167 research outputs found
Verão em Portugal (Text)
Get PDFThis text and translation into English accompanies an illustrated podcast in European Portuguese was created by Will Masters, a student of Applied Languages at the School of Languages and Area Studies, University of Portsmouth, as a part of a research project entitled ‘The Role of Student Audio Casting and Production in the Language Learning Curriculum’. The recording presents a refelction on the student's first experiences of Portugal, and of learning Portuguese. The podcast can be used as a learning resource in several different ways: as a focus for discussion or aural comprehension by students of the Portuguese language
The progenitors of present-day massive red galaxies up to z∼0.7 - finding passive galaxies using SDSS-I/II and SDSS-III
Get PDF
Evolution of the Clustering of Photometrically Selected SDSS Galaxies
Get PDFWe measure the angular auto-correlation functions (w) of SDSS galaxies
selected to have photometric redshifts 0.1 < z < 0.4 and absolute r-band
magnitudes Mr < -21.2. We split these galaxies into five overlapping redshift
shells of width 0.1 and measure w in each subsample in order to investigate the
evolution of SDSS galaxies. We find that the bias increases substantially with
redshift - much more so than one would expect for a passively evolving sample.
We use halo-model analysis to determine the best-fit
halo-occupation-distribution (HOD) for each subsample, and the best-fit models
allow us to interpret the change in bias physically. In order to properly
interpret our best-fit HODs, we convert each halo mass to its z = 0 passively
evolved bias (bo), enabling a direct comparison of the best-fit HODs at
different redshifts. We find that the minimum halo bo required to host a galaxy
decreases as the redshift decreases, suggesting that galaxies with Mr < -21.2
are forming in halos at the low-mass end of the HODs over our redshift range.
We use the best-fit HODs to determine the change in occupation number divided
by the change in mass of halos with constant bo and we find a sharp peak at bo
~ 0.9 - corresponding to an average halo mass of ~ 10^12Msol/h. We thus present
the following scenario: the bias of galaxies with Mr < -21.2 decreases as the
Universe evolves because these galaxies form in halos of mass ~ 10^12Msol/h
(independent of redshift), and the bias of these halos naturally decreases as
the Universe evolves.Comment: 17 pages, 14 figures, matches version accepted for publication in
MNRA
Rapidly Progressive Dementia Due to Mycobacterium neoaurum Meningoencephalitis
Get PDFDementia developed in a patient with widespread neurologic manifestations; she died within 5 months. Pathologic findings showed granulomatous inflammation with caseation necrosis, foreign body–type giant cells, and proliferative endarteritis with vascular occlusions. Broad-range polymerase chain reaction identified Mycobacterium neoaurum as the possible pathogen. Central nervous system infection by M. neoaurum may result in rapidly progressive dementia
Ameliorating Systematic Uncertainties in the Angular Clustering of Galaxies: A Study using SDSS-III
Get PDFWe investigate the effects of potential sources of systematic error on the
angular and photometric redshift, z_phot, distributions of a sample of redshift
0.4 < z < 0.7 massive galaxies whose selection matches that of the Baryon
Oscillation Spectroscopic Survey (BOSS) constant mass sample. Utilizing over
112,778 BOSS spectra as a training sample, we produce a photometric redshift
catalog for the galaxies in the SDSS DR8 imaging area that, after masking,
covers nearly one quarter of the sky (9,913 square degrees). We investigate
fluctuations in the number density of objects in this sample as a function of
Galactic extinction, seeing, stellar density, sky background, airmass,
photometric offset, and North/South Galactic hemisphere. We find that the
presence of stars of comparable magnitudes to our galaxies (which are not
traditionally masked) effectively remove area. Failing to correct for such
stars can produce systematic errors on the measured angular auto-correlation
function, w, that are larger than its statistical uncertainty. We describe how
one can effectively mask for the presence of the stars, without removing any
galaxies from the sample, and minimize the systematic error. Additionally, we
apply two separate methods that can be used to correct the systematic errors
imparted by any parameter that can be turned into a map on the sky. We find
that failing to properly account for varying sky background introduces a
systematic error on w. We measure w, in four z_phot slices of width 0.05
between 0.45 < z_phot < 0.65 and find that the measurements, after correcting
for the systematic effects of stars and sky background, are generally
consistent with a generic LambdaCDM model, at scales up to 60 degrees. At
scales greater than 3 degrees and z_phot > 0.5, the magnitude of the
corrections we apply are greater than the statistical uncertainty in w.Comment: Accepted by MNRA
SDSS-III Baryon Oscillation Spectroscopic Survey data release 12 : galaxy target selection and large-scale structure catalogues
Get PDFThe Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey (SDSS) III project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. Key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. Potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets for which redshifts were not obtained, and variations in the target sky density due to observational systematics. We document here the target selection algorithms used to create the galaxy samples that comprise BOSS. We also present the algorithms used to create large-scale structure catalogues for the final Data Release (DR12) samples and the associated random catalogues that quantify the survey mask. The algorithms are an evolution of those used by the BOSS team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. The code used, designated mksample, is released with this paper.Publisher PDFPeer reviewe
Binding of the 5′-untranslated region of coronavirus RNA to zinc finger CCHC-type and RNA-binding motif 1 enhances viral replication and transcription
Get PDFCoronaviruses RNA synthesis occurs in the cytoplasm and is regulated by host cell proteins. In a screen based on a yeast three-hybrid system using the 5′-untranslated region (5′-UTR) of SARS coronavirus (SARS-CoV) RNA as bait against a human cDNA library derived from HeLa cells, we found a positive candidate cellular protein, zinc finger CCHC-type and RNA-binding motif 1 (MADP1), to be able to interact with this region of the SARS-CoV genome. This interaction was subsequently confirmed in coronavirus infectious bronchitis virus (IBV). The specificity of the interaction between MADP1 and the 5′-UTR of IBV was investigated and confirmed by using an RNA pull-down assay. The RNA-binding domain was mapped to the N-terminal region of MADP1 and the protein binding sequence to stem–loop I of IBV 5′-UTR. MADP1 was found to be translocated to the cytoplasm and partially co-localized with the viral replicase/transcriptase complexes (RTCs) in IBV-infected cells, deviating from its usual nuclear localization in a normal cell using indirect immunofluorescence. Using small interfering RNA (siRNA) against MADP1, defective viral RNA synthesis was observed in the knockdown cells, therefore indicating the importance of the protein in coronaviral RNA synthesis
The different star formation histories of blue and red spiral and elliptical galaxies
Get PDFWe study the spectral properties of intermediate mass galaxies (M* ∼ 1010.7 M⊙) as a function of colour and morphology. We use Galaxy Zoo to define three morphological classes of galaxies, namely early types (ellipticals), late-type (disc-dominated) face-on spirals and early-type (bulge-dominated) face-on spirals. We classify these galaxies as blue or red according to their Sloan Digital Sky Survey (SDSS) g − r colour and use the spectral fitting code Versatile Spectral Analyses to calculate time-resolved star formation histories, metallicity and total starlight dust extinction from their SDSS fibre spectra. We find that red late-type spirals show less star formation in the last 500 Myr than blue late-type spirals by up to a factor of 3, but share similar star formation histories at earlier times. This decline in recent star formation explains their redder colour: their chemical and dust content are the same. We postulate that red late-type spirals are recent descendants of blue late-type spirals, with their star formation curtailed in the last 500 Myr. The red late-type spirals are however still forming stars ≃17 times faster than red ellipticals over the same period. Red early-type spirals lie between red late-type spirals and red ellipticals in terms of recent-to-intermediate star formation and dust content. Therefore, it is plausible that these galaxies represent an evolutionary link between these two populations. They are more likely to evolve directly into red ellipticals than red late-type spirals, which show star formation histories and dust content closer to blue late-type spirals. Blue ellipticals show similar star formation histories as blue spirals (regardless of type), except that they have formed less stars in the last 100 Myr. However, blue ellipticals have different dust content, which peaks at lower extinction values than all spiral galaxies. Therefore, many blue ellipticals are unlikely to be descendants of blue spirals, suggesting there may not be single evolutionary path for this group of galaxies.Publisher PDFPeer reviewe
- …
