2,024 research outputs found

    Minimización global de un polinomio en la recta real

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    En este art´ıculo presentamos y probamos num´ericamente un nuevo algoritmo para la minimizaci´on global de un polinomio de grado par. El algoritmo est´a basado en la simple idea de trasladar verticalmente el grafo del polinomio hasta que el eje OX sea tangente al grafo del polinomio trasladado. En esta privilegiada posici´on, cualquier ra´ız real del polinomio trasladado es un m´ınimo global del polinomio original

    Response of potential cucurbit rootstocks against Meloidogyne spp

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    the Cucurbita hybrids, usually used as cucurbit rootstocks, are susceptible to Meloidogyne. Its cultivation increases the nematode population densities at similar levels than ungrafted cucumber or melon crops, and higher 'Ievels than watermelon.Postprint (published version

    Grafting melons onto potential cucumis spp. rootstocks

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    Cucumís melo is an economically importar]t crop. Its culture is hampered by differen t types of soil stresses. Grafting melons onto different resistant cucurbits belonging to the genera, Cucurbíta, Lagenaría, Luffa, etc. have been successfully used to avoid these problems. However, me Ion quality has been nega.tively modified as a consequence of grafting. In general, variation in fruit shape, seed cavity and sugar content have been observed. The use of rootstocks more genetically c\oser to the melon scions could be useful to obtain fru i ts with better quality from melon grafted plantsPostprint (published version

    An assessment for UAS depart and approach operations

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    Unmanned Aerial Systems (UAS) have great potential to be used in a wide variety of civil applications such as environmental applications, emergency situations, surveillance tasks and more. The development of Flight Control Systems (FCS) coupled with the availability of other Commercial Off-The Shelf (COTS) components is enabling the introduction of UAS into the civil market. The sophistication of existing FCS is also making these systems accessible to end users with little aeronautics expertise. However, much work remains to be done to deliver systems that can be properly integrated in standard aeronautical procedures used by manned aviation. In previous research advances have been proposed in the flight plan capabilities by offering semantically much richer constructs than those present in most current UAS autopilots. The introduced flight plan is organized as a set of stages, each one corresponding to a different flight phase. Each stage contains a structured collection of legs inspired by current practices in Area Navigation (RNAV). However, the most critical parts of any flight, the depart and approach operations in an integrated airspace remain mostly unexplored. This paper introduces an assessment of both operations for UAS operating in VFR and IFR modes. Problems and potential solutions are proposed, as well as an automating strategy that should greatly reduce pilot workload. Although th

    Investigation of acceptor levels and hole scattering mechanisms in p-gallium selenide by means of transport measurements under pressure

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    The effect of pressure on acceptor levels and hole scattering mechanisms in p-GaSe is investigated through Hall effect and resistivity measurements under quasi-hydrostatic conditions up to 4 GPa. The pressure dependence of the hole concentration is interpreted through a carrier statistics equation with a single (nitrogen) or double (tin) acceptor whose ionization energies decrease under pressure due to the dielectric constant increase. The pressure effect on the hole mobility is also accounted for by considering the pressure dependencies of both the phonon frequencies and the hole-phonon coupling constants involved in the scattering rates.Comment: 13 pages, Latex, 4 ps figures. to appear in High Pressure Research 69 (1997

    Depart and approach procedures for UAS in a VFR environment

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    This paper assesses the depart and approach operations of Unmanned Aircraft Systems (UAS) in one of the most challenging scenarios: when flying under Visual Flight Rules (VFR). Inspired by some existing procedures for (manned) general aviation, some automatic and predefined procedures for UAS are proposed. Hence, standardized paths to specific waypoints close to the airport are defined for depart operations, just before starting the navigation phase. Conversely, and for the approach maneuvers, it is foreseen a first integration into a holding pattern near the landing runway (ideally above it) followed by a standard VFR airfield traffic pattern. This paper discusses the advantages of these operations which aim at minimizing possible conflicts with other existing aircraft while reducing the Pilot-in-Command workload. Finally, some preliminary simulations are shown where these procedures have been successfully tested with simulated surrounding traffic

    Understanding patients' experiences of the wish to hasten death: an updated and expanded systematic review and meta-ethnography

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    OBJECTIVES: Patients with advanced disease sometimes express a wish to hasten death (WTHD). In 2012, we published a systematic review and meta-ethnography of qualitative studies examining the experience and meaning of this phenomenon. Since then, new studies eligible for inclusion have been reported, including in Europe, a region not previously featured, and specifically in countries with different legal frameworks for euthanasia and assisted suicide. The aim of the present study was to update our previous review by including new research and to conduct a new analysis of available data on this topic. SETTING: Eligible studies originated from Australia, Canada, China, Germany, The Netherlands, Switzerland, Thailand and USA. PARTICIPANTS: Studies of patients with life-threatening conditions that had expressed the WTHD. DESIGN: The search strategy combined subject terms with free-text searching of PubMed MEDLINE, Web of Science, CINAHL and PsycInfo. The qualitative synthesis followed the methodology described by Noblit and Hare, using the 'adding to and revising the original' model for updating a meta-ethnography, proposed by France et al. Quality assessment was done using the Critical Appraisal Skills Programme checklist. RESULTS: 14 studies involving 255 participants with life-threatening illnesses were identified. Five themes emerged from the analysis: suffering (overarching theme), reasons for and meanings and functions of the WTHD and the experience of a timeline towards dying and death. In the context of advanced disease, the WTHD emerges as a reaction to physical, psychological, social and existential suffering, all of which impacts on the patient's sense of self, of dignity and meaning in life. CONCLUSIONS: The WTHD can hold different meanings for each individual-serving functions other than to communicate a genuine wish to die. Understanding the reasons for, and meanings and functions of, the WTHD is crucial for drawing up and implementing care plans to meet the needs of individual patients
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