2,109 research outputs found
The Massive End of the Stellar Mass Function
We derive average flux corrections to the \texttt{Model} magnitudes of the
Sloan Digital Sky Survey (SDSS) galaxies by stacking together mosaics of
similar galaxies in bins of stellar mass and concentration. Extra flux is
detected in the outer low surface brightness part of the galaxies, leading to
corrections ranging from 0.05 to 0.32 mag for the highest stellar mass
galaxies. We apply these corrections to the MPA-JHU (Max-Planck Institute for
Astrophysics - John Hopkins University) stellar masses for a complete sample of
half a million galaxies from the SDSS survey to derive a corrected galaxy
stellar mass function at in the stellar mass range
. We find that the flux corrections and the use
of the MPA-JHU stellar masses have a significant impact on the massive end of
the stellar mass function, making the slope significantly shallower than that
estimated by Li \& White (2009), but steeper than derived by Bernardi et al.
(2013). This corresponds to a mean comoving stellar mass density of galaxies
with stellar masses that is a factor of 3.36
larger than the estimate by Li \& White (2009), but is 43\% smaller than
reported by Bernardi et al. (2013).Comment: 11 pages, 8 figures, Accepted to MNRA
Parametrizing the Stellar Haloes of Galaxies
We study the stellar haloes of galaxies out to 70-100 kpc as a function of
stellar mass and galaxy type by stacking aligned and band images from a
sample of 45508 galaxies from SDSS DR9 in the redshift range
and in the mass range r. We derive surface brightness profiles to a depth of
almost . We find that the
ellipticity of the stellar halo is a function of galaxy stellar mass and that
the haloes of high concentration () galaxies are more elliptical than
those of low concentration () galaxies. The - colour profile of
high concentration galaxies reveals that the - colour of the stellar
population in the stellar halo is bluer than in the main galaxy, and the colour
of the stellar halo is redder for higher mass galaxies. We further demonstrate
that the full two-dimensional surface intensity distribution of our galaxy
stacks can only be fit through multi-component S\'{e}rsic models. Using the
fraction of light in the outer component of the models as a proxy for the
fraction of accreted stellar light, we show that this fraction is a function of
stellar mass and galaxy type. For high concentration galaxies, the fraction of
accreted stellar light rises from to for galaxies in the stellar
mass range from to . The fraction of
accreted light is much smaller in low concentration systems, increasing from
to over the same mass range. This work provides important
constraints for the theoretical understanding of the formation of stellar
haloes of galaxies.Comment: Submitted to MNRAS, 18 pages, 19 figure
Two-Week versus Six-Month Sampling Interval in a Short-Term Natural History Study of Oral HPV Infection in an HIV-Positive Cohort
BACKGROUND: Oral HPV infections detected six-months apart were compared to those detected bi-weekly, in an HIV-positive cohort, during the intervening months to elucidate systematic biases introduced into natural history studies by sampling interval. METHODS: Fourteen consecutive oral rinse samples were collected every two weeks for six months from an HIV-positive cohort (n = 112) and evaluated for the presence of 37 HPV types. The cumulative probability of type-specific HPV detection at visits 1 through 14 was determined as a function of infection categorized at visits 1 and 14 as persistent, newly detected, cleared or absent. Transition models were used to evaluate the effect of HPV viral load (measured by RT-PCR for HPV 16, 18, 31, 33, 35) on infection persistence. RESULTS: The average point prevalence of oral HPV infection was similar at two-week and six-month sampling intervals (45% vs. 47%, p = 0.52), but cumulative prevalence was higher with the former (82% vs. 53%, p<0.001) as was the cumulative prevalence of type-specific infections (9.3% vs 3.8%, p<0.0001). Type-specific infections persistent under a six-month sampling interval had a high probability (0.93, 95%CI 0.83-0.98) of detection at 50% or more of the intervening visits and infections that were absent had a high probability (0.94, 95% CI 0.93-0.95) of no interval detection. The odds of detection at any visit significantly increased for each unit increase in HPV viral load at the previous visit. CONCLUSIONS: Six-month sampling is appropriate to model factors associated with type-specific oral HPV infection persistence but may misclassify HPV-exposed individuals as unexposed
Expression and regulation of Cek-8, a cell to cell signalling receptor in developing chick limb buds
Testing equivalence of pure quantum states and graph states under SLOCC
A set of necessary and sufficient conditions are derived for the equivalence
of an arbitrary pure state and a graph state on n qubits under stochastic local
operations and classical communication (SLOCC), using the stabilizer formalism.
Because all stabilizer states are equivalent to a graph state by local unitary
transformations, these conditions constitute a classical algorithm for the
determination of SLOCC-equivalence of pure states and stabilizer states. This
algorithm provides a distinct advantage over the direct solution of the
SLOCC-equivalence condition for an unknown invertible local operator S, as it
usually allows for easy detection of states that are not SLOCC-equivalent to
graph states.Comment: 9 pages, to appear in International Journal of Quantum Information;
Minor typos corrected, updated references
Rubrics in Nursing Education
Evaluating assignments or course work is a challenging job for faculty of
nursing. In order to avoid the dilemmas of evaluation, nurse educators use
rubrics as an evaluation tool. In educational technology, rubric refers to
„performance standard‟ for a student population. A rubric is defined as an
assessment tool that lays out the set standards and criteria to assess a
performance, assignment or behavior. The four essential components of a
rubric are task description, scale of achievement, dimensions & description
of dimensions. Various types of scoring rubrics are available. The type of
rubric chosen for assessment depends on the task being evaluated and the
needs of the assessor. Holistic rubrics, analytic rubrics, generic rubrics,
specific rubrics are the different types of rubrics. In nursing education,
rubrics has got wide range of applications such as to; assess clinical skills,
grade assignments, evaluate clinical competency and analyze presentations.
Rubrics helps to define "quality performance” and promote awareness on
critical components in a performance. Rubrics not only act as an evaluation
tool for instructors, but also act as a feedback proforma for students. Rubrics
are vital tools that can be utilized to solve the problem of subjectivity in
evaluation. Rubrics provide consistency in evaluation, reduces subjectivity
and enhances objectivity
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