5 year Global 3-mm VLBI survey of Gamma-ray active blazars

The Global mm-VLBI Array (GMVA) is a network of 14 3\,mm and 7\,mm capable telescopes spanning Europe and the United States, with planned extensions to Asia. The array is capable of sensitive maps with angular resolution often exceeding 50\,$\mu$as. Using the GMVA, a large sample of prominent $\gamma$-ray blazars have been observed approximately 6 monthly from later 2008 until now. Combining 3\,mm maps from the GMVA with near-in-time 7\,mm maps from the VLBA-BU-BLAZAR program and 2\,cm maps from the MOJAVE program, we determine the sub-pc morphology and high frequency spectral structure of $\gamma$-ray blazars. The magnetic field strength can be estimated at different locations along the jet under the assumption of equipartition between magnetic field and relativistic particle energies. Making assumptions on the jet magnetic field configuration (e.g. poloidal or toroidal), we can estimate the separation of the mm-wave "core" and the jet base, and estimate the strength of the magnetic field there. The results of this analysis show that on average, the magnetic field strength decreases with a power-law $B \propto r^{-n}$, $n=0.3 \pm 0.2$. This suggests that on average, the mm-wave "core" is $\sim 1-3$\,pc downstream of the de-projected jet apex and that the magnetic field strength is of the order $B_{\rm{apex}} \sim 5-20$\,kG, broadly consistent with the predictions of magnetic jet launching (e.g. via magnetically arrested disks (MAD)).Comment: 6 pages, 1 figur

On the Calibration of Full-polarization 86GHz Global VLBI Observations

We report the development of a semi-automatic pipeline for the calibration of 86 GHz full-polarization observations performed with the Global Millimeter-VLBI array (GMVA) and describe the calibration strategy followed in the data reduction. Our calibration pipeline involves non-standard procedures, since VLBI polarimetry at frequencies above 43 GHz is not yet well established. We also present, for the first time, a full-polarization global-VLBI image at 86 GHz (source 3C 345), as an example of the final product of our calibration pipeline, and discuss the effect of instrumental limitations on the fidelity of the polarization images. Our calibration strategy is not exclusive for the GMVA, and could be applied on other VLBI arrays at millimeter wavelengths. The use of this pipeline will allow GMVA observers to get fully-calibrated datasets shortly after the data correlation.Comment: 10 pages, 10 figures. Accepted for publication in A&

Particle fluxes and their drivers in the Avilés submarine canyon and adjacent slope, central Cantabrian margin, Bay of Biscay

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Strong coupling between weakly guided semiconductor nanowire modes and an organic dye

The light-matter coupling between electromagnetic modes guided by a semiconductor nanowire and excitonic states of molecules localized in its surrounding media is studied from both classical and quantum perspectives, with the aim of describing the strong-coupling regime. Weakly guided modes (bare photonic modes) are found through a classical analysis, identifying those lowest-order modes presenting large electromagnetic fields spreading outside the nanowire while preserving their robust guided behavior. Experimental fits of the dielectric permittivity of an organic dye that exhibits excitonic states are used for realistic scenarios. A quantum model properly confirms through an avoided mode crossing that the strong-coupling regime can be achieved for this configuration, leading to Rabi splitting values above 100 meV. In addition, it is shown that the coupling strength depends on the fraction of energy spread outside the nanowire, rather than on the mode field localization. These results open up a new avenue towards strong-coupling phenomenology involving propagating modes in nonabsorbing media

Estudio de la vulnerabilidad sísmica del centro histórico de Tapachula, Chiapas, con el método del índice de vulnerabilidad

Los sismos destructores históricos y recientes han mostrado que el colapso de las edificaciones es el factor que más contribuye a la pérdida de vidas humanas. Un estudio de vulnerabilidad sísmica determina el nivel de seguridad de una zona urbana o de una serie de edificaciones ante los movimientos sísmicos que pueden ocurrir en dicho sitio. Mediante este tipo de estudio se hace un diagnóstico de niveles de desempeño de cada edificación y se evalúa su posible comportamiento y susceptibilidad al daño sísmico. En este trabajo se ha estimado lavulnerabilidad sísmica de 399 edificaciones de 22 manzanas del Centro Histórico de Tapachula, Chiapas, con dos métodos: primero el de clasificación tipológica según la Escala Macrosísmica Europea (EMS-98) y posteriormente mediante el método del índice de vulnerabilidad sísmica(MIV) de RISK-UE. Este método es un refinamiento del primero que cuantifica mejor los factores de construcción y comportamiento de cada edificio que modifican su vulnerabilidad. Los resultados obtenidos se presentan en tablas y mapas de lnerabilidad sísmica y muestran que en la zona estudiada predominan las edificaciones con clases de vulnerabilidad alta (B) y muy alta (A) y que la estimación de la vulnerabilidad aplicando los criterios de la Escala EMS mejoran significativamente al aplicar MIV, que detecta un incremento de construcciones de clase A (de 36 a 44) y una disminución de las de clase E (de 13 a 5) respecto a la evaluación con EMS

Multi-year particle fluxes in Kongsfjorden, Svalbard

Abstract. High-latitude regions are warming faster than other areas due to reduction of snow cover and sea ice loss and changes in atmospheric and ocean circulation. The combination of these processes, collectively known as polar amplification, provides an extraordinary opportunity to document the ongoing thermal destabilisation of the terrestrial cryosphere and the release of land-derived material into the aquatic environment. This study presents a 6-year time series (2010–2016) of physical parameters and particle fluxes collected by an oceanographic mooring in Kongsfjorden (Spitsbergen, Svalbard). In recent decades, Kongsfjorden has been experiencing rapid loss of sea ice coverage and retreat of local glaciers as a result of the progressive increase in ocean and air temperatures. The overarching goal of this study was to continuously monitor the inner fjord particle sinking and to understand to what extent the temporal evolution of particulate fluxes was linked to the progressive changes in both Atlantic and freshwater input. Our data show high peaks of settling particles during warm seasons, in terms of both organic and inorganic matter. The different sources of suspended particles were described as a mixing of glacier carbonate, glacier siliciclastic and autochthonous marine input. The glacier releasing sediments into the fjord was the predominant source, while the sediment input by rivers was reduced at the mooring site. Our time series showed that the seasonal sunlight exerted first-order control on the particulate fluxes in the inner fjord. The marine fraction peaked when the solar radiation was at a maximum in May–June while the land-derived fluxes exhibited a 1–2-month lag consistent with the maximum air temperature and glacier melting. The inter-annual time-weighted total mass fluxes varied by 2 orders of magnitude over time, with relatively higher values in 2011, 2013, and 2015. Our results suggest that the land-derived input will remarkably increase over time in a warming scenario. Further studies are therefore needed to understand the future response of the Kongsfjorden ecosystem alterations with respect to the enhanced release of glacier-derived material

Sinking diatom assemblages as a key driver for deep carbon and silicon export in the Scotia Sea (Southern Ocean)

Physical and biogeochemical processes in the Southern Ocean are fundamental for modulating global climate. In this context, a process-based understanding of how Antarctic diatoms control primary production and carbon export, and hence global ocean carbon sequestration, has been identified as a scientific priority. Here we use novel sediment trap observations in combination with a data-assimilative ocean biogeochemistry model (ECCO-Darwin) to understand how environmental conditions trigger diatom ecology in the iron-fertilized southern Scotia Sea. We unravel the role of diatoms assemblage in controlling the biogeochemistry of sinking material escaping from the euphotic zone, and discuss the link between changes in upper-ocean environmental conditions and the composition of settling material exported from the surface to 1,000 m depth from March 2012 to January 2013. The combined analysis of in situ observations and model simulation suggests that an anomalous sea-ice episode in early summer 2012–2013 favored (via restratification due to sea-ice melt) an early massive bloom of Corethron pennatum that rapidly sank to depth. This event drove high biogenic silicon to organic carbon export ratios, while modulating the carbon and nitrogen isotopic signals of sinking organic matter reaching the deep ocean. Our findings highlight the role of diatom ecology in modulating silicon vs. carbon sequestration efficiency, a critical factor for determining the stoichiometric relationship of limiting nutrients in the Southern Ocean.CTM2009-08287-E/ANT, CTM2011-14056E/ANT, SGR 315 2017info:eu-repo/semantics/publishedVersio

Retinal thickness study with optical coherence tomography in patients with diabetes

To quantitatively assess retinal thickness by optical coherence tomography (OCT) in normal subjects and patients with diabetes. This study was intended to determine which retinal thickness value measured with OCT best discriminates between diabetic eyes, with and without macular edema. METHODS: OCT retinal thickness was measured by a manual technique in a total of 26 healthy volunteers (44 control eyes) and 85 patients with diabetes (148 eyes) with the clinical diagnosis of no diabetic retinopathy (45 eyes), nonproliferative diabetic retinopathy without clinically significant macular edema (CSME; 54 eyes), proliferative diabetic retinopathy without CSME (21 eyes), and 28 eyes with diabetic retinopathy with CSME. Independent predictors of the presence of CSME were quantified by using univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) curves were generated to evaluate and compare the predictor variables. The correlation of retinal thickness measurements and visual acuity was calculated. RESULTS: There were statistically significant differences in foveal thickness between control eyes and all the other eye groups (P = 0.001). Diabetic eyes with CSME had a statistically significant greater thickness in each of the areas compared with the other groups. In a multivariate logistic regression model, foveal thickness was a strong and independent predictor of CSME (odds ratio [OR], 1.037; 95% confidence interval [CI] 1.02-1.05). The area under the ROC curve of this predictor variable was 0.94 (P = 0.001). For a cutoff point of 180 microm, the sensitivity was 93%, and specificity was 75%. Foveal thickness correlated with visual acuity in a log minimum angle of resolution (logMAR) scale (Spearman's rho = 0.9, P = 0.001). CONCLUSIONS: These results suggest that foveal thickening over 180 microm measured by OCT may be useful for the early detection of macular thickening and may be an indicator for a closer follow-up of the patient with diabetes

Journals’ policies of storage and reuse of raw research data and their impact in five scientific areas

Analisys of journals' policies about storage and re-use of raw research data

Validity of a self-reported diagnosis of depression among participants in a cohort study using the Structured Clinical Interview for DSM-IV (SCID-I).

Abstract Background: Depression assessment in population studies is usually based on depressive symptoms scales. However, the use of scales could lead to the choice of an arbitrary cut-off point depending on the sample characteristics and on the patient diagnosis. Thus, the use of a medical diagnosis of depression could be a more appropriate approach. Objective: To validate a self-reported physician diagnosis of depression using the Structured Clinical Interview for DSM-IV (SCID-I) as Gold Standard and to assess the factors associated to a valid self-reported diagnosis. Methods: The SUN Project is a cohort study based on university graduates followed-up through postal questionnaires. The response to the question included in the questionnaire: Have you ever been diagnosed of depression by a physician? was compared to that obtained through the SCID-I applied by a psychiatrist or a clinical psychologist. The percentages of confirmed depression and non-depression were assessed for the overall sample and according to several characteristics. Logistic regression models were fitted to ascertain the association between different factors and a correct classification regarding depression status. Results: The percentage of confirmed depression was 74.2%; 95% confidence interval (95% CI) =63.3-85.1. Out of 42 participants who did not report a depression diagnosis in the questionnaire, 34 were free of the disease (%confirmed non-depression=81.1%; 95% CI=69.1- 92.9). The probability of being a true positive was higher among ex- smokers and non-smokers and among those overweight or obese but the differences were not statistically significant. Conclusion: The validity of a self-reported diagnosis of depression in the SUN cohort is adequate. Thus, this question about depression diagnosis could be used in further investigations regarding this disease in this graduate cohort study