Filament Rotation in the California L1482 Cloud Álvarez-Gutiérrez, R. H.; Stutz, A. M.; Law, C. Y. ...
Astrophysical journal/The Astrophysical journal,
02/2021, Letnik:
908, Številka:
1
Journal Article
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Abstract
We analyze the gas mass distribution, the gas kinematics, and the young stellar objects of the California Molecular Cloud L1482 filament. The mean Gaia DR2 YSO distance is
pc. In terms of ...the gas, the line-mass (M/L) profiles are symmetric scale-free power laws consistent with cylindrical geometry. We calculate the gravitational potential and field profiles based on these. Our IRAM 30 m multi-tracer position–velocity diagrams highlight twisting and turning structures. We measure the C
18
O velocity profile perpendicular to the southern filament ridgeline. The profile is regular, confined (projected
r
≲ 0.4 pc), antisymmetric, and, to first order, linear, with a break at
r
∼ 0.25 pc. We use a simple solid-body rotation toy model to interpret it. We show that the centripetal force, compared to gravity, increases toward the break; when the ratio of forces approaches unity, the profile turns over, just before the implied filament breakup. The timescales of the inner (outer) gradients are ∼0.7 (6.0) Myr. The timescales and relative roles of gravity to rotation indicate that the structure is stable, long lived (∼a few times 6 Myr), and undergoing outside-in evolution. This filament has practically no star formation, a perpendicular Planck plane-of-the-sky magnetic field morphology, and 2D “zig-zag” morphology, which together with the rotation profile lead to the suggestion that the 3D shape is a “corkscrew” filament. These results, together with results in other regions, suggest evolution toward higher densities as rotating filaments shed angular momentum. Thus, magnetic fields may be an essential feature of high-mass (
M
∼ 10
5
M
⊙
) cloud filament evolution toward cluster formation.
ABSTRACT
Infrared dark clouds (IRDCs) are potential hosts of the elusive early phases of high mass star formation (HMSF). Here, we conduct an in-depth analysis of the fragmentation properties of a ...sample of 10 IRDCs, which have been highlighted as some of the best candidates to study HMSF within the Milky Way. To do so, we have obtained a set of large mosaics covering these IRDCs with Atacama Large Millimeter/submillimeter Array (ALMA) at Band 3 (or 3 mm). These observations have a high angular resolution (∼3 arcsec; ∼0.05 pc), and high continuum and spectral line sensitivity (∼0.15 mJy beam−1 and ∼0.2 K per 0.1 km s−1 channel at the N2H+ (1 − 0) transition). From the dust continuum emission, we identify 96 cores ranging from low to high mass (M = 3.4−50.9 M⊙) that are gravitationally bound (αvir = 0.3−1.3) and which would require magnetic field strengths of B = 0.3−1.0 mG to be in virial equilibrium. We combine these results with a homogenized catalogue of literature cores to recover the hierarchical structure within these clouds over four orders of magnitude in spatial scale (0.01–10 pc). Using supplementary observations at an even higher angular resolution, we find that the smallest fragments (<0.02 pc) within this hierarchy do not currently have the mass and/or the density required to form high-mass stars. None the less, the new ALMA observations presented in this paper have facilitated the identification of 19 (6 quiescent and 13 star-forming) cores that retain >16 M⊙ without further fragmentation. These high-mass cores contain trans-sonic non-thermal motions, are kinematically sub-virial, and require moderate magnetic field strengths for support against collapse. The identification of these potential sites of HMSF represents a key step in allowing us to test the predictions from high-mass star and cluster formation theories.
Background:
Little is known of the clinical outcome of patients with older-onset inflammatory bowel disease IBD. We performed a systematic review to determine phenotype and outcomes of older-onset ...IBD compared with younger-onset subjects.
Methods:
A systematic search of Embase and Medline up to June 2015 identified studies investigating phenotype and outcomes of older-onset diagnosed at age ≥ 50 years Crohn’s disease CD and ulcerative colitis UC subjects. Pooled analyses of disease phenotype, medication use, and disease-related surgery were calculated.
Results:
We analysed findings from 43 studies comprising 8274 older-onset and 34641 younger-onset IBD subjects. Compared with younger-onset patients, older-onset CD patients were more likely to have colonic disease (odds ratio OR 2.56, 95% confidence interval CI 1.88 – 3.48) and inflammatory behaviour OR 1.19, 95% CI 1.07 – 1.33, and less likely to have penetrating disease or perianal involvement. More older-onset UC patients had left-sided colitis OR 1.49, 95% CI 1.18 – 1.88. Although fewer older-onset IBD patients received immunomodulators CD: OR 0.44; UC: OR 0.60 or biologicals CD: OR 0.34; UC: OR 0.41, older-onset CD was similar in the need for surgery OR 0.70, 95% CI 0.40 – 1.22 whereas more older-onset UC patients underwent surgery OR 1.36, 95% CI 1.18 – 1.57.
Conclusions:
Elderly IBD patients present with less complicated disease, but have similar or higher rates of surgery than non-elderly patients. Whether this reflects a non-benign disease course, physicians’ reluctance to employ immunomodulators, or both, merits further study which is essential for improving the care of IBD in the elderly.
Summary Elevated levels of circulating cell-free Epstein–Barr virus (EBV) DNA have been detected in plasma and serum samples from nasopharyngeal cancer (NPC) patients by quantitative real time PCR ...(qPCR) test. This qPCR test for circulating EBV DNA was found to be useful in the clinical management of NPC patients. For instance, EBV DNA qPCR test has good sensitivity and specificity in the detection of NPC at disease onset. Increase of the viral DNA load was found in NPC patients at late stages of disease. High EBV DNA load at disease onset or detectable viral load post-treatment was associated with poor survival or frequent relapse in NPC patients. Residual EBV DNA load after primary treatment could be a useful indicator to justify adjuvant chemotherapy. The qPCR test might also be applied to define a poor prognostic group in patients at early stage (I/II) for implementing concurrent chemo-radiotherapy (chemo-RT) to improve patients’ outcome. The test is also useful to monitor distant metastases or response to radiotherapy, chemo-RT or surgery. Supplementary tests, however, are needed to pick up EBV negative WHO type I NPC and test improvement is needed to increase sensitivity in detecting stage I disease and local recurrence.
In the vast Low Nutrient Low‐Chlorophyll (LNLC) Ocean, the vertical nutrient supply from the subsurface to the sunlit surface waters is low, and atmospheric contribution of nutrients may be one order ...of magnitude greater over short timescales. The short turnover time of atmospheric Fe and N supply (<1 month for nitrate) further supports deposition being an important source of nutrients in LNLC regions. Yet, the extent to which atmospheric inputs are impacting biological activity and modifying the carbon balance in oligotrophic environments has not been constrained. Here, we quantify and compare the biogeochemical impacts of atmospheric deposition in LNLC regions using both a compilation of experimental data and model outputs. A metadata‐analysis of recently conducted field and laboratory bioassay experiments reveals complex responses, and the overall impact is not a simple “fertilization effect of increasing phytoplankton biomass” as observed in HNLC regions. Although phytoplankton growth may be enhanced, increases in bacterial activity and respiration result in weakening of biological carbon sequestration. The application of models using climatological or time‐averaged non‐synoptic deposition rates produced responses that were generally much lower than observed in the bioassay experiments. We demonstrate that experimental data and model outputs show better agreement on short timescale (days to weeks) when strong synoptic pulse of aerosols deposition, similar in magnitude to those observed in the field and introduced in bioassay experiments, is superimposed over the mean atmospheric deposition fields. These results suggest that atmospheric impacts in LNLC regions have been underestimated by models, at least at daily to weekly timescales, as they typically overlook large synoptic variations in atmospheric deposition and associated nutrient and particle inputs. Inclusion of the large synoptic variability of atmospheric input, and improved representation and parameterization of key processes that respond to atmospheric deposition, is required to better constrain impacts in ocean biogeochemical models. This is critical for understanding and prediction of current and future functioning of LNLC regions and their contribution to the global carbon cycle.
Key Points
Episodic nature of atmospheric deposition matters in LNLC productivityAtmospheric impact in LNLC area is not a simple “fertilization effect”Atmosphere supplies most of new N & Fe to the mixed layer in some LNLC regions
China has experienced considerable economic losses from a severe deterioration in air quality. To solve this, a comprehensive understanding of the impacts and sources of air pollution is necessary. ...This study aimed to quantify the environmental and human health impacts of PM2.5 and O3 pollution from the six major emission-producing sectors in China. We utilized a chemical transport model to simulate the air quality impacts engendered by sectoral emissions. The consequent impacts on public health and crop production, as well as the corresponding collateral economic costs, were quantified by concentration-response functions. The results show that the sectoral emissions in 2010 caused approximately 1 143 000 (95% confidence interval (CI): 168 000-1 796 000) premature mortalities and a 20 035 (95% CI: 6776-32 166) Gg crop production loss. Of the six sectors, the industrial sector was the largest contributor of air pollution, accounting for 36% of the total impact on health, as well as 41% of crop production loss due to O3 exposure. The impacts attributable to sectoral emissions in China were estimated to cost ∼267 (95% CI: 180-360) billion yuan (0.66% of the annual GDP). Our findings suggest an urgent need to reduce anthropogenic emissions in China, particularly those of the industrial sector. The varying characteristics of impact due to emissions of various sectors highlight the importance of evaluating cobenefits when formulating emission control policies.
We investigated cerebral structural connectivity and its relationship to symptoms in never-medicated individuals with first-onset schizophrenia using diffusion tensor imaging (DTI).
We recruited ...subjects with first episode DSM-IV schizophrenia who had never been exposed to antipsychotic medication (n=34) and age-matched healthy volunteers (n=32). All subjects received DTI and structural magnetic resonance imaging scans. Patients' symptoms were assessed on the Positive and Negative Syndrome Scale. Voxel-based analysis was performed to investigate brain regions where fractional anisotropy (FA) values significantly correlated with symptom scores.
In patients with first-episode schizophrenia, positive symptoms correlated positively with FA scores in white matter associated with the right frontal lobe, left anterior cingulate gyrus, left superior temporal gyrus, right middle temporal gyrus, right middle cingulate gyrus, and left cuneus. Importantly, FA in each of these regions was lower in patients than controls, but patients with more positive symptoms had FA values closer to controls. We found no significant correlations between FA and negative symptoms.
The newly-diagnosed, neuroleptic-naive patients had lower FA scores in the brain compared with controls. There was positive correlation between FA scores and positive symptoms scores in frontotemporal tracts, including left fronto-occipital fasciculus and left inferior longitudinal fasciculus. This implies that white matter dysintegrity is already present in the pre-treatment phase and that FA is likely to decrease after clinical treatment or symptom remission.
We present optical, near-infrared, and mid-infrared imaging of the host galaxy of FRB 121102 with the Gemini North telescope, the Hubble Space Telescope, and the Spitzer Space Telescope. The FRB ...121102 host galaxy is resolved, revealing a bright star-forming region located in the outskirts of the irregular, low-metallicity dwarf galaxy. The star-forming region has a half-light radius of 0.68 kpc ( ), encompassing the projected location of the compact ( pc), persistent radio source that is associated with FRB 121102. The half-light diameter of the dwarf galaxy is 5-7 kpc, and broadband spectral energy distribution fitting indicates that it has a total stellar mass of . The properties of the host galaxy of FRB 121102 are comparable to those of extreme emission line galaxies, also known as hosts to some hydrogen-poor superluminous supernovae and long-duration γ-ray bursts. The projected location of FRB 121102 within the star-forming region supports the proposed connection of FRBs with newly born neutron stars or magnetars.
Summary
Background
Clostridium difficile infection (CDI) is associated with increased mortality in inflammatory bowel disease (IBD), but the risk of colectomy is variable and has not been adequately ...studied.
Aim
To perform a systematic review and meta‐analysis to assess the impact of CDI on colectomy risk in IBD.
Methods
Multiple databases were searched systematically for observational studies reporting colectomy risk in IBD, stratified by the presence of CDI, and the duration of follow‐up (short term 3 months, and long term at least 1 year). Weighted summary estimates were calculated using generalised inverse variance with random‐effects model. Study quality was assessed using the Newcastle–Ottawa scale.
Results
Twelve observational studies were identified and included 35 057 IBD patients with CDI, and 929 259 without CDI. CDI did not increase the short‐term colectomy risk in IBD patients overall (10 studies) (OR: 1.35; 95% CI: 0.68–2.67), or in patients with ulcerative colitis (nine studies) (OR: 1.20; 95% CI: 0.39–3.76). In contrast, CDI was associated with higher long‐term colectomy risk in patients with IBD overall (five studies) (OR: 2.23; 95% CI: 1.18–4.21), and in patients with ulcerative colitis (four studies) (OR: 2.96; 95% CI: 1.19–7.34). The results were stable in subgroups stratified by recruitment period, hospitalisation status and geographical location. All studies were at least of moderate quality. The results were limited in the ability to compare IBD severity and the type of anti‐microbial therapy.
Conclusion
Based on 12 observational studies with at least moderate quality, Clostridium difficile infection appears to increase colectomy risk in IBD in the long‐ but not short‐ term.
Linked ContentThis article is linked to Nelson and Tsai paper. To view this article visit https://doi.org/10.1111/apt.14039.
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