Automatic holographic droplet analysis for liquid fuel sprays

The basic scheme for automated holographic analysis involves an optical system for reconstruction of the three dimensional real image of the droplet field, a spatial scanning system to transport a digitizing X-y image sensor through the real image, and processing algorithms for droplet recognition which establish the droplet sizes and positions. The hardware for system demonstrated includes the expanded and collimated beam from a 5 mW helium-neon laser for hologram reconstruction, an imaging lens for magnification of the real image field, and a video camera and digitizer providing 512-by-512 pixel resolution with 8-bit digitization. A mechanical stage is used to scan the hologram in three dimensional space, maintaining constant image magnification. A test droplet hologram is used for development and testing of the image processing algorithms

Aboriginal Subsistence Whaling in Greenland: The Case of Qeqertarsuaq Municipality in West Greenland

Policy debates in the International Whaling Commission (IWC) about aboriginal subsistence whaling focus on the changing significance of whaling in the mixed economies of contemporary Inuit communities. In Greenland, Inuit hunters have taken whales for over 4000 years as part of a multispecies pattern of marine harvesting. However, ecological dynamics, Euroamerican exploitation of the North Atlantic bowhead whale (Balaena mysticetus), Danish colonial policies, and growing linkages to the world economy have drastically altered whaling practices. Instead of using the umiaq and hand-thrown harpoons, Greenlandic hunters today use harpoon cannons mounted on fishing vessels and fiberglass skiffs with powerful outboard motors. Products from minke whales (Balaenoptera acutorostrata) and fin whales (Balaenoptera physalus) provide both foods for local consumption and limited amounts of cash, obtained through the sale of whale products for Greenlandic foods to others. Greenlanders view this practice as a form of sustainable development, where local renewable resources are used to support livelihoods that would otherwise be dependent upon imported goods. Export of whale products from Greenland is prohibited by law. However, limited trade in whale products within the country is consistent with longstanding Inuit practices of distribution and exchange. Nevertheless, within the IWC critics argue that even limited commiditization of whale products could lead to overexploitation should hunters seek to pursue profit-maximization strategies. Debates continue about the appropriateness of cash and commoditization in subsistence whaling in Qeqertarsuaq Municipality in West Greenland, demonstrating that despite significant changes, whaling is an integral part of Greenland's mixed economy and a vital component of Greenlandic Inuit cultural identity. The social organization of whaling continues to be kinship-based and Greenlandic foods, including whale products, are prominent in local diets and in cultural celebrations. The research reveals that Greenlanders participate in whaling not to maximize profits but in order to sustain cultural traditions and to reduce dependency on tenuous links to the world economy.Key words: Greenland, Qeqertarsuaq Municipality, aboriginal subsistence whaling, Inuit whaling, mixed economy, minke whale,fin whale, International Whaling Commission Les débats sur les politiques concernant la chasse de subsistance à la baleine, au sein de la Commission baleinière internationale (CBI), tournent autour du changement de signification de la chasse dans l'économie mixte des communautés inuit contemporaines. Au Groenland, les chasseurs inuit capturent des baleines depuis plus de 4000 ans, dans le cadre d'un prélèvement polyvalent d'espèces marines. Cependant, la dynamique écologique, l'exploitation euro-américaine de la baleine boréale (Balaena mysticetus) dans l'Atlantique Nord, les politiques coloniales du Danemark, et les liens de plus en plus forts avec l'économie mondiale ont changé radicalement les pratiques de chasse à la baleine. Au lieu d'utiliser l'oumiak et les harpons lancés à la main, les chasseurs groenlandais d'aujourd'hui utilisent des canons lance-harpon montés sur des bateaux de pêche, et des embarcations légères en fibre de verre équipées de puissants moteurs hors-bord. Les produits du petit rorqual (Balaenoptera acutorostrata) et du rorqual commun (Balaenoptera physalus) fournissent à la fois de la nourriture pour la consommation locale et un peu d'argent liquide, provenant de la vente de ces produits pour la consommation alimentaire à l'extérieur de la communauté. Les Groenlandais voient cette pratique comme une forme de développement durable, où des ressources renouvelables locales sont employées pour entretenir un style de vie qui dépendrait autrement de biens importés. L'exportation de produits baleiniers est interdite par la loi au Groenland, mais le commerce limité de produits baleiniers à l'intérieur du pays est en accord avec la longue tradition inuit de distribution et d'échange. Des critiques au sein de la CBI soutiennent cependant que la commercialisation des produits baleiniers, même à faible échelle, pourrait amener une surexploitation si les chasseurs cherchaient à poursuivre des stratégies de maximisation des bénéfices. Les débats continuent pour savoir si l'argent liquide et la transformation des produits baleiniers en marchandises sont appropriés dans le cadre de la chasse de subsistance, et si les régimes de gestion indigènes sont capables d'assurer la protection des stocks de baleines. Cette étude de cas décrit la chasse contemporaine à la baleine dans la municipalité de Qeqertarsuaq dans le Groenland occidental, et montre qu'en dépit de changements significatifs, la chasse à la baleine fait partie intégrante de l'économie mixte du Groenland et qu'elle est une composante vitale de l'identité culturelle inuit du Groenland. L'organisation sociale de la chasse à la baleine continue d'être fondée sur les liens de parenté, et la nourriture groenlandaise, y compris les produits baleiniers, a une place de choix dans l'alimentation et les fêtes culturelles locales. La recherche révèle que les Groenlandais participent à la chasse non pour maximiser leurs bénéfices, mais pour maintenir des traditions culturelles et réduire leur dépendance à l'égard des liens ténus qui les relient à l'économie mondiale.Mots clés: Groenland, municipalité de Qeqertarsuaq, chasse aborigène de subsistance à la baleine, chasse inuit à la baleine, économie mixte, petit rorqual, rorqual commun, Commission baleinière international

The Dimer Model for k-phase Organic Superconductors

We prove that the upper electronic bands of k-phase BEDT-TTF salts are adequately modeled by an half-filled tight-binding lattice with one site per cell. The band parameters are derived from recent ab-initio calculations, getting a very simple but extremely accurate one-electron picture. This picture allows us to solve the BCS gap equation adopting a real-space pairing potential. Comparison of the calculated superconducting properties with the experimental data points to isotropic s_0-pairing. Residual many-body or phonon-mediated interactions offer a plausible explanation of the large variety of physical properties observed in k-phase BEDT-TTF salts.Comment: 8 pages, 6 PostScript figures, uses RevTe

Development of West Greenlandic Markets for Country Foods Since the 18th Century

Local markets for country foods have a history in West Greenland dating back to the early 18th century. After Danish colonization in 1721, Greenlanders gradually began selling these foods (West Greenlandic: kalaalimerngit), which included seal, whale, caribou, fish, and birds - first to the Danes and later to other Greenlandic Inuit. This trade was a significant transformation of pre-contact Inuit exchange practices. In the 18th and early 19th centuries, the trade was largely between Greenlandic hunters and Danes employed by the colonial trade or by the church. Later in the 19th century, these institutions employed increasing numbers of indigenous Greenlanders. Economic specialization gradually became more pronounced within Greenlandic society, and cash became more prominent in local economies. Greenlandic hunters increasingly sold country foods to other Greenlanders earning wages. These practices continue today, with hunters regularly selling country foods in many towns at the local kalaalimineerniarfik (literally, "place where Greenlandic foods are sold"), to institutions such as schools or senior citizens' homes and in large stores. Today, Greenland's Home Rule government is promoting local country food markets as one strategy for sustainable development. The goals are to promote the use of nutritious and culturally valued foods on a sustainable basis and to provide economic opportunities for local hunters, particularly in outlying settlements. The history of Greenland's system for marketing country foods highlights some issues that may influence the contribution of country foods to sustainable community development in the Arctic.L'existence d'un marché régional des denrées tirées de la nature dans le Groenland occidental est attesté depuis le début du XVIIIe siècle. Après la colonisation danoise en 1721, les Groenlandais ont commencé à vendre graduellement ces produits alimentaires (kalaalimerngit, en Groenlandais occidental) - qui incluent phoque, baleine, renne, poisson et oiseaux - d'abord aux Danois, puis à d'autres Inuit du Groenland. Ce commerce marquait un changement important dans les pratiques d'échange préeuropéennes des Inuit. Aux XVIIIe et XIXe siècles, le commerce avait cours surtout entre chasseurs groenlandais et Danois travaillant pour l'église ou le commerce avec les colonies. Au cours du XIXe siècle, ces institutions employèrent un nombre croissant d'autochtones groenlandais. La spécialisation économique devint graduellement plus prononcée au sein de la société groenlandaise, et l'argent plus dominant dans l'économie régionale. Les chasseurs groenlandais vendirent de plus en plus de denrées tirées de la nature à d'autres Groenlandais qui gagnaient un salaire. Ces pratiques continuent aujourd'hui, les chasseurs vendant régulièrement ces denrées dans de nombreuses agglomérations, au kalaalimineerniarfik (littéralement «place où est vendue la nourriture groenlandaise»), à des institutions comme écoles ou foyers pour personnes âgées, et dans des magasins plus grands. Aujourd'hui, le gouvernement autonome du Groenland favorise l'existence des marchés où sont vendues ces denrées locales tirées de la nature, comme une des stratégies de développement durable. Les buts sont de promouvoir l'utilisation, sur une base durable, d'aliments nutritifs et valorisés au plan culturel, ainsi que d'offrir aux chasseurs locaux des ouvertures économiques, en particulier dans les habitats éloignés. L'histoire du système groenlandais de mise en marché des denrées tirées de la nature souligne certains des enjeux qui peuvent influencer la contribution de ces denrées au développement durable des collectivités dans l'Arctique

Optimizing time allocation for network defence

The presence of unpatched, exploitable vulnerabilities in software is a prerequisite for many forms of cyberattack. Because of the almost inevitable discovery of a vulnerability and creation of an exploit for all types of software, multiple layers of security are usually used to protect vital systems from compromise. Accordingly, attackers seeking to access protected systems must circumvent all of these layers. Resource- and budget-constrained defenders must choose when to execute actions such as patching, monitoring and cleaning infected systems in order to best protect their networks. Similarly, attackers must also decide when to attempt to penetrate a system and which exploit to use when doing so. We present an approach to modelling computer networks and vulnerabilities that can be used to find the optimal allocation of time to different system defence tasks. The vulnerabilities, state of the system and actions by the attacker and defender are used to build partially observable stochastic games. These games capture the uncertainty about the current state of the system and the uncertainty about the future. The solution to these games is a policy, which indicates the optimal actions to take for a given belief about the current state of the system. We demonstrate this approach using several different network configurations and types of player. We consider a trade-off for the system administrator, where they must allocate their time to performing either security-related tasks or performing other required non-security tasks. The results presented highlight that, with the requirement for other tasks to be performed, following the optimal policy means spending time on only the most essential security-related tasks, while the majority of time is spent on non-security tasks

Recent developments in the determination of the amplitude and phase of quantum oscillations for the linear chain of coupled orbits

De Haas-van Alphen oscillations are studied for Fermi surfaces (FS) illustrating the model proposed by Pippard in the early sixties, namely the linear chain of orbits coupled by magnetic breakdown. This FS topology is relevant for many multiband quasi-two dimensional (q-2D) organic metals such as $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ and $\theta$-(BEDT-TTF)$_4$CoBr$_4$(C$_6$H$_4$Cl$_2$) which are considered in detail. Whereas the Lifshits-Kosevich model only involves a first order development of field- and temperature-dependent damping factors, second order terms may have significant contribution on the Fourier components amplitude for such q-2D systems at high magnetic field and low temperature. The strength of these second order terms depends on the relative value of the involved damping factors, which are in turns strongly dependent on parameters such as the magnetic breakdown field, effective masses and, most of all, effective Land\'{e} factors. In addition, the influence of field-dependent Onsager phase factors on the oscillation spectra is considered.Comment: arXiv admin note: text overlap with arXiv:1304.665