Search results for "Contact zone"
showing 7 items of 7 documents
Gene flow in the European coal tit, Periparus ater (Aves: Passeriformes): Low among Mediterranean populations but high in a continental contact zone
2018
Abstract Extant phylogeographical patterns of Palearctic terrestrial vertebrates are generally believed to have originated from glacial range fragmentation. Post-Pleistocene range expansions have led to the formation of secondary contact zones among genetically distinct taxa. For coal tits (Periparus ater), such a contact zone has been localized in Germany. In this study, we quantified gene flow between Fennoscandian and southern European coal tits using a set of 13 microsatellite loci. STRUCTURE analysis revealed four genetic clusters, two occurring on Mediterranean islands. German populations were genetically admixed but introgression of southern alleles was evident for Fennoscandian popu…
Spreading introgression in the wake of a moving contact zone
2006
An increasing number of studies describe moving hybrid zones. This raises the issue of their actual frequency and emphasizes the need for methods that enable the detection of zone movements without historical records. Asymmetric introgression, usually considered as a signature of geographical shift, might be misleading when applied to mitochondrial or potentially non-neutral markers. We investigated mitochondrial and genomic introgression, using 30 AFLP derived markers, in a well-documented moving avian contact zone between two warblers. We found no instances of cross-species transmission of mitochondrial DNA but we detected nuclear introgression. Introgression levels were higher in the exp…
Studies on mechanism and physico-chemical parameters at the origin of the cement setting. I. The fundamental processes involved during the cement set…
1995
Abstract The mechanical evolution and the structure of the cement paste have been analysed in relation with the chemical evolution of the system. The setting process can be described as following two fundamental steps: the coagulation of cement grains during the first minutes following the mixing, and the rigidification of the coagulated structure which arises simultaneously with the acceleration of the hydrates formation During the coagulation step, the structure formed is proved to be mechanically reversible. The rigidification of the coagulated structure is provided by the hydrates formation in the contact zone. The increase of the paste cohesion at this stage is proportional to the quan…
Afroperipheral indigeneity in Wayde Compton’s The Outer Harbour
2021
Black Canadian writer Wayde Compton’s short story collection The Outer Harbour (2015) is located in the Afroperiphery of British Columbia which stands as a ‘contact zone’ that enables the alliances between Black and Indigenous peoples and also establishes a fecund ground of possibilities to emphasize the way in which crossethnic coalitions and representations reconsider imperial encounters previously ignored. The stories participate in the recent turn in Indigenous studies towards kinship and cross-ethnicity to map out the connected and shared itineraries of Black and Indigenous peoples and re-read Indigeneity in interaction. At the same time, the stories offer a fresh way to revisit Indige…
Influence of machining conditions on friction in metal cutting process – A review
2019
This paper presents a range of variable machining factors which influence substantially friction directly or by the tool wear developed in the cutting zone. The group of direct factors include the workpiece and cutting tool materials coupled, the cutting/sliding velocity, cooling media supplied to the tool-chip contact zone, modification of the tool contact faces by micro-texturing. Special attention was paid to the tool wear evolution and its pronounced effect on changes of the contact conditions.
Developing Intercultural Mindedness through an Experiential Learning Activity—A Case Study from Singapore
2022
Recent incidents of alleged racism worldwide amid the COVID-19 pandemic have challenged us to ponder on the meaning and importance of intercultural education. However, it can be difficult to understand the ways in which intercultural discourse can be beneficial for learning, as well as prepare young people to act against racism and inequalities to work towards a more sustainable future. This study presents analysis of learning materials from a case study conducted in one secondary school in Singapore. The objective of the activity is for students to engage in intercultural learning by participating in walking trails with different themes in a few neighborhoods, to learn more about the histo…
Calls of the Jungle Crow (Corvus macrorhynchos s.l.) as a taxonomic character
2000
A discriminant analysis of the call structure completely separates threeCorvus taxa (levaillantii andjaponensis of the ‘macrorhynchos group’,splendens) inhabiting the southern slopes of the Himalayas (Nepal, Kashmir). The acoustic differences are considered taxonomically relevant, indicating species boundaries. Therefore the Jungle Crows of lower and upper Nepal (contact zone at around 2,000 m) are assigned to two biospecies (C. japonensis andC. levaillantii), as is consistent with morphological, ecological and parasitological data. It appears possible to extrapolate the findings regarding call structure to the systematics of other ‘macrorhynchos’ populations as distant as the Russian Far E…