51 research outputs found
A multi-mode imager
Conventionally, the acquisition of bright-field images and fluorescence images using the same device has required an imager equipped with a mechanical movement, able to mechanically interchange filters in-between a sample stage and an imaging element, dependent on whether a bright-field or a fluorescence exposure is being made. The present application discusses a multi-mode imager (30) comprising a bright-field light source (32) and a first excitation light source (34) for exciting fluorescent dyes in a biopsy sample (31). An optical filter arrangement (36, 36a, 36b, 36c) is provided enabling the multi-mode scanning of the biopsy without the need to use a mechanism for interchanging filters
Quartz SAR optically stimulated lumines-cence (OSL) dating of sands from Ulbjerg Klint, Central Jutland, Denmark
This report concerns optically stimulated luminescence (OSL) investigations of a soil profile at Ulbjerg Klint, Central Jutland, Denmark. At this site, a minor landslide had exposed some unusually clear plough marks, which might contribute to the understanding of the first use of the mould-board plough in southern Scandinavia. The aims were first to date the plough marks, and secondly to date the oldest phase of the sedimentary archive of this site, with a remarkable thick sequence of aeolian sands with high potentiale for archaeological and paleo-climate studies. The report presents the OSL method, the results, a discussion and a conclusion, while the appendixes contains analytical description and a detailed soil profile and sampling description. Combined, the determined OSL ages reveal that over a 2500 years period the vegetation on this exposed coastal cliff was removed several times with episodes of drifting sand as a consequence. The first aeolian sand layer is dated at or slightly after 5th century BCE, i.e. around the transition between the Danish late Bronze Age to the pre-Roman Iron Age. The aeolian sand layer with the clear plough marks is from the 17th century CE, i.e. in the Little Ice Age. Due to the limited number of OSL dated samples, no additional climatic or land use indications could be established
Monitoring a Norwegian freshwater crayfish tragedy: eDNA snapshots of invasion, infection and extinction
1. The European noble crayfish Astacus astacus is threatened by crayfish plague caused by the oomycete Aphanomyces astaci, which is spread by the invasive North American crayfish (e.g. signal crayfish Pacifastacus leniusculus). Surveillance of crayfish plague status in Norway has traditionally relied on the monitoring survival of cageâheld noble crayfish, a method of ethical concern. Additionally, trapping is used in crayfish population surveillance. Here, we test whether environmental DNA (eDNA) monitoring could provide a suitable alternative to the cage method, and a supplement to trapping. 2. We took advantage of an emerging crayfish plague outbreak in a Norwegian watercourse following illegal introduction of diseaseâcarrying signal crayfish, and initiated simultaneous eDNA monitoring and cageâbased surveillance, supplemented with trapping. A total of 304 water samples were filtered from several sampling stations over a 4âyear period. eDNA data (speciesâspecific quantitative realâtime PCR [qPCR]) for the presence of A. astaci, noble and signal crayfish within the water samples were compared to cage mortality and trapping. 3. This is the first study comparing eDNA monitoring and cage surveillance during a natural crayfish plague outbreak. We show that eDNA monitoring corresponds well with the biological status measured in terms of crayfish mortality and trapping results. eDNA analysis also reveals the presence of A. astaci in the water up to 2.5 weeks in advance of the cage method. Estimates of A. astaci and noble crayfish eDNA concentrations increased markedly during mortality and vanished quickly thereafter. eDNA provides a snapshot of the presence, absence or disappearance of crayfish regardless of season, and constitutes a valuable supplement to the trapping method that relies on season and legislation. 4. Synthesis and applications. Simultaneous eDNA monitoring of Aphanomyces astaci (crayfish plague) and relevant native and invasive freshwater crayfish species is wellâsuited for early warning of invasion or infection, risk assessments, habitat evaluation and surveillance regarding pathogen and invasive/native crayfish status. This nonâinvasive, animal welfare friendly method excludes the need for cageâheld susceptible crayfish in disease monitoring. Furthermore, eDNA monitoring is less likely to spread A. astaci than traditional methods. This study resulted in the implementation of eDNA monitoring for Norwegian crayfish plague and crayfish surveillance programmes, and we believe other countries could improve management strategies for freshwater crayfish using a similar approach.publishedVersio
Effects of liraglutide on gallbladder emptying:A randomized, placebo-controlled trial in adults with overweight or obesity
Short-term temporal variation of coastal marine eDNA
Temporal variation in eDNA signals is increasingly explored for understanding community ecology in aquatic habitats. Seasonal changes have been addressed using eDNA sampling, but very little is known regarding short-term temporal variation that spans hours to days. To address this, we filtered marine water samples from a single coastal site in Denmark every hour for 32 h. We used metabarcoding to target both fish and broader eukaryote diversity and evaluated temporal changes in this marine community. Results revealed variation in fish species richness (15â27) and eukaryote class richness (35â64) across the 32 h of sampling, and we further evaluated sampling efforts needed to reach different levels of diversity saturation. Relative read frequency data for both fish and eukaryotes indicated a clear diel change in community composition, with different communities detected during daylight versus dark hours. The abundance signals in our data reflected biological variation rather than stochastic variation, since replicates taken at the same hour were more similar to each other than those taken at different hours. Our compositional results indicated a dynamic community, rather than a static pool of eDNAâeven across a few hours. The fish data showed a daily pattern of relative species abundances, and the uncoupling of fish and broader eukaryote data suggest that variation in eDNA profiles across a single day can provide valuable information reflecting diel changes, at least for highly mobile organism groups. However, our results also point to several pitfalls in current eDNA experimental design, in which samples are taken over large areas without relative time-consistency or short-term replication. Our findings shed new light on short-term variation in coastal eDNA and have wide implications for experimental study design and for incorporating temporality into project conceptualization for future aquatic biodiversity monitoring.publishedVersio
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Terrestrial implications for the maritime geoarchaeological resource: A view from the Lower Palaeolithic
Stone tools and faunal remains have been recovered from the English Channel and the North Sea through trawling, dredging for aggregates, channel clearance, and coring. These finds highlight the potential for a maritime Lower Palaeolithic archaeological resource. It is proposed here that any Lower Palaeolithic artefacts, faunal remains, and sediments deposited in the maritime zone during dry, low-stand phases were once (and may still be) contextually similar to their counterparts in the terrestrial Lower Palaeolithic records of north-western Europe. Given these similarities, can interpretive models and analytical frameworks developed for terrestrial archaeology be profitably applied to an assessment of the potential value of any maritime resource? The terrestrial geoarchaeological resource for the Lower Palaeolithic is dominated by artefacts and ecofacts that have been fluvially reworked. The spatio-temporal resolution of these data varies from entire river valleys and marine isotope stages to river channel gravel bar surfaces and decadal timescales, thus supporting a variety of questions and approaches. However, the structure of the terrestrial resource also highlights two fundamental limitations in current maritime knowledge that can restrict the application of terrestrial approaches to any potential maritime resource: (i) how have the repetitive transgressions and regressions of the Middle and Late Pleistocene modified the terrace landforms and sediments associated with the river systems of the English Channel and southern North Sea basins?; and (ii) do the surviving submerged terrace landforms and fluvial sedimentary deposits support robust geochronological models, as is the case with the classical terrestrial terrace sequences? This paper highlights potential approaches to these questions, and concludes that the fluvial palaeogeography, Pleistocene fossils, and potential Lower Palaeolithic artefacts of the maritime geoarchaeological resource can be profitably investigated in future as derived, low-resolution data sets, facilitating questions of colonisation, occupation, demography, and material culture
MuldfjĂŚlsplovens tidlige historie â Fra yngre romersk jernalder til middelalder
The early history of the mouldboard plough â from the Late Roman Iron Age to the Middle AgesUntil quite recently, the introduction of the mouldboard plough to Denmark was seen as being closely linked to a new efficient Medieval cultivation system, the open-field system, which was considered to be the foundation for dynamic social changes evident in the area from c. AD 1000-1300. The open-field system is often explained in the context of a Medieval agricultural and technological revolution, whereby the mouldboard plough, ridge-and-furrow cultivation and crop rotation were introduced as a kind of package solution. Studies of Danish Medieval written sources suggest that these agrarian changes took place in AD 1000-1200, with use of the mouldboard plough consequently not being thought of as much older.Until the late 1990s, this idea was not contradicted by the significant body of evidence in the Danish archaeological record relating to the mouldboard plough, which in many ways is unique in a European perspective. Subsequently, new archaeological finds of well-preserved furrows made by a mouldboard plough have been discovered which clearly show that this implement was introduced to Denmark about 700-800 years earlier than previously thought, i.e. in the Late Roman Iron Age, c. AD 200-400. This challenges our understanding of the introduction of the mouldboard plough and the history of cultivation systems in Denmark prior to the Middle Ages and the evidence has therefore been subjected to new investigations.Archaeological finds of plough componentsThe archaeological record contains the only known finds of wooden plough components such as the beam, sheath, sole and mouldboard, as well as finds of the coulter, draught chains and shares (fig. 1). These finds can be dated to the period from the Late Viking Age to the Late Middle Ages or Renaissance.The archaeological record, together with pictorial representations on frescoes and seals from Denmark, provides a relatively tangible picture of the plough as basically a quadrilateral construction with the mouldboard attached to the right side. How far back in time this plough construction was used is not known for sure, but it is possible that it was developed by farmers as far back as the Iron Age, possibly being best suited to the asymmetrical function of the plough. It is obviously unlikely that an implement which was used for more than 1500 years remained static and unchanged in every way. As a consequence, the possibility cannot be ruled out that other versions of the mouldboard plough, either simpler or more complex, have existed over time.Ploughing tracesArchaeological investigations have unearthed several minor occurrences of fossil ploughing traces dated to between the Late Iron Age and the Middle Ages. These take the form of ridge-and-furrow systems, turned furrows and furrow strips possibly correlated with the plough (fig. 6).In the light of the traces found at Tating-Haferacker, St. Peter-Ording, Joldelund and Danevirke, it must be assumed that the mouldboard plough was known and used across larger parts of South Schleswig in the Late Roman Iron Age. It may be possible to show that the plough was used even further north Jutland at this time, as the ploughing traces found in Henneby may date from the Late Roman Iron Age rather than the Germanic Iron Age. Notwithstanding the uncertainty regarding Henneby, the traces from Dommerhaven in Ribe and Klinkerne (figs. 2 and 3) show that the plough was known and used in significant parts of western Jutland by the Late Germanic Iron Age at the latest. There are presently no ploughing traces from other parts of Denmark dating from this period, although the furrows found beneath the burial mound Grydehøj on Zealand could have been produced by this plough. Similarly, the traces dated to the Viking Age, found at Hedeby, Fjand, Viborg (fig. 4), Lindholm Høje and LĂśddekĂśpinge, show that the plough must have been known and used across significant parts of Jutland and in Scania before the end of the Viking Age. Early Middle Ages ploughing traces have been found at Filsø and some other locations in Jutland and on Funen, but so far no definite ploughing traces are known from Zealand and Scania. There are only a few localities with ploughing traces dating from the rest of the Middle Ages: Ringkøbing, PuggĂĽrdsgade in Ribe, Amrum and SĂźdfall in the western part of Denmark. The traces found at Ulbjerg Klint are unlikely to be later than the 15th-16th centuries (fig. 5).At first sight, this review of the fossil ploughing traces can be broadly interpreted as showing that the introduction of the plough to Denmark was an extended process, which began in South Schleswig no later than the Late Roman Iron Age and continued into the western parts of Denmark no later than the Germanic Iron Age, and reached the remaining parts of Denmark no later than the Viking Age. The question is, however, whether the review has given a better basis for determining when and how the mouldboard plough became a regular implement in various parts of Denmark. All things considered, the archaeological record only shows where the conditions for preservation have been particularly good for these specific types of finds, and where excavators happen to have found turned furrows when carrying out archaeological investigations. In western Jutland, peaty/boggy soils and sand drift have given good conditions for the preservation of fossil turned furrows, while the same conditions seldom exist in other parts of Denmark. This is emphasised by the fact that the finds of turned furrows dating from the Middle Ages have almost exclusively been found in western Jutland, even though the plough is considered to have been common across most of Denmark at this time. Consequently, the absence of fossil turned furrows cannot be used as evidence of the plough not having been known and used in the area in question. It would therefore be irresponsible to make dogmatic unambiguous statements about regional variations in the introduction of the plough to Denmark.Rye cultivation as an indicator of the use of the ploughThe problem can be addressed indirectly by turning to another source material. Perhaps the the more widespread cultivation of rye may be used as an indicator of the presence of the plough in a given area.Rye, as known from historical times, does not make great demands as to the type of soil, but it does require that the soil has been loosened and is not waterlogged; surface water can also destroy the rye. The mouldboard plough has therefore been considered as a prerequisite for more widespread and systematic cultivation of rye, especially winter rye, on the wet northwest European lowlands. This is because the plough could efficiently loosen the soil and gather it into ridged strips, facilitating field drainage.General developments clearly show that, after a cautious start in Late Roman Iron Age, rye was found increasingly during the Germanic Iron Age and subsequent periods. It would be irresponsible to draw too far-reaching conclusions with respect to relations between rye and the plough. However, if we accept the idea of a connection between the mouldboard plough and the more widespread and systematic cultivation of rye â especially winter rye, then it is tempting to claim that the results of the present review reflect a form of agriculture in which the mouldboard plough was in use across most of Denmark during the Germanic Iron Age.Perspectives on the early introduction of the mouldboard ploughThe mouldboard plough is interesting in both an ecological and a socio-economic context, because it was of major significance for tillage and prompted a reorganisation of field structures that, with time, had a knock-on effect on the structures of settlements and properties.The idea of a technological revolution around AD 1000 acting as a catalyst for dynamic social changes is no longer tenable. The earlier dates now established for the mouldboard plough, the ridged strips and crop rotation clearly show that these significant agricultural prerequisites for a new and effective Medieval system of cultivation, the open-field system, were very well-known in Denmark before this form of agriculture took shape at the beginning of the Early Middle Ages, AD 1000-1200. There is, therefore, no reason to stick to the idea of a technological revolution at this time. The dynamic changes evident in the Middle Ages are, instead, more likely to be a consequence of a general economic expansion, which saw expression for example in an increase in new villages and an associated expansion of the cultivated landscape during the Early Middle Ages.The context in which the earlier introduction of the mouldboard plough should be understood is as yet far from clear. Our knowledge of the plough is still very inadequate and unevenly distributed in time and space, and the archaeological record relating to the cultivation systems of the Late Iron Age, AD 200-1050, is similarly very sporadic.It seems that the introduction of the plough was very likely associated with the significant changes that took place at the transition between the Early and Late Roman Iron Age, c. AD 200, and which characterised society in the subsequent centuries.The earlier introduction of the plough and of ridged- and/or flat-field systems of cultivation must have influenced the organisation of the infield and gradually rendered it impractical to move the settlement around within the resource area, as had been the case since the last centuries BC. Estimates of the percentage of cultivated land at different locations in Denmark show that some settlements must have had cultivated areas corresponding to those of Medieval times as early as the Germanic Iron Age, while other settlements had far smaller areas. This could be one of the reasons that some villages clearly became fixed at their present location already in Late Germanic Iron Age, and not exclusively at the transition between the Viking Age and Middle Ages, c. AD 900-1100, as was previously thought.There are a number of indications that the agrarian society of the Late Iron Age was increasingly able to generate a surplus, which could mobilise an ever more complex social structure: For example, the establishment of large, rich productive sites, especially in the 6th and 7th centuries AD, the founding of the earliest towns, such as Ribe, Aarhus and Hedeby in the 8th and 9th centuries, the emergence of regional kingdoms and the waging of several wars for resources in the period AD 200-600. The earlier introduction of the effective mouldboard plough fits well into this sequence of developments â as one of several significant factors.Lars Agersnap LarsenViborg Museu
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