HREM of general and twist grain boundaries.
Energy Technology Data Exchange (ETDEWEB)
Merkle, K. L.; Thompson, L. J.
1999-03-10
The observation of atomic-scale structures of grain boundaries (GBs) via axial illumination HREM has been largely restricted to tilt GBs, due to the requirement that the electron beam be parallel to a low-index zone axis on both sides of the interface. This condition can be fulfilled for all tilt GBs with disorientation about a low-index direction. The information obtained through HREM studies in many materials has brought important insights concerning the atomic-scale structure of such boundaries. However, it is well known that tilt GBs occupy only an infinitesimally small fraction of the 5-dimensional phase space which describes the macroscopic geometry of all GBs. Therefore, although tilt GBs are very important due to their low energy, it would be useful to also study twist GBs and general GBs that contain twist and tilt components.
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.
On the small angle twist sub-grain boundaries in Ti3AlC2
Zhang, Hui; Zhang, Chao; Hu, Tao; Zhan, Xun; Wang, Xiaohui; Zhou, Yanchun
2016-04-01
Tilt-dominated grain boundaries have been investigated in depth in the deformation of MAX phases. In stark contrast, another important type of grain boundaries, twist grain boundaries, have long been overlooked. Here, we report on the observation of small angle twist sub-grain boundaries in a typical MAX phase Ti3AlC2 compressed at 1200 °C, which comprise hexagonal screw dislocation networks formed by basal dislocation reactions. By first-principles investigations on atomic-scale deformation and general stacking fault energy landscapes, it is unequivocally demonstrated that the twist sub-grain boundaries are most likely located between Al and Ti4f (Ti located at the 4f Wyckoff sites of P63/mmc) layers, with breaking of the weakly bonded Al-Ti4f. The twist angle increases with the increase of deformation and is estimated to be around 0.5° for a deformation of 26%. This work may shed light on sub-grain boundaries of MAX phases, and provide fundamental information for future atomic-scale simulations.
Dislocation Nucleation on Grain Boundaries: Low Angle Twist and Asymmetric Tilt Boundaries
Directory of Open Access Journals (Sweden)
Erman Guleryuz
2016-07-01
Full Text Available We investigate the mechanisms of incipient plasticity at low angle twist and asymmetric tilt boundaries in fcc metals. To observe plasticity of grain boundaries independently of the bulk plasticity, we simulate nanoindentation of bicrystals. On the low angle twist boundaries, the intrinsic grain boundary (GB dislocation network deforms under load until a dislocation segment compatible with glide on a lattice slip plane is created. The half loops are then emitted into the bulk of the crystal. Asymmetric twist boundaries considered here did not produce bulk dislocations under load. Instead, the boundary with a low excess volume nucleated a mobile GB dislocation and additional GB defects. The GB sliding proceeded by motion of the mobile GB dislocation. The boundary with a high excess volume sheared elastically, while bulk-nucleated dislocations produced plastic relaxation.
Vacancy diffusion in CuΣ = 5[0 0 1] twist grain boundary
International Nuclear Information System (INIS)
Wen Yanni; Zhang Jianmin; Yang Wanmin; Xu Kewei
2009-01-01
Both the formation energies and the diffusive activation energy of a single vacancy migrating intra- and inter-layer in the first four atomic planes near CuΣ = 5[0 0 1] twist GB have been investigated by means of MD in conjunction with MAEAM. The effects of the GB on the vacancy formation and migration are only to the third layer. The vacancy is favorable to be formed on the un-coincident site in the first, second and third layers near the GB plane and this case is enhanced successively following the third, second and first layers. A single vacancy either on un-coincident site or on coincident site in the forth, third and second layers is favorable to migrate to un-coincident site (its first-nearest-neighbor) in its adjacent layer near the GB. But for the first layer, the favorable migration path of the vacancy on the un-coincident site is between un-coincident sites of the first layer or to its nearest-neighbor of the first layer in the rotating grain, which is not the case for the vacancy on the coincident site '1' that is migrated difficultly. So, there are collective tendency of the vacancy in the GB.
Energy Technology Data Exchange (ETDEWEB)
Pandey, M B [Physics Department, University of Allahabad, Allahabad-211 002 (India); Dhar, R [Physics Department, University of Allahabad, Allahabad-211 002 (India); Achalkumar, A S [Centre for Liquid Crystal Research, Jalahalli, Bangalore-560 103 (India); Yelamaggad, C V [Centre for Liquid Crystal Research, Jalahalli, Bangalore-560 103 (India)
2007-10-31
The investigated optically active dimeric compound, 4-n-undecyloxy-4{sup '}-(cholesteryloxycarbonyl-1-butyloxy)chalcone, shows wide temperature ranges of two twist grain boundary (TGB) phases, TGBA and TGBC*. Comprehensive dielectric studies have been carried out for this compound in the frequency range 1 Hz-10 MHz for different conditions of molecular anchoring. This compound shows negative dielectric anisotropy ({delta}{epsilon}'={epsilon}{sub parallel}'-{epsilon}{sub perpendicul=} a{sub r}'<0). Various electrical parameters, namely the dielectric permittivity, dielectric anisotropy, DC conductivity and activation energy, have been determined for these TGB phases. Weak relaxation processes have been detected in the TGBA and TGBC* phases, presumably due to amplitude (soft mode) and phase (Goldstone mode) fluctuations.
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...
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
International Nuclear Information System (INIS)
Young, G.A. Jr.; Najafabadi, R.; Strohmayer, W.; Baldrey, D.G.; Hamm, B.; Harris, J.; Sticht, J.; Wimmer, E.
2003-01-01
Atomistic modeling methods were employed to investigate the effects of impurity elements on the metallurgy, irradiation embrittlement, and environmentally assisted cracking of nickel-base alloys exposed to nuclear environments. Calculations were performed via ab initio atomistic modeling methods to ensure the accuracy and reliability of the results. A Griffith-type fracture criterion was used to quantitatively assess the effect of elements or element pairs on the grain boundary cohesive strength. In order of most embrittling to most strengthening, the elements are ranked as: He, Li, S, H, C, Zr, P, Fe, Mn, Nb, Cr, and B. Helium is strongly embrittling (-2.04 eV/atom lowering of the Griffith energy), phosphorus has little effect on the grain boundary (0.1 eV/atom), and boron offers appreciable strengthening (1.03 eV/atom increase in the Griffith energy). Calculations for pairs of elements (H-Li, H-B, H-C, H-P, and H-S) show little interaction on the grain boundary cohesive energy, so that for the conditions studied, linear superposition of elemental effects is a good approximation. These calculations help explain metallurgical effects (e.g. why boron can strengthen grain boundaries), irradiation embrittlement (e.g. how boron transmutation results in grain boundary embrittlement), as well as how grain boundary impurity elements can affect environmentally assisted cracking (i.e. low temperature crack propagation and stress corrosion cracking) of nickel-base alloys
Mikl, Joanne; Rye, David C
2016-02-01
The twisting somersault is a key skill in diving and gymnastics. The components of twist and somersault are defined with respect to anatomical axes, and combinations of multiples of half rotations of twist and somersault define specific twisting somersault skills. To achieve a twisting somersault skill twist must be continuous; otherwise oscillations in twist while somersaulting may be observed. The posture-dependent inertial properties of the athlete and the initial conditions determine if continuous or oscillating twist is observed. The paper derives equations for the amount of somersault required per half twist, or per twist oscillation, without making assumptions about the relative magnitudes of the moments of inertia. From these equations the skills achievable may be determined. The error associated with the common assumption that the medial and transverse principal moments of inertia are equal is explored. It is concluded that the error grows as the number of twists per somersault decreases, when the medial and transverse moments of inertia diverge, and when the longitudinal moment of inertia approaches either the medial or transverse moment of inertia. Inertial property data for an example athlete are used to illustrate the various rotational states that can occur. Copyright © 2015 Elsevier B.V. All rights reserved.
Mesoscale mechanics of twisting carbon nanotube yarns.
Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J
2015-03-12
Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle.
Meljanac, Daniel; Meljanac, Stjepan; Mignemi, Salvatore; Pikutić, Danijel; Štrajn, Rina
2018-03-01
We construct the twist operator for the Snyder space. Our starting point is a non-associative star product related to a Hermitian realisation of the noncommutative coordinates originally introduced by Snyder. The corresponding coproduct of momenta is non-coassociative. The twist is constructed using a general definition of the star product in terms of a bi-differential operator in the Hopf algebroid approach. The result is given by a closed analytical expression. We prove that this twist reproduces the correct coproducts of the momenta and the Lorentz generators. The twisted Poincaré symmetry is described by a non-associative Hopf algebra, while the twisted Lorentz symmetry is described by the undeformed Hopf algebra. This new twist might be important in the construction of different types of field theories on Snyder space.
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
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.)
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
Kronberg, Max; Soomro, Muhammad Afzal; Top, Jaap
2017-10-01
In this note we extend the theory of twists of elliptic curves as presented in various standard texts for characteristic not equal to two or three to the remaining characteristics. For this, we make explicit use of the correspondence between the twists and the Galois cohomology set H^1\\big({G}_{\\overline{K}/K}, \\operatorname{Aut}_{\\overline{K}}(E)\\big). The results are illustrated by examples.
Twisted radio waves and twisted thermodynamics.
Kish, Laszlo B; Nevels, Robert D
2013-01-01
We present and analyze a gedanken experiment and show that the assumption that an antenna operating at a single frequency can transmit more than two independent information channels to the far field violates the Second Law of Thermodynamics. Transmission of a large number of channels, each associated with an angular momenta 'twisted wave' mode, to the far field in free space is therefore not possible.
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...
Twisted Winged Endoparasitoids
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 9; Issue 10. Twisted Winged Endoparasitoids - An Enigma for Entomologists. Alpana Mazumdar. General Article Volume 9 Issue 10 October 2004 pp 19-24. Fulltext. Click here to view fulltext PDF. Permanent link:
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.
Energy Technology Data Exchange (ETDEWEB)
G.A. Young Jr.; R. Najafabadi; W. Strohmayer; D.G. Baldrey; B. Hamm; J. Harris; J. Sticht; E. Wimmer
2003-06-16
Atomistic modeling methods were employed to investigate the effects of impurity elements on the metallurgy, irradiation embrittlement, and environmentally assisted cracking of nickel-base alloys exposed to nuclear environments. Calculations were performed via ab initio atomistic modeling methods to ensure the accuracy and reliability of the results. A Griffith-type fracture criterion was used to quantitatively assess the effect of elements or element pairs on the grain boundary cohesive strength. In order of most embrittling to most strengthening, the elements are ranked as: He, Li, S, H, C, Zr, P, Fe, Mn, Nb, Cr, and B. Helium is strongly embrittling (-2.04 eV/atom lowering of the Griffith energy), phosphorus has little effect on the grain boundary (0.1 eV/atom), and boron offers appreciable strengthening (1.03 eV/atom increase in the Griffith energy). Calculations for pairs of elements (H-Li, H-B, H-C, H-P, and H-S) show little interaction on the grain boundary cohesive energy, so that for the conditions studied, linear superposition of elemental effects is a good approximation. These calculations help explain metallurgical effects (e.g. why boron can strengthen grain boundaries), irradiation embrittlement (e.g. how boron transmutation results in grain boundary embrittlement), as well as how grain boundary impurity elements can affect environmentally assisted cracking (i.e. low temperature crack propagation and stress corrosion cracking) of nickel-base alloys.
Aschieri, Paolo; Dimitrijević, Marija; Meyer, Frank; Schraml, Stefan; Wess, Julius
2006-10-01
Gauge theories on a space-time that is deformed by the Moyal-Weyl product are constructed by twisting the coproduct for gauge transformations. This way a deformed Leibniz rule is obtained, which is used to construct gauge invariant quantities. The connection will be enveloping algebra valued in a particular representation of the Lie algebra. This gives rise to additional fields, which couple only weakly via the deformation parameter θ and reduce in the commutative limit to free fields. Consistent field equations that lead to conservation laws are derived and some properties of such theories are discussed.
Twisting of paramodular vectors
Johnson-Leung, Jennifer; Roberts, Brooks
2013-01-01
Let $F$ be a non-archimedean local field of characteristic zero, let $(\\pi,V)$ be an irreducible, admissible representation of $\\GSp(4,F)$ with trivial central character, and let $\\chi$ be a quadratic character of $F^\\times$ with conductor $c(\\chi)>1$. We define a twisting operator $T_\\chi$ from paramodular vectors for $\\pi$ of level $n$ to paramodular vectors for $\\chi \\otimes \\pi$ of level $\\max(n+2c(\\chi),4c(\\chi))$, and prove that this operator has properties analogous to the well-known $...
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.)
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)
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.
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...
DEFF Research Database (Denmark)
Randrup, Thomas; Røgen, Peter
1996-01-01
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...
Twisting formula of epsilon factors
Indian Academy of Sciences (India)
For characters of a non-Archimedean local field we have explicit formula for epsilon factors. But in general, we do not have any generalized twisting formula of epsilon factors. In this paper, we give a generalized twisting formula of epsilon factorsvia local Jacobi sums.
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.
Twist1- and Twist2-haploinsufficiency results in reduced bone formation.
Directory of Open Access Journals (Sweden)
Yanyu Huang
Full Text Available Twist1 and Twist2 are highly homologous bHLH transcription factors that exhibit extensive highly overlapping expression profiles during development. While both proteins have been shown to inhibit osteogenesis, only Twist1 haploinsufficiency is associated with the premature synostosis of cranial sutures in mice and humans. On the other hand, biallelic Twist2 deficiency causes only a focal facial dermal dysplasia syndrome or additional cachexia and perinatal lethality in certain mouse strains. It is unclear how these proteins cooperate to synergistically regulate bone formation.Twist1 floxed mice (Twist1(f/f were bred with Twist2-Cre knock-in mice (Twist2(Cre/+ to generate Twist1 and Twist2 haploinsufficient mice (Twist1(f/+; Twist2(Cre/+. X-radiography, micro-CT scans, alcian blue/alizarin red staining, trap staining, BrdU labeling, immunohistochemistry, in situ hybridizations, real-time PCR and dual luciferase assay were employed to investigate the overall skeletal defects and the bone-associated molecular and cellular changes of Twist1(f/+;Twist2(Cre/+ mice.Twist1 and Twist2 haploinsufficient mice did not present with premature ossification and craniosynostosis; instead they displayed reduced bone formation, impaired proliferation and differentiation of osteoprogenitors. These mice exhibited decreased expressions of Fgf2 and Fgfr1-4 in bone, resulting in a down-regulation of FGF signaling. Furthermore, in vitro studies indicated that both Twist1 and Twist2 stimulated 4.9 kb Fgfr2 promoter activity in the presence of E12, a Twist binding partner.These data demonstrated that Twist1- and Twist2-haploinsufficiency caused reduced bone formation due to compromised FGF signaling.
"Oliver Twist": A Teacher's Guide.
Cashion, Carol; Fischer, Diana
This teacher's guide for public television's 3-part adaptation of Charles Dickens's "Oliver Twist" provides information that will help enrich students' viewing of the series, whether or not they read the novel. The guide includes a wide range of discussion and activity ideas; there is also a series Web site and a list of Web resources.…
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.
Twist buckling behavior of arteries.
Garcia, Justin R; Lamm, Shawn D; Han, Hai-Chao
2013-10-01
Arteries are often subjected to torsion due to body movement and surgical procedures. While it is essential that arteries remain stable and patent under twisting loads, the stability of arteries under torsion is poorly understood. The goal of this work was to experimentally investigate the buckling behavior of arteries under torsion and to determine the critical buckling torque, the critical buckling twist angle, and the buckling shape. Porcine common carotid arteries were slowly twisted in vitro until buckling occurred while subjected to a constant axial stretch ratio (1.1, 1.3, 1.5 (in vivo level) and 1.7) and lumen pressure (20, 40, 70 and 100 mmHg). Upon buckling, the arteries snapped to form a kink. For a group of six arteries, the axial stretch ratio significantly affected the critical buckling torque ([Formula: see text]) and the critical buckling twist angle ([Formula: see text]). Lumen pressure also significantly affected the critical buckling torque ([Formula: see text]) but had no significant effect on the critical twist angle ([Formula: see text]). Convex material constants for a Fung strain energy function were determined and fit well with the axial force, lumen pressure, and torque data measured pre-buckling. The material constants are valid for axial stretch ratios, lumen pressures, and rotation angles of 1.3-1.5, 20-100 mmHg, and 0-270[Formula: see text], respectively. The current study elucidates the buckling behavior of arteries under torsion and provides new insight into mechanical instability of blood vessels.
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
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.
Hydrogen bonds and twist in cellulose microfibrils.
Kannam, Sridhar Kumar; Oehme, Daniel P; Doblin, Monika S; Gidley, Michael J; Bacic, Antony; Downton, Matthew T
2017-11-01
There is increasing experimental and computational evidence that cellulose microfibrils can exist in a stable twisted form. In this study, atomistic molecular dynamics (MD) simulations are performed to investigate the importance of intrachain hydrogen bonds on the twist in cellulose microfibrils. We systematically enforce or block the formation of these intrachain hydrogen bonds by either constraining dihedral angles or manipulating charges. For the majority of simulations a consistent right handed twist is observed. The exceptions are two sets of simulations that block the O2-O6' intrachain hydrogen bond, where no consistent twist is observed in multiple independent simulations suggesting that the O2-O6' hydrogen bond can drive twist. However, in a further simulation where exocyclic group rotation is also blocked, right-handed twist still develops suggesting that intrachain hydrogen bonds are not necessary to drive twist in cellulose microfibrils. Copyright © 2017 Elsevier Ltd. All rights reserved.
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)
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
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.
Large N reduction on a twisted torus
International Nuclear Information System (INIS)
Gonzalez-Arroyo, A.; Narayanan, R.; Neuberger, H.
2005-01-01
We consider SU(N) lattice gauge theory at infinite N defined on a torus with a CP invariant twist. Massless fermions are incorporated in an elegant way, while keeping them quenched. We present some numerical results which suggest that twisting can make numerical simulations of planar QCD more efficient
Energetics Underlying Twist Polymorphisms in Amyloid Fibrils
Periole, Xavier; Huber, Thomas; Bonito-Oliva, Alessandra; Aberg, Karina C; van der Wel, Patrick C A; Sakmar, Thomas P; Marrink, Siewert J
2018-01-01
Amyloid fibrils are highly ordered protein aggregates associated with more than 40 human diseases. The exact conditions in which the fibrils are grown determine many types of reported fibril polymorphism, including different twist patterns. Twist-based polymorphs display unique mechanical properties
Twist buckling of veins under torsional loading.
Garcia, Justin R; Sanyal, Arnav; Fatemifar, Fatemeh; Mottahedi, Mohammad; Han, Hai-Chao
2017-06-14
Veins are often subjected to torsion and twisted veins can hinder and disrupt normal blood flow but their mechanical behavior under torsion is poorly understood. The objective of this study was to investigate the twist deformation and buckling behavior of veins under torsion. Twist buckling tests were performed on porcine internal jugular veins (IJVs) and human great saphenous veins (GSVs) at various axial stretch ratio and lumen pressure conditions to determine their critical buckling torques and critical buckling twist angles. The mechanical behavior under torsion was characterized using a two-fiber strain energy density function and the buckling behavior was then simulated using finite element analysis. Our results demonstrated that twist buckling occurred in all veins under excessive torque characterized by a sudden kink formation. The critical buckling torque increased significantly with increasing lumen pressure for both porcine IJV and human GSV. But lumen pressure and axial stretch had little effect on the critical twist angle. The human GSVs are stiffer than the porcine IJVs. Finite element simulations captured the buckling behavior for individual veins under simultaneous extension, inflation, and torsion with strong correlation between predicted critical buckling torques and experimental data (R 2 =0.96). We conclude that veins can buckle under torsion loading and the lumen pressure significantly affects the critical buckling torque. These results improve our understanding of vein twist behavior and help identify key factors associated in the formation of twisted veins. Copyright © 2017 Elsevier Ltd. All rights reserved.
Folded supersymmetry with a twist
Energy Technology Data Exchange (ETDEWEB)
Cohen, Timothy [Department of Physics, Princeton University,Princeton, NJ 08544 (United States); School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Institute of Theoretical Science, University of Oregon,Eugene, OR 97403 (United States); Craig, Nathaniel [Department of Physics, University of California,Santa Barbara, CA 93106 (United States); Lou, Hou Keong [Department of Physics, Princeton University,Princeton, NJ 08544 (United States); Pinner, David [Princeton Center for Theoretical Science, Princeton University,Princeton, NJ 08544 (United States)
2016-03-30
Folded supersymmetry (f-SUSY) stabilizes the weak scale against radiative corrections from the top sector via scalar partners whose gauge quantum numbers differ from their Standard Model counterparts. This non-trivial pairing of states can be realized in extra-dimensional theories with appropriate supersymmetry-breaking boundary conditions. We present a class of calculable f-SUSY models that are parametrized by a non-trivial twist in 5D boundary conditions and can accommodate the observed Higgs mass and couplings. Although the distinctive phenomenology associated with the novel folded states should provide strong evidence for this mechanism, the most stringent constraints are currently placed by conventional supersymmetry searches. These models remain minimally fine-tuned in light of LHC8 data and provide a range of both standard and exotic signatures accessible at LHC13.
International Nuclear Information System (INIS)
Leitch-Devlin, M.A.; Millar, T.J.; Williams, D.A.
1976-01-01
Infrared observations of the Orion nebula have been interpreted by Rowan-Robinson (1975) to imply the existence of 'giant' grains, radius approximately 10 -2 cm, throughout a volume about a parsec in diameter. Although Rowan-Robinson's model of the nebula has been criticized and the presence of such grains in Orion is disputed, the proposition is accepted, that they exist, and in this paper situations in which giant grains could arise are examined. It is found that, while a giant-grain component to the interstellar grain density may exist, it is difficult to understand how giant grains arise to the extent apparently required by the Orion nebula model. (Auth.)
International Nuclear Information System (INIS)
Kung, H.; Sass, S.L.
1992-01-01
This paper discusses the dislocation structure of small angle tilt and twist boundaries in ordered Ni 3 Al, with and without boron, investigated using transmission electron microscopy. Dislocation with Burgers vectors that correspond to anti-phase boundary (APB)-coupled superpartials were found in small angle twist boundaries in both boron-free and boron-doped Ni 3 Al, and a small angle tilt boundary in boron-doped Ni 3 Al. The boundary structures are in agreement with theoretical models proposed by Marcinkowski and co-workers. The APB energy determined from the dissociation of the grain boundary dislocations was lower than values reported for isolated APBs in Ni 3 Al. For small angle twist boundaries the presence of boron reduced the APB energy at the interface until it approached zero. This is consistent with the structure of these boundaries containing small regions of increased compositional disorder in the first atomic plane next to the interface
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 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.
Spintronics: A new twist in electronics
Indian Academy of Sciences (India)
BIPUL PAL
Semiconductor Nanostructures. Ultrafast Laser Spectroscopy. Spintronics: A new twist in electronics. Bipul Pal. Indian Institute of Science Education & Research – Kolkata. 02/07/09. 1st Platinum Jubilee Meeting of the Indian Academy of Sciences ...
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....
Deformation bands in ⟨120⟩ grains in coarse-grained aluminium
DEFF Research Database (Denmark)
Bilde-Sørensen, Jørgen
1986-01-01
](111) and (a/2)[011](111), allowing for glide only, are tilt boundaries with a normal [001] and a rotation axis along [110] and twist boundaries with a normal [100] and a rotation axis along [100]. A consideration of the boundary energies indicates that the twist boundary has a lower energy than the tilt...... to [001], the boundaries between the bands were parallel to [010] and the neighbouring bands were rotated around [100] with respect to one another. Two slip systems in a critical relationship are equally stressed with a Schmid factor of 0.49 in grains with a [120] orientation, namely (a/2...
Solute segregation at 46.89.sup.o./sup. (111) twist boundary of a phosphorus doped Fe-2.3%V alloy
Czech Academy of Sciences Publication Activity Database
Lejček, Pavel; Pokluda, J.; Šandera, P.; Horníková, J.; Jenko, M.
2012-01-01
Roč. 606, 3-4 (2012), s. 258-262 ISSN 0039-6028 R&D Projects: GA ČR GA106/08/0369 Institutional research plan: CEZ:AV0Z10100520 Keywords : grain boundary segregation * phosphorus * Fe-V-alloy * twist grain boundary * AES quantification * grain boundary classification Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.838, year: 2012
TWIST is Expressed in Human Gliomas, Promotes Invasion
Directory of Open Access Journals (Sweden)
Maria C. Elias
2005-09-01
Full Text Available TWIST is a basic helix-loop-helix (bHLH transcription factor that regulates mesodermal development, promotes tumor cell metastasis, and, in response to cytotoxic stress, enhances cell survival. Our screen for bHLH gene expression in rat C6 glioma revealed TWIST. To delineate a possible oncogenic role for TWIST in the human central nervous system (CNS, we analyzed TWIST message, protein expression in gliomas, normal brain. TWIST was detected in the large majority of human glioma-derived cell lines, human gliomas examined. Increased TWIST mRNA levels were associated with the highest grade gliomas, increased TWIST expression accompanied transition from low grade to high grade in vivo, suggesting a role for TWIST in promoting malignant progression. In accord, elevated TWIST mRNA abundance preceded the spontaneous malignant transformation of cultured mouse astrocytes hemizygous for p53. Overexpression of TWIST protein in a human glioma cell line significantly enhanced tumor cell invasion, a hallmark of high-grade gliomas. These findings support roles for TWIST both in early glial tumorigenesis, subsequent malignant progression. TWIST was also expressed in embryonic, fetal human brain, in neurons, but not glia, of mature brain, indicating that, in gliomas, TWIST may promote the functions also critical for CNS development or normal neuronal physiology.
Analysis of gun barrel rifling twist
Sun, Jia; Chen, Guangsong; Qian, Linfang; Liu, Taisu
2017-05-01
Aiming at the problem of gun barrel rifling twist, the constraint relation between rifling and projectile is investigated. The constraint model of rifling and projectile is established and the geometric relation between the twist and the motion of projectile is analyzed. Based on the constraint model, according to the rotating band that is fired, the stress and the motion law of the rotating band in bore are analyzed. The effects to rotating band (double rotating band or wide driving band) caused by different rifling (rib rifling, increasing rifling and combined rifling) are also investigated. The model is demonstrated by several examples. The results of numerical examples and the constraint mode show that the uncertainty factors will be brought in the increasing rifling and combined rifling during the projectile move in the bore. According to the amplitude and the strength of the twist acting on rotating band, the steady property of rotational motion of the projectile, the rib rifling is a better choose.
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.
On the Symmetric Properties for the Generalized Twisted Bernoulli Polynomials
Directory of Open Access Journals (Sweden)
Kim Taekyun
2009-01-01
Full Text Available We study the symmetry for the generalized twisted Bernoulli polynomials and numbers. We give some interesting identities of the power sums and the generalized twisted Bernoulli polynomials using the symmetric properties for the -adic invariant integral.
Genetic Analysis and Mapping of TWH Gene in Rice Twisted Hull Mutant
Directory of Open Access Journals (Sweden)
Jin-bo LI
2009-03-01
Full Text Available A mutant with twisted hulls was found in a breeding population of rice (Oryza sativa L.. The mutant shows less grain weight and inferior grain quality in addition to twisted hulls. Genetic analysis indicated that the phenotype of mutant was controlled by a single recessive gene (temporarily designated as TWH. To map the TWH gene, an F2 population was generated by crossing the twh mutant to R725, an indica rice variety with normal hulls. For bulked segregant analysis, the bulk of mutant plants was prepared by mixing equal amount of plant tissue from 10 twisted-hull plants and the bulk of normal plants was obtained by pooling equal amount tissue of 10 normal-hull plants. Two hundred and seven pairs of simple sequence repeat (SSR primers, which are distributed on 12 rice chromosomes, were used for polymorphism analysis of the parents and the two bulks. The TWH locus was initially mapped close to the SSR marker RM526 on chromosome 2. Therefore, further mapping was performed using 50 pairs of SSR primers around the marker RM526. The TWH was delimited between the SSR markers RM14128 and RM208 on the long arm of chromosome 2 at the genetic distances of 1.4 cM and 2.7 cM, respectively. These results provide the foundation for further fine mapping, cloning and functional analysis of the TWH gene.
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.
Twisted surfaces in the Pseudo-Galilean space
Directory of Open Access Journals (Sweden)
Ahmet Kazan
2017-10-01
Full Text Available In this paper, we construct the twisted surfaces according to the supporting plane and type of rotations in pseudo-Galilean space G13. Also, we find the Gaussian curvatures and mean curvatures of the different types of these twisted surfaces and draw some figures for these twisted surfaces.
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.
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
DeMarco, Frederick
2010-01-01
This article describes an art activity on self-portraiture inspired by artist Tim Hawkinson. Hawkinson created a sculpture titled "Emoter" in which his face, moved by motors, twisted and contorted based on random signals from a TV. This art activity incorporates technology into the art room, brings the work of practicing artists alive, and is a…
Twisted holomorphic forms on generalized flag varieties
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
As a corollary of Theorem 1 and Proposition 2, we get the following vanishing theorem: ..... easily what the maximum positive value is which can occur in (µ, α∨ ... Twisted holomorphic forms on generalized flag varieties. 129. The following observation will be useful in writing down the conditions stated in the proposition.
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...
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)
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.
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.
MAGNETIC FIELD TWISTING BY INTERGRANULAR DOWNDRAFTS
Energy Technology Data Exchange (ETDEWEB)
Taroyan, Youra; Williams, Thomas [Department of Physics, IMPACS, Aberystwyth University, Aberystwyth (United Kingdom)
2016-10-01
The interaction of an intergranular downdraft with an embedded vertical magnetic field is examined. It is demonstrated that the downdraft may couple to small magnetic twists leading to an instability. The descending plasma exponentially amplifies the magnetic twists when it decelerates with depth due to increasing density. Most efficient amplification is found in the vicinity of the level, where the kinetic energy density of the downdraft reaches equipartition with the magnetic energy density. Continual extraction of energy from the decelerating plasma and growth in the total azimuthal energy occurs as a consequence of the wave-flow coupling along the downdraft. The presented mechanism may drive vortices and torsional motions that have been detected between granules and in simulations of magnetoconvection.
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...
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.
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.
Energy Technology Data Exchange (ETDEWEB)
Yuan, Xiaokun, E-mail: yuanxiaokun@bjut.edu.cn
2013-12-05
Highlights: •GBCDs of two kinds of CSL boundaries in cemented carbides are examined. •Carbide mean grain size is determinant in controlling the populations of CSL boundaries. •Rapid decrease of sigma2 boundaries occurs at higher speed than the coarsening of carbide grains. -- Abstract: The grain boundary character distributions of sigma2 and sigma13 boundaries were investigated in cemented carbide samples with different carbide grain sizes. Samples were prepared with average carbide grain sizes of about 0.5 μm, 1 μm and 2 μm, respectively. The electron backscattered diffraction measurements show that with the increase of the carbide grain size, populations of both sigma2 and sigma13 boundaries decrease; in the meantime, the sigma2 twist and sigma13 twist boundaries keep as the most common boundary types. The results suggest that the carbide grain size could be determinant in controlling the populations of coincidence site lattice boundaries in WC-Co composites.
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.
Twisted rudder for reducing fuel-oil consumption
Directory of Open Access Journals (Sweden)
Kim Jung-Hun
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
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.
Twisted rudder for reducing fuel-oil consumption
Kim, Jung-Hun; Choi, Jung-Eun; Choi, Bong-Jun; Chung, Seok-Ho
2014-09-01
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.)
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.
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.
Computational design of an automotive twist beam
Directory of Open Access Journals (Sweden)
Benki Aalae
2016-07-01
Full Text Available In recent years, the automotive industry has known a remarkable development in order to satisfy the customer requirements. In this paper, we will study one of the components of the automotive which is the twist beam. The study is focused on the multicriteria design of the automotive twist beam undergoing linear elastic deformation (Hooke׳s law. Indeed, for the design of this automotive part, there are some criteria to be considered as the rigidity (stiffness and the resistance to fatigue. Those two criteria are known to be conflicting, therefore, our aim is to identify the Pareto front of this problem. To do this, we used a Normal Boundary Intersection (NBI algorithm coupling with a radial basis function (RBF metamodel in order to reduce the high calculation time needed for solving the multicriteria design problem. Otherwise, we used the free form deformation (FFD technique for the generation of the 3D shapes of the automotive part studied during the optimization process.
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)
Needleless electrospinning with twisted wire spinneret
International Nuclear Information System (INIS)
Holopainen, Jani; Penttinen, Toni; Santala, Eero; Ritala, Mikko
2015-01-01
A needleless electrospinning setup named ‘Needleless Twisted Wire Electrospinning’ was developed. The polymer solution is electrospun from the surface of a twisted wire set to a high voltage and collected on a cylindrical collector around the wire. Multiple Taylor cones are simultaneously self-formed on the downward flowing solution. The system is robust and simple with no moving parts aside from the syringe pump used to transport the solution to the top of the wire. The structure and process parameters of the setup and the results on the preparation of polyvinyl pyrrolidone (PVP), hydroxyapatite (HA) and bioglass fibers with the setup are presented. PVP fiber sheets with areas of 40 × 120 cm 2 and masses up to 1.15 g were prepared. High production rates of 5.23 g h −1 and 1.40 g h −1 were achieved for PVP and HA respectively. The major limiting factor of the setup is drying of the polymer solution on the wire during the electrospinning process which will eventually force to interrupt the process for cleaning of the wire. Possible solutions to this problem and other ways to develop the setup are discussed. The presented system provides a simple way to increase the production rate and area of fiber sheet as compared with the conventional needle electrospinning. (paper)
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...
Design optimization of a twist compliant mechanism with nonlinear stiffness
Tummala, Y.; Frecker, M. I.; Wissa, A. A.; Hubbard, J. E., Jr.
2014-10-01
A contact-aided compliant mechanism called a twist compliant mechanism (TCM) is presented in this paper. This mechanism has nonlinear stiffness when it is twisted in both directions along its axis. The inner core of the mechanism is primarily responsible for its flexibility in one twisting direction. The contact surfaces of the cross-members and compliant sectors are primarily responsible for its high stiffness in the opposite direction. A desired twist angle in a given direction can be achieved by tailoring the stiffness of a TCM. The stiffness of a compliant twist mechanism can be tailored by varying thickness of its cross-members, thickness of the core and thickness of its sectors. A multi-objective optimization problem with three objective functions is proposed in this paper, and used to design an optimal TCM with desired twist angle. The objective functions are to minimize the mass and maximum von-Mises stress observed, while minimizing or maximizing the twist angles under specific loading conditions. The multi-objective optimization problem proposed in this paper is solved for an ornithopter flight research platform as a case study, with the goal of using the TCM to achieve passive twisting of the wing during upstroke, while keeping the wing fully extended and rigid during the downstroke. Prototype TCMs have been fabricated using 3D printing and tested. Testing results are also presented in this paper.
Design optimization of a twist compliant mechanism with nonlinear stiffness
International Nuclear Information System (INIS)
Tummala, Y; Frecker, M I; Wissa, A A; Hubbard, J E Jr
2014-01-01
A contact-aided compliant mechanism called a twist compliant mechanism (TCM) is presented in this paper. This mechanism has nonlinear stiffness when it is twisted in both directions along its axis. The inner core of the mechanism is primarily responsible for its flexibility in one twisting direction. The contact surfaces of the cross-members and compliant sectors are primarily responsible for its high stiffness in the opposite direction. A desired twist angle in a given direction can be achieved by tailoring the stiffness of a TCM. The stiffness of a compliant twist mechanism can be tailored by varying thickness of its cross-members, thickness of the core and thickness of its sectors. A multi-objective optimization problem with three objective functions is proposed in this paper, and used to design an optimal TCM with desired twist angle. The objective functions are to minimize the mass and maximum von-Mises stress observed, while minimizing or maximizing the twist angles under specific loading conditions. The multi-objective optimization problem proposed in this paper is solved for an ornithopter flight research platform as a case study, with the goal of using the TCM to achieve passive twisting of the wing during upstroke, while keeping the wing fully extended and rigid during the downstroke. Prototype TCMs have been fabricated using 3D printing and tested. Testing results are also presented in this paper. (paper)
Two new twisted helical nickel (II) and cobalt (III) octahedral ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 6. Two new twisted helical nickel(II) and cobalt(III) octahedral monomer complexes: Synthesis and structural characterization. Malay Dolai ... Keywords. Coordination chemistry; nickel(II); cobalt(III); Schiff base; twisted helicity; supramolecular interactions.
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)
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...
Twisted tubular photobioreactor fluid dynamics evaluation for energy consumption minimization
Gómez-Pérez, C.A.; Espinosa Oviedo, J.J.; Montenegro Ruiz, L.C.; Boxtel, van A.J.B.
2017-01-01
This paper discusses a new tubular PhotoBioReactor (PBR) called twisted tubular PBR. The geometry of a twisted tubular PBR induces swirl mixing to guarantee good exposure of microalgae to Light-Dark (LD) cycles and to the nutrients and dissolved CO 2 . The paper analyses the energy uptake for fluid
KINEMATIC PROFILES OF DUMBBELL GALAXIES WITH TWISTED RADIO JETS
BALCELLS, M; MORGANTI, R; OOSTERLOO, T; PEREZFOURNON, [No Value; GONZALEZSERRANO, JI
1995-01-01
We study the orbital properties of dumbbell galaxies which harbor twisted radio jets. Velocity and velocity dispersion profiles for four dumbbell pairs (3C66B, 3C75, 3C449, 0326+39) are presented. We analyze optical CCD images in search of isophote off-centering and large isophote twists. Combining
Twists of genus three curves over finite fields
Meagher, Stephen; Top, Jakob
In this article we recall how to describe the twists of a curve over a finite field and we show how to compute the number of rational points on such a twist by methods of linear algebra We illustrate this in the case of plane quartic curves with at least 16 automorphisms In particular we treat the
Enhancement of heat transfer using varying width twisted tape inserts
African Journals Online (AJOL)
Enhancement of heat transfer using varying width twisted tape inserts. ... International Journal of Engineering, Science and Technology ... The present work shows the results obtained from experimental investigations of the augmentation of turbulent flow heat transfer in a horizontal tube by means of varying width twisted ...
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 ...
MHD Sausage Waves in Compressible Magnetically Twisted Flux Tubes
Fedun, Viktor
Recent high-resolution satellites clearly prove the existence of various types of theoretically predicted MHD waves in solar atmospheric magnetic structures (loops, arcades ets). Oscillations of magnetic flux tubes are of great importance as they contain information about the geometry and fine structure of the flux tubes. In this work we study the details of the effects caused by the presence of magnetic twist in flux tubes. The propagation of surface and body linear MHD modes in a twisted magnetic flux tube embedded in a magnetically twisted plasma environment is considered. We derive and analytically solve the linear governing equations of wave propagation for sausage surface and body modes of a magnetically-twisted compressible flux tube embedded in a compressible uniformly-magnetized plasma environment in cylindrical geometry in terms of Kummer's functions. Numerical solutions for the phase velocity are obtained for a wide range of wavenumbers and for varying magnetic twist. The effect of magnetic twist on the period of oscillations of sausage surface modes for different values of the wavenumber and vertical magnetic field strength is calculated for representative photospheric and coronal conditions. These results generalize and extend previous studies of MHD waves obtained for incompressible or compressible but non-twisted flux tubes. It is found that magnetic twist may change the period of sausage surface waves by the order of a few per cent when compared to counterparts in straight non-twisted flux tubes. This information will be most relevant, when high-resolution observations are used for diagnostic exploration of MHD wave guides in analogy to solar-interior studies by means of global eigenoscillations in helioseismology. Further detailed analysis is necessary in order to find the dispersion relation for more realistic cases, where the magnetic twist diminishes with distance from the tube. Finally, observational relevances will be discussed in light of the
Expression of EMT Markers SLUG and TWIST in Breast Cancer.
Grzegrzolka, Jedrzej; Biala, Martyna; Wojtyra, Patrycja; Kobierzycki, Christopher; Olbromski, Mateusz; Gomulkiewicz, Agnieszka; Piotrowska, Aleksandra; Rys, Janusz; Podhorska-Okolow, Marzena; Dziegiel, Piotr
2015-07-01
The epithelial-mesenchymal transition (EMT) has been observed in progression of in situ breast cancer to the invasive form and might be initiated by snail family zinc finger 2 (SLUG) and twist family bHLH transcription factor 1 (TWIST) protein overexpression. During this phenomenon, cells lose their epithelial phenotype and acquire mesenchymal features. The aim of the study was to examine the association of EMT markers SLUG and TWIST with clinicopathological data and the possibility of using these proteins as prognostic markers of breast cancer. Immunohistochemical analysis (IHC) of SLUG and TWIST expression was performed on archival paraffin samples of 19 cases with fibrocystic breast changes (control group), 148 cases of invasive ductal breast cancer (IDC) and 26 of invasive lobular breast cancer (ILC). Laser capture microdissection for isolation of cells from 17 frozen samples of IDC was employed and subsequently SLUG and TWIST mRNA expression in cancer and stromal cells was detected separately by real-time polymerase chain reaction. SLUG and TWIST expression in IDC was significant higher in stromal cells regardless of the method of quantification used (pSLUG mRNA, and pSLUG IHC, TWIST IHC and TWIST mRNA expression). Positive correlation of SLUG and TWIST protein and mRNA expression was observed in stromal cells of IDC (r=0.347; p<0.0001 and r=0.704; p<0.01, respectively). Expression of TWIST protein in IDC was higher in cancer cells of cases with shorter event-free survival period, as well as in stromal cells of cases with shorter overall survival period (p<0.05 for both). Stromal cells could play a role in the regulation of EMT in breast cancer. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.
Long time scale simulation of a grain boundary in copper
DEFF Research Database (Denmark)
Pedersen, A.; Henkelman, G.; Schiøtz, Jakob
2009-01-01
A general, twisted and tilted, grain boundary in copper has been simulated using the adaptive kinetic Monte Carlo method to study the atomistic structure of the non-crystalline region and the mechanism of annealing events that occur at low temperature. The simulated time interval spanned 67 mu s...... was also observed. In the final low-energy configurations, the thickness of the region separating the crystalline grains corresponds to just one atomic layer, in good agreement with reported experimental observations. The simulated system consists of 1307 atoms and atomic interactions were described using...
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)
Twisted Polynomials and Forgery Attacks on GCM
DEFF Research Database (Denmark)
Abdelraheem, Mohamed Ahmed A. M. A.; Beelen, Peter; Bogdanov, Andrey
2015-01-01
nonce misuse resistance, such as POET. The algebraic structure of polynomial hashing has given rise to security concerns: At CRYPTO 2008, Handschuh and Preneel describe key recovery attacks, and at FSE 2013, Procter and Cid provide a comprehensive framework for forgery attacks. Both approaches rely...... heavily on the ability to construct forgery polynomials having disjoint sets of roots, with many roots (“weak keys”) each. Constructing such polynomials beyond naïve approaches is crucial for these attacks, but still an open problem. In this paper, we comprehensively address this issue. We propose to use...... 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...
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)
Chiral Response of Twisted Bilayer Graphene
Stauber, T.; Low, T.; Gómez-Santos, G.
2018-01-01
We present an effective (minimal) theory for chiral two-dimensional materials. These materials possess an electromagnetic coupling without exhibiting a topological gap. As an example, we study the response of doped twisted bilayers, unveiling unusual phenomena in the zero frequency limit. An in-plane magnetic field induces a huge paramagnetic response at the neutrality point and, upon doping, also gives rise to a substantial longitudinal Hall response. The system also accommodates nontrivial longitudinal plasmonic modes that are associated with a longitudinal magnetic moment, thus endowing them with a chiral character. Finally, we note that the optical activity can be considerably enhanced upon doping and our general approach would enable systematic exploration of 2D material heterostructures with optical activity.
Emission of twisted photons from quantum vacuum
Mendonça, J. T.
2017-12-01
Emission of twisted photons, carrying orbital angular momentum, from QED vacuum is considered. This is a new type of radiation which can be excited by a Gaussian laser pulse propagating along the axis of a magnetic wiggler. We consider quantum vacuum as described by the Heisenberg-Euler Lagrangian, and assume propagation of an ultra-intense laser pulse in a static magnetic structure. We show that, in such a configuration, vacuum emission of electromagnetic vortices can occur, at a frequency much larger than that of the intense laser pulse, which can eventually be tuned from the visible up to the XUV range. This new configuration could eventually be useful to reduce classical noise in future experiments.
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)
Structural and electron diffraction scaling of twisted graphene bilayers
Zhang, Kuan; Tadmor, Ellad B.
2018-03-01
Multiscale simulations are used to study the structural relaxation in twisted graphene bilayers and the associated electron diffraction patterns. The initial twist forms an incommensurate moiré pattern that relaxes to a commensurate microstructure comprised of a repeating pattern of alternating low-energy AB and BA domains surrounding a high-energy AA domain. The simulations show that the relaxation mechanism involves a localized rotation and shrinking of the AA domains that scales in two regimes with the imposed twist. For small twisting angles, the localized rotation tends to a constant; for large twist, the rotation scales linearly with it. This behavior is tied to the inverse scaling of the moiré pattern size with twist angle and is explained theoretically using a linear elasticity model. The results are validated experimentally through a simulated electron diffraction analysis of the relaxed structures. A complex electron diffraction pattern involving the appearance of weak satellite peaks is predicted for the small twist regime. This new diffraction pattern is explained using an analytical model in which the relaxation kinematics are described as an exponentially-decaying (Gaussian) rotation field centered on the AA domains. Both the angle-dependent scaling and diffraction patterns are in quantitative agreement with experimental observations. A Matlab program for extracting the Gaussian model parameters accompanies this paper.
Topological duality twist and brane instantons in F-theory
Martucci, Luca
2014-06-01
A variant of the topological twist, involving SL(2, ℤ) dualities and hence named topological duality twist, is introduced and explicitly applied to describe a U(1) N = 4 super Yang-Mills theory on a Kähler space with holomorphically space-dependent coupling. Three-dimensional duality walls and two-dimensional chiral theories naturally enter the formulation of the duality twisted theory. Appropriately generalized, this theory is relevant for the study of Euclidean D3-brane instantons in F-theory compactifications. Some of its properties and implications are discussed.
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
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.
Synthesis of few layer single crystal graphene grains on platinum by chemical vapour deposition
Directory of Open Access Journals (Sweden)
S. Karamat
2015-08-01
Full Text Available The present competition of graphene electronics demands an efficient route which produces high quality and large area graphene. Chemical vapour deposition technique, where hydrocarbons dissociate in to active carbon species and form graphene layer on the desired metal catalyst via nucleation is considered as the most suitable method. In this study, single layer graphene with the presence of few layer single crystal graphene grains were grown on Pt foil via chemical vapour deposition. The higher growth temperature changes the surface morphology of the Pt foil so a delicate process of hydrogen bubbling was used to peel off graphene from Pt foil samples with the mechanical support of photoresist and further transferred to SiO2/Si substrates for analysis. Optical microscopy of the graphene transferred samples showed the regions of single layer along with different oriented graphene domains. Two type of interlayer stacking sequences, Bernal and twisted, were observed in the graphene grains. The presence of different stacking sequences in the graphene layers influence the electronic and optical properties; in Bernal stacking the band gap can be tunable and in twisted stacking the overall sheet resistance can be reduced. Grain boundaries of Pt provides low energy sites to the carbon species, therefore the nucleation of grains are more at the boundaries. The stacking order and the number of layers in grains were seen more clearly with scanning electron microscopy. Raman spectroscopy showed high quality graphene samples due to very small D peak. 2D Raman peak for single layer graphene showed full width half maximum (FWHM value of 30 cm−1. At points A, B and C, Bernal stacked grain showed FWHM values of 51.22, 58.45 and 64.72 cm−1, while twisted stacked grain showed the FWHM values of 27.26, 28.83 and 20.99 cm−1, respectively. FWHM values of 2D peak of Bernal stacked grain showed an increase of 20–30 cm−1 as compare to single layer graphene
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
Polanski lavastas filmi "Oliver Twist" oma lastele / Andres Laasik
Laasik, Andres, 1960-2016
2005-01-01
Mängufilm "Oliver Twist" Charles Dickensi romaani ainetel esilinastus Prahas, kus toimusid ka filmivõtted. Tšehhi, Suurbritannia, Prantsusmaa ja Itaalia koostöös valminud filmi lavastas Roman Polanski
Twisted Masses and Enhanced Symmetries: the A&D Series
Orlando, Domenico
2012-01-01
We study new symmetries between A and D type quiver gauge theories with different numbers of colors. We realize these gauge theories with twisted masses via a brane construction that reproduces all the parameters of the Gauge/Bethe correspondence.
A Novel Wavelength Demodulation Method Using Twisted High Birefringence Fiber
International Nuclear Information System (INIS)
Niu, L Y; Yang, H Y; Wu, F; Li, Z Q
2006-01-01
The mathematical model of twisted high birefringence fiber was established through theoretical analysis. A novel FBG wavelength demodulation method was put forward, by using the twisted high birefringence fiber. The numerical simulation and the experiments were carried out to the system. The standard cosine relationship was observed between the output intensity of polarization analyzer and the twist angle for the signal light with different wavelengths. When the twist angle of the high birefringence fiber is 0 and π/2, the output intensity ratio of the system presents the linear relationship with the wavelength approximately. The experiment shows that system is in agreement very well with theoretical analysis to demodulate guasi-linearly FBG wavelength shift in range of about 10 nm
Active-Twist Rotor Control Applications for UAVs
National Research Council Canada - National Science Library
Wilbur, Matthew L; Wilkie, W. K
2004-01-01
The current state-of-the-art in active-twist rotor control is discussed using representative examples from analytical and experimental studies, and the application to rotary-wing UAVs is considered...
Determination of Elastic Twist in Horizontal Axis Wind Turbines (HAWTs)
Energy Technology Data Exchange (ETDEWEB)
Stoddard, F.; Nelson, V.; Starcher, K.; Andrews, B.
2006-06-01
This report presents the results of a project at the Alternative Energy Institute (AEI) which measured and calculated the elastic twist of three representative composite horizontal-axis blades: Carter 300, Gougeon ESI 54, and UTRC 8 kW.
Migration mechanisms of a faceted grain boundary
Hadian, R.; Grabowski, B.; Finnis, M. W.; Neugebauer, J.
2018-04-01
We report molecular dynamics simulations and their analysis for a mixed tilt and twist grain boundary vicinal to the Σ 7 symmetric tilt boundary of the type {1 2 3 } in aluminum. When minimized in energy at 0 K , a grain boundary of this type exhibits nanofacets that contain kinks. We observe that at higher temperatures of migration simulations, given extended annealing times, it is energetically favorable for these nanofacets to coalesce into a large terrace-facet structure. Therefore, we initiate the simulations from such a structure and study as a function of applied driving force and temperature how the boundary migrates. We find the migration of a faceted boundary can be described in terms of the flow of steps. The migration is dominated at lower driving force by the collective motion of the steps incorporated in the facet, and at higher driving forces by the step detachment from the terrace-facet junction and propagation of steps across the terraces. The velocity of steps on terraces is faster than their velocity when incorporated in the facet, and very much faster than the velocity of the facet profile itself, which is almost stationary. A simple kinetic Monte Carlo model matches the broad kinematic features revealed by the molecular dynamics. Since the mechanisms seem likely to be very general on kinked grain-boundary planes, the step-flow description is a promising approach to more quantitative modeling of general grain boundaries.
Energy Spectrum and Quantum Hall Effect in Twisted Bilayer Graphene
Moon, Pilkyung; Koshino, Mikito
2012-01-01
We investigate the electronic spectra and quantum Hall effect in twisted bilayer graphenes with various rotation angles under magnetic fields, using a model rigorously including the interlayer interaction. We describe the spectral evolution from discrete Landau levels in the weak field regime to the fractal band structure in the strong field regime, and estimate the quantized Hall conductivity for each single gap. In weak magnetic fields, the low-energy conduction band of the twisted bilayer ...
Active-Twist Rotor Control Applications for UAVs
Wilbur, Matthew L.; Wilkie, W. Keats
2004-01-01
The current state-of-the-art in active-twist rotor control is discussed using representative examples from analytical and experimental studies, and the application to rotary-wing UAVs is considered. Topics include vibration and noise reduction, rotor performance improvement, active blade tracking, stability augmentation, and rotor blade de-icing. A review of the current status of piezoelectric fiber composite actuator technology, the class of piezoelectric actuators implemented in active-twist rotor systems, is included.
Polarisation of microwave emission from reconnecting twisted coronal loops
Gordovskyy, M.; Browning, P. K.; Kontar, E. P.
2017-08-01
Context. Magnetic reconnection and particle acceleration due to the kink instability in twisted coronal loops can be a viable scenario for confined solar flares. Detailed investigation of this phenomenon requires reliable methods for observational detection of magnetic twist in solar flares, which may not be possible solely through extreme UV and soft X-ray thermal emission. Polarisation of microwave emission in flaring loops can be used as one of the detection criteria. Aims: The aim of this study is to investigate the effect of magnetic twist in flaring coronal loops on the polarisation of gyro-synchrotron microwave (GSMW) emission, and determine whether it could provide a means for magnetic twist detection. Methods: We consider time-dependent magnetohydrodynamic and test-particle models developed using the LARE3D and GCA codes to investigate twisted coronal loops that relax after kink instability. Synthetic GSMW emission maps (I and V Stokes components) are calculated using GX simulator. Results: It is found that flaring twisted coronal loops produce GSMW radiation with a gradient of circular polarisation across the loop. However, these patterns may be visible only for a relatively short period of time owing to fast magnetic reconfiguration after the instability. Their visibility also depends on the orientation and position of the loop on the solar disk. Typically, it would be difficult to see these characteristic polarisation patterns in a twisted loop seen from the top (I.e. close to the centre of the solar disk), but easier in a twisted loop seen from the side (I.e. observed very close to the limb).
Wear characteristics of UHMW polyethylene by twist method
Chișiu, G.; Popescu, A. M.; Tudor, A.; Petrescu, A. M.; Stoica, G. F.; Subhi, K. A.
2018-01-01
A wear test of the twist movement was performed as a new method to estimate the in vivo wear behavior of an acetabular cup material for total knee replacements. A series of UHMWPE samples was used to evaluate the dynamic coefficient of friction in twist movement in contact with steel. The experimental data were conducted to validate the related theoretical model developed in the present study.
Twist decomposition of Drell-Yan structure functions: phenomenological implications
Energy Technology Data Exchange (ETDEWEB)
Brzemiński, Dawid [Institute of Physics, Jagiellonian University,S. Łojasiewicza 11, 30-348 Kraków (Poland); Cavendish Laboratory, University of Cambridge,19 J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Motyka, Leszek; Sadzikowski, Mariusz; Stebel, Tomasz [Institute of Physics, Jagiellonian University,S. Łojasiewicza 11, 30-348 Kraków (Poland)
2017-01-02
The forward Drell-Yan process in pp scattering at the LHC at √S=14 TeV is considered. We analyze the Drell-Yan structure functions assuming the dominance of a Compton-like emission of a virtual photon from a fast quark scattering off the small x gluons. The color dipole framework is applied to perform quantitatively the twist decomposition of all the Drell-Yan structure functions. Two models of the color dipole scattering are applied: the Golec-Biernat-Wüsthoff model and the dipole cross section obtained from the Balitsky-Fadin-Kuraev-Lipatov evolution equation. The two models have essentially different higher twist content and the gluon transverse momentum distribution and lead to different significant effects beyond the collinear leading twist description. It is found that the gluon transverse momentum effects are significant in the Drell-Yan structure functions for all Drell-Yan pair masses M, and the higher twist effects become important for M≲10 GeV. It is found that the structure function W{sub TT} related to the A{sub 2} angular coefficient and the Lam-Tung observable A{sub 0}−A{sub 2} are particularly sensitive to the gluon k{sub T} effects and to the higher twist effects. A procedure is suggested how to disentangle the higher twist effects from the gluon transverse momentum effects.
How the embryonic chick brain twists
Guo, Qiaohang; Dai, Eric; Forsch, Nickolas; Taber, Larry A.
2016-01-01
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. PMID:28334695
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].
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.
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.)
Universal corner entanglement from twist operators
Energy Technology Data Exchange (ETDEWEB)
Bueno, Pablo [Instituto de Física Teórica UAM/CSIC, C/Nicolás Cabrera, 13-15, C.University Cantoblanco, 28049 Madrid (Spain); Myers, Robert C.; Witczak-Krempa, William [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, ON N2L 2Y5 (Canada)
2015-09-15
The entanglement entropy in three-dimensional conformal field theories (CFTs) receives a logarithmic contribution characterized by a regulator-independent function a(θ) when the entangling surface contains a sharp corner with opening angle θ. In the limit of a smooth surface (θ→π), this corner contribution vanishes as a(θ)=σ (θ−π){sup 2}. In http://arxiv.org/abs/1505.04804, we provided evidence for the conjecture that for any d=3 CFT, this corner coefficient σ is determined by C{sub T}, the coefficient appearing in the two-point function of the stress tensor. Here, we argue that this is an instance of a much more general relation connecting the analogous corner coefficient σ{sub n} appearing in the nth Rényi entropy and the scaling dimension h{sub n} of the corresponding twist operator. In particular, we find the simple relation h{sub n}/σ{sub n}=(n−1)π. We show how it reduces to our previous result as n→1, and explicitly check its validity for free scalars and fermions. With this new relation, we show that as n→0, σ{sub n} yields the coefficient of the thermal entropy, c{sub S}. We also reveal a surprising duality relating the corner coefficients of the scalar and the fermion. Further, we use our result to predict σ{sub n} for holographic CFTs dual to four-dimensional Einstein gravity. Our findings generalize to other dimensions, and we emphasize the connection to the interval Rényi entropies of d=2 CFTs.
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.
Comments on twisted indices in 3d supersymmetric gauge theories
Energy Technology Data Exchange (ETDEWEB)
Closset, Cyril [Simons Center for Geometry and PhysicsState University of New York, Stony Brook, NY 11794 (United States); Kim, Heeyeon [Perimeter Institute for Theoretical Physics31 Caroline Street North, Waterloo, N2L 2Y5, Ontario (Canada)
2016-08-09
We study three-dimensional N=2 supersymmetric gauge theories on Σ{sub g}×S{sup 1} with a topological twist along Σ{sub g}, a genus-g Riemann surface. The twisted supersymmetric index at genus g and the correlation functions of half-BPS loop operators on S{sup 1} can be computed exactly by supersymmetric localization. For g=1, this gives a simple UV computation of the 3d Witten index. Twisted indices provide us with a clean derivation of the quantum algebra of supersymmetric Wilson loops, for any Yang-Mills-Chern-Simons-matter theory, in terms of the associated Bethe equations for the theory on ℝ{sup 2}×S{sup 1}. This also provides a powerful and simple tool to study 3d N=2 Seiberg dualities. Finally, we study A- and B-twisted indices for N=4 supersymmetric gauge theories, which turns out to be very useful for quantitative studies of three-dimensional mirror symmetry. We also briefly comment on a relation between the S{sup 2}×S{sup 1} twisted indices and the Hilbert series of N=4 moduli spaces.
Terminal twist-induced writhe of DNA with intrinsic curvature.
Hu, Kai
2007-04-01
Supercoiling of a closed circular DNA rod may result from an application of terminal twist to the DNA rod by cutting the rod, rotating one of the cut faces as the other being fixed and then sealing the cut. According to White's formula, DNA supercoiling is probably accompanied by a writhe of the DNA axis. Deduced from the elastic rod model for DNA structure, an intrinsically straight closed circular DNA rod does not writhe as subject to a terminal twist, until the number of rotation exceeds a rod-dependent threshold. By contrast, a closed circular DNA rod with intrinsic curvature writhes instantly as subject to a terminal twist. This noteworthy character in fact belongs to many intrinsically curved DNA rods. By solving the dynamic equations, the linearization of the Euler-Lagrange equations governing intrinsically curved DNA rods, this paper shows that almost every clamped-end intrinsically curved DNA rod writhes instantly when subject to a terminal twist (clamped-end DNA rods include closed circular DNA rods and topological domains of open DNA rods). In terms of physical quantities, the exceptions are identified with points in R(6) whose projections onto R(5) (through ignoring the total energy density of a rod) form a subset of a quadratic hypersurface. This paper also suggests that the terminal twist induced writhe is due to the elasticity and the clamped-end boundary conditions of the DNA rods.
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.
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.
Wu, Shuai; Zhan, Hai-yi; Wang, Hong-ming; Ju, Yan
2012-04-01
The secondary structure of different Iβ cellulose was analyzed by a molecular dynamics simulation with MARTINI coarse-grained force field, where each chain of the cellulose includes 40 D-glucoses units. Calculation gives a satisfied description about the secondary structure of the cellulose. As the chain number increasing, the cellulose becomes the form of a helix, with the diameter of screw growing and spiral rising. Interestingly, the celluloses with chain number N 4 of 6, 24 and 36 do show right-hand twisting. On the contrast, the celluloses with N 8 of 12, 16 chains are left-hand twisting. These simulations indicate that the cellulose with chain number larger than 36 will break down to two parts. Besides, the result indicates that 36-chains cellulose model is the most stable among all models. Furthermore, the Lennard-Jones potential determines the secondary structure. In addition, an equation was set up to analyze the twisting structure.
Three-dimensional mechanical metamaterials with a twist.
Frenzel, Tobias; Kadic, Muamer; Wegener, Martin
2017-11-24
Rationally designed artificial materials enable mechanical properties that are inaccessible with ordinary materials. Pushing on an ordinary linearly elastic bar can cause it to be deformed in many ways. However, a twist, the counterpart of optical activity in the static case, is strictly zero. The unavailability of this degree of freedom hinders applications in terms of mode conversion and the realization of advanced mechanical designs using coordinate transformations. Here, we aim at realizing microstructured three-dimensional elastic chiral mechanical metamaterials that overcome this limitation. On overall millimeter-sized samples, we measure twists per axial strain exceeding 2°/%. Scaling up the number of unit cells for fixed sample dimensions, the twist is robust due to metamaterial stiffening, indicating a characteristic length scale and bringing the aforementioned applications into reach. Copyright © 2017, American Association for the Advancement of Science.
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
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)
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.
Note on the rank of quadratic twists of Mordell equations
Chang, Sungkon
2005-01-01
14H52 : Elliptic curves Let E be the elliptic curve given by a Mordell equation y^2=x^3-A where A is an integer. For certain A, we use Stoll's formula to compute a lower bound for the proportion of square-free integers D up to X such that the Mordell-Weil rank of the quadratic twist by D is less than 2k, for given non-negative k. We also compute an upper bound for a certain average rank of quadratic twists of E.
On the role of higher twists in describing scaling violation
International Nuclear Information System (INIS)
Chyla, J.; Rames, J.
1986-06-01
A method of comparing the QCD predictions for nucleon structure functions scaling violation with deep inelastic scattering data is proposed, the main feature of which being the assumption that the value of Λ QCD parameter is known independently of perturbative analyses. We conjecture that a suitable way of determination Λ is through lattice Monte Carlo calculations of quantities like hadronic masses and consider the Λ MS -bar value thus found around 100 MeV. The method is then used for quantitative analysis of twist 4 contributions, and problems related to higher twist effects determination are discussed
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
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)
Tomislav Pogačić
2013-03-01
Full Text Available Kefir grains represent the unique microbial community consisting of bacteria, yeasts, and sometimes filamentous moulds creating complex symbiotic community. The complexity of their physical and microbial structures is the reason that the kefir grains are still not unequivocally elucidated. Microbiota of kefir grains has been studied by many microbiological and molecular approaches. The development of metagenomics, based on the identification without cultivation, is opening new possibilities for identification of previously nonisolated and non-identified microbial species from the kefir grains. Considering recent studies, there are over 50 microbial species associated with kefir grains. The aim of this review is to summarise the microbiota composition of kefir grains. Moreover, because of technological and microbiological significance of the kefir grains, the paper provides an insight into the microbiological and molecular methods applied to study microbial biodiversity of kefir grains.
DEFF Research Database (Denmark)
Tran, Phuoc T; Shroff, Emelyn H; Burns, Timothy F
2012-01-01
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....... 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...
Ridenour, Harlan E.
This vocational agriculture curriculum on grain marketing contains three parts: teacher guide, student manual, and student workbook. All three are coordinated and cross-referenced. The course is designed to give students of grain marketing a thorough background in the subject and provide practical help in developing grain marketing strategies for…
Vafa-Witten theory on N = 2 and N = 4 twisted superspace in four dimensions
International Nuclear Information System (INIS)
Kato, Junji; Miyake, Akiko
2009-01-01
We construct a new off-shell twisted real form of the hypermultiplet with a scalar and an anti-self-dual tensor superfields. Using the N = 2 twisted superspace formalism, we construct a Donaldson-Witten theory coupled to the real form of the hypermultiplet. We show that this action possesses the Vafa-Witten type N = 4 twisted supersymmetry at the on-shell level. We also reconstruct the action using a N = 4 twisted superconnection formalism.
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.
Mathematical simulation of a twisted pseudoplastic fluid flow in a cylindrical channel
Matvienko, O. V.; Bazuev, V. P.; Yuzhanova, N. K.
2011-05-01
The results of investigations of a pseudoplastic fluid twisted flow in a cylindrical channel are presented. With increase in the shear stresses caused by the flow twisting, the effective viscosity decreases. As a result, in the axial part of the channel a zone of lower pressure is formed which, at smaller flow twisting, leads to the formation of the zone of backward flows.
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
Conservative Management of Twisted Ischemic Adnexa in Early ...
African Journals Online (AJOL)
She underwent emergency surgery with a provisional diagnosis of torsion of left adnexa. Mini‑laparotomy, detorsion of the twisted adnexa and ovarian cystectomy with reconstruction was performed thus conserving the tube and ovary. The pregnancy progressed normally; follow‑up ultrasound scans showed normal ...
The Hardy inequality and the heat equation in twisted tubes
Czech Academy of Sciences Publication Activity Database
Krejčiřík, David; Zuazua, E.
2010-01-01
Roč. 94, č. 3 (2010), s. 277-303 ISSN 0021-7824 R&D Projects: GA MŠk LC06002 Institutional research plan: CEZ:AV0Z10480505 Keywords : Twisted tubes * Hardy inequality * Dirichlet Laplacian Subject RIV: BA - General Mathematics Impact factor: 1.450, year: 2010
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.
Twisted topological solitons and dislocations in a polymer crystal
DEFF Research Database (Denmark)
Savin, A. V.; Khalack, J. M.; Christiansen, Peter Leth
2002-01-01
of adjacent molecular chains in the polymer crystal). It is shown that some of these defects called "twisted topological solitons" can propagate with a stationary profile and velocity. To describe the dynamics of these solitons, a model that accounts for the three components of the molecular displacements...
A Hardy inequality in a twisted Dirichlet-Neumann waveguide
Czech Academy of Sciences Publication Activity Database
Kovařík, Hynek; Krejčiřík, David
2008-01-01
Roč. 281, č. 8 (2008), s. 1159-1168 ISSN 0025-584X R&D Projects: GA MŠk LC06002 Institutional research plan: CEZ:AV0Z10480505 Keywords : Laplacian * Dirichlet and Neumann boundary conditions * twist Subject RIV: BE - Theoretical Physics Impact factor: 0.537, year: 2008
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
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
Would You Rather (WYR), with a Sexual Health Twist!
Rosen, Brittany; McNeill, Elisa Beth; Wilson, Kelly
2014-01-01
Would You Rather (WYR), with a Sexual Health Twist! teaching technique uses two youth games, "Would you rather…" and Twister®, to actively engage students in developing decision-making skills regarding human sexuality. Utilizing the "Would you rather" choices, the teacher provides a short scenario with two difficult choices.…
Coherent nonlinear electromagnetic response in twisted bilayer and ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 83; Issue 4. Coherent nonlinear electromagnetic response in twisted bilayer and few-layer graphene ... These oscillations in the population and polarization at the Dirac point in -layer graphene are seen in the nth harmonic termin the external driving frequency.
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
Twist of Magnetic Fields in Solar Active Regions Hongqi Zhang ...
Indian Academy of Sciences (India)
tribpo
twisted field (current helicity) in the photosphere (Seehafer 1990; Pevtsov et al. 1995;. Bao & Zhang 1998). Bao & Zhang (1998) and Zhang & Bao (1999) computed the photospheric current helicity parameter h|| for 422 active regions, including most of the large ones observed in the period of 1988 1997 at Huairou Solar ...
Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening ...
Indian Academy of Sciences (India)
tribpo
netic field, which subsequently appear as active regions in the photosphere (Rust &. Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Raman et al. 1998 and the references therein).
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
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)
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
Directory of Open Access Journals (Sweden)
Emilia Mary Bălan
2017-04-01
Full Text Available Grain is part of agricultural commodities and is of utmost importance for world agriculture,since it is the essential element of food and animal feed. Against this background, grain trade among countries of the world is dynamic and represents about 10% of global trade in food products.This article examines global grain trade both in terms of quantitative and qualitative developments, and highlights the most important competitor countries in this sector. It also details the patterns of grain trade for the world's main exporters and importers of such commodities.Two distinct sections of the research relate to the evolution of the primary grain quotations(wheat, corn, barley, rice and sorghum at the most representative international agricultural commodities markets (Chicago Board of Trade, based on a comprehensive statistical analysis, and the short-term forecasts for global grain trade, respectively.
Sudden polarization effect in methyl-substituted twisted polyenes
International Nuclear Information System (INIS)
Baraldi, I.; Bruni, M.C.; Momicchioli, F.; Ponterini, G.
1981-01-01
Sudden polarization effect was investigated for a special type of nonsymmetric biradical systems, i.e. terminally twisted polyenes methyl substituted at the rotated CH 2 group. Systems with 2 to 4 conjugated double bonds were studied. Dipole moments of S 0 , S 1 and S 2 states were calculated within the framework of the INDO approximations, by using a dual basis of SCF MOs (open shell and closed shell) and performing differently sized CIs (selected with reference to the basic 3 x 3 CI biradical description). The resulting excited-state polarization characteristics (size and suddenness) are discussed with reference to the previously studied unsubstituted polyenes. In this respect the most important point is that CH 3 substitution at the terminal twisted methylene markedly enhances the polarization size (approximately 2D). This indicates that small perturbations occurring at one radical site may cause unexpectedly large changes in charge distributions of excited biradicals. (author)
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.
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.)
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.
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.
Spin squeezing in a generalized one-axis twisting model
Jin, Guang-Ri; Liu, Yong-Chun; Liu, Wu-Ming
2009-07-01
We investigate the dependence of spin squeezing on the polar angle of the initial coherent spin state |θ0, phi0rang in a generalized one-axis twisting model, where the detuning δ is taken into account. We show explicitly that regardless of δ and phi0, previous results of the ideal one-axis twisting are recovered as long as θ0=π/2. For a small departure of θ0 from π/2, however, the achievable variance (V -)min ~N2/3, which is larger than the ideal case N1/3. We also find that the maximal squeezing time tmin scales as N-5/6. Analytic expressions of (V-)min and tmin are presented and they agree with numerical simulations.
A generalized network representation of twist-reflectors
International Nuclear Information System (INIS)
Rebuffi, L.
1986-06-01
A general network representation of different kinds of Twist-Reflector (T.R.) is presented. By mean of a TM- and TE-type modal representation of the fields, using a double equivalent circuit it is possible to describe a strip, parallel plate or corrugated surface T.R. Modal reflection coefficients GAMMA' and GAMMA'' are derived starting from Marcuvitz formulations [1 ] and adapting them to different tested mirrors. Theoretic-empirical circuit parameters are thus deduced to satisfy the two basic conditions for an optimal design. The strip and the plate thickness is considered to be finite, thus reducing the degree of approximation. Using this model, predicted theoretical values for the reflector efficiency are in close agreement with experimental results, thus permitting a correct design of different kinds of Twist-Reflector
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.
Orienting Asymmetric Molecules by Laser Fields with Twisted Polarization
Gershnabel, E.; Averbukh, I. Sh.
2018-02-01
We study interaction of generic asymmetric molecules with laser fields having twisted polarization, using a pair of strong time-delayed short laser pulses with crossed linear polarizations as an example. We show that such an excitation not only provides unidirectional rotation of the most polarizable molecular axis, but also induces a directed torque along this axis, which results in a transient orientation of the molecules. The asymmetric molecules are chiral in nature and different molecular enantiomers experience the orienting action in opposite directions causing out-of-phase oscillations of their dipole moments. The resulting microwave radiation was recently suggested to be used for analysis or discrimination of chiral molecular mixtures. We reveal the mechanism behind this laser-induced orientation effect, show that it is classical in nature, and envision further applications of light with twisted polarization.
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.
Gao, X.; Nittler, L. R.; Swan, P. D.; Walker, R. M.
1995-09-01
We report results for the EH(4) Indarch. Earlier work [1] found 20 micrometers clumps of sub-micron SiC whose presolar nature was inferred from step-wise combustion, noble gas [2], and ion probe isotopic measurements. Our results indicate that the clumps were an artifact of sample preparation. Our sample was first cleaned using 6N HCl, and water and isopropanol rinses, then powdered and reacted with HCl-HF/HCl, KOH, and H3BO3-HCl/HCl giving a C-rich residue 1.14 wt.% of the original. X-ray mapping showed SiC grains and 5x as many Si3N4 grains, but no fine-grained clumps. Large (6 micrometers to 20 micrometers) C-rich spheroids were also present. The sample was further treated with KOH/HNO3 and NH3H2O; attempts to do density-separates were unsuccessful. An aliquot was treated with perchloric acid and separated into 1 micrometer fractions. SEM-EDS measurements of 73 (1 micrometer) grains with the addition of 2 spinel and one Al2O3 grains. The whole rock concentration of SiC was 5.8 ppm, higher than previous determinations [1,3,9]. Confirming earlier suggestions [1,2], we find that SiC in Indarch is much finer-grained than in Murchison; about 2/3 of the mass is in grains size-sorting in the nebula or selective destruction of fine-grained material. Ion probe measurements of 22 (1-3 micrometers) grains gave isotopic results in the range previously measured for Murchison SiCs [4]. Several normal Si3N4 grains (>1 micron) were measured; probably exsolution products similar to those in Qingzhen [7]. Ion mapping was used to search for presolar oxide grains using previously developed techniques [5]. Seven candidate grains out of ~1000 were found. Multiple imaging confirmed an ^(16)O/^(18)O anomaly in one spinel grain - the first presolar oxide found in an E chondrite. Although the proportion of oxide grains relative to SiC is smaller, the fraction of anomalous oxide grains is not strikingly different in Indarch than in Murchison (1/1000) or Tieschitz (1/300). Prior ion probe
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
Internal twist drill coolant channel modelling using computational fluid dynamics
Johns, AS; Hewson, RW; Merson, E; Summers, JL; Thompson, HM
2014-01-01
Coolant technologies have become increasingly used within twist-drill machining. Internal helical coolant channels are a common means of delivering high-pressure coolant directly to the cutting edge to increase the transfer of heat away from the cutting edge and to aid with chip evacuation. However, the complex behaviour of Coriolis and centrifugal forces generated by large angular velocities and the curvature of the coiled channel govern the highly turbulent flow of coolant. This research us...
... Every time you choose to eat a starchy food, make it count! Leave the processed white flour-based products, especially the ones with added ... wheat grain is ground up. "Refined" flours like white and enriched wheat flour include only ... whole grain foods can be a challenge. Some foods only contain ...
Report on twisted nematic and supertwisted nematic device characterization program
1995-01-01
In this study we measured the optical characteristics of normally white twisted nematic (NWTN) and super twisted nematic (STN ) cells. Though no dynamic computer model was available, the static observations were compared with computer simulated behavior. The measurements were taken as a function of both viewing angle and applied voltage and included in the static case not only luminance but also contrast ratio and chromaticity . We employed the computer model Twist Cell Optics, developed at Kent State in conjunction with this study, and whose optical modeling foundation, Iike the ViDEOS program, is the 4 x 4 matrix method of Berreman. In order to resolve discrepancies between the experimental and modeled data the optical parameters of the individual cell components, where not known, were determined using refractometry, profilometry, and various forms of ellipsometry. The resulting agreement between experiment and model is quite good due primarily to a better understanding of the structure and optics of dichroic sheet polarizers. A description of the model and test cells employed are given in section 2. Section 3 contains the experimental data gathered and section 4 gives examples of the fit between model and experiment. Also included with this report are a pair of papers which resulted from the research and which detail the polarizer properties and some of the cell characterization methods.
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)
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.
Management Options for Twisted Gastric Tube after Laparoscopic Sleeve Gastrectomy.
Abd Ellatif, Mohamed E; Abbas, Ashraf; El Nakeeb, Ayman; Magdy, Alaa; Salama, Asaad F; Bashah, Moataz M; Dawoud, Ibrahim; Gamal, Maged Ali; Sargsyan, Davit
2017-09-01
This study aims to determine the incidence, etiology, and management options for symptomatic gastric obstruction caused by axially twisted sleeve gastrectomy. In this retrospective study, we reviewed medical charts of all morbidly obese patients who underwent laparoscopic sleeve gastrectomy. Patients who developed gastric obstruction symptoms and were diagnosed with twisted sleeve gastrectomy were identified and included in this study. From October 2005 to December 2015, there are 3634 morbidly obese patients who underwent laparoscopic sleeve gastrectomy (LSG). Eighty-six (2.3%) patients developed symptoms of gastric obstruction. Forty-five (1.23%) patients were included in this study. The mean time of presentation was 59.8 days after surgery. Upper GI contrast study was done routinely, and it was positive for axial twist in 37 (82%) patients. Abdominal CT with oral and IV contrast was done in eight (18%) when swallow study was equivocal. Endoscopic treatment was successful in 43 patients (95.5%). Sixteen patients were successfully managed by endoscopic stenting, and 29 patients had balloon dilation. The average numbers of dilation sessions were 1.7. Out of these 29 patients, 18 responded well to a single session of dilatation and did not require any further dilatation sessions. Two patients who failed to respond to three subsequent sessions of balloon dilation underwent laparoscopic adhesiolysis and gastropexy. Endoscopic stenting is an effective tool in management of axial rotation of sleeved stomach. Balloon dilation can also be effective in selected cases. Few cases might require laparoscopic adhesiolysis and gastropexy.
Crystal Engineering of Hand-Twisted Helical Crystals.
Saha, Subhankar; Desiraju, Gautam R
2017-02-08
A strategy is outlined for the design of hand-twisted helical crystals. The starting point in the exercise is the one-dimensional (1D) plastic crystal, 1,4-dibromobenzene, which is then changed to a 1D elastic crystal, exemplified by 4-bromophenyl 4'-chlorobenzoate, by introduction of a molecular synthon -O-CO- in lieu of the supramolecular synthon Br···Br in the precursor. The 1D elastic crystals are next modified to two-dimensional (2D) elastic crystals, of the type 4-bromophenyl 4'-nitrobenzoate where the halogen bonding and C-H···O hydrogen bonding are well-matched. Finally, varying the interaction strengths in these 2D elastic crystals gives plastic crystals with two pairs of bendable faces but without slip planes. Typical examples are 4-chlorophenyl and 4-bromophenyl 4'-nitrobenzoate. This type of 2D plasticity represents a new type of bendable crystals in which plastic behavior is seen with a fair degree of isotropic character in the crystal packing. The presence of two sets of bendable faces, generally orthogonal to each other, allows for the possibility of hand-twisting of the crystals to give grossly helical morphologies. Accordingly, we propose the name hand-twisted helical crystals for these substances.
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...
Moiré-related in-gap states in a twisted MoS2/graphite heterojunction
Lu, Chun-I
2017-07-21
This report presents a series of low-temperature (4.5 K) scanning tunneling microscopy and spectroscopy experimental results on monolayer MoS2 deposited on highly oriented pyrolytic graphite using chemical vapor deposition. To reveal the detailed connection between atomic morphology and conductivity in twisted MoS2/graphite heterojunctions, we employ high-sensitivity tunneling spectroscopy measurements by choosing a reduced tip-sample distance. We discern previously unobserved conductance peaks within the band gap range of MoS2, and by comparing the tunneling spectra from MoS2 grains of varying rotation with respect to the substrate, show that these features have small but non-negligible dependence on the moiré superstructure. Furthermore, within a single moiré supercell, atomically resolved tunneling spectroscopy measurements show that the spectra between the moiré high and low areas are also distinct. These in-gap states are shown to have an energy shift attributed to their local lattice strain, matching corresponding behavior of the conduction band edge, and we therefore infer that these features are intrinsic to the density of states, rather than experimental artifacts, and attribute them to the twisted stacking and local strain energy of the MoS2/graphite heterointerface.
Role of left ventricular twist mechanics in cardiomyopathies, dance of the helices.
Kauer, Floris; Geleijnse, Marcel Leonard; van Dalen, Bastiaan Martijn
2015-08-26
Left ventricular twist is an essential part of left ventricular function. Nevertheless, knowledge is limited in "the cardiology community" as it comes to twist mechanics. Fortunately the development of speckle tracking echocardiography, allowing accurate, reproducible and rapid bedside assessment of left ventricular twist, has boosted the interest in this important mechanical aspect of left ventricular deformation. Although the fundamental physiological role of left ventricular twist is undisputable, the clinical relevance of assessment of left ventricular twist in cardiomyopathies still needs to be established. The fact remains; analysis of left ventricular twist mechanics has already provided substantial pathophysiological understanding on a comprehensive variety of cardiomyopathies. It has become clear that increased left ventricular twist in for example hypertrophic cardiomyopathy may be an early sign of subendocardial (microvascular) dysfunction. Furthermore, decreased left ventricular twist may be caused by left ventricular dilatation or an extensive myocardial scar. Finally, the detection of left ventricular rigid body rotation in noncompaction cardiomyopathy may provide an indispensible method to objectively confirm this difficult diagnosis. All this endorses the value of left ventricular twist in the field of cardiomyopathies and may further encourage the implementation of left ventricular twist parameters in the "diagnostic toolbox" for cardiomyopathies.
Relationship between lattice mismatch and ionic conduction of grain boundary in YSZ
Directory of Open Access Journals (Sweden)
Fei Ye
2014-02-01
Full Text Available The grain boundary plays an important role in the electrical behaviors of solid oxide electrolytes for solid state fuel cells. To reveal the relationship between the structure and the ionic conductivity of grain boundary, the conductive properties of {1 1 1} and {1 1 0} twist grain boundaries in 8 mol% yttria-stabilized zirconia have been examined. These boundaries have a series of Σ values defined by the coincident site lattice model. It has been found that the activation energy of {1 1 1} twist grain boundary increases and then decreases with the Σ value, while that of the {1 1 0} boundary shows an opposite trend. It is suggested that the properties can reflect the balance of the effects of lattice mismatch on the diffusion ability of oxygen vacancies and the segregation of oxygen vacancies and Y3+ ions. Therefore, the properties in polycrystalline electrolyte can be adjusted by controlling the grain boundary structures.
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)
... Grains All about the Grains Group Print Share What foods are in the Grains Group? Any food made ... Whole Grains Food Gallery Take the Grains Quiz What Is MyPlate? Food Guide History MyPlate, MyWins Fruits All About the ...
Wang, Li; Tan, Rui-Zhi; Zhang, Zhi-Xia; Yin, Rui; Zhang, Yong-Liang; Cui, Wei-Jia; He, Tao
2018-01-01
Multidrug resistance (MDR) severely limits the effectiveness of chemotherapy. Previous studies have identified Twist as a key factor of acquired MDR in breast, gastric and prostate cancer. However, the underlying mechanisms of action of Twist in MDR remain unclear. In the present study, the expression levels of MDR-associated proteins, including lung resistance-related protein (LRP), topoisomerase IIα (TOPO IIα), MDR-associated protein (MRP) and P-glycoprotein (P-gp), and the expression of Twist in cancerous tissues and pericancerous tissues of human breast cancer, were examined. In order to simulate Taxol ® resistance in cells, a Taxol ® -resistant human mammary adenocarcinoma cell subline (MCF-7/Taxol ® ) was established by repeatedly exposing MCF-7 cells to high concentrations of Taxol ® (up to 15 µg/ml). Twist was also overexpressed in 293 cells by transfecting this cell line with pcDNA5/FRT/TO vector containing full-length hTwist cDNA to explore the dynamic association between Twist and MDR gene-associated proteins. It was identified that the expression levels of Twist, TOPO IIα, MRP and P-gp were upregulated and LRP was downregulated in human breast cancer tissues, which was consistent with the expression of these proteins in the Taxol ® -resistant MCF-7 cell model. Notably, the overexpression of Twist in 293 cells increased the resistance to Taxol ® , Trichostatin A and 5-fluorouracil, and also upregulated the expression of MRP and P-gp. Taken together, these data demonstrated that Twist may promote drug resistance in cells and cancer tissues through regulating the expression of MDR gene-associated proteins, which may assist in understanding the mechanisms of action of Twist in drug resistance.
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.)
Large Variations of the Raman Signal in the Spectra of Twisted Bilayer Graphene on a BN Substrate.
Kalbac, Martin; Frank, Otakar; Kong, Jing; Sanchez-Yamagishi, Javier; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo; Dresselhaus, Mildred S
2012-03-15
We report an unusual enhancement of the Raman signal of the G mode in a twisted graphene bilayer (2-LG) on a hexagonal single-crystalline boron nitride substrate. We used an isotopically engineered 2-LG, where the top layer was composed of (13)C atoms and the bottom layer of (12)C atoms. Consequently, it was possible by Raman spectroscopy to distinguish between the enhancement coming from the top and bottom layers. The enhancement of the G mode was, however, found to be similar for the top and bottom layers, and this enhancement effect was observed only at certain locations on the substrate. The experiment with two different laser excitation energies showed that the location of the enhanced spots is dependent on the laser excitation energy. Therefore our results suggest that the enhancement comes from new states in the electronic structure, which are a consequence of a local specific rotation of the grains in graphene layers.
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.
International Nuclear Information System (INIS)
Buch, V.
1990-01-01
This chapter discusses the chemical evolution and composition of dust in dense interstellar clouds. Studies use observations in the infrared, visible and ultraviolet spectral regions. These grains are thought to be made largely of highly disordered and/or composite materials. Recently acquired data on Halley's comet and on the structure, composition and spectral properties of interplanetary dust particles (IDP) are used to study grain chemistry. These substances are though to be similar to dense cloud dust. Dense clouds are thought to contain minerals, poorly crystallized carbonaceous/organic polymers, coating mineral grains and dirty ice mantles and the chemistry of these substances is considered. (UK)
Kansas Agents Study Grain Marketing
Schoeff, Robert W.
1973-01-01
Author is an extension specialist in feed and grain marketing for Kansas State University. He describes a tour set up to educate members of the Kansas Grain and Feed Dealers' Association in the area of grain marketing and exporting. (GB)
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...
A general-purpose coarse-grained molecular dynamics program
Aoyagi, Takeshi; Sawa, Fumio; Shoji, Tatsuya; Fukunaga, Hiroo; Takimoto, Jun-ichi; Doi, Masao
2002-05-01
In this article, we describe a general-purpose coarse-grained molecular dynamics program COGNAC ( COarse Grained molecular dynamics program by NAgoya Cooperation). COGNAC has been developed for general molecular dynamics simulation, especially for coarse-grained polymer chain models. COGNAC can deal with general molecular models, in which each molecule consists of coarse-grained atomic units connected by chemical bonds. The chemical bonds are specified by bonding potentials for the stretching, bending and twisting of the bonds, each of which are the functions of the position coordinates of the two, three and four atomic units. COGNAC can deal with both isotropic and anisotropic interactions between the non-bonded atomic units. As an example, the Gay-Berne potential is implemented. New potential functions can be added to the list of existing potential functions by users. COGNAC can do simulations for various situations such as under constant temperature, under constant pressure, under shear and elongational deformation, etc. Some new methods are implemented in COGNAC for modeling multiphase structures of polymer blends and block copolymers. A density biased Monte Carlo method and a density biased potential method can generate equilibrium chain configurations from the results of the self-consistent field calculations. Staggered reflective boundary conditions can generate interfacial structures with smaller system size compared with those of periodic boundary conditions.
... of many nutrients: B vitamins (thiamin (Vitamin B1), riboflavin (Vitamin B2), niacin (Vitamin B3) and folate (Vitamin ... be the first ingredient listed. Choose whole grain foods that contain one of the following ingredients first ...
Fine Grain Aluminum Superplasticity
1980-02-01
Continua on ravaraa sida H nacaaaary and identify by block numbar) Superplastic aluminum, Superplasticity, Superplastic forming. High strength aluminum...size. The presence of precipitate particles also acts to impede grain boundary migration during recrystallization, further aiding in maintaining a
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.)
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.)
On Interpolation Functions of the Generalized Twisted (h,q-Euler Polynomials
Directory of Open Access Journals (Sweden)
Kyoung Ho Park
2009-01-01
Full Text Available The aim of this paper is to construct p-adic twisted two-variable Euler-(h,q-L-functions, which interpolate generalized twisted (h,q-Euler polynomials at negative integers. In this paper, we treat twisted (h,q-Euler numbers and polynomials associated with p-adic invariant integral on ℤp. We will construct two-variable twisted (h,q-Euler-zeta function and two-variable (h,q-L-function in Complex s-plane.
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
2014-05-01
complexion transitions occur often in doped titanates, such as BaTiO3 and SrTiO3, and have been utilized to tailor microstructural develop- ment [275,276...Cantwell et al. / Acta Materialia 62 (2014) 1–48 Despite decades of research, efforts to identify grain boundary complexion transitions in pure metals via...evidence suggesting grain boundary complexion transitions in pure metals has existed for decades. For example, researchers have reported anomalies and
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.
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.
Higher twist analysis of the proton g1 structure function
International Nuclear Information System (INIS)
We perform a global analysis of all available spin-dependent proton structure function data, covering a large range of Q 2 , 1= 2 = 2 , and calculate the lowest moment of the g 1 structure function as a function of Q 2 . From the Q 2 dependence of the lowest moment we extract matrix elements of twist-4 operators, and determine the color electric and magnetic polarizabilities of the proton to be χ E =0.026+/-0.015(stat)+/- 0.024 0.021 (sys) and χ B =-0.013-bar 0.007(stat)-bar 0.012 0.010 (sys), respectively
Diffractive excitation of heavy flavors: Leading twist mechanisms
International Nuclear Information System (INIS)
Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan; Tarasov, A. V.
2007-01-01
Diffractive production of heavy flavors is calculated within the light-cone dipole approach. Novel leading twist mechanisms are proposed, which involve both short and long transverse distances inside the incoming hadron. Nevertheless, the diffractive cross section turns out to be sensitive to the primordial transverse momenta of projectile gluons, rather than to the hadronic size. Our calculations agree with the available data for diffractive production of charm and beauty, and with the observed weak variation of the diffraction-to-inclusive cross section ratios as function of the hard scale
Stretching, twisting and supercoiling in short, single DNA molecules
Lam, Pui-Man; Zhen, Yi
2018-02-01
We had combined the Neukirch-Marko model that describes the extension, torque and supercoiling in single, stretched and twisted DNA of infinite contour length, with a form of the free energy suggested by Sinha and Samuels to describe short DNA, with contour length only a few times the persistence length. We find that the free energy of the stretched but untwisted DNA, is significantly modified from its infinitely length value and this in turn modifies significantly the torque and supercoiling. We show that this is consistent with short DNA being more flexible than infinitely long DNA. We hope our results will stimulate experimental investigation of torque and supercoiling in short DNA.
Minimal regular models of quadratic twists of genus two curves
Sadek, Mohammad
2015-01-01
Let $K$ be a complete discrete valuation field with ring of integers $R$ and residue field $k$ of characteristic $p>2$. We assume moreover that $k$ is algebraically closed. Let $C$ be a smooth projective geometrically connected curve of genus $2$. If $K(\\sqrt{D})/K$ is a quadratic field extension of $K$ with associated character $\\chi$, then $C^{\\chi}$ will denote the quadratic twist of $C$ by $\\chi$. Given the minimal regular model $\\mathcal X$ of $C$ over $R$, we determine the minimal regul...
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.)
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.
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
PHASE STRUCTURE OF TWISTED EGUCHI-KAWAI MODEL.
Energy Technology Data Exchange (ETDEWEB)
ISHIKAWA,T.; AZEYANAGI, T.; HANADA, M.; HIRATA, T.
2007-07-30
We study the phase structure of the four-dimensional twisted Eguchi-Kawai model using numerical simulations. This model is an effective tool for studying SU(N) gauge theory in the large-N limit and provides a nonperturbative formulation of the gauge theory on noncommutative spaces. Recently it was found that its Z{sub n}{sup 4} symmetry, which is crucial for the validity of this model, can break spontaneously in the intermediate coupling region. We investigate in detail the symmetry breaking point from the weak coupling side. Our simulation results show that the continuum limit of this model cannot be taken.
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.
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.
grain-filling, chlorophyll content in relation with grain yield
African Journals Online (AJOL)
Prof. Adipala Ekwamu
number of fertile tillers nor number of grains per m². Grain weight is, however, reduced (Hochman,. 1982) due to a shortening of the grain filling period resulting from accelerated senescence. A long duration of grain filling is often an indicator of photosynthetic activity optimum, but a high velocity of filling is indicative of water.
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.
Twisting all the way: from algebras to morphisms and connections
Aschieri, Paolo
2012-01-01
Given a Hopf algebra H and an algebra A that is an H-module algebra we consider the category of left H-modules and A-bimodules, where morphisms are just right A-linear maps (not necessarily H-equivariant). Given a twist F of H we then quantize (deform) H to H^F, A to A_\\star and correspondingly the category of left H-modules and A-bimodules to the category of left H^F-modules and A_\\star-bimodules. If we consider a quasitriangular Hopf algebra H, a quasi-commutative algebra A and quasi-commutative A-bimodules, we can further construct and study tensor products over A of modules and of morphisms, and their twist quantization. This study leads to the definition of arbitrary (i.e., not necessarily H-equivariant) connections on quasi-commutative A-bimodules, to extend these connections to tensor product modules and to quantize them to A_\\star-bimodule connections. Their curvatures and those on tensor product modules are also determined.
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.))
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 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.
Actions for non-abelian twisted self-duality
Samtleben, Henning
2011-10-01
The dynamics of abelian vector and antisymmetric tensor gauge fields can be described in terms of twisted self-duality equations. These first-order equations relate the p-form fields to their dual forms by demanding that their respective field strengths are dual to each other. It is well known that such equations can be integrated to a local action that carries on equal footing the p-forms together with their duals and is manifestly duality invariant. Space-time covariance is no longer manifest but still present with a non-standard realization of space-time diffeomorphisms on the gauge fields. In this paper, we give a non-abelian generalization of this first-order action by gauging part of its global symmetries. The resulting field equations are non-abelian versions of the twisted self-duality equations. A key element in the construction is the introduction of proper couplings to higher-rank tensor fields. We discuss possible applications (to Yang-Mills and supergravity theories) and comment on the relation to previous no-go theorems.
NGC 5626: a massive fast rotator with a twist
Viaene, S.; Sarzi, M.; Baes, M.; Puerari, I.
2018-02-01
We present a kinematic analysis of the dust-lane elliptical NGC 5626 based on MUSE observations. These data allow us to robustly classify this galaxy as a fast rotator and to infer a virial mass of 1011.7 M⊙, making it one of the most massive fast rotators known. In addition, the depth and extent of the MUSE data reveal a strong kinematic twist in the stellar velocity field (by up to 45° beyond 1.5Re). A comparison with the ATLAS3D sample underlines the rareness of this system, although we show that such a large-scale kinematic twist could have been missed by the ATLAS3D data due to the limited spatial sampling of this survey (typically extending to 0.6Re for massive early-type galaxies). MUSE thus has the potential to unveil more examples of this type of galaxies. We discuss the environment and possible formation history of NGC 5626 and finally argue how a merger between the Milky Way and Andromeda could produce a galaxy of the same class as NGC 5626.
Exact zero vacuum energy in twisted SU(N) principal chiral field
Energy Technology Data Exchange (ETDEWEB)
Leurent, Sebastien [Univ. de Bourgogne Franche-Comte, Dijon (France). Inst. de Mathematique de Bourgogne; Sobko, Evgeny [DESY, Hamburg (Germany). Theory Group
2015-11-15
We present a finite set of equations for twisted PCF model. At the special twist in the root of unity we demonstrate that the vacuum energy is exactly zero at any size L. Also in SU(2) case we numerically calculate the energy of the single particle state with zero rapidity, as a function of L.
Lee, Hong-Jen; Li, Chien-Feng; Ruan, Diane; Powers, Scott; Thompson, Patricia A; Frohman, Michael A; Chan, Chia-Hsin
2016-09-15
Twist has been shown to cause treatment failure, cancer progression, and cancer-related death. However, strategies that directly target Twist are not yet conceivable. Here we reveal that K63-linked ubiquitination is a crucial regulatory mechanism for Twist activation. Through an E3 ligase screen and biochemical studies, we unexpectedly identified that RNF8 functions as a direct Twist activator by triggering K63-linked ubiquitination of Twist. RNF8-promoted Twist ubiquitination is required for Twist localization to the nucleus for subsequent EMT and CSC functions, thereby conferring chemoresistance. Our histological analyses showed that RNF8 expression is upregulated and correlated with disease progression, EMT features, and poor patient survival in breast cancer. Moreover, RNF8 regulates cancer cell migration and invasion and cancer metastasis, recapitulating the effect of Twist. Together, our findings reveal a previously unrecognized tumor-promoting function of RNF8 and provide evidence that targeting RNF8 is an appealing strategy to tackle tumor aggressiveness and treatment resistance. Copyright © 2016 Elsevier Inc. All rights reserved.
A laser speckle sensor to measure the distribution of static torsion angles of twisted targets
DEFF Research Database (Denmark)
Rose, B.; Imam, H.; Hanson, Steen Grüner
1998-01-01
. A cylindrical lens serves to image the closely spaced lateral positions of the target along the twist axis onto corresponding lines of the two dimensional image sensor. Thus, every single line of the image sensor measures the torsion angle of the corresponding surface position along the twist axis of the target...
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
Oh, Bo Young; Kim, So-Young; Lee, Yeo Song; Hong, Hye Kyung; Kim, Tae Won; Kim, Seok Hyung; Lee, Woo Yong; Cho, Yong Beom
2016-08-30
Colorectal cancer (CRC) with microsatellite instability (MSI) may exhibit impaired epithelial-mesenchymal transition (EMT), but little is known about the underlying mechanisms of this phenomenon. In this study, we investigated the role of Twist1 and its downstream signaling cascades in EMT induction according to MSI status. To investigate the effects of Twist1 on EMT induction according to MSI status, MSS LS513 and MSI LoVo colon cancer cell lines, which overexpress human Twist1, were generated. Twist1-induced EMT and its downstream signaling pathways were evaluated via in vitro and in vivo experiments. We found that Twist1 induced EMT markers and stem cell-like characteristics via AKT signaling pathways. Twist1 induced activation of AKT and suppression of glycogen synthase kinase (GSK)-3β, which resulted in the activation of β-catenin, increasing CD44 expression. In addition, Twist1 activated the AKT-induced NF-κB pathway, increasing CD44 and CD166 expression. Activation of both the AKT/GSK-3β/β-catenin and AKT/NF-κB pathways occurred in MSS LS513 cells, while only the AKT/GSK-3β/β-catenin pathway was activated in MSI LoVo cells. In conclusion, Twist1 induces stem cell-like characteristics in colon cancer cell lines related to EMT via AKT signaling pathways, and those pathways depend on MSI status.
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
Using Pretwist to Reduce Power Loss of Bend-Twist Coupled Blades
DEFF Research Database (Denmark)
Stäblein, Alexander; Tibaldi, Carlo; Hansen, Morten Hartvig
2016-01-01
Bend-twist coupling of wind turbine blades is known as a means to reduce the structural loads of the turbine. While the load reduction is desirable, bend-twist coupling also leads to a decrease in the annual energy production of the turbine. The reduction is mainly related to a no longer optimal...
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...
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 d...
Two-electron Oxidation of a Twisted Non Anti-aromatic 40π ...
Indian Academy of Sciences (India)
PRACHI GUPTA, SANTOSH P PANCHAL and VENKATARAMANARAO G ANAND. ∗. Department of Chemistry ... synthesis of the first twisted 40π expanded isophlorin and also its two-electron oxidation to a 38π dication. It sustains the twisted .... Tanaka T, Aratani N, Lim J M, Kim K S, Kim D and. Osuka A 2011 Chem. Sci.
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.
Twisted acceleration-enlarged Newton-Hooke space-times and conservative force terms
Daszkiewicz, Marcin
2011-01-01
There are analyzed two classical systems defined on twist-deformed acceleration-enlarged Newton-Hooke space-times - nonrelativistic particle moving in constant field force $\\vec{F}$ and harmonic oscillator model. It is demonstrated that only in the case of canonical twist deformation the force terms generated by space-time noncommutativity remain conservative for both models.
Effect of twist on single-mode fiber-optic 3 × 3 couplers
Chen, Dandan; Ji, Minning; Peng, Lei
2018-01-01
In the fabricating process of a 3 × 3 fused tapered coupler, the three fibers are usually twisted to be close-contact. The effect of twist on 3 × 3 fused tapered couplers is investigated in this paper. It is found that though a linear 3 × 3 coupler may realize equal power splitting ratio theoretically by twisting a special angle, it is hard to be fabricated actually because the twist angle and the coupler's length must be determined in advance. While an equilateral 3 × 3 coupler can not only realize approximate equal power splitting ratio theoretically but can also be fabricated just by controlling the elongation length. The effect of twist on the equilateral 3 × 3 coupler lies in the relationship between the equal ratio error and the twist angle. The more the twist angle is, the larger the equal ratio error may be. The twist angle usually should be no larger than 90° on one coupling period length in order to keep the equal ratio error small enough. The simulation results agree well with the experimental data.
Two new twisted helical nickel(II) and cobalt(III) octahedral monomer ...
Indian Academy of Sciences (India)
two complexes are isostructural with octahedral coordination environment exhibiting helical twist topology. They also display strong H-bonding as well as CH-π interactions to generate 1D chain. Keywords. Coordination chemistry; nickel(II); cobalt(III); Schiff base; twisted helicity; supramolecular interactions. 1. Introduction.
Radiation disinfestation of grain
International Nuclear Information System (INIS)
1962-01-01
A panel was convened by the International Atomic Energy Agency to consider ways of applying radiation to grain handling and insect control, and to make recommendations on the advisability and nature of any future action in this field. Among other subjects, the panel discussed the use of electron accelerators and gamma radiation for grain disinfestation as well as problems of radiation entomology and wholesomeness of irradiated grain. After reviewing the present state of knowledge regarding radiation disinfestation of grain, the experts agreed that pilot plant operations be initiated as soon as practicable in order to evaluate the use of irradiation plants under practical conditions in their entomological, engineering and economic aspects. They recommended that research effort be directed towards solving certain fundamental problems related to the proposed pilot plant projects; such as rapid methods for differentiation between sterile insects and normal ones; study of the metabolism of irradiated immature stages of insects in relation to the heating of treated grain; research into possible induction of radiation resistance; irradiation susceptibility of insects which show resistance to conventional insecticides; and study of methods of sensitizing insects to irradiation damage. It was also pointed out that the distribution of irradiated food for human consumption was controlled in most countries under present legislative procedures, and no country had yet approved radiation treatment of cereals. The experts recommended that countries in a position to submit evidence to their appropriate authorities regarding the wholesomeness of irradiated cereals should be encouraged to do so as soon as possible. Regarding the engineering aspects of irradiation pilot plant projects, the experts noted that the process could be automated and operated safely. Electron accelerators and cobalt sources could be used for all the throughput rates utilized in most conventional grain
Computerized radioautographic grain counting
International Nuclear Information System (INIS)
McKanna, J.A.; Casagrande, V.A.
1985-01-01
In recent years, radiolabeling techniques have become fundamental assays in physiology and biochemistry experiments. They also have assumed increasingly important roles in morphologic studies. Characteristically, radioautographic analysis of structure has been qualitative rather than quantitative, however, microcomputers have opened the door to several methods for quantifying grain counts and density. The overall goal of this chapter is to describe grain counting using the Bioquant, an image analysis package based originally on the Apple II+, and now available for several popular microcomputers. The authors discuss their image analysis procedures by applying them to a study of development in the central nervous system
Koike, Yuji; Pitonyak, Daniel; Yoshida, Shinsuke
2016-08-01
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 → → h X. 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.
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.
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.
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.
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.
International Nuclear Information System (INIS)
Khan, Ziauddin; Kundu, Ananya; Pradhan, Subrata
2013-01-01
Critical current (I c ) characteristics of 2G YBCO superconducting tape under the influence of twisting moment was experimentally investigated at varying current ramp rates in the self-field. Under a uniform twist, the degradation in the current-carrying capacity of YBCO tape up to 30% was observed at 77 K. The degradation is largely attributed to the shear stress and torsional shear strain resulting from the twisting. The superconductor to resistive transition index, n, is also found to behave in an identical manner with increase in the twisting. Finite element analysis (FEA) of the tape in the experimental configuration with twisting moment being applied on to it has been carried out in COMSOL. The torsional strain calculated analytically as per the experimental configuration matches closely with that of FEA results, which shows that the critical current degradation is a function of strain. (author)
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.
Monte Carlo simulations of segregation at [001] twist boundaries in a Pt(Au) alloy-II
International Nuclear Information System (INIS)
Seki, A.; Seidman, D.N.; Oh, Y.
1991-01-01
This paper reports on a three dimensional plot of the density of Au atoms versus the position which coordinates for the (002) planes, immediately adjacent to the interface, for a θ = 5 degrees [001] twist boundary, suggests the presence of a hill-and-valley structure in the Au segregation behavior at 850 K. The valleys correspond to the regions of good atomic fit between the regions of misfit; the hills correspond to the cores of the pairs of orthogonal primary grain boundary dislocations. A model for the Monte Carlo simulations is developed that leads to a linear expression for S aver containing a core segregation factor (S core ). For this model S core a single Arrhenius plot and the Gibbs free binding energy of a Au atom to the cores of the primary grain boundary dislocations extracted; the binding enthalpy and entropy of segregation are 0.095 ±0.01 eV and K B (0.49 ± 0.19) respectively
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.
Simulating grain size estimation
Czech Academy of Sciences Publication Activity Database
Saxl, Ivan; Sülleiová, K.; Ponížil, P.
2001-01-01
Roč. 39, č. 6 (2001), s. 396-409 ISSN 0023-432X R&D Projects: GA ČR GA201/99/0269 Keywords : grain size estimation% ASTM standards%Voronoi tessellations Subject RIV: BE - Theoretical Physics Impact factor: 0.343, year: 2001
Interstellar grain surface chemistry
International Nuclear Information System (INIS)
Tielens, A.G.G.M.
1989-01-01
Theoretical calculations, laboratory studies, and observations of interstellar icy grain mantles are reviewed. The emphasis is on recent ground-based observations of the interstellar 2167 cm -1 (4.67μm) band and air-borne studies of the interstellar 1665 and 1460 cm -1 (6.0 and 6.85μm) bands. From a comparison with laboratory studies it is concluded that interstellar icy gain mantles consist mainly of H 2 O, CH 3 OH and CO in an approximate ratio of 100:50:5. Traces of other molecules have also been detected. Evidence for the presence of a separate, more inert, grain mantle component, perhaps consisting mainly of solid CO, will also be presented. Theoretical calculations of the composition of interstellar icy gain mantles are confronted with observational data and the shortcomings of the models are pointed out. Finally, the evolution of icy grain mantles under UV irradiation and their possible interrelationship with an organic grain component observed in the diffuse interstellar medium are discussed
African Journals Online (AJOL)
have stable, not too short crop duration with ... Ndiaye is located in the. Costal Delta region of Senegal. The climate of the Delta is characterized by a wet season from July to October with approximately. 200 mm of ..... Analysis of variance of the effect of site and season on maturity, grain yield and plant height of 16 rice.
Grain Boundary Segregation in Metals
Lejcek, Pavel
2010-01-01
Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.
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
Restriction of molecular twisting on a gold nanoparticle surface.
Debnath, Tushar; Dana, Jayanta; Maity, Partha; Lobo, Hyacintha; Shankarling, Ganapati S; Ghosh, Hirendra N
2015-04-07
To understand the photophysical properties of intramolecular charge transfer (ICT) and twisted intramolecular charge transfer (TICT) states on a gold nanoparticle (Au NP) surface, we have designed and synthesized a new coumarin molecule (C3) that exists both as ICT and TICT states in its excited state in a polar environment. On a Au NP surface, an excited C3 molecule only exists as an ICT state owing to restricted molecular rotation of a diethylamino group; as a result, no conversion from the ICT to TICT state was observed. Selection of the preferential state of a molecule with dual emitting states can be helpful for selected biological applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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.
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.)
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
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.
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
Surveying 4d SCFTs twisted on Riemann surfaces
Amariti, Antonio; Cassia, Luca; Penati, Silvia
2017-06-01
Within the framework of four dimensional conformal supergravity we consider N=1,2,3,4 supersymmetric theories generally twisted along the abelian subgroups of the R-symmetry and possibly other global symmetry groups. Upon compactification on constant curvature Riemann surfaces with arbitrary genus we provide an extensive classification of the resulting two dimensional theories according to the amount of supersymmetry that is preserved. Exploiting the c-extremization prescription introduced in arXiv:1211.4030 we develop a general procedure to obtain the central charge for 2d N=(0,2) theories and the expression of the corresponding R-current in terms of the original 4d one and its mixing with the other abelian global currents.
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.
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.
Electrostatic twisted modes in multi-component dusty plasmas
International Nuclear Information System (INIS)
Ayub, M. K.; Ali, S.; Ikram, M.
2016-01-01
Various electrostatic twisted modes are re-investigated with finite orbital angular momentum in an unmagnetized collisionless multi-component dusty plasma, consisting of positive/negative charged dust particles, ions, and electrons. For this purpose, hydrodynamical equations are employed to obtain paraxial equations in terms of density perturbations, while assuming the Gaussian and Laguerre-Gaussian (LG) beam solutions. Specifically, approximated solutions for potential problem are studied by using the paraxial approximation and expressed the electric field components in terms of LG functions. The energy fluxes associated with these modes are computed and corresponding expressions for orbital angular momenta are derived. Numerical analyses reveal that radial/angular mode numbers as well as dust number density and dust charging states strongly modify the LG potential profiles attributed to different electrostatic modes. Our results are important for understanding particle transport and energy transfer due to wave excitations in multi-component dusty plasmas
String Theory, Strongly Correlated Systems, and Duality Twists
Torres Chicon, Nesty Ray
In the first part of this dissertation (Chapter 1), I present a construction of a six dimensional (2,0)-theory model that describes the dynamics of the Fractional Quantum Hall Effect (FQHE). The FQHE appears as part of the low energy description of the Coulomb branch of the A1 (2,0)-theory formulated on a geometry (S 1 x R2)/Zk. At low-energy, the configuration is described in terms of a 4+1D supersymmetric Yang-Mills (SYM) theory on a cone (R2/Z k) with additional 2+1D degrees of freedom at the tip of the cone that include fractionally charged particles. These fractionally charged "quasi-particles" are BPS strings of the (2,0)-theory wrapped on short cycles. In this framework, a W-boson can be modeled as a bound state of k quasi-particles, which can be used to understand the dynamics of the FQHE. In the second part of this dissertation (Chapters 2-3), I investigate the N=4 SYM theory compactified on a circle, with a varying coupling constant (Janus configuration) and an S-duality twist. I relate this setup to a three dimensional topological theory and to a dual string theory. The equality of these descriptions is exhibited by matching the operator algebra, and the dimensions of the Hilbert space. Additionally, this dissertation addresses a classic result in number theory, called quadratic reciprocity, using string theory language. I present a proof that quadratic reciprocity is a direct consequence of T-duality of Type-II string theory. This is demonstrated by analyzing a partition function of abelian N=4 SYM theory on a certain supersymmetry-preserving four-manifold with variable coupling constant and a SL(2,Z)-duality twist.
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.
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.
Twisting integrin receptors increases endothelin-1 gene expression in endothelial cells
Chen, J.; Fabry, B.; Schiffrin, E. L.; Wang, N.; Ingber, D. E. (Principal Investigator)
2001-01-01
A magnetic twisting stimulator was developed based on the previously published technique of magnetic twisting cytometry. Using ligand-coated ferromagnetic microbeads, this device can apply mechanical stresses with varying amplitudes, duration, frequencies, and waveforms to specific cell surface receptors. Biochemical and biological responses of the cells to the mechanical stimulation can be assayed. Twisting integrin receptors with RGD (Arg-Gly-Asp)-containing peptide-coated beads increased endothelin-1 (ET-1) gene expression by >100%. In contrast, twisting scavenger receptors with acetylated low-density lipoprotein-coated beads or twisting HLA antigen with anti-HLA antibody-coated beads did not lead to alterations in ET-1 gene expression. In situ hybridization showed that the increase in ET-1 mRNA was localized in the cells that were stressed with the RGD-coated beads. Blocking stretch-activated ion channels with gadolinium, chelating Ca2+ with EGTA, or inhibiting tyrosine phosphorylation with genistein abolished twist-induced ET-1 mRNA elevation. Abolishing cytoskeletal tension with an inhibitor of the myosin ATPase, with an inhibitor of myosin light chain kinase, or with an actin microfilament disrupter blocked twisted-induced increases in ET-1 expression. Our results are consistent with the hypothesis that the molecular structural linkage of integrin-cytoskeleton is an important pathway for stress-induced ET-1 gene expression.
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.
Sausage MHD Waves in Incompressible Flux Tubes with Twisted Magnetic Fields
Erdélyi, Robert; Fedun, Viktor
2006-10-01
Twisted magnetic flux tubes are of considerable interest because of their natural occurrence from the Sun’s interior, throughout the solar atmosphere and interplanetary space up to a wide range of applicabilities to astrophysical plasmas. The aim of the present work is to obtain analytically a dispersion equation of linear wave propagation in twisted incompressible cylindrical magnetic waveguides and find appropriate solutions for surface, body and pseudobody sausage modes (i.e. m = 0) of a twisted magnetic flux tube embedded in an incompressible but also magnetically twisted plasma. Asymptotic solutions are derived in long- and short-wavelength approximations. General solutions of the dispersion equation for intermediate wavelengths are obtained numerically. We found, that in case of a constant, but non-zero azimuthal component of the equilibrium magnetic field outside the flux tube the index ν of Bessel functions in the dispersion relation is not integer any more in general. This gives rise to a rich mode-structure of degenerated magneto-acoustic waves in solar flux tubes. In a particular case of a uniform magnetic twist the total pressure is found to be constant across the boundary of the flux tube. Finally, the effect of magnetic twist on oscillation periods is estimated under solar atmospheric conditions. It was found that a magnetic twist will increase, in general, the periods of waves approximately by a few percent when compared to their untwisted counterparts.
A Computational Study of BVI Noise Reduction Using Active Twist Control
Fogarty, David E.; Wilbur, Matthew L.; Sekula, Martin K.
2010-01-01
The results of a computational study examining the effects of active-twist control on blade-vortex interaction (BVI) noise using the Apache Active Twist Rotor are presented. The primary goal of this activity is to reduce BVI noise during a low-speed descent flight condition using active-twist control. Rotor aeroelastic behavior was modeled using the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics code and the rotor noise was predicted using the acoustics code PSU-WOPWOP. The accuracy of the analysis was validated through comparisons with experimental acoustic data for the first generation Active Twist Rotor at an advance ratio of mu=0.14. The application of active-twist to the main rotor blade system consisted of harmonic actuation frequencies ranging from 2P to 5P, control phase angles from 0' to 360 , and tip-twist amplitudes ranging from 0.5 to 4.0 . The acoustic analysis was conducted for a single low-speed flight condition of advance ratio =0.14 and shaft angle-of-attack, c^=+6 , with BVI noise levels predicted on a flat plane of observers located 1.1 rotor diameters beneath the rotor. The results indicated reductions of up to 11dB in BVI noise using 1.25 tip-twist amplitude with negligible effects on 4P vertical hub shear.
Hydrodynamic characteristics of X-Twisted rudder for large container carriers
Directory of Open Access Journals (Sweden)
Kyoungsoo Ahn
2012-09-01
Full Text Available This paper shows the numerical and experimental results about the hydrodynamic characteristics of X-Twisted rudders having continuous twist of the leading edge along the span. All the results were compared with those of the semi-balanced rudder. Calculation through the Reynolds-Averaged Navier-Stokes Equation (RANSE code with propeller sliding meshes shows large inflow angle and fast inflow velocity in the vicinity of ±0.7 R from the shaft center, so it may cause cavitation. Also, X-Twisted rudder has relatively small inflow angles along the rudder span compared with semi-balanced rudder. For the performance validation, rudders for two large container carriers were designed and tested. Cavitation tests at the medium sized cavitation tunnel with respect to the rudder types and twisted angles showed the effectiveness of twist on cavitation and the tendency according to the twist. And the resistance, self-propulsion and manoeuvring tests were also carried out at the towing tank. As a result, in the case of X-Twisted rudder, ship speed was improved with good manoeuvring performance. Especially, it was found out that manoeuvring performance between port and starboard was well balanced compared with semi-balanced rudders.
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.
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.
Twist1 transcriptional targets in the developing atrio-ventricular canal of the mouse.
Directory of Open Access Journals (Sweden)
Pavle Vrljicak
Full Text Available Malformations of the cardiovascular system are the most common type of birth defect in humans, frequently affecting the formation of valves and septa. During heart valve and septa formation, cells from the atrio-ventricular canal (AVC and outflow tract (OFT regions of the heart undergo an epithelial-to-mesenchymal transformation (EMT and invade the underlying extracellular matrix to give rise to endocardial cushions. Subsequent maturation of newly formed mesenchyme cells leads to thin stress-resistant leaflets. TWIST1 is a basic helix-loop-helix transcription factor expressed in newly formed mesenchyme cells of the AVC and OFT that has been shown to play roles in cell survival, cell proliferation and differentiation. However, the downstream targets of TWIST1 during heart valve formation remain unclear. To identify genes important for heart valve development downstream of TWIST1, we performed global gene expression profiling of AVC, OFT, atria and ventricles of the embryonic day 10.5 mouse heart by tag-sequencing (Tag-seq. Using this resource we identified a novel set of 939 genes, including 123 regulators of transcription, enriched in the valve forming regions of the heart. We compared these genes to a Tag-seq library from the Twist1 null developing valves revealing significant gene expression changes. These changes were consistent with a role of TWIST1 in controlling differentiation of mesenchymal cells following their transformation from endothelium in the mouse. To study the role of TWIST1 at the DNA level we performed chromatin immunoprecipitation and identified novel direct targets of TWIST1 in the developing heart valves. Our findings support a role for TWIST1 in the differentiation of AVC mesenchyme post-EMT in the mouse, and suggest that TWIST1 can exert its function by direct DNA binding to activate valve specific gene expression.
Twist1 transcriptional targets in the developing atrio-ventricular canal of the mouse.
Vrljicak, Pavle; Cullum, Rebecca; Xu, Eric; Chang, Alex C Y; Wederell, Elizabeth D; Bilenky, Mikhail; Jones, Steven J M; Marra, Marco A; Karsan, Aly; Hoodless, Pamela A
2012-01-01
Malformations of the cardiovascular system are the most common type of birth defect in humans, frequently affecting the formation of valves and septa. During heart valve and septa formation, cells from the atrio-ventricular canal (AVC) and outflow tract (OFT) regions of the heart undergo an epithelial-to-mesenchymal transformation (EMT) and invade the underlying extracellular matrix to give rise to endocardial cushions. Subsequent maturation of newly formed mesenchyme cells leads to thin stress-resistant leaflets. TWIST1 is a basic helix-loop-helix transcription factor expressed in newly formed mesenchyme cells of the AVC and OFT that has been shown to play roles in cell survival, cell proliferation and differentiation. However, the downstream targets of TWIST1 during heart valve formation remain unclear. To identify genes important for heart valve development downstream of TWIST1, we performed global gene expression profiling of AVC, OFT, atria and ventricles of the embryonic day 10.5 mouse heart by tag-sequencing (Tag-seq). Using this resource we identified a novel set of 939 genes, including 123 regulators of transcription, enriched in the valve forming regions of the heart. We compared these genes to a Tag-seq library from the Twist1 null developing valves revealing significant gene expression changes. These changes were consistent with a role of TWIST1 in controlling differentiation of mesenchymal cells following their transformation from endothelium in the mouse. To study the role of TWIST1 at the DNA level we performed chromatin immunoprecipitation and identified novel direct targets of TWIST1 in the developing heart valves. Our findings support a role for TWIST1 in the differentiation of AVC mesenchyme post-EMT in the mouse, and suggest that TWIST1 can exert its function by direct DNA binding to activate valve specific gene expression.
Biaxial magnetic grain alignment
International Nuclear Information System (INIS)
Staines, M.; Genoud, J.-Y.; Mawdsley, A.; Manojlovic, V.
2000-01-01
Full text: We describe a dynamic magnetic grain alignment technique which can be used to produce YBCO thick films with a high degree of biaxial texture. The technique is, however, generally applicable to preparing ceramics or composite materials from granular materials with orthorhombic or lower crystal symmetry and is therefore not restricted to superconducting applications. Because magnetic alignment is a bulk effect, textured substrates are not required, unlike epitaxial coated tape processes such as RABiTS. We have used the technique to produce thick films of Y-247 on untextured silver substrates. After processing to Y-123 the films show a clear enhancement of critical current density relative to identically prepared untextured or uniaxially textured samples. We describe procedures for preparing materials using magnetic biaxial grain alignment with the emphasis on alignment in epoxy, which can give extremely high texture. X-ray rocking curves with FWHM of as little as 1-2 degrees have been measured
Energy Technology Data Exchange (ETDEWEB)
The study has concentrated upon a detailed examination of all considerations involved in the production, use, and marketing of ethyl alcohol (ethanol) as produced from the fermentation of agricultural grains. Each parameter was examined in the light of current energy markets and trends; new sources and technological, and processes for fermentation, the capability of the agricultural industry to support fermentation demand; the optimizaton of value of agricultural crops; and the efficiencies of combining related industries. Ahydrous (200 proof) ethanol makes an excellent blending component for all present automotive fuels and an excellent octane additive for unleaded fuels in proportions up to 35% without requiring modifications to current engines. There is no difference between ethanol produced by fermentation and ethanol produced synthetically from petroleum. The decision to produce ethanol one way or the other is purely economic. The agricultural industry can support a major expansion in the fermentation industry. The residue (distillers grains) from the fermentation of corn for ethanol is an excellent and economical feed for livestock and poultry. A reliable supply of distillers grain can assist in making the large beef feedlot operations more economically viable. The source materials, fuels, products and by-products of an ethanol plant, beef feedlot, gas biodigester plant, municipal waste recovery plant and a steam generated electrical plant are interrelated and mutually beneficial for energy efficiencies and economic gains when co-located. The study concludes that the establishment of such agricultural- environment industrial energy complexes, would provide a broad range of significant benefits to Indiana.
Energy Technology Data Exchange (ETDEWEB)
The study has concentrated upon a detailed examination of all considerations involved in the production, use, and marketing of ethyl alcohol (Ethanol) as produced from the fermentation of agricultural grains. Each parameter was examined in the light of current energy markets and trends; new sources and technological, and processes for fermentation, the capability of the agricultural industry to support fermentaton demand; the optimization of value of agricultureal crops; and the efficiencies of combining related industries. Anhydrous (200 proof) ethanol makes an excellent blending component for all present automotive fuels and an excellent octane additive for unleaded fuels in proportions up to 35% without requiring modifications to current engines. There is no difference between ethanol produced by fermentation and ethanol produced synthetically from petroleum. The decision to produce ethanol one way or the other is purely economic. The agricultural industry can support a major expansion in the fermentation industry. The residue (distillers grains) from the fermentation of corn for ethanol is an excellent and economical feed for livestock and poultry. A reliable supply of distillers grains can assist in making the large beef feedlot operations more economically viable. The source materials, fuels, products and by-products of an ethanol plant, beef feedlot, gas biodigester plant, municipal waste recovery plant and a steam generated electrical plant are interrelated and mutually beneficial for energy efficiencies and economic gains when co-located. The study concludes that the establishment of such agricultural-environment industrial energy complexes, would provide a broad range of significant benefits to Indiana.
International Nuclear Information System (INIS)
Trisviatski, L.A.
1973-01-01
First the importance of cereals collected in the S.S.S.R., the reason why the government had to put in practice a storage chain, composed of large capacity store houses (200 000 metric tonnes, or more) is reminded. When climatic conditions result in wet harvested grains, cereals are dried either in state enterprise dryers (32 to 50 tonnes/hour) or in kolkhozes' dryers (2 to 16 tonnes/hour). A new type of drying with recycling, has been developped, economizing 10 to 15 p. 100. Then the possibilities offered by the technique of partial drying of very wet grains are studied and the preservation processes using fresh ventilation, or hot ventilation with drying effect are described. The question of silage of wet grains destined to animal consumption is then examined as well as preservation by sodium pyrosulfide; the use of propionic acid, little developped in SSSR, is studied now, just as storage with inert gas. The struggle technics against insects, either with chemical agents, or with irradiation are described. Finally the modalities of technicians formation, specialized in preservation, are discussed [fr
Directory of Open Access Journals (Sweden)
P. Siricharuanun
2016-01-01
Full Text Available A second-order sliding mode control for chaotic synchronization with bounded disturbance is studied. A robust finite-time controller is designed based on super twisting algorithm which is a popular second-order sliding mode control technique. The proposed controller is designed by combining an adaptive law with super twisting algorithm. New results based on adaptive super twisting control for the synchronization of identical Qi three-dimensional four-wing chaotic system are presented. The finite-time convergence of synchronization is ensured by using Lyapunov stability theory. The simulations results show the usefulness of the developed control method.
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,...
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
Energy Technology Data Exchange (ETDEWEB)
Wilson, Joshua Lee [Univ. of Tennessee, Knoxville, TN (United States)
2008-12-01
A new class of accelerating structures employing a uniformly twisted waveguide is investigated. Twisted waveguides of various cross-sectional geometries are considered and analyzed. It is shown that such a twisted waveguide can support waves that travel at a speed slower than the speed of light c. The slow-wave properties of twisted structures are of interest because these slow-wave electromagnetic fields can be used in applications such as electron traveling wave tubes and linear particle accelerators. Since there is no exact closed form solution for the electromagnetic fields within a twisted waveguide or cavity, several previously proposed approximate methods are examined, and more effcient approaches are developed. It is found that the existing perturbation theory methods yield adequate results for slowly twisted structures; however, our efforts here are geared toward analyzing rapidly twisted structures using modifed finite difference methods specially suited for twisted structures. Although the method can handle general twisted structures, three particular cross sections are selected as representative cases for careful analysis. First, a slowly twisted rectangular cavity is analyzed as a reference case. This is because its shape is simple and perturbation theory already gives a good approximate solution for such slow twists rates. Secondly, a symmetrically notched circular cross section is investigated, since its longitudinal cross section is comparable to the well known disk-loaded cavity (used in many practical accelerator designs, including SLAC). Finally, a "dumbbell" shaped cross section is analyzed because of its similarity to the well-known TESLA-type accelerating cavity, which is of great importance because of its wide acceptance as a superconducting cavity. To validate the results of the developed theory and our extensive simulations, the newly developed numerical models are compared to commercial codes. Also, several prototypes are developed
Orbital angular momentum modes by twisting of a hollow core antiresonant fiber
DEFF Research Database (Denmark)
Stefani, Alessio; Kuhlmey, Boris T.; Fleming, Simon
2017-01-01
Generation and use of orbital angular momentum (OAM) of light is finding more and more interest in a wide variety of fields of photonics: communications, optical trapping, quantum optics, and many more [1]. In the investigation of such behavior, twisting of photonic crystal fibers shows interesting...... physical phenomena [2]. We previously reported the ability to create helical hollow fibers by mechanically twisting a tube lattice fiber made of polyurethane, the twist of which can be adjusted and reversed [3]. In this work we report how such deformation induces a mode transformation to an OAM mode...
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 sign......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....
Energy Technology Data Exchange (ETDEWEB)
Sugimoto, T.; Kobayashi, H.; Ishikawa, T.; Kamiya, T. [Kogakuin University, Tokyo (Japan); Niitsu, T.; Inoue, H. [Soka University, Tokyo (Japan)
1996-01-20
The permeate flux of a membrane module fitted with a twisted tape or static mixer was 4-7.7 times higher than that of a membrane module without any turbulent promoter. Use of a twisted tape or static mixer shortened separation time. The energy consumption per unit mass of permeate due to pressure drop in the membrane module with twisted tape or static mixer was 2-3 times higher than that in the membrane module without turbulent promoter. The permeate flux solved by introducing the value of mass transfer coefficient into the osmotic pressure model coincided well with experimental results, where the mass transfer coefficient was obtained by simulating experimental formula of heat transfer in a pipe fitted with a twisted tape or static mixer into a mass transfer correlation by the heat transfer-mass transfer analogy. The mass transfer coefficient in a membrane module with twisted tape or static mixer increased to about 4 to 8 times that of a membrane module without turbulent promoter. 7 refs., 10 figs.
A study was executed to determine the potential of storing farmers stock peanuts and shelled peanuts for crushing in hermetically sealed grain bags. The objectives of the study were to evaluate equipment for loading and unloading the grain bags, the capacity of the grain bags, and the changes in qu...
Gauged supergravities from twisted doubled tori and non-geometric string backgrounds
International Nuclear Information System (INIS)
Dall'Agata, Gianguido; Prezas, Nikolaos; Samtleben, Henning; Trigiante, Mario
2008-01-01
We propose a universal geometric formulation of gauged supergravity in terms of a twisted doubled torus. We focus on string theory (M-theory) reductions with generalized Scherk-Schwarz twists residing in the O(n,n) (E 7(7) ) duality group. The set of doubled geometric fluxes, associated with the duality twists and identified naturally with the embedding tensor of gauged supergravity, captures all known fluxes, i.e. physical form fluxes, ordinary geometric fluxes, as well as their non-geometric counterparts. Furthermore, we propose a prescription for obtaining the effective geometry embedded in the string theory twisted doubled torus or in the M-theory megatorus and apply it for several models of geometric and non-geometric flux compactifications
Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations
Energy Technology Data Exchange (ETDEWEB)
Nika, Denis L. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States); Cocemasov, Alexandr I. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Balandin, Alexander A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States)
2014-07-21
We have studied the phonon specific heat in single-layer, bilayer, and twisted bilayer graphene. The calculations were performed using the Born-von Karman model of lattice dynamics for intralayer atomic interactions and spherically symmetric interatomic potential for interlayer interactions. We found that at temperature T < 15 K, specific heat varies with temperature as T{sup n}, where n = 1 for graphene, n = 1.6 for bilayer graphene, and n = 1.3 for the twisted bilayer graphene. The phonon specific heat reveals an intriguing dependence on the twist angle in bilayer graphene, which is particularly pronounced at low temperature. The results suggest a possibility of phonon engineering of thermal properties of layered materials by twisting the atomic planes.
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.
Two-electron Oxidation of a Twisted Non Anti-aromatic 40π ...
Indian Academy of Sciences (India)
electron Oxidation of a Twisted Non Anti-aromatic 40π Expanded Isophlorin. PRACHI GUPTA SANTOSH P PANCHAL VENKATARAMANARAO G ANAND. Rapid Communication Volume 128 Issue 11 November 2016 pp 1703-1707 ...
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.)
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.)
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.
Innovation of Methods for Measurement and Modelling of Twisted Pair Parameters
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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.
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.
Twist-Bend Coupling and the Torsional Response of Double-Stranded DNA
Nomidis, Stefanos K.; Kriegel, Franziska; Vanderlinden, Willem; Lipfert, Jan; Carlon, Enrico
2017-05-01
Recent magnetic tweezers experiments have reported systematic deviations of the twist response of double-stranded DNA from the predictions of the twistable wormlike chain model. Here we show, by means of analytical results and computer simulations, that these discrepancies can be resolved if a coupling between twist and bend is introduced. We obtain an estimate of 40 ±10 nm for the twist-bend coupling constant. Our simulations are in good agreement with high-resolution, magnetic-tweezers torque data. Although the existence of twist-bend coupling was predicted long ago [J. Marko and E. Siggia, Macromolecules 27, 981 (1994), 10.1021/ma00082a015], its effects on the mechanical properties of DNA have been so far largely unexplored. We expect that this coupling plays an important role in several aspects of DNA statics and dynamics.
Tantsuõpetajate twist ja twin Taanis / Anu Sööt
Sööt, Anu, 1957-
2015-01-01
Taanis toimunud rahvusvahelisest tantsuhariduse kongressist, mille teema oli sel aastal „Twist ja Twin. Exploring Identities in Dance” („Pöörlemine ja ühendumine. Laiendades tantsu identiteeti”).
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.
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
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.
Alternative grains in nutrition
Directory of Open Access Journals (Sweden)
Jevcsák Sz.
2016-12-01
Full Text Available Many people suffer from gluten sensitivity or gluten intolerance. They have to avoid or limit their gluten intake. Sorghum and millet are gluten-free cereals, wherefore persons with gluten sensitivity or gluten intolerance could consume them. Moreover, they have a lot of positive effects due to their phenolic compounds as phenol acid or flavonoid. Antioxidant activity in sorghum is especially high in comparison with other cereals. Our aim was to compare literature data about the chemical compositions of sorghum and millet with other grains.
Twist Field as Three String Interaction Vertex in Light Cone String Field Theory
Kishimoto, Isao; Moriyama, Sanefumi; Teraguchi, Shunsuke
2006-01-01
It has been suggested that matrix string theory and light-cone string field theory are closely related. In this paper, we investigate the relation between the twist field, which represents string interactions in matrix string theory, and the three-string interaction vertex in light-cone string field theory carefully. We find that the three-string interaction vertex can reproduce some of the most important OPEs satisfied by the twist field.
Coupled CFD/CSD Computation of Airloads of an Active-Twist Rotor
Massey, Steven J.; Kreshock, Andrew R.; Sekula, Martin K
2013-01-01
An unsteady Reynolds averaged Navier-Stokes analysis loosely coupled with a comprehensive rotorcraft code for blade trim and aeroelastic effects is presented for a second-generation Active-Twist Rotor. Mesh and temporal sensitives of computed airloads are evaluated. In the final paper, computed airloads will be compared with wind tunnel data for the Active-Twist Rotor test that is currently underway.
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.
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.
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
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.)
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.)
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)
Twisted Acceleration-Enlarged Newton-Hooke Space-Times and Conservative Force Terms
International Nuclear Information System (INIS)
Daszkiewicz, M.
2011-01-01
There are analyzed two classical systems defined on twist-deformed acceleration-enlarged Newton-Hooke space-times - non-relativistic particle moving in constant field force ∼F and harmonic oscillator model. It is demonstrated that only in the case of canonical twist deformation the force terms generated by space-time non-commutativity remain conservative for both models. (author)
Low-Frequency Interlayer Raman Modes to Probe Interface of Twisted Bilayer MoS2.
Huang, Shengxi; Liang, Liangbo; Ling, Xi; Puretzky, Alexander A; Geohegan, David B; Sumpter, Bobby G; Kong, Jing; Meunier, Vincent; Dresselhaus, Mildred S
2016-02-10
van der Waals homo- and heterostructures assembled by stamping monolayers together present optoelectronic properties suitable for diverse applications. Understanding the details of the interlayer stacking and resulting coupling is crucial for tuning these properties. We investigated the low-frequency interlayer shear and breathing Raman modes (<50 cm(-1)) in twisted bilayer MoS2 by Raman spectroscopy and first-principles modeling. Twisting significantly alters the interlayer stacking and coupling, leading to notable frequency and intensity changes of low-frequency modes. The frequency variation can be up to 8 cm(-1) and the intensity can vary by a factor of ∼5 for twisting angles near 0° and 60°, where the stacking is a mixture of high-symmetry stacking patterns and is thus sensitive to twisting. For twisting angles between 20° and 40°, the interlayer coupling is nearly constant because the stacking results in mismatched lattices over the entire sample. It follows that the Raman signature is relatively uniform. Note that for some samples, multiple breathing mode peaks appear, indicating nonuniform coupling across the interface. In contrast to the low-frequency interlayer modes, high-frequency intralayer Raman modes are much less sensitive to interlayer stacking and coupling. This research demonstrates the effectiveness of low-frequency Raman modes for probing the interfacial coupling and environment of twisted bilayer MoS2 and potentially other two-dimensional materials and heterostructures.
Lattice formulation of 2D N = (2,2) SQCD and twisted supercharges
International Nuclear Information System (INIS)
Sugino, Fumihiko
2013-01-01
We discuss on two kinds of lattice formulation of two-dimensional N = (2, 2) supersymmetric QCD preserving one of its supercharges. The preserved supercharge is of the same form obtained by topological twist. One formulation is based on A model twist, and the other is based on B model twist. For the A model twist case, by employing the Ginsparg-Wilson operator, the lattice model can be constructed for general number of flavors of fundamental and anti-fundamental matter multiplets under the gauge group G = U(N) or SU(N). It preserves both of one supercharge (Q) and chiral flavor symmetry of matter multiplets. Furthermore, superpotential can be introduced with exact holomorphic or anti-holomorphic structure on lattice. For the B model twist case, the lattice action takes a simpler form compared with the A model twist case, because the admissibility condition is not required to the formulation. It can be applied to a restricted cases of G = U(N) and of fundamental matters or anti-fundamental matters only.
Reversal of helicoidal twist handedness near point defects of confined chiral liquid crystals.
Ackerman, Paul J; Smalyukh, Ivan I
2016-05-01
Handedness of the director twist in cholesteric liquid crystals is commonly assumed to be the same throughout the medium, determined solely by the chirality of constituent molecules or chiral additives, albeit distortions of the ground-state helicoidal configuration often arise due to the effects of confinement and external fields. We directly probe the twist directionality of liquid crystal director structures through experimental three-dimensional imaging and numerical minimization of the elastic free energy and show that spatially localized regions of handedness opposite to that of the chiral liquid crystal ground state can arise in the proximity of twisted-soliton-bound topological point defects. In chiral nematic liquid crystal confined to a film that has a thickness less than the cholesteric pitch and perpendicular surface boundary conditions, twisted solitonic structures embedded in a uniform unwound far-field background with chirality-matched handedness locally relieve confinement-imposed frustration and tend to be accompanied by point defects and smaller geometry-required, energetically costly regions of opposite twist handedness. We also describe a spatially localized structure, dubbed a "twistion," in which a twisted solitonic three-dimensional director configuration is accompanied by four point defects. We discuss how our findings may impinge on the stability of localized particlelike director field configurations in chiral and nonchiral liquid crystals.
Takagawa, Yoshitoki; Furukawa, Tetsuaki
2018-01-01
A sheathless system that inserts a catheter directly into the artery can reduce puncture site-related complications through a 2-Fr reduction of the outer diameter. However, the gap between the dilator and the guiding catheter of the sheathless system is larger than the gap between the dilator and sheath of the introducer system, resulting in stronger insertion resistance. A twisting method with rapid alternating rotation of a device to the left and right during insertion can reduce the insertion resistance. This method can be effective with the sheathless system which has a larger gap. To examine the effect of size reduction on the sheathless system and the effect of insertion resistance reduction using the twisting method, we developed an insertion simulator and compared insertion resistance to a 5-Fr sheath introducer and a 5-Fr sheathless system, with and without the twisting method. The insertion simulator pushed a sheath introducer or a sheathless system toward a mock artery consisted with a 5-mm urethane and a 1-mm rubber sheet by an electrical motor with or without twisting motion generated by a crank shaft. Insertion resistance during the penetration was measured by a tension meter. The insertion resistance was less with the 5-Fr sheathless system than with the 5-Fr sheath introducer. The resistance reduced further with use of twisting for both the sheathed and sheathless catheters. In conclusion, the experiment suggests the benefits of twisting insertion of a sheathless guiding catheter for reduction of puncture site-related complications.
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
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.
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.
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.
Twisted Soft Photon Hair Implants on Black Holes
Tamburini, Fabrizio; Laurentis, Mariafelicia; Licata, Ignazio; Thidé, Bo
2017-08-01
The Hawking-Perry-Strominger (HPS) work [1] states a new controversial idea about the black hole (BH) information paradox [2-5] where BHs maximally entropize and encode information in their event horizon area [6,7], with no "hair" were thought to reveal information outside but angular momentum, mass and electric charge only [8,9] in a unique quantum gravity (QG) vacuum state. This new idea invokes new conservation laws involving gravitation and electromagnetism [10,11], to generate different QG vacua and preserve more information in hair implants. In the context of black holes and the HPS proposal we find that BH photon hair implants can be spatially shaped ad hoc and encode structured and densely organized information on the event horizon involving novel aspect in the discussion a particular aspect of EM fields, namely the spatial information of the field associated to its orbital angular momentum. BHs can have "curly", twisted, soft-hair implants with vorticity where structured information is holographically encoded in the event horizon in an organized way.
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
Quantum spin Hall effect in twisted bilayer graphene
Finocchiaro, F.; Guinea, F.; San-Jose, P.
2017-06-01
Motivated by a recent experiment (Sanchez-Yamagishi et al 2016 Nat. Nanotechnol. 214) reporting evidence of helical spin-polarized edge states in layer-biased twisted bilayer graphene under a magnetic flux, we study the possibility of stabilising a quantum spin Hall (QSH) phase in such a system, without Zeeman or spin-orbit couplings, and with a QSH gap induced instead by electronic interactions. We analyse how magnetic flux, electric field, interlayer rotation angle, and interactions (treated at a mean field level) combine to produce a pseudo-QSH with broken time-reversal symmetry, and spin-polarized helical edge states. The effect is a consequence of a robust interaction-induced ferrimagnetic ordering of the quantum Hall ground state under an interlayer bias, provided the two rotated layers are effectively decoupled at low energies. We discuss in detail the electronic structure and the constraints on system parameters, such as the angle, interactions and magnetic flux, required to reach the pseudo-QSH phase. We find, in particular, that purely local electronic interactions are not sufficient to account for the experimental observations, which demand at least nearest-neighbour interactions to be included.
Inhomogeneity in microstructure and mechanical properties during twist extrusion
Energy Technology Data Exchange (ETDEWEB)
Noor, Sh. Vakili [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Eivani, A.R., E-mail: aeivani@iust.ac.ir [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jafarian, H.R. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Mirzaei, M. [Material Engineering Group, Islamic Azad University, Kermanshah (Iran, Islamic Republic of)
2016-01-15
In the present paper, the effect of twist extrusion (TE) on the variations of hardness and tensile properties in commercial pure copper is investigated. It is found that hardness, yield and ultimate tensile strength of the alloy increased by increasing distance from the center of the sample after one pass TE. Similar consequences are observed when the second pass of deformation is considered. This is attributed to inhomogeneity of deformation and the higher strain imposed on the material at the peripheral regions. It should be noted that the inhomogeneity is increased at the second pass when route A of deformation is utilized and reduces by utilization of route D. This has as a well-established effect on the development of microstructure throughout the cross section of the samples. In fact, it is found that the microstructure at the peripheral regions is more significantly deformed leading to higher dislocation density and extensive subgrain formation. In addition, it is found that at the second pass using route A, inhomogeneity of deformation and microstructure increases. However, less inhomogeneity is observed when route D is utilized which is in line with the hardness and tensile test results. In the end, it is concluded that depending on the aim of the SPD process, if more homogeneous deformation and microstructure is required, route D is recommended and route A should be utilized in case if maximum inhomogeneity is desirable.
Propulsion and hydrodynamic particle transport of magnetically twisted colloidal ribbons
Massana-Cid, Helena; Martinez-Pedrero, Fernando; Navarro-Argemí, Eloy; Pagonabarraga, Ignacio; Tierno, Pietro
2017-10-01
We describe a method to trap, transport and release microscopic particles in a viscous fluid using the hydrodynamic flow field generated by a magnetically propelled colloidal ribbon. The ribbon is composed of ferromagnetic microellipsoids that arrange with their long axis parallel to each other, a configuration that is energetically favorable due to their permanent magnetic moments. We use an external precessing magnetic field to torque the anisotropic particles forming the ribbon, and to induce propulsion of the entire structure due to the hydrodynamic coupling with the close substrate. The propulsion speed of the ribbon can be controlled by varying the driving frequency, or the amplitude of the precessing field. The latter parameter is also used to reduce the average inter particle distance and to induce the twisting of the ribbon due to the increase in the attraction between the rotating ellipsoids. Furthermore, non magnetic particles are attracted or repelled with the hydrodynamic flow field generated by the propelling ribbon. The proposed method may be used in channel free microfluidic applications, where the precise trapping and transport of functionalized particles via non invasive magnetic fields is required.
A topologically twisted index for three-dimensional supersymmetric theories
Energy Technology Data Exchange (ETDEWEB)
Benini, Francesco [Delta Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Blackett Laboratory, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Zaffaroni, Alberto [Dipartimento di Fisica, Università di Milano-Bicocca, I-20126 Milano (Italy); INFN, sezione di Milano-Bicocca,I-20126 Milano (Italy)
2015-07-23
We provide a general formula for the partition function of three-dimensional N=2 gauge theories placed on S{sup 2}×S{sup 1} with a topological twist along S{sup 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{sup 2} and four-dimensional theories on S{sup 2}×T{sup 2}. In particular this provides an alternative way to compute genus-zero A-model topological amplitudes and Gromov-Witten invariants.
Germinated grains: a superior whole grain functional food?
Nelson, Kristina; Stojanovska, Lily; Vasiljevic, Todor; Mathai, Michael
2013-06-01
Grains are global dietary staples that when consumed in whole grain form, offer considerable health benefits compared with milled grain foods, including reduced body weight gain and reduced cardiovascular and diabetes risks. Dietary patterns, functional foods, and other lifestyle factors play a fundamental role in the development and management of epidemic lifestyle diseases that share risks of developing adverse metabolic outcomes, including hyperglycaemia, hypertension, dyslipidaemia, oxidative stress, and inflammation. Whole grains provide energy, nutrients, fibres, and bioactive compounds that may synergistically contribute to their protective effects. Despite their benefits, the intake of grains appears to be lower than recommended in many countries. Of emerging interest is the application of germination processes, which may significantly enhance the nutritional and bioactive content of grains, as well as improve palatability. Enhancing grain foods in a natural way using germination techniques may therefore offer a practical, natural, dietary intervention to increase the health benefits and acceptability of whole grains, with potentially widespread effects across populations in attenuating adverse lifestyle disease outcomes. Continuing to build on the growing body of in-vitro studies requires substantiation with extended in-vivo trials so that we may further develop our understanding of the potential of germinated grains as a functional food.
Yang, Jiajia; Hu, Ping; Zhou, Mingli; Huang, Jietao; Liu, Manran
2013-09-01
To construct a retroviral vector carrying Twist gene and investigate its effect on human mammary MCF10A epithelial cells. Myc-Twist was digested from pcDNA3/myc-Twist and subcloned into the retroviral vector pBABE-puro to construct a recombinant plasmid (pBABE-myc-Twist). The inserted Twist gene was confirmed by restriction enzyme digestion and DNA sequencing. The plasmid pBABE-myc-Twist and the packaging plasmid pAmpho were co-transfected into HEK293T cells for packaging of retrovirus. Meanwhile, the control plasmid pBABE-puro and the packaging plasmid were co-transfected into the other HEK293T cells as a control group. Human mammary MCF10A epithelial cells were infected with the retroviruses carrying Twist gene or the controls, and selected by puromycin. The expression of Twist in the MCF10A-Twist and MCF10A-Vector cells was determined by RT-PCR and Western blotting. The expressions of epithelial-mesenchymal transition (EMT) marker proteins induced by Twist in MCF10A cells were detected using immunofluorescence cytochemistry and Western blotting. Cell migration and invasion abilities were analyzed by Transwell(R); assay. The myc-tagged Twist gene was correctly inserted into the retroviral expression vector as a recombinant plasmid (pBABE-myc-Twist) as identified by restriction analysis and DNA sequencing. The Twist gene was efficiently delivered into human mammary MCF10A epithelial cells by the retrovirus, resulting in the stable expression of Twist mRNA and myc-tagged Twist protein as shown by RT-PCR and Western blotting, respectively. The expression of the epithelial biomarker E-cadherin was downregulated whereas, the mesenchymal marker vimentin upregulated in MCF10A-Twist cells as shown by immunofluorescence cytochemistry and Western blotting. Cell migration and invasion abilities were enhanced notably in MCF10A-Twist cells as compared with MCF10A-Vector control cells (PMCF10A cells and plays an important role in the promotion of cell migration and invasion.
Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.
2012-01-01
We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...
Shock processing of interstellar grains
International Nuclear Information System (INIS)
Seab, C.G.; Shull, J.M.
1986-01-01
Shock processing plays an important role in the life of a typical interstellar grain. Shocks of 100 km/s-l or greater can destroy about 50% of the grain material under appropriate preshock conditions of density and magnetic field. The destruction occurs by grain-grain collisions and nonthermal sputtering for steady state radiative shocks and by thermal sputtering for fast adiabatic shocks. The evaluation of the lifetime of grains against shock destruction depends on models of the interstellar medium (ISM) structure and on supernova remnants (SNR) evolution. Results from various authors give lifetimes between 10 to the 8th and 10 to the 9th power years, compared to typical injection times for new grains of a few times 10 to the 9th power years. These numbers require that a major portion of the interstellar silicon bearing grain material must be formed by grain growth in the ISM. At the same time, the presence of isotopic anomalies in some meteorites implies that at least some grains must survive from their formation in SNRs or red giant winds through incorporation into the solar system
Directory of Open Access Journals (Sweden)
Barbara P. Barna
2013-12-01
Full Text Available Sarcoidosis, a chronic granulomatous disease of unknown cause, has been linked to several environmental risk factors, among which are some that may favor carbon nanotube formation. Using gene array data, we initially observed that bronchoalveolar lavage (BAL cells from sarcoidosis patients displayed elevated mRNA of the transcription factor, Twist1, among many M1-associated genes compared to healthy controls. Based on this observation we hypothesized that Twist1 mRNA and protein expression might become elevated in alveolar macrophages from animals bearing granulomas induced by carbon nanotube instillation. To address this hypothesis, wild-type and macrophage-specific peroxisome proliferator-activated receptor gamma (PPARγ knock out mice were given oropharyngeal instillation of multiwall carbon nanotubes (MWCNT. BAL cells obtained 60 days later exhibited significantly elevated Twist1 mRNA expression in granuloma-bearing wild-type or PPARγ knock out alveolar macrophages compared to sham controls. Overall, Twist1 expression levels in PPARγ knock out mice were higher than those of wild-type. Concurrently, BAL cells obtained from sarcoidosis patients and healthy controls validated gene array data: qPCR and protein analysis showed significantly elevated Twist1 in sarcoidosis compared to healthy controls. In vitro studies of alveolar macrophages from healthy controls indicated that Twist1 was inducible by classical (M1 macrophage activation stimuli (LPS, TNFα but not by IL-4, an inducer of alternative (M2 macrophage activation. Findings suggest that Twist1 represents a PPARγ-sensitive alveolar macrophage M1 biomarker which is induced by inflammatory granulomatous disease in the MWCNT model and in human sarcoidosis.
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
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.
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.
Modelling of grain refinement driven by negative grain boundary energy
Czech Academy of Sciences Publication Activity Database
Fischer, F. D.; Zickler, G. A.; Svoboda, Jiří
2017-01-01
Roč. 97, č. 23 (2017), s. 1963-1977 ISSN 1478-6435 R&D Projects: GA ČR(CZ) GA15-06390S Institutional support: RVO:68081723 Keywords : grain refinement * grain nucleation * distribution concept * jump on distribution function Subject RIV: BJ - Thermodynamics OBOR OECD: Thermodynamics Impact factor: 1.505, year: 2016
Substituting maize grain with barley grain in concentrates fed to ...
African Journals Online (AJOL)
The aim of the study was to determine the effect of substituting maize grain with barley grain in the diet of lactating Jersey cows grazing kikuyu-ryegrass pasture. Sixty Jersey cows were blocked in terms of number of days in milk, lactation number, milk yield and live weight and randomly assigned to one of five treatments (n ...
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
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.
Blazar spectral variability as explained by a twisted inhomogeneous jet.
Raiteri, C M; Villata, M; Acosta-Pulido, J A; Agudo, I; Arkharov, A A; Bachev, R; Baida, G V; Benítez, E; Borman, G A; Boschin, W; Bozhilov, V; Butuzova, M S; Calcidese, P; Carnerero, M I; Carosati, D; Casadio, C; Castro-Segura, N; Chen, W-P; Damljanovic, G; D'Ammando, F; Di Paola, A; Echevarría, J; Efimova, N V; Ehgamberdiev, Sh A; Espinosa, C; Fuentes, A; Giunta, A; Gómez, J L; Grishina, T S; Gurwell, M A; Hiriart, D; Jermak, H; Jordan, B; Jorstad, S G; Joshi, M; Kopatskaya, E N; Kuratov, K; Kurtanidze, O M; Kurtanidze, S O; Lähteenmäki, A; Larionov, V M; Larionova, E G; Larionova, L V; Lázaro, C; Lin, C S; Malmrose, M P; Marscher, A P; Matsumoto, K; McBreen, B; Michel, R; Mihov, B; Minev, M; Mirzaqulov, D O; Mokrushina, A A; Molina, S N; Moody, J W; Morozova, D A; Nazarov, S V; Nikolashvili, M G; Ohlert, J M; Okhmat, D N; Ovcharov, E; Pinna, F; Polakis, T A; Protasio, C; Pursimo, T; Redondo-Lorenzo, F J; Rizzi, N; Rodriguez-Coira, G; Sadakane, K; Sadun, A C; Samal, M R; Savchenko, S S; Semkov, E; Skiff, B A; Slavcheva-Mihova, L; Smith, P S; Steele, I A; Strigachev, A; Tammi, J; Thum, C; Tornikoski, M; Troitskaya, Yu V; Troitsky, I S; Vasilyev, A A; Vince, O
2017-12-21
Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence. Changes in the viewing angle of the observed emitting knots or jet regions have also been suggested as an explanation of flaring events and can also explain specific properties of blazar emission, such as intra-day variability, quasi-periodicity and the delay of radio flux variations relative to optical changes. Such a geometric interpretation, however, is not universally accepted because alternative explanations based on changes in physical conditions-such as the size and speed of the emitting zone, the magnetic field, the number of emitting particles and their energy distribution-can explain snapshots of the spectral behaviour of blazars in many cases. Here we report the results of optical-to-radio-wavelength monitoring of the blazar CTA 102 and show that the observed long-term trends of the flux and spectral variability are best explained by an inhomogeneous, curved jet that undergoes changes in orientation over time. We propose that magnetohydrodynamic instabilities or rotation of the twisted jet cause different jet regions to change their orientation and hence their relative Doppler factors. In particular, the extreme optical outburst of 2016-2017 (brightness increase of six magnitudes) occurred when the corresponding emitting region had a small viewing angle
Blazar spectral variability as explained by a twisted inhomogeneous jet
Raiteri, C. M.; Villata, M.; Acosta-Pulido, J. A.; Agudo, I.; Arkharov, A. A.; Bachev, R.; Baida, G. V.; Benítez, E.; Borman, G. A.; Boschin, W.; Bozhilov, V.; Butuzova, M. S.; Calcidese, P.; Carnerero, M. I.; Carosati, D.; Casadio, C.; Castro-Segura, N.; Chen, W.-P.; Damljanovic, G.; D'Ammando, F.; di Paola, A.; Echevarría, J.; Efimova, N. V.; Ehgamberdiev, Sh. A.; Espinosa, C.; Fuentes, A.; Giunta, A.; Gómez, J. L.; Grishina, T. S.; Gurwell, M. A.; Hiriart, D.; Jermak, H.; Jordan, B.; Jorstad, S. G.; Joshi, M.; Kopatskaya, E. N.; Kuratov, K.; Kurtanidze, O. M.; Kurtanidze, S. O.; Lähteenmäki, A.; Larionov, V. M.; Larionova, E. G.; Larionova, L. V.; Lázaro, C.; Lin, C. S.; Malmrose, M. P.; Marscher, A. P.; Matsumoto, K.; McBreen, B.; Michel, R.; Mihov, B.; Minev, M.; Mirzaqulov, D. O.; Mokrushina, A. A.; Molina, S. N.; Moody, J. W.; Morozova, D. A.; Nazarov, S. V.; Nikolashvili, M. G.; Ohlert, J. M.; Okhmat, D. N.; Ovcharov, E.; Pinna, F.; Polakis, T. A.; Protasio, C.; Pursimo, T.; Redondo-Lorenzo, F. J.; Rizzi, N.; Rodriguez-Coira, G.; Sadakane, K.; Sadun, A. C.; Samal, M. R.; Savchenko, S. S.; Semkov, E.; Skiff, B. A.; Slavcheva-Mihova, L.; Smith, P. S.; Steele, I. A.; Strigachev, A.; Tammi, J.; Thum, C.; Tornikoski, M.; Troitskaya, Yu. V.; Troitsky, I. S.; Vasilyev, A. A.; Vince, O.
2017-12-01
Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence. Changes in the viewing angle of the observed emitting knots or jet regions have also been suggested as an explanation of flaring events and can also explain specific properties of blazar emission, such as intra-day variability, quasi-periodicity and the delay of radio flux variations relative to optical changes. Such a geometric interpretation, however, is not universally accepted because alternative explanations based on changes in physical conditions—such as the size and speed of the emitting zone, the magnetic field, the number of emitting particles and their energy distribution—can explain snapshots of the spectral behaviour of blazars in many cases. Here we report the results of optical-to-radio-wavelength monitoring of the blazar CTA 102 and show that the observed long-term trends of the flux and spectral variability are best explained by an inhomogeneous, curved jet that undergoes changes in orientation over time. We propose that magnetohydrodynamic instabilities or rotation of the twisted jet cause different jet regions to change their orientation and hence their relative Doppler factors. In particular, the extreme optical outburst of 2016–2017 (brightness increase of six magnitudes) occurred when the corresponding emitting region had a small viewing
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.
Effect of -bar 2 grain boundaries on plastic deformation of WC-Co cemented carbides
Energy Technology Data Exchange (ETDEWEB)
Ostberg, G. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)]. E-mail: gusto@fy.chalmers.se; Farooq, M.U. [Department of Materials and Manufacturing Technology, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Christensen, M. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Andren, H.-O. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Klement, U. [Department of Materials and Manufacturing Technology, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Wahnstroem, G. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)
2006-01-25
Cutting inserts of WC-6wt.% Co were investigated before and after plastic deformation. The deformation tests were performed with a turning operation under realistic, yet controlled, conditions. SEM studies showed that after deformation the WC skeleton structure had broken up and thin lamellae of binder phase had formed in less than 10% of the grain boundaries. Ab initio calculations showed that -bar 2 twist WC/WC boundaries have a high work of separation and the interface energy is not lowered by forming two Co/WC boundaries. Electron backscattered diffraction (EBSD) measurements showed an apparent increase in the relative occurrence of -bar 2 boundaries due to poor indexing of the deformed material. The accumulation of dislocations in general boundaries is held responsible for the difficulty in identifying them compared with -bar 2 boundaries. At the -bar 2 tilt boundary the grains have the glide planes {l_brace}101-bar 0{r_brace} in common and at the -bar 2 twist boundary there are three glide planes intersecting, which facilitate dislocation movements across the -bar 2 boundaries.
Ab Initio Study of Electronic Transport in Cubic-HfO2 Grain Boundaries
Directory of Open Access Journals (Sweden)
Elena Degoli
2017-01-01
Full Text Available In polycrystalline materials the grain boundaries (GBs are particularly important as they can act as a sink for atom defects and impurities, which may drive structural transformation of the materials and consequently modify their properties. Characterising the structure and properties of GBs is critical for understanding and controlling material property. Here, we investigated how GBs can modify the structural, electronic, and transport properties of the polycrystalline material HfO2. In general, grain boundaries are considered to be detrimental to the physical stability and electronic transport in HfO2. Anyway, studying by first principles the two most stable and common types of GBs, the tilt and the twist, we found substantial differences on the impact they have on the material properties. In fact, while tilt defects create channels of different sizes and shapes in hafnia along which the electronic transport is stronger in relation to leakage current through GBs, twist defects create a sort of amorphous structure that tends to resemble the bulk and which is independent of the number of rotated planes/atoms.
Energy Technology Data Exchange (ETDEWEB)
Rudman, K. [Arizona State Univ., Tempe, AZ (United States); Dickerson, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Byler, Darrin David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Peralta, P. [Arizona State Univ., Tempe, AZ (United States); Lim, H. [Arizona State Univ., Tempe, AZ (United States); McDonald, R. [Arizona State Univ., Tempe, AZ (United States); Dickerson, R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mcclellan, Kenneth James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-09-06
The initial microstructure of an oxide fuel can play a key role in its performance. At low burn-ups, the diffusion of fission products can depend strongly on grain size and grain boundary (GB) characteristics, which in turn depend on processing conditions and oxygen stoichiometry. Serial sectioning techniques using Focused Ion Beam were developed to obtain Electron Backscatter Diffraction (EBSD) data for depleted UO2 pellets that were processed to obtain 3 different oxygen stoichiometries. The EBSD data were used to create 3D microstructure reconstructions and to gather statistical information on the grain and GB crystallography, with emphasis on identifying the character (twist, tilt, mixed) for GBs that meet the Coincident Site Lattice (CSL) criterion as well as GBs with the most common misorientation angles. Data on dihedral angles at triple points were also collected. The results were compared across different samples to understand effects of oxygen content on microstructure evolution.
Energy Technology Data Exchange (ETDEWEB)
Andersson, Anders D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tonks, Michael R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Casillas, Luis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nerikar, Pankaj [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vyas, Shyam [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Uberuaga, Blas P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Christopher R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-10-31
In light water reactor fuel, gaseous fission products segregate to grain boundaries, resulting in the nucleation and growth of large intergranular fission gas bubbles. Based on the mechanisms established from density functional theory (DFT) and empirical potential calculations 1, continuum models for diffusion of xenon (Xe), uranium (U) vacancies and U interstitials in UO_{2} have been derived for both intrinsic conditions and under irradiation. Segregation of Xe to grain boundaries is described by combining the bulk diffusion model with a model for the interaction between Xe atoms and three different grain boundaries in UO_{2} ( Σ5 tilt, Σ5 twist and a high angle random boundary),as derived from atomistic calculations. All models are implemented in the MARMOT phase field code, which is used to calculate effective Xe and U diffusivities as well as redistribution for a few simple microstructures.
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, [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.
Bildsoe, Heidi; Loebel, David A F; Jones, Vanessa J; Hor, Angelyn C C; Braithwaite, Antony W; Chen, You-Tzung; Behringer, Richard R; Tam, Patrick P L
2013-02-15
The basic helix-loop-helix transcription factor Twist1 is a key regulator of craniofacial development. Twist1-null mouse embryos exhibit failure of cephalic neural tube closure and abnormal head development and die at E11.0. To dissect the function of Twist1 in the cranial mesoderm beyond mid-gestation, we used Mesp1-Cre to delete Twist1 in the anterior mesoderm, which includes the progenitors of the cranial mesoderm. Deletion of Twist1 in mesoderm cells resulted in loss and malformations of the cranial mesoderm-derived skeleton. Loss of Twist1 in the mesoderm also resulted in a failure to fully segregate the mesoderm and the neural crest cells, and the malformation of some cranial neural crest-derived tissues. The development of extraocular muscles was compromised whereas the differentiation of branchial arch muscles was not affected, indicating a differential requirement for Twist1 in these two types of craniofacial muscle. A striking effect of the loss of Twist1 was the inability of the mesodermal cells to maintain their mesenchymal characteristics, and the acquisition of an epithelial-like morphology. Our findings point to a role of Twist1 in maintaining the mesenchyme architecture and the progenitor state of the mesoderm, as well as mediating mesoderm-neural crest interactions in craniofacial development. Copyright © 2012 Elsevier Inc. All rights reserved.
The spectral problem for strings on twisted AdS{sub 5} Multiplication-Sign S{sup 5}
Energy Technology Data Exchange (ETDEWEB)
Leeuw, Marius de, E-mail: deleeuwm@phys.ethz.ch [ETH Zuerich, Institut fuer Theoretische Physik, Wolfgang-Pauli-Str. 27, CH-8093 Zurich (Switzerland); van Tongeren, Stijn J., E-mail: s.j.vantongeren@uu.nl [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands)
2012-07-21
We discuss the spectral problem for integrable superstrings on generically twisted AdS{sub 5} Multiplication-Sign S{sup 5}, meaning all its orbifolds and TsT transformed versions. We explicitly give the asymptotic description of these theories through a twisted transfer matrix, and carefully match the geometric deformations with twists allowed by integrability. We then discuss the mirror TBA equations that describe these theories at finite size. This unifies the treatment of various specific deformations previously considered in this setting, and extends it to completely general twists.
Critical heat flux characteristics of R-113 boiling two-phase flow in twisted-tape-inserted tubes
International Nuclear Information System (INIS)
Lee, Sangr-Youl; Inoue, Akira; Takahashi, Minoru
1995-01-01
This paper presents experimental data on the critical heat flux (CHF) in twisted-tape-inserted tubes over a wide quality range of -0.25 to 0.8. The influences of quality, twist ratio, mass velocity, and clearance between the twisted tape and tube inner wall on CHF were investigated. In the subcooled region, it was observed, using an infrared thermoviewer, that CHF was initiated locally at the wall near the twisted tape. Consequently, twisted tape insertion with small tape-wall clearance decreased CHF to below the value in the empty tubes at a low flow rate. This decrease was found to be avoidable by adjusting the clearance. In the net quality region, CHF in the twisted-tape-inserted tubes increased with increasing flow rate contrary to the case of the empty tubes. However, CHF in the net quality region was also decreased by insertion of twisted tapes with high twist ratio (loosely twisted tapes) at a very low flow rate. (author)
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
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.
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.
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 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)
Ramnarayan, R; Arulmurugan, B; Wilson, Paul M; Nayar, Rani
2008-09-01
Chronic subdural haematoma is a disease of the elderly and surgery in these patients carries a much higher risk. The common surgical procedures for chronic subdural haematoma include twist drill craniostomy, burr hole evacuation or craniotomy. The aim of this study was to analyse the results of twist drill craniostomy with drainage in elderly patients with chronic subdural haematoma. Forty-two elderly patients (>65 years) with radiologically proven chronic subdural haematoma were analysed. All the patients underwent twist drill craniostomy and continuous drainage of the haematoma under local anaesthesia and total intravenous anaesthesia (TIVA). There were 24 males and 18 females. Headache and cognitive decline was seen in 50% and weakness of limbs in 60% of patients. CT scan was done in all cases. All patients underwent twist drill 2-3 cm in front of the parietal eminence under local anaesthesia. The drain was left for 24-72 h depending on the drainage. At 1 week, 88% of patients had a good outcome. Twist drill craniostomy with drainage under local anaesthesia is a safe and effective procedure for chronic subdural haematoma in the elderly and could be used as the first and only option in these people.
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
Alignment of suprathermally rotating grains
Lazarian, A.
1995-12-01
It is shown that mechanical alignment can be efficient for suprathermally rotating grains, provided that they drift with supersonic velocities. Such a drift should be widely spread due to both Alfvenic waves and ambipolar diffusion. Moreover, if suprathermal rotation is caused by grain interaction with a radiative flux, it is shown that mechanical alignment may be present even in the absence of supersonic drift. This means that the range of applicability of mechanical alignment is wider than generally accepted and that it can rival the paramagnetic one. We also study the latter mechanism and re-examine the interplay between poisoning of active sites and desorption of molecules blocking the access to the active sites of H_2 formation, in order to explain the observed poor alignment of small grains and good alignment of large grains. To obtain a more comprehensive picture of alignment, we briefly discuss the alignment by radiation fluxes and by grain magnetic moments.
Autonomous grain combine control system
Hoskinson, Reed L.; Kenney, Kevin L.; Lucas, James R.; Prickel, Marvin A.
2013-06-25
A system for controlling a grain combine having a rotor/cylinder, a sieve, a fan, a concave, a feeder, a header, an engine, and a control system. The feeder of the grain combine is engaged and the header is lowered. A separator loss target, engine load target, and a sieve loss target are selected. Grain is harvested with the lowered header passing the grain through the engaged feeder. Separator loss, sieve loss, engine load and ground speed of the grain combine are continuously monitored during the harvesting. If the monitored separator loss exceeds the selected separator loss target, the speed of the rotor/cylinder, the concave setting, the engine load target, or a combination thereof is adjusted. If the monitored sieve loss exceeds the selected sieve loss target, the speed of the fan, the size of the sieve openings, or the engine load target is adjusted.
Methods of assessing grain-size distribution during grain growth
DEFF Research Database (Denmark)
Tweed, Cherry J.; Hansen, Niels; Ralph, Brian
1985-01-01
This paper considers methods of obtaining grain-size distributions and ways of describing them. In order to collect statistically useful amounts of data, an automatic image analyzer is used, and the resulting data are subjected to a series of tests that evaluate the differences between two related...... distributions (before and after grain growth). The distributions are measured from two-dimensional sections, and both the data and the corresponding true three-dimensional grain-size distributions (obtained by stereological analysis) are collected. The techniques described here are illustrated by reference...
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
Energy Technology Data Exchange (ETDEWEB)
Vadim Guzey, Mark Strikman
2010-04-01
The leading twist theory of nuclear shadowing predicts nuclear parton distributions in the small $x$ shadowing region by connecting them to the leading twist hard diffraction in electron-nucleon scattering. The uncertainties of the predictions are related to the shadowing effects resulting from the interaction of the hard probe with $N \\ge 3$ nucleons. We argue that the pattern of hard diffraction observed at HERA allows one to reduce these uncertainties, and we develop a new approach to the treatment of these multiple collisions. It is based on the concept of the color fluctuations and accounts for the presence of both point-like and hadron-like configurations in the virtual photon. Using the developed framework, we update our predictions for the effect of the leading twist nuclear shadowing in nuclear parton distributions of heavy nuclei at small $x$.
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.
International Nuclear Information System (INIS)
Clark, Emily; Ramirez, Emilio; Ruggles, Art E.; Griffard, Cory
2015-01-01
The modeling capability for tubes with twisted tape inserts is reviewed with reference to the application of cooling plasma facing components in magnetic confinement fusion devices. The history of experiments examining the cooling performance of tubes with twisted tape inserts is reviewed with emphasis on the manner of heating, flow stability limits and the details of the test section and fluid delivery system. Models for heat transfer, burnout, and onset of net vapor generation in straight tube flows and tube with twisted tape are compared. As a result, the gaps in knowledge required to establish performance limits of the plasma facing components are identified and attributes of an experiment to close those gaps are presented
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.
Dual-Band Notch Filter Based on Twist Split Ring Resonators
Directory of Open Access Journals (Sweden)
Haibin Sun
2014-01-01
Full Text Available A novel dual-band rectangular waveguide notch filter is experimentally investigated in this paper. Such filter is realized by integrating two pairs of split ring resonators (SRRs printed on the two sides of a dielectric slab with twist angles and separated as a distance in the center of the rectangular waveguide. Due to the coupling effects between the twist SRRs and between the original SRRs and their mirror images generated by the metallic walls perpendicular to the E-field direction, it can flexibly contribute two disjunct resonance states and result in the dual-band notch properties. Furthermore, the two resonance frequencies can be controlled by changing the twist angles, resulting in the shifts of notch frequency bands.
Development of an Active Twist Rotor for Wind: Tunnel Testing (NLPN97-310
Cesnik, Carlos E. S.; Shin, SangJoon; Hagood, Nesbitt W., IV
1998-01-01
The development of the Active Twist Rotor prototype blade for hub vibration and noise reduction studies is presented in this report. Details of the modeling, design, and manufacturing are explored. The rotor blade is integrally twisted by direct strain actuation. This is accomplished by distributing embedded piezoelectric fiber composites along the span of the blade. The development of the analysis framework for this type of active blade is presented. The requirements for the prototype blade, along with the final design results are also presented. A detail discussion on the manufacturing aspects of the prototype blade is described. Experimental structural characteristics of the prototype blade compare well with design goals, and preliminary bench actuation tests show lower performance than originally predicted. Electrical difficulties with the actuators are also discussed. The presented prototype blade is leading to a complete fully articulated four-blade active twist rotor system for future wind tunnel tests.
Coupling Current and Hysteresis Losses of Bi2212 Round Wires with Twisted Filaments
Yang, I; Young, EA; Falorio, I; Ballarino, A; Bottura, L; Miao, H; Huang, Y
2015-01-01
AC loss measurements have been carried out on Bi2212 round wires of different twist pitches. With systematical variation of sample temperature (5 K – 70 K) and ac field amplitude (≤0.2 T) as well as frequency (20 Hz – 2 kHz), this work shows (a) the full coupling of the non-twisted wire, (b) the uncoupling of sub-wires by twisting at moderate pitch up to 12 mm, (c) a relatively short time constant of milliseconds for the coupling current due to a high transverse resistivity, and (d) an effective (de)coupling diameter of 0.4mm about 1.6x of sub-wire bundles. The results suggest a promising potential for improving filament decoupling.
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
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...... 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...... 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....
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.)
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...
Prevalence of IgE antibodies to grain and grain dust in grain elevator workers
International Nuclear Information System (INIS)
Lewis, D.M.; Romeo, P.A.; Olenchock, S.A.
1986-01-01
IgE-mediated allergic reactions have been postulated to contribute to respiratory reactions seen in workers exposed to grain dusts. In an attempt better to define the prevalence of IgE antibodies in workers exposed to grain dusts, we performed the radioallergosorbent test (RAST) on worker sera using both commercial allergens prepared from grain and worksite allergens prepared from grain dust samples collected at the worksite. We found that the two types of reagents identified different populations with respect to the specificity of IgE antibodies present. The RAST assay performed using worksite allergens correlated well with skin test procedures. These results may allow us to gain better understanding of allergy associated with grain dust exposure, and document the utility of the RAST assay in assessment of occupational allergies
MATHEMATICAL MODEL OF GRAIN MICRONIZATION
Directory of Open Access Journals (Sweden)
V. A. Afanas’ev
2014-01-01
Full Text Available Summary. During micronisation grain moisture evaporates mainly in decreasing drying rate period. Grain layer located on the surface of the conveyor micronisers will be regarded as horizontal plate. Due to the fact that the micronisation process the surface of the grain evaporates little moisture (within 2-7 % is assumed constant plate thickness. Because in the process of micronization grain structure is changing, in order to achieve an exact solution of the equations necessary to take into account changes thermophysical, optical and others. Equation of heat transfer is necessary to add a term that is responsible for the infrared heating. Because of the small thickness of the grain, neglecting the processes occurring at the edge of the grain, that is actually consider the problem of an infinite plate. To check the adequacy of the mathematical model of the process of micronisation of wheat grain moisture content must be comparable to the function of time, obtained by solving the system of equations with the measured experimental data of experience. Numerical solution of a system of equations for the period of decreasing drying rate is feasible with the help of the Maple 14, substituting the values of the constants in the system. Calculation of the average relative error does not exceed 7- 10 %, and shows a good agreement between the calculated data and the experimental values.
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
Why Is It Important to Eat Grains, Especially Whole Grains?
... nutrients, including dietary fiber , several B vitamins (thiamin, riboflavin, niacin, and folate), and minerals ( iron , magnesium , and selenium). Dietary fiber from whole grains or other foods, may help reduce blood cholesterol levels and may ...
A Simple Method to Measure the Twist Elastic Constant of a Nematic Liquid Crystal
2015-01-01
as 180° super- twisted nematic (STN) cell. Next, we assume the helical twisting power ( HTP ) of chiral dopant is also unknown, same as K22. To solve...threshold voltages of these two 180° STN cells, both K22 and HTP can be obtained simultaneously. In the whole process, there is no need to measure...Equation (1), if we sub- stitute ϕ = π and pitch length P = 1/( HTP · c) (where c is chiral concentration), then the critical voltage can be rewritten
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.)
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.
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.
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.
Polarization-dependent diffraction in all-dielectric, twisted-band structures
Energy Technology Data Exchange (ETDEWEB)
Kardaś, Tomasz M.; Jagodnicka, Anna; Wasylczyk, Piotr, E-mail: pwasylcz@fuw.edu.pl [Photonic Nanostructure Facility, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland)
2015-11-23
We propose a concept for light polarization management: polarization-dependent diffraction in all-dielectric microstructures. Numerical simulations of light propagation show that with an appropriately configured array of twisted bands, such structures may exhibit zero birefringence and at the same time diffract two circular polarizations with different efficiencies. Non-birefringent structures as thin as 3 μm have a significant difference in diffraction efficiency for left- and right-hand circular polarizations. We identify the structural parameters of such twisted-band matrices for optimum performance as circular polarizers.
A first look at maximally twisted mass lattice QCD calculations at the physical point
International Nuclear Information System (INIS)
Abdel-Rehim, A.
2013-11-01
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 f =2 results and their phenomenological values. Finally, the strategy for extending simulations to N f =2+1+1 is outlined.
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.
Pseudoscalar decay constants from Nf=2+1+1 twisted mass lattice QCD
International Nuclear Information System (INIS)
Farchioni, Federico; Petschlies, Marcus; Urbach, Carsten
2010-12-01
We present first results for the pseudoscalar decay constants f K , f D and f D S from lattice QCD with N 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.)
Naked eye picometer resolution in a Michelson interferometer using conjugated twisted beams.
Emile, Olivier; Emile, Janine
2017-01-15
Michelson interferometry is one of the most widely used techniques for accuracy measurements. Its main characteristic feature is to infer a displacement in one of the arms of the interferometer from a phase measurement. Two different twisted beams, also called vortex beams, with opposite twisted rotations in each arm of the interferometer interfere in a daisy flower-like pattern. The number of petals is twice the topological charge. Their position depends on the relative phase of the beams. Naked eye detection of 44 pm displacements is achieved. The sensitivity of such an interferometer together with possible further improvements, and applications are then discussed.
Neufeldt, Sharon R; Jiménez-Osés, Gonzalo; Comins, Daniel L; Houk, K N
2014-12-05
The role of twist-boat conformers of cyclohexanones in hydride reductions was explored. The hydride reductions of a cis-2,6-disubstituted N-acylpiperidone, an N-acyltropinone, and tert-butylcyclohexanone by lithium aluminum hydride and by a bulky borohydride reagent were investigated computationally and compared to experiment. Our results indicate that in certain cases, factors such as substrate conformation, nucleophile bulkiness, and remote steric features can affect stereoselectivity in ways that are difficult to predict by the general Felkin-Anh model. In particular, we have calculated that a twist-boat conformation is relevant to the reactivity and facial selectivity of hydride reduction of cis-2,6-disubstituted N-acylpiperidones with a small hydride reagent (LiAlH4) but not with a bulky hydride (lithium triisopropylborohydride).
Hata, K.; Fukuda, K.; Masuzaki, S.
2018-04-01
Twisted-tape-induced swirl-flow heat transfer due to exponentially increasing heat inputs with various exponential periods ( Q = Q 0 exp(t/τ), τ = 6.04 to 23.07 s) and twisted-tape-induced pressure drop was systematically measured for various mass velocities ( G = 4115 to 13,656 kg/m2 s), inlet liquid temperatures ( T in = 285.88 to 299.09 K), and inlet pressures ( P in = 847.45 to 943.29 kPa) using an experimental water loop flow. Measurements were made over a 59.2-mm effective length and three sections (upper, middle, and lower positions), within which four potential taps were spot-welded onto the outer surface of a 6-mm-inner-diameter, 69.6-mm-heated length, 0.4-mm-thickness platinum circular test tube. Type SUS304 twisted tapes with a width w = 5.6 mm, a thickness δ T = 0.6 mm, a total length l = 372 mm, and twist ratios y = 2.39 and 4.45 were employed in this study. The RANS equations (Reynolds Averaged Navier-Stokes Simulation) with a k-ɛ turbulence model for a circular tube 6 mm in diameter and 636 mm in length were numerically solved for heating of water with a heated section 6 mm in diameter and 70 mm in length using the CFD code, under the same conditions as the experimental ones and considering the temperature dependence of the thermo-physical properties concerned. The theoretical values of surface heat flux q on the circular tubes with twisted tapes with twist ratios y of 2.39 and 4.45 were found to be almost in agreement with the corresponding experimental values of heat flux q, with deviations of less than 30% for the range of temperature difference between the average heater inner surface temperature and the liquid bulk mean temperature ΔT L [ = T s,av - T L , T L = ( T in + T out )/2] considered in this study. The theoretical values of the local surface temperature T s , local average liquid temperature T f,av , and local liquid pressure drop ΔP x were found to be within almost 15% of the corresponding experimental ones. The thickness of the
Virginia Grain Sorghum Performance Tests, 2016
Balota, Maria; Oakes, Joseph; Mehl, H. L.; Acharya, Bhupendra
2017-01-01
Offers data about the grain sorghum testing program, and evaluations of commercial and experimental varieties of grain sorghum. Statistical analyses are provided, as well as information on relative yield, grain moisture, head mold, and more.
Virginia Grain Sorghum Performance Tests, 2015
Balota, Maria; Oakes, Joseph; Thomason, Wade Everett; Pitman, Robert Melvin, 1948-; Mehl, H. L.
2016-01-01
Offers data about the grain sorghum testing program, and evaluations of commercial and experimental varieties of grain sorghum. Statistical analyses are provided, as well as information on relative yield, grain moisture, head mold, and more.
Rule-based expert system to establish the linkage between yarn twist factor and end-use.
CSIR Research Space (South Africa)
Dlodlo, N
2009-09-01
Full Text Available This paper describes the concepts and development of a rule-based expert system to establish the optimum linkage between the yarn twist factor and end-use of a yarn and determine the appropriate twist for the particular yarn. The quality of a yarn...
Directory of Open Access Journals (Sweden)
Qin Tian
2017-04-01
Full Text Available Objective: To study the correlation of Twist and YB-1 gene expression in cervical cancer and precancerous tissue with cell invasion. Methods: Cervical cancer tissue, precancerous tissue and normal cervical tissue surgically removed in our hospital between May 2013 and April 2015 were collected; immunohistochemical staining kits were used to detect the positive protein expression rate of Twist and YB-1 gene; fluorescence quantitative PCR kits were used to detect Twist, YB-1 and invasion gene mRNA expression. Results: Twist and YB-1 mRNA expression and positive protein expression rate as well as USP22, Rab11, Rac1 and ANXA5 mRNA expression in cervical cancer tissue and precancerous tissue were significantly higher than those in normal cervical tissue, Twist and YB-1 mRNA expression and positive protein expression rate as well as USP22, Rab11, Rac1 and ANXA5 mRNA expression in cervical cancer tissue were significantly higher than those in precancerous tissue; USP22, Rab11, Rac1 and ANXA5 mRNA expression in cervical cancer tissue and precancerous tissue with positive Twist and YB-1 expression were significantly higher than those in cervical cancer tissue and precancerous tissue with negative Twist and YB-1 expression. Conclusion: Highly expressed Twist and YB-1 in cervical cancer and precancerous tissue can promote cell invasion.
Bildsoe, Heidi; Fan, Xiaochen; Wilkie, Emilie E.; Ashoti, Ator; Jones, Vanessa J.; Power, Melinda; Qin, Jing; Wang, Junwen; Tam, Patrick P L; Loebel, David A F
2016-01-01
TWIST1, a basic helix-loop-helix transcription factor is essential for the development of cranial mesoderm and cranial neural crest-derived craniofacial structures. We have previously shown that, in the absence of TWIST1, cells within the cranial mesoderm adopt an abnormal epithelial configuration
Neufeldt, Sharon R.; Jim?nez-Os?s, Gonzalo; Comins, Daniel L.; Houk, K. N.
2014-01-01
The role of twist-boat conformers of cyclohexanones in hydride reductions was explored. The hydride reductions of a cis-2,6-disubstituted N-acylpiperidone, an N-acyltropinone, and tert-butylcyclohexanone by lithium aluminum hydride and by a bulky borohydride reagent were investigated computationally and compared to experiment. Our results indicate that in certain cases, factors such as substrate conformation, nucleophile bulkiness, and remote steric features can affect stereoselectivity in wa...
Xe precipitates at grain boundaries in Al under 1 MeV electron irradiation.
Energy Technology Data Exchange (ETDEWEB)
Allen, C. W.
1998-10-23
Crystalline nanoprecipitates of Xe have been produced by ion implantation into mazed bicrystalline Al at 300 K, in which the matrix grain boundaries are mainly 90 deg tilt boundaries. Within Al grains, Xe nanocrystals are fee, isotactic with the Al and cuboctohedral in shape with {l_brace}111{r_brace} and {l_brace}100{r_brace} facets. With an off-axial imaging technique, the nanocrystals were structure imaged against a relatively featureless matrix background. In contrast to metal precipitates in Al, such as Pb, Xe precipitates straddling a matrix grain boundary are bicrystals as small as approximately 2 nm in diameter. Larger Xe precipitates tend to avoid boundaries which are inclined away from asymmetrical orientation and which thus have a significant twist component. Under the 1 MeV electron irradiation employed for HREM observation, small Xe nanocrystals near a grain boundary may migrate to the boundary and coalesce with other Xe precipitates. The structural observations are rationalized on a simple geometrical interpretation.
Hirao, Yasukazu; Nagamachi, Nobuhiro; Hosoi, Katsuma; Kubo, Takashi
2018-03-02
The twisted form of bianthrone is known as a metastable state provided by a photo-induced or thermal-induced isomerization of the folded form, and thus prevents the isolation and the detailed analysis of its electronic structure. In this study, an unsymmetrical bianthrone (2), consisting of the electron-withdrawing anthrone and electron-donating acridane, have been synthesized and shown to exhibit a solvent-polarity-dependent isomerization reaction between the folded and twisted isomers. With increasing the polarity of the solvent, 2 showed an isomerization reaction from the folded form to the twisted form. The stabilization of the twisted isomer in polar solvents can be interpreted as proof of its relatively large zwitterionic character. The DMF solution of 2 displayed paramagnetically-broadened NMR signals from the thermally populated triplet state resulting from rotation of the weakened ethylenic double bond of the twisted isomer. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.
2013-03-01
We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.
Design, Manufacture and Testing of A Bend-Twist D-Spar
Energy Technology Data Exchange (ETDEWEB)
Ong, Cheng-Huat; Tsai, Stephen W.
1999-06-01
Studies have indicated that an adaptive wind turbine blade design can significantly enhance the performance of the wind turbine blade on energy capture and load mitigation. In order to realize the potential benefits of aeroelastic tailoring, a bend-twist D-spar, which is the backbone of a blade, was designed and fabricated to achieve the objectives of having maximum bend-twist coupling and fulfilling desirable structural properties (031 & GJ). Two bend-twist D-spars, a hybrid of glass and carbon fibers and an all-carbon D-spar, were fabricated using a bladder process. One of the D-spars, the hybrid D-spar, was subjected to a cantilever static test and modal testing. Various parameters such as materials, laminate schedule, thickness and internal rib were examined in designing a bend-twist D-spar. The fabrication tooling, the lay-up process and the joint design for two symmetric clamshells are described in this report. Finally, comparisons between the experimental test results and numerical results are presented. The comparisons indicate that the numerical analysis (static and modal analysis) agrees well with test results.
Realizations of κ-Minkowski space, Drinfeld twists, and related symmetry algebras
International Nuclear Information System (INIS)
Juric, Tajron; Meljanac, Stjepan; Pikutic, Danijel
2015-01-01
Realizations of κ-Minkowski space linear in momenta are studied for time-, space- and light-like deformations. We construct and classify all such linear realizations and express them in terms of the gl(n) generators. There are three one-parameter families of linear realizations for timelike and space-like deformations, while for light-like deformations, there are only four linear realizations. The relation between a deformed Heisenberg algebra, the star product, the coproduct of momenta, and the twist operator is presented. It is proved that for each linear realization there exists a Drinfeld twist satisfying normalization and cocycle conditions. κ-Deformed igl(n)-Hopf algebras are presented for all cases. The κ-Poincare-Weyl and κ-Poincare-Hopf algebras are discussed. The left-right dual κ-Minkowski algebra is constructed from the transposed twists. The corresponding realizations are nonlinear. All Drinfeld twists related to κ-Minkowski space are obtained from our construction. Finally, some physical applications are discussed. (orig.)
Two-electron Oxidation of a Twisted Non Anti-aromatic 40π ...
Indian Academy of Sciences (India)
Abstract. Expanded isophlorins are typical examples for stable anti-aromatic systems. Paratropic ring cur- rent effects are observed in their NMR spectra mainly due to their planar conformation. Herein we report the synthesis of the first twisted 40π expanded isophlorin and also its two-electron oxidation to a 38π dication.
A zero torsional stiffness twist morphing blade as a wind turbine load alleviation device
International Nuclear Information System (INIS)
Lachenal, X; Daynes, S; Weaver, P M
2013-01-01
This paper presents the design, analysis and realization of a zero stiffness twist morphing wind turbine blade. The morphing blade is designed to actively twist as a means of alleviating the gust loads which reduce the fatigue life of wind turbine blades. The morphing structure exploits an elastic strain energy balance within the blade to enable large twisting deformations with modest actuation requirements. While twist is introduced using the warping of the blade skin, internal pre-stressed members ensure that a constant strain energy balance is achieved throughout the deformation, resulting in a zero torsional stiffness structure. The torsional stability of the morphing blade is characterized by analysing the elastic strain energy in the device. Analytical models of the skin, the pre-stressed components and the complete blade are compared to their respective finite element models as well as experimental results. The load alleviation potential of the adaptive structure is quantified using a two-dimensional steady flow aerodynamic model which is experimentally validated with wind tunnel measurements. (paper)
Twisted Gastrulation as a BMP Modulator during Mammary Gland Development and Tumorigenesis
2014-05-01
mandibular arch in mice. Dev Biol 328:13-23 6. Melnick M, Petryk A, Abichaker G, Witcher D, Person AD, Jaskoll T 2006 Embryonic salivary gland...21417804] Melnick M, Petryk A, Abichaker G, Witcher D, Person AD, Jaskoll T. Embryonic salivary gland dysmorphogenesis in Twisted gastrulation
Noncommutative Riemannian geometry from quantum spacetime generated by twisted Poincaré group
Aguillón, Cesar A.; Much, Albert; Rosenbaum, Marcos; Vergara, J. David
2017-11-01
We investigate a quantum geometric space in the context of what could be considered an emerging effective theory from quantum gravity. Specifically we consider a two-parameter class of twisted Poincaré algebras, from which Lie-algebraic noncommutativities of the translations are derived as well as associative star-products, deformed Riemannian geometries, Lie-algebraic twisted Minkowski spaces, and quantum effects that arise as noncommutativities. Starting from a universal differential algebra of forms based on the above-mentioned Lie-algebraic noncommutativities of the translations, we construct the noncommutative differential forms and inner and outer derivations, which are the noncommutative equivalents of the vector fields in the case of commutative differential geometry. Having established the essentials of this formalism, we construct a bimodule, which is required to be central under the action of the inner derivations in order to have well-defined contractions and from where the algebraic dependence of its coefficients is derived. This again then defines the noncommutative equivalent of the geometrical line-element in commutative differential geometry. We stress, however, that even though the components of the twisted metric are by construction symmetric in their algebra valuation, it is not so for their inverse, and thus to construct it, we made use of Gel'fand's theory of quasi-determinants, which is conceptually straightforward but computationally quite complicated beyond an algebra of 3 generators. The consequences of the noncommutativity of the Lie-algebra twisted geometry are further discussed.
Effects of twisting of the graft in anterior cruciate ligament reconstruction
Elmans, L.; Wymenga, A.; van Kampen, A.; van der Wielen, P.; Mommersteeg, T. J. A.; Blankevoort, L.
2003-01-01
In an in vitro study on six knees from cadavers, the effect of bone-patellar tendon-bone graft twist on anterior knee laxity was measured at different knee flexion angles. A motion and loading rig was used to prescribe the flexion angle, to restrain axial rotation, and to apply 100 N anterior force
On counting twists of a character appearing in its associated Weil ...
Indian Academy of Sciences (India)
On counting twists of a character appearing in its associated. Weil representation. K VISHNU NAMBOOTHIRI. Department of Mathematics and Statistics, University of Hyderabad,. Hyderabad 500 046, India. Department of Collegiate Education, Government of Kerala, Kerala, India. E-mail: kvnamboothiri@gmail.com.
The asymptotic behaviour of the heat equation in a twisted Dirichlet-Neumann waveguide
Czech Academy of Sciences Publication Activity Database
Krejčiřík, David; Zuazua, E.
2011-01-01
Roč. 250, č. 5 (2011), s. 2334-2346 ISSN 0022-0396 R&D Projects: GA MŠk LC06002 Institutional research plan: CEZ:AV0Z10480505 Keywords : Laplacian * Dirichlet and Neumann boundary conditions * Twist Subject RIV: BE - Theoretical Physics Impact factor: 1.277, year: 2011
Growth behaviour of twisted ribbons of barium carbonate/silica self-assembled ceramics
International Nuclear Information System (INIS)
Garcia-Ruiz, J.M.; Moreno, A.
1997-01-01
Twisted ribbons of self-assembled crystal aggregates of barium carbonate, in the presence of silicate ions at pH 9.5 grow at constant rate between 20 and 50 mu m/min. The morphological behaviour depends on temperature, while it was demonstrated to be independent of the viscosity of the growth environment. (Author) 7 refs
Bubble generation in a twisted and bent DNA-like model
DEFF Research Database (Denmark)
Larsen, Peter Ulrik Vingaard; Christiansen, Peter Leth; Bang, Ole
2004-01-01
The DNA molecule is modeled by a parabola embedded chain with long-range interactions between twisted base pair dipoles. A mechanism for bubble generation is presented and investigated in two different configurations. Using random normally distributed initial conditions to simulate thermal...
Twisted domains in smectic B.sub.2./sub.-phase under an external electric field
Czech Academy of Sciences Publication Activity Database
Lejček, Lubor
2008-01-01
Roč. 494, - (2008), s. 21-37 ISSN 1542-1406 R&D Projects: GA ČR GA202/05/0431 Institutional research plan: CEZ:AV0Z10100520 Keywords : B 2 -phase * bent-shaped molecules * field-induced structural transitions * twisted structures Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.537, year: 2008
Differential expression of transcription factors Snail, Slug, SIP1, and Twist in ameloblastoma.
Siar, Chong Huat; Ng, Kok Han
2014-01-01
Epithelial-to-mesenchymal transition (EMT) via the mechanism of transcription repression is a crucial process for the induction of invasiveness in many human tumors. Ameloblastoma is a benign odontogenic epithelial neoplasm with a locally infiltrative behavior. Twist, an EMT promoter, has been implicated in its invasiveness. The roles of the other transcription factors remain unclarified. Four transcription factors, namely Snail, Slug, SIP1, and Twist, were examined immunohistochemically in 64 ameloblastoma [18 unicystic (UA), 20 solid/multicystic (SA), 4 desmoplastic (DA), and 22 recurrent (RA)]. All four transcription factors were differentially expressed in ameloblastoma [Snail: n = 60/64 (94%); Slug: n = 21/64 (33%); SIP: n = 18/64 (28%); Twist: n = 26/64 (41%)] (P 0.05). Intracellular protein localization was predominantly nuclear for Snail, cytoplasmic>nuclear for Slug and SIP1, and cytoplasmic/nuclear for Twist. Overexpression of Snail in most subsets (UA = 18/18; SMA = 19/20; DA = 4/4; RA = 19/22) compared with the other transcription factors (P ameloblastoma. Overexpression of Snail in most subsets suggests that this molecule is most likely the prototype transcription factor involved in inducing EMT in the ameloblastoma. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.
RNA-Based TWIST1 Inhibition via Dendrimer Complex to Reduce Breast Cancer Cell Metastasis
Directory of Open Access Journals (Sweden)
James Finlay
2015-01-01
Full Text Available Breast cancer is the leading cause of cancer-related deaths among women in the United States, and survival rates are lower for patients with metastases and/or triple-negative breast cancer (TNBC; ER, PR, and Her2 negative. Understanding the mechanisms of cancer metastasis is therefore crucial to identify new therapeutic targets and develop novel treatments to improve patient outcomes. A potential target is the TWIST1 transcription factor, which is often overexpressed in aggressive breast cancers and is a master regulator of cellular migration through epithelial-mesenchymal transition (EMT. Here, we demonstrate an siRNA-based TWIST1 silencing approach with delivery using a modified poly(amidoamine (PAMAM dendrimer. Our results demonstrate that SUM1315 TNBC cells efficiently take up PAMAM-siRNA complexes, leading to significant knockdown of TWIST1 and EMT-related target genes. Knockdown lasts up to one week after transfection and leads to a reduction in migration and invasion, as determined by wound healing and transwell assays. Furthermore, we demonstrate that PAMAM dendrimers can deliver siRNA to xenograft orthotopic tumors and siRNA remains in the tumor for at least four hours after treatment. These results suggest that further development of dendrimer-based delivery of siRNA for TWIST1 silencing may lead to a valuable adjunctive therapy for patients with TNBC.
The static-light meson spectrum from twisted mass lattice QCD
International Nuclear Information System (INIS)
Jansen, Karl; Michael, Chris; Shindler, Andrea; Wagner, Marc
2008-10-01
We compute the static-light meson spectrum with N f =2 flavours of sea quarks using Wilson twisted mass lattice QCD. We consider five different values for the light quark mass corresponding to 300 MeV PS s mesons. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Adams, R.L.
1993-11-01
This document will establish a working standard for testing optical fiber and unshielded twisted pair cables included in the Lab-wide telecommunications cabling system. The purpose of these standard testing procedures is to deliver to all Sandians a reliable, low-maintenance, state-of-the-art, ubiquitous telecommunications cabling infrastructure capable of satisfying all current and future telecommunication needs.
Left ventricular twist and circumferential strain in dogs with myxomatous mitral valve disease
DEFF Research Database (Denmark)
Zois, Nora Elisabeth; Olsen, N. T.; Moesgaard, S. G.
2013-01-01
During the cardiac cycle, the ventricle undergoes a twisting motion because of the oblique orientation of the left ventricular (LV) myofibers. This can be quantified by speckle-tracking echocardiography (STE). In mitral regurgitation (MR) in humans, the short axis deformation has been suggested...
Teaching with a Technological Twist: Exit Tickets via Twitter in Literacy Classrooms
Amaro-Jiménez, Carla; Hungerford-Kresser, Holly; Pole, Kathryn
2016-01-01
In this article, the authors describe, reflect, and analyze the implementation of a commonly used teaching strategy with a technological twist: exit tickets via Twitter. Longitudinal data collected over the course of three years demonstrated that using Twitter to reinvent a nondigital teaching practice ultimately demonstrated a better…
Quercetin Suppresses Twist to Induce Apoptosis in MCF-7 Breast Cancer Cells.
Directory of Open Access Journals (Sweden)
Santhalakshmi Ranganathan
Full Text Available Quercetin is a dietary flavonoid which exerts anti-oxidant, anti-inflammatory and anti-cancer properties. In this study, we investigated the anti-proliferative effect of quercetin in two breast cancer cell lines (MCF-7 and MDA-MB-231, which differed in hormone receptor. IC50 value (37μM of quercetin showed significant cytotoxicity in MCF-7 cells, which was not observed in MDA-MB-231 cells even at 100μM of quercetin treatment. To study the response of cancer cells to quercetin, with respect to different hormone receptors, both the cell lines were treated with a fixed concentration (40μM of quercetin. MCF-7 cells on quercetin treatment showed more apoptotic cells with G1 phase arrest. In addition, quercetin effectively suppressed the expression of CyclinD1, p21, Twist and phospho p38MAPK, which was not observed in MDA-MB-231 cells. To analyse the molecular mechanism of quercetin in exerting an apoptotic effect in MCF-7 cells, Twist was over-expressed and the molecular changes were observed after quercetin administration. Quercetin effectively regulated the expression of Twist, in turn p16 and p21 which induced apoptosis in MCF-7 cells. In conclusion, quercetin induces apoptosis in breast cancer cells through suppression of Twist via p38MAPK pathway.
Quercetin Suppresses Twist to Induce Apoptosis in MCF-7 Breast Cancer Cells
Ranganathan, Santhalakshmi; Halagowder, Devaraj; Sivasithambaram, Niranjali Devaraj
2015-01-01
Quercetin is a dietary flavonoid which exerts anti-oxidant, anti-inflammatory and anti-cancer properties. In this study, we investigated the anti-proliferative effect of quercetin in two breast cancer cell lines (MCF-7 and MDA-MB-231), which differed in hormone receptor. IC50 value (37μM) of quercetin showed significant cytotoxicity in MCF-7 cells, which was not observed in MDA-MB-231 cells even at 100μM of quercetin treatment. To study the response of cancer cells to quercetin, with respect to different hormone receptors, both the cell lines were treated with a fixed concentration (40μM) of quercetin. MCF-7 cells on quercetin treatment showed more apoptotic cells with G1 phase arrest. In addition, quercetin effectively suppressed the expression of CyclinD1, p21, Twist and phospho p38MAPK, which was not observed in MDA-MB-231 cells. To analyse the molecular mechanism of quercetin in exerting an apoptotic effect in MCF-7 cells, Twist was over-expressed and the molecular changes were observed after quercetin administration. Quercetin effectively regulated the expression of Twist, in turn p16 and p21 which induced apoptosis in MCF-7 cells. In conclusion, quercetin induces apoptosis in breast cancer cells through suppression of Twist via p38MAPK pathway. PMID:26491966
DEFF Research Database (Denmark)
Lascu, Christian; Boldea, Ion; Blaabjerg, Frede
2013-01-01
This paper investigates a permanent magnet synchronous motor drive controlled by a second-order variable structure control technique, known as the super-twisting sliding modes (STSM) control. The STSM controller is designed as a direct torque and flux controller and it works in the stator flux...
Google and the "Twisted Cyber Spy" Affair: US-Chinese Communication in an Age of Globalization
Hartnett, Stephen John
2011-01-01
The "twisted cyber spy" affair began in 2010, when Google was attacked by Chinese cyber-warriors charged with stealing Google's intellectual property, planting viruses in its computers, and hacking the accounts of Chinese human rights activists. In the ensuing international embroglio, the US mainstream press, corporate leaders, and White…
Laminar flow heat transfer studies in a twisted square duct for ...
Indian Academy of Sciences (India)
The problem of fluid flow and heat transfer was studied for flow inside twisted duct of square cross-section. Three-dimensional numerical solutions were obtained for steady fully developed laminar flow and for uniform wall heat flux boundary conditions using commercially available software. Reynolds number range ...
DEFF Research Database (Denmark)
Nairismägi, Maarja-Liisa; Vislovukh, Andrii; Meng, Q
2012-01-01
TWIST1 is a highly conserved basic helix-loop-helix transcription factor that promotes epithelial–mesenchymal transition (EMT). Its misregulation has been observed in various types of tumors. Using the MCF-10A-series of cell lines that recapitulate the early stages of breast cancer formation...
T-system on T-hook: Grassmannian solution and twisted Quantum Spectral Curve
Energy Technology Data Exchange (ETDEWEB)
Kazakov, Vladimir [LPT, École Normale Superieure,24, rue Lhomond 75005 Paris (France); Université Paris-VI,Place Jussieu, 75005 Paris (France); Leurent, Sébastien [Institut de Mathématiques de Bourgogne, UMR 5584 du CNRS, University Bourgogne Franche-Comté,9 avenue Alain Savary, 21000 Dijon (France); Volin, Dmytro [School of Mathematics, Trinity College Dublin,College Green, Dublin 2 (Ireland); Nordita, KTH Royal Institute of Technology and Stockholm University,Roslagstullsbacken 23, SE-106 91 Stockholm (Sweden)
2016-12-13
We propose an efficient grassmannian formalism for solution of bi-linear finite-difference Hirota equation (T-system) on T-shaped lattices related to the space of highest weight representations of superalgebra. The formalism is inspired by the quantum fusion procedure known from the integrable spin chains and is based on exterior forms of Baxter-like Q-functions. We find a few new interesting relations among the exterior forms of Q-functions and reproduce, using our new formalism, the Wronskian determinant solutions of Hirota equations known in the literature. Then we generalize this construction to the twisted Q-functions and demonstrate the subtleties of untwisting procedure on the examples of rational quantum spin chains with twisted boundary conditions. Using these observations, we generalize the recently discovered, in our paper with N. Gromov, AdS/CFT Quantum Spectral Curve for exact planar spectrum of AdS/CFT duality to the case of arbitrary Cartan twisting of AdS S string sigma model. Finally, we successfully probe this formalism by reproducing the energy of gamma-twisted BMN vacuum at single-wrapping orders of weak coupling expansion.
Correlation of twisting motion phase and infantile spasms in high risk infants.
Wang, Y Q; Yang, Z X; Zhu, P; Gu, G X
2016-01-01
The aim of this study was to investigate the correlation of twisting motion phase and infantile spasms in high risk infants. One hundred seventy-eight high-risk newborns experiencing follow-up in the rehabilitation phase were selected and full-body motion quality assessment was performed in the twisting motion phase. The occurrence of infants with infantile spasms after 12 months (corrected age) was statistically analyzed. No clear correlation was found between monotonous movement twisting motion phase and infantile spasms, and spasm synchronized movement had no definite prediction for infantile spasms. The incidence of infant spasm with movement form having spastic synchronized characteristics had significant difference compared with monotonous systemic movement (p spasm-synchronous movement of infantile spasms was 90.9%, the specificity was 96.8%, the positive predictive value was 80%, and the negative predictive value was 98.7%. Spasm synchronized movement had some predictive value for infantile spasms in twisting motion stage. The newborns with this kind of movement form should be checked by regularly ambulatory EEG.
Complex Chemistry on Interstellar Grains
Widicus Weaver, Susanna L.; Kelley, Matthew J.; Blake, Geoffrey A.
Early interstellar chemical models considered complex molecule formation on grains [Allen & Robinson (1977)], but current models assume that simple molecules form on grains and subsequent gas phase ion-molecule reactions produce the more complex species [Ruffle & Herbst (2001), Charnley (2001)]. It has been shown, however, that gas phase ion-molecule reactions are insufficient for the production of such complex organic species as ethanol (CH3CH2OH) and methyl formate (CH3OCHO) [Horn et al. (2004)]. Organics such as acetaldehyde (CH3CHO), ethanol, methyl formate, acetic acid (CH3COOH), and glycolaldehyde (CH2OHCHO) have also been detected in high abundance in regions of grain mantle disruption or evaporation, indicating that these species are formed on grain surfaces [see Chengalur & Kanekar (2003), Bottinelli et al. (2004), Hollis et al. (2001)]. The mechanisms for complex molecule production on grains are clearly much more important, and much more complex, than has been recognized. Recent observational studies of these types of species have offered insight into the mechanisms for their possible grain surface synthesis. The relative hot core abundances of the 2C structural isomers methyl formate, acetic acid, and glycolaldehyde (52:2:1, respectively [Hollis et al. (2001)]) indicate that if they form on grains it is not from kinetically-controlled single-atom addition reactions. Likewise, the 3C aldose sugar, glyceraldehyde (CH2OHCHOHCHO), was not detected in Sgr B2(N-LMH) [Hollis et al. (2004)] while the 3C ketose sugar, dihydroxyacetone (CO(CH2OH)2) was detected in this source [Widicus Weaver & Blake (2005)]. Chemical pathways favoring the more stable carbonates over acids and aldehydes are required to explain these results. Interestingly, all of these species can be formed from reactions involving the abundant grain mantle constituents CO, HCOOH, and CH3OH and their radical precursors. A model has been developed to investigate this type of chemical network, and
Time-varying wing-twist improves aerodynamic efficiency of forward flight in butterflies.
Zheng, Lingxiao; Hedrick, Tyson L; Mittal, Rajat
2013-01-01
Insect wings can undergo significant chordwise (camber) as well as spanwise (twist) deformation during flapping flight but the effect of these deformations is not well understood. The shape and size of butterfly wings leads to particularly large wing deformations, making them an ideal test case for investigation of these effects. Here we use computational models derived from experiments on free-flying butterflies to understand the effect of time-varying twist and camber on the aerodynamic performance of these insects. High-speed videogrammetry is used to capture the wing kinematics, including deformation, of a Painted Lady butterfly (Vanessa cardui) in untethered, forward flight. These experimental results are then analyzed computationally using a high-fidelity, three-dimensional, unsteady Navier-Stokes flow solver. For comparison to this case, a set of non-deforming, flat-plate wing (FPW) models of wing motion are synthesized and subjected to the same analysis along with a wing model that matches the time-varying wing-twist observed for the butterfly, but has no deformation in camber. The simulations show that the observed butterfly wing (OBW) outperforms all the flat-plate wings in terms of usable force production as well as the ratio of lift to power by at least 29% and 46%, respectively. This increase in efficiency of lift production is at least three-fold greater than reported for other insects. Interestingly, we also find that the twist-only-wing (TOW) model recovers much of the performance of the OBW, demonstrating that wing-twist, and not camber is key to forward flight in these insects. The implications of this on the design of flapping wing micro-aerial vehicles are discussed.
Time-varying wing-twist improves aerodynamic efficiency of forward flight in butterflies.
Directory of Open Access Journals (Sweden)
Lingxiao Zheng
Full Text Available Insect wings can undergo significant chordwise (camber as well as spanwise (twist deformation during flapping flight but the effect of these deformations is not well understood. The shape and size of butterfly wings leads to particularly large wing deformations, making them an ideal test case for investigation of these effects. Here we use computational models derived from experiments on free-flying butterflies to understand the effect of time-varying twist and camber on the aerodynamic performance of these insects. High-speed videogrammetry is used to capture the wing kinematics, including deformation, of a Painted Lady butterfly (Vanessa cardui in untethered, forward flight. These experimental results are then analyzed computationally using a high-fidelity, three-dimensional, unsteady Navier-Stokes flow solver. For comparison to this case, a set of non-deforming, flat-plate wing (FPW models of wing motion are synthesized and subjected to the same analysis along with a wing model that matches the time-varying wing-twist observed for the butterfly, but has no deformation in camber. The simulations show that the observed butterfly wing (OBW outperforms all the flat-plate wings in terms of usable force production as well as the ratio of lift to power by at least 29% and 46%, respectively. This increase in efficiency of lift production is at least three-fold greater than reported for other insects. Interestingly, we also find that the twist-only-wing (TOW model recovers much of the performance of the OBW, demonstrating that wing-twist, and not camber is key to forward flight in these insects. The implications of this on the design of flapping wing micro-aerial vehicles are discussed.
Artificial blood-flow controlling effects of inhomogeneity of twisted magnetic fields
International Nuclear Information System (INIS)
Nakagawa, Hidenori; Ohuchi, Mikio
2017-01-01
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. - Highlights: • The principal aim of this research is to contribute to the utilization of the twisted fields for the most effective blood-flow in vivo. • Two newly designed coil systems were used for producing a desirably twisted magnetic field under the measuring domain in the flow channel. • Further, we investigated the magnetohydrodynamic efficiencies of a prototype of a magnetic device, which was converted from use as a commercial alternating magnetic therapy apparatus. • The system was well-constructed with a successful application of a plural exposure coil; therefore, we were able to detect a maximum of induced electromotive force in a fluid of an artificial solution as a substitute for blood. • This new finding demonstrates that the process of blood massotherapy by magnetic stimuli is a therapy for many diseases.
Artificial blood-flow controlling effects of inhomogeneity of twisted magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Nakagawa, Hidenori, E-mail: hnakagawa-tdt@umin.ac.jp; 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. - Highlights: • The principal aim of this research is to contribute to the utilization of the twisted fields for the most effective blood-flow in vivo. • Two newly designed coil systems were used for producing a desirably twisted magnetic field under the measuring domain in the flow channel. • Further, we investigated the magnetohydrodynamic efficiencies of a prototype of a magnetic device, which was converted from use as a commercial alternating magnetic therapy apparatus. • The system was well-constructed with a successful application of a plural exposure coil; therefore, we were able to detect a maximum of induced electromotive force in a fluid of an artificial solution as a substitute for blood. • This new finding demonstrates that the process of blood massotherapy by magnetic stimuli is a therapy for many diseases.
Effect of DNA hairpin loops on the twist of planar DNA origami tiles.
Li, Zhe; Wang, Lei; Yan, Hao; Liu, Yan
2012-01-31
The development of scaffolded DNA origami, a technique in which a long single-stranded viral genome is folded into arbitrary shapes by hundreds of short synthetic oligonucleotides, represents an important milestone in DNA nanotechnology. Recent findings have revealed that two-dimensional (2D) DNA origami structures based on the original design parameters adopt a global twist with respect to the tile plane, which may be because the conformation of the constituent DNA (10.67 bp/turn) deviates from the natural B-type helical twist (10.4 bp/turn). Here we aim to characterize the effects of DNA hairpin loops on the overall curvature of the tile and explore their ability to control, and ultimately eliminate any unwanted curvature. A series of dumbbell-shaped DNA loops were selectively displayed on the surface of DNA origami tiles with the expectation that repulsive interactions among the neighboring dumbbell loops and between the loops and the DNA origami tile would influence the structural features of the underlying tiles. A systematic, atomic force microscopy (AFM) study of how the number and position of the DNA loops influenced the global twist of the structure was performed, and several structural models to explain the results were proposed. The observations unambiguously revealed that the first generation of rectangular shaped origami tiles adopt a conformation in which the upper right (corner 2) and bottom left (corner 4) corners bend upward out of the plane, causing linear superstructures attached by these corners to form twisted ribbons. Our experimental observations are consistent with the twist model predicted by the DNA mechanical property simulation software CanDo. Through the systematic design and organization of various numbers of dumbbell loops on both surfaces of the tile, a nearly planar rectangular origami tile was achieved. © 2011 American Chemical Society
Parametric study on kink instabilities of twisted magnetic flux ropes in the solar atmosphere
Mei, Z. X.; Keppens, R.; Roussev, I. I.; Lin, J.
2018-01-01
Aims: Twisted magnetic flux ropes (MFRs) in the solar atmosphere have been researched extensively because of their close connection to many solar eruptive phenomena, such as flares, filaments, and coronal mass ejections (CMEs). In this work, we performed a set of 3D isothermal magnetohydrodynamic (MHD) numerical simulations, which use analytical twisted MFR models and study dynamical processes parametrically inside and around current-carrying twisted loops. We aim to generalize earlier findings by applying finite plasma β conditions. Methods: Inside the MFR, approximate internal equilibrium is obtained by pressure from gas and toroidal magnetic fields to maintain balance with the poloidal magnetic field. We selected parameter values to isolate best either internal or external kink instability before studying complex evolutions with mixed characteristics. We studied kink instabilities and magnetic reconnection in MFRs with low and high twists. Results: The curvature of MFRs is responsible for a tire tube force due to its internal plasma pressure, which tends to expand the MFR. The curvature effect of toroidal field inside the MFR leads to a downward movement toward the photosphere. We obtain an approximate internal equilibrium using the opposing characteristics of these two forces. A typical external kink instability totally dominates the evolution of MFR with infinite twist turns. Because of line-tied conditions and the curvature, the central MFR region loses its external equilibrium and erupts outward. We emphasize the possible role of two different kink instabilities during the MFR evolution: internal and external kink. The external kink is due to the violation of the Kruskal-Shafranov condition, while the internal kink requires a safety factor q = 1 surface inside the MFR. We show that in mixed scenarios, where both instabilities compete, complex evolutions occur owing to reconnections around and within the MFR. The S-shaped structures in current distributions
Time-Varying Wing-Twist Improves Aerodynamic Efficiency of Forward Flight in Butterflies
Zheng, Lingxiao; Hedrick, Tyson L.; Mittal, Rajat
2013-01-01
Insect wings can undergo significant chordwise (camber) as well as spanwise (twist) deformation during flapping flight but the effect of these deformations is not well understood. The shape and size of butterfly wings leads to particularly large wing deformations, making them an ideal test case for investigation of these effects. Here we use computational models derived from experiments on free-flying butterflies to understand the effect of time-varying twist and camber on the aerodynamic performance of these insects. High-speed videogrammetry is used to capture the wing kinematics, including deformation, of a Painted Lady butterfly (Vanessa cardui) in untethered, forward flight. These experimental results are then analyzed computationally using a high-fidelity, three-dimensional, unsteady Navier-Stokes flow solver. For comparison to this case, a set of non-deforming, flat-plate wing (FPW) models of wing motion are synthesized and subjected to the same analysis along with a wing model that matches the time-varying wing-twist observed for the butterfly, but has no deformation in camber. The simulations show that the observed butterfly wing (OBW) outperforms all the flat-plate wings in terms of usable force production as well as the ratio of lift to power by at least 29% and 46%, respectively. This increase in efficiency of lift production is at least three-fold greater than reported for other insects. Interestingly, we also find that the twist-only-wing (TOW) model recovers much of the performance of the OBW, demonstrating that wing-twist, and not camber is key to forward flight in these insects. The implications of this on the design of flapping wing micro-aerial vehicles are discussed. PMID:23341923
Sustainable production of grain crops for biofuels
Grain crops of the Gramineae are grown for their edible, starchy seeds. Their grain is used directly for human food, livestock feed, and as raw material for many industries, including biofuels. Using grain crops for non-food uses affects the amount of food available to the world. Grain-based biofuel...
Development of Perennial Grain Sorghum
Directory of Open Access Journals (Sweden)
Stan Cox
2018-01-01
Full Text Available Perennial germplasm derived from crosses between Sorghum bicolor and either S. halepense or S. propinquum is being developed with the goal of preventing and reversing soil degradation in the world’s grain sorghum-growing regions. Perennial grain sorghum plants produce subterranean stems known as rhizomes that sprout to form the next season’s crop. In Kansas, breeding perennial sorghum involves crossing S. bicolor cultivars or breeding lines to S. halepense or perennial S. bicolorn × S. halepense breeding lines, selecting perennial plants from F2 or subsequent populations, crossing those plants with S. bicolor, and repeating the cycle. A retrospective field trial in Kansas showed that selection and backcrossing during 2002–2009 had improved grain yields and seed weights of breeding lines. Second-season grain yields of sorghum lines regrowing from rhizomes were similar to yields in the first season. Further selection cycles have been completed since 2009. Many rhizomatous lines that cannot survive winters in Kansas are perennial at subtropical or tropical locations in North America and Africa. Grain yield in Kansas was not correlated with rhizomatousness in either Kansas or Uganda. Genomic regions affecting rhizome growth and development have been mapped, providing new breeding tools. The S. halepense gene pool may harbor many alleles useful for improving sorghum for a broad range of traits in addition to perenniality.
International Nuclear Information System (INIS)
Hastings, I.J.; Scoberg, J.A.; Walden, W.
1979-06-01
Grain growth studies have been carried out on UO 2 to provide data for the fuel modelling program and to evaluate fuel fabricated in commissioning the Mixed Oxide Fuel Fabrication Laboratory at Chalk River Nuclear Laboratories. Fuel examined includes natural UO 2 commercially fabricated from ADU powder for CANDU reactors; natural UO 2 commercially fabricated from AU powder; natural UO 2 from ADU and AU powder, fabricated in the MOFFL; and commercially fabricated UO 2 enriched 1.7, 4.5, and 9.6 wt. percent U-235 in U. Samples were step-annealed in vacuo at 1870-2070 K for up to 32.5 h. All data fit a (grain size)sup(2.5) versus annealing time relationship. Apparent activation energy for grain growth, Q, depends on fuel type and varies from 150+-10 kJ/mol for early AU powder to 360+-10 kJ/mol for pellets from ADU fabricated in the MOFFL. Grain sizes calculated using the laboratory equation in a fuel performance code tend to be greater than those measured in irradiated natural fuel, suggesting irradiation-induced inhibition of grain growth. However, any inhibition is equivalent to that expected for a systematic 5 percent underpredicition in reactor power. (author)
International Nuclear Information System (INIS)
Chen, C-C; You, J-Y; Gau, J-P; Huang, C-E; Chen, Y-Y; Tsai, Y-H; Chou, H-J; Lung, J; Yang, M-H
2015-01-01
Epithelial–mesenchymal transition (EMT) is a critical process for inducing stem-like properties of epithelial cancer cells. However, the role of EMT inducers in hematological malignancies is unknown. Twist1, an EMT inducer necessary for cell migration, has recently been found to have transcriptionally regulatory activity on the expression of Bmi1, and these two are capable of promoting tumorigenesis in a synergized manner. Knowing that Bmi1 expression is essential for maintenance of leukemic stem cells, we speculate that Twist1 might govern the pathogenesis of acute myeloid leukemia (AML) development as well. We found that upregulated Twist1 increased Bmi1 expression in AML and endued leukemic cells a higher proliferative potential and increased resistance to apoptosis. In primary AML samples, there was strong positive correlation between the expression levels of Twist1 and Bmi1. AML patients whose leukemic blasts harbored overexpressed Twist1 had a more aggressive clinical phenotype, but they were more likely to have a better clinical outcome after standard therapy. In vitro studies confirmed that Twist1-overexpressing leukemic cells were more susceptible to cytarabine, but not daunorubicin, cytotoxicity. Our findings suggest that, in a subset of AML patients, Twist1 has a prominent role in the pathogenesis of the disease that leads to unique clinical phenotypes
Maleki, H; Gharehaghaji, A A; Dijkstra, P J
2017-07-01
Electrospinning PLLA solutions from two oppositely charged nozzles gives a triangle of fibers, also called E-triangle, that assemble into yarns at the convergence point. The formed yarn at the E-triangle was taken up by a unit comprising a take up roller and coupled twister plate, which twist rate can be varied. At all twist rates, uniform and smooth fibers without any beads were formed. The apex angle of the deposited fibers at the E-triangle was larger at higher twist rates. By increasing the twist rate from 80rpm to 320rpm the orientation angle of fibers in the yarn changes from 18.8° to 41.5°. Increasing the twist rate revealed a higher polymer crystallinity likely due to the polymer orientation by the applied tension to the fibers. The ultimate strength and modulus of electrospun yarns were higher when prepared at higher twist rates. However, at the highest twist rates, the strength and modulus of electrospun yarns leveled off and even decreased slightly. The results revealed that the mechanical properties not only depend on the polymer crystallinity but also on the alignment of the fibers in the yarn and the angle at which they were deposited. These biodegradable materials are promising materials to be used in a wide range of applications where environmentally friendly products are required. Copyright © 2017 Elsevier Ltd. All rights reserved.
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.
Directory of Open Access Journals (Sweden)
Kumar Akarsh
2018-01-01
Full Text Available In the present study numerical analysis of enhancement in heat transfer characteristics in a double pipe heat exchanger is studied using a holed twisted tape.The twisted tape with a constant twist ratio is inserted in a double pipe heat exchanger. Holes of diameter 1mm, 3 mm and 5 mm were drilled at regular pitch throughout the length of the tape. Numerical modeling of a double pipe heat exchanger with the holed twisted tape was constructed considering hot fluid flowing in the inner pipe and cold fluid through the annulus.Simulation was done for varied mass flow rates of hot fluid in the turbulent condition keeping the mass flow rate of cold fluid being constant. Thermal properties like Outlet temperatures, Nusselt number, overall heat transfer coefficient, heat transfer rate and pressure drop were determined for all the cases. Results indicated that normaltwisted tape without holes performed better than the bare tube. In the tested range of mass flow rates the average Nusselt number and heat transfer rate were increased by 85% and 34% respectively. Performance of Twisted tape with holes was slightly reduced than the normal twisted tape and it deteriorated further for higher values hole diameter. Pressure drop was found to be higher for the holed twisted tape than the normal tape.
Bildsoe, Heidi; Fan, Xiaochen; Wilkie, Emilie E; Ashoti, Ator; Jones, Vanessa J; Power, Melinda; Qin, Jing; Wang, Junwen; Tam, Patrick P L; Loebel, David A F
2016-10-01
TWIST1, a basic helix-loop-helix transcription factor is essential for the development of cranial mesoderm and cranial neural crest-derived craniofacial structures. We have previously shown that, in the absence of TWIST1, cells within the cranial mesoderm adopt an abnormal epithelial configuration via a process reminiscent of a mesenchymal to epithelial transition (MET). Here, we show by gene expression analysis that loss of TWIST1 in the cranial mesoderm is accompanied by a reduction in the expression of genes that are associated with cell-extracellular matrix interactions and the acquisition of mesenchymal characteristics. By comparing the transcriptional profiles of cranial mesoderm-specific Twist1 loss-of-function mutant and control mouse embryos, we identified a set of genes that are both TWIST1-dependent and predominantly expressed in the mesoderm. ChIP-seq was used to identify TWIST1-binding sites in an in vitro model of a TWIST1-dependent mesenchymal cell state, and the data were combined with the transcriptome data to identify potential target genes. Three direct transcriptional targets of TWIST1 (Ddr2, Pcolce and Tgfbi) were validated by ChIP-PCR using mouse embryonic tissues and by luciferase assays. Our findings reveal that the mesenchymal properties of the cranial mesoderm are likely to be regulated by a network of TWIST1 targets that influences the extracellular matrix and cell-matrix interactions, and collectively they are required for the morphogenesis of the craniofacial structures. Copyright © 2016 Elsevier Inc. All rights reserved.
Sticking properties of ice grains
Directory of Open Access Journals (Sweden)
Jongmanns M.
2017-01-01
Full Text Available We study the size dependence of pull-off forces of water ice in laboratory experiments and numerical simulations. To determine the pull-off force in our laboratory experiments, we use a liquid nitrogen cooled centrifuge. Depending on its rotation frequency, spherical ice grains detach due to the centrifugal force which is related to the adhesive properties. Numerical simulations are conducted by means of molecular dynamics simulations of hexagonal ice using a standard coarse-grained water potential. The pull-off force of a single contact between two spherical ice grains is measured due to strain controlled simulations. Both, the experimental study and the simulations reveal a dependence between the pull-off force and the (reduced particle radii, which differ significantly from the linear dependence of common contact theories.
Sticking properties of ice grains
Jongmanns, M.; Kumm, M.; Wurm, G.; Wolf, D. E.; Teiser, J.
2017-06-01
We study the size dependence of pull-off forces of water ice in laboratory experiments and numerical simulations. To determine the pull-off force in our laboratory experiments, we use a liquid nitrogen cooled centrifuge. Depending on its rotation frequency, spherical ice grains detach due to the centrifugal force which is related to the adhesive properties. Numerical simulations are conducted by means of molecular dynamics simulations of hexagonal ice using a standard coarse-grained water potential. The pull-off force of a single contact between two spherical ice grains is measured due to strain controlled simulations. Both, the experimental study and the simulations reveal a dependence between the pull-off force and the (reduced) particle radii, which differ significantly from the linear dependence of common contact theories.
International Nuclear Information System (INIS)
Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.
2012-01-01
Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.
PESTICIDES USE AMONG GRAIN MERCHANTS IN MUBI GRAIN ...
African Journals Online (AJOL)
AGROSEARCH UIL
Key words: Pesticides, food security, grain merchants, storage, perception. INTRODUCTION. Food security in sub-Saharan Africa largely depends upon improved food productivity through the use of sustainable agricultural practices and the reduction of post-harvest losses caused by pests and diseases (Adedire, 2001).
Pesticides Use among Grain Merchants in Mubi Grain Markets of ...
African Journals Online (AJOL)
It is, therefore, recommended that farmers, retailers, distributors and all the pesticide workers should undergo regular training/workshop on the use and safety measures of pesticides. Also multimedia awareness activities in local language should be massively conducted. Key words: Pesticides, food security, grain merchants ...
Applied Thermodynamics: Grain Boundary Segregation
Directory of Open Access Journals (Sweden)
Pavel Lejček
2014-03-01
Full Text Available Chemical composition of interfaces—free surfaces and grain boundaries—is generally described by the Langmuir–McLean segregation isotherm controlled by Gibbs energy of segregation. Various components of the Gibbs energy of segregation, the standard and the excess ones as well as other thermodynamic state functions—enthalpy, entropy and volume—of interfacial segregation are derived and their physical meaning is elucidated. The importance of the thermodynamic state functions of grain boundary segregation, their dependence on volume solid solubility, mutual solute–solute interaction and pressure effect in ferrous alloys is demonstrated.
The Antinutritional Components of Grains
DEFF Research Database (Denmark)
Madsen, Claus Krogh; Brinch-Pedersen, Henrik
2016-01-01
Grains provide humans and farmed animals with a very large proportion of the energy and macro- and micronutrients they need. Unfortunately, grains also contain compounds that interfere with the utilization of the nutrients by animals. These so-called antinutritionals may result in poor resource u......, biotechnology, and food chemistry....... utilization, increased costs in meat production, and even malnourishment in humans. The major antinutritionals are phytate, proteinaceous inhibitors of digestive enzymes, tannins, and nonstarch polysaccharides. For each compound, countermeasures are available in the diverse fields of plant breeding...
Acute impact of pacing at different cardiac sites on left ventricular rotation and twist in dogs.
Directory of Open Access Journals (Sweden)
Zhi-Wen Zhou
Full Text Available We evaluated the acute impact of different cardiac pacing sites on two-dimensional speckle-tracking echocardiography (STE derived left ventricular (LV rotation and twist in healthy dogs.Twelve dogs were used in this study. The steerable pacing electrodes were positioned into right heart through the superior or inferior vena cava, into LV through aorta across the aortic valve. The steerable pacing electrodes were positioned individually in the right atrium (RA, right ventricular apex (RVA, RV outflow tract (RVOT, His bundle (HB, LV apex (LVA and LV high septum (LVS, individual pacing mode was applied at 10 minutes interval for at least 5 minutes from each position under fluoroscopy and ultrasound guidance and at stabilized hemodynamic conditions. LV short-axis images at the apical and basal levels were obtained during sinus rhythm and pacing. Offline STE analysis was performed. Rotation, twist, time to peak rotation (TPR, time to peak twist (TPT, and apical-basal rotation delay (rotational synchronization index, RSI values were compared at various conditions. LV pressure was monitored simultaneously.Anesthetic death occurred in 1 dog, and another dog was excluded because of bad imaging quality. Data from 10 dogs were analyzed. RVA, RVOT, HB, LVA, LVS, RARV (RA+RVA pacing resulted in significantly reduced apical and basal rotation and twist, significantly prolonged apical TPR, TPT and RSI compared to pre-pacing and RA pacing (all P<0.05. The apical and basal rotation and twist values were significantly higher during HB pacing than during pacing at ventricular sites (all P<0.05, except basal rotation at RVA pacing. The apical TPR during HB pacing was significantly shorter than during RVOT and RVA pacing (both P<0.05. The LV end systolic pressure (LVESP was significantly lower during ventricular pacing than during pre-pacing and RA pacing.Our results show that RA and HB pacing results in less acute reduction on LV twist, rotation and LVESP compared
Jain, T.; Lin, H. K.; Lan, C. W.
2018-03-01
The development of grain structures during directional solidification of multi-crystalline silicon (mc-Si) plays a crucial role in the materials quality for silicon solar cells. Three dimensional (3D) modelling of the grain boundary (GB) interaction and evolution based on phase fields by considering anisotropic GB energy and mobility for mc-Si is carried out for the first time to elucidate the process. The energy and mobility of GBs are allowed to depend on misorientation and the GB plane. To examine the correctness of our method, the known the coincident site lattice (CSL) combinations such as (∑ a + ∑ b → ∑ a × b) or (∑ a + ∑ b → ∑ a / b) are verified. We frther discuss how to use the GB normal to characterize a ∑ 3 twin GB into a tilt or a twist one, and show the interaction between tilt and twist ∑ 3 twin GBs. Two experimental scenarios are considered for comparison and the results are in good agreement with the experiments as well as the theoretical predictions.
CSIR Research Space (South Africa)
Nabarro, FRN
1998-11-13
Full Text Available This article shows the differences of two-dimensional polycrystal of a material with a rectangular unit cell with lattice spacing b and b (1 + epsilon), subjected to a uniform external stress sigma. Consider a grain in which the lattice vector...
Concepts on Low Temperature Mechanical Grain Growth
Energy Technology Data Exchange (ETDEWEB)
Sharon, John Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.; Boyce, Brad Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.
2013-11-01
In metals, as grain size is reduced below 100nm, conventional dislocation plasticity is suppressed resulting in improvements in strength, hardness, and wears resistance. Existing and emerging components use fine grained metals for these beneficial attributes. However, these benefits can be lost in service if the grains undergo growth during the component’s lifespan. While grain growth is traditionally viewed as a purely thermal process that requires elevated temperature exposure, recent evidence shows that some metals, especially those with nanocrystalline grain structure, can undergo grain growth even at room temperature or below due to mechanical loading. This report has been assembled to survey the key concepts regarding how mechanical loads can drive grain coarsening at room temperature and below. Topics outlined include the atomic level mechanisms that facilitate grain growth, grain boundary mobility, and the impact of boundary structure, loading scheme, and temperature.
Small Grain Production Pt 2: Growth and Development of Small Grains
Jackson, Lee; Williams, Jack
2006-01-01
Part 2 of the 14-part Small Grain Production Manual describes the stages of small grain growth, including germination, tillering, vegetative growth, stem elongation, heading, flowering, grain filling, growth habit and yield components.
International Nuclear Information System (INIS)
Fitzsimmons, M.R.; Sass, S.L.
1988-01-01
Quantitative X-ray diffraction techniques have been used to determine the atomic structure of the Σ = 5 and 13 [001] twist boundaries in Au with a resolution of 0.09 Angstrom or better. The reciprocal lattices of these boundaries were mapped out using synchrotron radiation. The atomic structures were obtained by testing model structures against the intensity observations with a chi square analysis. The boundary structure were modeled using polyhedra, including octahedra, special configurations of tetrahedra and Archimedian anti-prisms, interwoven together by the boundary symmetry. The results of this work point to the possibility of obtaining general rules for grain boundary structure based on X-ray diffraction observations that give the atomic positions with high resolution
Line bundle twisted chiral de Rham complex and bound states of D-branes on toric manifolds
International Nuclear Information System (INIS)
Parkhomenko, S.E.
2014-01-01
In this note we calculate elliptic genus in various examples of twisted chiral de Rham complex on two-dimensional toric compact manifolds and Calabi–Yau hypersurfaces in toric manifolds. At first the elliptic genus is calculated for the line bundle twisted chiral de Rham complex on a compact smooth toric manifold and K3 hypersurface in P 3 . Then we twist chiral de Rham complex by sheaves localized on positive codimension submanifolds in P 2 and calculate in each case the elliptic genus. In the last example the elliptic genus of chiral de Rham complex on P 2 twisted by SL(N) vector bundle with instanton number k is calculated. In all the cases considered we find the infinite tower of open string oscillator contributions and identify directly the open string boundary conditions of the corresponding bound state of D-branes
DEFF Research Database (Denmark)
Wang, Bangjun; Bailly, Aurélien; Zwiewka, Marta
2013-01-01
Plant architecture is influenced by the polar, cell-to-cell transport of auxin that is primarily provided and regulated by plasma membrane efflux catalysts of the PIN-FORMED and B family of ABC transporter (ABCB) classes. The latter were shown to require the functionality of the FK506 binding...... protein42 TWISTED DWARF1 (TWD1), although underlying mechanisms are unclear. By genetic manipulation of TWD1 expression, we show here that TWD1 affects shootward root auxin reflux and, thus, downstream developmental traits, such as epidermal twisting and gravitropism of the root. Using immunological....... In planta bioluminescence resonance energy transfer analysis was used to verify specific ABC transporter B1 (ABCB1)-TWD1 interaction. Our data support a model in which TWD1 promotes lateral ABCB-mediated auxin efflux via protein-protein interaction at the plasma membrane, minimizing reflux from the root...
International Nuclear Information System (INIS)
Hoeger, K.C.
1990-10-01
Higher-twist effects in point-like photon interactions on hydrogen have been studied in xF-distributions of charged particles for -0.2 2.0 GeV/c. Data were taken with a tagged photon beam with energies between 70 and 170 GeV and a pion/kaon beam at fixed energies of 80 and 140 GeV using the same setup of detectors at the CERN-Ω-spectrometer (WA69 experiment). The pion and kaon interactions were used to obtain an estimate of the hadron-like photon component. A first estimation of Higher-Twist cross sections in photoproduction of mesons at high pT has been obtained that is consistent with QCD-expectations. (orig.) [de
Conoscopic patterns in photonic band gap of cholesteric liquid crystal cells with twist defects
Egorov, R. I.; Kiselev, A. D.
2010-10-01
We investigate theoretically the effects of the angle of incidence on light transmission through cholesteric liquid crystals. The systems are two-layer sandwich structures with a twist defect created by rotation of the one layer about the helical axis. The conoscopic images and polarization-resolved patterns are obtained for thick layers by computing the intensity and the polarization parameters as a function of the incidence angles. In addition to the defect angle-induced rotation of the pictures as a whole, the rings associated with the defect mode resonances are found to shrink to a central point and disappear, as the defect twist angle varies from zero to its limiting value π/2 and beyond.
Volume independence for Yang-Mills fields on the twisted torus
García Pérez, Margarita; González-Arroyo, Antonio; Okawa, Masanori
2014-10-01
We review some recent results related to the notion of volume independence in SU(N) Yang-Mills theories. The topic is discussed in the context of gauge theories living on a d-dimensional torus with twisted boundary conditions. After a brief introduction reviewing the formalism for introducing gauge fields on a torus, we discuss how volume independence arises in perturbation theory. We show how, for appropriately chosen twist tensors, perturbative results to all orders in the 't Hooft coupling depend on a specific combination of the rank of the gauge group (N) and the periods of the torus (l), given by lN2/d, for d even. We discuss the well-known relation to noncommutative field theories and address certain threats to volume independence associated to the occurrence of tachyonic instabilities at one-loop order. We end by presenting some numerical results in 2+1 dimensions that extend these ideas to the nonperturbative domain.
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.)
Twisted statistics and the structure of Lie-deformed Minkowski spaces
Meljanac, D.; Meljanac, S.; Pikutić, D.; Gupta, Kumar S.
2017-11-01
We show that the realizations of noncommutative coordinates that are linear in the Lorentz generators form a closed Lie algebra under certain conditions. The star product and the coproduct for the momentum generators are obtained for these Lie algebras and the corresponding twist satisfies the cocycle and normalization conditions. We also obtain the twisted flip operator and the R -matrix that define the statistics of particles or quantum fields propagating in these noncommutative spacetimes. The Lie algebra obtained in this work contains a special case which has been used in the literature to put bounds on noncommutative parameters from the experimental limits on Pauli forbidden transitions. The general covariant framework presented here is suitable for analyzing the properties of particles or quantum fields at the Planck scale.
Properties of pseudoscalar flavour-singlet mesons from 2+1+1 twisted mass 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; Garcia Ramos, Elena; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Michael, Chris [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Ottnad, Konstantin; Urbach, Carsten; Zimmermann, Falk [Bonn Univ. (Germany). Inst. fuer Strahlen- und Kernphysik
2012-11-15
We study properties of pseudoscalar flavour-singlet mesons from Wilson twisted mass lattice QCD with N{sub f}=2+1+1 dynamical quark flavors. Results for masses are presented at three values of the lattice spacing and light quark masses corresponding to values of the pion mass from 230 MeV to 500 MeV. We briefly discuss scaling effects and the light and strange quark mass dependence of M{sub {eta}}. In addition we present an exploratory study using Osterwalder-Seiler type strange and charm valence quarks. This approach avoids some of the complications of the twisted mass heavy doublet. We present first results for matching valence and unitary actions and a comparison of statistical uncertainties.
Twisted injectivity in projected entangled pair states and the classification of quantum phases
Buerschaper, Oliver
2014-12-01
We introduce a class of projected entangled pair states (PEPS) which is based on a group symmetry twisted by a 3-cocycle of the group. This twisted symmetry is expressed as a matrix product operator (MPO) with bond dimension greater than 1 and acts on the virtual boundary of a PEPS tensor. We show that it gives rise to a new standard form for PEPS from which we construct a family of local Hamiltonians which are gapped, frustration-free and include fixed points of the renormalization group flow. Based on this insight, we advance the classification of 2D gapped quantum spin systems by showing how this new standard form for PEPS determines the emergent topological order of these local Hamiltonians. Specifically, we identify their universality class as DIJKGRAAF-WITTEN topological quantum field theory (TQFT).
Effect of Turbulence on Power for Bend-Twist Coupled Blades
DEFF Research Database (Denmark)
Stäblein, Alexander; Hansen, Morten Hartvig
2016-01-01
that it might be related to the dynamic response of bend-twist coupled blades in turbulent flow. This paper contains estimations of the power curve from nonlinear time simulations, a linear frequency domain based method and a normal distribution weighted average method. It is shown that the frequency domain...... that changes in power due to turbulence are similar for coupled and uncoupled blades. Power gains at low wind speeds are related to the curvature of the steady state power curve. Losses around rated wind speed are caused by the effects of controller switching between partial and full power operation.......Bend-twist coupling of wind turbine blades reduces the structural loads of the turbine but it also results in a decrease of the annual energy production. The main part of the power loss can be mitigated by pretwisting the blade, but some power loss remains and previous studies indicate...
Manifold-splitting regularization, self-linking, twisting, writhing numbers of space-time ribbons
International Nuclear Information System (INIS)
Tze, C.H.
1988-01-01
The authors present an alternative formulation of Polyakov's regularization of Gauss' integral formula for a single closed Feynman path. A key element in his proof of the D = 3 fermi-bose transmutations induced by topological gauge fields, this regularization is linked here with the existence and properties of a nontrivial topological invariant for a closed space ribbon. This self-linking coefficient, an integer, is the sum of two differential characteristics of the ribbon, its twisting and writhing numbers. These invariants form the basis for a physical interpretation of our regularization. Their connection to Polyakov's spinorization is discussed. The authors further generalize their construction to the self-linking, twisting and writhing of higher dimensional d = eta(odd) submanifolds in D = (2eta + 1) space-time
Some relations between twisted K-theory and E8 gauge theory
International Nuclear Information System (INIS)
Mathai, Varghese; Sati, Hisham
2004-01-01
Recently, Diaconescu, Moore and Witten provided a nontrivial link between K-theory and M-theory, by deriving the partition function of the Ramond-Ramond fields of Type IIA string theory from an E8 gauge theory in eleven dimensions. We give some relations between twisted K-theory and M-theory by adapting the method of Diaconescu-Moore-Witten and Moore-Saulina. In particular, we construct the twisted K-theory torus which defines the partition function, and also discuss the problem from the E8 loop group picture, in which the Dixmier-Douady class is the Neveu-Schwarz field. In the process of doing this, we encounter some mathematics that is new to the physics literature. In particular, the eta differential form, which is the generalization of the eta invariant, arises naturally in this context. We conclude with several open problems in mathematics and string theory. (author)
Pressure effect on grain boundary diffusion
International Nuclear Information System (INIS)
Smirnova, E.S.; Chuvil'deev, V.N.
1997-01-01
The influence of hydrostatic pressure on grain boundary diffusion and grain boundary migration in metallic materials is theoretically investigated. The model is suggested that permits describing changes in activation energy of grain boundary self-diffusion and diffusion permeability of grain boundaries under hydrostatic pressure. The model is based on the ideas about island-type structure of grain boundaries as well as linear relationship of variations in grain boundary free volume to hydrostatic pressure value. Comparison of theoretical data with experimental ones for a number of metals and alloys (α-Zr, Sn-Ge, Cu-In with Co, In, Al as diffusing elements) shows a qualitative agreement
Energy Technology Data Exchange (ETDEWEB)
Anikin, I.V. [Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna (Russian Federation); Ivanov, D.Yu. [Sobolev Institute of Mathematics, 630090 Novosibirsk (Russian Federation); Pire, B., E-mail: pire@cpht.polytechnique.f [CPHT, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France); Szymanowski, L. [Soltan Institute for Nuclear Studies, PL-00-681 Warsaw (Poland); Wallon, S. [LPT, Universite Paris-Sud, CNRS, 91405 Orsay (France); UPMC Univ. Paris 06, faculte de physique, 4 place Jussieu, 75252 Paris Cedex 05 (France)
2010-03-21
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 rho{sub T} distribution amplitudes. 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 within these two quite different methods and show that they are identical.
LncRNA expression signatures of twist-induced epithelial-to-mesenchymal transition in MCF10A cells.
Hu, Ping; Yang, Jiajia; Hou, Yixuan; Zhang, Hailong; Zeng, Zongyue; Zhao, Liuyang; Yu, Tenghua; Tang, Xi; Tu, Gang; Cui, Xiaojiang; Liu, Manran
2014-01-01
The epithelial-to-mesenchymal transient (EMT) is associated with tumor metastasis. Twist is one of the key transcription factors for EMT and relates to tumor cell migration. Long non-coding RNAs (lncRNAs) have recently emerged as important regulatory molecules involved in a broad range of biological processes and complicated diseases. However, it is unknown whether a signal network and lncRNAs are involved in Twist-induced EMT program. Taking MCF10A/Twist as a model, more than 99 lncRNAs and 3164 genes are regulated in the Twist-induced EMT process using lncRNA-array and cDNA micro-array. We establish a downstream signal network associated with EMT induced by Twist using bioinformatic analysis (Gene Ontology, pathway analysis) and experimental data. A set of multiple canonical signal pathways (such as WNT, MAPK, JAK/STAT, TGF-β, mTOR, Hedgehog and P53 signaling pathways) and several lncRNAs [such as lncRNA (chr6, 26124411-26139312, +), lncRNA (chr1, 41944445-41949874, -), lncRNA (chr17, 44833874-44834830, +)] are altered in MCF10A/Twist cells. More interestingly, lncRNA (chr17, 44833874-44834830, +), lncRNA (chr17, 21142183-21156578, -), lncRNA (chr6, 26124411-26139312, +) and lncRNA (chr19, 438420-2083745, -) may be involved in regulation or activation of WNT signaling pathway in the Twist-induced EMT process. These findings first determine that Twist contributes to invasion and metastasis by inducing wide-ranging transcriptional and functional changes of lncRNAs and signal pathways in our study. © 2013. Published by Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Traynor, Michael M. [Rice Univ., Houston, TX (United States)
1996-01-01
Experiment 683 at Fermilab Wide Band Photon Laboratory observed events via $\\gamma P \\to jets$ during the 1991-1992 fixed target run. The present analysis attempted to observe the higher-twist subprocess in QCD using that data to measure the $p_\\perp$ spectrum via a clustering algorithm tuned to optimize the distinctive topology of higher-twist events. Results indicate a substantial $k_\\perp$ promotion effect at lower $p_\\perp$ and a significant NLO contribution to the photoproduction.
MAML1 and TWIST1 co-overexpression promote invasion of head and neck squamous cell carcinoma.
Ardalan Khales, Sima; Ebrahimi, Ehsan; Jahanzad, Eisa; Ardalan Khales, Sahar; Forghanifard, Mohammad Mahdi
2018-01-15
Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide with considerable morbidity and mortality. Invasion and metastasis of HNSCC is a complex process involving multiple molecules and signaling pathways. Twist Family BHLH Transcription Factor 1 (TWIST1) and Mastermind-like 1 (MAML1) are essential in induction of epithelial-mesenchymal transition through direct regulation of implicated molecules in cellular adhesion, migration and invasion. Our aim in this study was to assess the clinical significance of MAML1 and TWIST1 expression in HNSCC, and elucidate the probable correlation between these genes to exhibit their possible associations with progression and metastasis of the disease. The gene expression profile of MAML1 and TWIST1 was assessed in fresh tumoral compared to distant tumor-free tissues of 55 HNSCC patients using quantitative real-time Polymerase chain reaction (PCR). Significant overexpression of MAML1 and TWIST1 mRNA was observed in 49.1% and 38.2% (P ˂ 0.05) of tumor specimens, respectively. Overexpression of MAML1 was associated with vascular invasion (P = 0.048). Concomitant overexpression of MAML1 and TWIST1 was significantly correlated to each other (P = 0.004). Co-overexpression of the genes was significantly correlated to the various clinicopathological indices of poor prognosis including depth of tumor invasion (P < 0.01), lymphatic invasion and grade of tumor cell differentiation (P < 0.05). Significant correlation between MAML1 and TWIST1 in HNSCC was revealed. This study was the first report elucidating MAML1 clinical relevance in HNSCC. These new findings suggest an oncogenic role for concomitant expression of MAML1 and TWIST1 genes in HNSCC invasion and metastasis. © 2018 John Wiley & Sons Australia, Ltd.
Grain centre mapping - 3DXRD measurements of average grain characteristics
DEFF Research Database (Denmark)
Oddershede, Jette; Schmidt, Søren; Lyckegaard, Allan
2014-01-01
Three-Dimensional X-ray Diraction (3DXRD) Microscopy is a generic term covering a variety of dierent techniques for characterising the mi- crostructure within the bulk of polycrystalline materials. One strategy | namely grain centre mapping | enables fast measurements of the av- erage characteris......Three-Dimensional X-ray Diraction (3DXRD) Microscopy is a generic term covering a variety of dierent techniques for characterising the mi- crostructure within the bulk of polycrystalline materials. One strategy | namely grain centre mapping | enables fast measurements of the av- erage...... and the closely related boxscan method is given. Both validation experiments and applications for in situ studies of microstructural changes during plastic deformation and crack growth are given. Finally an outlook with special emphasis on coupling the measured results with modelling is given....
Study of a twisted ATLAS SCT Barrel deformation as revealed by a photogrammetric survey
Dobson, E; Heinemann, F; Karagoz-Unel, M
2007-01-01
A photogrammetry survey on the SCT barrels was performed as an engineering check on the structure of the ATLAS Semiconductor Tracker (SCT) shortly after construction. Analysis of the data obtained revealed small scale elliptical deformation as well as a twist of the structure. The results of the survey are presented as well as interpolation of the measured targets to the module positions and a comparison with track based alignment measurements.
γ*→ρT impact factor with twist three accuracy
International Nuclear Information System (INIS)
Anikin, I. V.; Ivanov, D. Yu.; Pire, B.; Szymanowski, L.; Wallon, S.
2009-01-01
We evaluate the impact factor of the transition γ*→ρ T taking into account the twist 3 contributions. We show that a gauge invariant expression is obtained with the help of QCD equations of motion. Our results are free of end-point singularities. This opens the way to a consistent treatment of factorization for exclusive processes with a transversally polarized vector meson.
Tunable hybrid optical modes in a bounded cholesteric liquid crystal with a twist defect
Pyatnov, Maxim V.; Vetrov, Stepan Ya.; Timofeev, Ivan V.
2018-03-01
Coupling between the defect mode of a cholesteric liquid crystal and the localized mode of a cholesteric liquid crystal-phase plate-metal structure is theoretically demonstrated. It is shown that the transmittance spectrum can be tuned by changing the twist-defect angle and helix pitch, which are governed by external factors. The spectra for different circular polarizations of the incident light are different; specifically, at the nondiffracting polarization, there is no defect-mode transmittance peak.
Czech Academy of Sciences Publication Activity Database
del Corro, Elena; Peňa-Álvarez, Miriam; Sato, K.; Morales-García, A.; Bouša, Milan; Mračko, Michal; Kolman, Radek; Pacáková, Barbara; Kavan, Ladislav; Kalbáč, Martin; Frank, Otakar
2017-01-01
Roč. 95, č. 8 (2017), č. článku 085138. ISSN 2469-9950 R&D Projects: GA ČR GA14-15357S; GA MŠk LL1301; GA ČR GA16-03823S Institutional support: RVO:61388955 ; RVO:61388998 ; RVO:68378271 Keywords : twisted bilayer graphene * tuning * silicon Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 3.836, year: 2016
String theory flux vacua on twisted tori and generalized complex geometry
International Nuclear Information System (INIS)
Andriot, David
2010-01-01
This thesis is devoted to the study of flux vacua of string theory, with the ten-dimensional space-time split into a four-dimensional maximally symmetric space-time, and a six-dimensional internal manifold M, taken to be a solv-manifold (twisted torus). Such vacua are of particular interest when trying to relate string theory to supersymmetric (SUSY) extensions of the standard model of particles, or to cosmological models. For SUSY solutions of type II supergravities, allowing for fluxes on M helps to solve the moduli problem. Then, a broader class of manifolds than just the Calabi-Yau can be considered for M, and a general characterization is given in terms of Generalized Complex Geometry: M has to be a Generalized Calabi-Yau (GCY). A subclass of solv-manifolds have been proven to be GCY, so we look for solutions with such M. To do so, we use an algorithmic resolution method. Then we focus on specific new solutions: those admitting an intermediate SU(2) structure. A transformation named the twist is then discussed. It relates solutions on torus to solutions on solv-manifolds. Working out constraints on the twist to generate solutions, we can relate known solutions, and find a new one. We also use the twist to relate flux vacua of heterotic string. Finally we consider ten-dimensional de Sitter solutions. Looking for such solutions is difficult, because of several problems among which the breaking of SUSY. We propose an Ansatz for SUSY breaking sources which helps to overcome these difficulties. We give an explicit solution on a solv-manifold, and discuss partially its four-dimensional stability. (author)
Slavnov and Gaudin-Korepin Formulas for Models without U(1) Symmetry: the Twisted XXX Chain
Belliard, Samuel; Pimenta, Rodrigo A.
2015-12-01
We consider the XXX spin-1/2 Heisenberg chain on the circle with an arbitrary twist. We characterize its spectral problem using the modified algebraic Bethe anstaz and study the scalar product between the Bethe vector and its dual. We obtain modified Slavnov and Gaudin-Korepin formulas for the model. Thus we provide a first example of such formulas for quantum integrable models without U(1) symmetry characterized by an inhomogenous Baxter T-Q equation.
STUDY OF DRYING KINETICS OF BUCKWHEAT IN THE DRYER WITH TWISTED COOLANT FLOWS
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S. T. Antipov
2014-01-01
Full Text Available Summary. Drying of buckwheat seeds is one of the most important stages of preparation of this raw material to the subsequent process of its processing. The nutritional value and quality indicators of the finished product depend on the mode of drying and are the result of structural, mechanical, biological and physico-mechanical transformations of substances. Technological modes of drying buckwheat seeds depend on the content of water and have a significant effect on the change of carbohydrates, protein denaturation, oxidation of lipids, changes of vitamins and organic acids. A new method of drying buckwheat and designed and constructed an experimental dryer with adjustable swirling flow of the coolant is proposed. For the study of the experiments and to determine the optimal mode of drying was used central composite rotatable uniforms - planning and selected full factorial experiment. The kinetics of drying and heat buckwheat in the device with twisted coolant flow was investigated. The influence of various parameters on the drying kinetics of buckwheat in the dryer with twisted coolant flow was invesigated. Presents the results of experimental studies, buckwheat drying in the dryer with twisted coolant flows. On the basis of experimental data and their statistical processing was obtained a mathematical model that adequately describes the process of drying buckwheat in the device with twisted coolant flow. The character of changes in the criteria optimization depending on the input factors was determined. The results of the mathematical model will be useful to a wide range of professionals involved in drying buckwheat, as well as for the calculation and design of modern drying - boiler systems.
On the twisted N=2 superconformal structure in 2d gravity coupled to matter
International Nuclear Information System (INIS)
Panda, S.; Roy, S.
1993-05-01
It is shown that the two dimensional gravity, described either in the conformal gauge (Liouville theory) or in the light cone gauge, when coupled to matter processes an infinite number of twisted N=2 superconformal symmetries. The central charges of the N=2 algebra for the two gauge choices are in general different. Further, it is argued that the physical states in the light cone gauge theory can be obtained from the Liouville theory by a field redefinition. (author). 18 refs
HOMFLY for twist knots and exclusive Racah matrices in representation [333
Morozov, A.
2018-03-01
Next step is reported in the program of Racah matrices extraction from the differential expansion of HOMFLY polynomials for twist knots: from the double-column rectangular representations R = [ rr ] to a triple-column and triple-hook R = [ 333 ]. The main new phenomenon is the deviation of the particular coefficient f[ 332 ][ 21 ] from the corresponding skew dimension, what opens a way to further generalizations.
Czech Academy of Sciences Publication Activity Database
Pajer, Petr; Pečenka, Vladimír; Karafiát, Vít; Králová, Jarmila; Hořejší, Zuzana; Dvořák, Michal
2003-01-01
Roč. 22, č. 5 (2003), s. 665-673 ISSN 0950-9232 R&D Projects: GA ČR GV301/98/K042; GA ČR GA204/00/0554 Institutional research plan: CEZ:AV0Z5052915 Keywords : twist gene * MAV retrovirus * nephroblastoma Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.495, year: 2003
Twisted Spectral Triple for the Standard Model and Spontaneous Breaking of the Grand Symmetry
Energy Technology Data Exchange (ETDEWEB)
Devastato, Agostino, E-mail: agostino.devastato@na.infn.it; Martinetti, Pierre, E-mail: martinetti@dima.unige.it [Università di Napoli Federico II, Dipartimento di Fisica (Italy)
2017-03-15
Grand symmetry models in noncommutative geometry, characterized by a non-trivial action of functions on spinors, have been introduced to generate minimally (i.e. without adding new fermions) and in agreement with the first order condition an extra scalar field beyond the standard model, which both stabilizes the electroweak vacuum and makes the computation of the mass of the Higgs compatible with its experimental value. In this paper, we use a twist in the sense of Connes-Moscovici to cure a technical problem due to the non-trivial action on spinors, that is the appearance together with the extra scalar field of unbounded vectorial terms. The twist makes these terms bounded and - thanks to a twisted version of the first-order condition that we introduce here - also permits to understand the breaking to the standard model as a dynamical process induced by the spectral action, as conjectured in [24]. This is a spontaneous breaking from a pre-geometric Pati-Salam model to the almost-commutativegeometryofthestandardmodel,withtwoHiggs-likefields: scalar and vector.
Twist-3 fragmentation effects for ALT in light hadron production from proton-proton collisions
Koike, Y.; Pitonyak, D.; Takagi, Y.; Yoshida, S.
2016-01-01
We compute the contribution from the twist-3 fragmentation function for light hadron production in collisions between transversely and longitudinally polarized protons, i.e., p↑ p → → h X, which can cause a double-spin asymmetry (DSA) ALT. This is a naïve T-even twist-3 observable that we analyze in collinear factorization using both Feynman gauge and lightcone gauge as well as give a general proof of color gauge invariance. So far only twist-3 effects in the transversely polarized proton have been studied for ALT in p↑ p → → h X. However, there are indications that the naïve T-odd transverse single-spin asymmetry (SSA) AN in p↑ p → h X is dominated not by such distribution effects but rather by a fragmentation mechanism. Therefore, one may expect similarly that the fragmentation contribution is important for ALT. Given possible plans at RHIC to measure this observable, it is timely to provide a calculation of this term.
Order reconstruction in inverse twisted nematic cell with an applied electric field
Sun, Yang; Ye, Wenjiang; Zhang, Zhidong
2016-05-01
Order reconstruction in an inverse twisted nematic (ITN) liquid crystal cell with an applied electric field is investigated based on Landau-de Gennes theory and the two-dimensional finite-difference iterative method. Twice eigenvalue exchange in three-axis layer configuration, thrice eigenvalue exchange in four-axis layer configuration, and negative order parameter uniaxial twisted state exist in this cell, which can be described by the order parameter tensor Q in equilibrium state. The twice eigenvalue exchange also has two degenerate configurations with reduced electric field E from 0.8 to 2.8 in 10ξ cell (ξ is the biaxial correlation length). Moreover, two critical cell gaps dc* * = 7 ξ and dc* = 12 ξ are included in the study of the ITN cell. When d ≤ dc* * , only the eigenvalue change state exists. When d ≥ dc*, only a positive order parameter uniaxial twisted state exists near the threshold electric field. When dc* * concept of eigenvalue exchange.
Trbojevic, Nina; Read, Daniel J; Nagaraj, Mamatha
2017-11-01
A detailed investigation of the thermal and dielectric properties of a series of binary mixtures exhibiting the nematic (N) and twist-bend nematic (N_{TB}) liquid crystal phases is presented. The mixtures consist of an achiral, dimeric liquid crystal CB7CB, which forms the nematic and twist-bend nematic phases, and a calamitic liquid crystal 5CB, which shows the nematic phase. As the concentration of the calamitic liquid crystal is increased, the transition temperatures decrease linearly, and the width of the nematic phase increases. The enthalpies of phase transitions obtained from DSC measurements show that on increasing the concentration of 5CB in the binary mixtures, the enthalpy associated with the N-N_{TB} phase transitions reduces considerably compared to a clear first-order N-N_{TB} transition in pure CB7CB. The real and imaginary parts of the dielectric permittivity are measured as a function of frequency from 100 Hz to 2 MHz in the nematic and twist-bend nematic phases in planar and homeotropic devices. A significant decrease in the average dielectric permittivity as a function of temperature for mixtures forming the N_{TB} phase is observed. Measurements of the imaginary part of the dielectric permittivity show a relaxation peak in the measured frequency window for all of the mixtures exhibiting the N_{TB} phase. The activation energy associated with this relaxation process is calculated and is shown to remain constant irrespective of the composition of the mixtures.
Duality in twisted N=4 supersymmetric gauge theories in four dimensions
Labastida, J.M.F.; Lozano, Carlos
1999-01-01
We consider a twisted version of the four-dimensional N=4 supersymmetric Yang-Mills theory with gauge groups SU(2) and SO(3), and bare masses for two of its chiral multiplets, thereby breaking N=4 down to N=2. Using the wall-crossing technique introduced by Moore and Witten within the u-plane approach to twisted topological field theories, we compute the partition function and all the topological correlation functions for the case of simply-connected spin four-manifolds of simple type. By including 't Hooft fluxes, we analyse the properties of the resulting formulae under duality transformations. The partition function transforms in the same way as the one first presented by Vafa and Witten for another twist of the N=4 supersymmetric theory in their strong coupling test of S-duality. Both partition functions coincide on K3. The topological correlation functions turn out to transform covariantly under duality, following a simple pattern which seems to be inherent in a general type of topological quantum field ...
DNMT3A mutation leads to leukemic extramedullary infiltration mediated by TWIST1
Directory of Open Access Journals (Sweden)
Jie Xu
2016-10-01
Full Text Available Abstract Background DNMT3A mutations are frequently discovered in acute myeloid leukemia (AML, associated with poor outcome. Recently, a relapse case report of AML extramedullary disease has showed that AML cells harboring DNMT3A variation were detected in the cerebral spinal fluid. However, whether a causal relationship exists between DNMT3A mutation (D3Amut and extramedullary infiltration (EMI is unclear. Methods We took advantage of DNMT3A (R882C mutation-carrying AML cell strain, that is, OCI-AML3, assessing its migration ability in vitro and in vivo. By RNA interfering technology and a xenograft mouse model, we evaluated the effect of DNMT3A mutation on cell mobility and explored the possible mechanism. Results OCI-AML3 displayed extraordinary migration ability in vitro and infiltrated into meninges of NOD/SCID mice after intravenous transfusion. We found that this leukemic migration or infiltration capacity was significantly compromised by the knockdown of DNMT3A mutant. Notably, TWIST1, a critical inducer of epithelial–mesenchymal transition, which underlies the metastasis of carcinomas, was highly expressed in association with R882 mutations. Abrogation of TWIST1 in DNMT3A mutated cells considerably weakened their mobility or infiltration. Conclusions Our results demonstrate that D3Amut in OCI-AML3 strain enhances leukemic aggressiveness by promoting EMI process, which is partially through upregulating TWIST1.
The Effect of Non-Harmonic Active Twist Actuation on BVI Noise
Fogarty, David E.; Wilbur, Matthew L.; Sekula, Martin K.
2011-01-01
The results of a computational study examining the effects of non-harmonic active-twist control on blade-vortex interaction (BVI) noise for the Apache Active Twist Rotor are presented. Rotor aeroelastic behavior was modeled using the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics code and the rotor noise was predicted using the acoustics code PSU-WOPWOP. The application of non-harmonic active-twist inputs to the main rotor blade system comprised three parameters: azimuthal location to start actuation, azimuthal duration of actuation, and magnitude of actuation. The acoustic analysis was conducted for a single low-speed flight condition of advance ratio mu=0.14 and shaft angle-of-attack, a(sub s)=+6deg. BVI noise levels were predicted on a flat plane of observers located 1.1 rotor diameters beneath the rotor. The results indicate significant reductions of up to 10dB in BVI noise using a starting azimuthal location for actuation of 90?, an azimuthal duration of actuation of 90deg, and an actuation magnitude of +1.5 ft-lb.
Twist2 Is Upregulated in Early Stages of Repair Following Acute Kidney Injury
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Elizabeth A. Grunz-Borgmann
2017-02-01
Full Text Available The aging kidney is a marked by a number of structural and functional changes, including an increased susceptibility to acute kidney injury (AKI. Previous studies from our laboratory have shown that aging male Fischer 344 rats (24 month are more susceptible to apoptosis-mediated injury than young counterparts. In the current studies, we examined the initial injury and early recovery phases of mercuric chloride-induced AKI. Interestingly, the aging kidney had decreased serum creatinine compared to young controls 1 day following mercuric chloride injury, but by day 4, serum creatinine was significantly elevated, suggesting that the aging kidney did not recover from injury. This conclusion is supported by the findings that serum creatinine and kidney injury molecule-1 (Kim-1 gene expression remain elevated compared to young controls at 10 days post-injury. To begin to elucidate mechanism(s underlying dysrepair in the aging kidney, we examined the expression of Twist2, a helix-loop-helix transcription factor that may mediate renal fibrosis. Interestingly, Twist2 gene expression was elevated following injury in both young and aged rats, and Twist2 protein expression is elevated by mercuric chloride in vitro.
Twisted injectivity in projected entangled pair states and the classification of quantum phases
Energy Technology Data Exchange (ETDEWEB)
Buerschaper, Oliver, E-mail: obuerschaper@perimeterinstitute.ca
2014-12-15
We introduce a class of projected entangled pair states (PEPS) which is based on a group symmetry twisted by a 3-cocycle of the group. This twisted symmetry is expressed as a matrix product operator (MPO) with bond dimension greater than 1 and acts on the virtual boundary of a PEPS tensor. We show that it gives rise to a new standard form for PEPS from which we construct a family of local Hamiltonians which are gapped, frustration-free and include fixed points of the renormalization group flow. Based on this insight, we advance the classification of 2D gapped quantum spin systems by showing how this new standard form for PEPS determines the emergent topological order of these local Hamiltonians. Specifically, we identify their universality class as DIJKGRAAF–WITTEN topological quantum field theory (TQFT). - Highlights: • We introduce a new standard form for projected entangled pair states via a twisted group symmetry which is given by nontrivial matrix product operators. • We construct a large family of gapped, frustration-free Hamiltonians in two dimensions from this new standard form. • We rigorously show how this new standard form for low energy states determines the emergent topological order.
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...
Vibration response comparison of twisted shrouded blades using different impact models
Xie, Fangtao; Ma, Hui; Cui, Can; Wen, Bangchun
2017-06-01
On the basis of our previous work (Ma et al., 2016, Journal of Sound and Vibration, 378, 92-108) [36], an improved analytical model (IAM) of a rotating twisted shrouded blade with stagger angle simulated by flexible beam with a tip-mass is established based on Timoshenko beam theory, whose effectiveness is verified using finite element (FE) method. The effects of different parameters such as shroud gaps, contact stiffness, stagger angles and twist angels on the vibration responses of the shrouded blades are analyzed using two different impact models where the adjacent two shrouded blades are simulated by massless springs in impact model 1 (IM1) and those are simulated by Timoshenko beam in impact model 2 (IM2). The results indicate that two impact models agree well under some cases such as big shroud gaps and small contact stiffness due to the small vibration effects of adjacent blades, but not vice versa under the condition of small shroud gaps and big contact stiffness. As for IM2, the resonance appears because the limitation of the adjacent blades is weakened due to their inertia effects, however, the resonance does not appear because of the strong limitation of the springs used to simulate adjacent blades for IM1. With the increase of stagger angles and twist angles, the first-order resonance rotational speed increases due to the increase of the dynamic stiffness under no-impact condition, and the rotational speeds of starting impact and ending impact rise under the impact condition.