The infrared signatures of very small grains in the Universe seen by JWST

The near- and mid-IR spectrum of many astronomical objects is dominated by emission bands due to UV-excited polycyclic aromatic hydrocarbons (PAH) and evaporating very small grains (eVSG). Previous studies with the ISO, Spitzer and AKARI space telescopes have shown that the spectral variations of these features are directly related to the local physical conditions that induce a photo-chemical evolution of the band carriers. Because of the limited sensitivity and spatial resolution, these studies have focused mainly on galactic star-forming regions. We discuss how the advent of JWST will allow to extend these studies to previously unresolved sources such as near-by galaxies, and how the analysis of the infrared signatures of PAHs and eVSGs can be used to determine their physical conditions and chemical composition.Comment: To appear in the Proceedings of the annual meeting of the French society of astronomy and astrophysics (SF2A 2015

Impact de l'évolution des hydrocarbures aromatiques polycyliques sur la physique et la chimie des régions des photodissociation : une étude dans l'infrarouge et le millimétrique

Les molécules Polycycliques Aromatiques Hydrogénées (PAH) sont un constituant majeur de la matière interstellaire, contenant environ 20% de la totalité du carbone dans notre galaxie. Les PAH jouent un rôle majeur dans la physique et la chimie des régions de photo-dissociation (PDR). Dans ces environnements, l'évolution des PAH est pilotée par le champ de rayonnement ultraviolet (UV) et il a été proposé qu'elle soit liée à celle des très petites particules de poussière et aux petits hydrocarbures. Dans ce travail, nous proposons un nouvel éclairage sur ces scénarios d'évolution en combinant les analyses des données infrarouges (IR) des télescopes spatiaux ISO, Spitzer et AKARI, à de nouvelles observations dans les domaines de l'IR lointain et du sub-millimétrique obtenues par le satellite Herschel ainsi que dans le domaine millimétrique grâce aux télescopes au sol de l'IRAM. Nous avons développé une nouvelle méthode d'analyse des observations de spectro-imagerie de l'IR moyen qui permet d'étudier l'évolution des très petits grains en cours d'évaporation (eVSG) dans les PDR. Cette procédure fournit une estimation de la fraction de carbone contenu dans les eVSG par rapport au total du carbone contenu dans les espèces responsables de l'émission des Bandes Infrarouges Aromatiques (AIB). Cette quantité s'avère être reliée au champ de rayonnement UV et peut ainsi être utilisée comme sonde de l'intensité de ce rayonnement dans des sources résolues ou non spatialement. Les résultats obtenus sont également cohérents avec un scénario dans lequel la destruction des eVSG par le champ UV donne naissance à des PAH libres. Les résultats de l'analyse dans l'IR moyen sont comparés aux observations des domaines du proche IR et du millimétrique, montrant que les processus de destruction des eVSG pourraient être une source de petits hydrocarbures. Une modélisation précise de la chimie des hydrocarbures dans les PDR s'avère nécessaire pour quantifier ce scénario. Nous avons utilisé le télescope de 30m de l'IRAM pour chercher la signature rotationnelle spécifique d'un PAH individuel, le corannulène, dans le spectre millimétrique de la nébuleuse du Rectangle Rouge. En comparant à des modèles la limite supérieure d'abondance déduite de la non détection de ce PAH, nous avons pu contraindre l'abondance maximale des PAH de petite taille dans cette source. Ceci indique que ces espèces sont sous-abondantes dans les enveloppes des étoiles carbonées évoluées, et contraint les mécanismes de formation des PAH dans ces environnements. Les résultats de l'analyse dans l'infrarouge moyen sont combinés aux observations de plusieurs constituants du gaz dans l'IR lointain et le submillimétrique grâce au satellite Herschel et dans le millimétrique avec les instruments de l'IRAM afin d'étudier la géométrie, le bilan énergétique et la dynamique des PDR associées à la nébuleuse par réflexion NGC~7023. Ce sujet devrait continuer à progresser dans les années à venir grâce à de nouvelles données Herschel, mais aussi l'arrivée de futures missions spatiales JWST et SPICA et de l'interféromètre ALMA.Polycyclic Aromatic Hydrocarbons (PAHs) are a major constituent of interstellar matter, containing about 20% of the total carbon in our Galaxy. PAHs are known to play a major role in the chemistry and the physics of photo-dissociation regions (PDRs). In these environments, the evolution of PAHs is driven by the UV field and it has been proposed to be linked to that of very small dust particles and small molecular hydrocarbons. In this work, we provide further insights into these evolutionary scenarios by combining the analysis of infrared (IR) data from ISO, Spitzer and AKARI space telescopes with new observations in the far-IR and sub-mm domains obtained with Herschel as well as in the millimeter domain using the IRAM ground-based telescopes. We have developed a new analysis method for the mid-IR spectro-imagery observations that allows to study the photo-processing of evaporating Very Small Grains (eVSGs) in PDRs. This procedure provides an estimate of the fraction of carbon locked in eVSGs compared to all atoms in the AIB carriers. This quantity is found to be related to the UV radiation field and can therefore be used as a tracer of its intensity in both resolved and unresolved sources. The obtained results are also consistent with a scenario in which eVSGs are destroyed by the UV field, giving birth to free PAHs. The results of the mid-IR analysis are compared with near-IR and millimeter observations, showing that the destruction process of eVSGs may be a source of production of small hydrocarbons. An accurate modelling of hydrocarbon chemistry in PDRs is needed to quantitatively test this scenario. We used the IRAM 30m telescope to search for the specific rotational signatures of an individual PAH, corannulene, in the millimeter spectrum of the Red Rectangle nebula. The comparison of the derived upper limit for detection with models allows to constrain the maximum abundance of small PAHs in this source. This provides evidence that these small species are under-abundant in the envelopes of evolved carbon stars and constrains the formation mechanisms of PAHs in these environments. The results of the mid-IR analysis are combined with observations of several gas species in the far-IR and sub-millimeter with Herschel and in the millimeter with IRAM to study the geometry, energetics, and dynamics of the PDRs in the reflection nebula NGC~7023. Further progresses on this topics await for more Herschel data but also for the forthcoming JWST and SPICA space missions and the ALMA interferometer

Blind decomposition of Herschel-HIFI spectral maps of the NGC 7023 nebula

Large spatial-spectral surveys are more and more common in astronomy. This calls for the need of new methods to analyze such mega- to giga-pixel data-cubes. In this paper we present a method to decompose such observations into a limited and comprehensive set of components. The original data can then be interpreted in terms of linear combinations of these components. The method uses non-negative matrix factorization (NMF) to extract latent spectral end-members in the data. The number of needed end-members is estimated based on the level of noise in the data. A Monte-Carlo scheme is adopted to estimate the optimal end-members, and their standard deviations. Finally, the maps of linear coefficients are reconstructed using non-negative least squares. We apply this method to a set of hyperspectral data of the NGC 7023 nebula, obtained recently with the HIFI instrument onboard the Herschel space observatory, and provide a first interpretation of the results in terms of 3-dimensional dynamical structure of the region.Comment: Proceedings of the 2012 meeting of the french astronomical society (SF2A) in Nic

Distinctive HLA-II association with primary biliary cholangitis on the Island of Sardinia

Background: The HLA DRB1*08 allele associated with primary biliary cholangitis (PBC) among Caucasians is of low frequency in the Sardinian population. Objective: The aim of our study was to type a cohort of PBC patients from the island of Sardinia for HLA class II antigens. Methods: Twenty Sardinian patients affected by PBC, 14 with autoimmune hepatitis (AIH) and 89 healthy controls (HCs) were typed for HLA class II alleles by dot-blot analysis. Results: The PBC-associated HLA DRB1*08 allele was detected in none of the studied individuals. The DRB1*0301–DQB1*0201 was the prevalent HLA haplotype, detected in 19 (47.5%) out of 40 PBC haplotypes (OR = 3.0; 95% CI 1.5–6.2) and in 11 (39.3%) out of 28 AIH haplotypes (OR = 2.2; 95% CI 0.94–5.0), but in only 41 (23%) out of 178 HC haplotypes. Moreover, PBC patients showed an increased frequency of homozygosity for the DQB1*0201 allele (35% compared with 6.7% of the HCs; OR = 7.5; 95% CI 2.2–25.7). The frequency of the DRB1*11 allele in the PBC group was about half of that seen in the Sardinian HCs (7.5% vs 15.7%) (p = ns). Conclusions: Our study confirmed the low frequency of the HLA DRB1*08 allele among Sardinians, either in the general population or PBC patients. The high prevalence of the HLA DRB1*0301–DQB1*0201 haplotype is a distinctive genetic feature of PBC among Sardinians. Our study strengthens the hypothesis that still unknown genetic, epigenetic, and environmental factors must be involved in the pathogenesis of different HLA-associated liver diseases, and it represents a pathfinder that warrants exploration in a future extensive study

Observations of Rocks in Jezero Landing Site: SuperCam/LIBS technique overview of results from the first six months of operations.

On-board the Perseverance rover, the SuperCam instrument is being used as a remote-sensing facility to analyze rocks and soils targets. SuperCam is a suite of five coaligned techniques: just like ChemCam (onboard MSL/Curiosity rover on Mars since 2012), it uses the Laser Induced Breakdown Spectroscopy (LIBS) technique to determine the elementary composition of the targets, but it also uses Raman (for the first time in planetary science) and visible-infrared (VISIR - for the first time in situ) spectroscopic methods in order to access some mineralogical and structural information. A microphone gives access to some physical parameters of the sampled rocks (such as hardness) as well as to some atmospheric parameters (wind direction). These chemical and mineralogical analyses are contextualized thanks to a color remote micro-imager (RMI). In this study, we focus mainly on the LIBS results obtained so far

The SuperCam Instrument Suite on the Mars 2020 Rover: Science Objectives and Mast-Unit Description

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds

Impact de l'évolution des hydrocarbures aromatiques polycyliques sur la physique et la chimie des régions des photodissociation (une étude dans l'infrarouge et le millimétrique)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

TT virus infection in Italy: prevalence and genotypes in healthy subjects, viral liver diseases and asymptomatic infections by parenterally transmitted viruses

This study was aimed to evaluate TT virus prevalence in subjects with hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections in patients affected by hepatitis of unknown origin (non-A-non-E hepatitis) and in healthy subjects who had not been exposed to HBV, HCV and HIV. A total of 317 subjects were tested; 40 were HBsAg asymptomatic carriers, 57 subjects were anti-HCV positive (45 without chronic hepatitis and 12 with HCV-related chronic hepatitis), and 27 had chronic non-A-non-E hepatitis. Fifty-seven subjects were intravenous drug users (IVDUs) (52 with HCV or/and EHV infections), seven patients underwent a liver transplant for fulminant hepatitis and 137 were healthy subjects from the general population. Overall, TTV-DNA was detected in 62 subjects (19.6%): in 17.9% of the HBsAg carriers, in 14% of the anti-HCV-positive patients (in 8.3% and in 15.5% of patients with and without chronic hepatitis, respectively), in 22.2% of non-A-non-E hepatitis patients, in 22.8% of IVDUs, in 57.1% of fulminant hepatitis patients. TTV-DNA was also found in 20.4% healthy subjects. The prevalence in the different subgroups was not statistically different. The genotypes were identified in 40 of the 62 (64.5%) TTV-DNA positive samples: genotype la in 17.5%, lb in 27.5%, genotype 2 in 27.5%, genotype 3 in 15.0%, genotype 4 in 5.0% and genotype 5 in 7.5%; the genotype distribution in the subsets of patients was not significantly different. In conclusion, this study showed that TTV infection is common in Italy; it is widespread throughout the entire population and five genotypes are present in Sardinia. Our results further dismiss the role of TTV as cofactor in influencing the clinical course of infections with other hepatitis viruses as well as the role of HIV in enhancing TTV transmission and replication

Advanced Parkinson’s disease treatment patterns in Italy: an observational study interim analysis

AbstractBackground Oral levodopa remains the mainstay of treatment for Parkinson’s disease (PD). However, as PD progresses, response to treatment may fluctuate. Managing fluctuations can be demanding for clinicians and patients. There is a paucity of real-world studies reporting on PD management in patients with fluctuations in treatment response, especially in patients with advanced stages of PD. The multicentre, observational Parkinson’s Disease Fluctuations treatment PAthway (PD-FPA) study describes the real-life management of response fluctuations in Italian patients with advanced PD.Patients and Methods PD-FPA had a retrospective and prospective phase; herein, retrospective results are presented. Ten Italian centres enrolled patients with a PD diagnosis from 10–15 years prior to study entry (T0) and who had ≥2-year history of fluctuations. Data on patient demographics, medical history, PD stage, fluctuation characteristics, symptoms, and prescribed treatments were collected at T0 and retrospectively (2 years prior to T0) via patient chart review/interview.Results Overall, 296 patients (60% male, mean age 68 years, 84% with Hoehn and Yahr scores 2–3) were enrolled. At T0, most patients (99.3%) were on oral levodopa therapy. All patients used dopaminergic medications; adjunctive medications included dopamine agonists (56%) and monoamine oxidase B (60%) and catechol-O-methyltransferase enzyme inhibitors (41%). At T0, 51% of patients had changed therapy, with response fluctuations being the most common reason (74%); wearing-off was the most common fluctuation (83%).Conclusion This interim analysis of PD-FPA suggests that adequate levodopa dosing and adjunctive medications can stabilize advanced PD and provide patients with a good quality of life