Lung cancer is the leading cause of cancer death worldwide. The absence of symptoms in early-stage (I/II) disease, when curative treatment is possible, results in >70% of cases being diagnosed at ...late stage (III/IV), when treatment is rarely curative. This contributes greatly to the poor prognosis of lung cancer, which sees only 16.2% of individuals diagnosed with the disease alive at 5 years. Early detection is key to improving lung cancer survival outcomes. As a result, there has been longstanding interest in finding a reliable screening test. After little success with chest radiography and sputum cytology, in 2011 the United States National Lung Screening Trial demonstrated that annual low-dose computed tomography (LDCT) screening reduced lung cancer-specific mortality by 20%, when compared with annual chest radiography. In 2020, the NELSON study demonstrated an even greater reduction in lung cancer-specific mortality for LDCT screening at 0, 1, 3 and 5.5 years of 24% in men, when compared to no screening. Despite these impressive results, a call to arms in the 2017 European position statement on lung cancer screening (LCS) and the widespread introduction across the United States, there was, until recently, no population-based European national screening programme in place. We address the potential barriers and outstanding concerns including common screening foes, such as false-positive tests, overdiagnosis and the negative psychological impact of screening, as well as others more unique to LDCT LCS, including appropriate risk stratification of potential participants, radiation exposure and incidental findings. In doing this, we conclude that whilst the evidence generated from ongoing work can be used to refine the screening process, for those risks which remain, appropriate and acceptable mitigations are available, and none should serve as barriers to the implementation of national unified LCS programmes across Europe and beyond.
•LCS with LDCT in high-risk individuals reduces lung cancer mortality.•LCS has been introduced in the United States, but few unified, national LCS programmes are in place across Europe.•Barriers to the widespread implementation of LCS in Europe are well documented with appropriate mitigations available.•Necessary research is underway across several European counties to address existing barriers and optimise practice.•Existing barriers should not serve as reasons not to implement national, unified LCS programmes across Europe.
We present a comparison of Submillimetre Common User Bolometer Array-2 (SCUBA-2) 850-μm and Herschel 70–500-μm observations of the L1495 filament in the Taurus Molecular Cloud with the goal of ...characterizing the SCUBA-2 Gould Belt Survey (GBS) data set. We identify and characterize starless cores in three data sets: SCUBA-2 850-μm, Herschel 250-μm, and Herschel 250-μm spatially filtered to mimic the SCUBA-2 data. SCUBA-2 detects only the highest-surface-brightness sources, principally detecting protostellar sources and starless cores embedded in filaments, while Herschel is sensitive to most of the cloud structure, including extended low-surface-brightness emission. Herschel detects considerably more sources than SCUBA-2 even after spatial filtering. We investigate which properties of a starless core detected by Herschel determine its detectability by SCUBA-2, and find that they are the core's temperature and column density (for given dust properties). For similar-temperature cores, such as those seen in L1495, the surface brightnesses of the cores are determined by their column densities, with the highest-column-density cores being detected by SCUBA-2. For roughly spherical geometries, column density corresponds to volume density, and so SCUBA-2 selects the densest cores from a population at a given temperature. This selection effect, which we quantify as a function of distance, makes SCUBA-2 ideal for identifying those cores in Herschel catalogues that are closest to forming stars. Our results can now be used by anyone wishing to use the SCUBA-2 GBS data set.
ABSTRACT The James Clerk Maxwell Telescope Gould Belt Legacy Survey obtained SCUBA-2 observations of dense cores within three sub-regions of Orion B: LDN 1622, NGC 2023/2024, and NGC 2068/2071, all ...of which contain clusters of cores. We present an analysis of the clustering properties of these cores, including the two-point correlation function and Cartwright's Q parameter. We identify individual clusters of dense cores across all three regions using a minimal spanning tree technique, and find that in each cluster, the most massive cores tend to be centrally located. We also apply the independent M- technique and find a strong correlation between core mass and the local surface density of cores. These two lines of evidence jointly suggest that some amount of mass segregation in clusters has happened already at the dense core stage.
We employ SCUBA-2 (Submillimetre Common-User Bolometer Array 2) observations of the Orion A North molecular cloud to derive column density and temperature maps. We apply a novel, Hessian-based ...structural identification algorithm for detection of prestellar cores to these data, allowing for automated generation of the prestellar mass function. The resulting mass function is observed to peak at
$1.39^{+0.18}_{-0.19}$
M⊙, indicating a star-forming efficiency lower limit of ∼14 per cent when compared with the Orion nebula Cluster initial mass function (IMF) peak. Additionally, the prestellar mass function is observed to decay with a high-mass power-law exponent
$\alpha =2.53^{+0.16}_{-0.14}$
, indicating approximate functional similarity with the Salpeter IMF (α = 2.35). This result, when combined with the results of previous investigations suggests a regional dependence of the star-forming efficiency.
Context. The physical origin behind organic emission lines in embedded low-mass star formation has been fiercely debated over the last two decades. A multitude of scenarios have been proposed, from a ...hot corino to PDRs on cavity walls to shock excitation. Aims. The aim of this paper is to determine the location and the corresponding physical conditions of the gas responsible for organics emission lines. The outflows around the small protocluster NGC 2071 are an ideal testbed that can be used to differentiate between various scenarios. Methods. Using Herschel-HIFI and the Submillimeter Array, observations of CH3OH, H2CO, and CH3CN emission lines over a wide range of excitation energies were obtained. Comparisons to a grid of radiative transfer models provide constraints on the physical conditions. Comparison to H2O line shape is able to trace gas-phase synthesis versus a sputtered origin. Results. Emission of organics originates in three separate spots: the continuum sources IRS 1 (“B”) and IRS 3 (“A”) and a new outflow position (“F”). Densities are above 107 cm-3 and temperatures between 100 K and 200 K. CH3OH emission observed with HIFI originates in all three regions and cannot be associated with a single region. Very little organic emission originates outside of these regions. Conclusions. Although the three regions are small (<1500 AU), gas-phase organics likely originate from sputtering of ices as a result of outflow activity. The derived high densities (>107 cm-3) are likely a requirement for organic molecules to survive from being immediately destroyed by shock products after evaporation. The lack of spatially extended emission confirms that organic molecules cannot (re-)form through gas-phase synthesis, as opposed to H2O, which shows strong line wing emission. The lack of CH3CN emission at “F” is evidence for a different history of ice processing because of the absence of a protostar at that location and recent ice mantle evaporation.
Context. NGC 7129 FIRS 2 is a young intermediate-mass (IM) protostar, which is associated with two energetic bipolar outflows and displays clear signs of the presence of a hot core. It has been ...extensively observed with ground based telescopes and within the WISH guaranteed time Herschel key program. Aims. This paper is dedicated to the modeling of the C18O and HDO lines in NGC 7129 FIRS 2. Our goal is to investigate the chemistry in the envelope and hot core of this IM protostar. Methods. We present new observations of the C18O 3 → 2 and the HDO 312 → 221 lines towards NGC 7129 FIRS 2. Combining these observations with Herschel data and modeling their emissions, we constrain the C18O and HDO abundance profiles across the protostellar envelope. In particular, we derive the abundance of C18O and HDO in the hot core. Results. The intensities of the C18O lines are well reproduced assuming that the C18O abundance decreases through the protostellar envelope from the outer edge towards the centre until the point where the gas and dust reach the CO evaporation temperature (≈20–25 K) where the C18O is released back to the gas phase. Once the C18O is released to the gas phase, the modelled C18O abundance is found to be ≈ 1.6 × 10-8, which is a factor of 10 lower than the reference abundance. This result is supported by the non-detection of C18O 9 → 8, which proves that even in the hot core (Tk > 100 K) the CO abundance must be 10 times lower than the reference value. Several scenarios are discussed to explain this C18O deficiency. One possible explanation is that during the pre-stellar and protostellar phase, the CO is removed from the grain mantles by reactions to form more complex molecules. Our HDO modeling shows that the emission of HDO 312 → 221 line is maser and comes from the hot core (Tk > 100 K). Assuming the physical structure derived by Crimier et al. (2010), we determine a HDO abundance of ~0.4−1 × 10-7 in the hot core of this IM protostar. Conclusions.Herschel data combined with ground based observations have allowed us to estimate the C18O and HDO abundance in the protostellar envelope and hot core of an IM protostar. The HDO abundance in the hot core is ~0.4−1 × 10-7, similar to that found in the hot corinos NGC 1333 IRAS 2A and IRAS 16293−2422. The C18O abundance, at ≈ 1.6 × 10-8, is a factor of 10 lower than the reference value.
In this paper, we present the first observations of the Ophiuchus molecular cloud performed as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) with the SCUBA-2 instrument. We ...demonstrate methods for combining these data with previous HARP CO, Herschel, and IRAM N2H+ observations in order to accurately quantify the properties of the SCUBA-2 sources in Ophiuchus. We produce a catalogue of all of the sources found by SCUBA-2. We separate these into protostars and starless cores. We list all of the starless cores and perform a full virial analysis, including external pressure. This is the first time that external pressure has been included in this level of detail. We find that the majority of our cores are either bound or virialized. Gravitational energy and external pressure are on average of a similar order of magnitude, but with some variation from region to region. We find that cores in the Oph A region are gravitationally bound prestellar cores, while cores in the Oph C and E regions are pressure-confined. We determine that N2H+ is a good tracer of the bound material of prestellar cores, although we find some evidence for N2H+ freeze-out at the very highest core densities. We find that non-thermal linewidths decrease substantially between the gas traced by C18O and that traced by N2H+, indicating the dissipation of turbulence at higher densities. We find that the critical Bonnor–Ebert stability criterion is not a good indicator of the boundedness of our cores. We detect the pre-brown dwarf candidate Oph B-11 and find a flux density and mass consistent with previous work. We discuss regional variations in the nature of the cores and find further support for our previous hypothesis of a global evolutionary gradient across the cloud from south-west to north-east, indicating sequential star formation across the region.
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