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Comparative Way (comparative + way)
Selected AbstractsDispersal and life span spectra in plant communities: a key to safe site dynamics, species coexistence and conservationECOGRAPHY, Issue 2 2002Roel J. Strykstra Dispersal and life span of individual plant species within five plant communities were assessed to obtain a characterization of these communities in this respect. Such a characterization is important in the context of restoration and maintenance. The most frequent species of five communities were ranked in eight classes according to their level of seed dispersal capability, their seed bank formation (dispersal in time and space) and their individual life span. In the communities, all eight classes were found, but communities differed in the distribution of the species over the classes. A theoretical framework was constructed to use the level of specialization of plant species in terms of dispersal in space and time, and life span, to define the characteristics of safe site dynamics within communities. Following simple rules, the relative reliability of the occurrence of safe sites in space and time was defined. After that, the relative reliability of the habitat was linked to the best fitting combination of trait specialization level. Having defined this link, communities could be characterized in a comparative way by their level and pattern of reliability of the opportunities for recruitment in space and time. The meaning of the coexistence of a range of trait combinations in one community was discussed. It was postulated that habitat reliability can explain this by assuming that the habitat of the community is part of a larger system, or consists of several "subsystems". These insights need to be considered in nature conservation. Succession and also specializations beyond the scope of dispersal and life span may influence the occurrence of species in a seemingly unfit habitat (for instance the occurrence of semi parasitic annuals in a community of perennials, because they use the perennial root system of other species). Finally, the meaning of safe site reliability in space and time in the context of restoration of communities was discussed. The reliability in space and time may be different today from that of the past, which restricts the feasibility of restoration of communities. [source] Combined measurements of egg fatty acids and stable isotopes as indicators of feeding ecology in lake-dwelling birdsFRESHWATER BIOLOGY, Issue 9 2009FRANCISCO RAMÍREZ Summary 1.,We examined whether egg fatty acid (FA) profiles and stable isotopes (SIA) could be used in a comparative way to infer the diet of two aquatic bird species with contrasting feeding habits: a surface forager, the pheasant-tailed jacana (Hydrophasianus chirurgus), and a pursuit-diving forager, the little cormorant (Phalacrocorax niger), at Haleji Lake (Pakistan). 2.,The species differed markedly in the overall percentage of saturated and polyunsaturated fatty acids. Moreover, among jacanas, two groups of birds had relatively high or low concentrations of long-chain essential PUFAs (such as 18:2 n-6 and 20:4 n-6), suggesting differing contributions from animal prey and plant material. 3.,These trophic differences were corroborated by ,15N values which indicated both a higher trophic position in cormorants relative to jacanas, and differences in trophic position for the two groups of jacanas. In this latter species ,13C values in both groups also pointed to differing diets, involving mainly grazing plants or a contribution from animal resources (aquatic invertebrates or insects). 4.,Both lower values of ,13C and higher percentages of 18:1 n-7 detected in little cormorants may indicate the influence of the anoxic water, typical of a freshwater system densely covered by macrophytes. 5.,These results indicate how both biomarkers offer complementary information in studies of feeding ecology, refining interpretations of trophic pathways which are usually based on FA or SIA alone. Comparisons of FA profiles and SIA among species also proved to be a reliable approach for inferring the diet of species for which information is scarce or contradictory, as is the case for the pheasant-tailed jacana. [source] Inhibitory effects of Cu, Zn, Ni and Co on nitrification and relevance of speciationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2010Ferhan Çeçen Abstract BACKGROUND: The speciation of metals is often overlooked in understanding their observed inhibitory effect in biological systems, in particular in nitrification systems. This study examines the effects of Cu, Zn, Ni and Co on a nitrifying sludge, where the aim is to relate inhibition to speciation. RESULTS: Nitrification inhibition was monitored by O2 and CO2 measurements, an approach rarely followed to date. The IC50 value of each metal was expressed in terms of total, free and labile metal. Zn and Cu formed similar species, but had different free and labile fractions. Although free and labile fractions of Cu were much lower than the others, it was the most inhibitory metal. Ni and Co exhibited quite different inhibitory effects on nitrification despite the formation of similar metal species. Co was the least inhibitory metal and exhibited its effect very slowly. CONCLUSION: The study is among the few which examine inhibition and speciation of several metals in a comparative way. In the same nitrification medium each metal formed different species, which is a factor to be considered in interpretation of inhibition. The results may be projected to nitrifying systems to clarify the underlying factors in inhibition. Copyright © 2009 Society of Chemical Industry [source] Free-Standing HVPE-GaN Quasi-Substrates: Impurity and Strain DistributionsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003T. Paskova Abstract We report a study of the physical properties of free-standing HVPE-GaN quasi-substrates. A variety of characterization techniques was employed in order to characterise in a comparative way the two sides of the films. The as-grown Ga-face was found to have lower density of both, structural and impurity defects. This leads to a lower concentration of free carriers and residual strain in the Ga-face compared to that in the N-face. The optical properties were found to be strongly influenced by the specific defect structure in both faces. [source] PUTTING THE CIVIL SOCIETY SECTOR ON THE ECONOMIC MAP OF THE WORLDANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 2 2010Lester M. Salamon ABSTRACT,:,The past twenty-five years have witnessed a spectacular expansion of philanthropy, volunteering, and civil society organizations throughout the world. Indeed, we seem to be in the midst of a ,global associational revolution,' a worldwide upsurge of organized private voluntary activity. Despite the promise that this development holds, however, the nonprofit or civil society sector remains the invisible subcontinent on the social landscape of most countries, poorly understood by policymakers and the public at large, often encumbered by legal limitations, and inadequately utilized as a mechanism for addressing public problems. One reason for this is the lack of basic information on its scope, structure, financing, and contributions in most parts of the world. This lack of information is due in part to the fact that significant components of the nonprofit sector fall within the non-observed, or informal, economy, and in part to the way even the observed parts of this sector have historically been treated in the prevailing System of National Accounts (SNA). This paper provides an overview of a series of steps that have been taken over the past 20 years by researchers at the Johns Hopkins University in cooperation with colleagues around the world and, more recently, with officials in the United Nations Statistics Division and the International Labour Organization to remedy this situation, culminating in the issuance and initial implementation of a new United Nations Handbook on Nonprofit Institutions in the System of National Accounts and the forthcoming publication of a new International Labour Organization Manual on the Measurement of Volunteer Work. Taken together, these efforts point the way toward putting the civil society sector on the economic map of the world for the first time in a systematically comparative way. [source] | ||||||||||