Context.
The Orion Molecular Cloud is the nearest massive-star forming region. Massive stars have profound effects on their environment due to their strong radiation fields and stellar winds. Stellar ...feedback is one of the most crucial cosmological parameters that determine the properties and evolution of the interstellar medium in galaxies.
Aims.
We aim to understand the role that feedback by stellar winds and radiation play in the evolution of the interstellar medium. Velocity-resolved observations of the C
II
158
μ
m fine-structure line allow us to study the kinematics of UV-illuminated gas. Here, we present a square-degree-sized map of C
II
emission from the Orion Nebula complex at a spatial resolution of 16′′ and high spectral resolution of 0.2 km s
−1
, covering the entire Orion Nebula (M 42) plus M 43 and the nebulae NGC 1973, 1975, and 1977 to the north. We compare the stellar characteristics of these three regions with the kinematics of the expanding bubbles surrounding them.
Methods.
We use C
II
158
μ
m line observations over an area of 1.2 deg
2
in the Orion Nebula complex obtained by the upGREAT instrument onboard SOFIA.
Results.
The bubble blown by the O7V star
θ
1
Ori C in the Orion Nebula expands rapidly, at 13 km s
−1
. Simple analytical models reproduce the characteristics of the hot interior gas and the neutral shell of this wind-blown bubble and give us an estimate of the expansion time of 0.2 Myr. M 43 with the B0.5V star NU Ori also exhibits an expanding bubble structure, with an expansion velocity of 6 km s
−1
. Comparison with analytical models for the pressure-driven expansion of H
II
regions gives an age estimate of 0.02 Myr. The bubble surrounding NGC 1973, 1975, and 1977 with the central B1V star 42 Orionis expands at 1.5 km s
−1
, likely due to the over-pressurized ionized gas as in the case of M 43. We derive an age of 0.4 Myr for this structure.
Conclusions.
We conclude that the bubble of the Orion Nebula is driven by the mechanical energy input by the strong stellar wind from
θ
1
Ori C, while the bubbles associated with M 43 and NGC 1977 are caused by the thermal expansion of the gas ionized by their central later-type massive stars.
Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest ...carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.
Context. L1630 in the Orion B molecular cloud, which includes the iconic Horsehead Nebula, illuminated by the star system σ Ori, is an example of a photodissociation region (PDR). In PDRs, stellar ...radiation impinges on the surface of dense material, often a molecular cloud, thereby inducing a complex network of chemical reactions and physical processes. Aims. Observations toward L1630 allow us to study the interplay between stellar radiation and a molecular cloud under relatively benign conditions, that is, intermediate densities and an intermediate UV radiation field. Contrary to the well-studied Orion Molecular Cloud 1 (OMC1), which hosts much harsher conditions, L1630 has little star formation. Our goal is to relate the C ii fine-structure line emission to the physical conditions predominant in L1630 and compare it to studies of OMC1. Methods. The C ii 158 μm line emission of L1630 around the Horsehead Nebula, an area of 12′ × 17′, was observed using the upgraded German Receiver for Astronomy at Terahertz Frequencies (upGREAT) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). Results. Of the C ii emission from the mapped area 95%, 13 L⊙, originates from the molecular cloud; the adjacent H ii region contributes only 5%, that is, 1 L⊙. From comparison with other data (CO (1 − 0)-line emission, far-infrared (FIR) continuum studies, emission from polycyclic aromatic hydrocarbons (PAHs)), we infer a gas density of the molecular cloud of nH ~ 3 × 103 cm-3, with surface layers, including the Horsehead Nebula, having a density of up to nH ~ 4 × 104 cm-3. The temperature of the surface gas is T ~ 100 K. The average C ii cooling efficiency within the molecular cloud is 1.3 × 10-2. The fraction of the mass of the molecular cloud within the studied area that is traced by C ii is only 8%. Our PDR models are able to reproduce the FIR-C ii correlations and also the CO (1 − 0)-C ii correlations. Finally, we compare our results on the heating efficiency of the gas with theoretical studies of photoelectric heating by PAHs, clusters of PAHs, and very small grains, and find the heating efficiency to be lower than theoretically predicted, a continuation of the trend set by other observations. Conclusions. In L1630 only a small fraction of the gas mass is traced by C ii. Most of the C ii emission in the mapped area stems from PDR surfaces. The layered edge-on structure of the molecular cloud and limitations in spatial resolution put constraints on our ability to relate different tracers to each other and to the physical conditions. From our study, we conclude that the relation between C ii emission and physical conditions is likely to be more complicated than often assumed. The theoretical heating efficiency is higher than the one we calculate from the observed C ii emission in the L1630 molecular cloud.
The preferred type of post-remission therapy (PRT) in patients with acute myeloid leukemia (AML) in first complete remission (CR1) is a subject of continued debate, especially in patients at higher ...risk of nonrelapse mortality (NRM), including patients >40 years of age. We report results of a time-dependent multivariable analysis of allogenic hematopoietic stem cell transplantation (alloHSCT) (n=337) versus chemotherapy (n=271) or autologous HSCT (autoHSCT) (n=152) in 760 patients aged 40-60 years with AML in CR1. Patients receiving alloHSCT showed improved overall survival (OS) as compared with chemotherapy (respectively, 57±3% vs 40±3% at 5 years, P<0.001). Comparable OS was observed following alloHSCT and autoHSCT in patients with intermediate-risk AML (60±4 vs 54±5%). However, alloHSCT was associated with less relapse (hazard ratio (HR) 0.51, P<0.001) and better relapse-free survival (RFS) (HR 0.74, P=0.029) as compared with autoHSCT in intermediate-risk AMLs. AlloHSCT was applied following myeloablative conditioning (n=157) or reduced intensity conditioning (n=180), resulting in less NRM, but comparable outcome with respect to OS, RFS and relapse. Collectively, these results show that alloHSCT is to be preferred over chemotherapy as PRT in patients with intermediate- and poor-risk AML aged 40-60 years, whereas autoHSCT remains a treatment option to be considered in patients with intermediate-risk AML.
Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity ...within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain: BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. Software format:.csv and.SQL.
Post-remission treatment (PRT) in patients with cytogenetically normal (CN) acute myeloid leukemia (AML) in first complete remission (CR1) is debated. We studied 521 patients with CN-AML in CR1, for ...whom mutational status of NPM1 and FLT3-ITD was available, including the FLT3-ITD allelic ratio. PRT consisted of reduced intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (alloHSCT) (n=68), myeloablative conditioning (MAC) alloHSCT (n=137), autologous hematopoietic stem cell transplantation (autoHSCT) (n=168) or chemotherapy (n=148). Favorable overall survival (OS) was found for patients with mutated NPM1 without FLT3-ITD (71±4%). Outcome in patients with a high FLT3-ITD allelic ratio appeared to be very poor with OS and relapse-free survival (RFS) of 23±8% and 12±6%, respectively. Patients with wild-type NPM1 without FLT3-ITD or with a low allelic burden of FLT3-ITD were considered as intermediate-risk group because of similar OS and RFS at 5 years, in which PRT by RIC alloHSCT resulted in better OS and RFS as compared with chemotherapy (hazard ratio (HR) 0.56, P=0.022 and HR 0.50, P=0.004, respectively) or autoHSCT (HR 0.60, P=0.046 and HR 0.60, P=0.043, respectively). The lowest cumulative incidence of relapse (23±4%) was observed following MAC alloHSCT. These results suggest that alloHSCT may be preferred in patients with molecularly intermediate-risk CN-AML, while the choice of conditioning type may be personalized according to risk for non-relapse mortality.
Context.
The CII 158 μm far-infrared fine-structure line is one of the dominant cooling lines of the star-forming interstellar medium. Hence CII emission originates in and thus can be used to trace a ...range of ISM processes. Velocity-resolved large-scale mapping of CII in star-forming regions provides a unique perspective of the kinematics of these regions and their interactions with the exciting source of radiation.
Aims.
We explore the scientific applications of large-scale mapping of velocity-resolved CII observations. With the CII observations, we investigate the effect of stellar feedback on the ISM. We present the details of observation, calibration, and data reduction using a heterodyne array receiver mounted on an airborne observatory.
Methods.
A 1.15 square degree velocity-resolved map of the Orion molecular cloud centred on the bar region was observed using the German REceiver for Astronomy at Terahertz Frequencies (upGREAT) heterodyne receiver flying on board the Stratospheric Observatory for Infrared Astronomy. The data were acquired using the 14 pixels of the German REceiver for Astronomy at Terahertz Frequencies that were observed in an on-the-fly mapping mode. 2.4 million spectra were taken in total. These spectra were gridded into a three-dimensional cube with a spatial resolution of 14.1 arcseconds and a spectral resolution of 0.3 km s
−1
.
Results.
A square-degree CII map with a spectral resolution of 0.3 km s
−1
is presented. The scientific potential of this data is summarized with discussion of mechanical and radiative stellar feedback, filament tracing using CII, CII opacity effects, CII and carbon recombination lines, and CII interaction with the large molecular cloud. The data quality and calibration is discussed in detail, and new techniques are presented to mitigate the effects of unavoidable instrument deficiencies (e.g. baseline stability) and thus to improve the data quality. A comparison with a smaller CII map taken with the
Herschel
/Heterodyne Instrument for the Far-Infrared spectrometer is presented.
Conclusions.
Large-scale CII mapping provides new insight into the kinematics of the ISM. The interaction between massive stars and the ISM is probed through CII observations. Spectrally resolving the CII emission is necessary to probe the microphysics induced by the feedback of massive stars. We show that certain heterodyne instrument data quality issues can be resolved using a spline-based technique, and better data correction routines allow for more efficient observing strategies.
Among patients with acute myeloid leukemia, gene sequencing during remission revealed that persistent mutations in genes associated with clonal hematopoiesis did not have value for predicting relapse ...but that persistent mutations in other leukemia-associated genes had such value.
The gut mounts secretory immunoglobulin A (SIgA) responses to commensal bacteria through nonredundant T cell-dependent (TD) and T cell-independent (TI) pathways that promote the establishment of ...mutualistic host-microbiota interactions. SIgAs from the TD pathway target penetrant bacteria, and their induction requires engagement of CD40 on B cells by CD40 ligand on T follicular helper cells. In contrast, SIgAs from the TI pathway bind a larger spectrum of bacteria, but the mechanism underpinning their production remains elusive. Here, we show that the intestinal TI pathway required CD40-independent B cell-activating signals from TACI, a receptor for the innate CD40 ligand-like factors BAFF and APRIL. TACI-induced SIgA responses targeted a fraction of the gut microbiota without shaping its overall composition. Of note, TACI was dispensable for TD induction of IgA in gut-associated lymphoid organs. Thus, BAFF/APRIL signals acting on TACI orchestrate commensal bacteria-specific SIgA responses through an intestinal TI program.
PDF
