The Three‐dimensional Structure of the Warm Local Interstellar Medium. II. The Colorado Model of the Local Interstellar Cloud

&#160;We describe the very local interstellar medium (VLISM) immediately outside of the outer heliosphere. The VLISM consists&#160; of four partially ionized clouds - the Local Interstellar Cloud (LIC),&#160; G cloud, Blue cloud, and Aql cloud that are in contact with the outer&#160; heliosphere, and ionized gas produced by extreme-UV radiation&#160; primarily from the star Epsilon CMa. We construct the&#160; three-dimensional shape of the LIC based on interstellar line&#160; absorption along 62 sightlines and show that in the direction of&#160; Epsilon CMa, Beta CMa, and Sirius B the neutral hydrogen column&#160; density from the center of the LIC looking outward is a minimum.&#160; We call this region the ``hydrogen hole''. In this direction, the&#160; presence of Blue cloud absorption and the absence of LIC absorption&#160; can be simply explained by the Blue cloud lying just outside of the&#160; heliosphere. We propose that the outer edge of the Blue cloud is a&#160; Str\"omgren shell driven toward the heliosphere by high pressures in&#160; the H II region. The outer edges of other clouds facing Epsilon CMa&#160; are likely also Stromgren shells. Unlike previous models, the LIC surrounds less than half of the heliosphere.We find that the vectors of neutral and ionized helium flowing through the heliosphere are inconsistent with the mean LIC flow&#160; vector and describe several possible explanations. The ionization of nearby intercloud gas is consistent with photo-ionization by&#160; Epsilon CMa and hot white dwarfs without requiring additional&#160; sources of ionization or million degree plasma. In the upwind&#160; direction, the heliosphere is passing through an environment of&#160; several LISM clouds, which may explain the recent influx of&#160; interstellar grains containing 60Fe from supernova ejecta measured&#160; in Antarctica snow. The Sun will leave the outer partof the LIC&#160; in less than 1900 years, perhaps this year, to either enter the&#160; partially ionized G cloud or a highly ionized intercloud layer.&#160; The heliosphere will change in either scenario. An instrumented&#160; deep space probe sending back in situ plasma and magnetic field&#160; measurements from 500-1,000 AU is needed to understand the&#160; heliosphere environment rather than integrated data along the&#160; sightlines to stars. &#160;

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Components of the Local Interstellar Medium

Symposium - International Astronomical Union ◽

10.1017/s007418090022007x ◽

2001 ◽

Vol 203 ◽

pp. 595-598

Author(s):

J. L. Linsky ◽

S. Redfield ◽

B. Wood

Keyword(s):

Interstellar Medium ◽

Critical Velocity ◽

Column Density ◽

Interstellar Cloud ◽

The Sun ◽

Local Interstellar Medium ◽

Density Data ◽

Local Interstellar Cloud

HST, EUVE, and Ca II spectra are providing critical velocity and column density data needed to identify individual stuctures (clouds) of warm gas in the local ISM. The Sun is located very close to the edge of and will soon leave the Local Interstellar Cloud (LIC). We will summarize the properties of the LIC and other nearby warm clouds.

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The Three-dimensional structure of frozen-hydrated nudaurelia capensis β virus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127682 ◽

1987 ◽

Vol 45 ◽

pp. 650-651

Author(s):

N. H. Olson ◽

T. S. Baker ◽

Wu Bo Mu ◽

J. E. Johnson ◽

D. A. Hendry

Keyword(s):

South African ◽

Rna Virus ◽

Carbon Film ◽

Three Dimensional ◽

Dimensional Structure ◽

Electron Dose ◽

Total Electron ◽

Three Dimensional Structure ◽

Negative Stain ◽

Dimensional Reconstruction

Nudaurelia capensis β virus (NβV) is an RNA virus of the South African Pine Emperor moth, Nudaurelia cytherea capensis (Lepidoptera: Saturniidae). The NβV capsid is a T = 4 icosahedron that contains 60T = 240 subunits of the coat protein (Mr = 61,000). A three-dimensional reconstruction of the NβV capsid was previously computed from visions embedded in negative stain suspended over holes in a carbon film. We have re-examined the three-dimensional structure of NβV, using cryo-microscopy to examine the native, unstained structure of the virion and to provide a initial phasing model for high-resolution x-ray crystallographic studiesNβV was purified and prepared for cryo-microscopy as described. Micrographs were recorded ∼1 - 2 μm underfocus at a magnification of 49,000X with a total electron dose of about 1800 e-/nm2.

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Three Dimensional structure and organization of diploid chromosomes by optical section microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127608 ◽

1987 ◽

Vol 45 ◽

pp. 633-635

Author(s):

David A. Agard ◽

Yasushi Hiraoka ◽

John W. Sedat

Keyword(s):

Dimensional Space ◽

Three Dimensional ◽

Developmental State ◽

Mitotic Cell ◽

Biological Properties ◽

Dimensional Structure ◽

Specific Gene ◽

Three Dimensional Structure ◽

Complementary Techniques ◽

Dynamic Structures

In an effort to understand the complex relationship between structure and biological function within the nucleus, we have embarked on a program to examine the three-dimensional structure and organization of Drosophila melanogaster embryonic chromosomes. Our overall goal is to determine how DNA and proteins are organized into complex and highly dynamic structures (chromosomes) and how these chromosomes are arranged in three dimensional space within the cell nucleus. Futher, we hope to be able to correlate structual data with such fundamental biological properties as stage in the mitotic cell cycle, developmental state and transcription at specific gene loci.Towards this end, we have been developing methodologies for the three-dimensional analysis of non-crystalline biological specimens using optical and electron microscopy. We feel that the combination of these two complementary techniques allows an unprecedented look at the structural organization of cellular components ranging in size from 100A to 100 microns.

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Three-Dimensional Structure of Cloned T3 Connector Protein at 1.6nm Resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180161 ◽

1990 ◽

Vol 48 (1) ◽

pp. 282-283

Author(s):

José L. Carrascosa ◽

José M. Valpuesta ◽

Hisao Fujisawa

Keyword(s):

Dna Sequences ◽

Expression Vector ◽

Three Dimensional ◽

Deae Cellulose ◽

Dna Packaging ◽

Dimensional Structure ◽

Two Dimensional ◽

Freezing And Thawing ◽

Three Dimensional Structure ◽

Dimensional Reconstruction

The head to tail connector of bacteriophages plays a fundamental role in the assembly of viral heads and DNA packaging. In spite of the absence of sequence homology, the structure of connectors from different viruses (T4, Ø29, T3, P22, etc) share common morphological features, that are most clearly revealed in their three-dimensional structure. We have studied the three-dimensional reconstruction of the connector protein from phage T3 (gp 8) from tilted view of two dimensional crystals obtained from this protein after cloning and purification.DNA sequences including gene 8 from phage T3 were cloned, into Bam Hl-Eco Rl sites down stream of lambda promotor PL, in the expression vector pNT45 under the control of cI857. E R204 (pNT89) cells were incubated at 42°C for 2h, harvested and resuspended in 20 mM Tris HC1 (pH 7.4), 7mM 2 mercaptoethanol, ImM EDTA. The cells were lysed by freezing and thawing in the presence of lysozyme (lmg/ml) and ligthly sonicated. The low speed supernatant was precipitated by ammonium sulfate (60% saturated) and dissolved in the original buffer to be subjected to gel nitration through Sepharose 6B, followed by phosphocellulose colum (Pll) and DEAE cellulose colum (DE52). Purified gp8 appeared at 0.3M NaCl and formed crystals when its concentration increased above 1.5 mg/ml.

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