391 research outputs found
A study of the reactions of third grade pupils to the various types of children's literature that were available during three specific periods: 1900-1920; 1920-1940; 1940-1953
Thesis (Ed.M.)--Boston Universit
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Student storytelling: A strategy for developing oral literacy in the intermediate grades
What is the most effective way to treat recurrent canker sores?
Amlexanox appears to be most effective overall. Amlexanox 5% paste reduces ulcer size, pain duration, and healing time (strength of recommendation [SOR]: A, multiple randomized controlled trials [RCTs]). Topical steroids may alleviate pain and decrease ulcer burden, defined as total number of ulcers over a measured time, usually 4 to 6 weeks (SOR: B, multiple small heterogenous RCTs). Chemical cautery agents also lessen pain (SOR: A, single RCTs on differing agents), and chlorhexidine mouthwashes may reduce overall ulcer burden (SOR: B, heterogeneous RCTs). The herbal preparation Eupatorium laevigatum alleviates pain and improves healing (SOR: B, single RCT). Oral vitamin B12 supplements and avoiding toothpastes containing sodium lauryl sulfate may prevent recurrent ulcers (SOR: B, small RCTs)
Extragalactic Constraints on the Initial Mass Function
The local stellar mass density is observed to be significantly lower than the
value obtained from integrating the cosmic star formation history (SFH),
assuming that all the stars formed with a Salpeter initial mass function (IMF).
Even other favoured IMFs, more successful in reconciling the observed
stellar mass density with that inferred from the SFH, have difficulties in
reproducing the stellar mass density observed at higher redshift. In this study
we investigate to what extent this discrepancy can be alleviated for any
universal power-law IMF. We find that an IMF with a high-mass slope shallower
(2.15) than the Salpeter slope (2.35) reconciles the observed stellar mass
density with the cosmic star formation history, but only at low redshifts. At
higher redshifts we find that observed stellar mass densities are
systematically lower than predicted from the cosmic star formation history, for
any universal power-law IMF.Comment: 6 pages, 5 figures, accepted to MNRA
Immunoglobulin G from bovine milk primes intestinal epithelial cells for increased colonization of bifidobacteria
peer-reviewedAbstract
A bovine colostrum fraction (BCF) was recently shown to enhance the adherence of several commensal organisms to intestinal epithelial cells through modulating the epithelial cell surface. In this study, the main components of the BCF were examined to investigate the active component/s responsible for driving the changes in the intestinal cells. The adherence of various bifidobacteria to HT-29 cells was increased when the intestinal cells were pre-incubated with immunoglobulin G (IgG). Modulation of the intestinal cells by IgG was concentration dependent with 16 mg/mL IgG resulting in a 43-fold increase in the adhesion of Bifidobacterium longum NCIMB 8809 to HT-29 cells. Periodate treatment of colostral IgG prior to performing the colonization studies resulted in a reduction in the adhesion of the strain to the intestinal cells demonstrating that the glycans of IgG may be important in modulating the intestinal cells for enhanced commensal adhesion. IgG isolated from mature milk also resulted in significant increases in adhesion of the Bifidobacterium strains tested albeit at reduced levels (3.9-fold). The impact of IgG on the HT-29 cells was also visualised via scanning electron microscopy. This study builds a strong case for the inclusion of IgG ingredients sourced from cow’s milk in functional foods aimed at increasing numbers of health promoting bacteria in the human gut
Characterisation of nerve‐mediated ATP release from bladder detrusor muscle and its pathological implications
Background and Purpose.
To characterise the molecular mechanisms that determine variability of atropine‐resistance of nerve‐mediated contractions in human and guinea‐pig detrusor smooth muscle
Experimental Approach.
Atropine‐resistance of nerve‐mediated contractions, and the role of P2X1 receptors, was measured in isolated preparations from guinea‐pigs and also humans with or without overactive bladder syndrome, from which the mucosa was removed. Nerve‐mediated ATP release was measured directly with amperometric ATP‐sensitive electrodes. Ecto‐ATPase activity of guinea‐pig and human detrusor samples was measured in vitro by measuring the concentration‐dependent rate of ATP breakdown. The transcription of ecto‐ATPase subtypes in human samples was measured by qPCR.
Key Results
Atropine resistance was greatest in guinea‐pig detrusor, absent in human tissue from normally‐functioning bladders and intermediate in human overactive bladder. Greater atropine resistance correlated with reduction of contractions by the ATP‐diphospho‐hydrolase apyrase, directly implicating ATP in their generation. E‐NTPDase‐1 was the most abundantly transcribed ecto‐ATPase of those tested and transcription was reduced in tissue from human overactive, compared to normal, bladders. E‐NTPDase‐1 enzymatic activity was inversely related to the magnitude of atropine resistance. Nerve‐mediated ATP release was continually measured and varied with stimulation frequency over the range 1‐16 Hz.
Conclusion and Implications
Atropine‐resistance in nerve‐mediated detrusor contractions is due to ATP release and its magnitude is inversely related to E‐NTPDase‐1 activity. ATP is released under different stimulation conditions compared to acetylcholine that implies different routes for their release</p
Photometric Catalogue of Quasars and Other Point Sources in the Sloan Digital Sky Survey
We present a catalogue of about 6 million unresolved photometric detections
in the Sloan Digital Sky Survey Seventh Data Release classifying them into
stars, galaxies and quasars. We use a machine learning classifier trained on a
subset of spectroscopically confirmed objects from 14th to 22nd magnitude in
the SDSS {\it i}-band. Our catalogue consists of 2,430,625 quasars, 3,544,036
stars and 63,586 unresolved galaxies from 14th to 24th magnitude in the SDSS
{\it i}-band. Our algorithm recovers 99.96% of spectroscopically confirmed
quasars and 99.51% of stars to i 21.3 in the colour window that we study.
The level of contamination due to data artefacts for objects beyond is
highly uncertain and all mention of completeness and contamination in the paper
are valid only for objects brighter than this magnitude. However, a comparison
of the predicted number of quasars with the theoretical number counts shows
reasonable agreement.Comment: 16 pages, Ref. No. MN-10-2382-MJ.R2, accepted for publication in
MNRAS Main Journal, April 201
The stellar evolution of Luminous Red Galaxies, and its dependence on colour, redshift, luminosity and modelling
We present a series of colour evolution models for Luminous Red Galaxies
(LRGs) in the 7th spectroscopic data release of the Sloan Digital Sky Survey
(SDSS), computed using the full-spectrum fitting code VESPA on high
signal-to-noise stacked spectra. The colour-evolution models are computed as a
function of colour, luminosity and redshift, and we do not a-priori assume that
LRGs constitute a uniform population of galaxies in terms of stellar evolution.
By computing star-formation histories from the fossil record, the measured
stellar evolution of the galaxies is decoupled from the survey's selection
function, which also evolves with redshift. We present these evolutionary
models computed using three different sets of Stellar Population Synthesis
(SPS) codes. We show that the traditional fiducial model of purely passive
stellar evolution of LRGs is broadly correct, but it is not sufficient to
explain the full spectral signature. We also find that higher-order corrections
to this model are dependent on the SPS used, particularly when calculating the
amount of recent star formation. The amount of young stars can be
non-negligible in some cases, and has important implications for the
interpretation of the number density of LRGs within the selection box as a
function of redshift. Dust extinction, however, is more robust to the SPS
modelling: extinction increases with decreasing luminosity, increasing
redshift, and increasing r-i colour. We are making the colour evolution tracks
publicly available at http://www.icg.port.ac.uk/~tojeiror/lrg_evolution/.Comment: 29 pages, 34 figures, re-submitted to MNRAS after addressing the
referee's repor
Radio Emission and AGN Feedback in Post-starburst Galaxies
We investigate radio-mode AGN activity among post-starburst galaxies from the
Sloan Digital Sky Survey to determine whether AGN feedback may be responsible
for the cessation of star formation. Based on radio morphology and
radio-loudness from the FIRST and NVSS data, we separate objects with radio
activity due to an AGN from ongoing residual star formation. Of 513 SDSS
galaxies with strong A-star spectra, 12 objects have 21-cm flux density above 1
mJy. These galaxies do not show optical AGN emission lines. Considering that
the lifetime of radio emission is much shorter than the typical time-scale of
the spectroscopic features of post-starburst galaxies, we conclude that the
radio-emitting AGN activity in these objects was triggered after the end of the
recent starburst, and thus cannot be an important feedback process to explain
the post-starburst phase. The radio luminosities show a positive correlation
with total galaxy stellar mass, but not with the mass of recently formed stars.
Thus the mechanical power of AGN feedback derived from the radio luminosity is
related to old stellar populations dominating the stellar mass, which in turn
are related to the masses of central supermassive black holes.Comment: 11 pages, 6 figures, accepted for publication in MNRA
A public catalogue of stellar masses, star formation and metallicity histories and dust content from the Sloan Digital Sky Survey using VESPA
We applied the VESPA algorithm to the Sloan Digital Sky Survey final data
release of the Main Galaxies and Luminous Red Galaxies samples. The result is a
catalogue of stellar masses, detailed star formation and metallicity histories
and dust content of nearly 800,000 galaxies. We make the catalogue public via a
T-SQL database, which is described in detail in this paper. We present the
results using a range of stellar population and dust models, and will continue
to update the catalogue as new and improved models are made public. The data
and documentation are currently online, and can be found at
http://www-wfau.roe.ac.uk/vespa/. We also present a brief exploration of the
catalogue, and show that the quantities derived are robust: luminous red
galaxies can be described by one to three populations, whereas a main galaxy
sample galaxy needs on average two to five; red galaxies are older and less
dusty; the dust values we recover are well correlated with measured Balmer
decrements and star formation rates are also in agreement with previous
measurements.Comment: Accepted for publication in ApJS. New and extended sections,
references added, some figures changed. Conclusions and catalogue unchange
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