Influence of atomic polarization and horizontal illumination on the Stokes profiles of the He I 10830 multiplet

The polarization observed in the spectral lines of the He I 10830 multiplet carries valuable information on the dynamical and magnetic properties of plasma structures in the solar chromosphere and corona, such as spicules, prominences, filaments, emerging magnetic flux regions, etc. Here we investigate the influence of atomic level polarization on the emergent Stokes profiles for a broad range of magnetic field strengths, in both 90 degree and forward scattering geometry. We show that, contrary to a widespread belief, the selective emission and absorption processes caused by the presence of atomic level polarization may have an important influence on the emergent linear polarization, even for magnetic field strengths as large as 1000 G. Consequently, the modeling of the Stokes Q and U profiles should not be done by taking only into account the contribution of the transverse Zeeman effect within the framework of the Paschen-Back effect theory, unless the magnetic field intensity of the observed plasma structure is sensibly larger than 1000 G. We point out also that in low-lying optically thick plasma structures, such as those of active region filaments, the (horizontal) radiation field generated by the structure itself may substantially reduce the positive contribution to the anisotropy factor caused by the (vertical) radiation field coming from the underlying solar photosphere, so that the amount of atomic level polarization may turn out to be negligible. Only under such circumstances may the emergent linear polarization of the He I 10830 multiplet in such regions of the solar atmosphere be dominated by the contribution caused by the transverse Zeeman effect.Comment: Accepted for publication in The Astrophysical Journal (It is tentatively scheduled for the ApJ January 20, 2007 issue

A New Exact Method for Line Radiative Transfer

We present a new method, the Coupled Escape Probability (CEP), for exact calculation of line emission from multi-level systems, solving only algebraic equations for the level populations. The CEP formulation of the classical two-level problem is a set of {\em linear equations}, and we uncover an exact analytic expression for the emission from two-level optically thick sources that holds as long as they are in the "effectively thin" regime. In comparative study of a number of standard problems, the CEP method outperformed the leading line transfer methods by substantial margins. The algebraic equations employed by our new method are already incorporated in numerous codes based on the escape probability approximation. All that is required for an exact solution with these existing codes is to augment the expression for the escape probability with simple zone-coupling terms. As an application, we find that standard escape probability calculations generally produce the correct cooling emission by the CII 158 mic line but not by the $^3$P lines of OI.Comment: To be published in MNRAS, 13 pages, 10 figure

Depolarizing collisions with hydrogen: neutral and singly ionized alkaline earths

Depolarizing collisions are elastic or quasielastic collisions that equalize the populations and destroy the coherence between the magnetic sublevels of atomic levels. In astrophysical plasmas, the main depolarizing collider is neutral hydrogen. We consider depolarizing rates on the lowest levels of neutral and singly ionized alkaly-earths Mg I, Sr I, Ba I, Mg II, Ca II, and Ba II, due to collisions with H. We compute ab initio potential curves of the atom-H system and solve the quantum mechanical dynamics. From the scattering amplitudes we calculate the depolarizing rates for Maxwellian distributions of colliders at temperatures T <10000 K. A comparative analysis of our results and previous calculations in the literature is done. We discuss the effect of these rates on the formation of scattering polarization patterns of resonant lines of alkali-earths in the solar atmosphere, and their effect on Hanle effect diagnostics of solar magnetic fields.Comment: 18 pages, 3 figures. Summitted to ApJ (2014

On the difference of torus geometry between hidden and non-hidden broad line active galactic nuclei

We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGN) with clumpy torus models. We compiled high spatial resolution ($\sim 0.3$--$0.7$ arcsec) mid-IR $N$-band spectroscopy, $Q$-band imaging and nuclear near- and mid-IR photometry from the literature. Combining these nuclear near- and mid-IR observations, far-IR photometry and clumpy torus models, enables us to put constraints on the torus properties and geometry. We divide the sample into three types according to the broad line region (BLR) properties; type-1s, type-2s with scattered or hidden broad line region (HBLR) previously observed, and type-2s without any published HBLR signature (NHBLR). Comparing the torus model parameters gives us the first quantitative torus geometrical view for each subgroup. We find that NHBLR AGN have smaller torus opening angles and larger covering factors than those of HBLR AGN. This suggests that the chance to observe scattered (polarized) flux from the BLR in NHBLR could be reduced by the dual effects of (a) less scattering medium due to the reduced scattering volume given the small torus opening angle and (b) the increased torus obscuration between the observer and the scattering region. These effects give a reasonable explanation for the lack of observed HBLR in some type-2 AGN.Comment: 13 pages, 5 figures, accepted for publication in Ap

Molecular survey of CRL618

We present the complete data set, model and line identification of a survey of the emission from the C-rich protoplanetary nebula CRL 618 performed with the IRAM-30m telescope in the following frequency ranges: 80.25-115.75 GHz, 131.25-179.25 GHz, and 204.25-275.250 GHz. A selection of lines from different species has been used in previous works to derive the structure of the source, its physical conditions and the chemical abundances in the different gas regions. In this work, we have used this information to run a global simulation of the spectrum in order to check the consistency of the model and to ease the task of line identification. The total number of lines that have a correspondence in both data and model is ~3100, although quite often in this object many lines blend into complex features so that the model, that takes into account line blending, is a key tool at this stage of the analysis. Of all the lines that we have been able to label, ~55% of them belong to the different forms of HC3N, and ~18% to those of HC5N. The density of remaining unidentified features above the 3sigma limit is only one per ~2.1 GHz (74 features), which is unprecedented in the analysis of this type of large millimeter-wave line surveys.Comment: Accepted in ApJ (November 2006). Figures bitmapped to lower resolution. The complete set of tables and figures will be published only electronically (ApJ online

Post-acute COVID-19 syndrome. Incidence and risk factors: A Mediterranean cohort study

Objectives: This study aims to analyze the incidence of Post-acute COVID-19 syndrome (PCS) and its components, and to evaluate the acute infection phase associated risk factors.Methods: A prospective cohort study of adult patients who had recovered from COVID-19 (27th February to 29th April 2020) confirmed by PCR or subsequent seroconversion, with a systematic assessment 10-14 weeks after disease onset. PCS was defined as the persistence of at least one clinically relevant symptom, or abnormalities in spirometry or chest radiology. Outcome predictors were analyzed by multiple logistic regression (OR; 95%CI).Results: Two hundred seventy seven patients recovered from mild (34.3%) or severe (65.7%) forms of SARS-CoV-2 infection were evaluated 77 days (IQR 72-85) after disease onset. PCS was detected in 141 patients (50.9%; 95%CI 45.0-56.7%). Symptoms were mostly mild. Alterations in spirometry were noted in 25/269 (9.3%), while in radiographs in 51/277 (18.9%). No baseline clinical features behaved as independent predictors of PCS development.Conclusions: A Post-acute COVID-19 syndrome was detected in a half of COVID19 survivors. Radiological and spirometric changes were mild and observed in less than 25% of patients. No baseline clinical features behaved as independent predictors of Post-acute COVID-19 syndrome development

Mapping Solar Magnetic Fields from the Photosphere to the Base of the Corona

Routine ultraviolet imaging of the Sun's upper atmosphere shows the spectacular manifestation of solar activity; yet we remain blind to its main driver, the magnetic field. Here we report unprecedented spectropolarimetric observations of an active region plage and its surrounding enhanced network, showing circular polarization in ultraviolet (Mg II $h$ & $k$ and Mn I) and visible (Fe I) lines. We infer the longitudinal magnetic field from the photosphere to the very upper chromosphere. At the top of the plage chromosphere the field strengths reach more than 300 gauss, strongly correlated with the Mg II $k$ line core intensity and the electron pressure. This unique mapping shows how the magnetic field couples the different atmospheric layers and reveals the magnetic origin of the heating in the plage chromosphere.Comment: 50 pages, 11 figures, 1 table, published in Science Advance

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Efectividad terapéutica y seguridad de la radioembolización con microesferas marcadas con Itrio-90 en tumores hepáticos: Revisión sistemática y Meta-análisis

Los tumores hepáticos, tanto primarios como metastásicos, constituyen un importante problema de salud a nivel mundial, con una incidencia que va en aumento junto a un incremento de la prevalencia de estadios intermedios y avanzados de mal pronóstico. La radioembolización con Itrio-90 (RE-Y90) se presenta como una alternativa terapéutica prometedora en estos tumores frente a los tratamientos loco-regionales aceptados en la práctica clínica pero aún sin determinar. La RE-Y90 es una forma de braquiterapia que consiste en la administración de microesferas radiactivas marcadas con Y-90 a través de la arteria hepática. Se comercializan dos tipos de microesferas, las de resina (SIR-Sphere®) y las de vidrio (TheraSphere®), con diferentes características. El tratamiento implica una fase de planificación previa, con el fin de reducir las complicaciones al tiempo que administrar la dosis efectiva adecuada, y la posterior administración de las microesferas. La RE se basa en la doble vascularización hepática: el parénquima sano se irriga casi de forma exclusiva de la porta mientras que la irrigación de los procesos tumorales, tanto primarios como secundarios, depende de la arteria hepática. Esta dualidad permite administrar de forma altamente selectiva el tratamiento sobre el tejido tumoral, evitando el tejido sano. El objetivo de este informe es estudiar la efectividad terapéutica y la seguridad de la RE-Y90, sola o combinada con otros tratamientos, frente al tratamiento estándar en pacientes con tumores hepáticos primarios o metastásicos.ÍNDICE DE TABLAS ÍNDICE DE FIGURAS RESUMEN EXECUTIVE SUMMARY ACRÓNIMOS Y ABREVIATURAS (EN ORDEN ALFABÉTICO) ALGUNOS CONCEPTOS QUE SE MANEJAN EN ESTE INFORME I. INTRODUCCIÓN Descripción de la patología Carcinoma hepatocelular Colangiocarcinona intrahepático Metástasis hepática Descripción de la Radioembolización con Y-90 Mecanismo de acción Tipos de microesferas Planificación del tratamiento Cálculo de dosis Inyección de microesferas . Situación de autorización y uso de la RE-Y90 II. OBJETIVO III. METODOLOGÍA III.1. Búsqueda de información III.1.1. Fuentes de información III.1.2. Proceso de selección de estudios III.1.3. Gestión de referencias III.2. Identificación y selección de estudios III.2.1 Proceso de selección de los estudios III.2.2 Criterios de inclusión y exclusión III.3. Evaluación de la calidad de la metodología. Riesgo de sesgo III.4. Extracción de datos de los artículos III.5. Análisis de datos y síntesis de resultados: análisis cualitativo y meta-análisis IV. RESULTADOS IV.1. Resultados de la búsqueda, identificación y selección de estudios IV.2. Artículos incluidos. Extracción de datos IV.3. Calidad metodológica de los estudios incluidos IV.4. Estudios comparativos. Resultados del análisis cualitativo y cuantitativo. Tablas de evidencia Análisis cualitativo Meta-análisis. Análisis cuantitativo IV.5. Estudios no comparativos. Resultados del análisis cualitativo. Tablas de evidencia IV.6. Ensayos clínicos en marcha V. DISCUSIÓN 1. Resumen de los principales resultados de esta revisión Efectividad terapéutica. Medidas de resultados Respuesta tumoral. Criterios Toxicidad. Eventos adversos Calidad de vida 2. Valoración de la calidad de los estudios incluidos 3. Otros estudios similares. Acuerdos y desacuerdos IETS y RS Encuesta sobre la utilización de RE-Y90 Estudios de costes 4. Limitaciones. Potenciales sesgos de esta revisión VI. CONCLUSIONES Conclusiones para la práctica clínica Recomendaciones para futuras investigaciones VII. BIBLIOGRAFÍA Anexo I. Estrategias de búsqueda Anexo II. Formulario de extracción de datos Anexo III. Criterios de respuesta tumoral Anexo IV. Artículos excluidos en esta revisión Anexo V. Tablas y extracción de datos Anexo VI. Ensayos clínicos en marcha: principales característica