Origin of Disc Lopsidedness in the Eridanus Group of Galaxies

The HI surface density maps for a sample of 18 galaxies in the Eridanus group are Fourier analysed. This analysis gives the radial variation of the lopsidedness in the HI spatial distribution. The lopsidedness is quantified by the Fourier amplitude $A_1$ of the $m=1$ component normalized to the average value. It is also shown that in the radial region where the stellar disc and HI overlap, their $A_1$ coefficients are comparable. All the galaxies studied show significant lopsidedness in HI. The mean value of $A_1$ in the inner regions of the galaxies (1.5 - 2.5 scale lengths) is $\geq 0.2$. This value of $A_1$ is twice the average value seen in the field galaxies. Also, the lopsidedness is found to be smaller for late-type galaxies, this is opposite to the trend seen in the field galaxies. These two results indicate a different physical origin for disc lopsidedness in galaxies in a group environment compared to the field galaxies. Further, a large fraction ($\sim$ 30%) shows a higher degree of lopsidedness ($A_1 \geq 0.3$). It is also seen that the disk lopsidedness increases with the radius as demonstrated in earlier studies, but over a radial range that is two timeslarger than done in the previous studies. The average lopsidedness of the halo potential is estimated to be $\sim 10$%, assuming that the lopsidedness in HI disc is due to its response to the halo asymmetry.Comment: 10 pages, 5 figures, Accepted for publication in MNRA

Self-Consistent Response of a Galactic Disk to an Elliptical Perturbation Halo Potential

We calculate the self-consistent response of an axisymmetric galactic disk perturbed by an elliptical halo potential of harmonic number m = 2, and obtain the net disk ellipticity. Such a potential is commonly expected to arise due to a galactic tidal encounter and also during the galaxy formation process. The self-gravitational potential corresponding to the self-consistent, non-axisymmetric density response of the disk is obtained by inversion of Poisson equation for a thin disk. This response potential is shown to oppose the perturbation potential, because physically the disk self-gravity resists the imposed potential. This results in a reduction in the net ellipticity of the perturbation halo potential in the disk plane. The reduction factor denoting this decrease is independent of the strength of the perturbation potential, and has a typical minimum value of 0.75 - 0.9 for a wide range of galaxy parameters. The reduction is negligible at all radii for higher harmonics (m > or = 3) of the halo potential. (abridged).Comment: 26 pages (LaTex- aastex style), 3 .eps figures. To appear in the Astrophysical Journal, Vol. 542, Oct. 20, 200

A Magellanic Origin for the Warp of the Galaxy

We show that a Magellanic Cloud origin for the warp of the Milky Way can explain most quantitative features of the outer HI layer recently identified by Levine, Blitz & Heiles (2005). We construct a model similar to that of Weinberg (1998) that produces distortions in the dark matter halo, and we calculate the combined effect of these dark-halo distortions and the direct tidal forcing by the Magellanic Clouds on the disk warp in the linear regime. The interaction of the dark matter halo with the disk and resonances between the orbit of the Clouds and the disk account for the large amplitudes observed for the vertical m=0,1,2 harmonics. The observations lead to six constraints on warp forcing mechanisms and our model reasonably approximates all six. The disk is shown to be very dynamic, constantly changing its shape as the Clouds proceed along their orbit. We discuss the challenges to MOND placed by the observations.Comment: 4 pages, 3 figures, submitted to ApJ Letters. Additional graphics, 3d visualizations and movies available at http://www.astro.umass.edu/~weinberg/lm

Plant Communities of Highland Heights Community Park, Cuyahoga County, Ohio

Author Institution: Dept of Biological, Geological & Environmental Sciences, Cleveland State University, Cleveland, OHAuthor Institution: Dept of Biology, John Carroll University, University Heights, OHAuthor Institution: Normandeau Associates, Bedford, NHWe have described the vegetation structure with respect to various community types of Highland Heights Community Park and adjoining territory. High values of Shannon’s Diversity Indexes and Floristic Quality Assessment Indexes indicate a superior quality, species-rich habitat with several high-fidelity species. Based on our research, which reveals that the study site is worthy of conservation and preservation, we suggest recommendations to the city of Highland Heights for park management and land use planning

Healthcare technology, patient engagement and adherence : systems and business opportunity analysis

Thesis (S.M. in Management and Engineering)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 63-64).In the current shift in the US healthcare system, lower cost, higher quality of care, access and safety are the main drivers that are effecting changes. Patient compliance with medication and technology enabled wellness and engagement programs play an important role in ensuring the cost and quality of care is reduced. In a recent study, the overall cost of poor medication adherence, measured in otherwise avoidable medical spending, is close to $310 billion annually, representing approximately 14% of total healthcare expenditures. There have been several studies analyzing the reasons for and impact of non-adherence and solutions to achieve increasing compliance. With the recent wave in healthcare technology, the scope of prescription medication adherence needs to be expanded to include patient engagement and their awareness towards lifestyle changes and managing their own health. This thesis engages in an analysis of these compliance issues and in understanding the relationships among the various stakeholders involved. It also analyses the several technology platforms and solutions from mobile health to "gamification" and social networks from a business, user and regulatory standpoint. It looks into how these newer health technologies helps the individual in adhering and realizing novel insights into their own patterns related to medication, lifestyle and general health. Further, working with a health technology startup catering to the behavioral care market, a real world application of a health technology product that utilizes technology based patient assessment, decision support and patient communication, will be evaluated to explore how it will help in delivering value to several stakeholders.by Chetan R. Jog.S.M.in Management and Engineerin

Spatial and Kinematical Lopsidedness of Atomic Hydrogen in the Ursa Major Group of Galaxies

We have carried out the harmonic analysis of the atomic hydrogen (HI) surface density maps and the velocity fields for 11 galaxies belonging to the Ursa Major group, over a radial range of 4-6 disc scalelengths in each galaxy. This analysis gives the radial variation of spatial lopsidedness, quantified by the Fourier amplitude A$_1$ of the m=1 component normalised to the average value. The kinematical analysis gives a value for the elongation of the potential to be $\sim 10$. The mean amplitude of spatial lopsidedness is found to be $\sim 0.14$ in the inner disc, similar to the field galaxies, and is smaller by a factor of $\sim 2$ compared to the Eridanus group galaxies. It is also shown that the the average value of A$_1$ does not increase with the Hubble type, contrary to what is seen in field galaxies. We argue that the physical origin of lopsidedness in the Ursa Major group of galaxies is tidal interactions, albeit weaker and less frequent than in Eridanus. Thus systematic studies of lopsidedness in groups of galaxies can provide dynamical clues regarding the interactions and evolution of galaxies in a group environment.Comment: 12 pages, 7 figures, 3 tables. Accepted for publication by MNRA

Mixed lattice phases in cold dense matter

Over a wide density range, the ground state of cold neutral matter in the absence of external magnetic fields is a degenerate sea of electrons containing a lattice of nuclei. In certain density regions, a phase composed of interpenetrating cubic lattices of different nuclides is preferable to a body-centered cubic lattice of any single nuclide. The arguments supporting this result are first made assuming the electrons to be a uniform background; the qualitative features remain when screening and exchange effects are included