1,897 research outputs found
Laser-induced thermal stress and the heat shock response in neural cells
Background The Ho: YAG laser is used extensively in orthopedic surgery. It offers a minimally invasive method of ablating tissue with precision. Previous studies have explored the effects of laser use on temperature during experimental foraminoplasty. To date, there has been limited work on the effects of thermal stress on cells in this context. Material and methods Cells were exposed either to heated medium or the Ho: YAG laser in the high-power mode. Heated medium was used as a stressor by (I) exposing groups of cells to a constant temperature of 45°C for varying lengths of time: 5, 10, 15 and 20 min, and (II) exposing cells for a fixed length of time (5 min) to varying temperatures: 45°C, 55°C, 65°C with a control treated at 37°C. A third group was subjected to direct laser treatment. The effects of the treatments were assessed using trypan blue staining as a measure of viability and immunocytochemistry was used to measure changes in heat shock protein (HSP) expression. Results There was a negative correlation between cell viability and HSP expression, and between cell viability and the severity of the treatment. Interpretation Our findings suggest a possible role for the Ho: YAG laser in spinal foraminoplasty based on the high level of cell viability in the treatment regimen that most closely mirrored the clinical application of the laser
Interdisciplinary study of warm core ring physics, chemistry, and biology
We are conducting an interdisciplinary study of the structure and
dynamics of Gulf Stream \Warm Core Rings by a time series investigation of
selected rings. This program consists of highly integrated components
which include physical, chemical, and biological investigation and
modeling studies. These components are designed to provide information
on the structure of rings and exchange mechanisms at ring boundaries, on their marine chemistry, and on the environmental controls of biological
activity of selected constituents associated with Warm Core Rings. This
research is being conducted by approximately two dozen investigators from
thirteen marine institutions. An interdisciplinary program of the scope
proposed is required in order to understand the interdependence among
biological, chemical, and physical processes in the ocean. This study of
the structure and evolution of Warm Core Rings will enhance the understanding
of fundamental oceanic processes and the role of rings in the
region where they occur
Analysis of lesion localisation at colonoscopy: outcomes from a multi-centre U.K. study
Background:
Colonoscopy is currently the gold standard for detection of colorectal lesions, but may be limited in anatomically localising lesions. This audit aimed to determine the accuracy of colonoscopy lesion localisation, any subsequent changes in surgical management and any potentially influencing factors.
Methods:
Patients undergoing colonoscopy prior to elective curative surgery for colorectal lesion/s were included from 8 registered U.K. sites (2012–2014). Three sets of data were recorded: patient factors (age, sex, BMI, screener vs. symptomatic, previous abdominal surgery); colonoscopy factors (caecal intubation, scope guide used, colonoscopist accreditation) and imaging modality. Lesion localisation was standardised with intra-operative location taken as the gold standard. Changes to surgical management were recorded.
Results:
364 cases were included; majority of lesions were colonic, solitary, malignant and in symptomatic referrals. 82% patients had their lesion/s correctly located at colonoscopy. Pre-operative CT visualised lesion/s in only 73% of cases with a reduction in screening patients (64 vs. 77%; p = 0.008). 5.2% incorrectly located cases at colonoscopy underwent altered surgical management, including conversion to open. Univariate analysis found colonoscopy accreditation, scope guide use, incomplete colonoscopy and previous abdominal surgery significantly influenced lesion localisation. On multi-variate analysis, caecal intubation and scope guide use remained significant (HR 0.35, 0.20–0.60 95% CI and 0.47; 0.25–0.88, respectively).
Conclusion:
Lesion localisation at colonoscopy is incorrect in 18% of cases leading to potentially significant surgical management alterations. As part of accreditation, colonoscopists need lesion localisation training and awareness of when inaccuracies can occur
Ureter tracking and segmentation in CT urography (CTU) using COMPASS
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134875/1/mp1412_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134875/2/mp1412.pd
The Redshift One LDSS-3 Emission line Survey (ROLES) II: Survey method and z~1 mass-dependent star-formation rate density
Motivated by suggestions of 'cosmic downsizing', in which the dominant
contribution to the cosmic star formation rate density (SFRD) proceeds from
higher to lower mass galaxies with increasing cosmic time, we describe the
design and implementation of the Redshift One LDSS3 Emission line Survey
(ROLES). ROLES is a K-selected (22.5 < K_AB < 24.0) survey for dwarf galaxies
[8.5<log(M*/Msun)< 9.5] at 0.89 < z < 1.15 drawn from two extremely deep fields
(GOODS-S and MS1054-FIRES). Using the [OII]3727 emission line, we obtain
redshifts and star-formation rates (SFRs) for star-forming galaxies down to a
limit of ~0.3 Msun/yr. We present the [OII] luminosity function measured in
ROLES and find a faint end slope of alpha_faint ~ -1.5, similar to that
measured at z~0.1 in the SDSS. By combining ROLES with higher mass surveys, we
measure the SFRD as a function of stellar mass using [OII] (with and without
various empirical corrections), and using SED-fitting to obtain the SFR from
the rest-frame UV luminosity for galaxies with spectroscopic redshifts. Our
best estimate of the corrected [OII]-SFRD and UV SFRD both independently show
that the SFRD evolves equally for galaxies of all masses between z~1 and z~0.1.
The exact evolution in normalisation depends on the indicator used, with the
[OII]-based estimate showing a change of a factor of ~2.6 and the UV-based a
factor of ~6. We discuss possible reasons for the discrepancy in normalisation
between the indicators, but note that the magnitude of this uncertainty is
comparable to the discrepancy between indicators seen in other z~1 works. Our
result that the shape of the SFRD as a function of stellar mass (and hence the
mass range of galaxies dominating the SFRD) does not evolve between z~1 and
z~0.1 is robust to the choice of indicator. [abridged]Comment: Resubmitted to MNRAS following first referee report. 20 pages, 16
figures. High resolution version available at
http://astro.uwaterloo.ca/~dgilbank/papers/roles2.pd
The Sloan Digital Sky Survey Quasar Lens Search. IV. Statistical Lens Sample from the Fifth Data Release
We present the second report of our systematic search for strongly lensed
quasars from the data of the Sloan Digital Sky Survey (SDSS). From extensive
follow-up observations of 136 candidate objects, we find 36 lenses in the full
sample of 77,429 spectroscopically confirmed quasars in the SDSS Data Release
5. We then define a complete sample of 19 lenses, including 11 from our
previous search in the SDSS Data Release 3, from the sample of 36,287 quasars
with i<19.1 in the redshift range 0.6<z<2.2, where we require the lenses to
have image separations of 1"<\theta<20" and i-band magnitude differences
between the two images smaller than 1.25 mag. Among the 19 lensed quasars, 3
have quadruple-image configurations, while the remaining 16 show double images.
This lens sample constrains the cosmological constant to be
\Omega_\Lambda=0.84^{+0.06}_{-0.08}(stat.)^{+0.09}_{-0.07}(syst.) assuming a
flat universe, which is in good agreement with other cosmological observations.
We also report the discoveries of 7 binary quasars with separations ranging
from 1.1" to 16.6", which are identified in the course of our lens survey. This
study concludes the construction of our statistical lens sample in the full
SDSS-I data set.Comment: 37 pages, 2 figures and 5 tables, accepted to A
Baryon Acoustic Oscillations in the Sloan Digital Sky Survey Data Release 7 Galaxy Sample
The spectroscopic Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) galaxy
sample represents the final set of galaxies observed using the original SDSS
target selection criteria. We analyse the clustering of galaxies within this
sample, including both the Luminous Red Galaxy (LRG) and Main samples, and also
include the 2-degree Field Galaxy Redshift Survey (2dFGRS) data. Baryon
Acoustic Oscillations are observed in power spectra measured for different
slices in redshift; this allows us to constrain the distance--redshift relation
at multiple epochs. We achieve a distance measure at redshift z=0.275, of
r_s(z_d)/D_V(0.275)=0.1390+/-0.0037 (2.7% accuracy), where r_s(z_d) is the
comoving sound horizon at the baryon drag epoch,
D_V(z)=[(1+z)^2D_A^2cz/H(z)]^(1/3), D_A(z) is the angular diameter distance and
H(z) is the Hubble parameter. We find an almost independent constraint on the
ratio of distances D_V(0.35)/D_V(0.2)=1.736+/-0.065, which is consistent at the
1.1sigma level with the best fit Lambda-CDM model obtained when combining our
z=0.275 distance constraint with the WMAP 5-year data. The offset is similar to
that found in previous analyses of the SDSS DR5 sample, but the discrepancy is
now of lower significance, a change caused by a revised error analysis and a
change in the methodology adopted, as well as the addition of more data. Using
WMAP5 constraints on Omega_bh^2 and Omega_ch^2, and combining our BAO distance
measurements with those from the Union Supernova sample, places a tight
constraint on Omega_m=0.286+/-0.018 and H_0 = 68.2+/-2.2km/s/Mpc that is robust
to allowing curvature and non-Lambda dark energy. This result is independent of
the behaviour of dark energy at redshifts greater than those probed by the BAO
and supernova measurements. (abridged)Comment: 22 pages, 16 figures, minor changes to match version published in
MNRA
The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
We present the fifth edition of the Sloan Digital Sky Survey (SDSS) Quasar
Catalog, which is based upon the SDSS Seventh Data Release. The catalog, which
contains 105,783 spectroscopically confirmed quasars, represents the conclusion
of the SDSS-I and SDSS-II quasar survey. The catalog consists of the SDSS
objects that have luminosities larger than M_i = -22.0 (in a cosmology with H_0
= 70 km/s/Mpc Omega_M = 0.3, and Omega_Lambda = 0.7) have at least one emission
line with FWHM larger than 1000 km/s or have interesting/complex absorption
features, are fainter than i > 15.0 and have highly reliable redshifts. The
catalog covers an area of 9380 deg^2. The quasar redshifts range from 0.065 to
5.46, with a median value of 1.49; the catalog includes 1248 quasars at
redshifts greater than four, of which 56 are at redshifts greater than five.
The catalog contains 9210 quasars with i < 18; slightly over half of the
entries have i< 19. For each object the catalog presents positions accurate to
better than 0.1" rms per coordinate, five-band (ugriz) CCD-based photometry
with typical accuracy of 0.03 mag, and information on the morphology and
selection method. The catalog also contains radio, near-infrared, and X-ray
emission properties of the quasars, when available, from other large-area
surveys. The calibrated digital spectra cover the wavelength region 3800-9200
Ang. at a spectral resolution R = 2000 the spectra can be retrieved from the
SDSS public database using the information provided in the catalog. Over 96% of
the objects in the catalog were discovered by the SDSS. We also include a
supplemental list of an additional 207 quasars with SDSS spectra whose archive
photometric information is incomplete.Comment: Accepted, to appear in AJ, 7 figures, electronic version of Table 2
is available, see
http://www.sdss.org/dr7/products/value_added/qsocat_dr7.htm
Calcium Homeostasis in Myogenic Differentiation Factor 1 (MyoD)-Transformed, Virally-Transduced, Skin-Derived Equine Myotubes
Dysfunctional skeletal muscle calcium homeostasis plays a central role in the pathophysiology of several human and animal skeletal muscle disorders, in particular, genetic disorders associated with ryanodine receptor 1 (RYR1) mutations, such as malignant hyperthermia, central core disease, multiminicore disease and certain centronuclear myopathies. In addition, aberrant skeletal muscle calcium handling is believed to play a pivotal role in the highly prevalent disorder of Thoroughbred racehorses, known as Recurrent Exertional Rhabdomyolysis. Traditionally, such defects were studied in human and equine subjects by examining the contractile responses of biopsied muscle strips exposed to caffeine, a potent RYR1 agonist. However, this test is not widely available and, due to its invasive nature, is potentially less suitable for valuable animals in training or in the human paediatric setting. Furthermore, increasingly, RYR1 gene polymorphisms (of unknown pathogenicity and significance) are being identified through next generation sequencing projects. Consequently, we have investigated a less invasive test that can be used to study calcium homeostasis in cultured, skin-derived fibroblasts that are converted to the muscle lineage by viral transduction with a MyoD (myogenic differentiation 1) transgene. Similar models have been utilised to examine calcium homeostasis in human patient cells, however, to date, there has been no detailed assessment of the cells’ calcium homeostasis, and in particular, the responses to agonists and antagonists of RYR1. Here we describe experiments conducted to assess calcium handling of the cells and examine responses to treatment with dantrolene, a drug commonly used for prophylaxis of recurrent exertional rhabdomyolysis in horses and malignant hyperthermia in humans
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