198 research outputs found
WSRT observations and surface photometry of two unusual spiral galaxies
We discuss the results of a mass decomposition of two spiral galaxies, NGC
6824 and UGC 11919. In a previous analysis of the Hyperleda catalog, the
galaxies were identified as having a peculiar dynamical . The aim of this
study is to confirm or disprove the preliminary findings, indicating a
non-standard stellar initial mass function (IMF) for the galaxies. The surface
photometry in B, V, and R bands was carried out with the Apache Point 0.5-m
telescope and the \ion{H}{I} data cubes were obtained with the Westerbork
Synthesis Radio Telescope (WSRT). Photometric profiles were decomposed into
bulge and exponential disk components. Using the obtained \ion{H}{I} data
cubes, rotation curves of both galaxies were constructed. Employing the
photometric profiles, the mass distribution of the galaxies was decomposed into
mass components: bulge, stellar disk, gas, and pseudo-isothermal dark halo. We
conclude that NGC 6824 possesses a stellar disk with mass-to-light ratio
, in agreement with its color . On the
contrary, UGC 11919 appears to have a very lightweight disk. Its dynamically
estimated mass corresponds to a low stellar disk mass-to-light ratio
. Under standard assumptions, this ratio does
not agree with the relatively red color of the disk, while a bottom light
stellar initial mass function is needed to explain the observations.Comment: 14 pages, 14 figures, accepted for publication in Astronomy and
Astrophysic
Towards a Full Census of the Obscure(d) Vela Supercluster using MeerKAT
Recent spectroscopic observations of a few thousand partially obscured
galaxies in the Vela constellation revealed a massive overdensity on
supercluster scales straddling the Galactic Equator (l 272.5deg) at km/s. It remained unrecognised because it is located just beyond the
boundaries and volumes of systematic whole-sky redshift and peculiar velocity
surveys - and is obscured by the Milky Way. The structure lies close to the
apex where residual bulkflows suggest considerable mass excess. The uncovered
Vela Supercluster (VSCL) conforms of a confluence of merging walls, but its
core remains uncharted. At the thickest foreground dust column densities (|b| <
6 deg) galaxies are not visible and optical spectroscopy is not effective. This
precludes a reliable estimate of the mass of VSCL, hence its effect on the
cosmic flow field and the peculiar velocity of the Local Group. Only systematic
HI-surveys can bridge that gap. We have run simulations and will present
early-science observing scenarios with MeerKAT 32 (M32) to complete the census
of this dynamically and cosmologically relevant supercluster. M32 has been put
forward because this pilot project will also serve as precursor project for HI
MeerKAT Large Survey Projects, like Fornax and Laduma. Our calculations have
shown that a survey area of the fully obscured part of the supercluster, where
the two walls cross and the potential core of the supercluster resides, can be
achieved on reasonable time-scales (200 hrs) with M32.Comment: 10 pages, 3 figures, accepted for publication, Proceedings of
Science, workshop on "MeerKAT Science: On the Pathway to the SKA", held in
Stellenbosch 25-27 May 201
USE OF GROWTH ANALYSIS TO EVALUATE GENETIC MECHANISMS AFFECTING ACHENE YIELD FORMATION OF SUNFLOWER
The main objective of this study was to investigate the process of dry matter accumulation (DMA) in achenes during the grain-filling period of fifty sunflower genotypes by using the functional method of growth analysis in a field trial at Bicsérd, Hungary. The Hunt-formula of lnY= P0 + P1*X + P2*X2 was fitted to data. Maximum yield (Ymax), the average of the absolute growth rate (AGRavg), maximum growth rate (AGRmax), date of the maximum growth rate (Xagrmax), and the average of the relative growth rate (RGRavg) were calculated from growth curves for hybrids and replications. Significant differences among hybrids and their interaction with sampling dates indicate hybrid differences in the intensity of DMA
accumulation. The strongest correlation was observed between the parameters of Ymax and AGRmax
Shocked Minerals in NWA 5011 L6 Chondritic Meteorite.
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月18日(金) 国立国語研究所 2階講
Opportunities and challenges in partitioning the graph measure space of real-world networks
Based on a large dataset containing thousands of real-world networks ranging from genetic, protein interaction, and metabolic networks to brain, language, ecology, and social networks we search for defining structural measures of the different complex network domains (CND). We calculate 208 measures for all networks and using a comprehensive and scrupulous workflow of statistical and machine learning methods we investigated the limitations and possibilities of identifying the key graph measures of CNDs. Our approach managed to identify well distinguishable groups of network domains and confer their relevant features. These features turn out to be CND specific and not unique even at the level of individual CNDs. The presented methodology may be applied to other similar scenarios involving highly unbalanced and skewed datasets
Mastery motivation of university students in Australia, Hungary, Bangladesh and Iran
This study trialed a newly developed measure of adult mastery motivation in four different cultural contexts. The Dimensions of Adult Mastery Motivation Questionnaire was translated into Hungarian and Persian languages. A total of 469 university students in Australia, Hungary, Bangladesh and Iran completed the questionnaire about their levels of persistence, preference for challenge, task absorption, and task pleasure. Cronbach alphas for the total mastery motivation scale and most subscales were acceptable to good. There were no differences in self-reported mastery motivation across the four countries, but significant gender differences were evident. In all countries except Hungary, male students reported higher levels of mastery motivation. The DAMMQ appears to be a useful measure of mastery motivation across diverse cultures. The findings provide some support for the universality of the theoretical construct of mastery motivation and suggest the potential need for universities to encourage and nurture female students in their striving for mastery. Given the importance of university education for a country’s prosperity, understanding the motivational factors that underlie academic success is imperative to inform policies and programs for increasing student retention and individual well-being
Identification of Pyroxene-Akimotoite Phase Transformation in NWA 5011 L6 Chondrite: Confirmation of the Preliminary Optical Observations
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月17日(木) 国立国語研究所 2階講
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