The Mass-Size Relation from Clouds to Cores. I. A new Probe of Structure in Molecular Clouds

We use a new contour-based map analysis technique to measure the mass and size of molecular cloud fragments continuously over a wide range of spatial scales (0.05 < r / pc < 10), i.e., from the scale of dense cores to those of entire clouds. The present paper presents the method via a detailed exploration of the Perseus Molecular Cloud. Dust extinction and emission data are combined to yield reliable scale-dependent measurements of mass. This scale-independent analysis approach is useful for several reasons. First, it provides a more comprehensive characterization of a map (i.e., not biased towards a particular spatial scale). Such a lack of bias is extremely useful for the joint analysis of many data sets taken with different spatial resolution. This includes comparisons between different cloud complexes. Second, the multi-scale mass-size data constitutes a unique resource to derive slopes of mass-size laws (via power-law fits). Such slopes provide singular constraints on large-scale density gradients in clouds.Comment: accepted to ApJ; references updated in new versio

Distribution and mass of diffuse and dense CO gas in the Milky Way

This is the final version of the article. Available from American Astronomical Society and IOP Publishing via the DOI in this record.Emission from carbon monoxide (CO) is ubiquitously used as a tracer of dense star-forming molecular clouds. There is, however, growing evidence that a significant fraction of CO emission originates from diffuse molecular gas. Quantifying the contribution of diffuse CO-emitting gas is vital for understanding the relation between molecular gas and star formation. We examine the Galactic distribution of two CO-emitting gas components, a high column density component detected in 13CO and 12CO, and a low column density component detected in 12CO, but not in 13CO. The “diffuse” and “dense” components are identified using a combination of smoothing, masking, and erosion/dilation procedures, making use of three large-scale 12CO and 13CO surveys of the inner and outer Milky Way. The diffuse component, which globally represents 25% (1.5 × 108M⊙) of the total molecular gas mass (6.5 × {10}8 M⊙), is more extended perpendicular to the Galactic plane. The fraction of diffuse gas increases from ∼10%–20% at a galactocentric radius of 3–4 kpc to 50% at 15 kpc, and increases with decreasing surface density. In the inner Galaxy, a yet denser component traced by CS emission represents 14% of the total molecular gas mass traced by 12CO emission. Only 14% of the molecular gas mass traced by 12CO emission is identified as part of molecular clouds in 13CO surveys by cloud identification algorithms. This study indicates that CO emission not only traces star-forming clouds, but also a significant diffuse molecular ISM component.R.S. and R.S.K. acknowledge support from the Deutsche Forschungsgemeinschaft (DFG) for funding through the SPP 1573 “The Physics of the Interstellar Medium” as well as via SFB 881 “The Milky Way System” (sub-projects B12, and B8). R.S.K. also receives funding from the European Research Council under the European Communitys Seventh Framework Program (FP7/2007-2013) via the ERC Advanced Grant “STARLIGHT” (project number 339177)

Radial Dependence of the Pattern Speed of M51

The grand-design spiral galaxy M51 has long been a crucial target for theories of spiral structure. Studies of this iconic spiral can address the question of whether strong spiral structure is transient (e.g. interaction-driven) or long-lasting. As a clue to the origin of the structure in M51, we investigate evidence for radial variation in the spiral pattern speed using the radial Tremaine-Weinberg (TWR) method. We implement the method on CO observations tracing the ISM-dominant molecular component. Results from the method's numerical implementation--combined with regularization, which smooths intrinsically noisy solutions--indicate two distinct patterns speeds inside 4 kpc at our derived major axis PA=170 deg., both ending at corotation and both significantly higher than the conventionally adopted global value. Inspection of the rotation curve suggests that the pattern speed interior to 2 kpc lacks an ILR, consistent with the leading structure seen in HST near-IR observations. We also find tentative evidence for a lower pattern speed between 4 and 5.3 kpc measured by extending the regularized zone. As with the original TW method, uncertainty in major axis position angle (PA) is the largest source of error in the calculation; in this study, where \delta PA=+/-5 deg. a ~20% error is introduced to the parameters of the speeds at PA=170 deg. Accessory to this standard uncertainty, solutions with PA=175 deg. (also admitted by the data) exhibit only one pattern speed inside 4 kpc, and we consider this circumstance under the semblance of a radially varying PA.Comment: 14 pages in emulateapj format, 12 figures, accepted for publication in Ap

Does the Spine Surgeon’s Experience Affect Fracture Classification, Assessment of Stability, and Treatment Plan in Thoracolumbar Injuries?

Study Design: Prospective survey-based study. Objectives: The AO Spine thoracolumbar injury classification has been shown to have good reproducibility among clinicians. However, the influence of spine surgeons’ clinical experience on fracture classification, stability assessment, and decision on management based on this classification has not been studied. Furthermore, the usefulness of varying imaging modalities including radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) in the decision process was also studied. Methods: Forty-one spine surgeons from different regions, acquainted with the AOSpine classification system, were provided with 30 thoracolumbar fractures in a 3-step assessment: first radiographs, followed by CT and MRI. Surgeons classified the fracture, evaluated stability, chose management, and identified reasons for any changes. The surgeons were divided into 2 groups based on years of clinical experience as \u3c10 years (n = 12) and \u3e10 years (n = 29). Results: There were no significant differences between the 2 groups in correctly classifying A1, B2, and C type fractures. Surgeons with less experience hadmore correct diagnosis in classifyingA3 (47.2% vs 38.5%in step 1, 73.6% vs 60.3% in step 2 and 77.8% vs 65.5% in step 3), A4 (16.7% vs 24.1% in step 1, 72.9% vs 57.8% in step 2 and 70.8% vs 56.0%in step3) and B1 injuries (31.9% vs 20.7% in step 1, 41.7% vs 36.8% in step 2 and 38.9% vs 33.9% in step 3). In the assessment of fracture stability and decision on treatment, the less and more experienced surgeons performed equally. The selection of a particular treatment plan varied in all subtypes except in A1 and C type injuries. Conclusion: Surgeons’ experience did not significantly affect overall fracture classification, evaluating stability and planning the treatment. Surgeons with less experience had a higher percentage of correct classification in A3 and A4 injuries. Despite variations between them in classification, the assessment of overall stability and management decisions were similar between the 2 groups. © The Author(s) 2017

Comparative performance of prediction model, non-expert and telediagnosis of common external and middle ear disease using a patient cohort from Cambodia that included one hundred and thirty-eight ears

Efforts to combat the large global burden of ear and hearing disorders are hampered by poor availability of expert diagnosis We report the first study to directly compare prediction model, non-expert and tele-diagnosis of middle and external ear disorders. A prediction model based upon a novel automated otological symptom questionnaire performed poorly, but absence of otorrhoea was found to reliably exclude a diagnosis of chronic suppurative otitis media. Both on-site non-expert and expert tele-diagnosis had high diagnostic specificity, but low sensitivity. Future work could explore how the validity of these diagnostic methods may be improved

In-depth annotation of SNPs arising from resequencing projects using NGS-SNP

Summary: NGS-SNP is a collection of command-line scripts for providing rich annotations for SNPs identified by the sequencing of whole genomes from any organism with reference sequences in Ensembl. Included among the annotations, several of which are not available from any existing SNP annotation tools, are the results of detailed comparisons with orthologous sequences. These comparisons can, for example, identify SNPs that affect conserved residues, or alter residues or genes linked to phenotypes in another species

Variation in pathogenicity among single-oospore isolates of Sclerospora graminicola, the causal organism of downy mildew in pearl millet

Variation in pathogenicity (virulence and aggressiveness) of various single-oospore isolates of Sclerospora graminicola, the causal organism of downy mildew in pearl millet, was studied. Oospore isolates were maintained as sporangial progenies on the susceptible pearl millet genotype 7042-S through asexual generations. Twenty single-oospore isolates obtained from samples of oospore inocula from three locations (the ICRISAT Centre, Coimbatore, and Hisar) in India, were tested for pathogenicity on 7042-S. All the isolates were virulent on 7042-S and they varied considerably, between and within locations, in infection efficiency (11–44% infection). The S. graminicola populations from the ICRISAT Centre and Hisar were significantly more aggressive than those from Coimbatore. Considerable variation was found among the 10 single-oospore isolates from the ICRISAT Centre in infection efficiency and for latent period on a set of resistant and susceptible genotypes. Seven representative isolates, two each from the ICRISAT Centre (ICOS) and Coimbatore (CBOS), and three from Hisar (HSOS), exhibited variation in infection efficiency, sporangial production capacity, and oospore production rating on the susceptible genotypes 7042-S and NHB 3. A pathogenic fitness index (PFI) was calculated for these isolates as the product of the reciprocal of the latent period × percentage infected seedlings × log10 sporangia per cm2 leaf area × oospore production rating. Aggressiveness of these isolates, measured as PFI, varied greatly. CBOS-1 was the least aggressive with a PFI of 8·5 on NHB 3 and 69·6 on 7042-S; the PFI of the other isolates ranged from 81·1 to 370·5. Downy mildew resistance in three of the five known resistant lines (700651, P7-4 and 7042-R) was consistently effective against all 10 ICOS isolates, indicating that the resistance of these three lines is likely to be more stable, at least at the ICRISAT location, than that of the other two resistant lines