143 research outputs found

    Worst cases for an one-hop high frequency link

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    The characterisation of a HF channel by means of monthly electron density profiles can be complemented with a detailed study of radio propagation «worst cases» on situations with extremes conditions of radiopropagation for a given period. These «worst cases» correspond to conditions that can be identified by means of cumulative distributions of the key parameter f0F2. In this paper, the main parameters of the HF channel: time delay, apogee, elevation angle and transmission frequency with mean and extreme conditions are analysed. The method used to characterise the ionospheric channel is based on ray-tracing techniques

    Standardization and performance evaluation of mononuclear cell cytokine secretion assays in a multicenter study

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    BACKGROUND: Cryopreservation of peripheral blood mononuclear cells has been used to preserve and standardize immunologic measurements for multicenter studies, however, effects of cryopreservation on cytokine responses are incompletely understood. In designing immunologic studies for a new multicenter birth cohort study of childhood asthma, we performed a series of experiments to determine the effects of two different methods of cryopreservation on the cytokine responses of cord and peripheral blood mononuclear cells. RESULTS: Paired samples of PBMC were processed freshly, or after cryopreservation in a Nalgene container (NC) or a controlled-rate freezer (CRF). Although there were some differences between the methods, cryopreservation inhibited PHA-induced IL-10 secretion and Der f 1-induced IL-2 secretion, and augmented PHA-induced IL-2 secretion and spontaneous secretion of TNF-α. In separate experiments, NC cryopreservation inhibited secretion of several cytokines (IL-13, IL-10, IFN-γ, TNF-α) by PHA-stimulated cord blood mononuclear cells. With the exception of PHA-induced IL-13, results from fresh and cryopreserved cord blood samples were not significantly correlated. Finally, in reproducibility studies involving processing of identical cell samples in up to 4 separate laboratories, variances in cytokine responses of fresh cells stimulated at separate sites did not exceed those in cryopreserved cells stimulated at a central site. CONCLUSION: Collectively, these studies indicate that cryopreservation can affect mononuclear cell cytokine response profiles, and that IL-10 secretion and antigen-induced responses may be especially vulnerable. These studies also demonstrate that mononuclear cell responses can be standardized for performance in a small number of laboratories for multicenter studies, and underscore the importance of measuring reproducibility and of testing whether cryopreservation techniques alter specific immunologic outcomes

    Experiencia inicial con la prótesis de despliegue rápido en posición aórtica Edwards Intuity

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    ResumenObjetivoDisponemos de una nueva clase de prótesis aórticas de despliegue rápido para tratamiento quirúrgico de la estenosis aórtica. Permitirían disminuir los tiempos quirúrgicos y facilitarían la cirugía mínimamente invasiva. Presentamos nuestra experiencia inicial con la válvula Edwards Intuity en el contexto del estudio multicéntrico Foundation.Pacientes y métodosEntre septiembre de 2012 y febrero de 2014 se implantaron 25 prótesis aórticas Edwards Intuity en 26 pacientes (77±4,3años; 52% varones). Veinticuatro (96%) fueron reemplazo valvular aislado, y 9 pacientes (36%) tuvieron abordaje mínimamente invasivo. Los pacientes fueron estudiados al alta, a los 3meses y al año de la intervención.ResultadosHubo éxito en el implante en el 96,2% de los pacientes (25/26). No hubo mortalidad hospitalaria. Seguimiento medio de 11±5,4meses, supervivencia acumulada del 96%. Un paciente falleció a los 11meses por un ictus isquémico. El tiempo medio de pinzamiento aórtico fue de 38,2±10,1min y el tiempo medio de circulación extracorpórea, de 62,4±11,1min. A los 3meses, el área valvular efectiva media fue de 1,70±0,42cm2. El 91% de los pacientes (23/25) estaban en grado funcionali en el seguimiento.ConclusionesEl implante de la válvula Edwards Intuity para el tratamiento de la estenosis aórtica ha sido factible, seguro y eficaz. Los tiempos de isquemia miocárdica y de circulación extracorpórea parecen reducirse en comparación con la cirugía valvular aórtica habitual. El comportamiento hemodinámico inicial de la prótesis Edwards Intuity es excelente.AbstractObjectiveA new class of rapid deployment prostheses is now available for surgical treatment of aortic stenosis. These prostheses offer the possibility of reducing the duration of cardiopulmonary bypass and aortic clamping times, and facilitate the use of minimally invasive surgery. We present our initial experience with the Edwards Intuity valve in the context of a multicentre Foundation study.Patients and methodsBetween September 2012 and February 2014, 25 Edwards Intuity valves were implanted in 26 patients (77±4.3years; 52% male). Twenty-four (96%) were isolated aortic valve replacement; a minimally invasive approach was used on 9 patients (36%). Patients were studied at discharge, three months, and one year after surgery.ResultsImplantation success rate was 96.2% (25/26). There was no hospital mortality. Mean follow-up of 11±5.54months, cumulative survival of 96%. One patient died eleven months after surgery due to ischaemic stroke. The mean aortic clamping time was 38.2±10.1minutes, and the mean cardiopulmonary bypass (CPB) time was 62.4±11.1minutes. In the echocardiography at 3months, the mean effective valve area was 1.70±0.42cm2, and 91% of patients (23/25) were in functional classi NYHA at follow-up.ConclusionsThe implantation of the Edwards Intuity valve for surgical treatment of aortic stenosis has shown to be feasible, safe and effective. Times of myocardial ischaemia and extracorporeal circulation appear to be reduced compared with normal aortic valve surgery. The initial haemodynamic performance of the Edwards Intuity prosthesis is excellent

    Parallax in “Pi of the Sky” project

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    The main goal of the “Pi of the Sky” project is search for optical transients (OTs) of astrophysical origin, in particular those related to gamma-ray bursts (GRBs). Since March 2011 the project has two running observatories: one in northern Chile and the other one insouthern Spain. This allows for regular observations of a common sky fields, visible from both observatories which are scheduled usually 1–2 h per night. In such a case, the on-line flash recognition algorithm, looking for optical transients, can use parallax information toassure that events observed from both sites have parallax angle smaller than the error of astrometry. On the other hand, the remaining OT candidates can be verified against a hypothesis of being near-Earth objects. This paper presents algorithm using parallax information for identification of near-Earth objects, which might be satellites, or space debris elements. Preliminary results of the algorithm are also presented

    Computational investigation of diesel nozzle internal flow during the complete injection event

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    [EN] Currently, diesel engines are calibrated using more and more complex multiple injection strategies. Under these conditions, the characteristics of the flow exiting the fuel injector are strongly affected by the transient interaction between the needle, the sac volume and the orifices, which are not yet clear. In the current paper, a methodology combining a 1D injector model and 3D-CFD simulations is proposed. First, the characteristics of the nozzle flow have been experimentally assessed in transient conditions by means of injection rate and momentum flux measurements. Later, the 3D-CFD modeling approach has been validated at steady-state fixed lift conditions. Finally, a previously developed 1D injector model has been used to extract the needle lift profiles and transient pressure boundary conditions used for the full-transient 3D-CFD simulations, using adaptive mesh refinement (AMR) strategies to be able to simulate the complete injection rate starting from 1 mu m lift.This work was partly sponsored by "Ministerio de Economia y Competitividad'', of the Spanish Government, in the frame of the Project "Estudio de la interaccion chorro-pared en condiciones realistas de motor'', Reference TRA2015-67679-c2-1-R. The authors would like also to thank the computer resources, technical expertise and assistance provided by Universidad de Valencia in the use of the supercomputer "Tirant''. Mr. Jaramillo's Thesis is funded by "Conselleria d'Educacio, Cultura i Esports'' of Generalitat Valenciana in the frame of the program "Programa VALI + D para investigadores en formacion, Reference ACIF/2015/040.Salvador, FJ.; De La Morena, J.; Bracho Leon, G.; Jaramillo-Císcar, D. (2018). Computational investigation of diesel nozzle internal flow during the complete injection event. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 40(3):153-167. https://doi.org/10.1007/s40430-018-1074-zS153167403Hall CAS, Lambert JG, Balogh SB (2014) EROI of different fuels and the implications for society. Energy Policy 64:141–152. https://doi.org/10.1016/j.enpol.2013.05.049Lujan JM, Tormos B, Salvador FJ, Gargar K (2009) Comparative analysis of a DI diesel engine fuelled with biodiesel blends during the European MVEG-A cycle: preliminary study (I). 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    3D echocardiographic reference ranges for normal left ventricular volumes and strain: Results fromthe EACVI NORRE study

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    Aim To obtain the normal ranges for 3D echocardiography (3DE) measurement of left ventricular (LV) volumes, function, and strain from a large group of healthy volunteers. Methods and results A total of 440 (mean age: 45613 years) out of the 734 healthy subjects enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study had good-quality 3DE data sets that have been analysed with a vendor-independent software package allowing homogeneous measurements regardless of the echocardiographic machine used to acquire the data sets. Upper limits of LV end-diastolic and end-systolic volumes were larger in men (97 and 42 mL/m2) than in women (82 and 35 mL/m2; P<0.0001). Conversely, lower limits of LV ejection fraction were higher in women than in men (51% vs. 50%; P<0.01). Similarly, all strain components were higher in women than in men. Lower range was -18.6% in men and -19.5% in women for 3D longitudinal strain, -27.0% and -27.6% for 3D circumferential strain, -33.2% and -34.4% for 3D tangential strain and 38.8% and 40.7% for 3D radial strain, respectively. LV volumes decreased with age in both genders (P<0.0001), whereas LV ejection fraction increased with age only in men. Among 3DE LV strain components, the only one, which did not change with age was longitudinal strain. Conclusion The NORRE study provides applicable 3D echocardiographic reference ranges for LV function assessment. Our data highlight the importance of age- and gender-specific reference values for both LV volumes and strain. All rights reserved

    Natural Killer Cells from Patients with Recombinase-Activating Gene and Non-Homologous End Joining Gene Defects Comprise a Higher Frequency of CD56bright NKG2A+++ Cells, and Yet Display Increased Degranulation and Higher Perforin Content.

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    Mutations of the recombinase Activating Genes 1 and 2 (RAG1, RAG2) in humans are associated with a broad range of phenotypes. For patients with severe clinical presentation, hematopoietic stem cell transplantation (HSCT) represents the only curative treatment, however high rates of graft failure and incomplete immune reconstitution have been observed, especially after unconditioned haploidentical transplantation. Studies in mice have shown that Rag-/- NK cells have a mature phenotype, reduced fitness and increased cytotoxicity. We aimed to analyze NK cell phenotype and function in patients with mutations in RAG and in non-homologous end joining (NHEJ) genes. Here we provide evidence that NK cells from these patients have an immature phenotype, with significant expansion of CD56bright CD16-/int CD57- cells, yet increased degranulation and high perforin content. Correlation was observed between in vitro recombinase activity of the mutant proteins, NK cell abnormalities, and in vivo clinical phenotype. Addition of serotherapy in the conditioning regimen, with the aim of depleting the autologous NK cell compartment, may be important to facilitate engraftment and immune reconstitution in patients with RAG and NHEJ defects treated by HSCT

    Changes associated with Ebola virus adaptation to novel species.

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    Motivation: Ebola viruses are not pathogenic but can be adapted to replicate and cause disease in rodents. Here, we used a structural bioinformatics approach to analyze the mutations associated with Ebola virus adaptation to rodents to elucidate the determinants of host-specific Ebola virus pathogenicity. Results: We identified 33 different mutations associated with Ebola virus adaptation to rodents in the proteins GP, NP, L, VP24, and VP35. Only VP24, GP and NP were consistently found mutated in rodent-adapted Ebola virus strains. Fewer than five mutations in these genes seem to be required for the adaptation of Ebola viruses to a new species. The role of mutations in GP and NP is not clear. However, three VP24 mutations located in the protein interface with karyopherin 5 may enable VP24 to inhibit karyopherins and subsequently the host interferon response. Three further VP24 mutations change hydrogen bonding or cause conformational changes. Hence, there is evidence that few mutations including crucial mutations in VP24 enable Ebola virus adaptation to new hosts. Since Reston virus, the only non-human pathogenic Ebolavirus species circulates in pigs in Asia, this raises concerns that few mutations may result in novel human pathogenic Ebolaviruses
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