A Study of the B-V Colour Temperature Relation

We attempt to construct a B-V colour temperature relation for stars in the least model dependent way employing the best modern data. The fit we obtained with the form Teff = Teff((B-V)0,[Fe/H],log g) is well constrained and a number of tests show the consistency of the procedures for the fit. Our relation covers from F0 to K5 stars with metallicity [Fe/H] = -1.5 to +0.3 for both dwarfs and giants. The residual of the fit is 66 K, which is consistent with what are expected from the quality of the present data. Metallicity and surface gravity effects are well separated from the colour dependence. Dwarfs and giants match well in a single family of fit, differing only in log g. The fit also detects the Galactic extinction correction for nearby stars with the amount E(B-V) = 0.26 +/-0.03 mag/kpc. Taking the newly obtained relation as a reference we examine a number of B-V colour temperature relations and atmosphere models available in the literature. We show the presence of a systematic error in the colour temperature relation from synthetic calculations of model atmospheres; the systematic error across K0 to K5 dwarfs is 0.04-0.05 mag in B-V, which means 0.25-0.3 mag in Mv for the K star range. We also argue for the error in the temperature scale used in currently popular stellar population synthesis models; synthetic colours from these models are somewhat too blue for aged elliptical galaxies. We derive the colour index of the sun (B-V)sun = 0.627 +/-0.018, and discuss that redder colours (e.g., 0.66-0.67) often quoted in the literature are incompatible with the colour-temperature relation.Comment: AASLaTeX (aaspp4.sty),36 pages (13 figures included), submitted to Astronomical Journal, replaced (typo in author name

Illuminating phenylazopyridines to photoswitch metabotropic glutamate receptors: from the flask to the animals

Phenylazopyridines are photoisomerizable compounds with high potential to control biological functions with light. We have obtained a series of phenylazopyridines with light dependent activity as negative allosteric modulators (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5). Here we describe the factors needed to achieve an operational molecular photoisomerization and its effective translation into in vitro and in vivo receptor photoswitching, which includes zebrafish larva motility and the regulation of the antinociceptive effects in mice. The combination of light and some specific phenylazopyridine ligands displays atypical pharmacological profiles, including light-dependent receptor overactivation, which can be observed both in vitro and in vivo. Remarkably, the localized administration of light and a photoswitchable compound in the peripheral tissues of rodents or in the brain amygdalae results in an illumination-dependent analgesic effect. The results reveal a robust translation of the phenylazopyridine photoisomerization to a precise photoregulation of biological activity

Aorto-venous fistula between an abdominal aortic aneurysm and an aberrant renal vein: a case report

<p>Abstract</p> <p>Introduction</p> <p>The potential complications of an abdominal aortic aneurysm include rupture, compression of surrounding structures, thrombo-embolic events and fistula. The most common site of arterio-venous fistula is the inferior vena cava. Fistula involving a renal vein is particularly uncommon.</p> <p>Case presentation</p> <p>This report describes a 54-year-old Caucasian woman who was admitted to the emergency department with fatigue, severe dyspnea and bilateral lower limb edema. In the first instance this anamnesis suggested possible heart failure. In fact, our patient presented with multi-organ system failure due to a fistula between an infra-renal aortic aneurysm and an aberrant retro-aortic renal vein.</p> <p>Conclusions</p> <p>To our knowledge, this is the first report of a woman with a fistula between an infra-renal aortic aneurysm and an aberrant retro-aortic left renal vein. Aorto-venous fistulas may be asymptomatic or may present with symptoms characteristic of arterio-venous shunting and/or aneurysm rupture. This type of fistula is a rare cause of heart failure. Clinical examination and imaging are essential for detection.</p

Impaired neural development in a zebrafish model for Lowe syndrome

Lowe syndrome, which is characterized by defects in the central nervous system, eyes and kidneys, is caused by mutation of the phosphoinositide 5-phosphatase OCRL1. The mechanisms by which loss of OCRL1 leads to the phenotypic manifestations of Lowe syndrome are currently unclear, in part, owing to the lack of an animal model that recapitulates the disease phenotype. Here, we describe a zebrafish model for Lowe syndrome using stable and transient suppression of OCRL1 expression. Deficiency of OCRL1, which is enriched in the brain, leads to neurological defects similar to those reported in Lowe syndrome patients, namely increased susceptibility to heat-induced seizures and cystic brain lesions. In OCRL1-deficient embryos, Akt signalling is reduced and there is both increased apoptosis and reduced proliferation, most strikingly in the neural tissue. Rescue experiments indicate that catalytic activity and binding to the vesicle coat protein clathrin are essential for OCRL1 function in these processes. Our results indicate a novel role for OCRL1 in neural development, and support a model whereby dysregulation of phosphoinositide metabolism and clathrin-mediated membrane traffic leads to the neurological symptoms of Lowe syndrome

High-speed optical mapping of heart and brain voltage activities in zebrafish larvae exposed to environmental contaminants

Data availability: Data will be made available on request.Supplementary data are available online at https://www.sciencedirect.com/science/article/pii/S235218642300192X?via%3Dihub#appSB .Copyright © 2023 The Author(s). Environmental contaminants represent a poorly understood ecotoxicological and health risk. Here, we advanced a high-speed optical mapping (OM) technique to non-invasively track voltage dynamics in living zebrafish larvae’s heart and brain and investigate the effects of selected pesticides. OM allowed high resolution ( 17x) and fast acquisition (100 to 200 frames/s) of the voltage signal generated in the heart and brain after immersion of the zebrafish larvae in a voltage-sensitive dye. First, we used varying temperatures (20 °C to 25 °C) to test the adequacy of OM in capturing cardiac and brain voltage changes. Then, we tested the effects of glyphosate or a selected pesticide cocktail (2 to 120 h post-fertilization), accounting for their environmental thresholds and mimicking high-level exposure. Glyphosate (0.1 and 1000 g/L) and the pesticide cocktail (0.1 and 10 g/L) did not alter cardiac activity, except for a trend increase in heart rate variability at high glyphosate dose. Fourier transform (FT) analyses indicated that glyphosate reduced the abundance of low-amplitude voltage activities in the brain at the target low-frequency range of 0.2–15 Hz. The anatomical fragmentation of the brain into four regions, right and left diencephalon (RD and LD) and right and left optic tectum (ROT and LOT), confirmed the impact of glyphosate on the larvae brain and revealed a specific adaptation to the pesticide cocktail in the RD and ROT regions. In summary, OM captured heart and brain voltage changes in zebrafish larvae, with discrete patterns of brain depolarization in the presence of specific water contaminants. Here we discuss the relevance of these findings to ecotoxicology and exposome research.This work was supported by ANR-Hepatobrain and Epidimicmac ANSES to NM, and “Soutien à la Recherche 2021” of the University of Montpellier and Fondation pour la Recherche sur le Cerveau, France: Espoir en tête 2022/23 to AGT. Partially funded by OptoFish ANSES, ANR-EpiCatcher, ANR/Era-Net Neu-Vasc to NM and the Fondation pour la Recherche Médicale, France (FRM, grant DPC2017 to M.E.M)

Modern optical astronomy: technology and impact of interferometry

The present `state of the art' and the path to future progress in high spatial resolution imaging interferometry is reviewed. The review begins with a treatment of the fundamentals of stellar optical interferometry, the origin, properties, optical effects of turbulence in the Earth's atmosphere, the passive methods that are applied on a single telescope to overcome atmospheric image degradation such as speckle interferometry, and various other techniques. These topics include differential speckle interferometry, speckle spectroscopy and polarimetry, phase diversity, wavefront shearing interferometry, phase-closure methods, dark speckle imaging, as well as the limitations imposed by the detectors on the performance of speckle imaging. A brief account is given of the technological innovation of adaptive-optics (AO) to compensate such atmospheric effects on the image in real time. A major advancement involves the transition from single-aperture to the dilute-aperture interferometry using multiple telescopes. Therefore, the review deals with recent developments involving ground-based, and space-based optical arrays. Emphasis is placed on the problems specific to delay-lines, beam recombination, polarization, dispersion, fringe-tracking, bootstrapping, coherencing and cophasing, and recovery of the visibility functions. The role of AO in enhancing visibilities is also discussed. The applications of interferometry, such as imaging, astrometry, and nulling are described. The mathematical intricacies of the various `post-detection' image-processing techniques are examined critically. The review concludes with a discussion of the astrophysical importance and the perspectives of interferometry.Comment: 65 pages LaTeX file including 23 figures. Reviews of Modern Physics, 2002, to appear in April issu

Force Sensing by Piezo Channels in Cardiovascular Health and Disease

Mechanical forces are fundamental in cardiovascular biology, and deciphering the mechanisms by which they act remains a testing frontier in cardiovascular research. Here, we raise awareness of 2 recently discovered proteins, Piezo1 and Piezo2, which assemble as transmembrane triskelions to combine exquisite force sensing with regulated calcium influx. There is emerging evidence for their importance in endothelial shear stress sensing and secretion, NO generation, vascular tone, angiogenesis, atherosclerosis, vascular permeability and remodeling, blood pressure regulation, insulin sensitivity, exercise performance, and baroreceptor reflex, and there are early suggestions of relevance to cardiac fibroblasts and myocytes. Human genetic analysis points to significance in lymphatic disease, anemia, varicose veins, and potentially heart failure, hypertension, aneurysms, and stroke. These channels appear to be versatile force sensors, used creatively to inform various force-sensing situations. We discuss emergent concepts and controversies and suggest that the potential for new important understanding is substantial

Ptenb Mediates Gastrulation Cell Movements via Cdc42/AKT1 in Zebrafish

Phosphatidylinositol 3-kinase (PI3 kinase) mediates gastrulation cell migration in zebrafish via its regulation of PIP2/PIP3 balance. Although PI3 kinase counter enzyme PTEN has also been reported to be essential for gastrulation, its role in zebrafish gastrulation has been controversial due to the lack of gastrulation defects in pten-null mutants. To clarify this issue, we knocked down a pten isoform, ptenb by using anti-sense morpholino oligos (MOs) in zebrafish embryos and found that ptenb MOs inhibit convergent extension by affecting cell motility and protrusion during gastrulation. The ptenb MO-induced convergence defect could be rescued by a PI3-kinase inhibitor, LY294002 and by overexpressing dominant negative Cdc42. Overexpression of human constitutively active akt1 showed similar convergent extension defects in zebrafish embryos. We also observed a clear enhancement of actin polymerization in ptenb morphants under cofocal microscopy and in actin polymerization assay. These results suggest that Ptenb by antagonizing PI3 kinase and its downstream Akt1 and Cdc42 to regulate actin polymerization that is critical for proper cell motility and migration control during gastrulation in zebrafish

Novel mutations in PIEZO1 cause an autosomal recessive generalized lymphatic dysplasia with non-immune hydrops fetalis.

Generalized lymphatic dysplasia (GLD) is a rare form of primary lymphoedema characterized by a uniform, widespread lymphoedema affecting all segments of the body, with systemic involvement such as intestinal and/or pulmonary lymphangiectasia, pleural effusions, chylothoraces and/or pericardial effusions. This may present prenatally as non-immune hydrops. Here we report homozygous and compound heterozygous mutations in PIEZO1, resulting in an autosomal recessive form of GLD with a high incidence of non-immune hydrops fetalis and childhood onset of facial and four limb lymphoedema. Mutations in PIEZO1, which encodes a mechanically activated ion channel, have been reported with autosomal dominant dehydrated hereditary stomatocytosis and non-immune hydrops of unknown aetiology. Besides its role in red blood cells, our findings indicate that PIEZO1 is also involved in the development of lymphatic structures

Coding Efficiency of Fly Motion Processing Is Set by Firing Rate, Not Firing Precision

To comprehend the principles underlying sensory information processing, it is important to understand how the nervous system deals with various sources of perturbation. Here, we analyze how the representation of motion information in the fly's nervous system changes with temperature and luminance. Although these two environmental variables have a considerable impact on the fly's nervous system, they do not impede the fly to behave suitably over a wide range of conditions. We recorded responses from a motion-sensitive neuron, the H1-cell, to a time-varying stimulus at many different combinations of temperature and luminance. We found that the mean firing rate, but not firing precision, changes with temperature, while both were affected by mean luminance. Because we also found that information rate and coding efficiency are mainly set by the mean firing rate, our results suggest that, in the face of environmental perturbations, the coding efficiency is improved by an increase in the mean firing rate, rather than by an increased firing precision