Rigidity Sensing Explained by Active Matter Theory
Marcq, Philippe; Yoshinaga, Natsuhiko; Prost, Jacques
2011-01-01
The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. We rationalize this observation using active matter theory, and propose that adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility.
The theory of pseudo-rigid bodies
Cohen, Harley
1988-01-01
This monograph concerns the development, analysis, and application of the theory of pseudo-rigid bodies. It collects together our work on that subject over the last five years. While some results have appeared else where, much of the work is new. Our objective in writing this mono graph has been to present a new theory of the deformation of bodies, one that has not only a firm theoretical basis, but also the simplicity to serve as an effective tool in practical problems. Consequently, the main body of the treatise is a multifaceted development of the theory, from foundations to explicit solutions to linearizations to methods of approximation. The fact that this variety of aspects, each examined in considerable detail, can be collected together in a single, unified treat ment gives this theory an elegance that we feel sets it apart from many others. While our goal has always been to give a complete treatment of the theory as it now stands, the work here is not meant to be definitive. Theories are not ent...
Quantum theory of gauge fields and rigid processes calculation
International Nuclear Information System (INIS)
Andreev, I.V.
1981-01-01
Elementary statement of the basic data on the nature of quark interactions and their role in the high energy processes is presented in the first part of the paper. The second part of the paper deals with gauge theory (GT) of strong interactions (chromodynamics (CD)) and its application in calculation of rigid processes with quark participation. It is based on the method of functional integration (MFI). A comparatively simple representation of the MFI in the quantum theory and formulation of the perturbation theory for gauge fields are given. A derivation of the rules of diagram technique is presented. Renormalization invariance of the theory and the basic for CD phenomenon of asymptotical freedom are discussed. Theory application in calculation of certain effects at high energies is considered. From the CD view point considered is a parton model on the base of which ''rigid'' stage of evolution of quark and gluon jets produced at high energies can be quantitatively described and some quantitative experimental tests of the CD are suggested [ru
Biomimetic model systems of rigid hair beds: Part I - Theory
Hood, Kaitlyn; Jammalamadaka, Mani S. S.; Hosoi, Anette
2017-11-01
Crustaceans - such as lobsters, crabs, and stomapods - have hairy appendages that they use to recognize and track odorants in the surrounding fluid. An array of rigid hairs impedes flow at different rates depending on the spacing between hairs and the Reynolds number, Re. At larger Reynolds numbers (Re >1), fluid travels through the hairs rather than around them, a phenomenon called leakiness. Crustaceans flick their appendages at different speeds in order to manipulate the leakiness between the hairs, allowing the hairs to either detect odors in a sample of fluid or collect a new sample. A single hair can be represented as a slender body attached at one end to a wall. Using both slender body theory and numerical methods, we observe that there is a region of flow around the hair that speeds up relative to the unobstructed flow. As the Reynolds number increases, this fast flow region moves closer to the hair. Using this model, we predict that an array of hairs can be engineered to have a desired leakiness profile.
International Nuclear Information System (INIS)
Getino, J.; Miguel, D.; Escapa, A.
2010-01-01
This paper is the first part of an investigation where we will present an analytical general theory of the rotation of the non-rigid Earth at the second order, which considers the effects of the interaction of the rotation of the Earth with itself, also named as the spin-spin coupling. Here, and as a necessary step in the development of that theory, we derive complete, explicit, analytical formulae of the rigid Earth rotation that account for the second-order rotation-rotation interaction. These expressions are not provided in this form by any current rigid Earth model. Working within the Hamiltonian framework established by Kinoshita, we study the second-order effects arising from the interaction of the main term in the Earth geopotential expansion with itself, and with the complementary term arising when referring the rotational motion to the moving ecliptic. To this aim, we apply a canonical perturbation method to solve analytically the canonical equations at the second order, determining the expressions that provide the nutation-precession, the polar motion, and the length of day. In the case of the motion of the equatorial plane, nutation-precession, we compare our general approach with the particular study for this motion developed by Souchay et al., showing the existence of new terms whose numerical values are within the truncation level of 0.1 μas adopted by those authors. These terms emerge as a consequence of not assuming in this work the same restrictive simplifications taken by Souchay et al. The importance of these additional contributions is that, as the analytical formulae show, they depend on the Earth model considered, in such a way that the fluid core resonance could amplify them significatively when extending this theory to the non-rigid Earth models.
Spontaneous breaking of N=2 to N=1 in rigid and local supersymmetric theories
Ferrara, Sergio; Porrati, Massimo
1996-01-01
We analyze the relation between rigid and local supersymmetric N=2 field theories, when half of the supersymmetries are spontaneously broken. In particular, we show that the recently found partial supersymmety breaking induced by electric and magnetic Fayet-Iliopoulos terms in rigid theories can be obtained by a suitable flat limit of previously constructed N=2 supergravity models with partial super-Higgs in the observable sector.
Non-rigid molecular group theory and its applications
International Nuclear Information System (INIS)
Balasubramanian, K.
1982-06-01
The use of generalized wreath product groups as representations of symmetry groups of nonrigid molecules is considered. Generating function techniques are outlined for nuclear spin statistics and character tables of the symmetry groups of nonrigid molecules. Several applications of nonrigid molecular group theory to NMR spectroscopy, rovibronic splitting and nuclear spin statistics of nonrigid molecules, molecular beam deflection and electric resonance experiments of weakly bound Van der Waal complexes, isomerization processes, configuration interaction calculations and the symmetry of crystals with structural distortions are described. 81 references
[The theory of postmortem rigidity: the history and an original concept].
Kil'diushov, E M; Tumanov, É V; Sokolova, Z Iu
2012-01-01
The original theory of postmortem rigidity has been developed and substantiated based on the concept of postmortem muscular contracture. It is postulated that the unrestricted growth of Ca2+ concentration in myoplasm of contractile cells during the immediate postmortal period brings the actin-myosine complex to the force generation state without subsequent relaxation.
DEFF Research Database (Denmark)
Sönmez, Ümit; Tutum, Cem Celal
2008-01-01
In this work, a new compliant bistable mechanism design is introduced. The combined use of pseudo-rigid-body model (PRBM) and the Elastica buckling theory is presented for the first time to analyze the new design. This mechanism consists of the large deflecting straight beams, buckling beams...... and the buckling Elastica solution for an original compliant mechanism kinematic analysis. New compliant mechanism designs are presented to highlight where such combined kinematic analysis is required....
A thermodynamically consistent constitutive theory for a rigid solid-stokesian fluid mixture
International Nuclear Information System (INIS)
Mattos, H.C.; Costa, M.L.M.; Sampaio, R.; Gama, R.M.S. da.
1992-01-01
This work is concerned with the modelling for the flow of a stokesian fluid through a rigid porous medium, using a Theory of Mixtures viewpoint. A systematic procedure to obtain constitutive relations that verify automatically the principle of objectivity and a local version of the second law of Thermodynamics is proposed. The prescription of two thermodynamic potentials for each constituent is sufficient to define a complete set of constitutive relations. (author)
Towards Sub-Microarsecond Rigid Earth Nutation Series in the Hamiltonian Theory
National Research Council Canada - National Science Library
Souchay, Jean; Folgueira, M
2000-01-01
...) are based on the works of Kinoshita (1977) and Wahr (1979). In Kinoshita's work, the rigid Earth nutation series were calculated by the application of the Hamiltonian canonical equations to the rotation of the rigid and elliptical Earth...
Dynamic Multi-Rigid-Body Systems with Concurrent Distributed Contacts: Theory and Examples
International Nuclear Information System (INIS)
TRINKLE, JEFFREY C.; TZITZOURIS, J.A.; PANG, J.S.
2001-01-01
Consider a system of rigid bodies with multiple concurrent contacts. The multi-rigid-body contact problem is to predict the accelerations of the bodies and the normal friction loads acting at the contacts. This paper presents theoretical results for the multi-rigid-body contact problem under the assumptions that one or more contacts occur over locally planar, finite regions and that friction forces are consistent with the maximum work inequality. Existence and uniqueness results are presented for this problem under mild assumptions on the system inputs. In addition, the performance of two different time-stepping methods for integrating the dynamics are compared on two simple multi-body systems
Directory of Open Access Journals (Sweden)
Dilip Sengupta
2013-01-01
Full Text Available Conventional posterior dynamic stabilization devices demonstrated a tendency towards highly rigid stabilization approximating that of titanium rods in flexion. In extension, they excessively offload the index segment, making the device as the sole load-bearing structure, with concerns of device failure. The goal of this study was to compare the kinematics and intradiscal pressure of monosegmental stabilization utilizing a new device that incorporates both a flexion and extension dampening spacer to that of rigid internal fixation and a conventional posterior dynamic stabilization device. The hypothesis was the new device would minimize the overloading of adjacent levels compared to rigid and conventional devices which can only bend but not stretch. The biomechanics were compared following injury in a human cadaveric lumbosacral spine under simulated physiological loading conditions. The stabilization with the new posterior dynamic stabilization device significantly reduced motion uniformly in all loading directions, but less so than rigid fixation. The evaluation of adjacent level motion and pressure showed some benefit of the new device when compared to rigid fixation. Posterior dynamic stabilization designs which both bend and stretch showed improved kinematic and load-sharing properties when compared to rigid fixation and when indirectly compared to existing conventional devices without a bumper.
dos Santos, G. J.; Linares, D. H.; Ramirez-Pastor, A. J.
2018-04-01
The phase behaviour of aligned rigid rods of length k (k-mers) adsorbed on two-dimensional square lattices has been studied by Monte Carlo (MC) simulations and histogram reweighting technique. The k-mers, containing k identical units (each one occupying a lattice site) were deposited along one of the directions of the lattice. In addition, attractive lateral interactions were considered. The methodology was applied, particularly, to the study of the critical point of the condensation transition occurring in the system. The process was monitored by following the fourth order Binder cumulant as a function of temperature for different lattice sizes. The results, obtained for k ranging from 2 to 7, show that: (i) the transition coverage exhibits a decreasing behaviour when it is plotted as a function of the k-mer size and (ii) the transition temperature, Tc, exhibits a power law dependence on k, Tc ∼k 0 , 4, shifting to higher values as k increases. Comparisons with an analytical model based on a generalization of the Bragg-Williams approximation (BWA) were performed in order to support the simulation technique. A significant qualitative agreement was obtained between BWA and MC results.
Krüger, Dennis M; Rathi, Prakash Chandra; Pfleger, Christopher; Gohlke, Holger
2013-07-01
The Constraint Network Analysis (CNA) web server provides a user-friendly interface to the CNA approach developed in our laboratory for linking results from rigidity analyses to biologically relevant characteristics of a biomolecular structure. The CNA web server provides a refined modeling of thermal unfolding simulations that considers the temperature dependence of hydrophobic tethers and computes a set of global and local indices for quantifying biomacromolecular stability. From the global indices, phase transition points are identified where the structure switches from a rigid to a floppy state; these phase transition points can be related to a protein's (thermo-)stability. Structural weak spots (unfolding nuclei) are automatically identified, too; this knowledge can be exploited in data-driven protein engineering. The local indices are useful in linking flexibility and function and to understand the impact of ligand binding on protein flexibility. The CNA web server robustly handles small-molecule ligands in general. To overcome issues of sensitivity with respect to the input structure, the CNA web server allows performing two ensemble-based variants of thermal unfolding simulations. The web server output is provided as raw data, plots and/or Jmol representations. The CNA web server, accessible at http://cpclab.uni-duesseldorf.de/cna or http://www.cnanalysis.de, is free and open to all users with no login requirement.
The New Keynesian Approach to Business Cycle Theory: Nominal and Real Rigidities
Monica Dobrescu
2012-01-01
At the heart of the Neoclassical synthesis lies the assumption that prices do not adjust instantly to equilibrate supply and demand. Under these circumstances, once the synthesis failed, economists naturally started to investigate whether the imperfect adjustment of prices could be logically inferred from realistic assumptions regarding the microeconomic environment, and subsequent research led to a variety of new non-walrasian theories regarding the functioning of markets. Thus, the non-walr...
Weiss, Asia; Whiteley, Walter
2014-01-01
This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme. Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology. The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...
Theory in Practice: Helping Providers Address Depression in Diabetes Care
Osborn, Chandra Y.; Kozak, Cindy; Wagner, Julie
2010-01-01
Introduction: A continuing education (CE) program based on the theory of planned behavior was designed to understand and improve health care providers' practice patterns in screening, assessing, and treating and/or referring patients with diabetes for depression treatment. Methods: Participants completed assessments of attitudes, confidence,…
Symmetry numbers for rigid, flexible, and fluxional molecules: theory and applications.
Gilson, Michael K; Irikura, Karl K
2010-12-16
The use of molecular simulations and ab initio calculations to predict thermodynamic properties of molecules has become routine. Such methods rely upon an accurate representation of the molecular partition function or configurational integral, which in turn often includes a rotational symmetry number. However, the reason for including the symmetry number is unclear to many practitioners, and there is also a need for a general prescription for evaluating the symmetry numbers of flexible molecules, i.e., for molecules with thermally active internal degrees of freedom, such as internal rotors. Surprisingly, we have been unable to find any complete and convincing explanations of these important issues in textbooks or the journal literature. The present paper aims to explain why symmetry numbers are needed and how their values should be determined. Both classical and quantum approaches are provided.
Provider integration and local market conditions: a contingency theory perspective.
Young, G J; Parker, V A; Charns, M P
2001-01-01
In recent years we have witnessed an expanding array of organizational arrangements for providing health care services in the U.S. These arrangements integrate previously independent providers at one or more points on the continuum of care. The presence of so many of these arrangements raises the question of whether certain types are more effective than are others to help providers adapt to their environment. This article discusses contingency theory as a conceptual lens for guiding empirical studies of the effectiveness of different types of arrangements.
Paradigm lost: provider concentration and the failure of market theory.
Vladeck, Bruce C
2014-06-01
In classic market theory, increased concentration among providers leads to higher prices for consumers. In the world of contemporary health policy, many stakeholders echo the classic market theory, blaming high health care prices on the increased concentration of providers, such as occurs when hospitals merge or are acquired by other hospitals. Thus, the consolidation of providers has become a convenient target for policy makers who want to be viewed as actively pursuing solutions to the growth in health care spending. Yet many of the factors fueling increased provider concentration are widely believed to be desirable, or practically unavoidable. Meanwhile, health care prices are increasing at historically low levels. Thus, there appears to be a contradiction between efforts to contain health care prices and the fact that aggressive policies aimed at reducing provider concentration might be ineffective and could even have the unintended effect of stunting positive developments. In a group of Health Affairs articles, William Sage and Paul Ginsburg and Gregory Pawlson respond to this conundrum by proposing a range of policy alternatives that, in this author's opinion, are either impractical or counterproductive because they have their roots in classical economic models of an industry with pervasive market failure. More effective and practical responses may be less theoretically elegant but more realistic and more reasonable. Project HOPE—The People-to-People Health Foundation, Inc.
Pukhlikov, Aleksandr
2013-01-01
Birational rigidity is a striking and mysterious phenomenon in higher-dimensional algebraic geometry. It turns out that certain natural families of algebraic varieties (for example, three-dimensional quartics) belong to the same classification type as the projective space but have radically different birational geometric properties. In particular, they admit no non-trivial birational self-maps and cannot be fibred into rational varieties by a rational map. The origins of the theory of birational rigidity are in the work of Max Noether and Fano; however, it was only in 1970 that Iskovskikh and Manin proved birational superrigidity of quartic three-folds. This book gives a systematic exposition of, and a comprehensive introduction to, the theory of birational rigidity, presenting in a uniform way, ideas, techniques, and results that so far could only be found in journal papers. The recent rapid progress in birational geometry and the widening interaction with the neighboring areas generate the growing interest ...
Halim, May Ling; Ruble, Diane N.; Tamis-LeMonda, Catherine S.; Zosuls, Kristina M.; Lurye, Leah E.; Greulich, Faith K.
2014-01-01
Many young children pass through a stage of gender appearance rigidity; girls insist on wearing dresses, often pink and frilly, whereas boys refuse to wear anything with a hint of femininity. In 2 studies, we investigated the prevalence of this apparent hallmark of early gender development and its relation to children's growing identification with…
Directory of Open Access Journals (Sweden)
Yongbin Chang
2011-09-01
Full Text Available By introducing a cutoff on the cumulative measure of a force, a unified kinetic theory is developed for both rigid-sphere and inverse-square force laws. The difference between the two kinds of interactions is characterized by a parameter, γ, which is 1 for rigid-sphere interactions and -3 for inverse-square force law interactions. The quantities governed by γ include the specific reaction rates, kernels, collision frequencies, arbitrarily high orders of transition moments, arbitrarily high orders of Fokker-Planck expansion (also called Kramers-Moyal expansion coefficients, and arbitrarily high orders of energy exchange rates. The cutoff constants are shown to be incomplete gamma functions of different orders. The widely used cutoff constant in plasma physics (usually known as Coulomb logarithm is found to be exactly the zeroth order of the incomplete gamma function. The well known Arrhenius reaction rate formula comes from the first order of the incomplete gamma functions, while the negative first order can be used for fitting the fusion reaction rate between deuterium and tritium.
Using attribution theory to examine community rehabilitation provider stigma.
Strauser, David R; Ciftci, Ayse; O'Sullivan, Deirdre
2009-03-01
This study builds on existing research investigating the stigma-reducing strategies specific to rehabilitation service providers by comparing differences in education levels and degree of contact among rehabilitation service providers. Rehabilitation service providers with master's level and bachelor level education showed significant differences in their stigmatizing tendencies on subscales of controllability and stability for different categories of disabilities. Specifically, service providers with a master's degree had more stigmatizing beliefs for psychosis and cocaine addiction, compared with service providers with a bachelor's degree. Service providers with either a bachelor's degree or master's degree reported lower levels of stigma overall for five of the six categories of disability compared with their community college student counterparts. No differences were found for length of time working with persons with psychiatric disabilities.
International Nuclear Information System (INIS)
Asghar, Z.; Requena, G.; Boller, E.
2011-01-01
The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4 h spheroidization treatment is characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of α-Al matrix and a rigid long-range 3-D network of Al 7 Cu 4 Ni, Al 4 Cu 2 Mg 8 Si 7 , Al 2 Cu, Al 15 Si 2 (FeMn) 3 and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300 deg. C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20 vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ∼15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4 h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si.
... may include a pelvic exam, and possibly a rectal exam. The provider will ask questions about your ... Copyright 1997-2018, A.D.A.M., Inc. Duplication for commercial use must be authorized in writing ...
Tackling wicked problems: how theories of agency can provide new insights.
Varpio, Lara; Aschenbrener, Carol; Bates, Joanna
2017-04-01
This paper reviews why and how theories of agency can be used as analytical lenses to help health professions education (HPE) scholars address our community's wicked problems. Wicked problems are those that resist clear problem statements, defy traditional analysis approaches, and refuse definitive resolution (e.g. student remediation, assessments of professionalism, etc.). We illustrate how theories of agency can provide new insights into such challenges by examining the application of these theories to one particular wicked problem in HPE: interprofessional education (IPE). After searching the HPE literature and finding that theories of agency had received little attention, we borrowed techniques from narrative literature reviews to search databases indexing a broad scope of disciplines (i.e. ERIC, Web of Science, Scopus, MEDLINE and PubMed) for publications (1994-2014) that: (i) examined agency, or (ii) incorporated an agency-informed analytical perspective. The lead author identified the theories of agency used in these articles, and reviewed the texts on agency cited therein and the original sources of each theory. We identified 10 theories of agency that we considered to be applicable to HPE's wicked problems. To select a subset of theories for presentation in this paper, we discussed each theory in relation to some of HPE's wicked problems. Through debate and reflection, we unanimously agreed on the applicability of a subset of theories for illuminating HPE's wicked problems. This subset is described in this paper. We present four theories of agency: Butler's post-structural formulation; Giddens' sociological formulation; cultural historical activity theory's formulation, and Bandura's social cognitive psychology formulation. We introduce each theory and apply each to the challenges of engaging in IPE. Theories of agency can inform HPE scholarship in novel and generative ways. Each theory offers new insights into the roots of wicked problems and means for
Rigidity of Glasses and Macromolecules
Thorpe, M. F.
1998-03-01
The simple yet powerful ideas of percolation theory have found their way into many different areas of research. In this talk we show how RIGIDITY PERCOLATION can be studied at a similar level of sophistication, using a powerful new program THE PEBBLE GAME (D. J. Jacobs and M. F. Thorpe, Phys. Rev. E) 53, 3682 (1996). that uses an integer algorithm. This program can analyse the rigidity of two and three dimensional networks containing more than one million bars and joints. We find the total number of floppy modes, and find the critical behavior as the network goes from floppy to rigid as more bars are added. We discuss the relevance of this work to network glasses, and how it relates to experiments that involve the mechanical properties like hardness and elasticity of covalent glassy networks like Ge_xAs_ySe_1-x-y and dicuss recent experiments that suggest that the rigidity transition may be first order (Xingwei Feng, W. J.Bresser and P. Boolchand, Phys. Rev. Lett 78), 4422 (1997).. This approach is also useful in macromolecules and proteins, where detailed information about the rigid domain structure can be obtained.
Quantum charged rigid membrane
Energy Technology Data Exchange (ETDEWEB)
Cordero, Ruben [Departamento de Fisica, Escuela Superior de Fisica y Matematicas del I.P.N., Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, D.F. (Mexico); Molgado, Alberto [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Zacatecas Zac. (Mexico); Rojas, Efrain, E-mail: cordero@esfm.ipn.mx, E-mail: amolgado@fisica.uaz.edu.mx, E-mail: efrojas@uv.mx [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)
2011-03-21
The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.
Quantum charged rigid membrane
International Nuclear Information System (INIS)
Cordero, Ruben; Molgado, Alberto; Rojas, Efrain
2011-01-01
The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.
Gas-induced friction and diffusion of rigid rotors
Martinetz, Lukas; Hornberger, Klaus; Stickler, Benjamin A.
2018-05-01
We derive the Boltzmann equation for the rotranslational dynamics of an arbitrary convex rigid body in a rarefied gas. It yields as a limiting case the Fokker-Planck equation accounting for friction, diffusion, and nonconservative drift forces and torques. We provide the rotranslational friction and diffusion tensors for specular and diffuse reflection off particles with spherical, cylindrical, and cuboidal shape, and show that the theory describes thermalization, photophoresis, and the inverse Magnus effect in the free molecular regime.
Caulfield, Jay
2007-01-01
The purpose of this empirical research study was to investigate what motivates students to provide formative anonymous feedback to teachers regarding their perceptions of the teaching and learning experience in order to improve student learning. Expectancy theory, specifically Vroom's Model, was used as the conceptual framework for the study.…
Elasticity of Relativistic Rigid Bodies?
Smarandache, Florentin
2013-10-01
In the classical Twin Paradox, according to the Special Theory of Relativity, when the traveling twin blasts off from the Earth to a relative velocity v =√{/3 } 2 c with respect to the Earth, his measuring stick and other physical objects in the direction of relative motion shrink to half their lengths. How is that possible in the real physical world to have let's say a rigid rocket shrinking to half and then later elongated back to normal as an elastic material when it stops? What is the explanation for the traveler's measuring stick and other physical objects, in effect, return to the same length to their original length in the Stay-At-Home, but there is no record of their having shrunk? If it's a rigid (not elastic) object, how can it shrink and then elongate back to normal? It might get broken in such situation.
Associative memory through rigid origami
Murugan, Arvind; Brenner, Michael
2015-03-01
Mechanisms such as Miura Ori have proven useful in diverse contexts since they have only one degree of freedom that is easily controlled. We combine the theory of rigid origami and associative memory in frustrated neural networks to create structures that can ``learn'' multiple generic folding mechanisms and yet can be robustly controlled. We show that such rigid origami structures can ``recall'' a specific learned mechanism when induced by a physical impulse that only need resemble the desired mechanism (i.e. robust recall through association). Such associative memory in matter, seen before in self-assembly, arises due to a balance between local promiscuity (i.e., many local degrees of freedom) and global frustration which minimizes interference between different learned behaviors. Origami with associative memory can lead to a new class of deployable structures and kinetic architectures with multiple context-dependent behaviors.
Birationally rigid varieties. I. Fano varieties
International Nuclear Information System (INIS)
Pukhlikov, A V
2007-01-01
The theory of birational rigidity of rationally connected varieties generalises the classical rationality problem. This paper gives a survey of the current state of this theory and traces its history from Noether's theorem and the Lueroth problem to the latest results on the birational superrigidity of higher-dimensional Fano varieties. The main components of the method of maximal singularities are considered.
Walker, Theodore, Jr.
2011-10-01
Anthropic reasoning about observation selection effects upon the appearance of cosmic providential fine-tuning (fine-tuning that provides for life) is often motivated by a desire to avoid theological implications (implications favoring the idea of a divine cosmic provider) without appealing to sheer lucky-for-us-cosmic-jackpot happenstance and coincidence. Cosmic coincidence can be rendered less incredible by appealing to a multiverse context. Cosmic providence can be rendered non-theological by appealing to an agent-less providential purpose, or by appealing to less-than-omnipresent/local providers, such as alien intelligences creating life- providing baby universes. Instead of choosing either cosmic coincidence or cosmic providence, as though they were mutually exclusive; it is better to accept both. Neoclassical thought accepts coincidence and providence, plus many local providers and one omnipresent provider. Moreover, fundamental observation selection theory should distinguish the many local observers of some events from the one omnipresent observer of all events. Accepting both coincidence and providence avoids classical theology (providence without coincidence) and classical atheism (coincidence without providence), but not neoclassical theology (providence with coincidence). Cosmology cannot avoid the idea of an all-inclusive omnipresent providential dice-throwing living-creative whole of reality, an idea essential to neoclassical theology, and to neoclassical cosmology.
Directory of Open Access Journals (Sweden)
Ekkehard Krüger
2015-05-01
Full Text Available The paper presents the group theory of optimally-localized and symmetry-adapted Wannier functions in a crystal of any given space group G or magnetic group M. Provided that the calculated band structure of the considered material is given and that the symmetry of the Bloch functions at all of the points of symmetry in the Brillouin zone is known, the paper details whether or not the Bloch functions of particular energy bands can be unitarily transformed into optimally-localized Wannier functions symmetry-adapted to the space group G, to the magnetic group M or to a subgroup of G or M. In this context, the paper considers usual, as well as spin-dependent Wannier functions, the latter representing the most general definition of Wannier functions. The presented group theory is a review of the theory published by one of the authors (Ekkehard Krüger in several former papers and is independent of any physical model of magnetism or superconductivity. However, it is suggested to interpret the special symmetry of the optimally-localized Wannier functions in the framework of a nonadiabatic extension of the Heisenberg model, the nonadiabatic Heisenberg model. On the basis of the symmetry of the Wannier functions, this model of strongly-correlated localized electrons makes clear predictions of whether or not the system can possess superconducting or magnetic eigenstates.
Dreison, Kimberly C; White, Dominique A; Bauer, Sarah M; Salyers, Michelle P; McGuire, Alan B
2018-01-01
Limited progress has been made in reducing burnout in mental health professionals. Accordingly, we identified factors that might protect against burnout and could be productive focal areas for future interventions. Guided by self-determination theory, we examined whether supervisor autonomy support, self-efficacy, and staff cohesion predict provider burnout. 358 staff from 13 agencies completed surveys. Higher levels of supervisor autonomy support, self-efficacy, and staff cohesion were predictive of lower burnout, even after accounting for job demands. Although administrators may be limited in their ability to reduce job demands, our findings suggest that increasing core job resources may be a viable alternative.
Rigid cohomology over Laurent series fields
Lazda, Christopher
2016-01-01
In this monograph, the authors develop a new theory of p-adic cohomology for varieties over Laurent series fields in positive characteristic, based on Berthelot's theory of rigid cohomology. Many major fundamental properties of these cohomology groups are proven, such as finite dimensionality and cohomological descent, as well as interpretations in terms of Monsky-Washnitzer cohomology and Le Stum's overconvergent site. Applications of this new theory to arithmetic questions, such as l-independence and the weight monodromy conjecture, are also discussed. The construction of these cohomology groups, analogous to the Galois representations associated to varieties over local fields in mixed characteristic, fills a major gap in the study of arithmetic cohomology theories over function fields. By extending the scope of existing methods, the results presented here also serve as a first step towards a more general theory of p-adic cohomology over non-perfect ground fields. Rigid Cohomology over Laurent Series Fields...
Tai, Bik-Wai Bilvick; Hata, Micah; Wu, Stephanie; Frausto, Sonya; Law, Anandi V
2016-10-01
Lack of familiarity with proper medication disposal options among patients can lead to personal and environmental safety concerns, besides signalling non-adherence. Given that community pharmacists are in a position to educate patients, this study assessed community pharmacists' knowledge on medication disposal and examined the utility of the theory of planned behaviour (TPB) in predicting their intention to provide medication disposal education to their patients. A cross-sectional, self-administered survey was distributed to community pharmacists in California. Descriptive statistics were reported for all survey items. Cronbach's alpha and Pearson correlation were used to determine the reliability for the four TPB constructs (attitude, subjective norm, perceived behavioural control and intention). Multiple linear regressions were performed to predict intent using the other three TPB constructs. Pharmacists (n = 142) demonstrated a positive intention to provide education (mean = 5.91 ± 1.22; range: 2 to 8), but most (67.9%) provided this information once a month or less. Attitude (β = 0.266, P = 0.001), subjective norm (β = 0.333, P behavioural control (β = 0.211, P = 0.009) were significant predictors of intention, accounting for 40.8% of the variance in intention to provide disposal education. Scale reliability ranged from 0.596 to 0.619 for the four constructs. Few pharmacists accurately selected all of the appropriate recommendations of disposal for non-controlled and controlled substances (15.9% and 10.1%, respectively). Pharmacists showed favourable attitude, subjective norm, perceived behaviour control and intention in providing such education. However, their knowledge in this area may be lacking and they are not consistently providing this information to their patients. © 2016 John Wiley & Sons, Ltd.
Competence in providing mental health care: a grounded theory analysis of nurses' experiences.
Sharrock, Julie; Happell, Brenda
In view of the evidence that general nurses have difficulty in caring for patients experiencing mental health problems, the aim of this study was to explore and describe the subjective experience of nurses in providing care for this client group. A grounded theory approach was used. The data were collected via semi-structured individual interviews and analysed using the constant comparative method. The study was conducted with nurses from general health care settings that provide medical and surgical care and treatment. Four nurses who were completing their second year post graduation participated in the study. The experiences of providing care for people experiencing a mental illness as described by participants. The findings indicated the nurses were striving for competence in the provision of mental health care. They acknowledged the mental health needs of patients and their right to quality care. This study supports the notion that general nurses lack confidence when caring for patients with mental health problems in medical and surgical settings. It also highlights a discrepancy between the holistic framework encouraged at undergraduate level and what is experienced in practice.
Effect of rigid inclusions on sintering
International Nuclear Information System (INIS)
Rahaman, M.N.; De Jonghe, L.C.
1988-01-01
The predictions of recent theoretical studies on the effect of inert, rigid inclusions on the sintering of ceramic powder matrices are examined and compared with experimental data. The densification of glass matrix composites with inclusion volume fractions of ≤0.15 can be adequately explained by Scherer's theory for viscous sintering with rigid inclusions. Inclusions cause a vast reduction in the densification rates of polycrystalline matrix composites even at low inclusion volume fractions. Models put forward to explain the sintering of polycrystalline matrix composites are discussed
Rigid supersymmetry with boundaries
Energy Technology Data Exchange (ETDEWEB)
Belyaev, D.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Van Nieuwenhuizen, P. [State Univ. of New York, Stony Brook, NY (United States). C.N. Yang Inst. for Theoretical Physics
2008-01-15
We construct rigidly supersymmetric bulk-plus-boundary actions, both in x-space and in superspace. For each standard supersymmetric bulk action a minimal supersymmetric bulk-plus-boundary action follows from an extended F- or D-term formula. Additional separately supersymmetric boundary actions can be systematically constructed using co-dimension one multiplets (boundary superfields). We also discuss the orbit of boundary conditions which follow from the Euler-Lagrange variational principle. (orig.)
Geometry, rigidity, and group actions
Farb, Benson; Zimmer, Robert J
2011-01-01
The study of group actions is more than a hundred years old but remains to this day a vibrant and widely studied topic in a variety of mathematic fields. A central development in the last fifty years is the phenomenon of rigidity, whereby one can classify actions of certain groups, such as lattices in semi-simple Lie groups. This provides a way to classify all possible symmetries of important spaces and all spaces admitting given symmetries. Paradigmatic results can be found in the seminal work of George Mostow, Gergory Margulis, and Robert J. Zimmer, among others.The p
Anti-synchronization of the rigid body exhibiting chaotic dynamics ...
African Journals Online (AJOL)
Based on a method derived from nonlinear control theory, we present a ... In this framework, the active control technique is modified and employed to design control ... state space of the two rigid bodies was verified by numerical simulations.
Young, S H
2003-01-01
The ideology and pronouncements of the Australian Government in introducing 'competitive neutrality' to the public sector has improved efficiency and resource usage. In the health sector, the Human Services Department directed that non-clinical and clinical areas be market tested through benchmarking services against the private sector, with the possibility of outsourcing. These services included car parking, computing, laundry, engineering, cleaning, catering, medical imaging (radiology), pathology, pharmacy, allied health and general practice. Managers, when they choose between outsourcing, and internal servicing and production, would thus ideally base their decision on economic principles. Williamson's transaction cost theory studies the governance mechanisms that can be used to achieve economic efficiency and proposes that the optimal organisation structure is that which minimises transaction costs or the costs of exchange. Williamson proposes that four variables will affect such costs, namely: (i) frequency of exchange; (ii) asset specificity; (iii) environmental uncertainty; and (iv) threat of opportunism. This paper provides evidence from a rural public hospital and examines whether Williamson's transaction cost theory is applicable. Case study research operates within the interpretivism paradigm and is used in this research to uncover why the outsourcing decision was made. Such research aims to study real-life experiences by examining the way people think and act and, in contrast to positivism, allows the interviewer to participate to better understand the details and features of the experiences. In the present research, individual interviews were conducted with managers of the hospital and owners and staff of the vendor organisations using semi- and unstructured questions to ascertain the extent of, and processes used in, outsourcing specific functional areas, and areas that were not outsourced. Pathology, radiology, dental technician services and lawn
Marco Guerrazzi; Nicola Meccheri
2009-01-01
This paper offers a critical discussion of the concept of labour market rigidity relevant to explaining unemployment. Starting from Keynes’s own view, we discuss how the concept of labour market flexibility has changed over time, involving nominal or real wage flexibility, contract flexibility or labour market institution flexibility. We also provide a critical assessment of the factors that lead the search framework highlighting labour market rigidities (frictions) to challenge the more wide...
Kinematic analysis of parallel manipulators by algebraic screw theory
Gallardo-Alvarado, Jaime
2016-01-01
This book reviews the fundamentals of screw theory concerned with velocity analysis of rigid-bodies, confirmed with detailed and explicit proofs. The author additionally investigates acceleration, jerk, and hyper-jerk analyses of rigid-bodies following the trend of the velocity analysis. With the material provided in this book, readers can extend the theory of screws into the kinematics of optional order of rigid-bodies. Illustrative examples and exercises to reinforce learning are provided. Of particular note, the kinematics of emblematic parallel manipulators, such as the Delta robot as well as the original Gough and Stewart platforms are revisited applying, in addition to the theory of screws, new methods devoted to simplify the corresponding forward-displacement analysis, a challenging task for most parallel manipulators. Stands as the only book devoted to the acceleration, jerk and hyper-jerk (snap) analyses of rigid-body by means of screw theory; Provides new strategies to simplify the forward kinematic...
Directory of Open Access Journals (Sweden)
Madjar Nir
2012-01-01
Full Text Available Abstract Background Psychosocial competence and frustration tolerance are important characteristics of skilled medical professionals. In the present study we explored the usefulness of applying a comprehensive motivational theory (Goal orientations, for this purpose. According to goal orientation theory, learning motivation is defined as the general goals students pursue during learning (either mastery goals - gaining new knowledge; or performance goals - gaining a positive evaluation of competence or avoiding negative evaluation. Perceived psychosocial abilities are a desirable outcome, and low frustration tolerance (LFT, is a negative feature of student behavior. The hypothesis was that the mastery goal would be positively associated with psychosocial abilities while performance goals would be positively associated with LFT. Methods 143 first-year medical students completed at the end of an annual doctor-patient communication course a structured questionnaire that included measures of learning goal orientations (assessed by Pattern of Adaptive Learning Scale - PALS, psychosocial abilities (assessed by Psychological Medicine Inventory- student version -PMI-S and Low Frustration Tolerance (LFT. Results All study variables were found reliable (Cronbach's α ranged from .66 to .90 and normally distributed. Hierarchical multiple regression analysis revealed significant associations supporting the hypotheses. The mastery goal orientation was positively associated with perceived psychosocial abilities (PMI-S (β = .16, p Conclusions The results suggest that the goal orientations theory may be a useful theoretical framework for understanding and facilitating learning motivation among medical students. Limitations and suggestions for practice within medical education context are discussed.
Madjar, Nir; Bachner, Yaacov G; Kushnir, Talma
2012-01-12
Psychosocial competence and frustration tolerance are important characteristics of skilled medical professionals. In the present study we explored the usefulness of applying a comprehensive motivational theory (Goal orientations), for this purpose. According to goal orientation theory, learning motivation is defined as the general goals students pursue during learning (either mastery goals - gaining new knowledge; or performance goals - gaining a positive evaluation of competence or avoiding negative evaluation). Perceived psychosocial abilities are a desirable outcome, and low frustration tolerance (LFT), is a negative feature of student behavior. The hypothesis was that the mastery goal would be positively associated with psychosocial abilities while performance goals would be positively associated with LFT. 143 first-year medical students completed at the end of an annual doctor-patient communication course a structured questionnaire that included measures of learning goal orientations (assessed by Pattern of Adaptive Learning Scale - PALS), psychosocial abilities (assessed by Psychological Medicine Inventory- student version -PMI-S) and Low Frustration Tolerance (LFT). All study variables were found reliable (Cronbach's α ranged from .66 to .90) and normally distributed. Hierarchical multiple regression analysis revealed significant associations supporting the hypotheses. The mastery goal orientation was positively associated with perceived psychosocial abilities (PMI-S) (β = .16, p frustration tolerance (β = -.22, p frustration tolerance (β = .36, p < .001). The results suggest that the goal orientations theory may be a useful theoretical framework for understanding and facilitating learning motivation among medical students. Limitations and suggestions for practice within medical education context are discussed.
Tile-based rigidization surface parametric design study
Giner Munoz, Laura; Luntz, Jonathan; Brei, Diann; Kim, Wonhee
2018-03-01
Inflatable technologies have proven useful in consumer goods as well as in more recent applications including civil structures, aerospace, medical, and robotics. However, inflatable technologies are typically lacking in their ability to provide rigid structural support. Particle jamming improves upon this by providing structures which are normally flexible and moldable but become rigid when air is removed. Because these are based on an airtight bladder filled with loose particles, they always occupy the full volume of its rigid state, even when not rigidized. More recent developments in layer jamming have created thin, compact rigidizing surfaces replacing the loose volume of particles with thinly layered surface materials. Work in this area has been applied to several specific applications with positive results but have not generally provided the broader understanding of the rigidization performance as a function of design parameters required for directly adapting layer rigidization technology to other applications. This paper presents a parametric design study of a new layer jamming vacuum rigidization architecture: tile-based vacuum rigidization. This form of rigidization is based on layers of tiles contained within a thin vacuum bladder which can be bent, rolled, or otherwise compactly stowed, but when deployed flat, can be vacuumed and form a large, flat, rigid plate capable of supporting large forces both localized and distributed over the surface. The general architecture and operation detailing rigidization and compliance mechanisms is introduced. To quantitatively characterize the rigidization behavior, prototypes rigidization surfaces are fabricated and an experimental technique is developed based on a 3-point bending test. Performance evaluation metrics are developed to describe the stiffness, load-bearing capacity, and internal slippage of tested prototypes. A set of experimental parametric studies are performed to better understand the impact of
Rigid polyurethane and kenaf core composite foams
Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...
Topological orders in rigid states
International Nuclear Information System (INIS)
Wen, X.G.
1990-01-01
The authors study a new kind of ordering topological order in rigid states (the states with no local gapless excitations). This paper concentrates on characterization of the different topological orders. As an example the authors discuss in detail chiral spin states of 2+1 dimensional spin systems. Chiral spin states are described by the topological Chern-Simons theories in the continuum limit. The authors show that the topological orders can be characterized by a non-Abelian gauge structure over the moduli space which parametrizes a family of the model Hamiltonians supporting topologically ordered ground states. In 2 + 1 dimensions, the non-Abelian gauge structure determines possible fractional statistics of the quasi-particle excitations over the topologically ordered ground states. The dynamics of the low lying global excitations is shown to be independent of random spatial dependent perturbations. The ground state degeneracy and the non-Abelian gauge structures discussed in this paper are very robust, even against those perturbations that break translation symmetry. The authors also discuss the symmetry properties of the degenerate ground states of chiral spin states. The authors find that some degenerate ground states of chiral spin states on torus carry non-trivial quantum numbers of the 90 degrees rotation
Torsional Rigidity of Minimal Submanifolds
DEFF Research Database (Denmark)
Markvorsen, Steen; Palmer, Vicente
2006-01-01
We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...
Evaluation for rigidity of box construction of nuclear reactor building
International Nuclear Information System (INIS)
Yamakawa, Tetsuo
1979-01-01
A huge box-shaped structure (hereafter, called box construction) of reinforced concrete is presently utilized as the reactor building structure in nuclear power plants. Evaluation of the rigidity of the huge box construction is required for making a vibration analysis model of nuclear reactor buildings. It is necessary to handle the box construction as the plates to which the force in plane is applied. This paper describes that the bending theory in elementary beam theory is equivalent to a peculiar, orthogonally anisotropic plate, the shearing rigidity and film rigidity in y direction of which are put to infinity and the Poisson's ratio is put to zero, viewed from the two-dimensional theory of elasticity. The form factor of 1.2 for shearing deformation in rectangular cross section was calculated from the parabolic distribution of shearing stress intensity, and it is the maximum value. The factor is equal to 1.2 for slender beams, but smaller than 1.2 for short and thick beams, having tendency to converge to 1.0. The non-conformity of boundary conditions regarding the shearing force at the both ends of cantilevers does not affect very seriously the evaluation of shearing rigidity. From the above results, it was found that the application of the theory to the box construction was able to give the rigidity evaluation with sufficient engineering accuracy. The theory can also be applied to the evaluation of tube type ultrahigh buildings. (Wakatsuki, Y.)
School health promotion providers' roles in practice and theory: results from a case study.
Teutsch, Friedrich; Gugglberger, Lisa; Dür, Wolfgang
2015-01-01
Implementation is critical to the success of health promotion (HP) in schools, but little is known about how schools can best be assisted during this process. This article focuses on Austrian HP providers and aspects their roles incorporate. To investigate the providers' role in the practice of HP implementation and how it differs from its official description. On the basis of these findings, implications are suggested. The data were gathered within the framework of an explorative case study of complex HP interventions. We draw on four interviews with HP organisation staff, five documents from the providers' organisations and seven interviews with school staff from three schools. In practice, providers took up different responsibilities, e.g., acting as emotional support to school staff and supporting the documentation of projects, guided more by the schools' needs than by the programmes they are helping to implement. Providers focused mostly on the implementation of single activities and did little to emphasize the necessity of organisational change. Our findings suggest that providers' background in health should be complemented by a deeper understanding of the importance of organisational change to further support HP implementation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Kisley, Lydia; Chen, Jixin; Mansur, Andrea P; Shuang, Bo; Kourentzi, Katerina; Poongavanam, Mohan-Vivekanandan; Chen, Wen-Hsiang; Dhamane, Sagar; Willson, Richard C; Landes, Christy F
2014-02-11
Chromatographic protein separations, immunoassays, and biosensing all typically involve the adsorption of proteins to surfaces decorated with charged, hydrophobic, or affinity ligands. Despite increasingly widespread use throughout the pharmaceutical industry, mechanistic detail about the interactions of proteins with individual chromatographic adsorbent sites is available only via inference from ensemble measurements such as binding isotherms, calorimetry, and chromatography. In this work, we present the direct superresolution mapping and kinetic characterization of functional sites on ion-exchange ligands based on agarose, a support matrix routinely used in protein chromatography. By quantifying the interactions of single proteins with individual charged ligands, we demonstrate that clusters of charges are necessary to create detectable adsorption sites and that even chemically identical ligands create adsorption sites of varying kinetic properties that depend on steric availability at the interface. Additionally, we relate experimental results to the stochastic theory of chromatography. Simulated elution profiles calculated from the molecular-scale data suggest that, if it were possible to engineer uniform optimal interactions into ion-exchange systems, separation efficiencies could be improved by as much as a factor of five by deliberately exploiting clustered interactions that currently dominate the ion-exchange process only accidentally.
Rigid Residue Scan Simulations Systematically Reveal Residue Entropic Roles in Protein Allostery.
Directory of Open Access Journals (Sweden)
Robert Kalescky
2016-04-01
Full Text Available Intra-protein information is transmitted over distances via allosteric processes. This ubiquitous protein process allows for protein function changes due to ligand binding events. Understanding protein allostery is essential to understanding protein functions. In this study, allostery in the second PDZ domain (PDZ2 in the human PTP1E protein is examined as model system to advance a recently developed rigid residue scan method combining with configurational entropy calculation and principal component analysis. The contributions from individual residues to whole-protein dynamics and allostery were systematically assessed via rigid body simulations of both unbound and ligand-bound states of the protein. The entropic contributions of individual residues to whole-protein dynamics were evaluated based on covariance-based correlation analysis of all simulations. The changes of overall protein entropy when individual residues being held rigid support that the rigidity/flexibility equilibrium in protein structure is governed by the La Châtelier's principle of chemical equilibrium. Key residues of PDZ2 allostery were identified with good agreement with NMR studies of the same protein bound to the same peptide. On the other hand, the change of entropic contribution from each residue upon perturbation revealed intrinsic differences among all the residues. The quasi-harmonic and principal component analyses of simulations without rigid residue perturbation showed a coherent allosteric mode from unbound and bound states, respectively. The projection of simulations with rigid residue perturbation onto coherent allosteric modes demonstrated the intrinsic shifting of ensemble distributions supporting the population-shift theory of protein allostery. Overall, the study presented here provides a robust and systematic approach to estimate the contribution of individual residue internal motion to overall protein dynamics and allostery.
Natan, Merav Ben; Beyil, Valery; Neta, Okev
2009-12-01
A correlational design was used to examine nursing staff attitudes and subjective norms manifested in intended and actual care of drug users based on the Theory of Reasoned Action. One hundred and thirty-five nursing staff from three central Israeli hospitals completed a questionnaire examining theory-based variables as well as sociodemographic and professional characteristics. Most respondents reported a high to very high level of actual or intended care of drug users. Nurses' stronger intentions to provide quality care to drug users were associated with more positive attitudes. Nursing staff members had moderately negative attitudes towards drug users. Nurses were found to hold negative stereotypes of drug addict patients and most considered the management of this group difficult. Positive attitudes towards drug users, perceived expectations of others and perceived correctness of the behaviour are important in their effect on the intention of nurses to provide high-quality care to hospitalized patients addicted to drugs.
Modeling the Flexural Rigidity of Rod Photoreceptors
Haeri, Mohammad; Knox, Barry E.; Ahmadi, Aphrodite
2013-01-01
In vertebrate eyes, the rod photoreceptor has a modified cilium with an extended cylindrical structure specialized for phototransduction called the outer segment (OS). The OS has numerous stacked membrane disks and can bend or break when subjected to mechanical forces. The OS exhibits axial structural variation, with extended bands composed of a few hundred membrane disks whose thickness is diurnally modulated. Using high-resolution confocal microscopy, we have observed OS flexing and disruption in live transgenic Xenopus rods. Based on the experimental observations, we introduce a coarse-grained model of OS mechanical rigidity using elasticity theory, representing the axial OS banding explicitly via a spring-bead model. We calculate a bending stiffness of ∼105 nN⋅μm2, which is seven orders-of-magnitude larger than that of typical cilia and flagella. This bending stiffness has a quadratic relation to OS radius, so that thinner OS have lower fragility. Furthermore, we find that increasing the spatial frequency of axial OS banding decreases OS rigidity, reducing its fragility. Moreover, the model predicts a tendency for OS to break in bands with higher spring number density, analogous to the experimental observation that transgenic rods tended to break preferentially in bands of high fluorescence. We discuss how pathological alterations of disk membrane properties by mutant proteins may lead to increased OS rigidity and thus increased breakage, ultimately contributing to retinal degeneration. PMID:23442852
DEFF Research Database (Denmark)
Rijkhoff, Jan
2010-01-01
classes. Finally this article wants to claim that the distinction between rigid and flexible noun categories (a) adds a new dimension to current classifications of parts of speech systems, (b) correlates with certain grammatical phenomena (e.g. so-called number discord), and (c) helps to explain the parts......This article argues that in addition to the major flexible lexical categories in Hengeveld’s classification of parts of speech systems (Contentive, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members...... by the flexible item in the external world. I will then argue that flexible word classes constitute a proper category (i.e. they are not the result of a merger of some rigid word classes) in that members of flexible word categories display the same properties regarding category membership as members of rigid word...
International Nuclear Information System (INIS)
Stancanello, J.; Loeckx, D.; Francescon, P.; Calvedon, C.; Avanzo, M.; Cora, S.; Scalchi, P.; Cerveri, P.; Ferrigno, G.
2004-01-01
This work aims at comparing rigid, affine and Local Non Rigid (LNR) CT-3D Rotational Angiography (CT-3DRA) registrations based on mutual information. 10 cranial and 1 spinal cases have been registered by rigid and affine transformations; while LNR has been applied to the cases where residual deformation must be corrected. An example of CT-3DRA registration without regularization term and an example of LNR using the similarity criterion and the regularization term as well as 3D superposition of the 3DRA before and after the registration without the regularization term are presented. All the registrations performed by rigid transformation converged to an acceptable solution. The results about the robustness test in axial direction are reported. Conclusions: For cranial cases, affine transformation endowed with threshold-segmentation pre-processing can be considered the most favourable solution for almost all registrations; for some cases, LNR provides more accurate results. For the spinal case rigid transformation is the most suitable when immobilizing patient during examinations; in this case the increase of accuracy by using LNR registrations seems to be not significant
2013-01-01
Background Unsafe abortion is a major public health problem in Ghana; despite its liberal abortion law, access to safe, legal abortion in public health facilities is limited. Theory is often neglected as a tool for providing evidence to inform better practice; in this study we investigated the reasons for poor implementation of the policy in Ghana using Lipsky’s theory of street-level bureaucracy to better understand how providers shape and implement policy and how provider-level barriers might be overcome. Methods In-depth interviews were conducted with 43 health professionals of different levels (managers, obstetricians, midwives) at three hospitals in Accra, as well as staff from smaller and private sector facilities. Relevant policy and related documents were also analysed. Results Findings confirm that health providers’ views shape provision of safe-abortion services. Most prominently, providers experience conflicts between their religious and moral beliefs about the sanctity of (foetal) life and their duty to provide safe-abortion care. Obstetricians were more exposed to international debates, treaties, and safe-abortion practices and had better awareness of national research on the public health implications of unsafe abortions; these factors tempered their religious views. Midwives were more driven by fundamental religious values condemning abortion as sinful. In addition to personal views and dilemmas, ‘social pressures’ (perceived views of others concerning abortion) and the actions of facility managers affected providers’ decision to (openly) provide abortion services. In order to achieve a workable balance between these pressures and duties, providers use their ‘discretion’ in deciding if and when to provide abortion services, and develop ‘coping mechanisms’ which impede implementation of abortion policy. Conclusions The application of theory confirmed its utility in a lower-middle income setting and expanded its scope by showing that
Rigid multibody system dynamics with uncertain rigid bodies
Energy Technology Data Exchange (ETDEWEB)
Batou, A., E-mail: anas.batou@univ-paris-est.fr; Soize, C., E-mail: christian.soize@univ-paris-est.fr [Universite Paris-Est, Laboratoire Modelisation et Simulation Multi Echelle, MSME UMR 8208 CNRS (France)
2012-03-15
This paper is devoted to the construction of a probabilistic model of uncertain rigid bodies for multibody system dynamics. We first construct a stochastic model of an uncertain rigid body by replacing the mass, the center of mass, and the tensor of inertia by random variables. The prior probability distributions of the stochastic model are constructed using the maximum entropy principle under the constraints defined by the available information. The generators of independent realizations corresponding to the prior probability distribution of these random quantities are further developed. Then several uncertain rigid bodies can be linked to each other in order to calculate the random response of a multibody dynamical system. An application is proposed to illustrate the theoretical development.
Russell, Luke T; Coleman, Marilyn; Ganong, Lawrence H; Gayer, Debra
2016-05-01
Divorced parents face distinct challenges in providing care for chronically ill children. Children's residence in two households necessitates the development of family-specific strategies to ensure coparents' supervision of regimen adherence and the management of children's health care. Utilizing a risk and resilience perspective, a grounded theory study was conducted with 14 divorced parents of children with chronic illnesses. The importance of trust, gender, and relationships with third-party care providers emerged as key themes related to the development of effective coparenting relationships for maintaining children's health. Divorced parents were best able to support the management of their children's chronic conditions when care providers operated as neutral third parties and intermediaries. Collaborative family care may require health care practitioners to avoid being drawn into contentious inter-parental conflicts. © The Author(s) 2016.
Static friction between rigid fractal surfaces.
Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming
2015-09-01
Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.
Rigidly foldable origami gadgets and tessellations
Evans, Thomas A.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.
2015-01-01
Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented. PMID:26473037
Blast wave interaction with a rigid surface
International Nuclear Information System (INIS)
Josey, T.; Whitehouse, D.R.; Ripley, R.C.; Dionne, J.P.
2004-01-01
A simple model used to investigate blast wave interactions with a rigid surface is presented. The model uses a constant volume energy source analogue to predict pressure histories at gauges located directly above the charge. A series of two-dimensional axi-symmetric CFD calculations were performed, varying the height of the charge relative to the ground. Pressure histories, along with isopycnic plots are presented to evaluate the effects of placing a charge in close proximity to a rigid surface. When a charge is placed near a solid surface the pressure histories experienced at gauges above the charge indicate the presence of two distinct pressure peaks. The first peak is caused by the primary shock and the second peak is a result of the wave reflections from the rigid surface. As the distance from the charge to the wall is increased the magnitude of the second pressure peak is reduced, provided that the distance between the charge and the gauge is maintained constant. The simple model presented is able to capture significant, predictable flow features. (author)
Lateral rigidity of cracked concrete structures
International Nuclear Information System (INIS)
Castellani, A.; Chesi, C.
1979-01-01
Numerical results are discussed on the lateral rigidity of reinforced concrete structures with a given crack distribution. They have been favourably checked with experimental results for cylindrical shells under the effect of a thermal gradient producing vertical cracking or vertical plus horizontal cracking. The main effects characterizing the concrete behaviour are: (1) The shear transfer across a crack; (2) The shear transfer degradation after cyclic loading; (3) The tension stiffening provided by the concrete between crack and crack, in the normal stress transfer; (4) The temperature effect on the elastic moduli of concrete, when cracks are of thermal origin. Only the 1st effect is discussed on an experimental basis. Two broad cathegories of reinforced concrete structures have been investigated in this respect: shear walls of buildings and cylindrical containment structures. The main conclusions so far reached are: (1) Vertical cracks are unlikely to decrease the lateral rigidity to less than 80% of the original one, and to less than 90% when they do not involve the entire thickness of the wall; (2) The appearence of horizontal cracks can reduce the lateral rigidity by some 30% or more; (3) A noticeable but not yet evaluated influence is shown by cyclic loading. (orig.)
Rigidity-tuning conductive elastomer
Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel
2015-06-01
We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE-PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ˜6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE-PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE-PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation.
Rigidity-tuning conductive elastomer
International Nuclear Information System (INIS)
Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel
2015-01-01
We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE–PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ∼6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE–PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE–PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation. (paper)
Non-rigid image registration using bone growth model
DEFF Research Database (Denmark)
Bro-Nielsen, Morten; Gramkow, Claus; Kreiborg, Sven
1997-01-01
Non-rigid registration has traditionally used physical models like elasticity and fluids. These models are very seldom valid models of the difference between the registered images. This paper presents a non-rigid registration algorithm, which uses a model of bone growth as a model of the change...... between time sequence images of the human mandible. By being able to register the images, this paper at the same time contributes to the validation of the growth model, which is based on the currently available medical theories and knowledge...
Rigid particle revisited: Extrinsic curvature yields the Dirac equation
Energy Technology Data Exchange (ETDEWEB)
Deriglazov, Alexei, E-mail: alexei.deriglazov@ufjf.edu.br [Depto. de Matemática, ICE, Universidade Federal de Juiz de Fora, MG (Brazil); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk, Lenin Ave. 30 (Russian Federation); Nersessian, Armen, E-mail: arnerses@ysu.am [Yerevan State University, 1 Alex Manoogian St., Yerevan 0025 (Armenia); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk, Lenin Ave. 30 (Russian Federation)
2014-03-01
We reexamine the model of relativistic particle with higher-derivative linear term on the first extrinsic curvature (rigidity). The passage from classical to quantum theory requires a number of rather unexpected steps which we report here. We found that, contrary to common opinion, quantization of the model in terms of so(3.2)-algebra yields massive Dirac equation. -- Highlights: •New way of canonical quantization of relativistic rigid particle is proposed. •Quantization made in terms of so(3.2) angular momentum algebra. •Quantization yields massive Dirac equation.
Genus Ranges of 4-Regular Rigid Vertex Graphs.
Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin
2015-01-01
A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2 n vertices ( n > 1), we prove that all intervals [ a, b ] for all a genus ranges. For graphs with 2 n - 1 vertices ( n ≥ 1), we prove that all intervals [ a, b ] for all a genus ranges. We also provide constructions of graphs that realize these ranges.
Liang, L. L.; Arcus, V. L.; Heskel, M.; O'Sullivan, O. S.; Weerasinghe, L. K.; Creek, D.; Egerton, J. J. G.; Tjoelker, M. G.; Atkin, O. K.; Schipper, L. A.
2017-12-01
Temperature is a crucial factor in determining the rates of ecosystem processes such as leaf respiration (R) - the flux of plant respired carbon dioxide (CO2) from leaves to the atmosphere. Generally, respiration rate increases exponentially with temperature as modelled by the Arrhenius equation, but a recent study (Heskel et al., 2016) showed a universally convergent temperature response of R using an empirical exponential/polynomial model whereby the exponent in the Arrhenius model is replaced by a quadratic function of temperature. The exponential/polynomial model has been used elsewhere to describe shoot respiration and plant respiration. What are the principles that underlie these empirical observations? Here, we demonstrate that macromolecular rate theory (MMRT), based on transition state theory for chemical kinetics, is equivalent to the exponential/polynomial model. We re-analyse the data from Heskel et al. 2016 using MMRT to show this equivalence and thus, provide an explanation based on thermodynamics, for the convergent temperature response of R. Using statistical tools, we also show the equivalent explanatory power of MMRT when compared to the exponential/polynomial model and the superiority of both of these models over the Arrhenius function. Three meaningful parameters emerge from MMRT analysis: the temperature at which the rate of respiration is maximum (the so called optimum temperature, Topt), the temperature at which the respiration rate is most sensitive to changes in temperature (the inflection temperature, Tinf) and the overall curvature of the log(rate) versus temperature plot (the so called change in heat capacity for the system, ). The latter term originates from the change in heat capacity between an enzyme-substrate complex and an enzyme transition state complex in enzyme-catalysed metabolic reactions. From MMRT, we find the average Topt and Tinf of R are 67.0±1.2 °C and 41.4±0.7 °C across global sites. The average curvature (average
Rigid-plastic seismic design of reinforced concrete structures
DEFF Research Database (Denmark)
Costa, Joao Domingues; Bento, R.; Levtchitch, V.
2007-01-01
structural strength with respect to a pre-defined performance parameter using a rigid-plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing......In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed-the Rigid-Plastic Seismic Design (RPSD) method. This is a design procedure based on Non-Linear Time-History Analysis (NLTHA) for systems expected to perform in the non-linear range during a lifetime...... earthquake event. The theoretical background is the Theory of Plasticity (Rigid-Plastic Structures). Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required...
DEFF Research Database (Denmark)
Rijkhoff, Jan
2008-01-01
Studies in Language 32-3 (2008), 727-752. Special issue: Parts of Speech: Descriptive tools, theoretical constructs Jan Rijkhoff - On flexible and rigid nouns This article argues that in addition to the flexible lexical categories in Hengeveld’s classification of parts-of-speech systems (Contentive......, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members of flexible word classes are characterized by their vague semantics, which in the case of nouns means that values for the semantic features Shape...... and Homogeneity are either left undetermined or they are specified in such a way that they do not quite match the properties of the kind of entity denoted by the flexible item in the external world. I will then argue that flexible word classes constitute a proper category (i.e. they are not the result of a merger...
Functionally rigid bistable [2]rotaxanes
DEFF Research Database (Denmark)
Nygaard, Sune; Leung, Ken C-F; Aprahamian, Ivan
2007-01-01
defines an unambiguous distance of 1.5 nm over which the ring moves between the MPTTF and NP units. The degenerate NP/NP [2]rotaxane was used to investigate the shuttling barrier by dynamic 1H NMR spectroscopy for the movement of the CBPQT4+ ring across the new rigid spacer. It is evident from...... better control over the position of the ring component in the ground state but also for control over the location of the CBPQT4+ ring during solution-state switching experiments, triggered either chemically (1H NMR) or electrochemically (cyclic voltammetry). In this instance, the use of the rigid spacer......Two-station [2]rotaxanes in the shape of a degenerate naphthalene (NP) shuttle and a nondegenerate monopyrrolotetrathiafulvalene (MPTTF)/NP redox-controllable switch have been synthesized and characterized in solution. Their dumbbell-shaped components are composed of polyether chains interrupted...
Rigid body dynamics of mechanisms
Hahn, Hubert
2003-01-01
The second volume of Rigid Body Dynamics of Mechanisms covers applications via a systematic method for deriving model equations of planar and spatial mechanisms. The necessary theoretical foundations have been laid in the first volume that introduces the theoretical mechanical aspects of mechatronic systems. Here the focus is on the application of the modeling methodology to various examples of rigid-body mechanisms, simple planar ones as well as more challenging spatial problems. A rich variety of joint models, active constraints, plus active and passive force elements is treated. The book is intended for self-study by working engineers and students concerned with the control of mechanical systems, i.e. robotics, mechatronics, vehicles, and machine tools. The examples included are a likely source from which to choose models for university lectures.
Rigidity spectrum of Forbush decrease
International Nuclear Information System (INIS)
Sakakibara, S.; Munakata, K.; Nagashima, K.
1985-01-01
Using data from neutron monitors and muon telescopes at surface and underground stations, the average rigidity spectrum of Forbush decreases (Fds) during the period of 1978-1982 were obtained. Thirty eight Ed-events are classified into two groups, Hard Fd and Soft FD according to size of Fd at the Sakashita station. It is found that a spectral form of a fractional-power type (P to the-gamma sub 1 (P+P sub c) to the -gamma sub2) is more suitable than that of a power-exponential type or of a power type with an upper limiting rigidity. The best fitted spectrum of the fractional-power type is expressed by gamma sub1 = 0.37, gamma sub2 = 0.89 and P subc = 10 GV for Hard Fd and gamma sub1 = 0.77, gamma sub2 = 1.02 and P sub c - 14GV for Soft Fd
Signature of Thermal Rigidity Percolation
International Nuclear Information System (INIS)
Huerta, Adrián
2013-01-01
To explore the role that temperature and percolation of rigidity play in determining the macroscopic properties, we propose a model that adds translational degrees of freedom to the spins of the well known Ising hamiltonian. In particular, the Ising model illustrate the longstanding idea that the growth of correlations on approach to a critical point could be describable in terms of the percolation of some sort of p hysical cluster . For certain parameters of this model we observe two well defined peaks of C V , that suggest the existence of two kinds of p hysical percolation , namely connectivity and rigidity percolation. Thermal fluctuations give rise to two different kinds of elementary excitations, i.e. droplets and configuron, as suggested by Angell in the framework of a bond lattice model approach. The later is reflected in the fluctuations of redundant constraints that gives stability to the structure and correlate with the order parameter
Coherent distributions for the rigid rotator
Energy Technology Data Exchange (ETDEWEB)
Grigorescu, Marius [CP 15-645, Bucharest 014700 (Romania)
2016-06-15
Coherent solutions of the classical Liouville equation for the rigid rotator are presented as positive phase-space distributions localized on the Lagrangian submanifolds of Hamilton-Jacobi theory. These solutions become Wigner-type quasiprobability distributions by a formal discretization of the left-invariant vector fields from their Fourier transform in angular momentum. The results are consistent with the usual quantization of the anisotropic rotator, but the expected value of the Hamiltonian contains a finite “zero point” energy term. It is shown that during the time when a quasiprobability distribution evolves according to the Liouville equation, the related quantum wave function should satisfy the time-dependent Schrödinger equation.
A rigid porous filter and filtration method
Energy Technology Data Exchange (ETDEWEB)
Chiang, Ta-Kuan; Straub, Douglas, Straub L.; Dennis, Richard A.
1998-12-01
The present invention involves a porous rigid filter comprising a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulate from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulate. The present filter has the advantage of requiring fewer filter elements due to the high surface area- to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.
Mechanical Characterization of Rigid Polyurethane Foams
Energy Technology Data Exchange (ETDEWEB)
Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Mechanics of Materials
2014-12-01
Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.
Torsional rigidity, isospectrality and quantum graphs
International Nuclear Information System (INIS)
Colladay, Don; McDonald, Patrick; Kaganovskiy, Leon
2017-01-01
We study torsional rigidity for graph and quantum graph analogs of well-known pairs of isospectral non-isometric planar domains. We prove that such isospectral pairs are distinguished by torsional rigidity. (paper)
Directory of Open Access Journals (Sweden)
Timpka Toomas
2009-12-01
Full Text Available Abstract Background Computerized provider order entry (CPOE systems have been introduced to reduce medication errors, increase safety, improve work-flow efficiency, and increase medical service quality at the moment of prescription. Making the impact of CPOE systems more observable may facilitate their adoption by users. We set out to examine factors associated with the adoption of a CPOE system for inter-organizational and intra-organizational care. Methods The diffusion of innovation theory was used to understand physicians' and nurses' attitudes and thoughts about implementation and use of the CPOE system. Two online survey questionnaires were distributed to all physicians and nurses using a CPOE system in county-wide healthcare organizations. The number of complete questionnaires analyzed was 134 from 200 nurses (67.0% and 176 from 741 physicians (23.8%. Data were analyzed using descriptive-analytical statistical methods. Results More nurses (56.7% than physicians (31.3% stated that the CPOE system introduction had worked well in their clinical setting (P P = P = 0.041. We found that in particular the received relative advantages of the CPOE system were estimated to be significantly (P P Conclusions Qualifications for CPOE adoption as defined by three attributes of diffusion of innovation theory were not satisfied in the study setting. CPOE systems are introduced as a response to the present limitations in paper-based systems. In consequence, user expectations are often high on their relative advantages as well as on a low level of complexity. Building CPOE systems therefore requires designs that can provide rather important additional advantages, e.g. by preventing prescription errors and ultimately improving patient safety and safety of clinical work. The decision-making process leading to the implementation and use of CPOE systems in healthcare therefore has to be improved. As any change in health service settings usually faces resistance
Rigidity of monodromies for Appell's hypergeometric functions
Directory of Open Access Journals (Sweden)
Yoshishige Haraoka
2015-01-01
Full Text Available For monodromy representations of holonomic systems, the rigidity can be defined. We examine the rigidity of the monodromy representations for Appell's hypergeometric functions, and get the representations explicitly. The results show how the topology of the singular locus and the spectral types of the local monodromies work for the study of the rigidity.
International Nuclear Information System (INIS)
Moon, Won Joo; Min, Oak Key; Kim, Yong Woo
1998-01-01
To improve the convergence and the accuracy of a finite element, the finite element has to describe not only displacement and stress distributions in a static analysis but also rigid body displacements. In this paper, we consider the in-plane-deformable curved beam element to understand the descriptive capability of rigid body displacements of a finite element. We derive the rigid body displacement fields of a single finite element under various essential boundary conditions when the nodal displacements are caused by the rigid body displacement. We also examine the rigid body displacement fields of a quadratic curved beam element by employing the reduced minimization theory
Rigid body formulation in a finite element context with contact interaction
Refachinho de Campos, Paulo R.; Gay Neto, Alfredo
2018-03-01
The present work proposes a formulation to employ rigid bodies together with flexible bodies in the context of a nonlinear finite element solver, with contact interactions. Inertial contributions due to distribution of mass of a rigid body are fully developed, considering a general pole position associated with a single node, representing a rigid body element. Additionally, a mechanical constraint is proposed to connect a rigid region composed by several nodes, which is useful for linking rigid/flexible bodies in a finite element environment. Rodrigues rotation parameters are used to describe finite rotations, by an updated Lagrangian description. In addition, the contact formulation entitled master-surface to master-surface is employed in conjunction with the rigid body element and flexible bodies, aiming to consider their interaction in a rigid-flexible multibody environment. New surface parameterizations are presented to establish contact pairs, permitting pointwise interaction in a frictional scenario. Numerical examples are provided to show robustness and applicability of the methods.
THE RIGIDITY OF THE EARTH'S INNER CORE
Directory of Open Access Journals (Sweden)
K. E. BULLEN
1953-06-01
Full Text Available The purpose of this paper is to examine and assess, in the
light of recent evidence, the theory lliat the Earth's inner core has
a significant rigidity.
The presenee of an inner core in the Earth is revealed from
observations of the seismie pliase PKP in the « sliadow zone » for
which the epicentral distance A lies in the range 105" < A < 143".
Miss I. Lehmann (r in 1936, followed by Gutenberg and Richter (2
in 1938, atlrihuted these observations to tlie presence of an inner
core; and Jeffreys (3 in 1939 applied Airy's theory of diffraetion
near a caustic to sliow that the alternative theory of diffraetion
round the outer boundary of the centrai core was not capable of
explaining tlie observations in the shadow zone. The existence of the
inner core has been fairly generallv accepted sinee tliis ealculation
of Jeffreys.
Fluctuations and rigidities in local labor markets. Part 2: reinterpreting contracts
G L Clark
1983-01-01
Local labor markets are characterized by rigidities in their patterns of adjustment to short-run fluctuations. With or without unions, fluctuations in employment, hours worked, and money wages are unlike the patterns predicted by conventional discrete-exchange labor-market theories. Moreover there are distinct geographical and industrial patterns in the observed rigidities. Neoclassical implicit contract theory has been vindicated. Or has it? Obvious empirical difficulties remain, especially ...
Rahimi, Bahlol; Timpka, Toomas; Vimarlund, Vivian; Uppugunduri, Srinivas; Svensson, Mikael
2009-12-31
Computerized provider order entry (CPOE) systems have been introduced to reduce medication errors, increase safety, improve work-flow efficiency, and increase medical service quality at the moment of prescription. Making the impact of CPOE systems more observable may facilitate their adoption by users. We set out to examine factors associated with the adoption of a CPOE system for inter-organizational and intra-organizational care. The diffusion of innovation theory was used to understand physicians' and nurses' attitudes and thoughts about implementation and use of the CPOE system. Two online survey questionnaires were distributed to all physicians and nurses using a CPOE system in county-wide healthcare organizations. The number of complete questionnaires analyzed was 134 from 200 nurses (67.0%) and 176 from 741 physicians (23.8%). Data were analyzed using descriptive-analytical statistical methods. More nurses (56.7%) than physicians (31.3%) stated that the CPOE system introduction had worked well in their clinical setting (P system not adapted to their specific professional practice (P = system (P = 0.041). We found that in particular the received relative advantages of the CPOE system were estimated to be significantly (P systems are introduced as a response to the present limitations in paper-based systems. In consequence, user expectations are often high on their relative advantages as well as on a low level of complexity. Building CPOE systems therefore requires designs that can provide rather important additional advantages, e.g. by preventing prescription errors and ultimately improving patient safety and safety of clinical work. The decision-making process leading to the implementation and use of CPOE systems in healthcare therefore has to be improved. As any change in health service settings usually faces resistance, we emphasize that CPOE system designers and healthcare decision-makers should continually collect users' feedback about the systems, while
Superplastic flow of two-phase ceramics containing rigid inclusions-zirconia/mullite composites
International Nuclear Information System (INIS)
Yoon, C.K.; Chen, I.W.
1990-01-01
A continuum theory for non-newtonian flow of a two-phase composite containing rigid inclusions is presented. It predicts flow suppression by a factor of (1 - V) q , where V is the volume fraction of the rigid inclusion and q depends on the stress exponent and the inclusion shape. Stress concentrations in the rigid inclusion have also been evaluated. As the stress exponent increases, flow suppression is more pronounced even though stress concentration is less severe. To test this theory, superplastic flow of zirconia/mullite composites, in which zirconia is a soft, non-Newtonian super-plastic matrix and mullite is a rigid phase of various size, shape, and amount, is studied. The continuum theory is found to describe the two-phase superplastic flow reasonably well
Topology-Preserving Rigid Transformation of 2D Digital Images.
Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues
2014-02-01
We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping.
Vertebral Column Resection for Rigid Spinal Deformity.
Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G
2017-05-01
Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.
Vortex statistics for turbulence in a container with rigid boundaries
DEFF Research Database (Denmark)
Clercx, H.J.H.; Nielsen, A.H.
2000-01-01
The evolution of vortex statistics for decaying two-dimensional turbulence in a square container with rigid no-slip walls is compared with a few available experimental results and with the scaling theory of two-dimensional turbulent decay as proposed by Carnevale et al. Power-law exponents......, computed from an ensemble average of several numerical runs, coincide with some experimentally obtained values, but not with data obtained from numerical simulations of decaying two-dimensional turbulence with periodic boundary conditions....
Experimental consequences of predicted charge rigidity of superconductors
Energy Technology Data Exchange (ETDEWEB)
Hirsch, J.E., E-mail: jhirsch@ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 (United States)
2012-08-15
The theory of hole superconductivity predicts that in superconductors the charged superfluid is about a million times more rigid than the normal electron fluid. We point out that this physics should give rise to large changes in the bulk and surface plasmon dispersion relations of metals entering the superconducting state, that have not yet been experimentally detected and would be in stark contradiction with the expected behavior within conventional BCS-London theory. We also propose that this explains the puzzling experimental observations of Avramenko et al. on electron sound propagation in superconductors and the puzzling experiments of de Heer et al. detecting large electric dipole moments in small metal clusters, as well as the Tao effect on aggregation of superconducting microparticles in an electric field. Associated with the enhanced charge rigidity is a large increase in the electric screening length of superconductors at low temperatures that has not yet been experimentally detected. The physical origin of the enhanced charge rigidity and its relation to other aspects of the theory of hole superconductivity is discussed.
Heinemann, Alison; Mallis, Jackie
The document presents Module 4, applications of theories of creativity to the gifted/talented, of the Star Power modules developed for school personnel who have an interest in or a need to explore the area of gifted and talented education. It is explained in an introductory section that the modules can be used for independent study, for small…
Heinemann, Alison; Mallis, Jackie
The document presents Module 3, applications of theories of intelligence to the gifted/talented, of the Star Power modules developed for school personnel who have an interest in or a need to explore the area of gifted and talented education. It is explained in an introductory section that the modules can be used for independent study, for small…
Dynamical analysis of an orbiting three-rigid-body system
Energy Technology Data Exchange (ETDEWEB)
Pagnozzi, Daniele, E-mail: daniele.pagnozzi@strath.ac.uk, E-mail: james.biggs@strath.ac.uk; Biggs, James D., E-mail: daniele.pagnozzi@strath.ac.uk, E-mail: james.biggs@strath.ac.uk [Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow, Scotland (United Kingdom)
2014-12-10
The development of multi-joint-spacecraft mission concepts calls for a deeper understanding of their nonlinear dynamics to inform and enhance system design. This paper presents a study of a three-finite-shape rigid-body system under the action of an ideal central gravitational field. The aim of this paper is to gain an insight into the natural dynamics of this system. The Hamiltonian dynamics is derived and used to identify relative attitude equilibria of the system with respect to the orbital reference frame. Then a numerical investigation of the behaviour far from the equilibria is provided using tools from modern dynamical systems theory such as energy methods, phase portraits and Poincarè maps. Results reveal a complex structure of the dynamics as well as the existence of connections between some of the equilibria. Stable equilibrium configurations appear to be surrounded by very narrow regions of regular and quasi-regular motions. Trajectories evolve on chaotic motions in the rest of the domain.
On the surprising rigidity of the Pauli exclusion principle
International Nuclear Information System (INIS)
Greenberg, O.W.
1989-01-01
I review recent attempts to construct a local quantum field theory of small violations of the Pauli exclusion principle and suggest a qualitative reason for the surprising rigidity of the Pauli principle. I suggest that small violations can occur in our four-dimensional world as a consequence of the compactification of a higher-dimensional theory in which the exclusion principle is exactly valid. I briefly mention a recent experiment which places a severe limit on possible violations of the exclusion principle. (orig.)
On real structures on rigid surfaces
International Nuclear Information System (INIS)
Kulikov, Vik S; Kharlamov, V M
2002-01-01
We construct examples of rigid surfaces (that is, surfaces whose deformation class consists of a unique surface) with a particular behaviour with respect to real structures. In one example the surface has no real structure. In another it has a unique real structure, which is not maximal with respect to the Smith-Thom inequality. These examples give negative answers to the following problems: the existence of real surfaces in each deformation class of complex surfaces, and the existence of maximal real surfaces in every complex deformation class that contains real surfaces. Moreover, we prove that there are no real surfaces among surfaces of general type with p g =q=0 and K 2 =9. These surfaces also provide new counterexamples to the 'Dif = Def' problem
On real structures on rigid surfaces
Energy Technology Data Exchange (ETDEWEB)
Kulikov, Vik S [Steklov Mathematical Institute, Russian Academy of Sciences (Russian Federation); Kharlamov, V M [Institut de Recherche Matematique Avanee Universite Louis Pasteur et CNRS 7 rue Rene Descartes (France)
2002-02-28
We construct examples of rigid surfaces (that is, surfaces whose deformation class consists of a unique surface) with a particular behaviour with respect to real structures. In one example the surface has no real structure. In another it has a unique real structure, which is not maximal with respect to the Smith-Thom inequality. These examples give negative answers to the following problems: the existence of real surfaces in each deformation class of complex surfaces, and the existence of maximal real surfaces in every complex deformation class that contains real surfaces. Moreover, we prove that there are no real surfaces among surfaces of general type with p{sub g}=q=0 and K{sup 2}=9. These surfaces also provide new counterexamples to the 'Dif = Def' problem.
Psychological prices of branded foods and price rigidity : evidence from German scanner data
Herrmann, Roland; Möser, Anke
2004-01-01
There is increasing evidence from scanner data that branded foods in the grocery retailing sector contain a substantial amount of price rigidity (HERRMANN/MÖSER 2003). One of the many alternative explanations for price rigidity is the existence of psychological pricing points. The economic literature has been most hesitant against this theory and, in a survey, BLINDER et al. (1998) found no confirmation at all based on the views of business managers. In that study, however, retail trade is un...
Tidal Evolution of Asteroidal Binaries. Ruled by Viscosity. Ignorant of Rigidity.
Efroimsky, Michael
2015-10-01
This is a pilot paper serving as a launching pad for study of orbital and spin evolution of binary asteroids. The rate of tidal evolution of asteroidal binaries is defined by the dynamical Love numbers kl divided by quality factors Q. Common in the literature is the (oftentimes illegitimate) approximation of the dynamical Love numbers with their static counterparts. Since the static Love numbers are, approximately, proportional to the inverse rigidity, this renders a popular fallacy that the tidal evolution rate is determined by the product of the rigidity by the quality factor: {k}l/Q\\propto 1/(μ Q). In reality, the dynamical Love numbers depend on the tidal frequency and all rheological parameters of the tidally perturbed body (not just rigidity). We demonstrate that in asteroidal binaries the rigidity of their components plays virtually no role in tidal friction and tidal lagging, and thereby has almost no influence on the intensity of tidal interactions (tidal torques, tidal dissipation, tidally induced changes of the orbit). A key quantity that overwhelmingly determines the tidal evolution is a product of the effective viscosity η by the tidal frequency χ . The functional form of the torque’s dependence on this product depends on who wins in the competition between viscosity and self-gravitation. Hence a quantitative criterion, to distinguish between two regimes. For higher values of η χ , we get {k}l/Q\\propto 1/(η χ ), {while} for lower values we obtain {k}l/Q\\propto η χ . Our study rests on an assumption that asteroids can be treated as Maxwell bodies. Applicable to rigid rocks at low frequencies, this approximation is used here also for rubble piles, due to the lack of a better model. In the future, as we learn more about mechanics of granular mixtures in a weak gravity field, we may have to amend the tidal theory with other rheological parameters, ones that do not show up in the description of viscoelastic bodies. This line of study provides
Howarth, Michelle; Warne, Tony; Haigh, Carol
2012-11-01
Chronic back pain is a global phenomenon and a common reason why patients seek help from health professionals. Person-centered interprofessional working is acknowledged as the main strategy for chronic back pain management; however, the complexity of chronic pain can present significant challenges for teams. Although methods used by interprofessional teams to collaborate have been previously explored, how they work together to deliver person-centered chronic back pain care has received limited attention. The aim of this study was to explore person-centered care from the perspectives of people with chronic back pain and the interprofessional teams who cared for them. A grounded theory methodology was used to capture the interprofessional team's perspectives of person-centered working. A purposive sample of four chronic back pain management teams participated in semi-structured face-to-face interviews and focus groups. Data were thematically analyzed using a constant comparative method. Three categories emerged, collective efficacy, negotiated space and team maturity, which illustrated the attributes of interprofessional teams that influenced person-centered working. The findings suggest that collective efficacy matures over time within a negotiated coalesced space and re-enforces the need for teams to stick together to ensure effective person-centered care.
Mellis, Alexandra M; Snider, Sarah E; Bickel, Warren K
2018-04-01
Reading experimenter-provided narratives of negative income shock has been previously demonstrated to increase impulsivity, as measured by discounting of delayed rewards. We hypothesized that writing these narratives would potentiate their effects of negative income shock on decision-making more than simply reading them. In the current study, 193 cigarette-smoking individuals from Amazon Mechanical Turk were assigned to either read an experimenter-provided narrative or self-generate a narrative describing either the negative income shock of job loss or a neutral condition of job transfer. Individuals then completed a task of delay discounting and measures of affective response to narratives, as well as rating various narrative qualities such as personal relevance and vividness. Consistent with past research, narratives of negative income shock increased delay discounting compared to control narratives. No significant differences existed in delay discounting after self-generating compared to reading experimenter-provided narratives. Positive affect was lower and negative affect was higher in response to narratives of job loss, but affect measures did not differ based on whether narratives were experimenter-provided or self-generated. All narratives were rated as equally realistic, but self-generated narratives (whether negative or neutral) were rated as more vivid and relevant than experimenter-provided narratives. These results indicate that the content of negative income shock narratives, regardless of source, consistently drives short-term choices. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Equilibrium stability of strained epitaxial layers on a rigid substrate
International Nuclear Information System (INIS)
Granato, E.; Kosterlitz, J.M.; Ying, S.C.
1987-07-01
A simple theory of the equilibrium stability of an strained epitaxial layer on a rigid substrate is presented. We generalise the Frankvan der Merwe model of a single layer and consider N layers of adsorbate on a substrate. Continuum elasticity theory is used to describe each layer, but the coupling between layers is treated ina discrete fashion. Our method interpolates between a few layers and the thick film limit of standard dislocation theory, and in this limit the standard results are obtained. In addition, we developed a variational approach which agrees well with our exact calculations. The advantage of our method over previous ores is that it allows to perform stability analyses of arbitrary superlattice configurations. (author) [pt
A geometrical introduction to screw theory
International Nuclear Information System (INIS)
Minguzzi, E
2013-01-01
This work introduces screw theory, a venerable but little known theory aimed at describing rigid body dynamics. This formulation of mechanics unifies in the concept of screw the translational and rotational degrees of freedom of the body. It captures a remarkable mathematical analogy between mechanical momenta and linear velocities, and between forces and angular velocities. For instance, it clarifies that angular velocities should be treated as applied vectors and that, under the composition of motions, they sum with the same rules of applied forces. This work provides a short and rigorous introduction to screw theory intended for an undergraduate and general readership. (paper)
Analysis of Switched-Rigid Floating Oscillator
Directory of Open Access Journals (Sweden)
Prabhakar R. Marur
2009-01-01
Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.
Rigid pricing and rationally inattentive consumer
Czech Academy of Sciences Publication Activity Database
Matějka, Filip
158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: PRVOUK-P23 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015
Rigid pricing and rationally inattentive consumer
Czech Academy of Sciences Publication Activity Database
Matějka, Filip
158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: RVO:67985998 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015
Soft soils reinforced by rigid vertical inclusions
Directory of Open Access Journals (Sweden)
Iulia-Victoria NEAGOE
2013-12-01
Full Text Available Reinforcement of soft soils by rigid vertical inclusions is an increasingly used technique over the last few years. The system consists of rigid or semi-rigid vertical inclusions and a granular platform for the loads transfer from the structure to the inclusions. This technique aims to reduce the differential settlements both at ground level as below the structure. Reinforcement by rigid inclusions is mainly used for foundation works for large commercial and industrial platforms, storage tanks, wastewater treatment plants, wind farms, bridges, roads, railway embankments. The subject is one of interest as it proves the recently concerns at international level in research and design; however, most studies deal more with the static behavior and less with the dynamic one.
Microstructural Dynamics and Rheology of Suspensions of Rigid Fibers
Butler, Jason E.; Snook, Braden
2018-01-01
The dynamics and rheology of suspensions of rigid, non-Brownian fibers in Newtonian fluids are reviewed. Experiments, theories, and computer simulations are considered, with an emphasis on suspensions at semidilute and concentrated conditions. In these suspensions, interactions between the particles strongly influence the microstructure and rheological properties of the suspension. The interactions can arise from hydrodynamic disturbances, giving multibody interactions at long ranges and pairwise lubrication forces over short distances. For concentrated suspensions, additional interactions due to excluded volume (contacts) and adhesive forces are addressed. The relative importance of the various interactions as a function of fiber concentration is assessed.
Directory of Open Access Journals (Sweden)
Svetoslav Ganchev Nikolov
2015-07-01
Full Text Available The study of the dynamic behavior of a rigid body with one fixed point (gyroscope has a long history. A number of famous mathematicians and mechanical engineers have devoted enormous time and effort to clarify the role of dynamic effects on its movement (behavior – stable, periodic, quasi-periodic or chaotic. The main objectives of this review are: 1 to outline the characteristic features of the theory of dynamical systems and 2 to reveal the specific properties of the motion of a rigid body with one fixed point (gyroscope.This article consists of six sections. The first section addresses the main concepts of the theory of dynamical systems. Section two presents the main theoretical results (obtained so far concerning the dynamic behavior of a solid with one fixed point (gyroscope. Section three examines the problem of gyroscopic stabilization. Section four deals with the non-linear (chaotic dynamics of the gyroscope. Section five is a brief analysis of the gyroscope applications in engineering. The final section provides conclusions and generalizations on why the theory of dynamical systems should be used in the study of the movement of gyroscopic systems.
Flexible and rigid cystoscopy in women.
Gee, Jason R; Waterman, Bradley J; Jarrard, David F; Hedican, Sean P; Bruskewitz, Reginald C; Nakada, Stephen Y
2009-01-01
Previous studies have evaluated the tolerability of rigid versus flexible cystoscopy in men. Similar studies, however, have not been performed in women. We sought to determine whether office-based flexible cystoscopy was better tolerated than rigid cystoscopy in women. Following full IRB approval, women were prospectively randomized in a single-blind manner. Patients were randomized to flexible or rigid cystoscopy and draped in the lithotomy position to maintain blinding of the study. Questionnaires evaluated discomfort before, during, and after cystoscopy. Thirty-six women were randomized to flexible (18) or rigid (18) cystoscopy. Indications were surveillance (16), hematuria (15), recurrent UTIs (2), voiding dysfunction (1), and other (2). All questionnaires were returned by 31/36 women. Using a 10-point visual analog scale (VAS), median discomfort during the procedure for flexible and rigid cystoscopy were 1.4 and 1.8, respectively, in patients perceiving pain. Median recalled pain 1 week later was similar at 0.8 and 1.15, respectively. None of these differences were statistically significant. Flexible and rigid cystoscopy are well tolerated in women. Discomfort during and after the procedure is minimal in both groups. Urologists should perform either procedure in women based on their preference and skill level.
Multiscale multiphysics and multidomain models—Flexibility and rigidity
International Nuclear Information System (INIS)
Xia, Kelin; Opron, Kristopher; Wei, Guo-Wei
2013-01-01
The emerging complexity of large macromolecules has led to challenges in their full scale theoretical description and computer simulation. Multiscale multiphysics and multidomain models have been introduced to reduce the number of degrees of freedom while maintaining modeling accuracy and achieving computational efficiency. A total energy functional is constructed to put energies for polar and nonpolar solvation, chemical potential, fluid flow, molecular mechanics, and elastic dynamics on an equal footing. The variational principle is utilized to derive coupled governing equations for the above mentioned multiphysical descriptions. Among these governing equations is the Poisson-Boltzmann equation which describes continuum electrostatics with atomic charges. The present work introduces the theory of continuum elasticity with atomic rigidity (CEWAR). The essence of CEWAR is to formulate the shear modulus as a continuous function of atomic rigidity. As a result, the dynamics complexity of a macromolecular system is separated from its static complexity so that the more time-consuming dynamics is handled with continuum elasticity theory, while the less time-consuming static analysis is pursued with atomic approaches. We propose a simple method, flexibility-rigidity index (FRI), to analyze macromolecular flexibility and rigidity in atomic detail. The construction of FRI relies on the fundamental assumption that protein functions, such as flexibility, rigidity, and energy, are entirely determined by the structure of the protein and its environment, although the structure is in turn determined by all the interactions. As such, the FRI measures the topological connectivity of protein atoms or residues and characterizes the geometric compactness of the protein structure. As a consequence, the FRI does not resort to the interaction Hamiltonian and bypasses matrix diagonalization, which underpins most other flexibility analysis methods. FRI's computational complexity is of O
Multibody Dynamic Stress Simulation of Rigid-Flexible Shovel Crawler Shoes
Directory of Open Access Journals (Sweden)
Samuel Frimpong
2016-06-01
Full Text Available Electric shovels are used in surface mining operations to achieve economic production capacities. The capital investments and operating costs associated with the shovels deployed in the Athabasca oil sands formation are high due to the abrasive conditions. The shovel crawler shoes interact with sharp and abrasive sand particles, and, thus, are subjected to high transient dynamic stresses. These high stresses cause wear and tear leading to crack initiation, propagation and premature fatigue failure. The objective of this paper is to develop a model to characterize the crawler stresses and deformation for the P&H 4100C BOSS during propel and loading using rigid-flexible multi-body dynamic theory. A 3-D virtual prototype model of the rigid-flexible crawler track assembly and its interactions with oil sand formation is simulated to capture the model dynamics within multibody dynamics software MSC ADAMS. The modal and stress shapes and modal loads due to machine weight for each flexible crawler shoes are generated from finite element analysis (FEA. The modal coordinates from the simulation are combined with mode and stress shapes using modal superposition method to calculate real-time stresses and deformation of flexible crawler shoes. The results show a maximum von Mises stress value of 170 MPa occurring in the driving crawler shoe during the propel motion. This study provides a foundation for the subsequent fatigue life analysis of crawler shoes for extending crawler service life.
Initial Development of an Electronic Testis Rigidity Tester
Directory of Open Access Journals (Sweden)
Petros Mirilas
2011-01-01
Full Text Available We aimed to develop our previously presented mechanical device, the Testis Rigidity Tester (TRT, into an electronic system (Electronic Testis Rigidity Tester, ETRT by applying tactile imaging, which has been used successfully with other solid organs. A measuring device, located at the front end of the ETRT incorporates a tactile sensor comprising an array of microsensors. By application of a predetermined deformation of 2 mm, increased pressure alters linearly the resistance of each microsensor, producing changes of voltage. These signals were amplified, filtered, and digitized, and then processed by an electronic collector system, which presented them as a color-filled contour plot of the area of the testis coming into contact with the sensor. Testis models of different rigidity served for initial evaluation of ETRT; their evacuated central spaces contained different, increasing glue masses. An independent method of rigidity measurement, using an electric weight scale and a micrometer, showed that the more the glue injected, the greater the force needed for a 2-mm deformation. In a preliminary test, a single sensor connected to a multimeter showed similar force measurement for the same deformation in these phantoms. For each of the testis models compressed in the same manner, the ETRT system offered a map of pressures, represented by a color scale within the contour plot of the contact area with the sensor. ETRT found certain differences in rigidity between models that had escaped detection by a blind observer. ETRT is easy to use and provides a color-coded “insight“ of the testis internal structure. After experimental testing, it could be valuable in intraoperative evaluation of testes, so that the surgeon can decide about orchectomy or orcheopexy.
Rigid Body Sampling and Individual Time Stepping for Rigid-Fluid Coupling of Fluid Simulation
Directory of Open Access Journals (Sweden)
Xiaokun Wang
2017-01-01
Full Text Available In this paper, we propose an efficient and simple rigid-fluid coupling scheme with scientific programming algorithms for particle-based fluid simulation and three-dimensional visualization. Our approach samples the surface of rigid bodies with boundary particles that interact with fluids. It contains two procedures, that is, surface sampling and sampling relaxation, which insures uniform distribution of particles with less iterations. Furthermore, we present a rigid-fluid coupling scheme integrating individual time stepping to rigid-fluid coupling, which gains an obvious speedup compared to previous method. The experimental results demonstrate the effectiveness of our approach.
Roberto, Anthony J; Shafer, Michael S; Marmo, Jennifer
2014-01-01
The purpose of this investigation is to determine if the theory of reasoned action (TRA) and theory of planned behavior (TPB) can retrospectively predict whether substance-abuse treatment providers encourage their clients to use medicated-assisted treatment (MAT) as part of their treatment plan. Two-hundred and ten substance-abuse treatment providers completed a survey measuring attitudes, subjective norms, perceived behavioral control, intentions, and behavior. Results indicate that substance-abuse treatment providers have very positive attitudes, neutral subjective norms, somewhat positive perceived behavioral control, somewhat positive intentions toward recommending MAT as part of their clients' treatment plan, and were somewhat likely to engage in the actual behavior. Further, the data fit both the TRA and TPB, but with the TPB model having better fit and predictive power for this target audience and behavior. The theoretical and practical implications for the developing messages for substance-abuse treatment providers and other health-care professionals who provide treatment to patients with substance use disorders are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.
Gangadharan, Sandeep; Tiyyagura, Gunjan; Gawel, Marcie; Walsh, Barbara M; Brown, Linda L; Lavoie, Megan; Tay, Khoon-Yen; Auerbach, Marc A
2016-10-04
The objective of this study was to explore pediatric emergency department (PED) and general emergency department (GED) providers' perceptions on caring for critically ill infants and children. This study utilized qualitative methods to examine the perceptions of emergency department providers caring for critically ill infants and children. Teams of providers participated in 4 in situ simulation cases followed by facilitated debriefings. Debriefings were recorded and professionally transcribed. The transcripts were reviewed independently and followed by group coding discussions to identify emerging themes. Consistent with grounded theory, the team iteratively revised the debriefing script as new understanding was gained. A total of 188 simulation debriefings were recorded in 24 departments, with 15 teams participating from 8 PEDs and 32 teams from 16 GEDs. Twenty-four debriefings were audiotaped and professionally transcribed verbatim. Thematic saturation was achieved after 20 transcripts. In our iterative qualitative analysis of these transcripts, we observed 4 themes: (1) GED provider comfort with algorithm-based pediatric care and overall comfort with pediatric care in PED, (2) GED provider reliance on cognitive aids versus experience-based recall by PED providers, (3) GED provider discomfort with locating and determining size or dose of pediatric-specific equipment and medications, and (4) PED provider reliance on larger team size and challenges with multitasking during resuscitation. Our qualitative analysis produced several themes that help us to understand providers' perceptions in caring for critically ill children in GEDs and PEDs. These data could guide the development of targeted educational and improvement interventions.
Nanjappa, S; Chambers, S; Marcenes, W; Richards, D; Freeman, R
2014-10-01
A theory-led narrative approach was used to unpack the complexities of the factors that enable successful client adherence following one-to-one health interventions. Understanding this could prepare the provider to anticipate different adherence behaviours by clients, allowing them to tailor their interventions to increase the likelihood of adherence. The review was done in two stages. A theoretical formulation was proposed to explore factors which influence the effectiveness of one-to-one interventions to result in client adherence. The second stage tested this theory using a narrative synthesis approach. Eleven studies across the health care arena were included in the synthesis and explored the interplay between client attachment style, client-provider interaction and client adherence with health interventions. It emerged that adherence results substantially because of the relationship that the client has with the provider, which is amplified or diminished by the client's own attachment style. This occurs because the client's attachment style shapes how they perceive and behave in relationships with the health-care providers, who become the 'secure base' from which the client accepts, assimilates and adheres with the recommended health intervention. The pathway from one-to-one interventions to adherence is explained using moderated mediation and mediated moderation models. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.
Identifying Floppy and Rigid Regions in Proteins
Jacobs, D. J.; Thorpe, M. F.; Kuhn, L. A.
1998-03-01
In proteins it is possible to separate hard covalent forces involving bond lengths and bond angles from other weak forces. We model the microstructure of the protein as a generic bar-joint truss framework, where the hard covalent forces and strong hydrogen bonds are regarded as rigid bar constraints. We study the mechanical stability of proteins using FIRST (Floppy Inclusions and Rigid Substructure Topography) based on a recently developed combinatorial constraint counting algorithm (the 3D Pebble Game), which is a generalization of the 2D pebble game (D. J. Jacobs and M. F. Thorpe, ``Generic Rigidity: The Pebble Game'', Phys. Rev. Lett.) 75, 4051-4054 (1995) for the special class of bond-bending networks (D. J. Jacobs, "Generic Rigidity in Three Dimensional Bond-bending Networks", Preprint Aug (1997)). This approach is useful in identifying rigid motifs and flexible linkages in proteins, and thereby determines the essential degrees of freedom. We will show some preliminary results from the FIRST analysis on the myohemerythrin and lyozyme proteins.
Slip Morphology of Elastic Strips on Frictional Rigid Substrates.
Sano, Tomohiko G; Yamaguchi, Tetsuo; Wada, Hirofumi
2017-04-28
The morphology of an elastic strip subject to vertical compressive stress on a frictional rigid substrate is investigated by a combination of theory and experiment. We find a rich variety of morphologies, which-when the bending elasticity dominates over the effect of gravity-are classified into three distinct types of states: pinned, partially slipped, and completely slipped, depending on the magnitude of the vertical strain and the coefficient of static friction. We develop a theory of elastica under mixed clamped-hinged boundary conditions combined with the Coulomb-Amontons friction law and find excellent quantitative agreement with simulations and controlled physical experiments. We also discuss the effect of gravity in order to bridge the difference in the qualitative behaviors of stiff strips and flexible strings or ropes. Our study thus complements recent work on elastic rope coiling and takes a significant step towards establishing a unified understanding of how a thin elastic object interacts vertically with a solid surface.
Quantum mechanics of a generalised rigid body
International Nuclear Information System (INIS)
Gripaios, Ben; Sutherland, Dave
2016-01-01
We consider the quantum version of Arnold’s generalisation of a rigid body in classical mechanics. Thus, we quantise the motion on an arbitrary Lie group manifold of a particle whose classical trajectories correspond to the geodesics of any one-sided-invariant metric. We show how the derivation of the spectrum of energy eigenstates can be simplified by making use of automorphisms of the Lie algebra and (for groups of type I) by methods of harmonic analysis. We show how the method can be extended to cosets, generalising the linear rigid rotor. As examples, we consider all connected and simply connected Lie groups up to dimension 3. This includes the universal cover of the archetypical rigid body, along with a number of new exactly solvable models. We also discuss a possible application to the topical problem of quantising a perfect fluid. (paper)
Durable bistable auxetics made of rigid solids
Shang, Xiao; Liu, Lu; Rafsanjani, Ahmad; Pasini, Damiano
2018-02-01
Bistable Auxetic Metamaterials (BAMs) are a class of monolithic perforated periodic structures with negative Poisson's ratio. Under tension, a BAM can expand and reach a second state of equilibrium through a globally large shape transformation that is ensured by the flexibility of its elastomeric base material. However, if made from a rigid polymer, or metal, BAM ceases to function due to the inevitable rupture of its ligaments. The goal of this work is to extend the unique functionality of the original kirigami architecture of BAM to a rigid solid base material. We use experiments and numerical simulations to assess performance, bistability and durability of rigid BAMs at 10,000 cycles. Geometric maps are presented to elucidate the role of the main descriptors of BAM architecture. The proposed design enables the realization of BAM from a large palette of materials, including elastic-perfectly plastic materials and potentially brittle materials.
Type number and rigidity of fibred surfaces
International Nuclear Information System (INIS)
Markov, P E
2001-01-01
Infinitesimal l-th order bendings, 1≤l≤∞, of higher-dimensional surfaces are considered in higher-dimensional flat spaces (for l=∞ an infinitesimal bending is assumed to be an analytic bending). In terms of the Allendoerfer type number, criteria are established for the (r,l)-rigidity (in the terminology of Sabitov) of such surfaces. In particular, an (r,l)-infinitesimal analogue is proved of the classical theorem of Allendoerfer on the unbendability of surfaces with type number ≥3 and the class of (r,l)-rigid fibred surfaces is distinguished
Rigid origami vertices: conditions and forcing sets
Directory of Open Access Journals (Sweden)
Zachary Abel
2016-04-01
Full Text Available We develop an intrinsic necessary and sufficient condition for single-vertex origami crease patterns to be able to fold rigidly. We classify such patterns in the case where the creases are pre-assigned to be mountains and valleys as well as in the unassigned case. We also illustrate the utility of this result by applying it to the new concept of minimal forcing sets for rigid origami models, which are the smallest collection of creases that, when folded, will force all the other creases to fold in a prescribed way.
Evaluating a method for automated rigid registration
DEFF Research Database (Denmark)
Darkner, Sune; Vester-Christensen, Martin; Larsen, Rasmus
2007-01-01
to point distance. T-test for common mean are used to determine the performance of the two methods (supported by a Wilcoxon signed rank test). The performance influence of sampling density, sampling quantity, and norms is analyzed using a similar method.......We evaluate a novel method for fully automated rigid registration of 2D manifolds in 3D space based on distance maps, the Gibbs sampler and Iterated Conditional Modes (ICM). The method is tested against the ICP considered as the gold standard for automated rigid registration. Furthermore...
Butler, Ashleigh E; Copnell, Beverley; Hall, Helen
2017-12-30
This study explores the influences of the paediatric intensive care environment on relationships between parents and healthcare providers when children are dying. It forms part of a larger study, investigating parental experiences of the death of their child in intensive care. Constructivist grounded theory. Four Australian paediatric intensive care units. Audio-recorded, semi-structured interviews were conducted with twenty-six bereaved parents. Data were analysed using the constant comparison and memoing techniques common to grounded theory. The physical and social environment of the intensive care unit influenced the quality of the parent-healthcare provider relationship. When a welcoming, open environment existed, parents tended to feel respected as equal and included members of their child's care team. In contrast, environments that restricted parental presence or lacked resources for parental self-care could leave parents feeling like 'watchers', excluded from their child's care. The paediatric intensive care unit environment either welcomes and includes parents of dying children into the care team, or demotes them to the status of 'watcher'. Such environments significantly influence the relationships parents form with healthcare staff, their ability to engage in elements of their parental role, and their experiences as a whole. Copyright © 2017 Elsevier Ltd. All rights reserved.
Geometric integrators for stochastic rigid body dynamics
Tretyakov, Mikhail
2016-01-05
Geometric integrators play an important role in simulating dynamical systems on long time intervals with high accuracy. We will illustrate geometric integration ideas within the stochastic context, mostly on examples of stochastic thermostats for rigid body dynamics. The talk will be mainly based on joint recent work with Rusland Davidchak and Tom Ouldridge.
Combinatorial and Algorithmic Rigidity: Beyond Two Dimensions
2012-12-01
44]. Theorems of Maxwell- Laman type were ob- tained in [9, 15, 43]. 2 3. Counting and Enumeration. As anticipated in the project, we relied on methods...decompositions. Graphs and Combinatorics, 25:219–238, 2009. [43] I. Streinu and L. Theran. Slider-pinning rigidity: a Maxwell- Laman -type theorem. Discrete and
Geometric integrators for stochastic rigid body dynamics
Tretyakov, Mikhail
2016-01-01
Geometric integrators play an important role in simulating dynamical systems on long time intervals with high accuracy. We will illustrate geometric integration ideas within the stochastic context, mostly on examples of stochastic thermostats for rigid body dynamics. The talk will be mainly based on joint recent work with Rusland Davidchak and Tom Ouldridge.
About deformation and rigidity in relativity
International Nuclear Information System (INIS)
Coll, Bartolome
2007-01-01
The notion of deformation involves that of rigidity. In relativity, starting from Born's early definition of rigidity, some other ones have been proposed, offering more or less interesting aspects but also accompanied of undesired or even pathological properties. In order to clarify the origin of these difficulties presented by the notion of rigidity in relativity, we analyze with some detail significant aspects of the unambiguous classical, Newtonian, notion. In particular, the relative character of its kinetic definition is pointed out, allowing to predict and to understand the limitations imposed by Herglotz-Noether theorem. Also, its equivalent dynamic definition is obtained and, in contrast, its absolute character is shown. But in spite of this absolute character, the dynamic definition is shown to be not extensible to relativity. The metric deformation of Minkowski space by the presence of a gravitational field is interpreted as a universal deformation, and it is shown that, under natural conditions, only a simple deformation law is possible, relating locally, but in an one-to-one way, gravitational fields and gauge classes of two-forms. We argue that fields of unit vectors associated to the internal gauge class of two-forms of every space-time (and, in particular, of Minkowski space-time) are the relativistic analogues of the classical accelerated observers, i.e. of the classical rigid motions. Some other consequences of the universal law of gravitational deformation are commented
Rigid pricing and rationally inattentive consumer
Czech Academy of Sciences Publication Activity Database
Matějka, Filip
2010-01-01
Roč. 20, č. 2 (2010), s. 1-40 ISSN 1211-3298 R&D Projects: GA MŠk LC542 Institutional research plan: CEZ:AV0Z70850503 Keywords : rational inattention * nominal rigidity Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp409.pdf
Cracking of open traffic rigid pavement
Directory of Open Access Journals (Sweden)
Niken Chatarina
2017-01-01
Full Text Available The research is done by observing the growth of real structure cracking in Natar, Lampung, Indonesia compared to C. Niken’s et al research and literature study. The rigid pavement was done with open traffic system. There are two main crack types on Natar rigid pavement: cracks cross the road, and cracks spreads on rigid pavement surface. The observation of cracks was analyzed by analyzing material, casting, curing, loading and shrinkage mechanism. The relationship between these analysis and shrinkage mechanism was studied in concrete micro structure. Open traffic make hydration process occur under vibration; therefore, fresh concrete was compressed and tensioned alternately since beginning. High temperature together with compression, cement dissociation, the growth of Ca2+ at very early age leads abnormal swelling. No prevention from outside water movement leads hydration process occur with limited water which caused spreads fine cracks. Limited water improves shrinkage and plastic phase becomes shorter; therefore, rigid pavement can’t accommodate the abnormal swelling and shrinking alternately and creates the spread of cracks. Discontinuing casting the concrete makes both mix under different condition, the first is shrink and the second is swell and creates weak line on the border; so, the cracks appear as cracks across the road.
Rigid Spine Syndrome among Children in Oman
Directory of Open Access Journals (Sweden)
Roshan Koul
2015-08-01
Full Text Available Objectives: Rigidity of the spine is common in adults but is rarely observed in children. The aim of this study was to report on rigid spine syndrome (RSS among children in Oman. Methods: Data on children diagnosed with RSS were collected consecutively at presentation between 1996 and 2014 at the Sultan Qaboos University Hospital (SQUH in Muscat, Oman. A diagnosis of RSS was based on the patient’s history, clinical examination, biochemical investigations, electrophysiological findings, neuro-imaging and muscle biopsy. Atrophy of the paraspinal muscles, particularly the erector spinae, was the diagnostic feature; this was noted using magnetic resonance imaging of the spine. Children with disease onset in the paraspinal muscles were labelled as having primary RSS or rigid spinal muscular dystrophy. Secondary RSS was classified as RSS due to the late involvement of other muscle diseases. Results: Over the 18-year period, 12 children were included in the study, with a maleto- female ratio of 9:3. A total of 10 children were found to have primary RSS or rigid spinal muscular dystrophy syndrome while two had secondary RSS. Onset of the disease ranged from birth to 18 months of age. A family history was noted, with two siblings from one family and three siblings from another (n = 5. On examination, children with primary RSS had typical features of severe spine rigidity at onset, with the rest of the neurological examination being normal. Conclusion: RSS is a rare disease with only 12 reported cases found at SQUH during the study period. Cases of primary RSS should be differentiated from the secondary type.
He, Yuan; Yang, Fan; Mu, Dongqin; Xing, Yuan; Li, Xin
2016-10-05
Main study aim was as follows: (1) to explore the usefulness of the theory of planned behaviour (TPB) model in predicting Chinese hospital pharmacists' intention to provide clinical pharmacy services (CPSs), including auxiliary CPSs and core CPSs; (2) to identify the main factors affecting the Chinese hospital pharmacists' intention to provide core CPSs based on TPB quantitatively. Cross-sectional questionnaire study. The study was conducted in 22 general hospitals in seven cities located in the eastern and western part of China. 416 hospital pharmacists (292 (70.2%) female) entered and completed the study. Quantitative responses with hospital pharmacists' intention, attitude, subjective norms (SNs) and perceived behavioural control (PBC) over provision of CPSs and their past behaviour (PB)-related CPSs. The structural equation model analysis found that attitude (p=0.0079, β=0.12), SN (p=0.038, β=0.10) and the pharmacists' intention to provide auxiliary CPSs (p=0.0001, β=0.63) significantly predicted of their intention to provide core CPSs, accounting for 54.0% of its variance. Attitude (p=0.0001, β=0.35), PBC (p=0.0182, β=0.12) and PB (p=0.0009, β=0.15) are significant predictors of pharmacists' intention, accounting for 21% of the variance in pharmacists' intention to provide auxiliary CPSs. The TPB with the addition of PB is a useful framework for predicting pharmacists' intention to provide CPSs in Chinese hospital care context. Strategies to improve hospital pharmacists' intention to provide CPSs should focus on helping the individuals related medical care see the value of CPSs, altering their perception of social pressure towards core CPSs and the removal of obstacles that impede the translation of intentions into behaviour. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
He, Yuan; Yang, Fan; Mu, Dongqin; Xing, Yuan; Li, Xin
2016-01-01
Objectives Main study aim was as follows: (1) to explore the usefulness of the theory of planned behaviour (TPB) model in predicting Chinese hospital pharmacists' intention to provide clinical pharmacy services (CPSs), including auxiliary CPSs and core CPSs; (2) to identify the main factors affecting the Chinese hospital pharmacists' intention to provide core CPSs based on TPB quantitatively. Design Cross-sectional questionnaire study. Setting The study was conducted in 22 general hospitals in seven cities located in the eastern and western part of China. Participants 416 hospital pharmacists (292 (70.2%) female) entered and completed the study. Primary and secondary outcome measures Quantitative responses with hospital pharmacists' intention, attitude, subjective norms (SNs) and perceived behavioural control (PBC) over provision of CPSs and their past behaviour (PB)-related CPSs. Results The structural equation model analysis found that attitude (p=0.0079, β=0.12), SN (p=0.038, β=0.10) and the pharmacists' intention to provide auxiliary CPSs (p=0.0001, β=0.63) significantly predicted of their intention to provide core CPSs, accounting for 54.0% of its variance. Attitude (p=0.0001, β=0.35), PBC (p=0.0182, β=0.12) and PB (p=0.0009, β=0.15) are significant predictors of pharmacists' intention, accounting for 21% of the variance in pharmacists' intention to provide auxiliary CPSs. Conclusions The TPB with the addition of PB is a useful framework for predicting pharmacists' intention to provide CPSs in Chinese hospital care context. Strategies to improve hospital pharmacists' intention to provide CPSs should focus on helping the individuals related medical care see the value of CPSs, altering their perception of social pressure towards core CPSs and the removal of obstacles that impede the translation of intentions into behaviour. PMID:27707835
The two-body problem of a pseudo-rigid body and a rigid sphere
DEFF Research Database (Denmark)
Kristiansen, Kristian Uldall; Vereshchagin, M.; Gózdziewski, K.
2012-01-01
n this paper we consider the two-body problem of a spherical pseudo-rigid body and a rigid sphere. Due to the rotational and "re-labelling" symmetries, the system is shown to possess conservation of angular momentum and circulation. We follow a reduction procedure similar to that undertaken...... in the study of the two-body problem of a rigid body and a sphere so that the computed reduced non-canonical Hamiltonian takes a similar form. We then consider relative equilibria and show that the notions of locally central and planar equilibria coincide. Finally, we show that Riemann's theorem on pseudo......-rigid bodies has an extension to this system for planar relative equilibria....
Biomimetic model systems of rigid hair beds: Part II - Experiment
Jammalamadaka, Mani S. S.; Hood, Kaitlyn; Hosoi, Anette
2017-11-01
Crustaceans - such as lobsters, crabs and stomapods - have hairy appendages that they use to recognize and track odorants in the surrounding fluid. An array of rigid hairs impedes flow at different rates depending on the spacing between hairs and the Reynolds number, Re. At larger Reynolds number (Re>1), fluid travels through the hairs rather than around them, a phenomenon called leakiness. Crustaceans flick their appendages at different speeds in order to manipulate the leakiness between the hairs, allowing the hairs to either detect the odors in a sample of fluid or collect a new sample. Theoretical and numerical studies predict that there is a fast flow region near the hairs that moves closer to the hairs as Re increases. Here, we test this theory experimentally. We 3D printed rigid hairs with an aspect ratio of 30:1 in rectangular arrays with different hair packing fractions. We custom built an experimental setup which establishes poiseuille flow at intermediate Re, Re <=200. We track the flow dynamics through the hair beds using tracer particles and Particle Imaging Velocimetry. We will then compare the modelling predictions with the experimental outcomes.
Collisions of Constrained Rigid Body Systems with Friction
Directory of Open Access Journals (Sweden)
Haijun Shen
1998-01-01
Full Text Available A new approach is developed for the general collision problem of two rigid body systems with constraints (e.g., articulated systems, such as massy linkages in which the relative tangential velocity at the point of contact and the associated friction force can change direction during the collision. This is beyond the framework of conventional methods, which can give significant and very obvious errors for this problem, and both extends and consolidates recent work. A new parameterization and theory characterize if, when and how the relative tangential velocity changes direction during contact. Elastic and dissipative phenomena and different values for static and kinetic friction coefficients are included. The method is based on the explicitly physical analysis of events at the point of contact. Using this method, Example 1 resolves (and corrects a paradox (in the literature of the collision of a double pendulum with the ground. The method fundamentally subsumes other recent models and the collision of rigid bodies; it yields the same results as conventional methods when they would apply (Example 2. The new method reformulates and extends recent approaches in a completely physical context.
Leece, Pamela; Buchman, Daniel Z; Hamilton, Michael; Timmings, Caitlyn; Shantharam, Yalnee; Moore, Julia; Furlan, Andrea D
2017-01-01
Introduction In North America, drug overdose deaths are reaching unprecedented levels, largely driven by increasing prescription opioid-related deaths. Despite the development of several opioid guidelines, prescribing behaviours still contribute to poor patient outcomes and societal harm. Factors at the provider and system level may hinder or facilitate the application of evidence-based guidelines; interventions designed to address such factors are needed. Methods and analysis Using implementation science and behaviour change theory, we have planned the development and evaluation of a comprehensive Opioid Self-Assessment Package, designed to increase adherence to the Canadian Opioid Guideline among family physicians. The intervention uses practical educational and self-assessment tools to provide prescribers with feedback on their current knowledge and practices, and resources to improve their practice. The evaluation approach uses a pretest and post-test design and includes both quantitative and qualitative methods at baseline and 6 months. We will recruit a purposive sample of approximately 10 family physicians in Ontario from diverse practice settings, who currently treat patients with long-term opioid therapy for chronic pain. Quantitative data will be analysed using basic descriptive statistics, and qualitative data will be analysed using the Framework Method. Ethics and dissemination The University Health Network Research Ethics Board approved this study. Dissemination plan includes publications, conference presentations and brief stakeholder reports. This evidence-informed, theory-driven intervention has implications for national application of opioid quality improvement tools in primary care settings. We are engaging experts and end users in advisory and stakeholder roles throughout our project to increase its national relevance, application and sustainability. The performance measures could be used as the basis for health system quality improvement
Three-dimensional formulation of rigid-flexible multibody systems with flexible beam elements
International Nuclear Information System (INIS)
Garcia-Vallejo, D.; Mayo, J.; Escalona, J. L.; Dominguez, J.
2008-01-01
Multibody systems generally contain solids with appreciable deformations and which decisively influence the dynamics of the system. These solids have to be modeled by means of special formulations for flexible solids. At the same time, other solids are of such a high stiffness that they may be considered rigid, which simplifies their modeling. For these reasons, for a rigid-flexible multibody system, two types of formulations coexist in the equations of the system. Among the different possibilities provided in the literature on the material, the formulation in natural coordinates and the formulation in absolute nodal coordinates are utilized in this paper to model the rigid and flexible solids, respectively. This paper contains a mixed formulation based on the possibility of sharing coordinates between a rigid solid and a flexible solid. The global mass matrix of the system is shown to be constant and, in addition, many of the constraint equations obtained upon utilizing these formulations are linear and can be eliminated
Financial Constraints and Nominal Price Rigidities
DEFF Research Database (Denmark)
Menno, Dominik Francesco; Balleer, Almut; Hristov, Nikolay
This paper investigates how financial market imperfections and the frequency of price adjustment interact. Based on new firm-level evidence for Germany, we document that financially constrained firms adjust prices more often than their unconstrained counterparts, both upwards and downwards. We show...... that these empirical patterns are consistent with a partial equilibrium menu-cost model with a working capital constraint. We then use the model to show how the presence of financial frictions changes profits and the price distribution of firms compared to a model without financial frictions. Our results suggest...... that tighter financial constraints are associated with higher nominal rigidities, higher prices and lower output. Moreover, in response to aggregate shocks, aggregate price rigidity moves substantially, the response of inflation is dampened, while output reacts more in the presence of financial frictions...
Rigidity of the magic pentagram game
Kalev, Amir; Miller, Carl A.
2018-01-01
A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.
Rigidity of the magic pentagram game.
Kalev, Amir; Miller, Carl A
2018-01-01
A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.
International Nuclear Information System (INIS)
Flueckiger, E.O.; Smart, D.F.; Shea, M.A.
1983-01-01
We have investigated the effect of local perturbations of the geomagnetic field on the vertical cosmic ray cutoff rigidities at Jungfraujoch and Kiel as representative mid-latitude neutron monitor stations. The main, effective, and Stoermer vertical cutoff rigidities and their changes were determined by utilizing the trajectory-tracing technique in a magnetic field which is modeled as a simple dipole field to which the disturbance field is superposed. It was found that the cosmic ray cutoff rigidities are most sensitive to variations of the z component of the geomagnetic field at geomagnetic latitudes -20 0 0 and at longitudes within 90 0 to the east of these northern hemisphere stations. Furthermore, cutoff rigidity variations at Kiel are predominantly due to changes of the geomagnetic field within geocentric distances 2.5R/sub E/< r<6R/sub E/, whereas at Jungfraujoch changes in cutoff rigidities are caused almost exclusively by magnetic disturbances within 1R/sub E/< r<4.5R/sub E/. For both locations the dependence of the main, effective, and Stoermer vertical cutoff rigidities on the radial, latitudinal and longitudinal structure of the magnetic perturbations is given explicitly. The results are discussed with respect to the theory by Treiman (1953) describing the effect of a ring current on cosmic ray cutoff rigidities. It is also shown that for the analysis of the characteristic properties of the correlation between cutoff rigidity variations and specific geomagnetic perturbations the rigidity corresponding to the first ''discontinuity band'' of the rigidity spectrum is an extremely useful parameter
Leonhard Euler and the mechanics of rigid bodies
Marquina, J. E.; Marquina, M. L.; Marquina, V.; Hernández-Gómez, J. J.
2017-01-01
In this work we present the original ideas and the construction of the rigid bodies theory realised by Leonhard Euler between 1738 and 1775. The number of treatises written by Euler on this subject is enormous, including the most notorious Scientia Navalis (1749), Decouverte d’un noveau principe de mecanique (1752), Du mouvement de rotation des corps solides autour d’un axe variable (1765), Theoria motus corporum solidorum seu rigidorum (1765) and Nova methodus motu corporum rigidorum determinandi (1776), in which he developed the ideas of the instantaneous rotation axis, the so-called Euler equations and angles, the components of what is now known as the inertia tensor, the principal axes of inertia, and, finally, the generalisation of the translation and rotation movement equations for any system. Euler, the man who ‘put most of mechanics into its modern form’ (Truesdell 1968 Essays in the History of Mechanics (Berlin: Springer) p 106).
Rigid Calabi-Yau threefolds, Picard Eisenstein series and instantons
International Nuclear Information System (INIS)
Bao, L; Kleinschmidt, A; Nilsson, B E W; Persson, D; Pioline, B
2013-01-01
Type IIA string theory compactified on a rigid Calabi-Yau threefold gives rise to a classical moduli space that carries an isometric action of U(2, 1). Various quantum corrections break this continuous isometry to a discrete subgroup. Focussing on the case where the intermediate Jacobian of the Calabi-Yau admits complex multiplication by the ring of quadratic imaginary integers O_d, we argue that the remaining quantum duality group is an arithmetic Picard modular group PU(2, 1; O_d). Based on this proposal we construct an Eisenstein series invariant under this duality group and study its non-Abelian Fourier expansion. This allows the prediction of non-perturbative effects, notably the contribution of D2- and NS5-brane instantons. The present work extends our previous analysis in 0909.4299 which was restricted to the special case of the Gaussian integers O_1 = Z[i].
Rigid Calabi-Yau threefolds, Picard Eisenstein series and instantons
Bao, L.; Kleinschmidt, A.; Nilsson, B. E. W.; Persson, D.; Pioline, B.
2013-12-01
Type IIA string theory compactified on a rigid Calabi-Yau threefold gives rise to a classical moduli space that carries an isometric action of U(2, 1). Various quantum corrections break this continuous isometry to a discrete subgroup. Focussing on the case where the intermediate Jacobian of the Calabi-Yau admits complex multiplication by the ring of quadratic imaginary integers d, we argue that the remaining quantum duality group is an arithmetic Picard modular group PU(2, 1; d). Based on this proposal we construct an Eisenstein series invariant under this duality group and study its non-Abelian Fourier expansion. This allows the prediction of non-perturbative effects, notably the contribution of D2- and NS5-brane instantons. The present work extends our previous analysis in 0909.4299 which was restricted to the special case of the Gaussian integers 1 = Bbb Z[i].
Controlling elastic waves with small phononic crystals containing rigid inclusions
Peng, Pai
2014-05-01
We show that a two-dimensional elastic phononic crystal comprising rigid cylinders in a solid matrix possesses a large complete band gap below a cut-off frequency. A mechanical model reveals that the band gap is induced by negative effective mass density, which is affirmed by an effective medium theory based on field averaging. We demonstrate, by two examples, that such elastic phononic crystals can be utilized to design small devices to control low-frequency elastic waves. One example is a waveguide made of a two-layer anisotropic elastic phononic crystal, which can guide and bend elastic waves with wavelengths much larger than the size of the waveguide. The other example is the enhanced elastic transmission of a single-layer elastic phononic crystal loaded with solid inclusions. The effective mass density and reciprocal of the modulus of the single-layer elastic phononic crystal are simultaneously near zero. © CopyrightEPLA, 2014.
Matrix methods applied to engineering rigid body mechanics
Crouch, T.
The purpose of this book is to present the solution of a range of rigorous body mechanics problems using a matrix formulation of vector algebra. Essential theory concerning kinematics and dynamics is formulated in terms of matrix algebra. The solution of kinematics and dynamics problems is discussed, taking into account the velocity and acceleration of a point moving in a circular path, the velocity and acceleration determination for a linkage, the angular velocity and angular acceleration of a roller in a taper-roller thrust race, Euler's theroem on the motion of rigid bodies, an automotive differential, a rotating epicyclic, the motion of a high speed rotor mounted in gimbals, and the vibration of a spinning projectile. Attention is given to the activity of a force, the work done by a conservative force, the work and potential in a conservative system, the equilibrium of a mechanism, bearing forces due to rotor misalignment, and the frequency of vibrations of a constrained rod.
Liquid crystallinity in flexible and rigid rod polymers
International Nuclear Information System (INIS)
Pickett, Galen T.; Schweizer, Kenneth S.
2000-01-01
We apply an anisotropic version of the polymer reference interaction site model (PRISM) integral equation description of flexible polymers to analyze athermal liquid crystallinity. The polymers are characterized by a statistical segment length, σ o , and by a physical hard-core thickness, d, that prevents the overlap of monomers on different chains. At small segment densities, ρ, the microscopic length scale d is irrelevant (as it must be in the universal semidilute regime), but becomes important in concentrated solutions and melts. Under the influence of the excluded volume interactions alone, the chains undergo a lyotropic, first-order isotropic-nematic transition at a concentration dependent upon the dimensionless ''aspect ratio,'' σ o /d. The transition becomes weaker as d→0, becoming second order, as has been previously shown. We extend the theory to describe the transition of rigid, thin rods, and discuss the evolution of the anisotropic liquid structure in the ordered phase. (c) 2000 American Institute of Physics
Stresses in Circular Plates with Rigid Elements
Velikanov, N. L.; Koryagin, S. I.; Sharkov, O. V.
2018-05-01
Calculations of residual stress fields are carried out by numerical and static methods, using the flat cross-section hypothesis. The failure of metal when exposed to residual stresses is, in most cases, brittle. The presence in the engineering structures of rigid elements often leads to the crack initiation and structure failure. This is due to the fact that rigid elements under the influence of external stresses are stress concentrators. In addition, if these elements are fixed by welding, the residual welding stresses can lead to an increase in stress concentration and, ultimately, to failure. The development of design schemes for such structures is a very urgent task for complex technical systems. To determine the stresses in a circular plate with a welded circular rigid insert under the influence of an external load, one can use the solution of the plane stress problem for annular plates in polar coordinates. The polar coordinates of the points are the polar radius and the polar angle, and the stress state is determined by normal radial stresses, tangential and shearing stresses. The use of the above mentioned design schemes, formulas, will allow more accurate determination of residual stresses in annular welded structures. This will help to establish the most likely directions of failure and take measures at the stages of designing, manufacturing and repairing engineering structures to prevent these failures. However, it must be taken into account that the external load, the presence of insulation can lead to a change in the residual stress field.
DeBate, Rita D; Severson, Herbert H; Cragun, Deborah L; Gau, Jeff M; Merrell, Laura K; Bleck, Jennifer R; Christiansen, Steve; Koerber, Anne; Tomar, Scott L; McCormack Brown, Kelli R; Tedesco, Lisa A; Hendricson, William
2013-06-01
Oral healthcare providers have a clinical opportunity for early detection of disordered eating behaviors because they are often the first health professionals to observe overt oral and physical signs. Curricula regarding early recognition of this oral/systemic medical condition are limited in oral health educational programs. Web-based learning can supplement and reinforce traditional learning and has the potential to develop skills. The study purpose was to determine the efficacy of a theory-driven Web-based training program to increase the capacity of oral health students to perform behaviors related to the secondary prevention of disordered eating behaviors. Using the Reach, Effectiveness, Adoption, Implementation and Maintenance evaluation framework, a longitudinal group-randomized controlled trial involving 27 oral health classes from 12 oral health education programs in the United States was implemented to assess the efficacy of the Web-based training on attitudes, knowledge, self-efficacy and skills related to the secondary prevention of disordered eating behaviors. Mixed-model analysis of covariance indicated substantial improvements among students in the intervention group (effect sizes: 0.51-0.83) on all six outcomes of interest. Results suggest that the Web-based training program may increase the capacity of oral healthcare providers to deliver secondary prevention of disordered eating behaviors. Implications and value of using the Reach, Effectiveness, Adoption, Implementation and Maintenance framework are discussed.
Allison, Stuart A; Xin, Yao
2005-08-15
A boundary element (BE) procedure is developed to numerically calculate the electrophoretic mobility of highly charged, rigid model macroions in the thin double layer regime based on the continuum primitive model. The procedure is based on that of O'Brien (R.W. O'Brien, J. Colloid Interface Sci. 92 (1983) 204). The advantage of the present procedure over existing BE methodologies that are applicable to rigid model macroions in general (S. Allison, Macromolecules 29 (1996) 7391) is that computationally time consuming integrations over a large number of volume elements that surround the model particle are completely avoided. The procedure is tested by comparing the mobilities derived from it with independent theory of the mobility of spheres of radius a in a salt solution with Debye-Huckel screening parameter, kappa. The procedure is shown to yield accurate mobilities provided (kappa)a exceeds approximately 50. The methodology is most relevant to model macroions of mean linear dimension, L, with 1000>(kappa)L>100 and reduced absolute zeta potential (q|zeta|/k(B)T) greater than 1.0. The procedure is then applied to the compact form of high molecular weight, duplex DNA that is formed in the presence of the trivalent counterion, spermidine, under low salt conditions. For T4 DNA (166,000 base pairs), the compact form is modeled as a sphere (diameter=600 nm) and as a toroid (largest linear dimension=600 nm). In order to reconcile experimental and model mobilities, approximately 95% of the DNA phosphates must be neutralized by bound counterions. This interpretation, based on electrokinetics, is consistent with independent studies.
49 CFR 587.18 - Dimensions of fixed rigid barrier.
2010-10-01
... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) DEFORMABLE BARRIERS Offset Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not... 49 Transportation 7 2010-10-01 2010-10-01 false Dimensions of fixed rigid barrier. 587.18 Section...
[The development of gender identity beyond rigid dichotomy].
Quindeau, Ilka
2014-01-01
The conflicts individuals with ambiguous sexual characteristics suffer from are not the result of genetic features but of the rigid and dichotomous gender order, which is currently undergoing a renaissance. This also applies to individuals with an uncertain gender identity. In the best interests of the child a concept of gender seems necessary, that goes beyond a binary separation and allows gender-specific intermediary stages in the personal development of identity. Such a gender concept can be developed following psychoanalytic theories. The present discourse contains a scale of connecting factors for a differentiated and less normative conceptualization of gender development. Starting from Freud's concept of constitutional bisexuality, Robert Stoller's theory, which has been firmly rooted in the mainstream of psychoanalysis for more than 40 years, will be critically reviewed. By involving Reimut Reiche's and Jean Laplanche's arguments, a continuative psychological gender theory will be drafted, which does not normatively and reductively claim the demarcation of gender, but rather opens up a space for gender diversity.
Leece, Pamela; Buchman, Daniel Z; Hamilton, Michael; Timmings, Caitlyn; Shantharam, Yalnee; Moore, Julia; Furlan, Andrea D
2017-04-26
In North America, drug overdose deaths are reaching unprecedented levels, largely driven by increasing prescription opioid-related deaths. Despite the development of several opioid guidelines, prescribing behaviours still contribute to poor patient outcomes and societal harm. Factors at the provider and system level may hinder or facilitate the application of evidence-based guidelines; interventions designed to address such factors are needed. Using implementation science and behaviour change theory, we have planned the development and evaluation of a comprehensive Opioid Self-Assessment Package, designed to increase adherence to the Canadian Opioid Guideline among family physicians. The intervention uses practical educational and self-assessment tools to provide prescribers with feedback on their current knowledge and practices, and resources to improve their practice. The evaluation approach uses a pretest and post-test design and includes both quantitative and qualitative methods at baseline and 6 months. We will recruit a purposive sample of approximately 10 family physicians in Ontario from diverse practice settings, who currently treat patients with long-term opioid therapy for chronic pain. Quantitative data will be analysed using basic descriptive statistics, and qualitative data will be analysed using the Framework Method. The University Health Network Research Ethics Board approved this study. Dissemination plan includes publications, conference presentations and brief stakeholder reports. This evidence-informed, theory-driven intervention has implications for national application of opioid quality improvement tools in primary care settings. We are engaging experts and end users in advisory and stakeholder roles throughout our project to increase its national relevance, application and sustainability. The performance measures could be used as the basis for health system quality improvement indicators to monitor opioid prescribing. Additionally, the
Directory of Open Access Journals (Sweden)
Neeraj Kumar
2015-08-01
Full Text Available Internet of Vehicles (IoV is a leading technology of the present era. It has gained huge attention with respect to its implementation in wide variety of domains ranging from traffic safety to infotainment applications. However, IoV can also be extended to healthcare domain, where the patients can be provided healthcare services on-the-fly. We extend this novel concept in this paper and refer it as “Healthcare services on-the-fly”. The concept of game theory has been used among the vehicles to access the healthcare services while traveling. The vehicles act as players in the game and tend to form and split coalitions to access these services. Learning automata (LA act as the players for interaction with the environment and take appropriate actions based on reward and penalty. Apart from this, Virtual Machine (VM scheduling algorithm for efficient utilization of resources at cloud level has also been formulated. A stochastic reward net (SRN-based model is used to represent the coalition formation and splitting with respect to availability of resources at cloud level. The performance of the proposed scheme is evaluated using various performance evaluation metrics. The results obtained prove the effectiveness of the proposed scheme in comparison to the best, first, and random fit schemes.
Influence of flock coating on bending rigidity of woven fabrics
Ozdemir, O.; Kesimci, M. O.
2017-10-01
This work presents the preliminary results of our efforts that focused on the effect of the flock coating on the bending rigidity of woven fabrics. For this objective, a laboratory scale flocking unit is designed and flocked samples of controlled flock density are produced. Bending rigidity of the samples with different flock densities are measured on both flocked and unflocked sides. It is shown that the bending rigidity depends on both flock density and whether the side to be measured is flocked or not. Adhesive layer thickness on the bending rigidity is shown to be dramatic. And at higher basis weights, flock density gets less effective on bending rigidity.
Cowan, Logan T.; Van Wagenen, Sarah A.; Brown, Brittany A.; Hedin, Riley J.; Seino-Stephan, Yukiko; Hall, P. Cougar; West, Joshua H.
2013-01-01
Objective. To quantify the presence of health behavior theory constructs in iPhone apps targeting physical activity. Methods. This study used a content analysis of 127 apps from Apple's (App Store) "Health & Fitness" category. Coders downloaded the apps and then used an established theory-based instrument to rate each app's inclusion of…
Understanding geological processes: Visualization of rigid and non-rigid transformations
Shipley, T. F.; Atit, K.; Manduca, C. A.; Ormand, C. J.; Resnick, I.; Tikoff, B.
2012-12-01
Visualizations are used in the geological sciences to support reasoning about structures and events. Research in cognitive sciences offers insights into the range of skills of different users, and ultimately how visualizations might support different users. To understand the range of skills needed to reason about earth processes we have developed a program of research that is grounded in the geosciences' careful description of the spatial and spatiotemporal patterns associated with earth processes. In particular, we are pursuing a research program that identifies specific spatial skills and investigates whether and how they are related to each other. For this study, we focus on a specific question: Is there an important distinction in the geosciences between rigid and non-rigid deformation? To study a general spatial thinking skill we employed displays with non-geological objects that had been altered by rigid change (rotation), and two types of non-rigid change ("brittle" (or discontinuous) and "ductile" (or continuous) deformation). Disciplinary scientists (geosciences and chemistry faculty), and novices (non-science faculty and undergraduate psychology students) answered questions that required them to visualize the appearance of the object before the change. In one study, geologists and chemists were found to be superior to non-science faculty in reasoning about rigid rotations (e.g., what an object would look like from a different perspective). Geologists were superior to chemists in reasoning about brittle deformations (e.g., what an object looked like before it was broken - here the object was a word cut into many fragments displaced in different directions). This finding is consistent with two hypotheses: 1) Experts are good at visualizing the types of changes required for their domain; and 2) Visualization of rigid and non-rigid changes are not the same skill. An additional important finding is that there was a broad range of skill in both rigid and non-rigid
Normalized inverse characterization of sound absorbing rigid porous media.
Zieliński, Tomasz G
2015-06-01
This paper presents a methodology for the inverse characterization of sound absorbing rigid porous media, based on standard measurements of the surface acoustic impedance of a porous sample. The model parameters need to be normalized to have a robust identification procedure which fits the model-predicted impedance curves with the measured ones. Such a normalization provides a substitute set of dimensionless (normalized) parameters unambiguously related to the original model parameters. Moreover, two scaling frequencies are introduced, however, they are not additional parameters and for different, yet reasonable, assumptions of their values, the identification procedure should eventually lead to the same solution. The proposed identification technique uses measured and computed impedance curves for a porous sample not only in the standard configuration, that is, set to the rigid termination piston in an impedance tube, but also with air gaps of known thicknesses between the sample and the piston. Therefore, all necessary analytical formulas for sound propagation in double-layered media are provided. The methodology is illustrated by one numerical test and by two examples based on the experimental measurements of the acoustic impedance and absorption of porous ceramic samples of different thicknesses and a sample of polyurethane foam.
Bhattarai, Gyanendra; Dhungana, Shailesh; Nordell, Bradley J.; Caruso, Anthony N.; Paquette, Michelle M.; Lanford, William A.; King, Sean W.
2018-05-01
Analytical expressions describing ion-induced sputter or etch processes generally relate the sputter yield to the surface atomic binding energy (Usb) for the target material. While straightforward to measure for the crystalline elemental solids, Usb is more complicated to establish for amorphous and multielement materials due to composition-driven variations and incongruent sublimation. In this regard, we show that for amorphous multielement materials, the ion-driven yield can instead be better understood via a consideration of mechanical rigidity and network topology. We first demonstrate a direct relationship between Usb, bulk modulus, and ion sputter yield for the elements, and then subsequently prove our hypothesis for amorphous multielement compounds by demonstrating that the same relationships exist between the reactive ion etch (RIE) rate and nanoindentation Young's modulus for a series of a -Si Nx :H and a -Si OxCy :H thin films. The impact of network topology is further revealed via application of the Phillips-Thorpe theory of topological constraints, which directly relates the Young's modulus to the mean atomic coordination () for an amorphous solid. The combined analysis allows the trends and plateaus in the RIE rate to be ultimately reinterpreted in terms of the atomic structure of the target material through a consideration of . These findings establish the important underlying role of mechanical rigidity and network topology in ion-solid interactions and provide additional considerations for the design and optimization of radiation-hard materials in nuclear and outer space environments.
Rigidity of complete generic shrinking Ricci solitons
Chu, Yawei; Zhou, Jundong; Wang, Xue
2018-01-01
Let (Mn , g , X) be a complete generic shrinking Ricci soliton of dimension n ≥ 3. In this paper, by employing curvature inequalities, the formula of X-Laplacian for the norm square of the trace-free curvature tensor, the weak maximum principle and the estimate of the scalar curvature of (Mn , g) , we prove some rigidity results for (Mn , g , X) . In particular, it is showed that (Mn , g , X) is isometric to Rn or a finite quotient of Sn under a pointwise pinching condition. Moreover, we establish several optimal inequalities and classify those shrinking solitons for equalities.
Strand Tension Control in Anchor Span for Suspension Bridge Using Dynamic Balance Theory
Directory of Open Access Journals (Sweden)
Da Wang
Full Text Available Abstract Strand tension control is essential in suspension bridge safety. However, few quantitative studies have examined the bending rigidity and boundary condition behavior of strands in the anchor span of suspension bridges because of their special structure and complex configuration. In this paper, a new calculation method for strand tension is explored by using dynamic balance theory to determine the effect of bending rigidity and boundary conditions. The accuracy and effectiveness of the proposed method are tested and confirmed with verification examples and application on Nanxi Yangtze Suspension Bridge in China. The results indicated that only low-order frequency calculation could be used to calculate the strand tension without considering the effect of bending rigidity to ensure control accuracy. The influence of bending rigidity on the control precision is related to the tension and the length of the strands, which is significantly determined by the specific value between the stress rigidity and the bending rigidity. The uncertain boundary conditions of the anchor span cable, which are fixed between consolidated and hinged, also have a major effect on the control accuracy. To improve the accuracy of strand tension control, the least squares method is proposed during the tension construction control of the anchor span. This approach can significantly improve the accuracy of the tension control of the main cable strand. Some recommendations for future bridge analysis are provided based on the results of this study.
Knowledge-in-action: a study on the integration of forces and energy in a rigid body
Directory of Open Access Journals (Sweden)
Consuelo Escudero
2009-03-01
Full Text Available This paper intends to go on with the study of problem solving in a compatible way with the theories of conceptual fields (TCC of Vergnaud (1990,1994,1998 and mental models of Johnson-Laird (1983,1990. Together with findings of another study (Escudero & Jaime 2007, some achievements and difficulties of freshmore engineering students when solving problems of the motion of rigid body in terms of the knowledge-in-action are analysed. The research methodology under a qualitative paradigm grouped data into categories which are not provided a priori by the theoretical framework. It can be said that the quality of the conceptual representation has been explicit in the quality of the proposed solution. Some meanings introduced by students in their problem solving activities can be characterized as operational invariants.
Public policies targeting labour market rigidities
Directory of Open Access Journals (Sweden)
Andreea Claudia ŞERBAN
2013-02-01
Full Text Available Labour market rigidity becomes an issue of increasing importance under conditions of shocks associated with the economic crisis due to the need to increase the adaptability and responsiveness to them. Thus, labour market policies must be directed towards mitigating rigidities caused by institutional or demographic factors or certain mismatch between demand and supply of education qualifications. This paper highlights the major role of the active labour market policies targeting the increase of labour flexibility, stressing the importance and impact on the ability to adapt quickly and effectively to macroeconomic shocks. Located on a declining trend in the years preceding the crisis, spending on labour market policies increased in 2009 in all the Member States of the European Union. Spending differences are significant between countries, Romania being at the lowest end of the European Union. This requires special attention because the increased adaptability of workers through training, as active measure, is of major importance considering the increased speed of changes in the labour market.
Optimized imaging using non-rigid registration
International Nuclear Information System (INIS)
Berkels, Benjamin; Binev, Peter; Blom, Douglas A.; Dahmen, Wolfgang; Sharpley, Robert C.; Vogt, Thomas
2014-01-01
The extraordinary improvements of modern imaging devices offer access to data with unprecedented information content. However, widely used image processing methodologies fall far short of exploiting the full breadth of information offered by numerous types of scanning probe, optical, and electron microscopies. In many applications, it is necessary to keep measurement intensities below a desired threshold. We propose a methodology for extracting an increased level of information by processing a series of data sets suffering, in particular, from high degree of spatial uncertainty caused by complex multiscale motion during the acquisition process. An important role is played by a non-rigid pixel-wise registration method that can cope with low signal-to-noise ratios. This is accompanied by formulating objective quality measures which replace human intervention and visual inspection in the processing chain. Scanning transmission electron microscopy of siliceous zeolite material exhibits the above-mentioned obstructions and therefore serves as orientation and a test of our procedures. - Highlights: • Developed a new process for extracting more information from a series of STEM images. • An objective non-rigid registration process copes with distortions. • Images of zeolite Y show retrieval of all information available from the data set. • Quantitative measures of registration quality were implemented. • Applicable to any serially acquired data, e.g. STM, AFM, STXM, etc
Directory of Open Access Journals (Sweden)
Catalin Angelo Ioan
2012-02-01
Full Text Available In the consumer’s theory, a crucial problem is to determine the substitution effect and therevenue effect in the case of one good price’s modifing. There exists two theories due to John RichardHicks and Eugen Slutsky which allocates differentsshares of the total change of the consumption tothese effects. The paper makes an analysis betweenthe two effects, considering the general case of aCES utility function and introduces three indicators which will characterize these shares.
Design of semi-rigid type of flexible pavements
Directory of Open Access Journals (Sweden)
Pranshoo Solanki
2017-03-01
Full Text Available The primary objective of the study presented in this paper is to develop design curves for performance prediction of stabilized layers and to compare semi-rigid flexible pavement designs between the empirical AASHTO 1993 and the mechanistic-empirical pavement design methodologies. Specifically, comparisons were made for a range of different sections consisting of cementitious layers stabilized with different types and percentages of additives. It is found that the design thickness is influenced by the type of soil, additive, selection of material property and design method. Cost comparisons of sections stabilized with different percentage and type of additives showed that CKD-stabilization provides economically low cost sections as compared to lime- and CFA-stabilized sections. Knowledge gained from the parametric analysis of different sections using AASHTO 1993 and MEPDG is expected to be useful to pavement designers and others in implementation of the new MEPDG for future pavement design. Keywords: Semi-rigid, Mechanistic, Resilient modulus, Fatigue life, Reliability, Traffic
Gavens, Lucy; Holmes, John; Buykx, Penny; de Vocht, Frank; Egan, Matt; Grace, Daniel; Lock, Karen; Mooney, John D; Brennan, Alan
2017-06-13
Recent years have seen a rise in new and innovative policies to reduce alcohol consumption and related harm in England, which can be implemented by local, as opposed to national, policy-makers. The aim of this paper is to explore the processes that underpin the adoption of these alcohol policies within local authorities. In particular, it aims to assess whether the concept of policy transfer (i.e. a process through which knowledge about policies in one place is used in the development of policies in another time or place) provides a useful model for understanding local alcohol policy-making. Qualitative data generated through in-depth interviews and focus groups from five case study sites across England were used to explore stakeholder experiences of alcohol policy transfer between local authorities. The purposive sample of policy actors included representatives from the police, trading standards, public health, licensing, and commissioning. Thematic analysis was used inductively to identify key features in the data. Themes from the policy transfer literature identified in the data were: policy copying, emulating, hybridization, and inspiration. Participants described a multitude of ways in which learning was shared between places, ranging from formal academic evaluation to opportunistic conversations in informal settings. Participants also described facilitators and constraints to policy transfer, such as the historical policy context and the local cultural, economic, and bureaucratic context, which influenced whether or not a policy that was perceived to work in one place might be transferred successfully to another context. Theories of policy transfer provide a promising framework for characterising processes of local alcohol policy-making in England, extending beyond debates regarding evidence-informed policy to account for a much wider range of considerations. Applying a policy transfer lens enables us to move beyond simple (but still important) questions of
V.S. Utkin; S.A. Solovyov
2015-01-01
The article proposes the method of calculating the bearing capacity of reinforced concrete beams at the operational stage by the rigidity (deflection) criterion. The methods, which were used in the article, are integral test and probabilistic methods for describing random variables. The author offers a new technique of calculating a deflection limit by a criterion of residual deformations. The article exemplifies the usage of the evidence theory for statistical information processing in the f...
Directory of Open Access Journals (Sweden)
Mefkur Bakan
2014-06-01
Full Text Available OBJECTIVE:Laryngoscopy and stimuli inside the trachea cause an intense sympatho-adrenal response. Remifentanil seems to be the optimal opioid for rigid bronchoscopy due to its potent and short-acting properties. The purpose of this study was to compare bolus propofol and ketamine as an adjuvant to remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy.MATERIALS AND METHODS:Forty children under 12 years of age who had been scheduled for a rigid bronchoscopy were included in this study. After midazolam premedication, a 1 µg/kg/min remifentanil infusion was started, and patients were randomly allocated to receive either propofol (Group P or ketamine (Group K as well as mivacurium for muscle relaxation. Anesthesia was maintained with a 1 µg/kg/min remifentanil infusion and bolus doses of propofol or ketamine. After the rigid bronchoscopy, 0.05 µg/kg/min of remifentanil was maintained until extubation. Hemodynamic parameters, emergence characteristics, and adverse events were evaluated.RESULTS:The demographic variables were comparable between the two groups. The decrease in mean arterial pressure from baseline values to the lowest values during rigid bronchoscopy was greater in Group P (p= 0.049, while the reduction in the other parameters and the incidence of adverse events were comparable between the two groups. The need for assisted or controlled mask ventilation after extubation was higher in Group K.CONCLUSION:Remifentanil-based total intravenous anesthesia with propofol or ketamine as an adjuvant drug along with controlled ventilation is a viable technique for pediatric rigid bronchoscopy. Ketamine does not provide a definite advantage over propofol with respect to hemodynamic stability during rigid bronchoscopy, while propofol seems more suitable during the recovery period.
Thermostability in rubredoxin and its relationship to mechanical rigidity
Rader, A. J.
2010-03-01
The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors.
Thermostability in rubredoxin and its relationship to mechanical rigidity
International Nuclear Information System (INIS)
Rader, A J
2010-01-01
The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors
Observational properties of rigidly rotating dust configurations
Energy Technology Data Exchange (ETDEWEB)
Ilyas, Batyr; Malafarina, Daniele [Nazarbayev University, Department of Physics, Astana (Kazakhstan); Yang, Jinye [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Bambi, Cosimo [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Eberhard-Karls Universitaet Tuebingen, Theoretical Astrophysics, Tuebingen (Germany)
2017-07-15
We study the observational properties of a class of exact solutions of Einstein's field equations describing stationary, axially symmetric, rigidly rotating dust (i.e. non-interacting particles). We ask the question whether such solutions can describe astrophysical rotating dark matter clouds near the center of galaxies and we probe the possibility that they may constitute an alternative to supermassive black holes at the center of galaxies. We show that light emission from accretion disks made of ordinary baryonic matter in this space-time has several differences with respect to the emission of light from similar accretion disks around black holes. The shape of the iron Kα line in the reflection spectrum of accretion disks can potentially distinguish this class of solutions from the Kerr metric, but this may not be possible with current X-ray missions. (orig.)
Management of rigid post-traumatic kyphosis.
Wu, S S; Hwa, S Y; Lin, L C; Pai, W M; Chen, P Q; Au, M K
1996-10-01
Rigid post-traumatic kyphosis after fracture of the thoracolumbar and lumbar spine represents a failure of initial management of the injury. Kyphosis moves the center of gravity anterior. The kyphosis and instability may result in pain, deformity, and increased neurologic deficits. Management for symptomatic post-traumatic kyphosis always has presented a challenge to orthopedic surgeons. To evaluate the surgical results of one stage posterior correction for rigid symptomatic post-traumatic kyphosis of the thoracolumbar and lumbar spine. The management for post-traumatic kyphosis remains controversial. Anterior, posterior, or combined anterior and posterior procedures have been advocated by different authors and show various degrees of success. One vertebra immediately above and below the level of the deformity was instrumented posteriorly by a transpedicular system (internal fixator AO). Posterior decompression was performed by excision of the spinal process and bilateral laminectomy. With the deformed vertebra through the pedicle, the vertebral body carefully is removed around the pedicle level, approximating a wedge shape. The extent to which the deformed vertebral body should be removed is determined by the attempted correction. Correction of the deformity is achieved by manipulation of the operating table and compression of the adjacent Schanz screws above and below the lesion. Thirteen patients with post-traumatic kyphosis with symptoms of fatigue and pain caused by slow progression of kyphotic deformities received posterior decompression, correction, and stabilization as a definitive treatment. The precorrection kyphosis ranged from 30-60 degrees, with a mean of 40 degrees +/- 10.8 degrees. After correction, kyphosis was reduced to an average of 1.5 degrees +/- 3.8 degrees, with a range from -5 degrees to 5 degrees. The average angle of correction was 38.8 degrees +/- 10.4 degrees, with a range from 25 degrees to 60 degrees. Significant difference was found
Dual Quaternion Variational Integrator for Rigid Body Dynamic Simulation
Xu, Jiafeng; Halse, Karl Henning
2016-01-01
In rigid body dynamic simulations, often the algorithm is required to deal with general situations where both reference point and inertia matrix are arbitrarily de- fined. We introduce a novel Lie group variational integrator using dual quaternion for simulating rigid body dynamics in all six degrees of freedom. Dual quaternion is used to represent rigid body kinematics and one-step Lie group method is used to derive dynamic equations. The combination of these two becomes the first Lie group ...
A DNA Origami Mechanical Device for the Regulation of Microcosmic Structural Rigidity.
Wan, Neng; Hong, Zhouping; Wang, Huading; Fu, Xin; Zhang, Ziyue; Li, Chao; Xia, Han; Fang, Yan; Li, Maoteng; Zhan, Yi; Yang, Xiangliang
2017-11-01
DNA origami makes it feasible to fabricate a tremendous number of DNA nanostructures with various geometries, dimensions, and functionalities. Moreover, an increasing amount of research on DNA nanostructures is focused on biological and biomedical applications. Here, the reversible regulation of microcosmic structural rigidity is accomplished using a DNA origami device in vitro. The designed DNA origami monomer is composed of an internal central axis and an external sliding tube. Due to the external tube sliding, the device transforms between flexible and rigid states. By transporting the device into the liposome, the conformational change of the origami device induces a structural change in the liposome. The results obtained demonstrate that the programmed DNA origami device can be applied to regulate the microcosmic structural rigidity of liposomes. Because microcosmic structural rigidity is important to cell proliferation and function, the results obtained potentially provide a foundation for the regulation of cell microcosmic structural rigidity using DNA nanostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Puncture mechanics of soft elastomeric membrane with large deformation by rigid cylindrical indenter
Liu, Junjie; Chen, Zhe; Liang, Xueya; Huang, Xiaoqiang; Mao, Guoyong; Hong, Wei; Yu, Honghui; Qu, Shaoxing
2018-03-01
Soft elastomeric membrane structures are widely used and commonly found in engineering and biological applications. Puncture is one of the primary failure modes of soft elastomeric membrane at large deformation when indented by rigid objects. In order to investigate the puncture failure mechanism of soft elastomeric membrane with large deformation, we study the deformation and puncture failure of silicone rubber membrane that results from the continuous axisymmetric indentation by cylindrical steel indenters experimentally and analytically. In the experiment, effects of indenter size and the friction between the indenter and the membrane on the deformation and puncture failure of the membrane are investigated. In the analytical study, a model within the framework of nonlinear field theory is developed to describe the large local deformation around the punctured area, as well as to predict the puncture failure of the membrane. The deformed membrane is divided into three parts and the friction contact between the membrane and indenter is modeled by Coulomb friction law. The first invariant of the right Cauchy-Green deformation tensor I1 is adopted to predict the puncture failure of the membrane. The experimental and analytical results agree well. This work provides a guideline in designing reliable soft devices featured with membrane structures, which are present in a wide variety of applications.
Axisymmetric wave propagation in gas shear flow confined by a rigid-walled pipeline
International Nuclear Information System (INIS)
Chen Yong; Huang Yi-Yong; Chen Xiao-Qian; Bai Yu-Zhu; Tan Xiao-Dong
2015-01-01
The axisymmetric acoustic wave propagating in a perfect gas with a shear pipeline flow confined by a circular rigid wall is investigated. The governing equations of non-isentropic and isentropic acoustic assumptions are mathematically deduced while the constraint of Zwikker and Kosten is relaxed. An iterative method based on the Fourier–Bessel theory is proposed to semi-analytically solve the proposed models. A comparison of numerical results with literature contributions validates the present contribution. Meanwhile, the features of some high-order transverse modes, which cannot be analyzed based on the Zwikker and Kosten theory, are analyzed (paper)
Investigation of Drag Coefficient for Rigid Ballute-like Shapes
Carnasciali, Maria-Isabel; Mastromarino, Anthony
2014-11-01
One common method of decelerating an object during atmospheric entry, descent, and landing is the use of parachutes. Another deceleration technology is the ballute - a combination of balloon and parachute. A CFD study was conducted using commercially available software to investigate the flow-field and the coefficient of drag for various rigid ballute-like shapes at varying Reynolds numbers. The impact of size and placement of the burble-fence as well as number, size, and shape of inlets was considered. Recent experimental measurements conducted during NASA's Low-Density Supersonic Decelerator program revealed a much higher coefficient of drag (Cd) for ballutes than previously encountered. Using atmospheric drag to slow down and land reduces the need for heavy fuel and rocket engines and thus, high values of drag are desired. Funding for this work, in part, provided by the CT Space Grant Consortium.
A virtual pebble game to ensemble average graph rigidity.
González, Luis C; Wang, Hui; Livesay, Dennis R; Jacobs, Donald J
2015-01-01
The body-bar Pebble Game (PG) algorithm is commonly used to calculate network rigidity properties in proteins and polymeric materials. To account for fluctuating interactions such as hydrogen bonds, an ensemble of constraint topologies are sampled, and average network properties are obtained by averaging PG characterizations. At a simpler level of sophistication, Maxwell constraint counting (MCC) provides a rigorous lower bound for the number of internal degrees of freedom (DOF) within a body-bar network, and it is commonly employed to test if a molecular structure is globally under-constrained or over-constrained. MCC is a mean field approximation (MFA) that ignores spatial fluctuations of distance constraints by replacing the actual molecular structure by an effective medium that has distance constraints globally distributed with perfect uniform density. The Virtual Pebble Game (VPG) algorithm is a MFA that retains spatial inhomogeneity in the density of constraints on all length scales. Network fluctuations due to distance constraints that may be present or absent based on binary random dynamic variables are suppressed by replacing all possible constraint topology realizations with the probabilities that distance constraints are present. The VPG algorithm is isomorphic to the PG algorithm, where integers for counting "pebbles" placed on vertices or edges in the PG map to real numbers representing the probability to find a pebble. In the VPG, edges are assigned pebble capacities, and pebble movements become a continuous flow of probability within the network. Comparisons between the VPG and average PG results over a test set of proteins and disordered lattices demonstrate the VPG quantitatively estimates the ensemble average PG results well. The VPG performs about 20% faster than one PG, and it provides a pragmatic alternative to averaging PG rigidity characteristics over an ensemble of constraint topologies. The utility of the VPG falls in between the most
Ghalyan, Ibrahim Fahad Jasim
2016-01-01
This book provides comprehensive and integrated approaches for rigid and flexible object assembly. It presents comparison studies with the available force-guided robotic processes and covers contact-state modeling, scheme control strategies, and position searching algorithms. Further, it includes experimental validations for different assembly situations, including those for the assembly of industrial parts taken from the automotive industry. .
On Li Zhi's Theory of Growing up in Spirit
Institute of Scientific and Technical Information of China (English)
Wang Junjiang
2006-01-01
The theory of growing up in spirit is the core of Li Zhi's thought.The theory attempts to get rid of the limit of the rigid ethical doctrine of Confucianismand to encourage growth in a helpful person for the benefit of the country,which demands both a free environment of society and enough courage and insight of the individual.At the same time,the criterion of growing up in spirit indicates the limitation of Li Zhi's thought.His free exploration,however,provides various revelations for us.
Klein, Felix; Nagem, Raymond J; Sandri, Guido
The Theory of the Top. Volume IV. Technical Applications of the Theory of the Top is the fourth and final volume in a series of self-contained English translations of the classic and definitive treatment of rigid body motion. Key features: * Complete and unabridged presentation with recent advances and additional notes; * Annotations by the translators provide insights into the nature of science and mathematics in the late 19th century; * Each volume interweaves theory and applications. The Theory of the Top was originally presented by Felix Klein as an 1895 lecture at Göttingen University that was broadened in scope and clarified as a result of collaboration with Arnold Sommerfeld. Graduate students and researchers interested in theoretical and applied mechanics will find this series of books a thorough and insightful account. Other volumes in the series include Introduction to the Kinematics and Kinetics of the Top, Development of the Theory in the Case of the Heavy Symmetric Top, and Perturbation...
Everri, Marina; Mancini, Tiziana; Fruggeri, Laura
Previous studies using Olson's Circumplex Model and FACES IV, the self-report assessing family functioning, did not clarify the role of rigidity, a dimension of this model. Rigidity emerged as ambiguous: it was considered either as a functional or as a dysfunctional dimension. Building upon the results of previous studies, we provided a contribution intended to disambiguate the role of rigidity considering adolescents' perceptions and using a non-a priori classification analysis. 320 Italian adolescents (13-21 years) participated in this study and responded to a questionnaire containing scales of the study variables. A latent class analysis was performed to identify the association of rigidity with the other dimensions of Olson's model and with indicators of adaptive family functioning in adolescence: parental monitoring and family satisfaction. We found six clusters corresponding to family typologies and having different levels of functioning. Rigidity emerged as adaptive in the typologies named rigidly balanced and flexibly oscillating; it was associated with positive dimensions of family functioning, i.e. flexibility, cohesion, parental monitoring, and high levels of family satisfaction. Differently, when rigidity was associated with disengagement, low cohesion and flexibility, and lack of parental supervision, emerged as maladaptive. This was the case of two typologies: the rigidly disengaged and the chaotically disengaged. Adolescents of these families reported the lowest levels of satisfaction. In the two last typologies, the flexibly chaotic and the cohesively disorganized, rigidity indicated a mid-range functionality as these families were characterized by emotional connectedness but lack of containment. Clinical implications are discussed.
Algebraic Methods for Counting Euclidean Embeddings of Rigid Graphs
I.Z. Emiris; E.P. Tsigaridas; A. Varvitsiotis (Antonios); E.R. Gasner
2009-01-01
textabstract The study of (minimally) rigid graphs is motivated by numerous applications, mostly in robotics and bioinformatics. A major open problem concerns the number of embeddings of such graphs, up to rigid motions, in Euclidean space. We capture embeddability by polynomial systems
Almost Poisson integration of rigid body systems
International Nuclear Information System (INIS)
Austin, M.A.; Krishnaprasad, P.S.; Li-Sheng Wang
1993-01-01
In this paper we discuss the numerical integration of Lie-Poisson systems using the mid-point rule. Since such systems result from the reduction of hamiltonian systems with symmetry by lie group actions, we also present examples of reconstruction rules for the full dynamics. A primary motivation is to preserve in the integration process, various conserved quantities of the original dynamics. A main result of this paper is an O(h 3 ) error estimate for the Lie-Poisson structure, where h is the integration step-size. We note that Lie-Poisson systems appear naturally in many areas of physical science and engineering, including theoretical mechanics of fluids and plasmas, satellite dynamics, and polarization dynamics. In the present paper we consider a series of progressively complicated examples related to rigid body systems. We also consider a dissipative example associated to a Lie-Poisson system. The behavior of the mid-point rule and an associated reconstruction rule is numerically explored. 24 refs., 9 figs
Rigid multipodal platforms for metal surfaces
Directory of Open Access Journals (Sweden)
Michal Valášek
2016-03-01
Full Text Available In this review the recent progress in molecular platforms that form rigid and well-defined contact to a metal surface are discussed. Most of the presented examples have at least three anchoring units in order to control the spatial arrangement of the protruding molecular subunit. Another interesting feature is the lateral orientation of these foot structures which, depending on the particular application, is equally important as the spatial arrangement of the molecules. The numerous approaches towards assembling and organizing functional molecules into specific architectures on metal substrates are reviewed here. Particular attention is paid to variations of both, the core structures and the anchoring groups. Furthermore, the analytical methods enabling the investigation of individual molecules as well as monomolecular layers of ordered platform structures are summarized. The presented multipodal platforms bearing several anchoring groups form considerably more stable molecule–metal contacts than corresponding monopodal analogues and exhibit an enlarged separation of the functional molecules due to the increased footprint, as well as restrict tilting of the functional termini with respect to the metal surface. These platforms are thus ideally suited to tune important properties of the molecule–metal interface. On a single-molecule level, several of these platforms enable the control over the arrangement of the protruding rod-type molecular structures (e.g., molecular wires, switches, rotors, sensors with respect to the surface of the substrate.
Inflatable Tubular Structures Rigidized with Foams
Tinker, Michael L.; Schnell, Andrew R.
2010-01-01
Inflatable tubular structures that have annular cross sections rigidized with foams, and the means of erecting such structures in the field, are undergoing development. Although the development effort has focused on lightweight structural booms to be transported in compact form and deployed in outer space, the principles of design and fabrication are also potentially applicable to terrestrial structures, including components of ultralightweight aircraft, lightweight storage buildings and shelters, lightweight insulation, and sales displays. The use of foams to deploy and harden inflatable structures was first proposed as early as the 1960s, and has been investigated in recent years by NASA, the U.S. Air Force Research Laboratory, industry, and academia. In cases of deployable booms, most of the investigation in recent years has focused on solid cross sections, because they can be constructed relatively easily. However, solid-section foam-filled booms can be much too heavy for some applications. In contrast, booms with annular cross sections according to the present innovation can be tailored to obtain desired combinations of stiffness and weight through choice of diameters, wall thicknesses, and foam densities. By far the most compelling advantage afforded by this innovation is the possibility of drastically reducing weights while retaining or increasing the stiffnesses, relative to comparable booms that have solid foamfilled cross sections. A typical boom according to this innovation includes inner and outer polyimide film sleeves to contain foam that is injected between them during deployment.
Spontaneous droplet trampolining on rigid superhydrophobic surfaces
Schutzius, Thomas M.; Jung, Stefan; Maitra, Tanmoy; Graeber, Gustav; Köhme, Moritz; Poulikakos, Dimos
2015-11-01
Spontaneous removal of condensed matter from surfaces is exploited in nature and in a broad range of technologies to achieve self-cleaning, anti-icing and condensation control. But despite much progress, our understanding of the phenomena leading to such behaviour remains incomplete, which makes it challenging to rationally design surfaces that benefit from its manifestation. Here we show that water droplets resting on superhydrophobic textured surfaces in a low-pressure environment can self-remove through sudden spontaneous levitation and subsequent trampoline-like bouncing behaviour, in which sequential collisions with the surface accelerate the droplets. These collisions have restitution coefficients (ratios of relative speeds after and before collision) greater than unity despite complete rigidity of the surface, and thus seemingly violate the second law of thermodynamics. However, these restitution coefficients result from an overpressure beneath the droplet produced by fast droplet vaporization while substrate adhesion and surface texture restrict vapour flow. We also show that the high vaporization rates experienced by the droplets and the associated cooling can result in freezing from a supercooled state that triggers a sudden increase in vaporization, which in turn boosts the levitation process. This effect can spontaneously remove surface icing by lifting away icy drops the moment they freeze. Although these observations are relevant only to systems in a low-pressure environment, they show how surface texturing can produce droplet-surface interactions that prohibit liquid and freezing water-droplet retention on surfaces.
Computing the Free Energy along a Reaction Coordinate Using Rigid Body Dynamics.
Tao, Peng; Sodt, Alexander J; Shao, Yihan; König, Gerhard; Brooks, Bernard R
2014-10-14
The calculations of potential of mean force along complex chemical reactions or rare events pathways are of great interest because of their importance for many areas in chemistry, molecular biology, and material science. The major difficulty for free energy calculations comes from the great computational cost for adequate sampling of the system in high-energy regions, especially close to the reaction transition state. Here, we present a method, called FEG-RBD, in which the free energy gradients were obtained from rigid body dynamics simulations. Then the free energy gradients were integrated along a reference reaction pathway to calculate free energy profiles. In a given system, the reaction coordinates defining a subset of atoms (e.g., a solute, or the quantum mechanics (QM) region of a quantum mechanics/molecular mechanics simulation) are selected to form a rigid body during the simulation. The first-order derivatives (gradients) of the free energy with respect to the reaction coordinates are obtained through the integration of constraint forces within the rigid body. Each structure along the reference reaction path is separately subjected to such a rigid body simulation. The individual free energy gradients are integrated along the reference pathway to obtain the free energy profile. Test cases provided demonstrate both the strengths and weaknesses of the FEG-RBD method. The most significant benefit of this method comes from the fast convergence rate of the free energy gradient using rigid-body constraints instead of restraints. A correction to the free energy due to approximate relaxation of the rigid-body constraint is estimated and discussed. A comparison with umbrella sampling using a simple test case revealed the improved sampling efficiency of FEG-RBD by a factor of 4 on average. The enhanced efficiency makes this method effective for calculating the free energy of complex chemical reactions when the reaction coordinate can be unambiguously defined by a
Ruble, Diane; Tamis-LeMonda, Catherine; Shrout, Patrick E.
2014-01-01
A key prediction of cognitive theories of gender development concerns developmental trajectories in the relative strength or rigidity of gender typing. To examine these trajectories in early childhood, 229 children (African American, Mexican, Dominican) were followed annually from age 3 to 5 and gender-stereotypical appearance, dress-up play, toy play, and sex segregation were examined. High gender-typing was found across ethnic group, and most behaviors increased in rigidity, especially from age 3 to 4. In addressing controversy surrounding the stability and structure of gender-typing it was found that from year to year, most behaviors showed moderately stable individual differences. Behaviors were uncorrelated within age, but showed more concordance in change across time, suggesting that aspects of gender-typing are multidimensional but still show coherence. PMID:23432471
Halim, May Ling; Ruble, Diane; Tamis-LeMonda, Catherine; Shrout, Patrick E
2013-01-01
A key prediction of cognitive theories of gender development concerns developmental trajectories in the relative strength or rigidity of gender typing. To examine these trajectories in early childhood, 229 children (African American, Mexican American, and Dominican American) were followed annually from age 3 to 5 years, and gender-stereotypical appearance, dress-up play, toy play, and sex segregation were examined. High gender-typing was found across ethnic groups, and most behaviors increased in rigidity, especially from age 3 to 4 years. In addressing controversy surrounding the stability and structure of gender-typing it was found that from year to year, most behaviors showed moderately stable individual differences. Behaviors were uncorrelated within age but showed more concordance in change across time, suggesting that aspects of gender-typing are multidimensional, but still show coherence. © 2013 The Authors. Child Development © 2013 Society for Research in Child Development, Inc.
Topological classification of the Goryachev integrable case in rigid body dynamics
International Nuclear Information System (INIS)
Nikolaenko, S S
2016-01-01
A topological analysis of the Goryachev integrable case in rigid body dynamics is made on the basis of the Fomenko-Zieschang theory. The invariants (marked molecules) which are obtained give a complete description, from the standpoint of Liouville classification, of the systems of Goryachev type on various level sets of the energy. It turns out that on appropriate energy levels the Goryachev case is Liouville equivalent to many classical integrable systems and, in particular, the Joukowski, Clebsch, Sokolov and Kovalevskaya-Yehia cases in rigid body dynamics, as well as to some integrable billiards in plane domains bounded by confocal quadrics -- in other words, the foliations given by the closures of generic solutions of these systems have the same structure. Bibliography: 15 titles
BUTCHER, PR; KALVERBOER, A; MINDERAA, RB; VANDOORMAAL, EF; TENWOLDE, Y
1993-01-01
The associations between a mother's rigidity, her sensitivity in early (3 month) interaction and the quality of her premature infant's attachment at 13 months were investigated. Rigidity as a personality characteristic was not found to be significantly associated with sensitivity or quality of
Lessard, Chantale; Contandriopoulos, André-Pierre; Beaulieu, Marie-Dominique
2010-06-01
Despite increasing interest in health economic evaluation, investigations have shown limited use by micro (clinical) level decision-makers. A considerable amount of health decisions take place daily at the point of the clinical encounter; especially in primary care. Since every decision has an opportunity cost, ignoring economic information in family physicians' (FPs) decision-making may have a broad impact on health care efficiency. Knowledge translation of economic evaluation is often based on taken-for-granted assumptions about actors' interests and interactions, neglecting much of the complexity of social reality. Health economics literature frequently assumes a rational and linear decision-making process. Clinical decision-making is in fact a complex social, dynamic, multifaceted process, involving relationships and contextual embeddedness. FPs are embedded in complex social networks that have a significant impact on skills, attitudes, knowledge, practices, and on the information being used. Because of their socially constructed nature, understanding preferences, professional culture, practices, and knowledge translation requires serious attention to social reality. There has been little exploration by health economists of whether the problem may be more fundamental and reside in a misunderstanding of the process of decision-making. There is a need to enhance our understanding of the role of economic evaluation in decision-making from a disciplinary perspective different than health economics. This paper argues for a different conceptualization of the role of economic evaluation in FPs' decision-making, and proposes Bourdieu's sociological theory as a research framework. Bourdieu's theory of practice illustrates how the context-sensitive nature of practice must be understood as a socially constituted practical knowledge. The proposed approach could substantially contribute to a more complex understanding of the role of economic evaluation in FPs' decision
Druţu, Cornelia
2018-01-01
The key idea in geometric group theory is to study infinite groups by endowing them with a metric and treating them as geometric spaces. This applies to many groups naturally appearing in topology, geometry, and algebra, such as fundamental groups of manifolds, groups of matrices with integer coefficients, etc. The primary focus of this book is to cover the foundations of geometric group theory, including coarse topology, ultralimits and asymptotic cones, hyperbolic groups, isoperimetric inequalities, growth of groups, amenability, Kazhdan's Property (T) and the Haagerup property, as well as their characterizations in terms of group actions on median spaces and spaces with walls. The book contains proofs of several fundamental results of geometric group theory, such as Gromov's theorem on groups of polynomial growth, Tits's alternative, Stallings's theorem on ends of groups, Dunwoody's accessibility theorem, the Mostow Rigidity Theorem, and quasiisometric rigidity theorems of Tukia and Schwartz. This is the f...
Prediction of flexible/rigid regions from protein sequences using k-spaced amino acid pairs
Directory of Open Access Journals (Sweden)
Ruan Jishou
2007-04-01
Full Text Available Abstract Background Traditionally, it is believed that the native structure of a protein corresponds to a global minimum of its free energy. However, with the growing number of known tertiary (3D protein structures, researchers have discovered that some proteins can alter their structures in response to a change in their surroundings or with the help of other proteins or ligands. Such structural shifts play a crucial role with respect to the protein function. To this end, we propose a machine learning method for the prediction of the flexible/rigid regions of proteins (referred to as FlexRP; the method is based on a novel sequence representation and feature selection. Knowledge of the flexible/rigid regions may provide insights into the protein folding process and the 3D structure prediction. Results The flexible/rigid regions were defined based on a dataset, which includes protein sequences that have multiple experimental structures, and which was previously used to study the structural conservation of proteins. Sequences drawn from this dataset were represented based on feature sets that were proposed in prior research, such as PSI-BLAST profiles, composition vector and binary sequence encoding, and a newly proposed representation based on frequencies of k-spaced amino acid pairs. These representations were processed by feature selection to reduce the dimensionality. Several machine learning methods for the prediction of flexible/rigid regions and two recently proposed methods for the prediction of conformational changes and unstructured regions were compared with the proposed method. The FlexRP method, which applies Logistic Regression and collocation-based representation with 95 features, obtained 79.5% accuracy. The two runner-up methods, which apply the same sequence representation and Support Vector Machines (SVM and Naïve Bayes classifiers, obtained 79.2% and 78.4% accuracy, respectively. The remaining considered methods are
Reversible Rigidity Control Using Low Melting Temperature Alloys
Shan, Wanliang; Lu, Tong; Majidi, Carmel
2013-03-01
Inspired by nature, materials able to achieve rapid rigidity changes have important applications for human body protection in military and many other areas. This talk presents the fabrication and design of soft-matter technologies that exhibit rapid reversible rigidity control. Fabricated with a masked deposition technique, the soft-matter composite contains liquid-phase and phase-changing metal alloys embedded in a soft and highly stretchable elastomer. The composite material can reversibly change its rigidity by three orders of magnitude and sustain large deformation.
The Almost Periodic Rigidity of Crystallographic Bar-Joint Frameworks
Directory of Open Access Journals (Sweden)
Ghada Badri
2014-04-01
Full Text Available A crystallographic bar-joint framework, C in Rd, is shown to be almost periodically infinitesimally rigid if and only if it is strictly periodically infinitesimally rigid and the rigid unit mode (RUM spectrum, Ω (C, is a singleton. Moreover, the almost periodic infinitesimal flexes of C are characterised in terms of a matrix-valued function, ΦC(z, on the d-torus, Td, determined by a full rank translation symmetry group and an associated motif of joints and bars.
APPLICATION OF RIGID LINKS IN STRUCTURAL DESIGN MODELS
Directory of Open Access Journals (Sweden)
Sergey Yu. Fialko
2017-09-01
Full Text Available A special finite element modelling rigid links is proposed for the linear static and buckling analysis. Unlike the classical approach based on the theorems of rigid body kinematics, the proposed approach preserves the similarity between the adjacency graph for a sparse matrix and the adjacency graph for nodes of the finite element model, which allows applying sparse direct solvers more effectively. Besides, the proposed approach allows significantly reducing the number of nonzero entries in the factored stiffness matrix in comparison with the classical one, which greatly reduces the duration of the solution. For buckling problems of structures containing rigid bodies, this approach gives correct results. Several examples demonstrate its efficiency.
Directory of Open Access Journals (Sweden)
Hasselberg Marie
2010-11-01
Full Text Available Abstract Background Road traffic injuries are a major global public health problem. Improvements in pre-hospital trauma care can help minimize mortality and morbidity from road traffic injuries (RTIs worldwide, particularly in low- and middle-income countries (LMICs with a high rate of RTIs such as Iran. The current study aimed to explore pre-hospital trauma care process for RTI victims in Iran and to identify potential areas for improvements based on the experience and perception of pre-hospital trauma care professionals. Methods A qualitative study design using a grounded theory approach was selected. The data, collected via in-depth interviews with 15 pre-hospital trauma care professionals, were analyzed using the constant comparative method. Results Seven categories emerged to describe the factors that hinder or facilitate an effective pre-hospital trauma care process: (1 administration and organization, (2 staff qualifications and competences, (3 availability and distribution of resources, (4 communication and transportation, (5 involved organizations, (6 laypeople and (7 infrastructure. The core category that emerged from the other categories was defined as "interaction and common understanding". Moreover, a conceptual model was developed based on the categories. Conclusions Improving the interaction within the current pre-hospital trauma care system and building a common understanding of the role of the Emergency Medical Services (EMS emerged as key issues in the development of an effective pre-hospital trauma care process.
Radlow, Madlen; Czjzek, Mirjam; Jeudy, Alexandra; Dabin, Jerome; Delage, Ludovic; Leblanc, Catherine; Hartung, Jens
2018-05-18
X-ray diffraction of native bromoperoxidase II (EC 1.11.1.18) from the brown alga Ascophyllum nodosum reveals at a resolution of 2.26 Å details of orthovanadate binding and homohexameric protein organization. Three dimers interwoven in contact regions and tightened by hydrogen-bond-clamped guanidinium stacks along with regularly aligned water molecules form the basic structure of the enyzme. Intra- and intermolecular disulfide bridges further stabilize the enzyme preventing altogether the protein from denaturing up to a temperature of 90 °C, as evident from dynamic light scattering and the on-gel ortho-dianisidine assay. Every monomer binds one equivalent of orthovanadate in a cavity formed from side chains of three histidines, two arginines, one lysine, serine, and tryptophan. Protein binding occurs primarily through hydrogen bridges and superimposed by Coulomb attraction according to thermochemical model on density functional level of theory (B3LYP/6-311++G**). The strongest attractor is the arginine side chain mimic N-methylguanidinium, enhancing in positive cooperative manner hydrogen bridges toward weaker acceptors, such as residues from lysine and serine. Activating hydrogen peroxide occurs in the thermochemical model by side-on binding in orthovanadium peroxoic acid, oxidizing bromide with virtually no activation energy to hydrogen bonded hypobromous acid.
Baker, Stephen B; Reid, Russell R; Burkey, Brooke; Bartlett, Scott P
2007-09-01
To shorten head frame wear time associated with external halo distraction (HD), we have adapted a protocol for maxillary distraction with the halo system that integrates plate fixation. All patients had a history of cleft lip and/or palate and maxillary retrusion > or = 8 mm. Five patients treated with this protocol and followed for at least 1 year were included in this study. The protocol included a 3-day latency period, variable maxillary distraction, and removal of the halo device with simultaneous rigid internal fixation. Two patients had a variable period of maxillomandibular fixation (MMF), which maintained the maxillary advancement and idealized intercuspal position while permitting further callus maturation. Cephalographs were obtained preoperatively, immediately following distractor removal, and 1 year after rigid internal fixation. The mean age at time of surgery was 18.7 years. The maxillary deficiency ranged from 8 to 15 mm (mean = 10.6 mm). All five patients demonstrated excellent occlusion. Cephalometric analysis 1-year post rigid internal fixation revealed minimal (maxillary distraction followed by MMF to maintain maxillary advancement may reduce halo device wear to 1 to 2 weeks. MMF optimizes occlusion by forcing the maxillary teeth into maximal intercuspal position. Rigid fixation is not only associated with less long-term relapse compared to nonrigid forms of fixation, but also minimizes the incidence of nonunion. This treatment protocol provides the advancement possible with distraction osteogenesis and the accuracy of orthognathic surgery, thereby minimizing external head frame wear.
A study of semi-rigid support on ankle supination sprain kinematics.
Tang, Y M; Wu, Z H; Liao, W H; Chan, K M
2010-12-01
Ankle sprain injury is very common in sports and the use of ankle support is crucial. This research investigated the effect of an ankle brace in reducing the ankle angular displacement and angular velocity during sudden supination. In the experiment, 11 healthy males were tested. The bracing condition, semi-rigid ankle braces were investigated. The angular displacement and angular velocity of the ankle were computed. The motion-capture system was adopted to capture the three-dimensional coordinates of the reflective markers. The coordinates of the reflective markers were used to compute the ankle kinematics during simulated ankle supination. A mechanical supination platform was used to simulate the sprain motions. Experimental results showed that the semi-rigid brace tested significantly reduced the ankle angular displacement and angular velocity compared with control conditions during sudden supination. In conclusion, the semi-rigid-type brace can provide significant restriction to reduce the magnitudes of the angular displacement and angular velocity of the ankle during sudden supination sprain. The semi-rigid-type brace is suggested as the prophylactic bracing for the ankle. © 2009 John Wiley & Sons A/S.
Can deformation of a polymer film with a rigid coating model geophysical processes?
Volynskii, A. L.; Bazhenov, S. L.
2007-12-01
The structural and mechanical behavior of polymer films with a thin rigid coating is analyzed. The behavior of such systems under applied stress is accompanied by the formation of a regular wavy surface relief and by regular fragmentation of the coating. The above phenomena are shown to be universal. Both phenomena (stress-induced development of a regular wavy surface relief and regular fragmentation of the coating) are provided by the specific features of mechanical stress transfer from a compliant soft support to a rigid thin coating. The above phenomena are associated with a specific structure of the system, which is referred to as “a rigid coating on a soft substratum” system (RCSS). Surface microrelief in RCSS systems is similar to the ocean floor relief in the vicinity of mid-oceanic ridges. Thus, the complex system composed of a young oceanic crust and upper Earth's mantle may be considered as typically “a solid coating on a soft substratum” system. Specific features of the ocean floor relief are analyzed in terms of the approach advanced for the description of the structural mechanical behavior of polymer films with a rigid coating. This analysis allowed to estimate the strength of an ocean floor.
International Nuclear Information System (INIS)
Zhang Xuping; Mills, James K.; Cleghorn, William L.
2009-01-01
Modeling of multibody dynamics with flexible links is a challenging task, which not only involves the effect of rigid body motion on elastic deformations, but also includes the influence of elastic deformations on rigid body motion. This paper presents coupling characteristics of rigid body motions and elastic motions of a 3-PRR parallel manipulator with three flexible intermediate links. The intermediate links are modeled as Euler-Bernoulli beams with pinned-pinned boundary conditions based on the assumed mode method (AMM). Using Lagrange multipliers, the fully coupled equations of motions of the flexible parallel manipulator are developed by incorporating the rigid body motions with elastic motions. The mutual dependence of elastic deformations and rigid body motions are investigated from the analysis of the derived equations of motion. Open-loop simulation without joint motion controls and closed-loop simulation with joint motion controls are performed to illustrate the effect of elastic motion on rigid body motions and the coupling effect amongst flexible links. These analyses and results provide valuable insight to the design and control of the parallel manipulator with flexible intermediate links
Mondal, Bhaskar; Neese, Frank; Ye, Shengfa
2015-08-03
The development of efficient catalysts with base metals for CO2 hydrogenation has always been a major thrust of interest. A series of experimental and theoretical work has revealed that the catalytic cycle typically involves two key steps, namely, base-promoted heterolytic H2 splitting and hydride transfer to CO2, either of which can be the rate-determining step (RDS) of the entire reaction. To explore the determining factor for the nature of RDS, we present herein a comparative mechanistic investigation on CO2 hydrogenation mediated by [M(H)(η(2)-H2)(PP3(Ph))](n+) (M = Fe(II), Ru(II), and Co(III); PP3(Ph) = tris(2-(diphenylphosphino)phenyl)phosphine) type complexes. In order to construct reliable free energy profiles, we used highly correlated wave function based ab initio methods of the coupled cluster type alongside the standard density functional theory. Our calculations demonstrate that the hydricity of the metal-hydride intermediate generated by H2 splitting dictates the nature of the RDS for the Fe(II) and Co(III) systems, while the RDS for the Ru(II) catalyst appears to be ambiguous. CO2 hydrogenation catalyzed by the Fe(II) complex that possesses moderate hydricity traverses an H2-splitting RDS, whereas the RDS for the high-hydricity Co(III) species is found to be the hydride transfer. Thus, our findings suggest that hydricity can be used as a practical guide in future catalyst design. Enhancing the electron-accepting ability of low-hydricity catalysts is likely to improve their catalytic performance, while increasing the electron-donating ability of high-hydricity complexes may speed up CO2 conversion. Moreover, we also established the active roles of base NEt3 in directing the heterolytic H2 splitting and assisting product release through the formation of an acid-base complex.
Multiscale weighted colored graphs for protein flexibility and rigidity analysis
Bramer, David; Wei, Guo-Wei
2018-02-01
Protein structural fluctuation, measured by Debye-Waller factors or B-factors, is known to correlate to protein flexibility and function. A variety of methods has been developed for protein Debye-Waller factor prediction and related applications to domain separation, docking pose ranking, entropy calculation, hinge detection, stability analysis, etc. Nevertheless, none of the current methodologies are able to deliver an accuracy of 0.7 in terms of the Pearson correlation coefficients averaged over a large set of proteins. In this work, we introduce a paradigm-shifting geometric graph model, multiscale weighted colored graph (MWCG), to provide a new generation of computational algorithms to significantly change the current status of protein structural fluctuation analysis. Our MWCG model divides a protein graph into multiple subgraphs based on interaction types between graph nodes and represents the protein rigidity by generalized centralities of subgraphs. MWCGs not only predict the B-factors of protein residues but also accurately analyze the flexibility of all atoms in a protein. The MWCG model is validated over a number of protein test sets and compared with many standard methods. An extensive numerical study indicates that the proposed MWCG offers an accuracy of over 0.8 and thus provides perhaps the first reliable method for estimating protein flexibility and B-factors. It also simultaneously predicts all-atom flexibility in a molecule.
Observations on the Darboux coordinates for rigid special geometry
Ferrara, Sergio; Ferrara, Sergio; Macia, Oscar
2006-01-01
We exploit some relations which exist when (rigid) special geometry is formulated in real symplectic special coordinates $P^I=(p^\\Lambda,q_\\Lambda), I=1,...,2n$. The central role of the real $2n\\times 2n$ matrix $M(\\Re \\mathcal{F},\\Im \\mathcal{F})$, where $\\mathcal{F} = \\partial_\\Lambda\\partial_\\Sigma F$ and $F$ is the holomorphic prepotential, is elucidated in the real formalism. The property $M\\Omega M=\\Omega$ with $\\Omega$ being the invariant symplectic form is used to prove several identities in the Darboux formulation. In this setting the matrix $M$ coincides with the (negative of the) Hessian matrix $H(S)=\\frac{\\partial^2 S}{\\partial P^I\\partial P^J}$ of a certain hamiltonian real function $S(P)$, which also provides the metric of the special K\\"ahler manifold. When $S(P)=S(U+\\bar U)$ is regarded as a "K\\"ahler potential'' of a complex manifold with coordinates $U^I=\\frac12(P^I+iZ^I)$, then it provides a K\\"ahler metric of an hyperk\\"ahler manifold which describes the hypermultiplet geometry obtained by...
A Condition Number for Non-Rigid Shape Matching
Ovsjanikov, Maks
2011-08-01
© 2011 The Author(s). Despite the large amount of work devoted in recent years to the problem of non-rigid shape matching, practical methods that can successfully be used for arbitrary pairs of shapes remain elusive. In this paper, we study the hardness of the problem of shape matching, and introduce the notion of the shape condition number, which captures the intuition that some shapes are inherently more difficult to match against than others. In particular, we make a connection between the symmetry of a given shape and the stability of any method used to match it while optimizing a given distortion measure. We analyze two commonly used classes of methods in deformable shape matching, and show that the stability of both types of techniques can be captured by the appropriate notion of a condition number. We also provide a practical way to estimate the shape condition number and show how it can be used to guide the selection of landmark correspondences between shapes. Thus we shed some light on the reasons why general shape matching remains difficult and provide a way to detect and mitigate such difficulties in practice.
Verification of the Rigidity of the Coulomb Field in Motion
Blinov, S. V.; Bulyzhenkov, I. É.
2018-06-01
Laplace, analyzing the stability of the Solar System, was the first to calculate that the velocity of the motion of force fields can significantly exceed the velocity of light waves. In electrodynamics, the Coulomb field should rigidly accompany its source for instantaneous force action in distant regions. Such rigid motion was recently inferred from experiments at the Frascati Beam Test Facility with short beams of relativistic electrons. The comments of the authors on their observations are at odds with the comments of theoreticians on retarded potentials, which motivates a detailed study of the positions of both sides. Predictions of measurements, based on the Lienard-Wiechert potentials, are used to propose an unambiguous scheme for testing the rigidity of the Coulomb field. Realization of the proposed experimental scheme could independently refute or support the assertions of the Italian physicists regarding the rigid motion of Coulomb fields and likewise the nondual field approach to macroscopic reality.
Oscillations of rigid bar in the special relativity
International Nuclear Information System (INIS)
Paiva, F.M.; Teixeira, A.F.F.
2011-12-01
In the special relativity, a rigid bar slides on herself, with a extreme oscillating harmonically. We have discovered at the movement amplitude and in the bar length, indispensable for the elimination of non physical solutions
Rigid body motion in stereo 3D simulation
International Nuclear Information System (INIS)
Zabunov, Svetoslav
2010-01-01
This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between torque and angular momentum. Consequently, the understanding of physical laws and conservation principles in free rigid body motion is hampered. This paper presents the capabilities of a 3D simulation, which aims to clarify these questions to the students, who are taught mechanics in the general physics course. The rigid body motion simulations may be observed at http://ialms.net/sim/, and are intended to complement traditional learning practices, not replace them, as the author shares the opinion that no simulation may fully resemble reality.
Resin Infusion Rigidized Inflatable Concept Development and Demonstration
National Aeronautics and Space Administration — A novel concept utilizing resin infusion to rigidize inflatable structures was developed at JSC ES. This ICA project intends to complete manufacturing of a prototype...
Re-analysis of exponential rigid-rotor astron equilibria
International Nuclear Information System (INIS)
Lovelace, R.V.; Larrabee, D.A.; Fleischmann, H.H.
1978-01-01
Previous studies of exponential rigid-rotor astron equilibria include particles which are not trapped in the self-field of the configuration. The modification of these studies required to exclude untrapped particles is derived
Rigidity theorem for Willmore surfaces in a sphere
Indian Academy of Sciences (India)
Home; Journals; Proceedings – Mathematical Sciences; Volume 126; Issue 2. Rigidity ... Center of Mathematical Sciences, Zhejiang University, Hangzhou 310027, People's Republic of China; College of Mathematics and Information Science, Jiangxi Normal University, Nanchang 330022, People's Republic of China ...
Role of Rigid Endoscopic Detorsion in the Management of Sigmoid ...
African Journals Online (AJOL)
had emergency surgery, with gangrenous bowel noted in 43 (72%) ... of any stable patient with clinical and radiological features ... peritonitis, underwent repeat rigid sigmoidoscopy. ... endoscopic detorsion was successful in all six cases.
Magnetism and magnetostriction in a degenerate rigid band
International Nuclear Information System (INIS)
Kulakowski, K.; Barbara, B.
1990-09-01
We investigate the influence of the spin-orbit coupling on the magnetic and magnetoelastic phenomena in ferromagnetic band systems. The description is within the Stoner model of a degenerate rigid band, for temperature T = O. (author). 14 refs
Stabilization of Rigid Body Dynamics by Internal and External Torques
National Research Council Canada - National Science Library
Bloch, A. M; Krishnaprasad, P. S; Marsden, J. E; Sanchez de Alvarez, G
1990-01-01
...] with quadratic feedback torques for internal rotors. We show that with such torques, the equations for the rigid body with momentum wheels are Hamiltonian with respect to a Lie-Poisson bracket structure. Further...
Hashiguchi, Koichi
2009-01-01
This book details the mathematics and continuum mechanics necessary as a foundation of elastoplasticity theory. It explains physical backgrounds with illustrations and provides descriptions of detailed derivation processes..
Droomers, Mariël; Huang, Xinyuan; Fu, Wenjie; Yang, Yong; Li, Hong; Zheng, Pinpin
2016-10-07
We aim to describe the intention to quit smoking among Chinese male smokers from different educational backgrounds and to explain this intention from their attitude, perceived social norms and self-efficacy regarding smoking cessation. Participants were recruited from workplaces and communities to reflect the occupational distribution in three cities (Shanghai, Nanning and Mudanjiang) in China. In 2013 interviews were conducted with 3676 male smokers aged 18 years and older. Multivariate logistic regression analyses calculated educational differences in the intention to quit smoking as well as the association between the intention to quit smoking and attitude, subjective norms, and self-efficacy. Bootstrapping estimated to what extent the educational disparities in the intention to quit smoking were mediated by these three determinants. No educational disparities in the intention to quit smoking within 1 or 6 months were observed among male Chinese smokers (p=0.623 and p=0.153, respectively). A less negative attitude, a higher perceived subjective norm towards smoking cessation, and a higher perceived self-efficacy to quit smoking were all associated with intention to quit (all p values theory of planned behaviour that statistically significantly mediated the differences in the intention to quit smoking (within 1 or 6 months) between the lowest educated Chinese men and the groups with lower (β=0.039, 95% CI 0.017 to 0.071 and β=0.043, 95% CI 0.019 to 0.073), higher (β=0.041, 95% CI 0.017 to 0.075 and β=0.045, 95% CI 0.019 to 0.077) and the highest education (β=0.045, 95% CI 0.019 to 0.080 and β=0.050, 95% CI 0.023 to 0.083). In order to prevent future socioeconomic disparities in smoking cessation, investment in a more stimulating social environment and norms towards smoking cessation among particularly the lowest educated Chinese men is warranted. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a
Low beta rigid mode stability criterion for an arbitrary Larmor radius plasma
International Nuclear Information System (INIS)
Berk, H.L.; Wong, H.V.
1987-05-01
The low beta flute interchange dispersion relation for rigid displacement perturbation of axisymmetric plasma equilibria with arbitrary Larmor radius particles and field line curvature, large compared to the plasma radius, is derived. The equilibrium particle orbits are characterized by two constants of motion, energy and angular momentum, and a third adiabatic invariant derived from the rapid radial motion. The Vlasov equation is integrated, assuming that the mode frequency, axial ''bounce'' frequency, and particle drift frequency are small compared to the cyclotron frequency, and it is demonstrated that the plasma response to a rigid perturbation has a universal character independent of Larmor radius. As a result the interchange instability is the same as that predicted from conventional MHD theory. However, a new prediction, more optimistic than earlier work, is found for the low density threshold of systems like Migma, which are disc-shaped, that is, the axial extent Δz is less than the radial extent r 0 . For Δz/sub r 0 / much less than 1, the stability criterion is determined by the total particle number. Whereas the older theory (Δz/sub r 0 / much greater than 1) predicted instability at about the densities achieved in actual Migma experiments, the present theory (Δz/sub r 0 / much less than 1) indicates that the experimental results were for plasmas with particle number below the interchange threshold
Pierini, Davide; Hoerold, Doreen
2014-01-01
Individuals with Acquired Brain Injury (ABI) could benefit from further cognitive rehabilitation, after they have returned home. However, a lack of specialist services to provide such rehabilitation often prevents this. This leads to reduced reintegration of patients, increased social disadvantages and ultimately, higher economic costs. 10 months post-stroke, a 69 year-old woman was discharged from an inpatient rehabilitation program and returned home with severe cognitive impairments. We describe a pilot project which provided an individualised, low cost rehabilitation program, supervised and trained by a neuropsychologist. Progress was monitored every 3 months in order to decide on continuation of the program, based on the achieved results and predicted costs. Post intervention, despite severe initial impairment, cognitive and most notably daily functioning had improved. Although the financial investment was moderately high for the family, the intervention was still considered cost-effective when compared with the required costs of care in a local non-specialist care home. Moreover, the pilot experience was used to build a "local expert team" available for other individuals requiring rehabilitation. These results encourage the development of similar local "low cost" teams in the community, to provide scientifically-grounded cognitive rehabilitation for ABI patients returning home.
On the M\\"ossbauer effect and the rigid recoil question
Davidson, Mark
2016-01-01
Various theories for the M\\"ossbauer rigid-recoil effect, which enables a crystal to absorb momentum but not appreciable energy, are compared. These suggest that the recoil may not be instantaneous, and that the recoil time could be used to distinguish between them. An experiment is proposed to measure this time. The idea is to use a small sphere whose outer surface is coated with an electrically charged M\\"ossbauer-active element, and then to measure the amount of energy lost due to Bremmsst...
Dorogovtsev, A Ya; Skorokhod, A V; Silvestrov, D S; Skorokhod, A V
1997-01-01
This book of problems is intended for students in pure and applied mathematics. There are problems in traditional areas of probability theory and problems in the theory of stochastic processes, which has wide applications in the theory of automatic control, queuing and reliability theories, and in many other modern science and engineering fields. Answers to most of the problems are given, and the book provides hints and solutions for more complicated problems.
Dependence theory via game theory
Grossi, D.; Turrini, P.
2011-01-01
In the multi-agent systems community, dependence theory and game theory are often presented as two alternative perspectives on the analysis of social interaction. Up till now no research has been done relating these two approaches. The unification presented provides dependence theory with the sort
Directory of Open Access Journals (Sweden)
Miriam eFaust
2014-07-01
Full Text Available Neurotypical individuals cope flexibly with the full range of semantic relations expressed in human language, including metaphoric relations. This impressive semantic ability may be associated with distinct and flexible patterns of hemispheric interaction, including higher right hemisphere (RH involvement for processing novel metaphors. However, this ability may be impaired in specific clinical conditions, such as Asperger syndrome and schizophrenia. The impaired semantic processing is accompanied by different patterns of hemispheric interaction during semantic processing, showing either reduced (in Asperger or excessive (in schizophrenia RH involvement. This paper interprets these individual differences using the terms Rigidity, Chaos and Integration, which describe patterns of semantic memory network states that either lead to semantic well-being or are disruptive of it. We argue that these semantic network states lie on a rigidity-chaos semantic continuum. We define these terms via network science terminology and provide network, cognitive and neural evidence to support our claim. This continuum includes LH hyper-rigid semantic memory state on one end (e.g., in persons with Asperger syndrome, and RH chaotic and over-flexible semantic memory state on the other end (e.g., in persons with schizophrenia. In between these two extremes lie different states of semantic memory structure which are related to individual differences in semantic creativity. We suggest that efficient semantic processing is achieved by semantic integration, a balance between semantic rigidity and semantic chaos. Such integration is achieved via intra-hemispheric communication. However, impairments to this well-balanced and integrated pattern of hemispheric interaction, e.g., when one hemisphere dominates the other, may lead to either semantic rigidity or semantic chaos, moving away from semantic integration and thus impairing the processing of metaphoric language.
Large scale Brownian dynamics of confined suspensions of rigid particles
Sprinkle, Brennan; Balboa Usabiaga, Florencio; Patankar, Neelesh A.; Donev, Aleksandar
2017-12-01
We introduce methods for large-scale Brownian Dynamics (BD) simulation of many rigid particles of arbitrary shape suspended in a fluctuating fluid. Our method adds Brownian motion to the rigid multiblob method [F. Balboa Usabiaga et al., Commun. Appl. Math. Comput. Sci. 11(2), 217-296 (2016)] at a cost comparable to the cost of deterministic simulations. We demonstrate that we can efficiently generate deterministic and random displacements for many particles using preconditioned Krylov iterative methods, if kernel methods to efficiently compute the action of the Rotne-Prager-Yamakawa (RPY) mobility matrix and its "square" root are available for the given boundary conditions. These kernel operations can be computed with near linear scaling for periodic domains using the positively split Ewald method. Here we study particles partially confined by gravity above a no-slip bottom wall using a graphical processing unit implementation of the mobility matrix-vector product, combined with a preconditioned Lanczos iteration for generating Brownian displacements. We address a major challenge in large-scale BD simulations, capturing the stochastic drift term that arises because of the configuration-dependent mobility. Unlike the widely used Fixman midpoint scheme, our methods utilize random finite differences and do not require the solution of resistance problems or the computation of the action of the inverse square root of the RPY mobility matrix. We construct two temporal schemes which are viable for large-scale simulations, an Euler-Maruyama traction scheme and a trapezoidal slip scheme, which minimize the number of mobility problems to be solved per time step while capturing the required stochastic drift terms. We validate and compare these schemes numerically by modeling suspensions of boomerang-shaped particles sedimented near a bottom wall. Using the trapezoidal scheme, we investigate the steady-state active motion in dense suspensions of confined microrollers, whose
Medicare Provider Data - Hospice Providers
U.S. Department of Health & Human Services — The Hospice Utilization and Payment Public Use File provides information on services provided to Medicare beneficiaries by hospice providers. The Hospice PUF...
Unifying Rigid and Soft Bodies Representation: The Sulfur Physics Engine
Directory of Open Access Journals (Sweden)
Dario Maggiorini
2014-01-01
Full Text Available Video games are (also real-time interactive graphic simulations: hence, providing a convincing physics simulation for each specific game environment is of paramount importance in the process of achieving a satisfying player experience. While the existing game engines appropriately address many aspects of physics simulation, some others are still in need of improvements. In particular, several specific physics properties of bodies not usually involved in the main game mechanics (e.g., properties useful to represent systems composed by soft bodies, are often poorly rendered by general-purpose engines. This issue may limit game designers when imagining innovative and compelling video games and game mechanics. For this reason, we dug into the problem of appropriately representing soft bodies. Subsequently, we have extended the approach developed for soft bodies to rigid ones, proposing and developing a unified approach in a game engine: Sulfur. To test the engine, we have also designed and developed “Escape from Quaoar,” a prototypal video game whose main game mechanic exploits an elastic rope, and a level editor for the game.
Use of Terrestrial Laser Scanner for Rigid Airport Pavement Management.
Barbarella, Maurizio; D'Amico, Fabrizio; De Blasiis, Maria Rosaria; Di Benedetto, Alessandro; Fiani, Margherita
2017-12-26
The evaluation of the structural efficiency of airport infrastructures is a complex task. Faulting is one of the most important indicators of rigid pavement performance. The aim of our study is to provide a new method for faulting detection and computation on jointed concrete pavements. Nowadays, the assessment of faulting is performed with the use of laborious and time-consuming measurements that strongly hinder aircraft traffic. We proposed a field procedure for Terrestrial Laser Scanner data acquisition and a computation flow chart in order to identify and quantify the fault size at each joint of apron slabs. The total point cloud has been used to compute the least square plane fitting those points. The best-fit plane for each slab has been computed too. The attitude of each slab plane with respect to both the adjacent ones and the apron reference plane has been determined by the normal vectors to the surfaces. Faulting has been evaluated as the difference in elevation between the slab planes along chosen sections. For a more accurate evaluation of the faulting value, we have then considered a few strips of data covering rectangular areas of different sizes across the joints. The accuracy of the estimated quantities has been computed too.
Use of Terrestrial Laser Scanner for Rigid Airport Pavement Management
Directory of Open Access Journals (Sweden)
Maurizio Barbarella
2017-12-01
Full Text Available The evaluation of the structural efficiency of airport infrastructures is a complex task. Faulting is one of the most important indicators of rigid pavement performance. The aim of our study is to provide a new method for faulting detection and computation on jointed concrete pavements. Nowadays, the assessment of faulting is performed with the use of laborious and time-consuming measurements that strongly hinder aircraft traffic. We proposed a field procedure for Terrestrial Laser Scanner data acquisition and a computation flow chart in order to identify and quantify the fault size at each joint of apron slabs. The total point cloud has been used to compute the least square plane fitting those points. The best-fit plane for each slab has been computed too. The attitude of each slab plane with respect to both the adjacent ones and the apron reference plane has been determined by the normal vectors to the surfaces. Faulting has been evaluated as the difference in elevation between the slab planes along chosen sections. For a more accurate evaluation of the faulting value, we have then considered a few strips of data covering rectangular areas of different sizes across the joints. The accuracy of the estimated quantities has been computed too.
Plasma surface modification of rigid contact lenses decreases bacterial adhesion.
Wang, Yingming; Qian, Xuefeng; Zhang, Xiaofeng; Xia, Wei; Zhong, Lei; Sun, Zhengtai; Xia, Jing
2013-11-01
Contact lens safety is an important topic in clinical studies. Corneal infections usually occur because of the use of bacteria-carrying contact lenses. The current study investigated the impact of plasma surface modification on bacterial adherence to rigid contact lenses made of fluorosilicone acrylate materials. Boston XO and XO2 contact lenses were modified using plasma technology (XO-P and XO2-P groups). Untreated lenses were used as controls. Plasma-treated and control lenses were incubated in solutions containing Staphylococcus aureus or Pseudomonas aeruginosa. MTT colorimetry, colony-forming unit counting method, and scanning electron microscopy were used to measure bacterial adhesion. MTT colorimetry measurements showed that the optical density (OD) values of XO-P and XO2-P were significantly lower than those of XO and XO2, respectively, after incubation with S. aureus (P lenses and to the XO2-P versus XO2 lenses incubated with S. aureus (P lenses incubated with P. aeruginosa (P lenses. Plasma surface modification can significantly decrease bacterial adhesion to fluorosilicone acrylate contact lenses. This study provides important evidence of a unique benefit of plasma technology in contact lens surface modification.
Axisymmetric scattering of an acoustical Bessel beam by a rigid fixed spheroid
Mitri, F. G.
2015-01-01
Based on the partial-wave series expansion (PWSE) method in spherical coordinates, a formal analytical solution for the acoustic scattering of a zeroth-order Bessel acoustic beam centered on a rigid fixed (oblate or prolate) spheroid is provided. The unknown scattering coefficients of the spheroid are determined by solving a system of linear equations derived for the Neumann boundary condition. Numerical results for the modulus of the backscattered pressure (\\theta = \\pi) in the near-field an...
Construction simulation analysis of 120m continuous rigid frame bridge based on Midas Civil
Shi, Jing-xian; Ran, Zhi-hong
2018-03-01
In this paper, a three-dimensional finite element model of a continuous rigid frame bridge with a main span of 120m is established by the simulation and analysis of Midas Civil software. The deflection and stress of the main beam in each construction stage of continuous beam bridge are simulated and analyzed, which provides a reliable technical guarantee for the safe construction of the bridge.
Survey of Non-Rigid Registration Tools in Medicine.
Keszei, András P; Berkels, Benjamin; Deserno, Thomas M
2017-02-01
We catalogue available software solutions for non-rigid image registration to support scientists in selecting suitable tools for specific medical registration purposes. Registration tools were identified using non-systematic search in Pubmed, Web of Science, IEEE Xplore® Digital Library, Google Scholar, and through references in identified sources (n = 22). Exclusions are due to unavailability or inappropriateness. The remaining (n = 18) tools were classified by (i) access and technology, (ii) interfaces and application, (iii) living community, (iv) supported file formats, and (v) types of registration methodologies emphasizing the similarity measures implemented. Out of the 18 tools, (i) 12 are open source, 8 are released under a permissive free license, which imposes the least restrictions on the use and further development of the tool, 8 provide graphical processing unit (GPU) support; (ii) 7 are built on software platforms, 5 were developed for brain image registration; (iii) 6 are under active development but only 3 have had their last update in 2015 or 2016; (iv) 16 support the Analyze format, while 7 file formats can be read with only one of the tools; and (v) 6 provide multiple registration methods and 6 provide landmark-based registration methods. Based on open source, licensing, GPU support, active community, several file formats, algorithms, and similarity measures, the tools Elastics and Plastimatch are chosen for the platform ITK and without platform requirements, respectively. Researchers in medical image analysis already have a large choice of registration tools freely available. However, the most recently published algorithms may not be included in the tools, yet.
Shan, Gongbing; Sust, Martin; Simard, Stephane; Bohn, Christina; Nicol, Klaus
2004-01-01
There are two main problems for biomechanists in motor learning practice. One is theory vs. experience, the other is the determination of dominative information directly helpful in the practice. This project aimed at addressing these problems from a quantitative aspect by using motion capture and biomechanical rigid body modeling. The purposes were to identify differences in the description of movements amongst motion analysists (external view), athletes (internal sight) and coaches (internal...
Gloria Gil
2008-01-01
studies by presenting some studies which adopted this point of view to carry out different types of second language related research. The main tenet of Vygotskian Theory (Vygotsky, 1978, 1986) is that human cognition is socially developed and constructed; thus, this approach offers the possibility of bringing together the cognitive and social domains, traditionally separated in human sciences. The book can be divided into two parts: a theoretical Chapter 1, and nine chapte...
Harris, Tina
2015-04-29
Grounded theory is a popular research approach in health care and the social sciences. This article provides a description of grounded theory methodology and its key components, using examples from published studies to demonstrate practical application. It aims to demystify grounded theory for novice nurse researchers, by explaining what it is, when to use it, why they would want to use it and how to use it. It should enable nurse researchers to decide if grounded theory is an appropriate approach for their research, and to determine the quality of any grounded theory research they read.
Soft-matter composites with electrically tunable elastic rigidity
International Nuclear Information System (INIS)
Shan, Wanliang; Lu, Tong; Majidi, Carmel
2013-01-01
We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium–indium–tin (Galinstan ® ) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy. (paper)
Soft-matter composites with electrically tunable elastic rigidity
Shan, Wanliang; Lu, Tong; Majidi, Carmel
2013-08-01
We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium-indium-tin (Galinstan®) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy.
Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.
Energy Technology Data Exchange (ETDEWEB)
Neilsen, Michael K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Scherzinger, William M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hinnerichs, Terry D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lo, Chi S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-06-01
Numerous experiments were performed to characterize the mechanical response of several different rigid polyurethane foams (FR3712, PMDI10, PMDI20, and TufFoam35) to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Rigid polyurethane foams were also found to be very strain-rate and temperature dependent. These foams are also rather brittle and crack when loaded to small strains in tension or to larger strains in compression. Thus, a new Unified Creep Plasticity Damage (UCPD) model was developed and implemented into SIERRA with the name Foam Damage to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments and experimental findings. Next, development of a UCPD model for rigid, polyurethane foams is described. Selection of material parameters for a variety of rigid polyurethane foams is then discussed and finite element simulations with the new UCPD model are compared with experimental results to show behavior that can be captured with this model.
Rigid external maxillary distraction and rhinoplasty for pyknodysostosis.
Varol, Altan; Sabuncuoglu, Fidan Alakus; Sencimen, Metin; Akcam, Timur; Olmez, Hüseyin; Basa, Selçuk
2011-05-01
This article reports the treatment of an 33-year-old female patient with pyknodysostosis by rigid external distraction II midface distraction system. The patient with pyknodysostosis described in this report had severe midfacial hypoplasia. Correction of this by use of routine orthognathic surgery would require osteosynthesis and bone grafting. Risk of infection and/or nonunion after such a surgical procedure was considered too great, and therefore the possibility of treatment by distraction osteogenesis of the maxilla was evaluated. The rigid external distraction II midface distraction system was used to relocate the hypoplastic maxilla at anterior-inferior projection. Distraction osteogenesis should be considered as the primary reconstructive method for maxillofacial deformities in patients with sclerosing bone dysplasias, since this is the second reported case treated successfully with rigid external distraction.
Rigidity of outermost MOTS: the initial data version
Galloway, Gregory J.
2018-03-01
In the paper Commun Anal Geom 16(1):217-229, 2008, a rigidity result was obtained for outermost marginally outer trapped surfaces (MOTSs) that do not admit metrics of positive scalar curvature. This allowed one to treat the "borderline case" in the author's work with R. Schoen concerning the topology of higher dimensional black holes (Commun Math Phys 266(2):571-576, 2006). The proof of this rigidity result involved bending the initial data manifold in the vicinity of the MOTS within the ambient spacetime. In this note we show how to circumvent this step, and thereby obtain a pure initial data version of this rigidity result and its consequence concerning the topology of black holes.
Authoritarianism, cognitive rigidity, and the processing of ambiguous visual information.
Duncan, Lauren E; Peterson, Bill E
2014-01-01
Intolerance of ambiguity and cognitive rigidity are unifying aspects of authoritarianism as defined by Adorno, Frenkel-Brunswik, Levinson, and Sanford (1982/1950), who hypothesized that authoritarians view the world in absolute terms (e.g., good or evil). Past studies have documented the relationship between authoritarianism and intolerance of ambiguity and rigidity. Frenkel-Brunswik (1949) hypothesized that this desire for absolutism was rooted in perceptual processes. We present a study with three samples that directly tests the relationship between right wing authoritarianism (RWA) and the processing of ideologically neutral but ambiguous visual stimuli. As hypothesized, in all three samples we found that RWA was related to the slower processing of visual information that required participants to recategorize objects. In a fourth sample, RWA was unrelated to speed of processing visual information that did not require recategorization. Overall, results suggest a relationship between RWA and rigidity in categorization.
Mitral stenosis due to pannus overgrowth after rigid ring annuloplasty.
Oda, Takeshi; Kato, Seiya; Tayama, Eiki; Fukunaga, Shuji; Akashi, Hidetoshi; Aoyagi, Shigeaki
2010-03-01
Although mitral stenosis (MS) due to pannus overgrowth after mitral valve repair for rheumatic mitral regurgitation (MR) is not uncommon, it is extremely rare in relation to non-rheumatic mitral regurgitation. Whilst it has been suggested that the rigid annuloplasty ring induces pannus overgrowth in the same manner as the flexible ring, to date only in cases using the flexible ring has pannus formation been confirmed by a pathological examination after redo surgery. The case is described of a woman who had undergone mitral valve repair using a 28 mm rigid ring three years previously because of non-rheumatic MR, and subsequently suffered from MS due to pannus formation over the annuloplasty ring. To the present authors' knowledge, this is the first report of MS due to pannus formation after mitral valve repair using a rigid annuloplasty ring to treat non-rheumatic MR documented at reoperation.
A concise introduction to mechanics of rigid bodies multidisciplinary engineering
Huang, L
2017-01-01
This updated second edition broadens the explanation of rotational kinematics and dynamics — the most important aspect of rigid body motion in three-dimensional space and a topic of much greater complexity than linear motion. It expands treatment of vector and matrix, and includes quaternion operations to describe and analyze rigid body motion which are found in robot control, trajectory planning, 3D vision system calibration, and hand-eye coordination of robots in assembly work, etc. It features updated treatments of concepts in all chapters and case studies. The textbook retains its comprehensiveness in coverage and compactness in size, which make it easily accessible to the readers from multidisciplinary areas who want to grasp the key concepts of rigid body mechanics which are usually scattered in multiple volumes of traditional textbooks. Theoretical concepts are explained through examples taken from across engineering disciplines and links to applications and more advanced courses (e.g. industrial rob...
Garrec, Pascal; Tavernier, Bruno; Jordan, Laurence
2005-08-01
The choice of the most suitable orthodontic wire for each stage of treatment requires estimation of the forces generated. In theory, the selection of wire sequences should initially utilize a lower flexural rigidity; thus clinicians use smaller round cross-sectional dimension wires to generate lighter forces during the preliminary alignment stage. This assessment is true for conventional alloys, but not necessarily for superelastic nickel titanium (NiTi). In this case, the flexural rigidity dependence on cross-sectional dimension differs from the linear elasticity prediction because of the martensitic transformation process. It decreases with increasing deflection and this phenomenon is accentuated in the unloading process. This behaviour should lead us to consider differently the biomechanical approach to orthodontic treatment. The present study compared bending in 10 archwires made from NiTi orthodontics alloy of two cross-sectional dimensions. The results were based on microstructural and mechanical investigations. With conventional alloys, the flexural rigidity was constant for each wire and increased largely with the cross-sectional dimension for the same strain. With NiTi alloys, the flexural rigidity is not constant and the influence of size was not as important as it should be. This result can be explained by the non-constant elastic modulus during the martensite transformation process. Thus, in some cases, treatment can begin with full-size (rectangular) wires that nearly fill the bracket slot with a force application deemed to be physiologically desirable for tooth movement and compatible with patient comfort.
Current Account Adjustment: Some New Theory and Evidence
Jiandong Ju; Shang-Jin Wei
2007-01-01
This paper aims to provide a theory of current account adjustment that generalizes the textbook version of the intertemporal approach to current account and places domestic labor market institutions at the center stage. In general, in response to a shock, an economy adjusts through a combination of a change in the composition of goods trade (i.e., intra-temporal trade channel) and a change in the current account (i.e., intertemporal trade channel). The more rigid the labor market, the slower ...
Elastic properties of rigid fiber-reinforced composites
Chen, J.; Thorpe, M. F.; Davis, L. C.
1995-05-01
We study the elastic properties of rigid fiber-reinforced composites with perfect bonding between fibers and matrix, and also with sliding boundary conditions. In the dilute region, there exists an exact analytical solution. Around the rigidity threshold we find the elastic moduli and Poisson's ratio by decomposing the deformation into a compression mode and a rotation mode. For perfect bonding, both modes are important, whereas only the compression mode is operative for sliding boundary conditions. We employ the digital-image-based method and a finite element analysis to perform computer simulations which confirm our analytical predictions.
Extremal surfaces and the rigidity of null geodesic incompleteness
International Nuclear Information System (INIS)
Silva, I P Costa e; Flores, J L
2015-01-01
An important, if relatively less well known aspect of the singularity theorems in Lorentzian geometry, is to understand how their conclusions fare upon weakening or suppression of one or more of their hypotheses. Then, theorems with modified conclusion may arise, showing that those conclusions will fail only in special cases, at least some of which may be described. These are the so-called rigidity theorems, and have many important examples in the specialized literature. In this paper, we prove rigidity results for generalized plane waves and certain globally hyperbolic spacetimes in the presence of extremal compact surfaces. (paper)
Directory of Open Access Journals (Sweden)
Gloria Gil
2008-04-01
Full Text Available studies by presenting some studies which adopted this point of view to carry out different types of second language related research. The main tenet of Vygotskian Theory (Vygotsky, 1978, 1986 is that human cognition is socially developed and constructed; thus, this approach offers the possibility of bringing together the cognitive and social domains, traditionally separated in human sciences. The book can be divided into two parts: a theoretical Chapter 1, and nine chapters that report on empirical studies carried out within the Vygotskian perspective studies by presenting some studies which adopted this point of view to carry out different types of second language related research. The main tenet of Vygotskian Theory (Vygotsky, 1978, 1986 is that human cognition is socially developed and constructed; thus, this approach offers the possibility of bringing together the cognitive and social domains, traditionally separated in human sciences. The book can be divided into two parts: a theoretical Chapter 1, and nine chapters that report on empirical studies carried out within the Vygotskian perspective
Fokas, Alexander S.; Cole, Daniel J.; Ahnert, Sebastian E.; Chin, Alex W.
2016-01-01
Amino acid networks (AANs) abstract the protein structure by recording the amino acid contacts and can provide insight into protein function. Herein, we describe a novel AAN construction technique that employs the rigidity analysis tool, FIRST, to build the AAN, which we refer to as the residue geometry network (RGN). We show that this new construction can be combined with network theory methods to include the effects of allowed conformal motions and local chemical environments. Importantly, this is done without costly molecular dynamics simulations required by other AAN-related methods, which allows us to analyse large proteins and/or data sets. We have calculated the centrality of the residues belonging to 795 proteins. The results display a strong, negative correlation between residue centrality and the evolutionary rate. Furthermore, among residues with high closeness, those with low degree were particularly strongly conserved. Random walk simulations using the RGN were also successful in identifying allosteric residues in proteins involved in GPCR signalling. The dynamic function of these residues largely remain hidden in the traditional distance-cutoff construction technique. Despite being constructed from only the crystal structure, the results in this paper suggests that the RGN can identify residues that fulfil a dynamical function. PMID:27623708
Post-Newtonian conservation laws in rigid quasilocal frames
International Nuclear Information System (INIS)
McGrath, Paul L; Chanona, Melanie; Epp, Richard J; Mann, Robert B; Koop, Michael J
2014-01-01
In recent work we constructed completely general conservation laws for energy (McGrath et al 2012 Class. Quantum Grav. 29 215012) and linear and angular momentum (Epp et al 2013 Class. Quantum Grav. 30 195019) of extended systems in general relativity based on the notion of a rigid quasilocal frame (RQF). We argued at a fundamental level that these RQF conservation laws are superior to conservation laws based on the local stress–energy–momentum tensor of matter because (1) they do not rely on spacetime symmetries and (2) they properly account for both matter and gravitational effects. Moreover, they provide simple, exact, operational expressions for fluxes of gravitational energy and linear and angular momentum. In this paper we derive the form of these laws in a general first post-Newtonian (1PN) approximation, and then apply these approximate laws to the problem of gravitational tidal interactions. We obtain formulas for tidal heating and tidal torque that agree with the literature, but without resorting to the use of pseudotensors. We describe the physical mechanism of these tidal interactions not in the traditional terms of a Newtonian gravitational force, but in terms of a much simpler and universal mechanism that is an exact, quasilocal manifestation of the equivalence principle in general relativity. As concrete examples, we look at the tidal heating of Jupiter’s moon Io and angular momentum transfer in the Earth–Moon system that causes a gradual spin-down of the Earth and recession of the Moon. In both examples we find agreement with observation. (paper)
Radiation reaction of a classical quasi-rigid extended particle
International Nuclear Information System (INIS)
Medina, Rodrigo
2006-01-01
The problem of the self-interaction of a quasi-rigid classical particle with an arbitrary spherically symmetric charge distribution is completely solved up to the first order in the acceleration. No ad hoc assumptions are made. The relativistic equations of conservation of energy and momentum in a continuous medium are used. The electromagnetic fields are calculated in the reference frame of instantaneous rest using the Coulomb gauge; in this way the troublesome power expansion is avoided. Most of the puzzles that this problem has aroused are due to the inertia of the negative pressure that equilibrates the electrostatic repulsion inside the particle. The effective mass of this pressure is -U e /(3c 2 ), where U e is the electrostatic energy. When the pressure mass is taken into account the dressed mass m turns out to be the bare mass plus the electrostatic mass m = m 0 + U e /c 2 . It is shown that a proper mechanical behaviour requires that m 0 > U e /3c 2 . This condition poses a lower bound on the radius that a particle of a given bare mass and charge may have. The violation of this condition is the reason why the Lorentz-Abraham-Dirac formula for the radiation reaction of a point charge predicts unphysical motions that run away or violate causality. Provided the mass condition is met the solutions of the exact equation of motion never run away and conform to causality and conservation of energy and momentum. When the radius is much smaller than the wavelength of the radiated fields, but the mass condition is still met, the exact expression reduces to the formula that Rohrlich (2002 Phys. Lett. A 303 307) has advocated for the radiation reaction of a quasi-point charge
International Nuclear Information System (INIS)
Schwarz, J.H.
1985-01-01
Dual string theories, initially developed as phenomenological models of hadrons, now appear more promising as candidates for a unified theory of fundamental interactions. Type I superstring theory (SST I), is a ten-dimensional theory of interacting open and closed strings, with one supersymmetry, that is free from ghosts and tachyons. It requires that an SO(eta) or Sp(2eta) gauge group be used. A light-cone-gauge string action with space-time supersymmetry automatically incorporates the superstring restrictions and leads to the discovery of type II superstring theory (SST II). SST II is an interacting theory of closed strings only, with two D=10 supersymmetries, that is also free from ghosts and tachyons. By taking six of the spatial dimensions to form a compact space, it becomes possible to reconcile the models with our four-dimensional perception of spacetime and to define low-energy limits in which SST I reduces to N=4, D=4 super Yang-Mills theory and SST II reduces to N=8, D=4 supergravity theory. The superstring theories can be described by a light-cone-gauge action principle based on fields that are functionals of string coordinates. With this formalism any physical quantity should be calculable. There is some evidence that, unlike any conventional field theory, the superstring theories provide perturbatively renormalizable (SST I) or finite (SST II) unifications of gravity with other interactions
A soft-rigid contact model of MPM for granular flow impact on retaining structures
Li, Xinpo; Xie, Yanfang; Gutierrez, Marte
2018-02-01
Protective measures against hazards associated with rapid debris avalanches include a variety of retaining structures such as rock/boulder fences, gabions, earthfill barriers and retaining walls. However, the development of analytical and numerical methods for the rational assessment of impact force generated by granular flows is still a challenge. In this work, a soft-rigid contact model is built under the coding framework of MPM which is a hybrid method with Eulerian-Lagrangian description. The soft bodies are discretized into particles (material points), and the rigid bodies are presented by rigid node-based surfaces. Coulomb friction model is used to implement the modeled contact mechanics, and a velocity-dependent friction coefficient is coupled into the model. Simulations of a physical experiment show that the peak and residual value of impact forces are well captured by the MPM model. An idealized scenario of debris avalanche flow down a hillslope and impacting on a retaining wall are analyzed using the MPM model. The calculated forces can provide a quantitative estimate from which mound design could proceed for practical implementation in the field.
A Rigid Mid-Lift-to-Drag Ratio Approach to Human Mars Entry, Descent, and Landing
Cerimele, Christopher J.; Robertson, Edward A.; Sostaric, Ronald R.; Campbell, Charles H.; Robinson, Phil; Matz, Daniel A.; Johnson, Breanna J.; Stachowiak, Susan J.; Garcia, Joseph A.; Bowles, Jeffrey V.;
2017-01-01
Current NASA Human Mars architectures require delivery of approximately 20 metric tons of cargo to the surface in a single landing. A proposed vehicle type for performing the entry, descent, and landing at Mars associated with this architecture is a rigid, enclosed, elongated lifting body shape that provides a higher lift-to-drag ratio (L/D) than a typical entry capsule, but lower than a typical winged entry vehicle (such as the Space Shuttle Orbiter). A rigid Mid-L/D shape has advantages for large mass Mars EDL, including loads management, range capability during entry, and human spaceflight heritage. Previous large mass Mars studies have focused more on symmetric and/or circular cross-section Mid-L/D shapes such as the ellipsled. More recent work has shown performance advantages for non-circular cross section shapes. This paper will describe efforts to design a rigid Mid-L/D entry vehicle for Mars which shows mass and performance improvements over previous Mid-L/D studies. The proposed concept, work to date and evolution, forward path, and suggested future strategy are described.
CFD Simulation of rigid venting of the containment of a BWR-5 Mark-II reactor
International Nuclear Information System (INIS)
Galindo G, I. F.; Vazquez B, A. K.; Velazquez E, L.; Tijerina S, F.; Tapia M, R.
2016-09-01
In conditions of prolonged loss of external energy or a severe accident, venting to the atmosphere is an alternative to prevent overpressure and release of fission products from the primary containment of a nuclear reactor. Due to the importance of flow determination through rigid vents, a computational fluid dynamics (CFD) model is proposed to verify the capacity of rigid vents in the primary containment of a boiling water reactor (BWR) under different operating conditions (pressure, temperature and compositions of the fluids). The model predicts and provides detailed information on variables such as mass flow and velocity of the venting gases. In the proposed model the primary containment gas is vented to the atmosphere via rigid vents (pipes) from the dry and wet pit. Is assumed that the container is pressurized because is in a defined scenario, and at one point the venting is open and the gas released into the atmosphere. The objective is to characterize the flow and validate the CFD model for the overpressure conditions that occur in an accident such as a LOCA, Sbo, etc. The model is implemented with Ansys-Fluent general-purpose CFD software based on the geometry of the venting ducts of the containment of a BWR. The model is developed three-dimensional and resolves at steady state for compressible flow and includes the effects of the turbulence represented by the Reynolds stress model. The CFD results are compared with the values of a one-dimensional and isentropic model for compressible flow. The relative similarity of results leads to the conclusion that the proposed CFD model can help to predict the rigid venting capacity of the containment of a BWR, however more information is required for full validation of the proposed model. (Author)
Viscoelastic materials with anisotropic rigid particles: stress-deformation behavior
Sagis, L.M.C.; Linden, van der E.
2001-01-01
In this paper we have derived constitutive equations for the stress tensor of a viscoelastic material with anisotropic rigid particles. We have assumed that the material has fading memory. The expressions are valid for slow and small deformations from equilibrium, and for systems that are nearly
Rigidity and bradykinesia reduce interlimb coordination in Parkinsonian gait
Winogrodzka, Ania; Wagenaar, Robert C.; Booij, Jan; Wolters, Eric C.
2005-01-01
Objective: To assess the influence of rigidity and bradykinesia and the extent of dopaminergic degeneration on interlimb coordination during walking in early, drug-naive patients with Parkinson's disease (PD). Design: The interlimb coordination was examined during a systematic manipulation of
Calculating ensemble averaged descriptions of protein rigidity without sampling.
Directory of Open Access Journals (Sweden)
Luis C González
Full Text Available Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.
Calculating ensemble averaged descriptions of protein rigidity without sampling.
González, Luis C; Wang, Hui; Livesay, Dennis R; Jacobs, Donald J
2012-01-01
Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG) algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG) that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars) that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.
Patient satisfaction related to rigid external distraction osteogenesis
van Eggermont, Bas; Jansma, J.; Bierman, M. W. J.; Stegenga, B.
2007-01-01
The aim of this study was to evaluate satisfaction with treatment among cleft lip and palate patients who underwent maxillary advancement using a rigid external distraction (RED) device. Nine patients (four boys, five girls), mean age 17.7 years (SD 4.0), were included in the study. Outcome measures
Short Communication: Statistical determination of the rigidity in ...
African Journals Online (AJOL)
From the graph of load against displacement, the rigidity in flexion at different moisture levels was determined from which the Young modulus was calculated. Linear regression models were fitted to the data and the results showed significant correlation coefficients between the Young modulus and moisture content for each ...
Connect-disconnect coupling for preadjusted rigid shafts
Bajkowski, F. W.; Holmberg, A.
1969-01-01
Coupling device enables a rigid shaft to be connected to or disconnected from a fixed base without disturbing the point of adjustment of the shaft in a socket or causing the shaft to rotate. The coupling consists of an externally threaded, internally slotted boss extending from the fixed base.
Rigidity percolation in dispersions with a structured viscoelastic matrix
Wilbrink, M.W.L.; Michels, M.A.J.; Vellinga, W.P.; Meijer, H.E.H.
2005-01-01
This paper deals with rigidity percolation in composite materials consisting of a dispersion of mineral particles in a microstructured viscoelastic matrix. The viscoelastic matrix in this specific case is a hydrocarbon refinery residue. In a set of model random composites the mean interparticle
Centrifuge modelling of rigid piles in soft clay
DEFF Research Database (Denmark)
Klinkvort, R.T.; Poder, M.; Truong, P.
2016-01-01
of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...
Customizable rigid head fixation for infants: technical note.
Udayakumaran, Suhas; Onyia, Chiazor U
2016-01-01
The need and advantages of rigid fixation of the head in cranial surgeries are well documented (Berryhill et al., Otolaryngol Head Neck Surg 121:269-273, 1999). Head fixation for neurosurgical procedures in infants and in early years has been a challenge and is fraught with risk. Despite the fact that pediatric pins are designed, rigid head fixation involving direct application of pins to the head of infants and slightly older children is still generally not safe (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). Yet, there are some surgeries in which some form of rigid fixation is required (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). We describe a simple technique to achieve rigid fixation of the head in infants for neurosurgical procedures. This involves applying a head band made of Plaster of Paris (POP) around the head and then applying the fixation pins of the fixation frame directly on to the POP. We have used this technique of head fixation successfully for infants with no complications.
Study of rigidity of semiconducting vanadate glasses and its ...
Indian Academy of Sciences (India)
These parameters along with the coordination number of the glasses affect the glass transition temperature. The correlation between the elastic moduli and thermal properties of these samples showed that 0.25MoO3–0.25PbO–0.5V2O5 glass is the most rigid and has an applicable glass transition temperature for coating.
Rigidity theorem for Willmore surfaces in a sphere
Indian Academy of Sciences (India)
(Math. Sci.) Vol. 126, No. 2, May 2016, pp. 253–260. c Indian Academy of Sciences. Rigidity theorem for Willmore surfaces in a sphere. HONGWEI XU1 and DENGYUN YANG2,∗. 1Center of Mathematical Sciences, Zhejiang University, Hangzhou 310027,. People's Republic of China. 2College of Mathematics and ...
Accuracy limit of rigid 3-point water models
Izadi, Saeed; Onufriev, Alexey V.
2016-08-01
Classical 3-point rigid water models are most widely used due to their computational efficiency. Recently, we introduced a new approach to constructing classical rigid water models [S. Izadi et al., J. Phys. Chem. Lett. 5, 3863 (2014)], which permits a virtually exhaustive search for globally optimal model parameters in the sub-space that is most relevant to the electrostatic properties of the water molecule in liquid phase. Here we apply the approach to develop a 3-point Optimal Point Charge (OPC3) water model. OPC3 is significantly more accurate than the commonly used water models of same class (TIP3P and SPCE) in reproducing a comprehensive set of liquid bulk properties, over a wide range of temperatures. Beyond bulk properties, we show that OPC3 predicts the intrinsic charge hydration asymmetry (CHA) of water — a characteristic dependence of hydration free energy on the sign of the solute charge — in very close agreement with experiment. Two other recent 3-point rigid water models, TIP3PFB and H2ODC, each developed by its own, completely different optimization method, approach the global accuracy optimum represented by OPC3 in both the parameter space and accuracy of bulk properties. Thus, we argue that an accuracy limit of practical 3-point rigid non-polarizable models has effectively been reached; remaining accuracy issues are discussed.
Rigid rod spaced fullerene as building block for nanoclusters
Indian Academy of Sciences (India)
By using phenylacetylene based rigid-rod linkers (PhA), we have successfully synthesized two fullerene derivatives, C60-PhA and C60-PhA-C60. The absorption spectral features of C60, as well as that of the phenylacetylene moiety are retained in the monomeric forms of these fullerene derivatives, ruling out the possibility ...
Hydrodynamics of a flexible plate between pitching rigid plates
Kim, Junyoung; Kim, Daegyoum
2017-11-01
The dynamics of a flexible plate have been studied as a model problem in swimming and flying of animals and fluid-structure interaction of plants and flags. Motivated by fish schooling and an array of sea grasses, we investigate the dynamics of a flexible plate closely placed between two pitching rigid plates. In most studies on passive deformation of the flexible plate, the plate is immersed in a uniform flow or a wavy flow. However, in this study, the flexible plate experiences periodic deformation by the oscillatory flow generated by the prescribed pitching motion of the rigid plates. In our model, the pitching axes of the rigid plates and the clamping position of the flexible plate are aligned on the same line. The flexible plate shows various responses depending on length and pitching frequency of rigid plates, thickness of a flexible plate, and free-stream velocity. To find the effect of each variable on the response of the flexible plate, amplitude of a trailing edge and modal contribution of a flapping motion are compared, and flow structure around the flexible plate is examined.
Flexible (Polyactive®) versus rigid (hydroxyapatite) dental implants
Meijer, G.J.; Heethaar, J.; Cune, M.S.; de Putter, C.; van Blitterswijk, Clemens
1997-01-01
In a beagle dog study, the peri-implant bone changes around flexible (Polyactive®) and rigid hydroxyapatite (HA) implants were investigated radiographically by quantitative digital subtraction analysis and by assessment of marginal bone height, with the aid of a computerized method. A loss of
"Mind the trap": mindfulness practice reduces cognitive rigidity.
Directory of Open Access Journals (Sweden)
Jonathan Greenberg
Full Text Available Two experiments examined the relation between mindfulness practice and cognitive rigidity by using a variation of the Einstellung water jar task. Participants were required to use three hypothetical jars to obtain a specific amount of water. Initial problems were solvable by the same complex formula, but in later problems ("critical" or "trap" problems solving was possible by an additional much simpler formula. A rigidity score was compiled through perseverance of the complex formula. In Experiment 1, experienced mindfulness meditators received significantly lower rigidity scores than non-meditators who had registered for their first meditation retreat. Similar results were obtained in randomized controlled Experiment 2 comparing non-meditators who underwent an eight meeting mindfulness program with a waiting list group. The authors conclude that mindfulness meditation reduces cognitive rigidity via the tendency to be "blinded" by experience. Results are discussed in light of the benefits of mindfulness practice regarding a reduced tendency to overlook novel and adaptive ways of responding due to past experience, both in and out of the clinical setting.
A survey on stability and rigidity results for Lie algebras
Crainic, Marius; Schätz, Florian; Struchiner, Ivan
2014-01-01
We give simple and unified proofs of the known stability and rigidity results for Lie algebras, Lie subalgebras and Lie algebra homomorphisms. Moreover, we investigate when a Lie algebra homomorphism is stable under all automorphisms of the codomain (including outer automorphisms).
21 CFR 886.5916 - Rigid gas permeable contact lens.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... against the cornea of the eye to correct vision conditions. The device is made of various materials, such...
Knowledge-In-Action: An Example with Rigid Body Motion
Da Costa, Sayonara Salvador Cabral; Moreira, Marco Antonio
2005-01-01
This paper reports the analysis of the resolution of a paper-and-pencil problem, by eight undergraduate students majoring in engineering (six) and physics (two) at the Pontifcia Universidade Catlica do Rio Grande do Sul, in Porto Alegre, Brazil. The problem concerns kinetics of a rigid body, and the analysis was done in the light of Johnson-Lairds…
Non-rigid registration by geometry-constrained diffusion
DEFF Research Database (Denmark)
Andresen, Per Rønsholt; Nielsen, Mads
1999-01-01
Assume that only partial knowledge about a non-rigid registration is given so that certain point, curves, or surfaces in one 3D image map to certain points, curves, or surfaces in another 3D image. We are facing the aperture problem because along the curves and surfaces, point correspondences...
One-dimensional rigid film acoustic metamaterials
Ma, Fuyin; Wu, Jiu Hui; Huang, Meng
2015-11-01
We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves.
One-dimensional rigid film acoustic metamaterials
International Nuclear Information System (INIS)
Ma, Fuyin; Wu, Jiu Hui; Huang, Meng
2015-01-01
We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves. (paper)
Energy Technology Data Exchange (ETDEWEB)
Jung, Hannes [DESY, Hamburg (Germany); De Roeck, Albert [CERN, Genf (Switzerland); Bartles, Jochen [Univ. Hamburg (DE). Institut fuer Theoretische Physik II] (and others)
2008-09-15
More than 100 people participated in a discussion session at the DIS08 workshop on the topic What HERA may provide. A summary of the discussion with a structured outlook and list of desirable measurements and theory calculations is given. (orig.)
International Nuclear Information System (INIS)
Jung, Hannes; De Roeck, Albert; Bartles, Jochen
2008-09-01
More than 100 people participated in a discussion session at the DIS08 workshop on the topic What HERA may provide. A summary of the discussion with a structured outlook and list of desirable measurements and theory calculations is given. (orig.)
Strategic rigidity and foresight for technology adoption among electric utilities
International Nuclear Information System (INIS)
Shah, Arsalan Nisar; Palacios, Miguel; Ruiz, Felipe
2013-01-01
The variation in the adoption of a technology as a major source of competitive advantage has been attributed to the wide-ranging strategic foresight and the integrative capability of a firm. These possible areas of competitive advantage can exist in the periphery of the firm's strategic vision and can get easily blurred as a result of rigidness and can permeate in the decision-making process of the firm. This article explores how electric utility firms with a renewable energy portfolio can become strategically rigid in terms of adoption of newer technologies. The reluctance or delay in the adoption of new technology can be characterized as strategic rigidness, brought upon as a result of a firm's core competence or core capability in the other, more conventional technology arrangement. This paper explores the implications of such rigidness on the performance of a firm and consequently on the energy eco-system. The paper substantiates the results by emphasizing the case of Iberdrola S.A., an incumbent firm as a wind energy developer and its adoption decision behavior. We illustrate that the very routines that create competitive advantage for firms in the electric utility industry are vulnerable as they might also develop as sources of competitive disadvantage, when firms confront environmental change and uncertainty. - Highlights: • Present a firm-level perspective on technology adoption behavior among electric utilities. • Firms with mature technology can become rigid towards newer technologies. • Case study analysis of a major electric utility firm. • Implications of ‘technology rigidness’ on the energy eco-system
Matrix rigidity regulates cancer cell growth and cellular phenotype.
Directory of Open Access Journals (Sweden)
Robert W Tilghman
2010-09-01
Full Text Available The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness of the microenvironment and how this response varies among cancer cell lines.In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: "rigidity dependent" (those which show an increase in cell growth as extracellular rigidity is increased, and "rigidity independent" (those which grow equally on both soft and stiff substrates. Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug.These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models.
Matrix Rigidity Regulates Cancer Cell Growth and Cellular Phenotype
Tilghman, Robert W.; Cowan, Catharine R.; Mih, Justin D.; Koryakina, Yulia; Gioeli, Daniel; Slack-Davis, Jill K.; Blackman, Brett R.; Tschumperlin, Daniel J.; Parsons, J. Thomas
2010-01-01
Background The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness) of the microenvironment and how this response varies among cancer cell lines. Methodology/Principal Findings In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: “rigidity dependent” (those which show an increase in cell growth as extracellular rigidity is increased), and “rigidity independent” (those which grow equally on both soft and stiff substrates). Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug. Conclusions/Significance These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models. PMID:20886123
Could information theory provide an ecological theory of sensory processing?
Atick, Joseph J
2011-01-01
The sensory pathways of animals are well adapted to processing a special class of signals, namely stimuli from the animal's environment. An important fact about natural stimuli is that they are typically very redundant and hence the sampled representation of these signals formed by the array of sensory cells is inefficient. One could argue for some animals and pathways, as we do in this review, that efficiency of information representation in the nervous system has several evolutionary advantages. Consequently, one might expect that much of the processing in the early levels of these sensory pathways could be dedicated towards recoding incoming signals into a more efficient form. In this review, we explore the principle of efficiency of information representation as a design principle for sensory processing. We give a preliminary discussion on how this principle could be applied in general to predict neural processing and then discuss concretely some neural systems where it recently has been shown to be successful. In particular, we examine the fly's LMC coding strategy and the mammalian retinal coding in the spatial, temporal and chromatic domains.
Theory of fundamental interactions
International Nuclear Information System (INIS)
Pestov, A.B.
1992-01-01
In the present article the theory of fundamental interactions is derived in a systematic way from the first principles. In the developed theory there is no separation between space-time and internal gauge space. Main equations for basic fields are derived. In is shown that the theory satisfies the correspondence principle and gives rise to new notions in the considered region. In particular, the conclusion is made about the existence of particles which are characterized not only by the mass, spin, charge but also by the moment of inertia. These are rotating particles, the particles which represent the notion of the rigid body on the microscopical level and give the key for understanding strong interactions. The main concepts and dynamical laws for these particles are formulated. The basic principles of the theory may be examined experimentally not in the distant future. 29 refs
On the twisted chiral potential in 2d and the analogue of rigid special geometry for 4-folds
Kaste, P
1999-01-01
We discuss how to obtain an N=(2,2) supersymmetric SU(3) gauge theory in two dimensions via geometric engineering from a Calabi-Yau 4-fold and compute its non-perturbative twisted chiral potential. The relevant compact part of the 4-fold geometry consists of two intersecting P^1's fibered over P^2. The rigid limit of the local mirror of this geometry is a complex surface that generalizes the Seiberg-Witten curve and on which there exist two holomorphic 2-forms. These stem from the same meromorphic 2-form as derivatives w.r.t. the two moduli, respectively. The middle periods of this meromorphic form give directly the twisted chiral potential. The explicit computation of these and of the four-point Yukawa couplings allows for a non-trivial test of the analogue of rigid special geometry for a 4-fold with several moduli.
The general problem of the motion of coupled rigid bodies about a fixed point
Leimanis, Eugene
1965-01-01
In the theory of motion of several coupled rigid bodies about a fixed point one can distinguish three basic ramifications. 1. The first, the so-called classical direction of investigations, is concerned with particular cases of integrability ot the equations of motion of a single rigid body about a fixed point,1 and with their geo metrical interpretation. This path of thought was predominant until the beginning of the 20th century and its most illustrious represen tatives are L. EULER (1707-1783), J L. LAGRANGE (1736-1813), L. POINSOT (1777-1859), S. V. KOVALEVSKAYA (1850-1891), and others. Chapter I of the present monograph intends to reflect this branch of investigations. For collateral reading on the general questions dealt with in this chapter the reader is referred to the following textbooks and reports: A. DOMOGAROV [1J, F. KLEIN and A. SOMMERFELD [11, 1 , 1 J, A. G. 2 3 GREENHILL [10J, A. GRAY [1J, R. GRAMMEL [4 J, E. J. ROUTH [21' 2 , 1 2 31' 32J, J. B. SCARBOROUGH [1J, and V. V. GOLUBEV [1, 2J.
Homogenization for rigid suspensions with random velocity-dependent interfacial forces
Gorb, Yuliya
2014-12-01
We study suspensions of solid particles in a viscous incompressible fluid in the presence of random velocity-dependent interfacial forces. The flow at a small Reynolds number is modeled by the Stokes equations, coupled with the motion of rigid particles arranged in a periodic array. The objective is to perform homogenization for the given suspension and obtain an equivalent description of a homogeneous (effective) medium, the macroscopic effect of the interfacial forces and the effective viscosity are determined using the analysis on a periodicity cell. In particular, the solutions uωε to a family of problems corresponding to the size of microstructure ε and describing suspensions of rigid particles with random surface forces imposed on the interface, converge H1-weakly as ε→0 a.s. to a solution of a Stokes homogenized problem, with velocity dependent body forces. A corrector to a homogenized solution that yields a strong H1-convergence is also determined. The main technical construction is built upon the Γ-convergence theory. © 2014 Elsevier Inc.
Fast and anisotropic flexibility-rigidity index for protein flexibility and fluctuation analysis
Energy Technology Data Exchange (ETDEWEB)
Opron, Kristopher [Department of Biochemistry and Molecular Biology, Michigan State University, Michigan 48824 (United States); Xia, Kelin [Department of Mathematics, Michigan State University, Michigan 48824 (United States); Wei, Guo-Wei, E-mail: wei@math.msu.edu [Department of Biochemistry and Molecular Biology, Michigan State University, Michigan 48824 (United States); Department of Mathematics, Michigan State University, Michigan 48824 (United States); Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824 (United States)
2014-06-21
Protein structural fluctuation, typically measured by Debye-Waller factors, or B-factors, is a manifestation of protein flexibility, which strongly correlates to protein function. The flexibility-rigidity index (FRI) is a newly proposed method for the construction of atomic rigidity functions required in the theory of continuum elasticity with atomic rigidity, which is a new multiscale formalism for describing excessively large biomolecular systems. The FRI method analyzes protein rigidity and flexibility and is capable of predicting protein B-factors without resorting to matrix diagonalization. A fundamental assumption used in the FRI is that protein structures are uniquely determined by various internal and external interactions, while the protein functions, such as stability and flexibility, are solely determined by the structure. As such, one can predict protein flexibility without resorting to the protein interaction Hamiltonian. Consequently, bypassing the matrix diagonalization, the original FRI has a computational complexity of O(N{sup 2}). This work introduces a fast FRI (fFRI) algorithm for the flexibility analysis of large macromolecules. The proposed fFRI further reduces the computational complexity to O(N). Additionally, we propose anisotropic FRI (aFRI) algorithms for the analysis of protein collective dynamics. The aFRI algorithms permit adaptive Hessian matrices, from a completely global 3N × 3N matrix to completely local 3 × 3 matrices. These 3 × 3 matrices, despite being calculated locally, also contain non-local correlation information. Eigenvectors obtained from the proposed aFRI algorithms are able to demonstrate collective motions. Moreover, we investigate the performance of FRI by employing four families of radial basis correlation functions. Both parameter optimized and parameter-free FRI methods are explored. Furthermore, we compare the accuracy and efficiency of FRI with some established approaches to flexibility analysis, namely
Directory of Open Access Journals (Sweden)
Yu. V. Vasilevich
2016-01-01
Full Text Available Virtual testing of portal machine tool has been carried out with the help of finite elements method (FEM. Static, modal and harmonic analyses have been made for a heavy planer. The paper reveals influence of concrete filler on machine tool dynamic flexibility. A peculiar feature of the simulation is concrete filling of a high-level transverse beam. Such approach oes look a typical one for machine-tool industry. Concrete has been considered as generalized material in two variants. It has been established that concrete application provides approximately 3-fold increase in machine tool rigidity per each coordinate. In this regard it is necessary to arrange closure of rigidity contour by filling all the cavities inside of the portal. Modal FEA makes it possible to determine that concrete increases comparatively weakly (1.3–1.4-fold frequencies of resonance modes. Frequency of the lowest mode rises only from 30.25 to 42.86 Hz. The following most active whole-machine eigenmodes have been revealed in the paper: “Portal pecking”, “Parallelogram” and “Traverse pecking”. In order to restrain the last mode it is necessary to carry out concrete filling of the traverse, in particular. Frequency-response characteristics and curves of dynamic rigidity for a spindle have been plotted for 0–150 Hz interval while using harmonic FEM. It has been determined that concrete increases dynamic machine tool rigidity by 2.5–3.5-fold. The effect is obtained even in the case when weakly damping concrete (2 % is used. This is due to distribution of vibrational energy flow along concrete and along cast iron as well. Thus energy density and vibration amplitudes must decrease. The paper shows acceptability for internal reinforcement of high-level machine tool parts (for example, portal traverses and fillers are applied for this purpose. Traverse weighting is compensated by additional torsional, shear and bending rigidity. The machine tool obtains the
Recursion theory computational aspects of definability
Chong, Chi Tat
2015-01-01
This monograph presents recursion theory from a generalized and largely global point of view. A major theme is the study of the structures of degrees arising from two key notions of reducibility, the Turing degrees and the hyperdegrees, using ideas and techniques beyond those of classical recursion theory. These include structure theory, hyperarithmetic determinacy and rigidity, basis theorems, independence results on Turing degrees, as well as applications to higher randomness.
Pediatric mandibular fractures treated by rigid internal fixation.
Wong, G B
1993-09-01
Mandibular fractures in the pediatric patient population are relatively uncommon. These patients present with their own unique treatment requirements. Most fractures have been treated conservatively by dental splints. Closed reduction techniques with maxillomandibular fixation (MMF) in very young children can pose several concerns, including cooperation, compliance and adequate nutritional intake. Rigid internal fixation of unstable mandibular fractures using miniplates and screws circumvents the need for MMF and allows immediate jaw mobilization. At major pediatric trauma institutions, there has been an increasing trend toward the use of this treatment when open reduction is necessary. This article presents a report of a five-year-old child who presented with bilateral mandibular fractures and was treated by rigid internal fixation and immediate mandibular mobilization.
Handedness in shearing auxetics creates rigid and compliant structures
Lipton, Jeffrey Ian; MacCurdy, Robert; Manchester, Zachary; Chin, Lillian; Cellucci, Daniel; Rus, Daniela
2018-05-01
In nature, repeated base units produce handed structures that selectively bond to make rigid or compliant materials. Auxetic tilings are scale-independent frameworks made from repeated unit cells that expand under tension. We discovered how to produce handedness in auxetic unit cells that shear as they expand by changing the symmetries and alignments of auxetic tilings. Using the symmetry and alignment rules that we developed, we made handed shearing auxetics that tile planes, cylinders, and spheres. By compositing the handed shearing auxetics in a manner inspired by keratin and collagen, we produce both compliant structures that expand while twisting and deployable structures that can rigidly lock. This work opens up new possibilities in designing chemical frameworks, medical devices like stents, robotic systems, and deployable engineering structures.
Rigid inclusions-Comparison between analytical and numerical methods
International Nuclear Information System (INIS)
Gomez Perez, R.; Melentijevic, S.
2014-01-01
This paper compares different analytical methods for analysis of rigid inclusions with finite element modeling. First of all, the load transfer in the distribution layer is analyzed for its different thicknesses and different inclusion grids to define the range between results obtained by analytical and numerical methods. The interaction between the soft soil and the inclusion in the estimation of settlements is studied as well. Considering different stiffness of the soft soil, settlements obtained analytical and numerically are compared. The influence of the soft soil modulus of elasticity on the neutral point depth was also performed by finite elements. This depth has a great importance for the definition of the total length of rigid inclusion. (Author)
Rigidity of complete noncompact bach-flat n-manifolds
Chu, Yawei; Feng, Pinghua
2012-11-01
Let (Mn,g) be a complete noncompact Bach-flat n-manifold with the positive Yamabe constant and constant scalar curvature. Assume that the L2-norm of the trace-free Riemannian curvature tensor R∘m is finite. In this paper, we prove that (Mn,g) is a constant curvature space if the L-norm of R∘m is sufficiently small. Moreover, we get a gap theorem for (Mn,g) with positive scalar curvature. This can be viewed as a generalization of our earlier results of 4-dimensional Bach-flat manifolds with constant scalar curvature R≥0 [Y.W. Chu, A rigidity theorem for complete noncompact Bach-flat manifolds, J. Geom. Phys. 61 (2011) 516-521]. Furthermore, when n>9, we derive a rigidity result for R<0.
Rigid-beam model of a high-efficiency magnicon
International Nuclear Information System (INIS)
Rees, D.E.; Tallerico, P.J.; Humphries, S.J. Jr.
1993-01-01
The magnicon is a new type of high-efficiency deflection-modulated amplifier developed at the Institute of Nuclear Physics in Novosibirsk, Russia. The prototype pulsed magnicon achieved an output power of 2.4 MW and an efficiency of 73% at 915 MHz. This paper presents the results of a rigid-beam model for a 700-MHz, 2.5-MW 82%-efficient magnicon. The rigid-beam model allows for characterization of the beam dynamics by tracking only a single electron. The magnicon design presented consists of a drive cavity; passive cavities; a pi-mode, coupled-deflection cavity; and an output cavity. It represents an optimized design. The model is fully self-consistent, and this paper presents the details of the model and calculated performance of a 2.5-MW magnicon
MRS2016: Rigid Moon Rotation Series in the Relativistic Approximation
Pashkevich, V. V.
2017-03-01
The rigid Moon rotation problem is studied for the relativistic (kinematical) case, in which the geodetic perturbations in the Moon rotation are taken into account. As the result of this research the high-precision Moon Rotation Series MRS2016 in the relativistic approximation was constructed for the first time and the discrepancies between the high-precision numerical and the semi-analytical solutions of the rigid Moon rotation were investigated with respect to the fixed ecliptic of epoch J2000, by the numerical and analytical methods. The residuals between the numerical solution and MRS2016 in the perturbing terms of the physical librations do not exceed 80 mas and 10 arc seconds over 2000 and 6000 years, respectively.
Partial ring currents and cosmic ray magnetic cutoff rigidity variations
International Nuclear Information System (INIS)
Arens, M.
1978-01-01
A short introduction on cosmic ray modulation and a description of the magnetosphere, and of some physical processes occurring within its boundaries are presented. 20 geomagnetic storms are analysed together with the cosmic ray intensities during these storms as measured by Neutron Monitors. Using a semi-empirical method, the variations in the magnetic cutoff rigidity for the mountain stations Pic du Midi and Jungfraujoch are deduced. These stations are the most sensitive for measuring these variations. The analysis shows that all analyzed storms have an asymmetric development phase. Often the asymmetry even continues during part of the recovery phase. It is shown that variations in magnetic cutoff rigidity occur only during the asymmetric phase of the storm. The largest variations are found when the cosmic ray station is located in the late afternoon-midnight sector. (Auth.)
A Future of Communication Theory: Systems Theory.
Lindsey, Georg N.
Concepts of general systems theory, cybernetics and the like may provide the methodology for communication theory to move from a level of technology to a level of pure science. It was the purpose of this paper to (1) demonstrate the necessity of applying systems theory to the construction of communication theory, (2) review relevant systems…
A rigid lamb syndrome in sheep in Rhodesia.
Rudert, C P; Lawrence, J A; Foggin, C; Barlow, R M
1978-04-29
A syndrome characterised by the birth of lambs with varying degrees of rigidity of the limbs and spine has been encountered on several occasions in Rhodesia. Outbreaks have occurred in autumn-born lambs from Dorper ewes grazing heavily fertilised Star grass cv No 2 (Cynodon aethiopicus) pastures. The condition appears to be exacerbated by the application of sulphur to the pasture and is partly prevented by the administration of selenium and vitamin E to the ewes before lambing. The aetiology is unknown.
Nonlinear dynamics mathematical models for rigid bodies with a liquid
Lukovsky, Ivan A
2015-01-01
This book is devoted to analytically approximate methods in the nonlinear dynamics of a rigid body with cavities partly filled by liquid. It combines several methods and compares the results with experimental data. It is useful for experienced and early-stage readers interested in analytical approaches to fluid-structure interaction problems, the fundamental mathematical background and modeling the dynamics of such complex mechanical systems.
Steady fall of a rigid body in viscous fluid
Czech Academy of Sciences Publication Activity Database
Nečasová, Šárka
2005-01-01
Roč. 63, Sp. Is. (2005), s. 2113-2119 ISSN 0362-546X. [Invited Talks from the Fourth World Congress of Nonlinear Analysts (WCNA 2004). Orlando , 30.7.2004-7.8.2004] R&D Projects: GA ČR(CZ) GA201/02/0684 Institutional research plan: CEZ:AV0Z1019905 Keywords : steady fall * rigid body * viscous fluid Subject RIV: BA - General Mathematics Impact factor: 0.519, year: 2005
NOLB: Nonlinear Rigid Block Normal Mode Analysis Method
Hoffmann , Alexandre; Grudinin , Sergei
2017-01-01
International audience; We present a new conceptually simple and computationally efficient method for nonlinear normal mode analysis called NOLB. It relies on the rotations-translations of blocks (RTB) theoretical basis developed by Y.-H. Sanejouand and colleagues. We demonstrate how to physically interpret the eigenvalues computed in the RTB basis in terms of angular and linear velocities applied to the rigid blocks and how to construct a nonlinear extrapolation of motion out of these veloci...
Oscillations of manometric tubular springs with rigid end
Cherentsov, D. A.; Pirogov, S. P.; Dorofeev, S. M.; Ryabova, Y. S.
2018-05-01
The paper presents a mathematical model of attenuating oscillations of manometric tubular springs (MTS) taking into account the rigid tip. The dynamic MTS model is presented in the form of a thin-walled curved rod oscillating in the plane of curvature of the central axis. Equations for MTS oscillations are obtained in accordance with the d’Alembert principle in projections onto the normal and tangential. The Bubnov-Galerkin method is used to solve the equations obtained.
On Polya's inequality for torsional rigidity and first Dirichlet eigenvalue
Berg, M. van den; Ferone, V.; Nitsch, C.; Trombetti, C.
2016-01-01
Let $\\Omega$ be an open set in Euclidean space with finite Lebesgue measure $|\\Omega|$. We obtain some properties of the set function $F:\\Omega\\mapsto \\R^+$ defined by $$ F(\\Omega)=\\frac{T(\\Omega)\\lambda_1(\\Omega)}{|\\Omega|} ,$$ where $T(\\Omega)$ and $\\lambda_1(\\Omega)$ are the torsional rigidity and the first eigenvalue of the Dirichlet Laplacian respectively. We improve the classical P\\'olya bound $F(\\Omega)\\le 1,$ and show that $$F(\\Omega)\\le 1- \
Polyester Polyols from Waste PET Bottles for Polyurethane Rigid Foams
Evtimova, Rozeta; Lozeva, Yordanka; Schmidt, Karl-Heinz; Wotzka, Michael; Wagner, Peter; Behrendt, Gerhard
2003-01-01
This paper describes a modified process to produce polyester polyols from PET wastes derived from the “bottle fraction residue” of the German Dual System (DSD) [11] employing a waste oligoester condensate of the polyesterification process with the addition of some glycols of longer chain and occasional modification with further dicarboxylic acids to produce polyester polyols of a broad range of properties which are further reacted to form polyurethane or polyisocyanurate rigid foams for insul...
Modyfication of the Rigid Polyurethane-Polyisocyanurate Foams
Bogusław Czupryński; Joanna Liszkowska; Joanna Paciorek-Sadowska
2014-01-01
The effect of polyethylene glycol 1500 on physicomechanical properties of rigid polyurethane-polyisocyanurate (PUR-PIR) foams has been studied. It was found that application of polyethylene glycol 1500 for synthesis of foams in amount from 0% to 20% w/w had an effect on reduction of brittleness and softening point, while the greater the increase in compressive strength the higher its content in foam composition was. Wastes from production of these foams were ground and subjected to glycolysis...
International Nuclear Information System (INIS)
Jiang, Bin; Song, Hongwei; Yang, Minghui; Guo, Hua
2016-01-01
The quantum dynamics of water dissociative chemisorption on the rigid Ni(111) surface is investigated using a recently developed nine-dimensional potential energy surface. The quantum dynamical model includes explicitly seven degrees of freedom of D 2 O at fixed surface sites, and the final results were obtained with a site-averaging model. The mode specificity in the site-specific results is reported and analyzed. Finally, the approximate sticking probabilities for various vibrationally excited states of D 2 O are obtained considering surface lattice effects and formally all nine degrees of freedom. The comparison with experiment reveals the inaccuracy of the density functional theory and suggests the need to improve the potential energy surface.
Aboumoussa, Walid
2014-01-01
Structures placed on hillsides often present a number of challenges and a limited number of economical choices for site design. An option sometimes employed is to use the building frame as a retaining element, comprising a Rigidly Framed Earth Retaining Structure (RFERS). The relationship between temperature and earth pressure acting on RFERS, is explored in this monograph through a 4.5 year monitoring program of a heavily instrumented in service structure. The data indicated that the coefficient of earth pressure behind the monitored RFERS had a strong linear correlation with temperature. The study also revealed that thermal cycles, rather than lateral earth pressure, were the cause of failure in many structural elements. The book demonstrates that depending on the relative stiffness of the retained soil mass and that of the structural frame, the developed lateral earth pressure, during thermal expansion, can reach magnitudes several times larger than those determined using classical earth pressure theories....
On the monoaxial stabilization of a rigid body under vanishing restoring torque
Aleksandrov, A. Yu.; Aleksandrova, E. B.; Tikhonov, A. A.
2018-05-01
The problem of monoaxial stabilization of a rigid body is studied. It is assumed that a linear time-invariant dissipative torque and a time-varying restoring torque vanishing as time increases act on the body. Both the case of linear restoring torque and that of essentially nonlinear one are considered. With the aid of the decomposition method, conditions are obtained under which we can guarantee the asymptotic stability of an equilibrium position of the body despite the vanishing of the restoring torque. A numerical simulation is provided to demonstrate the effectiveness of our theoretical results.
Measure Guideline: Incorporating Thick Layers of Exterior Rigid Insulation on Walls
Energy Technology Data Exchange (ETDEWEB)
Lstiburek, Joseph [Building Science Corporation, Westford, MA (United States); Baker, Peter [Building Science Corporation, Westford, MA (United States)
2015-04-01
This measure guideline provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ inches and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: fundamental building science principles relating to the use of exterior insulation on wall assemblies; design principles for tailoring this use to the specific project goals and requirements; and construction detailing to increase understanding about implementing the various design elements.
Measure Guideline. Incorporating Thick Layers of Exterior Rigid Insulation on Walls
Energy Technology Data Exchange (ETDEWEB)
Lstiburek, Joseph [Building Science Corporation, Westford, MA (United States); Baker, Peter [Building Science Corporation, Westford, MA (United States)
2015-04-09
This measure guideline, written by the U.S. Department of Energy’s Building America team Building Science Corporation, provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ in. and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: (1) fundamental building science principles relating to the use of exterior insulation on wall assemblies; (2) design principles for tailoring this use to the specific project goals and requirements; and (3) construction detailing to increase understanding about implementing the various design elements.
LENUS (Irish Health Repository)
Ahmad, Nasir Zaheer
2012-06-01
Rigid sigmoidoscopy is sometimes performed at first presentation in colorectal clinics. We assessed the feasibility of flexible sigmoidoscopy in similar situations by comparing it with rigid sigmoidoscopy as a first investigative tool.
Chiral Orientation of Skeletal Muscle Cells Requires Rigid Substrate
Directory of Open Access Journals (Sweden)
Ninghao Zhu
2017-06-01
Full Text Available Reconstitution of tissue morphology with inherent left–right (LR asymmetry is essential for tissue/organ functions. For skeletal muscle, the largest tissue in mammalian organisms, successful myogenesis requires the regulation of the LR asymmetry to form the appropriate muscle alignment. However, the key factor for reproducing the LR asymmetry of skeletal tissues in a controllable, engineering context remains largely unknown. Recent reports indicate that cell chirality may underlie the LR development in tissue morphogenesis. Here, we report that a rigid substrate is required for the chirality of skeletal muscle cells. By using alternating micropatterned cell-adherent and cell-repellent stripes on a rigid substrate, we found that C2C12 skeletal muscle myoblasts exhibited a unidirectional tilted orientation with respect to the stripe boundary. Importantly, such chiral orientation was reduced when soft substrates were used instead. In addition, we demonstrated the key role of actin stress fibers in the formation of the chiral orientation. This study reveals that a rigid substrate is required for the chiral pattern of myoblasts, paving the way for reconstructing damaged muscle tissue with inherent LR asymmetry in the future.
Field dependent cosmic ray streaming at high rigidities
International Nuclear Information System (INIS)
Swinson, D.B.
1976-01-01
Data from underground μ meson telescopes at depths of 25, 40, and 80 mwe covering the period 1965--1973 have been analyzed as a function of interplanetary magnetic field direction. Cosmic ray streaming both in and perpendicular to the ecliptic plane, with directions dependent on the sense of the interplanetary magnetic field, is observed throughout the period at all depths. The field dependent streaming in the ecliptic plane exhibits some variability in amplitude and phase but contains a component in the direction perpendicular to the interplanetary magnetic field direction which is consistent with B x delN streaming due to a perpendicular cosmic ray density gradient pointing southward (higher density below the ecliptic plane than above it). In the case of the field dependent streaming perpendicular to the ecliptic plane the direction of the streaming has remained remarkably consistent over the 9-year period. One possible source of this streaming is B x delN streaming due to a radial heliocentric cosmic ray density gradient; this possibility is discussed along with other possible sources. There does not appear to be an obvious variation in the amplitude of the field dependent streaming either in or perpendicular to the ecliptic plane with increasing rigidity; both effects are still apparent at rigidities well above the 52-GV threshold rigidity of the Socorro 80-mwe telescope. The amplitudes of both anisotropies appear larger at solar maximum than at solar minimum
Rigid Body Energy Minimization on Manifolds for Molecular Docking.
Mirzaei, Hanieh; Beglov, Dmitri; Paschalidis, Ioannis Ch; Vajda, Sandor; Vakili, Pirooz; Kozakov, Dima
2012-11-13
Virtually all docking methods include some local continuous minimization of an energy/scoring function in order to remove steric clashes and obtain more reliable energy values. In this paper, we describe an efficient rigid-body optimization algorithm that, compared to the most widely used algorithms, converges approximately an order of magnitude faster to conformations with equal or slightly lower energy. The space of rigid body transformations is a nonlinear manifold, namely, a space which locally resembles a Euclidean space. We use a canonical parametrization of the manifold, called the exponential parametrization, to map the Euclidean tangent space of the manifold onto the manifold itself. Thus, we locally transform the rigid body optimization to an optimization over a Euclidean space where basic optimization algorithms are applicable. Compared to commonly used methods, this formulation substantially reduces the dimension of the search space. As a result, it requires far fewer costly function and gradient evaluations and leads to a more efficient algorithm. We have selected the LBFGS quasi-Newton method for local optimization since it uses only gradient information to obtain second order information about the energy function and avoids the far more costly direct Hessian evaluations. Two applications, one in protein-protein docking, and the other in protein-small molecular interactions, as part of macromolecular docking protocols are presented. The code is available to the community under open source license, and with minimal effort can be incorporated into any molecular modeling package.
Crack identification for rigid pavements using unmanned aerial vehicles
Bahaddin Ersoz, Ahmet; Pekcan, Onur; Teke, Turker
2017-09-01
Pavement condition assessment is an essential piece of modern pavement management systems as rehabilitation strategies are planned based upon its outcomes. For proper evaluation of existing pavements, they must be continuously and effectively monitored using practical means. Conventionally, truck-based pavement monitoring systems have been in-use in assessing the remaining life of in-service pavements. Although such systems produce accurate results, their use can be expensive and data processing can be time consuming, which make them infeasible considering the demand for quick pavement evaluation. To overcome such problems, Unmanned Aerial Vehicles (UAVs) can be used as an alternative as they are relatively cheaper and easier-to-use. In this study, we propose a UAV based pavement crack identification system for monitoring rigid pavements’ existing conditions. The system consists of recently introduced image processing algorithms used together with conventional machine learning techniques, both of which are used to perform detection of cracks on rigid pavements’ surface and their classification. Through image processing, the distinct features of labelled crack bodies are first obtained from the UAV based images and then used for training of a Support Vector Machine (SVM) model. The performance of the developed SVM model was assessed with a field study performed along a rigid pavement exposed to low traffic and serious temperature changes. Available cracks were classified using the UAV based system and obtained results indicate it ensures a good alternative solution for pavement monitoring applications.
Green waste cooking oil-based rigid polyurethane foam
Enderus, N. F.; Tahir, S. M.
2017-11-01
Polyurethane is a versatile polymer traditionally prepared using petroleum-based raw material. Petroleum, however, is a non-renewable material and polyurethane produced was found to be non-biodegradable. In quest for a more environmentally friendly alternative, wastecooking oil, a highly abundant domestic waste with easily derivatized structure, is a viable candidate to replace petroleum. In this study,an investigation to determine physical and chemical properties of rigid polyurethane (PU) foam from waste cooking oil (WCO) was carried out. WCO was first adsorbed by using coconut husk activated carbon adsorbent prior to be used for polyol synthesis. The purified WCO was then used to synthesize polyol via transesterification reaction to yield alcohol groups in the WCO chains structure. Finally, the WCO-based polyol was used to prepare rigid PU foam. The optimum formulation for PU formation was found to be 90 polyol: 60 glycerol: 54 water: 40 diethanolamine: 23 diisocyanate. The rigid PU foam has density of 208.4 kg/m3 with maximum compressive strength and capability to receive load at 0.03 MPa and 0.09 kN, respectively. WCO-based PU can potentially be used to replace petroleum-based PU as house construction materials such as insulation panels.
Artificial semi-rigid tissue sensitized with natural pigments: Effect of photon radiations
Directory of Open Access Journals (Sweden)
Adnan Jaradat
2011-01-01
Full Text Available Background: A new approach for evaluating the optical penetration depth and testing its validity with Monte Carlo simulations and Kubelka-Munk theory is used for artificial semi-rigid tissue sensitized with natural pigments. Photodynamic therapy is a promising cancer treatment in which a photosensitizing drug concentrates in malignant cells and is activated by visible light at certain wavelength. Materials and Methods: Cheap artificial semi-rigid tissue incorporated with scattering and absorbing materials along with some other composites comparable to normal human tissue has been performed. The optical parameters as measured with different conditions and calculated with various techniques are investigated. Results: The probability of interaction of light with tissue is very high when exposed to light in presence of Cichorium pumilum and RBCs followed by photohemolysis or/and photodegradation. The optical penetration depth calculated by linear absorption coefficient ranges from 0.63 to 2.85 mm is found to be comparable to those calculated using Kubelka-Munk theory or Monte Carlo simulation (range from 0.78 to 2.42 mm. The ratio of absorption to the scattering is independent of thickness and decreases with increasing irradiation time. Moreover, the optical parameters as well as their ratios are in very good agreement in the two approaches of calculation. The values of absorption and scattering coefficients are independent of thickness. Furthermore, the average photon ranges in the samples containing no scattering and absorbing materials are about three times greater than those samples containing scattering materials. Conclusion: Our results suggest that light propagation with optical properties presented in this work could be applicable in diagnostic and therapeutic of the human biological tissue for photodynamic therapy.
Bang-Bang Practical Stabilization of Rigid Bodies
Serpelloni, Edoardo
In this thesis, we study the problem of designing a practical stabilizer for a rigid body equipped with a set of actuators generating only constant thrust. Our motivation stems from the fact that modern space missions are required to accurately control the position and orientation of spacecraft actuated by constant-thrust jet-thrusters. To comply with the performance limitations of modern thrusters, we design a feedback controller that does not induce high-frequency switching of the actuators. The proposed controller is hybrid and it asymptotically stabilizes an arbitrarily small compact neighborhood of the target position and orientation of the rigid body. The controller is characterized by a hierarchical structure comprising of two control layers. At the low level of the hierarchy, an attitude controller stabilizes the target orientation of the rigid body. At the high level, after the attitude controller has steered the rigid body sufficiently close to its desired orientation, a position controller stabilizes the desired position. The size of the neighborhood being stabilized by the controller can be adjusted via a proper selection of the controller parameters. This allows us to stabilize the rigid body to virtually any degree of accuracy. It is shown that the controller, even in the presence of measurement noise, does not induce high-frequency switching of the actuators. The key component in the design of the controller is a hybrid stabilizer for the origin of double-integrators affected by bounded external perturbations. Specifically, both the position and the attitude stabilizers consist of multiple copies of such a double-integrator controller. The proposed controller is applied to two realistic spacecraft control problems. First, we apply the position controller to the problem of stabilizing the relative position between two spacecraft flying in formation in the vicinity of the L2 libration point of the Sun-Earth system as a part of a large space telescope
The diagnostic role of thoracoscope in undiagnosed pleural effusion: Rigid versus flexible
Directory of Open Access Journals (Sweden)
Mostafa Mahmoud Abdel Mageid Shaheen
2014-07-01
Conclusions: Thoracoscopy using either fibreoptic bronchoscope or rigid thoracoscope is safe and well tolerated. Rigid thoracoscope has a higher diagnostic yield, easier handling, better orientation and is less expensive. Nevertheless, fibreoptic bronchoscope is an alternative technique if rigid thoracoscopy is not available.
Directory of Open Access Journals (Sweden)
Ali Esnaashari
2016-12-01
Full Text Available Special concentrically braced frames (SCBFs are commonly used to resist lateral loads in buildings. The bracing system sustains large deformations due to inelastic behavior in bracing members (buckling and yielding in tension. Generally, in the conventional modeling strategy, the effect of gusset plates in providing beam-column connections rigidity and hence, improving the post-buckling performance of these frames is not taken into account. This paper deals with the effect of gusset plate rigidity on the seismic behavior of SCBFs using Roeder’s proposed model in the literature. In this paper, four 3, 6, 9 and 12-story SCBFs were designed and modeled using two distinct methods: conventional method with hinged connections and Roeder’s method with semi-rigid connections. Then, the models behavior was investigated with both pushover analysis and nonlinear time-history analysis using OpenSees software. The results showed that lateral load capacity of the frames modeled with the Roeder’s proposed model are about 10% larger than the conventional method’s capacity. Also, it was found that the semi-rigid model leads to a less drift ratios and more overstrength factors.
International Nuclear Information System (INIS)
Jia, Zhenyong; Zhou, Qun; Li, Xiaowei; Fu, Yu; Ming, Hai; Zheng, Junwei
2015-01-01
Highlights: • Rigid porous framework of Li 4 Ti 5 O 12 microspheres can be fabricated by mutual molten growth of primary particles. • Well-confined nanosized tortuous channels are formed inside Li 4 Ti 5 O 12 microspheres. • Li 4 Ti 5 O 12 microspheres with rigid porous structures exhibit greatly enhanced electrochemical performance. - Abstract: Highly controllable porous architecture is desirable to tailor the physical and chemical properties of functional materials in advanced lithium ion batteries. Here, porous microspheres of spinel lithium titanate (Li 4 Ti 5 O 12 ), a promising alternative anode material for lithium ion batteries, are fabricated by mutual molten growth method in a controllable manner. The key role of the rigidity of the porous structure on the performance of the electrode materials in lithium ion batteries is demonstrated. Rigid framework of the materials is formed by second growth of the primary particles that fused together to generate an interconnected nanopore system inside the spheres, leading to better electrolyte diffusion and lower interparticle contact resistance, relative to the non-porous counterpart. The pristine Li 4 Ti 5 O 12 microspheres with uniform pore distribution and continuous framework exhibit high tap density, remarkable reversible capacity and rate capability, as well as excellent cycling stability. The present method is scalable and may provide a new approach to fabricate other candidate electrode materials for applications that require both high power and high volumetric energy density
Andrews, George E
1994-01-01
Although mathematics majors are usually conversant with number theory by the time they have completed a course in abstract algebra, other undergraduates, especially those in education and the liberal arts, often need a more basic introduction to the topic.In this book the author solves the problem of maintaining the interest of students at both levels by offering a combinatorial approach to elementary number theory. In studying number theory from such a perspective, mathematics majors are spared repetition and provided with new insights, while other students benefit from the consequent simpl
Schmidli, Hanspeter
2017-01-01
This book provides an overview of classical actuarial techniques, including material that is not readily accessible elsewhere such as the Ammeter risk model and the Markov-modulated risk model. Other topics covered include utility theory, credibility theory, claims reserving and ruin theory. The author treats both theoretical and practical aspects and also discusses links to Solvency II. Written by one of the leading experts in the field, these lecture notes serve as a valuable introduction to some of the most frequently used methods in non-life insurance. They will be of particular interest to graduate students, researchers and practitioners in insurance, finance and risk management.
DEFF Research Database (Denmark)
Smith, Shelley
This paper came about within the context of a 13-month research project, Focus Area 1 - Method and Theory, at the Center for Public Space Research at the Royal Academy of the Arts School of Architecture in Copenhagen, Denmark. This project has been funded by RealDania. The goals of the research...... project, Focus Area 1 - Method and Theory, which forms the framework for this working paper, are: * To provide a basis from which to discuss the concept of public space in a contemporary architectural and urban context - specifically relating to theory and method * To broaden the discussion of the concept...
Lubliner, Jacob
2008-01-01
The aim of Plasticity Theory is to provide a comprehensive introduction to the contemporary state of knowledge in basic plasticity theory and to its applications. It treats several areas not commonly found between the covers of a single book: the physics of plasticity, constitutive theory, dynamic plasticity, large-deformation plasticity, and numerical methods, in addition to a representative survey of problems treated by classical methods, such as elastic-plastic problems, plane plastic flow, and limit analysis; the problem discussed come from areas of interest to mechanical, structural, and
Gould, Ronald
2012-01-01
This introduction to graph theory focuses on well-established topics, covering primary techniques and including both algorithmic and theoretical problems. The algorithms are presented with a minimum of advanced data structures and programming details. This thoroughly corrected 1988 edition provides insights to computer scientists as well as advanced undergraduates and graduate students of topology, algebra, and matrix theory. Fundamental concepts and notation and elementary properties and operations are the first subjects, followed by examinations of paths and searching, trees, and networks. S
A major point in the relativistic gravitation theory
International Nuclear Information System (INIS)
Draminsky, P.
1976-01-01
In this article Draminsky gives his answer to those critics who, while noting his objections to Einstein's General Theory of Relativity, have been uncertain what Draminsky would put in its place. Draminsky's theory is based on the same foundation as Einstein's, that real space in a gravitational field is non-Euclidean. This space is contracted or dilated in relation to time in different ways from place to place. The tracks of free particles in such space are geodetic lines calculated from second-order differential equations, the form and solution of which is described. The single assumption required to provide a rigid and exact field equation is that the inertial mass of a particle in a local system of reference is the same as its gravitational mass measured and operative in the reference system: which is the 'identity principle' of Einstein formulated in the only entirely precise manner. (A.D.N.)
Directory of Open Access Journals (Sweden)
Maryam Montazeri
2013-01-01
Full Text Available This paper presents a control approach to the fuzzy-adaptive control scheme for rigid manipulators with unknown parameters. Lagrange’s method is employed for computing robot motion dynamics. Stability analysis guaranteed through Lyapunov’s theory using some suitable adaptive rules that make sure all signals in the closed-loop system are bounded and tracking error ones asymptotically reaches to zero. Compared with other controllers, there are some numerical simulations that verify effectiveness of the proposed method. Also, simulation results verify that the proposed controller can deal with uncertainties in the system.
Rigid microenvironments promote cardiac differentiation of mouse and human embryonic stem cells
Arshi, Armin; Nakashima, Yasuhiro; Nakano, Haruko; Eaimkhong, Sarayoot; Evseenko, Denis; Reed, Jason; Stieg, Adam Z.; Gimzewski, James K.; Nakano, Atsushi
2013-04-01
While adult heart muscle is the least regenerative of tissues, embryonic cardiomyocytes are proliferative, with embryonic stem (ES) cells providing an endless reservoir. In addition to secreted factors and cell-cell interactions, the extracellular microenvironment has been shown to play an important role in stem cell lineage specification, and understanding how scaffold elasticity influences cardiac differentiation is crucial to cardiac tissue engineering. Though previous studies have analyzed the role of matrix elasticity on the function of differentiated cardiomyocytes, whether it affects the induction of cardiomyocytes from pluripotent stem cells is poorly understood. Here, we examine the role of matrix rigidity on cardiac differentiation using mouse and human ES cells. Culture on polydimethylsiloxane (PDMS) substrates of varied monomer-to-crosslinker ratios revealed that rigid extracellular matrices promote a higher yield of de novo cardiomyocytes from undifferentiated ES cells. Using a genetically modified ES system that allows us to purify differentiated cardiomyocytes by drug selection, we demonstrate that rigid environments induce higher cardiac troponin T expression, beating rate of foci, and expression ratio of adult α- to fetal β- myosin heavy chain in a purified cardiac population. M-mode and mechanical interferometry image analyses demonstrate that these ES-derived cardiomyocytes display functional maturity and synchronization of beating when co-cultured with neonatal cardiomyocytes harvested from a developing embryo. Together, these data identify matrix stiffness as an independent factor that instructs not only the maturation of already differentiated cardiomyocytes but also the induction and proliferation of cardiomyocytes from undifferentiated progenitors. Manipulation of the stiffness will help direct the production of functional cardiomyocytes en masse from stem cells for regenerative medicine purposes.
A framework for automatic creation of gold-standard rigid 3D-2D registration datasets.
Madan, Hennadii; Pernuš, Franjo; Likar, Boštjan; Špiclin, Žiga
2017-02-01
Advanced image-guided medical procedures incorporate 2D intra-interventional information into pre-interventional 3D image and plan of the procedure through 3D/2D image registration (32R). To enter clinical use, and even for publication purposes, novel and existing 32R methods have to be rigorously validated. The performance of a 32R method can be estimated by comparing it to an accurate reference or gold standard method (usually based on fiducial markers) on the same set of images (gold standard dataset). Objective validation and comparison of methods are possible only if evaluation methodology is standardized, and the gold standard dataset is made publicly available. Currently, very few such datasets exist and only one contains images of multiple patients acquired during a procedure. To encourage the creation of gold standard 32R datasets, we propose an automatic framework. The framework is based on rigid registration of fiducial markers. The main novelty is spatial grouping of fiducial markers on the carrier device, which enables automatic marker localization and identification across the 3D and 2D images. The proposed framework was demonstrated on clinical angiograms of 20 patients. Rigid 32R computed by the framework was more accurate than that obtained manually, with the respective target registration error below 0.027 mm compared to 0.040 mm. The framework is applicable for gold standard setup on any rigid anatomy, provided that the acquired images contain spatially grouped fiducial markers. The gold standard datasets and software will be made publicly available.
Arbitrary scattering of an acoustical Bessel beam by a rigid spheroid with large aspect-ratio
Gong, Zhixiong; Li, Wei; Mitri, Farid G.; Chai, Yingbin; Zhao, Yao
2016-11-01
In this paper, the T-matrix (null-field) method is applied to investigate the acoustic scattering by a large-aspect-ratio rigid spheroid immersed in a non-viscous fluid under the illumination of an unbounded zeroth-order Bessel beam with arbitrary orientation. Based on the proposed method, a MATLAB software package is constructed accordingly, and then verified and validated to compute the acoustic scattering by a rigid oblate or prolate spheroid in the Bessel beam. Several numerical examples are carried out to investigate the novel phenomenon of acoustic scattering by spheroids in Bessel beams with arbitrary incidence, with particular emphasis on the aspect ratio (i.e. the ratio of the polar radius over the equatorial radius of the spheroid), the half-cone angle of Bessel beam, the dimensionless frequency, as well as the angle of incidence. The quasi-periodic oscillations are observed in the plots of the far-field backscattering form function modulus versus the dimensionless frequency, owing to the interference between the specular reflection and the Franz wave circumnavigating the spheroid in the surrounding fluid. Furthermore, the 3D far-field scattering directivity patterns at end-on incidence and 2D polar plots at arbitrary angles of incidence are exhibited, which could provide new insights into the physical mechanisms of Bessel beam scattering by flat or elongated spheroid. This research work may provide an impetus for the application of acoustic Bessel beam in engineering practices.
Rigid missiles impact on reinforced concrete structures: analysis by discrete element method
International Nuclear Information System (INIS)
Shiu, W.J.
2008-10-01
The constructions likely to be subjected to some extreme loadings like reactor containment buildings have to be dimensioned accordingly. As a part of study of concrete structures, this thesis focuses on numerical modelling of rigid missile impacts against a rigid reinforced concrete slab. Based on some experiment tests data, an elasto-plastic-damaged constitutive law has been implanted into a discrete element numerical code. To calibrate certain parameters of the numerical model, some quasi static tests have been first simulated. Once the model calibration was done, some missile impact simulation tests have then been carried out. The numerical results are well agree with these provided by French Atomic Energy Agency (Cea) and the French Electrical power Company (EDF) in terms of the trajectory of the missile. We were able to show the need of a constitutive law taking into account the compaction behaviour of the concrete when the predictions of penetration and perforation of a thick slab was demanded. Finally, a parametric study confirmed that the numerical model can be used the way predictive as well as the empirical prediction law, while the first can provide additional significant mechanical description. (author)
Ghezel-Ahmadi, Verena; Ghezel-Ahmadi, David; Mangen, Jacques; Bolukbas, Servet; Welker, Andreas; Kuerschner, Veit Christian; Fischer, Andreas; Schirren, Joachim; Beck, Grietje
2015-09-01
Despite its serious side effects, succinylcholine is commonly used for neuromuscular relaxation in short procedures, such as rigid bronchoscopy and tracheobronchial interventions. The application of low-dose rocuronium reversed by low-dose sugammadex might be a modern alternative. The aim of this study was to compare patient satisfaction, incidence of postoperative myalgia (POM) as well as intubating conditions of these two muscle relaxants for rigid bronchoscopy. A single-center, prospective-randomized, blinded study of 95 patients, scheduled for rigid bronchoscopy and tracheobronchial intervention was conducted. The patients were anesthetized with propofol, remifentanil and either low-dose succinylcholine (S) (0.5 mg/kg) or low-dose rocuronium (0.25 mg/kg) with sugammadex (RS) (0.5 mg/kg). All patients were evaluated on the first and second postinterventional day for their satisfaction with the treatment (rigid bronchoscopy) using a Numeric Analog Rating Scale (NAS 0-10) and the presence and severity of POM (NAS 1-4). Intubating conditions were assessed as excellent, good, or poor on the basis of position of vocal cords and reaction to insertion of the rigid bronchoscope. Patients in the S group were less satisfied with the treatment than patients in RS group (72.7 vs. 93.7%, p = 0.007). The incidence of POM on the first day after intervention was significantly higher in the S group then in the RS group (56.9% vs. 4.3%, p rocuronium in 75% of patients. The anesthetic drug costs were significantly higher in the RS group then in the S group (p rocuronium provided better patient satisfaction and less POM. But with the use of low-dose succinylcholine, the intubating conditions are more comfortable, and it is less expensive than rocuronium/sugammadex. Georg Thieme Verlag KG Stuttgart · New York.
Cohomological rigidity of manifolds defined by 3-dimensional polytopes
Buchstaber, V. M.; Erokhovets, N. Yu.; Masuda, M.; Panov, T. E.; Park, S.
2017-04-01
A family of closed manifolds is said to be cohomologically rigid if a cohomology ring isomorphism implies a diffeomorphism for any two manifolds in the family. Cohomological rigidity is established here for large families of 3-dimensional and 6-dimensional manifolds defined by 3-dimensional polytopes. The class \\mathscr{P} of 3-dimensional combinatorial simple polytopes P different from tetrahedra and without facets forming 3- and 4-belts is studied. This class includes mathematical fullerenes, that is, simple 3- polytopes with only 5-gonal and 6-gonal facets. By a theorem of Pogorelov, any polytope in \\mathscr{P} admits in Lobachevsky 3-space a right-angled realisation which is unique up to isometry. Our families of smooth manifolds are associated with polytopes in the class \\mathscr{P}. The first family consists of 3-dimensional small covers of polytopes in \\mathscr{P}, or equivalently, hyperbolic 3-manifolds of Löbell type. The second family consists of 6-dimensional quasitoric manifolds over polytopes in \\mathscr{P}. Our main result is that both families are cohomologically rigid, that is, two manifolds M and M' from either family are diffeomorphic if and only if their cohomology rings are isomorphic. It is also proved that if M and M' are diffeomorphic, then their corresponding polytopes P and P' are combinatorially equivalent. These results are intertwined with classical subjects in geometry and topology such as the combinatorics of 3-polytopes, the Four Colour Theorem, aspherical manifolds, a diffeomorphism classification of 6-manifolds, and invariance of Pontryagin classes. The proofs use techniques of toric topology. Bibliography: 69 titles.
Vertical dimensional stability and rigidity of occlusal registration materials.
Walker, Mary P; Wu, Edis; Heckman, M Elizabeth; Alderman, Nicholas
2009-01-01
Dimensionally accurate occlusal registration records are essential for restorative dentistry; moreover, since records are not used immediately or may be used more than once, the registration material should exhibit accuracy over time (a concept known as dimensional stability). It has been speculated that materials with increased hardness or rigidity should produce more accurate registration records due to an increased resistance to distortion. This study compared the rigidity and associated dimensional accuracy of a recently marketed bisacrylic occlusal registration material and a vinyl polysiloxane (VPS). Maxillary and mandibular typodont arches were mounted on a plasterless articulator from which teeth No. 3, 13, and 15 had been removed to simulate edentulous spaces. After preparing teeth No. 2, 4, 12, and 14 as bridge abutments, the remaining teeth were equilibrated selectively to produce even anterior contact. Four digital photographs were taken to make vertical interarch measurements at four locations (teeth No. 3, 7, 10, and 14). Following initial photos (controls), 10 interocclusal records were made using each registration material, with material placed only in the segments in which teeth were prepared. The records were used for mounting the maxillary arch against the mandibular arch after 48, 72, and 120 hours. There were significant effects on vertical dimensional change related to arch location, material, and mounting time. Both materials demonstrated significantly larger posterior vertical openings than anterior vertical openings, while the bisacrylate produced a larger posterior opening than VPS at 48 and 72 hours and a larger anterior opening at all mounting times. There also was a significant difference in hardness/rigidity due to material and measurement time; at all measurement times, bisacrylate exhibited a significantly higher hardness number.
Friction effects on lateral loading behavior of rigid piles
DEFF Research Database (Denmark)
Zania, Varvara; Hededal, Ole
2012-01-01
taking into account the shear frictional resistance along the pile. For this purpose efficient three dimensional finite element models of different diameter have been developed. The increase of the side friction and of the diameter of the pile is shown to alter the failure pattern and increase...... the lateral capacity of the pile. The obtained p - y curves demonstrate the importance of the aforementioned parameters in the design of rigid piles, as the reduction of friction along the interface reduces not only the ultimate load but also the stiffness of the soil-pile response. Read More: http...
Cosmic ray fluctuations at rigidities 4 to 180 GV
International Nuclear Information System (INIS)
Benko, G.; Erdoes, G.; Stehlik, M.; Katz, M.E.; Nosov, S.F.
1986-07-01
The power spectral density of cosmic ray fluctuations observed at both underground and ground level during the years 1976-1980 was calculated. The spectral index is independent of the phase of solar cycle in the frequency range of 5x10 -7 - 5x10 -5 Hz and its value is equal to 2. The level of fluctuations shows a weak dependence on the rigidity (R) of the particles P∼R -2/3 . The obtained experimental results are in agreement with the theoretical predictions. (author)
Rigidity of minimal submanifolds with flat normal bundle
Indian Academy of Sciences (India)
Rigidity of minimal submanifolds with flat normal bundle. 461. = a. ∫. M u2(1+q)+ 2 a f 2 − 2. ∫. M u2q+1f 〈∇f, ∇u〉. − (2q + 1). ∫. M u2qf 2|∇u|2, which gives a .... that depends on n, ϵ and q. We now try to transform (2.15) the right hand side only involved u in the power two. For that, we use Young's inequality: ab ≤ βsas.
Tilting mode in rigidly rotating field-reversed configurations
International Nuclear Information System (INIS)
Clemente, R.A.; Milovich, J.L.
1983-01-01
The tilting-mode stability of field-reversed configurations is analyzed taking into account plasma rotational effects that had not been included in previous theoretical treatments. It is shown that for a rigidly rotating plasma in stationary equilibrium, stability can be attained if the plasma rotational energy is of the same order as the thermal energy. Since presently available values of the rotational velocities are quite lower than required by the stabilization mechanism considered here, the contribution of this effect to the overall stability of the mode does not appear to be significant
Rigid supersymmetry from conformal supergravity in five dimensions
International Nuclear Information System (INIS)
Pini, Alessandro; Rodriguez-Gomez, Diego; Schmude, Johannes
2015-01-01
We study the rigid limit of 5d conformal supergravity with minimal supersymmetry on Riemannian manifolds. The necessary and sufficient condition for the existence of a solution is the existence of a conformal Killing vector. Whenever a certain SU(2) curvature becomes abelian the backgrounds define a transversally holomorphic foliation. Subsequently we turn to the question under which circumstances these backgrounds admit a kinetic Yang-Mills term in the action of a vector multiplet. Here we find that the conformal Killing vector has to be Killing. We supplement the discussion with various appendices.
Numerical rigid plastic modelling of shear capacity of keyed joints
DEFF Research Database (Denmark)
Herfelt, Morten Andersen; Poulsen, Peter Noe; Hoang, Linh Cao
2015-01-01
Keyed shear joints are currently designed using simple and conservative design formulas, yet these formulas do not take the local mechanisms in the concrete core of the joint into account. To investigate this phenomenon a rigid, perfectly plastic finite element model of keyed joints is used....... The model is formulated for second-order conic optimisation as a lower bound problem, which yields a statically admissible stress field that satisfies the yield condition in every point. The dual solution to the problem can be interpreted as the collapse mode and will be used to analyse the properties...
Nonlinear complex dynamics and Keynesian rigidity: A short introduction
Jovero, Edgardo
2005-09-01
The topic of this paper is to show that the greater acceptance and intense use of complex nonlinear dynamics in macroeconomics makes sense only within the neoKeynesian tradition. An example is presented regarding the behavior of an open-economy two-sector growth model endowed with Keynesian rigidity. The Keynesian view that structural instability globally exists in the aggregate economy is put forward, and therefore the need arises for policy to alleviate this instability in the form of dampened fluctuations is presented as an alternative view for macroeconomic theorizing.
Euler-Poincare Reduction of Externall Forced Rigid Body Motion
DEFF Research Database (Denmark)
Wisniewski, Rafal; Kulczycki, P.
2004-01-01
If a mechanical system experiences symmetry, the Lagrangian becomes invariant under a certain group action. This property leads to substantial simplification of the description of movement. The standpoint in this article is a mechanical system affected by an external force of a control action....... Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincaré reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modelling, estimation and control of mechanical systems......-known Euler-Poincaré reduction to a rigid body motion with forcing....
Euler-Poincare Reduction of a Rigid Body Motion
DEFF Research Database (Denmark)
Wisniewski, Rafal; Kulczycki, P.
2005-01-01
|If a mechanical system experiences symmetry, the Lagrangian becomes invariant under a certain group action. This property leads to substantial simplification of the description of movement. The standpoint in this article is a mechanical system afected by an external force of a control action....... Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincare reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modeling, estimation and control of mechanical systems......-known Euler-Poincare reduction to a rigid body motion with forcing....
Euler-Poincaré Reduction of a Rigid Body Motion
DEFF Research Database (Denmark)
Wisniewski, Rafal; Kulczycki, P.
2004-01-01
If a mechanical system experiences symmetry, the Lagrangian becomes invariant under a certain group action. This property leads to substantial simplification of the description of movement. The standpoint in this article is a mechanical system affected by an external force of a control action....... Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincaré reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modelling, estimation and control of mechanical systems......-known Euler-Poincaré reduction to a rigid body motion with forcing....
DEFF Research Database (Denmark)
Andersen, Jack
2015-01-01
Purpose To provide a small overview of genre theory and its associated concepts and to show how genre theory has had its antecedents in certain parts of the social sciences and not in the humanities. Findings The chapter argues that the explanatory force of genre theory may be explained with its...... emphasis on everyday genres, de facto genres. Originality/value By providing an overview of genre theory, the chapter demonstrates the wealth and richness of forms of explanations in genre theory....
Nel, Louis
2016-01-01
This book presents a detailed, self-contained theory of continuous mappings. It is mainly addressed to students who have already studied these mappings in the setting of metric spaces, as well as multidimensional differential calculus. The needed background facts about sets, metric spaces and linear algebra are developed in detail, so as to provide a seamless transition between students' previous studies and new material. In view of its many novel features, this book will be of interest also to mature readers who have studied continuous mappings from the subject's classical texts and wish to become acquainted with a new approach. The theory of continuous mappings serves as infrastructure for more specialized mathematical theories like differential equations, integral equations, operator theory, dynamical systems, global analysis, topological groups, topological rings and many more. In light of the centrality of the topic, a book of this kind fits a variety of applications, especially those that contribute to ...
De Chant, L J
1999-10-01
An approximate analytical model for the pulsatile flow of an ideal Bingham plastic fluid in both a rigid and a periodically displaced tube has been developed using regular perturbation methods. Relationships are derived for the velocity field and dimensionless flow rate. The solution compares adequately with available experimentally measured oscillatory non-Newtonian fluid flow data. These solutions provide useful analytical models supporting experimental and computation studies of arterial blood flow.
Dynamic response and stability of semi-rigid frames
Abu-Yasein, Omar Ali
This dissertation presents a method to determine the load capacity as well as end member forces and deformations of frames with partial rigid joint connections by using the direct stiffness method. The connections are modeled as rotational springs attached at the ends of framed members. The lumped mass method, which is an approximate method, and the distributed mass method, which is an exact method, are also presented to compute the natural frequency of frames. The effects of the axial forces and the flexibility of joint connections are both included. Furthermore, the time-dependent response of semi-rigid frames subjected to periodic axial forces is formulated. The harmonic function is approximated by dividing the periodic function into n intervals and the periodic axial forces are evaluated at each time interval as constant forces using 'piecewise approximation'. The regions of instability of frames with different joint stiffness were determined using the characteristic equation method. The time-dependent part of the differential equation for free vibration of a framed member subjected to a harmonic force can be written in the form of the Mathieu-Hill equation where all characteristics of the Mathieu-Hill equation solutions can be used to determine the boundaries of instability regions.
A Soft Gripper with Rigidity Tunable Elastomer Strips as Ligaments.
Nasab, Amir Mohammadi; Sabzehzar, Amin; Tatari, Milad; Majidi, Carmel; Shan, Wanliang
2017-12-01
Like their natural counterparts, soft bioinspired robots capable of actively tuning their mechanical rigidity can rapidly transition between a broad range of motor tasks-from lifting heavy loads to dexterous manipulation of delicate objects. Reversible rigidity tuning also enables soft robot actuators to reroute their internal loading and alter their mode of deformation in response to intrinsic activation. In this study, we demonstrate this principle with a three-fingered pneumatic gripper that contains "programmable" ligaments that change stiffness when activated with electrical current. The ligaments are composed of a conductive, thermoplastic elastomer composite that reversibly softens under resistive heating. Depending on which ligaments are activated, the gripper will bend inward to pick up an object, bend laterally to twist it, and bend outward to release it. All of the gripper motions are generated with a single pneumatic source of pressure. An activation-deactivation cycle can be completed within 15 s. The ability to incorporate electrically programmable ligaments in a pneumatic or hydraulic actuator has the potential to enhance versatility and reduce dependency on tubing and valves.
Jet Ventilation during Rigid Bronchoscopy in Adults: A Focused Review
Directory of Open Access Journals (Sweden)
Laurie Putz
2016-01-01
Full Text Available The indications for rigid bronchoscopy for interventional pulmonology have increased and include stent placements and transbronchial cryobiopsy procedures. The shared airway between anesthesiologist and pulmonologist and the open airway system, requiring specific ventilation techniques such as jet ventilation, need a good understanding of the procedure to reduce potentially harmful complications. Appropriate adjustment of the ventilator settings including pause pressure and peak inspiratory pressure reduces the risk of barotrauma. High frequency jet ventilation allows adequate oxygenation and carbon dioxide removal even in cases of tracheal stenosis up to frequencies of around 150 min−1; however, in an in vivo animal model, high frequency jet ventilation along with normal frequency jet ventilation (superimposed high frequency jet ventilation has been shown to improve oxygenation by increasing lung volume and carbon dioxide removal by increasing tidal volume across a large spectrum of frequencies without increasing barotrauma. General anesthesia with a continuous, intravenous, short-acting agent is safe and effective during rigid bronchoscopy procedures.
Non-rigid registration of tomographic images with Fourier transforms
International Nuclear Information System (INIS)
Osorio, Ar; Isoardi, Ra; Mato, G
2007-01-01
Spatial image registration of deformable body parts such as thorax and abdomen has important medical applications, but at the same time, it represents an important computational challenge. In this work we propose an automatic algorithm to perform non-rigid registration of tomographic images using a non-rigid model based on Fourier transforms. As a measure of similarity, we use the correlation coefficient, finding that the optimal order of the transformation is n = 3 (36 parameters). We apply this method to a digital phantom and to 7 pairs of patient images corresponding to clinical CT scans. The preliminary results indicate a fairly good agreement according to medical experts, with an average registration error of 2 mm for the case of clinical images. For 2D images (dimensions 512x512), the average running time for the algorithm is 15 seconds using a standard personal computer. Summarizing, we find that intra-modality registration of the abdomen can be achieved with acceptable accuracy for slight deformations and can be extended to 3D with a reasonable execution time
Modyfication of the Rigid Polyurethane-Polyisocyanurate Foams
Directory of Open Access Journals (Sweden)
Bogusław Czupryński
2014-01-01
Full Text Available The effect of polyethylene glycol 1500 on physicomechanical properties of rigid polyurethane-polyisocyanurate (PUR-PIR foams has been studied. It was found that application of polyethylene glycol 1500 for synthesis of foams in amount from 0% to 20% w/w had an effect on reduction of brittleness and softening point, while the greater the increase in compressive strength the higher its content in foam composition was. Wastes from production of these foams were ground and subjected to glycolysis in diethylene glycol with the addition of ethanolamine and zinc stearate. Liquid brown products were obtained. Properties of the resulting products were defined in order to determine their suitability for synthesis of new foams. It was found that glycolysate 6 was the most suitable for reuse and its application in different amounts allowed us to prepare 4 new foams (nos. 25, 26, 27, and 28. Properties of foams prepared in this manner were determined and, on their basis, the suitability of glycolysates for production of rigid PUR-PIR foams was evaluated.
Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation
Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.
2012-01-01
Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.
Finite-difference analysis of shells impacting rigid barriers
International Nuclear Information System (INIS)
Pirotin, S.D.; Witmer, E.A.
1977-01-01
Nuclear power plants must be protected from the adverse effects of missile impacts. A significant category of missile impact involves deformable structures (pressure vessel components, whipping pipes) striking relatively rigid targets (concrete walls, bumpers) which act as protective devices. The response and interaction of these structures is needed to assess the adequacy of these barriers for protecting vital safety related equipment. The present investigation represents an initial attempt to develop an efficient numerical procedure for predicting the deformations and impact force time-histories of shells which impact upon a rigid target. The general large-deflection equations of motion of the shell are expressed in finite-difference form in space and integrated in time through application of the central-difference temporal operator. The effect of material nonlinearities is treated by a mechanical sublayer material model which handles the strain-hardening, Bauschinger, and strain-rate effects. The general adequacy of this shell treatment has been validated by comparing predictions with the results of various experiments in which structures have been subjected to well-defined transient forcing functions (typically high-explosive impulse loading). The 'new' ingredient addressed in the present study involves an accounting for impact interaction and response of both the target structure and the attacking body. (Auth.)
Origami-Inspired Folding of Thick, Rigid Panels
Trease, Brian P.; Thomson, Mark W.; Sigel, Deborah A.; Walkemeyer, Phillip E.; Zirbel, Shannon; Howell, Larry; Lang, Robert
2014-01-01
To achieve power of 250 kW or greater, a large compression ratio of stowed-to-deployed area is needed. Origami folding patterns were used to inspire the folding of a solar array to achieve synchronous deployment; however, origami models are generally created for near-zero-thickness material. Panel thickness is one of the main challenges of origami-inspired design. Three origami-inspired folding techniques (flasher, square twist, and map fold) were created with rigid panels and hinges. Hinge components are added to the model to enable folding of thick, rigid materials. Origami models are created assuming zero (or near zero) thickness. When a material with finite thickness is used, the panels are required to bend around an increasingly thick fold as they move away from the center of the model. The two approaches for dealing with material thickness are to use membrane hinges to connect the panels, or to add panel hinges, or hinges of the same thickness, at an appropriate width to enable folding.
Awake craniotomy using electromagnetic navigation technology without rigid pin fixation.
Morsy, Ahmed A; Ng, Wai Hoe
2015-11-01
We report our institutional experience using an electromagnetic navigation system, without rigid head fixation, for awake craniotomy patients. The StealthStation® S7 AxiEM™ navigation system (Medtronic, Inc.) was used for this technique. Detailed preoperative clinical and neuropsychological evaluations, patient education and contrast-enhanced MRI (thickness 1.5mm) were performed for each patient. The AxiEM Mobile Emitter was typically placed in a holder, which was mounted to the operating room table, and a non-invasive patient tracker was used as the patient reference device. A monitored conscious sedation technique was used in all awake craniotomy patients, and the AxiEM Navigation Pointer was used for navigation during the procedure. This offers the same accuracy as optical navigation, but without head pin fixation or interference with intraoperative neurophysiological techniques and surgical instruments. The application of the electromagnetic neuronavigation technology without rigid head fixation during an awake craniotomy is accurate, and offers superior patient comfort. It is recommended as an effective adjunctive technique for the conduct of awake surgery. Copyright © 2015 Elsevier Ltd. All rights reserved.
Dynamics of parallel robots from rigid bodies to flexible elements
Briot, Sébastien
2015-01-01
This book starts with a short recapitulation on basic concepts, common to any types of robots (serial, tree structure, parallel, etc.), that are also necessary for computation of the dynamic models of parallel robots. Then, as dynamics requires the use of geometry and kinematics, the general equations of geometric and kinematic models of parallel robots are given. After, it is explained that parallel robot dynamic models can be obtained by decomposing the real robot into two virtual systems: a tree-structure robot (equivalent to the robot legs for which all joints would be actuated) plus a free body corresponding to the platform. Thus, the dynamics of rigid tree-structure robots is analyzed and algorithms to obtain their dynamic models in the most compact form are given. The dynamic model of the real rigid parallel robot is obtained by closing the loops through the use of the Lagrange multipliers. The problem of the dynamic model degeneracy near singularities is treated and optimal trajectory planning for cro...
Iterative CT reconstruction with correction for known rigid motion
Energy Technology Data Exchange (ETDEWEB)
Nuyts, Johan [Katholieke Univ. Leuven (Belgium). Dept. of Nuclear Medicine; Kim, Jung-Ha; Fulton, Roger [Sydney Univ., NSW (Australia). School of Physics; Westmead Hospital, Sydney (Australia). Medical Physics
2011-07-01
In PET/CT brain imaging, correction for motion may be needed, in particular for children and psychiatric patients. Motion is more likely to occur in the lengthy PET measurement, but also during the short CT acquisition patient motion is possible. Rigid motion of the head can be measured independently from the PET/CT system with optical devices. In this paper, we propose a method and some preliminary simulation results for iterative CT reconstruction with correction for known rigid motion. We implemented an iterative algorithm for fully 3D reconstruction from helical CT scans. The motion of the head is incorporated in the system matrix as a view-dependent motion of the CT-system. The first simulation results indicate that some motion patterns may produce loss of essential data. This loss precludes exact reconstruction and results in artifacts in the reconstruction, even when motion is taken into account. However, by reducing the pitch during acquisition, the same motion pattern no longer caused artifacts in the motion corrected image. (orig.)
A method for measuring the inertia properties of rigid bodies
Gobbi, M.; Mastinu, G.; Previati, G.
2011-01-01
A method for the measurement of the inertia properties of rigid bodies is presented. Given a rigid body and its mass, the method allows to measure (identify) the centre of gravity location and the inertia tensor during a single test. The proposed technique is based on the analysis of the free motion of a multi-cable pendulum to which the body under consideration is connected. The motion of the pendulum and the forces acting on the system are recorded and the inertia properties are identified by means of a proper mathematical procedure based on a least square estimation. After the body is positioned on the test rig, the full identification procedure takes less than 10 min. The natural frequencies of the pendulum and the accelerations involved are quite low, making this method suitable for many practical applications. In this paper, the proposed method is described and two test rigs are presented: the first is developed for bodies up to 3500 kg and the second for bodies up to 400 kg. A validation of the measurement method is performed with satisfactory results. The test rig holds a third part quality certificate according to an ISO 9001 standard and could be scaled up to measure the inertia properties of huge bodies, such as trucks, airplanes or even ships.
Measurement of Spindle Rigidity by using a Magnet Loader
Yamazaki, Taku; Matsubara, Atsushi; Fujita, Tomoya; Muraki, Toshiyuki; Asano, Kohei; Kawashima, Kazuyuki
The static rigidity of a rotating spindle in the radial direction is investigated in this research. A magnetic loading device (magnet loader) has been developed for the measurement. The magnet loader, which has coils and iron cores, generates the electromagnetic force and attracts a dummy tool attached to the spindle. However, the eddy current is generated in the dummy tool with the spindle rotation and reduces the attractive force at high spindle speed. In order to understand the magnetic flux and eddy current in the dummy tool, the electromagnetic field analysis by FEM was carried out. Grooves on the attraction surface of the dummy tool were designed to cut the eddy current flow. The dimension of the groove were decided based on the FEM analysis, and the designed tool were manufactured and tested. The test result shows that the designed tool successfully reduces the eddy current and recovers the attractive force. By using the magnet loader and the grooved tool, the spindle rigidity can be measured when the spindle rotates with a speed up to 10,000 min-1.
Synthesis of rigid polyurethane foams from phosphorylated biopolyols.
de Haro, Juan Carlos; López-Pedrajas, Daniel; Pérez, Ángel; Rodríguez, Juan Francisco; Carmona, Manuel
2017-08-18
Renewable resources are playing a key role on the synthesis of biodegradable polyols. Moreover, the incorporation of covalently linked additives is increasing in importance in the polyurethane (PU) market. In this work, previously epoxidized grape seed oil and methyl oleate were transformed into phosphorylated biopolyols through an acid-catalyzed ring-opening hydrolysis in the presence of H 3 PO 4 . The formation of phosphate polyesters was confirmed by FT-IR and 31 P-NMR. However, the synthesis of a high-quality PU rigid foam was not possible using exclusively these polyols attending to their low hydroxyl value. In that way, different rigid PU foams were prepared from the phosphorylated biopolyols and the commercial polyol Alcupol R4520. It was observed that phosphorylated biopolyols can be incorporated up to a 57 wt.% in the PU synthesis without significant structural changes with respect to the commercial foam. Finally, thermogravimetric and EDAX analyses revealed an improvement of thermal stability by the formation of a protective phosphorocarbonaceous char layer.
Rigidity of quantum steering and one-sided device-independent verifiable quantum computation
International Nuclear Information System (INIS)
Gheorghiu, Alexandru; Wallden, Petros; Kashefi, Elham
2017-01-01
The relationship between correlations and entanglement has played a major role in understanding quantum theory since the work of Einstein et al (1935 Phys. Rev. 47 777–80). Tsirelson proved that Bell states, shared among two parties, when measured suitably, achieve the maximum non-local correlations allowed by quantum mechanics (Cirel’son 1980 Lett. Math. Phys. 4 93–100). Conversely, Reichardt et al showed that observing the maximal correlation value over a sequence of repeated measurements, implies that the underlying quantum state is close to a tensor product of maximally entangled states and, moreover, that it is measured according to an ideal strategy (Reichardt et al 2013 Nature 496 456–60). However, this strong rigidity result comes at a high price, requiring a large number of entangled pairs to be tested. In this paper, we present a significant improvement in terms of the overhead by instead considering quantum steering where the device of the one side is trusted. We first demonstrate a robust one-sided device-independent version of self-testing, which characterises the shared state and measurement operators of two parties up to a certain bound. We show that this bound is optimal up to constant factors and we generalise the results for the most general attacks. This leads us to a rigidity theorem for maximal steering correlations. As a key application we give a one-sided device-independent protocol for verifiable delegated quantum computation, and compare it to other existing protocols, to highlight the cost of trust assumptions. Finally, we show that under reasonable assumptions, the states shared in order to run a certain type of verification protocol must be unitarily equivalent to perfect Bell states. (paper)
The First Quantum Theory of Molecules
Indian Academy of Sciences (India)
IAS Admin
rotational energies of diatomic molecules. That theory was ... resent the intensity of light emitted by a black body as a function of ... by the vibrational motion of its parts”. Bjerrum was .... −1/4; despite the fact that no molecule is a rigid rotor,.
Rigid two-axis MEMS force plate for measuring cellular traction force
International Nuclear Information System (INIS)
Takahashi, Hidetoshi; Jung, Uijin G; Shimoyama, Isao; Kan, Tetsuo; Tsukagoshi, Takuya; Matsumoto, Kiyoshi
2016-01-01
Cellular traction force is one of the important factors for understanding cell behaviors, such as spreading, migration and differentiation. Cells are known to change their behavior according to the mechanical stiffness of the environment. However, the measurement of cell traction forces on a rigid environment has remained difficult. This paper reports a micro-electromechanical systems (MEMS) force plate that provides a cellular traction force measurement on a rigid substrate. Both the high force sensitivity and high stiffness of the substrate were obtained using piezoresistive sensing elements. The proposed force plate consists of a 70 µ m × 15 µ m × 5 µ m base as the substrate for cultivating a bovine aortic smooth muscle cell, and the supporting beams with piezoresistors on the sidewall and the surface were used to measure the forces in both the horizontal and vertical directions. The spring constant and force resolution of the fabricated force plate in the horizontal direction were 0.2 N m −1 and less than 0.05 µ N, respectively. The cell traction force was measured, and the traction force increased by approximately 1 µ N over 30 min. These results demonstrate that the proposed force plate is applicable as an effective traction force measurement. (paper)
Structural rigidity in the capsid assembly of cowpea chlorotic mottle virus
International Nuclear Information System (INIS)
Hespenheide, B M; Jacobs, D J; Thorpe, M F
2004-01-01
The cowpea chlorotic mottle virus (CCMV) has a protein cage, or capsid, which encloses its genetic material. The structure of the capsid consists of 180 copies of a single protein that self-assemble inside a cell to form a complete capsid with icosahedral symmetry. The icosahedral surface can be naturally divided into pentagonal and hexagonal faces, and the formation of either of these faces has been proposed to be the first step in the capsid assembly process. We have used the software FIRST to analyse the rigidity of pentameric and hexameric substructures of the complete capsid to explore the viability of certain capsid assembly pathways. FIRST uses the 3D pebble game to determine structural rigidity, and a brief description of this algorithm, as applied to body-bar networks, is given here. We find that the pentameric substructure, which corresponds to a pentagonal face on the icosahedral surface, provides the best structural properties for nucleating the capsid assembly process, consistent with experimental observations
Structural rigidity in the capsid assembly of cowpea chlorotic mottle virus
Hespenheide, B. M.; Jacobs, D. J.; Thorpe, M. F.
2004-11-01
The cowpea chlorotic mottle virus (CCMV) has a protein cage, or capsid, which encloses its genetic material. The structure of the capsid consists of 180 copies of a single protein that self-assemble inside a cell to form a complete capsid with icosahedral symmetry. The icosahedral surface can be naturally divided into pentagonal and hexagonal faces, and the formation of either of these faces has been proposed to be the first step in the capsid assembly process. We have used the software FIRST to analyse the rigidity of pentameric and hexameric substructures of the complete capsid to explore the viability of certain capsid assembly pathways. FIRST uses the 3D pebble game to determine structural rigidity, and a brief description of this algorithm, as applied to body-bar networks, is given here. We find that the pentameric substructure, which corresponds to a pentagonal face on the icosahedral surface, provides the best structural properties for nucleating the capsid assembly process, consistent with experimental observations.
Numerical analysis of MHD Casson Navier's slip nanofluid flow yield by rigid rotating disk
Rehman, Khalil Ur; Malik, M. Y.; Zahri, Mostafa; Tahir, M.
2018-03-01
An exertion is perform to report analysis on Casson liquid equipped above the rigid disk for z bar > 0 as a semi-infinite region. The flow of Casson liquid is achieve through rotation of rigid disk with constant angular frequency Ω bar . Magnetic interaction is consider by applying uniform magnetic field normal to the axial direction. The nanosized particles are suspended in the Casson liquid and rotation of disk is manifested with Navier's slip condition, heat generation/absorption and chemical reaction effects. The obtain flow narrating differential equations subject to MHD Casson nanofluid are transformed into ordinary differential system. For this purpose the Von Karman way of scheme is executed. To achieve accurate trends a computational algorithm is develop rather than to go on with usual build-in scheme. The effects logs of involved parameters, namely magnetic field parameter, Casson fluid parameter, slip parameter, thermophoresis and Brownian motion parameters on radial, tangential velocities, temperature, nanoparticles concentration, Nusselt and Sherwood numbers are provided by means of graphical and tabular structures. It is observed that both tangential and radial velocities are decreasing function of Casson fluid parameter.
Pazderková, Markéta; Profant, Václav; Hodačová, Jana; Sebestík, Jaroslav; Pazderka, Tomáš; Novotná, Pavlína; Urbanová, Marie; Safařík, Martin; Buděšínský, Miloš; Tichý, Miloš; Bednárová, Lucie; Baumruk, Vladimír; Maloň, Petr
2013-08-22
We investigate amide nonplanarity in vibrational optical activity (VOA) spectra of tricyclic spirodilactams 5,8-diazatricyclo[6,3,0,0(1,5)]undecan-4,9-dione (I) and its 6,6',7,7'-tetradeuterio derivative (II). These rigid molecules constrain amide groups to nonplanar geometries with twisted pyramidal arrangements of bonds to amide nitrogen atoms. We have collected a full range vibrational circular dichroism (VCD) and Raman optical activity (ROA) spectra including signals of C-H and C-D stretching vibrations. We report normal-mode analysis and a comparison of calculated to experimental VCD and ROA. The data provide band-to-band assignment and offer a possibility to evaluate roles of constrained nonplanar tertiary amide groups and rigid chiral skeletons. Nonplanarity shows as single-signed VCD and ROA amide I signals, prevailing the couplets expected to arise from the amide-amide interaction. Amide-amide coupling dominates amide II (mainly C'-N stretching, modified in tertiary amides by the absence of a N-H bond) transitions (strong couplet in VCD, no significant ROA) probably due to the close proximity of amide nitrogen atoms. At lower wavenumbers, ROA spectra exhibit another likely manifestation of amide nonplanarity, showing signals of amide V (δ(oop)(N-C) at ~570 cm(-1)) and amide VI (δ(oop)(C'═O) at ~700 cm(-1) and ~650 cm(-1)) vibrations.
Structural rigidity in the capsid assembly of cowpea chlorotic mottle virus
Energy Technology Data Exchange (ETDEWEB)
Hespenheide, B M [Department of Physics and Astronomy, Arizona State University, PO Box 871504, Tempe, AZ 85287-1504 (United States); Jacobs, D J [Department of Physics and Astronomy, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8268 (United States); Thorpe, M F [Department of Physics and Astronomy, Arizona State University, PO Box 871504, Tempe, AZ 85287-1504 (United States)
2004-11-10
The cowpea chlorotic mottle virus (CCMV) has a protein cage, or capsid, which encloses its genetic material. The structure of the capsid consists of 180 copies of a single protein that self-assemble inside a cell to form a complete capsid with icosahedral symmetry. The icosahedral surface can be naturally divided into pentagonal and hexagonal faces, and the formation of either of these faces has been proposed to be the first step in the capsid assembly process. We have used the software FIRST to analyse the rigidity of pentameric and hexameric substructures of the complete capsid to explore the viability of certain capsid assembly pathways. FIRST uses the 3D pebble game to determine structural rigidity, and a brief description of this algorithm, as applied to body-bar networks, is given here. We find that the pentameric substructure, which corresponds to a pentagonal face on the icosahedral surface, provides the best structural properties for nucleating the capsid assembly process, consistent with experimental observations.
Nucleosome–nucleosome interactions via histone tails and linker DNA regulate nuclear rigidity
Shimamoto, Yuta; Tamura, Sachiko; Masumoto, Hiroshi; Maeshima, Kazuhiro
2017-01-01
Cells, as well as the nuclei inside them, experience significant mechanical stress in diverse biological processes, including contraction, migration, and adhesion. The structural stability of nuclei must therefore be maintained in order to protect genome integrity. Despite extensive knowledge on nuclear architecture and components, however, the underlying physical and molecular mechanisms remain largely unknown. We address this by subjecting isolated human cell nuclei to microneedle-based quantitative micromanipulation with a series of biochemical perturbations of the chromatin. We find that the mechanical rigidity of nuclei depends on the continuity of the nucleosomal fiber and interactions between nucleosomes. Disrupting these chromatin features by varying cation concentration, acetylating histone tails, or digesting linker DNA results in loss of nuclear rigidity. In contrast, the levels of key chromatin assembly factors, including cohesin, condensin II, and CTCF, and a major nuclear envelope protein, lamin, are unaffected. Together with in situ evidence using living cells and a simple mechanical model, our findings reveal a chromatin-based regulation of the nuclear mechanical response and provide insight into the significance of local and global chromatin structures, such as those associated with interdigitated or melted nucleosomal fibers. PMID:28428255
An Experimental Comparison Between Flexible and Rigid Airfoils at Low Reynolds Numbers
Uzodinma, Jaylon; Macphee, David
2017-11-01
This study uses experimental and computational research methods to compare the aerodynamic performance of rigid and flexible airfoils at a low Reynolds number throughout varying angles of attack. This research can be used to improve the design of small wind turbines, micro-aerial vehicles, and any other devices that operate at low Reynolds numbers. Experimental testing was conducted in the University of Alabama's low-speed wind tunnel, and computational testing was conducted using the open-source CFD code OpenFOAM. For experimental testing, polyurethane-based (rigid) airfoils and silicone-based (flexible) airfoils were constructed using acrylic molds for NACA 0012 and NACA 2412 airfoil profiles. Computer models of the previously-specified airfoils were also created for a computational analysis. Both experimental and computational data were analyzed to examine the critical angles of attack, the lift and drag coefficients, and the occurrence of laminar boundary separation for each airfoil. Moreover, the computational simulations were used to examine the resulting flow fields, in order to provide possible explanations for the aerodynamic performances of each airfoil type. EEC 1659710.
Concentration fluctuations in miscible polymer blends: Influence of temperature and chain rigidity
International Nuclear Information System (INIS)
Dudowicz, Jacek; Freed, Karl F.; Douglas, Jack F.
2014-01-01
In contrast to binary mixtures of small molecule fluids, homogeneous polymer blends exhibit relatively large concentration fluctuations that can strongly affect the transport properties of these complex fluids over wide ranges of temperatures and compositions. The spatial scale and intensity of these compositional fluctuations are studied by applying Kirkwood-Buff theory to model blends of linear semiflexible polymer chains with upper critical solution temperatures. The requisite quantities for determining the Kirkwood-Buff integrals are generated from the lattice cluster theory for the thermodynamics of the blend and from the generalization of the random phase approximation to compressible polymer mixtures. We explore how the scale and intensity of composition fluctuations in binary blends vary with the reduced temperature τ ≡ (T − T c )/T (where T c is the critical temperature) and with the asymmetry in the rigidities of the components. Knowledge of these variations is crucial for understanding the dynamics of materials fabricated from polymer blends, and evidence supporting these expectations is briefly discussed
't Hooft, Gerardus; Witten, Edward
2005-01-01
In his later years, Einstein sought a unified theory that would extend general relativity and provide an alternative to quantum theory. There is now talk of a "theory of everything"; fifty years after his death, how close are we to such a theory? (3 pages)
Dynamic stability of slender columns with semi-rigid connections under periodic axial load: theory
Directory of Open Access Journals (Sweden)
Oliver Giraldo-Londoño
2014-01-01
Full Text Available La estabilidad dinámica de una columna elástica prismática esbelta con conexiones semirrígidas en ambos extremos de rigidez idéntica y con desplazamiento lateral entre los dos extremos totalmente inhibido sujetos a cargas axiales paramétricos incluyendo los efectos combinados de inercia rotacional y amortiguación externas se investiga de una manera clásica. Expresiones cerradas que se pueden utilizar para predecir las regiones de inestabilidad dinámica de columnas esbeltas son desarrolladas haciendo uso de la teoría de Floquet. La solución propuesta es capaz de capturar el fenómeno de estabilidad en columnas sometidas a cargas axiales periódicas utilizando un solo elemento de columna. El método propuesto y las ecuaciones correspondientes se pueden utilizar para investigar los efectos del amortiguamiento, la inercia rotacional de la columna, y las conexiones semirrígidas en el análisis de estabilidad de columnas esbeltas sometidas a cargas axiales periódicas. Los efectos producidos por las deformaciones por cizallamiento a lo largo de la columna, así como los producidos por la inercia axial, el acoplamiento entre las deflexiones longitudinales y transversales y la curvatura no se tienen en cuenta. Estudios de sensibilidad que muestran los efectos de la inercia rotacional, el amortiguamiento y las conexiones semi-rígidas en la estabilidad dinámica de columnas sometidas a cargas axiales paramétricas son presentados en una publicación adjunta.
Simplified non-linear time-history analysis based on the Theory of Plasticity
DEFF Research Database (Denmark)
Costa, Joao Domingues
2005-01-01
This paper aims at giving a contribution to the problem of developing simplified non-linear time-history (NLTH) analysis of structures which dynamical response is mainly governed by plastic deformations, able to provide designers with sufficiently accurate results. The method to be presented...... is based on the Theory of Plasticity. Firstly, the formulation and the computational procedure to perform time-history analysis of a rigid-plastic single degree of freedom (SDOF) system are presented. The necessary conditions for the method to incorporate pinching as well as strength degradation...
Energy Technology Data Exchange (ETDEWEB)
Zhu, Kai-Li [Gansu Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Key Laboratory of Eco-environment-related Polymer Materials, Ministry of Education, Northwest Normal University, Lanzhou, 730070 Gansu (China); College of Chemistry and Life Science, Gansu Normal University for Nationalities, Hezuo, 747000 Gansu (China); Liu, Le-Yan [College of Chemistry and Life Science, Gansu Normal University for Nationalities, Hezuo, 747000 Gansu (China); Geng, Zhi-Yuan, E-mail: zhiyuangeng@126.com [Gansu Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Key Laboratory of Eco-environment-related Polymer Materials, Ministry of Education, Northwest Normal University, Lanzhou, 730070 Gansu (China); Yan, Pen-Ji; Lu, Yan-Hong; Liu, Rui-Rui [Gansu Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Key Laboratory of Eco-environment-related Polymer Materials, Ministry of Education, Northwest Normal University, Lanzhou, 730070 Gansu (China)
2015-07-15
Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations have been carried out to explore the underlying origin of merits for rigid π-spacer based on reference dyes C255 and C254. The results demonstrate that higher short-circuit current density (J{sub SC}) of C255 is primarily ascribed to the lower EBE, while the biggish short-circuit current density (V{sub OC}) mainly originates from the larger μ{sub normal} compared to C254. Besides, a novel index integral of overlap between hole and electron (S) is firstly introduced to quantitatively estimate the facility of intramolecular charge transfer (ICT) and preliminarily confirmed to be effective for the research target of this work. Furthermore, three series of dyes (C-series, A-series, AC-series) have been designed and characterized to screen promising sensitizer candidates and design strategies, while delightful results have been achieved including 6 promising candidates, design stratagem on efficiently reducing the charge recombination and combinational tactics on screening new dyes with excellent spectral properties or outstanding DSSC performance. - Graphical abstract: Display Omitted - Highlights: • Novel S index was introduced in and confirmed to be effective to estimate ICT. • The merits of rigid π bridge have been theoretically revealed. • Six promising candidates have been screened out. • New strategy on reduce charge recombination was reported. • Novel combinational tactics were acquired and justified to be feasible.
Geometry of supersymmetric gauge theories
International Nuclear Information System (INIS)
Gieres, F.
1988-01-01
This monograph gives a detailed and pedagogical account of the geometry of rigid superspace and supersymmetric Yang-Mills theories. While the core of the text is concerned with the classical theory, the quantization and anomaly problem are briefly discussed following a comprehensive introduction to BRS differential algebras and their field theoretical applications. Among the treated topics are invariant forms and vector fields on superspace, the matrix-representation of the super-Poincare group, invariant connections on reductive homogeneous spaces and the supermetric approach. Various aspects of the subject are discussed for the first time in textbook and are consistently presented in a unified geometric formalism
(Non-)decoupled supersymmetric field theories
Energy Technology Data Exchange (ETDEWEB)
Pietro, Lorenzo Di [Department of Particle Physics and Astrophysics,Weizmann Institute of Science, Rehovot 76100 (Israel); Dine, Michael [Santa Cruz Institute for Particle Physics and Department of Physics,Santa Cruz CA 95064 (United States); Komargodski, Zohar [Department of Particle Physics and Astrophysics,Weizmann Institute of Science, Rehovot 76100 (Israel)
2014-04-10
We study some consequences of coupling supersymmetric theories to (super)gravity. To linear order, the couplings are determined by the energy-momentum supermultiplet. At higher orders, the couplings are determined by contact terms in correlation functions of the energy-momentum supermultiplet. We focus on the couplings of one particular field in the supergravity multiplet, the auxiliary field M. We discuss its linear and quadratic (seagull) couplings in various supersymmetric theories. In analogy to the local renormalization group formalism (http://dx.doi.org/10.1016/0370-2693(89)90729-6; http://dx.doi.org/10.1016/0550-3213(90)90584-Z; http://dx.doi.org/10.1016/0550-3213(91)80030-P), we provide a prescription for how to fix the quadratic couplings. They generally arise at two-loops in perturbation theory. We check our prescription by explicitly computing these couplings in several examples such as mass-deformed N=4 and in the Coulomb phase of some theories. These couplings affect the Lagrangians of rigid supersymmetric theories in curved space. In addition, our analysis leads to a transparent derivation of the phenomenon known as Anomaly Mediation. In contrast to previous approaches, we obtain both the gaugino and scalar masses of Anomaly Mediation by relying just on classical, minimal supergravity and a manifestly local and supersymmetric Wilsonian point of view. Our discussion naturally incorporates the connection between Anomaly Mediation and supersymmetric AdS{sub 4} Lagrangians. This note can be read without prior familiarity with Anomaly Mediated Supersymmetry Breaking (AMSB)
(Non-)decoupled supersymmetric field theories
International Nuclear Information System (INIS)
Pietro, Lorenzo Di; Dine, Michael; Komargodski, Zohar
2014-01-01
We study some consequences of coupling supersymmetric theories to (super)gravity. To linear order, the couplings are determined by the energy-momentum supermultiplet. At higher orders, the couplings are determined by contact terms in correlation functions of the energy-momentum supermultiplet. We focus on the couplings of one particular field in the supergravity multiplet, the auxiliary field M. We discuss its linear and quadratic (seagull) couplings in various supersymmetric theories. In analogy to the local renormalization group formalism (http://dx.doi.org/10.1016/0370-2693(89)90729-6; http://dx.doi.org/10.1016/0550-3213(90)90584-Z; http://dx.doi.org/10.1016/0550-3213(91)80030-P), we provide a prescription for how to fix the quadratic couplings. They generally arise at two-loops in perturbation theory. We check our prescription by explicitly computing these couplings in several examples such as mass-deformed N=4 and in the Coulomb phase of some theories. These couplings affect the Lagrangians of rigid supersymmetric theories in curved space. In addition, our analysis leads to a transparent derivation of the phenomenon known as Anomaly Mediation. In contrast to previous approaches, we obtain both the gaugino and scalar masses of Anomaly Mediation by relying just on classical, minimal supergravity and a manifestly local and supersymmetric Wilsonian point of view. Our discussion naturally incorporates the connection between Anomaly Mediation and supersymmetric AdS 4 Lagrangians. This note can be read without prior familiarity with Anomaly Mediated Supersymmetry Breaking (AMSB)
Penland, Patrick R.
Three papers are presented which delineate the foundation of theory and principles which underlie the research and instructional approach to communications at the Graduate School of Library and Information Science, University of Pittsburgh. Cybernetic principles provide the integration, and validation is based in part on a situation-producing…
Directory of Open Access Journals (Sweden)
Ahmed Abbas Jasim Alsabbagh
2016-03-01
Full Text Available Rigid pavements provide durable service life and have remarkable application under heavy traffic loading. But, though the rigid pavements have several advantages, it suffers from some disadvantages that are relating with concrete is brittle material. One solution have been carried out in order to overcome this problem is using fibers reinforced to improve tensile strength and provides ductility. The main objective of this study is to investigating the effects of using fiber reinforced concrete (Polyvinyl alcohol and steel fiber in Rigid Pavements on Compressive and Flexural Properties. The study results shown the compressive strength has been increased by (20% when adding (0.5% of Polyvinyl alcohol concrete mixture. While modulus of elasticity has been decreasing by (23% when adding the same content of Polyvinyl alcohol. On the other hand, the study results show that using steel fiber (1.5% in concrete mixtures increase compressive strength by more than 145%.However modulus of elasticity slightly decrease. Also the addition of PVA fiber by 0.5% increase of about (51% in the Modulus of Rupture, while using steel fiber (1.5% increase Modulus of Rupture by more than (24%.
Technical rigidity and appropriate technology in less-developed countries
Energy Technology Data Exchange (ETDEWEB)
Forsyth, D J.C. [Univ. of Strathyclyde, England; McBain, N S; Solomon, R F
1980-05-01
The extent to which the use of capital-intensive methods in LDCs can properly be ascribed to the inherent rigidity of the factor proportions embodied in modern technology - rather than to distortions and aberrrations in the process of technology choice - is still a matter of considerable uncertainty after two decades of debate. In this study, an engineering-based index is developed to summarize the opportunities for, and barriers to, substitution of labor for capital in a wide range of industries. The index is used to compare the technology actually installed in manufacturing in Ghana, the Philippines, Turkey, and Malaysia with the feasible alternatives. The finding that opportunities for use of labor-intensive methods are to a large extent exploited is interpreted as casting doubt on the ability of even the most appropriate choice from currently feasible technologies to reduce unemployment significantly. 46 references, 5 figures, 6 tables.
On the dynamics of semi-rigid chains
International Nuclear Information System (INIS)
Rodriguez Talavera, R.; Alexander-Katz, R.
1993-01-01
The dynamics of a semi-rigid polymer chain is studied. The force structure of the chain is derived from the statistics generated through a Wiener measure whose end-to-end distance is that of a Kratky-Porod chain. Additionally, the dissipative terms in the equation of motion will contain, besides the usual Stokes' term, a non-local friction term (internal viscosity) which is quadratic in the normal mode q, in order to take into account the resistance to changes in curvature. The analytical shape of this term is the same as the one introduced by Edwards and Freed. We show that this model of stiff chain reproduces both asymptotic limits: the flexible and the rod limits for the elastic moduli. A form for the internal viscosity coefficient is deduced from a phenomenological approach, which has the right solvent viscosity dependency as obtained by MacInnes. (Author)
Radiographic evaluation of fracture healing after rigid plate fixation
International Nuclear Information System (INIS)
Paavolainen, P.; Karaharju, E.; Slaetis, P.; Waris, P.
1981-01-01
Experimental osteotomies were made in 35 rabbit tibio-fibular bones and fixed with rigid stainless steel osteosynthesis plates (DCP/ASIF). The radiographic and histopathologic appearances in the healing osteotomies and adjacent bone were analysed at intervals from 3 up to 24 weeks postoperatively. Radiologically the osteotomy had closed at 9 weeks and microscopically this could be confirmed as longitudinal orientation of the cutter heads across the osteotomy gap with longitudinal orientation of the bone structure. The healing of the osteotomy was accompanied by gross structural changes in the adjacent cortical bone with loss of intracortical and subendosteal osteons, cementing lines and intermediate tissue between the osteons. This was characterized by decreasing attenuation of the cortical bone after healing of the osteotomy and should clinically be regarded as an indication for removal of the implant. (Auth.)
Persistence-Driven Durotaxis: Generic, Directed Motility in Rigidity Gradients
Novikova, Elizaveta A.; Raab, Matthew; Discher, Dennis E.; Storm, Cornelis
2017-02-01
Cells move differently on substrates with different rigidities: the persistence time of their motion is higher on stiffer substrates. We show that this behavior—in and of itself—results in a net flux of cells directed up a soft-to-stiff gradient. Using simple random walk models with varying persistence and stochastic simulations, we characterize the propensity to move in terms of the durotactic index also measured in experiments. A one-dimensional model captures the essential features and highlights the competition between diffusive spreading and linear, wavelike propagation. Persistence-driven durokinesis is generic and may be of use in the design of instructive environments for cells and other motile, mechanosensitive objects.
JOINT RIGIDITY ASSESSMENT WITH PIEZOELECTRIC WAFERS AND ACOUSTIC WAVES
International Nuclear Information System (INIS)
Montoya, Angela C.; Maji, Arup K.
2010-01-01
There has been an interest in the development of rapid deployment satellites. In a modular satellite design, different panels of specific functions can be pre-manufactured. The satellite can then be assembled and tested just prior to deployment. Traditional vibration testing is time-consuming and expensive. An alternative test method to evaluate the connection between two plates will be proposed. The method investigated and described employs piezoelectric wafers to induce and sense lamb waves in two aluminum plates, which were joined by steel brackets to form an 'L-Style' joint. Lamb wave behavior and piezoelectric material properties will be discussed; the experimental setup and results will be presented. A set of 4 piezoelectric ceramic wafers were used alternately as source and sensor. The energy transmitted was shown to correlate with a mechanical assessment of the joint, demonstrating that this method of testing is a feasible and reliable way to inspect the rigidity of joints.
Capital-Skill Complementarity and Rigid Relative Wages
DEFF Research Database (Denmark)
Rose Skaksen, Jan; Sørensen, Anders
2004-01-01
be countercyclical. The labor market is competitivein the United States and therefore relative wages of skilled labor are expected to becountercyclical. We find that the business cycle development of the two economiesis consistent with capital-skill complementarity.Keywords: capital-skill complementarity, relative......The relative demand for skills has increased considerably in many OECD countriesduring recent decades. This development is potentially explained by capital-skillcomplementarity and high growth rates of capital equipment. When productionfunctions are characterized by capital-skill complementarity......, relative wages and employmentof skilled labor are countercyclical because capital equipment is a quasi-fixed factor in the short run. The exact behavior of the two variables depends onrelative wage flexibility. Relative wages are rigid in Denmark, implying that the employmentshare of skills should...
Percutaneous antegrade ureteric stent removal using a rigid alligator forceps.
LENUS (Irish Health Repository)
Given, M F
2008-12-01
To evaluate the safety and efficacy of percutaneous antegrade ureteric stent removal using a rigid alligator forceps. Twenty patients were included in our study. Indications for ureteric stent insertion included stone disease (n = 7), malignancy (n = 8) and transplant anastomotic strictures (n = 5). Stent retrieval was carried out for proximal stent placement\\/migration in seven patients and encrustation in the remaining 13. Twenty-two stents were successfully retrieved in 20 patients. There was one technical failure (5%). There were no major complications. We had four minor complications, which included nephrostomy site pain (n = 2), periprocedural sepsis (n = 1) and a small urinoma (n = 1). All patients settled with conservative management. Percutaneous radiologically guided antegrade ureteric stent removal with an alligator forceps is safe and effective, particularly when initial surgical removal has failed.
Dynamics of Rigid Bodies and Flexible Beam Structures
DEFF Research Database (Denmark)
Nielsen, Martin Bjerre
of rigid bodies and flexible beam structures with emphasis on the rotational motion. The first part deals with motion in a rotating frame of reference. A novel approach where the equations of motion are formulated in a hybrid state-space in terms of local displacements and global velocities is presented...... quaternion parameters or nine convected base vector components. In both cases, the equations of motion are obtained via Hamilton’s equations by including the kinematic constraints associated with the redundant rotation description by means of Lagrange multipliers. A special feature of the formulation...... of the global components of the position vectors and associated convected base vectors for the element nodes. The kinematics is expressed in a homogeneous quadratic form and the constitutive stiffness is derived from complementary energy of a set of equilibrium modes, each representing a state of constant...
Damageable contact between an elastic body and a rigid foundation
Campo, M.; Fernández, J. R.; Silva, A.
2009-02-01
In this work, the contact problem between an elastic body and a rigid obstacle is studied, including the development of material damage which results from internal compression or tension. The variational problem is formulated as a first-kind variational inequality for the displacements coupled with a parabolic partial differential equation for the damage field. The existence of a unique local weak solution is stated. Then, a fully discrete scheme is introduced using the finite element method to approximate the spatial variable and an Euler scheme to discretize the time derivatives. Error estimates are derived on the approximate solutions, from which the linear convergence of the algorithm is deduced under suitable regularity conditions. Finally, three two-dimensional numerical simulations are performed to demonstrate the accuracy and the behaviour of the scheme.
International Nuclear Information System (INIS)
Inci, Ercan; Turkay, Rustu; Nalbant, Mustafa Orhan; Yenice, Mustafa Gurkan; Tugcu, Volkan
2017-01-01
Highlights: • Shear wave elastography is a new method that can calculate tissue stiffness. • The structure of corpus cavernosum is mainly responsible for erectile function. • The corpus cavernosum rigidity can be used to evaluate tissue structure. • Shear wave elastography can provide information regarding penile structure. - Abstract: Objective: The goal of this study was to measure corpus cavernosum (CC) penis rigidity with shear wave elastography (SWE) in healthy volunteers and to evaluate the change of rigidity with age. Methods: SWE was performed in 60 healthy volunteers (age range 20–71, mean 47 ± 12,83 years). Volunteers were divided into 2 groups by age (Group 1 age <50, group 2 age ≥50). We assessed SWE in 3 parts of penis (proximal, middle and glans penis) on both sides of CC. All values of SWE (in kilo Pascal) were noted along with volunteers’ ages. The measurements were done both with transverse (T) and longitudinal (L) sections. We compared all SW values of penis parts and their alterations with age. Results: The shear wave elastography values of CC penis increased with increasing age (p < 0,01). There was no significant difference between both sides of CC penis (p < 0,05). We calculated no significant difference between T and L sections of all parts of penis (p < 0,05). Conclusions: SWE can provide noninvasive quantitative data of CC penis rigidity and its alteration with age. These data may create a new approach in the evaluation process and treatment options for penile pathologies.
Energy Technology Data Exchange (ETDEWEB)
Inci, Ercan, E-mail: ercan@inci.com [Radiology Department, University of Health Sciences Istanbul Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Bakirkoy, Istanbul (Turkey); Turkay, Rustu, E-mail: rustuturkay@hotmail.com [Radiology Department, University of Health Sciences Istanbul Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Bakirkoy, Istanbul (Turkey); Nalbant, Mustafa Orhan, E-mail: musnalbant88@hotmail.com [Radiology Department, University of Health Sciences Istanbul Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Bakirkoy, Istanbul (Turkey); Yenice, Mustafa Gurkan, E-mail: yenicegurkan@gmail.com [Urology Department, University of Health Sciences Istanbul Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Bakirkoy, Istanbul (Turkey); Tugcu, Volkan, E-mail: volkantugcu@yahoo.com [Urology Department, University of Health Sciences Istanbul Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Bakirkoy, Istanbul (Turkey)
2017-04-15
Highlights: • Shear wave elastography is a new method that can calculate tissue stiffness. • The structure of corpus cavernosum is mainly responsible for erectile function. • The corpus cavernosum rigidity can be used to evaluate tissue structure. • Shear wave elastography can provide information regarding penile structure. - Abstract: Objective: The goal of this study was to measure corpus cavernosum (CC) penis rigidity with shear wave elastography (SWE) in healthy volunteers and to evaluate the change of rigidity with age. Methods: SWE was performed in 60 healthy volunteers (age range 20–71, mean 47 ± 12,83 years). Volunteers were divided into 2 groups by age (Group 1 age <50, group 2 age ≥50). We assessed SWE in 3 parts of penis (proximal, middle and glans penis) on both sides of CC. All values of SWE (in kilo Pascal) were noted along with volunteers’ ages. The measurements were done both with transverse (T) and longitudinal (L) sections. We compared all SW values of penis parts and their alterations with age. Results: The shear wave elastography values of CC penis increased with increasing age (p < 0,01). There was no significant difference between both sides of CC penis (p < 0,05). We calculated no significant difference between T and L sections of all parts of penis (p < 0,05). Conclusions: SWE can provide noninvasive quantitative data of CC penis rigidity and its alteration with age. These data may create a new approach in the evaluation process and treatment options for penile pathologies.
A rigid motion correction method for helical computed tomography (CT)
International Nuclear Information System (INIS)
Kim, J-H; Kyme, A; Fulton, R; Nuyts, J; Kuncic, Z
2015-01-01
We propose a method to compensate for six degree-of-freedom rigid motion in helical CT of the head. The method is demonstrated in simulations and in helical scans performed on a 16-slice CT scanner. Scans of a Hoffman brain phantom were acquired while an optical motion tracking system recorded the motion of the bed and the phantom. Motion correction was performed by restoring projection consistency using data from the motion tracking system, and reconstructing with an iterative fully 3D algorithm. Motion correction accuracy was evaluated by comparing reconstructed images with a stationary reference scan. We also investigated the effects on accuracy of tracker sampling rate, measurement jitter, interpolation of tracker measurements, and the synchronization of motion data and CT projections. After optimization of these aspects, motion corrected images corresponded remarkably closely to images of the stationary phantom with correlation and similarity coefficients both above 0.9. We performed a simulation study using volunteer head motion and found similarly that our method is capable of compensating effectively for realistic human head movements. To the best of our knowledge, this is the first practical demonstration of generalized rigid motion correction in helical CT. Its clinical value, which we have yet to explore, may be significant. For example it could reduce the necessity for repeat scans and resource-intensive anesthetic and sedation procedures in patient groups prone to motion, such as young children. It is not only applicable to dedicated CT imaging, but also to hybrid PET/CT and SPECT/CT, where it could also ensure an accurate CT image for lesion localization and attenuation correction of the functional image data. (paper)
Inertial modes of rigidly rotating neutron stars in Cowling approximation
International Nuclear Information System (INIS)
Kastaun, Wolfgang
2008-01-01
In this article, we investigate inertial modes of rigidly rotating neutron stars, i.e. modes for which the Coriolis force is dominant. This is done using the assumption of a fixed spacetime (Cowling approximation). We present frequencies and eigenfunctions for a sequence of stars with a polytropic equation of state, covering a broad range of rotation rates. The modes were obtained with a nonlinear general relativistic hydrodynamic evolution code. We further show that the eigenequations for the oscillation modes can be written in a particularly simple form for the case of arbitrary fast but rigid rotation. Using these equations, we investigate some general characteristics of inertial modes, which are then compared to the numerically obtained eigenfunctions. In particular, we derive a rough analytical estimate for the frequency as a function of the number of nodes of the eigenfunction, and find that a similar empirical relation matches the numerical results with unexpected accuracy. We investigate the slow rotation limit of the eigenequations, obtaining two different sets of equations describing pressure and inertial modes. For the numerical computations we only considered axisymmetric modes, while the analytic part also covers nonaxisymmetric modes. The eigenfunctions suggest that the classification of inertial modes by the quantum numbers of the leading term of a spherical harmonic decomposition is artificial in the sense that the largest term is not strongly dominant, even in the slow rotation limit. The reason for the different structure of pressure and inertial modes is that the Coriolis force remains important in the slow rotation limit only for inertial modes. Accordingly, the scalar eigenequation we obtain in that limit is spherically symmetric for pressure modes, but not for inertial modes
Psychological Prices and Price Rigidity in Grocery Retailing: Analysis of German Scanner Data
Herrmann, Roland; Moeser, Anke
2005-01-01
A substantial degree of price rigidity has been reported for branded foods in various studies with scanner data. One possible explanation for price rigidity is the existence of psychological pricing points. We analyze to which extent psychological pricing plays a role in grocery retailing and whether it contributes to price rigidity of branded foods in Germany. Psychological pricing defined here as just-below-the-round-figure-pricing is empirically analyzed with scanner data of weekly prices ...
Use of beam probes for rigidity calibration of the A1900 fragment separator
Energy Technology Data Exchange (ETDEWEB)
Ginter, T.N. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Farinon, F. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Baumann, T. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Hausmann, M. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Kwan, E.; Naviliat Cuncic, O. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Portillo, M. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Rogers, A.M.; Stetson, J.; Sumithrarachchi, C. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Villari, A.C.C. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Williams, S.J. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States)
2016-06-01
Use of a beam-based approach is presented for establishing a rigidity calibration for the A1900 fragment separator located at the National Superconducting Cyclotron Laboratory. Also presented is why an alternative approach to the rigidity calibration – using detailed field maps of individual magnetic components – is not a feasible basis for deriving an accurate calibration. The level of accuracy achieved for the rigidity calibration is ±0.1%.
Conlon, Joseph
2016-01-01
Is string theory a fraud or one of the great scientific advances? Why do so many physicists work on string theory if it cannot be tested? This book provides insight into why such a theory, with little direct experimental support, plays such a prominent role in theoretical physics. The book gives a modern and accurate account of string theory and science, explaining what string theory is, why it is regarded as so promising, and why it is hard to test.
International Nuclear Information System (INIS)
Sitenko, A.
1991-01-01
This book emerged out of graduate lectures given by the author at the University of Kiev and is intended as a graduate text. The fundamentals of non-relativistic quantum scattering theory are covered, including some topics, such as the phase-function formalism, separable potentials, and inverse scattering, which are not always coverded in textbooks on scattering theory. Criticisms of the text are minor, but the reviewer feels an inadequate index is provided and the citing of references in the Russian language is a hindrance in a graduate text
Sensing of substratum rigidity and directional migration by fast-crawling cells
Okimura, Chika; Sakumura, Yuichi; Shimabukuro, Katsuya; Iwadate, Yoshiaki
2018-05-01
Living cells sense the mechanical properties of their surrounding environment and respond accordingly. Crawling cells detect the rigidity of their substratum and migrate in certain directions. They can be classified into two categories: slow-moving and fast-moving cell types. Slow-moving cell types, such as fibroblasts, smooth muscle cells, mesenchymal stem cells, etc., move toward rigid areas on the substratum in response to a rigidity gradient. However, there is not much information on rigidity sensing in fast-moving cell types whose size is ˜10 μ m and migration velocity is ˜10 μ m /min . In this study, we used both isotropic substrata with different rigidities and an anisotropic substratum that is rigid on the x axis but soft on the y axis to demonstrate rigidity sensing by fast-moving Dictyostelium cells and neutrophil-like differentiated HL-60 cells. Dictyostelium cells exerted larger traction forces on a more rigid isotropic substratum. Dictyostelium cells and HL-60 cells migrated in the "soft" direction on the anisotropic substratum, although myosin II-null Dictyostelium cells migrated in random directions, indicating that rigidity sensing of fast-moving cell types differs from that of slow types and is induced by a myosin II-related process.
An evaluation of canonical forms for non-rigid 3D shape retrieval
Pickup, David; Liu, Juncheng; Sun, Xianfang; Rosin, Paul L.; Martin, Ralph R.; Cheng, Zhiquan; Lian, Zhouhui; Nie, Sipin; Jin, Longcun; Shamai, Gil; Sahillioğlu, Yusuf; Kavan, Ladislav
2018-01-01
Canonical forms attempt to factor out a non-rigid shape’s pose, giving a pose-neutral shape. This opens up the\\ud possibility of using methods originally designed for rigid shape retrieval for the task of non-rigid shape retrieval.\\ud We extend our recent benchmark for testing canonical form algorithms. Our new benchmark is used to evaluate a\\ud greater number of state-of-the-art canonical forms, on five recent non-rigid retrieval datasets, within two different\\ud retrieval frameworks. A tota...
Rigid-Plastic Post-Buckling Analysis of Columns and Quadratic Plates
DEFF Research Database (Denmark)
Jönsson, Jeppe
2008-01-01
the compressive load as a function of the transverse displacement. An estimate of the magnitude of the transverse displacement prior to the forming of the collapse mechanism is introduced into the compressive load function, determined by the virtual work equation, thereby revealing a qualified estimate...... yield lines accommodate differential rotations of rigid parts and the area “collapse” yield lines accommodate local area changes of the rigid parts thereby preserving compatibility of the rigid parts of a plate. The approach will be illustrated for rigid plastic column analysis and for a quadratic plate...
Botulinum toxin in myotonia congenita: it does not help against rigidity and pain.
Dressler, Dirk; Adib Saberi, Fereshte
2014-05-01
Botulinum toxin (BT) is a potent local muscle relaxant with analgetic properties. Myotonia congenita (MC) is a genetic disorder producing muscle rigidity and pain. BT injected into the trapezius produced mild paresis, but no effect on rigidity and pain. There were no signs of systemic effects. Lack of BT efficacy on MC rigidity confirms its origin from muscle membrane dysfunction rather than from inappropriate neuromuscular activation. Lack of BT efficacy on pain could be caused by lack of anti-rigidity effect. It could also be due to separate non-muscular pain mechanisms unresponsive to BT.
Indian Academy of Sciences (India)
strongly motivate a detailed search for inflation within string theory, although it has ... between string theory and observations provides a strong incentive for ..... sonably be expected to arise for any system having very many degrees of freedom.
Fermion zero modes and the black-hole hypermultiplet with rigid supersymmetry
International Nuclear Information System (INIS)
Brooks, R.; Kallosh, R.; Ortin, T.
1995-01-01
The gravitini zero modes riding on top of the extreme Reissner-Nordstroem black-hole solution of N=2 supergravity are shown to be normalizable. The gravitini and dilatini zero modes of axion-dilaton extreme black-hole solutions of N=4 supergravity are also given and found to have finite norms. These norms are duality invariant. The finiteness and positivity of the norms in both cases are found to be correlated with the Witten-Israel-Nester construction; however, we have replaced the Witten condition by the pure-spin-3/2 constraint on the gravitini. We compare our calculation of the norms with the calculations which provide the moduli space metric for extreme black holes. The action of the N=2 hypermultiplet with an off-shell central charge describes the solitons of N=2 supergravity. This action, in the Majumdar-Papapetrou multi-black-hole background, is shown to be N=2 rigidly supersymmetric
Bayoumi, Ahmed B; Efe, Ibrahim E; Berk, Selim; Kasper, Ekkehard M; Toktas, Zafer Orkun; Konya, Deniz
2018-03-01
The cervicothoracic junction is a challenging anatomic transition in spine surgery. It is commonly affected by different types of diseases that may significantly impair stability in this region. The seventh cervical vertebra (C7) is an atypical cervical vertebra with unique anatomic features compared to subaxial cervical spine (C3 to C6). C7 has relatively broader laminae, larger pedicles, smaller lateral masses, and a long nonbifid spinous process. These features allow a variety of surgical methods for performing posterior rigid instrumentation in the form of different types of screws, such as lateral mass screws, pedicle screws, transfacet screws, and intralaminar screws. Many biomechanical studies on cadavers have evaluated and compared different types of implants at C7. We reviewed PubMed/Medline by using specific combinations of keywords to summarize previously published articles that examined C7 posterior rigid instrumentation thoroughly in an experimental fashion on patients or cadavers with additional descriptive radiologic parameters for evaluation of the optimum surgical technique for each type. A total of 44 articles were reported, including 22 articles that discussed anatomic considerations (entry points, sagittal and axial trajectories, and features of screws) and another 22 articles that discussed the relevant biomechanical testing at this transitional region if C7 was directly involved in terms of receiving posterior rigid implants. C7 can accommodate different types of screws, which can provide additional benefits and risks based on availability of bony purchase, awareness of surgical technique, biomechanics, and anatomic considerations. Copyright © 2017 Elsevier Inc. All rights reserved.
DEFF Research Database (Denmark)
Brazhe, A.; Fordsmann, J.; Lauritzen, M.
2017-01-01
correction of calcium timelapse imaging data is accurate, can represent non-rigid image distortions, robust to noisy data and allows for fast registration of large videos. The implementation is open-source and is programmed in Python, which provides for easy access and merging into downstream image...
Drawing Out Theory: Art and the Teaching of Political Theory.
Miller, Char R.
2000-01-01
Discusses how to use art in introductory political theory courses. Provides examples of incorporating art to teach political theory, such as examining Machiavelli's "The Prince" and Michelangelo's "David" to understand Florentine (Florence, Italy) political theory. (CMK)
Goldie, Charles M
1991-01-01
This book is an introduction, for mathematics students, to the theories of information and codes. They are usually treated separately but, as both address the problem of communication through noisy channels (albeit from different directions), the authors have been able to exploit the connection to give a reasonably self-contained treatment, relating the probabilistic and algebraic viewpoints. The style is discursive and, as befits the subject, plenty of examples and exercises are provided. Some examples and exercises are provided. Some examples of computer codes are given to provide concrete illustrations of abstract ideas.
International Nuclear Information System (INIS)
Tang, W.M.
2001-01-01
This is a summary of the advances in magnetic fusion energy theory research presented at the 17th International Atomic Energy Agency Fusion Energy Conference from 19 24 October, 1998 in Yokohama, Japan. Theory and simulation results from this conference provided encouraging evidence of significant progress in understanding the physics of thermonuclear plasmas. Indeed, the grand challenge for this field is to acquire the basic understanding that can readily enable the innovations which would make fusion energy practical. In this sense, research in fusion energy is increasingly able to be categorized as fitting well the 'Pasteur's Quadrant' paradigm, where the research strongly couples basic science ('Bohr's Quadrant') to technological impact ('Edison's Quadrant'). As supported by some of the work presented at this conference, this trend will be further enhanced by advanced simulations. Eventually, realistic three-dimensional modeling capabilities, when properly combined with rapid and complete data interpretation of results from both experiments and simulations, can contribute to a greatly enhanced cycle of understanding and innovation. Plasma science theory and simulation have provided reliable foundations for this improved modeling capability, and the exciting advances in high-performance computational resources have further accelerated progress. There were 68 papers presented at this conference in the area of magnetic fusion energy theory
Jing, Jie; Qu, Ai-li; Ding, Xiao-mei; Hei, Yu-na
2015-04-01
To analyze the biomechanical healing process on rigid fixation of sagittal fracture of the mandibular condyle (SFMC), and to provide guidelines for surgical treatment. Three-dimensional finite element model (3D-FEAM) of mandible and condyle was established. The right condyle was simulated as SFMC with 0.1 mm space across the condyle length ways. The 3D-FEAM of rigid fixation was established. The biomechanical factors such as stress distribution of condylar surface, displacement around fracture, stress on the plate and stress shielding were calculated during 0, 4, 8 and 12-week after rigid fixation. The maximum equivalent stress of normal condyle was located at the area of middle 1/3 of condylar neck. The maximum equivalent stress at 0-week after fixation was 23 times than that on normal condyle. They were located at the condylar stump and the plate near inferior punctual areas of fracture line. There were little stress on the other areas. The maximum equivalent stress at 4, 8 and 12-week was approximately 6 times than that on normal condyle. They were located at the areas same as the area at 0-week. There were little stress on the other areas at the condyle. The maximum total displacement and maximum total corner were increased 0.57-0.75 mm and 0.01-0.09° respectively during healing process. The maximum equivalent stress at 0-week on the condylar trump was 5-6 times compared with that at 4, 8, and 12-week. The maximum equivalent stress, maximum total displacement and maximum total corner on the fractured fragment were not changed significantly during healing process. The maximum equivalent stress at 0-week on the plate was 7-9 times compared with that at 4, 8, 12-week. The stress of the condyle and stress shielding of the plate may be the reasons of absorbing and rebuilding on the condyle in healing process of SFMC. The biomechanical parameters increase obviously at 4-week after fixation. Elastic intermaxillary traction is necessary to decrease total displacement
Estimating flexural rigidity and load magnitude required for formation of Ross Island flexure moat
Jha, S.; Harry, D. L.; Wenman, C. P.
2017-12-01
Lithospheric flexural subsidence around Ross Island in West Antarctica led to formation of the Ross Island flexure moat. This subsidence was caused by two major volcanic phases on Ross Island. The first phase saw the first surficial expression of Ross Island and volcanism at Mt. Bird to the north of Ross Island, which lasted from 5.2 - 2.9 Ma. The second phase lasted from 1.78 Ma to present and is comprised of eruptions from Mt. Terror to the east, Mt. Erebus to the west and Hut Point Peninsula (HPP) to the south of Ross Island. Flexural subsidence of the lithosphere due to volcanism on Ross Island led to formation of a sedimentary moat around the island, which is preserved in stratigraphy imaged on seismic reflection profiles. We identified 5 unconformities (from deepest upward Ri, RMU1, RMU2, RMU3, RMU4) in the seismic surveys which correspond to flexural subsidence episodes around Ross Island since early Pliocene. Ri (4.4 Ma) lies near the bottom of the flexural moat and RMU4 near the seafloor and top of the moat fill. These unconformities were used to make isopach maps to constrain flexure modeling of the area. Isopach maps show circular or semi-circular flexure basins around Ross Island which is approximated using a continuous plate, point load flexure model. We used Ri - sea floor isopach to constrain flexure models for 5 profiles centered on 4 volcanic centers and trending radially out of Ross Island. Flexure models along two profiles beginning on Mt. Bird and one profile off HPP show a flexural rigidity range of 1.47 - 6.44 x 1018 Nm with load center of mass on Mt. Bird and on HPP, respectively. A similar model along a profile initiating on Mt. Terror, passing through Mt Erebus and extending west of Ross Island across the moat, yielded a higher flexural rigidity estimate of 2.03 x 1019 Nm with load centered at Mt. Erebus. A flexure model to the north east of Ross Island along a profile beginning at Mt Terror and trending north, provide the highest flexural
Bearing capacity and rigidity of short plastic-concrete-tubal vertical columns under transverse load
Dolzhenko, A. V.; Naumov, A. E.; Shevchenko, A. E.
2018-03-01
The results of mathematical modeling in determining strain-stress distribution parameters of a short plastic-concrete-tubal vertical column under horizontal load as those in vertical constructions are described. Quantitative parameters of strain-stress distribution during vertical and horizontal loads and horizontal stiffness were determined by finite element modeling. The internal stress in the concrete column core was analyzed according to equivalent stress in Mohr theory of failure. It was determined that the bearing capacity of a short plastic- concrete-tubal vertical column is 25% higher in resistibility and 15% higher in rigidness than those of the caseless concrete columns equal in size. Cracks formation in the core of a short plastic-concrete-tubal vertical column happens under significantly bigger horizontal loads with less amount of concrete spent than that in caseless concrete columns. The significant increase of bearing capacity and cracking resistance of a short plastic-concrete-tubal vertical column under vertical and horizontal loads allows recommending them as highly effective and highly reliable structural wall elements in civil engineering.
Two Back Stress Hardening Models in Rate Independent Rigid Plastic Deformation
Yun, Su-Jin
In the present work, the constitutive relations based on the combination of two back stresses are developed using the Armstrong-Frederick, Phillips and Ziegler’s type hardening rules. Various evolutions of the kinematic hardening parameter can be obtained by means of a simple combination of back stress rate using the rule of mixtures. Thus, a wide range of plastic deformation behavior can be depicted depending on the dominant back stress evolution. The ultimate back stress is also determined for the present combined kinematic hardening models. Since a kinematic hardening rule is assumed in the finite deformation regime, the stress rate is co-rotated with respect to the spin of substructure obtained by incorporating the plastic spin concept. A comparison of the various co-rotational rates is also included. Assuming rigid plasticity, the continuum body consists of the elastic deformation zone and the plastic deformation zone to form a hybrid finite element formulation. Then, the plastic deformation behavior is investigated under various loading conditions with an assumption of the J2 deformation theory. The plastic deformation localization turns out to be strongly dependent on the description of back stress evolution and its associated hardening parameters. The analysis for the shear deformation with fixed boundaries is carried out to examine the deformation localization behavior and the evolution of state variables.
iCub Whole-body Control through Force Regulation on Rigid Noncoplanar Contacts
Directory of Open Access Journals (Sweden)
Francesco eNori
2015-03-01
Full Text Available This paper details the implementation on the humanoid robot iCub of state-of-the-art algorithms for whole-body control. We regulate the forces between the robot and its surrounding environment to stabilize a desired robot posture. We assume that the forces and torques are exerted on rigid contacts. The validity of this assumption is guaranteed by constraining the contact forces and torques, e.g. the contact forces must belong to the associated friction cones. The implementation of this control strategy requires to estimate the external forces acting on the robot, and the internal joint torques. We then detail algorithms to obtain these estimations when using a robot with an iCub-like sensor set, i.e. distributed six-axis force-torque sensors and whole-body tactile sensors. A general theory for identifying the robot inertial parameters is also presented. From an actuation standpoint, we show how to implement a joint torque control in the case of DC brushless motors. In addition, the coupling mechanism of the iCub torso is investigated. The soundness of the entire control architecture is validated in a real scenario involving the robot iCub balancing and making contacts at both arms.
Numerical study of acoustically driven bubble cloud dynamics near a rigid wall.
Ma, Jingsen; Hsiao, Chao-Tsung; Chahine, Georges L
2018-01-01
The dynamics of a bubble cloud excited by a sinusoidal pressure field near a rigid wall is studied using a novel Eulerian/Lagrangian two-phase flow model. The effects of key parameters such as the amplitude and frequency of the excitation pressure, the cloud and bubble sizes, the void fraction, and the initial standoff distance on the bubbles' collective behavior and the resulting pressure loads on the nearby wall are investigated. The study shows that nonlinear bubble cloud dynamics becomes more pronounced and results in higher pressure loading at the wall as the excitation pressure amplitude increases. The strongest collective bubble behavior occurs at a preferred resonance frequency. At this resonance frequency, pressure peaks orders of magnitudes higher than the excitation pressure result from the bubble interaction when the amplitude of the pressure excitation is high. The numerically obtained resonance frequency is significantly different from the reported natural frequency of a spherical cloud derived from linear theory, which assumes small amplitude oscillations in an unbounded medium. At high amplitudes of the excitation, the resonance frequency decreases almost linearly with the ratio of excitation pressure amplitude to ambient pressure until the ratio is larger than one. Copyright © 2017 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
V. K. Shatalov
2014-01-01
Full Text Available Outboard elements (arms, towers are widely used in spacecraft structure for setting-out of a payload; their high stiffness-weight ratio provides an opportunity to decrease the mass. The deployment unit is considered as an example of outboard structure. Its strength beams work under special conditions in operation. At the transportation stage beams are under considerable vibration loads. Therefore for increasing the natural resonance frequency it is rational to increase their rigidity. Using the micro-arc oxide coating suggests itself because the modulus of elasticity of the micro-arc oxide coating is more than that of the aluminium alloy. The beams suffer considerable bending load at the step of deploying; therefore the aluminium alloy with the micro-arc oxide coating must have suitable loading capacity, in addition to increased rigidity.Influence of micro-arc oxide coating on the rigidity and strength of tubes f rom aluminium alloy is investigated. It is determined that forming the micro-arc oxide coating on thin-walled tubes with a ratio of the coating area to the cross-section area of more than 25% is the most rational. In this case the rigidity of composite material considerably exceeds the rigidity of the aluminium alloy of the same cross-section while the redistribution of stresses in the surface coating of heterogeneous elasticity cross-section doesn’t cause the sudden increase of stresses. Also forming an attainable thickness of the micro-arc oxide coating on the surface of tube from aluminium alloy will be rational solution because the increase of attainable thickness of the microarc oxide coating provides an opportunity to form it on thick-walled tubes saving an acceptable, in the context of the strength, ratio of the coating area to the overall cross-section area.Micro-arc oxidation is an advanced method to form the wear resistant, resistant to corrosion, heat-shielding and electrically insulating coatings, but depending on the
Mixed Volume and Distance Geometry Techniques for Counting Euclidean Embeddings of Rigid Graphs
I.Z. Emiris; E.P. Tsigaridas; A. Varvitsiotis (Antonios); A. Mucherino (Antonio); C. Lavor; L. Liberti; N. Maculan
2013-01-01
htmlabstractA graph G is called generically minimally rigid in Rd if, for any choice of sufficiently generic edge lengths, it can be embedded in Rd in a finite number of distinct ways, modulo rigid transformations. Here, we deal with the problem of determining tight bounds on the number of such
Non-rigid connector: The wand to allay the stresses on abutment
Banerjee, Saurav; Khongshei, Arlingstone; Gupta, Tapas; Banerjee, Ardhendu
2011-01-01
The use of rigid connectors in 5-unit fixed dental prosthesis with a pier abutment can result in failure of weaker retainer in the long run as the pier abutment acts as a fulcrum. Non-rigid connector placed on the distal aspect of pier seems to reduce potentially excess stress concentration on the pier abutment.
Mental set and creative thought in social conflict : Threat rigidity versus motivated focus
De Dreu, Carsten K. W.; Nijstad, Bernard A.
According to the traditional threat-rigidity reasoning, people in social conflict will be less flexible, less creative, more narrow-minded, and more rigid in their thinking when they adopt a conflict rather than a cooperation mental set. The authors propose and test an alternative, motivated focus
On the rigidity of rank gradient in a group of intermediate growth
Grigorchuk, Rostislav; Kravchenko, Rostyslav
2018-01-01
We introduce and investigate the rigidity property of rank gradient in the case of the group $\\mathcal G$ of intermediate growth constructed by the first author. We show that $\\mathcal G$ is normally $(f,g)$-RG rigid where $f(n)=\\log(n)$ and $g(n) =\\log(\\log(n)).$
Risk of perforation using rigid oesophagoscopy in the distal part of oesophagus
DEFF Research Database (Denmark)
Wennervaldt, Kasper; Melchiors, Jacob
2012-01-01
Endoscopic examination and treatment of disorders in the oesophagus have been a part of the otolaryngological specialty since the introduction of the rigid endoscope. Today, both flexible and rigid oesophagoscopy (RO) is used to that end. The aim of this study was to evaluate the safety of the RO....
21 CFR 178.3790 - Polymer modifiers in semirigid and rigid vinyl chloride plastics.
2010-04-01
... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polymer modifiers in semirigid and rigid vinyl...: ADJUVANTS, PRODUCTION AIDS, AND SANITIZERS Certain Adjuvants and Production Aids § 178.3790 Polymer modifiers in semirigid and rigid vinyl chloride plastics. The polymers identified in paragraph (a) of this...
International Nuclear Information System (INIS)
Krashchenko, V.P.; Statsenko, V.E.; Rudnitskij, N.P.
1984-01-01
Investigation procedures are described for rigidity of testing machines and mechanical properties of tantalum and nickel in the temperature range 293-1873K. Temperature dependences are presented for strength characteristics of the investigated materials obtained with the use of installations of different rigidity. Dependence analysis is carried out and recommendations are given as to the characteristics application
Evolution of flexibility and rigidity in retaliatory punishment.
Morris, Adam; MacGlashan, James; Littman, Michael L; Cushman, Fiery
2017-09-26
Natural selection designs some social behaviors to depend on flexible learning processes, whereas others are relatively rigid or reflexive. What determines the balance between these two approaches? We offer a detailed case study in the context of a two-player game with antisocial behavior and retaliatory punishment. We show that each player in this game-a "thief" and a "victim"-must balance two competing strategic interests. Flexibility is valuable because it allows adaptive differentiation in the face of diverse opponents. However, it is also risky because, in competitive games, it can produce systematically suboptimal behaviors. Using a combination of evolutionary analysis, reinforcement learning simulations, and behavioral experimentation, we show that the resolution to this tension-and the adaptation of social behavior in this game-hinges on the game's learning dynamics. Our findings clarify punishment's adaptive basis, offer a case study of the evolution of social preferences, and highlight an important connection between natural selection and learning in the resolution of social conflicts.
Obstacles to developing sustainable cities: the real estate rigidity trap
Directory of Open Access Journals (Sweden)
V. Kelly Turner
2017-06-01
Full Text Available Sprawl patterns of urbanization have large environmental consequences, and sustainable alternatives to conventional urban patterns of development have been promoted by a subset of planners, design professionals, and municipalities. These alternatives have not been widely adopted among real estate developers, actors with large influence over urban form and function. Existing explanations for this failure enumerate market and regulatory barriers but do not sufficiently describe the institutional structures that allow conventional approaches to prevail. A failure of real estate developers to adopt alternative forms of development can best be described in terms of a rigidity trap. Specifically, norms of practice within the real estate development industry combine with market and regulatory factors to favor existing practices and limit innovation. Moreover, these institutional factors also buffer the real estate development industry from feedback mechanisms and external signals that might otherwise trigger adaptation. Addressing the environmental consequences of urbanization not only requires novel approaches to urban design, but will also necessitate addressing systemic pathologies in the design implementation process.
Ultimate Lateral Capacity of Rigid Pile in c- φ Soil
Zhang, Wei-min
2018-03-01
To date no analytical solution of the pile ultimate lateral capacity for the general c- φ soil has been obtained. In the present study, a new dimensionless embedded ratio was proposed and the analytical solutions of ultimate lateral capacity and rotation center of rigid pile in c- φ soils were obtained. The results showed that both the dimensionless ultimate lateral capacity and dimensionless rotation center were the univariate functions of the embedded ratio. Also, the ultimate lateral capacity in the c- φ soil was the combination of the ultimate lateral capacity ( f c ) in the clay, and the ultimate lateral capacity ( f φ ) in the sand. Therefore, the Broms chart for clay, solution for clay ( φ=0) put forward by Poulos and Davis, solution for sand ( c=0) obtained by Petrasovits and Awad, and Kondner's ultimate bending moment were all proven to be the special cases of the general solution in the present study. A comparison of the field and laboratory tests in 93 cases showed that the average ratios of the theoretical values to the experimental value ranged from 0.85 to 1.15. Also, the theoretical values displayed a good agreement with the test values.
Homogenization models for thin rigid structured surfaces and films.
Marigo, Jean-Jacques; Maurel, Agnès
2016-07-01
A homogenization method for thin microstructured surfaces and films is presented. In both cases, sound hard materials are considered, associated with Neumann boundary conditions and the wave equation in the time domain is examined. For a structured surface, a boundary condition is obtained on an equivalent flat wall, which links the acoustic velocity to its normal and tangential derivatives (of the Myers type). For a structured film, jump conditions are obtained for the acoustic pressure and the normal velocity across an equivalent interface (of the Ventcels type). This interface homogenization is based on a matched asymptotic expansion technique, and differs slightly from the classical homogenization, which is known to fail for small structuration thicknesses. In order to get insight into what causes this failure, a two-step homogenization is proposed, mixing classical homogenization and matched asymptotic expansion. Results of the two homogenizations are analyzed in light of the associated elementary problems, which correspond to problems of fluid mechanics, namely, potential flows around rigid obstacles.
Thermally-Induced Structural Disturbances of Rigid Panel Solar Arrays
Johnston, John D.; Thornton, Earl A.
1997-01-01
The performance of a significant number of spacecraft has been impacted negatively by attitude disturbances resulting from thermally-induced motions of flexible structures. Recent examples of spacecraft affected by these disturbances include the Hubble Space Telescope (HST) and the Upper Atmosphere Research Satellite (UARS). Thermally-induced structural disturbances occur as the result of rapid changes in thermal loading typically initiated as a satellite exits or enters the Earth's shadow. Temperature differences in flexible appendages give rise to structural deformations, which in turn result in disturbance torques reacting back on the spacecraft. Structures which have proven susceptible to these disturbances include deployable booms and solar arrays. This paper investigates disturbances resulting from thermally-induced deformations of rigid panel solar arrays. An analytical model for the thermal-structural response of the solar array and the corresponding disturbance torque are presented. The effect of these disturbances on the attitude dynamics of a simple spacecraft is then investigated using a coupled system of governing equations which includes the effects of thermally-induced deformations. Numerical results demonstrate the effect of varying solar array geometry on the dynamic response of the system.
On removing interpolation and resampling artifacts in rigid image registration.
Aganj, Iman; Yeo, Boon Thye Thomas; Sabuncu, Mert R; Fischl, Bruce
2013-02-01
We show that image registration using conventional interpolation and summation approximations of continuous integrals can generally fail because of resampling artifacts. These artifacts negatively affect the accuracy of registration by producing local optima, altering the gradient, shifting the global optimum, and making rigid registration asymmetric. In this paper, after an extensive literature review, we demonstrate the causes of the artifacts by comparing inclusion and avoidance of resampling analytically. We show the sum-of-squared-differences cost function formulated as an integral to be more accurate compared with its traditional sum form in a simple case of image registration. We then discuss aliasing that occurs in rotation, which is due to the fact that an image represented in the Cartesian grid is sampled with different rates in different directions, and propose the use of oscillatory isotropic interpolation kernels, which allow better recovery of true global optima by overcoming this type of aliasing. Through our experiments on brain, fingerprint, and white noise images, we illustrate the superior performance of the integral registration cost function in both the Cartesian and spherical coordinates, and also validate the introduced radial interpolation kernel by demonstrating the improvement in registration.
Super rigid nature of super-deformed bands
International Nuclear Information System (INIS)
Sharma, Neha; Mittal, H.M.; Jain, A.K.
2012-01-01
The phenomenon of high-spin super-deformation represents one of the most remarkable discoveries in nuclear physics. A large number of SD bands have been observed in A = 60, 80, 130, 150, 190 mass regions. The cascades of SD bands are known to be connected by electric quadruple E2 transitions. Because of absence of linking transitions between superdeformed (SD) and normal deformed (ND) levels, the spin assignments of most of these bands carry a minimum uncertainty ≈ 1-2ħ. It was found in an analysis of SD bands in the context of semi classical approach that moment of inertia comes close to the rigid body value in most of the cases. Lack of knowledge of spins has led to an emphasis on the study of dynamical moment of inertia of SD bands and systematic of kinematic moment of inertia has not been examined so far. In this paper, we extract the band moment of inertia J 0 and softness parameter (σ) of all the SD bands corresponding to axes ratio (x) = 1.5 and present their systematic
Optical characterization and polarization calibration for rigid endoscopes
Garcia, Missael; Gruev, Viktor
2017-02-01
Polarization measurements give orthogonal information to spectral images making them a great tool in the characterization of environmental parameters in nature. Thus, polarization imagery has proven to be remarkably useful in a vast range of biomedical applications. One such application is the early diagnosis of flat cancerous lesions in murine colorectal tumor models, where polarization data complements NIR fluorescence analysis. Advances in nanotechnology have led to compact and precise bio-inspired imaging sensors capable of accurately co-registering multidimensional spectral and polarization information. As more applications emerge for these imagers, the optics used in these instruments get very complex and can potentially compromise the original polarization state of the incident light. Here we present a complete optical and polarization characterization of three rigid endoscopes of size 1.9mm x 10cm (Karl Storz, Germany), 5mm x 30cm, and 10mm x 33cm (Olympus, Germany), used in colonoscopy for the prevention of colitis-associated cancer. Characterization results show that the telescope optics act as retarders and effectively depolarize the linear component. These incorrect readings can cause false-positives or false-negatives leading to an improper diagnosis. In this paper, we offer a polarization calibration scheme for these endoscopes based on Mueller calculus. By modeling the optical properties from training data as real-valued Mueller matrices, we are able to successfully reconstruct the initial polarization state acquired by the imaging system.
Non-Invasive Ocular Rigidity Measurement: A Differential Tonometry Approach
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Efstathios T. Detorakis
2015-12-01
Full Text Available Purpose: Taking into account the fact that Goldmann applanation tonometry (GAT geometrically deforms the corneal apex and displaces volume from the anterior segment whereas Dynamic Contour Tonometry (DCT does not, we aimed at developing an algorithm for the calculation of ocular rigidity (OR based on the differences in pressure and volume between deformed and non-deformed status according to the general Friedenwald principle of differential tonometry. Methods: To avoid deviations of GAT IOP from true IOP in eyes with corneas different from the “calibration cornea” we applied the previously described Orssengo-Pye algorithm to calculate an error coefficient “C/B”. To test the feasibility of the proposed model, we calculated the OR coefficient (r in 17 cataract surgery candidates (9 males and 8 females. Results: The calculated r according to our model (mean ± SD, range was 0.0174 ± 0.010 (0.0123–0.022 mmHg/μL. A negative statistically significant correlation between axial length and r was detected whereas correlations between r and other biometric parameters examined were statistically not significant. Conclusions: The proposed method may prove a valid non-invasive tool for the measurement method of OR, which could help in introducing OR in the decision-making of the routine clinical practice.
Barber, F Alan
2013-09-01
To compare the load-to-failure pullout strength of bone-patellar tendon-bone (BPTB) allografts in human cadaver tibias and rigid polyurethane foam blocks. Twenty BPTB allografts were trimmed creating 25 mm × 10 mm × 10 mm tibial plugs. Ten-millimeter tunnels were drilled in 10 human cadaver tibias and 10 rigid polyurethane foam blocks. The BPTB anterior cruciate ligament allografts were inserted into these tunnels and secured with metal interference screws, with placement of 10 of each type in each material. After preloading (10 N), cyclic loading (500 cycles, 10 to 150 N at 200 mm/min) and load-to-failure testing (200 mm/min) were performed. The endpoints were ultimate failure load, cyclic loading elongation, and failure mode. No difference in ultimate failure load existed between grafts inserted into rigid polyurethane foam blocks (705 N) and those in cadaver tibias (669 N) (P = .69). The mean rigid polyurethane foam block elongation (0.211 mm) was less than that in tibial bone (0.470 mm) (P = .038), with a smaller standard deviation (0.07 mm for foam) than tibial bone (0.34 mm). All BPTB grafts successfully completed 500 cycles. The rigid polyurethane foam block showed less variation in test results than human cadaver tibias. Rigid polyurethane foam blocks provide an acceptable substitute for human cadaver bone tibia for biomechanical testing of BPTB allografts and offer near-equivalent results. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
H infinity controller design to a rigid-flexible satellite with two vibration modes
International Nuclear Information System (INIS)
De Souza, A G; De Souza, L C G
2015-01-01
The satellite attitude control system (ACS) design becomes more complex when the satellite structure has components like, flexible solar panels, antennas and mechanical manipulators. These flexible structures can interact with the satellite rigid parts during translational and/or rotational manoeuvre damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. This paper deals with the rigid-flexible satellite ACS design using the H infinity method. The rigid-flexible satellite is represented by a beam connected to a central rigid hub at one end and free at the other one. The equations of motions are obtained considering small flexible deformations and the Euler-Bernoulli hypothesis. The results of the simulations have shown that the H-infinity controller was able to control the rigid motion and suppress the vibrations. (paper)
A topological classification of the Chaplygin systems in the dynamics of a rigid body in a fluid
International Nuclear Information System (INIS)
Nikolaenko, S S
2014-01-01
The paper is concerned with the topological analysis of the Chaplygin integrable case in the dynamics of a rigid body in a fluid. A full list of the topological types of Chaplygin systems in their dependence on the energy level is compiled on the basis of the Fomenko-Zieschang theory. An effective description of the topology of the Liouville foliation in terms of natural coordinate variables is also presented, which opens a direct way to calculating topological invariants. It turns out that on all nonsingular energy levels Chaplygin systems are Liouville equivalent to the well-known Euler case in the dynamics of a rigid body with fixed point. Bibliography: 23 titles
C-map for Born-Infeld theories
Andrianopoli, Laura; Ferrara, Sergio; Trigiante, Mario
2016-01-01
The c-map of four dimensional non-linear theories of electromagnetism is considered both in the rigid case and in its coupling to gravity. In this way theories with antisymmetric tensors and scalars are obtained, and the three non-linear representations of N=2 supersymmetry partially broken to N=1 related. The manifest $\\mathrm{Sp}(2n)$ and $\\mathrm{U}(n)$ covariance of these theories in their multifield extensions is also exhibited.
Determination of Weight Suspension Rigidity in the Transport-Erector Aggregates
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V. A. Zverev
2016-01-01
Full Text Available The aim is to determine weight suspension rigidity in aggregates designed to perform technological transport-erector operations at the miscellaneous launch complexes.We consider the weight suspension comprising the following distinctive structural components: the executive weight-lowering mechanism, polyspast mechanism, rope, traverse, and rods. A created structural dynamic model of suspension allowed us to define weight suspension rigidity. Within the framework of design analysis of a dynamic model we determined the rigidity of its structural units, i.e. traverse, rope, and polyspast.Known analytical relationships were used to calculate the rope rigidity. To determine rigidity of polyspast and traverse have been created special models based on the finite element method. For each model deformation in the specific points under the test load have been defined. Data obtained were used to determine trigidity of traverses and polyspast, and also rigidity of suspension in total. The rigidity models of polispast mechanism and traverse have been developed and calculated using the software complex "Zenit-95".As the research results, the paper presents a dynamic model of the weight suspension of the transport-erector aggregate, the finite element models of the polispast mechanism and traverse, an algorithm for determining the weight suspension rigidity and relevant analytical relationships.Independent calculation of weight suspension rigidity enables us to simplify further dynamic calculation of the aggregate-weight system because it allows attaining a simpler model of the aggregate-weight system that uses the weight suspension model as an element of equivalent rigidity. Despite this simplification the model allows us to determine correctly weight movement parameters and overloads in the aggregate-weight system in the process of technical operations.
Puljiz, Mate; Menzel, Andreas M.
2017-05-01
Embedding rigid inclusions into elastic matrix materials is a procedure of high practical relevance, for instance, for the fabrication of elastic composite materials. We theoretically analyze the following situation. Rigid spherical inclusions are enclosed by a homogeneous elastic medium under stick boundary conditions. Forces and torques are directly imposed from outside onto the inclusions or are externally induced between them. The inclusions respond to these forces and torques by translations and rotations against the surrounding elastic matrix. This leads to elastic matrix deformations, and in turn results in mutual long-ranged matrix-mediated interactions between the inclusions. Adapting a well-known approach from low-Reynolds-number hydrodynamics, we explicitly calculate the displacements and rotations of the inclusions from the externally imposed or induced forces and torques. Analytical expressions are presented as a function of the inclusion configuration in terms of displaceability and rotateability matrices. The role of the elastic environment is implicitly included in these relations. That is, the resulting expressions allow a calculation of the induced displacements and rotations directly from the inclusion configuration, without having to explicitly determine the deformations of the elastic environment. In contrast to the hydrodynamic case, compressibility of the surrounding medium is readily taken into account. We present the complete derivation based on the underlying equations of linear elasticity theory. In the future, the method will, for example, be helpful to characterize the behavior of externally tunable elastic composite materials, to accelerate numerical approaches, as well as to improve the quantitative interpretation of microrheological results.
Superspace conformal field theory
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Quella, Thomas [Koeln Univ. (Germany). Inst. fuer Theoretische Physik; Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-07-15
Conformal sigma models and WZW models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type I supergroups, the classification of conformal sigma models and their embedding into string theory.
Superspace conformal field theory
International Nuclear Information System (INIS)
Quella, Thomas
2013-07-01
Conformal sigma models and WZW models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type I supergroups, the classification of conformal sigma models and their embedding into string theory.
Schmidt, Ulrich; Zank, Horst
2010-01-01
In previous models of (cumulative) prospect theory reference-dependence of preferences is imposed beforehand and the location of the reference point is exogenously determined. This paper provides an axiomatization of a new specification of cumulative prospect theory, termed endogenous prospect theory, where reference-dependence is derived from preference conditions and a unique reference point arises endogenously.
Directory of Open Access Journals (Sweden)
Vivian B. Martin, Ph.D.
2005-03-01
Full Text Available Bookshelf will provide critical reviews and perspectives on books on theory and methodology of interest to grounded theory. This issue includes a review of Heaton’s Reworking Qualitative Data, of special interest for some of its references to grounded theory as a secondary analysis tool; and Goulding’s Grounded Theory: A practical guide for management, business, and market researchers, a book that attempts to explicate the method and presents a grounded theory study that falls a little short of the mark of a fully elaborated theory.Reworking Qualitative Data, Janet Heaton (Sage, 2004. Paperback, 176 pages, $29.95. Hardcover also available.
Schürmann, Michael
2008-01-01
This volume contains the revised and completed notes of lectures given at the school "Quantum Potential Theory: Structure and Applications to Physics," held at the Alfried-Krupp-Wissenschaftskolleg in Greifswald from February 26 to March 10, 2007. Quantum potential theory studies noncommutative (or quantum) analogs of classical potential theory. These lectures provide an introduction to this theory, concentrating on probabilistic potential theory and it quantum analogs, i.e. quantum Markov processes and semigroups, quantum random walks, Dirichlet forms on C* and von Neumann algebras, and boundary theory. Applications to quantum physics, in particular the filtering problem in quantum optics, are also presented.
Vision based tunnel inspection using non-rigid registration
Badshah, Amir; Ullah, Shan; Shahzad, Danish
2015-04-01
Growing numbers of long tunnels across the globe has increased the need for safety measurements and inspections of tunnels in these days. To avoid serious damages, tunnel inspection is highly recommended at regular intervals of time to find any deformations or cracks at the right time. While following the stringent safety and tunnel accessibility standards, conventional geodetic surveying using techniques of civil engineering and other manual and mechanical methods are time consuming and results in troublesome of routine life. An automatic tunnel inspection by image processing techniques using non rigid registration has been proposed. There are many other image processing methods used for image registration purposes. Most of the processes are operation of images in its spatial domain like finding edges and corners by Harris edge detection method. These methods are quite time consuming and fail for some or other reasons like for blurred or images with noise. Due to use of image features directly by these methods in the process, are known by the group, correlation by image features. The other method is featureless correlation, in which the images are converted into its frequency domain and then correlated with each other. The shift in spatial domain is the same as in frequency domain, but the processing is order faster than in spatial domain. In the proposed method modified normalized phase correlation has been used to find any shift between two images. As pre pre-processing the tunnel images i.e. reference and template are divided into small patches. All these relative patches are registered by the proposed modified normalized phase correlation. By the application of the proposed algorithm we get the pixel movement of the images. And then these pixels shifts are converted to measuring units like mm, cm etc. After the complete process if there is any shift in the tunnel at described points are located.
Noise characteristics of barium ferrite particulate rigid disks
Kodama, Naoki; Inoue, Hitoshi; Spratt, Geoffrey; Uesaka, Yasutaro; Katsumoto, Masayuki
1991-04-01
This paper discusses the relationship between the noise characteristics and magnetic properties of longitudinal barium ferrite (Ba-F) rigid disks with different switching field distributions (SFD). The magnetomotive force dependencies of reverse dc-erase (RDC) noise are measured and compared with SFD values. Coated disks with acicular magnetic particles have dips and thin-film disks peaks in the RDC. In Ba-F disks, both cases are observed depending on the SFD values, though the depths or heights of the RDC noise are much smaller than those of coated disks with acicular particles or thin-film disks. Disks with small SFD values have peaks, and disks with large SFD values have dips. In order to find the relationship between noise properties and magnetic properties, interparticle interactions in Ba-F disks are investigated. Reverse dc remanence Id(H) and ac-demagnetized isothermal remanence Ir(H) are measured. Both are normalized by the saturation remanence. The deviation from the noninteracting system, ΔM = Id(H) - [1ΔM=Id(H)-[1- 2Ir(H)] and an interaction field factor (IFF) given by (H'r - Hr)/Hc, are derived from these remanent properties. Here, H'r is the field corresponding to 50% of the remanent magnetization, Hr is remanence coercivity. In Ba-F disks, ΔM shows positive interactions, and the peak heights of ΔM increase and IFF decrease with decreasing SFD values. Positive interactions between Ba-F particles seem to be caused by particle stacking. Therefore, particle stacking results in small SFD values and peak-type RDC noise.
Rigid Polyurethane Foam Thermal Insulation Protected with Mineral Intumescent Mat
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Kirpluks Mikelis
2014-12-01
Full Text Available One of the biggest disadvantages of rigid polyurethane (PU foams is its low thermal resistance, high flammability and high smoke production. Greatest advantage of this thermal insulation material is its low thermal conductivity (λ, which at 18-28 mW/(m•K is superior to other materials. To lower the flammability of PU foams, different flame retardants (FR are used. Usually, industrially viable are halogenated liquid FRs but recent trends in EU regulations show that they are not desirable any more. Main concern is toxicity of smoke and health hazard form volatiles in PU foam materials. Development of intumescent passive fire protection for foam materials would answer problems with flammability without using halogenated FRs. It is possible to add expandable graphite (EG into PU foam structure but this increases the thermal conductivity greatly. Thus, the main advantage of PU foam is lost. To decrease the flammability of PU foams, three different contents 3%; 9% and 15% of EG were added to PU foam formulation. Sample with 15% of EG increased λ of PU foam from 24.0 to 30.0 mW/(m•K. This paper describes the study where PU foam developed from renewable resources is protected with thermally expandable intumescent mat from Technical Fibre Products Ltd. (TFP as an alternative to EG added into PU material. TFP produces range of mineral fibre mats with EG that produce passive fire barrier. Two type mats were used to develop sandwich-type PU foams. Also, synergy effect of non-halogenated FR, dimethyl propyl phosphate and EG was studied. Flammability of developed materials was assessed using Cone Calorimeter equipment. Density, thermal conductivity, compression strength and modulus of elasticity were tested for developed PU foams. PU foam morphology was assessed from scanning electron microscopy images.
International Nuclear Information System (INIS)
Sabitov, I Kh
2013-01-01
The subject of this article is one of the most important questions of classical geometry: the theory of bendings and infinitesimal bendings of surfaces. These questions are studied for surfaces of revolution and, unlike previous well-known works, we make only minimal smoothness assumptions (the class C 1 ) in the initial part of our study. In this class we prove local existence and uniqueness theorems for infinitesimal bendings. We then consider the analytic class and establish simple criteria for rigidity and inflexibility of compact surfaces. These criteria depend on the values of certain integer characteristics related to the order of flattening of the surface at its poles. We also show that in the nonanalytic situation there exist nonrigid surfaces with any given order of flattening at the poles. Bibliography: 22 titles
Felderhof, B. U.
2015-11-01
A mechanical model of swimming and flying in an incompressible viscous fluid in the absence of gravity is studied on the basis of assumed equations of motion. The system is modeled as an assembly of rigid spheres subject to elastic direct interactions and to periodic actuating forces which sum to zero. Hydrodynamic interactions are taken into account in the virtual mass matrix and in the friction matrix of the assembly. An equation of motion is derived for the velocity of the geometric center of the assembly. The mean power is calculated as the mean rate of dissipation. The full range of viscosity is covered, so that the theory can be applied to the flying of birds, as well as to the swimming of fish or bacteria. As an example a system of three equal spheres moving along a common axis is studied.
International Nuclear Information System (INIS)
Krbalek, Milan; Hrabak, Pavel
2011-01-01
We consider the one-dimensional totally asymmetric simple exclusion process (TASEP model) with open boundary conditions and present the analytical computations leading to the exact formula for distance clearance distribution, i.e. probability density for a clear distance between subsequent particles of the model. The general relation is rapidly simplified for the middle part of the one-dimensional lattice. Both the analytical formulas and their approximations are compared with the numerical representation of the TASEP model. Such a comparison is presented for particles occurring in the internal part as well as in the boundary part of the lattice. Furthermore, we introduce the pertinent estimation for the so-called spectral rigidity of the model. The results obtained are sequentially discussed within the scope of vehicular traffic theory.
International Nuclear Information System (INIS)
Alania, M V; Wawrzynczak, A; Sdobnov, V E; Kravtsova, M V
2013-01-01
Forbush decreases (Fd) of the galactic cosmic ray (GCR) intensity and geomagnetic storms are observed almost at the same time. Geomagnetic storm is a reason of significant disturbances of the magnetic cut off rigidity causing the distortion of the time profile of the Fd of the GCR intensity. We show some differences in the temporal changes of the rigidity spectra of Fd calculated by neutron monitors experimental data corrected and uncorrected for the changes of the geomagnetic cut off rigidity. Nevertheless, the general features of the temporal changes of the rigidity spectrum of Fd maintain as it was found in our previous investigations. Namely, at the beginning phase of Fd rigidity spectrum is relatively soft and gradually becomes hard up to reaching the minimum level of the GCR intensity; then the rigidity spectrum gradually becomes soft during the recovery phase of Fd. We also confirm that for the established temporal profiles of the rigidity spectrum of Fd a structural changes of the interplanetary magnetic field turbulence in the range of frequencies, 10 −-6 ÷10 −-5 Hz are responsible.
Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V
2013-09-05
Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.
Connections rigidity effect on probability of fracture in steel moment frames
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Gholamreza Abdollahzadeh
2017-08-01
Full Text Available Connections in steel moment frames are idealized in full pinned and full rigid conditions. Because with this assumption, in spite of real behavior of connection, real story drifts are less anticipated and maybe frame is designed without performance of bracing. There are several methods for modeling actual behavior of semi rigid connections. In this method a connection with certain rigidity is modeled by a rotational spring with corresponding stiffness. This stiffness is achieved by certain formula. In other words, each percent of rigidity corresponds to one rotational spring stiffness. In this research in order to evaluate the real behavior of connection in analysis and designing process and fracture probability one frame including four stories and one bay with three types of connection has been modeled and designed in ETABS. Each model has an individual rigidity which is equal to 10, 75 and 90 percent. With respect to maximum drift and different PGA in roof, probabilities of low, medium, high and complete fracture were calculated. For this purpose, with applying different PGA to modeled frames, amounts of drift in the roof are achieved. Then these values are compared with given values in American code. Finally, investigation showed that when rigidity in frame connections increases, the probability of frame fracture decreases. In other words, fully rigid assumption of connection in analysis process leads to decreasing in real probability of fracture in frames which is a noticeable risk in building designing processes.
A rigidity transition and glassy dynamics in a model for confluent 3D tissues
Merkel, Matthias; Manning, M. Lisa
The origin of rigidity in disordered materials is an outstanding open problem in statistical physics. Recently, a new type of rigidity transition was discovered in a family of models for 2D biological tissues, but the mechanisms responsible for rigidity remain unclear. This is not just a statistical physics problem, but also relevant for embryonic development, cancer growth, and wound healing. To gain insight into this rigidity transition and make new predictions about biological bulk tissues, we have developed a fully 3D self-propelled Voronoi (SPV) model. The model takes into account shape, elasticity, and self-propelled motion of the individual cells. We find that in the absence of self-propulsion, this model exhibits a rigidity transition that is controlled by a dimensionless model parameter describing the preferred cell shape, with an accompanying structural order parameter. In the presence of self-propulsion, the rigidity transition appears as a glass-like transition featuring caging and aging effects. Given the similarities between this transition and jamming in particulate solids, it is natural to ask if the two transitions are related. By comparing statistics of Voronoi geometries, we show the transitions are surprisingly close but demonstrably distinct. Furthermore, an index theorem used to identify topologically protected mechanical modes in jammed systems can be extended to these vertex-type models. In our model, residual stresses govern the transition and enter the index theorem in a different way compared to jammed particles, suggesting the origin of rigidity may be different between the two.
Regulation of Breast Cancer Stem Cell by Tissue Rigidity
2014-06-01
metastasis. Cancer Cell 20: 576– 590 . Ledford H. 2011. Cancer theory faces doubts. Nature 472: 273. Lee KE, Bar-Sagi D. 2010. Oncogenic KRas suppresses...blocks the cell cycle and confers resistance to cell death. Genes Dev 18: 1131–1143. Vesuna F, Lisok A, Kimble B, Raman V. 2009. Twist modulates
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Eduardo Franzotti Sant'Anna
2013-08-01
Full Text Available INTRODUCTION: Distraction Osteogenesis (DO became an alternative for the treatment of severe craniofacial skeletal dysplasias. The rigid external distraction device (RED is successfully used to advance the maxilla and all the maxillary-orbital-frontal complex (monobloc in children, adolescents and adults. This approach provides predictable and stable results, and it can be applied alone or with craniofacial orthognathic surgical procedures. OBJECTIVE: In the present article, the technical aspects relevant to an adequate application of the RED will be described, including the planning, surgical and orthodontic procedures.
DEFF Research Database (Denmark)
Wæver, Ole
2009-01-01
-empiricism and anti-positivism of his position. Followers and critics alike have treated Waltzian neorealism as if it was at bottom a formal proposition about cause-effect relations. The extreme case of Waltz being so victorious in the discipline, and yet being consistently mis-interpreted on the question of theory......, shows the power of a dominant philosophy of science in US IR, and thus the challenge facing any ambitious theorising. The article suggests a possible movement of fronts away from the ‘fourth debate' between rationalism and reflectivism towards one of theory against empiricism. To help this new agenda...
High frequency permeameter with semi-rigid pick-up coil
International Nuclear Information System (INIS)
Shin, Sung-Yong; Shin, Kwang-Ho . E-mail : khshin@star.ks.ac.kr; Kim, Jong-sung; Kim, Young-Hak; Lim, Sang-Ho; Sa-gong, Geon
2006-01-01
In this study, we propose the application of semi-rigid cable loop as a single turn shielded loop pick-up coil for the high frequency permeameter. Since the semi-rigid cable pick-up coil has simple structure, it is very easy to make the pick-up coil with bending and conventional soldering. The permeability of cobalt base amorphous ribbon was investigated using the developed permeameter for demonstrating its performance. The permeability of the amorphous ribbon was driven from the S-parameters measured using a network analyzer and permameter having the semi-rigid pick-up coil
Wobbling motion: A γ-rigid or γ-soft mode?
International Nuclear Information System (INIS)
Casten, R.F.; McCutchan, E.A.; Beausang, C.W.; Zamfir, N.V.; Zhang Jingye
2003-01-01
For even-even nuclei, it is shown that the predicted B(E2) values from the odd spin states of the quasi-γ band in a γ-soft nucleus to the yrast band are quite similar to those predicted for the one-phonon wobbling mode of a rigidly triaxial nucleus. This suggests that the observation of wobbling points to axial asymmetry, but not necessarily to rigid triaxiality. However, another observable that does distinguish γ-soft from γ-rigid structure is identified
Energy Technology Data Exchange (ETDEWEB)
Jung, Hannes; /DESY; De Roeck, Albert; /CERN; Bartels, Jochen; /Hamburg U., Inst. Theor. Phys. II; Behnke, Olaf; Blumlein, Johannes; /DESY; Brodsky, Stanley; /SLAC /Durham U., IPPP; Cooper-Sarkar, Amanda; /Oxford U.; Deak, Michal; /DESY; Devenish, Robin; /Oxford U.; Diehl, Markus; /DESY; Gehrmann, Thomas; /Zurich U.; Grindhammer, Guenter; /Munich, Max Planck Inst.; Gustafson, Gosta; /CERN /Lund U., Dept. Theor. Phys.; Khoze, Valery; /Durham U., IPPP; Knutsson, Albert; /DESY; Klein, Max; /Liverpool U.; Krauss, Frank; /Durham U., IPPP; Kutak, Krzysztof; /DESY; Laenen, Eric; /NIKHEF, Amsterdam; Lonnblad, Leif; /Lund U., Dept. Theor. Phys.; Motyka, Leszek; /Hamburg U., Inst. Theor. Phys. II /Birmingham U. /Southern Methodist U. /DESY /Piemonte Orientale U., Novara /CERN /Paris, LPTHE /Hamburg U. /Penn State U.
2011-11-10
More than 100 people participated in a discussion session at the DIS08 workshop on the topic What HERA may provide. A summary of the discussion with a structured outlook and list of desirable measurements and theory calculations is given. The HERA accelerator and the HERA experiments H1, HERMES and ZEUS stopped running in the end of June 2007. This was after 15 years of very successful operation since the first collisions in 1992. A total luminosity of {approx} 500 pb{sup -1} has been accumulated by each of the collider experiments H1 and ZEUS. During the years the increasingly better understood and upgraded detectors and HERA accelerator have contributed significantly to this success. The physics program remains in full swing and plenty of new results were presented at DIS08 which are approaching the anticipated final precision, fulfilling and exceeding the physics plans and the previsions of the upgrade program. Most of the analyses presented at DIS08 were still based on the so called HERA I data sample, i.e. data taken until 2000, before the shutdown for the luminosity upgrade. This sample has an integrated luminosity of {approx} 100 pb{sup -1}, and the four times larger statistics sample from HERA II is still in the process of being analyzed.
Directory of Open Access Journals (Sweden)
Kate Zoellner
2010-06-01
practical dimensions of life” (p. 445; information relevant to lower working class individuals is that which “solve[s] problematic situations” (p. 441. Study participants’ social conversations revolved around events that reinforced their mental models. Respondents relied on themselves and distrusted those outside their social circles.6. Use of the Mass Media. Mass media is perceived as a vehicle for passing time, escape, and entertainment, as well as a reflection of lived realities for the population. Respondents indicated that they watched television to pass time, and, secondarily, for practical purposes (e.g., learning how to be safe.Conclusion – Gratification theory provides a useful framework for library and information professionals to identify how populations define information problems and reliable sources, and their information seeking behaviours and motivations. Chatman’s analysis indicates that the everyday problems faced by the lower working class are not, and will not be, met by traditional sources that information professionals assume to be of value for the population. Based on these research results, Chatman calls on information professionals to critically evaluate and broaden their understanding of how problems are defined and addressed by the specific populations they seek to serve – to consider the relationships between the pressing realities of their service populations and everyday information that addresses those realities. This understanding will enable information professionals to determine if, how, and by what means, they should develop and package information to meet the needs of their service populations and communities.
Aguilar, M.; Ali Cavasonza, L.; Alpat, B.; Ambrosi, G.; Arruda, L.; Attig, N.; Aupetit, S.; Azzarello, P.; Bachlechner, A.; Barao, F.; Barrau, A.; Barrin, L.; Bartoloni, A.; Basara, L.; Başeǧmez-du Pree, S.; Battarbee, M.; Battiston, R.; Becker, U.; Behlmann, M.; Beischer, B.; Berdugo, J.; Bertucci, B.; Bindel, K. F.; Bindi, V.; de Boer, W.; Bollweg, K.; Bonnivard, V.; Borgia, B.; Boschini, M. J.; Bourquin, M.; Bueno, E. F.; Burger, J.; Burger, W. J.; Cadoux, F.; Cai, X. D.; Capell, M.; Caroff, S.; Casaus, J.; Castellini, G.; Cervelli, F.; Chae, M. J.; Chang, Y. H.; Chen, A. I.; Chen, G. M.; Chen, H. S.; Cheng, L.; Chou, H. Y.; Choumilov, E.; Choutko, V.; Chung, C. H.; Clark, C.; Clavero, R.; Coignet, G.; Consolandi, C.; Contin, A.; Corti, C.; Creus, W.; Crispoltoni, M.; Cui, Z.; Dadzie, K.; Dai, Y. M.; Datta, A.; Delgado, C.; Della Torre, S.; Demakov, O.; Demirköz, M. B.; Derome, L.; Di Falco, S.; Dimiccoli, F.; Díaz, C.; von Doetinchem, P.; Dong, F.; Donnini, F.; Duranti, M.; D'Urso, D.; Egorov, A.; Eline, A.; Eronen, T.; Feng, J.; Fiandrini, E.; Fisher, P.; Formato, V.; Galaktionov, Y.; Gallucci, G.; García-López, R. J.; Gargiulo, C.; Gast, H.; Gebauer, I.; Gervasi, M.; Ghelfi, A.; Giovacchini, F.; Gómez-Coral, D. M.; Gong, J.; Goy, C.; Grabski, V.; Grandi, D.; Graziani, M.; Guo, K. H.; Haino, S.; Han, K. C.; He, Z. H.; Heil, M.; Hoffman, J.; Hsieh, T. H.; Huang, H.; Huang, Z. C.; Huh, C.; Incagli, M.; Ionica, M.; Jang, W. Y.; Jia, Yi; Jinchi, H.; Kang, S. C.; Kanishev, K.; Khiali, B.; Kim, G. N.; Kim, K. S.; Kirn, Th.; Konak, C.; Kounina, O.; Kounine, A.; Koutsenko, V.; Kulemzin, A.; La Vacca, G.; Laudi, E.; Laurenti, G.; Lazzizzera, I.; Lebedev, A.; Lee, H. T.; Lee, S. C.; Leluc, C.; Li, H. S.; Li, J. Q.; Li, Q.; Li, T. X.; Li, Y.; Li, Z. H.; Li, Z. Y.; Lim, S.; Lin, C. H.; Lipari, P.; Lippert, T.; Liu, D.; Liu, Hu; Lordello, V. D.; Lu, S. Q.; Lu, Y. S.; Luebelsmeyer, K.; Luo, F.; Luo, J. Z.; Lyu, S. S.; Machate, F.; Mañá, C.; Marín, J.; Martin, T.; Martínez, G.; Masi, N.; Maurin, D.; Menchaca-Rocha, A.; Meng, Q.; Mikuni, V. M.; Mo, D. C.; Mott, P.; Nelson, T.; Ni, J. Q.; Nikonov, N.; Nozzoli, F.; Oliva, A.; Orcinha, M.; Palmonari, F.; Palomares, C.; Paniccia, M.; Pauluzzi, M.; Pensotti, S.; Perrina, C.; Phan, H. D.; Picot-Clemente, N.; Pilo, F.; Pizzolotto, C.; Plyaskin, V.; Pohl, M.; Poireau, V.; Quadrani, L.; Qi, X. M.; Qin, X.; Qu, Z. Y.; Räihä, T.; Rancoita, P. G.; Rapin, D.; Ricol, J. S.; Rosier-Lees, S.; Rozhkov, A.; Rozza, D.; Sagdeev, R.; Schael, S.; Schmidt, S. M.; Schulz von Dratzig, A.; Schwering, G.; Seo, E. S.; Shan, B. S.; Shi, J. Y.; Siedenburg, T.; Son, D.; Song, J. W.; Tacconi, M.; Tang, X. W.; Tang, Z. C.; Tescaro, D.; Ting, Samuel C. C.; Ting, S. M.; Tomassetti, N.; Torsti, J.; Türkoǧlu, C.; Urban, T.; Vagelli, V.; Valente, E.; Valtonen, E.; Vázquez Acosta, M.; Vecchi, M.; Velasco, M.; Vialle, J. P.; Vitale, V.; Vitillo, S.; Wang, L. Q.; Wang, N. H.; Wang, Q. L.; Wang, X.; Wang, X. Q.; Wang, Z. X.; Wei, C. C.; Weng, Z. L.; Whitman, K.; Wu, H.; Wu, X.; Xiong, R. Q.; Xu, W.; Yan, Q.; Yang, J.; Yang, M.; Yang, Y.; Yi, H.; Yu, Y. J.; Yu, Z. Q.; Zannoni, M.; Zeissler, S.; Zhang, C.; Zhang, F.; Zhang, J.; Zhang, J. H.; Zhang, S. W.; Zhang, Z.; Zheng, Z. M.; Zhuang, H. L.; Zhukov, V.; Zichichi, A.; Zimmermann, N.; Zuccon, P.; AMS Collaboration
2017-12-01
We report the observation of new properties of primary cosmic rays He, C, and O measured in the rigidity (momentum/charge) range 2 GV to 3 TV with 90 ×106 helium, 8.4 ×106 carbon, and 7.0 ×106 oxygen nuclei collected by the Alpha Magnetic Spectrometer (AMS) during the first five years of operation. Above 60 GV, these three spectra have identical rigidity dependence. They all deviate from a single power law above 200 GV and harden in an identical way.
Fatoye, Francis; Haigh, Carol
2016-05-01
To examine the cost-effectiveness of semi-rigid ankle brace to facilitate return to work following first-time acute ankle sprains. Economic evaluation based on cost-utility analysis. Ankle sprains are a source of morbidity and absenteeism from work, accounting for 15-20% of all sports injuries. Semi-rigid ankle brace and taping are functional treatment interventions used by Musculoskeletal Physiotherapists and Nurses to facilitate return to work following acute ankle sprains. A decision model analysis, based on cost-utility analysis from the perspective of National Health Service was used. The primary outcomes measure was incremental cost-effectiveness ratio, based on quality-adjusted life years. Costs and quality of life data were derived from published literature, while model clinical probabilities were sourced from Musculoskeletal Physiotherapists. The cost and quality adjusted life years gained using semi-rigid ankle brace was £184 and 0.72 respectively. However, the cost and quality adjusted life years gained following taping was £155 and 0.61 respectively. The incremental cost-effectiveness ratio for the semi-rigid brace was £263 per quality adjusted life year. Probabilistic sensitivity analysis showed that ankle brace provided the highest net-benefit, hence the preferred option. Taping is a cheaper intervention compared with ankle brace to facilitate return to work following first-time ankle sprains. However, the incremental cost-effectiveness ratio observed for ankle brace was less than the National Institute for Health and Care Excellence threshold and the intervention had a higher net-benefit, suggesting that it is a cost-effective intervention. Decision-makers may be willing to pay £263 for an additional gain in quality adjusted life year. The findings of this economic evaluation provide justification for the use of semi-rigid ankle brace by Musculoskeletal Physiotherapists and Nurses to facilitate return to work in individuals with first-time ankle
Rigid Basement and the Evolution of the Pakistani Convergent Margin
Haq, S. S.; Davis, D. M.
2007-12-01
In Pakistan, along the western edge of the Indian-Eurasian collision there are a series of fold-and-thrust belts that have highly variable strikes and shortening directions with respect to the local relative plate motion. Much of the complexity in the deformation of this margin can easily be explained by the shape, location, and long-term motion of a fragment of relatively rigid oceanic lithosphere that is believed to underlie the Katawaz Basin. In particular, the deformation that has formed the Sulaiman Range and Lobe is a direct consequence of the Katawaz Basin's over all higher strength. The presence of deformed sedimentary strata in the basin comparable to those presently found in the Indus delta are indicative of the basins long-term motion parallel to the Chaman fault zone. In Pakistan, the transition in the strike and shortening directions occurs over a short distance compared to the width of the fold-belts and the length of the margin. We present a series of analog models along with detailed quantitative analysis that we compare to the observed deformation as indicated by both geologic and geophysical data. By quantitatively distinguishing the style and magnitude of deformation in each of a variety of analog experiments we are able to evaluate the viability of various alternative models that have been proposed for fold- belt formation and evolution of the Pakistani margin, including our favored model. The model that best fits the geological and geophysical evidence suggests that the complexity of the Pakistani margin is a result of the long- term northeastward migration of the Katawaz basin along the curving trend of the Chaman fault zone. The vertically integrated mechanical strength of the Katawaz basin allows it to act as a strong 'backstop' that has relative motion to both stable India and stable Eurasia. This northeastward motion and the resulting clockwise rotation of the Katawaz 'block' during the margin's development can explain the location and
A sequence-dependent rigid-base model of DNA
Gonzalez, O.; Petkevičiutė, D.; Maddocks, J. H.
2013-02-01
A novel hierarchy of coarse-grain, sequence-dependent, rigid-base models of B-form DNA in solution is introduced. The hierarchy depends on both the assumed range of energetic couplings, and the extent of sequence dependence of the model parameters. A significant feature of the models is that they exhibit the phenomenon of frustration: each base cannot simultaneously minimize the energy of all of its interactions. As a consequence, an arbitrary DNA oligomer has an intrinsic or pre-existing stress, with the level of this frustration dependent on the particular sequence of the oligomer. Attention is focussed on the particular model in the hierarchy that has nearest-neighbor interactions and dimer sequence dependence of the model parameters. For a Gaussian version of this model, a complete coarse-grain parameter set is estimated. The parameterized model allows, for an oligomer of arbitrary length and sequence, a simple and explicit construction of an approximation to the configuration-space equilibrium probability density function for the oligomer in solution. The training set leading to the coarse-grain parameter set is itself extracted from a recent and extensive database of a large number of independent, atomic-resolution molecular dynamics (MD) simulations of short DNA oligomers immersed in explicit solvent. The Kullback-Leibler divergence between probability density functions is used to make several quantitative assessments of our nearest-neighbor, dimer-dependent model, which is compared against others in the hierarchy to assess various assumptions pertaining both to the locality of the energetic couplings and to the level of sequence dependence of its parameters. It is also compared directly against all-atom MD simulation to assess its predictive capabilities. The results show that the nearest-neighbor, dimer-dependent model can successfully resolve sequence effects both within and between oligomers. For example, due to the presence of frustration, the model can
A sequence-dependent rigid-base model of DNA.
Gonzalez, O; Petkevičiūtė, D; Maddocks, J H
2013-02-07
A novel hierarchy of coarse-grain, sequence-dependent, rigid-base models of B-form DNA in solution is introduced. The hierarchy depends on both the assumed range of energetic couplings, and the extent of sequence dependence of the model parameters. A significant feature of the models is that they exhibit the phenomenon of frustration: each base cannot simultaneously minimize the energy of all of its interactions. As a consequence, an arbitrary DNA oligomer has an intrinsic or pre-existing stress, with the level of this frustration dependent on the particular sequence of the oligomer. Attention is focussed on the particular model in the hierarchy that has nearest-neighbor interactions and dimer sequence dependence of the model parameters. For a Gaussian version of this model, a complete coarse-grain parameter set is estimated. The parameterized model allows, for an oligomer of arbitrary length and sequence, a simple and explicit construction of an approximation to the configuration-space equilibrium probability density function for the oligomer in solution. The training set leading to the coarse-grain parameter set is itself extracted from a recent and extensive database of a large number of independent, atomic-resolution molecular dynamics (MD) simulations of short DNA oligomers immersed in explicit solvent. The Kullback-Leibler divergence between probability density functions is used to make several quantitative assessments of our nearest-neighbor, dimer-dependent model, which is compared against others in the hierarchy to assess various assumptions pertaining both to the locality of the energetic couplings and to the level of sequence dependence of its parameters. It is also compared directly against all-atom MD simulation to assess its predictive capabilities. The results show that the nearest-neighbor, dimer-dependent model can successfully resolve sequence effects both within and between oligomers. For example, due to the presence of frustration, the model can
DEFF Research Database (Denmark)
Clemmensen, Torkil; Kaptelinin, Victor; Nardi, Bonnie
2016-01-01
different ways of using activity theory: (1) analysing unique features, principles, and problematic aspects of the theory; (2) identifying domain-specific requirements for new theoretical tools; (3) developing new conceptual accounts of issues in the field of HCI; (4) guiding and supporting empirical...... analyses of HCI phenomena; and (5) providing new design illustrations, claims, and guidelines. We conclude that HCI researchers are not only users of imported theory, but also theory-makers who adapt and develop theory for different purposes.......This paper reports a study of the use of activity theory in human–computer interaction (HCI) research. We analyse activity theory in HCI since its first appearance about 25 years ago. Through an analysis and meta-synthesis of 109 selected HCI activity theory papers, we created a taxonomy of 5...
An investigation on the noise reduction performance of profiled rigid median barriers at highways
Directory of Open Access Journals (Sweden)
Mohammad Reza Monazzam
2012-01-01
Full Text Available Median barriers as a portion of a divided highway are provided to minimize the cross-median crashes. Moreover, median barriers similar to roadside noise barriers could protect people from transportation noise. Thus, there is a need to investigate various median barrier models to identify changes of insertion loss over a simple rigid barrier. In order to estimate the acoustical influence of median barrier′s profile in the shadow zone, different median barrier models are presented and their insertion losses are calculated over a frequency range from 50 to 4000 Hz using a two-dimensional boundary element method. The present investigation has clearly revealed that among the profiled median barriers, T-shape, Y-shape, and L-shape provide better performance than that of the other shapes. It is also found that among inclined barriers, V-shape barrier significantly presents higher values of attenuation. Based on the calculation of different geometrics, it has been shown that a further 2 dB (A in efficiency could be obtained by a better design of the median barrier which is labeled model "L."
Directory of Open Access Journals (Sweden)
Leandro Martínez
Full Text Available The analysis of structural mobility in molecular dynamics plays a key role in data interpretation, particularly in the simulation of biomolecules. The most common mobility measures computed from simulations are the Root Mean Square Deviation (RMSD and Root Mean Square Fluctuations (RMSF of the structures. These are computed after the alignment of atomic coordinates in each trajectory step to a reference structure. This rigid-body alignment is not robust, in the sense that if a small portion of the structure is highly mobile, the RMSD and RMSF increase for all atoms, resulting possibly in poor quantification of the structural fluctuations and, often, to overlooking important fluctuations associated to biological function. The motivation of this work is to provide a robust measure of structural mobility that is practical, and easy to interpret. We propose a Low-Order-Value-Optimization (LOVO strategy for the robust alignment of the least mobile substructures in a simulation. These substructures are automatically identified by the method. The algorithm consists of the iterative superposition of the fraction of structure displaying the smallest displacements. Therefore, the least mobile substructures are identified, providing a clearer picture of the overall structural fluctuations. Examples are given to illustrate the interpretative advantages of this strategy. The software for performing the alignments was named MDLovoFit and it is available as free-software at: http://leandro.iqm.unicamp.br/mdlovofit.
Aoun, Bachir
2016-05-05
A new Reverse Monte Carlo (RMC) package "fullrmc" for atomic or rigid body and molecular, amorphous, or crystalline materials is presented. fullrmc main purpose is to provide a fully modular, fast and flexible software, thoroughly documented, complex molecules enabled, written in a modern programming language (python, cython, C and C++ when performance is needed) and complying to modern programming practices. fullrmc approach in solving an atomic or molecular structure is different from existing RMC algorithms and software. In a nutshell, traditional RMC methods and software randomly adjust atom positions until the whole system has the greatest consistency with a set of experimental data. In contrast, fullrmc applies smart moves endorsed with reinforcement machine learning to groups of atoms. While fullrmc allows running traditional RMC modeling, the uniqueness of this approach resides in its ability to customize grouping atoms in any convenient way with no additional programming efforts and to apply smart and more physically meaningful moves to the defined groups of atoms. In addition, fullrmc provides a unique way with almost no additional computational cost to recur a group's selection, allowing the system to go out of local minimas by refining a group's position or exploring through and beyond not allowed positions and energy barriers the unrestricted three dimensional space around a group. © 2016 Wiley Periodicals, Inc.
A New and Versatile Adjustable Rigidity Actuator with Add-on Locking Mechanism (ARES-XL
Directory of Open Access Journals (Sweden)
Manuel Cestari
2018-01-01
Full Text Available Adjustable compliant actuators are being designed and implemented in robotic devices because of their ability to minimize large forces due to impacts, to safely interact with the user, and to store and release energy in passive elastic elements. Conceived as a new force-controlled compliant actuator, an adjustable rigidity with embedded sensor and locking mechanism actuator (ARES-XL is presented in this paper. This compliant system is intended to be implemented in a gait exoskeleton for children with neuro muscular diseases (NMDs to exploit the intrinsic dynamics during locomotion. This paper describes the mechanics and initial evaluation of the ARES-XL, a novel variable impedance actuator (VIA that allows the implementation of an add-on locking mechanism to this system, and in combination with its zero stiffness capability and large deflection range, provides this novel joint with improved properties when compared to previous prototypes developed by the authors and other state-of-the-art (SoA devices. The evaluation of the system proves how this design exceeds the main capabilities of a previous prototype as well as providing versatile actuation that could lead to its implementation in multiple joints.
Doppler ultrasound compatible plastic material for use in rigid flow models.
Wong, Emily Y; Thorne, Meghan L; Nikolov, Hristo N; Poepping, Tamie L; Holdsworth, David W
2008-11-01
A technique for the rapid but accurate fabrication of multiple flow phantoms with variations in vascular geometry would be desirable in the investigation of carotid atherosclerosis. This study demonstrates the feasibility and efficacy of implementing numerically controlled direct-machining of vascular geometries into Doppler ultrasound (DUS)-compatible plastic for the easy fabrication of DUS flow phantoms. Candidate plastics were tested for longitudinal speed of sound (SoS) and acoustic attenuation at the diagnostic frequency of 5 MHz. Teflon was found to have the most appropriate SoS (1376 +/- 40 m s(-1) compared with 1540 m s(-1) in soft tissue) and thus was selected to construct a carotid bifurcation flow model with moderate eccentric stenosis. The vessel geometry was machined directly into Teflon using a numerically controlled milling technique. Geometric accuracy of the phantom lumen was verified using nondestructive micro-computed tomography. Although Teflon displayed a higher attenuation coefficient than other tested materials, Doppler data acquired in the Teflon flow model indicated that sufficient signal power was delivered throughout the depth of the vessel and provided comparable velocity profiles to that obtained in the tissue-mimicking phantom. Our results indicate that Teflon provides the best combination of machinability and DUS compatibility, making it an appropriate choice for the fabrication of rigid DUS flow models using a direct-machining method.
High temperature testing of TRUPACT-I materials: Kevlar, honeycomb, rigid polyurethane foam
International Nuclear Information System (INIS)
Hudson, M.L.
1985-12-01
When the Transuranic Package Transporter Model-I (TRUPACT-I) failed to afford sufficient containment after a 35-minute JP-4 fueled open-pool fire, component tests were conducted, in conjunction with analyses, to guide and assess the redesign of TRUPACT-I. Since materials which change phase or combust are difficult to numerically analyze, the component tests determined the behavior of these materials in TRUPACT-I. The component tests approximated the behavior of Kevlar (registered trademark of DuPont), metal honeycomb, and rigid polyurethane foam, as they appear in TRUPACT-I, in an open-pool fire environment. Six series of tests were performed at Sandia's Radiant Heat Facility and one test at the wind-shielded fire test facility (LAARC Chimney). Each test facility was controlled to yield temperatures or heat fluxes equivalent to those measured in the TRUPACT-I, Unit 0, open-pool fire. This extensive series of component tests (34 runs total) provided information on the high-temperature behavior of unique materials which was not previously available or otherwise attainable. The component tests were a timely and cost-effective means of providing the data for the TRUPACT-I redesign
Energy Technology Data Exchange (ETDEWEB)
Sanz-Estebanez, S.; Royuela-del-Val, J.; Sevilla, T.; Revilla-Orodea, A.; Aja-Fernandez, S.; Alberola-Lopez, C.
2016-07-01
In this paper we present a new approach for non rigid groupwise registration of cardiac magnetic resonance images by means of free-form deformations, imposing a prior harmonic deformation assumption. The procedure proposes a primal-dual framework for solving an equality constrained minimization problem, which allows an automatic estimate of the trade-off between image fidelity and the Laplacian smoothness terms for each iteration. The method has been applied to both a 4D extended cardio-torso phantom and to a set of voluntary patients. The accuracy of the method has been measured for the synthetic experiment as the difference in modulus between the estimated displacement field and the ground truth; as for the real data, we have calculated the Dice coefficient between the contour manual delineations provided by two cardiologists at end systolic phase and those provided by them at end diastolic phase and, consequently propagated by the registration algorithm to the systolic instant. The automatic procedure turns out to be competitive in motion compensation with other methods even though their parameters have been previously set for optimal performance in different scenarios. (Author)
Frontal Tasks and Behavior in Rigid or Tremor-Dominant Parkinson Disease.
Moretti, Rita; Milner, Vera; Caruso, Paola; Gazzin, Silvia; Rumiati, Raffaella
2017-08-01
Parkinson disease (PD) is not an unambiguous entity, and there is a general consensus for the statement that an akinetic-rigid dominant type of presentation has a worse prognosis, in the follow-up. The aim of our study was to examine the differences in frontal tasks and behavior, in 2 PD naive groups: the rigid and the tremor-dominant types of presentation, according to motor scores. Our study has showed some important differences in frontal tasks and in behavior, performing more apathy, aggressiveness, and irritability in the rigid type, and more depression and anxiety in the tremor-dominant type. The former group causes the caregiver more distress and has a very rapid disease progression. It can be argued that rigid type PD presentation needs specific dedicated cares and more strong clinical attention.
National Research Council Canada - National Science Library
Greer, James
2002-01-01
This dissertation presents a systematic design methodology for directed product evolution that uses both rigid body and compliant mechanisms to facilitate component combination in the domain of mechanical products...
Frictionless contact of a rigid punch indenting a transversely isotropic elastic layer
Directory of Open Access Journals (Sweden)
Rajesh Patra
2016-03-01
Full Text Available This article is concerned with the study of frictionless contact between a rigid punch and a transversely isotropic elastic layer. The rigid punch is assumed to be axially symmetric and is being pressed towards the layer by an applied concentrated load. The layer is resting on a rigid base and is assumed to be ufficiently thick in comparison with the amount of indentation by the rigid punch. The relationship between the applied load $P$ and the contact area is obtained by solving the mathematically formulated problem through use of Hankel transform of different order. Effect of indentation on the distribution of normal stress at the surface as well as the relationship between the applied load and the area of contact have been shown graphically.
Fiber Optic Systems for Light Curing Rigidization of Inflatable Structures, Phase I
National Aeronautics and Space Administration — Light (UV and visible) curing composite matrix resins are being explored as an attractive means for rigidizing inflatable spacecraft for large space-deployed...
Market structure, price rigidity, and performance in the Indonesian food and beverages industry
Setiawan, M.
2012-01-01
Keywords: industrial concentration, price rigidity, technical efficiency, price-cost margin, Structure-Conduct-Performance (SCP), new empirical industrial organization (NEIO), Indonesian food and beverages industry, Data Envelopment Analysis (DEA), system of equations
Heat Transfer Measurement and Modeling in Rigid High-Temperature Reusable Surface Insulation Tiles
Daryabeigi, Kamran; Knutson, Jeffrey R.; Cunnington, George R.
2011-01-01
Heat transfer in rigid reusable surface insulations was investigated. Steady-state thermal conductivity measurements in a vacuum were used to determine the combined contribution of radiation and solid conduction components of heat transfer. Thermal conductivity measurements at higher pressures were then used to estimate the effective insulation characteristic length for gas conduction modeling. The thermal conductivity of the insulation can then be estimated at any temperature and pressure in any gaseous media. The methodology was validated by comparing estimated thermal conductivities with published data on a rigid high-temperature silica reusable surface insulation tile. The methodology was also applied to the alumina enhanced thermal barrier tiles. Thermal contact resistance for thermal conductivity measurements on rigid tiles was also investigated. A technique was developed to effectively eliminate thermal contact resistance on the rigid tile s cold-side surface for the thermal conductivity measurements.
Positive semidefinite matrix completion, universal rigidity and the Strong Arnold Property
M. Laurent (Monique); A. Varvitsiotis (Antonios)
2014-01-01
htmlabstractThis paper addresses the following three topics: positive semidefinite (psd) matrix completions, universal rigidity of frameworks, and the Strong Arnold Property (SAP). We show some strong connections among these topics, using semidefinite programming as unifying theme. Our main
NUMERICAL SIMULATIONS FOR THE CASE OF RIGID ROTATING KINEMATIC COUPLING WITH BIG CLEARANCE
Directory of Open Access Journals (Sweden)
Jan-Cristian GRIGORE
2010-10-01
Full Text Available In this paper an algorithm based on [1] [2] are numerical simulations, achieving generalized coordinates of motion, positions, speeds of a rigid rotating kinematic coupling with big clearance in joint, case without friction
A model for an acoustically driven microbubble inside a rigid tube
Qamar, Adnan; Samtaney, Ravi
2014-01-01
A theoretical framework to model the dynamics of acoustically driven microbubble inside a rigid tube is presented. The proposed model is not a variant of the conventional Rayleigh-Plesset category of models. It is derived from the reduced Navier
Building America Top Innovations 2013 Profile – Exterior Rigid Insulation Best Practices
Energy Technology Data Exchange (ETDEWEB)
none,
2013-09-01
In this Top Innovation profile, field and lab studies by BSC, PHI, and NorthernSTAR characterize the thermal, air, and vapor resistance properties of rigid foam insulation and describe best practices for their use on walls, roofs, and foundations.
National Research Council Canada - National Science Library
Hammons, Michael
1998-01-01
.... The objective of this research was to obtain data on the response of the ng'id pavement slab-joint-foundation system by conducting laboratory-scale experiments on jointed rigid pavement models...
Body fixed frame, rigid gauge rotations and large N random fields in QCD
International Nuclear Information System (INIS)
Levit, S.
1995-01-01
The ''body fixed frame'' with respect to local gauge transformations is introduced. Rigid gauge ''rotations'' in QCD and their Schroedinger equation are studied for static and dynamic quarks. Possible choices of the rigid gauge field configuration corresponding to a non-vanishing static colormagnetic field in the ''body fixed'' frame are discussed. A gauge invariant variational equation is derived in this frame. For large number N of colors the rigid gauge field configuration is regarded as random with maximally random probability distribution under constraints on macroscopic-like quantities. For the uniform magnetic field the joint probability distribution of the field components is determined by maximizing the appropriate entropy under the area law constraint for the Wilson loop. In the quark sector the gauge invariance requires the rigid gauge field configuration to appear not only as a background but also as inducing an instantaneous quark-quark interaction. Both are random in the large N limit. (orig.)