First in-situ detection of the CN radical in comets and evidence for a distributed source

Although the debate regarding the origin of the cyano (CN) radical in comets has been ongoing for many decades, it has yielded no definitive answer to date. CN could previously only be studied remotely, strongly hampering efforts to constrain its origin because of very limited spatial information. Thanks to the European Space Agency's Rosetta spacecraft, which orbited comet 67P/Churyumov-Gerasimenko for two years, we can investigate, for the first time, CN around a comet at high spatial and temporal resolution. On board Rosetta's orbiter module, the high-resolution double-focusing mass spectrometer DFMS, part of the ROSINA instrument suite, analyzed the neutral volatiles (including HCN and the CN radical) in the inner coma of the comet throughout that whole two-year phase and at variable cometocentric distances. From a thorough analysis of the full-mission data, the abundance of CN radicals in the cometary coma has been derived. Data from a close flyby event in February 2015 indicate a distributed origin for the CN radical in comet 67P/Churyumov-Gerasimenko.Comment: Accepted for publication in MNRA

Obstacles and resources of educational upward transition - a qualitative study with young adults from families with low socioeconomic background and/or migration background

Junge Menschen aus sozial benachteiligten Familien mit oder ohne Migrationshintergrund werden mit ungleichen Bildungsgelegenheiten auf dem Weg in die tertiäre Bildung konfrontiert. Diese Studie analysiert Hindernisse, die aus Bildungsnachteilen resultieren können, und Ressourcen, die zu Bildungserfolg führen können. Die Studie basiert auf der qualitativen Inhaltsanalyse von Interviews mit Bildungsaufsteigern und -aufsteigerinnen aus benachteiligten Milieus. Zusammenfassend zeigen die Ergebnisse, dass gute Beziehungen und soziale Unterstützung durch Eltern, Lehrpersonen sowie Mitschülerinnen und Mitschüler die Chance auf einen Bildungsaufstieg sowohl von einheimischen als auch von Personen mit Migrationshintergrund aus benachteiligten Milieus wesentlich begünstigen. (DIPF/Orig.)Young people from socially biased and / or immigrant families are confronted with unequal educational opportunities on the way to the tertiary education segment. The present study analyzes barriers that can arise from educational disadvantage and resources that can be conducive to educational success. The study is based on the structured qualitative content analysis of interviews with adults with disadvantaged backgrounds. In summary, the results show that good relationships and social support from parents, teachers and classmates are important resources that greatly enhance the opportunity for educational success of both native and migrant youth. (DIPF/Orig.

Detection of volatiles undergoing sublimation from 67P/Churyumov-Gerasimenko coma particles using ROSINA/COPS. I. The ram gauge

The ESA Rosetta mission has allowed an extensive in-situ study of comet 67P/Churyumov-Gerasimenko. In measurements performed by the ram gauge of the on-board COmet Pressure Sensor (COPS), features have been observed that deviate from the nominal ram gauge signal. These are attributable to the sublimation of the volatile fraction of cometary icy particles containing volatiles and refractories. The objective of this work is the investigation of the volatile content of icy particles that entered the COPS ram gauge. The ram gauge measurements are inspected for features that we associate to the sublimation of the volatile component of cometary particles impacting the instrument. All sublimation features with high enough signal to noise ratio are modelled by fitting one or more exponential decay functions. The parameters of these fits are used to categorise different compositions of the sublimating component. From features attributable to ice sublimation, we infer the detection of 73 icy particles containing volatiles. 25 detections have enough volatile content for an in-depth study. From the values of the exponential decay constants, we classified the 25 inferred icy particles into three types, interpreted as different volatile compositions, possibly further complicated by different morphologies. Available data do not give indication as to which molecules compose the different types. Nevertheless, we can estimate the total volume of volatiles, expressed as the diameter of an equivalent sphere of water (density of 1 g cm$^{-3}$). This was found to be on the order of hundreds of nanometres.Comment: 9 pages, 8 figures, 2 tables, published in A&A, figures with better resolutio

Detection of volatiles undergoing sublimation from 67P/Churyumov-Gerasimenko coma particles using ROSINA/COPS. II. The nude gauge

In an earlier study, we reported that the ram gauge of the COmet Pressure Sensor (COPS), one of the three instruments of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), could be used to obtain information about the sublimating content of icy particles, made up of volatiles and conceivably refractories coming from comet 67P/Churyumov-Gerasimenko. In this work, we extend the investigation to the second COPS gauge, the nude gauge. In particular, we analyse the volume of the volatile content of coma particles, along with a search for possible dependencies between the nude gauge detection rate (i.e. the rate at which icy particles are detected by the nude gauge) and the position of the Rosetta spacecraft. We also investigate the correlations of the nude gauge detection rate with the quantities associated with cometary activity. Although it was not originally designed for such a purpose, the COPS nude gauge has been able to detect $\sim$67000 features generated by the sublimation of the volatile content of icy particles. The nude gauge detection rate follows a trend that is inversely proportional to the heliocentric distance. This result is interpreted as a confirmation of a possible relation between the nude gauge detection rate and cometary activity. Thus, we compared the former with parameters related to cometary activity and obtained significant correlations, indicating that the frequency of icy particle detection is driven by cometary activity. Furthermore, by representing the volatile part of the icy particles as equivalent spheres with a density of 1 g cm$^{-3}$, we obtained a range of diameters between 60 and 793 nanometres, with the smaller ones ($<390\,\mathrm{nm}$ in diameter) having a size distribution power index of $-4.79\pm 0.26$.Comment: 12 pages, 10 figures, accepted for publication in A&

Barriere e risorse per l'avanzamento scolastico - Uno studio qualitativo con giovani adulti di basso status socioeconomico e/o con un background di migrazione

Junge Menschen aus sozial benachteiligten Familien mit oder ohne Migrationshintergrund werden mit ungleichen Bildungsgelegenheiten auf dem Weg in die tertiäre Bildung konfrontiert. Diese Studie analysiert Hindernisse, die aus Bildungsnachteilen resultieren können, und Ressourcen, die zu Bildungserfolg führen können. Die Studie basiert auf der qualitativen Inhaltsanalyse von Interviews mit Bildungsaufsteigern und -aufsteigerinnen aus benachteiligten Milieus. Zusammenfassend zeigen die Ergebnisse, dass gute Beziehungen und soziale Unterstützung durch Eltern, Lehrpersonen sowie Mitschülerinnen und Mitschüler die Chance auf einen Bildungsaufstieg sowohl von einheimischen als auch von Personen mit Migrationshintergrund aus benachteiligten Milieus wesentlich begünstigen.Young people from socially biased and / or immigrant families are confronted with unequal educational opportunities on the way to the tertiary education segment. The present study analyzes barriers that can arise from educational disadvantage and resources that can be conducive to educational success. The study is based on the structured qualitative content analysis of interviews with adults with disadvantaged backgrounds. In summary, the results show that good relationships and social support from parents, teachers and classmates are important resources that greatly enhance the opportunity for educational success of both native and migrant youth.Les jeunes des familles socialement défavorisées, qu'ils soient ou non de l'immigration, sont confrontés à l'inégalité des opportunités éducatives sur le chemin de l'enseignement supérieur. Cette étude analyse les obstacles qui peuvent résulter de désavantages éducatifs et les ressources qui peuvent mener à la réussite éducative. L'étude est basée sur l'analyse de contenu qualitative d'entretiens avec des personnes en ascension scolaire issues de milieux défavorisés. En résumé, les résultats montrent que de bonnes relations et un soutien social de la part des parents, des enseignant·e·s et des camarades de classe favorisent considérablement les chances d'ascension scolaire, tant pour les autochtones que pour les personnes issues de l'immigration de milieux défavorisés.I giovani provenienti da famiglie socialmente svantaggiate, con o senza un background migratorio, si confrontano con opportunità educative ineguali sulla via dell'istruzione terziaria. Questo studio analizza gli ostacoli che possono derivare dagli svantaggi educativi e le risorse che possono portare al successo educativo. Lo studio si basa sull'analisi qualitativa del contenuto di interviste con persone provenienti da ambienti svantaggiati che hanno ottenuto dei successi scolastici. In sintesi, i risultati mostrano che le buone relazioni e il sostegno sociale da parte di genitori, insegnanti e compagni di classe sono risorse importanti che favoriscono significativamente la possibilità di avanzamento scolastico sia per i nativi che per i migranti provenienti da ambienti svantaggiati

[Dens invaginatus. Review of the literature and diagnostic and therapeutic guidelines]

Dens invaginatus is a clinically relevant malformation of teeth resulting from an infolding of enamel and dentine into the dental structure during tooth formation, hence the former denomination "dens in dente". The dens invaginatus shows multiple morphological variations of crown and root formation. This frequently leads to caries, pulpal and periodontal involvement with necrosis and loss of attachment. Therefore, early diagnosis and prevention are of utmost importance. Due to the complexity of the malformation, treatment options in former days were limited. This article presents a profound review of the literature regarding etiology, epidemiology and histology. It discusses clinical appearance and diagnosis and it provides guidelines for decision-making and treatment of invaginated teeth

Ammonium Salts as a Source of Small Molecules Observed with High-Resolution Electron-Impact Ionization Mass Spectrometry

Recent high-resolution in situ mass spectrometry at comet 67P/Churyumov−Gerasimenko visited by European Space Agency’s Rosetta spacecraft raised the question, if sublimating ammonium salts can unequivocally be detected in the cometary coma. In laboratory experiments with the twin model of the space instrument, two prototypic ammonium salts NH4B, namely, ammonium chloride (B = Cl−) and ammonium formate (B = HCOO−) (as well as methodologically relevant isotopologues), were allowed to sublimate in vacuum while mass spectra were collected. High-resolution electronimpact ionization mass spectrometry provides an outstanding experimental tool to investigate the complex physicochemical processes occurring during the sublimation of ammonium salts. Sublimation of ammonium chloride led to the observation of the ammonium cation NH4 + and the chloramide molecule NH2Cl in the neutral gas mode of the instrument. These observations could be jointly interpreted as indirect evidence for the existence of a neutral gaseous parent species (either as the molecular complex NH3···HB or the double-ionic species NH4 +···B−). However, the qualitative fragmentation pattern we present for 13C15N-ammonium formate suggests an alternative route of NH4 + production within the ionization region of the instrument, namely, by protonation/hydrogenation. Besides NH4 +, other species were observed that were formed in protonation/hydrogenation reactions. Moreover, together with the two major species from the decomposition of the salt, ammonia and formic acid, three minor species also contributed to the fragmentation pattern: HCN/HNC, HOCN/HNCO, and CH3NO. Like chloramide, formamide (CH3NO) also is a secondary species probably formed in a pseudo-intramolecular chemical reaction while ammonia and the respective acid are in a state of association. HCN/HNC and HOCN/HNCO are ternary products coming out of formamide decomposition reactions. We discuss our experimental findings, summarized in a tentative chemical reaction network, in light of the available theoretical literature and highlight their relevance for the interpretation of in situ measurements in space research. 1

CHO-Bearing Molecules in Comet 67P/Churyumov-Gerasimenko

In 2004, the Rosetta spacecraft was sent to comet 67P/Churyumov-Gerasimenko for the first ever long-term investigation of a comet. After its arrival in 2014, the spacecraft spent more than 2 years in immediate proximity to the comet. During these 2 years, the ROSINA Double Focusing Mass Spectrometer (DFMS) onboard Rosetta discovered a coma with an unexpectedly complex chemical composition that included many oxygenated molecules. Determining the exact cometary composition is an essential first step to understanding of the organic rich chemistry in star forming regions and protoplanetary disks that are ultimately conserved in cometary ices. In this study, a joint approach of laboratory calibration and space data analysis was used to perform a detailed identification and quantification of CHO compounds in the coma of 67P/Churyumov-Gerasimenko. The goal was to derive the CHO compound abundances relative to water for masses up to 100 u. For this study, the May 2015 postequinox period represents the best bulk abundances of comet 67P/Churyumov-Gerasimenko. A wide variety of CHO compounds were discovered, and their bulk abundances were derived. Finally, these results are compared to abundances of CHO-bearing molecules in other comets, obtained mostly from ground-based observations and modeling