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Sample records for rangeland-xeric forest continuum

  1. Indigenous exploitation and management of tropical forest resources: an evolutionary continuum in forest-people interactions.

    NARCIS (Netherlands)

    Wiersum, K.F.

    1997-01-01

    Since the early 1980s several new approaches towards forest management, which include active participation of local communities, have been tried out in many tropical regions. As a result of these efforts recognition has increased about the various ways in which many local communities are already

  2. Structural and environmental variations in a continuum of gallery forest/savana stricto sensu in Itumirim, MG

    Directory of Open Access Journals (Sweden)

    Danilo José Santos Gomes

    2013-06-01

    Full Text Available This work verified the possible correlations among the variations of the strucuture, species diversity and variations of the substrate in a tree compartment in a continuum of Gallery Forest/Savana stricto sensu in Itumirim, southern of Minas Gerais. The soils of the areas of Gallery Forest, Transition Forest and Savana stricto sensu presented medium structure, high acidity with pH between 4.5 and 5.0 and high aluminum contents. The structural survey all over the patch presented 1,347 individuals distributed into 39 families, 77 genera and 102 species. The family Fabaceae stood out by the greatest richness of species followed by the families Myrtaceae, Lauraceae and Rubiaceae. The species Protium spruceanum and Myrsine umbellata were superior in all the phytosociological parameters, respectively, for all the areas of Gallery Forest and Savana stricto sensu. In the area of transition , the species Copaifera langsdorffii reached the highest values of basal area and absolute dominance; however, as regards to absolute density and cover value was the species Myrsine umbellata. Shannon's diversity indices (H' and Pielou's equatibility index (J' for the three places were of 3,57, 3,51 and 2,58 and 0,79, 0,88 and 0,77, respectively, for the areas of Gallery Forest, transition Forest and Savana stricto sensu. Through the rectified correspondence analysis (DCA, two groupings in the DCA diagram were found: grouping 1 containing only the three plots corresponding to the Savana stricto sensu; and grouping 2 joining together the other plots sampled encompassing the sites of Gallery and transition Forest.

  3. Functional profiling and distribution of the forest soil bacterial communities along the soil mycorrhizosphere continuum.

    Science.gov (United States)

    Uroz, S; Courty, P E; Pierrat, J C; Peter, M; Buée, M; Turpault, M P; Garbaye, J; Frey-Klett, P

    2013-08-01

    An ectomycorrhiza is a multitrophic association between a tree root, an ectomycorrhizal fungus, free-living fungi and the associated bacterial communities. Enzymatic activities of ectomycorrhizal root tips are therefore result of the contribution from different partners of the symbiotic organ. However, the functional potential of the fungus-associated bacterial communities remains unknown. In this study, a collection of 80 bacterial strains randomly selected and isolated from a soil-ectomycorrhiza continuum (oak-Scleroderma citrinum ectomycorrhizas, the ectomycorrhizosphere and the surrounding bulk soil) were characterized. All the bacterial isolates were identified by partial 16S rRNA gene sequences as members of the genera Burkholderia, Collimonas, Dyella, Mesorhizobium, Pseudomonas, Rhizobium and Sphingomonas. The bacterial strains were then assayed for β-xylosidase, β-glucosidase, N-acetyl-hexosaminidase, β-glucuronidase, cellobiohydrolase, phosphomonoesterase, leucine-aminopeptidase and laccase activities, chitin solubilization and auxin production. Using these bioassays, we demonstrated significant differences in the functional distribution of the bacterial communities living in the different compartments of the soil-ectomycorrhiza continuum. The surrounding bulk soil was significantly enriched in bacterial isolates capable of hydrolysing cellobiose and N-acetylglucosamine. In contrast, the ectomycorrhizosphere appeared significantly enriched in bacterial isolates capable of hydrolysing glucopyranoside and chitin. Notably, chitinase and laccase activities were found only in bacterial isolates belonging to the Collimonas and Pseudomonas genera. Overall, the results suggest that the ectomycorrhizal fungi favour specific bacterial communities with contrasting functional characteristics from the surrounding soil.

  4. Manganese in the litter fall-forest floor continuum of boreal and temperate pine and spruce forest ecosystems

    DEFF Research Database (Denmark)

    Berg, Björn; Erhagen, Björn; Johansson, Maj-Britt

    2015-01-01

    We have reviewed the literature on the role of manganese (Mn) in the litter fall-to-humus subsystem. Available data gives a focus on North European coniferous forests. Manganese concentrations in pine (Pinus spp.) foliar litter are highly variable both spatially and temporally within the same...

  5. Continuum Nanofluidics

    DEFF Research Database (Denmark)

    Hansen, Jesper S; Dyre, Jeppe C; Daivis, Peter

    2015-01-01

    This paper introduces the fundamental continuum theory governing momentum transport in isotropic nanofluidic systems. The theory is an extension of the classical Navier-Stokes equation, and includes coupling between translational and rotational degrees of freedom as well as nonlocal response...... functions that incorporate spatial correlations. The continuum theory is compared with molecular dynamics simulation data for both relaxation processes and fluid flows, showing excellent agreement on the nanometer length scale. We also present practical tools to estimate when the extended theory should...

  6. Continuum mechanics

    CERN Document Server

    Spencer, A J M

    2004-01-01

    The mechanics of fluids and the mechanics of solids represent the two major areas of physics and applied mathematics that meet in continuum mechanics, a field that forms the foundation of civil and mechanical engineering. This unified approach to the teaching of fluid and solid mechanics focuses on the general mechanical principles that apply to all materials. Students who have familiarized themselves with the basic principles can go on to specialize in any of the different branches of continuum mechanics. This text opens with introductory chapters on matrix algebra, vectors and Cartesian ten

  7. Urban Forests

    Science.gov (United States)

    David Nowak

    2016-01-01

    Urban forests (and trees) constitute the second forest resource considered in this report. We specifically emphasize the fact that agricultural and urban forests exist on a continuum defined by their relationship (and interrelationship) with a given landscape. These two forest types generally serve different purposes, however. Whereas agricultural forests are...

  8. Continuum Physics

    CERN Document Server

    Hertel, Peter

    2012-01-01

    This small book on the properties of continuously distributed matter covers a huge field. It sets out the governing principles of continuum physics and illustrates them by carefully chosen examples. These examples comprise structural mechanics and elasticity, fluid media, electricity and optics, thermoelectricity, fluctuation phenomena and more, from Archimedes' principle via Brownian motion to white dwarfs. Metamaterials, pattern formation by reaction-diffusion and surface plasmon polaritons are dealt with as well as classical topics such as Stokes' formula, beam bending and buckling, crystal optics and electro- and magnetooptic effects, dielectric waveguides, Ohm's law, surface acoustic waves, to mention just some.   The set of balance equations for content, flow and production of particles, mass, charge, momentum, energy and entropy is augmented by material, or constitutive equations. They describe entire classes of materials, such as viscid fluids and gases, elastic media, dielectrics or electrical con...

  9. Forests

    Science.gov (United States)

    Louis R. Iverson; Mark W. Schwartz

    1994-01-01

    Originally diminished by development, forests are coming back: forest biomass is accumulating. Forests are repositories for many threatened species. Even with increased standing timber, however, biodiversity is threatened by increased forest fragmentation and by exotic species.

  10. Forest understory plant and soil microbial response to an experimentally induced drought and heat-pulse event: the importance of maintaining the continuum

    Science.gov (United States)

    Isabell von Rein; Arthur Gessler; Katrin Premke; Claudia Keitel; Andreas Ulrich; Zachary E. Kayler

    2016-01-01

    Drought duration and intensity are expected to increase with global climate change. How changes in water availability and temperature affect the combined plant–soil–microorganism response remains uncertain. We excavated soil monoliths from a beech (Fagus sylvatica L.) forest, thus keeping the understory plant–microbe communities intact, imposed an...

  11. Hypogaeic anti epigaeic ant (Hymenoptera: Formicidae) assemblages of atlantic costal rainforest and dry mature and secondary amazon forest in Brazil: Continuums or communities

    OpenAIRE

    H. G Fowler; Delabie, J.H.C.; Moutinho, P. R S [UNESP

    2000-01-01

    Meat, flour and sugar baits were used on the soil surface and buried to examine species composition of the ant fauna in three separate tropical forests in Brazil, and to control for the effect of the regional faunal pool. Compositional mosaic diversities were comparable among areas, bait types and foraging strata. Mosaic diversity was independent of mean assemblage size. The number of unique species per sampling unit was correlated with mean assemblage size. Canonical correspondence analysis ...

  12. Learning-Walk Continuum

    Science.gov (United States)

    Finch, Peter Dallas

    2010-01-01

    The continuum of learning walks can be viewed in stages with various dimensions including frequency, participants, purpose and the presence of an instructional framework within which the instructional practice is viewed. Steps in the continuum progress as the learning walks are conducted more frequently. One way to ensure this is accomplished is…

  13. Notes on continuum mechanics

    CERN Document Server

    Chaves, Eduardo W V

    2013-01-01

    This publication is aimed at students, teachers, and researchers of Continuum Mechanics and focused extensively on stating and developing Initial Boundary Value equations used to solve physical problems. With respect to notation, the tensorial, indicial and Voigt notations have been used indiscriminately.   The book is divided into twelve chapters with the following topics: Tensors, Continuum Kinematics, Stress, The Objectivity of Tensors, The Fundamental Equations of Continuum Mechanics, An Introduction to Constitutive Equations, Linear Elasticity, Hyperelasticity, Plasticity (small and large deformations), Thermoelasticity (small and large deformations), Damage Mechanics (small and large deformations), and An Introduction to Fluids. Moreover, the text is supplemented with over 280 figures, over 100 solved problems, and 130 references.

  14. Computational Continuum Mechanics

    CERN Document Server

    Shabana, Ahmed A

    2011-01-01

    This text presents the theory of continuum mechanics using computational methods. Ideal for students and researchers, the second edition features a new chapter on computational geometry and finite element analysis.

  15. The continuum in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Liotta, R.J. [Royal Inst. of Tech. Stockholm (Sweden). Dept. of Solid State Electronics

    1995-11-01

    The Green function formalism is used to extend the standard (shell-model) treatment of bound states to processes that occur in the continuum part of nuclear spectra. The Berggren and Mittag-Leffler expansions are introduced and analysed. Applications to single-particle and particle-hole resonances are performed. Giant resonances are studied within the framework of the continuum RPA. In all cases it is found that the expansions agree well with the exact calculation. The mechanisms that induce the clustering of nucleons in nuclei are analysed and the corresponding decay processes are discussed in detail. (orig.)

  16. Introduction to continuum mechanics

    CERN Document Server

    Lai, W Michael; Rubin, David

    1996-01-01

    Introduction to Continuum Mechanics is a recently updated and revised text which is perfect for either introductory courses in an undergraduate engineering curriculum or for a beginning graduate course.Continuum Mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation, and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, a

  17. Fundamentals of continuum mechanics

    CERN Document Server

    Rudnicki, John W

    2014-01-01

    A concise introductory course text on continuum mechanics Fundamentals of Continuum Mechanics focuses on the fundamentals of the subject and provides the background for formulation of numerical methods for large deformations and a wide range of material behaviours. It aims to provide the foundations for further study, not just of these subjects, but also the formulations for much more complex material behaviour and their implementation computationally.  This book is divided into 5 parts, covering mathematical preliminaries, stress, motion and deformation, balance of mass, momentum and energ

  18. The MUPPLE competence continuum

    NARCIS (Netherlands)

    Wild, Joanna; Wild, Fridolin; Kalz, Marco; Specht, Marcus; Hofer, Margit

    2009-01-01

    Wild, J., Wild, F., Kalz, M., Specht, M., & Hofer, M. (2009). The MUPPLE competence continuum. In F. Wild, M. Kalz, M. Palmér & D. Müller (Eds.), Proceedings of 2nd Workshop Mash-Up Personal Learning Envrionments (MUPPLE'09). Workshop in conjunction with 4th European Conference on Technology

  19. Numerical continuum mechanics

    CERN Document Server

    Kukudzhanov, Vladimir N

    2013-01-01

    This work focuses on computational methods in continuum thermomechanics. The text is based on the author's lectures, which ensures a didactical and coherent buildup.The main emphasis is put on the presentation of ideas and qualitative considerations, illustrated by specific examples and applications. Conditions and explanations that are essential for the practical application of methods are discussed thoroughly.

  20. The Continuum of Listening

    Science.gov (United States)

    Rud, A. G.; Garrison, Jim

    2007-01-01

    The distinction between "apophatic" and "cataphatic" listening is defined and analyzed. "Apophatic" listening is more or less devoid of cognitivist claims, whereas "cataphatic" listening involves cognition and questioning. Many of the papers in this volume are discussed along the continuum determined by these two types of listening.…

  1. Nonlocal continuum field theories

    CERN Document Server

    2002-01-01

    Nonlocal continuum field theories are concerned with material bodies whose behavior at any interior point depends on the state of all other points in the body -- rather than only on an effective field resulting from these points -- in addition to its own state and the state of some calculable external field. Nonlocal field theory extends classical field theory by describing the responses of points within the medium by functionals rather than functions (the "constitutive relations" of classical field theory). Such considerations are already well known in solid-state physics, where the nonlocal interactions between the atoms are prevalent in determining the properties of the material. The tools developed for crystalline materials, however, do not lend themselves to analyzing amorphous materials, or materials in which imperfections are a major part of the structure. Nonlocal continuum theories, by contrast, can describe these materials faithfully at scales down to the lattice parameter. This book presents a unif...

  2. Continuum mechanics for engineers

    CERN Document Server

    Mase, G Thomas; Mase, George E

    2009-01-01

    Continuum TheoryContinuum MechanicsStarting OverNotationEssential MathematicsScalars, Vectors and Cartesian TensorsTensor Algebra in Symbolic Notation - Summation ConventionIndicial NotationMatrices and DeterminantsTransformations of Cartesian TensorsPrincipal Values and Principal DirectionsTensor Fields, Tensor CalculusIntegral Theorems of Gauss and StokesStress PrinciplesBody and Surface Forces, Mass DensityCauchy Stress PrincipleThe Stress TensorForce and Moment Equilibrium; Stress Tensor SymmetryStress Transformation LawsPrincipal Stresses; Principal Stress DirectionsMaximum and Minimum Stress ValuesMohr's Circles For Stress Plane StressDeviator and Spherical Stress StatesOctahedral Shear StressKinematics of Deformation and MotionParticles, Configurations, Deformations and MotionMaterial and Spatial CoordinatesLangrangian and Eulerian DescriptionsThe Displacement FieldThe Material DerivativeDeformation Gradients, Finite Strain TensorsInfinitesimal Deformation TheoryCompatibility EquationsStretch RatiosRot...

  3. Introduction to continuum mechanics

    CERN Document Server

    Rubin, David; Lai, W Michael

    1994-01-01

    Continuum mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, and the book contains an abundance of illustrative examples and problems, many with solutions. Through the addition of more advanced material (solution of classical elasticity problems, constitutive e

  4. Continuum robots and underactuated grasping

    Directory of Open Access Journals (Sweden)

    N. Giri

    2011-02-01

    Full Text Available We discuss the capabilities of continuum (continuous backbone robot structures in the performance of under-actuated grasping. Continuum robots offer the potential of robust grasps over a wide variety of object classes, due to their ability to adapt their shape to interact with the environment via non-local continuum contact conditions. Furthermore, this capability can be achieved with simple, low degree of freedom hardware. However, there are practical issues which currently limit the application of continuum robots to grasping. We discuss these issues and illustrate via an experimental continuum grasping case study.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  5. Continuum mechanics of anisotropic materials

    CERN Document Server

    Cowin, Stephen C

    2013-01-01

    Continuum Mechanics of Anisotropic Materials(CMAM) presents an entirely new and unique development of material anisotropy in the context of an appropriate selection and organization of continuum mechanics topics. These features will distinguish this continuum mechanics book from other books on this subject. Textbooks on continuum mechanics are widely employed in engineering education, however, none of them deal specifically with anisotropy in materials. For the audience of Biomedical, Chemical and Civil Engineering students, these materials will be dealt with more frequently and greater accuracy in their analysis will be desired. Continuum Mechanics of Anisotropic Materials' author has been a leader in the field of developing new approaches for the understanding of anisotropic materials.

  6. Continuum of Care (COC) Areas

    Data.gov (United States)

    Department of Housing and Urban Development — The purpose of the Continuum of Care (CoC) Homeless Assistance Programs is to reduce the incidence of homelessness in CoC communities by assisting homeless...

  7. Lagrangian continuum dynamics in ALEGRA.

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Michael K. W.; Love, Edward

    2007-12-01

    Alegra is an ALE (Arbitrary Lagrangian-Eulerian) multi-material finite element code that emphasizes large deformations and strong shock physics. The Lagrangian continuum dynamics package in Alegra uses a Galerkin finite element spatial discretization and an explicit central-difference stepping method in time. The goal of this report is to describe in detail the characteristics of this algorithm, including the conservation and stability properties. The details provided should help both researchers and analysts understand the underlying theory and numerical implementation of the Alegra continuum hydrodynamics algorithm.

  8. Submillimeter Continuum Observations of Comets

    Science.gov (United States)

    Jewitt, David

    1998-01-01

    The aim of this proposal was to study the submillimeter continuum emission from comets. The study was based mainly on the exploitation of the world's leading submillimeter telescope, the JCMT (James Clerk Maxwell Telescope) on Mauna Kea. Submillimeter wavelengths provide a unique view of cometary physics for one main reason. The cometary size distribution is such that the scattering cross-section is dominated by small dust grains, while the mass is dominated by the largest particles. Submillimeter continuum radiation samples cometary particles much larger than those sampled by more common observations at shorter (optical and infrared) wavelengths and therefore provides a nearly direct measure of the cometary dust mass.

  9. The geometry of continuum regularization

    Energy Technology Data Exchange (ETDEWEB)

    Halpern, M.B.

    1987-03-01

    This lecture is primarily an introduction to coordinate-invariant regularization, a recent advance in the continuum regularization program. In this context, the program is seen as fundamentally geometric, with all regularization contained in regularized DeWitt superstructures on field deformations.

  10. Homogenization of a Cauchy continuum towards a micromorphic continuum

    Science.gov (United States)

    Hütter, Geralf

    2017-02-01

    The micromorphic theory of Eringen and Mindlin, including special cases like strain gradient theory or Cosserat theory, is widely used to model size effects and localization phenomena. The heuristic construction of such theories based on thermodynamic considerations is well-established. However, the identification of corresponding constitutive laws and of the large number of respective constitutive parameters limits the practical application of such theories. In the present contribution, a closed procedure for the homogenization of a Cauchy continuum at the microscale towards a fully micromorphic continuum is derived including explicit definitions of all involved generalized macroscopic stress and deformation measures. The boundary value problem to be solved on the microscale is formulated either for using static or kinematic boundary conditions. The procedure is demonstrated with an example.

  11. An expedition to continuum theory

    CERN Document Server

    Müller, Wolfgang H

    2014-01-01

    This book introduces field theory as required in solid and fluid mechanics as well as in electromagnetism. It also presents the necessary mathematical framework, namely tensor algebra and tensor calculus, by using an inductive approach, which makes it particularly suitable for beginners. In general, the book can be used in undergraduate classes on continuum theory and, more specifically, in courses on continuum mechanics, for students of physics and engineering alike. The benefits for the readers consist of providing a sound basis of the subject as a whole and of training their ability for solving specific problems in a rational manner.  For this purpose the general laws of nature in terms of the balances for mass, momentum, and energy are applied and combined with constitutive relations, which are material specific. Various examples and homework problems illustrate how to use the theory in daily practice. Numerous mini-biographies have been added to the mathematical text for diversion and amusement.

  12. Finsler-Geometric Continuum Mechanics

    Science.gov (United States)

    2016-05-01

    in time at which a deformable solid body is considered undeformed, following the usual conven- tion of continuum physics.19 A differential manifold M...coordinates and their indices, which are denoted via lowercase rather than capital fonts. A differential manifold m of spatial dimension 3 is identified with a...Aberdeen Proving Ground, MD 21005-5066 primary author’s email: <johnclay@cims.nyu.edu>. Concepts from Finsler differential geometry are applied toward a

  13. Continuum representations of cellular solids

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, M.K.

    1993-09-01

    Cellular materials consist of interconnected struts or plates which form cells. The struts or plates are constructed from a variety of metals, polymers, ceramics and wood products. Cellular materials are often used in impact limiters for shipping containers to protect the contents from accidental impact events. These materials exhibit a variety of complex behavior when subjected to crushing loads. This research focuses on the development of continuum representations of cellular solids that can be used in the finite element analysis of shipping container accidents. A significant portion of this work is the development of a new methodology to relate localized deformations to appropriate constitutive descriptions. This methodology provides the insight needed to select constitutive descriptions for cellular solids that capture the localized deformations that are observed experimentally. Constitutive relations are developed for two different cellular materials, aluminum honeycomb and polyurethane foam. These constitutive relations are based on plasticity and continuum damage theories. Plasticity is used to describe the permanent deformation exhibited by both aluminum honeycomb and polyurethane foam. Continuum damage is needed to capture the change in elastic parameters due to cracking of the polyurethane cell wall materials. The new constitutive description of polyurethane foam is implemented in both static and dynamic finite element codes, and analytical and numerical predictions are compared with available experimental data.

  14. Analogies between continuum dislocation theory, continuum mechanics and fluid mechanics

    Science.gov (United States)

    Silbermann, C. B.; Ihlemann, J.

    2017-03-01

    Continuum Dislocation Theory (CDT) relates gradients of plastic deformation in crystals with the presence of geometrically necessary dislocations. Interestingly, CDT shows striking analogies to other branches of continuum mechanics. The present contribution demonstrates this on two essential kinematical quantities which reflect tensorial dislocation properties: the (resultant) Burgers vector and the dislocation density tensor. First, the limiting process for the (resultant) Burgers vector from an integral to a local quantity is performed analogously to the limiting process from the force vector to the traction vector. By evaluating the balance of forces on a tetrahedral volume element, Cauchy found his famous formula relating traction vector and stress tensor. It is shown how this procedure may be adopted to a continuously dislocated tetrahedron. Here, the conservation of Burger’s vector implicates the introduction of the dislocation density tensor. Second, analogies between the plastic flow of a continuously dislocated solid and the liquid flow of a fluid are highlighted: the resultant Burgers vector of a dislocation ensemble plays a similar role as the (resultant) circulation of a vortex tube. Moreover, both vortices within flowing fluids and dislocations within deforming solids induce discontinuities in the velocity field and the plastic distortion field, respectively. Beyond the analogies, some peculiar properties of the dislocation density tensor are presented as well.

  15. Continuum mechanics of electromagnetic solids

    CERN Document Server

    Maugin, GA

    1988-01-01

    This volume is a rigorous cross-disciplinary theoretical treatment of electromechanical and magnetomechanical interactions in elastic solids. Using the modern style of continuum thermomechanics (but without excessive formalism) it starts from basic principles of mechanics and electromagnetism, and goes on to unify these two fields in a common framework. It treats linear and nonlinear static and dynamic problems in a variety of elastic solids such as piezoelectrics, electricity conductors, ferromagnets, ferroelectrics, ionic crystals and ceramics. Chapters 1-3 are introductory, describing the e

  16. The continuum disordered pinning model.

    Science.gov (United States)

    Caravenna, Francesco; Sun, Rongfeng; Zygouras, Nikos

    Any renewal processes on [Formula: see text] with a polynomial tail, with exponent [Formula: see text], has a non-trivial scaling limit, known as the [Formula: see text]-stable regenerative set. In this paper we consider Gibbs transformations of such renewal processes in an i.i.d. random environment, called disordered pinning models. We show that for [Formula: see text] these models have a universal scaling limit, which we call the continuum disordered pinning model (CDPM). This is a random closed subset of [Formula: see text] in a white noise random environment, with subtle features:Any fixed a.s. property of the [Formula: see text]-stable regenerative set (e.g., its Hausdorff dimension) is also an a.s. property of the CDPM, for almost every realization of the environment.Nonetheless, the law of the CDPM is singular with respect to the law of the [Formula: see text]-stable regenerative set, for almost every realization of the environment. The existence of a disordered continuum model, such as the CDPM, is a manifestation of disorder relevance for pinning models with [Formula: see text].

  17. Nonlocal models in continuum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, N.L. [Los Alamos National Lab., NM (United States); Phan-Thien, N. [Sydney Univ., NSW (Australia). Dept. of Mechanical Engineering

    1993-09-01

    The recent appearance of nonlocal methods is examined in the light of traditional continuum mechanics. A comparison of nonlocal approaches in the fields of solid and fluid mechanics reveals that no consistent definition of a nonlocal theory has been used. We suggest a definition based on the violation of the principle of local action in continuum mechanics. From the consideration of the implications of a nonlocal theory based on this definition, we conclude that constitutive relations with nonlocal terms can confuse the traditional separation of the roles between conservation laws and constitutive relations. The diversity of motivations for the nonlocal approaches are presented, resulting primarily from deficiencies in numerical solutions to practical problems. To illustrate these concepts, the history of nonlocal terms in the field of viscoelastic fluids is reviewed. A specific example of a viscoelastic constitutive relation that contains a stress diffusion term is applied to a simple shear flow and found not to be a physical description of any known fluid. We conclude by listing questions that should be asked of nonlocal approaches.

  18. Extension versus Bending for Continuum Robots

    Directory of Open Access Journals (Sweden)

    George Grimes

    2008-11-01

    Full Text Available In this paper, we analyze the capabilities of a novel class of continuous-backbone ("continuum" robots. These robots are inspired by biological "trunks, and tentacles". However, the capabilities of established continuum robot designs, which feature controlled bending but not extension, fall short of those of their biological counterparts. In this paper, we argue that the addition of controlled extension provides dual and complementary functionality, and correspondingly enhanced performance, in continuum robots. We present an interval-based analysis to show how the inclusion of controllable extension significantly enhances the workspace and capabilities of continuum robots.

  19. 77 FR 45367 - Continuum of Care Homeless Assistance Grant Application; Continuum of Care Application

    Science.gov (United States)

    2012-07-31

    ... strategic planning activities, performance, homeless populations, and data collection methods. This... Assistance application which collects data about the CoC's strategic planning activities, performance... URBAN DEVELOPMENT Continuum of Care Homeless Assistance Grant Application; Continuum of Care Application...

  20. The Co-creation Continuum

    DEFF Research Database (Denmark)

    Ind, Nicholas; Iglesias, Oriol; Markovic, Stefan

    2017-01-01

    Co-creation can open up a brand to the outside world and help it to generate relevant innovations. However, there is scarce empirical evidence as to how managers actually use co-creation to connect with customers and other stakeholders and build enduring innovation-oriented relationships with them....... To better understand this, as well as the assumptions of managers and the barriers they encounter in realizing the potential of co-creation, the authors have conducted 20 semi-structured interviews with managers that have led co-creation initiatives for 20 brands. This research finds diverse views of co-creation...... - from tactical market research tool to strategic collaborative innovation method, and shows that brands can be positioned along a continuum between these two polarities. This article also presents the implications for those that want to seize the potential of co-creation....

  1. Physics of the continuum of borromean nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Vaagen, J.S.; Rogde, T. [Dept. of Physics, Univ. of Bergen (Norway); Danilin, B.V. [RRC The Kurchatov Inst., Kurchatov, Moscow (Russian Federation); Ershov, S.N. [JINR, Dubna, Moscow (Russian Federation); Thompson, I.J. [Dept. of Physics, Univ. of Surrey, Guildford (United Kingdom); Zhukov, M.V. [Chalmers Univ. of Technology and Goeteborg Univ., Goeteborg (Sweden); RNBT Collaboration

    1998-06-01

    The continuum states of two-neutron halo nuclei are calculated in the method of hyperspherical harmonics. Using DWIA theory appropriate for dilute halo matter we have probed the structure of the low-lying {sup 6}He continuum via calculations of charge-exchange and inelastic scattering. (orig.)

  2. Continuum Lowering -- A New Perspective

    CERN Document Server

    Crowley, B J B

    2013-01-01

    What is meant by continuum lowering and ionisation potential depression (IPD) in a Coulomb system depends very much upon what question is being asked and whether it relates to equilibrium (equation-of-state) phenomena or non-equilibrium dynamical processes like photoionisation. It is shown that these scenarios are characterised by different values of the IPD. In the former, the ionisation potential of an atom embedded in matter is the difference in the free energy of the many-body system between states of thermodynamic equilibrium differing by the ionisation state of just one atom. Typically, this energy is less than that required to ionise the same atom in vacuo. Probably, the best known example of the IPD determined this way is that given by Stewart and Pyatt (SP). However, it is a common misconception that this formula should apply to the energy of a photon causing photoionisation - a local adiabatic process that occurs on timescales far too short to allow the final state to come into equilibrium, and addi...

  3. Continuum mechanics elasticity, plasticity, viscoelasticity

    CERN Document Server

    Dill, Ellis H

    2006-01-01

    FUNDAMENTALS OF CONTINUUM MECHANICSMaterial ModelsClassical Space-TimeMaterial BodiesStrainRate of StrainCurvilinear Coordinate SystemsConservation of MassBalance of MomentumBalance of EnergyConstitutive EquationsThermodynamic DissipationObjectivity: Invariance for Rigid MotionsColeman-Mizel ModelFluid MechanicsProblems for Chapter 1BibliographyNONLINEAR ELASTICITYThermoelasticityMaterial SymmetriesIsotropic MaterialsIncompressible MaterialsConjugate Measures of Stress and StrainSome Symmetry GroupsRate Formulations for Elastic MaterialsEnergy PrinciplesGeometry of Small DeformationsLinear ElasticitySpecial Constitutive Models for Isotropic MaterialsMechanical Restrictions on the Constitutive RelationsProblems for Chapter 2BibliographyLINEAR ELASTICITYBasic EquationsPlane StrainPlane StressProperties of SolutionsPotential EnergySpecial Matrix NotationThe Finite Element Method of SolutionGeneral Equations for an Assembly of ElementsFinite Element Analysis for Large DeformationsProblems for Chapter 3Bibliograph...

  4. Continuum mechanics of single-substance bodies

    CERN Document Server

    Eringen, A Cemal

    1975-01-01

    Continuum Physics, Volume II: Continuum Mechanics of Single-Substance Bodies discusses the continuum mechanics of bodies constituted by a single substance, providing a thorough and precise presentation of exact theories that have evolved during the past years. This book consists of three parts-basic principles, constitutive equations for simple materials, and methods of solution. Part I of this publication is devoted to a discussion of basic principles irrespective of material geometry and constitution that are valid for all kinds of substances, including composites. The geometrical notions, k

  5. Geometric continuum mechanics and induced beam theories

    CERN Document Server

    R Eugster, Simon

    2015-01-01

    This research monograph discusses novel approaches to geometric continuum mechanics and introduces beams as constraint continuous bodies. In the coordinate free and metric independent geometric formulation of continuum mechanics as well as for beam theories, the principle of virtual work serves as the fundamental principle of mechanics. Based on the perception of analytical mechanics that forces of a mechanical system are defined as dual quantities to the kinematical description, the virtual work approach is a systematic way to treat arbitrary mechanical systems. Whereas this methodology is very convenient to formulate induced beam theories, it is essential in geometric continuum mechanics when the assumptions on the physical space are relaxed and the space is modeled as a smooth manifold. The book addresses researcher and graduate students in engineering and mathematics interested in recent developments of a geometric formulation of continuum mechanics and a hierarchical development of induced beam theories.

  6. Defining and testing a granular continuum element

    OpenAIRE

    Rycroft, Chris H.; Kamrin, Ken; Bazant, Martin Z.

    2008-01-01

    Continuum mechanics relies on the fundamental notion of a mesoscopic volume "element" in which properties averaged over discrete particles obey deterministic relationships. Recent work on granular materials suggests a continuum law may be inapplicable, revealing inhomogeneities at the particle level, such as force chains and slow cage breaking. Here, we analyze large-scale Discrete-Element Method (DEM) simulations of different granular flows and show that a "granular element" can indeed ...

  7. Prioritizing partners across the continuum.

    Science.gov (United States)

    Maly, Mary Beth; Lawrence, Susan; Jordan, M Kim; Davies, William J; Weiss, Michael J; Deitrick, Lynn; Salas-Lopez, Debbie

    2012-11-01

    With the advent of accountable care organizations, bundled payments, value-based purchasing, and penalties for preventable hospital readmission, tight connections and collaboration across the care continuum will become critical to achieve successful patient outcomes and to reduce the cost of care delivery. Lehigh Valley Health Network (LVHN), the largest provider of health services in eastern Pennsylvania, set out on a journey to build collaborative relationships with skilled nursing facilities (SNFs) in their eastern Pennsylvania community. LVHN desired SNF partners with mutual interests in improving quality of care and lowering costs of delivery where possible. Recognizing that not all SNFs are alike, LVHN developed a Collaborative Partner Prioritization Tool to assess and prioritize skilled nursing facilities in an effort to determine those that would make the best collaborators. SNFs were reviewed based on their volume of mutual patients, quality of care delivery, and their perceived willingness to align with LVHN. Six variables were used to assess these facilities, including (1) patient discharge destination volume by SNF; (2) 30-day all-cause readmission rate to an LVHN hospital; (3) Medicare's Nursing Home Compare 5-Star Overall Rating; (4) the health network affiliation of the SNF's medical director; (5) the level of LVHN-employed or -affiliated physician presence at the SNF; and (6) the SNF's current participation in LVHN-sponsored programs and meetings. Through use of the Collaborative Partner Prioritization Tool, it was discovered that roughly 70% of LVHN patients who required skilled nursing care following their inpatient stay received care at 1 of 20 SNFs. Of these, 5 facilities performed well on the 6-variable assessment, deeming them the "Tier 1 Facilities" to initially focus collaborative efforts. LVHN has strategically deployed physician resources and has increased physician presence at these "Tier 1 SNFs." These facilities have also gained remote

  8. Hyperbolic conservation laws in continuum physics

    CERN Document Server

    Dafermos, Constantine M

    2016-01-01

    This is a masterly exposition and an encyclopedic presentation of the theory of hyperbolic conservation laws. It illustrates the essential role of continuum thermodynamics in providing motivation and direction for the development of the mathematical theory while also serving as the principal source of applications. The reader is expected to have a certain mathematical sophistication and to be familiar with (at least) the rudiments of analysis and the qualitative theory of partial differential equations, whereas prior exposure to continuum physics is not required. The target group of readers would consist of (a) experts in the mathematical theory of hyperbolic systems of conservation laws who wish to learn about the connection with classical physics; (b) specialists in continuum mechanics who may need analytical tools; (c) experts in numerical analysis who wish to learn the underlying mathematical theory; and (d) analysts and graduate students who seek introduction to the theory of hyperbolic systems of conser...

  9. Stiffness Control of Surgical Continuum Manipulators.

    Science.gov (United States)

    Mahvash, Mohsen; Dupont, Pierre E

    2011-04-01

    This paper introduces the first stiffness controller for continuum robots. The control law is based on an accurate approximation of a continuum robot's coupled kinematic and static force model. To implement a desired tip stiffness, the controller drives the actuators to positions corresponding to a deflected robot configuration that produces the required tip force for the measured tip position. This approach provides several important advantages. First, it enables the use of robot deflection sensing as a means to both sense and control tip forces. Second, it enables stiffness control to be implemented by modification of existing continuum robot position controllers. The proposed controller is demonstrated experimentally in the context of a concentric tube robot. Results show that the stiffness controller achieves the desired stiffness in steady state, provides good dynamic performance, and exhibits stability during contact transitions.

  10. Continuum mechanics concise theory and problems

    CERN Document Server

    Chadwick, P

    1998-01-01

    Written in response to the dearth of practical and meaningful textbooks in the field of fundamental continuum mechanics, this comprehensive treatment offers students and instructors an immensely useful tool. Its 115 solved problems and exercises not only provide essential practice but also systematically advance the understanding of vector and tensor theory, basic kinematics, balance laws, field equations, jump conditions, and constitutive equations.Readers follow clear, formally precise steps through the central ideas of classical and modern continuum mechanics, expressed in a common, effici

  11. A Universal Continuum of Weight aleph

    CERN Document Server

    Dow, A; Dow, Alan; Hart, Klaas Pieter

    2001-01-01

    We prove that every continuum of weight aleph_1 is a continuous image of the Cech-Stone-remainder R^* of the real line. It follows that under CH the remainder of the half line [0,infty) is universal among the continua of weight c. We complement this result by showing that 1) under MA every continuum of weight less than c is a continuous image of R^* 2) in the Cohen model the long segment of length omega_2+1 is not a continuous image of R^*, and 3) PFA implies that I_u is not a continuous image of R^*, whenever u is a c-saturated ultrafilter.

  12. Cosmological measurements with forthcoming radio continuum surveys

    CSIR Research Space (South Africa)

    Raccanelli, A

    2012-08-01

    Full Text Available We present forecasts for constraints on cosmological models that can be obtained using the forthcoming radio continuum surveys: the wide surveys with the Low Frequency Array (LOFAR) for radio astronomy, theAustralian SquareKilometreArray Pathfinder...

  13. Continuum percolation of isotropically oriented circular cylinders

    Science.gov (United States)

    Sangare, D.; Adler, P. M.

    2009-05-01

    The continuum percolation of circular cylinders has been studied for various values of the aspect ratio b' . The percolation threshold is shown to have a maximum for b'≈2 when the cylinder length is equal to its diameter. Other quantities such as the average intersection volume and the porosity also possess a maximum for this value.

  14. Questioning the continuum: specialization in rock climbing

    Science.gov (United States)

    Sean Nelb; Rudy M. Schuster

    2008-01-01

    Recreation specialization was originally conceived as a behavioral continuum ranging from general to more particular behaviors within an activity. It was assumed that an individual progressed from one subactivity to another in a hierarchical order. In recent years the practicality of such ordering has come under doubt; it may be possible to specialize in individual...

  15. Continuum balances from extended Hamiltonian dynamics.

    Science.gov (United States)

    Giusteri, Giulio G; Podio-Guidugli, Paolo; Fried, Eliot

    2017-06-14

    The classical procedure devised by Irving and Kirkwood in 1950 and completed slightly later by Noll produces counterparts of the basic balance laws of standard continuum mechanics starting from an ordinary Hamiltonian description of the dynamics of a system of material points. Post-1980 molecular dynamics simulations of the time evolution of such systems use extended Hamiltonians such as those introduced by Andersen, Nosé, and Parrinello and Rahman. The additional terms present in these extensions affect the statistical properties of the system so as to capture certain target phenomenologies that would otherwise be beyond reach. We here propose a physically consistent application of the Irving-Kirkwood-Noll procedure to the extended Hamiltonian systems of material points. Our procedure produces balance equations at the continuum level featuring non-standard terms because the presence of auxiliary degrees of freedom gives rise to additional fluxes and sources that influence the thermodynamic and transport properties of the continuum model. Being aware of the additional contributions may prove crucial when designing multiscale computational schemes in which information is exchanged between the atomistic and continuum levels.

  16. Whole Language in Perspective: A Teacher's Continuum.

    Science.gov (United States)

    Christensen, K. Eleanor

    Whole language represents only one of many good concepts about teaching reading to children, but it is not for everybody. Because whole language is a philosophy rather than a specific method, educational practitioners can incorporate different aspects of this philosophy to different degrees. If teachers think of a continuum of theoretical bases…

  17. Design of an environmentally interactive continuum manipulator

    NARCIS (Netherlands)

    Bakker, D.L.; Matsuura, D.; Takeda, Y; Herder, J.L.; Chang, S.H.

    2015-01-01

    Continuum manipulators are high degree of freedom structures that can use their increased degrees of freedom to navigate through an environment with obstacles. This type of manipulator is underactuated, which make them promising for adapting to their environments. However, current research is mainly

  18. Continuum Modeling in the Physical Sciences

    NARCIS (Netherlands)

    Groesen, van E.; Molenaar, J.

    2007-01-01

    Mathematical modeling—the ability to apply mathematical concepts and techniques to real-life systems—has expanded considerably over the last decades, making it impossible to cover all of its aspects in one course or textbook. Continuum Modeling in the Physical Sciences provides an extensive

  19. Parental Involvement to Parental Engagement: A Continuum

    Science.gov (United States)

    Goodall, Janet; Montgomery, Caroline

    2014-01-01

    Based on the literature of the field, this article traces a continuum between parental involvement with schools, and parental engagement with children's learning. The article seeks to shed light on an area of confusion; previous research has shown that different stakeholder groups understand "parental engagement" in different ways.…

  20. An appraisal of the classic forest succession paradigm with the shade tolerance index

    Science.gov (United States)

    Jean Lienard; Ionut Florescu; Nikolay. Strigul

    2015-01-01

    We revisit the classic theory of forest succession that relates shade tolerance and species replacement and assess its validity to understand patch-mosaic patterns of forested ecosystems of the USA. We introduce a macroscopic parameter called the “shade tolerance index” and compare it to the classic continuum index in southern Wisconsin forests. We exemplify shade...

  1. The geometrical language of continuum mechanics

    CERN Document Server

    Epstein, Marcelo

    2010-01-01

    This book presents the fundamental concepts of modern differential geometry within the framework of continuum mechanics. It is divided into three parts of roughly equal length. The book opens with a motivational chapter to impress upon the reader that differential geometry is indeed the natural language of continuum mechanics or, better still, that the latter is a prime example of the application and materialization of the former. In the second part, the fundamental notions of differential geometry are presented with rigor using a writing style that is as informal as possible. Differentiable manifolds, tangent bundles, exterior derivatives, Lie derivatives, and Lie groups are illustrated in terms of their mechanical interpretations. The third part includes the theory of fiber bundles, G-structures, and groupoids, which are applicable to bodies with internal structure and to the description of material inhomogeneity. The abstract notions of differential geometry are thus illuminated by practical and intuitivel...

  2. Mesoscopic and continuum modelling of angiogenesis

    KAUST Repository

    Spill, F.

    2014-03-11

    Angiogenesis is the formation of new blood vessels from pre-existing ones in response to chemical signals secreted by, for example, a wound or a tumour. In this paper, we propose a mesoscopic lattice-based model of angiogenesis, in which processes that include proliferation and cell movement are considered as stochastic events. By studying the dependence of the model on the lattice spacing and the number of cells involved, we are able to derive the deterministic continuum limit of our equations and compare it to similar existing models of angiogenesis. We further identify conditions under which the use of continuum models is justified, and others for which stochastic or discrete effects dominate. We also compare different stochastic models for the movement of endothelial tip cells which have the same macroscopic, deterministic behaviour, but lead to markedly different behaviour in terms of production of new vessel cells. © 2014 Springer-Verlag Berlin Heidelberg.

  3. Nonlinear continuum mechanics and large inelastic deformations

    CERN Document Server

    Dimitrienko, Yuriy I

    2010-01-01

    This book provides a rigorous axiomatic approach to continuum mechanics under large deformation. In addition to the classical nonlinear continuum mechanics - kinematics, fundamental laws, the theory of functions having jump discontinuities across singular surfaces, etc. - the book presents the theory of co-rotational derivatives, dynamic deformation compatibility equations, and the principles of material indifference and symmetry, all in systematized form. The focus of the book is a new approach to the formulation of the constitutive equations for elastic and inelastic continua under large deformation. This new approach is based on using energetic and quasi-energetic couples of stress and deformation tensors. This approach leads to a unified treatment of large, anisotropic elastic, viscoelastic, and plastic deformations. The author analyses classical problems, including some involving nonlinear wave propagation, using different models for continua under large deformation, and shows how different models lead t...

  4. Continuum RPA calculation of escape widths

    Energy Technology Data Exchange (ETDEWEB)

    Vertse, T. (Inst. of Nuclear Research, Hungarian Academy of Sciences, Debrecen (Hungary)); Curutchet, P.; Liotta, R.J. (Manne Siegbahn Inst. of Physics, Stockholm (Sweden)); Bang, J. (Niels Bohr Inst., Copenhagen (Denmark)); Giai, N. van (Inst. de Physique Nucleaire, 91 - Orsay (France))

    1991-07-25

    Particle-hole partial decay widths are calculated within the continuum RPA exactly, i.e. without any further approximation, in a square well plus Coulomb potential and using a separable residual interaction. The results are compared with the ones obtained by making pole expansions of the single-particle Green functions (Berggren and Mittag-Leffler). It is found that the Berggren and Mittag-Leffler expansions give results in good agreement with the 'exact' ones. (orig.).

  5. On continuum driven winds from rotating stars

    OpenAIRE

    Shacham, Tomer; Shaviv, Nir J.

    2012-01-01

    We study the dynamics of continuum driven winds from rotating stars, and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are sufficiently concentrated towards the poles to spin up the star. A twin-lobe structure of the ejected nebula is seen to be a generic consequence of critical rotation. We find that if the pressure in such stars is sufficiently dominated by radiation, an equatorial ...

  6. Quantum heat engine with continuum working medium

    OpenAIRE

    Li, S.; Wang, H.; Sun, Y. D.; Yi, X. X.

    2006-01-01

    We introduce a new quantum heat engine, in which the working medium is a quantum system with a discrete level and a continuum. Net work done by this engine is calculated and discussed. The results show that this quantum heat engine behaves like the two-level quantum heat engine in both the high-temperature and the low-temperature limits, but it operates differently in temperatures between them. The efficiency of this quantum heat engine is also presented and discussed.

  7. Sensitivity filtering from a continuum mechanics perspective

    DEFF Research Database (Denmark)

    Sigmund, Ole; Maute, Kurt

    2012-01-01

    In topology optimization filtering is a popular approach for preventing numerical instabilities. This short note shows that the well-known sensitivity filtering technique, that prevents checkerboards and ensures mesh-independent designs in density-based topology optimization, is equivalent to min...... to minimizing compliance for nonlocal elasticity problems known from continuum mechanics. Hence, the note resolves the long-standing quest for finding an explanation and physical motivation for the sensitivity filter....

  8. Continuum mechanics the birthplace of mathematical models

    CERN Document Server

    Allen, Myron B

    2015-01-01

    Continuum mechanics is a standard course in many graduate programs in engineering and applied mathematics as it provides the foundations for the various differential equations and mathematical models that are encountered in fluid mechanics, solid mechanics, and heat transfer.  This book successfully makes the topic more accessible to advanced undergraduate mathematics majors by aligning the mathematical notation and language with related courses in multivariable calculus, linear algebra, and differential equations; making connections with other areas of applied mathematics where parial differe

  9. On the Continuum of Eating Disorders

    OpenAIRE

    Hawkins, Lana Lee Munro

    2007-01-01

    Theorists and researchers have long debated as to whether the differences between subthreshold levels of eating disturbances and diagnosable eating disorders are a difference of degree (the continuum hypothesis) or a difference of kind (the discontinuity hypothesis). The present study investigated the relationship between level of eating disordered behaviour and the psychopathology associated with, and thought by some to be prodromal factors in, the development of clinically diagnosable eatin...

  10. The thermal infrared continuum in solar flares

    Science.gov (United States)

    Fletcher, Lyndsay; Simoes, Paulo; Kerr, Graham Stewart; Hudson, Hugh S.; Gimenez de Castro, C. Guillermo; Penn, Matthew J.

    2017-08-01

    Observations of the Sun with the Atacama Large Millimeter Array have now started, and the thermal infrared will regularly be accessible from the NSF’s Daniel K. Inouye Solar Telescope. Motivated by the prospect of these new observations, and by recent flare detections in the mid infrared, we set out here to model and understand the source of the infrared continuum in flares, and to explore its diagnostic capability for the physical conditions in the flare atmosphere. We use the 1D radiation hydrodynamics code RADYN to calculate mid-infrared continuum emission from model atmospheres undergoing sudden deposition of energy by non-thermal electrons. We identify and characterise the main continuum thermal emission processes relevant to flare intensity enhancement in the mid- to far-infrared (2-200 micron) spectral range as free-free emission on neutrals and ions. We find that the infrared intensity evolution tracks the energy input to within a second, albeit with a lingering intensity enhancement, and provides a very direct indication of the evolution of the atmospheric ionization. The prediction of highly impulsive emission means that, on these timescales, the atmospheric hydrodynamics need not be considered in analysing the mid-IR signatures.

  11. Lattice Boltzmann algorithm for continuum multicomponent flow

    Science.gov (United States)

    Halliday, I.; Hollis, A. P.; Care, C. M.

    2007-08-01

    We present a multicomponent lattice Boltzmann simulation for continuum fluid mechanics, paying particular attention to the component segregation part of the underlying algorithm. In the principal result of this paper, the dynamics of a component index, or phase field, is obtained for a segregation method after U. D’Ortona [Phys. Rev. E 51, 3718 (1995)], due to Latva-Kokko and Rothman [Phys. Rev. E 71 056702 (2005)]. The said dynamics accord with a simulation designed to address multicomponent flow in the continuum approximation and underwrite improved simulation performance in two main ways: (i) by reducing the interfacial microcurrent activity considerably and (ii) by facilitating simulational access to regimes of flow with a low capillary number and drop Reynolds number [I. Halliday, R. Law, C. M. Care, and A. Hollis, Phys. Rev. E 73, 056708 (2006)]. The component segregation method studied, used in conjunction with Lishchuk’s method [S. V. Lishchuk, C. M. Care, and I. Halliday, Phys. Rev. E 67, 036701 (2003)], produces an interface, which is distributed in terms of its component index; however, the hydrodynamic boundary conditions which emerge are shown to support the notion of a sharp, unstructured, continuum interface.

  12. Coupling discrete and continuum concentration particle models for multiscale and hybrid molecular-continuum simulations

    Science.gov (United States)

    Petsev, Nikolai D.; Leal, L. Gary; Shell, M. Scott

    2017-12-01

    Hybrid molecular-continuum simulation techniques afford a number of advantages for problems in the rapidly burgeoning area of nanoscale engineering and technology, though they are typically quite complex to implement and limited to single-component fluid systems. We describe an approach for modeling multicomponent hydrodynamic problems spanning multiple length scales when using particle-based descriptions for both the finely resolved (e.g., molecular dynamics) and coarse-grained (e.g., continuum) subregions within an overall simulation domain. This technique is based on the multiscale methodology previously developed for mesoscale binary fluids [N. D. Petsev, L. G. Leal, and M. S. Shell, J. Chem. Phys. 144, 084115 (2016)], simulated using a particle-based continuum method known as smoothed dissipative particle dynamics. An important application of this approach is the ability to perform coupled molecular dynamics (MD) and continuum modeling of molecularly miscible binary mixtures. In order to validate this technique, we investigate multicomponent hybrid MD-continuum simulations at equilibrium, as well as non-equilibrium cases featuring concentration gradients.

  13. Forest Management.

    Science.gov (United States)

    Weicherding, Patrick J.; And Others

    This bulletin deals with forest management and provides an overview of forestry for the non-professional. The bulletin is divided into six sections: (1) What Is Forestry Management?; (2) How Is the Forest Measured?; (3) What Is Forest Protection?; (4) How Is the Forest Harvested?; (5) What Is Forest Regeneration?; and (6) What Is Forest…

  14. Non-classical continuum mechanics a dictionary

    CERN Document Server

    Maugin, Gérard A

    2017-01-01

    This dictionary offers clear and reliable explanations of over 100 keywords covering the entire field of non-classical continuum mechanics and generalized mechanics, including the theory of elasticity, heat conduction, thermodynamic and electromagnetic continua, as well as applied mathematics. Every entry includes the historical background and the underlying theory, basic equations and typical applications. The reference list for each entry provides a link to the original articles and the most important in-depth theoretical works. Last but not least, every entry is followed by a cross-reference to other related subject entries in the dictionary.

  15. Set theory and the continuum hypothesis

    CERN Document Server

    Cohen, Paul J

    2008-01-01

    This exploration of a notorious mathematical problem is the work of the man who discovered the solution. The independence of the continuum hypothesis is the focus of this study by Paul J. Cohen. It presents not only an accessible technical explanation of the author's landmark proof but also a fine introduction to mathematical logic. An emeritus professor of mathematics at Stanford University, Dr. Cohen won two of the most prestigious awards in mathematics: in 1964, he was awarded the American Mathematical Society's Bôcher Prize for analysis; and in 1966, he received the Fields Medal for Logic.

  16. Continuum modeling an approach through practical examples

    CERN Document Server

    Muntean, Adrian

    2015-01-01

    This book develops continuum modeling skills and approaches the topic from three sides: (1) derivation of global integral laws together with the associated local differential equations, (2) design of constitutive laws and (3) modeling boundary processes. The focus of this presentation lies on many practical examples covering aspects such as coupled flow, diffusion and reaction in porous media or microwave heating of a pizza, as well as traffic issues in bacterial colonies and energy harvesting from geothermal wells. The target audience comprises primarily graduate students in pure and applied mathematics as well as working practitioners in engineering who are faced by nonstandard rheological topics like those typically arising in the food industry.

  17. Histidine in Continuum Electrostatics Protonation State Calculations

    Science.gov (United States)

    Couch, Vernon; Stuchebruckhov, Alexei

    2014-01-01

    A modification to the standard continuum electrostatics approach to calculate protein pKas which allows for the decoupling of histidine tautomers within a two state model is presented. Histidine with four intrinsically coupled protonation states cannot be easily incorporated into a two state formalism because the interaction between the two protonatable sites of the imidazole ring is not purely electrostatic. The presented treatment, based on a single approximation of the interrelation between histidine’s charge states, allows for a natural separation of the two protonatable sites associated with the imidazole ring as well as the inclusion of all protonation states within the calculation. PMID:22072521

  18. Lyman Continuum Leakage in the Local Universe

    Science.gov (United States)

    Leitherer, Claus; Hernandez, Svea; Lee, Janice; Oey, Sally

    2015-08-01

    Star-forming galaxies are viable candidates for providing the ionizing photon supply accounting for the reionization of the early universe. However, direct determination of the fraction of ionizing photons that can escape the optically thick galaxy ISM is challenging. I will discuss Lyman continuum observations of a sample of massive young star clusters in local galaxies which take advantage of a new capability of HST's Cosmic Origins Spectrograph. The derived photon leakages are compared to values found at high redshift and discussed in the context of cosmological models.

  19. Continuum description of avalanches in granular media.

    Energy Technology Data Exchange (ETDEWEB)

    Aranson, I. S.; Tsimring, L. S.

    2000-12-05

    A continuum theory of partially fluidized granular flows is proposed. The theory is based on a combination of the mass and momentum conservation equations with the order parameter equation which describes the transition between flowing and static components of the granular system. We apply this model to the dynamics of avalanches in chutes. The theory provides a quantitative description of recent observations of granular flows on rough inclined planes (Daerr and Douady 1999): layer bistability, and the transition from triangular avalanches propagating downhill at small inclination angles to balloon-shaped avalanches also propagating uphill for larger angles.

  20. Non-coherent continuum scattering as a line polarization mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Del Pino Alemán, T.; Manso Sainz, R.; Trujillo Bueno, J., E-mail: tanausu@iac.es, E-mail: rsainz@iac.es, E-mail: jtb@iac.es [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2014-03-20

    Line scattering polarization can be strongly affected by Rayleigh scattering at neutral hydrogen and Thomson scattering at free electrons. Often a depolarization of the continuum results, but the Doppler redistribution produced by the continuum scatterers, which are light (hence, fast), induces more complex interactions between the polarization in spectral lines and in the continuum. Here we formulate and solve the radiative transfer problem of scattering line polarization with non-coherent continuum scattering consistently. The problem is formulated within the spherical tensor representation of atomic and light polarization. The numerical method of solution is a generalization of the Accelerated Lambda Iteration that is applied to both the atomic system and the radiation field. We show that the redistribution of the spectral line radiation due to the non-coherence of the continuum scattering may modify the shape of the emergent fractional linear polarization patterns significantly, even yielding polarization signals above the continuum level in intrinsically unpolarizable lines.

  1. Continuum deformation of multi-agent systems

    CERN Document Server

    Rastgoftar, Hossein

    2016-01-01

    This monograph presents new algorithms for formation control of multi-agent systems (MAS) based on principles of continuum mechanics. Beginning with an overview of traditional methods, the author then introduces an innovative new approach whereby agents of an MAS are considered as particles in a continuum evolving in ℝn whose desired configuration is required to satisfy an admissible deformation function. The necessary theory and its validation on a mobile-agent-based swarm test bed are considered for two primary tasks: homogeneous transformation of the MAS and deployment of a random distribution of agents on a desired configuration. The framework for this model is based on homogeneous transformations for the evolution of an MAS under no inter-agent communication, local inter-agent communication, and intelligent perception by agents. Different communication protocols for MAS evolution, the robustness of tracking of a desired motion by an MAS evolving in ℝn, and the effect of communication delays in an MAS...

  2. Continuum robot arms inspired by cephalopods

    Science.gov (United States)

    Walker, Ian D.; Dawson, Darren M.; Flash, Tamar; Grasso, Frank W.; Hanlon, Roger T.; Hochner, Binyamin; Kier, William M.; Pagano, Christopher C.; Rahn, Christopher D.; Zhang, Qiming M.

    2005-05-01

    In this paper, we describe our recent results in the development of a new class of soft, continuous backbone ("continuum") robot manipulators. Our work is strongly motivated by the dexterous appendages found in cephalopods, particularly the arms and suckers of octopus, and the arms and tentacles of squid. Our ongoing investigation of these animals reveals interesting and unexpected functional aspects of their structure and behavior. The arrangement and dynamic operation of muscles and connective tissue observed in the arms of a variety of octopus species motivate the underlying design approach for our soft manipulators. These artificial manipulators feature biomimetic actuators, including artificial muscles based on both electro-active polymers (EAP) and pneumatic (McKibben) muscles. They feature a "clean" continuous backbone design, redundant degrees of freedom, and exhibit significant compliance that provides novel operational capacities during environmental interaction and object manipulation. The unusual compliance and redundant degrees of freedom provide strong potential for application to delicate tasks in cluttered and/or unstructured environments. Our aim is to endow these compliant robotic mechanisms with the diverse and dexterous grasping behavior observed in octopuses. To this end, we are conducting fundamental research into the manipulation tactics, sensory biology, and neural control of octopuses. This work in turn leads to novel approaches to motion planning and operator interfaces for the robots. The paper describes the above efforts, along with the results of our development of a series of continuum tentacle-like robots, demonstrating the unique abilities of biologically-inspired design.

  3. Forest hydrology

    Science.gov (United States)

    Ge Sun; Devendra Amatya; Steve McNulty

    2016-01-01

    Forest hydrology studies the distribution, storage, movement, and quality of water and the hydrological processes in forest-dominated ecosystems. Forest hydrological science is regarded as the foundation of modern integrated water¬shed management. This chapter provides an overview of the history of forest hydrology and basic principles of this unique branch of...

  4. Forest soils

    Science.gov (United States)

    Charles H. (Hobie) Perry; Michael C. Amacher

    2009-01-01

    Productive soils are the foundation of sustainable forests throughout the United States. Forest soils are generally subjected to fewer disturbances than agricultural soils, particularly those that are tilled, so forest soils tend to have better preserved A-horizons than agricultural soils. Another major contrast between forest and agricultural soils is the addition of...

  5. Forest Management

    Science.gov (United States)

    S. Hummel; K. L. O' Hara

    2008-01-01

    Global variation in forests and in human cultures means that a single method for managing forests is not possible. However, forest management everywhere shares some common principles because it is rooted in physical and biological sciences like chemistry and genetics. Ecological forest management is an approach that combines an understanding of universal processes with...

  6. Broadly continuously tunable slot waveguide quantum cascade lasers based on a continuum-to-continuum active region design

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Bo; Zeng, Yong Quan; Liang, Guozhen; Hu, Xiao Nan; Rodriguez, Etienne [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Tao, Jin [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); CDPT, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore); Wang, Qi Jie, E-mail: qjwang@ntu.edu.sg [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CDPT, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore)

    2015-09-14

    We report our progress in the development of broadly tunable single-mode slot waveguide quantum cascade lasers based on a continuum-to-continuum active region design. The electroluminescence spectrum of the continuum-to-continuum active region design has a full width at half maximum of 440 cm{sup −1} at center wavelength ∼10 μm at room temperature (300 K). Devices using the optimized slot waveguide structure and the continuum-to-continuum design can be tuned continuously with a lasing emission over 42 cm{sup −1}, from 9.74 to 10.16 μm, at room temperature by using only current tuning scheme, together with a side mode suppression ratio of above 15 dB within the whole tuning range.

  7. A continuum theory of edge dislocations

    Science.gov (United States)

    Berdichevsky, V. L.

    2017-09-01

    Continuum theory of dislocation aims to describe the behavior of large ensembles of dislocations. This task is far from completion, and, most likely, does not have a ;universal solution;, which is applicable to any dislocation ensemble. In this regards it is important to have guiding lines set by benchmark cases, where the transition from a discrete set of dislocations to a continuum description is made rigorously. Two such cases have been considered recently: equilibrium of dislocation walls and screw dislocations in beams. In this paper one more case is studied, equilibrium of a large set of 2D edge dislocations placed randomly in a 2D bounded region. The major characteristic of interest is energy of dislocation ensemble, because it determines the structure of continuum equations. The homogenized energy functional is obtained for the periodic dislocation ensembles with a random contents of the periodic cell. Parameters of the periodic structure can change slowly on distances of order of the size of periodic cells. The energy functional is obtained by the variational-asymptotic method. Equilibrium positions are local minima of energy. It is confirmed the earlier assertion that energy density of the system is the sum of elastic energy of averaged elastic strains and microstructure energy, which is elastic energy of the neutralized dislocation system, i.e. the dislocation system placed in a constant dislocation density field making the averaged dislocation density zero. The computation of energy is reduced to solution of a variational cell problem. This problem is solved analytically. The solution is used to investigate stability of simple dislocation arrays, i.e. arrays with one dislocation in the periodic cell. The relations obtained yield two outcomes: First, there is a state parameter of the system, dislocation polarization; averaged stresses affect only dislocation polarization and cannot change other characteristics of the system. Second, the structure of

  8. Forest rights

    DEFF Research Database (Denmark)

    Balooni, Kulbhushan; Lund, Jens Friis

    2014-01-01

    One of the proposed strategies for implementation of reducing emissions from deforestation and forest degradation plus (REDD+) is to incentivize conservation of forests managed by communities under decentralized forest management. Yet, we argue that this is a challenging road to REDD+ because......+ transactions costs. Third, beyond the “conservation islands” represented by forests under decentralized management, processes of deforestation and forest degradation continue. Given these challenges, we argue that REDD+ efforts through decentralized forestry should be redirected from incentivizing further...

  9. Variational continuum multiphase poroelasticity theory and applications

    CERN Document Server

    Serpieri, Roberto

    2017-01-01

    This book collects the theoretical derivation of a recently presented general variational macroscopic continuum theory of multiphase poroelasticity (VMTPM), together with its applications to consolidation and stress partitioning problems of interest in several applicative engineering contexts, such as in geomechanics and biomechanics. The theory is derived based on a purely-variational deduction, rooted in the least-Action principle, by considering a minimal set of kinematic descriptors. The treatment herein considered keeps a specific focus on the derivation of most general medium-independent governing equations. It is shown that VMTPM recovers paradigms of consolidated use in multiphase poroelasticity such as Terzaghi's stress partitioning principle and Biot's equations for wave propagation. In particular, the variational treatment permits the derivation of a general medium-independent stress partitioning law, and the proposed variational theory predicts that the external stress, the fluid pressure, and the...

  10. Embodiment design of soft continuum robots

    Directory of Open Access Journals (Sweden)

    Rongjie Kang

    2016-04-01

    Full Text Available This article presents the results of a multidisciplinary project where mechatronic engineers worked alongside biologists to develop a soft robotic arm that captures key features of octopus anatomy and neurophysiology. The concept of embodiment (the dynamic coupling between sensory-motor control, anatomy, materials and environment that allows for the animal to achieve adaptive behaviours is used as a starting point for the design process but tempered by current engineering technologies and approaches. In this article, the embodied design requirements are first discussed from a robotic viewpoint by taking into account real-life engineering limitations; then, the motor control schemes inspired by octopus nervous system are investigated. Finally, the mechanical and control design of a prototype is presented that appropriately blends bio-inspiration and engineering limitations. Simulated and experimental results show that the developed continuum robotic arm is able to reproduce octopus-like motions for bending, reaching and grasping.

  11. Atomic size effects in continuum modeling

    Science.gov (United States)

    Ratsch, C.; Kang, M.; Caflisch, R. E.

    2001-08-01

    Continuum modeling of many physical systems typically assumes that the spatial extent of an atom is small compared to the quantities of interest and can therefore be neglected. We show that this is valid only asymptotically. For many applications of practical interest, the spatial extent of a discrete atom cannot be neglected. We have developed a model for the description of epitaxial growth based on the levelset method, and find that we can accurately predict quantities such as the island densities, if we implement boundary conditions in a region with atomic width, rather than just on a line without any spatial extent. Only in the limit of very large islands and island spacings can this be neglected.

  12. Continuum Reverberation Mapping of AGN Accretion Disks

    Directory of Open Access Journals (Sweden)

    Michael M. Fausnaugh

    2017-12-01

    Full Text Available We show recent detections of inter-band continuum lags in three AGN (NGC 5548, NGC 2617, and MCG+08-11-011, which provide new constraints on the temperature profiles and absolute sizes of the accretion disks. We find lags larger than would be predicted for standard geometrically thin, optically thick accretion disks by factors of 2.3–3.3. For NGC 5548, the data span UV through optical/near-IR wavelengths, and we are able to discern a steeper temperature profile than the T ~ R−3/4 expected for a standard thin disk. Using a physical model, we are also able to estimate the inclinations of the disks for two objects. These results are similar to those found from gravitational microlensing of strongly lensed quasars, and provide a complementary approach for investigating the accretion disk structure in local, low luminosity AGN.

  13. A Threshold Continuum for Aeolian Sand Transport

    Science.gov (United States)

    Swann, C.; Ewing, R. C.; Sherman, D. J.

    2015-12-01

    The threshold of motion for aeolian sand transport marks the initial entrainment of sand particles by the force of the wind. This is typically defined and modeled as a singular wind speed for a given grain size and is based on field and laboratory experimental data. However, the definition of threshold varies significantly between these empirical models, largely because the definition is based on visual-observations of initial grain movement. For example, in his seminal experiments, Bagnold defined threshold of motion when he observed that 100% of the bed was in motion. Others have used 50% and lesser values. Differences in threshold models, in turn, result is large errors in predicting the fluxes associated with sand and dust transport. Here we use a wind tunnel and novel sediment trap to capture the fractions of sand in creep, reptation and saltation at Earth and Mars pressures and show that the threshold of motion for aeolian sand transport is best defined as a continuum in which grains progress through stages defined by the proportion of grains in creep and saltation. We propose the use of scale dependent thresholds modeled by distinct probability distribution functions that differentiate the threshold based on micro to macro scale applications. For example, a geologic timescale application corresponds to a threshold when 100% of the bed in motion whereas a sub-second application corresponds to a threshold when a single particle is set in motion. We provide quantitative measurements (number and mode of particle movement) corresponding to visual observations, percent of bed in motion and degrees of transport intermittency for Earth and Mars. Understanding transport as a continuum provides a basis for revaluating sand transport thresholds on Earth, Mars and Titan.

  14. Continuum Damage Mechanics A Continuum Mechanics Approach to the Analysis of Damage and Fracture

    CERN Document Server

    Murakami, Sumio

    2012-01-01

    Recent developments in engineering and technology have brought about serious and enlarged demands for reliability, safety and economy in wide range of fields such as aeronautics, nuclear engineering, civil and structural engineering, automotive and production industry.  This, in turn, has caused more interest in continuum damage mechanics and its engineering applications.   This book aims to give a concise overview of the current state of damage mechanics, and then to show the fascinating possibility of this promising branch of mechanics, and to provide researchers, engineers and graduate students with an intelligible and self-contained textbook.   The book consists of two parts and an appendix.  Part I  is concerned with the foundation of continuum damage mechanics.  Basic concepts of material damage and the mechanical representation of damage state of various kinds are described in Chapters 1 and 2.  In Chapters 3-5, irreversible thermodynamics, thermodynamic constitutive theory and its application ...

  15. Hybrid continuum-atomistic approach to model electrokinetics in nanofluidics

    Energy Technology Data Exchange (ETDEWEB)

    Amani, Ehsan, E-mail: eamani@aut.ac.ir; Movahed, Saeid, E-mail: smovahed@aut.ac.ir

    2016-06-07

    In this study, for the first time, a hybrid continuum-atomistic based model is proposed for electrokinetics, electroosmosis and electrophoresis, through nanochannels. Although continuum based methods are accurate enough to model fluid flow and electric potential in nanofluidics (in dimensions larger than 4 nm), ionic concentration is too low in nanochannels for the continuum assumption to be valid. On the other hand, the non-continuum based approaches are too time-consuming and therefore is limited to simple geometries, in practice. Here, to propose an efficient hybrid continuum-atomistic method of modelling the electrokinetics in nanochannels; the fluid flow and electric potential are computed based on continuum hypothesis coupled with an atomistic Lagrangian approach for the ionic transport. The results of the model are compared to and validated by the results of the molecular dynamics technique for a couple of case studies. Then, the influences of bulk ionic concentration, external electric field, size of nanochannel, and surface electric charge on the electrokinetic flow and ionic mass transfer are investigated, carefully. The hybrid continuum-atomistic method is a promising approach to model more complicated geometries and investigate more details of the electrokinetics in nanofluidics. - Highlights: • A hybrid continuum-atomistic model is proposed for electrokinetics in nanochannels. • The model is validated by molecular dynamics. • This is a promising approach to model more complicated geometries and physics.

  16. The urban watershed continuum: evolving spatial and temporal dimensions

    Science.gov (United States)

    Sujay S. Kaushal; Kenneth T. Belt

    2012-01-01

    Urban ecosystems are constantly evolving, and they are expected to change in both space and time with active management or degradation. An urban watershed continuum framework recognizes a continuum of engineered and natural hydrologic flowpaths that expands hydrologic networks in ways that are seldom considered. It recognizes that the nature of hydrologic connectivity...

  17. Continuum Thinking and the Contexts of Personal Information Management

    Science.gov (United States)

    Huvila, Isto; Eriksen, Jon; Häusner, Eva-Maria; Jansson, Ina-Maria

    2014-01-01

    Introduction: Recent personal information management literature has underlined the significance of the contextuality of personal information and its use. The present article discusses the applicability of the records continuum model and its generalisation, continuum thinking, as a theoretical framework for explicating the overlap and evolution of…

  18. Continuum of Counseling Goals: A Framework for Differentiating Counseling Strategies.

    Science.gov (United States)

    Bruce, Paul

    1984-01-01

    Presents counseling goals in a developmental continuum similar in concept to Maslow's hierarchy of needs. Discusses ego development goals, socialization goals, developmental goals, self-esteem goals, and self-realization goals and describes characteristics and implications of the continuum. (JAC)

  19. Points-Based Safe Path Planning of Continuum Robots

    Directory of Open Access Journals (Sweden)

    Khuram Shahzad

    2015-07-01

    Full Text Available Continuum robots exhibit great potential in a number of challenging applications where traditional rigid link robots pose certain limitations, e.g., working in unstructured environments. In order to enable the usage of continuum robots in safety-critical applications, such as surgery and nuclear decontamination, it is extremely important to ensure a safe path for the robot's movement. Existing algorithms for continuum robot path planning have certain limitations that need to be addressed. These include the fact that none of the algorithms provide safety assurance parameters and control for path planning. They are computationally expensive, applicable to a specific type of continuum robots, and mostly they do not incorporate design and kinematics constraints. In this paper, we propose a points-based path planning (PoPP algorithm for continuum robots that computes the path by imposing safety constraints and improves upon the limitations of existing approaches. In the algorithm, we exploit the constant curvature-bending property of continuum robots in their path planning process. The algorithm is computationally efficient and provides a good tradeoff between accuracy and efficiency that can be implemented to enable the safety-critical application of continuum robots. This algorithm also provides information regarding path volume and flexibility in movement. Simulation results confirm that the algorithm possesses promising potential for all types of continuum robots (following the constant curvature-bending property. We believe that this effectively balances the desired safety and efficiency requirements.

  20. Teaching Continuum Mechanics in a Mechanical Engineering Program

    Science.gov (United States)

    Liu, Yucheng

    2011-01-01

    This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

  1. A soil burn severity index for understanding soil-fire relations in tropical forests [Chinese version

    Science.gov (United States)

    Theresa B. Jain; William A. Gould; Russell T. Graham; David S. Pilliod; Leigh B. Lentile; Grizelle Gonzalez

    2008-01-01

    Methods for evaluating the impact of fires within tropical forests are needed as fires become more frequent and human populations and demands on forests increase. Short- and long-term fire effects on soils are determined by the prefire, fire, and postfire environments. We placed these components within a fire-disturbance continuum to guide our literature synthesis and...

  2. Forest Resources

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-06-01

    Forest biomass is an abundant biomass feedstock that complements the conventional forest use of wood for paper and wood materials. It may be utilized for bioenergy production, such as heat and electricity, as well as for biofuels and a variety of bioproducts, such as industrial chemicals, textiles, and other renewable materials. The resources within the 2016 Billion-Ton Report include primary forest resources, which are taken directly from timberland-only forests, removed from the land, and taken to the roadside.

  3. Estimating foliar biochemistry from hyperspectral data in mixed forest canopy

    DEFF Research Database (Denmark)

    Huber Gharib, Silvia; Kneubühler, Mathias; Psomas, Achilleas

    2008-01-01

    data to estimate the foliar concentration of nitrogen, carbon and water in three mixed forest canopies in Switzerland. With multiple linear regression models, continuum-removed and normalized HyMap spectra were related to foliar biochemistry on an individual tree level. The six spectral wavebands used...

  4. A robust, coupled approach for atomistic-continuum simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, Sylvie; Webb, Edmund Blackburn, III (Sandia National Laboratories, Albuquerque, NM); Wagner, Gregory John; Klein, Patrick A.; Jones, Reese E.; Zimmerman, Jonathan A.; Bammann, Douglas J.; Hoyt, Jeffrey John (Sandia National Laboratories, Albuquerque, NM); Kimmer, Christopher J.

    2004-09-01

    This report is a collection of documents written by the group members of the Engineering Sciences Research Foundation (ESRF), Laboratory Directed Research and Development (LDRD) project titled 'A Robust, Coupled Approach to Atomistic-Continuum Simulation'. Presented in this document is the development of a formulation for performing quasistatic, coupled, atomistic-continuum simulation that includes cross terms in the equilibrium equations that arise due to kinematic coupling and corrections used for the calculation of system potential energy to account for continuum elements that overlap regions containing atomic bonds, evaluations of thermo-mechanical continuum quantities calculated within atomistic simulations including measures of stress, temperature and heat flux, calculation used to determine the appropriate spatial and time averaging necessary to enable these atomistically-defined expressions to have the same physical meaning as their continuum counterparts, and a formulation to quantify a continuum 'temperature field', the first step towards constructing a coupled atomistic-continuum approach capable of finite temperature and dynamic analyses.

  5. Hybrid continuum-atomistic approach to model electrokinetics in nanofluidics.

    Science.gov (United States)

    Amani, Ehsan; Movahed, Saeid

    2016-06-07

    In this study, for the first time, a hybrid continuum-atomistic based model is proposed for electrokinetics, electroosmosis and electrophoresis, through nanochannels. Although continuum based methods are accurate enough to model fluid flow and electric potential in nanofluidics (in dimensions larger than 4 nm), ionic concentration is too low in nanochannels for the continuum assumption to be valid. On the other hand, the non-continuum based approaches are too time-consuming and therefore is limited to simple geometries, in practice. Here, to propose an efficient hybrid continuum-atomistic method of modelling the electrokinetics in nanochannels; the fluid flow and electric potential are computed based on continuum hypothesis coupled with an atomistic Lagrangian approach for the ionic transport. The results of the model are compared to and validated by the results of the molecular dynamics technique for a couple of case studies. Then, the influences of bulk ionic concentration, external electric field, size of nanochannel, and surface electric charge on the electrokinetic flow and ionic mass transfer are investigated, carefully. The hybrid continuum-atomistic method is a promising approach to model more complicated geometries and investigate more details of the electrokinetics in nanofluidics. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Equivalent-Continuum Modeling With Application to Carbon Nanotubes

    Science.gov (United States)

    Odegard, Gregory M.; Gates, Thomas S.; Nicholson, Lee M.; Wise, Kristopher E.

    2002-01-01

    A method has been proposed for developing structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with equivalent-continuum models. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As important examples with direct application to the development and characterization of single-walled carbon nanotubes and the design of nanotube-based devices, the modeling technique has been applied to determine the effective-continuum geometry and bending rigidity of a graphene sheet. A representative volume element of the chemical structure of graphene has been substituted with equivalent-truss and equivalent continuum models. As a result, an effective thickness of the continuum model has been determined. This effective thickness has been shown to be significantly larger than the interatomic spacing of graphite. The effective thickness has been shown to be significantly larger than the inter-planar spacing of graphite. The effective bending rigidity of the equivalent-continuum model of a graphene sheet was determined by equating the vibrational potential energy of the molecular model of a graphene sheet subjected to cylindrical bending with the strain energy of an equivalent continuum plate subjected to cylindrical bending.

  7. Multigrid treatment of implicit continuum diffusion

    Science.gov (United States)

    Francisquez, Manaure; Zhu, Ben; Rogers, Barrett

    2017-10-01

    Implicit treatment of diffusive terms of various differential orders common in continuum mechanics modeling, such as computational fluid dynamics, is investigated with spectral and multigrid algorithms in non-periodic 2D domains. In doubly periodic time dependent problems these terms can be efficiently and implicitly handled by spectral methods, but in non-periodic systems solved with distributed memory parallel computing and 2D domain decomposition, this efficiency is lost for large numbers of processors. We built and present here a multigrid algorithm for these types of problems which outperforms a spectral solution that employs the highly optimized FFTW library. This multigrid algorithm is not only suitable for high performance computing but may also be able to efficiently treat implicit diffusion of arbitrary order by introducing auxiliary equations of lower order. We test these solvers for fourth and sixth order diffusion with idealized harmonic test functions as well as a turbulent 2D magnetohydrodynamic simulation. It is also shown that an anisotropic operator without cross-terms can improve model accuracy and speed, and we examine the impact that the various diffusion operators have on the energy, the enstrophy, and the qualitative aspect of a simulation. This work was supported by DOE-SC-0010508. This research used resources of the National Energy Research Scientific Computing Center (NERSC).

  8. Diagnostic Reasoning across the Medical Education Continuum

    Directory of Open Access Journals (Sweden)

    C. Scott Smith

    2014-07-01

    Full Text Available We aimed to study linguistic and non-linguistic elements of diagnostic reasoning across the continuum of medical education. We performed semi-structured interviews of premedical students, first year medical students, third year medical students, second year internal medicine residents, and experienced faculty (ten each as they diagnosed three common causes of dyspnea. A second observer recorded emotional tone. All interviews were digitally recorded and blinded transcripts were created. Propositional analysis and concept mapping were performed. Grounded theory was used to identify salient categories and transcripts were scored with these categories. Transcripts were then unblinded. Systematic differences in propositional structure, number of concept connections, distribution of grounded theory categories, episodic and semantic memories, and emotional tone were identified. Summary concept maps were created and grounded theory concepts were explored for each learning level. We identified three major findings: (1 The “apprentice effect” in novices (high stress and low narrative competence; (2 logistic concept growth in intermediates; and (3 a cognitive state transition (between analytical and intuitive approaches in experts. These findings warrant further study and comparison.

  9. Elementary Continuum Mechanics for Everyone - And Some More

    DEFF Research Database (Denmark)

    Byskov, Esben

    Quite trivially, Continuum mechanics per se deals with the description of deformations of three-dimensional continua i.e. models whose properties are independent of scale in that the continuum does not possess a structure. Thus, continuum mechanics does not try to model the atomic structure...... of the involved materials- perhaps not even the crystalline or spongy, or lumpy structure- but offers a "smeared-out" version of the real world. Also, the desired description depends very much on the needs of the dicipline in question....

  10. Elementary Continuum Mechanics for Everyone - and Some More

    DEFF Research Database (Denmark)

    Byskov, Esben

    Quite trivially, Continuum mechanics per se deals with the description of deformations of three-dimensional continua i.e. models whose properties are independent of scale in that the continuum does not possess a structure. Thus, continuum mechanics does not try to model the atomic structure...... of the involved materials- perhaps not even the crystalline or spongy, or lumpy structure- but offers a "smeared-out" version of the real world. Also, the desired description depends very much on the needs of the discipline in question....

  11. Continuum simulations of water flow past fullerene molecules

    DEFF Research Database (Denmark)

    Popadic, A.; Praprotnik, M.; Koumoutsakos, P.

    2015-01-01

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest...... as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently by continuum flow...

  12. SEACAS Theory Manuals: Part II. Nonlinear Continuum Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Attaway, S.W.; Laursen, T.A.; Zadoks, R.I.

    1998-09-01

    This report summarizes the key continuum mechanics concepts required for the systematic prescription and numerical solution of finite deformation solid mechanics problems. Topics surveyed include measures of deformation appropriate for media undergoing large deformations, stress measures appropriate for such problems, balance laws and their role in nonlinear continuum mechanics, the role of frame indifference in description of large deformation response, and the extension of these theories to encompass two dimensional idealizations, structural idealizations, and rigid body behavior. There are three companion reports that describe the problem formulation, constitutive modeling, and finite element technology for nonlinear continuum mechanics systems.

  13. Microstructural and continuum evolution modeling of sintering.

    Energy Technology Data Exchange (ETDEWEB)

    Braginsky, Michael V.; Olevsky, Eugene A. (San Diego State University, San Diego, CA); Johnson, D. Lynn (Northwest University, Evanston, IL); Tikare, Veena; Garino, Terry J.; Arguello, Jose Guadalupe, Jr.

    2003-12-01

    All ceramics and powder metals, including the ceramics components that Sandia uses in critical weapons components such as PZT voltage bars and current stacks, multi-layer ceramic MET's, ahmindmolybdenum & alumina cermets, and ZnO varistors, are manufactured by sintering. Sintering is a critical, possibly the most important, processing step during manufacturing of ceramics. The microstructural evolution, the macroscopic shrinkage, and shape distortions during sintering will control the engineering performance of the resulting ceramic component. Yet, modeling and prediction of sintering behavior is in its infancy, lagging far behind the other manufacturing models, such as powder synthesis and powder compaction models, and behind models that predict engineering properties and reliability. In this project, we developed a model that was capable of simulating microstructural evolution during sintering, providing constitutive equations for macroscale simulation of shrinkage and distortion during sintering. And we developed macroscale sintering simulation capability in JAS3D. The mesoscale model can simulate microstructural evolution in a complex powder compact of hundreds or even thousands of particles of arbitrary shape and size by 1. curvature-driven grain growth, 2. pore migration and coalescence by surface diffusion, 3. vacancy formation, grain boundary diffusion and annihilation. This model was validated by comparing predictions of the simulation to analytical predictions for simple geometries. The model was then used to simulate sintering in complex powder compacts. Sintering stress and materials viscous module were obtained from the simulations. These constitutive equations were then used by macroscopic simulations for simulating shrinkage and shape changes in FEM simulations. The continuum theory of sintering embodied in the constitutive description of Skorohod and Olevsky was combined with results from microstructure evolution simulations to model shrinkage

  14. The Hurricane-Flood-Landslide Continuum

    Science.gov (United States)

    Negri, Andrew J.; Burkardt, Nina; Golden, Joseph H.; Halverson, Jeffrey B.; Huffman, George J.; Larsen, Matthew C.; McGinley, John A.; Updike, Randall G.; Verdin, James P.; Wieczorek, Gerald F.

    2005-01-01

    In August 2004, representatives from NOAA, NASA, the USGS, and other government agencies convened in San Juan, Puerto Rim for a workshop to discuss a proposed research project called the Hurricane-Flood-Landslide Continuum (HFLC). The essence of the HFLC is to develop and integrate tools across disciplines to enable the issuance of regional guidance products for floods and landslides associated with major tropical rain systems, with sufficient lead time that local emergency managers can protect vulnerable populations and infrastructure. All three lead agencies are independently developing precipitation-flood-debris flow forecasting technologies, and all have a history of work on natural hazards both domestically and overseas. NOM has the capability to provide tracking and prediction of storm rainfall, trajectory and landfall and is developing flood probability and magnTtude capabilities. The USGS has the capability to evaluate the ambient stability of natural and man-made landforms, to assess landslide susceptibilities for those landforms, and to establish probabilities for initiation of landslides and debris flows. Additionally, the USGS has well-developed operational capacity for real-time monitoring and reporting of streamflow across distributed networks of automated gaging stations (http://water.usgs.gov/waterwatch/). NASA has the capability to provide sophisticated algorithms for satellite remote sensing of precipitation, land use, and in the future, soil moisture. The Workshop sought to initiate discussion among three agencies regarding their specific and highly complimentary capabilities. The fundamental goal of the Workshop was to establish a framework that will leverage the strengths of each agency. Once a prototype system is developed for example, in relatively data-rich Puerto Rim, it could be adapted for use in data-poor, low-infrastructure regions such as the Dominican Republic or Haiti. This paper provides an overview of the Workshop s goals

  15. Mentorship: The Education-Research Continuum

    Energy Technology Data Exchange (ETDEWEB)

    Correll, D

    2008-05-29

    Mentoring of science students stems naturally from the intertwined link between science education and science research. In fact, the mentoring relationship between a student and a scientist may be thought of analogically as a type of double helix forming the 'DNA' that defines the blueprint for the next generation of scientists. Although this analogy would not meet the rigorous tests commonly used for exploring the natural laws of the universe, the image depicted does capture how creating and sustaining the future science workforce benefits greatly from the continuum between education and research. The path science students pursue from their education careers to their research careers often involves training under an experienced and trusted advisor, i.e., a mentor. For many undergraduate science students, a summer research internship at a DOE National Laboratory is one of the many steps they will take in their Education-Research Continuum. Scientists who choose to be mentors share a commitment for both science education and science research. This commitment is especially evident within the research staff found throughout the Department of Energy's National Laboratories. Research-based internship opportunities within science, technology, engineering and mathematics (STEM) exist at most, if not all, of the Laboratories. Such opportunities for students are helping to create the next generation of highly trained professionals devoted to the task of keeping America at the forefront of scientific innovation. 'The Journal of Undergraduate Research' (JUR) provides undergraduate interns the opportunity to publish their scientific innovation and to share their passion for education and research with fellow students and scientists. The theme of this issue of the JUR (Vol. 8, 2008) is 'Science for All'. Almost 20 years have passed since the American Association for the Advancement of Science published its 1989 report, 'Science for All

  16. Evaluation the Effectiveness of the US Navy Leadership Continuum Curricula

    National Research Council Canada - National Science Library

    Duncan-White, Delores

    1997-01-01

    .... A Leadership Continuum Survey Questionnaire was developed to identified and analyze the student's attitudes concerning the effectiveness of the knowledge and skills taught in the course and how these...

  17. Equivalent-Continuum Modeling of Nano-Structured Materials

    Science.gov (United States)

    Odegard, Gregory M.; Gates, Thomas S.; Nicholson, Lee M.; Wise, Kristopher E.

    2001-01-01

    A method has been developed for modeling structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with an equivalent-continuum model. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As an important example with direct application to the development and characterization of single-walled carbon nanotubes, the model has been applied to determine the effective continuum geometry of a graphene sheet. A representative volume element of the equivalent-continuum model has been developed with an effective thickness. This effective thickness has been shown to be similar to, but slightly smaller than, the interatomic spacing of graphite.

  18. Asymmetric continuum extreme processes in solids and fluids

    CERN Document Server

    Teisseyre, Roman

    2014-01-01

    This book deals with a class of basic deformations in asymmetric continuum theory. It describes molecular deformations and transport velocities in fluids, strain deformations in solids as well as the molecular transport, important in fracture processes.

  19. IUTAM-Symposium on The Generalized Cosserat Continuum and the Continuum Theory of Dislocations with Applications

    CERN Document Server

    1968-01-01

    5 The symposium was held in Freudenstadt from 28\\h to 31 \\ ofAugust st nd 1967 and in Stuttgart from 1 to 2 of September 1967. The proposal to hold this symposium originated with the German Society of Applied Mathematics and Mechanics (GAMM) late in 1964 and was examined by a committee of IUTAM especially appointed for this purpose. The basis of this examination was a report in which the present situation in the field and the possible aims of the symposium were surveyed. Briefly, the aims of the symposium were stated to be 1. the unification of the various approaches developed in recent years with the aim of penetrating into the microscopic world of matter by means of continuum theories; 2. the bridging of the gap between microscopic (or atomic) research on mechanics on one hand, and the phenomenological (or continuum mechanical) approach on the other hand; 3. the physical interpretation and the relation to actual material behaviour of the quantities and laws introduced into the new theories, together with ap...

  20. Bursts and shocks in a continuum shell model

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Bohr, Tomas; Jensen, M.H.

    1998-01-01

    We study a burst event, i.e., the evolution of an initial condition having support only in a finite interval of k-space, in the continuum shell model due to Parisi. We show that the continuum equation without forcing or dissipation can be explicitly written in characteristic form and that the right...... and left moving parts can be solved exactly. When this is supplemented by the approximate shock condition it is possible to find the symptotic form of the burst....

  1. Progress in Using Continuum radiation for AXAF Calibration

    Science.gov (United States)

    Kolodziejczak, J. J.; Austin, R. A.; Elsner, R. F.; O'Dell, S. L.; Sulkanen, M. E.; Swartz, D. A.; Tennant, A. F.; Weisskopf, M. C.; Zirnstein, G.; McDermott, W. C.; hide

    1998-01-01

    X-ray calibration of the AXAF observatory at MSFC's X-Ray Calibration Facility (XRCF) made novel use of the x-ray continuum from a conventional electron-impact source. Taking advantage of the good spectral resolution of solid-state detectors, continuum measurements proved advantageous in calibrating the effective area of AXAF's High-Resolution Mirror Assembly (HRMA) and in verifying its alignment to the XRCF's optical axis. Further verification of AXAF response models will be presented.

  2. Uses of continuum radiation in the AXAF calibration

    Science.gov (United States)

    Kolodziejczak, J. J.; Austin, R. A.; Elsner, R. F.; O'Dell, S. L.; Sulkanen, M. E.; Swartz, D. A.; Tennant, A. F.; Weisskopf, M. C.; Zirnstein, G.; McDermott, W. C.

    1997-01-01

    X-ray calibration of the Advanced X-ray Astrophysics Facility (AXAF) observatory at the MSFC X-Ray Calibration Facility (XRCF) made novel use of the x-ray continuum from a conventional electron-impact source. Taking advantage of the good spectral resolution of solid-state detectors, continuum measurements proved advantageous in calibrating the effective area of AXAF's High-Resolution Mirror Assembly (HRMA) and in verifying its alignment to the XRCF's optical axis.

  3. Renormalization group and continuum limit of quantum cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Zimboras, Zoltan [Quantum Information Theory Group, ISI, Torino (Italy)

    2012-07-01

    We develop a renormalization group formalism for quantum cellular automata (reminiscent of the algebraic renormalization group of Buchholz and Verch). Using this formalism, we can define the continuum limit for certain automata. As a particular example, we show that the continuum limit of the so-called ''Glider Clifford cellular automaton'' is the 1+1 dimensional relativistic QFT of free Majorana fermions.

  4. Assessing continuum postulates in simulations of granular flow

    OpenAIRE

    Rycroft, Chris

    2009-01-01

    Continuum mechanics relies on the fundamental notion of a mesoscopic volume "element" in which properties averaged over discrete particles obey deterministic relationships. Recent work on granular materials suggests a continuum law may be inapplicable, revealing inhomogeneities at the particle level, such as force chains and slow cage breaking. Here, we analyze large-scale three-dimensional Discrete-Element Method (DEM) simulations of different granular flows and show that an approximate "gra...

  5. Forest drainage

    Science.gov (United States)

    R.W. Skaggs; S. Tian; G.M. Chescheir; Devendra Amatya; M.A. Youssef

    2016-01-01

    Most of the world's 4030 million ha of forested lands are situated on hilly, mountainous or well-drained upland landscapes where improved drainage is not needed. However, there are millions of hectares of poorly drained forested lands where excessively wet soil conditions limit tree growth and access for harvesting and other management activities. Improved or...

  6. Forest resources of the Gila National Forest

    Science.gov (United States)

    John D. Shaw

    2008-01-01

    The Interior West Forest Inventory and Analysis (IWFIA) program of the USDA Forest Service, Rocky Mountain Research Station, as part of its national Forest Inventory and Analysis (FIA) duties, conducted forest resource inventories of the Southwestern Region (Region 3) National Forests. This report presents highlights of the Gila National Forest 1994 inventory including...

  7. A CONTINUUM HARD-SPHERE MODEL OF PROTEIN ADSORPTION.

    Science.gov (United States)

    Finch, Craig; Clarke, Thomas; Hickman, James J

    2013-07-01

    Protein adsorption plays a significant role in biological phenomena such as cell-surface interactions and the coagulation of blood. Two-dimensional random sequential adsorption (RSA) models are widely used to model the adsorption of proteins on solid surfaces. Continuum equations have been developed so that the results of RSA simulations can be used to predict the kinetics of adsorption. Recently, Brownian dynamics simulations have become popular for modeling protein adsorption. In this work a continuum model was developed to allow the results from a Brownian dynamics simulation to be used as the boundary condition in a computational fluid dynamics (CFD) simulation. Brownian dynamics simulations were used to model the diffusive transport of hard-sphere particles in a liquid and the adsorption of the particles onto a solid surface. The configuration of the adsorbed particles was analyzed to quantify the chemical potential near the surface, which was found to be a function of the distance from the surface and the fractional surface coverage. The near-surface chemical potential was used to derive a continuum model of adsorption that incorporates the results from the Brownian dynamics simulations. The equations of the continuum model were discretized and coupled to a CFD simulation of diffusive transport to the surface. The kinetics of adsorption predicted by the continuum model closely matched the results from the Brownian dynamics simulation. This new model allows the results from mesoscale simulations to be incorporated into micro- or macro-scale CFD transport simulations of protein adsorption in practical devices.

  8. A Framework for Health Communication Across the HIV Treatment Continuum

    Science.gov (United States)

    Van Lith, Lynn M.; Mallalieu, Elizabeth C.; Packman, Zoe R.; Myers, Emily; Ahanda, Kim Seifert; Harris, Emily; Gurman, Tilly; Figueroa, Maria-Elena

    2017-01-01

    Background: As test and treat rolls out, effective interventions are needed to address the determinants of outcomes across the HIV treatment continuum and ensure that people infected with HIV are promptly tested, initiate treatment early, adhere to treatment, and are virally suppressed. Communication approaches offer viable options for promoting relevant behaviors across the continuum. Conceptual Framework: This article introduces a conceptual framework, which can guide the development of effective health communication interventions and activities that aim to impact behaviors across the HIV treatment continuum in low- and medium-income countries. The framework includes HIV testing and counseling, linkage to care, retention in pre-antiretroviral therapy and antiretroviral therapy initiation in one single-stage linkage to care and treatment, and adherence for viral suppression. The determinants of behaviors vary across the continuum and include both facilitators and barriers with communication interventions designed to focus on specific determinants presented in the model. At each stage, relevant determinants occur at the various levels of the social–ecological model: intrapersonal, interpersonal, health services, community, and policy. Effective health communication interventions have mainly relied on mHealth, interpersonal communication through service providers and peers, community support groups, and treatment supporters. Discussion: The conceptual framework and evidence presented highlight areas across the continuum where health communication can significantly impact treatment outcomes to reach the 90-90-90 goals by strategically addressing key behavioral determinants. As test and treat rolls out, multifaceted health communication approaches will be critical. PMID:27930606

  9. Spectral periodicity of the spinon continuum in quantum spin ice

    Science.gov (United States)

    Chen, Gang

    2017-08-01

    Motivated by the rapid experimental progress of quantum spin ice materials, we study the dynamical properties of pyrochlore spin ice in the U(1) spin liquid phases. In particular, we focus on the spinon excitations that appear at high energies and show up as an excitation continuum in the dynamic spin structure factor. The keen connection between the crystal symmetry fractionalization of the spinons and the spectral periodicity of the spinon continuum is emphasized and explicitly demonstrated. When the spinon experiences a background π flux and the spinon continuum exhibits an enhanced spectral periodicity with a folded Brillouin zone, this spectral property can then be used to detect the spin quantum number fractionalization and U(1) spin liquid. Our prediction can be immediately examined by inelastic neutron-scattering experiments among quantum spin ice materials with Kramers' doublets. Further application to the non-Kramers' doublets is discussed.

  10. Continuum mechanics using Mathematica fundamentals, methods, and applications

    CERN Document Server

    Romano, Antonio

    2014-01-01

    This textbook's methodological approach familiarizes readers with the mathematical tools required to correctly define and solve problems in continuum mechanics. Covering essential principles and fundamental applications, this second edition of Continuum Mechanics using Mathematica® provides a solid basis for a deeper study of more challenging and specialized problems related to nonlinear elasticity, polar continua, mixtures, piezoelectricity, ferroelectricity, magneto-fluid mechanics, and state changes (see A. Romano, A. Marasco, Continuum Mechanics: Advanced Topics and Research Trends, Springer (Birkhäuser), 2010, ISBN 978-0-8176-4869-5). Key topics and features: * Concise presentation strikes a balance between fundamentals and applications * Requisite mathematical background carefully collected in two introductory chapters and one appendix * Recent developments highlighted through coverage of more significant applications to areas such as wave propagation, fluid mechanics, porous media, linear elasticity....

  11. Odd Systems in Deformed Relativistic Hartree Bogoliubov Theory in Continuum

    Science.gov (United States)

    Li, Lu-Lu; Meng, Jie; Ring, P.; Zhao, En-Guang; Zhou, Shan-Gui

    2012-04-01

    In order to describe the exotic nuclear structure in unstable odd-A or odd-odd nuclei, the deformed relativistic Hartree Bogoliubov theory in continuum is extended to incorporate the blocking effect due to the odd nucleon. For a microscopic and self-consistent description of pairing correlations, continuum, deformation, blocking effects, and the extended spatial density distribution in exotic nuclei, the deformed relativistic Hartree Bogoliubov equations are solved in a Woods—Saxon basis in which the radial wave functions have a proper asymptotic behavior at large r. The formalism and numerical details are provided. The code is checked by comparing the results with those of spherical relativistic continuum Hartree Bogoliubov theory in the nucleus 19O. The prolate deformed nucleus 15C is studied by examining the neutron levels and density distributions.

  12. Dislocations in the Spacetime Continuum: Framework for Quantum Physics

    Directory of Open Access Journals (Sweden)

    Millette P. A.

    2015-10-01

    Full Text Available This paper provides a framework for the physical description of physical processes at the quantum level based on dislocations in the spacetime continuum within STCED (Spacetime Continuum Elastodynamics. In this framework, photon and particle self- energies and interactions are mediated by the strain energy density of the dislocations, replacing the role played by virtual particles in QED. We postulate that the spacetime continuum has a granularity characterized by a length b 0 corresponding to the smallest STC elementary Burgers dislocation-displacement vector. Screw dislocations corre- sponding to transverse displacements are identified with photons, and edge dislocations corresponding to longitudinal displacements are identified with particles. Mixed dislo- cations give rise to wave-particle duality. The strain energy density of the dislocations are calculated and proposed to explain the QED problem of mass renormalization.

  13. ICMS Workshop on Differential Geometry and Continuum Mechanics

    CERN Document Server

    Grinfeld, Michael; Knops, R

    2015-01-01

    This book examines the exciting interface between differential geometry and continuum mechanics, now recognised as being of increasing technological significance. Topics discussed include isometric embeddings in differential geometry and the relation with microstructure in nonlinear elasticity, the use of manifolds in the description of microstructure in continuum mechanics, experimental measurement of microstructure, defects, dislocations, surface energies, and nematic liquid crystals. Compensated compactness in partial differential equations is also treated. The volume is intended for specialists and non-specialists in pure and applied geometry, continuum mechanics, theoretical physics, materials and engineering sciences, and partial differential equations. It will also be of interest to postdoctoral scientists and advanced postgraduate research students. These proceedings include revised written versions of the majority of papers presented by leading experts at the ICMS Edinburgh Workshop on Differential G...

  14. An advanced kinetic theory for morphing continuum with inner structures

    Science.gov (United States)

    Chen, James

    2017-12-01

    Advanced kinetic theory with the Boltzmann-Curtiss equation provides a promising tool for polyatomic gas flows, especially for fluid flows containing inner structures, such as turbulence, polyatomic gas flows and others. Although a Hamiltonian-based distribution function was proposed for diatomic gas flow, a general distribution function for the generalized Boltzmann-Curtiss equations and polyatomic gas flow is still out of reach. With assistance from Boltzmann's entropy principle, a generalized Boltzmann-Curtiss distribution for polyatomic gas flow is introduced. The corresponding governing equations at equilibrium state are derived and compared with Eringen's morphing (micropolar) continuum theory derived under the framework of rational continuum thermomechanics. Although rational continuum thermomechanics has the advantages of mathematical rigor and simplicity, the presented statistical kinetic theory approach provides a clear physical picture for what the governing equations represent.

  15. Continuum Theory of Phase Separation Kinetics for Active Brownian Particles

    Science.gov (United States)

    Stenhammar, Joakim; Tiribocchi, Adriano; Allen, Rosalind J.; Marenduzzo, Davide; Cates, Michael E.

    2013-10-01

    Active Brownian particles (ABPs), when subject to purely repulsive interactions, are known to undergo activity-induced phase separation broadly resembling an equilibrium (attraction-induced) gas-liquid coexistence. Here we present an accurate continuum theory for the dynamics of phase-separating ABPs, derived by direct coarse graining, capturing leading-order density gradient terms alongside an effective bulk free energy. Such gradient terms do not obey detailed balance; yet we find coarsening dynamics closely resembling that of equilibrium phase separation. Our continuum theory is numerically compared to large-scale direct simulations of ABPs and accurately accounts for domain growth kinetics, domain topologies, and coexistence densities.

  16. Resonantly Trapped Bound State in the Continuum Laser

    CERN Document Server

    Lepetit, Thomas; Kodigala, Ashok; Bahari, Babak; Fainman, Yeshaiahu; Kanté, Boubacar

    2015-01-01

    Cavities play a fundamental role in wave phenomena from quantum mechanics to electromagnetism and dictate the spatiotemporal physics of lasers. In general, they are constructed by closing all "doors" through which waves can escape. We report, at room temperature, a bound state in the continuum laser that harnesses optical modes residing in the radiation continuum but nonetheless may possess arbitrarily high quality factors. These counterintuitive cavities are based on resonantly trapped symmetry-compatible modes that destructively interfere. Our experimental demonstration opens exciting avenues towards coherent sources with intriguing topological properties for optical trapping, biological imaging, and quantum communication.

  17. Fractional Quantum Field Theory: From Lattice to Continuum

    Directory of Open Access Journals (Sweden)

    Vasily E. Tarasov

    2014-01-01

    Full Text Available An approach to formulate fractional field theories on unbounded lattice space-time is suggested. A fractional-order analog of the lattice quantum field theories is considered. Lattice analogs of the fractional-order 4-dimensional differential operators are proposed. We prove that continuum limit of the suggested lattice field theory gives a fractional field theory for the continuum 4-dimensional space-time. The fractional field equations, which are derived from equations for lattice space-time with long-range properties of power-law type, contain the Riesz type derivatives on noninteger orders with respect to space-time coordinates.

  18. Shape Modeling of a Concentric-tube Continuum Robot

    DEFF Research Database (Denmark)

    Bai, Shaoping; Xing, Charles Chuhao

    2012-01-01

    is modeled on the basis of energy approach for both the in-plane and out-plane cases. The torsional influences on the shape of the concentric-tube robots are considered. An experimental device was build for the model validation. The results of simulation and experiments are included and analyzed.......Concentric-tube continuum robots feature with simple and compact structures and have a great potential in medical applications. The paper is concerned with the shape modeling of a type of concentric-tube continuum robot built with a collection of super-elastic NiTiNol tubes. The mechanics...

  19. A Coupling Tool for Parallel Molecular Dynamics-Continuum Simulations

    KAUST Repository

    Neumann, Philipp

    2012-06-01

    We present a tool for coupling Molecular Dynamics and continuum solvers. It is written in C++ and is meant to support the developers of hybrid molecular - continuum simulations in terms of both realisation of the respective coupling algorithm as well as parallel execution of the hybrid simulation. We describe the implementational concept of the tool and its parallel extensions. We particularly focus on the parallel execution of particle insertions into dense molecular systems and propose a respective parallel algorithm. Our implementations are validated for serial and parallel setups in two and three dimensions. © 2012 IEEE.

  20. Resonance continuum coupling in high-permittivity dielectric metamaterials

    Science.gov (United States)

    Lepetit, Thomas; Akmansoy, Eric; Ganne, Jean-Pierre; Lourtioz, Jean-Michel

    2010-11-01

    A detailed investigation of resonance-continuum coupling is carried out both experimentally and theoretically in metamaterials based on high-permittivity dielectric subwavelength resonators. An original experimental scheme is designed at microwave frequencies, which mimics a periodic array of resonators. Fano resonances are discussed in the framework of temporal coupled mode theory for the cases where one or two resonator modes couples to the continuum. Fano lineshapes are unambiguously demonstrated experimentally for the single-mode case in agreement with theoretical modeling. Numerical evidence of resonance trapping is shown in the two-mode case when modes with the same symmetry coincide in frequency.

  1. Boreal forests

    Energy Technology Data Exchange (ETDEWEB)

    Essen, P.A.; Ericson, L. [Univ. of Umeaa, Dept. of Ecological Botany, Umeaa (Sweden); Ehnstroem, B. [Swedish Univ., of Agricultural Sciences, Swedish Threatened Species Unit, Uppsala (Sweden); Sjoeberg, K. [Swedish Univ. of Agricultural Sciences, Dept. of Animal Ecology, Umeaa (Sweden)

    1997-10-01

    We review patterns and processes important for biodiversity in the Fennoscandian boreal forest, describe man`s past and present impact and outline a strategy for conservation. Natural disturbances, particularly forest fire and gap formation, create much of the structural and functional diversity in forest ecosystems. Several boreal plants and animals are adapted to fire regimes. In contrast, many organisms (epiphytic lichens, fungi, invertebrates) require stable conditions with long continuity in canopy cover. The highly mechanized and efficient Fennoscandian forest industry has developed during the last century. The result is that most natural forest has been lost and that several hundreds of species, mainly cryptograms and invertebrates, are threatened. The forestry is now in a transition from exploitation to sustainable production and has recently incorporated some measures to protect the environment. Programmes for maintaining biodiversity in the boreal forest should include at least three parts. First, the system of forest reserves must be significantly improved through protection of large representative ecosystems and key biotopes that host threatened species. Second, we must restore ecosystem properties that have been lost or altered. Natural disturbance regimes must be allowed to operate or be imitated, for example by artificial fire management. Stand-level management should particularly increase the amount of coarse woody debris, the number of old deciduous trees and large, old conifers, by using partial cutting. Third, natural variation should also be mimicked at the landscape level, for example, by reducing fragmentation and increasing links between landscape elements. Long-term experiments are required to evaluate the success of different management methods in maintaining biodiversity in the boreal forest. (au) 260 refs.

  2. STATCONT: Statistical continuum level determination method for line-rich sources

    Science.gov (United States)

    Sanchez-Monge, A.; Schilke, P.; Ginsburg, A.; Cesaroni, R.; Schmiedeke, A.

    2017-04-01

    STATCONT determines the continuum emission level in line-rich spectral data by inspecting the intensity distribution of a given spectrum by using different statistical approaches. The sigma-clipping algorithm provides the most accurate continuum level determination, together with information on the uncertainty in its determination; this uncertainty is used to correct the final continuum emission level. In general, STATCONT obtains accuracies of products of the software are the continuum emission level, together with its uncertainty, and data cubes containing only spectral line emission, i.e. continuum-subtracted data cubes. STATCONT also includes the option to estimate the spectral index or variation of the continuum emission with frequency.

  3. Construction of a state evolution for Kawasaki dynamics in continuum

    Science.gov (United States)

    Berns, Christoph; Kondratiev, Yuri; Kutoviy, Oleksandr

    2013-06-01

    We consider conservative, non-equilibrium stochastic jump dynamics of interacting particles in continuum. These dynamics have a (grand canonical) Gibbs measure as invariant measure. The problem of existence of these dynamics is studied. The corresponding time evolution of correlation functions is constructed.

  4. A variational formulation of the polarizable continuum model.

    Science.gov (United States)

    Lipparini, Filippo; Scalmani, Giovanni; Mennucci, Benedetta; Cancès, Eric; Caricato, Marco; Frisch, Michael J

    2010-07-07

    Continuum solvation models are widely used to accurately estimate solvent effects on energy, structural and spectroscopic properties of complex molecular systems. The polarizable continuum model (PCM) is one of the most versatile among the continuum models because of the variety of properties that can be computed and the diversity of methods that can be used to describe the solute from molecular mechanics (MM) to sophisticated quantum mechanical (QM) post-self-consistent field methods or even hybrid QM/MM methods. In this contribution, we present a new formulation of PCM in terms of a free energy functional whose variational parameters include the continuum polarization (represented by the apparent surface charges), the solute's atomic coordinates and-possibly-its electronic density. The problem of finding the optimized geometry of the (polarized) solute, with the corresponding self-consistent reaction field, is recast as the minimization of this free energy functional, simultaneously with respect to all its variables. The numerous potential applications of this variational formulation of PCM are discussed, including simultaneous optimization of solute's geometry and polarization charges and extended Lagrangian dynamics. In particular, we describe in details the simultaneous optimization procedure and we include several numerical examples.

  5. A variational formulation of the polarizable continuum model

    Science.gov (United States)

    Lipparini, Filippo; Scalmani, Giovanni; Mennucci, Benedetta; Cancès, Eric; Caricato, Marco; Frisch, Michael J.

    2010-07-01

    Continuum solvation models are widely used to accurately estimate solvent effects on energy, structural and spectroscopic properties of complex molecular systems. The polarizable continuum model (PCM) is one of the most versatile among the continuum models because of the variety of properties that can be computed and the diversity of methods that can be used to describe the solute from molecular mechanics (MM) to sophisticated quantum mechanical (QM) post-self-consistent field methods or even hybrid QM/MM methods. In this contribution, we present a new formulation of PCM in terms of a free energy functional whose variational parameters include the continuum polarization (represented by the apparent surface charges), the solute's atomic coordinates and—possibly—its electronic density. The problem of finding the optimized geometry of the (polarized) solute, with the corresponding self-consistent reaction field, is recast as the minimization of this free energy functional, simultaneously with respect to all its variables. The numerous potential applications of this variational formulation of PCM are discussed, including simultaneous optimization of solute's geometry and polarization charges and extended Lagrangian dynamics. In particular, we describe in details the simultaneous optimization procedure and we include several numerical examples.

  6. Predicting Eating Disorder Continuum Groups: Hardiness and College Adjustment.

    Science.gov (United States)

    Simon-Boyd, Gail D.; Bieschke, Kathleen J.

    This study examined relationships between hardiness, college adjustment (academic adjustment, social adjustment, personal-emotional adjustment, institutional attachment) and eating disorder (ED) continuum categories in 122 female and 20 male college students. Students who exhibited a higher level of personal-emotional adjustment (PEA) to college…

  7. The Eating Disorders Continuum, Self-Esteem, and Perfectionism

    Science.gov (United States)

    Peck, Lisa D.; Lightsey, Owen Richard

    2008-01-01

    Among 261 undergraduate women, increased severity of eating disorders along a continuum was associated with decreased self-esteem, increased perfectionism, and increased scores on 7 subscales of the Eating Disorders Inventory-2. Women with eating disorders differed from both symptomatic women and asymptomatic women on all variables, whereas…

  8. Ultrafine Cohesive Powders: From Interparticle Contacts to Continuum Behaviour.

    NARCIS (Netherlands)

    Tykhoniuk, Rostyslav; Tomas, Jürgen; Luding, Stefan; Kappl, Michael; Heim, Lars; Butt, Hans-Jürgen

    2007-01-01

    Continuum mechanical models and appropriate measuring methods to determine the material parameters are available to describe the flow behaviour of cohesive powders. These methods are successfully applied to design process equipment as silos. In addition, “microscopic” studies on the particle

  9. Scaling relation for determining the critical threshold for continuum ...

    Indian Academy of Sciences (India)

    We study continuum percolation of overlapping circular discs of two sizes. We propose a phenomenological scaling equation for the increase in the effective size of the larger discs due to the presence of the smaller discs. The critical percolation threshold as a function of the ratio of sizes of discs, for different values of the ...

  10. A New Conceptual Model for the Continuum of Land Rights

    African Journals Online (AJOL)

    Akrofi

    Abstract. This paper presents a new conceptual model for the land rights continuum. In developing the argument for the proposed model, the theoretical assumptions of the former model are challenged and an understanding of land rights and tenure elements is explored. The evolutionary approach is rejected in order to ...

  11. Autism genes: the continuum that connects us all

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 95; Issue 3. Autism genes: the continuum that connects us all. RASHMI PARIHAR SUBRAMANIAM GANESH. RESEARCH COMMENTARY Volume 95 Issue 3 September 2016 pp 481-483. Fulltext. Click here to view fulltext PDF. Permanent link:

  12. Autism genes: the continuum that connects us all

    Indian Academy of Sciences (India)

    RASHMI PARIHAR

    retardation—the fragile X syndrome (FXS), mostly affect- ing the males as in the case of ASD (Lozano et al. 2014). Although, the FXS patients share many of autistic features, the FMRP locus appears to be involved only in a minor. Keywords. polygenic disorders; genetic risk-factors; continuum traits. Journal of Genetics, DOI ...

  13. Cellular Automata in Topology Optimization of Continuum Structures ...

    African Journals Online (AJOL)

    In this paper, an optimization algorithm based on cellular automata (CA) is developed for topology optimization of continuum structures with shear and flexural behavior. The design domain is divided into small triangle elements and each cell is considered as a finite element. The stress analysis is performed by the Constant ...

  14. Levels of Mental Health Continuum and Personality Traits

    Science.gov (United States)

    Joshanloo, Mohsen; Nosratabadi, Masoud

    2009-01-01

    Empirically, mental health and mental illness are not opposite ends of a single measurement continuum. In view of this fact, Keyes ("J Health Soc Behav," 43:207-202, 2002) operationalizes mental health as a syndrome of symptoms of both positive feelings (emotional well-being) and positive functioning (psychological and social well-being)…

  15. Invariant Gait Continuum Based on the Duty-Factor

    DEFF Research Database (Denmark)

    Fihl, Preben; Moeslund, Thomas B.

    2008-01-01

    In this paper we present a method to describe the continuum of human gait in an invariant manner. The gait description is based on the duty-factor which is adopted from the biomechanics literature. We generate a database of artificial silhouettes representing the three main types of gait, i...

  16. The continuum shell-model neutron states of Pb

    Indian Academy of Sciences (India)

    model states with the collective vibrational states from giant resonances. The particle-vibration coupling model can be applied to understand the spreading pattern of the shell-model states lying in continuum region. The single-particle states are ...

  17. Shouldering the blame for impingement: the rotator cuff continuum

    African Journals Online (AJOL)

    Abstract. The aim of this article was to summarise recent research on shoulder impingement and rotator cuff pathology. A continuum model of rotator cuff pathology is described, and the challenges of accurate clinical diagnosis, imaging and best management discussed. ..... aging and morphologic changes in the rotator cuff.

  18. Photon pairs: Quantum chromodynamics continuum and the Higgs ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... ... predictions in the range of transverse momentum where the cross-section is the largest. Results are compared with data from the Fermilab Tevatron and predictions are made for the large hadron collider. The QCD continuum is shown to have a softer spectrum than the Higgs boson signal at the LHC.

  19. Photon pairs: Quantum chromodynamics continuum and the Higgs ...

    Indian Academy of Sciences (India)

    is the largest. Results are compared with data from the Fermilab Tevatron and predictions are made for the large hadron collider. The QCD continuum is shown to have a softer spectrum than the Higgs boson signal at the LHC. Keywords. Higgs; photon pairs; quantum chromodynamics. PACS Nos 12.15.Ji; 12.38.Cy; 13.85.

  20. A 45-MHz continuum survey of the southern hemisphere

    Science.gov (United States)

    Alvarez, H.; Aparici, J.; May, J.; Olmos, F.

    1997-08-01

    We present a survey of the 45-MHz continuum emission south of delta=+19.1°. The observations were made with a transit array having a beam 4.6° (\\alpha) \\times 2.4° (\\delta), full width at half maximum (FWHM). The results are given in sets of maps in galactic and equatorial coordinates (Epoch 1950).

  1. Ratings of Attention Problems in ADHD: A Continuum

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2009-12-01

    Full Text Available To determine whether ADHD should be classified in three distinct DSM-IV diagnostic subtypes or a continuum of attention problems, maternal ratings of attention on the Child Behavior Check List (CBCL, in Durch boys at age 7, 10, and 12 years, were fitted to class models, assuming either subtype or severity differences.

  2. Scaling relation for determining the critical threshold for continuum ...

    Indian Academy of Sciences (India)

    Abstract. We study continuum percolation of overlapping circular discs of two sizes. We propose a phenomenological scaling equation for the increase in the effective size of the larger discs due to the presence of the smaller discs. The critical percolation threshold as a function of the ratio of sizes of discs, for different values ...

  3. Continuum contribution to excitonic four-wave mixing

    DEFF Research Database (Denmark)

    Birkedal, Dan; Sayed, Karim El; Vadim, Lyssenko

    1996-01-01

    Summary form only given. We present an experimental and theoretical investigation of ultrafast transient four-wave mixing (TFWM) of GaAs-AlGaAs quantum wells for simultaneous excitation of exciton and continuum states. Recent TFWM experiments on semiconductors have shown unexpected results when b...

  4. Shouldering the blame for impingement: the rotator cuff continuum ...

    African Journals Online (AJOL)

    ... research on shoulder impingement and rotator cuff pathology. A continuum model of rotator cuff pathology is described, and the challenges of accurate clinical diagnosis, imaging and best management discussed. Keywords: shoulder impingement syndrome, subacromial impingement syndrome, rotator cuff, tendinopathy, ...

  5. Relativistic continuum random phase approximation in spherical nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Daoutidis, Ioannis

    2009-10-01

    Covariant density functional theory is used to analyze the nuclear response in the external multipole fields. The investigations are based on modern functionals with zero range and density dependent coupling constants. After a self-consistent solution of the Relativistic Mean Field (RMF) equations for the nuclear ground states multipole giant resonances are studied within the Relativistic Random Phase Approximation (RRPA), the small amplitude limit of the time-dependent RMF. The coupling to the continuum is treated precisely by calculating the single particle Greens-function of the corresponding Dirac equation. In conventional methods based on a discretization of the continuum this was not possible. The residual interaction is derived from the same RMF Lagrangian. This guarantees current conservation and a precise decoupling of the Goldstone modes. For nuclei with open shells pairing correlations are taken into account in the framework of BCS theory and relativistic quasiparticle RPA. Continuum RPA (CRPA) presents a robust method connected with an astonishing reduction of the numerical effort as compared to conventional methods. Modes of various multipolarities and isospin are investigated, in particular also the newly discovered Pygmy modes in the vicinity of the neutron evaporation threshold. The results are compared with conventional discrete RPA calculations as well as with experimental data. We find that the full treatment of the continuum is essential for light nuclei and the study of resonances in the neighborhood of the threshold. (orig.)

  6. The Continuum of Literacy in American Indian Communities.

    Science.gov (United States)

    Zepeda, Ofelia

    1995-01-01

    Describes the O'odham language and oral tradition of the Tohono O'odham Indians of southern Arizona, relating it to the development of O'odham children's English literacy. Oral tradition and school literacy constitute opposite ends of a literacy continuum, in which English literacy is often isolated from and in conflict with O'odham literacy. (10…

  7. Autism genes: the continuum that connects us all

    Indian Academy of Sciences (India)

    Such children also tend to show repetitive behaviours. (Boyd et al. 2013). The severity varies from being ... children born to older parents, and environmental factors are a few of the other risk factors (Matelski and Van ... genetic risk-factors; continuum traits. Journal of Genetics, DOI 10.1007/s12041-016-0688-0, Vol. 95, No.

  8. Framework to Assess Multiclass Continuum Traffic Flow Models

    NARCIS (Netherlands)

    van Wageningen-Kessels, F.L.M.

    2016-01-01

    Since the beginning of this millennium, many models of multiclass continuum traffic flow have been proposed. A set of qualitative requirements is presented for this type of model, including nonincreasing density–speed relationships and anisotropy. The requirements are cast into a framework that

  9. Continuum of Medical Education in Obstetrics and Gynecology.

    Science.gov (United States)

    Dohner, Charles W.; Hunter, Charles A., Jr.

    1980-01-01

    Over the past eight years the obstetric and gynecology specialty has applied a system model of instructional planning to the continuum of medical education. The systems model of needs identification, preassessment, instructional objectives, instructional materials, learning experiences; and evaluation techniques directly related to objectives was…

  10. Water Continuum Absorption in the Infrared and Millimeter Spectral Regions.

    Science.gov (United States)

    Ma, Qiancheng

    1990-01-01

    The absorption coefficient due to the water continuum is calculated both in the high-frequency (infrared) wing and in the low-frequency (millimeter) wing of the pure rotational band. The statistical theory proposed by Rosenkranz to calculate the continuum absorption in the high-frequency wing is reviewed and extended. In this review, we discuss specifically the validity and the limitation of the approximations made by Rosenkranz. We then discuss several extensions to his theory, including increasing the number of rotational states used to calculate the band-average relaxation parameter, correcting the normalization factor, and eliminating the "boxcar approximation." These improvements allow us to eliminate some inconsistencies in the original formulation of Rosenkranz while obtaining substantially the same final results. As a consequence, we confirm his conclusions about the origin, magnitude, and temperature-dependence of the water continuum absorption in the high-frequency wing of the pure rotational band. A new theory is developed to calculate the continuum in the low-frequency wing, i.e., in the millimeter spectral region. This theory is based on a generalization of Fano's theory in which the spectral density is calculated for a system consisting of a pair of water molecules. The internal states are written in terms of the line space of the system, and the resolvent operator is obtained using the Lanczos algorithm. For the interaction between two water molecules, we include only the leading dipole-dipole anisotropic potential and model the isotropic interaction by a Lennard-Jones potential. Using reasonable values for the two Lennard-Jones potential parameters, and the known rotational constants and permanent dipole moment of a water molecule, we calculate the absorption coefficient for frequencies up to 450 GHz for temperatures between 282 and 315 K. Without any free parameters, the present results are in good agreement with an empirical model for the water

  11. Georgia's forests, 2004

    Science.gov (United States)

    Richard A. Harper; Nathan D. McClure; Tony G. Johnson; J. Frank Green; James K. Johnson; David B. Dickinson; James L. Chamerlain; KaDonna C. Randolph; Sonja N. Oswalt

    2009-01-01

    Between 1997 and 2004, the Forest Service, Forest Inventory and Analysis Program conducted the eighth inventory of Georgia forests. Forest land area remained stable at 24.8 million acres, and covered about two-thirds of the land area in Georgia. About 24.2 million acres of forest land was considered timberland and 92 percent of that was privately owned. Family forest...

  12. Automatic Identification of LAMOST Spectra with Continuum Problem Based on High Performance Computing

    Science.gov (United States)

    Yu, Jingjing; Pan, Jingchang; Meng, Fanlong

    2017-10-01

    Continuum problem is a phenomenon that the continuum of spectra get off their actual continuum even break off due to interstellar extinction and flux calibration, and it will have negative impact on the subsequent process such as spectral line extraction and so on. Based on this problem and fully considering of the continuum features of the stellar spectra, a method of automatic detection and recognition of the continuum problem in the stellar spectra based on High Performance Computing (HPC) is proposed, which will improve work efficiency greatly compared with the traditional human eyes examination under the condition of maintaining high accuracy. Continuum template matching is used to identify the continuum problem spectra in this paper. The first step goes to fit continuum of the test stellar spectra and the template spectra, then the flux differences of the two continuum we fitted before at every point of wavelength in the continuum spectra will be calculated based on full spectra matching to analyze the features of its distribution. The features we count are average (called β) value and standard deviation (called δ). The percentage of points distributed in rangeβ±ɑ*δwill be detected to confirm that if there is continuum problem. Experiments was taken to identify the continuum problem spectra on HPC, which demonstrate the validity and efficiency of the method, and this has important reference value to resolve similar massive spectra data processing problems in the future.

  13. Derivation of Electromagnetism from the Elastodynamics of the Spacetime Continuum

    Directory of Open Access Journals (Sweden)

    Millette P. A.

    2013-04-01

    Full Text Available We derive Electromagnetism from the Elastodynamics of the Spacetime Continuum based on the identification of the theory’s antisymmetric rotation tensor with the elec- tromagnetic field-strength tensor. The theory provides a physical explanation of the electromagnetic potential, which arises from transverse ( shearing displacements of the spacetime continuum, in contrast to mass which arises from longitudinal (dilatational displacements. In addition, the theory provides a physical explanation of the current density four-vector, as the 4-gradient of the volume dilatation of the spacetime con- tinuum. The Lorentz condition is obtained directly from the theory. In addition, we obtain a generalization of Electromagnetism for the situation where a volume force is present, in the general non-macroscopic case. Maxwell’s equations are found to remain unchanged, but the current density has an additional term proportional to the volume force.

  14. Antieigenvalue analysis for continuum mechanics, economics, and number theory

    Directory of Open Access Journals (Sweden)

    Gustafson Karl

    2016-01-01

    Full Text Available My recent book Antieigenvalue Analysis, World-Scientific, 2012, presented the theory of antieigenvalues from its inception in 1966 up to 2010, and its applications within those forty-five years to Numerical Analysis, Wavelets, Statistics, Quantum Mechanics, Finance, and Optimization. Here I am able to offer three further areas of application: Continuum Mechanics, Economics, and Number Theory. In particular, the critical angle of repose in a continuum model of granular materials is shown to be exactly my matrix maximum turning angle of the stress tensor of the material. The important Sharpe ratio of the Capital Asset Pricing Model is now seen in terms of my antieigenvalue theory. Euclid’s Formula for Pythagorean triples becomes a special case of my operator trigonometry.

  15. Continuum-mediated dark matter–baryon scattering

    CERN Document Server

    Katz, Andrey; Sajjad, Aqil

    2016-01-01

    Many models of dark matter scattering with baryons may be treated either as a simple contact interaction or as the exchange of a light mediator particle. We study an alternative, in which a continuum of light mediator states may be exchanged. This could arise, for instance, from coupling to a sector which is approximately conformal at the relevant momentum transfer scale. In the non-relativistic effective theory of dark matter-baryon scattering, which is useful for parametrizing direct detection signals, the effect of such continuum mediators is to multiply the amplitude by a function of the momentum transfer q, which in the simplest case is just a power law. We develop the basic framework and study two examples: the case where the mediator is a scalar operator coupling to the Higgs portal (which turns out to be highly constrained) and the case of an antisymmetric tensor operator ${\\cal O}_{\\mu \

  16. Wave propagation in equivalent continuums representing truss lattice materials

    Energy Technology Data Exchange (ETDEWEB)

    Messner, Mark C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Barham, Matthew I. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kumar, Mukul [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Barton, Nathan R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-29

    Stiffness scales linearly with density in stretch-dominated lattice meta-materials offering the possibility of very light yet very stiff structures. Current additive manufacturing techniques can assemble structures consisting of these lattice materials, but the design of such structures will require accurate, efficient simulation techniques. Equivalent continuum models have several advantages over discrete truss models of stretch dominated lattices, including computational efficiency and ease of model construction. However, the development an equivalent model suitable for representing the dynamic response of a periodic truss is complicated by microinertial effects. This paper derives a dynamic equivalent continuum model for periodic truss structures and verifies it against detailed finite element simulations. The model must incorporate microinertial effects to accurately reproduce long-wavelength characteristics of the response such as anisotropic elastic soundspeeds. The formulation presented here also improves upon previous work by preserving equilibrium at truss joints for affine lattice deformation and by improving numerical stability by eliminating vertices in the effective yield surface.

  17. Topology and layout optimization of discrete and continuum structures

    Science.gov (United States)

    Bendsoe, Martin P.; Kikuchi, Noboru

    1993-01-01

    The basic features of the ground structure method for truss structure an continuum problems are described. Problems with a large number of potential structural elements are considered using the compliance of the structure as the objective function. The design problem is the minimization of compliance for a given structural weight, and the design variables for truss problems are the cross-sectional areas of the individual truss members, while for continuum problems they are the variable densities of material in each of the elements of the FEM discretization. It is shown how homogenization theory can be applied to provide a relation between material density and the effective material properties of a periodic medium with a known microstructure of material and voids.

  18. Continuum mechanics through the twentieth century a concise historical perspective

    CERN Document Server

    Maugin, Gerard A

    2013-01-01

    This overview of the development of continuum mechanics throughout the twentieth century is unique and ambitious. Utilizing a historical perspective, it combines an exposition on the technical progress made in the field and a marked interest in the role played by remarkable individuals and scientific schools and institutions on a rapidly evolving social background. It underlines the newly raised technical questions and their answers, and the ongoing reflections on the bases of continuum mechanics associated, or in competition, with other branches of the physical sciences, including thermodynamics. The emphasis is placed on the development of a more realistic modeling of deformable solids and the exploitation of new mathematical tools. The book presents a balanced appraisal of advances made in various parts of the world. The author contributes his technical expertise, personal recollections, and international experience to this general overview, which is very informative albeit concise.

  19. PCE: web tools to compute protein continuum electrostatics

    Science.gov (United States)

    Miteva, Maria A.; Tufféry, Pierre; Villoutreix, Bruno O.

    2005-01-01

    PCE (protein continuum electrostatics) is an online service for protein electrostatic computations presently based on the MEAD (macroscopic electrostatics with atomic detail) package initially developed by D. Bashford [(2004) Front Biosci., 9, 1082–1099]. This computer method uses a macroscopic electrostatic model for the calculation of protein electrostatic properties, such as pKa values of titratable groups and electrostatic potentials. The MEAD package generates electrostatic energies via finite difference solution to the Poisson–Boltzmann equation. Users submit a PDB file and PCE returns potentials and pKa values as well as color (static or animated) figures displaying electrostatic potentials mapped on the molecular surface. This service is intended to facilitate electrostatics analyses of proteins and thereby broaden the accessibility to continuum electrostatics to the biological community. PCE can be accessed at . PMID:15980492

  20. Continuum Kinetic and Multi-Fluid Simulations of Classical Sheaths

    CERN Document Server

    Cagas, Petr; Juno, James; Srinivasan, Bhuvana

    2016-01-01

    The kinetic study of plasma sheaths is critical, among other things, to understand the deposition of heat on walls, the effect of sputtering, and contamination of the plasma with detrimental impurities. The plasma sheath also provides a boundary condition and can often have a significant global impact on the bulk plasma. In this paper, kinetic studies of classical sheaths are performed with the continuum code, Gkeyll, that directly solves the Vlasov-Poisson/Maxwell equations. The code uses a novel version of the finite-element discontinuous Galerkin (DG) scheme that conserves energy in the continuous-time limit. The electrostatic field is computed using the Poisson equation. Ionization and scattering collisions are included, however, surface effects are neglected. The aim of this work is to introduce the continuum-kinetic method and compare its results to those obtained from an already established finite-volume multi-fluid model also implemented in Gkeyll. Novel boundary conditions on the fluids allow the she...

  1. The Glymphatic-Lymphatic Continuum: Opportunities for Osteopathic Manipulative Medicine.

    Science.gov (United States)

    Hitscherich, Kyle; Smith, Kyle; Cuoco, Joshua A; Ruvolo, Kathryn E; Mancini, Jayme D; Leheste, Joerg R; Torres, German

    2016-03-01

    The brain has long been thought to lack a lymphatic drainage system. Recent studies, however, show the presence of a brain-wide paravascular system appropriately named the glymphatic system based on its similarity to the lymphatic system in function and its dependence on astroglial water flux. Besides the clearance of cerebrospinal fluid and interstitial fluid, the glymphatic system also facilitates the clearance of interstitial solutes such as amyloid-β and tau from the brain. As cerebrospinal fluid and interstitial fluid are cleared through the glymphatic system, eventually draining into the lymphatic vessels of the neck, this continuous fluid circuit offers a paradigm shift in osteopathic manipulative medicine. For instance, manipulation of the glymphatic-lymphatic continuum could be used to promote experimental initiatives for nonpharmacologic, noninvasive management of neurologic disorders. In the present review, the authors describe what is known about the glymphatic system and identify several osteopathic experimental strategies rooted in a mechanistic understanding of the glymphatic-lymphatic continuum.

  2. Simulation of mixing-limited reactions using a continuum approach

    Science.gov (United States)

    Barnard, Jack M.

    2017-06-01

    The limiting of reaction rates in porous media due to the imperfect mixing of reactants is a well studied phenomenon. It has been observed on both the field and laboratory scale and studied using a range of numerical techniques including continuum approaches and Lagrangian particle tracking methods. A new method is presented here for the simulation of mixing-limited reactions using continuum methods, based on the idea of separating each reactant into a mixed and an unmixed fraction, of which only the mixed fraction can react. The method is shown to be capable of producing mixing-limited reaction rates associated with one-, two-, and three-dimensional systems, and of producing outputs well fitted to the experimental data presented in Gramling et al. (2002) .

  3. The continuum of spreading depolarizations in acute cortical lesion development

    DEFF Research Database (Denmark)

    Hartings, Jed A; Shuttleworth, C William; Kirov, Sergei A

    2017-01-01

    A modern understanding of how cerebral cortical lesions develop after acute brain injury is based on Aristides Leão's historic discoveries of spreading depression and asphyxial/anoxic depolarization. Treated as separate entities for decades, we now appreciate that these events define a continuum....... The causal role of these waves in lesion development has been proven by real-time monitoring of electrophysiology, blood flow, and cytotoxic edema. The spreading depolarization continuum further applies to other models of acute cortical lesions, suggesting that it is a universal principle of cortical lesion...... development. These pathophysiologic concepts establish a working hypothesis for translation to human disease, where complex patterns of depolarizations are observed in acute brain injury and appear to mediate and signal ongoing secondary damage....

  4. Finsler-Geometric Continuum Dynamics and Shock Compression

    Science.gov (United States)

    2018-01-01

    conformal transformation . The dynamic theory is applied to describe shock loading of ceramic crystals of boron carbide, accounting for inelastic mechanisms...and to a lesser extent, by increasing the energy barrier for phase transformation . 15. SUBJECT TERMS continuum mechanics, differential geometry...of Engineering, University of Maryland, College Park , MD 20742, USA J. D. Clayton Impact Physics, US ARL, Aberdeen, MD 21005-5066, USA can vary

  5. Bound States in the Continuum in Nuclear and Hadron Physics

    CERN Document Server

    Lenske, H; Cao, Xu

    2015-01-01

    The population of bound states in the continuum and their spectral properties are studied on the nuclear and hadronic scale. The theoretical approach is presented and realizations in nuclear and charmonium spectroscopy are dis- cussed. The universality of the underlying dynamical principles is pointed out. Applications to nuclear systems at the neutron dripline and for charmonium spectroscopy by $e^- e^+ \\to D\\bar{D}$ production are discussed.

  6. Continuum-limit scaling of overlap fermions as valence quarks

    Energy Technology Data Exchange (ETDEWEB)

    Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2009-10-15

    We present the results of a mixed action approach, employing dynamical twisted mass fermions in the sea sector and overlap valence fermions, with the aim of testing the continuum limit scaling behaviour of physical quantities, taking the pion decay constant as an example. To render the computations practical, we impose for this purpose a fixed finite volume with lattice size L{approx}1.3 fm. We also briefly review the techniques we have used to deal with overlap fermions. (orig.)

  7. Nitrogen-induced absorption of oxygen in the Herzberg continuum

    Science.gov (United States)

    Shardanand, MR.

    1977-01-01

    Total absorption of O2 induced by collisions with N2 has been measured at room temperature in the Hersberg continuum using a one meter normal incidence grating monochromator. The enhanced absorption is ascribed to the formation of O2-O2 and O2-N2 dimers. The interaction constants for these dimers are determined and utilized to investigate their effect on the absorption of solar radiation in the stratosphere.

  8. Advanced methods of continuum mechanics for materials and structures

    CERN Document Server

    Aßmus, Marcus

    2016-01-01

    This volume presents a collection of contributions on advanced approaches of continuum mechanics, which were written to celebrate the 60th birthday of Prof. Holm Altenbach. The contributions are on topics related to the theoretical foundations for the analysis of rods, shells and three-dimensional solids, formulation of constitutive models for advanced materials, as well as development of new approaches to the modeling of damage and fractures.

  9. Dryland forests

    NARCIS (Netherlands)

    Bose, Purabi; Dijk, van Han

    2016-01-01

    This volume provides new insights and conceptual understandings of the human and gender dimension of vulnerability in relation to the dynamics of tenure reforms in the dryland forests of Asia and Africa. The book analyzes the interaction between biophysical factors such as climate variability

  10. Forest Fires

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 11. Forest Fires - Origins and Ecological Paradoxes. K Narendran. General Article Volume 6 Issue 11 November 2001 pp 34-41. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/11/0034-0041 ...

  11. Polarizable molecular dynamics in a polarizable continuum solvent.

    Science.gov (United States)

    Lipparini, Filippo; Lagardère, Louis; Raynaud, Christophe; Stamm, Benjamin; Cancès, Eric; Mennucci, Benedetta; Schnieders, Michael; Ren, Pengyu; Maday, Yvon; Piquemal, Jean-Philip

    2015-02-10

    We present, for the first time, scalable polarizable molecular dynamics (MD) simulations within a polarizable continuum solvent with molecular shape cavities and exact solution of the mutual polarization. The key ingredients are a very efficient algorithm for solving the equations associated with the polarizable continuum, in particular, the domain decomposition Conductor-like Screening Model (ddCOSMO), which involves a rigorous coupling of the continuum with the polarizable force field achieved through a robust variational formulation and an effective strategy to solve the coupled equations. The coupling of ddCOSMO with nonvariational force fields, including AMOEBA, is also addressed. The MD simulations are feasible, for real-life systems, on standard cluster nodes; a scalable parallel implementation allows for further acceleration in the context of a newly developed module in Tinker, named Tinker-HP. NVE simulations are stable, and long-term energy conservation can be achieved. This paper is focused on the methodological developments, the analysis of the algorithm, and the stability of the simulations; a proof-of-concept application is also presented to attest to the possibilities of this newly developed technique.

  12. Equivalent Continuum Modeling for Shock Wave Propagation in Jointed Media

    Energy Technology Data Exchange (ETDEWEB)

    Vorobiev, O; Antoun, T

    2009-12-11

    This study presents discrete and continuum simulations of shock wave propagating through jointed media. The simulations were performed using the Lagrangian hydrocode GEODYN-L with joints treated explicitly using an advanced contact algorithm. They studied both isotropic and anisotropic joint representations. For an isotropically jointed geologic medium, the results show that the properties of the joints can be combined with the properties of the intact rock to develop an equivalent continuum model suitable for analyzing wave propagation through the jointed medium. For an anisotropically jointed geologic medium, they found it difficult to develop an equivalent continuum (EC) model that matches the response derived from mesoscopic simulation. They also performed simulations of wave propagation through jointed media. Two appraoches are suggested for modeling the rock mass. In one approach, jointed are modeled explicitly in a Lagrangian framework with appropriate contact algorithms used to track motion along the interfaces. In the other approach, the effect of joints is taken into account using a constitutive model derived from mesoscopic simulations.

  13. Formation of the thermal infrared continuum in solar flares

    Science.gov (United States)

    Simões, Paulo J. A.; Kerr, Graham S.; Fletcher, Lyndsay; Hudson, Hugh S.; Giménez de Castro, C. Guillermo; Penn, Matt

    2017-09-01

    Aims: Observations of the Sun with the Atacama Large Millimeter Array have now started, and the thermal infrared will regularly be accessible from the NSF's Daniel K. Inouye Solar Telescope. Motivated by the prospect of these new data, and by recent flare observations in the mid infrared, we set out here to model and understand the source of the infrared continuum in flares, and to explore its diagnostic capability for the physical conditions in the flare atmosphere. Methods: We use the one-dimensional (1D) radiation hydrodynamics code RADYN to calculate mid-infrared continuum emission from model atmospheres undergoing sudden deposition of energy by non-thermal electrons. Results: We identify and characterise the main continuum thermal emission processes relevant to flare intensity enhancement in the mid- to far-infrared (2-200 μm) spectral range as free-free emission on neutrals and ions. We find that the infrared intensity evolution tracks the energy input to within a second, albeit with a lingering intensity enhancement, and provides a very direct indication of the evolution of the atmospheric ionisation. The prediction of highly impulsive emission means that, on these timescales, the atmospheric hydrodynamics need not be considered in analysing the mid-IR signatures.

  14. A Continuum Poisson-Boltzmann Model for Membrane Channel Proteins.

    Science.gov (United States)

    Xiao, Li; Diao, Jianxiong; Greene, D'Artagnan; Wang, Junmei; Luo, Ray

    2017-07-11

    Membrane proteins constitute a large portion of the human proteome and perform a variety of important functions as membrane receptors, transport proteins, enzymes, signaling proteins, and more. Computational studies of membrane proteins are usually much more complicated than those of globular proteins. Here, we propose a new continuum model for Poisson-Boltzmann calculations of membrane channel proteins. Major improvements over the existing continuum slab model are as follows: (1) The location and thickness of the slab model are fine-tuned based on explicit-solvent MD simulations. (2) The highly different accessibilities in the membrane and water regions are addressed with a two-step, two-probe grid-labeling procedure. (3) The water pores/channels are automatically identified. The new continuum membrane model is optimized (by adjusting the membrane probe, as well as the slab thickness and center) to best reproduce the distributions of buried water molecules in the membrane region as sampled in explicit water simulations. Our optimization also shows that the widely adopted water probe of 1.4 Å for globular proteins is a very reasonable default value for membrane protein simulations. It gives the best compromise in reproducing the explicit water distributions in membrane channel proteins, at least in the water accessible pore/channel regions. Finally, we validate the new membrane model by carrying out binding affinity calculations for a potassium channel, and we observe good agreement with the experimental results.

  15. Resilience among patients across the cancer continuum: diverse perspectives.

    Science.gov (United States)

    Molina, Yamile; Yi, Jean C; Martinez-Gutierrez, Javiera; Reding, Kerryn W; Yi-Frazier, Joyce P; Rosenberg, Abby R

    2014-02-01

    Each phase of the cancer experience profoundly affects patients' lives. Much of the literature has focused on negative consequences of cancer; however, the study of resilience may enable providers to promote more positive psychosocial outcomes before, during, and after the cancer experience. The current review describes the ways in which elements of resilience have been defined and studied at each phase of the cancer continuum. Extensive literature searches were conducted to find studies assessing resilience during one or more stages of the adult cancer continuum. For all phases of the cancer continuum, resilience descriptions included preexisting or baseline characteristics, such as demographics and personal attributes (e.g., optimism, social support), mechanisms of adaptation, such as coping and medical experiences (e.g., positive provider communication), as well as psychosocial outcomes, such as growth and quality of life. Promoting resilience is a critical element of patient psychosocial care. Nurses may enable resilience by recognizing and promoting certain baseline characteristics and optimizing mechanisms of adaptation.

  16. An Operational Framework for Defining and Monitoring Forest Degradation

    Directory of Open Access Journals (Sweden)

    Ian D. Thompson

    2013-06-01

    Full Text Available Forest degradation is broadly defined as a reduction in the capacity of a forest to produce ecosystem services such as carbon storage and wood products as a result of anthropogenic and environmental changes. The main causes of degradation include unsustainable logging, agriculture, invasive species, fire, fuelwood gathering, and livestock grazing. Forest degradation is widespread and has become an important consideration in global policy processes that deal with biodiversity, climate change, and forest management. There is, however, no generally recognized way to identify a degraded forest because perceptions of forest degradation vary depending on the cause, the particular goods or services of interest, and the temporal and spatial scales considered. Here, we suggest that there are types of forest degradation that produce a continuum of decline in provision of ecosystem services, from those in primary forests through various forms of managed forests to deforestation. Forest degradation must be measured against a desired baseline condition, and the types of degradation can be represented using five criteria that relate to the drivers of degradation, loss of ecosystem services and sustainable management, including: productivity, biodiversity, unusual disturbances, protective functions, and carbon storage. These criteria are not meant to be equivalent and some might be considered more important than others, depending on the local forest management objectives. We propose a minimum subset of seven indicators for the five criteria that should be assessed to determine forest degradation under a sustainable ecosystem management regime. The indicators can be remotely sensed (although improving calibration requires ground work and aggregated from stand to management unit or landscape levels and ultimately to sub-national and national scales.

  17. Forest ownership dynamics of southern forests

    Science.gov (United States)

    Brett J. Butler; David N. Wear

    2013-01-01

    Key FindingsPrivate landowners hold 86 percent of the forest area in the South; two-thirds of this area is owned by families or individuals.Fifty-nine percent of family forest owners own between 1 and 9 acres of forest land, but 60 percent of family-owned forests are in holdings of 100 acres or more.Two-...

  18. Combating Forest Corruption: the Forest Integrity Network

    NARCIS (Netherlands)

    Gupta, A.; Siebert, U.

    2004-01-01

    This article describes the strategies and activities of the Forest Integrity Network. One of the most important underlying causes of forest degradation is corruption and related illegal logging. The Forest Integrity Network is a timely new initiative to combat forest corruption. Its approach is to

  19. Forest resources of the Umatilla National Forest.

    Science.gov (United States)

    Glenn A. Christensen; Paul Dunham; David C. Powell; Bruce. Hiserote

    2007-01-01

    Current resource statistics for the Umatilla National Forest, based on two separate inventories conducted in 1993–96 and in 1997–2002, are presented in this report. Currently on the Umatilla National Forest, 89 percent of the land area is classified as forest land. The predominant forest type is grand fir (26 percent of forested acres) followed by the interior Douglas-...

  20. Forest thinking

    Directory of Open Access Journals (Sweden)

    Corona P

    2016-12-01

    Full Text Available This note emphasizes the importance of appreciating the conceptual paths and theories that have historically characterized forestry development. A recent monograph on the history of forest thinking presents the theoretical evolution of silvicultural science, with particular attention to epistemological and ethical implications: the main lines of research progress are stressed by analysing the various schools of thought in this field. The reading of the monograph strengthens the evidence that always behind the facts, there are the ideas.

  1. Dispersal of forest insects

    Science.gov (United States)

    Mcmanus, M. L.

    1979-01-01

    Dispersal flights of selected species of forest insects which are associated with periodic outbreaks of pests that occur over large contiguous forested areas are discussed. Gypsy moths, spruce budworms, and forest tent caterpillars were studied for their massive migrations in forested areas. Results indicate that large dispersals into forested areas are due to the females, except in the case of the gypsy moth.

  2. Tenure and forest income

    DEFF Research Database (Denmark)

    Jagger, Pamela; Luckert, Martin K.; Duchelle, Amy E.

    2014-01-01

    We explore the relationship between tenure and forest income in 271 villages throughout the tropics. We find that state-owned forests generate more forest income than private and community-owned forests both per household and per hectare. We explore whether forest income varies according to the e...

  3. Bacterial Biogeography across the Amazon River-Ocean Continuum

    Energy Technology Data Exchange (ETDEWEB)

    Doherty, Mary; Yager, Patricia L.; Moran, Mary Ann; Coles, Victoria J.; Fortunato, Caroline S.; Krusche, Alex V.; Medeiros, Patricia M.; Payet, Jérôme P.; Richey, Jeffrey E.; Satinsky, Brandon M.; Sawakuchi, Henrique O.; Ward, Nicholas D.; Crump, Byron C.

    2017-05-23

    Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ~675 km of the lower Amazon River mainstem, in the Tapajos River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity nearshore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and

  4. Block versus continuum deformation in the Western United States

    Science.gov (United States)

    King, G.; Oppenheimer, D.; Amelung, F.

    1994-01-01

    The relative role of block versus continuum deformation of continental lithosphere is a current subject of debate. Continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies. In contrast, block models are favored by geologic studies of displacement in places like Asia. A problem in this debate is a lack of data from which unequivocal conclusions may be reached. In this paper we apply the techniques of study used in regions such as the Alpine-Himalayan belt to an area with a wealth of instrumental data-the Western United States. By comparing plate rates to seismic moment release rates and assuming a typical seismogenic layer thickness of 15 km it appears that since 1850 about 60% of the Pacific-North America motion across the plate boundary in California and Nevada has occurred seismically and 40% aseismically. The San Francisco Bay area shows similar partitioning between seismic and aseismic deformation, and it can be shown that within the seismogenic depth range aseismic deformation is concentrated near the surface and at depth. In some cases this deformation can be located on creeping surface faults, but elsewhere it is spread over a several kilometer wide zone adjacent to the fault. These superficial creeping deformation zones may be responsible for the palaeomagnetic rotations that have been ascribed elsewhere to the surface expression of continuum deformation in the lithosphere. Our results support the dominant role of non-continuum deformation processes with the implication that deformation localization by strain softening must occur in the lower crust and probably the upper mantle. Our conclusions apply only to the regions where the data are good, and even within the Western United States (i.e., the Basin and Range) deformation styles remain poorly resolved. Nonetheless, we maintain that block motion is the

  5. Topology Optimization of Continuum Structures with Local Stress Constraints

    DEFF Research Database (Denmark)

    Duysinx, Pierre; Bendsøe, Martin P

    1997-01-01

    materials. Then, an empirical model is proposed for the power law materials (also called SIMP materials). In a second part, solution aspects of topology problems are considered. To deal with the so-called 'singularity' phenomenon of stress constraints in topology design, an $\\epsilon$ constraint relaxation......We introduce an extension of current technologies for topology optimization of continuum structures which allows for treating local stress criteria. We first consider relevant stress criteria for porous composite materials, initially by studying the stress states of the so-called rank~2 layered...

  6. Extragalactic radio continuum surveys and the transformation of radio astronomy

    Science.gov (United States)

    Norris, Ray P.

    2017-10-01

    Next-generation radio surveys are about to transform radio astronomy by discovering and studying tens of millions of previously unknown radio sources. These surveys will provide fresh insights for understanding the evolution of galaxies, measuring the evolution of the cosmic star-formation rate, and rivalling traditional techniques in the measurement of fundamental cosmological parameters. By observing a new volume of observational parameter space, they are also likely to discover unexpected phenomena. This Review traces the evolution of extragalactic radio continuum surveys from the earliest days of radio astronomy to the present, and identifies the challenges that must be overcome to achieve this transformational change.

  7. Computed bound and continuum electronic states of the nitrogen molecule

    Directory of Open Access Journals (Sweden)

    Tennyson Jonathan

    2015-01-01

    Full Text Available The dissociative recombination (DR of N2+ is important for processes occurring in our atmosphere. However, it is not particularly well characterised, experimentally for the vibrational ground state and, theoretically for the v ≥ 4. We use the R-matrix method to compute potential energy curves for both the bound Rydberg states of nitrogen and for quasi-bound states lying in the continuum. Use of a fine mesh of internuclear separations allows the details of avoided crossings to be determined. The prospects for using the curves as the input for DR calculations is discussed.

  8. Distribution of resonance widths and dynamics of continuum coupling.

    Science.gov (United States)

    Celardo, G L; Auerbach, N; Izrailev, F M; Zelevinsky, V G

    2011-01-28

    We analyze the statistics of resonance widths in a many-body Fermi system with open decay channels. Depending on the strength of continuum coupling, such a system reveals growing deviations from the standard chi-square (Porter-Thomas) width distribution. The deviations emerge from the process of increasing interaction of intrinsic states through common decay channels; in the limit of perfect coupling this process leads to the superradiance phase transition. The width distribution depends also on the intrinsic dynamics (chaotic versus regular). The results presented here are important for understanding the recent experimental data concerning the width distribution for neutron resonances in nuclei.

  9. Continuum excitations in neutron-rich Oxygen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Aumann, T.; Boretzky, K.; Cortina, D.; Cub, J.; Emling, H.; Geissel, H.; Hellstroem, M.; Holzmann, R.; Ilievski, S.; Iwasa, N.; Kaspar, M.; Kleinboehl, A.; Leifels, Y.; Muenzenberg, G.; Rejmund, M.; Scheidenberger, C.; Schlegel, C.; Suemmerer, K.; Wan, S. [Gesellschaft fuer Schwerionenforschung (GSI), Planckstr. 1, D-64291 Darmstadt (Germany); Aumann, T.; Boretzky, K.; Dostal, W.; Eberlein, B.; Kratz, J.V. [Institut fuer Kernchemie, Johannes Gutenberg Universitaet, D-55099 Mainz (Germany); Leistenschneider, A.; Elze, T.W.; Gruenschloss, A.; Stroth, J. [Institut fuer Kernphysik, Johann Wolfgang Goethe Universitaet, D-60486 Frankfurt (Germany); Cub, J.; Simon, H. [Institut fuer Kernphysik, Technische Universitaet, D-64289 Darmstadt (Germany); Holeczek, J. [Instytut Fizyki, Uniwersytet Slaski, PL-40-007 Katowice (Poland); Kulessa, R.; Lubkiewicz, E.; Wajda, E.; Walus, W. [Instytut Fizyki, Uniwersytet Jagellonski, PL-30-059 Krakow (Poland); Reiter, P. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    1998-12-01

    Electromagnetic and nuclear excitations of the neutron-rich Oxygen isotopes ranging from A=17 to A=22 are studied experimentally in reactions at energies around 600 MeV/u. By measuring the four-momenta of all decay products the excitation energy is determined. From the differential cross sections for electromagnetic excitation, the E1-strength distributions can be deduced. For {sup 18,20,22}O, low-lying dipole strength is observed, exhausting about 5{percent} of the energy weighted TRK sumrule for energies up to 5 MeV above the continuum threshold. {copyright} {ital 1998 American Institute of Physics.}

  10. Continuum effects in neutron-drip-line oxygen isotopes

    OpenAIRE

    Fossez, K.; Rotureau, J.; Michel, N.; Nazarewicz, W.

    2017-01-01

    The binding-energy pattern along the neutron-rich oxygen chain, governed by an interplay between shell effects and many-body correlations impacted by strong couplings to one- and two-neutron continuum, make these isotopes a unique testing ground for nuclear models. In this work, we investigate ground states and low-lying excited states of $^{23-28}$O using the complex-energy Gamow Shell Model and Density Matrix Renormalization Group method with a finite-range two-body interaction optimized to...

  11. Numerical simulation of asphalt mixtures fracture using continuum models

    Science.gov (United States)

    Szydłowski, Cezary; Górski, Jarosław; Stienss, Marcin; Smakosz, Łukasz

    2018-01-01

    The paper considers numerical models of fracture processes of semi-circular asphalt mixture specimens subjected to three-point bending. Parameter calibration of the asphalt mixture constitutive models requires advanced, complex experimental test procedures. The highly non-homogeneous material is numerically modelled by a quasi-continuum model. The computational parameters are averaged data of the components, i.e. asphalt, aggregate and the air voids composing the material. The model directly captures random nature of material parameters and aggregate distribution in specimens. Initial results of the analysis are presented here.

  12. Predicted continuum spectra of type II supernovae - LTE results

    Science.gov (United States)

    Shaviv, G.; Wehrse, R.; Wagoner, R. V.

    1985-01-01

    The continuum spectral energy distribution of the flux emerging from type II supernovae is calculated from quasi-static radiative transfer through a power-law density gradient, assuming radiative equilibrium and LTE. It is found that the Balmer jump disappears at high effective temperatures and low densities, while the spectrum resembles that of a dilute blackbody but is flatter with a sharper cutoff at the short-wavelength end. A significant UV excess is found in all models calculated. The calculation should be considered exploratory because of significant effects which are anticipated to arise from departure from LTE.

  13. Z Camelopardalis - Outburst P Cygni profiles and quiescent continuum

    Science.gov (United States)

    Szkody, P.; Mateo, M.

    1986-01-01

    The first orbital study of the C IV P Cygni profile in the dwarf nova Z Cam, a system of intermediate inclination. A modulation of the absorption equivalent width is apparent, with phases suggesting an effect from the mass-transfer stream. Over the outburst cycle, the strength of the P Cygni absorption and emission components is greater after outburst than during the standstill configuration, while the terminal velocities and central absorption wavelengths are similar. The continuum flux distributions during the decline from outburst and during quiescence are discussed.

  14. Ipertensione arteriosa, continuum cardiovascolare e ruolo clinico dei sartanii

    Directory of Open Access Journals (Sweden)

    Maurizio Destro

    2011-03-01

    Full Text Available The cardiovascular and cardiorenal continuum comprises the transition from cardiovascular risk factors to endothelial dysfunction and atherosclerosis, to chronic congestive heart failure, and-stage renal disease or premature death. RAAS (renin-angiotensin-aldosterone system is involved in all steps along this pathway. Data from clinical studies involving valsartan and other ARBs provide evidence of the reduction of risk of cardiovascular events, and end-organ damage in the heart, kidneys and brain. This paper summarizes the status on research of ARBs based on clinical trials and regulatory approval.

  15. NREL Leads Energy Systems Integration, Continuum Magazine: Issue 4 (Book)

    Energy Technology Data Exchange (ETDEWEB)

    2013-04-01

    Continuum Magazine showcases NREL's latest and most impactful clean energy innovations. This issue, 'NREL Leads Energy Systems Integration' explores the discipline of energy systems integration, in particular the role of the laboratory's new, one-of-a-kind Energy System Integration Facility. NREL scientists, engineers, and analysts deeply understand the fundamental science and technologies underpinning major energy producing and consuming systems, as well as the transmission infrastructure and communications and data networks required to integrate energy systems at all scales.

  16. A 3D Orthotropic Elastic Continuum Damage Material Model

    Energy Technology Data Exchange (ETDEWEB)

    English, Shawn Allen [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Brown, Arthur A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2013-08-01

    A three dimensional orthotropic elastic constitutive model with continuum damage is implemented for polymer matrix composite lamina. Damage evolves based on a quadratic homogeneous function of thermodynamic forces in the orthotropic planes. A small strain formulation is used to assess damage. In order to account for large deformations, a Kirchhoff material formulation is implemented and coded for numerical simulation in Sandia’s Sierra Finite Element code suite. The theoretical formulation is described in detail. An example of material parameter determination is given and an example is presented.

  17. From cells to tissue: A continuum model of epithelial mechanics

    Science.gov (United States)

    Ishihara, Shuji; Marcq, Philippe; Sugimura, Kaoru

    2017-08-01

    A two-dimensional continuum model of epithelial tissue mechanics was formulated using cellular-level mechanical ingredients and cell morphogenetic processes, including cellular shape changes and cellular rearrangements. This model incorporates stress and deformation tensors, which can be compared with experimental data. Focusing on the interplay between cell shape changes and cell rearrangements, we elucidated dynamical behavior underlying passive relaxation, active contraction-elongation, and tissue shear flow, including a mechanism for contraction-elongation, whereby tissue flows perpendicularly to the axis of cell elongation. This study provides an integrated scheme for the understanding of the orchestration of morphogenetic processes in individual cells to achieve epithelial tissue morphogenesis.

  18. From discrete elements to continuum fields: Extension to bidisperse systems

    Science.gov (United States)

    Tunuguntla, Deepak R.; Thornton, Anthony R.; Weinhart, Thomas

    2016-07-01

    Micro-macro transition methods can be used to, both, calibrate and validate continuum models from discrete data obtained via experiments or simulations. These methods generate continuum fields such as density, momentum, stress, etc., from discrete data, i.e. positions, velocity, orientations and forces of individual elements. Performing this micro-macro transition step is especially challenging for non-uniform or dynamic situations. Here, we present a general method of performing this transition, but for simplicity we will restrict our attention to two-component scenarios. The mapping technique, presented here, is an extension to the micro-macro transition method, called coarse-graining, for unsteady two-component flows and can be easily extended to multi-component systems without any loss of generality. This novel method is advantageous; because, by construction the obtained macroscopic fields are consistent with the continuum equations of mass, momentum and energy balance. Additionally, boundary interaction forces can be taken into account in a self-consistent way and thus allow for the construction of continuous stress fields even within one element radius of the boundaries. Similarly, stress and drag forces can also be determined for individual constituents of a multi-component mixture, which is critical for several continuum applications, e.g. mixture theory-based segregation models. Moreover, the method does not require ensemble-averaging and thus can be efficiently exploited to investigate static, steady and time-dependent flows. The method presented in this paper is valid for any discrete data, e.g. particle simulations, molecular dynamics, experimental data, etc.; however, for the purpose of illustration we consider data generated from discrete particle simulations of bidisperse granular mixtures flowing over rough inclined channels. We show how to practically use our coarse-graining extension for both steady and unsteady flows using our open-source coarse

  19. Geometry of the Shannon mutual information in continuum QFT

    Science.gov (United States)

    Junior, David R.; Oxman, Luis E.

    2017-06-01

    We analyze geometric terms and scaling properties of the Shannon mutual information in the continuum. This is done for a free massless scalar field theory in d -dimensions, in a coherent state reduced with respect to a general differentiable manifold. As a by-product, we find an expression for the reduced probability density of finding a certain field on a ball. We will also introduce and compute the Fisher information that this probability carries about the location of the observation region. This is an interesting information measure that refers to points in physical space, although in relativistic quantum field theory they are labels and not fluctuating quantum observables.

  20. Lessons in redesigning a quality program across the continuum.

    Science.gov (United States)

    Brown, Diane Storer; Church, Lauri; Heywood, Terry; Hills, John F; McCarthy, Sarah; Serway, Cindy

    2003-01-01

    The Kaiser Permanente North East Bay service area redesigned its quality program beginning in 1995, to better mirror how care was provided across the continuum. The old model had evolved over time, was based on departmental structure, and did not focus on all patient populations. The purpose of this article is to describe the redesign process, the quality model implemented, and future directions, with the hope that the lessons learned will provide other healthcare quality professionals some of the knowledge needed and, perhaps, the courage to "design" their quality programs.

  1. Affective Bipolar Disorder and Borderline Personality Disorder - Comorbidity or Continuum

    Directory of Open Access Journals (Sweden)

    Berta Ferreira

    2014-10-01

    Full Text Available The association between bipolar disorder and borderline personality has been studied by several researchers. Comorbidity has been emphasized by some authors which observe a prognostic impairment of bipolar disorder because the delay of the diagnostic. Symptoms related with alcohol and drugs abuse, suicidary behaviour and impulsivity, often present in borderline patients, make the treatment difficult. Other authors consider these symptoms as being part of the bipolar disease, proposing a continuum between the two entities. In this case, borderline personality would be a mild form of an affective disorder. We will discuss different opinions and their cli- nical and therapeutic consequences.

  2. Hybrid molecular–continuum methods: From prototypes to coupling software

    KAUST Repository

    Neumann, Philipp

    2014-02-01

    In this contribution, we review software requirements in hybrid molecular-continuum simulations. For this purpose, we analyze a prototype implementation which combines two frameworks-the Molecular Dynamics framework MarDyn and the framework Peano for spatially adaptive mesh-based simulations-and point out particular challenges of a general coupling software. Based on this analysis, we discuss the software design of our recently published coupling tool. We explain details on its overall structure and show how the challenges that arise in respective couplings are resolved by the software. © 2013 Elsevier Ltd. All rights reserved.

  3. Observations of the Solar Continuum Radio Emission at Decameter Wavelengths

    Science.gov (United States)

    Brazhenko, Anatoliy I.; Mel'Nik, Valentin N.; Konovalenko, Alexander A.; Abranin, Edward P.; Dorovskyy, Vladimir V.; Vashchishin, Rostislav V.; Frantzusenko, Anatoly V.; Rucker, Helmut O.

    2010-01-01

    Results of study of the continuum radio emission of the Sun in the decameter range are presented. Observations were carried out with radio telescope URAN-2 in summer months in 2008-2009. Radio fluxes at frequencies 20 MHz and 25 MHz in frequency band 250 kHz were obtained during the time, when there were no active regions on the solar disk. Their average values for two years were 670 Jy and 850 Jy at frequencies 20 MHz and 25 MHz correspondingly. These fluxes are in agreement with high frequency values.

  4. Wisconsin's Forests 2009

    Science.gov (United States)

    Charles H. Perry; Vern A. Everson; Brett J. Butler; Susan J. Crocker; Sally E. Dahir; Andrea L. Diss-Torrance; Grant M Domke; Dale D. Gormanson; Sarah K. Herrick; Steven S. Hubbard; Terry R. Mace; Patrick D. Miles; Mark D. Nelson; Richard B. Rodeout; Luke T. Saunders; Kirk M. Stueve; Barry T. Wilson; Christopher W. Woodall

    2012-01-01

    The second full annual inventory of Wisconsin's forests reports more than 16.7 million acres of forest land with an average volume of more than 1,400 cubic feet per acre. Forest land is dominated by the oak/hickory forest-type group, which occupies slightly more than one quarter of the total forest land area; the maple/beech/birch forest-type group occupies an...

  5. Indiana's Forests 2008

    Science.gov (United States)

    Christopher W. Woodall; Mark N. Webb; Barry T. Wilson; Jeff Settle; Ron J. Piva; Charles H. Perry; Dacia M. Meneguzzo; Susan J. Crocker; Brett J. Butler; Mark Hansen; Mark Hatfield; Gary Brand; Charles. Barnett

    2011-01-01

    The second full annual inventory of Indiana's forests reports more than 4.75 million acres of forest land with an average volume of more than 2,000 cubic feet per acre. Forest land is dominated by the white oak/red oak/hickory forest type, which occupies nearly a third of the total forest land area. Seventy-six percent of forest land consists of sawtimber, 16...

  6. Vermont's Forests 2007

    Science.gov (United States)

    Randall S. Morin; Chuck J. Barnett; Gary J. Brand; Brett J. Butler; Robert De Geus; Mark H. Hansen; Mark A. Hatfield; Cassandra M. Kurtz; W. Keith Moser; Charles H. Perry; Ron Piva; Rachel Riemann; Richard Widmann; Sandy Wilmot; Chris W. Woodall

    2011-01-01

    The first full annual inventory of Vermont's forests reports more than 4.5 million acres of forest land with an average volume of more than 2,200 cubic feet per acre. Forest land is dominated by the maple/beech/birch forest-type group, which occupies 70 percent of total forest land area. Sixty-three percent of forest land consists of large-diameter trees, 27...

  7. New Hampshire's Forests 2007

    Science.gov (United States)

    Randall S. Morin; Chuck J. Barnett; Gary J. Brand; Brett J. Butler; Grant M. Domke; Susan Francher; Mark H. Hansen; Mark A. Hatfield; Cassandra M. Kurtz; W. Keith Moser; Charles H. Perry; Ron Piva; Rachel Riemann; Chris W. Woodall

    2011-01-01

    The first full annual inventory of New Hampshire's forests reports nearly 4.8 million acres of forest land with an average volume of nearly 2,200 cubic feet per acre. Forest land is dominated by the maple/beech/birch forest-type group, which occupies 53 percent of total forest land area. Fifty-seven percent of forest land consists of large-diameter trees, 32...

  8. Coupling of nonlocal and local continuum models by the Arlequinapproach

    KAUST Repository

    Han, Fei

    2011-08-09

    The objective of this work is to develop and apply the Arlequin framework to couple nonlocal and local continuum mechanical models. A mechanically-based model of nonlocal elasticity, which involves both contact and long-range forces, is used for the \\'fine scale\\' description in which nonlocal interactions are considered to have non-negligible effects. Classical continuum mechanics only involving local contact forces is introduced for the rest of the structure where these nonlocal effects can be neglected. Both models overlap in a coupling subdomain called the \\'gluing area\\' in which the total energy is separated into nonlocal and local contributions by complementary weight functions. A weak compatibility is ensured between kinematics of both models using Lagrange multipliers over the gluing area. The discrete formulation of this specific Arlequin coupling framework is derived and fully described. The validity and limits of the technique are demonstrated through two-dimensional numerical applications and results are compared against those of the fully nonlocal elasticity method. © 2011 John Wiley & Sons, Ltd.

  9. A continuum damage model for delaminations in laminated composites

    Science.gov (United States)

    Zou, Z.; Reid, S. R.; Li, S.

    2003-02-01

    Delamination, a typical mode of interfacial damage in laminated composites, has been considered in the context of continuum damage mechanics in this paper. Interfaces where delaminations could occur are introduced between the constituent layers. A simple but appropriate continuum damage representation is proposed. A single scalar damage parameter is employed and the degradation of the interface stiffness is established. Use has been made of the concept of a damage surface to derive the damage evolution law. The damage surface is constructed so that it combines the conventional stress-based and fracture-mechanics-based failure criteria which take account of mode interaction in mixed-mode delamination problems. The damage surface shrinks as damage develops and leads to a softening interfacial constitutive law. By adjusting the shrinkage rate of the damage surface, various interfacial constitutive laws found in the literature can be reproduced. An incremental interfacial constitutive law is also derived for use in damage analysis of laminated composites, which is a non-linear problem in nature. Numerical predictions for problems involving a DCB specimen under pure mode I delamination and mixed-mode delamination in a split beam are in good agreement with available experimental data or analytical solutions. The model has also been applied to the prediction of the failure strength of overlap ply-blocking specimens. The results have been compared with available experimental and alternative theoretical ones and discussed fully.

  10. Transitioning a unidirectional composite computer model from mesoscale to continuum

    Directory of Open Access Journals (Sweden)

    Chocron Sidney

    2015-01-01

    Full Text Available Ballistic impact on composites has been a challenging problem as seen in the abundant literature about the subject. Continuum models usually cannot properly predict deflection history on the back of the target while at the same time giving reasonable ballistic limits. According to the authors the main reason is that, while continuum models are very good at reproducing the elastic characteristics of the laminate, the models do not capture the behaviour of the “failed” material. A “failed” composite can still be very effective in stopping a projectile, because it can behave very similar to a dry woven fabric. The failure aspect is much easier to capture realistically with a mesoscale model. These models explicitly contain yarns and matrix allowing the matrix to fail while the yarns stay intact and continue to offer resistance to the projectile. This paper summarizes the work performed by the authors on the computationally expensive mesoscale models and, using them as benchmark computations, describes the first steps towards obtaining more computationally effective models that still keep the right physics of the impact.

  11. State stability analysis for the fermionic projector in the continuum

    Energy Technology Data Exchange (ETDEWEB)

    Hoch, Stefan Ludwig

    2008-07-01

    The principle of the fermionic projector in the continuum gives an indication that there might be a deeper reason why elementary particles only appear with a few definite masses. In this thesis the existence of approximately state-stable configurations is shown. In order to achieve that, we make use of a variational principle for the fermionic projector in the continuum which contains certain contributions supported on the light cone. In a certain sense, these extra terms contain the structure of the underlying discrete spacetime. Lorentz invariant distributions and their convolutions are studied. Some of these are well-defined because the convolution integrals have compactly supported integrands. Other convolutions can be regularized such that the property of being ill-defined only plays a role on the light cone. These results are used to analyze the variational principle and to give criteria for state stability, which can be numerically analyzed. Some plots are presented to allow a decision about state stability and to show how possible configurations could look like. (orig.)

  12. Fractal continuum model for tracer transport in a porous medium.

    Science.gov (United States)

    Herrera-Hernández, E C; Coronado, M; Hernández-Coronado, H

    2013-12-01

    A model based on the fractal continuum approach is proposed to describe tracer transport in fractal porous media. The original approach has been extended to treat tracer transport and to include systems with radial and uniform flow, which are cases of interest in geoscience. The models involve advection due to the fluid motion in the fractal continuum and dispersion whose mathematical expression is taken from percolation theory. The resulting advective-dispersive equations are numerically solved for continuous and for pulse tracer injection. The tracer profile and the tracer breakthrough curve are evaluated and analyzed in terms of the fractal parameters. It has been found in this work that anomalous transport frequently appears, and a condition on the fractal parameter values to predict when sub- or superdiffusion might be expected has been obtained. The fingerprints of fractality on the tracer breakthrough curve in the explored parameter window consist of an early tracer breakthrough and long tail curves for the spherical and uniform flow cases, and symmetric short tailed curves for the radial flow case.

  13. A continuum of care model for postpartum hemorrhage.

    Science.gov (United States)

    Geller, Stacie E; Adams, Marci G; Miller, Suellen

    2007-01-01

    The leading cause of maternal mortality is hemorrhage, generally occurring in the postpartum period. Current levels of PPH-related morbidity and mortality in low-resource settings result from institutional, environmental, cultural and social barriers to providing skilled care and preventing, diagnosing and treating PPH. Conventional uterotonics to prevent PPH are typically not available or practical for use in low-resource settings. In such deliveries, most often taking place at home or in rural health centers, underestimation of blood loss leads to a delay in diagnosis. Deficiencies in communication and transportation infrastructure impede transfer to a higher level of care. Inability to stabilize a patient who is in hemorrhagic shock rapidly results in death. To address these individual factors, we propose a continuum of care model for PPH, including routine use of prophylactic misoprostol or other appropriate uterotonic, a standardized means of blood loss assessment, availability of a non-pneumatic anti-shock garment, and systemization of communication, transportation, and referral. Such a multifaceted, systematic, contextualized PPH continuum of care approach may have the greatest impact for saving women's lives. This model should be developed and tested to be region-specific.

  14. Health Communication and the HIV Continuum of Care.

    Science.gov (United States)

    Vermund, Sten H; Mallalieu, Elizabeth C; Van Lith, Lynn M; Struthers, Helen E

    2017-01-01

    Health communication is a broad term that applies to the fundamental need for practitioners, policy makers, patients, and community members to understand one another around health promotion and health care issues. Whether in a consultation between nurse and patient, a health clinic director's engagement with the health ministry, or a community campaign for encouraging HIV testing, all have critical health communication elements. When people's needs are not perceived by them to be addressed or clients/patients do not understand what is being communicated, they are unmotivated to engage. Health communication may be deployed at multiple levels to encourage positive behavior change and affect HIV treatment outcomes. As countries move to treatment for all as soon as possible after testing, health communication can help address significant losses at each stage of the HIV continuum of care, thereby contributing to achieving the 90-90-90 global treatment goals. This JAIDS supplement presents compelling studies that are anchored on the health communication exigencies in highly diverse HIV and AIDS contexts in low and middle income settings. Our special focus is health communication needs and challenges within the HIV continuum of care. We introduce the supplement with thumbnails summaries of the work presented by an experienced array of public health, behavioral, and clinical scientists.

  15. Evolving Human Alteration of the Carbon Cycle: the Watershed Continuum

    Science.gov (United States)

    Kaushal, S.; Delaney Newcomb, K.; Newcomer Johnson, T.; Pennino, M. J.; Smith, R. M.; Beaulieu, J. J.; Belt, K.; Grese, M.; Blomquist, J.; Duan, S.; Findlay, S.; Likens, G.; Mayer, P. M.; Murthy, S.; Utz, R.; Yepsen, M.

    2014-12-01

    Watersheds experiencing land development are constantly evolving, and their biogeochemical signatures are expected to evolve across both space and time in drainage waters. We investigate how land development influences spatial and temporal evolution of the carbon cycle from small streams to major rivers in the Eastern U.S. Along the watershed continuum, we show that there is spatial evolution in: (1) the amount, chemical form, and bioavailability of carbon; (2) carbon retention/release at the reach scale; and (3) ecosystem metabolism of carbon from headwaters to coastal waters. Over shorter time scales, the interaction between land use and climate variability alters magnitude and frequency of carbon "pulses" in watersheds. Amounts and forms of carbon pulses in agricultural and urban watersheds respond similarly to climate variability due to headwater alteration and loss of ecosystem services to buffer runoff and temperature changes. Over longer time scales, land use change has altered organic carbon concentrations in tidal waters of Chesapeake Bay, and there have been increased bicarbonate alkalinity concentrations in rivers throughout the Eastern U.S. due to human activities. In summary, our analyses indicates that the form and reactivity of carbon have evolved over space and time along the watershed continuum with major implications for downstream ecosystem metabolism, biological oxygen demand, carbon dioxide production, and river alkalinization.

  16. Variational principles of continuum mechanics. Vol. 2. Applications

    Energy Technology Data Exchange (ETDEWEB)

    Berdichevsky, Victor L. [Wayne State Univ., Detroit, MI (United States). Dept. of Mechanical Engineering

    2009-07-01

    The book reviews the two features of the variational approach: its use as a universal tool to describe physical phenomena and as a source for qualitative and quantitative methods of studying particular problems. Berdichevsky's work differs from other books on the subject in focusing mostly on the physical origin of variational principles as well as establishing their interrelations. For example, the Gibbs principles appear as a consequence of the Einstein formula for thermodynamic fluctuations rather than as the first principles of the theory of thermodynamic equilibrium. Mathematical issues are considered as long as they shed light on the physical outcomes and/or provide a useful technique for the direct study of variational problems. In addition, a thorough account of variational principles discovered in various branches of continuum mechanics is given. This book, the second volume, describes how the variational approach can be applied to constructing models of continuum media, such as the theory of elastic plates; shells and beams; shallow water theory; heterogeneous mixtures; granular materials; and turbulence. It goes on to apply the variational approach to asymptotical analysis of problems with small parameters, such as the derivation of the theory of elastic plates, shells and beams from three-dimensional elasticity theory; and the basics of homogenization theory. A theory of stochastic variational problems is considered in detail too, along with applications to the homogenization of continua with random microstructures. (orig.)

  17. Asteroid-comet continuum objects in the solar system.

    Science.gov (United States)

    Hsieh, Henry H

    2017-07-13

    In this review presented at the Royal Society meeting, 'Cometary science after Rosetta', I present an overview of studies of small solar system objects that exhibit properties of both asteroids and comets (with a focus on so-called active asteroids). Sometimes referred to as 'transition objects', these bodies are perhaps more appropriately described as 'continuum objects', to reflect the notion that rather than necessarily representing actual transitional evolutionary states between asteroids and comets, they simply belong to the general population of small solar system bodies that happen to exhibit a continuous range of observational, physical and dynamical properties. Continuum objects are intriguing because they possess many of the properties that make classical comets interesting to study (e.g. relatively primitive compositions, ejection of surface and subsurface material into space where it can be more easily studied, and orbital properties that allow us to sample material from distant parts of the solar system that would otherwise be inaccessible), while allowing us to study regions of the solar system that are not sampled by classical comets.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Author(s).

  18. Microscopic and continuum descriptions of Janus motor fluid flow fields

    Science.gov (United States)

    Reigh, Shang Yik; Schofield, Jeremy; Kapral, Raymond

    2016-01-01

    Active media, whose constituents are able to move autonomously, display novel features that differ from those of equilibrium systems. In addition to naturally occurring active systems such as populations of swimming bacteria, active systems of synthetic self-propelled nanomotors have been developed. These synthetic systems are interesting because of their potential applications in a variety of fields. Janus particles, synthetic motors of spherical geometry with one hemisphere that catalyses the conversion of fuel to product and one non-catalytic hemisphere, can propel themselves in solution by self-diffusiophoresis. In this mechanism, the concentration gradient generated by the asymmetric catalytic activity leads to a force on the motor that induces fluid flows in the surrounding medium. These fluid flows are studied in detail through microscopic simulations of Janus motor motion and continuum theory. It is shown that continuum theory is able to capture many, but not all, features of the dynamics of the Janus motor and the velocity fields of the fluid. This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’. PMID:27698037

  19. Multi Texture Analysis of Colorectal Cancer Continuum Using Multispectral Imagery.

    Directory of Open Access Journals (Sweden)

    Ahmad Chaddad

    Full Text Available This paper proposes to characterize the continuum of colorectal cancer (CRC using multiple texture features extracted from multispectral optical microscopy images. Three types of pathological tissues (PT are considered: benign hyperplasia, intraepithelial neoplasia and carcinoma.In the proposed approach, the region of interest containing PT is first extracted from multispectral images using active contour segmentation. This region is then encoded using texture features based on the Laplacian-of-Gaussian (LoG filter, discrete wavelets (DW and gray level co-occurrence matrices (GLCM. To assess the significance of textural differences between PT types, a statistical analysis based on the Kruskal-Wallis test is performed. The usefulness of texture features is then evaluated quantitatively in terms of their ability to predict PT types using various classifier models.Preliminary results show significant texture differences between PT types, for all texture features (p-value < 0.01. Individually, GLCM texture features outperform LoG and DW features in terms of PT type prediction. However, a higher performance can be achieved by combining all texture features, resulting in a mean classification accuracy of 98.92%, sensitivity of 98.12%, and specificity of 99.67%.These results demonstrate the efficiency and effectiveness of combining multiple texture features for characterizing the continuum of CRC and discriminating between pathological tissues in multispectral images.

  20. VCMM: a visual tool for continuum molecular modeling.

    Science.gov (United States)

    Bai, Shiyang; Lu, Benzhuo

    2014-05-01

    This paper describes the design and function of a visualization tool, VCMM, for visualizing and analyzing data, and interfacing solvers for generic continuum molecular modeling. In particular, an emphasis of the program is to treat the data set based on unstructured mesh as used in finite/boundary element simulations, which largely enhances the capabilities of current visualization tools in this area that only support structured mesh. VCMM is segmented into molecular, meshing and numerical modules. The capabilities of molecular module include molecular visualization and force field assignment. Meshing module contains mesh generation, analysis and visualization tools. Numerical module currently provides a few finite/boundary element solvers of continuum molecular modeling, and contains several common visualization tools for the numerical result such as line and plane interpolations, surface probing, volume rendering and stream rendering. Three modules can exchange data with each other and carry out a complete process of modeling. Interfaces are also designed in order to facilitate usage of other mesh generation tools and numerical solvers. We develop a technique to accelerate data retrieval and have combined many graphical techniques in visualization. VCMM is highly extensible, and users can obtain more powerful functions by introducing relevant plug-ins. VCMM can also be useful in other fields such as computational quantum chemistry, image processing, and material science. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Asteroid-comet continuum objects in the solar system

    Science.gov (United States)

    Hsieh, Henry H.

    2017-05-01

    In this review presented at the Royal Society meeting, `Cometary science after Rosetta', I present an overview of studies of small solar system objects that exhibit properties of both asteroids and comets (with a focus on so-called active asteroids). Sometimes referred to as `transition objects', these bodies are perhaps more appropriately described as `continuum objects', to reflect the notion that rather than necessarily representing actual transitional evolutionary states between asteroids and comets, they simply belong to the general population of small solar system bodies that happen to exhibit a continuous range of observational, physical and dynamical properties. Continuum objects are intriguing because they possess many of the properties that make classical comets interesting to study (e.g. relatively primitive compositions, ejection of surface and subsurface material into space where it can be more easily studied, and orbital properties that allow us to sample material from distant parts of the solar system that would otherwise be inaccessible), while allowing us to study regions of the solar system that are not sampled by classical comets. This article is part of the themed issue 'Cometary science after Rosetta'.

  2. Morphing continuum theory for turbulence: Theory, computation, and visualization

    Science.gov (United States)

    Chen, James

    2017-10-01

    A high order morphing continuum theory (MCT) is introduced to model highly compressible turbulence. The theory is formulated under the rigorous framework of rational continuum mechanics. A set of linear constitutive equations and balance laws are deduced and presented from the Coleman-Noll procedure and Onsager's reciprocal relations. The governing equations are then arranged in conservation form and solved through the finite volume method with a second-order Lax-Friedrichs scheme for shock preservation. A numerical example of transonic flow over a three-dimensional bump is presented using MCT and the finite volume method. The comparison shows that MCT-based direct numerical simulation (DNS) provides a better prediction than Navier-Stokes (NS)-based DNS with less than 10% of the mesh number when compared with experiments. A MCT-based and frame-indifferent Q criterion is also derived to show the coherent eddy structure of the downstream turbulence in the numerical example. It should be emphasized that unlike the NS-based Q criterion, the MCT-based Q criterion is objective without the limitation of Galilean invariance.

  3. Microscopic and continuum descriptions of Janus motor fluid flow fields

    Science.gov (United States)

    Reigh, Shang Yik; Huang, Mu-Jie; Schofield, Jeremy; Kapral, Raymond

    2016-11-01

    Active media, whose constituents are able to move autonomously, display novel features that differ from those of equilibrium systems. In addition to naturally occurring active systems such as populations of swimming bacteria, active systems of synthetic self-propelled nanomotors have been developed. These synthetic systems are interesting because of their potential applications in a variety of fields. Janus particles, synthetic motors of spherical geometry with one hemisphere that catalyses the conversion of fuel to product and one non-catalytic hemisphere, can propel themselves in solution by self-diffusiophoresis. In this mechanism, the concentration gradient generated by the asymmetric catalytic activity leads to a force on the motor that induces fluid flows in the surrounding medium. These fluid flows are studied in detail through microscopic simulations of Janus motor motion and continuum theory. It is shown that continuum theory is able to capture many, but not all, features of the dynamics of the Janus motor and the velocity fields of the fluid. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  4. A continuum model for dynamic analysis of the Space Station

    Science.gov (United States)

    Thomas, Segun

    1989-01-01

    Dynamic analysis of the International Space Station using MSC/NASTRAN had 1312 rod elements, 62 beam elements, 489 nodes and 1473 dynamic degrees of freedom. A realtime, man-in-the-loop simulation of such a model is impractical. This paper discusses the mathematical model for realtime dynamic simulation of the Space Station. Several key questions in structures and structural dynamics are addressed. First, to achieve a significant reduction in the number of dynamic degrees of freedom, a continuum equivalent representation of the Space Station truss structure which accounted for the unsymmetry of the basic configuration and resulted in the coupling of extensional and transverse deformation, is developed. Next, dynamic equations for the continuum equivalent of the Space Station truss structure are formulated using a matrix version of Kane's dynamical equations. Flexibility is accounted for by using a theory that accommodates extension, bending in two principal planes and shear displacement. Finally, constraint equations suitable for dynamic analysis of flexible bodies with closed loop configuration are developed and solution of the resulting system of equations is based on the zero eigenvalue theorem.

  5. Light vector mesons and the dielectron continuum in PHENIX

    Directory of Open Access Journals (Sweden)

    Campbell Sarah

    2012-11-01

    Full Text Available The PHENIX experiment at RHIC has measured the dielectron continuum and the ω and ϕ light vector mesons using hadronic and dielectron decay channels in √sNN = 200 GeV p+p, d+Au, Cu+Cu and Au+Au collisions. The ω and ϕ mesons experience no strong cold nuclear matter effects but in central heavy ion collisions their yields are suppressed at high pT, extending to intermediate pT for the ϕ. The comparison of the ω and ϕ suppression to the suppression of other hadrons suggests parton energy loss for high pT mesons and favors a recombination production mechanism for intermediate pT ϕ mesons. The dielectron continuum shows a low mass excess in central Au+Au and Cu+Cu collisions while the p+p and d+Au spectra agree with their respective cocktails. The low mass excess consists of a high pT thermal virtual photon component and a much larger low pT component.

  6. Continuum of Renin-Independent Aldosteronism in Normotension.

    Science.gov (United States)

    Baudrand, Rene; Guarda, Francisco J; Fardella, Carlos; Hundemer, Gregory; Brown, Jenifer; Williams, Gordon; Vaidya, Anand

    2017-05-01

    Primary aldosteronism is a severe form of autonomous aldosteronism. Milder forms of autonomous and renin-independent aldosteronism may be common, even in normotension. We characterized aldosterone secretion in 210 normotensives who had suppressed plasma renin activity (renin, and potassium handling were investigated. Severe autonomous aldosterone secretion that was consistent with confirmed primary aldosteronism was defined based on accepted criteria of an aldosterone excretion rate >12 μg/24 hours with urinary sodium excretion >200 mmol/24 hours. Across the population, there were strong and significant associations between higher aldosterone excretion rate and higher urinary potassium excretion, higher angiotensin II-stimulated aldosterone, and lower plasma renin activity, suggesting a continuum of renin-independent aldosteronism and mineralocorticoid receptor activity. Autonomous aldosterone secretion that fulfilled confirmatory criteria for primary aldosteronism was detected in 29 participants (14%). Normotensives with evidence suggestive of confirmed primary aldosteronism had higher 24-hour urinary aldosterone excretion rate (20.2±12.2 versus 6.2±2.9 μg/24 hours; Prenin ratio, blood pressure, or renal plasma flow between the 2 groups. These findings indicate a continuum of renin-independent aldosteronism and mineralocorticoid receptor activity in normotension that ranges from subtle to overtly dysregulated and autonomous. Longitudinal studies are needed to determine whether this spectrum of autonomous aldosterone secretion contributes to hypertension and cardiovascular disease. © 2017 American Heart Association, Inc.

  7. [Continuum, the continuing education platform based on a competency matrix].

    Science.gov (United States)

    Ochoa Sangrador, C; Villaizán Pérez, C; González de Dios, J; Hijano Bandera, F; Málaga Guerrero, S

    2016-04-01

    Competency-Based Education is a learning method that has changed the traditional teaching-based focus to a learning-based one. Students are the centre of the process, in which they must learn to learn, solve problems, and adapt to changes in their environment. The goal is to provide learning based on knowledge, skills (know-how), attitude and behaviour. These sets of knowledge are called competencies. It is essential to have a reference of the required competencies in order to identify the need for them. Their acquisition is approached through teaching modules, in which one or more skills can be acquired. This teaching strategy has been adopted by Continuum, the distance learning platform of the Spanish Paediatric Association, which has developed a competency matrix based on the Global Paediatric Education Consortium training program. In this article, a review will be presented on the basics of Competency-Based Education and how it is applied in Continuum. Copyright © 2015 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

  8. Psychostimulants and cognition: a continuum of behavioral and cognitive activation.

    Science.gov (United States)

    Wood, Suzanne; Sage, Jennifer R; Shuman, Tristan; Anagnostaras, Stephan G

    2014-01-01

    Psychostimulants such as cocaine have been used as performance enhancers throughout recorded history. Although psychostimulants are commonly prescribed to improve attention and cognition, a great deal of literature has described their ability to induce cognitive deficits, as well as addiction. How can a single drug class be known to produce both cognitive enhancement and impairment? Properties of the particular stimulant drug itself and individual differences between users have both been suggested to dictate the outcome of stimulant use. A more parsimonious alternative, which we endorse, is that dose is the critical determining factor in cognitive effects of stimulant drugs. Herein, we review several popular stimulants (cocaine, amphetamine, methylphenidate, modafinil, and caffeine), outlining their history of use, mechanism of action, and use and abuse today. One common graphic depiction of the cognitive effects of psychostimulants is an inverted U-shaped dose-effect curve. Moderate arousal is beneficial to cognition, whereas too much activation leads to cognitive impairment. In parallel to this schematic, we propose a continuum of psychostimulant activation that covers the transition from one drug effect to another as stimulant intake is increased. Low doses of stimulants effect increased arousal, attention, and cognitive enhancement; moderate doses can lead to feelings of euphoria and power, as well as addiction and cognitive impairment; and very high doses lead to psychosis and circulatory collapse. This continuum helps account for the seemingly disparate effects of stimulant drugs, with the same drug being associated with cognitive enhancement and impairment.

  9. Missing links in the root-soil organic matter continuum

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Sarah L. [Argonne National Laboratory (ANL); Iversen, Colleen M [ORNL

    2009-01-01

    The soil environment remains one of the most complex and poorly understood research frontiers in ecology. Soil organic matter (SOM), which spans a continuum from fresh detritus to highly processed, mineral-associated organic matter, is the foundation of sustainable terrestrial ecosystems. Heterogeneous SOM pools are fueled by inputs from living and dead plants, driven by the activity of micro- and mesofauna, and are shaped by a multitude of abiotic factors. The specialization required to measure unseen processes that occur on a wide range of spatial and temporal scales has led to the partitioning of soil ecology research across several disciplines. In the organized oral session 'Missing links in the root-soil organic matter continuum' at the annual Ecological Society of America meeting in Albuquerque, NM, USA, we joined the call for greater communication and collaboration among ecologists who work at the root-soil interface (e.g. Coleman, 2008). Our goal was to bridge the gap between scientific disciplines and to synthesize disconnected pieces of knowledge from root-centric and soil-centric studies into an integrated understanding of belowground ecosystem processes. We focused this report around three compelling themes that arose from the session: (1) the influence of the rhizosphere on SOM cycling, (2) the role of soil heterotrophs in driving the transformation of root detritus to SOM, and (3) the controlling influence of the soil environment on SOM dynamics. We conclude with a discussion of new approaches for gathering data to bridge gaps in the root-SOM continuum and to inform the next generation of ecosystem models. Although leaf litter has often been considered to be the main source of organic inputs to soil, Ann Russell synthesized a convincing body of work demonstrating that roots, rather than surface residues, control the accumulation of SOM in a variety of ecosystems. Living roots, which are chemically diverse and highly dynamic, also influence a

  10. Percent Forest Cover (Future)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Forests provide economic and ecological value. High percentages of forest cover (FORPCTFuture) generally indicate healthier ecosystems and cleaner surface water....

  11. Percent Forest Cover

    Data.gov (United States)

    U.S. Environmental Protection Agency — Forests provide economic and ecological value. High percentages of forest cover (FORPCT) generally indicate healthier ecosystems and cleaner surface water. More...

  12. Evolution of generalized couple-stress continuum theories: a critical analysis

    OpenAIRE

    Hadjesfandiari, Ali R.; Dargush, Gary F.

    2014-01-01

    In this paper, we examine different generalized couple-stress continuum mechanics theories, including couple stress, strain gradient and micropolar theories. First, we investigate the fundamental requirements in any consistent size-dependent couple stress continuum mechanics, for which satisfying basic rules of mathematics and mechanics are crucial to establish a consistent theory. As a result, we show that continuum couple stress theory must be based on the displacement field and its corresp...

  13. Mondrian Forests: Efficient Online Random Forests

    OpenAIRE

    Lakshminarayanan, Balaji; Roy, Daniel M.; Teh, Yee Whye

    2014-01-01

    Ensembles of randomized decision trees, usually referred to as random forests, are widely used for classification and regression tasks in machine learning and statistics. Random forests achieve competitive predictive performance and are computationally efficient to train and test, making them excellent candidates for real-world prediction tasks. The most popular random forest variants (such as Breiman's random forest and extremely randomized trees) operate on batches of training data. Online ...

  14. COMIFAC Forest Conservation Framework: Towards Better Forest ...

    African Journals Online (AJOL)

    Protected areas in Central Africa are a panacea as several million people are not schooled on the benefits of sustainably managing forests. Of perennial concern is the land tenure system which could provide incentives for forest management and conservation. Within this context, this article examines COMIFAC's forest ...

  15. Forest tenure and sustainable forest management

    Science.gov (United States)

    J.P. Siry; K. McGinley; F.W. Cubbage; P. Bettinger

    2015-01-01

    We reviewed the principles and key literature related to forest tenure and sustainable forest management, and then examined the status of sustainable forestry and land ownership at the aggregate national level for major forested countries. The institutional design principles suggested by Ostrom are well accepted for applications to public, communal, and private lands....

  16. Returning forests analyzed with the forest identity.

    Science.gov (United States)

    Kauppi, Pekka E; Ausubel, Jesse H; Fang, Jingyun; Mather, Alexander S; Sedjo, Roger A; Waggoner, Paul E

    2006-11-14

    Amid widespread reports of deforestation, some nations have nevertheless experienced transitions from deforestation to reforestation. In a causal relationship, the Forest Identity relates the carbon sequestered in forests to the changing variables of national or regional forest area, growing stock density per area, biomass per growing stock volume, and carbon concentration in the biomass. It quantifies the sources of change of a nation's forests. The Identity also logically relates the quantitative impact on forest expanse of shifting timber harvest to regions and plantations where density grows faster. Among 50 nations with extensive forests reported in the Food and Agriculture Organization's comprehensive Global Forest Resources Assessment 2005, no nation where annual per capita gross domestic product exceeded 4,600 dollars had a negative rate of growing stock change. Using the Forest Identity and national data from the Assessment report, a single synoptic chart arrays the 50 nations with coordinates of the rates of change of basic variables, reveals both clusters of nations and outliers, and suggests trends in returning forests and their attributes. The Forest Identity also could serve as a tool for setting forest goals and illuminating how national policies accelerate or retard the forest transitions that are diffusing among nations.

  17. Exploring the HIV continuum of care among young black MSM.

    Directory of Open Access Journals (Sweden)

    Lisa Hightow-Weidman

    Full Text Available HIV disproportionately impacts young, black men who have sex with men (YBMSM who experience disparities across the HIV care continuum. A more nuanced understanding of facilitators and barriers to engagement in care, missed visits, antiretroviral uptake, adherence and viral suppression could improve care and intervention design.A randomized controlled trial of an online intervention, healthMpowerment, enrolled 465 YBMSM (18-30 years; 193 identified as HIV-positive. Bivariable and multivariable analyses of baseline data explored predictors of: engagement in care, missed visits, antiretroviral uptake, self-reported adherence, and viral suppression.Mean age was 24.9 years; most identified as gay (71.0% and were receiving HIV care (89.1%. Among those in care, 52.1% reported no missed visits in the past 12 months, 41 (24.6% reported one missed visit, and 39 (23.4% reported two or more. Having insurance (prevalence odds ratio [POR] 4.5; 95% CI: 1.3, 15.8 and provider self-efficacy (POR 20.1; 95% CI: 6.1, 64.1 were associated with being in care. Those with a college degree (POR 9.1; 95% CI: 1.9, 45.2 and no recent marijuana (POR 2.6; 95% CI: 1.2, 5.6 or methamphetamine use (POR 5.4; 95% CI: 1.0, 28.5 were less likely to miss visits. Most (n = 153, 84.1% had been prescribed antiretroviral therapy. A majority of participants (70.8% reported ≥90% adherence; those with depressive symptoms had 4.7 times the odds of reporting adherence <90% (95% CI: 1.65, 13.37. Of participants who reported viral load testing in the past six months, 65% (n = 102 reported an undetectable viral load. Disclosure to sex partners was associated with viral suppression (POR 6.0; 95% CI: 1.6, 22.4.Multi-level facilitators and barriers to engagement across the continuum of care were identified in this sample of YBMSM. Understanding the distinct needs of YBMSM at each stage of the continuum and addressing them through tailored approaches is critical for long term success in care.

  18. Bacterial Biogeography across the Amazon River-Ocean Continuum

    Directory of Open Access Journals (Sweden)

    Mary Doherty

    2017-05-01

    Full Text Available Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ∼675 km of the lower Amazon River mainstem, in the Tapajós River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2–2.0 μm and >2.0 μm. River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May and low (December discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity near-shore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in

  19. Lattice Boltzmann equation method for multiple immiscible continuum fluids

    Science.gov (United States)

    Spencer, T. J.; Halliday, I.; Care, C. M.

    2010-12-01

    This paper generalizes the two-component algorithm of Sec. , extending it, in Sec. , to describe N>2 mutually immiscible fluids in the isothermal continuum regime. Each fluid has an independent interfacial tension. While retaining all its computational advantages, we remove entirely the empiricism associated with contact behavior in our previous multiple immiscible fluid models [M. M. Dupin , Phys. Rev. E 73, 055701(R) (2006)10.1103/PhysRevE.73.055701; Med. Eng. Phys. 28, 13 (2006)10.1016/j.medengphy.2005.04.015] while solidifying the physical foundations. Moreover, the model relies upon a fluid-fluid segregation which is simpler, computationally faster, more free of artifacts (i.e., the interfacial microcurrent), and upon an interface-inducing force distribution which is analytic. The method is completely symmetric between any numbers of immiscible fluids and stable over a wide range of directly input interfacial tension. We present data on the steady-state properties of multiple interface model, which are in good agreement with theory [R. E. Johnson and S. S. Sadhal, Annu. Rev. Fluid Mech. 17, 289 (1985)10.1146/annurev.fl.17.010185.001445], specifically on the shapes of multidrop systems. Section is an analysis of the kinetic and continuum-scale descriptions of the underlying two-component lattice Boltzmann model for immiscible fluids, extendable to more than two immiscible fluids. This extension requires (i) the use of a more local kinetic equation perturbation which is (ii) free from a reliance on measured interfacial curvature. It should be noted that viewed simply as a two-component method, the continuum algorithm is inferior to our previous methods, reported by Lishchuk [Phys. Rev. E 67, 036701 (2003)]10.1103/PhysRevE.76.036701 and Halliday [Phys. Rev. E 76, 026708 (2007)]10.1103/PhysRevE.76.026708. Greater stability and parameter range is achieved in multiple drop simulations by using the forced multi-relaxation-time lattice Boltzmann method developed

  20. Restoring forests

    DEFF Research Database (Denmark)

    Jacobs, Douglass F.; Oliet, Juan A.; Aronson, James

    2015-01-01

    of land requiring restoration implies the need for spatial prioritization of restoration efforts according to cost-benefit analyses that include ecological risks. To design resistant and resilient ecosystems that can adapt to emerging circumstances, an adaptive management approach is needed. Global change......, in particular, imparts a high degree of uncertainty about the future ecological and societal conditions of forest ecosystems to be restored, as well as their desired goods and services. We must also reconsider the suite of species incorporated into restoration with the aim of moving toward more stress resistant...... and competitive combinations in the longer term. Non-native species may serve an important role under some circumstances, e.g., to facilitate reintroduction of native species. Propagation and field establishment techniques must promote survival through seedling stress resistance and site preparation. An improved...

  1. Lesbian Continuum As An Alternative Strategy In Negotiating Heteronormativity In Sarah Water’s Fingersmith

    Directory of Open Access Journals (Sweden)

    Mega Hayuningtyas Erwanti

    2015-12-01

    Full Text Available This study is conducted to examine the portrayal of a lesbian continuum in Sarah Waters’ Fingersmith. To conduct the analysis, there are two research questions: first, how is the construction of lesbian continuum portrayed in the relationship between Susan Trinder and Maud Lilly and how does lesbian continuum become a strategy to negotiate compulsory heterosexuality. In doing the analysis, the theory of lesbian continuum which is proposed by Adrienne Rich will be used to elaborate the novel. This study is a qualitative research where the data are taken from the novel Fingersmith, library research, journals, and other relevant sources. To gain the comprehensive analysis, this study uses some methods which are: close reading, postulation the statements of the problems, data classification, and analysis using the lesbian continuum theory, supporting analysis through library research, books, and academic journals. This study finds that the characters of Susan Trinder and Maud Lilly can be identified as having a double life which constructs the lesbian continuum. Moreover, the lesbian continuum becomes a strategy to negotiate compulsory heterosexuality with denial and negotiation of women’s oppression. Abstrak: Artikel ini mengkaji representasi lesbian continuum dalam novel Sarah Waters yang berjudul Fingersmith. Dua pertanyaan utama penelitian ini adalah (1 bagaimana konstruksi lesbian continuum direpresentasikan dalam hubungan antara tokoh Susan Trinder dan Maud Lily dalam novel Fingersmith dan (2 bagaimana lesbian continuum menjadi strategi untuk menghadapi compulsory heterosexuality dalam novel Fingersmith. Teori lesbian continuum oleh Adrienne Rich akan menjadi teori utama untuk menjawab pertanyaan penelitian. Menggunakan teknik pembacaan novel dan analisis pustaka yang bersumber dari jurnal dan sumber lain yang mendukung. Untuk mendapatkan data yang komprehensip, metode yang dipakai adalah close reading, menjabarkan pertanyaan, klasifikasi

  2. Forest farming practices

    Science.gov (United States)

    J.L. Chamberlain; D. Mitchell; T. Brigham; T. Hobby; L. Zabek; J. Davis

    2009-01-01

    Forest farming in North America is becoming popular as a way for landowners to diversify income opportunities, improve management of forest resources, and increase biological diversity. People have been informally "farming the forests" for generations. However, in recent years, attention has been directed at formalizing forest farming and improving it...

  3. Forest Health Detectives

    Science.gov (United States)

    Bal, Tara L.

    2014-01-01

    "Forest health" is an important concept often not covered in tree, forest, insect, or fungal ecology and biology. With minimal, inexpensive equipment, students can investigate and conduct their own forest health survey to assess the percentage of trees with natural or artificial wounds or stress. Insects and diseases in the forest are…

  4. North Dakota's forests 2005

    Science.gov (United States)

    David E. Haugen; Michael Kangas; Susan J. Crocker; Charles H. Perry; Christopher W. Woodall; Brett J. Butler; Barry T. Wilson; Dan J. Kaisershot

    2009-01-01

    The first completed annual inventory of North Dakota's forests reports estimates of more than 724,000 acres of forest land. Information about forest attributes and forest health is presented along with information on agents of change including changing land use patterns and the introduction of nonnative plants, insects, and disease.

  5. Wisconsin's forests, 2004

    Science.gov (United States)

    Charles H. (Hobie) Perry; Vern A. Everson; Ian K. Brown; Jane Cummings-Carlson; Sally E. Dahir; Edward A. Jepsen; Joe Kovach; Michael D. Labissoniere; Terry R. Mace; Eunice A. Padley; Richard B. Rideout; Brett J. Butler; Susan J. Crocker; Greg C. Liknes; Randall S. Morin; Mark D. Nelson; Barry T. (Ty) Wilson; Christopher W. Woodall

    2008-01-01

    The first full, annualized inventory of Wisconsin's forests was completed in 2004 after 6,478 forested plots were visited. There are more than 16.0 million acres of forest land in the Wisconsin, nearly half of the State's land area; 15.8 million acres meet the definition of timberland. The total area of both forest land and timberland continues an upward...

  6. Restoring Forested Wetland Ecosystems

    Science.gov (United States)

    John A. Stanturf; Emile S. Gardiner; Melvin L. Warren

    2003-01-01

    Forests as natural systems are intrinsically linked to the sustainability of fresh-water systems. Efforts worldwide to restore forest ecosystems seek to counteract centuries of forest conversion to agriculture and other uses. Afforestation, the practice of regenerating forests on land deforested for agriculture or other uses, is occurring at an intense pace in the...

  7. Iowa's forest resources, 1974.

    Science.gov (United States)

    John S. Jr. Spencer; Pamela J. Jakes

    1980-01-01

    The second inventory of Iowa's forest resources shows big declines in commercial forest area and in growing-stock and sawtimber volumes between 1954 and 1974. Presented are text and statistics on forest area and timber volume, growth, mortality, ownership, stocking, future timber supply, timber use, forest management opportunities, and nontimber resources.

  8. Sustaining Urban Forests

    Science.gov (United States)

    John F. Dwyer; David J. Nowak; Mary Heather Noble

    2003-01-01

    The significance of the urban forest resource and the powerful forces for change in the urban environment make sustainability a critical issue in urban forest management. The diversity, connectedness, and dynamics of the urban forest establish the context for management that will determine the sustainability of forest structure, health, functions, and benefits. A...

  9. Oklahoma's forests, 2014

    Science.gov (United States)

    Kerry Dooley; KaDonna. Randolph

    2017-01-01

    This resource bulletin describes the principal findings of the 2014 forest inventory of Oklahoma (conducted 2009–2014) and examines changes since the previous survey of Oklahoma in 2008. Topics presented include forest area, volume, biomass, number of trees, growth, mortality, removals, forest health, silvicultural treatments, and forest ownership.

  10. Topology Optimization of Continuum Structures with Local Stress Constraints

    DEFF Research Database (Denmark)

    Duysinx, Pierre; Bendsøe, Martin P

    1998-01-01

    We introduce an extension of current technologies for topology optimization of continuum structures which allows for treating local stress criteria. We first consider relevant stress criteria for porous composite materials, initially by studying the stress states of the so-called rank 2 layered...... materials. Then, on the basis of the theoretical study of the rank 2 microstructures, we propose an empirical model, that extends the power penalized stiffness model (also called SIMP for Solid Isotropic Microstructure with Penalization for intermediate densities). In a second part, solution aspects...... of topology problems are considered. To deal with the so-called 'singularity' phenomenon of stress constraints in topology design, an epsilon-constraint relaxation of the stress constraints is used. We describe the mathematical programming approach that is used to solve the numerical optimization problems...

  11. Perspective: Polarizable continuum models for quantum-mechanical descriptions.

    Science.gov (United States)

    Lipparini, Filippo; Mennucci, Benedetta

    2016-04-28

    Polarizable continuum solvation models are nowadays the most popular approach to describe solvent effects in the context of quantum mechanical calculations. Unexpectedly, despite their widespread use in all branches of quantum chemistry and beyond, important aspects of both their theoretical formulation and numerical implementation are still not completely understood. In particular, in this perspective we focus on the numerical issues of their implementation when applied to large systems and on the theoretical framework needed to treat time dependent problems and excited states or to deal with electronic correlation. Possible extensions beyond a purely electrostatic model and generalizations to environments beyond common solvents are also critically presented and discussed. Finally, some possible new theoretical approaches and numerical strategies are suggested to overcome the obstacles which still prevent a full exploitation of these models.

  12. Perspective: Polarizable continuum models for quantum-mechanical descriptions

    Science.gov (United States)

    Lipparini, Filippo; Mennucci, Benedetta

    2016-04-01

    Polarizable continuum solvation models are nowadays the most popular approach to describe solvent effects in the context of quantum mechanical calculations. Unexpectedly, despite their widespread use in all branches of quantum chemistry and beyond, important aspects of both their theoretical formulation and numerical implementation are still not completely understood. In particular, in this perspective we focus on the numerical issues of their implementation when applied to large systems and on the theoretical framework needed to treat time dependent problems and excited states or to deal with electronic correlation. Possible extensions beyond a purely electrostatic model and generalizations to environments beyond common solvents are also critically presented and discussed. Finally, some possible new theoretical approaches and numerical strategies are suggested to overcome the obstacles which still prevent a full exploitation of these models.

  13. Prostate Cancer Disparities throughout the Cancer Control Continuum

    Directory of Open Access Journals (Sweden)

    Kyle J. Dalton

    2013-11-01

    Full Text Available Prostate cancer (PCa is the most commonly diagnosed malignancy and the second leading cause of cancer deaths among men in the United States. The American Cancer Society estimates that 238,590 U.S. men will develop PCa and 29,720 men will die from the disease in 2013. PCa exhibits the most profound racial disparities of all cancers with African American men having a 70% higher incidence rate and more than two times higher mortality rate than Caucasian men. Published research on PCa disparities focuses on singular outcomes such as incidence, mortality or quality of life. The objective of this paper is to provide a comprehensive summary of the racial disparities found at each stage of the PCa Care Continuum which includes prevention, detection, treatments, and outcomes and survival. It focuses primarily on disparities among Caucasian (white and African American men.

  14. Kinematic Analysis of Continuum Robot Consisted of Driven Flexible Rods

    Directory of Open Access Journals (Sweden)

    Yingzhong Tian

    2016-01-01

    Full Text Available This paper presents the kinematic analysis of a continuum bionic robot with three flexible actuation rods. Since the motion of the end-effector is actuated by the deformation of the rods, the robot structure is with high elasticity and good compliance and the kinematic analysis of the robot requires special treatment. We propose a kinematic model based on the geometry with constant curvature. The analysis consists of two independent mappings: a general mapping for the kinematics of all robots and a specific mapping for this kind of robots. Both of those mappings are developed for the single section and for the multisections. We aim at providing a guide for kinematic analysis of the similar manipulators through this paper.

  15. Anisotropy-induced photonic bound states in the continuum

    Science.gov (United States)

    Gomis-Bresco, Jordi; Artigas, David; Torner, Lluis

    2017-03-01

    Bound states in the continuum (BICs) are radiationless localized states embedded in the part of the parameter space that otherwise corresponds to radiative modes. Many decades after their original prediction and early observations in acoustic systems, such states have been demonstrated recently in photonic structures with engineered geometries. Here, we put forward a mechanism, based on waveguiding structures that contain anisotropic birefringent materials, that affords the existence of BICs with fundamentally new properties. In particular, anisotropy-induced BICs may exist in symmetric as well as in asymmetric geometries; they may form in tunable angular propagation directions; their polarization may be pure transverse electric, pure transverse magnetic or full vector with tunable polarization hybridity; and they may be the only possible bound states of properly designed structures, and thus appear as a discrete, isolated bound state embedded in a whole sea of radiative states.

  16. Wave propagation in nanostructures nonlocal continuum mechanics formulations

    CERN Document Server

    Gopalakrishnan, Srinivasan

    2013-01-01

    Wave Propagation in Nanostructures describes the fundamental and advanced concepts of waves propagating in structures that have dimensions of the order of nanometers. The book is fundamentally based on non-local elasticity theory, which includes scale effects in the continuum model. The book predominantly addresses wave behavior in carbon nanotubes and graphene structures, although the methods of analysis provided in this text are equally applicable to other nanostructures. The book takes the reader from the fundamentals of wave propagation in nanotubes to more advanced topics such as rotating nanotubes, coupled nanotubes, and nanotubes with magnetic field and surface effects. The first few chapters cover the basics of wave propagation, different modeling schemes for nanostructures and introduce non-local elasticity theories, which form the building blocks for understanding the material provided in later chapters. A number of interesting examples are provided to illustrate the important features of wave behav...

  17. On the Derivation of Boundary Conditions for Continuum Dislocation Dynamics

    Directory of Open Access Journals (Sweden)

    Thomas Hochrainer

    2017-07-01

    Full Text Available Continuum dislocation dynamics (CDD is a single crystal strain gradient plasticity theory based exclusively on the evolution of the dislocation state. Recently, we derived a constitutive theory for the average dislocation velocity in CDD in a phase field-type description for an infinite domain. In the current work, so-called rational thermodynamics is employed to obtain thermodynamically consistent boundary conditions for the dislocation density variables of CDD. We find that rational thermodynamics reproduces the bulk constitutive equations as obtained from irreversible thermodynamics. The boundary conditions we find display strong parallels to the microscopic traction conditions derived by Gurtin and Needleman (M.E. Gurtin and A. Needleman, J. Mech. Phys. Solids 53 (2005 1–31 for strain gradient theories based on the Kröner–Nye tensor.

  18. Search for a continuum limit of the PMS phase

    CERN Document Server

    Ayyar, Venkitesh

    2016-01-01

    Previous studies of a simple four-fermion model with staggered fermions in 3D have shown the existence of an exotic quantum critical point, where one may be able to define a continuum limit of the Paramagnetic Strong Phase (or the PMS phase). We believe the existence of the critical point suggests a new mechanism for generating fermion masses. In this work we begin the search for this quantum critical point in 4D by extending the 3D model to 4D. Unlike in 3D, now we do find evidence for an intermediate spontaneously broken phase (FM phase) and are able compute the phase boundaries accurately. In terms of the bare coupling, the width of the intermediate region appears to be quite small.

  19. A 45-MHz continuum survey of the northern hemisphere

    Science.gov (United States)

    Maeda, K.; Alvarez, H.; Aparici, J.; May, J.; Reich, P.

    We present a 45-MHz continuum survey in the declination range of +5 to +65 degrees in sets of maps in galactic and equatorial coordinates (epoch 1950). The observations were made at 46.5 MHz with a circular filled array of the Japanese Middle and Upper Atmosphere Radar (MU Radar) located at Shigaraki, Japan. The radar array consists of 475 crossed 3-element Yagis arranged within a circle of 103 m diameter, with a the half-power beam width of 3.6 degrees. In order to calibrate the data from the MU radar we used the Chilean 45-MHz survey which was made with an array of size comparable with that of the MU radar. The data processing was performed at the Maipu Radio Observatory, University of Chile, and this process brought the data to 45 MHz. The final maps were obtained at the Max-Plank-Institut fur Radioastronomie, Germany, using of the NOD2 program package.

  20. Scissors strength in the quasi-continuum of actinides

    Directory of Open Access Journals (Sweden)

    Guttormsen M.

    2014-03-01

    Full Text Available The M1-scissors resonance has been measured for the first time in the quasi-continuum of actinides. The strength and position of the resonances in 231,232,233Th were determined by particle-γ coincidences using deuteron induced reactions on a 232Th target. The residual nuclei show a strong integrated strength of BM1 = 9 − 11 µn2 in the Eγ = 1.0 − 3.5 MeV region. The presence of the scissors resonance modifies significantly the (n,γ cross section, which has impact on fuel-cycle simulations of fast nuclear reactors and nucleosynthesis in explosive stellar environments.

  1. Recent developments in evolutionary structural optimization (ESO) for continuum structures

    Science.gov (United States)

    Xie, Yi Min; Huang, Xiaodong

    2010-06-01

    Evolutionary Structural Optimization (ESO) and its later version bi-directional ESO (BESO) have gained widespread popularity among researchers in structural optimization and practitioners in engineering and architecture. However, there have also been many critical comments on various aspects of ESO/BESO. To address those criticisms, we have carried out extensive work to improve the original ESO/BESO algorithms in recent years. This paper summarizes some of the latest developments in the BESO method for topology optimization of continuum structures. Numerical results show that the ESO/BESO solutions agree well with those of other well-established topology optimization methods. It indicates that the current BESO method has great potential to become a robust and efficient design tool for practical applications in engineering and architecture.

  2. Harnessing the Interaction Continuum for Subtle Assisted Living

    Science.gov (United States)

    García-Herranz, Manuel; Olivera, Fernando; Haya, Pablo; Alamán, Xavier

    2012-01-01

    People interact with each other in many levels of attention, intention and meaning. This Interaction Continuum is used daily to deal with different contexts, adapting the interaction to communication needs and available resources. Nevertheless, computer-supported interaction has mainly focused on the most direct, explicit and intrusive types of human to human Interaction such as phone calls, emails, or video conferences. This paper presents the results of exploring and exploiting the potentials of undemanding interaction mechanisms, paying special attention to subtle communication and background interaction. As we argue the benefits of this type of interaction for people with special needs, we present a theoretical framework to define it and propose a proof of concept based on Augmented Objects and a color codification mechanism. Finally, we evaluate and analyze the strengths and limitations of such approach with people with cognitive disabilities. PMID:23012573

  3. Continuum analysis of biological systems conserved quantities, fluxes and forces

    CERN Document Server

    Suraishkumar, G K

    2014-01-01

    This book addresses the analysis, in the continuum regime, of biological systems at various scales, from the cellular level to the industrial one. It presents both fundamental conservation principles (mass, charge, momentum and energy) and relevant fluxes resulting from appropriate driving forces, which are important for the analysis, design and operation of biological systems. It includes the concept of charge conservation, an important principle for biological systems that is not explicitly covered in any other book of this kind. The book is organized in five parts: mass conservation; charge conservation; momentum conservation; energy conservation; and multiple conservations simultaneously applied. All mathematical aspects are presented step by step, allowing any reader with a basic mathematical background (calculus, differential equations, linear algebra, etc.) to follow the text with ease. The book promotes an intuitive understanding of all the relevant principles and in so doing facilitates their applica...

  4. mHealth Education Applications Along the Cancer Continuum.

    Science.gov (United States)

    Davis, Sharon Watkins; Oakley-Girvan, Ingrid

    2015-06-01

    The majority of adults worldwide own a mobile phone, including those in under-resourced communities. Mobile health (mhealth) education technologies present a promising mechanism for improving cancer prevention, treatment, and follow-up. The purpose of this study was to summarize the literature related to mobile phone (mhealth) applications for patient education specific to cancer and identify current recommendations from randomized studies. In particular, we were interested in identifying mobile phone applications along the cancer continuum, from cancer prevention to survivorship. The authors identified 28 articles reporting on mobile applications for patients related to cancer. Articles were identified in all categories along the cancer continuum, including health professional involvement in application development. Of these, six involved direct patient education, and eight focused on improving patient/professional communication and patient self-management. However, only six of the studies were randomized interventions. The potential for mobile applications to help overcome the "health care gap" has not yet been realized in the studies from the USA that were reviewed for this paper. However, early recommendations are emerging that support the use of mHealth communications to change behaviors for cancer prevention, early detection, and symptom management and improved patient-provider communication. Recommendations include short messages, use of multiple modalities as patient characteristics dictate comfort with mHealth communication, and the inclusion of patients and health professionals to develop and test applications. Tailoring mHealth to particular cultures, languages, and ethnic groups may also represent a unique possibility to provide accessible information and education at minimal cost for under-resourced communities and individuals.

  5. Varieties of Voice-Hearing: Psychics and the Psychosis Continuum

    Science.gov (United States)

    Powers, Albert R.; Kelley, Megan S.; Corlett, Philip R.

    2017-01-01

    Hearing voices that are not present is a prominent symptom of serious mental illness. However, these experiences may be common in the non-help-seeking population, leading some to propose the existence of a continuum of psychosis from health to disease. Thus far, research on this continuum has focused on what is impaired in help-seeking groups. Here we focus on protective factors in non-help-seeking voice-hearers. We introduce a new study population: clairaudient psychics who receive daily auditory messages. We conducted phenomenological interviews with these subjects, as well as with patients diagnosed with a psychotic disorder who hear voices, people with a diagnosis of a psychotic disorder who do not hear voices, and matched control subjects (without voices or a diagnosis). We found the hallucinatory experiences of psychic voice-hearers to be very similar to those of patients who were diagnosed. We employed techniques from forensic psychiatry to conclude that the psychics were not malingering. Critically, we found that this sample of non-help-seeking voice hearers were able to control the onset and offset of their voices, that they were less distressed by their voice-hearing experiences and that, the first time they admitted to voice-hearing, the reception by others was much more likely to be positive. Patients had much more negative voice-hearing experiences, were more likely to receive a negative reaction when sharing their voices with others for the first time, and this was subsequently more disruptive to their social relationships. We predict that this sub-population of healthy voice-hearers may have much to teach us about the neurobiology, cognitive psychology and ultimately the treatment of voices that are distressing. PMID:28053132

  6. Benchmarking Continuum Solvent Models for Keto-Enol Tautomerizations.

    Science.gov (United States)

    McCann, Billy W; McFarland, Stuart; Acevedo, Orlando

    2015-08-13

    Experimental free energies of tautomerization, ΔGT, were used to benchmark the gas-phase predictions of 17 different quantum mechanical methods and eight basis sets for seven keto-enol tautomer pairs dominated by their enolic form. The G4 method and M06/6-31+G(d,p) yielded the most accurate results, with mean absolute errors (MAE's) of 0.95 and 0.71 kcal/mol, respectively. Using these two theory levels, the solution-phase ΔGT values for 23 unique tautomer pairs composed of aliphatic ketones, β-dicarbonyls, and heterocycles were computed in multiple protic and aprotic solvents. The continuum solvation models, namely, polarizable continuum model (PCM), polarizable conductor calculation model (CPCM), and universal solvation model (SMD), gave relatively similar MAE's of ∼1.6-1.7 kcal/mol for G4 and ∼1.9-2.0 kcal/mol with M06/6-31+G(d,p). Partitioning the tautomer pairs into their respective molecular types, that is, aliphatic ketones, β-dicarbonyls, and heterocycles, and separating out the aqueous versus nonaqueous results finds G4/PCM utilizing the UA0 cavity to be the overall most accurate combination. Free energies of activation, ΔG(‡), for the base-catalyzed keto-enol interconversion of 2-nitrocyclohexanone were also computed using six bases and five solvents. The M06/6-31+G(d,p) reproduced the ΔG(‡) with MAE's of 1.5 and 1.8 kcal/mol using CPCM and SMD, respectively, for all combinations of base and solvent. That specific enolization was previously proposed to proceed via a concerted mechanism in less polar solvents but shift to a stepwise mechanism in more polar solvents. However, the current calculations suggest that the stepwise mechanism operates in all solvents.

  7. Examining the scale of the Behaviour Energy Efficiency Continuum

    Energy Technology Data Exchange (ETDEWEB)

    Laitner, John A. ' Skip' ; Ehrhardt-Martinez, Karen; McKinney, Vanessa (ACEEE, American Council for an Energy-Efficient Economy, Washington, D.C. (United States))

    2009-07-01

    There is a burgeoning interest in the 'human dimension' of energy use. As but one example, the second annual Behavior, Energy, and Climate Conference (co-convened by the American Council for an Energy-Efficient Economy, the Precourt Inst. for Energy Efficiency, and the California Inst. for Energy and Environment) exceeded capacity almost six weeks before the November 2008 conference date (see, for example, the conference website at http://www.BECCconference.org). At the same time, many analysts suggest that, yes, behaviour-oriented programs provide a nice way to help deploy smart technologies but that they are, essentially, boutique or niche strategies; they can only help round out a technology-based deployment effort. We suggest to the contrary; elements of the behaviour or human dimension may have a surprising scale which rivals a pure technology-based perspective in terms of expected efficiency gains. In this paper we highlight the potential impact of changed habits, lifestyles and technology-based behaviours in terms of potential energy savings within the United States for the residential sector. We explore the level of potential savings along what we call a Behaviour Energy Response Continuum. In other words, we explore the energy savings if different motivations and habits drove a different behaviour, and if different lifestyles similarly drove a different behaviour as they all, in turn, affect energy consumption. Preliminary research suggests that changed behaviours might reduce household use of energy by about 22 percent within the United States. In this paper we characterize the elements along this behaviour continuum, estimate the potential impact, and describe potential next steps in the needed research.

  8. Continuum kinetic and multi-fluid simulations of classical sheaths

    Science.gov (United States)

    Cagas, P.; Hakim, A.; Juno, J.; Srinivasan, B.

    2017-02-01

    The kinetic study of plasma sheaths is critical, among other things, to understand the deposition of heat on walls, the effect of sputtering, and contamination of the plasma with detrimental impurities. The plasma sheath also provides a boundary condition and can often have a significant global impact on the bulk plasma. In this paper, kinetic studies of classical sheaths are performed with the continuum kinetic code, Gkeyll, which directly solves the Vlasov-Maxwell equations. The code uses a novel version of the finite-element discontinuous Galerkin scheme that conserves energy in the continuous-time limit. The fields are computed using Maxwell equations. Ionization and scattering collisions are included; however, surface effects are neglected. The aim of this work is to introduce the continuum kinetic method and compare its results with those obtained from an already established finite-volume multi-fluid model also implemented in Gkeyll. Novel boundary conditions on the fluids allow the sheath to form without specifying wall fluxes, so the fluids and fields adjust self-consistently at the wall. The work presented here demonstrates that the kinetic and fluid results are in agreement for the momentum flux, showing that in certain regimes, a multi-fluid model can be a useful approximation for simulating the plasma boundary. There are differences in the electrostatic potential between the fluid and kinetic results. Further, the direct solutions of the distribution function presented here highlight the non-Maxwellian distribution of electrons in the sheath, emphasizing the need for a kinetic model. The densities, velocities, and the potential show a good agreement between the kinetic and fluid results. However, kinetic physics is highlighted through higher moments such as parallel and perpendicular temperatures which provide significant differences from the fluid results in which the temperature is assumed to be isotropic. Besides decompression cooling, the heat flux

  9. Radio Continuum Surveys with Square Kilometre Array Pathfinders

    Science.gov (United States)

    Norris, Ray P.; Afonso, J.; Bacon, D.; Beck, Rainer; Bell, Martin; Beswick, R. J.; Best, Philip; Bhatnagar, Sanjay; Bonafede, Annalisa; Brunetti, Gianfranco; Budavári, Tamás; Cassano, Rossella; Condon, J. J.; Cress, Catherine; Dabbech, Arwa; Feain, I.; Fender, Rob; Ferrari, Chiara; Gaensler, B. M.; Giovannini, G.; Haverkorn, Marijke; Heald, George; Van der Heyden, Kurt; Hopkins, A. M.; Jarvis, M.; Johnston-Hollitt, Melanie; Kothes, Roland; Van Langevelde, Huib; Lazio, Joseph; Mao, Minnie Y.; Martínez-Sansigre, Alejo; Mary, David; Mcalpine, Kim; Middelberg, E.; Murphy, Eric; Padovani, P.; Paragi, Zsolt; Prandoni, I.; Raccanelli, A.; Rigby, Emma; Roseboom, I. G.; Röttgering, H.; Sabater, Jose; Salvato, Mara; Scaife, Anna M. M.; Schilizzi, Richard; Seymour, N.; Smith, Dan J. B.; Umana, Grazia; Zhao, G.-B.; Zinn, Peter-Christian

    2013-03-01

    In the lead-up to the Square Kilometre Array (SKA) project, several next-generation radio telescopes and upgrades are already being built around the world. These include APERTIF (The Netherlands), ASKAP (Australia), e-MERLIN (UK), VLA (USA), e-EVN (based in Europe), LOFAR (The Netherlands), MeerKAT (South Africa), and the Murchison Widefield Array. Each of these new instruments has different strengths, and coordination of surveys between them can help maximise the science from each of them. A radio continuum survey is being planned on each of them with the primary science objective of understanding the formation and evolution of galaxies over cosmic time, and the cosmological parameters and large-scale structures which drive it. In pursuit of this objective, the different teams are developing a variety of new techniques, and refining existing ones. To achieve these exciting scientific goals, many technical challenges must be addressed by the survey instruments. Given the limited resources of the global radio-astronomical community, it is essential that we pool our skills and knowledge. We do not have sufficient resources to enjoy the luxury of re-inventing wheels. We face significant challenges in calibration, imaging, source extraction and measurement, classification and cross-identification, redshift determination, stacking, and data-intensive research. As these instruments extend the observational parameters, we will face further unexpected challenges in calibration, imaging, and interpretation. If we are to realise the full scientific potential of these expensive instruments, it is essential that we devote enough resources and careful study to understanding the instrumental effects and how they will affect the data. We have established an SKA Radio Continuum Survey working group, whose prime role is to maximise science from these instruments by ensuring we share resources and expertise across the projects. Here we describe these projects, their science goals

  10. Lasing action from photonic bound states in continuum

    Science.gov (United States)

    Kodigala, Ashok; Lepetit, Thomas; Gu, Qing; Bahari, Babak; Fainman, Yeshaiahu; Kanté, Boubacar

    2017-01-01

    In 1929, only three years after the advent of quantum mechanics, von Neumann and Wigner showed that Schrödinger’s equation can have bound states above the continuum threshold. These peculiar states, called bound states in the continuum (BICs), manifest themselves as resonances that do not decay. For several decades afterwards the idea lay dormant, regarded primarily as a mathematical curiosity. In 1977, Herrick and Stillinger revived interest in BICs when they suggested that BICs could be observed in semiconductor superlattices. BICs arise naturally from Feshbach’s quantum mechanical theory of resonances, as explained by Friedrich and Wintgen, and are thus more physical than initially realized. Recently, it was realized that BICs are intrinsically a wave phenomenon and are thus not restricted to the realm of quantum mechanics. They have since been shown to occur in many different fields of wave physics including acoustics, microwaves and nanophotonics. However, experimental observations of BICs have been limited to passive systems and the realization of BIC lasers has remained elusive. Here we report, at room temperature, lasing action from an optically pumped BIC cavity. Our results show that the lasing wavelength of the fabricated BIC cavities, each made of an array of cylindrical nanoresonators suspended in air, scales with the radii of the nanoresonators according to the theoretical prediction for the BIC mode. Moreover, lasing action from the designed BIC cavity persists even after scaling down the array to as few as 8-by-8 nanoresonators. BIC lasers open up new avenues in the study of light-matter interaction because they are intrinsically connected to topological charges and represent natural vector beam sources (that is, there are several possible beam shapes), which are highly sought after in the fields of optical trapping, biological sensing and quantum information.

  11. Pennsylvania's Forests, 2009

    Science.gov (United States)

    George L. McCaskill; William H. McWilliams; Carol A. Alerich; Brett J. Butler; Susan J. Crocker; Grant M. Domke; Doug Griffith; Cassandra M. Kurtz; Shawn Lehman; Tonya W. Lister; Randall S. Morin; W. Keith Moser; Paul Roth; Rachel Riemann; James A. Westfall

    2013-01-01

    The second full annual inventory of Pennsylvania's forests reports a stable base of 16.7 million acres of forest land. Northern hardwoods and mixed-oak forest-type groups account for 54 and 32 percent of the forest land, respectively. The State's forest land averages about 61 dry tons of wood per acre and almost 6,500 board feet (International ¼-inch...

  12. A Mathematical Analysis of Atomistic-to-Continuum (AtC) Multiscale Coupling Methods

    Energy Technology Data Exchange (ETDEWEB)

    Gunzburger, Max

    2013-11-13

    We have worked on several projects aimed at improving the efficiency and understanding of multiscale methods, especially those applicable to problems involving atomistic-to-continuum coupling. Activities include blending methods for AtC coupling and efficient quasi-continuum methods for problems with long-range interactions.

  13. Three-dimensional Hybrid Continuum-Atomistic Simulations for Multiscale Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Wijesinghe, S; Hornung, R; Garcia, A; Hadjiconstantinou, N

    2004-04-15

    We present an adaptive mesh and algorithmic refinement (AMAR) scheme for modeling multi-scale hydrodynamics. The AMAR approach extends standard conservative adaptive mesh refinement (AMR) algorithms by providing a robust flux-based method for coupling an atomistic fluid representation to a continuum model. The atomistic model is applied locally in regions where the continuum description is invalid or inaccurate, such as near strong flow gradients and at fluid interfaces, or when the continuum grid is refined to the molecular scale. The need for such ''hybrid'' methods arises from the fact that hydrodynamics modeled by continuum representations are often under-resolved or inaccurate while solutions generated using molecular resolution globally are not feasible. In the implementation described herein, Direct Simulation Monte Carlo (DSMC) provides an atomistic description of the flow and the compressible two-fluid Euler equations serve as our continuum-scale model. The AMR methodology provides local grid refinement while the algorithm refinement feature allows the transition to DSMC where needed. The continuum and atomistic representations are coupled by matching fluxes at the continuum-atomistic interfaces and by proper averaging and interpolation of data between scales. Our AMAR application code is implemented in C++ and is built upon the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) framework developed at Lawrence Livermore National Laboratory. SAMRAI provides the parallel adaptive gridding algorithm and enables the coupling between the continuum and atomistic methods.

  14. EFL Learners' Awareness of Metonymy-Metaphor Continuum in Figurative Expressions

    Science.gov (United States)

    Chen, Yi-chen; Lai, Huei-ling

    2012-01-01

    Most studies about figurative language learning focus on metaphor rather than metonymy; however, the interactions of metonymy and metaphor are so intricate that the boundary forms not a dichotomy but a continuum. Such a continuum and its influences on figurative language learning have not been studied in depth. The present study investigates EFL…

  15. Possibilities of modeling masonry as a composite softening material: Interface modeling and anisotropic continuum modeling

    NARCIS (Netherlands)

    Lourenço, P.B.; Rots, J.G.

    1998-01-01

    Results of using recently developed material models for the analysis of masonry structures are shown. Both interface modeling, in which masonry components (units and joints) are represented, as continuum modeling, in which masonry is represented as a homogeneous continuum, are addressed. It is shown

  16. A continuum model for flow induced by metachronal coordination between beating cilia

    NARCIS (Netherlands)

    Hussong, J.; Breugem, W.P.; Westerweel, J.

    2011-01-01

    In this numerical study we investigate the flow induced by metachronal coordination between beating cilia arranged in a densely packed layer by means of a continuum model. The continuum approach allows us to treat the problem as two-dimensional as well as stationary, in a reference frame moving with

  17. Nursing Leadership and Care Coordination: Creating Excellence in Coordinating Care Across the Continuum.

    Science.gov (United States)

    Bower, Kathleen A

    2016-01-01

    Continuum Care is different today from in the past. It requires care coordination with an emphasis on relationships and new roles. Nurses and nurse leaders must be located at the epicenter of developing strategies to align resources with patients and family along all points of the continuum.

  18. Combined discrete particle and continuum model predicting solid-state fermentation in a drum fermentor

    NARCIS (Netherlands)

    Schutyser, M.A.I.; Schutyser, M.A.I.; Briels, Willem J.; Boom, R.M.; Boom, R.M.; Rinzema, A.

    2004-01-01

    The development of mathematical models facilitates industrial (large-scale) application of solid-state fermentation (SSF). In this study, a two-phase model of a drum fermentor is developed that consists of a discrete particle model (solid phase) and a continuum model (gas phase). The continuum model

  19. Evidence against the continuum structure underlying motivation measures derived from self-determination theory.

    Science.gov (United States)

    Chemolli, Emanuela; Gagné, Marylène

    2014-06-01

    Self-determination theory (SDT) proposes a multidimensional conceptualization of motivation in which the different regulations are said to fall along a continuum of self-determination. The continuum has been used as a basis for using a relative autonomy index as a means to create motivational scores. Rasch analysis was used to verify the continuum structure of the Multidimensional Work Motivation Scale and of the Academic Motivation Scale. We discuss the concept of continuum against SDT's conceptualization of motivation and argue against the use of the relative autonomy index on the grounds that evidence for a continuum structure underlying the regulations is weak and because the index is statistically problematic. We suggest exploiting the full richness of SDT's multidimensional conceptualization of motivation through the use of alternative scoring methods when investigating motivational dynamics across life domains.

  20. A constitutive model of soft tissue: From nanoscale collagen to tissue continuum

    KAUST Repository

    Tang, Huang

    2009-04-08

    Soft collagenous tissue features many hierarchies of structure, starting from tropocollagen molecules that form fibrils, and proceeding to a bundle of fibrils that form fibers. Here we report the development of an atomistically informed continuum model of collagenous tissue. Results from full atomistic and molecular modeling are linked with a continuum theory of a fiber-reinforced composite, handshaking the fibril scale to the fiber and continuum scale in a hierarchical multi-scale simulation approach. Our model enables us to study the continuum-level response of the tissue as a function of cross-link density, making a link between nanoscale collagen features and material properties at larger tissue scales. The results illustrate a strong dependence of the continuum response as a function of nanoscopic structural features, providing evidence for the notion that the molecular basis for protein materials is important in defining their larger-scale mechanical properties. © 2009 Biomedical Engineering Society.

  1. Solitary waves in a two-dimensional nonlinear Dirac equation: from discrete to continuum

    Science.gov (United States)

    Cuevas-Maraver, J.; Kevrekidis, P. G.; Aceves, A. B.; Saxena, Avadh

    2017-12-01

    In the present work, we explore a nonlinear Dirac equation motivated as the continuum limit of a binary waveguide array model. We approach the problem both from a near-continuum perspective as well as from a highly discrete one. Starting from the former, we see that the continuum Dirac solitons can be continued for all values of the discretization (coupling) parameter, down to the uncoupled (so-called anti-continuum) limit where they result in a 9-site configuration. We also consider configurations with 1- or 2-sites at the anti-continuum limit and continue them to large couplings, finding that they also persist. For all the obtained solutions, we examine not only the existence, but also the spectral stability through a linearization analysis and finally consider prototypical examples of the dynamics for a selected number of cases for which the solutions are found to be unstable.

  2. PREFACE: Continuum Models and Discrete Systems Symposia (CMDS-12)

    Science.gov (United States)

    Chakrabarti, Bikas K.

    2011-09-01

    The 12th International Symposium on Continuum Models and Discrete Systems (CMDS-12) (http://www.saha.ac.in/cmp/cmds.12/) took place at the Saha Institute of Nuclear Physics in Kolkata from 21-25 February 2011. Previous CMDS symposia were held in Kielce (Poland, 1975), Mont Gabriel (Canada, 1977), Freudenstadt (Federal Republic of Germany, 1979), Stockholm (Sweden, 1981), Nottingham (United Kingdom, 1985), Dijon (France, 1989), Paderborn (Germany, 1992), Varna (Bulgaria, 1995), Istanbul (Turkey, 1998), Shoresh (Israel, 2003) and Paris (France, 2007). The broad interdisciplinary character, limited number of participants (not exceeding 100) and informal and friendly atmosphere of these meetings has made them a well-acknowledged place to make highly fruitful contacts and exchange ideas, methods and results. The purpose of CMDS is to bring together scientists with different backgrounds who work on continuum theories of discrete mechanical and thermodynamical systems in the fields of mathematics, theoretical and applied mechanics, physics, material science, and engineering. The spirit of the CMDS meetings is to stimulate extensive and active interdisciplinary research. The International Scientific Committee members of this conference were: David J Bergman (Chairman CMDS 10), Tel Aviv University, Israel; Bikas K Chakrabarti (Chairman CMDS 12), Saha Institute of Nuclear Physics, India; Alex Hansen, Norwegian University of Science and Technology, Norway; Hans Jürgen Herrmann, Institute for Building Materials, ETH, Switzerland; Esin Inan (Chairman CMDS 9), Istanbul Technical University, Turkey; Dominique Jeulin (Chairman CMDS 11), Ecole des Mines de Paris, France; Frank Juelicher, Max-Planck-Institute for the Physics of Complex Systems, Germany; Hikaru Kawamura, University of Osaka, Japan; Graeme Milton, University of Utah, USA; Natalia Movchan, University of Liverpool, UK; and Ping Sheng, The Hong Kong University of Science and Technology, Hong Kong. At CMDS-12 the topics

  3. FOREST CADASTRE COMISSIONS

    Directory of Open Access Journals (Sweden)

    Cemal Bıyık

    2000-04-01

    Full Text Available In Turkey, forest areas are decreasing every day. On the other hand, being a wood product and the source of countless usage areas, the value of forest increases more and more. Delineation of forest areas, known as forest cadastre, are completed in developed countries. In general, with fprest cadastre the geometrical and legal status of forests are determined and registered in Land Title. Forest cadastre are carried out by Forest Cadastre Comissions according to the Forest Low 6831. Until today, only 60% of forest cadastre have been completed in 58 years from the start of forest cadastre work. The organization of Forest Cadastre Comissions have undergone various changes. Forest Cadastre Comissions have long suffered from many organizational and practical problems. In this study, current problems of Forest Cadastre Comissions are identified and examined. In result,, insufficient number of comissions, lack of theoretical and practical background and low motivation ot working personnal, and political and public pressure on the works of Forest Cadastre Comissions were identified as the main problems.

  4. Archives: Southern Forests: a Journal of Forest Science

    African Journals Online (AJOL)

    Items 1 - 50 of 57 ... Archives: Southern Forests: a Journal of Forest Science. Journal Home > Archives: Southern Forests: a Journal of Forest Science. Log in or Register to get access to full text downloads.

  5. Southern Forests: a Journal of Forest Science: Editorial Policies

    African Journals Online (AJOL)

    Southern Forests: a Journal of Forest Science: Editorial Policies. Journal Home > About the Journal > Southern Forests: a Journal of Forest Science: Editorial Policies. Log in or Register to get access to full text downloads.

  6. Southern Forests: a Journal of Forest Science: About this journal

    African Journals Online (AJOL)

    Southern Forests: a Journal of Forest Science: About this journal. Journal Home > Southern Forests: a Journal of Forest Science: About this journal. Log in or Register to get access to full text downloads.

  7. Continuum Source Atomic Absorption Spectrometry with a Photodiode Array Detector

    Science.gov (United States)

    Fernando, Reshan Armedious

    The designed continuum source atomic absorption spectrometer consists of a 300W xenon arc lamp (ILC Technology), a flame (Perkin-Elmer) or graphite furnace (Perkin-Elmer, Model HGA 2200) atomizer, a 1.33M focal length high resolution monochromator with 3600 gr/mm grating (McPherson, Model 209), and a 2048-element self scanning linear photodiode array detector (Princeton Instruments, Model PDA-2048). Detector operation, data acquisition and processing was done by using a 66MHz 486 DX/2 personal computer (Gateway 2000). In stage one, the system was optimized for flame atomization. The optimum lamp current, entrance slit width and height were found to be 10A, 20 mum, and 4 mm respectively. The resulted spectral band-pass of the monochromator/PDA combination is on the order of the average atomic absorption profile half-width (0.003 -0.004 nm). The flame parameters such as observation height, air/fuel ratio, and solution uptake rate were optimized along with the detector parameters such as exposure and accumulation for the lowest possible detection limit. The system has clearly demonstrated its multi-element detection capabilities. The calculated detection limits for the present system with an air-acetylene flame is approximately one order of magnitude lower than previously reported CSAAS detection limits, and are on the same order of magnitude as those commonly observed with single element hollow cathode lamp systems. In stage two, flame atomizer was replaced by a graphite furnace atomizer. When compared to the static signal given out by flame atomizer, the graphite furnace produces transient signals. Fast response time of the PDA is well within the time scale of the transient signals produce in graphite furnace and the multi-wavelength detection allows the background correction to be performed by visual inspection. The detection limits calculated for the present system are significantly lower than those previously reported for multi-element CSAAS systems, and are on

  8. Forest resources of Mississippi’s national forests, 2006

    Science.gov (United States)

    Sonja N. Oswalt

    2011-01-01

    This bulletin describes forest resource characteristics of Mississippi’s national forests, with emphasis on DeSoto National Forest, following the 2006 survey completed by the U.S. Department of Agriculture Forest Service, Forest Inventory and Analysis program. Mississippi’s national forests comprise > 1 million acres of forest land, or about 7 percent of all forest...

  9. Impact of decentralised forest management on forest cover changes ...

    African Journals Online (AJOL)

    Forest inventory techniques were used to estimate tree harvests as major drivers of forest cover changes. The area under closed forest cover decreased substantially ranging from 0.4%.y-1 to 1.3%.y-1 in the montane forests with higher forest loss recorded under exclusive state management. In the semi-arid, the forest under ...

  10. STATCONT: A statistical continuum level determination method for line-rich sources

    Science.gov (United States)

    Sánchez-Monge, Á.; Schilke, P.; Ginsburg, A.; Cesaroni, R.; Schmiedeke, A.

    2018-01-01

    STATCONT is a python-based tool designed to determine the continuum emission level in spectral data, in particular for sources with a line-rich spectrum. The tool inspects the intensity distribution of a given spectrum and automatically determines the continuum level by using different statistical approaches. The different methods included in STATCONT are tested against synthetic data. We conclude that the sigma-clipping algorithm provides the most accurate continuum level determination, together with information on the uncertainty in its determination. This uncertainty can be used to correct the final continuum emission level, resulting in the here called `corrected sigma-clipping method' or c-SCM. The c-SCM has been tested against more than 750 different synthetic spectra reproducing typical conditions found towards astronomical sources. The continuum level is determined with a discrepancy of less than 1% in 50% of the cases, and less than 5% in 90% of the cases, provided at least 10% of the channels are line free. The main products of STATCONT are the continuum emission level, together with a conservative value of its uncertainty, and datacubes containing only spectral line emission, i.e., continuum-subtracted datacubes. STATCONT also includes the option to estimate the spectral index, when different files covering different frequency ranges are provided.

  11. Gamow-Teller strength in the continuum and quenching problem

    CERN Document Server

    Sakai, H; Okamura, H; Nonaka, T; Ohnishi, T; Yako, K; Sekiguchi, K; Fujita, S; Satou, Y; Otsu, H; Uesaka, T; Ishida, S; Sakamoto, N; Greenfield, M B; Hatanaka, K

    1999-01-01

    Differential cross sections at theta sub l sub a sub b = 0.0 deg. - 12.3 deg. and a complete set of polarization transfer observables at theta sub l sub a sub b = 0.0 deg. are measured for the sup 9 sup 0 Zr(p, n) reaction at T sub p = 295 MeV. A multipole decomposition (MD) technique is applied to the cross sections to extract partial cross sections sigma sub L with L = 0, 1, 2, and 3 contributions. A significant amount of sigma sub L sub = sub 0 is found in the highly excited continuum region. After subtracting the estimated iso-vector spin-monopole strength from sigma sub L sub = sub 0 , the Gamow-Teller (GT) strength B(GT) is deduced to be S subbeta sub - = SIGMA B(GT) = 28 +- 1.6 +- 5.4. The total spin transfer SIGMA(0 deg. ) which is independent of the nuclear reaction mechanisms such as the effective nucleon-nucleon interaction or distortions is derived from the complete set of polarization transfer observables. It is close to unity up to 50 MeV excitation indicating the strong spin-flip character of t...

  12. Continuum damage modeling in ductile materials using level sets

    Science.gov (United States)

    de Brauer, Alexia; Udaykumar, H. S.

    2017-06-01

    Ductile materials under high-velocity impact undergo large deformation and eventually damage. Damage alters the mechanical behavior of the materials and can lead to fracture and fragmentation. This work proposes a general Eulerian framework to model fracture and interfacial debonding in ductile materials. The current effort focuses on a plate impact problem, where a crack forms due to damage accumulation causing a discontinuity in the material. Damage accumulation is described by the continuum damage models. The level set approach is adopted for both tracking the sharp material interfaces and creating the crack. Results are found to be in good agreement with experimental data and two other commercial codes, CTH and EPIC. Also, damage is considered at the interfaces between two bonded materials, such as particles embedded in a matrix in a composite material. The progressive decohesion of the interfaces due to dynamic loading is simulated via a cohesive zone model. The result shows the ability of the code to handle the separation of the interfaces and create voids. This work has been funded from the AFRL-RW, Computational Mechanics Branch, Eglin AFB, Program Manager: Dr. Angela Diggs.

  13. Continuum damage modeling through theoretical and experimental pressure limit formulas

    Directory of Open Access Journals (Sweden)

    Fatima Majid

    2018-01-01

    Full Text Available In this paper, we developed a mathematical modeling to represent the damage of thermoplastic pipes. On the one hand, we adapted the theories of the rupture pressure to fit the High Density Polyethylene (HDPE case. Indeed, the theories for calculating the rupture pressure are multiple, designed originally for steels and alloys. For polymer materials, we have found that these theories can be adapted using a coefficient related to the nature of the studied material. The HDPE is characterized by two important values of pressure, deduced from the ductile form of the internal pressures evolution until burst. For this reason, we have designed an alpha coefficient taking into account these two pressures and giving a good approximation of the evolution of the experimental burst pressures through the theoretically corrected ones, using Faupel㒒s pressure formula. Then, we can deduce the evolution of the theoretical damage using the calculated pressures. On the other hand, two other mathematical models were undertaken. The first one has given rise to an adaptive model referring to an expression of the pressure as a function of the life fraction, the characteristic pressures and the critical life fraction. The second model represents a continuum damage model incorporating the pressure equations as a function of the life fraction and based on the burst pressure�s static damage model. These models represent important tools for industrials to assess the failure of thermoplastic pipes and proceed quick checks

  14. Brain-computer interfaces in the continuum of consciousness.

    Science.gov (United States)

    Kübler, Andrea; Kotchoubey, Boris

    2007-12-01

    To summarize recent developments and look at important future aspects of brain-computer interfaces. Recent brain-computer interface studies are largely targeted at helping severely or even completely paralysed patients. The former are only able to communicate yes or no via a single muscle twitch, and the latter are totally nonresponsive. Such patients can control brain-computer interfaces and use them to select letters, words or items on a computer screen, for neuroprosthesis control or for surfing the Internet. This condition of motor paralysis, in which cognition and consciousness appear to be unaffected, is traditionally opposed to nonresponsiveness due to disorders of consciousness. Although these groups of patients may appear to be very alike, numerous transition states between them are demonstrated by recent studies. All nonresponsive patients can be regarded on a continuum of consciousness which may vary even within short time periods. As overt behaviour is lacking, cognitive functions in such patients can only be investigated using neurophysiological methods. We suggest that brain-computer interfaces may provide a new tool to investigate cognition in disorders of consciousness, and propose a hierarchical procedure entailing passive stimulation, active instructions, volitional paradigms, and brain-computer interface operation.

  15. Application of differential sensitivity theory to continuum mechanics

    Science.gov (United States)

    Maudlin, P. J.; Henninger, R. J.; Harstad, E. N.

    A sensitivity technique used successfully in the early eighties, called Differential Sensitivity Theory (DST), is applied to a system of time-dependent continuum mechanics equations. DST uses adjoint techniques to determine exact sensitivity derivatives, i.e., if R is a calculational result of interest (response R) and alpha is a calculational input (parameter alpha(sub i) where the subscript is usually not indicated for convenience), then (partial derivative)R/(partial derivative)(alpha)(sub i) is defined as the sensitivity. The advantage of using DST over other sensitivity analysis techniques is mainly economic: for an n-parameter problem all n sensitivities can be obtained by integrating the solutions from only two calculations, a so-called forward (physical) calculation and its corresponding adjoint calculation. This work describes the derivation and solution of the appropriate set of adjoint and sensitivity equations for the ultimate purpose of computing sensitivities for high-rate two dimensional, multi-component, high deformation problems.

  16. Numerical Calculations Of Quantum Field Theories On The Continuum

    CERN Document Server

    Emirdag, P

    2002-01-01

    Source Galerkin technique is an alternative numerical method developed by Garcìa, Guralnik, and Lawson at Brown. It is not based on any statistical methods and has controllable errors. It also has the advantage that it can be used in a continuum formulation. This new method promises an increase in accuracy and speed of calculations. In this method, we treat field theory with the presence of external sources. The functional relations become a set of coupled differential equations for the generating functional Z. Source Galerkin is used to solve these equations for the Green's functions of the theory. According to this technique, the set of the residuals and the test functions are required to be orthogonal with respect to some inner product. The test functions that we are using are polynomials that consists of source terms and preserve the group symmetry of the problem. Symmetries of translation and reflection invariance are used in constructing the solution. A good choice of the test functions and t...

  17. ON CONTINUUM-DRIVEN WINDS FROM ROTATING STARS

    Energy Technology Data Exchange (ETDEWEB)

    Shacham, Tomer; Shaviv, Nir J. [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2012-10-01

    We study the dynamics of continuum-driven winds from rotating stars and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are sufficiently concentrated toward the poles to spin-up the star. A twin-lobe structure of the ejected nebula is seen to be a generic consequence of critical rotation. We find that if the pressure in such stars is sufficiently dominated by radiation, an equatorial ejection of mass will occur during eruptions. These results are then applied to {eta}-Carinae. We show that if it began its life with a high enough angular momentum, the present-day wind could have driven the star toward critical rotation, if it is the dominant mode of mass loss. We find that the shape and size of the Homunculus nebula, as given by our model, agree with recent observations. Moreover, the contraction expected due to the sudden increase in luminosity at the onset of the Great Eruption explains the equatorial 'skirt' as well.

  18. On Continuum-driven Winds from Rotating Stars

    Science.gov (United States)

    Shacham, Tomer; Shaviv, Nir J.

    2012-10-01

    We study the dynamics of continuum-driven winds from rotating stars and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are sufficiently concentrated toward the poles to spin-up the star. A twin-lobe structure of the ejected nebula is seen to be a generic consequence of critical rotation. We find that if the pressure in such stars is sufficiently dominated by radiation, an equatorial ejection of mass will occur during eruptions. These results are then applied to η-Carinae. We show that if it began its life with a high enough angular momentum, the present-day wind could have driven the star toward critical rotation, if it is the dominant mode of mass loss. We find that the shape and size of the Homunculus nebula, as given by our model, agree with recent observations. Moreover, the contraction expected due to the sudden increase in luminosity at the onset of the Great Eruption explains the equatorial "skirt" as well.

  19. Tracking Carbon along the Urban Watershed Continuum to Coastal Zones

    Science.gov (United States)

    Kaushal, S.

    2015-12-01

    Watersheds experiencing urbanization are constantly evolving in their structure and function, and their carbon cycle subsequently evolves across both space and time. We investigate how urbanization influences spatial and temporal evolution of the carbon cycle from small streams to major rivers in the Chesapeake Bay watershed using a variety of approaches such as stable isotopes, in situ water quality sensors, and remote sensing. Along the urban watershed continuum, we show that there is spatial evolution in: (1) the amount, chemical form, and reactivity of carbon, and (2) ecosystem metabolism and transformation of carbon sources from headwaters to coastal waters. Over shorter time scales, the interaction between land use and climate variability alters magnitude and sources of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) as revealed by stable isotopes and in situ sensors. Over longer time scales, land use change has altered particulate carbon transport in coastal waters and the evolution of river sediment plumes as suggested by remote sensing data. Furthermore, there are increased long-term bicarbonate alkalinity concentrations in streams and rivers, and we present new analytical approaches for studying river alkalinization due to human inputs and accelerated chemical weathering. In summary, urbanization alters carbon over space and time with major implications for downstream ecosystem metabolism, biological oxygen demand, carbon dioxide production, and river alkalinization.

  20. Organic carbon cycling in landfills: Model for a continuum approach

    Energy Technology Data Exchange (ETDEWEB)

    Bogner, J. [Argonne National Lab., IL (United States). Environmental Research Div.; Lagerkvist, A. [Luleaa Univ. of Technology (Sweden). Landfill Group

    1997-09-01

    Organic carbon cycling in landfills can be addressed through a continuum model where the end-points are conventional anaerobic digestion of organic waste (short-term analogue) and geologic burial of organic material (long-term analogue). Major variables influencing status include moisture state, temperature, organic carbon loading, nutrient status, and isolation from the surrounding environment. Bioreactor landfills which are engineered for rapid decomposition approach (but cannot fully attain) the anaerobic digester end-point and incur higher unit costs because of their high degree of environmental isolation and control. At the other extreme, uncontrolled land disposal of organic waste materials is similar to geologic burial where organic carbon may be aerobically recycled to atmospheric CO{sub 2}, anaerobically converted to CH{sub 4} and CO{sub 2} during early diagenesis, or maintained as intermediate or recalcitrant forms into geologic time (> 1,000 years) for transformations via kerogen pathways. A family of improved landfill models are needed at several scales (molecular to landscape) which realistically address landfill processes and can be validated with field data.

  1. A framework of teaching competencies across the medical education continuum.

    Science.gov (United States)

    Molenaar, W M; Zanting, A; van Beukelen, P; de Grave, W; Baane, J A; Bustraan, J A; Engbers, R; Fick, Th E; Jacobs, J C G; Vervoorn, J M

    2009-05-01

    The quality of teachers in higher education is subject of increasing attention, as exemplified by the development and implementation of guidelines for teacher qualifications at Universities in The Netherlands. Because medical education takes a special position in higher education the Council of Deans of Medical Schools in The Netherlands installed a national task force to explore a method to weigh criteria for teacher qualifications of medical teachers. A framework was developed covering competencies of teachers throughout the medical education continuum and including medicine, dentistry and veterinary medicine. The framework distinguishes 3 dimensions: (a) six domains of teaching (development - organization - execution - coaching - assessment - evaluation); (b) three levels in the organization at which teachers perform (micro, meso and macro level) and (c) competencies as integration of knowledge, skills and attitude and described as behaviour in specific context. The current framework is the result of several cycles of descriptions, feedback from the field and adaptations. It is meant as a guideline, leaving room for local detailing. The framework provides a common language that may be used not only by teachers and teacher trainers, but also by quality assurance committees, human resource managers and institutional boards.

  2. A continuum damage relation for hydrogen attack cavitation

    Energy Technology Data Exchange (ETDEWEB)

    Burg, M.W.D. van der; Giessen, E. van der [Delft Univ. of Technology (Netherlands). Lab. for Engineering Mechanics

    1997-07-01

    A continuum damage relation (CDR) is proposed to describe the failure process of hydrogen attack, i.e., grain boundary cavitation of steels under conditions of high temperature and high hydrogen pressure. The cavitation is caused by the chemical reaction of hydrogen with grain boundary carbides forming cavities filled with high pressure methane. The micromechanisms described are the grain boundary cavitation and the dislocation creep of the grains. The CDR is based on two extreme cavitation rate distribution modes. In the first mode, the cavitation rate along the facets is uniform, resulting in a hydrostatic dilatation while the creep deformations remain relatively small. In the second mode, cavitation proceeds predominantly on grain boundary facets transverse to the principal macroscopic stress. This part of the CDR builds on Tvergaard`s constitutive relation for intergranular creep rupture [Tvergaard, V., Acta Metallurgica, 1984, 32, 1977] where the facet cavitation is constrained by creep of the surrounding grains. The mode corresponding to the highest cavitation rate is the active mode. The two-dimensional version of the CDR is verified against detailed finite element analyses of hydrogen attack in planar polycrystalline aggregates. Finally, the generalization to a three-dimensional CDR is discussed.

  3. Verification of continuum drift kinetic equation solvers in NIMROD

    Energy Technology Data Exchange (ETDEWEB)

    Held, E. D.; Ji, J.-Y. [Utah State University, Logan, Utah 84322-4415 (United States); Kruger, S. E. [Tech-X Corporation, Boulder, Colorado 80303 (United States); Belli, E. A. [General Atomics, San Diego, California 92186-5608 (United States); Lyons, B. C. [Program in Plasma Physics, Princeton University, Princeton, New Jersey 08543-0451 (United States)

    2015-03-15

    Verification of continuum solutions to the electron and ion drift kinetic equations (DKEs) in NIMROD [C. R. Sovinec et al., J. Comp. Phys. 195, 355 (2004)] is demonstrated through comparison with several neoclassical transport codes, most notably NEO [E. A. Belli and J. Candy, Plasma Phys. Controlled Fusion 54, 015015 (2012)]. The DKE solutions use NIMROD's spatial representation, 2D finite-elements in the poloidal plane and a 1D Fourier expansion in toroidal angle. For 2D velocity space, a novel 1D expansion in finite elements is applied for the pitch angle dependence and a collocation grid is used for the normalized speed coordinate. The full, linearized Coulomb collision operator is kept and shown to be important for obtaining quantitative results. Bootstrap currents, parallel ion flows, and radial particle and heat fluxes show quantitative agreement between NIMROD and NEO for a variety of tokamak equilibria. In addition, velocity space distribution function contours for ions and electrons show nearly identical detailed structure and agree quantitatively. A Θ-centered, implicit time discretization and a block-preconditioned, iterative linear algebra solver provide efficient electron and ion DKE solutions that ultimately will be used to obtain closures for NIMROD's evolving fluid model.

  4. Continuum model for chiral induced spin selectivity in helical molecules

    Energy Technology Data Exchange (ETDEWEB)

    Medina, Ernesto [Centro de Física, Instituto Venezolano de Investigaciones Científicas, 21827, Caracas 1020 A (Venezuela, Bolivarian Republic of); Groupe de Physique Statistique, Institut Jean Lamour, Université de Lorraine, 54506 Vandoeuvre-les-Nancy Cedex (France); Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); González-Arraga, Luis A. [IMDEA Nanoscience, Cantoblanco, 28049 Madrid (Spain); Finkelstein-Shapiro, Daniel; Mujica, Vladimiro [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); Berche, Bertrand [Centro de Física, Instituto Venezolano de Investigaciones Científicas, 21827, Caracas 1020 A (Venezuela, Bolivarian Republic of); Groupe de Physique Statistique, Institut Jean Lamour, Université de Lorraine, 54506 Vandoeuvre-les-Nancy Cedex (France)

    2015-05-21

    A minimal model is exactly solved for electron spin transport on a helix. Electron transport is assumed to be supported by well oriented p{sub z} type orbitals on base molecules forming a staircase of definite chirality. In a tight binding interpretation, the spin-orbit coupling (SOC) opens up an effective π{sub z} − π{sub z} coupling via interbase p{sub x,y} − p{sub z} hopping, introducing spin coupled transport. The resulting continuum model spectrum shows two Kramers doublet transport channels with a gap proportional to the SOC. Each doubly degenerate channel satisfies time reversal symmetry; nevertheless, a bias chooses a transport direction and thus selects for spin orientation. The model predicts (i) which spin orientation is selected depending on chirality and bias, (ii) changes in spin preference as a function of input Fermi level and (iii) back-scattering suppression protected by the SO gap. We compute the spin current with a definite helicity and find it to be proportional to the torsion of the chiral structure and the non-adiabatic Aharonov-Anandan phase. To describe room temperature transport, we assume that the total transmission is the result of a product of coherent steps.

  5. Aggregation patterns from nonlocal interactions: Discrete stochastic and continuum modeling

    KAUST Repository

    Hackett-Jones, Emily J.

    2012-04-17

    Conservation equations governed by a nonlocal interaction potential generate aggregates from an initial uniform distribution of particles. We address the evolution and formation of these aggregating steady states when the interaction potential has both attractive and repulsive singularities. Currently, no existence theory for such potentials is available. We develop and compare two complementary solution methods, a continuous pseudoinverse method and a discrete stochastic lattice approach, and formally show a connection between the two. Interesting aggregation patterns involving multiple peaks for a simple doubly singular attractive-repulsive potential are determined. For a swarming Morse potential, characteristic slow-fast dynamics in the scaled inverse energy is observed in the evolution to steady state in both the continuous and discrete approaches. The discrete approach is found to be remarkably robust to modifications in movement rules, related to the potential function. The comparable evolution dynamics and steady states of the discrete model with the continuum model suggest that the discrete stochastic approach is a promising way of probing aggregation patterns arising from two- and three-dimensional nonlocal interaction conservation equations. © 2012 American Physical Society.

  6. Neoclassical Simulation of Tokamak Plasmas using Continuum Gyrokinetc Code TEMPEST

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X Q

    2007-11-09

    We present gyrokinetic neoclassical simulations of tokamak plasmas with self-consistent electric field for the first time using a fully nonlinear (full-f) continuum code TEMPEST in a circular geometry. A set of gyrokinetic equations are discretized on a five dimensional computational grid in phase space. The present implementation is a Method of Lines approach where the phase-space derivatives are discretized with finite differences and implicit backwards differencing formulas are used to advance the system in time. The fully nonlinear Boltzmann model is used for electrons. The neoclassical electric field is obtained by solving gyrokinetic Poisson equation with self-consistent poloidal variation. With our 4D ({psi}, {theta}, {epsilon}, {mu}) version of the TEMPEST code we compute radial particle and heat flux, the Geodesic-Acoustic Mode (GAM), and the development of neoclassical electric field, which we compare with neoclassical theory with a Lorentz collision model. The present work provides a numerical scheme and a new capability for self-consistently studying important aspects of neoclassical transport and rotations in toroidal magnetic fusion devices.

  7. Analysis of thermodiffusive cellular instabilities in continuum combustion fronts

    Science.gov (United States)

    Azizi, Hossein; Gurevich, Sebastian; Provatas, Nikolas

    2017-01-01

    We explore numerically the morphological patterns of thermodiffusive instabilities in combustion fronts with a continuum fuel source, within a range of Lewis numbers and ignition temperatures, focusing on the cellular regime. For this purpose, we generalize the recent model of Brailovsky et al. to include distinct process kinetics and reactant heterogeneity. The generalized model is derived analytically and validated with other established models in the limit of infinite Lewis number for zero-order and first-order kinetics. Cellular and dendritic instabilities are found at low Lewis numbers. These are studied using a dynamic adaptive mesh refinement technique that allows very large computational domains, thus allowing us to reduce finite-size effects that can affect or even preclude the emergence of these patterns. Our numerical linear stability analysis is consistent with the analytical results of Brailovsky et al. The distinct types of dynamics found in the vicinity of the critical Lewis number, ranging from steady-state cells to continued tip splitting and cell merging, are well described within the framework of thermodiffusive instabilities and are consistent with previous numerical studies. These types of dynamics are classified as "quasilinear" and characterized by low-amplitude cells that may be strongly affected by the mode selection mechanism and growth prescribed by the linear theory. Below this range of Lewis number, highly nonlinear effects become prominent and large-amplitude, complex cellular and seaweed dendritic morphologies emerge.

  8. Beams on Elastic Foundation. The Simplified Continuum Approach

    Directory of Open Access Journals (Sweden)

    Iancu-Bogdan Teodoru

    2009-01-01

    Full Text Available The key aspect in the design of flexible structural elements in contact with bearing soils is the way in which soil reaction, referred to qualitatively as soil’s reactive pressure (p, is assumed or accounted for in analysis. A magnitude and distribution of p might be preliminary assumed, or some mathematical relationships could be incorporated into the analysis itself, so that p is calculated as part of the analysis. In order to eliminate the bearing soil reaction as a variable in the problem solution, the simplified continuum approach is presented. This idealization provides much more information on the stress and deformation within soil mass compared to ordinary Winkler model, and it has the important advantage of the elimination of the necessity to determine the values of the foundation parameters, arbitrarily, because these values can be computed from the material properties (deformation modulus, Es, Poisson ratio, νs and depth of influence zone, H, along the beam for the soil. A numerical investigatio proach is also presented.

  9. A SUBMILLIMETER CONTINUUM SURVEY OF LOCAL DUST-OBSCURED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Chul [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Hwang, Ho Seong [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 02455 (Korea, Republic of); Lee, Gwang-Ho, E-mail: jclee@kasi.re.kr [Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2016-12-20

    We conduct a 350 μ m dust continuum emission survey of 17 dust-obscured galaxies (DOGs) at z = 0.05–0.08 with the Caltech Submillimeter Observatory (CSO). We detect 14 DOGs with S{sub 350μm} = 114–650 mJy and signal-to-noise > 3. By including two additional DOGs with submillimeter data in the literature, we are able to study dust content for a sample of 16 local DOGs, which consist of 12 bump and four power-law types. We determine their physical parameters with a two-component modified blackbody function model. The derived dust temperatures are in the range 57–122 K and 22–35 K for the warm and cold dust components, respectively. The total dust mass and the mass fraction of the warm dust component are 3–34 × 10{sup 7} M {sub ⊙} and 0.03%–2.52%, respectively. We compare these results with those of other submillimeter-detected infrared luminous galaxies. The bump DOGs, the majority of the DOG sample, show similar distributions of dust temperatures and total dust mass to the comparison sample. The power-law DOGs show a hint of smaller dust masses than other samples, but need to be tested with a larger sample. These findings support that the reason DOGs show heavy dust obscuration is not an overall amount of dust content, but probably the spatial distribution of dust therein.

  10. Gyrokinetic continuum simulations of turbulence in the Texas Helimak

    Science.gov (United States)

    Bernard, T. N.; Shi, E. L.; Hammett, G. W.; Hakim, A.; Taylor, E. I.

    2017-10-01

    We have used the Gkeyll code to perform 3x-2v full-f gyrokinetic continuum simulations of electrostatic plasma turbulence in the Texas Helimak. The Helimak is an open field-line experiment with magnetic curvature and shear. It is useful for validating numerical codes due to its extensive diagnostics and simple, helical geometry, which is similar to the scrape-off layer region of tokamaks. Interchange and drift-wave modes are the main turbulence mechanisms in the device, and potential biasing is applied to study the effect of velocity shear on turbulence reduction. With Gkeyll, we varied field-line pitch angle and simulated biased and unbiased cases to study different turbulent regimes and turbulence reduction. These are the first kinetic simulations of the Helimak and resulting plasma profiles agree fairly well with experimental data. This research demonstrates Gkeyll's progress towards 5D simulations of the SOL region of fusion devices. Supported by the U.S. DOE SCGSR program under contract DE-SC0014664, the Max-Planck/Princeton Center for Plasma Physics, the SciDAC Center for the Study of Plasma Microturbulence, and DOE contract DE-AC02-09CH11466.

  11. Psychiatric Management, Administration, and Leadership: a Continuum or Distinct Concepts?

    Science.gov (United States)

    Saeed, Sy Atezaz; Silver, Stuart; Buwalda, Victor J A; Khin, Eindra Khin; Petit, Jorge R; Mohyuddin, Farooq; Weinberg, Pamela; Merlino, Joseph P; Lekwauwa, Nena; Levin, Saul

    2017-10-06

    To clarify the relationship between the concepts of management, administration, and leadership in psychiatry. The authors provide a review of the conceptual evolution of administrative psychiatry and develop operational definitions of these three domains. Based upon their experiences, they discuss relevant core competencies and personal attributes. The authors found that the terms psychiatric management, psychiatric administration, and psychiatric leadership are often used interchangeably, yet they each have a different and distinct focus. Additionally, some in the field consider the concepts overlapping, existing on a continuum, while others draw distinct conceptual boundaries between these terms. Psychiatrists in leadership positions function in all three domains. While these are distinct concepts, the authors recommend that administrative psychiatrists integrate all three in their everyday work. The authors suggest the distinctions among these concepts should inform training and identify core competencies related to these distinctions. Mentoring should focus on the practical integration of the concepts of management, administration, and leadership in administrative psychiatry. The authors present a cohesive framework for future development of a curriculum for education and research.

  12. Fracture in a higher-order elastic continuum

    Science.gov (United States)

    Shi, M. X.; Huang, Y.; Hwang, K. C.

    2000-12-01

    We have obtained analytically the mode I and mode II full-field solutions for a semi-infinite crack in an infinite solid characterized by the higher-order elastic continuum theory. The theory is the limit of the strain gradient plasticity theory (Fleck, N.A., Hutchinson, J.W., 1997. Strain gradient plasticity. In: Hutchinson, J.W., Wu, T.Y. (Eds.), Advances in Applied Mechanics, vol. 33. Academic Press, New York, 295-361) with the plastic work hardening exponent n=1. It also represents the macroscopic behavior of cellular materials. The analytical solution shows the transition from remotely imposed classical K field to the asymptotic field near the crack tip over the internal material lengths associated with the stretch gradient and rotation gradient of deformation. It is established that the asymptotic crack tip fields have no domain of physical validity because the stress tractions have the incorrect sign within a zone on the order of internal material length l1 associated with the stretch gradient of deformation. This analytical full-field solution can be used as an important benchmark for the various finite elements developed for strain gradient plasticity.

  13. Drought effect on methane, nitrous oxide and carbon dioxide dynamics along boreal forest-mire ecotone

    Science.gov (United States)

    Ťupek, Boris; Minkkinen, Kari; Vesala, Timo; Kolari, Pasi; Starr, Mike; Alm, Jukka; Pumpanen, Jukka; Berninger, Frank; Laine, Jukka; Nikinmaa, Eero

    2013-04-01

    The effect of drought on CH4, N2O and CO2 dynamics of boreal forest and mires has been seldom observed in a continuum between xeric and wet habitats. Such a continuum includes a transitional zone between forests and mires which is frequently exposed to large soil moisture differences, but generally overlooked due to a relatively narrow extent. Although, it's known that CH4, N2O and CO2 dynamics are sensitive to soil moisture. We evaluated spatiotemporal effects of drought on CH4, N2O and CO2 dynamics in continuum of nine distinct forest/mire types. Soils changed from well-drained podzols to poorly-drained histosols and ground water raised downslope from the depth of 10 m in upland forests to 0.1 m in mires. Meteorological conditions, forest floor respiration, methane, and nitrous oxide flux data were collected during growing season of exceptionally wet (2004), intermediate (2005), and exceptionally dry (2006) year. The CH4, N2O and CO2 fluxes were studied by chamber methods. The seasonal median forest floor CH4, N2O, and CO2 dark fluxes between forest/mire types and between rainy, intermediate, and dry years varied from -0.07 to 1.68 mgCH4 m2 h-1, from 1.5 to 24.65 μgN2O m2 h-1, and from 0.26 to 0.76 gCO2 m2 h-1. The CH4 oxidation in upland forest and transitional types was similar between wet and dry years, though the CH4 production of mires was reduced in dry year. Probably due to low nitrification potential, larger soil water differences between years 2005 and 2006 did not seem to trigger corresponding changes in small N2O fluxes. The forest floor dark CO2 efflux during drought was in comparison to wetter periods significantly reduced in upland forest and transitional types, but stayed similar or even increased in mires. In the carbon rich soil of forest/mire transitions mainly soil CO2 efflux were sensitive to short term fluctuations between water level drawdown and water saturation, whereas CH4 and N2O fluxes changed minimally.

  14. National Forest Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — This theme shows the USFS national forest boundaries in the state. This data was acquired from the GIS coordinators at both the Chippewa National Forest and the...

  15. Forest Stand Age

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Source data for forest stand age were obtained from the USDA Forest Inventory and Analysis (FIA) DataMart and were projected for future scenarios based on selected...

  16. Biexcitonic bound and continuum states of homogeneously and inhomogeneously broadened exciton resonances

    DEFF Research Database (Denmark)

    Langbein, W.; Hvam, Jørn Märcher

    2002-01-01

    We investigate the influence of excitonic localization on the corresponding biexcitonic states in GaAs quantum wells by spectrally resolved four-wave mixing. With increasing localization, the biexciton binding energy increases, while the biexciton continuum shifts to higher energies....... The localization leads to an inhomogeneous broadening of the biexciton binding energy and the biexciton continuum edge. Simultaneously, the oscillator strength of the biexciton continuum-edge is reduced. This is interpreted as a result of the different localization of biexcitonic and excitonic states by the random...

  17. Non-classical solutions of a continuum model for rock descriptions

    Directory of Open Access Journals (Sweden)

    Mikhail A. Guzev

    2014-06-01

    Full Text Available The strain-gradient and non-Euclidean continuum theories are employed for construction of non-classical solutions of continuum models. The linear approximation of both models' results in identical structures in terms of their kinematic and stress characteristics. The solutions obtained in this study exhibit a critical behaviour with respect to the external loading parameter. The conclusions are obtained based on an investigation of the solution for the scalar curvature in the non-Euclidean continuum theory. The proposed analysis enables us to use different theoretical approaches for description of rock critical behaviour under different loading conditions.

  18. Size dependent surface energy of nanoplates: Molecular dynamics and nanoscale continuum theory correlations

    Science.gov (United States)

    Jamshidian, M.; Dehghani, A.; Talaei, M. S.; Rabczuk, T.

    2018-01-01

    A nanoscale gradient continuum theory along with molecular dynamics simulations are employed to investigate the size-dependent surface energy of nanoplates. Molecular dynamics simulations reveal that upon nanoplate thickness reduction, the redistribution of surface energy density along thickness direction causes the decrease of the surface energy of nanoplate free surfaces. Via introducing a calibration benchmark, the length scale model parameter of the gradient continuum theory is methodically determined. The calibrated continuum theory is shown to well predict the size-dependent surface energy and the associated redistribution of surface energy density within nanoplates.

  19. Controlling multipolar radiation with symmetries for electromagnetic bound states in the continuum

    Science.gov (United States)

    Lepetit, Thomas; Kanté, Boubacar

    2014-12-01

    Interferences in open systems embedded in a continuum can lead to states that are bound within the continuum itself. An electromagnetic state that naturally decays becomes bound at a unique point in phase space. We demonstrate the striking occurrence of multiple such peculiar states in coupled deep subwavelength resonators. The bound states in the continuum originate from the control of multipolar radiation and their symmetries. The architectures investigated here, using all-dielectric resonators, constitute a flexible and readily achievable platform for applications requiring strong light-matter interaction and light localization.

  20. Accidental bound states in the continuum in an open Sinai billiard

    Energy Technology Data Exchange (ETDEWEB)

    Pilipchuk, A.S. [Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk (Russian Federation); Siberian Federal University, 660080 Krasnoyarsk (Russian Federation); Sadreev, A.F., E-mail: almas@tnp.krasn.ru [Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk (Russian Federation)

    2017-02-19

    The fundamental mechanism of the bound states in the continuum is the full destructive interference of two resonances when two eigenlevels of the closed system are crossing. There is, however, a wide class of quantum chaotic systems which display only avoided crossings of eigenlevels. As an example of such a system we consider the Sinai billiard coupled with two semi-infinite waveguides. We show that notwithstanding the absence of degeneracy bound states in the continuum occur due to accidental decoupling of the eigenstates of the billiard from the waveguides. - Highlights: • Bound states in the continuum in open chaotic billiards occur to accidental vanishing of coupling of eigenstate of billiard with waveguides.

  1. West Virginia's Forests 2008

    Science.gov (United States)

    Richard H. Widmann; Gregory W. Cook; Charles J. Barnett; Brett J. Butler; Douglas M. Griffith; Mark A. Hatfield; Cassandra M. Kurtz; Randall S. Morin; W. Keith Moser; Charles H. Perry; Ronald J. Piva; Rachel Riemann; Christopher W. Woodall

    2012-01-01

    The first full annual inventory of West Virginia's forests reports 12.0 million acres of forest land or 78 percent of the State's land area. The area of forest land has changed little since 2000. Of this land, 7.2 million acres (60 percent) are held by family forest owners. The current growing-stock inventory is 25 billion cubic feet--12 percent more than in...

  2. Tennessee's Forests, 2004

    Science.gov (United States)

    Christopher M. Oswalt; Sonja N. Oswalt; Tony G. Johnson; James L. Chamberlain; KaDonna C. Randolph; John W. Coulston

    2009-01-01

    Forest land area in Tennessee amounted to 13.78 million acres. About 125 different species, mostly hardwood, account for an estimated 22.6 billion cubic feet of all growing-stock volume on timberland in the State. Hardwood forest types occupy the vast majority of the State's forest land, and oak-hickory is the dominant forest-type group, accounting for about 10.1...

  3. Maine's forests 2008

    Science.gov (United States)

    George L. McCaskill; William H. McWilliams; Charles J. Barnett; Brett J. Butler; Mark A. Hatfield; Cassandra M. Kurtz; Randall S. Morin; W. Keith Moser; Charles H. Perry; Christopher W. Woodall

    2011-01-01

    The second annual inventory of Maine's forests was completed in 2008 after more than 3,160 forested plots were measured. Forest land occupies almost 17.7 million acres, which represents 82 percent of the total land area of Maine. The dominant forest-type groups are maple/beech/yellow birch, spruce/fir, white/red/jack pine, and aspen/white birch. Statewide volume...

  4. Southern Forests: a Journal of Forest Science

    African Journals Online (AJOL)

    Temperate forest dynamics and carbon storage: A 26-year case study from Orange Kloof Forest, Cape Peninsula, South Africa · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Anabelle W. Cardoso, Jeremy J. Midgley, M. Timm Hoffman, Coert J. Geldenhuys, 297–303 ...

  5. Dipterocarpaceae: forest fires and forest recovery

    NARCIS (Netherlands)

    Priadjati, A.

    2002-01-01

    One of the serious problems Indonesia is facing today is deforestation. Forests have been playing a very important role in Indonesia as the main natural resources for the economic growth of the country. Large areas of tropical forests, worldwide

  6. Integrating silviculture, forest management, and forest policy

    Science.gov (United States)

    Chadwick D. Oliver

    1997-01-01

    Much progress has been made in developing and implementing individual silvicultural operations such as regeneration, thinning, and harvesting by various means. Similarly, foresters have made progress at managing flows of timber and other commodity values. Present concern that forests provide an even greater variety of commodity and non-commodity values can be...

  7. Forest resources of the Kootenai National Forest

    Science.gov (United States)

    Andrea M. Wilson; Patrick D. Miles

    2000-01-01

    THe Interior West Resource Inventory, Monitoring, and Evaluation (IWRIME) Program of the USDA Forest Service, Rocky Mountain Research Station (formerly known as the Intermountain Research Station), as part of its national Forest Inventory and Analysis (FIA) duties, entered into a cooperative agreement with the Northern Region (Region 1) for the inventory of its...

  8. From forest struggles to forest citizens? Joint Forest Management in the unquiet woods of India's Jharkhand

    OpenAIRE

    S Corbridge; Jewitt, S.

    1997-01-01

    The government of India has embraced joint forest management as a key strategy for dealing with forest degradation and forest employment issues in the 1990s. This represents a significant movement away from the forest reservation policies that held sway from 1947 to 1988 and which criminalised many local forest users. In this paper we consider the role played by forest struggles and forest intellectuals (notably Guha and Gadgil) in the rewriting of India's forest policies. We also evaluate th...

  9. Forests of Iowa, 2013

    Science.gov (United States)

    Mark D. Nelson; Matt. Brewer

    2014-01-01

    This resource update provides an overview of forest resources in Iowa based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Northern Research Station in cooperation with the Iowa Department of Natural Resources. Estimates are based on field data collected using the FIA annualized sample design and are updated...

  10. Forests of Indiana, 2013

    Science.gov (United States)

    Dale D. Gormanson

    2014-01-01

    This resource update provides an overview of forest resources in Indiana based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Northern Research Station in cooperation with the Indiana Department of Natural Resources. Estimates are based on field data collected using the FIA annualized strategic sample design and...

  11. Forests of Iowa, 2014

    Science.gov (United States)

    Mark D. Nelson; Matt Brewer; Brett J. Butler; Scott A. Pugh

    2015-01-01

    This resource update provides an overview of forest resources in Iowa based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Northern Research Station in cooperation with the Iowa Department of Natural Resources. Estimates are based on field data collected using the FIA annualized sample design and are updated...

  12. Forecasts of forest conditions

    Science.gov (United States)

    Robert Huggett; David N. Wear; Ruhong Li; John Coulston; Shan Liu

    2013-01-01

    Key FindingsAmong the five forest management types, only planted pine is expected to increase in area. In 2010 planted pine comprised 19 percent of southern forests. By 2060, planted pine is forecasted to comprise somewhere between 24 and 36 percent of forest area.Although predicted rates of change vary, all forecasts reveal...

  13. Minnesota's forest resources, 2006

    Science.gov (United States)

    P.D. Miles; D. Heinzen

    2007-01-01

    This publication provides an overview of forest resource attributes for Minnesota based on an annual inventory conducted by the Forest Inventory and Analysis program at the Northern Research Station of the U.S. Forest Service. These annual estimates, along with web-posted core tables, will be updated annually. For more information regarding past inventory reports for...

  14. Forest-fire models

    Science.gov (United States)

    Haiganoush Preisler; Alan Ager

    2013-01-01

    For applied mathematicians forest fire models refer mainly to a non-linear dynamic system often used to simulate spread of fire. For forest managers forest fire models may pertain to any of the three phases of fire management: prefire planning (fire risk models), fire suppression (fire behavior models), and postfire evaluation (fire effects and economic models). In...

  15. Forests of Wisconsin, 2016

    Science.gov (United States)

    Cassandra M. Kurtz

    2017-01-01

    This resource update provides an overview of forest resources in Wisconsin based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Northern Research Station in cooperation with the Wisconsin Department of Natural Resources (WDNR). Data estimates are based on field data collected using the FIA annualized sample...

  16. Forest resources and conditions

    Science.gov (United States)

    William H. McWilliams; Linda S. Heath; Gordon C. Reese; Thomas L. Schmidt

    2000-01-01

    The forests of the northern United States support a rich mix of floral and faunal communities that provide inestimable benefits to society. Today's forests face a range of biotic and abiotic stressors, not the least of which may be environmental change. This chapter reviews the compositional traits of presettlement forests and traces the major land use patterns...

  17. Forests of Oklahoma, 2014

    Science.gov (United States)

    S. Lambert; K. Randolph; J. Cooper

    2015-01-01

    This resource update provides an overview of forest resources in Oklahoma based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Southern Research Station, in cooperation with Oklahoma Forestry Services. Estimates are based on field data collected using the FIA annualized sample design and are updated yearly,...

  18. Forest resources of the Forest resources of the Apache-Sitgreaves National Forest

    Science.gov (United States)

    Paul Rogers

    2008-01-01

    The Interior West Forest Inventory and Analysis (IWFIA) program of the USDA Forest Service, Rocky Mountain Research Station, as part of its national Forest Inventory and Analysis (FIA) duties, conducted forest resource inventories of the Southwestern Region (Region 3) National Forests. This report presents highlights of the Apache-Sitgreaves National Forest...

  19. Non-equilibrium stochastic dynamics in continuum: The free case

    Directory of Open Access Journals (Sweden)

    Y.Kondratiev

    2008-12-01

    Full Text Available We study the problem of identification of a proper state-space for the stochastic dynamics of free particles in continuum, with their possible birth and death. In this dynamics, the motion of each separate particle is described by a fixed Markov process M on a Riemannian manifold X. The main problem arising here is a possible collapse of the system, in the sense that, though the initial configuration of particles is locally finite, there could exist a compact set in X such that, with probability one, infinitely many particles will arrive at this set at some time t>0. We assume that X has infinite volume and, for each α���1, we consider the set Θα of all infinite configurations in X for which the number of particles in a compact set is bounded by a constant times the α-th power of the volume of the set. We find quite general conditions on the process M which guarantee that the corresponding infinite particle process can start at each configuration from Θα, will never leave Θα, and has cadlag (or, even, continuous sample paths in the vague topology. We consider the following examples of applications of our results: Brownian motion on the configuration space, free Glauber dynamics on the configuration space (or a birth-and-death process in X, and free Kawasaki dynamics on the configuration space. We also show that if X=Rd, then for a wide class of starting distributions, the (non-equilibrium free Glauber dynamics is a scaling limit of (non-equilibrium free Kawasaki dynamics.

  20. Phosphorus Dynamics along River Continuum during Typhoon Storm Events

    Directory of Open Access Journals (Sweden)

    Ming Fai Chow

    2017-07-01

    Full Text Available Information on riverine phosphorus (P dynamics during typhoon storm events remains scarce in subtropical regions. Thus, this study investigates the spatial and temporal dynamics of riverine phosphorus in a headwater catchment during three typhoon events. Continuous sampling (3 h intervals of stormwater samples and discharge data were conducted at five locations, which represent the upstream, transitional zone, and downstream areas of the main inflow river. The results revealed that the average event mean concentrations (EMCs for total dissolved phosphorus (TDP and particulate phosphorus (PP in the upstream catchment of Fei-Tsui reservoir were 15.66 μg/L and 11.94 μg/L, respectively. There was at least a 1.3-fold increase in flow-weighted concentrations of TDP and PP from the upper to lower reaches of the main stream. PP and TDP were transported either in clockwise or anticlockwise directions, depending on storm intensity and source. The transport of TDP was primarily regulated by the subsurface flow during the storm event. Soluble reactive phosphorus (SRP contributes more than 50% of the TDP load in moderate storms, while extreme storms supply a greater dissolved organic phosphorus (DOP load into the stream. TDP accounted for approximately 50% of TP load during typhoon storms. Mobilization of all P forms was observed from upstream to downstream of the river, except for DOP. A decrease of DOP load on passing downstream may reflect the change in phosphorus form along the river continuum. Peak discharge and antecedent dry days are correlated positively with P fluxes, indicating that river bank erosion and re-suspension of within-channel sediment are the dominant pathways of P during typhoon storm periods.

  1. The Novice-Expert Continuum in Astronomy Knowledge

    Science.gov (United States)

    Bryce, T. G. K.; Blown, E. J.

    2012-03-01

    The nature of expertise in astronomy was investigated across a broad spectrum of ages and experience in China and New Zealand. Five hypotheses (capable of quantification and statistical analysis) were used to probe types of expertise identified by previous researchers: (a) domain-specific knowledge-skill in the use of scientific vocabulary and language and recognising relationships between concepts in linguistic and schematic forms; (b) higher-order theory in terms of conceptual structure and enriched scientific knowledge and reasoning; with an expectation of cultural similarity. There were 993 participants in all, age 3-80 years, including 68 junior school pupils; 68 pre-school pupils; 112 middle-school students; 109 high-school students; 79 physics undergraduates; 60 parents; 136 pre-service primary teachers; 131 pre-service secondary teachers; 72 primary teachers; 78 secondary teachers; 50 amateur astronomers and astronomy educators; and 30 astronomers and physicists; with approximately equal numbers of each group in both cultures; and of boys and girls in the case of children. For them, the methodology utilised Piagetian interviews with three media (verbal language, drawing, play-dough modelling), and for adults a questionnaire inviting responses in writing and drawing was used. The data from each group were categorised into ordinal scales and then analysed by means of Kolmogorov-Smirnov two-sample tests. The findings supported the hypotheses with evidence of all forms of expertise increasing with experience in both cultures (α level 0.05). The relative gains, overlaps and deficits in expertise across the novice-expert continuum are explored in detail.

  2. Integrated Information Systems Across the Weather-Climate Continuum

    Science.gov (United States)

    Pulwarty, R. S.; Higgins, W.; Nierenberg, C.; Trtanj, J.

    2015-12-01

    The increasing demand for well-organized (integrated) end-to-end research-based information has been highlighted in several National Academy studies, in IPCC Reports (such as the SREX and Fifth Assessment) and by public and private constituents. Such information constitutes a significant component of the "environmental intelligence" needed to address myriad societal needs for early warning and resilience across the weather-climate continuum. The next generation of climate research in service to the nation requires an even more visible, authoritative and robust commitment to scientific integration in support of adaptive information systems that address emergent risks and inform longer-term resilience strategies. A proven mechanism for resourcing such requirements is to demonstrate vision, purpose, support, connection to constituencies, and prototypes of desired capabilities. In this presentation we will discuss efforts at NOAA, and elsewhere, that: Improve information on how changes in extremes in key phenomena such as drought, floods, and heat stress impact management decisions for resource planning and disaster risk reduction Develop regional integrated information systems to address these emergent challenges, that integrate observations, monitoring and prediction, impacts assessments and scenarios, preparedness and adaptation, and coordination and capacity-building. Such systems, as illustrated through efforts such as NIDIS, have strengthened the integration across the foundational research enterprise (through for instance, RISAs, Modeling Analysis Predictions and Projections) by increasing agility for responding to emergent risks. The recently- initiated Climate Services Information System, in support of the WMO Global Framework for Climate Services draws on the above models and will be introduced during the presentation.

  3. A double continuum hydrological model for glacier applications

    Directory of Open Access Journals (Sweden)

    B. de Fleurian

    2014-01-01

    Full Text Available The flow of glaciers and ice streams is strongly influenced by the presence of water at the interface between ice and bed. In this paper, a hydrological model evaluating the subglacial water pressure is developed with the final aim of estimating the sliding velocities of glaciers. The global model fully couples the subglacial hydrology and the ice dynamics through a water-dependent friction law. The hydrological part of the model follows a double continuum approach which relies on the use of porous layers to compute water heads in inefficient and efficient drainage systems. This method has the advantage of a relatively low computational cost that would allow its application to large ice bodies such as Greenland or Antarctica ice streams. The hydrological model has been implemented in the finite element code Elmer/Ice, which simultaneously computes the ice flow. Herein, we present an application to the Haut Glacier d'Arolla for which we have a large number of observations, making it well suited to the purpose of validating both the hydrology and ice flow model components. The selection of hydrological, under-determined parameters from a wide range of values is guided by comparison of the model results with available glacier observations. Once this selection has been performed, the coupling between subglacial hydrology and ice dynamics is undertaken throughout a melt season. Results indicate that this new modelling approach for subglacial hydrology is able to reproduce the broad temporal and spatial patterns of the observed subglacial hydrological system. Furthermore, the coupling with the ice dynamics shows good agreement with the observed spring speed-up.

  4. Understanding Stoichiometric Controls in Nutrient Processing Along the River Continuum

    Science.gov (United States)

    Garayburu-Caruso, V. A.; Gonzalez-Pinzon, R.; Van Horn, D. J.; Covino, T. P.

    2016-12-01

    Eutrophication is the second most common cause of water impairment across the U.S. Nutrient retention in streams is controlled by physical and biochemical processes, including biomass availability and stoichiometric limitations. Decoupling the interactions between hydrology, nutrient supply and biogeochemical processes remains challenging for the scientific community due to lack of mechanistic understanding. Consequently, more knowledge regarding optimal controls for nutrient retention is needed to implement better management and restoration practices. We conducted column experiments to investigate how stoichiometric limitations influence nutrient spiraling in shallow sediment-water interactions along representative sites of the Jemez River-Rio Grande continuum (which spans eight stream orders), in New Mexico, USA. In each stream order we incubated six columns packed with different sediments (i.e., Silica Cone Density Sand ASTM D 1556 (0.075-2.00 mm), gravel (>2mm) and native sediments) from each site for three months. We performed two laboratory tracer experiments using columns of each substrate under identical flow conditions. In the first experiment we added a short-term pulse of reactive and conservative tracers (i.e. NaNO3 and NaBr). In the second experiment we added a short-term pulse of NaBr and nutrients following Redfield's ratio (106C:16N:1P). We estimated uptake kinetics using the Tracer Additions for Spiraling Curve Characterization (TASCC) method and evaluated how ideal stoichiometric conditions controlled efficient nutrient retention along fluvial networks. Our results suggest that biological uptake of nitrate is limited by nitrogen in headwater streams and by phosphorus and carbon in larger stream orders.

  5. Beyond R & D: Market Impact, Continuum Magazine, Summer 2016 / Issue 9

    Energy Technology Data Exchange (ETDEWEB)

    2016-07-01

    This issue of NREL's Continuum Magazine covers the depth and breadth of the laboratory's work to bridge scientific discovery and market adoption by helping technologies move from research through development, demonstration, and deployment.

  6. Numerical Modelling and Damage Assessment of Rotary Wing Aircraft Cabin Door Using Continuum Damage Mechanics Model

    Science.gov (United States)

    Boyina, Gangadhara Rao T.; Rayavarapu, Vijaya Kumar; V. V., Subba Rao

    2017-02-01

    The prediction of ultimate strength remains the main challenge in the simulation of the mechanical response of composite structures. This paper examines continuum damage model to predict the strength and size effects for deformation and failure response of polymer composite laminates when subjected to complex state of stress. The paper also considers how the overall results of the exercise can be applied in design applications. The continuum damage model is described and the resulting prediction of size effects are compared against the standard benchmark solutions. The stress analysis for strength prediction of rotary wing aircraft cabin door is carried out. The goal of this study is to extend the proposed continuum damage model such that it can be accurately predict the failure around stress concentration regions. The finite element-based continuum damage mechanics model can be applied to the structures and components of arbitrary configurations where analytical solutions could not be developed.

  7. Gas-Kinetic Computational Algorithms for Hypersonic Flows in Continuum and Transitional Regimes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project explores two gas-kinetic computational algorithms for simulation of hypersonic flows in both continuum and transitional regimes. One is the...

  8. An online intervention using information on the mental health-mental illness continuum to reduce stigma.

    Science.gov (United States)

    Schomerus, G; Angermeyer, M C; Baumeister, S E; Stolzenburg, S; Link, B G; Phelan, J C

    2016-02-01

    A core component of stigma is being set apart as a distinct, dichotomously different kind of person. We examine whether information on a continuum from mental health to mental illness reduces stigma. Online survey experiment in a quota sample matching the German population for age, gender and region (n=1679). Participants randomly received information on either (1) a continuum, (2) a strict dichotomy of mental health and mental illness, or (3) no information. We elicited continuity beliefs and stigma toward a person with schizophrenia or depression. The continuum intervention decreased perceived difference by 0.19 standard deviations (SD, Pmental illness can be improved by providing information on a mental health-mental illness continuum. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  9. Ultrasensitive optical absorption in graphene based on bound states in the continuum

    National Research Council Canada - National Science Library

    Zhang, Mingda; Zhang, Xiangdong

    2015-01-01

    We have designed a sphere-graphene-slab structure so that the electromagnetic wave can be well confined in the graphene due to the formation of a bound state in a continuum (BIC) of radiation modes...

  10. Evaluation of Multimedia Authoring Instruction Based in a Behaviorist-Cognitive-Constructivist Continuum.

    Science.gov (United States)

    Sherry, Annette C.

    1998-01-01

    This evaluative case study examines the learning experiences of graduate students studying effective multimedia authoring. Continuum-based instructional design, behaviorism, cognitivism, constructivism, collaboration, the role of a matrix, transfer of training, and qualitative and quantitative results are discussed. (LRW)

  11. The forest Gribskov, Denmark

    DEFF Research Database (Denmark)

    Overballe-Petersen, Mette V; Raulund-Rasmussen, Karsten; Buttenschøn, Rita M.

    2014-01-01

    Knowledge of forest history is crucial for understanding the processes, structures, functions and current status of forest ecosystems. An enhanced understanding of the long history of disturbance factors affecting forest development and thereby the present state of the forest is particularly...... valuable when working with forest management, conservation and restoration. Integrating the legacies of past disturbances-natural as well as anthropogenic-into conservation and management strategies is likely to favour natural values and ecosystem services. A case-study in Gribskov, Denmark, using...

  12. Fractional Diffusion Equations for Lattice and Continuum: Grünwald-Letnikov Differences and Derivatives Approach

    OpenAIRE

    Tarasov, Vasily E.

    2014-01-01

    Fractional diffusion equations for three-dimensional lattice models based on fractional-order differences of the Grünwald-Letnikov type are suggested. These lattice fractional diffusion equations contain difference operators that describe long-range jumps from one lattice site to another. In continuum limit, the suggested lattice diffusion equations with noninteger order differences give the diffusion equations with the Grünwald-Letnikov fractional derivatives for continuum. We propose a cons...

  13. Concurrent atomistic and continuum simulation of bi-crystal strontium titanate with tilt grain boundary

    OpenAIRE

    Yang, Shengfeng; Chen, Youping

    2015-01-01

    In this paper, we present the development of a concurrent atomistic–continuum (CAC) methodology for simulation of the grain boundary (GB) structures and their interaction with other defects in ionic materials. Simulation results show that the CAC simulation allows a smooth passage of cracks through the atomistic–continuum interface without the need for additional constitutive rules or special numerical treatment; both the atomic-scale structures and the energies of the four different [001] ti...

  14. Total joint arthroplasty: practice variation of physiotherapy across the continuum of care in Alberta

    OpenAIRE

    Jones, C. Allyson; Martin, Ruben San; Westby, Marie D.; Lauren A. Beaupre

    2016-01-01

    Background Comprehensive and timely rehabilitation for total joint arthroplasty (TJA) is needed to maximize recovery from this elective surgical procedure for hip and knee arthritis. Administrative data do not capture the variation of treatment for rehabilitation across the continuum of care for TJA, so we conducted a survey for physiotherapists to report practice for TJA across the continuum of care. The primary objective was to describe the reported practice of physiotherapy for TJA across ...

  15. White light continuum generation in sapphire using two-coloured femtosecond laser pulses

    OpenAIRE

    Čepėnas, Augustas

    2017-01-01

    A wide spectrum of laser radiation is useful for two reasons: wider spectrum allows generation of shorter laser pulses, meanwhile, in pump-probe spectroscopy it is prefered to cover the largest possible spectral range with the same source. This work explores white light continuum generation using two-colored (wavelength of 1030 nm and 515 nm) femtosecond laser pulses. Combining these two white light continuums should expand radiation spectrum. However, this research shows that white light con...

  16. Quantum secure direct communication of digital and analog signals using continuum coherent states

    Science.gov (United States)

    Guerra, Antônio Geovan de Araújo Holanda; Rios, Francisco Franklin Sousa; Ramos, Rubens Viana

    2016-11-01

    In this work, we present optical schemes for secure direct quantum communication of digital and analog signals using continuum coherent states and frequency-dependent phase modulation. The main advantages of the proposed schemes are that they do not use entangled states and they can be implemented with today technology. The theory of quantum interference of continuum coherent state is described, and the optical setups for secure direct communication are presented and their securities are discussed.

  17. Linkages to Survival : : An Examination of the Reproductive and Maternal Health Continuum of Care

    OpenAIRE

    McDougal, Lotus Padma

    2014-01-01

    Background : Each year, an estimated 287,000 women and 3 million newborns in low and middle income countries die of largely preventable causes. Global organizations have adopted a continuum of care model to mitigate these deaths, in which health interventions are conceptualized as a continuous stream of services. This approach remains untested in practice, however. This research aims to explore utilization and linkages within the reproductive and maternal health continuum of care (RMH CoC), a...

  18. Public Preferences Across Europe for Different Forest Stand Types as Sites for Recreation

    Directory of Open Access Journals (Sweden)

    David M. Edwards

    2012-03-01

    Full Text Available A Delphi survey involving experts in forest preference research was carried out to derive scores for the recreational value of 240 forest stand types across Europe. The survey was organized around four regional panels: Great Britain, Nordic Region, Central Europe, and Iberia. In each region, 60 forest stand types were defined according to five forest management alternatives (FMAs on a continuum of management intensity, four phases of development (establishment, young, medium, and adult, and three tree species types (conifer, broadleaved, and mixed stands of conifer and broadleaved. The resulting scores were examined using conjoint analysis to determine the relative importance of the three structural attributes (FMA, phase of development, and tree species type, and each level or component of the attributes. The findings quantify the extent to which forest visitors prefer a degree of management to unmanaged forest nature reserves across the four regions. Phase of development was shown to make the highest contribution to the recreational value of forests while the contribution of tree species type was shown to be relatively unimportant. While the results are indicative, they provide evidence to support long-term retention and low-impact silviculture in forests where recreation is a primary objective of management.

  19. European mixed forests

    DEFF Research Database (Denmark)

    Bravo-Oviedo, Andres; Pretzsch, Hans; Ammer, Christian

    2014-01-01

    Aim of study: We aim at (i) developing a reference definition of mixed forests in order to harmonize comparative research in mixed forests and (ii) review the research perspectives in mixed forests. Area of study: The definition is developed in Europe but can be tested worldwide. Material...... and Methods: Review of existent definitions of mixed forests based and literature review encompassing dynamics, management and economic valuation of mixed forests. Main results: A mixed forest is defined as a forest unit, excluding linear formations, where at least two tree species coexist at any...... developmental stage, sharing common resources (light, water, and/or soil nutrients). The presence of each of the component species is normally quantified as a proportion of the number of stems or of basal area, although volume, biomass or canopy cover as well as proportions by occupied stand area may be used...

  20. Kinematics optimization and static analysis of a modular continuum robot used for minimally invasive surgery.

    Science.gov (United States)

    Qi, Fei; Ju, Feng; Bai, Dong Ming; Chen, Bai

    2018-02-01

    For the outstanding compliance and dexterity of continuum robot, it is increasingly used in minimally invasive surgery. The wide workspace, high dexterity and strong payload capacity are essential to the continuum robot. In this article, we investigate the workspace of a cable-driven continuum robot that we proposed. The influence of section number on the workspace is discussed when robot is operated in narrow environment. Meanwhile, the structural parameters of this continuum robot are optimized to achieve better kinematic performance. Moreover, an indicator based on the dexterous solid angle for evaluating the dexterity of robot is introduced and the distal end dexterity is compared for the three-section continuum robot with different range of variables. Results imply that the wider range of variables achieve the better dexterity. Finally, the static model of robot based on the principle of virtual work is derived to analyze the relationship between the bending shape deformation and the driven force. The simulations and experiments for plane and spatial motions are conducted to validate the feasibility of model, respectively. Results of this article can contribute to the real-time control and movement and can be a design reference for cable-driven continuum robot.

  1. Kinematics and the implementation of an elephant's trunk manipulator and other continuum style robots

    Science.gov (United States)

    Hannan, Michael W.; Walker, Ian D.

    2003-01-01

    Traditionally, robot manipulators have been a simple arrangement of a small number of serially connected links and actuated joints. Though these manipulators prove to be very effective for many tasks, they are not without their limitations, due mainly to their lack of maneuverability or total degrees of freedom. Continuum style (i.e., continuous "back-bone") robots, on the other hand, exhibit a wide range of maneuverability, and can have a large number of degrees of freedom. The motion of continuum style robots is generated through the bending of the robot over a given section; unlike traditional robots where the motion occurs in discrete locations, i.e., joints. The motion of continuum manipulators is often compared to that of biological manipulators such as trunks and tentacles. These continuum style robots can achieve motions that could only be obtainable by a conventionally designed robot with many more degrees of freedom. In this paper we present a detailed formulation and explanation of a novel kinematic model for continuum style robots. The design, construction, and implementation of our continuum style robot called the elephant trunk manipulator is presented. Experimental results are then provided to verify the legitimacy of our model when applied to our physical manipulator. We also provide a set of obstacle avoidance experiments that help to exhibit the practical implementation of both our manipulator and our kinematic model. c2003 Wiley Periodicals, Inc.

  2. The utility of continuum simulations for direct current and microwave microplasmas

    Science.gov (United States)

    Ayyaswamy, Venkattraman; Alamatsaz, Arghavan; Verma, Abhishek Kumer

    2017-10-01

    State-of-the-art microplasma devices have contributed to several challenges that require a fundamental understanding of the various mechanisms involved in order to achieve optimal operation for a given application. In this context, the role of computations cannot be stressed enough. Historically, the computational techniques used for simulating plasmas belong to two categories `` continuum/fluid and kinetic methods. The primary goal of the current work is to perform an exhaustive comparison of continuum and kinetic simulations for a range of operating conditions. Kinetic simulations using the particle-in-cell with Monte Carlo collisions (PIC-MCC) method and continuum simulations using the full-momentum equation are performed at various operating conditions. It is shown that using the electron energy distribution function (EEDF) predicted by BOLSIG+ in continuum simulations of direct current microplasmas leads to a significant under-prediction of plasma densities. The discrepancy between kinetic and continuum simulations is attributed to the presence of hot electrons created as a result of secondary emission. On the other hand, continuum simulations performed for a microwave microplasma operating at 0.5 GHz showed excellent agreement with kinetic simulations.

  3. Dynamics Modeling of a Continuum Robotic Arm with a Contact Point in Planar Grasp

    Directory of Open Access Journals (Sweden)

    Mohammad Dehghani

    2014-01-01

    Full Text Available Grasping objects by continuum arms or fingers is a new field of interest in robotics. Continuum manipulators have the advantages of high adaptation and compatibility with respect to the object shape. However, due to their extremely nonlinear behavior and infinite degrees of freedom, continuum arms cannot be easily modeled. In fact, dynamics modeling of continuum robotic manipulators is state-of-the-art. Using the exact modeling approaches, such as theory of Cosserat rod, the resulting models are either too much time-taking for computation or numerically unstable. Thus, such models are not suitable for applications such as real-time control. However, based on realistic assumptions and using some approximations, these systems can be modeled with reasonable computational efforts. In this paper, a planar continuum robotic arm is modeled, considering its backbone as two circular arcs. In order to simulate finger grasping, the continuum arm experiences a point-force along its body. Finally, the results are validated using obtained experimental data.

  4. A Cyclical Approach to Continuum Modeling: A Conceptual Model of Diabetic Foot Care

    Directory of Open Access Journals (Sweden)

    Martha L. Carvour

    2017-12-01

    Full Text Available “Cascade” or “continuum” models have been developed for a number of diseases and conditions. These models define the desired, successive steps in care for that disease or condition and depict the proportion of the population that has completed each step. These models may be used to compare care across subgroups or populations and to identify and evaluate interventions intended to improve outcomes on the population level. Previous cascade or continuum models have been limited by several factors. These models are best suited to processes with stepwise outcomes—such as screening, diagnosis, and treatment—with a single defined outcome (e.g., treatment or cure for each member of the population. However, continuum modeling is not well developed for complex processes with non-sequential or recurring steps or those without singular outcomes. As shown here using the example of diabetic foot care, the concept of continuum modeling may be re-envisioned with a cyclical approach. Cyclical continuum modeling may permit incorporation of non-sequential and recurring steps into a single continuum, while recognizing the presence of multiple desirable outcomes within the population. Cyclical models may simultaneously represent the distribution of clinical severity and clinical resource use across a population, thereby extending the benefits of traditional continuum models to complex processes for which population-based monitoring is desired. The models may also support communication with other stakeholders in the process of care, including health care providers and patients.

  5. Benchmark continuum and kinetic simulations of argon microplasmas in the direct current and microwave regimes

    Science.gov (United States)

    Verma, Abhishek Kumar; Alamatsaz, Arghavan; Venkattraman, Ayyaswamy

    2017-10-01

    This study presents benchmark comparisons between continuum and kinetic simulations of argon microplasmas operating in the direct current and microwave regimes. Kinetic simulations using the particle-in-cell with Monte Carlo collisions (PIC-MCC) method and continuum simulations using the full-momentum equation for both ions and electrons are performed at various operating conditions in order to study the influence of product of pressure and gap size, pd (for a given gap size), influence of gap size (for a given value of pd) and operating frequency. It is shown that using the electron energy distribution function (EEDF) predicted by zero-dimensional Boltzmann solvers (such as BOLSIG+) in continuum simulations of direct current microplasmas leads to a significant under-prediction of plasma number densities with continuum simulations based on the Maxwellian EEDF performing better particularly for higher values of pd. The discrepancy between kinetic and continuum simulations is attributed to the presence of hot electrons created as a result of secondary emission and subsequent acceleration in the sheath. On the other hand, simulations performed for argon microwave microplasmas operating at 0.5 GHz, 0.8 GHz, 2 GHz and 4 GHz demonstrated that continuum simulations performed using the rate constants from BOLSIG+  showed excellent agreement with kinetic simulations for the plasma density profiles in spite of over-predicting the voltage/power required to achieve a given plasma density.

  6. Severe Brain Injury in Massachusetts: Assessing the Continuum of Care.

    Science.gov (United States)

    Lorenz, Laura; Katz, Gabrielle

    2015-12-10

    Acquired brain injury (ABI) is a major public health problem in Massachusetts (Hackman et al, 2014) and includes traumatic brain injury (TBI), stroke, ABI-related infectious diseases, metabolic disorders affecting the central nervous system (brain and spinal cord), and brain tumor. Advances in emergency medical care and neurosurgery mean that more people are surviving severe traumatic brain injury (Trexler et al, 2014). Yet many patients with severe TBI in particular, are not receiving inpatient services after initial treatment (Hackman et al, 2014; CDC, 2014) or later that are known to be effective (Malec & Kean, 2015; Lewis & Horn, 2015; BI Commission, 2011; Kolakowsky-Hayner et al, 2000; Interviews). These services include post-acute rehabilitation, case management, and brain injury-specific community programming (CDC, 2014; BI Commission, 2011; Interviews). Governance and data for decision-making are also major gaps in the continuum of care for severe brain injury in MA (Interviews; NASHIA, 2005). The last two decades saw a surge in interest in the brain, with advances in neuroscience, diagnosis and measurement of brain injury, rehabilitation services, and brain theory (Boyle, 2001). Severe brain injury however is the new "hidden epidemic" in our society. For many, an injury to the brain is not a short-term event that can be "cured" but the beginning of a life-long disability (CDC, 2014; Langlois et al, 2006). Fortunately, even after a severe brain injury, when the right rehabilitation is provided at the right time, the "rest of life" journey can be a positive one for many (Marquez de la Plata, 2015; Langlois et al, 2006). Severe brain injury can lead to a "new normal" as patients regain skills, find new meaning and in life, and take on new family, volunteer, and work roles. Throughout this brief, the term "severe brain injury" refers to "severe acquired brain injury," or any injury to the brain that occurs after birth. This definition does not include

  7. Strauss (1969) revisited: a psychosis continuum in the general population?

    Science.gov (United States)

    van Os, J; Hanssen, M; Bijl, R V; Ravelli, A

    2000-09-29

    . Psychiatry 21, 581-586) that dichotomously diagnosed psychotic symptoms in clinical samples are, in fact, part of a continuum of experiences, may also apply to the general population. The boundaries of the psychosis phenotype may extend beyond the clinical concept of schizophrenia.

  8. Estimating forest conversion rates with annual forest inventory data

    Science.gov (United States)

    Paul C. Van Deusen; Francis A. Roesch

    2009-01-01

    The rate of land-use conversion from forest to nonforest or natural forest to forest plantation is of interest for forest certification purposes and also as part of the process of assessing forest sustainability. Conversion rates can be estimated from remeasured inventory plots in general, but the emphasis here is on annual inventory data. A new estimator is proposed...

  9. 78 FR 18307 - Forest Service

    Science.gov (United States)

    2013-03-26

    ... Forest Service Forest Resource Coordinating Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting; Correction. SUMMARY: The Forest Service published a document in the Federal Register of January 31, 2013, concering a notice of meeting for the Forest Resource Coordinating Committee. The document...

  10. 78 FR 13621 - Forest Service

    Science.gov (United States)

    2013-02-28

    ... Forest Service San Bernardino National Forest; California; Omya Sentinel and Butterfield Quarry Expansion Project AGENCY: Forest Service, USDA. ACTION: Notice of intent to prepare an environmental impact.... Department of Agriculture, Forest Service, San Bernardino National Forest (SBNF); and A Mining and Land...

  11. Forest report 2016; Waldzustandsbericht 2016

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2016-07-01

    This forest condition report of Hesse (Germany) includes the following topics: forest condition survey for all tree species, forest in the in the Rhine-Main area, weather and climate, soil water balance and drought stress, insects and fungi, Forestry Environment Monitoring, infiltrated substances, main results of Forest soil survey in Hesse (BZE II), the substrate group red sandstone, heavy metal contamination of forests.

  12. On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI

    Science.gov (United States)

    Heinzel, P.; Kleint, L.; Kašparová, J.; Krucker, S.

    2017-09-01

    The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory has provided unique observations of off-limb flare emission. White-light continuum enhancements were detected in the “continuum” channel of the Fe 6173 Å line during the impulsive phase of the observed flares. In this paper we aim to determine which radiation mechanism is responsible for such enhancement being seen above the limb, at chromospheric heights around or below 1000 km. Using a simple analytical approach, we compare two candidate mechanisms, the hydrogen recombination continuum (Paschen) and the Thomson continuum due to scattering of disk radiation on flare electrons. Both mechanisms depend on the electron density, which is typically enhanced during the impulsive phase of a flare as the result of collisional ionization (both thermal and also non-thermal due to electron beams). We conclude that for electron densities higher than 1012 cm-3, the Paschen recombination continuum significantly dominates the Thomson scattering continuum and there is some contribution from the hydrogen free-free emission. This is further supported by detailed radiation-hydrodynamical (RHD) simulations of the flare chromosphere heated by the electron beams. We use the RHD code FLARIX to compute the temporal evolution of the flare-heating in a semi-circular loop. The synthesized continuum structure above the limb resembles the off-limb flare structures detected by HMI, namely their height above the limb, as well as the radiation intensity. These results are consistent with recent findings related to hydrogen Balmer continuum enhancements, which were clearly detected in disk flares by the IRIS near-ultraviolet spectrometer.

  13. The significance of turbulent flow representation in single-continuum models

    Science.gov (United States)

    Reimann, T.; Rehrl, C.; Shoemaker, W.B.; Geyer, T.; Birk, S.

    2011-01-01

    Karst aquifers exhibit highly conductive features caused from rock dissolution processes. Flow within these structures can become turbulent and therefore can be expressed by nonlinear gradient functions. One way to account for these effects is by coupling a continuum model with a conduit network. Alternatively, turbulent flow can be considered by adapting the hydraulic conductivity within the continuum model. Consequently, the significance of turbulent flow on the dynamic behavior of karst springs is investigated by an enhanced single-continuum model that results in conduit-type flow in continuum cells (CTFC). The single-continuum approach CTFC represents laminar and turbulent flow as well as more complex hybrid models that require additional programming and numerical efforts. A parameter study is conducted to investigate the effects of turbulent flow on the response of karst springs to recharge events using the new CTFC approach, existing hybrid models, and MODFLOW-2005. Results reflect the importance of representing (1) turbulent flow in karst conduits and (2) the exchange between conduits and continuum cells. More specifically, laminar models overestimate maximum spring discharge and underestimate hydraulic gradients within the conduit. It follows that aquifer properties inferred from spring hydrographs are potentially impaired by ignoring flow effects due to turbulence. The exchange factor used for hybrid models is necessary to account for the scale dependency between hydraulic properties of the matrix continuum and conduits. This functionality, which is not included in CTFC, can be mimicked by appropriate use of the Horizontal Flow Barrier package for MODFLOW. Copyright 2011 by the American Geophysical Union.

  14. Forest, trees and agroforestry

    DEFF Research Database (Denmark)

    Rahman, Syed Ajijur; Foli, Samson; Al Pavel, Muha Abdullah

    2015-01-01

    Scientific community is concerned to address contemporary issues of food production and conserve tropical forests that support the livelihoods of millions of people. A review of the literature on deforestation, forest utilization, and landscape management for ecosystem services was conducted...... to investigate the effect on peoples’ livelihoods and the sustainability of forests in Bangladesh as a case. Results reveal that the current rate of deforestation is at 0.3% per annum meaning that, with current trends, in two decades little or no forest cover will exist in Bangladesh making the livelihoods...... of millions of people who depend on forest resources extremely vulnerable. We ask; can better implementation of forest policies and landscape management contribute to curb the current level of deforestation? Agroforestry systems in particular are a promising strategy to sustainably deliver food, nutritional...

  15. Forests beyond income

    DEFF Research Database (Denmark)

    Walelign, Solomon Zena

    2013-01-01

    Since the last few decades, there is an increasing recognition of the contribution of forest and environmental resources to rural poverty. Using data from two rural villages in Mozambique, this study aimed to assess the contribution of forest and environmental resources to rural poverty incidence......, depth and severity on the one hand, and the dependency of rural poor and non-poor households on forest and environmental resources on the other. The three variants of the FGT poverty index, with and without forest and environmental income, and the relative shares of each livelihood activities......-poor sample households respectively. With regard to the contribution of forest and environmental resources to rural poverty, dramatic increase in the incidence, depth and severity of poverty were observed when forest and environmental income was excluded from sample households' total income accounting...

  16. Does participatory forest management promote sustainable forest utilisation in Tanzania?

    DEFF Research Database (Denmark)

    Treue, Thorsten; Ngaga, Y.M.; Meilby, Henrik

    2014-01-01

    Over the past 20 years, Participatory Forest Management (PFM) has become a dominant forest management strategy in Tanzania, covering more than 4.1 million hectares. Sustainable forest use and supply of wood products to local people are major aims of PFM. This paper assesses the sustainability...... of forest utilisation under PFM, using estimates of forest condition and extraction rates based on forest inventories and 480 household surveys from 12 forests; seven under Community Based Forest Management (CBFM), three under Joint Forest Management (JFM) and two under government management (non......-PFM). Extraction of products is intense in forests close to Dar es Salaam, regardless of management regime. Further from Dar es Salaam, harvesting levels in forests under PFM are, with one prominent exception, broadly sustainable. Using GIS data from 116 wards, it is shown that half of the PFM forests in Tanzania...

  17. Kentucky's forests, 2004

    Science.gov (United States)

    Jeffery A. Turner; Christopher M. Oswalt; James L. Chamberlain; Roger C. Conner; Tony G. Johnson; Sonja N. Oswalt; KaDonna C. Randolph

    2008-01-01

    Forest land area in the Commonwealth of Kentucky amounted to 11.97 million acres, including 11.6 million acres of timberland. Over 110 different species, mostly hardwoods, account for an estimated 21.2 billion cubic feet of all live tree volume. Hardwood forest types occupy 85 percent of Kentucky’s timberland, and oak-hickory is the dominant forest-type group...

  18. Forest water contamination

    Science.gov (United States)

    Roger M. Rowell

    2006-01-01

    Forests play a key role in cleaning water. Precipitation is “'filtered” through the tree canopy and filtered again throuph the organic matter on the forest floor. The water then seeps into the subsurface to replenish the ground water. Approximately 80% of the freshwater in the United States originates in the 650 million acres (265 million hectares) of forest that...

  19. Communicating forest sector sustainability

    OpenAIRE

    Korhonen, E.; Toppinen, Anne; Lähtinen, K.; Ranacher, L.; Werner, Andrea; Stern, Tobias; Kutnar, Andreja

    2016-01-01

    Communication is an important tool in maintaining legitimacy and acceptability of forest sector operations and activities, and expectations by the general public on the forest sector conduct in Europe are in general very high. Despite this, there is scarce research in crossnational context on how forest sector sustainability is communicated to the general public, and what development areas can be identified in terms of communication content. This study applies a qualitative content analysis i...

  20. Pennsylvania forests 2014

    Science.gov (United States)

    Thomas A. Albright; William H. McWilliams; Richard H. Widmann; Brett J. Butler; Susan J. Crocker; Cassandra M. Kurtz; Shawn Lehman; Tonya W. Lister; Patrick D. Miles; Randall S. Morin; Rachel Riemann; James E. Smith

    2017-01-01

    This report summarizes the third cycle of annualized inventory of Pennsylvania with field data collected from 2009 through 2014. Pennsylvania has 16.9 million acres of forest land dominated by sawtimber stands of oak/hickory and maple/beech/birch forest-type groups. Volumes continue to increase as the forests age with an average of 2,244 cubic feet per acre on...

  1. Protecting forests through partnerships

    OpenAIRE

    Widman, Ulrika

    2016-01-01

    This thesis addresses the potential of private-public partnerships (PPPs) to involve private forest owners in formal forest protection. These partnerships have been widely advocated as means to engage actors from diverse sectors in collaborative new relationships, formed in a step-wise manner, to improve management of resources that combine public and private goods. Nature Conservation Agreements (NCAs) are the first kind of PPPs to be used in Swedish forest protection. NCAs were introduced i...

  2. Francis Marion National Forest forest plan revision - ecosystems & restoration needs

    Science.gov (United States)

    Mark Danaher

    2016-01-01

    The Forest Service is currently revising the previous 1995 Forest Plan for the Francis Marion National Forest in Coastal South Carolina developed in the wake of Hurricane Hugo which devastated the forest in 1989. Since 1995, the human communities surrounding the Francis Marion National Forest have grown and changed significantly. The revised Francis Marion Forest Plan...

  3. Lyman continuum leaking galaxies. Search strategies and local candidates

    Science.gov (United States)

    Bergvall, N.; Leitet, E.; Zackrisson, E.; Marquart, T.

    2013-06-01

    Context. Star-forming dwarf galaxies may have played an important role in the reionization of the Universe, provided that some fraction of their ionizing radiation were able to escape into the intergalactic medium. Local galaxies exhibiting such Lyman-continuum (LyC) leakage could potentially shed light on the escape mechanisms involved, but only two low-redshift cases of LyC leakage have been identified so far. Here, we argue that this meager harvest may be caused by unsuitable selection criteria. Candidates for LyC leakage are normally selected by indicators of starburst activity, one of which is a high equivalent width in Hα. Such a criterion will guarantee a high production of LyC photons but will also bias the selection in favour of a high column density in the neutral gas, effectively ruling out LyC escape. Aims: In this work we want to investigate whether the lack of local LyC emitters can be caused in part by biased selection criteria, and we present a novel method of selecting targets with high escape fractions. By applying these criteria, we assemble a sample of observation targets to study their basic properties. Methods: We introduce a new selection strategy here where the potential LyC leakers are selected by their blue colours and weak emission lines. The selection is based on data from the Sloan Digital Sky Survey (SDSS). We also take a closer look at the properties of 8 LyC leaking candidates at z ~ 0.03 which we have observed with ESO/NTT in broadband B and Hα. Results: We find that 7 of the 8 target galaxies are involved in interaction with neighbours or show signs of mergers. In 7 cases the young stellar population is clearly displaced relative to the main body of these galaxies, often directly bordering the halo region. In about half of our targets the absorption spectra show young post-starburst signatures. Comparing the scale lengths in Hα with those of the stellar continua shows that the scale lengths in Hα typically are 30% smaller

  4. Forest structure in low diversity tropical forests: a study of Hawaiian wet and dry forests

    Science.gov (United States)

    R. Ostertag; F. Inman-Narahari; S. Cordell; C.P. Giardina; L. Sack

    2014-01-01

    The potential influence of diversity on ecosystem structure and function remains a topic of significant debate, especially for tropical forests where diversity can range widely. We used Center for Tropical Forest Science (CTFS) methodology to establish forest dynamics plots in montane wet forest and lowland dry forest on Hawai‘i Island. We compared the species...

  5. Wisconsin's fourth forest inventory: area.

    Science.gov (United States)

    W. Brad Smith

    1986-01-01

    In 1983, the fourth Wisconsin forest inventory found 14.8 million acres of commercial forest land, an increase of nearly 2% since 1968. This bulletin analyzes findings from the inventory and presents detailed tables of forest area.

  6. Nebraska's forest resources in 2003

    Science.gov (United States)

    W. Keith Moser; Gary J. Brand; Mark H. Hansen; William R. Lovett

    2005-01-01

    Reports results of the first three yearly panels (2001-2003) of the fourth inventory of Nebraska's forest resources. Includes information on forest area; volume; biomass; growth, removals, and mortality; and forest health.

  7. Coupling Strategies Investigation of Hybrid Atomistic-Continuum Method Based on State Variable Coupling

    Directory of Open Access Journals (Sweden)

    Qian Wang

    2017-01-01

    Full Text Available Different configurations of coupling strategies influence greatly the accuracy and convergence of the simulation results in the hybrid atomistic-continuum method. This study aims to quantitatively investigate this effect and offer the guidance on how to choose the proper configuration of coupling strategies in the hybrid atomistic-continuum method. We first propose a hybrid molecular dynamics- (MD- continuum solver in LAMMPS and OpenFOAM that exchanges state variables between the atomistic region and the continuum region and evaluate different configurations of coupling strategies using the sudden start Couette flow, aiming to find the preferable configuration that delivers better accuracy and efficiency. The major findings are as follows: (1 the C→A region plays the most important role in the overlap region and the “4-layer-1” combination achieves the best precision with a fixed width of the overlap region; (2 the data exchanging operation only needs a few sampling points closer to the occasions of interactions and decreasing the coupling exchange operations can reduce the computational load with acceptable errors; (3 the nonperiodic boundary force model with a smoothing parameter of 0.1 and a finer parameter of 20 can not only achieve the minimum disturbance near the MD-continuum interface but also keep the simulation precision.

  8. Estimation of tomato leaf nitrogen content using continuum-removal spectroscopy analysis technique

    Science.gov (United States)

    Ding, Yongjun; Li, Minzan; Zheng, Lihua; Sun, Hong

    2012-11-01

    In quantitative analysis of spectral data, noises and background interference always degrades the accuracy of spectral feature extraction. Continuum-removal analysis enables the isolation of absorption features of interest, thus increasing the coefficients of determination and facilitating the identification of more sensible absorption features. The purpose of this study was to test continuum-removal methodology with Visual-NIR spectral data of tomato leaf. Through analyzing the correlation between continuum-removal spectrum and nitrogen content, 15 characteristics parameters reflected changing tendency of nitrogen content were chosen, which is at 335, 405, 500, 520, 540, 550, 560, 580, 620, 640, 683, 704, 720, 736 and 770 nm. Finally, the variance inflation analysis and stepwise regression method was used to develop the prediction model of the nitrogen content of tomato leaf. The result showed that the predicted model, which used the values of continuum-removal spectrum at 335 and 720nm as input variables, had high predictive ability, with R2 of 0.755. The root mean square errors of prediction using a leave-one-out cross validation method were 0.513. These results suggest that the continuum-removal spectroscopy analysis has better potential to diagnose tomato growth in greenhouse.

  9. Pairing in the BCS and LN approximations using continuum single particle level density

    Energy Technology Data Exchange (ETDEWEB)

    Id Betan, R.M., E-mail: idbetan@ifir-conicet.gov.ar [Instituto de Física Rosario (CONICET-UNR), Bv. 27 de Febrero 210 bis, S2000EZP Rosario (Argentina); Facultad de Ciencias Exactas, Ingeniería y Agrimensura (UNR), Av. Pellegrini 250, S2000BTP Rosario (Argentina); Instituto de Estudios Nucleares y Radiaciones Ionizantes (UNR), Riobamba y Berutti, S2000EKA Rosario (Argentina); Repetto, C.E. [Instituto de Física Rosario (CONICET-UNR), Bv. 27 de Febrero 210 bis, S2000EZP Rosario (Argentina); Facultad de Ciencias Exactas, Ingeniería y Agrimensura (UNR), Av. Pellegrini 250, S2000BTP Rosario (Argentina)

    2017-04-15

    Understanding the properties of drip line nuclei requires to take into account the correlations with the continuum spectrum of energy of the system. This paper has the purpose to show that the continuum single particle level density is a convenient way to consider the pairing correlation in the continuum. Isospin mean-field and isospin pairing strength are used to find the Bardeen–Cooper–Schrieffer (BCS) and Lipkin–Nogami (LN) approximate solutions of the pairing Hamiltonian. Several physical properties of the whole chain of the Tin isotope, as gap parameter, Fermi level, binding energy, and one- and two-neutron separation energies, were calculated and compared with other methods and with experimental data when they exist. It is shown that the use of the continuum single particle level density is an economical way to include explicitly the correlations with the continuum spectrum of energy in large scale mass calculation. It is also shown that the computed properties are in good agreement with experimental data and with more sophisticated treatment of the pairing interaction.

  10. Nonlinear modeling of crystal system transition of black phosphorus using continuum-DFT model.

    Science.gov (United States)

    Setoodeh, AliReza; Farahmand, Hamed

    2017-11-13

    In this paper, nonlinear behavior of black phosphorus crystals is investigated in tandem with dispersion corrected density functional theory (DFT-D) analysis under uniaxial loading. According to the distinguished anisotropic behavior of black phosphorus due to its morphological anisotropy, a hyperelastic anisotropic (HA) model named continuum-DFT is established to predict nonlinear behavior of the material. In this respect, uniaxial tensile Cauchy stresses are employed on both the DFT-D and HA models along zig-zag direction. Simultaneously, the transition of crystal system is recognized in about 4.5 GPa of the applied uniaxial tensile stress on the DFT-D simulation in the nonlinear region. In order to develop the nonlinear continuum model, unknown constants are surveyed with optimized least square technique. In this regard, the continuum model is obtained to reproduce the Cauchy stress-stretch and density of strain energy-stretch results of the DFT-D simulation. Consequently, the modified HA model is introduced to characterize the nonlinear behavior of black phosphorus. More importantly, the specific transition of crystal system is successfully predicted in the new modified continuum-DFT model. The results reveal that the modified continuum model is well defined to replicate the nonlinear behavior of black phosphorus. © 2017 IOP Publishing Ltd.

  11. Applications of Artificial Neural Networks in Structural Engineering with Emphasis on Continuum Models

    Science.gov (United States)

    Kapania, Rakesh K.; Liu, Youhua

    1998-01-01

    The use of continuum models for the analysis of discrete built-up complex aerospace structures is an attractive idea especially at the conceptual and preliminary design stages. But the diversity of available continuum models and hard-to-use qualities of these models have prevented them from finding wide applications. In this regard, Artificial Neural Networks (ANN or NN) may have a great potential as these networks are universal approximators that can realize any continuous mapping, and can provide general mechanisms for building models from data whose input-output relationship can be highly nonlinear. The ultimate aim of the present work is to be able to build high fidelity continuum models for complex aerospace structures using the ANN. As a first step, the concepts and features of ANN are familiarized through the MATLAB NN Toolbox by simulating some representative mapping examples, including some problems in structural engineering. Then some further aspects and lessons learned about the NN training are discussed, including the performances of Feed-Forward and Radial Basis Function NN when dealing with noise-polluted data and the technique of cross-validation. Finally, as an example of using NN in continuum models, a lattice structure with repeating cells is represented by a continuum beam whose properties are provided by neural networks.

  12. The quantitative genetic architecture of the bold-shy continuum in zebrafish, Danio rerio.

    Directory of Open Access Journals (Sweden)

    Mary E Oswald

    Full Text Available In studies of consistent individual differences (personality along the bold-shy continuum, a pattern of behavioral correlations frequently emerges: individuals towards the bold end of the continuum are more likely to utilize risky habitat, approach potential predators, and feed under risky conditions. Here, we address the hypothesis that observed phenotypic correlations among component behaviors of the bold-shy continuum are a result of underlying genetic correlations (quantitative genetic architecture. We used a replicated three-generation pedigree of zebrafish (Danio rerio to study three putative components of the bold-shy continuum: horizontal position, swim level, and feeding latency. We detected significant narrow-sense heritabilities as well as significant genetic and phenotypic correlations among all three behaviors, such that fish selected for swimming at the front of the tank swam closer to the observer, swam higher in the water column, and fed more quickly than fish selected for swimming at the back of the tank. Further, the lines varied in their initial open field behavior (swim level and activity level. The quantitative genetic architecture of the bold-shy continuum indicates that the multivariate behavioral phenotype characteristic of a "bold" personality type may be a result of correlated evolution via underlying genetic correlations.

  13. Managing the world's forests.

    Science.gov (United States)

    Sharma, N; Rowe, R

    1992-06-01

    Forests play a vital role in balancing natural systems: the stabilization of global climate and the management of water and land. 30% of the earth's total land area is forested. 66% of the tropical moist forests are in Latin America and the remainder in Africa and Asia. 75% of tropical dry forests are in Africa. Temperate forests are primarily in developed countries. Deforestation and misuse of forests occurs primarily in developing countries at significant social, economic, and environmental costs. Losses have occurred in fuelwood, fodder, timber, forest products, biological diversity, habitats, genetic materials for food and medicine. The World Bank's evolving role in forestry is briefly described. Agreement has not been reached among people or nations about the most appropriate means to balance conservation and development goals. The challenge is to stabilize existing forests and increase forest planting. The causes of forest degradation must be understood. Direct causes include agricultural encroachment, cattle ranching, fuelwood gathering, commercial logging, and infrastructure development. These direct causes are driven by economic, social, and political forces: market and policy failures, population growth, and poverty. The market failures include: 1) the lack of clearly defined property rights on forest resources for now and the future, 2) the conflict between individual and societal needs, 3) the difficulty in placing a value on nonmarket environmental services and joint products, and 4) the separation between private and social costs. The solution is action at the local, national, and global levels. Countries must establish forest policy. The existing government incentives which promote deforestation must be changed. For example, concession policy and royalty systems must be corrected; explicit and implicit export subsidies on timber and forest products must be stopped. Private incentives must be established to promote planting of trees, practicing

  14. Coarse-to-Fine Segmentation with Shape-Tailored Continuum Scale Spaces

    KAUST Repository

    Khan, Naeemullah

    2017-11-09

    We formulate an energy for segmentation that is designed to have preference for segmenting the coarse over fine structure of the image, without smoothing across boundaries of regions. The energy is formulated by integrating a continuum of scales from a scale space computed from the heat equation within regions. We show that the energy can be optimized without computing a continuum of scales, but instead from a single scale. This makes the method computationally efficient in comparison to energies using a discrete set of scales. We apply our method to texture and motion segmentation. Experiments on benchmark datasets show that a continuum of scales leads to better segmentation accuracy over discrete scales and other competing methods.

  15. Motion Compensation of Tendon-Sheath Driven Continuum Manipulator for Endoscopic Surgery

    Directory of Open Access Journals (Sweden)

    Lau K. C.

    2015-01-01

    Full Text Available Tendon-sheath actuation mechanism is widely used in surgical robot, especially in endoscopic surgery, due to its capable of providing remote force and action transmission through long and flexible channel. However, hysteresis, backlash, nonlinear friction are the drawbacks of this mechanism. Our surgical robot use continuum manipulator which is useful in endoscopic surgery, due to its flexible and simple structure. Unlike other literatures that focus on tendon-sheath compensation only, the continuum manipulator is also taken into application level analysis. A model based feedforward motion compensation for tendon-sheath driven continuum manipulator is presented. The model is validated by using optical tracking system to trace the distal end position. Experiment result shows that the proposed model reduces the position error less than 5%.

  16. Progress toward bridging from atomistic to continuum modeling to predict nuclear waste glass dissolution.

    Energy Technology Data Exchange (ETDEWEB)

    Zapol, Peter (Argonne National Laboratory, Argonne, IL); Bourg, Ian (Lawrence Berkeley National Laboratories, Berkeley, CA); Criscenti, Louise Jacqueline; Steefel, Carl I. (Lawrence Berkeley National Laboratories, Berkeley, CA); Schultz, Peter Andrew

    2011-10-01

    This report summarizes research performed for the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Subcontinuum and Upscaling Task. The work conducted focused on developing a roadmap to include molecular scale, mechanistic information in continuum-scale models of nuclear waste glass dissolution. This information is derived from molecular-scale modeling efforts that are validated through comparison with experimental data. In addition to developing a master plan to incorporate a subcontinuum mechanistic understanding of glass dissolution into continuum models, methods were developed to generate constitutive dissolution rate expressions from quantum calculations, force field models were selected to generate multicomponent glass structures and gel layers, classical molecular modeling was used to study diffusion through nanopores analogous to those in the interfacial gel layer, and a micro-continuum model (K{mu}C) was developed to study coupled diffusion and reaction at the glass-gel-solution interface.

  17. Numerical Study on Couette Flow in Nanostructured Channel using Molecular-continuum Hybrid Method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Youngjin; Jeong, Myunggeun; Ha, Man Yeong [Pusan Nat’l Univ., Busan (Korea, Republic of)

    2017-06-15

    A molecular-continuum hybrid method was developed to simulate microscale and nanoscale fluids where continuum fluidic cannot be used to predict Couette flow. Molecular dynamics simulation is used near the solid surface where the flow cannot be predicted by continuum fluidic, and Navier-Stokes equations are used in the other regions. Numerical simulation of Couette flow was performed using the hybrid method to investigate the effect of solid-liquid interaction and surface roughness in a nanochannel. It was found that the solid-liquid interaction and surface roughness influence the boundary condition. When the surface energy is low, slippage occurs near the solid surface, and the magnitude of slippage decreases with increase in surface energy. When the surface energy is high, a locking boundary condition is formed. The roughness disturbs slippage near the solid surface and promotes the locking boundary condition.

  18. On the influence of pseudoelastic material behaviour in planar shape-memory tubular continuum structures

    Science.gov (United States)

    Greiner-Petter, Christoph; Sattel, Thomas

    2017-12-01

    For planar tubular continuum structures based on precurved shape memory alloy tubes a beam model with respect to the pseudoelastic material behaviour of NiTi is derived. Thereunto a constitutive material law respecting tension-compression asymmetry as well as hysteresis is used. The beam model is then employed to calculate equilibrium curvatures of concentric tube assemblies without clearance between the tubes. In a second step, the influence of clearance is approximated to account for non-concentric tube assemblies. These elastokinematic results are integrated into a purely kinematic model to describe the cannula path under the presence of material hysteresis and clearance. Finally a photogrammetric measurement system is used to track the path of an exemplary two-tube continuum structure to examine the accuracy of the proposed model. It is shown that material hysteresis leads to a hysteresis phenomena in the path of the tubular continuum structure.

  19. A morphing strategy to couple non-local to local continuum mechanics

    KAUST Repository

    Lubineau, Gilles

    2012-06-01

    A method for coupling non-local continuum models with long-range central forces to local continuum models is proposed. First, a single unified model that encompasses both local and non-local continuum representations is introduced. This model can be purely non-local, purely local or a hybrid depending on the constitutive parameters. Then, the coupling between the non-local and local descriptions is performed through a transition (morphing) affecting only the constitutive parameters. An important feature is the definition of the morphing functions, which relies on energy equivalence. This approach is useful in large-scale modeling of materials that exhibit strong non-local effects. The computational cost can be reduced while maintaining a reasonable level of accuracy. Efficiency, robustness and basic properties of the approach are discussed using one- and two-dimensional examples. © 2012 Elsevier Ltd.

  20. Accommodating state shifts within the conceptual framework of the wetland continuum

    Science.gov (United States)

    Mushet, David M.; McKenna, Owen; LaBaugh, James W.; Euliss, Ned H.; Rosenberry, Donald O.

    2018-01-01

    The Wetland Continuum is a conceptual framework that facilitates the interpretation of biological studies of wetland ecosystems. Recently summarized evidence documenting how a multi-decadal wet period has influenced aspects of wetland, lake and stream systems in the southern prairie-pothole region of North America has revealed the potential for wetlands to shift among alternate states. We propose that incorporation of state shifts into the Wetland Continuum, as originally proposed or as modified by Hayashi et al., is a relatively simple matter if one allows for shifts of wetlands along the horizontal, groundwater axis of the framework under conditions of extreme and sustained wet or dry conditions. We suggest that the ease by which state shifts can be accommodated within both the original and modified frameworks of the Wetland Continuum is a testament to the robustness of the concept when it is related to the alternative-stable-state concept.

  1. Terminology Evolution and Translation: Specificity of Referent & User’s Epistemic Continuum Exemplified in Islamic Terms

    Directory of Open Access Journals (Sweden)

    Omar A. S. Al-Shabab

    2016-01-01

    Full Text Available In the dynamics of environmental context, the referent of a linguistic sign changes, but the sign persists as a verbal symbol. Since a technical term strictly evokes one referent, it may lack in specificity due to the ever-changing reality, resulting in homonymy, overlap, and a semantic continuum based on designating by necessity. In addition to the elements of reference theory, the criteria for technical terms postulate the user, whose authority and responsibility are necessary for the term to function as a specific designator. The centrality of the user, translator or otherwise, has hermeneutic and linguistic implications for the evolution of terminology, because it stipulates that terminological meaning and usage are dependent on the user’s conscious knowledge, a condition that leads to the recognition of a user epistemic continuum parallel to the semantic necessity continuum. Ideally, a term should be universally specific in reference, and its user should be epistemologically empowered and ethically responsible.

  2. Randomly-fluctuating heterogeneous continuum model of a ballasted railway track

    Science.gov (United States)

    de Abreu Corrêa, Lucio; Quezada, Juan Carlos; Cottereau, Régis; d'Aguiar, Sofia Costa; Voivret, Charles

    2017-11-01

    This paper proposes a description of a granular medium as a stochastic heterogeneous continuum medium. The heterogeneity of the material properties field recreates the heterogeneous stress field in a granular medium. The stochastic approach means that only statistical information, easily available, is required to construct the model. The heterogeneous continuum model is Calibrated with respect to discrete simulations of a set of railway ballast samples. As they are continuum-based, the equilibrium equations can be solved on a large scale using a parallel implementation of an explicit time discretization scheme for the Finite Element Method. Simulations representative of the influence on the environment of the passage of a train on a ballasted railway track clearly show the influence of the heterogeneity. These simulations seem to correlate well with previously unexplained overly damped measurements in the free field.

  3. Towards a physics on fractals: Differential vector calculus in three-dimensional continuum with fractal metric

    Science.gov (United States)

    Balankin, Alexander S.; Bory-Reyes, Juan; Shapiro, Michael

    2016-02-01

    One way to deal with physical problems on nowhere differentiable fractals is the mapping of these problems into the corresponding problems for continuum with a proper fractal metric. On this way different definitions of the fractal metric were suggested to account for the essential fractal features. In this work we develop the metric differential vector calculus in a three-dimensional continuum with a non-Euclidean metric. The metric differential forms and Laplacian are introduced, fundamental identities for metric differential operators are established and integral theorems are proved by employing the metric version of the quaternionic analysis for the Moisil-Teodoresco operator, which has been introduced and partially developed in this paper. The relations between the metric and conventional operators are revealed. It should be emphasized that the metric vector calculus developed in this work provides a comprehensive mathematical formalism for the continuum with any suitable definition of fractal metric. This offers a novel tool to study physics on fractals.

  4. Ghana's high forests

    NARCIS (Netherlands)

    Oduro, K.A.

    2016-01-01

    Deforestation and forest degradation in the tropics have been receiving both scientific and political attention in recent decades due to its impacts on the environment and on human livelihoods. In Ghana, the continuous decline of forest resources and the high demand for timber have raised

  5. Why 'a forest conscienceness'?

    Science.gov (United States)

    M. Calver; H. Bigler-Cole; G. Bolton; J. Dargavel; A. Gaynor; P. Horwitz; J. Mills; G. Wardell-Johnson

    2005-01-01

    The phrase 'a forest conscienceness' was used in a major statement made by Charles Lane Poole, Western Australia's Conservator of Forests from 1916-1921, for the 1920 British Empire Forestry Conference. It is both relevant and contemporary at the beginning of the 21st century. We chose it as the conference theme to encourage engagement with both a...

  6. Trees for future forests

    DEFF Research Database (Denmark)

    Lobo, Albin

    Climate change creates new challenges in forest management. The increase in temperature may in the long run be beneficial for the forests in the northern latitudes, but the high rate at which climate change is predicted to proceed will make adaptation difficult because trees are long living sessi...

  7. Why sustain oak forests?

    Science.gov (United States)

    David Wm. Smith

    2006-01-01

    A brief overview and some personal thoughts are offered that deal with the implications of our social and political systems on the long-term sustainability of our forest resources. The connection of the most recent climatic events, in a geologic-time context, to the development of present day oak dominated forests of the Eastern United States is discussed. The impacts...

  8. Status of Forest Certification

    Science.gov (United States)

    Omar Espinoza; Urs Buehlmann; Michael Dockry

    2013-01-01

    Forest certification systems are voluntary, market-based initiatives to promote the sustainable use of forests. These standards assume that consumers prefer products made from materials grown in an environmentally sustainable fashion, and this in turn creates incentives for companies to adopt responsible environmental practices. One of the major reasons for the...

  9. Forests and water

    Science.gov (United States)

    Graeme Lockaby; Chelsea Nagy; James M. Vose; Chelcy R. Ford; Ge Sun; Steve McNulty; Pete Caldwell; Erika Cohen; Jennifer Moore Myers

    2013-01-01

    Key FindingsForest conversion to agriculture or urban use consistently causes increased discharge, peak flow, and velocity of streams. Subregional differences in hydrologic responses to urbanization are substantial.Sediment, water chemistry indices, pathogens, and other substances often become more concentrated after forest...

  10. Traditional Forest Management

    African Journals Online (AJOL)

    2007-03-02

    Mar 2, 2007 ... conservation programs and projects. Local communities, therefore, are the primary stewards of forest . resources. These resources are usually characterized by the local communities' culture . and management systems, where cultures are materially and spiritually built upon the physical world of the forests.

  11. Modelling in forest management

    Science.gov (United States)

    Mark J. Twery

    2004-01-01

    Forest management has traditionally been considered management of trees for timber. It really includes vegetation management and land management and people management as multiple objectives. As such, forest management is intimately linked with other topics in this volume, most especially those chapters on ecological modelling and human dimensions. The key to...

  12. Northern forests, Chapter 7

    Science.gov (United States)

    L.H. Pardo; C.L. Goodale; E.A. Lilleskov; L.H. Geiser

    2011-01-01

    The Northern Forests ecological region spans much of Canada, from Saskatchewan to Newfoundland; its southern portion extends into the northern United States (CEC 1997). The U.S. component includes the northern hardwood and spruce-fir forest types and encompasses parts of the Northeast (mountainous regions in Pennsylvania, New York, New Jersey, Connecticut,...

  13. Forest statistics for Connecticut

    Science.gov (United States)

    David R. Dickson; Teresa M. Bowers

    1976-01-01

    This report contains data from the second inventory of the forest resources of Connecticut. The inventory was completed in 1971 by the Northeastern Forest Experiment Station in cooperation with the Connecticut Department of Environmental Resources. The first inventory of Connecticut was completed in 1952. Because of many differences in standards and measurement...

  14. Cooperative Alaska Forest Inventory

    Science.gov (United States)

    Thomas Malone; Jingjing Liang; Edmond C. Packee

    2009-01-01

    The Cooperative Alaska Forest Inventory (CAFI) is a comprehensive database of boreal forest conditions and dynamics in Alaska. The CAFI consists of field-gathered information from numerous permanent sample plots distributed across interior and south-central Alaska including the Kenai Peninsula. The CAFI currently has 570 permanent sample plots on 190 sites...

  15. Forest fires in Missouri.

    Science.gov (United States)

    Donald A. Haines; William A. Main; John S. Crosby

    1973-01-01

    Describes factors that contribute to forest fires on two of the State of Missouri's Protection Districts and the Clark National Forest. Includes an analysis of fire cause, annual distribution, weather, and activity by day of week; also discusses multiple-fire day.

  16. Autonomous Forest Fire Detection

    NARCIS (Netherlands)

    Breejen, E. den; Breuers, M.; Cremer, F.; Kemp, R.A.W.; Roos, M.; Schutte, K.; Vries, J.S. de

    1998-01-01

    Forest fire detection is a very important issue in the pre-suppression process. Timely detection allows the suppression units to reach the fire in its initial stages and this will reduce the suppression costs considerably. The autonomous forest fire detection principle is based on temporal contrast

  17. Forest resources of Louisiana

    Science.gov (United States)

    James F. Rosson; William H. McWilliams; Paul D. Frey

    1988-01-01

    This report documents the findings of the fifth forest survey of Louisiana. Trend data on the forest resource are presented along with appropriate tables and figures. The appendix contains definitions of terms, a discussion of data reliability, a tree species list, and 22 standard statistical tables. Data are reported for January 1, 1984. Major highlights are listed...

  18. Forests [Chapter 7

    Science.gov (United States)

    Linda A. Joyce; Steven W. Running; David D. Breshears; Virginia H. Dale; Robert W. Malmsheimer; R. Neil Sampson; Brent Sohngen; Christopher W. Woodall

    2014-01-01

    Forests occur within urban areas, at the interface between urban and rural areas (wildland-urban interface), and in rural areas. Urban forests contribute to clean air, cooling buildings, aesthetics, and recreation in parks. Development in the wildland-urban interface is increasing because of the appeal of owning homes near or in the woods. In rural areas, market...

  19. Forest Tent Caterpillar

    Science.gov (United States)

    Harold O. Belzer; Robert C. Morris

    1978-01-01

    The forest tent caterpillar (Malacosoma disstria Hubner)3 may be found throughout the United States and Canada wherever hardwoods grow. It is a native insect that has attracted attention since colonial times. Regionwide outbreaks have occurred at intervals varying from 6 to 16 years in northern areas. Southern gum forests in southwest Alabama and southern Louisiana...

  20. Beyond the continuum: a multi-dimensional phase space for neutral-niche community assembly.

    Science.gov (United States)

    Latombe, Guillaume; Hui, Cang; McGeoch, Melodie A

    2015-12-22

    Neutral and niche processes are generally considered to interact in natural communities along a continuum, exhibiting community patterns bounded by pure neutral and pure niche processes. The continuum concept uses niche separation, an attribute of the community, to test the hypothesis that communities are bounded by pure niche or pure neutral conditions. It does not accommodate interactions via feedback between processes and the environment. By contrast, we introduce the Community Assembly Phase Space (CAPS), a multi-dimensional space that uses community processes (such as dispersal and niche selection) to define the limiting neutral and niche conditions and to test the continuum hypothesis. We compare the outputs of modelled communities in a heterogeneous landscape, assembled by pure neutral, pure niche and composite processes. Differences in patterns under different combinations of processes in CAPS reveal hidden complexity in neutral-niche community dynamics. The neutral-niche continuum only holds for strong dispersal limitation and niche separation. For weaker dispersal limitation and niche separation, neutral and niche processes amplify each other via feedback with the environment. This generates patterns that lie well beyond those predicted by a continuum. Inferences drawn from patterns about community assembly processes can therefore be misguided when based on the continuum perspective. CAPS also demonstrates the complementary information value of different patterns for inferring community processes and captures the complexity of community assembly. It provides a general tool for studying the processes structuring communities and can be applied to address a range of questions in community and metacommunity ecology. © 2015 The Author(s).

  1. The continuum model of selection in human tumors: general paradigm or niche product?

    Science.gov (United States)

    Leedham, Simon; Tomlinson, Ian

    2012-07-01

    Berger and colleagues recently proposed a continuum model of how somatic mutations cause tumors to grow, thus supplementing the established binary models, such as oncogene activation and "two hits" at tumor suppressor loci. In the basic continuum model, decreases or increases in gene function, short of full inactivation or activation, impact linearly on cancer development. An extension, called the fail-safe model, envisaged an optimum level of gene derangement for tumor growth, but proposed that the cell gained protection from tumorigenesis because additional mutations caused excessive derangement. Most of the evidence in support of the continuum model came from Pten mutant mice rather than humans. In this article, we assess the validity and applicability of the continuum and fail-safe models. We suggest that the latter is of limited use: In part, it restates the existing "just right" of optimum intermediate gene derangement in tumorigenesis, and in part it is inherently implausible that a cell should avoid becoming cancerous only when it is some way down the road to that state. In contrast, the basic continuum model is a very useful addition to the other genetic models of tumorigenesis, especially in certain scenarios. Fittingly for a quantitative model, we propose that the continuum model is most likely to apply where multiple, cancer-promoting mutations have relatively small, additive effects, either through the well-established case of additive germline predisposition alleles or in a largely hypothetical situation where cancers may have acquired several somatic "mini-driver" mutations, each with weaker effects than classical tumor suppressors or fully activated oncogenes. ©2012 AACR.

  2. Fertilization in northern forests

    DEFF Research Database (Denmark)

    Hedwall, Per Ola; Gong, Peichen; Ingerslev, Morten

    2014-01-01

    Forests of northern ecosystems respond slowly to management activities and the possibilities to increase the growth in a short-term perspective and meet swift increases in society's demand for biomass are small. An exception among the silvicultural measures is fertilization which can be applied...... in combination with present management systems and, almost instantly, enhances forest productivity. There may, however, be both economic and environmental constraints to large-scale applications of fertilizers in forest. Here we review the literature concerning biomass production of forests under different...... fertilization regimens, environmental constraints and possibilities in northern forests on mineral soils. Further on we discuss the implications of both extensive and more intensive fertilization in relation to the developing bioeconomy, which encompasses the production and conversion of renewable biological...

  3. METKA - Forest energy profitably

    Energy Technology Data Exchange (ETDEWEB)

    Kymaelaeinen, M. (FMA Kanta-Hame, Hameenlinna (Finland)); Rieppo, K. (TTS Research, Hameenlinna (Finland)), e-mail: matti.kymalainen@mhy.fi, e-mail: kaarlo.rieppo@tts.fi

    2010-07-01

    The harvesting and profitability of forest energy in Finland is practically entirely dependent on state subsidies. Currently, there is a lot to improve in forest energy knowledge and competence. METKA - Forest energy profitably project (2008-2011) aims at increasing the cost efficiency of the forest energy chain and the volume of the supply chain in Haeme region. The project ia coordinated by Forest Management Association Kanta-Haeme (Kanta-Haemeen Metsanhoitoyhdistys ry). Project partners include FMA Paeijaet-Haeme, TTS Research and the Finnish Forest Research Institute's (METLA) Joensuu unit. METKA -project belongs to the Rural Development Programme for Mainland Finland 2007-2013 and is being funded partly by the European Agricultural Fund for Rural Development (EAFRD). The final project objective is to develop a new operational forest energy model for FMA Kanta-Haeme and FMA Paeijaet-Haeme. In order to create the operational model, the project has been divided into several sub-tasks, in which TTS Research and Metla are responsible for the research. TTS Research conducts studies that focus on forest energy harvesting and processing. The studies investigate especially small-diameter energy wood harvesting. Majority of the studies investigate the use of time, and they form the basis for cost and profit analyses. Metla is responsible or areas of research that contribute to the development of a forest energy storage's moisture estimation algorithm and a forest energy harvesting yield calculation program. Upon completion, the calculation program and the estimation algorithm are integrated to the logistics control system developed by FMA Kanta-Haeme and FMA Paeijaet-Haeme and taken into use as aids in forestry planning. During 2008 and 2009, several practical tests have been performed. Tests will be executed in autumn 2010 as well. The analysis of the results is likely to be completed in 2010, and the results is likely to be completed in 2010, and the results

  4. Control of density fluctuations in atomistic-continuum simulations of dense liquids

    DEFF Research Database (Denmark)

    Kotsalis, E.M.; Walther, Jens Honore; Koumoutsakos, P.

    2007-01-01

    We present a control algorithm to eliminate spurious density fluctuations associated with the coupling of atomistic and continuum descriptions for dense liquids. A Schwartz domain decomposition algorithm is employed to couple molecular dynamics for the simulation of the atomistic system with a co......We present a control algorithm to eliminate spurious density fluctuations associated with the coupling of atomistic and continuum descriptions for dense liquids. A Schwartz domain decomposition algorithm is employed to couple molecular dynamics for the simulation of the atomistic system...

  5. Molecular response functions for the polarizable continuum model physical basis and quantum mechanical formalism

    CERN Document Server

    Cammi, Roberto

    2013-01-01

    This Brief presents the main aspects of the response functions theory (RFT) for molecular solutes described within the framework of the Polarizable Continuum Model (PCM). PCM is a solvation model for a Quantum Mechanical molecular system in which the solvent is represented as a continuum distribution of matter. Particular attention is devoted to the description of the basic features of the PCM model, and to the problems characterizing the study of the response function theory for molecules in solution with respect to the analogous theory on isolated molecules.

  6. Static third-harmonic lines in widely variable fiber continuum generation

    Science.gov (United States)

    Tu, Haohua; Zhao, Youbo; Liu, Yuan; Boppart, Stephen A.

    2014-01-01

    An intriguing phenomenon of third-harmonic generation under fiber continuum generation is the emission of an anharmonic signal. One popular interpretation of this effect has developed into a general theory of fiber third-harmonic generation. Here we produce "static" third-harmonic lines dictated fully by fiber properties independent of pump parameters, in contrast to the signals of all known phase-matched nonlinear optical processes that vary dynamically with these parameters. We argue that the anharmonic signal is an illusion of the continuum generation, that it is in fact harmonic, and that this theory should be reevaluated.

  7. Strategic health communication across the continuum of breast cancer care in limited-resource countries.

    Science.gov (United States)

    Kreps, Gary L; Sivaram, Rama

    2008-10-15

    Strategic health communication is a critical component of healthcare that should be implemented across the continuum of care. Recognizing the importance of communication strategies and incorporating such strategies into healthcare policies, programs, and interventions is essential to the effective delivery of breast cancer care. The authors reviewed relevant literature and suggested practical evidence-based strategies for effective communication interventions across the continuum of care for breast cancer patients, including early detection, diagnosis, treatment, survivorship, palliative care, and end-of-life care. Examples were provided from limited-resource nations to support health communication recommendations. (c) 2008 American Cancer Society.

  8. Quantum-continuum calculation of the surface states and electrical response of silicon in solution

    Science.gov (United States)

    Campbell, Quinn; Dabo, Ismaila

    2017-05-01

    A wide range of electrochemical reactions of practical importance occur at the interface between a semiconductor and an electrolyte. We present an embedded density-functional theory method using the recently released self-consistent continuum solvation (SCCS) approach to study these interfaces. In this model, a quantum description of the surface is incorporated into a continuum representation of the bending of the bands within the electrode. The model is applied to understand the electrical response of silicon electrodes in solution, providing microscopic insights into the low-voltage region, where surface states determine the electrification of the semiconductor electrode.

  9. The spatial distribution of ultraviolet line and continuum emission in Herbig-Haro objects

    Science.gov (United States)

    Lee, M. G.; Boehm, K. H.; Temple, S. D.; Raga, A. C.; Mateo, M. L.

    1988-01-01

    Archival IUE data and monochromatic CCD images in the optical range are used to compare the spatial distribution of UV and optical emission in HH 1, HH 2, HH 24, HH 32, HH 43, and HH 47. For all six objects, the observed UV radiation is shown to originate in the objects themselves. The results indicate that the C IV and semiforbidden emission-line regions are small. Although the continuum in the IUE short-wavelength range displays a distribution that is broader than that of any measured line emission in the UV or optical range, the continuum distribution in the IUE long-wavelength range is quite narrow.

  10. Stress, deformation, conservation, and rheology: a survey of key concepts in continuum mechanics

    Science.gov (United States)

    Major, J.J.

    2013-01-01

    This chapter provides a brief survey of key concepts in continuum mechanics. It focuses on the fundamental physical concepts that underlie derivations of the mathematical formulations of stress, strain, hydraulic head, pore-fluid pressure, and conservation equations. It then shows how stresses are linked to strain and rates of distortion through some special cases of idealized material behaviors. The goal is to equip the reader with a physical understanding of key mathematical formulations that anchor continuum mechanics in order to better understand theoretical studies published in geomorphology.

  11. A semi-continuum model on vibration frequency of silicon nanowires in <111> orientation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hong, E-mail: h-yu@seu.edu.cn; Chen, Hong-Bo [Key Lab of MEMS of Ministry of Education, Nanjing, Jiangsu, 210096 (China)

    2016-06-15

    In this article, a new semi-continuum model is built to describe the fundamental vibration frequency of the silicon nanowires in <111> orientation. The Keating potential model and the discrete nature in the width and the thickness direction of the silicon nanowires in <111> orientation are applied in the new semi-continuum model. Based on the Keating model and the principle of conservation of energy, the vibration frequency of the silicon nanowires with the triangle, the rhombus, and the hexagon cross sections are derived. It is indicated that the calculation results based on this new model are accordant with the simulation results of the software based on molecular dynamics (MD).

  12. Modelos contínuos do solvente: fundamentos Continuum solvation models: fundamentals

    Directory of Open Access Journals (Sweden)

    Josefredo R. Pliego Jr

    2006-06-01

    Full Text Available Continuum solvation models are nowadays widely used in the modeling of solvent effects and the range of applications goes from the calculation of partition coefficients to chemical reactions in solution. The present work presents a detailed explanation of the physical foundations of continuum models. We discuss the polarization of a dielectric and its representation through the volume and surface polarization charges. The Poisson equation for a dielectric was obtained and we have also derived and discuss the apparent surface charge method and its application for free energy of solvation calculations.

  13. Continuum Navier-Stokes modelling of water ow past fullerene molecules

    DEFF Research Database (Denmark)

    Walther, J. H.; Popadic, A.; Koumoutsakos, P.

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest...... as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the computational cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently...

  14. Continuum Navier-Stokes modelling of water flow past fullerene molecules

    DEFF Research Database (Denmark)

    Walther, J. H.; Popadic, A.; Koumoutsakos, P.

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest...... as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the computational cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently...

  15. The spectral energy distribution of powerful starburst galaxies - I. Modelling the radio continuum

    Science.gov (United States)

    Galvin, T. J.; Seymour, N.; Marvil, J.; Filipović, M. D.; Tothill, N. F. H.; McDermid, R. M.; Hurley-Walker, N.; Hancock, P. J.; Callingham, J. R.; Cook, R. H.; Norris, R. P.; Bell, M. E.; Dwarakanath, K. S.; For, B.; Gaensler, B. M.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; Lenc, E.; McKinley, B.; Morgan, J.; Offringa, A. R.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B.; Wu, C.; Zheng, Q.

    2018-02-01

    We have acquired radio-continuum data between 70 MHz and 48 GHz for a sample of 19 southern starburst galaxies at moderate redshifts (0.067 attributed to free-free absorption across multiple regions of star formation with varying optical depths. The decomposed synchrotron and free-free emission components in our sample of galaxies form strong correlations with the total-infrared bolometric luminosities. Finally, we find that without accounting for free-free absorption with turnovers between 90 and 500 MHz the radio continuum at low frequency (ν value of -0.8 for normal galaxies. We suggest this may be caused by an intrinsically steeper cosmic ray distribution.

  16. Effect of substrate on optical bound states in the continuum in 1D photonic structures

    DEFF Research Database (Denmark)

    Sadrieva, Z. F.; Sinev, I. S.; Samusev, A. K.

    2017-01-01

    Optical bound states in the continuum (BIC) are localized states with energy lying above the light line and having infinite lifetime. Any losses taking place in real systems result in transformation of the bound states into resonant states with finite lifetime. In this work, we analyze properties...... into resonant states due to leakage into the diffraction channels opening in the substrate.......Optical bound states in the continuum (BIC) are localized states with energy lying above the light line and having infinite lifetime. Any losses taking place in real systems result in transformation of the bound states into resonant states with finite lifetime. In this work, we analyze properties...

  17. Can quantum lattice be generated through several classical ones superimposed in spacetime continuum?

    OpenAIRE

    Sverdlov, Roman

    2011-01-01

    This paper has few different, but interrelated, goals. At first, we will propose a version of discretization of quantum field theory (Chapter 3). We will write down Lagrangians for sample bosonic fields (Section 3.1) and also attempt to generalize them to fermionic QFT (Section 3.2). At the same time, we will insist that the elements of our discrete space are embedded into a continuum. This will allow us to embed several different "lattices" into the same continuum and view them as separate "...

  18. Universality and the approach to the continuum limit in lattice gauge theory

    CERN Document Server

    De Divitiis, G M; Guagnelli, M; Lüscher, Martin; Petronzio, Roberto; Sommer, Rainer; Weisz, P; Wolff, U; de Divitiis, G; Frezzotti, R; Guagnelli, M; Luescher, M; Petronzio, R; Sommer, R; Weisz, P; Wolff, U

    1995-01-01

    The universality of the continuum limit and the applicability of renormalized perturbation theory are tested in the SU(2) lattice gauge theory by computing two different non-perturbatively defined running couplings over a large range of energies. The lattice data (which were generated on the powerful APE computers at Rome II and DESY) are extrapolated to the continuum limit by simulating sequences of lattices with decreasing spacings. Our results confirm the expected universality at all energies to a precision of a few percent. We find, however, that perturbation theory must be used with care when matching different renormalized couplings at high energies.

  19. Universality and the approach to the continuum limit in lattice gauge theory

    Science.gov (United States)

    de Divitiis, Giulia; Frezzotti, Roberto; Guagnelli, Marco; Lüscher, Martin; Petronzio, Roberto; Sommer, Rainer; Weisz, Peter; Wolff, Ulli

    1995-02-01

    The universality of the continuum limit and the applicability of renormalized perturbation theory are tested in the SU(2) lattice gauge theory by computing two different non-perturbatively defined running couplings over a large range of energies. The lattice data (which were generated on the powerful APE computers at Rome II and DESY) are extrapolated to the continuum limit by simulating sequences of lattices with decreasing spacings. Our results confirm the expected universality at all energies to a precision of a few percent. We find, however, that perturbation theory must be used with care when matching different renormalized couplings at high energies.

  20. Accidental bound states in the continuum in an open Sinai billiard

    Science.gov (United States)

    Pilipchuk, A. S.; Sadreev, A. F.

    2017-02-01

    The fundamental mechanism of the bound states in the continuum is the full destructive interference of two resonances when two eigenlevels of the closed system are crossing. There is, however, a wide class of quantum chaotic systems which display only avoided crossings of eigenlevels. As an example of such a system we consider the Sinai billiard coupled with two semi-infinite waveguides. We show that notwithstanding the absence of degeneracy bound states in the continuum occur due to accidental decoupling of the eigenstates of the billiard from the waveguides.

  1. Forest inventory: role in accountability for sustainable forest management

    Science.gov (United States)

    Lloyd C. Irland

    2007-01-01

    Forest inventory can play several roles in accountability for sustainable forest management. A first dimension is accountability for national performance. The new field of Criteria and Indicators is an expression of this need. A more familiar role for the U.S. Department of Agriculture Forest Service Forest Inventory and Analysis (FIA) program is for assessment and...

  2. Forest resources of the Hoosier National Forest, 2005

    Science.gov (United States)

    Christoper W. Woodall; Judith A. Perez; Thomas R. Thake

    2007-01-01

    The first annual inventory of the Hoosier National Forest reports more than 200,000 forest land acres dominated by oaks, maples, and hickories with annual growth exceeding annual mortality by a factor of seven. When compared to forests in the rest of Indiana, the Hoosier's forests are on average older, have greater biomass per acre, and possess a greater...

  3. degraded forests are more susceptible to forest fires: some possible ...

    African Journals Online (AJOL)

    2006-08-02

    Aug 2, 2006 ... There is a strong belief that degraded forests are, more susceptible to forest fires than non~ degraded ... fire as well as the impact that the fire will have on the forest. When a forest is well protected and a close canopy maintained, its susceptibility to accidental ... human interference in the ecosystem. Swaine ...

  4. Forest structure in low-diversity tropical forests: a study of Hawaiian wet and dry forests.

    Science.gov (United States)

    Ostertag, Rebecca; Inman-Narahari, Faith; Cordell, Susan; Giardina, Christian P; Sack, Lawren

    2014-01-01

    The potential influence of diversity on ecosystem structure and function remains a topic of significant debate, especially for tropical forests where diversity can range widely. We used Center for Tropical Forest Science (CTFS) methodology to establish forest dynamics plots in montane wet forest and lowland dry forest on Hawai'i Island. We compared the species diversity, tree density, basal area, biomass, and size class distributions between the two forest types. We then examined these variables across tropical forests within the CTFS network. Consistent with other island forests, the Hawai'i forests were characterized by low species richness and very high relative dominance. The two Hawai'i forests were floristically distinct, yet similar in species richness (15 vs. 21 species) and stem density (3078 vs. 3486/ha). While these forests were selected for their low invasive species cover relative to surrounding forests, both forests averaged 5->50% invasive species cover; ongoing removal will be necessary to reduce or prevent competitive impacts, especially from woody species. The montane wet forest had much larger trees, resulting in eightfold higher basal area and above-ground biomass. Across the CTFS network, the Hawaiian montane wet forest was similar to other tropical forests with respect to diameter distributions, density, and aboveground biomass, while the Hawai'i lowland dry forest was similar in density to tropical forests with much higher diversity. These findings suggest that forest structural variables can be similar across tropical forests independently of species richness. The inclusion of low-diversity Pacific Island forests in the CTFS network provides an ∼80-fold range in species richness (15-1182 species), six-fold variation in mean annual rainfall (835-5272 mm yr(-1)) and 1.8-fold variation in mean annual temperature (16.0-28.4°C). Thus, the Hawaiian forest plots expand the global forest plot network to enable testing of ecological theory for

  5. Securing tropical forest carbon

    DEFF Research Database (Denmark)

    Scharlemann, Jörn P. W.; Kapos, Valerie; Campbell, Alison

    2010-01-01

    Forest loss and degradation in the tropics contribute 6-17% of all greenhouse gas emissions. Protected areas cover 217.2 million ha (19.6%) of the world's humid tropical forests and contain c. 70.3 petagrams of carbon (Pg C) in biomass and soil to 1 m depth. Between 2000 and 2005, we estimate...... that 1.75 million ha of forest were lost from protected areas in humid tropical forests, causing the emission of 0.25-0.33 Pg C. Protected areas lost about half as much carbon as the same area of unprotected forest. We estimate that the reduction of these carbon emissions from ongoing deforestation...... in protected sites in humid tropical forests could be valued at USD 6,200-7,400 million depending on the land use after clearance. This is >1.5 times the estimated spending on protected area management in these regions. Improving management of protected areas to retain forest cover better may be an important...

  6. 78 FR 23903 - Forest Service

    Science.gov (United States)

    2013-04-23

    ... Forest Service Dixie Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting... recommendations to the Forest Service concerning projects and funding consistent with Title II of the Act. The meeting is open to the public. The purpose of the meeting is to review proposals for forest projects and...

  7. Forest Fuels Management in Europe

    Science.gov (United States)

    Gavriil Xanthopoulos; David Caballero; Miguel Galante; Daniel Alexandrian; Eric Rigolot; Raffaella Marzano

    2006-01-01

    Current fuel management practices vary considerably between European countries. Topography, forest and forest fuel characteristics, size and compartmentalization of forests, forest management practices, land uses, land ownership, size of properties, legislation, and, of course, tradition, are reasons for these differences.Firebreak construction,...

  8. The Challenge of Forest Diagnostics

    Directory of Open Access Journals (Sweden)

    Harini Nagendra

    2011-06-01

    Full Text Available Ecologists and practitioners have conventionally used forest plots or transects for monitoring changes in attributes of forest condition over time. However, given the difficulty in collecting such data, conservation practitioners frequently rely on the judgment of foresters and forest users for evaluating changes. These methods are rarely compared. We use a dataset of 53 forests in five countries to compare assessments of forest change from forest plots, and forester and user evaluations of changes in forest density. We find that user assessments of changes in tree density are strongly and significantly related to assessments of change derived from statistical analyses of randomly distributed forest plots. User assessments of change in density at the shrub/sapling level also relate to assessments derived from statistical evaluations of vegetation plots, but this relationship is not as strong and only weakly significant. Evaluations of change by professional foresters are much more difficult to acquire, and less reliable, as foresters are often not familiar with changes in specific local areas. Forester evaluations can instead better provide valid single-time comparisons of a forest with other areas in a similar ecological zone. Thus, in forests where local forest users are present, their evaluations can be used to provide reliable assessments of changes in tree density in the areas they access. However, assessments of spatially heterogeneous patterns of human disturbance and regeneration at the shrub/sapling level are likely to require supplemental vegetation analysis.

  9. Climate change and forest diseases

    Science.gov (United States)

    R.N. Sturrock; Susan Frankel; A. V. Brown; Paul Hennon; J. T. Kliejunas; K. J. Lewis; J. J. Worrall; A. J. Woods

    2011-01-01

    As climate changes, the effects of forest diseases on forest ecosystems will change. We review knowledge of relationships between climate variables and several forest diseases, as well as current evidence of how climate, host and pathogen interactions are responding or might respond to climate change. Many forests can be managed to both adapt to climate change and...

  10. Forests of east Texas, 2015

    Science.gov (United States)

    Kerry J.W. Dooley

    2017-01-01

    This resource update provides an overview of forest resources in east Texas based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Southern Research Station (SRS) in cooperation with Texas A&M Forest Service. The 254 counties of Texas are consolidated into seven FIA survey units—Southeast (unit 1),...

  11. Forests of East Texas, 2014

    Science.gov (United States)

    Thomas J. Brandeis

    2015-01-01

    This resource update provides an overview of forest resources in east Texas derived from an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) Program at the Southern Research Station in cooperation with the Texas A&M Forest Service. These estimates are based on field data collected using the FIA annualized sample design and are...

  12. A density functional and quantum Monte Carlo study of glutamic acid in vacuo and in a dielectric continuum medium

    NARCIS (Netherlands)

    Floris, F.; Filippi, Claudia; Amovilli, C.

    2012-01-01

    We present density functional theory (DFT) and quantum Monte Carlo (QMC) calculations of the glutamic acid and glutamate ion in vacuo and in various dielectric continuum media within the polarizable continuum model (PCM). In DFT, we employ the integral equation formalism variant of PCM while, in

  13. The quasi-continuum of gamma rays following the decay of superdeformed bands in the Hg region

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Khoo, T.L.; Janssens, R.V.F. [Argonne National Lab., IL (United States)] [and others

    1996-12-31

    The quasi-continuum part of the spectrum associated with the decay-out of the yrast superdeformed band in {sup 194}Hg has been extracted. It has for the first time been possible to compare the spin and excitation energy determined from the analysis of the quasi-continuum {gamma} rays to the exact result obtained from the one-step linking transitions.

  14. Partnering: An Engine for Innovation, Continuum Magazine, Fall 2014 / Issue 7; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    None

    2014-10-01

    This issue of Continuum highlights the many ways NREL partners with private industry and other research institutions. You will find references to many of the partnerships and examples of the scope of our engagement with industry leaders, government organizations, and startups.

  15. Achieving linear scaling in computational cost for a fully polarizable MM/continuum embedding.

    Science.gov (United States)

    Caprasecca, Stefano; Jurinovich, Sandro; Lagardère, Louis; Stamm, Benjamin; Lipparini, Filippo

    2015-02-10

    In this paper, we present a new, efficient implementation of a fully polarizable QM/MM/continuum model based on an induced-dipoles polarizable force field and on the Conductor-like Screening Model as a polarizable continuum in combination with a self-consistent field QM method. The paper focuses on the implementation of the MM/continuum embedding, where the two polarizable methods are fully coupled to take into account their mutual polarization. With respect to previous implementations, we achieve for the first time a linear scaling with respect to both the computational cost and the memory requirements without limitations on the molecular cavity shape. This is achieved thanks to the use of the recently developed ddCOSMO model for the continuum and the Fast Multipole Method for the force field, together with an efficient iterative procedure. Therefore, it becomes possible to include in the classical layer as much as several tens of thousands of atoms with a limited computational effort.

  16. Successful aging as a continuum of functional independence: lessons from physical disability models of aging.

    NARCIS (Netherlands)

    Lowry, K.A.; Vallejo, A.N.; Studenski, S.A.

    2012-01-01

    Successful aging is a multidimensional construct that could be viewed as a continuum of achievement. Based on the disability model proposed by the WHO International Classification of Functioning, Disability and Health, successful aging includes not only the presence or absence of disease, but also

  17. Rural Primary Care Providers' Perceptions of Their Role in the Breast Cancer Care Continuum

    Science.gov (United States)

    Rayman, Kathleen M.; Edwards, Joellen

    2010-01-01

    Context: Rural women in the United States experience disparity in breast cancer diagnosis and treatment when compared to their urban counterparts. Given the 11% chance of lifetime occurrence of breast cancer for women overall, the continuum of breast cancer screening, diagnosis, treatment, and recovery are of legitimate concern to rural women and…

  18. Line Shape Effects on Intensity Measurements of Solar Features: Brightness Correction to SOHO MDI Continuum Images

    NARCIS (Netherlands)

    Criscuoli, S.; Ermolli, I.; Del Moro, D.; Giorgi, F.; Tritschler, A.; Uitenbroek, H.; Vitas, N.

    2011-01-01

    Continuum intensity observations obtained with theMichelson Doppler Imager (MDI) on board the SOHO mission provide long time series of filtergrams that are ideal for studying the evolution of large-scale phenomena in the solar atmosphere and their dependence on solar activity. These filtergrams,

  19. Two Kinds of Scaffolding: The Dialectical Process within the Authenticity-Generalizibility (A-G Continuum

    Directory of Open Access Journals (Sweden)

    Hung W. L. David

    2002-10-01

    Full Text Available Recent developments of situated cognition seem to be incompatible with traditional views of school based-learning where abstract or generalized knowledge is emphasized. In this paper, we are advocating that authenticity (as emphasized by situated cognitivists and generalizibility (as advocated by cognitivists are compatible. From an instructional perspective, it should not be for one or the other, but rather the scaffolding of the dialecticism between authenticity and generalizibility. In this paper, we first discuss the problems relating to the radical view of situated cognition and cognitivist approaches to learning and instruction. We then contend that authenticity and generalizibility are compatible and introduce the notion of the Authenticity-Generalizibility (A-G continuum, where from an instructional perspective, the emphasis should be scaffolding within such a continuum. We hypothesize that learners would have richer and deeper understandings of a subject or domain when they have opportunities to experience the full range of learning activities within the A-G continuum. Finally, we proposed two kinds of IT scaffolds, one to assist student moving towards the authenticity end of the continuum and the other vice versa.

  20. Studying water in the soil-plant-atmosphere continuum: a bibliographic guide to techniques

    CSIR Research Space (South Africa)

    Scholes, RJ

    1989-01-01

    Full Text Available The parameters used to describe the flow of water, and energy to a lesser extent, through the soil-plant-atmosphere continuum are reviewed and the techniques used for estimating their values contrasted. The measurements which are necessary...

  1. Utilization of physiotherapy in the continuum of stroke care at a ...

    African Journals Online (AJOL)

    Objectives: To investigate the pattern of referral for and utilisation of physiotherapy in the continuum of stroke care at a tertiary hospital in Ibadan, Nigeria. Methods: Referral notes and medical records of patients admitted in the University College Hospital, Ibadan with a clinical diagnosis of stroke between January, 2009 and ...

  2. Some thoughts about the desiccation tolerance continuum and the basis for “intermediate” seed physiologies

    Science.gov (United States)

    Desiccation-sensitive seeds succumb when dried below a critical water content. Critical water contents range widely among species and with experimental conditions, implying a continuum in the amount of water that can be non-lethally removed from diverse cells. However, water potentials correspondi...

  3. Continuous Shape Estimation of Continuum Robots Using X-ray Images.

    Science.gov (United States)

    Lobaton, Edgar J; Fu, Jinghua; Torres, Luis G; Alterovitz, Ron

    2013-05-06

    We present a new method for continuously and accurately estimating the shape of a continuum robot during a medical procedure using a small number of X-ray projection images (e.g., radiographs or fluoroscopy images). Continuum robots have curvilinear structure, enabling them to maneuver through constrained spaces by bending around obstacles. Accurately estimating the robot's shape continuously over time is crucial for the success of procedures that require avoidance of anatomical obstacles and sensitive tissues. Online shape estimation of a continuum robot is complicated by uncertainty in its kinematic model, movement of the robot during the procedure, noise in X-ray images, and the clinical need to minimize the number of X-ray images acquired. Our new method integrates kinematics models of the robot with data extracted from an optimally selected set of X-ray projection images. Our method represents the shape of the continuum robot over time as a deformable surface which can be described as a linear combination of time and space basis functions. We take advantage of probabilistic priors and numeric optimization to select optimal camera configurations, thus minimizing the expected shape estimation error. We evaluate our method using simulated concentric tube robot procedures and demonstrate that obtaining between 3 and 10 images from viewpoints selected by our method enables online shape estimation with errors significantly lower than using the kinematic model alone or using randomly spaced viewpoints.

  4. A Continuum of Learning: From Rote Memorization to Meaningful Learning in Organic Chemistry

    Science.gov (United States)

    Grove, Nathaniel P.; Bretz, Stacey Lowery

    2012-01-01

    The Assimilation Theory of Ausubel and Novak has typically been used in the research literature to describe two extremes to learning chemistry: meaningful learning "versus" rote memorization. It is unlikely, however, that such discrete categories of learning exist. Rote and meaningful learning, rather, are endpoints along a continuum of…

  5. Theory of the two-proton radioactivity in the continuum shell model

    OpenAIRE

    Rotureau, J.; Okolowicz, J.; Ploszajczak, M.

    2005-01-01

    We develop the microscopic description of the two-nucleon radioactivity in the framework of the Shell Model Embedded in the Continuum. This approach is applied for the description of spontaneous two-proton radioactivity in $^{45}$Fe, $^{48}$Ni and $^{54}$Zn.

  6. Theory of the two-proton radioactivity in the continuum shell model

    Energy Technology Data Exchange (ETDEWEB)

    Rotureau, J. [Grand Accelerateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen cedex 05 (France); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Joint Institute for Heavy-Ion Research, Oak Ridge, TN 37831 (United States); Okolowicz, J. [Grand Accelerateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen cedex 05 (France); Physics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Ploszajczak, M. [Grand Accelerateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen cedex 05 (France)]. E-mail: ploszajcak@ganil.fr

    2006-03-06

    We develop the microscopic description of the two-nucleon radioactivity in the framework of the shell model embedded in the continuum. This approach is applied for the description of spontaneous two-proton radioactivity in {sup 45}Fe, {sup 48}Ni and {sup 54}Zn.

  7. Coupled continuum modeling of fracture reactivation and induced seismicity during enhanced geothermal operations

    NARCIS (Netherlands)

    Wassing, B.B.T.; Wees, J.D. van; Fokker, P.A.

    2012-01-01

    We developed a coupled code to obtain a better understanding of the role of pore pressure changes in causing fracture reactivation and seismicity during EGS. We implemented constitutive models for fractures in a continuum approach, which is advantageous because of the ease of integration in existing

  8. Mid-Infrared femtosecond filament and three octaves continuum generation in gases

    Directory of Open Access Journals (Sweden)

    Bejot P.

    2013-03-01

    Full Text Available We report experimental and theoretical results on mid-infrared femtosecond pulse filamentation in different gases. Highly efficient generation of a three-octave-wide spectral continuum in argon, covering the main atmospheric transparency windows, is demonstrated and explained.

  9. The Human Immunodeficiency Virus Care Continuum in China: 1985-2015.

    Science.gov (United States)

    Ma, Ye; Dou, Zhihui; Guo, Wei; Mao, Yurong; Zhang, Fujie; McGoogan, Jennifer M; Zhao, Yan; Zhao, Decai; Wu, Yasong; Liu, Zhongfu; Wu, Zunyou

    2017-12-05

    Human immunodeficiency virus (HIV) care continuum attrition is a major global public health challenge. Few studies have examined this problem in resource-limited settings. We aimed to assess cumulative, current, and historical achievement along China's HIV continuum of care. A nationwide, serial cross-sectional study of all individuals with HIV infection diagnosed in China between 1 January 1985 and 31 December 2015 was conducted using data from China's HIV/AIDS information systems. Biennial estimates of the number of persons living with HIV were also used. We defined 7 steps in HIV care continuum as infected (estimated), diagnosed, linked, retained, enrolled, receiving antiretroviral therapy (ART), and virally suppressed. Cumulative, 30-year performance, and biennial performance during the most recent 10 years were examined. A total of 573529 persons diagnosed with HIV infection were included. Cumulatively, 94% were linked, 88% were retained, 73% were enrolled, 67% were receiving ART, and 44% were suppressed. Greatest attrition was observed for adolescents, minorities, and those who reported injecting drug use as their route of infection. Improvement was observed from 2005 to 2015. As of the end of 2015, 68% among those infected were diagnosed, 67% among diagnosed were receiving ART, and 65% among those receiving ART were virally suppressed. After adjusting for those without viral load testing, the proportion suppressed increased to 89%. Despite dramatic improvements, China faces serious challenges in achieving the Joint United Nations Programme on HIV/AIDS 90-90-90 targets, because of substantial attrition along its continuum of HIV care.

  10. Excavating black hole continuum spectrum: Possible signatures of scalar hairs and of higher dimensions

    Science.gov (United States)

    Banerjee, Indrani; Chakraborty, Sumanta; SenGupta, Soumitra

    2017-10-01

    Continuum spectrum from black hole accretion disc holds enormous information regarding the strong gravity regime around the black hole and hence about the nature of gravitational interaction in extreme situations. Since in such strong gravity regime the dynamics of gravity should be modified from the Einstein-Hilbert one, its effect should be imprinted on the continuum spectrum originating from the black hole accretion. To explore the effects of these alternative theories on the black hole continuum spectrum in an explicit manner, we have discussed three alternative gravitational models having their origin in three distinct paradigms—(a) higher dimensions, (b) higher curvature gravity, and (c) generalized Horndeski theories. All of them can have signatures sculptured on the black hole continuum spectrum, distinct from the standard general relativistic scenario. Interestingly all these models exhibit black hole solutions with tidal charge parameter which in these alternative gravity scenarios can become negative, in sharp contrast with the Reissner-Nordström black hole. Using the observational data of optical luminosity for eighty Palomer Green quasars we have illustrated that the difference between the theoretical estimates and the observational results gets minimized for negative values of the tidal charge parameter. As a quantitative estimate of this result we concentrate on several error estimators, including reduced χ2 , Nash-Sutcliffe efficiency, index of agreement etc. Remarkably, all of them indicates a negative value of the tidal charge parameter, signaling the possibility of higher dimensions as well as scalar charge at play in those high gravity regimes.

  11. The Engineering Design Process: Conceptions along the Learning-To-Teach Continuum

    Science.gov (United States)

    Iveland, Ashley

    2017-01-01

    In this study, I sought to identify differences in the views and understandings of engineering design among individuals along the learning-to-teach continuum. To do so, I conducted a comprehensive review of literature to determine the various aspects of engineering design described in the fields of professional engineering and engineering…

  12. Quasi bound states in the continuum with few unit cells of photonic crystal slab

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza; Chung, Il-Sug

    2017-01-01

    Bound states in the continuum (BICs) in photonic crystal slabs represent the resonances with an infinite quality (Q)-factor, occurring above the light line for an infinitely periodic structure. We show that a set of BICs can turn into quasi-BICs with a very high Q-factor even for two or three unit...

  13. A role for health communication in the continuum of HIV care, treatment, and prevention.

    Science.gov (United States)

    Tomori, Cecilia; Risher, Kathryn; Limaye, Rupali J; Van Lith, Lynn M; Gibbs, Susannah; Smelyanskaya, Marina; Celentano, David D

    2014-08-15

    : Health communication has played a pivotal role in HIV prevention efforts since the beginning of the epidemic. The recent paradigm of combination prevention, which integrates behavioral, biomedical, and structural interventions, offers new opportunities for employing health communication approaches across the entire continuum of care. We describe key areas where health communication can significantly enhance HIV treatment, care, and prevention, presenting evidence from interventions that include health communication components. These interventions rely primarily on interpersonal communication, especially individual and group counseling, both within and beyond clinical settings to enhance the uptake of and continued engagement in care. Many successful interventions mobilize a network of trained community supporters or accompagnateurs, who provide education, counseling, psychosocial support, treatment supervision, and other pragmatic assistance across the care continuum. Community treatment supporters reduce the burden on overworked medical providers, engage a wider segment of the community, and offer a more sustainable model for supporting people living with HIV. Additionally, mobile technologies are increasingly seen as promising avenues for ongoing cost-effective communication throughout the treatment cascade. A broader range of communication approaches, traditionally employed in HIV prevention efforts, that address community and sociopolitical levels through mass media, school- or workplace-based education, and entertainment modalities may be useful to interventions seeking to address the full care continuum. Future interventions would benefit from development of a framework that maps appropriate communication theories and approaches onto each step of the care continuum to evaluate the efficacy of communication components on treatment outcomes.

  14. Deliberate Science, Continuum Magazine: Clean Energy Innovation at NREL, Winter 2012 (Book)

    Energy Technology Data Exchange (ETDEWEB)

    2012-02-01

    This quarterly magazine is dedicated to stepping beyond the technical journals to reveal NREL's vital work in a real-world context for our stakeholders. Continuum provides insights into the latest and most impactful clean energy innovations, while spotlighting those talented researchers and unique facilities that make it all happen. This edition focuses on deliberate science.

  15. Interweaving monitoring activities and model development towards enhancing knowledge of the soil-plant-atmosphere continuum

    NARCIS (Netherlands)

    Romano, N.; Angulo-Jaramillo, M.; Javaux, M.; Ploeg, van der M.J.

    2012-01-01

    The guest editors summarize the advances and challenges associated with monitoring and modeling of the soil–plant–atmosphere continuum. They introduce the contributions in the special section, with an emphasis on the scale addressed in each study. The study of water pathways from the soil to the

  16. Modified Continuum Mechanics Modeling on Size-Dependent Properties of Piezoelectric Nanomaterials: A Review

    Directory of Open Access Journals (Sweden)

    Zhi Yan

    2017-01-01

    Full Text Available Piezoelectric nanomaterials (PNs are attractive for applications including sensing, actuating, energy harvesting, among others in nano-electro-mechanical-systems (NEMS because of their excellent electromechanical coupling, mechanical and physical properties. However, the properties of PNs do not coincide with their bulk counterparts and depend on the particular size. A large amount of efforts have been devoted to studying the size-dependent properties of PNs by using experimental characterization, atomistic simulation and continuum mechanics modeling with the consideration of the scale features of the nanomaterials. This paper reviews the recent progresses and achievements in the research on the continuum mechanics modeling of the size-dependent mechanical and physical properties of PNs. We start from the fundamentals of the modified continuum mechanics models for PNs, including the theories of surface piezoelectricity, flexoelectricity and non-local piezoelectricity, with the introduction of the modified piezoelectric beam and plate models particularly for nanostructured piezoelectric materials with certain configurations. Then, we give a review on the investigation of the size-dependent properties of PNs by using the modified continuum mechanics models, such as the electromechanical coupling, bending, vibration, buckling, wave propagation and dynamic characteristics. Finally, analytical modeling and analysis of nanoscale actuators and energy harvesters based on piezoelectric nanostructures are presented.

  17. Global distribution of dissolved organic matter along the aquatic continuum: Across rivers, lakes and oceans

    DEFF Research Database (Denmark)

    Massicotte, Philippe; Asmala, Eero; Stedmon, Colin

    2017-01-01

    and transformation of dissolved organic matter (DOM) along the aquatic continuum across rivers and lakes to oceans. A strong log-linear relationship (R2 = 0.92) between DOC concentration and CDOM absorption at 350 nm was observed at a global scale, but was found to be ecosystem-dependent at local and regional...

  18. Configuration of Style-Dialects in Banaras, India: A Continuum Based on Respect Forms.

    Science.gov (United States)

    Christian, Jane

    This paper compares respect forms used in Bhojpuri, standard Hindi, and suddh Hindi. The role and use of each dialect are described, and a comparison of respect forms used in each is presented, considering phonemic, grammatical, syntactical, suprasegmental, paralinguistic, and kinesic features. The differences noted appear in a continuum among the…

  19. 3D continuum phonon model for group-IV 2D materials

    DEFF Research Database (Denmark)

    Willatzen, Morten; Lew Yan Voon, Lok C.; Gandi, Appala Naidu

    2017-01-01

    A general three-dimensional continuum model of phonons in two-dimensional materials is developed. Our first-principles derivation includes full consideration of the lattice anisotropy and flexural modes perpendicular to the layers and can thus be applied to any two-dimensional material. In this p...

  20. Community-Dwelling Adults versus Older Adults: Psychopathology and the Continuum Hypothesis

    Science.gov (United States)

    Lagana, Luciana; Tramutolo, Carmine; Boncori, Lucia; Cruciani, Anna Clara

    2012-01-01

    Little empirical evidence is available on older adults regarding the existence of a continuum between "normal" personality traits and DSM-IV-TR Axes I and II disorders (American Psychiatric Association, 2000). Given the typical complexity of clinical presentations in advanced age, it is feasible to expect a dimensional conceptualization…