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Sample records for c-s-c-c torsion angles

  1. Deep learning methods for protein torsion angle prediction.

    Science.gov (United States)

    Li, Haiou; Hou, Jie; Adhikari, Badri; Lyu, Qiang; Cheng, Jianlin

    2017-09-18

    Deep learning is one of the most powerful machine learning methods that has achieved the state-of-the-art performance in many domains. Since deep learning was introduced to the field of bioinformatics in 2012, it has achieved success in a number of areas such as protein residue-residue contact prediction, secondary structure prediction, and fold recognition. In this work, we developed deep learning methods to improve the prediction of torsion (dihedral) angles of proteins. We design four different deep learning architectures to predict protein torsion angles. The architectures including deep neural network (DNN) and deep restricted Boltzmann machine (DRBN), deep recurrent neural network (DRNN) and deep recurrent restricted Boltzmann machine (DReRBM) since the protein torsion angle prediction is a sequence related problem. In addition to existing protein features, two new features (predicted residue contact number and the error distribution of torsion angles extracted from sequence fragments) are used as input to each of the four deep learning architectures to predict phi and psi angles of protein backbone. The mean absolute error (MAE) of phi and psi angles predicted by DRNN, DReRBM, DRBM and DNN is about 20-21° and 29-30° on an independent dataset. The MAE of phi angle is comparable to the existing methods, but the MAE of psi angle is 29°, 2° lower than the existing methods. On the latest CASP12 targets, our methods also achieved the performance better than or comparable to a state-of-the art method. Our experiment demonstrates that deep learning is a valuable method for predicting protein torsion angles. The deep recurrent network architecture performs slightly better than deep feed-forward architecture, and the predicted residue contact number and the error distribution of torsion angles extracted from sequence fragments are useful features for improving prediction accuracy.

  2. Torsion angle preferences in druglike chemical space: a comprehensive guide.

    Science.gov (United States)

    Schärfer, Christin; Schulz-Gasch, Tanja; Ehrlich, Hans-Christian; Guba, Wolfgang; Rarey, Matthias; Stahl, Martin

    2013-03-14

    Crystal structure databases offer ample opportunities to derive small molecule conformation preferences, but the derived knowledge is not systematically applied in drug discovery research. We address this gap by a comprehensive and extendable expert system enabling quick assessment of the probability of a given conformation to occur. It is based on a hierarchical system of torsion patterns that cover a large part of druglike chemical space. Each torsion pattern has associated frequency histograms generated from CSD and PDB data and, derived from the histograms, traffic-light rules for frequently observed, rare, and highly unlikely torsion ranges. Structures imported into the corresponding software are annotated according to these rules. We present the concept behind the tree of torsion patterns, the design of an intuitive user interface for the management and usage of the torsion library, and we illustrate how the system helps analyze and understand conformation properties of substructures widely used in medicinal chemistry.

  3. Three-dimensional finite element analysis of critical pre-twist strain angle for torsional axis

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guo-feng; LI Xiao-yan; SHI Yao-wu; XU Bin-shi

    2005-01-01

    A three-dimensional elasto-plastic finite element analysis of pre-twist process for a torsional axis made of 45GrNiMoVA steel, was carried out using a commercial finite element analysis code, MSC MARC 2001. The results show that the critical pre-twist strain angle is 0. 027 rad and the maximum elastic shear stress after pre-twist is 1 694 MPa for the torsional axis.

  4. Measurement of torsion angles of long finger bones using computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Berthold, L.D. [Dept. of Pediatric Radiology, Justus Liebig Univ., Giessen (Germany); Univ. of Giessen (Germany). Dept. of Pediatric Radiology; Peter, A. [Dept. of Traumatology, Philipps Univ. Marburg (Germany); Ishaque, N.; Mauermann, F.; Klose, K.J. [Dept. of Diagnostic Radiology, Philipps Univ. Marburg (Germany); Boehringer, G. [Dept. of Traumatology, Justus Liebig Univ., Giessen (Germany)

    2001-10-01

    Objective: Rotational dislocation at the fracture site is a complication of long finger bone fractures of the metacarpals and phalanges. To evaluate such deformities, we performed CT of the articular surfaces of these bones to demonstrate the torsion angles. Design: We evaluated 10 pairs of cadaver hands. These were placed flat, with the bones of interest perpendicular to the gantry to acquire axial images. The torsion of the long bone axes was defined as the angle between a tangent positioned parallel to the proximal articular surface and a tangent parallel to the distal articular surface of individual bones. Results: The maximum difference between repeated measurements was 4 . Intraobserver differences measured between right and left hands are less than 3 . Conclusion: Side differences in torsion angles exceeding 3 are strongly suspicious of a malrotation after fracture. These measurements might help to plan derotational osteotomy and assess the results of therapy. (orig.)

  5. Flexural-torsional buckling analysis of angle-bar stiffened plates

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Rahbar Ranji [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2015-09-15

    The interaction of flexural-torsional buckling modes is critical for stiffened plates with asymmetric stiffeners. However, this interaction is ignored in all design rules because it is complex to characterize. In the literature, the presence of an attached plate is ignored, and stiffened plate is treated as an ordinary asymmetric beam. In the flexural buckling mode, stiffener and the attached plate buckle together; in the torsional buckling mode, the attached plate cannot freely rotate with stiffener. Basic equations of the flexural-torsional buckling modes are deduced based on hybrid beam concept and a new strain distribution assumption for sideway bending of stiffeners. Elastic buckling stresses of different angle-bar stiffened plates are calculated and compared with those generated by the Finite element method (FEM) and those available in the literature. The present method has better agreements with FEM.

  6. Outcomes of torsional microcoaxial phacoemulsification using tips with 30-degree and 45-degree aperture angles.

    Science.gov (United States)

    Helvacioglu, Firat; Sencan, Sadik; Yeter, Celal; Tunc, Zeki; Uyar, O Murat

    2014-03-01

    To compare the safety and efficacy of Ozil Intelligent Phaco torsional microcoaxial phacoemulsification surgeries performed using 30-degree and 45-degree aperture angled tips. Maltepe University School of Medicine Department of Ophthalmology, Istanbul, Turkey. Comparative case series. Eyes were assigned to 2.2 mm microcoaxial phacoemulsification using the torsional mode with a 45-degree (Group 1) or 30-degree (Group 2) aperture angled tip. A quick-chop surgical technique was used. The primary outcome measures were ultrasound time (UST), cumulative dissipated energy (CDE), longitudinal and torsional ultrasound (US) amplitudes, mean surgical time, mean balanced salt solution volume used, and mean central corneal thickness (CCT) changes. The mean UST, CDE, and longitudinal and torsional US amplitudes were 58.21 seconds ± 33.81 (SD), 7.74 ± 6.23, 0.45 ± 0.30, and 26.30 ± 12.60 in Group 1 and 63.83 ± 23.42 seconds, 12.36 ± 6.75, 0.23 ± 0.26, and 44.65 ± 14.38 in Group 2, respectively. The mean CDE and torsional amplitudes were significantly lower in Group 1 (P=.002 and P=.001, respectively). The mean balanced salt solution volume was 73.30 ± 19.87 cc in Group 1 and 74.30 ± 19.44 cc in Group 2 (P=.821). The mean CCT change was 52.40 ± 38.08 μm and 99.35 ± 47.14 μm, respectively (Ptip provided more effective lens removal with a lower CDE and less CCT change than a 30-degree aperture angled tip. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  7. A laser speckle sensor to measure the distribution of static torsion angles of twisted targets

    DEFF Research Database (Denmark)

    Rose, B.; Imam, H.; Hanson, Steen Grüner

    1998-01-01

    A novel method for measuring the distribution of static torsion angles of twisted targets is presented. The method is based on Fourier transforming the scattered field in the direction perpendicular to the twist axis, while performing an imaging operation in the direction parallel to the axis....... The Fourier transform serves to map the angular distribution of the scattered light field at the target into a linear displacement on a two-dimensional array image sensor placed in the Fourier plane. Measuring this displacement facilitates the determination of the angular displacement of the target....... A cylindrical lens serves to image the closely spaced lateral positions of the target along the twist axis onto corresponding lines of the two dimensional image sensor. Thus, every single line of the image sensor measures the torsion angle of the corresponding surface position along the twist axis of the target...

  8. Quantitative residue-specific protein backbone torsion angle dynamics from concerted measurement of 3J couplings.

    Science.gov (United States)

    Lee, Jung Ho; Li, Fang; Grishaev, Alexander; Bax, Ad

    2015-02-04

    Three-bond (3)J(C'C') and (3)J(HNHα) couplings in peptides and proteins are functions of the intervening backbone torsion angle ϕ. In well-ordered regions, (3)J(HNHα) is tightly correlated with (3)J(C'C'), but the presence of large ϕ angle fluctuations differentially affects the two types of couplings. Assuming the ϕ angles follow a Gaussian distribution, the width of this distribution can be extracted from (3)J(C'C') and (3)J(HNHα), as demonstrated for the folded proteins ubiquitin and GB3. In intrinsically disordered proteins, slow transverse relaxation permits measurement of (3)J(C'C') and (3)J(HNH) couplings at very high precision, and impact of factors other than the intervening torsion angle on (3)J will be minimal, making these couplings exceptionally valuable structural reporters. Analysis of α-synuclein yields rather homogeneous widths of 69 ± 6° for the ϕ angle distributions and (3)J(C'C') values that agree well with those of a recent maximum entropy analysis of chemical shifts, J couplings, and (1)H-(1)H NOEs. Data are consistent with a modest (≤30%) population of the polyproline II region.

  9. TAP score: torsion angle propensity normalization applied to local protein structure evaluation

    Directory of Open Access Journals (Sweden)

    Battistutta Roberto

    2007-05-01

    Full Text Available Abstract Background Experimentally determined protein structures may contain errors and require validation. Conformational criteria based on the Ramachandran plot are mainly used to distinguish between distorted and adequately refined models. While the readily available criteria are sufficient to detect totally wrong structures, establishing the more subtle differences between plausible structures remains more challenging. Results A new criterion, called TAP score, measuring local sequence to structure fitness based on torsion angle propensities normalized against the global minimum and maximum is introduced. It is shown to be more accurate than previous methods at estimating the validity of a protein model in terms of commonly used experimental quality parameters on two test sets representing the full PDB database and a subset of obsolete PDB structures. Highly selective TAP thresholds are derived to recognize over 90% of the top experimental structures in the absence of experimental information. Both a web server and an executable version of the TAP score are available at http://protein.cribi.unipd.it/tap/. Conclusion A novel procedure for energy normalization (TAP has significantly improved the possibility to recognize the best experimental structures. It will allow the user to more reliably isolate problematic structures in the context of automated experimental structure determination.

  10. Multiscale geometrical Lagrangian statistics: scale-dependent curvature and torsion angles in particle-laden turbulent flows

    Science.gov (United States)

    Schneider, Kai; Kadoch, Benjamin; Bassenne, Maxime; Esmaily-Moghadam, Mahdi; Farge, Marie; Bos, Wouter

    2016-11-01

    We present multiscale statistics of particle trajectories in isotropic turbulence and compare the behaviour of fluid and inertial particles. The directional change of inertial particles is quantified by considering the curvature angle for different time increments. Distinct scaling behaviors of the mean angle are observed for short, intermediate and long time lags. We also introduce the scale-dependent torsion angle, which quantifies the directional change of particles moving out of the plane. The influence of the Stokes and Reynolds numbers on the mean angles and on the probability distributions are analyzed. Finally, we assess the impact of LES and particle SGS modeling on those statistics. MF and KS thankfully acknowledge financial support from CTR, Stanford.

  11. Effect of Relative Marker Movement on the Calculation of the Foot Torsion Axis Using a Combined Cardan Angle and Helical Axis Approach

    Directory of Open Access Journals (Sweden)

    Eveline S. Graf

    2012-01-01

    Full Text Available The two main movements occurring between the forefoot and rearfoot segment of a human foot are flexion at the metatarsophalangeal joints and torsion in the midfoot. The location of the torsion axis within the foot is currently unknown. The purpose of this study was to develop a method based on Cardan angles and the finite helical axis approach to calculate the torsion axis without the effect of flexion. As the finite helical axis method is susceptible to error due to noise with small helical rotations, a minimal amount of rotation was defined in order to accurately determine the torsion axis location. Using simulation, the location of the axis based on data containing noise was compared to the axis location of data without noise with a one-sample t-test and Fisher's combined probability score. When using only data with helical rotation of seven degrees or more, the location of the torsion axis based on the data with noise was within 0.2 mm of the reference location. Therefore, the proposed method allowed an accurate calculation of the foot torsion axis location.

  12. Effect of relative marker movement on the calculation of the foot torsion axis using a combined Cardan angle and helical axis approach.

    Science.gov (United States)

    Graf, Eveline S; Wright, Ian C; Stefanyshyn, Darren J

    2012-01-01

    The two main movements occurring between the forefoot and rearfoot segment of a human foot are flexion at the metatarsophalangeal joints and torsion in the midfoot. The location of the torsion axis within the foot is currently unknown. The purpose of this study was to develop a method based on Cardan angles and the finite helical axis approach to calculate the torsion axis without the effect of flexion. As the finite helical axis method is susceptible to error due to noise with small helical rotations, a minimal amount of rotation was defined in order to accurately determine the torsion axis location. Using simulation, the location of the axis based on data containing noise was compared to the axis location of data without noise with a one-sample t-test and Fisher's combined probability score. When using only data with helical rotation of seven degrees or more, the location of the torsion axis based on the data with noise was within 0.2 mm of the reference location. Therefore, the proposed method allowed an accurate calculation of the foot torsion axis location.

  13. Studies on the Dihedral Angle and Torsional Barriers for 4,4′-Bipyridine

    Institute of Scientific and Technical Information of China (English)

    CHEN Wen-kai; LU Chun-hai; XU Jiao; LI Jun-qian

    2004-01-01

    Using the Hartree-Fock, MP2, and the B3LYP, BLYP, mPW1PW91 density functional methods, each combined with the 6-31G(d), 6-311G(d), 6-311+(d), 6-311++G(d, p) cc-pvdz and cc-pvtz basis sets, the equilibrium geometry of 4,4′ -bipyridine was optimized and the internal rotational potential barriers heights at 0° (AE0), 90° (AE90) were obtained. For the best basis set (cc-pvtz) , the predicted dihedral angle e ranges from 37.0 to 37.8° for all methods except the Hartree-Fock method (43.7). This agreed with the estimation from the electron diffraction experimental measurement (37.2°). The inter-ring C-C distance, ranging from 147.2 to 148.7 pm ( 147 pm experimental), is intermediate between the typical aromatic C-C bond and the aliphatic C-C bond. The results show that the inter-ring o-conjugation between two pyridyl rings stabilizes the co-planar conformer and the steric repulsion between the ortho neighboring hydrogens belonging to different rings favors the non-planar orthogonal conformer.

  14. Improving the prediction accuracy of residue solvent accessibility and real-value backbone torsion angles of proteins by guided-learning through a two-layer neural network.

    Science.gov (United States)

    Faraggi, Eshel; Xue, Bin; Zhou, Yaoqi

    2009-03-01

    This article attempts to increase the prediction accuracy of residue solvent accessibility and real-value backbone torsion angles of proteins through improved learning. Most methods developed for improving the backpropagation algorithm of artificial neural networks are limited to small neural networks. Here, we introduce a guided-learning method suitable for networks of any size. The method employs a part of the weights for guiding and the other part for training and optimization. We demonstrate this technique by predicting residue solvent accessibility and real-value backbone torsion angles of proteins. In this application, the guiding factor is designed to satisfy the intuitive condition that for most residues, the contribution of a residue to the structural properties of another residue is smaller for greater separation in the protein-sequence distance between the two residues. We show that the guided-learning method makes a 2-4% reduction in 10-fold cross-validated mean absolute errors (MAE) for predicting residue solvent accessibility and backbone torsion angles, regardless of the size of database, the number of hidden layers and the size of input windows. This together with introduction of two-layer neural network with a bipolar activation function leads to a new method that has a MAE of 0.11 for residue solvent accessibility, 36 degrees for psi, and 22 degrees for phi. The method is available as a Real-SPINE 3.0 server in http://sparks.informatics.iupui.edu.

  15. Determination of the torsion angles of alanine and glycine residues of model compounds of spider silk (AGG){sub 10} using solid-state NMR methods

    Energy Technology Data Exchange (ETDEWEB)

    Ashida, Jun; Ohgo, Kosuke; Komatsu, Kohei; Kubota, Ayumi; Asakura, Tetsuo [Tokyo University of Agriculture and Technology, Department of Biotechnology (Japan)], E-mail: asakura@cc.tuat.ac.jp

    2003-02-15

    Spiders synthesize several kinds of silk fibers. In the primary structure of spider silk, one of the major ampullate (dragline, frame) silks, spidroin 1, and flagelliform silk (core fibers of adhesive spiral), there are common repeated X-Gly-Gly (X = Ala, Leu, Pro, Tyr, Glu, and Arg) sequences, which are considered to be related to the elastic character of these fibers. In this paper, two dimensional spin diffusion solid-state NMR under off magic angle spinning (OMAS), {sup 13}C chemical shift contour plots, and Rotational Echo DOuble Resonance (REDOR) were applied to determine the torsion angles of one Ala and two kinds of Gly residues in the Ala-Gly-Gly sequence of {sup 13}C=O isotope-labeled (Ala-Gly-Gly){sub 10}. The torsion angles were determined to be ({phi}, {psi}) = (-90 deg., 150 deg.) within an experimental error of {+-}10 deg. for each residue. This conformation is characterized as 3{sub 1} helix which is in agreement with the structure proposed from the X-ray powder diffraction pattern of poly(Ala-Gly-Gly). The 3{sub 1} helix of (Ala-Gly-Gly){sub 10} does not change by formic acid treatment although (Ala-Gly){sub 15} easily changes from the silk I conformation (the structure of Bombyx mori silk fibroin before spinning in the solid state) to silk II conformation (the structure of the silk fiber after spinning) by such treatment. Thus, the 3{sub 1} helix conformation of (Ala-Gly-Gly){sub 10} is considered very stable. Furthermore, the torsion angles of the 16th Leu residue of (Leu-Gly-Gly){sub 10} were also determined as ({phi}, {psi}) = (-90 deg., 150 deg.) and this peptide is also considered to take 3{sub 1} helix conformation.

  16. A Novel Approach for Deriving Force Field Torsion Angle Parameters Accounting for Conformation-Dependent Solvation Effects.

    Science.gov (United States)

    Zgarbová, Marie; Luque, F Javier; Šponer, Jiří; Otyepka, Michal; Jurečka, Petr

    2012-09-11

    A procedure for deriving force field torsion parameters including certain previously neglected solvation effects is suggested. In contrast to the conventional in vacuo approaches, the dihedral parameters are obtained from the difference between the quantum-mechanical self-consistent reaction field and Poisson-Boltzmann continuum solvation models. An analysis of the solvation contributions shows that two major effects neglected when torsion parameters are derived in vacuo are (i) conformation-dependent solute polarization and (ii) solvation of conformation-dependent charge distribution. Using the glycosidic torsion as an example, we demonstrate that the corresponding correction for the torsion potential is substantial and important. Our approach avoids double counting of solvation effects and provides parameters that may be used in combination with any of the widely used nonpolarizable discrete solvent models, such as TIPnP or SPC/E, or with continuum solvent models. Differences between our model and the previously suggested solvation models are discussed. Improvements were demonstrated for the latest AMBER RNA χOL3 parameters derived with inclusion of solvent effects in a previous publication (Zgarbova et al. J. Chem. Theory Comput.2011, 7, 2886). The described procedure may help to provide consistently better force field parameters than the currently used parametrization approaches.

  17. Polysulfide anions II: structure and vibrational spectra of the S4(2-) and S5(2-) anions. Influence of the cations on bond length, valence, and torsion angle.

    Science.gov (United States)

    el Jaroudi, O; Picquenard, E; Demortier, A; Lelieur, J P; Corset, J

    2000-06-12

    The influence of the cations on bond length, valence, and torsion angle of S4(2-) and S5(2-) anions was examined in a series of solid alkali tetra- and pentasulfides by relating their Raman spectra to their known X-ray structures through a force-field analysis. The IR and Raman spectra of BaS4.H2O and the Raman spectra of (NH4)2S4.nNH3, gamma-Na2S4, and delta-Na2S5 are presented. The similarity of spectra of gamma-Na2S4 with those of BaS4.H2O suggests similar structures of the S4(2-) anions in these two compounds with a torsion angle smaller than 90 degrees. The variations of SS bond length, SSS valence angle, and dihedral angle of Sn2- anions are related to the polarization of the lone pair and electronic charge of the anion by the electric field of the cations. A correlation between the torsion angle and the SSS valence angle is shown as that previously reported between the length of the bond around which the torsion takes place and the dihedral angle value. These geometry changes are explained by the hyperconjugation concept and the electron long-pair repulsion.

  18. Torsion pendulum revisited

    CERN Document Server

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

    2013-01-01

    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.

  19. Structure-activity relationships for interaction with multidrug resistance protein 2 (ABCC2/MRP2): the role of torsion angle for a series of biphenyl-substituted heterocycles.

    Science.gov (United States)

    Lai, Yurong; Xing, Li; Poda, Gennadiy I; Hu, Yiding

    2007-06-01

    Multidrug resistance protein 2 (ABCC2/MRP2) is an ATP-binding cassette transporter involved in the absorption, distribution, and excretion of drugs and xenobiotics. Identifying compounds that are ABCC2/MRP2 substrates and/or inhibitors and understanding their structure-activity relationships (SARs) are important considerations in the selection and optimization of drug candidates. In the present study, the interactions between ABCC2/MRP2 and a series of biphenyl-substituted heterocycles were evaluated using Caco-2 cells and human ABCC2/MRP2 gene-transfected Madin-Darby canine kidney cells. It was observed that ABCC2/MRP2 transport and/or inhibition profile, both in nature and in magnitude, depends strongly on the substitution patterns of the biphenyl system. In particular, different ortho-substitutions cause various degrees of twisting between the two-phenyl rings, resulting in changing interactions between the ligands and ABCC2/MRP2. The compounds with small ortho functions (hydrogen, fluorine, and oxygen) and, thus, the ones displaying the smallest torsion angles of biphenyl (37-45 degrees) are neither substrates nor inhibitors of human ABCC2/MRP2. The transporter interactions increase as the steric bulkiness of the ortho-substitutions increase. When the tested compounds are 2-methyl substituted biphenyls, they exhibit moderate torsion angles (54-65 degrees) and behave as ABCC2/MRP2 substrates as well as mild inhibitors [10-40% compared with 3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethyl-sulfanyl)methylsulfanyl] propionic acid (MK571)]. For the 2,2'-dimethyl substituted biphenyls, the torsions are enhanced (78-87 degrees) and so is the inhibition of ABCC2/MRP2. This class of compounds behaves as strong inhibitors of ABCC2/MRP2. These results can be used to define the three-dimensional structural requirements of ABCC2/MRP2 interaction with their substrates and inhibitors, as well as to provide SAR guidance to support drug discovery.

  20. Binding of hairpin pyrrole and imidazole polyamides to DNA: relationship between torsion angle and association rate constants.

    Science.gov (United States)

    Han, Yong-Woon; Matsumoto, Tomoko; Yokota, Hiroaki; Kashiwazaki, Gengo; Morinaga, Hironobu; Hashiya, Kaori; Bando, Toshikazu; Harada, Yoshie; Sugiyama, Hiroshi

    2012-12-01

    N-methylpyrrole (Py)-N-methylimidazole (Im) polyamides are small organic molecules that bind to DNA with sequence specificity and can be used as synthetic DNA-binding ligands. In this study, five hairpin eight-ring Py-Im polyamides 1-5 with different number of Im rings were synthesized, and their binding behaviour was investigated with surface plasmon resonance assay. It was found that association rate (k(a)) of the Py-Im polyamides with their target DNA decreased with the number of Im in the Py-Im polyamides. The structures of four-ring Py-Im polyamides derived from density functional theory revealed that the dihedral angle of the Py amide carbonyl is 14∼18°, whereas that of the Im is significantly smaller. As the minor groove of DNA has a helical structure, planar Py-Im polyamides need to change their conformation to fit it upon binding to the minor groove. The data explain that an increase in planarity of Py-Im polyamide induced by the incorporation of Im reduces the association rate of Py-Im polyamides. This fundamental knowledge of the binding of Py-Im polyamides to DNA will facilitate the design of hairpin Py-Im polyamides as synthetic DNA-binding modules.

  1. (2S,4R)-4-hydroxyproline(4-nitrobenzoate): strong induction of stereoelectronic effects via a readily synthesized proline derivative. Crystallographic observation of a correlation between torsion angle and bond length in a hyperconjugative interaction.

    Science.gov (United States)

    Pandey, Anil K; Yap, Glenn P A; Zondlo, Neal J

    2014-05-01

    (2S,4R)-4-Hydroxyproline(4-nitrobenzoate) was synthesized. The crystal structure revealed an exo ring pucker, with the nitrobenzoate pseudoaxial on the pyrrolidine envelope and antiperiplanar to C(β) and C(δ) C-H bonds. The unit cell exhibited variation in C(δ)-H/C(γ)-O and C(β)-H/C(γ)-O torsion angles, with a 15° increase in torsion angle (148° to 163°) observed to result in a 0.018 Å decrease in C(δ)-H/C(γ)-O bond length, consistent with favorable σC-H → σ*C-O hyperconjugative interactions increasing with greater orbital overlap.

  2. Testicular torsion

    DEFF Research Database (Denmark)

    Brasso, K; Andersen, L; Kay, L;

    1993-01-01

    Thirty-five patients were examined 6-11 years after operation for torsion of the testis. Loss of testicular tissue was significantly associated with long preoperative duration of symptoms and with low postoperative sperm counts. The sex hormones were normal in the majority of patients but there w......Thirty-five patients were examined 6-11 years after operation for torsion of the testis. Loss of testicular tissue was significantly associated with long preoperative duration of symptoms and with low postoperative sperm counts. The sex hormones were normal in the majority of patients...

  3. Torsional locomotion

    Science.gov (United States)

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

    2014-01-01

    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

  4. Torsion profiling of proteins using magnetic particles.

    Science.gov (United States)

    van Reenen, A; Gutiérrez-Mejía, F; van IJzendoorn, L J; Prins, M W J

    2013-03-05

    We report a method to profile the torsional spring properties of proteins as a function of the angle of rotation. The torque is applied by superparamagnetic particles and has been calibrated while taking account of the magnetization dynamics of the particles. We record and compare the torsional profiles of single Protein G-Immunoglobulin G (IgG) and IgG-IgG complexes, sandwiched between a substrate and a superparamagnetic particle, for torques in the range between 0.5 × 10(3) and 5 × 10(3) pN·nm. Both molecular systems show torsional stiffening for increasing rotation angle, but the elastic and inelastic torsion stiffnesses are remarkably different. We interpret the results in terms of the structural properties of the molecules. The torsion profiling technique opens new dimensions for research on biomolecular characterization and for research on bio-nanomechanical structure-function relationships.

  5. Torsional Phacoemulsification and Tip Selection

    Directory of Open Access Journals (Sweden)

    Fırat Helvacıoğlu

    2014-10-01

    Full Text Available One of the recent advances in cataract surgery is torsional phacoemulsification. It was developed to increase the efficacy of ultrasonic emulsification. In torsional phacoemulsification, the torsional movement of the tip is translated to side-to-side cutting action with the aid of bent phaco tips. Lens material is cut in both directions, rather than only during a forward stroke. The efficiency of this technique is further enhanced by an improvement in followability provided by the inherent non-repulsive nature of the side-to-side motion. Tip selection is very important for the efficiency of torsional phacoemulsification. Theoretically, there are 2 ways to enhance the cutting efficiency of the tip. First is the stroke length; the 22-degree bent 30-degree Kelman mini-flared tip cuts longer than the 12-degree bent 30-degree mini-flared Kelman tip. Second is the angulation or bevel; the higher the degree (45 degrees, the better cutting efficiency. Retrospective analyses of the previously published clinical studies clearly demonstrated that the efficacy of the torsional phacoemulsification has positive correlation with both the aperture angles and neck angles of the tips. (Turk J Ophthalmol 2014; 44: 392-5

  6. Measurement of tibial torsion by computer tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jend, H.H.; Heller, M.; Dallek, M.; Schoettle, H. (Hamburg Univ. (Germany, F.R.))

    1981-01-01

    A CT procedure for objective measurements of tibial torsion independent of axial rotation in the nearby joints is described. Transverse sections in defined planes of the tibia permit easy calculation of normal and abnormal congenital or posttraumatic angles of torsion. In 69 limbs normal tibial torsion was 40/sup 0/+-9/sup 0/. In a series of 42 limbs with complicated healing of a fracture of both bones of the leg it is shown that tibial maltorsion is a deformity which in most cases leads to arthrosis of the ankle joint.

  7. Evaluation of left ventricular torsion by cardiovascular magnetic resonance

    Directory of Open Access Journals (Sweden)

    Young Alistair A

    2012-07-01

    Full Text Available Abstract Recently there has been considerable interest in LV torsion and its relationship with symptomatic and pre-symptomatic disease processes. Torsion gives useful additional information about myocardial tissue performance in both systolic and diastolic function. CMR assessment of LV torsion is simply and efficiently performed. However, there is currently a wide variation in the reporting of torsional motion and the procedures used for its calculation. For example, torsion has been presented as twist (degrees, twist per length (degrees/mm, shear angle (degrees, and shear strain (dimensionless. This paper reviews current clinical applications and shows how torsion can give insights into LV mechanics and the influence of LV geometry and myocyte fiber architecture on cardiac function. Finally, it provides recommendations for CMR measurement protocols, attempts to stimulate standardization of torsion calculation, and suggests areas of useful future research.

  8. Influence of the Torsion Angle in 3,3'-Dimethyl-2,2'-bipyridine on the Intermediate Valence of Yb in (C5Me5)2 Yb(3,3'-Me2-bipy)

    Energy Technology Data Exchange (ETDEWEB)

    Nocton, Gr& #233; gory; Booth, Corwin H.; Maron, Laurent; Andersen, Richard A.

    2014-06-26

    The synthesis and X-ray crystal structures of Cp-2*Yb(3,3'-Me(2)bipy) and [Cp-2 Yb(3,3'-Me(2)bipy)][Cp-2 YbCl1.6I0.4]center dot CH2Cl2 are described. In both complexes, the NCCN torsion angles are approximately 40 degrees. The temperature-independent value of n(f) of 0.17 shows that the valence of ytterbium in the neutral adduct is multiconfigurational, in reasonable agreement with a CASSCF calculation that yields a n(f) value of 0.27; that is, the two configurations in the wave function are f(13)(pi(1))(1) and f(14)(pi(1))(0) in a ratio of 0.27:0.73, respectively, and the open-shell singlet lies 0.28 eV below the triplet state (n(f) accounts for f-hole occupancy; that is, n(f) = 1 when the configuration is f(13) and n(f) = 0 when the configuration is f(14)). A correlation is outlined between the value of nf and the individual ytterbocene and bipyridine fragments such that, as the reduction potentials of the ytterbocene cation and the free x,x'-R-2-bipy ligands approach each other, the value of nf and therefore the f(13):f(14) ratio reaches a maximum; conversely, the ratio is minimized as the disparity increases.

  9. Superconducting Cosmic String with Propagating Torsion

    CERN Document Server

    Ferreira, C N; Garcia de Andrade, L C

    2000-01-01

    We show that it is possible to construct a consistent model describing a current-carrying cosmic string endowed with torsion. The torsion contribution to the gravitational force and geodesics of a test-particle moving around the SCCS are analyzed. In particular, we point out two interesting astrophysical phenomena in which the higher magnitude force we derived may play a critical role: the dynamics of compact objects orbiting the torsioned SCCS and accretion of matter onto it. The deficit angle associated to the SCCS can be obtained and compared with data from the Cosmic Background Explorer (COBE) satellite. We also derived a value for the torsion contribution to matter density fluctuations in the early Universe.

  10. Torsion gelometry of cheese.

    Science.gov (United States)

    Tunick, M H; Van Hekken, D L

    2002-11-01

    Torsion gelometry, a fundamental rheological test in which specimens are twisted until they fracture, was applied to several different cheese varieties to determine its suitability for measuring their textural properties. Fresh and aged Brick, Cheddar, Colby, Gouda, Havarti, Mozzarella, and Romano cheeses were subjected to torsion analysis, and the results were compared with those from small amplitude oscillatory shear (SAOS) tests and texture profile analysis (TPA). Strong relationships (correlation coefficients > 0.8) were found between torsion shear stress and TPA hardness, and between torsion shear strain and TPA cohesiveness. SAOS, which measures rheological properties of intact samples, did not correlate well with torsion or TPA. A map showing trends during aging toward brittle, mushy, rubbery, and tough texture was drawn using the torsion data. The findings show that torsion gelometry provides fundamental rheological data on cheese at the fracture point. The information can be used to compare textural qualities of cheese samples as they are being cut.

  11. Investigation of the torsional stiffness of flexible disc coupling

    Science.gov (United States)

    Buryy, A.; Simonovsky, V.; Obolonik, V.

    2017-08-01

    Calculation of flexible coupling torsional stiffness is required when analyzing the torsional vibrations of the reciprocating machinery train. While having the lowest torsional stiffness of all the elements of the train, flexible coupling has a significant influence on the natural frequencies of torsional vibration. However, considering structural complexity of coupling, precise definition of its torsional stiffness is quite a difficult task. The paper presents a method for calculating the torsional stiffness of flexible disc coupling based on the study of its finite element model response under the action of torque. The analysis of the basic parameters that quantitatively and qualitatively affect the coupling torsional stiffness has been also provided. The results of the calculation as well as model adequacy, sufficient for practical application, have been confirmed at the experimental measurement of flexible disc coupling torsional stiffness. The obtained elastic characteristics (dependences of applied torque and torsional stiffness versus twist angle) are nonlinear in the initial stage of loading. This feature should be taken into account when creating reliable mathematical models of torsional vibrations of reciprocating machinery trains containing flexible disc couplings.

  12. General Torsional Stiffness Matching of Off-road Vehicle

    Institute of Scientific and Technical Information of China (English)

    HUANG Song

    2009-01-01

    Increasing frame torsional stiffness of off-road vehicle will lead to the decrease of body torsional deformation, but the increase of torsional loads of flame and suspension system and the decrease of wheel adhesive weight. In severe case, a certain wheel will be out of contact with road surface. Appropriate matching of body, flame and suspension torsional stiffnesses is a difficult problem for off-road vehicle design. In this paper, these theoretically analytic models of the entire vehicle, body, frame and suspension torsional stiffness are constructed based on the geometry and mechanism of a light off-road vehicle's body, frame and suspension. The body and frame torsional stiffnesses can be calculated by applying body CAE method, meanwhile the suspension's rolling angle stiffness can be obtained by the bench test of the suspension's elastic elements. Through fixing the entire vehicle, using sole timber to raise wheels to simulate the road impact on a certain wheel, the entire vehicle torsional stiffness can be calculated on the geometric relation and loads of testing. Finally some appropriate matching principles of the body, frame and suspension torsional stiffness are summarized according to the test and analysis results. The conclusion can reveal the significance of the suspension torsional stiffness on off-road vehicle's torsion-absorbing capability. The results could serve as a reference for the design of other off-road vehicles.

  13. Affine Dynamics with Torsion

    CERN Document Server

    Gultekin, Kemal

    2015-01-01

    In this study, we give a thorough analysis of a general affine gravity with torsion. After a brief exposition of the affine gravities considered by Eddington and Schroedinger, we construct and analyze different affine gravities based on determinants of the Ricci tensor, torsion tensor, Riemann tensor and their combinations. In each case we reduce equations of motion to their simplest forms and give a detailed analysis of their solutions. Our analyses lead to construction of the affine connection in terms of curvature and torsion tensors. Our solutions of the dynamical equations show that curvature tensors at different points are correlated via non-local, exponential rescaling factors determined by the torsion tensor.

  14. Torsion formulation of gravity

    Energy Technology Data Exchange (ETDEWEB)

    Lledo, M A; Sommovigo, L, E-mail: Maria.Lledo@ific.uv.e, E-mail: Luca.Sommovigo@mfn.unipmn.i [Departament de Fisica Teorica, Universitat de Valencia, and IFIC (Centro mixto CSIC-UVEG) C/Dr Moliner, 50, E-46100 Burjassot (Valencia) (Spain)

    2010-03-21

    We explain precisely what it means to have a connection with torsion as a solution of the Einstein equations. While locally the theory remains the same, the new formulation allows for topologies that would have been excluded in the standard formulation of gravity. In this formulation it is possible to couple arbitrary torsion to gauge fields without breaking the gauge invariance.

  15. Twisted analytic torsion

    Institute of Scientific and Technical Information of China (English)

    MATHAI; Varghese

    2010-01-01

    We review the Reidemeister, Ray-Singer’s analytic torsion and the Cheeger-Mller theorem. We describe the analytic torsion of the de Rham complex twisted by a flux form introduced by the current authors and recall its properties. We define a new twisted analytic torsion for the complex of invariant differential forms on the total space of a principal circle bundle twisted by an invariant flux form. We show that when the dimension is even, such a torsion is invariant under certain deformation of the metric and the flux form. Under T-duality which exchanges the topology of the bundle and the flux form and the radius of the circular fiber with its inverse, the twisted torsion of invariant forms are inverse to each other for any dimension.

  16. Twisted Analytic Torsion

    CERN Document Server

    Mathai, Varghese

    2009-01-01

    We review the Reidemeister and Ray-Singer's analytic torsions and the Cheeger-M"uller theorem. We describe the analytic torsion of the de Rham complex twisted by a flux form introduced by the current authors and recall its properties. We define a new twisted analytic torsion for the complex of invariant differential forms on the total space of a principal circle bundle twisted by an invariant flux form. We show that when the dimension is even, such a torsion is invariant under certain deformation of the metric and the flux form. Under T-duality which exchanges the topology of the bundle and the flux form and the radius of the circular fiber with its inverse, the twisted torsions are inverse to each other for any dimensions.

  17. Apresentação de um novo dispositivo para mensuração do ângulo de torção da perna Evaluation of a new device for measuring the leg torsion angle

    Directory of Open Access Journals (Sweden)

    Sérgio José Lawand

    2004-06-01

    Full Text Available Variações rotacionais dos membros inferiores no plano transverso são responsáveis por um grande número de doenças que acometem crianças e indivíduos adultos. Nas crianças, podemos citar como exemplo, um quadro comum, a marcha com os "pés para dentro" ("toeing in" e nos indivíduos adultos, a incapacitante artrose degenerativa dos joelhos. Enquanto as alterações ósseas localizadas no plano transverso são difíceis de serem avaliadas, as deformidades presentes nos planos frontal e sagital podem ser avaliadas facilmente através, por exemplo, de simples radiografias. Neste contexto, dentre os métodos disponíveis para o estudo rotacional da perna, não há procedimento clínico ou de imagem que reúna as características de precisão, praticidade e baixo custo. Com o intuito de preencher esta lacuna, os autores apresentam um dispositivo para aferição clínica indireta do ângulo de torção da perna para indivíduos adultos e crianças. Neste artigo, procedeu-se a avaliação e a análise de 40 membros inferiores de cadáveres adultos humanos.Variations and deformities of lower limbs involving rotation in the transverse plane are associated with many clinical problems, ranging from harmless in-toing in children to disabling degenerative osteoarthritis of the knee in adult patients. While the bone alterations located in the transverse plane are difficult to be assessed, the frontal and sagittal deformities can be easily assessed , for instance, with the conventional radiographies. In this context, among the most available methods for the leg rotational study, there is not any clinical or image procedure which is more accurate, practical or with low cost. In order to solve this problem, the authors present a new device to indirect clinical standard of the leg torsion angle in adults and children. In this study, 40 lower limbs from human cadavers were assessed and analyzed.

  18. [Correlation analysis on the disorders of patella-femoral joint and torsional deformity of tibia].

    Science.gov (United States)

    Sun, Zhen-Jie; Yuan, Yi; Liu, Rui-Bo

    2015-03-01

    To reveal the possible mechanism involved in patella-femoral degenerative arthritis (PFDA) in- duced by torsion-deformity of tibia via analyzing the relationship between torsion-deformity of the tibia in patients with PFDA and the disorder of patella-femoral joint under the static and dynamic conditions. From October 2009 to October 2010, 50 patients (86 knees, 24 knees of male patients and 62 knees of female patients) with PFDA were classified as disease group and 16 people (23 knees, 7 knees of males and 16 knees of females) in the control group. The follow indexes were measured: the torsion-angle of tibia on CT scanning imagings, the patella-femoral congruence angle and lateral patella-femoral angle under static and dynamic conditions when the knee bent at 30 degrees of flexion. Based on the measurement results, the relationship between the torsion-deformity of tibias and the disorders of patella-femoral joints in patients with PFDA were analyzed. Finally,the patients were divided into three groups including large torsion-angle group, small torsion-angle group and normal group according to the size of torsion-angle, in order to analyze the relationship between torsion-deformity and disorders of patella-femoral joint, especially under the dynamic conditions. Compared with patients without PFDA, the ones with PFDA had bigger torsion-angle (30.30 ± 7.11)° of tibia, larger patella-femoral congruence angle (13.20 ± 3.94)° and smaller lateral patella-femoral angle (12.30 ± 3.04)°. The congruence angle and lateral patella-femoral angle under static and dynamic conditions had statistical differences respectively in both too-big torsion-angle group and too-small torsion-angle group. The congruence angle and lateral patella-femoral angle under static and dynamic conditions had no statistical differences in normal torsion-angle group. Torsion-deformity of tibia is the main reason for disorder of patella-femoral joint in the patients with PFDA. Torsion-deformity of

  19. [Omental torsion. Case Report].

    Science.gov (United States)

    Zaleta-Cruz, Janny Lizbeth; Rojas-Méndez, Javier; Garza-Serna, Ulises; González-Ruvalcaba, Román; Ortiz de Elguea-Lizarraga, José; Flores-Villalba, Eduardo

    Omental torsion is an infrequent cause of acute abdomen and its symptoms are non-specific, often presenting with pain at the right iliac fossa as the only symptom. Its aetiology remains unknown, but different risk factors have been associated with the disease, including obesity, congenital malformations, and tumours. These risk factors have been classified as predisposing or triggering, primary or secondary, and external or internal. The is a case of a 24-year-old male who complained about pain in the right iliac fossa without any other symptoms. The diagnosis was acute appendicitis, but during the laparoscopic approach, omental torsion was found. The diagnosis of omental torsion is is complex. However, computed tomography and ultrasound have been used successfully. The treatment for omental torsion is the resection of necrotised tissue by a laparoscopic approach. Copyright © 2015 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

  20. Affine dynamics with torsion

    Energy Technology Data Exchange (ETDEWEB)

    Gueltekin, Kemal [Izmir Institute of Technology, Department of Physics, Izmir (Turkey)

    2016-03-15

    In this study, we give a thorough analysis of a general affine gravity with torsion. After a brief exposition of the affine gravities considered by Eddington and Schroedinger, we construct and analyze different affine gravities based on the determinants of the Ricci tensor, the torsion tensor, the Riemann tensor, and their combinations. In each case we reduce equations of motion to their simplest forms and give a detailed analysis of their solutions. Our analyses lead to the construction of the affine connection in terms of the curvature and torsion tensors. Our solutions of the dynamical equations show that the curvature tensors at different points are correlated via non-local, exponential rescaling factors determined by the torsion tensor. (orig.)

  1. Torsional Strengthening of RC Beams Using GFRP Composites

    Science.gov (United States)

    Patel, Paresh V.; Jariwala, Vishnu H.; Purohit, Sharadkumar P.

    2016-09-01

    Fiber reinforced polymer as an external reinforcement is used extensively for axial, flexural and shear strengthening in structural systems. The strengthening of members subjected to torsion is recently being explored. The loading mechanism of beams located at the perimeter of buildings which carry loads from slabs, joists and beams from one side of the member generates torsion that are transferred from the beams to the columns. In this work an experimental investigation on the improvement of the torsional resistance of reinforced concrete beams using Glass Fiber Reinforced Polymer (GFRP) is presented. Total 24 RC beams have been cast in this work. Ten beams of dimension 150 mm × 150 mm × 1300 mm are subjected to pure torsion while fourteen beams of 150 mm × 150 mm × 1700 mm are subjected to combined torsion and bending. Two beams in each category are designated as control specimen and remaining beams are strengthened by GFRP wrapping of different configurations. Pure torsion on specimens is applied using specially fabricated support mechanism and universal testing machine. For applying combined torsion and bending a loading frame and test set up are fabricated. Measurements of angle of twist at regular interval of torque, torsion at first crack, and ultimate torque, are obtained for all specimens. Results of different wrapping configurations are compared for control and strengthened beams to suggest effective GFRP wrapping configuration.

  2. Higher Franz-Reidemeister torsion

    CERN Document Server

    Igusa, Kiyoshi

    2002-01-01

    The book is devoted to the theory of topological higher Franz-Reidemeister torsion in K-theory. The author defines the higher Franz-Reidemeister torsion based on Volodin's K-theory and Borel's regulator map. He describes its properties and generalizations and studies the relation between the higher Franz-Reidemeister torsion and other torsions used in K-theory: Whitehead torsion and Ray-Singer torsion. He also presents methods of computing higher Franz-Reidemeister torsion, illustrates them with numerous examples, and describes various applications of higher Franz-Reidemeister torsion, particularly for the study of homology of mapping class groups. Packed with up-to-date information, the book provides a unique research and reference tool for specialists working in algebraic topology and K-theory.

  3. Isolated Fallopian Tube Torsion

    Directory of Open Access Journals (Sweden)

    S. Kardakis

    2013-01-01

    Full Text Available Isolated torsion of the Fallopian tube is a rare gynecological cause of acute lower abdominal pain, and diagnosis is difficult. There are no pathognomonic symptoms; clinical, imaging, or laboratory findings. A preoperative ultrasound showing tubular adnexal masses of heterogeneous echogenicity with cystic component is often present. Diagnosis can rarely be made before operation, and laparoscopy is necessary to establish the diagnosis. Unfortunately, surgery often is performed too late for tube conservation. Isolated Fallopian tube torsion should be suspected in case of acute pelvic pain, and prompt intervention is necessary.

  4. Analytical and numerical models to predict the behavior of unbonded flexible risers under torsion

    Science.gov (United States)

    Ren, Shao-fei; Xue, Hong-xiang; Tang, Wen-yong

    2016-04-01

    This paper presents analytical and numerical models to predict the behavior of unbonded flexible risers under torsion. The analytical model takes local bending and torsion of tensile armor wires into consideration, and equilibrium equations of forces and displacements of layers are deduced. The numerical model includes lay angle, cross-sectional profiles of carcass, pressure armor layer and contact between layers. Abaqus/Explicit quasi-static simulation and mass scaling are adopted to avoid convergence problem and excessive computation time caused by geometric and contact nonlinearities. Results show that local bending and torsion of helical strips may have great influence on torsional stiffness, but stress related to bending and torsion is negligible; the presentation of anti-friction tapes may have great influence both on torsional stiffness and stress; hysteresis of torsion-twist relationship under cyclic loading is obtained by numerical model, which cannot be predicted by analytical model because of the ignorance of friction between layers.

  5. Analytical and Numerical Models to Predict the Behaviorof Unbonded Flexible Risers Under Torsion

    Institute of Scientific and Technical Information of China (English)

    任少飞; 薛鸿祥; 唐文勇

    2016-01-01

    This paper presents analytical and numerical models to predict the behavior of unbonded flexible risers under torsion. The analytical model takes local bending and torsion of tensile armor wires into consideration, and equilibrium equations of forces and displacements of layers are deduced. The numerical model includes lay angle, cross-sectional profiles of carcass, pressure armor layer and contact between layers. Abaqus/Explicit quasi-static simulation and mass scaling are adopted to avoid convergence problem and excessive computation time caused by geometric and contact nonlinearities. Results show that local bending and torsion of helical strips may have great influence on torsional stiffness, but stress related to bending and torsion is negligible; the presentation of anti-friction tapes may have great influence both on torsional stiffness and stress; hysteresis of torsion-twist relationship under cyclic loading is obtained by numerical model, which cannot be predicted by analytical model because of the ignorance of friction between layers.

  6. "Exotic" black holes with torsion

    OpenAIRE

    2013-01-01

    In the context of three-dimensional gravity with torsion, the concepts of standard and "exotic" Banados-Teitelboim-Zanelli black holes are generalized by going over to black holes with torsion. This approach provides a unified insight into thermodynamics of black holes, with or without torsion.

  7. Management of adnexal torsion

    Directory of Open Access Journals (Sweden)

    Neslihan Erkal

    2014-03-01

    Full Text Available Objective: To evaluate clinical findings, operative reports, the pathological results of patients with diagnosis of adnexal torsion. Methods: Fourteen patients with diagnosis of adnexal torsion who presented to our clinic between January 2009 and March 2013 were included in this retrospective analysis. Data including clinical findings, operative reports, the pathological results were recorded. Results: The mean age of the patients was 28.1 ± 10.5 with a range of 16 to 52 years. All patients underwent ultrasonography, and a pelvic mass appearance was detected in all cases. The mean diameter of the mass was 8,04±2,96 cm. All of the patients had lower abdominal pain, nausea and vomiting. Six patients were operated laparoscopically, while eight patients had laparotomy. Detorsion and cystectomy was performed in 7 (50.0% of the patients. Two of patients were pregnant in operation time that treated by cystectomy and detorsion of the ovaries successfully in the first and third trimester (one by laparoscopy. There was one patient of isolated fallopian tube torsion due to hydrosalpinks treated by laparoscopic salpingectomy. Two of the patients had paratubal cyst and tubal torsion. Detorsion and cystectomy by laparoscopy and salpingectomy by laparotomy were performed for these patients respectively. The most common histopathology was serous cystadenoma (28,6%. Conclusion: Adnexal torsion is a rare gynecologic emergency of women and occur in reproductive ages mostly. Prompt diagnosis and conservative treatment is important for the safety of ovaries and fallopian tubes and future fertility. J Clin Exp Invest 2014; 5 (1: 7-11

  8. Torsional dynamics of steerable needles: modeling and fluoroscopic guidance.

    Science.gov (United States)

    Swensen, John P; Lin, MingDe; Okamura, Allison M; Cowan, Noah J

    2014-11-01

    Needle insertions underlie a diversity of medical interventions. Steerable needles provide a means by which to enhance existing needle-based interventions and facilitate new ones. Tip-steerable needles follow a curved path and can be steered by twisting the needle base during insertion, but this twisting excites torsional dynamics that introduce a discrepancy between the base and tip twist angles. Here, we model the torsional dynamics of a flexible rod-such as a tip-steerable needle-during subsurface insertion and develop a new controller based on the model. The torsional model incorporates time-varying mode shapes to capture the changing boundary conditions inherent during insertion. Numerical simulations and physical experiments using two distinct setups-stereo camera feedback in semitransparent artificial tissue and feedback control with real-time X-ray imaging in optically opaque artificial tissue-demonstrate the need to account for torsional dynamics in control of the needle tip.

  9. Multiscale modeling and simulation of nanotube-based torsional oscillators

    Directory of Open Access Journals (Sweden)

    Xiao Shaoping

    2006-01-01

    Full Text Available AbstractIn this paper, we propose the first numerical study of nanotube-based torsional oscillators via developing a new multiscale model. The edge-to-edge technique was employed in this multiscale method to couple the molecular model, i.e., nanotubes, and the continuum model, i.e., the metal paddle. Without losing accuracy, the metal paddle was treated as the rigid body in the continuum model. Torsional oscillators containing (10,0 nanotubes were mainly studied. We considered various initial angles of twist to depict linear/nonlinear characteristics of torsional oscillators. Furthermore, effects of vacancy defects and temperature on mechanisms of nanotube-based torsional oscillators were discussed.

  10. Effect of tensile and torsion on GMI in amorphous wire

    Science.gov (United States)

    Blanco, J. M.; Zhukov, A.; Gonzalez, J.

    1999-05-01

    GMI effect, Δ Z/Z = [ Z( H) - Z( Hmax)]/ Z( Hmax) has been measured in (Fe 0.94Co 0.06) 72.5B 15Si 12.5 wire under tensile, σ ten, and torsional, σ tor, stresses. Generally Δ Z/Z( H) dependence has a non-monotonic shape with a maximum at certain axial magnetic field, Hm. Both tension and torsion modify Δ Z/Z( H) dependence. Application of tension results in an increase of Hm with σ ten. Torsional stress dependence of GMI effect has asymmetry with a maximum at torsion angle, φ, around + 12π/m in as-cast wire, when Δ Z/Z is around 250%. An increase of Δ Z/Zm up to 350% and change of Δ Z/Z(φ) dependence towards a nearly symmetric shape have been observed after Joule heating.

  11. Discrete torsion defects

    CERN Document Server

    Brunner, Ilka; Plencner, Daniel

    2014-01-01

    Orbifolding two-dimensional quantum field theories by a symmetry group can involve a choice of discrete torsion. We apply the general formalism of `orbifolding defects' to study and elucidate discrete torsion for topological field theories. In the case of Landau-Ginzburg models only the bulk sector had been studied previously, and we re-derive all known results. We also introduce the notion of `projective matrix factorisations', show how they naturally describe boundary and defect sectors, and we further illustrate the efficiency of the defect-based approach by explicitly computing RR charges. Roughly half of our results are not restricted to Landau-Ginzburg models but hold more generally, for any topological field theory. In particular we prove that for a pivotal bicategory, any two objects of its orbifold completion that have the same base are orbifold equivalent. Equivalently, from any orbifold theory (including those based on nonabelian groups) the original unorbifolded theory can be be obtained by orbifo...

  12. Molecular dynamics simulation on mechanical property of carbon nanotube torsional deformation

    Institute of Scientific and Technical Information of China (English)

    Chen Ming-Jun; Liang Ying-Chun; Li Hong-Zhu; Li Dan

    2006-01-01

    In this paper torsional deformation of the carbon nanotubes is simulated by molecular dynamics method. The Brenner potential is used to set up the simulation system. Simulation results show that the carbon nanotubes can bear larger torsional deformation, for the armchair type (10,10) single wall carbon nanotubes, with a yielding phenomenon taking place when the torsional angle is up to 63°(1.1rad). The influence of carbon nanotube helicity in torsional deformation is very small. The shear modulus of single wall carbon nanotubes should be several hundred GPa, not 1 GPa as others reports.

  13. Inferior oblique weakening surgery on ocular torsion in congenital superior oblique palsy

    Directory of Open Access Journals (Sweden)

    Jinho Lee

    2015-06-01

    Full Text Available AIM:To investigate changes in fundus excyclotorsion after inferior oblique myectomy or myotomy.METHODS:The records of 21 patients undergoing strabismus surgery by a single surgeon between 2009 and 2012 were examined. Only patients who had undergone an inferior oblique myectomy or myotomy, with or without horizontal rectus muscle surgery, were evaluated. Digital fundus photographs were obtained, and the angle formed by a horizontal line passing through the optic disc center and a reference line connecting the foveola and optic disc center was measured. Associated clinical factors examined include age at the time of surgery, presence or absence of a head tilt, degree of preoperative vertical deviation, torsional angle, inferior oblique muscle overaction/superior oblique muscle underaction, and surgery laterality. Whether the procedure was performed alone or in combination with a horizontal rectus muscle surgery was also examined.RESULTS:Mean preoperative torsional angle was 12.0±6.4°, which decreased to 6.9±5.7° after surgery (P<0.001, paired t-test. Torsional angle also decreased from 15.1±7.0° to 6.2±4.3° in the myectomy group (P<0.001, paired t-test but there were no significant changes in the myotomy group (P=0.093, Wilcoxon signed rank test. Multivariable linear regression analysis showed that preoperative torsional angle, degree of inferior oblique overaction, and age at surgery independently and significantly affected postoperative torsional angle.CONCLUSION:Mean torsional angle decreased after inferior oblique myectomy. Degree of preoperative torsional angle, inferior oblique overaction, and age at surgery influence postoperative torsional angle.

  14. Torsional Rigidity of Minimal Submanifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, Vicente

    2006-01-01

    We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...... for the torsional rigidity are actually attained and give conditions under which the geometric average of the stochastic mean exit time for Brownian motion at infinity is finite....

  15. Control and femtosecond time-resolved imaging of torsion in a chiral molecule

    CERN Document Server

    Hansen, Jonas L; Madsen, Christian Bruun; Lindhardt, Anders Thyboe; Johansson, Mikael P; Skrydstrup, Troels; Madsen, Lars Bojer; Stapelfeldt, Henrik

    2012-01-01

    We study how the combination of long and short laser pulses, can be used to induce torsion in an axially chiral biphenyl derivative (3,5-difluoro-3',5'-dibromo-4'-cyanobiphenyl). A long, with respect to the molecular rotational periods, elliptically polarized laser pulse produces 3D alignment of the molecules, and a linearly polarized short pulse initiates torsion about the stereogenic axis. The torsional motion is monitored in real-time by measuring the dihedral angle using femtosecond time-resolved Coulomb explosion imaging. Within the first 4 picoseconds, torsion occurs with a period of 1.25 picoseconds and an amplitude of 3 degrees in excellent agreement with theoretical calculations. At larger times the quantum states of the molecules describing the torsional motion dephase and an almost isotropic distribution of the dihedral angle is measured. We demonstrate an original application of covariance analysis of two-dimensional ion images to reveal strong correlations between specific ejected ionic fragments...

  16. Search for torsional oscillations in isolated sunspots

    Science.gov (United States)

    Griñón-Marín, A. B.; Socas-Navarro, H.; Centeno, R.

    2017-07-01

    In this work we seek evidence for global torsional oscillations in alpha sunspots. We have used long time series of continuum intensity and magnetic field vector maps from the Helioseismic and Magnetic Imager (HMI) instrument on board the Solar Dynamics Observatory (SDO) spacecraft. The time series analysed here span the total disk passage of 25 isolated sunspots. We found no evidence of global long-term periodic oscillations in the azimuthal angle of the sunspot magnetic field within 1 degree. This study could help us to understand the sunspot dynamics and its internal structure.

  17. Biothermal sensing of a torsional artificial muscle

    Science.gov (United States)

    Lee, Sung-Ho; Kim, Tae Hyeob; Lima, Márcio D.; Baughman, Ray H.; Kim, Seon Jeong

    2016-02-01

    Biomolecule responsive materials have been studied intensively for use in biomedical applications as smart systems because of their unique property of responding to specific biomolecules under mild conditions. However, these materials have some challenging drawbacks that limit further practical application, including their speed of response and mechanical properties, because most are based on hydrogels. Here, we present a fast, mechanically robust biscrolled twist-spun carbon nanotube yarn as a torsional artificial muscle through entrapping an enzyme linked to a thermally sensitive hydrogel, poly(N-isopropylacrylamide), utilizing the exothermic catalytic reaction of the enzyme. The induced rotation reached an equilibrated angle in less than 2 min under mild temperature conditions (25-37 °C) while maintaining the mechanical properties originating from the carbon nanotubes. This biothermal sensing of a torsional artificial muscle offers a versatile platform for the recognition of various types of biomolecules by replacing the enzyme, because an exothermic reaction is a general property accompanying a biochemical transformation.Biomolecule responsive materials have been studied intensively for use in biomedical applications as smart systems because of their unique property of responding to specific biomolecules under mild conditions. However, these materials have some challenging drawbacks that limit further practical application, including their speed of response and mechanical properties, because most are based on hydrogels. Here, we present a fast, mechanically robust biscrolled twist-spun carbon nanotube yarn as a torsional artificial muscle through entrapping an enzyme linked to a thermally sensitive hydrogel, poly(N-isopropylacrylamide), utilizing the exothermic catalytic reaction of the enzyme. The induced rotation reached an equilibrated angle in less than 2 min under mild temperature conditions (25-37 °C) while maintaining the mechanical properties

  18. Torsion testing of bed joints

    DEFF Research Database (Denmark)

    Hansen, Klavs Feilberg; Pedersen, Carsten Mørk

    2008-01-01

    This paper describes a simple test method for determining the torsion strength of a single bed joint between two bricks and presents results from testing using this test method. The setup for the torsion test is well defined, require minimal preparation of the test specimen and the test can...... be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....

  19. Gravitation Is Torsion

    CERN Document Server

    Schucking, Engelbert L

    2008-01-01

    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.

  20. A STUDY ON TIBIAL TORSION IN ADULT DRY TIBIA OF EAST AND SOUTH INDIAN POPULATION

    Directory of Open Access Journals (Sweden)

    Jami Sagar Prusti

    2017-05-01

    Full Text Available BACKGROUND Rotational deformities of the lower limbs are very common. There is increasing evidence that abnormal torsion in the tibia is associated with severe knee and ankle arthritis. Primary knee osteoarthritis is a leading cause of disability in older persons. Varus or valgus alignment increases the risk of osteoarthritis. Coexistence of tibial torsional deformity may increase the risk further. Variability in the tibial torsion has been reported and is due to the torsional forces applied on tibia during development. The aim of the study is to estimate the angle of tibial torsion on both sides and both sexes. The present study was an attempt to provide baseline data of tibial torsion in the East and South Indian population. MATERIALS AND METHODS The study was conducted mechanically on 100 dry adult unpaired human tibia, i.e. 50 male and 50 female bones. The measurements were recorded and statistically analysed using Student’s unpaired t-test using GraphPad Prism 5.0 (free trial version. RESULTS Out of the 100 tibia undertaken, mean value of tibial torsion angle obtained is 25.8°. In males, it is 23.68° and in females it is about 27.86°. Statistical analysis revealed significant greater average angle of tibial torsion in female bones. The angle of the right-sided bones was more and this was statistically significant. CONCLUSION The gender variation for the angle could be the result of the difference in lifestyle in day-to-day activities. The knowledge of the angle in a population could be helpful in understanding the incidence of pathogenesis related to gait and knee osteoarthritis and in view of reconstructive surgeries in orthopaedic practice.

  1. Torsion Effects and LLG Equation

    CERN Document Server

    Ferreira, Cristine N; Neto, J A Helayël

    2016-01-01

    Based on the non-relativistic regime of the Dirac equation coupled to a torsion pseudo-vector, we study the dynamics of magnetization and how it is affected by the presence of torsion. We consider that torsion interacting terms in Dirac equation appear in two ways one of these is thhrough the covariant derivative considering the spin connection and gauge magnetic field and the other is through a non-minimal spin torsion coupling. We show within this framework, that it is possible to obtain the most general Landau, Lifshitz and Gilbert (LLG) equation including the torsion effects, where we refer to torsion as a geometric field playing an important role in the spin coupling process. We show that the torsion terms can give us two important landscapes in the magnetization dynamics: one of them related with damping and the other related with the screw dislocation that give us a global effect like a helix damping sharped. These terms are responsible for changes in the magnetization precession dynamics.

  2. Re-torsion of the ovaries

    DEFF Research Database (Denmark)

    Hyttel, Trine E W; Bak, Geske S; Larsen, Solveig B;

    2015-01-01

    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...

  3. Torsion testing of bed joints

    DEFF Research Database (Denmark)

    Hansen, Klavs Feilberg; Pedersen, Carsten Mørk

    2008-01-01

    be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....

  4. Hematosalpinx torsion in an adolescent

    Directory of Open Access Journals (Sweden)

    Inês Vaz

    2016-02-01

    Full Text Available Introduction: Isolated fallopian tube torsion is an uncommon cause of acute lower abdominal pain. Ectopic pregnancy, hydro or hematosalpinx, endometriosis, adnexal masses and other causes of adnexal disease are predisposing factors. The diagnosis is difficult and often delayed due to the lack of pathognomonic symptoms, characteristic physical signs, and specific imaging and laboratory studies. Defi nitive diagnosis requires a surgical approach. Case report: The authors present a case of hematosalpinx and its tubal torsion in a virgin teenager with no prior predisposing factors. Discussion: This rare case may highlight a new insight into pathophysiology of tubal torsion and recalls hematosalpinx as a differential diagnosis.

  5. Index Theorems on Torsional Geometries

    CERN Document Server

    Kimura, Tetsuji

    2007-01-01

    We study various topological invariants on a differential geometry in the presence of a totally anti-symmetric torsion H under the closed condition dH=0. By using the identification between the Clifford algebra on a geometry and the canonical quantization condition of fermion in the quantum mechanics, we construct the N=1 quantum mechanical sigma model in the Hamiltonian formalism and extend this model to N=2 system, equipped with the totally anti-symmetric tensor associated with the torsion on the target space geometry. Next we construct transition elements in the Lagrangian path integral formalism and apply them to the analyses of the Witten indices in supersymmetric systems. We improve the formulation of the Dirac index on the torsional geometry which has already been studied. We also formulate the Euler characteristic and the Hirzebruch signature on the torsional geometry.

  6. TORSION OF HEMATOSALPINX WITH HEMOPERITONEUM

    Directory of Open Access Journals (Sweden)

    Lakshmikantha

    2013-02-01

    Full Text Available ABSTRACT: In cases presenting with hemoperitoneum diagnosis of ruptured ectopic pregnancy should be made unless proved otherwise during reprodu ctive age. Rarely ruptured ovarian cyst may be a cause. Hematosalpinx can undergo torsion du e to circulatory imbalance and the same can present as hemoperitoneum due to rupture. We presen t a rare case of torsion of hematosalpinx without an obvious rupture presenting as hemoperitoneum.

  7. Analytic torsion and symplectic volume

    DEFF Research Database (Denmark)

    McLellan, Brendan Donald Kenneth

    2013-01-01

    This article studies the abelian analytic torsion on a closed, oriented, quasi-regular Sasakian three-manifold and identifies this quantity as a specific multiple of the natural unit symplectic volume form on the moduli space of flat abelian connections. This identification effectively computes...... the analytic torsion explicitly in terms of Seifert data for a given quasi-regular Sasakian structure on a three-manifold....

  8. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    2015-01-01

    We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2) Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We...... present a thorough investigation of the intrinsic torsion of such structures, leading to the construction of explicit Lie group examples with invariant intrinsic torsion....

  9. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough inv...... investigation of the intrinsic torsion of such structures; in addition to the construction of harmonic structures, this analysis leads to explicit Lie group examples with invariant intrinsic torsion....

  10. Measurement of ocular torsion variation following superior oblique tenectomy

    Directory of Open Access Journals (Sweden)

    Bruna Lana Ducca

    2014-12-01

    Full Text Available Purposes: To objectively evaluate the torsional effect of the superior oblique muscle-weakening surgery using the tenectomy technique proposed by Souza-Dias. Methods: The present prospective study included 10 patients (20 eyes with horizontal strabismus, bilateral superior oblique overaction and A-pattern of 15 to 30 prism diopters who underwent superior oblique tenectomy. Objective assessment of ocular torsion was performed by retinography immediately before and one month after surgery. The amount of ocular torsion was determined by measuring the angle formed by a horizontal line drawn across the geometric center of the optic disc and a second line connecting this point to the fovea. Results: The median preoperative angle was 5.56° in the right eyes and -3.43° in the left eyes. The median postoperative angle was 1.84° in the right eyes and -3.12° in the left eyes. The angle variation was statistically significant in both eyes (p=0.012 and p=0.01, respectively. Conclusion: The present study suggests that superior oblique tenectomy has an extorter effect, decreasing the intorsion detected on overaction of this muscle.

  11. Ocular torsion variation after superior oblique weakening procedure - a case report

    Directory of Open Access Journals (Sweden)

    Bruna Lana Ducca

    2012-09-01

    Full Text Available Purpose: to objectively evaluate the torsional effect of the tenectomy of the superior oblique muscle (SO. Design: case report of one of the patients of the group studied in the previous paper "Measurement of the ocular torsion variation after superior oblique tenectomy". Methods: case report of a patient with horizontal strabismus and bilateral SO muscle overaction who was submitted to bilateral SO tenectomy. Obejective access of ocular torsion was held by retinogrphy and a computer software (Autocad 2009. Results: the preoperative angle was 7.57 in the right eye and 0.66 in the left eye. Postoperative torsion angle was 4.22 in the right eye and -1.50 the left eye. Conclusion: the present case suggests that SO tenectomy has an extorter effect, decreasing the intorsion detected in case of SO overaction.

  12. Multidimensional Seismic Control by Tuned Mass Damper with Poles and Torsional Pendulums

    Directory of Open Access Journals (Sweden)

    Haoxiang He

    2017-01-01

    Full Text Available Due to the eccentric characteristics and the torsional excitation of multidimensional earthquakes, the dynamic response of asymmetry structure involves the translation-torsion coupling vibration and it is adverse to structural performance. Although the traditional tuned mass damper (TMD is effective for decreasing the translational vibration when the structure is subjected to earthquake, its translation-torsion coupled damping capacity is still deficient. In order to simultaneously control the translational responses and the torsional angle of asymmetry structures, a new type of tuned mass damper with tuned mass blocks, orthogonal poles, and torsional pendulums (TMDPP is proposed. The translation-torsion coupled vibration is tuned by the movement of the mass blocks and the torsional pendulums. According to the composition and the motion mechanism of the TMDPP, the dynamic equation for the total system considering eccentric torsion effect is established. The damping capacity of the TMDPP is verified by the time history analysis of an eccentric structure, and multidimensional earthquake excitations are considered. The damping effect of the traditional TMD and the TMDPP is compared, and the results show that the performance of TMDPP is superior to the traditional TMD. Moreover, the occasional amplitude amplification in TMD control does not appear in the TMDPP control. The main design parameters which affect the damping performance of TMDPP are analyzed.

  13. Stability and bifurcation behaviour of electrostatic torsional NEMS varactor influenced by dispersion forces

    Energy Technology Data Exchange (ETDEWEB)

    Lin Wenhui [College of Science, China Agricultural University, Beijing 100083 (China); Zhao Yapu [State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080 (China)

    2007-03-21

    The influences of Casimir and van der Waals forces on the nano-electromechanical systems (NEMS) electrostatic torsional varactor are studied. A one degree of freedom, the torsional angle, is adopted, and the bifurcation behaviour of the NEMS torsional varactor is investigated. There are two bifurcation points, one of which is a Hopf bifurcation point and the other is an unstable saddle point. The phase portraits are also drawn, in which periodic orbits are around the Hopf bifurcation point, but the periodic orbit will break into a homoclinic orbit when meeting the unstable saddle point.

  14. Stability and bifurcation behaviour of electrostatic torsional NEMS varactor influenced by dispersion forces

    Science.gov (United States)

    Lin, Wen-Hui; Zhao, Ya-Pu

    2007-03-01

    The influences of Casimir and van der Waals forces on the nano-electromechanical systems (NEMS) electrostatic torsional varactor are studied. A one degree of freedom, the torsional angle, is adopted, and the bifurcation behaviour of the NEMS torsional varactor is investigated. There are two bifurcation points, one of which is a Hopf bifurcation point and the other is an unstable saddle point. The phase portraits are also drawn, in which periodic orbits are around the Hopf bifurcation point, but the periodic orbit will break into a homoclinic orbit when meeting the unstable saddle point.

  15. Thin-Walled Beam Theories and Their Applications in the Torsional Strength Analysis of Ship Hulls.

    Science.gov (United States)

    1987-01-01

    numerous deep web frames and transverse bulkheads. The system has been utilized in a study of a frigate under an assumed torsional/flexural load, the...transverse bulkheads and r deep web frames. Figure 18 indicates that, despite the poor agreement in twist angle, the axial stress results compare quite...under torsional loads. This will be the case for a typical warship hull, because of the large number of deep web frames and transverse bulkheads. The

  16. Testicular torsion in children: Scintigraphic assessment

    Energy Technology Data Exchange (ETDEWEB)

    Mendel, J.B.; Taylor, G.A.; Cheng, T.H.; Retik, A.; Bauer, S.; Treves, S.

    1985-02-01

    Seventy-five patients with suspected testicular torsion who had scintiscans and adequate clinical follow-up were analyzed retrospectively. The scintiscans diagnosed 12/13 cases of surgically proven missed torsion and 3/3 cases of surgically proven acute complete torsion. The scintiscans successfully distinguished all 35 cases of epididymo-orchitis, 14 cases of torsion of the appendix testes and 8 other miscellaneous conditions from testicular torsion. The incidence of testicular torsion in our patients undergoing scrotal scintigraphy was approximately 24%.

  17. Research on torsional friction behavior and fluid load support of PVA/HA composite hydrogel.

    Science.gov (United States)

    Chen, Kai; Zhang, Dekun; Yang, Xuehui; Cui, Xiaotong; Zhang, Xin; Wang, Qingliang

    2016-09-01

    Hydrogels have been extensively studied for use as synthetic articular cartilage. This study aimed to investigate (1) the torsional friction contact state and the transformation mechanism of PVA/HA composite hydrogel against CoCrMo femoral head and (2) effects of load and torsional angle on torsional friction behavior. The finite element method was used to study fluid load support of PVA/HA composite hydrogel. Results show fluid loss increases gradually of PVA/HA composite hydrogel with torsional friction time, leading to fluid load support decreases. The contact state changes from full slip state to stick-slip mixed state. As the load increases, friction coefficient and adhesion zone increase gradually. As the torsional angle increases, friction coefficient and slip trend of the contact interface increase, resulting in the increase of the slip zone and the reduction of the adhesion zone. Fluid loss increases of PVA/HA composite hydrogel as the load and the torsional angle increase, which causes the decrease of fluid load support and the increase of friction coefficient.

  18. Plant-based torsional actuator with memory

    Science.gov (United States)

    Plaza, Nayomi; Zelinka, Samuel L.; Stone, Don S.; Jakes, Joseph E.

    2013-07-01

    A bundle of a few loblolly pine (Pinus taeda) cells are moisture-activated torsional actuators that twist multiple revolutions per cm length in direct proportion to moisture content. The bundles generate 10 N m kg-1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-activated, shape memory twist effect. Over 70% of the twist in a wetted bundle can be locked-in by drying under constraint and then released by rewetting the bundle. Our results indicate that hemicelluloses dominate the shape fixity mechanism and lignin is primarily responsible for remembering the bundle’s original form. The bundles demonstrate proof of a high specific torque actuator with large angles of rotation and shape memory twist capabilities that can be used in microactuators, sensors, and energy harvesters.

  19. Lobar torsion after lung transplantation

    Directory of Open Access Journals (Sweden)

    Mong-Wei Lin

    2013-02-01

    Full Text Available Lobar torsion is a rare complication after lung transplantation. Here we report a case of right middle lobe (RML torsion after bilateral sequential lung transplantation (BLTx. This 30-year-old lady underwent BLTx for bronchiolitis obliterans due to paraneoplastic pemphigus. The right lower lobe of the donor lung was resected due to inflammatory change during procurement. The postoperative chest X-ray showed persisting RML infiltrates. Fever and leukocytosis were noted 1 week later. RML lobectomy was performed after the reconstructed chest computed tomography confirmed the diagnosis of RML torsion. Adult respiratory distress syndrome with unstable vital signs, refractory hypoxemia and respiratory acidosis occurred thereafter. After venoarterial extracorporeal membrane oxygenation support, the patient recovered slowly and was discharged 5 months after BLTx.

  20. Torsional Carbon Nanotube Artificial Muscles

    Science.gov (United States)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  1. Constraining Torsion with Gravity Probe B

    CERN Document Server

    Mao, Y; Guth, A H; Tegmark, M; Cabi, Serkan; Guth, Alan; Mao, Yi; Tegmark, Max

    2006-01-01

    It is well-entrenched folklore that 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. We give an explicit counterexample where a rotating body generates a torsion field in Weitzenbock spacetime with a Hayashi-Shirafuji Lagrangian. More generally, in the spirit of action=reaction, if a rotating mass like a planet can generate torsion, then a gyroscope should also feel torsion. Using symmetry arguments, we show that to lowest order, the torsion field around a uniformly rotating spherical mass is determined by seven dimensionless parameters. These parameters effectively generalize the PPN formalism and provide a concrete framework for further testing GR. We construct a parametrized Lagrangian that includes both standard torsion-free GR and Hayashi-Shira...

  2. Torsional Weyl-Dirac Electrodinamics

    CERN Document Server

    Israelit, Mark

    1998-01-01

    Issuing from a geometry with nonmetricity and torsion we build up a classical theory of gravitation and electromagnetism. The theory is coordinate covariant as well Weyl-gauge covariant. Massless and massive photons, intrinsic electr. and magn. currents exist in this framework. The field EQ-s and EQ-s of motion are derived from a geometrically based action. It is shown that the magn.-magn. interaction is transmitted by massive photons. A magn. charge (monopole) cannot be located together with an electr. one. In absence of torsion and in the Einstein gauge one obtains the Einstein-Maxwell theory.

  3. Uterine torsion in term pregnancy

    Directory of Open Access Journals (Sweden)

    Sparić Radmila

    2007-01-01

    Full Text Available Introduction Uterine torsion has been defined as a rotation of more than 45 degrees of the uterus around its long axis that occurs at the junction between the cervix and the corpus. The extent of the rotation is usually 180 degrees, although cases with torsion from 60 to 720 degrees have been reported. Aetiopathogenesis of this condition is still unclear. Establishing clinical diagnosis of this condition is difficult, but very important for reducing maternal and fetal morbidity and mortality. Clinical symptoms are either absent or nonspecific, and the diagnosis is usually made at laparotomy. Case outlineA 31-year old patient was admitted to the Institute of Gynecology and Obstetrics, Clinical Center of Serbia, Belgrade, as an emergency, seven days upon the established intrauterine fetal demise in the 40th gestation week. On uterine examination, the cervical length of 1.5 cm and dilatation of 3 cm were determined, as well as a palpable soft tissue formation, not resembling placenta praevia. Ultrasound examination confirmed fetal demise and exclusion of the presence of placenta praevia. The labor was completed by caesarean section. During surgery, uterine torsion of 180 degrees to the right was diagnosed. There was a stillborn male baby, and the cause of death was intrauterine asphyxia. A fibrosing and calcified accessory lobe 9x6x2.5 cm in size was observed on placental examination, which is a possible sign of initial gemellary pregnancy. Conclusion The clinical presentation of uterine torsion is variable and clinical examination and ultrasonographic scanning may be insufficient for diagnosis. The method of choice for establishing the diagnosis is magnetic resonance imaging. Once the diagnosis of uterine torsion in pregnancy is established, emergency laparotomy is indicated. Following caesarean delivery, it is necessary to surgically remove all the anatomical causes of torsion, and rotate the uterus back to its normal position. There are some

  4. Can Ocular Torsion be Measured Using the Slitlamp Biomicroscope?

    Directory of Open Access Journals (Sweden)

    Kothari Mihir

    2005-03-01

    Full Text Available PURPOSE: To evaluate and compare a stereo-biomicroscopic technique of ocular torsion measurement with fundus photographic technique. METHODS: This prospective masked observational study included 72 eyes of 36 consecutive subjects with normal ocular motility. The disc-foveal angle was measured by two masked investigators using a slitlamp stereo-biomicroscopic and fundus photographic technique. RESULTS: The mean age was 13.7 years (6 - 44 years, and 15 (41.6% were males. The average torsion using the slitlamp technique was 5.5 3.3o and 6.1 4.3o with fundus photographic technique. Clinical agreement between the two techniques for 5o and 6o torsion was 81% and 90% respectively. The average difference between the two techniques was 3.0 2.6o. The mean inter-ocular difference was 3.3 2.7o (SD, 2.77 and 5.5 4.6o using the slitlamp and fundus photographic technique respectively. The Pearson correlation coefficient (r2 was 0.5 CONCLUSION: The fundus photographic technique remains the gold standard test for the measurement of ocular torsion. The slitlamp biomicroscopic method can be useful where a fundus camera is unavailable. Further studies are required to test the repeatability of these tests.

  5. The odd side of torsion geometry

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    2014-01-01

    We introduce and study a notion of `Sasaki with torsion structure' (ST) as an odd-dimensional analogue of Kähler with torsion geometry (KT). These are normal almost contact metric manifolds that admit a unique compatible connection with 3-form torsion. Any odd-dimensional compact Lie group is sho...

  6. An Abnormal Vibrational Mode of Torsion Pendulum

    Institute of Scientific and Technical Information of China (English)

    赵亮; 涂英; 顾邦明; 胡忠坤; 罗俊

    2003-01-01

    In the experiment for the determination of the gravitational constant G, we found an abnormal vibrational mode of the torsion pendulum. The abnormal mode disappeared as a magnetic damper was introduced to the torsion pendulum system. Our experimental results also show that the magnetic damper can be used to suppress the high frequency vibrational noises to torsion pendulums effectively.

  7. On one-sided torsion pair

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Motivated by the concept of a torsion pair in a pre-triangulated category induced by Beligiannis and Reiten, the notion of a left (right) torsion pair in the left (right) triangulated category is introduced and investigated. We provide new connections between different aspects of torsion pairs in one-sided triangulated categories, pre-triangulated categories, stable categories and derived categories.

  8. Human tibial torsion - Morphometric assessment and clinical relevance

    Directory of Open Access Journals (Sweden)

    Swati Gandhi

    2014-02-01

    Full Text Available Background: Tibial torsion is an important anatomical parameter in clinical practice and displays variability among individuals. These variations are extremely significant in view of alignment guides such as those related to rotational landmarks of tibia in total knee arthroplasty. Further, precise knowledge and information pertaining to angle of tibial torsion also helps in correction of traumatic malunion or congenital maltorsion of tibia. Methods: The present study was carried out to determine the angle of tibial torsion in 100 adult dry tibia bones in the Department of Anatomy, Government Medical College, Amritsar. The study group comprised 50 males and 50 females with equal number of right- and left-sided bones. The measurements were meticulously recorded and the data were subjected to statistical analysis. The results were analyzed and discussed in the light of existing literature. Results: On the right side, it was found to be 29.84° ± 4.86°° (range = 22.00° -38.00° in males and 28.92° ± 5.10°° (range = 15.00°-38.00° in females. On the left side, it was found to be 28.00° ± 4.94°° (range = 20.00°-40.00°° in males and 28.12° ± 4.28°° (range = 20.00°-37.00°° in females. Conclusion: The present study is an endeavor to provide baseline data with reference to the angle of tibial torsion in the Indian population. The results of the study assume special importance in view of the technical advancements in reconstructive surgical procedures in orthopedic practice.

  9. [Testicular torsion: A case report].

    Science.gov (United States)

    García-Fernández, Gustavo; Bravo-Hernández, Alberto; Bautista-Cruz, Raúl

    2016-07-13

    The acute scrotum is an emergency. Testicular torsion represents approximately 25% of the causes. The annual incidence of testicular torsion is approximately 1/4,000 persons under 25 years, with highest prevalence between 12 and 18 years old. It usually occurs without apparent cause, but it has been associated with anatomical, traumatic, and environmental factors, among others. A male 15 year-old male, with no history of importance, was seen in the Emergency Department, presenting with a sudden and continuous pain in the left testicle. It was accompanied by a pain that radiated to the abdomen and left inguinal area, with nausea and vomiting of more than 12h onset. Doppler ultrasound showed changes suggestive of testicular torsion. Surgery was performed that showed findings of a necrotic left testicle with rotation of the spermatic cord of 360°. A left orchiectomy was performed. Testicular torsion should always be considered one of the leading causes of acute scrotal pain. Delays in diagnosis should be avoided as this is directly related to the percentage of testicular salvage or loss. Copyright © 2016 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

  10. Torsion Gravity for Dirac Fields

    CERN Document Server

    Fabbri, Luca

    2016-01-01

    In this article we will take into account the most complete back-ground with torsion and curvature, providing the most exhaustive coupling for the Dirac field: we will discuss the integrability of the interaction of the matter field and the reduction of the matter field equations.

  11. Torsional inertia moment of beam element with complex section analysis based on FEM

    Institute of Scientific and Technical Information of China (English)

    Zhao An; Huang Jun; Lu Jianming

    2012-01-01

    Currently, for the analysis of complex bridge based on beam element, the calculation of cross-section torsional inertia moment is still an unresolved technical problem. Most current calculation of section torsional inertia moment is an approximate analytic method for two-dimensional cross-section, which is not fully consistent with the actual situation, and do not consider the effects of diaphragm in bridge. In order to analyze accurately cable-stayed bridge, suspension bridge and other complex bridge structures based on beam element, the calculation method of section torsional inertia moment based on finite element method (FEM) is invented in this paper. Firstly, setting up local cantilever fine model with solid element or shell element and applying torsion on the end of cantilever. Secondly, calculating the torsion angle of cantilever by FEM method and then the torsional moment through equivalent beam method. Finally, the examples of the section torsional moment calculation of concrete model with solid element with diaphragm and steel girder box model with shell element with diaphragm are used to verify the calculation method, which is applied to the suspension bridge design and construction control special software SBNA developed by Research Institute of Highway Ministry of Transport. Taizhou Bridge under construction is one of the examples.

  12. The torsional and rotation-torsion spectra of CD2HOH

    Science.gov (United States)

    Ndao, M.; Kwabia Tchana, F.; Coudert, L. H.; Motiyenko, R. A.; Margulès, L.; Barros, J.; Manceron, L.; Roy, P.

    2016-08-01

    The torsional and rotation-torsion spectra of the doubly deuterated species of methanol CD2HOH have been analyzed using submillimeter wave, terahertz, and far infrared spectra. 101 torsional subbands, with subband centers ranging from 2.3 to 626 cm-1, were assigned. Analysis of these yielded kinetic energy and hindering potential parameters of the torsional Hamiltonian describing the large amplitude internal rotation of the CD2H methyl group with respect to the hydroxyl group. 3271 rotation and rotation-torsion transitions, involving the 24 torsional levels up to e1 with 3 ⩽ K ⩽ 10 , were assigned and fitted approximating the rotational energy of each torsional level with a Taylor-type expansion in J (J + 1) . The rotational structure of 48 torsional subbands involving torsional levels higher than e1 has also been analyzed. In most cases, only the Q branch could be observed and assigned.

  13. MR evaluation of femoral neck version and tibial torsion

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, James Karl; Dwek, Jerry R. [University of California, San Diego, Children' s Hospital and Health Center, Department of Radiology, San Diego, CA (United States); Pring, Maya E. [Rady Children' s Hospital, Department of Pediatric Orthopedic Surgery, San Diego, CA (United States)

    2012-01-15

    Abnormalities of femoral neck version have been associated with a number of hip abnormalities in children, including slipped capital femoral epiphysis, proximal femoral focal deficiency, coxa vara, a deep acetabulum and, rarely, developmental dysplasia of the hip. Orthopedic surgeons also are interested in quantifying the femoral neck anteversion or retroversion in children especially to plan derotational osteotomies. Historically, the angle of femoral version and tibial torsion has been measured with the use of radiography and later by CT. Both methods carry with them the risks associated with ionizing radiation. Techniques that utilize MR are used less often because of the associated lengthy imaging times. This article describes a technique using MRI to determine femoral neck version and tibial torsion with total scan times of approximately 10 min. (orig.)

  14. TORSION OF THE VERMIFORM APPENDIX: A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Dr. Imtiaz Wani

    2009-07-01

    Full Text Available Torsion of the vermiform appendix is a rare condition with few cases reported in the literature. Various factors predispose to torsion. Various factors predispose to torsion. We report a case of primary torsion of the vermiform appendix. The clinical presentation was indistinguishable from acute appendicitis and the diagnosis was made at operation. Appendix was preileal in position and the direction of torsion was anticlockwise. There was intrinsic torsion with no obvious factor for torsion identified. Appendectomy was performed.

  15. Geometric Torsion in Adolescent Idiopathic Scoliosis: A Surgical Outcomes Study of Lenke Type 1 Patients.

    Science.gov (United States)

    Shen, Jesse; Kadoury, Samuel; Labelle, Hubert; Parent, Stefan

    2016-12-15

    Consecutive case series analysis. To evaluate the surgical outcomes of patients with thoracic adolescent idiopathic scoliosis (AIS) in relation to different degrees of geometric torsion. AIS is a three-dimensional (3D) deformity of the spine. A 3D classification of AIS, however, remains elusive because there is no widely accepted 3D parameter in the clinical practice. Recently, a new method of estimating geometric torsion has been proposed and detected two potential new 3D subgroups based on geometric torsion values. This is an analysis of 93 patients with Lenke type-1 deformity from our institution. 3D reconstructions were obtained using biplanar radiographs both pre- and postoperatively. Geometric torsion was computed using a novel technique by approximating local arc lengths at the neutral vertebra in the thoracolumbar segment. An inter- and intragroup statistical analysis was performed to compare clinical indices of patients with different torsion values. A qualitative assessment was also performed on each patient by two senior staff surgeons. Statistically significant differences were observed in clinical indices between high (2.85 mm) and low torsion (0.83 mm) Lenke type 1 subgroups. Preoperatively, the high torsion group showed higher Cobb angle values in the thoracic segment (71.18° vs. 63.74°), as well as higher angulation in the thoracolumbar plane of maximum deformity (67.79° vs. 53.30°). Postoperatively, a statistically significant difference was found in the orientation of the plane of maximum deformity in the thoracolumbar segment between the high and low torsion groups (47.95° vs. 30.03°). Results from the qualitative evaluation of surgical results showed different results between the two staff surgeons. These results suggest a link between preoperative torsion values and surgical outcomes within Lenke type 1 deformities. These results will need to be validated by an independent group, as it is a single-center study. 4.

  16. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough inv...... investigation of the intrinsic torsion of such structures; in addition to the construction of harmonic structures, this analysis leads to explicit Lie group examples with invariant intrinsic torsion.......We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough...

  17. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    2015-01-01

    We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2) Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We...... present a thorough investigation of the intrinsic torsion of such structures, leading to the construction of explicit Lie group examples with invariant intrinsic torsion.......We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2) Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We...

  18. Relative entropy and torsion coupling

    Science.gov (United States)

    Ning, Bo; Lin, Feng-Li

    2016-12-01

    We evaluate the relative entropy on a ball region near the UV fixed point of a holographic conformal field theory deformed by a fermionic operator of nonzero vacuum expectation value. The positivity of the relative entropy considered here is implied by the expected monotonicity of the decrease of quantum entanglement under the renormalization group flow. The calculations are done in the perturbative framework of Einstein-Cartan gravity in four-dimensional asymptotic anti-de Sitter space with a postulated standard bilinear coupling between the axial fermion current and torsion. By requiring positivity of relative entropy, our result yields a constraint on axial current-torsion coupling, fermion mass, and equation of state.

  19. Torsional Weyl-Dirac Electrodinamics

    OpenAIRE

    Israelit, Mark

    2007-01-01

    Issuing from a geometry with nonmetricity and torsion we build up a classical theory of gravitation and electromagnetism. The theory is coordinate covariant as well Weyl-gauge covariant. Massless and massive photons, intrinsic electr. and magn. currents exist in this framework. The field EQ-s and EQ-s of motion are derived from a geometrically based action. It is shown that the magn.-magn. interaction is transmitted by massive photons. A magn. charge (monopole) cannot be located together with...

  20. Torsions of 3-dimensional manifolds

    CERN Document Server

    Wurzbacher, T

    2002-01-01

    From the reviews: "This is an excellent exposition about abelian Reidemeister torsions for three-manifolds." ―Zentralblatt Math "This monograph contains a wealth of information many topologists will find very handy. …Many of the new points of view pioneered by Turaev are gradually becoming mainstream and are spreading beyond the pure topology world. This monograph is a timely and very useful addition to the scientific literature." ―Mathematical Reviews

  1. Topological design of torsional metamaterials

    Science.gov (United States)

    Vitelli, Vincenzo; Paulose, Jayson; Meeussen, Anne; Topological Mechanics Lab Team

    Frameworks - stiff elements with freely hinged joints - model the mechanics of a wide range of natural and artificial structures, including mechanical metamaterials with auxetic and topological properties. The unusual properties of the structure depend crucially on the balance between degrees of freedom associated with the nodes, and the constraints imposed upon them by the connecting elements. Whereas networks of featureless nodes connected by central-force springs have been well-studied, many real-world systems such as frictional granular packings, gear assemblies, and flexible beam meshes incorporate torsional degrees of freedom on the nodes, coupled together with transverse shear forces exerted by the connecting elements. We study the consequences of such torsional constraints on the mechanics of periodic isostatic networks as a foundation for mechanical metamaterials. We demonstrate the existence of soft modes of topological origin, that are protected against disorder or small perturbations of the structure analogously to their counterparts in electronic topological insulators. We have built a lattice of gears connected by rigid beams that provides a real-world demonstration of a torsional metamaterial with topological edge modes and mechanical Weyl modes.

  2. Les torsions sur testicules cryptorchides

    Science.gov (United States)

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

    2010-01-01

    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

  3. Dirac operators and Killing spinors with torsion; Dirac-Operatoren und Killing-Spinoren mit Torsion

    Energy Technology Data Exchange (ETDEWEB)

    Becker-Bender, Julia

    2012-12-17

    On a Riemannian spin manifold with parallel skew torsion, we use the twistor operator to obtain an eigenvalue estimate for the Dirac operator with torsion. We consider the equality case in dimensions four and six. In odd dimensions we describe Sasaki manifolds on which equality in the estimate is realized by Killing spinors with torsion. In dimension five we characterize all Killing spinors with torsion and obtain certain naturally reductive spaces as exceptional cases.

  4. Hidden torsion, 3-manifolds, and homology cobordism

    CERN Document Server

    Cha, Jae Choon

    2011-01-01

    This paper continues our exploration of homology cobordism of 3-manifolds using our recent results on Cheeger-Gromov rho-invariants associated to amenable representations. We introduce a new type of torsion in 3-manifold groups we call hidden torsion, and an algebraic approximation we call local hidden torsion. We construct infinitely many hyperbolic 3-manifolds which have local hidden torsion in the transfinite lower central subgroup. By realizing Cheeger-Gromov invariants over amenable groups, we show that our hyperbolic 3-manifolds are not pairwise homology cobordant, yet remain indistinguishable by any prior known homology cobordism invariants.

  5. Cosmological Background torsion limits from Lorentz violation

    CERN Document Server

    Garcia de Andrade, L C

    2001-01-01

    Cosmological limits on Lorentz invariance breaking in Chern-Simons $(3+1)-dimensional$ electrodynamics are used to place limits on torsion. Birefrigence phenomena is discussed by using extending the propagation equation to Riemann-Cartan spacetimes instead of treating it in purely Riemannian spaces. The parameter of Lorentz violation is shown to be proportional to the axial torsion vector which allows us to place a limit on cosmological background torsion from the Lorentz violation constraint which is given by $ 10^{-33} eV <|S^{\\mu}| < 10^{-32} eV$ where $|S^{\\mu}|$ is the axial torsion vector.

  6. Torsional characteristics of graphene nanoribbons encapsulated in single-walled carbon nanotubes

    Science.gov (United States)

    Fang, Te-Hua; Chang, Win-Jin; Feng, Yu-Lun; Lu, Deng-Maw

    2016-09-01

    Molecular dynamics (MD) simulations were performed to study the torsional characteristics of a graphene nanoribbon encapsulated in a single-walled carbon nanotube (GNR@SWCNT) with different chiralities at different temperatures. Based on the simulations, the relationship between the shear stress and the twist angle was obtained. The maximum shear stress increases with an increase in chirality. However, the corresponding twist angle decreases with increasing chirality. GNR@SWCNT withstands a smaller twist angle compared with a single SWCNT. In addition, the interaction force between the GNR and the SWCNT increases with increasing temperature. GNR@SWCNT at an elevated temperature is easier to break during torsion with a lower twist angle. The results are valuable for the design of nanocomposites composed of carbon nanotubes and graphene materials.

  7. Torsional Buckling and Writhing Dynamics of Elastic Cables and DNA

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, S; Perkins, N C; Lee, C L

    2003-02-14

    Marine cables under low tension and torsion on the sea floor can undergo a dynamic buckling process during which torsional strain energy is converted to bending strain energy. The resulting three-dimensional cable geometries can be highly contorted and include loops and tangles. Similar geometries are known to exist for supercoiled DNA and these also arise from the conversion of torsional strain energy to bending strain energy or, kinematically, a conversion of twist to writhe. A dynamic form of Kirchhoff rod theory is presented herein that captures these nonlinear dynamic processes. The resulting theory is discretized using the generalized-method for finite differencing in both space and time. The important kinematics of cross-section rotation are described using an incremental rotation ''vector'' as opposed to traditional Euler angles or Euler parameters. Numerical solutions are presented for an example system of a cable subjected to increasing twist at one end. The solutions show the dynamic evolution of the cable from an initially straight element, through a buckled element in the approximate form of a helix, and through the dynamic collapse of this helix through a looped form.

  8. Discrete Torsion and Symmetric Products

    CERN Document Server

    Dijkgraaf, R

    1999-01-01

    In this note we point out that a symmetric product orbifold CFT can be twisted by a unique nontrivial two-cocycle of the permutation group. This discrete torsion changes the spins and statistics of corresponding second-quantized string theory making it essentially ``supersymmetric.'' The long strings of even length become fermionic (or ghosts), those of odd length bosonic. The partition function and elliptic genus can be described by a sum over stringy spin structures. The usual cubic interaction vertex is odd and nilpotent, so this construction gives rise to a DLCQ string theory with a leading quartic interaction.

  9. Relative Entropy and Torsion Coupling

    CERN Document Server

    Lin, Feng-Li

    2016-01-01

    We evaluate the relative entropy on a ball region near the UV fixed point of a holographic conformal field theory deformed by a fermionic operator of nonzero vacuum expectation value. The positivity of the relative entropy considered here is implied by the expected monotonicity of decrease of quantum entanglement under RG flow. The calculations are done in the perturbative framework of Einstein-Cartan gravity in four-dimensional asymptotically anti-de Sitter space with a postulated standard bilinear coupling between axial fermion current and torsion. Our results however imply that the positivity of the relative entropy disfavors such a coupling.

  10. Effect of bilateral superior oblique split lengthening on torsion

    Directory of Open Access Journals (Sweden)

    Jitendra Jethani

    2015-01-01

    Full Text Available Introduction: Superior oblique split lengthening (SOSL is done for weakening of superior oblique. It corrects the superior oblique overaction (SOOA and A pattern. Its effect on the torsion of the eye is not known. We present our data on the effect of this particular procedure on torsion. Materials and Methods: We did a study of 16 patients (32 eyes who underwent bilateral SOSL and compared the disc foveal angle (DFA preoperatively and postoperatively. The split lengthening was done from 4 mm to 7 mm depending upon the overaction of superior oblique. Results: The mean age was 15.3 ± 8.4 years. Mean preoperative DFA in the right eye (RE was −3.9° and in the left eye (LE was −2.9°. Mean postoperative DFA in RE was 0.2° and in LE was 0.9°. The mean change in the DFA for RE was 4.1° ± 1.3° and for LE was 3.8° ± 1.2°. All the patients were aligned horizontally within 6 prism diopter and no pattern and no diplopia postoperatively. The A pattern was corrected in all the patient postsurgery. For each mm of surgery, an improvement of 0.8° was seen in the DFA. Conclusion: We report the effect of SOSL on torsion. The SOSL reduces intorsion postsurgery and is, therefore, a valuable procedure in SOOA where both pattern and in torsion needs to be corrected.

  11. Jet-cooled vibronic spectroscopy and asymmetric torsional potentials of phenylcyclopentene.

    Science.gov (United States)

    Newby, Josh J; Müller, Christian W; Liu, Ching-Ping; Zwier, Timothy S

    2009-10-01

    The ultraviolet spectroscopy of the S(1) laser-induced fluorescence (LIF) and single vibronic level fluorescence (SVLF). UV-UV hole-burning (UVHB) spectroscopy was used to determine that there is only one spectroscopically distinct conformer in the supersonic expansion. The excitation spectrum shows extensive vibronic structure extending to over 1000 cm(-1) above the electronic origin (34,646 cm(-1)). Much of the vibronic structure is similar to that of styrene and other singly substituted benzene derivatives, with Franck-Condon (FC) activity predominantly in substituent-sensitive benzene modes. Sizeable FC progressions were also found in the inter-ring torsion, reflecting a large displacement in the inter-ring angle upon electronic excitation. No evidence for FC activity in the ring-puckering coordinate is observed. The torsional potentials of the ground and excited states were determined from the experimental transition frequencies by fitting the calculated to the experimental torsional frequency spacings in an automated least-squares fitting procedure. The S(1) torsional potential is a symmetric single-well potential centered around a locally planar equilibrium geometry at a torsional angle of varphi = 0 degrees . The energy levels are reproduced by a cosine term potential function with torsional parameters V(2) = 3765 cm(-1) and V(4) = -183 cm(-1). The S(0) torsional potential possesses a twisted equilibrium geometry that is strongly asymmetric about varphi = 0 degrees due to the non-planarity of the cyclopentene ring. The best-fit potential parameters uses a sin/cos potential function (odd/even), with V = 948 cm(-1), V = -195 cm(-1), V = -162 cm(-1) and V = -268 cm(-1). The shape of the potentials are similar to those predicted by relaxed potential energy scans calculated at the DFT, CIS and TDDFT//CIS levels of theory. The change in the torsional angle varphi upon electronic excitation was determined to be approximately 15 degrees from fits of the

  12. Simultaneous acute appendicitis with right testicular torsion

    Directory of Open Access Journals (Sweden)

    Tanveer Akhtar

    2012-01-01

    Full Text Available We present a child with both acute appendicitis and torsion of the right testis presenting at the same time. Testicular torsion possibly occurring due to vomiting in acute appendicitis so far has not been reported in the literature.

  13. Type IIB orientifolds with discrete torsion

    CERN Document Server

    Karp, R L; Witten, Louis; Karp, Robert L; Witten, Louis

    2001-01-01

    We consider compact four-dimensional ${\\bf Z_N}\\times {\\bf Z_M}$ type IIB orientifolds, for certain values of $N$ and $M$. We allow the additional feature of discrete torsion and discuss the modification of the consistency conditions arising from tadpole cancellation. We point out the differences between the cases with and without discrete torsion.

  14. Torsional optomechanics of a levitated nonspherical nanoparticle

    CERN Document Server

    Hoang, Thai M; Ahn, Jonghoon; Bang, Jaehoon; Robicheaux, F; Yin, Zhang-Qi; Li, Tongcang

    2016-01-01

    An optically levitated nanoparticle in vacuum is a paradigm optomechanical system for sensing and studying macroscopic quantum mechanics. While its center-of-mass motion has been investigated intensively, its torsional vibration has only been studied theoretically in limited cases. Here we report the first experimental observation of the torsional vibration of an optically levitated nonspherical nanoparticle in vacuum. We achieve this by utilizing the coupling between the spin angular momentum of photons and the torsional vibration of a nonspherical nanoparticle whose polarizability is a tensor. The torsional vibration frequency can be one order of magnitude higher than its center-of-mass motion frequency, which is promising for ground state cooling. With an ellipsoidal model, we propose a simple yet novel scheme to achieve ground state cooling of its torsional vibration with a linearly-polarized Gaussian cavity mode. A levitated nonspherical nanoparticle in vacuum will also be an ultrasensitive nanoscale tor...

  15. Optically probing torsional superelasticity in spider silks

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-11

    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.

  16. Optically probing torsional superelasticity in spider silks

    Science.gov (United States)

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

    2013-11-01

    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.

  17. Statefinder diagnostic in a torsion cosmology

    CERN Document Server

    Li, Xin-zhou; Xi, Ping

    2009-01-01

    We apply the statefinder diagnostic to the torsion cosmology, in which an accounting for the accelerated universe is considered in term of a Riemann-Cartan geometry: dynamic scalar torsion. We find that there are some typical characteristic of the evolution of statefinder parameters for the torsion cosmology that can be distinguished from the other cosmological models. Furthermore, we also show that statefinder diagnostic has a direct bearing on the critical points. The statefinder diagnostic divides the torsion parameter $a_1$ into differential ranges, which is in keeping with the requirement of dynamical analysis. In addition, we fit the scalar torsion model to ESSENCE supernovae data and give the best fit values of the model parameters.

  18. Electrothermally-Actuated Micromirrors with Bimorph Actuators—Bending-Type and Torsion-Type

    Directory of Open Access Journals (Sweden)

    Cheng-Hua Tsai

    2015-06-01

    Full Text Available Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA. A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively.

  19. Torsion and antero-posterior bending in the in vivo human tibia loading regimes during walking and running.

    Science.gov (United States)

    Yang, Peng-Fei; Sanno, Maximilian; Ganse, Bergita; Koy, Timmo; Brüggemann, Gert-Peter; Müller, Lars Peter; Rittweger, Jörn

    2014-01-01

    Bending, in addition to compression, is recognized to be a common loading pattern in long bones in animals. However, due to the technical difficulty of measuring bone deformation in humans, our current understanding of bone loading patterns in humans is very limited. In the present study, we hypothesized that bending and torsion are important loading regimes in the human tibia. In vivo tibia segment deformation in humans was assessed during walking and running utilizing a novel optical approach. Results suggest that the proximal tibia primarily bends to the posterior (bending angle: 0.15°-1.30°) and medial aspect (bending angle: 0.38°-0.90°) and that it twists externally (torsion angle: 0.67°-1.66°) in relation to the distal tibia during the stance phase of overground walking at a speed between 2.5 and 6.1 km/h. Peak posterior bending and peak torsion occurred during the first and second half of stance phase, respectively. The peak-to-peak antero-posterior (AP) bending angles increased linearly with vertical ground reaction force and speed. Similarly, peak-to-peak torsion angles increased with the vertical free moment in four of the five test subjects and with the speed in three of the test subjects. There was no correlation between peak-to-peak medio-lateral (ML) bending angles and ground reaction force or speed. On the treadmill, peak-to-peak AP bending angles increased with walking and running speed, but peak-to-peak torsion angles and peak-to-peak ML bending angles remained constant during walking. Peak-to-peak AP bending angle during treadmill running was speed-dependent and larger than that observed during walking. In contrast, peak-to-peak tibia torsion angle was smaller during treadmill running than during walking. To conclude, bending and torsion of substantial magnitude were observed in the human tibia during walking and running. A systematic distribution of peak amplitude was found during the first and second parts of the stance phase.

  20. Effects of torsional disorder and position isomerism on two-photon absorption properties of polar chromophore dimers

    Science.gov (United States)

    Jia, Hai-Hong; Zhao, Ke; Wu, Xiang-Lian

    2014-09-01

    Two-photon absorption properties of a push-pull molecule and its covalent dimers have been studied by density functional response theory in combination with polarizable continuum model. A set of constrained geometries with different torsional angles are optimized and used to calculate two-photon absorption spectra. It is found that the torsional disorder could possibly produce the experimental two-photon absorption additive behavior. We have also designed a series of covalent dimers and investigated the effects of position isomerism. Our results suggest that the cooperative two-photon absorption enhancement can be achieved when the subunits are substituted in closer proximity and have larger interchromophore angle.

  1. Theoretical and Experimental Analysis of Torsional and Bending Effect on Four Cylinders Engine Crankshafts by Using Finite Element Approach

    Directory of Open Access Journals (Sweden)

    Prof. R. G. Desavale , A. M. Patil

    2013-10-01

    Full Text Available The problem of torsional vibration of the crankshaft of high-speed diesel engine has become critical with increase in excitation forces. This results in high torsional vibration amplitudes and hence high stresses the paper aims at complete FEM analysis of a crankshaft for torsional and bending vibrations, identification of stresses. It is analyzed for natural frequency, rigid body mode shape by ANSYS and Holzer method. The complete simulation of actual boundary conditions is done for journal bearing support, inertia lumping for reciprocating parts and bearing stiffness. Customized code is developed in ANSYS-Macros, which will convert user input Pressure-Crank angle variation to excitation forces for various orders through FFT. The dynamic responses obtained for displacement and stresses. Finally all results are combined to obtain the variation of Fillet Stress as a function of engine speed and harmonic orders. The critical dynamic response is compared with results obtained experimentally for torsional amplitudes.

  2. The Torsion of Spinor Connections and Related Structures

    Directory of Open Access Journals (Sweden)

    Frank Klinker

    2006-11-01

    Full Text Available In this text we introduce the torsion of spinor connections. In terms of the torsion we give conditions on a spinor connection to produce Killing vector fields. We relate the Bianchi type identities for the torsion of spinor connections with Jacobi identities for vector fields on supermanifolds. Furthermore, we discuss applications of this notion of torsion.

  3. Random torsional vibration in automobile transmissions

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The action of a road profile to the torsional vibrations in automobile transmissions is studied. The model to calculate the random torsional vibrations in the transmissions is proposed and the values of the model parameters are determined by both computation and experiment. Furthermore, the dynamic characteristics and the responses of automobile transmissions to the random excitation of road profile are calculated. The results of road experiment demonstrate that the theoretic analyses and the calculation are correct, which imply that the low frequency torsional vibrations in automobile transmissions are caused by the random excitation of a road profile.

  4. Left-sided omental torsion: CT appearance

    Energy Technology Data Exchange (ETDEWEB)

    Aoun, N.; Haddad-Zebouni, S.; Slaba, S.; Ghossain, M. [Hotel-Dieu de France Hospital, Beirut (Lebanon). Dept. of Radiology; Noun, R. [Hotel-Dieu de France Hospital, Beirut (Lebanon). Dept. of General Surgery

    2001-01-01

    A 34-year-old male presented with exquisite left flank pain. Computed tomography showed a hyperdense vascular structure surrounded by whirling linear streaks situated in the greater omentum under the splenic flexure of the colon. Omental stranding extended caudally into the pelvis where part of the inflamed omentum entered a left inguinal hernia sac. Surgery revealed left-sided torsion of the greater omentum. Left-sided omental torsion is infrequent and pre-operative diagnosis is rarely established. The CT findings of an omental fatty mass with a whirling pattern is characteristic of omental torsion. Preoperative diagnosis is important because conservative management has been suggested. (orig.)

  5. Aberrant femoral torsion presenting with frog-leg squatting mimicking gluteal muscle contracture.

    Science.gov (United States)

    Chiang, Chia-Ling; Tsai, Meng-Yuan; Chang, Wei-Ning; Chen, Clement Kuen-Huang

    2012-04-01

    Patients with frog-leg squatting have restricted internal rotation and adduction of the affected hips during sitting or squatting. In the surgical literature, the cause generally has been presumed to arise from and be pathognomonic for gluteal muscle contracture. However, we have encountered patients with frog-leg squatting but without gluteal muscle contracture. We therefore raised the following questions: What are the imaging features of patients with frog-leg squatting? Do conditions other than gluteal muscle contracture manifest frog-leg squatting? We retrospectively reviewed the MR images of 67 patients presenting with frog-leg squatting from April 1998 to July 2010. There were four females and 63 males; their mean age was 22.2 years (range, 4-50 years). During MRI readout, we observed aberrant axes of some femoral necks and obtained additional CT to measure femoral torsion angles in 59 of the 67 patients. MR images of 27 (40%) patients had signs of gluteal muscle contracture. Twenty-two (33%) patients (40 femora) had aberrant femoral torsion, including diminished anteversion (range, 6°-0°; average, 3.9°) in 11 femora of eight patients and femoral retroversion (range, muscle contracture or aberrant femoral torsion. The observation of aberrant femoral torsion was not anticipated before imaging studies. In addition to gluteal muscle contracture, aberrant femoral torsion can be a cause of frog-leg squatting. Level II, diagnostic study. See the guidelines for Authors for a complete description of levels of evidence.

  6. Influence of temperature changes on torsional rigidity and damping coefficient of rubber torsional vibration damper

    OpenAIRE

    Wojciech HOMIK

    2011-01-01

    The short explanation of usefulness of rubber torsional dampers in crankshaft in multi-cylinder engines is presented. The description of the construction and operation of rubber torsional damper is also included. In the rubber torsional damper, the damping is achieved as the effect of internal friction resulting from the deformation of the rubber material. This deformation appears while the internal rubber elasticity is overloaded. Both the physical and mechanical rubber properties depend on ...

  7. Analytic torsion versus Reidemeister torsion on hyperbolic 3-manifolds with cusps

    CERN Document Server

    Pfaff, Jonathan

    2012-01-01

    For a non-compact hyperbolic 3-manifold with cusps we prove an explicit formula that relates the regularized analytic torsion associated to the even symmetric powers of the standard representation of SL_2(C) to the corresponding Reidemeister torsion. Our proof rests on an expression of the analytic torsion in terms of special values of Ruelle zeta functions as well as on recent work of Pere Menal-Ferrer and Joan Porti.

  8. Influence of temperature changes on torsional rigidity and damping coefficient of rubber torsional vibration damper

    Directory of Open Access Journals (Sweden)

    Wojciech HOMIK

    2011-01-01

    Full Text Available The short explanation of usefulness of rubber torsional dampers in crankshaft in multi-cylinder engines is presented. The description of the construction and operation of rubber torsional damper is also included. In the rubber torsional damper, the damping is achieved as the effect of internal friction resulting from the deformation of the rubber material. This deformation appears while the internal rubber elasticity is overloaded. Both the physical and mechanical rubber properties depend on temperature change. In cooperation with rubber dampers manufacturer the experimental investigations are made in order to establish the influence of temperature change on torsional stiffness and damping.

  9. Torsional Oscillation Characteristics of Rotary Shafts Based on Torsion and Bending Coupled Vibration

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The torsional oscillation characteristics on the bending and torsion coupled vibration of rotary shaft system were investigated using the elasto-dynamic theory and other mathematic methods, such as difference approach, Fourier transform, and wavelet transform. It is concluded that mass eccentricity and other exciting modalities affect the bending and torsion coupled vibration of rotary shafts. Torsional vibration caused by bending vibration features linearity along with the change of amplitude of bending vibration. Meanwhile, energy spectrum concentrates on high frequency area with the wavelet analysis.

  10. Dark Energy: Is It of Torsion Origin?

    CERN Document Server

    Wanas, M I

    2010-01-01

    {\\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.

  11. Torsion and Supersymmetry in Omega-background

    CERN Document Server

    Ito, Katsushi; Sasaki, Shin

    2012-01-01

    We study the dimensional reduction of ten-dimensional super Yang-Mills theory in curved backgrounds with torsion. We examine the parallel spinor conditions and the constraints for the torsion parameters which preserve supersymmetry and gauge symmetry in four dimensions. In particular we examine the ten-dimensional Omega-background with the torsion which is identified with the R-symmetry Wilson line gauge fields. After the dimensional reduction, we obtain the Omega-deformed N=4 super Yang-Mills theory. Solving the parallel spinor conditions and the torsion constraints, we classify the deformed supersymmetry associated with the topological twist of N=4 supersymmetry. We also study deformed supersymmetries in the Nekrasov-Shatashvili limit.

  12. Torsional fluctuations in columnar DNA assemblies

    CERN Document Server

    Lee, D J

    2005-01-01

    In columnar assemblies of helical bio-molecules the azimuthal degrees of freedom, i.e. rotations about the long axes of molecules, may be important in determining the structure of the assemblies especially when the interaction energy between neighbouring molecules explicitly depends on their relative azimuthal orientations. For DNA this leads to a rich variety of mesophases for columnar assemblies, each categorized by a specific azimuthal ordering. In a preceding paper [A. Wynveen, D. J. Lee, and A. A. Kornyshev, Eur. Phys. J. E, 16, 303 (2005)] a statistical mechanical theory was developed for the assemblies of torsionally rigid molecues in order to determine how thermal fluctuations influence the structure of these mesophases. Here we extend this theory by including torsional fluctuations of the molecules, where a DNA molecule may twist about its long axis at the cost of torsional elastic energy. Comparing this with the previous study, we find that inclusion of torsional fluctuations further increases the d...

  13. Polyorchidism with presumed contralateral intrauterine testicular torsion

    Directory of Open Access Journals (Sweden)

    B.M. Leodoro

    2014-01-01

    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.

  14. Spin-torsion in Chaotic Inflation

    CERN Document Server

    Garcia de Andrade, L C

    1999-01-01

    The role of spin-torsion coupling to gravity is analyzed in the context of a model of chaotic inflation. The system of equations constructed from the Einstein-Cartan and inflaton field equations are studied and it is shown that spin-torsion interactions are effective only at the very first e-folds of inflation, becoming quickly negligible and, therefore, not affecting the standard inflationary scenario nor the density perturbations spectrum predictions.

  15. Case report of primary omental torsion

    Directory of Open Access Journals (Sweden)

    Jaisingh Shinde

    2015-01-01

    Full Text Available Omental torsion is an uncommon diagnosis for an acute abdomen. We present a case of a 45-year-old obese male who presented with acute pain on the right side of the abdomen for 2 days. Ultrasonography and computed tomography abdomen suggested an omental torsion, which was confirmed on laparoscopy. The omental infarct was resected, and the patient is asymptomatic for the past 15 months.

  16. Torsion and geometrostasis in covariant superstrings

    Energy Technology Data Exchange (ETDEWEB)

    Zachos, C.

    1985-01-01

    The covariant action for freely propagating heterotic superstrings consists of a metric and a torsion term with a special relative strength. It is shown that the strength for which torsion flattens the underlying 10-dimensional superspace geometry is precisely that which yields free oscillators on the light cone. This is in complete analogy with the geometrostasis of two-dimensional sigma-models with Wess-Zumino interactions. 13 refs.

  17. Torsion of Wandering Gallbladder following Colonoscopy

    Directory of Open Access Journals (Sweden)

    Sean R. Warfe

    2013-01-01

    Full Text Available Torsion of the gallbladder is an uncommon condition that may present as an acute abdomen. Its preoperative diagnosis can often be challenging due to its variable presentation, with specific sonographic signs seen infrequently. We describe, to our knowledge, the first case of torsion of a wandering gallbladder following a colonoscopy in a 69-year-old female who presented with acute abdominal pain after procedure. This was discovered intraoperatively, and after a subsequent cholecystectomy, she had an uncomplicated recovery.

  18. Angular position of the cleat according to torsional parameters of the cyclist's lower limb.

    Science.gov (United States)

    Ramos-Ortega, Javier; Domínguez, Gabriel; Castillo, José Manuel; Fernández-Seguín, Lourdes; Munuera, Pedro V

    2014-05-01

    The aim of this work was to study the relationship of torsional and rotational parameters of the lower limb with a specific angular position of the cleat to establish whether these variables affect the adjustment of the cleat. Correlational study. Motion analysis laboratory. Thirty-seven male cyclists of high performance. The variables studied of the cyclist's lower limb were hip rotation (internal and external), tibial torsion angle, Q angle, and forefoot adductus angle. The cleat angle was measured through a photograph of the sole and with an Rx of this using the software AutoCAD 2008. The variables were photograph angle (photograph), the variable denominated cleat-tarsus minor angle, and a variable denominated cleat-second metatarsal angle (Rx). Analysis included the intraclass correlation coefficient for the reliability of the measurements, Student's t test performed on the dependent variables to compare side, and the multiple linear regression models were calculated using the software SPSS 15.0 for Windows. The Student's t test performed on the dependent variables to compare side showed no significant differences (P = 0.209 for the photograph angle, P = 0.735 for the cleat-tarsus minor angle, and P = 0.801 for the cleat-second metatarsal angle). Values of R and R2 for the photograph angle model were 0.303 and 0.092 (P = 0.08), the cleat/tarsus minor angle model were 0.683 and 0.466 (P rotation of the hips) + (0.220 × Q angle).

  19. Femoral Shaft Torsion in Injured and Uninjured Ballet Dancers and Its Association with Other Hip Measures: A Cross-sectional Study.

    Science.gov (United States)

    Hafiz, Eliza; Hiller, Claire E; Nicholson, Leslie L; Nightingale, Elizabeth J; Grimaldi, Alison; Refshauge, Kathryn M

    2016-03-01

    Low range femoral torsion, termed "lateral shaft torsion," has been associated with greater range of hip external rotation and turnout in dancers. It is also hypothesized that achieving greater turnout at the hip minimizes torsion at the knee, shank, ankle, and foot, and consequently reduces incidence of lower limb injuries. The primary aims of this study were to investigate: 1. differences in range of femoral shaft torsion between dancers with and without lower limb injuries; and 2. the relationship between femoral shaft torsion, hip external rotation range, and turnout. A secondary aim was to examine the relationship between femoral shaft torsion and other hip measures: hip strength, lower limb joint hypermobility, hip stability, and foot progression angle, as explanatory variables. Demographic, dance, and injury data were collected, along with physical measures of femoral shaft torsion, hip rotation range of motion, and turnout. Hip strength, control, lower limb hypermobility, and foot progression angle were also measured. Eighty female dancers, 50 with lower limb injury (20.7 ± 4.8 years of age) and 30 without lower limb injury (17.8 ± 4.1 years of age), participated in the study. There was no difference in range of femoral shaft torsion between the groups (p = 0.941). Femoral shaft torsion was weakly correlated with range of hip external rotation (r = -0.034, p = 0.384) and turnout (r = -0.066, p = 0.558). Injured dancers had a significantly longer training history than non-injured dancers (p = 0.001). It was concluded that femoral shaft torsion does not appear to be associated with the overall incidence of lower limb injury in dancers or to be a primary factor influencing extent of turnout in this population.

  20. Torsional oscillations of strange stars

    Directory of Open Access Journals (Sweden)

    Mannarelli Massimo

    2014-01-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2014-01-01

    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 [Formula: see text] at the signal frequency of 2 mHz, which contributes a [Formula: see text] uncertainty to the G value.

  2. Torsion-mediated interaction between adjacent genes.

    Directory of Open Access Journals (Sweden)

    Sam Meyer

    2014-09-01

    Full Text Available 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 (coregulation in eukaryotes.

  3. Ultimate Strength of Ship Hulls under Torsion

    DEFF Research Database (Denmark)

    Paik, Jeom Kee; Thayamballi, Anil K.; Pedersen, Preben Terndrup

    2001-01-01

    For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening deformations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength characte......For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening deformations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength...... characteristics of ships with large hatch openings. The primary aim of the present study is to investigate the ultimate strength characteristics of ship hulls with large hatch openings under torsion. Axial (warping) as well as shear stresses are normally developed for thin-walled beams with open cross sections...... analyses, it is shown that the influence of torsion induced warping stresses on the ultimate hull girder bending strength is small for ductile hull materials while torsion induced shear stresses will of course reduce the ship hull ultimate bending moment....

  4. Metric-torsion preheating: cosmic dynamo mechanism?

    CERN Document Server

    de Andrade, L C Garcia

    2014-01-01

    Earlier Bassett et al [Phys Rev D 63 (2001) 023506] investigated the amplification of large scale magnetic fields during preheating and inflation in several different models. They argued that in the presence of conductivity resonance effect is weakened. From a dynamo equation in spacetimes endowed with torsion recently derived by Garcia de Andrade [Phys Lett B 711: 143 (2012)] it is shown that a in a universe with pure torsion in Minkowski spacetime the cosmological magnetic field is enhanced by ohmic or non-conductivity effect, which shows that the metric-torsion effects is worth while of being studied. In this paper we investigated the metric-torsion preheating perturbation, which leads to the seed cosmological magnetic field in the universe with torsion is of the order of $B_{seed}\\sim{10^{-37}Gauss}$ which is several orders of magnitude weaker than the decoupling value obtained from pure metric preheating of $10^{-15}Gauss$. Despite of the weakness of the magnetic field this seed field may seed the galact...

  5. On the relationship between tibia torsional deformation and regional muscle contractions in habitual human exercises in vivo.

    Science.gov (United States)

    Yang, Peng-Fei; Kriechbaumer, Andreas; Albracht, Kirsten; Sanno, Maximilian; Ganse, Bergita; Koy, Timmo; Shang, Peng; Brüggemann, Gert-Peter; Müller, Lars Peter; Rittweger, Jörn

    2015-02-05

    The mechanical relationship between bone and muscle has been long recognized. However, it still remains unclear how muscles exactly load on bone. In this study, utilizing an optical segment tracking technique, the in vivo tibia loading regimes in terms of tibia segment deformation in humans were investigated during walking, forefoot and rear foot stair ascent and running and isometric plantar flexion. Results suggested that the proximal tibia primarily bends to the posterior aspect and twists to the external aspect with respect to the distal tibia. During walking, peak posterior bending and peak torsion occurred in the first half (22%) and second half (76%) of the stance phase, respectively. During stair ascent, two noticeable peaks of torsion were found with forefoot strike (38% and 82% of stance phase), but only one peak of torsion was found with rear foot strike (78% of stance phase). The torsional deformation angle during both stair ascent and running was larger with forefoot strike than rear foot strike. During isometric plantar flexion, the tibia deformation regimes were characterized more by torsion (maximum 1.35°) than bending (maximum 0.52°). To conclude, bending and torsion predominated the tibia loading regimes during the investigated activities. Tibia torsional deformation is closely related to calf muscle contractions, which further confirm the notion of the muscle-bone mechanical link and shift the focus from loading magnitude to loading regimes in bone mechanobiology. It thus is speculated that torsion is another, yet under-rated factor, besides the compression and tension, to drive long bone mechano-adaptation.

  6. Collective effects of torsion in FtsZ filaments

    Science.gov (United States)

    González de Prado Salas, Pablo; Tarazona, Pedro

    2016-04-01

    Recent evidence points to the presence of torsion in FtsZ bonds. In addition, experiments with FtsZ mutants on surfaces resulted in new aggregates that cannot be explained by older models for FtsZ dynamics. We use an interaction model for FtsZ derived from molecular dynamics simulations and expand a fine-grained lattice model used to describe FtsZ aggregates on a surface. This new model includes different anchoring angles for the monomers and allows bond twist, two ingredients that oppose each other resulting in a more dynamic and interesting system. We study the role and importance of these conflicting elements and how the aggregates are characterized by the different interaction parameters.

  7. Effect of collagen fibre orientation on intervertebral disc torsion mechanics.

    Science.gov (United States)

    Yang, Bo; O'Connell, Grace D

    2017-07-21

    The intervertebral disc is a complex fibro-cartilaginous material, consisting of a pressurized nucleus pulposus surrounded by the annulus fibrosus, which has an angle-ply structure. Disc injury and degeneration are noted by significant changes in tissue structure and function, which significantly alters stress distribution and disc joint stiffness. Differences in fibre orientation are thought to contribute to changes in disc torsion mechanics. Therefore, the objective of this study was to evaluate the effect of collagen fibre orientation on internal disc mechanics under compression combined with axial rotation. We developed and validated a finite element model (FEM) to delineate changes in disc mechanics due to fibre orientation from differences in material properties. FEM simulations were performed with fibres oriented at [Formula: see text] throughout the disc (uniform by region and fibre layer). The initial model was validated by published experimental results for two load conditions, including [Formula: see text] axial compression and [Formula: see text] axial rotation. Once validated, fibre orientation was rotated by [Formula: see text] or [Formula: see text] towards the horizontal plane, resulting in a decrease in disc joint torsional stiffness. Furthermore, we observed that axial rotation caused a sinusoidal change in disc height and radial bulge, which may be beneficial for nutrient transport. In conclusion, including anatomically relevant fibre angles in disc joint FEMs is important for understanding stress distribution throughout the disc and will be important for understanding potential causes for disc injury. Future models will include regional differences in fibre orientation to better represent the fibre architecture of the native disc.

  8. Anisotropy of torsional rigidity of sheet polymer composite materials

    Science.gov (United States)

    Startsev, O. V.; Kovalenko, A. A.; Nasonov, A. D.

    1999-05-01

    Wide application of polymer composite materials (PCM) in modern technology calls for detailed evaluation of their stress-strain properties in a broad temperature range. To obtain such information, we use the dynamic mechanical analysis and with the help of a reverse torsion pendulum measure the dynamic torsional rigidity of PCM bars of rectangular cross section in the temperature range up to 600 K. It is found that the temperature dependences of the dynamic rigidity of the calculated values of dynamic shear moduli are governed by the percentage and properties of the binder and fibers, the layout of fibers, the phase interaction along interfaces, etc. The principles of dynamic mechanical spectrometry are used to substantiate and analyze the parameters of anisotropy by which the behavior of a composite can be described in the temperature range including the transition of the binder from the glassy into a highly elastic state. For this purpose, the values of dynamic rigidity are measured under low-amplitude vibrations of the PCM specimens with a fiber orientation angle from 0 to 90°. It is shown that for unidirectional composites the dependence between the dynamic rigidity and the fiber orientation angle is of extreme character. The value and position of the peak depend on the type of the binder and fibers and change with temperature. It is found that the anisotropy degree of PCM is dictated by the molecular mobility and significantly changes in the temperature range of transition of the binder and reinforcement from the glassy into a highly elastic state (in the case of SVM fibers). The possibility of evaluating the anisotropy of composites with other reinforcement schemes, in particular, of orthogonally reinforced PCMs, is shown.

  9. Active structures to reduce torsional vibrations

    Science.gov (United States)

    Matthias, M.; Schlote, D.; Atzrodt, H.

    2013-03-01

    This paper describes the development of different active measures to reduce torsional vibrations in power trains. The measures are based on concepts developed for active mounts to reduce the transmission of structure-borne sound. To show the potential of these active measures and investigate their mode of operation to influence torsional vibrations, numerical simulations of powertrains with different active measures were done. First experimental results from tests on an experimental (reduced size) power train were used to align the numerical models. The work was done within the project 'LOEWE-Zentrum AdRIA: Adaptronik - Research, Innovation, Application' funded by the German federal state of Hessen, and the Project AKTos: 'Active control of torsional vibrations by coupling elements' placed in the research Framework program 'Navigation and Maritime Technology for the 21st Century' funded by the German Federal Ministry of Economics and Technology.

  10. Torsional rigidity of submanifolds with controlled geometry

    DEFF Research Database (Denmark)

    Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente

    2009-01-01

    We prove explicit upper and lower bounds for the torsional rigidity of extrinsic domains of submanifolds ^m$ with controlled radial mean curvature in ambient Riemannian manifolds ^n$ with a pole $ and with sectional curvatures bounded from above and from below, respectively. These bounds are given...... in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped product model spaces. Our main results are obtained using methods from previously established isoperimetric inequalities, as found in e.g. [MP4] and [MP5]. As in [MP4] we also characterize the geometry...... of those situations in which the bounds for the torsional rigidity are actually attained and study the behavior at infinity of the so-called geometric average of the mean exit time for Brownian motion....

  11. Torsional wave propagation in solar tornadoes

    Science.gov (United States)

    Vasheghani Farahani, S.; Ghanbari, E.; Ghaffari, G.; Safari, H.

    2017-03-01

    Aims: We investigate the propagation of torsional waves in coronal structures together with their collimation effects in the context of magnetohydrodynamic (MHD) theory. The interplay of the equilibrium twist and rotation of the structure, e.g. jet or tornado, together with the density contrast of its internal and external media is studied to shed light on the nature of torsional waves. Methods: We consider a rotating magnetic cylinder embedded in a plasma with a straight magnetic field. This resembles a solar tornado. In order to express the dispersion relations and phase speeds of the axisymmetric magnetohydrodynamic waves, the second-order thin flux tube approximation is implemented for the internal medium and the ideal MHD equations are implemented for the external medium. Results: The explicit expressions for the phase speed of the torsional wave show the modification of the torsional wave speed due to the equilibrium twist, rotation, and density contrast of the tornado. The speeds could be either sub-Alfvénic or ultra-Alfvénic depending on whether the equilibrium twist or rotation is dominant. The equilibrium twist increases the phase speed while the equilibrium rotation decreases it. The good agreement between the explicit versions for the phase speed and that obtained numerically proves adequate for the robustness of the model and method. The density ratio of the internal and external media also play a significant role in the speed and dispersion. Conclusions: The dispersion of the torsional wave is an indication of the compressibility of the oscillations. When the cylinder is rotating or twisted, in contrast to when it only possesses a straight magnetic field, the torsional wave is a collective mode. In this case its phase speed is determined by the Alfvén waves inside and outside the tornado.

  12. Clinical variants of idiopathic torsion dystonia.

    Science.gov (United States)

    Fahn, S

    1989-06-01

    Some patients with dystonic movements and postures not known to be caused by environmental or degenerative disorders can be segregated from classical-appearing idiopathic torsion dystonia on the basis of distinctive clinical and pharmacologic features. Many of them should be considered within the family of dystonia, as clinical variants of idiopathic torsion dystonia, while others are better classified as being part of other families of dyskinesias. In the former group are paradoxical dystonia, myoclonic dystonia, diurnal dystonia, and dopa-responsive dystonia. The latter group consists of dystonic tics and the various entities comprising paroxysmal dystonia, namely kinesigenic, nonkinesigenic and hypnogenic dystonia.

  13. Ventricular torsional relation to ventricular fiber arrangement

    CERN Document Server

    Ranjbar, Saeed; Meybodi, Mahmood Emami

    2014-01-01

    Left ventricular torsion from helically oriented myofibers is a key parameter of cardiac performance. Physicians observing heart motion on echocardiograms, during cardiac catheterization, or in the operating room, are impressed by the twisting or rotary motion of the left ventricle during systole. Conceptually, the heart has been treated as a pressure chamber. The rotary or torsional deformation has been poorly understood by basic scientists and has lacked clinical relevance. The aim of this paper attempts to discuss about this question: Is ventricular twisting related to ventricular fiber arrangement? That is dependent to an assumed model of the left ventricular structure.

  14. Torsional Performance of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Branner, Kim; Berring, Peter; Berggreen, Christian

    2007-01-01

    The present work investigates how well different finite element modeling techniques can predict bending and torsion behavior of a wind turbine blade. Two shell models are investigated. One model has element offsets and the other has the elements at the mid-thickness surfaces of the model. The last...... two models investigated use a combination of shell and solid elements. The results from the numerical investigations are compared with measurements from testing of a section of a full-scale wind turbine blade. It is found that only the combined shell/solid models give reliable results in torsion. Both...

  15. Torsion Part of ℤ-module

    Directory of Open Access Journals (Sweden)

    Futa Yuichi

    2015-12-01

    Full Text Available In this article, we formalize in Mizar [7] the definition of “torsion part” of ℤ-module and its properties. We show ℤ-module generated by the field of rational numbers as an example of torsion-free non free ℤ-modules. We also formalize the rank-nullity theorem over finite-rank free ℤ-modules (previously formalized in [1]. ℤ-module is necessary for lattice problems, LLL (Lenstra, Lenstra and Lovász base reduction algorithm [23] and cryptographic systems with lattices [24].

  16. Torsion theories of pseudo-regular S-systems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The concept of pseudo-regular S-system is introduced. A torsion theory τu = ( Us, Us) with its torsion class Us consisting of pseudo-regular S-systems is constructed. Its corresponding quasi-filter is completely described. A number of results on the relations between τu and two special torsion theories, the stable and Larnbek torsion theories, are obtained.

  17. Improved Angle Potentials for Coarse-Grained Molecular Dynamics Simulations

    NARCIS (Netherlands)

    Bulacu, Monica; Goga, Nicolae; Zhao, Wei; Rossi, Giulia; Monticelli, Luca; Periole, Xavier; Tieleman, D. Peter; Marrink, Siewert J.

    2013-01-01

    Potentials routinely used in atomistic molecular dynamics simulations are not always suitable for modeling systems at coarse-grained resolution. For example, in the calculation of traditional torsion angle potentials, numerical instability is often encountered in the case of very flexible molecules.

  18. Influence of the ultimate torsion on the geometry of dental implants.

    Science.gov (United States)

    Teixeira, Ana Beatriz V; Beja, Gabriela B S P; Shimano, Antônio Carlos; Macedo, Ana Paula; Oliscovicz, Nathalia Ferraz; Reis, Andréa C dos

    2013-01-01

    This study evaluated the profile of implants subjected to torsion test. Four types of implants (Conexão®) were analyzed: Master Porous (MP - external hexagon, cylindrical, double-porous surface implants; 11.5 X 3.75 mm), Master Screw (MS - external hexagon, cylindrical, machined implants; 11.5 X 3.75 mm), Conect Conic (CC - external hexagon, cylindrical, machined implants; 11.5 X 3.5 mm) and Master Conect AR (CA - internal hexagon, cylindrical, double-porous surface implants; 11.5 X 3.75 mm). The Nikon® model C profile projector was used for the analysis before and after torsion test with a Mackena® model MK-20XX digital torque meter. The measures analyzed in the profile of implants were: diameter and height of the platform, diameter of the screw/platform connection, angle of the screw/platform connection, external diameter, internal diameter, thread pitch, height and length of the thread. Statistical analysis was performed using ANOVA and Tukey test at 5% significance level. The torsion test caused a visible deformity on the external implant profile. There was a statistical difference among the implants before and after torsion (pstripping of CC. Thus, it was concluded that excessive or some unadvised torque by the manufacturer can lead to changes in different geometric measurements of implants.

  19. From speckle tracking echocardiography to torsion: research tool today, clinical practice tomorrow.

    Science.gov (United States)

    Huang, Stephen J; Orde, Sam

    2013-06-01

    Speckle tracking is the latest available technology in echocardiography. However, the technology is still mainly used as a research tool. The potential applications of speckle tracking are many, including cardiac synchronization, regional wall motion analysis, and in the areas of cardiac mechanic studies. This review presents the background theory of speckle tracking echocardiography (STE) and how this technology can be extended to velocity vector analysis, strain, and torsion measurements. The interpretations of these measurements are covered. We also present some potential applications in the critical care setting. Speckle tracking is almost always available in high-end ultrasound machines. The technology has been applied to velocity vector analysis, strain and strain rate measurements, and twist and torsion analysis. Torsion analysis and velocity vector analyses are impossible without using speckle tracking. Speckle tracking-derived strain is superior to tissue Doppler strain because it is angle-independent. A number of studies demonstrated that STE is useful in left and right heart assessments and can be used in assessing preload and afterload. Speckle tracking can be used to measure instantaneous myocardial contractility, strain, and left ventricular torsion. It is still a research tool at present, but shows the promise of being a clinical tool in the future.

  20. Effect of Compression with Oscillatory Torsion Processing on Structure and Properties of Cu

    Institute of Scientific and Technical Information of China (English)

    Kinga Rodak; Jacek Pawlicki

    2011-01-01

    The results presented in this study were concerned with microstructures and mechanical properties of poly- crystalline Cu subjected to plastic deformation by a compression with oscillatory torsion process. Different deformation parameters of the compression with oscillatory torsion process were adopted to study their effects on the microstructure and mechanical properties. The deformed microstructure was characterized quantitatively by electron backscattered diffraction (EBSD) and scanning transmission electron microscopy (STEM). Mechanical properties were determined on an MTS QTest/10 machine equipped with digital image correlation. From the experimental results, processes performed at high compression speed and high torsion frequency are recommended for refining the grain size. The size of structure elements, such as average grain size (D) and subgrain size (d), reached 0.42 μm and 0.30 μm, respectively, and the fraction of high angle boundaries was 35% when the sample was deformed at a torsion frequency f = 1.6 Hz and compression rate v= 0.04 mm/s. These deformation parameters led to an improvement in the strength properties. The material exhibited an ultimate tensile strength (UTS) of 434 MPa and a yield strength (YS) of 418 MPa. These values were about two times greater than those of the initial state.

  1. Light deflection with torsion effects caused by a spinning cosmic string

    Energy Technology Data Exchange (ETDEWEB)

    Jusufi, Kimet [State University of Tetovo, Physics Department, Tetovo (Macedonia, The Former Yugoslav Republic of)

    2016-06-15

    Using a new geometrical method introduced by Werner, we find the deflection angle in the weak limit approximation by a spinning cosmic string in the context of the Einstein-Cartan (EC) theory of gravity. We begin by adopting the String-Randers optical metric, then we apply the Gauss-Bonnet theorem to the optical geometry and derive the leading terms of the deflection angle in the equatorial plane. Calculation shows that light deflection is affected by the intrinsic spin of the cosmic string and torsion. (orig.)

  2. Light deflection with torsion effects caused by a spinning cosmic string

    Science.gov (United States)

    Jusufi, Kimet

    2016-06-01

    Using a new geometrical method introduced by Werner, we find the deflection angle in the weak limit approximation by a spinning cosmic string in the context of the Einstein-Cartan (EC) theory of gravity. We begin by adopting the String-Randers optical metric, then we apply the Gauss-Bonnet theorem to the optical geometry and derive the leading terms of the deflection angle in the equatorial plane. Calculation shows that light deflection is affected by the intrinsic spin of the cosmic string and torsion.

  3. Light Deflection with Torsion Effects Caused by a Spinning Cosmic String

    CERN Document Server

    Jusufi, Kimet

    2016-01-01

    Using a new geometrical method introduced by Werner, we find the deflection angle in the weak limit approximation by a spinning cosmic string in the context of the Einstein-Cartan (EC) theory of gravity. We begin by adopting the String-Randers optical metric, then we apply the Gauss-Bonnet theorem to the optical geometry and derive the leading terms of the deflection angle in the equatorial plane. Calculations shows that light deflection is affected by the intrinsic spin of the cosmic string and torsion.

  4. Thermoelastic Correction in the Torsion Pendulum Experiment

    Institute of Scientific and Technical Information of China (English)

    胡忠坤; 王雪黎; 罗俊

    2001-01-01

    The thermoelastic effect of the suspension fibre in the torsion pendulum experiment with magnetic damping was studied. The disagreement in the oscillation periods was reduced by one order of magnitude through monitoring the ambient temperature and thermoelastic correction. We also found that the period on uncertainty due to noise increases with the amplitude attenuation after thermoelastic correction.

  5. Torsion of the gallbladder: a case report

    Directory of Open Access Journals (Sweden)

    Ijaz Samia

    2008-07-01

    Full Text Available Abstract Introduction Torsion of the gallbladder is a rare condition that most commonly affects the elderly. Pre-operative diagnosis is the exception rather than the rule. Any delay in treatment can be fatal as the gallbladder may rupture, leading to biliary peritonitis. Case presentation We present the case of an 80-year-old woman who was admitted with right upper quadrant pain initially thought to be secondary to acute cholecystitis. Subsequent ultrasound and computed tomography scans of the abdomen revealed signs suggestive of acute cholecystitis but neither modality detected any gallstones. As the patient's symptoms failed to resolve on conservative management, she was taken to theatre for an open cholecystectomy. Intra-operatively, the gallbladder had undergone complete torsion and appeared gangrenous. A routine cholecystectomy followed and she recovered from the operation without incident. Conclusion It is rare to diagnose torsion of the gallbladder pre-operatively despite advances in diagnostic imaging. However, this differential diagnosis should be borne in mind particularly in the elderly patient, without proven gallstones, who fails to improve on conservative management. An emergency cholecystectomy is indicated in the event of diagnosing torsion of the gallbladder to avert the potentially lethal sequelae of biliary peritonitis.

  6. Test particle acceleration in torsional fan reconnection

    Science.gov (United States)

    Hosseinpour, M.

    2014-12-01

    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.

  7. Plant-based torsional actuator with memory

    Science.gov (United States)

    Nayomi Plaza; Samuel L. Zelinka; Don S. Stone; Joseph E. Jakes

    2013-01-01

    A bundle of a few loblolly pine (Pinus taeda) cells are moisture-activated torsional actuators that twist multiple revolutions per cm length in direct proportion to moisture content. The bundles generate 10 N m kg􀀀1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-...

  8. Symmetric products, permutation orbifolds and discrete torsion

    CERN Document Server

    Bántay, P

    2000-01-01

    Symmetric product orbifolds, i.e. permutation orbifolds of the full symmetric group S_{n} are considered by applying the general techniques of permutation orbifolds. Generating functions for various quantities, e.g. the torus partition functions and the Klein-bottle amplitudes are presented, as well as a simple expression for the discrete torsion coefficients.

  9. Torsional Vibration Analysis of an FR Driveline System

    Institute of Scientific and Technical Information of China (English)

    任少云; 朱正礼; 张建武

    2004-01-01

    Towing tractor drivelines are lightly damped non-linear systems. Interactions between components can cause dynamic behavors such as gear gap impact in gear transmissions, shuffle and clonk phenomena in driveline. The torsional vibration of driveline has an important effect on grand engineering vehicle vibration and noise. Through analyzing torsional vibration equations of driveline, torsional vibration model of driveline is developed by using Matlab/Simulink software, Shuffle and clonk phenomena are observed in torsional vibration. The modeling method of analysizing driveline torsional vibration can be used to research and improve similar engineering vehicle driveline behavors.

  10. Effects of torsional degree of freedom, geometric nonlinearity, and gravity on aeroelastic behavior of large-scale horizontal axis wind turbine blades under varying wind speed conditions

    DEFF Research Database (Denmark)

    Jeong, Min-Soo; Cha, Myung-Chan; Kim, Sang-Woo

    2014-01-01

    Modern horizontal axis wind turbine blades are long, slender, and flexible structures that can undergo considerable deformation, leading to blade failures (e.g., blade-tower collision). For this reason, it is important to estimate blade behaviors accurately when designing large-scale wind turbines....... In this study, a numerical analysis considering blade torsional degree of freedom, geometric nonlinearity, and gravity was utilized to examine the effects of these factors on the aeroelastic blade behavior of a large-scale horizontal axis wind turbine. The results predicted that flapwise deflection is mainly...... affected by the torsional degree of freedom, which causes the blade bending deflections to couple to torsional deformation, thereby varying the aerodynamic loads through changes in the effective angle of attack. Edgewise deflection and torsional deformation are mostly influenced by the periodic...

  11. Femoral torsion assessment with MRI in children: Should we use the bony or cartilaginous contours?

    Science.gov (United States)

    Rosskopf, Andrea B; Agten, Christoph A; Ramseier, Leonhard E; Pfirrmann, Christian W A; Buck, Florian M

    2017-07-01

    To assess whether the use of cartilaginous contours at the femoral condyles instead of bony contours significantly changes femoral torsion measurements in children. Femoral torsion was measured in 32 girls (mean age 10.1 years±2.3 standard deviation) and 42 boys (10.9 years±2.5) on axial magnetic resonance (MR) images by two independent readers (R1,R2). The femoral condyle angle was measured using each the cartilaginous and bony contours of the distal femur. Cartilage thickness at femoral condyles was assessed. Intraclass-correlation-coefficient (ICC) and Pearson's correlation were used for statistical analysis. Mean difference between cartilaginous and bony femoral torsion in girls was -1.1°±1.75 (range, -5.4° to 3.1°) for R1 and -1.64°±1.67 (-6.3° to 2.1°) for R2, in boys -1.5°±1.87 (-8.4° to 1.1°) for R1 and -2.28°±1.48 (-4.3° to 9.7°) for R2. Weak-to-moderate correlations between difference of cartilaginous-versus-bony measurements and cartilage thickness (r=-0.15 to -0.55, P<0.001-0.46) or age (r=-0.33 to 0.46, P<0.001-0.006) were found for both genders. Intermethod-ICC for cartilaginous versus bony femoral torsion measurements was 0.99/0.99 for R1/R2 in girls, and 0.99/0.98 in boys. There is only a small difference when measuring femoral torsion through cartilaginous versus bony contours, and no major difference in this between boys and girls. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Binding Energy Distribution Analysis Method: Hamiltonian Replica Exchange with Torsional Flattening for Binding Mode Prediction and Binding Free Energy Estimation.

    Science.gov (United States)

    Mentes, Ahmet; Deng, Nan-Jie; Vijayan, R S K; Xia, Junchao; Gallicchio, Emilio; Levy, Ronald M

    2016-05-10

    Molecular dynamics modeling of complex biological systems is limited by finite simulation time. The simulations are often trapped close to local energy minima separated by high energy barriers. Here, we introduce Hamiltonian replica exchange (H-REMD) with torsional flattening in the Binding Energy Distribution Analysis Method (BEDAM), to reduce energy barriers along torsional degrees of freedom and accelerate sampling of intramolecular degrees of freedom relevant to protein-ligand binding. The method is tested on a standard benchmark (T4 Lysozyme/L99A/p-xylene complex) and on a library of HIV-1 integrase complexes derived from the SAMPL4 blind challenge. We applied the torsional flattening strategy to 26 of the 53 known binders to the HIV Integrase LEDGF site found to have a binding energy landscape funneled toward the crystal structure. We show that our approach samples the conformational space more efficiently than the original method without flattening when starting from a poorly docked pose with incorrect ligand dihedral angle conformations. In these unfavorable cases convergence to a binding pose within 2-3 Å from the crystallographic pose is obtained within a few nanoseconds of the Hamiltonian replica exchange simulation. We found that torsional flattening is insufficient in cases where trapping is due to factors other than torsional energy, such as the formation of incorrect intramolecular hydrogen bonds and stacking. Work is in progress to generalize the approach to handle these cases and thereby make it more widely applicable.

  13. Nonlinear effects in the torsional adjustment of interacting DNA.

    Science.gov (United States)

    Kornyshev, A A; Wynveen, A

    2004-04-01

    DNA molecules in solution, having negatively charged phosphates and countercations readsorbed on its surface, possess a distinct charge separation motif to interact electrostatically. If their double-helical structure were ideal, duplexes in parallel juxtaposition could choose azimuthal alignment providing attraction, or at least a reduction of repulsion, between them. But duplexes are not perfect staircases and the distortions of their helical structure correlate with their base pair texts. If the patterns of distortions on the opposing molecules are uncorrelated, the mismatch will accumulate as a random walk and attraction vanishes. Based on this idea, a model of recognition of homologous sequences has been proposed [A. A. Kornyshev and S. Leikin, Phys. Rev. Lett. 86, 3666 (2001)]. But DNA has torsional elasticity. How will this help to relax a mismatch between the charge distributions on two nonhomologous DNA's? In the same work, the solution of this problem has been mapped onto a frustrated sine Gordon equation in a nonlocal random field (where the latter represents a pattern of twist angle distortions on the opposing molecules), but the results had been obtained in the limit of torsionally rigid molecules. In the present paper, by solving this equation numerically, we find a strongly nonlinear relaxation mechanism which utilizes static kink-soliton modes triggered by the "random field." In the range of parameters where the solitons do not emerge, we find good agreement with the results of a variational study [A. G. Cherstvy, A. A. Kornyshev, and S. Leikin, J. Phys. Chem. B (to be published)]. We reproduce the first-order transitions in the interaxial separation dependence, but detect also second-order or weak first-order transitions for shorter duplexes. The recognition energy between two nonhomologous DNA sequences is calculated as a function of interaxial separation and the length of juxtaposition. The soliton-caused kinky length dependence is discussed in

  14. Carbon nanotube torsional springs for regenerative braking systems

    Science.gov (United States)

    Liu, Sanwei; Martin, Corbin; Lashmore, David; Schauer, Mark; Livermore, Carol

    2015-10-01

    The modeling and demonstration of large stroke, high energy density and high power density torsional springs based on carbon nanotube (CNT) yarns is reported, as well as their application as energy-storing actuators for regenerative braking systems. An originally untwisted CNT yarn is cyclically loaded and unloaded in torsion, with the maximum rotation angle increasing incrementally until failure. The measured average extractable energy density values are 2.9 kJ kg-1  ±  1.2 kJ kg-1 and 3.4 kJ kg-1  ±  0.4 kJ kg-1 for 1-ply CNT yarns and 2-ply CNT yarns, respectively. Additionally, a regenerative braking system is demonstrated to capture the kinetic energy of a wheel and store it as elastic energy in twisted CNT yarns. When the yarn’s twist is released, the stored energy reaccelerates the wheel. The measured energy and mean power densities of the CNT yarns in the simple regenerative braking setup are on average 3.3 kJ kg-1 and 0.67 kW kg-1, respectively, with maximum measured values of up to 4.7 kJ kg-1 and 1.2 kW kg-1, respectively. A slightly lower energy density of up to 1.2 kJ kg-1 and a 0.29 kW kg-1 mean power density are measured for CNT yarns in a more complex setup that mimics a unidirectional rotating regenerative braking mechanism.

  15. Nonlinear effects in the torsional adjustment of interacting DNA

    Science.gov (United States)

    Kornyshev, A. A.; Wynveen, A.

    2004-04-01

    DNA molecules in solution, having negatively charged phosphates and countercations readsorbed on its surface, possess a distinct charge separation motif to interact electrostatically. If their double-helical structure were ideal, duplexes in parallel juxtaposition could choose azimuthal alignment providing attraction, or at least a reduction of repulsion, between them. But duplexes are not perfect staircases and the distortions of their helical structure correlate with their base pair texts. If the patterns of distortions on the opposing molecules are uncorrelated, the mismatch will accumulate as a random walk and attraction vanishes. Based on this idea, a model of recognition of homologous sequences has been proposed [A. A. Kornyshev and S. Leikin, Phys. Rev. Lett. 86, 3666 (2001)]. But DNA has torsional elasticity. How will this help to relax a mismatch between the charge distributions on two nonhomologous DNA’s? In the same work, the solution of this problem has been mapped onto a frustrated sine Gordon equation in a nonlocal random field (where the latter represents a pattern of twist angle distortions on the opposing molecules), but the results had been obtained in the limit of torsionally rigid molecules. In the present paper, by solving this equation numerically, we find a strongly nonlinear relaxation mechanism which utilizes static kink-soliton modes triggered by the “random field.” In the range of parameters where the solitons do not emerge, we find good agreement with the results of a variational study [A. G. Cherstvy, A. A. Kornyshev, and S. Leikin, J. Phys. Chem. B (to be published)]. We reproduce the first-order transitions in the interaxial separation dependence, but detect also second-order or weak first-order transitions for shorter duplexes. The recognition energy between two nonhomologous DNA sequences is calculated as a function of interaxial separation and the length of juxtaposition. The soliton-caused kinky length dependence is

  16. 〈110〉 Fiber Texture Evolution of Ferrite Wires during Drawn-torsion and Drawn-annealing-torsion Process

    Institute of Scientific and Technical Information of China (English)

    Y.D. Liu; Y.D. Zhang; A. Tidul; L. Zuo

    2012-01-01

    In this paper, the texture and microstructure evolution of drawn-torsion and drawn-annealing-torsion ferrite wires are studied by electron back scattering diffraction (EBSD) in order to investigate the special torsion texture evolution. Compared to the simulation results, the stable texture components {110}〈 110 〉 and {110}〈112〉 in both drawn-torsion and drawn-annealing-torsion wires display different evolution processes. The texture of the drawn-annealing-torsion wire fits to the Taylor model. A special texture evolution is found in drawn-torsion wires, related to the grain shape, and the heterogeneous deformation. A new plastic deformation viewpoint is suggested based on the special microstructure of drawn ferrite wire.

  17. Torsion method for measuring piezooptic coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Skab, I.; Smaga, I.; Savaryn, V.; Vasylkiv, Yu.; Vlokh, R. [Institute of Physical Optics, Lviv (Ukraine)

    2011-01-15

    We develop and describe analytically a torsion method for measuring piezooptic coefficients associated with shear stresses. It is shown that the method enables to increase significantly the accuracy of determination of piezooptic coefficients. The method and the appropriate apparatus are verified experimentally on the example of LiNbO{sub 3} crystals. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Mannarelli, Massimo; Pagliaroli, Giulia; Parisi, Alessandro; Pilo, Luigi; Tonelli, Francesco, E-mail: massimo@lngs.infn.it [INFN, Laboratori Nazionali del Gran Sasso, Via G. Acitelli, 22, I-67100 Assergi (AQ) (Italy)

    2015-12-20

    Strange stars are one of the possible compact stellar objects that can form after a supernova collapse. We consider a model of a strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting (CCSC) layer. These two phases constitute the quarksphere, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming an ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming an electron layer a few hundred fermi thick separating the ionic crust from the underlying quark matter. The ionic matter and the CCSC matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fraction larger than 10{sup −4} of the energy of a Vela-like glitch is conveyed to a torsional oscillation, the ionic crust will likely break. The reason is that the very rigid and heavy CCSC crust layer will absorb only a small fraction of the glitch energy, leading to a large-amplitude torsional oscillation of the ionic crust. The maximum stress generated by the torsional oscillation is located inside the ionic crust and is very close to the star’s surface. This peculiar behavior leads to a much easier crust cracking than in standard neutron stars.

  19. Electrostatically actuated torsional resonant sensors and switches

    KAUST Repository

    Younis, Mohammad I.

    2016-12-29

    Embodiments in accordance of a torsional resonant sensor disclosure is configured to actuate a beam structure using electrostatic actuation with an AC harmonic load (e.g., AC and DC voltage sources) that is activated upon detecting a particular agent having a mass above a predefined level. In various embodiments, the beam structure may be different types of resonant structures that is at least partially coated or layered with a selective material.

  20. Is Torsion a Fundamental Physical Field?

    CERN Document Server

    Lecian, Orchidea Maria; Montani, Giovanni

    2016-01-01

    The local Lorentz group is introduced in flat space-time, where the resulting Dirac and Yang-Mills equations are found, and then generalized to curved space-time: if matter is neglected, the Lorentz connection is identified with the contortion field, while, if matter is taken into account, both the Lorentz connection and the spinor axial current are illustrated to contribute to the torsion of space-time.

  1. Gravitomagnetic effect and spin-torsion coupling

    CERN Document Server

    Sousa, A A

    2003-01-01

    We study the gravitomagnetic effect in the context of absolute parallelism with the use of a modified geodesic equation via a free parameter b. We calculate the time difference in two atomic clocks orbiting the Earth in opposite directions and find a small correction due to the coupling between the torsion of the spacetime and the internal structure of atomic clocks measured by the free parameter.

  2. the Analysis of Coupled Lateral Torsional Vibrations

    Directory of Open Access Journals (Sweden)

    Tomasz Szolc

    2000-01-01

    Full Text Available In the paper, dynamic investigations of the rotor shaft systems are performed by means of the discrete-continuous mechanical models. In these models the rotor shaft segments are represented by the rotating cylindrical flexurally and torsionally deformable continuous viscoelastic elements. These elements are mutually connected according to the structure of the real system in the form of a stepped shaft which is suspended on concentrated inertial viscoelastic supports of linear or non-linear characteristics. At appropriate shaft crosssections, by means of massless membranes, there are attached rigid rings representing rotors, disks, gears, flywheels and others. The proposed model enables us to investigate coupled linear or non-linear lateral torsional Vibrations of the rotating systems in steady-state and transient operating conditions. As demonstrative examples, for the steam turbo-compressor under coupled lateral torsional vibrations, the transient response due to a blade falling out from the turbine rotor as well as the steady-state response in the form of parametric resonance caused by residual unbalances are presented.

  3. Design of a nonlinear torsional vibration absorber

    Science.gov (United States)

    Tahir, Ammaar Bin

    Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

  4. Isolated Penile Torsion in Brothers: A Case Report

    Directory of Open Access Journals (Sweden)

    Metin Gunduz

    2012-04-01

    Full Text Available Penile torsion can be congenital and associated with hypospadias and chordee, or can be acquired after circumcision. The incidence of isolated neonatal penile torsion was 1.7 to 27% in the literature. The majority were between 10 and deg; and 20 and deg;. Generally, torsion was to the left in cases. The techniques for correction of penile torsion described in the literature are penile de-gloving and reattaching of skin, resection of Buck's fascia incising the base of the penis and removing angular ellipses of corporeal tissue with subsequent plication of tunica, and dorsal dartos flap rotation in severe cases. In conclusion, penile torsion may be familial. Therefore, brothers should be examined carefully. The degloving and realignment technique is successful in isolated penile torsion. [Arch Clin Exp Surg 2012; 1(2.000: 122-124

  5. Analytic Torsion of Z_2-graded Elliptic Complexes

    CERN Document Server

    Mathai, Varghese

    2010-01-01

    We define analytic torsion of Z_2-graded elliptic complexes as an element in the graded determinant line of the cohomology of the complex, generalizing most of the variants of Ray-Singer analytic torsion in the literature. It applies to a myriad of new examples, including flat superconnection complexes, twisted analytic and twisted holomorphic torsions, etc. The definition uses pseudo-differential operators and residue traces. We also study properties of analytic torsion for Z_2-graded elliptic complexes, including the behavior under variation of the metric. For compact odd dimensional manifolds, the analytic torsion is independent of the metric, whereas for even dimensional manifolds, a relative version of the analytic torsion is independent of the metric. Finally, the relation to topological field theories is studied.

  6. Torsional Alfven waves in stratified and expanding magnetic flux tubes

    OpenAIRE

    2011-01-01

    The effects of both density stratification and magnetic field expansion on torsional Alfven waves in magnetic flux tubes are studied. The frequencies, the period ratio P1/P2 of the fundamental and its first-overtone, and eigenfunctions of torsional Alfven modes are obtained. Our numerical results show that the density stratification and magnetic field expansion have opposite effects on the oscillating properties of torsional Alfven waves.

  7. Cooling Torsional Nanomechanical Vibration by Spin-Orbit Interactions

    Institute of Scientific and Technical Information of China (English)

    ZHAO Nan; ZHOU Duan-Lu; ZHU Jia-Lin

    2008-01-01

    We propose and study a spin-orbit interaction based mechanism to actively cool down the torsional vibration of a nanomechanical resonator made by semiconductor materials. We show that the spin-orbit interactions of electrons can induce a coherent coupling between the electron spins and the torsional modes of nanomechanical vibration. This coupling leads to an active cooling for the torsional modes through the dynamical thermalization of the resonator by the spin ensemble.

  8. Constraining Torsion in Maximally symmetric (sub)spaces

    CERN Document Server

    Sur, Sourav

    2013-01-01

    We look into the general aspects of space-time symmetries in presence of torsion, and how the latter is affected by such symmetries. Focusing in particular to space-times which either exhibit maximal symmetry on their own, or could be decomposed to maximally symmetric subspaces, we work out the constraints on torsion in two different theoretical schemes. We show that at least for a completely antisymmetric torsion tensor (for e.g. the one motivated from string theory), an equivalence is set between these two schemes, as the non-vanishing independent torsion tensor components turn out to be the same.

  9. Alpha surfaces for complex space-times with torsion

    CERN Document Server

    Esposito, G

    1993-01-01

    This paper studies necessary conditions for the existence of alpha-surfaces in complex space-time manifolds with nonvanishing torsion. For these manifolds, Lie brackets of vector fields and spinor Ricci identities contain explicitly the effects of torsion. This leads to an integrability condition for alpha-surfaces which does not involve just the self-dual Weyl spinor, as in complex general relativity, but also the torsion spinor, in a nonlinear way, and its covariant derivative. Interestingly, a particular solution of the integrability condition is given by conformally right-flat and right-torsion-free space-times.

  10. Isolated Penile Torsion in Brothers: A Case Report

    OpenAIRE

    2012-01-01

    Penile torsion can be congenital and associated with hypospadias and chordee, or can be acquired after circumcision. The incidence of isolated neonatal penile torsion was 1.7 to 27% in the literature. The majority were between 10 and deg; and 20 and deg;. Generally, torsion was to the left in cases. The techniques for correction of penile torsion described in the literature are penile de-gloving and reattaching of skin, resection of Buck's fascia incising the base of the penis and removing an...

  11. Association of Torsion With Testicular Cancer: A Retrospective Study.

    Science.gov (United States)

    Uguz, Sami; Yilmaz, Sercan; Guragac, Ali; Topuz, Bahadır; Aydur, Emin

    2016-02-01

    Testicular torsion is a medical emergency that usually requires surgical exploration. However, testicular malignancy has been anecdotally reported with the association of torsion in surgical specimens, and the published data remain scant on the association of torsion with testicular tumors. By retrospective medical record review, we identified 32 patients who had been diagnosed with testicular torsion, 20 of whom had undergone orchiectomy. Of these 20 patients, 2 were diagnosed with a malignancy. Our study, the largest case series to date, has shown an association between testicular torsion and testicular cancer of 6.4%. Testicular torsion is a medical emergency that usually requires surgical exploration. However, testicular malignancy has been anecdotally reported in association with torsion in surgical specimens. However, the published data remain scant on the association between torsion and the presence of testicular tumors. The present retrospective study explored the association between torsion and testicular cancer in patients with testicular torsion undergoing orchiectomy during scrotal exploration. A medical record review was performed of patients who had had a diagnosis of testicular torsion from January 2003 to February 2015. The clinicopathologic characteristics of the patients were recorded. A total of 32 patients were identified. Their mean age was 21.1 years (range, 7-39 years). All the patients had unilateral testicular torsion, which affected the left side in 17 and the right side in 15. Manual detorsion was successful in 6 patients, and 26 patients underwent emergency surgery with testicular detorsion (6 fixation surgery and 20 orchiectomy). The type of incision was scrotal in 6, inguinal in 10, and unspecified in 4. Pathologic examination of the orchiectomy specimens showed malignancy in 2 cases (seminoma and malign mixed germ cell tumor). To the best of our knowledge, the present single-center case series is the largest case series to date of

  12. Torsional Newton-Cartan geometry from Galilean gauge theory

    CERN Document Server

    Banerjee, Rabin

    2016-01-01

    Using the recently advanced Galilean gauge theory we give a comprehensive construction of torsional Newton Cartan geometry. A complete (implicit) expression of the torsion tensor for the Newton Cartan spacetime is provided. The implicit expression containing torsion is similar to contorsion tensor in Riemann - Cartan space time and it contains an arbitrary shift. This is similar to the shift given by Dautcourt's formula for the symmetric part of the connection. These findings are new in the literature. The well known result for the temporal part of torsion is reproduced from our expression.

  13. A novel approach for manual de-torsion of an atypical (outward) testicular torsion with bedside Doppler ultrasonography guidance.

    Science.gov (United States)

    Güneş, Mustafa; Umul, Mehmet; Çelik, Ahmet Orhan; Armağan, Hamit Hakan; Değirmenci, Bumin

    2015-01-01

    A 17-year-old boy presented with right testicular torsion to the lateral side. Torsion was diagnosed by physical examination; the colour Doppler ultrasonography (CDU) confirmed right testicular torsion with minimal peripheral hydrocele. Transverse and longitudinal examination of the spermatic cord with ultrasound and CDU revealed a counter-clockwise testicular torsion. Manual de-torsion was performed in a clockwise direction (720o) and testicular blood flow and the neutral position of the spermatic cord were confirmed by CDU. We did not encounter a residual twist of the spermatic cord upon surgical exploration. In our experience, ultrasound and CDU may predict the direction of testicular torsion and may allow appropriate management of cases prior to surgery.

  14. Piezoelectric d36 in-plane shear-mode of lead-free BZT-BCT single crystals for torsion actuation

    Science.gov (United States)

    Berik, P.; Chang, W.-Y.; Jiang, X.

    2017-01-01

    We report the study of piezoelectric direct torsion actuation mechanism using lead-free piezoelectric d36 in-plane shear-mode BZT-BCT single crystals. The generated angle of twist of the piezoelectric torsion actuator was obtained from the transverse deflection measurement using a laser vibrometer. The bi-morph torsional actuator, consisting of two lead-free piezoelectric BZT-BCT in-plane shear-mode single crystals with a giant piezoelectric d36 shear strain coefficient of 1590 pC/N, provided a rate of twist of 34.12 mm/m under a quasi-static 15 V drive. The experimental benchmark was further modelled and verified by the ANSYS software using three dimensional (3D) piezoelectric finite elements. The experimental results revealed that lead-free piezoelectric BZT-BCT d36-mode single crystal is a superior candidate for piezoelectric torsion actuation. This lead-free piezoelectric BZT-BCT d36-mode torsion actuator can be effectively applied in torsional deformation control by taking into account the environmental considerations.

  15. Do physical examination and CT-scan measures of femoral neck anteversion and tibial torsion relate to each other?

    Science.gov (United States)

    Sangeux, Morgan; Mahy, Jessica; Graham, H Kerr

    2014-01-01

    Informed clinical decision making for femoral and/or tibial de-rotation osteotomies requires accurate measurement of patient function through gait analysis and anatomy through physical examination of bony torsions. Validity of gait analysis has been extensively studied; however, controversy remains regarding the accuracy of physical examination measurements of femoral and tibial torsion. Comparison between CT-scans and physical examination measurements of femoral neck anteversion (FNA) and external tibial torsion (ETT) were retrospectively obtained for 98 (FNA) and 64 (ETT) patients who attended a tertiary hospital for instrumented gait analysis between 2007 and 2010. The physical examination methods studied for femoral neck anteversion were the trochanteric prominence angle test (TPAT) and the maximum hip rotation arc midpoint (Arc midpoint) and for external tibial torsion the transmalleolar axis (TMA). Results showed that all physical examination measurements statistically differed to the CT-scans (bias(standard deviation): -2(14) for TPAT, -10(12) for Arc midpoint and -16(9) for TMA). Bland and Altman plots showed that method disagreements increased with increasing bony torsions in all cases but notably for TPAT. Regression analysis showed that only TMA and CT-scan measurement of external tibial torsion demonstrated good (R(2)=57%) correlation. Correlations for both TPAT (R(2)=14%) and Arc midpoint (R(2)=39%) with CT-scan measurements of FNA were limited. We conclude that physical examination should be considered as screening techniques rather than definitive measurement methods for FNA and ETT. Further research is required to develop more accurate measurement methods to accompany instrumented gait analysis. Copyright © 2013. Published by Elsevier B.V.

  16. Development of a second generation torsion balance based on a spherical superconducting suspension.

    Science.gov (United States)

    Hammond, Giles D; Speake, Clive C; Matthews, Anthony J; Rocco, Emanuele; Peña-Arellano, Fabian

    2008-02-01

    This paper describes the development of a second generation superconducting torsion balance to be used for a precision measurement of the Casimir force and a short range test of the inverse square law of gravity at 4.2 K. The instrument utilizes niobium (Nb) as the superconducting element and employs passive damping of the parasitic modes of oscillation. Any contact potential difference between the torsion balance and its surroundings is nulled to within approximately 50 mV by applying known DC biases and fitting the resulting parabolic relationship between the measured torque and the applied voltage. A digital proportional-integral-derivative servo system has been developed and characterized in order to control the azimuthal position of the instrument. The angular acceleration and displacement noise are currently limited by the capacitive sensor at the level 3x10(-8) rad s(-2)/ squarerootHz and 30 nm/ squarerootHz at 100 mHz. The possibility of lossy dielectric coatings on the surface of the torsion balance test masses is also investigated. Our measurements show that the loss angles delta are (1.5+/-2.3)x10(-4) and (2.0+/-2.2)x10(-4) at frequencies of 5 and 10 mHz, respectively. These values of loss are not significant sources of error for measurements of the Casimir force using this experimental setup.

  17. Investigating Fracture Behaviors of Polymer and Polymeric Composite Materials Using Spiral Notch Torsion Test

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL; Ren, Fei [ORNL; Tan, Ting [ORNL; Lara-Curzio, Edgar [ORNL; Agastra, Pancasatya [Montana State University; Mandell, John [Montana State University; Bertelsen, Williams D. [Gougeon Brothers, Inc.; LaFrance, Carl M. [Molded Fiber Glass Companies

    2011-01-01

    Wind turbine blades are usually fabricated from fiber reinforced polymeric (FRP) materials, which are subject to complex loading conditions during service. The reliability of the blades thus depends on the mechanical behaviors of the FRP under various loading conditions. Specifically, the fracture behavior of FRP is of great importance to both the scientific research community and the wind industry. In the current project, a new testing technique is proposed based on the spiral notch torsion test (SNTT) to study the fracture behavior of composite structures under mixed mode loading conditions, particularly under combined Mode I (flexural or normal tensile stress) and Mode III (torsional shear stress) loading. For the SNTT test method, round-rod specimens with V-grooved spiral lines are subjected to pure torsion. Depending on the pitch angle of the spiral lines, pure Mode I, pure Mode III, or mixed Mode I/Mode III loading conditions can be simulated. A three dimensional finite element analysis is then used to evaluate the fracture toughness and energy release rate of SNTT specimens. In the current study, both epoxy and fiberglass reinforced epoxy materials are investigated using the SNTT technique. This paper will discuss the fracture behaviors of mode I and mixed mode samples, with or without fatigue precrack. In addition, results from fractographic study and finite element analysis will be presented and discussed in detail.

  18. Echocardiographic Assessment of Left Ventricle Torsion by Tissue Doppler and Velocity Vector Imaging

    Directory of Open Access Journals (Sweden)

    Zahra Ojaghi-Haghighi

    2014-08-01

    Full Text Available Introduction Left ventricular (LV twist is believed to store potential energy and plays an important role in generating diastolic suction. Recent advances in echocardiography techniques have allowed quantification of LV twist. The aim of the present study was to compare LV twist and torsion in healthy human subjects determined by velocity vector imaging (VVI and tissue Doppler imaging (TDI at rest. Materials and Methods All volunteers (72 healthy subjects underwent complete echocardiographic study and LV torsional parameters were assessed using VVI or TDI methods. LV rotation at apical and basal short-axis levels was calculated throughout cardiac cycle and LV twist was defined as net difference between rotation angles of the two levels. The LV torsion was calculated as the LV twist divided by the LV end-diastolic length. Results Twist degree was significantly lower in the VVI group than the TDI group (11.4±2.4º vs.14.1±3.0º, p

  19. Effect of pile-cap connection on behavior of torsionally loaded pile groups

    Institute of Scientific and Technical Information of China (English)

    Ling-gang KONG; Li-min ZHANG

    2008-01-01

    To evaluate the respouses of fixed and pinned pile groups under torsiun, a method is presented to analyze the nonlinear behavior of free-standing pile groups with rigid pile caps. The method is capable of simulating the nonlinear soil response in the near field usingp-y and τ-θ curves, the far-field interactions through Mindlin's and Randolph's elastic solutions, and the coupling effect of lateral resistance on torsional resistance of the individual piles using an empirical factor. Based on comparisons of the solutions for fixedand pinned-head, 1×2, 2×2, and 3×3 pile groups subjected to torsion, it was found that pile-cap connection significantly influences the torsional capacity of pile groups and the assignment of applied torques in the pile groups. In this study, the applied torques for the pinned-head pile groups are only 44%~64% of those for the corresponding fixed-head pile groups at a twist angle of 2°. Such a difference is mainly due to the change of the lateral resistances of individual piles in the groups.

  20. Surface strain gradient effects in the torsion of a circular bar with radial cracks

    Science.gov (United States)

    Xu, Yang; Wang, Xu

    2016-12-01

    We study the contribution of surface strain gradient elasticity to the Saint-Venant torsion problem of a circular cylinder containing a radial crack. The surface strain gradient elasticity is incorporated by using an enriched version of the continuum-based surface/interface model of Gurtin and Murdoch. By using Green's function method, the original boundary value problem is reduced to a Cauchy singular integro-differential equation which can be numerically solved by using the Gauss-Chebyshev integration formula, the Chebyshev polynomials and the collocation method. Due to the presence of surface strain gradient elasticity on the crack faces, the stresses are bounded at the crack tips. The torsion problem of a circular cylinder containing two symmetric collinear radial cracks of equal length with surface strain gradient elasticity is also solved by using a similar method. Numerical results indicate that the surface strain gradient effect exerts a significant influence on the torsional rigidity and the jump in warping function. In particular, the jump in warping function forms a cusp shape with zero enclosed angle at the crack tips.

  1. Structural Modifications for Torsional Vibration Control of Shafting Systems Based on Torsional Receptances

    Directory of Open Access Journals (Sweden)

    Zihao Liu

    2016-01-01

    Full Text Available Torsional vibration of shafts is a very important problem in engineering, in particular in ship engines and aeroengines. Due to their high levels of integration and complexity, it is hard to get their accurate structural data or accurate modal data. This lack of data is unhelpful to vibration control in the form of structural modifications. Besides, many parts in shaft systems are not allowed to be modified such as rotary inertia of a pump or an engine, which is designed for achieving certain functions. This paper presents a strategy for torsional vibration control of shaft systems in the form of structural modifications based on receptances, which does not need analytical or modal models of the systems under investigation. It only needs the torsional receptances of the system, which can be obtained by testing simple auxiliary structure attached to relevant locations of the shaft system and using the finite element model (FEM of the simple structure. An optimization problem is constructed to determine the required structural modifications, based on the actual requirements of modal frequencies and mode shapes. A numerical experiment is set up and the influence of several system parameters is analysed. Several scenarios of constraints in practice are considered. The numerical simulation results demonstrate the effectiveness of this method and its feasibility in solving torsional vibration problems in practice.

  2. Transverse posterior element fractures associated with torsion

    Energy Technology Data Exchange (ETDEWEB)

    Abel, M.S.

    1989-01-01

    Six examples of a previously undescribed class of transverse vertebral element fractures are presented. These fractures differ from Chance and Smith fractures and their variants in the following respects: (1) the etiology is torsion and not flexion; (2) there is neither distraction of posterior ring fragments nor posterior ligament tears; (3) in contrast to Chance and Smith fractures, extension of the fracture into the vertebral body is absent or minimal; (4) the transverse process of the lumbar vertebra is avulsed at its base with a vertical fracture, not split horizontally. These fractures occur in cervical, lumbar, and sacral vertebrae in normal or compromised areas of the spine.

  3. Embeddings of Kleinian Groups with Torsion

    Institute of Scientific and Technical Information of China (English)

    Shi Cheng WANG; Qing ZHOU

    2001-01-01

    Rips conjectured that a non-elementary word hyperbolic group is cohopfian if and only ifit is freely indecomposable. The results and examples in this paper show that cohopficity phenomenonin the case of word hyperbolic group with torsion is much more complicated than the conjecture. Inparticular, the cohopficity of such groups is not determined by the numbers of their ends and thecohopficity is not preserved by finite index subgroups. Our results and examples arise from Kleiniangroups. Orbifold structures and orbifold maps are the new tools in our discussions.

  4. Microstructure characterization of Cu processed by compression with oscillatory torsion

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, K., E-mail: kinga.rodak@polsl.pl [Institute of Materials Science, Silesian University of Technology, Krasińskiego 8, 40-019 Katowice (Poland); Pawlicki, J., E-mail: jacek.pawlicki@polsl.pl [Department of Automotive Vehicle Construction, Silesian University of Technology, Krasińskiego 8, 40–019 Katowice (Poland)

    2014-08-15

    High purity Cu (99.9%) was subjected to severe plastic deformation up to a total effective strain ε{sub ft} = 130 through compression with the oscillatory torsion method at room temperature. This method produces an ultrafine grain microstructure. The microstructure evolution was investigated with respect to the value of the total effective strain using a scanning electron microscope with an electron-backscattered diffraction technique and a scanning transmission electron microscope. The results of the structural analyses show that increasing ε{sub ft} from 2 to 50 causes progress in the grain refinement. A quantitative study of the microstructure parameters, such as fraction of high angle boundaries, grain and subgrain diameter, and the area fraction of grains up to 1 μm, shows that deformation at ε{sub ft} = 45 guaranteed the best conditions for refining the microstructure of Cu. Using high values of ε{sub ft} in the range 60 to 130 restricts grain refinement because intensive recovery begins to dominate in the microstructure. - Highlights: • Cu was processed by SPD metodto an effective strain 130. • The microstructure evolution has been investigated. • The method allows to produce an ultrafine grain microstructure.

  5. Nonlinear nonuniform torsional vibrations of bars by the boundary element method

    Science.gov (United States)

    Sapountzakis, E. J.; Tsipiras, V. J.

    2010-05-01

    In this paper a boundary element method is developed for the nonuniform torsional vibration problem of bars of arbitrary doubly symmetric constant cross-section taking into account the effect of geometrical nonlinearity. The bar is subjected to arbitrarily distributed or concentrated conservative dynamic twisting and warping moments along its length, while its edges are supported by the most general torsional boundary conditions. The transverse displacement components are expressed so as to be valid for large twisting rotations (finite displacement-small strain theory), thus the arising governing differential equations and boundary conditions are in general nonlinear. The resulting coupling effect between twisting and axial displacement components is considered and torsional vibration analysis is performed in both the torsional pre- or post-buckled state. A distributed mass model system is employed, taking into account the warping, rotatory and axial inertia, leading to the formulation of a coupled nonlinear initial boundary value problem with respect to the variable along the bar angle of twist and to an "average" axial displacement of the cross-section of the bar. The numerical solution of the aforementioned initial boundary value problem is performed using the analog equation method, a BEM based method, leading to a system of nonlinear differential-algebraic equations (DAE), which is solved using an efficient time discretization scheme. Additionally, for the free vibrations case, a nonlinear generalized eigenvalue problem is formulated with respect to the fundamental mode shape at the points of reversal of motion after ignoring the axial inertia to verify the accuracy of the proposed method. The problem is solved using the direct iteration technique (DIT), with a geometrically linear fundamental mode shape as a starting vector. The validity of negligible axial inertia assumption is examined for the problem at hand.

  6. Constraints on torsion from bounds on lorentz violation.

    Science.gov (United States)

    Kostelecký, V Alan; Russell, Neil; Tasson, Jay D

    2008-03-21

    Exceptional sensitivity to space-time torsion can be achieved by searching for its couplings to fermions. Recent experimental searches for Lorentz violation are exploited to extract new constraints involving 19 of the 24 independent torsion components down to levels of order 10(-31) GeV.

  7. Hydrostatic self-aligning axial/torsional mechanism

    Science.gov (United States)

    O'Connor, Daniel G.; Gerth, Howard L.

    1990-01-01

    The present invention is directed to a self-aligning axial/torsional loading mechanism for testing the strength of brittle materials which are sensitive to bending moments. Disposed inside said self-aligning loading mechanism is a frictionless hydrostatic ball joint with a flexure ring to accommodate torsional loads through said ball joint.

  8. Mechanical origins of rightward torsion in early chick brain development

    Science.gov (United States)

    Chen, Zi; Guo, Qiaohang; Dai, Eric; Taber, Larry

    2015-03-01

    During early development, the neural tube of the chick embryo undergoes a combination of progressive ventral bending and rightward torsion. This torsional deformation is one of the major organ-level left-right asymmetry events in development. Previous studies suggested that bending is mainly due to differential growth, however, the mechanism for torsion remains poorly understood. Since the heart almost always loops rightwards that the brain twists, researchers have speculated that heart looping affects the direction of brain torsion. However, direct evidence is lacking, nor is the mechanical origin of such torsion understood. In our study, experimental perturbations show that the bending and torsional deformations in the brain are coupled and that the vitelline membrane applies an external load necessary for torsion to occur. Moreover, the asymmetry of the looping heart gives rise to the chirality of the twisted brain. A computational model and a 3D printed physical model are employed to help interpret these findings. Our work clarifies the mechanical origins of brain torsion and the associated left-right asymmetry, and further reveals that the asymmetric development in one organ can induce the asymmetry of another developing organ through mechanics, reminiscent of D'Arcy Thompson's view of biological form as ``diagram of forces''. Z.C. is supported by the Society in Science - Branco Weiss fellowship, administered by ETH Zurich. L.A.T acknowledges the support from NIH Grants R01 GM075200 and R01 NS070918.

  9. Torsion of right middle lobe after a right upper lobectomy

    Directory of Open Access Journals (Sweden)

    Chen Tung-Ying

    2009-04-01

    Full Text Available Abstract Lobar torsion after lung resection is a quite rare complication. A 50-year-old woman presented typical features on chest radiographs and CT(computed tomography scan of lobar torsion after a right upper lobectomy. After emergency lobectomy of right middle lobe, the patient recovered well and discharged 10 days after the second operation.

  10. The Reidemeister torsion of 3-manifolds

    CERN Document Server

    Nicolaescu, Liviu I

    2003-01-01

    This is a state-of-the-art introduction to the work of Franz Reidemeister, Meng Taubes, Turaev, and the author on the concept of torsion and its generalizations. Torsion is the oldest topological (but not with respect to homotopy) invariant that in its almost eight decades of existence has been at the center of many important and surprising discoveries. During the past decade, in the work of Vladimir Turaev, new points of view have emerged, which turned out to be the "right ones" as far as gauge theory is concerned. The book features mostly the new aspects of this venerable concept. The theoretical foundations of this subject are presented in a style accessible to those, who wish to learn and understand the main ideas of the theory. Particular emphasis is upon the many and rather diverse concrete examples and techniques which capture the subleties of the theory better than any abstract general result. Many of these examples and techniques never appeared in print before, and their choice is often justified by ...

  11. Krukenberg Tumor: A Rare Cause of Ovarian Torsion

    Directory of Open Access Journals (Sweden)

    Sameer Sandhu

    2012-01-01

    Full Text Available 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.

  12. Torsion and accelerating expansion of the universe in quadratic gravitation

    CERN Document Server

    Chee, Guoying

    2012-01-01

    Several exact cosmological solutions of a metric-affine theory of gravity with two torsion functions are presented. These solutions give a essentially different explanation from the one in most of previous works to the cause of the accelerating cosmological expansion and the origin of the torsion of the spacetime. These solutions can be divided into two classes. The solutions in the first class define the critical points of a dynamical system representing an asymptotically stable de Sitter spacetime. The solutions in the second class have exact analytic expressions which have never been found in the literature. The acceleration equation of the universe in general relativity is only a special case of them. These solutions indicate that even in vacuum the spacetime can be endowed with torsion, which means that the torsion of the spacetime has an intrinsic nature and a geometric origin. In these solutions the acceleration of the cosmological expansion is due to either the scalar torsion or the pseudoscalar torsi...

  13. Torsional and rotational coupling in non-rigid molecules

    CERN Document Server

    Omiste, Juan J

    2016-01-01

    We analyze theoretically the interplay between the torsional and the rotational motion of an aligned biphenyl-like molecule. To do so, we consider a transition between two electronic states with different internal torsional potentials, induced by means of a resonant laser pulse. The change in the internal torsional potential provokes the motion of the torsional wavepacket in the excited electronic state, modifying the structure of the molecule, and hence, its inertia tensor. We find that this process has a strong impact on the rotational wave function, displaying different behavior depending on the electronic states involved and their associated torsional potentials. We describe the dynamics of the system by considering the degree of alignment and the expectations values of the angular momentum operators for the overall rotation of the molecule.

  14. Peculiar torsion dynamical response of spider dragline silk

    Science.gov (United States)

    Liu, Dabiao; Yu, Longteng; He, Yuming; Peng, Kai; Liu, Jie; Guan, Juan; Dunstan, D. J.

    2017-07-01

    The torsional properties of spider dragline silks from Nephila edulis and Nephila pilipes spiders are investigated by using a torsion pendulum technique. A permanent torsional deformation is observed after even small torsional strain. This behaviour is quite different from that of the other materials tested here, i.e., carbon fiber, thin metallic wires, Kevlar fiber, and human hair. The spider dragline thus displays a strong energy dissipation upon the initial excitation (around 75% for small strains and more for a larger strain), which correspondingly reduces the amplitude of subsequent oscillations around the new equilibrium position. The variation of torsional stiffness in relaxation dynamics of spider draglines for different excitations is also determined. The experimental result is interpreted in the light of the hierarchical structure of dragline silk.

  15. Cosmological background torsion inhomogeneities and Lorentz violation in QED

    CERN Document Server

    Garcia de Andrade, L C

    2003-01-01

    A non-minimal photon-torsion axial coupling in the quantum electrodynamics (QED) framework is considered. The geometrical optics in Riemann-Cartan spacetime is considering and a plane wave expansion of the electromagnetic vector potential is considered leading to a set of the equations for the ray congruence. Since we are interested mainly on the torsion effects in this first report we just consider the Riemann-flat case composed of the Minkowskian spacetime with torsion. It is also shown that in torsionic de Sitter background the vacuum polarisation does alter the propagation of individual photons, an effect which is absent in Riemannian spaces. It is shown that the cosmological torsion background inhomogeneities induce Lorentz violation and massive photon modes in this QED.

  16. Effects of toughness anisotropy and combined tension, torsion, and bending loads on fracture behavior of ferritic nuclear pipe

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, R.; Marshall, C.; Ghadiali, N.; Wilkowski, G. [Battelle, Columbus, OH (United States)

    1997-04-01

    This paper summarizes work on angled through-wall-crack initiation and combined loading effects on ferritic nuclear pipe performed as part of the Nuclear Regulatory Commission`s research program entitled {open_quotes}Short Cracks In Piping an Piping Welds{close_quotes}. The reader is referred to Reference 1 for details of the experiments and analyses conducted as part of this program. The major impetus for this work stemmed from the observation that initially circumferentially oriented cracks in carbon steel pipes exhibited a high tendency to grow at a different angle when the cracked pipes were subjected to bending or bending plus pressure loads. This failure mode was little understood, and the effect of angled crack grown from an initially circumferential crack raised questions about how cracks in a piping system subjected to combined loading with torsional stresses would behave. There were three major efforts undertaken in this study. The first involved a literature review to assess the causes of toughness anisotropy in ferritic pipes and to develop strength and toughness data as a function of angle from the circumferential plane. The second effort was an attempt to develop a screening criterion based on toughness anisotropy and to compare this screening criterion with experimental pipe fracture data. The third and more significant effort involved finite element analyses to examine why cracks grow at an angle and what is the effect of combined loads with torsional stresses on a circumferentially cracked pipe. These three efforts are summarized.

  17. Optical Fiber Temperature and Torsion Sensor Based on Lyot-Sagnac Interferometer.

    Science.gov (United States)

    Shao, Li-Yang; Zhang, Xinpu; He, Haijun; Zhang, Zhiyong; Zou, Xihua; Luo, Bin; Pan, Wei; Yan, Lianshan

    2016-10-24

    An optical fiber temperature and torsion sensor has been proposed by employing the Lyot-Sagnac interferometer, which was composed by inserting two sections of high-birefringence (HiBi) fiber into the Sagnac loop. The two inserted sections of HiBi fiber have different functions; while one section acts as the temperature sensitive region, the other can be used as reference fiber. The temperature and twist sensor based on the proposed interferometer structure have been experimentally demonstrated. The experimental results show that the envelope of the output spectrum will shift with the temperature evolution. The temperature sensitivity is calculated to be -17.99 nm/°C, which is enlarged over 12 times compared to that of the single Sagnac interferometer. Additionally, the fringe visibility of the spectrum will change due to the fiber twist, and the test results reveal that the fringe visibility and twist angle perfectly conform to a Sine relationship over a 360° twist angle. Consequently, simultaneous torsion and temperature measurement could be realized by detecting the envelope shift and fringe visibility of the spectrum.

  18. On Torsion of Functionally Graded Elastic Beams

    Directory of Open Access Journals (Sweden)

    Marina Diaco

    2016-01-01

    Full Text Available The evaluation of tangential stress fields in linearly elastic orthotropic Saint-Venant beams under torsion is based on the solution of Neumann and Dirichlet boundary value problems for the cross-sectional warping and for Prandtl stress function, respectively. A skillful solution method has been recently proposed by Ecsedi for a class of inhomogeneous beams with shear moduli defined in terms of Prandtl stress function of corresponding homogeneous beams. An alternative reasoning is followed in the present paper for orthotropic functionally graded beams with shear moduli tensors defined in terms of the stress function and of the elasticity of reference inhomogeneous beams. An innovative result of invariance on twist centre is also contributed. Examples of functionally graded elliptic cross sections of orthotropic beams are developed, detecting thus new benchmarks for computational mechanics.

  19. Torsion-free Sheaves and ACM Schemes

    CERN Document Server

    Greco, S; Spreafico, M L

    2012-01-01

    In this paper we study short exact sequences $ 0 \\to \\mathcal P \\to \\mathcal N \\to \\ii_D(k) \\to 0 $ with $ \\mathcal P, \\mathcal N $ torsion--free sheaves and $ D $ closed projective scheme. This is a classical way to construct and study projective schemes (e.g. see \\cite{hart-1974}, \\cite{hart-2}, \\cite{mdp}, \\cite{serre-1960}). In particular, we give homological conditions on $ \\mathcal P $ and $ \\mathcal N $ that force $ D $ to be ACM, without constrains on its codimension. As last result, we prove that if $ \\mathcal N $ is a higher syzygy sheaf of an ACM scheme $ X,$ the scheme $ D $ we get contains $ X.$

  20. Torsional oscillations of nonbare strange stars

    CERN Document Server

    Mannarelli, Massimo; Parisi, Alessandro; Pilo, Luigi; Tonelli, Francesco

    2015-01-01

    Strange stars are one of the possible compact stellar objects that can be formed after a supernova collapse. We consider a model of strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting layer. These two phases constitute the {\\it quarksphere}, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming a ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming a few hundreds Fermi thick electron layer separating the ionic crust from the underlying quark matter. The ionic matter and the crystalline color superconducting matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fra...

  1. Torsion based universal MEMS logic device

    KAUST Repository

    Ilyas, Saad

    2015-10-28

    In this work we demonstrate torsion based complementary MEMS logic device, which is capable, of performing INVERTER, AND, NAND, NOR, and OR gates using one physical structure within an operating range of 0-10 volts. It can also perform XOR and XNOR with one access inverter using the same structure with different electrical interconnects. The paper presents modeling, fabrication and experimental calculations of various performance features of the device including lifetime, power consumption and resonance frequency. The fabricated device is 535 μm by 150 μm with a gap of 1.92 μm and a resonant frequency of 6.51 kHz. The device is capable of performing the switching operation with a frequency of 1 kHz.

  2. Laser micro-impulse torsion pendulum

    Institute of Scientific and Technical Information of China (English)

    Jing Li; Zhiping Tang

    2005-01-01

    @@ In order to investigate the feasibility regarding micro-satellite posture steering by laser micro-propulsion, a laser torsion pendulum has been set up so as to get first-hand basic physical and mechanical parameters on laser micro-propulsion. The instrumentation consists of the optical, mechanical, and electrical sub-systems.The optical system includes the main beam optics, the measuring optics, and the observation optics. The mechanical system includes the gyration apparatus, transverse translation stage, vertical translator, focal lenses translator, calibration pendulum translator, and vacuum chamber. For the electrical system a computer is used to control stepping motors to drive the above moving apparatuses. With this instrument the calibration experiment and laser ablation experiment have been carried out. The experimental results about 10.4%, which can satisfy the requirement of micro-impulse measurement.

  3. Doxorubicin, DNA torsion, and chromatin dynamics

    Science.gov (United States)

    Yang, Fan; Teves, Sheila S.; Kemp, Christopher J.; Henikoff, Steven

    2014-01-01

    Doxorubicin is one of the most important anti-cancer chemotherapeutic drugs, being widely used for the treatment of solid tumors and acute leukemias. The action of doxorubicin and other anthracycline drugs has been intensively investigated during the last several decades, but the mechanisms that have been proposed for cell killing remain disparate and controversial. In this review, we examine the proposed models for doxorubicin action from the perspective of the chromatin landscape, which is altered in many types of cancer due to recurrent mutations in chromatin modifiers. We highlight recent evidence for effects of anthracyclines on DNA torsion and chromatin dynamics that may underlie basic mechanisms of doxorubicin-mediated cell death and suggest new therapeutic strategies for cancer treatment. PMID:24361676

  4. Investigation of Torsional Oscillations in Railway Vehicles

    Directory of Open Access Journals (Sweden)

    Fridrichovský Tomáš

    2016-01-01

    Full Text Available The development of semiconductor electro-technics during last decades allowed us to produce railway vehicles with very high tractive power. High performances reveal new problems that were unknown until these days. One of these problems are torsional oscillations of running wheelsets, which may appear and compromise the safety of railway vehicles. This article analyzes dynamical events that may occur in drives of the vehicles and that are bound with transmission of the torque to the wheels during the operation of the vehicle, which is exposed to the variable external influences (adhesion conditions, track irregularities, variation of wheel forces, etc.. This is based on the idea of a model of simplified drive of the real railway vehicle, which is used for simulation purposes. The model serves for the parametric analysis of individual components, to make an effective design or control remedy.

  5. [Torsion and necrosis of epiploic appendices of the large bowel].

    Science.gov (United States)

    Timofeev, M E; Fedorov, E D; Krechetova, A P; Shapoval'iants, S G

    2014-01-01

    The features of the clinical symptoms was studied, the possibility of laparoscopy in modern diagnosis and treatment of epiploic appendices torsion and necrosis of the large bowel was assessed in the article. It was done the retrospective analysis of the medical records of 87 patients with a diagnosis of epiploic appendices torsion and necrosis of the large bowel. The patients had laparoscopic operations in our hospital in the period from January 1995 to December 2012. The clinical picture, laboratory and instrumental datas in cases of epiploic appendices torsion and necrosis were scarce and nonspecific. An abdominal pain preferentially localized in the lower divisions was the main symptom (97.7%). The instrumental methods did not allow to diagnose the torsion and necrosis of epiploic appendices in the majority of cases and all these techniques were used for the differential diagnosis with other diseases. The assumption of the presence of appendices torsion and necrosis occured just in 34.5% of cases before the operation. Diagnosis of epiploic appendices torsion and necrosis present significant difficulties on prehospital and preoperative stages. The diagnostic laparoscopy is the method of choice in unclear situations and it allows to diagnose the torsion and necrosis of epiploic appendices in 96.6% of cases. Successful surgical treatment by using laparoscopic approach is possible in 90.8% of cases.

  6. Analytical approach to calculate bending, longitudinal and torsional local stiffness of an asymmetric circumferential crack with contact condition

    Science.gov (United States)

    Sharafi, Mojtaba Meidan; Nikravesh, Majid Yadavar; Safarpour, Pedram

    2017-09-01

    In this paper, bending, longitudinal and torsional stiffness of an eccentric circumferential crack is investigated with taking into account contact condition on the crack surfaces based on fracture mechanics. Although several researches have analyzed stress intensity factors of symmetric circumferential crack, the stiffness of an asymmetric circumferential crack in different directions (along and perpendicular to eccentricity) regarding contact condition has not been studied by an analytical method until now. In this paper we aim to describe behavior of eccentric circumferential crack under axial loading and establish a relation between axial force and the resulting displacement vector. The twisting angle of asymmetric circumferential crack due to torsional loading is also calculated and compared to twisting angle of a symmetric crack. In order to simulate the local bending stiffness in the contact condition, nonlinear governing equations of bending stiffness associated to cracked beam section is developed by dividing it to strip elements and utilizing stiffness equations related to noncontact condition. It is validated by 3D finite element (FE) nonlinear model. Results show a significant compatibility between presented analytical and 3D FE methods. Moreover results of simulations show that without taking into account contact condition, axial, torsional and bending stiffness of symmetric and asymmetric circumferential crack are equal and radius of un-cracked area is the only influential factor.

  7. On the Torsion Units of Integral Adjacency Algebras of Finite Association Schemes

    Directory of Open Access Journals (Sweden)

    Allen Herman

    2014-01-01

    Full Text Available Torsion units of group rings have been studied extensively since the 1960s. As association schemes are generalization of groups, it is natural to ask about torsion units of association scheme rings. In this paper we establish some results about torsion units of association scheme rings analogous to basic results for torsion units of group rings.

  8. Torsion of a wandering spleen: an unusual abdominal catastrophe.

    Science.gov (United States)

    Riaz ul Haq, Muhammad; Elhassan, Elbagir; Mahdi, Diaa

    2014-11-01

    Wandering spleen is a rare clinical entity characterised by splenic hypermobility resulting from laxity or maldevelopment of the suspensory gastrosplenic, splenorenal, and phrenicocolic ligaments. Diagnosis is quite difficult, especially in children because of the lack of symptoms and signs until splenic torsion have occurred. An array of investigations is possible but US with color Doppler, CT with intravenous contrast and MRI are frequently being used to diagnose wandering spleen with or without torsion. We present a case of 5 years old child with torsion of wandering spleen to highlight the importance of prompt diagnosis and management.

  9. Gravitational Geometric Phase in the Presence of Torsion

    CERN Document Server

    Bakke, Knut; Nascimento, J R

    2008-01-01

    We investigate the relativistic and non-relativistic quantum dynamics of a neutral spin-1/2 particle submitted an external electromagnetic field in the presence of a cosmic dislocation. We analyze the explicit contribution of the torsion in the geometric phase acquired in the dynamic of this neutral spinorial particle. We discuss the influence of the torsion in the relativistic geometric phase. Using the Foldy-Wouthuysen approximation, the non-relativistic quantum dynamics are studied and the influence of the torsion in the Aharonov-Casher and He-McKellar-Wilkens effects are discussed.

  10. 5D Lovelock gravity: new exact solutions with torsion

    CERN Document Server

    Cvetković, B

    2016-01-01

    We investigate Lovelock gravity in five dimensions in first order formalism. We construct a new class of solutions: BTZ black ring with(out) torsion. We show that our solution with torsion exists in the different sector of the Lovelock gravity compared to Lovelock Chern-Simons and the sector investigated by Canfora et al. We compute conserved charges of the solutions by using Nester's formula, and confirm the results by canonical method. We show that the theory linearized around the background with torsion possesses additional degrees of freedom compared to general relativity.

  11. Critical current degradation behaviour of GdBCO CC tapes in pure torsion and combined tension-torsion modes

    Science.gov (United States)

    Gorospe, Alking; Bautista, Zhierwinjay; Shin, Hyung-Seop

    2016-10-01

    Coated conductor (CC) tapes utilized in high-current-density superconducting cables are commonly subjected to different loading modes, primarily torsion and tension especially in the case of twisted stacked-tape cable. Torsion load can occur due to twisting along the length or when winding the CC tapes around a former, while tension load can occur due to pre-tension when coiled and as a hoop stress when the coil is energized. In this study, electromechanical properties of single CC tapes under torsion load were investigated using a new test apparatus. The results could provide basic information for cable designers to fully characterize stacked cables. Copper-electroplated and brass-laminated CC tapes fabricated with different deposition techniques were subjected to pure torsion and combined tension-torsion loading. The critical current, I c degradation behaviours of CC tapes under torsional deformation were examined. Also, the effect of further external lamination on the I c degradation behaviour of the CC tapes under such loading conditions was investigated. In the case of the combined tension-torsion test, short samples were subjected to twist pitches of 200 mm and 100 mm. Critical parameters including reversible axial stress and strain in such twist pitch conditions were also investigated.

  12. Random gust response statistics for coupled torsion-flapping rotor blade vibrations.

    Science.gov (United States)

    Gaonkar, G. H.; Hohenemser, K. H.; Yin, S. K.

    1972-01-01

    An analysis of coupled torsion-flapping rotor blade vibrations in response to atmospheric turbulence revealed that at high rotor advance ratios anticipated for future high speed pure or convertible rotorcraft both flapping and torsional vibrations can be severe. While appropriate feedback systems can alleviate flapping, they have little effect on torsion. Dynamic stability margins have also no substantial influence on dynamic torsion loads. The only effective means found to alleviate turbulence caused torsional vibrations and loads at high advance ratio was a substantial torsional stiffness margin with respect to local static torsional divergence of the retreating blade.

  13. Protective effect of sildenafil citrate on contralateral testis injury after unilateral testicular torsion/detorsion

    OpenAIRE

    Yíldíz,Hamit; Durmus, Ali Said; Şimşek,Halil; Yaman, Mine

    2011-01-01

    OBJECTIVES: This study was designed to investigate prevention of contralateral testicular injury with sildenafil citrate after unilateral testicular torsion/detorsion. METHODS: Thirty-seven adult male rats were divided into four groups: sham operated (group 1, n = 7), torsion/detorsion + saline (group 2, n = 10), torsion/detorsion + 0.7 mg of sildenafil citrate (group 3, n = 10) and torsion/detorsion + 1.4 mg of sildenafil citrate (group 4, n = 10). Unilateral testicular torsion was created b...

  14. The dynamics and excitation of torsional waves in geodynamo simulations

    CERN Document Server

    Teed, Robert J; Tobias, Steven M

    2013-01-01

    The predominant force balance in rapidly rotating planetary cores is between Coriolis, pressure, buoyancy and Lorentz forces. This magnetostrophic balance leads to a Taylor state where the spatially averaged azimuthal Lorentz force is compelled to vanish on cylinders aligned with the rotation axis. Any deviation from this state leads to a torsional oscillation, signatures of which have been observed in the Earth's secular variation and are thought to influence length of day variations via angular momentum conservation. In order to investigate the dynamics of torsional oscillations, we perform several three-dimensional dynamo simulations in a spherical shell. We find torsional oscillations, identified by their propagation at the correct Alfv\\'{e}n speed, in many of our simulations. We find that the frequency, location and direction of propagation of the waves are influenced by the choice of parameters. Torsional waves are observed within the tangent cylinder and also have the ability to pass through it. Severa...

  15. Outcomes of Surgery for Posterior Polar Cataract Using Torsional Ultrasound

    Directory of Open Access Journals (Sweden)

    Selçuk Sızmaz

    2013-10-01

    Full Text Available Purpose: The aim of this study is to report outcomes of surgery for posterior polar cataract using torsional ultrasound. Material and Method: Medical records of 26 eyes of 21 consecutive patients with posterior polar cataract who had cataract surgery using the torsional phacoemulsification were evaluated retrospectively. The surgical procedure used, phacoemulsification parameters, intraoperative complications, and postoperative visual outcome were recorded. Results: Of the 26 eyes, 24 (92.3% had small to medium posterior polar opacity. Two eyes had large opacity. All surgeries were performed using the torsional handpiece. Posterior capsule rupture occurred in 4 (15.3% eyes. The mean visual acuity improved significantly after surgery (p<0.001. The postoperative visual acuity was worse than 20/20 in 5 eyes. The cause of the low acuity was amblyopia. Discussion: Successful surgical results and good visual outcome can be achieved with phacoemulsification using the torsional handpiece. (Turk J Ophthalmol 2013; 43: 345-7

  16. Behavior of the SU(2)-Reidemeister torsion form by mutation

    CERN Document Server

    Dubois, Jerome

    2012-01-01

    In this paper, we prove that the Reidemeister torsion twisted by the adjoint representation, which is considered as a 1-form, on the SU(2)-character variety of a knot exterior is invariant under mutation along a Conway sphere.

  17. Spin-torsion effects in the hyperfine structure of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Coudert, L. H., E-mail: laurent.coudert@lisa.u-pec.fr; Gutlé, C. [Laboratoire Inter-Universitaire des Systèmes Atmosphériques, UMR 7583 CNRS-Universités Paris Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex (France); Huet, T. R. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR 8523 CNRS-Université Lille 1, Bâtiment P5, 59655 Villeneuve d’Ascq Cedex (France); Grabow, J.-U. [Institut für Physikalische Chemie, Callinstrasse 3–3a, 30167 Hannover (Germany); Levshakov, S. A. [St. Petersburg Electrotechnical University “LETI,” 197376 St. Petersburg (Russian Federation)

    2015-07-28

    The magnetic hyperfine structure of the non-rigid methanol molecule is investigated experimentally and theoretically. 12 hyperfine patterns are recorded using molecular beam microwave spectrometers. These patterns, along with previously recorded ones, are analyzed in an attempt to evidence the effects of the magnetic spin-torsion coupling due to the large amplitude internal rotation of the methyl group [J. E. M. Heuvel and A. Dymanus, J. Mol. Spectrosc. 47, 363 (1973)]. The theoretical approach setup to analyze the observed data accounts for this spin-torsion in addition to the familiar magnetic spin-rotation and spin-spin interactions. The theoretical approach relies on symmetry considerations to build a hyperfine coupling Hamiltonian and spin-rotation-torsion wavefunctions compatible with the Pauli exclusion principle. Although all experimental hyperfine patterns are not fully resolved, the line position analysis yields values for several parameters including one describing the spin-torsion coupling.

  18. Isolated adnexal torsion in a 20-week spontaneous twin pregnancy

    Directory of Open Access Journals (Sweden)

    Ilker Kahramanoglu

    2016-01-01

    Discussion: Adnexal torsion as a cause of acute abdomen may be kept in mind in pregnants, even if there is no predisposing factor. Laparoscopy may be performed safely in 2nd trimester for acute abdomen.

  19. Two-step spacetime deformation-induced dynamical torsion

    Energy Technology Data Exchange (ETDEWEB)

    Ter-Kazarian, G, E-mail: gago-50@yahoo.com [Byurakan Astrophysical Observatory, Byurakan 378433, Aragatsotn District (Armenia)

    2011-03-07

    We extend the geometrical ideas of the spacetime deformations to study the physical foundation of the post-Riemannian geometry. To this aim, we construct the theory of two-step spacetime deformation as a guiding principle. We address the theory of teleparallel gravity and construct a consistent Einstein-Cartan (EC) theory with the dynamical torsion. We show that the equations of the standard EC theory, in which the equation defining torsion is the algebraic type and, in fact, no propagation of torsion is allowed, can be equivalently replaced by the set of modified EC equations in which the torsion, in general, is dynamical. The special physical constraint imposed upon the spacetime deformations yields the short-range propagating spin-spin interaction.

  20. Two-step spacetime deformation induced dynamical torsion

    CERN Document Server

    Ter-Kazarian, G

    2011-01-01

    We extend the geometrical ideas of the spacetime deformations to study the physical foundation of the post-Riemannian geometry. To this aim, we construct the theory of 'two-step spacetime deformation' as a guiding principle. We address the theory of teleparallel gravity and construct a consistent Einstein-Cartan (EC) theory with the 'dynamical torsion'. We show that the equations of the standard EC theory, in which the equation defining torsion is the algebraic type and, in fact, no propagation of torsion is allowed, can be equivalently replaced by the set of 'modified EC equations' in which the torsion, in general, is dynamical. The special physical constraint imposed upon the spacetime deformations yields the short-range propagating spin-spin interaction.

  1. The Torsion Theory Generated by M-Small Modules

    Institute of Scientific and Technical Information of China (English)

    A.(C)i(g)dem (O)zcan; Abdullah Harmanci

    2003-01-01

    Let M be a right R-module, M the class of all M-small modules,and P a projective cover of M in σ[M]. We consider the torsion theories TM =(TM,FM), TV = (TV,FV), and TP = (TP,FP) in σ[M], where TM is the torsion theory generated by M, TV is the torsion theory cogenerated by M, and TP is the dual Lambek torsion theory. We study some conditions for TM to be cohereditary,stable, or split, and prove that Rej(M, M) = M (→) FP = M (= TM = FV) (→)TP = TV (→) GenM(P) (∩-) TV.

  2. Quantization of Two-Dimensional Gravity with Dynamical Torsion

    CERN Document Server

    Lavrov, P M

    1999-01-01

    We consider two-dimensional gravity with dynamical torsion in the Batalin - Vilkovisky and Batalin - Lavrov - Tyutin formalisms of gauge theories quantization as well as in the background field method.

  3. M-theory moduli spaces and torsion-free structures

    CERN Document Server

    Graña, Mariana

    2014-01-01

    Motivated by the description of $\\mathcal{N}=1$ M-theory compactifications to four-dimensions given by Exceptional Generalized Geometry, we propose a way to geometrize the M-theory fluxes by appropriately relating the compactification space to a higher-dimensional manifold equipped with a torsion-free structure. As a non-trivial example of this proposal, we construct a bijection from the set of $Spin(7)$-structures on an eight-dimensional $S^{1}$-bundle to the set of $G_{2}$-structures on the base space, fully characterizing the $G_{2}$-torsion clases when the total space is equipped with a torsion-free $Spin(7)$-structure. Finally, we elaborate on how the higher-dimensional manifold and its moduli space of torsion-free structures can be used to obtain information about the moduli space of M-theory compactifications.

  4. M-theory moduli spaces and torsion-free structures

    Science.gov (United States)

    Graña, Mariana; Shahbazi, C. S.

    2015-05-01

    Motivated by the description of M-theory compactifications to four-dimensions given by Exceptional Generalized Geometry, we propose a way to geometrize the M-theory fluxes by appropriately relating the compactification space to a higher-dimensional manifold equipped with a torsion-free structure. As a non-trivial example of this proposal, we construct a bijection from the set of Spin(7)-structures on an eight-dimensional S 1-bundle to the set of G 2-structures on the base space, fully characterizing the G 2-torsion clases when the total space is equipped with a torsion-free Spin(7)-structure. Finally, we elaborate on how the higher-dimensional manifold and its moduli space of torsion-free structures can be used to obtain information about the moduli space of M-theory compactifications.

  5. Diffusion-weighted imaging findings of adnexal torsion: Initial results

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Shinya, E-mail: sfujii@grape.med.tottori-u.ac.jp [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, Tottori 683-8504 (Japan); Kaneda, Sachi; Kakite, Suguru; Kanasaki, Yoshiko; Matsusue, Eiji [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, Tottori 683-8504 (Japan); Harada, Tasuku [Division of Reproductive-Perinatal Medicine and Gynecological Oncology, Department of Surgery, Faculty of Medicine, Tottori University, Yonago (Japan); Kaminou, Toshio; Ogawa, Toshihide [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, Tottori 683-8504 (Japan)

    2011-02-15

    Our purpose is to clarify the diffusion-weighted (DW) imaging findings of adnexal torsion. We retrospectively analyzed the DW imaging findings in 11 consecutive patients with surgical confirmation of adnexal torsion. We assessed signal intensity of the adnexal mass and fallopian tube thickening, and the location of abnormal signal intensity within the adnexal mass. On DW imaging, thickening of the fallopian tube was apparent as abnormal signal intensity in 8 of 11 patients. Abnormal signal intensity was inhomogeneous in 7 of 8 patients. Abnormal signal intensity on DW imaging was observed in 10 of 11 adnexal masses, and in the walls of 7 out of 8 adnexal cystic lesions. In adnexal torsion, DW imaging showed abnormal signal intensity in the thickened fallopian tube and in the wall of cystic ovarian lesions. These findings would be feasible to diagnose adnexal torsion.

  6. experimental and analytical comparison of torsion, bending moment ...

    African Journals Online (AJOL)

    HOD

    AND SHEAR FORCES IN REINFORCED CONCRETE BEAMS USING BS 8110, EURO CODE. 2 AND ACI 318 ... In structural analysis and design, the effects of torsion are usually ... is fairly complex, owing to non-homogeneous, non-linear.

  7. Considerations on the Sp\\"orer-diagram - torsional wave relationship

    CERN Document Server

    Muraközy, J

    2014-01-01

    Studies on the earlier reported spatial correlations between magnetic field distributions and the torsional wave have been substantially extended to the period 1975-2009. The investigations are based on Debrecen sunspot data and magnetic field data of Mount Wilson. The recently available data and distributions seem to support the idea that the torsional wave may be caused by flows around the toruses which result in Coriolis-deviations forward and backward, establishing the prograde and retrograde belts.

  8. Anomalous pressure dependence of the torsional levels in solid nitromethane

    Science.gov (United States)

    Cavagnat, D.; Magerl, A.; Vettier, C.; Anderson, I. S.; Trevino, S. F.

    1985-01-01

    Inelastic neutron-scattering measurement of the torsional levels of CH3NO2 and CD3NO2 are presented as functions of pressure and temperature. In contrast to all previously observed pressure dependence of hindered rotors, the ground-state tunnel splitting increases and the energies of the bound torsional levels decrease with pressure. A potential which reproduces these anomalous effects is found and the source of the anomaly explained.

  9. Abnormalities of Penile Curvature: Chordee and Penile Torsion

    OpenAIRE

    2011-01-01

    Congenital chordee and penile torsion are commonly observed in the presence of hypospadias, but can also be seen in boys with the meatus in its orthotopic position. Varying degrees of penile curvature are observed in 4–10% of males in the absence of hypospadias. Penile torsion can be observed at birth or in older boys who were circumcised at birth. Surgical management of congenital curvature without hypospadias can present a challenge to the pediatric urologist. The most widely used surgical ...

  10. Torsion Points on an Algebraic Subset of an Affine Torus

    CERN Document Server

    Hironaka, E

    1996-01-01

    Work of Laurent and Sarnak, following a conjecture of Lang, shows that the number of torsion points of order n on an algebraic subset of an affine complex torus is polynomial periodic. In this paper, we find bounds on the degree and period of this number as a function of n. Some examples, including the number of n torsion points on Fermat curves, are computed to illustrate the methods.

  11. Muscular Basis of Whisker Torsion in Mice and Rats.

    Science.gov (United States)

    Haidarliu, Sebastian; Bagdasarian, Knarik; Shinde, Namrata; Ahissar, Ehud

    2017-09-01

    Whisking mammals move their whiskers in the rostrocaudal and dorsoventral directions with simultaneous rolling about their long axes (torsion). Whereas muscular control of the first two types of whisker movement was already established, the anatomic muscular substrate of the whisker torsion remains unclear. Specifically, it was not clear whether torsion is induced by asymmetrical operation of known muscles or by other largely unknown muscles. Here, we report that mystacial pads of newborn and adult rats and mice contain oblique intrinsic muscles (OMs) that connect diagonally adjacent vibrissa follicles. Each of the OMs is supplied by a cluster of motor end plates. In rows A and B, OMs connect the ventral part of the rostral follicle with the dorsal part of the caudal follicle. In rows C-E, in contrast, OMs connect the dorsal part of the rostral follicle to the ventral part of the caudal follicle. This inverse architecture is consistent with previous behavioral observations [Knutsen et al.: Neuron 59 (2008) 35-42]. In newborn mice, torsion occurred in irregular single twitches. In adult anesthetized rats, microelectrode mediated electrical stimulation of an individual OM that is coupled with two adjacent whiskers was sufficient to induce a unidirectional torsion of both whiskers. Torsional movement was associated with protracting movement, indicating that in the vibrissal system, like in the ocular system, torsional movement is mechanically coupled to horizontal and vertical movements. This study shows that torsional whisker rotation is mediated by specific OMs whose morphology and attachment sites determine rotation direction and mechanical coupling, and motor innervation determines rotation dynamics. Anat Rec, 300:1643-1653, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  12. A Numerical Model for Torsion Analysis of Composite Ship Hulls

    Directory of Open Access Journals (Sweden)

    Ionel Chirica

    2012-01-01

    Full Text Available A new methodology based on a macroelement model proposed for torsional behaviour of the ship hull made of composite material is proposed in this paper. A computer program has been developed for the elastic analysis of linear torsion. The results are compared with the FEM-based licensed soft COSMOS/M results and measurements on the scale simplified model of a container ship, made of composite materials.

  13. ESTIMATING TORSION OF DIGITAL CURVES USING 3D IMAGE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Christoph Blankenburg

    2016-04-01

    Full Text Available Curvature and torsion of three-dimensional curves are important quantities in fields like material science or biomedical engineering. Torsion has an exact definition in the continuous domain. However, in the discrete case most of the existing torsion evaluation methods lead to inaccurate values, especially for low resolution data. In this contribution we use the discrete points of space curves to determine the Fourier series coefficients which allow for representing the underlying continuous curve with Cesàro’s mean. This representation of the curve suits for the estimation of curvature and torsion values with their classical continuous definition. In comparison with the literature, one major advantage of this approach is that no a priori knowledge about the shape of the cyclic curve parts approximating the discrete curves is required. Synthetic data, i.e. curves with known curvature and torsion, are used to quantify the inherent algorithm accuracy for torsion and curvature estimation. The algorithm is also tested on tomographic data of fiber structures and open foams, where discrete curves are extracted from the pore spaces.

  14. Torsional Vibration of a Shafting System under Electrical Disturbances

    Directory of Open Access Journals (Sweden)

    Ling Xiang

    2012-01-01

    Full Text Available Torsional vibration responses of a nonlinear shafting system are studied by a modified Riccati torsional transfer matrix combining with the Newmark-β method. Firstly, the system is modeled as a chain consisting of an elastic spring with concentrated mass points, from which a multi-segment lumped mass model is established. Secondly, accumulated errors are eliminated from the eigenfrequencies and responses of the system's torsional vibration by this newly developed procedure. The incremental transfer matrix method, combining the modified Riccati torsional transfer matrix with Newmark-β method, is further applied to solve the dynamical equations for the torsional vibration of the nonlinear shafting system. Lastly, the shafting system of a turbine-generator is employed as an illustrating example, and simulation analysis has been performed on the transient responses of the shaft's torsional vibrations during typical power network disturbances, such as three-phase short circuit, two-phase short circuit and asynchronous juxtaposition. The results validate the present method and are instructive for the design of a turbo-generator shaft.

  15. Flexural-torsional buckling behavior of aluminum alloy beams

    Institute of Scientific and Technical Information of China (English)

    Xiaonong GUO; Zhe XIONG; Zuyan SHEN

    2015-01-01

    This paper presents an investigation on the flexural-torsional buckling behavior of aluminum alloy beams (AAB). First, based on the tests of 14 aluminum alloy beams under concentrated loads, the failure pattern, load- deformation curves, bearing capacity and flexural-torsional buckling factor are studied. It is found that all the beam specimens collapsed in the flexuml-torsional buckling with excessive deformation pattern. Moreover, the span, loading location and slenderness ratio influence the flexural-torsional buckling capacity of beams significantly. Secondly, besides the experiments, a finite element method (FEM) analysis on the flexural-torsional buckling behavior of AAB is also conducted. The main parameters in the FEM analysis are initial imperfection, material property, cross-section and loading scheme. According to the analytical results, it is indicated that the FEM is reasonable to capture mechanical behavior of AAB. Finally, on the basis of the experimental and analytical results, theoretical formulae to estimate the flexural- torsional buckling capacity of AAB are proposed, which could improve the application of present codes for AAB.

  16. Thermal conductivity and torsional oscillations of solid 4He

    Science.gov (United States)

    Brazhnikov, M. Yu.; Zmeev, D. E.; Golov, A. I.

    2012-11-01

    Polycrystalline samples of hcp 4He of molar volume Vm = 19.5 cm3 with small amount of 3He impurities were grown in an annular container by the blocked-capillary method. Three concentrations of 3He, x3, were studied: isotopically purified 4He with the estimated x3 dummy bob of the double-frequency torsional oscillator. The analysis of the frequency shifts upon loading with helium and changing temperatures of different parts of the oscillator suggests that the three techniques probe the properties of solid helium in three different locations: the two different torsion modes respond to the changes of the shear modulus of solid helium in either of the two torsion rods while the thermal conductivity probes the phonon mean free path in solid helium inside the annular container. The temperature and width of the torsional anomaly increase with increasing frequency and x3. The phonon mean free path increases with increasing x3. Annealing typically resulted in an increased phonon mean free path but often in little change in the torsional oscillator response. While the magnitude of the torsional anomaly and phonon mean free path can be very different in different samples, no correlation was found between them.

  17. Torsion as a Dark Matter Candidate from the Higgs Portal

    CERN Document Server

    Belyaev, Alexander S; Thomas, Marc C

    2016-01-01

    Torsion is a metric-independent component of gravitation, which may provide a more general geometry than the one taking place within general relativity. On the other hand torsion could lead to interesting phenomenology in both particle physics and cosmology. In the present work it is shown that a torsion field interacting with the SM Higgs doublet and having a negligible coupling to SM fermions is protected from decaying by a $Z_2$ symmetry, and therefore becomes a promising Dark Matter (DM) candidate. In order to check the consistency of this scenario we evaluate the DM relic density and explore direct DM detection and collider constraints on this model. It turns out that in the model when the Higgs boson is only partly responsible for the generation of torsion mass, there is a region of parameter space where torsion contributes 100% to the DM budget of the Universe. Furthermore, we show that the LHC currently has a limited sensitivity to the torsion parameter space via mono-jet signature and will be able to...

  18. Bicavitary effusion secondary to liver lobe torsion in a dog

    Directory of Open Access Journals (Sweden)

    Khan Z

    2016-04-01

    Full Text Available Zaheda Khan,1 Kathryn Gates,2 Stephen A Simpson,31Emergency and Critical Care, Animal Specialty and Emergency Center, Los Angeles, CA, 2Emergency and Critical Care, Advanced Critical Care, Emergency and Specialty Services, Culver City, CA 3Emergency and Critical Care, Southern California Veterinary Specialty Hospital, Irvine, CA, USA Abstract: We described the diagnosis and successful treatment of pleural and peritoneal effusion secondary to liver lobe torsion in a dog. A 12-year-old female spayed Borzoi dog was referred for heart failure. Emergency room thoracic and abdominal ultrasound showed a large volume of pleural effusion with mild peritoneal effusion and an abdominal mass. Pleural fluid analysis classified the effusion as exudative. A complete ultrasound revealed mild peritoneal effusion and decreased blood flow to the right liver lobe. Other causes of bicavitary effusion were ruled out based on blood work, ultrasound, echocardiogram, and computed tomography. The patient was taken to surgery and diagnosed with caudate liver lobe torsion and had a liver lobectomy. At the 2-week postoperative recheck, the patient was doing well and there was complete resolution of the pleural effusion. Liver lobe torsion is a rare occurrence in dogs and can be difficult to diagnose. Clinical signs are nonspecific for liver lobe torsion and patients may present in respiratory distress with significant pleural fluid accumulation. When assessing patients with pleural and peritoneal effusion, liver lobe torsion should be considered as a differential diagnosis.Keywords: pleural effusion, peritoneal effusion, hepatic torsion

  19. Numerical Analysis of Stress and Strain in Specimens with Rectangular Cross-Section Subjected to Torsion and Bending with Torsion

    Directory of Open Access Journals (Sweden)

    Faszynka Sebastian

    2016-03-01

    Full Text Available The paper presents an analysis of the state of stress and crack tip opening displacement (strain in specimens with rectangular cross-section subjected to torsion and combined bending with torsion. The specimens were made of the EN AW-2017A aluminium alloy. The specimens had an external unilateral notch, which was 2 mm deep and its radius was 22.5 mm. The tests were performed at constant moment amplitude MT = MBT = 15.84 N·m and under stress ratio R = −1. The exemplary results of numerical computations being obtained by using the FRANC3D software were shown in the form of stress and crack tip opening displacement (CTOD maps. The paper presents the differences of fatigue cracks growth under torsion and bending with torsion being derived by using the FRANC3D software.

  20. The protective role of erdosteine on testicular tissue after testicular torsion and detorsion.

    Science.gov (United States)

    Koc, Ahmet; Narci, Adnan; Duru, Mehmet; Gergerlioglu, H Serdar; Akaydin, Yesim; Sogut, Sadik

    2005-12-01

    Testicular torsion and detorsion are important clinical problems for infertile man and oxidative stress may have a role in this clinical situation. The aim of this study was to investigate the protective role of erdosteine, an antioxidant, on unilateral testicular reperfusion injury in rats. The rats were divided into four groups including seven rats in each group: control, torsion, torsion/detorsion and torsion/detorsion+erdosteine. Rats, except the sham operation group, were subjected to left unilateral torsion (720( composite function) rotation in the clockwise direction) without including the epididymis. The experiments were finished after sham operation time for control, 120 min torsion for torsion group and 120 min torsion and 240 min detorsion for torsion/detorsion groups. Bilateral orchiectomy was performed for all groups of rats. The ipsilateral and controlateral testis were divided into two pieces to analyse biochemical parameters and to investigate the light microscopic view. Malondialdehyde level of ipsilateral testis was increased in torsion and torsion/detorsion groups in comparison with the other groups (p Erdosteine treatment ameliorated lipid peroxidation after torsion/detorsion in ipsilateral testis (p Erdosteine treatment caused increased glutathione peroxidase activity in comparison with torsion and torsion/detorsion groups and catalase activity in comparison with the other groups in ipsilateral testis (p erdosteine groups than control and torsion groups (p erdosteine groups showed ipsilateral testicular damage in the histological examination, but the specimens from torsion/detorsion had a significantly greater histological injury than those from the other groups (p erdosteine group, the testicular tissues were affected with slight-to-moderate degenerative changes of the seminiferous epithelium. Administration of erdosteine resulted in a significantly reduced histological damage associated with torsion of the spermatic cord compared with torsion

  1. Design, Development and Scaling Analysis of a Variable Stiffness Magnetic Torsion Spring

    Directory of Open Access Journals (Sweden)

    Angelo Sudano

    2013-10-01

    Full Text Available In this paper we report on the design, modeling, experimental testing and scaling analysis of a novel MAgnetic Variable stiffnEess spRIng-Clutch (MAVERIC device, which may be used as the elastic element of Variable Stiffness Actuators (VSAs. The device, comprising two co-axial diametrically magnetized hollow cylinders, has two degrees of freedom: a rotation of the two cylinders around the common axis and a relative translation along the same axis. For small rotations, the torque arising from the magnetic interaction of the two cylinders is almost linearly proportional to their relative rotation, as in mechanical torsion springs. In addition, the stiffness of the equivalent spring can be varied continuously from a maximum value down to exactly zero by changing the axial overlap of the two cylinders. In this way the proposed device can be used both as a clutch (i.e., perfectly compliant element and as a variable stiffness torsion spring. A prototype, designed after magnetostatic FEM simulations, has been built and experimentally characterized. The developed MAVERIC has an experimentally determined maximum transmissible torque of 109.81mNm, while the calculated maximum stiffness is 110.2mNmrad−1. The amplitude of the torque-angle characteristic can be tuned linearly with a sensitivity of 12.63mNmmm−1 rad−1. Further simulations have been computed parameterizing the geometry and the number of pole pairs of the magnets. The maximum torque density reached for one pole pair is 47.21 · 103 Nm m−3, whereas for a fixed geometry similar to that of the developed prototype, the maximum torque is reached for seven pole pairs. Overall, compared to mechanical springs, MAVERIC has no fatigue or overloading issues. Compared to other magnetic couplers, torsion stiffness can be varied continuously from a maximum value down to exactly zero, when the device acts as a disengaged clutch, disconnecting the load from the actuator.

  2. Magnetic resonance imaging findings in adnexial torsion

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, Ronald Meira Castro; Quadros, Marianne Siquara de [Hospital Albert Einstein, Sao Paulo, SP (Brazil). Instituto de Ensino e Pesquisa], e-mail: rtrindade@einstein.br; Baroni, Ronaldo Hueb; Rosemberg, Michelle; Racy, Marcelo de Castro Jorge; Tachibana, Adriano [Hospital Albert Einstein, Sao Paulo, SP (Brazil); Funari, Marcelo Buarque de Gusmao [Hospital Albert Einstein, Sao Paulo, SP (Brazil). Imaging Service

    2010-01-15

    Adnexial torsion is an unusual event, but a major cause of abdominal pain in women. It is often associated with ovarian tumor or cyst, but can occur in normal ovaries, especially in children. The twisting of adnexial structures may involve the ovary or tube, but frequently affects both. In most cases, it is unilateral, with slight predilection for the right size. In imaging findings, increased ovarian volume and adnexial masses are observed, with reduced or absent vascularisation. In cases of undiagnosed or untreated complete twist, hemorrhagic necrosis may occur leading to complications; in that, peritonitis is the most frequent. Early diagnosis helps preventing irreversible damage with conservative treatment, thereby saving the ovary. Limitations in performing physical examination, possible inconclusive results in ultrasound and exposure to radiation in computed tomography makes magnetic resonance imaging a valuable tool in emergency assessment of gynecological diseases. The objective of this study was to report two confirmed cases of adnexial twist, emphasizing the contribution of magnetic resonance imaging in the diagnosis of this condition. (author)

  3. Failure Analysis of Aviation Torsional Springs

    Institute of Scientific and Technical Information of China (English)

    HOU Weiguo; ZHANG Weifang; LIU Xiao; WANG Zongren; DING Meili

    2011-01-01

    Cracks and fractures occur during the assembly process to a type of torsional springs used in the aviation mechanism.Besides visual examination,other experimental techniques used for the investigation are:1) fracture characteristics,damage morphology and ffactography by scanning electron microscopy(SEM),2) spectrum analysis of covering,3) metallographic observation of cracks and 4) hydrogen content testing.The results are obtained through the analysis of manufacture process and experimental data.Since no changes of microstructure are found,failures are irrelevant to the material.The cracks and fractures initiate on the inner surface,cracks initiate before the cadmium plating and after the winding.No obvious stress corrosion cracks are found near the crack source region.The opening direction of cracks is consistent with the residual tensile stress of the spring inner surface,and the springs are easy to contact hydrogen media between the spring winding and the cadmium plating.The cracks are caused by hydrogen-induced delayed cracking under the action of the residual tensile stress and hydrogen.

  4. DUPLEX: A molecular mechanics program in torsion angle space for computing structures of DNA and RNA

    Energy Technology Data Exchange (ETDEWEB)

    Hingerty, B.E.

    1992-07-01

    DUPLEX produces energy minimized structures of DNA and RNA of any base sequence for single and double strands. The smallest subunits are deoxydinucleoside monophosphates, and up to 12 residues, single or double stranded can be treated. In addition, it can incorporate NMR derived interproton distances an constraints in the minimizations. Both upper and lower bounds for these distances can be specified. The program has been designed to run on a UNICOS Cray supercomputer, but should run, albeit slowly, on a laboratory computer such as a VAX or a workstation.

  5. A new angle on the Euler angles

    Science.gov (United States)

    Markley, F. Landis; Shuster, Malcolm D.

    1995-01-01

    We present a generalization of the Euler angles to axes beyond the twelve conventional sets. The generalized Euler axes must satisfy the constraint that the first and the third are orthogonal to the second; but the angle between the first and third is arbitrary, rather than being restricted to the values 0 and pi/2, as in the conventional sets. This is the broadest generalization of the Euler angles that provides a representation of an arbitrary rotation matrix. The kinematics of the generalized Euler angles and their relation to the attitude matrix are presented. As a side benefit, the equations for the generalized Euler angles are universal in that they incorporate the equations for the twelve conventional sets of Euler angles in a natural way.

  6. Compensating for Torsion Windup in Steerable Needles

    Science.gov (United States)

    Reed, Kyle B.

    2010-01-01

    Long, flexible, bevel-tip needles curve during insertion into tissue, and rotations of the needle base reorient the tip to steer subsequent insertions. Friction between the tissue and the needle shaft, however, can cause a severe discrepancy between the needle base and tip angles. In this paper, I demonstrate an algorithm to properly align the entire length of the needle using torque measured at the base. My algorithm uses several intermediate base rotations to align the orientation of points along the shaft with the desired angle, with minimal remaining torque exerted by the base. I performed an experimental validation with four angle sensors attached to the needle throughout the tissue. My compensation algorithm decreased the lag throughout the needle by up to 88%. PMID:20640198

  7. Glaucoma, Open-Angle

    Science.gov (United States)

    ... Programs Home > Statistics and Data > Glaucoma, Open-angle Glaucoma, Open-angle Open-angle Glaucoma Defined In open-angle glaucoma, the fluid passes ... 2010 2010 U.S. Age-Specific Prevalence Rates for Glaucoma by Age and Race/Ethnicity The prevalence of ...

  8. Energy harvesting from a multifrequency response of a tuned bending-torsion system

    Science.gov (United States)

    Abdelkefi, A.; Nayfeh, A. H.; Hajj, M. R.; Najar, F.

    2012-07-01

    We investigate the benefits of tuning the frequencies of an energy harvester to extract more energy from a base excitation that comprises three frequency components. The energy harvester is composed of a unimorph cantilever beam with asymmetric tip masses. By adjusting the asymmetry of the tip masses, we can tune this beam-mass structure to harvest energy from multifrequency components of a base excitation. We model the beam using the Euler-Bernoulli beam theory and use the first three global mode shapes of the harvester in a Galerkin procedure to derive a reduced-order model describing its response. We derive an exact analytical solution for the tip deflection, twisting angle, voltage output, and harvested electrical power. Using this solution, we investigate the advantages of harvesting energy from a response that contains multifrequencies in comparison to a response that contains a single frequency by tuning only the fundamental frequency. The advantages of this bending-torsion energy harvester and the effect of its tuning are investigated for different short- and open-circuit configurations. The results show that, through a proper tuning of this bending-torsion harvester, the harvested power can be increased significantly and it can be made to cover a wide range of electrical load resistances.

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

    Science.gov (United States)

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

    2014-08-01

    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 α,α-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).

  10. Dynamic Finite Element Analysis of Extensional-Torsional Coupled Vibration in Nonuniform Composite Beams

    Science.gov (United States)

    Hashemi, Seyed M.; Roach, Andrew

    2011-12-01

    The application of a Dynamic Finite Element (DFE) technique to the extensional-torsional free vibration analysis of nonuniform composite beams, in the absence of flexural coupling, is presented. The proposed method is a fusion of the Galerkin weighted residual formulation and the Dynamic Stiffness Matrix (DSM) method, where the basis functions of approximation space are assumed to be the closed form solutions of the differential equations governing uncoupled extensional and torsional vibrations of the beam. The use of resulting dynamic trigonometric interpolation (shape) functions leads to a frequency dependent stiffness matrix, representing both mass and stiffness properties of the beam element. Assembly of the element matrices and the application of the boundary conditions then leads to a frequency dependent nonlinear eigenproblem, which is solved to evaluate the system natural frequencies and modes. Two illustrative examples of uniform and tapered cantilevered, Circumferentially Uniform Stiffness ( CUS), hollow, composite beams are presented. The influence of ply fibre-angle on the natural frequencies is also studied. The correctness of the theory and the superiority of the proposed DFE over the contrasting DSM and conventional FEM methods are confirmed by the published results and numerical checks. The discussion of results is followed by some concluding remarks.

  11. Torsional electric dipole moment functions calculated for HOOH and ClOOCl

    Science.gov (United States)

    McGrath, Mark P.

    2013-03-01

    The periodic torsional, electric dipole moment (EDM) functions μ(ϕ) = ∑m = 0pmcos (m + 1/2)ϕ, 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 μ(ϕ) 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 μ(ϕ) of ClOOCl, defined by μ(ϕ) = {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 (ϕ = 0) to the trans (ϕ = π) 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.

  12. Dynamical flexibility of torsionally vibrating mechatronic system

    Directory of Open Access Journals (Sweden)

    A. Buchacz

    2008-01-01

    Full Text Available Purpose: of this paper is the application of the approximate method called Galerkin’s method to solve the task of assigning the frequency-modal analysis and characteristics of a mechatronic system.Design/methodology/approach: was the formulated and solved as a problem in the form of a set of differential equations of the considered mechatronic model of an object. To obtain the solution, Galerkin’s method was used. The discussed torsionally vibrating mechatronic system consists of mechanical system, which is a continuous bar of circular cross-section, clamped on its ends. The electrical subsystem of the considered mechatronic system is a ring transducer to be perfectly bonded to the bar surface.Findings: this study is that the parameters of the transducer have an important influence on the values of natural frequencies and on the form of the characteristics of the said mechatronic system. The results of the calculations were not only presented in a mathematical form but also as transients of the examined dynamical characteristic which are a function of frequency of the assumed excitation.Research limitations/implications: is that the linear mechatronic system was considered, for this type of systems, such approach is sufficient.Practical implications: of this researches was that another approach is presented, that means in the domain of frequency spectrum analysis. The method used and the obtained results can be of some value for designers of mechatronic systems.Originality/value: of this paper is that the mechatronic system, created from mechanical and electrical subsystems with electromechanical bondage was examined. This approach is other than those considered elsewhere.

  13. Does a Randall-Sundrum scenario create the illusion of a torsion-free universe?

    CERN Document Server

    Mukhopadhyaya, B; Sen-Gupta, S; Mukhopadhyaya, Biswarup; Sen, Somasri; Gupta, Soumitra Sen

    2002-01-01

    We consider spacetime with torsion in a Randall-Sundrum (RS) 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.

  14. Torsional Behaviour and Finite Element Analysis of the Hybrid Laminated Composite Shafts: Comparison of VARTM with Vacuum Bagging Manufacturing Method

    Directory of Open Access Journals (Sweden)

    Mehmet Emin Taşdelen

    2016-01-01

    Full Text Available Braided sleeve composite shafts are produced and their torsional behavior is investigated. The braided sleeves are slid over an Al tube to create very strong and rigid tubular form shafts and they are in the form of 2/2 twill biaxial fiber fabric that has been woven into a continuous sleeve. Carbon and glass fibers braided sleeves are used for the fabrication of the composite shafts. VARTM (vacuum assisted resin transfer molding and Vacuum Bagging are the two different types of manufacturing methods used in the study. Torsional behaviors of the shafts are investigated experimentally in terms of fabrication methods and various composite materials parameters such as fiber types, layer thickness, and ply angles. Comparing the two methods in terms of the torque forces and strain angles, the shafts producing entirely carbon fiber show the highest torque capacities; however, considering the cost and performance criteria, the hybrid shaft made up of carbon and glass fibers is the optimum solution for average demanded properties. Additionally, FE (finite element model of the shafts was created and analyzed by using ANSYS workbench environment. Results of finite element analysis are compared with the values of twisting angle and torque obtained by experimental tests.

  15. Cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of V taper 2 and V taper 2H rotary NiTi files.

    Science.gov (United States)

    Chang, S W; Shim, K S; Kim, Y C; Jee, K K; Zhu, Q; Perinpanayagam, H; Kum, K Y

    2016-11-01

    The aim of this study was to compare the cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of conventional NiTi wire (V taper 2, V2) and CM wire (V taper 2H, V2H)-based files. Cyclic fatigue and torsional resistance of V2 and V2H were investigated by measuring the number of cycles to fracture, maximum torque at fracture, and maximum angle at fracture. The typical patterns of fatigue and torsional fractures were investigated using a scanning electron microscope (SEM). The metallurgical characteristics were investigated by differential scanning calorimetry (DSC) from -100 °C to 100 °C. The austenite finishing temperature (Af) of each instrument was also measured. The microstructures of the instruments were investigated by a transmission electron microscope (TEM) along with selected area diffraction pattern analysis. The results were statistically analyzed by Mann-Whitney U-test (p = 0.05). V2H showed significantly higher cyclic fatigue resistance and torsional resistance than V2. SEM images of the fractured surfaces showed typical patterns of fatigue and torsional fracture. The DSC analysis of V2 showed one small peak in both the heating and cooling curves. The Af of V2 was -0.32 °C. V2H showed two remarkable peaks in the heating curve and one remarkable peak in the cooling curve. The Af of V2H was 33.25 °C. The TEM analysis showed that both V2 and V2H are mainly composed of austenite. In conclusion, V2H showed higher cyclic fatigue resistance and torsional resistance than V2. The superior properties of V2H could be attributed to the annealing effect and possibly the martensite phase. SCANNING 38:564-570, 2016. © 2016 Wiley Periodicals, Inc.

  16. Resistance to torsional failure and cyclic fatigue resistance of ProTaper Next, WaveOne, and Mtwo files in continuous and reciprocating motion: An in vitro study

    Directory of Open Access Journals (Sweden)

    N O Varghese

    2016-01-01

    Full Text Available Aims: The purpose of this study was to evaluate the resistance to torsional failure and cyclic fatigue resistance of ProTaper Next (PTN, WaveOne, and Mtwo files in continuous and reciprocating motion. Settings and Design: Randomized control trial in a tertiary care setting. Subjects and Methods: A total of 10 new size 25.06 taper PTN X2, 25.06 taper Mtwo files, and 25.08 taper WaveOne primary files each was selected. A custom fabricated cyclic fatigue testing device with a 70° angle of curvature and 3 mm width; curvature starting at 6 mm from the tip was used. All instruments were rotated and reciprocated till fracture occurred and time till fracture of each instrument was recorded in seconds. For torsional failure testing 5 mm tip of each file was embedded in composite resin block and uniform torsional stresses (300 rpm, 2.0 Ncm were applied repetitively by an endodontic motor with auto stop mode until file succumbed to torsional failure. Number of load applications leading to failure was recorded. Statistical Analysis Used: Data were analyzed using t-test for equality of means, Pearson correlation, and ANOVA test. Results: All the files showed superior resistance to cyclic fatigue in reciprocating motion when compared with continuous rotation mode. WaveOne primary files displayed maximum resistance to cyclic fatigue both in continuous and reciprocating motion. WaveOne primary files also demonstrated maximum resistance to torsional failure followed by PTN with Mtwo files exhibiting least resistance. Conclusions: Operating files in reciprocating motion enhances their cyclic fatigue resistance. WaveOne files showed maximum resistance to cyclic fatigue and torsional failure due to their cross-sectional diameter coupled M-Wire technology.

  17. Quantum Chemical Calculations of Torsionally Mediated Hyperfine Splittings in States of E Symmetry of Acetaldehyde (CH_{3}CHO)

    Science.gov (United States)

    Xu, Li-Hong; Reid, Elias M.; Guislain, Bradley; Hougen, Jon T.; Alekseev, E. A.; Krapivin, Igor

    2017-06-01

    Hyperfine splittings in methanol have been revisited in three recent publications. (i) Coudert et al. [JCP 143 (2015) 044304] published an analysis of splittings observed in the low-J range. They calculated 32 spin-rotation, 32 spin-spin, and 16 spin-torsion hyperfine constants using the ACES2 package. Three of these constants were adjusted to fit hyperfine patterns for 12 transitions. (ii) Three present authors and collaborators [JCP 145 (2016) 024307] analyzed medium to high-J experimental Lamb-dip measurements in methanol and presented a theoretical spin-rotation explanation that was based on torsionally mediated spin-rotation hyperfine operators. These contain, in addition to the usual nuclear spin and overall rotational operators, factors in the torsional angle α of the form {e^{plusmn;{inα}}}. Such operators have non-zero matrix elements between the two components of a torsion-rotation ^{tr}E state, but have zero matrix elements within a ^{tr}A state. More than 55 hyperfine splittings were successfully fitted using three parameters and the fitted values agree well with ab initio values obtained in (i). (iii) Lankhaar et al. [JCP 145 (2016) 244301] published a reanalysis of the data set from (i), using CFOUR recalculated hyperfine constants based on their rederivation of the relevant expressions. They explain why their choice of fixed and floated parameters leads to numerical values for all parameters that seem to be more physical than those in (i). The results in (ii) raise the question of whether large torsionally-mediated spin-rotation splittings will occur in other methyl-rotor-containing molecules. This abstract presents ab initio calculations of torsionally mediated hyperfine splittings in the E states of acetaldehyde using the same three operators as in (ii) and spin-rotation constants computed by Gaussian09. We explored the first 13 K states for J from 10 to 40 and ν_{t} = 0, 1, and 2. Our calculations indicate that hyperfine splittings in CH_{3}CHO

  18. Stiffness matrix for beams with shear deformation and warping torsion

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, K.; Pilkey, W. [Univ. of Virginia, Charlottesville, VA (United States)

    1995-12-31

    A beam model which considers the warping effect in beams with arbitrary cross sections is discussed. This model takes into account bending, shear, and warping torsion. The derivation builds on a result in beam theory that, if shear is considered, for arbitrary cross sections the deflections in the different coordinate directions are not uncoupled as has been widely assumed. This conclusion follows from the calculation of the shear coefficients from an elasticity solution using an energy formulation. The shear coefficients form a symmetric tensor. The principal axes for this tensor are called principal shear axes. In Reference 2 structural matrices for the shear problem are derived using these shear coefficients. This paper extends these matrices to warping torsion. St. Venant`s semi-inverse method is applied to calculate warping shear stresses. The usual assumptions of the beam theory are made. The material is linear elastic. The loads may consist of shear forces, axial loads and twisting moments. Small deformations are considered. The cross section of the beam can be of arbitrary shape, thin-walled or solid. A deformation coefficient matrix is calculated which describes the relations between the deformations and the different load cases such as shear, torsion, and warping torsion. Numerical results for warping shear stresses and deformations are given. Also, a method to derive a stiffness matrix for a beam of arbitrary cross section under combined loading including warping torsion is presented.

  19. Autoparallel vs. Geodesic Trajectories in a Model of Torsion Gravity

    Directory of Open Access Journals (Sweden)

    Luis Acedo

    2015-11-01

    Full Text Available We consider a parametrized torsion gravity model for Riemann–Cartan geometry around a rotating axisymmetric massive body. In this model, the source of torsion is given by a circulating vector potential following the celestial parallels around the rotating object. Ours is a variant of the Mao, Tegmark, Guth and Cabi (MTGC model in which the total angular momentum is proposed as a source of torsion. We study the motion of bodies around the rotating object in terms of autoparallel trajectories and determine the leading perturbations of the orbital elements by using standard celestial mechanics techniques. We find that this torsion model implies new gravitational physical consequences in the Solar system and, in particular, secular variations of the semi-major axis of the planetary orbits. Perturbations on the longitude of the ascending node and the perihelion of the planets are already under discussion in the astronomical community, and if confirmed as truly non-zero effects at a statistically significant level, we might be at the dawn of an era of torsion phenomenology in the Solar system.

  20. Computed Tomography Appearance of Ovarian Fibrothecomas With and Without Torsion

    Energy Technology Data Exchange (ETDEWEB)

    Chee-Wai Mak; Wen-Sheng Tzeng; Chin-Yu Chen (Dept. of Diagnostic Imaging, Chi-Mei Medical Center, Yung Kang, Tainan, Taiwan (China))

    2009-06-15

    Background: Fibrothecomas are the most common solid ovarian tumors and may undergo torsion. Early diagnosis of these tumors is important in order to allow prompt surgical treatment. Purpose: To describe the features of ovarian fibrothecoma on computed tomography (CT) and to determine the possibility of detecting tumor torsion in this kind of tumor. Material and Methods: The CT images of 11 patients with ovarian fibrothecomas in the past 8 years at our hospital were retrospectively reviewed. The CT attenuation values of each tumor were measured in both non-enhanced and enhanced scans. The size and degree of enhancement were evaluated and correlated with tumor torsion. All cases were pathologically proven. Results: Three kinds of tumor pattern were found: 1) homogeneous tumor with significant enhancement containing scattered, low-attenuated regions after contrast injection; 2) heterogeneous tumor with mild enhancement after contrast injection; and 3) low-attenuated soft-tissue mass with no obvious enhancement after contrast injection. Conclusion: Fibrothecomas usually appear as a homogeneous solid tumor with varying degrees of enhancement. Calcification may be present and, as these tumors enlarge, myxoid or cystic degeneration may occur, resulting in a heterogeneous pattern. The larger the tumor, the greater is the chance of torsion. Lack of tumor enhancement is the most reliable sign for detection of ovarian torsion and should facilitate prompt surgical intervention to remove damaged tissue

  1. Torsion of the Retroperitoneal Kidney: Uncommon or Underreported?

    Directory of Open Access Journals (Sweden)

    Michael Sosin

    2014-01-01

    Full Text Available 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.

  2. Torsional and Bending Vibration Measurement on Rotors Using Laser Technology

    Science.gov (United States)

    MILES, T. J.; LUCAS, M.; HALLIWELL, N. A.; ROTHBERG, S. J.

    1999-09-01

    Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) was developed for non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. This paper describes comprehensive theory to account for the sensitivity of the LTV's measurements to shaft motion in all degrees of freedom. The optical geometry of the LTV offers inherent immunity to translational motion of the target shaft, either axial or radial. However, its measurements are sensitive to angular lateral vibration of the shaft. The significance of this sensitivity is compared with the instrument noise floor and typical torsional and lateral vibration levels. Optimum alignments of the instrument are then specified to ensure effective immunity to all lateral motion in typical applications. To overcome this problem more reliably, a new technique is proposed permitting unambiguous measurement of pure torsional vibration in situations where use of a single LTV demonstrates unacceptable sensitivity to angular lateral vibrations. Practical application of this technology is demonstrated with torsional vibration measurements from a diesel engine crankshaft. Simultaneously, previously unattained measurements of shaft bending vibration measurements are made. The first bending mode of the crankshaft was identified and its vibration amplitude and damping estimated. This application of laser vibrometry for non-contact measurements of shaft vibration represents a further step forward in the use of this technology for machinery diagnostics.

  3. Crack path in aeronautical titanium alloy under ultrasonic torsion loading

    Directory of Open Access Journals (Sweden)

    A. Nikitin

    2016-01-01

    Full Text Available This paper discusses features of fatigue crack initiation and growth in aeronautical VT3-1 titanium alloy under pure torsion loading in gigacycle regime. Two materials: extruded and forged VT3-1 titanium alloys were studied. Torsion fatigue tests were performed up to fatigue life of 109 cycles. The results of the torsion tests were compared with previously obtained results under fully reversed axial loading on the same alloys. It has been shown that independently on production process as surface as well subsurface crack initiation may appear under ultrasonic torsion loading despite the maximum stress amplitude located at the specimen surface. In the case of surface crack initiation, a scenario of crack initiation and growth is similar to HCF regime except an additional possibility for internal crack branching. In the case of subsurface crack, the initiation site is located below the specimen surface (about 200 μm and is not clearly related to any material flaw. Internal crack initiation is produced by shear stress in maximum shear plane and early crack growth is in Mode II. Crack branching is limited in the case of internal crack initiation compared to surface one. A typical ‘fish-eye’ crack can be observed at the torsion fracture surface, but mechanism of crack initiation seems not to be the same than under axial fatigue loading.

  4. Torsion as a dark matter candidate from the Higgs portal

    Science.gov (United States)

    Belyaev, Alexander S.; Thomas, Marc C.; Shapiro, Ilya L.

    2017-05-01

    Torsion is a metric-independent component of gravitation, which may provide a more general geometry than the one taking place within general relativity. On the other hand, torsion could lead to interesting phenomenology in both particle physics and cosmology. In the present work it is shown that a torsion field interacting with the SM Higgs doublet and having a negligible coupling to standard model (SM) fermions is protected from decaying by a Z2 symmetry, and therefore becomes a promising dark matter (DM) candidate. This model provides a good motivation for Higgs portal vector DM scenario. We evaluate the DM relic density and explore direct DM detection and collider constraints on this model to understand its consistency with experimental data and establish the most up-to-date limits on its parameter space. We have found in the model when the Higgs boson is only partly responsible for the generation of torsion mass, there is a region of parameter space where torsion contributes 100% to the DM budget of the Universe. Furthermore, we present the first results on the potential of the LHC to probe the parameter space of minimal scenario with Higgs portal vector DM using mono-jet searches and have found that LHC at high luminosity will be sensitive to the substantial part of model parameter space which cannot be probed by other experiments.

  5. Influence of geometry and materials on the axial and torsional strength of the head-neck taper junction in modular hip replacements: A finite element study.

    Science.gov (United States)

    Fallahnezhad, Khosro; Farhoudi, Hamidreza; Oskouei, Reza H; Taylor, Mark

    2016-07-01

    The assembly force is important in establishing the mechanical environment at the head-neck taper junction of modular hip replacements. Previous experimental results of the assembled taper junctions with different material combinations (Co-28Cr-6Mo and Ti-6Al-4V) reported similar axial strengths (pull-off loads), but lower torsional strengths (twist-off moments) for the CoCr/CoCr junction. However, mechanics of the junction and the strength behaviour have not been understood yet. A three dimensional finite element model of an isolated femoral head-neck junction was developed to explore the assembly and disassembly procedures, particularly the axial and torsional strengths for different material combinations and geometries. Under the same assembly load, the contacting length between the CoCr head and titanium neck was greater than that of in CoCr/CoCr. The contact length in the titanium neck was more sensitive to the assembly force when compared to the CoCr neck. For instance, with increasing the assembly force from 1890 to 3700N, the contact length increased by 88% for CoCr/Ti and 59% for CoCr/CoCr junctions. The torsional strength of the junction was related to the lateral deformation of the neck material due to the applied moment. The angular mismatch existing between the head and neck components was found to play the main role in the torsional strength of the junction. The smaller mismatch angle the higher torsional strength. It is suggested to consider reducing the mismatch angle, particularly in CoCr/CoCr junctions, and ensure a sufficiently high assembly force is applied by impaction for this combination.

  6. Torsional wave propagation in multiwalled carbon nanotubes using nonlocal elasticity

    Science.gov (United States)

    Arda, Mustafa; Aydogdu, Metin

    2016-03-01

    Torsional wave propagation in multiwalled carbon nanotubes is studied in the present work. Governing equation of motion of multiwalled carbon nanotube is obtained using Eringen's nonlocal elasticity theory. The effect of van der Waals interaction coefficient is considered between inner and outer nanotubes. Dispersion relations are obtained and discussed in detail. Effect of nonlocal parameter and van der Waals interaction to the torsional wave propagation behavior of multiwalled carbon nanotubes is investigated. It is obtained that torsional van der Waals interaction between adjacent tubes can change the rotational direction of multiwalled carbon nanotube as in-phase or anti-phase. The group and escape velocity of the waves converge to a limit value in the nonlocal elasticity approach.

  7. Early Universe Dynamos from Neutrino Oscillations Induced by Torsion

    CERN Document Server

    de Andrade, Garcia

    2016-01-01

    Earlier de Sabbata and Gasperini have shown that neutrinos oscillation which gives them a mass can be induced by torsion. More recently Enqvist et al have shown that it is possible to use massive neutrinos BBN magnetic fields to seed galactic magnetic fields. Thus based on these previous investigations we present several examples of how obtaining cosmological magnetic seed fields as galactic magnetic fields from massive neutrino densities and also from the torsion obtained by Nitsch as $T\\approx{10^{-24}s^{-1}}$ at the present day which yields magnetic seed field of the order of $B_{seed}\\approx{10^{-12}G}$. In the case we use torsion derived from massive neutrinos given by $T_{\

  8. A Case of Torsion of Gravid Uterus Caused by Leiomyoma

    Directory of Open Access Journals (Sweden)

    Gururaj Deshpande

    2011-01-01

    Full Text Available Uterine torsion during pregnancy is only sporadically reported in the literature. Here we present a case of leiomyoma causing uterine torsion in pregnancy and review the literature on etiology, diagnosis, and management. A 25-years-old primigravida with leiomyoma complicating pregnancy was admitted in our hospital with abdominal pain and uterine tenderness. She underwent emergency LSCS (lower segment cesarean section for fetal bradycardia. Intraoperatively, the uterus was rotated 180 degrees left to right. Inadvertent incision on the posterior wall was avoided by proper delineation of anatomy. Torsion was corrected by exteriorization of leiomyoma and uterus, and lower segment cesarean was carried out safely. Prompt recognition and management of this condition is necessary for better maternal and fetal outcome.

  9. Equation of State of Gravitational Scalar-Torsion Mode

    CERN Document Server

    Tseng, Huan-Hsin; Geng, Chao-Qiang

    2012-01-01

    We investigate the equation of state (EoS) of the scalar-torsion mode in Poincar\\'{e} gauge theory of gravity. 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 $w_r=1/3$ ($w_m=0$) 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.

  10. Worldsheet Instantons and Torsion Curves, Part A: Direct Computation

    CERN Document Server

    Braun, V; Ovrut, B A; Scheidegger, E; Braun, Volker; Kreuzer, Maximilian; Ovrut, Burt A.; Scheidegger, Emanuel

    2007-01-01

    As a first step towards studying vector bundle moduli in realistic heterotic compactifications, we identify all holomorphic rational curves in a Calabi-Yau threefold X with Z_3 x Z_3 Wilson lines. Computing the homology, we find that H_2(X,Z)=Z^3+Z_3+Z_3. The torsion curves complicate our analysis, and we develop techniques to distinguish the torsion part of curve classes and to deal with the non-toric threefold X. In this paper, we use direct A-model computations to find the instanton numbers in each integral homology class, including torsion. One interesting result is that there are homology classes that contain only a single instanton, ensuring that there cannot be any unwanted cancellation in the non-perturbative superpotential.

  11. Spin-Rotation Coupling in Gravitation with Torsion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the theory of gravitation with torsion developed by Hammond [Rep. Prog. Phys. 65 (2002)599], the interaction between the intrinsic spin of a particle and the mass source is calculated. It is shown that spin can interact with the gravitimagnetic field created by a rotational mass, where the spin-rotation coupling is also discussed.According to the recent torsion pendulum experiment with polarized electrons by Heckel et al. [Phys. Rev. Lett. 97(2006) 021603], we set a new limit on the value of the torsion coupling constant K as K ∈ [0.53, 0.95], which has improved many orders than the constraints from the early spin-spin experiment with K < 2 × 1014.

  12. Abnormalities of penile curvature: chordee and penile torsion.

    Science.gov (United States)

    Montag, Sylvia; Palmer, Lane S

    2011-07-28

    Congenital chordee and penile torsion are commonly observed in the presence of hypospadias, but can also be seen in boys with the meatus in its orthotopic position. Varying degrees of penile curvature are observed in 4-10% of males in the absence of hypospadias. Penile torsion can be observed at birth or in older boys who were circumcised at birth. Surgical management of congenital curvature without hypospadias can present a challenge to the pediatric urologist. The most widely used surgical techniques include penile degloving and dorsal plication. This paper will review the current theories for the etiology of penile curvature, discuss the spectrum of severity of congenital chordee and penile torsion, and present varying surgical techniques for the correction of penile curvature in the absence of hypospadias.

  13. Standing torsional waves in a fully saturated, porous, circular cylinder

    CERN Document Server

    Solorza, S; 10.1111/j.1365-246X.2004.02198.x

    2004-01-01

    For dynamic measurement of the elastic moduli of a porous material saturated with viscous fluid using the resonance-bar technique, one also observes attenuation. In this article we have carried out the solution of the boundary-value problem associated with standing torsional oscillations of a finite, poroelastic, circular cylinder cast in the framework of volume-averaged theory of poroelasticity. Analysing this solution by eigenvalue perturbation approach we are able to develop expressions for torsional resonance and temporal attenuation frequencies in which the dependence upon the material properties are transparent. It shows how the attenuation is controlled by the permeability and the fluid properties, and how the resonance frequency drops over its value for the dry solid-frame due to the drag effect of fluid mass. Based upon this work we have a firm basis to determine solid-frame shear modulus, permeability, and tortuosity factor from torsional oscillation experiments.

  14. Torsional impedance effect in Fe-rich amorphous wires

    Energy Technology Data Exchange (ETDEWEB)

    Prida, V.M. E-mail: vmpp@pinon.ccu.uniovi.es; Hernando, B.; Sanchez, M.L.; Li, Y.-F.; Tejedor, M.; Vazquez, M

    2003-03-01

    An amorphous ferromagnetic wire with a highly positive saturation magnetostriction constant, made of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1}, was simultaneously submitted to both, an AC current flowing through it and a torsional stress, in order to induce a helical magnetic anisotropy that modifies the magnetic domain structure and therefore the magnetic response of the sample. We study the torsion-impedance effect in an Fe-rich amorphous wire when it is submitted to different applied torsional stresses in both senses, up to 0.8{pi} rad/cm, as a function of the drive current frequency, in the range of 10 Hz-2 MHz. The experimental results are explained on the basis of the core-shell magnetic structure model combined with the skin effect.

  15. Abnormalities of Penile Curvature: Chordee and Penile Torsion

    Directory of Open Access Journals (Sweden)

    Sylvia Montag

    2011-01-01

    Full Text Available Congenital chordee and penile torsion are commonly observed in the presence of hypospadias, but can also be seen in boys with the meatus in its orthotopic position. Varying degrees of penile curvature are observed in 4–10% of males in the absence of hypospadias. Penile torsion can be observed at birth or in older boys who were circumcised at birth. Surgical management of congenital curvature without hypospadias can present a challenge to the pediatric urologist. The most widely used surgical techniques include penile degloving and dorsal plication. This paper will review the current theories for the etiology of penile curvature, discuss the spectrum of severity of congenital chordee and penile torsion, and present varying surgical techniques for the correction of penile curvature in the absence of hypospadias.

  16. Torsion-balance experiments and ultra-low-mass fields

    Science.gov (United States)

    Terrano, William

    2017-01-01

    Many of the solutions to outstanding problems in modern cosmology posit new, ultra-light fields. Unifying General Relativity and Quantum Mechanics appears to require new ultra-light fields at some level. Such fields are also invoked to drive inflation and dark energy. Ultra-light fields may also make up much or all of the dark matter density of the universe. Torsion pendulums, a technology that dates to the 18th century, remain one of the most sensitive experimental techniques to search for ultra-light, weakly interacting fields. I will explain how torsion balance experiments can search for beyond-the-standard-model fields using laboratory-based as well as galactic sources, and the important cosmological implications of these measurements. I will also describe a new experimental signature for which certain torsion balance geometries make very sensitive direct dark matter detectors over a broad range of interesting dark matter parameter space.

  17. Left-sided omental torsion with inguinal hernia

    Institute of Scientific and Technical Information of China (English)

    Yasumitsu Hirano; Kaeko Oyama; Hiroshi Nozawa; Takuo Hara; Koichi Nakada; Masahiro Hada; Takeshi Takagi; Makoto Hirano

    2006-01-01

    We report a case of surgically proved left-sided torsion of the greater omentum that caused secondary by untreated inguinal hernia. Case A 36-year-old man presented to our hospital with abdominal pain. He had been diagnosed with a left inguinal hernia, but he had not received any treatments. Contrast-enhanced computed tomography (CT) of the abdomen showed a large fat density mass below the Sigmoid colon and left inguinal hernia with incarcerated fat. Exploratory laparotomy revealed torsion of the greater omentum with small bloody ascites. The greater omentum was twisted into one and a half circles and entered into a left inguinal hernia. An omentectomy with a repair of left inguinal hernia was performed. A resected omentum was submitted for pathological examination, which showed hemorrhagic infarction. Omental torsion is a rare cause of acute abdominal pain but should be included in the differential diagnoses of acute abdomen, especially in patients with untreated inguinal hernia.

  18. The geometro-hydrodynamical representation of the torsion field

    Science.gov (United States)

    Trukhanova, Mariya, Iv.

    2017-09-01

    We construct the geometro-hydrodynamical formalism for a spinning particle based on the six-dimensional manifold of autoparallelism geometry which is represented as a vector bundle with a base formed by the manifold of the translational coordinates and a fiber specified at each point by the field of an orthogonal coordinate frame underlying the classical spin. We show that the geometry of oriented points leads to the existence of torsion field with the source - the classical spin. We expand the geometro-hydrodynamical representation of Pauli field developed by Takabayasi and Vigier. We show that the external torsion field has a force effect on the velocity and spin fields via the spin-vorticity, which is characteristic of the space structure with the inhomogene triad field. The possible experimental effects of torsion field are discussed.

  19. Mechanical Design of AM Fabricated Prismatic Rods under Torsion

    Directory of Open Access Journals (Sweden)

    Manzhirov Alexander V.

    2017-01-01

    Full Text Available We study the stress-strain state of viscoelastic prismatic rods fabricated or repaired by additive manufacturing technologies under torsion. An adequate description of the processes involved is given by methods of a new scientific field, mechanics of growing solids. Three main stages of the deformation process (before the beginning of growth, in the course of growth, and after the termination of growth are studied. Two versions of statement of two problems are given: (i given the torque, find the stresses, displacements, and torsion; (ii given the torsion, find the stresses, displacements, and torque. Solution methods using techniques of complex analysis are presented. The results can be used in mechanical and instrument engineering.

  20. Spin and torsion in the very early universe

    Energy Technology Data Exchange (ETDEWEB)

    Baeuerle, G.G.A.; Haneveld, C.J. (Amsterdam Univ. (Netherlands). Inst. voor Theoretische Fysica)

    1983-09-01

    In the very early universe with temperature T between 10/sup 24/ K and 10/sup 32/ K the gravitational effect of torsion is dominant if particles with spin are sufficiently polarized. The source of the torsion is the spin density and the latter is usually described by a classical theory of Weyssenhoff and Raabe. In this article the spinning particles are described quantum mechanically, i.e. with a Dirac field and the spin density is defined as the source of the torsion. The macroscopic average of the spin density is obtained by the relativistic Wigner function formalism. The expression of the spin density, as derived in this article, is different from the classical one, except when both are zero.

  1. Torsional instability in suspension bridges: The Tacoma Narrows Bridge case

    Science.gov (United States)

    Arioli, Gianni; Gazzola, Filippo

    2017-01-01

    All attempts of aeroelastic explanations for the torsional instability of suspension bridges have been somehow criticised and none of them is unanimously accepted by the scientific community. We suggest a new nonlinear model for a suspension bridge and we perform numerical experiments with the parameters corresponding to the collapsed Tacoma Narrows Bridge. We show that the thresholds of instability are in line with those observed the day of the collapse. Our analysis enables us to give a new explanation for the torsional instability, only based on the nonlinear behavior of the structure.

  2. A monolithically integrated torsional CMOS-MEMS relay

    Science.gov (United States)

    Riverola, M.; Sobreviela, G.; Torres, F.; Uranga, A.; Barniol, N.

    2016-11-01

    We report experimental demonstrations of a torsional microelectromechanical (MEM) relay fabricated using the CMOS-MEMS approach (or intra-CMOS) which exploits the full foundry inherent characteristics enabling drastic reduction of the fabrication costs and batch production. In particular, the relay is monolithically integrated in the back end of line of a commercial standard CMOS technology (AMS 0.35 μm) and released by means of a simple one-step mask-less wet etching. The fabricated torsional relay exhibits an extremely steep switching behaviour symmetrical about both contact sides with an on-state contact resistance in the k Ω -range throughout the on-off cycling test.

  3. Holography in 3D AdS gravity with torsion

    CERN Document Server

    Blagojević, Milutin; Miskovic, Olivera; Olea, Rodrigo

    2013-01-01

    Basic aspects of the AdS/CFT correspondence are studied in the framework of 3-dimensional gravity with torsion. After choosing a consistent holographic ansatz, we formulate an improved approach to the Noether--Ward identities for the boundary theory. The method is applied first to the topological Mielke--Baekler model, and then to the more interesting (parity-preserving) 3-dimensional gravity with propagating torsion. In both cases, we find the finite holographic energy-momentum and spin currents and obtain the associated (anomalous) Noether--Ward identities.

  4. Non-Kaehler string backgrounds and their five torsion classes

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, G.L. E-mail: gcardoso@physik.hu-berlin.de; Curio, G. E-mail: curio@physik.hu-berlin.de; Dall' Agata, G. E-mail: dallagat@physik.hu-berlin.de; Luest, D. E-mail: luest@physik.hu-berlin.de; Manousselis, P. E-mail: pman@central.ntua.gr; Zoupanos, G. E-mail: george.zoupanos@cern.ch

    2003-03-03

    We discuss the mathematical properties of six-dimensional non-Kaehler manifolds which occur in the context of N=1 supersymmetric heterotic and type IIA string compactifications with non-vanishing background H-field. The intrinsic torsion of the associated SU(3) structures falls into five different classes. For heterotic compactifications we present an explicit dictionary between the supersymmetry conditions and these five torsion classes. We show that the non-Ricci-flat Iwasawa manifold solves the supersymmetry conditions with non-zero H-field, so that it is a consistent heterotic supersymmetric groundstate.

  5. A Note on Torsion of Nonlocal Composite Nanobeams

    Directory of Open Access Journals (Sweden)

    Luciano Feo

    2016-01-01

    Full Text Available The ERINGEN elastic constitutive relation is used in this paper in order to assess small-scale effects in nanobeams. Structural behavior is studied for functionally graded materials in the cross-sectional plane and torsional loading conditions. The governing boundary value problem has been formulated in a mixed framework. Torsional rotations and equilibrated moments are evaluated by solving a first-order differential equation of elastic equilibrium with boundary conditions of kinematic-type. Benchmarks examples are briefly discussed, enlightening thus effectiveness of the proposed methodology.

  6. Torsion impedance of CoFeSiB amorphous wires

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, M.L. E-mail: grande@pinon.ccu.uniovi.es; Prida, V.M.; Hernando, B.; Tejedor, M.; Vazquez, M

    2002-08-01

    In this work we report some results concerning the torsion impedance of amorphous Co{sub 68.1}Fe{sub 4.4}Si{sub 12.5}B{sub 15} wires in the as-cast state, and after a stress annealing treatment. The influence of the drive current amplitude and frequency is also studied for these samples. A sensitivity to the applied torsion up to 17.6%/rad m is obtained for the annealed wire. The magnetoimpedance response of both types of samples gives evidence to the difference in their domain structure.

  7. Gravitational and torsion waves in linearised teleparallel gravity

    CERN Document Server

    Garcia de Andrade, L C

    2002-01-01

    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.

  8. Primary decomposition of torsion R[X]-modules

    Directory of Open Access Journals (Sweden)

    William A. Adkins

    1994-01-01

    Full Text Available This paper is concerned with studying hereditary properties of primary decompositions of torsion R[X]-modules M which are torsion free as R-modules. Specifically, if an R[X]-submodule of M is pure as an R-submodule, then the primary decomposition of M determines a primary decomposition of the submodule. This is a generalization of the classical fact from linear algebra that a diagonalizable linear transformation on a vector space restricts to a diagonalizable linear transformation of any invariant subspace. Additionally, primary decompositions are considered under direct sums and tensor product.

  9. RARE PRESENTATION OF A CASE OF TESTICULAR TORSION

    Directory of Open Access Journals (Sweden)

    Mohapatra

    2014-06-01

    Full Text Available A 12yrs male child presented in the emergency department of VSS Medical College Burla with complains of acute pain over left testis for 3days, associated with vomiting, there was no h/o fever, trauma or lower urinary tract symptoms. Ultrasonography of scrotum revealed features of testicular torsion with absent vascularity. He was managed with urgent scrotal exploration and found to have torsion of cord and gangrene of testis. Orchidectomy was done for testis with orchiopexy of the contralateral testis.

  10. HOMOLOGICAL PROPERTIES OF TORSION CLASSES UNDER CHANGE OF RINGS

    Institute of Scientific and Technical Information of China (English)

    YAOMUSHENG

    1994-01-01

    Let R be a ring with identity, x be a central element of R which is neither a unit nor a zero divisor. S=R/xR is the quotient ring of R and φ:R→R/xR is the natural map. R-Mod(resp.S-Mod) denotes the category of unital left R-modules(resp.S-modules).In this paper, relationships betwee torsion theories on R-Mod and torsion theories on S-Mod are investigated. Properties of the functor ExtRn(N,-) are given. Properties of the localization functor Qσ are also investigated.

  11. Torsion Testing of Diffusion Bonded LIGA Formed Nickel

    Energy Technology Data Exchange (ETDEWEB)

    Buchheit, T.E.; Christenson, T.R.; Schmale, D.T.

    1999-01-27

    A test technique has been devised which is suitable for the testing of the bond strength of batch diffusion bonded LIGA or DXRL defined structures. The method uses a torsion tester constructed with the aid of LIGA fabrication and distributed torsion specimens which also make use of the high aspect ratio nature of DXRL based processing. Measurements reveal achieved bond strengths of 130MPa between electroplated nickel with a bond temperature of 450 C at 7 ksi pressure which is a sufficiently low temperature to avoid mechanical strength degradation.

  12. Singularities and n-dimensional black holes in torsion theories

    CERN Document Server

    Cembranos, J A R; Torralba, F J Maldonado

    2016-01-01

    In this work we have studied the singular behaviour of gravitational theories with non symmetric connections. For this purpose we introduce a new criteria for the appearance of singularities based on the existence of black/white hole regions of arbitrary codimension defined inside a spacetime of arbitrary dimension. We discuss this prescription by increasing the complexity of the particular torsion theory under study. In this sense, we start with Teleparallel Gravity, then we analyse Einstein-Cartan theory, and finally dynamical torsion models.

  13. Contact Angle Goniometer

    Data.gov (United States)

    Federal Laboratory Consortium — Description:The FTA32 goniometer provides video-based contact angle and surface tension measurement. Contact angles are measured by fitting a mathematical expression...

  14. Aerodynamic stability of long span suspension bridges with low torsional natural frequencies

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Johansson, Jens; Brandt, Anders;

    2016-01-01

    Classical flutter of suspended bridge decks can be avoided if the torsional frequencies are lower than the vertical. Wind tunnel tests of single boxes and twin box section models with torsional natural frequencies above and below the vertical frequency has been conducted. Flutter was avoided in a....... In order to design aerodynamically stable suspension bridges with low torsional natural frequencies it is suggested to increase the mass moment of inertia and provide adequate torsional stiffness by the main cables spacing....

  15. Aerodynamic stability of long span suspension bridges with low torsional natural frequencies

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Johansson, Jens; Brandt, Anders

    2016-01-01

    Classical flutter of suspended bridge decks can be avoided if the torsional frequencies are lower than the vertical. Wind tunnel tests of single boxes and twin box section models with torsional natural frequencies above and below the vertical frequency has been conducted. Flutter was avoided in all....... In order to design aerodynamically stable suspension bridges with low torsional natural frequencies it is suggested to increase the mass moment of inertia and provide adequate torsional stiffness by the main cables spacing....

  16. Ultrasonographic diagnosis of torsion of testicular appendages; Diagnostico por ecografia de la torsion de los apendices testiculares

    Energy Technology Data Exchange (ETDEWEB)

    Esparza, J.; Gonzalez, A.; Cordero, J. L. [Hospital Virgen del Camino. Pamplona (Spain)

    2000-07-01

    To determine the efficacy of ultrasound in boys presenting torsion of a testicular appendage. A series of 30 boys with acute scrotal pain due to torsion of a testicular appendage was studied. Nine patients underwent surgery. The clinical findings and course in the remaining 21 suggested the presence of this abnormality. All of them underwent conventional and color Doppler ultrasound using a 7.5 MHz transducer. In 15 boys, ultrasound images depicted the affected appendage as a mass between the epididymal head and the testicle. In 13 cases, only signs of a inflammatory reaction, with enlargement of the epididymal head and tunicas presenting hyperflow and hydrocele, mimicking acute epididymities. In two cases, the images were normal. There is no definitive, distinguishing ultrasound image corresponding to testicular appendage torsion. Therefore, this diagnostic technique should be accompanied by clinical assessment. (Author) 14 refs.

  17. Torsion, a multivalued gauge degree of freedom in Einstein's gravity

    Energy Technology Data Exchange (ETDEWEB)

    Kleinert, H, E-mail: h.k@fu-berlin.de [Institut fuer Theoretische Physik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin (Germany); ICRANet, Piazzale della Republica 10, 1-65122, Pescara (Italy)

    2011-07-08

    We show that there is an entire gauge symmetry of a novel kind which interpolates between an infinity of formulations of the laws of gravity, ranging from Einsteins pure curvature formulation to a pure torsion formulation in a teleparallel geometry. As a consequence, torsion and curvature are not independent and that torsion is an alternative description of curvature in gravity.

  18. Vibration mode of torsion balance and its response to external shock

    Institute of Scientific and Technical Information of China (English)

    汤洁; 罗俊; 范淑华

    1997-01-01

    Intrinsic vibration modes of typical torsion balances and their response to the external shock are discussed in detail. The study is important and instructive for improving measurement precision of gravitational experiments employing torsion balances, and gives a reasonable interpretation on detecting earthquake by high precision torsion balance.

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

    Science.gov (United States)

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

    2015-05-01

    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.

  20. A 55-Year-Old Man with Right Testicular Pain: Too Old for Torsion?

    Science.gov (United States)

    Tang, Yu Ho; Yeung, Victor Hip Wo; Chu, Peggy Sau Kwan; Man, Chi Wai

    2017-02-01

    Testicular torsion is predominantly a disease of adolescence, but age itself should not be an exclusion criterion for the diagnosis. A lack of suspicion for testicular torsion in older patients may result in a missed or delayed diagnosis which jeopardizes the chance of testicular salvage. In this article, we report a case of testicular torsion in a 55-year-old Chinese man.

  1. Successive Torsion of the Right Middle and Left Cranial Lung Lobes in a Dog

    OpenAIRE

    Breton, Luc; DiFruscia, Rocky; Olivieri, Michel

    1986-01-01

    This case report describes the torsion of two lung lobes in a dog. The animal was first presented for a torsion of the right middle lung lobe. Following the surgical resection of that lobe, the dog suffered another torsion of the left cranial lung lobe (cranial and caudal segments).

  2. Dirac theory in space-time without torsion

    CERN Document Server

    Hannibal, L

    1994-01-01

    It is proven that the usual quadratic general-covariant Lagrangian for the Dirac field leads to a symmetric, divergence-free energy-momentum tensor in the standard Riemannian framework of space-time without torsion, provided the tetrad field components are the only quantities related to gravitation that are varied independently.

  3. Ocular torsion before and after 1 hour centrifugation

    NARCIS (Netherlands)

    Groen, E.; Graaf, B. de; Bles, W.; Bos, J.E.

    1996-01-01

    To assess a possible otolith contribution to effects observed following prolonged expo-sure to hyper gravity, we used video-oculography to measure ocular torsion during static and dynamic conditions of lateral body tilt (roll) before and after one hour of centrifugation with a Gx-load of 3G. Static

  4. Numerical Simulation of Gleeble Torsion Testing of HSLA-65 Steel

    Science.gov (United States)

    2008-04-01

    LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 36 19b. TELEPHONE NUMBER (include area code) 301 -227-5033 Standard Form 298 (Rev. 8-98...3800 Torsion machine on AISI 304L and HSLA-65 steels to simulate the friction stir welding of these materials. A photograph of the experimental setup

  5. Torsion stiffness of a protein pair determined by magnetic particles

    NARCIS (Netherlands)

    Janssen, X.J.A.; Van Noorloos, J.M.; Jacob, A.; Van IJzendoorn, L.J.; De Jong, A.M.; Prins, M.W.J.

    2012-01-01

    We demonstrate the ability to measure torsion stiffness of a proteincomplex by applying a controlled torque on a magnetic particle. Asa model system we use protein G bound to an IgG antibody. The protein pair is held between a magnetic particle and a polystyrene substrate. The angular orientation of

  6. Ectopic ovary with torsion: uncommon diagnosis made by ultrasound

    Science.gov (United States)

    Castro, Adham do Amaral e; Morandini, Fernando; Calixto, Caroline Paludo; Barros, Wagner Haese; Nakatani, Edson Tetsuya; Castro, Allan do Amaral e

    2017-01-01

    Ultrasound is an important diagnostic tool in inguinal hernia and in the evaluation of the contents of the hernia sac. This report presents a case in which ultrasound revealed a herniated ectopic ovary, complicated by torsion of its vascular pedicle, in the right labia majora. We also present a brief discussion of ovarian hernia, its potential complications, and the treatments available. PMID:28298734

  7. Torsion and CO-stretching vibration interactions in methanol

    Science.gov (United States)

    Duan, Yun-Bo; Yuan, Shuping; Wang, Rubin; Mukhopadhyay, I.

    2006-11-01

    A model Hamiltonian is constructed to investigate the vibration-torsion-rotational interaction in methanol. The model Hamiltonian is based on the formulation of reduction of Hamiltonian, in which the CO-stretching mode ν8, the large-amplitude torsion mode ν12 and the three degrees of freedom that correspond to the overall rotation of the molecule, are considered simultaneously. This Hamiltonian is used to carry out an analysis of already published data for CH 3OH with vco ⩽ 1 (the CO-stretching vibrational quantum number), vt ⩽ 4 (the torsional quantum number), and J ⩽ 5 (the overall rotational quantum number). The relative locations of the CO-stretch vibrational ground state and the fundamental state are well reproduced for torsional states with vt ⩽ 4 and J ⩽ 5. An effective potential energy surface that describes ν8 and ν12 modes is obtained from this analysis. The present analyses show that a variety of resonance interactions can affect states for energies larger than 1100 cm -1.

  8. The human ocular torsion position response during yaw angular acceleration.

    Science.gov (United States)

    Smith, S T; Curthoys, I S; Moore, S T

    1995-07-01

    Recent results by Wearne [(1993) Ph.D. thesis] using the scleral search-coil method of measuring eye position indicate that changes in ocular torsion position (OTP) occur during yaw angular acceleration about an earth vertical axis. The present set of experiments, using an image processing method of eye movement measurement free from the possible confound of search coil slippage, demonstrates the generality and repeatability of this phenomenon and examines its possible causes. The change in torsion position is not a linear vestibulo-ocular reflex (LVOR) response to interaural linear acceleration stimulation of the otoliths, but rather the effect is dependent on the characteristics of the angular acceleration stimulus, commencing at the onset and decaying at the offset of the angular acceleration. In the experiments reported here, the magnitude of the angular acceleration stimulus was varied and the torsion position response showed corresponding variations. We consider that the change in torsion position observed during angular acceleration is most likely to be due to activity of the semicircular canals.

  9. Torsional Newton-Cartan geometry and the Schrodinger algebra

    NARCIS (Netherlands)

    Bergshoeff, Eric A.; Hartong, Jelle; Rosseel, Jan

    2015-01-01

    We show that by gauging the Schrodinger algebra with critical exponent z and imposing suitable curvature constraints, that make diffeomorphisms equivalent to time and space translations, one obtains a geometric structure known as (twistless) torsional Newton-Cartan geometry (TTNC). This is a version

  10. Torsion of an Epiploic Appendix Pretending as Acute Appendicitis

    Directory of Open Access Journals (Sweden)

    Kamran Ahmad Malik

    2010-07-01

    Full Text Available 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

  11. In vitro transcription of a torsionally constrained template

    DEFF Research Database (Denmark)

    Bentin, Thomas; Nielsen, Peter E

    2002-01-01

    of torsionally constrained DNA by free RNAP. We asked whether or not a newly synthesized RNA chain would limit transcription elongation. For this purpose we developed a method to immobilize covalently closed circular DNA to streptavidin-coated beads via a peptide nucleic acid (PNA)-biotin conjugate in principle...

  12. Primary omental torsion in a 12-year-old boy

    Institute of Scientific and Technical Information of China (English)

    曹文刚; 张金哲

    2001-01-01

    @@Primany omental torsion (POT), known since 1899, is a disease that usually occurs in the fourth and fifth decades of life. Men are affected twice as frequently as women, with the majority being overweight.1 It is a rare acute abdomen among children, which should call for the special awareness of pediatric surgeons.

  13. Determination of ocular torsion by means of automatic pattern recognition

    NARCIS (Netherlands)

    Groen, E.L.; Bos, J.E.; Nacken, P.F.M.; Graaf, B. de

    1996-01-01

    A new, automatic method for determination of human ocular torsion (OT) was devel-oped based on the tracking of iris patterns in digitized video images. Instead of quanti-fying OT by means of cross-correlation of circular iris samples, a procedure commonly applied, this new method automatically selec

  14. Direct excitation of resonant torsional Alfven waves by footpoint motions

    NARCIS (Netherlands)

    Ruderman, M. S.; Berghmans, D.; Goossens, M.; Poedts, S.

    1997-01-01

    The present paper studies the heating of coronal loops by linear resonant Alfven waves that are excited by the motions of the photospheric footpoints of the magnetic field lines. The analysis is restricted to torsionally polarised footpoint motions in an axially symmetric system so that only

  15. Contravariantly finite subcategories in a tilting torsion class

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The contravariant finiteness of the subcategory consisting of modules with T-dimension not more than 1 in the torsion class induced by a tilting module T is proved under the condition that the projective dimension of the injective hull of the tilting module is not more than one.

  16. Anomalous Majorana Neutrino Masses from Torsionful Quantum Gravity

    CERN Document Server

    Mavromatos, Nick E

    2012-01-01

    The effect of quantum torsion in theories of quantum gravity is usually described by an axion-like field which couples to matter and to gravitation and radiation gauge fields. In perturbation theory, the couplings of this torsion-descent axion field are of derivative type and so preserve a shift symmetry. This shift symmetry may be broken, if the torsion-descent axion field mixes with other axions, which could be related to moduli fields in string-inspired effective theories. In particular, the shift symmetry may break explicitly via non-perturbative effects, when these axions couple to fermions via chirality changing Yukawa couplings with appropriately suppressed coefficients. We show, how in such theories an effective right-handed Majorana neutrino mass can be generated at two loops by gravitational interactions that involve global anomalies related to quantum torsion. We estimate the magnitude of the gravitationally induced Majorana mass and find that it is highly model dependent, ranging from multi-TeV to...

  17. Ponzano-Regge Model on Manifold with Torsion

    CERN Document Server

    Vargas, T

    2013-01-01

    The connection between angular momentum in quantum mechanics and geometric objects is extended to manifold with torsion. First, we notice the relation between the $6j$ symbol and Regge's discrete version of the action functional of Euclidean three dimensional gravity with torsion, then consider the Ponzano and Regge asymptotic formula for the Wigner $6j$ symbol on this simplicial manifold with torsion. In this approach, a three dimensional manifold $M$ is decomposed into a collection of tetrahedra, and it is assumed that each tetrahedron is filled in with flat space and the torsion of $M$ is concentrated on the edges of the tetrahedron, the length of the edge is chosen to be proportional to the length of the angular momentum vector in semiclassical limit. The Einstein-Hilbert action is then a function of the angular momentum and the Burgers vector of dislocation, and it is given by summing the Regge action over all tetrahedra in $M$. We also discuss the asymptotic approximation of the partition function and t...

  18. Penile torsion correction by diagonal corporal plication sutures

    Directory of Open Access Journals (Sweden)

    Brent W. Snow

    2009-02-01

    Full Text Available Penile torsion is commonly encountered. It can be caused by skin and dartos adherence or Buck’s fascia attachments. The authors suggest a new surgical approach to solve both problems. If Buck’s fascia involvement is demonstrated by artificial erection then a new diagonal corporal plication suture is described to effectively solve this problem.

  19. The Torsion-Extension Coupling in Pretwisted Elastic Beams

    DEFF Research Database (Denmark)

    Krenk, Steen

    1983-01-01

    An explicit asymptotic formula is derived for the untwist of a pretwisted elastic beam subjected to homogeneous extension or equivalently for the longitudinal contraction produced by a torsional moment. It is based on an asymptotic expansion of the three dimensional equations of linear elasticity...

  20. Spectral Action for Torsion with and without Boundaries

    DEFF Research Database (Denmark)

    Iochum, B.; Levy, Cyril Olivier; Vassilevich, D.

    2012-01-01

    We derive a commutative spectral triple and study the spectral action for a rather general geometric setting which includes the (skew-symmetric) torsion and the chiral bag conditions on the boundary. The spectral action splits into bulk and boundary parts. In the bulk, we clarify certain issues...

  1. Oxidative and antioxidative defense system in testicular torsion/detorsion

    Directory of Open Access Journals (Sweden)

    F A Elshaari

    2011-01-01

    Full Text Available Aim: The present study was aimed to assess the early effects of ischemia/reperfusion injury on the oxidants and anti-oxidant defense status in rat testicular tissue by measuring MDA, glucose-6-phosphte dehydrogenase activity and reduced glutathione levels in a designated time frame sequel to reperfusion. Animals were divided randomly into six groups (12 animals per group in the following order: Group I: Sham-operated control group (Cso without the application of the torsion. Group 2: Torsion-induced ischemia group (T30 m: Ischemia was induced through the torsion of spermatic cord for a period of 30 min. Group 3: One hour reperfusion group after detorsion (T30 mR1 h. Group 4: Twenty-four hour reperfusion group after detorsion (T30 mR24 h. Group 5: Forty-eight hours reperfusion group after detorsion (T30mR48h. Group 6: One week reperfusion group after detorsion (T30mR1wk. Results and Discussion: The oxidant-antioxidant system of the testicular tissue is altered during torsion as well as detorsion which results in the altered activities involved in the key enzyme of hexose monophosphate shunt pathway, glucose 6 phosphate dehydrogenase activity along with a reduction of glutathione (G.SH content. The increase in G6PDH activity during torsion and followed by an increase in detorsion indicates the tissue′s response to counter the oxidant stress caused by reduced blood supply. Continued exposure to such oxidant stressed physiological state of a tissue may lead to decreased capacity of the tissue to perform its physiological function such as testicular steroidogenesis and spermiogenesis shown in the present study.

  2. Development of a Meso-Scale SMA-Based Torsion Actuator for Image-Guided Procedures.

    Science.gov (United States)

    Sheng, Jun; Gandhi, Dheeraj; Gullapalli, Rao; Simard, J Marc; Desai, Jaydev P

    2017-02-01

    This paper presents the design, modeling, and control of a meso-scale torsion actuator based on shape memory alloy (SMA) for image-guided surgical procedures. Developing a miniature torsion actuator is challenging, but it opens the possibility of significantly enhancing the robot agility and maneuverability. The proposed torsion actuator is bi-directionally actuated by a pair of antagonistic SMA torsion springs through alternate Joule heating and natural cooling. The torsion actuator is integrated into a surgical robot prototype to demonstrate its working performance in the humid environment under C-Arm CT image guidance.

  3. Microstructural Evolution and Structure-Hardness Relationship in an Al-4wt.%Mg Alloy Processed by High-Pressure Torsion

    Science.gov (United States)

    Yang, Xiaohui; Yi, Jianhong; Ni, Song; Du, Yong; Song, Min

    2016-05-01

    Coarse-grained Al-4wt.%Mg alloy with high stacking fault energy was deformed by high-pressure torsion (HPT) at room temperature. The HPT-induced grain refinement process of the alloy can be clarified as follows: (1) the randomly distributed dislocations firstly interact and rearrange to form dislocation cells; (2) with increasing the strain, these cell boundaries transform to small-angle grain boundaries that act as the dislocation sources, and therefore Shockley partial dislocations on the glide plane (111) can be easily emitted to accommodate plastic deformation; (3) along with the partial dislocations emission from low angle grain boundaries, the low angle grain boundaries gradually transform into the high angle grain boundaries. The relationship between the microstructural evolution and hardness was also investigated. It has been shown that the relationship between grain size and hardness deviates from the Hall-Petch linear relationship.

  4. Torsional vibration measurements on rotating shaft system using laser doppler vibrometer

    Science.gov (United States)

    Xiang, Ling; Yang, Shixi; Gan, Chunbiao

    2012-11-01

    In this work, a laser torsional vibrameter was used to measure the torsion vibration of a rotating shaft system under electrical network impact. Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) are non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. Furthermore, a highly complex shafting system is analyzed by a modified Riccati torsional transfer matrix. The system is modeled as a chain consisting of an elastic spring with concentrated mass points, and the multi-segments lumped mass model is established for this shafting system. By the modified Riccati torsional transfer matrix method, an accumulated calculation is effectively eliminated to obtain the natural frequencies. The electrical network impacts can activize the torsional vibration of shaft system, and the activized torsion vibration frequencies contained the natural frequencies of shaft system. The torsional vibrations of the shaft system were measured under electrical network impacts in laser Doppler torsional vibrometer. By comparisons, the natural frequencies by measurement were consistent with the values by calculation. The results verify the instrument is robust, user friendly and can be calibrated in situ. The laser torsional vibrometer represents a significant step forward in rotating machinery diagnostics.

  5. Transitional Failure of Carbon Nanotube Systems under a Combination of Tension and Torsion

    Directory of Open Access Journals (Sweden)

    Byeong-Woo Jeong

    2012-01-01

    Full Text Available Transitional failure envelopes of single- and double-walled carbon nanotubes under combined tension-torsion are predicted using classical molecular dynamics simulations. The observations reveal that while the tensile failure load decreases with combined torsion, the torsional buckling moment increases with combined tension. As a result, the failure envelopes under combined tension-torsion are definitely different from those under pure tension or torsion. In such combined loading, there is a multitude of failure modes (tensile failure and torsional buckling, and the failure consequently exhibits the feature of transitional failure envelopes. In addition, the safe region of double-walled carbon nanotubes is significantly larger than that of single-walled carbon nanotubes due to the differences in the onset of torsional buckling.

  6. Torsion Dependence of Domain Transition and MI Effect of Melt-Extracted Co68.15Fe4.35Si12.25B13.25Nb1Cu1 Microwires

    Directory of Open Access Journals (Sweden)

    Dawei Xing

    2015-01-01

    Full Text Available We present the torsional stress induced magnetoimpedance (MI effect and surface domain structure evolution of magnetostrictive melt-extracted Co68.15Fe4.35Si12.25B13.25Nb1Cu1 microwires. Experimental results indicate that the surface domain structures observed by magnetic force microscope (MFM transform from the weak circumferential domain of as-cast state to the helical domain under large torsional strain of 81.6 (2π rad/m. Domain wall movement distorts at torsional strain ξ=20.4 (2π rad/m and forms a helical anisotropy with an angle of around 30° versus axial direction of wire. At 15 MHz, the maximum of GMI ratio ΔZ/Z(% increases to 194.4% at ξ=20.4 (2π rad/m from 116.3% of the as-cast state and then decreases to 134.9% at ξ=102.0 (2π rad/m. The torsion magnetoimpedance (TMI ratio ΔZ/Zξ(% is up to 290%. Based on this large torsional strain and high MI ratio, the microwire can be as an referred candidate for high-performance TMI sensor application.

  7. An energy harvester using piezoelectric cantilever beams undergoing coupled bending-torsion vibrations

    Science.gov (United States)

    Abdelkefi, A.; Najar, F.; Nayfeh, A. H.; Ben Ayed, S.

    2011-11-01

    Recently, piezoelectric cantilevered beams have received considerable attention for vibration-to-electric energy conversion. Generally, researchers have investigated a classical piezoelectric cantilever beam with or without a tip mass. In this paper, we propose the use of a unimorph cantilever beam undergoing bending-torsion vibrations as a new piezoelectric energy harvester. The proposed design consists of a single piezoelectric layer and a couple of asymmetric tip masses; the latter convert part of the base excitation force into a torsion moment. This structure can be tuned to be a broader band energy harvester by adjusting the first two global natural frequencies to be relatively close to each other. We develop a distributed-parameter model of the harvester by using the Euler-beam theory and Hamilton's principle, thereby obtaining the governing equations of motion and associated boundary conditions. Then, we calculate the exact eigenvalues and associated mode shapes and validate them with a finite element (FE) model. We use these mode shapes in a Galerkin procedure to develop a reduced-order model of the harvester, which we use in turn to obtain closed-form expressions for the displacement, twisting angle, voltage output, and harvested electrical power. These expressions are used to conduct a parametric study for the dynamics of the system to determine the appropriate set of geometric properties that maximizes the harvested electrical power. The results show that, as the asymmetry is increased, the harvester's performance improves. We found a 30% increase in the harvested power with this design compared to the case of beams undergoing bending only. We also show that the locations of the two masses can be chosen to bring the lowest two global natural frequencies closer to each other, thereby allowing the harvesting of electrical power from multi-frequency excitations.

  8. Effectiveness of damped braces to mitigate seismic torsional response of unsymmetric-plan buildings

    Science.gov (United States)

    Mazza, Fabio; Pedace, Emilia; Favero, Francesco Del

    2017-02-01

    The seismic retrofitting of unsymmetric-plan reinforced concrete (r.c.) framed buildings can be carried out by the incorporation of damped braces (DBs). Yet most of the proposals to mitigate the seismic response of asymmetric framed buildings by DBs rest on the hypothesis of elastic (linear) structural response. The aim of the present work is to evaluate the effectiveness and reliability of a Displacement-Based Design procedure of hysteretic damped braces (HYDBs) based on the nonlinear behavior of the frame members, which adopts the extended N2 method considered by Eurocode 8 to evaluate the higher mode torsional effects. The Town Hall of Spilinga (Italy), a framed structure with an L-shaped plan built at the beginning of the 1960s, is supposed to be retrofitted with HYDBs to attain performance levels imposed by the Italian seismic code (NTC08) in a high-risk zone. Ten structural solutions are compared by considering two in-plan distributions of the HYDBs, to eliminate (elastic) torsional effects, and different design values of the frame ductility combined with a constant design value of the damper ductility. A computer code for the nonlinear dynamic analysis of r.c. spatial framed structures is adopted to evaluate the critical incident angle of bidirectional earthquakes. Beams and columns are simulated with a lumped plasticity model, including flat surface modeling of the axial load-biaxial bending moment elastic domain at the end sections, while a bilinear law is used to idealize the behavior of the HYDBs. Damage index domains are adopted to estimate the directions of least seismic capacity, considering artificial earthquakes whose response spectra match those adopted by NTC08 at serviceability and ultimate limit states.

  9. Reliability of the assessment of lower limb torsion using computed tomography: analysis of five different techniques

    Energy Technology Data Exchange (ETDEWEB)

    Liodakis, Emmanouil; Doxastaki, Iosifina; Chu, Kongfai; Krettek, Christian; Gaulke, Ralph; Citak, Musa [Hannover Medical School, Trauma Department, Hannover (Germany); Kenawey, Mohamed [Sohag University Hospital, Orthopaedic Surgery Department, Sohag (Egypt)

    2012-03-15

    Various methods have been described to define the femoral neck and distal tibial axes based on a single CT image. The most popular are the Hernandez and Weiner methods for defining the femoral neck axis and the Jend, Ulm, and bimalleolar methods for defining the distal tibial axis. The purpose of this study was to calculate the intra- and interobserver reliability of the above methods and to determine intermethod differences. Three physicians separately measured the rotational profile of 44 patients using CT examinations on two different occasions. The average age of patients was 36.3 {+-} 14.4 years, and there were 25 male and 19 female patients. After completing the first two sessions of measurements, one observer chose certain cuts at the levels of the femoral neck, femoral condylar area, tibial plateau, and distal tibia. The three physicians then repeated all measurements using these CT cuts. The greatest interclass correlation coefficients were achieved with the Hernandez (0.99 intra- and 0.93 interobserver correlations) and bimalleolar methods (0.99 intra- and 0.92 interobserver correlations) for measuring the femoral neck and distal tibia axes, respectively. A statistically significant decrease in the interobserver median absolute differences could be achieved through the use of predefined CT scans only for measurements of the femoral condylar axis and the distal tibial axis using the Ulm method. The bimalleolar axis method underestimated the tibial torsion angle by an average of 4.8 and 13 compared to the Ulm and Jend techniques, respectively. The methods with the greatest inter- and intraobserver reliabilities were the Hernandez and bimalleolar methods for measuring femoral anteversion and tibial torsion, respectively. The high intermethod differences make it difficult to compare measurements made with different methods. (orig.)

  10. Reading Angles in Maps

    Science.gov (United States)

    Izard, Véronique; O'Donnell, Evan; Spelke, Elizabeth S.

    2014-01-01

    Preschool children can navigate by simple geometric maps of the environment, but the nature of the geometric relations they use in map reading remains unclear. Here, children were tested specifically on their sensitivity to angle. Forty-eight children (age 47:15-53:30 months) were presented with fragments of geometric maps, in which angle sections…

  11. Segmental Bridges under Combined Torsion, Bending and Shear

    Institute of Scientific and Technical Information of China (English)

    黄真; 刘西拉

    2003-01-01

    Segmental bridges with unbonded prestressed tendons have some advantages, such as the weather independence and the corrosion protection of prestressing tendons. This paper analyzed the behavior of a prestressed segmental bridge with unbonded tendons under combined loading of torsion, bending and shear. According to the experiment research, a modified skew bending model was developed to calculate the bearing capacity of segmental bridges subjected to combined bending, shear and torsion. The finite element method was used to investigate the deflection behaviors of such structure, also to check the theoretical model. The theoretical and FEM research resuits were compared favorably with the test results from Technical University of Braunschweig, Germany. Finally, suggestion for the design and construction of segmental bridges with external prestressing was made.

  12. Torsional Newton-Cartan Geometry from the Noether Procedure

    CERN Document Server

    Festuccia, Guido; Hartong, Jelle; Obers, Niels A

    2016-01-01

    We apply the Noether procedure for gauging space-time symmetries to theories with Galilean symmetries, analyzing both massless and massive (Bargmann) realizations. It is shown that at the linearized level the Noether procedure gives rise to (linearized) torsional Newton-Cartan geometry. In the case of Bargmann theories the Newton-Cartan form $M_\\mu$ couples to the conserved mass current. We show that even in the case of theories with massless Galilean symmetries it is necessary to introduce the form $M_\\mu$ and that it couples to a topological current. Further, we show that the Noether procedure naturally gives rise to a distinguished affine (Christoffel type) connection that is linear in $M_\\mu$ and torsionful. As an application of these techniques we study the coupling of Galilean electrodynamics to TNC geometry at the linearized level.

  13. Torsional Newton-Cartan geometry from the Noether procedure

    Science.gov (United States)

    Festuccia, Guido; Hansen, Dennis; Hartong, Jelle; Obers, Niels A.

    2016-11-01

    We apply the Noether procedure for gauging space-time symmetries to theories with Galilean symmetries, analyzing both massless and massive (Bargmann) realizations. It is shown that at the linearized level the Noether procedure gives rise to (linearized) torsional Newton-Cartan geometry. In the case of Bargmann theories the Newton-Cartan form Mμ couples to the conserved mass current. We show that even in the case of theories with massless Galilean symmetries it is necessary to introduce the form Mμ and that it couples to a topological current. Further, we show that the Noether procedure naturally gives rise to a distinguished affine (Christoffel type) connection that is linear in Mμ and torsionful. As an application of these techniques we study the coupling of Galilean electrodynamics to TNC geometry at the linearized level.

  14. Analysis of torsional vibration in an electromechanical transmission system

    Directory of Open Access Journals (Sweden)

    Kai Chen

    2016-06-01

    Full Text Available Aiming at the torsional vibration in the electromechanical transmission system, this article introduces the active vibration method and analyzes the vibration characteristics on the condition of the external excitation, and then, the condition of the permanent magnetic synchronous motor parameter is obtained. In the braking energy recovery working condition, the permanent magnetic synchronous motor is operated in generator mode and is subjected to power control, this cause it to produce negative effect of damping. Negative effect of damping leads to the increasing torsional vibration. Then, the improved power control strategy is introduced to reduce the vibration. Computer simulations are used to demonstrate the active vibration method and the effectiveness of the proposed control strategy, which provides reference for the design of electromechanical systems in the hybrid electrical vehicles.

  15. TORSIONAL DEFORMATION AND FATIGUE BEHAVIOUR OF 6061 ALUMINIUM ALLOY

    Directory of Open Access Journals (Sweden)

    marini marno

    2012-02-01

    Full Text Available Torsional deformation and fatigue behaviour of both solid and thin-walled tubular specimens were made from as-received and heat treated 6061 aluminium alloy were studied. 6061 aluminium alloy have been widely used as a candidate material in automobile, aerospace, aircraft and structural application because of their superior mechanical properties such as high strength to weight ratio, good ductility and others. The differences in cyclic deformation and fatigue behaviours between round and solid specimens where a stress gradient exist, and thin-walled tubular specimens where a uniform stress state is commonly assumed, are also discussed. Von Mises and Tresca criteria has been used to predict the monotonic and cyclic deformation curve and compared to the torsional data obtained from the experiment. The S-N curve was used to present and evaluate the fatigue life of the specimens. Through fractographic analysis, failure criteria of fracture surfaces were observed and discussed. 

  16. Drinfeld modules with maximal Galois action on their torsion points

    CERN Document Server

    Zywina, David

    2011-01-01

    To each Drinfeld module over a finitely generated field with generic characteristic, one can associate a Galois representation arising from the Galois action on its torsion points. Recent work of Pink and R\\"utsche has described the image of this representation up to commensurability. Their theorem is qualitative, and the objective of this paper is to complement this theory with a worked out example. In particular, we give examples of Drinfeld modules of rank 2 for which the Galois action on their torsion points is as large as possible. We will follow the approach that Serre used to give explicit examples of his openness theorem for elliptic curves. Using our specific examples, we will numerically test analogues of some well-known elliptic curve conjectures.

  17. Subsynchronous torsional interactions with static VAR compensators; Influence of HVDC

    Energy Technology Data Exchange (ETDEWEB)

    Rostamkolai, N.; Piwko, R.J.; Larsen, E.V. (General Electric Co., Schenectady, NY (USA)); Fisher, D.A. (New England Power Service Co., Westborough, MA (USA)); Mobarak, M.A. (New Brunswick Electric Power Commission, Fredericton, NB (Canada)); Poitras, A.E. (Maine Electric Power Co., Augusta, ME (US))

    1991-02-01

    Planning for installation of a static var compensator (SVC) in Chester, Maine, was initiated in 1987. The pre-specification subsynchronous torsional interaction (SSTI) studies showed the SVC might have a negative influence on stability of torsional modes of vibration of the nearby turbine-generators. In a previous paper, the parameters influencing the level of SSTI were identified with the use of a simple system. This paper extends the work to power systems containing an HVDC transmission system. The combined effect of SVC and HVDC on turbine-generator SSTI is investigated with the use of a hypothetical system. Simulation plots for the large machines of New Brunswick and Maine are included to quantify the level of interaction with the Chester SVC. Filtering as a mitigation measure is proposed to eliminate the small level of SSTI attributed to the Chester SVC.

  18. Torsion of the fallopian the mimicking appendicitis in a pregnant woman; Torsion de la trompa de Falopio en una mujer gestante simulando apendicitis

    Energy Technology Data Exchange (ETDEWEB)

    Tapia-Vine, M.; Pedrosa, I.; Escribano, N. [Hospital Clinico San Carlos (Spain)

    2000-07-01

    Isolated torsion of the fallopian tube is an uncommon entity. Given the difficulties involved in the preoperative diagnosis, the ultrasound findings characteristic of this anomaly are not widely known. We present a case of tubal torsion associated with a cyst, describing the ultrasound images in our case and those reported in the literature. (Author) 18 refs.

  19. Testicular torsion and weather conditions: analysis of 21,289 cases in Brazil

    Directory of Open Access Journals (Sweden)

    Fernando Korkes

    2012-04-01

    Full Text Available PURPOSE: The hypothesis of association between testicular torsion and hyperactive cremasteric reflex, worsened by cold weather, has not been proved. Thirteen studies in the literature evaluated this issue, with inconclusive results. The aim of the present study was to evaluate the seasonality of testicular torsion in a large subset of patients surgically treated in Brazil, and additionally to estimate the incidence of testicular torsion. MATERIALS AND METHODS: Brazilian Public Health System Database was assessed from 1992-2010 to evaluate hospital admissions associated with treatment of testicular torsion. Average monthly temperature between 1992-2010 was calculated for each region. RESULTS: We identified 21,289 hospital admissions for treatment of testicular torsion. There was a higher number of testicular torsions during colder months (p = 0.002. To estimate the incidence of testicular torsion, we have related our findings to data from the last Brazilian census (2010. In 2010, testicular torsion occurred in 1.4:100,000 men in Brazil. CONCLUSIONS:Testicular torsion occurred at an annual incidence of approximately 1.4:100,000 men in Brazil in 2010. Seasonal variations do occur, with a significant increase of events during winter. Our findings support the theory of etiological role of cold weather to the occurrence of testicular torsion. Strategies to prevent these events can be based on these findings.

  20. [Uterine torsion in cattle - frequency, clinical symptoms and theories about the pathogenesis].

    Science.gov (United States)

    Erteld, E; Wehrend, A; Goericke-Pesch, S

    2012-01-01

    Aim of the present study was to summarize the available literature about the incidence, frequency, clinical symptoms and ideas as to the pathogenesis of uterine torsion in the cow. Analysis of the literature using electronic libraries (Pub Med, Medline), German veterinary medicine journals and obstetrical textbooks. Uterine torsion is a very important maternal reason for dystocia as most cases occur during parturition. The post-cervical torsion (combined uterine and vaginal torsion, Torsio uteri and vaginae) is more commonly diagnosed than an intra-cervical or pre-cervical torsion. Torsions to the left occur more frequently than to the right. Clinical symptoms clearly vary depending on the degree of torsion. The frequency in relation to all parturitions is described as between 0.5 and 1%, whereas the percentage of uterine torsions presented to the veterinarian as a reason for dystocia varies between 2.7 and 65%. The pathogenesis of uterine torsion remains unclear; however, general agreement exists that the cow is predisposed to uterine torsion due to its anatomy. It appears that the Brown Swiss is more often affected than other cattle breeds.

  1. Electron as the eigenstate of curvilinear space with torsion

    Science.gov (United States)

    Sharin, Yu. A.

    1998-05-01

    Ideas previously enunciated by the author about the physical interpretation of curvilinear space with torsion are developed. With the new equations describing the eigenstates of such a space, the static centrosymmetric solution for gravitational and electric fields can be made consistent with the Newton and Coulomb laws. The asymptotic behavior of the axisymmetric solution at infinity is studied. The gyromagnetic ratio obtained is characteristic of the electron.

  2. A supersymmetric R2-action in six dimensions and torsion

    NARCIS (Netherlands)

    Bergshoeff, E.; Salam, Abdus; Sezgin, E.

    1986-01-01

    The superconformal extension of (Rµνab)2 is given in six dimensions. It is shown that in a superconformal gauge the three-form field Hµν� has a natural torsion interpretation. Also partial results are given on the superconformal extension of the Gauss-Bonnet combination R2µνab - 4R2µa + R2.

  3. Compactification over coset spaces with torsion and vanishing cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Batakis, N.A.; Farakos, K.; Koutsoumbas, G.; Zoupanos, G.; Kapetanakis, D.

    1989-04-13

    We consider the compactification of ten-dimensional Einstein-Yang-Mills theories over non-symmetric, six-dimensional homogeneous coset spaces with torsion. We examine the Einstein-Yang-Mills equations of motion requiring vanishing cosmological constant at ten and four dimensions and we present examples of compactifying solutions. It appears that the introduction of more than one radii in the coset space, when possible, may be mandatory for the existence of compactifying solutions.

  4. Torsional Response of the Offshore Platform with TMD

    Institute of Scientific and Technical Information of China (English)

    江宜城; 唐家祥

    2001-01-01

    It is pointed out in this paper that the offshore platform could be controlled by means of the Tuned Mass Damper(TMD) if there is torsional vibration in the system. The effectiveness of the location of TMD is quantified with the helpof the response ratio between the peak responses of the system in the presence and in the absence of TMD. In addition,the parameters of frequency and damping ratio of TMD are optimized.

  5. Search for Possible Connections of Sunspot Features and Torsional Waves

    CERN Document Server

    Muraközy, J

    2014-01-01

    The torsional oscillation is a well established observational fact and there are theoretical attempts for its description but no final solution has yet been accepted. One of the possible candidates for its cause is the presence of sunspots modifying the streaming conditions. The present work focuses on the temporally varying latitudinal distribution of several sunspot features, such as the spot sizes and spot numbers. These features are different faces of the butterfly diagram. In fact some weak spatial correlations can be recognized.

  6. Spectroscopy in the Presence of Geometrical Constraints: A Torsional Pendulum

    CERN Document Server

    Hancock, J N; Hancock, Jason N.; Schlesinger, Zack

    2004-01-01

    We demonstrate that an effect other than anharmonicity can severely distort the spectroscopic signatures of quantum mechanical systems. This is done through an analytic calculation of the spectroscopic response of a simple system, a charged torsional pendulum. One may look for these effects in the optical data of real systems when for example a significant rocking component of rigid polyhedra plays a significant role in the lattice dynamics.

  7. On Polya's inequality for torsional rigidity and first Dirichlet eigenvalue

    OpenAIRE

    Berg, M. van den; Ferone, V.; Nitsch, C.; Trombetti, C.

    2016-01-01

    Let $\\Omega$ be an open set in Euclidean space with finite Lebesgue measure $|\\Omega|$. We obtain some properties of the set function $F:\\Omega\\mapsto \\R^+$ defined by $$ F(\\Omega)=\\frac{T(\\Omega)\\lambda_1(\\Omega)}{|\\Omega|} ,$$ where $T(\\Omega)$ and $\\lambda_1(\\Omega)$ are the torsional rigidity and the first eigenvalue of the Dirichlet Laplacian respectively. We improve the classical P\\'olya bound $F(\\Omega)\\le 1,$ and show that $$F(\\Omega)\\le 1- \

  8. Upright perception and ocular torsion change independently during head tilt

    Directory of Open Access Journals (Sweden)

    Amir Kheradmand

    2016-11-01

    Full Text Available We maintain a stable perception of the visual world despite continuous movements of our eyes, head and body. Perception of upright is a key aspect of such orientation constancy. Here we investigated whether changes in upright perception during sustained head tilt were related to simultaneous changes in torsional position of the eyes. We used a subjective visual vertical (SVV task, modified to track changes in upright perception over time, and a custom video method to measure ocular torsion simultaneously. We tested twelve subjects in upright position, during prolonged (~15min lateral head tilts of 20 degrees, and also after the head returned to upright position. While the head was tilted, SVV drifted in the same direction as the head tilt (left tilt: -5.4±1.4 o and right tilt: +2.2±2.1 o. After the head returned to upright position, there was an SVV aftereffect with respect to the pre-tilt baseline, which was also in the same direction as the head tilt (left tilt: -3.9±0.6 o and right tilt: +2.55±1.0 o. Neither the SVV drift nor the SVV aftereffect were correlated with the changes in ocular torsion. Using the Bayesian spatial-perception model we show that the pattern of SVV drift and aftereffect in our results could be explained by a drift and an adaptation in sensory inputs that encode head orientation. The fact that ocular torsion (mainly driven by the otoliths could not account for the perceptual changes suggests that neck proprioception could be the primary source of drift in upright perception during head tilt, and subsequently the aftereffect in upright position.

  9. Torsion of the greater omentum: treatment by laparoscopy.

    Science.gov (United States)

    Sánchez, Javier; Rosado, Rafael; Ramírez, Diego; Medina, Pedro; Mezquita, Susana; Gallardo, Andrés

    2002-12-01

    Four new cases of necrosis of the omentum secondary to torsion are reported. We review the associated signs and symptoms, which are usually those of an acute inflammatory condition in the right lower quadrant (RLQ), very similar to acute appendicitis. Because of acute abdominal pain in the RLQ, along with an uncertain diagnosis, laparoscopic surgery was performed in these cases. Laparoscopy demonstrated the existence of the omental infarction and allowed for complete treatment of the condition without the need for laparotomy.

  10. VERIFICATION OF TORSIONAL OSCILLATING MECHANICAL SYSTEM DYNAMIC CALCULATION RESULTS

    OpenAIRE

    2014-01-01

    On our department we deal with optimization and tuning of torsional oscillating mechanical systems. When solving these problems we often use results of dynamic calculation. The goal of this article is to compare values obtained by computation and experimentally. For this purpose, a mechanical system built in our laboratory was used. At first, classical HARDY type flexible coupling has been applied into the system, then we used a pneumatic flexible shaft coupling developed by us...

  11. Damping of Torsional Beam Vibrations by Control of Warping Displacement

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker; Hoffmeyer, David; Ejlersen, Christian

    2016-01-01

    Supplemental damping of torsional beam vibrations is considered by viscous bimoments acting on the axial warping displacement at the beam supports. The concept is illustrated by solving the governing eigenvalue problem for various support configurations with the applied bimoments represented...... as viscous boundary conditions. It is demonstrated that properly calibrated viscous bimoments introduce a significant level of supplemental damping to the targeted vibration mode and that the attainable damping can be accurately estimated from the two undamped problems associated with vanishing and infinite...

  12. Preliminary Results from the Large Volume Torsion (LVT) Deformation Apparatus

    Science.gov (United States)

    Cross, A. J.; Couvy, H.; Skemer, P. A.

    2015-12-01

    We present preliminary results from the Large Volume Torsion (LVT) apparatus, currently under development in the rock deformation lab at Washington University in St. Louis. The LVT is designed to deform disk-shaped samples (~4 mm in diameter) in torsion at lower-crustal to upper-mantle pressure and temperature conditions. Conceptually, the LVT complements and is similar in design to the Rotational Drickamer Apparatus (RDA) (Yamakazi & Karato, 2001), which deforms smaller samples at higher pressures. As part of our recent development efforts, benchmarking experiments were performed on Carrara marble. Samples were deformed in torsion at a strain rate of ~5 x 10-5 s-1 to moderate shear strains (γ ≤ 10) under lower crustal conditions (800°C, 2 GPa confining pressure). Microstructural observations from optical microscopy and electron backscatter diffraction (EBSD) show evidence for relict grain elongation and alignment; an increase in calcite twin density; and grain size reduction concurrent with recrystallized grain nucleation. Microstructural observations are comparable to data obtained from previous studies at lower pressure (e.g. Barnhoorn et al., 2004), confirming that the LVT provides reliable microstructural results.

  13. A gluing formula for the analytic torsion on singular spaces

    CERN Document Server

    Lesch, Matthias

    2012-01-01

    We prove a gluing formula for the analytic torsion on non-compact (i.e. singular) riemannian manifolds. Let M= U\\cup M_1, where M_1 is a compact manifold with boundary and U represents a model of the singularity. For general elliptic operators we formulate a criterion, which can be checked solely on U, for the existence of a global heat expansion, in particular for the existence of the analytic torsion in case of the Laplace operator. The main result then is the gluing formula for the analytic torsion. Here, decompositions M=M_1\\cup_W M_2 along any compact closed hypersurface W with M_1, M_2 both non-compact are allowed; however product structure near W is assumed. We work with the de Rham complex coupled to an arbitrary flat bundle F; the metric on F is not assumed to be flat. In an appendix the corresponding algebraic gluing formula is proved. As a consequence we obtain a framework for proving a Cheeger-M\\"uller type Theorem for singular manifolds; the latter has been the main motivation for this work. The ...

  14. Solar neutrinos, helicity effects and new affine gravity with torsion

    Science.gov (United States)

    Cirilo-Lombardo, Diego Julio

    2013-12-01

    New f(R, T) model of gravitation, introduced previously by the author, is considered. It is based on an affine geometrical construction in which the torsion is a dynamical field, the coupling is minimal and the theory is Lorentz invariant by construction. It was shown that the Dirac equation emerges from the same space time and acquires a modification (coupling-like) of the form γα j 1-d/d γ5hα , with hα the torsion axial vector, j a parameter of pure geometrical nature and d, the spacetime dimension. In the present work it is shown that this interaction produces a mechanism of spin (helicity) flipping, with its consequent weak symmetry violation. The cross section of this process is explicitly calculated and a logarithmic energy dependence (even at high energies) is found. This behavior is reminiscent of similar computations made by Hans Bethe in the context of neutrino astrophysics. These results are applied to the solar neutrino case and compared with similar results coming from a gravitational model with torsion of string theory type and within the standard model context respectively.

  15. Shape sensing for torsionally compliant concentric-tube robots

    Science.gov (United States)

    Xu, Ran; Yurkewich, Aaron; Patel, Rajni V.

    2016-03-01

    Concentric-tube robots (CTR) consist of a series of pre-curved flexible tubes that make up the robot structure and provide the high dexterity required for performing surgical tasks in constrained environments. This special design introduces new challenges in shape sensing as large twisting is experienced by the torsionally compliant structure. In the literature, fiber Bragg grating (FBG) sensors are attached to needle-sized continuum robots for curvature sensing, but they are limited to obtaining bending curvatures since a straight sensor layout is utilized. For a CTR, in addition to bending curvatures, the torsion along the robots shaft should be determined to calculate the shape and pose of the robot accurately. To solve this problem, in our earlier work, we proposed embedding FBG sensors in a helical pattern into the tube wall. The strain readings are converted to bending curvatures and torsion by a strain-curvature model. In this paper, a modified strain-curvature model is proposed that can be used in conjunction with standard shape reconstruction algorithms for shape and pose calculation. This sensing technology is evaluated for its accuracy and resolution using three FBG sensors with 1 mm sensing segments that are bonded into the helical grooves of a pre-curved Nitinol tube. The results show that this sensorized robot can obtain accurate measurements: resolutions of 0.02 rad/m with a 100 Hz sampling rate. Further, the repeatability of the obtained measurements during loading and unloading conditions are presented and analyzed.

  16. Diesel engine torsional vibration control coupling with speed control system

    Science.gov (United States)

    Guo, Yibin; Li, Wanyou; Yu, Shuwen; Han, Xiao; Yuan, Yunbo; Wang, Zhipeng; Ma, Xiuzhen

    2017-09-01

    The coupling problems between shafting torsional vibration and speed control system of diesel engine are very common. Neglecting the coupling problems sometimes lead to serious oscillation and vibration during the operation of engines. For example, during the propulsion shafting operation of a diesel engine, the oscillation of engine speed and the severe vibration of gear box occur which cause the engine is unable to operate. To find the cause of the malfunctions, a simulation model coupling the speed control system with the torsional vibration of deformable shafting is proposed and investigated. In the coupling model, the shafting is simplified to be a deformable one which consists of several inertias and shaft sections and with characteristics of torsional vibration. The results of instantaneous rotation speed from this proposed model agree with the test results very well and are successful in reflecting the real oscillation state of the engine operation. Furthermore, using the proposed model, the speed control parameters can be tuned up to predict the diesel engine a stable and safe running. The results from the tests on the diesel engine with a set of tuned control parameters are consistent with the simulation results very well.

  17. Scalar torsion and a new symmetry of general relativity

    CERN Document Server

    Fonseca-Neto, J B; Martinez, S P G

    2012-01-01

    We reformulate the general theory of relativity in the language of Riemann-Cartan geometry. We start from the assumption that the space-time can be described as a non-Riemannian manifold, which, in addition to the metric field, is endowed with torsion. In this new framework, the gravitational field is represented not only by the metric, but also by the torsion, which is completely determined by a geometric scalar field. We show that in this formulation general relativity has a new kind of invariance, whose invariance group consists of a set of conformal and gauge transformations, called Cartan transformations. These involve both the metric tensor and the torsion vector field, and are similar to the well known Weyl gauge transformations. By making use of the concept of Cartan gauges, we show that, under Cartan transformations, the new formalism leads to different pictures of the same gravitational phenomena. We show that in an arbitrary Cartan gauge general relativity has the form of a scalar-tensor theory. In...

  18. On the torsional loading of elastoplastic spheres in contact

    Science.gov (United States)

    Nadimi, Sadegh; Fonseca, Joana

    2017-06-01

    The mechanical interaction between two bodies involves normal loading in combination with tangential, torsional and rotational loading. This paper focuses on the torsional loading of two spherical bodies which leads to twisting moment. The theoretical approach for calculating twisting moment between two spherical bodies has been proposed by Lubkin [1]. Due to the complexity of the solution, this has been simplified by Deresiewicz for discrete element modelling [2]. Here, the application of a simplified model for elastoplastic spheres is verified using computational modelling. The single grain interaction is simulated in a combined finite discrete element domain. In this domain a grain can deform using a finite element formulation and can interact with other objects based on discrete element principles. For an elastoplastic model, the contact area is larger in comparison with the elastic model, under a given normal force. Therefore, the plastic twisting moment is stiffer. The results presented here are important for describing any granular system involving torsional loading of elastoplastic grains. In particular, recent research on the behaviour of soil has clearly shown the importance of plasticity on grain interaction and rearrangement.

  19. Torsional stiffness degradation and aerostatic divergence of suspension bridge decks

    Science.gov (United States)

    Zhang, Z. T.; Ge, Y. J.; Yang, Y. X.

    2013-07-01

    The mechanism of aerostatic torsional divergence (ATD) of long-span suspension bridges is investigated. A theoretical analysis on the basis of a generalized model is presented, showing that the vertical motion of a bridge deck is crucial to the torsional stiffness of the whole suspended system, and that the vertical motion of either cable with a magnitude beyond a certain threshold could result in a sudden degradation of the torsional stiffness of the system. This vertical motion-induced degradation of stiffness is recognized as the main reason for the ATD. Long-span suspension bridges are susceptible to such a type of divergence, especially when they are immersed in turbulent wind fields. The divergences that occur in turbulent wind fields differ significantly from those in smooth wind fields, and the difference is well explained by the generalized model that the loosening of any one cable could result in the vanishing of the part of stiffness provided by the whole cable system. The mechanism revealed in this paper leads to a definition of the critical wind speed of the ATD in a turbulent flow; that is, the one resulting in a vertical motion so large as to loosen either cable to a stressless state. Numerical results from the nonlinear finite-element (FE) analysis of the Xihoumen suspension bridge, in conjunction with observations from wind tunnel tests on an aero-elastic full bridge model, are in support of the viewpoint presented in this study.

  20. Clinical observation of torsional phacoemulsification for a beginner

    Directory of Open Access Journals (Sweden)

    Qiong Lei

    2013-09-01

    Full Text Available AIM: To observe the clinical security of torsional phacoemulsification for a beginner.METHODS: The clinical data of 200 eyes who accepted torsional phacoemulsification by a beginner from February 2012 to March 2013 were reviewed. The operation complications were analyzed and the postoperative effect was assessed.RESULTS: There was no collapse of the anterior chamber during operation. When the last nuclear was removed the surge occurred mildly. Posterior capsular rupture happened in 8 eyes, 5 eyes' intraocular lens#IOL#implanted in sclera sulcus after anterior vitrectomy, 3 eyes' IOL in bag without vitreous outflow. One eye without continuous curvilinear capsulotomy was transferred to the superior doctor for extracapsular cataract extraction#ECCE#. One eye with the loose zonular fiber was implanted a capsular tension ring by the superior doctor. Seven cases need suture because of short sclera tunnel incisions. Uncorrected visual acuity a week after operation: 2 eyes#1%#CONCLUSION: The technique of torsional phacoemulsification is safe and effective for a beginner.

  1. On discrete symmetries and torsion homology in F-theory

    Energy Technology Data Exchange (ETDEWEB)

    Mayrhofer, Christoph [Arnold-Sommerfeld-Center, Ludwig-Maximilians-Universität München,München (Germany); Palti, Eran; Till, Oskar; Weigand, Timo [Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg,Heidelberg (Germany)

    2015-06-04

    We study the relation between discrete gauge symmetries in F-theory compactifications and torsion homology on the associated Calabi-Yau manifold. Focusing on the simplest example of a ℤ{sub 2} symmetry, we show that there are two physically distinct ways that such a discrete gauge symmetry can arise. First, compactifications of M-Theory on Calabi-Yau threefolds which support a genus-one fibration with a bi-section are known to be dual to six-dimensional F-theory vacua with a ℤ{sub 2} gauge symmetry. We show that the resulting five-dimensional theories do not have a ℤ{sub 2} symmetry but that the latter emerges only in the F-theory decompactification limit. Accordingly the genus-one fibred Calabi-Yau manifolds do not exhibit torsion in homology. Associated to the bi-section fibration is a Jacobian fibration which does support a section. Compactifying on these related but distinct varieties does lead to a ℤ{sub 2} symmetry in five dimensions and, accordingly, we find explicitly an associated torsion cycle. We identify the expected particle and membrane system of the discrete symmetry in terms of wrapped M2 and M5 branes and present a field-theory description of the physics for both cases in terms of circle reductions of six-dimensional theories. Our results and methods generalise straightforwardly to larger discrete symmetries and to four-dimensional compactifications.

  2. Reaching the limit of the oculomotor plant: 3D kinematics after abducens nerve stimulation during the torsional vestibulo-ocular reflex.

    Science.gov (United States)

    Klier, Eliana M; Meng, Hui; Angelaki, Dora E

    2012-09-19

    Accumulating evidence shows that the oculomotor plant is capable of implementing aspects of three-dimensional kinematics such as Listing's law and the half-angle rule. But these studies have only examined the eye under static conditions or with movements that normally obey these rules (e.g., saccades and pursuit). Here we test the capability of the oculomotor plant to rearrange itself as necessary for non-half-angle behavior. Three monkeys (Macaca mulatta) fixated five vertically displaced targets along the midsagittal plane while sitting on a motion platform that rotated sinusoidally about the naso-occipital axis. This activated the torsional, rotational vestibulo-ocular reflex, which exhibits a zero-angle or negative-angle rule (depending on the visual stimulus). On random sinusoidal cycles, we stimulated the abducens nerve and observed the resultant eye movements. If the plant has rearranged itself to implement this non-half-angle behavior, then stimulation should reveal this behavior. On the other hand, if the plant is only capable of half-angle behavior, then stimulation should reveal a half-angle rule. We find the latter to be true and therefore additional neural signals are likely necessary to implement non-half-angle behavior.

  3. NASA/University JOint VEnture (JOVE) Program: Transverse Shear Moduli Using the Torsional Responses of Rectangular Laminates

    Science.gov (United States)

    Bogan, Sam

    2001-01-01

    The first year included a study of the non-visible damage of composite overwrapped pressure vessels with B. Poe of the Materials Branch of Nasa-Langley. Early determinations showed a clear reduction in non-visible damage for thin COPVs when partially pressurized rather than unpressurized. Literature searches on Thicker-wall COPVs revealed surface damage but clearly visible. Analysis of current Analytic modeling indicated that that current COPV models lacked sufficient thickness corrections to predict impact damage. After a comprehensive study of available published data and numerous numerical studies based on observed data from Langley, the analytic framework for modeling the behavior was determined lacking and both Poe and Bogan suggested any short term (3yr) result for Jove would be overly ambitious and emphasis should be placed on transverse shear moduli studies. Transverse shear moduli determination is relevant to the study of fatigue, fracture and aging effects in composite structures. Based on the techniques developed by Daniel & Tsai, Bogan and Gates determined to verify the results for K3B and 8320. A detailed analytic and experimental plan was established and carried out that included variations in layup, width, thickness, and length. As well as loading rate variations to determine effects and relaxation moduli. The additional axial loads during the torsion testing were studied as was the placement of gages along the composite specimen. Of the proposed tasks, all of tasks I and 2 were completed with presentations given at Langley, SEM conferences and ASME/AIAA conferences. Sensitivity issues with the technique associated with the use of servohydraulic test systems for applying the torsional load to the composite specimen limited the torsion range for predictable and repeatable transverse shear properties. Bogan and Gates determined to diverge on research efforts with Gates continuing the experimental testing at Langley and Bogan modeling the apparent non

  4. Photoelectric angle converter

    Science.gov (United States)

    Podzharenko, Volodymyr A.; Kulakov, Pavlo I.

    2001-06-01

    The photo-electric angle transmitter of rotation is offered, at which the output voltage is linear function of entering magnitude. In a transmitter the linear phototransducer is used on the basis of pair photo diode -- operating amplifier, which output voltage is linear function of the area of an illuminated photosensitive stratum, and modulator of a light stream of the special shape, which ensures a linear dependence of this area from an angle of rotation. The transmitter has good frequent properties and can be used for dynamic measurements of an angular velocity and angle of rotation, in systems of exact drives and systems of autocontrol.

  5. A method of measuring micro-impulse with torsion pendulum based on multi-beam laser heterodyne

    Institute of Scientific and Technical Information of China (English)

    Li Yan-Chao; Wang Chun-Hui

    2012-01-01

    In this paper,we propose a novel method of multi-beam laser heterodyne measurement for micro-impulse.The measurement of the micro-impulse,which is converted into the measurement of the small tuning angle of the torsion pendulum,is realized by considering the interaction between pulse laser and working medium.Based on Doppler effect and heterodyne technology,the information regarding the small tuning angle is loaded to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror,thereby obtaining many values of the small tuning angle after the multi-beam laser heterodyne signal demodulation simultaneously.Processing these values by weighted-average,the small tuning angle can be obtained accurately and the value of the micro-impulse can eventually be calculated.Using Polyvinylchlorid+2%C as a working medium,this novel method is used to simulate the value of the micro-impulse by MATLAB which is generated by considering the interaction between the pulse laser and the working medium,the obtained result shows that the relative error of this method is just 0.5%.

  6. Torsion sensing characteristics of long period fiber gratings fabricated by femtosecond laser in optical fiber

    Science.gov (United States)

    Duan, Ji'an; Xie, Zheng; Wang, Cong; Zhou, Jianying; Li, Haitao; Luo, Zhi; Chu, Dongkai; Sun, Xiaoyan

    2016-09-01

    With the alignment of the fiber core systems containing dual-CCDs and high-precision electric displacement platform, twisted long period fiber gratings (T-LPFGs) were fabricated in two different twisted SMF-28 fibers by femtosecond laser. The torsion characteristics of the T-LPFGs were experimentally and theoretical investigated and demonstrated in this study. The achieved torsion sensitivity is 117.4 pm/(rad/m) in the torsion range -105-0 rad/m with a linearity of 0.9995. Experimental results show that compared with the ordinary long period fiber gratings, the resonance wavelength of the gratings presents an opposite symmetrical shift depending on the twisting direction after the applied torsion is removed. In addition, high sensitivity could be obtained, which is very suitable for the applications in the torsion sensor. These results are important for the design of new torsion sensors based on T-LPFGs fabricated by femtosecond laser.

  7. Pemodelan, Pengujian, dan Analisis Getaran Torsional dari Perangkat Uji Sistem Poros-Rotor

    Directory of Open Access Journals (Sweden)

    Zainal Abidin

    2008-01-01

    Full Text Available Vibrations of rotating machinary can be classified as translational and rotational. The vibrations occurred in rotational direction are commonly classified as torsional vibration. Torsional vibration can cause fatigue damage of shaft, coupling, or gear. In this paper, a method for measuring torsional vibration is proposed. This method uses two incremental encoders and an algorithm to process the data. To show its effectiveness, the method was implemented to measure torsional vibration of a rotor shaft system. The paper also shows the torsional vibration characteristics of of the system. To predict the torsional natural frequencies of the system, a finite elemen model was developed using Ansys Workbench 11 and the results was validite using a torsional FRF test. The measurement was performed a range of rotational speed to enable a spectral map can be constructed. There were two types of flexible couplings used in this work, a hose coupling and a rubber jaw coupling. The results of the experiment show that the proposed method can be implemented very well to measure the torsional vibration of the rotor shaft-system. In addition, the torsional vibration of the rotor shaft system has a similar characteristics to that of translational vibration, in which vibration signal is dominated by component with frequency of 1xRPM. The results also show that the level of torsional vibration depends on the type of flexible coupling being used. Due to low torsional stiffness, hose coupling produce low natural frequencies than those of jaw coupling. As a consequence, hose coupling are liable to higher vibration than jaw coupling. Abstract in Bahasa Indonesia: Getaran yang terjadi pada mesin dapat berupa getaran translasi maupun rotasi. Getaran yang terjadi dalam arah rotasi sering disebut sebagai getaran torsional. Getaran torsional dapat mengakibatkan terjadinya gagal lelah pada poros, kopling, maupun roda gigi. Dalam makalah ini, diusulkan sebuah metode

  8. Primordial magnetic fields of non-minimal photon-torsion axial coupling origin

    CERN Document Server

    de Andrade, Garcia

    2010-01-01

    Dynamo action is shown to be induced from homogeneous non-minimal photon-torsion axial coupling in the quantum electrodynamics (QED) framework in Riemann flat spacetime contortion decays. The geometrical optics in Riemann-Cartan spacetime is considering and a plane wave expansion of the electromagnetic vector potential is considered leading to a set of the equations for the ray congruence. Since we are interested mainly on the torsion effects in this first report we just consider the Riemann-flat case composed of the Minkowskian spacetime with torsion. It is also shown that in torsionic de Sitter background the vacuum polarisation does alter the propagation of individual photons, an effect which is absent in Riemannian spaces. It is shown that the cosmological torsion background inhomogeneities induce Lorentz violation and massive photon modes in this QED. Magnetic dynamos in this torsioned spacetime electrodynamics are simpler obtained in Fourier space than the cosmic ones, previously obtained by Bassett et ...

  9. Rovibrational molecular hamiltonian in mixed bond-angle and umbrella-like coordinates.

    Science.gov (United States)

    Makarewicz, Jan; Skalozub, Alexander

    2007-08-16

    A new exact quantum mechanical rovibrational Hamiltonian operator for molecules exhibiting large amplitude inversion and torsion motions is derived. The derivation is based on a division of a molecule into two parts: a frame and a top. The nuclei of the frame only are used to construct a molecular system of axes. The inversion motion of the frame is described in the umbrella-like coordinates, whereas the torsion motion of the top is described by the nonstandard torsion angle defined in terms of the nuclear vectors and one of the molecular axes. The internal coordinates chosen take into account the properties of the inversion and torsion motions. Vibrational s and rotational Omega vectors obtained for the introduced internal coordinates determine the rovibrational tensor G defined by simple scalar products of these vectors. The Jacobian of the transformation from the Cartesian to the internal coordinates considered and the G tensor specify the rovibrational Hamiltonian. As a result, the Hamiltonian for penta-atomic molecules like NH2OH with one inverter is presented and a complete set of the formulas necessary to write down the Hamiltonian of more complex molecules, like NH2NH2 with two inverters, is reported. The approach considered is essentially general and sufficiently simple, as demonstrated by derivation of a polyatomic molecule Hamiltonian in polyspherical coordinates, obtained by other methods with much greater efforts.

  10. Angle-Ply Weaving

    Science.gov (United States)

    Farley, Gary L.

    1990-01-01

    Bias-direction or angle-ply weaving is proposed new process for weaving fibers along bias in conventional planar fabric or in complicated three-dimensional multilayer fabric preform of fiber-reinforced composite structure. Based upon movement of racks of needles and corresponding angle yarns across fabric as fabric being formed. Fibers woven along bias increases shear stiffness and shear strength of preform, increasing value of preform as structural member.

  11. Effective coarse-grained simulations of super-thick multi-walled carbon nanotubes under torsion

    OpenAIRE

    Jian, Zou; Huang, Xu; Arroyo Balaguer, Marino; Zhang, Sulin

    2009-01-01

    Under torsion and beyond the buckling point, multi-walled carbon nanotubes (MWCNTs) develop a periodic wave-like rippling morphology. Here, we show that torsional rippling deformations can be accurately described by a simple sinusoidal shape function. Combining this observation with the geometry optimization, we develop an effective coarse-grained model that reproduces the complex nonlinear mechanical responses of thick MWCNTs under torsion predicted by large-scale atomistic simulations. Furt...

  12. Acute torsion of a retroperitoneal renal transplant mimicking renal vein thrombosis.

    Science.gov (United States)

    Winter, Thomas C; Clarke, Andrea Lynn; Campsen, Jeffrey

    2013-09-01

    When imaging a renal transplant, the combination of absent flow in the main renal vein and reversed diastolic flow in the intrarenal arteries is considered highly suggestive of renal vein thrombosis. We present a case of torsion of a transplant kidney presenting with identical findings. Renal transplant torsion in general is a rare entity, previously described only in intraperitoneally placed organs; this case is the first that we are aware of with torsion occurring in a retroperitoneally placed graft.

  13. Mechanically-Assisted Current-Induced Switching of the Magnetic Moment in a Torsional Oscillator

    OpenAIRE

    Cai, Liufei; Jaafar, Reem; Chudnovsky, Eugene M.

    2014-01-01

    Switching of the direction of the magnetic moment in a nanomagnet is studied within a modified Slonczewski's model that permits torsional oscillations of the magnet. We show that the latter may inhibit or assist the magnetization switching, depending on parameters. Three regimes have been studied: the switching by torsional oscillations alone, the switching by the spin-polarized current with torsional oscillations permitted, and the magnetization switching by the current combined with the mec...

  14. Torsional properties of hexagonal boron nitride nanotubes, carbon nanotubes and their hybrid structures: A molecular dynamics study

    Directory of Open Access Journals (Sweden)

    Qi-lin Xiong

    2015-10-01

    Full Text Available The torsional mechanical properties of hexagonal single-walled boron nitride nanotubes (SWBNNTs, single-walled carbon nanotubes (SWCNTs, and their hybrid structures (SWBN-CNTs are investigated using molecular dynamics (MD simulation. Two approaches - force approach and energy approach, are adopted to calculate the shear moduli of SWBNNTs and SWCNTs, the discrepancy between two approaches is analyzed. The results show that the shear moduli of single-walled nanotubes (SWNTs, including SWBNNTs and SWCNTs are dependent on the diameter, especially for armchair SWNTs. The armchair SWNTs show the better ability of resistance the twisting comparable to the zigzag SWNTs. The effects of diameter and length on the critical values of torque of SWNTs are obtained by comparing the torsional behaviors of SWNTs with different diameters and different lengths. It is observed that the MD results of the effect of diameter and length on the critical values of torque agrees well with the prediction of continuum shell model. The shear modulus of SWBN-CNT has a significant dependence on the percentages of SWCNT and the hybrid style has also an influence on shear modulus. The critical values of torque of SWBN-CNTs increase with the increase of the percentages of SWCNT. This phenomenon can be interpreted by the function relationship between the torque of different bonds (B-N-X, C-C-X, C-B-X, C-N-X and the angles of bonds.

  15. Damping Torsional Torques in Turbine-Generator Shaft by Novel PSS Based on Genetic Algorithm and Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    Abbas Shoulaie

    2010-07-01

    Full Text Available Torsional torques on turbine-generator shaft which are yields of disturbances in power systems, can reduce the useful lifetime of shaft. In this paper, these oscillations will be damped and controlled by novel Power System Stabilizers (PSSs. Complex PSS which is used in this paper will act on the excitation system in generator set and also on the controller of in High Voltage Direct Current (HVDC system. This PSS uses three terms (generator angle deviation, frequency oscillation and capacitor voltage deviation in HVDC system of the study system which includes two ties AC and DC. This is the reason that this PSS is named novel one against the conventional PSSs. In order to adjust the PSS parameters to damp the oscillations, genetic algorithm is used. To improve the application of this PSS, fuzzy logic control methods are also used which has notable effect on controlling the oscillations in study system. The simulation results show the effectiveness of designed PSS in controlling the torsional torques in turbine-generator shaft.

  16. Wing-pitch modulation in maneuvering fruit flies is explained by an interplay between aerodynamics and a torsional spring

    Science.gov (United States)

    Beatus, Tsevi; Cohen, Itai

    2015-11-01

    While the wing kinematics of many flapping insects have been well characterized, understanding the underlying physiological mechanisms that determine these kinematics is still a challenge. Two of the main difficulties arise from the complexity of the interaction between a flapping wing and its own unsteady flow, as well as the intricate mechanics the insect wing-hinge, which is among the most complicated joints in the animal kingdom. These difficulties call for the application of reduced-order approaches. Here, we model the torques exerted by the wing-hinge along the wing-pitch axis of maneuvering fruit flies as a damped torsional spring with elastic and damping coefficients as well as a rest angle. Furthermore, we model the air flows using simplified quasi-static aerodynamics. Our findings suggest that flies take advantage of the passive coupling between aerodynamics and the damped torsional spring to indirectly control their wing-pitch kinematics by modulating the spring damping and elastic coefficients. These results, in conjunction with the previous literature, indicate flies can accurately control their wing-pitch kinematics on a sub-wing-beat time-scale by modulating all three effective spring parameters on longer time-scales.

  17. Unusual cause of acute abdominal pain in a postmenopausal woman: adnexal torsion

    Directory of Open Access Journals (Sweden)

    Alper Biler

    2016-03-01

    Full Text Available Adnexal torsion is an infrequent but significant cause of acute lower abdominal pain in women. While adnexal torsion is generally considered in premenopausal women presenting with acute abdominal pain and a pelvic mass, it is a rare cause of acute abdominal pain during postmenopausal period. The diagnosis of adnexal torsion is often challenging due to nonspesific clinical, laboratory and physical examination findings. Causes of adnexal torsion is also different in premenopausal and postmenopausal women. While a simple functional cyst is often the cause of torsion in premenopausal women, it is more rarely the cause in postmenopausal women. Adnexal torsion is a surgical emergency. The surgery of adnexal torsion is performed either via conventional exploratory laparotomy or laparoscopic surgery. Adnexal torsion in postmenopausal women should be considered not only in the setting of sudden onset pain, but also in long-term abdominal discomfort. In this article, we presented a case with adnexal torsion that rarely cause acute abdominal pain in postmenopausal women. [Cukurova Med J 2016; 41(1.000: 167-170

  18. Gravitational waves and magnetic monopoles during inflation with Weitzenb\\"ock torsion

    CERN Document Server

    Romero, Jesús Martín; Aguilar, José Edgar Madriz

    2016-01-01

    We study the variational principle on a Hilbert-Einstein action in an extended geometry with torsion taking into account non-trivial boundary conditions. We obtain an effective energy-momentum tensor that has its source in the torsion, which represents the matter geometrically induced. We explore about the existence of magnetic monopoles and gravitational waves in this torsional geometry. We conclude that the boundary terms can be identified as possible sources for the cosmological constant and torsion as the source of magnetic monopoles. We examine an example in which gravitational waves are produced during a de Sitter inflationary expansion of the universe.

  19. Tibial torsion in non-arthritic Indian adults: A computer tomography study of 100 limbs

    Directory of Open Access Journals (Sweden)

    Mullaji Arun

    2008-01-01

    Full Text Available Background: Knowledge of normal tibial torsion is mandatory during total knee replacement (TKR, deformity correction and fracture management of tibia. Different values of tibial torsion have been found in different races due to biological and mechanical factors. Value of normal tibial torsion in Indian limbs is not known, hence this study to determine the norm of tibial torsional value in normal Indian population. Materials and Methods: Computer tomography (CT scans were performed in 100 non-arthritic limbs of 50 Indian adults (42 males, eight females; age 26-40 years. Value of tibial torsion was measured using dorsal tangent to tibial condyles proximally and bimalleolar axis distally. Results: Normal tibial torsion was found to be 21.6 ± 7.6 (range 4.8 to 39.5 with none of the values in internal rotation. Right tibia was externally rotated by 2 degrees as compared to the left side ( P 0.029. No significant difference was found in male and female subjects. Value of tibial torsion was less than in Caucasian limbs, but was comparable to Japanese limbs when studies using similar measurement technique were compared. Conclusions: Indian limbs have less tibial torsion than Caucasian limbs but the value of tibial torsion is comparable to Japanese limbs.

  20. Influence of Microstructures and Textures on the Torsional Behavior of Pearlitic Wires

    Institute of Scientific and Technical Information of China (English)

    Yandong LIU; Qiwu JIANG; Gang WANG; Yandong WANG; A.Tidu; Liang ZUO

    2005-01-01

    The microstructure, texture characteristics and torsion ability of two kinds of steel wires were investigated. The eutectoid steel wires were produced by hot and cold drawing with severe deformation. The torsinability of steel wires was measured under two cases, i.e. there exists either fiber texture or circular texture. The results showed that the torsional behavior of the steel wires was affected by their textures and microstructures. The {110} circular texture weakened the torsion ability of the wires. The torsion fracture behavior of {110} texture wires is related to the fact that only two slip systems were activated under simple shear strain deformation.

  1. Running coupling in electroweak interactions of leptons from f(R)-gravity with torsion

    CERN Document Server

    Capozziello, Salvatore; Fabbri, Luca; Vignolo, Stefano

    2012-01-01

    The f(R)-gravitational theory with torsion is considered for one family of leptons; it is found that the torsion tensor gives rise to interactions having the structure of the weak forces while the intrinsic non-linearity of the f(R) function provides an energy-dependent coupling: in this way, torsional f(R) gravity naturally generates both structure and strength of the electroweak interactions among leptons. This implies that the weak interactions among the lepton fields could be addressed as a geometric effect due to the interactions among spinors induced by the presence of torsion in the most general f(R) gravity. Phenomenological considerations are addressed.

  2. Running coupling in electroweak interactions of leptons from f(R)-gravity with torsion

    Energy Technology Data Exchange (ETDEWEB)

    Capozziello, Salvatore; De Laurentis, Mariafelicia [Universita di Napoli ' ' Federico II' ' , Dipartimento di Scienze Fisiche, Napoli (Italy); INFN Sez. di Napoli, Napoli (Italy); Fabbri, Luca [Universita di Genova, DIPTEM Sez. Metodi e Modelli Matematici, Genova (Italy); INFN Sez. di Bologna, Bologna (Italy); Universita di Bologna, Dipartimento di Fisica, Bologna (Italy); Vignolo, Stefano [Universita di Genova, DIPTEM Sez. Metodi e Modelli Matematici, Genova (Italy)

    2012-02-15

    The f(R)-gravitational theory with torsion is considered for one family of leptons; it is found that the torsion tensor gives rise to interactions having the structure of the weak forces, while the intrinsic non-linearity of the f(R) function provides an energy-dependent coupling: in this way, torsional f(R) gravity naturally generates both structure and strength of the electroweak interactions among leptons. This implies that the weak interactions among the lepton fields could be addressed as a geometric effect due to the interactions among spinors induced by the presence of torsion in the most general f(R) gravity. Phenomenological considerations are given. (orig.)

  3. Torsional torque suppression of decentralized generators using H{sub {infinity}} observer

    Energy Technology Data Exchange (ETDEWEB)

    Omine, Eitaro; Goya, Tomonori; Akie, Uehara; Senjyu, Tomonobu; Yona, Atsushi; Urasaki, Naomitsu [Faculty of Engineering, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami, Okinawa 903-0213 (Japan); Funabashi, Toshihisa [Meidensha Corporation, ThinkPark Tower, 2-1-1 Ohsaki, Shinagawa-ku, Tokyo 141-6029 (Japan)

    2010-09-15

    The output power fluctuations of renewable energy plants such as wind turbine generators and photovoltaic systems cause frequency deviations and terminal voltage fluctuations. Furthermore, these power fluctuations also affect the turbine shaft of diesel generator and gas-turbine generators which are usually the main electric power systems in isolated islands. This paper presents a control strategy that achieves torsional torque suppression and power system stabilization. Since the measurement of the torsional torque is technically difficult and there is uncertainty in mechanical constants of the shaft torsional system, the torsional torque is estimated by using a H{sub {infinity}} observer. The simulation results validate the effectiveness of the proposed control system. (author)

  4. Gravitational waves and magnetic monopoles during inflation with Weitzenböck torsion

    Science.gov (United States)

    Romero, Jesús Martín; Bellini, Mauricio; Aguilar, José Edgar Madriz

    2016-09-01

    We study the variational principle on a Hilbert-Einstein action in an extended geometry with torsion taking into account non-trivial boundary conditions. We obtain an effective energy-momentum tensor that has its source in the torsion, which represents the matter geometrically induced. We explore about the existence of magnetic monopoles and gravitational waves in this torsional geometry. We conclude that the boundary terms can be identified as possible sources for the cosmological constant and torsion as the source of magnetic monopoles. We examine an example in which gravitational waves are produced during a de Sitter inflationary expansion of the universe.

  5. An investigation on the behaviour and stiffness of reinforced concrete slabs subjected to torsion

    Science.gov (United States)

    Nguyen, M. C. T.; Pham, P. T.

    2017-01-01

    This paper presents an investigation on RC slab under torsion, by both experiment and finite element analysis. The torsion tests were done on three similar square RC slabs with dimensions of 1900×1900×150 mm. The behaviour of slabs at pre-cracking and post-cracking of concrete phases were investigated, via Load-displacement, twisting moment-curvature relationships, and torsional stiffness of slabs. The experimental results are compared with the FEA and the results in literatures. The torsional stiffness of slab at the phase of concrete cracked and steel yield is about 1/25 of the stiffness at the pre-cracking phase.

  6. Adnexal Torsion with Dystrophic Calcifications in an Adolescent: A Chronic Entity?

    Directory of Open Access Journals (Sweden)

    Pinar Solmaz Hasdemir

    2013-01-01

    Full Text Available Intermittent pelvic pain caused by ovarian cysts in adolescence may be due to torsion or partial torsion of the ovary. We present a case of 18-year old adolescent with symptomatic left ovarian torsion with calcifications demonstrated by pelvic MRI and ultrasonography prior to surgery. The pathologic investigation demonstrated dystrophic calcifications. We speculated that the pattern of the intermittent pain in the story of the patient and the dystrophic calcifications in pathologic investigation which is thought that it might have been potentially developed as a result of chronic hypoxia due to intermittent partial torsions over a period of two years.

  7. Refinement of the Sugar-Phosphate Backbone Torsion Beta for AMBER Force Fields Improves the Description of Z- and B-DNA.

    Science.gov (United States)

    Zgarbová, Marie; Šponer, Jiří; Otyepka, Michal; Cheatham, Thomas E; Galindo-Murillo, Rodrigo; Jurečka, Petr

    2015-12-01

    Z-DNA duplexes are a particularly complicated test case for current force fields. We performed a set of explicit solvent molecular dynamics (MD) simulations with various AMBER force field parametrizations including our recent refinements of the ε/ζ and glycosidic torsions. None of these force fields described the ZI/ZII and other backbone substates correctly, and all of them underpredicted the population of the important ZI substate. We show that this underprediction can be attributed to an inaccurate potential for the sugar-phosphate backbone torsion angle β. We suggest a refinement of this potential, β(OL1), which was derived using our recently introduced methodology that includes conformation-dependent solvation effects. The new potential significantly increases the stability of the dominant ZI backbone substate and improves the overall description of the Z-DNA backbone. It also has a positive (albeit small) impact on another important DNA form, the antiparallel guanine quadruplex (G-DNA), and improves the description of the canonical B-DNA backbone by increasing the population of BII backbone substates, providing a better agreement with experiment. We recommend using β(OL1) in combination with our previously introduced corrections, εζ(OL1) and χ(OL4), (the combination being named OL15) as a possible alternative to the current β torsion potential for more accurate modeling of nucleic acids.

  8. Molecular Symmetry Analysis of Low-Energy Torsional and Vibrational States in the S_{0} and S_{1} States of p-XYLENE to Interpret the Rempi Spectrum

    Science.gov (United States)

    Groner, Peter; Gardner, Adrian M.; Tuttle, William Duncan; Wright, Timothy G.

    2017-06-01

    The electronic transition S_{1} ← S_{0} of p-xylene (pXyl) has been observed by REMPI spectroscopy. Its analysis required a detailed investigation of the molecular symmetry of pXyl whose methyl groups are almost free internal rotors. The molecular symmetry group of pXyl has 72 operators. This group, called [33]D_{2h}, is isomorphic to G_{36}(EM), the double group for ethane and dimethyl acetylene even though it is NOT a double group for pXyl. Loosely speaking, the group symbol, [33]D_{2h}, indicates that is for a molecule with two threefold rotors on a molecular frame with D_{2h} point group symmetry. The transformation properties of the (i) free internal rotor basis functions for the torsional coordinates, (ii) the asymmetric rotor (Wang) basis functions for the Eulerian angles, (iii) nuclear spin functions, (iv) potential function, and (v) transitions dipole moment functions were determined. The forms of the torsional potential in the S_{0} and S_{1} states and the dependence of the first order torsional splittings on the potential coefficients have been obtained. AM Gardner, WD Tuttle, P. Groner, TG Wright, J. Chem. Phys., submitted Dec 2016 P Groner, JR Durig, J. Chem. Phys., 66 (1977) 1856 PR Bunker, P Jensen, Molecular Symmetry and Spectroscopy (1998, NRC Research Press, Ottawa, 2nd ed.)

  9. Focal point analysis of torsional isomers of acrylic acid

    Science.gov (United States)

    Alev Çiftçioğlu, Gökçen; Trindle, Carl; Yavuz, Ilhan

    2010-10-01

    The thermochemistry of acrylic acid has presented challenges owing to its high reactivity, tendency to dimerize in the gas phase, and the existence of two very nearly equal energy conformational isomers. Well-tested thermochemical schemes including G2, G3, G4, and CBS-QB3 agree in the prediction that the s-cis syn structure is the most stable of the torsional isomers, with the s-cis anti form lying 3 kJ mol-1 or less higher in energy. Microwave spectra suggest a value of 0.63 kJ mol-1. The energy barrier between these forms is in the neighbourhood of 25 kJ mol-1 according to a MP2/cc-pVDZ calculation. We present estimates of the relative energies of all four torsional isomers and the rotational barrier based on a variant of the Focal Point Analysis developed by Császár and co-workers. These calculations, extending to the CCSD(T)/cc-pV5Z level, predict that the s-cis anti torsional isomer is the most stable form, in contrast to prior estimates. The s-cis syn form lies about 2.9 kJ mol-1 higher, while the s-trans syn and anti forms lie at about 21.7 and 23.3 kJ mol-1, respectively. We estimate the rotational barrier between the s-cis trans and s-cis anti structures to be about 23.9 kJ mol-1. Error ranges derived from the fit to extrapolation forms suggest that our estimates have an uncertainty of about 0.1 kJ mol-1.

  10. Limited Angle Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho Kyung; Cho, Min Kook; Kim, Seong Sik [Pusan National University, Busan (Korea, Republic of)

    2007-07-01

    In computed tomography (CT), many situations are restricted to obtain enough number of projections or views to avoid artifacts such as streaking and geometrical distortion in the reconstructed images. Speed of motion of an object to be imaged can limit the number of views. Cardiovascular imaging is a representative example. Size of an object can also limit the complete traverse motion or geometrical complexity can obscure to be imaged at certain range of angles. These situations are frequently met in industrial nondestructive testing and evaluation. Dental CT also suffers from similar situation because cervical spine causes less x-ray penetration from some directions such that the available information is not sufficient for standard reconstruction algorithms. The limited angle tomography is now greatly paid attention as a new genre in medical and industrial imaging, popularly known as digital tomosynthesis. In this study, we introduce a modified filtered backprojection method in limited angle tomography and demonstrate its application for the dental imaging.

  11. [The functional sport shoe parameter "torsion" within running shoe research--a literature review].

    Science.gov (United States)

    Michel, F I; Kälin, X; Metzger, A; Westphal, K; Schweizer, F; Campe, S; Segesser, B

    2009-12-01

    Within the sport shoe area torsion is described as the twisting and decoupling of the rear-, mid- and forefoot along the longitudinal axis of the foot. Studies have shown that running shoes restrict the torsion of the foot and thus they increase the pronation of the foot. Based on the findings, it is recommended to design running shoes, which allow the natural freedom of movement of the foot. The market introduction of the first torsion concept through adidas(R) took place in 1989. Independently of the first market introduction, only one epidemiological study was conducted in the running shoe area. The study should investigate the occurrence of Achilles tendon problems of the athletes running in the new "adidas Torsion(R) shoes". However, further studies quantifying the optimal region of torsionability concerning the reduction of injury incidence are still missing. Newer studies reveal that the criterion torsion only plays a secondary roll regarding the buying decision. Moreover, athletes are not able to perceive torsionability as a discrete functional parameter. It is to register, that several workgroups are dealing intensively with the detailed analysis of the foot movement based on kinematic multi-segment-models. However, scientific as well as popular scientific contributions display that the original idea of the torsion concept is still not completely understood. Hence, the "inverse" characteristic is postulated. The present literature review leads to the deduction that the functional characteristics of the torsion concept are not fully implemented within the running shoe area. This implies the necessity of scientific studies, which investigate the relevance of a functional torsion concept regarding injury prevention based on basic and applied research. Besides, biomechanical studies should analyse systematically the mechanism and the effects of torsion relevant technologies and systems.

  12. The study about torsional vibration charateristics and its optimization of vehicle transmission system

    Science.gov (United States)

    Huang, Yuxin; Xin, Qinkun; Yin, Huabing

    2010-06-01

    The torsional vibration of vehicle transmission system is heavily concerned with the increase of vehicle speed. The whole powertrain system has to be matched according to the torsional vibration characteristics, especially in developing a new vehicle. The selection of proper elastic coupling has to be made for the torsional vibration match and some frequencies have to be moved out of engine's range . Thus the torsional vibration model of powertrain needs to be built. In the paper a new torsional vibration model is built, which is programmed in the form of a platform. The whole powertrain system torsional vibration model of a vehicle is built firstly with consideration of gear mesh stiffness and engine's excitation in it. The free torsional vibration mode analysis is made and the resonant torques of each lumped inertia in the transmission system are obtained. Secondly the forced vibration of transmission system with the engine's excitation is made and the dynamic torques of each lumped inertias are obtained. Thirdly the process for the torsional vibration analysis is integrated into the optimization process and the selection of elastic coupling for the transmission system is made according the optimization and match results. Fourthly in order to modify the design parameters in the structural design, the sensitivities of inertia and torsional stiffness with reference to eigenvalues are obtained. At last the evaluations of analysis results are made and some suggestions for structural modification for engineers are presented. According to the above study, the conclusion can be made that the new torsional modelling method, the elastic coupling selection method and integration optimization method in the paper are practical and reliabl and these methods play very important roles in torsional vibration analyzing, match and optimization of vehicle transmission system.

  13. Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex

    Science.gov (United States)

    Trillenberg, P.; Shelhamer, M.; Roberts, D. C.; Zee, D. S.

    2003-01-01

    The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head

  14. Cyclic Stress-Strain Studies of Metals in Torsion

    Science.gov (United States)

    1940-12-01

    give a uniform stress distribution for th,at part of the specimen .on which the twist uas measured. IQ the cyclic” torsion tests data for a shearing...In the tensile and the, com- pressive tests, strains, were measured, over 2-i.~h g-e leugths usiag the I.larteLnsmirror .= tensometer - ~?hree-iach gage...considered. thus far.., Except foy the ~irst part of the firs”t cz?cle, a li~e~~ relati-onship between shearing stress aad strain was not obtained”. What

  15. Torsional dynamics and orientation of DNA-DAPI complexes

    OpenAIRE

    Barcellona, ML; Gratton, E

    1996-01-01

    The flexibility of calf thymus DNA and several polynucleotides was measured using the anisotropy decay of DAPI bound to DNA, a minor groove probe. DNA torsional dynamics were analyzed using the Schurr model [Allison, S. A., and Schutt, J. M. (1979) Chem. Phys. 41, 35-44] in the infinite polymer length approximation. Time-resolved fluorescence depolarization was measured using a frequency-doubled mode-locked dye laser and frequency- domain acquisition methods. At very high P/D ratios, the anis...

  16. Torsional Detwinning Domino in Nanotwinned One-Dimensional Nanostructures.

    Science.gov (United States)

    Zhou, Haofei; Li, Xiaoyan; Wang, Ying; Liu, Zishun; Yang, Wei; Gao, Huajian

    2015-09-09

    How to maintain sustained deformation in one-dimensional nanostructures without localized failure is an important question for many applications of nanotechnology. Here we report a phenomenon of torsional detwinning domino that leads to giant rotational deformation without localized failure in nanotwinned one-dimensional metallic nanostructures. This mechanism is demonstrated in nanotwinned Cu nanorods via molecular dynamics simulations, where coherent twin boundaries are transformed into twist boundaries and then dissolved one by one, resulting in practically unlimited rotational deformation. This finding represents a fundamental advance in our understanding of deformation mechanisms in one-dimensional metallic nanostructures.

  17. A Torsion-Balance Search for Axion-Like Particles

    Science.gov (United States)

    Fleischer, Frank; Hoedl, Seth; Adelberger, Eric; Heckel, Blayne; Hoyle, C. D.; Shook, David; Swanson, Erik

    2012-03-01

    Axion-like particles can mediate macroscopic parity and time-reversal symmetry violating forces. We will present a search for such a force between polarized electrons and unpolarized atoms using a novel torsion pendulum operating in the unshielded magnetic field of an electromagnet. Laboratory bounds on this force were improved by more than 10 orders of magnitude for pseudoscalars heavier than 1,, and constraints on this force were established over a broad range of astrophysically interesting masses from 10,eV to 10,. Plans for a next generation of this experiment will be discussed.

  18. The group of homomorphisms of abelian torsion groups

    Directory of Open Access Journals (Sweden)

    M. W. Legg

    1979-01-01

    Full Text Available Let G and A be abelian torsion groups. In[5], R. S. Pierce develops a complete set of invariants for Hom(G, A. To compute these invariants he introduces, and uses extensively, the group of small homomorphisms of G into A. Also, using some of Pierce's methods, Fuchs characterizes this group in [1]. Our purpose in this paper is to characterize Hom(G, A in what seems to be a more natural manner than either of the treatments just mentioned.

  19. Photoelectronic vibrometer with polarized light. [for torsional vibration measurements

    Science.gov (United States)

    Kremmer, I.

    1974-01-01

    A seismic torsiometer is described which is based on the reception by a photosensitive transducer of a light flux modulated by a relative rotation of the optical axes of two polaroids. The torsional vibrations of the polaroid fixed to the shaft are transmitted to the other polaroid (which at the same time is the seismic mass of the apparatus) by means of elastic lamellas. The device can work as accelerometer, vibrometer or frequency meter, depending on the value of the ratio between the proper oscillation frequency of the seismic system and the measured vibration frequency.

  20. Dislocations and torsion in graphene and related systems

    Energy Technology Data Exchange (ETDEWEB)

    Juan, Fernando de [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Cortijo, Alberto [Department of Physics, Lancaster University, Lancaster, LA1 4YB (United Kingdom); Vozmediano, Maria A.H., E-mail: vozmediano@icmm.csic.e [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain)

    2010-04-01

    A continuum model to study the influence of dislocations on the electronic properties of condensed matter systems is described and analyzed. The model is based on a geometrical formalism that associates a density of dislocations with the torsion tensor and uses the technique of quantum field theory in curved space. When applied to two-dimensional systems with Dirac points like graphene we find that dislocations couple in the form of vector gauge fields similar to these arising from curvature or elastic strain. We also describe the ways to couple dislocations to normal metals with a Fermi surface.

  1. Isotropic Stars in Higher-Order Torsion Scalar Theories

    Directory of Open Access Journals (Sweden)

    Gamal G. L. Nashed

    2016-01-01

    Full Text Available Two different nondiagonal tetrad spaces reproducing spherically symmetric spacetime are applied to the field equations of higher-order torsion scalar theories. Assuming the existence of conformal Killing vector, two isotropic solutions are derived. We show that the first solution is not stable while the second one confirms a stable behavior. We also discuss the construction of the stellar model and show that one of our solutions is capable of such construction while the other is not. Finally, we discuss the generalized Tolman-Oppenheimer-Volkoff and show that one of our models has a tendency to equilibrium.

  2. Isotropic stars in higher-order torsion scalar theories

    CERN Document Server

    Nashed, Gamal G L

    2016-01-01

    Two tetrad spaces reproducing spherically symmetric spacetime are applied to the equations of motion of higher-order torsion theories. Assuming the existence of conformal Killing vector, two isotropic solutions are derived. We show that the first solution is not stable while the second one confirms a stable behavior. We also discuss the construction of the stellar model and show that one of our solution capable of such construction while the other cannot. Finally, we discuss the generalized Tolman-Oppenheimer-Volkoff and show that one of our models has a tendency to equilibrium.

  3. Slip measurement in a frictional connection by torsional LDV

    Science.gov (United States)

    Schäfer, Günter; Lohrengel, Armin; Hilgermann, Jan Lukas

    2016-06-01

    Frictional shaft-hub connections are often used in drive train applications. The classic version is fitted by a temperature difference between the cold shaft und the hot hub, or simply axial press-fitted at room temperature. The critical point in this type of connection is the contact pressure at the edge of the hub regarding the relative deformation between the shaft and the hub under dynamic operating loads. Another innovative version, the internal press-fit, leads to a tolerance insensitive lightweight design using a tube as shaft and a controlled plastic deformation by internal high pressure. The internal press-fit connection is a special research topic at the IMW, TU Clausthal. The use of internal high pressure allows to trigger the contact pressure at the edge of the hub on an optimum value. The product of contact pressure and slipway is the key value to determine the fatigue resistance and load capacity of this kind of connection. /1/ and /2/ defined a critical range of slipway amplitudes between 5 and 25 µm for fretting. The normal use and main function of a shaft-hub connection is the transmission of torque. Regarding the different torsional stiffness of the shaft and the hub, there will be a difference in deformation in the contact zone between the shaft and the hub, which is necessary to measure on a probe under oscillating torque load. The measurement on the test-rig in /3/ was done with a POLYTEC torsional LDV (controller OFV-4000, sensor head OFV-400). In general the continuously oscillating torque load allowed a serial measurement of the torsional movement of the shaft and the hub. The difference of the two maximum values is the expected slipway between the two parts in the critical zone at the edge of the hub. The main benefits of the Torsional LDV in this application are the very small measuring point (next to the contact), no influence on the probe, no special preparation of the probe and a really good resolution. The paper gives an overview to

  4. Torsion-free generalized connections and Heterotic Supergravity

    CERN Document Server

    Garcia-Fernandez, Mario

    2013-01-01

    This work revisits the notions of connection and curvature in generalized geometry, with emphasis on torsion-free generalized connections on a transitive Courant algebroid, compatible with a generalized metric. Non-exact Courant algebroids have been considered recently by R. Rubio in the context of $B_n$-generalised geometry and arise naturally from the theory of generalized reduction of Burzstyn, Cavalcanti and Gualtieri. As an application, we provide a mathematical derivation of the equations of motion of heterotic supergravity, inspired by the work of Coimbra, Strickland-Constable and Waldram.

  5. Sclerosing Stromal Tumor of the Ovary with Torsion. MRI features

    Energy Technology Data Exchange (ETDEWEB)

    Yerli, H.; Agildere, A. M.; Karadeli, E. [Baskent Univ. School of Medicine, Ankara (Turkey). Dept. of Radiology; Bilezikci, B. [Baskent Univ. School of Medicine, Ankara (Turkey). Dept. of Pathology

    2003-11-01

    Sclerosing stromal tumors are rare benign ovarian neoplasms that are usually diagnosed in the second or third decade of life. Most patients with these tumors present with menstrual irregularities and pelvic pain. We present the magnetic resonance imaging (MRI) findings of a left ovarian sclerosing stromal tumor with torsion that was located in the right parauterine area, and discuss the differential diagnosis for this entity based on MRI findings. In this case, MRI demonstrated a well-defined, predominantly solid mass with a pseudolobular pattern, and showed a shift of the uterus to the left. The surgical and histopathologic aspects of the case are also described.

  6. VERIFICATION OF TORSIONAL OSCILLATING MECHANICAL SYSTEM DYNAMIC CALCULATION RESULTS

    Directory of Open Access Journals (Sweden)

    Peter KAŠŠAY

    2014-09-01

    Full Text Available On our department we deal with optimization and tuning of torsional oscillating mechanical systems. When solving these problems we often use results of dynamic calculation. The goal of this article is to compare values obtained by computation and experimentally. For this purpose, a mechanical system built in our laboratory was used. At first, classical HARDY type flexible coupling has been applied into the system, then we used a pneumatic flexible shaft coupling developed by us. The main difference of these couplings over conventional flexible couplings is that they can change their dynamic properties during operation, by changing the pressure of the gaseous medium in their flexible elements.

  7. On the addition of torsion to chiral gravity

    CERN Document Server

    Santamaria, Ricardo Couso; Garbarz, Alan; Giribet, Gaston

    2011-01-01

    Three-dimensional gravity in Anti-de Sitter space is considered, including torsion. The derivation of the central charges of the algebra that generates the asymptotic isometry group of the theory is reviewed, and a special point of the theory, at which one of the central charges vanishes, is compared with the chiral point of topologically massive gravity. This special point corresponds to a singular point in Chern-Simons theory, where one of the two coupling constants of the SL(2,R) actions vanishes. A prescription to approach this point in the space of parameters is discussed, and the canonical structure of the theory is analyzed.

  8. Dynamical angled brane

    Science.gov (United States)

    Maeda, Kei-ichi; Uzawa, Kunihito

    2016-12-01

    We discuss the dynamical D p -brane solutions describing any number of D p branes whose relative orientations are given by certain SU(2) rotations. These are the generalization of the static angled D p -brane solutions. We study the collision of the dynamical D3 brane with angles in type-II string theory, and show that the particular orientation of the smeared D3-brane configuration can provide an example of colliding branes if they have the same charges. Otherwise a singularity appears before D3 branes collide.

  9. Gait deviations and compensations in pediatric patients with increased femoral torsion.

    Science.gov (United States)

    Bruderer-Hofstetter, Marina; Fenner, Verena; Payne, Erika; Zdenek, Katja; Klima, Harry; Wegener, Regina

    2015-02-01

    Coxa antetorta describes an abnormal torsion of the femur. It is commonly considered a cosmetic problem and is treated surgically only in severe cases and the presence of physical complaints. The purpose of this study was to identify deviations in gait kinematics and kinetics in pediatric patients caused by coxa antetorta and to categorize these deviations into primary and secondary deviations. We conducted a retrospective, cross-sectional three-dimensional (3D) gait analysis study to detect gait deviations in adolescents (n = 18; age range 10.5-17.5 years) with coxa antetorta compared to age-matched healthy control subjects (n = 17). Principal component (PC) analysis was used for data reduction. Linear mixed models applied to PC-scores were used to estimate the main effects within retained PCs followed by a post-hoc subgroup analysis. Patients walked with smaller external foot progression angle, greater knee adduction, more internally rotated and flexed hips and greater anterior pelvic tilt. Subgroup analysis revealed that-depending on knee alignment-patients had higher knee and hip adduction moments. These deviations in joint kinematics and kinetics may be associated with physical complaints and accelerated development of osteoarthritis. Assessment of gait deviations related to coxa antetorta using 3D gait analysis may be an additional tool in individual clinical decision-making.

  10. A torsional MRE joint for a C-shaped robotic leg

    Science.gov (United States)

    Christie, M. D.; Sun, S. S.; Ning, D. H.; Du, H.; Zhang, S. W.; Li, W. H.

    2017-01-01

    Serving to improve stability and energy efficiency during locomotion, in nature, animals modulate their leg stiffness to adapt to their terrain. Now incorporated into many locomotive robot designs, such compliance control can enable disturbance rejection and improved transition between changing ground conditions. This paper presents a novel design of a variable stiffness leg utilizing a magnetorheological elastomer joint in a literal rolling spring loaded inverted pendulum (R-SLIP) morphology. Through the semi-active control of this hybrid permanent-magnet and coil design, variable stiffness is realized, offering a design which is capable of both softening and stiffening in an adaptive sort of way, with a maximum stiffness change of 48.0%. Experimental characterization first serves to assess the stiffness variation capacity of the torsional joint, and through later comparison with force testing of the leg, the linear stiffness is characterized with the R-SLIP-like behavior of the leg being demonstrated. Through the force relationships applied, a generalized relationship for determining linear stiffness based on joint rotation angle is also proposed, further aiding experimental validation.

  11. The quadriceps angle

    DEFF Research Database (Denmark)

    Miles, James Edward; Frederiksen, Jane V.; Jensen, Bente Rona

    2012-01-01

    : Pelvic limbs from red foxes (Vulpes vulpes). METHODS: Q angles were measured on hip dysplasia (HD) and whole limb (WL) view radiographs of each limb between the acetabular rim, mid-point (Q1: patellar center, Q2: femoral trochlea), and tibial tuberosity. Errors of 0.5-2.0 mm at measurement landmarks...

  12. Effect of cyclic torsional preloading on cyclic fatigue resistance of ProTaper Next and Mtwo nickel–titanium instruments

    Directory of Open Access Journals (Sweden)

    Eugenio Pedullà

    2015-06-01

    Conclusions: Torsional preloads reduced the cyclic fatigue resistance of M-wire and conventional (as ProTaper Next and Mtwo NiTi rotary instruments except for Mtwo with 25% or 50% of torsional preloading.

  13. Distinguishing testicular torsion from torsion of the appendix testis by clinical features and signs in patients with acute scrotum

    Directory of Open Access Journals (Sweden)

    Fujita N

    2017-08-01

    Full Text Available Naoyuki Fujita,1 Mitsuhiro Tambo,1 Takatsugu Okegawa,1 Eiji Higashihara,2 Kikuo Nutahara1 1Department of Urology, 2Department of Autosomal Dominant Polycystic Kidney Disease (ADPKD Research, Kyorin University School of Medicine, Mitaka, Tokyo Purpose: Many physicians encounter confusion and difficulty in distinguishing testicular torsion (TT from torsion of the appendix testis (TAT in patients with acute scrotum because of the overlapping signs and symptoms. The objective of our study was to evaluate the clinical features and signs that can help distinguish TT from TAT. Patients and methods: We performed a retrospective study of patients with surgically confirmed TT and TAT at our institute from January 1990 to December 2013. Clinical findings, physical examination findings, climatic conditions, laboratory data, and color Doppler ultrasound (CDUS findings were compared between the TT and TAT groups. Results: Seventy patients were included in this study (49 with TT and 21 with TAT. Patients with TT were significantly older than those with TAT (p < 0.001. The ambient temperature at onset was significantly lower in patients with TT than in patients with TAT (p = 0.038. Testicular swelling, high-riding testes, onset during sleep, high leukocyte counts, and high creatine phosphokinase levels were significantly more common in patients with TT than with TAT (p = 0.021, 0.032, 0.006, 0.003, and 0.043, respectively. Multivariate analysis showed that age and onset during sleep were significant independent factors for detection of TT. Eight patients (16.3% underwent preoperative CDUS evaluation, and an absent or decreased blood signal in the involved testes was significantly correlated with the presence of TT (p = 0.018. Conclusion: In clinical features, age and onset during sleep might be helpful to distinguish TT from TAT. When supported by findings, urgent surgical exploration is warranted in patients with suspected TT based on symptoms and CDUS

  14. An analytical method for calculating torsional constants for arbitrary complicated thin-walled cross-sections

    Institute of Scientific and Technical Information of China (English)

    DU Baisong; GE Yaojun; ZHOU Zheng

    2007-01-01

    In this paper,an analytical method is proposed for calculating torsional constants for complicated thin-walled cross-sections with arbitrary closed or open rib stiffeners.This method uses the free torsional theory and the principle of virtual work to build goveming equilibrium equations involving unknown shear flows and twisting rate.After changing the form of the equations and combining these two unknowns into one,torsional function,which is a function of shear flow,shear modulus,and twisting rate,is included in the governing equations as only one of the unknowns.All the torsional functions can be easily obtained from these homogeneous linear equations,and torsional constants can be easily obtained from the torsional functions.The advantage of this method is that we can easily and directly obtain torsional constants from the torsional functions,rather than the more sophisticated shear flow and twisting rate calculations.Finally,a complicated thin-walled cross-section is given as a valid numerical example to verify the analytical method,which is much more accurate and simpler than the traditional finite element method.

  15. A torsional completion of gravity for Dirac matter fields and its applications to neutrino oscillations

    Science.gov (United States)

    Fabbri, Luca; Vignolo, Stefano

    2016-01-01

    In this paper, we consider the torsional completion of gravitation for an underlying background filled with Dirac fields, applying it to the problem of neutrino oscillations: we discuss the effects of the induced torsional interactions as corrections to the neutrino oscillations mechanism.

  16. Numerical Analysis on Variation of Dynamic Response of Girder Bridges with Torsional Reinforcement Panels

    Directory of Open Access Journals (Sweden)

    Kang Jae-Yoon

    2015-01-01

    Full Text Available The dynamic flexural behaviour of the railway bridge is influenced by its torsional behaviour. Especially, in the case of girder railway bridges, the dynamic response tends to amplify when the natural frequency in flexure (1st vibration mode is close to that in torsion (2nd vibration mode. In order to prevent such situation, it is necessary to adopt a flexural-to-torsional natural frequency ratio larger than 120%. This study proposes a solution shifting the natural frequency in torsion to high frequency range and restraining torsion by installing concrete panels on the bottom flange of the girder so as to prevent the superposition of the responses in the girder bridge. The applicability of this solution is examined by finite element analysis of the shift of the torsional natural frequency and change in the dynamic response according to the installation of the concrete panels. The analytical results for a 30 m-span girder railway bridge indicate that installing the concrete panels increases the natural frequency in torsion by restraining the torsional behaviour and reduces also the overall dynamic response. It is seen that the installation of 100 mm-thick concrete panels along a section of 4 m at both extremities of the girder can reduce the dynamic response by more than 30%.

  17. Static and dynamic tensile behaviour of aluminium processed by high pressure torsion

    NARCIS (Netherlands)

    Verleysen, P.; Oelbrandt, W.; Naghdy, S.; Kestens, L.

    2015-01-01

    High pressure torsion (HPT) is a severe plastic deformation technique in which a small, disk-like sample is subjected to a torsional deformation under a high hydrostatic pressure. In present study, the static and dynamic tensile behaviour of commercially pure aluminium (99.6 wt%) processed by HPT is

  18. Protective effect of sildenafil citrate on contralateral testis injury after unilateral testicular torsion/detorsion

    Directory of Open Access Journals (Sweden)

    Hamit Yíldíz

    2011-01-01

    Full Text Available OBJECTIVES: This study was designed to investigate prevention of contralateral testicular injury with sildenafil citrate after unilateral testicular torsion/detorsion. METHODS: Thirty-seven adult male rats were divided into four groups: sham operated (group 1, n = 7, torsion/detorsion + saline (group 2, n = 10, torsion/detorsion + 0.7 mg of sildenafil citrate (group 3, n = 10 and torsion/detorsion + 1.4 mg of sildenafil citrate (group 4, n = 10. Unilateral testicular torsion was created by rotating the right testis 720º in a clockwise direction for 2 h in other groups, except for group 1, which was served as sham group. After torsion (2 h and detorsion (2 h periods, rats were killed. RESULTS: The level of reduced glutathion (GSH (p0.05. Histopathological changes were detected in groups 2, 3 and 4. CONCLUSION: These results suggest that biochemically and histologically torsion/detorsion injury occurs in the contralateral testis following 2-h torsion and 2-h detorsion and that administration of low-dose sildenafil citrate before detorsion prevents ischemia/reperfusion cellular damage in testicular tissue.

  19. A discussion on the most general torsion-gravity with electrodynamics for Dirac spinor matter fields

    CERN Document Server

    Fabbri, Luca

    2014-01-01

    We consider the most general torsional completion of gravity and electrodynamics with Dirac spinorial matter fields, showing that continuity and consistency constrain torsion to be completely antisymmetric and the model to be parity-invariant and described by either the least-order derivative model or the renormalizable model.

  20. One-stage correction of chordee and 180-degree penile torsion.

    Science.gov (United States)

    Redman, J F; Bissada, N K

    1976-06-01

    The surgical management of a patient with 180-degree penile torsion, balanitic hypospadias, and chordee is presented. Complete resolution of the torsion was effected by completely reflecting the penile skin. Correction of the penile curvature was accomplished simultaneously by freeing the corpora spongiosa from the corpora cavernosa.

  1. Faraday Rotation and Primordial Magnetic Fields Constraints on Ultraviolet Lorentz Violation with Spacetime Torsion

    Science.gov (United States)

    de Andrade, L. C. Garcia

    Recently Kahniashvili et al.9 presented a unified treatment for ultraviolet Lorentz violation (LV) testing through electromagnetic wave propagation in magnetized plasmas, based on dispersion and rotation measured data. Based on the fact discovered recently by Kostelecky et al., 3 that LV may place constraints on spacetime torsion, in this paper it is shown that on the limit of very low frequency torsion waves, it is possible to constraint torsion from Faraday rotation and CMB on a similar fashion as Minkowski spacetime plus torsion. Here, the Maxwells modified equations are obtained by a perturbative method introduced by de Sabbata and Gasperini [Introduction to Gravitation (World Scientific, 1980)]. Torsion is constraint to QCMB≈10-18 GeV which is not so stringent as the 10-31 GeV obtained by Kostelecky et al. However, Gamma-Ray Bursts (GRBs) may lead to the more string value obtained by Kostelecky et al.Another interesting constraint on torsion is shown to be placed by galactic dynamo seed magnetic fields. For torsion effects be compatible with the galactic dynamo seeds, one obtains a torsion constraint of 10-33 GeV which is two orders of magnitude more stringent that the above Kostelecky et al. limit.

  2. Nonspecificity of the rim sign in the scintigraphic diagnosis of missed testicular torsion

    Energy Technology Data Exchange (ETDEWEB)

    Vieras, F.; Kuhn, C.R.

    1983-02-01

    Causes of a hyperemic peritesticular rim on dynamic and static scintigrams are reviewed. Of 6 patients exhibiting such a pattern, 3 had missed testicular torsion; the other 3 had tumor, trauma, or inflamation. The authors conclude that a hyperemic peritesticular rim is a nonspecific finding reflecting underlying pathophysiological changes and is not pathognomonic of missed torsion.

  3. Nonspecificity of the rim sign in the scintigraphic diagnosis of missed testicular torsion

    Energy Technology Data Exchange (ETDEWEB)

    Vieras, F.; Kuhn, C.R.

    1983-02-01

    Causes of a hyperemic peritesticular rim on dynamic and static scintigrams are reviewed. Of 6 patients exhibiting such a pattern, 3 had missed testicular torsion; the other 3 had tumor, trauma, or inflammation. The authors conclude that a hyperemic peritesticular rim is a nonspecific finding reflecting underlying pathophysiological changes and is not pathognomonic of missed torsion.

  4. Torsional natural frequency tuning by means of pneumatic flexible shaft couplings

    OpenAIRE

    2015-01-01

    This article deals with the use of pneumatic flexible shaft couplings as device for tuning torsional natural frequencies of mechanical systems. These couplings are using air bellows as flexible elements. Their torsional stiffness can be changed by air pressure change, the natural frequencies of whole mechanical system may be adjusted on desired value.

  5. Torsional natural frequency tuning by means of pneumatic flexible shaft couplings

    Directory of Open Access Journals (Sweden)

    Peter KAŠŠAY

    2015-12-01

    Full Text Available This article deals with the use of pneumatic flexible shaft couplings as device for tuning torsional natural frequencies of mechanical systems. These couplings are using air bellows as flexible elements. Their torsional stiffness can be changed by air pressure change, the natural frequencies of whole mechanical system may be adjusted on desired value.

  6. Characteristics of Pneumatic Tuners of Torsional Oscillation as a Result of Patent Activity

    Directory of Open Access Journals (Sweden)

    Homišin Jaroslav

    2016-12-01

    Full Text Available Mechanical systems with combustion engines, compressors, pumps and fans, can be characterized as torsional oscillating mechanical systems (TOMS. It is therefore necessary to control their dangerous torsional vibrations. It was confirmed that dangerous torsional vibration can be reduced to acceptable level by an appropriate adjustment, respectively by tuning the TOMS. According to several authors, the most appropriate way of system tuning is application of suitable flexible element, which is flexible shaft coupling. It turned out that one of the types of shaft couplings, which are particularly suited to meeting this objective are pneumatic flexible shaft couplings, to act as so-called pneumatic tuners of torsional oscillations. The issue of research and development of pneumatic tuners of torsional oscillations, among other things is, long-term in the focus of the author. The existence of tuners creates the opportunity to develop new ways of tuning torsional oscillating mechanical systems. The author of the scientific article will focus on the characteristics of developed pneumatic tuners of torsional oscillation in terms of their design, construction, function, significance advantages and conditions imposed on pneumatic tuners based on the results of his patent activity. Simultaneously provides information about the characteristic properties of pneumatic tuners of torsional oscillations in the general design.

  7. Torsional Ultrasound Sensor Optimization for Soft Tissue Characterization

    Directory of Open Access Journals (Sweden)

    Juan Melchor

    2017-06-01

    Full Text Available Torsion mechanical waves have the capability to characterize shear stiffness moduli of soft tissue. Under this hypothesis, a computational methodology is proposed to design and optimize a piezoelectrics-based transmitter and receiver to generate and measure the response of torsional ultrasonic waves. The procedure employed is divided into two steps: (i a finite element method (FEM is developed to obtain a transmitted and received waveform as well as a resonance frequency of a previous geometry validated with a semi-analytical simplified model and (ii a probabilistic optimality criteria of the design based on inverse problem from the estimation of robust probability of detection (RPOD to maximize the detection of the pathology defined in terms of changes of shear stiffness. This study collects different options of design in two separated models, in transmission and contact, respectively. The main contribution of this work describes a framework to establish such as forward, inverse and optimization procedures to choose a set of appropriate parameters of a transducer. This methodological framework may be generalizable for other different applications.

  8. Isolated fallopian tube torsion: sonographic and CT features

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, Jenna C.; Binkovitz, Larry A.; Binkovitz, Leah E. [Columbus Children' s Hospital, Department of Radiology, Columbus, OH (United States)

    2008-02-15

    Isolated fallopian tube torsion (IFTT) rarely occurs in pediatric patients and is difficult to diagnose preoperatively. To determine the common sonographic and CT findings in girls with IFTT. We retrospectively reviewed the hospital charts and imaging studies of the eight girls diagnosed with and treated for IFTT at Columbus Children's Hospital between January 1995 and June 2006 whose final diagnosis was IFTT. The mean age was 13 years with a range of 12 to 15 years. Two girls were premenarcheal. The most common presenting symptom was acute pelvic pain (n = 5). All patients were imaged. Six girls were imaged first with US, and the most common finding was a complex cystic pelvic mass in the midline (n = 5) and normal uterus and ovaries. Three of the eight girls had imaging with CT. In two girls, the torsed tube could be identified. In 63% of the girls, the uterus was deviated toward the side of torsion. The correct preoperative diagnosis was made in only one girl. None of the torsed fallopian tubes was salvaged at surgery. Pathological findings included ipsilateral adnexal cysts associated with the torsed tube (n = 7). IFTT should be considered in the differential diagnosis for perimenarcheal girls who present with acute pelvic pain and who demonstrate a cystic mass in a midline position (either in the cul-de-sac or superior to the uterus) associated with a normal ipsilateral ovary. (orig.)

  9. The CFT dual of AdS gravity with torsion

    CERN Document Server

    Klemm, Dietmar

    2007-01-01

    We consider the Mielke-Baekler model of three-dimensional AdS gravity with torsion, which has gravitational and translational Chern-Simons terms in addition to the usual Einstein-Hilbert action with cosmological constant. It is shown that the topological nature of the model leads to a finite Fefferman-Graham expansion. We derive the holographic stress tensor and the associated Ward identities and show that, due to the asymmetry of the left- and right-moving central charges, a Lorentz anomaly appears in the dual conformal field theory. Both the consistent and the covariant Weyl and Lorentz anomaly are determined, and the Wess-Zumino consistency conditions for the former are verified. Moreover we consider the most general solution with flat boundary geometry, which describes left-and right-moving gravitational waves on AdS_3 with torsion, and shew that in this case the holographic energy-momentum tensor is given by the wave profiles. The anomalous transformation laws of the wave profiles under diffeomorphisms p...

  10. Torsion of Meckel’s Diverticulum in a Child

    Directory of Open Access Journals (Sweden)

    Satoko Nose

    2013-01-01

    Full Text Available Meckel’s diverticulum (MD is a common congenital anomaly of the gastrointestinal tract, the majority of cases of which are clinically silent. Patients with asymptomatic MD can unexpectedly develop acute abdominal pain. Making a diagnosis of MD is often difficult due to the lack of specific symptoms caused by this condition. Diagnostic laparotomy can be useful for making an accurate and prompt diagnosis of complicated MD. We herein describe a pediatric case of torsion of a MD in whom we performed laparoscopic-assisted emergency surgery. The patient was an 11-year-old male who developed sudden severe right lower abdominal pain. Clinical and laboratory findings were suggestive of appendicitis, however computed tomography scans showed a large cystic mass in the pelvis. Exploratory laparoscopy led to a diagnosis of torsion of a MD, and wedge resection of the gangrenous MD was performed through an umbilical port incision. The patient’s postoperative course was uneventful. We conclude that diagnostic laparoscopy followed by laparoscopy-assisted Meckel’s diverticulectomy via an umbilical incision is useful in the treatment of acute abdomen caused by MD.

  11. Acute gallbladder torsion - a continued pre-operative diagnostic dilemma

    Directory of Open Access Journals (Sweden)

    Desrochers Randal

    2011-04-01

    Full Text Available Abstract Acute gallbladder volvulus continues to remain a relatively uncommon process, manifesting itself usually during exploration for an acute surgical abdomen with a presumptive diagnosis of acute cholecystitis. The pathophysiology is that of mechanical organo-axial torsion along the gallbladder's longitudinal axis involving the cystic duct and cystic artery, and with a pre-requisite of local mesenteric redundancy. The demographic tendency is septua- and octo-genarians of the female sex, and its overall incidence is increasing, this being attributed to increasing life expectancy. We discuss two cases of elderly, fragile women presenting to the emergency department complaining of sudden onset right upper quadrant abdominal pain. Their subsequent evaluation suggested acute cholecystitis. Ultimately both were taken to the operating room where the correct diagnosis of gallbladder torsion was made. Pre-operative diagnosis continues to be a major challenge with only 4 cases reported in the literature diagnosed with pre-operative imaging; the remainder were found intra-operatively. Consequently, a delay in diagnosis can have devastating patient outcomes. Herein we propose a necessary high index of suspicion for gallbladder volvulus in the outlined patient demographic with symptoms and signs mimicking acute cholecystitis.

  12. A review of main controversial aspects of acute testicular torsion

    Institute of Scientific and Technical Information of China (English)

    ´Ad ´am Mikl ´os Feh ´er; Zolt ´an Bajory

    2016-01-01

    Testicular torsion (TT) is a severe acute urological emergency caused by twisting of the spermatic cord. It requires prompt diagnosis and treatment. Unfortunately, its importance is still underestimated in everyday life: early-detected TT can be cured in almost every case, whereas late identification may lead to loss of the testicles. We present a compre-hensive review of TT, including the aetiology, risk factors, diagnosis, treatment and outcome, based on recently published articles. The novel and the major controversial aspects of this topic are highlighted. The PubMed and ScienceDirect databases were searched with the following keywords: TT, torsion of the spermatic cord and acute scrotum, particular stress being placed on articles published in the last 5 years. The ge-netic aspects of TT are discussed, together with the diagnostic possibilities, such as so-nography, radionuclide and fluorescent imaging techniques. The effective surgical techniques and potential drugs for reducing molecular injuries were surveyed. Finally, the major controversial aspects of TT are considered. The new concepts of TT demonstrate that certain features remain unclear. New, more accurate diagnostic tools and prompt management may contribute to a better prognosis and prevent the loss of the testicles.

  13. Solar neutrinos, helicity effects and new affine gravity with torsion

    CERN Document Server

    Cirilo-Lombardo, Diego Julio

    2013-01-01

    New f(R,T) model of gravitation, introduced previously by the author, is considered. It is based on an affine geometrical construction in which the torsion is a dynamical field, the coupling is minimal and the theory is Lorentz invariant by construction. It was shown that the Dirac equation emerges from the same space time and acquires a modification (coupling-like) of the form {\\gamma}^{{\\alpha}}j((1-d)/d){\\gamma}h_{{\\alpha}}, with h_{{\\alpha}} the torsion axial vector, j a parameter of pure geometrical nature and d, the spacetime dimension. In the present work it is shown that this interaction produces a mechanism of spin (helicity) flipping, with its consequent weak symmetry violation. The cross section of this process is explicitly calculated and a logaritmical energy dependence (even at high energies) is found. This behavior is reminiscent of similar computations made by Hans Bethe in the context of neutrino astrophysics. These results are applied to the solar neutrino case and compared with similar resu...

  14. Test particle acceleration in torsional spine magnetic reconnection

    Science.gov (United States)

    Hosseinpour, M.

    2014-10-01

    Three-dimensional (3D) magnetic reconnection is taking place commonly in astrophysical and space plasmas, especially in solar flares which are rich sources of highly energetic particles. One of the proposed mechanisms for steady-state 3D magnetic reconnection is "torsional spine reconnection". By using the magnetic and electric fields for "torsional spine reconnection", we numerically investigate the features of test particle acceleration with input parameters for the solar corona. We show that efficient acceleration of a relativistic proton is possible near the null point where it can gain up to 100 MeV of kinetic energy within a few milliseconds. However, varying the injection position results in different scenarios for proton acceleration. A proton is most efficiently accelerated when it is injected at the point where the magnetic field lines change their curvature in the fan plane. Moreover, a proton injected far away from the null point cannot be accelerated and, even in some cases, it is trapped in the magnetic field. In addition, adopting either spatially uniform or non-uniform localized plasma resistivity does not much influence the features of trajectory.

  15. Torsional Oscillations in Automotive Transmissions: Experimental Analysis and Modelling

    Directory of Open Access Journals (Sweden)

    Enrico Galvagno

    2016-01-01

    Full Text Available The paper investigates the torsional oscillations of an automotive transmission system by means of an experimental test bench used to validate the proposed lumped parameter model. The rig consists of a Dual Clutch Transmission (DCT and a Manual Transmission (MT connected through the respective output shafts, while the excitation is provided by two electric motors, which are controlled in speed or torque. The experimental analysis includes the measurement of the external torques, applied by the two electric motors to the mechanical system, and the measurement of the system response in terms of angular speeds at different positions along the transmission line. The frequency response of the system is estimated from the experimental data and compared with the results of a 5-degree-of-freedom lumped parameter model, which proves to be adequate to describe the dynamic behaviour of the system up to a frequency of 200 Hz. The comparison between simulated results and experimental data shows good agreement, so the model can be used to predict the torsional vibrations of the transmission system in the linear field. Moreover, the effects of the nonlinearities associated with the mean value of the excitations are shown. Finally the influence of the selected gear ratio on the experimental frequency response is discussed.

  16. Giant Meckel’s diverticulum torsion that mimics adnexal pathology

    Directory of Open Access Journals (Sweden)

    Serdar Kirmizi

    2016-01-01

    Full Text Available Meckel’s diverticulum is a real diverticulum located at the antimesenteric portion of intestinal loops and including all layers of the intestinal wall. It is the most common congenital anomaly of the gastrointestinal tract, and its incidence is 1–3%. Many asymptomatic cases are diagnosed when complications occur. A 23-year-old female patient applied to gynaecology emergency clinic with pelvic pain complaint. Laparotomy was performed with the diagnosis of acute abdomen because the physical examination and imaging studies did not exclude tuboovary pathology. Giant Meckel’s diverticulitis and ischemic bowel loops that had been torsion were observed. Obstruction is the most common complication and generally originates from inflammation, adhesions, intussusception and omphalo-mesenteric band. In this case, it was seen that mobilized diverticulitis can be complicated without any fibrous band or adhesion to adjacent organs. This case supports that there can be torsion of bowel in free Meckel’s diverticulum. Meckel’s diverticulum settled in the pelvic region can make a clinical manifestation that is difficult to distinguish from adnexal diseases. It should be kept in mind for cases that start with pelvic pain, form adnexal pathology suspicion and cause an acute abdomen.

  17. A strain gradient plasticity theory with application to wire torsion

    KAUST Repository

    Liu, J. X.

    2014-06-05

    Based on the framework of the existing strain gradient plasticity theories, we have examined three kinds of relations for the plastic strain dependence of the material intrinsic length scale, and thus developed updated strain gradient plasticity versions with deformation-dependent characteristic length scales. Wire torsion test is taken as an example to assess existing and newly built constitutive equations. For torsion tests, with increasing plastic strain, a constant intrinsic length predicts too high a torque, while a decreasing intrinsic length scale can produce better predictions instead of the increasing one, different from some published observations. If the Taylor dislocation rule is written in the Nix-Gao form, the derived constitutive equations become singular when the hardening exponent gets close to zero, which seems questionable and calls for further experimental clarifications on the exact coupling of hardening due to statistically stored dislocations and geometrically necessary dislocations. Particularly, when comparing the present model with the mechanism-based strain gradient plasticity, the present model satisfies the reciprocity relation naturally and gives different predictions even under the same parameter setting. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  18. Topology of magnetic helicity of torsioned filaments in Hall plasmas

    CERN Document Server

    de Andrade, L C Garcia

    2007-01-01

    A solution of magnetic Hall equations for plasma filaments in the Coulomb gauge is obtained in the non-holonomic frame. Some physical features of the solution include, the non-conservation of the magnetic helicity and the decay of the magnetic field in the filaments. From the mathematical point of view,the presence of Frenet torsion in the filament is actually shown to be fundamental for the breaking of conservation of magnetic helicity in the case of helicoidal filaments. Since the magnetic helicity is not conserved even in the Coulomb gauge, and the magnetic field decays, one can say that the dynamo action fails. Actually the presence of torsion enhances the breaking of magnetic field helicity conservation. A similar formula of the one obtained here without considering the Hall effect has been obtained by Moffatt and Ricca (PRSA-1992) in the case of holonomic filaments. It is shown that unknotted magnetic filaments may place a lower bound on the magnetic energy. Discussions on the writhe number are also dis...

  19. Strengthening of Steel Columns under Load: Torsional-Flexural Buckling

    Directory of Open Access Journals (Sweden)

    Martin Vild

    2016-01-01

    Full Text Available The paper presents experimental and numerical research into the strengthening of steel columns under load using welded plates. So far, the experimental research in this field has been limited mostly to flexural buckling of columns and the preload had low effect on the column load resistance. This paper focuses on the local buckling and torsional-flexural buckling of columns. Three sets of three columns each were tested. Two sets corresponding to the base section (D and strengthened section (E were tested without preloading and were used for comparison. Columns from set (F were first preloaded to the load corresponding to the half of the load resistance of the base section (D. Then the columns were strengthened and after they cooled, they were loaded to failure. The columns strengthened under load (F had similar average resistance as the columns welded without preloading (E, meaning the preload affects even members susceptible to local buckling and torsional-flexural buckling only slightly. This is the same behaviour as of the tested columns from previous research into flexural buckling. The study includes results gained from finite element models of the problem created in ANSYS software. The results obtained from the experiments and numerical simulations were compared.

  20. From Tucking to Twisting; A Case of Self-induced Testicular Torsion in a Cross Dressing Male.

    Science.gov (United States)

    Epps, Thomas; McCormick, Barrett; Ali, Antar; Duboy, Alberto; Gillen, James; Martinez, Daniel; Carrion, Rafael

    2016-07-01

    A self-induced, non-traumatic testicular torsion is a rare entity that to our knowledge has not been reported in the literature. We report the case of a 28-year-old male who caused a self-induced testicular torsion during acts associated with cross dressing. Differential diagnosis of the acute scrotum in an adult should always include testicular torsion, as outcomes in this population are worse than in younger populations. Additional unusual causes of testicular torsion are reviewed.

  1. Analysis on volume invariability of metal circular shaft in torsion deformation

    Science.gov (United States)

    Yang, Li-Hong; Zou, Guang-Ping; He, Yun-Zeng; Wang, Hui

    2010-03-01

    Volume invariability of metal circular shaft in the case of small strain torsion deformation and large strain torsion deformation was, respectively, discussed experimentally and theoretically in this study. In accordance with the elastoplastic theory, it was given that the shear stress did not cause the change of volume in the large strain range. By utilizing torsion experiment with the solid shaft of low carbon steel, it was proved that metal can meet the conditions of the volume invariability in torsion deformation while the cumulative damage was not very serious. Volumetric deformation was analyzed in torsion of circular shaft in the perspective of micromechanics. Finally, Swift effect of solid circular shaft and tubular shaft of brass material were interpreted by using the formulae of elastoplastic critic load obtained from double-limb bar model test presented by Shanley.

  2. Torsion effect of swing frame on the measurement of horizontal two-plane balancing machine

    Science.gov (United States)

    Wang, Qiuxiao; Wang, Dequan; He, Bin; Jiang, Pan; Wu, Zhaofu; Fu, Xiaoyan

    2017-03-01

    In this paper, the vibration model of swing frame of two-plane balancing machine is established to calculate the vibration center position of swing frame first. The torsional stiffness formula of spring plate twisting around the vibration center is then deduced by using superposition principle. Finally, the dynamic balancing experiments prove the irrationality of A-B-C algorithm which ignores the torsion effect, and show that the torsional stiffness deduced by experiments is consistent with the torsional stiffness calculated by theory. The experimental datas show the influence of the torsion effect of swing frame on the separation ratio of sided balancing machines, which reveals the sources of measurement error and assesses the application scope of A-B-C algorithm.

  3. Electron exchange in conformationally restricted donor-spacer-acceptor dyads: angle dependence and involvement of upper-lying excited States.

    Science.gov (United States)

    Benniston, Andrew C; Harriman, Anthony; Li, Peiyi; Patel, Pritesh V; Sams, Craig A

    2008-01-01

    The rate constant for triplet energy transfer (k(TET)) has been measured in fluid solution for a series of mixed-metal Ru-Os bis(2,2':6',2''-terpyridine) complexes built around a tethered biphenyl-based spacer group. The length of the tether controls the central torsion angle for the spacer, which can be varied systematically from 37 to 130 degrees . At low temperature, but still in fluid solution, the spacer adopts the lowest-energy conformation and k(TET) shows a clear correlation with the torsion angle. A similar relationship holds for the inverse quantum yield for emission from the Ru-terpy donor. Triplet energy transfer is more strongly activated at higher temperature and the kinetic data require analysis in terms of two separate processes. The more weakly activated step involves electron exchange from the first-excited triplet state on the Ru-terpy donor and the size of the activation barrier matches well with that calculated from spectroscopic properties. The pre-exponential factor derived for this process correlates remarkably well with the torsion angle and there is a large disparity in electronic coupling through pi and sigma orbitals on the spacer. The more strongly activated step is attributed to electron exchange from an upper-lying triplet state localized on the Ru-terpy donor. Here, the pre-exponential factor is larger but shows the same dependence on the geometry of the spacer. Strangely, the difference in coupling through pi and sigma orbitals is much less pronounced. Despite internal flexibility around the spacer, k(TET) shows a marked dependence on the torsion angle computed for the lowest-energy conformation.

  4. The role of nonlinear torsional contributions on the stability of flexural-torsional oscillations of open-cross section beams

    Science.gov (United States)

    Di Egidio, Angelo; Contento, Alessandro; Vestroni, Fabrizio

    2015-12-01

    An open-cross section thin-walled beam model, already developed by the authors, has been conveniently simplified while maintaining the capacity of accounting for the significant nonlinear warping effects. For a technical range of geometrical and mechanical characteristics of the beam, the response is characterized by the torsional curvature prevailing over the flexural ones. A Galerkin discretization is performed by using a suitable expansion of displacements based on shape functions. The attention is focused on the dynamic response of the beam to a harmonic force, applied at the free end of the cantilever beam. The excitation is directed along the symmetry axis of the beam section. The stability of the one-component oscillations has been investigated using the analytical model, showing the importance of the internal resonances due to the nonlinear warping coupling terms. Comparison with the results provided by a computational finite element model has been performed. The good agreement among the results of the analytical and the computational models confirms the effectiveness of the simplified model of a nonlinear open-cross section thin-walled beam and overall the important role of the warping and of the torsional elongation in the study of the one-component dynamic oscillations and their stability.

  5. Contact angle hysteresis explained.

    Science.gov (United States)

    Gao, Lichao; McCarthy, Thomas J

    2006-07-04

    A view of contact angle hysteresis from the perspectives of the three-phase contact line and of the kinetics of contact line motion is given. Arguments are made that advancing and receding are discrete events that have different activation energies. That hysteresis can be quantified as an activation energy by the changes in interfacial area is argued. That this is an appropriate way of viewing hysteresis is demonstrated with examples.

  6. The lateral angle revisited

    DEFF Research Database (Denmark)

    Morgan, Jeannie; Lynnerup, Niels; Hoppa, R.D.

    2013-01-01

    measurements taken from computed tomography (CT) scans. Previous reports have observed that the lateral angle size in females is significantly larger than in males. The method was applied to an independent series of 77 postmortem CT scans (42 males, 35 females) to validate its accuracy and reliability...... method appears to be of minimal practical use in forensic anthropology and archeology. © 2013 American Academy of Forensic Sciences....

  7. Lorentz violation bounds from torsion trace fermion sector and galaxy M51 data and chiral dynamos

    Energy Technology Data Exchange (ETDEWEB)

    Garcia de Andrade, L.C. [IF-UERJ, Departamento de Fisica Teorica, Rio de Janeiro, RJ (Brazil)

    2017-06-15

    Earlier we have computed a Lorentz violation (LV) bound for torsion terms via galactic dynamos and found bounds similar to the one obtained by Kostelecky et al. (Phys Rev Lett 100:111102, 2008) which is of the order of 10{sup -31} GeV. Their result was found making use of the axial torsion vector in terms of Dirac spinors and minimal torsion coupling in flat space-time of fermions. In this paper, a torsion dynamo equation obtained using the variation of the torsion trace and galaxy M51 data of 500 pc are used to place an upper bound of 10{sup -26} GeV in LV, which agrees with the one by Kostelecky and his group using an astrophysical framework background. Their lowest bound was obtained in earth laboratory using dual masers. One of the purposes of this paper is to apply the Faraday self-induction magnetic equation, recently extended to torsioned space-time, by the author to show that it lends support to physics in Riemann-Cartan space-time, in several distinct physical backgrounds. Backreaction magnetic effects are used to obtain the LV bounds. Previously Bamba et al. (JCAP 10:058, 2012) have used the torsion trace in their teleparallel investigation of the IGMF, with the argument that the torsion trace leads to less weaker effects than the other irreducible components of the torsion tensor. LV is computed in terms of a chiral-torsion-like current in the new dynamo equation analogous to the Dvornikov and Semikoz dynamo equation with chiral magnetic currents. Making use of the chiral-torsion dynamo equation we estimate the LV bounds in the early universe to be of the order of 10{sup -24} GeV, which was the order of the charged-lepton sector. Our main result is that it is possible to obtain more stringent bounds than the ones found in the fermion sector of astrophysics in the new revised 2017 data table for CPT and Lorentz violation by Kostelecky and Mewes. They found in several astrophysical backgrounds, orders of magnitude such as 10{sup -24} and 10{sup -23} Ge

  8. Lorentz violation bounds from torsion trace fermion sector and galaxy M 51 data and chiral dynamos

    Science.gov (United States)

    Garcia de Andrade, L. C.

    2017-06-01

    Earlier we have computed a Lorentz violation (LV) bound for torsion terms via galactic dynamos and found bounds similar to the one obtained by Kostelecky et al. (Phys Rev Lett 100:111102, 2008) which is of the order of 10^{-31} GeV. Their result was found making use of the axial torsion vector in terms of Dirac spinors and minimal torsion coupling in flat space-time of fermions. In this paper, a torsion dynamo equation obtained using the variation of the torsion trace and galaxy M51 data of 500 pc are used to place an upper bound of 10^{-26} GeV in LV, which agrees with the one by Kostelecky and his group using an astrophysical framework background. Their lowest bound was obtained in earth laboratory using dual masers. One of the purposes of this paper is to apply the Faraday self-induction magnetic equation, recently extended to torsioned space-time, by the author to show that it lends support to physics in Riemann-Cartan space-time, in several distinct physical backgrounds. Backreaction magnetic effects are used to obtain the LV bounds. Previously Bamba et al. (JCAP 10:058, 2012) have used the torsion trace in their teleparallel investigation of the IGMF, with the argument that the torsion trace leads to less weaker effects than the other irreducible components of the torsion tensor. LV is computed in terms of a chiral-torsion-like current in the new dynamo equation analogous to the Dvornikov and Semikoz dynamo equation with chiral magnetic currents. Making use of the chiral-torsion dynamo equation we estimate the LV bounds in the early universe to be of the order of 10^{-24} GeV, which was the order of the charged-lepton sector. Our main result is that it is possible to obtain more stringent bounds than the ones found in the fermion sector of astrophysics in the new revised 2017 data table for CPT and Lorentz violation by Kostelecky and Mewes. They found in several astrophysical backgrounds, orders of magnitude such as 10^{-24} and 10^{-23} GeV which are not so

  9. Torsionally Excited Dimethyl Ether in the Laboratory and in Space

    Science.gov (United States)

    Endres, C. P.; Müller, H. S. P.; Lewen, F.; Giesen, T. F.; Schlemmer, S.; Drouin, B. J.; Bisschop, S.; Groner, P.

    2010-06-01

    Dimethyl ether (DME) is highly abundant in hot cores and numerous transitions within the vibrational ground state have been detected in various interstellar line surveys of sources such as Orion KL. As a nearly prolate asymmetric top with two internal rotors, it shows a complex spectrum with low lying torsional modes. The energy levels of the two lowest torsional states (v11, and v15) lie only 200 and 240 cm-1 above the ground state (barrier height ≈ 915 cm-1), and are thus sufficiently populated in these interstellar sources to exhibit transitions in line surveys due to high excitation temperatures in hot cores. So far, the lack of sufficiently accurate predictions for the two lowest excited torsional states prevented their identification in astronomical spectra. Therefore, we analyzed spectra, which have been recorded within the context of the investigations of the ground state. In total, more than 9500 transitions have been assigned covering the frequency range from 38 up to 1670 GHz. The enlarged splitting of each rotational level into four substates (AA, EE, AE, EA) compared to its size in the ground state and a large number of perturbed transitions hampered not only the line assignment but also the astrophysical modelling. However, the inclusion of interaction terms between both excited states in the model of an effective Hamiltonian for a symmetric two-top rotor, allowed us to model both excited states within a global fit, and also to accurately determine the energy difference between both states. Frequency predictions have been calculated based on this analysis and have been used to unambiguously assign numerous rotational transitions within these excited states in the astronomical line survey of the hot core region G327.3-0.6. P. Schilke, T.D. Groesbeck et al., Astrophys.J.Suppl.Ser., 108,(1997) 301-337 P. Schilke, D.J. Benford, T.R. Hunter et al., Astrophys.J.Suppl.Ser., 132,(2001) 281-364. P. Groner, S. Albert, E. Herbst, and F.C. De Lucia, Astrophys

  10. 基于MATLAB的万向联轴器非线性扭振仿真%Simulation of Nonlinear Torsional Vibration of Universal Joint Based on MATLAB

    Institute of Scientific and Technical Information of China (English)

    徐翔; 周瑞平; 汪萌生; 祁亮

    2011-01-01

    利用第一类Lagrange方程建立了万向联轴器非线性扭转振动方程,在此基础上得到该系统的仿真模型并通过特例计算和仿真验证了该模型的正确性;然后通过修改参数获得了系统固有频率随夹角增大而逐渐减小的变化关系,得到了在夹角小于20°时的情况下可忽略夹角进行扭振计算的结论,为万向联轴器在船舶推进轴系的设计和应用提供理论支持.%The nonlinear torsional vibration equations of universal joint is derived by the first kind of Lagrange's equations, and the simulation model of this system is obtained, which was proved to be correct through calculation and simulation results in a special case, then the relationship that the natural frequency decreased with the angle increasing is gotten through the modification parameter, and the conclusion that the angle can be omitted in torsional vibration calculation when it is less than 20 ° is drawn, which provide theoretical support for universal joint design and application in ship propulsion shaft.

  11. 4,4'-Bipyridine-2-(carb-oxy-methyl-sulfan-yl)pyridine-3-carb-oxy-lic acid (1/1).

    Science.gov (United States)

    Jiang, Xian-Rong; Wang, Xiao-Juan; Feng, Yun-Long

    2010-11-27

    In the title co-crystal, C(10)H(8)N(2)·C(8)H(7)NO(4)S, the formate group is coplanar with the pyridyl ring of the acid [dihedral angle = 6.2 (7)°], while the carb-oxy-methyl-sulfanyl group makes a C-S-C-C torsion angle of 70.2 (1)° with the pyridine ring. The dihedral angle between the pyridyl rings of the 4,4'-bipyridine mol-ecule is 27.4 (1)°. The acid and the 4,4'-bipyridine mol-ecules are involved in hydrogen bonding via carb-oxy-lic O and pyridyl N atoms. The structure is further consolidated by inter-molecular C-H⋯O hydrogen bonds, generating a three-dimensional network.

  12. Torsion of a parasitic myoma that developed after abdominal myomectomy.

    Science.gov (United States)

    Cho, In Ae; Baek, Jong Chul; Park, Ji Kwon; Song, Dae Hyun; Kim, Wan Ju; Lee, Yoon Kyoung; Park, Ji Eun; Shin, Jeong Kyu; Choi, Won Jun; Lee, Soon Ae; Lee, Jong Hak; Paik, Won Young

    2016-01-01

    Iatrogenic parasitic myomas are rare. The condition is defined by the presence of multiple smooth-muscle tumorous nodules in the peritoneal cavity. This may be attributable to seeding of myoma particles during uterine surgery. The clinical course is usually indolent. The disease is often asymptomatic and is usually discovered only incidentally. A 38-year-old woman who had undergone abdominal myomectomy 7 months prior presented with acute abdominal pain and a huge pelvic mass. We performed exploratory laparotomy. A parasitic mass 17 cm in diameter with a twisted omental pedicle was identified. En bloc excision of the mass and omentum was performed, followed by total abdominal hysterectomy. Histopathological examination of multiple sections revealed features compatible with an infarcted leiomyoma. Thus, we present a very rare case of an iatrogenic, rapidly growing parasitic myoma complicated by omental torsion (which caused the acute abdominal pain). We also offer a literature review.

  13. Torsion Wave Solutions in Yang-Mielke Theory of Gravity

    CERN Document Server

    Pasic, Vedad

    2015-01-01

    The approach of metric-affine gravity initially distinguishes it from Einstein's general relativity. Using an independent affine connection produces a theory with 10+64 unknowns. We write down the Yang-Mills action for the affine connection and produce the Yang-Mills equation and the so called complementary Yang-Mills equation by independently varying with respect to the connection and the metric respectively. We call this theory the Yang-Mielke theory of gravity. We construct explicit spacetimes with pp-metric and purely axial torsion and show that they represent a solution of Yang-Mills theory. Finally we compare these spacetimes to existing solutions of metric-affine gravity and present future research possibilities.

  14. Origin of methyl torsional potential barrier - An overview

    Indian Academy of Sciences (India)

    Tapanendu Kundu; Biswajit Pradhan; Bhanu P Singh

    2002-12-01

    This paper presents the evolution of views on methyl internal rotation potential barrier. Various mechanisms proposed for the origin of torsional barrier in ethane have been reviewed. Inadequacy of one dimensional description of internal rotation has been highlighted in small methyl conjugated molecules in the light of its multidimensional nature. The effect of skeletal flexing on the picture of barrier formation by dissecting the barrier energy into potential type, virial type and symmetry type is described. The role of and electrons at different stages of molecular flexing is discussed. The analysis identifies the dominant contributions to barrier origin as -bonding changes during rigid rotation and -bonding changes resulting from bond lengthening during methyl group rotation. The contribution of lone pair electrons in determining the preferred structure of the methyl group in imine compounds such as 1-methyl 2-(1H)-pyridinimine is presented.

  15. Dynamical system analysis for nonminimal torsion-matter coupled gravity

    CERN Document Server

    Carloni, Sante; Otalora, Giovanni; Saridakis, Emmanuel N

    2016-01-01

    In this work, we perform a detailed dynamical analysis for the cosmological applications of a nonminimal torsion-matter coupled gravity. Two alternative formalisms are proposed, which enable one to choose between the easier approach for a given problem, and furthermore, we analyze six specific models. In general, we extract fixed points corresponding either to dark-matter dominated, scaling decelerated solutions, or to dark-energy dominated accelerated solutions. Additionally, we find that there is a small parameter region in which the model can experience the transition from the matter epoch to a dark-energy era. These features are in agreement with the observed universe evolution, and make the theory a successful candidate for the description of Nature.

  16. Torsion effects on a relativistic position-dependent mass system

    CERN Document Server

    Vitória, R L L

    2016-01-01

    We analyse a relativistic scalar particle with a position-dependent mass in a spacetime with a space-like dislocation by showing that relativistic bound states solutions can be achieved. Further, we consider the presence of the Coulomb potential and analyse the relativistic position-dependent mass system subject to the Coulomb potential in the spacetime with a space-like dislocation. We also show that a new set of relativistic bound states solutions can be obtained, where there also exists the influence of torsion of the relativistic energy levels. Finally, we investigate an analogue of the Aharonov-Bohm effect for bound states in this position-dependent mass in a spacetime with a space-like dislocation.

  17. Fiber optic stress-independent helical torsion sensor.

    Science.gov (United States)

    Fernandes, Luís A; Grenier, Jason R; Aitchison, J Stewart; Herman, Peter R

    2015-02-15

    Femtosecond laser-fabricated waveguides have been formed into helical paths throughout the cladding of single-mode optical fibers to demonstrate a strain-independent fiber torsion sensor. A comparison between a Bragg grating sensor and a Mach-Zehnder based on helical waveguides (HWs) showed a much weaker twist sensitivity of 1.5 pm/(rad/m) for the grating in contrast with a value of 261 pm/(rad/m) for the interferometer. The HW geometry provided an unambiguous determination of the rotational direction of the twist while facilitating a convenient and efficient means for optical coupling into the single-mode core of the fiber. The flexible three-dimensional writing by the femtosecond laser fabrication method enabled the direct inscription of compact and robust optical cladding devices without the need for combining or splicing multiple-fiber segments.

  18. Torsional oscillations of neutron stars with highly tangled magnetic fields

    CERN Document Server

    Sotani, Hajime

    2015-01-01

    To determine the frequencies of magnetic oscillations in the neutron stars with highly tangled magnetic fields, we derive the perturbation equations. We assume that the field strength of the global magnetic structure is so small that such fields are negligible compared with the tangled fields, which may still be far from a realistic configuration. Then, we systematically examine the spectra of the magnetic oscillations, as varying the magnetic field strength and stellar mass. The frequencies without crust elasticity are completely proportional to the strength of magnetic field, whose proportionality constant depends strongly on the stellar mass. On the other hand, the oscillation spectra with crust elasticity become more complicated, where the frequencies even for weak magnetic fields are different from the crustal torsional oscillations without magnetic fields. For discussing the spectra, the critical field strength can play an important role, which is determined in such a way that the shear velocity is equi...

  19. Non-relativistic correspondence of Dirac equation with external electromagnetic field and space-time torsion

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Bruno; Dias Junior, Mario Marcio [Instituto Federal de Educacacao, Ciencia e Tecnologia Sudeste de Minas Gerais, Juiz de Fora, MG (Brazil)

    2013-07-01

    Full text: The discussion of experimental manifestations of torsion at low energies is mainly related to the torsion-spin interaction. In this respect the behavior of Dirac field and the spinning particle in an external torsion field deserves and received very special attention. In this work, we consider the combined action of torsion and magnetic field on the massive spinor field. In this case, the Dirac equation is not straightforward solved. We suppose that the spinor has two components. The equations have mixed terms between the two components. The electromagnetic field is introduced in the action by the usual gauge transformation. The torsion field is described by the field S{sub μ}. The main purpose of the work is to get an explicit form to the equation of motion that shows the possible interactions between the external fields and the spinor in a Hamiltonian that is independent to each component. We consider that S{sub 0} is constant and is the unique non-vanishing term of S{sub μ}. This simplification is taken just to simplify the algebra, as our main point is not to describe the torsion field itself. In order to get physical analysis of the problem, we consider the non-relativistic approximation. The final result is a Hamiltonian that describes a half spin field in the presence of electromagnetic and torsion external fields. (author)

  20. Faraday rotation and primordial magnetic field constraints on Ultraviolet Lorentz violation with spacetime torsion

    CERN Document Server

    de Andrade, L C Garcia

    2011-01-01

    Recently Kahniashivili et al (2006) presented a unified treatment for ultraviolet Lorentz violation (LV) testing through electromagnetic wave propagation in magnetised plasmas, based on dispersion and rotation measured data. Based on the fact discovered recently by Kostelecky et al (2008), that LV may place constraints on spacetime torsion, in this paper it is shown that on the limit of very low frequency torsion waves, it is possible to constraint torsion from Faraday rotation and CMB on a similar fashion as Minkowski spacetime plus torsion. Here the Maxwells modified equations are obtained by a perturbative method introduced by de Sabbata and Gasperini (1981). Torsion is constraint to $Q_{CMB}\\approx{10^{-18}GeV}$ which is not so stringent as the $10^{-31}GeV$ obtained by Kostelecky et al. However, Gamma Ray Bursts (GBRs) may lead to the more string value obtined by Kostelecky et al. Another interesting constraint on torsion is shown to be placed by galactic dynamo seed magnetic fields. For torsion effects ...

  1. Dose-dependent protective effect of baicalin against testicular torsion-detorsion in rats.

    Science.gov (United States)

    Fouad, A A; Qutub, H O; Jresat, I

    2017-02-01

    Testicular torsion/detorsion induces oxidative/nitrosative stress, inflammation and apoptosis of testicular tissues. Baicalin exerts antioxidant and anti-inflammatory properties. This study investigated the possible protective effect of baicalin against testicular torsion-detorsion injury in rats. Surgical testicular torsion was induced for 2 h, followed by detorsion which was continued for 24 h. Baicalin was administered in three different doses (25, 50 and 100 mg kg(-1) , by intraperitoneal injection). Each dose was given twice, the first 30 min before and the second 12 h after testicular detorsion. Baicalin, in a dose-dependent manner, decreased the torsion/detorsion-induced elevations of testicular malondialdehyde, nitric oxide, tumour necrosis factor-α, BCL2-associated X protein (Bax), cytosolic cytochrome c and caspase-3 and caspase-9 activities. Baicalin, dose dependently, attenuated the reductions of B-cell leucemia/lymphoma 2 (Bcl-2), and glutathione peroxidase and superoxide dismutase activities in testicular tissues resulted from torsion/detorsion. In addition, baicalin ameliorated the histopathological testicular tissue damage and reduced the expression of Fas ligand in rat testes exposed to torsion/detorsion in a dose-dependent manner. It was concluded that baicalin, dose dependently, ameliorated testicular injury induced by torsion/detorsion via its antioxidant, antinitrosative, anti-inflammatory and anti-apoptotic effects.

  2. Human ocular torsion during parabolic flights: an analysis with scleral search coil

    Science.gov (United States)

    Cheung, B. S.; Money, K.; Howard, I.; Kirienko, N.; Johnson, W.; Lackner, J.; Dizio, P.; Evanoff, J.

    1992-01-01

    Rotation of the eyes about the visual axis is known as ocular torsion. A lateral inclination (a "roll") of the head induces ocular torsion in the opposite direction, a response known as ocular counterrolling. For six subjects, we recorded the static (head still) and dynamic (head in oscillatory roll motion) ocular torsion in normal 1 g condition and also during the microgravity and hypergravity periods of parabolic flight, using the electromagnetic scleral search coil technique. With the head still, the direction and magnitude of torsion that occurred in response to microgravity and hypergravity differed substantially from one individual to another, but there was a significant difference in torsional magnitude between the microgravity and hypergravity periods, for all static head positions including the upright position. Under normal 1 g conditions, counterrolling compensated for about 16% of (voluntary) static head roll, while dynamic counterroll was much larger, up to 36% of head roll at 0.55 Hz. With increasing frequency of head oscillation between 0.33 Hz and 0.55 Hz, the gain of counterrolling increased and there was no change in the phase relationship. The gain of dynamic counterroll (in response to voluntary head rolling) was not significantly less in hypogravity, suggesting that on the ground at these frequencies the contribution of gravity and gravity receptors to this reflex is redundant: this reflex is probably driven by the semicircular canals. In some subjects, the torsional displacement in microgravity is accompanied by micro-torsional oscillatory motion.

  3. Transabdominal color doppler ultrasonography: A relevant approach for assessment of effects of uterine torsion in buffaloes

    Directory of Open Access Journals (Sweden)

    Devender

    2016-08-01

    Full Text Available Aim: The present study was conducted on advanced pregnant buffaloes suffering from uterine torsion to assess the status of fetus and uterus by transabdominal ultrasonography, and the findings were compared with normal advanced pregnant buffaloes. Materials and Methods: The study was conducted on 20 clinical cases of uterine torsion and 20 normal advanced pregnant buffaloes (control group. The lower ventral area just lateral to linea alba (on both sides of the udder in standing animals was scanned transabdominally by the two-dimensional convex transducer for various ultrasonographic findings. The data collected were statistically analyzed by “one-way ANOVA” and “independent sample t-test” using computerized SPSS 16.0 software program. Results: Transabdominal ultrasonography revealed dead fetus in 95% uterine torsion cases and proved useful in imaging internal structures of fetuses while no dead fetus was reported in the control group. Size of umbilicus was found significantly decreased (p0.05 in uterine torsion group. Average thickness of the uterine wall and mean pixel values of fetal fluids (echogenicity were found significantly increased (p<0.05 in uterine torsion affected buffaloes in comparison to control group. Conclusion: Status of fetus (whether live or dead, internal status of uterus, and its contents could be determined by transabdominal ultrasonography in uterine torsion cases and thus determining the prognosis of the uterine torsion cases before going for further manipulations. This will also help in taking all the precautions to avoid death of the fetus.

  4. Relationship between the Angle of Repose and Angle of Internal ...

    African Journals Online (AJOL)

    Keywords: Angle of repose, angle of internal friction, granular materials, triaxial compression ... such a granular material is sharp, making a steep .... study. Therefore, grains had to be condi- tioned to the respective moisture contents by adding ...

  5. Global axial-torsional dynamics during rotary drilling

    Science.gov (United States)

    Gupta, Sunit K.; Wahi, Pankaj

    2016-08-01

    We have studied the global dynamics of the bottom hole assembly (BHA) during rotary drilling with a lumped parameter axial-torsional model for the drill-string and a linear cutting force model. Our approach accounts for bit-bounce and stick-slip along with the regenerative effect and is independent of the drill-string and the bit-rock interaction model. Regenerative axial dynamics due to variable depth of cut is incorporated through a functional description of the cut surface profile instead of a delay differential equation with a state-dependent delay. The evolution of the cut surface is governed by a nonlinear partial differential equation (PDE) which is coupled with the ordinary differential equations (ODEs) governing the longitudinal and angular dynamics of the BHA. The boundary condition for the PDE captures multiple regeneration in the event of bit-bounce. Interruption in the torsional dynamics is included by considering separate evolution equations for the various states during the stick period. Finite-dimensional approximation for our coupled PDE-ODE model has been obtained and validated by comparing our results against existing results. Bifurcation analysis of our system reveals a supercritical Hopf bifurcation leading to periodic vibrations without bit-bounce and stick-slip which is followed by solutions involving bit-bounce or stick-slip depending on the operating parameters. Further inroads into the unstable regime leads to a variety of complex behavior including co-existence of periodic and chaotic solutions involving both bit-bounce and stick-slip.

  6. Technology development for the LISA using the UF Torsion Pendulu

    Science.gov (United States)

    Conklin, John W.; Chilton, Andrew; Olatunde, Taiwo; Apple, Stephen; Ciani, Giacomo; Mueller, Guido

    2015-08-01

    Space-based gravitational wave observatories like LISA measure picometer changes in the distances between free falling test masses separated by millions of kilometers caused by gravitational waves. A test mass and its associated sensing, actuation, charge control and caging subsystems are referred to as a gravitational reference sensor (GRS). LISA will observe gravitational wave sources ranging from super-massive black hole mergers to compact galactic binaries in the millihertz region, and LISA science has consistently been ranked in the top two for future large space missions in the last two NASA astrophysics decadal reviews. With the 2015 launch of LISA Pathfinder (LPF) and the expected detection of gravitational waves by aLIGO and/or Pulsar Timing Arrays within in the next several years, this can arguably be called the decade of gravitational waves. Following a successful demonstration of the baseline LISA GRS by LPF, the measurement principle will be carried forward, but improvements in several GRS components are possible over the next ten years that will lead to cost savings and potential noise reductions. The UF LISA group has constructed the UF Torsion Pendulum to increase U.S. competency in this critical area and to have a facility where new technologies can be developed and evaluated. This experimental facility is based on the design of a similar facility at the University of Trento, and consists of a vacuum enclosed torsion pendulum that suspends mock-ups of the LISA test masses, surrounded by electrode housings. This presentation will describe this facility, focusing on its mechanical design, capacitive sensing and electrostatic actuation systems, and overall acceleration noise performance

  7. Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling

    Science.gov (United States)

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

    2014-06-01

    We obtain quantum geometries on a vacuum created pair of a (DDbar)3-brane, at a Big Bang singularity, by a local two form on a D4-brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DDbar)-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D4-brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.

  8. Modeling and testing miniature torsion specimens for SiC joining development studies for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Henager, C.H., E-mail: chuck.henager@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States); Nguyen, B.N.; Kurtz, R.J.; Roosendaal, T.J.; Borlaug, B.A. [Pacific Northwest National Laboratory, Richland, WA (United States); Ferraris, M.; Ventrella, A. [Politecnico di Torino, Torino (Italy); Katoh, Y. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2015-11-15

    The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. Miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti{sub 3}SiC{sub 2} + SiC joints with SiC and tested in torsion-shear prior to and after neutron irradiation. However, many miniature torsion specimens fail out-of-plane within the SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated strengths to determine irradiation effects. Finite element elastic damage and elastic–plastic damage models of miniature torsion joints are developed that indicate shear fracture is more likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated test data for a variety of joint materials. The unirradiated data includes Ti{sub 3}SiC{sub 2} + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. The implications for joint data based on this sample design are discussed. - Highlights: • Finite element damage models developed and applied to understand miniature torsion specimen. • Damage models correctly predict torsion joint failure locations for wide range of materials. • Tests of strong, stiff ceramic joints will not produce accurate shear strength values. • Miniature torsion specimen has diminished test utility but still valuable.

  9. Gastrointestinal torsions and intussusception in northern koalas (Phascolarctos cinereus) at San Diego Zoo (1976-2012).

    Science.gov (United States)

    Joyce-Zuniga, Nicole M; Roesler, Jennifer; Andrus, Chris Hamlin; Sutherland-Smith, Meg; Rideout, Bruce A; Pye, Geoffrey W

    2014-03-01

    The recent classification as threatened status of the northern koala (Phascolarctos cinereus) by the Australian Government highlights the importance of the conservation and health management of this iconic Australian marsupial. This case series describes gastrointestinal torsion and intussusception in six northern koalas (three males, three females, 2-11 yr old) at the San Diego Zoo from 1976 to 2012. Two koalas died shortly after presentation. Diagnoses of ileocecal intussusception, resulting from enteritis in one case and cecal torsion in the other, were made at postmortem examination. One koala died 4 days after an exploratory laparotomy, with negative findings, and an acute double colonic intussusception was diagnosed at postmortem examination. Two small intestinal mesenteric torsion and one proximal colon mesenteric torsion cases were successfully corrected surgically. In the case of colonic mesenteric torsion, the koala had recurrent clinical signs 2 wk later, and a second surgery requiring resection and anastomosis of ischemic jejunum was performed, with the koala dying shortly afterward. One koala with small intestinal torsion had a recurrence of torsion 22 mo later and subsequently died. The koala with the second case of small intestinal torsion remains alive 14 mo postsurgical correction. All six koalas presented with signs of colic that included anorexia, lethargy, depression, acute abdominal distension, abdominal stretching, decreased fecal output, open-mouth gasping, or a combination of symptoms. Abdominal radiographs may show stacked gastrointestinal linear gas patterns and contrast stasis. Prevalence of torsion and intussusception is low at this institution (2%), although recurrence in individuals is common (50%) and overall survival is poor (83%), which emphasizes the importance of timely recognition, surgical correction, and postoperative management. While inciting etiologies were unable to be determined in these cases, monitoring generalized

  10. Optical monitoring of testicular torsion using a miniaturized near infrared spectroscopy sensor

    Science.gov (United States)

    Shadgan, Babak; Kajbafzadeh, Majid; Nigro, Mark; Kajbafzadeh, A. M.; Macnab, Andrew

    2017-02-01

    Background: Testicular torsion is an acute urological emergency occurring in children and adolescents. Accurate and fast diagnosis is important as the resulting ischemia can destroy the testis. Currently, Doppler ultrasound is the preferred diagnostic method. Ultrasound is not readily available in all centers which may delay surgical treatment. In this study, a rat model was used to examine the feasibility and sensitivity of using spatially-resolved near infrared spectroscopy (SR-NIRS) with a custom-made miniaturized optical sensor probe to detect and study changes in testicular hemodynamics and oxygenation during three degrees of induced testicular torsion, and after detorsion. Methods: Eight anesthetized rats (16 testes) were studied using SR-NIRS with the miniaturized optical probe applied directly onto the surface of the surgically exposed testis during 360, 720 and 1080 degrees of torsion followed by detorsion. Oxygenated, deoxygenated and total hemoglobin and TOI% were studied pre-and post-manipulations. Results: NIRS monitoring reflected acute testicular ischemia and hypoxia on induction of torsion, and tissue reperfusionreoxygenation after detorsion. Testicular torsion at 720 degrees induced the maximum observed degree of hypoxic changes. In all cases, rhythmic changes were observed in the NIRS signals before inducing torsion; these disappeared after applying 360 degrees of torsion and did not reappear after detorsion. Conclusion: This animal study indicates that SR-NIRS monitoring of the testes using a directly applied miniature sensor is a feasible and sensitive method to detect testicular ischemia and hypoxia immediately after torsion occurs, and testicular reperfusion upon detorsion. This study offers the potential for a SR-NIRS system with a miniaturized sensor to be explored further as a rapid, noninvasive, optical method for detecting testicular torsion in children.

  11. Determining the shear fracture properties of HIP joints of reduced-activation ferritic/martensitic steel by a torsion test

    Science.gov (United States)

    Nozawa, Takashi; Noh, Sanghoon; Tanigawa, Hiroyasu

    2012-08-01

    Hot isostatic pressing (HIP) is a key technology used to fabricate a first wall with cooling channels for the fusion blanket system utilizing a reduced-activation ferritic/martensitic steel. To qualify the HIPped components, small specimen test techniques are beneficial not only to evaluate the thin-wall cooling channels containing the HIP joint but also to use in neutron irradiation studies. This study aims to develop the torsion test method with special emphasis on providing a reasonable and comprehensive method to determine interfacial shear properties of HIP joints during the torsional fracture process. Torsion test results identified that the torsion process shows yield of the base metal followed by non-elastic deformation due to work hardening of the base metal. By considering this work hardening issue, we propose a reasonable and realistic solution to determine the torsional yield shear stress and the ultimate torsional shear strength of the HIPped interface. Finally, a representative torsion fracture process was identified.

  12. Cofactor-binding sites in proteins of deviating sequence: comparative analysis and clustering in torsion angle, cavity, and fold space.

    Science.gov (United States)

    Stegemann, Björn; Klebe, Gerhard

    2012-02-01

    Small molecules are recognized in protein-binding pockets through surface-exposed physicochemical properties. To optimize binding, they have to adopt a conformation corresponding to a local energy minimum within the formed protein-ligand complex. However, their conformational flexibility makes them competent to bind not only to homologous proteins of the same family but also to proteins of remote similarity with respect to the shape of the binding pockets and folding pattern. Considering drug action, such observations can give rise to unexpected and undesired cross reactivity. In this study, datasets of six different cofactors (ADP, ATP, NAD(P)(H), FAD, and acetyl CoA, sharing an adenosine diphosphate moiety as common substructure), observed in multiple crystal structures of protein-cofactor complexes exhibiting sequence identity below 25%, have been analyzed for the conformational properties of the bound ligands, the distribution of physicochemical properties in the accommodating protein-binding pockets, and the local folding patterns next to the cofactor-binding site. State-of-the-art clustering techniques have been applied to group the different protein-cofactor complexes in the different spaces. Interestingly, clustering in cavity (Cavbase) and fold space (DALI) reveals virtually the same data structuring. Remarkable relationships can be found among the different spaces. They provide information on how conformations are conserved across the host proteins and which distinct local cavity and fold motifs recognize the different portions of the cofactors. In those cases, where different cofactors are found to be accommodated in a similar fashion to the same fold motifs, only a commonly shared substructure of the cofactors is used for the recognition process. Copyright © 2011 Wiley Periodicals, Inc.

  13. MERA: a webserver for evaluating backbone torsion angle distributions in dynamic and disordered proteins from NMR data

    Energy Technology Data Exchange (ETDEWEB)

    Mantsyzov, Alexey B. [M.V. Lomonosov Moscow State University, Faculty of Fundamental Medicine (Russian Federation); Shen, Yang; Lee, Jung Ho [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States); Hummer, Gerhard [Max Planck Institute of Biophysics (Germany); Bax, Ad, E-mail: bax@nih.gov [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)

    2015-09-15

    MERA (Maximum Entropy Ramachandran map Analysis from NMR data) is a new webserver that generates residue-by-residue Ramachandran map distributions for disordered proteins or disordered regions in proteins on the basis of experimental NMR parameters. As input data, the program currently utilizes up to 12 different parameters. These include three different types of short-range NOEs, three types of backbone chemical shifts ({sup 15}N, {sup 13}C{sup α}, and {sup 13}C′), six types of J couplings ({sup 3}J{sub HNHα}, {sup 3}J{sub C′C′}, {sup 3}J{sub C′Hα}, {sup 1}J{sub HαCα}, {sup 2}J{sub CαN} and {sup 1}J{sub CαN}), as well as the {sup 15}N-relaxation derived J(0) spectral density. The Ramachandran map distributions are reported in terms of populations of their 15° × 15° voxels, and an adjustable maximum entropy weight factor is available to ensure that the obtained distributions will not deviate more from a newly derived coil library distribution than required to account for the experimental data. MERA output includes the agreement between each input parameter and its distribution-derived value. As an application, we demonstrate performance of the program for several residues in the intrinsically disordered protein α-synuclein, as well as for several static and dynamic residues in the folded protein GB3.

  14. 11-cis retinal torsion: A QTAIM and stress tensor analysis of the S1 excited state

    Science.gov (United States)

    Maza, Julio R.; Jenkins, Samantha; Kirk, Steven R.

    2016-05-01

    We investigate torsion about the C11-C12 bond mid-point for the S1 state of 11-cis retinal, using a QTAIM and stress tensor analysis. The QTAIM and stress tensor responses to a torsion ±α increase at a faster rate for the preferred direction of torsion though the CI seam. A QTAIM and stress tensor vector-based analysis provides an alternative way of characterising the asymmetry of the S1 potential energy surface. In the vicinity of the CI seam the ellipticity ε attained minimum values. The application of this analysis to molecular rotary motors is briefly discussed.

  15. Spontaneous Compactification to Robertson-Walker Universe Due To Dynamical Torsion

    CERN Document Server

    Malyshenko, V O; Malyshenko, Viktoria; Ricoy, Domingo Marin

    1997-01-01

    We investigate multidimensional gravity with the Gauss-Bonnet term and with torsion on the space of extra dimensions chosen to be the group manifold of a simple Lie group. We take the Robertson-Walker ansatz for the 4-dimensional space-time and study the potential of a dilaton and torsion fields. It is shown that for certain values of the parameters of the initial theory the potential has classically stable minima, corresponding to the spontaneous compactification of the extra dimensions. However, these minima have zero torsion.

  16. Combined deformation of filament-wound cylinder and application to torsion vibration control

    Institute of Scientific and Technical Information of China (English)

    李玉兰

    2002-01-01

    The combined deformation and mechanical propetries of filament-wound cylinder of filament reinforced composite materials are investigated.A method of using filament-winding composited to reduce the amplitude of torsion vibration in the case of special stimulated vibration is established.A design formula of anisotropic filament-wound cylinder to reduce the torsion vibration of axle components is obtained.The results indicate that by puting the filament-wound cylinder on an axis,the torsion vibration of the axis can be reduced effectively.

  17. Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review

    Directory of Open Access Journals (Sweden)

    Vedran Budinski

    2017-02-01

    Full Text Available Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.Invited Paper

  18. Time-Resolved Torsional Relaxation of Spider Draglines by an Optical Technique

    Science.gov (United States)

    Emile, O.; Floch, A. Le; Vollrath, F.

    2007-04-01

    The sensitivity of the torsional pendulum demonstrates the self-shape-memory effect in different types of spider draglines. Here we report the time-resolved noncovalent bonds recovery in the protein structure. The torsional dynamics of such multilevel structure governed by reversible interactions are described in the frame of a nested model. Measurement of three different relaxation times confirms the existence of three energy storage levels in such two protein spidroin systems. Torsion opens the way to further investigations towards unraveling the tiny torque effects in biological molecules.

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

    CERN Document Server

    Capozziello, Salvatore; Vignolo, Stefano

    2013-01-01

    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

  20. STUDY ON INFLUENCE OF BENDING-TORSION COUPLING IN AN IMPACTING-RUB ROTOR SYSTEM

    Institute of Scientific and Technical Information of China (English)

    孙政策; 徐健学; 周桐; 谭宁

    2003-01-01

    A mathematical model of an impacting-rub rotor system with bending-torsion coupling was established. It was compared with the model without bending-torsion coupling through the nodern nonlinear dynamic theory. It is observed that periodical, chaotic,period adding phenomena in them and the two models have a similar bifurcation process in their bifurcation figures. But the influence of bending-torsion on the dynmaic characteristics of the system is not neglected. The results have considerable meanings to analyze and improve the characteristics of an impacting-rub rotor system.