Appendix - Some spectroscopic observations of the interaction between a plasma wind and a dipole magnetic field

Spectroscopic studies on seeded plasma interaction with magnetic dipole fiel

Expansivity and Shadowing in Linear Dynamics

In the early 1970's Eisenberg and Hedlund investigated relationships between expansivity and spectrum of operators on Banach spaces. In this paper we establish relationships between notions of expansivity and hypercyclicity, supercyclicity, Li-Yorke chaos and shadowing. In the case that the Banach space is $c_0$ or $\ell_p$ ($1 \leq p < \infty$), we give complete characterizations of weighted shifts which satisfy various notions of expansivity. We also establish new relationships between notions of expansivity and spectrum. Moreover, we study various notions of shadowing for operators on Banach spaces. In particular, we solve a basic problem in linear dynamics by proving the existence of nonhyperbolic invertible operators with the shadowing property. This also contrasts with the expected results for nonlinear dynamics on compact manifolds, illuminating the richness of dynamics of infinite dimensional linear operators

Anisotropy of the space orientation of radio sources. I: The catalog

A catalog of the extended extragalactic radio sources consisting of 10461 objects is compiled based on the list of radio sources of the FIRST survey. A total of 1801 objects are identified with galaxies and quasars of the SDSS survey and the Veron-Veron catalog. The distribution of the position angles of the axes of radio sources from the catalog is determined, and the probability that this distribution is equiprobable is shown to be less then 10^(-7). This result implies that at Z equal to or smaller then 0.5, spatial orientation of the axes of radio sources is anisotropic at a statistically significant level.Comment: 8 pages, 7 figure

Analysis of light gage steel shear diaphragms

INTRODUCTION It has long been recognized by structural engineers, that light gage steel cladding floor and roof decking systems have a considerable stiffening and strengthening effect on building frameworks. The beneficial contribution of these diaphragm systems is most pronounced when the structure as a whole is subjected to loads which result in an in-plane shear action of the cladding. This occurs, for example, when the rigidity of a floor or roof diaphragm acting as a membrane is utilized to transmit lateral forces to stiff end walls. Another example of diaphragm action is found in pitched roof portal sheds under vertical and lateral loads. In such cases the membrane strength and rigidity of the cladding can be used to restrict the tendency of intermediate frames to sway, by transfering the load to end walls and resulting in substantial economy in the design of the frames. Specific utilization of the in-plane shear strength and stiffness of panelling was suggested more than 18 years ago, but unless this effect could be calculated in advance no practical use could be made. In order to take this contribution to stiffness and strength into account in engineering design, it was necessary to develop means for predicting the effective shear rigidity and ultimate strength in shear of the steel panel diaphragm. Because of the complexity of such diaphragm systems, up to now, engineers have relied upon tests of full-scale-panel assemblies, in which the performance of specific combinations of panels, marginal framing members and connections have been studied on a strictly ad hoc basis. While much has been learned using this approach, and valuable design information was obtained, no rational theory to describe and predict structural behavior has resulted. On the other hand, testing of large full scale diaphragm installations is expensive and time consuming, and tests results are applicable only to identical assembly using the same panels as tested, with directly equivalent fastening systems. The need for a general method of analysis is clear

Analysis of light gage steel shear diaphragms

INTRODUCTION: It has long been recognized by structural engineers, that light gage steel cladding floor and roof decking systems have a considerable stiffening and strengthening effect on building frameworks. The beneficial contribution of these diaphragm systems is most pronounced when the structure as a whole is subjected to loads which result in an in-plane shear action of the cladding. This occurs, for example, when the rigidity of a floor or roof diaphragm acting as a membrane is utilized to transmit lateral forces to stiff end walls. Another example of diaphragm action is found in pitched roof portal sheds under vertical and lateral loads. In such cases the membrane strength and rigidity of the cladding can be used to restrict the tendency of intermediate frames to sway, by transfering the load to end walls and resulting in substantial economy in the design of the frames. Specific utilization of the in-plane shear strength and stiffness of panelling was suggested more than 18 years ago, but unless this effect could be calculated in advance no practical use could be made. In order to take this contribution to stiffness and strength into account in engineering design, it was necessary to develop means for predicting the effective shear rigidity and ultimate strength in shear of the steel panel diaphragm. Because of the complexity of such diaphragm systems, up to now, engineers have relied upon tests of full-scale-panel assemblies, in which the performance of specific combinations of panels, marginal framing members and connections have been studied on a strictly ad hoc basis. While much has been learned using this approach, and valuable design information was obtained, no rational theory to describe and predict structural behavior has resulted. On the other hand, testing of large full scale diaphragm installations is expensive and time consuming, and tests results are applicable only to identical assembly using the same panels as tested, with directly equivalent fastening systems. The need for a general method of analysis is clear

Analysis of light gage steel shear diaphragms

INTRODUCTION: It has long been recognized by structural engineers, that light gage steel cladding floor and roof decking systems have a considerable stiffening and strengthening effect on building frameworks. The beneficial contribution of these diaphragm systems is most pronounced when the structure as a whole is subjected to loads which result in an in-plane shear action of the cladding. This occurs, for example, when the rigidity of a floor or roof diaphragm acting as a membrane is utilized to transmit lateral forces to stiff end walls. Another example of diaphragm action is found in pitched roof portal sheds under vertical and lateral loads. In such cases the membrane strength and rigidity of the cladding can be used to restrict the tendency of intermediate frames to sway, by transfering the load to end walls and resulting in substantial economy in the design of the frames. Specific utilization of the in-plane shear strength and stiffness of panelling was suggested more than 18 years ago, but unless this effect could be calculated in advance no practical use could be made. In order to take this contribution to stiffness and strength into account in engineering design, it was necessary to develop means for predicting the effective shear rigidity and ultimate strength in shear of the steel panel diaphragm. Because of the complexity of such diaphragm systems, up to now, engineers have relied upon tests of full-scale-panel assemblies, in which the performance of specific combinations of panels, marginal framing members and connections have been studied on a strictly ad hoc basis. While much has been learned using this approach, and valuable design information was obtained, no rational theory to describe and predict structural behavior has resulted. On the other hand, testing of large full scale diaphragm installations is expensive and time consuming, and tests results are applicable only to identical assembly using the same panels as tested, with directly equivalent fastening systems. The need for a general method of analysis is clear

VV124 (UGC4879): A new transitional dwarf galaxy in the periphery of the Local Group

We present the first resolved-star photometry of VV124 (UGC4879) and find that this is the most isolated dwarf galaxy in the periphery of the Local Group. Based on imaging and spectroscopic follow up observations with the 6m BTA telescope, we resolve VV124 into 1560 stars down to the limiting magnitude levels of V~25.6 and I~23.9. The young blue stellar populations and emission gas are found near the core, but noticeably displaced from the center of the galaxy as traced by dominant evolved red stars. The mean radial velocity derived from the spectra of two Blue Supergiant stars, an HII region and unresolved continuum sources is -80+/-10 km/s. The evolved ``red tangle'' stellar populations, which contains the red giant branch (RGB), are identified at large galactocentric radii. We use the I-band luminosity function to determine the distance based on the Tip of RGB method, 1.1+/-0.1 Mpc. This is ~10 times closer than the values usually assumed in the literature, and we provide revised distance dependent parameters. From the mean (V-I) color of the RGB, we estimate the mean metallicity as [Fe/H]~-1.37 dex. Despite of its isolated location, the properties of VV124 are clearly not those of a galaxy in formation, but rather similar to a transitional dIrr/dSph type.Comment: 4 pages, submitted to MNRAS Letter

The HI Content of Compact Groups of Galaxies

The HI content of Hickson Compact Groups in the southern hemisphere is measured using data from the HI Parkes All Sky Survey (HIPASS), and dedicated observations using the narrowband filter on the Multibeam instrument on the Parkes telescope. The expected HI mass of these groups was estimated using the luminosity, diameter and morphological types of the member galaxies, calibrated from published data. Taking careful account of non-detection limits, the results show that the compact group population that has been detected by these observations has an HI content similar to that of galaxies in the reference field sample. The upper limits for the undetected groups lie within the normal range; improvement of these limits will require a large increase in sensitivity.Comment: 27 pages, 5 figures. Accepted for publication in PAS

On the Relation Between Peak Luminosity and Parent Population of Type Ia Supernovae: A New Tool for Probing the Ages of Distant Galaxies

We study the properties of Type Ia Supernovae (SNe Ia) as functions of the radial distance from their host galaxy centers. Using a sample of 62 SNe Ia with reliable luminosity, reddening, and decline rate determinations, we find no significant radial gradients of SNe Ia peak absolute magnitudes or decline rates in elliptical+S0 galaxies, suggesting that the diversity of SN properties is not related to the metallicity of their progenitors. We do find that the range in brightness and light curve width of supernovae in spiral galaxies extends to brighter, broader values. These results are interpreted as support for an age, but not metallicity, related origin of the diversity in SNe Ia. If confirmed with a larger and more accurate sample of data, the age-luminosity relation would offer a new and powerful tool to probe the ages and age gradients of stellar populations in galaxies at redshift as high as $z\sim1-2$. The absence of significant radial gradients in the peak $\rm (B-V)_0$ and $\rm (V-I)_0$ colors of SNe Ia supports the redding correction method of Phillips et al (1999). We find no radial gradient in residuals from the SN Ia luminosity-width relation, suggesting that the relation is not affected by properties of the progenitor populations and supporting the reliability of cosmological results based upon the use of SNe Ia as distance indicators.Comment: 19 pages, incl. 3 tables & 3 figures; to appear in Nov 2000 issue of Ap

Longitudinal Ion Acceleration from High-Intensity Laser Interactions with Underdense Plasma

Longitudinal ion acceleration from high-intensity (I ~ 10^20 Wcm^-2) laser interactions with helium gas jet targets (n_e ~ 0.04 n_c) have been observed. The ion beam has a maximum energy for He^2+ of approximately 40 MeV and was directional along the laser propagation path, with the highest energy ions being collimated to a cone of less than 10 degrees. 2D particle-in-cell simulations have been used to investigate the acceleration mechanism. The time varying magnetic field associated with the fast electron current provides a contribution to the accelerating electric field as well as providing a collimating field for the ions. A strong correlation between the plasma density and the ion acceleration was found. A short plasma scale-length at the vacuum interface was observed to be beneficial for the maximum ion energies, but the collimation appears to be improved with longer scale-lengths due to enhanced magnetic fields in the ramp acceleration region.Comment: 18 pages, 6 figure