Satellite Motion in a Manev Potential with Drag

In this paper, we consider a satellite orbiting in a Manev gravitational potential under the influence of an atmospheric drag force that varies with the square of velocity. Using an exponential atmosphere that varies with the orbital altitude of the satellite, we examine a circular orbit scenario. In particular, we derive expressions for the change in satellite radial distance as a function of the drag force parameters and obtain numerical results. The Manev potential is an alternative to the Newtonian potential that has a wide variety of applications, in astronomy, astrophysics, space dynamics, classical physics, mechanics, and even atomic physics.Comment: Accepted for publication in Astrophysics and Space Scienc

Number of Information and its Relation to the Cosmological Constant Resulting from Landauer’s Principle

Using a recent published formula for the number of information N that results from Landauer’s principle we obtain an expression for the cosmological constant Λ . Next, assuming the universe as a system of mass M satisfying Landauer’s principle and eliminating its mass M from the given expression for the number of information, we obtain a new expression that agrees with the one derived by Lloyd. Furthermore, we modify the generalized entropy relation and three equivalent entropy expressions are obtained. Finally, in two different universes the time rate of change of the entropy is calculated. In a flat universe the time rate of the entropy is time independent and depends on fundamental constants of physics

The Role of Turbulence and Magnetic Fields in Simulated Filamentary Structure

We use numerical simulations of turbulent cluster-forming regions to study the nature of dense filamentary structures in star formation. Using four hydrodynamic and magnetohydrodynamic simulations chosen to match observations, we identify filaments in the resulting column density maps and analyze their properties. We calculate the radial column density profiles of the filaments every 0.05 Myr and fit the profiles with the modified isothermal and pressure confined isothermal cylinder models, finding reasonable fits for either model. The filaments formed in the simulations have similar radial column density profiles to those observed. Magnetic fields provide additional pressure support to the filaments, making `puffier' filaments less prone to fragmentation than in the pure hydrodynamic case, which continue to condense at a slower rate. In the higher density simulations, the filaments grow faster through the increased importance of gravity. Not all of the filaments identified in the simulations will evolve to form stars: some expand and disperse. Given these different filament evolutionary paths, the trends in bulk filament width as a function of time, magnetic field strength, or density, are weak, and all cases are reasonably consistent with the finding of a constant filament width in different star-forming regions. In the simulations, the mean FWHM lies between 0.06 and 0.26 pc for all times and initial conditions, with most lying between 0.1 to 0.15 pc; the range in FWHMs are, however, larger than seen in typical Herschel analyses. Finally, the filaments display a wealth of substructure similar to the recent discovery of filament bundles in Taurus.Comment: 18 pages, 8 figures, 7 tables. Accepted for publication in Ap

Depression and self -silencing in lesbian and heterosexual women

Depression among lesbians is an underexplored area in the literature of the psychology of women and in depression research. A few investigators have hypothesized about the factors that place lesbians at risk for depression, and have explored those hypotheses experimentally. However, there is a large gap in the understanding of lesbians and depression. Dana Jack (1991) proposed a model of depression which holds that women who fail to represent their experiences to romantic partners are at increased risk for depression. One hundred and seventy participants were recruited to test this model (85 lesbians and 71 heterosexual women, as well as 14 bisexual women who were included in the demographics but otherwise excluded) using Jack\u27s Silencing the Self Scale, the Beck Depression Inventory, and a demographic questionnaire. Lesbians were also asked to complete Cass\u27 Stage Allocation Measure. An additional 11 subjects failed to complete the BDI and so were excluded from all analyses involving that test. It was found that the lesbian sample was more self-silenced than the heterosexual group, but there was no difference in the level of depression between groups. A three-way ANOVA revealed significant differences between stage of coming out and self-silencing as well as stage of coming out and depression. Several explanations were offered for the unexpected finding of increased self-silencing among lesbians. Further research is needed to better elucidate self-silencing in lesbians, as well as the experience of depression in lesbians

Mathematical Aspects of Image Processing

In this thesis, image processing is explored from a mathematical point of view. After defining a digitized image, techniques for adjusting resolution are discussed. Image transformations defined on a neighborhood centered about a pixel and their relationships to convolution are considered. The Fourier transform and the discrete Fourier transform are introduced in both one and two dimensions. Properties of the Fourier transform are demonstrated with analysis of the power spectrum of an image. A degradation model is used to study image restoration, in the cases where distortion is due to noise and motion blur. Other approaches to image restoration employ the processes of inverse and Wiener filtering.  M.A