314 research outputs found
The prevalence and morphometric features of mastoid emissary vein on multidetector computed tomography
Background: The aim of the study was to evaluate the prevalence and morphometric features of mastoid emissary vein (MEV) on multidetector computed tomography (MDCT) scans, emphasize its clinical significance and review its surgical implications.
Materials and methods: Cranial and temporal bone MDCTs of 248 patients (496 sides) were analysed by 2 radiologists. Mastoid foramen (MF) was defined on the 3 dimensional volume rendered (3DVR) images. The MF and mastoid emissary canal (MEC) were investigated in axial thin slices and the diameters of the largest MF and MEC were measured. Mean diameters of MF and MEC were determined. The number of the mastoid foramina was noted. Differences in MF prevalence by sex and side were evaluated.
Results: The overall prevalence of MEC was 92.3%. It was observed in 91.5% of women and 93.3% of men. MEC was present on the right side in 84.7% and on the left side in 82.3% of temporal bones. The mean diameter of MF was 1.92 ± ± 1.02 mm on the right and 1.84 ± 0.98 mm on the left. In both sides the number of the MF’s changed from absent to triple. The mean diameter of MEC was 1.58 ± 0.86 mm on the right and 1.48 ± 0.79 mm on the left side. The mean diameter of MEC was significantly larger in men. No significant correlation was detected between age and the MEC diameter.
Conclusions: The preoperative detection of mastoid emissary veins is necessary. The radiologists should be familiar with their clinical significance and variant appearances and report them accurately. Knowledge of their morphology and surgical implications by the surgeons will make them aware to avoid unexpected and fatal complications while operating in the suboccipital and mastoid area. MDCT is a reliable diagnostic tool for imaging the MEC and MF.
Tulathromycin disturbs blood oxidative and coagulation status
The aim of this study was to determine the effect of tulathromycin on serum oxidative status and coagulation factors in rabbits. Tulathromycin was administered to eight rabbits, and blood samples were obtained 0, 1, 5, 10 and 15 days after treatment. Indicators of serum oxidative status (malondialdehyde, nitric oxide, superoxide dismutase, retinol and -carotene) and coagulation values (antithrombin III, fibrinogen) were measured after tulathromycin treatment. In addition, routine serum biochemical values (creatine kinase-MB, lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, gamma glutamyl transferase, creatinine, blood urea nitrogen, cholesterol, triglyceride, high density lipoprotein, amylase, total protein, albumin, glucose and calcium), haemacell counts (white and red blood cells) and arterial blood gas parameters (packed cell volume, hemoglobin, pH, partial pressure of carbon dioxide, partial pressure of oxygen, actual bicarbonate, standard bicarbonate, total carbon dioxide, base excess in vivo, base excess in vitro, oxygen saturation, sodium and potassium) were also determined. Tulathromycin increased (P < 0.05) the levels of malondialdehyde, nitric oxide and superoxide dismutase activity, and decreased (P < 0.05) the level of antithrombin III. In conclusion, tulathromycin may cause oxidative damage and coagulation disorders during the treatment period.Key words: Tulathromycin, oxidative damage, coagulation disorder
Segregation of Polymers in Confined Spaces
We investigate the motion of two overlapping polymers with self-avoidance
confined in a narrow 2d box. A statistical model is constructed using blob
free-energy arguments. We find spontaneous segregation under the condition: , and mixing under , where L is the length of the box, and
the polymer extension in an infinite slit. Segregation time scales are
determined by solving a mean first-passage time problem, and by performing
Monte Carlo simulations. Predictions of the two methods show good agreement.
Our results may elucidate a driving force for chromosomes segregation in
bacteria
The Effect of Helium Sedimentation on Galaxy Cluster Masses and Scaling Relations
Recent theoretical studies predict that the inner regions of galaxy clusters
may have an enhanced helium abundance due to sedimentation over the cluster
lifetime. If sedimentation is not suppressed (e.g., by tangled magnetic
fields), this may significantly affect the cluster mass estimates. We use
Chandra X-ray observations of eight relaxed galaxy clusters to investigate the
upper limits to the effect of helium sedimentation on the measurement of
cluster masses and the best-fit slopes of the Y_X - M_500 and Y_X - M_2500
scaling relations. We calculated gas mass and total mass in two limiting cases:
a uniform, un-enhanced abundance distribution and a radial distribution from
numerical simulations of helium sedimentation on a timescale of 11 Gyrs. The
assumed helium sedimentation model, on average, produces a negligible increase
in the gas mass inferred within large radii (r < r500) (1.3 +/- 1.2 per cent)
and a (10.2 +/- 5.5) per cent mean decrease in the total mass inferred within r
< r500. Significantly stronger effects in the gas mass (10.5 +/- 0.8 per cent)
and total mass (25.1 +/- 1.1 per cent) are seen at small radii owing to a
larger variance in helium abundance in the inner region, r < 0.1 r500. We find
that the slope of the Y_X -M_500 scaling relation is not significantly affected
by helium sedimentation.Comment: 11 pages, accepted for publication in Astronomy and Astrophysic
The Evolution of the Intracluster Medium Metallicity in Sunyaev-Zel'dovich-Selected Galaxy Clusters at 0 < z < 1.5
We present the results of an X-ray spectral analysis of 153 galaxy clusters
observed with the Chandra, XMM-Newton, and Suzaku space telescopes. These
clusters, which span 0 < z < 1.5, were drawn from a larger, mass-selected
sample of galaxy clusters discovered in the 2500 square degree South Pole
Telescope Sunyaev Zel'dovich (SPT-SZ) survey. With a total combined exposure
time of 9.1 Ms, these data yield the strongest constraints to date on the
evolution of the metal content of the intracluster medium (ICM). We find no
evidence for strong evolution in the global (r<R500) ICM metallicity (dZ/dz =
-0.06 +/- 0.04 Zsun), with a mean value at z=0.6 of = 0.23 +/- 0.01 Zsun
and a scatter of 0.08 +/- 0.01 Zsun. These results imply that >60% of the
metals in the ICM were already in place at z=1 (at 95% confidence), consistent
with the picture of an early (z>1) enrichment. We find, in agreement with
previous works, a significantly higher mean value for the metallicity in the
centers of cool core clusters versus non-cool core clusters. We find weak
evidence for evolution in the central metallicity of cool core clusters (dZ/dz
= -0.21 +/- 0.11 Zsun), which is sufficient to account for this enhanced
central metallicity over the past ~10 Gyr. We find no evidence for metallicity
evolution outside of the core (dZ/dz = -0.03 +/- 0.06 Zsun), and no significant
difference in the core-excised metallicity between cool core and non-cool core
clusters. This suggests that strong radio-mode AGN feedback does not
significantly alter the distribution of metals at r>0.15R500. Given the
limitations of current-generation X-ray telescopes in constraining the ICM
metallicity at z>1, significant improvements on this work will likely require
next-generation X-ray missions.Comment: 11 pages, 8 figures, 2 tables. Submitted to ApJ. Comments welcome
Frontier fields clusters: deep Chandra observations of the complex merger MACS~J1149.6+2223
The Hubble Space Telescope Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist of four dark matter halos. We present results from deep (365 ks) Chandra observations of the cluster, which reveal the most distant cold front (z = 0.544) discovered to date. In the cluster outskirts, we also detect hints of a surface brightness edge that could be the bow shock preceding the cold front. The substructure analysis of the cluster identified several components with large relative radial velocities, thus indicating that at least some collisions occur almost along the line of sight. The inclination of the mergers with respect to the plane of the sky poses significant observational challenges at X-ray wavelengths. MACS J1149.6+2223 possibly hosts a steep-spectrum radio halo. If the steepness of the radio halo is confirmed, then the radio spectrum, combined with the relatively regular ICM morphology, could indicate that MACS J1149.6+2223 is an old merging cluster
The discovery of lensed radio and x-ray sources behind the frontier fields cluster MACS J0717.5+3745 with the JVLA and Chandra
© 2016. The American Astronomical Society. All rights reserved.. We report on high-resolution JVLA and Chandra observations of the Hubble Space Telescope (HST) Frontier Cluster MACS J0717.5+3745. MACS J0717.5+3745 offers the largest contiguous magnified area of any known cluster, making it a promising target to search for lensed radio and X-ray sources. With the high-resolution 1.0-6.5 GHz JVLA imaging in A and B configuration, we detect a total of 51 compact radio sources within the area covered by the HST imaging. Within this sample, we find seven lensed sources with amplification factors larger than two. None of these sources are identified as multiply lensed. Based on the radio luminosities, the majority of these sources are likely star-forming galaxies with star-formation rates (SFRs) of 10-50 yr -1 located at . Two of the lensed radio sources are also detected in the Chandra image of the cluster. These two sources are likely active galactic nuclei, given their 2-10 keV X-ray luminosities of ∼10 43-44 erg s -1 . From the derived radio luminosity function, we find evidence for an increase in the number density of radio sources at , compared to a sample. Our observations indicate that deep radio imaging of lensing clusters can be used to study star-forming galaxies, with SFRs as low as ∼10 M o yr -1 , at the peak of cosmic star formation history
Discovery of the lensed quasar eRASS1 J050129.5-073309 with eROSITA and
We report the discovery and spectroscopic identification of the bright doubly
lensed quasar eRASS1 J050129.5-073309 at redshift , selected from the
first all-sky survey of the eROSITA
telescope and the EDR3 catalog. We systematically search for
extragalactic sources with eROSITA X-ray positions having multiple
counterparts and have started spectroscopic follow-up of the most promising
candidates using long-slit spectroscopy with NTT/EFOSC2 to confirm the lens
nature. The two images are separated by and their average
-band magnitudes are 16.95 and 17.33. Legacy Survey DR10 imaging and
image modeling reveal both the lensing galaxy and tentatively the lensed image
of the quasar host galaxy. Archival optical light curves show evidence of a
variability time delay with the fainter component lagging the brighter by about
100 days. The fainter image has also decreased its brightness by about 1
magnitude since 2019. This dimming was still obvious at the time of the
spectroscopic observations and is probably caused by microlensing. The optical
spectroscopic follow-up obtained from NTT/EFOSC2 and the evidence provided by
the imaging and timing analysis allow us to confirm the lensed nature of eRASS1
J050129.5-073309.Comment: Accepted for publication in A&
Resolving the merging planck cluster plck G147.3-16.6 with gismo
The Planck satellite has recently completed an all-sky galaxy cluster survey exploiting the thermal Sunyaev-Zel'dovich (SZ) effect to locate some of the most massive systems observable. With a median redshift of , the clusters found by Planck at are proving to be exceptionally massive and/or disturbed systems. One notable Planck discovery at z = 0.645, PLCK G147.3-16.6, has an elongated core and hosts a radio halo, indicating it is likely in the process of merging. We present a 16.?5 resolution SZ observation of this high-z merger using the Goddard-IRAM Superconducting 2-Millimeter Observer, and compare it to X-ray follow-up observations with XMM-Newton. We find the SZ pressure substructure is offset from the core components seen in X-ray. We interpret this as possible line of sight temperature or density substructure due to the on-going merger
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