1,453 research outputs found

    Handbook for estimating toxic fuel hazards

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    Computer program predicts, from readily available meteorological data, concentration and dosage fields downwind from ground-level and elevated sources of toxic fuel emissions. Mathematical model is applicable to hot plume rise from industrial stacks and should also be of interest to air pollution meteorologists

    A factor in oat hulls essential for the growth of chicks

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    Experiments were conducted to determine whether or not oat hulls contain a factor or factors essential for the growth of the chick. When 20 percent of oat hulls was added to a ration composed of oat groats, minerals, cod-liver oil and dried skimmilk or dried buttermilk, an increase in growth resulted. An increase in growth was obtained by supplementing the alcohol:precipitate factor deficient ration of Schumacher et al (24) with yeast or choline, and the occurrence of perosis was practically eliminated. The addition of 20 percent oat hulls to this basal ration caused an increase in growth. The results obtained when oat hulls were added to -the two rations indicated that oat hul1s contained a factor or factors present in yeast, dried skimmilk and dried buttermilk that are essential for the growth of the chick

    Understanding Copepod Life-History and Diversity using a Next-Generation Zooplankton Model

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    The main goal of our project is to understand the patterns of diversity and biogeography in marine copepods. To achieve this goal, we developed a unique modeling framework to simulate the trade-offs between growth, development, and fecundity in marine copepods. We developed a new approach to modeling growth and development in metazoans. We applied this approach to marine copepods, and used it to understand relationships between copepod body size and temperature, copepod biodiversity patterns, and copepod biogeography. This project also provided support for experiments to look at how copepod body size impacts the particle size spectrum. We used our model to explain why marine copepods and other organisms with strong associations between body size and temperature should be expected to deviate from the temperature-diversity relationship that emerges from classic metabolic theory. We also used a novel emergent modeling approach to explore how temperature and chlorophyll cycles influence copepod biogeography

    Diffusion couple studies of the Ni-Bi-Sn system

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    Investigations of Ni-Bi-Sn system were performed in order to inquire the phase diagram and to assess some diffusion kinetic parameters. For this purpose diffusion couples consisting of solid nickel (preliminary electroplated with tin) and liquid Bi-Sn phase were annealed at 370 °C. Three compositions (0.8, 0.6 and 0.4 mole fractions Sn) of the Bi-Sn melts were chosen. Annealing times from 24 to 216 h were applied. The phase and chemical compositions of the contact zone were determined by means of electron scanning microscope. It was confirmed that the diffusion layers consist mainly of Ni3Sn4 but other intermetallic phases grow as well. For the first time metastable Ni-Sn phases as NiSn and NiSn8 (NiSn9) were observed in metallurgical alloys (i.e. not in electroplated samples). The existence of a ternary compound previously reported in the literature was confirmed. More than one ternary Ni-Bi-Sn compounds might possibly be admitted. A growth coefficient of (2.29 ± 0.02) x 10-15 m2 s-1 was obtained. It was found that the apparent activation energy for diffusion layers growth (18 ± 8 kJ mol-1) is inferior to that one assessed at growth from solid state Bi-Sn mixtures (88 ± 12 kJ mol-1)

    Poultry

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    Getting winter eggs from hens / D. C. Kennard and V. D. Chamberlin -- The protein requirements of growing pullets / R. M. Bethke, Paul R. Record and D. C. Kennard -- Coarse versus fine mash / D. C. Kennard -- Chicken vices / D. C. Kennard -- Tipping the beaks / D. C. Kennard -- Use of woven wire in poultry keeping -- Sun parlors for chick

    Thermal denaturation of fluctuating finite DNA chains: the role of bending rigidity in bubble nucleation

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    Statistical DNA models available in the literature are often effective models where the base-pair state only (unbroken or broken) is considered. Because of a decrease by a factor of 30 of the effective bending rigidity of a sequence of broken bonds, or bubble, compared to the double stranded state, the inclusion of the molecular conformational degrees of freedom in a more general mesoscopic model is needed. In this paper we do so by presenting a 1D Ising model, which describes the internal base pair states, coupled to a discrete worm like chain model describing the chain configurations [J. Palmeri, M. Manghi, and N. Destainville, Phys. Rev. Lett. 99, 088103 (2007)]. This coupled model is exactly solved using a transfer matrix technique that presents an analogy with the path integral treatment of a quantum two-state diatomic molecule. When the chain fluctuations are integrated out, the denaturation transition temperature and width emerge naturally as an explicit function of the model parameters of a well defined Hamiltonian, revealing that the transition is driven by the difference in bending (entropy dominated) free energy between bubble and double-stranded segments. The calculated melting curve (fraction of open base pairs) is in good agreement with the experimental melting profile of polydA-polydT. The predicted variation of the mean-square-radius as a function of temperature leads to a coherent novel explanation for the experimentally observed thermal viscosity transition. Finally, the influence of the DNA strand length is studied in detail, underlining the importance of finite size effects, even for DNA made of several thousand base pairs.Comment: Latex, 28 pages pdf, 9 figure

    Projecting Global Mangrove Species and Community Distributions under Climate Change

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    Given the multitude of ecosystem services provided by mangroves, it is important to understand their potential responses to global climate change. Extensive reviews of the literature and manipulative experiments suggest that mangroves will be impacted by climate change, but few studies have tested these predictions over large scales using statistical models. We provide the first example of applying species and community distribution models (SDMs and CDMs, respectively) to coastal mangroves worldwide. Species distributions were modeled as ensemble forecasts using BIOMOD. Distributions of mangrove communities with high species richness were modeled in three ways: as the sum of the separate SDM outputs, as binary hotspots (with >3 species) using a generalized linear model, and continuously using a general boosted model. Individual SDMs were projected for 12 species with sufficient data and CDMs were projected for 30 species into 2080 using global climate model outputs and a range of sea-level rise projections. Species projected to shift their ranges polewards by at least 2 degrees of latitude consistently experience a decrease in the amount of suitable coastal area available to them. Central America and the Caribbean are forecast to lose more mangrove species than other parts of the world. We found that the extent and grain size, at which continuous CDM outputs are examined, independent of the grain size at which the models operate, can dramatically influence the number of pseudo-absences needed for optimal parameterization. The SDMs and CDMs presented here provide a first approximation of how mangroves will respond to climate change given simple correlative relationships between occurrence records and environmental data. Additional, precise georeferenced data on mangrove localities and concerted efforts to collect data on ecological processes across large-scale climatic gradients will enable future research to improve upon these correlative models.Organismic and Evolutionary Biolog

    Handbook for estimating toxic fuel hazards Final report

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    Handbook for estimating toxic fuel hazard downwind from source emissions at Cape Kenned

    The Surprising Oceanography of the Gulf of Maine

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    The oceanography of the Gulf of Maine has changed in ways that have not been seen previously but that are likely to be more common in the future–changes like extreme rapid warming and declines in primary productivity. The changing oceanography has underpinned surprising losses in commercial stocks and endangered species. Because of the rapid rate of change, some have viewed the Gulf of Maine as a window into the ocean’s future, with the idea that lessons learned can be applied in places that have yet to experience similar rapid changes. We can examine the dynamics, origin, and implications of surprising oceanographic conditions–conditions that would have been considered unlikely based on recent prior experience. Based on a formal statistical definition of climate surprises, the frequency of oceanographic surprises in the Gulf of Maine is higher and has increased faster than what would be expected, even given underlying trends. Oceanographic surprises vary in character from one to the next and are often linked to larger scale shifting oceanography across the North Atlantic. The implications for ecological and human communities, industries, and conservation efforts imply a need for policies that consider adaptation to sudden events as well as long-term changes
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