Extrasporogonic stages of Sphaerospora sp. from the kidneys of Atlantic salmon (Salmo salar L.) were successfully transmitted via intra-peritoneal injection to naive Atlantic salmon and brown trout (Salmo trutta L.). Rainbow trout (Oncorhynchus mykiss Walbaum) could not be infected in this way. Transmitted extrasporogonic stages continued their development to form sporogonie stages and mature spores in the kidney tubules. Extrasporogonic stages, sporogonie stages and mature spores of the parasite in both experimentally infected hosts were morphologically identical to the equivalent stage in naturally infected Atlantic salmon, although minor differences were seen in spore dimensions. A farm-based exposure experiment confirmed the susceptibility of brown trout to the salmon Sphaerospora, These results are consistent with the view that the salmon Sphaerospora is Sphaerospora truttae Fischer-Scherl, El-Matbouli et Hoffmann, 1986. The parasite is redescribed according to the guidelines of Lom and Arthur (1989) since details of extrasporogonie stages, the ultrastructure of extrasporogonic and sporogonie stage development, and of the parasite’s epidemiology are known from Atlantic salmon but not from other reports.
The present study is focusing on the transmission of the monogenean ectoparasite Gyrodactylus salaris Malmberg, 1957, a major pathogen on natural populations of Norwegian Atlantic salmon, Salmo salar L. In laboratory experiments the transmission rate of G. salaris after direct host to host contact was positively correlated with water temperature (1.2, 4,7 and 12.2°C). The transmission of detached G. salaris in the planktonie drift was studied in field experiments where salmon parr were individually isolated for 24 hours in small wire mesh cages suspended in the water column. Ten out of 157 salmon parr (prevalence 6.4%, mean intensity 1.0) contracted G. salaris infections after this exposure. Furthermore, 200 uninfected marked salmon parr were released into the same area of the river. After 24 and 48 hours, respectively 18 and 19 marked parr were caught by electro-fishing. The prevalence of G. salaris was 44.4% (mean intensity 1.9) after 24 hours, rising to 57.9% (mean intensity 2.3) after 48 hours. Gyrodactylids have no specific transmission stage or swimming ability, but detached G. salaris drifting in the water column were found to infect salmon parr. However, the transmission rate was markedly higher to free-living fish, suggesting that transmission routes such as indirect transmission from the substrate or direct contact transmission from infected live and/or dead fish, are relatively more important than transmission by drifting detached parasites.
Transnationalism and diaspora are concepts that are often intertwined but nonetheless differ. This article examines the link between transnationalism and integration processes among return migrants from the Armenian diaspora and examines the role social networks play in integration in Armenia. Returnees to Armenia can be divided into those who have returned from the Armenian diaspora (second and subsequent generations of migrants) and those who emigrated from Armenia and decided to return. This is reflected in the literature as a distinction between the 'old' and the 'new' Armenian diaspora, the latter having emerged in the 1990s. Before returning, both groups maintained ties with people in Armenia and may differ only by the extent and frequency of use of these ties. These ties can then accompany them when they return to Armenia and help them to (re-)integrate. The integration of returnees has its own specifics, compared to the integration of migrants, and may not be as simple as it might seem. This article focuses on the transnational ties of 23 migrants of Armenian descent who returned to Armenia after a long time abroad and draws on original research on return migration in Armenia conducted in 2016 and 2018. Semi-structured interviews with returnees revealed that their participation in the labour market is instrumental to their integration into mainstream society, and their work may involve transnational activities. The article shows the different opportunities that weak and strong ties provide returnees and that may facilitate their integration. Weak ties on a local level are crucial for returnees to be able to reintegrate and fully participate in life in Armenia. The article aims to understand the return strategy as one of the migration options that may or may not be permanent. A return may be followed by re-migration, under certain conditions and if obstacles to sustainable reintegration, and the article also explores the motivations for re-migration.
This article deals with Ukrainian student migration and the convergence of integration and transnationalism. Its main focus is the self-identification of young Ukrainians studying in the Czech Republic. The authors explore and describe international students' different integration and transnational dispositions and also discuss whether these dispositions could be seen as part of antagonistic or synergetic processes. The interconnection between transnationalism and integration is widely discussed in both sociological and anthropological literature, and most scholars identify them as synergetic processes. In the case of Ukrainian students in the Czech Republic, however, the authors argue that these processes can be understood as both synergetic and antagonistic because what matters is the students' self-identification. Most of the analysis presented in this article is based on in-depth interviews with Ukrainian students conducted between 2012 and 2019. The results of qualitative research are also compared to and discussed in relation to the findings from an on-line survey conducted among 258 Ukrainian students in 2018. The article suggests that Ukrainian students themselves could incline in both directions, towards an antagonistic and a synergetic understanding of integration and transnationalism, because it depends on their self-expressed dispositions. However, most participants most of the participants in the research express the synergy.
The article is a reflection on the neoliberal knowledge economy, the traffic in antiracist feminist theory, and the way my work has been read (lost or found in translation) and has crossed geopolitical and racial/cultural borders. It comments as well on the development of my intellectual project in relation to my location in the US academy and the intellectual and political communities that have made the work possible. The larger frame I seek to examine using responses to my work in three sites – Sweden, Mexico, and Palestine – is the way feminist, postcolonial, and antiracist theory emerges from a particular geopolitical, intellectual space; the way it enacts crossings; and the way it is trafficked, consumed, and understood in different geographies. Given the global and domestic shifts in social movements and transnational feminist scholarly projects over the past three decades, my major concern pertains to the depoliticization of antiracist feminist/women-of-color/transnational feminist intellectual projects in neoliberal, national-security-driven geopolitical landscapes.
Transparentní keramika se v laserové technice využívá jako matrice aktivních laserových prostředí vysokovýkonových laserů, kde se začala prosazovat od začátku milénia. Díky svým jedinečným vlastnostem je atraktivní alternativou monokrystalů a skel, kdy nachází využití v široké škále oborů a aplikací zahrnujících optiku, vojenství, medicínu, detektory záření a další., Transparent ceramics have been used as matrices for laser gain media of high power lasers since the beginning of this millennium. Thanks to its unique qualities it has become an attractive alternative to glasses and single crystals, finding applications in the field of optics, defence, medical facilities, radiation detectors and many others., Samuel Paul David, Petr Navrátil, Martin Hanuš, Venkatesan Jambunathan, Martin Divoký, Antonio Lucianetti, Tomáš Mocek., and Obsahuje bibliografické odkazy
Soil water availability, nutrient supply and climatic conditions are key factors for plant production. For a sustainable integration of bioenergy plants into agricultural systems, detailed studies on their water uses and growth performances are needed. The new bioenergy plant Igniscum Candy is a cultivar of the Sakhalin Knotweed (Fallopia sachalinensis), which is characterized by a high annual biomass production. For the determination of transpiration-yield relations at the whole plant level we used wicked lysimeters at multiple irrigation levels associated with the soil water availability (25, 35, 70, 100%) and nitrogen fertilization (0, 50, 100, 150 kg N ha-1). Leaf transpiration and net photosynthesis were determined with a portable minicuvette system. The maximum mean transpiration rate was 10.6 mmol m-2 s-1 for well-watered plants, while the mean net photosynthesis was 9.1 µmol m-2 s-1. The cumulative transpiration of the plants during the growing seasons varied between 49 l (drought stressed) and 141 l (well-watered) per plant. The calculated transpiration coefficient for Fallopia over all of the treatments applied was 485.6 l kg-1. The transpiration-yield relation of Igniscum is comparable to rye and barley. Its growth performance making Fallopia a potentially good second generation bioenergy crop.