1,103 research outputs found
The Baryon Content of Extremely Low Mass Dwarf Galaxies
We investigate the gas content and baryonic Tully-Fisher relationship for
extremely low luminosity dwarf galaxies in the absolute magnitude range -13.5 >
Mr > -16. The sample is selected from the Sloan Digital Sky Survey and consists
of 101 galaxies for which we have obtained follow-up HI observations using the
Arecibo Observatory and Green Bank Telescope. This represents the largest
homogeneous sample of dwarfs at low luminosities with well-measured HI and
optical properties. The sample spans a range of environments, from dense groups
to truly isolated galaxies. The average neutral gas fraction is f_gas=0.6,
significantly exceeding that of typical gas-rich galaxies at higher
luminosities. Dwarf galaxies are therefore less efficient at turning gas into
stars over their lifetimes. The strong environmental dependence of the gas
fraction distribution demonstrates that while internal processes can reduce the
gas fractions to roughly f_gas=0.4, external processes are required to fully
remove gas from a dwarf galaxy. The average rotational velocity of our sample
is vrot=50 km/s. Including more massive galaxies from the literature, we fit a
baryonic Tully-Fisher slope of M_baryon \propto vrot^(3.70+/- 0.15). This slope
compares well with CDM models that assume an equal baryon to dark matter ratio
at all masses. While gas stripping or other processes may modify the baryon to
dark matter ratio for dwarfs in the densest environments, the majority of dwarf
galaxies in our sample have not preferentially lost significant baryonic mass
relative to more massive galaxies.Comment: 33 pages, 8 figures. Accepted to ApJ. Data available at
http://www.ociw.edu/~mgeha/researc
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Attitudinal Determinants of diet and lifestyle among African and Caribbean women living in the UK : study design and rationale
The aim of this article is to describe the rationale and design of a cross-sectional study that investigated the influence of attitudinal factors on diet and lifestyle of African and Caribbean women living in the UK. The results of the study will be presented elsewhere. African and Caribbean women are at high risk of obesity which exacerbates health inequalities. In the UK, little work has been carried out to better understand attitudinal factors that contribute towards obesity, lifestyle and health practice amongst this group.
Methods:
The study applied a comprehensive questionnaire to capture socio-demographic data and explore general attitudes towards diet and lifestyle of African and Caribbean women. Dietary data were collected using triple-pass 24-hour recalls. In addition, all participants had anthropometric measures, blood pressure and biochemical indices assessed using standardised methods.
Discussion:
Potential strengths and limitations of the current study design, exploring health, diet, and lifestyle habits and the contextual influence on these practices among African and Caribbean in the UK are discussed. Findings from this study will contribute to the understanding of food and health practices, the role of socio-cultural factors and potential barriers and facilitators to the adoption of a healthy lifestyle, which could reduce the risk of cardiovascular disease, obesity, and type 2 diabetes, all of which have increased prevalence in these communities
FIGGS: Faint Irregular Galaxies GMRT Survey - Overview, observations and first results
The Faint Irregular Galaxies GMRT Survey (FIGGS) is a Giant Metrewave Radio
Telescope (GMRT) based HI imaging survey of a systematically selected sample of
extremely faint nearby dwarf irregular galaxies. The primary goal of FIGGS is
to provide a comprehensive and statistically robust characterization of the
neutral inter-stellar medium properties of faint, gas rich dwarf galaxies. The
FIGGS galaxies represent the extremely low-mass end of the dwarf irregular
galaxies population, with a median M and median HI mass of
M, extending the baseline in mass and luminosity
space for a comparative study of galaxy properties. The HI data is supplemented
with observations at other wavelengths. In addition, distances accurate to ~
10% are available for most of the sample galaxies. This paper gives an
introduction to FIGGS, describe the GMRT observations and presents the first
results from the HI observations. From the FIGGS data we confirm the trend of
increasing HI to optical diameter ratio with decreasing optical luminosity; the
median ratio of D/D for the FIGGS sample is 2.4. Further,
on comparing our data with aperture synthesis surveys of bright spirals, we
find at best marginal evidence for a decrease in average surface density with
decreasing HI mass. To a good approximation the disks of gas rich galaxies,
ranging over 3 orders of magnitude in HI mass, can be described as being drawn
from a family with constant HI surface density.Comment: 17 pages, 14 figures. Accepted for publication in MNRA
Structure of the SMC - Stellar component distribution from 2MASS data
The spatial distribution of the SMC stellar component is investigated from
2MASS data. The morphology of the different age populations is presented. The
center of the distribution is calculated and compared with previous
estimations. The rotation of the stellar content and possible consequence of
dark matter presence are discussed. The different stellar populations are
identified through a CMD diagram of the 2MASS data. Isopleth contour maps are
produced in every case, to reveal the spatial distribution. The derived density
profiles are discussed. The older stellar population follows an exponential
profile at projected diameters of about 5 kpc (~5 deg) for the major axis and
~4 kpc for the minor axis, centred at RA: 0h:51min, Dec: -73deg 7' (J2000.0).
The centre coordinates are found the same for all the different age population
maps and are in good accordance with the kinematical centre of the SMC. However
they are found considerably different from the coordinates of the centre of the
gas distribution. The fact that the older population found on an exponential
disk, gives evidence that the stellar content is rotating, with a possible
consequence of dark matter presence. The strong interactions between the MCs
and the MilkyWay might explain the difference in the distributions of the
stellar and gas components. The lack in the observed velocity element, that
implies absence of rotation, and contradicts with the consequences of
exponential profile of the stellar component, may also be a result of the
gravitational interactions.Comment: 7 Pages, 6 figures, accepted for publication in A&
Study of genetic variation of some eggplant cultivars through RAPD-PCR molecular markers and its relatedness to phomopsis blight disease reaction
Disease susceptibility and genetic variability in 10 eggplant genotypes were studied after inoculating Phomopsis vexans under confined field conditions. Random amplified polymorphic DNA (RAPD) markers were used to assess genetic variation and relationships among eggplant genotypes. The disease index of leaves ranged 0.208-13.79%, while fruit infection ranged 2.15-42.76%. Two varieties, Dohazari G and Laffa S, were found to be susceptible, 6 were moderately resistant, 1 was moderately susceptible, and BAU Begun-1 was resistant to P. vexans. Amplification of genomic DNA by using 3 RAPD primers produced 20 bands: 14 (70%) were polymorphic and 6 (30%) were monomorphic. The highest intra-variety similarity indices values were found in ISD 006, Ishurdi L, Jessore L, and BAU Begun-1 (100%), while the lowest was in Dohazari G (90%). The lowest genetic distance (0.0513) and the highest genetic identity (0.9500) were observed between the ISD 006 and Ishurdi L combinations. A comparatively higher genetic distance (0.3724) and the lowest genetic identity (0.6891) were observed between the ISD 006 and Dohazari G combinations. A dendogram was constructed based on Nei’s genetic distance, which produced 2 main clusters of the genotypes - Cluster I: ISD 006, Ishurdi L, Marich begun L, BAU Begun-1, Marich begun S, and Chega and Cluster 2: Laffa S, Dohazari G, Jessore L, and Singhnath. Genetic variation and its relationship with disease susceptibility were assessed using RAPD markers, to develop disease-resistant varieties and improve eggplant crops
Thrombocytosis in relation to severity of lower respiratory tract infection in children aged 2 months to 5 years
Background: Primary or essential thrombocytosis in children is very rare but reactive thrombocytosis occurs in children and respiratory tract infection is the commonest cause. The study aimed to determine the association of thrombocytosis with severity of lower respiratory tract infection; and the association of degree of thrombocytosis with severity of pneumonia. Materials and methods: This observational study was conducted in the Department of Paediatrics of Fakhruddin Ali Ahmed Medical College & Hospital, Barpeta in Assam. This study was done on 120 children aged between 2 months and 5 years who were admitted with lower respiratory tract infection and classified according to WHO guidelines. Complete general physical examination and systemic examination with special orientation towards respiratory system was done. Complete blood count was performed with automated system sysmex xs800i cell counter. Thrombocytosis was noted and severity of thrombocytosis was classified.
Results: Among 120 cases of lower respiratory tract infections, 48 children had thrombocytosis. 13 (48.1%) children with very severe disease, 29 (46.1%) children with severe pneumonia and 6(20%) children with pneumonia had thrombocytosis. Thus it was seen that there was significant association between platelet count and severity of pneumonia (p value=0.018). Two children had severe thrombocytosis (9.01-10.00L/mm3) and both of them had very severe disease. It indicates that degree of thrombocytosis increases as severity of pneumonia increases.
Conclusion: There is a significant relationship between thrombocytosis and severity of pneumonia. Also degree of thrombocytosis increases as severity of pneumonia increases
Binary Galaxies in the Local Supercluster and Its Neighborhood
We report a catalog of 509 pairs identified among 10403 nearby galaxies with
line-of-sight velocities V_LG < 3500 km/s.We selected binary systems in
accordance with two criteria (bounding and temporal), which require the
physical pair of galaxies to have negative total energy and its components to
be located inside the zero-velocity surface. We assume that individual galaxy
masses are proportional to their total K-band luminosities, M = L_K x 6M/L. The
catalog gives the magnitudes and morphological types of galaxies and also the
projected (orbital) masses and pair isolation indices. The component
line-of-sight velocity differences and projected distances of the binary
systems considered have power-law distributions with the median values of 35
km/s and 123 kpc, respectively. The median mass-to-K-band luminosity ratio is
equal to 11 M/L, and its uncertainty is mostly due to the errors of measured
velocities. Our sample of binary systems has a typical density contrast of d
ro/ro_c ~ 500 and a median crossing time of about 3.5 Gyr. We point out the
substantial fraction of binary systems consisting of late-type dwarf galaxies,
where the luminosities of both components are lower than that of the Small
Magellanic Cloud. The median projected distance for 41 such pairs is only 30
kpc, and the median difference of their line-of-sight velocities is equal to 14
km/s which is smaller than the typical error for radial-velocity (30 km/s).
This specific population of gas-rich dwarf binary galaxies such as I Zw 18 may
be at the stage immediately before merging of its components. Such objects,
which are usually lost in flux-limited (and not distance-limited) samples
deserve a thorough study in the HI radio line with high spatial and velocity
resolution.Comment: published in Astrophysical Bulletin, 2008, Vol. 63, No. 4, pp.
299-34
Synthesis, characterisation and biological activities of S-2- or S-4-methylbenzyl-β-N-(di-2-pyridyl)methylenedithiocarbazate and Cu(II), Ni(II), Zn(II) and Cd(II) complexes
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