137 research outputs found

    Using NLP technology in CALL

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    This paper outlines the research and guiding research principles of the (I)CALL group at Dublin City University, Ireland. Our research activities include the development of (I)CALL systems targeted at a variety of user groups including advanced Romance language learners, intermediate to advanced German learners, primary and secondary school students as well as students with L1 learning disabilities requiring a variety of system types which cater to individual user needs and abilities. Suitable CL/NLP technology is incorporated where appropriate for the learner

    Potential Vorticity Evolution of a Protoplanetary Disk with An Embedded Protoplanet

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    We present two-dimensional inviscid hydrodynamic simulations of a protoplanetary disk with an embedded planet, emphasizing the evolution of potential vorticity (the ratio of vorticity to density) and its dependence on numerical resolutions. By analyzing the structure of spiral shocks made by the planet, we show that progressive changes of the potential vorticity caused by spiral shocks ultimately lead to the excitation of a secondary instability. We also demonstrate that very high numerical resolution is required to both follow the potential vorticity changes and identify the location where the secondary instability is first excited. Low-resolution results are shown to give the wrong location. We establish the robustness of a secondary instability and its impact on the torque onto the planet. After the saturation of the instability, the disk shows large-scale non-axisymmetry, causing the torque on the planet to oscillate with large amplitude. The impact of the oscillating torque on the protoplanet's migration remains to be investigated.Comment: 17 pages total with 9 figures (Fig.4,5,9 are in .jpg), accepted to Ap

    Application and testing of the L neural network with the self-consistent magnetic field model of RAM-SCB

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    Abstract We expanded our previous work on L neural networks that used empirical magnetic field models as the underlying models by applying and extending our technique to drift shells calculated from a physics-based magnetic field model. While empirical magnetic field models represent an average, statistical magnetospheric state, the RAM-SCB model, a first-principles magnetically self-consistent code, computes magnetic fields based on fundamental equations of plasma physics. Unlike the previous L neural networks that include McIlwain L and mirror point magnetic field as part of the inputs, the new L neural network only requires solar wind conditions and the Dst index, allowing for an easier preparation of input parameters. This new neural network is compared against those previously trained networks and validated by the tracing method in the International Radiation Belt Environment Modeling (IRBEM) library. The accuracy of all L neural networks with different underlying magnetic field models is evaluated by applying the electron phase space density (PSD)-matching technique derived from the Liouville\u27s theorem to the Van Allen Probes observations. Results indicate that the uncertainty in the predicted L is statistically (75%) below 0.7 with a median value mostly below 0.2 and the median absolute deviation around 0.15, regardless of the underlying magnetic field model. We found that such an uncertainty in the calculated L value can shift the peak location of electron phase space density (PSD) profile by 0.2 RE radially but with its shape nearly preserved. Key Points L* neural network based on RAM-SCB model is developed L* calculation accuracy is estimated by PSD matching using RBSP data L* uncertainty causes a radial shift in the electron phase space density profile

    The Anomalous Infrared Emission of Abell 58

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    We present a new model to explain the excess in mid and near infrared emission of the central, hydrogen poor dust knot in the planetary nebula (PN) Abell 58. Current models disagree with ISO measurement because they apply an average grain size and equilibrium conditions only. We investigate grain size distributions and temperature fluctuations affecting infrared emission using a new radiative transfer code and discuss in detail the conditions requiring an extension of the classical description. The peculiar infrared emission of V605 Aql, the central dust knot in Abell 58, has been modeled with our code. V605 Aql is of special interest as it is one of only three stars ever observed to move from the evolutionary track of a central PN star back to the post-AGB state.Comment: 17 pages, 4 figures; accepted and to be published in Ap

    Mitochondrial Haplogroups, Control Region Polymorphisms and Malignant Melanoma: A Study in Middle European Caucasians

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    Because mitochondria play an essential role in energy metabolism, generation of reactive oxygen species (ROS), and apoptosis, sequence variation in the mitochondrial genome has been postulated to be a contributing factor to the etiology of multifactorial age-related diseases, including cancer. The aim of the present study was to compare the frequencies of mitochondrial DNA (mtDNA) haplogroups as well as control region (CR) polymorphisms of patients with malignant melanoma (n = 351) versus those of healthy controls (n = 1598) in Middle Europe.Using primer extension analysis and DNA sequencing, we identified all nine major European mitochondrial haplogroups and known CR polymorphisms. The frequencies of the major mitochondrial haplogroups did not differ significantly between patients and control subjects, whereas the frequencies of the one another linked CR polymorphisms A16183C, T16189C, C16192T, C16270T and T195C were significantly higher in patients with melanoma compared to the controls. Regarding clinical characteristics of the patient cohort, none of the nine major European haplogroups was associated with either Breslow thickness or distant metastasis. The CR polymorphisms A302CC-insertion and T310C-insertion were significantly associated with mean Breslow thickness, whereas the CR polymorphism T16519C was associated with metastasis.Our results suggest that mtDNA variations could be involved in melanoma etiology and pathogenesis, although the functional consequence of CR polymorphisms remains to be elucidated

    Closure of a Large Chronic Wound through Transplantation of Gene-Corrected Epidermal Stem Cells

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    Generalized junctional epidermolysis bullosa (JEB) is caused by mutations in LAMA3,LAMB3,or LAMC2,which together encode laminin-332, a hetero-trimeric protein consisting ofa3,b3, andg2chain. In nonlethal generalized intermediate JEB, laminin-332 is highly reduced, and hemidesmosomes are rudimentary or completely absent, leading to blister formation within the lamina lucida of the basement membrane upon minor trauma. The resulting chronic skin wounds invariably develop recurrent infections and scarring, which greatly impair patients’ quality of life. We report on a patient in whom gene-corrected epidermal sheets were transplanted onto a large nonhealing epidermal ulceration following a good manufacturing practice protoco

    Grundlagen zur Bodenfruchtbarkeit - Die Beziehung zum Boden gestalten

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    Die BroschĂŒre beleuchtet die Bodenfruchtbarkeit aus verschiedenen wissenschaftlichen und bĂ€uerlichen Blickwinkeln. Die Informationen wollen praktische Beobachtungen der Landwirte ergĂ€nzen und dazu anregen, die Beziehung zum Boden zu ĂŒberdenken und eine wirklich nachhaltige Bodenkultur zu praktizieren

    Humoral immunity in dually vaccinated SARS-CoV-2-naĂŻve individuals and in booster-vaccinated COVID-19 convalescent subjects

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    Background The immune response to COVID-19-vaccination differs between naĂŻve vaccinees and those who were previously infected with SARS-CoV-2. Longitudinal quantitative and qualitative serological differences in these two distinct immunological subgroups in response to vaccination are currently not well studied. Methods We investigate a cohort of SARS-CoV-2-naĂŻve and COVID-19-convalescent individuals immediately after vaccination and 6 months later. We use different enzyme-linked immunosorbent assay (ELISA) variants and a surrogate virus neutralization test (sVNT) to measure IgG serum titers, IgA serum reactivity, IgG serum avidity and neutralization capacity by ACE2 receptor competition. Results Anti-receptor-binding domain (RBD) antibody titers decline over time in dually vaccinated COVID-19 naĂŻves whereas titers in single dose vaccinated COVID-19 convalescents are higher and more durable. Similarly, antibody avidity is considerably higher among boosted COVID-19 convalescent subjects as compared to dually vaccinated COVID-19-naĂŻve subjects. Furthermore, sera from boosted convalescents inhibited the binding of spike-protein to ACE2 more efficiently than sera from dually vaccinated COVID-19-naĂŻve subjects. Conclusions Long-term humoral immunity differs substantially between dually vaccinated SARS-CoV-2-naĂŻve and COVID-19-convalescent individuals. Booster vaccination after COVID-19 induces a more durable humoral immune response in terms of magnitude and quality as compared to two-dose vaccination in a SARS-CoV-2-naĂŻve background
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