2,027 research outputs found

    Huge Seebeck coefficients in non-aqueous electrolytes

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    The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in 1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range from T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium nitrate in 1-dodecanol. These striking results open the question of unexpectedly large kosmotrope or "structure making" effects of tetraalkylammonium ions on the structure of alcohols.Comment: Submitted to J. Chem. Phy

    Spatial organization and evolutional period of the epidemic model using cellular automata

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    We investigate epidemic models with spatial structure based on the cellular automata method. The construction of the cellular automata is from the study by Weimar and Boon about the reaction-diffusion equations [Phys. Rev. E 49, 1749 (1994)]. Our results show that the spatial epidemic models exhibit the spontaneous formation of irregular spiral waves at large scales within the domain of chaos. Moreover, the irregular spiral waves grow stably. The system also shows a spatial period-2 structure at one dimension outside the domain of chaos. It is interesting that the spatial period-2 structure will break and transform into a spatial synchronous configuration in the domain of chaos. Our results confirm that populations embed and disperse more stably in space than they do in nonspatial counterparts.Comment: 6 papges,5 figures. published in Physics Review

    The Crucible, v. 2, no. 1

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    A scan of the second edition of a student newspaper published by the Literary Fraternity of the Maine State College in 1874. Several advertisements for Orono and Bangor, Maine, businesses are also included. The first edition of The Crucible, published in August, 1873, is also available through this collection in Digital Commons

    Homeownership and effectiveness of the South Africa government housing subsidy scheme

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    This paper presents findings on the effectiveness of the South Africa government housing subsidy scheme in the delivery of houses to its citizens, thus providing homeownership especially to the low-income group and the disadvantaged poor. The paper also evaluates the usage of the houses by the occupants. The results from the post-occupancy survey of the provided houses revealed that the progressive realization of housing for the low-income and disadvantaged groups is being met as all beneficiaries were South African citizens. The survey also revealed that the beneficiaries living in the subsidized houses were originally allocated the houses by the Gauteng Department of Housing (GDOH), which oversees housing allocation in the province adopted as the site for the study. However, from those originally allocated, it was indicated that some of the beneficiaries were previously living in shacks, while some were homeless (absolute homelessness). Further findings from the survey showed that the original intended use of the houses by the government (private residential use) is what the subsidized houses are being used for as revealed by the respondents. This paper starts with an overview of the literature on this topic and the importance of homeownership, and then presents the results of the analysis and findings of the research. Finally, the paper draws some conclusions and makes recommendations. The originality of this paper is based on the fact that there have been issues surrounding the South Africa government's financial commitment of 5% of its Gross Domestic Product (GDP) is grossly inadequate to overcome its huge housing backlog. Due to the limited study to substantiate if the little devoted GDP is making any impact on the disadvantaged group, the current research contributes to this body of knowledge

    Thermodynamic behaviour and structural properties of an aqueous sodium chloride solution upon supercooling

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    We present the results of a molecular dynamics simulation study of thermodynamic and structural properties upon supercooling of a low concentration sodium chloride solution in TIP4P water and the comparison with the corresponding bulk quantities. We study the isotherms and the isochores for both the aqueous solution and bulk water. The comparison of the phase diagrams shows that thermodynamic properties of the solution are not merely shifted with respect to the bulk. Moreover, from the analysis of the thermodynamic curves, both the spinodal line and the temperatures of maximum density curve can be calculated. The spinodal line appears not to be influenced by the presence of ions at the chosen concentration, while the temperatures of maximum density curve displays both a mild shift in temperature and a shape modification with respect to bulk. Signatures of the presence of a liquid-liquid critical point are found in the aqueous solution. By analysing the water-ion radial distribution functions of the aqueous solution we observe that upon changing density, structural modifications appear close to the spinodal. For low temperatures additional modifications appear also for densities close to that corresponding to a low density configurational energy minimum.Comment: 10 pages, 13 figures, 2 tables. To be published in J. Chem. Phy

    Cannibalism as a life boat mechanism

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    Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one

    Adoption and diffusion of technical capacity-building innovations by small-scale artisanal fishers in Fiji

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    Adoption of innovations by farmers and fishers can depend on factors specific to both individuals and their social contexts. Research on the adoption and diffusion of innovations promoted through capacity-building training can provide lessons to support the design and implementation of future development programs. We assess the adoption, diffusion, and outcomes of a livelihoods training program focused on improving postharvest handling and processing of sea cucumbers in 29 coastal villages in Fiji. One year after delivery of the training program, we conducted interviews with sea cucumber fishers (n = 278) and commercial processors (n = 12), as well as focus group discussions (n = 27) with women to examine: (1) which modes of training (training video, manual, and workshops) were most useful; (2) individual- and community-scale characteristics related to adoption and knowledge sharing; (3) whether training produced long-term changes in processing methods used by fishers; and (4) perceived barriers to adoption. Among fishers who were exposed to two or more modes of training (n = 97), most (65%) reported the workshop and manual to be equally useful. Knowledge about the improved methods was shared by 71% of trained fishers and occurred more frequently among women (80%) than men (64%). Trained fishers used shorter, less variable first cooking durations than untrained fishers, and differences were significant for two of six sea cucumber species groups. Adoption and knowledge sharing was not significantly related to the multiscale characteristics examined (age, gender, education, resource dependence, village population size, market access). Some fishers could not access salt for processing, and others were constrained by patron-client relationships. Our study shows that technical capacity-building can benefit from complementary training modes, however other constraints on adoption (e.g., access to materials, patron-client relationships) may need to be addressed to achieve the full benefits of training programs

    Cracking stability in tapered DCB test pieces

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42750/1/10704_2004_Article_BF00113939.pd

    Modified two-potential approach to tunneling problems

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    One-body quantum tunneling to continuum is treated via the two-potential approach, dividing the tunneling potential into external and internal parts. We show that corrections to this approach can be minimized by taking the separation radius inside the interval determined by simple expressions. The resulting two-potential approach reproduces the resonance energy and its width, both for narrow and wide resonances. We also demonstrate that, without losing its accuracy, the two-potential approach can be modified to a form resembling the R-matrix theory, yet without any uncertainties of the latter related to the choice of the matching radius.Comment: 7 two-column pages, 3 figures, extra-explanation added, Phys. Rev. A, in pres

    Spatiotemporal complexity of a ratio-dependent predator-prey system

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    In this paper, we investigate the emergence of a ratio-dependent predator-prey system with Michaelis-Menten-type functional response and reaction-diffusion. We derive the conditions for Hopf, Turing and Wave bifurcation on a spatial domain. Furthermore, we present a theoretical analysis of evolutionary processes that involves organisms distribution and their interaction of spatially distributed population with local diffusion. The results of numerical simulations reveal that the typical dynamics of population density variation is the formation of isolated groups, i.e., stripelike or spotted or coexistence of both. Our study shows that the spatially extended model has not only more complex dynamic patterns in the space, but also chaos and spiral waves. It may help us better understand the dynamics of an aquatic community in a real marine environment.Comment: 6pages, revtex
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