Since the end of the 1990s, the aerobiological network managed by the Regional Environmental Agency in Emilia-Romagna, Italy, started a systematic monitoring of different types of fungal spores, in ...particular Alternaria. This activity is of outstanding interest due to the various detrimental effects on human beings and on vegetation associated with Alternaria spores presence in the atmosphere. Daily concentration values of Alternaria spores are available from the Emilia-Romagna network in 10 stations. The availability of these data allows to set up a detailed analysis of the presence of Alternaria spores in different climatic and environmental settlements. The 19-year database of daily spore concentrations in most of the stations (1999–2017) can also support a preliminary analysis of climatic trends. A synthetic characterization of the main features associated with the presence and amount of Alternaria spores will be presented in this work. The period with the highest values of concentration in most of the measuring stations covers the warm season, with two main peaks of spore production in early and late summer. The most relevant trends for Alternaria season are mainly associated with an increase in the length of the period when spores are present. As for the amount of spores, signals are generally less evident, indicating a predominant decrease in the spore amount.
This study is related to an overall analysis of the most relevant pollen season modifications as they emerge from the aerobiological monitoring activity in the network of stations in Emilia-Romagna, ...a region located in Northern Italy. The taxa selected for the study are among the most important from an allergenic point of view. The selected period goes from 1991 to 2017 in order to have a similar length for all the different taxa in all the stations, regardless of their date of activation. Statistical analysis of the time series of some pollen season indicators has been carried out in the period, with the aim of pointing out the most relevant changes in the ensemble of the monitoring stations. The available database lasting more than 25 years can be the basis for a robust statistical analysis of the long-term trends in the time series of pollen seasonal indicators. The stations are operating throughout the whole Emilia-Romagna territory, spanning a range of climatic conditions from the inner Po Valley to the coastal area. Results of the trend analysis indicate that the starting and the peak dates of the pollen season are in prevalent advance. This is true both for most herbaceous taxa, as well as for several arboreal ones. As for pollen production, a different behaviour characterizes herbaceous and arboreal taxa; in fact, a generally decreasing trend interests all herbaceous taxa, while a prevalent increasing trend is present in several of the latter. Pollen season indicators are certainly more directly affected by the changes associated with the meteo-climatic forcing and are possibly more influenced by climatic change.
The cosmological process of hydrogen (H i) reionization in the intergalactic medium is thought to be driven by UV photons emitted by star-forming galaxies and ionizing active galactic nuclei (AGN). ...The contribution of quasars (QSOs) to H i reionization at z > 4 has been traditionally believed to be quite modest. However, this view has been recently challenged by new estimates of a higher faint-end UV luminosity function (LF). To set firmer constraints on the emissivity of AGN at z < 6, we here make use of complete X-ray-selected samples including deep Chandra and new Cosmic Evolution Survey data, capable to efficiently measure the 1 Ryd comoving AGN emissivity up to z ~ 5-6 and down to 5 mag fainter than probed by current optical surveys, without any luminosity extrapolation. We find good agreement between the log N sub( H) ... 21-22 cm super( -2) X-ray LF and the optically selected QSO LF at all redshifts for M sub( 1450) less than or equal to -23. The full range of the log N sub( H) ... 21-22 cm super( -2) LF (M sub( 1450) less than or equal to -17) was then used to quantify the contribution of AGN to the critical value of photon budget needed to keep the Universe ionized. We find that the contribution of ionizing AGN at z = 6 is as small as 1-7 per cent, and very unlikely to be greater than 30 per cent, thus excluding an AGN-dominated reionization scenario. (ProQuest: ... denotes formulae/symbols omitted.)
As matter accretes onto the central supermassive black holes in active galactic nuclei (AGNs), X-rays are emitted. We present a population synthesis model that accounts for the summed X-ray emission ...from growing black holes; modulo the efficiency of converting mass to X-rays, this is effectively a record of the accreted mass. We need this population synthesis model to reproduce observed constraints from X-ray surveys: the X-ray number counts, the observed fraction of Compton-thick AGNs log (NH/cm−2) > 24, and the spectrum of the cosmic X-ray background (CXB), after accounting for selection biases. Over the past decade, X-ray surveys by XMM-Newton, Chandra, NuSTAR, and Swift-BAT have provided greatly improved observational constraints. We find that no existing X-ray luminosity function (XLF) consistently reproduces all these observations. We take the uncertainty in AGN spectra into account and use a neural network to compute an XLF that fits all observed constraints, including observed Compton-thick number counts and fractions. This new population synthesis model suggests that, intrinsically, 50% 9% (56% 7%) of all AGNs within z 0.1 (1.0) are Compton-thick.
We investigate the multi-wavelength properties of host galaxies of 3701 X-ray-selected active galactic nuclei (AGNs) out to z ∼ 5 in the Chandra-COSMOS Legacy Survey. Thanks to the extensive ...multi-wavelength photometry available in the COSMOS field, we derive AGN luminosities, host stellar masses, and star formation rates (SFRs) via a multi-component SED fitting technique. Type 1 and Type 2 AGNs follow the same intrinsic L2-10 keV-L6 m relation, suggesting that mid-infrared emission is a reasonably good measure of the AGN accretion power regardless of obscuration. We find that there is a strong increase in Type 1 AGN fraction toward higher AGN luminosity, possibly due to the fact that Type 1 AGNs tend to be hosted by more massive galaxies. The AGN luminosity and SFR are consistent with an increase toward high stellar mass, while the Mstellar dependence is weaker toward the high-mass end, which could be interpreted as a consequence of quenching both star formation and AGN activity in massive galaxies. AGN host galaxies tend to have SFRs that are consistent with normal star-forming galaxies, independent of AGN luminosities. We confirm that black hole accretion rate and SFR are correlated up to z ∼ 5, when forming stars. The majority (∼73%) of our AGN sample are faint in the far-infrared, implying that the moderate-luminosity AGNs seem to be still active after the star formation is suppressed. It is not certain whether AGN activity plays a role in quenching the star formation. We conclude that both AGN activity and star formation might be more fundamentally related to host stellar mass.
We present an X-ray stacking analysis of ∼75,000 star-forming galaxies between 0.1 < z < 5.0 using the Chandra COSMOS-Legacy survey to study the X-ray emission of low-luminosity active galactic ...nuclei (AGN) and its connection to host galaxy properties. The stacks at z < 0.9 have luminosity limits as low as 1040-1041 erg s−1, a regime in which X-ray binaries (XRBs) can dominate the X-ray emission. Comparing the measured luminosities to established XRB scaling relations, we find that the redshift evolution of the luminosity per star formation rate (SFR) of XRBs depends sensitively on the assumed obscuration and may be weaker than previously found. The XRB scaling relation based on stacks from the Chandra Deep Field South overestimates the XRB contribution to the COSMOS high specific SFR stacks, possibly due to a bias affecting the CDF-S stacks because of their small galaxy samples. After subtracting the estimated XRB contribution from the stacks, we find that most stacks at z > 1.3 exhibit a significant X-ray excess indicating nuclear emission. The AGN emission is strongly correlated with stellar mass but does not exhibit an additional correlation with SFR. The hardness ratios of the high-redshift stacks indicate that the AGN are substantially obscured (NH ∼ 1023 cm−2). These obscured AGN are not identified by IRAC color selection and have LX ∼ 1041-1043 erg s−1, consistent with accretion at an Eddington rate of ∼10−3 onto 107-108 M black holes. Combining our results with other X-ray studies suggests that AGN obscuration depends on stellar mass and an additional variable, possibly the Eddington rate.
Abstract
We characterize the average X-ray and radio properties of quiescent galaxies (QGs) with
log
(
M
⋆
/
M
⊙
)
>
10
at 0 <
z
< 5. QGs are photometrically selected from the latest COSMOS2020 ...catalog. We conduct the stacking analysis of X-ray images of the Chandra COSMOS Legacy Survey for individually undetected QGs. Thanks to the large sample and deep images, the stacked X-ray signal is significantly detected up to
z
∼ 5. The average X-ray luminosity cannot be explained by the X-ray luminosity of X-ray binaries, suggesting that the low-luminosity active galactic nuclei (AGNs) ubiquitously exist in QGs. Moreover, the X-ray AGN luminosity of QGs at
z
> 1.5 is higher than that of star-forming galaxies (SFGs), derived in the same manner as QGs. The stacking analysis of the VLA-COSMOS images is conducted for the identical sample, and the radio signal for QGs is also detected up to
z
∼ 5. We find that the radio AGN luminosity of QGs at
z
> 1.5 is also higher than SFGs, which is in good agreement with the X-ray analysis. The enhanced AGN activity in QGs suggested by the individual analysis in the X-ray and radio wavelength supports its important role for quenching at high redshift. Their enhanced AGN activity is less obvious at
z
< 1.5, which can be interpreted as an increasing role of others at lower redshifts, such as environmental quenching.
We report on the spectroscopic confirmation of a large-scale structure around the luminous
z
= 6.31 quasi-stellar object (QSO) SDSS J1030+0524, powered by a one billion solar mass black hole. The ...structure is populated by at least six members, namely, four Lyman-break galaxies (LBGs), and two Lyman alpha emitters (LAEs). The four LBGs were identified among a sample of 21
i
-band dropouts with
z
AB
< 25.5 selected up to projected separations of 5 physical Mpc (15 arcmin) from the QSO. Their redshifts were determined through multi-object spectroscopic observations at 8−10 m class telescopes lasting up to eight hours. The two LAEs were identified in a 6 h VLT/MUSE observation centered on the QSO. The redshifts of the six galaxies cover the range between 6.129−6.355. Assuming that the peculiar velocities are negligible, this range corresponds to radial separations of ±5 physical Mpc from the QSO, that is comparable to the projected scale of the observed LBG distribution on the sky. We conservatively estimate that this structure is significant at a level > 3.5
σ
and that the level of the galaxy overdensity is at least 1.5−2 within the large volume sampled (∼780 physical Mpc
3
). The spectral properties of the six member galaxies (Ly
α
strength and UV luminosity) are similar to those of field galaxies at similar redshifts. This is the first spectroscopic identification of a galaxy overdensity around a supermassive black hole in the first billion years of the Universe. Our finding lends support to the idea that the most distant and massive black holes form and grow within massive (>10
12
M
⊙
) dark matter halos in large-scale structures and that the absence of earlier detections of such systems is likely due to observational limitations.
Abstract
It is unclear whether the establishment of apical–basal cell polarity during the generation of epithelial lumens requires molecules acting at the plasma membrane/actin interface. Here, we ...show that the I-BAR-containing IRSp53 protein controls lumen formation and the positioning of the polarity determinants aPKC and podocalyxin. Molecularly, IRSp53 acts by regulating the localization and activity of the small GTPase RAB35, and by interacting with the actin capping protein EPS8. Using correlative light and electron microscopy, we further show that IRSp53 ensures the shape and continuity of the opposing plasma membrane of two daughter cells, leading to the formation of a single apical lumen. Genetic removal of IRSp53 results in abnormal renal tubulogenesis, with altered tubular polarity and architectural organization. Thus, IRSp53 acts as a membrane curvature-sensing platform for the assembly of multi-protein complexes that control the trafficking of apical determinants and the integrity of the luminal plasma membrane.
Cell polarity refers to the intrinsic asymmetry of cells, including the orientation of the cytoskeleton. It affects cell shape and structure as well as the distribution of proteins and organelles. In ...migratory cells, front-rear polarity is essential and dictates movement direction. While the link between the cytoskeleton and nucleus is well-studied, we aim to investigate if front-rear polarity can be transmitted to the nucleus. We show that the knock-down of emerin, an integral protein of the nuclear envelope, abolishes preferential localization of several nuclear proteins. We propose that the frontally biased localization of the endoplasmic reticulum, through which emerin reaches the nuclear envelope, is sufficient to generate its observed bias. In primary emerin-deficient myoblasts, its expression partially rescues the polarity of the nucleus. Our results demonstrate that front-rear cell polarity is transmitted to the nucleus and that emerin is an important determinant of nuclear polarity.
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