Search results for "Axon"
showing 10 items of 2126 documents
Tooth replacement rates in early chondrichthyans: a qualitative approach
2009
The continuous replacement of teeth throughout their lifetime is a common characteristic of most chondrichthyans. This process was already present in the earliest representatives of the group. It has been well established that different species of extant sharks show rapid tooth replacement rates; however, some authors have suggested that in early chondrichthyans this rate might have been much slower. Here we present a qualitative approach to analyse tooth replacement rates in the Early Devonian shark Leonodus carlsi, the earliest tooth-bearing shark known to date. For this, we have examined 1,103 isolated teeth from Celtiberia, Spain. Our study provides strong evidences of an extremely slow…
Living Coccolithophores from the Gulf of Sirte (Southern Mediterranean Sea) during the summer of 2008
2012
The Gulf of Sirte is a largely unexplored area in the southernmost Mediterranean Sea.We are presenting here 2008 summer data on the distribution pattern of living coccolithophores, a main phytoplankton calcifying group, in 105 samples from 20 stations. The survey includes coastal and offshore stations, enabling us to provide indications on the dynamics of phytoplankton productivity in relation to oceanographic processes. The total coccosphere concentrations show higher values in the offshore stations and lower ones for coastal sites. Umbellosphaera tenuis, Emiliania huxleyi, Florisphaera profunda, Syracosphaera pulchra HOL (Calyptrosphaera oblonga) and Rhabdosphaera spp. dominate the assemb…
Typologia województw pod względem ekonomicznego zrównoważenia rolnictwa
2016
Celem pracy jest próba oceny poziomu ekonomicznego zrównoważenia rolnictwa w Polsce na podstawie wybranych wskaźników. Ideą rolnictwa zrównoważonego jest zracjonalizowanie intensywności produkcji, co wpływa na jakość środowiska naturalnego. Zasady zrównoważonego rozwoju zrodziły się z potrzeby uwzględnienia w7 procesach gospodarowania interesów obecnych i przyszłych pokoleń, zwłaszcza pod kątem zachowania walorów środowiska. Pojęcie zrównoważonego rozwoju rolnictwa ma charakter wielopłaszczyznowy i wieloaspektowy. Początki postrzegania rozwoju rolnictwa poprzez pryzmat ekonomicznych korzyści oraz uwzględnianie ekologii w produkcji, w krajach Unii Europejskiej, sięgają lat 70. minionego wiek…
Bailiaspis (Trilobita) with English affinities from the Mansilla Formation (Cambrian Series 3 of the Iberian Chains; NE Spain)
2020
A new study of the trilobite record in the Mansilla Formation (Iberian Chains, NE Spain) has led to the discovery of the presence of Bailiaspis aff. tuberculata, B. cf. tuberculata and Bailiaspis sp., the first certain citation of this genus in the Mediterranean subprovince. The age of the findings extends from Eccaparadoxides asturianus Zone (upper Leonian) to the lowermost Badulesia tenera Zone (lower Caesaraugustan), which correspond to the upper part of Stage 5 of Cambrian Series 3 and, probably, the lowermost Drumian. The specimens show the cranidial anterior border expanding backwards, forming a plectrum that is characteristic of Bailiaspis. The main characters of the three taxa inclu…
A quoi sert l'audit environnemental ?
2013
International audience; L'objectif de cet article est de comprendre le rôle de l'audit dans le domaine environnemental afin d'en proposer une taxonomie. A partir d'une grille d'analyse découlant des théories néo-institutionnelle et des parties prenantes, cette taxonomie est obtenue en étudiant les pratiques d'audit d'une entreprise française proactive en matière environnementale. Les résultats montrent qu'en l'absence de réglementation en matière de vérifications environnementales, l'audit peut remplir plusieurs rôles dans ce domaine : vérification de la conformité réglementaire, identification des aspects environnementaux d'un site industriel, analyse de cycle de vie d'un produit, vérifica…
Best Practices for International eSourcing of Software Products and Services from the Service Providers' Perspective
2015
This research analyzes how eSourcing service providers can execute the Information and Communications Technology-enabled international sourcing of software-intensive systems and services (eSourcing) effectively. The extant literature falls short of providing a detailed enough set of best practices and supporting classes of information systems to help providers to manage and deliver effective services. This research presents a set of best practices for international eSourcing service providers to facilitate the execution, improvement, and management of international eSourcing services. The practices help providers to establish and execute a mature eSourcing life-cycle in order to overcome th…
Genome size evolution in macroparasites.
2014
Reduction in genome size has been associated not only with a parasitic lifestyle in intracellular microparasites but also in some macroparasitic insects and nematodes. We collected the available data on genome size for flatworms, annelids, nematodes and arthropods, compared those with available data for the phylogenetically closest free-living taxa and found evidence of smaller genome sizes for parasites in six of nine comparisons. Our results suggest that despite great differences in evolutionary history and life cycles, parasitism as a lifestyle promotes convergent genome size reduction in macroparasites. We discuss factors that could be associated with small genome size in parasites whic…
Sisubiotus hakaiensis sp. nov. (Tardigrada, Macrobiotidae), a new tardigrade species from Calvert Island (British Columbia, Canada)
2022
Tardigrades reports from British Columbia (Canada) trace back to 1908 and numerous species have been recorded from this region, despite the relatively few published sampling studies. We describe by integrative taxonomy (light microscopy morphology, morphometrics, and DNA sequencing) a new tardigrade species, Sisubiotus hakaiensis sp. nov. from the British Columbia central coast. The new species has been found in moss collected from a vertical rock outcrop near the Hakai Institute Calvert Island Field Station. Sisubiotus hakaiensis sp. nov. differs from all the other known species in the genus by the presence of a labyrinthine layer inside the egg process walls, whereas no consistent differe…
A new species of Silene sect. Dipterosperma (Caryophyllaceae) from Sicily
2012
Silene kemoniana, a new species of the section Dipterosperma from NW Sicily, is described and illustrated. It is a therophyte that occurs in mountains near Palermo, where it grows on Mesozoic limestones in xerophilous garigues. Its relationships with S. colorata and allied species are also examined. A key of the species belonging to sect. Dipterosperma is provided. Se describe e ilustra Silene kemoniana, una nueva especie del NW de Sicilia perteneciente a la sección Dipterosperma. Se trata de un terófito que habita en algunas montañas próximas a Palermo, donde crece sobre calizas mesozoicas entre matorrales mediterráneos xerófilos. Se estudian sus relaciones con S. colorata y otras especies…
Sensitivity of bipartite network analyses to incomplete sampling and taxonomic uncertainty
2023
Bipartite network analysis is a powerful tool to study the processes structuring interactions in ecological communities. In applying the method, it is assumed that the sampled interactions provide an accurate representation of the actual community. However, acquiring a representative sample may be difficult as not all species are equally abundant or easily identifiable. Two potential sampling issues can compromise the conclusions of bipartite network analyses: failure to capture the full range of interactions (sampling completeness) and use of a taxonomic level higher than species to evaluate the network (taxonomic resolution). We asked how commonly used descriptors of bipartite antagonisti…