2,804 research outputs found

    Finite amplitude gravity waves in the Venus atmosphere generated by surface topography

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    A two-dimensional, fully nonlinear, nonhydrostatic, gravity wave model is used to study the evolution of gravity waves generated near the surface of Venus. The model extends from near the surface to well above the cloud layers. Waves are forced by applying a vertical wind at the bottom boundary. The boundary vertical wind is determined by the product of the horizontal wind and the gradient of the surface height. When wave amplitudes are small, the near-surface horizontal wind is the zonally averaged basic-state zonal wind, and the length scales of the forcing that results are characteristic of the surface height variation. When the forcing becomes larger and wave amplitudes affect the near-surface horizontal wind field, the forcing spectrum becomes more complicated, and a spectrum of waves is generated that is not a direct reflection of the spectrum of the surface height variation. Model spatial resolution required depends on the amplitude of forcing; for very nonlinear cases considered, vertical resolution was 250 m, and horizontal resolution was slightly greater than 1 km. For smaller forcing amplitudes, spatial resolution was much coarser, being 1 km in the vertical and about 10 km in the horizontal. Background static stability and mean wind are typical of those observed in the Venus atmosphere

    A Reality Checklist for Multi-Device Systems in the Wild?

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    This position paper proposes the development of a reality checklist for multi-device systems in the wild. The checklist will help researchers evaluate designs, design ideas or design specifications for a system before it is deployed in the wild

    Neonatal umbilical inflammatory myofibroblastic tumor

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    Inflammatory myofibroblastic tumors represent a tumor class of intermediate malignant potential predominantly seen in children and adolescents. Here is the first description of an inflammatory myofibroblastic tumor at the umbilicus of a neonate. In neonates the main sites of presentation are equally distributed between the thoracic and the abdominal region. In a third of the neonates the tumor is identified on an antenatal scan. The preferred treatment option is resection of the tumor. Spontaneous regression has been described.Keywords: inflammatory myofibroblastic tumor, neonatal tumor, surgical resection, umbilicu

    Supporting user adaptation in adaptive hypermedia applications

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    A hypermedia application offers its users a lot of freedom to navigate through a large hyperspace. The rich link structure of the hypermedia application can not only cause users to get lost in the hyperspace, but can also lead to comprehension problems because different users may be interested in different pieces of information or a different level of detail or difficulty. Adaptive hypermedia systems (or AHS for short) aim at overcoming these problems by providing adaptive navigation support and adaptive content. The adaptation is based on a user model that represents relevant aspects about the user. At the Eindhoven University of Technology we developed anAHS, named AHA {DC981. To describe its functionality and that of future adaptive systems we also developed a reference model for the architecture of adaptive hypermedia applications, named AHAM (for Adaptive Hypermedia Application Model) {DHW991. In AHAM knowledge is represented through hierarchies of large composite abstract concepts as well as small atomic ones. AHAM also divides the different aspects of an AHS into a domain model (DM). a user model (UM) and an adaptation model (AM). This division provides a clear separation of concerns when developing an adaptive hypermedia application. In this paper, we concentrate on the user modeling aspects of AHAM, but also describe how they relate to the domain model and the adaptation model. Also. we provide a separation between the adaptation rules an author or system designer writes (as part of the adaptation model) and the system's task of executing these rules in the right order. This distinction leads to a simplification of the author's or system designer's task to write adaptation rules. We illustrate authoring and adaptation in by some examples in the AHS AHA

    Supporting user adaptation in adaptive hypermedia applications

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    A hypermedia application offers its users a lot of freedom to navigate through a large hyperspace. The rich link structure of the hypermedia application can not only cause users to get lost in the hyperspace, but can also lead to comprehension problems because different users may be interested in different pieces of information or a different level of detail or difficulty. Adaptive hypermedia systems (or AHS for short) aim at overcoming these problems by providing adaptive navigation support and adaptive content. The adaptation is based on a user model that represents relevant aspects about the user. At the Eindhoven University of Technology we developed anAHS, named AHA {DC981. To describe its functionality and that of future adaptive systems we also developed a reference model for the architecture of adaptive hypermedia applications, named AHAM (for Adaptive Hypermedia Application Model) {DHW991. In AHAM knowledge is represented through hierarchies of large composite abstract concepts as well as small atomic ones. AHAM also divides the different aspects of an AHS into a domain model (DM). a user model (UM) and an adaptation model (AM). This division provides a clear separation of concerns when developing an adaptive hypermedia application. In this paper, we concentrate on the user modeling aspects of AHAM, but also describe how they relate to the domain model and the adaptation model. Also. we provide a separation between the adaptation rules an author or system designer writes (as part of the adaptation model) and the system's task of executing these rules in the right order. This distinction leads to a simplification of the author's or system designer's task to write adaptation rules. We illustrate authoring and adaptation in by some examples in the AHS AHA

    Joint ESM-EVBO meetings:past, present, and future

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    Accessory spleen as lead point in intussusception

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    A 15-year-old boy, who had an episode of abdominal colic 4 years earlier, presented now with a week-long episode of abdominal pain. A computed tomographic scan confirmed the presence of an intussusception. Surprisingly, the surgery identified an accessory spleen as the lead point. At 9 months follow-up, the young boy has had no further abdominal discomfort. This report adds accessory spleen to the list of very rare pathological lead points in intussusception
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