1,720,994 research outputs found
Short-term patch dynamics of macroinvertebrate colonization on decaying reed detritus in a Mediterranean lagoon (Lake Alimini Grande,Apulia, SE Italy)
Full text linkIn aquatic ecosystems, the ecology of macrophytal detritus aggregations has been investigated over a range of temporal scales. Yet, no attempts have been made to minimize the temporal resolution of the analysis, thus neglecting the occurrence of short-term colonization and decay dynamics for these ephemeral patches of high biological activity. The present study was carried out at two sampling sites in Lake Alimini Grande, a brackish lagoon in South-East Italy. The abundance of macroinvertebrate taxa colonizing prepared packs of reed leaf detritus and the ash-free dry mass of the packs were monitored daily for 40 days. Spectral analysis was used to investigate the fine-scale temporal dynamics of invertebrates colonization and leaf pack mass variations. The macrobenthos found on leaf packs was dominated at both sites by few taxa (i.e., the vagile Lekanesphaera monodi, Microdeutopus gryllotalpa, Neanthes caudata and the sessile Balanus sp.), whose general colonization patterns were described by unimodal curves. At a daily temporal resolution Balanus sp. was characterized by random short-term density variations, while vagile taxa showed non-random, highly site- and species-specific fluctuations generally characterized by an oscillation period comprised between 2 and 3 days. In addition, leaf packs were characterized by non-random, short-term mass oscillations, coherent and in phase with L. monodi abundance fluctuations. Our results highlight the occurrence of short-term, non-random density variations of invertebrate colonizers on leaf detritus patches. In addition, they emphasize a previously unexplored, fine-scale linkage between abundance patterns of invertebrate consumers and short-term mass variations of decaying detritus
Theory as an Option or Theory as a Must? The Bearing of Methodological Choices on the Role of Sociological Theory
No full textHighly valued, taught, and sought-after, the interplay of social theory and social research has virtually no critic, and this general agreement makes the oft-lamented lack of integration between the two somehow baffling. Robert Merton was one of the first and most prominent advocates of this marriage of empirical and epistemic relevance of sociological knowledge: this chapter starts by reviewing his original proposal, claiming that it has been more successful in convincing scholars of the inevitable empirical character of social theory than in showing how social research has a theoretical nature – to Merton, equally inevitable. Arguing that such interpenetration can be methodologically promoted or prevented, we thus analyze how non-theoretical (i.e., methodological and procedural) decisions affect the role of theorizing in social research, either minimizing or boosting this role. Two opposite modes (“theoretical self-binding” and “self-sufficient techniques”) of bringing theory and evidence together are illustrated, and the series of methodological alternatives they imply is discussed. Recognized here as largely Mertonian, the model of theoretical self-binding entails a pre-commitment to theorizing and the conviction that data-gathering techniques cannot run, or even begin to, without an appropriate subject-matter foundation. We conclude by discussing the significance of this approach, at once ill-timed and auspicious in the current end-of-theory climate
Creazione di fibre di diametro 100-200 nm tramite electrospinning di derivati dell’acido ialuronico
No full textLa presente invenzione comprende l’electrospinning di soluzioni di esteri dell’acido ialuronico, e di composti contenenti esteri dell’acido ialuronico ottenuti mediante processo di electrospinning. Questa metodologia consente di realizzare matrici tridimensionali ad elevata porosità ed area superficiale da impiegare nella crescita in vitro di cellule, o nell’ambito della ricostruzione di tessuti danneggiati (tissue engineering)
Shear-induced coalescence in aqueous biopolymer mixtures
No full textThis work is focusedon the investigation of coalescence under shear flow in aqueous mixtures of Na-alginate andNa-caseinate. Shear flow was generatedin a parallel plate apparatus coupledwith an optical microscope. Drop size distribution was measuredas a function of time by computer controlled3D optical sectioning of the sample andof fline image analysis. Automatedproced ures of image analysis, basedon out-of-focus components subtraction andd rop contour detection, were implementedto measure a large number of drops, as requiredto minimize sampling errors. The effects of dispersedphase volume fraction andshear rate on the flow-inducede volution of the drop size distribution were explored. Finally, 3D reconstruction of the locations of the drops within the sample was performed to evaluate possible wall andsed imentation effects
Variazione intra-habitat dei descrittori di funzionamento ecosistemico: efficienza e tassi di decomposizione del detrito in un lago vulcanico (Lago di Vico, VT)
No full textCartografia delle caratteristiche funzionali dell'ecosistema per la realizzazione di una carta della natura multiscalare
No full textFactors affecting macroinvertebrate guild distribution in a Mediterranean intermittent stream: Rio Pula (Sardinia, ITALY).
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
From Background to Default: The Epistemic Role of the Unmarked
No full textThe article treats the epistemic role of the unmarked, with special reference to implicit bia
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