566 research outputs found

    Characterisation and calibration of a scintillating fibre detector with > 4000 multi-anode photomultiplier channels

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    In the Kaos spectrometer at the Mainz Microtron a high-resolution coordinate detector for high-energy particles is operated. It consists of scintillating fibres with diameters of 4000 multi-anode photomultiplier channels. It is one of the most modern focal-plane detectors for magnetic spectrometers world-wide. To correct variations in the detection efficiency, caused by the different gains and the different optical transmittances, a fully automated off-line calibration procedure has been developed. The process includes the positioning of a radioisotope source alongside the detector plane and the automated acquisition and analysis of the detector signals. It was possible to characterise and calibrate each individual fibre channel with a low degree of human interaction.Comment: Nucl. Instrum. Meth. A (2012

    Using smart cards for authenticating in public services: A comparative study

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    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-19713-5_37Smart cards are well-known tamper-resistant devices, and as such they represent an excellent platform for implementing strong authentication. Many services requesting high levels of security rely on smart cards, which provide a convenient security token due to their portability. This contribution analyses two Spanish smart card deployments intended to be used for accessing eGoverment services, comparing their respective contents and capabilities.This work has been partially supported by Comunidad de Madrid (Spain) under the project S2013/ICE-3095-CM (CIBERDINE)

    Comparisons in Performance of Electromagnet and Permanent-Magnet Cylindrical Hall-Effect Thrusters

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    Three different low-power cylindrical Hall thrusters, which more readily lend themselves to miniaturization and low-power operation than a conventional (annular) Hall thruster, are compared to evaluate the propulsive performance of each. One thruster uses electromagnet coils to produce the magnetic field within the discharge channel while the others use permanent magnets, promising power reduction relative to the electromagnet thruster. A magnetic screen is added to the permanent magnet thruster to improve performance by keeping the magnetic field from expanding into space beyond the exit of the thruster. The combined dataset spans a power range from 50-350 W. The thrust levels over this range were 1.3-7.3 mN, with thruster efficiencies and specific impulses spanning 3.5-28.7% and 400-1940 s, respectively. The efficiency is generally higher for the permanent magnet thruster with the magnetic screen, while That thruster s specific impulse as a function of discharge voltage is comparable to the electromagnet thruster

    Osteonecrosis del platillo tibial interno: A propósito de dos casos

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    Presentamos dos casos de osteonecrosis idiomática del platillo tibial interno que aparecieron en mujeres. En ellas se dieron las características clínicas habituales de la enfermedad (inicio súbito de dolor intenso en rodilla sin traumatismo previo claramente diferenciado y marcada sensibilidad local en la zona interna de la rodilla) junto a radiografías iniciales normales ó con leves cambios degenerativos (gammagrafía ósea y/ó resonancia magnética nuclear.) En las dos pacientes el proceso evolucionó hacia una gonalgia intensa resistente a la medicación y con cambios degenerativos asociados y fue necesaria la implantación de sendas artroplastias totales de rodilla.We report two cases of osteonocrosis of the medial tibial plateau with typical symptoms (sudden onset of pain at the knee, and marked tenderness over the medial tibial plateau). Initial roentgenograms are within normal limits or showed mild degenerative joint changes, being necessary a magnetic resonance imaging to achieve a diagnosis. The two cases we report didn't follow the typical evolution of the process (which is self-limiting in a period of 6 to 12 months), being necessary in both of them, a total knee replacement

    Liberación de la patela en las artroplastias totales de rodilla: estudio gammagráfico

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    Se han realizado estudios gammagráficos en 20 pacientes intervenidos de artroplastia total cementada de rodilla. En 10 casos fue necesaria la liberación del alerón rotuliano externo y en otros 10 no se había indicado dicho gesto quirúrgico. En ningún paciente existía alteración evolutiva del aparato extensor. Los estudios gammagráficos se practicaron a los 12 meses del implante con el objeto de valorar la situación vascular de la rótula en ese momento. Se comparó, en la proyección lateral, la captación de la rótula en relación a la metáfisis distal del fémur homolateral. No hemos encontrado diferencias entre ambos grupos por lo que consideramos que la liberación patelar no produce un déficit vascular rotuliano a los 12 meses de la cirugía.Scintigraphic studies were performed in 20 patients with cemented total prosthesis of the knee. The patellar release was necessary in 10 cases. None of the patients developed knee extension deficits. Scintigraphic studies were performed 12 months after surgery in order to know the patellar blood supply at that moment. Patellar isotopic uptake was compared with the uptake at the distal metaphysis of the homolateral femur, at lateral projection. We haven't found any differences between both groups, so we consider that the patellar release doesn't make a less blood supply twelve months after surgery

    Dominance of the planktonic diatom Thalassiosira minima in recent summers in the Bahia Blanca Estuary, Argentina

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    The diatom Thalassiosira minima was first recorded in the Baha Blanca Estuary in 1992. In 19921993 it exhibited a broad seasonal occurrence. A recent survey (20062007) showed a seasonal appearance restricted mainly to summer together with a greater relative abundance within the phytoplankton. A close connection was found with warmer, more saline and highly turbid conditions experienced in recent summers in the estuary. Whether these changes will impact the estuary trophic dynamics remains an open question

    Aluminium and mineral stability in soils from the As Pontes region

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    [Resumen] Se estudian las fracciones de Al potencialmente liberable de la fase sólida (Al cambiable, potencial lábil y potencial máximo), las formas de Al presentes en disolución de suelo y los índices de saturación para ciertos minerales de Al (gibbsita, gibbsita microcristalina, caolinita, alunita, jurbanita y basaluminita), en horizontes A y B de suelos derivados de diferentes materiales de partida representativos de la zona de estudio (rocas graníticas, neises, esquistos, filit~s, sedimentos cuarzosos y rocas metabásicas). Los resultados muestran que los suelos de granito, filita y neis presentan los mayores niveles de Al cambiable, potencial lábil, potencial máximo y Al total en disolución; los suelos derivados de rocas metabásicas muestran importantes contenidos de Al potencial máximo y escasos nive~s de las formas más lábiles y Al total en disolución. Los esquistos presentan valores intermedios para estas formas de Al. Los índices de saturación mineral indican que, con independencia del material original y tipo de horizonte, un importante número de muestras se sitúan en el campo de la disolución para todos los minerales considerados. Cuando se dan condiciones de sobresaturación, la caolinita es el mineral más estable mientras que la gibbsita es el que más frecuentemente controla la actividad del AP+ en disolución.[Abstract] Al fractions susceptible to be liberated from the solid phase, Al forms in soil solutions and the saturation indexes for certain Al-minerals (gibbsite, microcristaline gibbsite, kaolinite, alunite, jurbanite and basalunite) are studied in the A and B horizonts of soils derived from different parent materials representative of the studied area (granitic rocks, gneisses, schists, phyllites, quarzous sediments and metabasic rocks). The results show that the soils from granite, phyllite and gneiss had the highest levels of exchangeable, labile potential, maximun potential. Al in the solid phase and total Al in soil solution; the soils derived from metabasic rocks showed high quantities of maximun potential Al and low levels of the most labile forms and total Al in solution. The schist displayed intermediate values for these Al forms. The mineral saturation indexes indicate that many samples, independendy of the parent material and horizon type, are situated in the disolution field for the minerals considered. When oversaturation conditions are produced, kaolinite is the most stable mineral and gibbsite the one that, most frequendy, controls AP+ activity in soludo

    Contra las interpretaciones simplistas de los resultados de los experimentos realizados en el aula

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    This paper is about the importance of the students' interpretation of experiments made in the school. Examples are given of the students' interpretations of specific activities, and possibles classroom strategies bases on these interpretations are suggestedS

    Single Cord Blood Combined with HLA-Mismatched Third Party Donor Cells: Comparable Results to Matched Unrelated Donor Transplantation in High-Risk Patients with Hematologic Disorders

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    AbstractMatched unrelated donor (MUD) transplantation is the first alternative in the absence of a matched sibling donor. For patients without a suitable adult donor, we have adopted the dual stem cell transplantation protocol consisting of cord blood (CB) in combination with CD34+ cells from a third party HLA-mismatched donor. We analyzed the outcomes of patients undergoing both procedures in a single center. Starting in 2004, a total of 20 patients with high-risk disease underwent 22 dual transplants and 25 patients underwent myeloablative MUD transplantation. The 30-day cumulative incidence of neutrophil engraftment was similar in both groups (91% and 95%), with a median time to engraftment of 14 and 16 days, respectively. Grade II-IV acute graft-versus-host disease was more frequent in the MUD group (40% versus 5%). Except for a tendency toward a higher incidence of viral hemorrhagic cystitis in the dual transplantation group, posttransplantation infectious events were comparable in the 2 groups. The 3-year cumulative incidence rates of relapse (41% versus 44%) and nonrelapse mortality (30% versus 25%) were similar in the MUD and dual transplantation cohorts. Estimated 3-year overall survival and disease-free survival were 47% and 41%, respectively, with no survival advantage for either group. In our experience, dual transplantation offers survival rates comparable to those from myeloablative MUD transplantation with similar nonrelapse mortality rates
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