138 research outputs found
Literary and cinematic perspectives on gender studies
This project focuses on gender studies including women, men, and sexual diversity studies. Students explore gender and sexuality in the fields of literature and cinema related to cultural, social, and economic issues in Latin America and Spain. The analysis includes a diverse selection of topics: gender and science, gender and sexuality, gender and minority ethnicities, feminism and diversity, transgender identities, transgender healthcare, lesbian and gay figures and trends, and intersex and culture
SDSS IV MaNGA: Dependence of Global and Spatially Resolved SFR-M ∗ Relations on Galaxy Properties
Indexación: Scopus.The galaxy integrated Hα star formation rate-stellar mass relation, or SFR(global)-M ∗(global) relation, is crucial for understanding star formation history and evolution of galaxies. However, many studies have dealt with SFR using unresolved measurements, which makes it difficult to separate out the contamination from other ionizing sources, such as active galactic nuclei and evolved stars. Using the integral field spectroscopic observations from SDSS-IV MaNGA, we spatially disentangle the contribution from different Hα powering sources for ∼1000 galaxies. We find that, when including regions dominated by all ionizing sources in galaxies, the spatially resolved relation between Hα surface density (ΣHα(all)) and stellar mass surface density (Σ∗(all)) progressively turns over at the high Σ∗(all) end for increasing M ∗(global) and/or bulge dominance (bulge-to-total light ratio, B/T). This in turn leads to the flattening of the integrated Hα(global)-M ∗(global) relation in the literature. By contrast, there is no noticeable flattening in both integrated Hα(H ii)-M ∗(H ii) and spatially resolved ΣHα(H ii)-Σ∗(H ii) relations when only regions where star formation dominates the ionization are considered. In other words, the flattening can be attributed to the increasing regions powered by non-star-formation sources, which generally have lower ionizing ability than star formation. An analysis of the fractional contribution of non-star-formation sources to total Hα luminosity of a galaxy suggests a decreasing role of star formation as an ionizing source toward high-mass, high-B/T galaxies and bulge regions. This result indicates that the appearance of the galaxy integrated SFR-M ∗ relation critically depends on their global properties (M ∗(global) and B/T) and relative abundances of various ionizing sources within the galaxies.http://iopscience.iop.org/article/10.3847/1538-4357/aaa9bc/met
ISOLATION OF SOME WOOD DECAYING FUNGI AND STREPTOMYCES AND THEIR EFFECTS ON SOME COMMERCIAL TIMBER SPECIES IN SRI LANKA
Wood is subject to .utack by wood inhahiting fungi in a variety of environmental situationslrnm the standing tree to the wood product in service. An investigation was carried out tostudy the resistance or five conuncrcial timhcr species namely Rubber (111'1'('11 brasiliensis),Luuumidcll.r (Mcli« rlllhlll) Pine (PiIlIlS raribca). Mahogony (.)11'/1'11'11/0 I)I{/(.,.o/,llylla)andTeak (1""("/(11111 ,~nlllrlls) to lung.il attack.Four wood decaying fungal species were isolated from naturally infected wood samples,Three species namely Trirodcrma Sfl., Mycrlia stcrilia and Streptomvccs sfI. belonging toDcutcromycot ina subdivision and AspergillI'S sp. belonging to Ascomycotiua subdivisionwere identified. These species were used to assess the initial decay of wood. Out of thelour SI1l'l'ics tested SIU'f)/OIlIH'C.I .III. was the most destructive fungal species.The wl'i)!ht loss or timber was taken as parameter or decay. Wood species and the fungalxpccicx had a significant effect on the weight loss. The highest weight loss due to fungalattack was caused hy Strcptomvrcs species in all the timber species except in Lunumidcllawhere Trirodcrnia Sf' recorded the highest weight loss.In Rubber, Lunumidclla and Pinus moisture gain was observed with fungal attack whilemoisture loss was observed in controls. In Mahogany and Teak moisture gain due toIUllgal auack was negligihle. Since these fungi caused a considerable damage at the initialstage or decay they can he grouped as primary decaying fungi in wood.
FUNGAL SUCCESSION AND BIODEGRADTION OF RUBBER SAW DUST
Sri Lanka has a long tradition of saw milling, But the waste product (saw dust) from thesemills is not adequately utili sed for beneficial purposes. In a functioning sawmill about twohundred kilograms of organic matter is dispelled as saw dust everyday. Saw dust samples were kept in the garden exposed to normal climatic conditions, a greenhouse or on a laboratory bench for this study. Fungal species that appeared on sawdustwere isolated, identified and number of fungal colonies were counted by dilution platecount technique. During this study seven prominent fungal genera were observed. Fourspecies (Fusarium sp, Penicillium sp, Stemphy/ium sp, Trichodema sp) out of seven wereDeuteromycetes and these were observed in all the three conditions; Two species (Lentinussp and Coprines sp) were Basidiomycetes; one (Aspergillus sp) was Ascomycetes, Thefungal succession appeared in the saw dust showed that first fungal colonizers cause brownrot decay followed by white rot. Saw dust exposed to the fungal growth in laboratoryconditions showed the highest weight loss (42,86%) at the end of the study periodcompared with the weight loss observed in green house conditions and in laboratoryconditions,It is clear that these fungal species have the ability to degrade complex cellulose and ligninmolecules to simple compounds. Due to the fungal activity, weight and strength of the sawdust were reduced, and the texture changed. This showed that there is a possibility ofusing saw dust as a growing medium, after its deterioration by suitable fungi,
A recent rebuilding of most spirals ?
Re-examination of the properties of distant galaxies leads to the evidence
that most present-day spirals have built up half of their stellar masses during
the last 8 Gyr, mostly during several intense phases of star formation during
which they took the appearance of luminous infrared galaxies (LIRGs). Distant
galaxy morphologies encompass all of the expected stages of galaxy merging,
central core formation and disk growth, while their cores are much bluer than
those of present-day bulges. We have tested a spiral rebuilding scenario, for
which 75+/-25% of spirals have experienced their last major merger event less
than 8 Gyr ago. It accounts for the simultaneous decreases, during that period,
of the cosmic star formation density, of the merger rate, of the number
densities of LIRGs and of compact galaxies, while the densities of ellipticals
and large spirals are essentially unaffected.Comment: (1) GEPI, Obs. Meudon, France ;(2)Max-Planck Institut fuer
Astronomie, Germany (3) National Astronomical Observatories, CAS, China. Five
pages, 1 figure. To be published in "Starbursts: From 30 Doradus to Lyman
Break Galaxies", held in Cambridge, ed. R. de Grijs & R. M. Gonzalez Delgado
(Dordrecht: Kluwer
The cosmological origin of the Tully-Fisher relation
We use high-resolution cosmological simulations that include the effects of
gasdynamics and star formation to investigate the origin of the Tully-Fisher
relation in the standard Cold Dark Matter cosmogony. Luminosities are computed
for each model galaxy using their full star formation histories and the latest
spectrophotometric models. We find that at z=0 the stellar mass of model
galaxies is proportional to the total baryonic mass within the virial radius of
their surrounding halos. Circular velocity then correlates tightly with the
total luminosity of the galaxy, reflecting the equivalence between mass and
circular velocity of systems identified in a cosmological context. The slope of
the relation steepens slightly from the red to the blue bandpasses, and is in
fairly good agreement with observations. Its scatter is small, decreasing from
\~0.45 mag in the U-band to ~0.34 mag in the K-band. The particular
cosmological model we explore here seems unable to account for the zero-point
of the correlation. Model galaxies are too faint at z=0 (by about two
magnitudes) if the circular velocity at the edge of the luminous galaxy is used
as an estimator of the rotation speed. The Tully-Fisher relation is brighter in
the past, by about ~0.7 magnitudes in the B-band at z=1, at odds with recent
observations of z~1 galaxies. We conclude that the slope and tightness of the
Tully-Fisher relation can be naturally explained in hierarchical models but
that its normalization and evolution depend strongly on the star formation
algorithm chosen and on the cosmological parameters that determine the
universal baryon fraction and the time of assembly of galaxies of different
mass.Comment: 5 pages, 4 figures included, submitted to ApJ (Letters
International health and Hispanic culture
This research project focuses on the interrelations between health and culture in the Hispanic countries and their impact on individuals and communities. The research explores medical diseases and conditions, people\u27s traditions, beliefs, and perceptions related to concerns related to health issues, home remedies, behavior change, family and community, doctor-patient relationship, and social aspects of public health (ethnicity, gender, poverty). Students will have the opportunity to travel to the Dominican Republic with the researchers and participate in service learning activities to help Hispanic communities and collect data for this research project. CI students will lead the following research topics in the Dominican Republic: 1) self-medication, low-income population accessibility to medicines, and the governmental pharmacy system (Boticas Populares) (Caleb Addis); 2) domestic violence as a public health concern (Aliyah Anjarwalla); 3) how chronic diseases are promoted, prevented and controlled (Deepti Athavale); 4) hepatitis A as a public health concern (Thomas Cotton); 5) challenges/barriers of people with disabilities to access physical therapy services (Breci Davis) ; 6) cultural and socio-economic determinants of childhood obesity (Michelle Fuentes); 7)medical equipment maintenance at public health care settings: advantages and disadvantages of donated equipment (Hannah Haire); 8) challenges and opportunities for the implementation of the HIV Vertical Transmission Prevention Program (Ashley Jamison); and 9) a behavioral theory analysis of drug abuse (Katherine Orellana)
Conservation Laws in Smooth Particle Hydrodynamics: the DEVA Code
We describe DEVA, a multistep AP3M-like-SPH code particularly designed to
study galaxy formation and evolution in connection with the global cosmological
model. This code uses a formulation of SPH equations which ensures both energy
and entropy conservation by including the so-called \bn h terms. Particular
attention has also been paid to angular momentum conservation and to the
accuracy of our code. We find that, in order to avoid unphysical solutions, our
code requires that cooling processes must be implemented in a non-multistep
way.
We detail various cosmological simulations which have been performed to test
our code and also to study the influence of the \bn h terms. Our results
indicate that such correction terms have a non-negligible effect on some
cosmological simulations, especially on high density regions associated either
to shock fronts or central cores of collapsed objects. Moreover, they suggest
that codes paying a particular attention to the implementation of conservation
laws of physics at the scales of interest, can attain good accuracy levels in
conservation laws with limited computational resources.Comment: 36 pages, 10 figures. Accepted for publication in The Astrophysical
Journa
Halo orbits in cosmological disk galaxies : tracers of information history
We analyze the orbits of stars and dark matter particles in the halo of a disk galaxy formed in a cosmological hydrodynamical simulation. The halo is oblate within the inner ∼20 kpc and triaxial beyond this radius. About 43% of orbits are short axis tubes—the rest belong to orbit families that characterize triaxial potentials (boxes, long-axis tubes and chaotic orbits), but their shapes are close to axisymmetric. We find no evidence that the self-consistent distribution function of the nearly oblate inner halo is comprised primarily of axisymmetric short-axis tube orbits. Orbits of all families and both types of particles are highly eccentric, with mean eccentricity �0.6. We find that randomly selected samples of halo stars show no substructure in “integrals of motion” space. However, individual accretion events can clearly be identified in plots of metallicity versus formation time. Dynamically young tidal debris is found primarily on a single type of orbit. However, stars associated with older satellites become chaotically mixed during the formation process (possibly due to scattering by the central bulge and disk, and baryonic processes), and appear on all four types of orbits. We find that the tidal debris in cosmological hydrodynamical simulations experiences significantly more chaotic evolution than in collisionless simulations, making it much harder to identify individual progenitors using phase space coordinates alone. However, by combining information on stellar ages and chemical abundances with the orbital properties of halo stars in the underlying self-consistent potential, the identification of progenitors is likely to be possible
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