(s):  
L. Mantegazza ◽  
E. Poretti
Keyword(s):  
High Resolution ◽  
Resolving Power ◽  
High Resolution Spectroscopy ◽  
Full Description ◽  
Linear Dispersion ◽  
Stellar Spectra ◽  
Mode Identification ◽  
Photometric Monitoring ◽  
Scuti Stars ◽  
Made In

Extensive photometric monitoring of bright δ Scuti stars, made in the last years, allowed us to get reliable frequency determinations also in very complicated cases. Table 1 gives a full description of our photometric targets. Recently, we realized that combining photometry with simultaneous high resolution spectroscopy, in order to study line profile variations, offers the possibility to perform a much more reliable mode identification. Hence, the photometric runs of FG Vir, X Cae, HD 2724 were paired with spectroscopic ones obtained at the Coudé Auxiliary Telescope (ESO, La Silla, Chile). The stellar spectra are centred at 4508 Å and they cover a range of 37.6 Å; the resolving power is about 50000-60000 and the linear dispersion is 2.4 Å/mm.

Determining the orientation of parent β grain from one α variant in titanium alloys

2018 ◽  
Vol 51 (4) ◽  
pp. 1125-1132 ◽  
Author(s):  
Z. B. Zhao ◽  
Q. J. Wang ◽  
H. Wang ◽  
J. R. Liu ◽  
R. Yang
Keyword(s):  
Titanium Alloys ◽  
Habit Plane ◽  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Plane Normal ◽  
Β Phase ◽  
Microstructural Morphology ◽  
Backscatter Diffraction ◽  
The Relationship

The relationship between the crystallographic orientation and habit plane normal of transformed α laths in titanium alloys is discussed according to the Burgers orientation relationship and the three-dimensional structure of the α lath. A new method (orientation–trace method) is developed to determine the orientation of the parent β phase using the orientation of the α lath, which was measured by electron backscatter diffraction, and the microstructural morphology of that α variant. This approach is validated in a near-α titanium alloy. Moreover, the habit plane normal direction of the transformed α lath can be obtained from the crystallographic orientations of the α lath itself and its parent β grain. The verification and the corresponding discussion show the reliability of this approach.

400 Kv Electron Cryo-Microscopic Imaging Of Large Icosahedral Viruses Towards Atomic Resolution

1999 ◽  
Vol 5 (S2) ◽  
pp. 186-187
Author(s):  
Joanita Jakarta ◽  
Wah Chiu
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
Clinical Manifestations ◽  
Image Data ◽  
Chromatic Aberration ◽  
Dimensional Structure ◽  
Depth Of Field ◽  
Periodic Arrays ◽  
Icosahedral Viruses ◽  
Simplex Virus

Three-dimensional structure studies provide important information about the organization of macromolecules, often revealing biological mechanisms and protein structure-function relationships. 400 KV electron cryo-microscopy is an emerging technology that is proving to be a powerful tool for studying the structures of large macromolecular assemblies that are often not tractable using other techniques. Its large depth of field makes it well-suited for imaging large objects to high resolution. In addition, a high accelerating voltage minimizes chromatic aberration yielding images of higher contrast. Recently a 400 KV electron cryo-microscope has been used to image periodic arrays of tubulin to 3.5 Å and single particles at somewhat lower resolutions (13 Å) providing practical demonstrations of its usefulness in modern structural biology. In this paper we present high resolution image data of two large icosahedral viruses: herpes simplex virus IB nucleocapsid (HSV IB) and rice dwarf virus (RDV). Human herpes virus (HSV) is associated with a spectrum of diseases ranging from cold sores to more severe clinical manifestations such as mental retardation.

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