Pulsational frequencies of the eclipsing delta-Scuti star HD 172189

The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.Comment: 6 pages, 7 figure

Mobile Ion-Driven Modulation of Electronic Conductivity Explains Long-Timescale Electrical Response in Lead Iodide Perovskite Thick Pellets

The favorable optoelectronic properties of metal halide perovskites have been used for X- and γ-ray detection, solar energy, and optoelectronics. Large electronic mobility, reduced recombination losses of the electron–hole pairs, and high sensitivity upon ionizing irradiation have fostered great attention on technological realizations. Nevertheless, the recognized mixed ionic-electronic transport properties of hybrid perovskites possess severe limitations as far as long-timescale instabilities and degradation issues are faced. Several effects are attributed to the presence of mobile ions such as shielding of the internal electrical field upon biasing and chemical interaction between intrinsic moving defects and electrode materials. Ion-originated modulations of electronic properties constitute an essential peace of knowledge to further progress into the halide perovskite device physics and operating modes. Here, ionic current and electronic impedance of lead methylammonium iodide perovskite thick pellets are independently monitored, showing self-consistent patterns. Our findings point to a coupling of ionic and electronic properties as a dynamic doping effect caused by moving ions that act as mobile dopants. The electronic doping profile changes within the bulk as a function of the actual ion inner distribution, then producing a specific time dependence in the electronic conductivity that reproduces time patterns of the type , a clear fingerprint of diffusive transport. Values for the iodine-related defect diffusivity in the range of Dion ∼ 10–8 cm2 s–1, which corresponds to ionic mobilities of about μion ∼ 10–6 cm2 V–1 s–1, are encountered. Technological realizations based on thick perovskite layers would benefit from this fundamental information, as far as long-timescale current stabilization is concerned.This work has received funding from the European Union’s Horizon 2020 research and innovation program under the Photonics Public Private Partnership (www.photonics21.org) with the project PEROXIS under the grant agreement N° 871336. M.G.-B. acknowledges Generalitat Valenciana for a grant (number GRISOLIAP/2018/073)

Developmental regulation of apical endocytosis controls epithelial patterning in vertebrate tubular organs

© 2015 Macmillan Publishers Limited. Epithelial organs develop through tightly coordinated events of cell proliferation and differentiation in which endocytosis plays a major role. Despite recent advances, how endocytosis regulates the development of vertebrate organs is still unknown. Here we describe a mechanism that facilitates the apical availability of endosomal SNARE receptors for epithelial morphogenesis through the developmental upregulation of plasmolipin (pllp) in a highly endocytic segment of the zebrafish posterior midgut. The protein PLLP (Pllp in fish) recruits the clathrin adaptor EpsinR to sort the SNARE machinery of the endolysosomal pathway into the subapical compartment, which is a switch for polarized endocytosis. Furthermore, PLLP expression induces apical Crumbs internalization and the activation of the Notch signalling pathway, both crucial steps in the acquisition of cell polarity and differentiation of epithelial cells. We thus postulate that differential apical endosomal SNARE sorting is a mechanism that regulates epithelial patterning.MINECO (BFU2011-22622) and CONSOLIDER (CSD2009-00016); Fundación Obra Social `La Caixa' PhD fellowship. G.A. was supported by the Amarouto Program for senior researchers from the Comunidad Autónoma de Madrid.Peer Reviewe

Smoothelin-like 2 Inhibits Coronin-1B to Stabilize the Apical Actin Cortex during Epithelial Morphogenesis

The actin cortex is involved in many biological processes and needs to be significantly remodeled during cell differentiation. Developing epithelial cells construct a dense apical actin cortex to carry out their barrier and exchange functions. The apical cortex assembles in response to three-dimensional (3D) extracellular cues, but the regulation of this process during epithelial morphogenesis remains unknown. Here, we describe Smoothelin-like 2 (SMTNL2) function, a member of the smooth-muscle related Smoothelin protein family, in apical cortex maturation. SMTNL2 is induced during the development of multiple epithelial tissues and localizes to the apical and junctional actin cortex in intestinal and kidney epithelial cells. SMTNL2 deficiency leads to membrane herniations in the apical domain of epithelial cells, indicative of cortex abnormalities. We find that SMTNL2 binds to actin filaments and is required to slow down the turnover of apical actin. We also characterize the SMTNL2 proximal interactome and find that SMTNL2 executes its functions partly through inhibition of Coronin-1B. While Coronin-1B-mediated actin dynamics are required for early morphogenesis, its sustained activity is detrimental for the mature apical shape. SMTNL2 binds to Coronin-1B through its N-terminal coiled-coil region and negates its function to stabilize the apical cortex. In sum, our results unveil a mechanism for regulating actin dynamics during epithelial morphogenesis, providing critical insights on the developmental control of the cellular corte

Genome-Wide Analysis of the Yeast Transcriptome Upon Heat and Cold Shock

DNA arrays were used to measure changes in transcript levels as yeast cells responded to temperature shocks. The number of genes upregulated by temperature shifts from 30 ℃ to 37℃ or 45℃ was correlated with the severity of the stress. Pre-adaptation of cells, by growth at 37 ℃ previous to the 45℃ shift, caused a decrease in the number of genes related to this response. Heat shock also caused downregulation of a set of genes related to metabolism, cell growth and division, transcription, ribosomal proteins, protein synthesis and destination. Probably all of these responses combine to slow down cell growth and division during heat shock, thus saving energy for cell rescue. The presence of putative binding sites for Xbp1p in the promoters of these genes suggests a hypothetical role for this transcriptional repressor, although other mechanisms may be considered. The response to cold shock (4℃) affected a small number of genes, but the vast majority of those genes induced by exposure to 4 ℃ were also induced during heat shock; these genes share in their promoters cis-regulatory elements previously related to other stress responses

High-sensitivity high-resolution X-ray imaging with soft-sintered metal halide perovskites

To realize the potential of artificial intelligence in medical imaging, improvements in imaging capabilities are required, as well as advances in computing power and algorithms. Hybrid inorganic–organic metal halide perovskites, such as methylammonium lead triiodide (MAPbI3), offer strong X-ray absorption, high carrier mobilities (µ) and long carrier lifetimes (τ), and they are promising materials for use in X-ray imaging. However, their incorporation into pixelated sensing arrays remains challenging. Here we show that X-ray flat-panel detector arrays based on microcrystalline MAPbI3 can be created using a two-step manufacturing process. Our approach is based on the mechanical soft sintering of a freestanding absorber layer and the subsequent integration of this layer on a pixelated backplane. Freestanding microcrystalline MAPbI3 wafers exhibit a sensitivity of 9,300 µC Gyair–1 cm–2 with a μτ product of 4 × 10–4 cm2 V–1, and the resulting X-ray imaging detector, which has 508 pixels per inch, combines a high spatial resolution of 6 line pairs per millimetre with a low detection limit of 0.22 nGyair per frame

Desert dust outbreak in the Canary Islands (February 2020): assessment and impacts

World Weather Research Programme (WWRP 2021–1

Polarity, cell division, and out-of-equilibrium dynamics control the growth of epithelial structures

The growth of a well-formed epithelial structure is governed by mechanical constraints, cellular apico-basal polarity, and spatially controlled cell division. Here we compared the predictions of a mathematical model of epithelial growth with the morphological analysis of 3D epithelial structures. In both in vitro cyst models and in developing epithelial structures in vivo, epithelial growth could take place close to or far from mechanical equilibrium, and was determined by the hierarchy of time-scales of cell division, cell-cell rearrangements, and lumen dynamics. Equilibrium properties could be inferred by the analysis of cell-cell contact topologies, and the nonequilibrium phenotype was altered by inhibiting ROCK activity. The occurrence of an aberrant multilumen phenotype was linked to fast nonequilibrium growth, even when geometric control of cell division was correctly enforced. We predicted and verified experimentally that slowing down cell division partially rescued a multilumen phenotype induced by altered polarity. These results improve our understanding of the development of epithelial organs and, ultimately, of carcinogenesi

Spatial and Temporal Variations in the Annual Pollen Index Recorded by Sites Belonging to the Portuguese Aerobiology Network

This study presents the findings of a 10-year survey carried out by the Portuguese Aerobiology Network (RPA) at seven pollen-monitoring stations: five mainland stations (Oporto, Coimbra, Lisbon, Évora and Portimão) and two insular stations [Funchal (Madeira archipelago) and Ponta Delgada (Azores archipelago)]. The main aim of the study was to examine spatial and temporal variations in the Annual Pollen Index (API) with particular focus on the most frequently recorded pollen types. Pollen monitoring (2003–2012) was carried out using Hirst-type volumetric spore traps, following the minimum recommendations proposed by the European Aerobiology Society Working Group on Quality Control. Daily pollen data were examined for similarities using the Kruskal–Wallis nonparametric test and multivariate regression trees. Simple linear regression analysis was used to describe trends in API. The airborne pollen spectrum at RPA stations is dominated by important allergenic pollen types such as Poaceae, Olea and Urticaceae. Statistically significant differences were witnessed in the API recorded at the seven stations. Mean API is higher in the southern mainland cities, e.g. Évora, Lisbon and Portimão, and lower in insular and littoral cities. There were also a number of significant trends in API during the 10-year study. This report identifies spatial and temporal variations in the amount of airborne pollen recorded annually in the Portuguese territory. There were also a number of significant changes in API, but no general increases in the amount of airborne pollen

Preparing the COROT space mission: incidence and characterisation of pulsation in the Lower Instability Strip

By pursuing the goal to find new variables in the COROT field-of-view we characterised a sample of stars located in the lower part of the instability strip. Our sample is composed of stars belonging to the disk population in the solar neighbourhood. We found that 23% of the stars display multiperiodic light variability up to few mmag of amplitude. uvbyBeta photometry fixed most of the variables in the middle of the instability strip and high-resolution spectroscopy established that they have vsin i>100 km/s. The comparison with delta Sct stars in the whole Galaxy shows slightly different features, i.e., most delta Sct stars have a 0.05-mag redder (b-y)_0 index and lower vsin i values. Additional investigation in the open cluster NGC 6633 confirms the same incidence of variability, i.e., around 20%. The wide variety of pulsational behaviours of delta Sct stars (including unusual objects such as a variable beyond the blue edge or a rapidly rotating high-amplitude pulsator) makes them very powerful asteroseismic tools to be used by COROT. Being quite common among bright stars, delta Sct stars are suitable targets for optical observations from space.Comment: 9 pages, 9 figures Accepted for publication in Astronomy & Astrophysics, Main Journa