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181.
Natural vs. mariculture induced variability in nutrients and plankton in the eastern Mediterranean 总被引:1,自引:0,他引:1
Paraskevi Pitta Ioannis Karakassis Manolis Tsapakis Snezana Zivanovic 《Hydrobiologia》1998,391(1-3):179-192
The water column in three Mediterranean fish farms was investigated in terms of physical, chemical and biological characteristics. A significant increase in concentrations of phosphate and ammonium was detected within the cages over the control site in one of the farms but without any significant effect on chlorophyll concentration. Analysis of variation within the data set identified location and season as the major factors of variability in most of the variables examined except phosphate and ammonium for which variability induced by fish farming seemed to be of major importance. Plankton abundance for the major taxonomic groups (diatoms, flagellates, dinoflagellates and ciliates), microplankton species diversity and community structure were also determined by the effects of season and location rather than by fish farming. 相似文献
182.
183.
Paraskevi Kapetanopoulou George Tagaras 《Flexible Services and Manufacturing Journal》2009,21(3-4):92-113
This paper presents an empirical study of certain features of the practices and management of value recovery processes that follow the acquisition of used products. The research focuses on the implementation of refurbishing and remanufacturing in small and medium enterprises. Twelve cases have been examined in detail, representing both original equipment manufacturers (OEMs) and independent remanufacturers (IRs), with different products and nature of operations. The analysis indicates that the factors having the strongest influence on the choice of value-added product recovery activities (PRA) at the OEMs are the type, features, and quality of the returned products, along with the consumer perceptions for recovered products, while the main factor influencing the choice of PRA for IRs is market demand for recovered products. Furthermore, willingness to pay for a recovered product constitutes the basic factor defining the pricing policy for recovered products. The findings of the research also include measurements of important quantifiable parameters of refurbishing and remanufacturing, such as the actual costs and prices expressed as fractions of the respective values for new products. 相似文献
184.
Information on the metal biological fate in macrophyte-based coastal lagoons is provided; this information can contribute
to the assessment of the environmental effects of metal pollution and to the development of predictive models for rational
management of coastal lagoons. Iron, Zn, Cu, Pb and Cd concentrations in the dominant invertebrate and fish species of Monolimni
Lagoon, Mediterranean Sea, as well as in potential major sources for metal accumulation in these animals (water, sediments,
angiosperms, seaweeds), were measured. Principal Component Analysis (PCA) was conducted using metal concentrations in invertebrates
and fishes. All five metal concentrations loaded significantly on the first PCA axis; however, Zn and Cu loadings were less
significant than Cd and even less than Fe and Pb ones. The samples of deposit-feeding invertebrates were separated from those
of the rest of the organisms (browsing, herbivorous and carnivorous invertebrates, carnivorous gobies and muscle tissues of
detritivorous mullets) along the first PCA axis. Deposit-feeding invertebrates displayed the highest Fe and Pb contents, and
in general, the highest or comparatively high Cd, Zn and Cu ones. Carnivorous gobies showed comparatively high Zn contents
and carnivorous shrimps the highest Cu ones, while muscle tissues of detritivorous mullets had low metal loads. In addition,
there was no essential increase in metal concentrations corresponding to the increasing trophic level (autotrophs, to herbivores,
to carnivores). Our findings suggest that (a) the variability in Fe, Pb and Cd contents in invertebrates and gobies depends
at least to some extent on interspecific differences in feeding habits—deposit feeders accumulated the highest metal amounts
probably due to high rates of uptake from sediments, (b) the variability in Zn and Cu concentrations in these organisms depends
also on other interspecific differences apart from those in feeding habits, (c) metal accumulation in mullet muscle tissues
does not depend markedly on feeding habits and (d) the trophic transfer of macrophyte-bound metals to the coastal lagoon food
web is of relatively minor importance. 相似文献
185.
Konstantina Katsarou Eirini Bardani Paraskevi Kallemi Kriton Kalantidis 《BioEssays : news and reviews in molecular, cellular and developmental biology》2019,41(10)
Viruses are essentially composed of a nucleic acid (segmented or not, DNA, or RNA) and a protein coat. Despite their simplicity, these small pathogens are responsible for significant economic and humanitarian losses that have had dramatic consequences in the course of human history. Since their discovery, scientists have developed different strategies to efficiently detect viruses, using all possible viral features. Viruses shape, proteins, and nucleic acid are used in viral detection. In this review, the development of these techniques, especially for plant and mammalian viruses, their strengths and weaknesses as well as the latest cutting‐edge technologies that may be playing important roles in the years to come are described. 相似文献