5,170 research outputs found
Resolving the clumpy circumstellar environment of the B[e] supergiant LHA 120-S 35
Context. B[e] supergiants are massive post-main-sequence stars, surrounded by a complex circumstellar environment where moleculesand dust can survive. The shape in which the material is distributed around these objects and its dynamics as well as the mechanismsthat give rise to these structures are not well understood.Aims. The aim of this work is to deepen our knowledge of the structure and kinematics of the circumstellar disc of the B[e] supergiantLHA 120-S 35.Methods. High-resolution optical spectra were obtained in three different years. Forbidden emission lines, that contribute to trace thedisc at different distances from the star, are modelled in order to determine the kinematical properties of their line-forming regions,assuming Keplerian rotation. In addition, we used low-resolution near-infrared spectra to explore the variability of molecular emission.Results. LHA 120-S 35 displays an evident spectral variability in both optical and infrared regions. The P-Cygni line profiles of H i,as well as those of Fe ii and O i, suggest the presence of a strong bipolar clumped wind. We distinguish density enhancements in theP-Cygni absorption component of the first Balmer lines, which show variations in both velocity and strength. The P-Cygni profileemission component is double-peaked, indicating the presence of a rotating circumstellar disc surrounding the star. We also observeline-profile variations in the permitted and forbidden features of Fe ii and O i. In the infrared, we detect variations in the intensity ofthe H i emission lines as well as in the emission of the CO band-heads. Moreover, we find that the profiles of each [Ca ii] and [O i]emission lines contain contributions from spatially different (complete or partial) rings. Globally, we find evidence of detached multi-ring structures, revealing density variations along the disc. We identify an inner ring, with sharp edge, where [Ca ii] and [O i] linesshare their forming region with the CO molecular bands. The outermost regions show a complex structure, outlined by fragmentedclumps or partial-ring features of Ca ii and O i. Additionally, we observe variations in the profiles of the only visible absorptionfeatures, the He i lines.Conclusions. We suggest that LHA 120-S 35 has passed through the red-supergiant (RSG) phase and evolves back bluewards in theHertzsprung-Russell diagram. In this scenario, the formation of the complex circumstellar structure could be the result of the wind-wind interactions of the post-RSG wind with the previously ejected material from the RSG. The accumulation of material in thecircumstellar environment could be attributed to enhanced mass-loss, probably triggered by stellar pulsations. However, the presenceof a binary companion can not be excluded. Finally, we find that LHA 120-S 35 is the third B[e] supergiant belonging to a youngstellar cluster.Fil: Torres, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Cidale, Lydia Sonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Kraus, M.. Tartu Observatory, Estonia; Estonia. Astronomický Ústav, Akademie Ved Ceské Republiky; República ChecaFil: Arias, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Barba, Rodolfo Hector. Universidad de La Serena; ChileFil: Maravelias, G.. Universidad de Valparaiso; Chile. Astronomický Ústav, Akademie Ved Ceské Republiky; República ChecaFil: Borges Fernandes, M.. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; Brasi
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Teleneurology clinics for polyneuropathy: a pilot study.
INTRODUCTION:Polyneuropathy (PN) is a common condition with significant morbidity. We developed tele-polyneuropathy (tele-PN) clinics to improve access to neurology and increase guideline-concordant PN care. This article describes the mixed-methods evaluation of pilot tele-PN clinics at three community sites within the Greater Los Angeles VA Healthcare System. METHODS:For the first 25 patients (48 scheduled visits), we recorded the duration of the tele-PN visit and exam; the performance on three guideline-concordant care indicators (PN screening labs, opiate reduction, physical therapy for falls); and patient-satisfaction scores. We elicited comments about the tele-PN clinic from patients and the clinical team. We combined descriptive statistics with qualitative themes to determine the feasibility and acceptability of the tele-PN clinics. RESULTS:The average tele-PN encounter and exam times were 28.5 and 9.1 min, respectively. PN screening lab completion increased from 80 to 100%. Opiate freedom improved from 68 to 88%. Physical therapy for patients with recent falls increased from 58 to 100%. The tele-PN clinic was preferred for follow-up over in-person clinics in 86% of cases. Convenience was paramount to the clinic's success, saving an average of 231 min per patient in round-trip travel. The medical team's caring and collaborative spirit received high praise. While the clinic's efficiency was equal or superior to in-person care, the limited treatment options for PN and the small clinical exam space are areas for improvement. CONCLUSION:In this pilot, we were able to efficiently see and examine patients remotely, promote guideline-concordant PN care, and provide a high-satisfaction encounter
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Saliency-driven system models for cell analysis with deep learning.
Background and objectivesSaliency refers to the visual perception quality that makes objects in a scene to stand out from others and attract attention. While computational saliency models can simulate the expert's visual attention, there is little evidence about how these models perform when used to predict the cytopathologist's eye fixations. Saliency models may be the key to instrumenting fast object detection on large Pap smear slides under real noisy conditions, artifacts, and cell occlusions. This paper describes how our computational schemes retrieve regions of interest (ROI) of clinical relevance using visual attention models. We also compare the performance of different computed saliency models as part of cell screening tasks, aiming to design a computer-aided diagnosis systems that supports cytopathologists.MethodWe record eye fixation maps from cytopathologists at work, and compare with 13 different saliency prediction algorithms, including deep learning. We develop cell-specific convolutional neural networks (CNN) to investigate the impact of bottom-up and top-down factors on saliency prediction from real routine exams. By combining the eye tracking data from pathologists with computed saliency models, we assess algorithms reliability in identifying clinically relevant cells.ResultsThe proposed cell-specific CNN model outperforms all other saliency prediction methods, particularly regarding the number of false positives. Our algorithm also detects the most clinically relevant cells, which are among the three top salient regions, with accuracy above 98% for all diseases, except carcinoma (87%). Bottom-up methods performed satisfactorily, with saliency maps that enabled ROI detection above 75% for carcinoma and 86% for other pathologies.ConclusionsROIs extraction using our saliency prediction methods enabled ranking the most relevant clinical areas within the image, a viable data reduction strategy to guide automatic analyses of Pap smear slides. Top-down factors for saliency prediction on cell images increases the accuracy of the estimated maps while bottom-up algorithms proved to be useful for predicting the cytopathologist's eye fixations depending on parameters, such as the number of false positive and negative. Our contributions are: comparison among 13 state-of-the-art saliency models to cytopathologists' visual attention and deliver a method that the associate the most conspicuous regions to clinically relevant cells
When a threatened species becomes a threat: a key to reading the Habitats Directive based on occurrence and distribution of Cerambyx cerdo L. in Mediterranean urban and peri-urban areas
Abstract
Cerambyx cerdo is a large saproxylic species included in the Annex IV of the European Habitats Directive as a 'priority species'.
Although C. cerdo populations have shown a significant decline in size and distribution in central and northern European forests, in the Mediterranean basin it is often considered as a pest in urban and peri‐urban areas.
Based on European legislations currently in use, we propose a simplified decision‐making flowchart that should be followed regarding the adoption of different control measures against severe C. cerdo infestations
On the evolutionary state of massive stars in transition phases in M33
The advanced stages of several high-mass stars are characterized by episodic mass-loss shed during phases of instability.Key for assigning these stars a proper evolutionary state is to assess the composition and geometry of their ejecta alongside the stellar properties. We selected five hot luminous blue variable candidates in M33 to refine their classification, investigate their circumstellar environments, and explore their evolutionary properties. Being accessible targets in the near-infrared, we conducted medium-resolution spectroscopy with GNIRS/GEMINI in the K-band to investigate their molecular circumstellar environments. Two stars were found to display CO emission, which was modelled to emerge from a circumstellar or circumbinary Keplerian disc/ring. The identification of the carbon isotope 13C and, for one of the two stars, a significantly low 12CO/13CO ratio, implies an evolved stellar state. As both CO emission stars are highly luminous and hence do not undergo a red supergiant phase, we suggest that stripping processes and equatorial high-density ejecta due to fast rotation are responsible for the enrichment of the stellar surface with processedmaterial from the core.Acandidate B[e]SG displays an absorption CO profile, which may be attributed to a jet or stellar pulsations. The featureless infrared spectra of two stars suggest a low-density gas shell or dissipation of the molecule due to the ionizing temperature of the star. We propose spectroscopic monitoring of our targets to evaluate the stability of the CO molecule and assess the time-dependent dynamics of the circumstellar gas structures.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat
Modeling of molecules in circumstellar media
Las estrellas B[e] se caracterizan por poseer lı́neas espectrales en emisión, tanto de transiciones prohibidas como permitidas, producidas en el disco que rodea a la estrella. Las condiciones de temperatura ydensidad en estos discos permiten la formación de moléculas, cuya presencia se manifiesta en la observación de bandas moleculares en emisión. En este trabajo presentamos el código que hemos desarrollado que nos permite modelar las bandas en emisión de distintas moléculas diatómicas como CO, SiO, CS, SiS, NH, etc. El programatiene en cuenta los distintos isótopos que componen las moléculas, ya que éstos afectan significativamente a las bandas. Con este programa podemos obtener los espectros combinados tanto de moléculas compuestas por distintos isótopos como de la superposición de distintas moléculas. Comparando con las observaciones, podemos usar estosespectros teóricos no sólo para determinar la presencia de las moléculas, sino también otros parámetros, como la temperatura y densidad de las regiones de formación de las moléculas en el disco, la velocidad de rotación, y la región del disco en donde se encuentran las moléculas. Además los podemos utilizar para determinar la relación de abundancia de los distintos isótopos de una molécula, que puede ser utilizada para determinar la etapa evolutiva de la estrella.B[e] stars are characterized by having spectral lines in emission, both of forbiden and allowed transitions, produced in the disk that surrounds the star. The temperature and density conditions in these disks allow the formation of molecules, whose presence is manifested in the observation of molecular bands in emission. In this work we present the code that we have developed which allows us to model the emission bands of different diatomic molecules, such as CO, SiO, CS, SiS, NH, etc. The program takes into account the different isotopes that make up the molecules, since these significantly affect the bands. With this program we can obtain the combined spectra of molecules composed of different isotopes and the superposition of different molecules. Comparing with the observations, we can use these theoretical spectra not only to determine the presence of the molecules, but also other parameters, such as the temperature and density of the regions of formation of the molecules in the disk, the velocity of rotation, and the region of the disk where the molecules are found. We can also use them to determine the abundance ratio of the different isotopes of a molecule, which can be used to determine the evolutionary stage of the star.Fil: Vallverdú, Rodolfo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Kraus, M.. No especifíca;Fil: Torres, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Arias, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina62° Reunión Anual de la Asociación Argentina de AstronomíaArgentinaAsociación Argentina de Astronomí
Burdigalian deposits of the Santa Cruz Formation in the Sierra Baguales, Austral (Magallanes) Basin: Age, depositional environment and vertebrate fossils
Indexación: Web of Science; Scielo.ABSTRACT. A succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales,
northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago
Argentino region in Santa Cruz Province, Argentina. These include the Estancia 25 de Mayo Formation and the basal
part of the Santa Cruz Formation. The lithological correlation is also confirmed by detrital zircon ages (maximum age
of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a postColhuehuapian,
pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to
17.8 Ma. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe
in southwestern Argentina, supporting the assumption of a regional continuity between these deposits. A measured
lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small,
meandering rivers and ephemeral floodplain lakes. The sedimentation coincides with intensified uplift of the Patagonian
Andes during the ‘Quechua Phase’ of Andean tectonism, which is reflected by a change in paleocurrent directions from
northwest to east-northeast.
Keywords: Burdigalian, Santa Cruz Formation, Santacrucian SALMA, ‘Notohippidian’ fauna, Meandering rivers.RESUMEN. Una sucesión de estratos marinos y continentales en el flanco meridional del cerro Cono, en la sierra Baguales, al noreste de Torres del Paine, se correlaciona con estratos al sur de la región de lago Argentino en la Provincia de Santa Cruz, República Argentina. Estas unidades incluyen la Formación Estancia 25 de Mayo y la parte basal de la Formación Santa Cruz. La correlación litológica es, además, confirmada por datación de circones detríticos (edad máxima de 18,23±0,26 Ma) y un variado ensamble de vertebrados fósiles terrestres de edad post-Colhuehuapense a pre-Santacrucense en la escala de Edades Mamífero Sudamericanas (EMAS), con un rango temporal de entre 19 a 17,8 Ma. Edades similares han sido reportadas para la parte basal de la Formación Santa Cruz, en estancia Quién Sabe, en el suroeste de Argentina, ratificando la continuidad regional entre estos depósitos. Se presenta una columna estratigráfica y se interpreta el ambiente de depositación como una llanura costera con pequeños ríos sinuosos y lagos efímeros. La edad de sedimentación coincide con el solevantamiento de los Andes Patagónicos durante la 'Fase Quechua', lo que se ve reflejado por un cambio en la dirección de las paleocorrientes desde el noroeste hacia el este-noreste.http://ref.scielo.org/csxwd
Discovery of Raman-scattered lines in the massive luminous emission-line: Star LHA 115-S 18
LHA 115-S 18 is a very peculiar emission-line star exhibiting the B[e] phenomenon. Located in the Small Magellanic Cloud, its spectrum shows features of an extremely wide range of excitation and ionization stages, extending from highly ionized atomic lines (Si IV, CIV, HeII) in the ultraviolet and optical regions to molecular emission bands of CO and TiO in the optical and infrared regions. The most distinguishing spectral characteristic of LHA 115-S 18 is the high variability detected in the He II λ4686 emission line, which can be a very conspicuous or completely invisible feature. In thiswork,we report on another peculiarity ofLHA115-S 18. From high-resolution optical spectra taken between 2000 and 2008, we discovered the appearance and strengthening of two emission features at λλ6825 and 7082Å, which we have identified as Raman-scattered lines. This is the first time that these lines have been detected in the spectrum of a massive luminous B[e] star. As the classification of LHA 115-S 18 is highly controversial, we discuss how the discovery of the appearance of Raman-scattered lines in this peculiar star might help us to solve this puzzle.Facultad de Ciencias Astronómicas y Geofísica
Modeling of emission lines in low-ionization winds of B-type stars
En el contexto de la aparición del nuevo material observacional provisto por la misión espacial Gaia, y enfocado en estrellas de tipo espectral B peculiares, se desarrolla un modelo para simular el espectro de lı́neas de elementos una vez ionizados como Ca ii y Mg ii fuera del equilibrio termodinámico local. El cálculo se realiza para un rango de temperaturas efectivas y gravedades superficiales, para diferentes distribuciones de temperatura y velocidad en el material circunestelar y distintas tasas de pérdida de masa. Los perfiles sintéticos obtenidos son capaces de reproducir los rasgos generales de las lı́neas espectrales observadas como, por ejemplo, perfiles P Cygni.Motivated by the availability of new observational material provided by Gaia mission, and focused on peculiar B-type stars, we develop a model to simulate the non-LTE line profiles of ionized elements such as Ca ii and Mg ii. The calculation is performed for a range of effective temperature and surface gravity, for different temperature and velocity distributions of the circumstellar material as well as different stellar mass-loss rates. The obtained synthetic profiles are capable of reproducing the general features of the observed spectral lines, such as P Cygni-type profiles.Fil: Mercanti, Lorena Verónica. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cidale, Lydia Sonia. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Torres, Andrea Fabiana. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cochetti, Yanina Roxana. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Kraus, M.. No especifíca;62º Reunión Anual de la Asociación Argentina de AstronomíaArgentinaAsociación Argentina de Astronomí
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