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1

Can Gravity Probe B usefully constrain torsion gravity theories?  

E-print Network

In most theories of gravity involving torsion, the source for torsion is the intrinsic spin of matter. Since the spins of fermions are normally randomly oriented in macroscopic bodies, the torsion generated is normally negligible. However, in a recent paper, Mao et al. point out that there is a class of theories in which the angular momentum of macroscopic spinning bodies generates a significant amount of torsion. They argue that by the principle of action equals reaction, one would expect the angular momentum of test bodies to couple to a background torsion field, and therefore the precession of the GPB gyroscopes should be affected in these theories by the torsion generated by the Earth. We show that in fact the principle of action equals reaction does not apply to these theories. We examine in detail a generalization of the Hayashi-Shirafuji theory suggested by Mao et al. called Einstein-Hayashi-Shirafuji theory. There are a variety of different versions of this theory, depending on the precise form of the coupling to matter chosen for the torsion. We show that for any coupling to matter that is compatible with the spin transport equation postulated by Mao et al., the theory has either ghosts or an ill-posed initial value formulation. These theoretical problems can be avoided by specializing the parameters of the theory and in addition choosing the standard minimal coupling to matter of the torsion tensor. This yields a consistent theory, but one in which the action equals reaction principle is violated, and in which the angular momentum of the gyroscopes does not couple to the Earth's torsion field. Thus, the Einstein-Hayashi-Shirafuji theory does not predict a detectable torsion signal for Gravity Probe B. There may be other torsion theories which do.

Eanna E. Flanagan; Eran Rosenthal

2007-05-14

2

35. VERTICAL AND TORSIONAL MOTION FROM EAST TOWER SHOWING ANGULAR ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

35. VERTICAL AND TORSIONAL MOTION FROM EAST TOWER SHOWING ANGULAR DISTORTION APPROACHING 45 DEGREES WITH LAMP POSTS APPEARING TO BE AT EIGHT ANGLES, 7 NOVEMBER 1940, FROM 16MN FILM SHOT BY PROFESSOR F.B. FARQUHARSON, UNIVERSITY OF WASHINGTON. (LABORATORY STUDIES ON THE TACOMA NARROWS BRIDGE, AT UNIVERSITY OF WASHINGTON SEATTLE: UNIVERSITY OF WASHINGTON, DEPARTMENT OF CIVIL ENGINEERING, 1941) - Tacoma Narrows Bridge, Spanning Narrows at State Route 16, Tacoma, Pierce County, WA

3

Feedback control of torsion balance in measurement of gravitational constant G with angular acceleration method  

SciTech Connect

The performance of the feedback control system is of central importance in the measurement of the Newton's gravitational constant G with angular acceleration method. In this paper, a PID (Proportion-Integration-Differentiation) feedback loop is discussed in detail. Experimental results show that, with the feedback control activated, the twist angle of the torsion balance is limited to 7.3×10{sup ?7} rad /?( Hz ) at the signal frequency of 2?mHz, which contributes a 0.4 ppm uncertainty to the G value.

Quan, Li-Di [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China) [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); School of Automation, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Xue, Chao; Shao, Cheng-Gang; Yang, Shan-Qing; Tu, Liang-Cheng; Luo, Jun, E-mail: junluo@mail.hust.edu.cn [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)] [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang, Yong-Ji [School of Automation, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)] [School of Automation, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2014-01-15

4

Feedback control of torsion balance in measurement of gravitational constant G with angular acceleration method  

NASA Astrophysics Data System (ADS)

The performance of the feedback control system is of central importance in the measurement of the Newton's gravitational constant G with angular acceleration method. In this paper, a PID (Proportion-Integration-Differentiation) feedback loop is discussed in detail. Experimental results show that, with the feedback control activated, the twist angle of the torsion balance is limited to 7.3× 10^{-7}rad/ sqrt{Hz} at the signal frequency of 2 mHz, which contributes a 0.4 textrm {ppm} uncertainty to the G value.

Quan, Li-Di; Xue, Chao; Shao, Cheng-Gang; Yang, Shan-Qing; Tu, Liang-Cheng; Wang, Yong-Ji; Luo, Jun

2014-01-01

5

The torsion cosmology in Kaluza–Klein theory  

SciTech Connect

We have studied the torsion cosmology model in Kaluza–Klein theory. We considered two simple models in which the torsion vectors are A{sub ?} = (?,0,0,0) and A{sub ?} = a(t){sup 2}(0,?,?,?), respectively. For the first model, the accelerating expansion of the Universe can be not explained without dark energy which is similar to that in the standard cosmology. But for the second model, we find that without dark energy the effect of torsion can give rise to the accelerating expansion of the universe and the alleviation of the well-known age problem of the three old objects for appropriated value of the model parameter ?. These outstanding features of the second torsion cosmology model have been supported by the Type Ia supernovae (SNIa) data.

Chen, Songbai; Jing, Jiliang, E-mail: csb3752@163.com, E-mail: jljing@hunnu.edu.cn [Institute of Physics and Department of Physics, Hunan Normal University, Changsha, Hunan 410081 (China)

2009-09-01

6

Continuity of the torsionless limit as a selection rule for gravity theories with torsion  

E-print Network

While one can in principle augment gravity theory with torsion, it is generally thought that any such torsion affects would be too small to be of consequence. Here we show that this cannot in general be the case. We show that the limit of vanishing torsion is not necessarily a continuous one, with the theory obtained in the limit not necessarily coinciding with the theory in which torsion had never been present at all. However, for a standard torsion tensor that is antisymmetric in two of its indices we have found two cases in which the vanishing torsion limit is in fact continuous, namely Einstein gravity and conformal gravity. For other gravity theories of common interest to possess a continuous limit the torsion tensor would need to be antisymmetric in all three of its indices.

Luca Fabbri; Philip D. Mannheim

2014-05-06

7

Thermal Properties of SiCp/Al Composites Consolidated by Equal Channel Angular Pressing and Torsion  

NASA Astrophysics Data System (ADS)

Powder mixture of pure Al and oxidized SiC was consolidated into SiCp/Al composites by equal channel angular pressing and torsion (ECAP-T). The influences of several parameters on the thermal expansions, the thermal conductivities, and the recrystallization temperatures of the as-consolidated composites were studied. These parameters are the number of ECAP-T passes (1, 2, and 4), the content of SiC (10, 20, and 40 wt.%), and the fabrication temperature (150, 250, and 350 °C). The results show that increasing the number of ECAP-T passes has a positive effect on depressing the coefficient of thermal expansion (CTE) of the composite within a certain temperature range, since the total variation amplitude of the CTE is enlarged. The CTE can also be decreased by increasing the content of SiC. The number of ECAP-T passes and the contents of SiC in the composites are both positively related with the thermal conductivity of the composites. No direct relationship between the fabrication temperature and the thermal properties was detected. However, the composite fabricated at too low temperature (150 °C) can not obtain full densification, leading to the appearance of low CTE and thermal conductivity. Finally, when the number of ECAP-T passes is elevated from 2 to 4, the recrystallization temperature of the composite has an obvious declination.

Qian, Chen-hao; Li, Ping; Xue, Ke-min

2014-11-01

8

Constraining torsion with Gravity Probe B  

SciTech Connect

It is well-entrenched folklore that all torsion gravity theories predict observationally negligible torsion in the solar system, since torsion (if it exists) couples only to the intrinsic spin of elementary particles, not to rotational angular momentum. We argue that this assumption has a logical loophole which can and should be tested experimentally, and consider nonstandard torsion theories in which torsion can be generated by macroscopic rotating objects. In the spirit of action=reaction, if a rotating mass like a planet can generate torsion, then a gyroscope would be expected to feel torsion. An experiment with a gyroscope (without nuclear spin) such as Gravity Probe B (GPB) can test theories where this is the case. Using symmetry arguments, we show that to lowest order, any torsion field around a uniformly rotating spherical mass is determined by seven dimensionless parameters. These parameters effectively generalize the parametrized post-Newtonian formalism and provide a concrete framework for further testing Einstein's general theory of relativity (GR). We construct a parametrized Lagrangian that includes both standard torsion-free GR and Hayashi-Shirafuji maximal torsion gravity as special cases. We demonstrate that classic solar system tests rule out the latter and constrain two observable parameters. We show that Gravity Probe B is an ideal experiment for further constraining nonstandard torsion theories, and work out the most general torsion-induced precession of its gyroscope in terms of our torsion parameters.

Mao Yi; Guth, Alan H.; Cabi, Serkan [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Tegmark, Max [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); MIT Kavli Institute for Astrophysics and Space Research, Cambridge, Massachusetts 02139 (United States)

2007-11-15

9

Torsion waves in metric-affine field theory  

E-print Network

The approach of metric-affine field theory is to define spacetime as a real oriented 4-manifold equipped with a metric and an affine connection. The 10 independent components of the metric tensor and the 64 connection coefficients are the unknowns of the theory. We write the Yang-Mills action for the affine connection and vary it both with respect to the metric and the connection. We find a family of spacetimes which are stationary points. These spacetimes are waves of torsion in Minkowski space. We then find a special subfamily of spacetimes with zero Ricci curvature; the latter condition is the Einstein equation describing the absence of sources of gravitation. A detailed examination of this special subfamily suggests the possibility of using it to model the neutrino. Our model naturally contains only two distinct types of particles which may be identified with left-handed neutrinos and right-handed antineutrinos.

Alastair D. King; Dmitri Vassiliev

2000-12-13

10

THEORIES FOR ANGULAR DISTRIBUTIONS IN LOW ENERGY NUCLEAR REACTIONS  

Microsoft Academic Search

A series of six lectures presented at the Lawrence Radiation Laboratory ; on angular distributions in nuclear reactions are given. Topics covered include ; a survey of reaction mechanisms, Born approximation for direct interaction ; theory, semiclassical approximation for direct interaction, distorted wave ; analysis and direct surface interactions, the general theory of angular ; correlation, and interpretation of inelastic

S. A. Moszkowski; J. Benveniste; E. H. eds. Schwarcz

1962-01-01

11

Parallel spinors and connections with skewsymmetric torsion in string theory \\Lambda  

E-print Network

Parallel spinors and connections with skew­symmetric torsion in string theory \\Lambda Thomas is of importance in string theory, since they are associated with some string solitons (BPS solitons) [42­ plications in the exploration of perturbative and non­perturbative properties of string theory. An important

Friedrich, Thomas

12

Scalar-torsion mode in a cosmological model of the Poincaré gauge theory of gravity  

SciTech Connect

We investigate the scalar-torsion mode in a cosmological model of the Poincaré gauge theory of gravity. We treat the geometric effect of torsion as an effective quantity, which behaves like dark energy, and study the effective equation of state (EoS) of the model. We concentrate on two cases with the constant curvature solution and positive kinetic energy, respectively. In the former, we find that the torsion EoS has different values in the various stages of the universe. In particular, it behaves like the radiation (matter) EoS of w{sub r} = 1/3 (w{sub m} = 0) in the radiation (matter) dominant epoch, while in the late time the torsion density is supportive for the accelerating universe. In the latter, our numerical analysis shows that in general the EoS has an asymptotic behavior in the high redshift regime, while it could cross the phantom divide line in the low redshift regime.

Tseng, Huan-Hsin; Lee, Chung-Chi; Geng, Chao-Qiang, E-mail: d943335@oz.nthu.edu.tw, E-mail: g9522545@oz.nthu.edu.tw, E-mail: geng@phys.nthu.edu.tw [Department of Physics, National Tsing Hua University, Hsinchu, 300 Taiwan (China)

2012-11-01

13

Torsion waves in metric{ane eld theory Alastair D Kingy and Dmitri Vassilievz  

E-print Network

Torsion waves in metric{aÃ?ne #12;eld theory Alastair D Kingy and Dmitri Vassilievz Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, UK E-mail: yA.D.King@maths.bath.ac.uk E-mail: z

King, Alastair

14

Self-Gravitating Spherically Symmetric Solutions in Scalar-Torsion Theories  

E-print Network

We studied spherically symmetric solutions in scalar-torsion gravity theories in which a scalar field is coupled to torsion with a derivative coupling. We obtained the general field equations from which we extracted a decoupled master equation, the solution of which leads to the specification of all other unknown functions. We first obtained an exact solution which represents a new wormhole-like solution dressed with a regular scalar field. Then, we found large distance linearized spherically symmetric solutions in which the space asymptotically is AdS.

Kofinas, Georgios; Saridakis, Emmanuel N

2015-01-01

15

Importance of torsion and invariant volumes in Palatini theories of gravity  

NASA Astrophysics Data System (ADS)

We study the field equations of extensions of general relativity formulated within a metric-affine formalism setting torsion to zero (Palatini approach). We find that different (second-order) dynamical equations arise depending on whether torsion is set to zero (i) a priori or (ii) a posteriori, i.e., before or after considering variations of the action. Considering a generic family of Ricci-squared theories, we show that in both cases the connection can be decomposed as the sum of a Levi-Cività connection and terms depending on a vector field. However, while in case (i) this vector field is related to the symmetric part of the connection, in (ii) it comes from the torsion part and, therefore, it vanishes once torsion is completely removed. Moreover, the vanishing of this torsion-related vector field immediately implies the vanishing of the antisymmetric part of the Ricci tensor, which therefore plays no role in the dynamics. Related to this, we find that the Levi-Cività part of the connection is due to the existence of an invariant volume associated with an auxiliary metric h??, which is algebraically related with the physical metric g??.

Olmo, Gonzalo J.; Rubiera-Garcia, D.

2013-10-01

16

Torsional oscillations of neutron stars in scalar-tensor theory of gravity  

NASA Astrophysics Data System (ADS)

We study torsional oscillations of neutron stars in the scalar-tensor theory of gravity using the relativistic Cowling approximation. We compute unperturbed neutron star models adopting realistic equations of state for the neutron star's core and crust. For scalar-tensor theories that allow for spontaneous scalarization, the crust thickness can be significantly smaller than in general relativity. We derive the perturbation equation describing torsional oscillations in scalar-tensor theory, and we solve the corresponding eigenvalue problem to find the oscillation frequencies. The fundamental mode (overtone) frequencies become smaller (larger) than in general relativity for scalarized stellar models. Torsional oscillation frequencies may yield information on the crust microphysics if microphysics effects are not degenerate with strong-gravity effects, such as those due to scalarization. To address this issue, we consider two different models for the equation of state of the crust and we look at the effects of electron screening. The effect of scalarization on torsional oscillation frequencies turns out to be smaller than uncertainties in the microphysics for all spontaneous scalarization models allowed by binary pulsar observations. Our study shows that the observation of quasiperiodic oscillations following giant flares can be used to constrain the microphysics of neutron star crusts, whether spontaneous scalarization occurs or not.

Silva, Hector O.; Sotani, Hajime; Berti, Emanuele; Horbatsch, Michael

2014-12-01

17

On Torsion-free Vacuum Solutions of the Model of de Sitter Gauge Theory of Gravity (II)  

E-print Network

It is shown that all torsion-free vacuum solutions of the model of dS gauge theory of gravity are the vacuum solutions of Einstein field equations with the same positive cosmological constant. Furthermore, for the gravitational theories with more general quadratic gravitational Lagrangian ($F^2+T^2$), the torsion-free vacuum solutions are also the vacuum solutions of Einstein field equations.

Chao-Guang Huang; Meng-Sen Ma

2009-06-15

18

Angular momentum and light-front scattering theory  

SciTech Connect

The role of the Leutwyler and Stern spin operator in the angular momentum analysis of light-front scattering theory is analyzed. The equations of formal scattering theory are transformed to the {xi} picture using the unitary operator {ital C}({xi}) recently developed by the author. This operator depends on the two angles which determine the direction of the three-vector part of a lightlike four-vector {xi}. It is shown that an invariant version of light-front perturbation theory developed earlier by the author is related to the standard theory by the unitary operator {ital C}({xi}). It is also shown how to carry out a partial-wave analysis of the Lippmann-Schwinger-like equations obtained by summing a subset of the diagrams of this invariant form of light-front perturbation theory. The analysis presented here makes clear that the {xi} picture overcomes many of the difficulties due to the interaction dependence of light-front angular momentum operators, in particular the difficulties arising from the fact that the individual diagrams of light-front pertubation theory are not rotationally invariant.

Fuda, M.G. (Department of Physics and Astronomy, State University of New York at Buffalo, Buffalo, New York (USA))

1991-09-15

19

Torsion waves in metric-affine field theory  

Microsoft Academic Search

The approach of metric-affine field theory is to define spacetime as a real oriented 4-manifold equipped with a metric and an affine connection. The 10 independent components of the metric tensor and the 64 connection coefficients are the unknowns of the theory. We write the Yang-Mills action for the affine connection and vary it both with respect to the metric

Alastair D. King; Dmitri Vassiliev

2001-01-01

20

de Sitter gauge theory of gravity: an alternative torsion cosmology  

SciTech Connect

A new cosmological model based on the de Sitter gauge theory (dSGT) is studied in this paper. By some transformations, we find, in the dust universe, the cosmological equations of dSGT could form an autonomous system. We conduct dynamics analysis to this system, and find 9 critical points, among which there exist one positive attractor and one negative attractor. The positive attractor shows us that our universe will enter a exponential expansion phase in the end, which is similar to the conclusion of ?CDM. We also carry out some numerical calculations, which confirms the conclusion of dynamics analysis. Finally, we fit the model parameter and initial values to the Union 2 SNIa dataset, present the confidence contour of parameters and obtain the best-fit values of parameters of dSGT.

Ao, Xi-Chen; Li, Xin-Zhou, E-mail: aoxichen@gmail.com, E-mail: kychz@shnu.edu.cn [Shanghai United Center for Astrophysics (SUCA), Shanghai Normal University, 100 Guilin Road, Shanghai 200234 (China)

2011-10-01

21

Torsional barriers of substituted biphenyls calculated using density functional theory: a benchmarking study.  

PubMed

The barriers of torsional isomerization of 13 substituted biphenyls, ranging from 7.4 to 44 kcal mol(-1), were calculated using 9 density functionals (the BP86 and B97D GGAs, the meta-GGA TPSS, hybrids B3LYP, PBE0, ?B97XD, BMK and M06-2X, as well as the double-hybrid B2PLYP), some combined with D and D3 corrections for dispersive interactions, and results were compared with experimental data. As attractive dispersive interactions between substituents had a significant impact on the geometries and stabilities of the ground and transition states of the torsional isomerization pathways, the B3LYP-D, B97-D and TPSS-D3 functionals were identified as the most promising methods, and were used to determine the torsional barriers of 33 other substituted biphenyls with known Gibbs energies of activation (6.0 to 45 kcal mol(-1)). Throughout the 46-member ensemble, results were very accurate relative to experimental values (mean deviation between -0.38 and 0.24 kcal mol(-1)), and narrow distributions of errors were obtained (root-mean-square deviations between 0.14 and 0.16 kcal mol(-1); mean absolute deviations ranging from 0.61 to 0.75 kcal mol(-1)), as long as (1) large triple-? basis sets were used, (2) all conformations were screened at these levels of theory, (3) electronic energies were corrected with zero-point energies and entropic contributions, and (4) solvation effects were taken into account for biphenyl derivatives bearing charged ortho-substituents. With its simple procedures, this study is intended as a benchmark for future determinations of torsional barriers of various biphenyl derivatives. PMID:23493969

Masson, Eric

2013-05-01

22

Analysis of Regular Inflationary Cosmological Models with Two Torsion Functions in POINCARÉ Gauge Theory of Gravity  

NASA Astrophysics Data System (ADS)

Regular inflationary Big Bang scenario with accelerating stage of cosmological expansion at asymptotics proposed earlier in the framework of the Poincaré gauge theory of gravity is investigated. Analysis of regular inflationary cosmological models with two torsion functions filled with scalar field with quadratic potential and ultrarelativistic matter is carried out numerically. Properties of different stages of regular inflationary cosmological solutions are studied, restrictions on admissible values of parameters and initial conditions at a bounce are found. The structure of extremum surface in space of physical variables is investigated.

Garkun, A. S.; Kudin, V. I.; Minkevich, A. V.

23

Spin and orbital angular momentum in gauge theories (I): QED and determination of the angular momentum density  

E-print Network

This two-paper series addresses and fixes the long-standing gauge invariance problem of angular momentum in gauge theories. This QED part reveals: 1) The spin and orbital angular momenta of electrons and photons can all be consistently defined gauge invariantly. 2) These gauge-invariant quantities can be conveniently computed via the canonical, gauge-dependent operators (e.g, $\\psi ^\\dagger \\vec x \\times\\frac 1i \\vec \

X. S. Chen; X. F. Lü; W. M. Sun; F. Wang; T. Goldman

2007-09-23

24

A modified theory of gravity with torsion and its applications to cosmology and particle physics  

E-print Network

In this paper we consider the most general least-order derivative theory of gravity in which not only curvature but also torsion is explicitly present in the Lagrangian, and where all independent fields have their own coupling constant: we will apply this theory to the case of ELKO fields, which is the acronym of the German \\textit{Eigenspinoren des LadungsKonjugationsOperators} designating eigenspinors of the charge conjugation operator, and thus they are a Majorana-like special type of spinors; and to the Dirac fields, the most general type of spinors. We shall see that because torsion has a coupling constant that is still undetermined, the ELKO and Dirac field equations are endowed with self-interactions whose coupling constant is undetermined: we discuss different applications according to the value of the coupling constants and the different properties that consequently follow. We highlight that in this approach, the ELKO and Dirac field's self-interactions depend on the coupling constant as a parameter that may even make these non-linearities manifest at subatomic scales.

Luca Fabbri; Stefano Vignolo

2012-01-26

25

Angular-momentum-dependent orbital-free density functional theory.  

PubMed

Orbital-free (OF) density functional theory (DFT) directly solves for the electron density rather than the wave function of many electron systems, greatly simplifying and enabling large scale first principles simulations. However, the required approximate noninteracting kinetic energy density functionals and local electron-ion pseudopotentials severely restrict the general applicability of conventional OFDFT. Here, we present a new generation of OFDFT called angular-momentum-dependent (AMD)-OFDFT to harness the accuracy of Kohn-Sham DFT and the simplicity of OFDFT. The angular momenta of electrons are explicitly introduced within atom-centered spheres so that the important ionic core region can be accurately described. In addition to conventional OF total energy functionals, we introduce a crucial nonlocal energy term with a set of AMD energies to correct errors due to the kinetic energy density functional and the local pseudopotential. We find that our AMD-OFDFT formalism offers substantial improvements over conventional OFDFT, as we show for various properties of the transition metal titanium. PMID:23971595

Ke, Youqi; Libisch, Florian; Xia, Junchao; Wang, Lin-Wang; Carter, Emily A

2013-08-01

26

Semiclassical complex angular momentum theory and Pade reconstruction for resonances, rainbows, and reaction thresholds  

SciTech Connect

A semiclassical complex angular momentum theory, used to analyze atom-diatom reactive angular distributions, is applied to several well-known potential (one-particle) problems. Examples include resonance scattering, rainbow scattering, and the Eckart threshold model. Pade reconstruction of the corresponding matrix elements from the values at physical (integral) angular momenta and properties of the Pade approximants are discussed in detail.

Sokolovski, D. [School of Mathematics and Physics, Queen's University of Belfast, Belfast, BT7 1NN (United Kingdom); Msezane, A.Z. [Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, Georgia 30314 (United States)

2004-09-01

27

Covariant differential identities and conservation laws in metric-torsion theories of gravitation. II. Manifestly generally covariant theories  

NASA Astrophysics Data System (ADS)

The present paper continues the work of Lompay and Petrov [J. Math. Phys. 54, 062504 (2013)] where manifestly covariant differential identities and conserved quantities in generally covariant metric-torsion theories of gravity of the most general type have been constructed. Here, we study these theories presented more concretely, setting that their Lagrangians {L} are manifestly generally covariant scalars: algebraic functions of contractions of tensor functions and their covariant derivatives. It is assumed that Lagrangians depend on metric tensor g, curvature tensor R, torsion tensor T and its first {{nabla }}{T} and second {{nabla }}{{nabla }}{T} covariant derivatives, besides, on an arbitrary set of other tensor (matter) fields {\\varphi } and their first {{nabla }}{\\varphi } and second {{nabla }}{{nabla }}{\\varphi } covariant derivatives: {L}= {L}({g},{R}; {T},{{nabla }}{T},{{nabla }}{{nabla }}{T}; {\\varphi },{{nabla }}{\\varphi },{{nabla }}{{nabla }}{\\varphi }). Thus, both the standard minimal coupling with the Riemann-Cartan geometry and non-minimal coupling with the curvature and torsion tensors are considered. The studies and results are as follow: (a) A physical interpretation of the Noether and Klein identities is examined. It was found that they are the basis for constructing equations of balance of energy-momentum tensors of various types (canonical, metrical, and Belinfante symmetrized). The equations of balance are presented. (b) Using the generalized equations of balance, new (generalized) manifestly generally covariant expressions for canonical energy-momentum and spin tensors of the matter fields are constructed. In the cases, when the matter Lagrangian contains both the higher derivatives and non-minimal coupling with curvature and torsion, such generalizations are non-trivial. (c) The Belinfante procedure is generalized for an arbitrary Riemann-Cartan space. (d) A more convenient in applications generalized expression for the canonical superpotential is obtained. (e) A total system of equations for the gravitational fields and matter sources are presented in the form more naturally generalizing the Einstein-Cartan equations with matter. This result, being a one of the more important results itself, is to be also a basis for constructing physically sensible conservation laws and their applications.

Lompay, Robert R.; Petrov, Alexander N.

2013-10-01

28

Weakly-Interacting Massive Particles in Torsionally-Gravitating Dirac Theory  

NASA Astrophysics Data System (ADS)

We shall consider the problem of Dark Matter (DM) in torsion gravity with Dirac matter fields; we will consider the fact that if Weakly-Interacting Massive Particles in a bath are allowed to form condensates then torsional effects may be relevant even at galactic scales: we show that torsionally-gravitating Dirac fields have interesting properties for the problem of DM. We discuss consequences.

Fabbri, Luca

2013-08-01

29

Microstructure Evolution and Mechanical Properties of Al-1080 Processed by a Combination of Equal Channel Angular Pressing and High Pressure Torsion  

NASA Astrophysics Data System (ADS)

Equal channel angular pressing (ECAP) and high pressure torsion (HPT) are the most promising severe plastic deformation (SPD) methods. Both methods impose very high strains, leading to extreme work hardening and microstructural refinement. In this paper, billets of Al-1080 were successfully processed by ECAP conducted for up to 10 passes, HPT at an applied pressure of 8 GPa for 5 revolutions, and a combination of ECAP and HPT (ECAP + HPT) at room temperature. The effects of the different SPD processes (ECAP, HPT, and ECAP + HPT) on the evolution of the microstructure and mechanical properties of Al-1080 were investigated. The HPT and ECAP + HPT processes were observed to produce finer grain sizes with greater fractions of high angle grain boundaries (HAGBs) than the ECAP alone. Although the grain sizes after HPT and ECAP + HPT were similar, the ECAP + HPT sample had more dislocations than the HPT sample. HPT after ECAP enhanced the mechanical properties (hardness, tensile strength, and ductility) of the ECAP-processed Al-1080, showing larger dimple size in the tensile fracture surfaces.

El Aal, Mohamed Ibrahim Abd; Yoon, Eun Yoo; Kim, Hyoung Seop

2013-06-01

30

Parallel spinors and connections with skew-symmetric torsion in string theory  

Microsoft Academic Search

We describe all almost contact metric, almost hermitian and $G_2$-structures admitting a connection with totally skew-symmetric torsion tensor, and prove that there exists at most one such connection. We investigate its torsion form, its Ricci tensor, the Dirac operator and the $\\\

Thomas Friedrich; Stefan Ivanov

2001-01-01

31

Theory of pure rotational transitions in doubly degenerate torsional states of ethane  

NASA Technical Reports Server (NTRS)

It is shown that pure rotational transitions in doubly degenerate torsional states of C2H6 (with selection rules Delta K = 0, plus or minus 1) are made allowed by Coriolis interaction between torsion and dipole-allowed vibrations. Expressions are presented for integrated intensities from which strengths of lines in the millimeter region can be calculated.

Rosenberg, A.; Susskind, J.

1979-01-01

32

Magnetometer Bias Calibration Based on Relative Angular Position: Theory and Experimental Comparative Evaluation  

E-print Network

Magnetometer Bias Calibration Based on Relative Angular Position: Theory and Experimental for esti- mating the sensor bias of three-axis magnetometers (or any other field sensor). Our approach employs relative angular position measurements to estimate the three-axis magnetometer measurement bias

Eustice, Ryan

33

Spin and Orbital angular momentum propagation in anisotropic media: theory  

E-print Network

This paper is devoted to study the propagation of light beams carrying orbital angular momentum in optically anisotropic media. We first review some properties of homogeneous anisotropic media, and describe how the paraxial formalism is modified in order to proceed with a new approach dealing with a general setting of paraxial propagation along uniaxial inhomogeneous media. This approach is suitable for describing the space-variant-optical-axis phase plates.

Antonio Picón; Albert Benseny; Jordi Mompart; Gabriel F. Calvo

2011-05-27

34

Interacting spin 0 fields with torsion via Duffin-Kemmer-Petiau theory  

E-print Network

Here we study the behaviour of spin 0 sector of DKP field in spaces with torsion. First we show that in a Riemann-Cartan manifold DKP field presents an interaction with torsion when minimal coupling is performed, contrary to the behaviour of KG field, a result that breaks the usual equivalence between DKP and KG fields. Next we analyse the case of Teleparallel Equivalent of General Relativity (Weitzenb\\"ock manifold), showing that in this case there is a perfect agreement between KG and DKP fields. The origins of both results are also discussed.

Lunardi, J T; Teixeira, R G

2001-01-01

35

Torsion in superstrings  

SciTech Connect

String theories on a background manifold with torsion are discussed. Candidate vacuum configurations are discussed for ten-dimensional superstrings. These are compactified on M/sub 4/ x K, where M/sub 4/ is four-dimensional and K is some compact six-dimensional manifold. Solutions with non-zero torsion on K are emphasized. The compactification problem is approached both from the effective field theory point of view and directly using string considerations. The construction of string theories in curved space with torsion is then discussed. Particular emphasis is put on the constraints on space-time supersymmetry in the Green-Schwarz approach. Two-dimensional non-linear sigma models are used to describe the propagation of strings in background geometries with torsion. (LEW)

Bars, I.; Nemeschansky, D.; Yankielowicz, S.

1985-09-01

36

Theory of angular dispersive imaging hard x-ray spectrographs  

E-print Network

A spectrograph is an optical instrument that disperses photons of different energies into distinct directions and space locations, and images photon spectra on a position-sensitive detector. Spectrographs consist of collimating, angular dispersive, and focusing optical elements. Bragg reflecting crystals arranged in an asymmetric scattering geometry are used as the dispersing elements. A ray-transfer matrix technique is applied to propagate x-rays through the optical elements. Several optical designs of hard x-ray spectrographs are proposed and their performance is analyzed. Spectrographs with an energy resolution of 0.1 meV and a spectral window of imaging up to a few tens of meVs are shown to be feasible for inelastic x-ray scattering (IXS) spectroscopy applications. In another example, a spectrograph with a 1-meV spectral resolution and 85-meV spectral window of imaging is considered for Cu K-edge resonant IXS (RIXS).

Shvyd'ko, Yuri

2015-01-01

37

ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS  

SciTech Connect

The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification of three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.

Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M., E-mail: rrr@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08540 (United States)

2013-06-10

38

Torsion and conservation laws  

Microsoft Academic Search

The interaction of spinor and electromagnetic fields with the torsion of space-time is studied within the framework of the Einstein-Cartan theory. The equivalent nonlinear theory in Riemann space is obtained. The conservation laws for the vector and pseudovector currents are investigated in the nonlinear theory.

E. V. Smetanin; E. Ostgaard; V. Canute; L. D. Landau; R. L. Bowers; E. P. T. Liang; H. Heintzmann; W. Hillebrandt; V. Ureche; S. Weinberg; B. Zel; I. M. Lifshits

1986-01-01

39

Mirage Torsion  

E-print Network

Z_NxZ_M orbifold models admit the introduction of a discrete torsion phase. We find that models with discrete torsion have an alternative description in terms of torsionless models. More specifically, discrete torsion can be 'gauged away' by changing the shifts by lattice vectors. Similarly, a large class of the so-called generalized discrete torsion phases can be traded for changing the background fields (Wilson lines) by lattice vectors. We further observe that certain models with generalized discrete torsion are equivalent to torsionless models with the same gauge embedding but based on different compactification lattices. We also present a method of classifying heterotic Z_NxZ_M orbifolds.

Plöger, F; Ratz, M; Vaudrevange, P K S; Ploger, Felix; Ramos-Sanchez, Saul; Ratz, Michael; Vaudrevange, Patrick K.S.

2007-01-01

40

Mirage Torsion  

E-print Network

Z_NxZ_M orbifold models admit the introduction of a discrete torsion phase. We find that models with discrete torsion have an alternative description in terms of torsionless models. More specifically, discrete torsion can be 'gauged away' by changing the shifts by lattice vectors. Similarly, a large class of the so-called generalized discrete torsion phases can be traded for changing the background fields (Wilson lines) by lattice vectors. We further observe that certain models with generalized discrete torsion are equivalent to torsionless models with the same gauge embedding but based on different compactification lattices. We also present a method of classifying heterotic Z_NxZ_M orbifolds.

Felix Ploger; Saul Ramos-Sanchez; Michael Ratz; Patrick K. S. Vaudrevange

2007-02-21

41

Second order classical perturbation theory for atom surface scattering: Analysis of asymmetry in the angular distribution  

NASA Astrophysics Data System (ADS)

A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to "soft" corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.

Zhou, Yun; Pollak, Eli; Miret-Artés, Salvador

2014-01-01

42

Second order classical perturbation theory for atom surface scattering: Analysis of asymmetry in the angular distribution  

SciTech Connect

A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to “soft” corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.

Zhou, Yun, E-mail: zhou.yun.x@gmail.com; Pollak, Eli, E-mail: eli.pollak@weizmann.ac.il [Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot (Israel)] [Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot (Israel); Miret-Artés, Salvador, E-mail: s.miret@iff.csic.es [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)] [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)

2014-01-14

43

Numerical calculation of near field scalar diffraction using angular spectrum of plane waves theory and FFT  

Microsoft Academic Search

t is a known fact that near field diffraction or Fresnel diffraction calculations are difficult to perform exactly. It is in general necessary to make some approximations in order to obtain a more suitable form. In this work, a numerical implementation based on angular spectrum theory for near field diffraction is presented. The method uses Fast Fourier Transforms (FFT) and

Adrian Carbajal-Dominguez; J. Bernal; Jesus E. Gomez Correa; Gabriel Martinez Niconoff

2010-01-01

44

Dangerous angular Kaluza-Klein/glueball relics in string theory cosmology  

NASA Astrophysics Data System (ADS)

The presence of Kaluza-Klein (KK) particles in the universe is a potential manifestation of string theory cosmology. In general, they can be present in the high temperature bath of the early universe. In particular examples, string theory inflation often ends with brane-antibrane annihilation followed by the energy cascading through massive closed string loops to KK modes which then decay into lighter standard model particles. However, massive KK modes in the early universe may become dangerous cosmological relics if the inner manifold contains warped throat(s) with approximate isometries. In the complimentary picture, in the AdS/CFT dual gauge theory with extra isometries, massive glueballs of various spins become the dangerous cosmological relics. The decay of these angular KK modes/glueballs, located around the tip of the throat, is caused by isometry breaking which results from gluing the throat to the compact Calabi-Yau (CY) manifold. We address the problem of these angular KK particles/glueballs, studying their interactions and decay channels, from the theory side, and the resulting cosmological constraints on the warped compactification parameters, from the phenomenology side. The abundance and decay time of the long-lived nonrelativistic angular KK modes depend strongly on the parameters of the warped geometry, so that observational constraints rule out a significant fraction of the parameter space. In particular, the coupling of the angular KK particles can be weaker than gravitational.

Dufaux, J. F.; Kofman, L.; Peloso, M.

2008-07-01

45

Spin and orbital angular momentum in gauge theories: Nucleon spin structure and multipole radiation revisited  

E-print Network

We address and solve the long-standing gauge-invariance problem of the nucleon spin structure. Explicitly gauge-invariant spin and orbital angular momentum operators of quarks and gluons are obtained. This was previously thought to be an impossible task, and opens a more promising avenue towards the understanding of the nucleon spin. Our research also justifies the traditional use of the canonical, gauge-dependent angular momentum operators of photons and electrons in the multipole-radiation analysis and labeling of atomic states; and sheds much light on the related energy-momentum problem in gauge theories, especially in connection with the nucleon momentum.

Xiang-Song Chen; Xiao-Fu Lü; Wei-Min Sun; Fan Wang; T. Goldman

2008-06-19

46

Spin-torsion coupling and gravitational moments of Dirac fermions: Theory and experimental bounds  

NASA Astrophysics Data System (ADS)

We discuss the quantum dynamics of a Dirac fermion particle in the Poincaré gauge gravitational field. The minimal as well as the Pauli-type nonminimal coupling of a fermion with external fields is studied, bringing into consideration the notions of the translational and the Lorentz gravitational moments. The anomalous gravitomagnetic and gravitoelectric moments are ruled out on the basis of the covariance arguments. We derive the general Foldy-Wouthuysen transformation for an arbitrary configuration of the Poincaré gauge gravitational field without assuming it is weak. Making use of the Foldy-Wouthuysen Hamiltonian for the Dirac particle coupled to a magnetic field in a noninertial reference system, we analyze the recent experimental data and obtain bounds on the spacetime torsion.

Obukhov, Yuri N.; Silenko, Alexander J.; Teryaev, Oleg V.

2014-12-01

47

Numerical calculation of near field scalar diffraction using angular spectrum of plane waves theory and FFT  

Microsoft Academic Search

t is a known fact that near field diffraction or Fresnel diffraction\\u000acalculations are difficult to perform exactly. It is in general necessary to\\u000amake some approximations in order to obtain a more suitable form. In this work,\\u000aa numerical implementation based on angular spectrum theory for near field\\u000adiffraction is presented. The method uses Fast Fourier Transforms (FFT) and

Adrian Carbajal-Dominguez; J. Bernal; Jesus E. Gomez Correa; Gabriel Martinez Niconoff

2010-01-01

48

Comment on "Spin and Orbital Angular Momentum in Gauge Theories" by X. S. Chen et. al. (PRL100, 232002 (2008))  

E-print Network

The individual parts of the total angular momentum operator in interacting theories cannot satisfy the canonical angular momentum commutation rule, including those proposed in the above paper. Furthermore, the operators in the new proposal a) are non-local in general gauge, b) do not have proper Lorentz transformation properties, and c) do not have any known physical measurements.

Xiangdong Ji

2008-10-27

49

Torsional viscometer  

NSDL National Science Digital Library

Solve the cylindrical Navier-Stokes equations for polymer flow in a torsional viscometer; calculate polymer viscosity from torque; qualitatively evaluate non-Newtonian nature of flow from a second torque data point.

Powell, Adam C., IV

2003-11-14

50

Torsional deformity.  

PubMed

Torsional deformity should be localized, quantitated, and usually managed by "observation," an approach that is set forth in detail in this article. Shoe modifications and daytime braces are inappropriate. Night splints or operative procedures are rarely indicated. PMID:3786004

Staheli, L T

1986-12-01

51

Symmetry broken and restored coupled-cluster theory: I. Rotational symmetry and angular momentum  

NASA Astrophysics Data System (ADS)

We extend coupled-cluster (CC) theory performed on top of a Slater determinant breaking rotational symmetry to allow for the exact restoration of the angular momentum at any truncation order. The main objective relates to the description of near-degenerate finite quantum systems with an open-shell character. As such, the newly developed many-body formalism offers a wealth of potential applications and further extensions dedicated to the ab initio description of, e.g., doubly open-shell atomic nuclei and molecule dissociation. The formalism, which encompasses both single-reference CC theory and projected Hartree–Fock theory as particular cases, permits the computation of usual sets of connected diagrams while consistently incorporating static correlations through the highly non-perturbative restoration of rotational symmetry. Interestingly, the yrast spectroscopy of the system, i.e. the lowest energy associated with each angular momentum, is accessed within a single calculation. A key difficulty presently overcome relates to the necessity to handle generalized energy and norm kernels for which naturally terminating CC expansions could be eventually obtained. The present work focuses on SU(2) but can be extended to any (locally) compact Lie group and to discrete groups, such as most point groups. In particular, the formalism will be soon generalized to U(1) symmetry associated with particle number conservation. This is relevant to Bogoliubov CC theory that was recently applied to singly open-shell nuclei.

Duguet, T.

2015-02-01

52

Theory for noise of propellers in angular inflow with parametric studies and experimental verification  

NASA Technical Reports Server (NTRS)

This report presents the derivation of a frequency domain theory and working equations for radiation of propeller harmonic noise in the presence of angular inflow. In applying the acoustic analogy, integration over the tangential coordinate of the source region is performed numerically, permitting the equations to be solved without approximation for any degree of angular inflow. Inflow angle is specified in terms of yaw, pitch, and roll angles of the aircraft. Since these can be arbitrarily large, the analysis applies with equal accuracy to propellers and helicopter rotors. For thickness and loading, the derivation is given in complete detail with working equations for near and far field. However, the quadrupole derivation has been carried only far enough to show feasibility of the numerical approach. Explicit formulas are presented for computation of source elements, evaluation of Green's functions, and location of observer points in various visual and retarded coordinate systems. The resulting computer program, called WOBBLE has been written in FORTRAN and follows the notation of this report very closely. The new theory is explored to establish the effects of varying inflow angle on axial and circumferential directivity. Also, parametric studies were performed to evaluate various phenomena outside the capabilities of earlier theories, such as an unsteady thickness effect. Validity of the theory was established by comparison with test data from conventional propellers and Prop Fans in flight and in wind tunnels under a variety of operating conditions and inflow angles.

Hanson, Donald B.; Parzych, David J.

1993-01-01

53

Symmetry broken and restored coupled-cluster theory I. Rotational symmetry and angular momentum  

E-print Network

We extend coupled-cluster theory performed on top of a Slater determinant breaking rotational symmetry to allow for the exact restoration of the angular momentum at any truncation order. The main objective relates to the description of near-degenerate finite quantum systems with an open-shell character. As such, the newly developed many-body formalism offers a wealth of potential applications and further extensions dedicated to the ab initio description of, e.g., doubly open-shell atomic nuclei and molecule dissociation. The formalism, which encompasses both single-reference coupled cluster theory and projected Hartree-Fock theory as particular cases, permits the computation of usual sets of connected diagrams while consistently incorporating static correlations through the highly non-perturbative restoration of rotational symmetry. Interestingly, the yrast spectroscopy of the system, i.e. the lowest energy associated with each angular momentum, is accessed within a single calculation. A key difficulty presently overcome relates to the necessity to handle generalized energy {\\it and} norm kernels for which naturally terminating coupled-cluster expansions could be eventually obtained. The present work focuses on $SU(2)$ but can be extended to any (locally) compact Lie group and to discrete groups, such as most point groups. In particular, the formalism will be soon generalized to $U(1)$ symmetry associated with particle number conservation. This is relevant to Bogoliubov coupled cluster theory that was recently formulated and applied to singly open-shell nuclei.

T. Duguet

2014-11-03

54

Degenerate Perturbation Theory Describing the Mixing of Orbital Angular Momentum Modes in Fabry-Perot Cavity Resonators  

E-print Network

Degenerate Perturbation Theory Describing the Mixing of Orbital Angular Momentum Modes in Fabry spin-orbit coupling [5, 6]. In this Rapid Communication, we extend electromagnetic resonator theory [11: December 28, 2008) Abstract We present an analytic perturbation theory which extends the paraxial

Nöckelm, Jens

55

Angular momentum dependent orbital-free density functional theory: Formulation and implementation  

NASA Astrophysics Data System (ADS)

Orbital-free density functional theory (OFDFT) directly solves for the ground-state electron density. It scales linearly with respect to system size, providing a promising tool for large-scale material simulations. Removal of the orbitals requires use of approximate noninteracting kinetic energy density functionals. If replacing ionic cores with pseudopotentials, removal of the orbitals also requires these pseudopotentials to be local. These are two severe challenges to the capabilities of conventional OFDFT. While main group elements are often well described within conventional OFDFT, transition metals remain intractable due to their localized d electrons. To advance the accuracy and general applicability of OFDFT, we have recently reported a general angular momentum dependent formulation as a next-generation OFDFT. In this formalism, we incorporate the angular momenta of electrons by devising a hybrid scheme based on a muffin tin geometry: inside spheres centered at the ionic cores, the electron density is expanded in a set of atom-centered basis functions combined with an onsite density matrix. The explicit treatment of the angular momenta of electrons provides an important basis for accurately describing the important ionic core region, which is not possible in conventional OFDFT. In addition to the conventional OFDFT total energy functional, we introduce a nonlocal energy term containing a set of angular momentum dependent energies to correct the errors due to the approximate kinetic energy density functional and local pseudopotentials. Our approach greatly increases the accuracy of OFDFT while largely preserving its numerical simplicity. Here, we provide details of the theoretical formulation and practical implementation, including the hybrid scheme, the derivation of the nonlocal energy term, the choice of basis functions, the direct minimization of the total energy, the procedure to determine the angular momentum dependent energies, the force formula with Pulay correction, and the solution to emerging numerical instability. To test the angular momentum dependent OFDFT formalism and its numerical implementations, we calculate a diverse set of properties of the transition metal Ti and compare with different levels of DFT approximation. The results suggest that angular momentum dependent OFDFT ultimately will extend the reliable reach of OFDFT to the rest of the periodic table.

Ke, Youqi; Libisch, Florian; Xia, Junchao; Carter, Emily A.

2014-04-01

56

Nonlinear Hysteretic Torsional Waves  

E-print Network

We theoretically study and experimentally report the propagation of nonlinear hysteretic torsional pulses in a vertical granular chain made of cm-scale, self-hanged magnetic beads. As predicted by contact mechanics, the torsional coupling between two beads is found nonlinear hysteretic. This results in a nonlinear pulse distortion essentially different from the distortion predicted by classical nonlinearities, and in a complex dynamic response depending on the history of the wave particle angular velocity. Both are consistent with the predictions of purely hysteretic nonlinear elasticity and the Preisach-Mayergoyz hysteresis model, providing the opportunity to study the phenomenon of nonlinear dynamic hysteresis in the absence of other type of material nonlinearities. The proposed configuration reveals a plethora of interesting phenomena including giant amplitude-dependent attenuation, short term memory as well as dispersive properties. Thus, it could find interesting applications in nonlinear wave control de...

Cabaret, J; Theocharis, G; Andreev, V; Gusev, V E; Tournat, V

2015-01-01

57

Quaternions, Torsion and the Physical Vacuum: Theories of M. Sachs and G. Shipov Compared  

NASA Astrophysics Data System (ADS)

Of several developments of unified field theories in the spirit of Einstein's original objective of a fully geometric description of all classical fields as well as quantum mechanics, two are particularly noteworthy. The works of Mendel Sachs and Gennady Shipov stand apart as major life works comprising tens of papers, several monographs and decades of effort. Direct comparison of these theories is hampered however by differences in notation and conceptual view-point. Despite these differences, there are many parallels between the fundamental mathematical structures appearing in each. In this paper we discuss the main tenets of the two approaches and demonstrate that they both give rise to a factorization of the invariant interval of general relativity.

Cyganski, David; Page, William S.

58

Testicular torsion  

MedlinePLUS

Torsion of the testis; Testicular ischemia; Testicular twisting ... exercise. In some cases, there is no clear cause. The condition is more common during the first year of life and at the beginning of adolescence (puberty). However, it may happen in older men.

59

Torsional locomotion  

PubMed Central

One edge of an elastic rod is inserted into a friction-less and fitting socket head, whereas the other edge is subjected to a torque, generating a uniform twisting moment. It is theoretically shown and experimentally proved that, although perfectly smooth, the constraint realizes an expulsive axial force on the elastic rod, which amount is independent of the shape of the socket head. The axial force explains why screwdrivers at high torque have the tendency to disengage from screw heads and demonstrates torsional locomotion along a perfectly smooth channel. This new type of locomotion finds direct evidence in the realization of a ‘torsional gun’, capable of transforming torque into propulsive force. PMID:25383038

Bigoni, D.; Dal Corso, F.; Misseroni, D.; Bosi, F.

2014-01-01

60

Analysis of long torsional strings by proper orthogonal decomposition  

Microsoft Academic Search

Nonlinear excitations cause angular vibrations in torsional strings. In long strings, the vibrations are characterized by different dynamic behavior over the length. For a general case of a long torsional string, a simplified mathematical model is introduced and numerically simulated. In order to gain insight into the complex spatio-temporal dynamics, the method of proper orthogonal decomposition is applied. A short

E. Kreuzer; O. Kust

1996-01-01

61

Bellows joint absorbs torsional deflections in duct system  

NASA Technical Reports Server (NTRS)

Long, thin-walled bellows compressed into a short length absorbs the same amount of torsional deflection as the same tube in full length condition and saves in cost, complexity and space. This bellows has lower torsional spring rate to absorb the bulk of the duct assembly tortional deflections, leaving the other bellows free to absorb axial and angular deflections.

Daniels, C. M.

1966-01-01

62

Discrete torsion, de Sitter tunneling vacua and AdS brane: U(1) gauge theory on D 4-brane and an effective curvature  

NASA Astrophysics Data System (ADS)

The U(1) gauge dynamics on a D 4-brane is revisited, with a two form, to construct an effective curvature theory in a second order formalism. We exploit the local degrees in a two form, and modify its dynamics in a gauge invariant way, to incorporate a non-perturbative metric fluctuation in an effective D 4-brane. Interestingly, the near horizon D 4-brane is shown to describe an asymptotic Anti de Sitter (AdS) in a semi-classical regime. Using Weyl scaling(s), we obtain the emergent rotating geometries leading to primordial de Sitter (dS) and AdS vacua in a quantum regime. Under a discrete transformation, we re-arrange the mixed dS patches to describe a Schwazschild-like dS (SdS) and a topological-like dS (TdS) black holes. We analyze SdS vacuum for Hawking radiations to arrive at Nariai geometry, where a discrete torsion forms a condensate. We perform thermal analysis to identify Nariai vacuum with a TdS. Investigation reveals an AdS patch within a thermal dS brane, which may provide a clue to unfold dS/CFT. In addition, the role of dark energy, sourced by a discrete torsion, in the dS vacua is investigated using Painleve geometries. It is argued that a D-instanton pair is created by a discrete torsion, with a Big Bang/Crunch, at the past horizon in a pure dS. Nucleation, of brane/anti-brane pair(s), is qualitatively analyzed to construct an effective space-time on a D 4-brane and its anti brane. Analysis re-assures the significant role played by a non-zero mode, of NS-NS two form, to generalize the notion of branes within a brane.

Singh, Abhishek K.; Pandey, K. Priyabrat; Singh, Sunita; Kar, Supriya

2013-05-01

63

Spin and orbital angular momentum in gauge theories (II): QCD and nucleon spin structure  

E-print Network

Parallel to the construction of gauge invariant spin and orbital angular momentum for QED in paper (I) of this series, we present here an analogous but non-trivial solution for QCD. Explicitly gauge invariant spin and orbital angular momentum operators of quarks and gluons are obtained. This was previously thought to be an impossible task, and opens a more promising avenue towards the understanding of the nucleon spin structure.

X. S. Chen; X. F. Lü; W. M. Sun; F. Wang; T. Goldman

2007-09-09

64

Angular Acceleration  

NSDL National Science Digital Library

The simulation of a rotating wheel below shows the relationship between angular position, angular velocity, and angular acceleration. Graphs of angular position and angular velocity as a function of time are shown.

Christian, Wolfgang; Belloni, Mario

2008-02-19

65

Derivation of Einstein-Cartan theory from general relativity  

E-print Network

General relativity cannot describe exchange of intrinsic and orbital angular momentum. Einstein Cartan theory, which includes affine torsion, resolves this problem. All early approaches to Einstein Cartan theory treated inclusion of torsion as an independent assuption. In 1986 the author published a derivation of Einstein Cartan theory from general relativity with classical spin, with no additional assumptions or parameters. This paper adds simpler explanations, correction of a factor of 2, more computational details, a discussion of relevance to cosmic inflation, a summary of the evidence in support of Einstein Cartan theory, and a discussion of limitations of the derivation.

R. J. Petti

2014-12-03

66

Excited bands of [sup 168]Yb in an angular momentum projected theory  

SciTech Connect

The angular momentum projected Tamm-Dancoff approximation is applied to describe eight excited rotational bands of the nucleus [sup 168]Yb up to very high angular momenta. The good agreement with the experimental data allows us to assign parity and angular momentum to some bands which previously had uncertain assignment. Beside the energy levels, we describe moments of inertia, gyromagnetic factors, and [ital B]([ital E]2) transition probabilities along the yrast band. The pairing properties of this nucleus at high spins are discussed in the frame of a symmetry violating wave function. We do not find it necessary to invoke a phase transition to obtain a good agreement with the experimental data at very high spins.

Sun, Y.; Egido, J.L. (Departamento de Fisica Teorica C-XI, Universidad Autonoma de Madrid, E-28049 Madrid (Spain))

1994-10-01

67

Variable stiffness torsion springs  

NASA Technical Reports Server (NTRS)

In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

Alhorn, Dean C. (inventor); Polites, Michael E. (inventor)

1994-01-01

68

Variable stiffness torsion springs  

NASA Technical Reports Server (NTRS)

In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

Alhorn, Dean C. (inventor); Polites, Michael E. (inventor)

1995-01-01

69

Transverse coincidence-structures in spontaneous parametric down-conversion with orbital angular momentum: Theory  

E-print Network

Coincidence-structures in the transverse plane of Type-II spontaneous parametric down-conversion carrying orbital angular momentum are obtained. Azimuthal symmetry breaking around the pump beam direction reveals itself on these quantum images. Analytical expressions for the amplitude probability of the down conversion process are shown including the nonlinear polarizability components.

Geraldo A. Barbosa

2007-06-06

70

Noncontact measurement of angular deflection  

NASA Technical Reports Server (NTRS)

Technique for measuring instantaneous angular deflection of object requires no physical contact. Technique utilizes two flat refractors, converging lens, and different photocell. Distinction of method is its combination of optical and electromechanical components into feedback system in which measurement error is made to approach zero. Application is foreseen in measurement of torsional strain.

Bryant, E. L.

1978-01-01

71

Hall viscosity, spin density, and torsion  

E-print Network

We investigate the relationship between Hall viscosity, spin density and response to geometric torsion. For the most general effective action for relativistic gapped systems, the presence of non-universal terms implies that there is no relationship between torsion response and Hall viscosity. We also consider free relativistic and non-relativistic microscopic actions and again verify the existence of analogous non-universal couplings. Explicit examples demonstrate that torsion response is unrelated to both Hall viscosity and spin density. We also argue that relativistic gapped theories must have vanishing Hall viscosity in Lorentz invariant vacuums.

Michael Geracie; Siavash Golkar; Matthew M. Roberts

2014-10-09

72

Torsion and entropy driven denaturation of DNA  

NASA Astrophysics Data System (ADS)

A unified theory of the denaturation transition having torsion energy as the control parameter has been formulated here in the framework of the mapping of a DNA molecule onto a Heisenberg spin system. The torsion energy incorporates the torque, tension and temperature, the latter being associated with the twist angle. The denaturation transition can be mapped onto the quantum phase transition induced by a quench when the temperature effect is incorporated in the quench time and torsion takes the role of the external field. The denaturation transition occurs when the entanglement entropy of the spin system vanishes.

Roy, Subhamoy Singha; Bandyopadhyay, Pratul

2013-11-01

73

Torsional Stability of Aluminum Alloy Seamless Tubing  

NASA Technical Reports Server (NTRS)

Torsion tests were made on 51ST aluminum-alloy seamless tubes having diameter-to-thickness ratios of from 77 to 139 and length-to-diameter ratios of from 1 to 60. The torsional strengths developed in the tubes which failed elastically (all tubes having lengths greater than 2 to 6 times the diameter) were in most cases within 10 percent of the value indicated by the theories of Donnel, Timoshenko, and Sturm, assuming a condition of simply supported ends.

Moore, R L; Paul, D A

1939-01-01

74

Gravitation Is Torsion  

E-print Network

The mantra about gravitation as curvature is a misnomer. The curvature tensor for a standard of rest does not describe acceleration in a gravitational field but the \\underline{gradient} of the acceleration (e.g. geodesic deviation). The gravitational field itself (Einstein 1907) is essentially an accelerated reference system. It is characterized by a field of orthonormal four-legs in a Riemann space with Lorentz metric. By viewing vectors at different events having identical leg-components as parallel (teleparallelism) the geometry in a gravitational field defines torsion. This formulation of Einstein's 1907 principle of equivalence uses the same Riemannian metric and the same 1916 field equations for his theory of gravitation and fulfills his vision of General Relativity.

Engelbert L. Schucking

2008-03-28

75

Dynamical torsion in view of a distinguished class of Dirac operators  

E-print Network

In this paper we discuss geometric torsion in terms of a distinguished class of Dirac operators. We demonstrate that from this class of Dirac operators a variational problem for torsion can be derived similar to that of Yang-Mills gauge theory. As a consequence, one ends up with propagating torsion even in vacuum as opposed to Einstein-Cartan theory.

Tolksdorf Juergen

2014-07-14

76

Multimodality imaging in adnexal torsion.  

PubMed

Adnexal torsions are one among the causes of acute pelvic pain in females. Commonly occurring adnexal torsions are ovarian either involving the normal ovary with functional cysts or an associated mass. Fallopian tube torsions, torsions involving paraovarian, fimbrial cysts and subserosal fibroids are rare. Here we discuss the multimodality imaging approach for the diagnosis of adnexal torsion, its limitations and mimics. PMID:25528961

Patil, Aruna R; Nandikoor, Shrivalli; Rao, Anuradha; M Janardan, Govindarajan; Kheda, AmithaVikrama; Hari, Mahesh; Basappa, Sharana

2015-02-01

77

Torsion cosmology and the accelerating universe  

SciTech Connect

Investigations of the dynamic modes of the Poincare gauge theory of gravity found only two good propagating torsion modes; they are effectively a scalar and a pseudoscalar. Cosmology affords a natural situation where one might see observational effects of these modes. Here, we consider only the 'scalar torsion' mode. This mode has certain distinctive and interesting qualities. In particular, this type of torsion does not interact directly with any known matter, and it allows a critical nonzero value for the affine scalar curvature. Via numerical evolution of the coupled nonlinear equations we show that this mode can contribute an oscillating aspect to the expansion rate of the Universe. From the examination of specific cases of the parameters and initial conditions we show that for suitable ranges of the parameters the dynamic 'scalar torsion' model can display features similar to those of the presently observed accelerating universe.

Shie, K.-F. [Department of Physics, National Central University, Chungli 320, Taiwan (China); Nester, James M. [Department of Physics, National Central University, Chungli 320, Taiwan (China); Graduate Institute of Astronomy, National Central University, Chungli 320, Taiwan (China); Center for Mathematics and Theoretical Physics, National Central University, Chungli 320, Taiwan (China); Yo, H.-J. [Department of Physics, National Cheng-Kung University, Tainan 701, Taiwan (China)

2008-07-15

78

Role of angular momentum conservation in unimolecular translational energy release: Validity of the orbiting transition state theory  

NASA Astrophysics Data System (ADS)

The translational kinetic energy release distribution (KERD) for the halogen loss reaction of the bromobenzene and iodobenzene cations has been reinvestigated on the microsecond time scale. Two necessary conditions of validity of the orbiting transition state theory (OTST) for the calculation of kinetic energy release distributions (KERDs) have been formulated. One of them examines the central ion-induced dipole potential approximation. As a second criterion, an adiabatic parameter is derived. The lower the released translational energy and the total angular momentum, the larger the reduced mass, the rotational constant of the molecular fragment, and the polarizability of the released atom, the more valid is the OTST. Only the low-energy dissociation of the iodobenzene ion (E ?0.45eV, where E is the internal energy above the reaction threshold) is found to fulfill the criteria of validity of the OTST. The constraints that act on the dissociation dynamics have been studied by the maximum entropy method. Calculations of entropy deficiencies (which measure the deviation from a microcanonical distribution) show that the pair of fragments does not sample the whole of the phase space that is compatible with the mere specification of the internal energy. The major constraint that results from conservation of angular momentum is related to a reduction of the dimensionality of the dynamics of the translational motion to a two-dimensional space. A second and minor constraint that affects the KERD leads to a suppression of small translational releases, i.e., accounts for threshold behavior. At high internal energies, the effects of curvature of the reaction path and of angular momentum conservation are intricately intermeddled and it is not possible to specify the share of each effect.

Gridelet, E.; Lorquet, J. C.; Leyh, B.

2005-03-01

79

Quantum simulations of gauge theories with ultracold atoms: local gauge invariance from angular momentum conservation  

E-print Network

Quantum simulations of High Energy Physics, and especially of gauge theories, is an emerging and exciting direction in quantum simulations. However, simulations of such theories, compared to simulations of condensed matter physics, must satisfy extra restrictions, such as local gauge and Lorentz invariance. In this paper we discuss these special requirements, and present a new method for quantum simulation of lattice gauge theories using ultracold atoms. This method allows to include local gauge invariance as a fundamental symmetry of the atomic Hamiltonian, arising from natural atomic interactions and conservation laws (and not as a property of a low energy sector). This allows us to implement elementary gauge invariant interactions for three lattice gauge theories: compact QED (U(1)), SU(N) and Z_N, which can be used to build quantum simulators in 1+1 dimensions. We also present a new loop method, which uses the elementary interactions as building blocks in the effective construction of quantum simulations for d+1 dimensional lattice gauge theories (d>1), without having to use Gauss's law as a constraint, as in previous proposals. We discuss in detail the quantum simulation of 2+1 dimensional compact QED and provide a numerical proof of principle. The simplicity of the already gauge invariant elementary interactions of this model suggests it may be useful for future experimental realizations.

Erez Zohar; J. Ignacio Cirac; Benni Reznik

2013-08-28

80

Torsion of the gallbladder.  

PubMed

Two patients are presented with torsion of the gallbladder, a rare disorder mainly seen in elderly women. The postoperative course was uneventful in both patients. The anatomic abnormalities which allow torsion of the gallbladder are discussed together with some etiological factors. The prognosis of this disorder is favorable when cholecystectomy is performed without delay. PMID:3374823

de Weerd, G J; Frima, A J

1988-04-01

81

Angular zeros of Brown, Mikaelian, Sahdev, and Samuel and the factorization of tree amplitudes in gauge theories  

NASA Astrophysics Data System (ADS)

The zero in the angular distribution of the process qq¯-->?W (discovered by Brown, Mikaelian, Sahdev, and Samuel) when the magnetic moment of the W has the Yang-Mills value, is shown to be a consequence of a factorizability of the amplitude into one factor which contains the dependence on the charge or other internal-symmetry indices, and another which contains the dependence on the spin or polarization indices. In gauge theories generally, this factorization is found to hold for any four-particle tree-approximation amplitude, when one or more of the four particles is a gauge-field quantum. The factorization hinges on a "spatial generalized Jacobi identity" obeyed by the polarization-dependent factors of the vertices, in analogy to the generalized Jacobi identity obeyed by the charge-index-dependent factors. We emphasize that observation of the process qq¯-->?W in pp¯ collisions or the decay W-->qq¯? provides a direct test of the prediction of gauge (Yang-Mills) theories for vector-vector-vector couplings, just as much as would e+e--->Z-->W+W-.

Goebel, C. J.; Halzen, F.; Leveille, J. P.

1981-06-01

82

[Tibial torsion deformities].  

PubMed

Tibial torsion defects are usually not clinically evident and, hence, are often overlooked. Clinical examination and CT scan have proved to be the best ways of measuring static tibial torsion, whereas dynamic measurements are usually performed in the clinic and the "gait laboratory." Only few studies have determined there to be a connection between a torsion defect in the lower leg and expected pathological conditions of the knee and ankle joints. However, patellofemoral instability, Osgood-Schlatter disease, osteochondrosis dissecans are increasingly being found in cases of increased external tibial torsion and arthrosis in reduced torsion. Although spontaneous correction may occur in certain cases, in others the only way to correct the condition is by employing physiologic torsion. Conservative treatment methods such as bandages or orthosis have been shown to not have any effect on torsion; thus, surgical treatment is the only successful way to correct a pathologic angle of rotation of the tibia. For this, supramalleolar osteotomy with fixation using Kirscher wires and plaster or an external fixator are the most common treatments. PMID:11092002

Lampert, C; Thomann, B; Brunner, R

2000-09-01

83

Accounting for conformational flexibility and torsional anharmonicity in the H + CH{sub 3}CH{sub 2}OH hydrogen abstraction reactions: A multi-path variational transition state theory study  

SciTech Connect

This work reports a detailed theoretical study of the hydrogen abstraction reactions from ethanol by atomic hydrogen. The calculated thermal rate constants take into account torsional anharmonicity and conformational flexibility, in addition to the variational and tunneling effects. Specifically, the kinetics calculations were performed by using multi-path canonical variational transition state theory with least-action path tunneling corrections, to which we have added the two-dimensional non-separable method to take into account torsional anharmonicity. The multi-path thermal rate constant is expressed as a sum over conformational reaction channels. Each of these channels includes all the transition states that can be reached by internal rotations. The results show that, in the interval of temperatures between 250 and 2500 K, the account for multiple paths leads to higher thermal rate constants with respect to the single path approach, mainly at low and at high temperatures. In addition, torsional anharmonicity enhances the slope of the Arrhenius plot in this range of temperatures. Finally, we show that the incorporation of tunneling into the hydrogen abstraction reactions substantially changes the contribution of each of the transition states to the conformational reaction channel.

Meana-Pañeda, Rubén; Fernández-Ramos, Antonio, E-mail: qf.ramos@usc.es [Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, 15706 Santiago de Compostela (Spain)] [Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, 15706 Santiago de Compostela (Spain)

2014-05-07

84

Torsion pendulum revisited  

E-print Network

We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model.

Massimo Bassan; Fabrizio De Marchi; Lorenzo Marconi; Giuseppe Pucacco; Ruggero Stanga; Massimo Visco

2013-05-30

85

Torsion pendulum revisited  

E-print Network

We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model.

Bassan, Massimo; Marconi, Lorenzo; Pucacco, Giuseppe; Stanga, Ruggero; Visco, Massimo

2013-01-01

86

Medial femoral torsion.  

PubMed

1. Medial femoral torsion is a common benign, spontaneously resolving deformity of childhood. 2. Nonoperative treatment is ineffective and therefore inappropriate. 3. It is fortunate that surgical correction is rarely necessary, for it carries significant risks of complications. 4. Severe medial femoral torsion is rare but carries the potential for disability. Surgery is the only method of correction, and should be undertaken only for serious persisting disability, not for prophylaxis. PMID:7360502

Staheli, L T

1980-01-01

87

Torsion pendulum revisited  

NASA Astrophysics Data System (ADS)

We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model.

Bassan, Massimo; De Marchi, Fabrizio; Marconi, Lorenzo; Pucacco, Giuseppe; Stanga, Ruggero; Visco, Massimo

2013-10-01

88

Joint torsion equals the determinant invariant.  

E-print Network

A determinant in algebraic $K$-theory is associated to any two almost commuting Fredholm operators. On the other hand, one can calculate a homologically defined invariant known as joint torsion. We answer in the affirmative a conjecture of Richard Carey and Joel Pincus, namely that these two invariants agree. In particular, this implies that joint torsion is norm continuous, depends only on the images of the operators modulo trace class, and satisfies the expected Steinberg relations. Moreover, we show that the determinant invariant of two commuting operators can be computed simply as a determinant on a finite dimensional vector space.

Joseph Migler

89

Quantization of two-dimensional gravity with dynamical torsion  

NASA Astrophysics Data System (ADS)

We consider two-dimensional gravity with dynamical torsion in the BV (Batalin-Vilkovisky) and BLT (Batalin-Lavrov-Tyutin) formalisms of gauge theory quantization, as well as in the background field method.

Lavrov, P. M.; Moshin, P. Yu

1999-07-01

90

Visual reaction times during prolonged angular acceleration parallel the subjective perception of rotation  

NASA Technical Reports Server (NTRS)

The effect of prolonged angular acceleration on choice reaction time to an accelerating visual stimulus was investigated, with 10 commercial airline pilots serving as subjects. The pattern of reaction times during and following acceleration was compared with the pattern of velocity estimates reported during identical trials. Both reaction times and velocity estimates increased at the onset of acceleration, declined prior to the termination of acceleration, and showed an aftereffect. These results are inconsistent with the torsion-pendulum theory of semicircular canal function and suggest that the vestibular adaptation is of central origin.

Mattson, D. L.

1975-01-01

91

Nanomechanical torsional resonators for frequency-shift infrared thermal sensing.  

PubMed

We investigate use of nanomechanical torsional resonators for frequency-shift-based infrared (IR) thermal sensing. Nanoscale torsion rods, ~1 ?m long and 50-100 nm in diameter, provide both extraordinary thermal isolation and excellent angular displacement and torque sensitivities, of order ~10(-7) rad·Hz(-1/2) and ~10(-22) (N·m) Hz(-1/2), respectively. Furthermore, these nanorods act as linear torsional springs, yielding a maximum angular displacement of 3.6° and a dynamic range of over 100 dB; this exceeds the performance of flexural modes by as much as 5 orders of magnitude. These attributes lead to superior noise performance for torsional-mode sensing. We demonstrate the operational principles of torsional-mode IR detection, attaining an uncooled noise equivalent temperature difference (NETD) of 390 mK. By modeling the fundamental noise processes, we project that further reduction of device size can significantly improve thermal responsivity; a room-temperature NETD below 10 mK appears feasible. PMID:23458733

Zhang, X C; Myers, E B; Sader, J E; Roukes, M L

2013-04-10

92

Torsional Vibration Effects in Grinding?  

Microsoft Academic Search

The vast majority of models of vibration in grinding assume that there are no torsional vibration effects. In a recent doctoral study, it was found possible to eliminate grinding chatter by changing the torsional stiffness of the workpiece drive. In that study, a frequency domain model for the grinding process was developed that included torsional effects. It was concluded that

M. A. Mannan; S. J. Drew; B. J. Stone; J. G. Wager

2000-01-01

93

Precision Tilt Measurement for Torsion  

E-print Network

torques #12;Torsion Balances: An Introduction Test fundamental physics at macroscopic scale We get much a torsion balance Composition dipole test mass for equivalence principle (to test universality of freefallPrecision Tilt Measurement for Torsion Balance Experiments Scott Yantek California Institute

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

94

Torsion--treatment indications.  

PubMed

Rotational problems, when outside the normal range, are referred to as torsional deformity. These deformities are relatively common in infancy and childhood, generally resolve spontaneously with growth, and rarely persist into adult life. There are few situations in which treatment is necessary. (1) Rigid metatarsus adductus that does not resolve during the first six months should be corrected by casting. The long leg cast is most effective, as it controls the rotation of the tibia. With the tibia stabilized, the foot can be laterally rotated and abducted, which usually allows correction using one or two casts. (2) Persistent, severe tibial medial or lateral torsion after the age of eight years may be corrected by a supramalleolar tibial rotational osteotomy. This is indicated for medial torsion beyond 15 degrees and for lateral torsion beyond 30 degrees. Fixation is provided by crossed, smooth pins and a long leg cast. Compartment syndromes and peroneal nerve injury are avoided by the distal correction. (3) Persistent, severe femoral antetorsion of more than 50 degrees after the age of eight years may justify correction. For operative correction, medial rotation should exceed 85 degrees and lateral rotation should be less than 10 degrees. The osteotomy for correction is fixed by threaded Steinmann pins cut off below the skin and supplemented with a spica cast. PMID:2676305

Staheli, L T

1989-10-01

95

Angular and Linear Velocity Estimation for a Re-Entry Vehicle Using Six Distributed Accelerometers: Theory, Simulation and Feasibility  

SciTech Connect

This report describes a feasibility study. We are interested in calculating the angular and linear velocities of a re-entry vehicle using six acceleration signals from a distributed accelerometer inertial measurement unit (DAIMU). Earlier work showed that angular and linear velocity calculation using classic nonlinear ordinary differential equation (ODE) solvers is not practically feasible, due to mathematical and numerical difficulties. This report demonstrates the theoretical feasibility of using model-based nonlinear state estimation techniques to obtain the angular and linear velocities in this problem. Practical numerical and calibration issues require additional work to resolve. We show that the six accelerometers in the DAIMU are not sufficient to provide observability, so additional measurements of the system states are required (e.g. from a Global Positioning System (GPS) unit). Given the constraint that our system cannot use GPS, we propose using the existing on-board 3-axis magnetometer to measure angular velocity. We further show that the six nonlinear ODE's for the vehicle kinematics can be decoupled into three ODE's in the angular velocity and three ODE's in the linear velocity. This allows us to formulate a three-state Gauss-Markov system model for the angular velocities, using the magnetometer signals in the measurement model. This re-formulated model is observable, allowing us to build an Extended Kalman Filter (EKF) for estimating the angular velocities. Given the angular velocity estimates from the EKF, the three ODE's for the linear velocity become algebraic, and the linear velocity can be calculated by numerical integration. Thus, we do not need direct measurements of the linear velocity to provide observability, and the technique is mathematically feasible. Using a simulation example, we show that the estimator adds value over the numerical ODE solver in the presence of measurement noise. Calculating the velocities in the presence of significant measurement noise is not feasible with a classic ODE solver. The EKF is able to deal effectively with the noise and provide useful angular velocity estimates. The linear velocity estimates for this simulation show numerical difficulties associated with the nonlinear ODE's and the quadrature operation. Future work will focus on dealing with practical numerical issues and the issue of calibrating the DAIMU to deal with uncertainties in the accelerometer positions and locations.

Clark, G

2003-04-28

96

Evaluation of the torsional VOR in weightlessness.  

PubMed

The experimental concept and findings from a recent manned orbital spaceflight are described. Together with ongoing terrestrial and parabolic studies, the present experiment is intended to further our knowledge of the sensory integrative processing of information from the semicircular canals and the otolithic receptors, and to quantify the presumed otolithic adaptation to altered gravito-inertial force environments in a more reliable manner than to date. The experiment included measurement of the basic vestibulo-oculomotor response during active head rotation about each of the three orthogonal axes. Priority was given to the recording of ocular torsion, as elicited by head oscillation about the roll axis, and thus due to the concomitant stimulation of the semicircular canals and otolith receptors. Videooculography was employed for the measurement of eye movements; head movement was measured by three orthogonally arranged angular rate sensors and a triaxial linear accelerometer device. All signals were recorded synchronously on a video/data recorder. Preliminary results indicate alterations in the torsional VOR under zero-g conditions, suggesting an adaptive modification of the torsional VOR gain over the course of the 6-day orbital flight. In addition, the inflight test findings yielded discrepancies between intended and performed head movement, indicating impairment in sensorimotor coordination under prolonged microgravity conditions. PMID:8275257

Clarke, A H; Teiwes, W; Scherer, H

1993-01-01

97

CONTINUOUSLY CONTROLLED SURGERY THEORY ERIK KJAER PEDERSEN  

E-print Network

CONTINUOUSLY CONTROLLED SURGERY THEORY ERIK KJAER developed later [14, 29]. Chapman * *developed a controlled Whitehead torsion theory using geometric, 24, 15] and the controlled torsion and surgery o* *bstructions live in the K and L-theory

Pedersen, Erik Kjær

98

Quantum-mechanical theory including angular momenta analysis of atom-atom collisions in a laser field  

NASA Technical Reports Server (NTRS)

The problem of two atoms colliding in the presence of an intense radiation field, such as that of a laser, is investigated. The radiation field, which couples states of different electronic symmetry, is described by the number state representation while the electronic degrees of freedom (plus spin-orbit interaction) are discussed in terms of a diabatic representation. The total angular momentum of the field-free system and the angular momentum transferred by absorption (or emission) of a photon are explicitly considered in the derivation of the coupled scattering equations. A model calculation is discussed for the Xe + F collision system.

Devries, P. L.; George, T. F.

1978-01-01

99

Primordial magnetic fields and dynamos from parity violated torsion  

NASA Astrophysics Data System (ADS)

It is well known that torsion induced magnetic fields may seed galactic dynamos, but the price one pays for that is the conformal and gauge invariance breaks and a tiny photon mass. More recently I have shown [L.C. Garcia de Andrade, Phys. Lett. B 468 (2011) 28] that magnetic fields decay in a gauge invariant non-minimal coupling theory of torsion is slow down, which would allow for dynamo action to take place. In this Letter, by adding a parity violation term of the type R? to the non-coupling term, a magnetic dynamo equation is obtained. From dynamo equation it is shown that torsion terms only appear in the dynamo equation when diffusion in the cosmic plasma is present. Torsion breaks the homogeneity of the magnetic field in the universe. Since Zeldovich anti-dynamo theorem assumes that the spacetime should be totally flat, torsion is responsible for violation of anti-dynamo theorem in 2D spatial dimensions. Contrary to previous results torsion induced primordial magnetic fields cannot seed galactic dynamos since from torsion and diffusion coefficient the decaying time of the magnetic field is 106yrs, which is much shorter than the galaxy age.

Garcia de Andrade, L. C.

2012-05-01

100

Constraining spacetime torsion with the Moon and Mercury  

E-print Network

We report a search for new gravitational physics phenomena based on Einstein-Cartan theory of General Relativity including spacetime torsion. Starting from the parametrized torsion framework of Mao, Tegmark, Guth and Cabi, we analyze the motion of test bodies in the presence of torsion, and in particular we compute the corrections to the perihelion advance and to the orbital geodetic precession of a satellite. We describe the torsion field by means of three parameters, and we make use of the autoparallel trajectories, which in general may differ from geodesics when torsion is present. We derive the equations of motion of a test body in a spherically symmetric field, and the equations of motion of a satellite in the gravitational field of the Sun and the Earth. We calculate the secular variations of the longitudes of the node and of the pericenter of the satellite. The computed secular variations show how the corrections to the perihelion advance and to the orbital de Sitter effect depend on the torsion parameters. All computations are performed under the assumptions of weak field and slow motion. To test our predictions, we use the measurements of the Moon geodetic precession from lunar laser ranging data, and the measurements of Mercury's perihelion advance from planetary radar ranging data. These measurements are then used to constrain suitable linear combinations of the torsion parameters.

Riccardo March; Giovanni Bellettini; Roberto Tauraso; Simone Dell'Agnello

2011-03-28

101

Constraining spacetime torsion with the Moon and Mercury  

SciTech Connect

We report a search for new gravitational physics phenomena based on Riemann-Cartan theory of general relativity including spacetime torsion. Starting from the parametrized torsion framework of Mao, Tegmark, Guth, and Cabi, we analyze the motion of test bodies in the presence of torsion, and, in particular, we compute the corrections to the perihelion advance and to the orbital geodetic precession of a satellite. We consider the motion of a test body in a spherically symmetric field, and the motion of a satellite in the gravitational field of the Sun and the Earth. We describe the torsion field by means of three parameters, and we make use of the autoparallel trajectories, which in general differ from geodesics when torsion is present. We derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of celestial mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter of the satellite. The computed secular variations show how the corrections to the perihelion advance and to the orbital de Sitter effect depend on the torsion parameters. All computations are performed under the assumptions of weak field and slow motion. To test our predictions, we use the measurements of the Moon's geodetic precession from lunar laser ranging data, and the measurements of Mercury's perihelion advance from planetary radar ranging data. These measurements are then used to constrain suitable linear combinations of the torsion parameters.

March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Dell'Agnello, Simone [Istituto per le Applicazioni del Calcolo, CNR, Via dei Taurini 19, 00185 Roma, Italy, and INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy); Dipartimento di Matematica, Universita di Roma ''Tor Vergata'', via della Ricerca Scientifica 1, 00133 Roma, Italy, and INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy); Dipartimento di Matematica, Universita di Roma 'Tor Vergata', via della Ricerca Scientifica 1, 00133 Roma, Italy, and INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy); INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy)

2011-05-15

102

Torsional actuation with extension-torsion composite coupling and a magnetostrictive actuator  

NASA Astrophysics Data System (ADS)

An analytical-experimental study of using magnetostrictive actuators in conjunction with an extension-torsion coupled composite tube to actuate a rotor blade trailing-edge flap to actively control helicopter vibration is presented. Thin walled beam analysis based on Vlasov theory was used to predict the induced twist and extension in a composite tube with magnetostrictive actuation. The study achieved good correlation between theory and experiment. The Kevlar-epoxy systems showed good correlation between measured and predicted twist values.

Bothwell, Christopher M.; Chandra, Ramesh; Chopra, Inderjit

1995-04-01

103

Universe in a black hole with spin and torsion  

E-print Network

The conservation law for the angular momentum in curved spacetime requires that the antisymmetric part of the affine connection (the torsion tensor) is a variable in the principle of least action. The coupling between spin and torsion generates gravitational repulsion in fermionic matter at extremely high densities and avoids the formation of singularities in black holes. We show that every black hole in the presence of torsion forms a nonsingular, closed, nearly flat, homogeneous, and isotropic universe on the other side of its event horizon. Quantum particle production in such a universe can generate a period of exponential expansion which creates an enormous amount of matter in that universe. Accordingly, our Universe may have originated from the interior of a black hole existing in another universe.

Nikodem J. Poplawski

2014-10-14

104

Torsional Ratcheting Actuating System  

SciTech Connect

A new type of surface micromachined ratcheting actuation system has been developed at the Microelectronics Development Laboratory at Sandia National Laboratories. The actuator uses a torsional electrostatic comb drive that is coupled to an external ring gear through a ratcheting scheme. The actuator can be operated with a single square wave, has minimal rubbing surfaces, maximizes comb finger density, and can be used for open-loop position control. The prototypes function as intended with a minimum demonstrated operating voltage of 18V. The equations of motion are developed for the torsional electrostatic comb drive. The resonant frequency, voltage vs. displacement and force delivery characteristics are predicted and compared with the fabricated device's performance.

BARNES,STEPHEN MATTHEW; MILLER,SAMUEL L.; RODGERS,M. STEVEN; BITSIE,FERNANDO

2000-01-24

105

Performance of an angular flange aeroelastic wind energy converter  

SciTech Connect

ALL conventional wind turbines operate on the principles of turbomachinaries, with wind being made to flow over a set of rotating vanes. Recently, a new concept for wind energy conversion based on aeroelastic instability was introduced. It is well known that couplings between the vibration of an elastic structure and fluid stream may lead to aeroelastic instability. Energy then is transferred from the airstream into the elastic structure, which results in a destructive monotonic increase of the vibration amplitude of the structure. The failure of the Tacoma Narrows Bridge is one of the well-known examples of such a disaster. The use of an aeroelastic instability (or flutter) mechanism for constructing a wind energy converter was suggested. The theory for a torsional wind energy converter and the results of some model tests were also presented. Recently, some studies on similar types of wind energy converters using oscillating airfoils were reported. In the present study an angular flange H-section model of a torsional aeroelastic wind energy converter is constructed, and its performances under various conditions are investigated. The effects of the variations of the flange angle and the flange width on the performance of the model are studied. The weight of the pendulum is also varied, and its effects on the power coefficient of the model are investigated. It is observed that the efficiency of energy conversion decreases with an increase in wind speed. A method for possible improvement of the theoretical prediction is suggested and discussed.

Ahmadi, G.

1983-05-01

106

Torsional surface waves in a gradient-elastic half-space  

Microsoft Academic Search

The present work deals with torsional wave propagation in a linear gradient-elastic half-space. More specifically, we prove that torsional surface waves (i.e. waves with amplitudes exponentially decaying with distance from the free surface) do exist in a homogeneous gradient-elastic half-space. This finding is in contrast with the well-known result of the classical theory of linear elasticity that torsional surface waves

H. G. Georgiadis; I. Vardoulakis; G. Lykotrafitis

2000-01-01

107

ORIGINAL ARTICLE Torsional Anomalous Retinal Correspondence  

E-print Network

anomalous retinal correspondence (HARC). Torsional strabismus with HARC provides a similar functional documented torsional strabismus and torsional HARC. Methods. Monocular visual fields under binocular fixation strabismus (along with exotropia and right hypertropia) with congenital homonymous hemianopia was compared

Peli, Eli

108

Neutral-meson oscillations with torsion  

E-print Network

We propose a simple mechanism that may explain the observed particle-antiparticle asymmetry in the Universe. In the Einstein-Cartan-Sciama-Kibble theory of gravity, the intrinsic spin of matter generates spacetime torsion. Classical Dirac fields in the presence of torsion obey the nonlinear Hehl-Datta equation which is asymmetric under a charge-conjugation transformation. Accordingly, at extremely high densities that existed in the very early Universe, fermions have higher effective masses than antifermions. As a result, a meson composed of a light quark and a heavy antiquark has a lower effective mass than its antiparticle. Neutral-meson oscillations in thermal equilibrium therefore favor the production of light quarks and heavy antiquarks, which may be related to baryogenesis.

Nikodem J. Poplawski

2011-04-30

109

Theoretical-experimental correlation for buckling of composite cylinders under combined compression and torsion  

NASA Technical Reports Server (NTRS)

Comparison between theory and experiment for buckling of laminated graphite-epoxy and boron-epoxy cylinders under combined compression and torsion are presented. The experimental results are compared to a theory by Wu. It is shown that there is excellent agreement between theory and experiment for pure torsional loading (positive and negative), experimental buckling loads for pure compression are well below the predicted values, and good correlation is exhibited between theory and experiment for buckling under combined loading when compared in the form of normalized buckling interaction diagrams in axial-torsional load space.

Herakovich, C. T.

1978-01-01

110

Angular Momentum  

ERIC Educational Resources Information Center

The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in…

Shakur, Asif; Sinatra, Taylor

2013-01-01

111

Torsion as a source of expansion in a Bianchi type-I universe in the self-consistent Einstein-Cartan theory of a perfect fluid with spin density  

NASA Technical Reports Server (NTRS)

It is shown that a generalized (or 'power law') inflationary phase arises naturally and inevitably in a simple (Bianchi type-I) anisotropic cosmological model in the self-consistent Einstein-Cartan gravitation theory with the improved stress-energy-momentum tensor with the spin density of Ray and Smalley (1982, 1983). This is made explicit by an analytical solution of the field equations of motion of the fluid variables. The inflation is caused by the angular kinetic energy density due to spin. The model further elucidates the relationship between fluid vorticity, the angular velocity of the inertially dragged tetrads, and the precession of the principal axes of the shear ellipsoid. Shear is not effective in damping the inflation.

Bradas, James C.; Fennelly, Alphonsus J.; Smalley, Larry L.

1987-01-01

112

Dynamics of the I + HI --> IH + I reaction: application of nearside-farside, local angular momentum and resummation theories using the Fuller and Hatchell decompositions.  

PubMed

The differential cross section (DCS) for the I + HI(v(i) = 0, j(i) = 0) --> IH(v(f) = 0, j(f) = 2) + I reaction at a translational energy of 21.3 meV is studied, where v(i), j(i) and v(f), j(f) are vibrational, rotational quantum numbers for the initial and final states respectively. We apply new theoretical developments (since 2001) in nearside-farside (NF) theory to provide insights into intricate oscillatory structures in its DCS. It is shown that a simple physically-meaningful parameterization of the scattering (S) matrix, using a background Gaussian term plus a single Regge pole and a quadratic phase, can reproduce, in the forward and sideward directions, the intricate angular scattering obtained from numerical S matrix elements computed from a quantum Born-Oppenheimer-Centrifugal-Sudden scattering technique. This encouraging result suggests that many S matrix elements obtained from computer-intensive calculations can be parameterized in a similar physically-meaningful way. The manner in which the full and NF DCSs change when the Regge pole becomes progressively less important compared to the Gaussian term is also investigated. We report the first application to reactive scattering of the Hatchell NF decomposition, including resummations of the Legendre partial wave series for the scattering amplitude. The Hatchell NF resummed DCSs are compared with the corresponding Fuller NF resummed DCSs for resummation orders of r = 0, 1, 2 and 3. We find that the Fuller NF decomposition always provides a better physical interpretation of the angular scattering. Resummation usually cleans the NF DCSs of unphysical oscillations, especially in the farside (F) DCSs, with the greatest cleaning effect on going from no resummation (r = 0) to first order resummation (r = 1). Identities are derived which relate the Fuller and Hatchell NF subamplitudes for resummation orders, r > 0, to the NF unresummed subamplitudes, r = 0. These identities help us understand the origin of unexpected peaks, which sometimes appear in NF resummed DCSs, together with a simple procedure to remove them. We report Local Angular Momentum (LAM) and DCS x LAM (CLAM) analyses of the angular scattering for r = 0 and r = 1 using the Fuller NF decomposition. The LAM and CLAM analyses provide complementary (yet consistent) information to that obtained from the NF resummed DCSs. It is shown that the "l window representation", as used to analyse elastic scattering in the presence of strong absorption, is a special case of the general resummation theory developed in this paper. PMID:20498904

Totenhofer, A J; Noli, C; Connor, J N L

2010-08-21

113

Tree level Leptogenesis from Kalb-Ramond Torsion Background  

E-print Network

The effect of torsion in theories of quantum gravity is known to be well described by an axion-like field which couples to matter as well as to gravitation and radiation gauge fields. In this note we consider a particular kind of torsion, arising from the Kalb-Ramond antisymmetric tensor field that appears in the gravitational multiplet of string theory. We investigate the implications for leptogenesis. It is shown that leptogenesis can occur even at tree-level and with only one generation of right-handed Majorana neutrinos, due to CP and CPT violation introduced by the background geometry.

de Cesare, M; Sarkar, Sarben

2014-01-01

114

Internal Symmetry of Space-Time Connections with Torsion  

E-print Network

In this brief article an internal symmetry of a generic metric compatible space-time connection, metric and generalized volume element is introduced. The symmetry arises naturally by considering a space-time connection containing a generic torsion tensor, and would otherwise be missed in the absence of torsion. When the transformation is applied to the Hilbert-Einstein action it is shown that by a choice of gauge all possible field theories arising from the Hilbert-Einstein action are equivalent to the standard theory of gravity described by general relativity.

David Robert Bergman

2014-11-19

115

Torsion-rotation intensities in methanol  

NASA Astrophysics Data System (ADS)

Methanol exists in numerous kinds of astronomical objects featuring a wide range of local conditions. The light nature of the molecule coupled with the internal rotation of the methyl group with respect to the hydroxyl group results in a rich, strong spectrum that spans the entire far-infrared region. As a result, any modest size observational window will have a number of strong methanol transitions. This has made it the gas of choice for testing THz receivers and to extract the local physical conditions from observations covering small frequency windows. The latter has caused methanol to be dubbed the Swiss army knife of astrophysics. Methanol has been increasingly used in this capacity and will be used even more for subsequent investigations into the Herschel archive, and with SOFIA and ALMA. Interpreting physical conditions on the basis of a few methanol lines requires that the molecular data, line positions, intensities, and collision rates, be complete, consistent and accurate to a much higher level than previously required for astrophysics. The need for highly reliable data is even more critical for modeling the two classes of widespread maser action and many examples of optical pumping through the torsional bands. Observation of the torsional bands in the infrared will be a unique opportunity to directly connect JWST observations with those of Herschel, SOFIA, and ALMA. The theory for the intensities of torsion-rotation transitions in a molecule featuring a single internally rotating methyl group is well developed after 70 years of research. However, other than a recent very preliminary and not completely satisfactory investigation of a few CH3OH torsional bands, this theory has never been experimentally tested for any C3V internal rotor. More alarming is a set of recent intensity calibrated microwave measurements that showed deviations relative to calculations of up to 50% in some ground state rotational transitions commonly used by astronomers to extract local conditions. We propose a comprehensive study of the intensities of methanol involving both the pure rotation bands and the torsional bands to serve as a benchmark for the theory used to calculate the infrared activity of all single methyl internal rotation molecules.

Pearson, John

116

Transverse angular momentum of photons  

NASA Astrophysics Data System (ADS)

We develop the quantum theory of transverse angular momentum of light beams. The theory applies to paraxial and quasiparaxial photon beams in vacuum and reproduces the known results for classical beams when applied to coherent states of the field. Both the Poynting vector, alias the linear momentum, and the angular-momentum quantum operators of a light beam are calculated including contributions from first-order transverse derivatives. This permits a correct description of the energy flow in the beam and the natural emergence of both the spin and the angular momentum of the photons. We show that for collimated beams of light, orbital angular-momentum operators do not satisfy the standard commutation rules. Finally, we discuss the application of our theory to some concrete cases.

Aiello, Andrea; Marquardt, Christoph; Leuchs, Gerd

2010-05-01

117

General relativity with spin and torsion: Foundations and prospects  

Microsoft Academic Search

A generalization of Einstein's gravitational theory is discussed in which the spin of matter as well as its mass plays a dynamical role. The spin of matter couples to a non-Riemannian structure in space-time, Cartan's torsion tensor. The theory which emerges from taking this coupling into account, the Uâ theory of gravitation, predicts, in addition to the usual infinite-range gravitational

Friedrich W. Hehl; Paul von der Heyde; G. David Kerlick; J. M. Nester

1976-01-01

118

Angular momentum  

NASA Astrophysics Data System (ADS)

The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in the physics laboratory. Many traditional physics experiments can now be performed very conveniently in a pedagogically enlightening environment while simultaneously reducing the laboratory budget substantially by using student-owned smartphones.

Shakur, Asif; Sinatra, Taylor

2013-12-01

119

Angular Measure  

NSDL National Science Digital Library

Students will learn about the Transit of Venus through reading a NASA press release and viewing a NASA eClips video that describes several ways to observe transits. Then students will study angular measurement by learning about parallax and how astronomers use this geometric effect to determine the distance to Venus during a Transit of Venus. This activity is part of the Space Math multimedia modules that integrate NASA press releases, NASA archival video, and mathematics problems targeted at specific math standards commonly encountered in middle school textbooks. The modules cover specific math topics at multiple levels of difficulty with real-world data and use the 5E instructional sequence.

120

Twisted ultrathin silicon nanowires: A possible torsion electromechanical nanodevice  

NASA Astrophysics Data System (ADS)

Nanowires have been considered for a number of applications in nanometrology. In such a context, we have explored the possibility of using ultrathin twisted nanowires as torsion nanobalances to probe forces and torques at molecular level with high precision, a nanoscale system analogous to the Coulomb's torsion balance electrometer. In order to achieve this goal, we performed a first-principles investigation on the structural and electronic properties of twisted silicon nanowires, in their pristine and hydrogenated forms. The results indicated that wires with pentagonal and hexagonal cross-sections are the thinnest stable silicon nanostructures. Additionally, all wires followed a Hooke's law behavior for small twisting deformations. Hydrogenation leads to spontaneous twisting, but with angular spring constants considerably smaller than the ones for the respective pristine forms. We observed considerable changes on the nanowire electronic properties upon twisting, which allows to envision the possibility of correlating the torsional angular deformation with the nanowire electronic transport. This could ultimately allow a direct access to measurements on interatomic forces at molecular level.

Garcia, J. C.; Justo, J. F.

2014-11-01

121

Torsional osteotomies of the femur.  

PubMed

Various pathologies of the hip or knee, such as patellofemoral malalignment or femoroacetabular impingement may be caused by a femoral torsional deformity. When diagnosed and analyzed, it is treated by femoral torsional osteotomy. Thirty femoral torsional osteotomies in 25 patients were included, the principal symptoms were patellar dislocation in 15 patients, anterior knee pain in 17, and femoroacetabular impingement in two. A computed-tomography-based measurement of the torsional angle was performed in all patients. Japanese Knee Society score, Tegner activity score, Lysholm score, and visual analog scale score were determined before surgery and at follow-up after 41 (6-113) months. Femoral internal torsion was on average 40.9° (29°?-?66°; normal 24°). Surgical treatment consisted of a femoral external torsional osteotomy of on average 13.8° (5°?-?26°). Tegner activity score increased non-significantly (p-value 0.326) from 3.57 to 3.71. Japanese Knee Society score improved significantly from 72 to 87 (p-value 0.004) while Lysholm score rose significantly from 66 to 84 points (p-value 0.004). Pain relief was demonstrated by a significant decrease in the VAS score from 5.6 to 2.4 (p-value 0.007). No further patellar dislocation was reported. Torsional deformities of the femur frequently cause symptoms in the knee or hip joint. After thorough assessment and diagnostic investigation, a femoral external torsional osteotomy provides significant pain relief as well as patellofemoral stability. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. PMID:25399673

Dickschas, Jörg; Harrer, Jörg; Reuter, Benoit; Schwitulla, Judith; Strecker, Wolf

2014-11-17

122

Plastic Behavior and Fracture of Aluminum and Copper in Torsion Tests  

NASA Astrophysics Data System (ADS)

Present work investigates the plastic behavior, work hardening and the beginning of plastic instabilities, of cylindrical specimens deformed by high speed cold plastic torsion tests and at low speed tensile test. The tests were carried out in a laboratory torsion test equipment and an universal tensile test machine. The tensile tests were performed at room temperature in an universal testing machine at low strain rate of 0.034/s. Experimental torsion tests were carried out at constant angular speed that imposed a constant shear strain rate to the specimen. In the tests, the rotation speed were set to 62 rpm and 200 rpm which imposed high strain rates of about 2/s and 6.5/s respectively. The torsion tests performed at room temperature on annealed commercial pure copper and aluminum. Two types of torsion specimen for aluminum were used: solid and tubular. The solid aluminum specimen curves presented various points of maximum torque. The tubular copper specimens showed two points of maximum. Shear bands or shear strain localization at specimen were possibly the mechanism of maximum torque points formation. The work hardening coefficient n and the strain rate sensitivity parameter m were evaluated from the equivalent stress versus strain curve from tensile and torsion tests. The n-value remained constant whereas the m-value increased ten folds for aluminum specimens: from tensile test m= 0.027 and torsion test m= 0.27. However, the hardening curves were sigmoidal.

Bressan, José Divo

2007-04-01

123

The torsion index of the spin groups  

Microsoft Academic Search

We compute Grothendieck's torsion index of the compact Lie group ${\\\\rm Spin}(n)$ for any $n$ . We explain the applications of the torsion index to topology and to the study of splitting fields for quadratic forms.

Burt Totaro

124

Tibiofibular torsion in congenital clubfoot.  

PubMed

Tibiofibular torsion was measured by computed tomography in three series of patients affected by congenital clubfoot who were treated with different protocols. The normal leg of unilateral deformities served as the control. For the bilateral cases, only the right side was included in the study. The angle between the bicondylar axis of the tibia and the bimalleolar axis was the index of tibiofibular torsion. There were 34 clubfeet in the first series, treated with a posteromedial release, and 40 clubfeet in the second series, treated with a modified Ponseti method, whereas the third series included 16 clubfeet, treated with the original Ponseti method. All 90 clubfeet were graded at birth as group 3 according to the Manes classification. No patient had previous treatment. The patients of the first and the second series were followed up to maturity, whereas the patients of the third series were followed up to a maximum of 11 years of age. In the congenital clubfoot, the tibia and the fibula were externally rotated, in comparison with the normal leg; in fact, the average value of the angle of tibiofibular torsion was 32.2° in the first series, 23.9° in the second series, and 21.1° in the third series. In the normal tibiae, the average value of the angle of tibiofibular torsion was 21.4°. The difference between the first series and the normal controls was statistically significant, as was the difference between the first one and the other two series. The value of the tibiofibular torsion angle seems to be related to the manipulation technique used to treat clubfoot: when the manipulation does not allow a progressive eversion of the talus underneath the calcaneus, the external tibial torsion increases. At follow-up, an intoeing gait was present in seven treated clubfeet of the first series. In all of them except one, the highest value of the external tibial torsion angle was observed, with a low value of the Kite's angle and/or residual forefoot adduction. In the treated congenital clubfoot, persistent intoeing is not related to the angle of tibial torsion but rather to the amount of correction of calcaneal inversion and residual forefoot adduction. PMID:22027706

Farsetti, Pasquale; Dragoni, Massimiliano; Ippolito, Ernesto

2012-01-01

125

Reply to the Comment of X. Ji on "Spin and orbital angular momentum in gauge theories" [PRL 100:232002 (2008)  

E-print Network

We reply to the Comment of X. Ji [arXiv:0810.4913] on our paper [PRL 100:232002 (2008)], concerning angular momentum algebra, locality, Lorentz covariance, and measurability of our gauge-invariant description of the spin and orbital angular momentum of quarks and gluons.

Xiang-Song Chen; Xiao-Fu Lü; Wei-Min Sun; Fan Wang; T. Goldman

2008-12-23

126

Non-linear torsional vibration characteristics of an internal combustion engine crankshaft assembly  

NASA Astrophysics Data System (ADS)

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines. The linear lumped mass method, which has been universally applied to the dynamic modeling of engine crankshaft assembly, reveals obvious simulation errors. The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness. In this paper, a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method. The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments. The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method. The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method. The simulation results are compared with a lumped mass model and a detailed model using the system matrix method. Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration, and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor. The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia. This research project is aimed at improving nonlinear dynamics theory, and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.

Huang, Ying; Yang, Shouping; Zhang, Fujun; Zhao, Changlu; Ling, Qiang; Wang, Haiyan

2012-07-01

127

Weak Forces and Neutrino Oscillations under the standards of Hybrid Gravity with Torsion  

E-print Network

We present a unifying approach where weak forces and neutrino oscillations are interpreted under the same standards of torsional hybrid gravity. This gravitational theory mixes metric and metric-affine formalism in presence of torsion and allows to derive an effective scalar field which gives rise to a running coupling for Dirac matter fields. In this picture, two phenomena occurring at different energy scales can be encompassed under the dynamics of such a single scalar field, which represents the further torsional and curvature degrees of freedom.

Salvatore Capozziello; Luca Fabbri; Stefano Vignolo

2013-09-16

128

Metric-affine $f(R)$-gravity with torsion: an overview  

E-print Network

Torsion and curvature could play a fundamental role in explaining cosmological dynamics. f(R)-gravity with torsion is an approach aimed to encompass in a comprehensive scheme all the Dark Side of the Universe (Dark Energy and Dark Matter). We discuss the field equations in empty space and in presence of perfect fluid matter taking into account the analogy with the metric-affine formalism. The result is that the extra curvature and torsion degrees of freedom can be dealt under the standard of an effective scalar field of fully geometric origin. The initial value problem for such theories is also discussed.

S. Capozziello; S. Vignolo

2009-10-27

129

Bistability of a Torsion Magnetometer  

E-print Network

Low-level bistability has been observed in the output from a recently developed novel magnetometer. It is not known whether this behavior is associated with the torsion fiber of the instrument or with the Earth's magnetic field. Whatever its cause, this form of complexity is not widely known.

Randall D. Peters

2002-07-16

130

Les torsions sur testicules cryptorchides  

PubMed Central

Résumé But : La cryptorchidie est une pathologie assez fréquente en urologie. Elle est associée à un risque élevé d’infertilité et de dégénérescence. Elle semble aussi être associée à un risque important de torsion. Cette entité est très peu abordée dans la littérature. Nous rapportons tous les cas de torsion sur testicule cryptorchide observés à notre service dans le but de mieux caractériser cette pathologie et de réduire ainsi le taux d’orchidectomies. Méthodologie : Il s’agit d’une étude rétrospective portant sur tous les cas de torsion sur testicule cryptorchide opérés dans notre service d’urologie entre 1999 et 2007. Les patients ont fait l’objet d’une description basée sur le résumé de leurs observations. Résultats : Les patients étaient âgés de 7 mois à 39 ans. La torsion touchait le testicule droit dans 53 % des cas. Le tableau clinique comportait une douleur au niveau de la région inguinale d’apparition soudaine avec une masse sous-cutanée inflammatoire et douloureuse à ce niveau et surtout un hémiscrotum homolatéral vide. Dans 60 % des cas, le diagnostic était tardif et une orchidectomie a été réalisée. Dans les autre cas, un abaissement du testicule a été réalisé avec orchidopexie controlatéral dans le même temps opératoire. Conclusion : Bien qu’il s’agisse d’une pathologie peu courante, la torsion sur testicule cryptorchide doit être étudiée davantage. Le diagnostic précoce permettra de sauver et d’abaisser le testicule et faciliter ainsi le dépistage d’une éventuelle dégénérescence. PMID:21191497

Gharbi, Mohamed; Amri, Najmeddine; Chambeh, Wahib; Braiek, Salem; Kamel, Rafik El

2010-01-01

131

Relativistic Statistical Mechanics with Angular Momentum  

E-print Network

The equilibrium distribution function of a relativistic ideal gas has been derived to include the effect of angular momentum. The result agrees with the one obtained from kinetic theory, and consistent with relativistic thermodynamics. The role of angular momentum becomes transparent in this derivation, and the equilibrium distribution can be generalized to accommodate the effect of intrinsic angular momentum. The results here is for a flat spacetime, however, same approach can be applied to static curved spacetimes.

Tadas K Nakamura

2011-12-01

132

Joint torsion of several commuting operators.  

E-print Network

We introduce the notion of joint torsion for several commuting operators satisfying a Fredholm condition. This new secondary invariant takes values in the group of invertibles of a field. It is constructed by comparing determinants associated with different filtrations of a Koszul complex. Our notion of joint torsion generalizes the Carey-Pincus joint torsion of a pair of commuting Fredholm operators. As an example, under more restrictive invertibility assumptions, we show that the joint torsion recovers the multiplicative Lefschetz numbers. Furthermore, in the case of Toeplitz operators over the polydisc we provide a link between the joint torsion and the Cauchy integral formula. We will also consider the algebraic properties of the joint torsion. They include a cocycle property, a symmetry property, a triviality property and a multiplicativity property. The proof of these results relies on a quite general comparison theorem for vertical and horizontal torsion isomorphisms associated with certain diagrams of chain complexes.

Jens Kaad

133

Shaft instantaneous angular speed for blade vibration in rotating machine  

NASA Astrophysics Data System (ADS)

Reliable blade health monitoring (BHM) in rotating machines like steam turbines and gas turbines, is a topic of research since decades to reduce machine down time, maintenance costs and to maintain the overall safety. Transverse blade vibration is often transmitted to the shaft as torsional vibration. The shaft instantaneous angular speed (IAS) is nothing but the representing the shaft torsional vibration. Hence the shaft IAS has been extracted from the measured encoder data during machine run-up to understand the blade vibration and to explore the possibility of reliable assessment of blade health. A number of experiments on an experimental rig with a bladed disk were conducted with healthy but mistuned blades and with different faults simulation in the blades. The measured shaft torsional vibration shows a distinct difference between the healthy and the faulty blade conditions. Hence, the observations are useful for the BHM in future. The paper presents the experimental setup, simulation of blade faults, experiments conducted, observations and results.

Gubran, Ahmed A.; Sinha, Jyoti K.

2014-02-01

134

Combined bending-torsion fatigue reliability. III  

NASA Technical Reports Server (NTRS)

Results generated by three, unique fatigue reliability research machines which can apply reversed bending loads combined with steady torque are presented. AISI 4340 steel, grooved specimens with a stress concentration factor of 1.42 and 2.34, and Rockwell C hardness of 35/40 were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and stress-to-failure data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one represents the data best. The effects of the groove, and of the various combined bending-torsion loads, on the S-N and Goodman diagrams are determined. Two design applications are presented which illustrate the direct useability and value of the distributional failure governing strength and cycles-to-failure data in designing for specified levels of reliability and in predicting the reliability of given designs.

Kececioglu, D.; Chester, L. B.; Nolf, C. F., Jr.

1975-01-01

135

An explanation of forms of planetary orbits and estimation of angular shift of the Mercury' perihelion using the statistical theory of gravitating spheroidal bodies  

NASA Astrophysics Data System (ADS)

This work develops a statistical theory of gravitating spheroidal bodies to calculate the orbits of planets and explore forms of planetary orbits with regard to the Alfvén oscillating force [1] in the Solar system and other exoplanetary systems. The statistical theory of formation of gravitating spheroidal bodies has been proposed in [2]-[5]. Starting the conception for forming a spheroidal body inside a gas-dust protoplanetary nebula, this theory solves the problem of gravitational condensation of a gas-dust protoplanetary cloud with a view to planetary formation in its own gravitational field [3] as well as derives a new law of the Solar system planetary distances which generalizes the wellknown laws [2], [3]. This work also explains an origin of the Alfvén oscillating force modifying forms of planetary orbits within the framework of the statistical theory of gravitating spheroidal bodies [5]. Due to the Alfvén oscillating force moving solid bodies in a distant zone of a rotating spheroidal body have elliptic trajectories. It means that orbits for the enough remote planets from the Sun in Solar system are described by ellipses with focus in the origin of coordinates and with small eccentricities. The nearby planet to Sun named Mercury has more complex trajectory. Namely, in case of Mercury the angular displacement of a Newtonian ellipse is observed during its one rotation on an orbit, i.e. a regular (century) shift of the perihelion of Mercury' orbit occurs. According to the statistical theory of gravitating spheroidal bodies [2]-[5] under the usage of laws of celestial mechanics in conformity to cosmogonic bodies (especially, to stars) it is necessary to take into account an extended substance called a stellar corona. In this connection the stellar corona can be described by means of model of rotating and gravitating spheroidal body [5]. Moreover, the parameter of gravitational compression ? of a spheroidal body (describing the Sun, in particular) has been estimated on the basis of the linear size of its kernel, i.e. the thickness of a visible part of the solar corona. Really, NASA' astronomer S. Odenwald in his notice «How thick is the solar corona?» wrote: "The corona actually extends throughout the entire solar system as a "wind" of particles, however, the densist parts of the corona is usually seen not more than about 1-2 solar radii from the surface or about 690,000 to 1.5 million kilometers at the equator. Near the poles, it seems to be a bit flatter..." [6]. In the fact, as mentioned in [5], a recession of plots of dependences of relative brightness of components of spectrum of the Solar corona occurs on distance of 3-3.5 radii from the center, i.e. on 2-2.5 radii from the edge of the solar disk. Thus, accepting thickness of a visible part of the solar corona equal to ? = 2R (here R is radius of the solar disk) we find that r* = R + ? = 3R , where r* =1/ ? . In other words, the parameter of gravitational compression 2 ? =1/ r* of a spheroidal body in case of the Sun with its corona (for which the equatorial radius ofdisk R = 6.955?108 m) can be estimated by the value [2]-[5]: 2.29701177718 10 (m ) (3 ) 1 19 2 2 = ? ? - - R ? . (1) So, the procedure of finding ? is based on the known 3? -rule in the statistical theory. Really, as shown in the monograph [5], namely the solar corona accounting under calculation of perturbed orbit of the planet of Mercury allows to find the estimation of a displacement of perihelion of Mercury' orbit for the one period within the framework of the statistical theory of gravitating spheroidal bodies. As it is known, on a way of specification of the law of Newton using the general relativity theory the Mercury problem solving was found [5]. Nevertheless, from a common position of the statistical theory of gravitating spheroidal bodies the points of view as Leverrier (about existence of an unknown matter) and Einstein (about insufficiency of the theory of Newton) practically differ nothing. Really, there exist plasma as well as gas-dust substance

Krot, A. M.

2013-09-01

136

On determining G using a cryogenic torsion pendulum  

NASA Astrophysics Data System (ADS)

A measurement of G which will use a torsion pendulum in the `dynamic' (time-of-swing) mode, measuring the influence of field source masses on the pendulum's oscillation period, is being prepared at UC Irvine. Features of the design include: (i) operation at cryogenic temperature (2 K) to reduce thermal noise and increase frequency stability and for ease of magnetic shielding, (ii) large pendulum oscillation amplitudes to increase signal-to-noise ratio and reduce the effect of amplitude-determination error, (iii) use of a pair of source mass rings to produce an extremely uniform field gradient; and (iv) use of a thin quartz plate as a torsion pendulum to minimize sensitivity to pendulum density inhomogeneity and dimensional uncertainties. The `dynamic' method to be used has the great advantage of requiring no angular displacement measurement or calibrating force, but, as pointed out by Kuroda, the method is subject to systematic error associated with the anelastic properties of a torsion fibre. We demonstrate that, for the linear anelasticity discussed by Kuroda, the fractional error introduced by anelasticity in such measurements of G is bounded by 0icons/Journals/Common/le" ALT="le" ALIGN="TOP"/>icons/Journals/Common/delta" ALT="delta" ALIGN="TOP"/> G/Gicons/Journals/Common/le" ALT="le" ALIGN="TOP"/> 1/2 Q-1, where Q is the torsional oscillation quality factor of the pendulum. We report detailed studies of anelasticity in candidate fibre materials at low temperature, concluding that anelastic behaviour should not limit our G measurement at a level of a few ppm.

Newman, R. D.; Bantel, M. K.

1999-06-01

137

Nonlinear electrodynamics in 3D gravity with torsion  

SciTech Connect

We study exact solutions of nonlinear electrodynamics coupled to three-dimensional gravity with torsion. We show that in any static and spherically symmetric configuration, at least one component of the electromagnetic field has to vanish. In the electric sector of the theory, we construct an exact solution, characterized by the azimuthal electric field. When the electromagnetic action is modified by a topological mass term, we find two types of the self-dual solutions.

Blagojevic, M.; Cvetkovic, B.; Miskovic, O. [Institute of Physics, University of Belgrade, P. O. Box 57, 11001 Belgrade (Serbia); Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile)

2009-07-15

138

External and internal coupling effects of rotor's bending and torsional vibrations under unbalances  

NASA Astrophysics Data System (ADS)

External and internal bending-torsion coupling effects of a rotor system with comprehensive unbalances are studied by analytical analysis and numerical simulations. Based on Lagrangian approach, a full-degree-of-freedom dynamic model of a Jeffcott rotor is developed. The harmonic balance method and the Floquet theory are combined to analyze the stability of the system equations. Numerical simulations are conducted to observe the bending-torsion coupling effects. In the formulation of rotordynamic model, two bending-torsion coupling patterns, external coupling and internal coupling, are suggested. By analytical analysis, it is concluded that the periodic solution of the system is asymptotically stable. From numerical simulations, three bending-torsion coupling effects are observed in three cases. Under static unbalance, synchronous torsional response is observed, which is the result of external coupling under unbalanced force. Under dynamic unbalance, two-time synchronous frequency torsional response is observed, which is the result of internal coupling under unbalanced moment. Under comprehensive unbalance, synchronous and two-time synchronous frequency torsional components are observed, which are the results of both external and internal couplings under unbalanced force and moment. These observations agree with the analytical analysis. It is believed that these observed phenomena should make sense in the dynamical design and fault diagnostics of a rotor system.

Yuan, Zhenwei; Chu, Fulei; Lin, Yanli

2007-01-01

139

Re-torsion of the ovaries.  

PubMed

The increasing use of de-torsion of the ovaries may result in re-torsion. This review addresses risk of re-torsion and describes preventive strategies to avoid re-torsion in pre-menarcheal girls, and fertile and pregnant women. We clinically reviewed PubMed, Embase, Trip and Cochrane databases. The main outcome measures were re-torsion and viability of ovary with fixation measures. A total of 38 publications including 71 girls, 363 fertile women, and 69 pregnant women were found to be relevant. All studies were case reports or case series, sometimes with non-randomized controls. The studies show considerable heterogeneity in design, population, management and outcome. Only four studies included more than 50 cases. In pregnancy the risk of re-torsion was as high as 19.5-37.5%; among fertile women it was 28.6%. Most articles concluded that fixation of the ovaries to the pelvic sidewall or plication of the ovarian ligament after torsion may prevent re-torsion. In one case a girl experienced re-torsion after ovariopexy. Based on observational studies it seems that de-torsion and fixation of the ovary is a safe procedure that usually ensures maintenance of ovarian function and reduces the risk of recurrence, especially when there are no ovarian cysts or adnexal masses. PMID:25412114

Hyttel, Trine E W; Bak, Geske S; Larsen, Solveig B; Løkkegaard, Ellen C L

2015-03-01

140

Determination of diesel engine cylinder gas torques from speed fluctuations with a high-fidelity crankshaft torsional model  

Microsoft Academic Search

An experimental investigation was conducted to develop a method of predicting cylinder indicated torques in a reciprocating engine by measurement of crankshaft angular velocity fluctuations. Cylinder indicated pressures were measured for all three cylinders of a two-stroke Diesel engine with pressure transducers. Time-resolved angular position was measured at the crankshaft front and at the flywheel. A six degree-of-freedom torsional crankshaft

1998-01-01

141

Medial femoral torsion and osteoarthritis.  

PubMed

We investigated the hypothesis that medial femoral torsion is a predisposing factor to osteoarthritis of the hip. Anteversion was measured by biplane radiography in 44 hips (32 patients) with idiopathic osteoarthritis of the hip and a control group of 98 normal hips (49 adults). The mean and range of anteversion measures were similar in both groups. The mean was 22 degrees for osteoarthritic hips (range 3 degrees-49 degrees) and 19 degrees for normal controls (range -2 degrees-49 degrees). This difference was not significant. This study disagrees with others that propose an association between increased anterversion and osteoarthritis of the hip. Prophylactic operative correction of femoral torsion for osteoarthritis is not recommended. PMID:3049668

Hubbard, D D; Staheli, L T; Chew, D E; Mosca, V S

1988-01-01

142

Torsional Micromirrors with Lateral Actuators  

Microsoft Academic Search

We report the first implementation of laterally actuated high aspect ratio torsionally suspended micromirrors. In-plane actuation is transformed into out-of- plane motion and rotation, enabling monolithic integration of a wide variety of SOI-MEMS sensors, actuators and micromirrors. The new actuation methodology features highly controllable and agile micromirror devices for optical communications. Two types of device structures integrated with comb-drive actuators

Veljko Milanovic; Matthew Last; Kristofer S. J. Pister

2001-01-01

143

Massive torsion modes from Adler-Bell-Jackiw and scaling anomalies  

E-print Network

Regularization of quantum field theories introduces a mass scale which breaks axial rotational and scaling invariances. We demonstrate from first principles that axial torsion and torsion trace modes have non-transverse vacuum polarization tensors, and become massive as a result. The underlying reasons are similar to those responsible for the Adler-Bell-Jackiw (ABJ) and scaling anomalies. Since these are the only torsion components that can couple minimally to spin 1/2 particles, the anomalous generation of masses for these modes, naturally of the order of the regulator scale, may help to explain why torsion and its associated effects, including CPT violation in chiral gravity, have so far escaped detection. As a simpler manifestation of the reasons underpinning the ABJ anomaly than triangle diagrams, the vacuum polarization demonstration is also pedagogically useful.

Lay Nam Chang; Chopin Soo

2001-04-20

144

Coupled lateral-torsional-axial vibrations of a helical gear-rotor-bearing system  

NASA Astrophysics Data System (ADS)

Considering the axial and radial loads, a mathematical model of angular contact ball bearing is deduced with Hertz contact theory. With the coupling effects of lateral, torsional and axial vibrations taken into account, a lumped-parameter nonlinear dynamic model of helical gearrotor-bearing system (HGRBS) is established to obtain the transmission system dynamic response to the changes of different parameters. The vibration differential equations of the drive system are derived through the Lagrange equation, which considers the kinetic and potential energies, the dissipative function and the internal/external excitation. Based on the Runge-Kutta numerical method, the dynamics of the HGRBS is investigated, which describes vibration properties of HGRBS more comprehensively. The results show that the vibration amplitudes have obvious fluctuation, and the frequency multiplication and random frequency components become increasingly obvious with changing rotational speed and eccentricity at gear and bearing positions. Axial vibration of the HGRBS also has some fluctuations. The bearing has self-variable stiffness frequency, which should be avoided in engineering design. In addition, the bearing clearance needs little attention due to its slightly discernible effect on vibration response. It is suggested that a careful examination should be made in modelling the nonlinear dynamic behavior of a helical gear-rotor-bearing system.

Li, Chao-Feng; Zhou, Shi-Hua; Liu, Jie; Wen, Bang-Chun

2014-10-01

145

Premotor neurons encode torsional eye velocity during smooth-pursuit eye movements  

NASA Technical Reports Server (NTRS)

Responses to horizontal and vertical ocular pursuit and head and body rotation in multiple planes were recorded in eye movement-sensitive neurons in the rostral vestibular nuclei (VN) of two rhesus monkeys. When tested during pursuit through primary eye position, the majority of the cells preferred either horizontal or vertical target motion. During pursuit of targets that moved horizontally at different vertical eccentricities or vertically at different horizontal eccentricities, eye angular velocity has been shown to include a torsional component the amplitude of which is proportional to half the gaze angle ("half-angle rule" of Listing's law). Approximately half of the neurons, the majority of which were characterized as "vertical" during pursuit through primary position, exhibited significant changes in their response gain and/or phase as a function of gaze eccentricity during pursuit, as if they were also sensitive to torsional eye velocity. Multiple linear regression analysis revealed a significant contribution of torsional eye movement sensitivity to the responsiveness of the cells. These findings suggest that many VN neurons encode three-dimensional angular velocity, rather than the two-dimensional derivative of eye position, during smooth-pursuit eye movements. Although no clear clustering of pursuit preferred-direction vectors along the semicircular canal axes was observed, the sensitivity of VN neurons to torsional eye movements might reflect a preservation of similar premotor coding of visual and vestibular-driven slow eye movements for both lateral-eyed and foveate species.

Angelaki, Dora E.; Dickman, J. David

2003-01-01

146

Brane World black holes in Teleparallel Theory Equivalent to General Relativity and their Killing vectors, Energy, Momentum and Angular-Momentum  

E-print Network

The energy-momentum tensor, which is coordinate independent, is used to calculate energy, momentum and angular-momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space-time their energies are different. Therefore, a regularized expression of the gravitational energy-momentum tensor of the teleparallel equivalent of general relativity, (TEGR), is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy-momentum is used to investigate the energy within the external event horizon. The components of angular-momentum associated with these space-times are calculated. In spite that we use a static space-times, we get a non-zero component of angular-momentum! Therefore, we derive the killing vectors associated with these space-times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.

Gamal G. L. Nashed

2009-10-27

147

Brane World black holes in Teleparallel Theory Equivalent to General Relativity and their Killing vectors, Energy, Momentum and Angular-Momentum  

E-print Network

The energy-momentum tensor, which is coordinate independent, is used to calculate energy, momentum and angular-momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space-time their energies are different. Therefore, a regularized expression of the gravitational energy-momentum tensor of the teleparallel equivalent of general relativity, (TEGR), is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy-momentum is used to investigate the energy within the external event horizon. The components of angular-momentum associated with these space-times are calculated. In spite that we use a static space-times, we get a non-zero component of angular-momentum! Therefore, we derive the killing vectors associated with these space-times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.

Nashed, Gamal G L

2009-01-01

148

A first-order secular theory for the post-Newtonian two-body problem with spin - II. A complete solution for the angular coordinates in the restricted case  

NASA Astrophysics Data System (ADS)

Building on the results of a previous paper, we compute for the first time a full first-order perturbative solution for the angular coordinates in the restricted post-Newtonian two-body problem with spin. The analytical integration of the angular coordinates, based on the theory of the Weierstrassian functions, allows us to investigate thoroughly the spin-orbit and spin-spin interactions, and to derive several new results. The application of our solution to a selection of idealized physical systems of interest reveals a rich variety of dynamical behaviours driven by purely relativistic effects. In particular, we highlight a new relativistic nutational motion resulting from the combined spin-orbit and spin-spin interactions.

Biscani, Francesco; Carloni, Sante

2015-01-01

149

The millimeter and submillimeter laboratory spectrum of methyl formate in its ground symmetric torsional state  

NASA Technical Reports Server (NTRS)

Over 200 rotational lines of methyl formate in its ground (v sub t = 0), symmetric (A) torsional state have been measured in the frequency range 140-550 GHz. Analysis of these and lower frequency transitions permits accurate prediction (below 0.1 MHz) of over 10,000 transitions at frequencies below 600 GHz with angular momentum J lower than 50. The measured spectral lines have permitted identification of over 100 new methyl formate lines in Orion.

Plummer, G. M.; Herbst, E.; De Lucia, F.; Blake, G. A.

1984-01-01

150

Gauge invariant coupling of fields to torsion: A string inspired model  

NASA Astrophysics Data System (ADS)

In a consistent heterotic string theory, the Kalb-Ramond field, which is the source of space-time torsion, is augmented by Yang-Mills and gravitational Chern-Simons terms. When compactified to 4 dimensions and in the field theory limit, such additional terms give rise to interactions with interesting astrophysical predictions like rotation of plane of polarization for electromagnetic and gravitational waves. On the other hand, if one is also interested in coupling 2- or 3-form (Abelian or non-Abelian) gauge fields to torsion, one needs another class of interaction. In this paper, we shall study this interaction and offer some astrophysical and cosmological predictions. We explicitly calculate the Coleman-Weinberg potential for this theory. We also comment on the possibility of such terms in loop quantum gravity where, if the Barbero-Immirzi parameter is promoted to a field, acts as a source for torsion.

Bhattacharjee, Srijit; Chatterjee, Ayan

2011-05-01

151

Gauge invariant coupling of fields to torsion: A string inspired model  

SciTech Connect

In a consistent heterotic string theory, the Kalb-Ramond field, which is the source of space-time torsion, is augmented by Yang-Mills and gravitational Chern-Simons terms. When compactified to 4 dimensions and in the field theory limit, such additional terms give rise to interactions with interesting astrophysical predictions like rotation of plane of polarization for electromagnetic and gravitational waves. On the other hand, if one is also interested in coupling 2- or 3-form (Abelian or non-Abelian) gauge fields to torsion, one needs another class of interaction. In this paper, we shall study this interaction and offer some astrophysical and cosmological predictions. We explicitly calculate the Coleman-Weinberg potential for this theory. We also comment on the possibility of such terms in loop quantum gravity where, if the Barbero-Immirzi parameter is promoted to a field, acts as a source for torsion.

Bhattacharjee, Srijit; Chatterjee, Ayan [Theory Group, Saha Institute of Nuclear Physics, Kolkata 700064 (India); The Institute of Mathematical Sciences, CIT Campus, Taramani, Chennai-600113 (India)

2011-05-15

152

The torsional excitation of variable intertia effects in a reciprocating engine  

NASA Astrophysics Data System (ADS)

Reciprocating machinery has a cyclically varying inertia function and as a consequence exhibits non-linear frequency coupling between rotational speed and the system's torsional natural frequencies. Although in theory the type of frequency coupling which takes place has been well explored, it has been difficult to investigate the effect experimentally and hence to verify the theory. It is the purpose of this paper to present the findings of a recent experimental investigation, which uses an a.c. servo motor to excite torsionally variable inertia effects in a single cylinder engine. The measurements confirm the theory. As anticipated, frequency coupling was observed experimentally as modulation of torsional resonant frequencies by the rotating frequencies and their harmonics. This effect was reciprocal, with excitation of natural frequencies causing secondary resonance sidebands, and excitation at secondary resonance sidebands generating a significant resonant response.

Drew, S. J.; Hesterman, D. C.; Stone, B. J.

1999-01-01

153

Area-angular momentum-charge inequality for stable marginally outer trapped surfaces in 4D Einstein-Maxwell-dilaton theory  

NASA Astrophysics Data System (ADS)

We derive inequalities between the area, the angular momentum, and the charges for axisymmetric closed outermost stably marginally outer trapped surfaces, embedded in dynamical and, in general, nonaxisymmetric spacetimes satisfying the Einstein-Maxwell-dilaton-matter equations. In proving the inequalities, we assume that the dilaton potential is non-negative and that the matter energy-momentum tensor satisfies the dominant energy condition.

Yazadjiev, Stoytcho

2013-01-01

154

Calculation of the dielectric and Kerr constant angular correlation parameters  

Microsoft Academic Search

The angular correlation parameters GL involved in the dielectric and Kerr constants are written as averages over the angular pair correlation function. A perturbation theory for these parameters is developed, based on the expansion of Gubbins and Gray for the angular pair correlation function. Numerical calculations are presented showing the influence of polar and quadrupolar forces on these parameters.

C. G. Gray; K. E. Gubbins

1975-01-01

155

Interpretation of strains in torsion shear tests  

Microsoft Academic Search

The normal and shear strains obtained in torsion shear tests may be interpreted in two different ways to gain insight into (1) the type of plastic potential to be employed in hardening plasticity stress–strain models, and (2) the coincidence in physical space of the plastic strain increment direction with the stress direction during principal stress rotation. Thirty-four drained torsion shear

Poul V. Lade; Jungman Nam; Won Pyo Hong

2009-01-01

156

Optically probing torsional superelasticity in spider silks  

NASA Astrophysics Data System (ADS)

We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 102-3 rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

2013-11-01

157

Optically probing torsional superelasticity in spider silks  

SciTech Connect

We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2?3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P. [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)] [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)

2013-11-11

158

Torsion of Noncircular Composite Cylinders  

NASA Technical Reports Server (NTRS)

The paper presents a brief overview of the predicted deformation and failure characteristics of noncircular composite cylinders subjected to torsion. Using a numerical analysis, elliptical cylinders with a minor-to-major diameter ratio of 0.7 are considered. Counterpart circular cylinders with the same circumference as the elliptical cylinders are included for comparison. The cylinders are constructed of a medium-modulus graphite-epoxy material in a quasi-isotropic lay-up. Imperfections generated from the buckling mode shapes are included in the initial cross-sectional geometry of the cylinders. Deformations until first fiber failure, as predicted using the maximum stress failure criterion and a material degradation scheme, are presented. For increasing levels of torsion, the deformations of the elliptical cylinders, in the form of wrinkling of the cylinder wall, occur primarily in the flatter regions of the cross section. By comparison the wrinkling deformations of the circular cylinders are more uniformly distributed around the circumference. Differences in the initial failure and damage progression and the overall torque vs. twist relationship between the elliptical and circular cylinders are presented. Despite differences in the response as the cylinders are being loaded, at first fiber failure the torque and twist for the elliptical and circular cylinders nearly coincide.

Rouse, Marshall; Hyer, Michael W.; Haynie, Waddy T.

2005-01-01

159

September 12, 2007 THE ISOMORPHISM PROBLEM FOR TORSION-FREE  

E-print Network

September 12, 2007 THE ISOMORPHISM PROBLEM FOR TORSION-FREE ABELIAN GROUPS IS ANALYTIC COMPLETE. ROD DOWNEY AND ANTONIO MONTALB´AN Abstract. We prove that the isomorphism problem for torsion-free for countable torsion-free Abelian groups. The question we ask is, given two countable torsion-free Abelian

160

Torsion Balance Search for Lorentz-invariance, Dark  

E-print Network

Torsion Balance Search for Lorentz-invariance, Dark Energy and Dark Matter Claire Cramer AAPT of unpolarized matter another particle's spin #12;Torsion balances Coulomb's torsion balance: A high precision-plated · magnetically shielded · 4 mirrors 2.6 cm #12;#12;The torsion balance apparatus feet pendulum magnetic shielding

161

Propagation of torsional waves within the Earth's outer core  

NASA Astrophysics Data System (ADS)

The changes in the Length of Day on decadal timescale arise because of changes of the geostrophic circulation within the Earth's core, which are governed by an equation of the Alfvèn wave type. This equation describes directly the transport of angular momentum ( d? (s)=4pi s3sqrt{a2-s2}? g(s)ds ) within the Earth's core (( a ) is the core radius, ( s ) is the distance to the rotation axis and ( ? g(s) ) is the geostrophic angular velocity). As the waves are propagated towards ( s=a ), geostrophic velocity is strongly amplified. In the other direction, the waves are rapidly dissipated as they encounter the Earth's inner core because of the very efficient magnetic coupling between the liquid and solid parts of the core. We investigate whether these two phenomena are associated with rapid changes in the Earth's magnetic field ({}``jerks{}''). Before his death, Steve Zatman had indeed noticed, together with Bloxham and Dumberry, that we may understand why the magnetic jerks are observed in only a subset of the magnetic observatories if they are caused by torsional waves within the Earth's core. Earlier studies have assumed that the waves are monochromatic. We have preferred to solve the propagation of torsional Alfvèn waves as an initial value problem because they are probably highly damped, as found by Zatman and his co-authors. Finally, we compare magnetic and viscous coupling at the core-mantle boundary taking into account results from a recent spin-up experiment by Brito and colleagues.

Jault, D.; Legaut, G.

2003-04-01

162

Magnetic Torsional Oscillations in Magnetars  

SciTech Connect

We investigate torsional Alfven oscillations of relativistic stars with a global dipole magnetic field, via 2D numerical simulations. We find that a) there exist two families of quasi-periodic oscillations (QPOs) with harmonics at integer multiples of the fundamental frequency, b) the QPOs are long-lived, c) for the chosen form of dipolar magnetic field, the frequency ratio of the lower to upper fundamental QPOs is about 0.6, independent of the equilibrium model or of the strength of the magnetic field, and d) within a representative sample of EOS and of various magnetar masses, the Alfven QPO frequencies are given by accurate empirical relations that depend only on the compactness of the star and on the magnetic field strength. Compared to the observational frequencies, we also obtain an upper limit on the strength of magnetic field of SGR 1806-20 (if is dominated by a dipolar component) between {approx}3 and 7x10{sup 15} Gauss.

Sotani, Hajime [Theoretical Astrophysics, University of Tuebingen, 72076, Tuebingen (Germany); Kokkotas, Kostas D. [Theoretical Astrophysics, University of Tuebingen, 72076, Tuebingen (Germany); Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Stergioulas, Nikolaos [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)

2009-05-01

163

Torsional oscillations of strange stars  

NASA Astrophysics Data System (ADS)

Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange collapsed quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of 1045 erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.

Mannarelli, Massimo

2014-11-01

164

Modification of gravity due to torsion  

SciTech Connect

Modifications of general relativity have been considered as one of the possible ways of addressing some of the outstanding problems related to the large scale gravitational physics. In this contribution we review some of the recent results which are due to the inclusion of dynamical torsion. More specifically we shall discuss the propagation of massive spin-2 particles in flat and curved space times. We shall show that, contrary to what is generally believed, spinning matter is not the sole source of torsion field. A symmetric energy momentum tensor can also couple to torsion degrees of freedom. The massive and massless spin-2 particles mix giving rise to an infrared modification of gravity.

Nair, V. P. [Physics Department, City College of the CUNY, New York, NY 10031 (United States); Nikiforova, V. [Physics Department, Mascow State University Moscow (Russian Federation); Randjbar-Daemi, S. [The Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Rubakov, V. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation)

2010-01-01

165

Torsional irregularity in multi-story structures  

NASA Astrophysics Data System (ADS)

The purpose of this study is first to determine the conditions for excessive torsional irregularity and then to discuss the validity of code provisions. A parametric investigation is performed on six groups of typical structures with varying shear wall positions, story, and axis numbers. It is found that torsional irregularity coefficients increase as the story numbers decrease, i.e., maximum irregularity coefficients occur for single-story structures. They reach maximum values when the asymmetrical shear walls are placed as close as possible to the centers of mass. However, the results obtained for floor rotations are quite contradictory. A new provisional definition for torsional irregularity coefficient based on floor rotations is proposed.

Özmen, Günay; Girgin, Konuralp; Durgun, Yavuz

2014-12-01

166

Inevitable inflation in Einstein-Cartan theory with improved energy-momentum tensor with spin  

NASA Technical Reports Server (NTRS)

Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic, (Bianchi Type-1) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley improved energy momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density. Shear is not effective in preventing inflation in the ECRS model. The relation between fluid vorticity, torsion, reference axis rotation, and shear ellipsoid precession shows through clearly.

Fennelly, A. J.; Bradas, James C.; Smalley, Larry L.

1988-01-01

167

Adnexal torsion -- a multimodality imaging review.  

PubMed

Adnexal torsion is a gynaecological surgical emergency as prompt restoration of ovarian blood flow may prevent permanent irreversible damage. Patients frequently present with non-specific symptoms and signs and therefore adnexal torsion is often an unexpected radiological diagnosis. Although ultrasound is the initial imaging technique of choice in suspected adnexal torsion, many patients undergo computed tomography (CT) or magnetic resonance imaging (MRI) either as a first-line test following non-specific presentation, or as a confirmatory test following equivocal ultrasound findings. Using multiple techniques, this review illustrates the wide variety of imaging features observed in adnexal torsion enabling a confident diagnosis that may result in a more favourable surgical outcome. PMID:22137723

Wilkinson, C; Sanderson, A

2012-05-01

168

Dirac-harmonic maps with torsion  

E-print Network

We study Dirac-harmonic maps from surfaces to manifolds with torsion, which is motivated from the superstring action considered in theoretical physics. We discuss analytic and geometric properties of such maps and outline an existence result for uncoupled solutions.

Volker Branding

2014-05-20

169

Dark Energy: Is It of Torsion Origin?  

E-print Network

{\\it "Dark Energy"} is a term recently used to interpret supernovae type Ia observation. In the present work we give two arguments on a possible relation between dark energy and torsion of space-time.

M. I. Wanas

2010-06-10

170

Transcription-generated torsional stress destabilizes nucleosomes  

PubMed Central

As RNA Polymerase II (Pol II) transcribes a gene, it encounters an array of well-ordered nucleosomes. How it traverses through this array in vivo remains unresolved. One model proposes that torsional stress generated during transcription destabilizes nucleosomes ahead of Pol II. Here, we describe a method for high resolution mapping of underwound DNA using next-generation sequencing, and show that torsion is correlated with gene expression in Drosophila melanogaster cells. Accumulation of torsional stress, through topoisomerase inhibition, results in increased. Pol II at transcription start sites. Whereas Topo I inhibition results in increased nascent RNA transcripts, Topo II inhibition shows little change. Despite the different effects on Pol II elongation, topoisomerase inhibition results in increased nucleosome turnover and salt solubility within gene bodies, suggesting that the elongation-independent effects of torsional stress on nucleosome dynamics contributes to the destabilization of nucleosomes. PMID:24317489

Teves, Sheila S.; Henikoff, Steven

2013-01-01

171

Angular shear plate  

Microsoft Academic Search

One or more disc-shaped angular shear plates each include a region thereon having a thickness that varies with a nonlinear function. For the case of two such shear plates, they are positioned in a facing relationship and rotated relative to each other. Light passing through the variable thickness regions in the angular plates is refracted. By properly timing the relative

Mitchell C. Ruda; Alan W. Greynolds; Tilman W. Stuhlinger

2009-01-01

172

Angular Acceleration without Torque?  

ERIC Educational Resources Information Center

Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

Kaufman, Richard D.

2012-01-01

173

Infrared and Millimeter-Wave Study of the Four Lowest Torsional States of CH(3)CF(3).  

PubMed

An investigation of the torsion-rotation Hamiltonian of CH(3)CF(3) in the ground vibrational state has been carried out using infrared and mm-wave spectroscopy. With infrared Fourier transform spectroscopy, the weak, torsional overtone (v(6) = 2 <-- 0) has been studied leading to the measurement of 382 frequencies between 405 and 440 cm(-1) at a resolution of 0.005 cm(-1). Torsional splittings on the order of 0.03 cm(-1) were observed. With mm-wave methods, a total of 669 rotational transitions between 50 and 360 GHz have been measured at Doppler-limited resolution in the four lowest torsional states v(6) = 0, 1, 2, 3. The experimental uncertainty attained for an isolated line was better than 10 kHz below 150 GHz, and somewhat larger at higher frequencies. For v(6) = 3, torsional splittings as large as 8.7 MHz were observed. The global data set consisted of the current frequency determinations and the 443 measurements with molecular beam, microwave, and mm-wave methods analyzed by I. Ozier, J. Schroderus, S.-X. Wang, G. A. McRae, M. C. L. Gerry, B. Vogelsanger, and A. Bauder [J. Mol. Spectrosc. 190, 324-340 (1998)]. The observation of mm-wave R-branch transitions for v(6) = 1 led to a change in the J-assignment of the forbidden (Deltak = +/-3) transitions reported earlier for this torsional state. A good fit was obtained by varying 24 parameters in a Hamiltonian that represented both the torsional effects and the sextic splittings. In the earlier work, the large reduced barrier height led to high correlations among several of the torsional distortion constants. With the current measurements, many of these correlations are substantially reduced. Improved effective values were determined for the height V(3) of the hindering barrier and the first-order correction V(6) in the Fourier expansion of the potential function. The dipole function which characterizes the transition moment of the torsional overtone (v(6) = 2 <-- 0) can be written as the product of a single effective dipole constant µ(T)(0,eff) and the appropriate off-diagonal matrix element of (1 - cos 3alpha)/2, where alpha is the torsional angle. From an intensity analysis of the infrared spectrum, it has been determined that |µ(T)(0,eff)| = 85.3(62) mD. A novel approach based on a simple regrouping of angular momentum operators is introduced for decoupling the torsional and rotational degrees of freedom. Copyright 2001 Academic Press. PMID:11148119

Wang; Schroderus; Ozier; Moazzen-Ahmadi; McKellar; Ilyushyn; Alekseev; Katrich; Dyubko

2001-01-01

174

MSTor version 2013: A new version of the computer code for the multi-structural torsional anharmonicity, now with a coupled torsional potential  

NASA Astrophysics Data System (ADS)

We present an improved version of the MSTor program package, which calculates partition functions and thermodynamic functions of complex molecules involving multiple torsions; the method is based on either a coupled torsional potential or an uncoupled torsional potential. The program can also carry out calculations in the multiple-structure local harmonic approximation. The program package also includes seven utility codes that can be used as stand-alone programs to calculate reduced moment of inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes for torsional subdomains defined by Voronoi tessellation of the conformational subspace, to generate template input files for the MSTor calculation and Voronoi calculation, and to calculate one-dimensional torsional partition functions using the torsional eigenvalue summation method. Restrictions: There is no limit on the number of torsions that can be included in either the Voronoi calculation or the full MS-T calculation. In practice, the range of problems that can be addressed with the present method consists of all multitorsional problems for which one can afford to calculate all the conformational structures and their frequencies. Unusual features: The method can be applied to transition states as well as stable molecules. The program package also includes the hull program for the calculation of Voronoi volumes, the symmetry program for determining point group symmetry of a molecule, and seven utility codes that can be used as stand-alone programs to calculate reduced moment-of-inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes of the torsional subdomains defined by Voronoi tessellation of the conformational subspace, to generate template input files, and to calculate one-dimensional torsional partition functions using the torsional eigenvalue summation method. Additional comments: The program package includes a manual, installation script, and input and output files for a test suite. Running time: There are 26 test runs. The running time of the test runs on a single processor of the Itasca computer is less than 2 s. References: [1] MS-T(C) method: Quantum Thermochemistry: Multi-Structural Method with Torsional Anharmonicity Based on a Coupled Torsional Potential, J. Zheng and D.G. Truhlar, Journal of Chemical Theory and Computation 9 (2013) 1356-1367, DOI: http://dx.doi.org/10.1021/ct3010722. [2] MS-T(U) method: Practical Methods for Including Torsional Anharmonicity in Thermochemical Calculations of Complex Molecules: The Internal-Coordinate Multi-Structural Approximation, J. Zheng, T. Yu, E. Papajak, I, M. Alecu, S.L. Mielke, and D.G. Truhlar, Physical Chemistry Chemical Physics 13 (2011) 10885-10907.

Zheng, Jingjing; Meana-Pañeda, Rubén; Truhlar, Donald G.

2013-08-01

175

Torsion Field Effect and Zero-Point Energy in Electrical Discharge Systems  

Microsoft Academic Search

Highly localized nuclear activation in electrochemical systems and other electrical discharge processes have been observed by many laboratories in world. There is an attempt to explain such anomalous phenomena by using torsion field theory and axion model in this report. Anisotopic behaviours of radiation products, burst charaster, \\

Xiong-wei Wen; Li-jun Han

2004-01-01

176

Stepping-Motor Drive Suppresses Torsional Oscillation  

NASA Technical Reports Server (NTRS)

Excitation in stepping-motor drive differs from conventional excitation in that each step is divided into two equal smaller steps separated by small interval, tau. Interval chosen to equal half period of torsional oscillation, so second step excitation equal in amplitude but opposite in phase to first step excitation. Thus, although first step unavoidably excites torsional oscillation, second step deexcites oscillation at end of first half cycle.

Bhat, Mahabaleshwar K. P.

1995-01-01

177

Flow in a torsionally oscillating filled cylinder  

NASA Technical Reports Server (NTRS)

The flow of a liquid in a completely filled cylinder undergoing torsional oscillations about its longitudinal symmetry axis was studied analytically and experimentally. The objective of the studies was to determine the efficacy of the torsional oscillations in mixing the confined liquid. Flow was found to be confined primarily to toroidal cells at the ends of the cylinder. Cell thickness was about equal to the cylinder radius. The use of baffles at the end walls was shown to enhance the mixing process.

Schafer, C. F.

1983-01-01

178

Coupled modes of the torsion pendulum  

NASA Astrophysics Data System (ADS)

The coupling of the swing modes of a torsion pendulum to the torsional mode has been solved analytically. Our solution provides a clear explanation of why a magnetic damper is effective in suppressing unwanted modes in most gravitational experiments. The analytic solution also shows that the amplitude of the mode coupling is greatest at the lowest frequencies. This explains why mode coupling at the lowest frequency is all that is observed in the experiments reported here.

Fan, Xiang-Dong; Liu, Qi; Liu, Lin-Xia; Milyukov, Vadim; Luo, Jun

2008-01-01

179

Spinflation with angular potentials  

NASA Astrophysics Data System (ADS)

We investigate in detail the cosmological consequences of realistic angular dependent potentials in the brane inflation scenario. Embedding a warped throat into a compact Calabi-Yau space with all moduli stabilized breaks the no-scale structure and induces angular dependence in the potential of the probe D3-brane. We solve the equations of motion from the DBI action in the warped deformed conifold including linearized perturbations around the imaginary self-dual solution. Our numerical solutions show that angular dependence is a next to leading order correction to the dominant radial motion of the brane, however, just as angular motion typically increases the amount of inflation (spin-flation), having additional angular dependence also increases the amount of inflation. We also derive an analytic approximation for the number of e-foldings along the DBI trajectory in terms of the compactification parameters.

Gregory, Ruth; Kaviani, Dariush

2012-01-01

180

Analytic torsion for twisted de Rham complexes  

E-print Network

We define analytic torsion for the twisted de Rham complex, consisting of the spaces of differential forms on a compact oriented Riemannian manifold X valued in a flat vector bundle E, with a differential given by a flat connection on E plus an odd-degree closed differential form H on X. The difficulty lies in the fact that the twisted de Rham complex is only Z_2-graded, and so the definition of analytic torsion in this case uses pseudo-differential operators and residue traces. We show that when dim X is odd, then the twisted analytic torsion is independent of the choice of metrics on X and E and of the representative H in the cohomology class of H. We define twisted analytic torsion in the context of generalized geometry and show that when H is a 3-form, the deformation H -> H - dB, where B is a 2-form on X, is equivalent to deforming a usual metric g to a generalized metric (g,B). We establish some basic functorial properties. When H is a top-degree form, we compute the torsion, define its simplicial counterpart and prove an analogue of the Cheeger-Muller Theorem. We also study the relationship of the analytic torsion for T-dual circle bundles with integral 3-form fluxes.

Varghese Mathai; Siye Wu

2011-03-31

181

The Torsional Fundamental Band of Methylformate  

NASA Astrophysics Data System (ADS)

Methylformate (HCOOCH_3) is one of the most important molecules in astrophysics, first observed in 1975. The rotational structure of its ground and first excited torsional states are well known from millimeter wave measurements. However, some of the torsional parameters are still not precisely determined because information on the torsional vibrational frequency v_t = 1-0 is missing. To overcome that problem, the far infrared spectrum of HCOOCH_3 was recorded with a 150 m optical path in a White cell and a Bruker IFS 125 HR Fourier transform spectrometer at the AILES beamline of the synchrotron SOLEIL facility. The analysis of the very weak fundamental torsional band v_t = 1-0 observed around 130 Cm-1 was carried out. It led to the first precise determination of the torsional barrier height and the dipole moment induced by the torsional motion. This work is partly supported by the "Programme National de Physico-Chimie du Milieu Interstellaire" (PCMI-CNRS) and by the contract ANR-BLAN-08-0054. R.D. Brown, J.G. Crofts, P.D. Godfrey, F.F. Gardner, B.J. Robinson, J.B. Whiteoak, Astrophys. J. 197 (1975) L29-L31. See V. Ilyushin, A. Kryvda, E. Alekseev, J. Mol. Spectrosc. 255 (2009) 32-38, and references therein.

Tudorie, M.; Ilyushin, V.; Vander Auwera, J.; Pirali, O.; Roy, P.; Huet, T. R.

2011-06-01

182

X-ray diffraction study on the microstructure of a MgZnY alloy consolidated by high-pressure torsion  

E-print Network

plastic deformation (SPD) techniques, such as cyclic extrusion and compression (CEC) [11], equal-channel angular pressing (ECAP) [12­14] or high-pres- sure torsion (HPT) [15­19]. Among the various SPD methods and extrusion sys- tems applied recently for the consolidation of Mg-alloys [25]. In the present study, a gas

Gubicza, Jenõ

183

Cross-shaped torsional spring  

DOEpatents

The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section. 30 figs.

Williamson, M.M.; Pratt, G.A.

1999-06-08

184

Cross-shaped torsional spring  

DOEpatents

The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section.

Williamson, Matthew M. (Boston, MA); Pratt, Gill A. (Lexington, MA)

1999-06-08

185

Torsional boundary layer effects in shells of revolution undergoing large axisymmetric deformation  

NASA Astrophysics Data System (ADS)

Numerical and asymptotic solutions are developed to the equations governing large torsional, axisymmetric deformation of rubberlike shells of revolution. The shell equations include large-strain geometric and material nonlinearities, transverse shear deformation, transverse normal stress and strain, and torsion. Both analyses allow ready incorporation of different strain-energy density functions. In the asymptotic analysis, the interior solution corresponds to that of nonlinear membrane theory and contains a primary boundary layer. The edge-zone solution gives a secondary boundary layer that, for large strain, divides into a bending-twisting moment component and a torsional-membrane component. The boundary layer behavior is illustrated for a clamped neo-Hookean cylinder subjected to internal pressure and axial torque.

Su, F.-C.; Taber, L. A.

1992-01-01

186

Accurate torsional potentials for monohalo and fluorohalo keto-enolate compounds  

NASA Astrophysics Data System (ADS)

Accurate torsional potentials upon two rotatable carbon-carbon bonds for monohalo and fluorohalo keto-enolate compounds were constructed using CCSD(T)/CBS level of theory. Stable conformers of monohalo and fluorohalo keto-enolates can be determined from the steric repulsion between moieties around these carbon-carbon bonds. The repulsion between fluorine and halogen atoms is the strongest and stronger than that between oxygen and halogen, followed by that between oxygen and oxygen. The maximum of the torsional potentials corresponds to the conformation where both or one of the two rotatable bonds align perpendicular to the molecular plane, suggesting the strong double bond character between these two carbon-carbon bonds. Thus, the ?-bond conjugation and steric repulsion control the torsional potentials of monohalo and fluorohalo keto-enolate compounds.

Vongachariya, Arthit; Tantiwattanakul, Sutheera; Parasuk, Vudhichai

187

Renormalizability of the Dirac Equation in Torsion-Gravity with Non-Minimal Coupling  

E-print Network

We will consider the torsional completion of gravity for a background filled with Dirac matter fields, studying what happens when fermionic non-minimal coupling is taken into account: we will show that, although non-minimal couplings are usually disregarded because of their ill-defined behaviour in ultraviolet regimes, this is due to the fact that torsion is commonly neglected, whereas when torsion is not left aside, even non-minimal couplings behave properly. In detail, we will see that non-minimal coupling allows to renormalize the Dirac equation even when torsion is taken into consideration and that in some type of non-minimally coupled models parity-oddness might be present even in the gravitational sector. In addition, we will show that in the presence of the considered non-minimal coupling, torsion is able to evade cosmological singularities as it can happen in the minimal coupling case and in some other non--minimally coupled theory. In the course of the paper, we shall consider a specific interaction as prototype to study this fermionic non-minimal coupling, but we will try to present results that do not depend on the actual structure of the non-minimal couplings by investigating alternative types of interaction.

Luca Fabbri; Stefano Vignolo; Sante Carloni

2014-04-23

188

Analytical procedure for modelling recursively and wire by wire stranded ropes subjected to traction and torsion loads  

Microsoft Academic Search

The aim of this article is to introduce a new theoretical procedure for modelling wire ropes subjected simultaneously to tensile and torsional loads. The procedure is based upon the beam assumption and takes account wire by wire of the double helical wires on the basis of general thin rod theory developed by [Love, A., 1944. Mathematical Theory of Elasticity. Dover

H. Usabiaga; J. M. Pagalday

2008-01-01

189

Predicting Stellar Angular Sizes  

E-print Network

Our survey of long-baseline infrared and optical interferometry measurements is producing considerable numbers of directly determined stellar angular sizes. We use our sample of 124 high-precision (5\\%) angular stellar diameter values and correlate them with stellar magnitude values from the literature to produce empirical relations for main-sequence stars between observed apparent magnitudes, stellar colors, and angular sizes (surface brightness relations). We find a significant dependence on stellar metallicity for ($B-V$) colors. The scatter in the calculated relations is small ($\\sim$5\\%), which makes them a robust tool for the prediction of main-sequence stellar angular sizes based on photometry. We apply these relations via the calculation of the radius of the multiplanet host star GJ 667C.

von Braun, Kaspar; van Belle, Gerard T

2013-01-01

190

Optical Broadband Angular Selectivity  

E-print Network

Light selection based purely on the angle of propagation is a long-standing scientific challenge. In angularly selective systems, however, the transmission of light usually also depends on the light frequency. We tailored ...

Shen, Yichen

191

Metamaterial broadband angular selectivity  

E-print Network

We demonstrate how broadband angular selectivity can be achieved with stacks of one-dimensionally periodic photonic crystals, each consisting of alternating isotropic layers and effective anisotropic layers, where each ...

Shen, Yichen

192

Angular velocity discrimination  

NASA Technical Reports Server (NTRS)

Three experiments designed to investigate the ability of naive observers to discriminate rotational velocities of two simultaneously viewed objects are described. Rotations are constrained to occur about the x and y axes, resulting in linear two-dimensional image trajectories. The results indicate that observers can discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.

Kaiser, Mary K.

1990-01-01

193

Endodontic instruments after torsional failure: nanoindentation test.  

PubMed

This study aimed to evaluate effects of torsional loading on the mechanical properties of endodontic instruments using the nanoindentation technique. ProFile (PF; size 30, taper 04; Dentsply Maillefer, Switzerland) and stainless steel (SS; size 30, taper 02; Mani, Japan) instruments were subjected to torsional test. Nanoindentation was then performed adjacent to the edge of fracture (edge) and at the cutting part beside the shank (shank). Hardness and elastic modulus were measured under 100-mN force on 100 locations at each region, and compared to those obtained from the same regions on new instruments. It showed that PF and SS instruments failed at 559?±?67 and 596?±?73 rotation degrees and mean maximum torque of 0.90?±?0.07 and 0.99?±?0.05?N-cm, respectively. Hardness and elastic modulus ranged 4.8-6.7 and 118-339?GPa in SS, and 2.7-3.2 and 52-81?GPa in PF. Significant differences between torsion-fractured and new instruments in hardness and elastic modulus were detected in the SS system used. While in PF system, the edge region after torsional fracture had significantly lower hardness and elastic modulus compared to new instruments. The local hardness and modulus of elasticity of endodontic instruments adjacent to the fracture edge are significantly reduced by torsional loading. PMID:24610598

Jamleh, Ahmed; Sadr, Alireza; Nomura, Naoyuki; Ebihara, Arata; Yahata, Yoshio; Hanawa, Takao; Tagami, Junji; Suda, Hideaki

2014-01-01

194

Torsion-Mediated Interaction between Adjacent Genes  

PubMed Central

DNA torsional stress is generated by virtually all biomolecular processes involving the double helix, in particular transcription where a significant level of stress propagates over several kilobases. If another promoter is located in this range, this stress may strongly modify its opening properties, and hence facilitate or hinder its transcription. This mechanism implies that transcribed genes distant of a few kilobases are not independent, but coupled by torsional stress, an effect for which we propose the first quantitative and systematic model. In contrast to previously proposed mechanisms of transcriptional interference, the suggested coupling is not mediated by the transcription machineries, but results from the universal mechanical features of the double-helix. The model shows that the effect likely affects prokaryotes as well as eukaryotes, but with different consequences owing to their different basal levels of torsion. It also depends crucially on the relative orientation of the genes, enhancing the expression of eukaryotic divergent pairs while reducing that of prokaryotic convergent ones. To test the in vivo influence of the torsional coupling, we analyze the expression of isolated gene pairs in the Drosophila melanogaster genome. Their orientation and distance dependence is fully consistent with the model, suggesting that torsional gene coupling may constitute a widespread mechanism of (co)regulation in eukaryotes. PMID:25188032

Meyer, Sam; Beslon, Guillaume

2014-01-01

195

Angular distribution of turbulence in wave space  

NASA Technical Reports Server (NTRS)

An alternative to the one-point closure model for turbulence, the large eddy simulation (LES), together with its more exact relative, direct numerical simulation (DNS) are discussed. These methods are beginning to serve as partial substitutes for turbulence experiments. The eddy damped quasi-normal Markovian (EDQNM) theory is reviewed. Angular distribution of the converted data was examined in relationship to EDQNM.

Coleman, G.; Ferziger, J. H.; Bertoglio, J. P.

1987-01-01

196

Torsional optical spring effect in coupled nanobeam photonic crystal cavities.  

PubMed

Compared to probe-tuned optomechanical cavity systems, coupled cavity systems have the merit of having much stronger optomechanical interactions. However, to date, the torsional optomechanical effects of coupled cavities have rarely been investigated. In this Letter, we report a torsional optical spring effect in coupled nanobeam photonic crystal cavities. One of the cavities is suspended by a multi-degree-of-freedom spring mechanism that supports torsional vibration modes. The cavities' light field acts in reverse on the selected torsional mode, thus generating a torsional optical spring effect. The experimental results show that the third-order torsional mode of the spring mechanism is optically stiffened and a maximum frequency increase of 77.1 Hz is obtained. The device provides a novel configuration for the optomechanical design of a new degree of freedom (torsional motion) and the coupled cavities are favorable for strong optomechanical interactions in the torsional direction. PMID:25361336

Tian, Feng; Zhou, Guangya; Chau, Fook Siong; Deng, Jie

2014-11-01

197

Torsion of the testicular appendages: sonographic appearance.  

PubMed

Torsion of the testis and torsion of the testicular appendages have similar presenting features, namely, acute testicular pain and swelling. The former condition requires urgent surgical intervention to save the testis; the latter condition can be treated conservatively. Despite the frequency of torsion of the appendix testis, which is the most common cause of acute hemiscrotum in the child, only occasional references to this entity are found in the radiological literature. We describe five cases in which an enlarged, homogeneously echogenic appendix testis was seen medial or posterior to the head of the epididymis. All cases were accompanied by hydrocele and thickening of the scrotal wall. Among the five cases, enlargement of the head of the epididymis was seen in four and increased testicular blood flow in two. Scanning in the coronal and transverse planes above the testis was useful in locating the enlarged, twisted appendix. PMID:9166815

Strauss, S; Faingold, R; Manor, H

1997-03-01

198

Torsion of an encysted fluid collection.  

PubMed

Torsion of a cyst within the tunica vaginalis is a rare entity and clinical course can easily be confused with other diseases that cause acute scrotum. We report a 6-year-old child with 3 days of acute scrotum findings. Patient had surgery with the suspicion of testis torsion. Torsion of a cyst within the tunica vaginalis was found intraoperatively. In pathologic evaluation, a necrotic funicular cyst was diagnosed. Two different mechanisms were reported for the reason of this disease: hernia sac protrusion in the hydrocele sac and bell-clapper deformity. Our observations were on the side of bell-clapper deformity. We aimed to share our findings with this report. PMID:17619766

Senayli, Atilla; Senayli, Yesim; Sezer, Engin; Sezer, Taner

2007-01-01

199

Evidence for the distribution of angular velocity inside the sun and stars  

NASA Technical Reports Server (NTRS)

A round table discussion of problems of solar and stellar spindown and theory is presented. Observational evidence of the angular momentum of the solar wind is included, emphasizing the distribution of angular velocity inside the sun and stars.

1972-01-01

200

The Angular Momentum Dichotomy  

NASA Astrophysics Data System (ADS)

In the context of the formation of spiral galaxies the evolution and distribution of the angular momentum of dark matter halos have been discussed for more than 20 years, especially the idea that the specific angular momentum of the halo can be estimated from the specific angular momentum of its disk (e.g. Fall & Efstathiou (1980), Fall (1983) and Mo et al. (1998)). We use a new set of hydrodynamic cosmological simulations called Magneticum Pathfinder which allow us to split the galaxies into spheroidal and disk galaxies via the circularity parameter ?, as commonly used (e.g. Scannapieco et al. (2008)). Here, we focus on the dimensionless spin parameter ? = J |E|1/2 / (G M5/2) (Peebles 1969, 1971), which is a measure of the rotation of the total halo and can be fitted by a lognormal distribution, e.g. Mo et al. (1998). The spin parameter allows one to compare the relative angular momentum of halos across different masses and different times. Fig. 1 reveals a dichotomy in the distribution of ? at all redshifts when the galaxies are split into spheroids (dashed) and disk galaxies (dash-dotted). The disk galaxies preferentially live in halos with slightly larger spin parameter compared to spheroidal galaxies. Thus, we see that the ? of the whole halo reflects the morphology of its central galaxy. For more details and a larger study of the angular momentum properties of disk and spheroidal galaxies, see Teklu et al. (in prep.).

Teklu, Adelheid; Remus, Rhea-Silvia; Dolag, Klaus; Burkert, Andreas

2015-02-01

201

Angular momentum radio  

NASA Astrophysics Data System (ADS)

Wireless communication amounts to encoding information onto physical observables carried by electromagnetic (EM) fields, radiating them into surrounding space, and detecting them remotely by an appropriate sensor connected to an informationdecoding receiver. Each observable is second order in the fields and fulfills a conservation law. In present-day radio only the EM linear momentum observable is fully exploited. A fundamental physical limitation of this observable, which represents the translational degrees of freedom of the charges (typically an oscillating current along a linear antenna) and the fields, is that it is single-mode. This means that a linear-momentum radio communication link comprising one transmitting and one receiving antenna, known as a single-input-single-output (SISO) link, can provide only one transmission channel per frequency (and polarization). In contrast, angular momentum, which represents the rotational degrees of freedom, is multi-mode, allowing an angular-momentum SISO link to accommodate an arbitrary number of independent transmission channels on one and the same frequency (and polarization). We describe the physical properties of EM angular momentum and how they can be exploited, discuss real-world experiments, and outline how the capacity of angular momentum links may be further enhanced by employing multi-port techniques, i.e., the angular momentum counterpart of linear-momentum multiple-input-multiple-output (MIMO).

Thidé, B.; Tamburini, F.; Then, H.; Someda, C. G.; Mari, Elletra; Parisi, G.; Spinello, F.; Romanato, Fra

2014-02-01

202

Massive torsion modes, chiral gravity, and the Adler-Bell-Jackiw anomaly  

E-print Network

Regularization of quantum field theories introduces a mass scale which breaks axial rotational and scaling invariances. We demonstrate from first principles that axial torsion and torsion trace modes have non-transverse vacuum polarization tensors, and become massive as a result. The underlying reasons are similar to those responsible for the Adler-Bell-Jackiw (ABJ) and scaling anomalies. Since these are the only torsion components that can couple minimally to spin 1/2 particles, the anomalous generation of masses for these modes, naturally of the order of the regulator scale, may help to explain why torsion and its associated effects, including CPT violation in chiral gravity, have so far escaped detection. As a simpler manifestation of the reasons underpinning the ABJ anomaly than triangle diagrams, the vacuum polarization demonstration is also pedagogically useful. In addition it is shown that the teleparallel limit of a Weyl fermion theory coupled only to the left-handed spin connection leads to a counter term which is the Samuel-Jacobson-Smolin action of chiral gravity in four dimensions.

Lay Nam Chang; Chopin Soo

2003-03-17

203

Using ultrasounds for the estimation of the misalignment in plate-plate torsional rheometry  

NASA Astrophysics Data System (ADS)

A new method to accurately quantify the gap error arising from non-parallelism in plate-plate and cone-plate torsional rheometry is proposed. This method consists in monitoring the ultrasonic pulses sent by a transducer adapted to the rheometer bottom plate. The time of flight (TOF) of the echoes reflected by the rheometer upper plate, while it rotates at small angular velocity having a sample placed between the plates, is measured. As the sample acoustic velocity is constant and known, any variation in the TOF is correlated with changes in the distance between plates and thus, the misalignment is automatically determined.

Rodríguez-López, J.; Elvira, L.; Montero de Espinosa Freijo, F.; de Vicente, J.

2013-05-01

204

Primary omental torsion: A case report  

PubMed Central

A patient presented with an acute abdomen at the Emergency Department. The patient, a 69-year-old man, was admitted and underwent surgery with a provisional diagnosis of acute appendicitis. During surgery, omental torsion was diagnosed and the involved omentum was removed. The patient had no previous surgical history. Omental torsion is a rare cause of acute abdomen in children and adults who may present with various signs and symptoms; a preoperative diagnosis may therefore be difficult and can usually only be established during surgery. PMID:22110847

Scabini, Stefano; Rimini, Edoardo; Massobrio, Andrea; Romairone, Emanuele; Linari, Chiara; Scordamaglia, Renato; Marini, Luisito De; Ferrando, Valter

2011-01-01

205

Omental Torsion After Repeated Abdominal Blunt Trauma  

PubMed Central

Omental torsion is caused by the rotation of the greater omentum on its axis which may lead to tissue infarction and necrosis. It is a rare cause of acute abdomen. Signs, symptoms and paraclinical data are not specific. The patients usually undergo laparotomy for acute abdomen of poorly defined origin. High index of suspicious is required for the diagnosis of this entity. The diagnosis is usually confirmed after an explorative laparotomy. We present clinical characteristics and imaging findings of omental torsion in a young man following repeated blunt abdominal trauma. PMID:24396748

Hosseinpour, Mehrdad; Abdollahi, Azadeh; Jazayeri, Hoda; Talari, Hamid Reza; Sadeghpour, Ahmad

2012-01-01

206

Thermal Hall effect and geometry with torsion.  

PubMed

We formulate a geometric framework that allows us to study momentum and energy transport in nonrelativistic systems. It amounts to a coupling of the nonrelativistic system to the Newton-Cartan (NC) geometry with torsion. The approach generalizes the classic Luttinger's formulation of thermal transport. In particular, we clarify the geometric meaning of the fields conjugated to energy and energy current. These fields describe the geometric background with nonvanishing temporal torsion. We use the developed formalism to construct the equilibrium partition function of a nonrelativistic system coupled to the NC geometry in 2+1 dimensions and to derive various thermodynamic relations. PMID:25615492

Gromov, Andrey; Abanov, Alexander G

2015-01-01

207

Mag Lab U: Interactive Tutorials - Torsion Balance  

NSDL National Science Digital Library

This interactive Java tutorial allows users to play with a replica of the historic torsion balance used by Coulomb in his 18th-century experiments to measure the electrostatic force between charges. By carefully recording the measurements he obtained with his torsion balance, Coulomb was able to establish the law that bears his name. Coloumb's law states that the attraction or repulsion force between two electrical charges is proportional to their product and inversely proportional to the square of their distance apart. Mag Lab U is part of a large collection of web-based educational materials for K-20, developed by the National High Magnetic Field Laboratory at Florida State University.

2010-05-25

208

Thermal Hall Effect and Geometry with Torsion  

NASA Astrophysics Data System (ADS)

We formulate a geometric framework that allows us to study momentum and energy transport in nonrelativistic systems. It amounts to a coupling of the nonrelativistic system to the Newton-Cartan (NC) geometry with torsion. The approach generalizes the classic Luttinger's formulation of thermal transport. In particular, we clarify the geometric meaning of the fields conjugated to energy and energy current. These fields describe the geometric background with nonvanishing temporal torsion. We use the developed formalism to construct the equilibrium partition function of a nonrelativistic system coupled to the NC geometry in 2 +1 dimensions and to derive various thermodynamic relations.

Gromov, Andrey; Abanov, Alexander G.

2015-01-01

209

Primary omental torsion: A case report.  

PubMed

A patient presented with an acute abdomen at the Emergency Department. The patient, a 69-year-old man, was admitted and underwent surgery with a provisional diagnosis of acute appendicitis. During surgery, omental torsion was diagnosed and the involved omentum was removed. The patient had no previous surgical history. Omental torsion is a rare cause of acute abdomen in children and adults who may present with various signs and symptoms; a preoperative diagnosis may therefore be difficult and can usually only be established during surgery. PMID:22110847

Scabini, Stefano; Rimini, Edoardo; Massobrio, Andrea; Romairone, Emanuele; Linari, Chiara; Scordamaglia, Renato; Marini, Luisito De; Ferrando, Valter

2011-10-27

210

Ultrasonic rock drilling devices using longitudinal-torsional compound vibration  

Microsoft Academic Search

Nasa funded studies have proven that ultrasonics is a viable technology for extraterrestrial drilling. Previous research by the authors has indicated that ultrasonic longitudinal-torsional coupled vibrations may improve rock excavation. In this study, two approaches to the development of torsional output from a Langevin transducer are pursued: coupling the longitudinal mode with a torsional mode and degenerating the longitudinal mode

Patrick Harkness; Andrea Cardoni; Margaret Lucas

2009-01-01

211

Metamaterial broadband angular selectivity  

NASA Astrophysics Data System (ADS)

We demonstrate how broadband angular selectivity can be achieved with stacks of one-dimensionally periodic photonic crystals, each consisting of alternating isotropic layers and effective anisotropic layers, where each effective anisotropic layer is constructed from a multilayered metamaterial. We show that by simply changing the structure of the metamaterials, the selective angle can be tuned to a broad range of angles; and, by increasing the number of stacks, the angular transmission window can be made as narrow as desired. As a proof of principle, we realize the idea experimentally in the microwave regime. The angular selectivity and tunability we report here can have various applications such as in directional control of electromagnetic emitters and detectors.

Shen, Yichen; Ye, Dexin; Wang, Li; Celanovic, Ivan; Ran, Lixin; Joannopoulos, John D.; Solja?i?, Marin

2014-09-01

212

An advanced theory of thin-walled girders with application to ship vibrations  

Microsoft Academic Search

The paper presents an outline of the advanced theory of thin-walled girders. The improvement includes shear influence on torsion as an extension of shear influence on bending. The analogy between bending and torsion is recognized and pointed out throughout the paper. Complete differential equations of coupled flexural and torsional vibrations for a prismatic girder are derived. In addition, the 8

I. Senjanovi?; S. Tomaševi?; N. Vladimir

2009-01-01

213

Angular shear plate  

SciTech Connect

One or more disc-shaped angular shear plates each include a region thereon having a thickness that varies with a nonlinear function. For the case of two such shear plates, they are positioned in a facing relationship and rotated relative to each other. Light passing through the variable thickness regions in the angular plates is refracted. By properly timing the relative rotation of the plates and by the use of an appropriate polynomial function for the thickness of the shear plate, light passing therethrough can be focused at variable positions.

Ruda, Mitchell C. (Tucson, AZ); Greynolds, Alan W. (Tucson, AZ); Stuhlinger, Tilman W. (Tucson, AZ)

2009-07-14

214

Torsional ultrasound mode versus combined torsional and conventional ultrasound mode phacoemulsification for eyes with hard cataract  

PubMed Central

Purpose To compare torsional versus combined torsional and conventional ultrasound modes in hard cataract surgery regarding ultrasound energy and time and effect on corneal endothelium. Settings Kasr El Aini hospital, Cairo University, and International Eye Hospital, Cairo, Egypt. Methodology Ninety-eight eyes of 63 patients were enrolled in this prospective comparative randomized masked clinical study. All eyes had nuclear cataracts of grades III and IV using the Lens Opacities Classification System III (LOCS III). Two groups were included, each having an equal number of eyes (49). The treatment for group A was combined torsional and conventional US mode phacoemulsification, and for group B torsional US mode phacoemulsification only. Pre- and post-operative assessments included best corrected visual acuity (BCVA), intraocular pressure (IOP), slit-lamp evaluation, and fundoscopic evaluation. Endothelial cell density (ECD) and central corneal thickness (CCT) were measured preoperatively, 1 day, 7 days, and 1 month postoperatively. All eyes were operated on using the Alcon Infiniti System (Alcon, Fort Worth, TX) with the quick chop technique. All eyes were implanted with AcrySof SA60AT (Alcon) intraocular lens (IOL). The main phaco outcome parameters included the mean ultrasound time (UST), the mean cumulative dissipated energy (CDE), and the percent of average torsional amplitude in position 3 (%TUSiP3). Results Improvement in BCVA was statistically significant in both groups (P < 0.001). Comparing UST and CDE for both groups revealed results favoring the pure torsional group (P = 0.002 and P < 0.001 for UST; P = 0.058 and P = 0.009 for CDE). As for %TUSiP3, readings were higher for the pure torsional group (P = 0.03 and P = 0.01). All changes of CCT, and ECD over time were found statistically significant using one-way ANOVA testing (P < 0.001). Conclusion Both modes are safe in hard cataract surgery, however the pure torsional mode showed less US energy used. PMID:21792288

Fakhry, Mohamed A; Shazly, Malak I El

2011-01-01

215

Textile composite rods operating in torsion  

Microsoft Academic Search

The load-carrying capacity of thick-walled composite rods loaded in torsion may be effectively controlled through variation of the winding scheme and structural and technological parameters of winding within the framework of the textile technology. Increase of the monolayer shear strength is attained by means of proper selection of the optimum reinforcement angle and degree of fibre weave during winding. This

Yu. M. Tarnopol'skii; V. L. Kulakov; A. M. Zakrzhevskii; D. D. Mungalov

1996-01-01

216

Gravitational dispersion in a torsional wave machine  

E-print Network

We demonstrate that mechanical waves traveling in a torsional, mechanical wave machine exhibit dispersion due to gravity and the discreteness of the medium. We also show that although the dispersion due to discreteness is negligible, the dispersion due to gravity can be easily measured, and can be shown to disappear in a zero-gravity environment.

Rafael de la Madrid; Alejandro Gonzalez; George Irwin

2014-09-01

217

Torsion of the testis: techniques of assessment.  

PubMed

Results of treatment of torsion of the testicle can be measured only by determining the rate of testicular salvage, which has been low but has improved in recent years. The Doppler instruments and the technique of scrotal imaging with the gamma camera provide noninvasive and rapid diagnostic aids with a high degree of accuracy. There is evidence that these techniques will aid in the differential diagnosis of equivocal cases, and thus lower the incidence of delay in the diagnosis of torsion, a cause of lower than optimal salvage rates in the past. Fluorescein staining can also be used in the operating room if there is a question of testicular viability. The availability of these new modalities, however, is no substitute for early evaluation. Quick referral from primary physicians and a high awareness of torsion as a cause of acute scrotal pain and swelling are extremely important. Reviews clearly indicate that improved salvage rates are achieved with early evaluation and treatment. Therefore the urologist has a continuing responsibility to educate pediatricians, family practitioners, and emergency room physicians in the urgency of diagnosis and treatment in cases of testicular torsion. Although new diagnostic aids are useful, only early surgical exploration can save a torsive testis. PMID:462683

Smith, S P; King, L R

1979-06-01

218

Torsional vibration reduction using passive nonlinear absorbers  

Microsoft Academic Search

This paper considers the dynamic performance of systems of centrifugal pendulum vibration absorbers that are used to attenuate torsional vibrations in rotating systems. These absorbers, which can be found in certain IC engines and helicopter rotors, consist of movable masses whose centers of mass are kinematically restricted to move along prescribed paths relative to the rotor of interest. The most

Steven W. Shaw; Abdallah Alsuwaiyan

2000-01-01

219

Gravitational dispersion in a torsional wave machine  

NASA Astrophysics Data System (ADS)

We demonstrate that mechanical waves traveling in a torsional, mechanical wave machine exhibit dispersion due to gravity and the discreteness of the medium. We also show that although the dispersion due to discreteness is negligible, the dispersion due to gravity can be easily measured and can be shown to disappear in a zero-gravity environment.

de la Madrid, Rafael; Gonzalez, Alejandro; Irwin, George M.

2014-12-01

220

Asymptomatic uterine torsion in a pregnant woman.  

PubMed

Some degree rotation of the gravid uterus in the third trimester of pregnancy is not an abnormal finding. However, extreme uterine torsion of 180° around its cervical junction is a relatively rare event in obstetrical practice. We report here such a case that detected at laparotomy for an emergency cesarean section due to rapture of amniotic membrane. PMID:25278659

Farhadifar, Fariba; Nikkhoo, Bahram; Shahgheibi, Sholeh; Soofizadeh, Nasrin; Rezaie, Masomeh

2014-08-01

221

Test particle acceleration in torsional fan reconnection  

NASA Astrophysics Data System (ADS)

Magnetic reconnection is understood to be a potential mechanism for particle acceleration in astrophysical and space plasmas, especially in solar flares. Torsional fan reconnection is one of the proposed mechanisms for steady-state three-dimensional (3D) magnetic reconnection. By using the magnetic and electric fields for `torsional fan reconnection', the features of test particle acceleration with input parameters for the solar corona are investigated numerically. We show that torsional fan reconnection is potentially an efficient particle accelerator and a proton can gain up to tens of MeV of kinetic energy within only a few milliseconds. Although the final kinetic energy of the accelerated particle depends on the injection position but there exists only one scenario for the particle's trajectory with different initial positions in which the particle is accelerated on the fan plane. Moreover, adopting either spatially uniform or non-uniform localized plasma resistivity does not much influence the features of trajectory. These results are compared with those of torsional spine reconnection.

Hosseinpour, M.

2014-12-01

222

Axioms for higher torsion invariants of smooth bundles.  

E-print Network

We explain the relationship between various characteristic classes for smooth manifold bundles known as ``higher torsion'' classes. We isolate two fundamental properties that these cohomology classes may or may not have: additivity and transfer. We show that higher Franz-Reidemeister torsion and higher Miller-Morita-Mumford classes satisfy these axioms. Conversely, any characteristic class of smooth bundles satisfying the two axioms must be a linear combination of these two examples. We also show how higher torsion invariants can be computed using only the axioms. Finally, we explain the conjectured formula of S. Goette relating higher analytic torsion classes and higher Franz-Reidemeister torsion.

Kiyoshi Igusa

223

Gears: Determining Angular Velocity  

NSDL National Science Digital Library

Students work as engineers and learn to conduct controlled experiments by changing one experimental variable at a time to study its effect on the experiment outcome. Specifically, they conduct experiments to determine the angular velocity for a gear train with varying gear ratios and lengths. Student groups assemble LEGO® MINDSTORMS® NXT robots with variously sized gears in a gear train and then design programs using the NXT software to cause the motor to rotate all the gears in the gear train. They use the LEGO data logging program and light sensors to set up experiments. They run the program with the motor and the light sensor at the same time and analyze the resulting plot in order to determine the angular velocity using the provided physics-based equations. Finally, students manipulate the gear train with different gears and different lengths in order to analyze all these factors and figure out which manipulation has a higher angular velocity. They use the equations for circumference of a circle and angular velocity; and convert units between radians and degrees.

AMPS GK-12 Program,

224

Angular momentum conservation demonstration  

NSDL National Science Digital Library

A short article describing the fabrication and operation of a simple angular momentum conservation demonstration. The demonstration is based on a Lazy Susan, and cylindrical brass weights tied with a nylon string. The string can be pulled or released changing the radius or rotation of the weights.

Berg, Richard E.; Anders, Robert E.

2010-12-23

225

a Rotatable Torsion Balance for a New Test of the Equivalence Principle.  

NASA Astrophysics Data System (ADS)

An improved rotatable torsion balance has been built at UC Irvine to be used for a new test of the equivalence of inertial and gravitational mass, with the ability to use both the earth and the sun as acceleration sources. The suspended torsion balance body contains four cylindrical test masses of copper and four of lead press-fit into a cylindrical aluminum body in a highly stable configuration designed to minimize its mass multipole moments. The balance body is trimmed to reduce measured undesired mass moments due to inhomogeneities in the materials and to manufacturing imperfections. To reduce thermal noise, the balance body is suspended by an 80 cm long quartz fiber, which has a high Q. A Q of about 300,000 for a 20 micron diameter bare quartz fiber at 3.6 mHz has been achieved, corresponding to an amplitude damping time of about one year. The instrument is operated in a turn/stop mode in which it is rotated to a new position, then stopped for data taking. To prevent inelastic strain of the torsion fiber when the instrument is rotated, the balance body is gently forced to co-rotate with its housing by a small spinning horizontal magnetic field servoed to the angular readout. This balance was used to measure the fractional difference in acceleration between lead and copper towards the sun to a part in 10 ^{11}, with the resulting data consistent with Newtonian gravitation.

Beilby, Mark Alfred

1995-01-01

226

Design and analysis of a torsion braid pendulum displacement transducer  

NASA Technical Reports Server (NTRS)

The dynamic properties at various temperatures of braids impregnated with polymer can be measured by using the braid as the suspension of a torsion pendulum. This report describes the electronic and mechanical design of a torsional braid pendulum displacement transducer which is an advance in the state of the art. The transducer uses a unique optical design consisting of refracting quartz windows used in conjunction with a differential photocell to produce a null signal. The release mechanism for initiating free torsional oscillation of the pendulum has also been improved. Analysis of the precision and accuracy of the transducer indicated that the maximum relative error in measuring torsional amplitude was approximately 0. A serious problem inherent in all instruments which use a torsional suspension was analyzed: misalignment of the physical and torsional axes of the torsional member which results in modulation of the amplitude of the free oscillation.

Rind, E.; Bryant, E. L.

1981-01-01

227

N= 4 mechanics with diverse (4, 4, 0) multiplets: Explicit examples of hyper-Kähler with torsion, Clifford Kähler with torsion, and octonionic Kähler with torsion geometries  

SciTech Connect

We present simple models of N= 4 supersymmetric mechanics with ordinary and mirror linear (4, 4, 0) multiplets that give a transparent description of Hyper-Kähler with Torsion (HKT), Clifford Kähler with Torsion (CKT), and Octonionic Kähler with Torsion (OKT) geometries. These models are treated in the N= 4 and N=2 superfield approaches, as well as in the component approach. Our study makes manifest that the CKT and OKT supersymmetric sigma models are distinguished from the more simple HKT models by the presence of extra holomorphic torsion terms in the supercharges.

Fedoruk, Sergey, E-mail: fedoruk@theor.jinr.ru; Ivanov, Evgeny, E-mail: eivanov@theor.jinr.ru [Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna, Moscow Region (Russian Federation)] [Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna, Moscow Region (Russian Federation); Smilga, Andrei, E-mail: smilga@subatech.in2p3.fr [SUBATECH, Université de Nantes, 4 rue Alfred Kastler, BP 20722, Nantes 44307 (France)] [SUBATECH, Université de Nantes, 4 rue Alfred Kastler, BP 20722, Nantes 44307 (France)

2014-05-15

228

Quasi-steady prediction of coupled bending-torsion flutter under rotating stall  

NASA Astrophysics Data System (ADS)

A method is presented in this paper to predict cascade flutter under subsonic stalled flow condition in a quasi-steady manner. The ability to predict the occurrence of aeroelastic flutter is highly important from the compressor design point of view. In the present work, the well known Moore-Greitzer compression system model is used to evaluate the flow under rotating stall and the linearized aerodynamic theory of Whitehead is used to estimate the blade loading. The cascade stability is then predicted by solving the structural model, which is posed as a complex eigenvalue problem. The possibility of occurrence of flutter in both bending and torsional modes is considered and the latter is found to be the dominant one, under subsonic stalled flow, for a large range of frequency ratios examined. It is also shown that the design of compressor blades at frequency ratios close to unity may result in rapid initiation of torsional flutter in the presence of stalled flow. A frequency ratio of 0.9 is primarily emphasized for most part of the study as many interesting features are revealed and the results are physically interpreted. Roughly a pitchfork pattern of energy distribution appears to occur between bending mode and torsional mode which ensures that only one flutter mode is possible at any instant in time. A bifurcation from bending flutter to torsional flutter is shown to occur during which the frequency of the two vibrating modes appear to coalesce for a very short period of time.

Ananth, S. M.; Kushari, A.; Venkatesan, C.

2013-11-01

229

Dynamics of a 3dof torsional system with a dry friction controlled path  

Microsoft Academic Search

A three-degrees of freedom semi-definite torsional system representing an automotive driveline is studied in presence of a torque converter clutch that manifests itself as a dry friction path. An analytical procedure based on the linear system theory is proposed first to establish the stick-to-slip boundaries. Smoothened and discontinuous Coulomb friction formulations are then applied to the nonlinear system, and the

Chengwu Duan; Rajendra Singh

2006-01-01

230

Investigations of magnetic hysteresis of barium ferrite using the torsion pendulum method  

SciTech Connect

The magnetic stiffness is measured by the torsion pendulum method as a function of the applied field. Measurements are performed on random assemblies of chemically coprecipitated barium ferrite powders. The magnetic stiffness for both minor and major loops of the hysteresis cycle is measured and compared with calculated curves based on the model of coherent rotation. The discrepancies between theory and experiment are partly due to the effect of magnetic interaction.

Richter, H.J.; Hempel, K.A.

1988-11-15

231

On the torsion effects of a relativistic spin fluid in early cosmology  

E-print Network

In this work we investigate the effects of torsion in the framework of Einstein-Cartan theory in early cosmology. We study solutions for a homogeneous and isotropic relativistic Weyssenhoff spin fluid with dynamical timelike axial current, also homogeneous and isotropic. The general solutions can mostly be described by means of three particular solutions. The properties of these solutions (such as singularity avoidance and primordial or late accelerated expansion) are analysed and depend on the relations between the source parameters.

G. de Berredo-Peixoto; E. A. de Freitas

2009-10-01

232

Metric-scalar gravity with torsion and the measurability of the non-minimal coupling  

E-print Network

The "measurability" of the non-minimal coupling is discussed by considering the correction to the Newtonian static potential in the semi-classical approach. The coefficient of the "gravitational Darwin term" (GDT) gets redefined by the non-minimal torsion-scalar couplings. Based on a similar analysis of the GDT in the effective field theory approach to non-minimal scalar we conclude that for reasonable values of the couplings the correction is very small.

A. Accioly; H. Blas

2005-03-19

233

A Novel Angular Acceleration Sensor Based on the Electromagnetic Induction Principle and Investigation of Its Calibration Tests  

PubMed Central

An angular acceleration sensor can be used for the dynamic analysis of human and joint motions. In this paper, an angular acceleration sensor with novel structure based on the principle of electromagnetic induction is designed. The method involves the construction of a constant magnetic field by the excitation windings of sensor, and the cup-shaped rotor that cut the magnetic field. The output windings of the sensor generate an electromotive force, which is directly proportional to the angular acceleration through the electromagnetic coupling when the rotor has rotational angular acceleration. The mechanical structure and the magnetic working circuit of the sensor are described. The output properties and the mathematical model including the transfer function and state-space model of the sensor are established. The asymptotical stability of the sensor when it is working is verified by the Lyapunov Theorem. An angular acceleration calibration device based on the torsional pendulum principle is designed. The method involves the coaxial connection of the angular acceleration sensor, torsion pendulum and a high-precision angle sensor, and then an initial external force is applied to the torsion pendulum to produce a periodic damping angle oscillation. The angular acceleration sensor and the angle sensor will generate two corresponding electrical signals. The sensitivity coefficient of the angular acceleration sensor can be obtained after processing these two-channel signals. The experiment results show that the sensitivity coefficient of the sensor is about 17.29 mv/Krad·s2. Finally, the errors existing in the practical applications of the sensor are discussed and the corresponding improvement measures are proposed to provide effective technical support for the practical promotion of the novel sensor. PMID:23941911

Zhao, Hao; Feng, Hao

2013-01-01

234

A novel angular acceleration sensor based on the electromagnetic induction principle and investigation of its calibration tests.  

PubMed

An angular acceleration sensor can be used for the dynamic analysis of human and joint motions. In this paper, an angular acceleration sensor with novel structure based on the principle of electromagnetic induction is designed. The method involves the construction of a constant magnetic field by the excitation windings of sensor, and the cup-shaped rotor that cut the magnetic field. The output windings of the sensor generate an electromotive force, which is directly proportional to the angular acceleration through the electromagnetic coupling when the rotor has rotational angular acceleration. The mechanical structure and the magnetic working circuit of the sensor are described. The output properties and the mathematical model including the transfer function and state-space model of the sensor are established. The asymptotical stability of the sensor when it is working is verified by the Lyapunov Theorem. An angular acceleration calibration device based on the torsional pendulum principle is designed. The method involves the coaxial connection of the angular acceleration sensor, torsion pendulum and a high-precision angle sensor, and then an initial external force is applied to the torsion pendulum to produce a periodic damping angle oscillation. The angular acceleration sensor and the angle sensor will generate two corresponding electrical signals. The sensitivity coefficient of the angular acceleration sensor can be obtained after processing these two-channel signals. The experiment results show that the sensitivity coefficient of the sensor is about 17.29 mv/Krad·s2. Finally, the errors existing in the practical applications of the sensor are discussed and the corresponding improvement measures are proposed to provide effective technical support for the practical promotion of the novel sensor. PMID:23941911

Zhao, Hao; Feng, Hao

2013-01-01

235

Interfacing a torsion pendulum with a microcomputer  

SciTech Connect

Shear modulus testing is performed on the torsion pendulum at the General Electric Neutron Devices Department (GEND) as a means of gauging the state of cure for a polymer system. However, collection and reduction of the data to obtain the elastic modulus necessitated extensive operator involved measurements and calculations, which were subject to errors. To improve the reliability of the test, an analog-to-digital interface was designed and built to connect the torsion pendulum with a minicomputer. After the necessary programming was prepared, the system was tested and found to be an improvement over the old procedure in both quality and time of operation. An analysis of the data indicated that the computer generated modulus data were equivalent to the hand method data, but potential operator errors in frequency measurements and calculations were eliminated. The interfacing of the pendulum with the computer resulted in an overall time savings of 52 percent.

Bush, J.A.; Newby, J.W.

1983-02-24

236

Axial and torsional fatigue behavior of Waspaloy  

NASA Technical Reports Server (NTRS)

The cyclic flow response and crack growth behavior of Waspaloy at room temperature and 650 C under tensile loading and torsional loading was studied, for two conditions of Waspaloy: fine grain, large gamma prime size; coarse grain, small gamma prime size. The fine grain material showed 5 to 10 percent hardening after about 10 percent of life, with sequent softening to failure at both themperature levels. The coarse grain material showed either stable response or monotonic softening to failure. Early crack initiation was observed on planes of maximum shear, with eventual branching to principle planes under torsional loading; cracks were always normal to load axis under tensile loading. Also, crack paths were intergranular at 650 C, mostly transgranular at room temperature.

Zamrik, S.; Mirdamadi, M.; Zahiri, F.

1986-01-01

237

Intratesticular Epidermoid Cyst Masquerading as Testicular Torsion  

PubMed Central

Epidermoid cysts are benign tumors that comprise approximately 1% of all testicular masses. They usually present as painless masses that can be identified on scrotal ultrasound as well-demarcated intratesticular lesions with mixed echogenicity. This case report describes a rare presentation of an extremely large intratesticular epidermoid cyst with clinical and radiologic findings more consistent with testicular torsion. The sizeable cyst obliterated the surrounding testicular parenchyma, causing it to appear on scrotal Doppler ultrasound as a testicle devoid of blood flow. This obliteration also resulted in failure to identify a testicular mass on physical examination or imaging. The current literature contains previous reports of extratesticular epidermoid cysts presenting as torsion; however, this is the first report of an intratesticular epidermoid cyst presenting in this manner. Though smaller cysts may be managed effectively with testicular-sparing surgery, optimal management of a cyst this size requires orchiectomy.

Slawin, Jeremy; Slawin, Kevin

2014-01-01

238

Coherent Control of Angular Momentum Transfer in Resonant Two-Photon Light-Matter Interaction  

SciTech Connect

We show experimentally and theoretically that a polarization-shaped femtosecond laser pulse with a zero net angular momentum creates a net angular momentum in atomic rubidium during resonant two-photon excitation. The necessary conditions for the creation of a nonzero angular momentum as well as the excitation efficiencies are analyzed in the framework of second-order time-dependent perturbation theory.

Malik, D. A.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Zande, W. J. van der [Radboud University Nijmegen, Institute for Molecules and Materials, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands)

2010-04-02

239

Surgical correction of idiopathic medial femoral torsion  

Microsoft Academic Search

Summary  We reviewed 28 hips in 14 patients with severe bilateral idiopathic medial femoral torsion which had been corrected by intertrochanteric\\u000a rotation osteotomy using crossed pins for fixation and a hip spica. There were 10 girls and 4 boys with a mean age of 7 years\\u000a and 9 months. All had functional and cosmetic disability before operation. The average follow up

J. S. Shiml; L. T. Staheli; B. N. Holm

1995-01-01

240

ELKO and Dirac Spinors seen from Torsion  

E-print Network

In this paper, the recently-introduced ELKO and the well-known Dirac spinor fields will be compared; however, instead of comparing them under the point of view of their algebraic properties or their dynamical features, we will proceed by investigating the analogies and similarities in terms of their geometrical character viewed from the perspective of torsion. The paper will be concluded by sketching some consequences for the application to cosmology and particle physics.

Luca Fabbri; Stefano Vignolo

2014-07-30

241

Electronic properties of carbon nanotubes under torsion  

NASA Astrophysics Data System (ADS)

A computationally-effective approach for calculating the electromechanical behavior of SWNTs and MWNTs of the dimensions used in nano-electronic devices has been developed. It is a mixed finite element-tight-binding code carefully designed to realize significant time saving in calculating deformation-induced changes in electrical transport properties of the nanotubes. The effect of the MWNT diameter and chirality on the conductance after mechanical deformation was investigated. In case of torsional deformation, results revealed the conductance of MWNTs to depend strongly on the diameter, since bigger MWNTs reach the buckling load under torsion much earlier, their electrical conductivity changes more easily than in small diameter ones. For the same outer diameter, zigzag MWNTs are more sensitive to twisting than armchair MWNTs since the hexagonal cells are oriented in such a way that they oppose less resistance to the buckling deformations due to torsion. Thus small diameter armchair MWNTs should work better if used as conductors, while big diameter zigzag MWNTs are more suitable for building sensors.

Pantano, Antonio; Campanella, Dario; Montinaro, Nicola; Cerniglia, Donatella

2013-01-01

242

Polyorchidism with presumed contralateral intrauterine testicular torsion  

PubMed Central

INTRODUCTION Polyorchidism was first described by Blasius in 16701 during a routine autopsy. We report a child with unilateral polyorchidism and a contralateral absent testis, a combination not reported previously. PRESENTATION OF CASE A 2-year-old boy was referred to the outpatient clinic with an impalpable left testis. At laparoscopy, the left vas deferens and testicular vessels ended blindly proximal to a closed internal ring. No gonadal tissue was identified. On the right side, a single vas deferens and testicular vessels were seen entering the internal ring as normal. The right side of the scrotum was explored and two testes were identified within a single tunica vaginalis. DISCUSSION Polyorchidism is rare with a literature search identifying approximately 230 reported cases. Whilst prenatal testicular torsion is increasing being recognized and treated as a surgical emergency,9 prenatal testicular torsion in association with polyorchidism has not been previously reported. CONCLUSION We describe a unique case of a 2-year-old boy with right-sided polyorchidism and an absent left testis associated with a blind ending vas deferens and testicular vessels, presumed secondary to intrauterine testicular torsion. PMID:25462053

Leodoro, B.M.; Beasley, S.W.; Stringer, M.D.

2014-01-01

243

Medial femoral torsion: experience with operative treatment.  

PubMed

Seventy-eight patients who had undergone bilateral derotational osteotomy of the femur for medial femoral torsion were reviewed to evaluate the procedure and to determine the frequency of postoperative complications. Patients averaged 6 years of age at the time of the procedure; girls predominated. Before derotational osteotomy, the mean hip rotation measurements were 84 degrees medially and 16 degrees laterally; following the procedure, mean hip rotations were 41 degrees medially and 51 degrees laterally. Medial femoral torsion was reduced from 54 degrees mean to 14 degrees. Balancing these favorable results, however, was a 15% risk of complications; 12 of our patients had problems associated with loss of fixation, errors in amount of correction, fractures, heel ulcer, or infection. Derotational osteotomy is only justified for the child with a persistent severe disability from medial femoral torsion. The parents should be aware of the significant risks and the lack of evidence for any long-term adverse effects if moderate MFT is left uncorrected. PMID:7371256

Staheli, L T; Clawson, D K; Hubbard, D D

1980-01-01

244

An extension of the high-resolution millimeter- and submillimeter-wave spectrum of methanol to high angular momentum quantum numbers  

NASA Technical Reports Server (NTRS)

The high-resolution laboratory millimeter- and submillimeter-wave spectra of C-12H(3)OH and C-13H(3)OH have been extended to include transitions involving significantly higher angular momentum quantum numbers than studied previously. For C-12H(3)OH, the data set now includes 549 A torsional substate transitions and 524 E torsional substate transitions through J is not greater than 24, exclusive of blends. For C-13H(3)OH the data set now includes 453 A torsional substate transitions and 440 E torsional substate transitions through J is not greater than 24, exclusive of blends. The extended internal axis method Hamiltonian has been used to analyze the transitions to experimental accuracy. The molecular constants determined by this approach have been used to predict accurately the frequencies of many transitions through J = 25 not measured in the laboratory.

Anderson, Todd; Herbst, Eric; De Lucia, Frank C.

1992-01-01

245

Mechanisms of testicular torsion and potential protective agents.  

PubMed

Testicular torsion is a urological emergency most commonly seen in adolescence, involving a decrease in blood flow in the testis resulting from torsion of the spermatic cord that can result in gonad injury or even loss if not treated in time. Testicular ischaemia-reperfusion injury represents the principle pathophysiology of testicular torsion, with ischaemia caused by twisting of the spermatic cord, and reperfusion on its subsequent release. Many cellular and molecular mechanisms are involved in ischaemia-reperfusion injury following testicular torsion. Studies have investigated the use of pharmacological agents as supportive therapy to surgical repair in order to prevent the adverse effects of testicular torsion. Numerous substances have been proposed as important in the prevention of post-ischaemia-reperfusion testicular injury. A range of chemicals and drugs has been successfully tested in animal models for the purpose of mitigating the dangerous effects of ischaemia-reperfusion in testis torsion. PMID:24934447

Karaguzel, Ersagun; Kadihasanoglu, Mustafa; Kutlu, Omer

2014-07-01

246

Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error  

SciTech Connect

We investigate the torsion potentials in two prototypical ?-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains.

Sutton, Christopher; Gray, Matthew T.; Brunsfeld, Max; Parrish, Robert M.; Sherrill, C. David; Sears, John S.; Brédas, Jean-Luc, E-mail: jean-luc.bredas@chemistry.gatech.edu, E-mail: thomas.koerzdoerfer@uni-potsdam.de [School of Chemistry and Biochemistry and Center for Computational Molecular Science and Technology, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)] [School of Chemistry and Biochemistry and Center for Computational Molecular Science and Technology, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Körzdörfer, Thomas, E-mail: jean-luc.bredas@chemistry.gatech.edu, E-mail: thomas.koerzdoerfer@uni-potsdam.de [School of Chemistry and Biochemistry and Center for Computational Molecular Science and Technology, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States) [School of Chemistry and Biochemistry and Center for Computational Molecular Science and Technology, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Computational Chemistry, Institute of Chemistry, University of Potsdam, D-14476 Potsdam (Germany)

2014-02-07

247

Symmetries of the Dirac operator with skew-symmetric torsion  

E-print Network

In this paper, we consider the symmetries of the Dirac operator derived from a connection with skew-symmetric torsion. We find that the generalized conformal Killing-Yano tensors give rise to symmetry operators of the massless Dirac equation, provided an explicitly given anomaly vanishes. We show that this gives rise to symmetries of the Dirac operator in the case of strong Kahler with torsion (KT) and strong hyper-Kahler with torsion (HKT) manifolds.

Tsuyoshi Houri; David Kubiznak; Claude Warnick; Yukinori Yasui

2010-02-18

248

Pull-in study of an electrostatic torsion microactuator  

Microsoft Academic Search

Pull-in study of an electrostatic microactuator is essential for making the electrostatic actuation more effective. In this paper, pull-in analysis is presented for an electrostatic torsion microactuator. The torsion microactuator can be used as a microtorsion mirror. A polynomial algebraic equation for the pull-in voltage and pull-in angle of a torsion microactuator is derived. Two types of microactuators fabricated using

Ofir Degani; Eran Socher; Ariel Lipson; T. Lejtner; Dan J. Setter; Shmuel Kaldor; Yael Nemirovsky

1998-01-01

249

Torsion-Gravity for Dirac fields and their effective phenomenology  

E-print Network

We will consider the torsional completion of gravity for a background filled with Dirac matter fields, studying the weak-gravitational non-relativistic approximation, in view of an assessment about their effective phenomenology: we discuss how the torsionally-induced non-linear interactions among fermion fields in this limit are compatible with all experiments, and remarks on the role of torsion to suggest new physics are given.

Luca Fabbri

2014-01-14

250

Dynamic deformation and fracture behavior of ultrafine-grained aluminum alloy fabricates by equal-channel angular pressing  

NASA Astrophysics Data System (ADS)

In the present study, ultrafine-grained microstructures of a conventional 5083 aluminum alloy were fabricated by equal-channel angular pressing, and their dynamic deformation and fracture behavior were investigated. Dynamic torsional tests were conducted on four aluminum alloy specimens using a torsional Kolsky bar, and then the test data were analyzed in relation to microstructures, tensile properties, and adiabatic shear-banding behavior. The equal-channel angular-pressed (ECAP) specimens consisted of ultrafine grains and contained a considerable amount of second-phase particles, which were refined and distributed homogeneously in the matrix as the equal-channel angular pressing pass number increased. The dynamic torsional test results indicated that the maximum shear stress increased, while the fracture shear strain remained constant, with increasing equal-channel angular pressing pass number. Observation of the deformed area beneath the dynamically fractured surface showed that a number of voids initiated mainly at second-phase particle/matrix interfaces and that the number of voids increased with increasing pass number. Adiabatic shear bands of 200 to <300 µm in width were formed in the as-extruded and 1-pass ECAP specimens having coarser particles, whereas they were hardly formed in the four-pass and eight-pass ECAP specimens having finer particles. The possibility of adiabatic shear-band formation was explained by concepts of absorbed deformation energy and void initiation.

Kim, Yang Gon; Hwang, Byoungchul; Lee, Sunghak; Kim, Woo Gyeom; Shin, Dong Hyuk

2005-11-01

251

Axioms for Higher Twisted Torsion Invariants of Smooth Bundles.  

E-print Network

This paper attempts to investigate the space of various characteristic classes for smooth manifold bundles with local system on the total space inducing a ?finite holonomy covering. These classes are known as twisted higher torsion classes. We will give a system of axioms that we require these cohomology classes to satisfy. Higher Franz Reidemeister torsion and twisted versions of the higher Miller-Morita-Mumford classes will satisfy these axioms. We will show that the space oftwisted torsion invariants is two dimensional or one dimensional depending on the torsion degree and spanned by these two classes. The proof will greatly depend on results on the equivariant Hatcher constructions developed in a separate paper.

Christopher Ohrt

252

Determination of diesel engine cylinder gas torques from speed fluctuations with a high-fidelity crankshaft torsional model  

SciTech Connect

An experimental investigation was conducted to develop a method of predicting cylinder indicated torques in a reciprocating engine by measurement of crankshaft angular velocity fluctuations. Cylinder indicated pressures were measured for all three cylinders of a two-stroke Diesel engine with pressure transducers. Time-resolved angular position was measured at the crankshaft front and at the flywheel. A six degree-of-freedom torsional crankshaft model was developed. Two solution methods are described to solve the equations of motion: a time-marching ODE solver, and a Finite Element solution in the time domain. Using these methods with the measured cylinder torques, the angular positions are predicted and compared to measured angular positions for model calibration. An inverse solution method was developed to determine the cylinder indicated torques from the measured angular position at the crankshaft endpoints. The method is theoretically demonstrated to be useful for explicit solutions for two-stroke engines up to three cylinders, and four-stroke engines up to four cylinders. Experimental results show that the method is useful in predicting cylinder indicated torques from angular velocity measurements.

Swanson, W.J.

1998-12-01

253

Experimental method for determination of bending and torsional rigidities of advanced composite laminates  

SciTech Connect

This paper presents an experimental method for the determination of the bending and torsional rigidities of advanced fiber composite laminates with the aid of laser holographic interferometry. The proposed method consists of a four-point bending test and a resonance test. The bending rigidity ratio (D{sub 12}/D{sub 22}) can be determined from the fringe patterns of the four-point bending test. The bending rigidities (D{sub 11} and D{sub 22}) and the torsional rigidity (D{sub 66}) are calculated from the natural frequencies of cantilever plates of the resonance test. The test specimens are carbon/epoxy cross-ply laminates. The adequacy of the experimental method is confirmed by comparing the measured rigidities with the theoretical values obtained from classical lamination theory (CLT) by using the measured tensile properties. The results show that the present method can be used to evaluate the rigidities of orthotropic laminates with reasonably good accuracy.

Maeda, Takenori [Univ. of Tsukuba, Ibaraki (Japan). Institute of Engineering Mechanics

1995-11-01

254

Torsion-rotation analysis of OH stretch overtone-torsion combination bands in methanol  

NASA Astrophysics Data System (ADS)

We report rotationally resolved spectra of jet-cooled methanol for the OH stretch overtones, 2v1 and 3v1, and for the torsional combinations, 2v1+v12, 2v1+2v12, 3v1+v12, and 3v1+2v12. The spectra are obtained by direct excitation from the vibrational ground state with an infrared laser pulse. Population in the resulting upper state levels is detected by infrared laser assisted photofragment spectroscopy (IRLAPS). Global fits of the spectra to the Herbst Hamiltonian yield the torsional and rotational parameters, including F, ?, V3, and V6, for each OH stretch excited state. For each quantum of OH stretch excitation, we find that the torsional barrier height V3 increases by 40.9±1.9 cm-1 and the torsional inertial F decreases by 0.89±0.02 cm-1. With reference to ab initio calculations, we explain the increase in V3 in terms of changes in the electronic structure of methanol as the OH bond is elongated. For ?v12=1 we observe only transitions with ?K=±1, and for ?v12=2 we observe only ?K=0. We present a Franck-Condon model to explain these apparent selection rules and the overall pattern of intensity.

Rueda, D.; Boyarkin, O. V.; Rizzo, T. R.; Mukhopadhyay, I.; Perry, D. S.

2002-01-01

255

Ab Initio Determination of the Roto-Torsional Energy Levels of trans-1,3-Butadiene.  

PubMed

In this paper, the flexible model based on relaxed ab initio calculations, which has been several times employed for vibrational calculations, is extended to the analysis of the rotational structures starting by the roto-torsional bands of trans-1,3-butadiene. For this purpose, the potential energy surface and the kinetic energy parameters of the nu13 vibrational mode of butadiene are obtained with the Möller-Plesset perturbation theory up to the second order and the 6-31G(d, p), 6-31G(df, p), 6-311G(d, p), 6-311G(df, p), and 6-311G(df, pd) basis sets. The torsional levels of the -h6, -d4, and -d6 isotopic species are calculated variationally and are compared with experimental data. It may be concluded that the one-dimensional model appears sufficiently accurate for butadiene-h6 and -d4, whereas a large kinetic interaction with the lowest wagging mode is observed for butadiene-d6. The rotational levels corresponding to the first vibrational states of the -h6 and -d4 species are determined variationally up to J = 17 and J = 11 from the ab initio spectroscopic parameters which have been expanded as functions of the torsional coordinate using symmetry adapted series. The torsional wavefunction is contracted to reduce the size of the Hamiltonian matrix. A good agreement with the observed transitions is obtained for the first states v = 0 and v = 1. As is expected, the K doubling obtained is relatively small. For this reason, the quartic and sextic centrifugal distortion constants are obtained from the least-square fit of the variational levels to the perturbation theory equations for the symmetric top. Copyright 1998 Academic Press. PMID:9753561

Senent

1998-10-01

256

Observation of Orbital Angular Momentum Sidebands due to Optical Reflection  

NASA Astrophysics Data System (ADS)

We investigate how the orbital angular momentum of a paraxial light beam is affected upon reflection at a planar interface. Theoretically, the unavoidable angular spread of the beam leads to orbital angular momentum sidebands, which are found to be already significant for a modest beam spread (0.05). In analogy to the polarization Fresnel coefficients, we develop an analytical theory based upon spatial Fresnel coefficients; this allows a straightforward prediction of the strength of the sidebands. We confirm this by experiment and numerical simulation.

Löffler, W.; Aiello, Andrea; Woerdman, J. P.

2012-09-01

257

Modelling black holes with angular momentum in loop quantum gravity  

NASA Astrophysics Data System (ADS)

We construct a connection formulation of Kerr isolated horizons. As in the non-rotating case, the model is based on a Chern-Simons theory describing the degrees of freedom on the horizon. The presence of a non-vanishing angular momentum modifies the admissibility conditions for spin network states. Physical states of the system are in correspondence with open intertwiners with total spin matching the angular momentum of the spacetime.

Frodden, Ernesto; Perez, Alejandro; Pranzetti, Daniele; Röken, Christian

2014-12-01

258

Angular Momentum Transport in Circumplanetary Disks  

NASA Astrophysics Data System (ADS)

The Galilean satellites likely formed in a late-stage accretion disk that persisted around Jupiter after it was fully formed. The structure of this disk is highly dependent on its ability to transport angular momentum. Uncertainty in the level of angular momentum transport has led to competing theories of circumplanetary disk structure. Despite success in other astrophysical contexts, recent studies indicate that the conditions were not suitable for magnetorotational instabilities to develop in circumplanetary disks. However, it has been suggested that baroclinic instabilities can generate turbulence and provide the necessary transport of angular momentum. We present a 1+1D numerical model of the circumplanetary accretion disk that surrounded Jupiter during the epoch of regular satellite formation. An analysis of the radial entropy gradient in this model indicates that baroclinic instabilities can not only develop but persist throughout the majority of the disk. Furthermore, we find evidence for a two-component, gas-starved disk which may help to reconcile the differences in current competing theories of circumplanetary disk structure.

Mitchell, Tyler R.

2014-11-01

259

Carbon nanotube fibers as torsion sensors  

NASA Astrophysics Data System (ADS)

Carbon nanotube fibers possess the ability to respond electrically to tensile loading. This research explores their electrical response to torsional loading; results demonstrate that applied twist compacts the fiber, resulting in increased electrical contact between carbon nanotubes. Shear strains in excess of 24% do not result in permanent changes in electrical resistance along uninfused fibers, while irreversible changes in electrical resistance arise from applied shear strains of 12.9% in epoxy infused fibers. Bulk shear modulus is approximated to be 0.40 ± 0.02 GPa for unreinforced and 2.79 ± 0.64 GPa for infused fibers.

Wu, A. S.; Nie, X.; Hudspeth, M. C.; Chen, W. W.; Chou, T.-W.; Lashmore, D. S.; Schauer, M. W.; Towle, E.; Rioux, J.

2012-05-01

260

Surgical correction of idiopathic medical femoral torsion.  

PubMed

We reviewed 28 hips in 14 patients with severe bilateral idiopathic medial femoral torsion which had been corrected by intertrochanteric rotation osteotomy using crossed pins for fixation and a hip spica. There were 10 girls and 4 boys with a mean age of 7 years and 9 months. All had functional and cosmetic disability before operation. The average follow up was for 3 years and 9 months. Full correction was achieved in 27 hips. In one partial avascular necrosis of the femoral head occurred one year after operation and was treated by an acetabular augmentation procedure with a satisfactory outcome. PMID:8557417

Shim, J S; Staheli, L T; Holm, B N

1995-01-01

261

Torsional fatigue tests of anodized aluminum rods  

Microsoft Academic Search

Fatigue tests in reversed torsion were run on 2024-T351 aluminum-alloy specimens in (1) uncoated state and (2) anodized with\\u000a 0.3 and 0.05-mil (0.0076- and 0.0013-mm) coatings. Tests on both groups were run at low (20–25 percent), medium (55–60 percent),\\u000a and high (86–91 percent) relative humidity. One lot of uncoated specimens was tested that had been polished after machining,\\u000a and one

E. F. Womack; J. H. Wilson; H. H. Mabie

1976-01-01

262

Laboratory Tests of Gravitational Physics Using a Cryogenic Torsion Pendulum  

NASA Astrophysics Data System (ADS)

Progress and plans are reported for a program of gravitational physics experiments using cryogenic torsion pendula undergoing large amplitude torsional oscillation. The program includes a UC Irvine project to measure the gravitational constant G and joint UC Irvine-U. Washington projects to test the gravitational inverse square law at a range of about 10 cm and to test the weak equivalence principle.

Berg, E. C.; Bantel, M. K.; Cross, W. D.; Inoue, T.; Newman, R. D.; Steffen, J. H.; Moore, M. W.; Boynton, P. E.

2006-02-01

263

Modal analysis techniques for torsional vibration of diesel crankshafts  

Microsoft Academic Search

Torsional vibration in diesel engines, creates a potentially dangerous condition in that there may be no visible or audible indication of its existence, but catastrophic shaft fatigue failure can result. Classical methodology for torsional vibration analysis is cumbersome to employ and provides limited useful information. A methodology is presented which allows a quick and complete analysis of vibratory stress in

P. J. Carrato; C. C. Fu

1986-01-01

264

Precision piezoelectric stepping motor using piezoelectric torsional actuator  

NASA Astrophysics Data System (ADS)

This paper deals with a newly developed piezoelectric motor that generates precise stepping motion using a piezoelectric torsional actuator and a pair of one-way clutch bearings. The torsional actuator consists of a piezoelectric cylinder that produces rotation motion invoking shear mode of piezoelectric materials and a torsion bar that magnifies the rotation angle produced from the piezoelectric cylinder. Inner one-way clutch bearing is fit on the torsion bar and outer bearing is mounted outside of the inner bearing such that when the torsion bar rotates in one direction, the inner bearing moves together while the outer one slips. When the torsion bar rotates in opposite direction, the inner bearing slips against the torsion bar while the outer bearing locks the inner bearing so as to accumulate the rotation angle. Because the elaborate piezoelectric torsional actuator functions as the driving source at high frequency, a precise step motion with high speed can be produced. The optimum condition for driving the motor is investigated in terms of excitation frequency, electrical impedance and the location of the bearing set. The rotation speed and torque of the motor is investigated, and 350 rpm and 0.19mNm torque are observed in maximum.

Kang, Byung-Woo; Kim, Jaehwan; Cheong, ChaeCheon; Yang, Bo-Won

2001-03-01

265

TORSIONAL VIBRATION REDUCTION IN INTERNAL COMBUSTION ENGINES USING CENTRIFUGAL PENDULUMS  

Microsoft Academic Search

The goal of the present work is to investigate the performance of tautochronic centrifugal pendulum vibration absorbers (CPVA's) for reducing torsional vibration in internal combustion engines. A mathematical model is first built for the torsional dynamics of an in- line, four-stroke, four-cylinder engine, including the consideration of inertia effects of connecting rods and pistons, gas pressure inside the cylinder chambers,

Cheng-Tang Lee; Steven W. Shaw

266

Five Year Retrospective Case Series of Adnexal Torsion  

PubMed Central

Aims and Objectives: Adnexal torsion is a rare gynaecological emergency that requires an early surgical intervention to save the adnexa from irreversible damage .Our study is about clinical presentation and management approach of adnexal torsion in a tertiary care centre. Study Design: Retrospective study. Materials and Methods: Review of case records during the five years of 2008 November -2013 November in Amrita Institute of Medical Sciences, Kochi, India. Results: Adnexal torsion was found mainly in the reproductive age. Ultrasound was the most commonly used imaging modality. Benign tumours predispose to torsion. Torsion occurred during postovulatory period in many cases. Polycystic ovaries were a risk factor for unexplained torsion in younger age groups. Diagnosis of adnexal torsion was mostly intra operative by direct visualisation of the rotated adnexa. Laparoscopy was the preferred method of surgical intervention. Ovarian conservation was tried in majority of the child bearing age groups. Conclusion: Adnexal torsion is a rare emergency which requires a high index of clinical suspicion for diagnosis as the symptoms are non specific. Imaging helps in diagnosis but most of them are diagnosed intra operatively. Laparoscopic conservative surgery is the preferred surgical approach especially in younger age groups. An early surgical intervention helps in salvaging the adnexa and prevents further complications.

Joy, Smitha; Nayar, Jayashree

2014-01-01

267

Spontaneous nerve torsion: unusual cause of radial nerve palsy.  

PubMed

Spontaneous nerve torsion is a rare cause of nerve palsy. We describe a case of nerve torsion affecting the radial nerve in order to inform radiologists of the existence of this condition and subtle features on cross-sectional imaging that can suggest the diagnosis preoperatively. PMID:25244923

Endo, Yoshimi; Miller, Theodore T; Carlson, Erik; Wolfe, Scott W

2015-03-01

268

Ultrahigh Torsional Stiffness and Strength of Boron Nitride Jonathan Garel,  

E-print Network

Ultrahigh Torsional Stiffness and Strength of Boron Nitride Nanotubes Jonathan Garel, Itai Leven of boron nitride nanotube (BNNT) torsional mechanics. We show that BNNTs exhibit a much stronger mechanical in nanoelectromechanical systems (NEMS), fibers, and nanocomposites. KEYWORDS: Nanotube, boron nitride (BN), atomic force

Hod, Oded

269

An assessment of Evans' unified field theory II  

E-print Network

Evans developed a classical unified field theory of gravitation and electromagnetism on the background of a spacetime obeying a Riemann-Cartan geometry. In an accompanying paper I, we analyzed this theory and summarized it in nine equations. We now propose a variational principle for Evans' theory and show that it yields two field equations. The second field equation is algebraic in the torsion and we can resolve it with respect to the torsion. It turns out that for all physical cases the torsion vanishes and the first field equation, together with Evans' unified field theory, collapses to an ordinary Einstein equation.

Friedrich W. Hehl; Yuri N. Obukhov

2007-03-10

270

Angular control of optical cavities in a radiation pressure dominated regime: the Enhanced LIGO case  

E-print Network

We describe the angular sensing and control of the 4 km detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO). The culmination of first generation LIGO detectors, Enhanced LIGO operated between 2009 and 2010 with about 40 kW of laser power in the arm cavities. In this regime, radiation pressure effects are significant and induce instabilities in the angular opto-mechanical transfer functions. Here we present and motivate the angular sensing and control (ASC) design in this extreme case and present the results of its implementation in Enhanced LIGO. Highlights of the ASC performance are: successful control of opto-mechanical torsional modes, relative mirror motions of 1x10^{-7} rad rms, and limited impact on in-band strain sensitivity.

Dooley, Katherine L; Adhikari, Rana X; Evans, Matthew; Fricke, Tobin T; Fritschel, Peter; Frolov, Valera; Kawabe, Keita; Smith-Lefebvre, Nicolás

2013-01-01

271

Bulk angular momentum and Hall viscosity in chiral superconductors  

NASA Astrophysics Data System (ADS)

We establish the Berry-phase formulas for the angular momentum (AM) and the Hall viscosity (HV) to investigate chiral superconductors (SCs) in two and three dimensions. The AM is defined by the temporal integral of the antisymmetric momentum current induced by an adiabatic deformation, while the HV is defined by the symmetric momentum current induced by the symmetric torsional electric field. Without suffering from the system size or geometry, we obtain the macroscopic AM Lz=?mN0/2 at zero temperature in full-gap chiral SCs, where m is the magnetic quantum number and N0 is the total number of electrons. We also find that the HV is equal to half the AM at zero temperature not only in full-gap chiral SCs as is well known but also in nodal ones, but its behavior at finite temperature is different in the two cases.

Shitade, Atsuo; Kimura, Taro

2014-10-01

272

Krukenberg Tumor: A Rare Cause of Ovarian Torsion  

PubMed Central

Ovarian torsion is the fifth most common gynecological surgical emergency. Ovarian torsion is usually associated with a cyst or a tumor, which is typically benign. The most common is mature cystic teratoma. We report the case of a 43-year-old woman who came to the Emergency Department with rare acute presentation of bilateral Krukenberg tumors, due to unilateral ovarian torsion. In this case report, we highlight the specific computed tomography (CT) features of ovarian torsion and demonstrate the unique radiological findings on CT imaging. Metastasis to the ovary is not rare and 5 to 10% of all ovarian malignancies are metastatic. The stomach is the common primary site in most Krukenberg tumors (70%); an acute presentation of metastatic Krukenberg tumors with ovarian torsion is rare and not previously reported in radiology literature. PMID:22439130

Sandhu, Sameer; Arafat, Omar; Patel, Harshad; Lall, Chandana

2012-01-01

273

Infrared modified gravity with dynamical torsion  

SciTech Connect

We continue the recent study of the possibility of constructing a consistent infrared modification of gravity by treating the vierbein and connection as independent dynamical fields. We present the generalized Fierz-Pauli equation that governs the propagation of a massive spin-2 mode in a model of this sort in the backgrounds of arbitrary torsionless Einstein manifolds. We show explicitly that the number of propagating degrees of freedom in these backgrounds remains the same as in flat space-time. This generalizes the recent result that the Boulware-Deser phenomenon does not occur in de Sitter and anti-de Sitter backgrounds. We find that, at least for weakly curved backgrounds, there are no ghosts in the model. We also discuss the interaction of sources in flat background. It is generally believed that the spinning matter is the only source of torsion. Our flat space study shows that this is not the case. We demonstrate that an ordinary conserved symmetric energy-momentum tensor can also generate torsion fields and thus excite massive spin-2 degrees of freedom.

Nikiforova, V. [Physics Department, Moscow State University, Moscow, 119899 (Russian Federation); Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, Moscow, 117312 (Russian Federation); Randjbar-Daemi, S. [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, I-34014, Trieste (Italy); Rubakov, V. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, Moscow, 117312 (Russian Federation)

2009-12-15

274

Stem torsion in total hip replacement  

PubMed Central

Background and purpose The clinical results of THR may be improved by correct femoral torsion. We evaluated the stem position by postoperative CT examination in 60 patients. Methods 60 patients requiring total hip arthroplasty were prospectively enrolled in this study. Minimally invasive THR was performed (anterior approach) in a lateral decubitus position and each patient underwent a postoperative CT examination. The position of the stem was evaluated by an independent external institution. Results Stem torsion ranged from –19° retrotorsion to 33° antetorsion. Normal antetorsion (i.e 10–15° according to Tönnis) was present in 5 of 60 patients, so the prevalence of abnormal stem antetorsion was 92% (95% CI: 82–97). We found a stem antetorsion outside the range of 0–25° in 21 of 60 hips. Women had a higher mean stem antetorsion (8.0° (SD 11)) than men (1.5° (SD 10)). Interpretation Postoperative stem antetorsion shows a high variability and is gender-related. We suggest precise assessment of stem antetorsion intraoperatively by means of computer navigation, preparing the femur first. In abnormal stem antetorsion, the cup position can be adjusted using a combined anteversion concept; alternatively, modular femoral components or stems with retroverted or anteverted necks (“retrostem”) could be used. PMID:20919811

2010-01-01

275

PREDICTED EFFECTS OF LOCAL CONFORMATIONAL COUPLING AND EXTERNAL RESTRAINTS ON THE TORSIONAL PROPERTIES OF SINGLE DNA MOLECULES*  

PubMed Central

A newly developed, coarse-grained treatment of the low-frequency normal modes of DNA has been adapted to study the torsional properties of fully extended, double-helical molecules. Each base pair is approximated in this scheme as a rigid body, and molecular structure is described in terms of the relative position and orientation of successive base pairs. The torsional modulus C is computed from the lowest-frequency normal twisting mode using expressions valid for a homogeneous, naturally straight elastic rod. Fluctuations of local dimeric structure, including the coupled variation of conformational parameters, are based on the observed arrangements of neighboring base pairs in high-resolution structures. Chain ends are restrained by an elastic energy term. The calculations show how the end-to-end constraints placed on a naturally straight DNA molecule, in combination with the natural conformational features of the double helix, can account for the substantially larger torsional moduli determined with state-of-the-art, single-molecule experiments compared to values extracted from solution measurements and/or incorporated into theories to account for the force-extension properties of single molecules. The computed normal-mode frequencies and torsional moduli increase substantially if base pairs are inclined with respect to the double-helical axis and the deformations of selected conformational variables follow known interdependent patterns. The changes are greatest if the fluctuations in dimeric twisting are coupled with parameters that directly alter the end-to-end displacement. Imposed restraints that mimic the end-to-end conditions of single-molecule experiments then impede the twisting of base pairs and increase the torsional modulus. The natural inclination of base pairs concomitantly softens the Young’s modulus, i.e., ease of duplex stretching. The analysis of naturally curved DNA points to a drop in the torsional modulus upon imposed extension of the double-helical molecule. PMID:19081755

MATSUMOTO, ATSUSHI; OLSON, WILMA K.

2008-01-01

276

Torsional ARC Effectively Expands the Visual Field in Hemianopia  

PubMed Central

Purpose Exotropia in congenital homonymous hemianopia has been reported to provide field expansion that is more useful when accompanied with harmonios anomalous retinal correspondence (HARC). Torsional strabismus with HARC provides a similar functional advantage. In a subject with hemianopia demonstrating a field expansion consistent with torsion we documented torsional strabismus and torsional HARC. Methods Monocular visual fields under binocular fixation conditions were plotted using a custom dichoptic visual field perimeter (DVF). The DVF was also modified to measure perceived visual directions under dissociated and associated conditions across the central 50° diameter field. The field expansion and retinal correspondence of a subject with torsional strabismus (along with exotropia and right hypertropia) with congenital homonymous hemianopia was compared to that of another exotropic subject with acquired homonymous hemianopia without torsion and to a control subject with minimal phoria. Torsional rotations of the eyes were calculated from fundus photographs and perimetry. Results Torsional ARC documented in the subject with congenital homonymous hemianopia provided a functional binocular field expansion up to 18°. Normal retinal correspondence was mapped for the full 50° visual field in the control subject and for the seeing field of the acquired homonymous hemianopia subject, limiting the functional field expansion benefit. Conclusions Torsional strabismus with ARC, when occurring with homonymous hemianopia provides useful field expansion in the lower and upper fields. Dichoptic perimetry permits documentation of ocular alignment (lateral, vertical and torsional) and perceived visual direction under binocular and monocular viewing conditions. Evaluating patients with congenital or early strabismus for HARC is useful when considering surgical correction, particularly in the presence of congenital homonymous hemianopia. PMID:22885782

Satgunam, PremNandhini; Peli, Eli

2012-01-01

277

Intrinsic Angular Momentum of Light.  

ERIC Educational Resources Information Center

Derives a familiar torque-angular momentum theorem for the electromagnetic field, and includes the intrinsic torques exerted by the fields on the polarized medium. This inclusion leads to the expressions for the intrinsic angular momentum carried by the radiation traveling through a charge-free medium. (Author/MA)

Santarelli, Vincent

1979-01-01

278

Angular momentum in human walking  

Microsoft Academic Search

SUMMARY Angular momentum is a conserved physical quantity for isolated systems where no external moments act about a body?s center of mass (CM). However, in the case of legged locomotion, where the body interacts with the environment (ground reaction forces), there is no a priori reason for this relationship to hold. A key hypothesis in this paper is that angular

Hugh Herr; Marko Popovic

2008-01-01

279

The Angular Gyrus  

PubMed Central

There is considerable interest in the structural and functional properties of the angular gyrus (AG). Located in the posterior part of the inferior parietal lobule, the AG has been shown in numerous meta-analysis reviews to be consistently activated in a variety of tasks. This review discusses the involvement of the AG in semantic processing, word reading and comprehension, number processing, default mode network, memory retrieval, attention and spatial cognition, reasoning, and social cognition. This large functional neuroimaging literature depicts a major role for the AG in processing concepts rather than percepts when interfacing perception-to-recognition-to-action. More specifically, the AG emerges as a cross-modal hub where converging multisensory information is combined and integrated to comprehend and give sense to events, manipulate mental representations, solve familiar problems, and reorient attention to relevant information. In addition, this review discusses recent findings that point to the existence of multiple subdivisions in the AG. This spatial parcellation can serve as a framework for reporting AG activations with greater definition. This review also acknowledges that the role of the AG cannot comprehensibly be identified in isolation but needs to be understood in parallel with the influence from other regions. Several interesting questions that warrant further investigations are finally emphasized. PMID:22547530

2013-01-01

280

Torsional velocity measurements in wire, with application to metal-matrix composites  

NASA Astrophysics Data System (ADS)

A technique is described for measuring torsional wave velocity in (nonferromagnetic) wire with diameters of less than 1 mm. Transduction is noncontacting, via Lorentz forces acting across a gap between transducer and wire, so that velocity can be ''scanned'' along the length of the wire. A double-receiver approach permits the scan to be made in a ''point-by-point'' fashion. The wires are a metal-matrix composite of 6061 aluminum and pitch mesophase graphite. Some data are presented, together with a discussion of the effects of metal-matrix-composite parameters, such as graphite content and porosity, on torsional velocity. An extrapolation of our metal-matrix- composite data yields a value for c44, of the graphite fiber, that was within 1% of a value determined from data of Fischbach and Scrinivasagopalan. Good predictions of experimental results were obtained through use of theory of Hashin and of Achenbach and Herrmann. Some differences, and their implications, between torsional and longitudinal waves propagating in metal-matrix-composite wire are described.

Frost, H. M.; Prout, J. H.; Reed, Robert W.

1982-06-01

281

Multistep-shaping control based on the static and dynamic behavior of nonlinear optical torsional micromirror  

NASA Astrophysics Data System (ADS)

Electrostatically driven torsional micromirrors are suitable for optical microelectromechanical systems due to their good dynamic response, low adhesion, and simple structure for large-scale-integrated applications. For these devices, how to eliminate the excessive residual vibration in order to achieve more accurate positioning and faster switching is an important research topic. Because of the known nonlinearity issues, traditional shaping techniques based on linear theories are not suitable for nonlinear torsional micromirrors. In addition, due to the difficulties in calculating energy dissipation, the existing nonlinear command shaping techniques using energy method have neglected the effect of damping. We analyze the static and dynamic behavior of the electrostatically actuated torsional micromirrors. Based on the response of these devices, a multistep-shaping control considering the damping effects and the nonlinearity is proposed. Compared to the conventional closed-loop control, the proposed multistep-shaping control is a feedforward approach which can yield a good enough performance without extra sensors and actuators. Simulation results show that, without changing the system structure, the preshaping input reduces the settling time from 4.3 to 0.97 ms, and the overshoot percentage of the mirror response is decreased from 33.2% to 0.2%.

Bai, Cheng; Huang, Jin

2014-05-01

282

Detecting the crankshaft torsional vibration of diesel engines for combustion related diagnosis  

NASA Astrophysics Data System (ADS)

Early fault detection and diagnosis for medium-speed diesel engines is important to ensure reliable operation throughout the course of their service. This work presents an investigation of the diesel engine combustion related fault detection capability of crankshaft torsional vibration. The encoder signal, often used for shaft speed measurement, has been used to construct the instantaneous angular speed (IAS) waveform, which actually represents the signature of the torsional vibration. Earlier studies have shown that the IAS signal and its fast Fourier transform (FFT) analysis are effective for monitoring engines with less than eight cylinders. The applicability to medium-speed engines, however, is strongly contested due to the high number of cylinders and large moment of inertia. Therefore the effectiveness of the FFT-based approach has further been enhanced by improving the signal processing to determine the IAS signal and subsequently tested on a 16-cylinder engine. In addition, a novel method of presentation, based on the polar coordinate system of the IAS signal, has also been introduced; to improve the discrimination features of the faults compared to the FFT-based approach of the IAS signal. The paper discusses two typical experimental studies on 16- and 20-cylinder engines, with and without faults, and the diagnosis results by the proposed polar presentation method. The results were also compared with the earlier FFT-based method of the IAS signal.

Charles, P.; Sinha, Jyoti K.; Gu, F.; Lidstone, L.; Ball, A. D.

2009-04-01

283

The laboratory millimeter-wave spectrum of methyl formate in its ground torsional E state  

NASA Technical Reports Server (NTRS)

Over 250 rotational transitions of the internal rotor methyl formate (HCOOCH3) in its ground v(t) = 0 degenerate (E) torsional substate have been measured in the millimeter-wave spectral region. These data and a number of E-state lines identified by several other workers have been analyzed using an extension of the classical principal-axis method in the high barrier limit. The resulting rotational constants allow accurate prediction of the v(t) = 0 E substate methyl formate spectrum below 300 GHz between states with angular momentum J not greater than 30 and rotational energy of not more than 350/cm. The calculated transition frequencies for the E state, when combined with the results of the previous analysis of the ground-symmetric, nondegenerate state, account for over 200 of the emission lines observed toward Orion in a recent survey of the 215-265 GHz band.

Plummer, G. M.; Herbst, E.; De Lucia, F. C.; Blake, G. A.

1986-01-01

284

Exact solutions for the flow of second grade fluid in annulus between torsionally oscillating cylinders  

NASA Astrophysics Data System (ADS)

The velocity field and the associated shear stress corresponding to the torsional oscillatory flow of a second grade fluid, between two infinite coaxial circular cylinders, are determined by means of the Laplace and Hankel transforms. At time t = 0, the fluid and both the cylinders are at rest and at t = 0+, cylinders suddenly begin to oscillate around their common axis in a simple harmonic way having angular frequencies ?1 and ?2. The obtained solutions satisfy the governing differential equation and all imposed initial and boundary conditions. The solutions for the motion between the cylinders, when one of them is at rest, can be obtained from our general solutions. Furthermore, the corresponding solutions for Newtonian fluid are also obtained as limiting cases of our general solutions.

Mahmood, Amir; Parveen, Saima; Khan, Najeeb Alam

2011-04-01

285

Pearls and pitfalls in diagnosis of ovarian torsion.  

PubMed

Ovarian torsion is defined as partial or complete rotation of the ovarian vascular pedicle and causes obstruction to venous outflow and arterial inflow. Ovarian torsion is usually associated with a cyst or tumor, which is typically benign; the most common is mature cystic teratoma. Ultrasonography (US) is the primary imaging modality for evaluation of ovarian torsion. US features of ovarian torsion include a unilateral enlarged ovary, uniform peripheral cystic structures, a coexistent mass within the affected ovary, free pelvic fluid, lack of arterial or venous flow, and a twisted vascular pedicle. The presence of flow at color Doppler imaging does not allow exclusion of torsion but instead suggests that the ovary may be viable, especially if flow is present centrally. Absence of flow in the twisted vascular pedicle may indicate that the ovary is not viable. The role of computed tomography (CT) has expanded, and it is increasingly used in evaluation of abdominal pain. Common CT features of ovarian torsion include an enlarged ovary, uterine deviation to the twisted side, smooth wall thickening of the twisted adnexal cystic mass, fallopian tube thickening, peripheral cystic structures, and ascites. Understanding the imaging appearance of ovarian torsion will lead to conservative, ovary-sparing treatment. PMID:18794312

Chang, Hannah C; Bhatt, Shweta; Dogra, Vikram S

2008-01-01

286

Laparoscopic management of pedicle torsion of adnexal cysts.  

PubMed

Pedicle torsion of adnexal cysts results from the increased weight of cysts, longer length of the ovarian and suspensory ligaments or ovarian teratoma. Color doppler ultrasonography is particularly important for detecting suspected cyst torsion. Laparoscopy is becoming more important in the early diagnosis and treatment of adnexal cyst torsion due to its advantages, such as its minimally invasive nature, reduced acute stress reaction and facilitation of direct observation of intra-abdominal lesions. The present study analyzed 28 cases of laparoscopic torsion surgery. The laparoscopic conservative surgery rate was 75% and loss of endocrine function and fertility was avoided. Since the torsion duration is the only variable factor for avoiding oophorectomy, laparoscopic exploration should be performed as soon as possible when pedicle torsion of an adnexal cyst is suspected. Detorsion while retaining ovarian function did not increase the risk of thromboembolism and laparoscopic surgery was minimally invasive with faster recovery times and minimal impact on fertility. Furthermore, the study showed that the laparoscopic management of pedicle torsion of adnexal cysts is safe and reliable with the retention of ovarian endocrine and reproductive function. PMID:23761838

Wang, Yuxia; Xie, Yuanyuan; Wu, Xiaoqing; Li, Lu; Ma, Yifei; Wang, Xiaoyuan

2013-05-01

287

Torsion of the Left Ventricle During Pacing with MRI Tagging  

PubMed Central

The effects of different pacing protocols on left ventricular (LV) torsion were evaluated over the full cardiac cycle. A systolic and diastolic series of magnetic resonance imaging (MRI) scans were combined and used to calculate the torsion of the LV in a canine model. The asynchronous activation resulting from ventricular pacing interferes with the temporal evolution of LV torsion. The torsion of the left ventricle was investigated under three different protocols: 1) right atrial pacing, 2) right ventricular pacing, and 3) simultaneous pacing from the right ventricular apex and LV base. The temporal evolution of torsion was determined from tagged MRI and evaluated over the cardiac cycle. The peak rotation for the atrially paced hearts was 11.1° (±3.5°) compared to 6.1° (±1.7°) and 6.1° (±0.7°) for those hearts paced from the right ventricle and from both ventricles, respectively. While biventricular pacing increases the synchrony of contraction, it significantly alters the pattern of LV torsion. From these experiments we have shown that measuring torsion is an extremely sensitive indicator of the existence of ectopic excitation. PMID:14664130

Sorger, Jonathan M.; Wyman, Bradley T.; Faris, Owen P.; Hunter, William C.; McVeigh, Elliot R.

2007-01-01

288

Smoothed dissipative particle dynamics with angular momentum conservation  

NASA Astrophysics Data System (ADS)

Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPD formulation (SDPD+a) is directly derived from the Navier-Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor-Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.

Müller, Kathrin; Fedosov, Dmitry A.; Gompper, Gerhard

2015-01-01

289

Torsion constraints from cosmological magnetic field and QCD domain walls  

NASA Astrophysics Data System (ADS)

Earlier Kostelecky [Phys. Rev. D 69, 105009 (2004)] has investigated the role of gravitational sector in Riemann-Cartan (RC) spacetime with torsion, in Lorentz and CPT violating (LV) Standard Model extension (SME). In his paper use of quantum electrodynamic (QED) extension in RC spacetime is made. More recently L. C. Garcia de Andrade [Phys. Lett. B 468, 28 (2011)] obtained magnetic field galactic dynamo seeds in the bosonic sector with massless photons, which proved to decay faster than necessary [Phys. Lett. B 711, 143 (2012)] to be able to seed galactic dynamos. In this paper it is shown that by using the fermionic sector of Kostelecky-Lagrangian and torsion written as a chiral current, one obtains torsion and magnetic fields explicitly from a Heisenberg-Ivanenko form of Dirac equation whose solution allows us to express torsion in terms of LV coefficients and magnetic field in terms of fermionic matter fields. When minimal coupling between electromagnetic and torsion fields is used it is shown that the fermionic sector of QED with torsion leads to resonantly amplify magnetic fields which mimics an ?2-dynamo mechanism. Fine-tuning of torsion is shown to result in the dynamo reversal, a phenomenon so important in solar physics and geophysics. Of course this is only an analogy since torsion is very weak in solar and geophysics contexts. An analogous expression for the ?-effect of mean-field dynamos is also obtained where the ?-effect is mimic by torsion. Similar resonant amplification mechanisms connected to early universe have been considered by Finelli and Gruppuso.

Garcia de Andrade, L. C.

2014-10-01

290

Localized Torsional Tension in the DNA of Human Cells  

NASA Astrophysics Data System (ADS)

Torsional tension in DNA may be both a prerequisite for the efficient initiation of transcription and a consequence of the transcription process itself with the generation of positive torsional tension in front of the RNA polymerase and negative torsional tension behind it. To examine torsional tension in specific regions of genomic DNA in vivo, we developed an assay using photoactivated psoralen as a probe for unconstrained DNA superhelicity and x-rays as a means to relax DNA. Psoralen intercalates more readily into DNA underwound by negative torsional tension than into relaxed DNA, and it can form interstrand DNA cross-links upon UVA irradiation. By comparing the amount of psoralen-induced DNA cross-links in cells irradiated with x-rays either before or after the psoralen treatment, we examined the topological state of the DNA in specific regions of the genome in cultured human 6A3 cells. We found that although no net torsional tension was detected in the bulk of the genome, localized tension was prominent in the DNA of two active genes. Negative torsional tension was found in the 5' end of the amplified dihydrofolate reductase gene and in a region near the 5' end of the 45S rRNA transcription unit, whereas a low level of positive torsional tension was found in a region near the 3' end of the dihydrofolate reductase gene. These results document an intragenomic heterogeneity of DNA torsional tension and lend support to the twin supercoiled domain model for transcription in the genome of intact human cells.

Ljungman, Mats; Hanawalt, Philip C.

1992-07-01

291

Theories  

NSDL National Science Digital Library

This activity is designed to help building student understanding of how scientific theories can change over time. Science theories change in the face of new evidence. However, when new explanatory frameworks, or theories, are proposed to explain scientific phenomena, there is often a lengthy period during which groups of scientists use different competing theories to explain the same phenomena. During the activity, students are introduced to the geocentric and heliocentric models, students compare the two models, and then observe the time it took to change the theory underpinning the heliocentric model. This activity is part of the "Swift: Eyes through Time" collection that is available on the Teacher's Domain website.

292

Torsional suspension system for testing space structures  

NASA Technical Reports Server (NTRS)

A low frequency torsional suspension system for testing a space structure uses a plurality of suspension stations attached to the space structure along the length thereof in order to suspend the space structure from an overhead support. Each suspension station includes a disk pivotally mounted to the overhead support, and two cables which have upper ends connected to the disk and lower ends connected to the space structure. The two cables define a parallelogram with the center of gravity of the space structure being vertically beneath the pivot axis of the disk. The vertical distance between the points of attachment of the cables to the disk and the pivot axis of the disk is adjusted to lower the frequency of the suspension system to a level which does not interfere with frequency levels of the space structure, thereby enabling accurate measurement.

Reed, Wilmer H., III (inventor); Gold, Ronald R. (inventor)

1991-01-01

293

Torsional ultrasonic transducer computational design optimization.  

PubMed

A torsional piezoelectric ultrasonic sensor design is proposed in this paper and computationally tested and optimized to measure shear stiffness properties of soft tissue. These are correlated with a number of pathologies like tumors, hepatic lesions and others. The reason is that, whereas compressibility is predominantly governed by the fluid phase of the tissue, the shear stiffness is dependent on the stroma micro-architecture, which is directly affected by those pathologies. However, diagnostic tools to quantify them are currently not well developed. The first contribution is a new typology of design adapted to quasifluids. A second contribution is the procedure for design optimization, for which an analytical estimate of the Robust Probability Of Detection, called RPOD, is presented for use as optimality criteria. The RPOD is formulated probabilistically to maximize the probability of detecting the least possible pathology while minimizing the effect of noise. The resulting optimal transducer has a resonance frequency of 28 kHz. PMID:24882020

Melchor, J; Rus, G

2014-09-01

294

Mutations in GNAL cause primary torsion dystonia.  

PubMed

Dystonia is a movement disorder characterized by repetitive twisting muscle contractions and postures. Its molecular pathophysiology is poorly understood, in part owing to limited knowledge of the genetic basis of the disorder. Only three genes for primary torsion dystonia (PTD), TOR1A (DYT1), THAP1 (DYT6) and CIZ1 (ref. 5), have been identified. Using exome sequencing in two families with PTD, we identified a new causative gene, GNAL, with a nonsense mutation encoding p.Ser293* resulting in a premature stop codon in one family and a missense mutation encoding p.Val137Met in the other. Screening of GNAL in 39 families with PTD identified 6 additional new mutations in this gene. Impaired function of several of the mutants was shown by bioluminescence resonance energy transfer (BRET) assays. PMID:23222958

Fuchs, Tania; Saunders-Pullman, Rachel; Masuho, Ikuo; Luciano, Marta San; Raymond, Deborah; Factor, Stewart; Lang, Anthony E; Liang, Tsao-Wei; Trosch, Richard M; White, Sierra; Ainehsazan, Edmond; Hervé, Denis; Sharma, Nutan; Ehrlich, Michelle E; Martemyanov, Kirill A; Bressman, Susan B; Ozelius, Laurie J

2013-01-01

295

Gravitational Stability of inflaton and torsion in Einstein-Cartan-Klein-Gordon cosmology with kinky potentials  

E-print Network

Gravitational stability of torsion and inflaton field in a four-dimensional spacetime de Sitter solution in scalar-tensor cosmology where Cartan torsion propagates is investigated in detail. Inflaton and torsion evolution equations are derived by making use of a Lagrangean method. Stable and unstable modes for torsion and inflatons are found to be dependent of the background torsion and inflaton fields. Present astrophysical observations favour a stable mode for torsion since this would explain why no relic torsion imprint has been found on the Cosmic Background Radiation in the universe.

L. C. Garcia de Andrade

2002-01-21

296

Torsion and noninertial effects on a nonrelativistic Dirac particle  

NASA Astrophysics Data System (ADS)

We investigate torsion and noninertial effects on a spin-1/2 quantum particle in the nonrelativistic limit of the Dirac equation. We consider the cosmic dislocation spacetime as a background and show that a rotating system of reference can be used out to distances which depend on the parameter related to the torsion of the defect. Therefore, we analyse torsion effects on the spectrum of energy of a nonrelativistic Dirac particle confined to a hard-wall potential in a Fermi-Walker reference frame.

Bakke, K.

2014-07-01

297

Discussion on massive gravitons and propagating torsion in arbitrary dimensions  

SciTech Connect

In this paper, we reassess a particular R{sup 2}-type gravity action in D dimensions, recently studied by Nakasone and Oda, now taking torsion effects into account. Considering that the vielbein and the spin connection carry independent propagating degrees of freedom, we conclude that ghosts and tachyons are absent only if torsion is nonpropagating, and we also conclude that there is no room for massive gravitons. To include these excitations, we understand how to enlarge Nakasone-Oda's model by means of explicit torsion terms in the action and we discuss the unitarity of the enlarged model for arbitrary dimensions.

Hernaski, C. A.; Vargas-Paredes, A. A.; Helayeel-Neto, J. A. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, Urca, Rio de Janeiro, CEP 22290-180 (Brazil)

2009-12-15

298

Experimental investigation of cyclic thermomechanical deformation in torsion  

NASA Technical Reports Server (NTRS)

An investigation of thermomechanical testing and deformation behavior of tubular specimens under torsional loading is described. Experimental issues concerning test accuracy and control specific to thermomechanical loadings under a torsional regime are discussed. A series of shear strain-controlled tests involving the nickel-base superalloy Hastelloy X were performed with various temperature excursions and compared to similar thermomechanical uniaxial tests. The concept and use of second invariants of the deviatoric stress and strain tensors as a means of comparing uniaxial and torsional specimens is also briefly presented and discussed in light of previous thermomechanical tests conducted under uniaxial conditions.

Ellis, John R.; Castelli, Michael G.; Bakis, Charles E.

1992-01-01

299

Torsion of an epididymal cyst: a case report and review of the literature.  

PubMed

Torsion of an epididymal cyst (EC) on its pedicle is an extremely rare condition that resembles acute testicular torsion. Herein, a boy with EC torsion managed surgically is presented and discussed in light of the relevant literature. The presented child is probably the fourth case of pediatric EC torsion, and to our knowledge, the first report of a child who was known to have EC and was followed conservatively until the occurrence of EC torsion. PMID:24577990

Erikçi, Volkan; Ho?gör, Münevver; Y?ld?z, Melih; Aksoy, Nail; Okur, Özkan; Örnek, Y?lmazcan; Demircan, Yusuf

2013-01-01

300

Energy conditions in $f(T)$ gravity with non-minimal torsion-matter coupling  

E-print Network

The present paper examines the validity of energy bounds in a modified theory of gravity involving non-minimal coupling of torsion scalar and perfect fluid matter. In this respect, we formulate the general inequalities of energy conditions by assuming the flat FRW universe. For the application of these bounds, we particularly focus on two specific models that are recently proposed in literature and also choose the power law cosmology. We find the feasible constraints on the involved free parameters and evaluate their possible ranges graphically for the consistency of these energy bounds.

Zubair, M

2015-01-01

301

Angular correlations of galaxy distribution  

E-print Network

We study the angular correlations of various galaxy catalogs (CfA1, SSRS1, Perseus-Pisces, APM Bright Galaxies and Zwicky). We find that the angular correlation exponent is $\\gamma_a= 0.1 \\pm 0.1$ rather than $\\gamma_a=0.7$ as usually found by the standard correlation function $\\omega(\\theta)$. We identify the problem in the artificial decay of $\\omega(\\theta)$. Moreover we find that no characteristic angular scale is present in any of the analyzed catalogs. Finally we show that all the available data are consistent with each other and the angular distribution of galaxies is quite naturally compatible with a fractal structure with $D \\approx 2$.

M. Montuori; F. Sylos-Labini

1997-06-30

302

Ab InitioDetermination of the Roto-Torsional Energy Levels of trans-1,3Butadiene  

Microsoft Academic Search

In this paper, the flexible model based on relaxedab initiocalculations, which has been several times employed for vibrational calculations, is extended to the analysis of the rotational structures starting by the roto-torsional bands oftrans-1,3-butadiene. For this purpose, the potential energy surface and the kinetic energy parameters of the ?13vibrational mode of butadiene are obtained with the Möller–Plesset perturbation theory up

M. L Senent

1998-01-01

303

Patterns of dissociate torsional-vertical nystagmus in internuclear ophthalmoplegia.  

PubMed

To explore the patterns and mechanisms of jerky seesaw nystagmus in internuclear ophthalmoplegia (INO), we analyzed the nystagmus patterns in 33 patients with dissociated torsional-vertical nystagmus and INO. In 11 (33%) patients, the nystagmus was ipsiversive torsional in both eyes with vertical components in the opposite directions. In contrast, 18 (55%) patients showed ipsiversive torsional nystagmus with a larger upbeat component in the contralesional eye. Four (12%) patients exhibited ipsiversive torsional nystagmus with a greater downbeat component in the ipsilesional eye. At least one component of contraversive ocular tilt reaction was associated in most patients (30/33, 91%). The patterns of jerky seesaw nystagmus in INO suggest a disruption of neural pathways from the contralateral vertical semicircular canals with or without concomitant damage to the fibers from the contralateral utricle in or near the medial longitudinal fasciculus. PMID:21951004

Jeong, Seong-Hae; Kim, Eung Kyu; Lee, Jun; Choi, Kwang-Dong; Kim, Ji Soo

2011-09-01

304

Lung torsion after tracheoesophageal fistula repair in an infant  

PubMed Central

Lung torsion is a very rare event that has been reported in only 9 cases in the pediatric literature but has not yet been reported in Korean infants. We present a case of lung torsion after tracheoesophageal fistula repair in an infant. Bloody secretion from the endotracheal tube and chest radiographs and computed tomographic scan results indicated lung torsion. Emergency exploration indicated 180° torsion of the right upper lobe (RUL) and right middle lobe (RML). After detorsion of both lobes, some improvement in the RUL color was observed, but the color change in the RML could not be determined. Although viability of the RML could not be proven, pexy was performed for both the lobes. Despite reoperation, clinical signs and symptoms did not improve. The bronchoscopy revealed a patent airway in the RUL but not in the RML. Finally, the RML was surgically removed. The patient was discharged on the 42nd day after birth. PMID:23646058

Yang, Eun Mi; Song, Eun Song; in Jang, Hae; Jeong, In Seok

2013-01-01

305

Torsion of the leg determined by computed tomography.  

PubMed

Torsion of the leg was measured in 50 adults by computed tomography. The tangent to the dorsal aspect of the femoral condyles gave the proximal reference line. The distal reference line joined the centers of the medial and lateral malleoli. Tibial torsion was measured as the inclination between the dorsal tangent to the tibial condyles and the distal reference line, and torsion of the leg was measured as the inclination between the proximal and the distal reference lines. The anatomy of the dorsal aspects of the tibial condyles was more inconsistent than the anatomy of the dorsal aspects of the femoral condyles. In the females the external torsion of the leg was 38 +/- 9 degrees on the right side and 37 +/- 11 degrees on the left side. In the males the values were 41 +/- 6 degrees and 40 +/- 10 degrees, respectively. PMID:2750510

Reikerås, O; Høiseth, A

1989-06-01

306

Torsion effect on fully developed flow in a helical pipe  

NASA Technical Reports Server (NTRS)

Two techniques, a series expansion method of perturbed Poiseuille flow valid for low Dean numbers and a solution of the complete Navier-Stokes equation applicable to intermediate Dean values, are used to investigate the torsion effect on the fully developed laminar flow in a helical pipe of constant circular cross section. For the secondary flow patterns, the results show that the presence of torsion can produce a significant effect if the ratio of the curvature to the torsion is of order unity. The secondary flow is distorted in these cases. It is noted that the torsion effect is, however, usually small, and that the secondary flow has the usual pattern of a pair of counter-rotating vortices of nearly equal strength.

Kao, Hsiao C.

1987-01-01

307

Cosmic Magnetic Fields from Torsion Modes and Massive Photon Inflation  

NASA Astrophysics Data System (ADS)

Earlier Barrow & Tsagas (2008) showed that a slower decay of magnetic fields are present in open Friedmann universes, with traditional Maxwell equations. In their paper magnetic fields of the order of B˜10–33 G which are far below the value required to seed galactic dynamos were obtained. In this paper galactic dynamo seeds of the order of B˜10–23 G are obtained from massive electrodynamics in Einstein–Cartan–Proca (ECP) expanding universe of de Sitter type. Slow decay of magnetic fields in photon-torsion coupling in QED (Garcia de Andrade 2011b) have been recently shown by Garcia de Andrade (2012) also not be able to seed galactic dynamos. Torsion modes are constrained by the field equations. Space-time torsion is shown to be explicitly responsible for the slow decay of cosmic magnetic field. In the absence of massive photon torsion coupling the magnetic field decay is of the order B˜t–3/2, while when torsion is turn on B˜t–1.2. The pure massive-photon-torsion contribution amplifies the magnetic field by Btorsion˜t0.1 which characterizes an extremely slow magnetic dynamo action due to purely torsion gravitational effects. Recently, Barrow et al. (2012) have obtained superadiabatic amplification of B-fields in the Friedmann open cosmology which lies within 10–20 G and 10–12 G which falls very comfortable within limits to seed galactic dynamos. Other simple solutions where B-field decays as B˜a–1, relatively weak photon-torsion coupling approximation. These solutions are obtained for the de Sitter and Friedmann metrics.

Garcia de Andrade, L. C.

2014-09-01

308

A new method for measuring torsional deformity in scoliosis  

Microsoft Academic Search

Background  The importance of spinal rotational and torsional deformity in the etiology and the management of scoliosis are well-recognized.\\u000a For measuring the posterior spinal component rotation, Ho's method was reported to be reliable. However, there is no practical\\u000a method to measure the anterior spinal component rotation. Moreover, there is also no method to quantify the spinal torsional\\u000a deformity in scoliosis. The

Toshio Doi; Satoshi Kido; Umito Kuwashima; Osamu Tono; Kiyoshi Tarukado; Katsumi Harimaya; Yoshihiro Matsumoto; Kenichi Kawaguchi; Yukihide Iwamoto

2011-01-01

309

Salvage Splenopexy for Torsion of Wandering Spleen in a Child  

PubMed Central

The wandering spleen is a rare condition characterized by the absence or underdevelopment of one or all of the splenic suspensory ligaments that resulting in increased splenic mobility and rarely torsion. Preventing infarction is the aim of a prompt surgery by splenopexy. We report a case of salvage splenopexy in torsion of a wandering spleen in a three year old girl presented with severe abdominal pain for three days. PMID:24834385

Goyal, Ram Babu; Prabhakar, Girish; Mathur, Praveen; Mala, Tariq Ahmed

2014-01-01

310

A nationwide epidemiological study of testicular torsion in Korea.  

PubMed

Testicular torsion is a surgical emergency in the field of urology. Knowledge of the epidemiology and pathophysiology is significant to an urologist. However, the epidemiology of testicular torsion in Korea has not been studied. We performed a nationwide epidemiological study to improve knowledge of the epidemiology of testicular torsion. From 2006-2011, the Korean Urologic Association began the patient registry service. The annual number of patients with testicular torsion from 2006 to 2011 were 225, 250, 271, 277, 345, and 210, respectively. The overall incidence of testicular torsion in males was 1.1 per 100,000; However, the incidence in men less than 25 yr old was 2.9 per 100,000. Adolescents showed the highest incidence. Total testicular salvage rate was 75.7% in this survey. There was no geographic difference of testicular salvage rate. Minimizing the possibility of orchiectomy for testicular torsion is important to improve public awareness to expedite presentation and provider education to improve diagnosis and surgery. PMID:25469070

Lee, Sol Min; Huh, Jung-Sik; Baek, Minki; Yoo, Koo Han; Min, Gyeong Eun; Lee, Hyung-Lae; Lee, Dong-Gi

2014-12-01

311

Coherent Control of Molecular Torsion and the Active-space Decomposition Method  

NASA Astrophysics Data System (ADS)

This dissertation discusses schemes and applications for the strong-field control of molecular torsions as well as introduces the active-space decomposition method. In the first part, a route to realize general control over the torsional motions of a class of biaryl compounds is proposed. Torsion in biaryl compounds--molecules with two aromatic moieties connected by a bond about which the barrier to rotation is small--mediates the electronic coupling between the two rings in the molecule. Thus, by controlling the torsion angle, one also controls the electron transfer and transport rates, the absorption and emission spectra, and the molecule's chirality. In our scheme, a non-resonant half-cycle pulse interacts with the permanent dipole of only one moiety of the pre-oriented biaryl compound. In the non-adiabatic regime, coherent motion is initiated by the half-cycle pulse. In the adiabatic regime, the torsion angle is tuned by the pulse. By properly choosing the parameters and polarization of the half-cycle pulse, we show that free internal rotation can be started or that the molecular chirality can be inverted. Then, with the aid of optimal control theory, we design "deracemizing" control pulses, i.e., control pulses that convert a racemic mixture into an enantiopure mixture. Finally, we explore the potential for this type of control in a single-molecule pulling experiment. In the second part, we describe the active space decomposition method for computing excited states of molecular dimers. In this method, the dimer's wavefunction is expressed as a linear combination of direct products of orthogonal localized monomer states. The adiabatic dimer states are found by diagonalizing the Hamiltonian in this direct product space. Matrix elements between direct product states are computed directly, without ever explicitly forming the dimer wavefunction, thus enabling calculations of dimers with active space sizes that would be otherwise impossible. The decomposed wavefunctions approach the exact dimer wavefunctions in two limiting cases: when there is no coupling between the two monomers and when a full set of monomer states is used. After introducing the method, we apply it to the computation of model Hamiltonians for the singlet fission process.

Parker, Shane Matthew

312

Flap-lag-torsion aeroelastic stability of a circulation control rotor in forward flight  

NASA Technical Reports Server (NTRS)

The aeroelastic stability of a circulation control rotor blade undergoing three degrees of motion (flap, lag, and torsion) is investigated in forward flight. Quasi-steady strip theory is used to evaluate the aerodynamics forces; and the airfoil characteristics are from data tables. The propulsive and the auxiliary power trims are calculated from vehicle and rotor equilibrium equations through the numerical integration of element forces in azimuth as well as in radial directions. The nonlinear time dependent periodic blade response is calculated using an iterative procedure based on Floquet theory. The periodic perturbation equations are solved for stability using Floquet transition matrix theory. The effects of several parameters on blade stability are examined, including advance ratio, collective pitch, thrust level, shaft tilt, structural stiffnesses variation, and propulsive and auxiliary power trims.

Chopra, Inderjit; Hong, Chang-Ho

1987-01-01

313

Calculating the nuclear mass at finite angular momenta  

E-print Network

Mean field methods to calculate the nuclear mass are extended into the high spin regime to calculate the nuclear binding energy as a function of proton number, neutron number and angular momentum. Comparing the trend as a function of mass number for a selection of high-spin states, a similar agreement between theory and experiment is obtained as for ground state masses.

B. G. Carlsson; I. Ragnarsson

2005-03-30

314

Control of Torsional Vibrations by Pendulum Masses  

NASA Technical Reports Server (NTRS)

Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations. Unexplained, so far, remains the problem of behavior of pendulum masses in other critical zones to which they are not tuned, their dynamic behavior at some tuning other than in resonance, and their effect within a compound vibration system and at simultaneous application of several differently tuned pendulous masses. These problems are analyzed in the present report. The results constitute an enlargement of the scope of application of pendulum masses, especially for in-line engines. Among other things it is found that the natural frequency of a system can be raised by means of a correspondingly tuned pendulum mass. The formulas necessary for the design of any practical version are developed, and a pendulum mass having two different natural frequencies simultaneously is described.

Stieglitz, Albert

1942-01-01

315

Testicular torsion on the Jos Plateau.  

PubMed

In order to determine the pattern and the factors that influenced outcome, we retrospectively studied fifty-seven patients with torsion of the testis admitted to the Jos University Teaching hospital between August 1993 and July 2001. The age ranged from 2 to 55 years with a mean of 22.7 years. Majority (79%) of the patients were in the second and third decades of life. The main suspected precipitating factors in this study were cold weather and scrotal trauma: in 28% of the cases no cause could be ascertained. Eight (14%) patients presented within 4 hours and 35 (61%) presented after 24 hours of the onset of symptoms. Both sides were equally affected. Testicular pain, retraction and scrotal swelling were the most common presenting complaints. The highest incidence 65%) occurred between November and February when the weather on the Jos plateau is coldest. At surgery, 34 (60%) patients were found to have associated congenital anomalies; in 22 (39%) patients, the testis was non-viable. There was no mortality in this series and the complications were superficial wound infection (14%), testicular atrophy (7%) and sub-fertility (16%). High index of suspicion in a patient with acute scrotum, prompt and effective surgery will improve testicular salvage. PMID:14529218

Ugwu, B T; Dakum, N K; Yiltok, S J; Mbah, N; Legbo, J N; Uba, A F; Orkar, K S; Ramyil, V M

2003-06-01

316

Composite model for DNA torsion dynamics.  

PubMed

DNA torsion dynamics is essential in the transcription process; a simple model for it, in reasonable agreement with experimental observations, has been proposed by Yakushevich (Y) and developed by several authors; in this, the nucleotides (the DNA subunits made of a sugar-phosphate group and the attached nitrogen base) are described by a single degree of freedom. In this paper we propose and investigate, both analytically and numerically, a "composite" version of the Y model, in which the sugar-phosphate group and the base are described by separate degrees of freedom. The model proposed here contains as a particular case the Y model and shares with it many features and results, but represents an improvement from both the conceptual and the phenomenological point of view. It provides a more realistic description of DNA and possibly a justification for the use of models which consider the DNA chain as uniform. It shows that the existence of solitons is a generic feature of the underlying nonlinear dynamics and is to a large extent independent of the detailed modeling of DNA. The model we consider supports solitonic solutions, qualitatively and quantitatively very similar to the Y solitons, in a fully realistic range of all the physical parameters characterizing the DNA. PMID:17358379

Cadoni, Mariano; De Leo, Roberto; Gaeta, Giuseppe

2007-02-01

317

Torsional vibration reduction using passive nonlinear absorbers  

NASA Astrophysics Data System (ADS)

This paper considers the dynamic performance of systems of centrifugal pendulum vibration absorbers that are used to attenuate torsional vibrations in rotating systems. These absorbers, which can be found in certain IC engines and helicopter rotors, consist of movable masses whose centers of mass are kinematically restricted to move along prescribed paths relative to the rotor of interest. The most common choice for absorber paths are simple circles that are slightly mistuned from the desired order, so that undesirable nonlinear behaviors are avoided when the absorbers undergo large amplitude motions. In this work we consider a range of different path types and tunings, with the goal of optimizing performance over a wide operating range. This analytical study relies on a mathematical model of a rotor fitted with N identical, general-path absorbers, and utilizes perturbation techniques to obtain analytical estimates for the response of the rotor and the absorbers. The results are used to select path parameters based on selected performance measures, and the results are verified via simulation studies. It is shown that slightly overtuned cycloidal paths provide excellent vibration reduction characteristics and prevent the occurrence of nonlinear instabilities and vibration localization in the response of the absorbers.

Shaw, Steven W.; Alsuwaiyan, Abdallah

2000-04-01

318

Relationship of the commutation rules to classical-like representations of quantum angular momenta addition  

E-print Network

­Gordan coefficients. This set shows that the angle can be a well-defined variable in quantum mechanics. An empirical , followed by quantum mechanical considerations, leads to the vanishing of certain quantum angular momentum to introduce the quantum theory of angular momentum as early as possible instead of the vector model

California at Santa Cruz, University of

319

Variations in atmospheric angular momentum  

NASA Technical Reports Server (NTRS)

Twice-daily values of the atmosphere's angular momentum about the polar axis during the five years from 1976 through 1980 are presented in graphs and a table. The compilation is based on a global data set, incorporating 90 percent of the mass of the atmosphere. The relationship between changes in the angular momentum of the atmosphere and changes in the length of day is described, as are the main sources of error in the data. The variability in angular momentum is revealed in a preliminary fashion by means of a spectral decomposition. The data presented should stimulate comparisons with other measures of the length of day and so provide a basis for greater understanding of Earth-atmosphere interactions.

Rosen, R. D.; Salstein, D. A.

1981-01-01

320

Angular control of optical cavities in a radiation-pressure-dominated regime: the Enhanced LIGO case.  

PubMed

We describe the angular sensing and control (ASC) of 4 km detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO). Enhanced LIGO, the culmination of the first generation LIGO detectors, operated between 2009 and 2010 with about 40 kW of laser power in the arm cavities. In this regime, radiation-pressure effects are significant and induce instabilities in the angular opto-mechanical transfer functions. Here we present and motivate the ASC design in this extreme case and present the results of its implementation in Enhanced LIGO. Highlights of the ASC performance are successful control of opto-mechanical torsional modes, relative mirror motions of ? 1×10(-7) rad rms, and limited impact on in-band strain sensitivity. PMID:24323024

Dooley, Katherine L; Barsotti, Lisa; Adhikari, Rana X; Evans, Matthew; Fricke, Tobin T; Fritschel, Peter; Frolov, Valera; Kawabe, Keita; Smith-Lefebvre, Nicolás

2013-12-01

321

Towards an invariant geometry of double field theory  

E-print Network

We introduce a geometrical framework for double field theory in which generalized Riemann and torsion tensors are defined without reference to a particular basis. This invariant geometry provides a unifying framework for ...

Hohm, Olaf

322

Investigation of the torsional barrier of EDOT using molecular mechanics and DFT methods.  

PubMed

When heterocyclic monomers are polymerized by electrochemical or chemical methods, they form fully conjugated polymers which have a wide range of applications due to their outstanding electronic properties. Among this class of compounds, thiophene derivatives are widely used due to their chemical stability and synthesis flexibility. With the goal to investigate the torsion barrier of polymer chains, a few units of 3,4-ethylenedioxythiophene (EDOT) were chosen and submitted to molecular mechanics (MM), density functional theory (DFT) and coupled cluster CCSD(T) calculations. This study helps to understand the performance and transferability of force fields used in molecular mechanics and molecular dynamics simulations often used to describe structure-property relationships of those systems. Determination of inter-ring torsion angle was performed in a comparative study using both force field, DFT and CCSD(T) methods. A good agreement was noticed between MM and QC results and highlights the importance of the description of the interactions involving the oxygen atoms present in the structure of EDOT. These observations are related to the ?,?-coupling that occurs between the monomer units and yields a linear polymer. DFT HOMO and LUMO orbitals were also presented. Finally, UV-vis spectra of EDOT units were obtained using several levels of theory by means of time-dependent DFT calculations (TD-DFT). PMID:25116151

Durães, Jussara A; da Silva Filho, Demétrio A; Ceschin, Artemis M; Sales, Maria J A; Martins, João B L

2014-08-01

323

Does a randall-sundrum scenario create the illusion of a torsion-free universe?  

PubMed

We consider spacetime with torsion in a Randall-Sundrum scenario where torsion, identified with the rank-2 Kalb-Ramond field, exists in the bulk together with gravity. While the interactions of both graviton and torsion in the bulk are controlled by the Planck mass, an additional exponential suppression comes for the torsion zero-mode on the visible brane. This may serve as a natural explanation of why the effect of torsion is so much weaker than that of curvature on the brane. The massive torsion modes, on the other hand, are correlated with the corresponding gravitonic modes and may be detectable in TeV-scale experiments. PMID:12225074

Mukhopadhyaya, Biswarup; Sen, Somasri; SenGupta, Soumitra

2002-09-16

324

DNA torsion as a feedback mediator of transcription and chromatin dynamics.  

PubMed

The double helical structure of DNA lends itself to topological constraints. Many DNA-based processes alter the topological state of DNA, generating torsional stress, which is efficiently relieved by topoisomerases. Maintaining this topological balance is crucial to cell survival, as excessive torsional strain risks DNA damage. Here, we review the mechanisms that generate and modulate DNA torsion within the cell. In particular, we discuss how transcription-generated torsional stress affects Pol II kinetics and chromatin dynamics, highlighting an emerging role of DNA torsion as a feedback mediator of torsion-generating processes. PMID:24819949

Teves, Sheila S; Henikoff, Steven

2014-01-01

325

Angular momentum in QGP holography  

NASA Astrophysics Data System (ADS)

The quark chemical potential is one of the fundamental parameters describing the quark-gluon plasma produced by sufficiently energetic heavy-ion collisions. It is not large at the extremely high temperatures probed by the LHC, but it plays a key role in discussions of the beam energy scan programmes at the RHIC and other facilities. On the other hand, collisions at such energies typically (that is, in peripheral collisions) give rise to very high values of the angular momentum density. Here we explain that holographic estimates of the quark chemical potential of a rotating sample of plasma can be very considerably improved by taking the angular momentum into account.

McInnes, Brett

2014-10-01

326

Angular output of hollow, metal-lined, waveguide Raman sensors  

SciTech Connect

Hollow, metal-lined waveguides used as gas sensors based on spontaneous Raman scattering are capable of large angular collection. The collection of light from a large solid angle implies the collection of a large number of waveguide modes. An accurate estimation of the propagation losses for these modes is required to predict the total collected Raman power. We report a theory/experimental comparison of the Raman power collected as a function of the solid angle and waveguide length. New theoretical observations are compared with previous theory appropriate only for low-order modes. A cutback experiment is demonstrated to verify the validity of either theory. The angular distribution of Raman light is measured using aluminum and silver-lined waveguides of varying lengths.

Biedrzycki, Stephen; Buric, Michael P.; Falk, Joel; Woodruff, Steven D.

2012-04-20

327

Flutter Suppression of Composite Plate Wings Based on the Measurement and Control of Torsional Vibration Mode (The Second Report)  

NASA Astrophysics Data System (ADS)

The present paper treats the flutter suppression of composite plate wings with segmented piezoelectric sensors and actuators. In the second report of this paper, validity of the flutter suppression based on the optimal placement of sensors and actuators is examined for composite plate wings. Modal sensor for measurement of the modal displacement of the first torsional vibration mode is designed by the optimal placement of PVDF sensors based on the minimization criterion of observation spillover. Actuation system to generate the modal force for the first torsional vibration mode is designed by the optimal placement of PZT actuators based on the minimization criterion of control spillover. Aeroelastic analysis of composite plates is based on the finite element method and the subsonic unsteady lifting surface theory. The minimum state method is applied to approximate the unsteady aerodynamic forces as the transfer functions of the Laplace variables. The effectiveness of optimal placement of sensors and actuators in the flutter suppression is clarified through the numerical examples.

Kameyama, Masaki

328

Analysis of line broadening and spectral asymmetry in an all-fiber torsional acousto-optic band-pass filter  

NASA Astrophysics Data System (ADS)

The transmission properties of an all-fiber torsional acousto-optic (AO) band-pass filter with a sub-nm bandwidth is studied. The device is based on torsional AO coupling in a highly birefringent (HB) optical fiber. The full width at half maximum (FWHM) measured in a conventional band (C-band) is 0.88 nm, which is compared with the theoretical value of 0.45 nm estimated by using the coupled mode theory. The line broadening and the spectral asymmetry observed in experiments are investigated in detail through our theoretical model and full numerical analyses. The influence of the non-uniformity in the birefringence of the HB fiber on the filter's transmission is analyzed quantitatively in terms of the change in the filtering bandwidth, the sidelobe asymmetry, and the resonance shift.

Kim, Ilhwan; Lee, Kwang Jo; Hwang, In-Kag

2014-12-01

329

Early onset torsion dystonia (Oppenheim's dystonia)  

PubMed Central

Early onset torsion dystonia (EOTD) is a rare movement disorder characterized by involuntary, repetitive, sustained muscle contractions or postures involving one or more sites of the body. A US study estimated the prevalence at approximately 1 in 30,000. The estimated prevalence in the general population of Europe seems to be lower, ranging from 1 in 330,000 to 1 in 200,000, although precise numbers are currently not available. The estimated prevalence in the Ashkenazi Jewish population is approximately five to ten times higher, due to a founder mutation. Symptoms of EOTD typically develop first in an arm or leg in middle to late childhood and progress in approximately 30% of patients to other body regions (generalized dystonia) within about five years. Distribution and severity of symptoms vary widely between affected individuals. The majority of cases from various ethnic groups are caused by an autosomal dominantly inherited deletion of 3 bp (GAG) in the DYT1 gene on chromosome 9q34. This gene encodes a protein named torsinA, which is presumed to act as a chaperone protein associated with the endoplasmic reticulum and the nuclear envelope. It may interact with the dopamine transporter and participate in intracellular trafficking, although its precise function within the cell remains to be determined. Molecular genetic diagnostic and genetic counseling is recommended for individuals with age of onset below 26 years, and may also be considered in those with onset after 26 years having a relative with typical early onset dystonia. Treatment options include botulinum toxin injections for focal symptoms, pharmacological therapy such as anticholinergics (most commonly trihexiphenydil) for generalized dystonia and surgical approaches such as deep brain stimulation of the internal globus pallidus or intrathecal baclofen application in severe cases. All patients have normal cognitive function, and despite a high rate of generalization of dystonia, 75% of those patients are able to maintain ambulation and independence, and therefore a comparatively good quality of life, with modern treatment modalities. PMID:17129379

Kamm, Christoph

2006-01-01

330

Numerical modeling of pendulum dampers in torsional systems  

SciTech Connect

Centrifugal pendulum-design dampers are utilized in torsional systems to reduce the vibration amplitude at certain objectionable torsional speeds. The damper is tuned by proper design of its mass, dimensions, and position on a carrier disk, which is rigidly attached to the torsional system. The effects of the pendulum damper on the response of the torsional system may be included by modifying the structural model to include a separate damper element representing each order of the pendulum damper. The stiffness and mass matrices for a damper element are dependent upon the order of vibration being dampened, the mass, and the geometry of the damper. A general form of the mass and stiffness equations for a simple centrifugal pendulum damper are derived from first principles using Lagrange's equations of motion. The analysis of torsional systems with pendulum dampers utilizing the mass and stiffness properties developed is included in the program SHAMS. SHAMS calculates the steady-state response of a system of springs and masses to harmonic loads using modal superposition. The response of a crankshaft system with and without the pendulum dampers are included as a case study.

Johnston, P.R.; Shusto, L.M.

1986-01-01

331

Two-component spinors in spacetimes with torsionful affinities  

NASA Astrophysics Data System (ADS)

The essentially unique torsionful version of the classical two-component spinor formalisms of Infeld and van der Waerden is presented. All the metric spinors and connecting objects that arise here are formally the same as the ones borne by the traditional formalisms. Any spin-affine connexion appears to possess a torsional part which is conveniently chosen as a suitable asymmetric contribution. Such a torsional affine contribution thus supplies a gauge-invariant potential that can eventually be taken to carry an observable character, and thereby effectively takes over the role of any trivially realizable symmetric contribution. The overall curvature spinors for any spin-affine connexion accordingly emerge from the irreducible decomposition of a mixed world-spin object which in turn comes out of the action on elementary spinors of a typical torsionful second-order covariant derivative operator. Explicit curvature expansions are likewise exhibited which fill in the gap related to their absence from the literature. It is then pointed out that the utilization of the torsionful spinor framework may afford locally some new physical descriptions.

Cardoso, J. G.

2015-01-01

332

Elevated temperature axial and torsional fatigue behavior of Haynes 188  

NASA Technical Reports Server (NTRS)

The results are reported for high-temperature axial and torsional low-cycle fatigue experiments performed at 760 C in air on thin-walled tubular specimens of Haynes 188, a wrought cobalt-based superalloy. Data are also presented for mean coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. This data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME Boiler and Pressure Code), Manson-Halford, modified multiaxiality factor (proposed in this paper), modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The modified multiaxiality factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

Bonacuse, Peter J.; Kalluri, Sreeramesh

1995-01-01

333

Elevated temperature axial and torsional fatigue behavior of Haynes 188  

NASA Technical Reports Server (NTRS)

The results of high-temperature axial and torsional low-cycle fatigue experiments performed on Haynes 188, a wrought cobalt-base superalloy, are reported. Fatigue tests were performed at 760 C in air on thin-walled tubular specimens at various ranges under strain control. Data are also presented for coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. The data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME boiler and pressure vessel code), Manson-Halford, Modified Multiaxiality Factor (proposed here), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

Bonacuse, Peter J.; Kalluri, Sreeramesh

1992-01-01

334

Direct torsional actuation of microcantilevers using magnetic excitation  

NASA Astrophysics Data System (ADS)

Torsional mode dynamic force microscopy can be used for a wide range of studies including mapping lateral contact stiffness, torsional frequency or amplitude modulation imaging, and dynamic friction measurements of various materials. Piezo-actuation of the cantilever is commonly used, but it introduces spurious resonances, limiting the frequency range that can be sampled, and rendering the technique particularly difficult to apply in liquid medium where the cantilever oscillations are significantly damped. Here, we demonstrate a method that enables direct torsional actuation of cantilevers with high uniformity over wide frequency ranges by attaching a micrometer-scale magnetic bead on the back side of the cantilever. We show that when beads are magnetized along the width of the cantilever, efficient torsional actuation of the cantilevers can be achieved using a magnetic field produced from a solenoid placed underneath the sample. We demonstrate the capability of this technique by imaging atomic steps on graphite surfaces in tapping mode near the first torsional resonance of the cantilever in dodecane. The technique is also applied to map the variations in the lateral contact stiffness on the surface of graphite and polydiacetylene monolayers.

Gosvami, Nitya Nand; Nalam, Prathima C.; Exarhos, Annemarie L.; Tam, Qizhan; Kikkawa, James M.; Carpick, Robert W.

2014-09-01

335

Torsion of the Retroperitoneal Kidney: Uncommon or Underreported?  

PubMed Central

Vascular torsion in a renal allograft after placement in the retroperitoneum is rare and has only been reported twice in the literature. It is an extrinsically mediated process that occurs at the vascular pedicle resulting in graft compromise and potential loss. Rapid diagnosis and immediate surgical intervention may salvage allograft function. Herein, we present a unique case of a 42-year-old male that developed renal allograft torsion following a second kidney transplant placed in the retroperitoneum. Immediate detorsion did not resolve allograft dysfunction, and a biopsy revealed acute cellular mediated rejection. After antithymocyte globulin treatment, allograft function was salvaged. A review of the current literature shows that the incidence, morbidity, and long term allograft function of intraperitoneal and extraperitoneal torsion are different. As such, torsion of the retroperitoneal kidney demonstrates encouraging allograft salvage rates. Only the third case reported to date, this serves as a contribution to the growing body of literature in retroperitoneal renal torsion and reviews the risks, medication considerations, diagnostic tests, and treatment modalities in a unique disease process. PMID:24551473

Sosin, Michael; Lumeh, Wuya; Cooper, Matthew

2014-01-01

336

Prune belly syndrome, splenic torsion, and malrotation: a case report.  

PubMed

An 18 year old male with a history of prune belly syndrome (PBS) presented with acute abdominal pain and palpable left upper quadrant mass. Computed tomography (CT) of the abdomen revealed a medialized spleen with a "whirl sign" in the splenic vessels, consistent with splenic torsion. Coincidentally, the small bowel was also noted to be on the right side of the abdomen, while the colon was located on the left, indicative of malrotation. Emergent diagnostic laparoscopy confirmed splenic torsion and intestinal malrotation. Successful laparoscopic reduction of the splenic torsion was achieved, however, conversion to an open procedure by a vertical midline incision was necessary owing to the patient's unique anatomy. Open splenopexy with a mesh sling and Ladd's procedure were subsequently performed. Malrotation and wandering spleen are known, rare associated anomalies in PBS; however, both have not been reported concurrently in a patient with PBS in the literature. In patients with PBS, acute abdominal pain, and an abdominal mass, high clinical suspicion for gastrointestinal malformations and prompt attention can result in spleen preservation and appropriate malrotation management. We present a case of a teenager who presented with a history of PBS, acute abdominal pain, and a palpable abdominal mass. The patient was found to have splenic torsion and intestinal malrotation. The clinical findings, diagnostic imaging, and surgical treatment options of splenic torsion are reviewed. PMID:23414901

Tran, Sifrance; Grossman, Eric; Barsness, Katherine A

2013-02-01

337

Ab initio determination of mode coupling in HSSH - The torsional splitting in the first excited S-S stretching state  

NASA Technical Reports Server (NTRS)

A mechanism for the enhanced splitting detected in the millimeter-wave rotational spectra of the first excited S-S stretching state of HSSH (disulfane) has been studied. The mechanism, which involves a potential coupling between the first excited S-S stretching state and excited torsional states, has been investigated in part by the use of ab initio theory. Based on an ab initio potential surface, coupling matrix elements have been calculated, and the amount of splitting has then been estimated by second-order perturbation theory. The result, while not in quantitative agreement with the measured splitting, lends plausibility to the assumed mechanism.

Herbst, Eric; Winnewisser, G.; Yamada, K. M. T.; Defrees, D. J.; Mclean, A. D.

1989-01-01

338

Heat transport as torsional responses and Keldysh formalism in a curved spacetime  

NASA Astrophysics Data System (ADS)

We revisit a theory of heat transport in the light of a gauge theory of gravity and find the proper heat current with a corresponding gauge field, which yields the natural definitions of the heat magnetization and the Kubo-formula contribution to the thermal conductivity as torsional responses. We also develop a general framework for calculating gravitational responses by combining the Keldysh and Cartan formalisms. By using this framework, we explicitly calculate these two quantities and reproduce the Wiedemann-Franz law for the thermal Hall conductivity in the clean and non-interacting case. Finally, we discuss an effective action for the quantized thermal Hall effect in (2 +1)-D topological superconductors.

Shitade, Atsuo

2014-12-01

339

Angular Diameters of O- and B-type Stars  

NASA Astrophysics Data System (ADS)

We are observing a sample of 10 O-type stars and 60 B-type stars to determine angular diameters using the Center for High Angular Resolution Astronomy (CHARA) Array, the foremost optical long baseline interferometer in the world. Our goal is to establish accurate stellar parameters to test modern theories of stellar evolution that include rotation. We will combine our stellar angular diameter measurements with flux and line measurements from spectroscopy, projected rotational velocities, and distances to determine radius, effective temperature, luminosity, equatorial rotational velocity, and evolutionary mass. Knowing these properties will allow us to place the stars in a Hertzsprung-Russell diagram and obtain estimates for the age and evolutionary state.

Gordon, Kathryn; Gies, Douglas; Schaefer, Gail

2015-01-01

340

Sage basics Problem: Triangulations Problem: Torsion in homology Advertisements, links Algebraic topology in Sage  

E-print Network

Sage basics Problem: Triangulations Problem: Torsion in homology Advertisements, links Algebraic topology in Sage John H. Palmieri Department of Mathematics University of Washington Cascade Topology Seminar December 1, 2012 Eugene #12;Sage basics Problem: Triangulations Problem: Torsion in homology

Palmieri, John

341

Increased external tibial torsion in Osgood-Schlatter disease.  

PubMed

We studied the relationship between Osgood-Schlatter disease and torsional abnormalities of the lower limb in 21 boys with this condition and 20 age- and sex-matched controls. 3 groups of knees (20 control knees, 21 symptomatic and 21 asymptomatic or less symptomatic knees) were subjected to clinical, radiographic and CT evaluation. We found no statistically significant differences between patients and controls, as regards femoral anteversion, patellar congruence angle, patellar tilt angle and anterior tibial tuberosity-trochlear groove distance, but the condylomalleolar angle and tibial torsion angle were greater in patients. We found no differences between symptomatic and asymptomatic or less symptomatic knees in any of the parameters. All the symptomatic knees were on the side preferentially involved in jumping and sprinting. This increase in external tibial torsion may play a role as a predisposing mechanical factor in the onset of Osgood-Schlatter disease in male athletes. PMID:14521294

Gigante, Antonio; Bevilacqua, Claudia; Bonetti, Massimo G; Greco, Francesco

2003-08-01

342

[Torsion of the testicle and testicular adnexa in children].  

PubMed

Between 1987-May 1994 the treatment results of 73 boys with the symptoms of "acute scrotum" were presented. 67 boys were operated. During the operations in 14 cases the torsion of testicle were observed, in 2 cases necrotically changed testicles were removed. Among 53 boys torsion of the appendices of the testis were observed, the appendices were removed. 6 boys with the diagnosis of torsion the appendices of the testis were conservatively treated with a good result. On the basis of literature review and own experiences the children should be qualified for operation by the anamnesis and physical examination independently from additional and sonography results. The acute symptoms of scrotum or inguinal canal in the absence of the testicle in scrotum should indicate at the need for early surgical intervention in case of acute symptoms concerning testicles and scrotum. The epididimitis and orchitis is rare with children before pubescence. One child with the epididimitis abscess, the epididimis was removed. PMID:8999695

Ta?ski, Z; Pogodski, E; Gacki, T; Jarzabek, Z

1994-01-01

343

Complete axial torsion of pregnant uterus with leiomyoma.  

PubMed

Uterine torsion is defined as a rotation of the uterus of more than 45° along its long axis. It is a rare complication during pregnancy; a common cause of torsion can be uterine myoma. Here we describe the case of a 27-year-old G2P1+0 woman at 15?weeks 3?day pregnancy, who presented to our outpatient department as a case of acute abdomen, in a state of shock. Clinical findings did not correlate with investigation. On lapratomy she was diagnosed as a case of complete axial torsion of pregnant uterus with fundal myoma with massive abruption. Early diagnosis and timely intervention would help in improving both maternal and fetal outcome. PMID:25193815

Sachan, Rekha; Patel, M L; Sachan, Pushpalata; Arora, Anubha

2014-01-01

344

Torsion Strain Effects on Critical Currents of Hts Superconducting Tapes  

NASA Astrophysics Data System (ADS)

A torsional twist strain effect on the critical current of a thin HTS tape has been found to be well described by a longitudinal strain model taking into account the internal shortening compressive strains accompanied with the tensile longitudinal strains due to a torsional twist. The critical current of a twisted tape is given by the integration of the critical current densities corresponding to the strain distribution over the tape cross-section using axial strain data of the tape. The model is supported with experimental results of YBCO and BSCCO-2223 tapes. It has been also found that torsional twisting effects on the critical currents of a tape composing of the conventional lapped-tape cable and the twisted stacked-tape cable are described by the same equation as that of a twisted single tape.

Takayasu, Makoto; Minervini, Joseph V.; Bromberg, Leslie

2010-04-01

345

Torsional Stick-Slip Behavior in WS2 Nanotubes  

NASA Astrophysics Data System (ADS)

We experimentally observed atomic-scale torsional stick-slip behavior in individual nanotubes of tungsten disulfide (WS2). When an external torque is applied to a WS2 nanotube, all its walls initially stick and twist together, until a critical torsion angle, at which the outer wall slips and twists around the inner walls, further undergoing a series of stick-slip torque oscillations. We present a theoretical model based on density-functional-based tight-binding calculations, which explains the torsional stick-slip behavior in terms of a competition between the effects of the in-plane shear stiffness of the WS2 walls and the interwall friction arising from the atomic corrugation of the interaction between adjacent WS2 walls.

Nagapriya, K. S.; Goldbart, Ohad; Kaplan-Ashiri, Ifat; Seifert, Gotthard; Tenne, Reshef; Joselevich, Ernesto

2008-11-01

346

``Quasi-complete'' mechanical model for a double torsion pendulum  

NASA Astrophysics Data System (ADS)

We present a dynamical model for the double torsion pendulum nicknamed “PETER,” where one torsion pendulum hangs in cascade, but off axis, from the other. The dynamics of interest in these devices lies around the torsional resonance, that is at very low frequencies (mHz). However, we find that, in order to properly describe the forced motion of the pendulums, also other modes must be considered, namely swinging and bouncing oscillations of the two suspended masses, that resonate at higher frequencies (Hz). Although the system has obviously 6+6 degrees of freedom, we find that 8 are sufficient for an accurate description of the observed motion. This model produces reliable estimates of the response to generic external disturbances and actuating forces or torques. In particular, we compute the effect of seismic floor motion (“tilt” noise) on the low frequency part of the signal spectra and show that it properly accounts for most of the measured low frequency noise.

De Marchi, Fabrizio; Pucacco, Giuseppe; Bassan, Massimo; De Rosa, Rosario; Di Fiore, Luciano; Garufi, Fabio; Grado, Aniello; Marconi, Lorenzo; Stanga, Ruggero; Stolzi, Francesco; Visco, Massimo

2013-06-01

347

Fourier transform far infrared spectrum of CD 3OD: detailed analysis in the torsional ground state  

NASA Astrophysics Data System (ADS)

High resolution Fourier transform (FT) far infrared (FIR) spectra of CD 3OD isotopomer of methanol have been measured in the range 20-350 cm -1 at a resolution of 0.0017 cm -1 using a Bruker spectrometer. The spectra were recorded in various runs at pressure in the range of 0.2-0.8 mbar both at room temperature and at -60 °C. The spectra show complicated splitting due to strong torsional-rotational interactions in the molecule. Detailed assignments have been achieved mainly for the torsional ground state levels. The assigned transition wavenumbers along with the previously known microwave (MW) [J. Chem. Phys. 23 (1955) 1195; J. Chem. Phys. 56 (1972) 5887; Spectrochim. Acta A 54 (1998) 1375], and recently measured millimeter-wave (MMW) lines [I. Mukhopadhyay, R.A.H. Butler, F.C. DeLucia, E. Herbst, in preparation], were fit to an eighth order Hamiltonian [J. Chem. Phys. 104 (1996) 3914; J. Chem. Phys. 110 (1999) 927; J. Mol. Spectrosc. 193 (1999) 418; Chem. Phys. 263 (2001) 263; Chem. Phys. 257 (2000) 91; Chem. Phys. 280 (2002) 119; Chem. Phys. (2003) in press] with 62 varied parameters. The data set consisted of a total of 3211 transitions with 2959 FIR transitions from the ground torsional state with rotational angular momentum K ranging from 0 to 19 and J ranging from 0 to 45, and 237 MW and MMW transitions. The fit converged with a standard deviation of 0.0007 cm -1 for the FIR component of the data and the standard deviation for the MW and MMW transitions was 560 kHz. The standard deviation for the FIR lines is well compared with the estimated experimental accuracy of 0.0002 cm -1 for clean unblended lines. Here we report the actual measured wavenumbers with their assignments, some of these were not included in the fit. The complete data set fitted is not included here for the sake of economy of space but can be obtained from IM.

Mukhopadhyay, Indranath; Duan, Yun-Bo; Klee, Stefan

2004-06-01

348

A new method for measuring torsional deformity in scoliosis  

PubMed Central

Background The importance of spinal rotational and torsional deformity in the etiology and the management of scoliosis are well-recognized. For measuring the posterior spinal component rotation, Ho's method was reported to be reliable. However, there is no practical method to measure the anterior spinal component rotation. Moreover, there is also no method to quantify the spinal torsional deformity in scoliosis. The goal of this study is to characterize scoliosis and its deformity to hypothesize the etiology and the development of scoliosis, and to establish a new method for the measurement of the vertebral body rotation and spinal torsional deformity in scoliosis using CT scans. Methods Pre-operative CT scans of 25 non-congenital scoliosis patients were recruited and the apical vertebral rotation was measured by a newly developed method and Ho's method. Ho's method adopts the laminae as the rotational landmark. For a new method to measure the apical vertebral rotation, the posterior point just beneath each pedicle was used as a landmark. For quantifying the spinal torsional deformity angle, the rotational angle difference between the two methods was calculated. Results Intraobserver and interobserver reliability analyses showed both methods to be reliable. Apical vertebral rotation revealed 13.9 ± 6.8 (mean ± standard deviation) degrees by the new method and 7.9 ± 6.3 by Ho's method. Right spinal rotation was assigned a positive value. The discrepancy of rotation (6.1 ± 3.9 degrees), meaning that the anterior component rotated more than the posterior component, was considered to express the spinal torsional deformity to the convex side. Conclusions We have developed an easy, reliable and practical method to measure the rotation of the spinal anterior component using a CT scan. Furthermore, we quantified the spinal torsional deformity to the convex side in scoliosis by comparing the rotation between the anterior and posterior components. PMID:21496292

2011-01-01

349

The Angular Momentum of Baryons and Dark Matter Halos Revisited  

NASA Technical Reports Server (NTRS)

Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated by large-scale structure motions deep inside dark matter halos, redistributing it only in the vicinity of the disc.

Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

2011-01-01

350

Fermion condensate from torsion in the reheating era after inflation  

NASA Astrophysics Data System (ADS)

The inclusion of Dirac fermions in Einstein-Cartan gravity leads to a four-fermion interaction mediated by nonpropagating torsion, which can allow for the formation of a Bardeen-Cooper-Schrieffer condensate. By considering a simplified model in 2+1 spacetime dimensions, we show that even without an excess of fermions over antifermions, the nonthermal distribution arising from preheating after inflation can give rise to a fermion condensate generated by torsion. We derive the effective Lagrangian for the spacetime-dependent pair field describing the condensate in the extreme cases of nonrelativistic and massless fermions, and show that it satisfies the Gross-Pitaevski equation for a gapless, propagating mode.

Weller, Joel M.

2013-10-01

351

Coated Fused Silica Fibers for Enhanced Sensitivity Torsion Pendulum  

NASA Technical Reports Server (NTRS)

In order to investigate the fundamental thermal noise limit of a torsion pendulum using a fused silica fiber, we systematically measured and modeled the mechanical losses of thin fused silica fibers coated by electrically conductive thin metal films. Our results indicate that it is possible to achieve a thermal noise limit for coated silica lower by a factor between 3 and 9, depending on the silica diameter, compared to the best tungsten fibers available. This will allow a corresponding increase in sensitivity of torsion pendula used for weak force measurements, including the gravitational constant measurement and ground-based force noise testing for the Laser Interferometer Space Antenna (LISA) mission.

Numata, Kenji; Horowitz, Jordan; Camp, Jordan

2007-01-01

352

Gravitational and torsion waves in linearised teleparallel gravity  

E-print Network

Spin-2, spin-1 and spin-0 modes in linearised teleparallelism are obtained where the totally skew-symmetric complex contortion tensor generates scalar torsion waves and the symmetric contortion in the last two indices generates gravitational waves as gravitational perturbations of flat spacetime with contortion tensor. A gedanken experiment with this gravitational-torsion wave hitting a ring of spinless particles is proposed which allows us to estimate the contortion of the Earth by making use of data from LISA GW detector. This value coincides with previous value obtained by Nitsch in teleparallelism using another type of experiment.

L. C. Garcia de Andrade

2002-06-03

353

High Sensitivity Torsion Balance Tests for LISA Proof Mass Modeling  

E-print Network

We have built a highly sensitive torsion balance to investigate small forces between closely spaced gold coated surfaces. Such forces will occur between the LISA proof mass and its housing. These forces are not well understood and experimental investigations are imperative. We describe our torsion balance and present the noise of the system. A significant contribution to the LISA noise budget at low frequencies is the fluctuation in the surface potential difference between the proof mass and its housing. We present first results of these measurements with our apparatus.

S. Schlamminger; C. A. Hagedorn; M. G. Famulare; S. E. Pollack; J. H. Gundlach

2007-02-08

354

Torsionally excited methanol in hot molecular cloud cores  

NASA Technical Reports Server (NTRS)

Torsionally excited methanol lines were detected in the direction of four galactic molecular cloud regions by means of scans in the 20-24 GHz interval with the Effelsberg 100 m radiotelescope. Transitions in both the first torsionally excited state, with excitation energies of about 450 K, and the ground state were seen in the direction of the hot, molecular cloud cores of the Orion-KL region, W3(OH), NGC 7538 and W51. The emission in Orion originated from a hot region in the southern ridge cloud 4 arcsec from the hot core. The greatest deviations from LTE occurred when a strong compact continuum source was present.

Menten, K. M.; Walmsley, C. M.; Henkel, C.; Wilson, T. L.; Snyder, L. E.; Hollis, J. M.

1986-01-01

355

Inflation in $R + R^2$ Gravity with Torsion  

E-print Network

We examine an inflationary model in $R + R^2$ gravity with torsion, where $R^2$ denotes five independent quadratic curvature invariants; it turns out that only two free parameters remain in this model. We show that the behavior of the scale factor $a(t)$ is determined by two scalar fields, axial torsion $\\chi(t)$ and the totally anti-symmetric curvature $E(t)$, which satisfy two first-order differential equations. Considering $\\dot{\\chi}\\approx 0$ during inflation leads to a power-law inflation: $a \\sim (t+ A)^p$ where $1inflation, $\\chi$ and $E$ will enter into an oscillatory phase.

Chih-Hung Wang; Yu-Huei Wu

2009-02-06

356

Hyperbaric oxygen treatment for unilateral testicular torsion in a child.  

PubMed

Torsion of the testis is a urological emergency most commonly occurring in adolescent boys. Hyperbaric oxygen treatment (HBOT) has been shown to alleviate reperfusion injury in experimental ischaemia of the testis. We report a 13-year-old boy who had prolonged right testicular ischaemia. Despite surgery, the colour of the testis remained poor. He underwent a post-operative course of 10 HBOT over 8 days, with restoration of blood flow on colour Doppler and reduction of oedema. At four-month followup, the testis appeared normal on ultrasonography. To the best of our knowledge, this is the first published case of torsion of the testis treated with HBOT. PMID:25311324

Alp, Bilal Firat; Cebi, Gamze; Ozdemir, Adem; Irkilata, Hasan Cem; Uzun, Günalp

2014-09-01

357

A MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM  

E-print Network

A MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM M.K. Bantel, E of a measurement of G made using a cryogenic torsion pendulum in the `dynamic' (time-of-swing) mode. We have- lation frequency of a thin-plate torsion pendulum due to a pair of ring-shaped source masses positioned

Newman, Riley D.

358

PROGRESS IN THE MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM  

E-print Network

PROGRESS IN THE MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM E a cryogenic torsion pendulum in the "dynamic" (time- of-swing) mode. The total metrology contribution to the G- lation frequency of a thin-plate torsion pendulum due to a pair of ring-shaped source masses positioned

Newman, Riley D.

359

APPLICATION OF WAVELET PACKET ANALYSIS FOR FAULT DETECTION IN ELECTROMECHANICAL SYSTEMS BASED ON TORSIONAL VIBRATION MEASUREMENT  

Microsoft Academic Search

This paper primarily focuses on detecting electrical faults in turbine generator sets by monitoring torsional vibrations with the help of the non-contact measurement technique and analysing the data acquired from torsional vibration meter. Torsional vibrations in shaft trains can be excited by periodic excitation due to a variety of electromagnetic disturbances or unsteady flow in large steam turbine generator sets

X. Li; L. Qu; G. Wen; C. Li

2003-01-01

360

Torsion fatigue behavior of unidirectional carbon\\/epoxy and glass\\/epoxy composites  

Microsoft Academic Search

This paper presents results of the feasibility of carbon\\/epoxy composites (CFRP) as a future helicopter flexbeam material. Torsional behaviors of unidirectional CFRP and glass\\/epoxy composites (GFRP) with the same resin matrix were investigated. The initial torsional rigidity of CFRP was almost identical to that of GFRP. The torsional rigidities calculated using finite element analyses (FEA) agreed with the experimental results:

Toshio Ogasawara; Keiji Onta; Shinji Ogihara; Tomohiro Yokozeki; Eiichi Hara

2009-01-01

361

Mutation of torsion pairs in triangulated categories and its geometric realization  

E-print Network

Mutation of torsion pairs in triangulated categories and its geometric realization Yu Zhou and Bin@mails.tsinghua.edu.cn; bzhu@math.tsinghua.edu.cn Abstract The notion of D-mutation of torsion pairs in triangulated categories is introduced. It is proved that the D-mutation of torsion pairs in triangulated

Zhu, Bin

362

Extension of the torsional crystal viscometer to measurements in the time domain  

Microsoft Academic Search

This paper reports the first wide-ranging application of the free-mode measurement technique to a torsional crystal viscometer. The viscous damping of the fluid on the surface of the crystal is detected in the time domain by observing the freely decaying torsional oscillation of the crystal. Previously, the torsional crystal viscometer was used exclusively in a forced mode of measurement, where

Richard F. Hafer; Arno Laesecke

2003-01-01

363

Seismic Performance of Square Reinforced Concrete Columns under Combined Cyclic Flexural and Torsional Loadings  

Microsoft Academic Search

This article presents an experimental investigation on the behavior of reinforced concrete cantilevered columns subjected to combined cyclic bending and torsional loading. Seven columnar specimens with the same structural properties were tested under various loading conditions: cyclic torsion, cyclic uniaxial bending, and combined cyclic torsion and cyclic uniaxial bending with and without a constant axial compression force. Several combinations of

P. Tirasit; K. Kawashima

2007-01-01

364

Atomistic study of the mechanical response of copper nanowires under torsion  

Microsoft Academic Search

The length, loading rate and thermal effects on the torsional response of hollow copper nanowires are investigated with molecular dynamics simulation. Evolution of atomic configuration is studied, which shows that partial dislocations nucleated from the surfaces accommodate the plastic deformation of the nanowires under torsion. With the increase in torsional angle, necking appears and the corresponding cross-section transforms from a

Shan Jiang; Hongwu Zhang; Yonggang Zheng; Zhen Chen

2009-01-01

365

A torsion test for the study of the large deformation recovery of shape memory polymers  

E-print Network

simply heat, that the recovery of the SMP's original, permanent shape is triggered. The shape recovery1 A torsion test for the study of the large deformation recovery of shape memory polymers Julie recovery, Large deformation, Torsion test, Thermoelasticity, Image analysis ABSTRACT: A torsion device

Paris-Sud XI, Université de

366

SEQUENCES OF RATIONAL TORSIONS ON ABELIAN VARIETIES E. V. Flynn, Mathematical Institute, University of Oxford  

E-print Network

SEQUENCES OF RATIONAL TORSIONS ON ABELIAN VARIETIES E. V. Flynn, Mathematical Institute, University of Oxford Abstract We address the question of how fast the available rational torsion on abelian varieties to provide sequences of curves with rational torsion divisors of or- ders increasing linearly with respect

Flynn, E. Victor

367

Left common basal pyramid torsion following left upper lobectomy/segmentectomy.  

PubMed

Lobar or segmental lung torsion is a severe complication of lung resection. To the best of our knowledge, common basal pyramid torsion has never been reported. We describe a case of left basal pyramid torsion after left upper lobectomy and superior segmentectomy, which was successfully treated by thoracoscopic surgery. PMID:24948781

Wang, Wei-Li; Cheng, Yen-Po; Cheng, Ching-Yuan; Wang, Bing-Yen

2014-06-19

368

A shear-shear torsional beam model for nonlinear aeroelastic analysis of tower buildings  

NASA Astrophysics Data System (ADS)

In this paper, an equivalent one-dimensional beam model immersed in a three-dimensional space is proposed to study the aeroelastic behavior of tower buildings: linear and nonlinear dynamics are analyzed through a simple but realistic physical modeling of the structure and of the load. The beam is internally constrained, so that it is capable to experience shear strains and torsion only. The elasto-geometric and inertial characteristics of the beam are identified from a discrete model of three-dimensional frame, via a homogenization process. The model accounts for the torsional effect induced by the rotation of the floors around the tower axis; the macroscopic shear strain is produced by bending of the columns, accompanied by negligible rotation of the floors. Nonlinear aerodynamic forces are evaluated through the quasi-steady theory. The first aim is to investigate the effect of mechanical and aerodynamic coupling on the critical galloping conditions. Furthermore, the role of aerodynamic nonlinearities on the galloping post-critical behavior is analyzed through a perturbation solution which permits to obtain a reduced one-dimensional dynamical system, capable of capturing the essential dynamics of the problem.

Piccardo, G.; Tubino, F.; Luongo, A.

2014-09-01

369

Torsional electric dipole moment functions calculated for HOOH and ClOOCl.  

PubMed

The periodic torsional, electric dipole moment (EDM) functions ?(?) = ?m = 0pmcos?(m + 1?2)?, of the atmospherically significant molecules HOOH and ClOOCl, have been derived from calculations at the CCSD(T) (coupled-cluster singles and doubles model, plus a noniterative triples correction) level of electronic-structure theory with augmented, correlation-consistent basis sets extrapolated to the approximate complete basis set limit. The ?(?) of HOOH, defined by {pm} = {3.0979, -0.0301, -0.0058} D, is used to calculate squared transition EDMs that compare well with those previously derived using the experimental torsional line intensities. The ?(?) of ClOOCl, defined by ?(?) = {1.1935, 0.1163, 0.1341, -0.0040, -0.0099} D, requires a longer Fourier expansion because, in the range of dihedral angles from the cis (? = 0) to the trans (? = ?) transition structures, three inflection points are found for ClOOCl, but only one for HOOH. The permanent EDM calculated for HOOH, 1.754 D, is in close agreement with the value deduced from experiment. Compared to HOOH, the permanent EDM vector calculated for ClOOCl is directed analogously, but has a significantly smaller magnitude, 0.700 D. PMID:23485292

McGrath, Mark P

2013-03-01

370

Achromatic orbital angular momentum generator  

NASA Astrophysics Data System (ADS)

We describe a novel approach for generating light beams that carry orbital angular momentum (OAM) by means of total internal reflection in an isotropic medium. A continuous space-varying cylindrically symmetric reflector, in the form of two glued hollow axicons, is used to introduce a nonuniform rotation of polarization into a linearly polarized input beam. This device acts as a full spin-to-orbital angular momentum convertor. It functions by switching the helicity of the incoming beam?s polarization, and by conservation of total angular momentum thereby generates a well-defined value of OAM. Our device is broadband, since the phase shift due to total internal reflection is nearly independent of wavelength. We verify the broad-band behaviour by measuring the conversion efficiency of the device for three different wavelengths corresponding to the RGB colours, red, green and blue. An average conversion efficiency of 95% for these three different wavelengths is observed. This device may find applications in imaging from micro- to astronomical systems where a white vortex beam is needed.

Bouchard, Frédéric; Mand, Harjaspreet; Mirhosseini, Mohammad; Karimi, Ebrahim; Boyd, Robert W.

2014-12-01

371

Spin Angular Momentum Imparted by Gravitational Waves  

E-print Network

Following the demonstration that gravitational waves impart linear momentum, it is argued that if they are polarized they should impart angular momentum to appropriately placed 'test rods' in their path. A general formula for this angular momentum is obtained and used to provide expressions for the angular momentum imparted by plane and cylindrical gravitational waves.

M Sharif

2007-01-23

372

The angular momentum of the Oort cloud  

Microsoft Academic Search

An evaluation is made of the work of Marochnik et al. (1988), which estimated that the angular momentum of the Oort cloud is 2-3 orders of magnitude greater than the planetary system's total angular momentum. It is noted that most of the angular momentum in the currently observed Oort cloud is the result of the effects of external perturbers over

P Weissman

1991-01-01

373

Texture Development During Equal Channel Angular Forging of BCC Metals  

SciTech Connect

Equal channel angular forging (ECAF) has been proposed as a severe plastic deformation technique for processing metals, alloys, and composites [e.g. Segal, 1995] (Fig. 1). The technique offers two capabilities of practical interest: a high degree of strain can be introduced with no change in the cross-sectional dimensions of the work-piece, hence, even greater strains can be introduced by re-inserting the work-piece for further deformation during subsequent passes through the ECAF die. Additionally, the deformation is accomplished by simple shear (like torsion of a short tube) on a plane whose orientation, with respect to prior deformations, can be controlled by varying the processing route. There is a nomenclature that has developed in the literature for the typical processing routes: A: no rotations; B{sub A}: 90 degrees CW (clockwise), 90 degrees CCW (counterclockwise), 9O degrees CW, 90 degrees CCW...; Bc: 90 degrees CW, 90 degrees CW, 90 degrees CW...; and C: 180 degrees, 18 0 degrees.... The impact of processing route on the subsequent microstructure [Ferasse, Segal, Hartwig and Goforth, 1997; Iwahashi, Horita, Nemoto and Langdon, 1996] and texture [Gibbs, Hartwig, Cornwell, Goforth and Payzant, 1998] has been the subject of numerous experimental studies.

Agnew, S.R.

1999-08-08

374

Quadruple LVDT local rotational displacement measurement in torsional shear tests  

Microsoft Academic Search

Experience has shown that to obtain pre-failure deformability of geomaterials in laboratory element tests, it is imperative to make local strain measurements. For torsional shear tests, the local measurement is complicated by coupling of the axial, radial, and rotational movement experienced by the soil specimen during shear. The rotational displacement must be isolated from other modes of movement for the

An-Bin Huang; Yao-Tao Huang; Yuan-Yu Tai; Fu-Jen Ho; Jun-Min Chang

2007-01-01

375

Quaternionic Torsion Geometry, Superconformal Symmetry and T-duality  

SciTech Connect

HyperKaehler metrics with torsion (HKT metrics) are constructed via superconformal symmetry. It is shown how T-duality interpreted as a twist construction for circle actions provides a number of compact simply-connected examples. Further applications of the twist construction are discussed to obtain compact simply-connected HKT manifolds with few symmetries and to construct all HKT nilmanifolds.

Swann, Andrew [Department of Mathematics and Computer Science, University of Southern Denmark, Campusvej 55, 5230 Odense M (Denmark)

2009-02-02

376

Study of properties of sand asphalt using a torsional rheometer  

E-print Network

. In this work we have used the same Torsional Rheometer with some minor modifications in the design to measure some general properties of Sand Asphalt mixtures. Sand Asphalt mixtures, due to their non-linear viscoelastic character, exhibit `normal stress effects...

Kasula, Lavan Kumar Reddy

2004-11-15

377

Residual strain evolution in steel samples: tension versus torsion  

Microsoft Academic Search

Torsion provides a unique opportunity to probe mechanical behavior of materials subjected to pure state of shear stress. In this research, identical steel alloy (12L14) hollow cylinder samples are subjected to predetermined amounts of plastic axial and shear strain such that their octahedral shear strain (an invariant) are identical for comparison. Measurements were made at the residual stress measuring facility

J. R. Bunn; D. Penumadu; C. R. Hubbard

2010-01-01

378

Torsion of an Epiploic Appendix Pretending as Acute Appendicitis  

PubMed Central

Torsion of an epiploic appendix is a rare surgical entity. Its unusual symptomatology, wide variation in physical findings and the absence of helpful laboratory and radiological studies makes it very difficult to diagnose pre-operatively. This is a report of this rare entity found in a patient upon diagnostic laparoscopy performed for suspected acute appendicitis. PMID:22043343

Malik, Kamran Ahmad

2010-01-01

379

Simulation of the behaviour of FCC polycrystals during reversed torsion  

Microsoft Academic Search

Taylor-type polycrystal plasticity models with various single slip hardening laws are evaluated by studying the large strain behaviour of FCC polycrystals during reversed torsion. The hardening laws considered include the model of Asaro and Needleman (“Texture Development and Strain Hardening in Rate Dependent Polycrystals,” Acta Metall. (1985), 34, 1553) as well as a power-law and an exponential version of that,

P. D. Wu; K. W. Neale; E. Van der Giessen

1996-01-01

380

A measurement of G with a cryogenic torsion pendulum.  

PubMed

A measurement of Newton's gravitational constant G has been made with a cryogenic torsion pendulum operating below 4 K in a dynamic mode in which G is determined from the change in torsional period when a field source mass is moved between two orientations. The source mass was a pair of copper rings that produced an extremely uniform gravitational field gradient, whereas the pendulum was a thin fused silica plate, a combination that minimized the measurement's sensitivity to error in pendulum placement. The measurement was made using an as-drawn CuBe torsion fibre, a heat-treated CuBe fibre, and an as-drawn Al5056 fibre. The pendulum operated with a set of different large torsional amplitudes. The three fibres yielded high Q-values: 82?000, 120?000 and 164?000, minimizing experimental bias from fibre anelasticity. G-values found with the three fibres are, respectively: {6.67435(10),6.67408(15),6.67455(13)}×10(-11)?m(3)?kg(-1)?s(-2), with corresponding uncertainties 14, 22 and 20?ppm. Relative to the CODATA2010 G-value, these are higher by 77, 37 and 107?ppm, respectively. The unweighted average of the three G-values, with the unweighted average of their uncertainties, is 6.67433(13)×10(-11)?m(3)?kg(-1)?s(-2) (19?ppm). PMID:25202000

Newman, Riley; Bantel, Michael; Berg, Eric; Cross, William

2014-10-13

381

A circumferential crack in a cylindrical shell under torsion.  

NASA Technical Reports Server (NTRS)

The fully antisymmetric problem for a cylindrical shell with a circumferential crack is considered. The solution of the problem is reduced to that of a system of singular integral equations of the first kind. As an example the torsion of the cylinder is discussed and membrane and bending components of the stress intensity factor ratio are given.

Erdogan, F.; Ratwani, M.

1972-01-01

382

Secondary Stresses in Open Box Beams Subjected to Torsion  

NASA Technical Reports Server (NTRS)

In open box beams subjected to torsion, secondary stresses arise owing to lateral bending of the spar caps. The present paper outlines a simple method for estimating the magnitude of these stresses and gives the results of tests of an open box beam in the neighborhood of a discontinuity where the cover changed from the top to the bottom of the box.

Kuhn, Paul; Batdorf, S. B.; Brilmyer, Harold G

1944-01-01

383

Compressive and torsional behaviour of Kevlar 49 fibre  

Microsoft Academic Search

The mechanical anisotropy of an aromatic polyamide fibre, Kevlar 49, was studied in tension, compression and torsion. A new technique involved applying small and defined compressive strains to filaments by bonding them to one side of a beam which is subsequently bent to compress the fibres. Using scanning electron and optical microscopy, fibres were shown to form regularly-spaced helical kink

S. J. Deteresa; S. R. Allen; R. J. Farris; R. S. Porter

1984-01-01

384

A modified split Hopkinson torsional bar in studying shear localization  

Microsoft Academic Search

A modified split Hopkinson torsional bar (SHTB) is introduced to eliminate the effect of the loading reverberation of the standard SHTB on the study of evolution of shear localization. The effect, the cause and the method by which to eliminate loading wave reverberation are carefully analysed and discussed. By means of the modified apparatus, the post-mortem observation of tested specimens

Q. Xue; L. T. Shen; Y. L. Bai

1995-01-01

385

An analytical model of a longitudinal-torsional ultrasonic transducer  

Microsoft Academic Search

The combination of longitudinal and torsional (LT) vibrations at high frequencies finds many applications such as ultrasonic drilling, ultrasonic welding, and ultrasonic motors. The LT mode can be obtained by modifications to the design of a standard bolted Langevin ultrasonic transducer driven by an axially poled piezoceramic stack, by a technique that degenerates the longitudinal mode to an LT motion

Hassan Al-Budairi; Margaret Lucas

2012-01-01

386

On Updating Torsion Angles of Molecular Conformations Vicky Choi*  

E-print Network

- Hartenberg local frames, and the atom-group local frames. On the basis of their implementations, they showed that the atom-group local frames are more efficient than the other two. In this paper, by expressing the torsion quaternions, are as efficient as the atom-group local frames and, thus, have the advantage of avoiding

Choi, Vicky

387

Nonlinear Analysis of Reinforced Concrete Beams Under Pure Torsion  

NASA Astrophysics Data System (ADS)

A nonlinear finite element analysis is conducted using ANSYS-V10 finite element package on six reinforced concrete cantilever beams having different length vary from 0.5 to 3 m with 0.5 m increments and subjected to a concentrated torque at the free end. The beams are designed to carry the same torque. The study emphasize on the effect of beam length (span to depth ratio) on the torsional strength and behavior of reinforced concrete rectangular beams and the effectiveness of the torsional reinforcement in the pre and post cracking stages of loading. It was found that beams with span/depth ratio equal to or more than 4 have the same reserved torsional strength and less than those with smaller ratio, keeping the cross section and torsional reinforcements constant for all the beams. Before cracking stresses in transverse and longitudinal reinforcement are almost negligible and it is far below the yield stress even at the post cracking stages. Reinforcement attained yielding only at ultimate torque and after the wide spread of cracks in the shorter beam.

Najim Mahmood, Mohammad

388

34. VERTICAL AND TORSIONAL MOTION VIEWED FROM EAST TOWER, 7 ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

34. VERTICAL AND TORSIONAL MOTION VIEWED FROM EAST TOWER, 7 NOVEMBER 1940, FROM 16MN FILM SHOT BY PROFESSOR F.B. FARQUHARSON, UNIVERSITY OF WASHINGTON. (LABORATORY STUDIES ON THE TACOMA NARROWS BRIDGE, AT UNIVERSITY OF WASHINGTON (SEATTLE: UNIVERSITY OF WASHINGTON, DEPARTMENT OF CIVIL ENGINEERING, 1941) - Tacoma Narrows Bridge, Spanning Narrows at State Route 16, Tacoma, Pierce County, WA

389

An abnormal mode of torsion pendulum and its suppression  

NASA Astrophysics Data System (ADS)

The numerical solution of non-linear equations shows that the abnormal mode observed in our torsion pendulum experiments is an intrinsic mode of the pendulum. Further analysis shows that the amplitude of abnormal mode increasing with of swing modes can be suppressed with a magnetic damper effectively.

Tu, Ying; Zhao, Liang; Liu, Qi; Ye, Hong-Ling; Luo, Jun

2004-11-01

390

Endomorphisms of countable direct sums of torsion complete groups  

Microsoft Academic Search

This paper is a further study of those abelian p-groups G whose ring of endomorphisms is generated by its group of automorphisms. It was shown in [1 ] that if G is a direct sum of countable p-groups or a torsion complete p-group, p # 2, then each endomorphism of G was a sum of two automorphisms of G. In

F. Castagna

1972-01-01

391

Development of a high-resolution micro-torsion tester for measuring the shear modulus of metallic glass fibers  

NASA Astrophysics Data System (ADS)

A high-resolution micro-torsion tester is developed based on electromagnetism, and the shear modulus of metallic glass fiber (Pd40Cu30Ni10P20) is measured using this tester. The torque is measured by a coil-magnet component and the rotation angle is measured by an inductive angular transducer. The calibration results show that the torque capacity of this tester is 1.1? × ?10?3?N m with resolution of 3? × ?10?8?N m and the rotation angle capacity is 90° with a resolution of 0.01°. A set of metallic glass fibers, with diameter of about 90?µm, are tested using this tester. The average shear modulus is obtained as 20.2?GPa (±6%).

Dai, Y. J.; Huan, Y.; Gao, M.; Dong, J.; Liu, W.; Pan, M. X.; Wang, W. H.; Bi, Z. L.

2015-02-01

392

Piezoelectric ceramic assembly tubes for torsional actuators  

NASA Astrophysics Data System (ADS)

The efforts described here are intended to provide a basis for the utilization of novel piezoelectric actuators in smart materials and structures. The actuator design developed in this study is a segmented, piezoelectric tube, with the individual segments driven in a d15 shear mode. The PZT-5A tubes were cut longitudinally in to an even number of equal slender segments. These slender segments were poled individually along their length using a continuous poling technique developed at NRL. The polarization of the poled segments alternates in direction between adjacent segments. The segments were reassembled with a conductive epoxy so that it serves as both joint and electrode. The assembled actuator tubes were evaluated by applying electric field normal to the polarization direction of the segments, demonstrating proof of concept. These solid state prototype devices were driven to precise angular displacement and torque output. Reliability test, including both fatigue and mechanical loading of the device, were conducted. In conjunction with this effort, numerical computation analyses were performed with respect to structural integrity versus segment joint thickness, and the relative effect of cylindrical versus polygonal configurations. These studies facilitated the successful production of prototypes. Projected actuator outputs based on electromechanical test results are also discussed in terms of requirements for noise and vibration control of helicopter rotor blades.

Kim, Chulho; Glazounov, Alexandre E.; Flippen, Luther D.; Pattnaik, Amitav; Zhang, Qi Ming; Lewis, David, III

1999-07-01

393

Torsion Bounds from CP Violation ?2-DYNAMO in Axion-Photon Cosmic Plasma  

NASA Astrophysics Data System (ADS)

Years ago Mohanty and Sarkar [Phys. Lett. B 433, 424 (1998)] have placed bounds on torsion mass from K meson physics. In this paper, associating torsion to axions a la Campanelli et al. [Phys. Rev. D 72, 123001 (2005)], it is shown that it is possible to place limits on spacetime torsion by considering an efficient ?2-dynamo CP violation term. Therefore instead of Kostelecky et al. [Phys. Rev. Lett. 100, 111102 (2008)] torsion bounds from Lorentz violation, here torsion bounds are obtained from CP violation through dynamo magnetic field amplification. It is also shown that oscillating photon-axion frequency peak is reduced to 10-7 Hz due to torsion mass (or Planck mass when torsion does not propagate) contribution to the photon-axion-torsion action. Though torsion does not couple to electromagnetic fields at classical level, it does at the quantum level. Recently, Garcia de Andrade [Phys. Lett. B 468, 28 (2011)] has shown that the photon sector of Lorentz violation (LV) Lagrangian leads to linear nonstandard Maxwell equations where the magnetic field decays slower giving rise to a seed for galactic dynamos. Torsion constraints of the order of K0?10-42 GeV can be obtained which are more stringent than the value obtained by Kostelecky et al. A lower bound for the existence of galactic dynamos is obtained for torsion as K0?10-37 GeV.

Garcia de Andrade, L. C.

394

Two-axis angular effector  

DOEpatents

A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.

Vaughn, Mark R. (Albuquerque, NM); Robinett, III, Rush D. (Tijeras, NM); Phelan, John R. (Albuquerque, NM); Van Zuiden, Don M. (Albuquerque, NM)

1997-01-21

395

Variable Distance Angular Symbology Reader  

NASA Technical Reports Server (NTRS)

A variable distance angular symbology, reader utilizes at least one light source to direct light through a beam splitter and onto a target. A target may be angled relative to the impinging light beam up to and maybe even greater than 45deg. A reflected beam from the target passes through the beam splitter and is preferably directed 90deg relative to the light source through a telecentric lens to a scanner which records an image of the target such as a direct part marking code.

Schramm, Harry F., Jr. (Inventor); Corder, Eric L. (Inventor)

2006-01-01

396

Form factors and non-local multiplicative anomaly for fermions with background torsion  

NASA Astrophysics Data System (ADS)

We analyse the multiplicative anomaly (MA) in the case of quantized massive fermions coupled to a background torsion. The one-loop effective action (EA) can be expressed in terms of the logarithm of the determinant of the appropriate first-order differential operator acting in the spinors space. Simple algebraic manipulations on determinants must be used in order to apply properly the Schwinger-DeWitt technique, or even the covariant perturbation theory (Barvinsky and Vilkovisky, 1990), which is used in the present work. By this method, we calculate the finite non-local quantum corrections, and analyse explicitly the breakdown of those algebraic manipulations on determinants, called by MA. This feature comes from the finite non-local EA, but does not affect the results in the UV limit, in particular, the beta-functions. Similar results were also obtained in previous papers but for different external fields (QED and scalar field).

de Berredo-Peixoto, G.; Espinosa Maicá, A.

2014-06-01

397

On a finite-state inflow application to flap-lag-torsion damping in hover  

NASA Technical Reports Server (NTRS)

An aerodynamic model with a coupled set of generalized dynamic wake equations and hybrid equations of motion for an elastic blade are applied here to a two-blade untwisted stiff in-plane hingeless small-scale model rotor with torsionally soft blades. Blade root offset, precone, blade droop, pitch control stiffness, and blade pitch angle are included in the model rotor. Numerical results show that 3D tip relief effects within the nonuniform steady-state inflow are significant to predict steady-state aerodynamic loads and blade deflections. Eigenvalue results confirm the importance of unsteady 3D aerodynamics in predicting lead-lag damping and frequency. Eigenvector analysis correlations reinforced qualitative and quantitative shortcomings associated with quasi-steady 2D aerodynamic theory for aeroelastic applications in hover.

De Andrade, Donizeti; Peters, David A.

1992-01-01

398

Form factors and non-local Multiplicative Anomaly for fermions with background torsion  

E-print Network

We analyse the Multiplicative Anomaly (MA) in the case of quantized massive fermions coupled to a background torsion. The one-loop Effective Action (EA) can be expressed in terms of the logarithm of determinant of the appropriate first-order differential operator acting in the spinors space. Simple algebraic manipulations on determinants must be used in order to apply properly the Schwinger-DeWitt technique, or even the covariant perturbation theory (Barvinsky and Vilkovisky, 1990), which is used in the present work. By this method, we calculate the finite non-local quantum corrections, and analyse explicitly the breakdown of those algebraic manipulations on determinants, called by MA. This feature comes from the finite non-local EA, but does not affect the results in the UV limit, in particular the beta-functions. Similar results was also obtained in previous papers but for different external fields (QED and scalar field).

Guilherme de Berredo-Peixoto; Alan E. Maicá

2014-02-20

399

The effects of lateral-torsional coupling on the nonlinear dynamic behavior of a rotating continuous flexible shaft-disk system with rub-impact  

NASA Astrophysics Data System (ADS)

This study investigates the lateral-torsional coupling effects on the nonlinear dynamic behavior of a rotating flexible shaft-disk system. The system is modeled as a continuous shaft with a rigid disk in its mid span. Coriolis and centrifugal effects due to shaft flexibility are also included. The partial differential equations of motion are extracted under the Rayleigh beam theory. The assumed mode method is used to discretize partial differential equations and the resulting equations are solved via numerical methods. The analytical methods used in this work include time series, phase plane portrait, power spectrum, Poincaré map, bifurcation diagrams, and Lyapunov exponents. The main objective of the present study is to investigate the torsional coupling effects on the chaotic vibration behavior of a system. Periodic, sub-harmonic, quasi-periodic, and chaotic states can be observed for cases with and without torsional effects. As demonstrated, inclusion of the torsional-lateral coupling effects can primarily change the speed ratios at which rub-impact occurs. Also, substantial differences are shown to exist in the nonlinear dynamic behavior of the system in the two cases.

Khanlo, H. M.; Ghayour, M.; Ziaei-Rad, S.

2013-06-01

400

Polarization-insensitive and thin stereometamaterial with broadband angular absorption for the oblique incidence  

NASA Astrophysics Data System (ADS)

A novel and thin stereometamaterial composed of an orthogonal double-split-ring microstructure, a plane ground with five hemispherical metric surfaces and a coating substrate is proposed and demonstrated to obtain a polarization-insensitive and broadband angular absorption. The mechanism of absorbing electromagnetic wave has been interpreted and investigated by the anti-reflection theory and the surface loss density for the oblique incidence. The absorbing characters have been improved by the five hemispherical metric grounds. The insensitive polarization is proved by the surface current distributions and the angular absorption. It exhibits a broadband angular absorbing range from 6.05 to 13 GHz with the absorption larger than 80 % at the incident angles of 45° theoretically and experimentally. For verification, a stereometamaterial sample with 576 cells is fabricated and measured. Consistent numerical and experimental results have both validated the broadband angular absorption. The design yields advantages of polarized insensitivity, broadband angular absorption and thin microstructure.

Li, Si-Jia; Gao, Jun; Cao, Xiang-Yu; Zheng, Gui

2015-01-01

401

Isolated tubal torsion at menarche- a case report  

PubMed

Background: Adnexal torsion is a well-recognized cause of acute pelvic pain. Isolated tubal torsion with ovarian sparing has certainly been documented, but is uncommon. Although risk factors for the latter include a menstrual period, menarche in particular is not known to predispose a patient to this event. Severe unilateral pelvic pain with first menses is more likely to herald a congenital mullerian anomaly and cryptomenorrhea, particularly when accompanied by a pelvic mass. We present a case of tubal torsion where a coincidental, yet misleading temporal relation to menarche led to a delay in laparoscopy and ultimate diagnosis.Case: KG, an eleven-year-old female, experienced severe right-sided dysmenorrhea with her first and second menses in August and September 1999 respectively. Between episodes, pain, although still present, was more tolerable and the patient never required hospitalization. Ultrasound revealed a lobulated inhomogeneous mass posterior to the uterus and extending from one normal ovary to the other (Figures). MRI further described the mass as pseudoencapsulated with inhomogeneous areas of high attenuation on T1 and T2 images (Figures). Findings were consistent with an endometrioma, but admittedly could have represented a hemorrhagic cystic mass. No definite mullerian anomaly was seen to explain advanced endometriosis, but two focal areas within the endometrial canal raised the possibility of a uterine septum. Examination of the patient (one week after presentation) was not very helpful although she was pubertal, did have a hymenal septum and was mildly tender on bimanual examination in the Pouch of Douglas. The patient had been started on continuous oral contraceptives while undergoing investigations. Pain only recurred during an episode of break-through bleeding. Ultimately she came to laparoscopy and hysteroscopy where chronic right tubal torsion and necrosis was identified with an inflammatory/hemorrhagic reaction in the pelvis (Photos). There were no identifiable fimbria of the right tube which was densely adherent distally to perirectal fat (Photo). No obvious precipitant was found. Laparoscopic lysis of adhesions and right distal salpingectomy was performed (Photo). Her uterine cavity was in fact normal (Photo)Conclusion: Whether or not this patient's right tube was originally normal will never be known. Congenital abnormalities of fallopian tubes do occur and can predispose to torsion. Nonetheless, adnexal torsion must always be kept in mind whenever a woman presents with unilateral pelvic pain. Early diagnosis is paramount in children and women of reproductive age in order to improve the likelihood of adnexal salvage and future fertility. A "gold-standard" radiological investigative tool continues to elude us. Laparoscopy, albeit more invasive, remains an invaluable procedure in this context with relatively low morbidity as compared to the consequences of delayed diagnosis. PMID:10869984

Jamieson; Soboleski

2000-05-01

402

Angular Momentum Generation from Holographic Chern-Simons Models  

E-print Network

We study parity-violating effects, particularly the generation of angular momentum density and its relation to the parity-odd and dissipationless transport coefficient Hall viscosity, in strongly-coupled quantum fluid systems in 2+1 dimensions using holographic method. We employ a class of 3+1-dimensional holographic models of Einstein-Maxwell system with gauge and gravitational Chern-Simons terms coupled to a dynamical scalar field. The scalar can condensate and break the parity spontaneously. We find that when the scalar condensates, a non-vanishing angular momentum density and an associated edge current are generated, and they receive contributions from both gauge and gravitational Chern-Simons terms. The angular momentum density does not satisfy a membrane paradigm form because the vector mode fluctuations from which it is calculated are effectively massive. On the other hand, the emergence of Hall viscosity is a consequence of the gravitational Chern-Simons term alone and it has membrane paradigm form. We present both general analytic results and numeric results which take back-reactions into account. The ratio between Hall viscosity and angular momentum density resulting from the gravitational Chern-Simons term has in general a deviation from the universal 1/2 value obtained from field theory and condensed matter physics.

Chaolun Wu

2014-12-22

403

Optical vortices in twisted optical fibres with torsional stress  

NASA Astrophysics Data System (ADS)

We solve the vector wave equation for twisted weakly guiding optical fibres using perturbation theory. It is demonstrated that the core modes of such fibres with azimuthal number l = 1 are presented by two circularly polarized optical vortices (OVs) with the unit topological charge and conventional TE and TM modes. We have also shown that the modes with l>1 are formed by the circularly polarized OVs with the higher-order topological charges. All OVs are found to be robust under small external perturbations of the fibre's parameters. The corresponding propagation constants have been found and it is shown that the corrections induced by the twist are proportional to the total angular momentum of the OV. It is shown that, under certain conditions, the propagation through the twisted fibre of a linearly polarized OV with the unit topological charge is accompanied by rotation of the polarization plane, while the propagation of a circularly polarized Hermit-Gauss mode HG01 is accompanied by rotation of the intensity pattern.

Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

2008-09-01

404

Continuous Control and the Algebraic L-theory Assembly Map.  

E-print Network

In this work, the assembly map in L-theory for the family of finite subgroups is proven to be a split injection for a class of groups. Groups in this class, including virtually polycyclic groups, have universal spaces that satisfy certain geometric conditions. The proof follows the method developed by Carlsson-Pedersen to split the assembly map in the case of torsion free groups. Here, the continuously controlled techniques and results are extended to handle groups with torsion.

David Rosenthal.; no. 2; 193--209

405

Preliminary determination of Newtonian gravitational constant with angular acceleration feedback method.  

PubMed

This paper describes the preliminary measurement of the Newtonian gravitational constant G with the angular acceleration feedback method at HUST. The apparatus has been built, and preliminary measurement performed, to test all aspects of the experimental design, particularly the feedback function, which was recently discussed in detail by Quan et al. The experimental results show that the residual twist angle of the torsion pendulum at the signal frequency introduces 0.4?ppm to the value of G. The relative uncertainty of the angular acceleration of the turntable is approximately 100?ppm, which is mainly limited by the stability of the apparatus. Therefore, the experiment has been modified with three features: (i) the height of the apparatus is reduced almost by half, (ii) the aluminium shelves were replaced with shelves made from ultra-low expansion material and (iii) a perfect compensation of the laboratory-fixed gravitational background will be carried out. With these improvements, the angular acceleration is expected to be determined with an uncertainty of better than 10?ppm, and a reliable value of G with 20?ppm or below will be obtained in the near future. PMID:25201996

Xue, Chao; Quan, Li-Di; Yang, Shan-Qing; Wang, Bing-Peng; Wu, Jun-Fei; Shao, Cheng-Gang; Tu, Liang-Cheng; Milyukov, Vadim; Luo, Jun

2014-10-13

406

Effect of inner ring centrifugal displacement on the dynamic characteristics of high-speed angular contact ball bearing  

Microsoft Academic Search

According to the elastic theory the calculating formulas of inner ring centrifugal displacement are inferred, in consideration of inner ring centrifugal displacement the basic equations of angular contact ball bearing are set up, effect of inner ring centrifugal displacement on the dynamic characteristics of high-speed angular contact ball bearings are studied. The results from taking 7012C bearing as an example

Wang Bao-min; Mei Xue-song; Hu Chi-bing; Wu Zai-xin

2010-01-01

407

Thermal noise limit in measuring the gravitational constant G using the angular acceleration method and the dynamic deflection method  

NASA Astrophysics Data System (ADS)

A general comparison is made between two methods of measuring the gravitational constant G. The angular acceleration method can avoid the anelasticity effect since the torsion fiber is not twisted. The dynamic deflection method is similar in principle but it does not use feedback, therefore a major noise introduced by the feedback control system in the angular acceleration method can be avoided. Both methods have their advantages and can be performed with the same device. Based on different expressions of G, we have expressed the signal-to-noise ratio and calculated the thermal noise limit for both methods. In order to get a lower thermal noise limit, the dynamic deflection method should avoid resonance.

Luo, Jie; Shao, Cheng-Gang; Tian, Yuan; Wang, Dian-Hong

2013-09-01

408

High angular resolution neutron interferometry.  

PubMed

The currently largest perfect-crystal neutron interferometer with six beam splitters and two interference loops offers novel applications in neutron interferometry. The two additional lamellas can be used for quantitative measurements of a phase shift due to crystal diffraction in the vicinity of a Bragg condition. The arising phase, referred to as "Laue phase," reveals an extreme angular sensitivity, which allows the detection of beam deflections of the order of 10(-6) s of arc. Furthermore, a precise measurement of the Laue phase at different reflections might constitute an interesting opportunity for the extraction of fundamental quantities like the neutron-electron scattering length, gravitational short-range interactions in the sub-micron range and the Debye Waller factor. For that purpose several harmonics can be utilized at the interferometer instrument ILL-S18. PMID:21731155

Zawisky, M; Springer, J; Lemmel, H

2011-04-01

409

Fermion condensate from torsion in the reheating era after inflation  

E-print Network

The inclusion of Dirac fermions in Einstein-Cartan gravity leads to a four-fermion interaction mediated by non-propagating torsion, which can allow for the formation of a Bardeen-Cooper-Schrieffer condensate. By considering a simplified model in 2+1 spacetime dimensions, we show that even without an excess of fermions over antifermions, the nonthermal distribution arising from preheating after inflation can give rise to a fermion condensate generated by torsion. We derive the effective Lagrangian for the spacetime-dependent pair field describing the condensate in the extreme cases of nonrelativistic and massless fermions, and show that it satisfies the Gross-Pitaevski equation for a gapless, propagating mode.

Weller, Joel M

2013-01-01

410

Dark energy fifth forces in torsion pendulum experiments  

E-print Network

The chameleon scalar field is a matter-coupled dark energy candidate whose nonlinear self-interaction partially screens its fifth force at laboratory scales. Nevertheless, small-scale experiments such as the torsion pendulum can provide powerful constraints on chameleon models. Here we develop a simple approximation for computing chameleon fifth forces in torsion pendulum experiments such as Eot-Wash. We show that our approximation agrees well with published constraints on the quartic chameleon, and we use it to extend these constraints to a much wider range of models. Finally, we forecast the constraints which will result from the next-generation Eot-Wash experiment, and show that this experiment will exclude a wide range of quantum-stable models.

Amol Upadhye

2012-10-22

411

Why has spacetime torsion such negligible effect on the Universe?  

NASA Astrophysics Data System (ADS)

We attempt an answer to the question as to why the evolution of a four-dimensional universe is governed by spacetime curvature but not torsion. An answer is found if there is an additional compact spacelike dimension with a warped geometry, with torsion caused by a Kalb-Ramond (KR) antisymmetric tensor field in the bulk. Starting from a Randall-Sundrum type of warped extra dimension, and including the inevitable backreaction ensuing from the radius stabilization mechanism, we show that there is always an extra exponential suppression of the KR field on the four-dimensional projection that constitutes our visible Universe. The backreaction is found to facilitate the process of such suppression.

Das, Ashmita; Mukhopadhyaya, Biswarup; SenGupta, Soumitra

2014-11-01

412

Lighter diesel engines add new twist to torsional vibration  

SciTech Connect

Torsional vibration remains a relatively unfamiliar science. Most diesel equipment users, as well as many engine designers and OEM service people, do not feel this problem is significant. It may be that most users have simply become conditioned to replacing broken crankshafts, spline shafts, couplings, bearings, gears and seals as the normal consequence of engine operations, and continue repairing the breakage without pressing suppliers for a more permanent, preventive solution. The following examines sources of torsional vibration problems, and reviews the role coupling technology can play in minimizing these problems as smaller, lighter-weight engines become more popular. People concerned with drive-train mechanics generally understand the coupling as a power transmitting, shock absorbing and misalignment compensating device. However, many do not recognize its role in damping vibration and tuning the engine-driven system to shift destructive resonance speeds away from the engine operating RPM range, or the reason why such tuning is needed in the first place.

Mahan, J. (Lovejoy, Inc., Downers Grove, IL (United States))

1994-07-01

413

Omental torsion in a captive polar bear (Ursus maritimus).  

PubMed

This is the first case report of an omental torsion in a polar bear (Ursus maritimus). A captive, 23-yr-old, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center with a 2-day history of lethargy, depression, and vomiting. Abdominal ultrasound identified large amounts of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick serosanguinous fluid compatible with a hemoabdomen. An exploratory laparotomy revealed a large amount of malodorous, serosanguineous fluid and multiple necrotic blood clots associated with a torsion of the greater omentum and rupture of a branch of the omental artery. A partial omentectomy was performed to remove the necrotic tissue and the abdomen was copiously lavaged. The polar bear recovered successfully and is reported to be clinically well 6 mo later. This condition should be considered as a differential in bears with clinical signs of intestinal obstruction and hemoabdomen. PMID:24712179

Mendez-Angulo, Jose L; Funes, Francisco J; Trent, Ava M; Willette, Michelle; Woodhouse, Kerry; Renier, Anna C

2014-03-01

414

MAGNETOSEISMOLOGY: EIGENMODES OF TORSIONAL ALFVEN WAVES IN STRATIFIED SOLAR WAVEGUIDES  

SciTech Connect

There have recently been significant claims of Alfven wave observation in the solar chromosphere and corona. We investigate how the radial and longitudinal plasma structuring affects the observational properties of torsional Alfven waves in magnetic flux tubes for the purposes of solar magnetoseismology. The governing magnetohydrodynamic equations of these waves in axisymmetric flux tubes of arbitrary radial and axial plasma structuring are derived and we study their observable properties for various equilibria in both thin and finite-width magnetic flux tubes. For thin flux tubes, it is demonstrated that observation of the eigenmodes of torsional Alfven waves can provide temperature diagnostics of both the internal and surrounding plasma. In the finite-width flux tube regime, it is shown that these waves are the ideal magnetoseismological tool for probing radial plasma inhomogeneity in solar waveguides.

Verth, G.; Goossens, M. [Centrum voor Plasma Astrofysica, KU Leuven, Celestijnenlaan 200B, 3001 Heverlee (Belgium); Erdelyi, R., E-mail: Gary.Verth@wis.kuleuven.b, E-mail: Marcel.Goossens@wis.kuleuven.b, E-mail: robertus@sheffield.ac.u [Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2010-05-10

415

The Torsion of Members Having Sections Common in Aircraft Construction  

NASA Technical Reports Server (NTRS)

Within recent years a great variety of approximate torsion formulas and drafting-room processes have been advocated. In some of these, especially where mathematical considerations are involved, the results are extremely complex and are not generally intelligible to engineers. The principal object of this investigation was to determine by experiment and theoretical investigation how accurate the more common of these formulas are and on what assumptions they are founded and, if none of the proposed methods proved to be reasonable accurate in practice, to produce simple, practical formulas from reasonably correct assumptions, backed by experiment. A second object was to collect in readily accessible form the most useful of known results for the more common sections. Formulas for all the important solid sections that have yielded to mathematical treatment are listed. Then follows a discussion of the torsion of tubular rods with formulas both rigorous and approximate.

Trayer, George W; March, H W

1930-01-01

416

Bending-torsion flutter calculations modified by subsonic compressibility corrections  

NASA Technical Reports Server (NTRS)

A number of calculations of bending-torsion wing flutter are made at two Mach numbers, m=0 (incompressible case) and m=0.7, and results are compared. The air forces employed for the case of m=0.7 are based on Frazer's recalculation of Possio's results, which are derived on the assumption of small disturbances to the main flow. For ordinary wings of normal density and of low bending frequency in comparison with torsion frequency, the compressibility correction to the flutter speed appears to be of the order of a few percent; whereas the correction to flutter speed for high-density wing sections, such as propeller sections, and to the wing-divergence speed in general, may be based on a rule using the (1 - m(2))1/4 factor and, for m=0.7, represents a decrease of the order of 17 percent.

Garrick, I E

1946-01-01

417

Structural plasticity of single chromatin fibers revealed by torsional manipulation  

E-print Network

Magnetic tweezers are used to study the mechanical response under torsion of single nucleosome arrays reconstituted on tandem repeats of 5S positioning sequences. Regular arrays are extremely resilient and can reversibly accommodate a large amount of supercoiling without much change in length. This behavior is quantitatively described by a molecular model of the chromatin 3-D architecture. In this model, we assume the existence of a dynamic equilibrium between three conformations of the nucleosome, which are determined by the crossing status of the entry/exit DNAs (positive, null or negative). Torsional strain, in displacing that equilibrium, extensively reorganizes the fiber architecture. The model explains a number of long-standing topological questions regarding DNA in chromatin, and may provide the ground to better understand the dynamic binding of most chromatin-associated proteins.

Aurelien Bancaud; Natalia Conde e Silva; Maria Barbi; Gaudeline Wagner; Jean-Francois Allemand; Julien Mozziconacci; Christophe Lavelle; Vincent Croquette; Jean-Marc Victor; Ariel Prunell; Jean-Louis Viovy

2007-07-13

418

Electrostatic micro torsion mirrors for an optical switch matrix  

Microsoft Academic Search

We have developed a new type of compact optical switch using silicon micromachining technique. Torsion mirrors (300 ?m×600 ?m) supported by thin polysilicon beams (16 ?m wide, 320 ?m long, and 0.4 ?m thick) are arranged in a 2×2 matrix (total size 3 mm×5 mm, t 0.3 mm). The mirrors are independently attracted by electrostatic force of applied bias voltage

Hiroshi Toshiyoshi; Hiroyuki Fujita

1996-01-01

419

Observation of 1990 solar eclipse by a torsion pendulum  

SciTech Connect

During the solar eclipse of 22 July 1990 in the city of Bielomorsk of the U.S.S.R., we repeated the torsion pendulum experiment of Saxl and Allen, who reported an anomalous period increase during the solar eclipse of 7 March 1970. The relative change in the pendulum's period associated with the eclipse was found to be less than 5.2{times}10{sup {minus}5} (90% confidence).

Luo Jun; Li Jianguo; Zhang Xuerong (Huazhong University of Science and Technology, Wuhan (China)); Liakhovets, V. (Patrice Lumumba Peoples Friendship University, Moscow (U.S.S.R.)); Lomonosov, M.; Ragyn, A. (Krasnopresnenskaya Observatory, Sternberg Astronomical Institute, Moscow (U.S.S.R.))

1991-10-15

420

Genetic and clinical features of primary torsion dystonia  

PubMed Central

Primary torsion dystonia (PTD) is defined as a syndrome in which dystonia is the only clinical sign (except for tremor), and there is no evidence of neuronal degeneration or an acquired cause by history or routine laboratory assessment. Seven different loci have been recognized for PTD but only two of the genes have been identified. In this review we will described the phenotypes associated with these loci and discuss the responsible gene. PMID:21168499

Ozelius, Laurie J.; Bressman, Susan B.

2011-01-01

421

Modeling of an electrostatic torsional micromirror for laser projection system  

Microsoft Academic Search

This paper presents the Simulink model of a new 2D torsional scanning micromirror. This micro-opto-electro-mechanical-system\\u000a (MOEMS) is very important towards the integration into a system on a package of a complete laser projection system. Modeling\\u000a and simulation of the MOEMS is a key point for the development of the proper micromirror electronic conditioning interface\\u000a thus reducing time to market and

Eleonora Marchetti; Emilio Volpi; Francesco Battini; Luca Bacciarelli; Luca Fanucci; Ulrich Hofmann

2010-01-01

422

Residual strain evolution in steel samples: tension versus torsion  

Microsoft Academic Search

Torsion provides a unique opportunity to probe mechanical behavior of materials subjected to pure state of shear stress. In\\u000a this research, identical steel alloy (12L14) hollow cylinder samples are subjected to predetermined amounts of plastic axial\\u000a and shear strain such that their octahedral shear strain (an invariant) are identical for comparison. Measurements were made\\u000a at the residual stress measuring facility

J. R. Bunn; Dayakar Penumadu; Camden R Hubbard

2010-01-01

423

Calibration of combined bending-torsion fatigue reliability data reduction  

NASA Technical Reports Server (NTRS)

The combined bending-torsion fatigue reliability research machines are described. Three such machines are presently in operation. The calibration of these machines is presented in depth. Fatigue data generated with these machines for SAE 4340 steel grooved specimens subjected to reversed bending and steady torque loading are given. The data reduction procedure is presented. Finally, some comments are made about notch sensitivity and stress concentration as applied to combined fatigue.

Kececioglu, D.; Mcconnell, J. B.

1969-01-01

424

Torsion-balance tests of the weak equivalence principle  

E-print Network

We briefly summarize motivations for testing the weak equivalence principle and then review recent torsion-balance results that compare the differential accelerations of beryllium-aluminum and beryllium-titanium test body pairs with precisions at the part in $10^{13}$ level. We discuss some implications of these results for the gravitational properties of antimatter and dark matter, and speculate about the prospects for further improvements in experimental sensitivity.

T. A. Wagner; S. Schlamminger; J. H. Gundlach; E. G. Adelberger

2012-07-10

425

Simple currents versus orbifolds with discrete torsion - a complete classification  

Microsoft Academic Search

We give a complete classification of all simple current modular invariants, extending previous results for (Zp)k to arbitrary centers. We obtain a simple explicit formula for the most general case. Using orbifold techniques to this end, we find a one-to-one correspondence between simple current invariants and subgroups of the center with discrete torsions. As a by-product, we prove the conjectured

M. Kreuzer; A. N. Schellekens

1994-01-01

426

Compressive and torsional behaviour of Kevlar 49 fibre  

Microsoft Academic Search

The mechanical anisotropy of an aromatic polyamide fibre, Kevlar 49, was studied in tension, compression and torsion. A new\\u000a technique involved applying small and defined compressive strains to filaments by bonding them to one side of a beam which\\u000a is subsequently bent to compress the fibres. Using scanning electron and optical microscopy, fibres were shown to form regularly-spaced\\u000a helical kink

S. J. Deteresa; S. R. Allen; R. J. Farris; R. S. Porter

1984-01-01

427

The initial torsional stiffness of shells with interior webs  

NASA Technical Reports Server (NTRS)

A method of calculating the stresses and torsional stiffness of thin shells with interior webs is summarized. Comparisons between experimental and calculated results are given for 3 duralumin beams, 5 stainless steel beams and 2 duralumin wings. It is concluded that if the theoretical stiffness is multiplied by a correction factor of 0.9, experimental values may be expected to check calculated values within about 10 percent.

Kuhn, Paul

1935-01-01

428

Laterally actuated torsional micromirrors for large static deflection  

Microsoft Academic Search

We report on the implementation of laterally electrostatically actuated, torsionally suspended silicon-on-insulator (SOI) micromirrors with a static optical deflection angle of over 40° peak-to-peak. Decoupling the actuator and mirror design allows for large actuator arrays, allowing large dc deflection angle and high resonant frequency to coexist in the same device. The micromirror structures are fully monolithic, micromachined from the front

Veljko Milanovic; M. Last; K. S. J. Pister

2003-01-01

429

Composite box beam analysis - Theory and experiments  

NASA Technical Reports Server (NTRS)

Beam theory is widely used as a first approximation in numerous structural applications. When applied to composite beams, the accuracy of beam theory becomes questionable because (1) the shearing and warping deformations become significant, as the shearing stiffness of composite laminates is often very low, and (2) several elastic couplings can occur that strongly influence the behavior of composite beams. The torsional behavior of thin-walled composite beams has important implications for aeronautical structures and is deeply modified by the above nonclassical effects. This paper presents two comprehensive analysis methodologies for composite beams and describes experimental results obtained from a thin-walled, rectangular cross-sectional beam. The theoretical predictions are found in good agreement with the observed twist and strain distributions. Out-of-plane torsional warping of the cross-section is found to be the key factor for an accurate modeling of the torsional behavior of such structures.

Bauchau, O. A.; Coffenberry, B. S.; Rehfield, L. W.

1987-01-01

430

R+S^2 theories of gravity without big-bang singularity  

E-print Network

The R+S^2 theories of gravity with the matter fields described by a Weyssenhoff fluid are analyzed, where S^2 stands for the quadratic torsion terms. It is found that a subclass of the R+S^2 theories may solve the singularity problem of the homogenous and isotropic universe. Actually, it is shown that the torsion effect is either zero or equivalent to an additional ideal fluid with the energy density equal to the hydrostatic pressure.

Lu, Jia-An

2014-01-01

431

Friction and shear fracture of an adhesive contact under torsion.  

PubMed

The shear failure or stiction of an adhesive contact between a poly(dimethylsiloxane) (PDMS) rubber and a glass lens has been investigated using a torsional contact configuration. As compared to linear sliding, torsion presents the advantage of inducing a shear failure under a pure mode III condition, while preserving the cylindrical symmetry of the contact. The surface of the transparent PDMS substrate was marked using a network of dots in order to monitor continuously the in-plane surface displacements during the stiction process. Using a previously developed inversion procedure (A. Chateauminois and C. Fretigny, Eur. Phys. J. E 27, 221 (2008)), the corresponding surface shear stress distributions were obtained from the displacement fields. Stiction was found to involve the progressive shrinkage of a central adhesive zone surrounded by an annular microslip region. Adhesion effects were especially evidenced from a stress overshoot at the boundary of the adhesive zone. The experimental data were analysis using an extension to torsional contact of the Maugis-Dugdale approach's to adhesive contacts which takes into account frictional effects. This model allowed to extract an effective adhesion energy in the presence of friction, which dependence on kinetics effect is briefly discussed. PMID:20365630

Chateauminois, Antoine; Fretigny, Christian; Olanier, Ludovic

2010-02-01

432

Optical diagnosis of testicular torsion: feasibility and methodology  

NASA Astrophysics Data System (ADS)

Background: Torsion of the testis compromises blood flow through the spermatic cord; testicular ischemia results which if not diagnosed promptly and corrected surgically irrevocably damages the testis. Current diagnostic modalities aimed at rationalizing surgical exploration by demonstrating interruption of spermatic cord blood flow or testicular ischemia have limited applicability. Near infrared spectroscopy (NIRS) offers a non-invasive optical method for detection of ischemia; continuous wave and frequency domain devices have been used experimentally; no device customized for clinical use has been designed. Methods: A miniature spatially resolved NIRS device with light emitting diode light source was applied over the right and left spermatic cord and the difference in oxygen saturation between the two sides measured. Results: In a 14-month old boy with a history of unilateral testicular pain color Doppler ultrasonography was equivocal but the NIRS-derived tissue oxygen saturation index (TSI) was significantly reduced on the left side. Confirmation of torsion of the left testicle was made surgically. Conclusions: Spatially resolved NIRS monitoring of spermatic cord oxygen saturation is feasible in children, adding to prior studies of testicular oxygen saturation in adults. Customized device design and further clinical trials would enhance the applicability of NIRS as a diagnostic entity for torsion.

Shadgan, Babak; Macnab, Andrew; Stothers, Lynn; Kajbafzadeh, A. M.

2014-03-01

433

Effects of High-Frequency Torsional Impacts on Rock Drilling  

NASA Astrophysics Data System (ADS)

High-frequency torsional impact drilling (HFTID) is a new technology which provides stable and efficient drilling. The goal of the present study is to investigate the effects of high-frequency torsional impacts on rock drilling. The impact parameters of the high-frequency torsional impact generator (HFTIG) are obtained by conducting a series of laboratory tests. The results of the tests reveal that the impact time decreases and the impact force increases with increasing impact frequency. The parameters are used as input for simulations of the rock crushing process, and a series of models for investigating the respective performance of HFTID and conventional drilling are developed. In addition, the Drucker-Prager criterion is used to describe the constitutive laws of the rock element, and the equivalent plastic strain criterion is adopted as the damage criterion. The models are run to simulate the dynamic rock crushing processes. The results of the simulations show that increase of the impact frequency results in a significant improvement in the rate of penetration (ROP), and a decrease in the life of the HFTIG. Considering the tool life and ROP, the optimum impact frequency of the HFTIG is 15 Hz. Finally, the performance of the HFTID technique is evaluated.

Zhu, Xiaohua; Tang, Liping; Tong, Hua

2014-07-01

434

Torsional sensing of small-molecule binding using magnetic tweezers  

PubMed Central

DNA-binding small molecules are widespread in the cell and heavily used in biological applications. Here, we use magnetic tweezers, which control the force and torque applied to single DNAs, to study three small molecules: ethidium bromide (EtBr), a well-known intercalator; netropsin, a minor-groove binding anti-microbial drug; and topotecan, a clinically used anti-tumor drug. In the low-force limit in which biologically relevant torques can be accessed (<10?pN), we show that ethidium intercalation lengthens DNA ?1.5-fold and decreases the persistence length, from which we extract binding constants. Using our control of supercoiling, we measure the decrease in DNA twist per intercalation to be 27.3?±?1° and demonstrate that ethidium binding delays the accumulation of torsional stress in DNA, likely via direct reduction of the torsional modulus and torque-dependent binding. Furthermore, we observe that EtBr stabilizes the DNA duplex in regimes where bare DNA undergoes structural transitions. In contrast, minor groove binding by netropsin affects neither the contour nor persistence length significantly, yet increases the twist per base of DNA. Finally, we show that topotecan binding has consequences similar to those of EtBr, providing evidence for an intercalative binding mode. These insights into the torsional consequences of ligand binding can help elucidate the effects of small-molecule drugs in the cellular environment. PMID:20624816

Lipfert, Jan; Klijnhout, Sven; Dekker, Nynke H.

2010-01-01

435

A torsion balance search for spin-coupled forces  

NASA Astrophysics Data System (ADS)

Interactions that involve the coupling of a particle's intrinsic spin independent of its magnetic moment have been postulated, but never detected. This dissertation describes a precision search for spin-coupled forces that arise in the context of broken Lorentz and CPT symmetries, exotic particle exchange, non-commutative geometries, and torsion gravity. We used a torsion pendulum containing 9.8 x 1022 polarized electron spins to search for interactions between the pendulum's electrons and a vector field fixed in inertial space, a condensate of exotic particles defining a preferred frame in the universe, unpolarized matter in the laboratory's environment and the sun, and polarized matter in spin sources placed near to the pendulum. We have seen no evidence for these spin-coupled interactions. The measurements reported here constrain the energy required to flip an electron spin about directions fixed in inertial space to be ? 10-22 eV. We have used these constraints to place limits on preferred-frame effects and exotic boson exchange that are up to four orders of magnitude lower than the previous reported limits, and we present the first limits on dynamical effects associated with broken Lorentz symmetry. This dissertation describes the torsion balance apparatus used to perform these measurements, as well as the analysis of experimental data and systematic effects, and the corresponding results.

Cramer, Claire E.

436

Friction and shear fracture of an adhesive contact under torsion  

NASA Astrophysics Data System (ADS)

The shear failure or stiction of an adhesive contact between a poly(dimethylsiloxane) (PDMS) rubber and a glass lens has been investigated using a torsional contact configuration. As compared to linear sliding, torsion presents the advantage of inducing a shear failure under a pure mode III condition, while preserving the cylindrical symmetry of the contact. The surface of the transparent PDMS substrate was marked using a network of dots in order to monitor continuously the in-plane surface displacements during the stiction process. Using a previously developed inversion procedure (A. Chateauminois and C. Fretigny, Eur. Phys. J. E 27, 221 (2008)), the corresponding surface shear stress distributions were obtained from the displacement fields. Stiction was found to involve the progressive shrinkage of a central adhesive zone surrounded by an annular microslip region. Adhesion effects were especially evidenced from a stress overshoot at the boundary of the adhesive zone. The experimental data were analysis using an extension to torsional contact of the Maugis-Dugdale approach’s to adhesive contacts which takes into account frictional effects. This model allowed to extract an effective adhesion energy in the presence of friction, which dependence on kinetics effect is briefly discussed.

Chateauminois, Antoine; Fretigny, Christian; Olanier, Ludovic

2010-02-01

437

Development of a torsion balance for adhesion measurements  

NASA Technical Reports Server (NTRS)

A new torsion balance for study of adhesion in ceramics is discussed. A torsion wire and a linear variable differential transformer are used to monitor load and to measure pull-off force (adhesion force). The investigation suggests that this torsion balance is valuable in studying the interfacial properties of ceramics in controlled environments such as in ultrahigh vacuum. The pull-off forces measured in dry, moist, and saturated nitrogen atmosphere demonstrate that the adhesion of silicon nitride contacts remains low at humidities below 80 percent but rises rapidly above that. The adhesion at saturation is 10 times or more greater than that below 80 percent relative humidity. The adhesion in a saturated atmosphere arises primarily from the surface tension effects of a thin film of water adsorbed on the surface. The surface tension of the water film was 58 x 10 to the minus 5 to 65 x 10 to the minus 5 power. The accepted value for water is 72.7 x 10 to the minus 5 power N/cm. Adhesion characteristics of silicon nitride in contact with metals, like the friction characteristics of silicon carbide to metal contacts, can be related to the relative chemical activity of metals in ultrahigh vacuum. The more active the metal, the higher the adhesion.

Miyoshi, Kazuhisa; Maeda, Chikayoshi; Masuo, Ryuichi

1988-01-01

438

A Rare Emergency: Testicular Torsion in the Inguinal Canal  

PubMed Central

Objectives. To report our experience and present the largest series of testicular torsion cases in the inguinal canal. Material and Methods. The clinical data of 13 patients with testicular torsion in the inguinal canal treated between 2005 and 2013 were reviewed. Recorded patient age, whether the testes were palpable or not, side of the affected testes, the presence of hernia, ischemia time, and operation outcomes were assessed. Results. Patient age ranged from 8 to 70 months (29.15 ± 20.22). Mean ischemia time was 16.5 ± 21.3 hours. Accompanying inguinal hernia was present in 92% of the cases (12/13). Four of the thirteen patients (30.8%) were treated by orchiectomy because the necrosis was present after prolonged ischemia time. Nine patients (69.2%) were treated by single session orchidopexy. Conclusion. Torsion of testes in the inguinal canal is a rare disease, but with rapid diagnosis, affected testes can be salvaged, but the key factor is to keep this condition in mind.

?ener, Nevzat Can; Bas, Okan; Yesil, Suleyman; Zengin, Kursad; Imamoglu, Abdurrahim

2015-01-01

439

Continuous Theta Burst Stimulation of Angular Gyrus Reduces Subjective Recollection  

PubMed Central

The contribution of lateral parietal regions such as the angular gyrus to human episodic memory has been the subject of much debate following widespread observations of left parietal activity in healthy volunteers during functional neuroimaging studies of memory retrieval. Patients with lateral parietal lesions are not amnesic, but recent evidence indicates that their memory abilities may not be entirely preserved. Whereas recollection appears intact when objective measures such as source accuracy are used, patients often exhibit reduced subjective confidence in their accurate recollections. When asked to recall autobiographical memories, they may produce spontaneous narratives that lack richness and specificity, but can remember specific details when prompted. Two distinct theoretical accounts have been proposed to explain these results: that the patients have a deficit in the bottom-up capturing of attention by retrieval output, or that they have an impairment in the subjective experience of recollection. The present study aimed to differentiate between these accounts using continuous theta burst stimulation (cTBS) in healthy participants to disrupt function of specific left parietal subregions, including angular gyrus. Inconsistent with predictions of the attentional theory, angular gyrus cTBS did not result in greater impairment of free recall than cued recall. Supporting predictions of the subjective recollection account, temporary disruption of angular gyrus was associated with highly accurate source recollection accuracy but a selective reduction in participants’ rated source confidence. The findings are consistent with a role for angular gyrus in the integration of memory features into a conscious representation that enables the subjective experience of remembering. PMID:25333985

Yazar, Yasemin; Bergström, Zara M.; Simons, Jon S.

2014-01-01

440

Supersonic jet fluorescence spectra of 4-methylstyrene: Ground state vibration wavenumbers and improved torsional potential functions  

NASA Astrophysics Data System (ADS)

Single vibronic level (dispersed) fluorescence spectra of 4-methylstyrene, with excitation in various excited vibrational levels of S1, have provided wavenumbers of some a' and a? vibrations in S0 and energy levels for the C(1)-C(?) vinyl torsional and the methyl torsional vibrations. The estimated values of the parameters for the torsional potentials are V ?2= 943±58 cm -1, V ?4= -208±31 cm -1, for vinyl torsion in S0; V ?3= 28±4 cm -1, V ?6= -7±1 cm -1, for methyl torsion in S0; and V ?3= -8±4 cm -1, V ?6= -19±4 cm -1, for methyl torsion in S1. The vinyl group is coplanar with the benzene ring in S0. The methyl group is eclipsed, relative to the benzene ring, in S0, but almost staggered in S1.

Hollas, J. Michael; Taday, Philip F.; Gordon, Robert D.

1992-05-01

441

Improving the sensitivity of a torsion pendulum by using an optical spring method  

SciTech Connect

We present a scheme aiming at improving the sensitivity of a torsion pendulum by means of radiation-pressure-induced optical spring. Two partial-reflective mirrors are installed on the opposite sides of a torsion pendulum, and one high-reflective mirror is mounted at the end of the torsion beam so that two identical Fabry-Perot cavities can be formed and aligned in series. Due to the antisymmetric radiation pressures acting on the opposite sides of the torsion beam, a negative restoring coefficient can be generated within a certain dynamic range, such that both the resultant torsional rigidity and the resonant frequency of the torsion pendulum are reduced, and the minimum detectable response torque in high-frequency region can be reduced accordingly.

Wang Qinglan; Yeh Hsienchi; Zhou Zebing; Luo Jun [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2009-10-15

442

Angular Power Spectrum in Modular Invariant Inflation Model  

SciTech Connect

A scalar potential of inflation is proposed and the angular power spectra of the adiabatic density perturbations are computed. The potential consists of three scalar fields, S, Y and T, together with two free parameters. By fitting the parameters to cosmological data at the fixed point T = 1, we find that the potential behaves like the single-field potential of S, which slowly rolls down. We further show that the inflation predictions corresponding to this potential provide a good fit to the recent three-year WMAP data, e.g. the spectral index n{sub s} = 0.951.The TT and TE angular power spectra obtained from our model almost completely coincide with the corresponding results obtained from the {lambda}CDM model. We conclude that our model is considered to be an adequate theory of inflation that explains the present data.

Hayashi, Mitsuo J.; Okame, Y.; Takagi, K.; Watanabe, T. [Department of Physics, Tokai University, 1117 Kitakaname, Hiratsuka, 259-1292 (Japan); Hirai, S.; Takami, T. [Department of Digital Games, Osaka Electro-Communication University, 1130-70 Kiyotaki, Shijonawate, Osaka, 575-0063 (Japan)

2008-05-29

443

Minimum uncertainty measurements of angle and angular momentum.  

PubMed

We present an accurate description of the conjugate pair angle-angular momentum in terms of the exponential of the angle instead of the angle itself, which leads to dispersion as a natural measure of resolution. Intelligent states minimizing the uncertainty product under the constraint of a given uncertainty in angle or in angular momentum turn out to be given by Mathieu wave functions. We discuss Gaussian approximations to these optimal states in terms of von Mises distributions. The theory is successfully applied to the spatial degrees of freedom of a photon and verified in an experiment that employs computer-controlled spatial light modulators at both the state preparation and the analyzing stages. PMID:17280283

Hradil, Z; Rehácek, J; Bouchal, Z; Celechovský, R; Sánchez-Soto, L L

2006-12-15

444

The effect of sterilization on bending and torsional properties of K-files manufactured with different metallic alloys.  

PubMed

The purpose of this study was to assess the effect of dry-heat or autoclave sterilization on the resistance to fracture in torque and angular deflection and the resistance to bending of K-type files made of nickel-titanium (Nitiflex, Naviflex), titanium (Microtitane) or stainless steel (Flexofile, Flex-R). Ten K-type files of each sort, from size 25 to 40, were tested, according to ANSI/ADA specification 28 (1988) and ISO specification 3630 (1992). Sterilization with dry heat and autoclave slightly decreased the flexibility of files made of stainless steel and nickel-titanium for most of the sizes, although the values obtained satisfied ISO specifications. The files made of titanium showed an increased flexibility after sterilization with autoclave (sizes 30 and 35) and dry heat (sizes 30, 35 and 40). Resistance to fracture varied amongst the five groups of files tested as follows: it decreased in some sizes of stainless-steel instruments, decreased in all sizes of titanium files assessed by the torsional moment, and either increased or decreased in some sizes of nickel-titanium files. All files tested, however, satisfied relevant standards for angular deflection after being subjected to sterilization with an autoclave or dry heat. PMID:9823128

Canalda-Sahli, C; Brau-Aguadé, E; Sentís-Vilalta, J

1998-01-01

445

Theory, Theory  

NSDL National Science Digital Library

This lesson includes a theory-evaluation activity. A set of five scenarios (theories for how diverse life came into existence on Earth) is divided evenly throughout the class, so each student is asked to evaluate one theory. Students then come together in groups of five, so that all theories are represented in each group, where they are compared and evaluated. Each group reports to the entire class for further discussion and clarifications.

Kimmel, Michael

446

Fast torsional waves and strong magnetic field within the Earth’s core  

NASA Astrophysics Data System (ADS)

The magnetic field inside the Earth's fluid and electrically conducting outer core cannot be directly probed. The root-mean-squared (r.m.s.) intensity for the resolved part of the radial magnetic field at the core-mantle boundary is 0.3mT, but further assumptions are needed to infer the strength of the field inside the core. Recent diagnostics obtained from numerical geodynamo models indicate that the magnitude of the dipole field at the surface of a fluid dynamo is about ten times weaker than the r.m.s. field strength in its interior, which would yield an intensity of the order of several millitesla within the Earth's core. However, a 60-year signal found in the variation in the length of day has long been associated with magneto-hydrodynamic torsional waves carried by a much weaker internal field. According to these studies, the r.m.s. strength of the field in the cylindrical radial direction (calculated for all length scales) is only 0.2mT, a figure even smaller than the r.m.s. strength of the large-scale (spherical harmonic degree n<=13) field visible at the core-mantle boundary. Here we reconcile numerical geodynamo models with studies of geostrophic motions in the Earth's core that rely on geomagnetic data. From an ensemble inversion of core flow models, we find a torsional wave recurring every six years, the angular momentum of which accounts well for both the phase and the amplitude of the six-year signal for change in length of day detected over the second half of the twentieth century. It takes about four years for the wave to propagate throughout the fluid outer core, and this travel time translates into a slowness for Alfvén waves that corresponds to a r.m.s. field strength in the cylindrical radial direction of approximately 2mT. Assuming isotropy, this yields a r.m.s. field strength of 4mT inside the Earth's core.

Gillet, Nicolas; Jault, Dominique; Canet, Elisabeth; Fournier, Alexandre

2010-05-01

447

A study of structural analysis and dynamic characteristics of a sleeve spring torsional vibration damper  

Microsoft Academic Search

In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore,\\u000a it is necessary to establish preventive measures to diminish the torsional vibration. A sleeve spring damper is one such measure\\u000a to reduce the torsional vibration. In this study, the closed form equations to predict the spring constant of a sleeve spring

Beom Cheol Hwang; Chung Hwan Jeon; Won Byong Bae; Chul Kim

2010-01-01

448

Process analysis and test of manufacturing of sleeve spring-type torsional vibration damper  

Microsoft Academic Search

In diesel engines, engine torque fluctuation inevitably produces torsional vibration. A sleeve spring-type damper commonly\\u000a is used to reduce this vibration. In this paper, closed form equations to predict the spring constant of a sleeve spring and\\u000a the torsional characteristics of a torsional vibration damper are proposed for calculation of the stiffness of the damper.\\u000a The equations were verified through

Beom Cheol Hwang; Won Byong Bae; Chul Kim

2010-01-01

449

Ptolemy diagrams and torsion pairs in the cluster category of Dynkin type A_n  

E-print Network

We give a complete classification of torsion pairs in the cluster category of Dynkin type A_n. Along the way we give a new combinatorial description of Ptolemy diagrams, an infinite version of which was introduced by Ng. This allows us to count the number of torsion pairs in the cluster category of type A_n. We also count torsion pairs up to Auslander-Reiten translation.

Holm, Thorsten; Rubey, Martin

2010-01-01

450

Abnormal Elevated CA 19-9 in the Dermoid Cyst: A Sign of the Ovarian Torsion?  

PubMed Central

Dermoid cyst is the most common germ cell tumor of the ovary containing various tissue elements. Ovarian torsion is a common complication of which ultrasonographic diagnosis is confusing. We report here a 14-year-old adolescent with painless torsion of the ovary including dermoid cyst and with abnormal elevated CA 19-9 serum levels. Elevated CA 19-9 level may be related to ovarian torsion and may predict the extent of tissue necrosis. PMID:23840991

Goker, Asli; Pala, Halil Gursoy; Ordu, Sercin

2013-01-01

451

3D Curves With a Prescribed Curvature and Torsion for a Flying Robot  

SciTech Connect

The objective of this paper is to generate a desired flight path to be followed by an flying robot. A curve with discontinuous curvature and torsion is not appropriate for smooth motions for any vehicle architecture. Three different classes of curves are presented. First, constant curvature and torsion followed by a linear variation versus the curvilinear abscissa then a quadratic variation. Finally, the problem of maneuvers between two trim helices of different curvature and torsion is tackled with.

Bestaoui, Yasmina [Informatics, Integrative Biology and Complex Systems, University of Evry 40 Rue de Pelvoux, 91020 Evry Cedex (France)

2008-06-12

452

Free-space fiber-optic switches based on MEMS vertical torsion mirrors  

Microsoft Academic Search

This paper reports on the design, fabrication, and performance of a novel MEMS (micro-electro-mechanical-system) fiber-optic switch based on surface-micromachined vertical torsion mirrors. The vertical torsion mirror itself can be used as a 1×2 or an ON-OFF switch. A 2×2 MEMS fiber-optic switch with four vertical torsion mirrors has also been fabricated. The switching voltage is measured to be 80 V

Shi-Sheng Lee; Long-Sun Huang; Chang-Jin Kim; Ming C. Wu

1999-01-01

453

Torsion Tests of 24S-T Aluminum-alloy Noncircular Bar and Tubing  

NASA Technical Reports Server (NTRS)

Tests of 24S-T aluminum alloy have been made to determine the yield and ultimate strengths in torsion of noncircular bar and tubing. An approximate basis for predicting these torsional strength characteristics has been indicated. The results show that the torsional stiffness and maximum shearing stresses within the elastic range may be computed quite closely by means of existing formulas based on mathematical analysis and the membrane analogy.

Moore, R L; Paul, D A

1943-01-01

454

Application of a boundary element method to the study of dynamical torsion of beams  

NASA Technical Reports Server (NTRS)

During dynamic torsion of beam elements, consideration of nonuniform warping effects involves a more general technical formulation then that of Saint-Venant. Nonclassical torsion constants appear in addition to the well known torsional rigidity. The adaptation of the boundary integral element method to the calculation of these constants for general section shapes is described. The suitability of the formulation is investigated with some examples of thick as well as thin walled cross sections.

Czekajski, C.; Laroze, S.; Gay, D.

1982-01-01

455

Extended torsional tests of an interlocked bi-stem satellite boom  

NASA Technical Reports Server (NTRS)

The effect is reported of continued oscillations of a 1.27-cm interlocked bi-stem satellite boom. The test setup oscillated a boom continuously between set torque limits and periodically recorded its hysteresis characteristics. Results showed that repeated oscillations affected torsional characteristics and that torsional rigidity changed as a function of the number of cycles oscillated within certain torque limits. Torsional characteristics changes caused by repeated oscillations were retained.

Abercrombie, R. A.

1973-01-01

456

Torsion dependence of the covariant Taylor expansion in Riemann-Cartan space  

NASA Astrophysics Data System (ADS)

We clarify the dependence on the torsion tensor of all coefficients in the covariant Taylor expansion of the HMDS coefficient in the heat kernel for the fermion of spin 0264-9381/16/4/027/img1 in Riemann-Cartan space. The dependence on the torsion tensor of the quantities in the expansion coefficients is determined by the 0264-9381/16/4/027/img2 matrices in the quantities, except for that of the matrix potential X itself. The quantities with 0264-9381/16/4/027/img2 matrices contain the torsion tensor only in a peculiar form, and the others are independent of the torsion tensor.

Yajima, S.; Higasida, Y.; Kawano, K.; Kubota, S.-I.

1999-04-01

457

An induction motor model for high-frequency torsional vibration analysis  

NASA Astrophysics Data System (ADS)

High-frequency torsional oscillations of a 50 horsepower (hp) induction motor are investigated up to approximately 30 kHz. It is experimentally determined that torsional oscillations, due to the switching harmonics of the motor drive, contribute significantly to the torsional oscillation of the output shaft. Two torsional vibration models are developed. One model assumes the rotor to be rigid, while the other has a compliant rotor. The compliant model allows for greater transmission of high-frequency oscillations, and a better prediction of the measured output shaft vibration.

Widdle, R. D.; Krousgrill, C. M.; Sudhoff, S. D.

2006-03-01

458

Stability of elastic bending and torsion of uniform cantilever rotor blades in hover with variable structural coupling  

NASA Technical Reports Server (NTRS)

The stability of elastic flap bending, lead-lag bending, and torsion of uniform, untwisted, cantilever rotor blades without chordwise offsets between the elastic, mass, tension, and areodynamic center axes is investigated for the hovering flight condition. The equations of motion are obtained by simplifying the general, nonlinear, partial differential equations of motion of an elastic rotating cantilever blade. The equations are adapted for a linearized stability analysis in the hovering flight condition by prescribing aerodynamic forces, applying Galerkin's method, and linearizing the resulting ordinary differential equations about the equilibrium operating condition. The aerodynamic forces are obtained from strip theory based on a quasi-steady approximation of two-dimensional unsteady airfoil theory. Six coupled mode shapes, calculated from free vibration about the equilibrium operating condition, are used in the linearized stability analysis. The study emphasizes the effects of two types of structural coupling that strongly influence the stability of hingeless rotor blades. The first structural coupling is the linear coupling between flap and lead-lag bending of the rotor blade. The second structural coupling is a nonlinear coupling between flap bending, lead-lag bending, and torsion deflections. Results are obtained for a wide variety of hingeless rotor configurations and operating conditions in order to provide a reasonably complete picture of hingeless rotor blade stability characteristics.

Hodges, D. H., Roberta.

1976-01-01

459

Generalized Poincare algebras and Lovelock-Cartan gravity theory  

E-print Network

We show that the Lagrangian for Lovelock-Cartan gravity theory can be re-formulated as an action which leads to General Relativity in a certain limit. In odd dimensions the Lagrangian leads to a Chern-Simons theory invariant under the generalized Poincar\\'{e} algebra $\\mathfrak{B}_{2n+1},$ while in even dimensions the Lagrangian leads to a Born-Infeld theory invariant under a subalgebra of the $\\mathfrak{B}_{2n+1}$ algebra. It is also shown that torsion may occur explicitly in the Lagrangian leading to new torsional Lagrangians, which are related to the Chern-Pontryagin character for the $B_{2n+1}$ group.

P. K. Concha; D. M. Peñafiel; E. K. Rodríguez; P. Salgado

2015-01-21

460

Angular-Rate Estimation Using Quaternion Measurements  

NASA Technical Reports Server (NTRS)

In most spacecraft (SC) there is a need to know the SC angular rate. Precise angular rate is required for attitude determination, and a coarse rate is needed for attitude control damping. Classically, angular rate information is obtained from gyro measurements. These days, there is a tendency to build smaller, lighter and cheaper SC, therefore the inclination now is to do away with gyros and use other means and methods to determine the angular rate. The latter is also needed even in gyro equipped satellites when performing high rate maneuvers whose angular-rate is out of range of the on board gyros or in case of gyro failure. There are several ways to obtain the angular rate in a gyro-less SC. When the attitude is known, one can differentiate the attitude in whatever parameters it is given and use the kinematics equation that connects the derivative of the attitude with the satellite angular-rate and compute the latter. Since SC usually utilize vector measurements for attitude determination, the differentiation of the attitude introduces a considerable noise component in the computed angular-rate vector.

Azor, Ruth; Bar-Itzhack, Y.; Deutschmann, Julie K.; Harman, Richard R.

1998-01-01

461

Jet angular momentum and quantum chromodynamics  

Microsoft Academic Search

We discuss several observable properties of hadronic final states in electron-positron annihilation that bear on the angular momentum content of jets. In particular we calculate in perturbative quantum chromodynamics the jet oblateness and the jet axis angular distribution as a function of jet invariant mass. We also consider QCD information on the PT correlation in opposite jets.

L. Clavelli

1980-01-01

462

Dijet angular distributions at D0  

SciTech Connect

Measurements of the dijet angular distributions are relatively insensitive to parton distribution functions and thus offer an excellent method of testing the LO and NLO predictions of perturbative QCD. The authors present measurements of the dijet angular distributions for {vert_bar}{eta}{vert_bar} < 3.0 in p{anti p} collisions at {radical}s = 1.8 TeV.

Fatyga, M.K. [Univ. of Rochester, NY (United States); D0 Collaboration

1996-09-01

463

The Angular Momentum-Energy Space  

E-print Network

In this paper we shall define and study the angular momentum-energy space for the classical problem of plane-motions of a particle situated in a potential field of a central force. We shall present the angular momentum-energy space for some important cases.

Dan Comanescu

2007-02-09

464

Angular Dependences of Prism Liquid Crystal Polarizer  

Microsoft Academic Search

The angular dependences of extinction ratio and polarization plane orientation for prism liquid crystal polarizers have been measured fix 632. 8nm vawelength in the limits of angular aperture. The planar and homeotropic orientations of nematic liquid crystal layer were used.

A. A. Karetnikov; A. P. Kavshik; Y. I. Rjumtsev

1997-01-01

465

Quartz angular rate sensor for automotive control  

Microsoft Academic Search

A new quartz angular rate sensor has been developed for automotive controls. The principle of the sensor is detection of the Coriolis force with a vibrator An H shape vibrator supported with a stein at the center was used The vibrator supported at the center was good for the isolation of a small motion detecting angular rate from an extremely

Y. Nonomura; M. Fujiyoshi; Y. Omura; K. Tsukada; M. Okuwa; T. Morikawa; N. Sugitani; S. Satou; N. Kurata; S. Matsushige

2001-01-01

466

Angular momentum in the global atmospheric circulation  

Microsoft Academic Search

Angular momentum is a variable of central importance to the dynamics of the atmosphere both regionally and globally. Moreover, the angular momentum equations yield a precise description of the dynamic interaction of the atmosphere with the oceans and the solid Earth via various torques as exerted by friction, pressure against the mountains and the nonspherical shape of the Earth, and

Joseph Egger; Klaus Weickmann; Klaus-Peter Hoinka

2007-01-01

467

The angular momentum of the Oort cloud  

NASA Technical Reports Server (NTRS)

An evaluation is made of the work of Marochnik et al. (1988), which estimated that the angular momentum of the Oort cloud is 2-3 orders of magnitude greater than the planetary system's total angular momentum. It is noted that most of the angular momentum in the currently observed Oort cloud is the result of the effects of external perturbers over the solar system's history, and it is demonstrated that the total current angular momentum is probably in the 6.0 x 10 to the 50th to 1.1 x 10 to the 51st g sq cm/sec range; original angular momentum was probably a factor of 5 below such values.

Weissman, Paul R.

1991-01-01

468

The angular momentum of the Oort cloud  

SciTech Connect

An evaluation is made of the work of Marochnik et al. (1988), which estimated that the angular momentum of the Oort cloud is 2-3 orders of magnitude greater than the planetary system's total angular momentum. It is noted that most of the angular momentum in the currently observed Oort cloud is the result of the effects of external perturbers over the solar system's history, and it is demonstrated that the total current angular momentum is probably in the 6.0 x 10 to the 50th to 1.1 x 10 to the 51st g sq cm/sec range; original angular momentum was probably a factor of 5 below such values. 21 refs.

Weissman, P.R. (JPL, Pasadena, CA (USA))

1991-01-01

469

Quark angular momentum in a spectator model  

E-print Network

We investigate the quark angular momentum in a model with the nucleon being a quark and a spectator. Both scalar and axial-vector spectators are included. We perform the calculations in the light-cone formalism where the parton concept is well defined. We calculate the quark helicity and canonical orbital angular momentum. Then we calculate the gravitational form factors which are often related to the kinetic angular momentums, and find that even in a no gauge field model we cannot identify the canonical angular momentums with half the sum of gravitational form factors. In addition, we examine the model relation between the orbital angular momentum and pretzelosity, and find it is violated in the axial-vector case.

Liu, Tianbo

2015-01-01

470

Vacuum static compactified wormholes in eight-dimensional Lovelock theory  

SciTech Connect

In this paper, new exact solutions in eight-dimensional Lovelock theory will be presented. These solutions are the vacuum static wormhole, the black hole, and generalized Bertotti-Robinson space-times with nontrivial torsion. All of the solutions have a cross product structure of the type M{sub 5}x{sigma}{sub 3}, where M{sub 5} is a five-dimensional manifold and {sigma}{sub 3} a compact constant curvature manifold. The wormhole is the first example of a smooth vacuum static Lovelock wormhole which is neither Chern-Simons nor Born-Infeld. It will be also discussed how the presence of torsion affects the 'navigableness' of the wormhole for scalar and spinning particles. It will be shown that the wormhole with torsion may act as 'geometrical filter': A very large torsion may 'increase the traversability' for scalars while acting as a 'polarizator' on spinning particles. This may have interesting phenomenological consequences.

Canfora, Fabrizio [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Giacomini, Alex [Instituto de Fisica, Facultad de Ciencias, Universidad Austral de Chile, Valdivia (Chile); Centro de Estudios Cientificos (CECS), Valdivia (Chile)

2008-10-15

471

Ocular torsion as a test of the asymmetry hypothesis of space motion sickness  

NASA Astrophysics Data System (ADS)

Disconjugate eye torsion induced by O G and 1.8 G during parabolic flight was studied in nine former astronauts in 1990 and eight in 1991, four of whom were included in the previous experiment. The astronauts could be divided into two statistically significant g