144 research outputs found

    Erosion of the Geodetic Hills Fossil Forest, Axel Heiberg Island, Northwest Territories

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    Studies on the erosion of the Geodetic Hills Fossil Forest on the east side of Axel Heiberg Island, Northwest Territories have indicated that erosion by wind averaged a depth of 1.3 cm for the period 1988 to 1992. The fossil wood and leaf litter tend to dry on exposure, resulting in shrinkage and fragmentation - sometimes in less than a year. Frost, especially at the boundaries of polygons, repeatedly compresses and disrupts the fossil-bearing strata. Erosion by water takes place as rills on the sides of hills. Solifluction displaces surface sediment on the sides of the hills in the range of 6 to 45 cm per year. In the last few years the physical disruption of stumps, tree trunks and forest mat has been caused mainly by people: by walking on the site, by excavating it, and by flying over and landing helicopters on it. Natural processes - including wind, freezing and thawing, rainfall, and wandering animals - also cause damage. In 1992, 62 stumps recorded in the 1988 survey (ca. 10% of the total) could not be relocated. There are problems in accounting for this discrepancy, because only a few stumps are known to have been removed by investigators for study, and it seems unlikely (although it is possible) that others may have been removed by unknown visitors. Some of the "missing" stumps may still be present, but disturbance in the surface sediment caused by scientific excavation or wind-driven accretion have made them untraceable. Vestigial stumps may simply have weathered away in the period between surveys, and finally some of the losses may be accounted for by errors in the initial surveying. Since preservation is important both for long-term scientific interpretation and for public access, the site should be better managed. The authors advocate that the site be managed by the Canadian Parks Service as an annex to Ellesmere Island National Park Reserve.Key words: fossil forest, Axel Heiberg Island, wood, leaf litter, erosion, preservationDes études sur l'érosion de la forêt fossile des collines géodésiques du côté est de l'île Axel Heiberg dans les Territoires du Nord-Ouest ont révélé que l'érosion éolienne était d'en moyenne 1,3 cm au cours de la période allant de 1988 à 1992. Le bois et la couche de feuilles mortes fossiles ont tendance à sécher s'ils sont exposés aux éléments, ce qui aboutit au retrait et à la fragmentation - parfois en moins d'un an. Le gel, en particulier aux limites des polygones, comprime et disloque les strates fossilifères de façon répétée. L'érosion hydrique se produit sous forme de rigoles sur les pentes des collines. La solifluxion déloge les sédiments de surface sur les pentes des collines à une vitesse de 6 à 45 cm par an. Au cours des dernières années, la perturbation physique des souches, des troncs d'arbre et du tapis forestier a été causée principalement par les humains: piétinement et excavation du site, survols et atterrissages des hélicoptères. Les processus naturels - y compris le vent, le gel et dégel, les précipitations et le déplacement des animaux - causent également des dommages. En 1992, 62 souches consignées dans le relevé de 1988 (environ 10 p. cent du total) n'ont pu être retrouvées. On a de la difficulté à expliquer cet écart, car on sait que quelques souches seulement ont été enlevées par les chercheurs pour effectuer leurs travaux, et il semble peu probable (bien que ce soit possible) que d'autres souches aient été enlevées par des visiteurs inconnus. Il se peut que certaines des souches «absentes» soient toujours présentes, mais la perturbation des sédiments de surface causée par des excavations scientifiques ou l'accrétion éolienne fait qu'elles sont impossibles à retracer. Des souches résiduelles ont peut-être tout simplement été détruites par les éléments durant les périodes entre les relevés, et finalement, certaines des pertes peuvent être expliquées par des erreurs dans le relevé initial. Vu que la conservation est importante à la fois pour l'interprétation scientifique à long terme et pour l'accès du public, le site devrait être mieux géré. Les auteurs recommandent que la gestion en soit remise au Service canadien des parcs, en tant qu'annexe à la réserve de parc national de l'île-d'Ellesmere.Mots clés: forêt fossile, île Axel Heiberg, bois, couche de feuilles mortes, érosion, conservatio

    Exploring pig trade patterns to inform the design of risk-based disease surveillance and control strategies

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    An understanding of the patterns of animal contact networks provides essential information for the design of risk-based animal disease surveillance and control strategies. This study characterises pig movements throughout England and Wales between 2009 and 2013 with a view to characterising spatial and temporal patterns, network topology and trade communities. Data were extracted from the Animal and Plant Health Agency (APHA)’s RADAR (Rapid Analysis and Detection of Animal-related Risks) database, and analysed using descriptive and network approaches. A total of 61,937,855 pigs were moved through 872,493 movements of batches in England and Wales during the 5-year study period. Results show that the network exhibited scale-free and small-world topologies, indicating the potential for diseases to quickly spread within the pig industry. The findings also provide suggestions for how risk-based surveillance strategies could be optimised in the country by taking account of highly connected holdings, geographical regions and time periods with the greatest number of movements and pigs moved, as these are likely to be at higher risk for disease introduction. This study is also the first attempt to identify trade communities in the country, information which could be used to facilitate the pig trade and maintain disease-free status across the country in the event of an outbreak

    The differential contribution of maternal and paternal values to social competence of preschoolers

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    Multivariate analyses were conducted to clarify the nature of the influences of parental values on social behaviours of kindergarteners in the context of sociodemographic variables and sex of participants. This study included 217 mothers and 172 fathers from the same families, who completed a socio-demographic questionnaire and a new Q-sort that assesses parental values on Individualism (IND)/Collectivism (COL) and Horizontal (HOR)/Vertical (VER) continuums.To test the hypothesis of an association between parental values and children’s behaviours, teachers also provided information about each child’s social competence, anger-aggression, and anxiety-withdrawal in kindergarten using the Social Competence and Behavior Scale. Parents shared a greater proportion of IND/COL than VER values and mothers were more likely to emphasise IND and COL values than fathers. Mothers within IND and COL groups had more socially competent kindergartners as reported by teachers. Considering the mixed results found in the literature regarding sex differences in parenting and behaviours of children, the present results suggested that examining more closely the system of parental values might offer valuable avenues for uture research on early childhood socialisation

    Dynamical Patterns of Cattle Trade Movements

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    Despite their importance for the spread of zoonotic diseases, our understanding of the dynamical aspects characterizing the movements of farmed animal populations remains limited as these systems are traditionally studied as static objects and through simplified approximations. By leveraging on the network science approach, here we are able for the first time to fully analyze the longitudinal dataset of Italian cattle movements that reports the mobility of individual animals among farms on a daily basis. The complexity and inter-relations between topology, function and dynamical nature of the system are characterized at different spatial and time resolutions, in order to uncover patterns and vulnerabilities fundamental for the definition of targeted prevention and control measures for zoonotic diseases. Results show how the stationarity of statistical distributions coexists with a strong and non-trivial evolutionary dynamics at the node and link levels, on all timescales. Traditional static views of the displacement network hide important patterns of structural changes affecting nodes' centrality and farms' spreading potential, thus limiting the efficiency of interventions based on partial longitudinal information. By fully taking into account the longitudinal dimension, we propose a novel definition of dynamical motifs that is able to uncover the presence of a temporal arrow describing the evolution of the system and the causality patterns of its displacements, shedding light on mechanisms that may play a crucial role in the definition of preventive actions

    Dynamical Patterns of Cattle Trade Movements

    Get PDF
    Despite their importance for the spread of zoonotic diseases, our understanding of the dynamical aspects characterizing the movements of farmed animal populations remains limited as these systems are traditionally studied as static objects and through simplified approximations. By leveraging on the network science approach, here we are able for the first time to fully analyze the longitudinal dataset of Italian cattle movements that reports the mobility of individual animals among farms on a daily basis. The complexity and inter-relations between topology, function and dynamical nature of the system are characterized at different spatial and time resolutions, in order to uncover patterns and vulnerabilities fundamental for the definition of targeted prevention and control measures for zoonotic diseases. Results show how the stationarity of statistical distributions coexists with a strong and non-trivial evolutionary dynamics at the node and link levels, on all timescales. Traditional static views of the displacement network hide important patterns of structural changes affecting nodes' centrality and farms' spreading potential, thus limiting the efficiency of interventions based on partial longitudinal information. By fully taking into account the longitudinal dimension, we propose a novel definition of dynamical motifs that is able to uncover the presence of a temporal arrow describing the evolution of the system and the causality patterns of its displacements, shedding light on mechanisms that may play a crucial role in the definition of preventive actions

    Rare copy number variants contribute to congenital left-sided heart disease

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    Left-sided congenital heart disease (CHD) encompasses a spectrum of malformations that range from bicuspid aortic valve to hypoplastic left heart syndrome. It contributes significantly to infant mortality and has serious implications in adult cardiology. Although left-sided CHD is known to be highly heritable, the underlying genetic determinants are largely unidentified. In this study, we sought to determine the impact of structural genomic variation on left-sided CHD and compared multiplex families (464 individuals with 174 affecteds (37.5%) in 59 multiplex families and 8 trios) to 1,582 well-phenotyped controls. 73 unique inherited or de novo CNVs in 54 individuals were identified in the left-sided CHD cohort. After stringent filtering, our gene inventory reveals 25 new candidates for LS-CHD pathogenesis, such as SMC1A, MFAP4, and CTHRC1, and overlaps with several known syndromic loci. Conservative estimation examining the overlap of the prioritized gene content with CNVs present only in affected individuals in our cohort implies a strong effect for unique CNVs in at least 10% of left-sided CHD cases. Enrichment testing of gene content in all identified CNVs showed a significant association with angiogenesis. In this first family-based CNV study of left-sided CHD, we found that both co-segregating and de novo events associate with disease in a complex fashion at structural genomic level. Often viewed as an anatomically circumscript disease, a subset of left-sided CHD may in fact reflect more general genetic perturbations of angiogenesis and/or vascular biology

    A mixed methods inquiry: How dairy farmers perceive the value(s) of their involvement in an intensive dairy herd health management program

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    <p>Abstract</p> <p>Background</p> <p>Research has been scarce when it comes to the motivational and behavioral sides of farmers' expectations related to dairy herd health management programs. The objectives of this study were to explore farmers' expectations related to participation in a health management program by: 1) identifying important ambitions, goals and subjective well-being among farmers, 2) submitting those data to a quantitative analysis thereby characterizing perspective(s) of value added by health management programs among farmers; and 3) to characterize perceptions of farmers' goals among veterinarians.</p> <p>Methods</p> <p>The subject was initially explored by means of literature, interviews and discussions with farmers, herd health management consultants and researchers to provide an understanding (a concourse) of the research entity. The concourse was then broken down into 46 statements. Sixteen Danish dairy farmers and 18 veterinarians associated with one large nationwide veterinary practice were asked to rank the 46 statements that defined the concourse. Next, a principal component analysis was applied to identify correlated statements and thus families of perspectives between respondents. Q-methodology was utilized to represent each of the statements by one row and each respondent by one column in the matrix. A subset of the farmers participated in a series of semi-structured interviews to face validate the concourse and to discuss subjects like animal welfare, veterinarians' competences as experienced by the farmers and time constraints in the farmers' everyday life.</p> <p>Results</p> <p>Farmers' views could be described by four families of perspectives: Teamwork, Animal welfare, Knowledge dissemination, and Production. Veterinarians believed that farmers' primary focus was on production and profit, however, farmers' valued teamwork and animal welfare more.</p> <p>Conclusion</p> <p>The veterinarians in this study appear to focus too much on financial performance and increased production when compared to most of the participating farmers' expectations. On the other hand veterinarians did not focus enough on the major products, which farmers really wanted to buy, i.e. teamwork and animal welfare. Consequently, disciplines like sociology, economics and marketing may offer new methodological approaches to veterinarians as these disciplines have understood that accounting for individual differences is central to motivate change, i.e. 'know thy customer'.</p

    Morphological and Physiological Responses to Drought Stress of European Provenances of Scots Pine

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    Increased frequency and intensity of drought episodes as a consequence of current and predicted climatic changes require an understanding of the intra-specific variability in structural and physiological characteristics of forest trees. Adaptive plasticity and genotypic variability are considered two of the main processes by which trees can either be selected or can acclimate to changing conditions. We tested for the relative importance of genotypic variability, phenotypic plasticity and their interaction by comparing the growth and physiological performance of 15 provenances of Scots pine (Pinus sylvestris L.), under two contrasting irrigation regimes. Selected provenances representing the distribution range of the species in Anatolia, Turkey, were contrasted with seed sources spanning the range from Spain to the UK, in Europe. We found a strong latitudinal differentiation among the 15 provenances for survival after drought, largely the result of the higher mortality of some western and central European provenances. Differentiation in diameter and height growth was also clear with the worst provenance coming from Western Europe (UK). Among the Turkish provenances, the more extreme southern high-elevation populations showed greater survival and lower growth rates overall. Differences in growth and survival were related to differences in photosynthetic pigment and nutrient contents and in the photosynthetic efficiency of photosystem II. Plasticity was strongest for growth characters and pigment contents.WoSScopu
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