175 research outputs found

    Spatial variation of trace elements in the peri-urban soil of Madrid

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    Purpose The peri-urban region to the south east of Madrid contains a mixture of housing, manufacturing industry and farming, some of which disperse metals, in particular cadmium, copper, lead, and zinc, into the soil. We have mapped the concentrations of these elements and identified the major influences on their distributions. Material and methods We sampled the topsoil at 125 sites across 1,050 km2 of peri-urban land to the south east of the city on two grids, one nested inside the other. At each site, we measured the current contents of the four trace elements in the soil. We used robust geostatistical methods to model the complex spatial distributions of the data as mixtures of fixed and random effects. The empirical best linear unbiased predictor was used to map the elements. Site descriptors (lithology, land cover, cultivation, relief, erosion, and stoniness) were then included as covariates to identify significant effects on trace element concentrations. Results and discussion The complex spatial distributions of the elements seem to arise from several sources. The concentrations generally increase from southeast to northwest, i.e.;with increasing proximity to Madrid itself, the main potential source of pollution. This pattern is clear for lead and similar for copper and zinc, though with "hot spots" at or near industrial sites. The spatial pattern of cadmium is more complex and depends on varied lithology, industry, and land use such as irrigation and cultivation. In general, the concentrations of the four elements appear to decrease with increases in stoniness and erosion, and to be largest on the valley floors. Conclusions Robust geostatistical methods enabled us to analyze and map the complex patterns of spatial variation of trace elements in a peri-urban region of Madrid. They show that distance to the city center, lithology, manufacturing industry, and cultivation all play their parts in loading the soil with lead, copper, zinc, and cadmium. In the event, none of the metals has yet exceeded the legislative thresholds, but some concentrations are already substantially greater than would arise from natural sources, especially closest to Madrid itself. © 2013 The Author(s)

    A mid-term astrometric and photometric study of trans-Neptunian object (90482) Orcus

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    From time series CCD observations of a fixed and large star field that contained the binary trans-Neptunian object (90482) Orcus (formerly 2004 DW), taken during a period of 33 days, we have been able to derive high-precision relative astrometry and photometry of the Orcus system with respect to background stars. The right ascension residuals of an orbital fit to the astrometric data revealed a periodicity of 9.7 ± 0.3 days, which is what one would expect to be induced by the known Orcus companion (Vanth). The residuals are also correlated with the theoretical positions of the satellite with regard to the primary. We therefore have revealed the presence of Orcus’ satellite in our astrometric measurements, although the residuals in declination did not show the expected variations. The oscillation in the residuals is caused by the photocenter motion of the combined Orcus plus satellite system around the barycenter along an orbital revolution of the satellite. The photocenter motion is much larger than the motion of Orcus around the barycenter, and we show here that detecting some binaries through a carefully devised astrometric technique might be feasible with telescopes of moderate size. We discuss the prospects for using the technique to find new binary trans-Neptunian objects (TNOs) and to study already known binary systems with uncertain orbital periods. We also analyzed the system’s mid-term photometry in order to determine whether the rotation could be tidally locked to the satellite’s orbital period. We found that a photometric variability of 9.7 ± 0.3 days is clear in our data, and is nearly coincident with the orbital period of the satellite. We believe this variability might be induced by the satellite’s rotation. In our photometry there is also a slight hint for an additional very small variability in the 10 h range that was already reported in the literature. This short-term variability would indicate that the primary is not tidally locked and therefore the system would not have reached a double synchronous state. Implications for the basic physical properties of the primary and its satellite are discussed. From angular momentum considerations we suspect that the Orcus satellite might have formed from a rotational fission. This requires that the mass of the satellite would be around 0.09 times that of the primary, close to the value that one derives by using an albedo of 0.12 for the satellite and assuming equal densities for both the primary and secondary.Facultad de Ciencias Astronómicas y Geofísica

    A mid-term astrometric and photometric study of Trans-Neptunian Object (90482) Orcus

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    From CCD observations of a fixed and large star field that contained the binary TNO Orcus, we have been able to derive high-precision relative astrometry and photometry of the Orcus system with respect to background stars. The RA residuals of an orbital fit to the astrometric data revealed a periodicity of 9.7+-0.3 days, which is what one would expect to be induced by the known Orcus companion. The residuals are also correlated with the theoretical positions of the satellite with regard to the primary. We therefore have revealed the presence of Orcus' satellite in our astrometric measurements. The photocenter motion is much larger than the motion of Orcus around the barycenter, and we show here that detecting some binaries through a carefully devised astrometric technique might be feasible with telescopes of moderate size. We also analyzed the system's mid-term photometry to determine whether the rotation could be tidally locked to the satellite's orbital period. We found that a photometric variability of 9.7+-0.3 days is clear in our data, and is nearly coincident with the orbital period of the satellite. We believe this variability might be induced by the satellite's rotation. There is also a slight hint for an additional small variability in the 10 hr range that was already reported in the literature. This short-term variability would indicate that the primary is not tidally locked and therefore the system would not have reached a double synchronous state. Implications for the basic physical properties of the primary and its satellite are discussed. From angular momentum considerations we suspect that the Orcus satellite might have formed from a rotational fission. This requires that the mass of the satellite would be around 0.09 times that of the primary, close to the value that one derives by using an albedo of 0.12 for the satellite and assuming equal densities for both objects.Comment: in Press at A&

    Correlation between the findings in the first post-transplantation Renogram and the allograft renal function twelve months after surgery

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    EP-061 Aim/Introduction: To study the correlation between findings in the first renogram post-trasplantation, and the evolution of the renal function of the graft twelve months after surgery. Materials and Methods: 20-minute duration renogram with [99mTc]Tc-MAG3, performed in the first 72 hours post-kidney transplantation, of patients attended at the Nuclear Medicine Service between January-December of 2018 are reviewed, extracting: a) the concentration angle (CA) that measures the inclination of the ascent section of the concentration phase with respect to the vertical axis (cutoff thershold <40° vs =40°); b) the time, in minutes (Tmax), at which the maximum concentration occurs (<10 vs =10min); and c) the percentage of cortical retention (CR) at the end of the study (<80% vs =80%). These 3 parameters are correlated with renal function at 12 months post-transplantation, through the need or not of dialysis. Results: A total of 62 renograms were obtained, excluding 7 due to death as a result of intercurrent diseases and 2 due to vascular complications and graft loss, before the first year after surgery. 53 patients, 15 female and 38 male, aged between 20-80 years, were included in the analysis. Functional failure (dialysis) of the graft one year after the transplantation ocurred in 15% (8/53). In patients with CA =40° the probability of failure was 28% (5/18) and in CA <40° 8.6% (3/35), with relative risk (RR) of 3.2. 7/34 (20, 6%) patients incluided in the group with Tmax =10 min were on dialysis one-year after, unlike just 1/19 (5, 3%) if Tmax<10min (RR 3, 8). Among the 37 patients with CR =80%, 8/37 (22%) were dialyzed one year after, while none of the 16 in the group of patients with CR <80% (0% probability if CR <80%). The matching of parameteres CA =40°, Tmax =10 min and CR =80% together do not improve the prediction of dialysis one year after (27%, 5/18). Conclusion: 1. Renogram parameters 72 hours post-transplantation, such as concentration phase angle =40°, time at maximun concentration =10min and percentage of cortical retention =80%, allow recognize a group of patients with greater probability of needing dialysis in the first year after surgery, but they do not are capable of indentify in which specific patients it will occur. 2. The parameter that best predicts the viability of the graft is cortical retention <80%

    Observation of light echoes around very young stars

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    The goal of the paper is to present new results on light echoes from young stellar objects. Broad band CCD images were obtained over three months at one-to-two week intervals for the field of NGC 6726, using the large field-of-view remotely-operated telescope on top of Cerro Burek. We detected scattered light echoes around two young, low-amplitude, irregular variable stars. Observations revealed not just one, but multiple light echoes from brightness pulses of the T Tauri star S CrA and the Herbig Ae/Be star R CrA. Analysis of S CrA's recurring echoes suggests that the star is located 138 +/- 16 pc from Earth, making these the closest echoes ever detected. The environment that scatters the stellar light from S CrA is compatible with an incomplete dust shell or an inclined torus some 10,000 AU in radius and containing \sim 2×1032 \times 10^{-3} M_{\sun} of dust. The cause of such concentration at \sim 10,000AU from the star is unknown. It could be the remnant of the envelope from which the star formed, but the distance of the cloud is remarkably similar to the nominal distance of the Oort cloud to the Sun, leading us to also speculate that the dust (or ice) seen around S CrA might have the same origin as the Solar System Oort cloud.Comment: A&A, in press Received: 16 March 2010 / Accepted: 01 June 201

    Actualización en técnicas continuas de reemplazo renal

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    El fracaso renal agudo afecta a un 25% de los pacientes hospitalizados en las unidades de cuidados intensivos. A pesar de los avances tecnológicos, la mortalidad de estos pacientes sigue siendo elevada debido a las complicaciones asociadas. Uno de los tratamientos del fracaso renal agudo son las técnicas continuas de reemplazo renal ya que permiten tratar las complicaciones y disminuir la mortalidad. El conocimiento y la habilidad de la enfermera en relación con estas técnicas serán decisivos para el éxito de la terapia. Para ello, la formación y la experiencia de la enfermera son el componente clave. El presente artículo tiene como objetivo actualizar los conocimientos sobre las técnicas continuas de reemplazo renal. Para ello, se realiza una revisión de los principios físico-químicos, como la difusión y la convección, entre otros, una descripción de las modalidades de las técnicas continuas de reemplazo renal, una presentación de los principales accesos vasculares y una descripción de los cuidados enfermeros y de las complicaciones relacionadas con las técnicas utilizadas

    Analysis of results of effective dose estimation obtained from RADAR 2017 dose assessment model for nuclear medicine procedures

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    EP-296 Aim/Introduction: To analyze the results of effective dose (E) estimation of the most frequent procedures using photon emitters in Nuclear Medicine, obtained from RADAR 2017 dose assessment model. To compare these results with those obtained from ICRP 128 (2015) recommendations, and to assess how using each dose assessment model can change E results. Materials and Methods: E estimation data was collected from photon emitter procedures performed during the last year in our department, obtained from RADAR 2017 dose estimation model for age groups: = 1 year old; >1-5 years old ; >5- 10 years old, >10- 15 years old and adults. Injected activity was the one recommended by international guidelines and EANM Pediatric and Dosimetry Committees. Hybrid exams (SPECT / CT) and procedures for which there is no RADAR 2017 dosimetry estimation were excluded. Results for (E) were compared with those obtained by using ICRP 128 (2015) recommendations. Results: With RADAR 2017 dose evaluation model we obtained a lower mean value of E on most of the procedures that were analyzed, being significantly lower for Renogram, Renal scintigraphy on >10-15 years old, Thyroid scintigraphy, Meckel’s scan and Bone Scan (0.12 to 1.16 mSv, 25% to 67%). Brain perfusion and Renal scintigraphy on ages under 10 obtained a significantly greater difference for E (0.33 to 2.85 mSv, 26% to 29%). Conclusion: These results are an updated collection of estimated E values for photon-emitting radiopharmaceuticals commonly used in Nuclear Medicine, considering RADAR 2017 dose assessment model compared to ICRP 128) recommendations. Methodological changes on estimation lead to lower E for most of diagnostic procedures using photon emitters, this is of special interest for patients undergoing repeated ionizing radiation (dosimetry history)

    Practical update of the Recommendations Published by the Psoriasis Group of the Spanish Academy of Dermatology and Venereology (GPS) on the Treatment of Psoriasis with Biologic Therapy. Part 1. Concepts and General Management of Psoriasis with Biologic Therapy

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    Justificación y objetivos La aprobación de un gran número de nuevos fármacos en los últimos años y los cambios en el paradigma de tratamiento de la psoriasis hacen recomendable un nuevo documento de recomendaciones del GPS para el tratamiento de la psoriasis moderada-grave. Metodología Para la elaboración del consenso se siguió la metodología de grupos nominales, con ayuda de una scoping review. Tras designar a un coordinador, se seleccionó un grupo de integrantes del GPS. El coordinador definió los objetivos y puntos clave del documento y, con ayuda de un documentalista, se realizó una scoping review incluyendo datos de Medline, Embase y Cochrane Library (hasta enero del 2021). Se seleccionaron revisiones sistemáticas, metaanálisis y ensayos clínicos no incluidos en las mismas, así como estudios de calidad en vida real. Se revisaron otras guías de práctica clínica y documentos de consenso nacionales e internacionales sobre el manejo de la psoriasis moderada-grave. El coordinador generó una serie de recomendaciones preliminares que fueron evaluadas y modificadas en una reunión de grupo nominal. Tras varios procesos de revisión, que incluyeron la revisión externa por parte de los miembros del GPS, se redactó el documento definitivo. Resultados En el documento se incluyen principios generales sobre el tratamiento de los pacientes con psoriasis moderada-grave, la definición de objetivos terapéuticos y los criterios de indicación y selección de tratamiento tanto en primera como en sucesivas líneas terapéuticas de fármacos biológicos. Se abordan asimismo cuestiones prácticas como el fracaso terapéutico o el mantenimiento de la respuesta.Background and objectives A new, updated AEDV Psoriasis Group consensus document on the treatment of moderate to severe psoriasis was needed owing to the approval, in recent years, of a large number of new drugs and changes in the treatment paradigm. Methodology The consensus document was developed using the nominal group technique and a scoping review. First, a designated coordinator selected a group of Psoriasis Group members for the panel. The coordinator defined the objectives and key points for the document and, with the help of a documentalist, conducted a scoping review of articles in Medline, Embase, and the Cochrane Library up to January 2021. The review included systematic reviews and meta-analyses as well as clinical trials not included in those studies and high-quality real-world studies. National and international clinical practice guidelines and consensus documents on the management of moderate to severe psoriasis were also reviewed. Based on these reviews, the coordinator drew up a set of proposed recommendations, which were then discussed and modified in a nominal group meeting. After several review processes, including external review by other GPs members, the final document was drafted. Results The present guidelines include general principles for the treatment of patients with moderate to severe psoriasis and also define treatment goals and criteria for the indication of biologic therapy and the selection of initial and subsequent therapies. Practical issues, such as treatment failure and maintenance of response, are also addressed
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