Twisted gastrulation, a BMP antagonist, exacerbates podocyte injury.
Directory of Open Access Journals (Sweden)
Sachiko Yamada
Full Text Available Podocyte injury is the first step in the progression of glomerulosclerosis. Previous studies have demonstrated the beneficial effect of bone morphogenetic protein 7 (Bmp7 in podocyte injury and the existence of native Bmp signaling in podocytes. Local activity of Bmp7 is controlled by cell-type specific Bmp antagonists, which inhibit the binding of Bmp7 to its receptors. Here we show that the product of Twisted gastrulation (Twsg1, a Bmp antagonist, is the central negative regulator of Bmp function in podocytes and that Twsg1 null mice are resistant to podocyte injury. Twsg1 was the most abundant Bmp antagonist in murine cultured podocytes. The administration of Bmp induced podocyte differentiation through Smad signaling, whereas the simultaneous administration of Twsg1 antagonized the effect. The administration of Bmp also inhibited podocyte proliferation, whereas simultaneous administration of Twsg1 antagonized the effect. Twsg1 was expressed in the glomerular parietal cells (PECs and distal nephron of the healthy kidney, and additionally in damaged glomerular cells in a murine model of podocyte injury. Twsg1 null mice exhibited milder hypoalbuminemia and hyperlipidemia, and milder histological changes while maintaining the expression of podocyte markers during podocyte injury model. Taken together, our results show that Twsg1 plays a critical role in the modulation of protective action of Bmp7 on podocytes, and that inhibition of Twsg1 is a promising means of development of novel treatment for podocyte injury.
Twist limits for late twisting double somersaults on trampoline.
Yeadon, M R; Hiley, M J
2017-06-14
An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that could be produced in the second somersault of a double somersault on trampoline using asymmetrical movements of the arms and hips. Lower bounds were placed on the durations of arm and hip angle changes based on performances of a world trampoline champion whose inertia parameters were used in the simulations. The limiting movements were identified as the largest possible odd number of half twists for forward somersaulting takeoffs and even number of half twists for backward takeoffs. Simulations of these two limiting movements were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist at landing after a flight time of 2.0s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that 3½ twists could be produced in the second somersault of a forward piked double somersault with arms abducted 8° from full adduction during the twisting phase and that three twists could be produced in the second somersault of a backward straight double somersault with arms fully adducted to the body. These two movements are at the limits of performance for elite trampolinists. Copyright © 2017 Elsevier Ltd. All rights reserved.
Double scaling limits and twisted non-critical superstrings
International Nuclear Information System (INIS)
Bertoldi, Gaetano
2006-01-01
We consider double-scaling limits of multicut solutions of certain one matrix models that are related to Calabi-Yau singularities of type A and the respective topological B model via the Dijkgraaf-Vafa correspondence. These double-scaling limits naturally lead to a bosonic string with c ≤ 1. We argue that this non-critical string is given by the topologically twisted non-critical superstring background which provides the dual description of the double-scaled little string theory at the Calabi-Yau singularity. The algorithms developed recently to solve a generic multicut matrix model by means of the loop equations allow to show that the scaling of the higher genus terms in the matrix model free energy matches the expected behaviour in the topological B-model. This result applies to a generic matrix model singularity and the relative double-scaling limit. We use these techniques to explicitly evaluate the free energy at genus one and genus two
Intercellular bridges in vertebrate gastrulation.
Directory of Open Access Journals (Sweden)
Luca Caneparo
Full Text Available The developing zebrafish embryo has been the subject of many studies of regional patterning, stereotypical cell movements and changes in cell shape. To better study the morphological features of cells during gastrulation, we generated mosaic embryos expressing membrane attached Dendra2 to highlight cellular boundaries. We find that intercellular bridges join a significant fraction of epiblast cells in the zebrafish embryo, reaching several cell diameters in length and spanning across different regions of the developing embryos. These intercellular bridges are distinct from the cellular protrusions previously reported as extending from hypoblast cells (1-2 cellular diameters in length or epiblast cells (which were shorter. Most of the intercellular bridges were formed at pre-gastrula stages by the daughters of a dividing cell maintaining a membrane tether as they move apart after mitosis. These intercellular bridges persist during gastrulation and can mediate the transfer of proteins between distant cells. These findings reveal a surprising feature of the cellular landscape in zebrafish embryos and open new possibilities for cell-cell communication during gastrulation, with implications for modeling, cellular mechanics, and morphogenetic signaling.
The role of leading twist operators in the Regge and Lorentzian OPE limits
Energy Technology Data Exchange (ETDEWEB)
Costa, Miguel S. [Centro de Física do Porto, Departamento de Física e Astronomia,Faculdade de Ciências da Universidade do Porto,Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Drummond, James [CERN,Geneva 23 (Switzerland); School of Physics and Astronomy, University of Southampton,Highfield, Southampton, SO17 1BJ (United Kingdom); LAPTH, CNRS et Université de Savoie,F-74941 Annecy-le-Vieux Cedex (France); Gonçalves, Vasco; Penedones, João [Centro de Física do Porto, Departamento de Física e Astronomia,Faculdade de Ciências da Universidade do Porto,Rua do Campo Alegre 687, 4169-007 Porto (Portugal)
2014-04-14
We study two kinematical limits, the Regge limit and the Lorentzian OPE limit, of the four-point function of the stress-tensor multiplet in Super Yang-Mills at weak coupling. We explain how both kinematical limits are controlled by the leading twist operators. We use the known expression of the four-point function up to three loops, to extract the pomeron residue at next-to-leading order. Using this data and the known form of pomeron spin up to next-to-leading order, we predict the behaviour of the four-point function in the Regge limit at higher loops. Specifically, we determine the leading log behaviour at any loop order and the next-to-leading log at four loops. Finally, we check the consistency of our results with conformal Regge theory. This leads us to predict the behaviour around J=1 of the OPE coefficient of the spin J leading twist operator in the OPE of two chiral primary operators.
Continuum limit of overlap valence quarks on a twisted mass sea
International Nuclear Information System (INIS)
Cichy, Krzysztof; Herdoiza, Gregorio; Univ. Autonoma de Madrid; Jansen, Karl
2010-12-01
We study a lattice QCD mixed action with overlap valence quarks on two flavours of Wilson maximally twisted mass sea quarks. Employing three different matching conditions to relate both actions to each other, we investigate the continuum limit by using three values of the lattice spacing ranging from a∼0.05 fm to 0.08 fm. A particular emphasis is put on the effect on physical observables of the topological zero modes appearing in the valence overlap operator. We estimate the region of parameter space where the contribution from these zero modes is sufficiently small such that their effects can be safely controlled and a restoration of unitarity of the mixed action in the continuum limit is reached. (orig.)
Continuum limit of overlap valence quarks on a twisted mass sea
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; Jansen, Karl [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC
2010-12-15
We study a lattice QCD mixed action with overlap valence quarks on two flavours of Wilson maximally twisted mass sea quarks. Employing three different matching conditions to relate both actions to each other, we investigate the continuum limit by using three values of the lattice spacing ranging from a{approx}0.05 fm to 0.08 fm. A particular emphasis is put on the effect on physical observables of the topological zero modes appearing in the valence overlap operator. We estimate the region of parameter space where the contribution from these zero modes is sufficiently small such that their effects can be safely controlled and a restoration of unitarity of the mixed action in the continuum limit is reached. (orig.)
Reducing cutoff effects in maximally twisted lattice QCD close to the chiral limit
International Nuclear Information System (INIS)
Frezzotti, R.; Papinutto, M.; Rossi, G.C.; Istituto Nazionale di Fisica Nucleare, Rome; Deutsches Elektronen-Synchrotron
2005-03-01
When analyzed in terms of the Symanzik expansion, the expectation values of multi-local (gauge-invariant) operators with non-trivial continuum limit exhibit in maximally twisted lattice QCD ''infrared divergent'' cutoff effects of the type a 2k /(m π 2 ) h , 2k ≥ h ≥ 1, which become numerically dangerous when the pion mass gets small. We prove that, if the critical mass counter-term is chosen in some ''optimal'' way or, alternatively, the action is O(a) improved a la Symanzik, the leading cutoff effects of this kind (i.e. those with h = 2k) can all be eliminated. Once this is done, the remaining next-to-leading ''infrared divergent'' effects are only of the kind a 2 (a 2 /m π 2 ) k , k ≥ 1. This implies that the continuum extrapolation of lattice results is smooth at least down to values of the quark mass, m q , satisfying the order of magnitude inequality m q > a 2 Λ QCD 3 . (orig.)
The Cardy limit of the topologically twisted index and black strings in AdS{sub 5}
Energy Technology Data Exchange (ETDEWEB)
Hosseini, Seyed Morteza; Nedelin, Anton; Zaffaroni, Alberto [Dipartimento di Fisica, Università di Milano-Bicocca,I-20126 Milano (Italy); INFN, Sezione di Milano-Bicocca,I-20126 Milano (Italy)
2017-04-04
We evaluate the topologically twisted index of a general four-dimensional N=1 gauge theory in the “high-temperature' limit. The index is the partition function for N=1 theories on S{sup 2}×T{sup 2}, with a partial topological twist along S{sup 2}, in the presence of background magnetic fluxes and fugacities for the global symmetries. We show that the logarithm of the index is proportional to the conformal anomaly coefficient of the two-dimensional N=(0,2) SCFTs obtained from the compactification on S{sup 2}. We also present a universal formula for extracting the index from the four-dimensional conformal anomaly coefficient and its derivatives. We give examples based on theories whose holographic duals are black strings in type IIB backgrounds AdS{sub 5}×SE{sub 5}, where SE{sub 5} are five-dimensional Sasaki-Einstein spaces.
TEK twisted gradient flow running coupling
Pérez, Margarita García; Keegan, Liam; Okawa, Masanori
2014-01-01
We measure the running of the twisted gradient flow coupling in the Twisted Eguchi-Kawai (TEK) model, the SU(N) gauge theory on a single site lattice with twisted boundary conditions in the large N limit.
CSIR Research Space (South Africa)
Forbes, A
2010-12-01
Full Text Available Research at the Mathematical Optics Group uses "twisted" light to study new quatum-based information security systems. In order to understand the structure of "twisted" light, it is useful to start with an ordinary light beam with zero twist, namely...
Pathological axes of wound repair: Gastrulation revisited
Directory of Open Access Journals (Sweden)
Aller Maria-Angeles
2010-09-01
Full Text Available Abstract Post-traumatic inflammation is formed by molecular and cellular complex mechanisms whose final goal seems to be injured tissue regeneration. In the skin -an exterior organ of the body- mechanical or thermal injury induces the expression of different inflammatory phenotypes that resemble similar phenotypes expressed during embryo development. Particularly, molecular and cellular mechanisms involved in gastrulation return. This is a developmental phase that delineates the three embryonic germ layers: ectoderm, endoderm and mesoderm. Consequently, in the post-natal wounded skin, primitive functions related with the embryonic mesoderm, i.e. amniotic and yolk sac-derived, are expressed. Neurogenesis and hematogenesis stand out among the primitive function mechanisms involved. Interestingly, in these phases of the inflammatory response, whose molecular and cellular mechanisms are considered as traces of the early phases of the embryonic development, the mast cell, a cell that is supposedly inflammatory, plays a key role. The correlation that can be established between the embryonic and the inflammatory events suggests that the results obtained from the research regarding both great fields of knowledge must be interchangeable to obtain the maximum advantage.
Directory of Open Access Journals (Sweden)
André C. Morandini
2001-06-01
Full Text Available The structure of the ovaries and testes of Nausithoe aurea, reared in the laboratory, is described to update the knowledge of coronate scyphomedusae gametogenesis and early development. The testis is similar to those of other scyphozoans. The organization of the ovary agrees with the description for other coronates, with free oocytes in the mesoglea. The oocytes develop in a limited region of the gastrodermis, and a maturation gradient is observed from this point on. Egg release, embryonic development, and gastrulation mode of Nausithoe aurea are also described. Egg production was continuous for 55 days, and the output of released eggs oscillated without observed cue. Cleavage was holoblastic and adequal, but after the 8-cell stage, the cleavage became pseudospiral. Gastrulation occurred through multipolar ingression and began 24 hours after fertilization.
Larocque, Hugo; Kaminer, Ido; Grillo, Vincenzo; Leuchs, Gerd; Padgett, Miles J.; Boyd, Robert W.; Segev, Mordechai; Karimi, Ebrahim
2018-04-01
Electrons have played a significant role in the development of many fields of physics during the last century. The interest surrounding them mostly involved their wave-like features prescribed by the quantum theory. In particular, these features correctly predict the behaviour of electrons in various physical systems including atoms, molecules, solid-state materials, and even in free space. Ten years ago, new breakthroughs were made, arising from the new ability to bestow orbital angular momentum (OAM) to the wave function of electrons. This quantity, in conjunction with the electron's charge, results in an additional magnetic property. Owing to these features, OAM-carrying, or twisted, electrons can effectively interact with magnetic fields in unprecedented ways and have motivated materials scientists to find new methods for generating twisted electrons and measuring their OAM content. Here, we provide an overview of such techniques along with an introduction to the exciting dynamics of twisted electrons.
Dickens, Charles
2005-01-01
Oliver Twist is one of Dickens's most popular novels, with many famous film, television and musical adaptations. It is a classic story of good against evil, packed with humour and pathos, drama and suspense, in which the orphaned Oliver is brought up in a harsh workhouse, and then taken in and
A Transformation Called "Twist"
Hwang, Daniel
2010-01-01
The transformations found in secondary mathematics curriculum are typically limited to stretches and translations (e.g., ACARA, 2010). Advanced students may find the transformation, twist, to be of further interest. As most available resources are written for professional-level readers, this article is intended to be an introduction accessible to…
Twisted Gastrulation as a BMP Modulator during Mammary Gland Development and Tumorigenesis
2014-05-01
tissues ( Bonilla -Claudio et al., 2012). In WT TEBs (Fig. 8A–D) and mature ducts (Fig. 8I–L) almost all luminal cells expressed GATA-3. In contrast, Twsg1...PubMed: 12952901] Bonilla -Claudio M, Wang J, Bai Y, Klysik E, Selever J, Martin JF. Bmp signaling regulates a dosedependent transcriptional...deficient mice. Arch Oral Biol. 2006; 51:433–8. [PubMed: 16289463] Metallo CM, Ji L, de Pablo JJ, Palecek SP. Retinoic Acid and Bone Morphogenetic
DEFF Research Database (Denmark)
Pedersen, Gitte Alsing; Jensen, Lisbeth Krüger; Fankhauser, A.
2008-01-01
Nineteen samples of food in glass jars with twist closures were collected by the national food inspectors at Danish food producers and a few importers, focusing on fatty food, such as vegetables in oil, herring in dressing or pickle, soft spreadable cheese, cream, dressings, peanut butter, sauces...... and infant food. The composition of the plasticizers in the gaskets was analysed by gas chromatography with flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Epoxidized soybean oil (ESBO) and phthalates were determined in the homogenized food samples. ESBO...... was the principal plasticizer in five of the gaskets; in 14 it was phthalates. ESBO was found in seven of the food samples at concentrations from 6 to 100 mg kg(-1). The highest levels (91-100 mg kg(-1)) were in oily foods such as garlic, chilli or olives in oil. Phthalates, i.e. di-iso-decylphthalate (DIDP) and di...
Physical-chemical mechanisms of pattern formation during gastrulation
Bozorgui, Behnaz; Kolomeisky, Anatoly B.; Teimouri, Hamid
2018-03-01
Gastrulation is a fundamental phase during the biological development of most animals when a single layer of identical embryo cells is transformed into a three-layer structure, from which the organs start to develop. Despite a remarkable progress in quantifying the gastrulation processes, molecular mechanisms of these processes remain not well understood. Here we theoretically investigate early spatial patterning in a geometrically confined colony of embryonic stem cells. Using a reaction-diffusion model, a role of Bone-Morphogenetic Protein 4 (BMP4) signaling pathway in gastrulation is specifically analyzed. Our results show that for slow diffusion rates of BMP4 molecules, a new length scale appears, which is independent of the size of the system. This length scale separates the central region of the colony with uniform low concentrations of BMP molecules from the region near the colony edge where the concentration of signaling molecules is elevated. The roles of different components of the signaling pathway are also explained. Theoretical results are consistent with recent in vitro experiments, providing microscopic explanations for some features of early embryonic spatial patterning. Physical-chemical mechanisms of these processes are discussed.
Twisted supersymmetry: Twisted symmetry versus renormalizability
International Nuclear Information System (INIS)
Dimitrijevic, Marija; Nikolic, Biljana; Radovanovic, Voja
2011-01-01
We discuss a deformation of superspace based on a Hermitian twist. The twist implies a *-product that is noncommutative, Hermitian and finite when expanded in a power series of the deformation parameter. The Leibniz rule for the twisted supersymmetry transformations is deformed. A minimal deformation of the Wess-Zumino action is proposed and its renormalizability properties are discussed. There is no tadpole contribution, but the two-point function diverges. We speculate that the deformed Leibniz rule, or more generally the twisted symmetry, interferes with renormalizability properties of the model. We discuss different possibilities to render a renormalizable model.
International Nuclear Information System (INIS)
Shindler, A.
2007-07-01
I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the effects of these discretization errors on the phase structure for Wilson-like fermions in the chiral limit. The possibility to use in lattice simulations different lattice actions for sea and valence quarks to ease the renormalization patterns of phenomenologically relevant local operators, is also discussed. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Shindler, A. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2007-07-15
I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the effects of these discretization errors on the phase structure for Wilson-like fermions in the chiral limit. The possibility to use in lattice simulations different lattice actions for sea and valence quarks to ease the renormalization patterns of phenomenologically relevant local operators, is also discussed. (orig.)
Mesoderm layer formation in Xenopus and Drosophila gastrulation
International Nuclear Information System (INIS)
Winklbauer, Rudolf; Müller, H-Arno J
2011-01-01
During gastrulation, the mesoderm spreads out between ectoderm and endoderm to form a mesenchymal cell layer. Surprisingly the underlying principles of mesoderm layer formation are very similar in evolutionarily distant species like the fruit fly, Drosophila melanogaster, and the frog, Xenopus laevis, in which the molecular and the cellular basis of mesoderm layer formation have been extensively studied. Complementary expression of growth factors in the ectoderm and their receptors in the mesoderm act to orient cellular protrusive activities and direct cell movement, leading to radial cell intercalation and the spreading of the mesoderm layer. This mechanism is contrasted with generic physical mechanisms of tissue spreading that consider the adhesive and physical properties of the cells and tissues. Both mechanisms need to be integrated to orchestrate mesenchymal morphogenesis
Joy, Lija K.; George, Merin; Alex, Javeesh; Aravind, Arun; Sajan, D.; Vinitha, G.
2018-03-01
Single crystals of L-Glutamic acid hydrochloride (LGHCl) were grown by slow evaporation solution technique and good crystalline perfection was confirmed by Powder X-ray diffraction studies. The complete vibrational studies of the compound were analyzed by FT-IR, FT-Raman and UV-visible spectra combined with Normal Coordinate Analysis (NCA) following the scaled quantum mechanical force field methodology and density functional theory (DFT). Twisted Intramolecular Charge Transfer (ICT) occurs due to the presence of strong ionic intra-molecular Nsbnd H⋯O hydrogen bonding was confirmed by Hirshfeld Surface analysis. The existence of intermolecular Nsbnd H⋯Cl hydrogen bonds due to the interaction between the lone pair of oxygen with the antibonding orbital was established by NBO analysis. The Z-scan result indicated that the title molecule exhibits saturable absorption behavior. The attractive third-order nonlinear properties suggest that LGHCl can be a promising candidate for the design and development devices for optical limiting applications. LGHCL exhibits distinct emission in the blue region of the fluorescence lifetime which proves to be a potential candidate for blue- Organic light-emitting diodes (OLEDs) fabrication.
Twisting perturbed parafermions
Directory of Open Access Journals (Sweden)
A.V. Belitsky
2017-07-01
Full Text Available The near-collinear expansion of scattering amplitudes in maximally supersymmetric Yang–Mills theory at strong coupling is governed by the dynamics of stings propagating on the five sphere. The pentagon transitions in the operator product expansion which systematize the series get reformulated in terms of matrix elements of branch-point twist operators in the two-dimensional O(6 nonlinear sigma model. The facts that the latter is an asymptotically free field theory and that there exists no local realization of twist fields prevents one from explicit calculation of their scaling dimensions and operator product expansion coefficients. This complication is bypassed making use of the equivalence of the sigma model to the infinite-level limit of WZNW models perturbed by current–current interactions, such that one can use conformal symmetry and conformal perturbation theory for systematic calculations. Presently, to set up the formalism, we consider the O(3 sigma model which is reformulated as perturbed parafermions.
Generalised twisted partition functions
Petkova, V B
2001-01-01
We consider the set of partition functions that result from the insertion of twist operators compatible with conformal invariance in a given 2D Conformal Field Theory (CFT). A consistency equation, which gives a classification of twists, is written and solved in particular cases. This generalises old results on twisted torus boundary conditions, gives a physical interpretation of Ocneanu's algebraic construction, and might offer a new route to the study of properties of CFT.
Twisted network programming essentials
Fettig, Abe
2005-01-01
Twisted Network Programming Essentials from O'Reilly is a task-oriented look at this new open source, Python-based technology. The book begins with recommendations for various plug-ins and add-ons to enhance the basic package as installed. It then details Twisted's collection simple network protocols, and helper utilities. The book also includes projects that let you try out the Twisted framework for yourself. For example, you'll find examples of using Twisted to build web services applications using the REST architecture, using XML-RPC, and using SOAP. Written for developers who want to s
Four-point functions with a twist
Energy Technology Data Exchange (ETDEWEB)
Bargheer, Till [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group
2017-01-15
We study the OPE of correlation functions of local operators in planar N=4 super Yang-Mills theory. The considered operators have an explicit spacetime dependence that is defined by twisting the translation generators with certain R-symmetry generators. We restrict to operators that carry a small number of excitations above the twisted BMN vacuum. The OPE limit of the four-point correlator is dominated by internal states with few magnons on top of the vacuum. The twisting directly couples all spacetime dependence of the correlator to these magnons. We analyze the OPE in detail, and single out the extremal states that have to cancel all double-trace contributions.
PTBP1 is required for embryonic development before gastrulation.
Suckale, Jakob; Wendling, Olivia; Masjkur, Jimmy; Jäger, Melanie; Münster, Carla; Anastassiadis, Konstantinos; Stewart, A Francis; Solimena, Michele
2011-02-17
Polypyrimidine-tract binding protein 1 (PTBP1) is an important cellular regulator of messenger RNAs influencing the alternative splicing profile of a cell as well as its mRNA stability, location and translation. In addition, it is diverted by some viruses to facilitate their replication. Here, we used a novel PTBP1 knockout mouse to analyse the tissue expression pattern of PTBP1 as well as the effect of its complete removal during development. We found evidence of strong PTBP1 expression in embryonic stem cells and throughout embryonic development, especially in the developing brain and spinal cord, the olfactory and auditory systems, the heart, the liver, the kidney, the brown fat and cartilage primordia. This widespread distribution points towards a role of PTBP1 during embryonic development. Homozygous offspring, identified by PCR and immunofluorescence, were able to implant but were arrested or retarded in growth. At day 7.5 of embryonic development (E7.5) the null mutants were about 5x smaller than the control littermates and the gap in body size widened with time. At mid-gestation, all homozygous embryos were resorbed/degraded. No homozygous mice were genotyped at E12 and the age of weaning. Embryos lacking PTBP1 did not display differentiation into the 3 germ layers and cavitation of the epiblast, which are hallmarks of gastrulation. In addition, homozygous mutants displayed malformed ectoplacental cones and yolk sacs, both early supportive structure of the embryo proper. We conclude that PTBP1 is not required for the earliest isovolumetric divisions and differentiation steps of the zygote up to the formation of the blastocyst. However, further post-implantation development requires PTBP1 and stalls in homozygous null animals with a phenotype of dramatically reduced size and aberration in embryonic and extra-embryonic structures.
Actomyosin-based Self-organization of cell internalization during C. elegans gastrulation
Directory of Open Access Journals (Sweden)
Pohl Christian
2012-11-01
Full Text Available Abstract Background Gastrulation is a key transition in embryogenesis; it requires self-organized cellular coordination, which has to be both robust to allow efficient development and plastic to provide adaptability. Despite the conservation of gastrulation as a key event in Metazoan embryogenesis, the morphogenetic mechanisms of self-organization (how global order or coordination can arise from local interactions are poorly understood. Results We report a modular structure of cell internalization in Caenorhabditis elegans gastrulation that reveals mechanisms of self-organization. Cells that internalize during gastrulation show apical contractile flows, which are correlated with centripetal extensions from surrounding cells. These extensions converge to seal over the internalizing cells in the form of rosettes. This process represents a distinct mode of monolayer remodeling, with gradual extrusion of the internalizing cells and simultaneous tissue closure without an actin purse-string. We further report that this self-organizing module can adapt to severe topological alterations, providing evidence of scalability and plasticity of actomyosin-based patterning. Finally, we show that globally, the surface cell layer undergoes coplanar division to thin out and spread over the internalizing mass, which resembles epiboly. Conclusions The combination of coplanar division-based spreading and recurrent local modules for piecemeal internalization constitutes a system-level solution of gradual volume rearrangement under spatial constraint. Our results suggest that the mode of C. elegans gastrulation can be unified with the general notions of monolayer remodeling and with distinct cellular mechanisms of actomyosin-based morphogenesis.
Twisted classical Poincare algebras
International Nuclear Information System (INIS)
Lukierski, J.; Ruegg, H.; Tolstoy, V.N.; Nowicki, A.
1993-11-01
We consider the twisting of Hopf structure for classical enveloping algebra U(g), where g is the inhomogeneous rotations algebra, with explicite formulae given for D=4 Poincare algebra (g=P 4 ). The comultiplications of twisted U F (P 4 ) are obtained by conjugating primitive classical coproducts by F element of U(c)xU(c), where c denotes any Abelian subalgebra of P 4 , and the universal R-matrices for U F (P 4 ) are triangular. As an example we show that the quantum deformation of Poincare algebra recently proposed by Chaichian and Demiczev is a twisted classical Poincare algebra. The interpretation of twisted Poincare algebra as describing relativistic symmetries with clustered 2-particle states is proposed. (orig.)
Extension-twist coupling of composite circular tubes with application to tilt rotor blade design
Nixon, Mark W.
1987-01-01
This investigation was conducted to determine if twist deformation required for the design of full-scale extension-twist-coupled tilt-rotor blades can be achieved within material design limit loads, and to demonstrate the accuracy of a coupled-beam analysis in predicting twist deformations. Two extension-twist-coupled tilt-rotor blade designs were developed based on theoretically optimum aerodynamic twist distributions. The designs indicated a twist rate requirement of between .216 and .333 deg/in. Agreement between axial tests and analytical predictions was within 10 percent at design limit loads. Agreement between the torsion tests and predictions was within 11 percent.
Energy Technology Data Exchange (ETDEWEB)
Villalobos Baillie, Orlando
1988-12-15
In the quantum chromodynamics (QCD) candidate theory of interquark forces, calculations involve summing the effects from many different possible quark/gluon interactions. In addition to the 'leading term' frequently used as the basis for QCD calculations, additional contributions — so-called 'higher twists' — are modulated by powers of kinematical factors. An illuminating international workshop to discuss higher twist QCD was held at the College de France, Paris, from 21-23 September.
New twist on artificial muscles.
Haines, Carter S; Li, Na; Spinks, Geoffrey M; Aliev, Ali E; Di, Jiangtao; Baughman, Ray H
2016-10-18
Lightweight artificial muscle fibers that can match the large tensile stroke of natural muscles have been elusive. In particular, low stroke, limited cycle life, and inefficient energy conversion have combined with high cost and hysteretic performance to restrict practical use. In recent years, a new class of artificial muscles, based on highly twisted fibers, has emerged that can deliver more than 2,000 J/kg of specific work during muscle contraction, compared with just 40 J/kg for natural muscle. Thermally actuated muscles made from ordinary polymer fibers can deliver long-life, hysteresis-free tensile strokes of more than 30% and torsional actuation capable of spinning a paddle at speeds of more than 100,000 rpm. In this perspective, we explore the mechanisms and potential applications of present twisted fiber muscles and the future opportunities and challenges for developing twisted muscles having improved cycle rates, efficiencies, and functionality. We also demonstrate artificial muscle sewing threads and textiles and coiled structures that exhibit nearly unlimited actuation strokes. In addition to robotics and prosthetics, future applications include smart textiles that change breathability in response to temperature and moisture and window shutters that automatically open and close to conserve energy.
Hayashi, Kentaro; Yamamoto, Takamasa S; Ueno, Naoto
2018-02-05
During the gastrulation stage in animal embryogenesis, the cells leading the axial mesoderm migrate toward the anterior side of the embryo, vigorously extending cell protrusions such as lamellipodia. It is thought that the leading cells sense gradients of chemoattractants emanating from the ectodermal cells and translate them to initiate and maintain the cell movements necessary for gastrulation. However, it is unclear how the extracellular information is converted to the intracellular chemical reactions that lead to motion. Here we demonstrated that intracellular Ca 2+ levels in the protrusion-forming leading cells are markedly higher than those of the following cells and the axial mesoderm cells. We also showed that inhibiting the intracellular Ca 2+ significantly retarded the gastrulation cell movements, while increasing the intracellular Ca 2+ with an ionophore enhanced the migration. We further found that the ionophore treatment increased the active form of the small GTPase Rac1 in these cells. Our results suggest that transient intracellular Ca 2+ signals play an essential role in the active cell migration during gastrulation.
New insights from a high-resolution look at gastrulation in the sea urchin, Lytechinus variegatus.
Martik, Megan L; McClay, David R
2017-12-01
Gastrulation is a complex orchestration of movements by cells that are specified early in development. Until now, classical convergent extension was considered to be the main contributor to sea urchin archenteron extension, and the relative contributions of cell divisions were unknown. Active migration of cells along the axis of extension was also not considered as a major factor in invagination. Cell transplantations plus live imaging were used to examine endoderm cell morphogenesis during gastrulation at high-resolution in the optically clear sea urchin embryo. The invagination sequence was imaged throughout gastrulation. One of the eight macromeres was replaced by a fluorescently labeled macromere at the 32 cell stage. At gastrulation those patches of fluorescent endoderm cell progeny initially about 4 cells wide, released a column of cells about 2 cells wide early in gastrulation and then often this column narrowed to one cell wide by the end of archenteron lengthening. The primary movement of the column of cells was in the direction of elongation of the archenteron with the narrowing (convergence) occurring as one of the two cells moved ahead of its neighbor. As the column narrowed, the labeled endoderm cells generally remained as a contiguous population of cells, rarely separated by intrusion of a lateral unlabeled cell. This longitudinal cell migration mechanism was assessed quantitatively and accounted for almost 90% of the elongation process. Much of the extension was the contribution of Veg2 endoderm with a minor contribution late in gastrulation by Veg1 endoderm cells. We also analyzed the contribution of cell divisions to elongation. Endoderm cells in Lytechinus variagatus were determined to go through approximately one cell doubling during gastrulation. That doubling occurs without a net increase in cell mass, but the question remained as to whether oriented divisions might contribute to archenteron elongation. We learned that indeed there was a biased
Directory of Open Access Journals (Sweden)
Swapnalee Sarmah
2013-08-01
Fetal alcohol spectrum disorder (FASD occurs when pregnant mothers consume alcohol, causing embryonic ethanol exposure and characteristic birth defects that include craniofacial, neural and cardiac defects. Gastrulation is a particularly sensitive developmental stage for teratogen exposure, and zebrafish is an outstanding model to study gastrulation and FASD. Epiboly (spreading blastomere cells over the yolk cell, prechordal plate migration and convergence/extension cell movements are sensitive to early ethanol exposure. Here, experiments are presented that characterize mechanisms of ethanol toxicity on epiboly and gastrulation. Epiboly mechanisms include blastomere radial intercalation cell movements and yolk cell microtubule cytoskeleton pulling the embryo to the vegetal pole. Both of these processes were disrupted by ethanol exposure. Ethanol effects on cell migration also indicated that cell adhesion was affected, which was confirmed by cell aggregation assays. E-cadherin cell adhesion molecule expression was not affected by ethanol exposure, but E-cadherin distribution, which controls epiboly and gastrulation, was changed. E-cadherin was redistributed into cytoplasmic aggregates in blastomeres and dramatically redistributed in the extraembryonic yolk cell. Gene expression microarray analysis was used to identify potential causative factors for early development defects, and expression of the cell adhesion molecule protocadherin-18a (pcdh18a, which controls epiboly, was significantly reduced in ethanol exposed embryos. Injecting pcdh18a synthetic mRNA in ethanol treated embryos partially rescued epiboly cell movements, including enveloping layer cell shape changes. Together, data show that epiboly and gastrulation defects induced by ethanol are multifactorial, and include yolk cell (extraembryonic tissue microtubule cytoskeleton disruption and blastomere adhesion defects, in part caused by reduced pcdh18a expression.
Twisted Acceleration-Enlarged Newton-Hooke Hopf Algebras
International Nuclear Information System (INIS)
Daszkiewicz, M.
2010-01-01
Ten Abelian twist deformations of acceleration-enlarged Newton-Hooke Hopf algebra are considered. The corresponding quantum space-times are derived as well. It is demonstrated that their contraction limit τ → ∞ leads to the new twisted acceleration-enlarged Galilei spaces. (author)
Twisted electron-acoustic waves in plasmas
International Nuclear Information System (INIS)
Aman-ur-Rehman; Ali, S.; Khan, S. A.; Shahzad, K.
2016-01-01
In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number q_e_f_f accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping rate of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.
DEFF Research Database (Denmark)
Yiu, Man Lung; Jensen, Christian Søndergaard; Xuegang, Huang
2008-01-01
-based matching generally fall short in offering practical query accuracy guarantees. Our proposed framework, called SpaceTwist, rectifies these shortcomings for k nearest neighbor (kNN) queries. Starting with a location different from the user's actual location, nearest neighbors are retrieved incrementally...
Arutyunov, G.E.; de Leeuw, M.; van Tongeren, S.J.
2010-01-01
We study finite-size corrections to the magnon dispersion relation in three models which differ from string theory on AdS5 x S5 in their boundary conditions. Asymptotically, this is accomplished by twisting the transfer matrix in a way which manifestly preserves integrability. In model I all
Zhang, Ying; Shao, Ming; Wang, Lifeng; Liu, Zhongzhen; Gao, Ming; Liu, Chao; Zhang, Hongwei
2010-06-01
To explore the toxic effects of ethanol on axis formation during embryogenesis, zebrafish embryos at different developmental stages were treated with 3% ethanol for 3h. The effects of ethanol exposure appeared to be stage-dependent. The dome stage embryo was most sensible to form posterior split axes upon ethanol exposure. Morphological and histological observations and whole-mount in situ hybridization results showed that ethanol exposure at this stage caused a general gastrulation delay, and induced double notochords, double neural tubes and two sets of somites in the posterior trunk. Mechanistically, no ectopic organizer was found by examining the expression patterns of dorsoventral markers including goosecoid, chordin and eve1 at the onset of gastrulation. However, radial intercalation, epiboly and convergence extension were inhibited by ethanol exposure as revealed by cell labeling, phenotypic observation and the expression patterns of axial or paraxial markers. Further investigation showed that the cell aggregation might be affected by ethanol exposure, as indicated by the much more scattered expression pattern of chordin, eve1 and wnt11 at the early gastrula stage, and the discontinuous gsc positive cells during migration. These results imply that ethanol might affect cell movement before and during gastrulation and as a consequence, induces a split axes phenotype. Copyright 2010 ISDN. Published by Elsevier Ltd. All rights reserved.
Involvement of l(-)-rhamnose in sea urchin gastrulation. Part II: α-l-Rhamnosidase.
Liang, Jing; Aleksanyan, Heghush; Metzenberg, Stan; Oppenheimer, Steven B
2016-06-01
The sea urchin embryo is recognized as a model system to reveal developmental mechanisms involved in human health and disease. In Part I of this series, six carbohydrates were tested for their effects on gastrulation in embryos of the sea urchin Lytechinus pictus. Only l-rhamnose caused dramatic increases in the numbers of unattached archenterons and exogastrulated archenterons in living, swimming embryos. It was found that at 30 h post-fertilization the l-rhamnose had an unusual inverse dose-dependent effect, with low concentrations (1-3 mM) interfering with development and higher concentrations (30 mM) having little to no effect on normal development. In this study, embryos were examined for inhibition of archenteron development after treatment with α-l-rhamnosidase, an endoglycosidase that removes terminal l-rhamnose sugars from glycans. It was observed that the enzyme had profound effects on gastrulation, an effect that could be suppressed by addition of l-rhamnose as a competitive inhibitor. The involvement of l-rhamnose-containing glycans in sea urchin gastrulation was unexpected, since there are no characterized biosynthetic pathways for rhamnose utilization in animals. It is possible there exists a novel l-rhamnose-containing glycan in sea urchins, or that the enzyme and sugar interfere with the function of rhamnose-binding lectins, which are components of the innate immune system in many vertebrate and invertebrate species.
Morphological diversity of blastula formation and gastrulation in temnopleurid sea urchins.
Kitazawa, Chisato; Fujii, Tsubasa; Egusa, Yuji; Komatsu, Miéko; Yamanaka, Akira
2016-11-15
Embryos of temnopleurid sea urchins exhibit species-specific morphologies. While Temnopleurus toreumaticus has a wrinkled blastula and then invaginates continuously at gastrulation, others have a smooth blastula and their invagination is stepwise. We studied blastula and gastrula formation in four temnopleurids using light and scanning electron microscopy to clarify the mechanisms producing these differences. Unlike T. toreumaticus, blastomeres of mid-blastulae in T. reevesii, T. hardwickii and Mespilia globulus formed pseudopods. Before primary mesenchyme cells ingressed, embryos developed an area of orbicular cells in the vegetal plate. The cells surrounding the orbicular cells extended pseudopods toward the orbicular cell area in three Temnopleurus species. In T. toreumaticus, the extracellular matrix was well-developed and developed a hole-like structure that was not formed in others. Gastrulation of T. reevesii, T. hardwickii and M. globulus was stepwise, suggesting that differences of gastrulation are caused by all or some of the following factors: change of cell shape, rearrangement, pushing up and towing of cells. We conclude that (1) many aspects of early morphogenesis differ even among very closely related sea urchins with indirect development and (2) many of these differences may be caused by the cell shape and structure of blastomeres or by differences in extracellular matrix composition. © 2016. Published by The Company of Biologists Ltd.
Morphological diversity of blastula formation and gastrulation in temnopleurid sea urchins
Directory of Open Access Journals (Sweden)
Chisato Kitazawa
2016-11-01
Full Text Available Embryos of temnopleurid sea urchins exhibit species-specific morphologies. While Temnopleurus toreumaticus has a wrinkled blastula and then invaginates continuously at gastrulation, others have a smooth blastula and their invagination is stepwise. We studied blastula and gastrula formation in four temnopleurids using light and scanning electron microscopy to clarify the mechanisms producing these differences. Unlike T. toreumaticus, blastomeres of mid-blastulae in T. reevesii, T. hardwickii and Mespilia globulus formed pseudopods. Before primary mesenchyme cells ingressed, embryos developed an area of orbicular cells in the vegetal plate. The cells surrounding the orbicular cells extended pseudopods toward the orbicular cell area in three Temnopleurus species. In T. toreumaticus, the extracellular matrix was well-developed and developed a hole-like structure that was not formed in others. Gastrulation of T. reevesii, T. hardwickii and M. globulus was stepwise, suggesting that differences of gastrulation are caused by all or some of the following factors: change of cell shape, rearrangement, pushing up and towing of cells. We conclude that (1 many aspects of early morphogenesis differ even among very closely related sea urchins with indirect development and (2 many of these differences may be caused by the cell shape and structure of blastomeres or by differences in extracellular matrix composition.
Processing mechanics of alternate twist ply (ATP) yarn technology
Elkhamy, Donia Said
Ply yarns are important in many textile manufacturing processes and various applications. The primary process used for producing ply yarns is cabling. The speed of cabling is limited to about 35m/min. With the world's increasing demands of ply yarn supply, cabling is incompatible with today's demand activated manufacturing strategies. The Alternate Twist Ply (ATP) yarn technology is a relatively new process for producing ply yarns with improved productivity and flexibility. This technology involves self plying of twisted singles yarn to produce ply yarn. The ATP process can run more than ten times faster than cabling. To implement the ATP process to produce ply yarns there are major quality issues; uniform Twist Profile and yarn Twist Efficiency. The goal of this thesis is to improve these issues through process modeling based on understanding the physics and processing mechanics of the ATP yarn system. In our study we determine the main parameters that control the yarn twist profile. Process modeling of the yarn twist across different process zones was done. A computational model was designed to predict the process parameters required to achieve a square wave twist profile. Twist efficiency, a measure of yarn torsional stability and bulk, is determined by the ratio of ply yarn twist to singles yarn twist. Response Surface Methodology was used to develop the processing window that can reproduce ATP yarns with high twist efficiency. Equilibrium conditions of tensions and torques acting on the yarns at the self ply point were analyzed and determined the pathway for achieving higher twist efficiency. Mechanistic modeling relating equilibrium conditions to the twist efficiency was developed. A static tester was designed to zoom into the self ply zone of the ATP yarn. A computer controlled, prototypic ATP machine was constructed and confirmed the mechanistic model results. Optimum parameters achieving maximum twist efficiency were determined in this study. The
Directory of Open Access Journals (Sweden)
Daijiro Fukuda
2004-01-01
Full Text Available Using diagrammatic pictures of tensor contractions, we consider a Hopf algebra (Aop⊗ℛλA** twisted by an element ℛλ∈A*⊗Aop corresponding to a Hopf algebra morphism λ:A→A. We show that this Hopf algebra is quasitriangular with the universal R-matrix coming from ℛλ when λ2=idA, generalizing the quantum double construction which corresponds to the case λ=idA.
Electronic and Optical Properties of Twisted Bilayer Graphene
Huang, Shengqiang
The ability to isolate single atomic layers of van der Waals materials has led to renewed interest in the electronic and optical properties of these materials as they can be fundamentally different at the monolayer limit. Moreover, these 2D crystals can be assembled together layer by layer, with controllable sequence and orientation, to form artificial materials that exhibit new features that are not found in monolayers nor bulk. Twisted bilayer graphene is one such prototype system formed by two monolayer graphene layers placed on top of each other with a twist angle between their lattices, whose electronic band structure depends on the twist angle. This thesis presents the efforts to explore the electronic and optical properties of twisted bilayer graphene by Raman spectroscopy and scanning tunneling microscopy measurements. We first synthesize twisted bilayer graphene with various twist angles via chemical vapor deposition. Using a combination of scanning tunneling microscopy and Raman spectroscopy, the twist angles are determined. The strength of the Raman G peak is sensitive to the electronic band structure of twisted bilayer graphene and therefore we use this peak to monitor changes upon doping. Our results demonstrate the ability to modify the electronic and optical properties of twisted bilayer graphene with doping. We also fabricate twisted bilayer graphene by controllable stacking of two graphene monolayers with a dry transfer technique. For twist angles smaller than one degree, many body interactions play an important role. It requires eight electrons per moire unit cell to fill up each band instead of four electrons in the case of a larger twist angle. For twist angles smaller than 0.4 degree, a network of domain walls separating AB and BA stacking regions forms, which are predicted to host topologically protected helical states. Using scanning tunneling microscopy and spectroscopy, these states are confirmed to appear on the domain walls when inversion
Automatic O(a) improvement for twisted mass QCD in the presence of spontaneous symmetry breaking
International Nuclear Information System (INIS)
Aoki, Sinya; Baer, Oliver
2006-01-01
In this paper we present a proof for automatic O(a) improvement in twisted mass lattice QCD at maximal twist, which uses only the symmetries of the leading part in the Symanzik effective action. In the process of the proof we clarify that the twist angle is dynamically determined by vacuum expectation values in the Symanzik theory. For maximal twist according to this definition, we show that scaling violations of all quantities which have nonzero values in the continuum limit are even in a. In addition, using Wilson chiral perturbation theory, we investigate this definition for maximal twist and compare it to other definitions which were already employed in actual simulations
Shp2 knockdown and Noonan/LEOPARD mutant Shp2-induced gastrulation defects.
Directory of Open Access Journals (Sweden)
Chris Jopling
2007-12-01
Full Text Available Shp2 is a cytoplasmic protein-tyrosine phosphatase that is essential for normal development. Activating and inactivating mutations have been identified in humans to cause the related Noonan and LEOPARD syndromes, respectively. The cell biological cause of these syndromes remains to be determined. We have used the zebrafish to assess the role of Shp2 in early development. Here, we report that morpholino-mediated knockdown of Shp2 in zebrafish resulted in defects during gastrulation. Cell tracing experiments demonstrated that Shp2 knockdown induced defects in convergence and extension cell movements. In situ hybridization using a panel of markers indicated that cell fate was not affected by Shp2 knock down. The Shp2 knockdown-induced defects were rescued by active Fyn and Yes and by active RhoA. We generated mutants of Shp2 with mutations that were identified in human patients with Noonan or LEOPARD Syndrome and established that Noonan Shp2 was activated and LEOPARD Shp2 lacked catalytic protein-tyrosine phosphatase activity. Expression of Noonan or LEOPARD mutant Shp2 in zebrafish embryos induced convergence and extension cell movement defects without affecting cell fate. Moreover, these embryos displayed craniofacial and cardiac defects, reminiscent of human symptoms. Noonan and LEOPARD mutant Shp2s were not additive nor synergistic, consistent with the mutant Shp2s having activating and inactivating roles in the same signaling pathway. Our results demonstrate that Shp2 is required for normal convergence and extension cell movements during gastrulation and that Src family kinases and RhoA were downstream of Shp2. Expression of Noonan or LEOPARD Shp2 phenocopied the craniofacial and cardiac defects of human patients. The finding that defective Shp2 signaling induced cell movement defects as early as gastrulation may have implications for the monitoring and diagnosis of Noonan and LEOPARD syndrome.
Pentachlorophenol exposure causes Warburg-like effects in zebrafish embryos at gastrulation stage
International Nuclear Information System (INIS)
Xu, Ting; Zhao, Jing; Hu, Ping; Dong, Zhangji; Li, Jingyun; Zhang, Hongchang; Yin, Daqiang; Zhao, Qingshun
2014-01-01
Pentachlorophenol (PCP) is a prevalent pollutant in the environment and has been demonstrated to be a serious toxicant to humans and animals. However, little is known regarding the molecular mechanism underlying its toxic effects on vertebrate early development. To explore the impacts and underlying mechanisms of PCP on early development, zebrafish (Danio rerio) embryos were exposed to PCP at concentrations of 0, 20 and 50 μg/L, and microscopic observation and cDNA microarray analysis were subsequently conducted at gastrulation stage. The morphological observations revealed that PCP caused a developmental delay of zebrafish embryos in a concentration-dependent manner. Transcriptomic data showed that 50 μg/L PCP treatment resulted in significant changes in gene expression level, and the genes involved in energy metabolism and cell behavior were identified based on gene functional enrichment analysis. The energy production of embryos was influenced by PCP via the activation of glycolysis along with the inhibition of oxidative phosphorylation (OXPHOS). The results suggested that PCP acts as an inhibitor of OXPHOS at 8 hpf (hours postfertilization). Consistent with the activated glycolysis, the cell cycle activity of PCP-treated embryos was higher than the controls. These characteristics are similar to the Warburg effect, which occurs in human tumors. The microinjection of exogenous ATP confirmed that an additional energy supply could rescue PCP-treated embryos from the developmental delay due to the energy deficit. Taken together, our results demonstrated that PCP causes a Warburg-like effect on zebrafish embryos during gastrulation, and the affected embryos had the phenotype of developmental delay. - Highlights: • We treat zebrafish embryos with PCP at gastrula stage. • PCP acts as an oxidative phosphorylation inhibitor, not an uncoupler, in gastrulation. • Exogenous ATP injection will rescue the development of effected embryos. • The transcriptome of PCP
Pentachlorophenol exposure causes Warburg-like effects in zebrafish embryos at gastrulation stage
Energy Technology Data Exchange (ETDEWEB)
Xu, Ting; Zhao, Jing [Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Technology, Tongji University, Shanghai 200092 (China); Hu, Ping [Key Laboratory of Model Animal for Disease Study, Ministry of Education, Model Animal Research Center, Nanjing University, Nanjing 210061 (China); State Key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Nanjing 210029 (China); Dong, Zhangji; Li, Jingyun [Key Laboratory of Model Animal for Disease Study, Ministry of Education, Model Animal Research Center, Nanjing University, Nanjing 210061 (China); Zhang, Hongchang [Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Technology, Tongji University, Shanghai 200092 (China); Yin, Daqiang, E-mail: yindq@tongji.edu.cn [Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Technology, Tongji University, Shanghai 200092 (China); Zhao, Qingshun, E-mail: qingshun@nju.edu.cn [Key Laboratory of Model Animal for Disease Study, Ministry of Education, Model Animal Research Center, Nanjing University, Nanjing 210061 (China)
2014-06-01
Pentachlorophenol (PCP) is a prevalent pollutant in the environment and has been demonstrated to be a serious toxicant to humans and animals. However, little is known regarding the molecular mechanism underlying its toxic effects on vertebrate early development. To explore the impacts and underlying mechanisms of PCP on early development, zebrafish (Danio rerio) embryos were exposed to PCP at concentrations of 0, 20 and 50 μg/L, and microscopic observation and cDNA microarray analysis were subsequently conducted at gastrulation stage. The morphological observations revealed that PCP caused a developmental delay of zebrafish embryos in a concentration-dependent manner. Transcriptomic data showed that 50 μg/L PCP treatment resulted in significant changes in gene expression level, and the genes involved in energy metabolism and cell behavior were identified based on gene functional enrichment analysis. The energy production of embryos was influenced by PCP via the activation of glycolysis along with the inhibition of oxidative phosphorylation (OXPHOS). The results suggested that PCP acts as an inhibitor of OXPHOS at 8 hpf (hours postfertilization). Consistent with the activated glycolysis, the cell cycle activity of PCP-treated embryos was higher than the controls. These characteristics are similar to the Warburg effect, which occurs in human tumors. The microinjection of exogenous ATP confirmed that an additional energy supply could rescue PCP-treated embryos from the developmental delay due to the energy deficit. Taken together, our results demonstrated that PCP causes a Warburg-like effect on zebrafish embryos during gastrulation, and the affected embryos had the phenotype of developmental delay. - Highlights: • We treat zebrafish embryos with PCP at gastrula stage. • PCP acts as an oxidative phosphorylation inhibitor, not an uncoupler, in gastrulation. • Exogenous ATP injection will rescue the development of effected embryos. • The transcriptome of PCP
Simulating QCD at the physical point with Nf=2 Wilson twisted mass fermions at maximal twist
International Nuclear Information System (INIS)
Abdel-Rehim, A.; Alexandrou, C.; Cyprus Univ. Nicosia; Burger, F.
2015-12-01
We present simulations of QCD using N f =2 dynamical Wilson twisted mass lattice QCD with physical value of the pion mass and at one value of the lattice spacing. Such simulations at a∼0.09 fm became possible by adding the clover term to the action. While O(a) improvement is still guaranteed by Wilson twisted mass fermions at maximal twist, the introduction of the clover term reduces O(a 2 ) cutoff effects related to isospin symmetry breaking. We give results for a set of phenomenologically interesting observables like pseudo-scalar masses and decay constants, quark masses and the anomalous magnetic moments of leptons. We mostly find remarkably good agreement with phenomenology, even though we cannot take the continuum and thermodynamic limits.
Teaching Spatial Awareness for Better Twisting Somersaults.
Hennessy, Jeff T.
1985-01-01
The barani (front somersault with one-half twist) and the back somersault with one twist are basic foundation skills necessary for more advanced twisting maneuvers. Descriptions of these movements on a trampoline surface are offered. (DF)
Spinning geometry = Twisted geometry
International Nuclear Information System (INIS)
Freidel, Laurent; Ziprick, Jonathan
2014-01-01
It is well known that the SU(2)-gauge invariant phase space of loop gravity can be represented in terms of twisted geometries. These are piecewise-linear-flat geometries obtained by gluing together polyhedra, but the resulting geometries are not continuous across the faces. Here we show that this phase space can also be represented by continuous, piecewise-flat three-geometries called spinning geometries. These are composed of metric-flat three-cells glued together consistently. The geometry of each cell and the manner in which they are glued is compatible with the choice of fluxes and holonomies. We first remark that the fluxes provide each edge with an angular momentum. By studying the piecewise-flat geometries which minimize edge lengths, we show that these angular momenta can be literally interpreted as the spin of the edges: the geometries of all edges are necessarily helices. We also show that the compatibility of the gluing maps with the holonomy data results in the same conclusion. This shows that a spinning geometry represents a way to glue together the three-cells of a twisted geometry to form a continuous geometry which represents a point in the loop gravity phase space. (paper)
DEFF Research Database (Denmark)
Randrup, Thomas; Røgen, Peter
1997-01-01
is an invariant of ambient isotopy measuring the topological twist of the closed strip. We classify closed strips in euclidean 3-space by their knots and their twisting number. We prove that this classification exactly divides closed strips into isotopy classes. Using this classification we point out how some...
Directory of Open Access Journals (Sweden)
Marion Coolen
Full Text Available Due to the presence of a blastopore as in amphibians, the turtle has been suggested to exemplify a transition form from an amphibian- to an avian-type gastrulation pattern. In order to test this hypothesis and gain insight into the emergence of the unique characteristics of amniotes during gastrulation, we have performed the first molecular characterization of the gastrula in a reptile, the turtle Emys orbicularis. The study of Brachyury, Lim1, Otx2 and Otx5 expression patterns points to a highly conserved dynamic of expression with amniote model organisms and makes it possible to identify the site of mesoderm internalization, which is a long-standing issue in reptiles. Analysis of Brachyury expression also highlights the presence of two distinct phases, less easily recognizable in model organisms and respectively characterized by an early ring-shaped and a later bilateral symmetrical territory. Systematic comparisons with tetrapod model organisms lead to new insights into the relationships of the blastopore/blastoporal plate system shared by all reptiles, with the blastopore of amphibians and the primitive streak of birds and mammals. The biphasic Brachyury expression pattern is also consistent with recent models of emergence of bilateral symmetry, which raises the question of its evolutionary significance.
Higher-Twist Dynamics in Large Transverse Momentum Hadron Production
International Nuclear Information System (INIS)
Francois, Alero
2009-01-01
A scaling law analysis of the world data on inclusive large-p # perpendicular# hadron production in hadronic collisions is carried out. A significant deviation from leading-twist perturbative QCD predictions at next-to-leading order is reported. The observed discrepancy is largest at high values of x # perpendicular# = 2p # perpendicular#/√s. In contrast, the production of prompt photons and jets exhibits the scaling behavior which is close to the conformal limit, in agreement with the leading-twist expectation. These results bring evidence for a non-negligible contribution of higher-twist processes in large-p # perpendicular# hadron production in hadronic collisions, where the hadron is produced directly in the hard subprocess rather than by gluon or quark jet fragmentation. Predictions for scaling exponents at RHIC and LHC are given, and it is suggested to trigger the isolated large-p # perpendicular# hadron production to enhance higher-twist processes.
Dohn, Michael R; Mundell, Nathan A; Sawyer, Leah M; Dunlap, Julie A; Jessen, Jason R
2013-11-01
Zebrafish gastrulation cell movements occur in the context of dynamic changes in extracellular matrix (ECM) organization and require the concerted action of planar cell polarity (PCP) proteins that regulate cell elongation and mediolateral alignment. Data obtained using Xenopus laevis gastrulae have shown that integrin-fibronectin interactions underlie the formation of polarized cell protrusions necessary for PCP and have implicated PCP proteins themselves as regulators of ECM. By contrast, the relationship between establishment of PCP and ECM assembly/remodeling during zebrafish gastrulation is unclear. We previously showed that zebrafish embryos carrying a null mutation in the four-pass transmembrane PCP protein vang-like 2 (vangl2) exhibit increased matrix metalloproteinase activity and decreased immunolabeling of fibronectin. These data implicated for the first time a core PCP protein in the regulation of pericellular proteolysis of ECM substrates and raised the question of whether other zebrafish PCP proteins also impact ECM organization. In Drosophila melanogaster, the cytoplasmic PCP protein Prickle binds Van Gogh and regulates its function. Here we report that similar to vangl2, loss of zebrafish prickle1a decreases fibronectin protein levels in gastrula embryos. We further show that Prickle1a physically binds Vangl2 and regulates both the subcellular distribution and total protein level of Vangl2. These data suggest that the ability of Prickle1a to impact fibronectin organization is at least partly due to effects on Vangl2. In contrast to loss of either Vangl2 or Prickle1a function, we find that glypican4 (a Wnt co-receptor) and frizzled7 mutant gastrula embryos with disrupted non-canonical Wnt signaling exhibit the opposite phenotype, namely increased fibronectin assembly. Our data show that glypican4 mutants do not have decreased proteolysis of ECM substrates, but instead have increased cell surface cadherin protein expression and increased intercellular
Tanaka, Tetsuya S; Ikenishi, Kohji
2002-02-01
An acidic, 38 kDa protein that is present in Xenopus wild-type embryos has been previously shown to be lacking in gastrula-arrested mutant embryos. To gain understanding of the role of this protein, its spatio-temporal distribution and involvement in gastrulation was investigated using the monoclonal antibody (9D10) against it. The protein was prominent in the cortical cytoplasm of cells facing the outside in the animal hemisphere of embryos until the gastrula stage, and in ciliated epithelial cells of embryos at stages later than the late neurula. When the 9D10 antibody was injected into fertilized wild-type eggs, they cleaved normally, but most of them had arrested development, always at the early stage of gastrulation, as in the mutant embryos. In contrast, the majority of the control antibody-injected eggs gastrulated normally and developed further. Cytoskeletal F-actin, which was mainly observed in the area beneath the plasma membrane facing the outside of the epithelial layer of not only the dorsal involuting marginal zone but also the dorsal, vegetal cell mass of the control antibody-injected embryos at the early gastrula stage, was scarcely recognized in the corresponding area of the 9D10 antibody-injected embryos. It is likely that the paucity of the F-actin caused by the 9D10 antibody inhibition of the 38 kDa protein might lead to a failure of cell movement in gastrulation, resulting in developmental arrest.
Partial twisting for scalar mesons
International Nuclear Information System (INIS)
Agadjanov, Dimitri; Meißner, Ulf-G.; Rusetsky, Akaki
2014-01-01
The possibility of imposing partially twisted boundary conditions is investigated for the scalar sector of lattice QCD. According to the commonly shared belief, the presence of quark-antiquark annihilation diagrams in the intermediate state generally hinders the use of the partial twisting. Using effective field theory techniques in a finite volume, and studying the scalar sector of QCD with total isospin I=1, we however demonstrate that partial twisting can still be performed, despite the fact that annihilation diagrams are present. The reason for this are delicate cancellations, which emerge due to the graded symmetry in partially quenched QCD with valence, sea and ghost quarks. The modified Lüscher equation in case of partial twisting is given
Emanuelsson, H; Heby, O
1978-01-01
Development eggs of the polychete Ophryotrocha labronica were analyzed for polyamines during the first 6 days after fertilization. The spermine content dominated initially, but gradually decreased. It was surpassed by putrescine, which rapidly increased to a maximum on the 3rd day, i.e., at the inception of grastrulation. The spermidine content was low during the entire period. Treatment of eggs with the putrescine synthesis inhibitor alpha-methylornithine from the onset of development led to developmental arrest at gastrulation and to an abnormally low content of putrescine in the treated embryos. Methylglyoxal bis(guanylhydrazone), an inhibitor of spermine and spermidine synthesis, had no visible effect of development. Our observations strongly suggest that putrescine synthesis is indispensable in early embryonic development of Ophryotrocha. Images PMID:273215
DEFF Research Database (Denmark)
Vejlsted, Morten; Offenberg, Hanne Kjær; Thorup, Flemming
2006-01-01
was selectively observed in the epiblast. A prominent crescent-shaped thickening at the posterior region of the embryonic disk marked the first polarization within this structure reflecting incipient cell ingression. Following differentiation of the epiblast, clearance of OCT4 from the three germ layers......In the areas of developmental biology and embryonic stem cell research, reliable molecular markers of pluripotency and early lineage commitment are sparse in large animal species. In this study, we present morphological and immunohistochemical findings on the porcine embryo in the period around...... gastrulation, days 8-17 postinsemination, introducing a steromicroscopical staging system in this species. In embryos at the expanding hatched blastocyst stage, OCT4 is confined to the inner cell mass. Following detachment of the hypoblast, and formation of the embryonic disk, this marker of pluripotency...
Observations on discretization errors in twisted-mass lattice QCD
International Nuclear Information System (INIS)
Sharpe, Stephen R.
2005-01-01
I make a number of observations concerning discretization errors in twisted-mass lattice QCD that can be deduced by applying chiral perturbation theory including lattice artifacts. (1) The line along which the partially conserved axial current quark mass vanishes in the untwisted-mass-twisted-mass plane makes an angle to the twisted-mass axis which is a direct measure of O(a) terms in the chiral Lagrangian, and is found numerically to be large; (2) Numerical results for pionic quantities in the mass plane show the qualitative properties predicted by chiral perturbation theory, in particular, an asymmetry in slopes between positive and negative untwisted quark masses; (3) By extending the description of the 'Aoki regime' (where m q ∼a 2 Λ QCD 3 ) to next-to-leading order in chiral perturbation theory I show how the phase-transition lines and lines of maximal twist (using different definitions) extend into this region, and give predictions for the functional form of pionic quantities; (4) I argue that the recent claim that lattice artifacts at maximal twist have apparent infrared singularities in the chiral limit results from expanding about the incorrect vacuum state. Shifting to the correct vacuum (as can be done using chiral perturbation theory) the apparent singularities are summed into nonsingular, and furthermore predicted, forms. I further argue that there is no breakdown in the Symanzik expansion in powers of lattice spacing, and no barrier to simulating at maximal twist in the Aoki regime
Photophysics of internal twisting
International Nuclear Information System (INIS)
Heisel, F.; Miehe, J.A.; Lippert, E.; Rettig, W.; Bonacic-Koutecky, V.
1987-01-01
The formation and characteristics of the ''twisted intermolecular charge transfer'' is studied. Basic concepts on dual fluorescence, steady-state fluorescence, kinetic investigations and cage effects are discussed. The theoretical treatment on the electronic structure of the bonded π - donor - π acceptor pairs is outlined. The two-electron, two-orbital model, the ab initio CI models of simple double, charged and dative π - bonds as well as complex dative π - bonds and the origin of the dual fluorescence of 9.9'-Bianthryl are shown. Concerning the stochastic description of chemical reactions, Master equation, Markov, Birth-Death and Diffusion processes, Kramers-Moyal expansion, Langevin equation, Kramers' approach to steady-state rates of reaction and its extension to non-Markovian processes, and also unimolecular reactions in the absence of potential barrier are considered. Experimental results and interpretation on dynamics of DMABN in the excited state, kinetics of other dialkylanilines, extended donor-acceptor systems with anomalous fluorescence and donor-acceptor systems without anomalous fluorescence are given
Casali, Eduardo; Tourkine, Piotr
2018-03-01
Twistor string models have been known for more than a decade now but have come back under the spotlight recently with the advent of the scattering equation formalism which has greatly generalized the scope of these models. A striking ubiquitous feature of these models has always been that, contrary to usual string theory, they do not admit vibrational modes and thus describe only conventional field theory. In this paper we report on the surprising discovery of a whole new sector of one of these theories which we call "twisted strings," when spacetime has compact directions. We find that the spectrum is enhanced from a finite number of states to an infinite number of interacting higher spin massive states. We describe both bosonic and world sheet supersymmetric models, their spectra and scattering amplitudes. These models have distinctive features of both string and field theory, for example they are invariant under stringy T-duality but have the high energy behavior typical of field theory. Therefore they describe a new kind of field theories in target space, sitting on their own halfway between string and field theory.
Design optimization for active twist rotor blades
Mok, Ji Won
This dissertation introduces the process of optimizing active twist rotor blades in the presence of embedded anisotropic piezo-composite actuators. Optimum design of active twist blades is a complex task, since it involves a rich design space with tightly coupled design variables. The study presents the development of an optimization framework for active helicopter rotor blade cross-sectional design. This optimization framework allows for exploring a rich and highly nonlinear design space in order to optimize the active twist rotor blades. Different analytical components are combined in the framework: cross-sectional analysis (UM/VABS), an automated mesh generator, a beam solver (DYMORE), a three-dimensional local strain recovery module, and a gradient based optimizer within MATLAB. Through the mathematical optimization problem, the static twist actuation performance of a blade is maximized while satisfying a series of blade constraints. These constraints are associated with locations of the center of gravity and elastic axis, blade mass per unit span, fundamental rotating blade frequencies, and the blade strength based on local three-dimensional strain fields under worst loading conditions. Through pre-processing, limitations of the proposed process have been studied. When limitations were detected, resolution strategies were proposed. These include mesh overlapping, element distortion, trailing edge tab modeling, electrode modeling and foam implementation of the mesh generator, and the initial point sensibility of the current optimization scheme. Examples demonstrate the effectiveness of this process. Optimization studies were performed on the NASA/Army/MIT ATR blade case. Even though that design was built and shown significant impact in vibration reduction, the proposed optimization process showed that the design could be improved significantly. The second example, based on a model scale of the AH-64D Apache blade, emphasized the capability of this framework to
International Nuclear Information System (INIS)
Ketov, S.V.; Lechtenfeld, O.; Parkes, A.J.
1993-12-01
The most general homogeneous monodromy conditions in N= 2 string theory are classified in terms of the conjugacy classes of the global symmetry group U(1, 1) x Z 2 . For classes which generate a discrete subgroup Γ, the corresponding target space backgrounds C 1,1 /Γ include half spaces, complex orbifolds and tori. We propose a generalization of the intercept formula to matrix-valued twists, and find massless physical states in a number of twisted cases. In particular, the sixteen Z 2 -twisted sectors of the N = 2 string are investigated, and the corresponding ground states are identified via bosonization and BRST cohomology. We find enough room for an extended multiplet of 'spacetime' supersymmetry, with the number of supersymmetries being dependent on global 'spacetime' topology. Unfortunately, world-sheet locality for the chiral vertex operators does not permit interactions for the massless 'spacetime' fermions; however possibly, an asymmetric GSO projection could evade this problem. (orig.)
Introduction to twisted conformal fields
International Nuclear Information System (INIS)
Kazama, Y.
1988-01-01
A pedagogical account is given of the recent developments in the theory of twisted conformal fields. Among other things, the main part of the lecture concerns the construction of the twist-emission vertex operator, which is a generalization of the fermion emission vertex in the superstring theory. Several different forms of the vertex are derived and their mutural relationships are clarified. In this paper, the authors include a brief survey of the history of the fermion emission vertex, as it offers a good perspective in which to appreciate the logical development
Hardy, Katharine M.; Garriock, Robert J.; Yatskievych, Tatiana A.; D'Agostino, Susan L.; Antin, Parker B.; Krieg, Paul A.
2008-01-01
Knowledge of the molecular mechanisms regulating cell ingression, epithelial-mesenchymal transition and migration movements during amniote gastrulation is steadily improving. In the frog and fish embryo, Wnt5 and Wnt11 ligands are expressed around the blastopore and play an important role in regulating cell movements associated with gastrulation. In the chicken embryo, although Wnt5a and Wnt5b are expressed in the primitive streak, the known Wnt11 gene is expressed in paraxial and intermediat...
Kreiling, Jill A; Balantac, Zaneta L; Crawford, Andrew R; Ren, Yuexin; Toure, Jamal; Zchut, Sigalit; Kochilas, Lazaros; Creton, Robbert
2008-01-01
Vertebrate embryos generate striking Ca(2+) patterns, which are unique regulators of dynamic developmental events. In the present study, we used zebrafish embryos as a model system to examine the developmental roles of Ca(2+) during gastrulation. We found that gastrula stage embryos maintain a distinct pattern of cytosolic Ca(2+) along the dorsal-ventral axis, with higher Ca(2+) concentrations in the ventral margin and lower Ca(2+) concentrations in the dorsal margin and dorsal forerunner cells. Suppression of the endoplasmic reticulum Ca(2+) pump with 0.5 microM thapsigargin elevates cytosolic Ca(2+) in all embryonic regions and induces a randomization of laterality in the heart and brain. Affected hearts, visualized in living embryos by a subtractive imaging technique, displayed either a reversal or loss of left-right asymmetry. Brain defects include a left-right reversal of pitx2 expression in the dorsal diencephalon and a left-right reversal of the prominent habenular nucleus in the brain. Embryos are sensitive to inhibition of the endoplasmic reticulum Ca(2+) pump during early and mid gastrulation and lose their sensitivity during late gastrulation and early segmentation. Suppression of the endoplasmic reticulum Ca(2+) pump during gastrulation inhibits expression of no tail (ntl) and left-right dynein related (lrdr) in the dorsal forerunner cells and affects development of Kupffer's vesicle, a ciliated organ that generates a counter-clockwise flow of fluid. Previous studies have shown that Ca(2+) plays a role in Kupffer's vesicle function, influencing ciliary motility and translating the vesicle's counter-clockwise flow into asymmetric patterns of gene expression. The present results suggest that Ca(2+) plays an additional role in the formation of Kupffer's vesicle.
Hara, Yusuke; Nagayama, Kazuaki; Yamamoto, Takamasa S; Matsumoto, Takeo; Suzuki, Makoto; Ueno, Naoto
2013-10-15
Gastrulation is a dynamic tissue-remodeling process occurring during early development and fundamental to the later organogenesis. It involves both chemical signals and physical factors. Although much is known about the molecular pathways involved, the roles of physical forces in regulating cellular behavior and tissue remodeling during gastrulation have just begun to be explored. Here, we characterized the force generated by the leading edge mesoderm (LEM) that migrates preceding axial mesoderm (AM), and investigated the contribution of LEM during Xenopus gastrulation. First, we constructed an assay system using micro-needle which could measure physical forces generated by the anterior migration of LEM, and estimated the absolute magnitude of the force to be 20-80nN. Second, laser ablation experiments showed that LEM could affect the force distribution in the AM (i.e. LEM adds stretch force on axial mesoderm along anterior-posterior axis). Third, migrating LEM was found to be necessary for the proper gastrulation cell movements and the establishment of organized notochord structure; a reduction of LEM migratory activity resulted in the disruption of mediolateral cell orientation and convergence in AM. Finally, we found that LEM migration cooperates with Wnt/PCP to form proper notochord. These results suggest that the force generated by the directional migration of LEM is transmitted to AM and assists the tissue organization of notochord in vivo independently of the regulation by Wnt/PCP. We propose that the LEM may have a mechanical role in aiding the AM elongation through the rearrangement of force distribution in the dorsal marginal zone. © 2013 Elsevier Inc. All rights reserved.
Waveguides with asymptotically diverging twisting
Czech Academy of Sciences Publication Activity Database
Krejčiřík, David
2015-01-01
Roč. 46, AUG (2015), s. 7-10 ISSN 0893-9659 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : quantum waveguide * exploding twisting * Quasi-bounded * Quasi-cylindrical * discrete spectrum Subject RIV: BE - Theoretical Physics Impact factor: 1.659, year: 2015
Obstructions for twist star products
Bieliavsky, Pierre; Esposito, Chiara; Waldmann, Stefan; Weber, Thomas
2018-05-01
In this short note, we point out that not every star product is induced by a Drinfel'd twist by showing that not every Poisson structure is induced by a classical r-matrix. Examples include the higher genus symplectic Pretzel surfaces and the symplectic sphere S^2.
Geometry and mechanics of teleost gastrulation and the formation of primary embryonic axes.
Cherdantseva, Elena M; Cherdantsev, Vladimir G
2006-01-01
Examination of normal shaping dynamics and immediate and long-term responses to blastoderm cutting in zebrafish and loach embryos prior to the onset of gastrulation and during the course of epiboly revealed that anteroposterior (AP) and dorsoventral (DV) polarity formation is connected with shaping of the blastoderm circumferential region, which stretches along and shrinks across its movement axes and originates the non-isotropic fields of tensile stresses. Based on data from cutting experiments and quantitative morphology, we reconstructed the movement-shaping patterns of epiboly and embryonic shield formation. We revealed that AP and DV axes originate as a mass cell movement subject to the movement-shaping equivalence principle, which means the spatial series of differently shaped areas corresponding to the time succession of the same area shaping. Maintenance of the main body axes in orthogonal orientation depends on the mechanical equilibrium principle allowing for converting shape asymmetry into that of tensile stresses and vice versa. The causal relationship between the main movement-shaping axes and that of embryonic polarity was proved in cutting experiments in which the DV axis direction was subject to rearrangement so as to adjust to the new direction of mass cell movement axes induced by healing the wound in the blastoderm circumferential region.
Directory of Open Access Journals (Sweden)
Hisham Mohammed
2017-08-01
Full Text Available The mouse inner cell mass (ICM segregates into the epiblast and primitive endoderm (PrE lineages coincident with implantation of the embryo. The epiblast subsequently undergoes considerable expansion of cell numbers prior to gastrulation. To investigate underlying regulatory principles, we performed systematic single-cell RNA sequencing (seq of conceptuses from E3.5 to E6.5. The epiblast shows reactivation and subsequent inactivation of the X chromosome, with Zfp57 expression associated with reactivation and inactivation together with other candidate regulators. At E6.5, the transition from epiblast to primitive streak is linked with decreased expression of polycomb subunits, suggesting a key regulatory role. Notably, our analyses suggest elevated transcriptional noise at E3.5 and within the non-committed epiblast at E6.5, coinciding with exit from pluripotency. By contrast, E6.5 primitive streak cells became highly synchronized and exhibit a shortened G1 cell-cycle phase, consistent with accelerated proliferation. Our study systematically charts transcriptional noise and uncovers molecular processes associated with early lineage decisions.
Borel resummation of soft gluon radiation and higher twists
International Nuclear Information System (INIS)
Forte, Stefano; Ridolfi, Giovanni; Rojo, Joan; Ubiali, Maria
2006-01-01
We show that the well-known divergence of the perturbative expansion of resummed results for processes such as deep-inelastic scattering and Drell-Yan in the soft limit can be treated by Borel resummation. The divergence in the Borel inversion can be removed by the inclusion of suitable higher twist terms. This provides us with an alternative to the standard 'minimal prescription' for the asymptotic summation of the perturbative expansion, and it gives us some handle on the role of higher twist corrections in the soft resummation region
Stability of short wavelength tearing and twisting modes
International Nuclear Information System (INIS)
Waelbroeck, F.L.
1998-01-01
The stability and mutual interaction of tearing and twisting modes in a torus is governed by matrices that generalize the well-known Δ' stability index. The diagonal elements of these matrices determine the intrinsic stability of modes that reconnect the magnetic field at a single resonant surface. The off-diagonal elements indicate the strength of the coupling between the different modes. The author shows how the elements of these matrices can be evaluated, in the limit of short wavelength, from the free energy driving radially extended ballooning modes. The author applies the results by calculating the tearing and twisting Δ' for a model high-beta equilibrium with circular flux surfaces
Twist deformations of the supersymmetric quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Castro, P.G.; Chakraborty, B.; Toppan, F., E-mail: pgcastro@cbpf.b, E-mail: biswajit@bose.res.i, E-mail: toppan@cbpf.b [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Kuznetsova, Z., E-mail: zhanna.kuznetsova@ufabc.edu.b [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)
2009-07-01
The N-extended supersymmetric quantum mechanics is deformed via an abelian twist which preserves the super-Hopf algebra structure of its universal enveloping superalgebra. Two constructions are possible. For even N one can identify the 1D N-extended superalgebra with the fermionic Heisenberg algebra. Alternatively, supersymmetry generators can be realized as operators belonging to the Universal Enveloping Superalgebra of one bosonic and several fermionic oscillators. The deformed system is described in terms of twisted operators satisfying twist deformed (anti)commutators. The main differences between an abelian twist defined in terms of fermionic operators and an abelian twist defined in terms of bosonic operators are discussed. (author)
Noncommutative geometry and twisted conformal symmetry
International Nuclear Information System (INIS)
Matlock, Peter
2005-01-01
The twist-deformed conformal algebra is constructed as a Hopf algebra with twisted coproduct. This allows for the definition of conformal symmetry in a noncommutative background geometry. The twisted coproduct is reviewed for the Poincare algebra and the construction is then extended to the full conformal algebra. The case of Moyal-type noncommutativity of the coordinates is considered. It is demonstrated that conformal invariance need not be viewed as incompatible with noncommutative geometry; the noncommutativity of the coordinates appears as a consequence of the twisting, as has been shown in the literature in the case of the twisted Poincare algebra
Modal properties and stability of bend–twist coupled wind turbine blades
Directory of Open Access Journals (Sweden)
A. R. Stäblein
2017-06-01
Full Text Available Coupling between bending and twist has a significant influence on the aeroelastic response of wind turbine blades. The coupling can arise from the blade geometry (e.g. sweep, prebending, or deflection under load or from the anisotropic properties of the blade material. Bend–twist coupling can be utilized to reduce the fatigue loads of wind turbine blades. In this study the effects of material-based coupling on the aeroelastic modal properties and stability limits of the DTU 10 MW Reference Wind Turbine are investigated. The modal properties are determined by means of eigenvalue analysis around a steady-state equilibrium using the aero-servo-elastic tool HAWCStab2 which has been extended by a beam element that allows for fully coupled cross-sectional properties. Bend–twist coupling is introduced in the cross-sectional stiffness matrix by means of coupling coefficients that introduce twist for flapwise (flap–twist coupling or edgewise (edge–twist coupling bending. Edge–twist coupling can increase or decrease the damping of the edgewise mode relative to the reference blade, depending on the operational condition of the turbine. Edge–twist to feather coupling for edgewise deflection towards the leading edge reduces the inflow speed at which the blade becomes unstable. Flap–twist to feather coupling for flapwise deflections towards the suction side increase the frequency and reduce damping of the flapwise mode. Flap–twist to stall reduces frequency and increases damping. The reduction of blade root flapwise and tower bottom fore–aft moments due to variations in mean wind speed of a flap–twist to feather blade are confirmed by frequency response functions.
Renormalization constants for 2-twist operators in twisted mass QCD
International Nuclear Information System (INIS)
Alexandrou, C.; Constantinou, M.; Panagopoulos, H.; Stylianou, F.; Korzec, T.
2011-01-01
Perturbative and nonperturbative results on the renormalization constants of the fermion field and the twist-2 fermion bilinears are presented with emphasis on the nonperturbative evaluation of the one-derivative twist-2 vector and axial-vector operators. Nonperturbative results are obtained using the twisted mass Wilson fermion formulation employing two degenerate dynamical quarks and the tree-level Symanzik improved gluon action. The simulations have been performed for pion masses in the range of about 450-260 MeV and at three values of the lattice spacing a corresponding to β=3.9, 4.05, 4.20. Subtraction of O(a 2 ) terms is carried out by performing the perturbative evaluation of these operators at 1-loop and up to O(a 2 ). The renormalization conditions are defined in the RI ' -MOM scheme, for both perturbative and nonperturbative results. The renormalization factors, obtained for different values of the renormalization scale, are evolved perturbatively to a reference scale set by the inverse of the lattice spacing. In addition, they are translated to MS at 2 GeV using 3-loop perturbative results for the conversion factors.
Drag Performance of Twist Morphing MAV Wing
Directory of Open Access Journals (Sweden)
Ismail N.I.
2016-01-01
Full Text Available Morphing wing is one of latest evolution found on MAV wing. However, due to few design problems such as limited MAV wing size and complicated morphing mechanism, the understanding of its aerodynamic behaviour was not fully explored. In fact, the basic drag distribution induced by a morphing MAV wing is still remained unknown. Thus, present work is carried out to compare the drag performance between a twist morphing wing with membrane and rigid MAV wing design. A quasi-static aeroelastic analysis by using the Ansys-Fluid Structure Interaction (FSI method is utilized in current works to predict the drag performance a twist morphing MAV wing design. Based on the drag pattern study, the results exhibits that the morphing wing has a partial similarities in overall drag pattern with the baseline (membrane and rigid wing. However, based CD analysis, it shows that TM wing induced higher CD magnitude (between 25% to 82% higher than to the baseline wing. In fact, TM wing also induced the largest CD increment (about 20% to 27% among the wings. The visualization on vortex structure revealed that TM wing also produce larger tip vortex structure (compared to baseline wings which presume to promote higher induce drag component and subsequently induce its higher CD performance.
Effective potentials for twisted fields
International Nuclear Information System (INIS)
Banach, R.
1981-01-01
Minus the density of the effective action, evaluated at the lowest eigenfunction of the (space-time) derivative part of the second (functional) derivative of the classical action, is proposed as a generalised definition of the effective potential, applicable to twisted as well as untwisted sectors of a field theory. The proposal is corroborated by several specific calculations in the twisted sector, namely phi 4 theory (real and complex) and wrong-sign-Gordon theory, in an Einstein cylinder, where the exact integrability of the static solutions confirms the effective potential predictions. Both models exhibit a phase transition, which the effective potential locates, and the one-loop quantum shift in the critical radius is computed for the real phi 4 model, being a universal result. Topological mass generation at the classical level is pointed out, and the exactness of the classical effective potential approximation for complex phi 4 is discussed. (author)
Twisting formula of epsilon factors
Indian Academy of Sciences (India)
Sazzad Ali Biswas
2017-08-07
Aug 7, 2017 ... In this article, we give a generalized twisting formula for ϵ(χ1χ2,ψ), when both χ1 and χ2 are ramified via the following local Jacobi sums. Let UF be the group of units in OF (ring of integers of F). For characters χ1, χ2 of F. × and a positive integer n, we define the local Jacobi sum. Jt(χ1,χ2, n) = ∑ x∈UF. Un.
Modeling and control of active twist aircraft
Cramer, Nicholas Bryan
The Wright Brothers marked the beginning of powered flight in 1903 using an active twist mechanism as their means of controlling roll. As time passed due to advances in other technologies that transformed aviation the active twist mechanism was no longer used. With the recent advances in material science and manufacturability, the possibility of the practical use of active twist technologies has emerged. In this dissertation, the advantages and disadvantages of active twist techniques are investigated through the development of an aeroelastic modeling method intended for informing the designs of such technologies and wind tunnel testing to confirm the capabilities of the active twist technologies and validate the model. Control principles for the enabling structural technologies are also proposed while the potential gains of dynamic, active twist are analyzed.
International Nuclear Information System (INIS)
Zhou, Jinyuan; Xie, Erqing; Sun, Gengzhi; Zhan, Zhaoyao; Zheng, Lianxi
2014-01-01
The dependences of twisting parameters on the electric and mechanical properties of twisted CNT fibers were systematically studied. Results from electric and mechanical measurements showed that twisting intensity is very effective to improve the electric and mechanical properties of CNT fibers. Further calculations combined with Raman results indicate that the twisting treatments, to a certain extent, can greatly enhance the strain transfer factors of the samples, which dominates the mechanical properties of CNT fibers. In addition, studies on the effect of twisting speeds suggested that lower twisting speed can lead to higher uniformity but lower performances in the electric and mechanical properties, higher twisting speed to higher Young’s modulus and higher conductance but lower uniformities. Ultra-strong uniform CNT fibers need to be prepared with a suitable twisting speed. (paper)
Remarks on twisted noncommutative quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Zahn, J. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2006-04-15
We review recent results on twisted noncommutative quantum field theory by embedding it into a general framework for the quantization of systems with a twisted symmetry. We discuss commutation relations in this setting and show that the twisted structure is so rigid that it is hard to derive any predictions, unless one gives up general principles of quantum theory. It is also shown that the twisted structure is not responsible for the presence or absence of UV/IR-mixing, as claimed in the literature. (Orig.)
DVCS amplitude with kinematical twist-3 terms
International Nuclear Information System (INIS)
Radyushkin, A.V.; Weiss, C.
2000-01-01
The authors compute the amplitude of deeply virtual Compton scattering (DVCS) using the calculus of QCD string operators in coordinate representation. To restore the electromagnetic gauge invariance (transversality) of the twist-2 amplitude they include the operators of twist-3 which appear as total derivatives of twist-2 operators. The results are equivalent to a Wandzura-Wilczek approximation for twist-3 skewed parton distributions. They find that this approximation gives a finite result for the amplitude of a longitudinally polarized virtual photon, while the amplitude for transverse polarization is divergent, i.e., factorization breaks down in this term
Radiative capture of cold neutrons by protons and deuteron photodisintegration with twisted beams
Afanasev, Andrei; Serbo, Valeriy G.; Solyanik, Maria
2018-05-01
We consider two basic nuclear reactions: capture of neutrons by protons, n + p → γ + d, and its time-reversed counterpart, photodisintegration of the deuteron, γ + d → n + p. In both of these cases we assume that the incoming beam of neutrons or photons is ‘twisted’ by having an azimuthal phase dependence, i.e., it carries an additional angular momentum along its direction of propagation. Taking a low-energy limit of these reactions, we derive relations between corresponding transition amplitudes and cross sections with plane-wave beams and twisted beams. Implications for experiments with twisted cold neutrons and twisted photon beams are discussed.
Device for measuring well twistings
Energy Technology Data Exchange (ETDEWEB)
Kostin, Yu S; Golubin, S V; Keller, V F; Merzheyevskiy, A B; Zdorov, V P
1982-01-01
The device for measuring the well twistings with the use of fluids (poured into a vessel and which leave an imprint on the walls), containing a housing and adapter, is distinguished by the fact that in order to improve the accuracy of measurement by obtaining a clear imprint, it is equipped with cylinder that is spring-loaded in relation to the adapter, forming a vessel for fluid with the adapter. The adapter is made of two parts, one of which is made of neutral metal in relation to the fluid, and the other, from active in relation to the same fluid.
Patterning and gastrulation defects caused by the tw18 lethal are due to loss of Ppp2r1a
Directory of Open Access Journals (Sweden)
Lisette Lange
2017-06-01
Full Text Available The mouse t haplotype, a variant 20 cM genomic region on Chromosome 17, harbors 16 embryonic control genes identified by recessive lethal mutations isolated from wild mouse populations. Due to technical constraints so far only one of these, the tw5 lethal, has been cloned and molecularly characterized. Here we report the molecular isolation of the tw18 lethal. Embryos carrying the tw18 lethal die from major gastrulation defects commencing with primitive streak formation at E6.5. We have used transcriptome and marker gene analyses to describe the molecular etiology of the tw18 phenotype. We show that both WNT and Nodal signal transduction are impaired in the mutant epiblast, causing embryonic patterning defects and failure of primitive streak and mesoderm formation. By using a candidate gene approach, gene knockout by homologous recombination and genetic rescue, we have identified the gene causing the tw18 phenotype as Ppp2r1a, encoding the PP2A scaffolding subunit PR65alpha. Our work highlights the importance of phosphatase 2A in embryonic patterning, primitive streak formation, gastrulation, and mesoderm formation downstream of WNT and Nodal signaling.
Overlap valence quarks on an twisted mass sea
Energy Technology Data Exchange (ETDEWEB)
Cichy, K. [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Drach, V.; Garcia-Ramos, E.; Herdoiza, G.; Jansen, K. [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC
2010-12-15
We present the results of an investigation of a mixed action approach of overlap valence and maximally twisted mass sea quarks. Employing a particular matching condition on the pion mass, we analyze the continuum limit scaling of the pion decay constant and the role of chiral zero modes of the overlap operator in this process. We employ gauge field configurations generated by the European Twisted Mass Collaboration with linear lattice size L ranging from 1.3 to 1.9 fm. The continuum limit is taken at a fixed value of L=1.3 fm, employing three values of the lattice spacing and two values of the pion mass constructed from sea quarks only. (orig.)
Continuous Static Gait with Twisting Trunk of a Metamorphic Quadruped Robot
Directory of Open Access Journals (Sweden)
C. Zhang
2018-01-01
Full Text Available The natural quadrupeds, such as geckos and lizards, often twist their trunks when moving. Conventional quadruped robots cannot perform the same motion due to equipping with a trunk which is a rigid body or at most consists of two blocks connected by passive joints. This paper proposes a metamorphic quadruped robot with a reconfigurable trunk which can implement active trunk motions, called MetaRobot I. The robot can imitate the natural quadrupeds to execute motion of trunk twisting. Benefiting from the twisting trunk, the stride length of this quadruped is increased comparing to that of conventional quadruped robots.In this paper a continuous static gait benefited from the twisting trunk performing the increased stride length is introduced. After that, the increased stride length relative to the trunk twisting will be analysed mathematically. Other points impacting the implementation of the increased stride length in the gait are investigated such as the upper limit of the stride length and the kinematic margin. The increased stride length in the gait will lead the increase of locomotion speed comparing with conventional quadruped robots, giving the extent that natural quadrupeds twisting their trunks when moving. The simulation and an experiment on the prototype are then carried out to illustrate the benefits on the stride length and locomotion speed brought by the twisting trunk to the quadruped robot.
Twist-stretch profiles of DNA chains
Zoli, Marco
2017-06-01
Helical molecules change their twist number under the effect of a mechanical load. We study the twist-stretch relation for a set of short DNA molecules modeled by a mesoscopic Hamiltonian. Finite temperature path integral techniques are applied to generate a large ensemble of possible configurations for the base pairs of the sequence. The model also accounts for the bending and twisting fluctuations between adjacent base pairs along the molecules stack. Simulating a broad range of twisting conformation, we compute the helix structural parameters by averaging over the ensemble of base pairs configurations. The method selects, for any applied force, the average twist angle which minimizes the molecule’s free energy. It is found that the chains generally over-twist under an applied stretching and the over-twisting is physically associated to the contraction of the average helix diameter, i.e. to the damping of the base pair fluctuations. Instead, assuming that the maximum amplitude of the bending fluctuations may decrease against the external load, the DNA molecule first over-twists for weak applied forces and then untwists above a characteristic force value. Our results are discussed in relation to available experimental information albeit for kilo-base long molecules.
International Nuclear Information System (INIS)
Klinkhamer, F.R.
1984-01-01
The recently discovered reduced models of Quantum Chromodynamics in the limit of a large number (N) of colors are discussed, in particular the version that employs appropriate Z(N) twists. Some preliminary numerical data are presented, together with some new analytic results (saddle-points). This may be of some help for understanding the mechanism of confinement, which presumably is the same for all N. Also, the reduced chiral model in two dimensions is discussed
Wilkie, William Keats
1997-12-01
An aeroelastic model suitable for control law and preliminary structural design of composite helicopter rotor blades incorporating embedded anisotropic piezoelectric actuator laminae is developed. The aeroelasticity model consists of a linear, nonuniform beam representation of the blade structure, including linear piezoelectric actuation terms, coupled with a nonlinear, finite-state unsteady aerodynamics model. A Galerkin procedure and numerical integration in the time domain are used to obtain a soluti An aeroelastic model suitable for control law and preliminary structural design of composite helicopter rotor blades incorporating embedded anisotropic piezoelectric actuator laminae is developed. The aeroelasticity model consists of a linear, nonuniform beam representation of the blade structure, including linear piezoelectric actuation terms, coupled with a nonlinear, finite-state unsteady aerodynamics model. A Galerkin procedure and numerical integration in the time domain are used to obtain amited additional piezoelectric material mass, it is shown that blade twist actuation approaches which exploit in-plane piezoelectric free-stain anisotropies are capable of producing amplitudes of oscillatory blade twisting sufficient for rotor vibration reduction applications. The second study examines the effectiveness of using embedded piezoelectric actuator laminae to alleviate vibratory loads due to retreating blade stall. A 10 to 15 percent improvement in dynamic stall limited forward flight speed, and a 5 percent improvement in stall limited rotor thrust were numerically demonstrated for the active twist rotor blade relative to a conventional blade design. The active twist blades are also demonstrated to be more susceptible than the conventional blades to dynamic stall induced vibratory loads when not operating with twist actuation. This is the result of designing the active twist blades with low torsional stiffness in order to maximize piezoelectric twist authority
Quantisation of monotonic twist maps
International Nuclear Information System (INIS)
Boasman, P.A.; Smilansky, U.
1993-08-01
Using an approach suggested by Moser, classical Hamiltonians are generated that provide an interpolating flow to the stroboscopic motion of maps with a monotonic twist condition. The quantum properties of these Hamiltonians are then studied in analogy with recent work on the semiclassical quantization of systems based on Poincare surfaces of section. For the generalized standard map, the correspondence with the usual classical and quantum results is shown, and the advantages of the quantum Moser Hamiltonian demonstrated. The same approach is then applied to the free motion of a particle on a 2-torus, and to the circle billiard. A natural quantization condition based on the eigenphases of the unitary time--development operator is applied, leaving the exact eigenvalues of the torus, but only the semiclassical eigenvalues for the billiard; an explanation for this failure is proposed. It is also seen how iterating the classical map commutes with the quantization. (authors)
Napiorkowski, Maciej; Urbanczyk, Waclaw
2018-04-30
We show that in twisted microstructured optical fibers (MOFs) the coupling between the core and cladding modes can be obtained for helix pitch much greater than previously considered. We provide an analytical model describing scaling properties of the twisted MOFs, which relates coupling conditions to dimensionless ratios between the wavelength, the lattice pitch and the helix pitch of the twisted fiber. Furthermore, we verify our model using a rigorous numerical method based on the transformation optics formalism and study its limitations. The obtained results show that for appropriately designed twisted MOFs, distinct, high loss resonance peaks can be obtained in a broad wavelength range already for the fiber with 9 mm helix pitch, thus allowing for fabrication of coupling based devices using a less demanding method involving preform spinning.
Helicity conservation and twisted Seifert surfaces for superfluid vortices.
Salman, Hayder
2017-04-01
Starting from the continuum definition of helicity, we derive from first principles its different contributions for superfluid vortices. Our analysis shows that an internal twist contribution emerges naturally from the mathematical derivation. This reveals that the spanwise vector that is used to characterize the twist contribution must point in the direction of a surface of constant velocity potential. An immediate consequence of the Seifert framing is that the continuum definition of helicity for a superfluid is trivially zero at all times. It follows that the Gauss-linking number is a more appropriate definition of helicity for superfluids. Despite this, we explain how a quasi-classical limit can arise in a superfluid in which the continuum definition for helicity can be used. This provides a clear connection between a microscopic and a macroscopic description of a superfluid as provided by the Hall-Vinen-Bekarevich-Khalatnikov equations. This leads to consistency with the definition of helicity used for classical vortices.
BK-parameter from Nf=2 twisted mass lattice QCD
International Nuclear Information System (INIS)
Constantinou, M.; Dimopoulos, P.; Frezzotti, R.; INFN, Rome
2011-01-01
We present an unquenched N f = 2 lattice computation of the B K parameter which controls K 0 - anti K 0 oscillations. A partially quenched setup is employed with two maximally twisted dynamical (sea) light Wilson quarks, and valence quarks of both the maximally twisted and the Osterwalder-Seiler variety. Suitable combinations of these two kinds of valence quarks lead to a lattice definition of the B K parameter which is both multiplicatively renormalizable and O(a) improved. Employing the non-perturbative RI-MOM scheme, in the continuum limit and at the physical value of the pion mass we get B RGI K =0.729±0.030, a number well in line with the existing quenched and unquenched determinations. (orig.)
Partially coherent twisted states in arrays of coupled phase oscillators
Energy Technology Data Exchange (ETDEWEB)
Omel' chenko, Oleh E.; Wolfrum, Matthias [Weierstrass Institute, Mohrenstrasse 39, 10117 Berlin (Germany); Laing, Carlo R. [INMS, Massey University, Private Bag 102-904 NSMC, Auckland (New Zealand)
2014-06-15
We consider a one-dimensional array of phase oscillators with non-local coupling and a Lorentzian distribution of natural frequencies. The primary objects of interest are partially coherent states that are uniformly “twisted” in space. To analyze these, we take the continuum limit, perform an Ott/Antonsen reduction, integrate over the natural frequencies, and study the resulting spatio-temporal system on an unbounded domain. We show that these twisted states and their stability can be calculated explicitly. We find that stable twisted states with different wave numbers appear for increasing coupling strength in the well-known Eckhaus scenario. Simulations of finite arrays of oscillators show good agreement with results of the analysis of the infinite system.
Partially coherent twisted states in arrays of coupled phase oscillators
International Nuclear Information System (INIS)
Omel'chenko, Oleh E.; Wolfrum, Matthias; Laing, Carlo R.
2014-01-01
We consider a one-dimensional array of phase oscillators with non-local coupling and a Lorentzian distribution of natural frequencies. The primary objects of interest are partially coherent states that are uniformly “twisted” in space. To analyze these, we take the continuum limit, perform an Ott/Antonsen reduction, integrate over the natural frequencies, and study the resulting spatio-temporal system on an unbounded domain. We show that these twisted states and their stability can be calculated explicitly. We find that stable twisted states with different wave numbers appear for increasing coupling strength in the well-known Eckhaus scenario. Simulations of finite arrays of oscillators show good agreement with results of the analysis of the infinite system
Stability of Medium-Bridged Twisted Amides in Aqueous Solutions
Szostak, Michal; Yao, Lei; Aubé, Jeffrey
2012-01-01
“Twisted” amides containing non-standard dihedral angles are typically hypersensitive to hydrolysis, a feature that has stringently limited their utility in water. We have synthesized a series of bridged lactams that contain a twisted amide linkage but which exhibit enhanced stability in aqueous environments. Many of these compounds were extracted unchanged from aqueous mixtures ranging from the strongly basic to the strongly acidic. NMR experiments showed that tricyclic lactams undergo reversible hydrolysis at extreme pH ranges, but that a number of compounds in this structure class are indefinitely stable under physiologically relevant pH conditions; one bicyclic example was additionally water-soluble. We examined the effect of structure on the reversibility of amide bond hydrolysis, which we attributed to the transannular nature of the amino acid analogs. These data suggest that medium-bridged lactams of these types should provide useful platforms for studying the behavior of twisted amides in aqueous systems. PMID:19178141
The SU(∞) twisted gradient flow running coupling
Energy Technology Data Exchange (ETDEWEB)
Pérez, Margarita García [Instituto de Física Teórica UAM-CSIC,Nicolás Cabrera 13-15, E-28049-Madrid (Spain); González-Arroyo, Antonio [Instituto de Física Teórica UAM-CSIC,Nicolás Cabrera 13-15, E-28049-Madrid (Spain); Departamento de Física Teórica, C-15, Universidad Autónoma de Madrid,E-28049-Madrid (Spain); Keegan, Liam [PH-TH, CERN,CH-1211 Geneva 23 (Switzerland); Okawa, Masanori [Graduate School of Science, Hiroshima University,Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
2015-01-09
We measure the running of the SU(∞) ’t Hooft coupling by performing a step scaling analysis of the Twisted Eguchi-Kawai (TEK) model, the SU(N) gauge theory on a single site lattice with twisted boundary conditions. The computation relies on the conjecture that finite volume effects for SU(N) gauge theories defined on a 4-dimensional twisted torus are controlled by an effective size parameter l-tilde=l√N, with l the torus period. We set the scale for the running coupling in terms of l-tilde and use the gradient flow to define a renormalized ’t Hooft coupling λ(l-tilde). In the TEK model, this idea allows the determination of the running of the coupling through a step scaling procedure that uses the rank of the group as a size parameter. The continuum renormalized coupling constant is extracted in the zero lattice spacing limit, which in the TEK model corresponds to the large N limit taken at fixed value of λ(l-tilde). The coupling constant is thus expected to coincide with that of the ordinary pure gauge theory at N=∞. The idea is shown to work and permits us to follow the evolution of the coupling over a wide range of scales. At weak coupling we find a remarkable agreement with the perturbative two-loop formula for the running coupling.
The $SU(\\infty)$ twisted gradient flow running coupling
Pérez, Margarita García; Keegan, Liam; Okawa, Masanori
2015-01-01
We measure the running of the $SU(\\infty)$ 't Hooft coupling by performing a step scaling analysis of the Twisted Eguchi-Kawai (TEK) model, the SU($N$) gauge theory on a single site lattice with twisted boundary conditions. The computation relies on the conjecture that finite volume effects for SU(N) gauge theories defined on a 4-dimensional twisted torus are controlled by an effective size parameter $\\tilde l = l \\sqrt{N}$, with $l$ the torus period. We set the scale for the running coupling in terms of $\\tilde l$ and use the gradient flow to define a renormalized 't Hooft coupling $\\lambda(\\tilde l)$. In the TEK model, this idea allows the determination of the running of the coupling through a step scaling procedure that uses the rank of the group as a size parameter. The continuum renormalized coupling constant is extracted in the zero lattice spacing limit, which in the TEK model corresponds to the large $N$ limit taken at fixed value of $\\lambda(\\tilde l)$. The coupling constant is thus expected to coinc...
Zhang, J; Talbot, W S; Schier, A F
1998-01-23
The zebrafish one-eyed pinhead (oep) mutation disrupts embryonic development, resulting in cyclopia and defects in endoderm, prechordal plate, and ventral neuroectoderm formation. We report the molecular isolation of oep using a positional cloning approach. The oep gene encodes a novel EGF-related protein with similarity to the EGF-CFC proteins cripto, cryptic, and FRL-1. Wild-type oep protein contains a functional signal sequence and is membrane-associated. Following ubiquitous maternal and zygotic expression, highest levels of oep mRNA are found in the gastrula margin and in axial structures and forebrain. Widespread misexpression of both membrane-attached and secreted forms of oep rescues prechordal plate and forebrain development in mutant embryos but does not lead to the ectopic induction of these cell types in wild-type fish. These results establish an essential but permissive role for an EGF-related ligand during vertebrate gastrulation.
Ferrer-Vaquer, Anna; Hadjantonakis, Anna-Katerina
2012-01-01
Congenital malformations represent approximately 3 in 100 live births within the human population. Understanding their pathogenesis and ultimately formulating effective treatments is underpinned by knowledge of the events and factors that regulate normal embryonic development. Studies in model organisms, primarily in the mouse, the most prominent genetically tractable mammalian model, have equipped us with a rudimentary understanding of mammalian development from early lineage commitment to morphogenetic processes. In this way information provided by studies in the mouse can, in some cases, be used to draw parallels with other mammals, including human. Here we provide an overview of our current understanding of the general sequence of developmental events from early cell cleavages to gastrulation and axis extension occurring in human embryos. We will also review some of the rare birth defects occurring at these stages, in particular those resulting in conjoined twinning or caudal dysgenesis. PMID:24014416
Schambra, Uta B; Nunley, Kevin; Harrison, Theresa A; Lewis, C Nicole
In a previous study we used a mouse model for ethanol exposure during gastrulation or neurulation to investigate the effects of modest and occasional human drinking during the 3rd or 4th week of pregnancy (Schambra et al., 2015). Pregnant C57Bl/6J mice were treated by gavage during gastrulation on gestational day (GD) 7 or neurulation on GD8 with 2 doses 4h apart of either 2.4 or 2.9g ethanol/kg body weight, resulting in peak blood ethanol concentrations (BECs) of 104 and 177mg/dl, respectively. We found that mice exposed to the low dose on either day were significantly delayed in their neonatal sensorimotor development. In the present study, we tested the same cohort of mice in an open field as juveniles on postnatal day (PD) 23-25 and as young adults on PD65-67 for prenatal ethanol effects on exploration and emotionality with measures of activity, rearing, grooming and defecation. We evaluated the effects of dose, sex, day of treatment and day of birth by multiple regression analyses. We found that, compared to the respective gavage controls, juvenile mice that had been prenatally exposed to the low BEC on either GD7 or GD8 were significantly hypoactive on the first 2 test days, reared significantly more on the last 2 test days, and groomed and defecated significantly more on all 3 test days. Only mice that had been treated on GD7 remained hypoactive as adults. Juvenile mice prenatally exposed to the moderate BEC on GD7 groomed significantly more, while those exposed on GD8 reared and defecated significantly more. Sex differences were highly significant in adult control mice, with control males less active and more emotional than females. Similar, but smaller, sex differences were also evident in adults exposed to ethanol prenatally. Persistence into later life of a deleterious effect of premature birth (i.e., birth on GD19 rather than GD20) on weight and behavior was not consistently supported by these data. Importantly, mice shown previously to be delayed in
Euclidean supersymmetry, twisting and topological sigma models
International Nuclear Information System (INIS)
Hull, C.M.; Lindstroem, U.; Santos, L. Melo dos; Zabzine, M.; Unge, R. von
2008-01-01
We discuss two dimensional N-extended supersymmetry in Euclidean signature and its R-symmetry. For N = 2, the R-symmetry is SO(2) x SO(1, 1), so that only an A-twist is possible. To formulate a B-twist, or to construct Euclidean N = 2 models with H-flux so that the target geometry is generalised Kahler, it is necessary to work with a complexification of the sigma models. These issues are related to the obstructions to the existence of non-trivial twisted chiral superfields in Euclidean superspace.
On the twist-2 and twist-3 contributions to the spin-dependent electroweak structure functions
International Nuclear Information System (INIS)
Bluemlein, J.; Kochelev, N.
1997-01-01
The twist-2 and twist-3 contributions of the polarized deep-inelastic structure functions are calculated both for neutral and charged current interactions using the operator product expansion in lowest order in QCD. The relations between the different structure functions are determined. New integral relations are derived between the twist-2 contributions of the structure functions g 3 (x,Q 2 ) and g 5 (x,Q 2 ) and between combinations of the twist-3 contributions to the structure functions g 2 (x,Q 2 ) and g 3 (x,Q 2 ). The sum rules for polarized deep-inelastic scattering are discussed in detail. (orig.)
Twisted Vector Bundles on Pointed Nodal Curves
Indian Academy of Sciences (India)
Abstract. Motivated by the quest for a good compactification of the moduli space of -bundles on a nodal curve we establish a striking relationship between Abramovich's and Vistoli's twisted bundles and Gieseker vector bundles.
Twisted covariant noncommutative self-dual gravity
International Nuclear Information System (INIS)
Estrada-Jimenez, S.; Garcia-Compean, H.; Obregon, O.; Ramirez, C.
2008-01-01
A twisted covariant formulation of noncommutative self-dual gravity is presented. The formulation for constructing twisted noncommutative Yang-Mills theories is used. It is shown that the noncommutative torsion is solved at any order of the θ expansion in terms of the tetrad and some extra fields of the theory. In the process the first order expansion in θ for the Plebanski action is explicitly obtained.
Nonlinear physics of twisted magnetic field lines
International Nuclear Information System (INIS)
Yoshida, Zensho
1998-01-01
Twisted magnetic field lines appear commonly in many different plasma systems, such as magnetic ropes created through interactions between the magnetosphere and the solar wind, magnetic clouds in the solar wind, solar corona, galactic jets, accretion discs, as well as fusion plasma devices. In this paper, we study the topological characterization of twisted magnetic fields, nonlinear effect induced by the Lorentz back reaction, length-scale bounds, and statistical distributions. (author)
OAM mode converter in twisted fibers
DEFF Research Database (Denmark)
Usuga Castaneda, Mario A.; Beltran-Mejia, Felipe; Cordeiro, Cristiano
2014-01-01
We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA.......We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA....
Further Generalisations of Twisted Gabidulin Codes
DEFF Research Database (Denmark)
Puchinger, Sven; Rosenkilde, Johan Sebastian Heesemann; Sheekey, John
2017-01-01
We present a new family of maximum rank distance (MRD) codes. The new class contains codes that are neither equivalent to a generalised Gabidulin nor to a twisted Gabidulin code, the only two known general constructions of linear MRD codes.......We present a new family of maximum rank distance (MRD) codes. The new class contains codes that are neither equivalent to a generalised Gabidulin nor to a twisted Gabidulin code, the only two known general constructions of linear MRD codes....
Twist operator correlation functions in O(n) loop models
International Nuclear Information System (INIS)
Simmons, Jacob J H; Cardy, John
2009-01-01
Using conformal field theoretic methods we calculate correlation functions of geometric observables in the loop representation of the O(n) model at the critical point. We focus on correlation functions containing twist operators, combining these with anchored loops, boundaries with SLE processes and with double SLE processes. We focus further upon n = 0, representing self-avoiding loops, which corresponds to a logarithmic conformal field theory (LCFT) with c = 0. In this limit the twist operator plays the role of a 0-weight indicator operator, which we verify by comparison with known examples. Using the additional conditions imposed by the twist operator null states, we derive a new explicit result for the probabilities that an SLE 8/3 winds in various ways about two points in the upper half-plane, e.g. that the SLE passes to the left of both points. The collection of c = 0 logarithmic CFT operators that we use deriving the winding probabilities is novel, highlighting a potential incompatibility caused by the presence of two distinct logarithmic partners to the stress tensor within the theory. We argue that both partners do appear in the theory, one in the bulk and one on the boundary and that the incompatibility is resolved by restrictive bulk-boundary fusion rules
International Nuclear Information System (INIS)
Jaisankar, S.; Radhakrishnan, T.K.; Sheeba, K.N.
2011-01-01
Research highlights: → Conventional solar heaters are inefficient due to poor convective heat transfer. → Twisted tapes improve the heat transfer rate in solar water heater system. → Increase in outlet water temperature by 15 o C through the use of twisted tapes. →Thermal performance of twisted tape collector is 19% more than plain tube system. → Reduces collector area (0.6 m 2 ) whereas area for conventional collector is 1 m 2 . -- Abstract: Experimental investigation of heat transfer, friction factor and thermal performance of thermosyphon solar water heater system fitted with helical and Left-Right twist of twist ratio 3 has been performed and presented. The helical twisted tape induces swirl flow inside the riser tubes unidirectional over the length. But, in Left-Right system the swirl flow is bidirectional which increases the heat transfer and pressure drop when compared to the helical system. The experimental heat transfer and friction factors characteristics are validated with theoretical equations and the deviation falls with in the acceptable limits. The results show that heat transfer enhancement in twisted tape collector is higher than the plain tube collector. Compared to helical and Left-Right twisted tape system of same twist ratio 3, maximum thermal performance is obtained for Left-Right twisted tape collector with increase in solar intensity.
RESONANT ABSORPTION OF AXISYMMETRIC MODES IN TWISTED MAGNETIC FLUX TUBES
Energy Technology Data Exchange (ETDEWEB)
Giagkiozis, I.; Verth, G. [Solar Plasma Physics Research Centre, School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield, S3 7RH (United Kingdom); Goossens, M.; Doorsselaere, T. Van [Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium); Fedun, V. [Department of Automatic Control and Systems Engineering, University of Sheffield, Mappin Street, Amy Johnson Building, Sheffield, S1 3JD (United Kingdom)
2016-06-01
It has been shown recently that magnetic twist and axisymmetric MHD modes are ubiquitous in the solar atmosphere, and therefore the study of resonant absorption for these modes has become a pressing issue because it can have important consequences for heating magnetic flux tubes in the solar atmosphere and the observed damping. In this investigation, for the first time, we calculate the damping rate for axisymmetric MHD waves in weakly twisted magnetic flux tubes. Our aim is to investigate the impact of resonant damping of these modes for solar atmospheric conditions. This analytical study is based on an idealized configuration of a straight magnetic flux tube with a weak magnetic twist inside as well as outside the tube. By implementing the conservation laws derived by Sakurai et al. and the analytic solutions for weakly twisted flux tubes obtained recently by Giagkiozis et al. we derive a dispersion relation for resonantly damped axisymmetric modes in the spectrum of the Alfvén continuum. We also obtain an insightful analytical expression for the damping rate in the long wavelength limit. Furthermore, it is shown that both the longitudinal magnetic field and the density, which are allowed to vary continuously in the inhomogeneous layer, have a significant impact on the damping time. Given the conditions in the solar atmosphere, resonantly damped axisymmetric modes are highly likely to be ubiquitous and play an important role in energy dissipation. We also suggest that, given the character of these waves, it is likely that they have already been observed in the guise of Alfvén waves.
On the twists of interplanetary magnetic flux ropes observed at 1 AU
Wang, Yuming; Zhuang, Bin; Hu, Qiang; Liu, Rui; Shen, Chenglong; Chi, Yutian
2016-10-01
Magnetic flux ropes (MFRs) are one kind of fundamental structures in the solar/space physics and involved in various eruption phenomena. Twist, characterizing how the magnetic field lines wind around a main axis, is an intrinsic property of MFRs, closely related to the magnetic free energy and stableness. Although the effect of the twist on the behavior of MFRs had been widely studied in observations, theory, modeling, and numerical simulations, it is still unclear how much amount of twist is carried by MFRs in the solar atmosphere and in heliosphere and what role the twist played in the eruptions of MFRs. Contrasting to the solar MFRs, there are lots of in situ measurements of magnetic clouds (MCs), the large-scale MFRs in interplanetary space, providing some important information of the twist of MFRs. Thus, starting from MCs, we investigate the twist of interplanetary MFRs with the aid of a velocity-modified uniform-twist force-free flux rope model. It is found that most of MCs can be roughly fitted by the model and nearly half of them can be fitted fairly well though the derived twist is probably overestimated by a factor of 2.5. By applying the model to 115 MCs observed at 1 AU, we find that (1) the twist angles of interplanetary MFRs generally follow a trend of about 0.6l/R radians, where l/R is the aspect ratio of a MFR, with a cutoff at about 12π radians AU-1, (2) most of them are significantly larger than 2.5π radians but well bounded by 2l/R radians, (3) strongly twisted magnetic field lines probably limit the expansion and size of MFRs, and (4) the magnetic field lines in the legs wind more tightly than those in the leading part of MFRs. These results not only advance our understanding of the properties and behavior of interplanetary MFRs but also shed light on the formation and eruption of MFRs in the solar atmosphere. A discussion about the twist and stableness of solar MFRs are therefore given.
Soft tissue twisting injuries of the knee
International Nuclear Information System (INIS)
Magee, T.; Shapiro, M.
2001-01-01
Twisting injuries occur as a result of differential motion of different tissue types in injuries with some rotational force. These injuries are well described in brain injuries but, to our knowledge, have not been described in the musculoskeletal literature. We correlated the clinical examination and MR findings of 20 patients with twisting injuries of the soft tissues around the knee. Design and patients: We prospectively followed the clinical courses of 20 patients with knee injuries who had clinical histories and MR findings to suggest twisting injuries of the subcutaneous tissues. Patients with associated internal derangement of the knee (i.e., meniscal tears, ligamentous or bone injuries) were excluded from this study. MR findings to suggest twisting injuries included linear areas of abnormal dark signal on T1-weighted sequences and abnormal bright signal on T2-weighted or short tau inversion recovery (STIR) sequences and/or signal to suggest hemorrhage within the subcutaneous tissues. These MR criteria were adapted from those established for indirect musculotendinous junction injuries. Results: All 20 patients presented with considerable pain that suggested internal derangement on physical examination by the referring orthopedic surgeons. All presented with injuries associated with rotational force. The patients were placed on a course of protected weight-bearing of the affected extremity for 4 weeks. All patients had pain relief by clinical examination after this period of protected weight-bearing. Twisting injuries of the soft tissues can result in considerable pain that can be confused with internal derangement of the knee on physical examination. Soft tissue twisting injuries need to be recognized on MR examinations as they may be the cause of the patient's pain despite no MR evidence of internal derangement of the knee. The demonstration of soft tissue twisting injuries in a patient with severe knee pain but no documented internal derangement on MR
Topological twist in four dimensions, R-duality and hyperinstantons
International Nuclear Information System (INIS)
Anselmi, D.; Fre, P.
1993-01-01
In this paper we continue the programme of topologically twisting N=2 theories in D=4, focusing on the coupling of vector multiplets to N=2 supergravity. We show that in the minimal case, namely when the special gometry prepotential F(X) is a quadratic polynomial, the theory has a so far unknown on-shell U(1) symmetry, that we name R-duality. R-duality is a generalization of the chiral-dual on-shell symmetry of N=2 pure supergravity and of the R-symmetry of N=2 super Yang-Mills theory. Thanks to this, the theory can be topologically twisted and topologically shifted, precisely as pure N=2 supergravity, to yield a natural coupling of topological gravity to topological Yang-Mills theory. The gauge-fixing condition that emerges from the twisting is the self-duality condition on the gauge field strength and on the spin connection. Hence our theory reduces to intersection theory in the moduli-space of gauge instantons living in gravitational instanton backgrounds. We remark that, for deep properties of the parent N=2 theory, the topological Yang-Mills theory we obtain by taking the flat space limit of our gravity-coupled lagrangian is different from the Donaldson theory constructed by Witten. Whether this difference is substantial and what its geometrical implications may be is yet to be seen. We also discuss the topological twist of the hypermultiplets leading to topological quaternionic sigma-models. The instantons of these models, named by us hyperinstantons, correspond to a notion of triholomorphic mappings discussed in the paper. In all cases the new ghost number is the sum of the old ghost number plus the R-duality charge. The observables described by the theory are briefly discussed. In conclusion, the topological twist of the complete N=2 theory defines intersection theory in the moduli-space of gauge instantons plus gravitational instantons plus hyperinstantons. This is possibly a new subject for further mathematical investigation. (orig.)
On the restoration of supersymmetry in twisted two-dimensional lattice Yang-Mills theory
International Nuclear Information System (INIS)
Catterall, Simon
2007-01-01
We study a discretization of N = 2 super Yang-Mills theory which possesses a single exact supersymmetry at non-zero lattice spacing. This supersymmetry arises after a reformulation of the theory in terms of twisted fields. In this paper we derive the action of the other twisted supersymmetries on the component fields and study, using Monte Carlo simulation, a series of corresponding Ward identities. Our results for SU(2) and SU(3) support a restoration of these additional supersymmetries without fine tuning in the infinite volume continuum limit. Additionally we present evidence supporting a restoration of (twisted) rotational invariance in the same limit. Finally we have examined the distribution of scalar field eigenvalues and find evidence for power law tails extending out to large eigenvalue. We argue that these tails indicate that the classical moduli space does not survive in the quantum theory
Nucleon electromagnetic form factors in twisted mass lattice QCD
International Nuclear Information System (INIS)
Alexandrou, C.; Jansen, K.; Korzec, T.; Humboldt Univ. Berlin
2011-02-01
We present results on the nucleon electromagnetic form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length L=2.1 fm and L=2.8 fm. Cut-off effects are investigated using three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm. The nucleon magnetic moment, Dirac and Pauli radii are obtained in the continuum limit and chirally extrapolated to the physical pion mass allowing for a comparison with experiment. (orig.)
Nucleon electromagnetic form factors in twisted mass lattice QCD
International Nuclear Information System (INIS)
Alexandrou, C.; Brinet, M.; Carbonell, J.; Harraud, P. A.; Papinutto, M.; Guichon, P.; Jansen, K.; Korzec, T.; Constantinou, M.
2011-01-01
We present results on the nucleon electromagnetic form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length L=2.1 fm and L=2.8 fm. Cutoff effects are investigated using three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm. The nucleon magnetic moment, Dirac and Pauli radii are obtained in the continuum limit and chirally extrapolated to the physical pion mass allowing for a comparison with experiment.
Bogoliubov coefficients for the twist operator in the D1D5 CFT
Directory of Open Access Journals (Sweden)
Zaq Carson
2014-12-01
Full Text Available The D1D5 CFT is a holographic dual of a near-extremal black hole in string theory. The interaction in this theory involves a twist operator which joins together different copies of a free CFT. Given a large number of D1 and D5 branes, the effective length of the circle on which the CFT lives is very large. We develop a technique to study the effect of the twist operator in the limit where the wavelengths of excitations are short compared to this effective length, which we call the ‘continuum limit’. The method uses Bogoliubov coefficients to compute the effect of the twist operator in this limit. For bosonic fields, we use the method to reproduce recent results describing the effect of the twist operator when it links together CFT copies with windings M and N, producing a copy of winding M+N. We also comment on possible generalizations of our results. The methods developed here may help in understanding the twist interaction at higher orders. This in turn should provide insight into the thermalization process in the D1D5 CFT, which gives a holographic description of black hole formation.
Electrically Controllable Magnetism in Twisted Bilayer Graphene.
Gonzalez-Arraga, Luis A; Lado, J L; Guinea, Francisco; San-Jose, Pablo
2017-09-08
Twisted graphene bilayers develop highly localized states around AA-stacked regions for small twist angles. We show that interaction effects may induce either an antiferromagnetic or a ferromagnetic (FM) polarization of said regions, depending on the electrical bias between layers. Remarkably, FM-polarized AA regions under bias develop spiral magnetic ordering, with a relative 120° misalignment between neighboring regions due to a frustrated antiferromagnetic exchange. This remarkable spiral magnetism emerges naturally without the need of spin-orbit coupling, and competes with the more conventional lattice-antiferromagnetic instability, which interestingly develops at smaller bias under weaker interactions than in monolayer graphene, due to Fermi velocity suppression. This rich and electrically controllable magnetism could turn twisted bilayer graphene into an ideal system to study frustrated magnetism in two dimensions.
Higher-twist correlations in polarized hadrons
International Nuclear Information System (INIS)
Tangerman, R.D.
1996-01-01
In this thesis we studied the response of polarized hadrons to several high-energy probes, working in the framework of the field theoretic model. Emphasis is laid upon higher-twist effects such as quark transverse momentum. The inclusive DIS process is very well suited to study QCD. From general principles we were able to derive four positivity constraints on the structure functions without invoking the helicity formalism. The on-shell quark model is used to illustrate these constraints. Subseqeuently, we concentrated on the higher-twist structure function g 2 (x,Q 2 ). (orig./HSI)
Factorising the 3D topologically twisted index
Cabo-Bizet, Alejandro
2017-04-01
We explore the path integration — upon the contour of hermitian (non-auxliary) field configurations — of topologically twisted N=2 Chern-Simons-matter theory (TTCSM) on {S}_2 times a segment. In this way, we obtain the formula for the 3D topologically twisted index, first as a convolution of TTCSM on {S}_2 times halves of {S}_1 , second as TTCSM on {S}_2 times {S}_1 — with a puncture, — and third as TTCSM on {S}_2× {S}_1 . In contradistinction to the first two cases, in the third case, the vector multiplet auxiliary field D is constrained to be anti-hermitian.
Energy Technology Data Exchange (ETDEWEB)
Ebrahimi, Zanyar; Karami, Kayoomars [Department of Physics, University of Kurdistan, Pasdaran Street, P.O. Box 66177-15175, Sanandaj (Iran, Islamic Republic of); Soler, Roberto, E-mail: z.ebrahimi@uok.ac.ir [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)
2017-08-10
There is observational evidence for the existence of a twisted magnetic field in the solar corona. This inspires us to investigate the effect of a twisted magnetic field on the evolution of magnetohydrodynamic (MHD) kink waves in coronal loops. With this aim, we solve the incompressible linearized MHD equations in a magnetically twisted nonuniform coronal flux tube in the limit of long wavelengths. Our results show that a twisted magnetic field can enhance or diminish the rate of phase mixing of the Alfvén continuum modes and the decay rate of the global kink oscillation depending on the twist model and the sign of the longitudinal ( k{sub z} ) and azimuthal ( m ) wavenumbers. Also, our results confirm that in the presence of a twisted magnetic field, when the sign of one of the two wavenumbers m and k {sub z} is changed, the symmetry with respect to the propagation direction is broken. Even a small amount of twist can have an important impact on the process of energy cascading to small scales.
A higher twist correction to heavy quark production
International Nuclear Information System (INIS)
Brodsky, S.J.; Gunion, J.F.; Soper, D.E.
1987-06-01
The leading twist prediction for heavy quark production and a model for a higher twist correction that may be important for charm production was discussed. The correction arises from the interaction of the charm quark with spectator quarks
Twist operators in N=4 beta-deformed theory
de Leeuw, M.; Łukowski, T.
2010-01-01
In this paper we derive both the leading order finite size corrections for twist-2 and twist-3 operators and the next-to-leading order finite-size correction for twist-2 operators in beta-deformed SYM theory. The obtained results respect the principle of maximum transcendentality as well as
Energy Technology Data Exchange (ETDEWEB)
Song, Min Seop; Park, So Hyun; Kim, Eung Soo [Seoul National Univ., Seoul (Korea, Republic of)
2014-10-15
Many researchers conducted experiments and numerical simulations to measure or predict a Nusselt number or a friction factor in a pipe with a twisted tape while some other studies focused on the heat transfer performance enhancement using various twisted tape configurations. However, since the optical access to the inner space of a pipe with a twisted tape was limited, the detailed flow field data were not obtainable so far. Thus, researchers mainly relied on the numerical simulations to obtain the data of the flow field. In this study, a 3D printing technique was used to manufacture a transparent test section for optical access. And also, a noble refractive index matching technique was used to eliminate optical distortion. This two combined techniques enabled to measure the velocity profile with Particle Image Velocimetry (PIV). The measured velocity field data can be used either to understand the fundamental flow characteristics around a twisted tape or to validate turbulence models in Computational Fluid Dynamics (CFD). In this study, the flow field in the test-section was measured for various flow conditions and it was finally compared with numerically calculated data. Velocity fields in a pipe with a classic twisted tape was measured using a particle image velocimetry (PIV) system. To obtain undistorted particle images, a noble optical technique, refractive index matching, was used and it was proved that high-quality image can be obtained from this experimental equipment. The velocity data from the PIV was compared with the CFD simulations.
International Nuclear Information System (INIS)
Song, Min Seop; Park, So Hyun; Kim, Eung Soo
2014-01-01
Many researchers conducted experiments and numerical simulations to measure or predict a Nusselt number or a friction factor in a pipe with a twisted tape while some other studies focused on the heat transfer performance enhancement using various twisted tape configurations. However, since the optical access to the inner space of a pipe with a twisted tape was limited, the detailed flow field data were not obtainable so far. Thus, researchers mainly relied on the numerical simulations to obtain the data of the flow field. In this study, a 3D printing technique was used to manufacture a transparent test section for optical access. And also, a noble refractive index matching technique was used to eliminate optical distortion. This two combined techniques enabled to measure the velocity profile with Particle Image Velocimetry (PIV). The measured velocity field data can be used either to understand the fundamental flow characteristics around a twisted tape or to validate turbulence models in Computational Fluid Dynamics (CFD). In this study, the flow field in the test-section was measured for various flow conditions and it was finally compared with numerically calculated data. Velocity fields in a pipe with a classic twisted tape was measured using a particle image velocimetry (PIV) system. To obtain undistorted particle images, a noble optical technique, refractive index matching, was used and it was proved that high-quality image can be obtained from this experimental equipment. The velocity data from the PIV was compared with the CFD simulations
Twisted Frobenius Identities from Vertex Operator Superalgebras
Directory of Open Access Journals (Sweden)
Alexander Zuevsky
2017-01-01
Full Text Available In consideration of the continuous orbifold partition function and a generating function for all n-point correlation functions for the rank two free fermion vertex operator superalgebra on the self-sewing torus, we introduce the twisted version of Frobenius identity.
Magnetization Modeling of Twisted Superconducting Filaments
Satiramatekul, T; Devred, Arnaud; Leroy, Daniel
2007-01-01
This paper presents a new Finite Element numerical method to analyze the coupling between twisted filaments in a superconducting multifilament composite wire. To avoid the large number of elements required by a 3D code, the proposed method makes use of the energy balance principle in a 2D code. The relationship between superconductor critical current density and local magnetic flux density is implemented in the program for the Bean and modified Kim models. The modeled wire is made up of six filaments twisted together and embedded in a lowresistivity matrix. Computations of magnetization cycle and of the electric field pattern have been performed for various twist pitch values in the case of a pure copper matrix. The results confirm that the maximum magnetization depends on the matrix conductivity, the superconductor critical current density, the applied field frequency, and the filament twist pitch. The simulations also lead to a practical criterion for wire design that can be used to assess whether or not th...
Hilbert's Grand Hotel with a series twist
Wijeratne, Chanakya; Mamolo, Ami; Zazkis, Rina
2014-08-01
This paper presents a new twist on a familiar paradox, linking seemingly disparate ideas under one roof. Hilbert's Grand Hotel, a paradox which addresses infinite set comparisons is adapted and extended to incorporate ideas from calculus - namely infinite series. We present and resolve several variations, and invite the reader to explore his or her own variations.
On the Compton Twist-3 Asymmetries
International Nuclear Information System (INIS)
Korotkiyan, V.M.; Teryaev, O.V.
1994-01-01
The 'fermionic poles' contribution to the twist-3 single asymmetry in the gluon Compton process is calculated. The 'gluonic poles' existence seems to contradict the density matrix positivity. Qualitative predictions for the direct photon and jets asymmetries are presented. 13 refs., 2 figs
Generalized Weyl modules for twisted current algebras
Makedonskyi, I. A.; Feigin, E. B.
2017-08-01
We introduce the notion of generalized Weyl modules for twisted current algebras. We study their representation-theoretic and combinatorial properties and also their connection with nonsymmetric Macdonald polynomials. As an application, we compute the dimension of the classical Weyl modules in the remaining unknown case.
Hardy Inequalities in Globally Twisted Waveguides
Czech Academy of Sciences Publication Activity Database
Briet, Ph.; Hammedi, H.; Krejčiřík, David
2015-01-01
Roč. 105, č. 7 (2015), s. 939-958 ISSN 0377-9017 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : quantum waveguides * twisted tubes * Dirichlet Laplacian * Hardy inequality Subject RIV: BE - Theoretical Physics Impact factor: 1.517, year: 2015
Morphing wing structure with controllable twist based on adaptive bending-twist coupling
Raither, Wolfram; Heymanns, Matthias; Bergamini, Andrea; Ermanni, Paolo
2013-06-01
A novel semi-passive morphing airfoil concept based on variable bending-twist coupling induced by adaptive shear center location and torsional stiffness is presented. Numerical parametric studies and upscaling show that the concept relying on smart materials permits effective twist control while offering the potential of being lightweight and energy efficient. By means of an experimental characterization of an adaptive beam and a scaled adaptive wing structure, effectiveness and producibility of the structural concept are demonstrated.
Morphing wing structure with controllable twist based on adaptive bending–twist coupling
International Nuclear Information System (INIS)
Raither, Wolfram; Heymanns, Matthias; Ermanni, Paolo; Bergamini, Andrea
2013-01-01
A novel semi-passive morphing airfoil concept based on variable bending–twist coupling induced by adaptive shear center location and torsional stiffness is presented. Numerical parametric studies and upscaling show that the concept relying on smart materials permits effective twist control while offering the potential of being lightweight and energy efficient. By means of an experimental characterization of an adaptive beam and a scaled adaptive wing structure, effectiveness and producibility of the structural concept are demonstrated. (paper)
Twisted boundary conditions: a non-perturbative probe for pure non-abelian gauge theories
International Nuclear Information System (INIS)
Baal, P. van.
1984-01-01
In this thesis the author describes a pure non-abelian gauge theory on the hypertorus with gauge group SU(N). To test the flux tube picture he has studied the large distance limit of this theory, leading to a large coupling constant. To tackle this problem, he describes two approaches, in both of which twisted boundary conditions play an important role. (Auth.)
A novel role for Twist-1 in pulp homeostasis.
Galler, K M; Yasue, A; Cavender, A C; Bialek, P; Karsenty, G; D'Souza, R N
2007-10-01
The molecular mechanisms that maintain the equilibrium of odontoblast progenitor cells in dental pulp are unknown. Here we tested whether homeostasis in dental pulp is modulated by Twist-1, a nuclear protein that partners with Runx2 during osteoblast differentiation. Our analysis of Twist-1(+/-) mice revealed phenotypic changes that involved an earlier onset of dentin matrix formation, increased alkaline phosphatase activity, and pulp stones within the pulp. RT-PCR analyses revealed Twist-1 expression in several adult organs, including pulp. Decreased levels of Twist-1 led to higher levels of type I collagen and Dspp gene expression in perivascular cells associated with the pulp stones. In mice heterozygous for both Twist-1 and Runx2 inactivation, the phenotype of pulp stones appeared completely rescued. These findings suggest that Twist-1 plays a key role in restraining odontoblast differentiation, thus maintaining homeostasis in dental pulp. Furthermore, Twist-1 functions in dental pulp are dependent on its interaction with Runx2.
M(atrix) theory on an orbifold and twisted membrane
International Nuclear Information System (INIS)
Kim, N.
1997-01-01
M(atrix) theory on an orbifold and classical two-branes therein are studied with particular emphasis on heterotic M(atrix) theory on S 1 / Z 2 relevant to strongly coupled heterotic and dual type IA string theories. By analyzing the orbifold condition on Chan-Paton factors, we show that three choices of gauge group are possible for heterotic M(atrix) theory: SO(2N), SO(2N+1) or USp(2N). By examining the area-preserving diffeomorphism that underlies the M(atrix) theory, we find that each choice of gauge group restricts the possible topologies of two-branes. The result suggests that only the choice of SO(2N) or SO(2N+1) allows open two-branes, and hence, is relevant to heterotic M(atrix) theory. We show that the requirement of both local vacuum energy cancellation and of world-sheet anomaly cancellation of the resulting heterotic string identifies supersymmetric twisted sector spectra with sixteen fundamental representation spinors from each of the two fixed points. Twisted open and closed two-brane configurations are obtained in the large N limit. (orig.)
Friction spinning - Twist phenomena and the capability of influencing them
Lossen, Benjamin; Homberg, Werner
2016-10-01
The friction spinning process can be allocated to the incremental forming techniques. The process consists of process elements from both metal spinning and friction welding. The selective combination of process elements from these two processes results in the integration of friction sub-processes in a spinning process. This implies self-induced heat generation with the possibility of manufacturing functionally graded parts from tube and sheets. Compared with conventional spinning processes, this in-process heat treatment permits the extension of existing forming limits and also the production of more complex geometries. Furthermore, the defined adjustment of part properties like strength, grain size/orientation and surface conditions can be achieved through the appropriate process parameter settings and consequently by setting a specific temperature profile in combination with the degree of deformation. The results presented from tube forming start with an investigation into the resulting twist phenomena in flange processing. In this way, the influence of the main parameters, such as rotation speed, feed rate, forming paths and tool friction surface, and their effects on temperature, forces and finally the twist behavior are analyzed. Following this, the significant correlations with the parameters and a new process strategy are set out in order to visualize the possibility of achieving a defined grain texture orientation.
Nucleon and delta masses in twisted mass chiral perturbation theory
International Nuclear Information System (INIS)
Walker-Loud, Andre; Wu, Jackson M.S.
2005-01-01
We calculate the masses of the nucleons and deltas in twisted mass heavy baryon chiral perturbation theory. We work to quadratic order in a power counting scheme in which we treat the lattice spacing, a, and the quark masses, m q , to be of the same order. We give expressions for the mass and the mass splitting of the nucleons and deltas both in and away from the isospin limit. We give an argument using the chiral Lagrangian treatment that, in the strong isospin limit, the nucleons remain degenerate and the delta multiplet breaks into two degenerate pairs to all orders in chiral perturbation theory. We show that the mass splitting between the degenerate pairs of the deltas first appears at quadratic order in the lattice spacing. We discuss the subtleties in the effective chiral theory that arise from the inclusion of isospin breaking
A New Twisting Somersault: 513XD
Tong, William; Dullin, Holger R.
2017-12-01
We present the mathematical framework of an athlete modelled as a system of coupled rigid bodies to simulate platform and springboard diving. Euler's equations of motion are generalised to non-rigid bodies and are then used to innovate a new dive sequence that in principle can be performed by real-world athletes. We begin by assuming that shape changes are instantaneous so that the equations of motion simplify enough to be solved analytically, and then use this insight to present a new dive (513XD) consisting of 1.5 somersaults and five twists using realistic shape changes. Finally, we demonstrate the phenomenon of converting pure somersaulting motion into pure twisting motion by using a sequence of impulsive shape changes, which may have applications in other fields such as space aeronautics.
Chiral tunneling in a twisted graphene bilayer.
He, Wen-Yu; Chu, Zhao-Dong; He, Lin
2013-08-09
The perfect transmission in a graphene monolayer and the perfect reflection in a Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in a twisted graphene bilayer show an adjustable probability of chiral tunneling for normal incidence: they can be changed from perfect tunneling to partial or perfect reflection, or vice versa, by controlling either the height of the barrier or the incident energy. As well as addressing basic physics about how the chiral fermions with different chiralities tunnel through a barrier, our results provide a facile route to tune the electronic properties of the twisted graphene bilayer.
Factorising the 3D topologically twisted index
Energy Technology Data Exchange (ETDEWEB)
Cabo-Bizet, Alejandro [Instituto de Astronomía y Física del Espacio (CONICET-UBA),Ciudad Universitaria, C.P. 1428, Buenos Aires (Argentina)
2017-04-20
We explore the path integration — upon the contour of hermitian (non-auxliary) field configurations — of topologically twisted N=2 Chern-Simons-matter theory (TTCSM) on S{sub 2} times a segment. In this way, we obtain the formula for the 3D topologically twisted index, first as a convolution of TTCSM on S{sub 2} times halves of S{sub 1}, second as TTCSM on S{sub 2} times S{sub 1} — with a puncture, — and third as TTCSM on S{sub 2}×S{sub 1}. In contradistinction to the first two cases, in the third case, the vector multiplet auxiliary field D is constrained to be anti-hermitian.
IRONY IN CHARLES DICKEN'S OLIVER TWIST
Directory of Open Access Journals (Sweden)
Ika Kana Trisnawati
2016-05-01
Full Text Available This paper describes the types of irony used by Charles Dickens in his notable early work, Oliver Twist, as well as the reasons the irony was chosen. As a figurative language, irony is utilized to express one’s complex feelings without truly saying them. In Oliver Twist, Dickens brought the readers some real social issues wrapped in dark, deep written expressions of irony uttered by the characters of his novel. Undoubtedly, the novel had left an impact to the British society at the time. The irony Dickens displayed here includes verbal, situational, and dramatic irony. His choice of irony made sense as he intended to criticize the English Poor Laws and to touch the public sentiment. He wanted to let the readers go beyond what was literally written and once they discovered what the truth was, they would eventually understand Dickens’ purposes.
Leibniz algebroids, twistings and exceptional generalized geometry
Baraglia, D.
2012-05-01
We investigate a class of Leibniz algebroids which are invariant under diffeomorphisms and symmetries involving collections of closed forms. Under appropriate assumptions we arrive at a classification which in particular gives a construction starting from graded Lie algebras. In this case the Leibniz bracket is a derived bracket and there are higher derived brackets resulting in an L∞-structure. The algebroids can be twisted by a non-abelian cohomology class and we prove that the twisting class is described by a Maurer-Cartan equation. For compact manifolds we construct a Kuranishi moduli space of this equation which is shown to be affine algebraic. We explain how these results are related to exceptional generalized geometry.
Valve-aided twisted Savonius rotor
Energy Technology Data Exchange (ETDEWEB)
Jaya Rajkumar, M.; Saha, U.K.
2006-05-15
Accessories, such as end plates, deflecting plates, shielding and guide vanes, may increase the power of a Savonius rotor, but make the system structurally complex. In such cases, the rotor can develop a relatively large torque at small rotational speeds and is cheap to build, however it harnesses only a small fraction of the incident wind energy. Another proposition for increasing specific output is to place non-return valves inside the concave side of the blades. Such methods have been studied experimentally with a twisted-blade Thus improving a Savonius rotor's energy capture. This new concept has been named as the 'Valve-Aided Twisted Savonius'rotor. Tests were conducted in a low-speed wind tunnel to evaluate performance. This mechanism is found to be independent of flow direction, and shows potential for large machines. [Author].
Chiral Tunnelling in Twisted Graphene Bilayer
He, Wen-Yu; Chu, Zhao-Dong; He, Lin
2013-01-01
The perfect transmission in graphene monolayer and the perfect reflection in Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in twisted graphene bilayer shows adjustable probability of chiral tunnelling for normal incidence: they can be changed fr...
Vacuum expectation value of twist fields
Belitsky, A. V.
2017-09-01
Twist fields emerge in a number of physical applications ranging from entanglement entropy to scattering amplitudes in four-dimensional gauge theories. In this work, their vacuum expectation values are studied in the path integral framework. By performing a gauge transformation, their correlation functions are reduced to field theory of matter fields in external Aharonov-Bohm vortices. The resulting functional determinants are then analyzed within the zeta-function regularization for the spectrum of Bessel zeros, and concise formulas are derived.
Leibniz algebroids, twistings and exceptional generalized geometry
Baraglia, David
2011-01-01
We investigate a class of Leibniz algebroids which are invariant under diffeomorphisms and symmetries involving collections of closed forms. Under appropriate assumptions we arrive at a classification which in particular gives a construction starting from graded Lie algebras. In this case the Leibniz bracket is a derived bracket and there are higher derived brackets resulting in an $L_\\infty$-structure. The algebroids can be twisted by a non-abelian cohomology class and we prove that the twis...
Exploring exotic states with twisted boundary conditions
International Nuclear Information System (INIS)
Agadjanov, Dimitri
2017-01-01
he goal of this thesis is to develop methods to study the nature and properties of exotic hadrons from lattice simulations. The main focus lies in the application of twisted boundary conditions. The thesis consists of a general introduction and the collection of three papers, represented respectively in three chapters. The introduction of the thesis reviews the theoretical background, which is further used in the rest of the thesis. Further implementing partially twisted boundary conditions in the scalar sector of lattice QCD is studied. Then we develop a method to study the content of the exotic hadrons by determining the wave function renormalization constant from lattice simulations, exploiting the dependence of the spectrum on the twisted boundary conditions. The final chapter deals with a novel method to study the multi-channel scattering problem in a finite volume, which is relevant for exotic states. Its key idea is to extract the complex hadron-hadron optical potential, avoiding the difficulties, associated with the solution of the multi-channel Luescher equation.
Exploring exotic states with twisted boundary conditions
Energy Technology Data Exchange (ETDEWEB)
Agadjanov, Dimitri
2017-09-11
he goal of this thesis is to develop methods to study the nature and properties of exotic hadrons from lattice simulations. The main focus lies in the application of twisted boundary conditions. The thesis consists of a general introduction and the collection of three papers, represented respectively in three chapters. The introduction of the thesis reviews the theoretical background, which is further used in the rest of the thesis. Further implementing partially twisted boundary conditions in the scalar sector of lattice QCD is studied. Then we develop a method to study the content of the exotic hadrons by determining the wave function renormalization constant from lattice simulations, exploiting the dependence of the spectrum on the twisted boundary conditions. The final chapter deals with a novel method to study the multi-channel scattering problem in a finite volume, which is relevant for exotic states. Its key idea is to extract the complex hadron-hadron optical potential, avoiding the difficulties, associated with the solution of the multi-channel Luescher equation.
Transverse kink oscillations in the presence of twist
Terradas, J.; Goossens, M.
2012-12-01
Context. Magnetic twist is thought to play an important role in coronal loops. The effects of magnetic twist on stable magnetohydrodynamic (MHD) waves is poorly understood because they are seldom studied for relevant cases. Aims: The goal of this work is to study the fingerprints of magnetic twist on stable transverse kink oscillations. Methods: We numerically calculated the eigenmodes of propagating and standing MHD waves for a model of a loop with magnetic twist. The azimuthal component of the magnetic field was assumed to be small in comparison to the longitudinal component. We did not consider resonantly damped modes or kink instabilities in our analysis. Results: For a nonconstant twist the frequencies of the MHD wave modes are split, which has important consequences for standing waves. This is different from the degenerated situation for equilibrium models with constant twist, which are characterised by an azimuthal component of the magnetic field that linearly increases with the radial coordinate. Conclusions: In the presence of twist standing kink solutions are characterised by a change in polarisation of the transverse displacement along the tube. For weak twist, and in the thin tube approximation, the frequency of standing modes is unaltered and the tube oscillates at the kink speed of the corresponding straight tube. The change in polarisation is linearly proportional to the degree of twist. This has implications with regard to observations of kink modes, since the detection of this variation in polarisation can be used as an indirect method to estimate the twist in oscillating loops.
Le, H. Anh; Do, V. Nam
2018-03-01
We investigate the electronic and optical properties of twisted bilayer graphene with arbitrary twist angles θ . Our results are based on a method of evolving in time quantum states in lattice space. We propose an efficient scheme of sampling lattice nodes that helps to reduce significantly computational cost, particularly for tiny twist angles. We demonstrate the continuous variation of the density of states and the optical conductivity with respect to the twist angle. It indicates that the commensurability between the two graphene layers does not play an essential role in governing the electronic and optical properties. We point out that, for the twist angles roughly in the range 0 .1∘energy exhibits the typical W shape with a small peak locating at the Fermi energy. This peak is formed as the merging of two van Hove peaks and reflects the appearance of states strongly localized in the AA-like region of moiré zones. When decreasing the twist angle to zero, the W shape is gradually transformed to the U shape, which is seen as the behavior of the density of states in the limit of θ →0∘ .
Schambra, Uta B; Lewis, C Nicole; Harrison, Theresa A
2017-07-01
Debate continues on the merits of strictly limiting alcohol consumption during all of pregnancy, and whether "safe" consumption levels and/or times exist. Only a relatively few experimental studies have been conducted that limit the timing of exposure to specific events during development and the exposure level to one that might model sporadic, incidental drinking during pregnancy. In the present study, the effects of two acute gavage exposures to low and moderate levels of ethanol (peak blood ethanol concentrations (BEC) of 104 and 177mg/dl, respectively) either during gastrulation on gestational day (GD) 7 (at GD7:0h and GD7:4h) or during neurulation on GD8 (at GD8:6h and GD8:10h) on the spatial learning and memory abilities of adult mice in the radial arm maze (RAM) were examined. Mice were selected from a prenatal ethanol exposure (PAE) cohort that had been tested as neonates for their sensorimotor development (Schambra et al., 2015) and as juveniles and young adults for open field activity levels and emotionality (Schambra et al., 2016). Mice exposed on either of the two gestational days to acute, low or moderate levels of ethanol were deficient in overall performance in the RAM in adulthood. Importantly, mice in ethanol exposed groups took longer to reach criterion in the RAM, and many mice in these groups failed to do so after 48 trials when testing was terminated. Exposure to a low level of ethanol on either GD7 or GD8, or a moderate level on GD7, resulted in significant impairment in spatial reference (long-term) memory, while only mice exposed on GD7 to the low level of ethanol were significantly impaired in spatial working (short-term) memory. Mice exposed to the low ethanol level on either day had significantly shorter response latencies, which may reflect impairment of processes related to response inhibition or executive attention in these mice. For all measures, distributions of individual scores revealed a relatively small subset of mice in each PAE
Ten helical twist angles of B-DNA
Energy Technology Data Exchange (ETDEWEB)
Kabsch, W; Sander, C; Trifonov, E N
1982-01-01
On the assumption that the twist angles between adjacent base-pairs in the DNA molecule are additive a linear system of 40 equations was derived from experimental measurements of the total twist angles for different pieces of DNA of known sequences. This system of equations is found to be statistically consistent providing a solution for all ten possible twist angles of B-DNA by a least squares fitting procedure. Four of the calculated twist angles were not known before. The other six twist angles calculated are very close to the experimentally measured ones. The data used were obtained by the electrophoretic band-shift method, crystallography and nuclease digestion of DNA adsorbed to mica or Ca-phosphate surface. The validity of the principle of additivity of the twist angles implies that the angle between any particular two base-pairs is a function of only these base-pairs, independent of nearest neighbors.
Twisted Vanes Would Enhance Fuel/Air Mixing In Turbines
Nguyen, H. Lee; Micklow, Gerald J.; Dogra, Anju S.
1994-01-01
Computations of flow show performance of high-shear airblast fuel injector in gas-turbine engine enhanced by use of appropriately proportioned twisted (instead of flat) dome swirl vanes. Resultant more nearly uniform fuel/air mixture burns more efficiently, emitting smaller amounts of nitrogen oxides. Twisted-vane high-shear airblast injectors also incorporated into paint sprayers, providing advantages of low pressure drop characteristic of airblast injectors in general and finer atomization of advanced twisted-blade design.
Effective electrical and thermal conductivity of multifilament twisted superconductors
International Nuclear Information System (INIS)
Chechetkin, V.R.
2013-01-01
The effective electrical and thermal conductivity of composite wire with twisted superconducting filaments embedded into normal metal matrix is calculated using the extension of Bruggeman method. The resistive conductivity of superconducting filaments is described in terms of symmetric tensor, whereas the conductivity of a matrix is assumed to be isotropic and homogeneous. The dependence of the resistive electrical conductivity of superconducting filaments on temperature, magnetic field, and current density is implied to be parametric. The resulting effective conductivity tensor proved to be non-diagonal and symmetric. The non-diagonal transverse–longitudinal components of effective electrical conductivity tensor are responsible for the redistribution of current between filaments. In the limits of high and low electrical conductivity of filaments the transverse effective conductivity tends to that of obtained previously by Carr. The effective thermal conductivity of composite wires is non-diagonal and radius-dependent even for the isotropic and homogeneous thermal conductivities of matrix and filaments.
Twisted rudder for reducing fuel-oil consumption
Directory of Open Access Journals (Sweden)
Jung-Hun Kim
2014-09-01
Full Text Available Three twisted rudders fit for large container ships have been developed; 1 the Z-twisted rudder that is an asymmetry type taking into consideration incoming flow angles of the propeller slipstream, 2 the ZB-twisted rudder with a rudder bulb added onto the Z-twisted rudder, and 3 the ZB-F twisted rudder with a rudder fin attached to the ZB-twisted rudder. The twisted rudders have been designed computationally with the hydrodynamic characteristics in a self-propulsion condition in mind. The governing equation is the Navier-Stokes equations in an unsteady turbulent flow. The turbulence model applied is the Reynolds stress. The calculation was carried out in towing and self-propulsion conditions. The sliding mesh technique was employed to simulate the flow around the propeller. The speed performances of the ship with the twisted rudders were verified through model tests in a towing tank. The twisted versions showed greater performance driven by increased hull efficiency from less thrust deduction fraction and more effective wake fraction and decreased propeller rotating speed.
Higher twist contributions to deep-inelastic structure functions
International Nuclear Information System (INIS)
Bluemlein, J.; Boettcher, H.
2008-07-01
We report on a recent extraction of the higher twist contributions to the deep inelastic structure functions F ep,ed 2 (x,Q 2 ) in the large x region. It is shown that the size of the extracted higher twist contributions is strongly correlated with the higher order corrections applied to the leading twist part. A gradual lowering of the higher twist contributions going from NLO to N 4 LO is observed, where in the latter case only the leading large x terms were considered. (orig.)
Twisted sigma-model solitons on the quantum projective line
Landi, Giovanni
2018-04-01
On the configuration space of projections in a noncommutative algebra, and for an automorphism of the algebra, we use a twisted Hochschild cocycle for an action functional and a twisted cyclic cocycle for a topological term. The latter is Hochschild-cohomologous to the former and positivity in twisted Hochschild cohomology results into a lower bound for the action functional. While the equations for the critical points are rather involved, the use of the positivity and the bound by the topological term lead to self-duality equations (thus yielding twisted noncommutative sigma-model solitons, or instantons). We present explicit nontrivial solutions on the quantum projective line.
Bound states on the lattice with partially twisted boundary conditions
International Nuclear Information System (INIS)
Agadjanov, D.; Guo, F.-K.; Ríos, G.; Rusetsky, A.
2015-01-01
We propose a method to study the nature of exotic hadrons by determining the wave function renormalization constant Z from lattice simulations. It is shown that, instead of studying the volume-dependence of the spectrum, one may investigate the dependence of the spectrum on the twisting angle, imposing twisted boundary conditions on the fermion fields on the lattice. In certain cases, e.g., the case of the DK bound state which is addressed in detail, it is demonstrated that the partial twisting is equivalent to the full twisting up to exponentially small corrections.
Twist map, the extended Frenkel-Kontorova model and the devil's staircase
International Nuclear Information System (INIS)
Aubry, S.
1982-01-01
Exact results obtained on the discrete Frenkel Kontorova (FK) model and its extensions during the past few years are reviewed. These models are associated with area preserving twist maps of the cylinder (or a part of it) onto itself. The theorems obtained for the FK model thus yields new theorems for the twist maps. The exact structure of the ground-states which are either commensurate or incommensurate and assert the existence of elementary discommensurations under certain necessary and sufficient conditions is described. Necessary conditions for the trajectories to represent metastable configurations, which can be chaotic, are given. The existence of a finite Peierl Nabarro barrier for elementary discommensurations is connected with a property of non-integrability of the twist map. The existence of KAM tori corresponds to undefectible incommensurate ground-states and a theorem is given which asserts that when the phenon spectrum of an incommensurate ground-state exhibits a finite gap, then the corresponding trajectory is dense on a Cantor set with zero measure length. These theorems, when applied to the initial FK model, allows one to prove the existence of the transition by breaking of analyticity for the incommensurate structures when the parameter which describes the discrepancy of the model to the integrable limit varies. Finally, we describe a theorem proving the existence of a devil's staircase for the variation curve of the atomic mean distance versus a chemical potential, for certain properties of the twist map which are generally satisfied
Twisting and Writhing with George Ellery Hale
Canfield, Richard C.
2013-06-01
Early in his productive career in astronomy, George Ellery Hale developed innovative solar instrumentation that allowed him to make narrow-band images. Among the solar phenomena he discovered were sunspot vortices, which he attributed to storms akin to cyclones in our own atmosphere. Using the concept of magnetic helicity, physicists and mathematicians describe the topology of magnetic fields, including twisting and writhing. Our contemporary understanding of Hale's vortices as a consequence of large-scale twist in sunspot magnetic fields hinges on a key property of helicity: conservation. I will describe the critical role that this property plays, when applied to twist and writhe, in a fundamental aspect of global solar magnetism: the hemispheric and solar cycle dependences of active region electric currents with respect to magnetic fields. With the advent of unbroken sequences of high-resolution magnetic images, such as those presently available from the Helioseismic and Magnetic Imager on Solar Dynamics Observatory, the flux of magnetic helicity through the photosphere can be observed quantitatively. As magnetic flux tubes buoy up through the convection zone, buffeted and shredded by turbulence, they break up into fragments by repeated random bifurcation. We track these rising flux fragments in the photosphere, and calculate the flux of energy and magnetic helicity there. Using a quantitative model of coronal currents, we also track connections between these fragments to calculate the energy and magnetic helicity stored at topological interfaces that are in some ways analogous to the storage of stress at faults in the Earth's crust. Comparison of these values to solar flares and interplanetary coronal mass ejections implies that this is the primary storage mechanism for energy and magnetic helicity released in those phenomena, and suggests a useful tool for quantitative prediction of geomagnetic storms.
Twisted Polynomials and Forgery Attacks on GCM
DEFF Research Database (Denmark)
Abdelraheem, Mohamed Ahmed A. M. A.; Beelen, Peter; Bogdanov, Andrey
2015-01-01
Polynomial hashing as an instantiation of universal hashing is a widely employed method for the construction of MACs and authenticated encryption (AE) schemes, the ubiquitous GCM being a prominent example. It is also used in recent AE proposals within the CAESAR competition which aim at providing...... in an improved key recovery algorithm. As cryptanalytic applications of our twisted polynomials, we develop the first universal forgery attacks on GCM in the weak-key model that do not require nonce reuse. Moreover, we present universal weak-key forgeries for the nonce-misuse resistant AE scheme POET, which...
Optical twists in phase and amplitude
DEFF Research Database (Denmark)
Daria, Vincent R.; Palima, Darwin; Glückstad, Jesper
2011-01-01
where both phase and amplitude express a helical profile as the beam propagates in free space. Such a beam can be accurately referred to as an optical twister. We characterize optical twisters and demonstrate their capacity to induce spiral motion on particles trapped along the twisters’ path. Unlike LG...... beams, the far field projection of the twisted optical beam maintains a high photon concentration even at higher values of topological charge. Optical twisters have therefore profound applications to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps...
NMSBA - Twist Resist - Rotational Exercise Module
Energy Technology Data Exchange (ETDEWEB)
Walker, Aaron [Twist Resist, Albuquerque, NM (United States); Reece, Blake D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Berger, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Guido, Steven Frank [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Linker, Taylor [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-08-01
This report contains a summary of the work completed to develop a modular, rotational exercise device. In the report are images, diagrams, and explanations of the efforts contributed to the project since its inception. The purpose of this document is to provide a walk-through of the progress on this project, from the initial design concepts to the final design and work done, so that the customer (Twist Resist), or individuals/firms who work on this project in the future will have a springboard of ideas/concepts to work from.
On reflection algebras and twisted Yangians
International Nuclear Information System (INIS)
Doikou, Anastasia
2005-01-01
It is well known that integrable models associated to rational R matrices give rise to certain non-Abelian symmetries known as Yangians. Analogously boundary symmetries arise when general but still integrable boundary conditions are implemented, as originally argued by Delius, Mackay, and Short from the field theory point of view, in the context of the principal chiral model on the half-line. In the present study we deal with a discrete quantum mechanical system with boundaries, that is the N site gl(n) open quantum spin chain. In particular, the open spin chain with two distinct types of boundary condition known as soliton preserving and soliton nonpreserving is considered. For both types of boundaries we present a unified framework for deriving the corresponding boundary nonlocal charges directly at the quantum level. The nonlocal charges are simply coproduct realizations of particular boundary quantum algebras called boundary or twisted Yangians, depending on the choice of boundary conditions. Finally, with the help of linear intertwining relations between the solutions of the reflection equation and the generators of the boundary or twisted Yangians we are able to exhibit the exact symmetry of the open spin chain, namely we show that a number of the boundary nonlocal charges are in fact conserved quantities
How the embryonic brain tube twists
Chen, Zi; Guo, Qiaohang; Forsch, Nickolas; Taber, Larry
2014-03-01
During early development, the tubular brain of the chick embryo undergoes a combination of progressive ventral bending and rightward torsion. This deformation is one of the major organ-level symmetry-breaking events in development. Available evidence suggests that bending is caused by differential growth, but the mechanism for torsion remains poorly understood. Since the heart almost always loops in the same direction that the brain twists, researchers have speculated that heart looping affects the direction of brain torsion. However, direct evidence is virtually nonexistent, nor is the mechanical origin of such torsion understood. In our study, experimental perturbations show that the bending and torsional deformations in the brain are coupled and that the vitelline membrane applies an external load necessary for torsion to occur. In addition, the asymmetry of the looping heart gives rise to the chirality of the twisted brain. A computational model is used to interpret these findings. Our work clarifies the mechanical origins of brain torsion and the associated left-right asymmetry, reminiscent of D'Arcy Thompson's view of biological form as ``diagram of forces''.
Strong CP, flavor, and twisted split fermions
International Nuclear Information System (INIS)
Harnik, Roni; Perez, Gilad; Schwartz, Matthew D.; Shirman, Yuri
2005-01-01
We present a natural solution to the strong CP problem in the context of split fermions. By assuming CP is spontaneously broken in the bulk, a weak CKM phase is created in the standard model due to a twisting in flavor space of the bulk fermion wavefunctions. But the strong CP phase remains zero, being essentially protected by parity in the bulk and CP on the branes. As always in models of spontaneous CP breaking, radiative corrections to theta bar from the standard model are tiny, but even higher dimension operators are not that dangerous. The twisting phenomenon was recently shown to be generic, and not to interfere with the way that split fermions naturally weaves small numbers into the standard model. It follows that out approach to strong CP is compatible with flavor, and we sketch a comprehensive model. We also look at deconstructed version of this setup which provides a viable 4D model of spontaneous CP breaking which is not in the Nelson-Barr class. (author)
Gaussian tunneling model of c-axis twist Josephson junctions
International Nuclear Information System (INIS)
Bille, A.; Klemm, R.A.; Scharnberg, K.
2001-01-01
We calculate the critical current density J c J ((var p hi) 0 ) for Josephson tunneling between identical high-temperature superconductors twisted an angle (var p hi) 0 about the c axis. Regardless of the shape of the two-dimensional Fermi surface and for very general tunneling matrix elements, an order parameter (OP) with general d-wave symmetry leads to J c J (π/4)=0. This general result is inconsistent with the data of Li et al. [Phys. Rev. Lett. 83, 4160 (1999)] on Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212), which showed J c J to be independent of (var p hi) 0 . If the momentum parallel to the barrier is conserved in the tunneling process, J c J should vary substantially with the twist angle (var p hi) 0 when the tight-binding Fermi surface appropriate for Bi2212 is taken into account, even if the OP is completely isotropic. We quantify the degree of momentum nonconservation necessary to render J c J ((var p hi) 0 ) constant within experimental error for a variety of pair states by interpolating between the coherent and incoherent limits using five specific models to describe the momentum dependence of the tunneling matrix element squared. From the data of Li et al., we conclude that the c-axis tunneling in Bi2212 must be very nearly incoherent, and that the OP must have a nonvanishing Fermi-surface average for T c . We further show that the apparent conventional sum-rule violation observed by Basov et al. [Science 283, 49 (1999)] can be consistent with such strongly incoherent c-axis tunneling.
Quadratic Twists of Rigid Calabi–Yau Threefolds Over
DEFF Research Database (Denmark)
Gouvêa, Fernando Q.; Kiming, Ian; Yui, Noriko
2013-01-01
of weight 4 on some Γ 0(N). We show that quadratic twisting of a threefold corresponds to twisting the attached newform by quadratic characters and illustrate with a number of obvious and not so obvious examples. The question is motivated by the deeper question of which newforms of weight 4 on some Γ 0(N...
Bend-twist coupling potential of wind turbine blades
DEFF Research Database (Denmark)
Fedorov, Vladimir; Berggreen, Christian
2014-01-01
-twist coupling magnitude of up to 0.2 is feasible to achieve in the baseline blade structure made of glass-fiber reinforced plastics. Further, by substituting the glass-fibers with carbon-fibers the coupling effect can be increased to 0.4. Additionally, the effect of introduction of bend-twist coupling...
A twisted generalization of Novikov-Poisson algebras
Yau, Donald
2010-01-01
Hom-Novikov-Poisson algebras, which are twisted generalizations of Novikov-Poisson algebras, are studied. Hom-Novikov-Poisson algebras are shown to be closed under tensor products and several kinds of twistings. Necessary and sufficient conditions are given under which Hom-Novikov-Poisson algebras give rise to Hom-Poisson algebras.
Enhancement of heat transfer using varying width twisted tape inserts
African Journals Online (AJOL)
user
enhancement of heat transfer with twisted tape inserts as compared to plain ... studies for heat transfer and pressure drop of laminar flow in horizontal tubes ... flow in rectangular and square plain ducts and ducts with twisted-tape inserts .... presence of the insert in the pipe causes resistance to flow and increases turbulence.
Duality and braiding in twisted quantum field theory
International Nuclear Information System (INIS)
Riccardi, Mauro; Szabo, Richard J.
2008-01-01
We re-examine various issues surrounding the definition of twisted quantum field theories on flat noncommutative spaces. We propose an interpretation based on nonlocal commutative field redefinitions which clarifies previously observed properties such as the formal equivalence of Green's functions in the noncommutative and commutative theories, causality, and the absence of UV/IR mixing. We use these fields to define the functional integral formulation of twisted quantum field theory. We exploit techniques from braided tensor algebra to argue that the twisted Fock space states of these free fields obey conventional statistics. We support our claims with a detailed analysis of the modifications induced in the presence of background magnetic fields, which induces additional twists by magnetic translation operators and alters the effective noncommutative geometry seen by the twisted quantum fields. When two such field theories are dual to one another, we demonstrate that only our braided physical states are covariant under the duality
Analysis list: Twist1 [Chip-atlas[Archive
Lifescience Database Archive (English)
Full Text Available Twist1 Embryo,Neural + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Tw...ist1.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Twist1.5.tsv http://dbarchive.biosciencedbc....jp/kyushu-u/mm9/target/Twist1.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Twist1.Embryo.tsv,http://dbarchive.bioscien...cedbc.jp/kyushu-u/mm9/colo/Twist1.Neural.tsv http://dbarchive.bioscience...dbc.jp/kyushu-u/mm9/colo/Embryo.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Neural.gml ...
On the performance analysis of Savonius rotor with twisted blades
Energy Technology Data Exchange (ETDEWEB)
Saha, U.K.; Rajkumar, M. Jaya [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati-781 039 (India)
2006-09-15
The present investigation is aimed at exploring the feasibility of twisted bladed Savonius rotor for power generation. The twisted blade in a three-bladed rotor system has been tested in a low speed wind tunnel, and its performance has been compared with conventional semicircular blades (with twist angle of 0{sup o}). Performance analysis has been made on the basis of starting characteristics, static torque and rotational speed. Experimental evidence shows the potential of the twisted bladed rotor in terms of smooth running, higher efficiency and self-starting capability as compared to that of the conventional bladed rotor. Further experiments have been conducted in the same setup to optimize the twist angle. (author)
New Values of Cross-Talk Parameters for Twisted Pair Model
Milos Kozak; Lukas Cepa; Jiri Vodrazka
2010-01-01
Near-end Crosstalk (NEXT) and Far-end Crosstalk (FEXT) of unshielded twisted pair (UTP) cable are the main factors limiting the information capacity in data transmission. Crosstalk depends mostly on the frequency. Frequency dependent transfer functions and crosstalk attenuation may be obtained by measurement, but for the analytical description of the transmission channel's parameters is useful to define functions modelling the crosstalk. The paper describes the measuri...
Bianisotropic metamaterials based on twisted asymmetric crosses
International Nuclear Information System (INIS)
Reyes-Avendaño, J A; Sampedro, M P; Juárez-Ruiz, E; Pérez-Rodríguez, F
2014-01-01
The effective bianisotropic response of 3D periodic metal-dielectric structures, composed of crosses with asymmetrically-cut wires, is investigated within a general homogenization theory using the Fourier formalism and the form-factor division approach. It is found that the frequency dependence of the effective permittivity for a system of periodically-repeated layers of metal crosses exhibits two strong resonances, whose separation is due to the cross asymmetry. Besides, bianisotropic metamaterials, having a base of four twisted asymmetric crosses, are proposed. The designed metamaterials possess negative refractive index at frequencies determined by the cross asymmetry, the gap between the arms of adjacent crosses lying on the same plane, and the type of Bravais lattice. (papers)
Band engineering in twisted molybdenum disulfide bilayers
Zhao, Yipeng; Liao, Chengwei; Ouyang, Gang
2018-05-01
In order to explore the theoretical relationship between interlayer spacing, interaction and band offset at the atomic level in vertically stacked two-dimensional (2D) van der Waals (vdW) structures, we propose an analytical model to address the evolution of interlayer vdW coupling with random stacking configurations in MoS2 bilayers based on the atomic-bond-relaxation correlation mechanism. We found that interlayer spacing changes substantially with respect to the orientations, and the bandgap increases from 1.53 eV (AB stacking) to 1.68 eV (AA stacking). Our results reveal that the evolution of interlayer vdW coupling originates from the interlayer interaction, leading to interlayer separations and electronic properties changing with stacking configurations. Our predictions constitute a demonstration of twist engineering the band shift in the emergent class of 2D crystals, transition-metal dichalcogenides.
Unusual presentation of twisted ovarian cyst
Directory of Open Access Journals (Sweden)
Vineet V Mishra
2016-01-01
Full Text Available Ovarian torsion (also termed as adnexal torsion refers to partial or complete rotation of the ovary and a portion of fallopian tube along its supplying vascular pedicle. It occurs commonly in reproductive age group; more on the right side (60% and often presents with acute lower abdominal pain lasting for few hours and up to 24 h, accounting for 2.7% of acute gynecological conditions. It is one of the devastating conditions, hampering blood supply of ovary which may lead to total necrosis of ovarian tissue and complications, if not diagnosed and managed in time. Hence, we present a case on a twisted ovarian cyst in postmenopausal woman with unusual symptomatology leading to delayed diagnosis and loss of an ovary.
International Nuclear Information System (INIS)
Obregon, Octavio; Quevedo, Hernando; Ryan, Michael P.
2004-01-01
We construct a family of time and angular dependent, regular S-brane solutions which corresponds to a simple analytical continuation of the Zipoy-Voorhees 4-dimensional vacuum spacetime. The solutions are asymptotically flat and turn out to be free of singularities without requiring a twist in space. They can be considered as the simplest non-singular generalization of the singular S0-brane solution. We analyze the properties of a representative of this family of solutions and show that it resembles to some extent the asymptotic properties of the regular Kerr S-brane. The R-symmetry corresponds, however, to the general lorentzian symmetry. Several generalizations of this regular solution are derived which include a charged S-brane and an additional dilatonic field. (author)
Three-point correlator of twist-2 light-ray operators in N=4 SYM in BFKL approximation
International Nuclear Information System (INIS)
Balitsky, Ian; Sobko, Evgeny
2015-11-01
We present calculation of the correlation function of three twist-2 operators in the BFKL limit. The calculation is performed in N=4 SYM but the result is valid in other gauge theories such as QCD. The obtained leading order structure constant is exact for any number of colors.
Dynamical twisted mass fermions and baryon spectroscopy
International Nuclear Information System (INIS)
Drach, V.
2010-06-01
The aim of this work is an ab initio computation of the baryon masses starting from quantum chromodynamics (QCD). This theory describes the interaction between quarks and gluons and has been established at high energy thanks to one of its fundamental properties: the asymptotic freedom. This property predicts that the running coupling constant tends to zero at high energy and thus that perturbative expansions in the coupling constant are justified in this regime. On the contrary the low energy dynamics can only be understood in terms of a non perturbative approach. To date, the only known method that allows the computation of observables in this regime together with a control of its systematic effects is called lattice QCD. It consists in formulating the theory on an Euclidean space-time and to evaluating numerically suitable functional integrals. First chapter is an introduction to the QCD in the continuum and on a discrete space time. The chapter 2 describes the formalism of maximally twisted fermions used in the European Twisted Mass (ETM) collaboration. The chapter 3 deals with the techniques needed to build hadronic correlator starting from gauge configuration. We then discuss how we determine hadron masses and their statistical errors. The numerical estimation of functional integral is explained in chapter 4. It is stressed that it requires sophisticated algorithm and massive parallel computing on Blue-Gene type architecture. Gauge configuration production is an important part of the work realized during my Ph.D. Chapter 5 is a critical review on chiral perturbation theory in the baryon sector. The two last chapter are devoted to the analysis in the light and strange baryon sector. Systematics and chiral extrapolation are extensively discussed. (author)
Bioinspired twisted composites based on Bouligand structures
Pinto, F.; Iervolino, O.; Scarselli, G.; Ginzburg, D.; Meo, M.
2016-04-01
The coupling between structural support and protection makes biological systems an important source of inspiration for the development of advanced smart composite structures. In particular, some particular material configurations can be implemented into traditional composites in order to improve their impact resistance and the out-of-plane properties, which represents one of the major weakness of commercial carbon fibres reinforced polymers (CFRP) structures. Based on this premise, a three-dimensional twisted arrangement shown in a vast multitude of biological systems (such as the armoured cuticles of Scarabei, the scales of Arapaima Gigas and the smashing club of Odontodactylus Scyllarus) has been replicated to develop an improved structural material characterised by a high level of in-plane isotropy and a higher interfacial strength generated by the smooth stiffness transition between each layer of fibrils. Indeed, due to their intrinsic layered nature, interlaminar stresses are one of the major causes of failure of traditional CFRP and are generated by the mismatch of the elastic properties between plies in a traditional laminate. Since the energy required to open a crack or a delamination between two adjacent plies is due to the difference between their orientations, the gradual angle variation obtained by mimicking the Bouligand Structures could improve energy absorption and the residual properties of carbon laminates when they are subjected to low velocity impact event. Two different bioinspired laminates were manufactured following a double helicoidal approach and a rotational one and were subjected to a complete test campaign including low velocity impact loading and compared to a traditional quasi-isotropic panel. Fractography analysis via X-Ray tomography was used to understand the mechanical behaviour of the different laminates and the residual properties were evaluated via Compression After Impact (CAI) tests. Results confirmed that the biological
Twisted boundary states in c=1 coset conformal field theories
International Nuclear Information System (INIS)
Ishikawa, Hiroshi; Yamaguchi, Atsushi
2003-01-01
We study the mutual consistency of twisted boundary conditions in the coset conformal field theory G/H. We calculate the overlap of the twisted boundary states of G/H with the untwisted ones, and show that the twisted boundary states are consistently defined in the charge-conjugation modular invariant. The overlap of the twisted boundary states is expressed by the branching functions of a twisted affine Lie algebra. As a check of our argument, we study the diagonal coset theory so(2n) 1 +so(2n) 1 /so(2n) 2 , which is equivalent to the orbifold S 1 /Z 2 at a particular radius. We construct the boundary states twisted by the automorphisms of the unextended Dynkin diagram of so(2n), and show their mutual consistency by identifying their counterpart in the orbifold. For the triality of so(8), the twisted states of the coset theory correspond to neither the Neumann nor the Dirichlet boundary states of the orbifold and yield conformal boundary states that preserve only the Virasoro algebra. (author)
Conical twist fields and null polygonal Wilson loops
Castro-Alvaredo, Olalla A.; Doyon, Benjamin; Fioravanti, Davide
2018-06-01
Using an extension of the concept of twist field in QFT to space-time (external) symmetries, we study conical twist fields in two-dimensional integrable QFT. These create conical singularities of arbitrary excess angle. We show that, upon appropriate identification between the excess angle and the number of sheets, they have the same conformal dimension as branch-point twist fields commonly used to represent partition functions on Riemann surfaces, and that both fields have closely related form factors. However, we show that conical twist fields are truly different from branch-point twist fields. They generate different operator product expansions (short distance expansions) and form factor expansions (large distance expansions). In fact, we verify in free field theories, by re-summing form factors, that the conical twist fields operator product expansions are correctly reproduced. We propose that conical twist fields are the correct fields in order to understand null polygonal Wilson loops/gluon scattering amplitudes of planar maximally supersymmetric Yang-Mills theory.
B{sub K}-parameter from N{sub f}=2 twisted mass lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Constantinou, M. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Dimopoulos, P. [Roma Univ. (Italy). Dipt. di Fisica; Frezzotti, R. [Roma ' ' Tor Vergata' ' Univ. (Italy). Dipt. di Fisica; INFN, Rome (IT). Dipt. di Fisica] (and others)
2011-01-07
We present an unquenched N{sub f} = 2 lattice computation of the B{sub K} parameter which controls K{sup 0}- anti K{sup 0} oscillations. A partially quenched setup is employed with two maximally twisted dynamical (sea) light Wilson quarks, and valence quarks of both the maximally twisted and the Osterwalder-Seiler variety. Suitable combinations of these two kinds of valence quarks lead to a lattice definition of the B{sub K} parameter which is both multiplicatively renormalizable and O(a) improved. Employing the non-perturbative RI-MOM scheme, in the continuum limit and at the physical value of the pion mass we get B{sup RGI}{sub K}=0.729{+-}0.030, a number well in line with the existing quenched and unquenched determinations. (orig.)
Some exact computations on the twisted butterfly state in string field theory
International Nuclear Information System (INIS)
Okawa, Yuji
2004-01-01
The twisted butterfly state solves the equation of motion of vacuum string field theory in the singular limit. The finiteness of the energy density of the solution is an important issue, but possible conformal anomaly resulting from the twisting has prevented us from addressing this problem. We present a description of the twisted regulated butterfly state in terms of a conformal field theory with a vanishing central charge which consists of the ordinary bc ghosts and a matter system with c=26. Various quantities relevant to vacuum string field theory are computed exactly using this description. We find that the energy density of the solution can be finite in the limit, but the finiteness depends on the sub leading structure of vacuum string field theory. We further argue, contrary to our previous expectation, that contributions from sub leading terms in the kinetic term to the energy density can be of the same order as the contribution from the leading term which consists of the midpoint ghost insertion. (author)
Flavour symmetry restoration and kaon weak matrix elements in quenched twisted mass QCD
Dimopoulos, P; Palombi, Filippo; Peña, C; Sint, S; Vladikas, A
2007-01-01
We simulate two variants of quenched twisted mass QCD (tmQCD), with degenerate Wilson quarks of masses equal to or heavier than half the strange quark mass. We use Ward identities in order to measure the twist angles of the theory and thus check the quality of the tuning of mass parameters to a physics condition which stays constant as the lattice spacing is varied. Flavour symmetry breaking in tmQCD is studied in a framework of two fully twisted and two standard Wilson quark flavours, tuned to be degenerate in the continuum. Comparing pseudoscalar masses, obtained from connected quark diagrams made of tmQCD and/or standard Wilson quark propagators, we confirm that flavour symmetry breaking effects, which are at most 5%, decrease as we approach the continuum limit. We also compute the pseudoscalar decay constant in the continuum limit, with reduced systematics. As a consequence of improved tuning of the mass parameters at $\\beta = 6.1$, we reanalyse our previous $B_K$ results. Our main phenomenological findin...
Conformal invariance and pion wave functions of nonleading twist
International Nuclear Information System (INIS)
Braun, V.M.; Filyanov, I.E.
1989-01-01
The restrictions are studied for the general structure of pion wave functions of twist 3 and twist 4 imposed by the conformal symmetry and the equations of motion. A systematic expansion of wave functions in the conformal spin is built and the first order corrections to asymptotic formulae are calculated by the QCD sum rule method. In particular, we have found a multiplicatively renormalizable contribution into the two-particle wave function of twist 4 which cannot be expanded in a finite set of Gegenbauer polynomials. 19 refs.; 5 figs
Quantum communication through a spin ring with twisted boundary conditions
International Nuclear Information System (INIS)
Bose, S.; Jin, B.-Q.; Korepin, V.E.
2005-01-01
We investigate quantum communication between the sites of a spin ring with twisted boundary conditions. Such boundary conditions can be achieved by a magnetic flux through the ring. We find that a nonzero twist can improve communication through finite odd-numbered rings and enable high-fidelity multiparty quantum communication through spin rings (working near perfectly for rings of five and seven spins). We show that in certain cases, the twist results in the complete blockage of quantum-information flow to a certain site of the ring. This effect can be exploited to interface and entangle a flux qubit and a spin qubit without embedding the latter in a magnetic field
TWIST1 promotes invasion through mesenchymal change in human glioblastoma
Directory of Open Access Journals (Sweden)
Wakimoto Hiroaki
2010-07-01
Full Text Available Abstract Background Tumor cell invasion into adjacent normal brain is a mesenchymal feature of GBM and a major factor contributing to their dismal outcomes. Therefore, better understandings of mechanisms that promote mesenchymal change in GBM are of great clinical importance to address invasion. We previously showed that the bHLH transcription factor TWIST1 which orchestrates carcinoma metastasis through an epithelial mesenchymal transition (EMT is upregulated in GBM and promotes invasion of the SF767 GBM cell line in vitro. Results To further define TWIST1 functions in GBM we tested the impact of TWIST1 over-expression on invasion in vivo and its impact on gene expression. We found that TWIST1 significantly increased SNB19 and T98G cell line invasion in orthotopic xenotransplants and increased expression of genes in functional categories associated with adhesion, extracellular matrix proteins, cell motility and locomotion, cell migration and actin cytoskeleton organization. Consistent with this TWIST1 reduced cell aggregation, promoted actin cytoskeletal re-organization and enhanced migration and adhesion to fibronectin substrates. Individual genes upregulated by TWIST1 known to promote EMT and/or GBM invasion included SNAI2, MMP2, HGF, FAP and FN1. Distinct from carcinoma EMT, TWIST1 did not generate an E- to N-cadherin "switch" in GBM cell lines. The clinical relevance of putative TWIST target genes SNAI2 and fibroblast activation protein alpha (FAP identified in vitro was confirmed by their highly correlated expression with TWIST1 in 39 human tumors. The potential therapeutic importance of inhibiting TWIST1 was also shown through a decrease in cell invasion in vitro and growth of GBM stem cells. Conclusions Together these studies demonstrated that TWIST1 enhances GBM invasion in concert with mesenchymal change not involving the canonical cadherin switch of carcinoma EMT. Given the recent recognition that mesenchymal change in GBMs is
Twisted photon entanglement through turbulent air across Vienna.
Krenn, Mario; Handsteiner, Johannes; Fink, Matthias; Fickler, Robert; Zeilinger, Anton
2015-11-17
Photons with a twisted phase front can carry a discrete, in principle, unbounded amount of orbital angular momentum (OAM). The large state space allows for complex types of entanglement, interesting both for quantum communication and for fundamental tests of quantum theory. However, the distribution of such entangled states over large distances was thought to be infeasible due to influence of atmospheric turbulence, indicating a serious limitation on their usefulness. Here we show that it is possible to distribute quantum entanglement encoded in OAM over a turbulent intracity link of 3 km. We confirm quantum entanglement of the first two higher-order levels (with OAM=± 1ħ and ± 2ħ). They correspond to four additional quantum channels orthogonal to all that have been used in long-distance quantum experiments so far. Therefore, a promising application would be quantum communication with a large alphabet. We also demonstrate that our link allows access to up to 11 quantum channels of OAM. The restrictive factors toward higher numbers are technical limitations that can be circumvented with readily available technologies.
Blossier, BenoÃ®t.; Brinet, Mariane; Guichon, Pierre; Morénas, Vincent; Pène, Olivier; Rodríguez-Quintero, Jose; Zafeiropoulos, Savvas
2015-06-01
We present a precise nonperturbative determination of the renormalization constants in the mass independent RI'-MOM scheme. The lattice implementation uses the Iwasaki gauge action and four degenerate dynamical twisted-mass fermions. The gauge configurations are provided by the ETM Collaboration. Renormalization constants for scalar, pseudoscalar, vector and axial operators, as well as the quark propagator renormalization, are computed at three different values of the lattice spacing, two volumes and several twisted-mass parameters. The method we developed allows for a precise cross-check of the running, thanks to the particular proper treatment of hypercubic artifacts. Results for the twist-2 operator O44 are also presented.
Enhancement of heat transfer using varying width twisted tape inserts
African Journals Online (AJOL)
International Journal of Engineering, Science and Technology ... experimental investigations of the augmentation of turbulent flow heat transfer in a horizontal tube by means of varying width twisted tape inserts with air as the working fluid.
Periodic solutions of asymptotically linear Hamiltonian systems without twist conditions
Energy Technology Data Exchange (ETDEWEB)
Cheng Rong [Coll. of Mathematics and Physics, Nanjing Univ. of Information Science and Tech., Nanjing (China); Dept. of Mathematics, Southeast Univ., Nanjing (China); Zhang Dongfeng [Dept. of Mathematics, Southeast Univ., Nanjing (China)
2010-05-15
In dynamical system theory, especially in many fields of applications from mechanics, Hamiltonian systems play an important role, since many related equations in mechanics can be written in an Hamiltonian form. In this paper, we study the existence of periodic solutions for a class of Hamiltonian systems. By applying the Galerkin approximation method together with a result of critical point theory, we establish the existence of periodic solutions of asymptotically linear Hamiltonian systems without twist conditions. Twist conditions play crucial roles in the study of periodic solutions for asymptotically linear Hamiltonian systems. The lack of twist conditions brings some difficulty to the study. To the authors' knowledge, very little is known about the case, where twist conditions do not hold. (orig.)
The geometric Langlands twist in five and six dimensions
International Nuclear Information System (INIS)
Bak, Dongsu; Gustavsson, Andreas
2015-01-01
Abelian 6d (2,0) theory has SO(5) R symmetry. We twist this theory by identifying the R symmetry group with the SO(5) subgroup of the SO(1,5) Lorentz group. This twisted theory can be put on any five-manifold M, times R, while preserving one scalar supercharge. We subsequently assume the existence of one unit normalized Killing vector field on M, and we find a corresponding SO(4) twist that preserves two supercharges and is a generalization of the geometric Langlands twist of 4d SYM. We generalize the story to non-Abelian gauge group for the corresponding 5d SYM theories on M. We derive a vanishing theorem for BPS contact instantons by identifying the 6d potential energy and its BPS bound, in the 5d theory. To this end we need to perform a Wick rotation that complexifies the gauge field.
Static-light meson masses from twisted mass lattice QCD
International Nuclear Information System (INIS)
Jansen, Karl; Michael, Chris; Shindler, Andrea; Wagner, Marc
2008-08-01
We compute the static-light meson spectrum using two-flavor Wilson twisted mass lattice QCD. We have considered five different values for the light quark mass corresponding to 300 MeV PS S mesons. (orig.)
Flux Density through Guides with Microstructured Twisted Clad DB Medium
Directory of Open Access Journals (Sweden)
M. A. Baqir
2014-01-01
Full Text Available The paper deals with the study of flux density through a newly proposed twisted clad guide containing DB medium. The inner core and the outer clad sections are usual dielectrics, and the introduced twisted windings at the core-clad interface are treated under DB boundary conditions. The pitch angle of twist is supposed to greatly contribute towards the control over the dispersion characteristics of the guide. The eigenvalue equation for the guiding structure is deduced, and the analytical investigations are made to explore the propagation patterns of flux densities corresponding to the sustained low-order hybrid modes under the situation of varying pitch angles. The emphasis has been put on the effects due to the DB twisted pitch on the propagation of energy flux density through the guide.
Õnnetu saatusega Oliver Twist Polanski meelevallas / Andres Laasik
Laasik, Andres, 1960-2016
2005-01-01
Mängufilm Charles Dickensi romaani järgi "Oliver Twist" : stsenarist Ronald Harwood : režissöör Roman Polanski : nimiosas Barney Clark, Fagin - Ben Kingsley : Suurbritannia - Tšehhi - Prantsusmaa - Itaalia 2005
Study of twist boundaries in aluminium. Structure and intergranular diffusion
International Nuclear Information System (INIS)
Lemuet, Daniel
1981-01-01
This research thesis addresses the study of grain boundaries in oriented crystals, and more particularly the systematic calculation of intergranular structures and energies of twist boundaries of <001> axis in aluminium, the determination of intergranular diffusion coefficients of zinc in a set of twist bi-crystals of same axis encompassing a whole range of disorientations, and the search for a correlation between these experimental results and calculated structures
'Twisted' strings and higher level Kac-Moody representations
International Nuclear Information System (INIS)
Horvath, Z.; Palla, L.
1989-01-01
Using an orbifold-like construction the twisted sector of a closed string moving on GxG (with G simply laced) is determined. A level-two G current operating there is constructed explicitly. The decomposition of the twisted sector into products between appropriate conformal and level-two G representations is given if 2 rank G-2 dim G/(2+g)<1. (orig.)
New look at the dynamics of twisted accretion disks
International Nuclear Information System (INIS)
Hatchett, S.P.; Begelman, M.C.; Sarazin, C.L.
1981-01-01
We reexamine the dynamic response of a thin, accretion disk to twisting torques, guided by the earlier analyses by Bardeen and Petterson. We make several corrections to this earlier work, and present a new version of the twist equations consistent with their physical assumptions. By describing the distortion of the disk in terms Cartesian direction cosines rather than the Euler angles used by the earlier authors, we are able to transform the twist equations from a pair of coupled, nonlinear, partial differential equations to a single, linear, complex one. We write down formulae for the external twisting torques likley to be encountered in astrophysic, and we show that even with these driving torques our twist equation remains linear. We find exact, analytic solutions for steady state structure of a disk subject to Lense-Thirring torques by a nonaligned central Kerr black hole and also for the time-dependent problem of the structure of a slaved disk with its oscillating boundary conditions. Finally, we discuss the stability of disks against twisting modes and show that undriven disks and disks subject to time-independent driving torques are stable
Twisting short dsDNA with applied tension
Zoli, Marco
2018-02-01
The twisting deformation of mechanically stretched DNA molecules is studied by a coarse grained Hamiltonian model incorporating the fundamental interactions that stabilize the double helix and accounting for the radial and angular base pair fluctuations. The latter are all the more important at short length scales in which DNA fragments maintain an intrinsic flexibility. The presented computational method simulates a broad ensemble of possible molecule conformations characterized by a specific average twist and determines the energetically most convenient helical twist by free energy minimization. As this is done for any external load, the method yields the characteristic twist-stretch profile of the molecule and also computes the changes in the macroscopic helix parameters i.e. average diameter and rise distance. It is predicted that short molecules under stretching should first over-twist and then untwist by increasing the external load. Moreover, applying a constant load and simulating a torsional strain which over-twists the helix, it is found that the average helix diameter shrinks while the molecule elongates, in agreement with the experimental trend observed in kilo-base long sequences. The quantitative relation between percent relative elongation and superhelical density at fixed load is derived. The proposed theoretical model and computational method offer a general approach to characterize specific DNA fragments and predict their macroscopic elastic response as a function of the effective potential parameters of the mesoscopic Hamiltonian.
Scanning tunneling microscopy and spectroscopy of twisted trilayer graphene
Zuo, Wei-Jie; Qiao, Jia-Bin; Ma, Dong-Lin; Yin, Long-Jing; Sun, Gan; Zhang, Jun-Yang; Guan, Li-Yang; He, Lin
2018-01-01
Twist, as a simple and unique degree of freedom, could lead to enormous novel quantum phenomena in bilayer graphene. A small rotation angle introduces low-energy van Hove singularities (VHSs) approaching the Fermi level, which result in unusual correlated states in the bilayer graphene. It is reasonable to expect that the twist could also affect the electronic properties of few-layer graphene dramatically. However, such an issue has remained experimentally elusive. Here, by using scanning tunneling microscopy/spectroscopy (STM/STS), we systematically studied a twisted trilayer graphene (TTG) with two different small twist angles between adjacent layers. Two sets of VHSs, originating from the two twist angles, were observed in the TTG, indicating that the TTG could be simply regarded as a combination of two different twisted bilayers of graphene. By using high-resolution STS, we observed a split of the VHSs and directly imaged the spatial symmetry breaking of electronic states around the VHSs. These results suggest that electron-electron interactions play an important role in affecting the electronic properties of graphene systems with low-energy VHSs.
Mass anomalous dimension of Adjoint QCD at large N from twisted volume reduction
Pérez, Margarita García; Keegan, Liam; Okawa, Masanori
2015-01-01
In this work we consider the $SU(N)$ gauge theory with two Dirac fermions in the adjoint representation, in the limit of large $N$. In this limit the infinite-volume physics of this model can be studied by means of the corresponding twisted reduced model defined on a single site lattice. Making use of this strategy we study the reduced model for various values of $N$ up to 289. By analyzing the eigenvalue distribution of the adjoint Dirac operator we test the conformality of the theory and extract the corresponding mass anomalous dimension.
Mass anomalous dimension of adjoint QCD at large N from twisted volume reduction
Energy Technology Data Exchange (ETDEWEB)
Pérez, Margarita García [Instituto de Física Teórica UAM-CSIC, Nicolás Cabrera 13-15, Universidad Autónoma de Madrid,E-28049-Madrid (Spain); González-Arroyo, Antonio [Instituto de Física Teórica UAM-CSIC, Nicolás Cabrera 13-15, Universidad Autónoma de Madrid,E-28049-Madrid (Spain); Departamento de Física Teórica, C-XI, Universidad Autónoma de Madrid,E-28049-Madrid (Spain); Keegan, Liam [PH-TH, CERN,CH-1211 Geneva 23 (Switzerland); Okawa, Masanori [Graduate School of Science, Hiroshima University,Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Core of Research for the Energetic Universe, Hiroshima University,Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
2015-08-07
In this work we consider the SU(N) gauge theory with two Dirac fermions in the adjoint representation, in the limit of large N. In this limit the infinite-volume physics of this model can be studied by means of the corresponding twisted reduced model defined on a single site lattice. Making use of this strategy we study the reduced model for various values of N up to 289. By analyzing the eigenvalue distribution of the adjoint Dirac operator we test the conformality of the theory and extract the corresponding mass anomalous dimension.
Quark mass anomalous dimension from the twisted mass Dirac operator spectrum
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics
2013-12-15
We investigate whether it is possible to extract the quark mass anomalous dimension and its scale dependence from the spectrum of the twisted mass Dirac operator in Lattice QCD. The answer to this question appears to be positive, provided that one goes to large enough eigenvalues, sufficiently above the non-perturbative regime. The obtained results are compared to continuum perturbation theory. By analyzing possible sources of systematic effects, we find the domain of applicability of the approach, extending from an energy scale of around 1.5 to 4 GeV. The lower limit is dictated by physics (non-perturbative effects at low energies), while the upper bound is set by the ultraviolet cut-off of present-day lattice simulations. We use gauge field configuration ensembles generated by the European Twisted Mass Collaboration (ETMC) with 2 flavours of dynamical twisted mass quarks, at 4 lattice spacings in the range between around 0.04 and 0.08 fm.
Quark mass anomalous dimension from the twisted mass Dirac operator spectrum
International Nuclear Information System (INIS)
Cichy, Krzysztof; Poznan Univ.
2013-12-01
We investigate whether it is possible to extract the quark mass anomalous dimension and its scale dependence from the spectrum of the twisted mass Dirac operator in Lattice QCD. The answer to this question appears to be positive, provided that one goes to large enough eigenvalues, sufficiently above the non-perturbative regime. The obtained results are compared to continuum perturbation theory. By analyzing possible sources of systematic effects, we find the domain of applicability of the approach, extending from an energy scale of around 1.5 to 4 GeV. The lower limit is dictated by physics (non-perturbative effects at low energies), while the upper bound is set by the ultraviolet cut-off of present-day lattice simulations. We use gauge field configuration ensembles generated by the European Twisted Mass Collaboration (ETMC) with 2 flavours of dynamical twisted mass quarks, at 4 lattice spacings in the range between around 0.04 and 0.08 fm.
Flux compactifications, twisted tori and doubled geometry
International Nuclear Information System (INIS)
Reid-Edwards, R.A.
2009-01-01
In [1] an O(D,D)-covariant sigma model describing the embedding of a closed world-sheet into the 2D-dimensional twisted torus X was proposed. Such sigma models provide a universal description of string theory with target spaces related by the action of T-duality. In this article a six-dimensional toy example is studied in detail. Different polarisations of the six-dimensional target space give different three-dimensional string backgrounds including a nilmanifold with H-flux, a T-fold with R-flux and a new class of T-folds. Global issues and connections with the doubled torus formalism are discussed. Finally, the sigma model introduced in [1], describing the embedding of a world-sheet into X, is generalised to one describing a target space which is a bundle of X over a base M d , allowing for a more complete description of the associated gauged supergravity from the world-sheet perspective to be given.
Twisted conformal field theories and Morita equivalence
Energy Technology Data Exchange (ETDEWEB)
Marotta, Vincenzo [Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' and INFN, Sezione di Napoli, Compl. universitario M. Sant' Angelo, Via Cinthia, 80126 Napoli (Italy); Naddeo, Adele [CNISM, Unita di Ricerca di Salerno and Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, Via Salvador Allende, 84081 Baronissi (Italy); Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' , Compl. universitario M. Sant' Angelo, Via Cinthia, 80126 Napoli (Italy)], E-mail: adelenaddeo@yahoo.it
2009-04-01
The Morita equivalence for field theories on noncommutative two-tori is analysed in detail for rational values of the noncommutativity parameter {theta} (in appropriate units): an isomorphism is established between an Abelian noncommutative field theory (NCFT) and a non-Abelian theory of twisted fields on ordinary space. We focus on a particular conformal field theory (CFT), the one obtained by means of the m-reduction procedure [V. Marotta, J. Phys. A 26 (1993) 3481; V. Marotta, Mod. Phys. Lett. A 13 (1998) 853; V. Marotta, Nucl. Phys. B 527 (1998) 717; V. Marotta, A. Sciarrino, Mod. Phys. Lett. A 13 (1998) 2863], and show that it is the Morita equivalent of a NCFT. Finally, the whole m-reduction procedure is shown to be the image in the ordinary space of the Morita duality. An application to the physics of a quantum Hall fluid at Jain fillings {nu}=m/(2pm+1) is explicitly discussed in order to further elucidate such a correspondence and to clarify its role in the physics of strongly correlated systems. A new picture emerges, which is very different from the existing relationships between noncommutativity and many body systems [A.P. Polychronakos, arXiv: 0706.1095].
How the embryonic chick brain twists.
Chen, Zi; Guo, Qiaohang; Dai, Eric; Forsch, Nickolas; Taber, Larry A
2016-11-01
During early development, the tubular embryonic chick brain undergoes a combination of progressive ventral bending and rightward torsion, one of the earliest organ-level left-right asymmetry events in development. Existing evidence suggests that bending is caused by differential growth, but the mechanism for the predominantly rightward torsion of the embryonic brain tube remains poorly understood. Here, we show through a combination of in vitro experiments, a physical model of the embryonic morphology and mechanics analysis that the vitelline membrane (VM) exerts an external load on the brain that drives torsion. Our theoretical analysis showed that the force is of the order of 10 micronewtons. We also designed an experiment to use fluid surface tension to replace the mechanical role of the VM, and the estimated magnitude of the force owing to surface tension was shown to be consistent with the above theoretical analysis. We further discovered that the asymmetry of the looping heart determines the chirality of the twisted brain via physical mechanisms, demonstrating the mechanical transfer of left-right asymmetry between organs. Our experiments also implied that brain flexure is a necessary condition for torsion. Our work clarifies the mechanical origin of torsion and the development of left-right asymmetry in the early embryonic brain. © 2016 The Author(s).
Complex Toda theories and twisted reality conditions
International Nuclear Information System (INIS)
Evans, J.M.
1993-01-01
The Toda equations (based on a finite-dimensional or affine Lie algebra of superalgebra) are discussed as integrable non-linear differential equations for a set of complex scalar fields. We show that such complex Toda fields can either be restricted to take real values in the standard way or else they can be subjected to a 'twisted' reality condition associated to any Z 2 symmetry of the Cartan matrix or Dynkin diagram of the underlying algebra. Different reality conditions give rise to different lagrangian field theories. In the conformal case, however, these theories have the same central charge, while in the affine case they have the same mass spectrum. The construction of N=2 superconformal theories based on the superalgebras A(n, n-1) is clarified, and a new class of conformal field theories with positive kinetic energy based on the superalgebras C(n) is presented. The ideas developed are also relevant to understanding solition solutions in affine Toda theories with imaginary coupling constant. (orig.)
The Latest Twists in Chromatin Remodeling.
Blossey, Ralf; Schiessel, Helmut
2018-01-05
In its most restrictive interpretation, the notion of chromatin remodeling refers to the action of chromatin-remodeling enzymes on nucleosomes with the aim of displacing and removing them from the chromatin fiber (the effective polymer formed by a DNA molecule and proteins). This local modification of the fiber structure can have consequences for the initiation and repression of the transcription process, and when the remodeling process spreads along the fiber, it also results in long-range effects essential for fiber condensation. There are three regulatory levels of relevance that can be distinguished for this process: the intrinsic sequence preference of the histone octamer, which rules the positioning of the nucleosome along the DNA, notably in relation to the genetic information coded in DNA; the recognition or selection of nucleosomal substrates by remodeling complexes; and, finally, the motor action on the nucleosome exerted by the chromatin remodeler. Recent work has been able to provide crucial insights at each of these three levels that add new twists to this exciting and unfinished story, which we highlight in this perspective. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Mujika, Jon I; Formoso, Elena; Mercero, Jose M; Lopez, Xabier
2006-08-03
We present an ab initio study of the acid hydrolysis of a highly twisted amide and a planar amide analogue. The aim of these studies is to investigate the effect that the twist of the amide bond has on the reaction barriers and mechanism of acid hydrolysis. Concerted and stepwise mechanisms were investigated using density functional theory and polarizable continuum model calculations. Remarkable differences were observed between the mechanism of twisted and planar amide, due mainly to the preference for N-protonation of the former and O-protonation of the latter. In addition, we were also able to determine that the hydrolytic mechanism of the twisted amide will be pH dependent. Thus, there is a preference for a stepwise mechanism with formation of an intermediate in the acid hydrolysis, whereas the neutral hydrolysis undergoes a concerted-type mechanism. There is a nice agreement between the characterized intermediate and available X-ray data and a good agreement with the kinetically estimated rate acceleration of hydrolysis with respect to analogous undistorted amide compounds. This work, along with previous ab initio calculations, describes a complex and rich chemistry for the hydrolysis of highly twisted amides as a function of pH. The theoretical data provided will allow for a better understanding of the available kinetic data of the rate acceleration of amides upon twisting and the relation of the observed rate acceleration with intrinsic differential reactivity upon loss of amide bond resonance.
International Nuclear Information System (INIS)
Kingler, J.
1990-01-01
A Lund type Monte Carlo program (LUCIFER) is used to describe in perturbative QCD the pointlike component of the photon interacting on a hydrogen target. Kinematical and topological variables are developed to enhance higher twist events on the lowest order minimum twist background. The emphasis is laid on π ± , K ± higher twist mesons. (orig.)
Phosphorylation of basic helix-loop-helix transcription factor Twist in development and disease.
Xue, Gongda; Hemmings, Brian A
2012-02-01
The transcription factor Twist plays vital roles during embryonic development through regulating/controlling cell migration. However, postnatally, in normal physiological settings, Twist is either not expressed or inactivated. Increasing evidence shows a strong correlation between Twist reactivation and both cancer progression and malignancy, where the transcriptional activities of Twist support cancer cells to disseminate from primary tumours and subsequently establish a secondary tumour growth in distant organs. However, it is largely unclear how this signalling programme is reactivated or what signalling pathways regulate its activity. The present review discusses recent advances in Twist regulation and activity, with a focus on phosphorylation-dependent Twist activity, potential upstream kinases and the contribution of these factors in transducing biological signals from upstream signalling complexes. The recent advances in these areas have shed new light on how phosphorylation-dependent regulation of the Twist proteins promotes or suppresses Twist activity, leading to differential regulation of Twist transcriptional targets and thereby influencing cell fate.
Wilbur, Matthew L.; Yeager, William T., Jr.; Sekula, Martin K.
2002-01-01
The vibration reduction capabilities of a model rotor system utilizing controlled, strain-induced blade twisting are examined. The model rotor blades, which utilize piezoelectric active fiber composite actuators, were tested in the NASA Langley Transonic Dynamics Tunnel using open-loop control to determine the effect of active-twist on rotor vibratory loads. The results of this testing have been encouraging, and have demonstrated that active-twist rotor designs offer the potential for significant load reductions in future helicopter rotor systems. Active twist control was found to use less than 1% of the power necessary to operate the rotor system and had a pronounced effect on both rotating- and fixed-system loads, offering reductions in individual harmonic loads of up to 100%. A review of the vibration reduction results obtained is presented, which includes a limited set of comparisons with results generated using the second-generation version of the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD II) rotorcraft comprehensive analysis.
Finite element and analytical models for twisted and coiled actuator
Tang, Xintian; Liu, Yingxiang; Li, Kai; Chen, Weishan; Zhao, Jianguo
2018-01-01
Twisted and coiled actuator (TCA) is a class of recently discovered artificial muscle, which is usually made by twisting and coiling polymer fibers into spring-like structures. It has been widely studied since discovery due to its impressive output characteristics and bright prospects. However, its mathematical models describing the actuation in response to the temperature are still not fully developed. It is known that the large tensile stroke is resulted from the untwisting of the twisted fiber when heated. Thus, the recovered torque during untwisting is a key parameter in the mathematical model. This paper presents a simplified model for the recovered torque of TCA. Finite element method is used for evaluating the thermal stress of the twisted fiber. Based on the results of the finite element analyses, the constitutive equations of twisted fibers are simplified to develop an analytic model of the recovered torque. Finally, the model of the recovered torque is used to predict the deformation of TCA under varying temperatures and validated against experimental results. This work will enhance our understanding of the deformation mechanism of TCAs, which will pave the way for the closed-loop position control.
AKT-ions with a TWIST between EMT and MET.
Tang, Huifang; Massi, Daniela; Hemmings, Brian A; Mandalà, Mario; Hu, Zhengqiang; Wicki, Andreas; Xue, Gongda
2016-09-20
The transcription factor Twist is an important regulator of cranial suture during embryogenesis. Closure of the neural tube is achieved via Twist-triggered cellular transition from an epithelial to mesenchymal phenotype, a process known as epithelial-mesenchymal transition (EMT), characterized by a remarkable increase in cell motility. In the absence of Twist activity, EMT and associated phenotypic changes in cell morphology and motility can also be induced, albeit moderately, by other transcription factor families, including Snail and Zeb. Aberrant EMT triggered by Twist in human mammary tumour cells was first reported to drive metastasis to the lung in a metastatic breast cancer model. Subsequent analysis of many types of carcinoma demonstrated overexpression of these unique EMT transcription factors, which statistically correlated with worse outcome, indicating their potential as biomarkers in the clinic. However, the mechanisms underlying their activation remain unclear. Interestingly, increasing evidence indicates they are selectively activated by distinct intracellular kinases, thereby acting as downstream effectors facilitating transduction of cytoplasmic signals into nucleus and reprogramming EMT and mesenchymal-epithelial transition (MET) transcription to control cell plasticity. Understanding these relationships and emerging data indicating differential phosphorylation of Twist leads to complex and even paradoxical functionalities, will be vital to unlocking their potential in clinical settings.
The Twist Tensor Nuclear Norm for Video Completion.
Hu, Wenrui; Tao, Dacheng; Zhang, Wensheng; Xie, Yuan; Yang, Yehui
2017-12-01
In this paper, we propose a new low-rank tensor model based on the circulant algebra, namely, twist tensor nuclear norm (t-TNN). The twist tensor denotes a three-way tensor representation to laterally store 2-D data slices in order. On one hand, t-TNN convexly relaxes the tensor multirank of the twist tensor in the Fourier domain, which allows an efficient computation using fast Fourier transform. On the other, t-TNN is equal to the nuclear norm of block circulant matricization of the twist tensor in the original domain, which extends the traditional matrix nuclear norm in a block circulant way. We test the t-TNN model on a video completion application that aims to fill missing values and the experiment results validate its effectiveness, especially when dealing with video recorded by a nonstationary panning camera. The block circulant matricization of the twist tensor can be transformed into a circulant block representation with nuclear norm invariance. This representation, after transformation, exploits the horizontal translation relationship between the frames in a video, and endows the t-TNN model with a more powerful ability to reconstruct panning videos than the existing state-of-the-art low-rank models.
Electrical transport properties of an isolated CdS microrope composed of twisted nanowires
Yu, Gui-Feng; Yu, Miao; Pan, Wei; Han, Wen-Peng; Yan, Xu; Zhang, Jun-Cheng; Zhang, Hong-Di; Long, Yun-Ze
2015-01-01
CdS is one of the important II-VI group semiconductors. In this paper, the electrical transport behavior of an individual CdS microrope composed of twisted nanowires is studied. It is found that the current?voltage (I-V) characteristics show two distinct power law regions from 360 down to 60?K. Space-charge-limited current (SCLC) theory is used to explain these temperature- and electric-field-dependent I-V curves. The I-V data can be well fitted by this theory above 100?K, and the correspondi...
Fast Torsional Artificial Muscles from NiTi Twisted Yarns.
Mirvakili, Seyed M; Hunter, Ian W
2017-05-17
Torsional artificial muscles made of multiwalled carbon nanotube/niobium nanowire yarns have shown remarkable torsional speed and gravimetric torque. The muscle structure consists of a twisted yarn with half of its length infiltrated with a stimuli-responsive guest material such as paraffin wax. The volumetric expansion of the guest material creates the torsional actuation in the yarn. In the present work, we show that this type of actuation is not unique to wax-infiltrated carbon multiwalled nanotube (MWCNT) or niobium nanowire yarns and that twisted yarn of NiTi alloy fibers also produces fast torsional actuation. By gold-plating half the length of a NiTi twisted yarn and Joule heating it, we achieved a fully reversible torsional actuation of up to 16°/mm with peak torsional speed of 10 500 rpm and gravimetric torque of 8 N·m/kg. These results favorably compare to those of MWCNTs and niobium nanowire yarns.
From starproducts to Drinfeld-twists. Present and future applications
International Nuclear Information System (INIS)
Koch, Florian
2008-01-01
Physics comes up with models that invoke noncommutative structures in configuration space. Such structures are dual to the deformed coalgebra sector of a represented symmetry algebra. In the mean time such deformations are performed in terms of the symmetry algebra itself via twists or quasitriangular structures. One might thus find oneself in the bad situation that the symmetry algebra is not large enough to provide the required twist that dually matches the noncommutative structure found. It thus has to remain in the unpleasant state of being without any notion of symmetry. We show how starproducts can be pushed to twists by introducing a larger algebra that accommodates any finite dimensional representation of a Lie-algebra. This new algebra is similar to a Heisenberg-algebra but in contrast to the latter can be enhanced to a Hopf-algebra. Some Examples are given. (author)
Twisted vertex algebras, bicharacter construction and boson-fermion correspondences
International Nuclear Information System (INIS)
Anguelova, Iana I.
2013-01-01
The boson-fermion correspondences are an important phenomena on the intersection of several areas in mathematical physics: representation theory, vertex algebras and conformal field theory, integrable systems, number theory, cohomology. Two such correspondences are well known: the types A and B (and their super extensions). As a main result of this paper we present a new boson-fermion correspondence of type D-A. Further, we define a new concept of twisted vertex algebra of order N, which generalizes super vertex algebra. We develop the bicharacter construction which we use for constructing classes of examples of twisted vertex algebras, as well as for deriving formulas for the operator product expansions, analytic continuations, and normal ordered products. By using the underlying Hopf algebra structure we prove general bicharacter formulas for the vacuum expectation values for two important groups of examples. We show that the correspondences of types B, C, and D-A are isomorphisms of twisted vertex algebras
Iterative methods for overlap and twisted mass fermions
International Nuclear Information System (INIS)
Chiarappa, T.; Jansen, K.; Shindler, A.; Wetzorke, I.; Scorzato, L.; Urbach, C.; Wenger, U.
2006-09-01
We present a comparison of a number of iterative solvers of linear systems of equations for obtaining the fermion propagator in lattice QCD. In particular, we consider chirally invariant overlap and chirally improved Wilson (maximally) twisted mass fermions. The comparison of both formulations of lattice QCD is performed at four fixed values of the pion mass between 230 MeV and 720 MeV. For overlap fermions we address adaptive precision and low mode preconditioning while for twisted mass fermions we discuss even/odd preconditioning. Taking the best available algorithms in each case we find that calculations with the overlap operator are by a factor of 30-120 more expensive than with the twisted mass operator. (orig.)
Iterative methods for overlap and twisted mass fermions
Energy Technology Data Exchange (ETDEWEB)
Chiarappa, T. [Univ. di Milano Bicocca (Italy); Jansen, K.; Shindler, A.; Wetzorke, I. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Nagai, K.I. [Wuppertal Univ. (Gesamthochschule) (Germany). Fachbereich Physik; Papinutto, M. [INFN Sezione di Roma Tre, Rome (Italy); Scorzato, L. [European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT), Villazzano (Italy); Urbach, C. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Wenger, U. [ETH Zuerich (Switzerland). Inst. fuer Theoretische Physik
2006-09-15
We present a comparison of a number of iterative solvers of linear systems of equations for obtaining the fermion propagator in lattice QCD. In particular, we consider chirally invariant overlap and chirally improved Wilson (maximally) twisted mass fermions. The comparison of both formulations of lattice QCD is performed at four fixed values of the pion mass between 230 MeV and 720 MeV. For overlap fermions we address adaptive precision and low mode preconditioning while for twisted mass fermions we discuss even/odd preconditioning. Taking the best available algorithms in each case we find that calculations with the overlap operator are by a factor of 30-120 more expensive than with the twisted mass operator. (orig.)
Template preparation of twisted nanoparticles of mesoporous silica
Institute of Scientific and Technical Information of China (English)
Kui Niu; Zhongbin Ni; Chengwu Fu; Tatsuo Kaneko; Mingqing Chen
2011-01-01
Optical isomers of N-lauroyl-L-(or-D-) alanine sodium salt {C12-L-(or-D-)AlaS} surfactants were used for the preparation of mesoporous silica nanoparticles with a twisted hexagonal rod-like morphology. Thermogravimetric analysis (TGA) was used to determine the temperature for template removal. Circular dichroism (CD) spectra of the surfactant solution with various compositions illustrated the formation and supramolecular assembly of protein-like molecular architecture leading to formation of twisted nanoparticles. Scanning electron microscopy (SEM),high-resolution transmission electron microscopy (HRTEM)and X-ray powder diffraction (XRD) patterns of these as-synthesized mesoporous silica confirmed that the twisted morphology of these nanoparticles was closely related to the supramolecular-assembled complex of amino acid surfactants.
Twisted spin Sutherland models from quantum Hamiltonian reduction
International Nuclear Information System (INIS)
Feher, L; Pusztai, B G
2008-01-01
Recent general results on Hamiltonian reductions under polar group actions are applied to study some reductions of the free particle governed by the Laplace-Beltrami operator of a compact, connected, simple Lie group. The reduced systems associated with arbitrary finite-dimensional irreducible representations of the group by using the symmetry induced by twisted conjugations are described in detail. These systems generically yield integrable Sutherland-type many-body models with spin, which are called twisted spin Sutherland models if the underlying twisted conjugations are built on non-trivial Dynkin diagram automorphisms. The spectra of these models can be calculated, in principle, by solving certain Clebsch-Gordan problems, and the result is presented for the models associated with the symmetric tensorial powers of the defining representation of SU(N)
Meng, Guangrong; Shi, Shicheng; Lalancette, Roger; Szostak, Roman; Szostak, Michal
2018-01-17
Since the seminal studies by Pauling in 1930s, planarity has become the defining characteristic of the amide bond. Planarity of amides has central implications for the reactivity and chemical properties of amides of relevance to a range of chemical disciplines. While the vast majority of amides are planar, nonplanarity has a profound effect on the properties of the amide bond, with the most common method to restrict the amide bond relying on the incorporation of the amide function into a rigid cyclic ring system. In a major departure from this concept, here, we report the first class of acyclic twisted amides that can be prepared, reversibly, from common primary amides in a single, operationally trivial step. Di-tert-butoxycarbonylation of the amide nitrogen atom yields twisted amides in which the amide bond exhibits nearly perpendicular twist. Full structural characterization of a range of electronically diverse compounds from this new class of twisted amides is reported. Through reactivity studies we demonstrate unusual properties of the amide bond, wherein selective cleavage of the amide bond can be achieved by a judicious choice of the reaction conditions. Through computational studies we evaluate structural and energetic details pertaining to the amide bond deformation. The ability to selectively twist common primary amides, in a reversible manner, has important implications for the design and application of the amide bond nonplanarity in structural chemistry, biochemistry and organic synthesis.
Light baryon masses with dynamical twisted mass fermions
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Baron, R. [CEA-Saclay, IRFU/Service de Physique Nucleaire, Gif-sur-Yvette (France); Blossier, B. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (DE). John von Neumann-Inst. fuer Computing NIC] (and others)
2008-03-15
We present results on the mass of the nucleon and the {delta} using two dynamical degenerate twisted mass quarks. The evaluation is performed at four quark masses corresponding to a pion mass in the range of about 300-600 MeV on lattices of 2.1-2.7 fm. We check for cut-off effects by evaluating these baryon masses on lattices of spatial size 2.1 fm at {beta}=3.9 and {beta}=4.05 and on a lattice of 2.4 fm at {beta}=3.8. The values we find are compatible within our statistical errors. Lattice results are extrapolated to the physical limit using continuum chiral perturbation theory. Performing a combined fit to our lattice data at {beta}=3.9 and {beta}=4.05 we find a nucleon mass of 964{+-}28(stat.){+-}8(syst.) MeV where we used the lattice spacings determined from the pion decay constant to convert to physical units. The systematic error due to the chiral extrapolation is estimated by comparing results obtained at O(p{sup 3}) and O(p{sup 4}) heavy baryon chiral perturbation theory. The nucleon mass at the physical point provides an independent determination of the lattice spacing. Using heavy baryon chiral perturbation theory at O(p{sup 3}) we find a{sub {beta}}{sub =3.9}=0.0890{+-}0.0039(stat.){+-}0.0014(syst.) fm, and a{sub {beta}}{sub =4.05}=0.0691{+-}0.0034(stat.){+-}0.0010(syst.) fm, in good agreement with the values determined from the pion decay constant. Using results from our two smaller lattices spacings at constant r0m we estimate the continuum limit and check consistency with results from the coarser lattice. Results at the continuum limit are chirally extrapolated to the physical point. Isospin violating lattice artifacts in the {delta}-system are found to be compatible with zero for the values of the lattice spacings used in this work. Performing a combined fit to our lattice data at {beta}=3.9 and {beta}=4.05 we find for the masses of the {delta}{sup ++,-} and {delta}{sup +,0} 1316{+-}60(stat.) MeV and 1330{+-}74(stat.) MeV respectively. We confirm
Light baryon masses with dynamical twisted mass fermions
International Nuclear Information System (INIS)
Alexandrou, C.; Blossier, B.
2008-03-01
We present results on the mass of the nucleon and the Δ using two dynamical degenerate twisted mass quarks. The evaluation is performed at four quark masses corresponding to a pion mass in the range of about 300-600 MeV on lattices of 2.1-2.7 fm. We check for cut-off effects by evaluating these baryon masses on lattices of spatial size 2.1 fm at β=3.9 and β=4.05 and on a lattice of 2.4 fm at β=3.8. The values we find are compatible within our statistical errors. Lattice results are extrapolated to the physical limit using continuum chiral perturbation theory. Performing a combined fit to our lattice data at β=3.9 and β=4.05 we find a nucleon mass of 964±28(stat.)±8(syst.) MeV where we used the lattice spacings determined from the pion decay constant to convert to physical units. The systematic error due to the chiral extrapolation is estimated by comparing results obtained at O(p 3 ) and O(p 4 ) heavy baryon chiral perturbation theory. The nucleon mass at the physical point provides an independent determination of the lattice spacing. Using heavy baryon chiral perturbation theory at O(p 3 ) we find a β=3.9 =0.0890±0.0039(stat.)±0.0014(syst.) fm, and a β=4.05 =0.0691±0.0034(stat.)±0.0010(syst.) fm, in good agreement with the values determined from the pion decay constant. Using results from our two smaller lattices spacings at constant r0m we estimate the continuum limit and check consistency with results from the coarser lattice. Results at the continuum limit are chirally extrapolated to the physical point. Isospin violating lattice artifacts in the Δ-system are found to be compatible with zero for the values of the lattice spacings used in this work. Performing a combined fit to our lattice data at β=3.9 and β=4.05 we find for the masses of the Δ ++,- and Δ +,0 1316±60(stat.) MeV and 1330±74(stat.) MeV respectively. We confirm that in the continuum limit they are also degenerate. (orig.)
Light baryon masses with dynamical twisted mass fermions
International Nuclear Information System (INIS)
Alexandrou, C.; Korzec, T.; Koutsou, G.; Baron, R.; Guichon, P.; Blossier, B.; Herdoiza, G.; Jansen, K.; Brinet, M.; Carbonell, J.; Drach, V.; Dimopoulos, P.; Frezzotti, R.; Farchioni, F.; Liu, Z.; Pene, O.; Michael, C.; Shindler, A.; Urbach, C.; Wenger, U.
2008-01-01
We present results on the mass of the nucleon and the Δ using two dynamical degenerate twisted mass quarks and the tree-level Symanzik improved gauge action. The evaluation is performed at four quark masses corresponding to a pion mass in the range of about 300-600 MeV on lattices of 2.1-2.7 fm at three lattice spacings less than 0.1 fm. We check for cutoff effects by evaluating these baryon masses on lattices of spatial size 2.1 fm at β=3.9 and β=4.05 and on a lattice of 2.4 fm at β=3.8. The values we find are compatible within our statistical errors. Lattice results are extrapolated to the physical limit using continuum chiral perturbation theory. Performing a combined fit to our lattice data at β=3.9 and β=4.05 we find a nucleon mass of 963±12(stat)±8(syst) MeV where we used the lattice spacings determined from the pion decay constant to convert to physical units. The systematic error due to the chiral extrapolation is estimated by comparing results obtained at O(p 3 ) and O(p 4 ) heavy baryon chiral perturbation theory. The nucleon mass at the physical point provides an independent determination of the lattice spacing. Using heavy baryon chiral perturbation theory at O(p 3 ) we find a β=3.9 =0.0889±0.0012(stat)±0.0014(syst) fm, and a β=4.05 =0.0691±0.0010(stat)±0.0010(syst) fm, in good agreement with the values determined from the pion decay constant. Using results from our two smaller lattices spacings at constant r 0 m π we estimate the continuum limit and check consistency with results from the coarser lattice. Results at the continuum limit are chirally extrapolated to the physical point. Isospin violating lattice artifacts in the Δ-system are found to be compatible with zero for the values of the lattice spacings used in this work. Performing a combined fit to our lattice data at β=3.9 and β=4.05 we find for the masses of the Δ ++,- and Δ +,0 1315±24(stat) MeV and 1329±30(stat) MeV, respectively. We confirm that in the continuum limit
Modeling higher twist contributions to deep inelastic scattering with diquarks
International Nuclear Information System (INIS)
Anselmino, M.
1994-01-01
The most recent detailed data on the unpolarized nucleon structure functions allow a precise determination of higher twist contributions. Quark-quark correlations induced by color forces are expected to be a natural explanation for such effects; indeed, a quark-diquark picture of the nucleon, previously introduced in the description of several exclusive processes at intermediate Q 2 values, is found to model the proton higher twist data with great accuracy. The resulting parameters are consistent with the diquark properties suggested by other experimental and theoretical analyses. (author)
Modelling higher twist contributions to deep inelastic scattering with diquarks
International Nuclear Information System (INIS)
Anselmino, M.; Caruso, F.; Penna Firme, A.; Soares, J.; Mello Neto, J.R.T. de
1994-08-01
The most recent detailed data on the unpolarized nucleon structure functions allow a precise determination of higher twist contributions. Quark-quark correlations induced by colour forces are expected to be a natural explanation for such effects: indeed, a quark-diquark picture of the nucleon, previously introduced in the description of several exclusive processes at intermediate Q 2 values, is found to model the proton higher twist data with great accuracy. The resulting parameters are consistent with the diquark properties suggested by other experimental and theoretical analyses. (author). 15 refs, 5 figs
Anomalous phase shift in a twisted quantum loop
International Nuclear Information System (INIS)
Taira, Hisao; Shima, Hiroyuki
2010-01-01
The coherent motion of electrons in a twisted quantum ring is considered to explore the effect of torsion inherent to the ring. Internal torsion of the ring composed of helical atomic configuration yields a non-trivial quantum phase shift in the electrons' eigenstates. This torsion-induced phase shift causes novel kinds of persistent current flow and an Aharonov-Bohm-like conductance oscillation. The two phenomena can occur even when no magnetic flux penetrates inside the twisted ring, thus being in complete contrast with the counterparts observed in untwisted rings.
Note on twisted elliptic genus of K3 surface
Energy Technology Data Exchange (ETDEWEB)
Eguchi, Tohru, E-mail: eguchi@yukawa.kyoto-u.ac.j [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Hikami, Kazuhiro, E-mail: KHikami@gmail.co [Department of Mathematics, Naruto University of Education, Tokushima 772-8502 (Japan)
2011-01-03
We discuss the possibility of Mathieu group M{sub 24} acting as symmetry group on the K3 elliptic genus as proposed recently by Ooguri, Tachikawa and one of the present authors. One way of testing this proposal is to derive the twisted elliptic genera for all conjugacy classes of M{sub 24} so that we can determine the unique decomposition of expansion coefficients of K3 elliptic genus into irreducible representations of M{sub 24}. In this Letter we obtain all the hitherto unknown twisted elliptic genera and find a strong evidence of Mathieu moonshine.
Note on twisted elliptic genus of K3 surface
International Nuclear Information System (INIS)
Eguchi, Tohru; Hikami, Kazuhiro
2011-01-01
We discuss the possibility of Mathieu group M 24 acting as symmetry group on the K3 elliptic genus as proposed recently by Ooguri, Tachikawa and one of the present authors. One way of testing this proposal is to derive the twisted elliptic genera for all conjugacy classes of M 24 so that we can determine the unique decomposition of expansion coefficients of K3 elliptic genus into irreducible representations of M 24 . In this Letter we obtain all the hitherto unknown twisted elliptic genera and find a strong evidence of Mathieu moonshine.
Gerbes over posets and twisted C*-dynamical systems
Vasselli, Ezio
2017-01-01
A base $\\Delta$ generating the topology of a space $M$ becomes a partially ordered set (poset), when ordered under inclusion of open subsets. Given a precosheaf over $\\Delta$ of fixed-point spaces (typically C*-algebras) under the action of a group $G$, in general one cannot find a precosheaf of $G$-spaces having it as fixed-point precosheaf. Rather one gets a gerbe over $\\Delta$, that is, a "twisted precosheaf" whose twisting is encoded by a cocycle with coefficients in a suitable 2-group. W...
Directory of Open Access Journals (Sweden)
Katharina Seitz
Full Text Available β-Catenin independent, non-canonical Wnt signaling pathways play a major role in the regulation of morphogenetic movements in vertebrates. The term non-canonical Wnt signaling comprises multiple, intracellularly divergent, Wnt-activated and β-Catenin independent signaling cascades including the Wnt/Planar Cell Polarity and the Wnt/Ca(2+ cascades. Wnt/Planar Cell Polarity and Wnt/Ca(2+ pathways share common effector proteins, including the Wnt ligand, Frizzled receptors and Dishevelled, with each other and with additional branches of Wnt signaling. Along with the aforementioned proteins, β-Arrestin has been identified as an essential effector protein in the Wnt/β-Catenin and the Wnt/Planar Cell Polarity pathway. Our results demonstrate that β-Arrestin is required in the Wnt/Ca(2+ signaling cascade upstream of Protein Kinase C (PKC and Ca(2+/Calmodulin-dependent Protein Kinase II (CamKII. We have further characterized the role of β-Arrestin in this branch of non-canonical Wnt signaling by knock-down and rescue experiments in Xenopus embryo explants and analyzed protein-protein interactions in 293T cells. Functional interaction of β-Arrestin, the β subunit of trimeric G-proteins and Dishevelled is required to induce PKC activation and membrane translocation. In Xenopus gastrulation, β-Arrestin function in Wnt/Ca(2+ signaling is essential for convergent extension movements. We further show that β-Arrestin physically interacts with the β subunit of trimeric G-proteins and Dishevelled, and that the interaction between β-Arrestin and Dishevelled is promoted by the beta/gamma subunits of trimeric G-proteins, indicating the formation of a multiprotein signaling complex.
Geometry of the toroidal N-helix: optimal-packing and zero-twist
DEFF Research Database (Denmark)
Olsen, Kasper; Bohr, Jakob
2012-01-01
Two important geometrical properties of N-helix structures are influenced by bending. One is maximizing the volume fraction, which is called optimal-packing, and the other is having a vanishing strain-twist coupling, which is called zero-twist. Zero-twist helices rotate neither in one nor...... helix. General N-helices are discussed, as well as zero-twist helices for N > 1. The derived geometrical restrictions are gradually modified by changing the aspect ratio of the torus....
On the space of connections having non-trivial twisted harmonic spinors
International Nuclear Information System (INIS)
Bei, Francesco; Waterstraat, Nils
2015-01-01
We consider Dirac operators on odd-dimensional compact spin manifolds which are twisted by a product bundle. We show that the space of connections on the twisting bundle which yields an invertible operator has infinitely many connected components if the untwisted Dirac operator is invertible and the dimension of the twisting bundle is sufficiently large
Twisting failure of centrally loaded open-section columns in the elastic range
Kappus, Robert
1938-01-01
In the following report a complete theory of twisting failure by the energy method is developed, based on substantially the same assumptions as those employed by Wagner and Bleich. Problems treated in detail are: the stress and strain condition under St. Venant twist and in twist with axial constraint; the concept of shear center and the energy method for problems of elastic stability.
On the space of connections having non-trivial twisted harmonic spinors
Energy Technology Data Exchange (ETDEWEB)
Bei, Francesco, E-mail: bei@math.hu-berlin.de [Institut für Mathematik, Humboldt Universität zu Berlin, Unter den Linden 6, 10099 Berlin (Germany); Waterstraat, Nils, E-mail: n.waterstraat@kent.ac.uk [School of Mathematics, Statistics & Actuarial Science, University of Kent, Canterbury, Kent CT2 7NF (United Kingdom)
2015-09-15
We consider Dirac operators on odd-dimensional compact spin manifolds which are twisted by a product bundle. We show that the space of connections on the twisting bundle which yields an invertible operator has infinitely many connected components if the untwisted Dirac operator is invertible and the dimension of the twisting bundle is sufficiently large.
Mechanisms of Twist 1-Induced Invasion in Breast Cancer Metastasis
2011-01-01
affect breast cancer metastasis with a subcutaneous mouse tumor implantation model of breast cancer metastasis. HMLE -Twist1 cells expressing shRNAs...13 4 Introduction Distant metastases are responsible for the vast majority of breast cancer deaths. This process...to migrate and invade is therefore essential to the metastatic process. The initial steps of breast cancer metastasis, local invasion and
Determinant of twisted chiral Dirac operator on the lattice
International Nuclear Information System (INIS)
Fosco, C.D.; Randjbar Daemi, S.
1995-04-01
Using the overlap formulation, we calculate the fermionic determinant on the lattice for chiral fermions with twisted boundary conditions in two dimensions. When the lattice spacing tends to zero we recover the results on the usual string-theory continuum calculations. (author). 13 refs
Stability of coupled tearing and twisting modes in tokamaks
International Nuclear Information System (INIS)
Fitzpatrick, R.
1994-03-01
A dispersion relation is derived for resistive modes of arbitrary parity in a tokamak plasma. At low mode amplitude, tearing and twisting modes which have nonideal MHD behavior at only one rational surface at a time in the plasma are decoupled via sheared rotation and diamagnetic flows. At higher amplitude, more unstable open-quote compound close-quote modes develop which have nonideal behavior simultaneously at many surfaces. Such modes possess tearing parity layers at some of the nonideal surfaces, and twisting parity layers at others, but mixed parity layers are generally disallowed. At low mode number, open-quote compound close-quote modes are likely to have tearing parity layers at all of the nonideal surfaces in a very low-β plasma, but twisting parity layers become more probable as the plasma β is increased. At high mode number, unstable twisting modes which exceed a critical amplitude drive conventional magnetic island chains on alternate rational surfaces, to form an interlocking structure in which the O-points and X-points of neighboring chains line up
Spectral estimates for Dirichlet Laplacians on perturbed twisted tubes
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Barseghyan, Diana
2014-01-01
Roč. 8, č. 1 (2014), s. 167-183 ISSN 1846-3886 R&D Projects: GA ČR GAP203/11/0701 Institutional support: RVO:61389005 Keywords : Drichlet Laplacian * twisted tube * discrete spectrum * eigenvalue estimates Subject RIV: BE - Theoretical Physics Impact factor: 0.583, year: 2014
Casimir energy for twisted piecewise uniform bosonic strings
International Nuclear Information System (INIS)
Lu, J.; Huang, B.; Shanghai, Teachers Univ.
1998-01-01
The Casimir energy for the transverse oscillations of piecewise uniform bosonic strings with either untwisted or twisted continuous conditions is discussed. After calculating the analytic values of zeros of the dispersion function under certain conditions, is obtained the Casimir energy for both open and closed bosonic strings composed of two or three segments
Twisted equivariant K-theory, groupoids and proper actions
Cantarero, Jose
2009-01-01
In this paper we define twisted equivariant K-theory for actions of Lie groupoids. For a Bredon-compatible Lie groupoid, this defines a periodic cohomology theory on the category of finite CW-complexes with equivariant stable projective bundles. A classification of these bundles is shown. We also obtain a completion theorem and apply these results to proper actions of groups.
Fermionic construction of vertex operators for twisted affine algebras
International Nuclear Information System (INIS)
Frappat, L.; Sorba, P.; Sciarrino, A.
1988-03-01
We construct vertex operator representations of the twisted affine algebras in terms of fermionic (or parafermionic in some cases) elementary fields. The folding method applied to the extended Dynkin diagrams of the affine algebras allows us to determine explicitly these fermionic fields as vertex operators
Heat bath method for the twisted Eguchi-Kawai model
International Nuclear Information System (INIS)
Fabricius, K.; Haan, O.
1984-01-01
We reformulate the twisted Eguchi-Kawaii model in a way that allows us to use the heat bath method for the updating procedure of the link matrices. This new formulation is more efficient by a factor of 2.5 in computer time and of 2.3 in memory need. (orig.)
Heat bath method for the twisted Eguchi-Kawai model
Energy Technology Data Exchange (ETDEWEB)
Fabricius, K.; Haan, O.
1984-08-16
We reformulate the twisted Eguchi-Kawaii model in a way that allows us to use the heat bath method for the updating procedure of the link matrices. This new formulation is more efficient by a factor of 2.5 in computer time and of 2.3 in memory need.
Twisted mass lattice QCD with non-degenerate quark masses
International Nuclear Information System (INIS)
Muenster, Gernot; Sudmann, Tobias
2006-01-01
Quantum Chromodynamics on a lattice with Wilson fermions and a chirally twisted mass term is considered in the framework of chiral perturbation theory. For two and three numbers of quark flavours, respectively, with non-degenerate quark masses the pseudoscalar meson masses and decay constants are calculated in next-to-leading order including lattice effects quadratic in the lattice spacing a
Twist-2 Light-Cone Pion Wave Function
Belyaev, V. M.; Johnson, Mikkel B.
1997-01-01
We present an analysis of the existing constraints for the twist-2 light-cone pion wave function. We find that existing information on the pion wave function does not exclude the possibility that the pion wave function attains its asymptotic form. New bounds on the parameters of the pion wave function are presented.
Controlling coupled bending-twisting vibrations of anisotropic composite wing
Ryabov, Victor; Yartsev, Boris
2018-05-01
The paper discusses the possibility to control coupled bending-twisting vibrations of anisotropic composite wing by means of the monoclinic structures in the reinforcement of the plating. Decomposing the potential straining energy and kinetic energy of natural vibration modes into interacting and non-interacting parts, it became possible to introduce the two coefficients that integrally consider the effect of geometry and reinforcement structure upon the dynamic response parameters of the wing. The first of these coefficients describes the elastic coupling of the natural vibration modes, the second coefficient describes the inertial one. The paper describes the numerical studies showing how the orientation of considerably anisotropic CRP layers in the plating affects natural frequencies, loss factors, coefficients of elastic and inertial coupling for several lower tones of natural bending-twisting vibrations of the wing. Besides, for each vibration mode, partial values of the above mentioned dynamic response parameters were determined by means of the relationships for orthotropic structures where instead of "free" shearing modulus in the reinforcement plant, "pure" shearing modulus is used. Joint analysis of the obtained results has shown that each pair of bending-twisting vibration modes has its orientation angle ranges of the reinforcing layers where the inertial coupling caused by asymmetry of the cross-section profile with respect to the main axes of inertia decreases, down to the complete extinction, due to the generation of the elastic coupling in the plating material. These ranges are characterized by the two main features: 1) the difference in the natural frequencies of the investigated pair of bending-twisting vibration modes is the minimum and 2) natural frequencies of bending-twisting vibrations belong to a stretch restricted by corresponding partial natural frequencies of the investigated pair of vibration modes. This result is of practical importance
Intermittent energy bursts and recurrent topological change of a twisting magnetic flux tube
International Nuclear Information System (INIS)
Amo, Hiroyoshi; Sato, Tetsuya; Kageyama, Akira.
1994-09-01
When continuously twisted, a magnetic flux tube suffers a large kink distortion in the middle part of the tube, like a knot-of-tension instability of a bundle of twisted rubber strings, and reconnection is triggered starting with the twisted field lines and quickly proceeding to the untwisted field lines at the twist-untwist boundary, whereby a giant burst-like energy release takes place. Subsequently, bursts occur intermittently and reconnection advances deeper into the untwisted region. Then, a companion pair of the linked twist-untwist flux tubes reconnect with each other to return to the original axisymmetric tube. The process is thus repeatable. (author)
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.
Unique CCT repeats mediate transcription of the TWIST1 gene in mesenchymal cell lines
International Nuclear Information System (INIS)
Ohkuma, Mizue; Funato, Noriko; Higashihori, Norihisa; Murakami, Masanori; Ohyama, Kimie; Nakamura, Masataka
2007-01-01
TWIST1, a basic helix-loop-helix transcription factor, plays critical roles in embryo development, cancer metastasis and mesenchymal progenitor differentiation. Little is known about transcriptional regulation of TWIST1 expression. Here we identified DNA sequences responsible for TWIST1 expression in mesenchymal lineage cell lines. Reporter assays with TWIST1 promoter mutants defined the -102 to -74 sequences that are essential for TWIST1 expression in human and mouse mesenchymal cell lines. Tandem repeats of CCT, but not putative CREB and NF-κB sites in the sequences substantially supported activity of the TWIST1 promoter. Electrophoretic mobility shift assay demonstrated that the DNA sequences with the CCT repeats formed complexes with nuclear factors, containing, at least, Sp1 and Sp3. These results suggest critical implication of the CCT repeats in association with Sp1 and Sp3 factors in sustaining expression of the TWIST1 gene in mesenchymal cells
Quasilocal conservation laws in XXZ spin-1/2 chains: Open, periodic and twisted boundary conditions
Directory of Open Access Journals (Sweden)
Tomaž Prosen
2014-09-01
Full Text Available A continuous family of quasilocal exact conservation laws is constructed in the anisotropic Heisenberg (XXZ spin-1/2 chain for periodic (or twisted boundary conditions and for a set of commensurate anisotropies densely covering the entire easy plane interaction regime. All local conserved operators follow from the standard (Hermitian transfer operator in fundamental representation (with auxiliary spin s=1/2, and are all even with respect to a spin flip operation. However, the quasilocal family is generated by differentiation of a non-Hermitian highest weight transfer operator with respect to a complex auxiliary spin representation parameter s and includes also operators of odd parity. For a finite chain with open boundaries the time derivatives of quasilocal operators are not strictly vanishing but result in operators localized near the boundaries of the chain. We show that a simple modification of the non-Hermitian transfer operator results in exactly conserved, but still quasilocal operators for periodic or generally twisted boundary conditions. As an application, we demonstrate that implementing the new exactly conserved operator family for estimating the high-temperature spin Drude weight results, in the thermodynamic limit, in exactly the same lower bound as for almost conserved family and open boundaries. Under the assumption that the bound is saturating (suggested by agreement with previous thermodynamic Bethe ansatz calculations we propose a simple explicit construction of infinite time averages of local operators such as the spin current.
Evolution equation for the higher-twist B-meson distribution amplitude
International Nuclear Information System (INIS)
Braun, V.M.; Offen, N.; Manashov, A.N.; Regensburg Univ.; Sankt-Petersburg State Univ.
2015-07-01
We find that the evolution equation for the three-particle quark-gluon B-meson light-cone distribution amplitude (DA) of subleading twist is completely integrable in the large N c limit and can be solved exactly. The lowest anomalous dimension is separated from the remaining, continuous, spectrum by a finite gap. The corresponding eigenfunction coincides with the contribution of quark-gluon states to the two-particle DA φ - (ω) so that the evolution equation for the latter is the same as for the leading-twist DA φ + (ω) up to a constant shift in the anomalous dimension. Thus, ''genuine'' three-particle states that belong to the continuous spectrum effectively decouple from φ - (ω) to the leading-order accuracy. In turn, the scale dependence of the full three-particle DA turns out to be nontrivial so that the contribution with the lowest anomalous dimension does not become leading at any scale. The results are illustrated on a simple model that can be used in studies of 1/m b corrections to heavy-meson decays in the framework of QCD factorization or light-cone sum rules.
Flavor-singlet meson decay constants from Nf=2 +1 +1 twisted mass lattice QCD
Ottnad, Konstantin; Urbach, Carsten; ETM Collaboration
2018-03-01
We present an improved analysis of our lattice data for the η - η' system, including a correction of the relevant correlation functions for residual topological finite size effects and employing consistent chiral and continuum fits. From this analysis we update our physical results for the masses Mη=557 (11 )stat(03 )χ PT MeV and Mη'=911 (64 )stat(03 )χ PT MeV , as well as the mixing angle in the quark flavor basis ϕ =38.8 (2.2 )stat(2.4 )χPT ∘ in excellent agreement with other results from phenomenology. Similarly, we include an analysis for the decay constant parameters, leading to fl=125 (5 )stat(6 )χ PT MeV and fs=178 (4 )stat(1 )χ PT MeV . The second error reflects the uncertainty related to the chiral extrapolation. The data used for this study has been generated on gauge ensembles provided by the European Twisted Mass Collaboration with Nf=2 +1 +1 dynamical flavors of Wilson twisted mass fermions. These ensembles cover a range of pion masses from 220 MeV to 500 MeV and three values of the lattice spacing. Combining our data with a prediction from chiral perturbation theory, we give an estimate for the physical η , η'→γ γ decay widths and the singly-virtual η , η'→γ γ* transition form factors in the limit of large momentum transfer.
Controlling fracture cascades through twisting and quenching
Heisser, Ronald H.; Patil, Vishal P.; Stoop, Norbert; Dunkel, Jörn
2018-01-01
Fracture limits the structural stability of macroscopic and microscopic materials, from beams and bones to microtubules and nanotubes. Despite recent progress, fracture control continues to present profound practical and theoretical challenges. A famous longstanding problem posed by Feynman asks why brittle elastic rods appear almost always to fragment into at least three pieces when placed under large bending stresses. Feynman's observation raises fundamental questions about the existence of...
Overlap valence quarks on a twisted mass sea. A case study for mixed action lattice QCD
International Nuclear Information System (INIS)
Cichy, Krzysztof; Herdoiza, Gregorio; UAM/CSIC Univ. Autonoma de Madrid
2012-11-01
We discuss a Lattice QCD mixed action investigation employing Wilson maximally twisted mass sea and overlap valence fermions. Using four values of the lattice spacing, we demonstrate that the overlap Dirac operator assumes a point-like locality in the continuum limit. We also show that by adopting suitable matching conditions for the sea and valence theories a consistent continuum limit for the pion decay constant and light baryon masses can be obtained. Finally, we confront results for sea-valence mixed meson masses and the valence scalar correlator with corresponding expressions of chiral perturbation theory. This allows us to extract low energy constants of mixed action chiral perturbation which characterize the strength of unitarity violations in our mixed action setup.
Overlap valence quarks on a twisted mass sea. A case study for mixed action lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Drach, Vincent; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Herdoiza, Gregorio [UAM/CSIC Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; UAM/CSIC Univ. Autonoma de Madrid (Spain). Inst. de Fisica Teorica; Collaboration: European Twisted Mass Collaboration
2012-11-15
We discuss a Lattice QCD mixed action investigation employing Wilson maximally twisted mass sea and overlap valence fermions. Using four values of the lattice spacing, we demonstrate that the overlap Dirac operator assumes a point-like locality in the continuum limit. We also show that by adopting suitable matching conditions for the sea and valence theories a consistent continuum limit for the pion decay constant and light baryon masses can be obtained. Finally, we confront results for sea-valence mixed meson masses and the valence scalar correlator with corresponding expressions of chiral perturbation theory. This allows us to extract low energy constants of mixed action chiral perturbation which characterize the strength of unitarity violations in our mixed action setup.
Alexandrou, Constantia; Athenodorou, Andreas; Cichy, Krzysztof; Constantinou, Martha; Horkel, Derek P.; Jansen, Karl; Koutsou, Giannis; Larkin, Conor
2018-04-01
We compare lattice QCD determinations of topological susceptibility using a gluonic definition from the gradient flow and a fermionic definition from the spectral-projector method. We use ensembles with dynamical light, strange and charm flavors of maximally twisted mass fermions. For both definitions of the susceptibility we employ ensembles at three values of the lattice spacing and several quark masses at each spacing. The data are fitted to chiral perturbation theory predictions with a discretization term to determine the continuum chiral condensate in the massless limit and estimate the overall discretization errors. We find that both approaches lead to compatible results in the continuum limit, but the gluonic ones are much more affected by cutoff effects. This finally yields a much smaller total error in the spectral-projector results. We show that there exists, in principle, a value of the spectral cutoff which would completely eliminate discretization effects in the topological susceptibility.
A torsional artificial muscle from twisted nitinol microwire
Mirvakili, Seyed M.; Hunter, Ian W.
2017-04-01
Nitinol microwires of 25 μm in diameter can have tensile actuation of up to 4.5% in less than 100 ms. A work density of up to 480 MPa can be achieved from these microwires. In the present work, we are showing that by twisting the microwires in form of closed-loop two-ply yarn we can create a torsional actuator. We achieved a revisable torsional stroke of 46°/mm with peak rotational speed of up to 10,000 rpm. We measured a gravimetric torque of up to 28.5 N•m/kg which is higher than the 3 - 6 N•m/kg for direct-drive commercial electric motors. These remarkable performance results are comparable to those of guest-infiltrated carbon nanotube twisted yarns.
Twisted-Light-Ion Interaction: The Role of Longitudinal Fields
Quinteiro, G. F.; Schmidt-Kaler, Ferdinand; Schmiegelow, Christian T.
2017-12-01
The propagation of light beams is well described using the paraxial approximation, where field components along the propagation direction are usually neglected. For strongly inhomogeneous or shaped light fields, however, this approximation may fail, leading to intriguing variations of the light-matter interaction. This is the case of twisted light having opposite orbital and spin angular momenta. We compare experimental data for the excitation of a quadrupole transition in a single trapped 40Ca+ ion from Schmiegelow et al. [Nat. Commun. 7, 12998 (2016), 10.1038/ncomms12998] with a complete model where longitudinal components of the electric field are taken into account. Our model matches the experimental data and excludes by 11 standard deviations the approximation of a complete transverse field. This demonstrates the relevance of all field components for the interaction of twisted light with matter.
Nonsnaking doubly diffusive convectons and the twist instability
Energy Technology Data Exchange (ETDEWEB)
Beaume, Cédric, E-mail: ced.beaume@gmail.com; Knobloch, Edgar, E-mail: knobloch@berkeley.edu [Department of Physics, University of California, Berkeley, California 94720 (United States); Bergeon, Alain, E-mail: alain.bergeon@imft.fr [Université de Toulouse, INPT, UPS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France and CNRS, IMFT, F-31400 Toulouse (France)
2013-11-15
Doubly diffusive convection in a three-dimensional horizontally extended domain with a square cross section in the vertical is considered. The fluid motion is driven by horizontal temperature and concentration differences in the transverse direction. When the buoyancy ratio N = −1 and the Rayleigh number is increased the conduction state loses stability to a subcritical, almost two-dimensional roll structure localized in the longitudinal direction. This structure exhibits abrupt growth in length near a particular value of the Rayleigh number but does not snake. Prior to this filling transition the structure becomes unstable to a secondary twist instability generating a pair of stationary, spatially localized zigzag states. In contrast to the primary branch these states snake as they grow in extent and eventually fill the whole domain. The origin of the twist instability and the properties of the resulting localized structures are investigated for both periodic and no-slip boundary conditions in the extended direction.
The dipole representation of vector meson electroproduction beyond leading twist
International Nuclear Information System (INIS)
Besse, A.; Szymanowski, L.; Wallon, S.
2013-01-01
We link the recent computation beyond leading twist of the impact factor of the transition γ T ⁎ →ρ T performed in the light-cone collinear approach, to the dipole picture by expressing the hard part of the process through its Fourier transform in coordinate space. We show that in the Wandzura–Wilczek approximation the impact factor up to twist 3 factorises in the wave function of the photon combined with the distribution amplitudes of the ρ-meson and the colour dipole scattering amplitude with the t-channel gluons. We show also that beyond the Wandzura–Wilczek approximation, the hard contribution of the amplitude still exhibits the signature of the interaction of a single colour dipole with the t-channel gluons. This result allows a phenomenological approach of the helicity amplitudes of the leptoproduction of vector meson, by combining our results to a dipole/target scattering amplitude model.
Electric currents induced by twisted light in Quantum Rings.
Quinteiro, G F; Berakdar, J
2009-10-26
We theoretically investigate the generation of electric currents in quantum rings resulting from the optical excitation with twisted light. Our model describes the kinetics of electrons in a two-band model of a semiconductor-based mesoscopic quantum ring coupled to light having orbital angular momentum (twisted light). We find the analytical solution, which exhibits a "circular" photon-drag effect and an induced magnetization, suggesting that this system is the circular analog of that of a bulk semiconductor excited by plane waves. For realistic values of the electric field and material parameters, the computed electric current can be as large as microA; from an applied perspective, this opens new possibilities to the optical control of the magnetization in semiconductors.
Sweep-twist adaptive rotor blade : final project report.
Energy Technology Data Exchange (ETDEWEB)
Ashwill, Thomas D.
2010-02-01
Knight & Carver was contracted by Sandia National Laboratories to develop a Sweep Twist Adaptive Rotor (STAR) blade that reduced operating loads, thereby allowing a larger, more productive rotor. The blade design used outer blade sweep to create twist coupling without angled fiber. Knight & Carver successfully designed, fabricated, tested and evaluated STAR prototype blades. Through laboratory and field tests, Knight & Carver showed the STAR blade met the engineering design criteria and economic goals for the program. A STAR prototype was successfully tested in Tehachapi during 2008 and a large data set was collected to support engineering and commercial development of the technology. This report documents the methodology used to develop the STAR blade design and reviews the approach used for laboratory and field testing. The effort demonstrated that STAR technology can provide significantly greater energy capture without higher operating loads on the turbine.
Twisted tachyon condensation in closed string field theory
International Nuclear Information System (INIS)
Okawa, Yuji; Zwiebach, Barton
2004-01-01
We consider twisted tachyons on C/Z N orbifolds of bosonic closed string theory. It has been conjectured that these tachyonic instabilities correspond to decays of the orbifolds into flat space or into orbifolds with smaller deficit angles. We examine this conjecture using closed string field theory, with the string field truncated to low-level tachyons. We compute the tachyon potentials for C/Z 2 and C/Z 3 orbifolds and find critical points at depths that generate about 70% of the expected change in the deficit angle. We find that both twisted fields and untwisted modes localized near the apex of the cone acquire vacuum expectation values and contribute to the potential. (author)
Twisted bilayer blue phosphorene: A direct band gap semiconductor
Ospina, D. A.; Duque, C. A.; Correa, J. D.; Suárez Morell, Eric
2016-09-01
We report that two rotated layers of blue phosphorene behave as a direct band gap semiconductor. The optical spectrum shows absorption peaks in the visible region of the spectrum and in addition the energy of these peaks can be tuned with the rotational angle. These findings makes twisted bilayer blue phosphorene a strong candidate as a solar cell or photodetection device. Our results are based on ab initio calculations of several rotated blue phosphorene layers.
Control of Spin Wave Dynamics in Spatially Twisted Magnetic Structures
2017-06-27
control the spin wave dynamics of magnetic structures twisted spatially, we prepared the exchange-coupled films with the hard magnetic L10-FePt and...information writing of magnetic storage and spintronic applications. Introduction and Objective: Recent rapid progress in the research field of nano...scaled bilayer elements is also an important aim of this project. Approach/Method: The exchange-coupled films with the hard magnetic L10-FePt and
Some new quasi-twisted ternary linear codes
Directory of Open Access Journals (Sweden)
Rumen Daskalov
2015-09-01
Full Text Available Let [n, k, d]_q code be a linear code of length n, dimension k and minimum Hamming distance d over GF(q. One of the basic and most important problems in coding theory is to construct codes with best possible minimum distances. In this paper seven quasi-twisted ternary linear codes are constructed. These codes are new and improve the best known lower bounds on the minimum distance in [6].
Topological susceptibility from twisted mass fermions using spectral projectors
Energy Technology Data Exchange (ETDEWEB)
Cichy, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Garcia-Ramos, E. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Shindler, A. [Forschungszentrum Juelich (Germany). IAS; Forschungszentrum Juelich (Germany). IKP; Forschungszentrum Juelich (Germany). JCHP; Collaboration: European Twisted Mass Collaboration
2013-12-15
We discuss the computation of the topological susceptibility using the method of spectral projectors and dynamical twisted mass fermions. We present our analysis concerning the O(a)- improvement of the topological susceptibility and we show numerical results for N{sub f}=2 and N{sub f}=2+1+1 flavours, performing a study of the quark mass dependence in terms of leading order chiral perturbation theory.
Leading Twist GPDs and Transverse Spin Densities in a Proton
Mondal, Chandan; Maji, Tanmay; Chakrabarti, Dipankar; Zhao, Xingbo
2018-05-01
We present a study of both chirally even and odd generalized parton distributions in the leading twist for the quarks in a proton using the light-front wavefunctions of a quark-diquark model predicted by the holographic QCD. For transversely polarized proton, both chiral even and chiral odd GPDs contribute to the spin densities which are related to the GPDs in transverse impact parameter space. Here, we also present a study of the spin densities for transversely polarized quark and proton.
Twisted boundary states and representation of generalized fusion algebra
International Nuclear Information System (INIS)
Ishikawa, Hiroshi; Tani, Taro
2006-01-01
The mutual consistency of boundary conditions twisted by an automorphism group G of the chiral algebra is studied for general modular invariants of rational conformal field theories. We show that a consistent set of twisted boundary states associated with any modular invariant realizes a non-negative integer matrix representation (NIM-rep) of the generalized fusion algebra, an extension of the fusion algebra by representations of the twisted chiral algebra associated with the automorphism group G. We check this result for several concrete cases. In particular, we find that two NIM-reps of the fusion algebra for su(3) k (k=3,5) are organized into a NIM-rep of the generalized fusion algebra for the charge-conjugation automorphism of su(3) k . We point out that the generalized fusion algebra is non-commutative if G is non-Abelian and provide some examples for G-bar S 3 . Finally, we give an argument that the graph fusion algebra associated with simple current extensions coincides with the generalized fusion algebra for the extended chiral algebra, and thereby explain that the graph fusion algebra contains the fusion algebra of the extended theory as a subalgebra
Unwinding motion of a twisted active region filament
Energy Technology Data Exchange (ETDEWEB)
Yan, X. L.; Xue, Z. K.; Kong, D. F. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, J. H. [Department of Physics, Shijiazhuang University, Shijiazhuang 050035 (China); Xu, C. L. [Yunnan Normal University, Kunming 650092 (China)
2014-12-10
To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.
Microwave modulation characteristics of twisted liquid crystals with chiral dopant
Directory of Open Access Journals (Sweden)
Rui Yuan
2017-01-01
Full Text Available Adding a chiral dopant in twisted nematic (TN liquid crystal cell can stabilize the orientation of liquid crystal molecules, particularly in high TN (HTN or super TN (STN liquid crystal cells. The difference in pitches in liquid crystal is induced by the chiral dopant, and these different pitches affect the orientation of liquid crystal director under an external applied voltage and influence the characteristics of microwave modulation. To illustrate this point, the microwave phase shift per unit length (MPSL versus voltage is calculated on the basis of the elastic theory of liquid crystal and the finite-difference iterative method. Enhancing the pitch induced by the chiral dopant in liquid crystal increases the MPSLs, but the stability of the twisted structures is decreased. Thus, appropriate pitches of 100d, 4d, and 2d can be applied in TN, HTN, and STN cells with cell gap d to enhance the characteristics of microwave modulation and stabilize the structures in twisted cell. This method can improve the characteristics of liquid crystal microwave modulators such that the operating voltage and the size of such phase shifters can be decreased.
Twisted Bilayer Graphene. Interlayer configuration and magnetotransport signatures
Energy Technology Data Exchange (ETDEWEB)
Rode, Johannes C.; Smirnov, Dmitri; Belke, Christopher; Schmidt, Hennrik; Haug, Rolf J. [Institut fuer Festkoerperphysik, Hannover (Germany)
2017-11-15
Twisted Bilayer Graphene may be viewed as very first representative of the now booming class of artificially layered 2D materials. Consisting of two sheets from the same structure and atomic composition, its decisive degree of freedom lies in the rotation between crystallographic axes in the individual graphene monolayers. Geometrical consideration finds angle-dependent Moire patterns as well as commensurate superlattices of opposite sublattice exchange symmetry. Beyond the approach of rigidly interposed lattices, this review takes focus on the evolving topic of lattice corrugation and distortion in response to spatially varying lattice registry. The experimental approach to twisted bilayers requires a basic control over preparation techniques; important methods are summarized and extended on in the case of bilayers folded from monolayer graphene via AFM nanomachining. Central morphological parameters to the twisted bilayer, rotational mismatch and interlayer separation are studied in a broader base of samples. Finally, experimental evidence for a number of theoretically predicted, controversial electronic scenarios are reviewed; magnetotransport signatures are discussed in terms of Fermi velocity, van Hove singularities and Berry phase and assessed with respect to the underlying experimental conditions, thereby referring back to the initially considered variations in relaxed lattice structure. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Wrinkles, loops, and topological defects in twisted ribbons
Chopin, Julien
Nature abounds with elastic ribbon like shapes including double-stranded semiflexible polymers, graphene and metal oxide nanoribbons which are examples of elongated elastic structures with a strongly anisotropic cross-section. Due to this specific geometry, it is far from trivial to anticipate if a ribbon should be considered as a flat flexible filament or a narrow thin plate. We thus perform an experiment in which a thin elastic ribbon is loaded using a twisting and traction device coupled with a micro X-ray computed tomography machine allowing a full 3D shape reconstruction. A wealth of morphological behaviors can be observed including wrinkled helicoids, curled and looped configurations, and faceted ribbons. In this talk, I will show that most morphologies can be understood using a far-from-threshold approach and simple scaling arguments. Further, we find that the various shapes can be organized in a phase diagram using the twist, the tension, and the geometry of the ribbon as control parameters. Finally, I will discuss the spontaneous formation of topological defects with negatively-signed Gaussian charge at large twist and small but finite stretch.
'Twisted tape sign': Its significance in recurrent sigmoid volvulus
International Nuclear Information System (INIS)
Gopal, K.; Lim, Y.; Banerjee, B.
2005-01-01
Aim: Sigmoid volvulus is a common cause of intestinal obstruction in the elderly. Mild attacks of sigmoid volvulus may be more difficult to diagnose due to the lack of severity of symptoms which may resolve spontaneously only to recur after an interval. This study was a review of patients to assess the incidence of the 'twisted tape sign' and to evaluate the significance of its presence in cases of recurrent sigmoid volvulus. Methods and materials: A retrospective study over eight years revealed six cases of surgically confirmed recurrent sigmoid volvulus. Case records and barium enemas of all patients were reviewed. Results: Six patients were identified, including four men and two women, with a median age of 56 years. Diagnostic difficulties were encountered in four (67%) patients with a delay ranging between 10 and 37 months with a mean 17.3 months. Twisted tape sign was confirmed on all barium examinations retrospectively. Conclusion: Recognition of twisted tape sign on barium enema examination along with an appropriate clinical history would suggest a diagnosis of recurrent sigmoid volvulus
Twist effects in quantum vortices and phase defects
Zuccher, Simone; Ricca, Renzo L.
2018-02-01
In this paper we show that twist, defined in terms of rotation of the phase associated with quantum vortices and other physical defects effectively deprived of internal structure, is a property that has observable effects in terms of induced axial flow. For this we consider quantum vortices governed by the Gross-Pitaevskii equation (GPE) and perform a number of test cases to investigate and compare the effects of twist in two different contexts: (i) when this is artificially superimposed on an initially untwisted vortex ring; (ii) when it is naturally produced on the ring by the simultaneous presence of a central straight vortex. In the first case large amplitude perturbations quickly develop, generated by the unnatural setting of the initial condition that is not an analytical solution of the GPE. In the second case much milder perturbations emerge, signature of a genuine physical process. This scenario is confirmed by other test cases performed at higher twist values. Since the second setting corresponds to essential linking, these results provide new evidence of the influence of topology on physics.
Enhancement of turbulent flow heat transfer in a tube with modified twisted tapes
Energy Technology Data Exchange (ETDEWEB)
Lei, Y.G.; Zhao, C.H.; Song, C.F. [College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan (China)
2012-12-15
Numerical simulations were performed to study the fluid flow and heat transfer in a tube with staggered twisted tapes with central holes. In the range of Reynolds numbers between 6000 and 28 000, the modified twisted tapes increased the Nusselt number by 76.2 {proportional_to} 149.7 % and the friction factor by 380.2 {proportional_to} 443.8 % compared to the smooth tube. Compared to the typical twisted tapes, the modified twisted tapes produced an acceleration flow through the triangle regions leading to the enhancement of heat transfer, and the holes in the modified tapes reduced the severe pressure loss. It was found that the modified twisted tapes decreased the friction factor by 8.0 {proportional_to} 16.1 % and enhanced the heat transfer by 34.1 {proportional_to} 46.8 % in comparison with the typical tapes. These results indicated that the performance ratio values of the tube with modified twisted tapes were higher than 1.0 in the range of Reynolds numbers studied. The computed performance ratios of the tube with modified twisted tapes were much higher than those of the tube with typical twisted tapes. This means that the integrated performance of the tube with staggered twisted tapes with central holes is superior to that of the tube with typical twisted tapes. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Directory of Open Access Journals (Sweden)
Phuoc T Tran
Full Text Available KRAS mutant lung cancers are generally refractory to chemotherapy as well targeted agents. To date, the identification of drugs to therapeutically inhibit K-RAS have been unsuccessful, suggesting that other approaches are required. We demonstrate in both a novel transgenic mutant Kras lung cancer mouse model and in human lung tumors that the inhibition of Twist1 restores a senescence program inducing the loss of a neoplastic phenotype. The Twist1 gene encodes for a transcription factor that is essential during embryogenesis. Twist1 has been suggested to play an important role during tumor progression. However, there is no in vivo evidence that Twist1 plays a role in autochthonous tumorigenesis. Through two novel transgenic mouse models, we show that Twist1 cooperates with Kras(G12D to markedly accelerate lung tumorigenesis by abrogating cellular senescence programs and promoting the progression from benign adenomas to adenocarcinomas. Moreover, the suppression of Twist1 to physiological levels is sufficient to cause Kras mutant lung tumors to undergo senescence and lose their neoplastic features. Finally, we analyzed more than 500 human tumors to demonstrate that TWIST1 is frequently overexpressed in primary human lung tumors. The suppression of TWIST1 in human lung cancer cells also induced cellular senescence. Hence, TWIST1 is a critical regulator of cellular senescence programs, and the suppression of TWIST1 in human tumors may be an effective example of pro-senescence therapy.
Energy Technology Data Exchange (ETDEWEB)
Szymanowski, Lech [Soltan Institute for Nuclear Studies, Hoza 69, 00691, Warsaw (Poland); Anikin, Igor V. [Joint Institute for Nuclear Research - JINR, Joliot-Curie st., 6, Moskovskaya obl., 141980, Dubna (Russian Federation); Ivanov, Dmitry Yu [Sobolev Institute of Mathematics, Acad. Koptyug pr., 4, 630090 Novosibirsk (Russian Federation); Pire, Bernard [Centre de Physique Theorique - CPHT, UMR 7644, Ecole Polytechnique, Bat. 6, RDC, F91128 Palaiseau Cedex (France); Wallon, Samuel [Laboratoire de Physique Theorique d' Orsay - LPT, Bat. 210, Univ. Paris-Sud 11, 91405 Orsay Cedex (France)
2010-07-01
We describe a consistent approach to factorization of scattering amplitudes for exclusive processes beyond the leading twist approximation. The method is based on the Taylor expansion of the scattering amplitude in the momentum space around the dominant light-cone direction and thus naturally introduces an appropriate set of non-perturbative correlators which encode effects not only of the lowest but also of the higher Fock states of the produced particle. The reduction of original set of correlators to a set of independent ones is achieved with the help of equations of motion and invariance of the scattering amplitude under rotation on the light-cone. As a concrete application, we compute the expressions of the impact factor for the transition of virtual photon to transversally polarised {rho}-meson up to the twist 3 accuracy. (Phys.Lett.B682:413-418,2010 and Nucl.Phys.B828:1-68,2010.). (authors)
Integral Twist Actuation of Helicopter Rotor Blades for Vibration Reduction
Shin, SangJoon; Cesnik, Carlos E. S.
2001-01-01
Active integral twist control for vibration reduction of helicopter rotors during forward flight is investigated. The twist deformation is obtained using embedded anisotropic piezocomposite actuators. An analytical framework is developed to examine integrally-twisted blades and their aeroelastic response during different flight conditions: frequency domain analysis for hover, and time domain analysis for forward flight. Both stem from the same three-dimensional electroelastic beam formulation with geometrical-exactness, and axe coupled with a finite-state dynamic inflow aerodynamics model. A prototype Active Twist Rotor blade was designed with this framework using Active Fiber Composites as the actuator. The ATR prototype blade was successfully tested under non-rotating conditions. Hover testing was conducted to evaluate structural integrity and dynamic response. In both conditions, a very good correlation was obtained against the analysis. Finally, a four-bladed ATR system is built and tested to demonstrate its concept in forward flight. This experiment was conducted at NASA Langley Tansonic Dynamics Tunnel and represents the first-of-a-kind Mach-scaled fully-active-twist rotor system to undergo forward flight test. In parallel, the impact upon the fixed- and rotating-system loads is estimated by the analysis. While discrepancies are found in the amplitude of the loads under actuation, the predicted trend of load variation with respect to its control phase correlates well. It was also shown, both experimentally and numerically, that the ATR blade design has the potential for hub vibratory load reduction of up to 90% using individual blade control actuation. Using the numerical framework, system identification is performed to estimate the harmonic transfer functions. The linear time-periodic system can be represented by a linear time-invariant system under the three modes of blade actuation: collective, longitudinal cyclic, and lateral cyclic. A vibration
Effect of Twisting and Stretching on Magneto Resistance and Spin Filtration in CNTs
Directory of Open Access Journals (Sweden)
Anil Kumar Singh
2017-08-01
Full Text Available Spin-dependent quantum transport properties in twisted carbon nanotube and stretched carbon nanotube are calculated using density functional theory (DFT and non-equilibrium green’s function (NEGF formulation. Twisting and stretching have no effect on spin transport in CNTs at low bias voltages. However, at high bias voltages the effects are significant. Stretching restricts any spin-up current in antiparallel configuration (APC, which results in higher magneto resistance (MR. Twisting allows spin-up current almost equivalent to the pristine CNT case, resulting in lower MR. High spin filtration is observed in PC and APC for pristine, stretched and twisted structures at all applied voltages. In APC, at low voltages spin filtration in stretched CNT is higher than in pristine and twisted ones, with pristine giving a higher spin filtration than twisted CNT.
Twisted entire cyclic cohomology, J-L-O cocycles and equivariant spectral triples
International Nuclear Information System (INIS)
Goswami, D.
2002-07-01
We study the 'quantized calculus' corresponding to the algebraic ideas related to 'twisted cyclic cohomology'. With very similar definitions and techniques, we define and study 'twisted entire cyclic cohomology' and the 'twisted Chern character' associated with an appropriate operator theoretic data called 'twisted spectral data', which consists of a spectral triple in the conventional sense of noncommutative geometry and an additional positive operator having some specified properties. Furthermore, it is shown that given a spectral triple (in the conventional sense) which is equivariant under the action of a compact matrix pseudogroup, it is possible to obtain a canonical twisted spectral data and hence the corresponding (twisted) Chern character, which will be invariant under the action of the pseudogroup, in contrast to the fact that the Chern character coming from the conventional noncommutative geometry need not be invariant under the above action. (author)
Directory of Open Access Journals (Sweden)
K. SYED JAFAR
2017-03-01
Full Text Available In this paper, the experimental heat transfer, friction loss and thermal performance data for water flowing through the absorber tube fitted with two different twisted tape configurations in parabolic trough collector (PTC are presented. In the present work, a relative experimental study is carried out to investigate the performance of a PTC influenced by heat transfer through fluidabsorber wall mixing mechanism. The major findings of this experiment show that heat transport enhancement in the nail twisted tape collector perform significantly better than plain twisted tapes and also show that the smallest twisted tape ratio enhances the system performance remarkably maximizing the collector efficiency. The results suggest that the twisted tape and nail twisted tape would be a better option for high thermal energy collection in laminar region of the PTC system.
Performance improvement of small-scale rotors by passive blade twist control
Lv, Peng; Prothin, Sebastien; Mohd Zawawi, Fazila; Bénard, Emmanuel; Morlier, Joseph; Moschetta, Jean-Marc
2015-01-01
A passive twist control is proposed as an adaptive way to maximize the overall efficiency of the small-scale rotor blade for multifunctional aircrafts. Incorporated into a database of airfoil characteristics, Blade Element Momentum Theory is implemented to obtain the blade optimum twist rates for hover and forward flight. In order to realize the required torsion of blade between hover and forward flight, glass/epoxy laminate blade is proposed based on Centrifugal Force Induced Twist concept. ...
Higher-Twist Distribution Amplitudes of the K Meson in QCD
Ball, P; Lenz, A; Ball, Patricia
2006-01-01
We present a systematic study of twist-3 and twist-4 light-cone distribution amplitudes of the K meson in QCD. The structure of SU(3)-breaking corrections is studied in detail. Non-perturbative input parameters are estimated from QCD sum rules and renormalons. As a by-product, we give a complete reanalysis of the twist-3 and -4 parameters of the pi-meson distribution amplitudes; some of the results differ from those usually quoted in the literature.
Harfe, Brian D.; Gomes, Ana Vaz; Kenyon, Cynthia; Liu, Jun; Krause, Michael; Fire, Andrew
1998-01-01
Mesodermal development is a multistep process in which cells become increasingly specialized to form specific tissue types. In Drosophila and mammals, proper segregation and patterning of the mesoderm involves the bHLH factor Twist. We investigated the activity of a Twist-related factor, CeTwist, during Caenorhabditis elegans mesoderm development. Embryonic mesoderm in C. elegans derives from a number of distinct founder cells that are specified during the early lineages; in contrast, a singl...
Electrical transport properties of an isolated CdS microrope composed of twisted nanowires.
Yu, Gui-Feng; Yu, Miao; Pan, Wei; Han, Wen-Peng; Yan, Xu; Zhang, Jun-Cheng; Zhang, Hong-Di; Long, Yun-Ze
2015-01-01
CdS is one of the important II-VI group semiconductors. In this paper, the electrical transport behavior of an individual CdS microrope composed of twisted nanowires is studied. It is found that the current-voltage (I-V) characteristics show two distinct power law regions from 360 down to 60 K. Space-charge-limited current (SCLC) theory is used to explain these temperature- and electric-field-dependent I-V curves. The I-V data can be well fitted by this theory above 100 K, and the corresponding carrier mobility, trap energy, and trap concentration are also obtained. However, the I-V data exhibit some features of the Coulomb blockade effect below 80 K.
Electrical transport properties of an isolated CdS microrope composed of twisted nanowires
Yu, Gui-Feng; Yu, Miao; Pan, Wei; Han, Wen-Peng; Yan, Xu; Zhang, Jun-Cheng; Zhang, Hong-Di; Long, Yun-Ze
2015-01-01
CdS is one of the important II-VI group semiconductors. In this paper, the electrical transport behavior of an individual CdS microrope composed of twisted nanowires is studied. It is found that the current-voltage ( I- V) characteristics show two distinct power law regions from 360 down to 60 K. Space-charge-limited current (SCLC) theory is used to explain these temperature- and electric-field-dependent I-V curves. The I-V data can be well fitted by this theory above 100 K, and the corresponding carrier mobility, trap energy, and trap concentration are also obtained. However, the I-V data exhibit some features of the Coulomb blockade effect below 80 K.
Baryon spectrum with Nƒ=2+1+1 twisted mass fermions
DEFF Research Database (Denmark)
Alexandrou, C.; Drach, V.; Jansen, K.
2014-01-01
The masses of the low-lying baryons are evaluated using a total of ten ensembles of dynamical twisted mass fermion gauge configurations. The simulations are performed using two degenerate flavors of light quarks, and a strange and a charm quark fixed to approximately their physical values....... The light sea quarks correspond to pseudo scalar masses in the range of about 210 to 430 MeV. We use the Iwasaki improved gluonic action at three values of the coupling constant corresponding to lattice spacing a = 0.094, 0.082 and 0.065 fm determined from the nucleon mass. We check for both finite volume...... and cutoff effects on the baryon masses. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. We performed a chiral extrapolation of the forty...
Energy Technology Data Exchange (ETDEWEB)
Guzey, Vadim; Goeke, Klaus; Siddikov, Marat
2009-01-01
We generalize the leading twist theory of nuclear shadowing and calculate quark and gluon generalized parton distributions (GPDs) of spinless nuclei. We predict very large nuclear shadowing for nuclear GPDs. In the limit of the purely transverse momentum transfer, our nuclear GPDs become impact parameter dependent nuclear parton distributions (PDFs). Nuclear shadowing induces non-trivial correlations between the impact parameter $b$ and the light-cone fraction $x$. We make predictions for the deeply virtual Compton scattering (DVCS) amplitude and the DVCS cross section on $^{208}$Pb at high energies. We calculate the cross section of the Bethe-Heitler (BH) process and address the issue of the extraction of the DVCS signal from the $e A \\to e \\gamma A$ cross section. We find that the $e A \\to e \\gamma A$ differential cross section is dominated by DVCS at the momentum transfer $t$ near the minima of the nuclear form factor. We also find that nuclear shadowing leads
'Duality twisted'boundary conditions in n-state Potts Models
International Nuclear Information System (INIS)
Schuetz, G.
1992-11-01
We discuss a new class of toroidal boundary conditions for one-dimensional quantum Hamiltonian with S n symmetry which are related to two-dimensional n-state Potts models in the extreme anisotropic Hamiltonian limit. At their self-dual point (a point were a second-order phase transition occurs for n=2,3,4) the duality transformation is shown to be an additional symmetry giving rise to a new class of 'duality twisted' toroidal boundary conditions. This corresponding Hamiltonians are given in terms of generators of the periodic Temprely-Lieb algebra with an odd number of generators. We discuss as an example the critical Ising model. Here the complete spectrum for the new boundary conditions can be obtained from a projection mechanism in the spin-1/2 XXZ Heisenberg chain. (author)
Measurement of curvature and twist of a deformed object using digital holography
International Nuclear Information System (INIS)
Chen Wen; Quan Chenggen; Cho Jui Tay
2008-01-01
Measurement of curvature and twist is an important aspect in the study of object deformation. In recent years, several methods have been proposed to determine curvature and twist of a deformed object using digital shearography. Here we propose a novel method to determine the curvature and twist of a deformed object using digital holography and a complex phasor. A sine/cosine transformation method and two-dimensional short time Fourier transform are proposed subsequently to process the wrapped phase maps. It is shown that high-quality phase maps corresponding to curvature and twist can be obtained. An experiment is conducted to demonstrate the validity of the proposed method
A method to estimate the necessary twist pitch in multi-filamentary superconductors
International Nuclear Information System (INIS)
Lindau, S; Magnusson, N; Taxt, H
2014-01-01
Twisting of multi-filamentary superconductors is an important step in the development of wires with AC losses at an acceptable level for AC applications. The necessary twist pitch depends on wire architecture, critical current density, matrix material, and external factors such as temperature, frequency and applied magnetic field. The development of an AC optimized MgB 2 superconductor would be facilitated by a fast method to set the requirements for the twist pitch. A problem often encountered when comparing wires with different twist pitches is the degradation in critical current occurring at small twist pitches due to mechanical deformation. In this work we propose to use a non-twisted conductor to estimate the influence of twisting on the AC losses. A long superconductor is cut into smaller lengths, each simulating one third of the twist pitch, and the AC losses due to applied magnetic fields are compared between samples of different lengths. With this method, the effect of reducing the size of the loop of the coupling currents is studied without changing the superconducting parameters. AC loss measurement results are presented for a round titanium matrix MgB 2 wire with simulated twist pitches between 9 mm and 87 mm.
Dynamical twisted mass fermions with light quarks. Simulation and analysis details
International Nuclear Information System (INIS)
Boucaud, P.; Dimopoulos, P.; Farchioni, F.
2008-03-01
In a recent paper (2007) we presented precise lattice QCD results of our European Twisted Mass Collaboration (ETMC). They were obtained by employing two mass-degenerate flavours of twisted mass fermions at maximal twist. In the present paper we give details on our simulations and the computation of physical observables. In particular, we discuss the problem of tuning to maximal twist, the techniques we have used to compute correlators and error estimates. In addition, we provide more information on the algorithm used, the autocorrelation times and scale determination, the evaluation of disconnected contributions and the description of our data by means of chiral perturbation theory formulae. (orig.)
Dynamical twisted mass fermions with light quarks. Simulation and analysis details
Energy Technology Data Exchange (ETDEWEB)
Boucaud, P. [Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique; Dimopoulos, P. [Rome-2 Univ. (Italy). Dipt. di Fisica; Farchioni, F. [Muenster Univ. (DE). Inst. fuer Theoretische Physik] (and others)
2008-03-15
In a recent paper (2007) we presented precise lattice QCD results of our European Twisted Mass Collaboration (ETMC). They were obtained by employing two mass-degenerate flavours of twisted mass fermions at maximal twist. In the present paper we give details on our simulations and the computation of physical observables. In particular, we discuss the problem of tuning to maximal twist, the techniques we have used to compute correlators and error estimates. In addition, we provide more information on the algorithm used, the autocorrelation times and scale determination, the evaluation of disconnected contributions and the description of our data by means of chiral perturbation theory formulae. (orig.)
Neutron electric dipole moment using N{sub f}=2+1+1 twisted mass fermions
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, C.; Athenodorou, A.; Constantinou, M.; Hadjiyiannakou, K. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Koutsou, G. [The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Ottnad, K. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Bonn Univ. (Germany). Helmholtz-Institut fuer Strahlen- und Kernphysik; Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Petschlies, M. [The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Bonn Univ. (Germany). Helmholtz-Institut fuer Strahlen- und Kernphysik; Bonn Univ. (Germany). Bethe Center for Theoretical Physics
2016-03-15
We evaluate the neutron electric dipole moment vertical stroke vector d{sub N} vertical stroke using lattice QCD techniques. The gauge configurations analyzed are produced by the European Twisted Mass Collaboration using N{sub f}=2+1+1 twisted mass fermions at one value of the lattice spacing of a ≅0.082 fm and a light quark mass corresponding to m{sub π}≅373 MeV. Our approach to extract the neutron electric dipole moment is based on the calculation of the CP-odd electromagnetic form factor F{sub 3}(Q{sup 2}) for small values of the vacuum angle θ in the limit of zero Euclidean momentum transfer Q{sup 2}. The limit Q{sup 2}→0 is realized either by adopting a parameterization of the momentum dependence of F{sub 3}(Q{sup 2}) and performing a fit, or by employing new position space methods, which involve the elimination of the kinematical momentum factor in front of F{sub 3}(Q{sup 2}). The computation in the presence of a CP-violating term requires the evaluation of the topological charge Q. This is computed by applying the cooling technique and the gradient flow with three different actions, namely the Wilson, the Symanzik tree-level improved and the Iwasaki action. We demonstrate that cooling and gradient flow give equivalent results for the neutron electric dipole moment. Our analysis yields a value of vertical stroke vector d{sub N} vertical stroke =0.045(6)(1) anti θ e.fm for the ensemble with m{sub π}=373 MeV considered.
Chiral condensate from the twisted mass Dirac operator spectrum
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Collaboration: European Twisted Mass Collaboration
2013-03-15
We present the results of our computation of the chiral condensate with N{sub f}=2 and N{sub f}=2+1+1 flavours of maximally twisted mass fermions. The condensate is determined from the Dirac operator spectrum, applying the spectral projector method proposed by Giusti and Luescher. We use 3 lattice spacings and several quark masses at each lattice spacing to reliably perform the chiral and continuum extrapolations. We study the effect of the dynamical strange and charm quarks by comparing our results for N{sub f}=2 and N{sub f}=2+1+1 dynamical flavours.
Position Control of Switched Reluctance Motor Using Super Twisting Algorithm
Directory of Open Access Journals (Sweden)
Muhammad Rafiq Mufti
2016-01-01
Full Text Available The inherent problem of chattering in traditional sliding mode control is harmful for practical application of control system. This paper pays a considerable attention to a chattering-free control method, that is, higher-order sliding mode (super twisting algorithm. The design of a position controller for switched reluctance motor is presented and its stability is assured using Lyapunov stability theorem. In order to highlight the advantages of higher-order sliding mode controller (HOSMC, a classical first-order sliding mode controller (FOSMC is also applied to the same system and compared. The simulation results reflect the effectiveness of the proposed technique.
Twisting, supercoiling and stretching in protein bound DNA
Lam, Pui-Man; Zhen, Yi
2018-04-01
We have calculated theoretical results for the torque and slope of the twisted DNA, with various proteins bound on it, using the Neukirch-Marko model, in the regime where plectonemes exist. We found that the torque in the protein bound DNA decreases compared to that in the bare DNA. This is caused by the decrease in the free energy g(f) , and hence the smaller persistence lengths, in the case of protein bound DNA. We hope our results will encourage experimental investigations of supercoiling in protein bound DNA, which can provide further tests of the Neukirch-Marko model.
Analysis of the British Industrial Revolution in cinema: Oliver Twist
Fuente Diez, Óscar
2015-01-01
La Revolución Industrial británica fue un fenómeno histórico que incluso a día de hoy continúa atrayendo miradas. Sus dimensiones fueron tales que actualmente sus consecuencias aún son visibles. El objetivo de este proyecto es analizar el impacto social de la Revolución Industrial británica y las causas que llevaron a este punto como retrata Oliver Twist, la película seleccionada. Desde la perspectiva de las injusticias laborales y las desigualdades sociales, el estudio se centra en las conse...
Chiral condensate from the twisted mass Dirac operator spectrum
International Nuclear Information System (INIS)
Cichy, Krzysztof; Jansen, Karl; Cyprus Univ., Nicosia
2013-03-01
We present the results of our computation of the chiral condensate with N f =2 and N f =2+1+1 flavours of maximally twisted mass fermions. The condensate is determined from the Dirac operator spectrum, applying the spectral projector method proposed by Giusti and Luescher. We use 3 lattice spacings and several quark masses at each lattice spacing to reliably perform the chiral and continuum extrapolations. We study the effect of the dynamical strange and charm quarks by comparing our results for N f =2 and N f =2+1+1 dynamical flavours.
Wigner oscillators, twisted Hopf algebras and second quantization
Energy Technology Data Exchange (ETDEWEB)
Castro, P.G.; Toppan, F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mails: pgcastro@cbpf.br; toppan@cbpf.br; Chakraborty, B. [S. N. Bose National Center for Basic Sciences, Kolkata (India)]. E-mail: biswajit@bose.res.in
2008-07-01
By correctly identifying the role of central extension in the centrally extended Heisenberg algebra h, we show that it is indeed possible to construct a Hopf algebraic structure on the corresponding enveloping algebra U(h) and eventually deform it through Drinfeld twist. This Hopf algebraic structure and its deformed version U{sup F}(h) is shown to be induced from a more 'fundamental' Hopf algebra obtained from the Schroedinger field/oscillator algebra and its deformed version, provided that the fields/oscillators are regarded as odd-elements of a given superalgebra. We also discuss the possible implications in the context of quantum statistics. (author)
Twisted speckle entities inside wave-front reversal mirrors
International Nuclear Information System (INIS)
Okulov, A. Yu
2009-01-01
The previously unknown property of the optical speckle pattern reported. The interference of a speckle with the counterpropagating phase-conjugated (PC) speckle wave produces a randomly distributed ensemble of a twisted entities (ropes) surrounding optical vortex lines. These entities appear in a wide range of a randomly chosen speckle parameters inside the phase-conjugating mirrors regardless to an internal physical mechanism of the wave-front reversal. These numerically generated interference patterns are relevant to the Brillouin PC mirrors and to a four-wave mixing PC mirrors based upon laser trapped ultracold atomic cloud.
ABOUT THE GEOMETRY AND THE APPLICATIONS OF THE TWISTED SURFACES
Directory of Open Access Journals (Sweden)
MÂRZA Carmen
2015-06-01
Full Text Available The helical and spiral surfaces are used in various fields. These surfaces are obtained by rotating a segment line called generatrix around directrices lines, respectively the spiral surfaces are obtained by composing simultaneously the movements of translation and rotation of a plane figure around an axis - which can be a straight line or a curved line, or around a real or imaginary surface - called core. After an overview of these surfaces, the attention of the authors will be focused on the geometrical and graphical analysis of the twisted surfaces in civil engineering branch, such as: columns, helical ramps and stairs, respectively buildings having a futuristic design.
Compactifications of 5d SCFTs with a twist
Energy Technology Data Exchange (ETDEWEB)
Zafrir, Gabi [Department of Physics, Technion - Israel Institute of Technology,32000, Haifa (Israel)
2017-01-23
We study the compactification of 5d SCFTs to 4d on a circle with a twist in a discrete global symmetry element of these SCFTs. We present evidence that this leads to various 4dN=2 isolated SCFTs. These include many known theories as well as seemingly new ones. The known theories include the recently discovered rank 1SU(4) SCFT and its mass deformations. One application of the new SCFTs is in the dual descriptions of the 4d gauge theory SU(N)+1S+(N−2)F. Also interesting is the appearance of a theory with rank 1 and F{sub 4} global symmetry.
Light meson physics from maximally twisted mass lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Baron, R.; Boucaud, P. [Paris XI Univ., 91 - Orsay (France). Lab. de Physique Theorique; Dimopoulos, P. [Roma Tor Vergata Univ. (Italy). Dipt. di Fisica; INFN, Rome (IT)] (and others)
2009-12-15
We present a comprehensive investigation of light meson physics using maximally twisted mass fermions for N{sub f}=2 mass-degenerate quark flavours. By employing four values of the lattice spacing, spatial lattice extents ranging from 2.0 fm to 2.5 fm and pseudo scalar masses in the range 280
Light meson physics from maximally twisted mass lattice QCD
International Nuclear Information System (INIS)
Baron, R.; Boucaud, P.
2009-12-01
We present a comprehensive investigation of light meson physics using maximally twisted mass fermions for N f =2 mass-degenerate quark flavours. By employing four values of the lattice spacing, spatial lattice extents ranging from 2.0 fm to 2.5 fm and pseudo scalar masses in the range 280 PS < or similar 650 MeV we control the major systematic effects of our calculation. This enables us to confront our data with chiral perturbation theory and extract low energy constants of the effective chiral Lagrangian and derived quantities, such as the light quark mass, with high precision. (orig.)
Nucleon form factors with NF=2 twisted mass fermions
International Nuclear Information System (INIS)
Alexandrou, C.; Korzec, T.; Brinet, M.; Carbonell, J.; Harraud, P.A.; Jansen, K.
2009-10-01
We present results on the electromagnetic and axial nucleon form factors using two degenerate flavors of twisted mass fermions on lattices of spatial size 2.1 fm and 2.7 fm and a lattice spacing of about 0.09 fm. We consider pion masses in the range of 260-470MeV.We chirally extrapolate results on the nucleon axial charge, the isovector Dirac and Pauli root mean squared radii and magnetic moment to the physical point and compare to experiment. (orig.)
The gradient flow running coupling with twisted boundary conditions
International Nuclear Information System (INIS)
Ramos, Alberto
2014-09-01
We study the gradient flow for Yang-Mills theories with twisted boundary conditions. The perturbative behavior of the energy density left angle E(t) right angle is used to define a running coupling at a scale given by the linear size of the finite volume box. We compute the non-perturbative running of the pure gauge SU(2) coupling constant and conclude that the technique is well suited for further applications due to the relatively mild cutoff effects of the step scaling function and the high numerical precision that can be achieved in lattice simulations. We also comment on the inclusion of matter fields.
Twisting dirac fermions: circular dichroism in bilayer graphene
Suárez Morell, E.; Chico, Leonor; Brey, Luis
2017-09-01
Twisted bilayer graphene is a chiral system which has been recently shown to present circular dichroism. In this work we show that the origin of this optical activity is the rotation of the Dirac fermions’ helicities in the top and bottom layer. Starting from the Kubo formula, we obtain a compact expression for the Hall conductivity that takes into account the dephasing of the electromagnetic field between the top and bottom layers and gathers all the symmetries of the system. Our results are based in both a continuum and a tight-binding model, and they can be generalized to any two-dimensional Dirac material with a chiral stacking between layers.
Five-loop anomalous dimension of twist-two operators
Energy Technology Data Exchange (ETDEWEB)
Lukowski, T. [Institute of Physics, Jagellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Rej, A. [Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom); Velizhanin, V.N., E-mail: velizh@mail.desy.d [Theoretical Physics Department, Petersburg Nuclear Physics Institute, Orlova Roscha, Gatchina, 188300 St. Petersburg (Russian Federation)
2010-05-21
In this article we calculate the five-loop anomalous dimension of twist-two operators in the planar N=4 SYM theory. Firstly, using reciprocity, we derive the contribution of the asymptotic Bethe ansatz. Subsequently, we employ the first finite-size correction for the AdS{sub 5}xS{sup 5} sigma model to determine the wrapping correction. The anomalous dimension found in this way passes all known tests provided by the NLO BFKL equation and double-logarithmic constraints. This result thus furnishes an infinite number of experimental data for testing the veracity of the recently proposed spectral equations for planar AdS/CFT correspondence.
Traveling waves in twisted nematic liquid crystal cells
International Nuclear Information System (INIS)
Zakharov, A.V.; Vakulenko, A.A.
2007-01-01
We have described a novel reorientation mechanism in the form of the traveling waves, under influence of an external electric field, directed parallel to both glass plates, which occur in the twisted nematic cell (TNC). It is found that the slowest velocity of the traveling front is proportional to the field strength, and, approximately, in three times higher than the front velocity corresponding to the non-traveling solution. The value of the critical electric field E cr which may excite the traveling waves in the TNC in π times less than the value of the threshold electric field E th corresponding to the untwisted geometry
Cerclage handling for improved fracture treatment. A biomechanical study on the twisting procedure.
Wähnert, D; Lenz, M; Schlegel, U; Perren, S; Windolf, M
2011-01-01
Twisting is clinically the most frequently applied method for tightening and maintaining cerclage fixation. The twisting procedure is controversially discussed. Several factors during twisting affect the mechanical behaviour of the cerclage. This in vitro study investigated the influence of different parameters of the twisting procedure on the fixation strength of the cerclage in an experimental setup with centripetal force application. Cortical half shells of the femoral shaft were mounted on a testing fixture. 1.0 mm, 1.25 mm and 1.5 mm stainless ste- el wire cerclages as well as a 1.0mm cable cerclage were applied to the bone. Pretension of the cerclage during the installation was measured during the locking procedure. Subsequently, cyclic testing was performed up to failure. Higher pretension could be achieved with increasing wire diameter. However, with larger wire diameter the drop of pre- tension due to the bending and cutting the twist also increased. The cable cerclage showed the highest pretension after locking. Cerclages twisted under traction revealed significantly higher initial cerclage tension. Plastically deformed twists offered higher cerclage pretension compared to twists which were deformed in the elastic region of the material. Cutting the wire within the twist caused the highest loss of cerclage tension (44% initial tension) whereas only 11 % was lost when cutting the wire ends separately. The bending direction of the twist significantly influenced the cerclage pretension. 45% pretension was lost in forward bending of the twist, 53% in perpendicular bending and 90% in backward bending. Several parameters affect the quality of a cerclage fixation. Adequate installation of cerclage wires could markedly improve the clinical outcome of cerclage.
The topological B model as a twisted spinning particle
International Nuclear Information System (INIS)
Marcus, Neil; Yankielowicz, Shimon
1994-01-01
The B-twisted topological sigma model coupled to topological gravity is supposed to be described by an ordinary field theory: a type of holomorphic Chern-Simons theory for the open string, and the Kodaira-Spencer theory for the closed string. We show that the B model can be represented as a particle theory, obtained by reducing the sigma model to one dimension, and replacing the coupling to topological gravity by a coupling to a twisted one-dimensional supergravity. The particle can be defined on any Kaehler manifold - it does not require the Calabi-Yau condition - so it may provide a more generalized setting for the B model than the topological sigma model.The one-loop partition function of the particle can be written in terms of the Ray-Singer torsion of the manifold, and agrees with that of the original B model. After showing how to deform the Kaehler and complex structures in the particle, we prove the independence of this partition function on the Kaehler structure, and investigate the origin of the holomorphic anomaly. To define other amplitudes, one needs to introduce interactions into the particle. The particle will then define a field theory, which may or may not be the Chern-Simons or Kodaira-Spencer theories. ((orig.))
Angular momentum transport with twisted exciton wave packets
Zang, Xiaoning; Lusk, Mark T.
2017-10-01
A chain of cofacial molecules with CN or CN h symmetry supports excitonic states with a screwlike structure. These can be quantified with the combination of an axial wave number and an azimuthal winding number. Combinations of these states can be used to construct excitonic wave packets that spiral down the chain with well-determined linear and angular momenta. These twisted exciton wave packets can be created and annihilated using laser pulses, and their angular momentum can be optically modified during transit. This allows for the creation of optoexcitonic circuits in which information, encoded in the angular momentum of light, is converted into excitonic wave packets that can be manipulated, transported, and then reemitted. A tight-binding paradigm is used to demonstrate the key ideas. The approach is then extended to quantify the evolution of twisted exciton wave packets in a many-body, multilevel time-domain density functional theory setting. In both settings, numerical methods are developed that allow the site-to-site transfer of angular momentum to be quantified.
Reconstruction of Twist Torque in Main Parachute Risers
Day, Joshua D.
2015-01-01
The reconstruction of twist torque in the Main Parachute Risers of the Capsule Parachute Assembly System (CPAS) has been successfully used to validate CPAS Model Memo conservative twist torque equations. Reconstruction of basic, one degree of freedom drop tests was used to create a functional process for the evaluation of more complex, rigid body simulation. The roll, pitch, and yaw of the body, the fly-out angles of the parachutes, and the relative location of the parachutes to the body are inputs to the torque simulation. The data collected by the Inertial Measurement Unit (IMU) was used to calculate the true torque. The simulation then used photogrammetric and IMU data as inputs into the Model Memo equations. The results were then compared to the true torque results to validate the Model Memo equations. The Model Memo parameters were based off of steel risers and the parameters will need to be re-evaluated for different materials. Photogrammetric data was found to be more accurate than the inertial data in accounting for the relative rotation between payload and cluster. The Model Memo equations were generally a good match and when not matching were generally conservative.
The dipole representation of vector meson electroproduction beyond leading twist
Energy Technology Data Exchange (ETDEWEB)
Besse, A. [LPT, Universite Paris-Sud, CNRS, 91405, Orsay (France); Szymanowski, L. [National Center for Nuclear Research (NCBJ), Warsaw (Poland); Wallon, S., E-mail: wallon@th.u-psud.fr [LPT, Universite Paris-Sud, CNRS, 91405, Orsay (France); UPMC Univ. Paris 06, Faculte de Physique, 4 place Jussieu, 75252 Paris Cedex 05 (France)
2013-02-01
We link the recent computation beyond leading twist of the impact factor of the transition {gamma}{sub T}{sup Low-Asterisk }{yields}{rho}{sub T} performed in the light-cone collinear approach, to the dipole picture by expressing the hard part of the process through its Fourier transform in coordinate space. We show that in the Wandzura-Wilczek approximation the impact factor up to twist 3 factorises in the wave function of the photon combined with the distribution amplitudes of the {rho}-meson and the colour dipole scattering amplitude with the t-channel gluons. We show also that beyond the Wandzura-Wilczek approximation, the hard contribution of the amplitude still exhibits the signature of the interaction of a single colour dipole with the t-channel gluons. This result allows a phenomenological approach of the helicity amplitudes of the leptoproduction of vector meson, by combining our results to a dipole/target scattering amplitude model.
Beams made of twisted atoms: A theoretical analysis
Energy Technology Data Exchange (ETDEWEB)
Hayrapetyan, Armen [Physikalisches Institut, Ruprecht-Karls-Universitaet Heidelberg, 69120 Heidelberg (Germany); Matula, Oliver [Physikalisches Institut, Ruprecht-Karls-Universitaet Heidelberg, 69120 Heidelberg (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Surzhykov, Andrey [Helmholtz-Institut Jena, 07743 Jena (Germany); Fritzsche, Stephan [Helmholtz-Institut Jena, 07743 Jena (Germany); Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, 07743 Jena (Germany)
2014-07-01
We have analyzed Bessel beams of two-level atoms that are driven by a linearly polarized laser light. Based on the Schroedinger equation for two-level systems, we first determine the states of two-level atoms in a plane-wave field by taking into account propagation directions both of the atom and the field. For such laser-driven two-level atoms, we construct Bessel beams by going beyond the typical paraxial approximation. In particular, we show that the probability density of these atomic beams exhibits a non-trivial, Bessel-squared-type behavior. The profile of such twisted atoms is affected by atom and laser parameters, such as the nuclear charge, atom velocity, laser frequency, and propagation geometry of the atom and laser beams. Moreover, we spatially and temporally characterize the beam of hydrogen and selected (neutral) alkali-metal atoms that carry non-zero orbital angular momentum (OAM). The proposed spatiotemporal Bessel states (i) are able to describe twisted states of any two-level system which is driven by the radiation field and (ii) have potential applications in atomic and nuclear processes as well as in quantum communication.
Dickens's Dichotomous Formula for Social Reform In Oliver Twist
Directory of Open Access Journals (Sweden)
Taher Badinjki
2016-11-01
Full Text Available Oliver Twist was a direct appeal to society to take action against poverty, exploitation of children, oppression of women, and was meant to be a picture of the "dregs of life” in all their deformity and wretchedness. Among the most miserable inhabitants of the world of Oliver Twist, Nancy appears as a key figure. Dickens was anxious to expose the truth about such a woman because he believed it would be a service to society. Dickens's portrayal of Nancy illustrates the power of the dual conception of womanhood held at the time. On the one hand, a woman might be conceived as someone refined and somewhat remote from ordinary life like Rose Maylie. On the other hand, there was a certain fascination in a woman's degradation, even though that could be shown only indirectly. Nancy is a demonstration of the two elements combined together. Dickens took the ideal nature of womanhood and the depravity of the prostitute, and combined them in a remarkable dramatization which he had some right to claim was also true to life. The book is an astounding rebuttal of contemporary prejudice, and a call for more humane and liberal attitudes. These attitudes are based on the concepts that there is now a radically different way of looking at human nature, that everything ought to depend on what one is in oneself, and that it is only in love that humans can live purposefully and happily with each other.
The ρ-meson longitudinal leading-twist distribution amplitude
Directory of Open Access Journals (Sweden)
Hai-Bing Fu
2014-11-01
Full Text Available In the present paper, we suggest a convenient model for the vector ρ-meson longitudinal leading-twist distribution amplitude ϕ2;ρ‖, whose distribution is controlled by a single parameter B2;ρ‖. By choosing proper chiral current in the correlator, we obtain new light-cone sum rules (LCSR for the B→ρ TFFs A1, A2 and V, in which the δ1-order ϕ2;ρ‖ provides dominant contributions. Then we make a detailed discussion on the ϕ2;ρ‖ properties via those B→ρ TFFs. A proper choice of B2;ρ‖ can make all the TFFs agree with the lattice QCD predictions. A prediction of |Vub| has also been presented by using the extrapolated TFFs, which indicates that a larger B2;ρ‖ leads to a larger |Vub|. To compare with the BABAR data on |Vub|, the longitudinal leading-twist DA ϕ2;ρ‖ prefers a doubly-humped behavior.
Maximally twisted mass lattice QCD at the physical pion mass
International Nuclear Information System (INIS)
Kostrzewa, Bartosz
2016-01-01
In computer simulations of Lattice Quantum Chromodynamics, the usage of unphysically large quark masses and the subsequent extrapolation of results to the physical value of the quark masses are major sources of systematic uncertainty. In this thesis, the feasibility and practicality of numerical simulations of Quantum Chromodynamics with physically light up and down quarks using the Wilson twisted mass quark discretisation are explored. Working in this regime is complicated firstly by the numerical expense of these simulations and secondly by the presence of potentially large lattice artefacts. The twisted mass discretisation is affected by an unphysical mass difference between the charged and neutral pions, rendering simulations at the physical charged pion mass infeasible if this mass splitting is too large. With the aim of reducing it, the Sheikholeslami-Wohlert term is added to the twisted mass fermion action and simulations with mass degenerate up and down quarks are then performed as a proof of concept. It is demonstrated that these simulations are stable and that the parameters of the lattice theory can be successfully tuned to correspond to the physical charged pion mass. Subsequently, the parameter tuning for simulations with mass degenerate up and down quarks as well as strange and charm quarks is explored and it is shown that it can be carried out in steps. As benchmark observables, the masses and decay constants of pseudoscalar mesons with light, strange and charm valence quarks are calculated and seen to largely reproduce their phenomenological values, even though continuum and infinite volume extrapolations are not performed. Light, strange and charm quark mass estimates are determined based on this data and also seen to coincide with phenomenological and other lattice determinations. In this analysis, a particular emphasis is placed on the systematic error due to the choice of fit range for pseudoscalar correlation functions and a weighting method is
Low-lying baryon spectrum with two dynamical twisted mass fermions
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Computation-based Science and Technology Research Center, Cyprus Institute, Nicosia (Cyprus); Baron, R.; Guichon, P. [CEA-Saclay, IRFU/Service de Physique Nucleaire, Gif-sur-Yvette (France); Carbonell, J.; Drach, V. [UJF/CNRS/IN2P3, Grenoble (France). Lab. de Physique Subatomique et Cosmologie; Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Korzec, T. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Pene, O. [Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique
2009-10-15
The masses of the low lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudo scalar masses in the range of about 270 MeV to 500 MeV. The strange valence quark mass is tuned to reproduce the mass of the kaon in the physical limit. The tree-level Symanzik improved gauge action is employed. We use lattices of spatial size 2.1 fm and 2.7 fm at two values of the lattice spacing with r{sub 0}/a=5.22(2) and r{sub 0}/a=6.61(3). We check for both finite volume and cut-off effects on the baryon masses. We performed a detailed study of the chiral extrapolation of the octet and decuplet masses using SU(2) {chi}PT. The lattice spacings determined using the nucleon mass at the physical point are consistent with the values extracted using the pion decay constant. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. The baryon masses that we find after taking the continuum limit and extrapolating to the physical limit are in good agreement with experiment. (orig.)
Sox5 induces epithelial to mesenchymal transition by transactivation of Twist1
International Nuclear Information System (INIS)
Pei, Xin-Hong; Lv, Xin-Quan; Li, Hui-Xiang
2014-01-01
Highlights: • Depletion of Sox5 inhibits breast cancer proliferation, migration, and invasion. • Sox5 transactivates Twist1 expression. • Sox5 induces epithelial to mesenchymal transition through transactivation of Twist1 expression. - Abstract: The epithelial to mesenchymal transition (EMT), a highly conserved cellular program, plays an important role in normal embryogenesis and cancer metastasis. Twist1, a master regulator of embryonic morphogenesis, is overexpressed in breast cancer and contributes to metastasis by promoting EMT. In exploring the mechanism underlying the increased Twist1 in breast cancer cells, we found that the transcription factor SRY (sex-determining region Y)-box 5(Sox5) is up-regulation in breast cancer cells and depletion of Sox5 inhibits breast cancer cell proliferation, migration, and invasion. Furthermore, depletion of Sox5 in breast cancer cells caused a dramatic decrease in Twist1 and chromosome immunoprecipitation assay showed that Sox5 can bind directly to the Twist1 promoter, suggesting that Sox5 transactivates Twist1 expression. We further demonstrated that knockdown of Sox5 up-regulated epithelial phenotype cell biomarker (E-cadherin) and down-regulated mesenchymal phenotype cell biomarkers (N-cadherin, Vimentin, and Fibronectin 1), resulting in suppression of EMT. Our study suggests that Sox5 transactivates Twist1 expression and plays an important role in the regulation of breast cancer progression
The geometrical origin of the strain-twist coupling in double helices
DEFF Research Database (Denmark)
Olsen, Kasper; Bohr, Jakob
2011-01-01
A simple geometrical explanation for the counterintuitive phenomenon when twist leads to extension in double helices is presented. The coupling between strain and twist is investigated using a tubular description. It is shown that the relation between strain and rotation is universal and depends...
Effect of Magnetic Twist on Nonlinear Transverse Kink Oscillations of Line-tied Magnetic Flux Tubes
Terradas, J.; Magyar, N.; Van Doorsselaere, T.
2018-01-01
Magnetic twist is thought to play an important role in many structures of the solar atmosphere. One of the effects of twist is to modify the properties of the eigenmodes of magnetic tubes. In the linear regime standing kink solutions are characterized by a change in polarization of the transverse displacement along the twisted tube. In the nonlinear regime, magnetic twist affects the development of shear instabilities that appear at the tube boundary when it is oscillating laterally. These Kelvin–Helmholtz instabilities (KHI) are produced either by the jump in the azimuthal component of the velocity at the edge of the sharp boundary between the internal and external part of the tube or by the continuous small length scales produced by phase mixing when there is a smooth inhomogeneous layer. In this work the effect of twist is consistently investigated by solving the time-dependent problem including the process of energy transfer to the inhomogeneous layer. It is found that twist always delays the appearance of the shear instability, but for tubes with thin inhomogeneous layers the effect is relatively small for moderate values of twist. On the contrary, for tubes with thick layers, the effect of twist is much stronger. This can have some important implications regarding observations of transverse kink modes and the KHI itself.
Light hadrons from Nf=2+1+1 dynamical twisted mass fermions
Baron, R.; Blossier, B.; Boucaud, P.; Carbonell, J.; Deuzeman, A.; Drach, V.; Farchioni, F.; Gimenez, V.; Herdoiza, G.; Jansen, K.; Michael, C.; Montvay, I.; Pallante, E.; Pène, O.; Reker, S.; Urbach, C.; Wagner, M.; Wenger, U.; Collaboration, for the ETM
2011-01-01
We present results of lattice QCD simulations with mass-degenerate up and down and mass-split strange and charm (Nf=2+1+1) dynamical quarks using Wilson twisted mass fermions at maximal twist. The tuning of the strange and charm quark masses is performed at three values of the lattice spacing a~0.06
First results of ETMC simulations with Nf=2+1+1 maximally twisted mass fermions
Baron, R.; Blossier, B.; Boucaud, P.; Deuzeman, A.; Drach, V.; Farchioni, F.; Gimenez, V.; Herdoiza, G.; Jansen, K.; Michael, C.; Montvay, I.; Palao, D.; Pallante, E.; Pène, O.; Reker, S.; Urbach, C.; Wagner, M.; Wenger, U.; Collaboration, for the ETM
2009-01-01
We present first results from runs performed with Nf=2+1+1 flavours of dynamical twisted mass fermions at maximal twist: a degenerate light doublet and a mass split heavy doublet. An overview of the input parameters and tuning status of our ensembles is given, together with a comparison with results
Vacuum fluctuations of twisted fields in the space time of cosmic strings
International Nuclear Information System (INIS)
Matsas, G.E.A.
1990-01-01
A twisted scalar field conformally coupled to gravitation is used to calculate the vacuum stress-energy tensor in the background spacetime generated by an infinite straight gauge cosmic string. The result has an absolute numerical value close to the one obtained with a non-twisted conformal scalar field but their signals are opposite. (author) [pt
Witte, van de P.; Neuteboom, E.E.; Brehmer, M.; Lub, Johan
1999-01-01
A method for the production of polarization sensitive recordings in liquid crystalline polymers is presented. The system is based on local modification of the twist angle of chiral nematic polymer films. The twist angle of the polymer film is varied by modifying the chemical structure of the chiral
Higher twist effects in QCD description of light meson exclusive formfactors
International Nuclear Information System (INIS)
Gorskij, A.S.
1987-01-01
The general approach to a quantitative description of higher twist effects in hard exclusive processes in QCD is proposed. The consistent calculations in coordinate space and the choice of special gauges for quantum and classical gluon fields are essential ingradients of this method. The self consistent system of twist three wave functions for π-meson has been built
DEFF Research Database (Denmark)
Nairismägi, Maarja-Liisa; Vislovukh, Andrii; Meng, Q
2012-01-01
and EMT, we found TWIST1 to be upregulated during EMT and downregulated early in carcinogenesis. The TWIST1 3′UTR contains putative regulatory elements, including miRNA target sites and two cytoplasmic polyadenylation elements (CPE). We found that miR-580, CPEB1, and CPEB2 act as negative regulators...
Comparison of split double and triple twists in pair figure skating.
King, Deborah L; Smith, Sarah L; Brown, Michele R; McCrory, Jean L; Munkasy, Barry A; Scheirman, Gary I
2008-05-01
In this study, we compared the kinematic variables of the split triple twist with those of the split double twist to help coaches and scientists understand these landmark pair skating skills. High-speed video was taken during the pair short and free programmes at the 2002 Salt Lake City Winter Olympics and the 2003 International Skating Union Grand Prix Finals. Three-dimensional analyses of 14 split double twists and 15 split triple twists from eleven pairs were completed. In spite of considerable variability in the performance variables among the pairs, the main difference between the split double twists and split triple twists was an increase in rotational rate. While eight of the eleven pairs relied primarily on an increased rotational rate to complete the split triple twist, three pairs employed a combined strategy of increased rotational rate and increased flight time due predominantly to delayed or lower catches. These results were similar to observations of jumps in singles skating for which the extra rotation is typically due to an increase in rotational velocity; increases in flight time come primarily from delayed landings as opposed to additional height during flight. Combining an increase in flight time and rotational rate may be a good strategy for completing the split triple twist in pair skating.
On the propagation and the twist of Gaussian light in first-order optical systems
Bastiaans, M.J.; Nijhawan, O.P.; Gupta, A.K.; Musla, A.K.; Singh, Kehar
1998-01-01
A measure for the twist of Gaussian light is expressed in terms of the second-order moments of the Wigner distribution function. The propagation law for these moments through first-order optical systems is used to express the twist in the output plane in terms of moments in the input plane, and vice
Modal Properties and Stability of Bend-Twist Coupled Wind Turbine Blades
DEFF Research Database (Denmark)
Stäblein, Alexander R.; Hansen, Morten Hartvig; Verelst, David Robert
2017-01-01
a steady-state equilibrium using the aero-servo-elastic tool HAWCStab2 which has been extended by a beam element that allows for fully coupled cross-sectional properties. Bend-twist coupling is introduced in the cross-sectional stiffness matrix by means of coupling coefficients that introduce twist...
Osserman and conformally Osserman manifolds with warped and twisted product structure
Brozos-Vazquez, M.; Garcia-Rio, E.; Vazquez-Lorenzo, R.
2008-01-01
We characterize Osserman and conformally Osserman Riemannian manifolds with the local structure of a warped product. By means of this approach we analyze the twisted product structure and obtain, as a consequence, that the only Osserman manifolds which can be written as a twisted product are those of constant curvature.
Directory of Open Access Journals (Sweden)
Yuji Koike
2016-08-01
Full Text Available We compute the contribution from the longitudinally polarized proton to the twist-3 double-spin asymmetry ALT in inclusive (light hadron production from proton–proton collisions, i.e., p↑p→→hX. We show that using the relevant QCD equation-of-motion relation and Lorentz invariance relation allows one to eliminate the twist-3 quark-gluon correlator (associated with the longitudinally polarized proton in favor of one-variable twist-3 quark distributions and the (twist-2 transversity parton density. Including this result with the twist-3 pieces associated with the transversely polarized proton and unpolarized final-state hadron (which have already been calculated in the literature, we now have the complete leading-order cross section for this process.
An improved hazard rate twisting approach for the statistic of the sum of subexponential variates
Rached, Nadhir B.; Kammoun, Abla; Alouini, Mohamed-Slim; Tempone, Raul
2015-01-01
In this letter, we present an improved hazard rate twisting technique for the estimation of the probability that a sum of independent but not necessarily identically distributed subexponential Random Variables (RVs) exceeds a given threshold. Instead of twisting all the components in the summation, we propose to twist only the RVs which have the biggest impact on the right-tail of the sum distribution and keep the other RVs unchanged. A minmax approach is performed to determine the optimal twisting parameter which leads to an asymptotic optimality criterion. Moreover, we show through some selected simulation results that our proposed approach results in a variance reduction compared to the technique where all the components are twisted.
Supersymmetric gauged double field theory: systematic derivation by virtue of twist
International Nuclear Information System (INIS)
Cho, Wonyoung; Fernández-Melgarejo, J.J.; Jeon, Imtak; Park, Jeong-Hyuck
2015-01-01
In a completely systematic and geometric way, we derive maximal and half-maximal supersymmetric gauged double field theories in lower than ten dimensions. To this end, we apply a simple twisting ansatz to the D=10 ungauged maximal and half-maximal supersymmetric double field theories constructed previously within the so-called semi-covariant formalism. The twisting ansatz may not satisfy the section condition. Nonetheless, all the features of the semi-covariant formalism, including its complete covariantizability, are still valid after the twist under alternative consistency conditions. The twist allows gaugings as supersymmetry preserving deformations of the D=10 untwisted theories after Scherk-Schwarz-type dimensional reductions. The maximal supersymmetric twist requires an extra condition to ensure both the Ramond-Ramond gauge symmetry and the 32 supersymmetries unbroken.
The geometrical origin of the strain-twist coupling in double helices
Directory of Open Access Journals (Sweden)
Kasper Olsen
2011-03-01
Full Text Available A simple geometrical explanation for the counterintuitive phenomenon when twist leads to extension in double helices is presented. The coupling between strain and twist is investigated using a tubular description. It is shown that the relation between strain and rotation is universal and depends only on the pitch angle. For pitch angles below 39.4° strain leads to further winding, while for larger pitch angles strain leads to unwinding. The zero-twist structure, with a pitch angle of 39.4°, is at the unique point between winding and unwinding and independent of the mechanical properties of the double helix. The existence of zero-twist structures, i.e. structures that display neither winding, nor unwinding under strain is discussed. Close-packed double helices are shown to extend rather than shorten when twisted. Numerical estimates of this elongation upon winding are given for DNA, chromatin, and RNA.
Gauging the twisted Poincare symmetry as a noncommutative theory of gravitation
International Nuclear Information System (INIS)
Chaichian, M.; Tureanu, A.; Oksanen, M.; Zet, G.
2009-01-01
Einstein's theory of general relativity was formulated as a gauge theory of Lorentz symmetry by Utiyama in 1956, while the Einstein-Cartan gravitational theory was formulated by Kibble in 1961 as the gauge theory of Poincare transformations. In this framework, we propose a formulation of the gravitational theory on canonical noncommutative space-time by covariantly gauging the twisted Poincare symmetry, in order to fulfil the requirement of covariance under the general coordinate transformations, an essential ingredient of the theory of general relativity. It appears that the twisted Poincare symmetry cannot be gauged by generalizing the Abelian twist to a covariant non-Abelian twist, nor by introducing a more general covariant twist element. The advantages of such a formulation as well as the related problems are discussed and possible ways out are outlined.
International Nuclear Information System (INIS)
Anikin, I.V.; Ivanov, D.Yu.; Pire, B.; Szymanowski, L.; Wallon, S.
2010-01-01
We describe a consistent approach to factorization of scattering amplitudes for exclusive processes beyond the leading twist approximation. The method involves the Taylor expansion of the scattering amplitude in the momentum space around the dominant light-cone direction and thus naturally introduces an appropriate set of non-perturbative correlators which encode effects not only of the lowest but also of the higher Fock states of the produced particle. The reduction of original set of correlators to a set of independent ones is achieved with the help of equations of motion and invariance of the scattering amplitude under rotation on the light cone. We compare the proposed method with the covariant method formulated in the coordinate space, based on the operator product expansion. We prove the equivalence of two proposed parametrizations of the ρ T distribution amplitudes. As a concrete application, we compute the expressions of the impact factor for the transition of virtual photon to transversally polarised ρ-meson up to the twist 3 accuracy within these two quite different methods and show that they are identical.
Thathia, Shabnam H.; Ferguson, Stuart; Gautrey, Hannah E.; van Otterdijk, Sanne D.; Hili, Michela; Rand, Vikki; Moorman, Anthony V.; Meyer, Stefan; Brown, Robert; Strathdee, Gordon
2012-01-01
Background Altered regulation of many transcription factors has been shown to be important in the development of leukemia. TWIST2 modulates the activity of a number of important transcription factors and is known to be a regulator of hematopoietic differentiation. Here, we investigated the significance of epigenetic regulation of TWIST2 in the control of cell growth and survival and in response to cytotoxic agents in acute lymphoblastic leukemia. Design and Methods TWIST2 promoter methylation status was assessed quantitatively, by combined bisulfite and restriction analysis (COBRA) and pyrosequencing assays, in multiple types of leukemia and TWIST2 expression was determined by quantitative reverse transcriptase polymerase chain reaction analysis. The functional role of TWIST2 in cell proliferation, survival and response to chemotherapy was assessed in transient and stable expression systems. Results We found that TWIST2 was inactivated in more than 50% of cases of childhood and adult acute lymphoblastic leukemia through promoter hypermethylation and that this epigenetic regulation was especially prevalent in RUNX1-ETV6-driven cases. Re-expression of TWIST2 in cell lines resulted in a dramatic reduction in cell growth and induction of apoptosis in the Reh cell line. Furthermore, re-expression of TWIST2 resulted in increased sensitivity to the chemotherapeutic agents etoposide, daunorubicin and dexamethasone and TWIST2 hypermethylation was almost invariably found in relapsed adult acute lymphoblastic leukemia (91% of samples hypermethylated). Conclusions This study suggests a dual role for epigenetic inactivation of TWIST2 in acute lymphoblastic leukemia, initially through altering cell growth and survival properties and subsequently by increasing resistance to chemotherapy. PMID:22058208
Optical yarn assessment system for twist measurement in rotor-spun yarn
International Nuclear Information System (INIS)
Jhatial, R.A.
2015-01-01
This paper presents the development of an optical yarn assessment system for evaluation of twist and structure of twisted yarn. The system comprises a yarn carriage unit, a video microscope and a personal computer. This system was used in conjunction with the well-known tracer fibre technique. This system enables digital images to be grabbed and continuous movies of the yarn to be recorded in order to facilitate the measurement of twist and the analysis of yarn structure. Yarn samples from polyester, viscose and cotton with 35 tex and 485 turns/meter were spun from the roving with 2.3% of black fibres on the SKF laboratory ring frame. In order to measure the twist in the rotor yarns with the optical yarn assessment system, a set of yarn samples from same fibres were spun on RU 14 rotor machine with 35 tex and 475 turns/meter. The twist was measured with the optical yarn assessment system and sixty tests of each sample were carried out on the Zweigle D301. It is clear from the results that there is consistency in the twist of ring-spun yarn measured by the optical yarn assessment system. However, the measured twist with the Zwiegle D301 is inconsistent in the different yarns. The difference in the mean twist measured with the optical twist measuring system and the double untwist-twist method was not significant at a 5% probability level when data was analyzed with t test by using SPSS (Statistical Package for Social Sciences). (author)
Twist-1 Up-Regulation in Carcinoma Correlates to Poor Survival
Directory of Open Access Journals (Sweden)
Alimujiang Wushou
2014-11-01
Full Text Available Epithelial-to-mesenchymal transition (EMT facilitates tumor metastasis. Twist is a basic helix-loop-helix protein that modulates many target genes through E-box-responsive elements. There are two twist-like proteins, Twist-1 and Twist-2, sharing high structural homology in mammals. Twist-1 was found to be a key factor in the promotion of metastasis of cancer cells, and is known to induce EMT. Twist-1 participation in carcinoma progression and metastasis has been reported in a variety of tumors. However, controversy exists concerning the correlation between Twist-1 and prognostic value with respect to carcinoma. A systematic review and meta-analysis were performed to determine whether the expression of Twist-1 was associated with the prognosis of carcinoma patients. This analysis included 17 studies: four studies evaluated lung cancer, three evaluated head and neck cancer, two evaluated breast cancer, two evaluated esophageal cancer, two evaluated liver cancer and one each evaluated osteosarcoma, bladder, cervical and ovarian cancer. A total of 2006 patients were enrolled in these studies, and the median trial sample size was 118 patients. Twist-1 expression was associated with worse overall survival (OS at both 3 years (hazard ratio “HR” for death = 2.13, 95% CI = 1.86 to 2.45, p < 0.001 and 5 years (HR for death = 2.01, 95% CI = 1.76 to 2.29, p < 0.001. Expression of Twist-1 is associated with worse survival in carcinoma.
Existence and equivalence of twisted products on a symplectic manifold
International Nuclear Information System (INIS)
Lichnerowicz, A.
1979-01-01
The twisted products play an important role in Quantum Mechanics. A distinction is introduced between Vey *sub(γ) products and strong Vey *sub(γ) products and it is proved that each *sub(γ) product is equivalent to a Vey *sub(γ) product. If b 3 (W) = 0, the symplectic manifold (W,F) admits strong Vey *sub(Gn) products. If b 2 (W) = 0, all *sub(γ) products are equivalent as well as the Vey Lie algebras. In the general case the formal Lie algebras are characterized which are generated by a *sub(γ) product and it proved that the existance of a *sub(γ)-product is equivalent to the existance of a formal Lie algebra infinitesimally equivalent to a Vey Lie algebra at the first order. (Auth.)
The self-field effect in twisted superconducting composites
International Nuclear Information System (INIS)
Duchateau, J.L.; Turck, B.; Krempasky, L.; Polak, M.
1976-01-01
Since twisting of composites does not cause a transposition with respect to the self-field of the transport current, they behave like a bulk superconductor with averaged critical current density, when the transport current is changed. Consequently, the electric field is given by the history of the transport current changes. Using a simplified model (Jsub(c) = const) the expressions for the electric fields and losses for the first and immediately following second increase of the transport current are derived. Experimental results are also presented which clearly show higher electric field during the first run than during the following, which agrees with theoretical predictions. Quite a good quantitative agreement between theory and experiment was obtained up to about 80 % of the critical transport current. The influence of the copper matrix is also discussed. (author)
Accelerating Twisted Mass LQCD with QPhiX
Energy Technology Data Exchange (ETDEWEB)
Schröck, Mario [INFN, Rome3; Simula, Silvano [INFN, Rome3; Strelchenko, Alexei [Fermilab
2016-07-08
We present the implementation of twisted mass fermion operators for the QPhiX library. We analyze the performance on the Intel Xeon Phi (Knights Corner) coprocessor as well as on Intel Xeon Haswell CPUs. In particular, we demonstrate that on the Xeon Phi 7120P the Dslash kernel is able to reach 80\\% of the theoretical peak bandwidth, while on a Xeon Haswell E5-2630 CPU our generated code for the Dslash operator with AVX2 instructions outperforms the corresponding implementation in the tmLQCD library by a factor of $\\sim 5\\times$ in single precision. We strong scale the code up to 6.8 (14.1) Tflops in single (half) precision on 64 Xeon Haswell CPUs.
Threshold corrections and gauge symmetry in twisted superstring models
International Nuclear Information System (INIS)
Pierce, D.M.
1994-01-01
Threshold corrections to the running of gauge couplings are calculated for superstring models with free complex world sheet fermions. For two N=1 SU(2)xU(1) 5 models, the threshold corrections lead to a small increase in the unification scale. Examples are given to illustrate how a given particle spectrum can be described by models with different boundary conditions on the internal fermions. We also discuss how complex twisted fermions can enhance the symmetry group of an N=4, SU(3)xU(1)xU(1) model to the gauge group SU(3)xSU(2)xU(1). It is then shown how a mixing angle analogous to the Weinberg angle depends on the boundary conditions of the internal fermions
DNA origami-based nanoribbons: assembly, length distribution, and twist
Energy Technology Data Exchange (ETDEWEB)
Jungmann, Ralf; Scheible, Max; Kuzyk, Anton; Pardatscher, Guenther; Simmel, Friedrich C [Lehrstuhl fuer Bioelektronik, Physik-Department and ZNN/WSI, Technische Universitaet Muenchen, Am Coulombwall 4a, 85748 Garching (Germany); Castro, Carlos E, E-mail: simmel@ph.tum.de [Labor fuer Biomolekulare Nanotechnologie, Physik-Department and ZNN/WSI, Technische Universitaet Muenchen, Am Coulombwall 4a, 85748 Garching (Germany)
2011-07-08
A variety of polymerization methods for the assembly of elongated nanoribbons from rectangular DNA origami structures are investigated. The most efficient method utilizes single-stranded DNA oligonucleotides to bridge an intermolecular scaffold seam between origami monomers. This approach allows the fabrication of origami ribbons with lengths of several micrometers, which can be used for long-range ordered arrangement of proteins. It is quantitatively shown that the length distribution of origami ribbons obtained with this technique follows the theoretical prediction for a simple linear polymerization reaction. The design of flat single layer origami structures with constant crossover spacing inevitably results in local underwinding of the DNA helix, which leads to a global twist of the origami structures that also translates to the nanoribbons.
DNA origami-based nanoribbons: assembly, length distribution, and twist
International Nuclear Information System (INIS)
Jungmann, Ralf; Scheible, Max; Kuzyk, Anton; Pardatscher, Guenther; Simmel, Friedrich C; Castro, Carlos E
2011-01-01
A variety of polymerization methods for the assembly of elongated nanoribbons from rectangular DNA origami structures are investigated. The most efficient method utilizes single-stranded DNA oligonucleotides to bridge an intermolecular scaffold seam between origami monomers. This approach allows the fabrication of origami ribbons with lengths of several micrometers, which can be used for long-range ordered arrangement of proteins. It is quantitatively shown that the length distribution of origami ribbons obtained with this technique follows the theoretical prediction for a simple linear polymerization reaction. The design of flat single layer origami structures with constant crossover spacing inevitably results in local underwinding of the DNA helix, which leads to a global twist of the origami structures that also translates to the nanoribbons.
Twisted quantum double model of topological order with boundaries
Bullivant, Alex; Hu, Yuting; Wan, Yidun
2017-10-01
We generalize the twisted quantum double model of topological orders in two dimensions to the case with boundaries by systematically constructing the boundary Hamiltonians. Given the bulk Hamiltonian defined by a gauge group G and a 3-cocycle in the third cohomology group of G over U (1 ) , a boundary Hamiltonian can be defined by a subgroup K of G and a 2-cochain in the second cochain group of K over U (1 ) . The consistency between the bulk and boundary Hamiltonians is dictated by what we call the Frobenius condition that constrains the 2-cochain given the 3-cocyle. We offer a closed-form formula computing the ground-state degeneracy of the model on a cylinder in terms of the input data only, which can be naturally generalized to surfaces with more boundaries. We also explicitly write down the ground-state wave function of the model on a disk also in terms of the input data only.
New findings of twisted-wing parasites (Strepsiptera) in Alaska
Mcdermott, Molly
2016-01-01
Strepsipterans are a group of insects with a gruesome life history and an enigmatic evolutionary past. Called ‘twisted-wing parasites’, they are minute parasitoids with a very distinct morphology (Figure 1). Alternatively thought to be related to ichneumon wasps, Diptera (flies), Coleoptera (beetles), and even Neuroptera (net-winged insects) (Pohl and Beutel, 2013); the latest genetic and morphological data support the sister order relationship of Strepsiptera and Coleoptera (Niehuis et al., 2012). Strepsipterans are highly modified, males having two hind wings and halteres instead of front wings or elytra. Unlike most parasitoids, they develop inside active, living insects who are sexually sterilized but not killed until or after emergence (Kathirithamby et al., 2015).
Topological susceptibility from the twisted mass Dirac operator spectrum
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Collaboration: European Twisted Mass Collaboration
2013-12-15
We present results of our computation of the topological susceptibility with N{sub f}=2 and N{sub f}= +1+1 flavours of maximally twisted mass fermions, using the method of spectral projectors. We perform a detailed study of the quark mass dependence and discretization effects. We make an attempt to confront our data with chiral perturbation theory and extract the chiral condensate from the quark mass dependence of the topological susceptibility. We compare the value with the results of our direct computation from the slope of the mode number. We emphasize the role of autocorrelations and the necessity of long Monte Carlo runs to obtain results with good precision. We also show our results for the spectral projector computation of the ratio of renormalization constants Z{sub P}/Z{sub S}.
Localized topological states in Bragg multihelicoidal fibers with twist defects
Alexeyev, C. N.; Lapin, B. P.; Milione, G.; Yavorsky, M. A.
2016-06-01
We have studied the influence of a twist defect in multihelicoidal Bragg fibers on the emerging of localized defect modes. We have shown that if such a fiber is excited with a Gaussian beam this leads to the appearance of a defect-localized topological state, whose topological charge coincides with the order of rotational symmetry of the fiber's refractive index. We have shown that this effect has a pronounced crossover behavior. We have also formulated a principle of creating the systems that can nestle defect-localized topologically charged modes. According to this principle, such systems have to possess topological activity, that is, the ability to change the topological charge of the incoming field, and operate in the Bragg regime.
Topological susceptibility from the twisted mass Dirac operator spectrum
International Nuclear Information System (INIS)
Cichy, Krzysztof; Jansen, Karl; Cyprus Univ., Nicosia
2013-12-01
We present results of our computation of the topological susceptibility with N f =2 and N f = +1+1 flavours of maximally twisted mass fermions, using the method of spectral projectors. We perform a detailed study of the quark mass dependence and discretization effects. We make an attempt to confront our data with chiral perturbation theory and extract the chiral condensate from the quark mass dependence of the topological susceptibility. We compare the value with the results of our direct computation from the slope of the mode number. We emphasize the role of autocorrelations and the necessity of long Monte Carlo runs to obtain results with good precision. We also show our results for the spectral projector computation of the ratio of renormalization constants Z P /Z S .
Strong-field ionization with twisted laser pulses
Paufler, Willi; Böning, Birger; Fritzsche, Stephan
2018-04-01
We apply quantum trajectory Monte Carlo computations in order to model strong-field ionization of atoms by twisted Bessel pulses and calculate photoelectron momentum distributions (PEMD). Since Bessel beams can be considered as an infinite superposition of circularly polarized plane waves with the same helicity, whose wave vectors lie on a cone, we compared the PEMD of such Bessel pulses to those of a circularly polarized pulse. We focus on the momentum distributions in propagation direction of the pulse and show how these momentum distributions are affected by experimental accessible parameters, such as the opening angle of the beam or the impact parameter of the atom with regard to the beam axis. In particular, we show that we can find higher momenta of the photoelectrons, if the opening angle is increased.
On the difficulty of computing higher-twist corrections
International Nuclear Information System (INIS)
Martinelli, G.; Sachrajda, C.T.
1996-01-01
We discuss the evaluation of power corrections to hard scattering and decay processes for which an operator product expansion is applicable. The Wilson coefficient of the leading-twist operator is the difference of two perturbative series, each of which has a renormalon ambiguity of the same order as the power corrections themselves, but which cancel in the difference. We stress the necessity of calculating this coefficient function to sufficiently high orders in perturbation theory so as to make the uncertainty of the same order of or smaller than the relevant power corrections. We investigate in some simple examples whether this can be achieved. Our conclusion is that in most of the theoretical calculations which include power corrections, the uncertainties are at least comparable to the power corrections themselves, and that it will be a very difficult task to improve the situation. (orig.)
Nanofibrous Smart Fabrics from Twisted Yarns of Electrospun Piezopolymer.
Yang, Enlong; Xu, Zhe; Chur, Lucas K; Behroozfar, Ali; Baniasadi, Mahmoud; Moreno, Salvador; Huang, Jiacheng; Gilligan, Jules; Minary-Jolandan, Majid
2017-07-19
Smart textiles are envisioned to make a paradigm shift in wearable technologies to directly impart functionality into the fibers rather than integrating sensors and electronics onto conformal substrates or skin in wearable devices. Among smart materials, piezoelectric fabrics have not been widely reported, yet. Piezoelectric smart fabrics can be used for mechanical energy harvesting, for thermal energy harvesting through the pyroelectric effect, for ferroelectric applications, as pressure and force sensors, for motion detection, and for ultrasonic sensing. We report on mechanical and material properties of the plied nanofibrous piezoelectric yarns as a function of postprocessing conditions including thermal annealing and drawing (stretching). In addition, we used a continuous electrospinning setup to directly produce P(VDF-TrFE) nanofibers and convert them into twisted plied yarns, and demonstrated application of these plied yarns in woven piezoelectric fabrics. The results of this work can be an early step toward realization of piezoelectric smart fabrics.
Flicker in a twisted nematic spatial light modulator
Calderón-Hermosillo, Yuliana; García-Márquez, Jorge; Espinosa-Luna, Rafael; Ochoa, Noé Alcalá; López, Víctor; Aguilar, Alberto; Noé-Arias, Enrique; Alayli, Yasser
2013-06-01
Liquid Crystal on Silicon (LCoS) Spatial Light Modulators (SLM) are widely used for their capability to control beams howbeit fluctuations in phase and amplitude. It is then necessary to understand the negative effects of these fluctuations, also known as flicker, and the means to mitigate them. The flicker is observed either as high frequency variations of polarization, attenuation or high phase fluctuations on the wave front modulated by the LCoS device. Here, we compare the flicker behavior in a twisted nematic (TN) LCoS-SLM for different polarization schemes and temperatures. The quantitative evaluation shows that flicker is effectively reduced only by chilling the LCoS panel to temperatures just below 0 °C but, the LCoS modulation capability is also affected.
Nonlinear and hysteretic twisting effects in ocean cable laying
International Nuclear Information System (INIS)
Shashaty, A.J.
1983-01-01
Armored ocean cable unlays under the action of installation tensions and restraining moments applied by the ocean bottom and the ship's bow sheave. The process of elongation and twist is nonlinear and hysteretic. This process has often been assumed linear and reversible. The equations describing the moment which is developed in laying cable on the ocean bottom are worked out, without assuming linearity and reversibility. These equations are applied to some cases likely to arise. For a typical armored coaxial cable laid in 3700m (2,000 fathoms) depth without bottom tension, a steady-state laying-up moment of 134Nm (99 lbs. ft.) is developed. For the reversible case, no moment is developed. If the bottom tension is increased from zero to 33,375N (7500 lbs.) and then returned to zero, a peak moment of 198Nm (146 lbs. ft.) is developed
Fatigue Behaviors of Materials Processed by Planar Twist Extrusion
Ebrahimi, Mahmoud
2017-12-01
Since the last decade, the fabrication of ultrafine grain and nanostructure metals and alloys has attracted much attention in the field of materials engineering. The present study aimed at experimentally investigating the fatigue properties that are of great importance in dynamic structures before and after the planar twist extrusion process for both commercially pure copper and 6061 aluminum alloy. The results indicated that the yield strength, tensile strength, hardness, and fatigue endurance of copper increased by about 398, 122, 198, and 183 pct, respectively, while they improved by about 429, 212, 227, and 148 pct, respectively, in aluminum alloy as compared to the initial conditions. The stress-strain curves displayed sizable reduction of strain hardening. Furthermore, grain-size correction factors based on the empirical results were introduced to include the effect of the grain-size effect on both low and high-cycle fatigue strengths of the material.
Study of Implosion of Twisted Nested Arrays at the Angara-5-1 Facility
Mitrofanov, K. N.; Zukakishvili, G. G.; Aleksandrov, V. V.; Grabovski, E. V.; Frolov, I. N.; Gribov, A. N.
2018-01-01
Results are presented from experimental studies of the implosion of twisted nested arrays in which the wires of the outer and inner arrays are twisted about the array axis in opposite directions (clockwise and counterclockwise). Experiments with twisted arrays were carried out at the Angara-5-1 facility at currents of up to 4 MA. The currents through the arrays were switched either simultaneously or the current pulse through the outer array was delayed by 10-15 ns with the help of an anode spark gap. It is shown that, in such arrays, the currents flow along the inclined wires and, accordingly, there are both the azimuthal and axial components of the discharge current. The process of plasma implosion in twisted arrays depends substantially on the value of the axial (longitudinal) magnetic field generated inside the array by the azimuthal currents. Two-dimensional simulations of the magnetic field in twisted nested arrays were performed in the ( r, z) geometry with allowance for the skin effect in the discharge electrodes. It is shown that, depending on the geometry of the discharge electrodes, different configurations of the magnetic field can be implemented inside twisted nested arrays. The calculated magnetic configurations are compared with the results of measurements of the magnetic field inside such arrays. It is shown that the configuration of the axial magnetic field inside a twisted nested array depends substantially on the distribution of the azimuthal currents between the inner and outer arrays.
International Nuclear Information System (INIS)
Jouppila-Mättö, Anna; Närkiö-Mäkelä, Mervi; Soini, Ylermi; Pukkila, Matti; Sironen, Reijo; Tuhkanen, Hanna; Mannermaa, Arto; Kosma, Veli-Matti
2011-01-01
Epithelial-mesenchymal transition (EMT) is a crucial process in tumorigenesis since tumor cells attain fibroblast-like features enabling them to invade to surrounding tissue. Two transcription factors, TWIST and SNAI1, are fundamental in regulating EMT. Immunohistochemistry was used to study the expression of TWIST and SNAI1 in 109 pharyngeal squamous cell carcinomas. Tumors with intense stromal staining of TWIST relapsed more frequently (p = 0.04). Tumors with both positive TWIST and SNAI1 immunoreactivity in the stroma were at least Stage II (p = 0.05) and located more often in hypopharynx (p = 0.035). Tumors with negative immunostaining of TWIST and SNAI1 in the stromal compartment were smaller (T1-2) (p = 0.008), less advanced (SI-II) (p = 0.031) and located more often in the oropharynx (p = 0.007). Patients with negative SNAI1 and TWIST immunostaining in tumor stroma had a better 5-year disease-specific and overall survival (p = 0.037 and p = 0.014 respectively). TWIST and SNAI1 expression in stromal cells is associated with clinical and histopathological characteristics that indicate progressive disease. Negative expression of these EMT-promoting transcription factors predicts a better outcome
Higher-twist effects in the B → π transition form factor from QCD light-cone sum rules
Energy Technology Data Exchange (ETDEWEB)
Khodjamirian, Alexander; Rusov, Aleksey [Universitaet Siegen (Germany). Fakultaet IV, Department Physik, Theoretische Physik 1 Walter-Flex-Strasse 3 57068 Siegen
2016-07-01
I report on the progress in calculating new higher-twist corrections to the QCD light-cone sum rule for the B → π transition form factor. First, the expansion of the massive heavy-quark propagator in the external gluonic field near the light-cone was extended to include new terms containing the gluon-field strength derivatives. The resulting analytical expressions for the twist-5 and twist-6 contributions to the correlation function were obtained in a factorized approximation, expressed via the product of the quark-condensate density and the lower-twist pion distribution amplitudes. The numerical analysis of new higher-twist effects is in progress.
Directory of Open Access Journals (Sweden)
Karine Pallier
Full Text Available Metastasis is a multistep process and the main cause of mortality in lung cancer patients. We previously showed that EGFR mutations were associated with a copy number gain at a locus encompassing the TWIST1 gene on chromosome 7. TWIST1 is a highly conserved developmental gene involved in embryogenesis that may be reactivated in cancers promoting both malignant conversion and cancer progression through an epithelial to mesenchymal transition (EMT. The aim of this study was to investigate the possible implication of TWIST1 reactivation on the acquisition of a mesenchymal phenotype in EGFR mutated lung cancer. We studied a series of consecutive lung adenocarcinoma from Caucasian non-smokers for which surgical frozen samples were available (n = 33 and showed that TWIST1 expression was linked to EGFR mutations (P<0.001, to low CDH1 expression (P<0.05 and low disease free survival (P = 0.044. To validate that TWIST1 is a driver of EMT in EGFR mutated lung cancer, we used five human lung cancer cell lines and demonstrated that EMT and the associated cell mobility were dependent upon TWIST1 expression in cells with EGFR mutation. Moreover a decrease of EGFR pathway stimulation through EGF retrieval or an inhibition of TWIST1 expression by small RNA technology reversed the phenomenon. Collectively, our in vivo and in vitro findings support that TWIST1 collaborates with the EGF pathway in promoting EMT in EGFR mutated lung adenocarcinoma and that large series of EGFR mutated lung cancer patients are needed to further define the prognostic role of TWIST1 reactivation in this subgroup.
Correlation Between Expression of Twist and Podoplanin in Ductal Breast Carcinoma.
Grzegrzolka, Jedrzej; Wojtyra, Patrycja; Biala, Martyna; Piotrowska, Aleksandra; Gomulkiewicz, Agnieszka; Rys, Janusz; Podhorska-Okolow, Marzenna; Dziegiel, Piotr
2017-10-01
As a result of activation of transcription factors engaged in epithelial-mesenchymal transition (EMT), such as Twist, inhibition of epithelial markers and an increased expression of mesenchymal markers are observed. One of the specific markers of cancer-associated fibroblasts is podoplanin (PDPN) - a mucin-type membrane glycoprotein. The aim of this work was to study the localisation and intensity of expression of Twist and PDPN on the mRNA and protein level in cases of invasive ductal breast carcinoma (IDC), and its association with patients' clinico-pathological data. The study included archival material in a form of 80 paraffin IDC blocks and 11 IDC fragments frozen in liquid nitrogen. Immunohistochemical expression of Twist and PDPN was evaluated using light microscope and semiquantitative scale for evaluation of nuclear expression or immunoreactive scale (IRS) for evaluation of cytoplasmic expression. Material was isolated from frozen IDC fragments using laser micro-dissection (from cancer and stromal cells, separately) and was used to perform real-time PCR. Twist expression was higher in stromal cells in comparison to cancer cells. Analysis of patients' survival rate showed, that higher expression of Twist in cancer cells was associated with shorter overall survival time and shorter event-free survival time. The expression of PDPN was also higher in stromal cells in comparison with cancer cells. In addition, positive correlation was observed between expression of Twist and PDPN in stromal cells of IDC (r=0.267; p<0.05). The relationship between the higher expression of Twist in both cancer and stromal cells and shorter patients' survival indicates Twist as a potential useful prognostic marker in IDC. Positive correlation of Twist and PDPN expression may indicate the role of PDPN in EMT in IDC. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
Koška, Pavel; Peterka, Pavel; Doya, Valérie; Aubrecht, Jan; Kasik, Ivan; Podrazký, Ondřej
2017-05-01
High-power operation of fiber lasers was enabled by the invention of cladding-pumping in a double-clad fiber structure. Because of existence of so called skew rays in the inner clad of the fiber, pump absorption saturates along the fiber and pumping becomes inefficient. First studies of pump absorption efficiency enhancement were focused on fibers with broken circular symmetry of inner cladding eliminating skew rays [1,2]. Later, techniques of unconventional fiber coiling were proposed [3]. However, theoretical studies were limited to the assumption of a straight fiber. Even recently, the rigorous model accounting for fiber bending and twisting was described [4-6]. It was found that bending of the fiber influences modal spectra of the pump radiation and twisting provides quite efficient mode-scrambling. These effects in a synergic manner significantly enhances pump absorption rate in double clad fibers and improves laser system efficiency. In our contribution we review results of numerical modelling of pump absorption in various types of double-clad fibers, e.g., with cross section shape of hexagon, stadium, and circle; two-fiber bundle (so-called GTWave fiber structure) a panda fibers are also analyzed. We investigate pump field modal spectra evolution in hexagonally shaped fiber in straight, bended, and simultaneously bended and twisted fiber which brings new quality to understanding of the mode-scrambling and pump absorption enhancement. Finally, we evaluate the impact of enhanced pump absorption on signal gain in the fiber. These results can have practical impact in construction of fiber lasers: with pump absorption efficiency optimized by our new model (the other models did not take into account fiber twist), the double-clad fiber of shorter length can be used in the fiber lasers and amplifiers. In such a way the harmful influence of background losses and nonlinear effects can be minimized. [1] Doya, V., Legrand, O., Mortessagne, F., "Optimized absorption in a
Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review †
Budinski, Vedran; Donlagic, Denis
2017-01-01
Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation. PMID:28241510
Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review
Directory of Open Access Journals (Sweden)
Vedran Budinski
2017-02-01
Full Text Available Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.Invited Paper
Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review.
Budinski, Vedran; Donlagic, Denis
2017-02-23
Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.Invited Paper.
On the twists of interplanetary magnetic flux ropes observed at 1 AU
Wang, Yuming; Zhuang, Bin; Hu, Qiang; Liu, Rui; Shen, Chenglong; Chi, Yutian
2016-01-01
Magnetic flux ropes (MFRs) are one kind of fundamental structures in the solar physics, and involved in various eruption phenomena. Twist, characterizing how the magnetic field lines wind around a main axis, is an intrinsic property of MFRs, closely related to the magnetic free energy and stableness. So far it is unclear how much amount of twist is carried by MFRs in the solar atmosphere and in heliosphere and what role the twist played in the eruptions of MFRs. Contrasting to the solar MFRs,...
The electric dipole moment of the neutron from Nf=2+1+1 twisted mass fermions
International Nuclear Information System (INIS)
Alexandrou, C.; Athenodorou, A.; Constantinou, M.; Cyprus Institute, Nicosia; Hadjiyiannakou, K.; Cyprus Institute, Nicosia; George Washington Univ., Washington, DC; Jansen, K.; Koutsou, G.; Ottnad, K.; Bonn Univ.; Petschlies, M.; Bonn Univ.
2015-11-01
We extract the neutron electric dipole moment (nEDM) vertical stroke vector d n vertical stroke on configurations produced with N f =2+1+1 twisted mass fermions with lattice spacing of a ≅0.082 fm and a light quark mass that corresponds to M π ≅ 373 MeV. We do so by evaluating the CP-odd form factor F 3 for small values of the CP-violation parameter θ in the limit of zero momentum transfer. This limit is extracted using the usual parametrization but in addition position space methods. The topological charge is computed via cooling and gradient flow using the Wilson, Symanzik tree-level improved and Iwasaki actions for smoothing. We obtain consistent results for all choices of smoothing procedures and methods to extract F 3 at zero momentum transfer. For the ensemble analyzed we find a value of nEDM of vertical stroke vector d n vertical stroke /θ=0.045(6)(1) e.fm.
Directory of Open Access Journals (Sweden)
Kumburegama Shalika
2011-01-01
Full Text Available Abstract Background Gastrulation is a uniquely metazoan character, and its genesis was arguably the key step that enabled the remarkable diversification within this clade. The process of gastrulation involves two tightly coupled events during embryogenesis of most metazoans. Morphogenesis produces a distinct internal epithelial layer in the embryo, and this epithelium becomes segregated as an endoderm/endomesodermal germ layer through the activation of a specific gene regulatory program. The developmental mechanisms that induced archenteron formation and led to the segregation of germ layers during metazoan evolution are unknown. But an increased understanding of development in early diverging taxa at the base of the metazoan tree may provide insights into the origins of these developmental mechanisms. Results In the anthozoan cnidarian Nematostella vectensis, initial archenteron formation begins with bottle cell-induced buckling of the blastula epithelium at the animal pole. Here, we show that bottle cell formation and initial gut invagination in Nematostella requires NvStrabismus (NvStbm, a maternally-expressed core component of the Wnt/Planar Cell Polarity (PCP pathway. The NvStbm protein is localized to the animal pole of the zygote, remains asymmetrically expressed through the cleavage stages, and becomes restricted to the apical side of invaginating bottle cells at the blastopore. Antisense morpholino-mediated NvStbm-knockdown blocks bottle cell formation and initial archenteron invagination, but it has no effect on Wnt/ß-catenin signaling-mediated endoderm cell fate specification. Conversely, selectively blocking Wnt/ß-catenin signaling inhibits endoderm cell fate specification but does not affect bottle cell formation and initial archenteron invagination. Conclusions Our results demonstrate that Wnt/PCP-mediated initial archenteron invagination can be uncoupled from Wnt/ß-catenin-mediated endoderm cell fate specification in
Chen, Xiankai
2017-10-17
In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet-triplet energy gap (ΔEST ) in strongly twisted structures usually translates into a small fluorescence oscillator strength, which can significantly decrease the emission quantum yield and limit efficiency in organic light-emitting diode devices. Here, based on the results of quantum-chemical calculations on TADF emitters composed of carbazole donor and 2,4,6-triphenyl-1,3,5-triazine acceptor moieties, a new strategy is proposed for the molecular design of efficient TADF emitters that combine a small ΔEST with a large fluorescence oscillator strength. Since this strategy goes beyond the traditional framework of structurally twisted, charge-transfer type emitters, importantly, it opens the way for coplanar molecules to be efficient TADF emitters. Here, a new emitter, composed of azatriangulene and diphenyltriazine moieties, is theoretically designed, which is coplanar due to intramolecular H-bonding interactions. The synthesis of this hexamethylazatriangulene-triazine (HMAT-TRZ) emitter and its preliminary photophysical characterizations point to HMAT-TRZ as a potential efficient TADF emitter.
Zhu, Pei-hua; Huang, Jing-yuan; Ye, Meng; Zheng, Zhe-lan
2014-09-01
To evaluate the left ventricular twist characteristics in patients with type 2 diabetes by using two-dimensional speckle tracking imaging (STI). Ninety-three patients with type 2 diabetes admitted in Zhejiang Hospital from May 2012 to September 2013 were enrolled. According to left ventricular ejection fraction (LVEF), patients were divided into two groups: normal left ventricular systolic function group (group A, LVEF≥0.50, n=46) and abnormal left ventricular systolic function group (group B, LVEF Consistency check for STI was conducted to assess its stability and reliability. The Peaktw, AVCtw, and MVOtw in group A were significantly elevated than those in normal controls (Pconsistency limit=-2.8-2.7; within measurer: R=0.964, bias=-0.2, 95% consistency limits=-2.7-2.2). STI can be used for early recognition of abnormal changes of cardiac function in type 2 diabetic mellitus patients, with high stability and reliability.
International Nuclear Information System (INIS)
Jaisankar, S.; Radhakrishnan, T.K.; Sheeba, K.N.; Suresh, S.
2009-01-01
Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater with full length Left-Right twist, twist fitted with rod and spacer at the trailing edge for lengths of 100, 200 and 300 mm for twist ratio 3 and 5 has been studied. The experimental data for plain tube collector has been compared with fundamental equation within a discrepancy of ±7.41% and ±14.97% for Nusselt number and friction factor, respectively. Result shows that the Nusselt number decreases by 11% and 19% for twist fitted with rod and twist with spacer, respectively, when compared with full length twist. Friction factor also decreases by 18% and 29% for twist fitted with rod and spacer, respectively, as compared with full length twist. The heat enhancement in twist fitted with rod at the trailing edge is maximum when compared with twist fitted with spacer because the swirl flow is maintained throughout the length of rod.
Probing the interlayer coupling of twisted bilayer MoS2 using photoluminescence spectroscopy.
Huang, Shengxi; Ling, Xi; Liang, Liangbo; Kong, Jing; Terrones, Humberto; Meunier, Vincent; Dresselhaus, Mildred S
2014-10-08
Two-dimensional molybdenum disulfide (MoS2) is a promising material for optoelectronic devices due to its strong photoluminescence emission. In this work, the photoluminescence of twisted bilayer MoS2 is investigated, revealing a tunability of the interlayer coupling of bilayer MoS2. It is found that the photoluminescence intensity ratio of the trion and exciton reaches its maximum value for the twisted angle 0° or 60°, while for the twisted angle 30° or 90° the situation is the opposite. This is mainly attributed to the change of the trion binding energy. The first-principles density functional theory analysis further confirms the change of the interlayer coupling with the twisted angle, which interprets our experimental results.
Unconfined twist : a simple method to prepare ultrafine grained metallic materials.
Energy Technology Data Exchange (ETDEWEB)
Zhao, Y. (Yonghao); Liao, Xiaozhou; Zhu, Y. T. (Yuntian Theodore)
2004-01-01
A new simple method - unconfined twist was employed to prepare ultrafine grained (UFG) Fe,wire. A coarse grained (CG) Fe wire with a diameter of 0.85 mm was fixed at one end, and twisted at the other end. After maximum twist before fracture, in the cross-sectional plane, concentrically deformed layers with a width of several micrometers formed surrounding the center axis of the wire. The near-surface deformed layers consist of lamella grains with a width in submicrometer range. In the longitudinal plane, deformed bands (with a width of several micrometers) formed uniformly, which were composed of lamella crystallites (with a width in submicrometer range). The tensile yield strength and ultimate strength of the twisted Fe wire are increased by about 150% and 100% compared with the values of its CG counterpart.
Leading twist moments of the neutron structure function F_2n
Energy Technology Data Exchange (ETDEWEB)
M. Osipenko; W. Melnitchouk; S. Simula; S. Kulagin; G. Ricco
2005-10-20
We perform a global analysis of neutron $F_2^n$ structure function data, obtained by combining proton and deuteron measurements over a large range of kinematics. From these data the lowest moments ($n \\leq 10$) of the leading twist neutron $F_2^n$ structure function are extracted. Particular attention is paid to nuclear effects in the deuteron, which become increasingly important for the higher moments. Our results for the nonsinglet, isovector $p - n$ combination of the leading twist moments are compared with those of available lattice simulations. We also determine the lowest few moments of the higher twist contributions, obtained by subtracting the leading twist from the total structure function, and analyze their isospin dependence.
New dualities and misleading anomaly matchings from outer-automorphism twists
Energy Technology Data Exchange (ETDEWEB)
Pal, Sridip; Song, Jaewon [Department of Physics, University of California, San Diego,La Jolla, CA 92093 (United States)
2017-03-29
We study four-dimensional N=1,2 superconformal theories in class S obtained by compactifying the 6d N=(2,0) theory on a Riemann surface C with outer-automorphism twist lines. From the pair-of-pants decompositions of C, we find various dual descriptions for the same theory having distinct gauge groups. We show that the various configurations of the twist line give rise to dual descriptions for the identical theory. We compute the ’t Hooft anomaly coefficients and the superconformal indices to test dualities. Surprisingly, we find that the class S theories with twist lines wrapping 1-cycles of C have the identical ’t Hooft anomalies as the ones without the twist line, whereas the superconformal indices differ. This provides a large set of examples where the anomaly matching is insufficient to test dualities.
Composite material bend-twist coupling for wind turbine blade applications
Walsh, Justin M.
Current efforts in wind turbine blade design seek to employ bend-twist coupling of composite materials for passive power control by twisting blades to feather. Past efforts in this area of study have proved to be problematic, especially in formulation of the bend-twist coupling coefficient alpha. Kevlar/epoxy, carbon/epoxy and glass/epoxy specimens were manufactured to study bend-twist coupling, from which numerical and analytical models could be verified. Finite element analysis was implemented to evaluate fiber orientation and material property effects on coupling magnitude. An analytical/empirical model was then derived to describe numerical results and serve as a replacement for the commonly used coupling coefficient alpha. Through the results from numerical and analytical models, a foundation for aeroelastic design of wind turbines blades utilizing biased composite materials is provided.
Innovation of Methods for Measurement and Modelling of Twisted Pair Parameters
Directory of Open Access Journals (Sweden)
Lukas Cepa
2011-01-01
Full Text Available The goal of this paper is to optimize a measurement methodology for the most accurate broadband modelling of characteristic impedance and other parameters for twisted pairs. Measured values and theirs comparison is presented in this article. Automated measurement facility was implemented at the Department of telecommunication of Faculty of electrical engineering of Czech technical university in Prague. Measurement facility contains RF switches allowing measurements up to 300 MHz or 1GHz. Measured twisted pair’s parameters can be obtained by measurement but for purposes of fundamental characteristics modelling is useful to define functions that model the properties of the twisted pair. Its primary and secondary parameters depend mostly on the frequency. For twisted pair deployment, we are interested in a frequency band range from 1 MHz to 100 MHz.
Families of vector-like deformations of relativistic quantum phase spaces, twists and symmetries
Energy Technology Data Exchange (ETDEWEB)
Meljanac, Daniel [Ruder Boskovic Institute, Division of Materials Physics, Zagreb (Croatia); Meljanac, Stjepan; Pikutic, Danijel [Ruder Boskovic Institute, Division of Theoretical Physics, Zagreb (Croatia)
2017-12-15
Families of vector-like deformed relativistic quantum phase spaces and corresponding realizations are analyzed. A method for a general construction of the star product is presented. The corresponding twist, expressed in terms of phase space coordinates, in the Hopf algebroid sense is presented. General linear realizations are considered and corresponding twists, in terms of momenta and Poincare-Weyl generators or gl(n) generators are constructed and R-matrix is discussed. A classification of linear realizations leading to vector-like deformed phase spaces is given. There are three types of spaces: (i) commutative spaces, (ii) κ-Minkowski spaces and (iii) κ-Snyder spaces. The corresponding star products are (i) associative and commutative (but non-local), (ii) associative and non-commutative and (iii) non-associative and non-commutative, respectively. Twisted symmetry algebras are considered. Transposed twists and left-right dual algebras are presented. Finally, some physical applications are discussed. (orig.)
κ-Minkowski spacetime as the result of Jordanian twist deformation
International Nuclear Information System (INIS)
Borowiec, A.; Pachol, A.
2009-01-01
Two one-parameter families of twists providing κ-Minkowski * product deformed spacetime are considered: Abelian and Jordanian. We compare the derivation of quantum Minkowski space from two perspectives. The first one is the Hopf module algebra point of view, which is strictly related with Drinfeld's twisting tensor technique. The other one relies on an appropriate extension of ''deformed realizations'' of nondeformed Lorentz algebra by the quantum Minkowski algebra. This extension turns out to be de Sitter Lie algebra. We show the way both approaches are related. The second path allows us to calculate deformed dispersion relations for toy models ensuing from different twist parameters. In the Abelian case, one recovers κ-Poincare dispersion relations having numerous applications in doubly special relativity. Jordanian twists provide a new type of dispersion relations which in the minimal case (related to Weyl-Poincare algebra) takes an energy-dependent linear mass deformation form.
Level-rank duality of untwisted and twisted D-branes
International Nuclear Information System (INIS)
Naculich, Stephen G.; Schnitzer, Howard J.
2006-01-01
Level-rank duality of untwisted and twisted D-branes of WZW models is explored. We derive the relation between D0-brane charges of level-rank dual untwisted D-branes of su-bar (N) K and sp-bar (n) k , and of level-rank dual twisted D-branes of su-bar (2n+1) 2k+1 . The analysis of level-rank duality of twisted D-branes of su-bar (2n+1) 2k+1 is facilitated by their close relation to untwisted D-branes of sp-bar (n) k . We also demonstrate level-rank duality of the spectrum of an open string stretched between untwisted or twisted D-branes in each of these cases
Structural and electronic transformation in low-angle twisted bilayer graphene
Gargiulo, Fernando; Yazyev, Oleg V.
2018-01-01
Experiments on bilayer graphene unveiled a fascinating realization of stacking disorder where triangular domains with well-defined Bernal stacking are delimited by a hexagonal network of strain solitons. Here we show by means of numerical simulations that this is a consequence of a structural transformation of the moiré pattern inherent to twisted bilayer graphene taking place at twist angles θ below a crossover angle θ\\star=1.2\\circ . The transformation is governed by the interplay between the interlayer van der Waals interaction and the in-plane strain field, and is revealed by a change in the functional form of the twist energy density. This transformation unveils an electronic regime characteristic of vanishing twist angles in which the charge density converges, though not uniformly, to that of ideal bilayer graphene with Bernal stacking. On the other hand, the stacking domain boundaries form a distinct charge density pattern that provides the STM signature of the hexagonal solitonic network.
A twisted flux-tube model for solar prominences. I. General properties
International Nuclear Information System (INIS)
Priest, E.R.; Hood, A.W.; Anzer, U.
1989-01-01
It is proposed that a solar prominence consists of cool plasma supported in a large-scale curved and twisted magnetic flux tube. As long as the flux tube is untwisted, its curvature is concave toward the solar surface, and so it cannot support dense plasma against gravity. However, when it is twisted sufficiently, individual field lines may acquire a convex curvature near their summits and so provide support. Cool plasma then naturally tends to accumulate in such field line dips either by injection from below or by thermal condensation. As the tube is twisted up further or reconnection takes place below the prominence, one finds a transition from normal to inverse polarity. When the flux tube becomes too long or is twisted too much, it loses stability and its true magnetic geometry as an erupting prominence is revealed more clearly. 56 refs
Demonstration of an elastically coupled twist control concept for tilt rotor blade application
Lake, R. C.; Nixon, M. W.; Wilbur, M. L.; Singleton, J. D.; Mirick, P. H.
1994-01-01
The purpose of this Note is to present results from an analytic/experimental study that investigated the potential for passively changing blade twist through the use of extension-twist coupling. A set of composite model rotor blades was manufactured from existing blade molds for a low-twist metal helicopter rotor blade, with a view toward establishing a preliminary proof concept for extension-twist-coupled rotor blades. Data were obtained in hover for both a ballasted and unballasted blade configuration in sea-level atmospheric conditions. Test data were compared with results obtained from a geometrically nonlinear analysis of a detailed finite element model of the rotor blade developed in MSC/NASTRAN.
Homoclinic Orbits for a Class of Nonperiodic Hamiltonian Systems with Some Twisted Conditions
Directory of Open Access Journals (Sweden)
Qi Wang
2013-01-01
Full Text Available By the Maslov index theory, we will study the existence and multiplicity of homoclinic orbits for a class of asymptotically linear nonperiodic Hamiltonian systems with some twisted conditions on the Hamiltonian functions.
Families of vector-like deformations of relativistic quantum phase spaces, twists and symmetries
International Nuclear Information System (INIS)
Meljanac, Daniel; Meljanac, Stjepan; Pikutic, Danijel
2017-01-01
Families of vector-like deformed relativistic quantum phase spaces and corresponding realizations are analyzed. A method for a general construction of the star product is presented. The corresponding twist, expressed in terms of phase space coordinates, in the Hopf algebroid sense is presented. General linear realizations are considered and corresponding twists, in terms of momenta and Poincare-Weyl generators or gl(n) generators are constructed and R-matrix is discussed. A classification of linear realizations leading to vector-like deformed phase spaces is given. There are three types of spaces: (i) commutative spaces, (ii) κ-Minkowski spaces and (iii) κ-Snyder spaces. The corresponding star products are (i) associative and commutative (but non-local), (ii) associative and non-commutative and (iii) non-associative and non-commutative, respectively. Twisted symmetry algebras are considered. Transposed twists and left-right dual algebras are presented. Finally, some physical applications are discussed. (orig.)
Families of vector-like deformations of relativistic quantum phase spaces, twists and symmetries
Meljanac, Daniel; Meljanac, Stjepan; Pikutić, Danijel
2017-12-01
Families of vector-like deformed relativistic quantum phase spaces and corresponding realizations are analyzed. A method for a general construction of the star product is presented. The corresponding twist, expressed in terms of phase space coordinates, in the Hopf algebroid sense is presented. General linear realizations are considered and corresponding twists, in terms of momenta and Poincaré-Weyl generators or gl(n) generators are constructed and R-matrix is discussed. A classification of linear realizations leading to vector-like deformed phase spaces is given. There are three types of spaces: (i) commutative spaces, (ii) κ -Minkowski spaces and (iii) κ -Snyder spaces. The corresponding star products are (i) associative and commutative (but non-local), (ii) associative and non-commutative and (iii) non-associative and non-commutative, respectively. Twisted symmetry algebras are considered. Transposed twists and left-right dual algebras are presented. Finally, some physical applications are discussed.
Direct Synthesis of Medium-Bridged Twisted Amides via a Transannular Cyclization Strategy
Szostak, Michal; Aubé, Jeffrey
2009-01-01
The sequential RCM to construct a challenging medium-sized ring followed by a transannular cyclization across a medium-sized ring delivers previously unattainable twisted amides from simple acyclic precursors. PMID:19708701
Laminar flow heat transfer studies in a twisted square duct for ...
Indian Academy of Sciences (India)
Department of Mechanical Engineering, Indian Institute of Technology,. Bombay 400 ... boundary conditions using commercially available software. ... Chang et al (1988) used numerical method to study laminar flow in a twisted elliptic tube for.
Dynamics and control of twisting bi-stable structures
Arrieta, Andres F.; van Gemmeren, Valentin; Anderson, Aaron J.; Weaver, Paul M.
2018-02-01
Compliance-based morphing structures have the potential to offer large shape adaptation, high stiffness and low weight, while reducing complexity, friction, and scalability problems of mechanism based systems. A promising class of structure that enables these characteristics are multi-stable structures given their ability to exhibit large deflections and rotations without the expensive need for continuous actuation, with the latter only required intermittently. Furthermore, multi-stable structures exhibit inherently fast response due to the snap-through instability governing changes between stable states, enabling rapid configuration switching between the discrete number of programmed shapes of the structure. In this paper, the design and utilisation of the inherent nonlinear dynamics of bi-stable twisting I-beam structures for actuation with low strain piezoelectric materials is presented. The I-beam structure consists of three compliant components assembled into a monolithic single element, free of moving parts, and showing large deflections between two stable states. Finite element analysis is utilised to uncover the distribution of strain across the width of the flange, guiding the choice of positioning for piezoelectric actuators. In addition, the actuation authority is maximised by calculating the generalised coupling coefficient for different positions of the piezoelectric actuators. The results obtained are employed to tailor and test I-beam designs exhibiting desired large deflection between stable states, while still enabling the activation of snap-through with the low strain piezoelectric actuators. To this end, the dynamic response of the I-beams to piezoelectric excitation is investigated, revealing that resonant excitations are insufficient to dynamically trigger snap-through. A novel bang-bang control strategy, which exploits the nonlinear dynamics of the structure successfully triggers both single and constant snap-through between the stable states
Transcription factors zeb1, twist and snai1 in breast carcinoma
International Nuclear Information System (INIS)
Soini, Ylermi; Tuhkanen, Hanna; Sironen, Reijo; Virtanen, Ismo; Kataja, Vesa; Auvinen, Päivi; Mannermaa, Arto; Kosma, Veli-Matti
2011-01-01
Epitheliomesenchymal transition (EMT) is the process where cancer cells attain fibroblastic features and are thus able to invade neighboring tissues. Transcriptional factors zeb1, snai1 and twist regulate EMT. We used immunohistochemistry to investigate the expression of zeb1, twist and snai1 in tumor and stromal compartments by in a large set of breast carcinomas. The results were compared with estrogen and progesterone receptor status, HER2 amplification, grade, histology, TNM status and survival of the patients. Nuclear expression for twist was seen in the epithelial tumor cell compartment in 3.6% and for snai1 in 3.1% of the cases while zeb1 was not detected at all in these areas. In contrast, the tumor stromal compartment showed nuclear zeb1 and twist expression in 75% and 52.4% of the cases, respectively. Although rare, nuclear expression of twist in the epithelial tumor cell compartment was associated with a poor outcome of the patients (p = 0.054 log rank, p = 0.013, Breslow, p = 0.025 Tarone-Ware). Expression of snai1, or expression of zeb1 or twist in the stromal compartment did not have any prognostic significance. Furthermore, none of these factors associated with the size of the tumors, nor with the presence of axillary or distant metastases. Expression of zeb1 and twist in the stromal compartment was positively associated with a positive estrogen or progesterone receptor status of the tumors. Stromal zeb1 expression was significantly lower in ductal in situ carcinomas than in invasive carcinomas (p = 0.020). Medullary carcinomas (p = 0.017) and mucinous carcinomas (p = 0.009) had a lower stromal expression of zeb1 than ductal carcinomas. Stromal twist expression was also lower in mucinous (p = 0.017) than in ductal carcinomas. Expression of transcriptional factors zeb1 and twist mainly occur in the stromal compartment of breast carcinomas, possibly representing two populations of cells; EMT transformed neoplastic cells and stromal fibroblastic cells
Calculations of higher twist distribution functions in the MIT bag model
International Nuclear Information System (INIS)
Signal, A.I.
1997-01-01
We calculate all twist-2, -3 and -4 parton distribution functions involving two quark correlations using the wave function of the MIT bag model. The distributions are evolved up to experimental scales and combined to give the various nucleon structure functions. Comparisons with recent experimental data on higher twist structure functions at moderate values of Q 2 give good agreement with the calculated structure functions. (orig.)
Analysis of Twisting of Cellulose Nanofibrils in Atomistic Molecular Dynamics Simulations
DEFF Research Database (Denmark)
Paavilainen, S.; Rog, T.; Vattulainen, I.
2011-01-01
We use atomistic molecular dynamics simulations to study the crystal structure of cellulose nanofibrils, whose sizes are comparable with the crystalline parts in commercial nanocellulose. The simulations show twisting, whose rate of relaxation is strongly temperature dependent. Meanwhile......, no significant bending or stretching of nanocellulose is discovered. Considerations of atomic-scale interaction patterns bring about that the twisting arises from hydrogen bonding within and between the chains in a fibril....
One-dimensional structures behind twisted and untwisted superYang-Mills theory
Baulieu, Laurent
2011-01-01
We give a one-dimensional interpretation of the four-dimensional twisted N=1 superYang-Mills theory on a Kaehler manifold by performing an appropriate dimensional reduction. We prove the existence of a 6-generator superalgebra, which does not possess any invariant Lagrangian but contains two different subalgebras that determine the twisted and untwisted formulations of the N=1 superYang-Mills theory.
On the description of exclusive processes beyond the leading twist approximation
International Nuclear Information System (INIS)
Anikin, I.V.; Ivanov, D.Yu.; Pire, B.; Szymanowski, L.; Wallon, S.
2010-01-01
We describe hard exclusive processes beyond the leading twist approximation in a framework based on the Taylor expansion of the amplitude around the dominant light-cone directions. This naturally introduces an appropriate set of non-perturbative correlators whose number is minimalized after taking into account QCD equations of motion and the invariance under rotation on the light-cone. We exemplify this method at the twist 3 level and show that the coordinate and momentum space descriptions are fully equivalent.
On the description of exclusive processes beyond the leading twist approximation
Energy Technology Data Exchange (ETDEWEB)
Anikin, I.V. [Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna (Russian Federation); Ivanov, D.Yu. [Institute of Mathematics, 630090 Novosibirsk (Russian Federation); Pire, B., E-mail: pire@cpht.polytechnique.f [CPhT, Ecole Polytechnique, CNRS, F-91128 Palaiseau (France); Szymanowski, L. [Soltan Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw (Poland); Wallon, S. [LPT, Universite d' Orsay, CNRS, 91404 Orsay (France); UPMC Univ. Paris 6, Faculte de Physique, 4 place Jussieu, 75252 Paris Cedex 05 (France)
2010-01-04
We describe hard exclusive processes beyond the leading twist approximation in a framework based on the Taylor expansion of the amplitude around the dominant light-cone directions. This naturally introduces an appropriate set of non-perturbative correlators whose number is minimalized after taking into account QCD equations of motion and the invariance under rotation on the light-cone. We exemplify this method at the twist 3 level and show that the coordinate and momentum space descriptions are fully equivalent.
High Efficiency Large-Angle Pancharatnam Phase Deflector Based on Dual Twist Design
2016-12-16
construction and characterization of a ±40° beam steering device with 90% diffraction efficiency based on our dual-twist design at 633nm wavelength...N. & Escuti, M. J. Achromatic Wollaston prism beam splitter using polarization gratings. Opt. Lett. 41, 4461–4463 (2016). 13. Slussarenko, S., et...High-efficiency large-angle Pancharatnam phase deflector based on dual-twist design Kun Gao1, Colin McGinty1, Harold Payson2, Shaun Berry2, Joseph
One-dimensional structures behind twisted and untwisted super Yang-Mills theory
Energy Technology Data Exchange (ETDEWEB)
Baulieu, Laurent [CERN, Geneve (Switzerland). Theoretical Div.; Toppan, Francesco, E-mail: baulieu@lpthe.jussieu.f, E-mail: toppan@cbpf.b [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)
2010-07-01
We give a one-dimensional interpretation of the four-dimensional twisted N = 1 super Yang-Mills theory on a Kaehler manifold by performing an appropriate dimensional reduction. We prove the existence of a 6-generator superalgebra, which does not possess any invariant Lagrangian but contains two different subalgebras that determine the twisted and untwisted formulations of the N = 1 super Yang-Mills theory. (author)
Tilting-Twisting-Rolling: a pen-based technique for compass geometric construction
Institute of Scientific and Technical Information of China (English)
Fei LYU; Feng TIAN; Guozhong DAI; Hongan WANG
2017-01-01
This paper presents a new pen-based technique,Tilting-Twisting-Rolling,to support compass geometric construction.By leveraging the 3D orientation information and 3D rotation information of a pen,this technique allows smooth pen action to complete multi-step geometric construction without switching task states.Results from a user study show this Tilting-Twisting-Rolling technique can improve user performance and user experience in compass geometric construction.
One-dimensional structures behind twisted and untwisted super Yang-Mills theory
International Nuclear Information System (INIS)
Baulieu, Laurent
2010-01-01
We give a one-dimensional interpretation of the four-dimensional twisted N = 1 super Yang-Mills theory on a Kaehler manifold by performing an appropriate dimensional reduction. We prove the existence of a 6-generator superalgebra, which does not possess any invariant Lagrangian but contains two different subalgebras that determine the twisted and untwisted formulations of the N = 1 super Yang-Mills theory. (author)
Scaling and χPT description of pions from Nf=2 twisted mass QCD
International Nuclear Information System (INIS)
Dimopoulos, Petros; Frezzotti, Roberto; Herdoiza, Gregorio; Jansen, Karl; Michael, Chris; Urbach, Carsten; Bonn Univ.
2009-12-01
We study light-quark observables by means of dynamical lattice QCD simulations using two flavours of twisted mass fermions at maximal twist. We employ chiral perturbation theory to describe our data for the pion mass and decay constant. In this way, we extract precise determinations for the low-energy constants of the effective theory as well as for the light-quark mass and the chiral condensate. (orig.)
First results with two light flavours of quarks with maximally twisted mass
International Nuclear Information System (INIS)
Jansen, K.; Urbach, C.
2006-10-01
We report on first results of an ongoing effort to simulate lattice QCD with two degenerate flavours of quarks by means of the twisted mass formulation tuned to maximal twist. By utilising recent improvements of the HMC algorithm, pseudo-scalar masses well below 300 MeV are simulated on volumes L 3 .T with T=2L and L>2 fm and at values of the lattice spacing a f =2+1+1 flavours are discussed. (orig.)
Nucleon scalar matrix elements with N{sub f}=2+1+1 twisted mass fermions
Energy Technology Data Exchange (ETDEWEB)
Dinter, Simon; Drach, Vincent; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2011-12-15
We investigate scalar matrix elements of the nucleon using N{sub f}=2+1+1 flavors of maximally twisted mass fermions at a fixed value of the lattice spacing of a{approx}0.078 fm. We compute disconnected contributions to the relevant three-point functions using an efficient noise reduction technique. Using these methods together with an only multiplicative renormalization applicable for twisted mass fermions, allows us to obtain accurate results in the light and strange sector. (orig.)
Impact of higher twist terms on the analysis of scaling violation
International Nuclear Information System (INIS)
Barnett, R.M.
1979-09-01
A critical discussion is given of analyses of scaling violation in deep-inelastic scattering in the context of QCD. Several possible approaches are examined. Higher twist contributions are defined, and it is shown that they can have a crucial impact on tests of QCD. Higher twist terms can dramatically affect R = sigma/sub L//sigma/sub T/. QCD may be harder to test than previously realized. 17 references
Separation of minimum and higher twist in photoproduction of high-pT mesons
International Nuclear Information System (INIS)
Apsimon, R.J.; Flower, P.S.; Hallewell, G.; Morris, J.A.G.; Morris, J.V.; Paterson, C.N.; Sharp, P.H.; Atkinson, M.; Brook, N.; Coyle, P.; Dickinson, B.; Donnachie, A.; Doyle, A.T.; Ellison, R.J.; Foster, J.M.; Hughes-Jones, R.E.; Ibbotson, M.; Kolya, S.D.; Lafferty, G.D.; McCann, H.; McManus, C.; Mercer, D.; Ottewell, P.J.; Reid, D.; Thompson, R.J.; Waterhouse, J.; Barberis, D.; Davenport, M.; Eades, J.; Ingelman, G.; McClatchey, R.; Brodbeck, T.J.; Charity, T.; Clegg, A.B.; Henderson, R.C.W.; Hickman, M.T.; Keemer, N.R.; Newton, D.; O'Connor, A.; Wilson, G.W.; Danaher, S.; Galbraith, W.; Thacker, N.A.; Thompson, L.; Diekmann, B.; Gapp, C.; Gebert, F.; Heinloth, K.; Hoeger, K.C.; Holzkamp, A.; Holzkamp, S.; Jakob, H.P.; Joseph, D.; Kingler, J.; Koersgen, G.; Oedingen, R.; Paul, E.; Rotscheidt, H.; Soeldner-Rembold, S.; Weigend, A.S.
1991-01-01
Photo- and hadroproduction data in the beam energy range 65-175 GeV have been studied with a view to isolating higher-twist processes in photoproduction from other point-like and hadron-like contributions. With selection of charged tracks having p T >2 GeV/c and 0.28 F <0.84 indications of a higher twist contribution have been found at a level that is consistent with QCD expectations. (orig.)
Directory of Open Access Journals (Sweden)
Fang Fang
2018-05-01
Full Text Available In geometrically frustrated clusters of polyhedra, gaps between faces can be closed without distorting the polyhedra by the long established method of discrete curvature, which consists of curving the space into a fourth dimension, resulting in a dihedral angle at the joint between polyhedra in 4D. An alternative method—the twist method—has been recently suggested for a particular case, whereby the gaps are closed by twisting the cluster in 3D, resulting in an angular offset of the faces at the joint between adjacent polyhedral. In this paper, we show the general applicability of the twist method, for local clusters, and present the surprising result that both the required angle of the twist transformation and the consequent angle at the joint are the same, respectively, as the angle of bending to 4D in the discrete curvature and its resulting dihedral angle. The twist is therefore not only isomorphic, but isogonic (in terms of the rotation angles to discrete curvature. Our results apply to local clusters, but in the discussion we offer some justification for the conjecture that the isomorphism between twist and discrete curvature can be extended globally. Furthermore, we present examples for tetrahedral clusters with three-, four-, and fivefold symmetry.
Wilkie, W. Keats; Belvin, W. Keith; Park, K. C.
1996-01-01
A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consists of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for dynamics simulation using numerical integration. The twist actuation responses for three conceptual fullscale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.
Wilkie, W. Keats; Park, K. C.
1996-01-01
A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consist of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for numerical integration. The twist actuation responses for three conceptual full-scale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.
Directory of Open Access Journals (Sweden)
Anca Dana Dobrian
2012-08-01
Full Text Available The Twist proteins (Twist-1 and -2 are highly conserved developmental proteins with key roles for the transcriptional regulation in mesenchymal cell lineages. They belong to the super-family of bHLH proteins and exhibit bi-functional roles as both activators and repressors of gene transcription. The Twist proteins are expressed at low levels in adult tissues but may become abundantly re-expressed in cells undergoing malignant transformation. This observation prompted extensive research on the roles of Twist proteins in cancer progression and metastasis. Very recent studies indicate a novel role for Twist-1 as a potential regulator of adipose tissue remodeling and inflammation. Several studies suggested that developmental genes are important determinants of obesity, fat distribution and remodeling capacity of different adipose depots. Twist-1 is abundantly and selectively expressed in the adult adipose tissue and its constitutive expression is significantly higher in subcutaneous vs. visceral fat in both mice and humans. Moreover, Twist1 expression is strongly correlated with BMI and insulin resistance in humans. However, the functional roles and transcriptional downstream targets of Twist1 in adipose tissue are largely unexplored. The purpose of this review is to highlight the major findings related to Twist1 expression in different fat depots and cellular components of adipose tissue and to discuss the potential mechanisms suggesting a role for Twist1 in adipose tissue metabolism, inflammation and remodeling.
Haftmann, Claudia; Stittrich, Anna-Barbara; Zimmermann, Jakob; Fang, Zhuo; Hradilkova, Kristyna; Bardua, Markus; Westendorf, Kerstin; Heinz, Gitta A; Riedel, René; Siede, Julia; Lehmann, Katrin; Weinberger, Esther E; Zimmel, David; Lauer, Uta; Häupl, Thomas; Sieper, Joachim; Backhaus, Marina; Neumann, Christian; Hoffmann, Ute; Porstner, Martina; Chen, Wei; Grün, Joachim R; Baumgrass, Ria; Matz, Mareen; Löhning, Max; Scheffold, Alexander; Wittmann, Jürgen; Chang, Hyun-Dong; Rajewsky, Nikolaus; Jäck, Hans-Martin; Radbruch, Andreas; Mashreghi, Mir-Farzin
2015-04-01
Repeatedly activated T helper 1 (Th1) cells present during chronic inflammation can efficiently adapt to the inflammatory milieu, for example, by expressing the transcription factor Twist1, which limits the immunopathology caused by Th1 cells. Here, we show that in repeatedly activated murine Th1 cells, Twist1 and T-bet induce expression of microRNA-148a (miR-148a). miR-148a regulates expression of the proapoptotic gene Bim, resulting in a decreased Bim/Bcl2 ratio. Inhibition of miR-148a by antagomirs in repeatedly activated Th1 cells increases the expression of Bim, leading to enhanced apoptosis. Knockdown of Bim expression by siRNA in miR-148a antagomir-treated cells restores viability of the Th1 cells, demonstrating that miR-148a controls survival by regulating Bim expression. Thus, Twist1 and T-bet not only control the differentiation and function of Th1 cells, but also their persistence in chronic inflammation. © 2014 The Authors. European Journal of Immunology published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
The possibility of superconductivity in twisted bilayer graphene
Energy Technology Data Exchange (ETDEWEB)
Manaf, Muhamad Nasruddin, E-mail: muhamad.nasruddin.manaf@mail.ugm.ac.id; Santoso, Iman, E-mail: iman.santoso@ugm.ac.id; Hermanto, Arief [Jurusan Fisika, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Gadjah Mada, Bulaksumur 55281, Yogyakarta (Indonesia); Yayasan Hikmah Teknosains, Jl. Kaliurang Km 5,3 Gg. Pamungkas No. 16 A, Yogyakarta (Indonesia)
2015-09-30
We discuss the possibility of superconductivity in Twisted Bilayer Graphene (TBG). In this study we use TBG model with commensurate rotation θ=1.16° in which the van-Hove singularities (VHS) arise at 6 meV from the Fermi level. We use BCS standard formula that include Density of States (DOS) to calculate the critical temperature (T{sub C}). Based on our calculation we predict that superconductivity will not arise in Pristine TBG because pairing potential has infinity value. In this situation, Dirac Fermions do not interact with each other since they do not form the bound states. Superconductvity may arise when the Fermi level is shifted towards the VHS. Based on this calculation, we predict that T{sub C} has value between 0.04 K and 0.12 K. The low value of T{sub C} is due to highly energetic of in plane phonon vibration which reduce the effective electron-phonon coupling. We conclude that doped TBG is candidate for Dirac Fermion superconductor.
Slow wave structures using twisted waveguides for charged particle applications
Kang, Yoon W.; Fathy, Aly E.; Wilson, Joshua L.
2012-12-11
A rapidly twisted electromagnetic accelerating structure includes a waveguide body having a central axis, one or more helical channels defined by the body and disposed around a substantially linear central axial channel, with central portions of the helical channels merging with the linear central axial channel. The structure propagates electromagnetic waves in the helical channels which support particle beam acceleration in the central axial channel at a phase velocity equal to or slower than the speed of light in free space. Since there is no variation in the shape of the transversal cross-section along the axis of the structure, inexpensive mechanical fabrication processes can be used to form the structure, such as extrusion, casting or injection molding. Also, because the field and frequency of the resonant mode depend on the whole structure rather than on dimensional tolerances of individual cells, no tuning of individual cells is needed. Accordingly, the overall operating frequency may be varied with a tuning/phase shifting device located outside the resonant waveguide structure.
Optimization of aerodynamic efficiency for twist morphing MAV wing
Directory of Open Access Journals (Sweden)
N.I. Ismail
2014-06-01
Full Text Available Twist morphing (TM is a practical control technique in micro air vehicle (MAV flight. However, TM wing has a lower aerodynamic efficiency (CL/CD compared to membrane and rigid wing. This is due to massive drag penalty created on TM wing, which had overwhelmed the successive increase in its lift generation. Therefore, further CL/CDmax optimization on TM wing is needed to obtain the optimal condition for the morphing wing configuration. In this paper, two-way fluid–structure interaction (FSI simulation and wind tunnel testing method are used to solve and study the basic wing aerodynamic performance over (non-optimal TM, membrane and rigid wings. Then, a multifidelity data metamodel based design optimization (MBDO process is adopted based on the Ansys-DesignXplorer frameworks. In the adaptive MBDO process, Kriging metamodel is used to construct the final multifidelity CL/CD responses by utilizing 23 multi-fidelity sample points from the FSI simulation and experimental data. The optimization results show that the optimal TM wing configuration is able to produce better CL/CDmax magnitude by at least 2% than the non-optimal TM wings. The flow structure formation reveals that low TV strength on the optimal TM wing induces low CD generation which in turn improves its overall CL/CDmax performance.
Chiral cell sliding drives left-right asymmetric organ twisting
Inaki, Mikiko; Hatori, Ryo; Nakazawa, Naotaka; Okumura, Takashi; Ishibashi, Tomoki; Kikuta, Junichi; Ishii, Masaru
2018-01-01
Polarized epithelial morphogenesis is an essential process in animal development. While this process is mostly attributed to directional cell intercalation, it can also be induced by other mechanisms. Using live-imaging analysis and a three-dimensional vertex model, we identified ‘cell sliding,’ a novel mechanism driving epithelial morphogenesis, in which cells directionally change their position relative to their subjacent (posterior) neighbors by sliding in one direction. In Drosophila embryonic hindgut, an initial left-right (LR) asymmetry of the cell shape (cell chirality in three dimensions), which occurs intrinsically before tissue deformation, is converted through LR asymmetric cell sliding into a directional axial twisting of the epithelial tube. In a Drosophila inversion mutant showing inverted cell chirality and hindgut rotation, cell sliding occurs in the opposite direction to that in wild-type. Unlike directional cell intercalation, cell sliding does not require junctional remodeling. Cell sliding may also be involved in other cases of LR-polarized epithelial morphogenesis. PMID:29891026
Nucleon structure by Lattice QCD computations with twisted mass fermions
International Nuclear Information System (INIS)
Harraud, P.A.
2010-11-01
Understanding the structure of the nucleon from quantum chromodynamics (QCD) is one of the greatest challenges of hadronic physics. Only lattice QCD allows to determine numerically the values of the observables from ab-initio principles. This thesis aims to study the nucleon form factors and the first moments of partons distribution functions by using a discretized action with twisted mass fermions. As main advantage, the discretization effects are suppressed at first order in the lattice spacing. In addition, the set of simulations allows a good control of the systematical errors. After reviewing the computation techniques, the results obtained for a wide range of parameters are presented, with lattice spacings varying from 0.0056 fm to 0.089 fm, spatial volumes from 2.1 up to 2.7 fm and several pion masses in the range of 260-470 MeV. The vector renormalization constant was determined in the nucleon sector with improved precision. Concerning the electric charge radius, we found a finite volume effect that provides a key towards an explanation of the chiral dependence of the physical point. The results for the magnetic moment, the axial charge, the magnetic and axial charge radii, the momentum and spin fractions carried by the quarks show no dependence on the lattice spacing nor volume. In our range of pion masses, their values show a deviation from the experimental values. Their chiral behaviour do not exhibit the curvature predicted by the chiral perturbation theory which could explain the apparent discrepancy. (author)
The possibility of superconductivity in twisted bilayer graphene
International Nuclear Information System (INIS)
Manaf, Muhamad Nasruddin; Santoso, Iman; Hermanto, Arief
2015-01-01
We discuss the possibility of superconductivity in Twisted Bilayer Graphene (TBG). In this study we use TBG model with commensurate rotation θ=1.16° in which the van-Hove singularities (VHS) arise at 6 meV from the Fermi level. We use BCS standard formula that include Density of States (DOS) to calculate the critical temperature (T C ). Based on our calculation we predict that superconductivity will not arise in Pristine TBG because pairing potential has infinity value. In this situation, Dirac Fermions do not interact with each other since they do not form the bound states. Superconductvity may arise when the Fermi level is shifted towards the VHS. Based on this calculation, we predict that T C has value between 0.04 K and 0.12 K. The low value of T C is due to highly energetic of in plane phonon vibration which reduce the effective electron-phonon coupling. We conclude that doped TBG is candidate for Dirac Fermion superconductor
A topologically twisted index for three-dimensional supersymmetric theories
International Nuclear Information System (INIS)
Benini, Francesco; Zaffaroni, Alberto
2015-01-01
We provide a general formula for the partition function of three-dimensional N=2 gauge theories placed on S 2 ×S 1 with a topological twist along S 2 , which can be interpreted as an index for chiral states of the theories immersed in background magnetic fields. The result is expressed as a sum over magnetic fluxes of the residues of a meromorphic form which is a function of the scalar zero-modes. The partition function depends on a collection of background magnetic fluxes and fugacities for the global symmetries. We illustrate our formula in many examples of 3d Yang-Mills-Chern-Simons theories with matter, including Aharony and Giveon-Kutasov dualities. Finally, our formula generalizes to Ω-backgrounds, as well as two-dimensional theories on S 2 and four-dimensional theories on S 2 ×T 2 . In particular this provides an alternative way to compute genus-zero A-model topological amplitudes and Gromov-Witten invariants.
A model for cytoplasmic rheology consistent with magnetic twisting cytometry.
Butler, J P; Kelly, S M
1998-01-01
Magnetic twisting cytometry is gaining wide applicability as a tool for the investigation of the rheological properties of cells and the mechanical properties of receptor-cytoskeletal interactions. Current technology involves the application and release of magnetically induced torques on small magnetic particles bound to or inside cells, with measurements of the resulting angular rotation of the particles. The properties of purely elastic or purely viscous materials can be determined by the angular strain and strain rate, respectively. However, the cytoskeleton and its linkage to cell surface receptors display elastic, viscous, and even plastic deformation, and the simultaneous characterization of these properties using only elastic or viscous models is internally inconsistent. Data interpretation is complicated by the fact that in current technology, the applied torques are not constant in time, but decrease as the particles rotate. This paper describes an internally consistent model consisting of a parallel viscoelastic element in series with a parallel viscoelastic element, and one approach to quantitative parameter evaluation. The unified model reproduces all essential features seen in data obtained from a wide variety of cell populations, and contains the pure elastic, viscoelastic, and viscous cases as subsets.
Direct transfer and Raman characterization of twisted graphene bilayer
International Nuclear Information System (INIS)
Othmen, R.; Arezki, H.; Boutchich, M.; Ajlani, H.; Oueslati, M.; Cavanna, A.; Madouri, A.
2015-01-01
Twisted bilayer graphene (tBLG) is constituted of a two-graphene layer with a mismatch angle θ between the two hexagonal structures. It has recently attracted much attention—thanks to its diverse electronic and optical properties. Here, we study the tBLG fabricated by the direct transfer of graphene monolayer prepared by chemical vapor deposition (CVD) onto another CVD graphene layer remaining attached to the copper foil. We show that high quality and homogeneous tBLG can be obtained by the direct transfer which prevents interface contamination. In this situation, the top graphene layer plays a supporting mechanical role to the bottom graphene layer as confirmed by optical microscopy, scanning electron microscopy, and Raman spectroscopy measurements. The effect of annealing tBLG was also investigated using micro-Raman spectroscopy. The Raman spectra exhibit a splitting of the G peak as well as a change in the 2D band shape indicating a possible decoupling of the two monolayers. We attribute these changes to the different interactions of the top and bottom layers with the substrate
A new concept for active bistable twisting structures
Schultz, Marc R.
2005-05-01
A novel type of morphing structure capable of a large change in shape with a small energy input is discussed in this paper. The considered structures consist of two curved shells that are joined in a specific manner to form a bistable airfoil-like structure. The two stable shapes have a difference in axial twist, and the structure may be transformed between the stable shapes by a simple snap-through action. The benefit of a bistable structure of this type is that, if the stable shapes are operational shapes, power is needed only to transform the structure from one shape to another. The discussed structures could be used in aerodynamic applications such as morphing wings, or as aerodynamic control surfaces. The investigation discussed in this paper considers both experiment and finite-element analysis. Several graphite-epoxy composite and one steel device were created as proof-of-concept models. To demonstrate active control of these structures, piezocomposite actuators were applied to one of the composite structures and used to transform the structure between stable shapes. The analysis was used to compare the predicted shapes with the experimental shapes, and to study how changes to the geometric input values affected the shape and operational characteristics of the structures. The predicted shapes showed excellent agreement with the experimental shapes, and the results of the parametric study suggest that the shapes and the snap-through characteristics can be easily tailored to meet specific needs.
Shrink, twist, ripple and melt: Studies of frustrated liquid crystals
Fernsler, Jonathan G.
Complex structures can arise out of a simple system with more than one competing influence on its behavior. The protypical example of this is the two-dimensional triangular lattice Ising model. The ferromagnetic model has two simple degenerate ground states of all spins up or down, but the antiferromagnetic model is a frustrated system. Its geometry does not allow satisfaction of the antiferro condition everywhere, which produces complex ordered structures with dimerization of the spins [1]. Without frustration, the complex structures and phase behavior are lost. All of the topics discussed in this thesis concern smectic liquid crystals. Liquid crystals are perhaps uniquely adept at manifesting frustrated phases. Their combination of periodicity in one or more dimensions allows ordered structures, yet their fluid nature in remaining dimensions allows creation of defects and extraordinarily complex structures in ways that a normal crystal could not tolerate. Liquid crystals contain a huge menagerie of frustrated phases and effects including the polarization modulated [2], vortex lattice [3], twist grain boundary [4], and blue [5] phases, as well as frustrated structures such as cholesteric or SmC* helix unwinding [6], defect lattices in thin films [7], and bend melted grain boundary defects [8], arising from boundary conditions and field effects. In this thesis, we study four liquid crystal systems that show unusual phase behavior or complex structures, deriving from the effects of frustration. Frustration, despite some human prejudices against the word, leaves nature all the more interesting and beautiful.
An IPMC-enabled bio-inspired bending/twisting fin for underwater applications
International Nuclear Information System (INIS)
Palmre, Viljar; Pugal, David; Kim, Sungjun; Kim, Kwang J; Hubbard, Joel J; Fleming, Maxwell; Leang, Kam K
2013-01-01
This paper discusses the design, fabrication, and characterization of an ionic polymer–metal composite (IPMC) actuator-based bio-inspired active fin capable of bending and twisting motion. It is pointed out that IPMC strip actuators are used in the simple cantilever configuration to create simple bending (flapping-like) motion for propulsion in underwater autonomous systems. However, the resulting motion is a simple 1D bending and performance is rather limited. To enable more complex deformation, such as the flapping (pitch and heaving) motion of real pectoral and caudal fish fins, a new approach which involves molding or integrating IPMC actuators into a soft boot material to create an active control surface (called a ‘fin’) is presented. The fin can be used to realize complex deformation depending on the orientation and placement of the actuators. In contrast to previously created IPMCs with patterned electrodes for the same purpose, the proposed design avoids (1) the more expensive process of electroless plating platinum all throughout the surface of the actuator and (2) the need for specially patterning the electrodes. Therefore, standard shaped IPMC actuators such as those with rectangular dimensions with varying thicknesses can be used. One unique advantage of the proposed structural design is that custom shaped fins and control surfaces can be easily created without special materials processing. The molding process is cost effective and does not require functionalizing or ‘activating’ the boot material similar to creating IPMCs. For a prototype fin (90 mm wide × 60 mm long × 1.5 mm thick), the measured maximum tip displacement was approximately 44 mm and the twist angle of the fin exceeded 10°. Lift and drag measurements in water where the prototype fin with an airfoil profile was dragged through water at a velocity of 21 cm s −1 showed that the lift and drag forces can be affected by controlling the IPMCs embedded into the fin structure
An IPMC-enabled bio-inspired bending/twisting fin for underwater applications
Palmre, Viljar; Hubbard, Joel J.; Fleming, Maxwell; Pugal, David; Kim, Sungjun; Kim, Kwang J.; Leang, Kam K.
2013-01-01
This paper discusses the design, fabrication, and characterization of an ionic polymer-metal composite (IPMC) actuator-based bio-inspired active fin capable of bending and twisting motion. It is pointed out that IPMC strip actuators are used in the simple cantilever configuration to create simple bending (flapping-like) motion for propulsion in underwater autonomous systems. However, the resulting motion is a simple 1D bending and performance is rather limited. To enable more complex deformation, such as the flapping (pitch and heaving) motion of real pectoral and caudal fish fins, a new approach which involves molding or integrating IPMC actuators into a soft boot material to create an active control surface (called a ‘fin’) is presented. The fin can be used to realize complex deformation depending on the orientation and placement of the actuators. In contrast to previously created IPMCs with patterned electrodes for the same purpose, the proposed design avoids (1) the more expensive process of electroless plating platinum all throughout the surface of the actuator and (2) the need for specially patterning the electrodes. Therefore, standard shaped IPMC actuators such as those with rectangular dimensions with varying thicknesses can be used. One unique advantage of the proposed structural design is that custom shaped fins and control surfaces can be easily created without special materials processing. The molding process is cost effective and does not require functionalizing or ‘activating’ the boot material similar to creating IPMCs. For a prototype fin (90 mm wide × 60 mm long × 1.5 mm thick), the measured maximum tip displacement was approximately 44 mm and the twist angle of the fin exceeded 10°. Lift and drag measurements in water where the prototype fin with an airfoil profile was dragged through water at a velocity of 21 cm s-1 showed that the lift and drag forces can be affected by controlling the IPMCs embedded into the fin structure. These
Mycoplasma insons sp. nov., a twisted mycoplasma from green iguanas (Iguana iguana).
May, Meghan; Ortiz, G Javier; Wendland, Lori D; Rotstein, David S; Relich, Ryan F; Balish, Mitchell F; Brown, Daniel R
2007-09-01
Mycoplasma insons sp. nov., first cultured from the choanae and tracheae of healthy green iguanas (Iguana iguana) from El Salvador, was readily distinguished from all previously described mollicutes and assigned to the Mycoplasma fastidiosum phylogenetic cluster by 16S rRNA gene sequence comparisons. Growth inhibition assays distinguished the isolates serologically from the other two members of that cluster. Many M. insons cells exhibit a remarkable twisted rod morphology despite lacking a cell wall. The organism is nonmotile, produces acid from glucose, but does not hydrolyze arginine, esculin, or urea. Mycoplasma insons 16S rRNA gene was also detected by PCR in packed blood cells from culture-negative iguanas. The type strain I17P1(T) has been deposited with the Mollicutes Collection at Purdue University and with the American Type Culture Collection (ATCC BAA-1435) in the USA. A limited number of cultures generated by the authors have also been deposited with the Culture Collection, University of Göteborg, in Sweden (CCUG 53461).
Modeling of twisted and coiled polymer (TCP) muscle based on phenomenological approach
Karami, Farzad; Tadesse, Yonas
2017-12-01
Twisted and coiled polymers (TCP) muscles are linear actuators that respond to change in temperature. Exploiting high negative coefficient of thermal expansion (CTE) and helical geometry give them a significant ability to change length in a limited temperature range. Several applications and experimental data of these materials have been demonstrated in the last few years. To use these actuators in robotics and control system applications, a mathematical model for predicting their behavior is essential. In this work, a practical and accurate phenomenological model for estimating the displacement of TCP muscles, as a function of the load as well as input electrical current, is proposed. The problem is broken down into two parts, i.e. modeling of the electro-thermal and then the thermo-elastic behavior of the muscles. For the first part, a differential equation, with changing electrical resistance term, is derived. Next, by using a temperature-dependent modulus of elasticity and CTE as well as taking the geometry of the muscles into account, an expression for displacement is derived. Experimental data for different loads and actuation current levels are used for verifying the model and investigating its accuracy. The result shows a good agreement between the simulation and experimental results for all loads.
HVP contributions to the muon (g−2 including QED corrections with twisted-mass fermions
Directory of Open Access Journals (Sweden)
Giusti Davide
2018-01-01
Full Text Available We present a lattice calculation of the Hadronic Vacuum Polarization (HVP contribution of the strange and charm quarks to the anomalous magnetic moment of the muon including leading-order electromagnetic (e.m. corrections. We employ the gauge configurations generated by the European Twisted Mass Collaboration (ETMC with Nf = 2+1 + 1 dynamical quarks at three values of the lattice spacing (a ≃ 0.062,0.082,0.089 fm with pion masses in the range Mπ ≃ 210 - 450 MeV. The strange and charm quark masses are tuned at their physical values. Neglecting discon-nected diagrams and after the extrapolations to the physical pion mass and to the continuum limit we obtain: aμsαem2=53.1±2.5⋅10−10,aμsαem3=−0.018±0.011⋅10−10 and aμcαem2=14.75±0.56⋅10−10,aμcαem3=−0.030±0.013⋅10−10 for the strange and charm contributions, respectively.!
QCD factorization beyond leading twist in exclusive processes: rhoT-meson production
International Nuclear Information System (INIS)
Wallon, S.; Anikin, I.; ); Ivanov, D.; Pire, B.; Szymanowski, L.
2009-01-01
Exclusive processes in hard electroproduction with asymptotic γ * p center of mass energy is one of the best place for understanding QCD in the perturbative Regge limit. The HERA experiment recently provided precise data for rho electroproduction, including all spin density matrix elements. From QCD, it is expected that such a process should factorize between a hard (calculable) coefficient function, and hadronic (P and ρ) matrix elements. Such a factorization is up to now only proven for a longitudinally polarized rho. Within the kt-factorization approach (valid at large s γ * p), we evaluate the impact factor of the transition γ * → ρT taking into account the twist 3 contributions. We show that a gauge invariant expression is obtained with the help of QCD equations of motion. More generally, relying on these equations and on the gauge invariance of the factorized amplitude, the non-perturbative Distribution Amplitudes can be reduced to a minimal set. This opens the way to a consistent treatment of factorization for exclusive processes with a transversally polarized vector meson. (author)
35 Hz shape memory alloy actuator with bending-twisting mode
Song, Sung-Hyuk; Lee, Jang-Yeob; Rodrigue, Hugo; Choi, Ik-Seong; Kang, Yeon June; Ahn, Sung-Hoon
2016-01-01
Shape Memory Alloy (SMA) materials are widely used as an actuating source for bending actuators due to their high power density. However, due to the slow actuation speed of SMAs, there are limitations in their range of possible applications. This paper proposes a smart soft composite (SSC) actuator capable of fast bending actuation with large deformations. To increase the actuation speed of SMA actuator, multiple thin SMA wires are used to increase the heat dissipation for faster cooling. The actuation characteristics of the actuator at different frequencies are measured with different actuator lengths and results show that resonance can be used to realize large deformations up to 35 Hz. The actuation characteristics of the actuator can be modified by changing the design of the layered reinforcement structure embedded in the actuator, thus the natural frequency and length of an actuator can be optimized for a specific actuation speed. A model is used to compare with the experimental results of actuators with different layered reinforcement structure designs. Also, a bend-twist coupled motion using an anisotropic layered reinforcement structure at a speed of 10 Hz is also realized. By increasing their range of actuation characteristics, the proposed actuator extends the range of application of SMA bending actuators. PMID:26892438
35 Hz shape memory alloy actuator with bending-twisting mode.
Song, Sung-Hyuk; Lee, Jang-Yeob; Rodrigue, Hugo; Choi, Ik-Seong; Kang, Yeon June; Ahn, Sung-Hoon
2016-02-19
Shape Memory Alloy (SMA) materials are widely used as an actuating source for bending actuators due to their high power density. However, due to the slow actuation speed of SMAs, there are limitations in their range of possible applications. This paper proposes a smart soft composite (SSC) actuator capable of fast bending actuation with large deformations. To increase the actuation speed of SMA actuator, multiple thin SMA wires are used to increase the heat dissipation for faster cooling. The actuation characteristics of the actuator at different frequencies are measured with different actuator lengths and results show that resonance can be used to realize large deformations up to 35 Hz. The actuation characteristics of the actuator can be modified by changing the design of the layered reinforcement structure embedded in the actuator, thus the natural frequency and length of an actuator can be optimized for a specific actuation speed. A model is used to compare with the experimental results of actuators with different layered reinforcement structure designs. Also, a bend-twist coupled motion using an anisotropic layered reinforcement structure at a speed of 10 Hz is also realized. By increasing their range of actuation characteristics, the proposed actuator extends the range of application of SMA bending actuators.
Clayburn, Nathan; Dreiling, Joan; McCarter, James; Ryan, Dominic; Poelker, Matt; Gay, Timothy
2012-06-01
GaAs photocathodes produce spin polarized electron beams when illuminated with circularly polarized light with photon energy approximately equal to the bandgap energy [1, 2]. A typical polarization value obtained with bulk GaAs and conventional circularly polarized light is 35%. This study investigated the spin polarization of electron beams emitted from GaAs illuminated with ``twisted light,'' an expression that describes a beam of light having orbital angular momentum (OAM). In the experiment, 790nm laser light was focused to a near diffraction-limited spot size on the surface of the GaAs photocathode to determine if OAM might couple to valence band electron spin mediated by the GaAs lattice. Our polarization measurements using a compact retarding-field micro-Mott polarimeter [3] have established an upper bound on the polarization of the emitted electron beam of 2.5%. [4pt] [1] D.T. Pierce, F. Meier, P. Zurcher, Appl. Phys. Lett. 26 670 (1975).[0pt] [2] C.K. Sinclair, et al., PRSTAB 10 023501 (2007).[0pt] [3] J.L. McCarter, M.L. Stutzman, K.W. Trantham, T.G. Anderson, A.M. Cook, and T.J. Gay Nucl. Instrum. and Meth. A (2010).
HVP contributions to the muon (g-2) including QED corrections with twisted-mass fermions
Giusti, Davide; Lubicz, Vittorio; Martinelli, Guido; Sanfilippo, Francesco; Simula, Silvano
2018-03-01
We present a lattice calculation of the Hadronic Vacuum Polarization (HVP) contribution of the strange and charm quarks to the anomalous magnetic moment of the muon including leading-order electromagnetic (e.m.) corrections. We employ the gauge configurations generated by the European Twisted Mass Collaboration (ETMC) with Nf = 2+1 + 1 dynamical quarks at three values of the lattice spacing (a ≃ 0.062,0.082,0.089 fm) with pion masses in the range Mπ ≃ 210 - 450 MeV. The strange and charm quark masses are tuned at their physical values. Neglecting discon-nected diagrams and after the extrapolations to the physical pion mass and to the continuum limit we obtain: aμs(αem2) = (53.1 ± 2.5 )×10-10, aμs(αem2) = (-0.018 ± 0.011)×10-10 and aμs(αem2) = (14.75±0.56)×10-10,aμs(αem2) = (-0.030±0.013)×10-10 for the strange and charm contributions, respectively.!
An estimate of higher twist at small xB and low Q2 based upon a saturation model
International Nuclear Information System (INIS)
Bartels, J.; Peters, K.
2000-03-01
We investigate the influence of higher twist corrections to deep inelastic structure functions in the low-Q 2 and small-x HERA region. We review the general features of the lowest-order QCD diagrams which contribute to twist-4 at small-x, in particular the sign structure of longitudinal and transverse structure functions which offers the possibility of strong cancellations in F 2 . For a numerical analysis we perform a twist analysis of the saturation model which has been very successful both in describing the structure function and the DIS diffractive cross section at HERA. As the main conclusion, twist 4 corrections are not small in F L or F T but in F 2 = F L + F T they almost cancel. We point out that F L analysis needs a large twist-4 correction. We also indicate the region of validity of the twist expansion. (orig.)
Particle image velocimetry measurements of 2-dimensional velocity field around twisted tape
Energy Technology Data Exchange (ETDEWEB)
Song, Min Seop; Park, So Hyun; Kim, Eung Soo, E-mail: kes7741@snu.ac.kr
2016-11-01
Highlights: • Measurements of the flow field in a pipe with twisted tape were conducted by particle image velocimetry (PIV). • A novel matching index of refraction technique utilizing 3D printing and oil mixture was adopted to make the test section transparent. • Undistorted particle images were clearly captured in the presence of twisted tape. • 2D flow field in the pipe with twisted tape revealed the characteristic two-peak velocity profile. - Abstract: Twisted tape is a passive component used to enhance heat exchange in various devices. It induces swirl flow that increases the mixing of fluid. Thus, ITER selected the twisted tape as one of the candidates for turbulence promoting in the divertor cooling. Previous study was mainly focused on the thermohydraulic performance of the twisted tape. As detailed data on the velocity field around the twisted tape was insufficient, flow visualization study was performed to provide fundamental data on velocity field. To visualize the flow in a complex structure, novel matching index of refraction technique was used with 3-D printing and mixture of anise and mineral oil. This technique enables the camera to capture undistorted particle image for velocity field measurement. Velocity fields at Reynolds number 1370–9591 for 3 different measurement plane were obtained through particle image velocimetry. The 2-dimensional averaged velocity field data were obtained from 177 pair of instantaneous velocity fields. It reveals the characteristic two-peak flow motion in axial direction. In addition, the normalized velocity profiles were converged with increase of Reynolds numbers. Finally, the uncertainty of the result data was analyzed.
Chirality-controlled spontaneous twisting of crystals due to thermal topochemical reaction.
Rai, Rishika; Krishnan, Baiju P; Sureshan, Kana M
2018-03-20
Crystals that show mechanical response against various stimuli are of great interest. These stimuli induce polymorphic transitions, isomerizations, or chemical reactions in the crystal and the strain generated between the daughter and parent domains is transcribed into mechanical response. We observed that the crystals of modified dipeptide LL (N 3 -l-Ala-l-Val-NHCH 2 C≡CH) undergo spontaneous twisting to form right-handed twisted crystals not only at room temperature but also at 0 °C over time. Using various spectroscopic techniques, we have established that the twisting is due to the spontaneous topochemical azide-alkyne cycloaddition (TAAC) reaction at room temperature or lower temperatures. The rate of twisting can be increased by heating, exploiting the faster kinetics of the TAAC reaction at higher temperatures. To address the role of molecular chirality in the direction of twisting the enantiomer of dipeptide LL, N 3 -d-Ala-d-Val-NHCH 2 C≡CH (DD), was synthesized and topochemical reactivity and mechanoresponse of its crystals were studied. We have found that dipeptide DD not only underwent TAAC reaction, giving 1,4-triazole-linked pseudopolypeptides of d-amino acids, but also underwent twisting with opposite handedness (left-handed twisting), establishing the role of molecular chirality in controlling the direction of mechanoresponse. This paper reports ( i ) a mechanical response due to a thermal reaction and ( ii ) a spontaneous mechanical response in crystals and ( iii ) explains the role of molecular chirality in the handedness of the macroscopic mechanical response.
PARTIAL ERUPTION OF A FILAMENT WITH TWISTING NON-UNIFORM FIELDS
International Nuclear Information System (INIS)
Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Xiang, Yongyuan; Cai, Yunfang; Liu, Weiwei
2015-01-01
The eruption of a filament in a kinklike fashion is often regarded as a signature of kink instability. However, the kink instability threshold for the filament’s magnetic structure is not widely understood. Using Hα observations from the New Vacuum Solar Telescope, we present a partial eruptive filament. During the eruption, the filament thread appeared to split from its middle and to break out in a kinklike fashion. In this period, the remaining filament material stayed below and erupted without the kinking motion later on. The coronal magnetic field lines associated with the filament are obtained from nonlinear force-free field extrapolations using the twelve-minute-cadence vector magnetograms of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory. We studied the extrapolated field lines passing through the magnetic dips which are in good agreement with the observed filament. The field lines are non-uniformly twisted and appear to be composed of two twisted flux ropes winding around each other. One of them has a higher twist than the other, and the flux rope with the higher twist has its dips aligned with the kinking eruptive thread at the beginning of its eruption. Before the eruption, moreover, the flux rope with the higher twist was found to expand with an approximately constant field twist. In addition, the helicity flux maps deduced from the HMI magnetograms show that some helicity is injected into the overlying magnetic arcade, but no significant helicity is injected into the flux ropes. Accordingly, we suggest that the highly twisted flux rope became kink unstable when the instability threshold declined with the expansion of the flux rope
Design and analysis of variable-twist tiltrotor blades using shape memory alloy hybrid composites
International Nuclear Information System (INIS)
Park, Jae-Sang; Kim, Seong-Hwan; Jung, Sung Nam; Lee, Myeong-Kyu
2011-01-01
The tiltrotor blade, or proprotor, acts as a rotor in the helicopter mode and as a propeller in the airplane mode. For a better performance, the proprotor should have different built-in twist distributions along the blade span, suitable for each operational mode. This paper proposes a new variable-twist proprotor concept that can adjust the built-in twist distribution for given flight modes. For a variable-twist control, the present proprotor adopts shape memory alloy hybrid composites (SMAHC) containing shape memory alloy (SMA) wires embedded in the composite matrix. The proprotor of the Korea Aerospace Research Institute (KARI) Smart Unmanned Aerial Vehicle (SUAV), which is based on the tiltrotor concept, is used as a baseline proprotor model. The cross-sectional properties of the variable-twist proprotor are designed to maintain the cross-sectional properties of the original proprotor as closely as possible. However, the torsion stiffness is significantly reduced to accommodate the variable-twist control. A nonlinear flexible multibody dynamic analysis is employed to investigate the dynamic characteristics of the proprotor such as natural frequency and damping in the whirl flutter mode, the blade structural loads in a transition flight and the rotor performance in hover. The numerical results show that the present proprotor is designed to have a strong similarity to the baseline proprotor in dynamic and load characteristics. It is demonstrated that the present proprotor concept could be used to improve the hover performance adaptively when the variable-twist control using the SMAHC is applied appropriately
Design and analysis of variable-twist tiltrotor blades using shape memory alloy hybrid composites
Park, Jae-Sang; Kim, Seong-Hwan; Jung, Sung Nam; Lee, Myeong-Kyu
2011-01-01
The tiltrotor blade, or proprotor, acts as a rotor in the helicopter mode and as a propeller in the airplane mode. For a better performance, the proprotor should have different built-in twist distributions along the blade span, suitable for each operational mode. This paper proposes a new variable-twist proprotor concept that can adjust the built-in twist distribution for given flight modes. For a variable-twist control, the present proprotor adopts shape memory alloy hybrid composites (SMAHC) containing shape memory alloy (SMA) wires embedded in the composite matrix. The proprotor of the Korea Aerospace Research Institute (KARI) Smart Unmanned Aerial Vehicle (SUAV), which is based on the tiltrotor concept, is used as a baseline proprotor model. The cross-sectional properties of the variable-twist proprotor are designed to maintain the cross-sectional properties of the original proprotor as closely as possible. However, the torsion stiffness is significantly reduced to accommodate the variable-twist control. A nonlinear flexible multibody dynamic analysis is employed to investigate the dynamic characteristics of the proprotor such as natural frequency and damping in the whirl flutter mode, the blade structural loads in a transition flight and the rotor performance in hover. The numerical results show that the present proprotor is designed to have a strong similarity to the baseline proprotor in dynamic and load characteristics. It is demonstrated that the present proprotor concept could be used to improve the hover performance adaptively when the variable-twist control using the SMAHC is applied appropriately.
miR-151-3p Targets TWIST1 to Repress Migration of Human Breast Cancer Cells.
Directory of Open Access Journals (Sweden)
Ting-Chih Yeh
Full Text Available TWIST1 is a highly conserved basic helix-loop-helix transcription factor that contributes to cancer metastasis by promoting an epithelial-mesenchymal transition and repressing E-cadherin gene expression in breast cancer. In this study, we explored the potential role of miR-151 in TWIST1 expression and cancer properties in human breast cancer cells. We found that the human TWIST1 3'UTR contains a potential binging site for miR-151-3p at the putative target sequence 5'-CAGUCUAG-3'. Using a TWIST1-3'UTR luciferase reporter assay, we demonstrated that the target sequence within the TWIST1 3'UTR is required for miR-151-3p regulation of TWIST1 expression. Moreover, we found that ectopic expression of miR-151-3p by infection with adenoviruses expressing miR-151 significantly decreased TWIST1 expression, migration and invasion, but did not affect cell growth and tumorsphere formation of human breast cancer cells. In addition, overexpression of the protein coding region without the 3'UTR of TWIST1 reversed the repression of cell migration by miR-151-3p. Furthermore, knockdown of miR-151-3p increased TWIST1 expression, reduced E-cadherin expression, and enhanced cell migration. In conclusion, these results suggest that miR-151-3p directly regulates TWIST1 expression by targeting the TWIST1 3'UTR and thus repressing the migration and invasion of human breast cancer cells by enhancing E-cadherin expression. Our findings add to accumulating evidence that microRNAs are involved in breast cancer progression by modulating TWIST1 expression.
Hadronic corrections to electroweak observables from twisted mass lattice QCD
International Nuclear Information System (INIS)
Pientka, Grit
2015-01-01
For several benchmark quantities investigated to detect signs for new physics beyond the standard model of elementary particle physics, lattice QCD currently constitutes the only ab initio approach available at small momentum transfers for the computation of non-perturbative hadronic contributions. Among those observables are the lepton anomalous magnetic moments and the running of the electroweak coupling constants. We compute the leading QCD contribution to the muon anomalous magnetic moment by performing lattice QCD calculations on ensembles incorporating N f =2+1+1 dynamical twisted mass fermions. Considering active up, down, strange, and charm quarks, admits for the first time a direct comparison of the lattice data for the muon anomaly with phenomenological results because both the latter as well as the experimentally obtained values are sensitive to the complete first two generations of quarks at the current level of precision. Recently, it has been noted that improved measurements of the electron and tau anomalous magnetic moments might also provide ways of detecting new physics contributions. Therefore, we also compute their leading QCD contributions, which simultaneously serve as cross-checks of the value obtained for the muon. Additionally, we utilise the obtained data to compute the leading hadronic contribution to the running of the fine structure constant, which enters all perturbative QED calculations. Furthermore, we show that even for the weak mixing angle the leading QCD contribution can be computed from this data. In this way, we identify a new prime observable in the search for new physics whose hadronic contributions can be obtained from lattice QCD. With the results obtained in this thesis, we are able to exclude unsuitable phenomenologically necessary flavour separations and thus directly assist the presently more precise phenomenological determinations of this eminent quantity.
Investigation of Shielding Properties of Yarns, Twisted with Metal Wire
Directory of Open Access Journals (Sweden)
Sandra VARNAITĖ-ŽURAVLIOVA
2014-04-01
Full Text Available The development level of the modern techniques and information technologies creates diverse nature electromagnetic fields and electric field accumulations in the human environment. Electrically conductive textiles that protect against electromagnetic waves and electric charge accumulations can be usable as protective covers for work in computer equipment rooms, measuring stands, air and gas filters and so on. One of the methods used in increase of electrical conductivity in textiles is the development of their specific structures (including the development of threads with the metal component. In this paper, unlike the currently used in the world conductive material production method, where different metal fibres are used as an additives to the main fibre composition in order to create a variety of fibres and yarns, a spun yarn with metal wire was prototyped as samples for this research and the parameters of protective properties of these samples were investigated (such as surface resistivity, vertical resistance, etc.. The protective and shielding properties of woven network with prototyped twisted electro conductive thread with a wire (metal wire diameter of 15 microns were investigated. During the investigation the influence of the following factors, such as conductive fibre composition, electrically conductive thread distribution frequency of the longitudinal and transverse direction, on the protective shielding properties of conductive network were analyzed. The research enabled the assessment of influence of electrically conductive fibre yarn composition and its distribution in the woven mesh on protective shielding properties. DOI: http://dx.doi.org/10.5755/j01.ms.20.1.2492
DEFF Research Database (Denmark)
Schneider, Uffe V; Géci, Imrich; Jøhnk, Nina
2011-01-01
-TINA molecules increased the melting point (Tm) of Watson-Crick based antiparallel DNA duplexes. The increase in Tm was greatest when the intercalators were placed at the 5' and 3' termini (preferable) or, if placed internally, for each half or whole helix turn. Terminally positioned TINA molecules improved......The sensitivity and specificity of clinical diagnostic assays using DNA hybridization techniques are limited by the dissociation of double-stranded DNA (dsDNA) antiparallel duplex helices. This situation can be improved by addition of DNA stabilizing molecules such as nucleic acid intercalators....... Here, we report the synthesis of a novel ortho-Twisted Intercalating Nucleic Acid (TINA) amidite utilizing the phosphoramidite approach, and examine the stabilizing effect of ortho- and para-TINA molecules in antiparallel DNA duplex formation. In a thermal stability assay, ortho- and para...
Twisted mass, overlap and Creutz fermions. Cut-off effects at tree-level of perturbation theory
International Nuclear Information System (INIS)
Cichy, K.; Kujawa, A.; Jansen, K.; Shindler, A.
2008-02-01
We study cutoff effects at tree-level of perturbation theory for maximally twisted mass Wilson, overlap and the recently proposed Creutz fermions. We demonstrate that all three kind of lattice fermions exhibit the expected O(a 2 ) scaling behaviour in the lattice spacing. In addition, the sizes of these cutoff effects are comparable for the three kinds of lattice fermions considered here. Furthermore, we analyze situations when twisted mass fermions are not exactly at maximal twist and when overlap fermions are studied in comparison to twisted mass fermions when the quark masses are not matched. (orig.)
Directory of Open Access Journals (Sweden)
Craig Armstrong
Full Text Available Increased left ventricular (LV twist and untwisting rate (LV twist mechanics are essential responses of the heart to exercise. However, previously a large variability in LV twist mechanics during exercise has been observed, which complicates the interpretation of results. This study aimed to determine some of the physiological sources of variability in LV twist mechanics during exercise. Sixteen healthy males (age: 22 ± 4 years, [Formula: see text]O2peak: 45.5 ± 6.9 ml∙kg-1∙min-1, range of individual anaerobic threshold (IAT: 32-69% of [Formula: see text]O2peak were assessed at rest and during exercise at: i the same relative exercise intensity, 40%peak, ii at 2% above IAT, and, iii at 40%peak with hypoxia (40%peak+HYP. LV volumes were not significantly different between exercise conditions (P > 0.05. However, the mean margin of error of LV twist was significantly lower (F2,47 = 2.08, P 0.05. Overall, LV twist mechanics were linearly related to rate pressure product. During exercise, the intra-individual variability of LV twist mechanics is smaller at the same relative exercise intensity compared with IAT. However, the absolute magnitude (degrees of LV twist mechanics appears to be associated with the prevailing rate pressure product. Exercise tests that evaluate LV twist mechanics should be standardised by relative exercise intensity and rate pressure product be taken into account when interpreting results.
Armstrong, Craig; Samuel, Jake; Yarlett, Andrew; Cooper, Stephen-Mark; Stembridge, Mike; Stöhr, Eric J.
2016-01-01
Increased left ventricular (LV) twist and untwisting rate (LV twist mechanics) are essential responses of the heart to exercise. However, previously a large variability in LV twist mechanics during exercise has been observed, which complicates the interpretation of results. This study aimed to determine some of the physiological sources of variability in LV twist mechanics during exercise. Sixteen healthy males (age: 22 ± 4 years, V˙O2peak: 45.5 ± 6.9 ml∙kg-1∙min-1, range of individual anaerobic threshold (IAT): 32–69% of V˙O2peak) were assessed at rest and during exercise at: i) the same relative exercise intensity, 40%peak, ii) at 2% above IAT, and, iii) at 40%peak with hypoxia (40%peak+HYP). LV volumes were not significantly different between exercise conditions (P > 0.05). However, the mean margin of error of LV twist was significantly lower (F2,47 = 2.08, P 0.05). Overall, LV twist mechanics were linearly related to rate pressure product. During exercise, the intra-individual variability of LV twist mechanics is smaller at the same relative exercise intensity compared with IAT. However, the absolute magnitude (degrees) of LV twist mechanics appears to be associated with the prevailing rate pressure product. Exercise tests that evaluate LV twist mechanics should be standardised by relative exercise intensity and rate pressure product be taken into account when interpreting results. PMID:27100099
High performance twisted and coiled soft actuator with spandex fiber for artificial muscles
Yang, Sang Yul; Cho, Kyeong Ho; Kim, Youngeun; Song, Min-Geun; Jung, Ho Sang; Yoo, Ji Wang; Moon, Hyungpil; Koo, Ja Choon; Nam, Jae-do; Ryeol Choi, Hyouk
2017-10-01
This paper reports the twisted and coiled soft actuator (abbreviated with STCA) with spandex fiber. The STCA exhibits higher actuation strain at lower temperature than the previous nylon twisted and coiled soft actuators (abbreviated with NTCAs). While NTCAs are fabricated using a twist-insertion process until coils are formed, a new method is developed to fabricate the STCA using the ultra-stretch of spandex, whereby the STCA is twisted again after the coil has been formed. A 6-gear-twist-insertion device that increases the stability and the fabrication speed is developed to fabricate the STCA. The superior performance exhibited by the STCA is due to the 14% contraction strain of the bare spandex (bare nylon: 4%) and the low spring constant of 0.0115 N mm-1. The maximum tensile actuation strain of STCA was 45% at 130 °C, and the maximum specific work was 1.523 kJ kg-1 at 130 °C. STCA could repeatedly actuate 100 times with a strain change of less than 0.4%.
Twist deformations leading to κ-Poincaré Hopf algebra and their application to physics
International Nuclear Information System (INIS)
Jurić, Tajron; Meljanac, Stjepan; Samsarov, Andjelo
2016-01-01
We consider two twist operators that lead to kappa-Poincaré Hopf algebra, the first being an Abelian one and the second corresponding to a light-like kappa-deformation of Poincaré algebra. The adventage of the second one is that it is expressed solely in terms of Poincaré generators. In contrast to this, the Abelian twist goes out of the boundaries of Poincaré algebra and runs into envelope of the general linear algebra. Some of the physical applications of these two different twist operators are considered. In particular, we use the Abelian twist to construct the statistics flip operator compatible with the action of deformed symmetry group. Furthermore, we use the light-like twist operator to define a star product and subsequently to formulate a free scalar field theory compatible with kappa-Poincaré Hopf algebra and appropriate for considering the interacting ϕ 4 scalar field model on kappa-deformed space. (paper)
Influence of pitch, twist, and taper on a blade`s performance loss due to roughness
Energy Technology Data Exchange (ETDEWEB)
Tangler, J.L. [National Renewable Energy Laboratory, Golden, Colorado (United States)
1997-08-01
The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade`s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor`s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP computer code with wind-tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord, non-twisted blade at several blade pitch angles. The results indicate that a constant-chord, non-twisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness. (au)
Energy Technology Data Exchange (ETDEWEB)
Guo, Y. [School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing 210023 (China); Pariat, E.; Moraitis, K. [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, F-92190 Meudon (France); Valori, G. [University College London, Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT (United Kingdom); Anfinogentov, S. [Institute of Solar-Terrestrial Physics SB RAS 664033, Irkutsk, P.O. box 291, Lermontov Street, 126a (Russian Federation); Chen, F. [Max-Plank-Institut für Sonnensystemforschung, D-37077 Göttingen (Germany); Georgoulis, M. K. [Research Center for Astronomy and Applied Mathematics of the Academy of Athens, 4 Soranou Efesiou Street, 11527 Athens (Greece); Liu, Y. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Thalmann, J. K. [Institute of Physics, Univeristy of Graz, Universitätsplatz 5/II, A-8010 Graz (Austria); Yang, S., E-mail: guoyang@nju.edu.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
2017-05-01
We study the writhe, twist, and magnetic helicity of different magnetic flux ropes, based on models of the solar coronal magnetic field structure. These include an analytical force-free Titov–Démoulin equilibrium solution, non-force-free magnetohydrodynamic simulations, and nonlinear force-free magnetic field models. The geometrical boundary of the magnetic flux rope is determined by the quasi-separatrix layer and the bottom surface, and the axis curve of the flux rope is determined by its overall orientation. The twist is computed by the Berger–Prior formula, which is suitable for arbitrary geometry and both force-free and non-force-free models. The magnetic helicity is estimated by the twist multiplied by the square of the axial magnetic flux. We compare the obtained values with those derived by a finite volume helicity estimation method. We find that the magnetic helicity obtained with the twist method agrees with the helicity carried by the purely current-carrying part of the field within uncertainties for most test cases. It is also found that the current-carrying part of the model field is relatively significant at the very location of the magnetic flux rope. This qualitatively explains the agreement between the magnetic helicity computed by the twist method and the helicity contributed purely by the current-carrying magnetic field.
Influence of pitch, twist, and taper on a blade`s performance loss due to roughness
Energy Technology Data Exchange (ETDEWEB)
Tangler, J.L. [National Renewable Energy Lab., Golden, CO (United States)
1996-12-31
The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade`s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor`s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP computer code with wind-tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord, non-twisted blade at several blade pitch angles. The results indicate that a constant-chord, non-twisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness. 8 refs., 6 figs.
Hover Testing of the NASA/Army/MIT Active Twist Rotor Prototype Blade
Wilbur, Matthew L.; Yeager, William T., Jr.; Wilkie, W. Keats; Cesnik, Carlos E. S.; Shin, Sangloon
2000-01-01
Helicopter rotor individual blade control promises to provide a mechanism for increased rotor performance and reduced rotorcraft vibrations and noise. Active material methods, such as piezoelectrically actuated trailing-edge flaps and strain-induced rotor blade twisting, provide a means of accomplishing individual blade control without the need for hydraulic power in the rotating system. Recent studies have indicated that controlled strain induced blade twisting can be attained using piezoelectric active fiber composite technology. In order to validate these findings experimentally, a cooperative effort between NASA Langley Research Center, the Army Research Laboratory, and the MIT Active Materials and Structures Laboratory has been developed. As a result of this collaboration an aeroelastically-scaled active-twist model rotor blade has been designed and fabricated for testing in the heavy gas environment of the Langley Transonic Dynamics Tunnel (TDT). The results of hover tests of the active-twist prototype blade are presented in this paper. Comparisons with applicable analytical predictions of active-twist frequency response in hovering flight are also presented.
Geometrically exact nonlinear analysis of pre-twisted composite rotor blades
Directory of Open Access Journals (Sweden)
Li'na SHANG
2018-02-01
Full Text Available Modeling of pre-twisted composite rotor blades is very complicated not only because of the geometric non-linearity, but also because of the cross-sectional warping and the transverse shear deformation caused by the anisotropic material properties. In this paper, the geometrically exact nonlinear modeling of a generalized Timoshenko beam with arbitrary cross-sectional shape, generally anisotropic material behavior and large deflections has been presented based on Hodges’ method. The concept of decomposition of rotation tensor was used to express the strain in the beam. The variational asymptotic method was used to determine the arbitrary warping of the beam cross section. The generalized Timoshenko strain energy was derived from the equilibrium equations and the second-order asymptotically correct strain energy. The geometrically exact nonlinear equations of motion were established by Hamilton’s principle. The established modeling was used for the static and dynamic analysis of pre-twisted composite rotor blades, and the analytical results were validated based on experimental data. The influences of the transverse shear deformation on the pre-twisted composite rotor blade were investigated. The results indicate that the influences of the transverse shear deformation on the static deformation and the natural frequencies of the pre-twisted composite rotor blade are related to the length to chord ratio of the blade. Keywords: Geometrically exact, Nonlinear, Pre-twisted composite blade, Transverse shear deformation, Variational asymptotic, Warping
Modeling and development of a twisting wing using inductively heated shape memory alloy actuators
Saunders, Robert N.; Hartl, Darren J.; Boyd, James G.; Lagoudas, Dimitris C.
2015-04-01
Wing twisting has been shown to improve aircraft flight performance. The potential benefits of a twisting wing are often outweighed by the mass of the system required to twist the wing. Shape memory alloy (SMA) actuators repeatedly demonstrate abilities and properties that are ideal for aerospace actuation systems. Recent advances have shown an SMA torsional actuator that can be manufactured and trained with the ability to generate large twisting deformations under substantial loading. The primary disadvantage of implementing large SMA actuators has been their slow actuation time compared to conventional actuators. However, inductive heating of an SMA actuator allows it to generate a full actuation cycle in just seconds rather than minutes while still . The aim of this work is to demonstrate an experimental wing being twisted to approximately 10 degrees by using an inductively heated SMA torsional actuator. This study also considers a 3-D electromagnetic thermo-mechanical model of the SMA-wing system and compare these results to experiments to demonstrate modeling capabilities.
Andelković, M.; Covaci, L.; Peeters, F. M.
2018-03-01
The in-plane dc conductivity of twisted bilayer graphene is calculated using an expansion of the real-space Kubo-Bastin conductivity in terms of Chebyshev polynomials. We investigate within a tight-binding approach the transport properties as a function of rotation angle, applied perpendicular electric field, and vacancy disorder. We find that for high-angle twists, the two layers are effectively decoupled, and the minimum conductivity at the Dirac point corresponds to double the value observed in monolayer graphene. This remains valid even in the presence of vacancies, hinting that chiral symmetry is still preserved. On the contrary, for low twist angles, the conductivity at the Dirac point depends on the twist angle and is not protected in the presence of disorder. Furthermore, for low angles and in the presence of an applied electric field, we find that the chiral boundary states emerging between AB and BA regions contribute to the dc conductivity, despite the appearance of localized states in the AA regions. The results agree qualitatively with recent transport experiments in low-angle twisted bilayer graphene.
Twisting null geodesic congruences and the Einstein-Maxwell equations
International Nuclear Information System (INIS)
Newman, Ezra T; Silva-Ortigoza, Gilberto
2006-01-01
In a recent article, we returned to the study of asymptotically flat solutions of the vacuum Einstein equations with a rather unconventional point of view. The essential observation in that work was that from a given asymptotically flat vacuum spacetime with a given Bondi shear, one can find a class of asymptotically shear-free (but, in general, twisting) null geodesic congruences where the class was uniquely given up to the arbitrary choice of a complex analytic 'worldline' in a four-dimensional complex space. By imitating certain terms in the Weyl tensor that are found in the algebraically special type II metrics, this complex worldline could be made unique and given-or assigned-the physical meaning as the complex centre of mass. Equations of motion for this case were found. The purpose of the present work is to extend those results to asymptotically flat solutions of the Einstein-Maxwell equations. Once again, in this case, we get a class of asymptotically shear-free null geodesic congruences depending on a complex worldline in the same four-dimensional complex space. However in this case there will be, in general, two distinct but uniquely chosen worldlines, one of which can be assigned as the complex centre of charge while the other could be called the complex centre of mass. Rather than investigating the situation where there are two distinct complex worldlines, we study instead the special degenerate case where the two worldlines coincide, i.e., where there is a single unique worldline. This mimics the case of algebraically special Einstein-Maxwell fields where the degenerate principle null vector of the Weyl tensor coincides with a Maxwell principle null vector. Again we obtain equations of motion for this worldline-but explicitly found here only in an approximation. Though there are ambiguities in assigning physical meaning to different terms it appears as if reliance on the Kerr and charged Kerr metrics and classical electromagnetic radiation theory helps
International Nuclear Information System (INIS)
Martovetsky, N.N.
2007-01-01
cryostability limit (by Stekly), or if there are enough losses to bring the temperature above the current sharing temperature taking into account limited heat capacity of the CICC, the strand will not recover, and the CICC will go normal. Conservatively, we will consider that if we find an instantaneous unstable situation, it is not acceptable. In presence of a transport current, the situation is sensitive to the direction of the strand twist, direction of the pulsed field and direction of the transport current. Recently, ITER decided to increase the twist pitch of the TF strands from 15 mm to 30 mm to improve the stability of the strands against the longitudinal field. In this report we will quantify the effects of this proposed change and perform a trade off study. The issue is that by increasing the twist pitch of the strands we not only increase the coupling losses in the transverse magnetic field, as expected in classical multifilamentary composite superconductors, but also increase the hysteresis losses in the strands with internal tin. In classical multifilamentary superconductors, twist pitch change should not cause an increase of the hysteresis losses in the transverse field. However the high Nb3Sn content internal tin strands develop transverse links, which couple the filaments into clusters. These links turn out to contribute a significant fraction to hysteresis losses [5]. If we project the results of [5] onto the ITER proposal to increase the twist pitch from 15 to 30 mm, we should expect the hysteresis losses to increase by a factor of two, which will likely disqualify strands with 30 mm twist pitch. This very strand twisted to 15 mm twist pitch would likely pass the ITER criteria. So, increasing the twist pitch has a very negative consequence and we need to make sure that it is absolutely necessary. Recently, A. Vostner (private communication) reported preliminary results on the losses in candidate TF strands. In agreement with what was reported in [5]; he found
Output Feedback Control of Electro-Hydraulic Cylinder Drives using the Twisting Algorithm
DEFF Research Database (Denmark)
Schmidt, Lasse; Andersen, Torben Ole; Pedersen, Henrik C.
2014-01-01
contributions in literature. This paper considers the twisting algorithm when applied directly for output feedback control, and with the design based on a reduced order model representation of an arbitrary valve driven hydraulic cylinder drive. The consequence of implementing such a controller with the well......This paper discusses the utilization of the so-called twisting algorithm when applied in output feedback position control schemes for electro-hydraulic cylinder drives. The twisting controller was the first second order sliding controller ever introduced, and can structure-wise be considered...... feedback controller may be successfully applied to hydraulic valve driven cylinder drives, with performance being on the level with a conventional surface based first order sliding mode controller....
Ellipticity and twisting of the isophotes of some bright galaxies in Virgo
International Nuclear Information System (INIS)
Barbon, R.; Benacchio, L.; Capaccioli, M.
1980-01-01
Ellipticity and twisting of the isophotes of four lenticular and seven elliptical galaxies in the Virgo cluster are presented as a sample of a more complete photometric investigation. This work has been motivated by the increasing importance of this kind of information for the understanding of the spatial structure of E galaxies. The calibrated plate material from the Loiano 1.52 meter and Tautenburg Schmidt telescopes has been digitized with a PDS microdensitometer and analysed by means of the Interactive Numerical Mapping Package (INMP). Ellipticity and orientation profiles are presented in a graphical form together with a preliminary discussion. A correlation has been found between ellipticity and twisting in barred lenticulars which might help in the understanding of some E galaxies such as NGC 4406 and NGC 4374. Twisting has been detected in all of the seven ellipticals of the sample
Performance Assessment in a Heat Exchanger Tube with Opposite/Parallel Wing Twisted Tapes
Directory of Open Access Journals (Sweden)
S. Eiamsa-ard
2015-02-01
Full Text Available The thermohydraulic performance in a tube containing a modified twisted tape with alternate-axes and wing arrangements is reported. This work aims to investigate the effects of wing arrangements (opposite (O and parallel (P wings at different wing shapes (triangle (Tri, rectangular (Rec, and trapezoidal (Tra wings and on the thermohydraulic performance characteristics. The obtained results show that wing twisted tapes with all wing shape arrangements (O-Tri/O-Rec/O-Tra/P-Tri/P-Rec/P-Tra give superior thermohydraulic performance and heat transfer rate to the typical twisted tape. In addition, the tapes with opposite wing arrangement of O-Tra, O-Rec, and O-Tri give superior thermohydraulic performances to those with parallel wing arrangement of P-Tra, P-Rec, and P-Tri around 2.7%, 3.5%, and 3.2%, respectively.
On the exchange of orbital angular momentum between twisted photons and atomic electrons
International Nuclear Information System (INIS)
Davis, Basil S; Kaplan, L; McGuire, J H
2013-01-01
We obtain an expression for the matrix element for scattering of a twisted (Laguerre–Gaussian profile) photon from a hydrogen atom. We consider photons incoming with an orbital angular momentum (OAM) of ℓħ, carried by a factor of e iℓϕ not present in a plane-wave or pure Gaussian profile beam. The nature of the transfer of +2ℓ units of OAM from the photon to the azimuthal atomic quantum number of the atom is investigated. We obtain simple formulas for these OAM flip transitions for elastic forward scattering of twisted photons when the photon wavelength λ is large compared with the atomic target size a, and small compared with the Rayleigh range z R , which characterizes the collimation length of the twisted photon beam. (paper)
Artificial blood-flow controlling effects of inhomogeneity of twisted magnetic fields
Nakagawa, Hidenori; Ohuchi, Mikio
2017-06-01
We developed a blood-flow controlling system using magnetic therapy for some types of nervous diseases. In our research, we utilized overlapped extremely low frequency (ELF) fields for the most effective blood-flow for the system. Results showed the possibility that the inhomogeneous region obtained by overlapping the fields at 50 Hz, namely, a desirably twisted field revealed a significant difference in induced electromotive forces at the insertion points of electrodes. In addition, ELF exposures with a high inhomogeneity of the twisted field at 50 Hz out of phase were more effective in generating an induced electromotive difference by approximately 31%, as contrasted with the difference generated by the exposure in phase. We expect that the increase of the inhomogeneity of the twisted field around a blood vessel can produce the most effective electromotive difference in the blood, and also moderately affect the excitable cells relating to the autonomic nervous system for an outstanding blood-flow control in vivo.
3-sphere fibrations: a tool for analyzing twisted materials in condensed matter
International Nuclear Information System (INIS)
Sadoc, J F; Charvolin, J
2009-01-01
Chiral molecules, when densely packed in soft condensed matter or biological materials, build organizations which are most often spontaneously twisted. The crystals of 'blue' phases formed by small mesogenic molecules demonstrate the structural importance of such a twist or torsion, and its presence was also recently observed in finite toroidal aggregates formed by long DNA molecules. The formation of these organizations is driven by the fact that compactness, which tends to align the molecules, enters into conflict with torsion, which tends to disrupt this alignment. This conflict of topological nature, or frustration, arises because of the flatness of the Euclidean space, but does not exist in the curved space of the 3-sphere where particular lines, its fibres, can be drawn which are parallel and nevertheless twisted. As these fibrations conciliate compactness and torsion, they can be used as geometrical templates for the analysis of organizations in the Euclidean space. We describe these fibrations, with a particular emphasis on their torsion.
Investigation of Structural Behavior due to Bend-Twist Couplings in Wind Turbine Blades
DEFF Research Database (Denmark)
Fedorov, Vladimir; Dimitrov, Nikolay Krasimirov; Berggreen, Christian
2010-01-01
for predicting the torsional response of the wind turbine blades with built-in bend-twist couplings. Additionally, a number of improved full-scale tests using an advanced bi-axial servo-hydraulic load control have been performed on a wind turbine blade section provided by Vestas Wind Systems A/S. In the present......One of the problematic issues concerning the design of future large composite wind turbine blades is the prediction of bend-twist couplings and torsion behaviour. The current work is a continuation of a previous work [1,2], and it examines different finite element modelling approaches...... of the blade cross section as the defining surface, off-setting the location of the shell elements according to the specified thickness. The experimental full-scale tests were carried out on an 8 m section of a 23 m wind turbine blade with specially implemented bend-twist coupling. The blade was tested under...
Quench Property of Twisted-Pair MgB$_2$ Superconducting Cables in Helium Gas
Spurrell, J; Falorio, I; Pelegrin, J; Ballarino, A; Yang, Y
2015-01-01
CERN's twisted-pair superconducting cable is a novel design which offers filament transposition, low cable inductance and is particularly suited for tape conductors such as 2G YBCO coated conductors, Ag-sheathed Bi2223 tapes and Ni/Monel-sheathed MgB2 tapes. A typical design of such twistedpair cables consists of multiple superconducting tapes intercalated with thin copper tapes as additional stabilizers. The copper tapes are typically not soldered to the superconducting tapes so that sufficient flexibility is retained for the twisting of the tape assembly. The electrical and thermal contacts between the copper and superconducting tapes are an important parameter for current sharing, cryogenic stability and quench propagation. Using an MgB2 twisted-pair cable assembly manufactured at CERN, we have carried out minimum quench energy (MQE) and propagation velocity (vp) measurements with point-like heat deposition localized within a tape. Furthermore, different contacts between the copper and superconductor aroun...
Optics of twisted nematic and supertwisted nematic liquid-crystal displays
Leenhouts, F.; Schadt, M.
1986-11-01
For the first time calculations of the off-state transmission of twisted nematic liquid-crystal displays (LCD's) are presented which exhibit twist angles greater than the conventional 90 °. The transmission has been calculated using a treatment introduced by Priestley. In addition, the CIE (Commission Internationale d'Eclairage) color coordinates were evaluated which, together with the brightness, determine the optical appearance of an LCD. The finite efficiency of the polarizers was taken into account. The results are compared with those obtained for conventional 90 ° twisted nematic LCD's. From the calculations follow the conditions required to obtain optimal contrast and steep electro-optical characteristics in 180 ° supertwisted LCD's designed for high information content applications.
Synthesis and structural determination of twisted MoS2 nanotubes
International Nuclear Information System (INIS)
Santiago, P.; Schabes-Retchkiman, P.; Ascencio, J.A.; Mendoza, D.; Perez-Alvarez, M.; Espinosa, A.; Reza-SanGerman, C.; Camacho-Bragado, G.A.; Jose-Yacaman, M.
2004-01-01
In the present work we report the synthesis of MoS 2 nanotubes with diameters greater than 10 nm using a template method. The length and properties of these nanotubes are a direct result of the preparation method. High-resolution transmission electron microscopy is used to study the structure of these highly curved entities. Molecular dynamics simulations of MoS 2 nanotubes reveal that one of the stable forms of the nanotubes is a twisted one. The twisting of the nanotubes produces a characteristic contrast in the images, which is also studied using simulation methods. The analysis of the local contrast close to the perpendicular orientation shows geometrical arrays of dots in domain-like structures, which are demonstrated to be a product of the atomic overlapping of irregular curvatures in the nanotubes. The configuration of some of the experimentally obtained nanotubes is demonstrated to be twisted with a behavior suggesting partial plasticity. (orig.)
Candy twists as an alternative to the glucola beverage in gestational diabetes mellitus screening.
Racusin, Diana A; Antony, Kathleen; Showalter, Lori; Sharma, Susan; Haymond, Morey; Aagaard, Kjersti M
2015-04-01
Screening for gestational diabetes mellitus commonly uses an oral glucose challenge test with a 50-g glucola beverage and subsequent venous puncture. However, up to 30% of pregnant women report significant side-effects, and the beverage is costly. We hypothesized that equivalent glucose loads could be achieved from a popular candy twist (Twizzlers; The Hershey Company, Hershey, PA) and tested it as cost-effective, tolerable alternative with a test of equivalency. The glucose equivalent of the 50-g glucola was calculated as 10 candy twists. We initially used a triple crossover design in nonpregnant patients whereby each subject served as her own control; this ensured the safety and equivalency of this load before using it among pregnant subjects. We then recruited pregnant women with an abnormal screening at 1 hour (glucose challenge test) in a double crossover design study. Subjects consumed 10 candy twists with a 1-hour venous blood glucose assessment. All subjects subsequently completed the confirmatory 3-hour glucose tolerance test. Sensitivity, specificity, positive predictive values, negative predictive values, false-referral rates, and detection rates were calculated. At ≥130 mg/dL, the sensitivity (100%) was the same for candy twists and glucola. However, the false-referral rate (82% vs 90%), positive predictive value (18% vs 10%), and detection rate (18% vs 10%) were improved for candy twists when compared with the 50-g glucola beverage. Our results indicate that strawberry-flavored candy twists are potentially an equally effective screening test, compared with the gold standard glucola beverage but lead to fewer false-positive screens and therefore could be a cost-effective alternative. Copyright © 2015 Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Popović Svetlana S.
2011-01-01
Full Text Available Membrane filtration has become one of the major technologies in the food industry. It is widely applied in the dairy industry, and it is mostly used for the concentration and fractionation of milk proteins and for the whey processing. Of all pressure driven membrane processes, ultrafiltration is the most widely used. The major disadvantage of pressure driven membrane processes is severe fouling of membrane during filtration particularly when the fluids containing proteins are processed. Fouling with proteins is complex phenomenon because it occurs at the membrane surface as well as in the pores of membrane, and depends on the operating conditions and on the interactions of proteins and membrane material. In order to reduce fouling of the membrane different techniques have been developed, and one of them relies on the changing of the hydrodynamic conditions in the membrane or module. In this study, influence of twisted tape turbulence promoters on the fouling reduction in cross-flow microfiltration of skim milk was investigated. Twisted tapes with tree characteristic ratios of helix element length to the tape diameter (aspect ratio were studied. It was shown that twisted tapes with different aspect ratios reduce fouling of membrane by a factor of three or more. The presence of twisted tape induces changes in the flow patterns from straight to helicoidally thus producing turbulence flow at the lower cross-flow rates. Turbulence intensification prevents accumulation of proteins at membrane surface enabling reduction in reversible fouling what results in the reduction of overall membrane fouling. The best performance was achieved using a twisted tape with the lowest aspect ratio of 1.0. This promoter reduces fouling seven times at low transmembrane pressure and low cross-flow velocity. The twisted tape with aspect ratio 1.0 induces the most intensive turbulence, the longest helicoidal flow path, and appearance of vortices near the membrane surfaces
Light polarization management via reflection from arrays of sub-wavelength metallic twisted bands
Nawrot, M.; Haberko, J.; Zinkiewicz, Ł.; Wasylczyk, P.
2017-12-01
With constant progress of nano- and microfabrication technologies, photolithography in particular, a number of sub-wavelength metallic structures have been demonstrated that can be used to manipulate light polarization. Numerical simulations of light propagation hint that helical twisted bands can have interesting polarization properties. We use three-dimensional two-photon photolithography (direct laser writing) to fabricate a few-micrometer-thick arrays of twisted bands and coat them uniformly with metal. We demonstrate that circular polarization can be generated from linear polarization upon reflection from such structures over a broad range of frequencies in the mid infrared.
Lie-deformed quantum Minkowski spaces from twists: Hopf-algebraic versus Hopf-algebroid approach
Lukierski, Jerzy; Meljanac, Daniel; Meljanac, Stjepan; Pikutić, Danijel; Woronowicz, Mariusz
2018-02-01
We consider new Abelian twists of Poincare algebra describing nonsymmetric generalization of the ones given in [1], which lead to the class of Lie-deformed quantum Minkowski spaces. We apply corresponding twist quantization in two ways: as generating quantum Poincare-Hopf algebra providing quantum Poincare symmetries, and by considering the quantization which provides Hopf algebroid describing class of quantum relativistic phase spaces with built-in quantum Poincare covariance. If we assume that Lorentz generators are orbital i.e. do not describe spin degrees of freedom, one can embed the considered generalized phase spaces into the ones describing the quantum-deformed Heisenberg algebras.
The quiver at the bottom of the twisted nilpotent cone on $\\mathbb P^1$
Rayan, Steven
2016-01-01
For the moduli space of Higgs bundles on a Riemann surface of positive genus, critical points of the natural Morse-Bott function lie along the nilpotent cone of the Hitchin fibration and are representations of $\\mbox{A}$-type quivers in a twisted category of holomorphic bundles. The critical points that globally minimize the function are representations of $\\mbox{A}_1$. For twisted Higgs bundles on the projective line, the quiver describing the bottom of the cone is more complicated. We deter...
Lattice study of D and D{sub s} meson form factors with twisted boundary conditions
Energy Technology Data Exchange (ETDEWEB)
Li, Ning; Wu, Ya-Jie [Xi' an Technological University, School of Science, Xi' an (China)
2017-03-15
We present results on the D and D{sub s} meson electromagnetic form factors using N{sub f} = 2 twisted mass Lattice Quantum Chromodynamics (LQCD) gauge configurations. In this simulation, to access spatial components of momenta that are different from the integer multiples of 2π/L, we apply twisted boundary conditions to compute corresponding correlation functions. Electromagnetic form factors with more small four-momentum transfer are determined, and further we fit the electromagnetic charge radius for D and D{sub s} mesons, respectively. (orig.)
Twisted Diff S sup 1 -action on loop groups and representations of the Virasoro algebra
Energy Technology Data Exchange (ETDEWEB)
Harnad, J [Montreal Univ., Quebec (Canada). Centre de Recherches Mathematiques (CRM); Kupershmidt, B A [Tennessee Univ., Tullahoma (USA). Space Inst.
1990-05-01
A modified Hamiltonian action of Diff S{sup 1} on the phase space LG{sup C}/G{sup C}, where LG is a loop group, is defined by twisting the usual action by a left translation in LG. This twisted action is shown to be generated by a nonequivariant moment map, thereby defining a classical Poisson bracket realization of a central extension of the Lie algebra diff{sub C} S{sup 1}. The resulting formula expresses the Diff S{sup 1} generators in terms of the left LG translation generators, giving a shifted modification of both the classical and quantum versions of the Sugawara formula. (orig.).
Effects of Head Size on the Performance of Twist-Off Bolts
Schnupp, Keith Otto
2003-01-01
This study examines a specific application of button-head type twist-off bolts. Currently, the Research Council on Structural Connections Specification (2000) removes the requirement for ASTM F436 washers (ASTM 2000a) under the bolt head of twist-off bolts where the head diameter equals or exceeds that of an ASTM F436 washer when oversized and slotted holes are used. The need for washers is also removed for A490 strength bolts used on steels with specified yield strengths less than 40 ksi p...
DEFF Research Database (Denmark)
Tahani, Mojtaba; Kavari, Ghazale; Masdari, Mehran
2017-01-01
This study is aimed to aerodynamically design a 1 mega-Watt horizontal axis wind turbine in order to obtain the maximum power coefficient by linearizing the chord and twist distributions. A new linearization method has been used for chord and twist distributions by crossing tangent line through...... the geometry of the blades determines the power generated by rotor, designing the blade is a very important issue. Herein, calculations are done for different types of airfoil families namely Risø-A1-21, Risø-A1-18, S809, S814 and Du 93-W-210. Hence, the effect of selecting different airfoil families is also...
Advanced Twisted Pair Cables for Distributed Local Area Networks in Intelligent Structure Systems
Semenov, Andrey
2018-03-01
The possibility of a significant increase in the length of cable communication channels of local area networks of automation and engineering support systems of buildings in the case of their implementation on balanced twisted pair cables is shown. Assuming a direct connection scheme and an effective speed of 100 Mbit/s, analytical relationships are obtained for the calculation of the maximum communication distance. The necessity of using in the linear part of such systems of twisted pair cables with U/UTP structure and interference parameters at the level of category 5e is grounded.
Multiperipheral ring dynamics and a definition of the complete twisted Reggeon loop
International Nuclear Information System (INIS)
Lucht, P.H.
1977-11-01
The t less than 0 multiperipheral formalism of Ciafaloni, DeTar, Misheloff, Mueller, Muzinich and Yesian is reviewed, extended, and applied to the ordered S-matrix whose ring amplitudes comprise the zeroth level of the topological expansion. Toller M-function notation is used throughout. The bootstrap and cylinder problems are formulated in terms of a well defined helicity pole propagator; a definition of the complete twisted Reggeon loop, which appears in the one-twist term of the cylinder, is given as a helicity pole expansion. Some consideration is given to the following subjects: diagonalization, naturality, threshold behavior, Regge cuts, and complex helicity
Indigenous unit for bending and twisting tests of ultra-thin films on a flexible substrate
D'souza, Slavia Deeksha; Hazarika, Pratim; Prakasarao, Ch Surya; Kovendhan, M.; Kumar, R. Arockia; Joseph, D. Paul
2018-04-01
An indigenous unit is designed to test the stability of thin films deposited on to a flexible substrate by inducing a required number of bending and twisting under specific conditions. The unit is designed using aluminum and automated by sending pulse width modulated signals to servo motors using ATmega328 microcontroller. We have tested the unit by imparting stress on to a commercial ITO film deposited on a PET substrate. After a definite number of bending and twisting cycles, the electrical and surface properties are studied and the results are discussed.
Pseudoscalar decay constants from N{sub f}=2+1+1 twisted mass lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Farchioni, Federico [Muenster Univ. (Germany). Inst. fuer Theoretische Physik; Herdoiza, Gregorio; Jansen, Karl; Nube, Andreas [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Petschlies, Marcus [Humboldt-Univ., Berlin (Germany). Inst. fuer Physik; Urbach, Carsten [Bonn Univ. (Germany). Helmholtz-Inst. fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics
2010-12-15
We present first results for the pseudoscalar decay constants f{sub K}, f{sub D} and f{sub D{sub S}} from lattice QCD with N{sub f} = 2 + 1 + 1 flavours of dynamical quarks. The lattice simulations have been performed by the European Twisted Mass collaboration (ETMC) using maximally twisted mass quarks. For the pseudoscalar decay constants we follow a mixed action approach by using so called Osterwalder-Seiler fermions in the valence sector for strange and charm quarks. The data for two values of the lattice spacing and several values of the up/down quark mass is analysed using chiral perturbation theory. (orig.)
A first look at maximally twisted mass lattice QCD calculations at the physical point
Energy Technology Data Exchange (ETDEWEB)
Abdel-Rehim, A. [The Cyprus Institute, Nicosia (Cyprus). CaSToRC; Boucaud, P. [Paris XI Univ., Orsay (France). Laboratoire de Physique Theorique; Carrasco, N. [Valencia-CSIC Univ. (Spain). Dept. de Fisica Teorica; IFIC, Valencia (Spain); and others
2013-11-15
In this contribution, a first look at simulations using maximally twisted mass Wilson fermions at the physical point is presented. A lattice action including clover and twisted mass terms is presented and the Monte Carlo histories of one run with two mass-degenerate flavours at a single lattice spacing are shown. Measurements from the light and heavy-light pseudoscalar sectors are compared to previous N{sub f}=2 results and their phenomenological values. Finally, the strategy for extending simulations to N{sub f}=2+1+1 is outlined.