WorldWideScience

Sample records for underlying group structure

  1. On the underlying gauge group structure of D=11 supergravity

    International Nuclear Information System (INIS)

    Bandos, I.A.; Azcarraga, J.A. de; Izquierdo, J.M.; Picon, M.; Varela, O.

    2004-01-01

    The underlying gauge group structure of D=11 supergravity is revisited. It may be described by a one-parametric family of Lie supergroups Σ-bar (s)x-bar SO(1,10), s 0. The family of superalgebras E-bar (s) associated to Σ-bar (s) is given by a family of extensions of the M-algebra {Pa,Qα,Zab,Za1...a5} by an additional fermionic central charge Qα'. The Chevalley-Eilenberg four-cocycle ω4∼Πα-bar Πβ-bar Πa-bar ΠbΓabαβ on the standard D=11 supersymmetry algebra may be trivialized on E-bar (s), and this implies that the three-form field A3 of D=11 supergravity may be expressed as a composite of the Σ-bar (s) one-form gauge fields ea, ψα, Bab, Ba1...a5 and ηα. Two superalgebras of E-bar (s) recover the two earlier D'Auria and Fre decompositions of A3. Another member of E-bar (s) allows for a simpler composite structure for A3 that does not involve the Ba1...a5 field. Σ-bar (s) is a deformation of Σ-bar (0), which is singularized by having an enhanced Sp(32) (rather than just SO(1,10)) automorphism symmetry and by being an expansion of OSp(1 vertical bar 32)

  2. Group III-nitride nanowire structures for photocatalytic hydrogen evolution under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Faqrul A. Chowdhury

    2015-10-01

    Full Text Available The performance of photochemical water splitting over the emerging nanostructured photocatalysts is often constrained by their surface electronic properties, which can lead to imbalance in redox reactions, reduced efficiency, and poor stability. We have investigated the impact of surface charge properties on the photocatalytic activity of InGaN nanowires. By optimizing the surface charge properties through controlled p-type dopant (Mg incorporation, we have demonstrated an apparent quantum efficiency of ∼17.1% and ∼12.3% for InGaN nanowire arrays under visible light irradiation (400 nm–490 nm in aqueous methanol and in the overall neutral-pH water splitting reaction, respectively.

  3. Trajectory grouping structure

    Directory of Open Access Journals (Sweden)

    Maike Buchin

    2015-03-01

    Full Text Available The collective motion of a set of moving entities like people, birds, or other animals, is characterized by groups arising, merging, splitting, and ending. Given the trajectories of these entities, we define and model a structure that captures all of such changes using the Reeb graph, a concept from topology. The trajectory grouping structure has three natural parameters that allow more global views of the data in group size, group duration, and entity inter-distance. We prove complexity bounds on the maximum number of maximal groups that can be present, and give algorithms to compute the grouping structure efficiently. We also study how the trajectory grouping structure can be made robust, that is, how brief interruptions of groups can be disregarded in the global structure, adding a notion of persistence to the structure. Furthermore, we showcase the results of experiments using data generated by the NetLogo flocking model and from the Starkey project. The Starkey data describe the movement of elk, deer, and cattle. Although there is no ground truth for the grouping structure in this data, the experiments show that the trajectory grouping structure is plausible and has the desired effects when changing the essential parameters. Our research provides the first complete study of trajectory group evolvement, including combinatorial,algorithmic, and experimental results.

  4. Structure-function relationships in human testis-determining factor SRY: an aromatic buttress underlies the specific DNA-bending surface of a high mobility group (HMG) box.

    Science.gov (United States)

    Racca, Joseph D; Chen, Yen-Shan; Maloy, James D; Wickramasinghe, Nalinda; Phillips, Nelson B; Weiss, Michael A

    2014-11-21

    Human testis determination is initiated by SRY, a Y-encoded architectural transcription factor. Mutations in SRY cause 46 XY gonadal dysgenesis with female somatic phenotype (Swyer syndrome) and confer a high risk of malignancy (gonadoblastoma). Such mutations cluster in the SRY high mobility group (HMG) box, a conserved motif of specific DNA binding and bending. To explore structure-function relationships, we constructed all possible substitutions at a site of clinical mutation (W70L). Our studies thus focused on a core aromatic residue (position 15 of the consensus HMG box) that is invariant among SRY-related HMG box transcription factors (the SOX family) and conserved as aromatic (Phe or Tyr) among other sequence-specific boxes. In a yeast one-hybrid system sensitive to specific SRY-DNA binding, the variant domains exhibited reduced (Phe and Tyr) or absent activity (the remaining 17 substitutions). Representative nonpolar variants with partial or absent activity (Tyr, Phe, Leu, and Ala in order of decreasing side-chain volume) were chosen for study in vitro and in mammalian cell culture. The clinical mutation (Leu) was found to markedly impair multiple biochemical and cellular activities as respectively probed through the following: (i) in vitro assays of specific DNA binding and protein stability, and (ii) cell culture-based assays of proteosomal degradation, nuclear import, enhancer DNA occupancy, and SRY-dependent transcriptional activation. Surprisingly, however, DNA bending is robust to this or the related Ala substitution that profoundly impairs box stability. Together, our findings demonstrate that the folding, trafficking, and gene-regulatory function of SRY requires an invariant aromatic "buttress" beneath its specific DNA-bending surface. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. The Structure of Group Cohesion.

    Science.gov (United States)

    Cota, Albert A.; And Others

    1995-01-01

    Reviews the literature on unidimensional and multidimensional models of cohesion and describes cohesion as a multidimensional construct with primary and secondary dimensions. Found that primary dimensions described the cohesiveness of all or most types of groups, whereas secondary dimensions only described the cohesiveness of specific types of…

  6. Structural Damage Assessment under Uncertainty

    Science.gov (United States)

    Lopez Martinez, Israel

    Structural damage assessment has applications in the majority of engineering structures and mechanical systems ranging from aerospace vehicles to manufacturing equipment. The primary goals of any structural damage assessment and health monitoring systems are to ascertain the condition of a structure and to provide an evaluation of changes as a function of time as well as providing an early-warning of an unsafe condition. There are many structural heath monitoring and assessment techniques developed for research using numerical simulations and scaled structural experiments. However, the transition from research to real-world structures has been rather slow. One major reason for this slow-progress is the existence of uncertainty in every step of the damage assessment process. This dissertation research involved the experimental and numerical investigation of uncertainty in vibration-based structural health monitoring and development of robust detection and localization methods. The basic premise of vibration-based structural health monitoring is that changes in structural characteristics, such as stiffness, mass and damping, will affect the global vibration response of the structure. The diagnostic performance of vibration-based monitoring system is affected by uncertainty sources such as measurement errors, environmental disturbances and parametric modeling uncertainties. To address diagnostic errors due to irreducible uncertainty, a pattern recognition framework for damage detection has been developed to be used for continuous monitoring of structures. The robust damage detection approach developed is based on the ensemble of dimensional reduction algorithms for improved damage-sensitive feature extraction. For damage localization, the determination of an experimental structural model was performed based on output-only modal analysis. An experimental model correlation technique is developed in which the discrepancies between the undamaged and damaged modal data are

  7. The structure of complex Lie groups

    CERN Document Server

    Lee, Dong Hoon

    2001-01-01

    Complex Lie groups have often been used as auxiliaries in the study of real Lie groups in areas such as differential geometry and representation theory. To date, however, no book has fully explored and developed their structural aspects.The Structure of Complex Lie Groups addresses this need. Self-contained, it begins with general concepts introduced via an almost complex structure on a real Lie group. It then moves to the theory of representative functions of Lie groups- used as a primary tool in subsequent chapters-and discusses the extension problem of representations that is essential for studying the structure of complex Lie groups. This is followed by a discourse on complex analytic groups that carry the structure of affine algebraic groups compatible with their analytic group structure. The author then uses the results of his earlier discussions to determine the observability of subgroups of complex Lie groups.The differences between complex algebraic groups and complex Lie groups are sometimes subtle ...

  8. Invariant subsets under compact quantum group actions

    OpenAIRE

    Huang, Huichi

    2012-01-01

    We investigate compact quantum group actions on unital $C^*$-algebras by analyzing invariant subsets and invariant states. In particular, we come up with the concept of compact quantum group orbits and use it to show that countable compact metrizable spaces with infinitely many points are not quantum homogeneous spaces.

  9. Evaluation consolidated under Financial Group Banca Transilvania

    Directory of Open Access Journals (Sweden)

    Chebac Neculina

    2009-06-01

    Full Text Available One of the components of prudence measures adopted by the competentauthorities with the regulation and supervision of financial markets at national andEuropean level is mandatory consolidation of accounts. Romania as member of theEuropean Union it harmonized national regulations with the European consolidation ofaccounts of companies. For the banks have been issued by the appropriate rules by theregulators authority, concerned by National Bank of Romania. In accordance withnational regulations, companies are required to prepare annual consolidated financialstatements may make such situations according to the regulations or accounting inaccordance with Directive VII of the European Economic Community, underInternational Financial Reporting Standards.

  10. Vitamin D Analogues with a p-Hydroxyphenyl Group at the C25 Position: Crystal Structure of Vitamin D Receptor Ligand-Binding Domain Complexed with the Ligand Explains the Mechanism Underlying Full Antagonistic Action.

    Science.gov (United States)

    Kato, Akira; Yamao, Makiko; Hashihara, Yuta; Ishida, Hiroaki; Itoh, Toshimasa; Yamamoto, Keiko

    2017-10-26

    Vitamin D receptor (VDR) antagonists can be classified into two categories: the first category of VDR antagonists, which do not stabilize the helix 11-12, and the second category of antagonists, which destabilize the helix 6-7 region. To elucidate the mechanism underlying the first category antagonists by using the crystal structure, we designed and synthesized several VDR ligands with a p-hydroxyphenyl group at the C25-position. Of these, 22S-butyl-25-carbonyl analogue 5b and 25-di-p-hydoroxyphenyl analogues 6a,b showed strong antagonistic activity. We succeeded in cocrystallizing the ligand-binding domain of VDR complexed with 5b and found that the structure showed an alternative conformation of the helix 11-12 that explained the mechanism of the first category antagonists. Taking the present and previous studies together, we could elucidate the mechanisms underlying first and second categories antagonists based on individual crystal structures. This study provides significant insights into antagonism against not only VDR but also nuclear receptors.

  11. IVS Working Group 4: VLBI Data Structures

    Science.gov (United States)

    Gipson, John

    2010-01-01

    In 2007 the IVS Directing Board established IVS Working Group 4 on VLBI Data Structures. This note discusses the current VLBI data format, goals for a new format, the history and formation of the Working Group, and a timeline for the development of a new VLBI data format.

  12. Concrete structures under projectile impact

    CERN Document Server

    Fang, Qin

    2017-01-01

    In this book, the authors present their theoretical, experimental and numerical investigations into concrete structures subjected to projectile and aircraft impacts in recent years. Innovative approaches to analyze the rigid, mass abrasive and eroding projectile penetration and perforation are proposed. Damage and failure analyses of nuclear power plant containments impacted by large commercial aircrafts are numerically and experimentally analyzed. Ultra-high performance concrete materials and structures against the projectile impact are developed and their capacities of resisting projectile impact are evaluated. This book is written for the researchers, engineers and graduate students in the fields of protective structures and terminal ballistics.

  13. 42 CFR 408.86 - Responsibilities under group billing arrangement.

    Science.gov (United States)

    2010-10-01

    ... Payment § 408.86 Responsibilities under group billing arrangement. (a) Enrollee responsibilities. (1) The enrollee is still responsible for premium payments; the group payer simply acts as his agent. If the agent... 42 Public Health 2 2010-10-01 2010-10-01 false Responsibilities under group billing arrangement...

  14. Exceptional groups and elementary-particle structures

    International Nuclear Information System (INIS)

    Biedenharn, L.C.; Truini, P.

    1981-09-01

    A new finite-dimensional quantum mechanical space is constructed over the complex octonionic plane using the recently developed algebraic techniques of Jordan pairs and inner ideals. The automorphism group of this structure is E 6 x U(1), realized on precisely two E 6 irreps which is abstracted as a (topless) model for grand unification

  15. Exceptional groups and elementary-particle structures

    Energy Technology Data Exchange (ETDEWEB)

    Biedenharn, L.C.; Truini, P.

    1981-09-01

    A new finite-dimensional quantum mechanical space is constructed over the complex octonionic plane using the recently developed algebraic techniques of Jordan pairs and inner ideals. The automorphism group of this structure is E/sub 6/ x U(1), realized on precisely two E/sub 6/ irreps which is abstracted as a (topless) model for grand unification.

  16. Evolution of groups with a hierarchical structure

    Science.gov (United States)

    Ohnishi, Teruaki

    2012-12-01

    The universal occurrence of a hierarchical structure and its dynamic behavior in various types of group, living or abstract, are discussed. Here the word “group” refers not only to tangible aggregation but also to invisible aggregation of social psychological and of geopolitical meaning. The evolution of these groups is simulated using a model of agents distributed on the lattices of cellular grids. It is assumed that agents, fearing isolation, interact asymmetrically with each other with regard to exchange of “power”. As an indicator of hierarchy, the Gini coefficient is introduced. Example calculations are made for the aggregation, fusion and fission of animal groups, and for the appearance of a powerful empire and the rise and fall of supremacy. It is shown that such abstract objects evolve with time in accordance with the universal rules of groups common to birds and fish.

  17. Action Recognition Using Discriminative Structured Trajectory Groups

    KAUST Repository

    Atmosukarto, Indriyati

    2015-01-06

    In this paper, we develop a novel framework for action recognition in videos. The framework is based on automatically learning the discriminative trajectory groups that are relevant to an action. Different from previous approaches, our method does not require complex computation for graph matching or complex latent models to localize the parts. We model a video as a structured bag of trajectory groups with latent class variables. We model action recognition problem in a weakly supervised setting and learn discriminative trajectory groups by employing multiple instance learning (MIL) based Support Vector Machine (SVM) using pre-computed kernels. The kernels depend on the spatio-temporal relationship between the extracted trajectory groups and their associated features. We demonstrate both quantitatively and qualitatively that the classification performance of our proposed method is superior to baselines and several state-of-the-art approaches on three challenging standard benchmark datasets.

  18. The Accountability of Armed Groups under Human Rights Law

    NARCIS (Netherlands)

    Fortin, K.M.A.

    2015-01-01

    The starting point for this NWOI funded Ph.D. research is the observation that although UN accountability mechanisms are increasingly holding armed groups ‘accountable’ under human rights law, the legal basis for the responsibility of armed groups under human rights law remains controversial

  19. Concrete structures under impact and impulsive loading

    International Nuclear Information System (INIS)

    Plauk, G.

    1982-05-01

    This book contains papers contributed to the RILEM/CEB/IABSE/IASS-Interassociation Symposium on 'Concrete Structures under Impact and Impulsive Loading'. The essential aim of this symposium is to provide an international forum for the exchange of information on existing and current research relating to impact problems as well as to identify areas to which further research activities should be directed. The subject of the symposium is far ranging. Fifty five papers were proposed and arranged in six technical sessions, a task which sometimes posed difficulties for the Organization Committee and the Advisory Group, because some of the papers touched several topics and were difficult to integrate. However, we are confident that these minor difficulties were solved to the satisfaction of everyone involved. Each session of the symposium is devoted to a major subject area and introduced by a distinguished Introductory Reporter. The large international attendance, some 21 countries are represented, and the large number of excellent papers will certainly produce a lively discussion after each session and thus help to further close the gaps in our knowledge about the behaviour of structures and materials under impact and impulsive loading. (orig./RW)

  20. Symplectic structures and dynamical symmetry groups

    International Nuclear Information System (INIS)

    Torres del Castillo, G.F.; Velazquez Q, M.P.

    2004-01-01

    Apart from the total energy, the two-dimensional isotropic harmonic oscillator possesses three independent constants of motion which, with the standard symplectic structure, generates a dynamical symmetry group isomorphic to SU (2). We show that, by suitably redefining the symplectic structure, any of these three constants of motion can be used as a Hamiltonian, and that the remaining two, together with the total energy, generate a dynamical symmetry group isomorphic to SU (1,1). We also show that the standard energy levels of the quantum two-dimensional isotropic harmonic oscillator and their degeneracies are obtained making use of the appropriate representations of SU(1,1), provided that the canonical commutation relations are modified according to the new symplectic structure. Whereas in classical mechanics the different symplectic structures lead to equivalent formulations of the equations of motion, in quantum mechanics the modifications of the commutation relations should be accompanied by modifications in the interpretation of the formalism in order to obtain results equivalent to those found with the common relations. (Author) 12 refs

  1. Structural basis for group A trichothiodystrophy

    Energy Technology Data Exchange (ETDEWEB)

    Kainov, Denis E; Vitorino, Marc; Cavarelli, Jean; Poterszman, Arnaud; Egly, Jean-Marc (CNRS-INSERM)

    2009-06-17

    Patients with the rare neurodevelopmental repair syndrome known as group A trichothiodystrophy (TTD-A) carry mutations in the gene encoding the p8 subunit of the transcription and DNA repair factor TFIIH. Here we describe the crystal structure of a minimal complex between Tfb5, the yeast ortholog of p8, and the C-terminal domain of Tfb2, the yeast p52 subunit of TFIIH. The structure revealed that these two polypeptides adopt the same fold, forming a compact pseudosymmetric heterodimer via a {beta}-strand addition and coiled coils interactions between terminal {alpha}-helices. Furthermore, Tfb5 protects a hydrophobic surface in Tfb2 from solvent, providing a rationale for the influence of p8 in the stabilization of p52 and explaining why mutations that weaken p8-p52 interactions lead to a reduced intracellular TFIIH concentration and a defect in nucleotide-excision repair, a common feature of TTD cells.

  2. Metastable structures and size effects in small group dynamics

    Directory of Open Access Journals (Sweden)

    Rosapia eLauro Grotto

    2014-07-01

    Full Text Available In his seminal works on group dynamics Bion defined a specific therapeutic setting allowing psychoanalytic observations on group phenomena. In describing the setting he proposed that the group was where his voice arrived. This physical limit was later made operative by assuming that the natural dimension of a therapeutic group is around 12 people. Bion introduced a theory of the group aspects of the mind in which proto-mental individual states spontaneously evolve into shared psychological states that are characterized by a series of features: 1 they emerge as a consequence of the natural tendency of (both conscious and unconscious emotions to combine into structured group patterns; 2 they have a certain degree of stability in time; 3 they tend to alternate so that the dissolution of one is rapidly followed by the emergence of another; 4 they can be described in qualitative terms according to the nature of the emotional mix that dominates the state, in structural terms by a kind of typical 'leadership’ pattern, and in 'cognitive’ terms by a set of implicit expectations that are helpful in explaining the group behavior (i.e. the group behaves 'as if’ it was assuming that…. Here we adopt a formal approach derived from Socio-physics in order to explore some of the structural and dynamic properties of this small group dynamics. We will described data from an analytic DS model simulating small group interactions of agents endowed with a very simplified emotional and cognitive dynamic in order to assess the following main points: 1 are metastable collective states allowed to emerge in the model and if so, under which conditions in the parameter space? 3 can these states be differentiated in structural terms? 3 to what extent are the emergent dynamic features of the systems dependent of the system size? We will finally discuss possible future applications of the quantitative descriptions of the interaction structure in the small group clinical

  3. Metastable structures and size effects in small group dynamics.

    Science.gov (United States)

    Lauro Grotto, Rosapia; Guazzini, Andrea; Bagnoli, Franco

    2014-01-01

    In his seminal works on group dynamics Bion defined a specific therapeutic setting allowing psychoanalytic observations on group phenomena. In describing the setting he proposed that the group was where his voice arrived. This physical limit was later made operative by assuming that the natural dimension of a therapeutic group is around 12 people. Bion introduced a theory of the group aspects of the mind in which proto-mental individual states spontaneously evolve into shared psychological states that are characterized by a series of features: (1) they emerge as a consequence of the natural tendency of (both conscious and unconscious) emotions to combine into structured group patterns; (2) they have a certain degree of stability in time; (3) they tend to alternate so that the dissolution of one is rapidly followed by the emergence of another; (4) they can be described in qualitative terms according to the nature of the emotional mix that dominates the state, in structural terms by a kind of typical "leadership" pattern, and in "cognitive" terms by a set of implicit expectations that are helpful in explaining the group behavior (i.e., the group behaves "as if" it was assuming that). Here we adopt a formal approach derived from Socio-physics in order to explore some of the structural and dynamic properties of this small group dynamics. We will described data from an analytic DS model simulating small group interactions of agents endowed with a very simplified emotional and cognitive dynamic in order to assess the following main points: (1) are metastable collective states allowed to emerge in the model and if so, under which conditions in the parameter space? (2) can these states be differentiated in structural terms? (3) to what extent are the emergent dynamic features of the systems dependent of the system size? We will finally discuss possible future applications of the quantitative descriptions of the interaction structure in the small group clinical setting.

  4. Colloidal Aggregate Structure under Shear by USANS

    Science.gov (United States)

    Chatterjee, Tirtha; van Dyk, Antony K.; Ginzburg, Valeriy V.; Nakatani, Alan I.

    2015-03-01

    Paints are complex formulations of polymeric binders, inorganic pigments, dispersants, surfactants, colorants, rheology modifiers, and other additives. A commercially successful paint exhibits a desired viscosity profile over a wide shear rate range from 10-5 s-1 for settling to >104 s-1 for rolling, and spray applications. Understanding paint formulation structure is critical as it governs the paint viscosity profile. However, probing paint formulation structure under shear is a challenging task due to the formulation complexity containing structures with different hierarchical length scales and their alterations under the influence of an external flow field. In this work mesoscale structures of paint formulations under shear are investigated using Ultra Small-Angle Neutron Scattering (rheo-USANS). Contrast match conditions were utilized to independently probe the structure of latex binder particle aggregates and the TiO2 pigment particle aggregates. Rheo-USANS data revealed that the aggregates are fractal in nature and their self-similarity dimensions and correlations lengths depend on the chemistry of the binder particles, the type of rheology modifier present and the shear stress imposed upon the formulation. These results can be explained in the framework of diffusion and reaction limited transient aggregates structure evolution under simple shear.

  5. INFORMATION SYSTEMS OUTSOURCING DECISIONS UNDER FUZZY GROUP DECISION MAKING APPROACH

    OpenAIRE

    S. NAZARI-SHIRKOUHI; A. ANSARINEJAD; SS. MIRI-NARGESI; V. MAJAZI DALFARD; K. REZAIE

    2011-01-01

    During the last decade, information system (IS) outsourcing has emerged as a major issue for organizations. As outsourcing decisions are often based on multicriteria approaches and group decisions, this paper proposes a structured methodology based on Fuzzy group decision making approach to evaluate and select the appropriate information system project (ISP) in an actual case. To achieve our purpose, we argue that seven criteria consisting of risk, management, economics, technology, resource,...

  6. Water Demand Under Alternative Price Structures

    OpenAIRE

    Sheila Olmstead; W. Michael Hanemann; Robert N. Stavins

    2007-01-01

    We estimate the price elasticity of water demand with household-level data, structurally modeling the piecewise-linear budget constraints imposed by increasing-block pricing. We develop a mathematical expression for the unconditional price elasticity of demand under increasing-block prices and compare conditional and unconditional elasticities analytically and empirically. We test the hypothesis that price elasticity may depend on price structure, beyond technical differences in elasticity co...

  7. Efficient Bayesian inference under the structured coalescent.

    Science.gov (United States)

    Vaughan, Timothy G; Kühnert, Denise; Popinga, Alex; Welch, David; Drummond, Alexei J

    2014-08-15

    Population structure significantly affects evolutionary dynamics. Such structure may be due to spatial segregation, but may also reflect any other gene-flow-limiting aspect of a model. In combination with the structured coalescent, this fact can be used to inform phylogenetic tree reconstruction, as well as to infer parameters such as migration rates and subpopulation sizes from annotated sequence data. However, conducting Bayesian inference under the structured coalescent is impeded by the difficulty of constructing Markov Chain Monte Carlo (MCMC) sampling algorithms (samplers) capable of efficiently exploring the state space. In this article, we present a new MCMC sampler capable of sampling from posterior distributions over structured trees: timed phylogenetic trees in which lineages are associated with the distinct subpopulation in which they lie. The sampler includes a set of MCMC proposal functions that offer significant mixing improvements over a previously published method. Furthermore, its implementation as a BEAST 2 package ensures maximum flexibility with respect to model and prior specification. We demonstrate the usefulness of this new sampler by using it to infer migration rates and effective population sizes of H3N2 influenza between New Zealand, New York and Hong Kong from publicly available hemagglutinin (HA) gene sequences under the structured coalescent. The sampler has been implemented as a publicly available BEAST 2 package that is distributed under version 3 of the GNU General Public License at http://compevol.github.io/MultiTypeTree. © The Author 2014. Published by Oxford University Press.

  8. Expeditionary Strike Group: Command Structure Design Support

    National Research Council Canada - National Science Library

    Hutchins, Susan G; Kemple, William G; Kleinman, David L; Hocevar, Susan P

    2005-01-01

    An Expeditionary Strike Group (ESG) is a new capability mix that combines the combat power of three surface combatants and one submarine with an Amphibious Readiness Group/ Marine Expeditionary Unit...

  9. Sandwich Structures from Arbitrary Functions in Group Theory

    OpenAIRE

    Hawthorn, Ian

    2017-01-01

    Functions between groups with the property that all function con- jugates are inverse preserving are called sandwich morphisms. These maps pre- serve a structure within the group known as the sandwich structure. Sandwich structures are left distributive idempotent left involutary magmas. These pro- vide a generalisation of groups which we call a sandwich. This paper explores sandwiches and their relationship to groups.

  10. Structure analysis of group I plant nucleases

    Czech Academy of Sciences Publication Activity Database

    Dohnálek, Jan; Kovaľ, Tomáš; Lipovová, P.; Podzimek, Tomáš; Matoušek, Jaroslav

    2011-01-01

    Roč. 18, Part 1 (2011), s. 29-30 ISSN 0909-0495. [International Symposium on Diffraction Structural Biology /3./. Paris - Orsay, 25.05.2010-28.05.2010] R&D Projects: GA ČR GA310/09/1407; GA ČR GA521/09/1214 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z10100521; CEZ:AV0Z50510513 Keywords : nuclease * protein structure * crystal structure Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.726, year: 2011

  11. Thermomechanics of composite structures under high temperatures

    CERN Document Server

    Dimitrienko, Yu I

    2016-01-01

    This pioneering book presents new models for the thermomechanical behavior of composite materials and structures taking into account internal physico-chemical transformations such as thermodecomposition, sublimation and melting at high temperatures (up to 3000 K). It is of great importance for the design of new thermostable materials and for the investigation of reliability and fire safety of composite structures. It also supports the investigation of interaction of composites with laser irradiation and the design of heat-shield systems. Structural methods are presented for calculating the effective mechanical and thermal properties of matrices, fibres and unidirectional, reinforced by dispersed particles and textile composites, in terms of properties of their constituent phases. Useful calculation methods are developed for characteristics such as the rate of thermomechanical erosion of composites under high-speed flow and the heat deformation of composites with account of chemical shrinkage. The author expan...

  12. Fatigue in Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    1999-01-01

    test results. Both the fracture mechanics analysis and the fatigue test results indicate that Miner's rule, which is normally used in the design against fatigue in steel structures, may give results, which are unconservative, and that the validity of the results obtained from Miner's rule will depend......Fatigue damage accumulation in steel structures under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series have been carried through on various...... types of welded plate test specimens and full-scale offshore tubular joints. The materials that have been used are either conventional structural steel with a yield stress of ~ 360-410 MPa or high-strength steel with a yield stress of ~ 810-1010 MPa. The fatigue tests and the fracture mechanics analyses...

  13. Structured Learning Teams: Reimagining Student Group Work

    Science.gov (United States)

    Lendvay, Gregory C.

    2014-01-01

    Even in a standards-based curriculum, teachers can apply constructivist practices such as structured learning teams. In this environment, students become invested in the learning aims, triggering the desire in students to awaken, get information, interpret, remix, share, and design scenarios.

  14. Dynamic Group Diffie-Hellman Key Exchange under standard assumptions

    International Nuclear Information System (INIS)

    Bresson, Emmanuel; Chevassut, Olivier; Pointcheval, David

    2002-01-01

    Authenticated Diffie-Hellman key exchange allows two principals communicating over a public network, and each holding public-private keys, to agree on a shared secret value. In this paper we study the natural extension of this cryptographic problem to a group of principals. We begin from existing formal security models and refine them to incorporate major missing details (e.g., strong-corruption and concurrent sessions). Within this model we define the execution of a protocol for authenticated dynamic group Diffie-Hellman and show that it is provably secure under the decisional Diffie-Hellman assumption. Our security result holds in the standard model and thus provides better security guarantees than previously published results in the random oracle model

  15. STABILITY OF UNDERWATER STRUCTURE UNDER WAVE ATTACK

    Directory of Open Access Journals (Sweden)

    C. Paotonan

    2012-02-01

    Full Text Available Geotube is, among others, a type of coastal structure that is increasingly accepted for coastal protection especially underwater breakwater. Besides its relatively low cost, it has other advantages such as flexibility, ease of construction and the fact that it can be filled with local sand material. Similar to all other coastal structures, it should also be stable under wave attack. A simple theoretical approach based on linear wave was adopted to estimate the stability of such structure. The theoretical solution was then compared with an experimental study. The experimental study was conducted at the Hydraulics and Hydrology Laboratory of Universitas Gadjah Mada. However, instead of a real geotube, PVC pipe was used where the weight of the PVC was varied by adjusting the volume of sand in the pipe. The result indicated that the agreement between the theoretical solution and the experiment was encouraging. The analytical solution may be utilized to predict underwater pipe stability under wave attack with certain degree of accuracy.

  16. Strength of concrete structures under dynamic loading

    Science.gov (United States)

    Kumpyak, O. G.; Galyautdinov, Z. R.; Kokorin, D. N.

    2016-01-01

    The use of elastic supports is one the efficient methods of decreasing the dynamic loading. The paper describes the influence of elastic supports on the stress-strain state of steel concrete structures exposed to one-time dynamic loading resulting in failure. Oblique bending beams on elastic supports and their elastic, elastoplastic, and elastoplastic consolidation behavior are considered in this paper. For numerical calculations the developed computer program is used based on the finite element method. Research findings prove high efficiency of elastic supports under dynamic loading conditions. The most effective behavior of elastic supports is demonstrated at the elastoplastic stage. A good agreement is observed between the theoretical and experimental results.

  17. Structuring agreements for seismic group shoots

    International Nuclear Information System (INIS)

    Keeping, C.E.

    1999-01-01

    Sigma Explorations Inc. sells licenses to use Sigma owned seismic data. The company participates with exploration and production companies in the joint acquisition of semi-private participation surveys. This paper discusses three major types of seismic group shoots and the essential elements of the agreements that govern or should govern them. They are: (1) exploration and production company joint ventures, (2) publicly offered spec shoots, and (3) semi-private participation surveys. The key issue with the exploration and production company joint ventures is that the companies are owners of the seismic data in proportion to their contribution towards the cost of the program. Their use of the data should be restricted to those situations permitted by the other owners. These are not often well documented, and there is much concern in the industry as a result. The key issue with publicly offered spec shoots is that the seismic company ultimately owns the data and the client exploration and production company is a licensee and must behave as such. In most such cases the rights and responsibilities are well documented in formal agreements that are signed in advance of the program's beginning date

  18. Structural behavior of supercritical fluids under confinement

    Science.gov (United States)

    Ghosh, Kanka; Krishnamurthy, C. V.

    2018-01-01

    The existence of the Frenkel line in the supercritical regime of a Lennard-Jones (LJ) fluid shown through molecular dynamics (MD) simulations initially and later corroborated by experiments on argon opens up possibilities of understanding the structure and dynamics of supercritical fluids in general and of the Frenkel line in particular. The location of the Frenkel line, which demarcates two distinct physical states, liquidlike and gaslike within the supercritical regime, has been established through MD simulations of the velocity autocorrelation (VACF) and radial distribution function (RDF). We, in this article, explore the changes in the structural features of supercritical LJ fluid under partial confinement using atomistic walls. The study is carried out across the Frenkel line through a series of MD simulations considering a set of thermodynamics states in the supercritical regime (P =5000 bar, 240 K ≤T ≤1500 K ) of argon well above the critical point. Confinement is partial, with atomistic walls located normal to z and extending to "infinity" along the x and y directions. In the "liquidlike" regime of the supercritical phase, particles are found to be distributed in distinct layers along the z axis with layer spacing less than one atomic diameter and the lateral RDF showing amorphous-like structure for specific spacings (packing frustration) and non-amorphous-like structure for other spacings. Increasing the rigidity of the atomistic walls is found to lead to stronger layering and increased structural order. For confinement with reflective walls, layers are found to form with one atomic diameter spacing and the lateral RDF showing close-packed structure for the smaller confinements. Translational order parameter and excess entropy assessment confirms the ordering taking place for atomistic wall and reflective wall confinements. In the "gaslike" regime of the supercritical phase, particle distribution along the spacing and the lateral RDF exhibit features

  19. Energy group structure determination using particle swarm optimization

    International Nuclear Information System (INIS)

    Yi, Ce; Sjoden, Glenn

    2013-01-01

    Highlights: ► Particle swarm optimization is applied to determine broad group structure. ► A graph representation of the broad group structure problem is introduced. ► The approach is tested on a fuel-pin model. - Abstract: Multi-group theory is widely applied for the energy domain discretization when solving the Linear Boltzmann Equation. To reduce the computational cost, fine group cross libraries are often down-sampled into broad group cross section libraries. Cross section data collapsing generally involves two steps: Firstly, the broad group structure has to be determined; secondly, a weighting scheme is used to evaluate the broad cross section library based on the fine group cross section data and the broad group structure. A common scheme is to average the fine group cross section weighted by the fine group flux. Cross section collapsing techniques have been intensively researched. However, most studies use a pre-determined group structure, open based on experience, to divide the neutron energy spectrum into thermal, epi-thermal, fast, etc. energy range. In this paper, a swarm intelligence algorithm, particle swarm optimization (PSO), is applied to optimize the broad group structure. A graph representation of the broad group structure determination problem is introduced. And the swarm intelligence algorithm is used to solve the graph model. The effectiveness of the approach is demonstrated using a fuel-pin model

  20. Different groups, different motives: identity motives underlying changes in identification with novel groups.

    Science.gov (United States)

    Easterbrook, Matt; Vignoles, Vivian L

    2012-08-01

    Social identification is known to have wide-reaching implications, but theorists disagree about the underlying motives. Integrating motivated identity construction theory with recent social identity research, the authors predicted which motives underlie identification with two types of groups: interpersonal networks and social categories. In a five-wave longitudinal study of social identity processes among 268 new university residents, multilevel analyses showed that motives involved in identity enactment processes--self-esteem, belonging, and efficacy--significantly predicted within-person changes in identification with flatmates (an interpersonal network group), whereas motives involved in identity definition processes--meaning, self-esteem, and distinctiveness--significantly predicted within-person changes in identification with halls of residence (an abstract social category). This article discusses implications for research into identity motives and social identity.

  1. Structural modifications of spinels under radiation

    International Nuclear Information System (INIS)

    Quentin, A.

    2010-12-01

    This work is devoted to the study of spinel structure materials under radiation. For that purpose, samples of polycrystalline ZnAl 2 O 4 and monocrystalline MgAl 2 O 4 were irradiated by different heavy ions with different energies. Samples of ZnAl 2 O 4 were studied par electron transmission microscopy, and by grazing incidence X-Ray diffraction and Rietveld analysis. Samples of MgAl 2 O 4 were studied by optical spectroscopy. Most of the results concern amorphization and crystalline structure modification of ZnAl 2 O 4 especially the inversion. We were able to determine a stopping power threshold for amorphization, between 11 keV/nm and 12 keV/nm, and also the amorphization process, which is a multiple impacts process. We studied the evolution of the amorphous phase by TEM and showed a nano-patterning phenomenon. Concerning the inversion, we determined that it did happen by a single impact process, and the saturation value did not reach the random cation distribution value. Inversion and amorphization have different, but close, stopping power threshold. However, amorphization seems to be conditioned by a pre-damage of the material which consists in inversion. (author)

  2. Structuring group medical practices: shareholder and partnership agreements.

    Science.gov (United States)

    Gassman, A S

    1992-01-01

    This article is the second in a series addressing the structuring of group medical entities, shareholder relationships, and general representation factors. In this article, a number of the legal and business considerations for entering into shareholder and partnership agreements are discussed, and various types of practice structures and recommended group practice agreement provisions are described.

  3. Group Membership Modulates the Neural Circuitry Underlying Third Party Punishment.

    Science.gov (United States)

    Morese, Rosalba; Rabellino, Daniela; Sambataro, Fabio; Perussia, Felice; Valentini, Maria Consuelo; Bara, Bruno G; Bosco, Francesca M

    2016-01-01

    This research aims to explore the neural correlates involved in altruistic punishment, parochial altruism and anti-social punishment, using the Third-Party Punishment (TPP) game. In particular, this study considered these punishment behaviors in in-group vs. out-group game settings, to compare how people behave with members of their own national group and with members of another national group. The results showed that participants act altruistically to protect in-group members. This study indicates that norm violation in in-group (but not in out-group) settings results in increased activity in the medial prefrontal cortex and temporo-parietal junction, brain regions involved in the mentalizing network, as the third-party attempts to understand or justify in-group members' behavior. Finally, exploratory analysis during anti-social punishment behavior showed brain activation recruitment of the ventromedial prefrontal cortex, an area associated with altered regulation of emotions.

  4. Structured Peer Group Practicum Supervision: Supervisees' Perceptions of Supervision Theory.

    Science.gov (United States)

    Starling, Paulette V.; Baker, Stanley B.

    2000-01-01

    Discusses a thematic analysis of retrospective phenomenological interviews with four group counseling practicum participants. Suggests the importance of peer feedback supports experimenting with different approaches to the group process. Recommends future research on the impact of group counseling practicum supervision be structured to allow…

  5. On superspinor structure of homogeneous superspace of orthosymplectic groups

    International Nuclear Information System (INIS)

    Volkov, D.V.; Soroka, V.A.; Tkach, V.I.

    1984-01-01

    Superspinor structure of homogeneous superspaces of orthosymplectic groups are considered. It is shown how the properties of orthosymplectic group superspaces of OSp(N, 2K) group playing an important role in the supersymmetry theory can be described using superspinors. An example confirming a possibility of the relation between . canonical ratios of Butten bracket and conventional methods of quantization is considered

  6. Multivariate sparse group lasso for the multivariate multiple linear regression with an arbitrary group structure.

    Science.gov (United States)

    Li, Yanming; Nan, Bin; Zhu, Ji

    2015-06-01

    We propose a multivariate sparse group lasso variable selection and estimation method for data with high-dimensional predictors as well as high-dimensional response variables. The method is carried out through a penalized multivariate multiple linear regression model with an arbitrary group structure for the regression coefficient matrix. It suits many biology studies well in detecting associations between multiple traits and multiple predictors, with each trait and each predictor embedded in some biological functional groups such as genes, pathways or brain regions. The method is able to effectively remove unimportant groups as well as unimportant individual coefficients within important groups, particularly for large p small n problems, and is flexible in handling various complex group structures such as overlapping or nested or multilevel hierarchical structures. The method is evaluated through extensive simulations with comparisons to the conventional lasso and group lasso methods, and is applied to an eQTL association study. © 2015, The International Biometric Society.

  7. Reinforcing Visual Grouping Cues to Communicate Complex Informational Structure.

    Science.gov (United States)

    Bae, Juhee; Watson, Benjamin

    2014-12-01

    In his book Multimedia Learning [7], Richard Mayer asserts that viewers learn best from imagery that provides them with cues to help them organize new information into the correct knowledge structures. Designers have long been exploiting the Gestalt laws of visual grouping to deliver viewers those cues using visual hierarchy, often communicating structures much more complex than the simple organizations studied in psychological research. Unfortunately, designers are largely practical in their work, and have not paused to build a complex theory of structural communication. If we are to build a tool to help novices create effective and well structured visuals, we need a better understanding of how to create them. Our work takes a first step toward addressing this lack, studying how five of the many grouping cues (proximity, color similarity, common region, connectivity, and alignment) can be effectively combined to communicate structured text and imagery from real world examples. To measure the effectiveness of this structural communication, we applied a digital version of card sorting, a method widely used in anthropology and cognitive science to extract cognitive structures. We then used tree edit distance to measure the difference between perceived and communicated structures. Our most significant findings are: 1) with careful design, complex structure can be communicated clearly; 2) communicating complex structure is best done with multiple reinforcing grouping cues; 3) common region (use of containers such as boxes) is particularly effective at communicating structure; and 4) alignment is a weak structural communicator.

  8. Peer influence: Neural mechanisms underlying in-group conformity

    Directory of Open Access Journals (Sweden)

    Mirre eStallen

    2013-03-01

    Full Text Available People often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI. Participants completed a perceptual decision-making task while undergoing fMRI, during which they were exposed to the judgments of both in-group and out-group members. Our data suggest that conformity to the in-group is mediated by both positive affect as well as the cognitive capacity of perspective taking. Examining the processes that drive in-group conformity by utilizing a basic decision-making paradigm combined with neuroimaging methods provides important insights into the potential mechanisms of conformity. These results may provide an integral step in developing more effective campaigns using group conformity as a tool for behavioral change.

  9. Peer influence: neural mechanisms underlying in-group conformity.

    Science.gov (United States)

    Stallen, Mirre; Smidts, Ale; Sanfey, Alan G

    2013-01-01

    People often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI). Participants completed a perceptual decision-making task while undergoing fMRI, during which they were exposed to the judgments of both in-group and out-group members. Our data suggest that conformity to the in-group is mediated by both positive affect as well as the cognitive capacity of perspective taking. Examining the processes that drive in-group conformity by utilizing a basic decision-making paradigm combined with neuroimaging methods provides important insights into the potential mechanisms of conformity. These results may provide an integral step in developing more effective campaigns using group conformity as a tool for behavioral change.

  10. Higher dimensional gravity invariant under the Poincare group

    International Nuclear Information System (INIS)

    Salgado, P.; Cataldo, M.; Campo, S. del

    2002-01-01

    It is shown that the Stelle-West Grignani-Nardelli formalism allows, both when odd dimensions and when even dimensions are considered, constructing actions for higher dimensional gravity invariant under local Lorentz rotations and under local Poincare translations. It is also proved that such actions have the same coefficients as those obtained by Troncoso and Zanelli [Class. Quantum Grav. 17, 4451 (2000)

  11. Magnetic structures of erbium under high pressure

    DEFF Research Database (Denmark)

    Kawano, S.; Lebech, B.; Achiwa, N.

    1993-01-01

    Neutron diffraction studies of the magnetic structures of erbium metal at 4.5 K and 11.5 kbar hydrostatic pressure have revealed that the transition to a conical structure at low temperatures is suppressed and that the cycloidal structure, with modulation vector Q congruent-to (2/7 2pi/c)c persists...

  12. Electronic structure of Ca, Sr, and Ba under pressure.

    Science.gov (United States)

    Animalu, A. O. E.; Heine, V.; Vasvari, B.

    1967-01-01

    Electronic band structure calculations phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure

  13. Stress Management and Nuclear Anxiety: A Structured Group Experience.

    Science.gov (United States)

    Bisio, Thomas A.; Crisan, Pamela

    1984-01-01

    Describes a structured workshop in which group members explore their fears of nuclear holocaust and the effects this fear has had on their lives. By using logotherapy ideals, the participants create a renewed sense of purpose and hope. (Author)

  14. Response of masonry structure under impact load

    International Nuclear Information System (INIS)

    Makovicka, D.

    1993-01-01

    The paper deals with interaction of a short gaseous impact wave with a plate structure. Analyses of dynamic bending, depending on the parameters of the structure and the impact wave (i.e. the stress and displacement field produced by the resulting incident and reflected wave) have been made by FEM. The calculated data was based on the real material properties of this structure. Pressures greater than computed limit pressures result in the failure of the structure. The calculated and experimental data are compared. (author)

  15. Group Performance in Military Scenarios Under Deceptive Conditions

    National Research Council Canada - National Science Library

    Hass, Michael

    2004-01-01

    .... One hundred and eight participants were grouped into teams of three, given similar instructions but different goals, and asked to play a cooperative game called StrikeCOM that mimics the intelligence...

  16. Blade Group Fatigue Life Calculation under Resonant Stresses

    Directory of Open Access Journals (Sweden)

    Zlatko Petreski

    2017-02-01

    Full Text Available The results of the simulations of the blade group resonant stresses in a FE environment and fatigue life calculation are presented in this paper. Numerical calculation for determination of natural frequencies, mode shapes and dynamic stresses, based on FEM and NISA package is used. Analyses are made on the blade group with three blades with rectangular cross section and typical turbine blades with taper, pretwist and asymmetric airfoil as well. The influence of the position of the lacing wire on the resonant stresses is analyzed. Three-dimensional finite element models of the blade group are made by using twenty node isoparametric solid elements. The number of degrees of freedom is different for each model (more than 30000 DOF. The fatigue life and consequent life prediction according the stress load history of the blades is made. The results of the investigation are given in tables and graphics.

  17. Structural features and electronic properties of group-III-, group-IV-, and group-V-doped Si nanocrystallites

    International Nuclear Information System (INIS)

    Ramos, L E; Degoli, Elena; Cantele, G; Ossicini, Stefano; Ninno, D; Furthmueller, J; Bechstedt, F

    2007-01-01

    We investigate the incorporation of group-III (B and Al), group-IV (C and Ge), and group-V (N and P) impurities in Si nanocrystallites. The structural features and electronic properties of doped Si nanocrystallites, which are faceted or spherical-like, are studied by means of an ab initio pseudopotential method including spin polarization. Jahn-Teller distortions occur in the neighborhood of the impurity sites and the bond lengths show a dependence on size and shape of the nanocrystallites. We find that the acceptor (group-III) and donor (group-V) levels become deep as the nanocrystallites become small. The energy difference between the spin-up and spin-down levels of group-III and group-V impurities decreases as the size of the Si nanocrystallite increases and tends to the value calculated for Si bulk. Doping with carbon introduces an impurity-related level in the energy gap of the Si nanocrystallites

  18. Peer influence: neural mechanisms underlying in-group conformity

    NARCIS (Netherlands)

    Stallen, M.; Smidts, A.; Sanfey, A.G.

    2013-01-01

    People often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI). Participants completed

  19. Peer influence: Neural mechanisms underlying in-group conformity

    NARCIS (Netherlands)

    M. Stallen (Mirre); A. Smidts (Ale); A.G. Sanfey (Alan)

    2013-01-01

    textabstractPeople often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI).

  20. Interaction rules underlying group decisions in homing pigeons

    Science.gov (United States)

    Pettit, Benjamin; Perna, Andrea; Biro, Dora; Sumpter, David J. T.

    2013-01-01

    Travelling in groups gives animals opportunities to share route information by following cues from each other's movement. The outcome of group navigation will depend on how individuals respond to each other within a flock, school, swarm or herd. Despite the abundance of modelling studies, only recently have researchers developed techniques to determine the interaction rules among real animals. Here, we use high-resolution GPS (global positioning system) tracking to study these interactions in pairs of pigeons flying home from a familiar site. Momentary changes in velocity indicate alignment with the neighbour's direction, as well as attraction or avoidance depending on distance. Responses were stronger when the neighbour was in front. From the flocking behaviour, we develop a model to predict features of group navigation. Specifically, we show that the interactions between pigeons stabilize a side-by-side configuration, promoting bidirectional information transfer and reducing the risk of separation. However, if one bird gets in front it will lead directional choices. Our model further predicts, and observations confirm, that a faster bird (as measured from solo flights) will fly slightly in front and thus dominate the choice of homing route. Our results explain how group decisions emerge from individual differences in homing flight behaviour. PMID:24068173

  1. Group size, grooming and fission in primates: a modeling approach based on group structure.

    Science.gov (United States)

    Sueur, Cédric; Deneubourg, Jean-Louis; Petit, Odile; Couzin, Iain D

    2011-03-21

    In social animals, fission is a common mode of group proliferation and dispersion and may be affected by genetic or other social factors. Sociality implies preserving relationships between group members. An increase in group size and/or in competition for food within the group can result in decrease certain social interactions between members, and the group may split irreversibly as a consequence. One individual may try to maintain bonds with a maximum of group members in order to keep group cohesion, i.e. proximity and stable relationships. However, this strategy needs time and time is often limited. In addition, previous studies have shown that whatever the group size, an individual interacts only with certain grooming partners. There, we develop a computational model to assess how dynamics of group cohesion are related to group size and to the structure of grooming relationships. Groups' sizes after simulated fission are compared to observed sizes of 40 groups of primates. Results showed that the relationship between grooming time and group size is dependent on how each individual attributes grooming time to its social partners, i.e. grooming a few number of preferred partners or grooming equally or not all partners. The number of partners seemed to be more important for the group cohesion than the grooming time itself. This structural constraint has important consequences on group sociality, as it gives the possibility of competition for grooming partners, attraction for high-ranking individuals as found in primates' groups. It could, however, also have implications when considering the cognitive capacities of primates. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Kin groups and trait groups: population structure and epidemic disease selection.

    Science.gov (United States)

    Fix, A G

    1984-10-01

    A Monte Carlo simulation based on the population structure of a small-scale human population, the Semai Senoi of Malaysia, has been developed to study the combined effects of group, kin, and individual selection. The population structure resembles D.S. Wilson's structured deme model in that local breeding populations (Semai settlements) are subdivided into trait groups (hamlets) that may be kin-structured and are not themselves demes. Additionally, settlement breeding populations are connected by two-dimensional stepping-stone migration approaching 30% per generation. Group and kin-structured group selection occur among hamlets the survivors of which then disperse to breed within the settlement population. Genetic drift is modeled by the process of hamlet formation; individual selection as a deterministic process, and stepping-stone migration as either random or kin-structured migrant groups. The mechanism for group selection is epidemics of infectious disease that can wipe out small hamlets particularly if most adults become sick and social life collapses. Genetic resistance to a disease is an individual attribute; however, hamlet groups with several resistant adults are less likely to disintegrate and experience high social mortality. A specific human gene, hemoglobin E, which confers resistance to malaria, is studied as an example of the process. The results of the simulations show that high genetic variance among hamlet groups may be generated by moderate degrees of kin-structuring. This strong microdifferentiation provides the potential for group selection. The effect of group selection in this case is rapid increase in gene frequencies among the total set of populations. In fact, group selection in concert with individual selection produced a faster rate of gene frequency increase among a set of 25 populations than the rate within a single unstructured population subject to deterministic individual selection. Such rapid evolution with plausible rates of

  3. Structure and Dynamics of Humpback Whales Competitive Groups in Ecuador

    Directory of Open Access Journals (Sweden)

    Fernando Félix

    2015-02-01

    Full Text Available We assessed the social structure and behavior of humpback whale (Megaptera novaeangliae competitive groups off Ecuador between July and August 2010. During this time we followed 185 whales in 22 competitive groups for 41.45 hr. The average group size was 8.4 animals (SD = 2.85. The average sighting time was 113.05 min/group (SD = 47.1. We used photographs of dorsal fins and video to record interactions and estimate an association index (AI between each pair of whales within the groups. Sightings were divided into periods, which were defined by changes in group membership. On average, group composition changed every 30.2 min, which confirms that the structure of competitive groups is highly dynamic. Interactions between escorts characterized by low level of aggression. At least 60% of escorts joined or left together the group in small subunits between two and five animals, suggesting some type of cooperative association. Although singletons, as well as pairs or trios were able to join competitive groups at any moment, escorts that joined together were able to stay longer with the group and displace dominant escorts. Genetic analysis showed that in three occasions more than one female was present within a competitive group, suggesting either males are herding females or large competitive groups are formed by subunits. Males and females performed similar surface displays. We propose that competition and cooperation are interrelated in humpback whales’ competitive groups and that male cooperation would be an adaptive strategy either to displace dominant escorts or to fend off challengers.

  4. Structure of polymer chains under confinement

    Indian Academy of Sciences (India)

    cluded volume interactions (so-called regime of “semi-dilute cigars”). For confined charged polymers, a peak is observed whose intensity increases with molecular weight and the asymptotic 1/q scattering region is extended compared to the bulk. We infer that the chains are sufficiently extended, under the influence of ...

  5. The monster sporadic group and a theory underlying superstring models

    International Nuclear Information System (INIS)

    Chapline, G.

    1996-09-01

    The pattern of duality symmetries acting on the states of compactified superstring models reinforces an earlier suggestion that the Monster sporadic group is a hidden symmetry for superstring models. This in turn points to a supersymmetric theory of self-dual and anti-self-dual K3 manifolds joined by Dirac strings and evolving in a 13 dimensional spacetime as the fundamental theory. In addition to the usual graviton and dilaton this theory contains matter-like degrees of freedom resembling the massless states of the heterotic string, thus providing a completely geometric interpretation for ordinary matter. 25 refs

  6. Group points to underlying causes of ecosystem, blodiversity loss

    Science.gov (United States)

    Showstack, Randy

    Freshwater diversion, urban water pollution,and overfishing are leading to the decline of some of Pakistan's coastal mangrove ecosystems. In Mexico's Calakmul Biosphere Reserve, near the border of Guatemala, population growth and poverty are pushing forest clearing. Meanwhile, in Chilika Lake in southeast India, changes in economic policies and global markets have led to changes in commercial aquaculture that is partly responsible for the decline of local fisheries and the bird population.These are the conclusions of some of the 10 case studies contained in a World Wildlife Fund (WWF) report, issued on July 6, that examines forests, wetlands, steppes, mangroves, and other habitats to determine the underlying causes for biodiversity loss.

  7. Concurrent Structural Fatigue Damage Prognosis Under Uncertainty

    Science.gov (United States)

    2014-04-30

    same experiment is carried on AISI 4340 steel. AISI 4340 steel is a heat treatable, low alloy steel containing nickel, chromium and molybdenum. The...but after the unstable crack growth after the overload, it is 82 83 hard to measure the crack growth per cycle which is smaller than 20...structural and macro materials level. The extension to include material microstructure effect for the fatigue prognosis needs further investigations

  8. Robustness Assessment of Building Structures under Explosion

    Directory of Open Access Journals (Sweden)

    Mark Waggoner

    2012-12-01

    Full Text Available Over the past decade, much research has focused on the behaviour of structures following the failure of a key structural component. Particular attention has been given to sudden column loss, though questions remain as to whether this event-independent scenario is relevant to actual extreme events such as explosion. Few studies have been conducted to assess the performance of floor slabs above a failed column, and the computational tools used have not been validated against experimental results. The research program presented in this paper investigates the adequacy of sudden column loss as an idealisation of local damage caused by realistic explosion events, and extends prior work by combining the development of accurate computational models with large-scale testing of a typical floor system in a prototypical steel-framed structure. The floor system consists of corrugated decking topped by a lightly reinforced concrete slab that is connected to the floor beams through shear studs. The design is consistent with typical building practices in the US. The first test has been completed, and subsequent tests are currently being planned. This paper addresses the importance of robustness design for localized damage and includes a detailed description regarding how the research program advances the current state of knowledge for assessing robustness of compositely constructed steel-framed buildings.

  9. Electronic structure effects of amide group: Vince lactam

    Science.gov (United States)

    Novak, Igor; Kovač, Branka

    2005-03-01

    HeI photoelectron spectrum of 2-azabicyclo[2.2.1]hept-5-en-3-one (Vince lactam) has been measured. The assignment of the spectrum was made by comparison with photoelectron spectra of related compounds and by taking into account the lactam's molecular structure. The analysis of the electronic structure of amide group, in terms of inductive and conjugative effects, is presented on the basis of photoelectron spectroscopic data.

  10. Materials and structures under shock and impact

    CERN Document Server

    Bailly, Patrice

    2013-01-01

    In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site.This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending

  11. Field Test of Driven Pile Group under Lateral Loading

    Science.gov (United States)

    Gorska, Karolina; Rybak, Jaroslaw; Wyjadlowski, Marek

    2017-12-01

    All the geotechnical works need to be tested because the diversity of soil parameters is much higher than in other fields of construction. Horizontal load tests are necessary to determine the lateral capacity of driven piles subject to lateral load. Various load tests were carried out altogether on the test field in Kutno (Poland). While selecting the piles for load tests, different load combinations were taken into account. The piles with diverse length were chosen, on the basis of the previous tests of their length and integrity. The subsoil around the piles consisted of mineral soils: clays and medium compacted sands with the density index ID>0.50. The pile heads were free. The points of support of the “base” to which the dial gauges (displacement sensors) were fastened were located at the distance of 0.7 m from the side surface of the pile loaded laterally. In order to assure the independence of measurement, additional control (verifying) geodetic survey of the displacement of the piles subject to the load tests was carried out (by means of the alignment method). The trial load was imposed in stages by means of a hydraulic jack. The oil pressure in the actuator was corrected by means of a manual pump in order to ensure the constant value of the load in the on-going process of the displacement of the pile under test. On the basis of the obtained results it is possible to verify the numerical simulations of the behaviour of piles loaded by a lateral force.

  12. 76 FR 56099 - Implementation of a Decision Adopted Under the Australia Group (AG) Intersessional Silent...

    Science.gov (United States)

    2011-09-12

    .... 110222155-1110-01] RIN 0694-AF14 Implementation of a Decision Adopted Under the Australia Group (AG... proposal that was discussed at the 2010 Australia Group (AG) Plenary and adopted under the AG... under the Australia Group (AG) intersessional silent approval procedures in November 2010. The AG is a...

  13. Nuclear Structure Group annual progress report June 1974 -May 1975

    International Nuclear Information System (INIS)

    1975-06-01

    This is the first annual progress report of the Nuclear Structure Group of the University of Birmingham. The introduction lists the main fields of study of the Group as: polarisation penomena and optical model studies using 3 He and 4 He probes; photonuclear physics; heavy-ion physics; and K- meson physics. The programme is related to particle accelerators at Birmingham, Oxford, Harwell and the Rutherford Laboratory. The body of the report consists of summaries of 38 experiments undertaken by members of the Group. The third section contains 10 notes on instrumentation topics. Appendices contain lists of (a) personnel, (b) papers published or submitted during the period. (U.K.)

  14. Factor structure underlying components of allostatic load.

    Directory of Open Access Journals (Sweden)

    Jeanne M McCaffery

    Full Text Available Allostatic load is a commonly used metric of health risk based on the hypothesis that recurrent exposure to environmental demands (e.g., stress engenders a progressive dysregulation of multiple physiological systems. Prominent indicators of response to environmental challenges, such as stress-related hormones, sympatho-vagal balance, or inflammatory cytokines, comprise primary allostatic mediators. Secondary mediators reflect ensuing biological alterations that accumulate over time and confer risk for clinical disease but overlap substantially with a second metric of health risk, the metabolic syndrome. Whether allostatic load mediators covary and thus warrant treatment as a unitary construct remains to be established and, in particular, the relation of allostatic load parameters to the metabolic syndrome requires elucidation. Here, we employ confirmatory factor analysis to test: 1 whether a single common factor underlies variation in physiological systems associated with allostatic load; and 2 whether allostatic load parameters continue to load on a single common factor if a second factor representing the metabolic syndrome is also modeled. Participants were 645 adults from Allegheny County, PA (30-54 years old, 82% non-Hispanic white, 52% female who were free of confounding medications. Model fitting supported a single, second-order factor underlying variance in the allostatic load components available in this study (metabolic, inflammatory and vagal measures. Further, this common factor reflecting covariation among allostatic load components persisted when a latent factor representing metabolic syndrome facets was conjointly modeled. Overall, this study provides novel evidence that the modeled allostatic load components do share common variance as hypothesized. Moreover, the common variance suggests the existence of statistical coherence above and beyond that attributable to the metabolic syndrome.

  15. Lie group structures on automorphism groups of real-analytic CR manifolds

    OpenAIRE

    ZAITSEV, DMITRI

    2008-01-01

    PUBLISHED Given any real-analytic CR manifold M, we provide general conditions on M guar- anteeing that the group of all its global real-analytic CR automorphisms AutCR(M) is a Lie group (in an appropriate topology). In particular, we obtain a Lie group structure for AutCR(M) when M is an arbitrary compact real-analytic hypersurface embedded in some Stein manifold. The first author was supported by the Austrian Science Fund FWF, Project P17111 and Project P19667. The second ...

  16. group chemistry of 9-hydroxophenalenone: Syntheses and structural ...

    Indian Academy of Sciences (India)

    Sci. Vol. 126, No. 5, September 2014, pp. 1581–1588. c Indian Academy of Sciences. Main group chemistry of 9-hydroxophenalenone: Syntheses and structural characterization of the alkaline earth and zinc complexes. ARUP MUKHERJEEa, PRINSON P SAMUELb, CAROLA SCHULZKEc and. SWADHIN K MANDALa,∗.

  17. From Wigner Inoenue group contraction to contractions of algebraic structures

    International Nuclear Information System (INIS)

    Gromov, N.A.

    2004-01-01

    The development of the notion of group contraction first introduced by Inoenue and Wigner in 1953 is briefly reviewed. The fundamental role of the idea of degenerate transformations is stressed. The significance of contractions of algebraic structures for exactly solvable problems of mathematical physics is noticed. (author)

  18. Extending a scatterplot for displaying group structure in multivariate ...

    African Journals Online (AJOL)

    ... when regarded as extensions of ordinary scatterplots to describe variation and group structure in multivariate observations, is demonstrated by presenting a case study from the South African wood pulp industry. It is shown how multidimensional standards specified by users of a product may be added to the biplot in the ...

  19. Extending a scatterplot for displaying group structure in multivariate ...

    African Journals Online (AJOL)

    dinary scatterplots to describe variation and group structure in multivariate observations, is demonstrated by presenting a case study from the South African wood pulp industry. It is shown how multidimensional standards specified by users of a product may be added to the biplot in the form of acceptance regions such that ...

  20. Dynamical behavior of price forecasting in structures of group correlations

    Science.gov (United States)

    Lim, Kyuseong; Kim, Soo Yong; Kim, Kyungsik

    2015-07-01

    We investigate the prediction of the future prices from the structures and the networks of the companies in special financial groups. After the financial group network has been constructed from the value of the high cross-correlation, each company in a group is simulated and analyzed how it buys or sells stock is anaylzed and how it makes rational investments is forecasted. In the shortmemory behavior rather than the long-memory behavior, each company among a group can make a rational investment decision by using a stochastic evolution rule in the financial network. In particular, we simulate and analyze the investment situation in connection with the empirical data and the simulated result.

  1. Understanding `galaxy groups' as a unique structure in the universe

    Science.gov (United States)

    Paul, S.; John, R. S.; Gupta, P.; Kumar, H.

    2017-10-01

    'Galaxy groups' have hardly been realized as a separate class of objects with specific characteristics in the structural hierarchy. The presumption that the self-similarity of dark matter structures is a valid prescription for the baryonic universe at all scales has rendered smaller structures undetectable by current observational facilities, leading to lesser dedicated studies on them. Some recent reports that indicate a deviation from LX-T scaling in groups compared to clusters have motivated us to study their physical properties in depth. In this article, we report the extensive study on physical properties of groups in comparison to the clusters through cosmological hydrodynamic plus N-body simulations using enzo 2.2 code. As additional physics, radiative cooling, heating due to supernova and star motions, star formation and stellar feedback have been implemented. We have produced a mock sample of 362 objects with mass ranging from 5 × 1012 M⊙ to 2.5 × 1015 M⊙. Strikingly, we have found that objects with mass below ˜8 × 1013 M⊙ do not follow any of the cluster self-similar laws in hydrostatics, not even in thermal and non-thermal energies. Two distinct scaling laws are observed to be followed with breaks at ˜8 × 1013 M⊙ for mass, ˜1 keV for temperature and ˜1 Mpc for radius. This places groups as a distinct entity in the hierarchical structures, well demarcated from clusters. This study reveals that groups are mostly far away from virialization, suggesting the need for formulating new models for deciphering their physical parameters. They are also shown to have high turbulence and more non-thermal energy stored, indicating better visibility in the non-thermal regime.

  2. Understanding 'Galaxy Groups' as a Unique Structure in the Universe

    Science.gov (United States)

    John, Reju Sam; Paul, Surajit; Gupta, Prateek; Kumar, Harish

    2017-07-01

    'Galaxy groups' have hardly been realized as a separate class of objects with specific characteristics in the structural hierarchy of the universe. The presumption that the self-similarity of dark matter structures is a valid prescription for the baryonic universe also at all scales has rendered smaller structures undetectable by current observational facilities, leading to lesser dedicated studies on them. Some recent reports on deviation of {L_x}-T scaling in groups from that of clusters have motivated us to study their physical properties in depth. In this article, we report the extensive study on physical properties of groups in comparison with clusters through cosmological hydrodynamic plus N-body simulations using ENZO 2.2 code. We have included cooling and heating physics and star formation feedback in the simulation. And produced a mock sample of 362 objects with mass ranging from 5×10^{12} M_{⊙} to 2.5×10^{15} M_{⊙}. Strikingly, we have found that objects with a mass below ˜ 8×10^{13} M_{⊙} do not follow any of the cluster self-similar laws in hydrostatics, not even in thermal and non-thermal regimes. Two distinct scaling laws are observed to be followed with breaks at ˜ 6-8× 10^{13} M_{⊙} for mass, ˜1 keV for temperature and ˜1 Mpc for radius. This places groups as a distinct entity in the hierarchical structures, well demarcated from clusters. This study reveals that groups are mostly far away from virialization, suggesting the need for formulating new models for deciphering their physical parameters. They are also shown to have high turbulence and more non-thermal energy stored, indicating better visibility in the non-thermal regime.

  3. The Effectiveness of Structured Group Education on Ankylosing Spondylitis Patients.

    Science.gov (United States)

    Kasapoglu Aksoy, Meliha; Birtane, Murat; Taştekin, Nurettin; Ekuklu, Galip

    2017-04-01

    Ankylosing spondylitis (AS) is a common inflammatory rheumatic disease that affects the axial skeleton which can lead to structural and functional impairments. It has a negative impact on the person's daily life activities. Early diagnosis, exercise and patient education are factors playing a major role on prognosis. The purpose of the study was to compare the structured theoretical and exercise educational program with routine clinic educational efforts on the parameters of the disorder over a 3 month follow up. This randomized, educational intervention study was performed on 41 AS patients. A 5 day structured education and exercise program was applied to the first group of patients (Group 1) in subgroups consisting 4-5 patients each. Patients had group exercises throughout the education program. The second group followed routine clinical care. The effectiveness of the treatment was assessed by Bath ankylosing spondylitis functional (BASFI), Bath ankylosing spondylitis disease activity (BASDAI), Bath ankylosing spondylitis global (BAS-G), Bath ankylosing spondylitis metrology indices (BASMI), chest expansion, short form-36 (SF-36), ankylosing spondylitis quality of life scale (ASQoL) and laboratory parameters in all patients. Patients were evaluated on initiation and after 3 months. Significant improvements in BASFI, BASDAI and BAS-G, chest expansion, SF-36 and ASQoL indices were observed in Group 1 No difference could be found in BASMI and chest expansion. A structured educational and exercise intervention had a positive effect on the functional status,disease activity, and general well-being and quality of life. It also, shows that education programs should be within the routine treatment program for AS.

  4. Empirical Analysis of Farm Credit Risk under the Structure Model

    Science.gov (United States)

    Yan, Yan

    2009-01-01

    The study measures farm credit risk by using farm records collected by Farm Business Farm Management (FBFM) during the period 1995-2004. The study addresses the following questions: (1) whether farm's financial position is fully described by the structure model, (2) what are the determinants of farm capital structure under the structure model, (3)…

  5. Consensus formation on coevolving networks: groups' formation and structure

    International Nuclear Information System (INIS)

    Kozma, Balazs; Barrat, Alain

    2008-01-01

    We study the effect of adaptivity on a social model of opinion dynamics and consensus formation. We analyse how the adaptivity of the network of contacts between agents to the underlying social dynamics affects the size and topological properties of groups and the convergence time to the stable final state. We find that, while on static networks these properties are determined by percolation phenomena, on adaptive networks the rewiring process leads to different behaviors: adaptive rewiring fosters group formation by enhancing communication between agents of similar opinion, though it also makes possible the division of clusters. We show how the convergence time is determined by the characteristic time of link rearrangement. We finally investigate how the adaptivity yields nontrivial correlations between the internal topology and the size of the groups of agreeing agents

  6. Structural Isosteres of Phosphate Groups in the Protein Data Bank.

    Science.gov (United States)

    Zhang, Yuezhou; Borrel, Alexandre; Ghemtio, Leo; Regad, Leslie; Boije Af Gennäs, Gustav; Camproux, Anne-Claude; Yli-Kauhaluoma, Jari; Xhaard, Henri

    2017-03-27

    We developed a computational workflow to mine the Protein Data Bank for isosteric replacements that exist in different binding site environments but have not necessarily been identified and exploited in compound design. Taking phosphate groups as examples, the workflow was used to construct 157 data sets, each composed of a reference protein complexed with AMP, ADP, ATP, or pyrophosphate as well other ligands. Phosphate binding sites appear to have a high hydration content and large size, resulting in U-shaped bioactive conformations recurrently found across unrelated protein families. A total of 16 413 replacements were extracted, filtered for a significant structural overlap on phosphate groups, and sorted according to their SMILES codes. In addition to the classical isosteres of phosphate, such as carboxylate, sulfone, or sulfonamide, unexpected replacements that do not conserve charge or polarity, such as aryl, aliphatic, or positively charged groups, were found.

  7. Thermal behavior of spatial structures under solar irradiation

    International Nuclear Information System (INIS)

    Liu, Hongbo; Liao, Xiangwei; Chen, Zhihua; Zhang, Qian

    2015-01-01

    The temperature, particularly the non-uniform temperature under solar irradiation, is the main load for large-span steel structures. Due the shortage of in-site temperature test in previous studies, an in-site test was conducted on the large-span steel structures under solar irradiation, which was covered by glass roof and light roof, to gain insight into the temperature distribution of steel members under glass roof or light roof. A numerical method also was presented and verified to forecast the temperature of steel member under glass roof or light roof. Based on the on-site measurement and numerical analyses conducted, the following conclusions were obtained: 1) a remarkable temperature difference exists between the steel member under glass roof and that under light roof, 2) solar irradiation has a significant effect on the temperature distribution and thermal behavior of large-span spatial structures, 3) negative thermal load is the controlling factor for member stress, and the positive thermal load is the controlling factor for nodal displacement. - Highlights: • Temperature was measured for a steel structures under glass roof and light roof. • Temperature simulation method was presented and verified. • The thermal behavior of steel structures under glass or light roof was presented

  8. Multi-family group therapy for adolescent Internet addiction: exploring the underlying mechanisms.

    Science.gov (United States)

    Liu, Qin-Xue; Fang, Xiao-Yi; Yan, Ni; Zhou, Zong-Kui; Yuan, Xiao-Jiao; Lan, Jing; Liu, Chao-Ying

    2015-03-01

    Internet addiction is one of the most common problems among adolescents and effective treatment is needed. This research aims to test the effectiveness and underlying mechanism of multi-family group therapy (MFGT) to reduce Internet addiction among adolescents. A total of 92 participants consisting of 46 adolescents with Internet addiction, aged 12-18years, and 46 their parents, aged 35-46years, were assigned to the experimental group (six-session MFGT intervention) or a waiting-list control. Structured questionnaires were administered at pre-intervention (T1), post-intervention (T2) and a three-month follow-up (T3). There was a significant difference in the decline both in the average score and proportion of adolescents with Internet addiction in MFGT group at post-intervention (MT1=3.40, MT2=2.46, pInternet use was partially explained by the satisfaction of their psychological needs and improved parent-adolescent communication and closeness. The six-session multi-family group therapy was effective in reducing Internet addiction behaviors among adolescents and could be implemented as part of routine primary care clinic services in similar populations. As family support system is critical in maintaining the intervention effect, fostering positive parent-adolescent interaction and addressing adolescents' psychological needs should be included in preventive programs for Internet addiction in the future. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. The Network Structure Underlying the Earth Observation Assessment

    Science.gov (United States)

    Vitkin, S.; Doane, W. E. J.; Mary, J. C.

    2017-12-01

    The Earth Observations Assessment (EOA 2016) is a multiyear project designed to assess the effectiveness of civil earth observation data sources (instruments, sensors, models, etc.) on societal benefit areas (SBAs) for the United States. Subject matter experts (SMEs) provided input and scored how data sources inform products, product groups, key objectives, SBA sub-areas, and SBAs in an attempt to quantify the relationships between data sources and SBAs. The resulting data were processed by Integrated Applications Incorporated (IAI) using MITRE's PALMA software to create normalized relative impact scores for each of these relationships. However, PALMA processing obscures the natural network representation of the data. Any network analysis that might identify patterns of interaction among data sources, products, and SBAs is therefore impossible. Collaborating with IAI, we cleaned and recreated a network from the original dataset. Using R and Python we explore the underlying structure of the network and apply frequent itemset mining algorithms to identify groups of data sources and products that interact. We reveal interesting patterns and relationships in the EOA dataset that were not immediately observable from the EOA 2016 report and provide a basis for further exploration of the EOA network dataset.

  10. Evidence of structural invariance across three groups of Meehlian schizotypes.

    Science.gov (United States)

    Chan, Raymond Ck; Gooding, Diane C; Shi, Hai-Song; Geng, Fu-Lei; Xie, Dong-Jie; Yang, Zhuo-Ya; Liu, Wen-Hua; Wang, Yi; Yan, Chao; Shi, Chuan; Lui, Simon Sy; Cheung, Eric Fc

    2016-01-01

    According to Meehl's model of schizotypy, there is a latent personality organization associated with the diathesis for schizophrenia that can be identified in several ways. We sought to examine the structural invariance of four Chapman psychosis-proneness scales (CPPS) across three groups of putative schizotypes, namely, clinically-, biologically-, and psychometrically-identified schizotypes. We examined the factor structure of the Perceptual Aberration (PER), Magical Ideation (MIS), Revised Social Anhedonia (RSAS), and Revised Physical Anhedonia (RPAS) scales in 196 schizophrenia patients, 197 non-psychotic first-degree relatives, and 1,724 non-clinical young adults. The confirmatory factor analyses indicated that the best-fitting model was one in which there is a two-factor model with negative schizotypy (RSAS and RPAS) and positive schizotypy (PER and MIS). All three samples fit the model well, with Comparative Fit Indices>0.95 and Tucker Lewis Indices>0.90. The root mean square error of approximations were all small (P values⩽0.01). We also observed that for both anhedonia scales, the groups' mean scale scores varied in the hypothesized direction, as predicted by Meehl's model of schizotypy. All three Chinese samples, namely, the patients (clinical schizotypes), relatives (biologically-identified schizotypes), and non-clinical young adults (containing psychometrically-identified schizotypes) showed the same factorial structure. This finding supports the suitability of the CPPS for cross-cultural and/or genetic investigations of schizotypy.

  11. Structure and content of competitive group compositions in sports aerobics

    Directory of Open Access Journals (Sweden)

    Tetiana Moshenska

    2017-02-01

    Full Text Available Purpose: to make the analysis of modern competitive group compositions in sports aerobics. Material & Methods: pedagogical, sociological and methods of mathematical statistics were used. 10 coaches took part in the experimental part; analysis of protocols and video records of competitions of the aged category of children of 9–11 years old, who perform in the nomination of triplets and quintuples (group exercises, is carried out. Results: the content of competitive compositions and the allocated indicators are studied which defined it. Conclusions: the basic structural elements, which characterize competitive compositions, are allocated. Their components, quantity and time of performance are defined. It is established that variety of aerobic contents, spaces, and means of registration, musical compliance and logicality of creation of the whole competitive composition at high quality of performance characterizes teams – winners.

  12. On the algebraic structure of differential calculus on quantum groups

    International Nuclear Information System (INIS)

    Rad'ko, O.V.; Vladimirov, A.A.

    1997-01-01

    Intrinsic Hopf algebra structure of the Woronowicz differential complex is shown to generate quite naturally a bicovariant algebra of four basic objects within a differential calculus on quantum groups - coordinate functions, differential forms, Lie derivatives, and inner derivatives - as the cross-product algebra of two mutually dual graded Hopf algebras. This construction, properly taking into account Hopf-algebraic properties of Woronowicz's bicovariant calculus, provides a direct proof of the Cartan identity and of many other useful relations. A detailed comparison with other approaches is also given

  13. 20 CFR 229.49 - Adjustment of benefits under family maximum for change in family group.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Adjustment of benefits under family maximum for change in family group. 229.49 Section 229.49 Employees' Benefits RAILROAD RETIREMENT BOARD... Overall Minimum Rate § 229.49 Adjustment of benefits under family maximum for change in family group. (a...

  14. Factors limiting the operation of structures under high gradient

    International Nuclear Information System (INIS)

    Schriber, S.O.

    1986-01-01

    Factors limiting the operation of rf structures under high-gradient conditions are described. Included are recent rf measurements at laboratories in Europe, Asia, and North America and how these measurements relate to earlier data as exemplified by the use of the Kilpatrick criterion (Kp). Operation limitations will cover mechanical, geometry, thermal, and surface constraints and the associated impact on structure design, fabrication, and material selection. Generally, structures operating continuous wave (100% duty factor) appear to be limited to peak surface fields at about twice the Kilpatrick limit, whereas pulsed structures operating with pulse lengths less than a millisecond can attain peak surface fields five times the Kilpatrick limit

  15. Minority group status and healthful aging: social structure still matters.

    Science.gov (United States)

    Angel, Jacqueline L; Angel, Ronald J

    2006-07-01

    During the last 4 decades, a rapid increase has occurred in the number of survey-based and epidemiological studies of the health profiles of adults in general and of the causes of disparities between majority and minority Americans in particular. According to these studies, healthful aging consists of the absence of disease, or at least of the most serious preventable diseases and their consequences, and findings consistently reveal serious African American and Hispanic disadvantages in terms of healthful aging. We (1) briefly review conceptual and operational definitions of race and Hispanic ethnicity, (2) summarize how ethnicity-based differentials in health are related to social structures, and (3) emphasize the importance of attention to the economic, political, and institutional factors that perpetuate poverty and undermine healthful aging among certain groups.

  16. Numerical Analysis of Vibrations of Structures under Moving Inertial Load

    CERN Document Server

    Bajer, Czeslaw I

    2012-01-01

    Moving inertial loads are applied to structures in civil engineering, robotics, and mechanical engineering. Some fundamental books exist, as well as thousands of research papers. Well known is the book by L. Frýba, Vibrations of Solids and Structures Under Moving Loads, which describes almost all problems concerning non-inertial loads. This book presents broad description of numerical tools successfully applied to structural dynamic analysis. Physically we deal with non-conservative systems. The discrete approach formulated with the use of the classical finite element method results in elemental matrices, which can be directly added to global structure matrices. A more general approach is carried out with the space-time finite element method. In such a case, a trajectory of the moving concentrated parameter in space and time can be simply defined. We consider structures described by pure hyperbolic differential equations such as strings and structures described by hyperbolic-parabolic differential equations ...

  17. Introductory group theory and its application to molecular structure

    CERN Document Server

    Ferraro, John R

    1975-01-01

    The success of the first edition of this book has encouraged us to revise and update it. In the second edition we have attempted to further clarify por­ tions of the text in reference to point symmetry, keeping certain sections and removing others. The ever-expanding interest in solids necessitates some discussion on space symmetry. In this edition we have expanded the discus­ sion on point symmetry to include space symmetry. The selection rules in­ clude space group selection rules (for k = 0). Numerous examples are pro­ vided to acquaint the reader with the procedure necessary to accomplish this. Recent examples from the literature are given to illustrate the use of group theory in the interpretation of molecular spectra and in the determination of molecular structure. The text is intended for scientists and students with only a limited theoretical background in spectroscopy. For this reason we have presented detailed procedures for carrying out the selection rules and normal coor­ dinate treatment of ...

  18. 76 FR 33029 - Agency Information Collection (Disability Benefits Questionnaires-Group 1) Under OMB Review

    Science.gov (United States)

    2011-06-07

    ... AFFAIRS Agency Information Collection (Disability Benefits Questionnaires--Group 1) Under OMB Review AGENCY: Veterans Benefits Administration, Department of Veterans Affairs. ACTION: Notice. SUMMARY: In... the Veterans Benefits Administration (VBA), Department of Veterans Affairs, will submit the collection...

  19. Application of the renormalization group to the study of structure function in the deep inelastic scattering

    International Nuclear Information System (INIS)

    Dias, S.A.

    1985-01-01

    The transformation law of truncated pertubation theory observables under changes of renormalization scheme is deduced. Based on this, a criticism of the calculus of the moments of structure functions in deep inelastic scattering, obtaining that the A 2 coefficient not renormalization group invariant is done. The PMS criterion is used to optimize the perturbative productions of the moments, truncated to 2nd order. (author) [pt

  20. Characterizing Thematized Derivative Schema by the Underlying Emergent Structures

    Science.gov (United States)

    Garcia, Mercedes; Llinares, Salvador; Sanchez-Matamoros, Gloria

    2011-01-01

    This paper reports on different underlying structures of the derivative schema of three undergraduate students that were considered to be at the trans level of development of the derivative schema (action-process-object-schema). The derivative schema is characterized in terms of the students' ability to explicitly transfer the relationship between…

  1. Colloidal hard dumbbells under gravity: structure and crystallization

    NARCIS (Netherlands)

    Marechal, M.A.T.; Dijkstra, M.

    2011-01-01

    We study the structure and phase behavior of hard dumbbells under gravity. The fluid shows layering near the wall, where subsequent layers of dumbbells align alternatingly parallel or perpendicular to the wall. We observe coexistence of a fluid with a plastic crystal (PC) and an aligned crystal

  2. The Fatigue Behavior of Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    2009-01-01

    Fatigue damage accumulation in steel structures under random loading has been studied in a number of investigations at the Technical University of Denmark. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part...

  3. The Fatigue Behavior of Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    2008-01-01

    Fatigue damage accumulation in steel structures under random loading has been studied in a number of investigations at the Technical University of Denmark. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part...

  4. Structural composite panel performance under long-term load

    Science.gov (United States)

    Theodore L. Laufenberg

    1988-01-01

    Information on the performance of wood-based structural composite panels under long-term load is currently needed to permit their use in engineered assemblies and systems. A broad assessment of the time-dependent properties of panels is critical for creating databases and models of the creep-rupture phenomenon that lead to reliability-based design procedures. This...

  5. Comparing Indirect Effects in Different Groups in Single-Group and Multi-Group Structural Equation Models

    Directory of Open Access Journals (Sweden)

    Ehri Ryu

    2017-05-01

    Full Text Available In this article, we evaluated the performance of statistical methods in single-group and multi-group analysis approaches for testing group difference in indirect effects and for testing simple indirect effects in each group. We also investigated whether the performance of the methods in the single-group approach was affected when the assumption of equal variance was not satisfied. The assumption was critical for the performance of the two methods in the single-group analysis: the method using a product term for testing the group difference in a single path coefficient, and the Wald test for testing the group difference in the indirect effect. Bootstrap confidence intervals in the single-group approach and all methods in the multi-group approach were not affected by the violation of the assumption. We compared the performance of the methods and provided recommendations.

  6. Effect of group walking traffic on dynamic properties of pedestrian structures

    Science.gov (United States)

    Shahabpoor, E.; Pavic, A.; Racic, V.; Zivanovic, S.

    2017-01-01

    The increasing number of reported vibration serviceability problems in newly built pedestrian structures, such as footbridges and floors, under walking load has attracted considerable attention in the civil engineering community over the past two decades. The key design challenges are: the inter- and intra-subject variability of walking people, the unknown mechanisms of their interaction with the vibrating walking surfaces and the synchronisation between individuals in a group. Ignoring all or some of these factors makes the current design methods an inconsistent approximation of reality. This often leads to considerable over- or under-estimation of the structural response, yielding an unreliable assessment of vibration performance. Changes to the dynamic properties of an empty structure due to the presence of stationary people have been studied extensively over the past two decades. The understanding of the similar effect of walking people on laterally swaying bridges has improved tremendously in the past decade, due to considerable research prompted by the Millennium Bridge problem. However, there is currently a gap in knowledge about how moving pedestrians affect the dynamic properties of vertically vibrating structures. The key reason for this gap is the scarcity of credible experimental data pertinent to moving pedestrians on vertically vibrating structures, especially for multi-pedestrian traffic. This paper addresses this problem by studying the dynamic properties of the combined human-structure system, i.e. occupied structure damping ratio, natural frequency and modal mass. This was achieved using a comprehensive set of frequency response function records, measured on a full-scale test structure, which was occupied by various numbers of moving pedestrians under different walking scenarios. Contrary to expectations, it was found that the natural frequency of the joint moving human-structure system was higher than that of the empty structure, while it was

  7. Design of mild steel structures under unequal cyclic loads

    International Nuclear Information System (INIS)

    In this paper a method is proposed to investigate the behavior and life of structural components under unequal cyclic loading conditions. Appropriate cyclic moment-curvature relations and life information, in the form of life versus extreme fiber strain, are developed from tests on beams under pure bending conditions. Theoretical predictions of behavior are based on structural geometry and the cyclic moment-curvature relations used in association with the simple curvature-area method. Structural life is also predicted using the life information developed and the theoretical strain history at the critical section in conjunction with a linear damage summation criterion. Theoretical predictions of behavior and life compare reasonably well with the experiments. Based on this study, a design procedure is proposed for mild steel components subjected to unequal cyclic loading conditions. The loads on the tested components were such that they failed due to low cyclic fatigue (i.e., at less than 10 5 cycles)

  8. Nonplanar Organic Sensitizers Featuring a Tetraphenylethene Structure and Double Electron-Withdrawing Anchoring Groups.

    Science.gov (United States)

    Zhang, Fangshuai; Fan, Jie; Yu, Huijuan; Ke, Zhuofeng; Nie, Changming; Kuang, Daibin; Shao, Guang; Su, Chengyong

    2015-09-18

    Two metal-free organic sensitizers containing two N,N-diethylaniline (DEA) moieties and a twisted 1,1,2,2-tetraphenylethene (TPE) structure, dye SD with one anchoring group and dye DD with two anchoring groups, were synthesized and applied in dye-sensitized solar cells (DSSCs). The introduction of a nonplanar TPE structure was used to form a series of propeller-like structures and reduce the tendency of dyes to randomly aggregate on TiO2 surface, but without importing an aggregation-induced emission (AIE) property. The thermal stabilities, UV-vis absorption spectra, electrochemical properties, and photovoltaic parameters of DSSCs with these two dyes were systematically studied and compared with each other. The overall conversion efficiencies (η) of 4.56% for dye SD and 6.08% for dye DD were obtained under AM 1.5 G irradiation.

  9. Quantum group structure and local fields in the algebraic approach to 2D gravity

    CERN Document Server

    Schnittger, Jens

    1994-01-01

    This review contains a summary of work by J.-L. Gervais and the author on the operator approach to 2d gravity. Special emphasis is placed on the construction of local observables -the Liouville exponentials and the Liouville field itself - and the underlying algebra of chiral vertex operators. The double quantum group structure arising from the presence of two screening charges is discussed and the generalized algebra and field operators are derived. In the last part, we show that our construction gives rise to a natural definition of a quantum tau function, which is a noncommutative version of the classical group-theoretic representation of the Liouville fields by Leznov and Saveliev.

  10. Modulation of endothelial glycocalyx structure under inflammatory conditions.

    Science.gov (United States)

    Kolářová, Hana; Ambrůzová, Barbora; Svihálková Šindlerová, Lenka; Klinke, Anna; Kubala, Lukáš

    2014-01-01

    The glycocalyx of the endothelium is an intravascular compartment that creates a barrier between circulating blood and the vessel wall. The glycocalyx is suggested to play an important role in numerous physiological processes including the regulation of vascular permeability, the prevention of the margination of blood cells to the vessel wall, and the transmission of shear stress. Various theoretical models and experimental approaches provide data about changes to the structure and functions of the glycocalyx under various types of inflammatory conditions. These alterations are suggested to promote inflammatory processes in vessels and contribute to the pathogenesis of number of diseases. In this review we summarize current knowledge about the modulation of the glycocalyx under inflammatory conditions and the consequences for the course of inflammation in vessels. The structure and functions of endothelial glycocalyx are briefly discussed in the context of methodological approaches regarding the determination of endothelial glycocalyx and the uncertainty and challenges involved in glycocalyx structure determination. In addition, the modulation of glycocalyx structure under inflammatory conditions and the possible consequences for pathogenesis of selected diseases and medical conditions (in particular, diabetes, atherosclerosis, ischemia/reperfusion, and sepsis) are summarized. Finally, therapeutic strategies to ameliorate glycocalyx dysfunction suggested by various authors are discussed.

  11. Modulation of Endothelial Glycocalyx Structure under Inflammatory Conditions

    Directory of Open Access Journals (Sweden)

    Hana Kolářová

    2014-01-01

    Full Text Available The glycocalyx of the endothelium is an intravascular compartment that creates a barrier between circulating blood and the vessel wall. The glycocalyx is suggested to play an important role in numerous physiological processes including the regulation of vascular permeability, the prevention of the margination of blood cells to the vessel wall, and the transmission of shear stress. Various theoretical models and experimental approaches provide data about changes to the structure and functions of the glycocalyx under various types of inflammatory conditions. These alterations are suggested to promote inflammatory processes in vessels and contribute to the pathogenesis of number of diseases. In this review we summarize current knowledge about the modulation of the glycocalyx under inflammatory conditions and the consequences for the course of inflammation in vessels. The structure and functions of endothelial glycocalyx are briefly discussed in the context of methodological approaches regarding the determination of endothelial glycocalyx and the uncertainty and challenges involved in glycocalyx structure determination. In addition, the modulation of glycocalyx structure under inflammatory conditions and the possible consequences for pathogenesis of selected diseases and medical conditions (in particular, diabetes, atherosclerosis, ischemia/reperfusion, and sepsis are summarized. Finally, therapeutic strategies to ameliorate glycocalyx dysfunction suggested by various authors are discussed.

  12. Safety margins of containment structures under impulsive loading

    International Nuclear Information System (INIS)

    Lu, S.C.H.

    1978-01-01

    Containment structures for nuclear power plants are designed to a large extent to satisfy the various stress limits specified by ASME Boiler and Pressure Vessel Code. For short-duration impulsive loads, the common practice of meeting the Code stress limits based on a quasi-static approach is a poor measure of the reserve load-carrying capacity of a structure and always results in a conservative design with a greater than desired margin of safety. There are situations, however, where one might wish to quantify this additional conservatism to avoid excessive or unnecessary field modification. Typical examples were found in re-evaluation studies of MARK I Boiling Water Reactor containment structures under the hydrodynamic loads expected during a postulated loss-of-coolant accident. The paper is based on the results of a plane strain, large displacement, elastic-plastic, finite-element analysis of a thin cylindrical shell subjected to external pressure pulses. An analytical procedure is presented for estimating the ultimate load capacity of the thin shell structure and, subsequently, for quantifying the design margins of safety for the type of loads under consideration. For defining failure of structures, a finite strain failure criterion is derived that accounts for multiaxiality effects

  13. Effect of support conditions on structural response under dynamic loading

    International Nuclear Information System (INIS)

    Akram, T.; Memon, S.A.

    2008-01-01

    In design practice, dynamic structural analysis is carried out with base of structure considered as fixed; this means that foundation is placed on rock like soil material. While conducting this type of analyses the role of foundation and soil behaviour is totally neglected. The actions in members and loads transferred at foundation level obtained in this manner do not depict the true structural behaviour. FEM (Finite Element Methods) analysis where both superstructure and foundation soil are coupled together is quite complicated and expensive for design environments. A simplified model is required to depict dynamic response of structures with foundations based on flexible soils. The primary purpose of this research is to compare the superstructure dynamic responses of structural systems with fixed base to that of simple soil model base. The selected simple soil model is to be suitable for use in a design environment to give more realistic results. For this purpose building models are idealized with various heights and structural systems in both 2D (Two Dimensional) and 3D (Three Dimensional) space. These models are then provided with visco-elastic supports representing three soil bearing capacities and the analysis results are compared to that of fixed supports models. The results indicate that fixed support system underestimates natural time period of the structures. Dynamic behavior and force response of visco-elastic support is different from fixed support model. Fixed support models result in over designed base columns and under designed beams. (author)

  14. Generalized Minimum Variance Control for MDOF Structures under Earthquake Excitation

    Directory of Open Access Journals (Sweden)

    Lakhdar Guenfaf

    2016-01-01

    Full Text Available Control of a multi-degree-of-freedom structural system under earthquake excitation is investigated in this paper. The control approach based on the Generalized Minimum Variance (GMV algorithm is developed and presented. Our approach is a generalization to multivariable systems of the GMV strategy designed initially for single-input-single-output (SISO systems. Kanai-Tajimi and Clough-Penzien models are used to generate the seismic excitations. Those models are calculated using the specific soil parameters. Simulation tests using a 3DOF structure are performed and show the effectiveness of the control method.

  15. Structural Evaluation on HIC Transport Packaging under Accident Conditions

    International Nuclear Information System (INIS)

    Chung, Sung Hwan; Kim, Duck Hoi; Jung, Jin Se; Yang, Ke Hyung; Lee, Heung Young

    2005-01-01

    HIC transport packaging to transport a high integrity container(HIC) containing dry spent resin generated from nuclear power plants is to comply with the regulatory requirements of Korea and IAEA for Type B packaging due to the high radioactivity of the content, and to maintain the structural integrity under normal and accident conditions. It must withstand 9 m free drop impact onto an unyielding surface and 1 m drop impact onto a mild steel bar in a position causing maximum damage. For the conceptual design of a cylindrical HIC transport package, three dimensional dynamic structural analysis to ensure that the integrity of the package is maintained under all credible loads for 9 m free drop and 1 m puncture conditions were carried out using ABAQUS code.

  16. Portfolio optimization with structured products under return constraint

    Directory of Open Access Journals (Sweden)

    Baweja Meena

    2015-01-01

    Full Text Available A new approach for optimizing risk in a portfolio of financial instruments involving structured products is presented. This paper deals with a portfolio selection model which uses optimization methodology to minimize conditional Value-at-Risk (CVaR under return constraint. It focuses on minimizing CVaR rather than on minimizing value-at-Risk VaR, as portfolios with low CVaR necessarily have low VaR as well. We consider a simple investment problem where besides stocks and bonds, the investor can also include structured products into the investment portfolio. Due to possible intermediate payments from structured product, we have to deal with a re-investment problem modeled as a linear optimization problem.

  17. Structural pounding of concrete frame structure with masonry infill wall under seismic loading

    Science.gov (United States)

    Ismail, Rozaina; Hasnan, Mohd Hafizudin; Shamsudin, Nurhanis

    2017-10-01

    Structural pounding is additional problem than the other harmful damage that may occurs due to the earthquake vibrations. A lot of study has been made by past researcher but most of them did not include the walls. The infill masonry walls are rarely involved analysis of structural systems but it does contribute to earthquake response of the structures. In this research, a comparison between adjacent building of 10-storey and 7-storey concrete frame structure without of masonry infill walls and the same dynamic properties of buildings. The diagonal strut approach is adopted for modeling masonry infill walls. This research also focused on finding critical building separation in order to prevent the adjacent structures from pounding. LUSAS FEA v14.03 software has been used for modeling analyzing the behavior of structures due to seismic loading and the displacement each floor of the building has been taken in order to determine the critical separation distance between the buildings. From the analysis that has been done, it is found that masonry infill walls do affect the structures behavior under seismic load. Structures without masonry infill walls needs more distance between the structures to prevent structural pounding due to higher displacement of the buildings when it sways under seismic load compared to structures with masonry infill walls. This shows that contribution of masonry infill walls to the analysis of structures cannot be neglected.

  18. Optimal Tuned Mass Damper for Nonlinear Structure under Different Earthquakes

    Directory of Open Access Journals (Sweden)

    K. Shakeri

    2015-07-01

    Full Text Available Since there is no closed-form formula for designing TMD (Tuned Mass Damper for nonlinear structures, some researchers have proposed numerical optimization procedures such as a genetic algorithm to obtain the optimal values of TMD parameters for nonlinear structures. These methods are based on determining the optimal values of TMD parameters to minimize the maximum response (e.g. inter story drift of the controlled structure subjected to a specific earthquake record. Therefore, the performance of TMD that has been designed using a specific record strongly depends on the characteristics of the earthquake record. By changing the characteristics of the input earthquake record, the efficiency of TMD is changed and in some cases, it is possible that the response of the controlled structure is increased. To overcome the shortcomings of the previous researches, in this paper, an efficient method for designing optimal TMD on nonlinear structures is proposed, in which the effect of different ground motion records is considered in the design procedure. In the proposed method, the optimal value of the TMD parameters are determined so that the average maximum response (e.g. inter story drift resulting from different records in the controlled structure is minimized. To illustrate the procedure of the propose method, the method is used to design optimal TMD for a sample structure. The results of numerical simulations show that the average maximum response of controlled structure resulting from different records is reduced significantly. Hence, it can be concluded that the proposed method for designing optimal TMD under different earthquakes is effective.

  19. The structure of ethnic attitudes: the effects of target group, region, gender, and national identity.

    Science.gov (United States)

    Verkuyten, M

    1997-08-01

    The present study was an assessment of attitudes of 410 ethnically Dutch adolescents toward three ethnic minority groups living in the Netherlands. Stereotypes, symbolic beliefs, affective associations, and the evaluation of possible interactions were used to predict the global evaluation of ethnic outgroups and accounted for much of the variance in ethnic attitudes. The relative importance of the four predictors varied by target group and location. Gender differences were found in the structure of attitudes; symbolic beliefs played a greater role in the attitudes of boys, whereas emotions played a more central role in the attitudes of girls. The evaluation of Dutch identity was related to the favorability of ethnic attitudes and also to the underlying structure. Respondents with a positive national identity had less favorable ethnic attitudes, and emotions were more predictive of their attitudes, whereas symbolic beliefs were most predictive among respondents with a less positive national identity.

  20. Crystalline structures of poly(L-lactide) formed under pressure and structure transitions with heating

    DEFF Research Database (Denmark)

    Huang, Shaoyong; Li, Hongfei; Yu, Donghong

    2013-01-01

    The isothermally crystallized poly(L-lactide) (PLLA) samples were obtained at 135 °C under pressures (Pc) ranging from 1 bar to 2.5 kbar. The crystalline structures, the structure transition, and thermal properties of the prepared samples were investigated by wide-angle X-ray diffraction (WAXD...

  1. Pericarp structure of the Caryopteris group (Lamiaceae subfam. Ajugoideae)

    DEFF Research Database (Denmark)

    Ryding, Per Olof

    2009-01-01

    Pericarp and seed structure was investigated in 13 out of the 16 species of the old Caryopteris s.lat. and in a few species of  the related Rubiteucris, Amethystea, Trichostema and Ajuga. The pericarp structure was found to be very variable, and the variation largely matches the most recent class...

  2. Can we separate verbs from their argument structure? A group study in aphasia.

    Science.gov (United States)

    Caley, Sarah; Whitworth, Anne; Claessen, Mary

    2017-01-01

    Given the integral role that verbs play in sentence production, understanding verb deficits is critical to clinical practice. Difficulties in sentence production are often directly related to an inability to retrieve argument structure information which, according to most theoretical accounts, is specified at a lexical level as part of the semantic representation of the verb. The presence of an argument complexity effect when retrieving verbs in isolation, i.e. increased difficulty with increasing number of arguments required by the verb, is considered evidence of the integral link between verbs and the ensuing structure. Recent reports, however, of relatively intact verb retrieval and impaired argument structure suggest that difficulties with verbs and argument structure may not always co-occur. One explanation for this is that lexical-syntactic information may be stored separately to lexical-semantic information at the lemma level and then differentially impaired. To determine whether the presence of difficulties creating argument structure in a group of people with aphasia with verb-retrieval deficits consistently aligned with the underlying nature of their impairment, where semantic involvement resulted in argument structure difficulties and post-semantic impairment resulted in intact argument structure. This would provide evidence either to support or to challenge the view that argument structure is lexically specified. The presence of an argument complexity effect within the participants' single verb naming was also investigated to examine the relationship between verb argument information and any subsequent difficulties creating argument structure for sentence production. Verb retrieval and argument structure production were investigated in 12 people with aphasia with verb-retrieval deficits on single-word and sentence-production measures. Eight of the 12 participants presented with a semantic verb deficit (five semantic and three mixed semantic and

  3. Parallel Evolution of Chromatin Structure Underlying Metabolic Adaptation.

    Science.gov (United States)

    Cheng, Jian; Guo, Xiaoxian; Cai, Pengli; Cheng, Xiaozhi; Piškur, Jure; Ma, Yanhe; Jiang, Huifeng; Gu, Zhenglong

    2017-11-01

    Parallel evolution occurs when a similar trait emerges in independent evolutionary lineages. Although changes in protein coding and gene transcription have been investigated as underlying mechanisms for parallel evolution, parallel changes in chromatin structure have never been reported. Here, Saccharomyces cerevisiae and a distantly related yeast species, Dekkera bruxellensis, are investigated because both species have independently evolved the capacity of aerobic fermentation. By profiling and comparing genome sequences, transcriptomic landscapes, and chromatin structures, we revealed that parallel changes in nucleosome occupancy in the promoter regions of mitochondria-localized genes led to concerted suppression of mitochondrial functions by glucose, which can explain the metabolic convergence in these two independent yeast species. Further investigation indicated that similar mutational processes in the promoter regions of these genes in the two independent evolutionary lineages underlay the parallel changes in chromatin structure. Our results indicate that, despite several hundred million years of separation, parallel changes in chromatin structure, can be an important adaptation mechanism for different organisms. Due to the important role of chromatin structure changes in regulating gene expression and organism phenotypes, the novel mechanism revealed in this study could be a general phenomenon contributing to parallel adaptation in nature. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Fatigue life prediction of mechanical structures under stochastic loading

    Directory of Open Access Journals (Sweden)

    Leitner Bohuš

    2018-01-01

    Full Text Available Problems of fatigue life prediction of materials and structures are discussed in the paper. Service loading is assumed as a continuous loading process with possible discontinuous events, which are caused by various operating conditions. The damage in a material is due to a cumulative degradation process. The damaging process is then represented either by rain-flow matrices or by a fatigue damage function which is derived using some hypothesis of a fatigue failure criterion. Presented theoretical procedure enables a very effective estimation of a service life and/or reliable evaluation of residual life of any structures under various types of loading and environmental conditions. This approach creates a good basis for powerful expert systems in structural and mechanical engineering. The aim of the paper is to present briefly some results of analysis of load-bearing steel structure loads of special railway crane PKP 25/20i which was utilized in some specific ad relatively hard operating conditions. Virtual models of the structure were being used in an analysis of acting working dynamics loads influence to be able to forecast fatigue life of load-bearing of the crane jib.

  5. Resolving Microzooplankton Functional Groups In A Size-Structured Planktonic Model

    Science.gov (United States)

    Taniguchi, D.; Dutkiewicz, S.; Follows, M. J.; Jahn, O.; Menden-Deuer, S.

    2016-02-01

    Microzooplankton are important marine grazers, often consuming a large fraction of primary productivity. They consist of a great diversity of organisms with different behaviors, characteristics, and rates. This functional diversity, and its consequences, are not currently reflected in large-scale ocean ecological simulations. How should these organisms be represented, and what are the implications for their biogeography? We develop a size-structured, trait-based model to characterize a diversity of microzooplankton functional groups. We compile and examine size-based laboratory data on the traits, revealing some patterns with size and functional group that we interpret with mechanistic theory. Fitting the model to the data provides parameterizations of key rates and properties, which we employ in a numerical ocean model. The diversity of grazing preference, rates, and trophic strategies enables the coexistence of different functional groups of micro-grazers under various environmental conditions, and the model produces testable predictions of the biogeography.

  6. Advanced density matrix renormalization group method for nuclear structure calculations

    Czech Academy of Sciences Publication Activity Database

    Legeza, Ö.; Veis, Libor; Poves, A.; Dukelsky, J.

    2015-01-01

    Roč. 92, č. 5 (2015), 051303 ISSN 0556-2813 Institutional support: RVO:61388955 Keywords : INITIO QUANTUM-CHEMISTRY * GROUP ALGORITHM * SHELL-MODEL Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.146, year: 2015

  7. Consolidated techniques for groups of enterprises with complex structure

    Directory of Open Access Journals (Sweden)

    Cristina Ciuraru-Andrica

    2009-12-01

    Full Text Available The preparation and disclosure of the financial statements of a group of enterprises involves some consolidation techniques. The Literature presents many techniques, but in practice are used two of them. They will be described first of all in a particular manner and after that in a comparative one. The group of entities can choose one of these techniques, the final result (the consolidated financial statements being the same, whatever the option.

  8. Structural Changes of International Trade Flows under the Impact of Globalization

    Directory of Open Access Journals (Sweden)

    Anca Dachin

    2006-08-01

    Full Text Available Structural changes of international trade flows indicate modifications in competitiveness of countries, in terms of production, technological upgrading and exports under the pressure of globalization. The paper aims to point out sources of competitive advantages especially in manufacturing exports of different groups of countries. The focus is on the shifts in the structure of manufacturing in the European Union and their effects on international rankings in export performances. An important issue refers to the opportunities given by the enlargement of the European Union and their impact on EU trade structures.

  9. CARIBBEAN OFFSHORE CORPORATE STRUCTURES UNDER A SWOT ANALYSIS

    Directory of Open Access Journals (Sweden)

    Ana-Maria GEAMÃNU

    2015-04-01

    Full Text Available Tax havens have long been under the attention of numerous Governments and International Organizations which triggered the concern of an uneven playing field in the taxation area. As a result numerous amendments have been made to both their commercial and tax legislations in order to be in line with the internationally agreed tax standards. The aim of this article is to conduct a SWOT analysis on the offshore corporate structures found in the Caribbean landscape. Based on a selection process of the most commonly recognized tax havens in the Caribbean region and an analysis of their offshore companies at the level of incorporation, administration, activities conducted and costs, a set of frequently met characteristics have been identified which stand at the basis of the SWOT analysis. The results stand to present a comprehensive four dimension framework of the offshore corporate structures in regards to their strengths, weaknesses, opportunities and threats.

  10. Capital Structure Arbitrage under a Risk-Neutral Calibration

    Directory of Open Access Journals (Sweden)

    Peter J. Zeitsch

    2017-01-01

    Full Text Available By reinterpreting the calibration of structural models, a reassessment of the importance of the input variables is undertaken. The analysis shows that volatility is the key parameter to any calibration exercise, by several orders of magnitude. To maximize the sensitivity to volatility, a simple formulation of Merton’s model is proposed that employs deep out-of-the-money option implied volatilities. The methodology also eliminates the use of historic data to specify the default barrier, thereby leading to a full risk-neutral calibration. Subsequently, a new technique for identifying and hedging capital structure arbitrage opportunities is illustrated. The approach seeks to hedge the volatility risk, or vega, as opposed to the exposure from the underlying equity itself, or delta. The results question the efficacy of the common arbitrage strategy of only executing the delta hedge.

  11. Structural characterization of lipidic systems under nonequilibrium conditions

    DEFF Research Database (Denmark)

    Yaghmur, Anan; Rappolt, Michael

    2012-01-01

    manipulation techniques including, for instance, stop-flow mixing or rapid temperature-jump perturbation is given. Second, our recent synchrotron SAXS findings on the dynamic structural response of gold nanoparticle-loaded vesicles upon exposure to an ultraviolet light source, the impact of rapidly mixing...... and the possible formation of intermediate states in the millisecond to second range. The need for investigating self-assembled systems, mainly stimuli-responsive drug nanocarriers, under nonequilibrium conditions is discussed. For pharmaceutically relevant applications, it is essential to combine...

  12. Structural Behavior of SC and RC Panels under Impact Loading

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyuk-Kee; Kim, Seung-Eock [Sejong University, Seoul (Korea, Republic of)

    2015-05-15

    NPP structures have been generally constructed using reinforced concrete (RC) structures. In recent studies, however, it has been confirmed that a steel-plate concrete (SC) structures has a much better impact resistance than an RC structure. In this paper, the impact resistance of SC and RC panels is evaluated using the commercial software LS-DYNA. To verify finite element (FE) models, the analysis results for SC and half steel-plate concrete panels under impact loading are compared with the test results conducted in other research. The impact analysis according to the different steel ratios with four different concrete thicknesses is performed in order to compare the impact resistance of SC and RC panels. To compare the impact resistance of SC and RC panels, the impact analysis was performed according to the different steel ratios with four different concrete thicknesses. Based on this study, the following conclusions have been obtained: (1) The rear face steel plate of SC panel plays more important role than the rear rebar of RC panel in preventing perforation. (2) When the perforation failure occurs, RC panel is more effective than SC panel to reduce the velocity of the missile.

  13. On structural design optimization under uncertainty and risk

    International Nuclear Information System (INIS)

    Teofilo Beck, Andre; Santana Gomes, Wellison Jose de

    2010-01-01

    In this paper, the effects of uncertainty and risk on structural design optimization are investigated, by comparing results of Deterministic Design Optimization (DDO), Reliability-based Design Optimization (RBDO) and Reliability-based Risk Optimization (RBRO). DDO yields a structural topology (or shape) which is optimum in terms of mechanics, but does not explicitly address parameter uncertainties and their effects on structural safety. RBDO properly models safety-under-uncertainty, allowing the optimum structure to maintain an acceptable level of safety. Results, however, are dependent on the failure probability used as constraint. Risk optimization (RBRO) increases the scope of the problem, by addressing the compromising goals of economy and safety. This is accomplished by quantifying the costs associated to construction, operation and maintenance, as well as the monetary consequences of failure. RBRO yields the optimum topology and the optimum point of balance between economy and safety. Results are compared for some example problems. The broader RBRO solution is found first, and optimum results are used as constraints in DDO and RBDO. Results show that even when the optimum safety coefficients are used as constraint in DDO, the formulation leads to optimum configurations which respect these design constraints, reduce manufacturing costs but increase total expected costs (including expected cost of failure). If the (optimum) system failure probability is used as constraint in RBDO, the optimum solution reduces manufacturing costs, but by increasing total expected costs. This happens when the costs associated to different failure modes are distinct.

  14. Topological spin-singlet superconductors with underlying sublattice structure

    Science.gov (United States)

    Dutreix, C.

    2017-07-01

    Majorana boundary quasiparticles may naturally emerge in a spin-singlet superconductor with Rashba spin-orbit interactions when a Zeeman magnetic field breaks time-reversal symmetry. Their existence and robustness against adiabatic changes is deeply related, via a bulk-edge correspondence, to topological properties of the band structure. The present paper shows that the spin-orbit may be responsible for topological transitions when the superconducting system has an underlying sublattice structure, as it appears in a dimerized Peierls chain, graphene, and phosphorene. These systems, which belong to the Bogoliubov-de Gennes class D, are found to have an extra symmetry that plays the role of the parity. It enables the characterization of the topology of the particle-hole symmetric band structure in terms of band inversions. The topological phase diagrams this leads to are then obtained analytically and exactly. They reveal that, because of the underlying sublattice structure, the existence of topological superconducting phases requires a minimum doping fixed by the strength of the Rashba spin orbit. Majorana boundary quasiparticles are finally predicted to emerge when the Fermi level lies in the vicinity of the bottom (top) of the conduction (valence) band in semiconductors such as the dimerized Peierls chain and phosphorene. In a two-dimensional topological superconductor based on (stretched) graphene, which is semimetallic, Majorana quasiparticles cannot emerge at zero and low doping, that is, when the Fermi level is close to the Dirac points. Nevertheless, they are likely to appear in the vicinity of the van Hove singularities.

  15. Toward a standardized structural-functional group connectome in MNI space.

    Science.gov (United States)

    Horn, Andreas; Blankenburg, Felix

    2016-01-01

    The analysis of the structural architecture of the human brain in terms of connectivity between its subregions has provided profound insights into its underlying functional organization and has coined the concept of the "connectome", a structural description of the elements forming the human brain and the connections among them. Here, as a proof of concept, we introduce a novel group connectome in standard space based on a large sample of 169 subjects from the Enhanced Nathan Kline Institute-Rockland Sample (eNKI-RS). Whole brain structural connectomes of each subject were estimated with a global tracking approach, and the resulting fiber tracts were warped into standard stereotactic (MNI) space using DARTEL. Employing this group connectome, the results of published tracking studies (i.e., the JHU white matter and Oxford thalamic connectivity atlas) could be largely reproduced directly within MNI space. In a second analysis, a study that examined structural connectivity between regions of a functional network, namely the default mode network, was reproduced. Voxel-wise structural centrality was then calculated and compared to others' findings. Furthermore, including additional resting-state fMRI data from the same subjects, structural and functional connectivity matrices between approximately forty thousand nodes of the brain were calculated. This was done to estimate structure-function agreement indices of voxel-wise whole brain connectivity. Taken together, the combination of a novel whole brain fiber tracking approach and an advanced normalization method led to a group connectome that allowed (at least heuristically) performing fiber tracking directly within MNI space. Such an approach may be used for various purposes like the analysis of structural connectivity and modeling experiments that aim at studying the structure-function relationship of the human connectome. Moreover, it may even represent a first step toward a standard DTI template of the human brain

  16. Multiple Imputation Strategies for Multiple Group Structural Equation Models

    Science.gov (United States)

    Enders, Craig K.; Gottschall, Amanda C.

    2011-01-01

    Although structural equation modeling software packages use maximum likelihood estimation by default, there are situations where one might prefer to use multiple imputation to handle missing data rather than maximum likelihood estimation (e.g., when incorporating auxiliary variables). The selection of variables is one of the nuances associated…

  17. Synthesis and structural study of platinum group metal complexes ...

    Indian Academy of Sciences (India)

    )Cl]2, [CpRu(PPh3)2Cl] and [Cp∗M(-Cl)Cl]2, respectively, in the presence of NH4PF6. They were characterized by the following techniques viz. IR, NMR, mass spectrometry and UV-visible spectroscopy. The molecular structures of [2] and [7] ...

  18. Stability assessment of structures under earthquake hazard through GRID technology

    Science.gov (United States)

    Prieto Castrillo, F.; Boton Fernandez, M.

    2009-04-01

    This work presents a GRID framework to estimate the vulnerability of structures under earthquake hazard. The tool has been designed to cover the needs of a typical earthquake engineering stability analysis; preparation of input data (pre-processing), response computation and stability analysis (post-processing). In order to validate the application over GRID, a simplified model of structure under artificially generated earthquake records has been implemented. To achieve this goal, the proposed scheme exploits the GRID technology and its main advantages (parallel intensive computing, huge storage capacity and collaboration analysis among institutions) through intensive interaction among the GRID elements (Computing Element, Storage Element, LHC File Catalogue, federated database etc.) The dynamical model is described by a set of ordinary differential equations (ODE's) and by a set of parameters. Both elements, along with the integration engine, are encapsulated into Java classes. With this high level design, subsequent improvements/changes of the model can be addressed with little effort. In the procedure, an earthquake record database is prepared and stored (pre-processing) in the GRID Storage Element (SE). The Metadata of these records is also stored in the GRID federated database. This Metadata contains both relevant information about the earthquake (as it is usual in a seismic repository) and also the Logical File Name (LFN) of the record for its later retrieval. Then, from the available set of accelerograms in the SE, the user can specify a range of earthquake parameters to carry out a dynamic analysis. This way, a GRID job is created for each selected accelerogram in the database. At the GRID Computing Element (CE), displacements are then obtained by numerical integration of the ODE's over time. The resulting response for that configuration is stored in the GRID Storage Element (SE) and the maximum structure displacement is computed. Then, the corresponding

  19. Synthesis and structural study of platinum group metal complexes ...

    Indian Academy of Sciences (India)

    als by a number of ways yielding mono and dinu- clear compounds. It can also coordinate through pyri- dine and pyrazolyl nitrogens or nitrogens of pyrimidine and pyrazolyl group to form mono and dinuclear com- plexes. However, in the ..... This downfield chemical shift of phosphorus nucleus indicates the formation of ...

  20. Emergence of spatial structure in cell groups and the evolution of cooperation.

    Directory of Open Access Journals (Sweden)

    Carey D Nadell

    2010-03-01

    Full Text Available On its own, a single cell cannot exert more than a microscopic influence on its immediate surroundings. However, via strength in numbers and the expression of cooperative phenotypes, such cells can enormously impact their environments. Simple cooperative phenotypes appear to abound in the microbial world, but explaining their evolution is challenging because they are often subject to exploitation by rapidly growing, non-cooperative cell lines. Population spatial structure may be critical for this problem because it influences the extent of interaction between cooperative and non-cooperative individuals. It is difficult for cooperative cells to succeed in competition if they become mixed with non-cooperative cells, which can exploit the public good without themselves paying a cost. However, if cooperative cells are segregated in space and preferentially interact with each other, they may prevail. Here we use a multi-agent computational model to study the origin of spatial structure within growing cell groups. Our simulations reveal that the spatial distribution of genetic lineages within these groups is linked to a small number of physical and biological parameters, including cell growth rate, nutrient availability, and nutrient diffusivity. Realistic changes in these parameters qualitatively alter the emergent structure of cell groups, and thereby determine whether cells with cooperative phenotypes can locally and globally outcompete exploitative cells. We argue that cooperative and exploitative cell lineages will spontaneously segregate in space under a wide range of conditions and, therefore, that cellular cooperation may evolve more readily than naively expected.

  1. Structural Health Monitoring under Nonlinear Environmental or Operational Influences

    Directory of Open Access Journals (Sweden)

    Jyrki Kullaa

    2014-01-01

    Full Text Available Vibration-based structural health monitoring is based on detecting changes in the dynamic characteristics of the structure. It is well known that environmental or operational variations can also have an influence on the vibration properties. If these effects are not taken into account, they can result in false indications of damage. If the environmental or operational variations cause nonlinear effects, they can be compensated using a Gaussian mixture model (GMM without the measurement of the underlying variables. The number of Gaussian components can also be estimated. For the local linear components, minimum mean square error (MMSE estimation is applied to eliminate the environmental or operational influences. Damage is detected from the residuals after applying principal component analysis (PCA. Control charts are used for novelty detection. The proposed approach is validated using simulated data and the identified lowest natural frequencies of the Z24 Bridge under temperature variation. Nonlinear models are most effective if the data dimensionality is low. On the other hand, linear models often outperform nonlinear models for high-dimensional data.

  2. Anatomical position of the asterion and its underlying structure.

    Science.gov (United States)

    Sripairojkul, B; Adultrakoon, A

    2000-09-01

    Surface anatomy is important for surgical planning. The asterion has been believed and used for locating the underlying posterior fossa dura. To prove whether this landmark is reliable or not, forty-three fixed heads of cadaver were dissected. A burr hole was made on the asterion and its underlying structure was examined. Seventy-four point four per cent (74.4%) of the asterion on the right side were adjacent to the transverse-sigmoid sinus complex when compared to 58.1 per cent on the left. Twenty-three point three per cent (23.3%) of the asterion on the right side were found over the infratentorial dura while that on the left side were 32.6 per cent. Two point three per cent (2.3%) of the asterion were located over the supratentorial dura on the right and 9.3 per cent on the left side. It is concluded, therefore, that the asterion is not an appropriate landmark to locate the underlying posterior fossa dura.

  3. Conformal maps and group contractions in nuclear structure

    International Nuclear Information System (INIS)

    Bonatsos, D.

    2011-01-01

    In mathematics, a conformal map is a function which preserves angles. We show how this procedure can be used in the framework of the Bohr Hamiltonian, leading to a Hamiltonian in a curved space, in which the mass depends on the nuclear deformation β, while it remains independent of the collective variable γ and the three Euler angles. This Hamiltonian is proved to be equivalent to that obtained using techniques of Supersymmetric Quantum Mechanics. Group contraction is a procedure in which a symmetry group is reduced into a group of lower symmetry in a certain limiting case. Examples are provided in the large boson number limit of the Interacting Boson Approximation (IBA) model by a) the contraction of the SU(3) algebra into the [R 5 ]SO(3) algebra of the rigid rotator, consisting of the angular momentum operators forming SO(3), plus 5 mutually commuting quantities, the quadrupole operators, b) the contraction of the O(6) algebra into the [R 5 ]SO(5) algebra of the γ-unstable rotator. We show how contractions can be used for constructing symmetry lines in the interior of the symmetry triangle of the IBA model. (author)

  4. Size-dependent structure of silver nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Koski, Kristie Jo [Univ. of California, Berkeley, CA (United States)

    2008-12-31

    Silver noble metal nanoparticles that are<10 nm often possess multiply twinned grains allowing them to adopt shapes and atomic structures not observed in bulk materials. The properties exhibited by particles with multiply twinned polycrystalline structures are often far different from those of single-crystalline particles and from the bulk. I will present experimental evidence that silver nanoparticles<10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. Results for nanoparticles in the intermediate size range of 5 to 10 nm suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. I propose a mechanism for this transitiion that considers the bond-length distribution in idealized multiply twinned icosahedral particles. Results for nanoparticles of 3.9 nm suggest a reversible linear pressure-dependent orthorhombic distortion. This distortion is interpreted in the context of idealized decahedral particles. In addition, given these size-dependent measurements of silver nanoparticle compression with pressure, we have constructed a pressure calibration curve. Encapsulating these silver nanoparticles in hollow metal oxide nanospheres then allows us to measure the pressure inside a nanoshell using x-ray diffraction. We demonstrate the measurement of pressure gradients across nanoshells and show that these nanoshells have maximum resolved shear strengths on the order of 500 MPa to IGPa.

  5. The Effect of Wave Grouping on On-Shore Structures

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    1979-01-01

    generated solely in accordance with an energy spectrum obtained from field data can be used. To investigate the importance of the succession of waves to the impact on coastal structures, run-up/down on permeable and impermeable slopes and stability of dolos armour were investigated in model tests by using......-up/down and to the stability of dolos armour is shown. A proposal to establish a set of universal graphs for the stability of dolos blocks (or any other “interlocking” blocks) is made....

  6. SMIM1 underlies the Vel blood group and influences red blood cell traits

    DEFF Research Database (Denmark)

    Cvejic, Ana; Haer-Wigman, Lonneke; Stephens, Jonathan C

    2013-01-01

    The blood group Vel was discovered 60 years ago, but the underlying gene is unknown. Individuals negative for the Vel antigen are rare and are required for the safe transfusion of patients with antibodies to Vel. To identify the responsible gene, we sequenced the exomes of five individuals negative...... and expression of the Vel antigen on SMIM1-transfected cells confirm SMIM1 as the gene underlying the Vel blood group. An expression quantitative trait locus (eQTL), the common SNP rs1175550 contributes to variable expression of the Vel antigen (P = 0.003) and influences the mean hemoglobin concentration of red...... blood cells (RBCs; P = 8.6 × 10(-15)). In vivo, zebrafish with smim1 knockdown showed a mild reduction in the number of RBCs, identifying SMIM1 as a new regulator of RBC formation. Our findings are of immediate relevance, as the homozygous presence of the deletion allows the unequivocal identification...

  7. The density matrix renormalization group and nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Pittel, S.; Thakur, B. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Sandulescu, N. [Institute of Physics and Nuclear Engineering, 76900 Bucharest (Romania)

    2007-12-15

    We briefly review the Density Matrix Renormalization Group (DMRG) method and its potential use in large-scale nuclear shell-model calculations. We propose the use of angular-momentum-conserving variant of the method (the JDMRG) and report the first test results of such an approach for the nucleus {sup 48}Cr The positive results of these calculations have motivated us to search for an even more efficient means of implementing the DMRG strategy and the status of these efforts is also described. (Author)

  8. Simulating the service life performance of an inspected group of jacket-type structures

    DEFF Research Database (Denmark)

    Schneider, Ronald; Thöns, Sebastian; Rogge, Andreas

    2017-01-01

    failure probability conditional on simulated inspection and repair histories, and evaluates the associated costs and risk. The expected total service life costs and risk for a strategy are finally determined using Monte Carlo simulation. The optimal strategy minimizes the expected total service life costs...... and risk. We intend to adopt this approach to optimize inspection, monitoring and repair activities for offshore wind park support structures. As a first step, we simulate – in analogy to an offshore wind park – the service life performance of an inspected group of jacket-type frames. The performance...... is quantified in terms of the group’s system failure probability conditional on simulated inspection and repair histories. The underlying system model accounts for the structural redundancy of the frames and the interdependence among their failure events due to similar loading conditions. The model also...

  9. The Electronic Structure and Spectra of Triphenylamines Functionalized by Phenylethynyl Groups

    Science.gov (United States)

    Baryshnikov, G. V.; Minaeva, V. A.; Minaev, B. F.; Grigoras, M.

    2018-01-01

    We study the features of the electronic structure and the IR, UV, and visible spectra of a series of triphenylamines substituted with phenylethynyl groups. The analysis is performed at the level of the density functional theory (DFT) and its nonstationary version in comparison with the experimental data of IR and electron spectroscopy. It is shown that, in the excited state, there is a change in the alternation of single, double, and triple bonds in accordance with the character of bonding and antibonding in the lowest vacant molecular orbital. The gradual introduction of additional phenylethynyl groups does not cause frequency shifts in the IR spectra of the molecules under study, but significantly affects the intensity of the corresponding IR bands. A similar effect is also observed in the electronic-absorption spectra of these compounds. This can be used for optical tuning of triphenylamines as promising materials for organic light-emitting diodes and solar cells.

  10. Introductory group theory and its application to molecular structure

    CERN Document Server

    Ferraro, John R

    1969-01-01

    This volume is a consequence of a series of seminars presented by the authors at the Infrared Spectroscopy Institute, Canisius College, Buffalo, New York, over the last nine years. Many participants on an intermediate level lacked a sufficient background in mathematics and quantum mechan­ ics, and it became evident that a non mathematical or nearly nonmathe­ matical approach would be necessary. The lectures were designed to fill this need and proved very successful. As a result of the interest that was developed in this approach, it was decided to write this book. The text is intended for scientists and students with only limited theore­ tical background in spectroscopy, but who are sincerely interested in the interpretation of molecular spectra. The book develops the detailed selection rules for fundamentals, combinations, and overtones for molecules in several point groups. Detailed procedures used in carrying out the normal coordinate treatment for several molecules are also presented. Numerous examples...

  11. Instrumental variables estimation under a structural Cox model

    DEFF Research Database (Denmark)

    Martinussen, Torben; Nørbo Sørensen, Ditte; Vansteelandt, Stijn

    2017-01-01

    Instrumental variable (IV) analysis is an increasingly popular tool for inferring the effect of an exposure on an outcome, as witnessed by the growing number of IV applications in epidemiology, for instance. The majority of IV analyses of time-to-event endpoints are, however, dominated by heuristic...... and instruments. We propose a novel class of estimators and derive their asymptotic properties. The methodology is illustrated using two real data applications, and using simulated data....... approaches. More rigorous proposals have either sidestepped the Cox model, or considered it within a restrictive context with dichotomous exposure and instrument, amongst other limitations. The aim of this article is to reconsider IV estimation under a structural Cox model, allowing for arbitrary exposure...

  12. Graded Geometric Structures Underlying F-Theory Related Defect Theories

    Science.gov (United States)

    Oikonomou, V. K.

    2013-08-01

    In the context of F-theory, we study the related eight-dimensional super-Yang-Mills theory and reveal the underlying supersymmetric quantum mechanics algebra that the fermionic fields localized on the corresponding defect theory are related to. Particularly, the localized fermionic fields constitute a graded vector space, and in turn this graded space enriches the geometric structures that can be built on the initial eight-dimensional space. We construct the implied composite fiber bundles, which include the graded affine vector space and demonstrate that the composite sections of this fiber bundle are in one-to-one correspondence to the sections of the square root of the canonical bundle corresponding to the submanifold on which the zero modes are localized.

  13. Behavior of grid-stiffened composite structures under transverse loading

    Science.gov (United States)

    Gan, Changsheng

    The energy absorption characteristics and failure modes of grid-stiffened composite plates under transverse load were studied in detail. Several laboratory scale composite grid plates were fabricated by using co-mingled E-glass fiber/polypropylene matrix and carbon/nylon composites in a thermoplastic stamping process. Both experimental and finite element approaches were used to evaluate and understand the role of major failure modes on the performance of damaged grid-stiffened composite plates under transverse load. The load-deflection responses of grid-stiffened composite plates were determined and compared with those of sandwich composite plates of the same size. The failure modes of grid-stiffened composite plates under different load conditions were investigated and used as the basis for FEA models. The intrinsic strength properties of constituent composite materials were measured by using either three point bending or tensile test and were used as input data to the FEA models. Several FEA models including the major failure modes based on the experimental results were built to simulate the damage processes of grid-stiffened composite plates under transverse load. A FORTRAN subroutine was implemented within the ABAQUS code to incorporate the material failure models. Effects of damage on the modal frequencies and loss factors of grid-stiffened composite plates were also investigated experimentally. Experimental and simulation results showed that sandwich composite specimens failed catastrophically with the load dropping sharply at the displacement corresponding to initial and final failure. However, grid-stiffened composite specimens failed in a more gradual and forgiving way in a sequence of relatively small load drops. No catastrophic load drops were observed in the grid structures over the range of displacements investigated here. The SEA values of the grid composite specimens are typically higher than those of the sandwich specimens with the same boundary

  14. Structural evolution of zirconium carbide under ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gosset, D. [CEA Saclay, DEN/DMN/SRMA, F-91191 Gif/Yvette cedex (France)], E-mail: dominique.gosset@cea.fr; Dolle, M. [CEMES-CNRS (UPR 8011), BP 94347, F-31055 Toulouse cedex 4 (France); Simeone, D. [CEA Saclay, DEN/DMN/SRMA, F-91191 Gif/Yvette cedex (France); Baldinozzi, G. [SPMS, Ecole Centrale Paris, F-92295 Chatenay-Malabry cedex (France); Thome, L. [CSNSM, bat. 108, F-91405 Orsay (France)

    2008-02-15

    Zirconium carbide is one of the candidate materials to be used for some fuel components of the high temperature nuclear reactors planned in the frame of the Gen-IV project. Few data exist regarding its behaviour under irradiation. We have irradiated ZrC samples at room temperature with slow heavy ions (4 MeV Au, fluence from 10{sup 11} to 5 x 10{sup 15} cm{sup -2}) in order to simulate neutron irradiations. Grazing incidence X-Ray diffraction (GIXRD) and transmission electron microscopy (TEM) analysis have been performed in order to study the microstructural evolution of the material versus ion fluence. A high sensitivity to oxidation is observed with the formation of zirconia precipitates during the ion irradiations. Three damage stages are observed. At low fluence (<10{sup 12} cm{sup -2}), low modifications are observed. At intermediate fluence, high micro-strains appear together with small faulted dislocation loops. At the highest fluence (>10{sup 14} cm{sup -2}), the micro-strains saturate and the loops coalesce to form a dense dislocation network. No other structural modification is observed. The material shows a moderate cell parameter increase, corresponding to a 0.6 vol.% swelling, which saturates around 10{sup 14} ions/cm{sup 2}, i.e., a few Zr dpa. As a result, in spite of a strong covalent bonding component, ZrC seems to have a behaviour under irradiation close to cubic metals.

  15. Analysis of Dynamic Properties of Piezoelectric Structure under Impact Load

    Directory of Open Access Journals (Sweden)

    Taotao Zhang

    2015-10-01

    Full Text Available An analytical model of the dynamic properties is established for a piezoelectric structure under impact load, without considering noise and perturbations in this paper. Based on the general theory of piezo-elasticity and impact mechanics, the theoretical solutions of the mechanical and electrical fields of the smart structure are obtained with the standing and traveling wave methods, respectively. The comparisons between the two methods have shown that the standing wave method is better for studying long-time response after an impact load. In addition, good agreements are found between the theoretical and the numerical results. To simulate the impact load, both triangle and step pulse loads are used and comparisons are given. Furthermore, the influence of several parameters is discussed so as to provide some advices for practical use. It can be seen that the proposed analytical model would benefit, to some extent, the design and application (especially the airport runway of the related smart devices by taking into account their impact load performance.

  16. BACKSTEPPING ALGORITHM FOR LINEAR SISO PLANTS UNDER STRUCTURAL UNCERTAINTIES

    Directory of Open Access Journals (Sweden)

    I. B. Furtat

    2016-01-01

    Full Text Available The robust algorithm is proposed for parametric and structurally uncertain linear plants under external bounded disturbances. The structural uncertainty is an unknown dynamic order of the model of plants. The developed algorithm provides plant output tracking for a smooth bounded reference signal with a required accuracy at a finite time. It is assumed that only scalar input and output of the plants are available for measurement, but not their derivatives. For the synthesis of the control algorithm we use a modified backstepping algorithm. The synthesis of control algorithm is separated into rsteps, where ris an upper bound of the relative degree of control plant model. At each step we synthesize auxiliary controls that stabilize each subsystem about a zero. At the last step we synthesize a basic control law, which provides output tracking for smooth reference signal. It is shown that for the implementation of the algorithm we need to use only one filter of the control signal and the simplified control laws obtained by application of the real derivative elements. It allows simplifying significantly the calculation and implementation of the control system. Numerical examples and results of computer simulation are given, illustrating the operation of the proposed scheme.

  17. Multivariate analysis of chromatographic retention data as a supplementary means for grouping structurally related compounds.

    Science.gov (United States)

    Fasoula, S; Zisi, Ch; Sampsonidis, I; Virgiliou, Ch; Theodoridis, G; Gika, H; Nikitas, P; Pappa-Louisi, A

    2015-03-27

    In the present study a series of 45 metabolite standards belonging to four chemically similar metabolite classes (sugars, amino acids, nucleosides and nucleobases, and amines) was subjected to LC analysis on three HILIC columns under 21 different gradient conditions with the aim to explore whether the retention properties of these analytes are determined from the chemical group they belong. Two multivariate techniques, principal component analysis (PCA) and discriminant analysis (DA), were used for statistical evaluation of the chromatographic data and extraction similarities between chemically related compounds. The total variance explained by the first two principal components of PCA was found to be about 98%, whereas both statistical analyses indicated that all analytes are successfully grouped in four clusters of chemical structure based on the retention obtained in four or at least three chromatographic runs, which, however should be performed on two different HILIC columns. Moreover, leave-one-out cross-validation of the above retention data set showed that the chemical group in which an analyte belongs can be 95.6% correctly predicted when the analyte is subjected to LC analysis under the same four or three experimental conditions as the all set of analytes was run beforehand. That, in turn, may assist with disambiguation of analyte identification in complex biological extracts. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Lack of congruence in species diversity indices and community structures of planktonic groups based on local environmental factors.

    Science.gov (United States)

    Doi, Hideyuki; Chang, Kwang-Hyeon; Nishibe, Yuichiro; Imai, Hiroyuki; Nakano, Shin-ichi

    2013-01-01

    The importance of analyzing the determinants of biodiversity and community composition by using multiple trophic levels is well recognized; however, relevant data are lacking. In the present study, we investigated variations in species diversity indices and community structures of the plankton taxonomic groups-zooplankton, rotifers, ciliates, and phytoplankton-under a range of local environmental factors in pond ecosystems. For each planktonic group, we estimated the species diversity index by using linear models and analyzed the community structure by using canonical correspondence analysis. We showed that the species diversity indices and community structures varied among the planktonic groups and according to local environmental factors. The observed lack of congruence among the planktonic groups may have been caused by niche competition between groups with similar trophic guilds or by weak trophic interactions. Our findings highlight the difficulty of predicting total biodiversity within a system, based upon a single taxonomic group. Thus, to conserve the biodiversity of an ecosystem, it is crucial to consider variations in species diversity indices and community structures of different taxonomic groups, under a range of local conditions.

  19. Modification of C60/C70+Pd film structure under electric field influence during electron emission

    International Nuclear Information System (INIS)

    Czerwosz, E.; Dluzewski, P.; Kozlowski, M.

    2001-01-01

    We investigated the modification of structure of C 60 /C 70 +Pd films during cold electron emission from these films. Films were obtained by vacuum thermal deposition from two sources and were characterised before and after electron emission measurements by transmission electron microscopy and electron diffraction. Films were composed of nanocrystalline Pd objects dispersed in carbon/fullerenes matrix. I-V characteristics for electron emission were obtained in diode geometry with additionally applied voltage along the film surface. The modification of film structure occurred under applied electric field and the grouping of Pd nano crystals into bigger objects was observed

  20. Temporal ventriloquism along the path of apparent motion: speed perception under different spatial grouping principles.

    Science.gov (United States)

    Ogulmus, Cansu; Karacaoglu, Merve; Kafaligonul, Hulusi

    2018-03-01

    The coordination of intramodal perceptual grouping and crossmodal interactions plays a critical role in constructing coherent multisensory percepts. However, the basic principles underlying such coordinating mechanisms still remain unclear. By taking advantage of an illusion called temporal ventriloquism and its influences on perceived speed, we investigated how audiovisual interactions in time are modulated by the spatial grouping principles of vision. In our experiments, we manipulated the spatial grouping principles of proximity, uniform connectedness, and similarity/common fate in apparent motion displays. Observers compared the speed of apparent motions across different sound timing conditions. Our results revealed that the effects of sound timing (i.e., temporal ventriloquism effects) on perceived speed also existed in visual displays containing more than one object and were modulated by different spatial grouping principles. In particular, uniform connectedness was found to modulate these audiovisual interactions in time. The effect of sound timing on perceived speed was smaller when horizontal connecting bars were introduced along the path of apparent motion. When the objects in each apparent motion frame were not connected or connected with vertical bars, the sound timing was more influential compared to the horizontal bar conditions. Overall, our findings here suggest that the effects of sound timing on perceived speed exist in different spatial configurations and can be modulated by certain intramodal spatial grouping principles such as uniform connectedness.

  1. Tracing the evolution of nuclear forces under the similarity renormalization group

    Directory of Open Access Journals (Sweden)

    Calvin W. Johnson

    2017-11-01

    Full Text Available I examine the evolution of nuclear forces under the similarity renormalization group (SRG using traces of the many-body configuration-space Hamiltonian. While SRG is often said to “soften” the nuclear interaction, I provide numerical examples which paint a complementary point of view: the primary effect of SRG, using the kinetic energy as the generator of the evolution, is to shift downward the diagonal matrix elements in the model space, while the off-diagonal elements undergo significantly smaller changes. By employing traces, I argue that this is a very natural outcome as one diagonalizes a matrix, and helps one to understand the success of SRG.

  2. Tracing the evolution of nuclear forces under the similarity renormalization group

    Science.gov (United States)

    Johnson, Calvin W.

    2017-11-01

    I examine the evolution of nuclear forces under the similarity renormalization group (SRG) using traces of the many-body configuration-space Hamiltonian. While SRG is often said to ;soften; the nuclear interaction, I provide numerical examples which paint a complementary point of view: the primary effect of SRG, using the kinetic energy as the generator of the evolution, is to shift downward the diagonal matrix elements in the model space, while the off-diagonal elements undergo significantly smaller changes. By employing traces, I argue that this is a very natural outcome as one diagonalizes a matrix, and helps one to understand the success of SRG.

  3. Unraveling the Molecular Mechanisms Underlying the Nasopharyngeal Bacterial Community Structure

    Directory of Open Access Journals (Sweden)

    Wouter A. A. de Steenhuijsen Piters

    2016-03-01

    Full Text Available The upper respiratory tract is colonized by a diverse array of commensal bacteria that harbor potential pathogens, such as Streptococcus pneumoniae. As long as the local microbial ecosystem—also called “microbiome”—is in balance, these potentially pathogenic bacterial residents cause no harm to the host. However, similar to macrobiological ecosystems, when the bacterial community structure gets perturbed, potential pathogens can overtake the niche and cause mild to severe infections. Recent studies using next-generation sequencing show that S. pneumoniae, as well as other potential pathogens, might be kept at bay by certain commensal bacteria, including Corynebacterium and Dolosigranulum spp. Bomar and colleagues are the first to explore a specific biological mechanism contributing to the antagonistic interaction between Corynebacterium accolens and S. pneumoniae in vitro [L. Bomar, S. D. Brugger, B. H. Yost, S. S. Davies, K. P. Lemon, mBio 7(1:e01725-15, 2016, doi:10.1128/mBio.01725-15]. The authors comprehensively show that C. accolens is capable of hydrolyzing host triacylglycerols into free fatty acids, which display antipneumococcal properties, suggesting that these bacteria might contribute to the containment of pneumococcus. This work exemplifies how molecular epidemiological findings can lay the foundation for mechanistic studies to elucidate the host-microbe and microbial interspecies interactions underlying the bacterial community structure. Next, translation of these results to an in vivo setting seems necessary to unveil the magnitude and importance of the observed effect in its natural, polymicrobial setting.

  4. Current algebras, measures quasi-invariant under diffeomorphism groups, and infinite quantum systems with accumulation points

    Science.gov (United States)

    Sakuraba, Takao

    The approach to quantum physics via current algebra and unitary representations of the diffeomorphism group is established. This thesis studies possible infinite Bose gas systems using this approach. Systems of locally finite configurations and systems of configurations with accumulation points are considered, with the main emphasis on the latter. In Chapter 2, canonical quantization, quantization via current algebra and unitary representations of the diffeomorphism group are reviewed. In Chapter 3, a new definition of the space of configurations is proposed and an axiom for general configuration spaces is abstracted. Various subsets of the configuration space, including those specifying the number of points in a Borel set and those specifying the number of accumulation points in a Borel set are proved to be measurable using this axiom. In Chapter 4, known results on the space of locally finite configurations and Poisson measure are reviewed in the light of the approach developed in Chapter 3, including the approach to current algebra in the Poisson space by Albeverio, Kondratiev, and Rockner. Goldin and Moschella considered unitary representations of the group of diffeomorphisms of the line based on self-similar random processes, which may describe infinite quantum gas systems with clusters. In Chapter 5, the Goldin-Moschella theory is developed further. Their construction of measures quasi-invariant under diffeomorphisms is reviewed, and a rigorous proof of their conjectures is given. It is proved that their measures with distinct correlation parameters are mutually singular. A quasi-invariant measure constructed by Ismagilov on the space of configurations with accumulation points on the circle is proved to be singular with respect to the Goldin-Moschella measures. Finally a generalization of the Goldin-Moschella measures to the higher-dimensional case is studied, where the notion of covariance matrix and the notion of condition number play important roles. A

  5. Structure activity relationships to assess new chemicals under TSCA

    Energy Technology Data Exchange (ETDEWEB)

    Auletta, A.E. [Environmental Protection Agency, Washington, DC (United States)

    1990-12-31

    Under Section 5 of the Toxic Substances Control Act (TSCA), manufacturers must notify the US Environmental Protection Agency (EPA) 90 days before manufacturing, processing, or importing a new chemical substance. This is referred to as a premanufacture notice (PMN). The PMN must contain certain information including chemical identity, production volume, proposed uses, estimates of exposure and release, and any health or environmental test data that are available to the submitter. Because there is no explicit statutory authority that requires testing of new chemicals prior to their entry into the market, most PMNs are submitted with little or no data. As a result, EPA has developed special techniques for hazard assessment of PMN chemicals. These include (1) evaluation of available data on the chemical itself, (2) evaluation of data on analogues of the PMN, or evaluation of data on metabolites or analogues of metabolites of the PMN, (3) use of quantitative structure activity relationships (QSARs), and (4) knowledge and judgement of scientific assessors in the interpretation and integration of the information developed in the course of the assessment. This approach to evaluating potential hazards of new chemicals is used to identify those that are most in need of addition review of further testing. It should not be viewed as a replacement for testing. 4 tabs.

  6. Interevent relationships and judgment under uncertainty: structure determines strategy.

    Science.gov (United States)

    Sanfey, Alan G; Hastie, Reid

    2002-09-01

    A fundamental empirical question regarding judgments about events is whether experienced absolute frequencies or relative frequencies are relied on when the likelihood of a particular occurrence is judged. The present research explicates the conditions under which people rely on remembered raw absolute frequencies versus on inferred relative frequencies or proportions when making predictions. Participants saw opinion poll results for candidates prior to an election and, on the basis of these, made judgments concerning the likelihood of each candidate's winning this election. Certain candidates demonstrated a high absolute frequency of winning in the polls, whereas other candidates had high relative win frequencies. The results indicated that adults are cognitively flexible with regard to the inputs used in this judgment. Certain stimulus event configurations induced reasoning by way of absolute frequencies, whereas other configurations elicited judgments based on relative frequencies. More specifically, as the relational complexity of the event structure increased and more inferences were required to make predictions, the tendency to rely on absolute, as opposed to relative, frequencies also increased.

  7. Sub-fragmentation of structural reactive material casings under explosion

    Science.gov (United States)

    Zhang, Fan; Gauthier, Maxime; Cojocaru, Cristian

    2017-01-01

    A concept of reactive hot spots intruded in a thick, structural reactive material casing was investigated to generate fine fragments for efficient energy release from casing material under explosive loading. This was achieved through distributing micro MoO3 particles into a granular Al casing, made by hot isostatic pressing, in a fuel-rich ratio of 10Al+MoO3. Reaction of Al and MoO3 during casing primary or secondary fragmentation creates heat and gas products to form micro-scale hot spots, whose expansion initiates local fractures leading to fine fragments of the rest of Al. Explosion experiments, using a 4.4 cm diameter cased charge with a casing-to-explosive mass ratio of 1.78 in a 2.1 m3 cylindrical chamber, demonstrated the presence of fine fragments and more efficient fragment combustion to augment air blast, as compared to a baseline pure Al-cased charge, thus indicating the feasibility of the concept.

  8. Identification of Previously Unknown Groups of Microorganisms Under the Tundra Snowpack

    Science.gov (United States)

    Schmidt, S.; Schadt, C. W.; Lipson, D. A.; Martin, A. P.

    2003-12-01

    Recent work has shown that microbial communities are active under snow. In fact, in some tundra soils these organisms reach their year-round peak in late winter. These communities can function at temperatures down to at least -5° C and are fuelled by dead plant material laid down in the Autumn. Until now the identity of these cold adapted microbial communities was a complete mystery. We used microbiological and molecular techniques to elucidate the phylogenetic composition of these under-snow microbial communities. At the broadest taxonomic level, we show that fungi dominate the under-snow world. More detailed molecular analyses revealed a high diversity within the fungi and we identified three clades that constitute major new groups of fungi (at the subphylum or class level) that have not been previously described or cultured. An abundance of hitherto unknown fungi that are active beneath the snow significantly broadens our understanding of both the diversity and biogeochemical functioning of fungi in cold environments.

  9. Structure and function studies on enzymes with a catalytic carboxyl group(s): from ribonuclease T1 to carboxyl peptidases

    Science.gov (United States)

    TAKAHASHI, Kenji

    2013-01-01

    A group of enzymes, mostly hydrolases or certain transferases, utilize one or a few side-chain carboxyl groups of Asp and/or Glu as part of the catalytic machinery at their active sites. This review follows mainly the trail of studies performed by the author and his colleagues on the structure and function of such enzymes, starting from ribonuclease T1, then extending to three major types of carboxyl peptidases including aspartic peptidases, glutamic peptidases and serine-carboxyl peptidases. PMID:23759941

  10. Emergence of leadership in a robotic fish group under diverging individual personality traits.

    Science.gov (United States)

    Wang, Chen; Chen, Xiaojie; Xie, Guangming; Cao, Ming

    2017-05-01

    Variations of individual's personality traits have been identified before as one of the possible mechanisms for the emergence of leadership in an interactive collective, which may lead to benefits for the group as a whole. Complementing the large number of existing literatures on using simulation models to study leadership, we use biomimetic robotic fish to gain insight into how the fish's behaviours evolve under the influence of the physical hydrodynamics. In particular, we focus in this paper on understanding how robotic fish's personality traits affect the emergence of an effective leading fish in repeated robotic foraging tasks when the robotic fish's strategies, to push or not to push the obstacle in its foraging path, are updated over time following an evolutionary game set-up. We further show that the robotic fish's personality traits diverge when the group carries out difficult foraging tasks in our experiments, and self-organization takes place to help the group to adapt to the level of difficulties of the tasks without inter-individual communication.

  11. Teenage Dropouts and Drug Use: Does the Specification of Peer Group Structure Matter?

    Science.gov (United States)

    Glaser, Darrell J.

    2009-01-01

    Four alternative structures of peer groups are compared in an empirical analysis of teenage dropouts and recent drug use. In general, individual-specific covariates remain robust regardless of group structure specification in dropout models, but lose significance in models of drug-use. Estimates of correlated school effects depend on the…

  12. Under-represented students' engagement in secondary science learning: A non-equivalent control group design

    Science.gov (United States)

    Vann-Hamilton, Joy J.

    Problem. A significant segment of the U.S. population, under-represented students, is under-engaged or disengaged in secondary science education. International and national assessments and various research studies illuminate the problem and/or the disparity between students' aspirations in science and the means they have to achieve them. To improve engagement and address inequities among these students, more contemporary and/or inclusive pedagogy is recommended. More specifically, multicultural science education has been suggested as a potential strategy for increased equity so that all learners have access to and are readily engaged in quality science education. While multicultural science education emphasizes the integration of students' backgrounds and experiences with science learning , multimedia has been suggested as a way to integrate the fundamentals of multicultural education into learning for increased engagement. In addition, individual characteristics such as race, sex, academic track and grades were considered. Therefore, this study examined the impact of multicultural science education, multimedia, and individual characteristics on under-represented students' engagement in secondary science. Method. The Under-represented Students Engagement in Science Survey (USESS), an adaptation of the High School Survey of Student Engagement, was used with 76 high-school participants. The USESS was used to collect pretest and posttest data concerning their types and levels of student engagement. Levels of engagement were measured with Strongly Agree ranked as 5, down to Strongly Disagree ranked at 1. Participants provided this feedback prior to and after having interacted with either the multicultural or the non-multicultural version of the multimedia science curriculum. Descriptive statistics for the study's participants and the survey items, as well as Cronbach's alpha coefficient for internal consistency reliability with respect to the survey subscales, were

  13. Studies on Pounding Response Considering Structure-Soil-Structure Interaction under Seismic Loads

    Directory of Open Access Journals (Sweden)

    Peizhen Li

    2017-12-01

    Full Text Available Pounding phenomena considering structure–soil–structure interaction (SSSI under seismic loads are investigated in this paper. Based on a practical engineering project, this work presents a three-dimensional finite element numerical simulation method using ANSYS software. According to Chinese design code, the models of adjacent shear wall structures on Shanghai soft soil with the rigid foundation, box foundation and pile foundation are built respectively. In the simulation, the Davidenkov model of the soil skeleton curve is assumed for soil behavior, and the contact elements with Kelvin model are adopted to simulate pounding phenomena between adjacent structures. Finally, the dynamic responses of adjacent structures considering the pounding and SSSI effects are analyzed. The results show that pounding phenomena may occur, indicating that the seismic separation requirement for adjacent buildings of Chinese design code may not be enough to avoid pounding effect. Pounding and SSSI effects worsen the adjacent buildings’ conditions because their acceleration and shear responses are amplified after pounding considering SSSI. These results are significant for studying the effect of pounding and SSSI phenomena on seismic responses of structures and national sustainable development, especially in earthquake prevention and disaster reduction.

  14. Reconstruction of ancestral RNA sequences under multiple structural constraints

    OpenAIRE

    Tremblay-Savard, Olivier; Reinharz, Vladimir; Waldisp?hl, J?r?me

    2016-01-01

    Background Secondary structures form the scaffold of multiple sequence alignment of non-coding RNA (ncRNA) families. An accurate reconstruction of ancestral ncRNAs must use this structural signal. However, the inference of ancestors of a single ncRNA family with a single consensus structure may bias the results towards sequences with high affinity to this structure, which are far from the true ancestors. Methods In this paper, we introduce achARNement, a maximum parsimony approach that, given...

  15. Interface stability of granular filter structures under currents

    NARCIS (Netherlands)

    Verheij, H.J.; Hoffmans, G.; Dorst, K.; Van de Sande, S.

    2012-01-01

    Granular filters are used for protection of structures against scour and erosion. For a proper functioning it is necessary that the interfaces between the filter structure, the subsoil and the water flowing above the filter structure are stable. Stability means that there is no transport of subsoil

  16. On the group structure and root system of SL n over a field ...

    African Journals Online (AJOL)

    Given a commutative field F, the Whitehead functor K1 and Steinberge functor K2 are closely related to the theory of general linear group through exact sequences of groups. In this paper, the group structure of SLn over a field F is closely examined and its root system is computed. Only the case n = 3 is considered.

  17. Extending the CLAST sequential rule to one-way ANOVA under group sampling.

    Science.gov (United States)

    Ximénez, Carmen; Revuelta, Javier

    2007-02-01

    Several studies have demonstrated that the fixed-sample stopping rule (FSR), in which the sample size is determined in advance, is less practical and efficient than are sequential-stopping rules. The composite limited adaptive sequential test (CLAST) is one such sequential-stopping rule. Previous research has shown that CLAST is more efficient in terms of sample size and power than are the FSR and other sequential rules and that it reflects more realistically the practice of experimental psychology researchers. The CLAST rule has been applied only to the t test of mean differences with two matched samples and to the chi-square independence test for twofold contingency tables. The present work extends previous research on the efficiency of CLAST to multiple group statistical tests. Simulation studies were conducted to test the efficiency of the CLAST rule for the one-way ANOVA for fixed effects models. The ANOVA general test and two linear contrasts of multiple comparisons among treatment means are considered. The article also introduces four rules for allocating N observations to J groups under the general null hypothesis and three allocation rules for the linear contrasts. Results show that the CLAST rule is generally more efficient than the FSR in terms of sample size and power for one-way ANOVA tests. However, the allocation rules vary in their optimality and have a differential impact on sample size and power. Thus, selecting an allocation rule depends on the cost of sampling and the intended precision.

  18. Robust group fused lasso for multisample copy number variation detection under uncertainty.

    Science.gov (United States)

    Sharifi Noghabi, Hossein; Mohammadi, Majid; Tan, Yao-Hua

    2016-12-01

    One of the most important needs in the post-genome era is providing the researchers with reliable and efficient computational tools to extract and analyse this huge amount of biological data, in which DNA copy number variation (CNV) is a vitally important one. Array-based comparative genomic hybridisation (aCGH) is a common approach in order to detect CNVs. Most of methods for this purpose were proposed for one-dimensional profiles. However, slightly this focus has moved from one- to multi-dimensional signals. In addition, since contamination of these profiles with noise is always an issue, it is highly important to have a robust method for analysing multi-sample aCGH profiles. In this study, the authors propose robust group fused lasso which utilises the robust group total variations. Instead of l 2,1 norm, the l 1 - l 2 M-estimator is used which is more robust in dealing with non-Gaussian noise and high corruption. More importantly, Correntropy (Welsch M-estimator) is also applied for fitting error. Extensive experiments indicate that the proposed method outperforms the state-of-the art algorithms and techniques under a wide range of scenarios with diverse noises.

  19. Optimization and anti-optimization of structures under uncertainty

    National Research Council Canada - National Science Library

    Elishakoff, Isaac; Ohsaki, Makoto

    2010-01-01

    The volume presents a collaboration between internationally recognized experts on anti-optimization and structural optimization, and summarizes various novel ideas, methodologies and results studied over 20 years...

  20. Peak earthquake response of structures under multi-component excitations

    Science.gov (United States)

    Song, Jianwei; Liang, Zach; Chu, Yi-Lun; Lee, George C.

    2007-12-01

    Accurate estimation of the peak seismic responses of structures is important in earthquake resistant design. The internal force distributions and the seismic responses of structures are quite complex, since ground motions are multi-directional. One key issue is the uncertainty of the incident angle between the directions of ground motion and the reference axes of the structure. Different assumed seismic incidences can result in different peak values within the scope of design spectrum analysis for a given structure and earthquake ground motion record combination. Using time history analysis to determine the maximum structural responses excited by a given earthquake record requires repetitive calculations to determine the critical incident angle. This paper presents a transformation approach for relatively accurate and rapid determination of the maximum peak responses of a linear structure subjected to three-dimensional excitations within all possible seismic incident angles. The responses can be deformations, internal forces, strains and so on. An irregular building structure model is established using SAP2000 program. Several typical earthquake records and an artificial white noise are applied to the structure model to illustrate the variation of the maximum structural responses for different incident angles. Numerical results show that for many structural parameters, the variation can be greater than 100%. This method can be directly applied to time history analysis of structures using existing computer software to determine the peak responses without carrying out the analyses for all possible incident angles. It can also be used to verify and/or modify aseismic designs by using response spectrum analysis.

  1. Nest Digging by Leaf-Cutting Ants: Effect of Group Size and Functional Structures

    Directory of Open Access Journals (Sweden)

    Roberto da Silva Camargo

    2012-01-01

    Full Text Available Leaf-cutting ant workers dig underground chambers, for housing their symbiotic fungus, interconnected by a vast quantity of tunnels whose function is to permit the entrance of food (leaves, gaseous exchanges, and movement of workers, offspring, and the queen. Digging is a task executed by a group of workers, but little is known about the group effect and group-constructed functional structures. Thus, we analyzed the structures formed by worker groups (5, 10, 20, and 40 individuals of the leaf-cutting ant, Atta sexdens rubropilosa, for 2 days of excavation. The digging arena was the same for the 4 groups, with each group corresponding to a different density. Our results verified a pattern of tunneling by the workers, but no chamber was constructed. The group effect is well known, since the 40-worker group dug significantly more than the groups of 5, 10, and 20. These groups did not differ statistically from each other. Analysis of load/worker verified that workers of the smallest group carried the greatest load. Our paper demonstrates the group effect on the digging of nests, namely, that excavation is proportional to group size, but without emergence of a functional structure such as a chamber.

  2. Structural convergence under reversible and irreversible monetary unification

    NARCIS (Netherlands)

    Beetsma, R.M.W.J.; Jensen, H.

    2003-01-01

    We explore endogenous monetary unification in the context of a model in which a country with serious structural distortions (and, hence, high inflation) is admitted into a monetary union once its economic structure has converged sufficiently towards that of the existing participants. If unification

  3. Structural convergence under reversible and irreversible monetary unification

    NARCIS (Netherlands)

    Beetsma, R.M.W.J.; Jensen, H.

    1999-01-01

    We explore endogenous monetary unification in the context of a model in which a country with serious structural distortions (and, hence, high inflation) is admitted into a monetary union once its economic structure has converged sufficiently towards that of the existing participants. If unification

  4. Analysis Of Masonry Infilled RC Frame Structures Under Lateral Loading

    Directory of Open Access Journals (Sweden)

    Barnaure Mircea

    2015-03-01

    Full Text Available Partition walls are often made of masonry in Romania. Although they are usually considered non-structural elements in the case of reinforced concrete framed structures, the infill panels contribute significantly to the seismic behaviour of the building. Their impact is difficult to assess, mainly because the interaction between the bounding frame and the infill is an intricate issue. This paper analyses the structural behaviour of a masonry infilled reinforced concrete frame system subjected to in - plane loading. Three numerical models are proposed and their results are compared in terms of stiffness and strength of the structure. The role of the openings in the infill panel on the behaviour is analysed and discussed. The effect of gaps between the frame and the infill on the structural behaviour is also investigated. Comparisons are made with the in-force Romanian and European regulations provisions.

  5. Under-vaccinated groups in Europe and their beliefs, attitudes and reasons for non-vaccination; two systematic reviews.

    OpenAIRE

    Fournet, N; Mollema, L; Ruijs, W L; Harmsen, I A; Keck, F; Durand, J Y; Cunha, M P; Wamsiedel, M; Reis, R; French, J; Smit, E G; Kitching, A; van Steenbergen, J E

    2018-01-01

    Background: Despite effective national immunisation programmes in Europe, some groups remain incompletely or un-vaccinated ('under-vaccinated'), with underserved minorities and certain religious/ideological groups repeatedly being involved in outbreaks of vaccine preventable diseases (VPD).Gaining insight into factors regarding acceptance of vaccination of 'under-vaccinated groups' (UVGs) might give opportunities to communicate with them in a trusty and reliable manner that respects their bel...

  6. Real-Time Station Grouping under Dynamic Traffic for IEEE 802.11ah.

    Science.gov (United States)

    Tian, Le; Khorov, Evgeny; Latré, Steven; Famaey, Jeroen

    2017-07-04

    RAW grouping under dynamic traffic in real time, which is a major leap towards applying RAW mechanism in real-life IoT networks.

  7. Real-Time Station Grouping under Dynamic Traffic for IEEE 802.11ah

    Science.gov (United States)

    Tian, Le; Latré, Steven

    2017-01-01

    RAW grouping under dynamic traffic in real time, which is a major leap towards applying RAW mechanism in real-life IoT networks. PMID:28677617

  8. Ground Liquefaction and Deformation Analysis of Breakwater Structures Under Earthquakes

    Directory of Open Access Journals (Sweden)

    Zhao Jie

    2016-10-01

    Full Text Available Ground liquefaction and deformation is one of the important causes that damage engineering structures. Chinese current code for seismic design of breakwater is based on the single-level seismic design method as well as code for port and water-way engineering. However, this code can not exactly reflect the seismic performance of breakwater structures which experience different seismic intensities. In this paper, the author used a finite difference software, namely, FLAC3D, to analyze the state and compute seismic responses of breakwater structure. The breakwater foundation’s pore pressure ratio and displacement due to different earthquake have been studied. And the result show that: Smaller earthquakes have little influence on serviceability of the foundation, and severe earthquakes can liquefy some parts of the foundation; In the latter case , obvious changes of pores and foundation displaces can be found. Particularly, when seismic peak acceleration reachs 0.2g, Liquefaction appears in the foundation and mainly concentrated in the upper right side of the structure. In addition, the survey of ultra-hole pressure and displacement values of sand layers of the breakwater, manifests when the ultra pore pressure near 1.0, displacement and overturning structure is relatively large, resulting in varying degrees of damage to the structure. This paper’s research can provide theoretical and designable reference for similar engineering structures

  9. Optimal Design of Composite Structures Under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Marmaras, Konstantinos

    determination of the appropriate laminate thickness and the material choice in the structure. The optimal design problems that arise are stated as nonconvex mixed integer programming problems. We resort to different reformulation techniques to state the optimization problems as either linear or nonlinear convex....... The continuous relaxation of the mixed integer programming problems is being solved by an implementation of a primal–dual interior point method for nonlinear programming that updates the barrier parameter adaptively. The method is chosen for its excellent convergence properties and the ability of the method...... design phase results in structures with better structural performance reducing the need of manually post–processing the found designs....

  10. Harvesting Energy from Vibrations of the Underlying Structure

    DEFF Research Database (Denmark)

    Han, Bo; Vssilaras, S; Papadias, C.B.

    2013-01-01

    The use of wireless sensors for structural health monitoring offers several advantages such as small size, easy installation and minimal intervention on existing structures. However the most significant concern about such wireless sensors is the lifetime of the system, which depends heavily...... to the long-term structural health of a building or bridge, but at the same time they can be exploited as a power source to power the wireless sensors that are monitoring this structural health. This paper presents a new energy harvesting method based on a vibration driven electromagnetic harvester. By using...... on the type of power supply. No matter how energy efficient the operation of a battery operated sensor is, the energy of the battery will be exhausted at some point. In order to achieve a virtually unlimited lifetime, the sensor node should be able to recharge its battery in an easy way. Energy harvesting...

  11. Localized Damage Process in Metal Structures Under High Velocity Deformation

    National Research Council Canada - National Science Library

    Vodenicharov, Stefan

    1999-01-01

    The ASB initiation and growth in high strength steel are investigated. An integrated energy theoretical approach is suggested for modeling ASB development and identifying post critical structure state in the bands...

  12. Determining wildlife use of wildlife crossing structures under different scenarios.

    Science.gov (United States)

    2012-05-01

    This research evaluated Utahs wildlife crossing structures to help UDOT and the Utah Division of Wildlife Resources assess crossing efficacy. In this study, remote motion-sensed cameras were used at 14 designated wildlife crossing culverts and bri...

  13. Performance based investigations of structural systems under fire

    DEFF Research Database (Denmark)

    Gentili, Filippo; Crosti, Chiara; Giuliani, Luisa

    2010-01-01

    Prescriptive measures and procedures developed over the past here are mostly aimed at preventing structural failures of single elements for the time required for the evacuation. The response to fire and fire effects of the structural system as a whole remains often unknown and the survival of the...... structures are presented and discussed, with particular attention to methodological aspects. The effects of different assumptions in the modeling and in the definition of the collapse are highlighted, as critical aspects of a performance-based investigation....... these kinds of events, the mitigation of possible collapse induced by fire should be achieved. In this respect, a performance-based investigation of the structure aimed at highlight fire effects and fire-induced collapse mechanisms becomes of interest. In the paper collapse mechanisms of some simple...

  14. Structural analysis of reinforced concrete structures under monotonous and cyclic loadings: numerical aspects

    International Nuclear Information System (INIS)

    Lepretre, C.; Millard, A.; Nahas, G.

    1989-01-01

    The structural analysis of reinforced concrete structures is usually performed either by means of simplified methods of strength of materials type i.e. global methods, or by means of detailed methods of continuum mechanics type, i.e. local methods. For this second type, some constitutive models are available for concrete and rebars in a certain number of finite element systems. These models are often validated on simple homogeneous tests. Therefore, it is important to appraise the validity of the results when applying them to the analysis of a reinforced concrete structure, in order to be able to make correct predictions of the actual behaviour, under normal and faulty conditions. For this purpose, some tests have been performed at I.N.S.A. de Lyon on reinforced concrete beams, subjected to monotonous and cyclic loadings, in order to generate reference solutions to be compared with the numerical predictions given by two finite element systems: - CASTEM, developed by C.E.A./.D.E.M.T. - ELEFINI, developed by I.N.S.A. de Lyon

  15. Structural Metals in the Group I Intron: A Ribozyme with a Multiple Metal Ion Core

    Energy Technology Data Exchange (ETDEWEB)

    Stahley,M.; Adams, P.; Wang, J.; Strobel, S.

    2007-01-01

    Metal ions play key roles in the folding and function for many structured RNAs, including group I introns. We determined the X-ray crystal structure of the Azoarcus bacterial group I intron in complex with its 5' and 3' exons. In addition to 222 nucleotides of RNA, the model includes 18 Mg2+ and K+ ions. Five of the metals bind within 12 Angstroms of the scissile phosphate and coordinate the majority of the oxygen atoms biochemically implicated in conserved metal-RNA interactions. The metals are buried deep within the structure and form a multiple metal ion core that is critical to group I intron structure and function. Eight metal ions bind in other conserved regions of the intron structure, and the remaining five interact with peripheral structural elements. Each of the 18 metals mediates tertiary interactions, facilitates local bends in the sugar-phosphate backbone or binds in the major groove of helices. The group I intron has a rich history of biochemical efforts aimed to identify RNA-metal ion interactions. The structural data are correlated to the biochemical results to further understand the role of metal ions in group I intron structure and function.

  16. Grid synchronization structure for wind converters under grid fault conditions

    OpenAIRE

    Garcia, Jose Ignacio; Candela García, José Ignacio; Luna Alloza, Álvaro; Catalan, Pedro

    2016-01-01

    This paper presents a grid synchronization structure for three-phase electric power systems based on the use of a filtered quadrature signal generator (FQSG) and a phase-locked loop (PLL) structure, named Adaptive Vector Grid Synchronization system (AVGS). This system estimates the magnitude, frequency and phase of a signal, specially three-phase voltages and currents, and allows fast and accurate detection of the symmetrical components meet with the transient operating requirements imposed b...

  17. Behavior of auxetic structures under compression and impact forces

    Science.gov (United States)

    Yang, Chulho; Vora, Hitesh D.; Chang, Young

    2018-02-01

    In recent years, various auxetic material structures have been designed and fabricated for diverse applications that utilize normal materials that follow Hooke’s law but still show the properties of negative Poisson’s ratios (NPR). One potential application is body protection pads that are comfortable to wear and effective in protecting body parts by reducing impact force and preventing injuries in high-risk individuals such as elderly people, industrial workers, law enforcement and military personnel, and athletes. This paper reports an integrated theoretical, computational, and experimental investigation conducted for typical auxetic materials that exhibit NPR properties. Parametric 3D CAD models of auxetic structures such as re-entrant hexagonal cells and arrowheads were developed. Then, key structural characteristics of protection pads were evaluated through static analyses of FEA models. Finally, impact analyses were conducted through dynamic simulations of FEA models to validate the results obtained from the static analyses. Efforts were also made to relate the individual and/or combined effect of auxetic structures and materials to the overall stiffness and shock-absorption performance of the protection pads. An advanced additive manufacturing (3D printing) technique was used to build prototypes of the auxetic structures. Three different materials typically used for fused deposition modeling technology, namely polylactic acid (PLA) and thermoplastic polyurethane material (NinjaFlex® and SemiFlex®), were used for different stiffness and shock-absorption properties. The 3D printed prototypes were then tested and the results were compared to the computational predictions. The results showed that the auxetic material could be effective in reducing the shock forces. Each structure and material combination demonstrated unique structural properties such as stiffness, Poisson’s ratio, and efficiency in shock absorption. Auxetic structures showed better shock

  18. Oxide glass structure evolution under swift heavy ion irradiation

    International Nuclear Information System (INIS)

    Mendoza, C.; Peuget, S.; Charpentier, T.; Moskura, M.; Caraballo, R.; Bouty, O.; Mir, A.H.; Monnet, I.; Grygiel, C.; Jegou, C.

    2014-01-01

    Highlights: • Structure of SHI irradiated glass is similar to the one of a hyper quenched glass. • D2 Raman band associated to 3 members ring is only observed in irradiated glass. • Irradiated state seems slightly different to an equilibrated liquid quenched rapidly. - Abstract: The effects of ion tracks on the structure of oxide glasses were examined by irradiating a silica glass and two borosilicate glass specimens containing 3 and 6 oxides with krypton ions (74 MeV) and xenon ions (92 MeV). Structural changes in the glass were observed by Raman and nuclear magnetic resonance spectroscopy using a multinuclear approach ( 11 B, 23 Na, 27 Al and 29 Si). The structure of irradiated silica glass resembles a structure quenched at very high temperature. Both borosilicate glass specimens exhibited depolymerization of the borosilicate network, a lower boron coordination number, and a change in the role of a fraction of the sodium atoms after irradiation, suggesting that the final borosilicate glass structures were quenched from a high temperature state. In addition, a sharp increase in the concentration of three membered silica rings and the presence of large amounts of penta- and hexacoordinate aluminum in the irradiated 6-oxide glass suggest that the irradiated glass is different from a liquid quenched at equilibrium, but it is rather obtained from a nonequilibrium liquid that is partially relaxed by very rapid quenching within the ion tracks

  19. Reconstruction of ancestral RNA sequences under multiple structural constraints

    Directory of Open Access Journals (Sweden)

    Olivier Tremblay-Savard

    2016-11-01

    Full Text Available Abstract Background Secondary structures form the scaffold of multiple sequence alignment of non-coding RNA (ncRNA families. An accurate reconstruction of ancestral ncRNAs must use this structural signal. However, the inference of ancestors of a single ncRNA family with a single consensus structure may bias the results towards sequences with high affinity to this structure, which are far from the true ancestors. Methods In this paper, we introduce achARNement, a maximum parsimony approach that, given two alignments of homologous ncRNA families with consensus secondary structures and a phylogenetic tree, simultaneously calculates ancestral RNA sequences for these two families. Results We test our methodology on simulated data sets, and show that achARNement outperforms classical maximum parsimony approaches in terms of accuracy, but also reduces by several orders of magnitude the number of candidate sequences. To conclude this study, we apply our algorithms on the Glm clan and the FinP-traJ clan from the Rfam database. Conclusions Our results show that our methods reconstruct small sets of high-quality candidate ancestors with better agreement to the two target structures than with classical approaches. Our program is freely available at: http://csb.cs.mcgill.ca/acharnement .

  20. Structural integrity analysis of an INPP building under external loading

    International Nuclear Information System (INIS)

    Dundulis, G.; Karalevicius, R.; Uspuras, E.; Kulak, R.F.; Marchertas, A.

    2005-01-01

    After the terrorist attacks in New York and Washington D. C. using civil airplanes, the evaluation of civil airplane crashes into civil and NPP structures has become very important. The interceptions of many terrorists' communications reveal that the use of commandeered commercial aircraft is still a major part of their plans for destruction. Aircraft crash or other flying objects in the territory of the Ignalina Nuclear Power Plant (INPP) represents a concern to the plant. Aircraft traveling at high velocity have a destructive potential. The aircraft crash may damage the roof and walls of buildings, pipelines, electric motors, cases of power supplies, power cables of electricity transmission and other elements and systems, which are important for safety. Therefore, the evaluation of the structural response to an of aircraft crash is important and was selected for analysis. The structural integrity analysis due to the effects of an aircraft crash on an NPP building structure is the subject of this paper. The finite element method was used for the structural analysis of a typical Ignalina NPP building. The structural integrity analysis was performed for a portion of the ALS using the dynamic loading of an aircraft crash impact model. The computer code NEPTUNE was used for this analysis. The local effects caused by impact of the aircraft's engine on the building wall were evaluated independently by using an empirical formula. (authors)

  1. Training set optimization under population structure in genomic selection.

    Science.gov (United States)

    Isidro, Julio; Jannink, Jean-Luc; Akdemir, Deniz; Poland, Jesse; Heslot, Nicolas; Sorrells, Mark E

    2015-01-01

    Population structure must be evaluated before optimization of the training set population. Maximizing the phenotypic variance captured by the training set is important for optimal performance. The optimization of the training set (TRS) in genomic selection has received much interest in both animal and plant breeding, because it is critical to the accuracy of the prediction models. In this study, five different TRS sampling algorithms, stratified sampling, mean of the coefficient of determination (CDmean), mean of predictor error variance (PEVmean), stratified CDmean (StratCDmean) and random sampling, were evaluated for prediction accuracy in the presence of different levels of population structure. In the presence of population structure, the most phenotypic variation captured by a sampling method in the TRS is desirable. The wheat dataset showed mild population structure, and CDmean and stratified CDmean methods showed the highest accuracies for all the traits except for test weight and heading date. The rice dataset had strong population structure and the approach based on stratified sampling showed the highest accuracies for all traits. In general, CDmean minimized the relationship between genotypes in the TRS, maximizing the relationship between TRS and the test set. This makes it suitable as an optimization criterion for long-term selection. Our results indicated that the best selection criterion used to optimize the TRS seems to depend on the interaction of trait architecture and population structure.

  2. Reconstruction of ancestral RNA sequences under multiple structural constraints.

    Science.gov (United States)

    Tremblay-Savard, Olivier; Reinharz, Vladimir; Waldispühl, Jérôme

    2016-11-11

    Secondary structures form the scaffold of multiple sequence alignment of non-coding RNA (ncRNA) families. An accurate reconstruction of ancestral ncRNAs must use this structural signal. However, the inference of ancestors of a single ncRNA family with a single consensus structure may bias the results towards sequences with high affinity to this structure, which are far from the true ancestors. In this paper, we introduce achARNement, a maximum parsimony approach that, given two alignments of homologous ncRNA families with consensus secondary structures and a phylogenetic tree, simultaneously calculates ancestral RNA sequences for these two families. We test our methodology on simulated data sets, and show that achARNement outperforms classical maximum parsimony approaches in terms of accuracy, but also reduces by several orders of magnitude the number of candidate sequences. To conclude this study, we apply our algorithms on the Glm clan and the FinP-traJ clan from the Rfam database. Our results show that our methods reconstruct small sets of high-quality candidate ancestors with better agreement to the two target structures than with classical approaches. Our program is freely available at: http://csb.cs.mcgill.ca/acharnement .

  3. Thermal structure and flow patterns around Seychelles group of Islands (Indian Ocean) during austral autumn

    Digital Repository Service at National Institute of Oceanography (India)

    Vethamony, P.; RameshBabu, V.; RameshKumar, M.R.

    Properties of thermal structure in the upper 750 m around the Seychelles group of islands in the Indian Ocean, based on Expendable Bathythermograph (XBT) data collected in March 1984, are presented along with the inferred flow patterns...

  4. Constraints on dark matter particles charged under a hidden gauge group from primordial black holes

    International Nuclear Information System (INIS)

    Dai, De-Chang; Stojkovic, Dejan; Freese, Katherine

    2009-01-01

    In order to accommodate increasingly tighter observational constraints on dark matter, several models have been proposed recently in which dark matter particles are charged under some hidden gauge group. Hidden gauge charges are invisible for the standard model particles, hence such scenarios are very difficult to constrain directly. However black holes are sensitive to all gauge charges, whether they belong to the standard model or not. Here, we examine the constraints on the possible values of the dark matter particle mass and hidden gauge charge from the evolution of primordial black holes. We find that the existence of the primordial black holes with reasonable mass is incompatible with dark matter particles whose charge to mass ratio is of the order of one. For dark matter particles whose charge to mass ratio is much less than one, we are able to exclude only heavy dark matter in the mass range of 10 11 GeV–10 16 GeV. Finally, for dark matter particles whose charge to mass ratio is much greater than one, there are no useful limits coming from primordial black holes

  5. Does the interpersonal model apply across eating disorder diagnostic groups? A structural equation modeling approach.

    Science.gov (United States)

    Ivanova, Iryna V; Tasca, Giorgio A; Proulx, Geneviève; Bissada, Hany

    2015-11-01

    Interpersonal model has been validated with binge-eating disorder (BED), but it is not yet known if the model applies across a range of eating disorders (ED). The goal of this study was to investigate the validity of the interpersonal model in anorexia nervosa (restricting type; ANR and binge-eating/purge type; ANBP), bulimia nervosa (BN), BED, and eating disorder not otherwise specified (EDNOS). Data from a cross-sectional sample of 1459 treatment-seeking women diagnosed with ANR, ANBP, BN, BED and EDNOS were examined for indirect effects of interpersonal problems on ED psychopathology mediated through negative affect. Findings from structural equation modeling demonstrated the mediating role of negative affect in four of the five diagnostic groups. There were significant, medium to large (.239, .558), indirect effects in the ANR, BN, BED and EDNOS groups but not in the ANBP group. The results of the first reverse model of interpersonal problems as a mediator between negative affect and ED psychopathology were nonsignificant, suggesting the specificity of these hypothesized paths. However, in the second reverse model ED psychopathology was related to interpersonal problems indirectly through negative affect. This is the first study to find support for the interpersonal model of ED in a clinical sample of women with diverse ED diagnoses, though there may be a reciprocal relationship between ED psychopathology and relationship problems through negative affect. Negative affect partially explains the relationship between interpersonal problems and ED psychopathology in women diagnosed with ANR, BN, BED and EDNOS. Interpersonal psychotherapies for ED may be addressing the underlying interpersonal-affective difficulties, thereby reducing ED psychopathology. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Effect of biocompatible polymers on the structural integrity of lipid bilayers under external stimuli

    Science.gov (United States)

    Wang, Jia-Yu; Kausik, Ravinath; Chen, Chi-Yuan; Han, Song-I.; Marks, Jeremy; Lee, Ka Yee

    2010-03-01

    Cell membrane dysfunction due to loss of structural integrity is the pathology of tissue death in trauma and common diseases. It is now established that certain biocompatible polymers, such as Poloxamer 188, Poloxamine 1107 and polyethylene glycol (PEG), are effective in sealing of injured cell membranes, and able to prevent acute necrosis. Despite these broad applications of these polymers for human health, the fundamental mechanisms by which these polymers interact with cell membranes are still under debate. Here, the effects of a group of biocompatible polymers on phospholipid membrane integrity under osmotic and oxidative stress were explored using giant unilamellar vesicles as model cell membranes. Our results suggest that the adsorption of the polymers on the membrane surface is responsible for the cell membrane resealing process due to its capability of slowing down the surface hydration dynamics.

  7. Insights into soybean transcriptome reconfiguration under hypoxic stress: Functional, regulatory, structural, and compositional characterization

    Science.gov (United States)

    Rodrigues, Fabiana A.; Neumaier, Norman; Marcolino-Gomes, Juliana; Molinari, Hugo B. C.; Santiago, Thaís R.; Formighieri, Eduardo F.; Basso, Marcos F.; Farias, José R. B.; Emygdio, Beatriz M.; de Oliveira, Ana C. B.; Campos, Ângela D.; Borém, Aluízio; Harmon, Frank G.; Mertz-Henning, Liliane M.; Nepomuceno, Alexandre L.

    2017-01-01

    Soybean (Glycine max) is one of the major crops worldwide and flooding stress affects the production and expansion of cultivated areas. Oxygen is essential for mitochondrial aerobic respiration to supply the energy demand of plant cells. Because oxygen diffusion in water is 10,000 times lower than in air, partial (hypoxic) or total (anoxic) oxygen deficiency is important component of flooding. Even when oxygen is externally available, oxygen deficiency frequently occurs in bulky, dense or metabolically active tissues such as phloem, meristems, seeds, and fruits. In this study, we analyzed conserved and divergent root transcriptional responses between flood-tolerant Embrapa 45 and flood-sensitive BR 4 soybean cultivars under hypoxic stress conditions with RNA-seq. To understand how soybean genes evolve and respond to hypoxia, stable and differentially expressed genes were characterized structurally and compositionally comparing its mechanistic relationship. Between cultivars, Embrapa 45 showed less up- and more down-regulated genes, and stronger induction of phosphoglucomutase (Glyma05g34790), unknown protein related to N-terminal protein myristoylation (Glyma06g03430), protein suppressor of phyA-105 (Glyma06g37080), and fibrillin (Glyma10g32620). RNA-seq and qRT-PCR analysis of non-symbiotic hemoglobin (Glyma11g12980) indicated divergence in gene structure between cultivars. Transcriptional changes for genes in amino acids and derivative metabolic process suggest involvement of amino acids metabolism in tRNA modifications, translation accuracy/efficiency, and endoplasmic reticulum stress in both cultivars under hypoxia. Gene groups differed in promoter TATA box, ABREs (ABA-responsive elements), and CRT/DREs (C-repeat/dehydration-responsive elements) frequency. Gene groups also differed in structure, composition, and codon usage, indicating biological significances. Additional data suggests that cis-acting ABRE elements can mediate gene expression independent of ABA

  8. Response of structural elements under non-uniformly distributed dynamic loads

    NARCIS (Netherlands)

    Westerhof, T.A.T.; Huebner, M.; Ferretti, D.L.; Doormaal, J.C.A.M. van; Gebbeken, N.

    2016-01-01

    Determination of the structural response of a structural element under blast loading is of interest to vulnerability / lethality (V/L) studies of military operations in urban terrain. These studies require a quick and easy to use method to simulate the structural response of e.g. a wall under

  9. Modeling of fracture of protective concrete structures under impact loads

    Science.gov (United States)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-10-01

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  10. The cortical topography of tonal structures underlying Western music.

    Science.gov (United States)

    Janata, Petr; Birk, Jeffrey L; Van Horn, John D; Leman, Marc; Tillmann, Barbara; Bharucha, Jamshed J

    2002-12-13

    Western tonal music relies on a formal geometric structure that determines distance relationships within a harmonic or tonal space. In functional magnetic resonance imaging experiments, we identified an area in the rostromedial prefrontal cortex that tracks activation in tonal space. Different voxels in this area exhibited selectivity for different keys. Within the same set of consistently activated voxels, the topography of tonality selectivity rearranged itself across scanning sessions. The tonality structure was thus maintained as a dynamic topography in cortical areas known to be at a nexus of cognitive, affective, and mnemonic processing.

  11. Study of the structure of PyHReO4 under high pressure

    International Nuclear Information System (INIS)

    Kichanov, S. E.; Kozlenko, D. P.; Wasicki, J. W.; Czarnecki, P.; Glazkov, V. P.; Nawrocik, W.; Savenko, B. N.; Lathe, C.

    2007-01-01

    The structure of deuterated pyridinium perrhenate (d 5 PyH)ReO 4 (C 5 D 5 NHReO 4 ) is studied by X-ray diffraction at room temperature and pressures up to 3.5 GPa and by neutron diffraction in the temperature range 10-293 K and at pressures up to 2.0 GPa. Under normal conditions, this compound belongs to the orthorhombic space group Cmc2 1 (ferroelectric phase II). At room temperature and pressures above P > 0.7 GPa, a transition to an orthorhombic phase (paraelectric phase II) is observed. This paraelectric phase is described by the space group Cmcm. At a pressure as high as P = 2.0 GPa, phase I remains stable at temperatures down to 10 K. This fact indicates that the high pressure suppresses the ferroelectric state in deuterated pyridinium perrhenate (d 5 PyH)ReO 4

  12. Stochastic generation of complex crystal structures combining group and graph theory with application to carbon

    Science.gov (United States)

    Shi, Xizhi; He, Chaoyu; Pickard, Chris J.; Tang, Chao; Zhong, Jianxin

    2018-01-01

    A method is introduced to stochastically generate crystal structures with defined structural characteristics. Reasonable quotient graphs for symmetric crystals are constructed using a random strategy combined with space group and graph theory. Our algorithm enables the search for large-size and complex crystal structures with a specified connectivity, such as threefold sp2 carbons, fourfold sp3 carbons, as well as mixed sp2-sp3 carbons. To demonstrate the method, we randomly construct initial structures adhering to space groups from 75 to 230 and a range of lattice constants, and we identify 281 new sp3 carbon crystals. First-principles optimization of these structures show that most of them are dynamically and mechanically stable and are energetically comparable to those previously proposed. Some of the new structures can be considered as candidates to explain the experimental cold compression of graphite.

  13. Interevent relationships and judgment under uncertainty: Structure determines strategy

    NARCIS (Netherlands)

    Sanfey, A.G.; Hastie, R.

    2002-01-01

    A fundamental empirical question regarding judgments about events is whether experienced absolute frequencies or relative. frequencies are relied on when the likelihood of a particular occurrence is judged. The present research explicates the conditions under which people rely on remembered raw

  14. Influence of amendments on soil structure and soil loss under ...

    African Journals Online (AJOL)

    Macromolecule polymers are significant types of chemical amendments because of their special structure, useful functions and low cost. Macromolecule polymers as soil amendment provide new territory for studying China's agricultural practices and for soil and water conservation, because polymers have the ability to ...

  15. Structural performance of HEPA filters under simulated tornado conditions

    International Nuclear Information System (INIS)

    Horak, H.L.; Gregory, W.S.; Ricketts, C.I.; Smith, P.R.

    1982-02-01

    This report contains the results of structural tests to determine the response of High Efficiency Particulate Air filters to simulated tornado conditions. The data include the structural limits of the filters, their resistance at high flow rates, and the effects of filter design features and tornado parameters. Considering all the filters tested, the mean break pressure or structural limit was found to be 2.35 pse (16.2 kPa). The maximum value was 2.87 psi (19.8 kPa), and the low value found was 1.31 psi (9.0 kPa). The type of failure was usually a medium break of the downstream filter fold. The type of filters that were evaluated were nuclear grade with design flow rates of 1000 cfm (0.472 m 3 /s), standard separators, and folded medium design. The parameters evaluated that are characteristic of the filter included manufacturer, separator type, faceguards, pack tightness, and aerosol loading. Manufacturer and medium properties were found to have a large effect on the structural limits

  16. Structure Formation of Thermoresponsive Microgels Suspensions Under Shear Flow

    NARCIS (Netherlands)

    Stieger, M.A.; Lindner, P.; Richtering, W.

    2004-01-01

    Shear-induced structures of concentrated temperature-sensitive poly(N-isopropylacrylamide) (PNiPAM) microgel suspensions have been studied employing small angle neutron scattering (rheo-SANS). The interaction potential of swollen PNiPAM microgels could be varied from repulsive at temperatures below

  17. Sustainability assessment of concrete structure durability under reinforcement corrosion

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie A.; Michel, Alexander; Stang, Henrik

    In the present paper a parametric study is conducted based on an existing finite element based model. The influence of cover layer, reinforcement diameter and water-to-cement ratio is compared to a possible scatter in the results due to insufficient knowledge about the distribution of the corrosi...... and predict the durability of a given structure....

  18. Optimization and anti-optimization of structures under uncertainty

    National Research Council Canada - National Science Library

    Elishakoff, Isaac; Ohsaki, Makoto

    2010-01-01

    ..., architecture, civil, mechanical or ocean engineering, invariably adopt the either/or style. Namely, they devote themselves either to linear or to nonlinear analysis of the structure they are dealing with, they are engaged in analyzing it either in the elastic or in the inelastic range; they deal either with its static or with its dynamic behavior. Al...

  19. Occupational structure in the Czech lands under the second serfdom

    Czech Academy of Sciences Publication Activity Database

    Klein, Alexander; Ogilvie, S.

    2016-01-01

    Roč. 69, č. 2 (2016), s. 493-521 ISSN 0013-0117 R&D Projects: GA ČR GA13-13848S Institutional support: RVO:67985998 Keywords : occupational structure * Czech lands * Bohemia Subject RIV: AH - Economics OBOR OECD: Applied Economics, Econometrics Impact factor: 1.233, year: 2016

  20. Adjoint Techniques for Topology Optimization of Structures Under Damage Conditions

    Science.gov (United States)

    Akgun, Mehmet A.; Haftka, Raphael T.

    2000-01-01

    The objective of this cooperative agreement was to seek computationally efficient ways to optimize aerospace structures subject to damage tolerance criteria. Optimization was to involve sizing as well as topology optimization. The work was done in collaboration with Steve Scotti, Chauncey Wu and Joanne Walsh at the NASA Langley Research Center. Computation of constraint sensitivity is normally the most time-consuming step of an optimization procedure. The cooperative work first focused on this issue and implemented the adjoint method of sensitivity computation (Haftka and Gurdal, 1992) in an optimization code (runstream) written in Engineering Analysis Language (EAL). The method was implemented both for bar and plate elements including buckling sensitivity for the latter. Lumping of constraints was investigated as a means to reduce the computational cost. Adjoint sensitivity computation was developed and implemented for lumped stress and buckling constraints. Cost of the direct method and the adjoint method was compared for various structures with and without lumping. The results were reported in two papers (Akgun et al., 1998a and 1999). It is desirable to optimize topology of an aerospace structure subject to a large number of damage scenarios so that a damage tolerant structure is obtained. Including damage scenarios in the design procedure is critical in order to avoid large mass penalties at later stages (Haftka et al., 1983). A common method for topology optimization is that of compliance minimization (Bendsoe, 1995) which has not been used for damage tolerant design. In the present work, topology optimization is treated as a conventional problem aiming to minimize the weight subject to stress constraints. Multiple damage configurations (scenarios) are considered. Each configuration has its own structural stiffness matrix and, normally, requires factoring of the matrix and solution of the system of equations. Damage that is expected to be tolerated is local

  1. The electronic structure of core states under extreme compressions

    International Nuclear Information System (INIS)

    Straub, G.K.

    1992-01-01

    At normal density and for modest compressions, the electronic structure of a metal can be accurately described by treating the conduction electrons and their interactions with the usual methods of band theory. The core electrons remain essentially the same as for an isolated free atom and do not participate in the bonding forces responsible for creating a condensed phase. As the density increases, the core electrons begin to ''see'' one another as the overlap of the tails of wave functions can no longer be neglected. The electronic structure of the core electrons is responsible for an effective repulsive interaction that eventually becomes free-electron-like at very high compressions. The electronic structure of the interacting core electrons may be treated in a simple manner using the Atomic Surface Method (ASM). The ASM is a first-principles treatment of the electronic structure involving a rigorous integration of the Schroedinger equation within the atomic-sphere approximation. Solid phase wave functions are constructed from isolated atom wave functions and the band width W l and the center of gravity of the band C l are obtained from simple formulas. The ASM can also utilize analytic forms of the atomic wave functions and thus provide direct functional dependence of various aspects of the electronic structure. Of particular use in understanding the behavior of the core electrons, the ASM provides the ability to analytically determine the density dependence of the band widths and positions. The process whereby core states interact with one another is best viewed as the formation of narrow electron bands formed from atomic states. As the core-core overlap increases, the bands increase in width and mean energy. In Sec.3 this picture is further developed and from the ASM one obtains the analytic dependence on density of the relative motion of the different bands. Also in Sec. 3 is a discussion of the transition to free electron bands

  2. African American and European American Students' Peer Groups during Early Adolescence: Structure, Status, and Academic Achievement

    Science.gov (United States)

    Wilson, Travis; Karimpour, Ramin; Rodkin, Philip C.

    2011-01-01

    Focusing on a sample of 382 African American (206 female) and 264 European American (132 female) students in diverse fourth and fifth grade classrooms, this study investigated three questions concerning the connections between peer groups and academic achievement during early adolescence: (a) How is group structure (i.e., hierarchy and cohesion)…

  3. Case Study: Improving Laboratory Learning through Group Working and Structured Reflection and Discussion.

    Science.gov (United States)

    Nicol, David J.; And Others

    1994-01-01

    Describes how student learning from a series of laboratory practicals was improved using small group methods and a structured learning cycle that encouraged reflection on group performance and investigative techniques. Discussion includes evaluation of learning benefits by means of written records, a questionnaire, observation, and the role of…

  4. Eliciting Reciprocal Peer-Tutoring Groups' Metacognitive Regulation through Structuring and Problematizing Scaffolds

    Science.gov (United States)

    De Backer, Liesje; Van Keer, Hilde; Valcke, Martin

    2016-01-01

    The study examines whether structuring (SS) versus problematising scaffolds (PS) differently affect reciprocal peer-tutoring (RPT) groups' adoption of particular regulation skills, deep-level regulation, and tutee-initiated regulation. A quasi-experimental design involving two experimental groups (SS versus PS condition) was adopted. The first,…

  5. The Effectiveness of Mindfulness-Based Group Cognitive Therapy in Reducing Depression and Obsessive Rumination among Women under Methadone Treatment

    Directory of Open Access Journals (Sweden)

    S taimory

    2015-09-01

    Full Text Available Objective: The present study was an attempt to examine the effectiveness of mindfulness-based group cognitive therapy in reducing depression and obsessive rumination among women under methadone treatment. Method: A quasi-experimental research design along with pretest-posttest design and a control group were employed to conduct this study. Considering inclusion criteria, a total of 24 female substance abusers who were under methadone treatment were selected from Omide Farda and Javeneh Sabz clinics in Mashhad via purposive sampling method. The experimental group received eight training sessions of mindfulness-based group cognitive therapy, while the control group did not receive any intervention. Two scales, namely obsessive rumination scale and Beck’s depression questionnaire were used for data collection purposes. Results: Results of analysis of covariance showed that mindfulness-based group cognitive therapy has reduced obsessive rumination and depression scores. Conclusion: Mindfulness-based group cognitive therapy can be included in intervention programs for substance abusers.

  6. Diversity, mobility, and structural and functional evolution of group II introns carrying an unusual 3' extension

    OpenAIRE

    Tourasse, Nicolas J; Stabell, Fredrik B; Kolstø, Anne-Brit

    2011-01-01

    Background Group II introns are widespread genetic elements endowed with a dual functionality. They are catalytic RNAs (ribozymes) that are able of self-splicing and they are also mobile retroelements that can invade genomic DNA. The group II intron RNA secondary structure is typically made up of six domains. However, a number of unusual group II introns carrying a unique extension of 53-56 nucleotides at the 3' end have been identified previously in bacteria of the Bacillu...

  7. Molecules and Models The molecular structures of main group element compounds

    CERN Document Server

    Haaland, Arne

    2008-01-01

    This book provides a systematic description of the molecular structures and bonding in simple compounds of the main group elements with particular emphasis on bond distances, bond energies and coordination geometries. The description includes the structures of hydrogen, halogen and methyl derivatives of the elements in each group, some of these molecules are ionic, some polar covalent. The survey of molecules whose structures conform to well-established trends is followed byrepresentative examples of molecules that do not conform. We also describe electron donor-acceptor and hydrogen bonded co

  8. Structural stability and theoretical strength of Cu crystal under equal ...

    Indian Academy of Sciences (India)

    The results indicate that, under sufficient tension, there exists a stress-free BCC phase which is unstable and slips spontaneously to a stress-free metastable BCT phase by consuming internal energy. The stable region ranges from −15.131 GPa to 2.803 GPa in the theoretical strength or from −5.801% to 4.972% in the strain ...

  9. Optimal Design of Composite Structures Under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Marmaras, Konstantinos

    sequence of well–posed optimization problems. They provide us with a discrete feasible solution or correctly determine problem infeasibility. Our aim is to solve the considered problems to proven global optimality. We propose a combination of the convergent Outer Approximation and Local Branching......This thesis considers discrete multi material and thickness optimization of laminated composite structures including local failure criteria and manufacturing constraints. Our models closely follow an immediate extension of the Discrete Material Optimization scheme, which allows simultaneous...... determination of the appropriate laminate thickness and the material choice in the structure. The optimal design problems that arise are stated as nonconvex mixed integer programming problems. We resort to different reformulation techniques to state the optimization problems as either linear or nonlinear convex...

  10. Analysis of ADU structure obtained under different precipitation conditions

    International Nuclear Information System (INIS)

    Ramella, Jose L.; Esteban, Adolfo; Mendez De Leo, Lucia P.; Sassone, Ariel; Novara, Oscar E.; Boero, Norma L.; Leyva, Ana G.

    1999-01-01

    ADU is the nominal name for ammonium poly uranate. It is a very complex compound of polymeric structure, which may have, according to precipitation conditions, different chemical composition and crystallographic structure. ADU is used as uranium oxide precursor in the manufacture of fuel elements. In former papers it was proved that if ultrasound is applied during precipitation and digestion the characteristics of the final product (U 3 O 8 UO 2 ) improve. By studying ADU thermal decomposition obtained by ultrasonic application, it was intended to obtain its composition. Therefore, differential thermal gravimetric and differential thermal analyses were performed. Samples were taken from special points and analyzed by X-ray diffraction, infra-red spectroscopy and scanning. An experiment was also designed to identify the products released during heating. Results and conclusions obtained are presented in this work. (author)

  11. Fiscal reaction under endogenous structural changes in Brazil

    Directory of Open Access Journals (Sweden)

    Andrei G. Simonassi

    2014-01-01

    Full Text Available Regarding the importance of fiscal policy in smoothing the impact of shocks such as the international financial and economic crises, the paper analyzes the sustainability of the Brazilian fiscal policy by taking into consideration the possibility of multiple endogenous structural breaks on the coefficients of government reaction function. From monthly data in the period 1991–2008, tests on the reliable estimates dictate the occurrence of structural change in May 1994, and another in February 2003. There has been a situation of fiscal solvency in Brazil, but only from May 1994 the hitherto innocuous actions of government to formulate policies on public debt turn out to be significant, as it rose twofold after February 2003. This reinforces the existence of a more flexible alternative to implement strategic policy in Brazil, if an eventual alternative for increasing public spending is a way of hindering the effects of international financial crises without compromising the fiscal targets.

  12. Structural optimization under overhang constraints imposed by additive manufacturing technologies

    Science.gov (United States)

    Allaire, G.; Dapogny, C.; Estevez, R.; Faure, A.; Michailidis, G.

    2017-12-01

    This article addresses one of the major constraints imposed by additive manufacturing processes on shape optimization problems - that of overhangs, i.e. large regions hanging over void without sufficient support from the lower structure. After revisiting the 'classical' geometric criteria used in the literature, based on the angle between the structural boundary and the build direction, we propose a new mechanical constraint functional, which mimics the layer by layer construction process featured by additive manufacturing technologies, and thereby appeals to the physical origin of the difficulties caused by overhangs. This constraint, as well as some variants, is precisely defined; their shape derivatives are computed in the sense of Hadamard's method, and numerical strategies are extensively discussed, in two and three space dimensions, to efficiently deal with the appearance of overhang features in the course of shape optimization processes.

  13. Structure and morphology of mythimna pupa under diffraction enhanced imaging

    International Nuclear Information System (INIS)

    Huang Wanxia; Yuan Qingxi; Zhu Peiping; Wang Junyue; Liu Yijin; Chen Bo; Shu Hang; Hu Tiandou; Wu Ziyu; Ge Siqin

    2007-01-01

    As a technique of X-ray phase contrast imaging, the diffraction enhanced imaging (DEI) attracts much interest due to its high resolution and contrast. The top images of DEI were used to study the growth of a complete metamorphic mythimna in the period of pupa. Clear images about the pupa structure were obtained. The entire growth process of the pupa was observed, including the evolvement of part of organs and tissues from larva to imago. (authors)

  14. Structural performance of HEPA filters under simulated tornado conditions

    Science.gov (United States)

    Horak, H. L.; Gregory, W. S.; Ricketts, C. I.; Smith, P. R.

    1982-02-01

    The response of high efficiency particulate air filters to simulated tornado conditions was determined. The data include the structural limits of the filters, their resistance at high flow rates, and the effects of filter design features and tornado parameters. Considering all the filters tested, the mean break pressure or structural limit was found to be 2.35 pse (16.2 kPa). The maximum value was 2.87 psi (19.8 kPa), and the low value found was 1.31 psi (9.0 kPa). The type of failure was usually a medium break of the downstream filter fold. The types of filters that were evaluated were nuclear grade with design flow rates of 1000 cfm (0.472 cu m/s), standard separators, and folded medium design. The parameters evaluated that are characteristic of the filter included manufacturer, separator type, face-guards, pack tightness, and aerosol loading. Manufacturer and medium properties were found to have a large effect on the structural limits.

  15. Disrupted white matter structure underlies cognitive deficit in hypertensive patients

    International Nuclear Information System (INIS)

    Li, Xin; Ma, Chao; Zhang, Junying; Chen, Yaojing; Zhang, Zhanjun; Sun, Xuan; Chen, Kewei

    2016-01-01

    Hypertension is considered a risk factor of cognitive impairments and could result in white matter changes. Current studies on hypertension-related white matter (WM) changes focus only on regional changes, and the information about global changes in WM structure network is limited. We assessed the cognitive function in 39 hypertensive patients and 37 healthy controls with a battery of neuropsychological tests. The WM structural networks were constructed by utilizing diffusion tensor tractography and calculated topological properties of the networks using a graph theoretical method. The direct and indirect correlations among cognitive impairments, brain WM network disruptions and hypertension were analyzed with structural equation modelling (SEM). Hypertensive patients showed deficits in executive function, memory and attention compared with controls. An aberrant connectivity of WM networks was found in the hypertensive patients (P Eglob = 0.005, P Lp = 0.005), especially in the frontal and parietal regions. Importantly, SEM analysis showed that the decline of executive function resulted from aberrant WM networks in hypertensive patients (p = 0.3788, CFI = 0.99). These results suggest that the cognitive decline in hypertensive patients was due to frontal and parietal WM disconnections. Our findings highlight the importance of brain protection in hypertension patients. (orig.)

  16. The Response of Simple Polymer Structures Under Dynamic Loading

    Science.gov (United States)

    Proud, William; Ellison, Kay; Yapp, Su; Cole, Cloe; Galimberti, Stefano; Institute of Shock Physics Team

    2017-06-01

    The dynamic response of polymeric materials has been widely studied with the effects of degree of crystallinity, strain rate, temperature and sample size being commonly reported. This study uses a simple PMMA structure, a right cylindrical sample, with structural features such as holes. The features are added an varied in a systematic fashion. Samples were dynamically loaded using a Split Hopkinson Pressure Bar up to failure. The resulting stress-strain curves are presented showing the change in sample response. The strain to failure is shown to increase initially with the presence of holes, while failure stress is relatively unaffected. The fracture patterns seen in the failed samples change, with tensile cracks, Hertzian cones, shear effects being dominant for different holes sizes and geometries. The sample were prepared by laser cutting and checked for residual stress before experiment. The data is used to validate predictive model predictions where material, structure and damage are included.. The Institute of Shock Physics acknowledges the support of Imperial College London and the Atomic Weapons Establishment.

  17. THE RELATIONSHIP BETWEEN INDUSTRIAL PRODUCTION AND EMPLOYMENT UNDER STRUCTURAL BREAK

    Directory of Open Access Journals (Sweden)

    Umut HALAÇ

    2017-12-01

    Full Text Available For the economies which aim for the sustainable economic growth, one of the most important topic is industrialization. It is thought that it effects employability positively, by increasing the manufacturing. This study investigates the long-term relationship between industrial production and total employment, industrial employment and youth employment in Turkey using monthly data for the period from 2005:01 to 2017:06. Since the period involving structural changes, the stability of series was tested by standart Augmented Dickey Fuller unit root test and Zivot Andrews unit root test with structural breaks. Estimates of the cointegrating relation are obtained using Engle-Granger test procedure and Gregory Hansen test procedure taking structural breaks into account. The results of cointegration tests show that there is no long run relationship among the variables. The findings of the study indicate that the connections between industrial production and employment have been disappeared, during the time period examined for Turkey. This also suggests that the rise in the industrial production is still far from creating employability.

  18. Term Structure of Credit Spreads of A Firm When Its Underlying Assets are Discontinuous

    Directory of Open Access Journals (Sweden)

    Budhi Arta Surya

    2012-01-01

    Full Text Available We revisit the previous works of Leland [12], Leland and Toft [11] andHilberink and Rogers [7] on optimal capital structure and show that thecredit spreads of short-maturity corporate bonds can have nonzero valueswhen the underlying of the firm’s assets value has downward jumps. We givean analytical treatment of this fact under a general Levy process and discusssome numerical examples under pure jump processes.Keywords: Optimal capital structure, credit risk, term structure of creditspread

  19. A general formula considering one group delayed neutron under nonequilibrium condition

    International Nuclear Information System (INIS)

    Li Haofeng; Chen Wenzhen; Zhu Qian; Luo Lei

    2008-01-01

    A general neutron breeder formula is developed when the reactor does not reach the steady state and the reactivity changes in phase. This formula can be used to calculate the results of six groups delayed neutron model through a way of amending λ in one group delayed neutron model. The analysis shows that the solution of amended single group delayed neutron model is approximately equal to that of six-group delayed neutron model, and the amended model meets the engineering accuracy. (authors)

  20. An Analysis of Small Group Interactions of Vietnamese Students under the Bourdieusian Theoretical Lens

    Science.gov (United States)

    Pham, Thanh; Pham, Lam

    2018-01-01

    Group work has been increasingly encouraged and applied in Vietnamese universities. However, very little has been known about how Vietnamese university students work in a group and what the conditions are that help establish an effective group. This study attempted to redress this gap. The research applied Bourdieu's social field theory to examine…

  1. Structural modification of aluminium oxynitride phases under stresses at high temperatures, high pressures and under irradiation by fast neutrons

    International Nuclear Information System (INIS)

    Labbe, J.C.; Jeanne, A.; Roult, G.

    1990-01-01

    The structural modifications of the aluminium oxynitride phases under stresses are studied by the time of flight neutron diffraction method, at high temperatures (up to 1375degC), at high pressures (up to 2.4 GPa), and under irradiation by fast neutrons (up to 3.2 X 10 20 n/cm 2 ). In each case the evolutions of cell parameter, interatomic bond angles, bond lengths and atomic positions are given. (orig.)

  2. Interfaith Groups as Mediating Structures for Political Action: A Multilevel Analysis.

    Science.gov (United States)

    Todd, Nathan R; Boeh, Brett A; Houston-Kolnik, Jaclyn D; Suffrin, Rachael L

    2017-03-01

    This study investigates interfaith groups from across the United States to understand how these religious settings may serve as mediating structures to facilitate individual political action. Based on a multilevel modeling analysis with 169 individuals from 25 interfaith groups, we found that core activities of the group, such as group members sharing community information (e.g., announcing upcoming events, political meetings, community issues) or sharing religious information (e.g., educating members about their religion) positively and negatively predicted individual political action as a result of group participation, respectively. Moreover, a sense that the interfaith group served as a community to work for local change, but not trust within the group, predicted political action as a result of group participation. However, this effect for a sense the group served as a community to work for local change was stronger and more positive as the degree of community information sharing in the group increased. These results show that a core activity of sharing community information may enhance the ability of a group to mediate political action. Overall, these findings demonstrate the potential role of interfaith groups to mediate political action, and show the importance of considering both individual and group characteristics when understanding these religious settings. Limitations and directions for future research are also discussed. © Society for Community Research and Action 2017.

  3. Benefits of gregarious feeding by aposematic caterpillars depend on group age structure.

    Science.gov (United States)

    Campbell, Stuart A; Stastny, Michael

    2015-03-01

    Gregarious feeding is a common feature of herbivorous insects and can range from beneficial (e.g. dilution of predation risk) to costly (e.g. competition). Group age structure should influence these costs and benefits, particularly when old and young larvae differ in their feeding mode or apparency to predators. We investigated the relative value of gregarious feeding by aposematic larvae of Uresiphita reversalis that we observed feeding in groups of mixed ages and variable densities on wild Lupinus diffusus. In a manipulative field experiment, the survivorship and growth of young larvae were enhanced in the presence of older conspecifics, but not in large groups of similarly aged larvae. Estimates of insect damage and induced plant responses suggest that mixed-age groups enhance plant quality for young larvae while avoiding competition. We conclude that benefits of gregariousness in this species are contingent on group age structure, a finding of significance for the ecology and evolution of gregariousness and other social behaviours.

  4. Structural behavior of human lumbar intervertebral disc under direct shear.

    Science.gov (United States)

    Schmidt, Hendrik; Häussler, Kim; Wilke, Hans-Joachim; Wolfram, Uwe

    2015-03-18

    The intervertebral disc (IVD) is a complex, flexible joint between adjacent vertebral bodies that provides load transmission while permitting movements of the spinal column. Finite element models can be used to help clarify why and how IVDs fail or degenerate. To do so, it is of importance to validate those models against controllable experiments. Due to missing experimental data, shear properties are not used thus far in validating finite element models. This study aimed to investigate the structural shear properties of human lumbar IVDs in posteroanterior (PA) and laterolateral (LL) loading directions. Fourteen lumbar IVDs (median age: 49 years) underwent direct shear in PA and LL loading directions. A custom-build shear device was used in combination with a materials testing machine to load the specimens until failure. Shear stiffness, ultimate shear force and displacement, and work to failure were determined. Each specimen was tested until complete or partial disruption. Median stiffness in PA direction was 490 N/mm and in LL direction 568 N/mm. Median ultimate shear force in the PA direction was 2,877 N and in the LL direction 3,199 N. Work to failure was 12 Nm in the PA and 9 Nm in the LL direction. This study was an experiment to subject IVDs to direct shear. The results could help us to understand the structure and function of IVDs with regard to mechanical spinal stability, and they can be used to validate finite element models of the IVD.

  5. Brain Events Underlying Episodic Memory Changes in Aging: A Longitudinal Investigation of Structural and Functional Connectivity.

    Science.gov (United States)

    Fjell, Anders M; Sneve, Markus H; Storsve, Andreas B; Grydeland, Håkon; Yendiki, Anastasia; Walhovd, Kristine B

    2016-03-01

    Episodic memories are established and maintained by close interplay between hippocampus and other cortical regions, but degradation of a fronto-striatal network has been suggested to be a driving force of memory decline in aging. We wanted to directly address how changes in hippocampal-cortical versus striatal-cortical networks over time impact episodic memory with age. We followed 119 healthy participants (20-83 years) for 3.5 years with repeated tests of episodic verbal memory and magnetic resonance imaging for quantification of functional and structural connectivity and regional brain atrophy. While hippocampal-cortical functional connectivity predicted memory change in young, changes in cortico-striatal functional connectivity were related to change in recall in older adults. Within each age group, effects of functional and structural connectivity were anatomically closely aligned. Interestingly, the relationship between functional connectivity and memory was strongest in the age ranges where the rate of reduction of the relevant brain structure was lowest, implying selective impacts of the different brain events on memory. Together, these findings suggest a partly sequential and partly simultaneous model of brain events underlying cognitive changes in aging, where different functional and structural events are more or less important in various time windows, dismissing a simple uni-factorial view on neurocognitive aging. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  6. Specialists’ Meeting on Demonstration of Structural Integrity under Normal and Faulted Conditions. Summary Report

    International Nuclear Information System (INIS)

    1981-03-01

    The Specialists' Meeting on ''Demonstration of Structural Integrity under Normal and Faulted Conditions'' was held at Chester, United Kingdom on 3-5 June 1980. The meeting was sponsored by the International Atomic Energy Agency (IAEA) on the recommendation of the International Working Group on Past Reactors (IWGFR). Twenty-one participants from France, the Federal Republic of Germany, Italy, Japan, the Netherlands, the United Kingdom, the United States of America and two international organizations, CEC and IAEA, attended. The purpose of the meeting was to review and discuss methods for assessing the integrity of the LMFBR safety-related structures during normal and abnormal operation, especially in the presence of defects, and to recommend future development. The technical sessions were divided into four topical sessions as follows: 1. National Review Presentations on Demonstration of Structural Integrity; 2. Material Properties; 3. Structural Analysis; 4. Design Approaches and Assessment Experience. During the meeting papers were presented by the participants on behalf of their countries or organizations. Each presentation was followed by an open discussion in the subject covered by the paper and subsequently, session summaries were drafted. After the formal sessions were completed, a final discussion session was held and general conclusions and recommendations were reached by consensus. Session summaries, general conclusions and recommendations, national review papers presented during the first session as well as the agenda of the meeting and the list of participants are given

  7. A process-oriented group model for university students: a semi-structured approach.

    Science.gov (United States)

    Johnson, Chad V

    2009-10-01

    University students present several challenges for group therapists in terms of establishing and sustaining interpersonal process groups in college counseling center settings. These challenges may result from a lack of client preparation and/or a mismatch of therapy practices with the unique developmental characteristics of today's college students. This paper discusses these developmental needs and proposes a model for successful interpersonal group therapy with university students. The proposed model encourages structured activities at the initial and final stages of a process-oriented therapy group to assist leaders and teach the members skills to promote cohesion, skill development, and interpersonal learning. This model may also be used to train novice group counselors how to facilitate here-and-now interactions in group and shape group process.

  8. Inhalation TTC values: A new integrative grouping approach considering structural, toxicological and mechanistic features.

    Science.gov (United States)

    Tluczkiewicz, I; Kühne, R; Ebert, R-U; Batke, M; Schüürmann, G; Mangelsdorf, I; Escher, S E

    2016-07-01

    The present publication describes an integrative grouping concept to derive threshold values for inhalation exposure. The classification scheme starts with differences in toxicological potency and develops criteria to group compounds into two potency classes, namely toxic (T-group) or low toxic (L-group). The TTC concept for inhalation exposure is based on the TTC RepDose data set, consisting of 296 organic compounds with 608 repeated-dose inhalation studies. Initially, 21 structural features (SFs) were identified as being characteristic for compounds of either high or low NOEC values (Schüürmann et al., 2016). In subsequent analyses these SF groups were further refined by taking into account structural homogeneity, type of toxicological effect observed, differences in absorption, metabolism and mechanism of action (MoA), to better define their structural and toxicological boundaries. Differentiation of a local or systemic mode of action did not improve the classification scheme. Finally, 28 groups were discriminated: 19 T-groups and 9 L-groups. Clearly distinct thresholds were derived for the T- and L-toxicity groups, being 2 × 10(-5) ppm (2 μg/person/day) and 0.05 ppm (4260 μg/person/day), respectively. The derived thresholds and the classification are compared to the initial mainly structure driven grouping (Schüürmann et al., 2016) and to the Cramer classification. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Structural evaluation of electrosleeved tubes under severe accident transients

    International Nuclear Information System (INIS)

    Majumdar, S.

    1999-01-01

    A flow stress model was developed for predicting failure of Electrosleeved PWR steam generator tubing under severe accident transients. The Electrosleeve, which is nanocrystalline pure nickel, loses its strength at temperatures greater than 400 C during severe accidents because of grain growth. A grain growth model and the Hall-Petch relationship were used to calculate the loss of flow stress as a function of time and temperature during the accident. Available tensile test data as well as high temperature failure tests on notched Electrosleeved tube specimens were used to derive the basic parameters of the failure model. The model was used to predict the failure temperatures of Electrosleeved tubes with axial cracks in the parent tube during postulated severe accident transients

  10. Nonequilibrium structure of colloidal dumbbells under oscillatory shear.

    Science.gov (United States)

    Heptner, Nils; Chu, Fangfang; Lu, Yan; Lindner, Peter; Ballauff, Matthias; Dzubiella, Joachim

    2015-11-01

    We investigate the nonequilibrium behavior of dense, plastic-crystalline suspensions of mildly anisotropic colloidal hard dumbbells under the action of an oscillatory shear field by employing Brownian dynamics computer simulations. In particular, we extend previous investigations, where we uncovered nonequilibrium phase transitions, to other aspect ratios and to a larger nonequilibrium parameter space, that is, a wider range of strains and shear frequencies. We compare and discuss selected results in the context of scattering and rheological experiments. Both simulations and experiments demonstrate that the previously found transitions from the plastic crystal phase with increasing shear strain also occur at other aspect ratios. We explore the transition behavior in the strain-frequency phase and summarize it in a nonequilibrium phase diagram. Additionally, the experimental rheology results hint at a slowing down of the colloidal dynamics with higher aspect ratio.

  11. Finite element modeling of Balsa wood structures under severe loadings

    International Nuclear Information System (INIS)

    Toson, B.; Pesque, J.J.; Viot, P.

    2014-01-01

    In order to compute, in various situations, the requirements for transporting packages using Balsa wood as an energy absorber, a constitutive model is needed that takes into account all of the specific characteristics of the wood, such as its anisotropy, compressibility, softening, densification, and strain rate dependence. Such a model must also include the treatment of rupture of the wood when it is in traction. The complete description of wood behavior is not sufficient: robustness is also necessary because this model has to work in presence of large deformations and of many other external nonlinear phenomena in the surrounding structures. We propose such a constitutive model that we have developed using the commercial finite element package ABAQUS. The necessary data were acquired through an extensive compilation of the existing literature with the augmentation of personal measurements. Numerous validation tests are presented that represent different impact situations that a transportation cask might endure. (authors)

  12. Structural attributes of stand overstory and light under the canopy

    Directory of Open Access Journals (Sweden)

    Alice Angelini

    2015-02-01

    Full Text Available  This paper reviews the literature relating to the relationship between light availability in the understory and the main qualitative and quantitative attributes of stand overstory usually considered in forest management and planning (species composition, density, tree sizes, etc. as well as their changes as consequences of harvesting. The paper is divided in two sections: the first one reviews studies which investigated the influence of species composition on understory light conditions; the second part examines research on the relationships among stand parameters determined from dendrometric field data and the radiation on understory layer. The objective was to highlight which are the most significant stand traits and management features to build more practical models for predicting light regimes in any forest stand and, in more general terms, to support forest managers in planning and designing silvicultural treatments that retain structure in different way in order to meet different objectives.

  13. Durability reliability analysis for corroding concrete structures under uncertainty

    Science.gov (United States)

    Zhang, Hao

    2018-02-01

    This paper presents a durability reliability analysis of reinforced concrete structures subject to the action of marine chloride. The focus is to provide insight into the role of epistemic uncertainties on durability reliability. The corrosion model involves a number of variables whose probabilistic characteristics cannot be fully determined due to the limited availability of supporting data. All sources of uncertainty, both aleatory and epistemic, should be included in the reliability analysis. Two methods are available to formulate the epistemic uncertainty: the imprecise probability-based method and the purely probabilistic method in which the epistemic uncertainties are modeled as random variables. The paper illustrates how the epistemic uncertainties are modeled and propagated in the two methods, and shows how epistemic uncertainties govern the durability reliability.

  14. Chemical Structures of Novel Maillard Reaction Products under Hyperglycemic Conditions.

    Science.gov (United States)

    Imahori, Daisuke; Matsumoto, Takahiro; Kojima, Naoto; Hasei, Tomohiro; Sumii, Megumi; Sumida, Taishi; Yamashita, Masayuki; Watanabe, Tetsushi

    2018-01-01

    Two novel and two known compounds, 4-quinolylaldoxime and indole-3-aldehyde, were isolated from a reaction mixture consisting of D-glucose and L-tryptophan at physiological temperature and pH. The chemical structures of the two novel compounds were elucidated by spectroscopic analysis such as X-ray crystallography. One of the novel compound and the indole-3-aldehyde showed mutagenicity toward Salmonella typhimurium YG1024 with S9 mix. Furthermore, 4-quinolylaldoxime was detected from streptozotocin-induced diabetic rat plasma by LC-MS/MS analysis; however, the isolated compounds were not detected in rat diet extracts. To our knowledge, this is the first report in which 4-quinolylaldoxime was detected in rat plasma. These results suggest that amino-carbonyl reaction products may be formed in diabetic condition and induce genetic damage.

  15. Issues and Practices in the Identification and Education of Gifted Students From Under-represented Groups

    Science.gov (United States)

    Borland, James

    2004-01-01

    In this monograph, I discuss the current and historic under-representation of economically disadvantaged students, students of color, students from ethnic minorities, and students with limited English proficiency in programs for gifted students. I examine the likely causes of the under-representation of these students, drawing on research and…

  16. Reliability prediction for structures under cyclic loads and recurring inspections

    Directory of Open Access Journals (Sweden)

    Alberto W. S. Mello Jr

    2009-06-01

    Full Text Available This work presents a methodology for determining the reliability of fracture control plans for structures subjected to cyclic loads. It considers the variability of the parameters involved in the problem, such as initial flaw and crack growth curve. The probability of detection (POD curve of the field non-destructive inspection method and the condition/environment are used as important factors for structural confidence. According to classical damage tolerance analysis (DTA, inspection intervals are based on detectable crack size and crack growth rate. However, all variables have uncertainties, which makes the final result totally stochastic. The material properties, flight loads, engineering tools and even the reliability of inspection methods are subject to uncertainties which can affect significantly the final maintenance schedule. The present methodology incorporates all the uncertainties in a simulation process, such as Monte Carlo, and establishes a relationship between the reliability of the overall maintenance program and the proposed inspection interval, forming a “cascade” chart. Due to the scatter, it also defines the confidence level of the “acceptable” risk. As an example, the damage tolerance analysis (DTA results are presented for the upper cockpit longeron splice bolt of the BAF upgraded F-5EM. In this case, two possibilities of inspection intervals were found: one that can be characterized as remote risk, with a probability of failure (integrity nonsuccess of 1 in 10 million, per flight hour; and other as extremely improbable, with a probability of nonsuccess of 1 in 1 billion, per flight hour, according to aviation standards. These two results are compared with the classical military airplane damage tolerance requirements.

  17. Comparison of micelle structure of glycolipids with different head groups by small angle neutron scattering

    International Nuclear Information System (INIS)

    He, Lizhong; Middelberg, Anton; Hartmann, Thorsten; Niemeyer, Bernd; Garamus, V.M.; Willumeit, Regine

    2005-01-01

    Full text: Glycolipids such as n-alkyl- beta-D-glucopyranoside and n-alkyl- beta-D-maltopyranoside can self-assemble into different structures depending on solution conditions. Their amphiphilic properties enable them to serve as biosurfactants in biology and biotechnology, especially for solubilizing membrane proteins. The physicochemical properties of glycolipids have attracted attentions from several research groups, aiming to better understand their application in biological and environmental processes. For example, small angle neutron and X-ray scattering have been used to study micelle structures formed by glycolipids. Our previous work has shown that n-octyl-beta- D-glucopyranoside and n-octyl- beta-D-maltopyranoside form micelles with different structure, suggesting an important role of the sugar head group in micelle formation. In the present work, we further compare micelle structures of n-octyl- beta-Dglucopyranoside and n-octyl- beta-D-galactopyranoside. These two glycolipids have the same hydrophobic tail and their head sugar groups differ only in the conformation with one hydroxyl group pointing to different direction. Our SANS data together with phase behaviours reported by other group have suggested that a slight alteration of head group conformation can significantly affect self-assembly of glycolipids. (authors)

  18. [The Effect of Structured Group Reminiscence Therapy on the Life Satisfaction of Institutionalized Elderly].

    Science.gov (United States)

    Chen, Shu-Mei; Kuo, Chien-Lin; Chen, Mei-Rong; Lee, Lai-Ling; Lee, Pi-Yueh; Wang, Shu-Fen

    2016-08-01

    Long-term care institutions have become an option for older people who are dependent in daily living. However, insufficient attention has been focused on assessing the life satisfaction of those currently residing in these institutions in Taiwan. Previous research indicates that group reminiscence may improve the life satisfaction of older adults. However, there is currently no consensus regarding the implementation and evaluation of reminiscence interventions. To examine the effect of a structured group reminiscence protocol on the life satisfaction of institutionalized older adults. The study used a quasi-experimental design. A total of 48 older adults were conveniently recruited from two long-term care institutions in southern Taiwan. The experimental group (n = 23) received 8 weeks of structured-group reminiscence for 40 minutes weekly, while the control group (n = 25) received routine care from the institution. Both groups were evaluated using a life-satisfaction questionnaire before and after the intervention and again four weeks later. Life satisfaction scores were statistically similar on the pre-test and significantly different on both post-test questionnaires for the two groups. The scores for the experimental and control groups were pre-test: 24.22 vs 23.36 (p = .063); post-test I: 27.22 vs 23.32 (p life satisfaction for the experimental group increased by 0.85-points (p = .042) more than the control group, which is a significant difference. The results support that the 8-week structured group reminiscence protocol effectively enhances life satisfaction in older adults. The results of this study may be referenced in the continuing education of nurses working in long-term care institutions in the context of helping nurses organize, facilitate, and evaluate this protocol.

  19. Population genetic structure of peninsular Malaysia Malay sub-ethnic groups.

    Science.gov (United States)

    Hatin, Wan Isa; Nur-Shafawati, Ab Rajab; Zahri, Mohd-Khairi; Xu, Shuhua; Jin, Li; Tan, Soon-Guan; Rizman-Idid, Mohammed; Zilfalil, Bin Alwi

    2011-04-05

    Patterns of modern human population structure are helpful in understanding the history of human migration and admixture. We conducted a study on genetic structure of the Malay population in Malaysia, using 54,794 genome-wide single nucleotide polymorphism genotype data generated in four Malay sub-ethnic groups in peninsular Malaysia (Melayu Kelantan, Melayu Minang, Melayu Jawa and Melayu Bugis). To the best of our knowledge this is the first study conducted on these four Malay sub-ethnic groups and the analysis of genotype data of these four groups were compiled together with 11 other populations' genotype data from Indonesia, China, India, Africa and indigenous populations in Peninsular Malaysia obtained from the Pan-Asian SNP database. The phylogeny of populations showed that all of the four Malay sub-ethnic groups are separated into at least three different clusters. The Melayu Jawa, Melayu Bugis and Melayu Minang have a very close genetic relationship with Indonesian populations indicating a common ancestral history, while the Melayu Kelantan formed a distinct group on the tree indicating that they are genetically different from the other Malay sub-ethnic groups. We have detected genetic structuring among the Malay populations and this could possibly be accounted for by their different historical origins. Our results provide information of the genetic differentiation between these populations and a valuable insight into the origins of the Malay sub-ethnic groups in Peninsular Malaysia.

  20. Population Genetic Structure of Peninsular Malaysia Malay Sub-Ethnic Groups

    Science.gov (United States)

    Hatin, Wan Isa; Nur-Shafawati, Ab Rajab; Zahri, Mohd-Khairi; Xu, Shuhua; Jin, Li; Tan, Soon-Guan; Rizman-Idid, Mohammed; Zilfalil, Bin Alwi

    2011-01-01

    Patterns of modern human population structure are helpful in understanding the history of human migration and admixture. We conducted a study on genetic structure of the Malay population in Malaysia, using 54,794 genome-wide single nucleotide polymorphism genotype data generated in four Malay sub-ethnic groups in peninsular Malaysia (Melayu Kelantan, Melayu Minang, Melayu Jawa and Melayu Bugis). To the best of our knowledge this is the first study conducted on these four Malay sub-ethnic groups and the analysis of genotype data of these four groups were compiled together with 11 other populations' genotype data from Indonesia, China, India, Africa and indigenous populations in Peninsular Malaysia obtained from the Pan-Asian SNP database. The phylogeny of populations showed that all of the four Malay sub-ethnic groups are separated into at least three different clusters. The Melayu Jawa, Melayu Bugis and Melayu Minang have a very close genetic relationship with Indonesian populations indicating a common ancestral history, while the Melayu Kelantan formed a distinct group on the tree indicating that they are genetically different from the other Malay sub-ethnic groups. We have detected genetic structuring among the Malay populations and this could possibly be accounted for by their different historical origins. Our results provide information of the genetic differentiation between these populations and a valuable insight into the origins of the Malay sub-ethnic groups in Peninsular Malaysia. PMID:21483678

  1. Structural Basis for the ABO Blood-Group Dependence of Plasmodium falciparum Rosetting

    Science.gov (United States)

    Hessel, Audrey; Raynal, Bertrand; England, Patrick; Cohen, Jacques H.; Bertrand, Olivier; Peyrard, Thierry; Bentley, Graham A.; Lewit-Bentley, Anita; Mercereau-Puijalon, Odile

    2012-01-01

    The ABO blood group influences susceptibility to severe Plasmodium falciparum malaria. Recent evidence indicates that the protective effect of group O operates by virtue of reduced rosetting of infected red blood cells (iRBCs) with uninfected RBCs. Rosetting is mediated by a subgroup of PfEMP1 adhesins, with RBC binding being assigned to the N-terminal DBL1α1 domain. Here, we identify the ABO blood group as the main receptor for VarO rosetting, with a marked preference for group A over group B, which in turn is preferred to group O RBCs. We show that recombinant NTS-DBL1α1 and NTS-DBL1α1-CIDR1γ reproduce the VarO-iRBC blood group preference and document direct binding to blood group trisaccharides by surface plasmon resonance. More detailed RBC subgroup analysis showed preferred binding to group A1, weaker binding to groups A2 and B, and least binding to groups Ax and O. The 2.8 Å resolution crystal structure of the PfEMP1-VarO Head region, NTS-DBL1α1-CIDR1γ, reveals extensive contacts between the DBL1α1 and CIDR1γ and shows that the NTS-DBL1α1 hinge region is essential for RBC binding. Computer docking of the blood group trisaccharides and subsequent site-directed mutagenesis localized the RBC-binding site to the face opposite to the heparin-binding site of NTS-DBLα1. RBC binding involves residues that are conserved between rosette-forming PfEMP1 adhesins, opening novel opportunities for intervention against severe malaria. By deciphering the structural basis of blood group preferences in rosetting, we provide a link between ABO blood grouppolymorphisms and rosette-forming adhesins, consistent with the selective role of falciparum malaria on human genetic makeup. PMID:22807674

  2. Structural characteristics signal-grass under continuois stoking and nitrogen fertilization

    Directory of Open Access Journals (Sweden)

    Rodrigo Vieira de Morais

    2010-01-01

    Full Text Available From February to November 2003, the mass and morphological composition of forage from Brachiaria decumbens cv. Basilisk pastures under four different doses of nitrogen (75, 150, 225 and 300 kg/ha/year were evaluated. The pastures were managed under continuous stocking with growing cattle. The data were grouped within three periods: February to April, May to August and September to November. Randomized block design with subdivided plots and two repetitions was used. The plots correspond to the nitrogen (N doses, while the subplots to the time of the evaluation. In the period from May to August, the forage mass in the B. decumbens pasture increased linearly related to the N dose. The percentage of green leaf blade (GLB was lower in the May/August period if compared to the other periods. The highest percentage values for green stem (GS ocorred February/April. The relation between LFV masses and CV were influenced by the period of evaluation, reaching higher values in September/November. When 75 kg ha-1 of N was applied, the senescent tissue (ST participation in the pasture did not vary throughout the months of the year. However, when whith doses of 150 kg ha-1 of N were applied, the percentage of ST was lower for February/April in comparison to the other periods. The percentages of GFB and GS increased linearly and positively as the N doses increased in the February/April. The structure of the B. decumbens pasture under continuous stocking is influenced interactively by the nitrogen doses and time of the year. Nitrogen fertilization improves the structure of the B. decumbens pasture under continuous stocking managed with the same mean height.

  3. Group Lifting Structures For Multirate Filter Banks, II: Linear Phase Filter Banks

    Energy Technology Data Exchange (ETDEWEB)

    Brislawn, Christopher M [Los Alamos National Laboratory

    2008-01-01

    The theory of group lifting structures is applied to linear phase lifting factorizations for the two nontrivial classes of two-channel linear phase perfect reconstruction filter banks, the whole-and half-sample symmetric classes. Group lifting structures defined for the reversible and irreversible classes of whole-and half-sample symmetric filter banks are shown to satisfy the hypotheses of the uniqueness theorem for group lifting structures. It follows that linear phase lifting factorizations of whole-and half-sample symmetric filter banks are therefore independent of the factorization methods used to compute them. These results cover the specification of user-defined whole-sample symmetric filter banks in Part 2 of the ISO JPEG 2000 standard.

  4. Summary report for MEGAPIE R+D Task Group X4: Fluid dynamics and structure mechanics

    International Nuclear Information System (INIS)

    Smith, B. L.

    2006-03-01

    The document chronicles, and draws summary conclusions from, the activities of the X4 R+D Support Group from the start of the project on January 1, 2000 to the time of the Technical Review Meeting in Mol: 27-29 June, 2005. The objectives to be accomplished were set out in a Baseline document. These were: to define the lower target flow configuration, within the geometric constraints imposed by the physical boundary conditions (geometrical confinement, lead- bismuth eutectic (LBE) inventory, pump capacities, target heat exchanger (THX) power, etc.); to identify, and evaluate, optimum target window design to minimise thermal loads and pressure drops, and to avoid hot-spots and flow instabilities; to demonstrate reliable cooling of the lower target enclosure (LTE); to demonstrate the structural integrity of the lower section of the Iiquid-metal container LMC) and its internal components, and that of the LTE; to provide best-estimate safety margins on target coolability and structural integrity under operational flow conditions; to investigate, quantify, and make recommendations regarding, abnormal target operation including possible accident scenarios). The time-scale set for MEGAPIE was always such that much of the design work needed to be carried out at the same time as the R+D support. Often, the target design was changing faster than the time required to perform the detailed computer simulations. As a consequence, many of the simulations reported or referenced in this document do not refer to the very latest target design, and in many respects the results and conclusions must be regarded as generic in nature. Nonetheless, very valuable work has been carried out by the various organisations, and better understanding of the expected temperature distributions and stress levels in the operating MEGAPIE target has been gained, and direct feed-back to the design team on various aspects of the design details has taken place as a consequence of this work. As the design

  5. Summary report for MEGAPIE R+D Task Group X4: Fluid dynamics and structure mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Smith, B. L

    2006-03-15

    The document chronicles, and draws summary conclusions from, the activities of the X4 R+D Support Group from the start of the project on January 1, 2000 to the time of the Technical Review Meeting in Mol: 27-29 June, 2005. The objectives to be accomplished were set out in a Baseline document. These were: to define the lower target flow configuration, within the geometric constraints imposed by the physical boundary conditions (geometrical confinement, lead- bismuth eutectic (LBE) inventory, pump capacities, target heat exchanger (THX) power, etc.); to identify, and evaluate, optimum target window design to minimise thermal loads and pressure drops, and to avoid hot-spots and flow instabilities; to demonstrate reliable cooling of the lower target enclosure (LTE); to demonstrate the structural integrity of the lower section of the Iiquid-metal container LMC) and its internal components, and that of the LTE; to provide best-estimate safety margins on target coolability and structural integrity under operational flow conditions; to investigate, quantify, and make recommendations regarding, abnormal target operation including possible accident scenarios). The time-scale set for MEGAPIE was always such that much of the design work needed to be carried out at the same time as the R+D support. Often, the target design was changing faster than the time required to perform the detailed computer simulations. As a consequence, many of the simulations reported or referenced in this document do not refer to the very latest target design, and in many respects the results and conclusions must be regarded as generic in nature. Nonetheless, very valuable work has been carried out by the various organisations, and better understanding of the expected temperature distributions and stress levels in the operating MEGAPIE target has been gained, and direct feed-back to the design team on various aspects of the design details has taken place as a consequence of this work. As the design

  6. Getting under the hood: how and for whom does increasing course structure work?

    Science.gov (United States)

    Eddy, Sarah L; Hogan, Kelly A

    2014-01-01

    At the college level, the effectiveness of active-learning interventions is typically measured at the broadest scales: the achievement or retention of all students in a course. Coarse-grained measures like these cannot inform instructors about an intervention's relative effectiveness for the different student populations in their classrooms or about the proximate factors responsible for the observed changes in student achievement. In this study, we disaggregate student data by racial/ethnic groups and first-generation status to identify whether a particular intervention-increased course structure-works better for particular populations of students. We also explore possible factors that may mediate the observed changes in student achievement. We found that a "moderate-structure" intervention increased course performance for all student populations, but worked disproportionately well for black students-halving the black-white achievement gap-and first-generation students-closing the achievement gap with continuing-generation students. We also found that students consistently reported completing the assigned readings more frequently, spending more time studying for class, and feeling an increased sense of community in the moderate-structure course. These changes imply that increased course structure improves student achievement at least partially through increasing student use of distributed learning and creating a more interdependent classroom community. © 2014 S. L. Eddy and K. A. Hogan. CBE—Life Sciences Education © 2014 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  7. Statistical structure of intrinsic climate variability under global warming

    Science.gov (United States)

    Zhu, Xiuhua; Bye, John; Fraedrich, Klaus

    2017-04-01

    Climate variability is often studied in terms of fluctuations with respect to the mean state, whereas the dependence between the mean and variability is rarely discussed. We propose a new climate metric to measure the relationship between means and standard deviations of annual surface temperature computed over non-overlapping 100-year segments. This metric is analyzed based on equilibrium simulations of the Max Planck Institute-Earth System Model (MPI-ESM): the last millennium climate (800-1799), the future climate projection following the A1B scenario (2100-2199), and the 3100-year unforced control simulation. A linear relationship is globally observed in the control simulation and thus termed intrinsic climate variability, which is most pronounced in the tropical region with negative regression slopes over the Pacific warm pool and positive slopes in the eastern tropical Pacific. It relates to asymmetric changes in temperature extremes and associates fluctuating climate means with increase or decrease in intensity and occurrence of both El Niño and La Niña events. In the future scenario period, the linear regression slopes largely retain their spatial structure with appreciable changes in intensity and geographical locations. Since intrinsic climate variability describes the internal rhythm of the climate system, it may serve as guidance for interpreting climate variability and climate change signals in the past and the future.

  8. Structural changes in elastically stressed crystallites under irradiation

    International Nuclear Information System (INIS)

    Zolnikov, K.P.; Korchuganov, A.V.; Kryzhevich, D.S.; Chernov, V.M.; Psakhie, S.G.

    2015-01-01

    The response of elastically stressed iron and vanadium crystallites to atomic displacement cascades was investigated by molecular dynamics simulation. Interatomic interaction in vanadium was described by a many-body potential calculated in the Finnis–Sinclair approximation of the embedded atom method. Interatomic interaction in iron was described by a many-body potential constructed in the approximation of valence-electron gas. The crystallite temperature in the calculations was varied from 100 to 600 K. The elastically stressed state in the crystallites was formed through uniaxial tension by 4–8% such that their volume remained unchanged. The energy of a primary knock-on atom was varied from 0.5 to 50 keV. It is shown that the lower the temperature and the higher the strain degree of an initial crystallite, the lower the threshold primary knock-on atom energy for plastic deformation generation in the crystallite. The structural rearrangements induced in the crystallites by an atomic displacement cascade are similar to those induced by mechanical loading. It is found that the rearrangements are realized through twinning

  9. Structure of glutaminyl cyclase from Drosophila melanogaster in space group I4

    International Nuclear Information System (INIS)

    Kolenko, Petr; Koch, Birgit; Rahfeld, Jens-Ulrich; Schilling, Stephan; Demuth, Hans-Ulrich; Stubbs, Milton T.

    2013-01-01

    The structure of ligand-free glutaminyl cyclase from D. melanogaster has been determined in a novel crystal form belonging to space group I4. The structure of ligand-free glutaminyl cyclase (QC) from Drosophila melanogaster (DmQC) has been determined in a novel crystal form. The protein crystallized in space group I4, with unit-cell parameters a = b = 122.3, c = 72.7 Å. The crystal diffracted to a resolution of 2 Å at the home source. The structure was solved by molecular replacement and was refined to an R factor of 0.169. DmQC exhibits a typical α/β-hydrolase fold. The electron density of three monosaccharides could be localized. The accessibility of the active site will facilitate structural studies of novel inhibitor-binding modes

  10. How did market competition affect outpatient utilization under the diagnosis-related group-based payment system?

    Science.gov (United States)

    Kim, Seung Ju; Park, Eun-Cheol; Kim, Sun Jung; Han, Kyu-Tae; Jang, Sung-In

    2017-06-01

    Although competition is known to affect quality of care, less is known about the effects of competition on outpatient health service utilization under the diagnosis-related group payment system. This study aimed to evaluate these effects and assess differences before and after hospitalization in South Korea. Population-based retrospective observational study. We used two data set including outpatient data and hospitalization data from National Health Claim data from 2011 to 2014. Participants who were admitted to the hospital for hemorrhoidectomy were included. A total of 804 884 hospitalizations were included in our analysis. The outcome variables included the costs associated with outpatient examinations and the number of outpatient visits within 30 days before and after hospitalization. High-competition areas were associated with lower pre-surgery examination costs (rate ratio [RR]: 0.88, 95% confidence interval [CI]: 0.88-0.89) and fewer outpatient visits before hospitalization (RR: 0.98, 95% CI: 0.98-0.99) as well as after hospitalization compared with moderate-competition areas. Our study reveals that outpatient health service utilization is affected by the degree of market competition. Future evaluations of hospital performance should consider external factors such as market structure and hospital location. © The Author 2017. Published by Oxford University Press in association with the International Society for Quality in Health Care. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

  11. Heuristic optimization of group structure using Physics-Based Fitness Approximation

    International Nuclear Information System (INIS)

    Yi, C.; Sjoden, G.; Edgar, C.

    2016-01-01

    Highlight: • A heuristic method is developed to optimize the broad group structure. • Two Fitness function designs (PBFA and SDFF) are introduced. • A neutron detector model (DRCC) is used to compare PBFA and SDFF. • PBFA shows a good agreement with SDFF with much less computational cost. - Abstract: In Multi-Group (MG) deterministic radiation transport simulation applications, Fine-Group (FG) cross section libraries are often collapsed, or down-sampled into Broad-Group (BG) libraries to reduce computational cost. Previously, we developed a heuristic approach to determine the optimal BG group structure using the Particle Swarm Optimization (PSO) algorithm. A key step in PSO is to evaluate the fitness function, which measures the optimality, or fitness of a given group structure. In this paper, we demonstrated that a Simulation-Driven Fitness Function (SDFF) can be readily formulated by performing transport simulations on a BG structure, and then comparing the results, such as flux distribution, detector response, and/or k-effective, with the reference FG simulation solution. While the PSO approach is very effective in searching for global optimum in a very large solution space, the SDFF evaluation process can be very time-consuming since it requires a large number of BG transport simulations, even though a single BG simulation usually costs much less time than the reference FG calculation. To overcome this problem, a novel Physics-Based Fitness Approximation (PBFA) approach is developed based on the contributon transport theory. Compared to SDFF, PBFA does not require BG transport simulations. Therefore, it significantly reduces the computational cost for evaluation of the fitness function. We performed a thorough numerical test on a neutron detector model, the Dual Range Coincidence Counter, to examine the efficacy of PBFA. We found that a strong positive correlation exists between SDFF and PBFA. Thanks to this new finding, we can replace PBFA with SDFF to

  12. Lifetime Reliability Prediction of Ceramic Structures Under Transient Thermomechanical Loads

    Science.gov (United States)

    Nemeth, Noel N.; Jadaan, Osama J.; Gyekenyesi, John P.

    2005-01-01

    An analytical methodology is developed to predict the probability of survival (reliability) of ceramic components subjected to harsh thermomechanical loads that can vary with time (transient reliability analysis). This capability enables more accurate prediction of ceramic component integrity against fracture in situations such as turbine startup and shutdown, operational vibrations, atmospheric reentry, or other rapid heating or cooling situations (thermal shock). The transient reliability analysis methodology developed herein incorporates the following features: fast-fracture transient analysis (reliability analysis without slow crack growth, SCG); transient analysis with SCG (reliability analysis with time-dependent damage due to SCG); a computationally efficient algorithm to compute the reliability for components subjected to repeated transient loading (block loading); cyclic fatigue modeling using a combined SCG and Walker fatigue law; proof testing for transient loads; and Weibull and fatigue parameters that are allowed to vary with temperature or time. Component-to-component variation in strength (stochastic strength response) is accounted for with the Weibull distribution, and either the principle of independent action or the Batdorf theory is used to predict the effect of multiaxial stresses on reliability. The reliability analysis can be performed either as a function of the component surface (for surface-distributed flaws) or component volume (for volume-distributed flaws). The transient reliability analysis capability has been added to the NASA CARES/ Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code. CARES/Life was also updated to interface with commercially available finite element analysis software, such as ANSYS, when used to model the effects of transient load histories. Examples are provided to demonstrate the features of the methodology as implemented in the CARES/Life program.

  13. Biogeographical boundaries, functional group structure and diversity of Rocky Shore communities along the Argentinean coast.

    Directory of Open Access Journals (Sweden)

    Evie A Wieters

    Full Text Available We investigate the extent to which functional structure and spatial variability of intertidal communities coincide with major biogeographical boundaries, areas where extensive compositional changes in the biota are observed over a limited geographic extension. We then investigate whether spatial variation in the biomass of functional groups, over geographic (10's km and local (10's m scales, could be associated to species diversity within and among these groups. Functional community structure expressed as abundance (density, cover and biomass and composition of major functional groups was quantified through field surveys at 20 rocky intertidal shores spanning six degrees of latitude along the southwest Atlantic coast of Argentina and extending across the boundaries between the Argentinean and Magellanic Provinces. Patterns of abundance of individual functional groups were not uniformly matched with biogeographical regions. Only ephemeral algae showed an abrupt geographical discontinuity coincident with changes in biogeographic boundaries, and this was limited to the mid intertidal zone. We identified 3-4 main 'groups' of sites in terms of the total and relative abundance of the major functional groups, but these did not coincide with biogeographical boundaries, nor did they follow latitudinal arrangement. Thus, processes that determine the functional structure of these intertidal communities are insensitive to biogeographical boundaries. Over both geographical and local spatial scales, and for most functional groups and tidal levels, increases in species richness within the functional group was significantly associated to increased total biomass and reduced spatial variability of the group. These results suggest that species belonging to the same functional group are sufficiently uncorrelated over space (i.e. metres and site-to-site to stabilize patterns of biomass variability and, in this manner, provide a buffer, or "insurance", against

  14. GENDER AND AGE GROUP STRUCTURE IN HARGHITA COUNTY, AT THE 2011 CENSUS

    Directory of Open Access Journals (Sweden)

    George-Bogdan TOFAN

    2016-06-01

    Full Text Available The study at hand aims to present the gender and age structure of the population of Harghita County, recorded at the 2011 Census. For better emphasis, following geographical logic, we shall commence by bringing forward the essential characteristics of gender structure, more exactly both genders (BG, followed by the male population (M and the female population (F, as well as age groups, encompassing the 0-19 group (young people, 20-59 group (adult and the over 60 group (elderly. The data is first presented at the larger territorial level, then the analysis shifts focus towards the evolution of each administrativeterritorial unit’s population, as well as the urban-rural situation.

  15. Nano structures of group 13-15 mixed heptamer clusters: a computational study.

    Science.gov (United States)

    Mohajeri, Afshan; Ebadi, Mahsa

    2012-05-10

    The structural and thermodynamic characteristics of lowest-energy structures of group 13-15 mixed heptamers in two distinct series [(HM)(k)(HM')(l)(NH)(7)] (M, M' = B, Al, Ga and k + l = 7) and [(HGa)(7)(YH)(m)(Y'H)(n)] (Y,Y' = N, P, As and m + n = 7) have been systematically investigated using the density functional approach. Our main goal is to get knowledge of the preferential bonding patterns of the first three rows of group 13-15 elements for the construction of mixed heptameric clusters. Structural parameters, thermodynamic properties of oligomerization reaction, band gaps, and dipole moments of the 18 lowest-energy structures of the studied heptamers in each series are compared to their corresponding binary parents, that is, [(HM)(7)(NH)(7)] and [(HGa)(7)(YH)(7)]. The stability of different isomer structures is discussed to reveal the competitiveness of group 13 and 15 bonding. Mixed heptamers are predicted to be thermodynamically more stable compared to a mixture of monomers. However, the favorability for the generation of mixed heptamers strongly depends on the nature of inserted metal and nonmetal pairs of group 13-15. Moreover, it is found that among all studied heptamers the smaller band gaps correspond to arsenic containing species which are close to the semiconducting regime, around 4.62-4.98 eV.

  16. Line group techniques in description of the structural phase transitions in some superconductors

    Science.gov (United States)

    Meszaros, CS.; Balint, A.; Bankuti, J.

    1995-01-01

    The main features of the theory of line groups, and their irreducible representations are briefly discussed, as well as the most important applications of them. A new approach in the general symmetry analysis of the modulated systems is presented. It is shown, that the line group formalism could be a very effective tool in the examination of the structural phase transitions in High Temperature SUperconductors. As an example, the material YBa2Cu3O(7-x) is discussed briefly.

  17. Mobile phones and social structures: an exploration of a closed user group in rural Ghana.

    Science.gov (United States)

    Kaonga, Nadi Nina; Labrique, Alain; Mechael, Patricia; Akosah, Eric; Ohemeng-Dapaah, Seth; Baah, Joseph Sakyi; Kodie, Richmond; Kanter, Andrew S; Levine, Orin

    2013-09-03

    In the Millennium Villages Project site of Bonsaaso, Ghana, the Health Team is using a mobile phone closed user group to place calls amongst one another at no cost. In order to determine the utilization and acceptability of the closed user group amongst users, social network analysis and qualitative methods were used. Key informants were identified and interviewed. The key informants also kept prospective call journals. Billing statements and de-identified call data from the closed user group were used to generate data for analyzing the social structure revealed by the network traffic. The majority of communication within the closed user group was personal and not for professional purposes. The members of the CUG felt that the group improved their efficiency at work. The methods used present an interesting way to investigate the social structure surrounding communication via mobile phones. In addition, the benefits identified from the exploration of this closed user group make a case for supporting mobile phone closed user groups amongst professional groups.

  18. Structural and predictive equivalency of the Wisconsin Smoking Withdrawal Scale across three racial/ethnic groups.

    Science.gov (United States)

    Castro, Yessenia; Kendzor, Darla E; Businelle, Michael S; Mazas, Carlos A; Cofta-Woerpel, Ludmila; Cinciripini, Paul M; Wetter, David W

    2011-07-01

    The Wisconsin Smoking Withdrawal Scale (WSWS) is a valid and reliable scale among non-Latino Whites but has not been validated for use among other racial/ethnic groups despite increasing use with these populations. The current study examined the structural invariance and predictive equivalency of the WSWS across three racial/ethnic groups. The WSWS scores of 424 African American, Latino, and White smokers receiving smoking cessation treatment were analyzed in a series of factor analyses and multiple-group analyses. Additionally, hierarchical logistic regression analyses were conducted to determine whether WSWS scores differentially predicted smoking relapse across racial/ethnic groups. These analyses were consistent with a step-down hierarchical regression procedure for examination of test bias. The 7-factor structure of the WSWS was largely confirmed in the current study, with the exception of the removal of two offending items. Evidence of full invariance across race/ethnicity was found in multiple-group analyses. The WSWS total score and subscales measuring anger, anxiety, concentration, and sadness predicted relapse, whereas the hunger, craving, and sleep subscales did not. None of these scales displayed differential predictive ability across race/ethnicity. The WSWS sleep subscale showed a significant interaction with race/ethnicity such that it was a significant predictor of relapse among Whites but not African Americans or Latinos. Overall, the WSWS is similar in structure and predictive of relapse across racial/ethnic groups. Caution should be exercised when using the WSWS sleep subscale with African Americans and Latinos.

  19. An optimized ultra-fine energy group structure for neutron transport calculations

    International Nuclear Information System (INIS)

    Huria, Harish; Ouisloumen, Mohamed

    2008-01-01

    This paper describes an optimized energy group structure that was developed for neutron transport calculations in lattices using the Westinghouse lattice physics code PARAGON. The currently used 70-energy group structure results in significant discrepancies when the predictions are compared with those from the continuous energy Monte Carlo methods. The main source of the differences is the approximations employed in the resonance self-shielding methodology. This, in turn, leads to ambiguous adjustments in the resonance range cross-sections. The main goal of developing this group structure was to bypass the self-shielding methodology altogether thereby reducing the neutronic calculation errors. The proposed optimized energy mesh has 6064 points with 5877 points spanning the resonance range. The group boundaries in the resonance range were selected so that the micro group cross-sections matched reasonably well with those derived from reaction tallies of MCNP for a number of resonance absorbers of interest in reactor lattices. At the same time, however, the fast and thermal energy range boundaries were also adjusted to match the MCNP reaction rates in the relevant ranges. The resulting multi-group library was used to obtain eigenvalues for a wide variety of reactor lattice numerical benchmarks and also the Doppler reactivity defect benchmarks to establish its adequacy. (authors)

  20. Multiple Comparison of Age Groups in Bone Mineral Density under Heteroscedasticity

    Directory of Open Access Journals (Sweden)

    Ahmet Sezer

    2015-01-01

    Full Text Available Osteoporosis is a silent disease because individuals may not know that they have osteoporosis until their bones become so fragile. Bone mineral density (BMD test helps to detect osteoporosis and determine the risk fractures. This study covers bone measurement data from total body dual energy X-ray absorptiometry scans for 28,454 persons who participated in the 1996–2006 National Health and Nutrition Examination Survey in USA Dual energy X-ray absorptiometry (DXA method is known as the primary method for detecting osteoporosis because of its high precision and accuracy. Testing the equality of the means of normal populations when the variances are unknown and unequal is a fundamental problem in clinical trials and biomedical research. In this study we compare age groups based upon BMD in case of unequal variance being present among the groups. First we test equality of variances among the age groups by the Hartley test. And then Scott-Smith test is used to test equality of BMD means for the age groups. Finally, Tukey-Cramer confidence intervals are constructed to detect which groups start to differ from the reference group in which BMD reaches the peak level.

  1. Photoreflectance studies of electronic transitions in quantum well structures under high presure

    Science.gov (United States)

    Chandrasekhar, Holakere R.; Chandrasekhar, Meera

    1990-08-01

    Superlattices of alternating layers of semiconductors were first proposed1 in 1970, and since then a variety of structures have been grown. Their technological importance has spurred considerable experimental and theoretical work. The unique feature of quantum confinement of carriers has made possible unusual devices. By combining various semiconductors and alloys of ffl-V, 11-TV and group IV materials, unusual band lineups between neighboring layers have been obtained. Both lattice matched and strained layer structures have been grown. In this article we will focus on the electronic structure of the quantum well heterostructures under the external perturbation of hydrostatic pressure. Pressure has been used extensively to investigate materials in regions of phase space not otherwise accessib1. lu the study of quantum well structures, it has also been used to move band edges in a controlled fashion, and alter band lineups, allowing the determination of band offsets with an accuracy that was not possible without the use of pressure. As in bulk semiconductors, optical techniques provide powerful tools in studying the electronic states in quantum well heterostructures (QWH). Photoluminescence (PL) spectroscopy is only sensitive to spectral features associated with energy states close to the bottom of the well due to rapid thermalization of carriers. Photoluminescence excitation (PLE) is often limited by the availability of tunable lasers. Photoreflectance (PR), on the other hand, can provide a rich structure due to both symmetry allowed and forbidden transitions encompassing the entire quantum well. This sensitivity is due to the derivative nature of the spectroscopy. Experiments can be carried out easily at different temperatures and over wide spectral regions. This article is organized as follows. In section 2 we will review some of the theoretical calculations of electronic bands in quantum wells and discuss the changes expected under pressure. In Sec. 3, we

  2. Structural evolution of defective graphene under heat treatment and gamma irradiation

    Science.gov (United States)

    Zhang, Yifei; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Liu, Liangsen; Zhao, Lihuan; Li, Jing; Jing, Miaolei

    2018-03-01

    We have studied the structural change of defective graphene built by annealing in different temperature under the condition of gamma irradiation. Firstly, we found the heat treatment not only reduced but also striped the graphene. This behavior made defects become more firstly and then become less with the increase of temperature. And then gamma irradiation removed some oxygen-containing groups, by a simultaneous changed over carbon in the graphitic lattice from sp3 to sp2. Also, the gamma irradiation decreased the interlayer spacing between graphene lowest to 3.391 Å and made a crosslink which resulting in the size of the ordered gaining. A variation was detected by Raman spectroscopy that the amorphous carbon was declined after gamma irradiation. Furtherly we found the degree of this decline raised first and then diminished with the increase in the number of defects. The change in repair capacity of gamma irradiation presented a strategy for repairing the defects of graphene.

  3. Eigenvalue perturbation theory of structured matrices under generic structured rank one perturbations: Symplectic, orthogonal, and unitary matrices.

    NARCIS (Netherlands)

    Ran, A.C.M.; Mehl, Chr.; Mehrmann, V.; Rodman, L.

    2014-01-01

    We study the perturbation theory of structured matrices under structured rank one perturbations, with emphasis on matrices that are unitary, orthogonal, or symplectic with respect to an indefinite inner product. The rank one perturbations are not necessarily of arbitrary small size (in the sense of

  4. How Are Distributed Groups Affected by an Imposed Structuring of their Decision-Making Process?

    DEFF Research Database (Denmark)

    Lundell, Anders Lorentz; Hertzum, Morten

    2011-01-01

    Groups often suffer from ineffective communication and decision making. This experimental study compares distributed groups solving a preference task with support from either a communication system or a system providing both communication and a structuring of the decision-making process. Results...... show that groups using the latter system spend more time solving the task, spend more of their time on solution analysis, spend less of their time on disorganized activity, and arrive at task solutions with less extreme preferences. Thus, the type of system affects the decision-making process as well...

  5. Structure of Symmetry Groups via Cartan's Method: Survey of Four Approaches

    Directory of Open Access Journals (Sweden)

    Oleg I. Morozov

    2005-10-01

    Full Text Available In this review article we discuss four recent methods for computing Maurer-Cartan structure equations of symmetry groups of differential equations. Examples include solution of the contact equivalence problem for linear hyperbolic equations and finding a contact transformation between the generalized Hunter-Saxton equation and the Euler-Poisson equation.

  6. Movements and group structure of giraffe (Giraffa camelopardalis) in Lake Manyara National Park, Tanzania.

    NARCIS (Netherlands)

    Jeugd, van der H.P.; Prins, H.H.T.

    2000-01-01

    Movements and group structure of giraffe Giraffa camelopardalis were studied in Lake Manyara National Park, northern Tanzania. The giraffe population in Manyara had increased from 60 to 85 individuals between the early 1980s and 1991. This increase may have been the result of an increase in browse

  7. Movements and group structure of giraffe (Giraffa camelopardalis) in Lake Manyara National Park, Tanzania

    NARCIS (Netherlands)

    van der Jeugd, HP; Prins, HHT

    Movements and group structure of giraffe Giraffa camelopardalis were studied in Lake Manyara National Park, northern Tanzania. The giraffe population in Manyara had increased from 60 to 85 individuals between the early 1980s and 1991. This increase may have been the result of an increase in browse

  8. The influence of age-group structure on genetic gain and ...

    African Journals Online (AJOL)

    Demographic data were collected on one privately owned stud herd each of the Bonsmara, Brahman and Drakensberger beef breeds, farmed extensively in different natural environments in the Republic of South Africa, to study the influence of herd age-group structure on the rate of genetic gain and production. The number ...

  9. fast minimization on the xiao map using row group structure rules

    African Journals Online (AJOL)

    user

    Nigerian Journal of Technology, Vol. 13, No. 1 September 1989, Osuagwu, Anyanwu and Agada 51. FAST MINIMIZATION ON THE XIAO MAP USING ROW GROUP. STRUCTURE RULES. C.C. Osuagwu, C.D. Anyanwu and J.O. Agada. Department of Electronic Engineering. University of Nigeria, Nsukka. ABSTRACT.

  10. The influence of age-group structure on genetic gain and ...

    African Journals Online (AJOL)

    that the age structure has a significant influence on genetic gain in Merino flocks. This is due to the inverse relationship be- tween the intensity of selection and the generation interval which becomes apparent when the number of male and female age-groups is changed. An important conclusion from their results was that ...

  11. Heuristic algorithms for feature selection under Bayesian models with block-diagonal covariance structure.

    Science.gov (United States)

    Foroughi Pour, Ali; Dalton, Lori A

    2018-03-21

    Many bioinformatics studies aim to identify markers, or features, that can be used to discriminate between distinct groups. In problems where strong individual markers are not available, or where interactions between gene products are of primary interest, it may be necessary to consider combinations of features as a marker family. To this end, recent work proposes a hierarchical Bayesian framework for feature selection that places a prior on the set of features we wish to select and on the label-conditioned feature distribution. While an analytical posterior under Gaussian models with block covariance structures is available, the optimal feature selection algorithm for this model remains intractable since it requires evaluating the posterior over the space of all possible covariance block structures and feature-block assignments. To address this computational barrier, in prior work we proposed a simple suboptimal algorithm, 2MNC-Robust, with robust performance across the space of block structures. Here, we present three new heuristic feature selection algorithms. The proposed algorithms outperform 2MNC-Robust and many other popular feature selection algorithms on synthetic data. In addition, enrichment analysis on real breast cancer, colon cancer, and Leukemia data indicates they also output many of the genes and pathways linked to the cancers under study. Bayesian feature selection is a promising framework for small-sample high-dimensional data, in particular biomarker discovery applications. When applied to cancer data these algorithms outputted many genes already shown to be involved in cancer as well as potentially new biomarkers. Furthermore, one of the proposed algorithms, SPM, outputs blocks of heavily correlated genes, particularly useful for studying gene interactions and gene networks.

  12. Synthesis, structural characterization and myorelaxant activity of 4-naphthylhexahydroquinoline derivatives containing different ester groups

    Directory of Open Access Journals (Sweden)

    Gündüz Miyase Gözde

    2016-01-01

    Full Text Available The present study reports the synthesis, structural characterization and myorelaxant activity evaluation of a series of 16 novel 4-naphthyl-hexahydroquinoline derivatives. The compounds were achieved by one-pot microwave-assisted method via a modified Hantzsch reaction. The structures of the compounds were confirmed by various spectral methods like IR, 1D-2D NMR techniques and mass analysis. X-ray studies of compound 10 provided further evidence for the proposed structure. To evaluate their myorelaxant activities, the Emax and pD2 values of the compounds and nifedipine were determined on isolated rabbit gastric fundus smooth muscle strips. The obtained results indicated that introduction of long chain alkyl groups such as 2-methoxyethyl or 2-(methacryloyloxyethyl moiety to the ester group led to the most active compounds.

  13. Emergence of leadership in a robotic fish group under diverging individual personality traits

    NARCIS (Netherlands)

    Wang, Chen; Chen, Xiaojie; Xie, Guangming; Cao, Ming

    2017-01-01

    Variations of individual’s personality traits have been identified before as one of the possible mechanisms for the emergence of leadership in an interactive collective, which may lead to benefits for the group as a whole. Complementing the large number of existing literatures on using simulation

  14. The Effect of Sensitivity Group Participation Under Different Conditions on the Reduction of Racial Prejudice.

    Science.gov (United States)

    Hindman, Audrey; Forsyth, Douglas R.

    This report outlines the procedures used for experimentally testing the effectiveness of a sensitivity group model in reducing racial prejudice among both black and white college students. The proposal is designed to explore the assumption that increasingly effective racial relations follow from increased understanding, acceptance, and tolerance…

  15. An unreliable group arrival queue with k stages of service, retrial under variant vacation policy

    Science.gov (United States)

    Radha, J.; Indhira, K.; Chandrasekaran, V. M.

    2017-11-01

    In this research work we considered repairable retrial queue with group arrival and the server utilize the variant vacations. A server gives service in k stages. Any arriving group of units finds the server free, one from the group entering the first stage of service and the rest are joining into the orbit. After completion of the i th stage of service, the customer may have the option to choose (i+1)th stage of service with probability θi , with probability pi may join into orbit as feedback customer or may leave the system with probability {q}i=≤ft\\{\\begin{array}{l}1-{p}i-{θ }i,i=1,2,\\cdots k-1\\ 1-{p}i,i=k\\end{array}\\right\\}. If the orbit is empty at the service completion of each stage service, the server takes modified vacation until at least one customer appears in the orbit on the server returns from a vacation. Busy server may get to breakdown and the service channel will fail for a short interval of time. By using the supplementary variable method, steady state probability generating function for system size, some system performance measures are discussed.

  16. Wettability, soil organic matter and structure-properties of typical chernozems under the forest and under the arable land

    Science.gov (United States)

    Bykova, Galina; Umarova, Aminat; Tyugai, Zemfira; Milanovskiy, Evgeny; Shein, Evgeny

    2017-04-01

    Intensive tillage affects the properties of soil: decrease in content of soil organic matter and in hydrophobicity of the soil's solid phase, the reduction of amount of water stable aggregates - all this leads to deterioration of the structure of the soil and affects the process of movement of moisture in the soil profile. One of the hypotheses of soil's structure formation ascribes the formation of water stable aggregates with the presence of hydrophobic organic substances on the surface of the soil's solid phase. The aim of this work is to study the effect of tillage on properties of typical chernozems (pachic Voronic Chernozems, Haplic Chernozems) (Russia, Kursk region), located under the forest and under the arable land. The determination of soil-water contact angle was performed by a Drop Shape Analyzer DSA100 (Krüss GmbH, Germany) by the static sessile drop method. For all samples the content of total and organic carbon by dry combustion in oxygen flow and the particle size distribution by the laser diffraction method on the device Analysette 22 comfort, FRITCH, Germany were determined. The estimation of aggregate composition was performed by dry sieving (AS 200, Retsch, Germany), the content of water stable aggregates was estimated by the Savvinov method. There was a positive correlation between the content of organic matter and soil's wettability in studied soils, a growth of contact angle with the increasing the content of organic matter. Under the forest the content of soil organic matter was changed from 6,41% on the surface up to 1,9% at the depth of 100 cm. In the Chernozem under the arable land the organic carbon content in arable horizon is almost two times less. The maximum of hydrophobicity (78.1o) was observed at the depth of 5 cm under the forest. In the profile under the arable land the contact angle value at the same depth was 50o. The results of the structure analysis has shown a decrease in the content of agronomically valuable and water

  17. The Hopf algebra structure of the character rings of classical groups

    International Nuclear Information System (INIS)

    Fauser, Bertfried; Jarvis, Peter D; King, Ronald C

    2013-01-01

    The character ring Char-GL of covariant irreducible tensor representations of the general linear group admits a Hopf algebra structure isomorphic to the Hopf algebra Symm-Λ of symmetric functions. Here we study the character rings Char-O and Char-Sp of the orthogonal and symplectic subgroups of the general linear group within the same framework of symmetric functions. We show that Char-O and Char-Sp also admit natural Hopf algebra structures that are isomorphic to that of Char-GL, and hence to Symm-Λ. The isomorphisms are determined explicitly, along with the specification of standard bases for Char-O and Char-Sp analogous to those used for Symm-Λ. A major structural change arising from the adoption of these bases is the introduction of new orthogonal and symplectic Schur–Hall scalar products. Significantly, the adjoint with respect to multiplication no longer coincides, as it does in the Char-GL case, with a Foulkes derivative or skew operation. The adjoint and Foulkes derivative now require separate definitions, and their properties are explored here in the orthogonal and symplectic cases. Moreover, the Hopf algebras Char-O and Char-Sp are not self-dual. The dual Hopf algebras Char-O * and Char-Sp are identified. Finally, the Hopf algebra of the universal rational character ring Char-GLrat of mixed irreducible tensor representations of the general linear group is introduced and its structure maps identified. (paper)

  18. Compact groups in theory and practice - IV. The connection to large-scale structure

    Science.gov (United States)

    Mendel, J. Trevor; Ellison, Sara L.; Simard, Luc; Patton, David R.; McConnachie, Alan W.

    2011-12-01

    We investigate the properties of photometrically selected compact groups (CGs) in the Sloan Digital Sky Survey. In this paper, the fourth in a series, we focus on understanding the characteristics of our observed CG sample with particular attention paid to quantifying and removing contamination from projected foreground or background galaxies. Based on a simple comparison of pairwise redshift likelihoods, we find that approximately half of CGs in the parent sample contain one or more projected (interloping) members; our final clean sample contains 4566 galaxies in 1086 CGs. We show that half of the remaining CGs are associated with rich groups (or clusters), i.e. they are embedded sub-structure. The other half have spatial distributions and number-density profiles consistent with the interpretation that they are either independently distributed structures within the field (i.e. they are isolated) or associated with relatively poor structures. Comparisons of late-type and red-sequence fractions in radial annuli show that galaxies around apparently isolated CGs resemble the field population by 300 to 500 kpc from the group centre. In contrast, the galaxy population surrounding embedded CGs appears to remain distinct from the field out beyond 1 to 2 Mpc, consistent with results for rich groups. We take this as additional evidence that the observed distinction between CGs, i.e. isolated versus embedded, is a separation between different host environments.

  19. Attitudes underlying corneal donation in a group of trainee allied health professionals.

    Directory of Open Access Journals (Sweden)

    Donal McGlade

    Full Text Available BACKGROUND: The focus of this study was to investigate factors that may influence personal willingness to register consent to donate corneal tissue upon death using the theory of planned behaviour in a relatively ethnically homogenous group of trainee allied health professionals. The attainment of this knowledge will be of paramount importance in relation to potential interventions that are designed to change donation-related behaviour. METHODS: A questionnaire-based study was undertaken with 92 pre-registration nurses (mean age 24.0 years (standard deviation ± 5.6 years; female:male = 89:3 enrolled at a University in Northern Ireland. Intention to register consent to donate corneal tissue upon death was assessed using both direct and belief-based measures found in the theory of planned behaviour. Descriptive statistics were used to assess demographic information, with correlation and regression analyses being used to identify factors influencing intentions. RESULTS: The majority of participants were religious (94.6%, n = 87 and mostly Protestant (58.7%, n = 54 or Catholic (35.9%, n = 33. Generally speaking, the theory of planned behaviour accounted for 84% of the variance in intention to register consent. In relation to the constructs found in the theory of planned behaviour, attitude was found to be the strongest predictor of intention to register consent, with subjective norm being the second strongest predictor. Perceived behavioural control did not significantly predict intention to register consent. CONCLUSIONS: The theory of planned behaviour has allowed an understanding of the factors that influence the personal intentions of a group of future allied health professionals from the same ethnic group to register consent to donate their corneal tissue.

  20. Chemoselective Deprotection of Sulfonamides Under Acidic Conditions: Scope, Sulfonyl Group Migration, and Synthetic Applications.

    Science.gov (United States)

    Javorskis, Tomas; Orentas, Edvinas

    2017-12-15

    Chemoselective acidic hydrolysis of sulfonamides with trifluoromethanesulfonic acid has been evaluated as a deprotection method and further extended to more complex synthetic applications. In contrast to conventional troublesome sulfonamide hydrolysis, a near-stoichiometric amount of acid was found to be sufficient to bring about efficient deprotection of various neutral or electron-deficient N-arylsulfonamides, whereas electron-rich substrates provided sulfonyl group migration products. The deprotection method developed is fully selective for N-arylsulfonamides, and the possibility to discriminate among various different sulfonamides is demonstrated.

  1. Renormalization-Group Transformations Under Strong Mixing Conditions: Gibbsianness and Convergence of Renormalized Interactions

    Science.gov (United States)

    Bertini, Lorenzo; Cirillo, Emilio N. M.; Olivieri, Enzo

    1999-12-01

    In this paper we study a renormalization-group map: the block averaging transformation applied to Gibbs measures relative to a class of finite-range lattice gases, when suitable strong mixing conditions are satisfied. Using a block decimation procedure, cluster expansion, and detailed comparison between statistical ensembles, we are able to prove Gibbsianness and convergence to a trivial (i.e., Gaussian and product) fixed point. Our results apply to the 2D standard Ising model at any temperature above the critical one and arbitrary magnetic field.

  2. Synthesis, structural characterization, and thermal stability studies of heteroleptic cadmium(II) dithiocarbamate with different pyridyl groups

    Science.gov (United States)

    Onwudiwe, Damian C.; Hosten, Eric C.

    2018-01-01

    The synthesis, characterization and crystal structures of three chloroform solvated adducts of cadmium with mixed ligands of N-alkyl-N-phenyldithiocarbamate and pyridine, 2,2-bipyridine and 1, 10 phenanthroline represented as [CdL1L2 (py)2]·CHCl3(1), [CdL1L2bpy]•CHCl3(2), and [CdL1L2phen]•CHCl3(3) (LI = N-methyl-N-phenyldithiocarbamate, L2 = N-ethyl-N-phenyldithiocarbamate, py = pyridine, bpy = 2,2-bipyridine and phen = 1,10-phenanthroline) respectively are reported. Complex 1, which crystallized in the monoclinic space group P-1, is a centrosymmetric dimeric structure where each Cd center is bonded to two monodentate pyridine, a bidentate terminal dithiocarbamate, and another bidentate bridging dithiocarbamate to form a four-membered ring. Complex 2 crystallized in the monoclinic space group P21/c, with four discrete monomeric molecules in the asymmetric unit. The structure presents a cadmium atom coordinated by two sulphur atoms of a dithiocarbamate ligand and two nitrogen atoms of the 2,2‧-bipyridine to form a CdS4N2 fragment, thus giving the structure around the Cd atom a distorted trigonal prism geometry. Complex 3 contains two discrete monomeric molecules of (phenanthroline) (N, N-methyl phenyl-N, N-ethyl phenyl dithiocarbamato)cadmium (II) per unit cell, and the complex crystallized in the triclinic space group P-1. The structure showed that the Cd atom is bonded to two bidentate dithiocarbamate ligands and to one bidentate phenanthroline ligand in a distorted trigonal prism geometry. All the compounds resulted in CdS as residue upon thermal decomposition process conducted under inert atmosphere.

  3. Effectiveness of Cognitive-Behavioral Group Therapy on Craving, Depression & Anxiety among the Opiate Abusers Under MMT

    Directory of Open Access Journals (Sweden)

    Fereshte Momeni

    2010-04-01

    Full Text Available Objectives: This study aimed at evaluating the effectiveness of cognitive-behavioral group therapy on craving, symptoms of depression and anxiety among the patients under MMT. Methods: In this experimental study, 36 opiate addicts under MMT were selected out of all the patients referring to Iranian National Center of Addiction Studies on a judgmental sampling method and were randomly allocated to two experimental and control groups. In experimental group, a total sum of 8 sessions (one session per week of cognitive behavioral group therapy were delivered. The main theme of these sessions were efficient management of craving, negative mood and anxiety. Data were gathered with different questionnaires including the questionnaire of demographic data, RPS for craving assessment, BDI-II for depression and BAI for anxiety. Different methods of statistical analysis were implemented. Results: The results indicated that post test and follow-up scores of craving index were decreased significantly (P<0.05. Depression and Anxiety scores showed significant decrease as well. Discussion: Considering the above mentioned findings, we concluded that cognitive-behavioral group therapy was effective in significantly decreasing craving and symptoms of anxiety and depression in opiate addicts under MMT.

  4. Yo-Yo Intermittent Recovery Test Performance in Subelite Gaelic Football Players From Under Thirteen to Senior Age Groups.

    Science.gov (United States)

    Roe, Mark; Malone, Shane

    2016-11-01

    Roe, M and Malone, S. Yo-Yo intermittent recovery test performance in subelite Gaelic football players from under thirteen to senior age groups. J Strength Cond Res 30 (11): 3187-3193, 2016-Gaelic football is indigenous to Ireland and has similar locomotion profiles to soccer and Australian Football. Given the increasing attention on long-term player development, investigations on age-related variation in Yo-Yo intermittent recovery test level 1 (Yo-YoIR1) performance may provide useful information in talent identification, program design, and player monitoring. Therefore, the aim of this study was to evaluate Yo-YoIR1 performance across Gaelic football age groups. Male participants (n = 355) were recruited from division one, Gaelic football teams. Participants were allocated to one of the 7 groups according to respective age groups from under 13 (U13), under 14, under 15 (U15), under 16 (U16), minor, under 21 (U21), to senior age groups. Total Yo-YoIR1 distance (m) increased progressively from U13 (885 ± 347 m) to U16 (1,595 ± 380 m) equating to a rate of change of 180.2%. In comparison to U13, total distance at minor (1,206 ± 327 m) increased by 136.4%. Subsequent increases were observed in U21 (1,585 ± 445 m) and senior players (2,365 ± 489). Minimum (800-880 m) and maximum (2,240-2,280 m) total distances were comparable for U15, U16, and U21 players. Differences in total distance (m) for all age groups were statistically significant when compared to U13 players (p age groups for total distance was deemed to be large (effect size > 0.8). Similar trends were observed for maximum velocity and estimated V[Combining Dot Above]O2max. The evolution of Yo-YoIR1 performance in Gaelic football players from adolescents to adulthood highlights how maturation may influence sport-related running ability. Changes in Yo-YoIR1 performance should be closely monitored to optimize interventions for individuals transitioning across age groups.

  5. Report of the task group on the seismic behaviour of structures: status report

    International Nuclear Information System (INIS)

    1997-04-01

    In 1995, the CSNI Committee on the Safety of Nuclear Installations) approved a new mandate for PWG-3 and the new title 'Integrity of Components and Structures'. The PWG-3 is assisted by three task groups, one of which is addressing the problem of seismic behavior of structures. Ten topics were identified: engineering characterization of seismic input, site response, soil structure interaction, identification of functions and classification of systems, structures and components, structural response and capacity evaluation (including effects of aging and degradation), component and equipment response and capacity evaluation (including effects of aging and degradation), response and capacity evaluation of distribution systems (piping, cable trays, conduit, HVAC), load combination and acceptance criteria, uncertainties (PSA and margins), plant seismic instrumentation and trip. This report summarizes the seismic issues and activities in various member countries (Canada, Czech Republic, France, Hungary, Italy, Japan, Spain, Switzerland, United Kingdom, United States) and international organizations (IAEA), provides a summary of the important issues that are of collective interest to the group members, and recommends a future programme of work to address these issues

  6. Effectiveness of Cognitive-Behavioral Group Therapy on Improving Quality of Life in Opiate Addicts under Methadone Maintenance Treatment

    Directory of Open Access Journals (Sweden)

    Fereshteh Momeni

    2013-04-01

    Full Text Available Objective: This study was aimed to assess the effectiveness of cognitive- behavioral group therapy on improvement of quality of life in opiate patients under methadone maintenance treatment. Method: This was a semi experimental study using control group also pre-test, post-test and follow-up. Thirty six patients on MMT were selected between the entire opiate addicts referred to Iranian national center for addiction studies within judgmental sampling and were randomly assigned into experimental and control groups. They were all administered the WHOQOL-BREF. In experimental group, cognitive behavior group therapy was performed in 8 sessions and the control group was registered in the waiting list for the CBGT. Findings: Data analysis revealed that the mean WHOQOL-BREF score in the experimental group had significant higher increase when compared with that of the control group. But it wasn’t significant in follow up. Conclusion: Results demonstrated the effectiveness of cognitive–behavior group therapy On improvement of quality of life of opiate addicts on MMT in short term but didn’t seem to be effective in long term.

  7. Demographic Histories, Isolation and Social Factors as Determinants of the Genetic Structure of Alpine Linguistic Groups

    Science.gov (United States)

    Coia, Valentina; Capocasa, Marco; Anagnostou, Paolo; Pascali, Vincenzo; Scarnicci, Francesca; Boschi, Ilaria; Battaggia, Cinzia; Crivellaro, Federica; Ferri, Gianmarco; Alù, Milena; Brisighelli, Francesca; Busby, George B. J.; Capelli, Cristian; Maixner, Frank; Cipollini, Giovanna; Viazzo, Pier Paolo; Zink, Albert; Destro Bisol, Giovanni

    2013-01-01

    Great European mountain ranges have acted as barriers to gene flow for resident populations since prehistory and have offered a place for the settlement of small, and sometimes culturally diverse, communities. Therefore, the human groups that have settled in these areas are worth exploring as an important potential source of diversity in the genetic structure of European populations. In this study, we present new high resolution data concerning Y chromosomal variation in three distinct Alpine ethno-linguistic groups, Italian, Ladin and German. Combining unpublished and literature data on Y chromosome and mitochondrial variation, we were able to detect different genetic patterns. In fact, within and among population diversity values observed vary across linguistic groups, with German and Italian speakers at the two extremes, and seem to reflect their different demographic histories. Using simulations we inferred that the joint effect of continued genetic isolation and reduced founding group size may explain the apportionment of genetic diversity observed in all groups. Extending the analysis to other continental populations, we observed that the genetic differentiation of Ladins and German speakers from Europeans is comparable or even greater to that observed for well known outliers like Sardinian and Basques. Finally, we found that in south Tyroleans, the social practice of Geschlossener Hof, a hereditary norm which might have favored male dispersal, coincides with a significant intra-group diversity for mtDNA but not for Y chromosome, a genetic pattern which is opposite to those expected among patrilocal populations. Together with previous evidence regarding the possible effects of “local ethnicity” on the genetic structure of German speakers that have settled in the eastern Italian Alps, this finding suggests that taking socio-cultural factors into account together with geographical variables and linguistic diversity may help unveil some yet to be understood

  8. Demographic histories, isolation and social factors as determinants of the genetic structure of Alpine linguistic groups.

    Directory of Open Access Journals (Sweden)

    Valentina Coia

    Full Text Available Great European mountain ranges have acted as barriers to gene flow for resident populations since prehistory and have offered a place for the settlement of small, and sometimes culturally diverse, communities. Therefore, the human groups that have settled in these areas are worth exploring as an important potential source of diversity in the genetic structure of European populations. In this study, we present new high resolution data concerning Y chromosomal variation in three distinct Alpine ethno-linguistic groups, Italian, Ladin and German. Combining unpublished and literature data on Y chromosome and mitochondrial variation, we were able to detect different genetic patterns. In fact, within and among population diversity values observed vary across linguistic groups, with German and Italian speakers at the two extremes, and seem to reflect their different demographic histories. Using simulations we inferred that the joint effect of continued genetic isolation and reduced founding group size may explain the apportionment of genetic diversity observed in all groups. Extending the analysis to other continental populations, we observed that the genetic differentiation of Ladins and German speakers from Europeans is comparable or even greater to that observed for well known outliers like Sardinian and Basques. Finally, we found that in south Tyroleans, the social practice of Geschlossener Hof, a hereditary norm which might have favored male dispersal, coincides with a significant intra-group diversity for mtDNA but not for Y chromosome, a genetic pattern which is opposite to those expected among patrilocal populations. Together with previous evidence regarding the possible effects of "local ethnicity" on the genetic structure of German speakers that have settled in the eastern Italian Alps, this finding suggests that taking socio-cultural factors into account together with geographical variables and linguistic diversity may help unveil some yet

  9. Special quasirandom structures for binary/ternary group IV random alloys

    KAUST Repository

    Chroneos, Alexander I.

    2010-06-01

    Simulation of defect interactions in binary/ternary group IV semiconductor alloys at the density functional theory level is difficult due to the random distribution of the constituent atoms. The special quasirandom structures approach is a computationally efficient way to describe the random nature. We systematically study the efficacy of the methodology and generate a number of special quasirandom cells for future use. In order to demonstrate the applicability of the technique, the electronic structures of E centers in Si1-xGex and Si1-x -yGexSny alloys are discussed for a range of nearest neighbor environments. © 2010 Elsevier B.V. All rights reserved.

  10. Test-retest reliability of the underlying latent factor structure of alcohol subjective response.

    Science.gov (United States)

    Lutz, Joseph A; Childs, Emma

    2017-04-01

    Alcohol subjective experiences are multi-dimensional and demonstrate wide inter-individual variability. Recent efforts have sought to establish a clearer understanding of subjective alcohol responses by identifying core constructs derived from multiple measurement instruments. The aim of this study was to evaluate the temporal stability of this approach to conceptualizing alcohol subjective experiences across successive alcohol administrations in the same individuals. Healthy moderate alcohol drinkers (n = 104) completed six experimental sessions each, three with alcohol (0.8 g/kg), and three with a non-alcoholic control beverage. Participants reported subjective mood and drug effects using standardized questionnaires before and at repeated times after beverage consumption. We explored the underlying latent structure of subjective responses for all alcohol administrations using exploratory factor analysis and then tested measurement invariance over the three successive administrations using multi-group confirmatory factor analyses. Exploratory factor analyses on responses to alcohol across all administrations yielded four factors representing "Positive mood," "Sedation," "Stimulation/Euphoria," and "Drug effects and Urges." A confirmatory factor analysis on the separate administrations indicated acceptable configural and metric invariance and moderate scalar invariance. In this study, we demonstrate temporal stability of the underlying constructs of subjective alcohol responses derived from factor analysis. These findings strengthen the utility of this approach to conceptualizing subjective alcohol responses especially for use in prospective and longitudinal alcohol challenge studies relating subjective response to alcohol use disorder risk.

  11. Neutron scattering study of structure and dynamics of ammonium halides under high pressure

    International Nuclear Information System (INIS)

    Kozlenko, D.P.; Balagurov, A.M.; Savenko, B.N.; Glazkov, V.P.; Somenkov, V.A.; Hull, S.

    1999-01-01

    Complete text of publication follows. Structural changes in ammonium halides ND 4 Cl, ND 4 Br and ND 4 F at pressures up to 40 kbar and ND 4 I at pressures up to 86 kbar have been studied bz means of neutron diffraction at room temperature. The pressure dependencies of the lattice parameter a and the deuterium position parameter u were obtained. It was found that the order - disorder II-IV phase transition in ND 4 Br and ND 4 Cl occurs at equal critical values of u, u cr =0.152(2). For ND 4 F, u is initially higher than u cr and only the ordered CsCl type phase III exists at high pressure. For ND 4 I, no II-IV phase transition was observed. A phase transition into the recently discovered high pressure phase V was detected in ND 4 I at 80 4 I(V) was found to be the same as the structure of the low temperature phase ND 4 I(III) - tetragonal one with antiparallel ordering of ammonium ions, space group P4/nmm. Vibrational spectra of NH 4 I and HN 4 F have been studied by means of incoherent inelastic neutron scattering at pressure up to 40 kbar. Vibration and transverse optical (TO) modes frequencies as functions of pressure were obtained. Both frequencies increase under pressure. (author)

  12. Braided matrix structure of the Sklyanin algebra and of the quantum Lorentz group

    International Nuclear Information System (INIS)

    Majid, S.

    1993-01-01

    Braided groups and braided matrices are novel algebraic structures living in braided or quasitensor categories. As such they are a generalization of super-groups and super-matrices to the case of braid statistics. Here we construct braided group versions of the standard quantum groups U q (g). They have the same FRT generators l ± but a matrix braided-coproduct ΔL=LxL, where L=l + Sl - , and are self-dual. As an application, the degenerate Sklyanin algebra is shown to be isomorphic to the braided matrices BM 1 (2); it is a braided-commutative bialgebra in a braided category. As a second application, we show that the quantum double D(U q (sl 2 )) (also known as the 'quantum Lorentz group') is the semidirect product as an algebra of two copies of U q (sl 2 ), and also a semidirect product as a coalgebra if we use braid statistics. We find various results of this type for the doubles of general quantum groups and their semi-limits as doubles of the Lie algebras of Poisson Lie groups. (orig.)

  13. Dielectric investigations under irradiation of photo chromic copolymers with azobenzene moieties in the side group

    International Nuclear Information System (INIS)

    Turky, G.; Stumpe, J.; Schonhals, A.

    2005-01-01

    Photo chromic polymers are promising materials for optical switching and image storage because the orientation of mesogens in thin films of these materials can be modified by light. Real time dielectric spectroscopy is applied to study the time dependence of the light induced trans/cis-isomerization process for polymethacrylate copolymer system. For the investigated azobenzene group it was found that the dipole moment of the Z state is greater than that of E state. Therefore normalized . increases with increasing irradiation time (E/Z isomerization) at different considered wavelengths. A steady state is reached after about 10000 s. The effect of irradiation reduces at longer and shorter wavelengths. Stretched exponential equation was used to describe the effect of irradiation time on the normalized permittivity

  14. Platinum group metal particles aggregation in nuclear glass melts under the effect of temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hanotin, Caroline [CEA Marcoule, DEN/MAR/DTCD/SECM/LDMC, Bagnols-sur-Cèze, F-30207 (France); Puig, Jean [Laboratoire PROMES-CNRS, UPR 8521, Font-Romeu Odeillo, F-66120 (France); Neyret, Muriel, E-mail: muriel.neyret@cea.fr [CEA Marcoule, DEN/MAR/DTCD/SECM/LDMC, Bagnols-sur-Cèze, F-30207 (France); Marchal, Philippe [Laboratoire Réactions et Génie des Procédés (LRGP-GEMICO), Université de Lorraine-CNRS, UMR 7274, Nancy F-54001 (France)

    2016-08-15

    The viscosity of simulated high level radioactive waste glasses containing platinum group metal particles is studied over a wide range of shear stress, as a function of the particles content and the temperature, thanks to a stress imposed rheometer, coupled to a high-temperature furnace. The system shows a very shear thinning behavior. At high shear rate, the system behaves as a suspension of small clusters and individual particles and is entirely controlled by the viscosity of the glass matrix as classical suspensions. At low shear rate, above a certain fraction in platinum group metal particles, the apparition of macroscopic aggregates made up of chains of RuO{sub 2} particles separated by thin layers of glass matrix strongly influences the viscosity of the nuclear glass and leads, in particular, to the apparition of yield stress and thixotropic effects. The maximum size of these clusters as well as their effective volume fraction have been estimated by a balance between Van der Waals attractive forces and hydrodynamic forces due to shear flow. We showed experimentally and theoretically that this aggregation phenomenon is favored by an increase of the temperature, owing to the viscosity decrease of the glass matrix, leading to an unusual increase of the suspension viscosity. - Highlights: • The macroscopic aggregates made up of RuO{sub 2} particles strongly influence the nuclear glass viscosity. • The maximum size of clusters as well as their effective volume fraction can be estimated. • This aggregation phenomenon is favored by an increase of the temperature. • A viscosity model as a function of the PGM content, volume fraction and shear stress is proposed.

  15. Finding Risk Groups by Optimizing Artificial Neural Networks on the Area under the Survival Curve Using Genetic Algorithms.

    Directory of Open Access Journals (Sweden)

    Jonas Kalderstam

    Full Text Available We investigate a new method to place patients into risk groups in censored survival data. Properties such as median survival time, and end survival rate, are implicitly improved by optimizing the area under the survival curve. Artificial neural networks (ANN are trained to either maximize or minimize this area using a genetic algorithm, and combined into an ensemble to predict one of low, intermediate, or high risk groups. Estimated patient risk can influence treatment choices, and is important for study stratification. A common approach is to sort the patients according to a prognostic index and then group them along the quartile limits. The Cox proportional hazards model (Cox is one example of this approach. Another method of doing risk grouping is recursive partitioning (Rpart, which constructs a decision tree where each branch point maximizes the statistical separation between the groups. ANN, Cox, and Rpart are compared on five publicly available data sets with varying properties. Cross-validation, as well as separate test sets, are used to validate the models. Results on the test sets show comparable performance, except for the smallest data set where Rpart's predicted risk groups turn out to be inverted, an example of crossing survival curves. Cross-validation shows that all three models exhibit crossing of some survival curves on this small data set but that the ANN model manages the best separation of groups in terms of median survival time before such crossings. The conclusion is that optimizing the area under the survival curve is a viable approach to identify risk groups. Training ANNs to optimize this area combines two key strengths from both prognostic indices and Rpart. First, a desired minimum group size can be specified, as for a prognostic index. Second, the ability to utilize non-linear effects among the covariates, which Rpart is also able to do.

  16. Novel stable structure of Li3PS4 predicted by evolutionary algorithm under high-pressure

    Directory of Open Access Journals (Sweden)

    S. Iikubo

    2018-01-01

    Full Text Available By combining theoretical predictions and in-situ X-ray diffraction under high pressure, we found a novel stable crystal structure of Li3PS4 under high pressures. At ambient pressure, Li3PS4 shows successive structural transitions from γ-type to β-type and from β-type to α type with increasing temperature, as is well established. In this study, an evolutionary algorithm successfully predicted the γ-type crystal structure at ambient pressure and further predicted a possible stable δ-type crystal structures under high pressure. The stability of the obtained structures is examined in terms of both static and dynamic stability by first-principles calculations. In situ X-ray diffraction using a synchrotron radiation revealed that the high-pressure phase is the predicted δ-Li3PS4 phase.

  17. On the structure and the antisymmetric ν3 IR mode of covalent azide group

    Science.gov (United States)

    Rozenberg, Mark; Tibika-Apfelbaum, Francoise

    2013-03-01

    A new correlation ν3 = 1997 + 1.17 × 103 Δr between the stretching mode ν3 of the IR band frequency and the bond length asymmetry expressed as Δr ≡ r(Nα - Nβ) - r(Nβ - Nγ) is established in molecular azides Rsbnd Nαsbnd Nβsbnd Nγ with the correlation coefficient R = 0.972. The database represents recent spectral and structural information for more than fifty organic molecules and inorganic metal complexes. Because the absolute term practically coincides with the ν3 frequency value for the free azide group, this correlation shows that the blue shift Δν3 (in cm-1) of the ν3 from the free azide value varies in direct proportion with the N3 group asymmetry Δr (in Å) (Δν3 = 1.17 × 103 Δr) at formation of different azide structures.

  18. Review of parameters influencing the structural response of a submerged body under cavitation conditions

    OpenAIRE

    Escaler, X; De La Torre, O; Farhat, M

    2015-01-01

    Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to thei r surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at t...

  19. Structural strength of cancellous specimens from bovine femur under cyclic compression

    Directory of Open Access Journals (Sweden)

    Kaori Endo

    2016-01-01

    Full Text Available The incidence of osteoporotic fractures was estimated as nine million worldwide in 2000, with particular occurrence at the proximity of joints rich in cancellous bone. Although most of these fractures spontaneously heal, some fractures progressively collapse during the early post-fracture period. Prediction of bone fragility during progressive collapse following initial fracture is clinically important. However, the mechanism of collapse, especially the gradual loss of the height in the cancellous bone region, is not clearly proved. The strength of cancellous bone after yield stress is difficult to predict since structural and mechanical strength cannot be determined a priori. The purpose of this study was to identify whether the baseline structure and volume of cancellous bone contributed to the change in cancellous bone strength under cyclic loading. A total of fifteen cubic cancellous bone specimens were obtained from two 2-year-old bovines and divided into three groups by collection regions: femoral head, neck, and proximal metaphysis. Structural indices of each 5-mm cubic specimen were determined using micro-computed tomography. Specimens were then subjected to five cycles of uniaxial compressive loading at 0.05 mm/min with initial 20 N loading, 0.3 mm displacement, and then unloading to 0.2 mm with 0.1 mm displacement for five successive cycles. Elastic modulus and yield stress of cancellous bone decreased exponentially during five loading cycles. The decrease ratio of yield stress from baseline to fifth cycle was strongly correlated with bone volume fraction (BV/TV, r = 0.96, p < 0.01 and structural model index (SMI, r = − 0.81, p < 0.01. The decrease ratio of elastic modulus from baseline to fifth cycle was also correlated with BV/TV (r = 0.80, p < 0.01 and SMI (r = − 0.78, p < 0.01. These data indicate that structural deterioration of cancellous bone is associated with bone strength after yield stress. This study suggests that

  20. Method of investigating the structures of observed groups of objects of the Galaxy and Metagalaxy

    International Nuclear Information System (INIS)

    Kudryavtsev, S.M.

    1985-01-01

    The random quantities-geometrical characteristics of a group of objects are proposed for estimating the reality and investigating the visible structure features of galactic and metagalactic fields. The method was applied for solving the problem of reality of the stellar Orion and Aquila rings. One comes to the conclusion: the Orion ring is real and the Aquila ring can be a consequense of illusion

  1. Using machine learning to identify structural breaks in single-group interrupted time series designs.

    Science.gov (United States)

    Linden, Ariel; Yarnold, Paul R

    2016-12-01

    Single-group interrupted time series analysis (ITSA) is a popular evaluation methodology in which a single unit of observation is being studied, the outcome variable is serially ordered as a time series and the intervention is expected to 'interrupt' the level and/or trend of the time series, subsequent to its introduction. Given that the internal validity of the design rests on the premise that the interruption in the time series is associated with the introduction of the treatment, treatment effects may seem less plausible if a parallel trend already exists in the time series prior to the actual intervention. Thus, sensitivity analyses should focus on detecting structural breaks in the time series before the intervention. In this paper, we introduce a machine-learning algorithm called optimal discriminant analysis (ODA) as an approach to determine if structural breaks can be identified in years prior to the initiation of the intervention, using data from California's 1988 voter-initiated Proposition 99 to reduce smoking rates. The ODA analysis indicates that numerous structural breaks occurred prior to the actual initiation of Proposition 99 in 1989, including perfect structural breaks in 1983 and 1985, thereby casting doubt on the validity of treatment effects estimated for the actual intervention when using a single-group ITSA design. Given the widespread use of ITSA for evaluating observational data and the increasing use of machine-learning techniques in traditional research, we recommend that structural break sensitivity analysis is routinely incorporated in all research using the single-group ITSA design. © 2016 John Wiley & Sons, Ltd.

  2. Risk transfer formula for individual and small group markets under the Affordable Care Act.

    Science.gov (United States)

    Pope, Gregory C; Bachofer, Henry; Pearlman, Andrew; Kautter, John; Hunter, Elizabeth; Miller, Daniel; Keenan, Patricia

    2014-01-01

    The Affordable Care Act provides for a program of risk adjustment in the individual and small group health insurance markets in 2014 as Marketplaces are implemented and new market reforms take effect. The purpose of risk adjustment is to lessen or eliminate the influence of risk selection on the premiums that plans charge. The risk adjustment methodology includes the risk adjustment model and the risk transfer formula. This article is the third of three in this issue of the Medicare & Medicaid Research Review that describe the ACA risk adjustment methodology and focuses on the risk transfer formula. In our first companion article, we discussed the key issues and choices in developing the methodology. In our second companion paper, we described the risk adjustment model that is used to calculate risk scores. In this article we present the risk transfer formula. We first describe how the plan risk score is combined with factors for the plan allowable premium rating, actuarial value, induced demand, geographic cost, and the statewide average premium in a formula that calculates transfers among plans. We then show how each plan factor is determined, as well as how the factors relate to each other in the risk transfer formula. The goal of risk transfers is to offset the effects of risk selection on plan costs while preserving premium differences due to factors such as actuarial value differences. Illustrative numerical simulations show the risk transfer formula operating as anticipated in hypothetical scenarios.

  3. Psychosocial Problems Among Truant Youth: A Multi-Group, Exploratory Structural Equation Modeling Analysis.

    Science.gov (United States)

    Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven

    2012-01-01

    Truant youth represent a critical group needing problem-oriented research and involvement in effective services. The limited number of studies on the psychosocial functioning of truant youths have focused on one or a few problem areas, rather than examining co-morbid problem behaviors. The present study addresses the need to examine the interrelationships of multiple domains of psychosocial functioning, including substance involvement, mental health, and delinquency, among truant youth. Exploratory structural equation modeling on baseline data collected on 219 truant youths identified two major factors reflecting psychosocial functioning, and found the factor structure was similar across major sociodemographic subgroups. Further analyses supported the validity of the factor structure. The research and service delivery implications of the findings are discussed.

  4. Use of three-dimensional parameters in the analysis of crystal structures under compression

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci

    2007-01-01

    . For a complete understanding of structural changes, the behaviour of all coordination polyhedra plus the voids that separate them must be investigated. The structural voids in a framework are identified by a Voronoi tessellation. It can be performed e.g. on the anionic framework alone to find the centres...... of the coordination polyhedra of cations and the voids that separate them. Analysis of individual compressional characteristics of structural components gives clues for the strong and weak parts of structures under high pressures and paths for structural transformations. The expected behaviour of distortion...

  5. Electronic Structures of MgB{$_2$} under Uniaxial and Hydrostatic Compression

    OpenAIRE

    Kobayashi, K.; Yamamoto, K.

    2001-01-01

    Electronic and lattice properties of MgB{$_2$} under uniaxial and hydrostatic compression are calculated. Lattice properties are optimized automatically by using the first-principles molecular dynamics (FPMD) method. Features of the electronic band structures under uniaxial and hydrostatic compression are quite different each other.

  6. Structural Evolution of Human Recombinant alfaB-Crystallin under UV Irradiation

    DEFF Research Database (Denmark)

    Sugiyama, Masaaki; Fujii, Noriko; Morimoto, Yukio

    2008-01-01

    External stresses cause certain proteins to lose their regular structure and aggregate. In order to clarify this abnormal aggregation process, a structural evolution of human recombinant aB-crystallin under UV irradiation was observed with in situ small-angle neutron scattering. The abnormal...

  7. Structure of the herb stratum under different light regimes in the Submontane Atlantic Rain Forest.

    Science.gov (United States)

    Lima, R A F; Gandolfi, S

    2009-05-01

    This study aimed to characterize the structure of the herb stratum in relation to light availability in the Submontane Atlantic Rain Forest at the Carlos Botelho State Park, SP, Brazil. Fortyone 10 x10 m plots were established under the closed canopy (18 plots), small and medium canopy gaps (11) and large canopy gaps dominated by Guadua tagoara (Ness) Kunth (12). Inside each plot, the line intercept method was applied to assess soil coverage as an estimate of density of herb stratum vegetation. Hemispherical photographs were taken at the centre of the plots to evaluate the annual light regime. Overall, Calathea communis Wanderley and S. Vieira had the greater mean coverage, followed by woody seedlings, ground ferns and other herbs (mainly, Araceae, Acanthaceae, Amaranthaceae and Cyperaceae). There were strong correlations among several groups of the herb stratum, such as the negative correlations between woody seedlings with the coverage of C. communis and with rocks. The analysis of the hemispherical photographs confirmed the difference among environments that led to significant differences in the soil coverage of the herb stratum vegetation but woody seedlings. For instance, C. communis showed great coverage in large gaps while ferns were more abundant in small and medium gaps and in the understorey. Other herbs, in turn, demonstrated bigger soil coverage in small and medium gaps. Although this study represents a rough assessment of the structure and composition of the herb stratum, the results found here illustrated the evident relation between herb species density and the environmental variation promoted by changes on canopy structure and topography.

  8. ZZ MATXS70-JEFF87, 69+1 Group MATXS Library in WIMS BOXER Structure

    International Nuclear Information System (INIS)

    Vontobel, P.; Pelloni, S.

    1990-01-01

    Description of program or function: Format: WIMS-BOXER; Number of groups: 69 + 1 groups neutron library; Nuclides: H, He, Li, Be, B, C, N, O, F, Na, Al, Si, Cr, Mn, Fe, Ni, Cu, Kr, Zr, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, I, Xe, Cs, La, Nd, Pm, Sm, Eu, Gd, Lu, Hf, Ta, Au, Pb, Pa, Th, U, Np, Pu, Am, Cm. Origin: JEF-1, EFF-1; Weighting spectrum: yes. The 70 group WIMS-BOXER structure MATXS library contains data for 80 isotopes of 40 chemical elements. Several temperatures, background cross sections and P1 scattering anisotropy are included. The data can be used by most transport and diffusion codes after pre-processing with the MATXS interface codes TRAMIX or TRANSX-CTR

  9. Structural and vibrational dynamics of molecular solids under variable temperature and pressure

    Science.gov (United States)

    Schatschneider, Bohdan Hindulak

    An ultra-high resolution FTIR study (0.01cm-1) coupled with molecular simulations of para-terphenyl (PTP) under variable temperatures and pressures has been conducted in an effort to better understand the molecular dynamics (MD) of organic molecular crystals. PTP's use as an electrooptic material and as a host matrix for single molecular spectroscopy has created significant interest into the systems dynamics under variable conditions. Our high resolution study reveals many structure and dynamics changes in the PTP matrix as a result of changes in temperature and pressure. Further spectroscopic analysis using MD verifies these structural and dynamics alterations. Accurately modeled pressure and temperature phase transitions between the low-temperature low-pressure triclinic phase and the high-pressure high-temperature monoclinic phase of PTP was accomplished by a one-parameter optimization of the torsion potential component of the polymer consistent force field (PCFF) along with incorporation of COMPASS' (Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies) non-bond parameters. Initial MD simulations implementing the universal force field COMPASS could not adequately model the experimental crystal structure at 113K, nor could it reproduce the known transition temperature at ambient pressure or yield a well-defined transition pressure at low temperature. Therefore, we needed to create a new potential which was shown to reproduce the solid-solid phase transitions. The previously never simulated pressure induced solid-solid phase transition of PTP at low temperature (20K) and varying pressures (0-1GPa) was modeled. The symmetry based crystal/molecular rearrangement shows a compression and distortion of the unit cell and corresponding angles along with a flattening of the once twisted PTP molecules at high pressures (>0.5GPa). A fourth crystal phase (Phase IV) has been successfully identified through analysis of the individual molecule

  10. Crystal structure of bassetite and saleeite. New insight into autunite-group minerals

    Energy Technology Data Exchange (ETDEWEB)

    Dal Bo, Fabrice; Hatert, Frederic [Liege Univ. (Belgium). Lab. de Mineralogie; Mees, Florias [Royal Museum for Central Africa, Tervuren (Belgium); Philippo, Simon [Musee National d' Histoire Naturelle, Luxembourg (Luxembourg). Section Mineralogie; Baijot, Maxime; Fontaine, Francois [Liege Univ. (Belgium). Dept. de Geologie

    2016-06-15

    The crystal structures of two autunite-group minerals have been solved recently. The crystal structure of bassetite, Fe{sup 2+}[(UO{sub 2})(PO{sub 4})]{sub 2}(H{sub 2}O){sub 10}, from the type locality in Cornwall, United Kingdom (Basset Mines) was solved for the first time. Bassetite is monoclinic, space group P2{sub 1}/n, a = 6.961(1), b = 20.039(2), c = 6.974(1) Aa and β = 90.46(1) . The crystal structure of saleeite, Mg[(UO{sub 2})(PO{sub 4})]{sub 2}(H{sub 2}O){sub 10}, from Shinkolobwe, Democratic Republic of Congo, was also solved. Saleeite is monoclinic, space group P2{sub 1}/n, a = 6.951(1), b = 19.942(1), c = 6.967(1) Aa and β = 90.58(1) . The crystal structure investigation of bassetite (R{sub 1} = 0.0658 for 1879 observed reflections with vertical stroke F{sub o} vertical stroke ≥ 4σ{sub F}) and saleeite (R{sub 1} = 0.0307 for 1990 observed reflections with vertical stroke F{sub o} vertical stroke ≥ 4σ{sub F}) confirms that both minerals are topologically identical and that bassetite contains ten water molecules per formula unit. Their structure contains autunite-type sheets, [(UO{sub 2})(PO{sub 4})]{sup -}, consisting of corner-sharing UO{sub 6} square bipyramids and PO{sub 4} tetrahedra. Iron and magnesium are surrounded by water molecules to form Fe(H{sub 2}O){sub 6} or Mg(H{sub 2}O){sub 6} octahedra located in interlayer, between the autunite-type sheets. Two isolated independent water molecules are also located in interlayer. Energy-dispersive X-ray spectroscopy analysis confirmed the chemical composition obtained from structure refinement. These new data prompt a re-assessment of minerals of the autunite and meta-autunite groups.

  11. On the structure and applications of the Bondi-Metzner-Sachs group

    Science.gov (United States)

    Alessio, Francesco; Esposito, Giampiero

    This work is a pedagogical review dedicated to a modern description of the Bondi-Metzner-Sachs (BMS) group. Minkowski space-time has an interesting and useful group of isometries, but, for a generic space-time, the isometry group is simply the identity and hence provides no significant informations. Yet symmetry groups have important role to play in physics; in particular, the Poincaré group describing the isometries of Minkowski space-time plays a role in the standard definitions of energy-momentum and angular-momentum. For this reason alone it would seem to be important to look for a generalization of the concept of isometry group that can apply in a useful way to suitable curved space-times. The curved space-times that will be taken into account are the ones that suitably approach, at infinity, Minkowski space-time. In particular we will focus on asymptotically flat space-times. In this work, the concept of asymptotic symmetry group of those space-times will be studied. In the first two sections we derive the asymptotic group following the classical approach which was basically developed by Bondi, van den Burg, Metzner and Sachs. This is essentially the group of transformations between coordinate systems of a certain type in asymptotically flat space-times. In the third section the conformal method and the notion of “asymptotic simplicity” are introduced, following mainly the works of Penrose. This section prepares us for another derivation of the BMS group which will involve the conformal structure, and is thus more geometrical and fundamental. In the subsequent sections we discuss the properties of the BMS group, e.g. its algebra and the possibility to obtain as its subgroup the Poincaré group, as we may expect. The paper ends with a review of the BMS invariance properties of classical gravitational scattering discovered by Strominger, that are finding application to black hole physics and quantum gravity in the literature.

  12. Do common eiders nest in kin groups? Microgeographic genetic structure in a philopatric sea duck

    Science.gov (United States)

    Sonsthagen, S.A.; Talbot, S.L.; Lanctot, Richard B.; McCracken, K.G.

    2010-01-01

    We investigated local genetic associations among female Pacific common eiders (Somateria mollissima v-nigrum) nesting in a stochastic Arctic environment within two groups of barrier islands (Simpson Lagoon and Mikkelsen Bay) in the Beaufort Sea, Alaska. Nonrandom genetic associations were observed among nesting females using regional spatial autocorrelation analyses for distance classes up to 1000 m in Simpson Lagoon. Nearest-neighbour analyses identified clusters of genetically related females with positive lr values observed for 0-13% and 0-7% of the comparisons in Simpson Lagoon and Mikkelsen Bay, respectively, across years. These results indicate that a proportion of females are nesting in close proximity to more genetically related individuals, albeit at low frequency. Such kin groupings may form through active association between relatives or through natal philopatry and breeding site fidelity. Eiders nest in close association with driftwood, which is redistributed annually by seasonal storms. Yet, genetic associations were still observed. Microgeographic structure may thus be more attributable to kin association than natal philopatry and site fidelity. However, habitat availability may also influence the level of structure observed. Regional structure was present only within Simpson Lagoon and this island group includes at least three islands with sufficient driftwood for colonies, whereas only one island at Mikkelsen Bay has these features. A long-term demographic study is needed to understand more fully the mechanisms that lead to fine-scale genetic structure observed in common eiders breeding in the Beaufort Sea. ?? Published 2010. This article is a US Government work and is in the public domain in the USA.

  13. Molecular structure and modeling studies of azobenzene derivatives containing maleimide groups.

    Science.gov (United States)

    Cojocaru, Corneliu; Airinei, Anton; Fifere, Nicusor

    2013-01-01

    The molecular orbital calculations have been carried out to investigate the structure and stability of (E) / (Z) isomers of some azobenzene derivatives containing maleimide groups. A special attention has been devoted to the compound (E)-1, (E)-1-(4-(phenyldiazenyl)phenyl)-1H-pyrrole-2,5-dione, for which the available crystallographic experimental data have been used to validate the modeling structures computed at the theoretical levels AM1, PM3, RHF/6-31+G(d,p) and B3LYP/6-31+G(d,p). To this end, the discrepancy between experimental and calculated structural parameters has been ascertained in terms of root-mean-square deviation (RMSD). The quantum calculations at the level RHF/6-31+G(d,p) yield the most accurate results on (E)-1 structure giving a deviation error from crystallographic data of about 5.00% for bond lengths and 0.97% for interatomic angles. The theoretical electronic absorption spectra of azobenzene derivatives of concern have been computed by means of configuration-interaction method (CI) at the level of semi-empirical Hamiltonians (AM1 and PM3). Likewise, the molecular energy spectra, electrostatic potential and some quantitative structure activity relationship (QSAR) properties of studied molecules have been computed and discussed in the paper.

  14. Hybrid Group IV Nanophotonic Structures Incorporating Diamond Silicon-Vacancy Color Centers.

    Science.gov (United States)

    Zhang, Jingyuan Linda; Ishiwata, Hitoshi; Babinec, Thomas M; Radulaski, Marina; Müller, Kai; Lagoudakis, Konstantinos G; Dory, Constantin; Dahl, Jeremy; Edgington, Robert; Soulière, Veronique; Ferro, Gabriel; Fokin, Andrey A; Schreiner, Peter R; Shen, Zhi-Xun; Melosh, Nicholas A; Vučković, Jelena

    2016-01-13

    We demonstrate a new approach for engineering group IV semiconductor-based quantum photonic structures containing negatively charged silicon-vacancy (SiV(-)) color centers in diamond as quantum emitters. Hybrid diamond-SiC structures are realized by combining the growth of nano- and microdiamonds on silicon carbide (3C or 4H polytype) substrates, with the subsequent use of these diamond crystals as a hard mask for pattern transfer. SiV(-) color centers are incorporated in diamond during its synthesis from molecular diamond seeds (diamondoids), with no need for ion-implantation or annealing. We show that the same growth technique can be used to grow a diamond layer controllably doped with SiV(-) on top of a high purity bulk diamond, in which we subsequently fabricate nanopillar arrays containing high quality SiV(-) centers. Scanning confocal photoluminescence measurements reveal optically active SiV(-) lines both at room temperature and low temperature (5 K) from all fabricated structures, and, in particular, very narrow line widths and small inhomogeneous broadening of SiV(-) lines from all-diamond nanopillar arrays, which is a critical requirement for quantum computation. At low temperatures (5 K) we observe in these structures the signature typical of SiV(-) centers in bulk diamond, consistent with a double lambda. These results indicate that high quality color centers can be incorporated into nanophotonic structures synthetically with properties equivalent to those in bulk diamond, thereby opening opportunities for applications in classical and quantum information processing.

  15. Diversity, mobility, and structural and functional evolution of group II introns carrying an unusual 3' extension

    Directory of Open Access Journals (Sweden)

    Tourasse Nicolas J

    2011-12-01

    Full Text Available Abstract Background Group II introns are widespread genetic elements endowed with a dual functionality. They are catalytic RNAs (ribozymes that are able of self-splicing and they are also mobile retroelements that can invade genomic DNA. The group II intron RNA secondary structure is typically made up of six domains. However, a number of unusual group II introns carrying a unique extension of 53-56 nucleotides at the 3' end have been identified previously in bacteria of the Bacillus cereus group. Methods In the present study, we conducted combined sequence comparisons and phylogenetic analyses of introns, host gene, plasmid and chromosome of host strains in order to gain insights into mobility, dispersal, and evolution of the unusual introns and their extension. We also performed in vitro mutational and kinetic experiments to investigate possible functional features related to the extension. Results We report the identification of novel copies of group II introns carrying a 3' extension including the first two copies in bacteria not belonging to the B. cereus group, Bacillus pseudofirmus OF4 and Bacillus sp. 2_A_57_CT2, an uncharacterized species phylogenetically close to B. firmus. Interestingly, the B. pseudofirmus intron has a longer extension of 70 bases. From sequence comparisons and phylogenetic analyses, several possible separate events of mobility involving the atypical introns could be identified, including both retrohoming and retrotransposition events. In addition, identical extensions were found in introns that otherwise exhibit little sequence conservation in the rest of their structures, with the exception of the conserved and catalytically critical domains V and VI, suggesting either separate acquisition of the extra segment by different group II introns or a strong selection pressure acting on the extension. Furthermore, we show by in vitro splicing experiments that the 3' extension affects the splicing properties differently in

  16. Novel RNA structural features of an alternatively splicing group II intron from Clostridium tetani.

    Science.gov (United States)

    McNeil, Bonnie A; Zimmerly, Steven

    2014-06-01

    Group II introns are ribozymes in bacterial and organellar genomes that function as self-splicing introns and as retroelements. Previously, we reported that the group II intron C.te.I1 of Clostridium tetani alternatively splices in vivo to produce five distinct coding mRNAs. Accurate fusion of upstream and downstream reading frames requires a shifted 5' splice site located 8 nt upstream of the usual 5' GUGYG motif. This site is specified by the ribozyme through an altered intron/exon-binding site 1 (IBS1-EBS1) pairing. Here we use mutagenesis and self-splicing assays to investigate in more detail the significance of the structural features of the C.te.I1 ribozyme. The shifted 5' splice site is shown to be affected by structures in addition to IBS1-EBS1, and unlike other group II introns, C.te.I1 appears to require a spacer between IBS1 and the GUGYG motif. In addition, the mechanism of 3' exon recognition is modified from the ancestral IIB mechanism to a IIA-like mechanism that appears to be longer than the typical single base-pair interaction and may extend up to 4 bp. The novel ribozyme properties that have evolved for C.te.I1 illustrate the plasticity of group II introns in adapting new structural and catalytic properties that can be utilized to affect gene expression. © 2014 McNeil and Zimmerly; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  17. Comprehensive Wavelengths, Energy Levels, and Hyperfine Structure Parameters of Singly-Ionized Iron-Group Elements

    Science.gov (United States)

    Nave, Gillian

    We propose to measure wavelengths, energy levels, and hyperfine structure parameters of Ni II, Mn II, Sc II and other singly-ionized iron-group elements, covering the wavelength range 80 nm to 5500 nm. We shall use archival data from spectrometers at NIST and Kitt Peak National Observatory for spectra above 140 nm. Additional experimental observations will be taken if needed using Fourier transform spectrometers at NIST. Spectra will be taken using our normal incidence grating spectrograph to provide better sensitivity than the FT spectra and to extend the wavelength range down to 80 nm. We aim to produce a comprehensive description of the spectra of all singly-ionized iron- group elements. The wavelength uncertainty of the strong lines will be better than 1 part in 10^7. For most singly-ionized iron-group elements available laboratory data have uncertainties an order of magnitude larger than astronomical observations over wide spectra ranges. Some of these laboratory measurements date back to the 1960's. Since then, Fourier transform spectroscopy has made significant progress in improving the accuracy and quantity of data in the UV-vis-IR region, but high quality Fourier transform spectra are still needed for Mn II, Ni II and Sc II. Fourier transform spectroscopy has low sensitivity in the VUV region and is limited to wavelengths above 140 nm. Spectra measured with high-resolution grating spectrographs are needed in this region in order to obtain laboratory data of comparable quality to the STIS and COS spectrographs on the Hubble Space Telescope. Currently, such data exist only for Fe II and Cr II. Lines of Sc II, V II, and Mn II show hyperfine structure, but hyperfine structure parameters have been measured for relatively few lines of these elements. Significant errors can occur if hyperfine structure is neglected when abundances are determined from stellar spectra. Measurements of hyperfine structure parameters will be made using Fourier transform spectroscopy

  18. Structural capacity assessment of a generic pre-stressed concrete containment structure under aircraft impact

    International Nuclear Information System (INIS)

    Iliev, Alexander

    2013-01-01

    The studied containment expressed adequate capacity to resist impact loads in the upper range of the studied diapason. The aircraft impact capacity of the containment for impact in the upper part of the cylindrical shell is about 25‐30% higher than the capacity for impact in the middle part of the cylindrical shell. The obtained fragility curves reefed to MoA can be then used for various additional calculations in the safety assessment of nuclear facilities under aircraft impact

  19. Text string detection from natural scenes by structure-based partition and grouping.

    Science.gov (United States)

    Yi, Chucai; Tian, YingLi

    2011-09-01

    Text information in natural scene images serves as important clues for many image-based applications such as scene understanding, content-based image retrieval, assistive navigation, and automatic geocoding. However, locating text from a complex background with multiple colors is a challenging task. In this paper, we explore a new framework to detect text strings with arbitrary orientations in complex natural scene images. Our proposed framework of text string detection consists of two steps: 1) image partition to find text character candidates based on local gradient features and color uniformity of character components and 2) character candidate grouping to detect text strings based on joint structural features of text characters in each text string such as character size differences, distances between neighboring characters, and character alignment. By assuming that a text string has at least three characters, we propose two algorithms of text string detection: 1) adjacent character grouping method and 2) text line grouping method. The adjacent character grouping method calculates the sibling groups of each character candidate as string segments and then merges the intersecting sibling groups into text string. The text line grouping method performs Hough transform to fit text line among the centroids of text candidates. Each fitted text line describes the orientation of a potential text string. The detected text string is presented by a rectangle region covering all characters whose centroids are cascaded in its text line. To improve efficiency and accuracy, our algorithms are carried out in multi-scales. The proposed methods outperform the state-of-the-art results on the public Robust Reading Dataset, which contains text only in horizontal orientation. Furthermore, the effectiveness of our methods to detect text strings with arbitrary orientations is evaluated on the Oriented Scene Text Dataset collected by ourselves containing text strings in nonhorizontal

  20. Influence of the membrane structure plan shape on the displacements under point load

    Directory of Open Access Journals (Sweden)

    Milošević Vuk S.

    2016-01-01

    Full Text Available Deformations of membrane structures under external loads are much more prominent compared to other structures and structural materials. External area loads cause large displacements and redistribution of internal tension forces. Point loads have a less significant impact on changes of internal forces, but a more significant role in creation of local deformations. Previous researches have shown the influence of position and intensity of point loads on the deformations of membrane structures. The aim of this research is to investigate the influence of plan shape of the membrane structure on the displacements under point load. The influence of rhombic shaped plans with different diagonal lengths and ratios is explored. The research is conducted on numerical models in the specialized software Sofistik. Models are loaded with point loads in the point where diagonals intersect and the results are compared.

  1. The Crystal Structure and Behavior of Fenamic Acid-Acridine Complex Under High Pressure.

    Science.gov (United States)

    Jerzykiewicz, Lucjan; Sroka, Adam; Majerz, Irena

    2016-12-01

    The crystal structure of fenamic acid-acridine complex is determined by X-ray diffraction. The strong OHN hydrogen bond linking the complex components and other interactions responsible for packing of the molecules into a crystal are investigated within the Quantum Theory of Atom in Molecule theory. The crystal structure is compared with the structure optimized at B3LYP/6-311++G** level and with the theoretical structures optimized under systematically changed pressure. Analysis of the lattice constants, hydrogen bond lengths, and angles of the inter- and intramolecular hydrogen bond under compression is performed. The structural transformation observed at 5 GPa is connected with a change in the intermolecular OHN hydrogen bond. The proton shifts to acceptor and a new interaction in the crystal appears. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  2. Similarity between community structures of different online social networks and its impact on underlying community detection

    Science.gov (United States)

    Fan, W.; Yeung, K. H.

    2015-03-01

    As social networking services are popular, many people may register in more than one online social network. In this paper we study a set of users who have accounts of three online social networks: namely Foursquare, Facebook and Twitter. Community structure of this set of users may be reflected in these three online social networks. Therefore, high correlation between these reflections and the underlying community structure may be observed. In this work, community structures are detected in all three online social networks. Also, we investigate the similarity level of community structures across different networks. It is found that they show strong correlation with each other. The similarity between different networks may be helpful to find a community structure close to the underlying one. To verify this, we propose a method to increase the weights of some connections in networks. With this method, new networks are generated to assist community detection. By doing this, value of modularity can be improved and the new community structure match network's natural structure better. In this paper we also show that the detected community structures of online social networks are correlated with users' locations which are identified on Foursquare. This information may also be useful for underlying community detection.

  3. Recruitment and retention of under-represented groups with health disparities into clinical trials: a formative approach.

    Science.gov (United States)

    Harrigan, Rosanne; Perez, Michael H; Beaudry, Steven; Johnson, Crystal; Sil, Payel; Mead, Kau'ionālani; Apau-Ludlum, Noelani

    2014-10-01

    We evaluated the perceived success of recruitment and retention protocols for Native Hawaiian/Pacific Islander/Filipino populations. These three groups were found to have a significantly higher incidence of health disparities than the general population. Training applications of selected vignettes were also generated. Focus groups and questionnaires were used to achieve the objective: identification of themes related to facilitators and deterrents to participation in clinical trials in these populations. This mixed methods approach evaluated promotional materials preferred. Responses to animated videos and vignettes with actors regarding clinical research participation were analyzed. Participants included adults of Hawaiian/Pacific Islander or Filipino ethnicity. Analysis included grounded theory methods, such as constant comparative techniques. The results revealed that attention to the following categories is essential: culturally sensitive knowledge, attitudes, and beliefs related to individuals, families and communities. These themes are recommended as the structure for future interventions to improve participation and retention within these groups.

  4. Spatio-temporal structure, path characteristics and perceptual grouping in immediate serial spatial recall

    Directory of Open Access Journals (Sweden)

    Carlo De Lillo

    2016-11-01

    observer changed dynamically during encoding and recall. This suggested that the effects of structure in spatial span are not dependent on perceptual grouping processes induced by the aerial view of the stimulus array typically afforded by spatial recall tasks. These results demonstrate the independence of coding strategies based on structure from effects of path characteristics and perceptual grouping in immediate serial spatial recall.

  5. Experimental Study on Temperature Behavior of SC Structures under Pure Bending

    International Nuclear Information System (INIS)

    Ham, K. W.; Lee, K. J.; Park, D. S.; Jeon, J. H.

    2006-01-01

    SC(Steel plate Concrete) module method uses steel plate instead of reinforcing bar and mold in existing RC structure. Steel plate modules are fabricated in advance, installed and poured with concrete in construction field, so construction period is remarkably shortened by SC module technique. In case of existence of temperature gap between internal and external structure surface such as spent fuel storage pool, thermal stress is taken place and as a result of it, structural strength is deteriorated. In this study, we designed three test specimens and several tests with or without temperature heating were conducted to evaluate temperature behavior of SC structures under pure bending loading condition

  6. A typical wave wake from high-speed vessels: its group structure and run-up

    Directory of Open Access Journals (Sweden)

    I. Didenkulova

    2013-02-01

    Full Text Available High-amplitude water waves induced by high-speed vessels are regularly observed in Tallinn Bay, the Baltic Sea, causing intense beach erosion and disturbing marine habitants in the coastal zone. Such a strong impact on the coast may be a result of a certain group structure of the wave wake. In order to understand it, here we present an experimental study of the group structure of these wakes at Pikakari beach, Tallinn Bay. The most energetic vessel waves at this location (100 m from the coast at the water depth 2.7 m have amplitudes of about 1 m and periods of 8–10 s and cause maximum run-up heights on a beach up to 1.4 m. These waves represent frequency modulated packets where the largest and longest waves propagate ahead of other smaller amplitude and period waves. Sometimes the groups of different heights and periods can be separated even within one wave wake event. The wave heights within a wake are well described by the Weibull distribution, which has different parameters for wakes from different vessels. Wave run-up heights can also be described by Weibull distribution and its parameters can be connected to the parameters of the distribution of wave heights 100 m from the coast. Finally, the run-up of individual waves within a packet is studied. It is shown that the specific structure of frequency modulated wave packets, induced by high-speed vessels, leads to a sequence of high wave run-ups at the coast, even when the original wave heights are rather moderate. This feature can be a key to understanding the significant impact on coasts caused by fast vessels.

  7. Structure of a protective epitope of group BStreptococcustype III capsular polysaccharide.

    Science.gov (United States)

    Carboni, Filippo; Adamo, Roberto; Fabbrini, Monica; De Ricco, Riccardo; Cattaneo, Vittorio; Brogioni, Barbara; Veggi, Daniele; Pinto, Vittoria; Passalacqua, Irene; Oldrini, Davide; Rappuoli, Rino; Malito, Enrico; Margarit, Immaculada Y Ros; Berti, Francesco

    2017-05-09

    Despite substantial progress in the prevention of group B Streptococcus (GBS) disease with the introduction of intrapartum antibiotic prophylaxis, this pathogen remains a leading cause of neonatal infection. Capsular polysaccharide conjugate vaccines have been tested in phase I/II clinical studies, showing promise for further development. Mapping of epitopes recognized by protective antibodies is crucial for understanding the mechanism of action of vaccines and for enabling antigen design. In this study, we report the structure of the epitope recognized by a monoclonal antibody with opsonophagocytic activity and representative of the protective response against type III GBS polysaccharide. The structure and the atomic-level interactions were determined by saturation transfer difference (STD)-NMR and X-ray crystallography using oligosaccharides obtained by synthetic and depolymerization procedures. The GBS PSIII epitope is made by six sugars. Four of them derive from two adjacent repeating units of the PSIII backbone and two of them from the branched galactose-sialic acid disaccharide contained in this sequence. The sialic acid residue establishes direct binding interactions with the functional antibody. The crystal structure provides insight into the molecular basis of antibody-carbohydrate interactions and confirms that the conformational epitope is not required for antigen recognition. Understanding the structural basis of immune recognition of capsular polysaccharide epitopes can aid in the design of novel glycoconjugate vaccines.

  8. Structure of the crust beneath Cameroon, West Africa, from the joint inversion of Rayleigh wave group velocities and receiver functions

    Science.gov (United States)

    Tokam, Alain-Pierre K.; Tabod, Charles T.; Nyblade, Andrew A.; Julià, Jordi; Wiens, Douglas A.; Pasyanos, Michael E.

    2010-11-01

    The Cameroon Volcanic Line (CVL) consists of a linear chain of Tertiary to Recent, generally alkaline, volcanoes that do not exhibit an age progression. Here we study crustal structure beneath the CVL and adjacent regions in Cameroon using 1-D shear wave velocity models obtained from the joint inversion of Rayleigh wave group velocities and P-receiver functions for 32 broad-band seismic stations deployed between 2005 January and 2007 February. We find that (1) crustal thickness (35-39km) and velocity structure is similar beneath the CVL and the Pan African Oubanguides Belt to the south of the CVL, (2) crust is thicker (43-48km) under the northern margin of the Congo Craton and is characterized by shear wave velocities >=4.0kms-1 in its lower part and (3) crust is thinner (26-31km) under the Garoua rift and the coastal plain. In addition, a fast velocity layer (Vs of 3.6-3.8kms-1) in the upper crust is found beneath many of the seismic stations. Crustal structure beneath the CVL and the Oubanguides Belt is very similar to Pan African crustal structure in the Mozambique Belt, and therefore it appears not to have been modified significantly by the magmatic activity associated with the CVL. The crust beneath the coastal plain was probably thinned during the opening of the southern Atlantic Ocean, while the crust beneath the Garoua rift was likely thinned during the formation of the Benue Trough in the early Cretaceous. We suggest that the thickened crust and the thick mafic lower crustal layer beneath the northern margin of the Congo Craton may be relict features from a continent-continent collision along this margin during the formation of Gondwana.

  9. Non-stationary random vibration analysis of structures under multiple correlated normal random excitations

    Science.gov (United States)

    Li, Yanbin; Mulani, Sameer B.; Kapania, Rakesh K.; Fei, Qingguo; Wu, Shaoqing

    2017-07-01

    An algorithm that integrates Karhunen-Loeve expansion (KLE) and the finite element method (FEM) is proposed to perform non-stationary random vibration analysis of structures under excitations, represented by multiple random processes that are correlated in both time and spatial domains. In KLE, the auto-covariance functions of random excitations are discretized using orthogonal basis functions. The KLE for multiple correlated random excitations relies on expansions in terms of correlated sets of random variables reflecting the cross-covariance of the random processes. During the response calculations, the eigenfunctions of KLE used to represent excitations are applied as forcing functions to the structure. The proposed algorithm is applied to a 2DOF system, a 2D cantilever beam and a 3D aircraft wing under both stationary and non-stationary correlated random excitations. Two methods are adopted to obtain the structural responses: a) the modal method and b) the direct method. Both the methods provide the statistics of the dynamic response with sufficient accuracy. The structural responses under the same type of correlated random excitations are bounded by the response obtained by perfectly correlated and uncorrelated random excitations. The structural response increases with a decrease in the correlation length and with an increase in the correlation magnitude. The proposed methodology can be applied for the analysis of any complex structure under any type of random excitation.

  10. Group velocity effect on resonant, long-range wake-fields in slow wave structures

    CERN Document Server

    Smirnov, A V

    2002-01-01

    Synchronous wake-fields in a dispersive waveguide are derived in a general explicit form on the basis of a rigorous electro-dynamical approach using Fourier transformations. The fundamental role of group velocity in wake-field propagation, calculation of attenuation, amplitudes, form-factors and loss-factors is analyzed for single bunch radiation. Adiabatic tapering of the waveguide and bunch density variation is taken into account analytically for the time-domain fields. Effects of field 'compression/expansion' and group delays are demonstrated. The role of these effects is discussed for single bunch wake-fields, transient beam loading, BBU and HOMs. A novel waveguide structure with central rf coupling and both positive and negative velocities is proposed. It can be used effectively in both high-energy accelerators and single-section linacs.

  11. Crust and upper mantle structure in the Caribbean region by group velocity tomography and regionalization

    International Nuclear Information System (INIS)

    O'Leary, Gonzalez; Alvarez, L.; Chimera, G.; Panza, G.F.

    2004-04-01

    An overview of the crust and upper mantle structure of the Central America and Caribbean region is presented as a result of the processing of more than 200 seismograms recorded by digital broadband stations from SSSN and GSN seismic networks. By FTAN analysis of the fundamental mode of the Rayleigh waves, group velocity dispersion curves are obtained in the period range from 10 s to 40 s; the error of these measurements varies from 0.06 and 0.10 km/s. From the dispersion curves, seven tomographic maps at different periods and with average spatial resolution of 500 km are obtained. Using the logical combinatorial classification techniques, eight main groups of dispersion curves are determined from the tomographic maps and eleven main regions, each one characterized by one kind of dispersion curves, are identified. The average dispersion curves obtained for each region are extended to 150 s by adding data from the tomographic study of and inverted using a non-linear procedure. As a result of the inversion process, a set of models of the S-wave velocity vs. depth in the crust and upper mantle are found. In six regions, we identify a typically oceanic crust and upper mantle structure, while in the other two the models are consistent with the presence of a continental structure. Two regions, located over the major geological zones of the accretionary crust of the Caribbean region, are characterized by a peculiar crust and upper mantle structure, indicating the presence of lithospheric roots reaching, at least, about 200 km of depth. (author)

  12. Projective structure and integrable geodesic flows on the extension of Bott-Virasoro group

    Directory of Open Access Journals (Sweden)

    Partha Guha

    2004-01-01

    Full Text Available This is a sequel to our paper (Lett. Math. Phys. (2000, triggered from a question posed by Marcel, Ovsienko, and Roger in their paper (1997. In this paper, we show that the multicomponent (or vector Ito equation, modified dispersive water wave equation, and modified dispersionless long wave equation are the geodesic flows with respect to an L2 metric on the semidirect product space Diffs(S1⋉C∞(S1kˆ, where Diffs(S1 is the group of orientation preserving Sobolev Hs diffeomorphisms of the circle. We also study the projective structure associated with the matrix Sturm-Liouville operators on the circle.

  13. Afghanistan's ethnic groups share a Y-chromosomal heritage structured by historical events.

    Directory of Open Access Journals (Sweden)

    Marc Haber

    Full Text Available Afghanistan has held a strategic position throughout history. It has been inhabited since the Paleolithic and later became a crossroad for expanding civilizations and empires. Afghanistan's location, history, and diverse ethnic groups present a unique opportunity to explore how nations and ethnic groups emerged, and how major cultural evolutions and technological developments in human history have influenced modern population structures. In this study we have analyzed, for the first time, the four major ethnic groups in present-day Afghanistan: Hazara, Pashtun, Tajik, and Uzbek, using 52 binary markers and 19 short tandem repeats on the non-recombinant segment of the Y-chromosome. A total of 204 Afghan samples were investigated along with more than 8,500 samples from surrounding populations important to Afghanistan's history through migrations and conquests, including Iranians, Greeks, Indians, Middle Easterners, East Europeans, and East Asians. Our results suggest that all current Afghans largely share a heritage derived from a common unstructured ancestral population that could have emerged during the Neolithic revolution and the formation of the first farming communities. Our results also indicate that inter-Afghan differentiation started during the Bronze Age, probably driven by the formation of the first civilizations in the region. Later migrations and invasions into the region have been assimilated differentially among the ethnic groups, increasing inter-population genetic differences, and giving the Afghans a unique genetic diversity in Central Asia.

  14. Crack formation of steel reinforced concrete structure under stress in construction period

    Directory of Open Access Journals (Sweden)

    Hua Zhu

    2016-03-01

    Full Text Available To obtain deformation rules of steel reinforced concrete structure under stress, this study explored the crack formation in construction period. A novel structure system – steel reinforced concrete structure with shear wall and truss at the bottom was analyzed using on-the-spot test in combination with theoretical simulation analysis with SAP2000 software. It was found that, factors influencing crack formation of steel reinforced concrete structure in construction period included construction load, creep of concrete, shrinkage of concrete, displacement of bond of section steel and concrete as well as leveling. In the construction period, the simulated results and the measured results were highly fitted under the influence of time-variant characteristics such as compressive strength, elasticity modulus, creep and shrinkage. Through processing and analyzing the measured data, we obtained the development rules of crack formation of steel reinforced concrete structure with different strength grades as well as deformation rules of time-varying structure system in construction period, figured out the reason for the difference between the simulated results and the measured results, analyzed the deformation of structural components under stress in construction period and proposed some suggestions. This work is beneficial to ensure safe and high-efficient operation of construction

  15. Novel UDP-GalNAc Derivative Structures Provide Insight into the Donor Specificity of Human Blood Group Glycosyltransferase.

    Science.gov (United States)

    Wagner, Gerd K; Pesnot, Thomas; Palcic, Monica M; Jørgensen, Rene

    2015-12-25

    Two closely related glycosyltransferases are responsible for the final step of the biosynthesis of ABO(H) human blood group A and B antigens. The two enzymes differ by only four amino acid residues, which determine whether the enzymes transfer GalNAc from UDP-GalNAc or Gal from UDP-Gal to the H-antigen acceptor. The enzymes belong to the class of GT-A folded enzymes, grouped as GT6 in the CAZy database, and are characterized by a single domain with a metal dependent retaining reaction mechanism. However, the exact role of the four amino acid residues in the specificity of the enzymes is still unresolved. In this study, we report the first structural information of a dual specificity cis-AB blood group glycosyltransferase in complex with a synthetic UDP-GalNAc derivative. Interestingly, the GalNAc moiety adopts an unusual yet catalytically productive conformation in the binding pocket, which is different from the "tucked under" conformation previously observed for the UDP-Gal donor. In addition, we show that this UDP-GalNAc derivative in complex with the H-antigen acceptor provokes the same unusual binding pocket closure as seen for the corresponding UDP-Gal derivative. Despite this, the two derivatives show vastly different kinetic properties. Our results provide a important structural insight into the donor substrate specificity and utilization in blood group biosynthesis, which can very likely be exploited for the development of new glycosyltransferase inhibitors and probes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Review of parameters influencing the structural response of a submerged body under cavitation conditions

    International Nuclear Information System (INIS)

    Escaler, X; De La Torre, O; Farhat, M

    2015-01-01

    Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed. (paper)

  17. Review of parameters influencing the structural response of a submerged body under cavitation conditions

    Science.gov (United States)

    Escaler, X.; De La Torre, O.; Farhat, M.

    2015-12-01

    Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed.

  18. Under-vaccinated groups in Europe and their beliefs, attitudes and reasons for non-vaccination; two systematic reviews.

    Science.gov (United States)

    Fournet, N; Mollema, L; Ruijs, W L; Harmsen, I A; Keck, F; Durand, J Y; Cunha, M P; Wamsiedel, M; Reis, R; French, J; Smit, E G; Kitching, A; van Steenbergen, J E

    2018-01-30

    Despite effective national immunisation programmes in Europe, some groups remain incompletely or un-vaccinated ('under-vaccinated'), with underserved minorities and certain religious/ideological groups repeatedly being involved in outbreaks of vaccine preventable diseases (VPD). Gaining insight into factors regarding acceptance of vaccination of 'under-vaccinated groups' (UVGs) might give opportunities to communicate with them in a trusty and reliable manner that respects their belief system and that, maybe, increase vaccination uptake. We aimed to identify and describe UVGs in Europe and to describe beliefs, attitudes and reasons for non-vaccination in the identified UVGs. We defined a UVG as a group of persons who share the same beliefs and/or live in socially close-knit communities in Europe and who have/had historically low vaccination coverage and/or experienced outbreaks of VPDs since 1950. We searched MEDLINE, EMBASE and PsycINFO databases using specific search term combinations. For the first systematic review, studies that described a group in Europe with an outbreak or low vaccination coverage for a VPD were selected and for the second systematic review, studies that described possible factors that are associated with non-vaccination in these groups were selected. We selected 48 articles out of 606 and 13 articles out of 406 from the first and second search, respectively. Five UVGs were identified in the literature: Orthodox Protestant communities, Anthroposophists, Roma, Irish Travellers, and Orthodox Jewish communities. The main reported factors regarding vaccination were perceived non-severity of traditional "childhood" diseases, fear of vaccine side-effects, and need for more information about for example risk of vaccination. Within each UVG identified, there are a variety of health beliefs and objections to vaccination. In addition, similar factors are shared by several of these groups. Communication strategies regarding these similar factors such as

  19. Aryldithioethyloxycarbonyl (Ardec): a new family of amine protecting groups removable under mild reducing conditions and their applications to peptide synthesis.

    Science.gov (United States)

    Lapeyre, Milaine; Leprince, Jérôme; Massonneau, Marc; Oulyadi, Hassan; Renard, Pierre-Yves; Romieu, Anthony; Turcatti, Gerardo; Vaudry, Hubert

    2006-04-24

    The development of phenyldithioethyloxycarbonyl (Phdec) and 2-pyridyldithioethyloxycarbonyl (Pydec) protecting groups, which are thiol-labile urethanes, is described. These new disulfide-based protecting groups were introduced onto the epsilon-amino group of L-lysine; the resulting amino acid derivatives were easily converted into N alpha-Fmoc building blocks suitable for both solid- and solution-phase peptide synthesis. Model dipeptide(Ardec)s were prepared by using classical peptide couplings followed by standard deprotection protocols. They were used to optimize the conditions for complete thiolytic removal of the Ardec groups both in aqueous and organic media. Phdec and Pydec were found to be cleaved within 15 to 30 min under mild reducing conditions: i) by treatment with dithiothreitol or beta-mercaptoethanol in Tris.HCl buffer (pH 8.5-9.0) for deprotection in water and ii) by treatment with beta-mercaptoethanol and 1,8-diazobicyclo[5.4.0]undec-7-ene (DBU) in N-methylpyrrolidinone for deprotection in an organic medium. Successful solid-phase synthesis of hexapeptides Ac-Lys-Asp-Glu-Val-Asp-Lys(Ardec)-NH2 has clearly demonstrated the full orthogonality of these new amino protecting groups with Fmoc and Boc protections. The utility of the Ardec orthogonal deprotection strategy for site-specific chemical modification of peptides bearing several amino groups was illustrated firstly by the preparation of a fluorogenic substrate for caspase-3 protease containing the cyanine dyes Cy 3.0 and Cy 5.0 as FRET donor/acceptor pair, and by solid-phase synthesis of an hexapeptide bearing a single biotin reporter group.

  20. Dancing multiplicity states supported by a carboxylated group in dicopper structures bonded to O2

    KAUST Repository

    Poater, Albert

    2013-01-29

    The present study pretends to assign the correct multiplicity state to dinuclear copper complexes when interacting with free molecular oxygen. Recently, the formation of a bridge butterfly μ-η2: η2-peroxo dicopper core structure stabilized by the direct interaction of the counterion, a carboxylate group that allows the double bridge linking both metal-centre atoms, was characterized by crystallography. This system was assigned as a diradical singlet with Ms = 0. However, after new calculations it has turned out to be triplet (Ms = 1) despite the stabilization for this latter multiplicity state is not high. Here, the factors that contribute to make this structure display a multiplicity different with respect to the previously expected diradical singlet are described. In the present theoretical study, the roles of the αSp ligand constraints and the counterion are unravelled. On the other hand, the relative stability between the butterfly μ-η2: η2-peroxo structure and the isomeric bis(μ-oxo) species is also on discussion. Despite the relative stabilities of all these either structural or electronic isomeric species are supposed to depend on the computational method, which is a difficulty to reach a definite conclusion about the nature of the active species, all DFT methods using either pure or not pure DFT functionals here reach the same conclusion, favoring the triplet as the ground state for the butterfly μ-η2: η2-peroxo dicopper core structure, and the bis(μ-oxo) species when removing the benzoate counterion. © Springer-Verlag Berlin Heidelberg 2013.

  1. Crystal structure of tarocystatin-papain complex: implications for the inhibition property of group-2 phytocystatins.

    Science.gov (United States)

    Chu, Ming-Hung; Liu, Kai-Lun; Wu, Hsin-Yi; Yeh, Kai-Wun; Cheng, Yi-Sheng

    2011-08-01

    Tarocystatin (CeCPI) from taro (Colocasia esculenta cv. Kaohsiung no. 1), a group-2 phytocystatin, shares a conserved N-terminal cystatin domain (NtD) with other phytocystatins but contains a C-terminal cystatin-like extension (CtE). The structure of the tarocystatin-papain complex and the domain interaction between NtD and CtE in tarocystatin have not been determined. We resolved the crystal structure of the phytocystatin-papain complex at resolution 2.03 Å. Surprisingly, the structure of the NtD-papain complex in a stoichiometry of 1:1 could be built, with no CtE observed. Only two remnant residues of CtE could be built in the structure of the CtE-papain complex. Therefore, CtE is easily digested by papain. To further characterize the interaction between NtD and CtE, three segments of tarocystatin, including the full-length (FL), NtD and CtE, were used to analyze the domain-domain interaction and the inhibition ability. The results from glutaraldehyde cross-linking and yeast two-hybrid assay indicated the existence of an intrinsic flexibility in the region linking NtD and CtE for most tarocystatin molecules. In the inhibition activity assay, the glutathione-S-transferase (GST)-fused FL showed the highest inhibition ability without residual peptidase activity, and GST-NtD and FL showed almost the same inhibition ability, which was higher than with NtD alone. On the basis of the structures, the linker flexibility and inhibition activity of tarocystatins, we propose that the overhangs from the cystatin domain may enhance the inhibition ability of the cystatin domain against papain.

  2. Crystal Structure of the N-terminal Domain of the Group B Streptococcus Alpha C Protein

    Energy Technology Data Exchange (ETDEWEB)

    Auperin,T.; Bolduc, G.; Baron, M.; Heroux, A.; Filman, D.; Madoff, L.; Hogle, J.

    2005-01-01

    Group B Streptococcus (GBS) is the leading cause of bacterial pneumonia, sepsis, and meningitis among neonates and an important cause of morbidity among pregnant women and immunocompromised adults. Invasive diseases due to GBS are attributed to the ability of the pathogen to translocate across human epithelial surfaces. The alpha C protein (ACP) has been identified as an invasin that plays a role in internalization and translocation of GBS across epithelial cells. The soluble N-terminal domain of ACP (NtACP) blocks the internalization of GBS. We determined the 1.86-{angstrom} resolution crystal structure of NtACP comprising residues Ser{sup 52} through Leu{sup 225} of the full-length ACP. NtACP has two domains, an N-terminal {beta}-sandwich and a C-terminal three-helix bundle. Structural and topological alignments reveal that the {beta}-sandwich shares structural elements with the type III fibronectin fold (FnIII), but includes structural elaborations that make it unique. We have identified a potential integrin-binding motif consisting of Lys-Thr-Asp{sup 146}, Arg{sup 110}, and Asp{sup 118}. A similar arrangement of charged residues has been described in other invasins. ACP shows a heparin binding activity that requires NtACP. We propose a possible heparin-binding site, including one surface of the three-helix bundle, and nearby portions of the sandwich and repeat domains. We have validated this prediction using assays of the heparin binding and cell-adhesion properties of engineered fragments of ACP. This is the first crystal structure of a member of the highly conserved Gram-positive surface alpha-like protein family, and it will enable the internalization mechanism of GBS to be dissected at the atomic level.

  3. Reinforced concrete structures under impact and impulsive loading: recent development, problems and trends

    International Nuclear Information System (INIS)

    Plauk, G.; Herter, J.

    1984-01-01

    Nuclear plant facilities and other reinforced concrete structures have to be regarded as to their safety in design and construction with respect to impact and impulsive loading in order to avoid serious damage to mankind and environment. The paper gives a survey on theoretical and experimental developments currently in progress, in particular regarding airplane crash. Some new results arising out of several research programs relevant to particular problems of impact loading have been reviewed and are presented. Experimental investigation for determination of material properties of plain concrete, reinforcing steel as well as steel-concrete bond under high strain-rates are treated in this paper including theoretical approaches for the respective material laws. An outline of soft missile impact tests performed on structural members, e.g. beams and plates, to determine the load deformation or fracture behaviour is given. Furthermore, numerical models and calculations to analyse structural components and structures under impact loading were discussed. (Author) [pt

  4. Theoretical analysis, infrared and structural investigations of energy dissipation in metals under cyclic loading

    International Nuclear Information System (INIS)

    Plekhov, O.A.; Saintier, N.; Palin-Luc, T.; Uvarov, S.V.; Naimark, O.B.

    2007-01-01

    The infrared and structural investigations of energy dissipation processes in metals subjected to cyclic loading have given impetus to the development of a new thermodynamic model with the capability of describing the energy balance under plastic deformation. The model is based on the statistical description of the mesodefect ensemble evolution and its influence on the dissipation ability of the material. Constitutive equations have been formulated for plastic and structural strains, which allow us to describe the stored and dissipated parts of energy under plastic flow. Numerical results indicate that theoretical predictions are in good agreement with the experimentally observed temperature data

  5. Nanomaterials under extreme environments: A study of structural and dynamic properties using reactive molecular dynamics simulations

    Science.gov (United States)

    Shekhar, Adarsh

    Nanotechnology is becoming increasingly important with the continuing advances in experimental techniques. As researchers around the world are trying to expand the current understanding of the behavior of materials at the atomistic scale, the limited resolution of equipment, both in terms of time and space, act as roadblocks to a comprehensive study. Numerical methods, in general and molecular dynamics, in particular act as able compliment to the experiments in our quest for understanding material behavior. In this research work, large scale molecular dynamics simulations to gain insight into the mechano-chemical behavior under extreme conditions of a variety of systems with many real world applications. The body of this work is divided into three parts, each covering a particular system: 1) Aggregates of aluminum nanoparticles are good solid fuel due to high flame propagation rates. Multi-million atom molecular dynamics simulations reveal the mechanism underlying higher reaction rate in a chain of aluminum nanoparticles as compared to an isolated nanoparticle. This is due to the penetration of hot atoms from reacting nanoparticles to an adjacent, unreacted nanoparticle, which brings in external heat and initiates exothermic oxidation reactions. 2) Cavitation bubbles readily occur in fluids subjected to rapid changes in pressure. We use billion-atom reactive molecular dynamics simulations on a 163,840-processor BlueGene/P supercomputer to investigate chemical and mechanical damages caused by shock-induced collapse of nanobubbles in water near amorphous silica. Collapse of an empty nanobubble generates high-speed nanojet, resulting in the formation of a pit on the surface. The pit contains a large number of silanol groups and its volume is found to be directly proportional to the volume of the nanobubble. The gas-filled bubbles undergo partial collapse and consequently the damage on the silica surface is mitigated. 3) The structure and dynamics of water confined in

  6. Structural changes and degradation of Red Latosols under different management systems for 20 years

    Directory of Open Access Journals (Sweden)

    João Tavares Filho

    2014-08-01

    Full Text Available Soils are the foundation of terrestrial ecosystems and their role in food production is fundamental, although physical degradation has been observed in recent years, caused by different cultural practices that modify structures and consequently the functioning of soils. The objective of this study was to evaluate possible structural changes and degradation in an Oxisol under different managements for 20 years: no-tillage cultivation with and without crop rotation, perennial crop and conventional tillage, plus a forested area (reference. Initially, the crop profile was described and subsequently, 10 samples per management system and forest soil were collected to quantify soil organic matter, flocculation degree, bulk density, and macroporosity. The results indicated structural changes down to a soil depth of 50 cm, with predominance of structural units ∆μ (intermediate compaction level under perennial crop and no-tillage crop rotation, and of structural units ∆ (compacted under conventional tillage and no-tillage. The soil was increasingly degraded in the increasing order: forest => no-tillage crop rotation => perennial crop => no-tillage without crop rotation => conventional tillage. In all managements, the values of organic matter and macroporosity were always below and bulk density always above those of the reference area (forest and, under no-tillage crop rotation and perennial crop, the flocculation degree was proportionally equal to that of the reference area.

  7. Multi-stage identification scheme for detecting damage in structures under ambient excitations

    International Nuclear Information System (INIS)

    Bao, Chunxiao; Li, Zhong-Xian; Hao, Hong

    2013-01-01

    Structural damage identification methods are critical to the successful application of structural health monitoring (SHM) systems to civil engineering structures. The dynamic response of civil engineering structures is usually characterized by high nonlinearity and non-stationarity. Accordingly, an improved Hilbert–Huang transform (HHT) method which is adaptive, output-only and applicable to system identification of in-service structures under ambient excitations is developed in this study. Based on this method, a multi-stage damage detection scheme including the detection of damage occurrence, damage existence, damage location and the estimation of damage severity is developed. In this scheme, the improved HHT method is used to analyse the structural acceleration response, the obtained instantaneous frequency detects the instant of damage occurrence, the instantaneous phase is sensitive to minor damage and provides reliable damage indication, and the damage indicator developed based on statistical analysis of the Hilbert marginal spectrum detects damage locations. Finally, the response sampled at the detected damage location is continuously analysed to estimate the damage severity. Numerical and experimental studies of frame structures under ambient excitations are performed. The results demonstrate that this scheme accomplishes the above damage detection functions within one flow. It is robust, time efficient, simply implemented and applicable to the real-time SHM of in-service structures. (paper)

  8. First Principles Prediction of Structure, Structure Selectivity, and Thermodynamic Stability under Realistic Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ceder, Gerbrand [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials and Engineering

    2018-01-28

    Novel materials are often the enabler for new energy technologies. In ab-initio computational materials science, method are developed to predict the behavior of materials starting from the laws of physics, so that properties can be predicted before compounds have to be synthesized and tested. As such, a virtual materials laboratory can be constructed, saving time and money. The objectives of this program were to develop first-principles theory to predict the structure and thermodynamic stability of materials. Since its inception the program focused on the development of the cluster expansion to deal with the increased complexity of complex oxides. This research led to the incorporation of vibrational degrees of freedom in ab-initio thermodynamics, developed methods for multi-component cluster expansions, included the explicit configurational degrees of freedom of localized electrons, developed the formalism for stability in aqueous environments, and culminated in the first ever approach to produce exact ground state predictions of the cluster expansion. Many of these methods have been disseminated to the larger theory community through the Materials Project, pymatgen software, or individual codes. We summarize three of the main accomplishments.

  9. Structural analysis of sheath folds in the Sylacauga Marble Group, Talladega slate belt, southern Appalachians

    Science.gov (United States)

    Mies, J.W.

    1993-01-01

    Remnant blocks of marble from the Moretti-Harrah dimension-stone quarry provide excellent exposure of meter-scale sheath folds. Tubular structures with elliptical cross-sections (4 ???Ryz ??? 5) are the most common expression of the folds. The tubes are elongate subparallel to stretching lineation and are defined by centimeter-scale layers of schist. Eccentrically nested elliptical patterns and opposing asymmetry of folds ('S' and 'Z') are consistent with the sheath-fold interpretation. Sheath folds are locally numerous in the Moretti-Harrah quarry but are not widely distributed in the Sylacauga Marble Group; reconnaissance in neighboring quarries provided no additional observations. The presence of sheath folds in part of the Talladega slate belt indicates a local history of plastic, non-coaxial deformation. Such a history of deformation is substantiated by petrographic study of an extracted hinge from the Moretti-Harrah quarry. The sheath folds are modeled as due to passive amplification of initial structures during simple shear, using both analytic geometry and graphic simulation. As indicated by these models, relatively large shear strains (y ??? 9) and longitudinal initial structures are required. The shear strain presumably relates to NW-directed displacement of overlying crystalline rocks during late Paleozoic orogeny. ?? 1993.

  10. Structure and magnetism in novel group IV element-based magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, Frank [Univ. of North Carolina, Chapel Hill, NC (United States)

    2013-08-14

    The project is to investigate structure, magnetism and spin dependent states of novel group IV element-based magnetic thin films and heterostructures as a function of composition and epitaxial constraints. The materials systems of interest are Si-compatible epitaxial films and heterostructures of Si/Ge-based magnetic ternary alloys grown by non-equilibrium molecular beam epitaxy (MBE) techniques, specifically doped magnetic semiconductors (DMS) and half-metallic Heusler alloys. Systematic structural, chemical, magnetic, and electrical measurements are carried out, using x-ray microbeam techniques, magnetotunneling spectroscopy and microscopy, and magnetotransport. The work is aimed at elucidating the nature and interplay between structure, chemical order, magnetism, and spin-dependent states in these novel materials, at developing materials and techniques to realize and control fully spin polarized states, and at exploring fundamental processes that stabilize the epitaxial magnetic nanostructures and control the electronic and magnetic states in these complex materials. Combinatorial approach provides the means for the systematic studies, and the complex nature of the work necessitates this approach.

  11. Mosasauroid phylogeny under multiple phylogenetic methods provides new insights on the evolution of aquatic adaptations in the group.

    Directory of Open Access Journals (Sweden)

    Tiago R Simões

    Full Text Available Mosasauroids were a successful lineage of squamate reptiles (lizards and snakes that radiated during the Late Cretaceous (95-66 million years ago. They can be considered one of the few lineages in the evolutionary history of tetrapods to have acquired a fully aquatic lifestyle, similarly to whales, ichthyosaurs and plesiosaurs. Despite a long history of research on this group, their phylogenetic relationships have only been tested so far using traditional (unweighted maximum parsimony. However, hypotheses of mosasauroid relationships and the recently proposed multiple origins of aquatically adapted pelvic and pedal features in this group can be more thoroughly tested by methods that take into account variation in branch lengths and evolutionary rates. In this study, we present the first mosasauroid phylogenetic analysis performed under different analytical methods, including maximum likelihood, Bayesian inference, and implied weighting maximum parsimony. The results indicate a lack of congruence in the topological position of halisaurines and Dallasaurus. Additionally, the genus Prognathodon is paraphyletic under all hypotheses. Interestingly, a number of traditional mosasauroid clades become weakly supported, or unresolved, under Bayesian analyses. The reduced resolutions in some consensus trees create ambiguities concerning the evolution of fully aquatic pelvic/pedal conditions under many analyses. However, when enough resolution was obtained, reversals of the pelvic/pedal conditions were favoured by parsimony and likelihood ancestral state reconstructions instead of independent origins of aquatic features in mosasauroids. It is concluded that most of the observed discrepancies among the results can be associated with different analytical procedures, but also due to limited postcranial data on halisaurines, yaguarasaurines and Dallasaurus.

  12. Mosasauroid phylogeny under multiple phylogenetic methods provides new insights on the evolution of aquatic adaptations in the group

    Science.gov (United States)

    Vernygora, Oksana; Paparella, Ilaria; Jimenez-Huidobro, Paulina; Caldwell, Michael W.

    2017-01-01

    Mosasauroids were a successful lineage of squamate reptiles (lizards and snakes) that radiated during the Late Cretaceous (95–66 million years ago). They can be considered one of the few lineages in the evolutionary history of tetrapods to have acquired a fully aquatic lifestyle, similarly to whales, ichthyosaurs and plesiosaurs. Despite a long history of research on this group, their phylogenetic relationships have only been tested so far using traditional (unweighted) maximum parsimony. However, hypotheses of mosasauroid relationships and the recently proposed multiple origins of aquatically adapted pelvic and pedal features in this group can be more thoroughly tested by methods that take into account variation in branch lengths and evolutionary rates. In this study, we present the first mosasauroid phylogenetic analysis performed under different analytical methods, including maximum likelihood, Bayesian inference, and implied weighting maximum parsimony. The results indicate a lack of congruence in the topological position of halisaurines and Dallasaurus. Additionally, the genus Prognathodon is paraphyletic under all hypotheses. Interestingly, a number of traditional mosasauroid clades become weakly supported, or unresolved, under Bayesian analyses. The reduced resolutions in some consensus trees create ambiguities concerning the evolution of fully aquatic pelvic/pedal conditions under many analyses. However, when enough resolution was obtained, reversals of the pelvic/pedal conditions were favoured by parsimony and likelihood ancestral state reconstructions instead of independent origins of aquatic features in mosasauroids. It is concluded that most of the observed discrepancies among the results can be associated with different analytical procedures, but also due to limited postcranial data on halisaurines, yaguarasaurines and Dallasaurus. PMID:28467456

  13. Changes in the concentration of sulfhydryl groups in tissues of rats under the influence of gamma-radiation and adeturon

    International Nuclear Information System (INIS)

    Pantev, T.; Bychvarova, K.

    1984-01-01

    The concentration of SH-groups in the spleen, liver and bone marrow in rats was determined using the method of Sedlak and Lindsey. The changes in thiol level have been traced under the single influence of Adeturon and combined influence of radiation with 7,5 Gy and of Adeturon introduced 15 min before radiation. The animals were killed on 30th, 45th and 90th minute after the exerted influence. The control animals had physiological solution introduced. under the single influence of Adeturon there was increase in SH-groups mainly in the bone marrow in later terms after the exerted influence (the 90th minute), while P-SH in the spleen and liver decrease within the same term. The changes of NP-SH in the spleen and liver are opposite in nature. Under the influence of radiation P-SH in the liver and the spleen slightly decrease, while those in the bone marrow considerably increase on the 60th minute. NP-SH abruptly decrease on the 45th minute in the liver, while those in the spleen and bone marrow slightly differentiate from the control values. In animals protected by Adeturon P-SH in the bone marrow increase on the 30th and 45th minute, while those in the spleen decrease on the 90th minute. NP-SH decrease in the liver. The results obtained show that under the influence of Adeturon some changes occur in the level of thiols in tissues of both nonradiated and radiated animals

  14. Evaluation of a structured group format memory rehabilitation program for adults following brain injury.

    Science.gov (United States)

    Thickpenny-Davis, Kirsten L; Barker-Collo, Suzanne L

    2007-01-01

    To evaluate the impact of an 8-session structured group format memory rehabilitation program on impaired memory functioning. Adults with traumatic brain injury (N = 10) or cerebral vascular accidents (N = 2). A waitlist control study with pregroup, postgroup, and 1-month follow-up assessments. WECHSLER MEMORY SCALE-REVISED: Neuropsychological assessments of memory (California Verbal Learning Test, Wechsler Memory Scale-Revised logical memory, visual-paired associates, and Rey Complex Figure) and both self-report and significant other report of behaviors indicative of memory difficulties and the use of memory strategies. Participation in the memory group increased participants' knowledge of memory and memory strategies as well as use of memory aids and strategies; reduced behaviors indicative of memory impairment; and had a positive effect on neuropsychological assessments of memory (eg, delayed recall for words and figures). All significant improvements exceeded change experienced by waiting-list controls and were maintained at 1-month follow-up assessment. While extension of the findings is needed, the memory group has a positive impact on both neuropsychological measures of memory and everyday memory functioning.

  15. Conceptions of perfectionism and interpersonal problems: evaluating groups using the structural summary method for circumplex data.

    Science.gov (United States)

    Slaney, Robert B; Pincus, Aaron L; Uliaszek, Amanda A; Wang, Kenneth T

    2006-06-01

    This study examined two conceptions of perfectionism in relation to interpersonal problems. Two hundred and seventy-nine undergraduate participants completed the Almost Perfect Scale-Revised (APS-R) and the Dyadic Almost Perfect Scale (DAPS). The authors used empirically derived discriminant functions (APS-R) and cluster analysis (DAPS) to identify three groups for both measures: adaptive and maladaptive perfectionists and nonperfectionists. Analyses of group profiles were performed on the Inventory of Interpersonal Problems Circumplex (IIP-C) scales using the structural summary method for circumplex data. APS-R and DAPS groups were compared on interpersonal problems endorsement and IIP-C profile characteristics. For both measures, results supported the hypotheses that maladaptive perfectionists would exhibit elevated profiles reflecting hostile-dominant and friendly-submissive interpersonal problems, whereas the adaptive perfectionists would exhibit low profile elevation indicative of interpersonal adjustment. Overall, results supported Slaney and colleagues' (2001) model of perfectionism and provided evidence for the validity of the APS-R and DAPS.

  16. Improving learning and confidence through small group, structured otoscopy teaching: a prospective interventional study.

    Science.gov (United States)

    You, Peng; Chahine, Saad; Husein, Murad

    2017-12-28

    Otologic diseases are common and associated with significant health care costs. While accurate diagnosis relies on physical exam, existing studies have highlighted a lack of comfort among trainees with regards to otoscopy. As such, dedicated otoscopy teaching time was incorporated into the undergraduate medical curriculum in the form of a small group teaching session. In this study, we aimed to examine the effect of a small-group, structured teaching session on medical students' confidence with and learning of otoscopic examination. Using a prospective study design, an otolaryngologist delivered an one-hour, small group workshop to medical learners. The workshop included introduction and demonstration of otoscopy and pneumatic otoscopy followed by practice with peer feedback. A survey exploring students' confidence with otoscopy and recall of anatomical landmarks was distributed before(T1), immediately after(T2), and 1 month following the session(T3). One hundred and twenty five learners participated from February 2016 to February 2017. Forty nine participants with complete data over T1-T3 demonstrated significant improvement over time in confidence (Wilk's lambda = .09, F(2,48) = 253.31 p learning (Wilk's lambda = 0.34, F(2,47) = 24.87 p confidence with otoscopy and identification of otologic landmarks. Dedicated otoscopy teaching sessions may be a beneficial addition to the undergraduate medical curriculum.

  17. Structural Variety and Adsorptive Properties of Mesoporous Silicas with Immobilized Oligosaccharide Groups

    Science.gov (United States)

    Trofymchuk, Iryna; Roik, Nadiia; Belyakova, Lyudmila

    2017-04-01

    In this research, we report on the synthesis of mesoporous silicas with various quantities of immobilized oligosaccharide groups and different pore ordering degree. The hydrothermal co-condensation of tetraethyl orthosilicate and β-cyclodextrin-containing organosilane in the presence of cetyltrimethylammonium bromide template was employed. The purpose of this investigation was to show the opportunity of increasing β-cyclodextrin content in silica matrix by changing the molar ratio of initial reagents during organosilane synthesis and to determine whether the enhancing of immobilized groups on the surface influences on model aromatic compound adsorption from water. It was prepared several β-cyclodextrin-organosilanes by modification of (3-aminopropyl)triethoxysilane with oligosaccharide (the molar composition of reaction mixtures were 1:1, 3:1, and 5:1) with using N, N'-carbonyldiimidazole as linking agent. Three types of MCM-41 materials were obtained with 0.018, 0.072, and 0.095 mmol g-1 β-cyclodextrin-group loading according to chemical analysis of silicas. The IR spectroscopy and potentiometric titration were also performed to confirm the presence of functional groups in the silica matrix. Nitrogen sorptometry experiments exhibited the decrease of high surface area (from 812 to 457 m2 g-1) and the average pore diameter (from 1.06 to 0.60 cm3 g-1) of synthesized silicas with increasing of immobilized oligosaccharide groups. The influence of β-cyclodextrin-organosilane presence on the forming of hexagonally arranged porous structure of silicas was evaluated by X-ray diffraction and TEM analyses. As the loading of oligosaccharide groups increases in obtained silicas, the (100) reflex in diffraction patterns is even less intense and broader, denoting the decrease of long-range pore ordering. Adsorption experiments were carried out to study the effect of β-cyclodextrin groups' attendance in silica matrix on benzene uptakes from aqueous solutions. Experimental

  18. Acoustic and Vibration Control for an Underwater Structure under Mechanical Excitation

    Directory of Open Access Journals (Sweden)

    Shi-Jian Zhu

    2014-01-01

    Full Text Available Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, conical shells, and circular bulkheads, of which the motion equations are built with the variational approach, respectively. Acoustic property is analyzed by the Helmholtz integration formulation with boundary element method. Based on negative feedback control algorithm, a control loop with a coupling use of piezoelectric sensor and actuator is built, and accordingly some numerical examples are carried out on active control of structural vibration and acoustic response. Effects of geometrical and material parameters on acoustic and vibration properties are investigated and discussed.

  19. Multi-walled carbon nanotube structural instability with/without metal nanoparticles under electron beam irradiation

    Science.gov (United States)

    Khan, Imran; Huang, Shengli; Wu, Chenxu

    2017-12-01

    The structural transformation of multi-walled carbon nanotubes (MWCNT) under electron beam (e-beam) irradiation at room temperature is studied, with respect to a novel passivation effect due to gold nanoparticles (Au NPs). MWCNT structural evolution induced by energetic e-beam irradiation leads to faster shrinkage, as revealed via in situ transmission electron microscopy, while MWCNT surface modification with Au NPs (Au-MWCNT) slows down the shrinkage by impeding the structural evolution process for a prolonged time under the same irradiation conditions. The new relationship between MWCNT and Au-MWCNT shrinking radii and irradiation time illustrates that the MWCNT shrinkage rate is faster than either theoretical predictions or the same process in Au-MWCNTs. As compared with the outer surface energy (positive curvature), the inner surface energy (negative curvature) of the MWCNT contributes more to the athermal evaporation of tube wall atoms, leading to structural instability and shrinkage under e-beam irradiation. Conversely, Au NPs possess only outer surface energy (positive curvature) compared with the MWCNT. Their presence on MWCNT surfaces retards the dynamics of MWCNT structural evolution by slowing down the evaporation process of carbon atoms, thus restricting Au-MWCNT shrinkage. Au NP interaction and growth evolves athermally on MWCNT surfaces, exhibits increase in their size, and indicates the association of this mechanism with the coalescence induced by e-beam activated electronic excitations. Despite their growth, Au NPs show extreme structural stability, and remain crystalline under prolonged irradiation. It is proposed that the surface energy of MWCNTs and Au NPs, together with e-beam activated soft modes or lattice instability effects, predominantly govern all the above varieties of structural evolution.

  20. Genetic differentiation and population structure of five ethnic groups of Punjab (North-West India).

    Science.gov (United States)

    Singh, Gagandeep; Talwar, Indu; Sharma, Rubina; Matharoo, Kawaljit; Bhanwer, A J S

    2016-12-01

    The state of Punjab in the North-West part of India has acted as the main passage for all the major human invasions into the Indian subcontinent. It has resulted in the mixing of foreign gene pool into the local populations, which led to an extensive range of genetic diversity and has influenced the genetic structure of populations in Punjab, North-West India. The present study was conducted to examine the genetic structure, relationships, and extent of genetic differentiation in five Indo-European speaking ethnic groups of Punjab. A total of 1021 unrelated samples belonging to Banias, Brahmins, Jat Sikhs, Khatris, and Scheduled castes were analyzed for four human-specific Ins/Del polymorphic loci (ACE, APO, PLAT, and D1) and three restriction fragment length polymorphisms ESR (PvuII), LPL (PvuII), and T2 (MspI) using Polymerase chain reaction (PCR). All the loci were found to be polymorphic among the studied populations. The frequency of the Alu insertion at APO locus was observed to exhibit the highest value (82.6-96.3 %), whereas D1 exhibited the lowest (26.5-45.6 %) among all the ethnic groups. The average heterozygosity among the studied populations ranged from 0.3816 in Banias to 0.4163 in Khatris. The F ST values ranged from 0.0418 to 0.0033 for the PLAT and LPL loci, respectively, with an average value being 0.0166. Phylogenetic analysis revealed that Banias and Khatris are genetically closest to each other. The Jat Sikhs are genetically close to Brahmins and are distant from the Banias. The Jat Sikhs, Banias, Brahmins, and Khatris are genetically very distant from the Scheduled castes. Overall, Uniform allele frequency distribution patterns, high average heterozygosity values, and a small degree of genetic differentiation in this study suggest a genetic proximity among the selected populations. A low level of genetic differentiation was observed in the studied population groups indicating that genetic drift might have been small or negligible in shaping

  1. Physiological responses of camel calves to weaning stress with absence of dams under group or individual rearing system

    International Nuclear Information System (INIS)

    Farghaly, H.M.A; Abdel-Fattah, M.S.; Hashem, A.L.S.; Azamel, A.A.

    2012-01-01

    The present study was performed to investigate the effects of weaning stress, rearing system and probiotics supplementation on live body weight, LBW; total feed intake, TFI, water consumption, WC, average daily gain, ADG and growth rate, GR, plasma cortisol and thyroid hormones concentrations during weaning period. This study was carried out at Maryout Research Station of the Desert Research Center, 35 km southwest of Alexandria, Egypt. Ten Maghraby breed camel calves were separated from their dams at 280 days of age with initial LBW of 236.76±0.22 kg. The duration of the study was 35 days and divided into five weeks; first week served as pre-weaning period followed by four weeks served as post-weaning period. Camel calves were weaned using calf-dam contact off system (calves were completely separated from their dams at all times during weaning process) under two rearing systems (6 calves penned in two groups and 4 calves penned in complete isolation, each alone in 4 replicates). Half of calves in each type of rearing system were supplemented with probiotics while the others were not-supplemented with probiotics. The results showed that maternal and milk deprivation affect significantly LBW, TWG, ADG and GR during post-weaning period (28 days), where grouped and isolated calves were different significantly in LBW, TWG and ADG, during the first two weeks post-weaning, but not different significantly in GR (1.66%) at the end of weaning period (28 days). However, grouped calves were more endurance (less responsive) to weaning stress along weaning period. The beneficial effect of probiotics supplementation on TFI was more pronounced from d14 till d28 post-weaning for both grouped and isolated-housed calves. The results showed also that completely social isolation was more pronounced as a stressful condition, this was indicated by the physiological changes which were considered indicative for a higher state of stress, such as an acute release of cortisol hormone and

  2. Optimal Shakedown of the Thin-Wall Metal Structures Under Strength and Stiffness Constraints

    Directory of Open Access Journals (Sweden)

    Alawdin Piotr

    2017-06-01

    Full Text Available Classical optimization problems of metal structures confined mainly with 1st class cross-sections. But in practice it is common to use the cross-sections of higher classes. In this paper, a new mathematical model for described shakedown optimization problem for metal structures, which elements are designed from 1st to 4th class cross-sections, under variable quasi-static loads is presented. The features of limited plastic redistribution of forces in the structure with thin-walled elements there are taken into account. Authors assume the elastic-plastic flexural buckling in one plane without lateral torsional buckling behavior of members. Design formulae for Methods 1 and 2 for members are analyzed. Structures stiffness constrains are also incorporated in order to satisfy the limit serviceability state requirements. With the help of mathematical programming theory and extreme principles the structure optimization algorithm is developed and justified with the numerical experiment for the metal plane frames.

  3. Use of three-dimensional parameters in the analysis of crystal structures under compression

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci

    2007-01-01

    Volume-related parameters of atomic coordinations are an important tool for the analysis of structural changes. Unlike usual tables of bond distances and angles they directly depict three-dimensional properties of coordination polyhedra, and in many instances give more profound structural...... data through use of a procrystal model. For non-regular coordination polyhedra a determination of the point with the minimum variation of distances to the vertices (the centroid of coordination) is a necessary prerequisite for a calculation of the volume-related parameters. The three parameters...... of the coordination polyhedra of cations and the voids that separate them. Analysis of individual compressional characteristics of structural components gives clues for the strong and weak parts of structures under high pressures and paths for structural transformations. The expected behaviour of distortion...

  4. Blast Responses and Vibration of Flood-Defense Structures under High-Intensity Blast Loadings

    Directory of Open Access Journals (Sweden)

    Yonghee Ryu

    2018-01-01

    Full Text Available This study presented the blast behavior of flood-defense structures subjected to high-intensity loadings such as blast shock waves. In order to understand the blast behavior of weir structures, PHAST program was used to predict blast loadings in consideration of material reactivity and congestion levels. Environment factors such as weather data and atmospheric parameters were also considered in this study. Then, nonlinear dynamic analyses were performed using the ABAQUS platform to evaluate structural responses and blast vibration of concrete weir structures subjected to various types of blast loadings, due to uncertainties of the magnitude and durations of blast loads as a function of distance from the explosion. It was shown that the blast damage to concrete weir structure was significantly influenced by congestion levels or material reactivity. Also, the stress concentration under blast loading was observed at the connection area between the concrete weir body and stilling basin.

  5. Probing the local, electronic and magnetic structure of matter under extreme conditions of temperature and pressure

    DEFF Research Database (Denmark)

    Torchio, R.; Boccato, S.; Cerantola, V.

    2016-01-01

    In this paper we present recent achievements in the field of investigation of the local, electronic and magnetic structure of the matter under extreme conditions of pressure and temperature. These results were obtained thanks to the coupling of a compact laser heating system to the energy-dispersive...

  6. Analyses of a steel containment vessel with an outer contact structure under severe internal overpressurization conditions

    International Nuclear Information System (INIS)

    Porter, V.L.

    1994-01-01

    Many Mark-I and Mark-II BWR plants are designed with a steel vessel as the primary containment. Typically, the steel containment vessel (SCV) is enclosed within a reinforced concrete shield building with only a small gap (74-90 mm) separating the two structures. This paper describes finite element analyses performed to evaluate the effects of contact and friction between a steel containment vessel and an outer contact structure when the containment vessel is subjected to large internal pressures. These computations were motivated by a joint program on containment integrity involving the Nuclear Power Engineering Corporation (NUPEC) of Japan, the US Nuclear Regulatory Commission (NRC), and Sandia National Laboratories for testing model containments. Under severe accident loading conditions, the steel containment vessel in a typical Mark-I or Mark-II plant may deform under internal pressurization such that it contacts the inner surface of a shield building wall. (Thermal expansion from increasing accident temperatures would also close the gap between the SCV and the shield building, but temperature effects are not considered in these analyses.) The amount and location of contact and the pressure at which it occurs all affect how the combined structure behaves. A preliminary finite element model has been developed to analyze a model of a typical steel containment vessel con-ling into contact with an outer structure. Both the steel containment vessel and the outer contact structure were modelled with axisymmetric shell finite elements. Of particular interest are the influence that the contact structure has on deformation and potential failure modes of the containment vessel. Furthermore, the coefficient of friction between the two structures was varied to study its effects on the behavior of the containment vessel and on the uplift loads transmitted to the contact structure. These analyses show that the material properties of an outer contact structure and the amount

  7. A novel reduced-complexity group detection structure in MIMO frequency selective fading channels

    KAUST Repository

    Qaraqe, Khalid A.

    2010-09-01

    In this paper a novel reduced complexity detection method named modified symbol flipping method is introduced and its advantages on reducing the burden of the calculations at the receiver compared to the optimum maximum likelihood detection method on multiple input- multiple output frequency selective fading channels are explained. The initial concept of the symbol flipping method is derived from a preliminary detection scheme named bit flipping which was introduced in [1]. The detection structure employed in this paper is ing, detection, and cancellation. On the detection stage, the proposed method is employed and the results are compared to the group maximum likelihood detection scheme proposed in [2]. Simulation results show that a 6 dB performance gain can be achieved at the expense of a slight increase in complexity in comparison with the conventional symbol flipping scheme. © 2010 Crown.

  8. Renormalization-group flow of the effective action of cosmological large-scale structures

    CERN Document Server

    Floerchinger, Stefan

    2017-01-01

    Following an approach of Matarrese and Pietroni, we derive the functional renormalization group (RG) flow of the effective action of cosmological large-scale structures. Perturbative solutions of this RG flow equation are shown to be consistent with standard cosmological perturbation theory. Non-perturbative approximate solutions can be obtained by truncating the a priori infinite set of possible effective actions to a finite subspace. Using for the truncated effective action a form dictated by dissipative fluid dynamics, we derive RG flow equations for the scale dependence of the effective viscosity and sound velocity of non-interacting dark matter, and we solve them numerically. Physically, the effective viscosity and sound velocity account for the interactions of long-wavelength fluctuations with the spectrum of smaller-scale perturbations. We find that the RG flow exhibits an attractor behaviour in the IR that significantly reduces the dependence of the effective viscosity and sound velocity on the input ...

  9. Structure of some relative relation modules of finite p-groups

    International Nuclear Information System (INIS)

    Yamin, M.

    1990-06-01

    Let G be a finite p-group generated by (g i , 1 ≤ i ≤ d), G i the cyclic subgroup generated by g i , E the free product of the G i , 1 ≤ i ≤ d, and S the kernel of the natural epimorphism of E onto G. The largest elementary abelian p-quotient S-circumflex = S/S'S p , regarded as an IF p G-module via conjugation in E, is called a relative relation module of G. If d is the minimum number of generaters for G, the author has proved that S-circumflex is nonprojective and indecomposable. The aim of this paper is to give an alternative proof for the indecomposability of S-circumflex; the proof here is more informative as it deals with Loewy structure and generating sets of S-circumflex and other associated modules. (author). 9 refs

  10. Structure of production costs of different energy sources (fossile fuels and nuclear energy) (group 11)

    International Nuclear Information System (INIS)

    Girard, Ph.

    2002-01-01

    This article is the work of a group of students from the ''Ecole Nationale d'Administration'', they had to study the structure of the costs of the different energy sources. This analysis shows some common features between the energy sources. The cost is very dependent on the partial costs of technological constraints due to exploration, production, transport and distribution. For primary energies the market appears to be not very competitive, the price depends strongly on the market power of the operator and benefits are generally important. In France, taxes play a role to assure competitiveness of gas and coal against oil. Uranium fuel presents the lowest production and transformation costs at the same energy content. Transport costs are important for natural gas which implies a strong mutual dependence between gas producers and consumers. The irreplaceable use of oil in transport assures regular high revenues for oil companies. (A.C.)

  11. Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

    Directory of Open Access Journals (Sweden)

    Lifeng Luan

    2015-01-01

    Full Text Available Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this paper, the nonlinear, explicit, and finite difference program FLAC3D, which considers the mechanical behavior of soil-pile interaction, is used to establish an underconsolidated soil-pile mode. The response processes of the pile side friction force, the pile axial force, and the soil response under seismic load are also analyzed.

  12. Revealing Abrupt and Spontaneous Ruptures of Protein Native Structure under picoNewton Compressive Force Manipulation.

    Science.gov (United States)

    Chowdhury, S Roy; Cao, Jin; He, Yufan; Lu, H Peter

    2018-03-27

    Manipulating protein conformations for exploring protein structure-function relationship has shown great promise. Although protein conformational changes under pulling force manipulation have been extensively studied, protein conformation changes under a compressive force have not been explored quantitatively. The latter is even more biologically significant and relevant in revealing protein functions in living cells associated with protein crowdedness, distribution fluctuations, and cell osmotic stress. Here we report our experimental observations on abrupt ruptures of protein native structures under compressive force, demonstrated and studied by single-molecule AFM-FRET spectroscopic nanoscopy. Our results show that the protein ruptures are abrupt and spontaneous events occurred when the compressive force reaches a threshold of 12-75 pN, a force amplitude accessible from thermal fluctuations in a living cell. The abrupt ruptures are sensitive to local environment, likely a general and important pathway of protein unfolding in living cells.

  13. Structural phase transitions of Ga(Mn)N under high pressure

    Science.gov (United States)

    Sukserm, Akkarach; Pinsook, Udomsilp; Pluengphon, Prayoonsak

    2017-09-01

    Gallium nitride doped with a small concentration of manganese (Ga1-x Mn x N) is one of diluted magnetic semiconductors which can be used for spintronic applications. In this work, Ga31Mn1N32 in the zinc blende (ZB) and rock salt (RS) structures were investigated. We employed the density functional theory (DFT) within the generalized gradient approximation (GGA) to study structural properties, the density of states and the magnetization. The structural phase transitions under pressure up to 60 GPa were also studied. We found that Ga31Mn1N32 in the ZB phase is stable at ambient pressure, and change to the RS phase at about 42 GPa. By using GGA+U, the absolute magnetization is 4.68 μB per cell at 0 GPa. We found also that the absolute magnetization is reduced under pressure.

  14. Evaluation of Soil-Structure Interaction on the Seismic Response of Liquid Storage Tanks under Earthquake Ground Motions

    Directory of Open Access Journals (Sweden)

    Mostafa Farajian

    2017-03-01

    Full Text Available Soil-structure interaction (SSI could affect the seismic response of structures. Since liquid storage tanks are vital structures and must continue their operation under severe earthquakes, their seismic behavior should be studied. Accordingly, the seismic response of two types of steel liquid storage tanks (namely, broad and slender, with aspect ratios of height to radius equal to 0.6 and 1.85 founded on half-space soil is scrutinized under different earthquake ground motions. For a better comparison, the six considered ground motions are classified, based on their pulse-like characteristics, into two groups, named far and near fault ground motions. To model the liquid storage tanks, the simplified mass-spring model is used and the liquid is modeled as two lumped masses known as sloshing and impulsive, and the interaction of fluid and structure is considered using two coupled springs and dashpots. The SSI effect, also, is considered using a coupled spring and dashpot. Additionally, four types of soils are used to consider a wide variety of soil properties. To this end, after deriving the equations of motion, MATLAB programming is employed to obtain the time history responses. Results show that although the SSI effect leads to a decrease in the impulsive displacement, overturning moment, and normalized base shear, the sloshing (or convective displacement is not affected by such effects due to its long period.

  15. Rationalizing the role of structural motif and underlying electronic structure in the finite temperature behavior of atomic clusters

    International Nuclear Information System (INIS)

    Susan, Anju; Joshi, Kavita

    2014-01-01

    Melting in finite size systems is an interesting but complex phenomenon. Many factors affect melting and owing to their interdependencies it is a challenging task to rationalize their roles in the phase transition. In this work, we demonstrate how structural motif of the ground state influences melting transition in small clusters. Here, we report a case with clusters of aluminum and gallium having same number of atoms, valence electrons, and similar structural motif of the ground state but drastically different melting temperatures. We have employed Born-Oppenheimer molecular dynamics to simulate the solid-like to liquid-like transition in these clusters. Our simulations have reproduced the experimental trends fairly well. Further, the detailed analysis of isomers has brought out the role of the ground state structure and underlying electronic structure in the finite temperature behavior of these clusters. For both clusters, isomers accessible before cluster melts have striking similarities and does have strong influence of the structural motif of the ground state. Further, the shape of the heat capacity curve is similar in both the cases but the transition is more spread over for Al 36 which is consistent with the observed isomerization pattern. Our simulations also suggest a way to characterize transition region on the basis of accessibility of the ground state at a specific temperature

  16. Der p 5 Crystal Structure Provides Insight into the Group 5 Dust Mite Allergens

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, G.; Gosavi, R; Krahn, J; Edwards, L; Cuneo, M; Glesner, J; Pomes, A; Chapman, M; London, R; Pedersen, L

    2010-01-01

    Group 5 allergens from house dust mites elicit strong IgE antibody binding in mite-allergic patients. The structure of Der p 5 was determined by x-ray crystallography to better understand the IgE epitopes, to investigate the biologic function in mites, and to compare with the conflicting published Blo t 5 structures, designated 2JMH and 2JRK in the Protein Data Bank. Der p 5 is a three-helical bundle similar to Blo t 5, but the interactions of the helices are more similar to 2JMH than 2JRK. The crystallographic asymmetric unit contains three dimers of Der p 5 that are not exactly alike. Solution scattering techniques were used to assess the multimeric state of Der p 5 in vitro and showed that the predominant state was monomeric, similar to Blo t 5, but larger multimeric species are also present. In the crystal, the formation of the Der p 5 dimer creates a large hydrophobic cavity of {approx}3000 {angstrom}{sup 3} that could be a ligand-binding site. Many allergens are known to bind hydrophobic ligands, which are thought to stimulate the innate immune system and have adjuvant-like effects on IgE-mediated inflammatory responses.

  17. Molecular cloning and protein structure of a human blood group Rh polypeptide

    International Nuclear Information System (INIS)

    Cherif-Zahar, B.; Bloy, C.; Le Van Kim, C.; Blanchard, D.; Bailly, P.; Hermand, P.; Salmon, C.; Cartron, J.P.; Colin, Y.

    1990-01-01

    cDNA clones encoding a human blood group Rh polypeptide were isolated from a human bone marrow cDNA library by using a polymerase chain reaction-amplified DNA fragment encoding the known common N-terminal region of the Rh proteins. The entire primary structure of the Rh polypeptide has been deduced from the nucleotide sequence of a 1384-base-pair-long cDNA clone. Translation of the open reading frame indicates that the Rh protein is composed of 417 amino acids, including the initiator methionine, which is removed in the mature protein, lacks a cleavable N-terminal sequence, and has no consensus site for potential N-glycosylation. The predicted molecular mass of the protein is 45,500, while that estimated for the Rh protein analyzed in NaDodSO 4 /polyacrylamide gels is in the range of 30,000-32,000. These findings suggest either that the hydrophobic Rh protein behaves abnormally on NaDodSO 4 gels or that the Rh mRNA may encode a precursor protein, which is further matured by a proteolytic cleavage of the C-terminal region of the polypeptide. Hydropathy analysis and secondary structure predictions suggest the presence of 13 membrane-spanning domains, indicating that the Rh polypeptide is highly hydrophobic and deeply buried within the phospholipid bilayer. These results suggest that the expression of the Rh gene(s) might be restricted to tissues or cell lines expressing erythroid characters

  18. Group A Streptococcus produce pilus-like structures containing protective antigens and Lancefield T antigens.

    Science.gov (United States)

    Mora, Marirosa; Bensi, Giuliano; Capo, Sabrina; Falugi, Fabiana; Zingaretti, Chiara; Manetti, Andrea G O; Maggi, Tiziana; Taddei, Anna Rita; Grandi, Guido; Telford, John L

    2005-10-25

    Although pili have long been recognized in Gram-negative pathogens as important virulence factors involved in adhesion and invasion, very little is known about extended surface organelles in Gram-positive pathogens. Here we report that Group A Streptococcus (GAS), a Gram-positive human-specific pathogen that causes pharyngitis, impetigo, invasive disease, necrotizing fasciitis, and autoimmune sequelae has long, surface-exposed, pilus-like structures composed of members of a family of extracellular matrix-binding proteins. We describe four variant pili and show that each is recognized by a specific serum of the Lancefield T-typing system, which has been used for over five decades to characterize GAS isolates. Furthermore, we show that immunization of mice with a combination of recombinant pilus proteins confers protection against mucosal challenge with virulent GAS bacteria. The data indicate that induction of a protective immune response against these structures may be a useful strategy for development of a vaccine against disease caused by GAS infection.

  19. Infrared spectra, methyl group structure and internal rotation in some methy - metal compounds

    Science.gov (United States)

    McKean, D. C.; McQuillan, G. P.; Torto, I.; Morrisson, A. R.

    1986-03-01

    Recent and current work on spectra in the CH and CD stretching regions of methyl-metal compounds is reviewed. Free internal rotation with CH force constant variation is found in MMe 3 (M  Ga, Tl) and MMe(CO) 5 (M  Mn, Re) compounds, studied in the gas phase. From solution measurements, no such rotation occurs in CpMMe(CO) 3 (M  Cr,Mo,W) and Cp 2MMe 2 (M  Ti,Zr,Hf), in most of which each methyl group contains two types of CH bond. In each d-subgroup, ν isCH decreases with increasing atomic number, while δ sCH 3 increases. The reverse occurs from Ga to Tl. r oCH values are predicted. There is evidence for the breakdown of the ν isCH/∠HCH correlation, especially in MeTiCl 3 where several features point to an unusual structure of the methyl group.

  20. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    Science.gov (United States)

    Lobato, I.; Rojas, J.; Landauro, C. V.; Torres, J.

    2009-02-01

    The structural evolution and dynamics of silver nanodrops Ag2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 × 1013 K s-1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 × 1012 K s-1), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  1. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    International Nuclear Information System (INIS)

    Lobato, I; Rojas, J; Landauro, C V; Torres, J

    2009-01-01

    The structural evolution and dynamics of silver nanodrops Ag 2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 x 10 13 K s -1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 x 10 12 K s -1 ), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  2. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, I; Rojas, J [Instituto Peruano de EnergIa Nuclear, Avenida Canada 1470, Lima 41 (Peru); Landauro, C V; Torres, J [Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, P.O. box 14-0149, Lima 14 (Peru)], E-mail: jrojast@unmsm.edu.pe

    2009-02-04

    The structural evolution and dynamics of silver nanodrops Ag{sub 2869} (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 x 10{sup 13} K s{sup -1} the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 x 10{sup 12} K s{sup -1}), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  3. CVD growth of graphene under exfoliated hexagonal boron nitride for vertical hybrid structures

    International Nuclear Information System (INIS)

    Wang, Min; Jang, Sung Kyu; Song, Young Jae; Lee, Sungjoo

    2015-01-01

    Graphical abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO2, show the carrier mobility up to approximately 2250 cm 2 V −1 s −1 . The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems. - Abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO 2 , show the carrier mobility up to approximately 2250 cm 2 V −1 s −1 . The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems

  4. Mnemonic transmission, social contagion, and emergence of collective memory: Influence of emotional valence, group structure, and information distribution.

    Science.gov (United States)

    Choi, Hae-Yoon; Kensinger, Elizabeth A; Rajaram, Suparna

    2017-09-01

    Social transmission of memory and its consequence on collective memory have generated enduring interdisciplinary interest because of their widespread significance in interpersonal, sociocultural, and political arenas. We tested the influence of 3 key factors-emotional salience of information, group structure, and information distribution-on mnemonic transmission, social contagion, and collective memory. Participants individually studied emotionally salient (negative or positive) and nonemotional (neutral) picture-word pairs that were completely shared, partially shared, or unshared within participant triads, and then completed 3 consecutive recalls in 1 of 3 conditions: individual-individual-individual (control), collaborative-collaborative (identical group; insular structure)-individual, and collaborative-collaborative (reconfigured group; diverse structure)-individual. Collaboration enhanced negative memories especially in insular group structure and especially for shared information, and promoted collective forgetting of positive memories. Diverse group structure reduced this negativity effect. Unequally distributed information led to social contagion that creates false memories; diverse structure propagated a greater variety of false memories whereas insular structure promoted confidence in false recognition and false collective memory. A simultaneous assessment of network structure, information distribution, and emotional valence breaks new ground to specify how network structure shapes the spread of negative memories and false memories, and the emergence of collective memory. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  5. Evaluation of seismic behavior of soils under nuclear containment structures via dynamic centrifuge test

    International Nuclear Information System (INIS)

    Ha, Jeong Gon; Kim, Dong-Soo

    2014-01-01

    Highlights: • A series of dynamic centrifuge tests were performed for NPP structure to investigate the soil–foundation-structure interaction with various soil conditions from loose sand to weathered rock. • SFSI phenomena for NPP structure were observed directly using experimental method. • Effect of the soil stiffness and nonlinear characteristics on SFSI was estimated. • There are comparisons of the control motions for seismic design of a NPP structure. • Subsoil condition, earthquake intensity and control motion affected to seismic load. - Abstract: To evaluate the earthquake loads for the seismic design of a nuclear containment structure, it is necessary to consider the soil–foundation-structure interaction (SFSI) due to their interdependent behavior. Especially, understanding the effects of soil stiffness under the structure and the location of control motion to SFSI are very important. Motivated by these requirements, a series of dynamic centrifuge tests were performed with various soil conditions from loose sand to weathered rock (WR), as well as different seismic intensities for the bedrock motion. The different amplification characteristics in peak-accelerations profile and effects of soil-nonlinearity in response spectrum were observed. The dynamic behaviors were compared between surface of free-field and foundation of the structure for the evaluation of the control motion for seismic design. It was found that dynamic centrifuge test has potentials to estimate the seismic load considering SFSI

  6. Comparative study of the structural damage of nano-structured and micro-structured ceramics SiC under irradiation

    International Nuclear Information System (INIS)

    Leconte, Y.; Herlin-Boime, N.; Reynaud, C.; Monnet, I.; Levalois, M.; Morales, M.; Portier, X.; Thome, L.

    2006-01-01

    In order to know if the nano-structured ceramics SiC are possible materials for the future nuclear applications, SiC pellets have been submitted to low and mean energy irradiation experiments. These samples have been characterized by grazing X-ray diffraction and confocal Raman spectroscopy as well as conventional SiC ceramic pellets as reference. The low energy irradiations have allowed to exceed the amorphization threshold and to obtain a total disorder in the two types of samples. At the mean energies, this amorphization has not been obtained in spite of the doses generating a number of dpa superior to those of the low energies. The hypothesis of a synergy between the effects of the electronic and nuclear energy losses is advanced. (O.M.)

  7. Numerical and experimental research on annular crossed cable-truss structure under cable rupture

    Science.gov (United States)

    Liu, Renjie; Li, Xiongyan; Xue, Suduo; Mollaert, Marijke; Ye, Jihong

    2017-07-01

    The Annular Crossed Cable-Truss Structure (ACCTS) is a new type of Tensile Spatial Structure with a configuration suitable to cover large-span stadiums. Its configuration has potential to perform well in resisting disproportionate collapse. However, its disproportionate collapse resistance hasn't yet been analyzed in depth. In this study, numerical and experimental research was carried out to investigate the performance of ACCTS under cable rupture. The numerical analysis was done for ten cable-rupture plans using LS-DYNA (explicit method) and the experimental test on an ACCTS with a diameter of 17.15 m was performed for three cable-rupture plans. It is concluded that, while deflections increase with the number of removed cables, an ACCTS does not undergo a disproportionate collapse and it provides a promising structural concept for tensile spatial structures.

  8. Changes in the Structure of a Nigerian Soil under Different Land Management Practices

    Directory of Open Access Journals (Sweden)

    Joshua Olalekan Ogunwole

    2015-06-01

    Full Text Available Quantification of soil physical quality (SPQ and pore size distribution (PSD can assist understanding of how changes in land management practices influence dynamics of soil structure, and this understanding could greatly improve the predictability of soil physical behavior and crop yield. The objectives of this study were to measure the SPQ index under two different land management practices (the continuous arable cropping system and natural bush fallow system, and contrast the effects of these practices on the structure of PSD using soil water retention data. Soil water retention curves obtained from a pressure chamber were fitted to van Genuchten’s equation, setting m (= 1-1/n. Although values for soil bulk density were high, soils under the continuous arable cropping system had good SPQ, and maintained the capacity to support root development. However, soils under the natural bush fallow system had a worse structure than the continuous arable system, with restrictions in available water capacity. These two management systems had different PSDs. Results showed the inferiority of the natural bush fallow system with no traffic restriction (which is the common practice in relation to the continuous arable cropping system in regard to physical quality and structure.

  9. The influence of silicon on barley growth, photosynthesis and ultra-structure under chromium stress.

    Science.gov (United States)

    Ali, Shafaqat; Farooq, Muhammad Ahsan; Yasmeen, Tahira; Hussain, Sabir; Arif, Muhammad Saleem; Abbas, Farhat; Bharwana, Saima Aslam; Zhang, Guoping

    2013-03-01

    Silicon (Si) is generally considered as a benefic element for higher plants, especially for those grown under abiotic stressed environments. Current study is carried out in a hydroponic experiment to analyze the effect of Si application on barley growth, photosynthesis and ultra-structure under chromium (Cr) stress. The treatments consisted of three Si (0, 1 and 2mM) and two Cr (0 and 100 μM) levels. The results showed that Si application at both levels enhanced plant growth relative to the control, and alleviated Cr toxicity, reflected by significant increase in growth and photosynthetic parameters, such as SPAD value, net photosynthetic rate (P(n)), cellular CO(2) concentration (C(i)), stomatal conductance (G(s)) and transpiration rate (T(r)), and chlorophyll fluorescence efficiency (Fv/Fm), with 2mM Si having greater effect than 1mM Si. Cr stress caused ultra-structural disorders in leaves, such as uneven swelling of chloroplast, increased amount of plastoglobuli, disintegrated and disappeared thylakoid membranes, increased size and number of starch granules in leaves, and root ultra-structural modification, including increased vacuolar size, presence of Cr metal in cell walls and vacuoles, disruption and disappearance of nucleus. Exogenous Si alleviated these ultra-structural disorders both in roots and leaves. Apparently, Si and Cr behaved antagonistically, indicating that Si could be a candidate for Cr detoxification in crops under Cr-contaminated soil. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Efficacy of a group-based multimedia HIV prevention intervention for drug-involved women under community supervision: project WORTH.

    Science.gov (United States)

    El-Bassel, Nabila; Gilbert, Louisa; Goddard-Eckrich, Dawn; Chang, Mingway; Wu, Elwin; Hunt, Tim; Epperson, Matt; Shaw, Stacey A; Rowe, Jessica; Almonte, Maria; Witte, Susan

    2014-01-01

    This study is designed to address the need for evidence-based HIV/STI prevention approaches for drug-involved women under criminal justice community supervision. We tested the efficacy of a group-based traditional and multimedia HIV/STI prevention intervention (Project WORTH: Women on the Road to Health) among drug-involved women under community supervision. We randomized 306 women recruited from community supervision settings to receive either: (1) a four-session traditional group-based HIV/STI prevention intervention (traditional WORTH); (2) a four-session multimedia group-based HIV/STI prevention intervention that covered the same content as traditional WORTH but was delivered in a computerized format; or (3) a four-session group-based Wellness Promotion intervention that served as an attention control condition. The study examined whether the traditional or multimedia WORTH intervention was more efficacious in reducing risks when compared to Wellness Promotion; and whether multimedia WORTH was more efficacious in reducing risks when compared to traditional WORTH. Primary outcomes were assessed over the 12-month post-intervention period and included the number of unprotected sex acts, the proportion of protected sex acts, and consistent condom use. At baseline, 77% of participants reported unprotected vaginal or anal sex (n = 237) and 63% (n = 194) had multiple sex partners. Women assigned to traditional or multimedia WORTH were significantly more likely than women assigned to the control condition to report an increase in the proportion of protected sex acts (β = 0.10; 95% CI = 0.02-0.18) and a decrease in the number of unprotected sex acts (IRR = 0.72; 95% CI = 0.57-0.90). The promising effects of traditional and multimedia WORTH on increasing condom use and high participation rates suggest that WORTH may be scaled up to redress the concentrated epidemics of HIV/STIs among drug-involved women in the criminal justice system. Clinical

  11. Quantification of site-city interaction effects on the response of structure under double resonance condition

    Science.gov (United States)

    Kumar, Neeraj; Narayan, Jay Prakash

    2018-01-01

    This paper presents the site-city interaction (SCI) effects on the response of closely spaced structures under double resonance condition (F_{02{{D}}}^{{S}} = F_{02{{D}}}^{{B}}), where F_{02{{D}}}^{{S}} and F_{02{{D}}}^{{B}} are fundamental frequencies of 2-D structure and 2-D basin, respectively. This paper also presents the development of empirical relations to predict the F_{02{{D}}}^{{B}} of elliptical and trapezoidal basins for both the polarizations of the S wave. Simulated results revealed that F_{02{{D}}}^{{B}} of a 2-D basin very much depends on its geometry, shape ratio and polarization of the incident S wave. The obtained spectral amplification factor (SAF) at F_{02{{D}}}^{{S}} of a standalone structure in a 2-D basin is greater than that in the 1-D case under double resonance condition. A considerable reduction of the fundamental resonance frequency of structures due to the SCI effects is observed for both the polarizations of the S wave. The SAFs at F_{02{{D}}}^{{S}} of closely spaced structures due to SCI effects is larger in the case of SV than SH waves. A splitting of the fundamental-mode frequency bandwidth along with the drastic decrease of SAF due to the SCI effects is obtained. The findings of this paper raise the question concerning the validity of the predicted response of standalone structure based on soil-structure interaction for the design of structures in a 2-D small basin, in an urban environment.

  12. Crust and mantle structure under Botswana - the new key-player in African geodynamics?

    Science.gov (United States)

    van der Meijde, M.; Fadel, I.; Paulssen, H.

    2016-12-01

    The 3D crustal and upper mantle structure of Botswana is a major gap in our knowledge about the tectonic evolution of Africa. We will present a new model for crust and upper mantle structure. Our model is based on data from the NARS Botswana and AfricaArray networks, broadband temporary networks in southern Africa (Botswana, Namibia, South Africa and Zambia). The NARS-Botswana seismic network was established to provide broadband recordings in Botswana, covering one of the least studied regions in the world. It is an area that is for a large part covered by the Kalahari sands but also covers the southwestern most branch of the African Rift under the Okavango delta. The goal is to understand how the rifting process and cratonic provinces influence crustal thickness and couple to the underlying mantle. Crust and upper mantle structure, down to the bottom of the mantle transition zone, will be based on receiver function analysis. We observe crustal thicknesses between 35 and 46 km, strongly linked to basins and cratons in the region. The central Kalahari part, which has been previously unstudied, showed some anomalous structure, possibly suggesting melt in the lower crust. The deeper mantle structure shows a discontinuity between 100-150 km depth for a large number of the stations. The mantle transition zone varies in thickness and sharpness of the bounding discontinuities suggesting active dynamical processes underneath Botswana.

  13. Analysis of Structure and Deformation Mechanisms of Mineral Wool Slabs under Compression

    Directory of Open Access Journals (Sweden)

    Laimutis STEPONAITIS

    2012-06-01

    Full Text Available The products of mineral wool are widely used for thermal insulation of buildings, both at construction of new buildings and at renovation of old ones. The mechanical resistance and stability of them, as well as their energy saving and heat saving requirements are in most cases related to the essential specifications of the building. The mechanical characteristics of these products are subject to structure of material, density, content of binder in the product and to technology of production. Subject to the latter, mineral wool products with different fibrous structure are received, therefore, for the structure of each type, the individual structural models are developed attempting to describe the properties of fibrous systems. The deformability of mineral wool products is conditioned by mobility of fibrous structure, which shows up best under compression by short term loads. This study established the impact of various thicknesses and deformations on changes in structure of rock wool products. It also established that the thickness of mineral wool products conditions and influences considerable changes in their structure.DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1926

  14. Lamb Wave-Based Structural Health Monitoring on Composite Bolted Joints under Tensile Load

    Directory of Open Access Journals (Sweden)

    Bin Yang

    2017-06-01

    Full Text Available Online and offline monitoring of composite bolted joints under tensile load were investigated using piezoelectric transducers. The relationships between Lamb wave signals, pre-tightening force, the applied tensile load, as well as the failure modes were investigated. Results indicated that S0/A0 wave amplitudes decrease with the increasing of load. Relationships between damage features and S0/A0 mode were built based on the finite element (FE simulation and experimental results. The possibility of application of Lamb wave-based structure health monitoring in bolted joint-like composite structures was thus achieved.

  15. Impacts of Seed Dispersal on Future Vegetation Structure under Changing Climates

    Science.gov (United States)

    Lee, E.; Schlosser, C. A.; Gao, X.; Prinn, R. G.

    2011-12-01

    As the impacts between land cover change, future climates and ecosystems are expected to be substantial, there are growing needs for improving the capability of simulating the global vegetation structure and landscape as realistically as possible. Current DGVMs assume ubiquitous availability of seeds and do not consider any seed dispersal mechanisms in plant migration process, which may influence the assessment of impacts to the ecosystem that rely on the vegetation structure changes (i.e., change in albedo, runoff, and terrestrial carbon sequestration capacity). This study incorporates time-varying wind-driven seed dispersal (i.e., the SEED configuration) as a dynamic constraint to the migration process of natural vegetation in the Community Land Model (CLM)-DGVM. The SEED configuration is validated using a satellite-derived tree cover dataset. Then the configuration is applied to project future vegetation structures and their implications for carbon fluxes, albedo, and hydrology under two climate mitigation scenarios (No-policy vs. 450ppm CO2 stabilization) for the 21st century. Our results show that regional changes of vegetation structure under changing climates are expected to be significant. For example, Alaska and Siberia are expected to experience substantial shifts of forestry structure, characterized by expansion of needle-leaf boreal forest and shrinkage of C3 grass Arctic. A suggested vulnerability assessment shows that vegetation structures in Alaska, Greenland, Central America, southern South America, East Africa and East Asia are susceptible to changing climates, regardless of the two climate mitigation scenarios. Regions such as Greenland, Tibet, South Asia and Northern Australia, however, may substantially alleviate their risks of rapid change in vegetation structure, given a robust greenhouse gas stabilization target. Proliferation of boreal forests in the high latitudes is expected to amplify the warming trend (i.e., a positive feedback to

  16. Age structure of owned dogs under compulsory culling in a visceral leishmaniasis endemic area

    OpenAIRE

    Bortoletto, Danielly Vieira; Utsunomiya, Yuri Tani; Perri, Silvia Helena Venturoli; Ferreira, Fernando; Nunes, Cáris Maroni

    2016-01-01

    Abstract: The age structure of the dog population is essential for planning and evaluating control programs for zoonotic diseases. We analyzed data of an owned-dog census in order to characterize, for the first time, the structure of a dog population under compulsory culling in a visceral leishmaniasis endemic area (Panorama, São Paulo State, Brazil) that recorded a dog-culling rate of 28% in the year of the study. Data on 1,329 households and 1,671 owned dogs revealed an owned dog:human rati...

  17. Denaturation of collagen structures and their transformation under the physical and chemical effects

    Science.gov (United States)

    Ivankin, A.; Boldirev, V.; Fadeev, G.; Baburina, M.; Kulikovskii, A.; Vostrikova, N.

    2017-11-01

    The process of denaturation of collagen structures under the influence of physical and chemical factors play an important role in the manufacture of food technology and the production of drugs for medicine and cosmetology. The paper discussed the problem of the combined effects of heat treatment, mechanical dispersion and ultrasonic action on the structural changes of the animal collagen in the presence of weak protonated organic acids. Algorithm combined effects of physical and chemical factors as a result of the formation of the technological properties of products containing collagen has been shown.

  18. Morphological features and mechanics of destruction of materials with different structures under impact drop cyclic loading

    Directory of Open Access Journals (Sweden)

    Varavka Valery N.

    2017-01-01

    Full Text Available The process of erosion destruction of steels with austenitic, sorbitol and martensitic structure under the influence of high-speed liquid-drop collisions is studied. The characteristics of the morphological features and mechanisms of the process of surface degradation of steels with different structures are given. Their classification criterion is proposed on the basis of the diagrams of limiting states. Based on the theory of Paris-Erdogan, the computational and analytical model of the fatigue fracture of martensitic steel has been developed.

  19. Structures under crash and impact continuum mechanics, discretization and experimental characterization

    CERN Document Server

    Hiermaier, Stefan

    2007-01-01

    Required reading for those in the relevant areas of work, this book examines the testing and modeling of materials and structures under dynamic loading conditions.Readers get an in-depth analysis of the current mathematical modeling and simulation tools available for a variety of materials, alongside discussions of the benefits and limitations these tools pose in industrial design.The models discussed are also available in commercial codes such as LS-DYNA and AOTODYN.Following a logical and well organized structure, this volume uniquely combines experimental procedures with numerical simulatio

  20. Lamb Wave-Based Structural Health Monitoring on Composite Bolted Joints under Tensile Load

    Science.gov (United States)

    Yang, Bin; Xuan, Fu-Zhen; Xiang, Yanxun; Li, Dan; Zhu, Wujun; Tang, Xiaojun; Xu, Jichao; Yang, Kang; Luo, Chengqiang

    2017-01-01

    Online and offline monitoring of composite bolted joints under tensile load were investigated using piezoelectric transducers. The relationships between Lamb wave signals, pre-tightening force, the applied tensile load, as well as the failure modes were investigated. Results indicated that S0/A0 wave amplitudes decrease with the increasing of load. Relationships between damage features and S0/A0 mode were built based on the finite element (FE) simulation and experimental results. The possibility of application of Lamb wave-based structure health monitoring in bolted joint-like composite structures was thus achieved. PMID:28773014

  1. Structural transformation of CsI thin film photocathodes under exposure to air and UV irradiation

    CERN Document Server

    Tremsin, A S; Siegmund, O H W

    2000-01-01

    Transmission electron microscopy has been employed to study the structure of polycrystalline CsI thin films and its transformation under exposure to humid air and UV irradiation. The catastrophic degradation of CsI thin film photocathode performance is shown to be associated with the film dissolving followed by its re-crystallization. This results in the formation of large lumps of CsI crystal on the substrate surface, so that the film becomes discontinuous and its performance as a photocathode is permanently degraded. No change in the surface morphology and the film crystalline structure was observed after the samples were UV irradiated.

  2. Conformational influence of the ribose 2'-hydroxyl group: crystal structures of DNA-RNA chimeric duplexes

    Science.gov (United States)

    Egli, M.; Usman, N.; Rich, A.

    1993-01-01

    We have crystallized three double-helical DNA-RNA chimeric duplexes and determined their structures by X-ray crystallography at resolutions between 2 and 2.25 A. The two self-complementary duplexes [r(G)d(CGTATACGC)]2 and [d(GCGT)r(A)d(TACGC)]2, as well as the Okazaki fragment d(GGGTATACGC).r(GCG)d(TATACCC), were found to adopt A-type conformations. The crystal structures are non-isomorphous, and the crystallographic environments for the three chimeras are different. A number of intramolecular interactions of the ribose 2'-hydroxyl groups contribute to the stabilization of the A-conformation. Hydrogen bonds between 2'-hydroxyls and 5'-oxygens or phosphate oxygens, in addition to the previously observed hydrogen bonds to 1'-oxygens of adjacent riboses and deoxyriboses, are observed in the DNA-RNA chimeric duplexes. The crystalline chimeric duplexes do not show a transition between the DNA A- and B-conformations. CD spectra suggest that the Okazaki fragment assumes an A-conformation in solution as well. In this molecule the three RNA residues may therefore lock the complete decamer in the A-conformation. Crystals of an all-DNA strand with the same sequence as the self-complementary chimeras show a morphology which is different from those of the chimera crystals. Moreover, the oligonucleotide does not match any of the sequence characteristics of DNAs usually adopting the A-conformation in the crystalline state (e.g., octamers with short alternating stretches of purines and pyrimidines). In DNA-RNA chimeric duplexes, it is therefore possible that a single RNA residue can drive the conformational equilibrium toward the A-conformation.

  3. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

    Science.gov (United States)

    Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

    2017-04-01

    Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

  4. Multi-criteria group decision making for evaluating the performance of e-waste recycling programs under uncertainty.

    Science.gov (United States)

    Wibowo, Santoso; Deng, Hepu

    2015-06-01

    This paper presents a multi-criteria group decision making approach for effectively evaluating the performance of e-waste recycling programs under uncertainty in an organization. Intuitionistic fuzzy numbers are used for adequately representing the subjective and imprecise assessments of the decision makers in evaluating the relative importance of evaluation criteria and the performance of individual e-waste recycling programs with respect to individual criteria in a given situation. An interactive fuzzy multi-criteria decision making algorithm is developed for facilitating consensus building in a group decision making environment to ensure that all the interest of individual decision makers have been appropriately considered in evaluating alternative e-waste recycling programs with respect to their corporate sustainability performance. The developed algorithm is then incorporated into a multi-criteria decision support system for making the overall performance evaluation process effectively and simple to use. Such a multi-criteria decision making system adequately provides organizations with a proactive mechanism for incorporating the concept of corporate sustainability into their regular planning decisions and business practices. An example is presented for demonstrating the applicability of the proposed approach in evaluating the performance of e-waste recycling programs in organizations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Group Decision Making Process for Supplier Selection with TOPSIS Method under Interval-Valued Intuitionistic Fuzzy Numbers

    Directory of Open Access Journals (Sweden)

    Mohammad Izadikhah

    2012-01-01

    Full Text Available Supplier selection is a fundamental issue of supply chain area that heavily contributes to the overall supply chain performance, and, also, it is a hard problem since supplier selection is typically a multicriteria group decision problem. In many practical situations, there usually exists incomplete and uncertain, and the decision makers cannot easily express their judgments on the candidates with exact and crisp values. Therefore, in this paper an extended technique for order preference by similarity to ideal solution (TOPSIS method for group decision making with Atanassov's interval-valued intuitionistic fuzzy numbers is proposed to solve the supplier selection problem under incomplete and uncertain information environment. In other researches in this area, the weights of each decision maker and in many of them the weights of criteria are predetermined, but these weights have been calculated in this paper by using the decision matrix of each decision maker. Also, the normalized Hamming distance is proposed to calculate the distance between Atanassov's interval-valued intuitionistic fuzzy numbers. Finally, a numerical example for supplier selection is given to clarify the main results developed in this paper.

  6. Seismic structure beneath the Gulf of California: a contribution from group velocity measurements

    Science.gov (United States)

    Di Luccio, F.; Persaud, P.; Clayton, R. W.

    2014-12-01

    Rayleigh wave group velocity dispersion measurements from local and regional earthquakes are used to interpret the lithospheric structure in the Gulf of California region. We compute group velocity maps for Rayleigh waves from 10 to 150 s using earthquakes recorded by broad-band stations of the Network of Autonomously Recording Seismographs in Baja California and Mexico mainland, UNM in Mexico, BOR, DPP and GOR in southern California and TUC in Arizona. The study area is gridded in 120 longitude cells by 180 latitude cells, with an equal spacing of 10 × 10 km. Assuming that each gridpoint is laterally homogeneous, for each period the tomographic maps are inverted to produce a 3-D lithospheric shear wave velocity model for the region. Near the Gulf of California rift axis, we found three prominent low shear wave velocity regions, which are associated with mantle upwelling near the Cerro Prieto volcanic field, the Ballenas Transform Fault and the East Pacific Rise. Upwelling of the mantle at lithospheric and asthenospheric depths characterizes most of the Gulf. This more detailed finding is new when compared to previous surface wave studies in the region. A low-velocity zone in northcentral Baja at ˜28ºN which extends east-south-eastwards is interpreted as an asthenospheric window. In addition, we also identify a well-defined high-velocity zone in the upper mantle beneath central-western Baja California, which correlates with the previously interpreted location of the stalled Guadalupe and Magdalena microplates. We interpret locations of the fossil slab and slab window in light of the distribution of unique post-subduction volcanic rocks in the Gulf of California and Baja California. We also observe a high-velocity anomaly at 50-km depth extending down to ˜130 km near the southwestern Baja coastline and beneath Baja, which may represent another remnant of the Farallon slab.

  7. Multi-criteria Group Decision Making Approach for Teacher Recruitment in Higher Education under Simplified Neutrosophic Environment

    Directory of Open Access Journals (Sweden)

    Kalyan Mondal

    2014-12-01

    Full Text Available Teacher recruitment is a multi-criteria group decisionmaking process involving subjectivity, imprecision, and fuzziness that can be suitably represented by neutrosophic sets. Neutrosophic set, a generalization of fuzzy sets is characterized by a truth-membership function, falsity-membership function and an indeterminacy-membership function. These functions are real standard or non-standard subsets of ] 0-, 1+[ .There is no restriction on the sum of the functions, so the sum lies between ]0-, 3+[. A neutrosophic approach is a more general and suitable way to deal with imprecise information, when compared to a fuzzy set. The purpose of this study is to develop a neutrosophic multi-criteria group decision-making model based on hybrid scoreaccuracy functions for teacher recruitment in higher education. Eight criteria obtained from expert opinions are considered for recruitment process. The criteria are namely academic performance index, teaching aptitude, subject knowledge, research experience, leadership quality, personality, management capacity, and personal values. In this paper we use the score and accuracy functions and the hybrid score-accuracy functions of single valued neutrosophic numbers (SVNNs and ranking method for SVNNs. Then, multi-criteria group decision-making method with unknown weights for attributes and incompletely known weights for decision makers is used based on the hybrid score-accuracy functions under single valued neutrosophic environments. We use weight model for attributes based on the hybrid score-accuracy functions to derive the weights of decision makers and attributes from the decision matrices represented by the form of SVNNs to decrease the effect of some unreasonable evaluations. Moreover, we use the overall evaluation formulae of the weighted hybrid scoreaccuracy functions for each alternative to rank the alternatives and recruit the most desirable teachers. Finally, an educational problem for teacher selection is

  8. Medulloblastoma Down Under 2013: a report from the third annual meeting of the International Medulloblastoma Working Group.

    Science.gov (United States)

    Gottardo, Nicholas G; Hansford, Jordan R; McGlade, Jacqueline P; Alvaro, Frank; Ashley, David M; Bailey, Simon; Baker, David L; Bourdeaut, Franck; Cho, Yoon-Jae; Clay, Moira; Clifford, Steven C; Cohn, Richard J; Cole, Catherine H; Dallas, Peter B; Downie, Peter; Doz, François; Ellison, David W; Endersby, Raelene; Fisher, Paul G; Hassall, Timothy; Heath, John A; Hii, Hilary L; Jones, David T W; Junckerstorff, Reimar; Kellie, Stewart; Kool, Marcel; Kotecha, Rishi S; Lichter, Peter; Laughton, Stephen J; Lee, Sharon; McCowage, Geoff; Northcott, Paul A; Olson, James M; Packer, Roger J; Pfister, Stefan M; Pietsch, Torsten; Pizer, Barry; Pomeroy, Scott L; Remke, Marc; Robinson, Giles W; Rutkowski, Stefan; Schoep, Tobias; Shelat, Anang A; Stewart, Clinton F; Sullivan, Michael; Taylor, Michael D; Wainwright, Brandon; Walwyn, Thomas; Weiss, William A; Williamson, Dan; Gajjar, Amar

    2014-02-01

    Medulloblastoma is curable in approximately 70% of patients. Over the past decade, progress in improving survival using conventional therapies has stalled, resulting in reduced quality of life due to treatment-related side effects, which are a major concern in survivors. The vast amount of genomic and molecular data generated over the last 5-10 years encourages optimism that improved risk stratification and new molecular targets will improve outcomes. It is now clear that medulloblastoma is not a single-disease entity, but instead consists of at least four distinct molecular subgroups: WNT/Wingless, Sonic Hedgehog, Group 3, and Group 4. The Medulloblastoma Down Under 2013 meeting, which convened at Bunker Bay, Australia, brought together 50 leading clinicians and scientists. The 2-day agenda included focused sessions on pathology and molecular stratification, genomics and mouse models, high-throughput drug screening, and clinical trial design. The meeting established a global action plan to translate novel biologic insights and drug targeting into treatment regimens to improve outcomes. A consensus was reached in several key areas, with the most important being that a novel classification scheme for medulloblastoma based on the four molecular subgroups, as well as histopathologic features, should be presented for consideration in the upcoming fifth edition of the World Health Organization's classification of tumours of the central nervous system. Three other notable areas of agreement were as follows: (1) to establish a central repository of annotated mouse models that are readily accessible and freely available to the international research community; (2) to institute common eligibility criteria between the Children's Oncology Group and the International Society of Paediatric Oncology Europe and initiate joint or parallel clinical trials; (3) to share preliminary high-throughput screening data across discovery labs to hasten the development of novel therapeutics

  9. LOAD CARRYING CAPABILITY OF LIQUID FILLED CYLINDRICAL SHELL STRUCTURES UNDER AXIAL COMPRESSION

    Directory of Open Access Journals (Sweden)

    QASIM H. SHAH

    2011-08-01

    Full Text Available Empty and water filled cylindrical Tin (Sn coated steel cans were loaded under axial compression at varying loading rates to study their resistance to withstand accidental loads. Compared to empty cans the water filled cans exhibit greater resistance to axially applied compression loads before a complete collapse. The time and load or stroke and load plots showed three significant load peaks related to three stages during loading until the cylinder collapse. First peak corresponds to the initial structural buckling of can. Second peak occurs when cylindrical can walls gradually come into full contact with water. The third peak shows the maximum load carrying capability of the structure where pressurized water deforms the can walls into curved shape until can walls fail under peak pressure. The collapse process of water filled cylindrical shell was further studied using Smooth Particle Hydrodynamics (SPH technique in LSDYNA. Load peaks observed in the experimental work were successfully simulated which substantiated the experimental work.

  10. Pricing Decision under Dual-Channel Structure considering Fairness and Free-Riding Behavior

    Directory of Open Access Journals (Sweden)

    Yongmei Liu

    2014-01-01

    Full Text Available Under dual-channel structure, the free-riding behavior based on different service levels between online channel and offline channel cannot be avoided, which would lead to channel unfairness. This study implies that the dual-channel supply chain is built up by online channel controlled by manufacturer and traditional channel controlled by retailer, respectively. Under this channel structure, we rebuild the linear demand function considering free-riding behavior and modify the pricing model based on channel fairness. Then the influences of fair factor and free-riding behavior on manufacturer and retailer pricing and performance are discussed. Finally, we propose some numerical analysis to provide some valuable recommendations for manufacturer and retailer improving channel management performance.

  11. Group structure of Guiana dolphins, Sotalia guianensis (Cetacea, Delphinidae in Ilha Grande Bay, Rio de Janeiro, southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Rodrigo Tardin

    2013-04-01

    Full Text Available Cetaceans present a group structure of great complexity and display a wide behavioral plasticity. Many efforts have been made to understand the group structures of the various species, however, this type of information is still lacking for some species. Therefore, our objectives were to 1 characterize the structure of the Sotalia guianensis groups in Ilha Grande Bay, Rio de Janeiro, Brazil, and 2 investigate how both behavior and season influence the group structure of this population. This species is considered "data deficient" by the IUCN. We conducted 28 boat trips using group focal procedures, and a total of 1,314 groups were observed. Of these groups, 1,268 (94.4% contained calves, the largest percentage ever reported for the species. Groups with calves were larger than those without them, suggesting a strategy to protect these individuals with underdeveloped physiology. The mean group sizes reached 17.6 ± 18.3 individuals. Within these groups, we observed that both behavior (H = 112.5, d.f. = 2, P < 0.05 and season (number of simulations: 10,000; sample size of fall-winter = 544; sample size of spring-summer = 684; P < 0.05, demonstrated a statistically significant influence. The most common degree of cohesion was mixed, and cohesion also varied with behavior (χ2 = 10.1, P < 0.05 and season (χ2 = 31.0, P < 0.05. This paper contributes towards understanding the highly variable nature of S. guianensis group dynamics. These data may be important in understanding the structure of groups in a site that is being increasingly impacted by different human activities. Moreover, this area contains the largest aggregation ever observed for this species and may therefore represent an important source of genetic diversity for the species as a whole.

  12. Reliability of functioning and reserves of system, controlling movements with different coordination structure of special health group girl students in physical education process

    Directory of Open Access Journals (Sweden)

    A.A. Pryimakov

    2017-04-01

    Full Text Available Purpose: to study reliability of functioning and reserves of system, controlling movements with different coordination structure of special health group girl students (low health level in physical education process. Material: in the research special health group girl students (n=136, age 17-19 participated. They were divided into 2 groups - control and experimental. The program, directed to increase reliability and reserves of system controlling movements, was realized. It was based on physical exercises of complicated coordination with novelty elements, which were fulfilled under musical accompaniment. The research continued one academic year. Results: in girl students with health problems we registered higher differential thresholds, when reproducing local movements in complicated conditions. They used visual and hearing feedback channels for informing brain’s programming areas about made mistakes. They were worse teachable in training accurate movements. These girl students have less expressed compensation reserves under impact of hindering factors and interferences. It can be interpreted as non-specific crisscross negative response to motor functional system in case of health problems. All these determine reduction of reserve potentials of motor control system. Conclusions: The main reserve potentials’ criteria of control over different coordination structure movements are: quickness of passing to program mechanism of fine movements’ regulation in stable conditions of functioning; power and effectiveness of compensatory reactions, ensuring interference immunity of system, controlling movements under interfering factors; reliability of maintaining movements’ qualitative parameters in optimal range under interfering factors; reduction of sensor interconnections in stable functioning conditions.

  13. Investment certificates under German taxation: Benefit or burden for structured products' performance?

    OpenAIRE

    Scholz, Peter; Walther, Ursula

    2010-01-01

    Despite their impressive market success, investment certificates' benefits are puzzling from both a theoretical and an empirical viewpoint. Previous research analyzed portfoliotheoretical issues, mispricing patterns, and counterparty risk. This work highlights the impact of taxation, which has not been previously addressed for these instruments. In order to capture tax effects, we simulate the entire return distributions of several structured products under the two most recent German taxation...

  14. The structural variation of phytoplankton in the Gulf of Riga under the influence of environmental factors

    OpenAIRE

    Jurgensone, Iveta

    2011-01-01

    „The structural variation of phytoplankton in the Gulf of Riga under the influence of environmental factors.” Trends of phytoplankton (1976-2008) from the Gulf of Riga and the related environmental factors are investigated. Phytoplankton response to riverine DOM and nutrient increase was tested and the effect on the pelagic food web assessed. Changes in the winter-spring DIN/DIP ratio cause shift from diatoms to cyanobacteria. Dinoflagellate biomass remains constant after temperature excee...

  15. Inelastic behavior of materials and structures under monotonic and cyclic loading

    CERN Document Server

    Brünig, Michael

    2015-01-01

    This book presents studies on the inelastic behavior of materials and structures under monotonic and cyclic loads. It focuses on the description of new effects like purely thermal cycles or cases of non-trivial damages. The various models are based on different approaches and methods and scaling aspects are taken into account. In addition to purely phenomenological models, the book also presents mechanisms-based approaches. It includes contributions written by leading authors from a host of different countries.

  16. Quantitative analysis of composition, structure and features of hemoglobin under the influence of radiation in vivo

    International Nuclear Information System (INIS)

    Kurbanov, F.F.; Mamedov, T.G.; Abdullaev, Kh.D.; Akhmedov, N.A.; Manojlov, S.K.

    1995-01-01

    The literature data on the changes in composition, structure and properties of hemoglobin under the influence of ionizing radiation in vivo are reviewed. The algorithm of calculation of damaged hemoglobin molecule percentage is proposed. Four main realizations of radiation-chemical damage are considered. By the algorithm the estimation of the damaged molecules percentage resulted from the exposure to 10 Gy is given. Hemoglobin radiation damage is considered as one of the most important mechanisms triggering radiation sickness. 11 refs

  17. Aza-macrocyclic complexes of the Group 1 cations - synthesis, structures and density functional theory study.

    Science.gov (United States)

    Dyke, John; Levason, William; Light, Mark E; Pugh, David; Reid, Gillian; Bhakhoa, Hanusha; Ramasami, Ponnadurai; Rhyman, Lydia

    2015-08-21

    The Group 1 complexes, [M(Me6[18]aneN6)][BAr(F)] (M = Li-Cs; Me6[18]aneN6 = 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane; BAr(F) = tetrakis{3,5-bis(trifluoromethyl)-phenyl}borate), are obtained in high yield by reaction of the macrocycle with M[BAr(F)] in anhydrous CH2Cl2 solution, and characterised spectroscopically ((1)H, (13)C{(1)H}, (7)Li, (23)Na, and (133)Cs NMR), by microanalysis and, for M = Li, K, and Rb, by single crystal X-ray analysis. The structures show N6-coordination to the metal ion; the small ionic radius for Li(+) leads to a puckered conformation. In contrast, the K(+) ion fits well into the N6 plane, with the [BAr(F)](-) anions above and below, leading to two K(+) species in the asymmetric unit (a hexagonal planar [K(Me6[18]aneN6)](+) cation and a '[K(Me6[18]aneN6)(κ(1)-BAr(F))2](-) anion', with long axial KF interactions). The Rb(+) ion sits above the N6 plane, with two long axial RbF interactions in one cation and two long, mutually cis RbF interactions in the other. The unusual sandwich cations, [M(Me3tacn)2](+) (M = Na, K; distorted octahedral, N6 donor set) and half-sandwich cations [Li(Me3tacn)(thf)](+) (distorted tetrahedron, N3O donor set), [Li(Me4cyclen)(OH2)](+), and [Na(Me4cyclen)(thf)](+) (both distorted square pyramids with N4O donor sets) were also prepared (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, Me4cyclen = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane). Density functional theory (DFT) calculations, using the BP86 and B3LYP functionals, show that the accessibility of the [M(Me3tacn)2](+) sandwich cations depends strongly on the M(+) ionic radius, such that it is sufficiently large to avoid steric clashing between the Me groups of the two rings, and small enough to avoid very acute N-M-N chelate angles. The calculations also show that coordination to the Group 1 cation involves significant donation of electron density from the p-orbitals on the N atoms of the macrocycle, rather than purely

  18. Structural, absorption, and molecular properties of o,o'-dihydroxyazo resorcinol dyes bearing an acryloyloxy group

    Science.gov (United States)

    Özkınalı, Sevil; Çavuş, M. Serdar; Ceylan, Abdullah; Gür, Mahmut

    2017-12-01

    To the best of our knowledge, this is the first study reporting the synthesis and characterization of o,o‧-dihydroxyazo dyes bearing an acryloyl group. The o,o‧-dihydroxyazo dyes were synthesized through coupling of resorcinol with the diazonium salts of 2-amino-4-methylphenol, 2-aminophenol, 2-amino-4-chlorophenol, and 2-amino-4-nitrophenol. Their acryloyl derivatives were synthesized using metallic sodium and acryloyl chloride under an inert atmosphere. Characterization of the compounds was conducted using infrared (IR), ultraviolet-visible (UV-vis), proton nuclear magnetic resonance (1H NMR), and carbon nuclear magnetic resonance (13C NMR) spectroscopic methods. The tautomerism of the synthesized compounds' was also evaluated. The results were compared with theoretical results obtained by density functional theory (DFT). The DFT calculations were performed to obtain ground-state optimized geometries and calculate the relevant electronic and chemical reactivity parameters. Furthermore, possible tautomers deduced from the UV-vis spectra were investigated using theoretical calculations. Both the IR and NMR spectral data showed that azo tautomers predominate in the solid state and DMSO solvent. The effects of pH, solvent, and substituent on the predominant tautomers were further investigated through UV-vis spectroscopy. The results indicate that hydrazone tautomers were dominant at pH 12 in dimethylformamide (DMF), whereas azo tautomers were dominant at pH 2 in EtOH or CHCl3.

  19. The Potamophylax nigricornis group (Trichoptera, Limnephilidae: resolution of phylogenetic species by fine structure analysis

    Directory of Open Access Journals (Sweden)

    Oláh, J.

    2013-11-01

    Full Text Available Applying the phylogenetic species concept and the sexual selection theory we have reviewed some natal aspects of incipient species and their accelerated evolution. How can we recognise early stages of divergence? Which selection pressures are at work during speciation? Which pathways accelerate the speed of speciation? Which kinds of trait variabilities makes difficult to find initial split criteria? Elaborating the principles of Fine Structure Analysis (FSA and the morphological Initial Split Criteria (ISP it was discovered that the European spring dwelling caddisfly Potamophylax nigricornis doesn’tbelong to a single species. It represents an entire species group with seventeen peripatric species evolving on the southernperipheries of the distributional area. Four new species subgroups have been erected: Potamophylax nigricornis new species subgroup, P. elegantulus new species subgroup, P. horgos new species subgroup, P. simas new species subgroup. Eleven new species have been described: Potamophylax apados sp. nov., P. fules sp. nov., P. fureses sp. nov., P. hasas sp. novov., P. horgos sp. nov., P. kethas sp. nov., P. lemezes sp. nov., P. peremes sp. nov., P. simas sp. nov., P. tuskes sp. nov., P. ureges sp. nov. One Potamophylax sp. nov. has been differentiated and three new species status have been documented:Potamophylax elegantulus (Klapálek stat. n., P. mista (Navás stat. nov., P. testaceus (Zetterstedt stat. nov.

  20. The Group Objective Structured Clinical Experience: building communication skills in the clinical reasoning context.

    Science.gov (United States)

    Konopasek, Lyuba; Kelly, Kevin V; Bylund, Carma L; Wenderoth, Suzanne; Storey-Johnson, Carol

    2014-07-01

    Students are rarely taught communication skills in the context of clinical reasoning training. The purpose of this project was to combine the teaching of communication skills using SPs with clinical reasoning exercises in a Group Objective Structured Clinical Experience (GOSCE) to study feasibility of the approach, the effect on learners' self-efficacy and attitude toward learning communication skills, and the effect of providing multiple sources of immediate, collaborative feedback. GOSCE sessions were piloted in Pediatrics and Medicine clerkships with students assessing their own performance and receiving formative feedback on communication skills from peers, standardized patients (SPs), and faculty. The sessions were evaluated using a retrospective pre/post-training questionnaire rating changes in self-efficacy and attitudes, and the value of the feedback. Results indicate a positive impact on attitudes toward learning communication skills and self-efficacy regarding communication in the clinical setting. Also, learners considered feedback by peers, SPs, and faculty valuable in each GOSCE. The GOSCE is an efficient and learner-centered method to attend to multiple goals of teaching communication skills, clinical reasoning, self-assessment, and giving feedback in a formative setting. The GOSCE is a low-resource, feasible strategy for experiential learning in communication skills and clinical reasoning. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  1. Atomic resolution structural characterization of recognition of histo-blood group antigens by Norwalk virus

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae-Mun; Hutson, Anne M.; Estes, Mary K.; Prasad, B.V. Venkataram (Baylor)

    2008-07-28

    Members of Norovirus, a genus in the family Caliciviridae, are causative agents of epidemic diarrhea in humans. Susceptibility to several noroviruses is linked to human histo-blood type, and its determinant histo-blood group antigens (HBGAs) are regarded as receptors for these viruses. Specificity for these carbohydrates is strain-dependent. Norwalk virus (NV) is the prototype genogroup I norovirus that specifically recognizes A- and H-type HBGA, in contrast to genogroup II noroviruses that exhibit a more diverse HBGA binding pattern. To understand the structural basis for how HBGAs interact with the NV capsid protein, and how the specificity is achieved, we carried out x-ray crystallographic analysis of the capsid protein domain by itself and in complex with A- and H-type HBGA at a resolution of {approx}1.4 {angstrom}. Despite differences in their carbohydrate sequence and linkage, both HBGAs bind to the same surface-exposed site in the capsid protein and project outward from the capsid surface, substantiating their possible role in initiating cell attachment. Precisely juxtaposed polar side chains that engage the sugar hydroxyls in a cooperative hydrogen bonding and a His/Trp pair involved in a cation-p interaction contribute to selective and specific recognition of A- and H-type HBGAs. This unique binding epitope, confirmed by mutational analysis, is highly conserved, but only in the genogroup I noroviruses, suggesting that a mechanism by which noroviruses infect broader human populations is by evolving different sites with altered HBGA specificities.

  2. Recreation of Small Strains Phenomenon under Pavement Structure and Consequences of Failure to Address It

    Science.gov (United States)

    Fedorowicz, Lidia; Kadela, Marta

    2017-10-01

    This paper describes the small strains phenomenon which occurs in the subgrade under a pavement, a phenomenon documented through in-situ tests and recreated in numerical analyses, which lends a practical engineering aspect to the subject matter. The analyses were preceded by: 1) presentation of the role of constitutive models in structure-subgrade system analysis, 2) reference to methods of modelling in mechanistic procedures and possibility of reliable assessment of criterial values in road structures. These studies were coupled with a description of field tests, which recorded strains in subgrade under a loaded pavement: in zone I directly under the pavement – variable, depending on stiffness of the pavement and the load (about 200÷1000.10-6) and below that, in zone II – ‘stabilised’ (about 1÷5.10-6). In summary, it has been found that the accuracy of numerical analyses of structure-subgrade systems is dependent on the adopted constitutive model of the soil and the numerical calculation area representing the subgrade. Recreation and analysis of the pavement-subgrade system behaviour employed the MCC(OC) critical state model. It was determined that a reliable response of the computational model to the load path used can be obtained with a model that has been previously properly calibrated. The paper justifies the need to carry out further, directed field tests, coupled with numerical analyses employing relevant constitutive models for description of the soil’s performance.

  3. A NOVEL APPROACH TO FIND OPTIMIZED NEUTRON ENERGY GROUP STRUCTURE IN MOX THERMAL LATTICES USING SWARM INTELLIGENCE

    Directory of Open Access Journals (Sweden)

    M. AKBARI

    2013-12-01

    Full Text Available Energy group structure has a significant effect on the results of multigroup transport calculations. It is known that UO2–PUO2 (MOX is a recently developed fuel which consumes recycled plutonium. For such fuel which contains various resonant nuclides, the selection of energy group structure is more crucial comparing to the UO2 fuels. In this paper, in order to improve the accuracy of the integral results in MOX thermal lattices calculated by WIMSD-5B code, a swarm intelligence method is employed to optimize the energy group structure of WIMS library. In this process, the NJOY code system is used to generate the 69 group cross sections of WIMS code for the specified energy structure. In addition, the multiplication factor and spectral indices are compared against the results of continuous energy MCNP-4C code for evaluating the energy group structure. Calculations performed in four different types of H2O moderated UO2–PuO2 (MOX lattices show that the optimized energy structure obtains more accurate results in comparison with the WIMS original structure.

  4. A Novel Approach to Find Optimized Neutron Energy Group Structure in MOX Thermal Lattices Using Swarm Intelligence

    International Nuclear Information System (INIS)

    Akbari, M.; Khoshahval, F.; Minucheha, A.; Zolfaghari, A.

    2013-01-01

    Energy group structure has a significant effect on the results of multigroup transport calculations. It is known that UO 2 -PuO 2 (MOX) is a recently developed fuel which consumes recycled plutonium. For such fuel which contains various resonant nuclides, the selection of energy group structure is more crucial comparing to the UO 2 fuels. In this paper, in order to improve the accuracy of the integral results in MOX thermal lattices calculated by WIMSD-5B code, a swarm intelligence method is employed to optimize the energy group structure of WIMS library. In this process, the NJOY code system is used to generate the 69 group cross sections of WIMS code for the specified energy structure. In addition, the multiplication factor and spectral indices are compared against the results of continuous energy MCNP-4C code for evaluating the energy group structure. Calculations performed in four different types of H 2 O moderated UO 2 -PuO 2 (MOX) lattices show that the optimized energy structure obtains more accurate results in comparison with the WIMS original structure

  5. A Novel Approach to Find Optimized Neutron Energy Group Structure in MOX Thermal Lattices Using Swarm Intelligence

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, M.; Khoshahval, F.; Minucheha, A.; Zolfaghari, A. [Shahid Beheshti Univ., Tehran (Iran, Islamic Republic of)

    2013-12-15

    Energy group structure has a significant effect on the results of multigroup transport calculations. It is known that UO{sub 2}-PuO{sub 2} (MOX) is a recently developed fuel which consumes recycled plutonium. For such fuel which contains various resonant nuclides, the selection of energy group structure is more crucial comparing to the UO{sub 2} fuels. In this paper, in order to improve the accuracy of the integral results in MOX thermal lattices calculated by WIMSD-5B code, a swarm intelligence method is employed to optimize the energy group structure of WIMS library. In this process, the NJOY code system is used to generate the 69 group cross sections of WIMS code for the specified energy structure. In addition, the multiplication factor and spectral indices are compared against the results of continuous energy MCNP-4C code for evaluating the energy group structure. Calculations performed in four different types of H{sub 2}O moderated UO{sub 2}-PuO{sub 2} (MOX) lattices show that the optimized energy structure obtains more accurate results in comparison with the WIMS original structure.

  6. Suppression of superconductivity and structural phase transitions under pressure in tetragonal FeS.

    Science.gov (United States)

    Lai, Xiaofang; Liu, Ying; Lü, Xujie; Zhang, Sijia; Bu, Kejun; Jin, Changqing; Zhang, Hui; Lin, Jianhua; Huang, Fuqiang

    2016-08-08

    Pressure is a powerful tool to study iron-based superconductors. Here, we report systematic high-pressure transport and structural characterizations of the newly discovered superconductor FeS. It is found that superconductor FeS (tetragonal) partly transforms to a hexagonal structure at 0.4 GPa, and then completely transforms to an orthorhombic phase at 7.4 GPa and finally to a monoclinic phase above 9.0 GPa. The superconducting transition temperature of tetragonal FeS was gradually depressed by pressure, different from the case in tetragonal FeSe. With pressure increasing, the S-Fe-S angles only slightly change but the anion height deviates farther from 1.38 Å. This change of anion height, together with the structural instability under pressure, should be closely related to the suppression of superconductivity. We also observed an anomalous metal-semiconductor transition at 6.0 GPa and an unusual increased resistance with further compression above 9.6 GPa. The former can be ascribed to the tetragonal-orthorhombic structural phase transition, and the latter to the electronic structure changes of the high-pressure monoclinic phase. Finally, a phase diagram of tetragonal FeS as functions of pressure and temperature was mapped out for the first time, which will shed new light on understanding of the structure and physics of the superconducting FeS.

  7. Attractor of Beam Equation with Structural Damping under Nonlinear Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Danxia Wang

    2015-01-01

    Full Text Available Simultaneously, considering the viscous effect of material, damping of medium, and rotational inertia, we study a kind of more general Kirchhoff-type extensible beam equation utt-uxxtt+uxxxx-σ(∫0l‍(ux2dxuxx-ϕ(∫0l‍(ux2dxuxxt=q(x, in  [0,L]×R+ with the structural damping and the rotational inertia term. Little attention is paid to the longtime behavior of the beam equation under nonlinear boundary conditions. In this paper, under nonlinear boundary conditions, we prove not only the existence and uniqueness of global solutions by prior estimates combined with some inequality skills, but also the existence of a global attractor by the existence of an absorbing set and asymptotic compactness of corresponding solution semigroup. In addition, the same results also can be proved under the other nonlinear boundary conditions.

  8. Giant panda׳s tooth enamel: Structure, mechanical behavior and toughening mechanisms under indentation.

    Science.gov (United States)

    Weng, Z Y; Liu, Z Q; Ritchie, R O; Jiao, D; Li, D S; Wu, H L; Deng, L H; Zhang, Z F

    2016-12-01

    The giant panda׳s teeth possess remarkable load-bearing capacity and damage resistance for masticating bamboos. In this study, the hierarchical structure and mechanical behavior of the giant panda׳s tooth enamel were investigated under indentation. The effects of loading orientation and location on mechanical properties of the enamel were clarified and the evolution of damage in the enamel under increasing load evaluated. The nature of the damage, both at and beneath the indentation surfaces, and the underlying toughening mechanisms were explored. Indentation cracks invariably were seen to propagate along the internal interfaces, specifically the sheaths between enamel rods, and multiple extrinsic toughening mechanisms, e.g., crack deflection/twisting and uncracked-ligament bridging, were active to shield the tips of cracks from the applied stress. The giant panda׳s tooth enamel is analogous to human enamel in its mechanical properties, yet it has superior hardness and Young׳s modulus but inferior toughness as compared to the bamboo that pandas primarily feed on, highlighting the critical roles of the integration of underlying tissues in the entire tooth and the highly hydrated state of bamboo foods. Our objective is that this study can aid the understanding of the structure-mechanical property relations in the tooth enamel of mammals and further provide some insight on the food habits of the giant pandas. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Group functioning in child care centers: Conceptualization, measurement, and relation with structural characteristics

    NARCIS (Netherlands)

    Aarts, M.C.; Burk, W.J.; Riksen-Walraven, J.M.A.

    2016-01-01

    This article introduces and conceptually underpins an instrument to measure group functioning in child care groups, the Group Functioning Instrument for Child Care (GFI-CC). This instrument was applied in 44 Dutch child care groups (0- to 4-year-olds). The results of this first explorative

  10. Structural stability of the smectite-doped lanthanum under high pressures and high temperatures

    International Nuclear Information System (INIS)

    Stefani, Vicente Fiorini

    2012-01-01

    Smectites are phyllosilicates that have a tetrahedron: octahedron structure ratio of 2:1, with high cation exchange capacity (CEC) in the interlayers. For these and other features, smectites have been used in many parts of the world as secondary barriers with the goal of containing a possible leak of radioactive elements in final disposal facilities for radioactive waste through cation exchange. Our aim in this work is to reach the cation exchange in calcium montmorillonite (smectite dioctahedral) by lanthanum to simulate trivalent radionuclides and to study the stability of this structure under high pressure and high temperature. To achieve high pressure it was used two different technique: DAC (Diamond Anvil Cell), achieving pressures up to 12GPa at room temperature and hydraulic press with a toroidal chamber profile to achieve pressures up to 7,7GPa and temperatures up to 900 degree C. The heating is achieved simultaneously by an electric system coupled in the hydraulic press. The outcomes show that the smectite structure doped with lanthanum remains stable under 12GPa at room temperature and 2.5GPa at 200 degree C. However, above 300 degree C at 2.5GPa the structure becomes a new phase of muscovite-like, rich of La, where it loses its interlayer water and turns out to be irreversible. Furthermore, it is important to point out that the higher temperature the better ordered is the structure and it is still stable under 7.7GPa and 900 degree C. Moreover, after all experiments the structure continues being dioctahedral. The new phase of muscovite-like, rich of La, in contact with a calcium solution remains partially unchanged, whereas the other part returns to the original structure (montmorillonite-Ca). The following analyses were performed: X-ray diffraction (XRD) for evaluating the spatial structure; Fourier transform infrared spectroscopy (FTIR) for getting information about the vibrational modes; scanning electron microscopy with dispersive Xray spectroscopy

  11. An integrated paleomagnetic and diagenetic investigation of the Barnett shale and underlying Ellenburger Group carbonates, Fort Worth Basin, Texas

    Science.gov (United States)

    Dennie, Devin P.

    The Ordovician Ellenburger Group carbonates are extensively karsted and brecciated throughout portions of the western half of the Fort Worth Basin, Texas, where it underlies the Mississippian Barnett Shale gas reservoir and source rock. An integrated geochemical/petrographic, paleomagnetic and rock magnetic study was conducted to better understand the nature and timing of diagenetic events in the unit. Samples from three scribe oriented conventional drill cores of the uppermost Ellenburger Group carbonates were analyzed for their diagenetic and paleomagnetic properties. Thermal demagnetization of samples from both units reveals a low-temperature steeply downward viscous remanent magnetization (VRM) as well as several components that are removed at higher temperatures (200-540°C). The higher temperature components reside in magnetite and are interpreted as chemical remanent magnetizations (CRMs) based on low burial temperatures. The specimen directions are streaked from an easterly and shallow direction to a southerly and shallow direction. The modern VRM was used to orient the CRM data for one of the wells and to test the scribe orienting method. The results confirm that the streak of directions is real. The streak disappears when the directions are grouped by diagenetic facies. Specimens from clasts in the karst breccia facies contain a CRM with easterly declinations and shallow inclinations that fails a conglomerate test and has an Ordovician pole. A mixed dolomite-limestone with shale filled fracture facies contains a pole which falls off of but close to the Late Mississippian-Early Pennsylvanian part of the apparent polar wander path. A group of facies (crystalline dolomite, wavy bedded to argillaceous dolomite, mottled, burrowed dolomite with fine grained breccia facies, and clastic-rich peritidal carbonates) contains a Late Permian-Early Triassic CRM. Dolomites with vug-fill solution-reprecipitation features contain a Late Triassic-Jurassic CRM. The results

  12. Effect of season and breed group on the follicular population and cyclicity of heifers under tropical conditions.

    Science.gov (United States)

    Peralta-Torres, Jorge Alonso; Aké-López, Jesús Ricardo; Centurión-Castro, Fernando Gerardo; Segura-Correa, José C

    2017-01-01

    The aim was to determine the effect of season and breed group on follicular population, and presence and size of CL of heifers under tropical conditions. The seasons were hot-dry (March-June), hot-humid (July-October), and fresh-humid (November-February). Thirty Zebu (Brahman) and 38 F1 (Simmental × Brahman) heifers were used. Five evaluations were made in each season, at intervals of 7 days, to assess ovarian activity by ultrasound. Follicles were classified as small (≤4 mm), middle (4.1-8 mm), and large (≥8.1 mm) sizes, and also the size of CL, when present, was measured. Data were analyzed using analysis of variance and logistic regression procedures. Mean number of small follicles was 11.6 ± 2.3 with no effect of season, breed group, or their interaction (P > 0.05). Mean number of middle follicles was influenced by season and breed group; the highest average was found in the fresh-humid season (4.0 ± 0.2) and in F1 heifers (3.6 ± 0.2; P < 0.05). The highest mean number of large follicles was in the hot-humid season (1.4 ± 0.1; P < 0.05). The highest maximum follicle diameter (MFD) mean was registered in the hot-humid season (1.3 mm; P < 0.05) and the lowest proportion of heifers with CL occurred in fresh-humid season (33.3%; P < 0.05). No effect of season, breed group, and interaction on the maximum diameter of the CL was found. In conclusion, season was a very important source of variation. Heifers in the hot-humid season had the largest follicles and MFD, and better cyclicity.

  13. Structural Irreversibility and Enhanced Brittleness under Fatigue in Zr-Based Amorphous Solids

    Directory of Open Access Journals (Sweden)

    Yiming Qiu

    2012-12-01

    Full Text Available The effect of fatigue on ZrCuAl amorphous metals induced by mechanical cyclic loading is investigated using inelastic neutron scattering and the pair density function analysis of neutron diffraction data. With cooling, the local atomic structure undergoes reorganization under fatigue that is directly related to the number of fatigue cycles. Also under fatigue, suppression in the atomic dynamics is observed as well. A structural restructuring occurs within a 4 Å radius and intensifies with increasing the compression cycles, whereas the vibrational density of states is attenuated as the intensity shifts towards the elastic, zero-energy transfer peak. The combined static and dynamic structural effects are a signature of the microscopic changes brought about by fatigue, and together may be the onset for subsequent behaviors following extended cyclic loading such as fracture. Even after the load is removed, the structural changes described here remain and increase with repeated cyclic loading which is an indication that the lattice deforms even before shear bands are formed.

  14. Structural Integrity Assessment of VVER-1000 RPV under Accidental Cool down Transients

    International Nuclear Information System (INIS)

    Shrivastav, V.; Sen, R.N.; Yadav, R.S.

    2012-01-01

    Corrosion, Fatigue and Irradiation embrittlement are the major degradation mechanisms responsible for ageing of RPV (and its internals) of a Pressurized Water Reactor. While corrosion and fatigue can generate cracks, irradiation damage can lead to brittle fracture initiating from these cracks. Ageing in nuclear power plants needs to be managed so as to ensure that design functions remain available throughout the life of the plant. From safety perspective, this implies that ageing degradation of systems, structures and components important to safety remain within acceptable limits. Reactor Pressure Vessel has been identified as the highest priority key component in plant life management for Pressurized Water Reactors. Therefore special attention is required to ensure its structural integrity during its lifetime. In this paper, structural integrity assessment for typical VVER-1000 RPV is carried out under severe accidental cool down transients using the Finite Element Method. Three different accidental scenarios are postulated and safety of the vessel is conservatively assessed under these transients using the Linear Elastic Fracture Mechanics approach. Transient thermo mechanical stress analysis of the core belt region of the RPV is carried out in presence of postulated cracks and stress intensity factors are calculated and compared with the material fracture toughness to assess the structural integrity of the vessel. The paper also include some parametric analyses to justify the methodology. (author)

  15. Detection of structural damage using novelty detection algorithm under variational environmental and operational conditions

    Science.gov (United States)

    El Mountassir, M.; Yaacoubi, S.; Dahmene, F.

    2015-07-01

    Novelty detection is a widely used algorithm in different fields of study due to its capabilities to recognize any kind of abnormalities in a specific process in order to ensure better working in normal conditions. In the context of Structural Health Monitoring (SHM), this method is utilized as damage detection technique because the presence of defects can be considered as abnormal to the structure. Nevertheless, the performance of such a method could be jeopardized if the structure is operating in harsh environmental and operational conditions (EOCs). In this paper, novelty detection statistical technique is used to investigate the detection of damages under various EOCs. Experiments were conducted with different scenarios: damage sizes and shapes. EOCs effects were simulated by adding stochastic noise to the collected experimental data. Different levels of noise were studied to determine the accuracy and the performance of the proposed method.

  16. Detection of structural damage using novelty detection algorithm under variational environmental and operational conditions

    International Nuclear Information System (INIS)

    Mountassir, M El; Yaacoubi, S; Dahmene, F

    2015-01-01

    Novelty detection is a widely used algorithm in different fields of study due to its capabilities to recognize any kind of abnormalities in a specific process in order to ensure better working in normal conditions. In the context of Structural Health Monitoring (SHM), this method is utilized as damage detection technique because the presence of defects can be considered as abnormal to the structure. Nevertheless, the performance of such a method could be jeopardized if the structure is operating in harsh environmental and operational conditions (EOCs). In this paper, novelty detection statistical technique is used to investigate the detection of damages under various EOCs. Experiments were conducted with different scenarios: damage sizes and shapes. EOCs effects were simulated by adding stochastic noise to the collected experimental data. Different levels of noise were studied to determine the accuracy and the performance of the proposed method. (paper)

  17. Incubation under fluid dynamic conditions markedly improves the structural preservation in vitro of explanted skeletal muscles

    Directory of Open Access Journals (Sweden)

    Flavia Carton

    2017-11-01

    Full Text Available Explanted organs and tissues represent suitable experimental systems mimicking the functional and structural complexity of the living organism, with positive ethical and economic impact on research activities. However, their preservation in culture is generally limited, thus hindering their application as experimental models for biomedical research. In the present study, we investigated the potential of an innovative fluid dynamic culture system to improve the structural preservation in vitro of explanted mouse skeletal muscles (soleus. We used light and transmission electron microscopy to compare the morphological features of muscles maintained either in multiwell plates under conventional conditions or in a bioreactor mimicking the flow of physiological fluids. Our results demonstrate that fluid dynamic conditions markedly slowed the progressive structural deterioration of the muscle tissue occurring during the permanence in the culture medium, prolonging the preservation of some organelles such as mitochondria up to 48 h.

  18. Structural-impurity ordering under the effect of low doses of penetrating radiation

    International Nuclear Information System (INIS)

    Borkovskaya, O.Yu.; Grusha, S.A.; Dmitruk, N.L.

    1985-01-01

    Electrophysical, photoelectrical, electrooptical and metallographic investigations of the effect of radiation-induced ordering in multilayer homoepitaxial structures n + -n-n ++ -GaAs being in contact with metal (Au, Sn, Cr, Pt) are performed. It is established that this effect manifested in the growth of charge carrier mobility and their lifetime owing to weakening of radiationless recombination is clearly prounced in thin near the surface n + -layers and occurs but in imperfect structures with high density of three-dimensional defects (''cupolas''). Experimental features of the radiation-induced ordering effect indicate the structural-impurity transformations in the n + -GaAs near the surface under penetrating radiation. It is assumed that the nature of these transformations consists in the interaction of impurities and primary defects resulting in formation of neutral complexes. The surface effect intensification is explained by planar gettering of defects in the course of which their shifting along the surface occurs

  19. Fatigue degradation and failure of rotating composite structures - Materials characterisation and underlying mechanisms

    DEFF Research Database (Denmark)

    Gamstedt, Kristofer; Andersen, Svend Ib Smidt

    2001-01-01

    The present review concerns rotating composite structures, in which fatigue degradation is of key concern for in-service failure. Such applications are for instance rotor blades in wind turbines, helicopter rotor blades, flywheels for energy storage,marine and aeronautical propellers, and rolls...... for paper machines. The purpose is to identify areas where impending efforts should be made to make better use of composite materials in these applications. In order to obtain better design methodologies,which would allow more reliable and slender structures, improved test methods are necessary. Furthermore......, the relation between structural, component and specimen test results should be better understood than what is presently the case. Improvedpredictive methods rely on a better understanding of the underlying damage mechanisms. With mechanism-based models, the component substructure or even the material...

  20. The numeric visual evaluation of subsoil structure (SubVESS) under agricultural production

    DEFF Research Database (Denmark)

    Ball, B.C.; Batey, Tom; Munkholm, Lars Juhl

    2015-01-01

    Subsoil degradation in agriculture is an increasing problem worldwide, particularly due to compaction caused by heavy machinery. Here, we describe a numeric assessment of subsoil structural quality in relation to soil as a crop growth medium and illustrate its utility with results from compaction...... experiments and from fields under minimum tillage. The scoring scheme resembles the topsoil visual evaluation of soil structure (VESS) (Guimarães et al., 2011) with more emphasis on examination of the profile wall and of soil fragments. The focus is on identification and evaluation of the anthropic...... forest or long-term grassland helped to distinguish whether subsoil structural quality resulted from the natural soil composition or from degradation by land management. The derived scores may be used to judge the requirement for amelioration by subsoil loosening by mechanical inputs (e.g. deep tillage...

  1. Incubation under fluid dynamic conditions markedly improves the structural preservation in vitro of explanted skeletal muscles.

    Science.gov (United States)

    Carton, Flavia; Calderan, Laura; Malatesta, Manuela

    2017-11-28

    Explanted organs and tissues represent suitable experimental systems mimicking the functional and structural complexity of the living organism, with positive ethical and economic impact on research activities. However, their preservation in culture is generally limited, thus hindering their application as experimental models for biomedical research. In the present study, we investigated the potential of an innovative fluid dynamic culture system to improve the structural preservation in vitro of explanted mouse skeletal muscles (soleus). We used light and transmission electron microscopy to compare the morphological features of muscles maintained either in multiwell plates under conventional conditions or in a bioreactor mimicking the flow of physiological fluids. Our results demonstrate that fluid dynamic conditions markedly slowed the progressive structural deterioration of the muscle tissue occurring during the permanence in the culture medium, prolonging the preservation of some organelles such as mitochondria up to 48 h.

  2. STUDY STRUCTURE OF THREE-COMPONENT POLYMERIC MATERIAL UNDER INFLUENCE OF γ-IRRADIATION

    Directory of Open Access Journals (Sweden)

    V. T. Tarasyuk

    2017-01-01

    Full Text Available The polymer material (РА/РЕ/Eva with a width of 55 μm was studied. Sterilization was carried out on the unit GU–200 at doses from 3 to 18 kGy in the Research Institute of Technical Physics and Automation, Rosatom, Moscow, Russia. The structure of the polymermaterial samples was studied by IR spectroscopy before and after irradiation in a range of 400–5000 сm–1. According to the results of the analysis of the IR spectrum structure, the changes in the structure were insignificant upon irradiation at doses up to 6 kGy. Upon irradiation at doses from 9 kGy and higher, an increase in quantity of ester groups (2340 сm–1 and insignificant increase in other functional groups were observed, which can suggest a simultaneous process of intra-molecular cross-linking with the intermediatestage of cross-linking occurring with formation of vinylene groups. This causes destruction of a polymer material and radiation oxidation. These disorders can lead to changes in physico-mechanical and barrier parameters of a polymer material, which can be notably reflected in the shelf life of agricultural products.

  3. Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation

    Science.gov (United States)

    Pentaris, Fragkiskos P.; Fouskitakis, George N.

    2014-05-01

    The problem of modal identification in civil structures is of crucial importance, and thus has been receiving increasing attention in recent years. Vibration-based methods are quite promising as they are capable of identifying the structure's global characteristics, they are relatively easy to implement and they tend to be time effective and less expensive than most alternatives [1]. This paper focuses on the off-line structural/modal identification of civil (concrete) structures subjected to low-level earthquake excitations, under which, they remain within their linear operating regime. Earthquakes and their details are recorded and provided by the seismological network of Crete [2], which 'monitors' the broad region of south Hellenic arc, an active seismic region which functions as a natural laboratory for earthquake engineering of this kind. A sufficient number of seismic events are analyzed in order to reveal the modal characteristics of the structures under study, that consist of the two concrete buildings of the School of Applied Sciences, Technological Education Institute of Crete, located in Chania, Crete, Hellas. Both buildings are equipped with high-sensitivity and accuracy seismographs - providing acceleration measurements - established at the basement (structure's foundation) presently considered as the ground's acceleration (excitation) and at all levels (ground floor, 1st floor, 2nd floor and terrace). Further details regarding the instrumentation setup and data acquisition may be found in [3]. The present study invokes stochastic, both non-parametric (frequency-based) and parametric methods for structural/modal identification (natural frequencies and/or damping ratios). Non-parametric methods include Welch-based spectrum and Frequency response Function (FrF) estimation, while parametric methods, include AutoRegressive (AR), AutoRegressive with eXogeneous input (ARX) and Autoregressive Moving-Average with eXogeneous input (ARMAX) models[4, 5

  4. Vibrational spectroscopy studies of structural changes in lignin under microwave irradiation

    Science.gov (United States)

    Arapova, O. V.; Bondarenko, G. N.; Chistyakov, A. V.; Tsodikov, M. V.

    2017-09-01

    Structural changes that occur in lignin surface-modified with nickel nanoparticles during microwave- assisted dry reforming (DR) are studied via vibrational spectroscopy. IR spectroscopy reveals that the nickel deposition has a considerable effect on the structural characteristics of lignin. It is found that nickel deposition from an acetate salt substantially reduces the intensity of absorption bands at 1700 cm-1. This finding suggests that Ni(2+) interacts mostly with formate groups, which are subsequently oxidized to carboxylate groups. It is shown that with the deposition of metallic nickel particles from a colloidal nickel solution in toluene prepared via metal vapor synthesis, the nickel particles do not interact with the surface functional groups of the lignin. Deep conversion of an organic mass of lignin by DR to form synthesis gas reduces the intensity of the absorption bands of the identified functional groups and raises the intensity of the absorption bands of the aromatic rings. Raman spectroscopy shows that during lignin conversion, the aromatic rings condense partially to form amorphized graphite. In operando studies reveal that the DR of nickel-modified lignin heated to 200-400°C results in the isolation of vanillic oxygenates that are probably intermediate products of reforming.

  5. Development of measurement systems for studies of flow - structure interactions in pipe systems under LWR conditions

    International Nuclear Information System (INIS)

    Kuschewski, Mario; Laurien, Eckart

    2012-01-01

    The Institute for Nuclear Power Studies and Energy Systems (IKE) of the University of Stuttgart is setting up new test rigs for studies of cyclic thermal load phenomena within the 'Studies of Flow-Structure Interactions in Light Water Reactors' joint project. The project is part of a total of three individual projects within an overarching BMBF joint project on reactor safety research, 'Basic Principles of Systems, Discharge and Materials Behavior of Pipes Under Cyclic Thermal Loads.' The article covers the aspect of experimental studies for fluid mechanics modeling of flow-structure interactions. Detailed points under study are thermal mixing processes or laminar flows in a typical tee-shaped pipe branch. The interaction between a fluid and a pipe structure exerts considerable influence on the loads and stresses acting on a component and on the resultant fatigue of a material. In this connection, modeling the mixing process, including effects of buoyancy, thermal conduction and head transfer between the fluid and the wall, is of decisive importance. The experimental data so far accumulated in studies of non-isothermal mixtures cover but a very narrow range of temperatures. The focus of this work is on the development of technical measurement systems for studies of cyclic thermal loads and stresses to be applied to pipe elements specific to LWRs under realistic thermal and flow conditions. On the basis of reliable experimental data, the processes referred to above and their underlying mechanisms can then be examined in the further course of work, and models can be studied for applicability and extended where necessary. (orig.)

  6. Asymmetric flexural behavior from bamboo's functionally graded hierarchical structure: underlying mechanisms.

    Science.gov (United States)

    Habibi, Meisam K; Samaei, Arash T; Gheshlaghi, Behnam; Lu, Jian; Lu, Yang

    2015-04-01

    As one of the most renewable resources on Earth, bamboo has recently attracted increasing interest for its promising applications in sustainable structural purposes. Its superior mechanical properties arising from the unique functionally-graded (FG) hierarchical structure also make bamboo an excellent candidate for bio-mimicking purposes in advanced material design. However, despite its well-documented, impressive mechanical characteristics, the intriguing asymmetry in flexural behavior of bamboo, alongside its underlying mechanisms, has not yet been fully understood. Here, we used multi-scale mechanical characterizations assisted with advanced environmental scanning electron microscopy (ESEM) to investigate the asymmetric flexural responses of natural bamboo (Phyllostachys edulis) strips under different loading configurations, during "elastic bending" and "fracture failure" stages, with their respective deformation mechanisms at microstructural level. Results showed that the gradient distribution of the vascular bundles along the thickness direction is mainly responsible for the exhibited asymmetry, whereas the hierarchical fiber/parenchyma cellular structure plays a critical role in alternating the dominant factors for determining the distinctly different failure mechanisms. A numerical model has been likewise adopted to validate the effective flexural moduli of bamboo strips as a function of their FG parameters, while additional experiments on uniaxial loading of bamboo specimens were performed to assess the tension-compression asymmetry, for further understanding of the microstructure evolution of bamboo's outer and innermost layers under different bending states. This work could provide insights to help the processing of novel bamboo-based composites and enable the bio-inspired design of advanced structural materials with desired flexural behavior. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  7. Group composition and network structure in school classes : a multilevel application of the p* model

    NARCIS (Netherlands)

    Lubbers, Miranda J.

    2003-01-01

    This paper describes the structure of social networks of students within school classes and examines differences in network structure between classes. In order to examine the network structure within school classes, we focused in particular on the principle of homophily, i.e. the tendency that

  8. Structure and viscosity of a transformer oil-based ferrofluid under an external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Rajnak, M., E-mail: rajnak@saske.sk [Institute of Experimental Physics SAS, Watsonova 47, 04001 Košice (Slovakia); Faculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 04200 Košice (Slovakia); Timko, M.; Kopcansky, P.; Paulovicova, K. [Institute of Experimental Physics SAS, Watsonova 47, 04001 Košice (Slovakia); Tothova, J.; Kurimsky, J.; Dolnik, B.; Cimbala, R. [Faculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 04200 Košice (Slovakia); Avdeev, M.V. [Joint Institute for Nuclear Research, Joliot-Curie 6, Moscow region, 141980 Dubna (Russian Federation); Petrenko, V.I. [Joint Institute for Nuclear Research, Joliot-Curie 6, Moscow region, 141980 Dubna (Russian Federation); Taras Shevchenko Kyiv National University, Volodymyrska Street 64, 01601 Kyiv (Ukraine); Feoktystov, A. [Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching (Germany)

    2017-06-01

    Various structural changes of ferrofluids have been intensively studied under external magnetic fields. In this work we present an experimental evidence of similar changes induced by an electric field. In the context of the electric field effect on ferrofluids structure, we studied a simple ferrofluid consisting of iron oxide nanoparticles coated with oleic acid and dispersed in transformer oil. The structural changes have been observed both on macroscopic and microscopic scale. We also demonstrate a remarkable impact of the electric field on the ferrofluid viscosity in relation to the reported structural changes. It was found that the electric field induced viscosity changes are analogous to the magnetoviscous effect. These changes and the electroviscous effect are believed to stem from the dielectric permittivity contrast between the iron oxide nanoparticles and transformer oil, giving rise to the effective electric polarization of the nanoparticles. It is highlighted that this electrorheological effect should be considered in studies of ferrofluids for high voltage engineering applications, as it can have impact on the thermomagnetic convection or the dielectric breakdown performance. - Highlights: • An experimental evidence of the electric field induced structural changes in a ferrofluid is presented. • An electroviscous effect in the transformer oil-based ferrofluid is shown. • The dielectric contrast between the particles and the carrier fluid is the key factor. • The potential impact on the thermomagnetic convection of ferrofluids in power transformers is highlighted.

  9. A stochastic global identification framework for aerospace structures operating under varying flight states

    Science.gov (United States)

    Kopsaftopoulos, Fotis; Nardari, Raphael; Li, Yu-Hung; Chang, Fu-Kuo

    2018-01-01

    In this work, a novel data-based stochastic "global" identification framework is introduced for aerospace structures operating under varying flight states and uncertainty. In this context, the term "global" refers to the identification of a model that is capable of representing the structure under any admissible flight state based on data recorded from a sample of these states. The proposed framework is based on stochastic time-series models for representing the structural dynamics and aeroelastic response under multiple flight states, with each state characterized by several variables, such as the airspeed, angle of attack, altitude and temperature, forming a flight state vector. The method's cornerstone lies in the new class of Vector-dependent Functionally Pooled (VFP) models which allow the explicit analytical inclusion of the flight state vector into the model parameters and, hence, system dynamics. This is achieved via the use of functional data pooling techniques for optimally treating - as a single entity - the data records corresponding to the various flight states. In this proof-of-concept study the flight state vector is defined by two variables, namely the airspeed and angle of attack of the vehicle. The experimental evaluation and assessment is based on a prototype bio-inspired self-sensing composite wing that is subjected to a series of wind tunnel experiments under multiple flight states. Distributed micro-sensors in the form of stretchable sensor networks are embedded in the composite layup of the wing in order to provide the sensing capabilities. Experimental data collected from piezoelectric sensors are employed for the identification of a stochastic global VFP model via appropriate parameter estimation and model structure selection methods. The estimated VFP model parameters constitute two-dimensional functions of the flight state vector defined by the airspeed and angle of attack. The identified model is able to successfully represent the wing

  10. The Comparison of Dentine Thickness Under Proximal Caries Between Bitewing Radiographs and Tooth Structure

    Directory of Open Access Journals (Sweden)

    Khosravi K

    2001-05-01

    Full Text Available Carious lesions are usually found by dentists, using bitewing radiographs, and according to the depth of the lesions, the treatment plan is designed. At the present, this technique is the most accepted one and is used generally. But it is not a perfect technique and there are some errors in determining of depth of proximal carious lesions. These errors are mainly related to the use of new high-speed films with broad density and lower voltages. In this study, dentin thickness under proximal caries in bitewing radiography was compared with its real thickness, in tooth structure. Twenty-four teeth samples with proximal caries were used. Before and after removal of carious lesions bitewing radiographs were taken and then each tooth was sectioned occlusogingivally and the thickness of dentine under proximal caries and on bitewing radiographs were measured under microscope with 0.01 mm accuracy. Mean value of dentine thickness in tooth structure was 41% of its mean thickness in bitewing radiographs, showing 59% difference (reduction. Therefore, more care should be taken in using standard technique and interpreting of bitewing radiographs by clinicians. Clinical examinations also should be performed in ideal conditions, and patients should be clinically and radiographically examined every six months.

  11. Surface (glyco-)proteins: primary structure and crystallization under microgravity conditions

    Science.gov (United States)

    Claus, H.; Akca, E.; Schultz, N.; Karbach, G.; Schlott, B.; Debaerdemaeker, T.; De Clercq, J.-P.; König, H.

    2001-08-01

    The Archaea comprise microorganisms that live under environmental extremes, like high temperature, low pH value or high salt concentration. Their cells are often covered by a single layer of (glyco)protein subunits (S-layer) in hexagonal arrangement. In order to get further hints about the molecular mechanisms of protein stabilization we compared the primary and secondary structures of archaeal S-layer (glyco)proteins. We found an increase of charged amino acids in the S-layer proteins of the extreme thermophilic species compared to their mesophilic counterparts. Our data and those of other authors suggest that ionic interactions, e.g., salt bridges seem to be played a major role in protein stabilization at high temperatures. Despite the differences in the growth optima and the predominance of some amino acids the primary structures of S-layers revealed also a significant degree of identity between phylogenetically related archaea. These obervations indicate that protein sequences of S-layers have been conserved during the evolution from extremely thermophilic to mesophilic life. To support these findings the three-dimensional structure of the S-layer proteins has to be elucidated. Recently, we described the first successful crystallization of an extreme thermophilic surface(glyco)protein under microgravity conditions.

  12. Concrete Mix Design for Service Life of RC Structures under Carbonation Using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Seung-Jun Kwon

    2014-01-01

    Full Text Available Steel corrosion in reinforced concrete (RC structure is such a critical problem to structural safety that many researches have been performed for maintaining required performance during intended service life. This paper is for a numerical technique for obtaining optimum concrete mix proportions through genetic algorithm (GA for RC structures under carbonation which is considered as a serious deterioration in underground sites and big cities. For this study, mix proportions and CO2 diffusion coefficients are analyzed through the previous studies, and then the fitness function of CO2 diffusion coefficient is derived through regression analysis. The fitness function from 69 test results includes 5 variables of mix proportions such as w/c (water to cement ratio, cement content, sand content percentage, coarse aggregate content, and R.H. (relative humidity. Through GA technique, simulated mix proportions are obtained for 12 cases of verification and they show reasonable results with average relative error of 4.6%. Assuming intended service life and design parameters, intended CO2 diffusion coefficients and cement contents are determined and then related mix proportions are simulated. The proposed technique can provide initial concrete mix proportions which satisfy service life under carbonation.

  13. Structural Statics and Dynamics of the Economy of Transcarpathia under Pre-Crisis and Crisis Conditions

    Directory of Open Access Journals (Sweden)

    Slava Svitlana S.

    2015-03-01

    Full Text Available Under current conditions in Ukraine, when the vector is directed at increasing self-sufficiency of the regions, diagnostics of structural transformations in their economic systems is a mandatory and necessary component to identify potential points of the region development. Accordingly, the purpose of the article is to study the structural trends in the economy of the Transcarpathian region and identify its leading sectors under the pre-crisis and crisis conditions, balance in dynamics of the main indicators — the volume of sales, regional value added, capital investment and the number of employees, as well as formation of the main directions in development of the regional economy. It has been revealed that for the past ten years the restructuring of the region economic did not go on too rapidly and it is still difficult to speak about a clear trend of transition to a post-industrial system. Given the current characteristics of the economy of Transcarpathia, the article defined the basic problematic aspects of its structural transformation. It allowed to determine the long-term, according to the authors, ways of “modernization” of economic processes in terms of attracting investments, increasing innovation, business activity, formation of a complete production cycle, use of alternative energy sources, implementation of the EU requirements.

  14. Measurement of deforming mode of lattice truss structures under impact loading

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    Zhao H.

    2012-08-01

    Full Text Available Lattice truss structures, which are used as a core material in sandwich panels, were widely investigated experimentally and theoretically. However, explanation of the deforming mechanism using reliable experimental results is almost rarely reported, particularly for the dynamic deforming mechanism. The present work aimed at the measurement of the deforming mode of lattice truss structures. Indeed, quasi-static and Split Hopkinson Pressure Bar (SHPB tests have been performed on the tetrahedral truss cores structures made of Aluminum 3003-O. Global values such as crushing forces and displacements between the loading platens are obtained. However, in order to understand the deforming mechanism and to explain the observed impact strength enhancement observed in the experiments, images of the truss core element during the tests are recorded. A method based on the edge detection algorithm is developed and applied to these images. The deforming profiles of one beam are extracted and it allows for calculating the length of beam. It is found that these lengths diminish to a critical value (due to compression and remain constant afterwards (because of significant bending. The comparison between quasi-static and impact tests shows that the beam were much more compressed under impact loading, which could be understood as the lateral inertia effect in dynamic bucking. Therefore, the impact strength enhancement of tetrahedral truss core sandwich panel can be explained by the delayed buckling of beam under impact (more compression reached, together with the strain hardening of base material.

  15. Application of the Recursive Finite Element Approach on 2D Periodic Structures under Harmonic Vibrations

    Directory of Open Access Journals (Sweden)

    Reem Yassine

    2016-12-01

    Full Text Available The frequency response function is a quantitative measure used in structural analysis and engineering design; hence, it is targeted for accuracy. For a large structure, a high number of substructures, also called cells, must be considered, which will lead to a high amount of computational time. In this paper, the recursive method, a finite element method, is used for computing the frequency response function, independent of the number of cells with much lesser time costs. The fundamental principle is eliminating the internal degrees of freedom that are at the interface between a cell and its succeeding one. The method is applied solely for free (no load nodes. Based on the boundary and interior degrees of freedom, the global dynamic stiffness matrix is computed by means of products and inverses resulting with a dimension the same as that for one cell. The recursive method is demonstrated on periodic structures (cranes and buildings under harmonic vibrations. The method yielded a satisfying time decrease with a maximum time ratio of 1 18 and a percentage difference of 19%, in comparison with the conventional finite element method. Close values were attained at low and very high frequencies; the analysis is supported for two types of materials (steel and plastic. The method maintained its efficiency with a high number of forces, excluding the case when all of the nodes are under loads.

  16. Environmental Effects on Long Term Displacement Data of Woven Fabric Webbings Under Constant Load for Inflatable Structures

    Science.gov (United States)

    Kenner, WInfred S.; Jones, Thomas C.; Doggett, William R.; Duncan, Quinton; Plant, James

    2015-01-01

    An experimental study of the effects of environmental temperature and humidity conditions on long-term creep displacement data of high strength Kevlar and VectranTM woven fabric webbings under constant load for inflatable structures is presented. The restraint layer of an inflatable structure for long-duration space exploration missions is designed to bear load and consists of an assembly of high strength webbings. Long-term creep displacement data of webbings can be utilized by designers to validate service life parameters of restraint layers of inflatable structures. Five groups of high-strength webbings were researched over a two year period. Each group had a unique webbing length, load rating, applied load, and test period. The five groups consisted of 1.) 6K Vectran webbings loaded to 49% ultimate tensile strength (UTS), 2.) 6K Vectran webbings loaded to 55% UTS, 3.) 12.5K Vectran webbings loaded to 22% UTS, 4.) 6K Kevlar webbings loaded to 40% and 43% UTS, and 5.) 6K Kevlar webbings loaded to 48% UTS. Results show that all webbing groups exhibit the initial two stages of three of a typical creep curve of an elastic material. Results also show that webbings exhibit unique local wave patterns over the duration of the test period. Data indicate that the local pattern is primarily generated by daily variations in relative humidity values within the test facility. Data indicate that after a three to six month period, where webbings reach a steady-state creep condition, an annual sinusoidal displacement pattern is exhibited, primarily due to variations in annual mean temperature values. Data indicates that variations in daily temperature values and annual mean humidity values have limited secondary effects on creep displacement behavior. Results show that webbings in groups 2 and 5 do not exhibit well defined annual displacement patterns because the magnitude of the applied loads cause large deformations, and data indicate that material yielding within a webbing

  17. Crystal Structure of a Group I Energy Coupling Factor Vitamin Transporter S Component in Complex with Its Cognate Substrate.

    Science.gov (United States)

    Josts, Inokentijs; Almeida Hernandez, Yasser; Andreeva, Antonina; Tidow, Henning

    2016-07-21

    Energy coupling factor (ECF) transporters are responsible for the uptake of essential scarce nutrients in prokaryotes. This ATP-binding cassette transporter family comprises two subgroups that share a common architecture forming a tripartite membrane protein complex consisting of a translocation component and ATP hydrolyzing module and a substrate-capture (S) component. Here, we present the crystal structure of YkoE from Bacillus subtilis, the S component of the previously uncharacterized group I ECF transporter YkoEDC. Structural and biochemical analyses revealed the constituent residues of the thiamine-binding pocket as well as an unexpected mode of vitamin recognition. In addition, our experimental and bioinformatics data demonstrate major differences between YkoE and group II ECF transporters and indicate how group I vitamin transporter S components have diverged from other group I and group II ECF transporters. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Long Term Displacement Data of Woven Fabric Webbings Under Constant Load for Inflatable Structures

    Science.gov (United States)

    Kenner, Winfred S.; Jones, Thomas C.; Doggett, William R.; Lucy, Melvin H.; Grondin, Trevor A.; Whitley, Karen S.; Duncan, Quinton; Plant, James V.

    2014-01-01

    Inflatable modules for space applications offer weight and launch volume savings relative to current metallic modules. Limited data exist on the creep behavior of the restraint layer of inflatable modules. Long-term displacement and strain data of two high strength woven fabric webbings, Kevlar and Vectran, under constant load is presented. The creep behavior of webbings is required by designers to help determine service life parameters of inflatable modules. Four groups of different webbings with different loads were defined for this study. Group 1 consisted of 4K Kevlar webbings loaded to 33% ultimate tensile strength and 6K Vectran webbings loaded to 27% ultimate tensile strength, group 2 consisted of 6K Kevlar webbings loaded to 40% and 43% ultimate tensile strength, and 6K Vectran webbings loaded to 50% ultimate tensile strength, group 3 consisted of 6K Kevlar webbings loaded to 52% ultimate tensile strength and 6K Vectran webbings loaded to 60% ultimate tensile strength, and group 4 consisted of 12.5K Kevlar webbings loaded to 22% ultimate tensile strength, and 12.5K Vectran webbings loaded to 22% ultimate tensile strength. The uniquely designed test facility, hardware, displacement measuring devices, and test data are presented. Test data indicate that immediately after loading all webbings stretch an inch or more, however as time increases displacement values significantly decrease to fall within a range of several hundredth of an inch over the remainder of test period. Webbings in group 1 exhibit near constant displacements and strains over a 17-month period. Data acquisition was suspended after the 17th month, however webbings continue to sustain load without any local webbing damage as of the 21st month of testing. Webbings in group 2 exhibit a combination of initial constant displacement and subsequent increases in displacement rates over a 16-month period. Webbings in group 3 exhibit steady increases in displacement rates leading to webbing failure

  19. Influence of landscape structure on the functional groups of an aphidophagous guild: Active-searching predators, furtive predators and parasitoids

    Directory of Open Access Journals (Sweden)

    Julie-Éléonore Maisonhaute

    2011-12-01

    Full Text Available A lot of studies focusing on the effect of agricultural landscapes demonstrate that many arthropod species are influenced by landscape structure. In particular, non–crop areas and landscape diversity are often associated with a higher abundance and diversity of natural enemies in fields. Numerous studies focused on the influence of landscape structure on ground beetles, spiders and ladybeetles but few on other natural enemies or different functional groups. Thus, the objective of the present study was to determine the influence of landscape structure on the functional groups, i.e., active-searching predators, furtive predators and parasitoids of aphidophagous guilds. Natural enemies were sampled on milkweed infested with aphids, growing along the borders of ditches adjacent to cornfields. The sampling occurred weekly from June to September in 2006 and 2007, in the region of Lanaudičre (Quebec, Canada. The landscapes within a radius 200 and 500 m around each site were analyzed. The abundance, richness and species composition (based on functional groups of natural enemies were related to landscape structure. The results indicated that landscape structure explained up to 21.6% of the variation in natural enemy assemblage and confirm the positive effects of non-crop areas and landscape diversity. A lower influence of landscape structure on species composition was observed (6.4 to 8.8% and varied greatly among the functional groups. Coccinellidae and furtive predators were the group most influenced by landscape structure. In conclusion, the influence of landscape varied greatly among the different species of the same functional group.

  20. Electron spin transition causing structure transformations of earth's interiors under high pressure

    Science.gov (United States)

    Yamanaka, T.; Kyono, A.; Kharlamova, S.; Alp, E.; Bi, W.; Mao, H.

    2012-12-01

    To elucidate the correlation between structure transitions and spin state is one of the crucial problems for understanding the geophysical properties of earth interiors under high pressure. High-pressure studies of iron bearing spinels attract extensive attention in order to understand strong electronic correlation such as the charge transfer, electron hopping, electron high-low spin transition, Jahn-Teller distortion and charge disproponation in the lower mantle or subduction zone [1]. Experiment Structure transitions of Fe3-xSixO4, Fe3-xTixO4 Fe3-xCrxO4 spinel solid solution have been investigated at high pressure up to 60 GPa by single crystal and powder diffraction studies using synchrotron radiation with diamond anvil cell. X-ray emission experiment (XES) at high pressure proved the spin transition of Fe-Kβ from high spin (HS) to intermediate spin state (IS) or low spin state (LS). Mössbauer experiment and Raman spectra study have been also conducted for deformation analysis of Fe site and confirmation of the configuration change of Fe atoms. Jahn-Teller effect A cubic-to-tetragonal transition under pressure was induced by Jahn-Teller effect of IVFe2+ (3d6) in the tetrahedral site of Fe2TiO4 and FeCr2O4, providing the transformation from 43m (Td) to 42m (D2d). Tetragonal phase is formed by the degeneracy of e orbital of Fe2+ ion. Their c/a ratios are c/adisordered in the M2 site. At pressures above 53 GPa, Fe2TiO4 structure further transforms to Pmma. This structure change results in the order-disorder transition [2]. New structure of Fe2SiO4 The spin transition exerts an influence to Fe2SiO4 spinel structure and triggers two distinct curves of the lattice constant in the spinel phase. The reversible structure transition from cubic to pseudo-rhombohedral phase was observed at about 45 GPa. This transition is induced by the 20% shrinkage of ionic radius of VIFe2+at the low sin state. Laser heating experiment at 1500 K has confirmed the decomposition from the

  1. Structural distortions in 5-10 nm silver nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Koski, Kristie J.; Kamp, Noelle M.; Kunz, Martin; Knight, Jason K.; Alivisatos, A.P.; Smith, R.K.

    2008-10-13

    We present experimental evidence that silver nanoparticles in the size range of 5-10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. We have used x-ray diffraction with a synchrotron light source to investigate pressure-dependent and size-dependent trends in the crystal structure of silver nanoparticles in a hydrostatic medium compressed in a diamond-anvil cell. Results suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. We propose a mechanism for this transition that considers the bond-length distribution in idealized multiply twinned icosahedral particles. To further support this hypothesis, we also show that similar measurements of single-crystal platinum nanoparticles reveal no such distortions.

  2. Evaluation of Reinforced Concrete Structural Members under Uniform Loads Using Truss Model

    Directory of Open Access Journals (Sweden)

    Houshang Dabbagh

    2016-03-01

    Full Text Available Truss model is an analytical approach to predict the strength of reinforced concrete members with geometric or statical discontinuous regions. This study investigates the use of truss model to predict the structural behavior of reinforced concrete members with discontinuity areas under monotonic loading. The estimated failure load and its corresponding deformation are the main objective of this research. Twenty and three samples including short shear walls, short columns and deep beams tested by other researchers throughout the literature have been selected. Then their truss models as well as their three dimensional finite element models are analyzed using ABAQUS software. The comparison of experimental and analytical results shows fair correlation between them. Also, the structural response of samples estimated by truss model analysis is fairly acceptable.

  3. Underlying Predictors of Tobacco Smoking among Iranian Teenagers: Generalized Structural Equation Modeling

    Directory of Open Access Journals (Sweden)

    Fariba Khayyati

    2016-09-01

    Full Text Available Background: To define underlying predictors of tobacco smoking among Iranian Teenagers in a generalized structural equation model. Materials and Methods: In this cross-sectional study, a Generalized Structural Equation Model based on planned behavioral theory was used to explain the relationship among different factors such as demographic factors, subjective norms, and the intention to tobacco and, in turn, intention with tobacco use. The sample consisted of 4,422 high school students, based on census, in East Azerbaijan province, Iran. The questioner was designed adapting to the objectives of study. It was used global youth tobacco survey to design the queries of tobacco use. Results: The model had a good fit on data. Adjusting for age and gender, there was a statistically significant relationship between the intention to consumption and the following factors: working while studying (P

  4. Topological Control on the Structural Relaxation of Atomic Networks under Stress

    Science.gov (United States)

    Bauchy, Mathieu; Wang, Mengyi; Yu, Yingtian; Wang, Bu; Krishnan, N. M. Anoop; Masoero, Enrico; Ulm, Franz-Joseph; Pellenq, Roland

    2017-07-01

    Upon loading, atomic networks can feature delayed irreversible relaxation. However, the effect of composition and structure on relaxation remains poorly understood. Herein, relying on accelerated molecular dynamics simulations and topological constraint theory, we investigate the relationship between atomic topology and stress-induced structural relaxation, by taking the example of creep deformations in calcium silicate hydrates (C - S - H ), the binding phase of concrete. Under constant shear stress, C - S - H is found to feature delayed logarithmic shear deformations. We demonstrate that the propensity for relaxation is minimum for isostatic atomic networks, which are characterized by the simultaneous absence of floppy internal modes of relaxation and eigenstress. This suggests that topological nanoengineering could lead to the discovery of nonaging materials.

  5. Study of CRFP Shell Structures under Dynamic Loading in Shock Tube Setup

    Directory of Open Access Journals (Sweden)

    H. A. Khawaja

    2014-01-01

    Full Text Available The paper gives the study of the response of carbon fiber reinforced polymers (CRFP quasi-isotropic shell structures under the influence of dynamic loading. The quasi-isotropic CRFP shell specimens are fabricated using Multipreg E720 laminates. These laminates are laid in such a way that shell structure has equal strength and mechanical properties in the two-dimensional (2D plane and hence can be regarded as quasi-isotropic. In this study, the dynamic loading is generated using shock waves in a shock tube experimental setup. The strain and pressure data is collected from the experiments. Additional tests are carried out using Material Test System (MTS for both tensile and flexural response of CRFP. Results obtained from experiments are compared with numerical simulations using ANSYS Multiphysics 14.0 finite element method (FEM package. The numerical simulation and experimental results are found to be in good agreement.

  6. 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.

  7. Single- and multi-pulse formation of surface structures under static femtosecond irradiation

    Science.gov (United States)

    Guillermin, M.; Garrelie, F.; Sanner, N.; Audouard, E.; Soder, H.

    2007-07-01

    Femtosecond surface structure modifications are investigated under irradiation with laser pulses of 150 fs at 800 nm, on copper and silicon. We report sub-wavelength periodic structures formation (ripples) with a periodicity of 500 nm for both materials. These ripples are perpendicular to the laser polarization and can be obtained with only one pulse. The formation of these ripples corresponds to a fluence threshold of 1 J/cm 2 for copper and 0.15 J/cm 2 for silicon. We find several morphologies when more pulses are applied: larger ripples parallel to the polarization are formed with a periodicity of 1 μm and degenerate into a worm-like morphology with a higher number of pulses. In addition, walls of deep holes also show sub-wavelength and large ripples.

  8. Go East: Differences between Poland and Western European countries in the motivational structures underlying seafood consumption

    DEFF Research Database (Denmark)

    Scholderer, Joachim; Brunsø, Karen; Olsen, Svein Ottar

    Central Europe is an emerging market for seafood products, with rapidly developing opportunities for foreign direct investment and export. Although Poland in particular is widely regarded as a land of opportunity in the seafood business, surprisingly little effort has been made until now to gain...... and compared in terms of the motivational structures underlying seafood consumption. In Poland, intentions to consume seafood in the near future were mainly determined by the perceived difficulty of preparing fish dishes (problems with bone handling and smells) and the degree to which consumers believed...... they had the necessary cooking skills. The preferences of consumers and their household members had a much weaker but still significant impact on intentions. In the comparison samples from Western Europe, motivational structures varied considerably. The highest degree of similarity with Poland was found...

  9. Effects of Home Energy Management Systems on Distribution Utilities and Feeders Under Various Market Structures: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, Mark; Pratt, Annabelle; Lunacek, Monte; Mittal, Saurabh; Wu, Hongyu; Jones, Wesley

    2015-07-17

    The combination of distributed energy resources (DER) and retail tariff structures to provide benefits to both utility consumers and the utilities is poorly understood. To improve understanding, an Integrated Energy System Model (IESM) is being developed to simulate the physical and economic aspects of DER technologies, the buildings where they reside, and feeders servicing them. The IESM was used to simulate 20 houses with home energy management systems on a single feeder under a time of use tariff to estimate economic and physical impacts on both the households and the distribution utilities. HEMS reduce consumers’ electric bills by precooling houses in the hours before peak electricity pricing. Household savings are greater than the reduction utility net revenue indicating that HEMS can provide a societal benefit providing tariffs are structured so that utilities remain solvent. Utilization of HEMS reduce peak loads during high price hours but shifts it to hours with off-peak and shoulder prices and resulting in a higher peak load.

  10. Effect of soft denture liner on stress distribution in supporting structures under a denture.

    Science.gov (United States)

    Kawano, F; Koran, A; Asaoka, K; Matsumoto, N

    1993-01-01

    This study examined the effect of a soft denture liner on the distribution of stresses in the denture-supporting structures. Dentures without a linear and with three configurations of a soft liner were simulated by using a two-dimensional viscoelastic finite-element stress analysis. The stress intensity at functional force-bearing areas decreased when a soft denture liner was used. However, the stresses in the bone increased remarkably up to 3.0 seconds after loading. Because of the time-dependent effect of stresses applied to soft denture liners, denture patients who clench or brux may not benefit as greatly from soft denture liners. The study indicates that viscoelastic finite-element analysis is helpful for evaluating soft denture liners. Soft denture liners appear to be useful for improving the stress distribution in the supporting structures under dentures.

  11. Structural, Mechanical and Thermodynamic Properties under Pressure Effect of Rubidium Telluride: First Principle Calculations

    Directory of Open Access Journals (Sweden)

    Bidai K.

    2017-06-01

    Full Text Available First-principles density functional theory calculations have been performed to investigate the structural, elastic and thermodynamic properties of rubidium telluride in cubic anti-fluorite (anti-CaF2-type structure. The calculated ground-state properties of Rb2Te compound such as equilibrium lattice parameter and bulk moduli are investigated by generalized gradient approximation (GGA-PBE that are based on the optimization of total energy. The elastic constants, Young’s and shear modulus, Poisson ratio, have also been calculated. Our results are in reasonable agreement with the available theoretical and experimental data. The pressure dependence of elastic constant and thermodynamic quantities under high pressure are also calculated and discussed.

  12. Nonlinear Dynamic Analysis of Telescopic Mechanism for Truss Structure Bridge Inspection Vehicle Under Pedestrian Excitation

    Directory of Open Access Journals (Sweden)

    Wenwen Sui

    Full Text Available Abstract Nonlinear dynamic analysis of an axially moving telescopic mechanism for truss structure bridge inspection vehicle under pedestrian excitation is carried out. A biomechanically inspired inverted-pendulum model is utilized to simplify the pedestrian. The nonlinear equations of motion for the beam-pedestrian system are derived using the Hamilton's principle. The equations are transformed into two ordinary differential equations by applying the Galerkin's method at the first two orders. The solutions to the equations are acquired by using the Newmark-β method associated with the Newton-Raphson method. The time-dependent feature of the eigenfunctions for the two beams are taken into consideration in the solutions. Accordingly, the equations of motion for a simplified system, in which the pedestrian is regarded as moving cart, are given. In the numerical examples, dynamic responses of the telescopic mechanism in eight conditions of different beam-telescoping and pedestrian-moving directions are simulated. Comparisons between the vibrations of the beams under pedestrian excitation and corresponding moving cart are carried out to investigate the influence of the pedestrian excitation on the telescopic mechanism. The results show that the displacement of the telescopic mechanism under pedestrian excitation is smaller than that under moving cart especially when the pedestrian approaches the beams end. Additionally, compared with moving cart, the pedestrian excitation can effectively strengthen the vibration when the beam extension is small or when the pedestrian is close to the beams end.

  13. Dynamic Pricing in Cloud Manufacturing Systems under Combined Effects of Consumer Structure, Negotiation, and Demand

    Directory of Open Access Journals (Sweden)

    Wei Peng

    2017-01-01

    Full Text Available In this study, we proposed a game-theory based framework to model the dynamic pricing process in the cloud manufacturing (CMfg system. We considered a service provider (SP, a broker agent (BA, and a dynamic service demander (SD population that is composed of price takers and bargainers in this study. The pricing processes under linear demand and constant elasticity demand were modeled, respectively. The combined effects of SD population structure, negotiation, and demand forms on the SP’s and the BA’s equilibrium prices and expected revenues were examined. We found that the SP’s optimal wholesale price, the BA’s optimal reservation price, and posted price all increase with the proportion of price takers under linear demand but decrease with it under constant elasticity demand. We also found that the BA’s optimal reservation price increases with bargainers’ power no matter under what kind of demand. Through analyzing the participants’ revenues, we showed that a dynamic SD population with a high ratio of price takers would benefit the SP and the BA.

  14. Temperate mountain forest biodiversity under climate change: compensating negative effects by increasing structural complexity.

    Science.gov (United States)

    Braunisch, Veronika; Coppes, Joy; Arlettaz, Raphaël; Suchant, Rudi; Zellweger, Florian; Bollmann, Kurt

    2014-01-01

    Species adapted to cold-climatic mountain environments are expected to face a high risk of range contractions, if not local extinctions under climate change. Yet, the populations of many endothermic species may not be primarily affected by physiological constraints, but indirectly by climate-induced changes of habitat characteristics. In mountain forests, where vertebrate species largely depend on vegetation composition and structure, deteriorating habitat suitability may thus be mitigated or even compensated by habitat management aiming at compositional and structural enhancement. We tested this possibility using four cold-adapted bird species with complementary habitat requirements as model organisms. Based on species data and environmental information collected in 300 1-km2 grid cells distributed across four mountain ranges in central Europe, we investigated (1) how species' occurrence is explained by climate, landscape, and vegetation, (2) to what extent climate change and climate-induced vegetation changes will affect habitat suitability, and (3) whether these changes could be compensated by adaptive habitat management. Species presence was modelled as a function of climate, landscape and vegetation variables under current climate; moreover, vegetation-climate relationships were assessed. The models were extrapolated to the climatic conditions of 2050, assuming the moderate IPCC-scenario A1B, and changes in species' occurrence probability were quantified. Finally, we assessed the maximum increase in occurrence probability that could be achieved by modifying one or multiple vegetation variables under altered climate conditions. Climate variables contributed significantly to explaining species occurrence, and expected climatic changes, as well as climate-induced vegetation trends, decreased the occurrence probability of all four species, particularly at the low-altitudinal margins of their distribution. These effects could be partly compensated by modifying

  15. Temperate mountain forest biodiversity under climate change: compensating negative effects by increasing structural complexity.

    Directory of Open Access Journals (Sweden)

    Veronika Braunisch

    Full Text Available Species adapted to cold-climatic mountain environments are expected to face a high risk of range contractions, if not local extinctions under climate change. Yet, the populations of many endothermic species may not be primarily affected by physiological constraints, but indirectly by climate-induced changes of habitat characteristics. In mountain forests, where vertebrate species largely depend on vegetation composition and structure, deteriorating habitat suitability may thus be mitigated or even compensated by habitat management aiming at compositional and structural enhancement. We tested this possibility using four cold-adapted bird species with complementary habitat requirements as model organisms. Based on species data and environmental information collected in 300 1-km2 grid cells distributed across four mountain ranges in central Europe, we investigated (1 how species' occurrence is explained by climate, landscape, and vegetation, (2 to what extent climate change and climate-induced vegetation changes will affect habitat suitability, and (3 whether these changes could be compensated by adaptive habitat management. Species presence was modelled as a function of climate, landscape and vegetation variables under current climate; moreover, vegetation-climate relationships were assessed. The models were extrapolated to the climatic conditions of 2050, assuming the moderate IPCC-scenario A1B, and changes in species' occurrence probability were quantified. Finally, we assessed the maximum increase in occurrence probability that could be achieved by modifying one or multiple vegetation variables under altered climate conditions. Climate variables contributed significantly to explaining species occurrence, and expected climatic changes, as well as climate-induced vegetation trends, decreased the occurrence probability of all four species, particularly at the low-altitudinal margins of their distribution. These effects could be partly compensated

  16. AFLPs reveal different population genetic structure under contrasting environments in the marine snail Nucella lapillus L.

    Directory of Open Access Journals (Sweden)

    Belén Carro

    Full Text Available Dispersal has received growing attention in marine ecology, particularly since evidence obtained with up-to-date techniques challenged the traditional view. The dogwhelk Nucella lapillus L., a sedentary gastropod with direct development, is a good example: dispersal was traditionally assumed to be limited until studies with microsatellites disputed this idea. To shed some light on this controversy, the genetic structure of dogwhelk populations in northwest Spain was investigated with highly polymorphic AFLP markers giving special attention to the influence of hydrodynamic stress. In agreement with the expectations for a poor disperser, our results show a significant genetic structure at regional (<200 km and areal scales (<15 km. However, the spatial genetic structure varied with wave-exposure in the present case study: IBD was evident under sheltered conditions but absent from the exposed area where genetic differentiation was stronger. Our results provide evidence that differences in wave-exposure can exert a detectable influence on the genetic structure of coastal organisms, even in species without a planktonic larva.

  17. Structural response of cargo containment systems in LNG carriers under ice loads

    International Nuclear Information System (INIS)

    Wang, B.; Yu, H.; Basu, R.; Lee, H.; Kwon, J.C.; Jeon, B.Y.; Kim, J.H.; Daley, C.; Kendrick, A.

    2008-01-01

    Gas exploration has been extended into the Arctic region such as in the Russian Arctic area, because of the increasing demand for energy resources. As a result, shipping in ice-covered seas is also increasing. Many technical issues are involved in ensuring the safety of liquefied natural gas (LNG) ships during the transportation. This paper discussed an investigation of ship-ice interaction scenarios for possible operation routes in Arctic areas. Six scenarios were selected to study the structural response of cargo containment systems (CCS) in both membrane and spherical types of LNG ships. For selected ship-ice interaction scenarios, ice loads and loading areas in the hull structure were determined based on the energy theory. The configurations of LNG carriers were discussed and illustrated. The paper also outlined the assessment criteria and structure analysis procedures. It was concluded that the strength of the CCS of membrane-type LNG carrier and the strength of the skirt structure of spherical-type LNG carrier were strong enough under the design ice loads. 13 refs., 9 tabs., 18 figs

  18. Habitat and landscape characteristics underlying anuran community structure along an urban-rural gradient.

    Science.gov (United States)

    Pillsbury, Finn C; Miller, James R

    2008-07-01

    Urbanization has been cited as an important factor in worldwide amphibian declines, and although recent work has illustrated the important influence of broad-scale ecological patterns and processes on amphibian populations, little is known about the factors structuring amphibian communities in urban landscapes. We therefore examined amphibian community responses to wetland habitat availability and landscape characteristics along an urban-rural gradient in central Iowa, USA, a region experiencing rapid suburban growth. We conducted call surveys at 61 wetlands to estimate anuran calling activity, and quantified wetland habitat structure and landscape context. We used canonical correspondence analysis (CCA) to examine patterns in anuran community structure and identify the most important variables associated with those patterns. Urban density at the landscape scale had a significant negative influence on overall anuran abundance and diversity. While every species exhibited a decrease in abundance with increasing urban density, this pattern was especially pronounced for species requiring post-breeding upland habitats. Anurans most affected by urbanization were those associated with short hydroperiods, early breeding activity, and substantial upland habitat use. We suggest that broad-scale landscape fragmentation is an important factor underlying anuran community structure in this region, possibly due to limitations on the accessibility of otherwise suitable habitat in fragmented urban landscapes. This study underscores the importance of a regional approach to amphibian conservation in urban and urbanizing areas; in fragmented landscapes, a network of interconnected wetland and upland habitats may be more likely to support a successful, diverse anuran community than will isolated sites.

  19. Structural integrity assessment and stress measurement of chasnupp-1 fuel assembly skeleton: under tensile loading condition

    Directory of Open Access Journals (Sweden)

    Waseem

    2017-01-01

    Full Text Available Fuel assembly (FA structure without fuel rods is called FA skeleton which is a long and flexible structure. This study has been made in an attempt to find the structural integrity of the Chashma Nuclear power plant-1 FA skeleton at room temperature. The finite element (FE analysis has been performed using ANSYS, in order to determine the elongation of the FA skeleton as well as the location of max. stress and stresses developed in axial direction under tensile load of 9800 N or 2 g being the FA handling or lifting load [Y. Zhang et al., Fuel Assembly Design Report, SNERDI, China, 1994]. The FE model of grids, guide thimbles with dash-pots and flow holes has been developed using Shell 181. It has been observed that FA skeleton elongation values obtained through FE analysis and experiment are comparable and show linear behaviors. Moreover, the values of stresses obtained at different locations of the guide thimbles are also comparable with the stress values of the experiment determined at the same locations through strain gauges. Therefore, validation of the FE methodology is confirmed. The values of stresses are less than the design limit of the materials used for the grid and the guide thimble. Therefore, the structural integrity criterion of CHASNUPP-1 FA skeleton is fulfilled safely.

  20. Structural integrity assessment and stress measurement of chasnupp-1 fuel assembly skeleton: under tensile loading condition

    Science.gov (United States)

    Waseem; Siddiqui, Ashfaq Ahmad; Murtaza, Ghulam; Maqbool, Abu Baker

    2017-12-01

    Fuel assembly (FA) structure without fuel rods is called FA skeleton which is a long and flexible structure. This study has been made in an attempt to find the structural integrity of the Chashma Nuclear power plant-1 FA skeleton at room temperature. The finite element (FE) analysis has been performed using ANSYS, in order to determine the elongation of the FA skeleton as well as the location of max. stress and stresses developed in axial direction under tensile load of 9800 N or 2 g being the FA handling or lifting load [Y. Zhang et al., Fuel Assembly Design Report, SNERDI, China, 1994]. The FE model of grids, guide thimbles with dash-pots and flow holes has been developed using Shell 181. It has been observed that FA skeleton elongation values obtained through FE analysis and experiment are comparable and show linear behaviors. Moreover, the values of stresses obtained at different locations of the guide thimbles are also comparable with the stress values of the experiment determined at the same locations through strain gauges. Therefore, validation of the FE methodology is confirmed. The values of stresses are less than the design limit of the materials used for the grid and the guide thimble. Therefore, the structural integrity criterion of CHASNUPP-1 FA skeleton is fulfilled safely.