The determination of fluid flow at the core surface from geomagnetic observations

1988 ◽  
pp. 189-208 ◽  
Author(s):  
J. Bloxham
Keyword(s):  
Fluid Flow ◽  
Core Surface ◽  
The Core ◽  
Geomagnetic Observations

scholarly journals pygeodyn 1.0.0: a Python package for geomagnetic data assimilation

2019 ◽  
Author(s):  
Loïc Huder ◽  
Nicolas Gillet ◽  
Franck Thollard
Keyword(s):  
Data Assimilation ◽  
Stochastic Model ◽  
User Profiles ◽  
Surface Dynamics ◽  
Core Surface ◽  
The Core ◽  
Geomagnetic Data ◽  
User Friendly ◽  
Geomagnetic Observations ◽  
Python Package

Abstract. pygeodyn is a sequential geomagnetic data assimilation package written in Python. It gives access to the core surface dynamics, controlled by geomagnetic observations, by means of a stochastic model anchored to geodynamo simulation statistics. pygeodyn aims at giving access to a user-friendly and flexible data assimilation algorithm. It is designed to be tunable by the community by different means: possibility to use embedded data and priors, or to supply custom ones; tunable parameters through configuration files; adapted documentation for several user profiles. In addition, output files are directly supported by the package webgeodyn that provides a set of visualisation tools to explore the results of computations.

Imaging of ribosomal RNA-protein interactions by dark-field STEM

1989 ◽  
Vol 47 ◽  
pp. 250-251
Author(s):  
M. Boublik ◽  
V. Mandiyan ◽  
S. Tumminia ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
Nucleic Acid ◽  
16S Rrna ◽  
Dark Field ◽  
Radius Of Gyration ◽  
Central Domain ◽  
The Core ◽  
16S Rna ◽  
30S Subunit ◽  
Core Particles

Success in protein-free deposition of native nucleic acid molecules from solutions of selected ionic conditions prompted attempts for high resolution imaging of nucleic acid interactions with proteins, not attainable by conventional EM. Since the nucleic acid molecules can be visualized in the dark-field STEM mode without contrasting by heavy atoms, the established linearity between scattering cross-section and molecular weight can be applied to the determination of their molecular mass (M) linear density (M/L), mass distribution and radius of gyration (RG). Determination of these parameters promotes electron microscopic imaging of biological macromolecules by STEM to a quantitative analytical level. This technique is applied to study the mechanism of 16S rRNA folding during the assembly process of the 30S ribosomal subunit of E. coli. The sequential addition of protein S4 which binds to the 5'end of the 16S rRNA and S8 and S15 which bind to the central domain of the molecule leads to a corresponding increase of mass and increased coiling of the 16S rRNA in the core particles. This increased compactness is evident from the decrease in RG values from 114Å to 91Å (in “ribosomal” buffer consisting of 10 mM Hepes pH 7.6, 60 mM KCl, 2 m Mg(OAc)2, 1 mM DTT). The binding of S20, S17 and S7 which interact with the 5'domain, the central domain and the 3'domain, respectively, continues the trend of mass increase. However, the RG values of the core particles exhibit a reverse trend, an increase to 108Å. In addition, the binding of S7 leads to the formation of a globular mass cluster with a diameter of about 115Å and a mass of ∽300 kDa. The rest of the mass, about 330 kDa, remains loosely coiled giving the particle a “medusa-like” appearance. These results provide direct evidence that 16S RNA undergoes significant structural reorganization during the 30S subunit assembly and show that its interactions with the six primary binding proteins are not sufficient for 16S rRNA coiling into particles resembling the native 30S subunit, contrary to what has been reported in the literature.

Nauwkeurige methode voor de aanwasbepaling van het grondvlak met behulp van de Pressler-boor

1968 ◽  
Vol 12 ◽  
Author(s):  
R. Goossens
Keyword(s):  
Basal Area ◽  
Precise Determination ◽  
Maximum Diameter ◽  
Precise Method ◽  
Maximum Radius ◽  
The Core ◽  
Two Parameters

A precise method for the determination of the increment of the  basal area using the PressIer bore. Refering to  previous research showing that the basal area of the corsica pine could be  characterized by an ellips, we present in this paper a precise method for the  determination of the increment of the basal area. In this method we determine  the direction of the maximum diameter, we measure this diameter and we take a  core in one of the points of tangency of the caliper with the measured tree.  The determination of the diameter perpendicular to the maximum diameter  finishes the work wich is to be done in the forest. From the classical  measurements effectuated on the core and from the measured diameters we can  then determine the form (V) and the excentricity (e). Substituting these two  parameters in the formula 2 or 2', we can also calculate the error of a  radius measured on the core with respect to the representative radius, This  error with them allow us to correct the measured value of the minimum or the  maximum radius and we will be able to do a precise determination of the  increment.

Formation of an Iron(III) Oxo Cubane Core Fe4(μ4-O)4 from FeCl3 and the Unsymmetrical Tripodal Ligand N[(CH2CH2NH2)(CH2CH2OH)(CH2CH2CH2OH)]

2004 ◽  
Vol 59 (8) ◽  
pp. 855-858 ◽  
Author(s):  
Ekkehardt Hahn ◽  
Christoph Jocher ◽  
Thomas Lügger
Keyword(s):  
Coordination Chemistry ◽  
Structure Determination ◽  
Disodium Salt ◽  
Ferrous Chloride ◽  
Tripodal Ligand ◽  
The Core ◽  
Yellow Precipitate

AbstractThe coordination chemistry of the unsymmetric, aliphatic, tetradentate tripodal ligand N[(CH2CH2NH2)(CH2CH2OH)(CH2CH2CH2OH)] H4-1 with iron chlorides was investigated. The disodium salt of the deprotonated ligand Na2(H2-1) reacts with FeCl3 to yield a yellow precipitate which upon recrystallization from DMSO/CH2Cl2 gives red crystals of the octanuclear iron(III) complex [{FeIIICl(H2-1)}4FeIII4(μ4-O)4Cl4] 2 ・ 4CH2Cl2 containing a central Fe4(μ4-O)4 cubane core. Crystals of 2 ・4DMF were obtained by slow oxidation of the green iron(II) complex obtained from ferrous chloride and Na2(H2-1) after recrystallization from DMF. The structure determination of 2 ・4CH2Cl2 also revealed the presence of the iron(III) oxo cubane core. The core is surrounded by four iron atoms each coordinated by η4-(H2-1)2- and Cl- ligands.

Polygonal Approximation Method in the Hodograph Plane

1949 ◽  
Vol 16 (2) ◽  
pp. 123-133
Author(s):  
H. Poritsky
Keyword(s):  
Fluid Flow ◽  
Approximation Method ◽  
Applied Mechanics ◽  
Polygonal Approximation ◽  
Physical Plane ◽  
Flow Equations ◽  
Hodograph Plane ◽  
Superposition Of Solutions ◽  
Sixth International

Abstract This paper extends the discussion of the approximate method of integrating the equations of compressible fluid flow in the hodograph plane first presented by the author before the Sixth International Congress of Applied Mechanics, Paris, France, September, 1948. As an introduction to the discussion of the polygonal approximation method, fundamental fluid-flow equations are reviewed briefly. Determination of the flow function ψ by the “Method of Reflections” is described and an application of the method illustrated. How flow in the physical plane can be determined by superposition of solutions discussed is shown for the simpler incompressible case.

Application of spherical Slepian functions to the inversion of virtual observatory satellite magnetic data into localised regions of flow on the core-mantle boundary

2021 ◽  
Author(s):  
Hannah Rogers ◽  
Ciaran Beggan ◽  
Kathryn Whaler
Keyword(s):  
Spherical Surface ◽  
Surface Flow ◽  
Magnetic Data ◽  
Virtual Observatory ◽  
Core Surface ◽  
Flow Models ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
The Core ◽  
Slepian Functions

<p>Spherical Slepian functions (or ‘Slepian functions’) are mathematical functions which can be used to decompose potential fields, as represented by spherical harmonics, into smaller regions covering part of a spherical surface. This allows a spatio-spectral trade-off between aliasing of the signal at the boundary edges while constraining it within a region of interest. While Slepian functions have previously been applied to geodetic and crustal magnetic data, this work further applies Slepian functions to flows on the core-mantle boundary. There are two main reasons for restricting flow models to certain parts of the core surface. Firstly, we have reason to believe that different dynamics operate in different parts of the core (such as under LLSVPs) while, secondly, the modelled flow is ambiguous over certain parts of the surface (when applying flow assumptions). Spherical Slepian functions retain many of the advantages of our usual flow description, concerning for example the boundary conditions it must satisfy, and allowing easy calculation of the power spectrum, although greater initial computational effort is required.</p><p><br>In this work, we apply Slepian functions to core flow models by directly inverting from satellite virtual observatory magnetic data into regions of interest. We successfully demonstrate the technique and current short comings by showing whole core surface flow models, flow within a chosen region, and its corresponding complement. Unwanted spatial leakage is generated at the region edges in the separated flows but to less of an extent than when using spherical Slepian functions on existing flow models. The limited spectral content we can infer for core flows is responsible for most, if not all, of this leakage. Therefore, we present ongoing investigations into the cause of this leakage, and to highlight considerations when applying Slepian functions to core surface flow modelling.</p>

D-C Network-Analyzer Determination of Fluid-Flow Pattern in a Centrifugal Impeller

1947 ◽  
Vol 14 (2) ◽  
pp. A113-A118
Author(s):  
C. Concordia ◽  
G. K. Carter
Keyword(s):  
Fluid Flow ◽  
Flow Pattern ◽  
Arbitrary Shape ◽  
Centrifugal Impeller ◽  
Network Analyzer ◽  
Two Dimensional ◽  
Special Shape ◽  
Electrical Method ◽  
Incompressible Ideal Fluid

Abstract The objects of this paper are, first, to describe an electrical method of determining the flow pattern for the flow of an incompressible ideal fluid through a two-dimensional centrifugal impeller, and second, to present the results obtained for a particular impeller. The method can be and has been applied to impellers with blades of arbitrary shape, as distinguished from analytical methods which can be applied directly only to blades of special shape (1).

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