Search results for "Rust"

Variazioni morfologiche nel corso dell'ontogenesi in individui di Bathyporeia guilliamsoniana (Crustacea: Amphipoda).

2011

Differentiation in morphology and habitat partitioning of genetically characterized Gammarus fossarum forms (Amphipoda) across a contact zone

2000

Evolutionary processes do not affect all character types equally. Depending on environmental effects, morphological and ecological evolution may be uncoupled from molecular evolution. A natural contact zone between two forms of the amphipod Gammarus fossarum was used to assess the levels of differentiation in genetic, morphological and habitat characters. About 50 individuals per population were analysed for six enzyme loci in 72 populations and four size-standardized morphometric traits in a subset of 32 populations. Nine environmental parameters per population were used to characterize the habitat. All three character sets revealed significant divergences between G. fossarum forms. The ea…

Mountain-building under extension

2013

A mechanism is presented which explains how intra-continental rifting can cause large topographic uplift. The effect is sufficient to account for the uplift of rift flanks and the very high and strongly localized uplift of the Rwenzori horst in the Western Branch of the East African Rift System. We propose that the uplift is generated by crustal bending, which is caused by a misfit of the lateral tensile stress between the upper and middle crust. The misfit is a function of different yield mechanisms when the upper crust breaks whereas the middle crust flows. Two independent numerical schemes confirm the suggested uplift mechanism. Both models—a 2 and 2.5 D elastoplastic lattice-particle mo…

Fine Determination of the Molt Cycle Stages in Orchestia cavimana Heller (Crustacea: Amphipoda)

1986

ABSTRACT The successive stages of the molt cycle of the terrestrial crustacean amphipod Orchestia cavimana are finely described and illustrated in order to give precise reference marks for experimental, physiological, and biochemical studies. The method of determination, very rapid and easy, is based upon the observation of the morphogenesis of the dactylopodite and the propodite from the third pereiopod. The events of the early morphogenesis of the claw from the dactylopodite divide the intermolt period C into four stages. The formation of spines and the secretion of the epicuticle and then the procuticle at the level of the propodite divide the premolt period into seven stages. The entire…

Variations in haemolymph ionized calcium concentrations in the crustacean Orchestia cavimana during a moult cycle

1993

Abstract Measurements of ionized calcium concentration in the haemolymph of the semi-terrestrial crustacean Orchestia cavimana were taken during the 14 successive moulting stages by ion-selective electrode direct potentiometry on pooled samples. Ionized calcium showed major variations associated with the moult cycle. Titres were low and relatively stable in intermoult and early premoult, then progressively increased during mid and late premoult to reach maximal values just at exuviation, and rapidly fell down during the postmoult. The variations of the ionized fraction showed a close correlation with those of the calcaemia (= total fraction), suggesting the presence of efficient haemolympha…

Helminth infestation of three fishes (Serranus scriba, Mullus surmuletus, Scorpaena porcus)from a coastal seaground in the Gulf of Palermo (Tyrrhenia…

1997

Abstract The results of a year's survey on the parasitic infestation of the gastrointestinal tract of three species of benthic fish, namely Serranus scriba, Mullus surmuletus, and Scorpaena porcus, living in a restricted coastal seaground in the N/W sector of the Gulf of Palermo, are reported and critically discussed. Fish populations were sampled monthly by means of a trammel net, according to the local fishing usage. As many as nine helminth species, five of them trematodes and four nematodes, were collected from the gastrointestinal tract of 625 individuals. Infestation was most intense in M. surmuletus, with a peak in the spring. S. scriba was especially parasitized during the spring an…

Building and Maintaining the Common Ground in Web-Based Interaction

2002

In this paper, the main purpose is to explore how participants establish and maintain the common ground in the computer-based conferences. Previous studies assume that before the participants can reach the deeper level interaction and learning, they have to gain an adequate level of common ground (Dillenbourg, 1999; Baker et al., 1999; Veerman, 2000). Subjects were 68 pre-service teachers and 7 mentors from three universities who participated in the web-based conferencing course for eight weeks. The results assume that in deeper level discussions it is essential that participants, especially fellow students did give not only the evidence about their own understanding by using written feedba…

Understanding melt generation beneath the slow-spreading Kolbeinsey Ridge using 238U, 230Th, and 231Pa excesses

2011

International audience; To examine the petrogenesis and sources of basalts from the Kolbeinsey Ridge, one of the shallowest locations along the global ridge system, we present new measurements of Nd, Sr, Hf, and Pb isotopes and U-series disequilibria on 32 axial basalts. Young Kolbeinsey basalts (full-spreading rate = 1.8 cm/yr; 67 degrees 05'-70 degrees 26'N) display ((230)Th/(238)U) 1 with ((230)Th/(238)U) from 0.95 to 1.30 and have low U (11.3-65.6 ppb) and Th (33.0 ppb-2.40 ppm) concentrations. Except for characteristic isotopic enrichment near the Jan Mayen region, the otherwise depleted Kolbeinsey basalts (e. g. (87)Sr/(86)Sr = 0.70272-0.70301, epsilon(Nd) = 8.4-10.5, epsilon(Hf) = 15…

En etsi valtaa, loistoa .. : amerikkalaiseen asejärjestöön perustuvaa tutkimusta vallan suhteellisuudesta ja sen määrittelemisen ongelmallisuudesta

2006

Satisfaction and frustration of autonomy and relatedness needs: Associations with parenting dimensions and psychological functioning

2018

Framed from Basic Psychological Needs Theory (Ryan and Deci in American Psychologist 55:68–78; Ryan, Deci, American Psychologist 55:68–78, 2000) and Kagitcibasi’s Autonomous-Related Self Theory (Journal of Cross-Cultural Psychology 36:1–20; Kagitcibasi, Journal of Cross-Cultural Psychology 36:1–20, 2005), the study examined the relationships of adolescents’ satisfaction and frustration of autonomy and relatedness, with (a) adolescents’ perception of mother’s and father’s psychological control and autonomy support, and (b) adolescents’ self-acceptance and anxiety. Participants were 556 adolescents (M = 17.25, SD = 0.92). Path analysis showed more significant associations of autonomy support …