122 research outputs found

    The 2011 October Draconids outburst-I. Orbital elements, meteoroid fluxes and 21P/Giacobini-Zinner delivered mass to Earth

    Get PDF
    On 2011 October 8, the Earth crossed the dust trails left by comet 21P/Giacobini-Zinner during its 19th and 20th century perihelion approaches with the comet being close to perihelion. The geometric circumstances of that encounter were thus favourable to produce a meteor storm, but the trails were much older than in the 1933 and 1946 historical encounters. As a consequence the 2011 October Draconid display exhibited several activity peaks with Zenithal Hourly Rates of about 400 meteors h-1. In fact, if the display had not been forecasted, it could have passed almost unnoticed as was strongly attenuated for visual observers due to the Moon. This suggests that most meteor storms of a similar nature could have passed historically unnoticed under unfavourable weather and Moon observing conditions. The possibility of obtaining information on the physical properties of cometary meteoroids penetrating the atmosphere under low geocentric velocity encounter circumstances motivated us to set up a special observing campaign. Added to the Spanish Fireball Network wide-field all-sky and CCD video monitoring, other high-sensitivity 1/2 arcsec black and white CCD videocameras were attached to the modified medium-field lenses for obtaining high-resolution orbital information. The trajectory, radiant and orbital data of October 16 Draconid meteors observed at multiple stations are presented. The results show that the meteors appeared from a geocentric radiant located at α = 263.0 ± 0°.4 and δ =+55.3 ± 0°.3 that is in close agreement with the radiant predicted for the 1873-1894 and the 1900 dust trails. The estimated mass of material from 21P/Giacobini-Zinner delivered to Earth during the 6 h outburst was around950 ±150 kg

    Orbits and emission spectra from the 2014 Camelopardalids

    Get PDF
    We have analyzed the meteor activity associated with meteoroids of fresh dust trails of Comet 209P/LINEAR, which produced an outburst of the Camelopardalid meteor shower (IAU code #451, CAM) in May 2014. With this aim, we have employed an array of high-sensitivity CCD video devices and spectrographs deployed at 10 meteor observing stations in Spain in the framework of the Spanish Meteor Network (SPMN). Additional meteoroid flux data were obtained by means of two forward-scatter radio systems. The observed peak zenithal hourly rate (ZHR) was much lower than expected, of around 20 meteors h-1. Despite of the small meteor flux in the optical range, we have obtained precise atmospheric trajectory, radiant and orbital information for 11 meteor and fireball events associated with this stream. The ablation behaviour and low tensile strength calculated for these particles reveal that Camelopardalid meteoroids are very fragile, mostly pristine aggregates with strength similar to that of the Orionids and the Leonids. The mineral grains seem to be glued together by a volatile phase. We also present and discuss two unique emission spectra produced by two Camelopardalid bright meteors. These suggest a non-chondritic nature for these particles, which exhibit Fe depletion in their composition.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society on Sept. 22, 201

    Panorámica actual de las especies no indígenas marinas en el mar Cantábrico y Atlántico adyacente (NO-N de la península Ibérica): primera aproximación a la Directiva Marco de Estrategias Marinas en la demarcación noroeste

    Get PDF
    Simposio Ibérico de Estudios de Biología Marina (18º. 2014. Gijón (España))La introducción de especies invasoras no indígenas es un problema cada vez más común a escala mundial, siendo considerado una de mayores amenazas para la conservación de la biodiversidad de todo el planeta. Estas invasiones biológicas causan graves problemas ecológicos y en muchos casos ocasionan también importantes pérdidas a la economía local. La gravedad y el alcance de los impactos generados por las especies invasoras es tal, que en los últimos años ha trascendido del ámbito científico al político-social, siendo considerado como uno de los descriptores de la calidad ambiental en la Directiva Marco de la Estrategia Marina (MSFD 2008/56/EC). A pesar de la envergadura y repercusión de este problema, el estudio de las especies invasoras en aguas de la península Ibérica no ha sido abordado hasta fechas muy recientes, estando en su mayoría centrado en el ámbito continental de los ecosistemas dulceacuícolas y en el ámbito marino de la cuenca mediterránea de la península. Para las costas noratlánticas españolas(las cuales constituyen la demarcación noroeste de la Directiva Marco de la Estrategia Marina) los datos existentes son bastante escasos y sobre todo dispersos, siendo también en muchos casos de afiliación taxonómica dudosa. En este trabajo se presenta la primera revisión actualizada de las especies marinas reportadas como no indígenas (exóticas, no autóctonas, alóctonas o “alien”) ocriptogénicas para el mar Cantábrico y el Atlántico adyacente (costas de Galicia) hasta la actualidad; incluyendo también nuevas adiciones procedentes de los muestreos realizadosen las costas cantábricas y atlántico-gallegas entre los años 2010 y 2014. El área de estudio fue dividida en cuatro zonas (A-D) de Oeste a Este. En esta revisión no se reconocen como alóctonosy/o criptogénicosalgunos taxones previamente reportados como tales, ya que según nuestro criterio se tratan de especies nativas y/o especies que están extendiendo sus rangos de distribución de forma natural, en muchos casos como consecuencia de los fenómenos de calentamiento global. Se listan un total de 287 taxones considerados como no indígenas y/o criptogénicos para el área de estudio, constituyendo estos últimos aproximadamente un tercio del total (92 taxones). Para las taxones alóctonos(195), se ha seguido la clasificación de Zenetoset al. basada en el grado de invasión de las mismas. Las especies consideradas como “casuales” representaron aproximadamente una quinta parte del total (17%), mientras que las especies “establecidas” constituyeron algo menos de la mitad (41%). Finalmente, alrededor de un 6% de los taxones recogidos (17) se categorizaron como “invasores” para las aguas objeto de estudio. En función de las zonas geográficas en las que fue dividida el área de estudio, la gran mayoría de las especies (78%) fueron detectadas para una sola zona; un 21% lo fueron para al menos dos zonas; un 11% para tres y sólo un 6% de las especies fueron detectadas en las cuatro zonas (formando parte de éstas, 10 de las especies consideradas “invasoras”). Taxonómicamente, los filos con un mayor número de especies introducidas son los moluscos y los anélidos, agrupando, cada uno de ellos, un 21% del total de especies; seguidos del grupo de las algas rojas (16%) y de los artrópodos (14%). Otros filos que representan porcentajes mucho menores son los cnidarios (7%), los briozoos (5%), las algas pardas (4%), las ascidias (4%), los poríferos (3%), las algasverdes (2%), los gusanos nemertinos (<1%) y los equinodermos (<1%). El filo con mayor número de especies consideradas como “invasoras” es el grupo las algas rojas con 7 especies

    The granite and glacial landscapes of the Peneda-Gerês National Park

    Get PDF
    Granite and glacial landforms are presented as the main geomorphological landscape features of the Peneda-Gerês National Park. The park was established in 1971 and it is the only national park and most important protected area in Portugal. The aesthetic attractiveness is supported mainly by the distinct granite landscape of the Gerês and Peneda Mountains, where the post-orogenic Variscan Gerês gran- ite facies occurs. The rugged relief is poorly covered by vegetation, differentiating it from the surrounding moun- tainous areas and the most distinctive landforms are bornhardts, locally named as “medas”. Typical glacial landforms, such as U-shaped valleys, cirques and moraines, express the sheltered character of a low-altitude glaciation, which is of great significance in the context of the Pleistocene glaciation in Southern Europe.This work is co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Inter nacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145- FEDER-007690 and Portuguese national funds pro vided by Fundação para a Ciência e Tecnologi

    Clinical experience with integrase inhibitors in HIV-2-infected individuals in Spain.

    Get PDF
    Background: HIV-2 is a neglected virus despite estimates of 1–2 million people being infected worldwide. The virus is naturally resistant to some antiretrovirals used to treat HIV-1 and therapeutic options are limited for patients with HIV-2. Methods: In this retrospective observational study, we analysed all HIV-2-infected individuals treated with inte- grase strand transfer inhibitors (INSTIs) recorded in the Spanish HIV-2 cohort. Demographics, treatment modal- ities, laboratory values, quantitative HIV-2 RNA and CD4 counts as well as drug resistance were analysed. Results: From a total of 354 HIV-2-infected patients recruited by the Spanish HIV-2 cohort as of December 2017, INSTIs had been given to 44, in 18 as first-line therapy and in 26 after failing other antiretroviral regimens. After a median follow-up of 13 months of INSTI-based therapy, undetectable viraemia for HIV-2 was achieved in 89% of treatment-naive and in 65.4% of treatment-experienced patients. In parallel, CD4 gains were 82 and 126cells/mm3, respectively. Treatment failure occurred in 15 patients, 2 being treatment-naive and 13 treatment-experienced. INSTI resistance changes were recognized in 12 patients: N155H (5), Q148H/R (3), Y143C/G (3) and R263K (1). Conclusions: Combinations based on INSTIs are effective and safe treatment options for HIV-2-infected individ- uals. However, resistance mutations to INSTIs are selected frequently in failing patients, reducing the already limited treatment options

    Definition of a temporal distribution index for high temporal resolution precipitation data over Peninsular Spain and the Balearic Islands: the fractal dimension; and its synoptic implications

    Get PDF
    Precipitation on the Spanish mainland and in the Balearic archipelago exhibits a high degree of spatial and temporal variability, regardless of the temporal resolution of the data considered. The fractal dimension indicates the property of self-similarity, and in the case of this study, wherein it is applied to the temporal behaviour of rainfall at a fine (10-min) resolution from a total of 48 observatories, it provides insights into its more or less convective nature. The methodology of Jenkinson & Collison which automatically classifies synoptic situations at the surface, as well as an adaptation of this methodology at 500 hPa, was applied in order to gain insights into the synoptic implications of extreme values of the fractal dimension. The highest fractal dimension values in the study area were observed in places with precipitation that has a more random behaviour over time with generally high totals. Four different regions in which the atmospheric mechanisms giving rise to precipitation at the surface differ from the corresponding above-ground mechanisms have been identified in the study area based on the fractal dimension. In the north of the Iberian Peninsula, high fractal dimension values are linked to a lower frequency of anticyclonic situations, whereas the opposite occurs in the central region. In the Mediterranean, higher fractal dimension values are associated with a higher frequency of the anticyclonic type and a lower frequency of the advective type from the east. In the south, lower fractal dimension values indicate higher frequency with respect to the anticyclonic type from the east and lower frequency with respect to the cyclonic type

    After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission

    Get PDF
    NASA’s Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ∼10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos’s response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor β, showing that a particular direction-specific β will be directly determined by the DART results, and that a related direction-specific β is a figure of merit for a kinetic impact mission. The DART β determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos’s near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction

    New GOLD classification: Longitudinal data on group assignment

    Get PDF
    Rationale: Little is known about the longitudinal changes associated with using the 2013 update of the multidimensional GOLD strategy for chronic obstructive pulmonary disease (COPD). Objective: To determine the COPD patient distribution of the new GOLD proposal and evaluate how this classification changes over one year compared with the previous GOLD staging based on spirometry only. Methods: We analyzed data from the CHAIN study, a multicenter observational Spanish cohort of COPD patients who are monitored annually. Categories were defined according to the proposed GOLD: FEV1%, mMRC dyspnea, COPD Assessment Test (CAT), Clinical COPD Questionnaire (CCQ), and exacerbations-hospitalizations. One-year follow-up information was available for all variables except CCQ data. Results: At baseline, 828 stable COPD patients were evaluated. On the basis of mMRC dyspnea versus CAT, the patients were distributed as follows: 38.2% vs. 27.2% in group A, 17.6% vs. 28.3% in group B, 15.8% vs. 12.9% in group C, and 28.4% vs. 31.6% in group D. Information was available for 526 patients at one year: 64.2% of patients remained in the same group but groups C and D show different degrees of variability. The annual progression by group was mainly associated with one-year changes in CAT scores (RR, 1.138; 95%CI: 1.074-1.206) and BODE index values (RR, 2.012; 95%CI: 1.487-2.722). Conclusions: In the new GOLD grading classification, the type of tool used to determine the level of symptoms can substantially alter the group assignment. A change in category after one year was associated with longitudinal changes in the CAT and BODE index

    Prevalence of high-risk HPV genotypes, categorised by their quadrivalent and nine-valent HPV vaccination coverage, and the genotype association with high-grade lesions

    Get PDF
    BACKGROUND: The new nine-valent vaccine against human papillomavirus (HPV) includes the four HPV genotypes (6, 11, 16, and 18) that are targeted by the older quadrivalent HPV vaccine, plus five additional oncogenic types (31, 33, 45, 52, and 58) remain significantly associated with high grade lesions. We aimed to determine the prevalence of high-risk HPV genotypes in unvaccinated subjects and the association of these genotypes with the incidence of high-grade lesions. We also assessed which, if either, of these two HPV vaccines could have prevented these cases. METHODS: This cross-sectional study, conducted from 4 January 2010 to 30 December 2011, was composed of 595 women attending the Hospital General Universitario de Elche (Spain) gynaecology department who were positively screened for opportunistic cervical cancer by pap smears and HPV detection during a routine gynaecological health check. The pap smear results were classified using the Bethesda system. HPV genotyping was performed with the Linear Array HPV genotyping test, and viruses were classified by the International Agency for Research on Cancer assessment of HPV carcinogenicity. Odds ratios (ORs) with their 95% confidence intervals (95% CI) were estimated by logistic regression, adjusting for age and immigrant status. The prevented fraction among those exposed (PFe-adjusted) was determined as a measure of impact. RESULTS: At least one of the additional five high-risk HPV genotypes present in the nine-valent HPV vaccine was detected in 20.5% of subjects. After excluding women with genotype 16 and/or 18 co-infection, high-risk genotypes (31, 33, 45, 52, and 58) were associated with a higher risk of intraepithelial lesion or malignancy: adjusted OR?=?3.51 (95% CI, 1.29-9.56), PFe-adjusted?=?0.72 (95% CI, 0.22-0.90). Genotypes that are still non-vaccine-targeted were detected in 17.98% of the women, but these were not significantly associated with high-grade lesions. CONCLUSION: The greater protection of the nine-valent HPV vaccine is likely to have a positive impact because, in the absence of genotype 16 or 18 infection, these five genotypes on their own remained significantly associated with high-grade lesions

    Polarimetry of binary systems: polars, magnetic CVs, XRBs

    Full text link
    Polarimetry provides key physical information on the properties of interacting binary systems, sometimes difficult to obtain by any other type of observation. Indeed, radiation processes such as scattering by free electrons in the hot plasma above accretion discs, cyclotron emission by mildly relativistic electrons in the accretion shocks on the surface of highly magnetic white dwarfs and the optically thin synchrotron emission from jets can be observed. In this review, I will illustrate how optical/near-infrared polarimetry allows one to estimate magnetic field strengths and map the accretion zones in magnetic Cataclysmic Variables as well as determine the location and nature of jets and ejection events in X-ray binaries.Comment: 26 pages, 16 figures; to be published in Astrophysics and Space Science Library 460, Astronomical Polarisation from the Infrared to Gamma Rays, Editors: Mignani, R., Shearer, A., S{\l}owikowska, A., Zane,
    corecore