997 resultados para Great Northern Railway


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Selostus: Porkkanan kasvu ja biomassan jakautuminen varastojuuren ja verson välillä pohjoisissa oloissa

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Selostus: Pohjois-Euroopan silikaattisten kalkitusaineiden reaktiivisuus astiakoemenetelmällä ja kahdella pH-staattisella menetelmällä arvioituna

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Avian malaria studies have taken a prominent place in different aspects of evolutionary ecology. Despite a recent interest in the role of vectors within the complex interaction system of the malaria parasite, they have largely been ignored in most epidemiological studies. Epidemiology of the disease is however strongly related to the vector's ecology and behaviour, and there is a need for basic investigations to obtain a better picture of the natural associations between Plasmodium lineages, vector species and bird hosts. The aim of the present study was to identify the mosquito species involved in the transmission of the haemosporidian parasites Plasmodium spp. in two wild populations of breeding great tits (Parus major) in western Switzerland. Additionally, we compared Plasmodium lineages, based on mitochondrial DNA cytochrome b sequences, between the vertebrate and dipteran hosts, and evaluated the prevalence of the parasite in the mosquito populations. Plasmodium spp. were detected in Culex pipiens only, with an overall 6.6% prevalence. Among the six cytochrome b lineages of Plasmodium identified in the mosquitoes, three were also present in great tits. The results provide evidence for the first time that C. pipiens can act as a natural vector of avian malaria in Europe and yield baseline data for future research on the epidemiology of avian malaria in European countries.

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Abstract. Drought leads to a loss of longitudinal and lateral hydrologic connectivity, which causes direct or indirect changes in stream ecosystem properties. Changes in macrohabitat availability from a rifflepool sequence to isolated pools are among the most conspicuous consequences of connectivity loss. Macroinvertebrate assemblages were compared among 3 distinct stream macrohabitats (riffles [R], pools connected to riffles [Pc], disconnected pools [Pd]) of 19 Mediterranean-climate sites in northern California to examine the influence of loss of habitat resulting from drought disturbance. At the time of sampling, 10 sites were perennial and included R and Pc macrohabitats, whereas 9 sites were intermittent and included only Pd macrohabitats. Taxa richness was more variable in Pd, and taxa richness was significantly lower in Pd than in Pc but not R. These results suggested a decline in richness between Pc and Pd that might be associated with loss of connectivity. Lower Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness relative to Odonata, Coleoptera, and Heteroptera (OCH) richness was observed for Pd than R and Pc macrohabitats. Family composition was more similar between R and Pc than between R or Pc and Pd macrohabitats. This similarity may be associated with greater connectivity between R and Pc macrohabitats. Correspondence analysis indicated that macroinvertebrate composition changed along a gradient from R to Pc and Pd that was related to a perennialintermittent gradient across sites. High variability among macroinvertebrate assemblages in Pd could have been related to variability in the duration of intermittency. In cluster analysis, macroinvertebrate assemblages were grouped by macrohabitat first and then by site, suggesting that the macrohabitat filter had a greater influence on macroinvertebrate assemblages than did local site characteristics. Few taxa were found exclusively in Pc, and this macrohabitat shared numerous taxa with R and Pd, indicating that Pc may act as a bridge between R and Pd during drought. Drought is regarded as a ramp disturbance, but our results suggest that the response of macroinvertebrate assemblages to the loss of hydrological connectivity among macrohabitats is gradual, at least in Mediterranean-climate streams where drying is gradual. However, the changes may be more dramatic in arid and semiarid streams or in Mediterranean-climate streams if drying is rapid.

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RESUME :Les fourmis du groupe Formica rufa, ou fourmis des bois, ainsi appelées en raison de leur préférence pour les écosystèmes forestiers, sont parmi les fourmis les plus fascinantes et les plus étudiées d'Europe. Ces fourmis jouent un rôle clé dans la plupart des forêts dans lesquelles elles vivent et sont considérées comme étant les meilleurs bioindicateurs de ces milieux. Pour ces raisons, les fourmis des bois sont protégées par la loi dans de nombreux pays européens, y compris en Suisse. Cependant, malgré leur protection, ces fourmis sont inscrites sur la liste rouge des espèces menacées dans plusieurs pays d'Europe et il est donc indispensable de bien les connaître afin de mieux les protéger.À l'heure actuelle, on considère que le groupe Formica rufa est composé de six espèces distinctes : F. rufa, F. polyctena, F. lugubris, F. paralugubris, F. aquilonia et F. pratensis. Toutefois, malgré la grande quantité d'études effectuées sur ces espèces, la systématique et l'identification des fourmis des bois sont toujours sujettes à discussion. Ceci est essentiellement dû au fait que ces espèces sont morphologiquement similaires et qu'elles sont parfois capables de s'hybrider ou de former des colonies mixtes.Une des conditions fondamentales pour toute étude en biologie de la conservation est l'identification correcte des espèces à protéger. Avec cette étude, nous désirons donc dénouer les problèmes liés à la systématique des fourmis des bois et analyser la diversité de ces espèces en adoptant une approche multidisciplinaire.Nous avons d'abord étudié la distribution des espèces jumelles F. lugubris et F. paralugubris dans les Álpes italiennes en re-analysant l'une des plus grandes collections de références sur ces espèces, déposée à l'Université de Pavie, Italie, et en récoltant de nouveaux échantillons sur le terrain. Nos analyses ont montré que F, paralugubris, décrite récemment et souvent «oubliée »par les chercheurs, est bien présente dans les Alpes et vit souvent en sympathie avec F. lugubris. Ensuite nous avons développé un outil moléculaire basé sur l'ADN mitochondrial pour une identification rapide et efficace de ces deux espèces. Au vu des bons résultats, nous avons étendu nos analyses génétiques (microsatellites) à toutes les espèces du groupe F. rufa, ce qui nous a permis de montrer que les outils moléculaires sont très efficaces pour identifier ces fourmis. En outre, nos analyses ont mis en évidence la présence d'une nouvelle espèce cryptique (appelée F. lugubris-X) au sein du Parc National Suisse. L'existence d'une nouvelle espèce peut avoir une grande influence sur les projets de conservation en faveur de ces espèces. Nous avons donc décidé de confirmer ce résultat avec des analyses comportementales et des analyses chimiques basées sur les phéromones sexuelles des différentes espèces, y compris F. lugubris-X. Les deux approches confirment nos données génétiques et indiquent que F. lugubris-X représente bel et bien une nouvelle espèce de fourmis des bois dans les Alpes Suisses.Les résultats de cette étude ont une grande importance du point de vue de la biodiversité. En plus, ils livrent aux futurs chercheurs des outils fiables pour l'identification des fourmis des bois et ouvrent de captivantes perspectives pour une meilleure protection de ces insectes et, par conséquent, de nos écosystèmes forestiers. .Abstract :Mound building red wood ants (species of the Formica rufa group) belong to one of the most studied groups of ants in Europe and have fundamental roles and positive effects in forested habitats of the northern hemisphere. In addition, they are considered among the most promising bioindicators of forest ecosystems. Because of their importance, these ants are protected by law in many European countries, including Switzerland. However, despite this protection, they are included on the red list of threatened species edited by the International Union for Conservation of Nature (IUCN) and on the red list of some particular countries like Switzerland. Because of their similar morphology and a high intraspecific variability, the morphological identification of these species can be quite complicated. In addition, they are sometimes able to hybridize or to form mixed colonies. Consequently, the taxonomy of this group of ants has been much debated during the past decades. Based on a phylogenetic study, today the group is considered to count six species in Europe: F. rufa, F. po/yctena, F. lugubris, F. paralugubris, F. aquilonia and F. pratensis. Nevertheless, the taxonomy of the group is often neglected mainly due to the lack of reliable and easy to use identification methods.Considering the importance of correct species assessment in conservation biology, in this study we want to disentangle the taxonomical difficulties within the Formica rufa group and to clarify the diversity of these protected ants, by using an integrative approach.We first analyzed the distribution of .the sibling species F. lugubris and F. paralugubris in the Italian Alps by collecting new samples on the field and by examining one of the major red wood ant collections, which is deposited at the University of Pavia, Italy. After that, we developed a molecular tool based on mitochondria) DNA, which provides a reliable and easy-to-use technique for the identification of F. lugubris and F. paralugubris. Afterwards, we extended the use of molecular markers for species identification to the whole F. rufa group and made a microsatellite analysis. Results confirm that molecular markers are consistent tools for species identification and that the six known species represent six different genetic pools. In addition, genetic data highlighted the existence of a new cryptic species in the Swiss Alps, called Formica lugubris-X.The presence of a new species can have a great influence on future conservation plans in favour of these protected ants and consequently for forested habitats. We therefore completed molecular data by behavioural (pupae recognition) and chemical analyses based on six pheromones of the entire F. rufa group. Both approaches are in accordance to genetic results and confirm that F. lugubris-X really represents a new cryptic species of red wood ant within the Swiss National Park (Eastern Swiss Alps).Results obtained in this study have a great importance in terms of biodiversity. Moreover, they provide important taxonomical information, reliable tools for species identifications and future perspectives for a consequent conservation of red wood ant species.

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This is a story about a highway project near the small town of Wever, Iowa, and an American Indian village that existed at the location prior to the Europeans' arrival. The culture that lived in this village existed in a 10 state region of the Upper Midwest and may have been the ancestors of tribes living in the Midwest when European explorers entered the region. An archaeological recovery of information from the site was undertaken by the Iowa Department of Transportation because four-lane construction of U.S. 61 could not be accomplished without destroying most of the site. This site proved to be one of the richest archaeological finds in the State of Iowa. ǂc Iowa Department of Transportation.

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A new genus (Triassiphaeodina gen. nov.) and two new species (Medusetta japonica sp. nov. and Triassiphaeodina niyodoensis sp. nov.) of Late Triassic (Rhaetian) phaeodarian Radiolaria are described from a phosphatic nodule found in melange rocks of the Northern Chichibu Belt, Shikoku, Japan. The Rhaetian age of the nodule and of the phaeodarian new taxa is based on co-occurring Polycystina Radiolaria, including Bipedis acrostylus Bragin, Livarella densiporata Kozur and Mostler, Fontinella primitiva Carter, and Ferresium sp. A of Carter (1993). This finding shows that phaeodarian Radiolaria were already represented in Late Triassic oceans, with morphologies similar to those known in the Late Cretaceous and Cenozoic, from which they have previously been reported. The new taxa described herein represent the oldest known phaeodarian fossils.

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Tiivistelmä: Typpioksiduulivirrat suunnitellun Vuotoksen tekojärven alueen soilta

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This article summarizes the different stages of research for the development of medical interventions and their specific characteristics in terms of design, population, resources, importance of results and scientific interest. The emphasis is focused on the two final stages of development, the effectiveness and the impact. An example from our own experience is given to illustrate the reduction of the effect of an intervention against malaria in young children at different stages of the development of the intervention, and the parallel decrease of the recognition by the scientific community of the importance of these results.

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The Paleozoic stratigraphic succession in the Catalonian Coastal Ranges spans the interval from Cambrian(?) to Carboniferous, with only one break, separating the pre-Carboniferous part of the sequence from the Carboniferous. The oldest rocks exposed form a sequence of schists, fine grained sandstones, gneisses (laminar pre-Hercynian intrusions), marbles, orto- and para-amphibolites and calcsilicate rocks. comparison with other localities iuggests an Early Cambrian age (or perhaps in part older). Upwards the sequence becomes more monotonous andconsists only of schists (or slates where themetamorphic grade is lower) and thin fine-grained sandstone layers (Cambrian-Ordovician). Still higher in the sequence, an altemation of greywackes and slates is found, with interlayered mud-supported conglomerates at its lower part and acid volcanic rocks which occur throughout the whole sequence. This part of the sequence has provided the oldest faunas known in the Catalonian Coastal Ranges, which indicate the Caradoc. Finally, in its uppermost part, the Ordovician sequence contains some thin limestone layers that contain Ashgill faunas. The Silurian, from Llandovery to Lower Ludlow, consists of black graptolitic shales with dolerite sills, whilst the upper Ludlow, Pridolian and Devonian consist of nodular limestones and marls withpelagic and hemipelagic faunas. The youngest Devonian faunas found correspond in general to the Emsian. The existence of a gap at this point of the sequence suggests the possibility that part of the Devonian could have been eroded. The Carboniferous is characterized by a thick culm sequence (Visean to Westphalian?), resting on thin chert and limestone layers (Tournaisian and Visean). A comparison with neighbouring areas shows a similarity regarding succession and facies with other Paleozoic massifs around the Western Mediterranean.