The population of SNe/SNRs in the starburst galaxy Arp 220. A self-consistent analysis of 20 years of VLBI monitoring

The nearby ultra-luminous infrared galaxy (ULIRG) Arp 220 is an excellent laboratory for studies of extreme astrophysical environments. For 20 years, Very Long Baseline Interferometry (VLBI) has been used to monitor a population of compact sources thought to be supernovae (SNe), supernova remnants (SNRs) and possibly active galactic nuclei (AGNs). Using new and archival VLBI data spanning 20 years, we obtain 23 high-resolution radio images of Arp 220 at wavelengths from 18 cm to 2 cm. From model-fitting to the images we obtain estimates of flux densities and sizes of all detected sources. We detect radio continuum emission from 97 compact sources and present flux densities and sizes for all analysed observation epochs. We find evidence for a LD-relation within Arp 220, with larger sources being less luminous. We find a compact source LF $n(L)\propto L^\beta$ with $\beta=-2.19\pm0.15$, similar to SNRs in normal galaxies. Based on simulations we argue that there are many relatively large and weak sources below our detection threshold. The observations can be explained by a mixed population of SNe and SNRs, where the former expand in a dense circumstellar medium (CSM) and the latter interact with the surrounding interstellar medium (ISM). Nine sources are likely luminous, type IIn SNe. This number of luminous SNe correspond to few percent of the total number of SNe in Arp 220 which is consistent with a total SN-rate of 4 yr$^{-1}$ as inferred from the total radio emission given a normal stellar initial mass function (IMF). Based on the fitted luminosity function, we argue that emission from all compact sources, also below our detection threshold, make up at most 20\% of the total radio emission at GHz frequencies.Comment: Accepted for publication in Astronomy and Astrophysic

VLBI observations of SN 2008iz: I. Expansion velocity and limits on anisotropic expansion

We present observations of the recently discovered supernova 2008iz in M82 with the VLBI High Sensitivity Array at 22 GHz, the Very Large Array at frequencies of 1.4, 4.8, 8.4, 22 and 43 GHz, and the Chandra X-ray observatory. The supernova was clearly detected on two VLBI images, separated by 11 months. The source shows a ring-like morphology and expands with a velocity of ~23000 km/s. The most likely explosion date is in mid February 2008. The measured expansion speed is a factor of ~2 higher than expected under the assumption that synchrotron self-absorption dominates the light curve at the peak, indicating that this absorption mechanism may not be important for the radio emission. We find no evidence for an asymmetric explosion. The VLA spectrum shows a broken power law, indicating that the source was still optically thick at 1.4 GHz in April 2009. Finally, we report upper limits on the X-ray emission from SN 2008iz and a second radio transient recently discovered by MERLIN observations.Comment: accepted Astronomy & Astrophysics, 9 pages, 8 figures, also available at http://www.mpifr-bonn.mpg.de/staff/abrunthaler/pub.shtm

Hot-Jupiters and hot-Neptunes: a common origin?

We compare evolutionary models for close-in exoplanets coupling irradiation and evaporation due respectively to the thermal and high energy flux of the parent star with observations of recently discovered new transiting planets. The models provide an overall good agreement with observations, although at the very limit of the quoted error bars of OGLE-TR-10, depending on its age. Using the same general theory, we show that the three recently detected hot-Neptune planets (GJ436, $\rho$ Cancri, $\mu$ Ara) may originate from more massive gas giants which have undergone significant evaporation. We thus suggest that hot-Neptunes and hot-Jupiters may share the same origin and evolution history. Our scenario provides testable predictions in terms of the mass-radius relationships of these hot-Neptunes.Comment: 5 pages, 2 figures, accepted in A&A Lette

Distribution, conservation status and proposed measures for preservation of Radiodiscus microgastropods in Chile

The genus Radiodiscus includes minute terrestrial snails occurring throughout the American continent. We assessed the conservation status of eight poorly known Chilean Radiodiscus species using the International Union for Conservation of Nature (IUCN) and NatureServe categories and criteria. Under the IUCN guidelines the species were assessed using the Criterion B of geographic range, which considers the extent of occurrence (EOO) and area of occupancy (AOO) as subcriteria. For NatureServe we used these two parameters plus the number of occurrences, ecological viability, and threats. Considering species rarity and possible sampling bias, we also used ecological niche modeling to determine climate and environmental tolerances and predict potential species distributions analyzing bioclimatic and geographical layers. Radiodiscus australis, R. coarctatus and R. quillajicola were listed as Critically Endangered by IUCN and NatureServe standards; R. coppingeri, R. flammulatus, R. magellanicus and R. villarricensis as Endangered by both methods; while R. riochicoensis as Endangered by IUCN standards and Vulnerable by NatureServe standards. Niche modeling results indicated that Radiodiscus species respond to different environmental conditions and that the predicted distribution areas contain suitable habitats beyond the current ranges, which may be helpful for future management plans. Nature-based sport tourism, forestry activities, urbanization, roads, pollution, mining, forest fires, livestock, volcanism, tsunamis, soil erosion and introduced species are among the major threats affecting these snails. Based on the low number of occurrences and the threats identified, the most at-risk species are R. coarctatus and R. quillajicola (one record), R. australis (two records) and R. villarricensis (three records); the latter two lacking occurrences within protected areas. Compiling our findings, we propose a list of actions to preserve Chilean Radiodiscus species

Localized thinning for strain concentration in suspended germanium membranes and optical method for precise thickness measurement

We deposited Ge layers on (001) Si substrates by molecular beam epitaxy and used them to fabricate suspended membranes with high uniaxial tensile strain. We demonstrate a CMOS-compatible fabrication strategy to increase strain concentration and to eliminate the Ge buffer layer near the Ge/Si hetero-interface deposited at low temperature. This is achieved by a two-steps patterning and selective etching process. First, a bridge and neck shape is patterned in the Ge membrane, then the neck is thinned from both top and bottom sides. Uniaxial tensile strain values higher than 3% were measured by Raman scattering in a Ge membrane of 76 nm thickness. For the challenging thickness measurement on micrometer-size membranes suspended far away from the substrate a characterization method based on pump-and-probe reflectivity measurements was applied, using an asynchronous optical sampling technique.EC/FP7/628197/EU/Heat Propagation and Thermal Conductivity in Nanomaterials for Nanoscale Energy Management/HEATPRONAN

Imaging of Tendons

Magnetic resonance imaging (MRI) and ultrasound (US) are useful radiologic modalities that allow adequate evaluation of tendon anatomy and integrity. Each modality contains unique advantages as diagnostic tools, allowing detection of tendon injuries and pathology. This chapter focuses on the key imaging features of tendons in both ultrasound and magnetic resonance, with emphasis on the major joints such as the shoulder, elbow, hand/wrist, hip, knee and foot/ankle joints. Each section provides a review of standard magnetic resonance imaging protocols and ultrasound technique, along with a discussion of the radiologic appearance of the most common tendon pathology affecting each joint

VLTI/AMBER observations of cold giant stars: atmospheric structures and fundamental parameters

Aims. The main goal of this research is to determine the angular size and the atmospheric structures of cool giant stars (epsilon Oct, beta Peg, NU Pav, psi Peg, and gamma Hya) and to compare them with hydrostatic stellar model atmospheres, to estimate the fundamental parameters, and to obtain a better understanding of the circumstellar environment. Methods. We conducted spectro-interferometric observations of epsilon Oct, beta Peg, NU Pav, and psi Peg in the near-infrared K band (2.13-2.47 mu m), and gamma Hya (1.9-2.47 mu m) with the VLTI/AMBER instrument at medium spectral resolution (similar to 1500). To obtain the fundamental parameters, we compared our data with hydrostatic atmosphere models (PHOENIX). Results. We estimated the Rosseland angular diameters of epsilon Oct, beta Peg, NU Pav, psi Peg, and gamma Hya to be 11.66 +/- 1.50 mas, 16.87 +/- 1.00 mas, 13.03 +/- 1.75 mas, 6.31 +/- 0.35 mas, and 3.78 +/- 0.65 mas, respectively. Together with distances and bolometric fluxes (obtained from the literature), we estimated radii, effective temperatures, and luminosities of our targets. In the beta Peg visibility, we observed a molecular layer of CO with a size similar to that modeled with PHOENIX. However, there is an additional slope in absorption starting around 2.3 m. This slope is possibly due to a shell of H2O that is not modeled with PHOENIX (the size of the layer increases to about 5% with respect to the near-continuum level). The visibility of psi Peg shows a low increase in the CO bands, compatible with the modeling of the PHOENIX model. The visibility data of epsilon Oct, NU Pav, and gamma Hya show no increase in molecular bands. Conclusions. The spectra and visibilities predicted by the PHOENIX atmospheres agree with the spectra and the visibilities observed in our stars (except for beta Peg). This indicates that the opacity of the molecular bands is adequately included in the model, and the atmospheres of our targets have an extension similar to the modeled atmospheres. The atmosphere of beta Peg is more extended than that predicted by the model. The role of pulsations, if relevant in other cases and unmodeled by PHOENIX, therefore seems negligible for the atmospheric structures of our sample. The targets are located close to the red limits of the evolutionary tracks of the STAREVOL model, corresponding to masses between 1 M-circle dot and 3 M-circle dot. The STAREVOL model fits the position of our stars in the Hertzsprung-Russell (HR) diagram better than the Ekstrom model does. STAREVOL includes thermohaline mixing, unlike the Ekstrom model, and complements the latter for intermediate-mass stars

Use of aequorin-based indicators for monitoring Ca2+ in acidic organelles

Over the last years, there is accumulating evidence that acidic organelles can accumulate and release Ca2+ upon cell activation. Hence, reliable recording of Ca2+ dynamics in these compartments is essential for understanding the physiopathological aspects of acidic organelles. Genetically encoded Ca2+ indicators (GECIs) are valuable tools to monitor Ca2+ in specific locations, although their use in acidic compartments is challenging due to the pH sensitivity of most available fluorescent GECIs. By contrast, bioluminescent GECIs have a combination of features (marginal pH sensitivity, low background, no phototoxicity, no photobleaching, high dynamic range and tunable affinity) that render them advantageous to achieve an enhanced signal-to-noise ratio in acidic compartments. This article reviews the use of bioluminescent aequorin-based GECIs targeted to acidic compartments. A need for more measurements in highly acidic compartments is identified

Chronic Obstructive Pulmonary Disease and Incidence of Hip Fracture: A Nested Case-Control Study in the EpiChron Cohort

Purpose: To determine whether chronic obstructive pulmonary disease (COPD) is a risk factor for hip fracture and identify other factors associated with hip fracture. Patients and Methods: Observational nested case-control study was conducted in Aragon, Spain in 2010. We included COPD patients aged >40 years, in the EpiChron cohort. Each COPD patient was matched for age, sex, and number of comorbidities with a control subject without COPD. Patients with an existing diagnosis of osteoporosis and those with hip fracture before 2011 were excluded. We collected baseline demographic, comorbidity, and pharmacological treatment data. During a 5-year follow-up period, we recorded the incidence of hip fracture. A logistic regression model was constructed to identify factors associated with hip fracture. Results: The study population consisted of 26, 517 COPD patients and the same number of controls (median [interquartile range] age, 74 [17] years; women, 24.7%). Smoking and heart failure were more frequent in COPD patients, and obesity, hypertension, diabetes, dyslipidemia, stroke, arthritis, and visual or hearing impairment were less frequent (all p<0.001). Consumption of benzodiazepines (p=0.037), bronchodilators (p<0.001), and corticosteroids (p<0.001) was higher in the COPD group, while that of beta-blockers and thiazides was lower (both p<0.001). During follow-up, 898 (1.7%) patients experienced hip fracture, with no differences observed between COPD and control patients. Multivariate analysis revealed that independent of COPD status, age, female sex, chronic liver disease, heart failure, and benzodiazepine use were independently associated with a higher risk of hip fracture, and obesity with a lower risk. In COPD patients, use of inhaled anticholinergics was independently associated with hip fracture (OR, 1.390; 95% CI 1.134-1.702; p=0.001). Conclusion: COPD is not a risk factor for a hip fracture within 5 years. The association between the use of inhaled anticholinergics and risk of hip fracture warrants further study