1,721,236 research outputs found
Sessile and non sessile morphs of Geodia cydonium (Jameson) (Porifera, Demospongiae) in two semi-enclosed Mediterranean bays
No full textMorphological plasticity and ecological aspects of the demosponge Geodia cydonium (Jameson) were studied from seasonal samples collected over 1 year in two semi-enclosed Mediterranean bays of the Southern Italian coast (Marsala lagoon and Porto Cesareo basin). Sponge specimens present two morphs: sessile and nonsessile, both of which showed constant size distribution and density over the studied year. Sessile specimens were larger in size than non-sessile ones. This feature is particularly evident at Porto Cesareo, where these sponges have a more compact skeletal network than at Marsala (evident both in the cortical spicule size and sponge silica content). Sessile specimens adhere to hard rocky substrates (Porto Cesareo) or phanerogam rhizomes (Marsala); non-sessile ones occur on soft bottom areas. Several morphological and structural features of the non-sessile forms differ in the two environments, but the
difference in body shape seems to play the most relevant role in enhancing the colonization of incoherent substrates.
Indeed, at Marsala, where the large amount of silt and clay determines the occurrence of a markedly reduced anoxic layer just below the surface of the sediment, non-sessile specimens of G. cydonium are fairly spherical and thus able to roll, dragged by slow circular currents. In addition, the usual association with the red
alga Rytyphlo ̈ ea tinctoria, which almost constantly
forms a thick and continuous layer around the sponge,
allows them to avoid contact with the substrate. The
non-sessile specimens from Porto Cesareo inhabit sandy
soft bottoms and are flattened. In such an environment,affected by moderate wave turbulence, the flattened shape widens the contact surface between the body and the substrate, thereby reducing the risk of stranding. The evident signs of abrasion, provided by scanning electron
microscopy investigations, on both cortical spicules and
outermost sponge surface suggest that sponges rub on
the bottom. Sediment, epibiontic organisms, and the
phanerogam leaves protect this sciaphilous sponge from
high solar radiation, allowing the specimens to live in these shallow environments
Modified Clay and Zeolite Nanocomposite Materials: Environmental and Pharmaceutical Applications
No full textModified Clay and Zeolite Nanocomposite Materials: Environmental and Pharmaceutical Applications retraces the most important knowledge gaps that the scientific community is facing, including a drawback of real-world applications. This valuable resource explores the novel applications of this group of nanomaterials that can be suitably surface-modified to obtain properties that can be applied in environmental and pharmaceutical fields. For example, modification with surfactants has given new motivation to the study of these materials by producing an inversion in the ion exchange behavior from cationic to anionic. This strategy has paved the way for new uses highlighted in this timely resource
A 3-year investigation of sexual reproduction in Geodia cydonium (Jameson 1811) (Porifera, Demospongiae) from a semi-enclosed Mediterranean bay
No full textThe reproductive cycle of Geodia cydonium in a semi-enclosed Mediterranean bay (Porto Cesareo, SW Apulia) was studied with monthly frequency over a 3-year period. The investigation was carried out by utilizing a technique consisting of tagging ten individuals with a PVC stick and cutting off, by means of a metal cork borer, small samples (cylinders about 5 cm(3) in volume) from each of them for histological analysis. Sexual reproductive elements were detected in all individuals, but in the third year some specimens showed reduced reproductive activity or complete infertility. Spermatogenesis occurred in a short period (from June to August) whereas oogenesis lasted longer (from spring to late summer). Spermatic cysts occurred when the frequency of specimens with oocytes reached its maximum values. A relationship between water temperature and the onset of gamete differentiation was observed. G. cydonium is here confirmed oviparous and gonochoric with a sex ratio in favour of the females. However, in contrast with current literature on Porifera-which suggests that only a limited number of sponges, all belonging to the same species are sexually active-the sexual reproduction of this species involves all the examined individuals. This finding can be explained by the methodological approach used in this research, which differs from the traditional way of assessing the sponge reproductive cycle by analysing randomly collected specimens within a population. The study of a series of individuals over time represents a better "model technique" for investigating sponge sexual reproduction and the effect of environmental parameters on gamete differentiation
Sleeping over moral dilemmas modulates utilitarian decision-making
Full text linkMoral decision-making depends on the interaction between emotional and cognitive control processes, which are also affected by sleep. Here we aimed to assess the potential role of sleep in the modulation of moral decisions over time by testing the change in behavioral responses to moral dilemmas over time (1 week). Thirty-five young adults were tested twice, with one week between the sessions. In each session, participants were presented with 24 sacrificial (12 Footbridge- and 12 Trolley-type) and 6 everyday-type moral dilemmas. In sacrificial dilemmas, participants had to choose whether or not to kill one person to save more people (utilitarian choice), to judge how morally acceptable the proposed solution was, and how they felt in terms of valence and arousal during the decision. In everyday-type dilemmas, they had to decide whether to pursuit moral violations involving dishonest behavior. Between the sessions, the participants’ sleep pattern was assessed via actigraphy. We observed that participants reduced the utilitarian choices in the second session, and this effect was more pronounced for the Trolley-type dilemmas. We also showed that after a week participants judged the utilitarian choices as less morally acceptable, but there was no change in self-reported emotional reactivity (i.e., valence, and arousal). Moreover, sleep efficiency was mildly negatively associated with the changes in decision choices and moral acceptability for the Footbridge-type dilemmas. Taken together, our data suggest that dealing with a moral situation engages several interacting factors that seem to go beyond the competing roles of cognitive and emotional processes
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
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