125 research outputs found

    The High Arctic Wolf in the Jones Sound Region of the Canadian High Arctic

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    The high arctic wolf Canis lupus arctos, a white, medium-sized subspecies of the arctic wolf, and a considerable carnivore, ranges over the Queen Elizabeth Islands of the Canadian Arctic Archipelago. … With the object of adding to the meagre literature on the high arctic wolf, I present in this paper the results of observations I made on it over a total period of 425 days spent in the field in the Jones Sound region, collecting information on the local wildlife and Inuit. … Little is actually known about the wolf's predatory behaviour in the eastern High Arctic, and much of what is attributed to the high arctic wolf is merely hearsay or speculation. For example, in the Jones Sound region muskox carcasses which bear signs of attention from wolves are usually referred to as wolf-kills. It is possible that some of these carcasses have simply been scavenged by wolves. … Over the years, some of the residents of Grise Fiord have attributed the decline of Peary's caribou Rangifer tarandus pearyi in the region to the predatory habits of wolves, in spite of the absence of any proof that they have a controlling effect upon the size of caribou populations. It appears in actual fact that man has been blaming his competitor, the wolf, for the problems he himself has created. … From data based on reports of members of the Grise Fiord Detachment of the R.C.M.P. I have been able to derive the following average numbers of wolves taken: 1956-57 to 1962-63: 1.7; 1963-64 to 1967-68: 4.4; 1968-69 to 1970-71: 9.6. The sharp increase from 1.7 to 4.4 was a result of the reintroduction in 1964 of bounty payments in the Northwest Territories for the capture of wolves. A hunter receives 40foreachanimalcaptured,aswellasthepeltwhichhasavaluerangingbetween40 for each animal captured, as well as the pelt which has a value ranging between 10 and $150. Some pelts are used locally for the trimming of parkas, for which they are however considered inferior to the pelts of dogs or imported wolverine. Most wolves taken up to 1968 were either poisoned, accidentally caught in fox traps, or shot as they approached hunters or their dogs out of curiosity. Since the coming into general use of snowmobiles in the area, however, hunters have usually followed any fresh wolf track in the hope of catching up with one of the animals. The fact that the average number caught over the three years ending in 1971 was as high as 9.6 per year was therefore the result of overhunting by snowmobile, and not of an increase in numbers of the animals. The overhunting which took place over the years 1968-71 is the presumable explanation of the fact that not one wolf was taken during the years 1971-72. … Wolf carcasses are not eaten either by Inuit or their dogs

    Fractional Hamilton formalism within Caputo's derivative

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    In this paper we develop a fractional Hamiltonian formulation for dynamic systems defined in terms of fractional Caputo derivatives. Expressions for fractional canonical momenta and fractional canonical Hamiltonian are given, and a set of fractional Hamiltonian equations are obtained. Using an example, it is shown that the canonical fractional Hamiltonian and the fractional Euler-Lagrange formulations lead to the same set of equations.Comment: 8 page

    Fractional Euler-Lagrange differential equations via Caputo derivatives

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    We review some recent results of the fractional variational calculus. Necessary optimality conditions of Euler-Lagrange type for functionals with a Lagrangian containing left and right Caputo derivatives are given. Several problems are considered: with fixed or free boundary conditions, and in presence of integral constraints that also depend on Caputo derivatives.Comment: This is a preprint of a paper whose final and definite form will appear as Chapter 9 of the book Fractional Dynamics and Control, D. Baleanu et al. (eds.), Springer New York, 2012, DOI:10.1007/978-1-4614-0457-6_9, in pres

    Fractional variational calculus of variable order

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    We study the fundamental problem of the calculus of variations with variable order fractional operators. Fractional integrals are considered in the sense of Riemann-Liouville while derivatives are of Caputo type.Comment: Submitted 26-Sept-2011; accepted 18-Oct-2011; withdrawn by the authors 21-Dec-2011; resubmitted 27-Dec-2011; revised 20-March-2012; accepted 13-April-2012; to 'Advances in Harmonic Analysis and Operator Theory', The Stefan Samko Anniversary Volume (Eds: A. Almeida, L. Castro, F.-O. Speck), Operator Theory: Advances and Applications, Birkh\"auser Verlag (http://www.springer.com/series/4850

    Exploring traditional aus-type rice for metabolites conferring drought tolerance

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    Background: Traditional varieties and landraces belonging to the aus-type group of rice (Oryza sativa L.) are known to be highly tolerant to environmental stresses, such as drought and heat, and are therefore recognized as a valuable genetic resource for crop improvement. Using two aus-type (Dular, N22) and two drought intolerant irrigated varieties (IR64, IR74) an untargeted metabolomics analysis was conducted to identify drought-responsive metabolites associated with tolerance. Results: The superior drought tolerance of Dular and N22 compared with the irrigated varieties was confirmed by phenotyping plants grown to maturity after imposing severe drought stress in a dry-down treatment. Dular and N22 did not show a significant reduction in grain yield compared to well-watered control plants, whereas the intolerant varieties showed a significant reduction in both, total spikelet number and grain yield. The metabolomics analysis was conducted with shoot and root samples of plants at the tillering stage at the end of the dry-down treatment. The data revealed an overall higher accumulation of N-rich metabolites (amino acids and nucleotide-related metabolites allantoin and uridine) in shoots of the tolerant varieties. In roots, the aus-type varieties were characterised by a higher reduction of metabolites representative of glycolysis and the TCA cycle, such as malate, glyceric acid and glyceric acid-3-phosphate. On the other hand, the oligosaccharide raffinose showed a higher fold increase in both, shoots and roots of the sensitive genotypes. The data further showed that, for certain drought-responsive metabolites, differences between the contrasting rice varieties were already evident under well-watered control conditions. Conclusions: The drought tolerance-related metabolites identified in the aus-type varieties provide a valuable set of protective compounds and an entry point for assessing genetic diversity in the underlying pathways for developing drought tolerant rice and other crops.Alberto Casartelli, David Riewe, Hans Michael Hubberten, Thomas Altmann, Rainer Hoefgen and Sigrid Heu

    Thermal Imaging and Physiological Analysis of Cold-Climate Caribou-Skin Clothing

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    Protective clothing is essential for human existence in the Arctic, and caribou-skin clothing has played a pivotal role for millennia. Although people with northern experience often extol caribou-skin clothing, few scientific studies have investigated its properties. We used infrared thermal imaging in a pilot study to compare authentic caribou-skin clothing sewn by traditional Inuit seamstresses with two other types of cold-weather clothing: a standard-issue, Canadian army, winter uniform and an ensemble of modern retail clothing designed for extreme cold (a down anorak and snowmobile pants). To make the comparison, two subjects sequentially wore the three types of clothing—caribou skin, army uniform, and modern retail—in a still air, uniform thermal environment (where radiant temperatures of all environmental surfaces were equal to air temperature) at −21°C to −23°C (−6°F to −10°F). Thermal imaging quantifies the temperature of the outer surface of clothing, thereby providing key, functionally relevant information on the interface where clothing and environment meet. Under otherwise similar conditions, a low clothing surface temperature indicates superior clothing performance and a reduced rate of heat loss from the body to the environment. Caribou-skin clothing was similar to modern extreme-cold retail clothing: the whole-body composite surface temperature of our subjects wearing caribou-skin clothing was −22.1°C to −22.7°C, compared with −21.6°C in both subjects wearing the modern retail clothing. The army winter uniform (−18.9°C to −20.0°C) was inferior. These quantitative results were mirrored by the subjects’ subjective impressions. A particular advantage of thermal imaging is that it pinpoints locations in clothing where heat leaks occur. Although the two types of modern clothing exhibited heat leaks at zippered structures (even though fully closed), the caribou-skin clothing evaded such heat leaks by lacking such structures, because it is donned over the head. The integral hood characteristic of a caribou-skin parka was also superior in comparison to the detachable hood of the army uniform.Les vĂȘtements de protection sont essentiels Ă  l’existence humaine dans l’Arctique, et les vĂȘtements en peau de caribou y jouent un rĂŽle vital depuis des millĂ©naires. MĂȘme si les gens qui ont Ă©voluĂ© dans le Nord vantent souvent les mĂ©rites des vĂȘtements en peau de caribou, peu d’études scientifiques ont Ă©tĂ© rĂ©alisĂ©es au sujet de leurs propriĂ©tĂ©s. Nous nous sommes servi d’imagerie thermique infrarouge dans le cadre d’une Ă©tude pilote visant Ă  comparer les vĂȘtements en peau de caribou authentique cousus par des couturiĂšres inuites traditionnelles Ă  deux autres types de vĂȘtements pour temps froid : un uniforme d’hiver standard de l’ArmĂ©e canadienne et un ensemble de vĂȘtements modernes du dĂ©tail conçus pour des froids extrĂȘmes (un anorak en duvet et des pantalons de motoneige). À des fins de comparaison, deux sujets ont portĂ©, dans l’ordre sĂ©quentiel, les trois types de vĂȘtements — vĂȘtement en peau de caribou, uniforme de l’armĂ©e et vĂȘtements modernes du dĂ©tail — dans des conditions de vent nul thermique uniforme (oĂč les tempĂ©ratures radiatives de toutes les surfaces environnementales sont Ă©gales Ă  la tempĂ©rature de l’air) moyennant des tempĂ©ratures allant de −21 °C Ă  −23 °C (de −6 °F Ă  −10 °F). L’imagerie thermique quantifie la tempĂ©rature de la surface extĂ©rieure du vĂȘtement, ce qui permet d’obtenir de l’information fonctionnellement pertinente et essentielle sur le point de rencontre du vĂȘtement et de l’environnement. Dans des conditions par ailleurs semblables, la faible tempĂ©rature du vĂȘtement en surface indique un rendement supĂ©rieur pour ce vĂȘtement et un taux rĂ©duit de perte de chaleur du corps Ă  l’environnement. Les vĂȘtements en peau de caribou ont donnĂ© des rĂ©sultats semblables aux vĂȘtements pour froid extrĂȘme modernes du dĂ©tail : la tempĂ©rature composite du corps entier de nos sujets portant les vĂȘtements en peau de caribou variait de −22,1 °C Ă  −22,7 °C, comparativement Ă  −21,6 °C chez les deux sujets portant les vĂȘtements modernes du dĂ©tail. Les tempĂ©ratures de l’uniforme d’hiver de l’armĂ©e Ă©taient infĂ©rieures (de −18,9 °C Ă  −20,0 °C). Ces rĂ©sultats quantitatifs cadraient avec les impressions subjectives des sujets. Un des avantages particuliers de l’imagerie thermique, c’est qu’elle permet de repĂ©rer lĂ  oĂč les pertes de chaleur se produisent dans les vĂȘtements. Bien que les deux types de vĂȘtements modernes perdaient de la chaleur Ă  l’endroit des fermetures Ă©clair (mĂȘme si elles Ă©taient fermĂ©es complĂštement), les vĂȘtements en peau de caribou n’affichaient pas de telles pertes de chaleur en raison de l’absence de structures de ce genre parce que ces vĂȘtements s’enfilent par la tĂȘte. Par ailleurs, il y a lieu de noter que la caractĂ©ristique intĂ©grale du capuchon du parka en peau de caribou Ă©tait Ă©galement supĂ©rieure Ă  celle du capuchon amovible de l’uniforme militaire

    Thermal Imaging and Physiological Analysis of Cold-Climate Caribou-Skin Clothing

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    Protective clothing is essential for human existence in the Arctic, and caribou-skin clothing has played a pivotal role for millennia. Although people with northern experience often extol caribou-skin clothing, few scientific studies have investigated its properties. We used infrared thermal imaging in a pilot study to compare authentic caribou-skin clothing sewn by traditional Inuit seamstresses with two other types of cold-weather clothing: a standard-issue, Canadian army, winter uniform and an ensemble of modern retail clothing designed for extreme cold (a down anorak and snowmobile pants). To make the comparison, two subjects sequentially wore the three types of clothing—caribou skin, army uniform, and modern retail—in a still air, uniform thermal environment (where radiant temperatures of all environmental surfaces were equal to air temperature) at −21°C to −23°C (−6°F to −10°F). Thermal imaging quantifies the temperature of the outer surface of clothing, thereby providing key, functionally relevant information on the interface where clothing and environment meet. Under otherwise similar conditions, a low clothing surface temperature indicates superior clothing performance and a reduced rate of heat loss from the body to the environment. Caribou-skin clothing was similar to modern extreme-cold retail clothing: the whole-body composite surface temperature of our subjects wearing caribou-skin clothing was −22.1°C to −22.7°C, compared with −21.6°C in both subjects wearing the modern retail clothing. The army winter uniform (−18.9°C to −20.0°C) was inferior. These quantitative results were mirrored by the subjects’ subjective impressions. A particular advantage of thermal imaging is that it pinpoints locations in clothing where heat leaks occur. Although the two types of modern clothing exhibited heat leaks at zippered structures (even though fully closed), the caribou-skin clothing evaded such heat leaks by lacking such structures, because it is donned over the head. The integral hood characteristic of a caribou-skin parka was also superior in comparison to the detachable hood of the army uniform

    Variational Problems Involving a Caputo-Type Fractional Derivative

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    We study calculus of variations problems, where the Lagrange function depends on the Caputo-Katugampola fractional derivative. This type of fractional operator is a generalization of the Caputo and the Caputo–Hadamard fractional derivatives, with dependence on a real parameter ρ. We present sufficient and necessary conditions of first and second order to determine the extremizers of a functional. The cases of integral and holomonic constraints are also considered
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