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

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

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

Ecology of ficus religiosa accounts for its association with religion

While many plants and trees in specific areas acquire cult significance, very few such as Ficus religiosa L. have acquired a universal status. This hemiepiphyte, Ficus religiosa L., is of dual interest since it venerated by a quarter of the present mankind (Hindus and Buddhists, largely Asian) on one hand and also since these plants are blamed for destruction of buildings due to their ability to grow on buildings. Divergence in views exists whether epiphytic plants exert a destructive influence on buildings. A focused survey of the coastal forts on land and sea has shown uniformly that the naturally growing plants of certain Ficus sp., notably Ficus religiosa L., grow exclusively on the vertical sheer side of rock faces and not either on the ground or on the top surface of these 8-10 centuries old rock structures; also seen on the side of rock piles as recent as 4-5 years as well as in sacred groves of several centuries to millennia old. We could trace the roots through these structures from beginning to the end in many parts of these forts, especially when there are overhanging structures at entrances. The root tips, the point of growth, would be far too insignificant to account for destruction in any of these large rock-and-lime masonry structures while vibration per se was insignificant as the tree was seen in all forts on land or sea. The association with religion of the distinctive Ficus religiosa itself appears to be self-evident from its socio-anthropological association with rock piles, hitherto not visualized for any flora and logically appears to pre-date both Hinduism and Buddhism

Implementation of Classification Technique for Mammogram Image

Abstract: Mammography is an important research field. Mammography Image classification is an area of interest to most of the researchers today. The aim of this paper is to detect the Mammography image for its malignancy. Different methods can be used to detect the malignancy. This paper represents GLDM feature extraction method and SVM classifier. Experiments were conducted on MIAS database. The results show that combination of GLDM feature extractor with SVM classifier is found to give appropriate results

Patterns in abundance and diversity of faecally dispersed parasites of tiger in Tadoba National Park, central India

BACKGROUND: Importance of parasites in ecological and evolutionary interactions is being increasingly recognized. However, ecological data on parasites of important host species is still scanty. We analyze the patterns seen in the faecal parasites of tigers in the Tadoba National Park, India, and speculate on the factors and processes shaping the parasite community and the possible implications for tiger ecology. RESULTS: The prevalence and intensities were high and the parasite community was dominated by indirect life cycle parasites. Across all genera of parasites variance scaled with the square of the mean and there was a significant positive correlation between prevalence and abundance. There was no significant association between different types of parasites. CONCLUSIONS: The 70 samples analyzed formed 14 distinct clusters. If we assume each of the clusters to represent individual tigers that were sampled repeatedly and that resident tigers are more likely to be sampled repeatedly, the presumed transient tigers had significantly greater parasite loads than the presumed resident ones

Global Star Formation Rates in Disk Galaxies and Circumnuclear Starbursts from Cloud Collisions

We invoke star formation triggered by cloud-cloud collisions to explain global star formation rates of disk galaxies and circumnuclear starbursts. Previous theories based on the growth rate of gravitational perturbations ignore the dynamically important presence of magnetic fields. Theories based on triggering by spiral density waves fail to explain star formation in systems without such waves. Furthermore, observations suggest gas and stellar disk instabilities are decoupled. Following Gammie, Ostriker & Jog (1991), the cloud collision rate is set by the shear velocity of encounters with initial impact parameters of a few tidal radii, due to differential rotation in the disk. This, together with the effective confinement of cloud orbits to a two dimensional plane, enhances the collision rate above that for particles in a three dimensional box. We predict Sigma_{SFR}(R) proportional to Sigma_{gas} Omega (1-0.7 beta). For constant circular velocity (beta = 0), this is in agreement with recent observations (Kennicutt 1998). We predict a B-band Tully-Fisher relation: L_{B} proportional to v_{circ}^{7/3}, also consistent with observations. As additional tests, we predict enhanced star formation in regions with relatively high shear rates, and lower star formation efficiencies in clouds of higher mass.Comment: 27 pages including 3 figures and 2 tables. Accepted to ApJ. Expanded statistical analysis of cloud SF efficiency test. Stylistic changes. Data for figures available electronically at http://astro.berkeley.edu/~jt/disksfr.htm

Rotating Nuclear Rings and Extreme Starbursts in Ultraluminous Galaxies

New high resolution interferometer data of 10 IR ultraluminous galaxies shows the molecular gas is in rotating nuclear rings or disks with radii 300 to 800 pc. Most of the CO flux comes from a moderate-density, warm, intercloud medium rather than self-gravitating clouds. Gas masses of ~ 5 x 10^9 Msun, 5 times lower than the standard method are derived from a model of the molecular disks. The ratio of molecular gas to dynamical mass, is M_gas/M_dyn ~ 1/6 with a maximum ratio of gas to total mass surface density of 1/3. For the galaxies VIIZw31, Arp193, and IRAS 10565+24, there is good evidence for rotating molecular rings with a central gap. In addition to the rotating rings a new class of star formation region is identified which we call an Extreme Starburst. They have a characteristic size of only 100 pc., about 10^9 Msun of gas and an IR luminosity of ~3 x 10^11 Lsun. Four extreme starbursts are identified in the 3 closest galaxies in the sample Arp220, Arp193 and Mrk273. They are the most prodigious star formation events in the local universe, each representing about 1000 times as many OB stars as 30 Doradus. In Arp220, the CO and 1.3 mm continuum maps show the two ``nuclei'' embedded in a central ring or disk and a fainter structure extending 3 kpc to the east, normal to the nuclear disk. There is no evidence that these sources really are the pre-merger nuclei. They are compact, extreme starburst regions containing 10^9 Msun of dense molecular gas and new stars, but no old stars. Most of the dust emission and HCN emission arises in the two extreme starbursts. The entire bolometric luminosity of Arp~220 comes from starbursts, not an AGN. In Mrk231, the disk geometry shows that the molecular disk cannot be heated by the AGN; the far IR luminosity of Mrk~231 is powered by a starburst, not the AGN. (Abridged)Comment: 97 pages Latex with aasms.sty, including 29 encapsulated Postscript figures. Figs 18 and 23 are GIFs. 31 figures total. Text and higher quality versions of figures available at http://sbastk.ess.sunysb.edu/www/RINGS_ESB_PREPRINT.html To be published in Ap. J., 10 Nov. 199

RS-Net: Regression-Segmentation 3D CNN for Synthesis of Full Resolution Missing Brain MRI in the Presence of Tumours

Accurate synthesis of a full 3D MR image containing tumours from available MRI (e.g. to replace an image that is currently unavailable or corrupted) would provide a clinician as well as downstream inference methods with important complementary information for disease analysis. In this paper, we present an end-to-end 3D convolution neural network that takes a set of acquired MR image sequences (e.g. T1, T2, T1ce) as input and concurrently performs (1) regression of the missing full resolution 3D MRI (e.g. FLAIR) and (2) segmentation of the tumour into subtypes (e.g. enhancement, core). The hypothesis is that this would focus the network to perform accurate synthesis in the area of the tumour. Experiments on the BraTS 2015 and 2017 datasets [1] show that: (1) the proposed method gives better performance than state-of-the-art methods in terms of established global evaluation metrics (e.g. PSNR), (2) replacing real MR volumes with the synthesized MRI does not lead to significant degradation in tumour and sub-structure segmentation accuracy. The system further provides uncertainty estimates based on Monte Carlo (MC) dropout [11] for the synthesized volume at each voxel, permitting quantification of the system's confidence in the output at each location.Comment: Accepted at Workshop on Simulation and Synthesis in Medical Imaging - SASHIMI2018 held in conjunction with the 21st International Conference on Medical Image Computing and Computer Assisted Intervention (MICCAI 2018