Simultaneous multi-band detection of Low Surface Brightness galaxies with Markovian modelling

We present an algorithm for the detection of Low Surface Brightness (LSB) galaxies in images, called MARSIAA (MARkovian Software for Image Analysis in Astronomy), which is based on multi-scale Markovian modeling. MARSIAA can be applied simultaneously to different bands. It segments an image into a user-defined number of classes, according to their surface brightness and surroundings - typically, one or two classes contain the LSB structures. We have developed an algorithm, called DetectLSB, which allows the efficient identification of LSB galaxies from among the candidate sources selected by MARSIAA. To assess the robustness of our method, the method was applied to a set of 18 B and I band images (covering 1.3 square degrees in total) of the Virgo cluster. To further assess the completeness of the results of our method, both MARSIAA, SExtractor, and DetectLSB were applied to search for (i) mock Virgo LSB galaxies inserted into a set of deep Next Generation Virgo Survey (NGVS) gri-band subimages and (ii) Virgo LSB galaxies identified by eye in a full set of NGVS square degree gri images. MARSIAA/DetectLSB recovered ~20% more mock LSB galaxies and ~40% more LSB galaxies identified by eye than SExtractor/DetectLSB. With a 90% fraction of false positives from an entirely unsupervised pipeline, a completeness of 90% is reached for sources with r_e > 3" at a mean surface brightness level of mu_g=27.7 mag/arcsec^2 and a central surface brightness of mu^0 g=26.7 mag/arcsec^2. About 10% of the false positives are artifacts, the rest being background galaxies. We have found our method to be complementary to the application of matched filters and an optimized use of SExtractor, and to have the following advantages: it is scale-free, can be applied simultaneously to several bands, and is well adapted for crowded regions on the sky.Comment: 39 pages, 18 figures, accepted for publication in A

Color display for multiwavelength astronomical images

This paper proposes a new approach for the color display of multispectral/hyperspectral images. The color representation of such data becomes problematic when the number of bands is higher than three, i.e. the basic RGB (Red, Green, Blue) representation is not straightforward. Here we employ a technique that uses a segmentation map, like an a priori information, and then compute a Factorial Discriminant Analysis (Fischer analysis) in order to allow, at best, a distribution of the information in the color space HSV (Hue, Saturation, Value). The information collected from the segmentation map (where each pixel is associated with class) has been shown to be advantages in the representation of the images through the results obtained on increasing size image collections in the framework of astronomical images. This method can easily be applied to other domains such as polarimetric or remote sensing imagery.Cet article propose une nouvelle méthode de représentation et de visualisation en couleur d'images multispectrales ou hyperspectrales. Le problème de la visualisation de telles données est en effet problématique dès que le nombre de bandes spectrales est supérieur à trois, i.e., la représentation triviale RVB (Rouge, Vert, Bleu) n'est plus directe. Le principe consiste ici à utiliser une carte de segmentation préalablement obtenue, a priori, et à réaliser une analyse factorielle discriminante permettant de distribuer au mieux l'information dans l'espace des couleurs TSL (Teinte, Saturation, Luminance). L'information apportée par la carte de segmentation (chaque site est associé à une classe) peut se révéler judicieuse comme le montrent les résultats obtenus sur des lots d'images de tailles croissantes dans le cadre de l'imagerie astronomique. Cette méthode est générale et s'applique également à d'autres domaines manipulant des images multicomposantes ou multivariées comme en télédétection ou en imagerie polarimétrique

Beneficial insects in agricultural landscapes: faunal, ecological and functional contributions of recent studies in the canton of Geneva (Switzerland)

Description of the subject. In the context of biodiversity maintenance in agricultural environments and of risk reduction related to the use of phytosanitary products, it seems essential to improve our knowledge of the beneficial insects that develop in these ecosystems.Objectives. This article reviews the state of knowledge regarding insect auxiliaries and highlights the main faunal, ecological and functional contributions from recent studies carried out in an agricultural context in Geneva.Method. Data were collected from 2014 to 2019 on several families of predatory and pollinating auxiliaries in various agricultural contexts (extensive grasslands, vineyards, orchards, rapeseed crops, vegetable crops) using Barber, Malaise and emergence traps.Results. 48,921 individual records were collected belonging to 477 species of the main families of auxiliaries. Of these, four species were observed for the first time in Switzerland and 50 in the canton of Geneva. 357 (+/- 75%) of the species had a predatory stage and 103 (+/- 22%) could be regarded as valuable crop auxiliaries. The use of emergence traps made it possible to attest that at least a third of the species, including some rare or threatened species, are able to successfully carry out their life cycles within agricultural environments or to use them as overwintering sites.Conclusions. This review increases our understanding of the composition of the biodiversity of agricultural environments, which constitutes a significant component of biodiversity in Switzerland and in neighboring countries. It also highlights the role of semi-natural habitats as extensive grasslands or inter-rows of vineyards in supporting the development of many rare and sometimes threatened species

Low-temperature thin-film indium bonding for reliable wafer-level hermetic MEMS packaging

This paper reports on low-temperature and hermetic thin-film indium bonding for wafer-level encapsulation and packaging of delicate and temperature sensitive devices. This indium-bonding technology enables bonding of surface materials commonly used in MEMS technology. The temperature is kept below 140 degrees C for all process steps and no surface treatment is applied before and during bonding. This bonding technology allows hermetic sealing at 140 degrees C with a leak rate below 4 x 10(-12) mbar l s(-1) at room temperature. The tensile strength of the bonds up to 25 MPa goes along with a very high yield

Micro-fabricated alkali vapor cells sealed at low temperatures with thin-film metallic bonding

We report on the characterization of micro-fabricated alkali vapor cells, sealed by low-temperature thin-film metallic bonding. The low sealing temperatures ≤ 140°C are of high interest in view of future micro-fabricated cells using anti-relaxation wall coatings. Long-term measurements using saturated-absorption and double-resonance spectroscopy show a stable pressure inside the cells and therefore an excellent hermeticity of the bonding over several months. This is also confirmed by independent leak-rate measurements of indium bonded sample cells by a membrane deflection method

Low-temperature indium hermetic sealing of alkali vapor-cells for chip-scale atomic clocks

We present a low-temperature indium hermetic bonding technique on wafer level without using flux, active atmosphere or other pretreatment of the indium. Its simplicity and low temperatures allow encapsulation of sensitive MEMS devices. Bonding stronger than 18 MPa was accomplished with temperatures never exceeding 140 degrees C. Leak rate measurements revealed leak rate below 2.5 x 10(-12) atm cc/s. This bonding technique is then applied to fabricate rubidium vapor-cells for chip-scale atomic clocks (CSAC). Saturated absorption spectroscopy performed two and five months after fabrication confirms less than 1 mbar of gas contamination, and the retrieved clock signal demonstrates the suitability of the cell for clock applications

TCR sequencing and cloning methods for repertoire analysis and isolation of tumor-reactive TCRs.

T cell receptor (TCR) technologies, including repertoire analyses and T cell engineering, are increasingly important in the clinical management of cellular immunity in cancer, transplantation, and other immune diseases. However, sensitive and reliable methods for repertoire analyses and TCR cloning are still lacking. Here, we report on SEQTR, a high-throughput approach to analyze human and mouse repertoires that is more sensitive, reproducible, and accurate as compared with commonly used assays, and thus more reliably captures the complexity of blood and tumor TCR repertoires. We also present a TCR cloning strategy to specifically amplify TCRs from T cell populations. Positioned downstream of single-cell or bulk TCR sequencing, it allows time- and cost-effective discovery, cloning, screening, and engineering of tumor-specific TCRs. Together, these methods will accelerate TCR repertoire analyses in discovery, translational, and clinical settings and permit fast TCR engineering for cellular therapies

High density lipoproteins and ischemia reperfusion injury: the therapeutic potential of HDL to modulate cell survival pathways

The clinical importance of high density lipoproteins has grown in recent years with demonstrations of their impact on diverse pathological mechanisms implicated not only in vascular disease, but also in other physiological systems. This is related to the multiple functions associated with high-density lipoproteins (HDL), notably their ability to limit oxidant and inflammatory processes, which are common to different disease states. A second feature of particular clinical relevance is the possibility of synthesising a simplified form of HDL that exhibits some of the functions of the mature lipoprotein. The therapeutic potential of synthetic HDL is already under clinical scrutiny. To illustrate these points, the present chapter will discuss the role of HDL in limiting damage to the heart consequent to myocardial ischemia. It will review molecular survival pathways stimulated by HDL to combat oxidative stress and the potential of synthetic HDL to activate such pathways