2,400 research outputs found
Mafic alkaline metasomatism in the lithosphere underneath East Serbia: evidence from the study of xenoliths and the host alkali basalts
Effects of mafic alkaline metasomatism have been investigated by a combined study of the East Serbian mantle xenoliths and their host alkaline rocks. Fertile xenoliths and tiny mineral assemblages found in depleted xenoliths have been investigated. Fertile lithologies are represented by clinopyroxene (cpx)-rich lherzolite and spinel (sp)-rich olivine websterite containing Ti–Al-rich Cr-augite, Fe-rich olivine, Fe–Al-rich orthopyroxene and Al-rich spinel. Depleted xenoliths, which are the predominant lithology in the suite of East Serbian xenoliths, are harzburgite, cpx-poor lherzolite and rare Mg-rich dunite. They contain small-scale assemblages occurring as pocket-like, symplectitic or irregular, deformation-assisted accumulations of metasomatic phases, generally composed of Ti–Al- and incompatible element-rich Cr-diopside, Cr–Fe–Ti-rich spinel, altered glass, olivine, apatite, ilmenite, carbonate, feldspar, and a high-TiO2 (c. 11 wt%) phlogopite. The fertile xenoliths are too rich in Al, Ca and Fe to simply represent undepleted mantle. By contrast, their composition can be reproduced by the addition of 5–20 wt% of a basanitic melt to refractory mantle. However, textural relationships found in tiny mineral assemblages inside depleted xenoliths imply the following reaction: opx+sp1 (primary mantle Cr-spinel) ±phlogopite+Si-poor alkaline melt=Ti–Al-cpx+sp2 (metasomatic Ti-rich spinel)±ol±other minor phases. Inversion modelling, performed on the least contaminated and most isotopically uniform host basanites (87Sr/86Sr=c. 0.7031; 143Nd/144Nd=c. 0.5129), implies a source that was enriched in highly and moderately incompatible elements (c. 35–40× chondrite for U–Th–Nb–Ta, 2× chondrite for heavy rare earth elements (HREE), made up of clinopyroxene, carbonate (c. 5%), and traces of ilmenite (c. 1%) and apatite (c. 0.05%). A schematic model involves: first, percolation of CO2- and H2O-rich fluids and precipitation of metasomatic hydrous minerals; and, second, the subsequent breakdown of these hydrous minerals due to the further uplift of hot asthenospheric mantle. This model links intraplate alkaline magmatism to lithospheric mantle sources enriched by sublithospheric melts at some time in the past
A Morphological Assessment of Bovine Chondrocytes Cultured on Poly(Ethyl Methacrylate)/Tetrahydrofurfuryl Methacrylate
A heterocyclic methacrylate polymer system, PEMA/THFMA, has shown potential as a biomaterial for cartilage repair in a rabbit model and has properties making it suitable for use clinically. The ability of the polymer system, PEMA/THFMA, and a related system, PEMA/HEMA, to support chondrocytes in vitro was assessed by scanning electron microscopy. Chondrocytes adhered to the surface of the PEMA/THFMA by day one, having a rounded morphology and clustered appearance opposed to the Thermanox® control, where the cells had spread out and become fibroblastic in appearance. The chondrocytes divided rapidly on the PEMA/ THFMA system by day three and had completely covered the surface by day seven. In contrast, chondrocytes did not adhere well to the more hydrophilic PEMA/ HEMA system. A few cells were seen on the surface by day one and by days three and seven, there was no evidence of cell growth or spreading across the surface.
In conclusion, the PEMA/THFMA system can support chondrocytes in vitro, whereas the PEMA/HEMA system does not
Mid-infrared luminosity as an indicator of the total infrared luminosity of galaxies
The infrared (IR) emission plays a crucial role for understanding the star
formation in galaxies hidden by dust. We first examined four estimators of the
IR luminosity of galaxies, L_fir (Helou et al. 1988), L_tir (Dale et al. 2001),
revised version of L_tir (Dale & Helou 2002) (we denote L_tir2), and L_ir
(Sanders & Mirabel 1996) by using the observed SEDs of well-known galaxies. We
found that L_ir provides excellent estimates of the total IR luminosity for a
variety of galaxy SEDs. The performance of L_tir2 was also found to be very
good. Using L_ir, we then statistically analyzed the IRAS PSCz galaxy sample
(Saunders et al. 2000) and found useful formulae relating the MIR monochromatic
luminosities [L(12um) and L(25um)], and L_ir. For this purpose we constructed a
subsample of 1420 galaxies with all IRAS four band (12, 25, 60, and 100um) flux
densities. We found linear relations between L_ir and MIR luminosities, L(12um)
and L(25um). The prediction error with 95-% confidence level is a factor of
4-5. Hence, these formulae are useful for the estimation of the total IR
luminosity only from 12um or 25um observations. We further tried to make an
`interpolation' formula for galaxies at 0<z<1. For this purpose we construct
the formula of the relation between 15-um luminosity and the total IR
luminosity. We conclude that the 15-um formula can be used as an estimator of
the total IR luminosity from 24um observation of galaxies at z \simeq 0.6.Comment: A&A in press, 8 pages, 9 figures, numerical errors correcte
On the secondary star of the cataclysmic variable 1RXS J094432.1+035738
We present V and Rc band photometry and optical near-infrared spectroscopy of
the cataclysmic variable 1RXS J094432.1+035738. We detected features of a cool
secondary star, which can be modeled with a red dwarf of spectral type M2 (+0.5
-1.0) V at a distance of 433 +- 100 pc.Comment: Accepted for publication in Astronomy and Astrophysic
Excitation and Disruption of a Giant Molecular Cloud by the Supernova Remnant 3C391
Using the IRAM 30-m telescope, we observed the supernova remnant 3C 391
(G31.9+0.0) and its surroundings in the CO(2-1), HCO+(1-0), CS(2-1), CS(3-2),
and CS(5-4) lines. The ambient molecular gas at the distance (9 kpc) of the
remnant comprises a giant molecular cloud whose edge is closely parallel to a
ridge of bright non-thermal radio continuum, which evidently delineates the
blast-wave into the cloud. We found that in a small (0.6 pc) portion of the
radio shell, the molecular line profiles consist of a narrow (2 km/s)
component, plus a very wide (> 20 km/s) component. Both spectral components
peak within 20" of a previously-detected OH 1720 MHz maser. We name this source
3C 391:BML (broad molecular line); it provides a new laboratory, similar to IC
443 but on a larger scale, to study shock interactions with dense molecular
gas. The wide spectral component is relatively brighter in the
higher-excitation lines. We interpret the wide spectral component as post-shock
gas, either smoothly accelerated or partially dissociated and reformed behind
the shock. The narrow component is either the pre-shock gas or cold gas
reformed behind a fully dissociative shock. Using the 3 observed CS lines, we
measured the temperature, CS column density, and H2 volume density in a dense
clump in the parent molecular cloud as well as the wide-line and narrow-line
portions of the shocked clump. The physical conditions of the narrow-line gas
are comparable to the highest-density clumps in the giant molecular cloud,
while the wide-line gas is both warmer and denser. The mass of compressed gas
in 3C 391:BML is high enough that its self-gravity is significant, and
eventually it could form one or several stars
Chandra Observations of G11.2-0.3: Implications for Pulsar Ages
We present Chandra X-ray Observatory imaging observations of the young
Galactic supernova remnant G11.2-0.3. The image shows that the previously known
young 65-ms X-ray pulsar is at position (J2000) RA 18h 11m 29.22s, DEC -19o 25'
27.''6, with 1 sigma error radius 0.''6. This is within 8'' of the geometric
center of the shell. This provides strong confirming evidence that the system
is younger, by a factor of ~12, than the characteristic age of the pulsar. The
age discrepancy suggests that pulsar characteristic ages can be poor age
estimators for young pulsars. Assuming conventional spin down with constant
magnetic field and braking index, the most likely explanation for the age
discrepancy in G11.2-0.3 is that the pulsar was born with a spin period of ~62
ms. The Chandra image also reveals, for the first time, the morphology of the
pulsar wind nebula. The elongated hard-X-ray structure can be interpreted as
either a jet or a Crab-like torus seen edge on. This adds to the growing list
of highly aspherical pulsar wind nebulae and argues that such structures are
common around young pulsars.Comment: 16 pages, 3 figures, Accepted for publication in ApJ. For a full
resolution version of Fig 1, see
http://www.physics.mcgill.ca/~vkaspi/G11.2-0.3/f1.ep
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Adapting domestic abuse training to remote delivery during the COVID-19 pandemic: perspectives from general practice and support services
BACKGROUND: Identifying and responding to patients affected by domestic violence and abuse (DVA) is vital in primary care. There may have been a rise in the reporting of DVA cases during the COVID-19 pandemic and associated lockdown measures. Concurrently general practice adopted remote working that extended to training and education. IRIS (Identification and Referral to Improve Safety) is an example of an evidence-based UK healthcare training support and referral programme, focusing on DVA. IRIS transitioned to remote delivery during the pandemic.
AIM: To understand the adaptations and impact of remote DVA training in IRIS-trained general practices by exploring perspectives of those delivering and receiving training.
DESIGN AND SETTING: Qualitative interviews and observation of remote training of general practice teams in England were undertaken.
METHOD: Semi-structured interviews were conducted with 21 participants (three practice managers, three reception and administrative staff, eight general practice clinicians, and seven specialist DVA staff), alongside observation of eight remote training sessions. Analysis was conducted using a framework approach.
RESULTS: Remote DVA training in UK general practice widened access to learners. However, it may have reduced learner engagement compared with face-to-face training and may challenge safeguarding of remote learners who are domestic abuse survivors. DVA training is integral to the partnership between general practice and specialist DVA services, and reduced engagement risks weakening this partnership.
CONCLUSION: The authors recommend a hybrid DVA training model for general practice, including remote information delivery alongside a structured face-to-face element. This has broader relevance for other specialist services providing training and education in primary care
Variability of Hot Supergiant IRAS 19336-0400 in the Early Phase of its Planetary Nebula Ionization
We present photoelectric and spectral observations of a hot candidate
proto-planetary nebula - early B-type supergiant with emission lines in
spectrum - IRAS 19336-0400. The light and color curves display fast irregular
brightness variations with maximum amplitudes Delta V=0.30 mag, Delta B=0.35
mag, Delta U=0.40 mag and color-brightness correlations. By the variability
characteristics IRAS 19336-0400 appears similar to other hot proto-planetary
nebulae. Based on low-resolution spectra in the range lambda 4000-7500 A we
have derived absolute intensities of the emission lines H_alpha, H_beta,
H_gamma, [SII], [NII], physical conditions in gaseous nebula: n_e=10^4 cm^{-3},
T_e=7000 \pm 1000 K. The emission line H_alpha, H_beta equivalent widths are
found to be considerably variable and related to light changes. By
UBV-photometry and spectroscopy the color excess has been estimated:
E_{B-V}=0.50-0.54. Joint photometric and spectral data analysis allows us to
assume that the star variability is caused by stellar wind variations.Comment: 11 pages, 6 figures, 2 tables, accepted for publication in Pis'ma
Astron. Zh. (Astronomy Letters
Measuring space-time variation of the fundamental constants with redshifted submillimetre transitions of neutral carbon
We compare the redshifts of neutral carbon and carbon monoxide in the
redshifted sources in which the fine structure transition of neutral carbon,
[CI], has been detected, in order to measure space-time variation of the
fundamental constants. Comparison with the CO rotational lines measures gives
the same combination of constants obtained from the comparison fine structure
line of singly ionised carbon, [CII]. However, neutral carbon has the distinct
advantage that it may be spatially coincident with the carbon monoxide, whereas
[CII] could be located in the diffuse medium between molecular clouds, and so
any comparison with CO could be dominated by intrinsic velocity differences.
Using [CI], we obtain a mean variation of dF/F = (-3.6 +/- 8.5) x 10^-5, over z
= 2.3 - 4.1, for the eight [CI] systems, which degrades to (-1.5+/- 11) x
10^-5, over z = 2.3 - 6.4 when the two [CII] systems are included. That is,
zero variation over look-back times of 10.8-12.8 Gyr. However, the latest
optical results indicate a spatial variation in alpha, which describes a dipole
and we see the same direction in dF/F. This trend is, however, due to a single
source for which the [CI] spectrum is of poor quality. This also applies to one
of the two [CII] spectra previously used to find a zero variation in
alpha^2/mu. Quantifying this, we find an anti-correlation between |dF/F| and
the quality of the carbon detection, as measured by the spectral resolution,
indicating that the typical values of >50 km/s, used to obtain a detection, are
too coarse to reliably measure changes in the constants. From the fluxes of the
known z > 1 CO systems, we predict that current instruments are incapable of
the sensitivities required to measure changes in the constants through the
comparison of CO and carbon lines. We therefore discuss in detail the use of
ALMA for such an undertaking ... ABRIDGEDComment: Accepted for publication in Section 3 - Cosmology (including clusters
of galaxies) of Astronomy and Astrophysic
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