999 resultados para 825-11


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Ecosystem services provided by the marine environment are fundamental to human health and well-being. Despite this, many marine systems are being degraded to an extent that may reduce their capacity to provide these ecosystem services. The ecosystem approach is a strategy for the integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way (UN Convention on Biological Diversity, 2000). Its application to marine management and spatial planning has been proposed as a means of maintaining the economic and social value of the oceans, not only in the present but for generations to come. Characterising the susceptibility of services (and combinations of services) to particular human activities based on knowledge of impacts on biodiversity and ecosystem functioning (as described in preceding chapters) is a challenge for future management of the oceans. In this chapter, we highlight the existing, but limited knowledge of how ecosystem services may be impacted by different human activities. We discuss how impacts on one service can impact multiple services and explore how the impacts on services can vary both spatially and temporally and according to context. We focus particularly on the effects on ecosystem services of activities whose impacts on biodiversity and ecosystem functioning have already been considered in previous chapters. Some of these activities are associated with poor management of ecosystem benefits, for example, from provisioning services (aquaculture and fisheries), or with excessive input of wastes, fertilisers and contaminants into the system overburdening the waste treatment and assimilation services. Other impacts are associated with the construction of structures or use of space designed to generate benefits from environmental services such as the presence of water as a carrier for shipping, or sources of wind, wave and tidal power. We discuss the trade-offs that are made, consciously or otherwise, between different ecosystem services, which arise from human activities to optimise or manage specific ecosystem services.

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El nombre Carici sylvaticae-Fagetum (sylvaticae) (Rivas-Martínez 1965) C. Navarro 1982 [Contribución al estudio de la flora y la vegetación del Duranguesado y la Busturia (Vizcaya): 81-82. Ed. Univ. Complutense, Madrid] fue propuesto para designar los hayedos basófilos de territorios orocantábricos y cántabro-euskaldunes, en sustitución del ilegítimo (Art. 34) Melico (uniflorae)-Fagetum cantabricum Rivas-Martínez 1965 [Anales Inst. Bot. Cavanilles 22: 383].

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Chapters 3 and 15 of Joyce's Ulysses exhibit glimpses of three dreams, fantasies and eventual nightmares linked to the figure of 'Haroun al Raschid.' Historically speaking, the latter was a powerful Caliph of Baghdad, a medieval potentate about whom many of the most memorable of The Thousand and One Nights or The Arabian Nights' Entertainments were once and then again spun as tales of pleasure. Joyce seizes upon the figure of 'Haroun al Raschid' as a fictive measure to articulate the 'orientalist' fantasies of Stephen Dedalus and Leopold Bloom. However, this evocative figure of Near Eastern history, of fabulous narrative and the progressively converging fantasies of two modern European literary characters is riddled with paradox. Such material provides Joyce a perceptive and proleptic sense of the paradoxes and brutal historical contradictions through which Western and Eastern dreams of theocratic nationalism, ethnic zealotry, colonial rebellion and Zionism are to be played out. W. B. Yeats' poem 'The Gift of Harun al-Raschid', written in 1923, the year after the book publication of Ulysses, provides both a fitting foil and a significant socio-historical point of reference for Joyce's own figurative use of the Caliph of Baghdad.

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Math-Towers (www.math-towers.ca) is an online resource for students in grades 6 to 10 that supports collaborative problem-solving and investigations. This paper presents the philosophical position motivating the development of Math-Towers and describes how the site presents and motivates the mathematical challenges and supports participants' exploration and collaboration.

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This article draws on the author's experience of living and working in Belfast, Northern Ireland. Connections between the traumatic events of September 11 and the situation in the north of Ireland of ongoing civil conflict and violence are developed and aspects of therapeutic practice are described. Coping with the effects of trauma presents systemic therapists with multiple and complex challenges in whatever sociopolitical context they practice. A therapist stance that combines flexibility and openness of attitude with the creative use of therapeutic practices, including those from other modalities, will assist systemic therapists in rising to these challenges.

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Raman microscopy, based upon the inelastic scattering (Raman) of light by molecular species, has been applied as a specific structural probe in a wide range of biomedical samples. The purpose of the present investigation was to assess the potential of the technique for spectral characterization of the porcine outer retina derived from the area centralis, which contains the highest proportion of cone:rod cell ratio in the pig retina. METHODS: Retinal cross-sections, immersion-fixed in 4% (w/v) PFA and cryoprotected, were placed on salinized slides and air-dried prior to direct Raman microscopic analysis at three excitation wavelengths, 785 nm, 633 nm, and 514 nm. RESULTS: Raman spectra of each of the photoreceptor inner and outer segments (PIS, POS) and of the outer nuclear layer (ONL) of the retina acquired at 785 nm were dominated by vibrational features characteristic of proteins and lipids. There was a clear difference between the inner and outer domains in the spectroscopic regions, amide I and III, known to be sensitive to protein conformation. The spectra recorded with 633 nm excitation mirrored those observed at 785 nm excitation for the amide I region, but with an additional pattern of bands in the spectra of the PIS region, attributed to cytochrome c. The same features were even more enhanced in spectra recorded with 514 nm excitation. A significant nucleotide contribution was observed in the spectra recorded for the ONL at all three excitation wavelengths. A Raman map was constructed of the major spectral components found in the retinal outer segments, as predicted by principal component analysis of the data acquired using 633 nm excitation. Comparison of the Raman map with its histological counterpart revealed a strong correlation between the two images. CONCLUSIONS: It has been demonstrated that Raman spectroscopy offers a unique insight into the biochemical composition of the light-sensing cells of the retina following the application of standard histological protocols. The present study points to the considerable promise of Raman microscopy as a component-specific probe of retinal tissue.

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Wireless enabled portable devices must operate with the highest possible energy efficiency while still maintaining a minimum level and quality of service to meet the user's expectations. The authors analyse the performance of a new pointer-based medium access control protocol that was designed to significantly improve the energy efficiency of user terminals in wireless local area networks. The new protocol, pointer controlled slot allocation and resynchronisation protocol (PCSAR), is based on the existing IEEE 802.11 point coordination function (PCF) standard. PCSAR reduces energy consumption by removing the need for power saving stations to remain awake and listen to the channel. Using OPNET, simulations were performed under symmetric channel loading conditions to compare the performance of PCSAR with the infrastructure power saving mode of IEEE 802.11, PCF-PS. The simulation results demonstrate a significant improvement in energy efficiency without significant reduction in performance when using PCSAR. For a wireless network consisting of an access point and 8 stations in power saving mode, the energy saving was up to 31% while using PCSAR instead of PCF-PS, depending upon frame error rate and load. The results also show that PCSAR offers significantly reduced uplink access delay over PCF-PS while modestly improving uplink throughput.

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Results of the search of the periodic changes of the 530.3 nm line intensity emitted by selected structures of the solar corona in the frequency range 1-10 Hz are presented. A set of 12 728 images of the section of the solar corona extending from near the north pole to the south-west were taken simultaneously in the 530.3 nm ("green") line and white-light with the Solar Eclipse Coronal Imaging System (SECIS) during the 143-seconds- long totality of the 1999 August 11 solar eclipse observed in Shabla, Bulgaria. The time resolution of the collected data is better than 0.05 s and the pixel size is approximately 4 arcsec. Using classical Fourier spectral analysis tools, we investigated temporal changes of the local 530.3 nm coronal line brightness in the frequency range 1-10 Hz of thousands of points within the field of view. The various photometric and instrumental effects have been extensively considered. We did not find any indisputable, statistically significant evidence of periodicities in any of the investigated points (at significance level alpha = 0.05).