ABSTRACT
We investigate how star formation quenching proceeds within central and satellite galaxies using spatially resolved spectroscopy from the SDSS-IV MaNGA DR15. We adopt a complete sample of ...star formation rate surface densities (ΣSFR), derived in Bluck et al. (2020), to compute the distance at which each spaxel resides from the resolved star forming main sequence (ΣSFR − Σ* relation): ΔΣSFR. We study galaxy radial profiles in ΔΣSFR, and luminosity weighted stellar age (AgeL), split by a variety of intrinsic and environmental parameters. Via several statistical analyses, we establish that the quenching of central galaxies is governed by intrinsic parameters, with central velocity dispersion (σc) being the most important single parameter. High mass satellites quench in a very similar manner to centrals. Conversely, low mass satellite quenching is governed primarily by environmental parameters, with local galaxy overdensity (δ5) being the most important single parameter. Utilizing the empirical MBH − σc relation, we estimate that quenching via AGN feedback must occur at $M_{\rm BH} \ge 10^{6.5-7.5} \, \mathrm{M}_{\odot }$, and is marked by steeply rising ΔΣSFR radial profiles in the green valley, indicating ‘inside-out’ quenching. On the other hand, environmental quenching occurs at overdensities of 10–30 times the average galaxy density at z∼ 0.1, and is marked by steeply declining ΔΣSFR profiles, indicating ‘outside-in’ quenching. Finally, through an analysis of stellar metallicities, we conclude that both intrinsic and environmental quenching must incorporate significant starvation of gas supply.
Abstract
STUDY QUESTION
Are meiotic and developmental competence of human oocytes from small (2–8 mm) antral follicles improved by applying an optimized IVM method involving a prematuration step in ...presence of C-Type Natriuretic Peptide (CNP) followed by a maturation step in presence of FSH and Amphiregulin (AREG)?
SUMMARY ANSWER
A strategy involving prematuration culture (PMC) in the presence of CNP followed by IVM using FSH + AREG increases oocyte maturation potential leading to a higher availability of Day 3 embryos and good-quality blastocysts for single embryo transfer.
WHAT IS KNOWN ALREADY
IVM is a minimal-stimulation ART with reduced hormone-related side effects and risks for the patients, but the approach is not widely used because of an efficiency gap compared to conventional ART. In vitro systems that enhance synchronization of nuclear and cytoplasmic maturation before the meiotic trigger are crucial to optimize human IVM systems. However, previous PMC attempts have failed in sustaining cumulus-oocyte connections throughout the culture period, which prohibited a normal cumulus-oocyte communication and precluded an adequate response by the cumulus-oocyte complex (COC) to the meiotic trigger.
STUDY DESIGN, SIZE, DURATION
A first prospective study involved sibling oocytes from a group of 15 patients with polycystic ovary syndrome (PCOS) to evaluate effects of a new IVM culture method on oocyte nuclear maturation and their downstream developmental competence. A second prospective study in an additional series of 15 women with polycystic ovaries characterized and fine-tuned the culture conditions.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Fifteen women with PCOS (according to Rotterdam criteria) underwent IVM treatment after 3–5 days of highly purified human menopausal gonadotropin (HP-hMG) stimulation and no human chorionic gonadotropin (hCG) trigger before oocyte retrieval. A first study was designed with sibling oocytes to prospectively evaluate the impact of an IVM culture method: 24 h PMC with CNP + 30 h IVM with FSH and AREG, on embryo yield, in comparison to the standard (30 h) IVM clinical protocol (Group I, n = 15).
A second prospective study was performed in 15 women with polycystic ovaries, to characterize and optimize the PMC conditions (Group II, n = 15). The latter study involved the evaluation of oocyte meiotic arrest, the preservation of cumulus-oocyte transzonal projections (TZPs), the patterns of oocyte chromatin configuration and cumulus cells apoptosis following the 24 and 46 h PMC. Furthermore, oocyte developmental potential following PMC (24 and 46 h) + IVM was also evaluated. The first 20 good-quality blastocysts from PMC followed by IVM were analysed by next generation sequencing to evaluate their aneuploidy rate.
MAIN RESULTS AND THE ROLE OF CHANCE
PMC in presence of CNP followed by IVM using FSH and AREG increased the meiotic maturation rate per COC to 70%, which is significantly higher than routine standard IVM (49%; P ≤ 0.001). Hence, with the new system the proportion of COCs yielding transferable Day 3 embryos and good-quality blastocysts increased compared to routine standard IVM (from 23 to 43%; P ≤ 0.001 and from 8 to 18%; P ≤ 0.01, respectively). CNP was able to prevent meiosis resumption for up to 46 h. After PMC, COCs had preserved cumulus-oocyte TZPs. The blastocysts obtained after PMC + IVM did not show increased aneuploidy rates as compared to blastocysts from conventional ART.
LIMITATIONS REASONS FOR CAUTION
The novel IVM approach in PCOS patients was tested in oocytes derived from small antral follicles which have an intrinsically low developmental potential. Validation of the system would be required for COCs from different (larger) follicular sizes, which may involve further adjustment of PMC conditions. Furthermore, considering that this is a novel strategy in human IVM treatment, its global efficiency needs to be confirmed in large prospective randomized controlled trials. The further application in infertile patients without PCOS, e.g. cancer patients, remains to be evaluated.
WIDER IMPLICATIONS OF THE FINDINGS
The findings of this pilot study suggest that the efficiency gap between IVM and conventional IVF can be reduced by fine-tuning of the culture methods. This novel strategy opens new perspectives for safe and patient-friendly ART in patients with PCOS.
STUDY FUNDING/COMPETING INTEREST(S)
IVM research at the Vrije Universiteit Brussel has been supported by grants from: the Institute for the Promotion of Innovation by Science and Technology in Flanders (Agentschap voor Innovatie door Wetenschap en Technologie—IWT, project 110680); the Fund for Research Flanders (Fonds Wetenschappelijk Onderzoek–Vlaanderen—FWO, project G.0343.13), the Belgian Foundation Against Cancer (HOPE project, Dossier C69). The authors have no conflicts of interest.
SDSS-IV MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is the largest integral-field unit (IFU) spectroscopy survey to date, aiming to observe a statistically representative sample of ...10,000 low-redshift galaxies. In this paper, we study the reliability of the emission-line fluxes and kinematic properties derived by the MaNGA Data Analysis Pipeline (DAP). We describe the algorithmic choices made in the DAP with regards to measuring emission-line properties, and the effect of our adopted strategy of simultaneously fitting the continuum and line emission. The effects of random errors are quantified by studying various fit-quality metrics, idealized recovery simulations, and repeat observations. This analysis demonstrates that the emission lines are well fit in the vast majority of the MaNGA data set and the derived fluxes and errors are statistically robust. The systematic uncertainty on emission-line properties introduced by the choice of continuum templates is also discussed. In particular, we test the effect of using different stellar libraries and simple stellar-population models on the derived emission-line fluxes and the effect of introducing different tying prescriptions for the emission-line kinematics. We show that these effects can generate large (>0.2 dex) discrepancies at low signal-to-noise ratio and for lines with low equivalent width (EW); however, the combined effect is noticeable even for H EW > 6 . We provide suggestions for optimal use of the data provided by SDSS data release 15 and propose refinements on the DAP for future MaNGA data releases.
Abstract
The tight correlation between total galaxy stellar mass and star formation rate (SFR) has become known as the star-forming main sequence. Using ∼487 000 spaxels from galaxies observed as ...part of the Sloan Digital Sky Survey Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we confirm previous results that a correlation also exists between the surface densities of star formation (ΣSFR) and stellar mass (Σ⋆) on kpc scales, representing a ‘resolved’ main sequence. Using a new metric (ΔΣSFR), which measures the relative enhancement or deficit of star formation on a spaxel-by-spaxel basis relative to the resolved main sequence, we investigate the SFR profiles of 864 galaxies as a function of their position relative to the global star-forming main sequence (ΔSFR). For galaxies above the global main sequence (positive ΔSFR) ΔΣSFR is elevated throughout the galaxy, but the greatest enhancement in star formation occurs at small radii (<3 kpc, or 0.5Re). Moreover, galaxies that are at least a factor of 3 above the main sequence show diluted gas phase metallicities out to 2Re, indicative of metal-poor gas inflows accompanying the starbursts. For quiescent/passive galaxies that lie at least a factor of 10 below the star-forming main sequence, there is an analogous deficit of star formation throughout the galaxy with the lowest values of ΔΣSFR in the central 3 kpc. Our results are in qualitative agreement with the ‘compaction’ scenario in which a central starburst leads to mass growth in the bulge and may ultimately precede galactic quenching from the inside-out.
•Convolutional neural networks are the most used architecture.•End-to-end methods are preferred over hybrid methods.•Recall is the most used metric for detection and localization tasks.•Intersection ...over Union is highly used in segmentation.•A common validation framework, including dataset and metrics, is missing.
Colorectal cancer has a great incidence rate worldwide, but its early detection significantly increases the survival rate. Colonoscopy is the gold standard procedure for diagnosis and removal of colorectal lesions with potential to evolve into cancer and computer-aided detection systems can help gastroenterologists to increase the adenoma detection rate, one of the main indicators for colonoscopy quality and predictor for colorectal cancer prevention. The recent success of deep learning approaches in computer vision has also reached this field and has boosted the number of proposed methods for polyp detection, localization and segmentation. Through a systematic search, 35 works have been retrieved. The current systematic review provides an analysis of these methods, stating advantages and disadvantages for the different categories used; comments seven publicly available datasets of colonoscopy images; analyses the metrics used for reporting and identifies future challenges and recommendations. Convolutional neural networks are the most used architecture together with an important presence of data augmentation strategies, mainly based on image transformations and the use of patches. End-to-end methods are preferred over hybrid methods, with a rising tendency. As for detection and localization tasks, the most used metric for reporting is the recall, while Intersection over Union is highly used in segmentation. One of the major concerns is the difficulty for a fair comparison and reproducibility of methods. Even despite the organization of challenges, there is still a need for a common validation framework based on a large, annotated and publicly available database, which also includes the most convenient metrics to report results. Finally, it is also important to highlight that efforts should be focused in the future on proving the clinical value of the deep learning based methods, by increasing the adenoma detection rate.
ABSTRACT The "main sequence of galaxies"-defined in terms of the total star formation rate versus the total stellar mass M*-is a well-studied tight relation that has been observed at several ...wavelengths and at different redshifts. All earlier studies have derived this relation from integrated properties of galaxies. We recover the same relation from an analysis of spatially resolved properties, with integral field spectroscopic (IFS) observations of 306 galaxies from the CALIFA survey. We consider the SFR surface density in units of log(M yr−1 Kpc−2) and the stellar mass surface density in units of log(M Kpc−2) in individual spaxels that probe spatial scales of 0.5-1.5 Kpc. This local relation exhibits a high degree of correlation with small scatter ( = 0.23 dex), irrespective of the dominant ionization source of the host galaxy or its integrated stellar mass. We highlight (i) the integrated star formation main sequence formed by galaxies whose dominant ionization process is related to star formation, for which we find a slope of 0.81 0.02; (ii) for the spatially resolved relation obtained with the spaxel analysis, we find a slope of 0.72 0.04; and (iii) for the integrated main sequence, we also identified a sequence formed by galaxies that are dominated by an old stellar population, which we have called the retired galaxies sequence.
Variations in the intensity of high-latitude Northern Hemisphere summer insolation, driven largely by precession of the equinoxes, are widely thought to control the timing of Late Pleistocene glacial ...terminations. However, recently it has been suggested that changes in Earth's obliquity may be a more important mechanism. We present a new speleothem-based North Atlantic marine chronology that shows that the penultimate glacial termination (Termination II) commenced 141,000 ± 2500 years before the present, too early to be explained by Northern Hemisphere summer insolation but consistent with changes in Earth's obliquity. Our record reveals that Terminations I and II are separated by three obliquity cycles and that they started at near-identical obliquity phases.
We measured the gas abundance profiles in a sample of 122 face-on spiral galaxies observed by the CALIFA survey and included all spaxels whose line emission was consistent with star formation. This ...type of analysis allowed us to improve the statistics with respect to previous studies, and to properly estimate the oxygen distribution across the entire disc to a distance of up to 3−4 disc effective radii (re). We confirm the results obtained from classical H ii region analysis. In addition to the general negative gradient, an outer flattening can be observed in the oxygen abundance radial profile. An inner drop is also found in some cases. There is a common abundance gradient between 0.5 and 2.0 re of αO / H = − 0.075 dex /re with a scatter of σ = 0.016 dex /re when normalising the distances to the disc effective radius. By performing a set of Kolmogorov-Smirnov tests, we determined that this slope is independent of other galaxy properties, such as morphology, absolute magnitude, and the presence or absence of bars. In particular, barred galaxies do not seem to display shallower gradients, as predicted by numerical simulations. Interestingly, we find that most of thegalaxies in the sample with reliable oxygen abundance values beyond ~2 effective radii (57 galaxies) present a flattening of the abundance gradient in these outer regions. This flattening is not associated with any morphological feature, which suggests that it is a common property of disc galaxies. Finally, we detect a drop or truncation of the abundance in the inner regions of 27 galaxies in the sample; this is only visible for the most massive galaxies.
As a consequence of the COVID-19 pandemic, different measures have been implemented by governments from each affected country. Such measures usually involve restrictions on the movement of citizens, ...and have had a profound effect on usual activities and timetables. As a result of school closures and strict restrictions regarding going outside home, children have been one of the most disadvantaged population groups during the lockdown period. We therefore aimed to investigate potential health risk behaviors amongst isolated pre-school and school-aged children. We retrieved relevant articles from MEDLINE, Web of Science, PsycInfo, and Scopus databases to describe identified health-related behaviors (i.e. screen exposure, environmental influence, physical activity and fitness, sedentariness, sleep patterns, eating habits, psychological response, body composition, and injuries) in relation to social isolation and social deprivation of children without previous illness or conditions. This review depicts the potential health-related behaviors according to related literature, and put the focus on future short and long-term sequels of social isolation. Socio-affective complications and insufficient physical activity are underscored as two of the main concerns, particularly among socio-economic deprived children. Both issues could be effectively addressed with either adequate parental or community guidance.
•Social isolation may worsen several health-related behaviors.•Socioeconomic issues could either exacerbate or mitigate social isolation effects.•Socio-affective complications might be derived from prolonged COVID-19 lockdown.•Insufficient physical activity and too much screen exposure could be among the main consequences of COVID-19 lockdown.
We present a statistical analysis of the environments of 11 supernovae (SNe) which occurred in six nearby galaxies (z ≲ 0.016). All galaxies were observed with MUSE, the high spatial resolution ...integral-field spectrograph mounted to the 8 m VLT UT4. These data enable us to map the full spatial extent of host galaxies up to ∼3 effective radii. In this way, not only can one characterize the specific host environment of each SN, one can compare their properties with stellar populations within the full range of other environments within the host. We present a method that consists of selecting all H ii regions found within host galaxies from 2D extinction-corrected Hα emission maps. These regions are then characterized in terms of their Hα equivalent widths, star formation rates and oxygen abundances. Identifying H ii regions spatially coincident with SN explosion sites, we are thus able to determine where within the distributions of host galaxy e.g. metallicities and ages each SN is found, thus providing new constraints on SN progenitor properties. This initial pilot study using MUSE opens the way for a revolution in SN environment studies where we are now able to study multiple environment SN progenitor dependencies using a single instrument and single pointing.
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