61 research outputs found

    Introducing Variable Factors For Optical Backbone Interconnection Planning

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    Using Location-Allocation Algorithms to Distribute Multioutlet Hydrants in Irrigation Networks Design

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    Location-allocation algorithms allow for situating services in an efficient way in zones where the demand is dispersed across the area. In the present work, the minisum location-allocation algorithm is used to optimize the placement multioutlet hydrants, which are needed to supply irrigation to the region. The objective function aims to minimize the total access costs of the service. Because the total number of hydrants is the same as what currently exists the results can be compared with the presented solution. The proposed model reduces the total distance run to access the service, from 16,177 m to 13,560 m (16.17%), and the objective function (proportional to the cost) by 28.95%. © 2012 American Society of Civil Engineers.González Villa, FJ.; García Prats, A. (2011). Using Location-Allocation Algorithms to Distribute Multioutlet Hydrants in Irrigation Networks Design. Journal of Irrigation and Drainage Engineering. 274-283. doi:10.1061/(ASCE)IR.1943-4774.0000405S27428

    Polytetrahedral Clusters

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    By studying the structures of clusters bound by a model potential that favours polytetrahedral order, we find a previously unknown series of `magic numbers' (i.e. sizes of special stability) whose polytetrahedral structures are characterized by disclination networks that are analogous to hydrocarbons.Comment: 4 pages, 4 figure

    Noncrystalline structures of ultrathin unsupported nanowires

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    Computer simulations suggest that ultrathin metal wires should develop exotic, non-crystalline stable atomic structures, once their diameter decreases below a critical size of the order of a few atomic spacings. The new structures, whose details depend upon the material and the wire thickness, may be dominated by icosahedral packings. Helical, spiral-structured wires with multi-atom pitches are also predicted. The phenomenon, analogous to the appearance of icosahedral and other non-crystalline shapes in small clusters, can be rationalized in terms of surface energy anisotropy and optimal packing

    Ectopic Cushing' syndrome caused by a neuroendocrine carcinoma of the mesentery

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    BACKGROUND: ACTH overproduction within the pituitary gland or ectopically leads to hypercortisolism. Here, we report the first case of Cushing' syndrome caused by an ectopic ACTH-secreting neuroendocrine carcinoma of the mesentery. Moreover, diagnostic procedures and pitfalls associated with ectopic ACTH-secreting tumors are demonstrated and discussed. CASE PRESENTATION: A 41 year-old man presented with clinical features and biochemical tests suggestive of ectopic Cushing's syndrome. First, subtotal thyroidectomy was performed without remission of hypercortisolism, because an octreotide scan showed increased activity in the left thyroid gland and an ultrasound revealed nodules in both thyroid lobes one of which was autonomous. In addition, the patient had a 3 mm hypoenhancing lesion of the neurohypophysis and a 1 cm large adrenal tumor. Surgical removal of the pituitary lesion within the posterior lobe did not improve hypercortisolism and we continued to treat the patient with metyrapone to block cortisol production. At 18-months follow-up from initial presentation, we detected an ACTH-producing neuroendocrine carcinoma of the mesentery by using a combination of octreotide scan, computed tomography scan, and positron emission tomography. Intraoperatively, use of a gamma probe after administration of radiolabeled (111)In-pentetreotide helped identify the mesenteric neuroendocrine tumor. After removal of this carcinoma, the patient improved clinically. Laboratory testing confirmed remission of hypercortisolism. An octreotide scan 7 months after surgery showed normal results. CONCLUSION: This case underscores the diagnostic challenge in identifying an ectopic ACTH-producing tumor and the pluripotency of cells, in this case of mesenteric cells that can start producing and secreting ACTH. It thereby helps elucidate the pathogenesis of neuroendocrine tumors. This case also suggests that patients with ectopic Cushing's syndrome and an octreotide scan positive in atypical locations may benefit from explorative radioguided surgery using (111)In-pentetreotide and a gamma probe

    Challenges for adaptive dialogue management in the KRISTINA project

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    Access to health care related information can be vital and should be easily accessible. However, immigrants often have difficulties to obtain the relevant information due to language barriers and cultural differences. In the KRISTINA project, we address those difficulties by creating a socially competent multimodal dialogue system that can assist immigrants in getting information about health care related questions. Dialogue management, as core component responsible for the system behaviour, has a significant impact on the successful reception of such a system. Hence, this work presents the specific challenges of the KRISTINA project to adaptive dialogue management, namely the handling of a large dialogue domain and the cultural adaptability required by the envisioned dialogue system, and our approach to handling them

    Networks of Minimum Length

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