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  • 1
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    HCN hyperfine ratio analysis of massive molecular clumps (2016)
    Oxford University Press
    Details
    Publication Date: 2016-12-16
    Description: We report a new analysis protocol for HCN hyperfine data, based on the PySpecKit package, and results of using this new protocol to analyse a sample area of seven massive molecular clumps from the Census of High- and Medium-mass Protostars (CHaMP) survey, in order to derive maps of column density for this species. There is a strong correlation between the HCN integrated intensity, I HCN , and previously reported $I_{\rm HCO^{+}}$ in the clumps, but $I_{\rm N_{2}H^{+}}$ is not well correlated with either of these other two ‘dense gas tracers’. The four fitted parameters from PySpecKit in this region fall in the range of V LSR = 8–10 km s –1 , V = 1.2–2.2 km s –1 , T ex = 4–15 K, and = 0.2–2.5. These parameters allow us to derive a column density map of these clouds, without limiting assumptions about the excitation or opacity. A more traditional (linear) method of converting I HCN to total mass column gives much lower clump masses than our results based on the hyperfine analysis. This is primarily due to areas in the sample region of low I , low T ex , and high . We conclude that there may be more dense gas in these massive clumps not engaged in massive star formation than previously recognized. If this result holds for other clouds in the CHaMP sample, it would have dramatic consequences for the calibration of the Kennicutt–Schmidt star formation laws, including a large increase in the gas depletion time-scale in such regions.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 2
    Electronic Resource
    Electronic Resource
    EFFECTS OF DILUENT COMPOSITION AND TEMPERATURE ON MOTILITY AND VIABILITY AFTER LIQUID STORAGE AND CRYOPRESERVATION OF MINKE WHALE (BALAENOPTERA ACUTOROSTRATA) SPERMATOZOA (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 14 (1998), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.1998.tb00770.x
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  • 3
    Electronic Resource
    Electronic Resource
    ENDOCRINOLOGICAL OBSERVATIONS OF FEMALE MINKE WHALES (BALAENOPTERA ACUTOROSTRATA) (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 12 (1996), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.1996.tb00580.x
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  • 4
    Electronic Resource
    Electronic Resource
    RELATIONSHIPS AMONG MORPHOLOGICAL STATUS, STEROID HORMONES, AND POST-THAWING VIABILITY OF FROZEN SPERMATOZOA OF MALE MINKE WHALES (BALAENOPTERA ACUTOROSTRATA) (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 12 (1996), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Spermatozoa from 21 mature minke whales (Balaenoptera acutorostrata) taken in the Antarctic Ocean for Japanese research were recovered from vasa deferentia, diluted 1:9 in a Tris-based diluent, and frozen at - 80°C on board the vessel. After a period ranging from 45 to 125 d, the samples were transferred to liquid nitrogen and transported to the laboratory. After thawing at 37°C the motility (percentage of motile spermatozoa), vitality (proportion of live spermatozoa), and sperm concentration were determined for each sample. These values were tested for correlations with morphological measurements (body size, body weight, testis weight) and serum concentrations of progesterone (Pd), estradiol-17β (E2), and testosterone (T). Ten of 21 samples had motile spermatozoa (2%-40%). Although no motile spermatozoa were observed in 1.1 samples, all sperm samples were examined by eosinnigrosin staining and showed vitality levels of 3%44%. It was found that the motility (Y = 0.54) and vitality (r = 0.53) of the spermatozoa were significantly (P 〈 0.01) correlated with the E2 levels (8.50 ± 1.80 pg/ml). Serum T levels (0.07 ± 0.02 ngml) were significantly correlated with the E2 levels (r = 0.58, P 〈 0.01〉, but sperm concentrations were not correlated with either Ea or T levels. The present study demonstrates that spermatozoa of minke whales can be successfully cryopreserved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.1996.tb00303.x
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  • 5
    Electronic Resource
    Electronic Resource
    GLYCOSURIA AND INSULITIS IN NOD MICE EXPRESSING THE HLA-DQw6 MOLECULE (1989)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 16 (1989), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: To investigate HLA-linked genes controlling the susceptibility and resistance to insulin dependent diabetes mellitus (IDDM), HLA-DQ alleles of 45 Japanese patients with IDDM were analysed, using sequence specific oligonucleotide (SSO). DQA1*0301 and DQBI*04 were positively associated (R.R = 6.6, Pc〈0.05 and R.R. = 4.7 Pc〈0.01) and DQAI*0103 and DQBI*0104 were negatively associated (R.R. =0–2, Pc〈0.01) with IDDM. DQAI*0103 and DQB1*0104 were in strong linkage disequilibrium to encode for DQw6 molecule. Therefore, in a Japanese population, the DQw6 molecule seems to control the resistance to IDDM. To determine whether or not the DQw6 molecule itself can protect against glycosuria and insulitis in NOD mice, these animals were mated with HLA-DQw6 transgenic-C57BL/6 mice (DQw6-B6) and the F1 progeny expressing the DQw6 molecule were backcrossed with NOD mice. Eighty-five female backcross progenies were classified into four groups, according to the MHC classII phenotype; I-Anod/I-Anod DQw6(-), I-Anod/I-Anod DQw6(+), I-Anod/I-Ab DQw6(-) and I-Anod/I-Ab DQw6(+). At the age of 16 weeks, 9.1% of the DQw6(-) I-Ab(-) mice had a glycosuria whereas none of the DQw6(+) I-Ab(-) mice had a glycosuria. At the age of 30 weeks 13.6% of the DQw6(-) I-Ab(-) mice had a glycosuria and 7.7% of the DQw6(+) I-Ab(-) mice had a glycosuria. Histological examinations of the pancreas were performed in the 30 week old mice or after the development of glycosuria. About 50% of I-Ab(-) mice developed insulitis, regardless of the expression of the DQw6 molecule. Thus, the DQw6 molecule seemed to delay the onset of glycosuria but did not protect against glycosuria and insulitis in the NOD mice despite a functional expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1989.tb00493.x
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  • 6
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    Ammonia excitation imaging of shocked gas towards the W28 gamma-ray source HESS J1801-233 (2016)
    Oxford University Press
    Details
    Publication Date: 2016-08-04
    Description: We present 12 mm Mopra observations of the dense (〉10 3  cm –3 ) molecular gas towards the north-east of the W28 supernova remnant (SNR). This cloud is spatially well matched to the TeV gamma-ray source HESS J1801–233 and is known to be an SNR-molecular cloud interaction region. Shock-disruption is evident from broad NH 3 (1,1) spectral linewidths in regions towards the W28 SNR, while strong detections of spatially extended NH 3 (3,3), NH 3 (4,4) and NH 3 (6,6) inversion emission towards the cloud strengthen the case for the existence of high temperatures within the cloud. Velocity dispersion measurements and NH 3 ( n , n )/(1,1) ratio maps, where n = 2, 3, 4 and 6, indicate that the source of disruption is from the side of the cloud nearest to the W28 SNR, suggesting that it is the source of cloud-disruption. Towards part of the cloud, the ratio of ortho to para-NH 3 is observed to exceed 2, suggesting gas-phase NH 3 enrichment due to NH 3 liberation from dust-grain mantles. The measured NH 3 abundance with respect to H 2 is ~(1.2 ± 0.5) x 10 –9 , which is not high, as might be expected for a hot, dense molecular cloud enriched by sublimated grain-surface molecules. The results are suggestive of NH 3 sublimation and destruction in this molecular cloud, which is likely to be interacting with the W28 SNR shock.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 7
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    The dust properties and physical conditions of the interstellar medium in the LMC massive star-forming complex N11 (2015)
    Oxford University Press
    Details
    Publication Date: 2015-12-26
    Description: We combine Spitzer and Herschel data of the star-forming region N11 in the Large Magellanic Cloud (LMC) to produce detailed maps of the dust properties in the complex and study their variations with the interstellar-medium conditions. We also compare Atacama Pathfinder EXperiment/Large APEX Bolometer Camera (APEX/LABOCA) 870 μm observations with our model predictions in order to decompose the 870 μm emission into dust and non-dust [free–free emission and CO(3–2) line] contributions. We find that in N11, the 870 μm can be fully accounted for by these three components. The dust surface density map of N11 is combined with H  i and CO observations to study local variations in the gas-to-dust mass ratios. Our analysis leads to values lower than those expected from the LMC low-metallicity as well as to a decrease of the gas-to-dust mass ratio with the dust surface density. We explore potential hypotheses that could explain the low ‘observed’ gas-to-dust mass ratios (variations in the X CO factor, presence of CO-dark gas or of optically thick H  i or variations in the dust abundance in the dense regions). We finally decompose the local spectral energy distributions (SEDs) using a principal component analysis (i.e. with no a priori assumption on the dust composition in the complex). Our results lead to a promising decomposition of the local SEDs in various dust components (hot, warm, cold) coherent with that expected for the region. Further analysis on a larger sample of galaxies will follow in order to understand how unique this decomposition is or how it evolves from one environment to another.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 8
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    Stochastic non-circular motion and outflows driven by magnetic activity in the Galactic bulge region (2015)
    Oxford University Press
    Details
    Publication Date: 2015-10-19
    Description: By performing a global magnetohydrodynamical simulation for the Milky Way with an axisymmetric gravitational potential, we propose that spatially dependent amplification of magnetic fields possibly explains the observed noncircular motion of the gas in the Galactic centre region. The radial distribution of the rotation frequency in the bulge region is not monotonic in general. The amplification of the magnetic field is enhanced in regions with stronger differential rotation, because magnetorotational instability and field-line stretching are more effective. The strength of the amplified magnetic field reaches 0.5 mG, and radial flows of the gas are excited by the inhomogeneous transport of angular momentum through turbulent magnetic field that is amplified in a spatially dependent manner. In addition, the magnetic pressure-gradient force also drives radial flows in a similar manner. As a result, the simulated position–velocity diagram exhibits a time-dependent asymmetric parallelogram-shape owing to the intermittency of the magnetic turbulence; the present model provides a viable alternative to the bar-potential-driven model for the parallelogram shape of the central molecular zone. This is a natural extension into the central few 100 pc of the magnetic activity, which is observed as molecular loops at radii from a few 100 pc to 1 kpc. Furthermore, the time-averaged net gas flow is directed outward, whereas the flows are highly time dependent, which we discuss from a viewpoint of the outflow from the bulge.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 9
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    Isolating signatures of major cloud-cloud collisions using position-velocity diagrams (2015)
    Oxford University Press
    Details
    Publication Date: 2015-04-16
    Description: Collisions between giant molecular clouds are a potential mechanism for triggering the formation of massive stars, or even super star clusters. The trouble is identifying this process observationally and distinguishing it from other mechanisms. We produce synthetic position–velocity diagrams from models of cloud–cloud collisions, non-interacting clouds along the line of sight, clouds with internal radiative feedback and a more complex cloud evolving in a galactic disc, to try and identify unique signatures of collision. We find that a broad bridge feature connecting two intensity peaks, spatially correlated but separated in velocity, is a signature of a high-velocity cloud–cloud collision. We show that the broad bridge feature is resilient to the effects of radiative feedback, at least to around 2.5 Myr after the formation of the first massive (ionizing) star. However for a head-on 10 km s –1 collision, we find that this will only be observable from 20 to 30 per cent of viewing angles. Such broad–bridge features have been identified towards M20, a very young region of massive star formation that was concluded to be a site of cloud–cloud collision by Torii et al., and also towards star formation in the outer Milky Way by Izumi et al.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 10
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    Isolating signatures of major cloud-cloud collisions - II. The lifetimes of broad bridge features (2015)
    Oxford University Press
    Details
    Publication Date: 2015-10-08
    Description: We investigate the longevity of broad bridge features in position–velocity diagrams that appear as a result of cloud–cloud collisions. Broad bridges will have a finite lifetime due to the action of feedback, conversion of gas into stars and the time-scale of the collision. We make a series of analytic arguments with which to estimate these lifetimes. Our simple analytic arguments suggest that for collisions between clouds larger than R  ~ 10 pc the lifetime of the broad bridge is more likely to be determined by the lifetime of the collision rather than the radiative or wind feedback disruption time-scale. However, for smaller clouds feedback becomes much more effective. This is because the radiative feedback time-scale scales with the ionizing flux N ly as $R^{7/4}N_{{\rm ly}}^{-1/4}$ so a reduction in cloud size requires a relatively large decrease in ionizing photons to maintain a given time-scale. We find that our analytic arguments are consistent with new synthetic observations of numerical simulations of cloud–cloud collisions (including star formation and radiative feedback). We also argue that if the number of observable broad bridges remains ~ constant, then the disruption time-scale must be roughly equivalent to the collision rate. If this is the case, our analytic arguments also provide collision rate estimates, which we find are readily consistent with previous theoretical models at the scales they consider (clouds larger than about 10 pc) but are much higher for smaller clouds.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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