Mass Doubling Time Research Articles

The effect of mass and morphology on the mass assembly of galaxies

The pace at which galaxies grew into their current stellar masses and how this growth is regulated is still not fully understood, nor is the role that morphology plays in this process. We applied full spectral fitting techniques with pyPipe3D to the MaNGA sample to obtain its star formation and stellar mass histories and used these to investigate the mass assembly of galaxies by measuring how their specific star formation correlates to their stellar mass at different look-back times. We find that the correlation between these two parameters was shallower in the past. Galaxies used to have similar mass doubling times and the current negative correlation between the specific star formation and M* is primarily due to more massive galaxies ‘dropping’ off the main sequence earlier than less massive ones. Additionally, selecting the galaxies into bins based on their present-day morphology shows a segregation in specific star formation rate (sSFR) that is maintained even at high look-back times, showing that the factors that determine which morphology a galaxy ends up in are in place at very early times. Similarly, selecting them based on their current star formation status shows that, on average, currently retired galaxies used to have slightly a higher sSFR before the drop-off, whereas galaxies that have continued to form stars until today had a lower sSFR initially. We compare our results to a set of cosmic surveys, finding partial agreement in our results with several of them, though with significant offsets in redshift. Finally, we discuss how our results fit with certain theoretical models on galaxy evolution as well as cosmological simulations.

Computed tomography radiomics study of invasion and instability of lung adenocarcinoma manifesting as ground glass nodule.

Ground-glass nodule (GGN) is the most common manifestation of lung adenocarcinoma on computed tomography (CT). Clinically, the success rate of preoperative diagnosis of GGN by puncture biopsy and other means is still low. The aim of this study is to investigate the clinical and radiomics characteristics of lung adenocarcinoma presenting as GGN on CT images using radiomics analysis methods, establish a radiomics model, and predict the classification of pathological tissue and instability of GGN type lung adenocarcinoma. This study retrospectively collected 249 patients with 298 GGN lesions who were pathologically confirmed of having lung adenocarcinoma. The images were imported into the Siemens scientific research prototype software to outline the region of interest and extract the radiomics features. Logistic model A (a radiomics model to identify the infiltration of lung adenocarcinoma manifesting as GGNs) was established using features after the dimensionality reduction process. The receiver operating characteristic (ROC) curve of the model on training set and the verification set was drawn, and the area under the curve (AUC) was calculated. Second, a total of 112 lesions were selected from 298 lesions originating from CT images of at least two occasions, and the time between the first CT and the preoperative CT was defined as not less than 90 days. The mass doubling time (MDT) of all lesions was calculated. According to the different MDT diagnostic thresholds instability was predicted. Finally, their AUCs were calculated and compared. There were statistically significant differences in age and lesion location distribution between the "noninvasive" lesion group and the invasive lesion group (P<0.05), but there were no statistically significant differences in sex (P>0.05). Model A had an AUC of 0.89, sensitivity of 0.75, and specificity of 0.86 in the training set and an AUC of 0.87, sensitivity of 0.63, and specificity of 0.90 in the validation set. There was no significant difference statistically in MDT between "noninvasive" lesions and invasive lesions (P>0.05). The AUCs of radiomics models B1, B2 and B3 were 0.89, 0.80, and 0.81, respectively; the sensitivities were 0.71, 0.54, and 0.76, respectively; the specificities were 0.83, 0.77, and 0.60, respectively; and the accuracies were 0.78, 0.65, and 0.69, respectively. There were statistically significant differences in age and location of lesions between the "noninvasive" lesion group and the invasive lesion group. The radiomics model can predict the invasiveness of lung adenocarcinoma manifesting as GGNs. There was no significant difference in MDT between "noninvasive" lesions and invasive lesions. The radiomics model can predict the instability of lung adenocarcinoma manifesting as GGN. When the threshold of MDT was set at 813 days, the model had higher specificity, accuracy, and diagnostic efficiency.

Growth characteristics of early-stage (IA) lung adenocarcinoma and its value in predicting lymph node metastasis

BackgroundWe aim to compare the differences in growth characteristics between part-solid and solid lung adenocarcinoma, and to investigate the value of volume doubling time (VDT) or mass doubling time (MDT) in predicting lymph node (LN) metastasis and preoperative evaluation in patients of early-stage (IA) non-small cell lung cancer (NSCLC).MethodWe reviewed 8,653 cases of surgically resected stage IA lung adenocarcinoma between 2018 and 2022, with two follow-up visits at least 3 months apart, comparing diameter, volume, and mass growth of pSN and SN. VDT and MDT calculations for nodules with a volume change of at least 25%. Univariable or multivariable analysis was used to identify the risk factors. The area under the curve (AUC) for the receiver operating characteristic (ROC) curves was used to evaluate the diagnostic value.ResultsA total of 144 patients were included 114 with solid nodules (SN) and 25 with part-solid nodules (pSN). During the follow-up period, the mean VDTt and MDTt of SN were shorter than those of pSN, 337 vs. 541 days (p = 0.005), 298 vs. 458 days (p = 0.018), respectively. Without considering the ground-glass component, the mean VDTc and MDTc of SN were shorter than the solid component of pSN, 337 vs. 498 days (p = 0.004) and 298 vs. 453 days (p = 0.003), respectively. 27 nodules were clinically and pathologically diagnosed as N1/N2. Logistic regression identified initial diameter (p < 0.001), consolidation increase (p = 0.019), volume increase (p = 0.020), mass increase (p = 0.021), VDTt (p = 0.002), and MDTt (p = 0.004) were independent factors for LN metastasis. The ROC curves showed that the AUC for VDTt was 0.860 (95% CI, 0.778–0.943; p < 0.001) and for MDTt was 0.848 (95% CI, 0.759–0.936; p < 0.001).ConclusionsOur study showed significant differences in the growth characteristics of pSN and SN, and the application of VDT and MDT could be a valid predictor LN metastasis in patients with early-stage NSCLC.

Growth Regularity of Pulmonary Ground Glass Nodules Based on 3D Reconstruction Technology

Since the popularization of computed tomography (CT) technology, the detection rate of pulmonary ground glass nodules (GGNs) with imaging follow-up as the main management method has increased significantly. The purpose of this study is to quantitatively analyze the changes of pulmonary GGNs during the follow-up process with three-dimensional reconstruction technology, explore the natural progression of pulmonary GGNs, and provide effective basis for clinical guidance for patients to conduct reasonable management of nodules. A total of 115 cases of pulmonary GGNs with regular follow-up in the Combined Outpatient Department of Zhoushan Hospital from March 2015 to November 2022 were enrolled. Quantitative imaging features of nodules were extracted by semi-automatic segmentation of 3D Slicer software to evaluate the growth of nodules and clinical intervention during follow-up. The average baseline age of the patients was (56.9±10.1) yr. The mean follow-up time was (48.8±18.9) months. The two-dimensional diameter of baseline CT scan was (7.9±2.9) mm, and the maximum three-dimensional diameter was (10.1±3.4) mm. The two-dimensional diameter of the last CT scan was (9.9±4.7) mm, and the maximum three-dimensional diameter was (11.4±5.1) mm. A total of 27 cases (23.5%) showed an increase during follow-up, with a median volume doubling time of 822 days and a median mass doubling time of 1,007 days. 32 cases were surgically resected, including 6 cases of invasive adenocarcinoma (IAC), 16 cases of minimally invasive adenocarcinoma (MIA), 8 cases of adenocarcinoma in situ (AIS) and 2 cases of atypical adenomatous hyperplasia (AAH). Five nodules underwent surgical intervention due to the progression of two-dimensional diameter, which was pathologically confirmed as pre-invasive lesions, but their three-dimensional maximum diameter showed no significant change. Nodular morphology, lobulated sign, spiculated sign and vacuole signs all promoted the growth of nodules in univariate analysis. There were significant differences in age, baseline diameter, mean CT value, median CT value, 10% and 90% percentile CT number between the growth group and the stable group (P<0.05). Multivariate Logistic regression analysis showed that age and average CT value were risk factors for nodule growth (P<0.05). Receiver-operating characteristic (ROC) curve analysis results indicated that the age ≥63 years old, the baseline three-dimensional maximum diameter ≥9.2 mm, and the average CT value ≥-507.8 HU were more likely to accelerate the growth of GGNs. The maximum three-dimensional diameter ≥14.4 mm and the average CT value ≥-495.7 HU may be a higher malignant probability. GGNs show an inert growth process, and the use of three-dimensional measurements during follow-up is of greater significance. For persistent glass grinding nodules ≥63 years old, the baseline three-dimensional maximum diameter ≥9.2 mm, and the average CT value ≥-507.8 HU are more likely to increase. However, most nodules still have good prognosis after progression, and long-term follow-up is safe.

Extending Validity of the Bacterial Cell Cycle Model through Thymine Limitation: A Personal View.

The contemporary view of bacterial physiology was established in 1958 at the "Copenhagen School", culminating a decade later in a detailed description of the cell cycle based on four parameters. This model has been subsequently supported by numerous studies, nicknamed BCD (The Bacterial Cell-Cycle Dogma). It readily explains, quantitatively, the coupling between chromosome replication and cell division, size and DNA content. An important derivative is the number of replication positions n, the ratio between the time C to complete a round of replication and the cell mass doubling time τ; the former is constant at any temperature and the latter is determined by the medium composition. Changes in cell width W are highly correlated to n through the equation for so-called nucleoid complexity NC (=(2n - 1)/(ln2 × n)), the amount of DNA per terC (i.e., chromosome) in genome equivalents. The narrow range of potential n can be dramatically extended using the method of thymine limitation of thymine-requiring mutants, which allows a more rigorous testing of the hypothesis that the nucleoid structure is the primary source of the signal that determines W during cell division. How this putative signal is relayed from the nucleoid to the divisome is still highly enigmatic. The aim of this Opinion article is to suggest the possibility of a new signaling function for nucleoid DNA.

Spatially Resolved Stellar Populations of 0.3 < z < 6.0 Galaxies in WHL 0137–08 and MACS 0647+70 Clusters as Revealed by JWST: How Do Galaxies Grow and Quench over Cosmic Time?

We study the spatially resolved stellar populations of 444 galaxies at 0.3 < z < 6.0 in two clusters (WHL 0137–08 and MACS 0647+70) and a blank field, combining imaging data from the Hubble Space Telescope and JWST to perform spatially resolved spectral energy distribution (SED) modeling using piXedfit. The high spatial resolution of the imaging data combined with magnification from gravitational lensing in the cluster fields allows us to resolve a large fraction of our galaxies (109) to subkiloparsec scales. At redshifts around cosmic noon and higher (2.5 ≲ z ≲ 6.0), we find mass-doubling times to be independent of radius, inferred from flat specific star formation rate (sSFR) radial profiles and similarities between the half-mass and half-SFR radii. At lower redshifts (1.5 ≲ z ≲ 2.5), a significant fraction of our star-forming galaxies shows evidence for nuclear starbursts, inferred from a centrally elevated sSFR and a much smaller half-SFR radius compared to the half-mass radius. At later epochs, we find more galaxies suppress star formation in their centers but are still actively forming stars in the disk. Overall, these trends point toward a picture of inside-out galaxy growth consistent with theoretical models and simulations. We also observe a tight relationship between the central mass surface density and global stellar mass with ∼0.38 dex scatter. Our analysis demonstrates the potential of spatially resolved SED analysis with JWST data. Future analysis with larger samples will be able to further explore the assembly of galaxy mass and the growth of their structures.

Gas accretion onto Jupiter mass planets in discs with laminar accretion flows

Context. Numerous studies have shown that a gap-forming Jovian mass planet embedded in a protoplanetary disc, in which a turbulent viscosity operates, can accrete gas efficiently through the gap, and for typical parameters it doubles its mass in ~0.1 Myr. The planet also migrates inwards on a timescale that is closely related to the local viscous evolution timescale, which is also typically 0.1 Myr. These timescales are short compared to protoplanetary disc lifetimes, and raise questions about the origins of the cold gas giant exoplanets that have been discovered in abundance. It is understood that protoplanetary discs are unlikely to be globally turbulent, and instead they may launch magnetised winds such that accretion towards the star occurs in laminar accretion flows located in narrow layers near the surfaces of the disc. Aims. The aim of this study is to examine the rate at which gas accretes onto Jovian mass planets that are embedded in layered protoplanetary discs, and to compare the results with those obtained for viscous models. Methods. We use 3D hydrodynamical simulations of planets embedded in protoplanetary discs, in which a constant radial mass flux towards the star of ṁ = 10−8 M⊙ yr−1 is sustained. We consider a classical viscous α disc model, and also models in which an external torque is applied in narrow surface layers to mimic the effects of a magnetised wind. The accreting layers have a variety of depths, as parameterised by their column densities ΣA, and we consider values of ΣA in the range 0.1−10 g cm−2. Results. The viscous disc model gives results in agreement with previous studies. In accord with our recent work that examines the migration of Jovian mass planets in layered models, we find the accretion rate onto the planet in the layered models crucially depends on the ability of the planet to block the wind-induced mass flow towards the star. For ΣA = 10 g cm−2, the planet torque can block the mass flow in disc, accretion onto the planet is slow, and a mass doubling time of 10 Myr is obtained. For ΣA = 0.1 g cm−2, the flow is not blocked, accretion is fast, and the mass doubling time is 0.2 Myr. Conclusions. Our results show that although the radial mass flow through the layered disc models is always 10−8 M⊙ yr−1, adopting different values of ΣA leads to very different gas accretion rates onto embedded gas giant planets.

Natural progression of persistent pure ground-glass nodules 10mm or smaller: long-term observation and risk factor assessment.

Semi-automatic segmentation was used to investigate the natural progression of pure ground-glass nodules (pGGNs) of 5-10mm in long-term follow-up and to analyze independent risk factors for subsequent growth. A total of 154 pGGNs of 5-10mm from 132 patients with 698 follow-up CT scans were retrospectively identified. Subsequently, enrolled pGGNs were semiautomatically segmented on initial and follow-up CT to obtain diameter, density and volume, thus calculating mass, volume doubling time (VDT), and mass doubling time (MDT). Kaplan‒Meier analysis and multivariate Cox proportional risk regression were performed to explore independent predictors of pGGN growth. We analyzed growth differences among different pathological results of pGGNs confirmed by surgery. The prognosis was analyzed using the total diameter or solid size of the nodules on the last preoperative CT. Among the 85 (55.2%) pGGNs with growth, 5.9%, 51.8%, and 80.0% showed growth within 1, 3, and 5years, respectively. The median VDT and MDT were 1206.4 (range 349.8-5134.4) days and 1161.3 (range 339.4-6630.4) days, respectively. The multivariate Cox risk regression analysis showed that mean CT attenuation (m-CTA) [hazard ratio (HR) = 2.098, p = 0.010] and roundness index (HR = 1.892, p = 0.021) were independent risk factors for pGGN growth. In total, 67.6% of surgically resected and growing pGGNs were invasive non-mucinous adenocarcinoma (IA), including 2 cases of endpoint events, showing a PSN with solid components of 5.6mm and a solid nodule with a diameter of 19.9mm. pGGNs of 5-10mm showed an indolent clinical course. Follow-up CT imaging of pGGNs in the latter half of the first two years should be a rational management strategy. Small pGGNs with a larger overall m-CTA and roundness index on baseline CT are more likely to grow.

Indeterminate pulmonary subsolid nodules in patients with no history of cancer: growing prediction, CT pattern, and pathological diagnosis.

PURPOSE We aimed to evaluate and compare the growth patterns among pathological types of inde- terminate subsolid nodules in patients without a history of cancer as observed on computed tomography (CT). METHODS This retrospective study included 77 consecutive patients with 80 indeterminate subsolid nod- ules on unenhanced thin-section CT. Subsolid nodules were classified into 2 growth pattern groups based on volume: growth (n = 35) and non-growth (n = 42). According to the pathologi- cal diagnosis, subsolid nodules were further subdivided into 3 groups: adenocarcinoma in situ (growth, n = 8 vs. non-growth, n = 22), minimally invasive adenocarcinoma (n = 14 vs. n = 15), and invasive adenocarcinoma (n=13 vs. n=5). Kaplan-Meier and Cox proportional hazards regres- sion analyses were performed to identify the risk factors for subsolid nodules growth. The CT findings of the 35 subsolid nodules in the growth group were compared among the 3 pathologi- cal groups. RESULTS In the growth group, the overall mean volume doubling time and mass doubling time (MDT) were 811.5 days and 616.5 days, respectively. Patient's age (odds ratio=1.041, P=.045) and CT subtype of non-solid nodule and part-solid nodule (odds ratio=3.430, P=.002) could predict subsolid nodule growth. The baseline volume, mass, and mean CT value were larger in the inva- sive adenocarcinoma group than in the adenocarcinoma in situ group (all P < .01). The shortest volume doubling time was observed in the invasive adenocarcinoma group, followed by the minimally invasive adenocarcinoma group and the adenocarcinoma in situ group. A shorter mass doubling time was observed in the minimally invasive adenocarcinoma group than in the adenocarcinoma in situ group (all P < .02). CONCLUSION As age increases, the risk of pulmonary subsolid nodule growth increases by 4% each year, and part-solid nodules have a 3 times higher risk of growth compared to non-solid nodules in patients with no history of cancer. Subsolid nodules with more aggressive pathological charac- teristics grow at a faster rate.

Growth and division mechanisms by which genetic resisters emerge from the rifampicin-surviving population of differentially antibiotic-susceptible mycobacterial subpopulations.

We recently reported the de novo emergence of unusually high numbers of antibiotic resisters from the in vitro cultures of Mycobacterium tuberculosis and Mycobacterium smegmatis surviving in the presence of minimum bactericidal concentration (MBC) of antituberculosis antibiotics. The resisters emerged due to multiple asymmetric divisions of elongated mother cells containing multiple nucleoids and multiple septae. We had earlier found a minor subpopulation of short-sized cells (SCs) and a major subpopulation of normal-sized cells (NCs) (10% and 90%, respectively, of the whole population), with significant difference in antibiotic susceptibility and resister generation frequency, in the in vitro cultures of M. tuberculosis, M. smegmatis, and Mycobacterium xenopi, as well as in pulmonary tuberculosis patients' sputum. However, the mechanisms of growth and division promoting the emergence of antibiotic resisters from these subpopulations remained unknown. Therefore, here, we took up the first-time study to find out the mechanism of growth and division by which antibiotic resisters emerge from the antibiotic-surviving population of the two subpopulations of M. smegmatis. M. smegmatis SCs and NCs were fractionated from mid-log phase cultures using Percoll gradient centrifugation; their purity was checked and exposed to 10×, 2×, and 0.4× MBC of rifampicin for 120 h. The colony-forming units (CFUs) were determined on rifampicin-free plates for the total population and on rifampicin-containing plates for scoring rifampicin resisters. The phenotype and the morphology of the cells at various stages of the exposure were determined using transmission electron microscopy. The dynamic growth and division mechanisms of the cells to emerge as rifampicin resisters were monitored using live-cell time-lapse imaging. The rifampicin resisters were sequenced for mutations in the rifampicin resistance determining region of rpoB gene. Statistical significance was calculated using two-tailed paired t-test, with *P ≤ 0.05 and **P ≤ 0.01. Multinucleated and multiseptated elongated cells emerged from their respective antibiotic-surviving populations. They produced a large number of sibling-daughter cells through multiple asymmetric divisions in short durations, showing abnormally high spurts in CFUs of antibiotic resisters. The CFUs were several-fold higher than that expected from the mass-doubling time of the subpopulations. Despite this commonality, the subpopulations showed specific differences in their response to different multiples of their respective MBC of rifampicin. Mycobacterial subpopulations come out of rifampicin stress by undergoing multiple nucleoid replications, multiple septation for nucleoid segregation, and acquisition of antibiotic target-specific mutations, followed by multiple asymmetric divisions to generate unusually a large number of rifampicin resisters. Because we had earlier shown that SCs and NCs are present in the pulmonary tuberculosis patients' sputum, the present findings have clinical relevance on the mechanism of emergence of antibiotic-resistant strains from mycobacterial subpopulations.

ES23.05 GGN Issues

As low-dose computed tomography (LDCT) is increasingly popular, the possibility of detecting ground-glass nodules (GGN) has also increased significantly, which was uncommon in the era of chest radiography as a regular health examination. Although the term GGN can be focal interstitial fibrosis, inflammation, hemorrhage and malignancies, we mainly focus on GGN that is pathologically malignant. A substantial proportion of GGNs detected at screening CT are transient [1]. It is important to avoid overtreatment of transient GGNs. The possibility of spontaneous regression of newly diagnosed GGN should always be considered before invasive treatment is decided. Several sets of guidelines are already available for the management of GGNs found on CT scans or via CT screening [2,3]. Obviously, there are differences in the recommendations of each guideline for some specific scenarios. One of the important reasons is that the correlation between radiographic appearance and histologic diagnosis is far from reliable [4]. Some people simply thought GGN referred to the site without blocking of alveolar cavity pathologically, and ground-glass opacity (GGO) components therefore represented the lepidic growth pattern of adenocarcinoma. However, both lepidic and non-lepidic growth patterns can present as GGNs on CT images [5]. So, GGO is a rather unspecific radiologic feature involving various pathologic conditions. The radiologic feature of GGO has a significant impact on clinical results. Several studies have revealed that the presence of a GGO component was a significantly favorable prognostic factor in early-stage NSCLC [6,7]. In Fu’s study, the 5-year RFS rates were 100% in the pure-GGN group no matter what histological type [8]. Such excellent prognosis naturally makes people think that it is not only the result of surgery, but also that these lesions might be indolent tumors even in the absence of any kind of treatment. Concerns have been raised about the possibility that premature surgical resection may represent‘overtreatment’. This is a good understanding of why Dr. Sepesi takes timing and indications for resection as an important issue for the treatment of GGN [9]. Although the precise surgical indications have not been determined, for obvious reasons a higher ratio of solid component need resected more urgently. The presence of a solid component is associated with a much higher risk for invasive adenocarcinoma [10]. However, there were different measurement results using different attenuation thresholds in regard to defining the solid or ground-glass components. Visual assessment of nodule morphologic structure on chest CT images Is still commonly used in clinical practice. However, interobserver and intraobserver discrepancies in nodule categorization cannot be ignored, especially disagreement on the size and presence of a solid component may lead to different management in the majority of cases with such discrepancies [11]. In order to evaluate the growth rate of GGNs in an accurate, reproducible, and sensitive manner, some measures on three-dimensional volumetry, such as volume doubling time (VDT) and mass doubling time (MDT), are getting more and more applications. High-grade invasive tumors show significantly shorter VDTs and MDTs than do low-grade invasive ones [12]. If the measurements of VDT and MDT can be popularized, they have the potential to become important references for evaluating GGN surgical indications. Furthermore, since the framework combining radiomics with deep learning (RDL) has the potential to predict high-grade lung adenocarcinoma, RDL might be a supplemental tool to screen high-risk subgroup in GGN patients for pathologists in the future [13]. Given the low aggressiveness of GGNs, it has been proposed that some GGNs meeting certain conditions could be cured by a limited surgical resection instead of a major lung resection. The trial of JCOG 0201 made a lot of exploratory work [14,15]. Long-term survival of patients in the trial of JCOG 0201 revealed that radiologic criteria of a consolidation/tumor ratio (CTR) ≤0.25 and a size≤ 2.0 cm or CRT ≤0.50 and a size ≤ 3.0 cm were both able to define a homogeneous subgroup with an excellent prognosis. Whether these radiologic criteria can be validated, we need to wait for the results of some prospective clinical trials, such as JCOG1211 [16] and GALGB140503 (NCT00499330). In term of surgical extent, the extent of lymphadenectomy is also an important issue. In Zhang’s study, there was no lymph node metastasis in GGN patients with CTR≤0.50, regardless of the tumor size [17]. This raises the question as to whether lymph nodes dissection is necessary in patients whose CT features manifest as GGO prominently. In summary, the decision to treat GGNs must consider both the aggressiveness of nodules and competing risks. Although more and more evidence come from retrospective studies on sublobar resection, high-quality evidence is needed to support a paradigm shift in clinical practice. There will be an ever-increasing tumor localization technology development to facilitate care for surgical management of GGNs. GGN, Surgery, Management

ALMA Lensing Cluster Survey: An ALMA Galaxy Signposting a MUSE Galaxy Group at z = 4.3 Behind “El Gordo”

Abstract We report the discovery of a Multi Unit Spectroscopic Explorer (MUSE) galaxy group at z = 4.32 lensed by the massive galaxy cluster ACT-CL J0102-4915 (aka El Gordo) at z = 0.87, associated with a 1.2 mm source that is at a 2.07 ± 0.88 kpc projected distance from one of the group galaxies. Three images of the whole system appear in the image plane. The 1.2 mm source has been detected within the Atacama Large Millimetre/submillimetre Array (ALMA) Lensing Cluster Survey (ALCS). As this ALMA source is undetected at wavelengths λ &lt; 2 μm, its redshift cannot be independently determined, however, the three lensing components indicate that it belongs to the same galaxy group at z = 4.32. The four members of the MUSE galaxy group have low to intermediate stellar masses (∼107–1010 M ⊙) and star formation rates (SFRs) of 0.4–24 M ⊙ yr−1, resulting in high specific SFRs (sSFRs) for two of them, which suggest that these galaxies are growing fast (with stellar mass doubling times of only ∼2 × 107 yr). This high incidence of starburst galaxies is likely a consequence of interactions within the galaxy group, which is compact and has high velocity dispersion. Based on the magnification-corrected sub-/millimeter continuum flux density and estimated stellar mass, we infer that the ALMA source is classified as an ordinary ultra-luminous infrared galaxy (with associated dust-obscured SFR ∼ 200–300 M ⊙ yr−1) and lies on the star formation main sequence. This reported case of an ALMA/MUSE group association suggests that some presumably isolated ALMA sources are in fact signposts of richer star-forming environments at high redshifts.

Natural history of pathologically confirmed pulmonary subsolid nodules with deep learning-assisted nodule segmentation.

To explore the natural history of pulmonary subsolid nodules (SSNs) with different pathological types by deep learning-assisted nodule segmentation. Between June 2012 and June 2019, 95 resected SSNs with preoperative long-term follow-up were enrolled in this retrospective study. SSN detection and segmentation were performed on preoperative follow-up CTs using the deep learning-based Dr. Wise system. SSNs were categorized into invasive adenocarcinoma (IAC, n = 47) and non-IAC (n = 48) groups; according to the interval change during the preoperative follow-up, SSNs were divided into growth (n = 68), nongrowth (n = 22), and new emergence (n = 5) groups. We analyzed the cumulative percentages and pattern of SSN growth and identified significant factors for IAC diagnosis and SSN growth. The mean preoperative follow-up was 42.1 ± 17.0 months. More SSNs showed growth or new emergence in the IAC than in the non-IAC group (89.4% vs. 64.6%, p = 0.009). Volume doubling time was non-significantly shorter for IACs than for non-IACs (1436.0 ± 1188.2 vs. 2087.5 ± 1799.7 days, p = 0.077). Median mass doubling time was significantly shorter for IACs than for non-IACs (821.7 vs. 1944.1 days, p = 0.001). Lobulated sign (p = 0.002) and SSN mass (p = 0.004) were significant factors for differentiating IACs. IACs showed significantly higher cumulative growth percentages than non-IACs in the first 70 months of follow-up. The growth pattern of SSNs may conform to the exponential model. The initial volume (p = 0.042) was a predictor for SSN growth. IACs appearing as SSNs showed an indolent course. The mean growth rate was larger for IACs than for non-IACs. SSNs with larger initial volume are more likely to grow. • Invasive adenocarcinomas (IACs) appearing as subsolid nodules (SSNs), with a mean volume doubling time (VDT) of 1436.0 ± 1188.2 days and median mass doubling time (MDT) of 821.7 days, showed an indolent course. • The VDT was shorter for IACs than for non-IACs (1436.0 ± 1188.2 vs. 2087.5 ± 1799.7 days), but the difference was not significant (p = 0.077). The median MDT was significantly shorter for IACs than for non-IACs (821.7 vs. 1944.1 days, p = 0.001). • SSNs with lobulated sign and larger mass (> 390.5 mg) may very likely be IACs. SSNs with larger initial volume are more likely to grow.

Volume and Mass Doubling Time of Lung Adenocarcinoma according to WHO Histologic Classification.

ObjectiveThis study aimed to evaluate the tumor doubling time of invasive lung adenocarcinoma according to the International Association of the Study for Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) histologic classification.Materials and MethodsAmong the 2905 patients with surgically resected lung adenocarcinoma, we retrospectively included 172 patients (mean age, 65.6 ± 9.0 years) who had paired thin-section non-contrast chest computed tomography (CT) scans at least 84 days apart with the same CT parameters, along with 10 patients with squamous cell carcinoma (mean age, 70.9 ± 7.4 years) for comparison. Three-dimensional semiautomatic segmentation of nodules was performed to calculate the volume doubling time (VDT), mass doubling time (MDT), and specific growth rate (SGR) of volume and mass. Multivariate linear regression, one-way analysis of variance, and receiver operating characteristic curve analyses were performed.ResultsThe median VDT and MDT of lung cancers were as follows: acinar, 603.2 and 639.5 days; lepidic, 1140.6 and 970.1 days; solid/micropapillary, 232.7 and 221.8 days; papillary, 599.0 and 624.3 days; invasive mucinous, 440.7 and 438.2 days; and squamous cell carcinoma, 149.1 and 146.1 days, respectively. The adjusted SGR of volume and mass of the solid-/micropapillary-predominant subtypes were significantly shorter than those of the acinar-, lepidic-, and papillary-predominant subtypes. The histologic subtype was independently associated with tumor doubling time. A VDT of 465.2 days and an MDT of 437.5 days yielded areas under the curve of 0.791 and 0.795, respectively, for distinguishing solid-/micropapillary-predominant subtypes from other subtypes of lung adenocarcinoma.ConclusionThe tumor doubling time of invasive lung adenocarcinoma differed according to the IASCL/ATS/ERS histologic classification.

Star–disc alignment in the protoplanetary discs: SPH simulation of the collapse of turbulent molecular cloud cores

ABSTRACT We perform a series of three-dimensional smoothed particle hydrodynamics (SPH) simulations to study the evolution of the angle between the protostellar spin and the protoplanetary disc rotation axes (the star–disc angle ψsd) in turbulent molecular cloud cores. While ψsd at the protostar formation epoch exhibits broad distribution up to ∼130°, ψsd decreases (≲ 20°) in a time-scale of ∼104 yr. This time-scale of the star–disc alignment, talignment, corresponds basically to the mass doubling time of the central protostar, in which the protostar forgets its initial spin direction due to the mass accretion from the disc. Values of ψsd both at t = 102 yr and t = 105 yr after the protostar formation are independent of the ratios of thermal and turbulent energies to gravitational energy of the initial cloud cores: α = Ethermal/|Egravity| and γturb = Eturbulence/|Egravity|. We also find that a warped disc is possibly formed by the turbulent accretion flow from the circumstellar envelope.

Long-term follow-up of persistent pulmonary pure ground-glass nodules with deep learning-assisted nodule segmentation.

To investigate the natural history of persistent pulmonary pure ground-glass nodules (pGGNs) with deep learning-assisted nodule segmentation. Between January 2007 and October 2018, 110 pGGNs from 110 patients with 573 follow-up CT scans were included in this retrospective study. pGGN automatic segmentation was performed on initial and all follow-up CT scans using the Dr. Wise system based on convolution neural networks. Subsequently, pGGN diameter, density, volume, mass, volume doubling time (VDT), and mass doubling time (MDT) were calculated automatically. Enrolled pGGNs were categorized into growth, 52 (47.3%), and non-growth, 58 (52.7%), groups according to volume growth. Kaplan-Meier analyses with the log-rank test and Cox proportional hazards regression analysis were conducted to analyze the cumulative percentages of pGGN growth and identify risk factors for growth. The mean follow-up period of the enrolled pGGNs was 48.7 ± 23.8months. The median VDT of the 52 pGGNs having grown was 1448 (range, 339-8640) days, and their median MDT was 1332 (range, 290-38,912) days. The 12-month, 24.7-month, and 60.8-month cumulative percentages of pGGN growth were 10%, 25.5%, and 51.1%, respectively, and they significantly differed among the initial diameter, volume, and mass subgroups (all p < 0.001). The growth pattern of pGGNs may conform to the exponential model. Lobulated sign (p = 0.044), initial mean diameter (p < 0.001), volume (p = 0.003), and mass (p = 0.023) predicted pGGN growth. Persistent pGGNs showed an indolent course. Deep learning can assist in accurately elucidating the natural history of pGGNs. pGGNs with lobulated sign and larger initial diameter, volume, and mass are more likely to grow. • The pure ground-glass nodule (pGGN) segmentation accuracy of the Dr. Wise system based on convolution neural networks (CNNs) was 96.5% (573/594). • The median volume doubling time (VDT) of 52 pure ground-glass nodules (pGGNs) having grown was 1448days (range, 339-8640days), and their median mass doubling time (MDT) was 1332days (range, 290-38,912days). The mean time to growth in volume was 854 ± 675days (range, 116-2856days). • The 12-month, 24.7-month, and 60.8-month cumulative percentages of pGGN growth were 10%, 25.5%, and 51.1%, respectively, and they significantly differed among the initial diameter, volume, and mass subgroups (all p values < 0.001). The growth pattern of pure ground-glass nodules may conform to exponential model.

Dynamics of cluster-forming hub-filament systems: The case of the high-mass star-forming complex Monoceros R2.

High-mass stars and star clusters commonly form within hub-filament systems. Monoceros R2 (hereafter Mon R2), at a distance of 830 pc, harbors one of the closest such systems, making it an excellent target for case studies. We investigate the morphology, stability and dynamical properties of the Mon R2 hub-filament system. We employ observations of the 13CO and C18O 1→0 and 2→1 lines obtained with the IRAM-30m telescope. We also use H2 column density maps derived from Herschel dust emission observations. We identified the filamentary network in Mon R2 with the DisPerSE algorithm and characterized the individual filaments as either main (converging into the hub) or secondary (converging to a main filament) filaments. The main filaments have line masses of 30-100 M ⊙ pc-1 and show signs of fragmentation, while the secondary filaments have line masses of 12-60 M ⊙ pc-1 and show fragmentation only sporadically. In the context of Ostriker's hydrostatic filament model, the main filaments are thermally supercritical. If non-thermal motions are included, most of them are trans-critical. Most of the secondary filaments are roughly transcritical regardless of whether non-thermal motions are included or not. From the morphology and kinematics of the main filaments, we estimate a mass accretion rate of 10-4-10-3 M ⊙ yr-1 into the central hub. The secondary filaments accrete into the main filaments with a rate of 0.1-0.4×10-4 M ⊙ yr-1. The main filaments extend into the central hub. Their velocity gradients increase towards the hub, suggesting acceleration of the gas.We estimate that with the observed infall velocity, the mass-doubling time of the hub is ~ 2:5 Myr, ten times larger than the free-fall time, suggesting a dynamically old region. These timescales are comparable with the chemical age of the Hii region. Inside the hub, the main filaments show a ring- or a spiral-like morphology that exhibits rotation and infall motions. One possible explanation for the morphology is that gas is falling into the central cluster following a spiral-like pattern.

Particle accretion onto planets in discs with hydrodynamic turbulence

The growth process of protoplanets can be sped up by accreting a large number of solid, pebble-sized objects that are still present in the protoplanetary disc. It is still an open question on how efficient this process works in realistic turbulent discs. We investigate the accretion of pebbles in turbulent discs that are driven by the purely hydrodynamical vertical shear instability (VSI). For this purpose, we performed global 3D simulations of locally isothermal, VSI turbulent discs that have embedded protoplanetary cores from 5 to 100 M⊕, which are placed at 5.2 au distance from the star. In addition, we followed the evolution of a swarm of embedded pebbles of different sizes under the action of drag forces between gas and particles in this turbulent flow. Simultaneously, we performed a set of comparison simulations for laminar viscous discs where the particles experience stochastic kicks. For both cases, we measured the accretion rate onto the cores as a function of core mass and Stokes number (τs) of the particles and compared these values to recent magneto-rotational instability (MRI) turbulence simulations. Overall the dynamic is very similar for the particles in the VSI turbulent disc and the laminar case with stochastic kicks. For small mass planets (i.e. 5–10 M⊕), well-coupled particles with τs = 1, which have a size of about 1 m at this location, we find an accretion efficiency (rate of particles accreted over drifting inwards) of about 1.6−3%. For smaller and larger particles, this efficiency is higher. However, the fast inwards drift for τs = 1 particles makes them the most effective for rapid growth, leading to mass doubling times of about 20 000 yr. For masses between 10 and 30 M⊕ the core reaches the pebble isolation mass and the particles are trapped at the pressure maximum just outside of the planet, shutting off further particle accretion.

The volume and mass growth of persisted pulmonary nodules detected in low-dose CT screening and its influence factors

Objective: To evaluate the changes of volume and mass of pulmonary nodules which were detected in low-dose computed tomography (LDCT) screening, and to analyze the influencing factors. Methods: This retrospective study analyzed the CT images of the participants who underwent at least two chest LDCT scanning from March 2009 to December 2015 in National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. The inclusion criteria was the nodule diameter ≥6 mm; the volume growth was defined as ≥20%. Fifty-one pulmonary nodules (PNs) were selected among 51 enrolled participants (26 men and 25 women). According to characteristic of nodule and risk stratification of participant, the nodules were classified into different groups (10 non-solid nodules, 17 part-solid nodules and 24 solid nodules; 14 PNs in high-risk group, 12 PNs in moderate-risk group and 25 PNs in low-risk group). The Lung-VCAR software was used to measure the diameter and volume of the PNs, and all nodules were calculated for the volume doubling time (VDT) and mass doubling time (MDT). Results: Among the 51 PNs, the diameter of 33 nodules increased more than 1.5 mm while 18 nodules increased less than 1.5 mm. The median VDT of part-solid nodules was 364 days, which was shorter than that of non-solid nodules and solid nodules (761 and 819 days, respectively), the differences were statistically significant (both P<0.05). The median MDT of part-solid nodules was 351 days, which was lower than that of non-solid nodules and solid nodules (772 days and 840 days, respectively). The difference was statistically significant (P<0.05). The median VDT and MDT of the pulmonary nodules in the high-risk group were 181 days and 256 days, respectively, which were lower than those in the low risk group (1 037 days and 1 035 days, respectively). VDT has good correlation with MDT (r=0.909, P<0.001). Conclusions: Both the characteristic of PNs and the risk status of the participants could affect the growth of nodules in LDCT screening. The part-solid nodules and high-risk group nodules grew relatively faster, which should be closely focused on. Compared with the two-dimensional diameter, the three-dimensional quantitative indicators (VDT and MDT) were more sensitive for nodule growth. The mass changes of part-solid nodules were earlier than that of volume.

Malignant solitary pulmonary nodules: assessment of mass growth rate and doubling time at follow-up CT.

The differentiation of benign and malignant solitary pulmonary nodules (SPNs), especially subsolid nodules, is still challenging because of the small size, slow growth, and atypical imaging characteristics of these nodules. We aimed to determine the significance of mass growth rate (MGR) and mass doubling time (MDT) at follow-up CT of malignant SPNs. This retrospective study included 167 patients (169 SPNs, diameter 8-30 mm). Among the 169 SPNs, 114 malignant SPNs were classified into three types: pure ground-glass nodules (pGGNs), part-solid nodules (pSNs), and solid nodules (SNs). These patients were followed up for at least 3 months. Three-dimensional manual segmentation was performed for all these nodules, and the intra- and inter-observer variabilities of diameter, volume, and mass measurement were assessed. From initial and follow-up CT scans, growth rates of the diameter, volume, and mass of the SPNs were compared. MDT and volume doubling time (VDT) were calculated and were compared among groups. Mass measurements had the best inter-observer consistency and intra-observer repeatability; the coefficients of variation of the mass measurements were the smallest. The mean growth rates of the diameter, volume, and mass of pGGNs, pSNs, and SNs significantly differed at different time points (P<0.001). Mean MDTs and VDTs of pGGNs, pSNs, and SNs were 655 vs. 848 days, 462 vs. 598 days, and 230 vs. 267 days, respectively (P<0.05). Mass measurements are an objective and accurate indicator in SPN assessment. During a 2-year follow-up, the mean growth rates of the diameter, volume, and mass of pGGNs, pSNs, and SNs differed at different time points, the greatest difference was observed in mean MGR. Mean MDT of malignant SPNs is less than the mean VDT.