26,019 research outputs found

    Quality-of-service routing with two concave constraints

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    Routing is a process of finding a network path from a source node to a destination node. A good routing protocol should find the "best path" from a source to a destination. When there are independent constraints to be considered, the "best path" is not well-defined. In our previous work, we developed a line segment representation for Quality-of-Service routing with bandwidth and delay requirements. In this paper, we propose how to adopt the line segment when a request has two concave constraints. We have developed a series of operations for constructing routing tables under the distance-vector protocol. We evaluate the performance through extensive simulations. ©2008 IEEE.published_or_final_versio

    Discrete adjoint approximations with shocks

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    This paper is concerned with the formulation and discretisation of adjoint equations when there are shocks in the underlying solution to the original nonlinear hyperbolic p.d.e. For the model problem of a scalar unsteady one-dimensional p.d.e. with a convex flux function, it is shown that the analytic formulation of the adjoint equations requires the imposition of an interior boundary condition along any shock. A 'discrete adjoint' discretisation is defined by requiring the adjoint equations to give the same value for the linearised functional as a linearisation of the original nonlinear discretisation. It is demonstrated that convergence requires increasing numerical smoothing of any shocks. Without this, any consistent discretisation of the adjoint equations without the inclusion of the shock boundary condition may yield incorrect values for the adjoint solution

    Adjustable transmission power in wireless Ad Hoc networks with smart antennas

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    In this paper, we present a model to analyze the performance of wireless ad hoc networks with smart antennas, i.e. directional antennas with adjustable transmission power. Our results show that smart antennas can improve the network performance by mitigating the effects of interference. We illustrate our model with the NFP (Nearest with Forward Progress) transmission strategy. Our analytical and simulation results show that, for ad hoc networks with smart antennas, NFP yields good throughput and remains stable as the node density varies. © 2008 IEEE.published_or_final_versionThe Proceedings of the IEEE Global Telecommunications Conference (GLOBECOM 2008), New Orleans, LO., USA, 30 November-4 December 2008, p. 1326-133

    Figurative Language: How is it Used in Basal Readings?

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    How much attention do editors of basal readers give to figurative language? What is the most common figure of speech found in basal readers? What is the least common figure of speech bound in basal readers? These were the questions the authors sought to answer through their research

    Transmission radius control in wireless Ad Hoc networks with smart antennas

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    In this paper, we present a model to analyze the performance of three transmission strategies with smart antennas, i.e. directional antennas with adjustable transmission power. Generally, a larger transmission radius contributes a greater progress if a transmission is successful. However, it has a higher probability of collision with other concurrent transmissions. Smart antennas mitigate collisions with sectorized transmission ranges. They also extend the transmission radii. By modelling three transmission strategies, namely, Nearest with Forward Progress (NFP), Most Forward with Fixed Radius (MFR), and Most Forward with Variable Radius (MVR), our analysis illustrates that the use of smart antennas can greatly reduce the possibility of conflicts. The model considers the interference range and computes the interference probability for each transmission strategy. We have analyzed two Medium Access Control (MAC) protocols using our interference model, namely, the slotted ALOHA protocol and the slotted CSMA/CA-like protocol. The result shows that, for slotted ALOHA, NFP yields the best one-hop throughput, whereas MVR provides the best average forward progress. The overall performance is substantially improved with the slotted CSMA/CA-like protocol, and the network becomes more resilient. © 2010 IEEE.published_or_final_versio

    Sacrohysteropexy with synthetic mesh in Aba, South‑Eastern Nigeria: A report of three cases and review of the literature

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    The surgical treatment of uterovaginal prolapse in women who wish to preserve their uteri for fertility presents a challenge to a gynecologist. This is particularly more challenging in Nigeria and the rest of Africa where there is not only a strong cultural aversion to hysterectomy but women also prefer large family size and male babies. This underscores the need for fertility friendly, uterus‑preserving procedures. Three young women under the age of 40 presented with uterovaginal prolapse. They were of low parity and wanted to preserve their uteri for future reproductive function. They had open abdominal suspension of their uteri to the sacrum using a synthetic polypropylene mesh. A pus‑string suture was also used to obliterate their pouch of Douglas to prevent future enterocele. Pelvic anatomy was restored and normal vaginal axis was achieved. They had uneventful post‑operative period. In resource‑limited settings, open abdominal (rather than laparoscopic) sacrohysteropexy with synthetic mesh is an effective and safe alternative to Manchester operation and other vaginal procedures in women who desire to preserve the uterus for future reproductive function.Keywords: Hysteropexy, synthetic mesh, utero‑vaginal prolapseNigerian Journal of Clinical Practice • Oct-Dec 2013 • Vol 16 • Issue

    When is parenteral nutrition indicated in the hospitalized, acutely ill patient?

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    PURPOSE OF REVIEW The current review discusses current practices regarding appropriate indications for parenteral nutrition in acutely ill hospitalized patients. We address-specific indications for parenteral nutrition in the perioperative period, and in inflammatory bowel disease, oncology, hepatobiliary, critical care and end-stage renal disease patients. RECENT FINDINGS Acutely ill hospitalized patients can develop intestinal failure requiring parenteral nutrition. Recent studies have provided insight into the main indications. The most common indications for inpatient parenteral nutrition include postsurgical complications, including prolonged ileus, sepsis, fistula and leaks, and bowel obstruction, predominantly malignant. Severe or complicated inflammatory bowel disease and cancer treatment-related mucosal enteropathies (mucositis, enterocolitis, gut graft-versus-host disease) are the next commonest indications. Less frequent indications are primary motility disorders and inability to secure enteral access for enteral nutrition. Gastrointestinal failure of the intensive care patient is a separate entity resulting from multiple mechanisms, including an enteropathy and dysmotility. SUMMARY Despite the wider availability of nutrition support teams, use of parenteral nutrition is not without risk. The risks and benefits of parenteral nutrition in the acute setting need to be carefully considered even when it is indicated

    Performance Analysis of Quantization-Based Approximation Algorithms for Precomputing the Supported QoS

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    Approximation algorithm for QoS routing with multiple additive constraints

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    In this paper, we study the problem of computing the supported QoS from a source to a destination with multiple additive constraints. The problem has been shown to be NP-complete and many approximation algorithms have been developed. We propose a new approximation algorithm called multi-dimensional relaxation algorithm. We formally prove that our algorithm produces smaller approximation error than the existing algorithms. We further verify the performance by extensive simulations. ©2009 IEEE.published_or_final_versio
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