Evolving R Coronae Borealis Stars with MESA

The R Coronae Borealis (RCB) stars are rare hydrogen--deficient, carbon--rich supergiants. They undergo extreme, irregular declines in brightness of many magnitudes due to the formation of thick clouds of carbon dust. It is thought that RCB stars result from the mergers of CO/He white dwarf (WD) binaries. We constructed post--merger spherically asymmetric models computed with the MESA code, and then followed the evolution into the region of the HR diagram where the RCB stars are located. We also investigated nucleosynthesis in the dynamically accreting material of CO/He WD mergers which may provide a suitable environment for significant production of 18O and the very low 16O/18O values observed. We have also discovered that the N abundance depends sensitively on the peak temperature in the He--burning shell. Our MESA modeling consists of engineering the star by adding He--WD material to an initial CO--WD model, and then following the post--merger evolution using a nuclear--reaction network to match the observed RCB abundances as it expands and cools to become an RCB star. These new models are more physical because they include rotation, mixing, mass-loss, and nucleosynthesis within MESA. We follow the later evolution beyond the RCB phase to determine the stars' likely lifetimes. The relative numbers of known RCB and Extreme Helium (EHe) stars correspond well to the lifetimes predicted from the MESA models. In addition, most of computed abundances agree very well with the observed range of abundances for the RCB class.Comment: 14 pages, 7 figures, MNRAS in pres

Developmental malformations of human tongue and associated syndromes (review)

The development of the tongue begins as known, in the floor of the primitive oral cavity, when the human embryo is four weeks old.More specifically, the tongue develops from the region of the first three or four branchial arches during the period that the external face develops. Malformations of the tongue, are structural defects, present at birth and happening during embryogenesis. The most common malformations are:1. Aglossia2. Microglossia, which is always combined with other defects and syndromes, like Moëbius syndrome3. Macroglossia, which is commonly associated with cretinism, Down’s syndrome, Hunter’s syndrome, Sanfilippo syndrome and other types of mental retardation4. Accesory tongue5. Long tongue6. Cleft or Bifid tongue, condition very usual in patients with the orodigitofacial syndrome7. Glossitis Rhombica Mediana, a developmental malformation?8. Lingual thyroid.Malformations are extensively analysed and discussed.Le développement de la langue commence au niveau du plancher de la cavité orale primitive lorsque l’embryon humain est âgé de 4 semaines.Plus précisément, la langue se développe dans la région des trois ou quatre premiers arcs branchiaux durant la période du développement de la face externe. Les malformations de la langue correspondent à des défauts de structure présents à la naissance et survenant au cours de l’embryogenèse. Les malformations les plus communes sont:1. Aglossie2. Microglossie, qui est souvent combinée à d’autres anomalies ou syndromes, tel le syndrome de Moebius3. Macroglossie, qui est communément associée au crétinisme, au syndrome de Down, au syndrome de Hunter, au syndrome de Sanfilippo et à d’autres types de retard mental4. Langue accessoire5. Langue longue6. Langue bifide, condition très usuelle chez des patients présentant le syndrome orodigitofacial7. Glossite rhomboïde médiane (?)8. Thyroïde linguale.Les malformations sont analysées et discutées

A chemical imaging and Nano-ARPES study of well-ordered thermally reduced SrTiO3(100)

The structural and electronic properties of thermally reduced SrTiO3(100) single crystals have been investigated using a probe with real- and reciprocal-space sensitivity: a synchrotron radiation microsopic setup which offers the possibility of Scanning Photoemission Microscopy and Angle Resolved Photoelectron Spectroscopy (ARPES) down to the nanometric scale. We have spectroscopically imaged the chemical composition of samples which present reproducible and suitable low-energy electron diffraction patterns after following well-established thermal reduction protocols. At the micrometric scale, Ca-rich areas have been directly imaged using high-energy resolution core level photoemission. Moreover, we have monitored the effect of Ca segregation on different features of the SrTiO3(100) electronic band structure, measuring ARPES inside, outside and at the interface of surface inhomogeneities with the identified Ca-rich areas. In particular, the interaction of Ca with the well-known intragap localized state, previously attributed to oxygen vacancies, has been investigated. Moreover, the combination of direct imaging and spectroscopic techniques with high spatial resolution has clarified the long-standing dilemma related to the bulk or surface character of Ca segregation in SrTiO3. Our results present solid evidence that the penetration depth of Ca segregation is very small. In contrast to what has been previously proposed, the origin of long-range surface reconstructions can unlikely be associated to Ca due to strong local variations of its surface concentration.Comment: 7 pages, 6 figure

Mechanochemical Synthesis of N-Aryl Amides from O-Protected Hydroxamic Acids

Two robust and efficient mechanochemical protocols for the synthesis of an array of N-arylamides have been developed. This was achieved by a C-N cross-coupling between O-pivaloyl hydroxamic acids and aryl iodides or aryl boronic acids, in the presence of a stoichiometric amount of a copper mediator. The effectiveness of this method is highlighted by the high-yielding (up to 94%), scalable (up to 8 mmol), and rapid (20 minutes) synthesis of N-aryl amides (15 examples), using a variety of deactivated and sterically encumbered substrates, whilst employing mild conditions and in the absence of solvents. In addition, it was determined that whilst the O-pivaloyl hydroxamic acid precursors can be synthesised mechanochemically, iron contamination originating from the steel jars was found to occur which can hinder the efficacy of this process. Furthermore, 3D printing was used to produce custom milling jars that could successfully accommodate a scaled-up version of the two protocols

DoctorEye: A clinically driven multifunctional platform, for accurate processing of tumors in medical images

Copyright @ Skounakis et al.This paper presents a novel, open access interactive platform for 3D medical image analysis, simulation and visualization, focusing in oncology images. The platform was developed through constant interaction and feedback from expert clinicians integrating a thorough analysis of their requirements while having an ultimate goal of assisting in accurately delineating tumors. It allows clinicians not only to work with a large number of 3D tomographic datasets but also to efficiently annotate multiple regions of interest in the same session. Manual and semi-automatic segmentation techniques combined with integrated correction tools assist in the quick and refined delineation of tumors while different users can add different components related to oncology such as tumor growth and simulation algorithms for improving therapy planning. The platform has been tested by different users and over large number of heterogeneous tomographic datasets to ensure stability, usability, extensibility and robustness with promising results. AVAILABILITY: THE PLATFORM, A MANUAL AND TUTORIAL VIDEOS ARE AVAILABLE AT: http://biomodeling.ics.forth.gr. It is free to use under the GNU General Public License

The Exceptionally Luminous Type Ia Supernova 2007If

SN 2007if was the third over-luminous Type Ia supernova (SN Ia) detected after 2003fg and 2006gz. We present the photometric and spectroscopic observations of the SN and its host by ROTSE-III, HET, and Keck. From the H a line identified in the host spectra, we determine a redshift of 0.0736. At this distance, the SN reached an absolute magnitude of -20.4, brighter than any other SNe Ia ever observed. If the source of luminosity is radioactive decay, a large amount of radioactive nickel (similar to 1.5 M(circle dot)) is required to power the peak luminosity, more than can be produced realistically in a Chandrasekhar mass progenitor. Low expansion velocity, similar to that of 2003fg, is also measured around the maximum light. The observations may suggest that SN 2007if was from a massive white dwarf progenitor, plausibly exploding with mass well beyond 1.4 M(circle dot). Alternatively, we investigate circumstellar interaction that may contribute to the excess luminosity.NASA NNX-08AN25G, NNX-08AV63GNSF AST-0707769, PHY-0801007Australian Research CouncilUniversity of New South WalesUniversity of TexasUniversity of MichiganAstronom

Attitudes and thoughts of medical practitioners towards their profession in the era of financial crisis in Greece

Introduction: The ongoing financial crisis occurring in Greece the last 8 years has affected the income of citizens in the country, their quality of life, as well as social and occupational relationships. Aim of this study assess attitudes towards working conditions and personal life and to explore quality of life, positive or negative attitudes, as well as disorders in sleep, mood, physical condition among doctors working or being trained in a tertiary hospital of NE Greece Methods: Included were 133 medical students and doctors of all ranks (61.7% males) practicing medicine in a University Tertiary Hospital in Greece. All of them answered a 31-item questionnaire regarding their working conditions, daytime activities and personal life, sleeping habits. Results: In general, the majority reported dissatisfaction with the work environment, the salary and they rated their quality of life worse than that of the general population. Weekly workload exceeded 60 hours for the majority. No difference between sexes was revealed, with the exception of use of energy drinks which was more prevalent in males (70.7% vs. 51%, p=0.022). Comparison between ranks revealed that medical students performed better in everyday activities and socialization, although prevalence of reported fatigue was higher in them. Finally, it was demonstrated that surgeons used more frequently medication to achieve sleep promotion (80.4% vs. 36%, p<0.001) and daily energy (78.4% vs. 44%, p<0.001). Conclusions: An overall dissatisfaction regarding workload, salary and quality of life is recorded among doctors of a tertiary hospital in Greece, with different coping strategies among subgroups. &nbsp

Improving music genre classification using automatically induced harmony rules

We present a new genre classification framework using both low-level signal-based features and high-level harmony features. A state-of-the-art statistical genre classifier based on timbral features is extended using a first-order random forest containing for each genre rules derived from harmony or chord sequences. This random forest has been automatically induced, using the first-order logic induction algorithm TILDE, from a dataset, in which for each chord the degree and chord category are identified, and covering classical, jazz and pop genre classes. The audio descriptor-based genre classifier contains 206 features, covering spectral, temporal, energy, and pitch characteristics of the audio signal. The fusion of the harmony-based classifier with the extracted feature vectors is tested on three-genre subsets of the GTZAN and ISMIR04 datasets, which contain 300 and 448 recordings, respectively. Machine learning classifiers were tested using 5 × 5-fold cross-validation and feature selection. Results indicate that the proposed harmony-based rules combined with the timbral descriptor-based genre classification system lead to improved genre classification rates

Modeling R Coronae Borealis Stars: Effects of He-Burning Shell Temperature and Metallicity

The R Coronae Borealis (RCB) stars are extremely hydrogen-deficient carbon stars which produce large amounts of dust, causing sudden deep declines in brightness. They are believed to be formed primarily through white dwarf mergers. In this paper, we use MESA to investigate how post-merger objects with a range of initial He-burning shell temperatures from 2.1 - 5.4 *10^8 K with solar and subsolar metallicities evolve into RCB stars. The most successful model of these has subsolar metallicity and an initial temperature near 3 *10^8 K. We find a strong dependence on initial He-burning shell temperature for surface abundances of elements involved in the CNO cycle, as well as differences in effective temperature and radius of RCBs. Elements involved in nucleosynthesis present around 1 dex diminished surface abundances in the 10% solar metallicity models, with the exception of carbon and lithium which are discussed in detail. Models with subsolar metallicities also exhibit longer lifetimes than their solar counterparts. Additionally, we find that convective mixing of the burned material occurs only in the first few years of post-merger evolution, after which the surface abundances are constant during and after the RCB phase, providing evidence for why these stars show a strong enhancement of partial He-burning products.Comment: 13 pages, 12 figures, accepted to MNRAS on August 15, 202