The GIRAFFE Inner Bulge Survey (GIBS) Zoccali, M; Vasquez, S; Gonzalez, O A ...
Astronomy and astrophysics (Berlin),
3/2017, Letnik:
599
Journal Article
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Context. Several recent studies have demonstrated that the Galactic bulge hosts two components with different mean metallicities, and possibly different spatial distribution and kinematics. As a ...consequence, both the metallicity distribution and the radial velocity of bulge stars vary across different lines of sight. Aims. We present here the metallicity distribution function of red clump stars in 26 fields spread across a wide area of the bulge, with special emphasis on fields close to Galactic plane, at latitudes b= -2degrees and b= -1degrees, that have not been explored before. Methods. This paper includes new metallicities from a sample of approximately 5000 K giant stars, observed at spectral resolution R~ 6500, in the Calcium II Triplet region. These represent the main dataset from the GIRAFFE Inner Bulge Survey. As part of the same survey we have previously published results for a sample of approximately 600 K giant stars, at latitude b~ -4degrees, derived from higher resolution spectra (R= 22 500). Results. The combined sample allows us to trace and characterize the metal poor and metal rich bulge populations down to the inner bulge. We present a density map for each of the two components. Contrary to expectations from previous works, we found the metal poor population to be more centrally concentrated than the metal rich one, and with a more axisymmetric spatial distribution. The metal rich population, on the other hand, is arranged in a boxy distribution, consistent with an edge-on bar. By coupling metallicities and radial velocities we show that the metal poor population has a velocity dispersion that varies rather mildly with latitude. On the contrary, the metal rich population has a low velocity dispersion far from the plane (b= -8.5degrees), yet has a steeper gradient with latitude, becoming higher than the metal poor one in the innermost field (b= -1degrees). Conclusions. This work provides new observational constraints on the actual chemodynamical properties of the Galactic bulge, that will help discrimination between different formation models.
We have combined optical and near-infrared data of known RR Lyrae (RRL) stars in the bulge in order to study the spatial distribution of its metal-poor component by measuring precise reddening values ...and distances of 7663 fundamental-mode RRL stars with high-quality photometry. We obtain a distance to the Galactic center of R sub(0) = 8.33 + or - 0.05 + or - 0.14 kpc. We find that the spatial distribution of the RRL stars differs from the structures traced by the predominantly metal-rich red clump (RC) stars. Unlike the RC stars, the RRL stars do not trace a strong bar, but have a more spheroidal, centrally concentrated distribution, showing only a slight elongation in its very center. We find a hint of bimodality in the density distribution at high southern latitudes (b < -5degrees), which needs to be confirmed by extending the areal coverage of the current census. The different spatial distributions of the metal-rich and metal-poor stellar populations suggest that the Milky Way has a composite bulge.
We conducted an analysis of global forest cover to reveal that 70% of remaining forest is within 1 km of the forest's edge, subject to the degrading effects of fragmentation. A synthesis of ...fragmentation experiments spanning multiple biomes and scales, five continents, and 35 years demonstrates that habitat fragmentation reduces biodiversity by 13 to 75% and impairs key ecosystem functions by decreasing biomass and altering nutrient cycles. Effects are greatest in the smallest and most isolated fragments, and they magnify with the passage of time. These findings indicate an urgent need for conservation and restoration measures to improve landscape connectivity, which will reduce extinction rates and help maintain ecosystem services.
Context. Three dimensional interstellar extinction maps provide a powerful tool for stellar population analysis. However, until now, these 3D maps were rather limited by sensitivity and spatial ...resolution. Aims. We use data from the VISTA Variables in the Via Lactea survey together with the Besançon stellar population synthesis model of the Galaxy to determine interstellar extinction as a function of distance in the Galactic bulge covering −10°<l< 10° and −10°<b< 5°. Methods. We adopted a recently developed method to calculate the colour excess. First we constructed the H − Ks vs. Ks and J − Ks vs. Ks colour−magnitude diagrams based on the VVV catalogues that matched 2MASS. Then, based on the temperature−colour relation for M giants and the distance-colour relations, we derived the extinction as a function of distance. The observed colours were shifted to match the intrinsic colours in the Besançon model as a function of distance iteratively. This created an extinction map with three dimensions: two spatial and one distance dimension along each line of sight towards the bulge. Results. We present a 3D extinction map that covers the whole VVV area with a resolution of 6′× 6′ for J − Ks and H − Ks using distance bins of 0.5 kpc. The high resolution and depth of the photometry allows us to derive extinction maps for a range of distances up to 10 kpc and up to 30 mag of extinction in AV (3.0 mag in AKs). Integrated maps show the same dust features and consistent values as other 2D maps. We discuss the spatial distribution of dust features in the line of sight, which suggests that there is much material in front of the Galactic bar, specifically between 5−7 kpc. We compare our dust extinction map with the high-resolution 12CO maps (NANTEN2) towards the Galactic bulge, where we find a good correlation between 12CO and AV. We determine the X factor by combining the CO map and our dust extinction map. Our derived average value X = 2.5 ± 0.47 × 1020 cm-2 K-1 km-1s is consistent with the canonical value of the Milky Way. The X-factor decreases with increasing extinction.
Context. As observational evidence steadily accumulates, the nature of the Galactic bulge has proven to be rather complex: the structural, kinematic, and chemical analyses often lead to contradictory ...conclusions. The nature of the metal-rich bulge – and especially of the metal-poor bulge – and their relation with other Galactic components, still need to be firmly defined on the basis of statistically significant high-quality data samples. Aims. We used the fourth internal data release of the Gaia-ESO survey to characterize the bulge metallicity distribution function (MDF), magnesium abundance, spatial distribution, and correlation of these properties with kinematics. Moreover, the homogeneous sampling of the different Galactic populations provided by the Gaia-ESO survey allowed us to perform a comparison between the bulge, thin disk, and thick disk sequences in the Mg/Fe vs. Fe/H plane in order to constrain the extent of their eventual chemical similarities. Methods. We obtained spectroscopic data for ~2500 red clump stars in 11 bulge fields, sampling the area −10° ≤ l ≤ + 8° and −10° ≤ b ≤ −4° from the fourth internal data release of the Gaia-ESO survey. A sample of ~6300 disk stars was also selected for comparison. Spectrophotometric distances computed via isochrone fitting allowed us to define a sample of stars likely located in the bulge region. Results. From a Gaussian mixture models (GMM) analysis, the bulge MDF is confirmed to be bimodal across the whole sampled area. The relative ratio between the two modes of the MDF changes as a function of b, with metal-poor stars dominating at high latitudes. The metal-rich stars exhibit bar-like kinematics and display a bimodality in their magnitude distribution, a feature which is tightly associated with the X-shape bulge. They overlap with the metal-rich end of the thin disk sequence in the Mg/Fe vs. Fe/H plane. On the other hand, metal-poor bulge stars have a more isotropic hot kinematics and do not participate in the X-shape bulge. Their Mg enhancement level and general shape in the Mg/Fe vs. Fe/H plane is comparable to that of the thick disk sequence. The position at which Mg/Fe starts to decrease with Fe/H, called the “knee”, is observed in the metal-poor bulge at Fe/H knee = −0.37 ± 0.09, being 0.06 dex higher than that of the thick disk. Although this difference is inside the error bars, it suggest a higher star formation rate (SFR) for the bulge than for the thick disk. We estimate an upper limit for this difference of Δ Fe/H knee = 0.24 dex. Finally, we present a chemical evolution model that suitably fits the whole bulge sequence by assuming a fast (<1 Gyr) intense burst of stellar formation that takes place at early epochs. Conclusions. We associate metal-rich stars with the bar boxy/peanut bulge formed as the product of secular evolution of the early thin disk. On the other hand, the metal-poor subpopulation might be the product of an early prompt dissipative collapse dominated by massive stars. Nevertheless, our results do not allow us to firmly rule out the possibility that these stars come from the secular evolution of the early thick disk. This is the first time that an analysis of the bulge MDF and α-abundances has been performed in a large area on the basis of a homogeneous, fully spectroscopic analysis of high-resolution, high S/N data.
Context. The Milky Way bulge is the nearest galactic bulge and the most readily accessible laboratory for studies of stellar populations in spheroids based on individual stellar abundances and ...kinematics. These studies are challenged by the strongly variable and often large extinction on a small spatial scale.Aims. We use the Vista Variables in the Via Lactea (VVV) ESO public survey data to measure extinction values in the complete area of the Galactic bulge covered by the survey at high resolution.Methods. We derive reddening values using the method described in Paper I. This is based on measuring the mean (J − Ks) color of red clump giants in small subfields of 2′ × 2′ to 6′ × 6′ in the following bulge area: − 10.3° ≤ b ≤ + 5.1° and − 10.0° ≤ l ≤ + 10.4°. To determine the reddening values E(J − Ks) for each region, we measure the RC color and compare it to the (J − Ks) color of RC stars measured in Baade’s Window, for which we adopt E(B − V) = 0.55. This allows us to construct a reddening map sensitive to small-scale variations minimizing the problems arising from differential extinction.Results. The significant reddening variations are clearly observed on spatial scales as small as 2′. We find good agreement between our extinction measurements and Schlegel maps in the outer bulge, but, as already stated in the literature the Schlegel maps are unreliable for regions within |b| ≲ 6°. In the inner regions, we compare our results with maps derived from DENIS and Spitzer surveys. While we find good agreement with other studies in the corresponding overlapping regions, our extinction map is of higher quality owing to both its higher resolution and a more complete spatial coverage of the bulge. We investigate the importance of differential reddening and demonstrate the need for high spatial resolution extinction maps for detailed studies of bulge stellar populations and structure.Conclusions. We present the first extinction map covering uniformly ~315 sq. deg. of the Milky Way bulge at high spatial resolution. We consider a 30 arcmin window at a latitude of b = −4°, which corresponds to a frequently studied low extinction window, the so-called Baade’s Window, and find that its AKs values can vary by up to 0.1 mag. Larger extinction variations are observed at lower Galactic latitudes. The extinction variations on scales of up to 2′−6′ must be taken into account when analyzing the stellar populations of the Galactic bulge.
Summary
Follicular helper T cells (Tfh) cells have been identified in the circulation and in tertiary lymphoid structures in chronic inflammation. Gingival tissues with periodontitis reflect chronic ...inflammation, so genomic footprints of Tfh cells should occur in these tissues and may differ related to aging effects. Macaca mulatta were used in a ligature‐induced periodontitis model adult group (aged 12–23 years); young group (aged 3–7 years). Gingival tissue and subgingival microbiome samples were obtained at matched healthy ligature‐induced disease and clinical resolution sites. Microarray analysis examined Tfh genes (n = 54) related to microbiome characteristics documented using 16S MiSeq. An increase in the major transcription factor of Tfh cells, BCL6, was found with disease in both adult and young animals, while master transcription markers of other T cell subsets were either decreased or showed minimal change. Multiple Tfh‐related genes, including surface receptors and transcription factors, were also significantly increased during disease. Specific microbiome patterns were significantly associated with profiles indicative of an increased presence/function of Tfh cells. Importantly, unique microbial complexes showed distinctive patterns of interaction with Tfh genes differing in health and disease and with the age of the animals. An increase in Tfh cell responsiveness occurred in the progression of periodontitis, affected by age and related to specific microbial complexes in the oral microbiome. The capacity of gingival Tfh cells to contribute to localized B cell activation and active antibody responses, including affinity maturation, may be critical for controlling periodontal lesions and contributing to limiting and/or resolving the lesions.
This study examined the characteristics of T follicular helper (Tfh) cells occurring in healthy and periodontitis affected gingival tissues using a nonhuman primate model of disease. Comparisons of the Tfh transcriptome were also examined across the lifespan to estimate age and disease effects on these cells. The study also identified oral microbiome bacterial consortia that strongly correlated with alterations in gene expression patterns related to Tfh functions.
This investigation evaluated the relationship of the oral microbiome and gingival transcriptome in health and periodontitis in nonhuman primates (Macaca mulatta). Subgingival plaque samples and ...gingival biopsies were collected from healthy sites and at sites undergoing ligature-induced periodontitis. Microbial samples were analyzed with 16S amplicon sequencing to identify bacterial profiles in young (3 to 7 y) and adult (12 to 23 y) animals. The gingival transcriptome was determined with a microarray analysis and focused on the expression level of 452 genes that are associated with the development of inflammation and innate and adaptive immune responses. Of the 396 total operational taxonomic units (OTUs) identified across the samples, 81.8% were detected in the young group and 99.5% in the adult group. Nevertheless, 58 of the OTUs composed 88% of the signal in adults, and 49 OTUs covered 91% of the OTU readouts in the young group. Correlation analyses between the microbiome members and specific gingival genes showed a high number of significant bacteria-gene correlations in the young healthy tissues, which decreased by 75% in diseased tissues. In contrast, these correlations increased by 2.5-fold in diseased versus healthy tissues of adult animals. Complexes of bacteria were delineated that related to specific sets of immune genes, differing in health and disease and in the young versus adult animals. The correlated gene profiles demonstrated selected pathway overrepresentation related to particular bacterial complexes. These results provide novel insights into microbiome changes with disease and the relationship of these changes to specific gene profiles and likely biologic activities occurring in healthy and diseased gingival tissues in this human-like periodontitis model.
Summary
The molecular changes underlying the higher risk of chronic inflammatory disorders during aging remain incompletely understood. Molecular variations in the innate immune response related to ...recognition and interaction with microbes at mucosal surfaces could be involved in aging‐related inflammation. We developed an ontology analysis of 20 nucleotide‐binding and oligomerization domain (NOD)‐like receptors (NLRs) and seven inflammasome‐related genes (IRGs) in healthy and inflamed/periodontitis oral mucosal tissues from young, adolescent, adult, and aged non‐human primates (Macaca mulatta) using the GeneChip® Rhesus Macaque Genome array. Validation of some of the significant changes was done by quantitative reverse transcription–polymerase chain reaction. The expression of NLRB/NAIP, NLRP12, and AIM2 increased with aging in healthy mucosa whereas NLRC2/NOD2 expression decreased. Although higher expression levels of some NLRs were generally observed with periodontitis in adult mucosal tissues (e.g. NLRB/NAIP, NLRP5, and NLRX1), various receptors (e.g. NLRC2/NOD2 and NLRP2) and the inflammasome adaptor protein ASC, exhibited a significant reduction in expression in aged periodontitis tissues. Accordingly, the expression of NLR‐activated innate immune genes, such as HBD3 and IFNB1, was impaired in aged but not adult periodontitis tissues. Both adult and aged tissues showed significant increase in interleukin‐1β expression. These findings suggest that the expression of a subset of NLRs appears to change with aging in healthy oral mucosa, and that aging‐related oral mucosal inflammation could involve an impaired regulation of the inflammatory and antimicrobial response associated with downregulation of specific NLRs and IRGs.
Artificial neural networks (ANN) are computationally based mathematical tools inspired by the fundamental cell of the nervous system, the neuron. ANN constitute a simplified artificial replica of the ...human brain consisting of parallel processing neural elements similar to neurons in living beings. ANN is able to store large amounts of experimental information to be used for generalization with the aid of an appropriate prediction model. ANN has proved useful for a variety of biological, medical, economic and meteorological purposes, and in agro-food science and technology. The olive oil industry has a substantial weight in Mediterranean's economy. The different steps of the olive oil production process, which include olive tree and fruit care, fruit harvest, mechanical and chemical processing, and oil packaging have been examined in depth with a view to their optimization, and so have the authenticity, sensory properties and other quality-related properties of olive oil. This paper reviews existing literature on the use of bioinformatics predictive methods based on ANN in connection with the production, processing and characterization of olive oil. It examines the state of the art in bioinformatics tools for optimizing or predicting its quality with a view to identifying potential deficiencies or aspects for improvement.
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