| 1. |
- Sokolik, Adrian S., et al.
(författare)
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Mercury concentrations in sediment and fish from Nanay River, Peru – a small-scale gold mining area.
- 2006
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Ingår i: Abstracts of Eighth International Conference on Mercury as a Global Pollutant. - 1932078657 ; , s. 574-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Nanay River in the peruvian Amazonian rain forest supports 300 000 inhabitants in the city of Iquitos and surrounding villages with drinking water and fish for consumption. The river has been polluted with mercury, due to the use of the amalgamation method for gold extraction. This has resulted in that local people have got increased levels of mercury, up to 45 mg mercury per litre of blood. The aim of this study was to evaluate the concentrations of mercury in sediment and fish in the Nanay River, Peru, and to study eventual relation between fish mercury concentrations and mercury concentrations in sediment and water parameters such as dissolved organic matter, pH, dissolved oxygen and turbidity. In October 2005, eleven sample points for river water and sediment were established, from the gold mining activities close to Pucaurco westwards (18M 0605010, UTM 9579526) to Pampa Chica eastwards, drinking water source for Iquitos, (18M 0691053, UTM 9585255) in the region Loreto in Peru. Water temperature, conductivity,total dissolved ions, turbidity, dissolved oxygen and pH was measured in the field. Five species of predatory fishes were collected within the study area, where Pintuyacu Riverjoins Nanay River. The samples are currently subject to analyses in Sweden and results will be obtained during the spring. Based on the results, information will be sent to the Regional Government in the region of Loreto about the current state and recommended actions to prevent further contamination.
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| 2. |
- Carpio, A. J., et al.
(författare)
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Angling as a source of non-native freshwater fish : a European review
- 2019
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Ingår i: Biological Invasions. - : Springer Science and Business Media LLC. - 1387-3547 .- 1573-1464. ; 21:11, s. 3233-3248
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Tidskriftsartikel (refereegranskat)abstract
- In a context of the growing concern about the impact of biological invasions, our objective is to review the role of those non-native species that have primarily been introduced for angling purposes in at least one European country. We are particularly interested in: (1) the relative role of sport fish species in the context of non-native species introductions; (2) assessing the relative importance of different fish taxa; (3) identifying similarity patterns in the composition of the angling fish species introduced throughout the continent, and (4) assessing the underlying factors that drive their diversity in Europe. According to our results, 23.6% of the freshwater fish introduced into Europe during the last century were released primarily for angling purposes. The species composition differed among countries, with a higher diversity of introduced angling species in larger countries and in those with a greater GDP per capita, along with a lower latitude. This review stresses that angling was a significant pathway for the introduction of invasive fish species into Europe in the last century. Furthermore, some of the introduced angling species had severe environmental impacts on many European regions. However, introductions of non-native angling species are still occurring. Therefore, existing EU regulations need better enforcement as well as to increase public awareness regarding invasive fish. This will help to preserve biodiversity and improve the sustainability of current angling schemes in increasingly managed European freshwater ecosystems. However, non-native fish could make angling sustainable, although not for biodiversity generally.
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| 3. |
- Carpio, Antonio J., et al.
(författare)
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Effects of wild boar predation on nests of wading birds in various Swedish habitats
- 2016
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Ingår i: European Journal of Wildlife Research. - : Springer Science and Business Media LLC. - 1612-4642 .- 1439-0574. ; 62:4, s. 423-430
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Tidskriftsartikel (refereegranskat)abstract
- The wild boar has, over the past few decades, undergone an expansion in Europe, which may have negatively affected ground-nesting bird populations and particularly those of wading birds. The aim of this study was to evaluate predation on waders’ nests by wild boar in Sweden, where this species has been increasing since its reintroduction. This was done by placing artificial nests in seven different study areas. A comparison was then made of predation rates of the nests placed on control plots (areas in which no wild boar were present but other predators were) and plots containing different abundances of wild boar. Contrary to our expectations, the proportion of nests predated was significantly lower in those areas in which wild boar were present, with a predation rate of 54 %, whereas the predation rate was 87.5 % in the others. The wild boar was identified as the second most important nest predator in the plots in which it was present, accounting for 18 % of the predated nests. The main predator on both types of plots was the red fox, which was responsible for 28 and 38.5 % of the predated nests on plots with/without wild boar, respectively. Interestingly, predation by badgers occurred principally in areas in which the wild boar was absent (34.5 % of the predated nests), whereas only one nest was predated by this predator in areas containing wild boar. It is not, however, possible to state whether predation by badgers was lower because of the presence of wild boar or whether this was owing to the fact that badgers do not select those particular patches because of habitat features.
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| 4. |
- Carpio, Antonio J., et al.
(författare)
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Hunting as a source of alien species : a European review
- 2017
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Ingår i: Biological Invasions. - : Springer Science and Business Media LLC. - 1387-3547 .- 1573-1464. ; 19:4, s. 1197-1211
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Tidskriftsartikel (refereegranskat)abstract
- Hunting activities are responsible for the translocation and restocking of millions of animals throughout Europe, including the introduction of alien species. In a context of the growing use of game translocations and of increasing concern about the impact of biological invasions, our goal is to review the role of alien species introduced primarily for hunting purposes on the European scale. In particular, we explore: (1) the relative importance of game species in the context of alien species introductions; (2) the temporal evolution of the number of species introduced for hunting purposes; (3) the contribution of different taxa; (4) the pattern of introduced game species composition across countries (in terms of similarity), and (5) the underlying human demographic factors driving the diversity of introduced game species per country. According to our results, 24.3% of the mammals and 30.2% of the birds introduced into Europe during the last century were released primarily for hunting purposes, in total, 93 species (63 birds and 36 mammals), the most important taxa being Artiodactyls, Anseriformes and Galliformes. The species composition differed among countries, with a higher diversity of introduced game species in larger countries and in those with a higher human population density and proportion of hunters. This review stresses that hunting was a significant pathway for the introduction of invasive species into Europe in the last century. Since some of the game species introduced have had severe environmental impacts on many European regions, and introductions of non-native game species are still occurring, it is essential to improve regulations and increase public awareness regarding invasive game animals. This will help to preserve biodiversity and improve the sustainability of current hunting schemes in increasingly managed European ecosystems.
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| 5. |
- Carpio, Antonio J., et al.
(författare)
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Wild boar effects on fungal abundance and guilds from sporocarp sampling in a boreal forest ecosystem
- 2022
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Ingår i: Animals. - : MDPI. - 2076-2615. ; 12:19
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Tidskriftsartikel (refereegranskat)abstract
- Native wild boar (Sus scrofa) populations are expanding across Europe. This is cause for concern in some areas where overabundant populations impact natural ecosystems and adjacent agronomic systems. To better manage the potential for impacts, managers require more information about how the species may affect other organisms. For example, information regarding the effect of wild boar on soil fungi for management application is lacking. Soil fungi play a fundamental role in ecosystems, driving essential ecological functions; acting as mycorrhizal symbionts, sustaining plant nutrition and providing defense; as saprotrophs, regulating the organic matter decomposition; or as plant pathogens, regulating plant fitness and survival. During autumn (Sep–Nov) 2018, we investigated the effects of wild boar (presence/absence and rooting intensity) on the abundance (number of individuals) of fungal sporocarps and their functional guilds (symbiotic, saprotrophic and pathogenic). We selected eleven forested sites (400–500 × 150–200 m) in central Sweden; six with and five without the presence of wild boar. Within each forest, we selected one transect (200 m long), and five plots (2 × 2 m each) for sites without wild boar, and ten plots for sites with boars (five within and five outside wild boar disturbances), to determine the relationship between the intensity of rooting and the abundance of sporocarps for three fungal guilds. We found that the presence of wild boar and rooting intensity were associated with the abundance of sporocarps. Interestingly, this relationship varied depending on the fungal guild analyzed, where wild boar rooting had a positive correlation with saprophytic sporocarps and a negative correlation with symbiotic sporocarps. Pathogenic fungi, in turn, were more abundant in undisturbed plots (no rooting) but located in areas with the presence of wild boar. Our results indicate that wild boar activities can potentially regulate the abundance of fungal sporocarps, with different impacts on fungal guilds. Therefore, wild boar can affect many essential ecosystem functions driven by soil fungi in boreal forests, such as positive effects on energy rotation and in creating mineral availability to plants, which could lead to increased diversity of plants in boreal forests.
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| 6. |
- Cichon, M, et al.
(författare)
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Mass-dependent mass loss in breeding birds : getting the null hypothesis right
- 1999
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Ingår i: Oikos. - : JSTOR. - 0030-1299 .- 1600-0706. ; 87:1, s. 191-194
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Tidskriftsartikel (refereegranskat)abstract
- An assumption central to many tests of statistical association between two variables is the null expectation of zero association. Here, we draw attention to the fact that in many published tests of mass-dependent mass loss in breeding birds, this assumption has been violated. We show that a correct null hypothesis can be derived by using resampling methods, and analyse three data sets (two previously published) from passerine birds to illustrate the approach. Our results show, that under a correct null hypothesis, the biological interpretation of the previously published results is reversed-initially heavy birds do actually lose less mass (relative to their weight) than the initially light birds.
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| 7. |
- Djerdali, Sofia, et al.
(författare)
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Food supply and external cues limit the clutch size and hatchability in the White Stork Ciconia ciconia
- 2008
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Ingår i: Acta Ornithologica. - 0001-6454 .- 1734-8471. ; 43:2, s. 145-150
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Tidskriftsartikel (refereegranskat)abstract
- Clutch size is an important life history trait and factors such as nest predation and food availability can both be of crucial importance for its variation in nature. The aim of the present study was to evaluate the effects of extra food on clutch size, laying date and hatching success in the White stork Ciconia ciconia. Three different colonies of White stork were studied over a three-year period where there was difference in both food availability and precipitation. This study demonstrated that an extra food supply during the pre-laying period had a positive effect on clutch size - nests with extra food had a larger clutch size. There was also an advance in laying date and a higher hatching success in nests with access to extra food. In addition to food supply, clutch size was independently affected by rainfall, which suggests that parents additionally also were sensitive to other external cues than to the extra food. Furthermore, this study also suggests that an extra food during the incubation period could probably help the parents to solve the conflict between incubation behaviour and minimizing the time off the nest, i.e. increasing nest attentiveness in nests with extra food.
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| 8. |
- Guerrero-Casado, José, et al.
(författare)
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Assessment of the suitability of latrine counts as an indirect method by which to estimate the abundance of European rabbit populations at high and low abundance
- 2020
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Ingår i: European Journal of Wildlife Research. - : Springer Science and Business Media LLC. - 1612-4642 .- 1439-0574. ; 66:1
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring European rabbit (Oryctolagus cuniculus) populations using suitable methods is crucial, especially in those areas in which endangered predators remain and rabbits occur at low densities. We first counted the number of rabbits, the number of scattered pellets, and the number of latrines counted within 16 plots established in areas of low rabbit density, showing that the number of rabbits counted inside the plots was more closely correlated with the number of pellets counted than with the number of latrines. In addition, no latrines were found in 8 plots. In 53 walking transects, the number of pellets m−2 and the number of latrines km−1 had a positive relationship, but no significant correlation was obtained between the two methods when only the transects with a low rabbit abundance were selected. These results suggest that although counting latrines can be useful to compare areas with different abundances, it may underestimate rabbit abundance at low abundances where counting scattered pellets is, therefore, the most accurate alternative. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
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| 9. |
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| 10. |
- Hillström, Lars
(författare)
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Estimation of state and identification of complex modulus based on measurements om a bar traversed by waves
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Estimation of state and identification of complex modulus based on measurements on non-uniform rods and beams have been studied theoretically and experimentally. Two principal cases were studied. In the first case, the material properties are fully known and the state at a section is to be estimated. In the second case, the complex modulus is to be identified (and optionally the state is to be estimated). Nothing needs to be known about supports, structures and loads outside the rod and beam segments under consideration. In particular, analytical expressions of the standard deviation of the non-parametric complex modulus were derived for a uniform rod.Experimental tests were performed with rods of polymethyl methacrylate (PMMA) and polypropylene (PP) and with beams of aluminium, PMMA and PP. Both parametric and non-parametric complex moduli were determined in the frequency domain. For a uniform rod, parametric complex moduli were determined also in the time domain.It was found that the identification of the non-parametric complex modulus and the estimation of state may be inaccurate at certain discrete frequencies. It was shown how such inaccuracies can be avoided in the frequency range of interest by use of more than the minimum number of measurement sections and a non-uniform distribution of them. If a parametric complex modulus is used, the results should be compared with those for a non-parametric modulus. The parametric complex moduli determined in the time domain deviated more than expected from the complex moduli determined in the frequency domain. The reasons for these deviations are not fully understood.
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| 11. |
- Hillström, Lars, 1956-, et al.
(författare)
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Evolution of antlers in the moose Alces alces : a comparison of two different populations in Sweden
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish moose population has during the last 60 years been going through rather drastic changes in numbers. Recently there also seemed to have been a shift towards males with less and less developed antlers, which is an important problem for the moose population breeding. The aim with the present study was to study how antler size in the moose is related to age, body mass and population density. Information on the antler and body mass characters was obtained from 425 males that were shot during the annual moose hunting in October between the years 1999-2006. Age and body mass were the variables that explained most of the variation in antler size in this study. A residual of antler points over age, demonstrated a positive correlation between residuals and carcass, such that males with larger antlers for their age, was on average heavier than other males. There was also a significant negative correlation between population density and carcass. The high mortality rate of older males have lead to that few males reach an age where the horns are fully developed and the age distribution has moved to younger ages. As a consequence of this fact the males start to reproduce at younger ages. As the rutting behaviour is a very energy demanding activity, the younger male’s body growth will be constrained and there will be a large cost to come in rutting stage early. As the percentage of males and male age is having an impact on the reproduction of the population, this is an important problem which should be considered in order to give the right prerequisites for a more productive population of moose with big males that have well developed horns.
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| 12. |
- Hillström, Lars, et al.
(författare)
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Is asynchronous hatching adaptive in herring gulls ( Larus argentatus )?
- 2000
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 47:5, s. 304-311
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Tidskriftsartikel (refereegranskat)abstract
- Hatching asynchrony commonly induces a size hierarchy among siblings and the resultant competition for food between siblings can often lead to starvation of the smallest chicks within a brood. We created herring gull (Larus argentatus) broods with varying degrees of hatching synchrony by manipulating the timing of incubation while maintaining the originally laid eggs. The degree of hatching asynchrony affected sibling size hierarchy at the time of hatching of the last-hatched ”c-chick.” In unmanipulated broods, there was no disadvantage of being a c-chick. However, when asynchrony was experimentally increased, we found reduced survival of the c-chick only in the exaggerated asynchronous experimental group. The effects were observable only during the first 10 days of chick life. We recorded no cases of the chicks dying of starvation. Furthermore, behavioral observations indicated that there was no sibling competition, and no selective feeding of larger sibs in the study colony. We propose that the observed lower survival rates of c-chicks in exaggerated asynchronous broods resulted from their lesser motor abilities, affecting their chances of escaping predators. Fledging success for the whole colony was generally high and almost half of all pairs fledged all three chicks, which is indicative of a good feeding environment. We argue that normal hatching asynchrony is a favorable solution in a good feeding environment, but that increased asynchrony reduces breeding success. We do not view asynchrony in the herring gull as an adaptation for brood reduction and propose instead that it may come about because there has been selection for incubation to start before clutch completion.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Hillström, Lars, 1956-, et al.
(författare)
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The evolution of reversed sexual dimorphism in birds : a comparative study in charadriiformes
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Reversed size dimorphism is common in birds of prey, owls and in waders. Not much attention has been paid to the evolution of morphological characters such as wing morphology and variables related to flight agility. The aim of this study was to investigate if the morphological variables in shorebirds, related to flight performance, such as wing length, wing area, wing loading, and factors such as aspect ratio, are related to the display-flights performed by these different species of shorebirds. Data on morphological variables, e.g. body mass, wing length, wing area etc. was collected at the British Museum of Natural History, London, UK.Data on behavioral variables, e.g. duration of a display flight or height of display flight was extracted from the published literature. There was a significant difference in wing length dimorphism (t = 2.51, p= 0.0402), when comparing between species within the same genus that had higher versus lower level of flight performance. There was also a significant difference in wing area dimorphism (t = 2.84, p= 0.025), for higher versus lower level of flight performance. However, there was no such difference for weight dimorphism, nor for tarsus dimorphism, or for wing loading or aspect ratio, when comparing between species for higher versus lower level of flight performance. Further analyses will be presented and a suggestive explanation for the evolution of reversed sexual dimorphism will be discussed at the congress. The hypotheses for increased food- or incubation efficiency is with several arguments irrelevant to shorebirds (which will be discussed).
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| 18. |
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| 19. |
- Lundin, Mikael, et al.
(författare)
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Selection efficiency of encircling grids in a herring pontoon trap
- 2011
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Ingår i: Fisheries Research. - : Elsevier BV. - 0165-7836 .- 1872-6763. ; 111:1-2, s. 127-130
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Tidskriftsartikel (refereegranskat)abstract
- High bycatches of undersized herring constitute a major problem in the Baltic Sea herring trap fishery. In an attempt to reduce these bycatches, this field study evaluates the efficiency of rigid selection grids encircling a herring pontoon trap. The results show that 54-72% of the undersized herring were removed from the catch. The introduction of such grids would therefore represent a significant step towards a more efficient and sustainable herring fishery in the Baltic Sea. © 2011 Elsevier B.V.
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| 20. |
- Mahata, Kaushik, et al.
(författare)
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On the use of flexural wave propagation experiments for identification of complex modulus
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, we investigate the estimation of the complex modulus of a viscoelastic material from flexural wave experiments. A bar specimen of uniform cross-section is subjected to lateral impact by a steel ball giving rise to flexural waves traveling along the bar. The strains due to wave propagation are registered as functions of time using strain gauges at different sections. The measured strains are transformed in to the frequency domain. A non-parametric estimation of the complex modulus is carried out for each frequency. An analysis of the quality of the non-parametric estimate is carried out. The validity of the theoretical results are confirmed by numerical studies and experimental tests.
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| 21. |
- Mossberg, Magnus, et al.
(författare)
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Parametric identification of viscoelastic materials from time and frequency domain data
- 2001
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Ingår i: Inverse Problems in Engineering. - : Informa UK Limited. - 1068-2767 .- 1029-0281. ; 9:6, s. 645-670
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Tidskriftsartikel (refereegranskat)abstract
- In this paper a parametric model of the elasticity modulus of a viscoelastic material (polypropylene) is determined by measured strains from wave propagation experiments. The identification of the model parameters is carried out both in the time and in the frequency domain. The advantages and limitations of either approach is discussed. Our main result is that a good representation of the elasticity modulus can be obtained by a general standard linear solid with three elements or seven free parameters. The model is valid over the same frequency range as that of the data, which in the present case extends from 100 Hz to 10 kHz. Such a model makes it possible to perform direct time simulations by time-stepping algorithms.
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| 22. |
- Mousavi, Saed, et al.
(författare)
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Identification of complex shear modulus from measured shear strains on a circular disc subjected to transient torsion at its centre
- 2008
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X .- 1095-8568. ; 313:3-5, s. 567-580
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Tidskriftsartikel (refereegranskat)abstract
- A method for identification of complex shear modulus from measured shear strains on a circular disc subjected to a transient torque at its centre has been established. It is based on the evolution of an outgoing shear wave between two radial positions at which the associated shear strains are measured. The two-dimensional shear wave solutions used are exact in the sense of three-dimensional theory. Therefore, in principle, there is no frequency beyond which they are not valid. The method requires a minimum disc size, which is related to the duration of the load. The non-parametric results become inaccurate at frequencies near zero and at certain problematic frequencies where the excitation of the disc is weak or non-existent. These frequencies may be moved outside the frequency range of interest by sufficiently decreasing the duration of the load. If there are problematic frequencies within this range, the results of parametric identification become more accurate than those of non-parametric identification. Parametric results from experimental tests with loads having different amplitudes and durations agree well with each other in accord with the assumed linearity of the tested polypropylene material.
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| 23. |
- Sanchez Tortosa, Francisco, et al.
(författare)
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Effect of food abundance on laying date and clutch size in the White Stork Ciconia ciconia
- 2003
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Ingår i: Bird Study. - 0006-3657 .- 1944-6705. ; 50, s. 112-115
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Tidskriftsartikel (refereegranskat)abstract
- Capsule- Food independently affects both laying date and clutch size, suggesting that seasonal decline in clutch size is related to a decrease in food availability. Aim - To test the effect of food abundance on laying date and clutch size of the White Stork and identify the cause of seasonal decline in the number of eggs laid. Methods - During 1991 and 1996 we recorded clutch size and laying date of pairs breeding next to rubbish dumps (food abundant and constant throughout the breeding season) and birds breeding far from rubbish dumps (using natural food sources). Results - In 1991 there was no difference in mean laying date between pairs nesting at rubbish dumps and control pairs. Clutch size was significantly larger at rubbish dump nests. In contrast, mean laying date was earlier in control pairs in 1996 and there was no significant differences in clutch sizes, even when controlling for laying date effect. Conclusion - The results support the hypothesis that food availability independently affects both laying date and clutch size. The seasonal decline in clutch size close to rubbish dumps was negligible (1991) or much smaller than in the control zone (1996) suggesting that a progressive deterioration of natural food sources is the most probable reason for a decline in clutch size as the season advances.
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| 24. |
- Svanberg, Fredrik, et al.
(författare)
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Lead isotopes and lead shot ingestion in the globally threatened marbled teal (Marmaronetta angustirostris) and white-headed duck (Oxyura leucocephala)
- 2006
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 370:2-3, s. 416-424
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Tidskriftsartikel (refereegranskat)abstract
- Lead isotope ratios ((206)Pb/(207)Pb and (208)Pb/(207)Pb) and concentrations in the livers and bones of marbled teal and white-headed duck found dead or moribund were determined in order to establish the main lead source in these waterfowl species. Lead concentrations in bone (dry weight) and liver (wet weight) were found to be very high in many of the white-headed ducks (bone: geometric mean=88.9 ppm, maximum=419 ppm; liver: geometric mean=16.8 ppm, maximum=57.0 ppm). Some of the marbled teal had high lead levels in the bones but liver lead levels were all low (bone: geometric mean=6.13 ppm, maximum=112 ppm; liver: geometric mean=0.581 ppm, maximum=4.77 ppm). Ingested lead shot were found in 71% of the white-headed duck and 20% of the marbled teal. The (206)Pb/(207)Pb ratio in livers and bones of white-headed ducks and marbled teals showed no significant differences compared to the ratios obtained from lead shot. The (206)Pb/(207)Pb ratio in bones of marbled teal ducklings with the highest lead concentrations tended to resemble the ratios of lead shot, which supports our hypothesis that the lead was derived from the hens. We also found that the lead ratios of lead shot and lead ratios described for soils in the area overlapped, but also that the isotopic ratio (206)Pb/(207)Pb in lead shot used in Spain has a narrow range compared with those used in North America. The principal source of lead in many of these birds was, however, most likely lead shot, as supported by the similar isotopic ratios, high lead concentrations in tissues and evidence of ingested shot.
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| 25. |
- Taggart, Mark A., et al.
(författare)
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Metal levels in the bones and livers of globally threatened marbled teal and white-headed duck from El Hondo, Spain
- 2009
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Ingår i: Ecotoxicology and Environmental Safety. - Amsterdam : Elsevier BV. - 0147-6513 .- 1090-2414. ; 72:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- El Hondo is a key area for marbled teal and white-headed duck. We present Pb, Cu, Zn, Se, and As data for bone and liver in birds found dead between 1996 and 2001. Several metals were higher in adult white-headed ducks than in marbled teal. They were higher in female than in male white-headed ducks, and did not differ with sex in marbled teal, but did by age. Lead in liver of adults was influenced by Pb shot ingestion, which was detected in 21% of marbled teal and in 71% of white-headed duck. No marbled teal had liver levels indicative of Pb poisoning, while 86% of white-headed ducks did. Selenium, Zn, and Cu were elevated in 13%, 7%, and 39% of birds, respectively. Whilst Pb shot poses the greatest threat to these species, further work should assess exposure via plants, invertebrates, water, and sediments for other metals, and investigate possible sub-lethal effects.
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| 26. |
- Åhman, Fredrik, et al.
(författare)
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Using a Game Theoretical Approach for Experimental Simulation of Brood Reduction : Conflict and Co-Operation, Effect on Brood Size with Limited Resources
- 2005
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Ingår i: Proceedings of the Seventh International Conference on Enterprise Information Systems. - 9728865198 ; , s. 220-225
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Konferensbidrag (populärvet., debatt m.m.)abstract
- The evolution of parental care includes typical caring behaviour, such as protecting or feeding offspring. Sibling rivalry is anthropogenic viewed as conflicting behaviour, and can ultimately lead to brood reduction. In this study we have used object oriented programming to simulate different scenarios in this sibling rivalry conflict. A number of hypotheses have been proposed to explain the complex interactions occurring during brood reduction, but few simulation models successfully combines it with a hypothesis necessary to describe an ESS. In our solution we present a simple experimental simulation for brood reduction, where each sibling acts as an autonomous agent that has the ability to initiate actions for cooperation and competition against other siblings. Agents have a limited set of actions that can be activated during the onset of some specific environmental conditions, such as prey density, different climate variables etc. Parameters for food distribution are determined on a basis of a former known theory for maximizing inclusive fitness. In the computer simulations we have studied effects on sizes of siblings and fitness measures with varying degree of hatching patterns and prey density for siblings within the artificial brood. Results from the experimental simulations demonstrate interesting similarities with brood reduction in a real world setting, such as in raptorial birds that practice facultative siblicidal behaviour. Agents within the artificial brood respond with stronger conflicting behaviour whenever resources are limited and simulating increased hatching asynchrony lead to a lower survival rate (because of increased size hierarchy) of siblings within the simulated brood.
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