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.
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.
Cyclic Stress-Strain Studies of Metals in Torsion
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
The effect of cyclic torsion on the dislocation structure of drawn mild steel
Directory of Open Access Journals (Sweden)
Maria Teresa Paulino Aguilar
2006-09-01
Full Text Available Cold forming is usually associated with the "work hardening" of the material being formed. The work hardening behavior of metals subject to complex processing paths is different from that in monotonic deformation. The results show that, after some initial hardening, there is a possibility that further deformation will cause softening in the material ("work softening". Recent work showed that cyclic torsion applied to drawn products causes changes in the subsequent tensile behavior of low carbon steel, and that the effect will depend on the previous "history" of the material. For annealed samples, the cyclic torsion leads to an increase in the yield strength, but does not affect the tensile strength and elongation. For the case of previously drawn bars, the cyclic deformation caused a decrease in the yield and tensile strength and an increase in the total elongation. The present paper discusses the dislocation structure changes associated with different strain paths in mild steel.
Deformation and rupture of stainless steel under cyclic, torsional creep
Rees, DWA
2008-01-01
Copyright 2008 @ Engineering Integrity Society. Recent results from a long-term, strain-limited, cyclic creep test program upon stainless steel tubes are given. The test conditions employed were: constant temperature 500 °C, shear stress Ƭ = ± 300 MPa and shear strain limits ƴ = ± 4%. It is believed that a cyclic creep behaviour for the material has been revealed that has not been reported before in the literature. That is, the creep curves for stainless steel under repeated, shear stress...
Modelling of Stress-Strain Relationship of Toyoura Sand in Large Cyclic Torsional Loading
Hong Nam, Nguyen; Koseki, Junichi
The relationships between normalized shear stress and plastic shear strain of air-dried, dense Toyoura sand measured during large amplitude cyclic torsional loading with using local strain measurement could be well simulated numerically by the proportional rule combined with the drag rule. The proportional rule is an extended version of the Masing's second rule and can account for unsymmetrical stress strain behavior about neutral axis. The drag rule can account for strain hardening in cyclic loadings. Use of the newly proposed hypoelastic model for the quasi-elastic properties, the backbone curve using general hyperbolic equation or newly proposed lognormal equation for monotonic loading behavior, and the combination of the proportional rule and the drag rule for cyclic loading behavior would enable more precise simulation of deformation properties than before.
Torsional and cyclic fatigue resistances of glide path preparation instruments: G-file and PathFile.
Sung, Sang Yup; Ha, Jung-Hong; Kwak, Sang-Won; Abed, Rashid El; Byeon, Kyeongmin; Kim, Hyeon-Cheol
2014-01-01
This study aimed to compare cyclic fatigue and torsional resistances of glide path creating instruments with different tapers and tip sizes. Two sizes (G1 and G2) from G-File system and three sizes (PathFile #1, #2, and #3) from PathFile system were used for torsional resistance and cyclic fatigue resistance tests (n = 10). The torsional resistance was evaluated at 2-, 3-, 4-, 5-, and 6-mm from the file tip by plotting the torsional load changes until fracture by rotational loading of 2 rpm. The cyclic fatigue resistance was compared by measuring the number of cycles to failure. Data were analyzed statistically using one-way ANOVA and Duncan's post-hoc comparison. The length of the fractured file fragment was also measured. All fractured fragments were observed under a scanning electron microscope (SEM). Although G-2 file showed a lower torsional strength than PathFile #3 at 2- and 3-mm levels (p 0.05). The smaller files of each brand had a significantly higher cyclic fatigue resistance than the bigger ones (p files (p < 0.05). While G-1 had a similar fatigue resistance as PathFile #3, G-2 showed the lowest and PathFile #1 showed the highest resistances among the tested groups (p < 0.05). The SEM examination showed typical appearances of cyclic fatigue and torsional fractures, regardless of the tested levels. Clinicians may consider the instruments' sizes for each clinical case in order to get efficient glide path with minimal risk of fracture.
Repetitive Cyclic Potentiodynamic Polarization Scan Results for Reduced Sample Volume Testing
Energy Technology Data Exchange (ETDEWEB)
LaMothe, Margaret E. [Washington River Protection Solutions, Richland, WA (United States)
2016-03-15
This report is the compilation of data gathered after repetitively testing simulated tank waste and a radioactive tank waste sample using a cyclic potentiodynamic polarization (CPP) test method to determine corrosion resistance of metal samples. Electrochemistry testing of radioactive tank samples is often used to assess the corrosion susceptibility and material integrity of waste tank steel. Repetitive testing of radiological tank waste is occasionally requested at 222-S Laboratory due to the limited volume of radiological tank sample received for testing.
Mechanical stability of roll-to-roll printed solar cells under cyclic bending and torsion
DEFF Research Database (Denmark)
Finn, Mickey; Martens, Christian James; Zaretski, Aliaksandr V.
2018-01-01
The ability of printed organic solar cells (OSCs) to survive repeated mechanical deformation is critical to large-scale implementation. This paper reports an investigation into the mechanical stability of OSCs through bending and torsion testing of whole printed modules. Two types of modules...... strain cycles. Failure during torsion occurs through crack propagation initiated at stress concentrations on the edges of the module that were imposed by their rectangular geometry and ultimately leads to bifurcation of the entire module. Rather than the differences in electrode materials...
Mechanical stability of roll-to-roll printed solar cells under cyclic bending and torsion
DEFF Research Database (Denmark)
Finn, Mickey; Martens, Christian James; Zaretski, Aliaksandr V.
2018-01-01
The ability of printed organic solar cells (OSCs) to survive repeated mechanical deformation is critical to large-scale implementation. This paper reports an investigation into the mechanical stability of OSCs through bending and torsion testing of whole printed modules. Two types of modules...
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.
Directory of Open Access Journals (Sweden)
M. Vaško
2017-01-01
Full Text Available The contribution deals with a research into the fatigue life of weld joints of AlMgSi07.F25 aluminium alloy. The paper will present unique biaxial testing equipment, process of preparation of specimen rods for fatigue tests, and the results of fatigue life assessment for the aluminium alloy during cyclic bending-torsion loading. Fatigue tests under constant amplitude loading were performed on a special electromechanical machine with a suitable clamping system. The obtained fatigue curves were compared with the most widely-known fatigue criteria such as LIU, F-S and B-M.
Kramkowski, Thomas R; Bahcall, James
2009-03-01
The purpose of this in vitro study was to compare the torsional stress and cyclic fatigue characteristics of ProFile GT (Dentsply Tulsa Dental, Tulsa, OK) and ProFile GT Series X (Dentsply Tulsa Dental). Files of 0.04 and 0.06 taper, 25 mm in length, and ISO sizes of 20 and 30 tips were compared (n = 25 per test group). Torque stress resistance was evaluated by measuring the torque in gram-centimeters (g-cm) and angle of deflection (degrees of rotation) required for instrument separation with use of a torsiometer instrument. Cyclic fatigue was determined by recording the time until breakage of a file rotating in a simulated canal with an applied 45 degrees or 60 degrees curve. The files were operated in a cyclic fatigue instrument that simulated clinical rotary file usage with a constant cyclical axial motion. There was no statistical difference (p > 0.05) when comparing the torque (g-cm) required to induce a torsional failure of ProFile GT and ProFile GT Series X files of identical file sizes. The angle of deflection (degrees of rotation) of ProFile GT was significantly greater (p X for all file sizes tested except 20/.04 (p > 0.05). There was no statistical difference (p > 0.05) in cyclic fatigue failure for ProFile GT and ProFile GT Series X in a canal with a curvature of 45 degrees . In the 60 degrees canal curvature, ProFile GT was found to be significantly more resistant (p = 0.005) to fracture because of cyclic fatigue than ProFile GT Series X for file size 30/.06 and significant (p files sizes 20/.06 and 30/.04. There was no difference (p > 0.05) in cyclic fatigue resistance in the 60 degrees canal for ProFile GT and ProFile GT Series X for file size 20/.04.
Kahn, Cyril J F; Ziani, Kahina; Zhang, Ye Min; Liu, Jian; Tran, Nguyen; Babin, Jérôme; de Isla, Natalia; Six, Jean-Luc; Wang, Xiong
2013-01-01
This study aims to investigate the in vitro degradation of a poly(L-lactic-co-glycolic acid)-poly(L-lactic-co-ϵ-caprolactone) (PLGA-PLCL) composite scaffold's mechanical properties under static culture condition and 2 h period per day of traction-torsion cyclic culture conditions of simultaneous 10% uniaxial strain and 90° of torsion cycles at 0.33 Hz. Scaffolds were cultured in static conditions, during 28 days, with or without cell seeded or under dynamic conditions during 14 days in a bioreactor. Scaffolds' biocompatibility and proliferation were investigated with Alamar Blue tests and cell nuclei staining. Scaffolds' mechanical properties were tested during degradation by uniaxial traction test. The PLGA-PLCL composite scaffold showed a good cytocompatibility and a high degree of colonization in static conditions. Mechanical tests showed a competition between two process of degradation which have been associated to hydrolytic and enzymatic degradation for the reinforce yarn in poly(L-lactic-co-glycolic acid) (PLGA). The enzymatic degradation led to a decrease effect on mechanical properties of cell-seeded scaffolds during the 21st days, but the hydrolytic degradation was preponderant at day 28. In conclusion, the structure of this scaffold is adapted to culture in terms of biocompatibility and cell orientation (microfiber) but must be improved by delaying the degradation of it reinforce structure in PLGA.
Vafaeian, Saeed; Fattah-alhosseini, Arash; Keshavarz, Mohsen K.; Mazaheri, Yousef
2017-01-01
In this study, it was revealed that the electrochemical behavior of AISI 430 ferritic stainless steel can be modified and improved to a large extent by the application of repetitive cyclic voltammetry in the anodic polarization branch of the alloy. The efficiency of this method was evaluated on the basis of the alloy grain size which is of great importance in corrosion studies. In fact, a coarse grain structure versus a fine grain structure was the subject of the used surface treatment method. Coarsening and refining of the grain size were conducted through a heat treatment and an advanced thermomechanical process. On the basis of cyclic voltammetry tests and also the electrochemical tests performed after that, it was shown that cyclic voltammetry had a significant improving effect on the passive behavior of both fine- and coarse-grained samples. Moreover, superior behavior of fine-grained sample in comparison with coarse-grained one was distinguished by its smaller cyclic voltammogram loops, more noble free potentials, larger capacitive arcs in the Nyquist plots, and less charge carrier densities within the passive film.
Vafaeian, Saeed; Fattah-alhosseini, Arash; Keshavarz, Mohsen K.; Mazaheri, Yousef
2017-02-01
In this study, it was revealed that the electrochemical behavior of AISI 430 ferritic stainless steel can be modified and improved to a large extent by the application of repetitive cyclic voltammetry in the anodic polarization branch of the alloy. The efficiency of this method was evaluated on the basis of the alloy grain size which is of great importance in corrosion studies. In fact, a coarse grain structure versus a fine grain structure was the subject of the used surface treatment method. Coarsening and refining of the grain size were conducted through a heat treatment and an advanced thermomechanical process. On the basis of cyclic voltammetry tests and also the electrochemical tests performed after that, it was shown that cyclic voltammetry had a significant improving effect on the passive behavior of both fine- and coarse-grained samples. Moreover, superior behavior of fine-grained sample in comparison with coarse-grained one was distinguished by its smaller cyclic voltammogram loops, more noble free potentials, larger capacitive arcs in the Nyquist plots, and less charge carrier densities within the passive film.
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...
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
Directory of Open Access Journals (Sweden)
Samantha C W Chan
Full Text Available The spine is routinely subjected to repetitive complex loading consisting of axial compression, torsion, flexion and extension. Mechanical loading is one of the important causes of spinal diseases, including disc herniation and disc degeneration. It is known that static and dynamic compression can lead to progressive disc degeneration, but little is known about the mechanobiology of the disc subjected to combined dynamic compression and torsion. Therefore, the purpose of this study was to compare the mechanobiology of the intervertebral disc when subjected to combined dynamic compression and axial torsion or pure dynamic compression or axial torsion using organ culture. We applied four different loading modalities [1. control: no loading (NL, 2. cyclic compression (CC, 3. cyclic torsion (CT, and 4. combined cyclic compression and torsion (CCT] on bovine caudal disc explants using our custom made dynamic loading bioreactor for disc organ culture. Loads were applied for 8 h/day and continued for 14 days, all at a physiological magnitude and frequency. Our results provided strong evidence that complex loading induced a stronger degree of disc degeneration compared to one degree of freedom loading. In the CCT group, less than 10% nucleus pulposus (NP cells survived the 14 days of loading, while cell viabilities were maintained above 70% in the NP of all the other three groups and in the annulus fibrosus (AF of all the groups. Gene expression analysis revealed a strong up-regulation in matrix genes and matrix remodeling genes in the AF of the CCT group. Cell apoptotic activity and glycosaminoglycan content were also quantified but there were no statistically significant differences found. Cell morphology in the NP of the CCT was changed, as shown by histological evaluation. Our results stress the importance of complex loading on the initiation and progression of disc degeneration.
Repetition in Waiting for Godot
Institute of Scientific and Technical Information of China (English)
李想; 魏妍
2015-01-01
Waiting for Godot is one of the most famous plays written by Samuel Barclay Beckett, and also is the founding work of“Theatre of the Absurd”. In the drama, repetitive phenomena shed light on the whole construction considerably. All the charac-ters were helpless and unthinking. Their dialogues were simple, nonsense and repetitive. Two scenes were cyclical. Repetition was used subtly in order to express the theme of the play, showing mental crisis after depravation of WWII.
Institute of Scientific and Technical Information of China (English)
HUANG Yu-Xin; YANG Yu-Jun; WU Bin; GUO Fu-Ming; ZHU Qi-Ren
2008-01-01
@@ Using a variational method, we derive the optimal population distribution of angular momentum eigenstates for any given population range in a rotational wavepacket within the field-free cyclic state orientation framework.Correspondingly, we devise a train of half-cycle pulse clusters to purposively make the structure of the computed wavepacket approach the optimal population distribution, so that we can now utilize much more powerful means to realize an ideal orientation goal.
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.
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.
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.
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-Mller 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.
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.
Analytical and numerical models to predict the behavior of unbonded flexible risers under torsion
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.
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.
[Omental torsion. Case Report].
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.
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.)
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.
Higher Franz-Reidemeister torsion
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.
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.
"Exotic" black holes with torsion
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.
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.
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
Energy Technology Data Exchange (ETDEWEB)
Klumpp, S.; Eifler, D.; Macherauch, E. (Karlsruhe Univ. (T.H.) (Germany, F.R.). Inst. fuer Werkstoffkunde 1)
1990-05-01
Cyclic deformation behaviour of a normalized steel SAE 4140 in shear strain-controlled torsion is characterized by cyclic softening and cyclic hardening. If mean shear stresses are superimposed to an alternating shear stress, cycle-dependent creep occurs, and the number of cycles to failure decreases. In shear strain-controlled torsional loading, mean stresses are observed to relax nearly to zero within a few cycles. Fatigue life is not influenced by mean shear strains. (orig.).
Constitutive Model for Multiaxial Ratcheting Predictions of Cyclic Softening Weld Metal
Institute of Scientific and Technical Information of China (English)
GAO Hong; CHEN Xu; JIAO Rong
2005-01-01
A series of fully reversed axial, torsional strain-controlled cyclic tests and two multiaxial ratcheting tests were conducted on weld metal specimens using an Instron8521 tension-torsional servo-controlled testing machine. The weld metal showed clear cyclic softening under axial, torsional and multiaxial loading. A modified kinematic hardening rule was proposed in which a multiaxial-loading-dependent parameter incorporated the radial evanescence term of the Burlet-Cailletaud mode with the Ohno-Wang kinematic hardening rule to predict the multiaxial ratcheting effects. The introduction of yield stress evolved with accumulated plasticity strain enables the model to predict cyclic plasticity behavior of cyclic softening or cyclic hardening materials. Thus modified model considers the isotropic hardening as well as kinematic hardening of yield surface, and it can present description of plasticity behavior and ratcheting of cyclic softening and cyclic hardening materials well under multiaxial loading.
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...
TORSIONAL DEFORMATION AND FATIGUE BEHAVIOUR OF 6061 ALUMINIUM ALLOY
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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.
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....
Cyclic Shearing Deformation Behavior of Saturated Clays
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The apparatus for static and dynamic universal triaxial and torsional shear soil testing is employed to perform stress-controlled cyclic single-direction torsional shear tests and two-direction coupled shear tests under unconsolidated-undrained conditions. Through a series of tests on saturated clay, the effects of initial shear stress and stress reversal on the clay's strain-stress behavior are examined, and the behavior of pore water pressure is studied. The experimental results indicate that the patterns of stress-strain relations are distinctly influenced by the initial shear stress in the cyclic single-direction shear tests. When the initial shear stress is large and no stress reversal occurs, the predominant deformation behavior is characterized by an accumulative effect. When the initial shear stress is zero and symmetrical cyclic stress occurs, the predominant deformation behavior is characterized by a cyclic effect. The pore water pressure fluctuates around the confining pressure with the increase of cycle number. It seems that the fluctuating amplitude increases with the increase of the cyclic stress. But a buildup of pore water pressure does not occur. The deformations of clay samples under the complex initial and the cyclic coupled stress conditions include the normal deviatoric deformation and horizontal shear deformation, the average deformation and cyclic deformation. A general strain failure criterion taking into account these deformations is recommended and is proved more stable and suitable compared to the strain failure criteria currently used.
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....
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.
Torsion Effects and LLG Equation
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.
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...
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....
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.
Assaf, Sami H
2010-01-01
A classic problem in enumerative combinatorics is to count the number of derangements, that is, permutations with no fixed point. Inspired by a recent generalization to facet derangements of the hypercube by Gordon and McMahon, we generalize this problem to enumerating derangements in the wreath product of any finite cyclic group with the symmetric group. We also give q- and (q, t)-analogs for cyclic derangements, generalizing results of Brenti and Gessel.
Index Theorems on Torsional Geometries
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.
TORSION OF HEMATOSALPINX WITH HEMOPERITONEUM
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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.
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....
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....
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....
Multiaxial elastoplastic cyclic loading of austenitic 316L steel
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V. Mazánová
2017-04-01
Full Text Available Cyclic stress-strain response and fatigue damage character has been investigated in austenitic stainless steel 316L. Hollow cylindrical specimens have been cyclically deformed in combined tension-compression and torsion under constant strain rate condition and different constant strain and shear strain amplitudes. In-phase and 90° out-of-phase cyclic straining was applied and the stress response has been monitored. Cyclic hardening/softening curves were assessed in both channels. Cyclic softening followed for higher strain amplitudes by long-term cyclic hardening was observed. Cyclic stress-strain curves were determined. Study of the surface damage in fractured specimens revealed the types and directions of principal cracks and the sources of fatigue crack initiation in slip bands.
Gooyers, Chad E; Callaghan, Jack P
2015-10-15
Most in vitro studies are limited in the ability to partition intervertebral disc (IVD) height loss from total specimen height loss since the net changes in the actuator position of the materials testing system simply reflect net changes to functional spinal units (FSUs) used for testing. Three levels of peak compressive force, three cycle rates and two dynamic postural conditions were examined using a full-factorial design. Cyclic compressive force was applied using a time-varying waveform with synchronous flexion/extension for 5000 cycles. Surface scans from the anterior aspect of the IVD were recorded in a neutral and flexed posture before and after the cyclic loading protocol using a 3D laser scanner to characterise changes in IVD height loss and bulging. A significant three-way interaction (p=0.0092) between the magnitude of peak compressive force, cycle rate and degree of postural deviation was observed in cycle-varying specimen height loss data. A significant main effect of peak compressive force (p=0.0003) was also observed in IVD height loss calculated from the surface profiles of the IVD. The relative contribution of IVD height loss (measured on the anterior surface) to total specimen height loss across experimental conditions varied considerably, ranging from 19% to 58%. Postural deviation was the only factor that significantly affected the magnitude of peak AF bulge (p=0.0016). This investigation provides evidence that total specimen height loss is not an accurate depiction of cycle-varying changes in the IVD across a range of in vivo scenarios that were replicated with in vitro testing.
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%.
Torsional Phacoemulsification and Tip Selection
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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
Evans, Dennis H.; And Others
1983-01-01
Cyclic voltammetry is a simple experiment that has become popular in chemical research because it can provide useful information about redox reactions in a form which is easily obtained and interpreted. Discusses principles of the method and illustrates its use in the study of four electrode reactions. (Author/JN)
Evans, Dennis H.; And Others
1983-01-01
Cyclic voltammetry is a simple experiment that has become popular in chemical research because it can provide useful information about redox reactions in a form which is easily obtained and interpreted. Discusses principles of the method and illustrates its use in the study of four electrode reactions. (Author/JN)
Lobar torsion after lung transplantation
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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.
Torsional Carbon Nanotube Artificial Muscles
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.
Institute of Scientific and Technical Information of China (English)
顾晓强; 杨峻; 黄茂松; 高广运
2016-01-01
利用弯曲元、共振柱和循环扭剪试验联合测定了不同围压和密实度条件下干砂的小应变剪切模量，研究了弯曲元试验中输出信号的特性和各种信号分析方法确定剪切波传播时间的可靠性，并对比了不同试验的结果。研究结果表明，在共振柱试验时，需要考虑系统刚度对试验结果的影响，特别当试样刚度较大时。弯曲元输出信号中最先到达的是近场效应，其初始极化方向跟剪切波相反。近场效应随着输入频率的增加有一定程度的减小，但不会消失。实际试验中建议输入频率不断增加，直至输出信号比较稳定。值得注意的是，剪切初达波的振幅可能远小于后续振动，因此容易造成初达波的误判。时域初达波法能比较可靠准确地确定剪切波的传播时间，波峰法、交互相关法和交互功率法结果均随输入频率有较大波动，不能可靠地确定剪切波的传播时间。对比试验表明，弯曲元、共振柱和循环扭剪试验确定小应变剪切模量对细砂和粗砂均吻合良好，初步表明砂土粒径对不同试验方法结果的一致性没有影响。%Bender element (BE), resonant column (RC) and cyclic torsional shear (TS) tests are performed to measure the small strain shear modulus of dry sands. Thecharacteristics of the received signals in BE tests are investigated, and different interpretation methods are used to determine the travel time of shear waves.The results indicate that it is important to account for the compliance of the testing system in RC tests, especially when the specimen is stiff. In BE tests, the near fieldcomponent arrives first and its initial polarization is opposite to that of the input signal. The near flied decreases as the input frequency increases, but it always exists. Inpractice, it isrecommended that the input frequency should increase continuously until the output signal becomes stable. Note that
Constraining Torsion with Gravity Probe B
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...
Torsional Weyl-Dirac Electrodinamics
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.
Uterine torsion in term pregnancy
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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
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...
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.
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.
Marosek, Konrad; Balcerzak, Adam
2015-01-01
Starting with the idea of regularization of singularities due to the variability of the fundamental constants in cosmology we first study the cyclic universe models. We find two models of oscillating mass density and pressure regularized by varying gravitational constant $G$. Then, we extend this idea onto the multiverse containing cyclic individual universes with either growing or decreasing entropy though leaving the net entropy constant. In order to get the key idea, we consider the doubleverse with the same geometrical evolution of the two "parallel" universes with their physical evolution (physical coupling constants $c(t)$ and $G(t)$) being different. An interesting point is that there is a possibility to exchange the universes at the point of maximum expansion -- the fact which was already noticed in quantum cosmology. Similar scenario is also possible within the framework of Brans-Dicke theory.
[Testicular torsion: A case report].
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.
Torsion Gravity for Dirac Fields
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.
An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy
Kalluri, Sreeramesh; Bonacuse, Peter J.
2010-01-01
Cumulative fatigue under axial and torsional loading conditions can include both load-order (higMow and low/high) as well as load-type sequence (axial/torsional and torsional/axial) effects. Previously reported experimental studies on a cobalt-base superalloy, Haynes 188 at 538 C, addressed these effects. These studies characterized the cumulative axial and torsional fatigue behavior under high amplitude followed by low amplitude (Kalluri, S. and Bonacuse, P. J., "Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequance Effects," in Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, S. Kalluri, and P. J. Bonacuse, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 281-301) and low amplitude followed by high amplitude (Bonacuse, P. and Kalluri, S. "Sequenced Axial and Torsional Cumulative Fatigue: Low Amplitude Followed by High Amplitude Loading," Biaxial/Multiaxial Fatigue and Fracture, ESIS Publication 31, A. Carpinteri, M. De Freitas, and A. Spagnoli, Eds., Elsevier, New York, 2003, pp. 165-182) conditions. In both studies, experiments with the following four load-type sequences were performed: (a) axial/axial, (b) torsional/torsional, (c) axial/torsional, and (d) torsional/axial. In this paper, the cumulative axial and torsional fatigue data generated in the two previous studies are combined to generate a comprehensive cumulative fatigue database on both the load-order and load-type sequence effects. This comprehensive database is used to examine applicability of the Palmgren-langer-Miner linear damage rule and a nonlinear damage curve approach for Haynes 188 subjected to the load-order and load-type sequencing described above. Summations of life fractions from the experiments are compared to the predictions from both the linear and nonlinear cumulative fatigue damage approaches. The significance of load-order versus load-type sequence effects for axial and torsional loading conditions
Repetitive maladaptive behavior: beyond repetition compulsion.
Bowins, Brad
2010-09-01
Maladaptive behavior that repeats, typically known as repetition compulsion, is one of the primary reasons that people seek psychotherapy. However, even with psychotherapeutic advances it continues to be extremely difficult to treat. Despite wishes and efforts to the contrary repetition compulsion does not actually achieve mastery, as evidenced by the problem rarely resolving without therapeutic intervention, and the difficulty involved in producing treatment gains. A new framework is proposed, whereby such behavior is divided into behavior of non-traumatic origin and traumatic origin with some overlap occurring. Repetitive maladaptive behavior of non-traumatic origin arises from an evolutionary-based process whereby patterns of behavior frequently displayed by caregivers and compatible with a child's temperament are acquired and repeated. It has a familiarity and ego-syntonic aspect that strongly motivates the person to retain the behavior. Repetitive maladaptive behavior of traumatic origin is characterized by defensive dissociation of the cognitive and emotional components of trauma, making it very difficult for the person to integrate the experience. The strong resistance of repetitive maladaptive behavior to change is based on the influence of both types on personality, and also factors specific to each. Psychotherapy, although very challenging at the best of times, can achieve the mastery wished and strived for, with the aid of several suggestions provided.
DEFF Research Database (Denmark)
Halse, Sven
2014-01-01
an enthusiastic worshipping of life, one that holds youth, health, strength and beauty as its primary attributes, and which was prevalent in all aspects of cultural life around 1900. But even the post war founders of the Vitalist re-conceptualisation of this era, Wolfdietrich Rasch and Gunter Martens, warned...... that also encompasses notions of destruction, decay and death. “All life symbols in literature around 1900 are at the same time symbols of death”. (Rasch, W. 1967:24) Through the analyses of three poems, this article aims to show concrete examples of how cyclic Vitalist thinking is embedded in poetry...
The torsional and rotation-torsion spectra of CD2HOH
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.
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.
Marosek, Konrad; Dąbrowski, Mariusz P.; Balcerzak, Adam
2016-09-01
Using the idea of regularization of singularities due to the variability of the fundamental constants in cosmology we study the cyclic universe models. We find two models of oscillating and non-singular mass density and pressure (`non-singular' bounce) regularized by varying gravitational constant G despite the scale factor evolution is oscillating and having sharp turning points (`singular' bounce). Both violating (big-bang) and non-violating (phantom) null energy condition models appear. Then, we extend this idea on to the multiverse containing cyclic individual universes with either growing or decreasing entropy though leaving the net entropy constant. In order to get an insight into the key idea, we consider the doubleverse with the same geometrical evolution of the two `parallel' universes with their physical evolution [physical coupling constants c(t) and G(t)] being different. An interesting point is that there is a possibility to exchange the universes at the point of maximum expansion - the fact which was already noticed in quantum cosmology. Similar scenario is also possible within the framework of Brans-Dicke theory where varying G(t) is replaced by the dynamical Brans-Dicke field φ(t) though these theories are slightly different.
Grammatical Change through Repetition.
Arevart, Supot
1989-01-01
The effect of repetition on grammatical change in an unrehearsed talk is examined based on a case study of a single learner. It was found that repetition allows for accuracy monitoring in that errors committed in repeated contexts undergo correction. Implications for teaching are discussed. (23 references) (LB)
The Negative Repetition Effect
Mulligan, Neil W.; Peterson, Daniel J.
2013-01-01
A fundamental property of human memory is that repetition enhances memory. Peterson and Mulligan (2012) recently documented a surprising "negative repetition effect," in which participants who studied a list of cue-target pairs twice recalled fewer targets than a group who studied the pairs only once. Words within a pair rhymed, and…
Energy Technology Data Exchange (ETDEWEB)
Bell, G.I.
1991-12-31
The DNA of higher eukaryotes contains many repetitive sequences. The study of repetitive sequences is important, not only because many have important biological function, but also because they provide information on genome organization, evolution and dynamics. In this paper, I will first discuss some generic effects that repetitive sequences will have upon genome dynamics and evolution. In particular, it will be shown that repetitive sequences foster recombination among, and turnover of, the elements of a genome. I will then consider some examples of repetitive sequences, notably minisatellite sequences and telomere sequences as examples of tandem repeats, without and with respectively known function, and Alu sequences as an example of interspersed repeats. Some other examples will also be considered in less detail.
Energy Technology Data Exchange (ETDEWEB)
Bell, G.I.
1991-12-31
The DNA of higher eukaryotes contains many repetitive sequences. The study of repetitive sequences is important, not only because many have important biological function, but also because they provide information on genome organization, evolution and dynamics. In this paper, I will first discuss some generic effects that repetitive sequences will have upon genome dynamics and evolution. In particular, it will be shown that repetitive sequences foster recombination among, and turnover of, the elements of a genome. I will then consider some examples of repetitive sequences, notably minisatellite sequences and telomere sequences as examples of tandem repeats, without and with respectively known function, and Alu sequences as an example of interspersed repeats. Some other examples will also be considered in less detail.
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...
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...
Relative entropy and torsion coupling
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.
Torsional Weyl-Dirac Electrodinamics
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...
Torsions of 3-dimensional manifolds
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
Topological design of torsional metamaterials
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.
DEFF Research Database (Denmark)
Halse, Sven
2014-01-01
of taking such a unilateral view of what constituted a Vitalist concept of life. It could lead to a misunderstanding of Vitalist way of thinking, Rasch said, if the focus were only set upon the enthusiastic surplus, the worshipping of youth and health. To Vitalists, life is more than that. It is a totality...... that also encompasses notions of destruction, decay and death. “All life symbols in literature around 1900 are at the same time symbols of death”. (Rasch, W. 1967:24) Through the analyses of three poems, this article aims to show concrete examples of how cyclic Vitalist thinking is embedded in poetry...... of the era. The analyses include a further sub-categorisation to capture the different types of Life Force dealt with in the texts. By way of an introduction, Vitalism is discussed within the context of the scientific and social developments of the 19th Century....
Wang, Yuhang; Nie, Jianguo; Fan, Jiansheng
2016-06-01
An experimental study on concrete filled steel tube columns with rectangular section subjected to compressionflexure-torsion combined action has been carried out. The failure modes and load-deformation hysteretic relations were obtained. Based on the principles of classical material mechanics, the relations between the torsion curvature of the section and the shear strain of the fiber on the section were established. Then the strain distribution on the rectangular section of concrete filled steel tube columns subjected to torsion was analyzed. The three-dimensional refined finite element model was also built, in order to make the precision verification. The matrix forms of the relation between the torsion curvature of the section and the shear strain of the fiber on the section were derived, and introduced into the fiber beam model considering nonlinear torsion effect on the section. The comparison between test results and calculation results showed that the fiber beam model considering nonlinear torsion effect had high modeling efficiency and solution precision for predicting the torsion behavior of concrete filled steel tube columns with rectangular sections, and was suitable for analyzing the dynamic response of various structures subjected to the combined cyclic load caused by the earthquake load.
Les torsions sur testicules cryptorchides
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
Repetition and Translation Shifts
Directory of Open Access Journals (Sweden)
Simon Zupan
2006-06-01
Full Text Available Repetition manifests itself in different ways and at different levels of the text. The first basic type of repetition involves complete recurrences; in which a particular textual feature repeats in its entirety. The second type involves partial recurrences; in which the second repetition of the same textual feature includes certain modifications to the first occurrence. In the article; repetitive patterns in Edgar Allan Poe’s short story “The Fall of the House of Usher” and its Slovene translation; “Konec Usherjeve hiše”; are compared. The author examines different kinds of repetitive patterns. Repetitions are compared at both the micro- and macrostructural levels. As detailed analyses have shown; considerable microstructural translation shifts occur in certain types of repetitive patterns. Since these are not only occasional; sporadic phenomena; but are of a relatively high frequency; they reduce the translated text’s potential for achieving some of the gothic effects. The macrostructural textual property particularly affected by these shifts is the narrator’s experience as described by the narrative; which suffers a reduction in intensity.
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.
Hidden torsion, 3-manifolds, and homology cobordism
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.
Cosmological Background torsion limits from Lorentz violation
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.
Trialogue: Preparation, Repetition and...
Oberg, Antoinette; And Others
1996-01-01
This paper interrogates both curriculum theory and the limits and potentials of textual forms. A set of overlapping discourses (a trialogue) focuses on inquiring into the roles of obsession and repetition in creating deeply interpretive locations for understanding. (SM)
Discrete Torsion and Symmetric Products
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.
Relative Entropy and Torsion Coupling
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.
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.
Type IIB orientifolds with discrete torsion
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.
Torsional optomechanics of a levitated nonspherical nanoparticle
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...
Torsion profiling of proteins using magnetic particles.
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.
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.
Optically probing torsional superelasticity in spider silks
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.
Statefinder diagnostic in a torsion cosmology
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.
Experimental Study on Cyclic Mechanics Characteristic of Saturated Soft Clay Strata
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Failure criterion of saturated soft clay is studied under cyclic loads through different experiments. A large number of cyclic torsional shear and cyclic triaxial tests on saturated soft clay under unconsolidated undrained condition are conducted. From the test result analysis, it is seen that the failure of saturated soft clay under static and cyclic loads satisfies Mises criterion. The result from different test stress states is not related to the test stress states or confining pressures. It can be applied in general stress states. Then according to the Mises criterion, the equivalent relationship on failure moment between the test stress state and the general stress state can be established. So the cyclic mechanics characteristics of saturated soft clay at failure moment are clarified in this paper. Furthermore, a theory basis is provided for using pseudo-static elasto-plastic cyclic strength model to evaluate cyclic bearing capacity.
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.
Random torsional vibration in automobile transmissions
Institute of Scientific and Technical Information of China (English)
无
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.
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.
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.)
Novel porcine repetitive elements
Directory of Open Access Journals (Sweden)
Nonneman Dan J
2006-12-01
Full Text Available Abstract Background Repetitive elements comprise ~45% of mammalian genomes and are increasingly known to impact genomic function by contributing to the genomic architecture, by direct regulation of gene expression and by affecting genomic size, diversity and evolution. The ubiquity and increasingly understood importance of repetitive elements contribute to the need to identify and annotate them. We set out to identify previously uncharacterized repetitive DNA in the porcine genome. Once found, we characterized the prevalence of these repeats in other mammals. Results We discovered 27 repetitive elements in 220 BACs covering 1% of the porcine genome (Comparative Vertebrate Sequencing Initiative; CVSI. These repeats varied in length from 55 to 1059 nucleotides. To estimate copy numbers, we went to an independent source of data, the BAC-end sequences (Wellcome Trust Sanger Institute, covering approximately 15% of the porcine genome. Copy numbers in BAC-ends were less than one hundred for 6 repeat elements, between 100 and 1000 for 16 and between 1,000 and 10,000 for 5. Several of the repeat elements were found in the bovine genome and we have identified two with orthologous sites, indicating that these elements were present in their common ancestor. None of the repeat elements were found in primate, rodent or dog genomes. We were unable to identify any of the replication machinery common to active transposable elements in these newly identified repeats. Conclusion The presence of both orthologous and non-orthologous sites indicates that some sites existed prior to speciation and some were generated later. The identification of low to moderate copy number repetitive DNA that is specific to artiodactyls will be critical in the assembly of livestock genomes and studies of comparative genomics.
Paulsen, Robert; Schwatka, Natalie; Gober, Jennifer; Gilkey, David; Anton, Dan; Gerr, Fred; Rosecrance, John
2014-01-01
This study evaluated the inter-rater reliability of the American Conference of Governmental Industrial Hygienists (ACGIH(®)) hand activity level (HAL), an observational ergonomic assessment method used to estimate physical exposure to repetitive exertions during task performance. Video recordings of 858 cyclic and non-cyclic appliance manufacturing tasks were assessed by sixteen pairs of raters using the HAL visual-analog scale. A weighted Pearson Product Moment-Correlation Coefficient was used to evaluate the agreement between the HAL scores recorded by each rater pair, and the mean weighted correlation coefficients for cyclic and non-cyclic tasks were calculated. Results indicated that the HAL is a reliable exposure assessment method for cyclic (r̄-bar w = 0.69) and non-cyclic work tasks (r̄-bar w = 0.68). When the two reliability scores were compared using a two-sample Student's t-test, no significant difference in reliability (p = 0.63) between these work task categories was found. This study demonstrated that the HAL may be a useful measure of exposure to repetitive exertions during cyclic and non-cyclic tasks.
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 ...
Analytic torsion versus Reidemeister torsion on hyperbolic 3-manifolds with cusps
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.
Axial-torsional fatigue: A study of tubular specimen thickness effects
Bonacuse, Peter J.; Kalluri, Sreeramesh
1990-01-01
A room-temperature experimental program was conducted on AISI type 316 stainless steel to determine the effect of wall thickness on the cyclic deformation behavior and fatigue life of thin-wall, tubular, axial-torsional fatigue specimens. The following experimental variables were examined in this study: the depth of the surface work-hardened layer produced in specimen machining, and the effects of strain range and axial-torsional strain phasing. Tubular fatigue specimens were fabricated with wall thicknesses of 1.5, 2.0, and 2.5 mm. One as-fabricated specimen from each wall thickness was sectioned for microstructural examination and microhardness measurement. A specimen of each wall thickness was tested at each of three conditions - high strain range in-phase, low strain range in-phase, and low strain range out-of-phase - for a total of nine axial-torsional fatigue experiments. The machining-induced work-hardened zone, as a percentage of the gage section material, was found to have a minimal effect on both deformation behavior and fatigue life. Also, little or no variation in fatigue life or deformation behavior as a function of wall thickness was observed. Out-of-phase fatigue tests displayed shorter fatigue lives and more cyclic hardening than in-phase tests.
Axial-torsional fatigue - A study of tubular specimen thickness effects
Bonacuse, Peter J.; Kalluri, Sreeramesh
1993-01-01
Experiments were carried out at room temperature on AISI type 316 stainless steel to determine the effect of wall thickness on the cyclic deformation behavior and fatigue life of thin-wall tubular axial-torsional fatigue specimens. The experimental variables examined included the depth of the surface work-hardened layer produced in specimen machining, and the effects of strain range and axial-torsional strain phasing. Tubular fatigue specimens had wall thicknesses of 1.5, 2.0, and 2.5 mm. One as-fabricated specimen from each wall thickness was sectioned for microstructural examination and microhardness measurement. A specimen of each wall thickness was tested in axial-torsional fatigue experiments for each of the three conditions: high strain range in-phase, low strain range in-phase, and low strain range out-of-phase. The machining-induced work-hardened zone, as a percentage of the gage section material, was found to have a minimal effect on both deformation behavior and fatigue life. Out-of-phase fatigue tests displayed shorter fatigue lives and more cyclic hardening than in-phase tests.
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.
Institute of Scientific and Technical Information of China (English)
无
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.
Dark Energy: Is It of Torsion Origin?
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.
Torsion and Supersymmetry in Omega-background
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.
Superconducting Cosmic String with Propagating Torsion
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.
Torsional fluctuations in columnar DNA assemblies
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...
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.
... or the flu eating certain foods, such as chocolate or cheese, or additives such as caffeine, nitrites— ... people with cyclic vomiting syndrome. Eating, Diet, and Nutrition During the prodrome and vomiting phases of cyclic ...
Superextensions of cyclic semigroups
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V. M. Gavrylkiv
2013-06-01
Full Text Available Given a cyclic semigroup $S$ we study right and left zeros,singleton left ideals, the minimal ideal, left cancelable andright cancelable elements of superextensions $lambda(S$ andcharacterize cyclic semigroups whose superextensions arecommutative.
Spin-torsion in Chaotic Inflation
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.
Case report of primary omental torsion
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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.
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.
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.
Centrifuge modelling of a laterally cyclic loaded pile
DEFF Research Database (Denmark)
Klinkvort, Rasmus Tofte; Leth, Caspar Thrane; Hededal, Ole
2010-01-01
A total number of 9 static and 6 cyclic centrifuge tests on laterally loaded piles in very dense, dry sand was erformed. The prototype dimensions of the piles were 1 meter in diameter and penetration depths varying from 6 to 10 meters. The static tests were used to investigate the initial subgrade...... reaction modulus and as a reference for cyclic tests. For the cyclic tests the accumulation of deflections and the change in secant stiffness of the soil from repetitive loading were investigated. From all the tests carried out accumulations of deflections were seen. rom the centrifuge tests it was seen...
Cyclic Railway Timetable Optimization
L.W.P. Peeters (Leon)
2003-01-01
textabstractCyclic Railway Timetable Optimization describes mathematical models and solution methods for constructing high quality cyclic railway timetables. In a cyclic timetable, a train for a certain destination leaves a certain station at the same time every cycle time, say every half an hour,
Torsional oscillations of strange stars
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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.
Cyclic stretch-bending: mechanics, stability and formability
Emmens, W.C.; van den Boogaard, Antonius H.
2011-01-01
Cyclic stretch-bending has been studied using the so-called Continuous-Bending-under-Tension (CBT) test. This is a modified tensile test where the specimen is subjected to repetitive bending at the same time. A wide variety of materials have been tested this way. A simple mechanical model is
Directory of Open Access Journals (Sweden)
R.Citarella
2015-01-01
Full Text Available An edge crack propagation in a steel bar of circular cross-section undergoing multiaxial fatigue loads is simulated by Finite Element Method (FEM. The variation of crack growth behaviour is studied under axial and combined in phase axial+torsional fatigue loading. Results show that the cyclic Mode III loading superimposed on the cyclic Mode I leads to a fatigue life reduction. Numerical calculations are performed using the FEM software ZENCRACK to determine the crack path and fatigue life. The FEM numerical predictions have been compared against corresponding experimental and numerical data, available from literature, getting satisfactory consistency.
MIMICRY, DIFFERENCE AND REPETITION
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Marcelo Mendes de Souza
2008-07-01
Full Text Available This article addresses Homi K. Bhabha’s concept of mimicry in a broader context, other than that of cultural studies and post-colonial studies, bringing together other concepts, such as that of Gilles Deleuze in Difference and repetition, among other texts, and other names, such as Silviano Santiago, Jorge Luís Borges, Franz Kafka and Giorgio Agamben. As a partial conclusion, the article intends to oppose Bhabha’s freudian-marxist view to Five propositions on Psychoanalysis (1973, Gilles Deleuze’s text about Psychoanalysis published right after his book The Anti-Oedipus.
Torsion-mediated interaction between adjacent genes.
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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.
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....
Metric-torsion preheating: cosmic dynamo mechanism?
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...
Carbon nanotube torsional springs for regenerative braking systems
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.
Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves
Energy Technology Data Exchange (ETDEWEB)
Somogyi, D.; Alvarez, P.D.; Kalsi, M.S. [Kalsi Engineering, Inc., Sugar Land, TX (United States)
1996-12-01
Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the {open_quote}Thrust Rating Increase{close_quote} test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner`s rule. Model predictions were validated against actual cyclic loading test results.
Active structures to reduce torsional vibrations
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.
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....
Cyclic phosphonium ionic liquids
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Sharon I. Lall-Ramnarine
2014-01-01
Full Text Available Ionic liquids (ILs incorporating cyclic phosphonium cations are a novel category of materials. We report here on the synthesis and characterization of four new cyclic phosphonium bis(trifluoromethylsulfonylamide ILs with aliphatic and aromatic pendant groups. In addition to the syntheses of these novel materials, we report on a comparison of their properties with their ammonium congeners. These exemplars are slightly less conductive and have slightly smaller self-diffusion coefficients than their cyclic ammonium congeners.
Torsional wave propagation in solar tornadoes
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.
Clinical variants of idiopathic torsion dystonia.
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.
Ventricular torsional relation to ventricular fiber arrangement
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.
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...
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].
Torsion theories of pseudo-regular S-systems
Institute of Scientific and Technical Information of China (English)
无
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.
Yang, Jing-Fang; Wu, Tao; Li, Jian-Yu; Li, Yong-Jie; Zhang, Yan-Li; Chan, Piu
2009-01-30
Torsion dystonia is an autosomal dominant movement disorder characterized by involuntary, repetitive muscle contractions and twisted postures. The most severe early onset form of dystonia has been linked to mutations in the human DYT1 (TOR1A) gene encoding a protein termed torsinA. Moreover, dystonia and Parkinson disease share the common feature of reduced dopamine neurotransmission in the striatum, so we assumed that mutations in the DYT1 gene might have the same role in cases of early onset primary torsion dystonia (EOPTD) and early onset Parkinson disease (EOPD) that present dystonia. In this present study, 17 patients with EOPTD, 221 patients with EOPD and 164 control subjects were screened for mutations of the DYT1 gene by denaturing high performance liquid chromatography (DHPLC), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and DNA sequencing. Our results showed that the GAG deletion was identified in 7 EOPTD patients, which results in Glu302del of DYT1 gene. No mutations were found in EOPD patients and control subjects. By carefully reviewing the available literature on studies of sporadic, non-Ashkenazi Jewish populations, the results showed that the prevalence rate of DYT1 mutation was not significantly different (p=0.267) between European (27.3%) and Asian (22.2%) patients with early onset primary torsion dystonia.
Stewart, Greg; Kuntzleman, Thomas S.; Amend, John R.; Collins, Michael J.
2009-01-01
Cyclic voltammetry is an important component of the undergraduate chemical curriculum. Unfortunately, undergraduate students rarely have the opportunity to conduct experiments in cyclic voltammetry owing to the high cost of potentiostats, which are required to control these experiments. By using MicroLab data acquisition interfaces in conjunction…
Stewart, Greg; Kuntzleman, Thomas S.; Amend, John R.; Collins, Michael J.
2009-01-01
Cyclic voltammetry is an important component of the undergraduate chemical curriculum. Unfortunately, undergraduate students rarely have the opportunity to conduct experiments in cyclic voltammetry owing to the high cost of potentiostats, which are required to control these experiments. By using MicroLab data acquisition interfaces in conjunction…
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.
Torsion of the gallbladder: a case report
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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.
Test particle acceleration in torsional fan reconnection
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.
Plant-based torsional actuator with memory
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 kg1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-...
Symmetric products, permutation orbifolds and discrete torsion
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.
Understanding maximal repetitions in strings
Crochemore, Maxime
2008-01-01
The cornerstone of any algorithm computing all repetitions in a string of length n in O(n) time is the fact that the number of runs (or maximal repetitions) is O(n). We give a simple proof of this result. As a consequence of our approach, the stronger result concerning the linearity of the sum of exponents of all runs follows easily.
Ijjas, Anna
2016-01-01
Cyclic models of the universe have the advantage of avoiding initial conditions problems related to postulating any sort of beginning in time. To date, the only known viable examples of cyclic models have been ekpyrotic. In this paper, we show that the recently proposed anamorphic scenario can also be made cyclic. The key to the cyclic completion is a classically stable, non-singular bounce. Remarkably, even though the bounce construction was originally developed to connect a period of contraction with a period of expansion both described by Einstein gravity, we show here that it can naturally be modified to connect an ordinary contracting phase described by Einstein gravity with a phase of anamorphic smoothing. The paper will present the basic principles and steps in constructing cyclic anamorphic models.
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.
Perceptual Repetition Blindness Effects
Hochhaus, Larry; Johnston, James C.; Null, Cynthia H. (Technical Monitor)
1994-01-01
The phenomenon of repetition blindness (RB) may reveal a new limitation on human perceptual processing. Recently, however, researchers have attributed RB to post-perceptual processes such as memory retrieval and/or reporting biases. The standard rapid serial visual presentation (RSVP) paradigm used in most RB studies is, indeed, open to such objections. Here we investigate RB using a "single-frame" paradigm introduced by Johnston and Hale (1984) in which memory demands are minimal. Subjects made only a single judgement about whether one masked target word was the same or different than a post-target probe. Confidence ratings permitted use of signal detection methods to assess sensitivity and bias effects. In the critical condition for RB a precue of the post-target word was provided prior to the target stimulus (identity precue), so that the required judgement amounted to whether the target did or did not repeat the precue word. In control treatments, the precue was either an unrelated word or a dummy.
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.
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.
Directory of Open Access Journals (Sweden)
Chenchen Jiang
2016-03-01
Full Text Available Fatigue behavior of nanomaterials could ultimately limit their applications in variable nano-devices and flexible nanoelectronics. However, very few existing nanoscale mechanical testing instruments were designed for dedicated fatigue experiments, especially for the challenging torsional cyclic loading. In this work, a novel high-cycle torsion straining micromachine, based on the digital micromirror device (DMD, has been developed for the torsional fatigue study on various one-dimensional (1D nanostructures, such as metallic and semiconductor nanowires. Due to the small footprint of the DMD chip itself and its cable-remote controlling mechanisms, it can be further used for the desired in situ testing under high-resolution optical or electron microscopes (e.g., scanning electron microscope (SEM, which allows real-time monitoring of the fatigue testing status and construction of useful structure-property relationships for the nanomaterials. We have then demonstrated its applications for testing nanowire samples with diameters about 100 nm and 500 nm, up to 1000 nm, and some of them experienced over hundreds of thousands of loading cycles before fatigue failure. Due to the commercial availability of the DMD and millions of micromirrors available on a single chip, this platform could offer a low-cost and high-throughput nanomechanical solution for the uncovered torsional fatigue behavior of various 1D nanostructures.
Real Topological Cyclic Homology
DEFF Research Database (Denmark)
Høgenhaven, Amalie
The main topics of this thesis are real topological Hochschild homology and real topological cyclic homology. If a ring or a ring spectrum is equipped with an anti-involution, then it induces additional structure on the topological Hochschild homology spectrum. The group O(2) acts on the spectrum......, where O(2) is the semi-direct product of T, the multiplicative group of complex number of modulus 1, by the group G=Gal(C/R). We refer to this O(2)-spectrum as the real topological Hochschild homology. This generalization leads to a G-equivariant version of topological cyclic homology, which we call...... real topological cyclic homology. The first part of the thesis computes the G-equivariant homotopy type of the real topological cyclic homology of spherical group rings at a prime p with anti-involution induced by taking inverses in the group. The second part of the thesis investigates the derived G...
Cup products in Hopf cyclic cohomology via cyclic modules I
Rangipour, Bahram
2007-01-01
This is the first one in a series of two papers on the continuation of our study in cup products in Hopf cyclic cohomology. In this note we construct cyclic cocycles of algebras out of Hopf cyclic cocycles of algebras and coalgebras. In the next paper we consider producing Hopf cyclic cocycle from "equivariant" Hopf cyclic cocycles. Our approach in both situations is based on (co)cyclic modules and bi(co)cyclic modules together with Eilenberg-Zilber theorem which is different from the old definition of cup products defined via traces and cotraces on DG algebras and coalgebras.
Roland, Christopher D.; Li, Hong; Abboud, Khalil A.; Wagener, Kenneth B.; Veige, Adam S.
2016-08-01
Cyclic polymers have dramatically different physical properties compared with those of their equivalent linear counterparts. However, the exploration of cyclic polymers is limited because of the inherent challenges associated with their synthesis. Conjugated linear polyacetylenes are important materials for electrical conductivity, paramagnetic susceptibility, optical nonlinearity, photoconductivity, gas permeability, liquid crystallinity and chain helicity. However, their cyclic analogues are unknown, and therefore the ability to examine how a cyclic topology influences their properties is currently not possible. We have solved this challenge and now report a tungsten catalyst supported by a tetraanionic pincer ligand that can rapidly polymerize alkynes to form conjugated macrocycles in high yield. The catalyst works by tethering the ends of the polymer to the metal centre to overcome the inherent entropic penalty of cyclization. Gel-permeation chromatography, dynamic and static light scattering, viscometry and chemical tests are all consistent with theoretical predictions and provide unambiguous confirmation of a cyclic topology. Access to a wide variety of new cyclic polymers is now possible by simply choosing the appropriate alkyne monomer.
Investigation of the torsional stiffness of flexible disc coupling
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.
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.
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.)
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.
Electrostatically actuated torsional resonant sensors and switches
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.
Is Torsion a Fundamental Physical Field?
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.
Gravitomagnetic effect and spin-torsion coupling
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.
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.
REDUCTION APPROACHES FOR VIBRATION CONTROL OF REPETITIVE STRUCTURES
Institute of Scientific and Technical Information of China (English)
CHEN Wei-min; SUN Dong-chang; WANG Da-jun; WEI Jian-ping; TONG Li-yong; WANG Quan
2006-01-01
The reduction approaches are presented for vibration control of symmetric,cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced.
Biothermal sensing of a torsional artificial muscle
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
Design of a nonlinear torsional vibration absorber
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
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
Analytic Torsion of Z_2-graded Elliptic Complexes
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.
Torsional Alfven waves in stratified and expanding magnetic flux tubes
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.
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.
Directory of Open Access Journals (Sweden)
Charles C. F. Kwan
2012-02-01
Full Text Available A deeper understanding of the mechanical behavior of ultra-fine (UF and nanocrystalline (NC grained metals is necessary with the growing interest in using UF and NC grained metals for structural applications. The cyclic deformation response and behavior of UF and NC grained metals is one aspect that has been gaining momentum as a major research topic for the past ten years. Severe Plastic Deformation (SPD materials are often in the spotlight for cyclic deformation studies as they are usually in the form of bulk work pieces and have UF and NC grains. Some well known techniques in the category of SPD processing are High Pressure Torsion (HPT, Equal Channel Angular Pressing (ECAP, and Accumulative Roll-Bonding (ARB. In this report, the literature on the cyclic deformation response and behavior of SPDed metals will be reviewed. The cyclic response of such materials is found to range from cyclic hardening to cyclic softening depending on various factors. Specifically, for SPDed UF grained metals, their behavior has often been associated with the observation of grain coarsening during cycling. Consequently, the many factors that affect the cyclic deformation response of SPDed metals can be summarized into three major aspects: (1 the microstructure stability; (2 the limitation of the cyclic lifespan; and lastly (3 the imposed plastic strain amplitude.
Repetition in English Political Public Speaking
Institute of Scientific and Technical Information of China (English)
李红梅
2010-01-01
Repetition is frequently used in English political public speaking to make it easy to be remembered and powerful to move the feelings of the public. This paper is intended to analyze the functions of repetition and different levels of repetition to highlight the significance of repetition in English political public speaking and the ability of using it in practice.
Constraining Torsion in Maximally symmetric (sub)spaces
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.
Alpha surfaces for complex space-times with torsion
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.
Isolated Penile Torsion in Brothers: A Case Report
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...
Association of Torsion With Testicular Cancer: A Retrospective Study.
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
Torsional Newton-Cartan geometry from Galilean gauge theory
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.
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.
Generalized Wideband Cyclic MUSIC
Directory of Open Access Journals (Sweden)
Zhang-Meng Liu
2009-01-01
Full Text Available The method of Spectral Correlation-Signal Subspace Fitting (SC-SSF fails to separate wideband cyclostationary signals with coherent second-order cyclic statistics (SOCS. Averaged Cyclic MUSIC (ACM method made up for the drawback to some degree via temporally averaging the cyclic cross-correlation of the array output. This paper interprets ACM from another perspective and proposes a new DOA estimation method by generalizing ACM for wideband cyclostationary signals. The proposed method successfully makes up for the aforementioned drawback of SC-SSF and obtains a more satisfying performance than ACM. It is also demonstrated that ACM is a simplified form of the proposed method when only a single spectral frequency is exploited, and the integration of the frequencies within the signal bandwidth helps the new method to outperform ACM.
The cyclic reduction algorithm
Bini, Dario; Meini, Beatrice
2009-05-01
Cyclic reduction is an algorithm invented by G.H. Golub and R. W. Hockney in the mid 1960s for solving linear systems related to the finite differences discretization of the Poisson equation over a rectangle. Among the algorithms of Gene Golub, it is one of the most versatile and powerful ever created. Recently, it has been applied to solve different problems from different applicative areas. In this paper we survey the main features of cyclic reduction, relate it to properties of analytic functions, recall its extension to solving more general finite and infinite linear systems, and different kinds of nonlinear matrix equations, including algebraic Riccati equations, with applications to Markov chains, queueing models and transport theory. Some new results concerning the convergence properties of cyclic reduction and its applicability are proved under very weak assumptions. New formulae for overcoming breakdown are provided.
Varianish: Jamming with Pattern Repetition
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Jort Band
2014-10-01
Full Text Available In music, patterns and pattern repetition are often regarded as a machine-like task, indeed often delegated to drum Machines and sequencers. Nevertheless, human players add subtle differences and variations to repeated patterns that are musically interesting and often unique. Especially when looking at minimal music, pattern repetitions create hypnotic effects and the human mind blends out the actual pattern to focus on variation and tiny differences over time. Varianish is a musical instrument that aims at turning this phenomenon into a new musical experience for musician and audience: Musical pattern repetitions are found in live music and Varianish generates additional (musical output accordingly that adds substantially to the overall musical expression. Apart from the theory behind the pattern finding and matching and the conceptual design, a demonstrator implementation of Varianish is presented and evaluated.
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.
REPETITIVE CLUSTER-TILTED ALGEBRAS
Institute of Scientific and Technical Information of China (English)
Zhang Shunhua; Zhang Yuehui
2012-01-01
Let H be a finite-dimensional hereditary algebra over an algebraically closed field k and CFm be the repetitive cluster category of H with m ≥ 1.We investigate the properties of cluster tilting objects in CFm and the structure of repetitive clustertilted algebras.Moreover,we generalize Theorem 4.2 in [12](Buan A,Marsh R,Reiten I.Cluster-tilted algebra,Trans.Amer.Math.Soc.,359(1)(2007),323-332.) to the situation of CFm,and prove that the tilting graph KCFm of CFm is connected.
Search for torsional oscillations in isolated sunspots
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.
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.
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.
Interaction Effects of Simultaneous Torsional and Compressional Cyclic Loading of Sand.
1979-12-01
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... digestive diseases specialist (gastroenterologist). If you or your child is in the middle of a severe vomiting episode, the doctor may ... system disorders There's no cure for cyclic vomiting syndrome, so treatment ... may be prescribed: Anti-nausea drugs Sedatives Medications ...
Cyclic Voltammetry Experiment.
Van Benschoten, James J.; And Others
1983-01-01
Describes a three-part experiment designed to introduce cyclic voltammetry to graduate/undergraduate students. Part 1 demonstrates formal reduction potential, redox electron transfer, diffusion coefficient, and electrochemical reversibility. Part 2 investigates electrochemical behavior of acetaminophen. Part 3 examines such experimental variables…
Wu, Yingquan
2008-01-01
The paper has a threefold purpose. The first purpose is to present an explicit description of expanded cyclic codes defined in $\\GF(q^m)$. The proposed explicit construction of expanded generator matrix and expanded parity check matrix maintains the symbol-wise algebraic structure and thus keeps many important original characteristics. The second purpose of this paper is to identify a class of constant-weight cyclic codes. Specifically, we show that a well-known class of $q$-ary BCH codes excluding the all-zero codeword are constant-weight cyclic codes. Moreover, we show this class of codes achieve the Plotkin bound. The last purpose of the paper is to characterize expanded cyclic codes utilizing the proposed expanded generator matrix and parity check matrix. We analyze the properties of component codewords of a codeword and particularly establish the precise conditions under which a codeword can be represented by a subbasis. With the new insights, we present an improved lower bound on the minimum distance of...
Cyclic Voltammetry Experiment.
Van Benschoten, James J.; And Others
1983-01-01
Describes a three-part experiment designed to introduce cyclic voltammetry to graduate/undergraduate students. Part 1 demonstrates formal reduction potential, redox electron transfer, diffusion coefficient, and electrochemical reversibility. Part 2 investigates electrochemical behavior of acetaminophen. Part 3 examines such experimental variables…
Constraints on torsion from bounds on lorentz violation.
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.
Hydrostatic self-aligning axial/torsional mechanism
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.
Mechanical origins of rightward torsion in early chick brain development
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.
Torsional Strengthening of RC Beams Using GFRP Composites
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.
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.
Repetitive elements in parasitic protozoa
Directory of Open Access Journals (Sweden)
Clayton Christine
2010-05-01
Full Text Available Abstract A recent paper published in BMC Genomics suggests that retrotransposition may be active in the human gut parasite Entamoeba histolytica. This adds to our knowledge of the various types of repetitive elements in parasitic protists and the potential influence of such elements on pathogenicity. See research article http://www.biomedcentral.com/1471-2164/11/321
The Reidemeister torsion of 3-manifolds
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 ...
Torsion angle preferences in druglike chemical space: a comprehensive guide.
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.
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.
Torsion and accelerating expansion of the universe in quadratic gravitation
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...
Torsional and rotational coupling in non-rigid molecules
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.
Peculiar torsion dynamical response of spider dragline silk
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.
Cosmological background torsion inhomogeneities and Lorentz violation in QED
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.
Cyclic Voltammograms from First Principles
DEFF Research Database (Denmark)
Karlberg, Gustav; Jaramillo, Thomas; Skulason, Egill
2007-01-01
Cyclic voltammetry is a fundamental experimental tool for characterizing electrochemical surfaces. Whereas cyclic voltammetry is widely used within the field of electrochemistry, a way to quantitatively and directly relate the cyclic voltammogram to ab initio calculations has been lacking, even f...
A study of white etching crack formation by compression-torsion experiments
Directory of Open Access Journals (Sweden)
S. Averbeck
2016-10-01
Full Text Available In this study, an attempt was made to recreate the bearing damage phenomenon “White Etching Cracks” with a simplified testing setup. Rolling contact fatigue conditions were simulated with in-phase and out-ofphase cyclic compression-torsion experiments on 100Cr6 steel specimens. The results are compared in terms of microstructural change. Focused Ion Beam and metallographic analysis reveal that a fine-grained, white etching zone formed in the vicinity of the fatigue cracks of specimens tested with the in-phase load pattern. In contrast, no such structures were found after testing the out-of-phase load pattern. The properties of the white etching zone are characterised in more detail and compared with White Etching Cracks
Repetition suppression and repetition priming are processing outcomes.
Wig, Gagan S
2012-01-01
Abstract There is considerable evidence that repetition suppression (RS) is a cortical signature of previous exposure to the environment. In many instances RS in specific brain regions is accompanied by improvements in specific behavioral measures; both observations are outcomes of repeated processing. In understanding the mechanism by which brain changes give rise to behavioral changes, it is important to consider what aspect of the environment a given brain area or set of areas processes, and how this might be expressed behaviorally.
Vulfson, Iosif
2015-01-01
This book focuses on modern methods of oscillation analysis in machines, including cyclic action mechanisms (linkages, cams, steppers, etc.). It presents schematization techniques and mathematical descriptions of oscillating systems, taking into account the variability of the parameters and nonlinearities, engineering evaluations of dynamic errors, and oscillation suppression methods. The majority of the book is devoted to the development of new methods of dynamic analysis and synthesis for cyclic machines that form regular oscillatory systems with multiple duplicate modules. There are also sections examining aspects of general engineering interest (nonlinear dissipative forces, systems with non-stationary constraints, impacts and pseudo-impacts in clearances, etc.) The examples in the book are based on the widely used results of theoretical and experimental studies as well as engineering calculations carried out in relation to machines used in the textile, light, polygraphic and other industries. Particu...
Steinhardt, P J; Steinhardt, Paul J.; Turok, Neil
2004-01-01
The Cyclic Model attempts to resolve the homogeneity, isotropy, and flatness problems and generate a nearly scale-invariant spectrum of fluctuations during a period of slow contraction that precedes a bounce to an expanding phase. Here we describe at a conceptual level the recent developments that have greatly simplified our understanding of the contraction phase and the Cyclic Model overall. The answers to many past questions and criticisms are now understood. In particular, we show that the contraction phase has equation of state w>1 and that contraction with w>1 has a surprisingly similar properties to inflation with w < -1/3. At one stroke, this shows how the model is different from inflation and why it may work just as well as inflation in resolving cosmological problems.
Modelling the torsion of thin metal wires by distortion gradient plasticity
Bardella, Lorenzo; Panteghini, Andrea
2015-05-01
Under small strains and rotations, we apply a phenomenological higher-order theory of distortion gradient plasticity to the torsion problem, here assumed as a paradigmatic benchmark of small-scale plasticity. Peculiar of the studied theory, proposed about ten years ago by Morton E. Gurtin, is the constitutive inclusion of the plastic spin, affecting both the free energy and the dissipation. In particular, the part of the free energy, called the defect energy, which accounts for Geometrically Necessary Dislocations, is a function of Nye's dislocation density tensor, dependent on the plastic distortion, including the plastic spin. For the specific torsion problem, we implement this distortion gradient plasticity theory into a Finite Element (FE) code characterised by implicit (Backward Euler) time integration, numerically robust and accurate for both viscoplastic and rate-independent material responses. We show that, contrariwise to other higher-order theories of strain gradient plasticity (neglecting the plastic spin), the distortion gradient plasticity can predict some strengthening even if a quadratic defect energy is chosen. On the basis of the results of many FE analyses, concerned with (i) cyclic loading, (ii) switch in the higher-order boundary conditions during monotonic plastic loading, (iii) the use of non-quadratic defect energies, and (iv) the prediction of experimental data, we mainly show that (a) including the plastic spin contribution in a gradient plasticity theory is highly recommendable to model small-scale plasticity, (b) less-than-quadratic defect energies may help in describing the experimental results, but they may lead to anomalous cyclic behaviour, and (c) dissipative (unrecoverable) higher-order finite stresses are responsible for an unexpected mechanical response under non-proportional loading.
Directory of Open Access Journals (Sweden)
J Gordon Millichap
2002-12-01
Full Text Available In a study at Children’s Hospital, Ann Arbor, MI, and Children’s Memorial Hospital, Chicago, designed primarily to compare cost-effectiveness of three methods of management of cyclic vomiting cases, one group of patients received an extensive diagnostic evaluation, a second was treated with empiric antimigraine drugs for 2 months, and a third an upper GI series with small-bowel follow-through (UGI-SBFT plus empiric therapy.
2009-12-18
analysis of the equilibria based on linearization of the shape dynamics. In [10], the authors extend their analysis to incorporate feedback control...differentiable curves in R2, deriving our dynamics from the natural Frenet frame equations (see, e.g., [5] for details). (A three- dimensional analysis of...cyclic pursuit formulated in terms of the natural Frenet frame equations is a topic of ongoing work.) As is depicted in figure 1, we let ri denote the
Cohesive Function of Lexical Repetition in Text
Institute of Scientific and Technical Information of China (English)
张莉; 卢沛沛
2013-01-01
Lexical repetition is the most direct form of lexical cohesion,which is the central device for making texts hang together. Although repetition is the most direct way to emphasize,it performs the cohesive effect more apparently.
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.
Torsion-free Sheaves and ACM Schemes
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.$
Torsional oscillations of nonbare strange stars
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...
Torsion based universal MEMS logic device
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.
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.
Plant-based torsional actuator with memory
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.
Doxorubicin, DNA torsion, and chromatin dynamics
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
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.
[Torsion and necrosis of epiploic appendices of the large bowel].
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.
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.
Torsion of a wandering spleen: an unusual abdominal catastrophe.
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.
Gravitational Geometric Phase in the Presence of Torsion
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.
5D Lovelock gravity: new exact solutions with torsion
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.
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.
Random gust response statistics for coupled torsion-flapping rotor blade vibrations.
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.
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...
The dynamics and excitation of torsional waves in geodynamo simulations
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...
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
Torsional dynamics of steerable needles: modeling and fluoroscopic guidance.
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.
Behavior of the SU(2)-Reidemeister torsion form by mutation
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.
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.
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.
Isolated adnexal torsion in a 20-week spontaneous twin pregnancy
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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.
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.
Two-step spacetime deformation induced dynamical torsion
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.
Effect of tensile and torsion on GMI in amorphous wire
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.
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.
Quantization of Two-Dimensional Gravity with Dynamical Torsion
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.
M-theory moduli spaces and torsion-free structures
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.
M-theory moduli spaces and torsion-free structures
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.
Diffusion-weighted imaging findings of adnexal torsion: Initial results
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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.
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.
Ekpyrotic and Cyclic Cosmology
Lehners, Jean-Luc
2008-01-01
Ekpyrotic and cyclic cosmologies provide theories of the very early and of the very late universe. In these models, the big bang is described as a collision of branes - and thus the big bang is not the beginning of time. Before the big bang, there is an ekpyrotic phase with equation of state w=P/rho >> 1 (where P is the average pressure and rho the average energy density) during which the universe slowly contracts. This phase resolves the standard cosmological puzzles and generates a nearly scale-invariant spectrum of cosmological perturbations containing a significant non-gaussian component. At the same time it produces small-amplitude gravitational waves with a blue spectrum. The dark energy dominating the present-day cosmological evolution is reinterpreted as a small attractive force between our brane and a parallel one. This force eventually induces a new ekpyrotic phase and a new brane collision, leading to the idea of a cyclic universe. This review discusses the detailed properties of these models, thei...
Ekpyrotic and cyclic cosmology
Energy Technology Data Exchange (ETDEWEB)
Lehners, Jean-Luc [Princeton Center for Theoretical Science, Jadwin Hall, Princeton University, Princeton NJ 08544 (United States)], E-mail: jlehners@princeton.edu
2008-09-15
Ekpyrotic and cyclic cosmologies provide theories of the very early and of the very late universe. In these models, the big bang is described as a collision of branes - and thus the big bang is not the beginning of time. Before the big bang, there is an ekpyrotic phase with equation of state w=P/({rho}) >>1 (where P is the average pressure and {rho} the average energy density) during which the universe slowly contracts. This phase resolves the standard cosmological puzzles and generates a nearly scale-invariant spectrum of cosmological perturbations containing a significant non-Gaussian component. At the same time it produces small-amplitude gravitational waves with a blue spectrum. The dark energy dominating the present-day cosmological evolution is reinterpreted as a small attractive force between our brane and a parallel one. This force eventually induces a new ekpyrotic phase and a new brane collision, leading to the idea of a cyclic universe. This review discusses the detailed properties of these models, their embedding in M-theory and their viability, with an emphasis on open issues and observational signatures.
[Asthma and cyclic neutropenia].
Salazar Cabrera, A N; Berrón Pérez, R; Ortega Martell, J A; Onuma Takane, E
1996-01-01
We report a male with history of recurrent infections (recurrent oral aphtous disease [ROAD], middle ear infections and pharyngo amigdalitis) every 3 weeks since he was 7 months old. At the age of 3 years cyclic neutropenia was diagnosed with cyclic fall in the total neutrophil count in blood smear every 21 days and prophylactic antimicrobial therapy was indicated. Episodic events every 3 weeks of acute asthma and allergic rhinitis were detected at the age of 6 years old and specific immunotherapy to Bermuda grass was given during 3 years with markedly improvement in his allergic condition but not in the ROAD. He came back until the age of 16 with episodic acute asthma and ROAD. The total neutrophil count failed to 0 every 21 days and surprisingly the total eosinophil count increased up to 2,000 at the same time, with elevation of serum IgE (412 Ul/mL). Specific immunotherapy to D.pt. and Aller.a. and therapy with timomodulin was indicated. After 3 months we observed clinical improvement in the asthmatic condition and the ROAD disappeared, but the total neutrophil count did not improve. We present this case as a rare association between 2 diseases with probably no etiological relationship but may be physiopatological that could help to understand more the pathogenesis of asthma.
Considerations on the Sp\\"orer-diagram - torsional wave relationship
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.
Anomalous pressure dependence of the torsional levels in solid nitromethane
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.
Abnormalities of Penile Curvature: Chordee and Penile Torsion
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 ...
Torsion Points on an Algebraic Subset of an Affine Torus
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.
Muscular Basis of Whisker Torsion in Mice and Rats.
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.
A Numerical Model for Torsion Analysis of Composite Ship Hulls
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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.
Circuit considerations for repetitive railguns
Energy Technology Data Exchange (ETDEWEB)
Honih, E.M.
1986-01-01
Railgun electromagnetic launchers have significant military and scientific potential. They provide direct conversion of electrical energy to projectile kinetic energy, and they offer the hope of achieving projectile velocities greatly exceeding the limits of conventional guns. With over 10 km/sec already demonstrated, railguns are attracting attention for tactical and strategic weapons systems and for scientific equation-of-state research. The full utilization of railguns will require significant improvements in every aspect of system design - projectile, barrel, and power source - to achieve operation on a large scale. This paper will review fundamental aspects of railguns, with emphasis on circuit considerations and repetitive operation.
Exciton Localization in Extended {\\pi}-electron Systems: Comparison of Linear and Cyclic Structures
Thiessen, Alexander; Jester, Stefan-S; Aggarwal, A Vikas; Idelson, Alissa; Bange, Sebastian; Vogelsang, Jan; Höger, Sigurd; Lupton, John M
2015-01-01
We employ five {\\pi}-conjugated model materials of different molecular shape --- oligomers and cyclic structures --- to investigate the extent of exciton self-trapping and torsional motion of the molecular framework following optical excitation. Our studies combine steady-state and transient fluorescence spectroscopy in the ensemble with measurements of polarization anisotropy on single molecules, supported by Monte Carlo simulations. The dimer exhibits a significant spectral red-shift within $\\sim$ 100 ps after photoexcitation which is attributed to torsional relaxation. This relaxation mechanism is inhibited in the structurally rigid macrocyclic analogue. However, both systems show a high degree of exciton localization but with very different consequences: while in the macrocycle the exciton localizes randomly on different parts of the ring, scrambling polarization memory, in the dimer, localization leads to a deterministic exciton position with luminescence characteristics of a dipole. Monte Carlo simulati...
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.
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.
Thermal conductivity and torsional oscillations of solid 4He
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.
Torsion as a Dark Matter Candidate from the Higgs Portal
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...
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
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.
Fragmentations of protonated cyclic-glycylglycine and cyclic-alanylalanine
Shek, P. Y. I.; Lau, J. K. C.; Zhao, J. F.; Grzetic, J.; Verkerk, U. H.; Oomens, J.; Hopkinson, A. C.; Siu, K. W. M.
2012-01-01
Collision-induced dissociation has been used to study the fragmentations of two protonated diketopiperazines, protonated cyclic-glycylglycine and cyclic-alanylalanine. Protonated cyclo-AA lost CO and (CO + NH3) at low collision energies, channels attributed to dissociation of the O-protonated
The protective role of erdosteine on testicular tissue after testicular torsion and detorsion.
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
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)
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.
Strategies for low detection limit measurements with cyclic voltammetry.
Wiedemann, D J; Kawagoe, K T; Kennedy, R T; Ciolkowski, E L; Wightman, R M
1991-12-15
Cyclic voltammetry of Nafion-coated, carbon-fiber electrodes is used to detect trace concentrations of dopamine, both in a flow injection apparatus and in the brain of an anaesthetized rat. To improve signal-to-noise ratios, the sources of noise during cyclic voltammetry have been determined and strategies have been developed to decrease the noise. With the potentiostat employed, the measured noise is comparable to that expected for Johnson noise from the feedback resistor of the current transducer. Additional noise arises from the waveform generator employed and, in some cases, line noise. Line noise is discriminated against by starting each cyclic voltammogram either in phase or 180 degrees out of phase with the line frequency. When used in vivo, additional noise also arises from the physiological activity of the animal. Detection limits are found to closely correspond to those predicted on the basis of simulation of the voltammetric shape and the measured noise. Detection limits are improved by the use of appropriate analog and digital filtering, ensemble averaging, and appropriate timing of repetitive cyclic voltammograms. The combined use of these techniques enables the in vivo detection of approximately 100 nM of dopamine with a signal-to-noise ratio of 25.
The arabidopsis cyclic nucleotide interactome
Donaldson, Lara
2016-05-11
Background Cyclic nucleotides have been shown to play important signaling roles in many physiological processes in plants including photosynthesis and defence. Despite this, little is known about cyclic nucleotide-dependent signaling mechanisms in plants since the downstream target proteins remain unknown. This is largely due to the fact that bioinformatics searches fail to identify plant homologs of protein kinases and phosphodiesterases that are the main targets of cyclic nucleotides in animals. Methods An affinity purification technique was used to identify cyclic nucleotide binding proteins in Arabidopsis thaliana. The identified proteins were subjected to a computational analysis that included a sequence, transcriptional co-expression and functional annotation analysis in order to assess their potential role in plant cyclic nucleotide signaling. Results A total of twelve cyclic nucleotide binding proteins were identified experimentally including key enzymes in the Calvin cycle and photorespiration pathway. Importantly, eight of the twelve proteins were shown to contain putative cyclic nucleotide binding domains. Moreover, the identified proteins are post-translationally modified by nitric oxide, transcriptionally co-expressed and annotated to function in hydrogen peroxide signaling and the defence response. The activity of one of these proteins, GLYGOLATE OXIDASE 1, a photorespiratory enzyme that produces hydrogen peroxide in response to Pseudomonas, was shown to be repressed by a combination of cGMP and nitric oxide treatment. Conclusions We propose that the identified proteins function together as points of cross-talk between cyclic nucleotide, nitric oxide and reactive oxygen species signaling during the defence response.
Cyclic cohomology of Hopf algebras
Crainic, M.
2001-01-01
We give a construction of ConnesMoscovicis cyclic cohomology for any Hopf algebra equipped with a character Furthermore we introduce a noncommutative Weil complex which connects the work of Gelfand and Smirnov with cyclic cohomology We show how the Weil complex arises naturally when looking at Hopf
Digital repetitive control under varying frequency conditions
Ramos Fuentes, Germán Andrés
2012-01-01
The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area and Repetitive Control has proven to be an efficient way to face this topic; however, in some applications the period of the signal to be tracked/rejected changes in time or is uncertain, which causes and important performance degradation in the standard repetitive controller. This thesis presents some contributions to the open topic of repetitive control workin...
[Repetition and fear of dying].
Lerner, B D
1995-03-01
In this paper a revision is made of the qualifications of Repetition (R) in Freuds work, i.e. its being at the service of the Pleasure Principle and, beyond it, the binding of free energy due to trauma. Freud intends to explain with this last concept the "fort-da" and the traumatic dreams (obsessively reiterated self-reproaches may be added to them). The main thesis of this work is that R. is not only a defense against the recollection of the ominous past (as in the metaphorical deaths of abandonment and desertion) but also a way of maintaining life and identify fighting against the inescapable omninous future (known but yet experienced), i.e. our own death. Some forms of R. like habits, identificatory behaviors and sometimes even magic, are geared to serve the life instinct. A literary illustration shows this desperate fight.
Pressure rig for repetitive casting
Vasquez, Peter (Inventor); Hutto, William R. (Inventor); Philips, Albert R. (Inventor)
1989-01-01
The invention is a pressure rig for repetitive casting of metal. The pressure rig performs like a piston for feeding molten metal into a mold. Pressure is applied to an expandable rubber diaphragm which expands like a balloon to force the metal into the mold. A ceramic cavity which holds molten metal is lined with blanket-type insulating material, necessitating only a relining for subsequent use and eliminating the lengthy cavity preparation inherent in previous rigs. In addition, the expandable rubber diaphragm is protected by the insulating material thereby decreasing its vulnerability to heat damage. As a result of the improved design the life expectancy of the pressure rig contemplated by the present invention is more than doubled. Moreover, the improved heat protection has allowed the casting of brass and other alloys with higher melting temperatures than possible in the conventional pressure rigs.
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.
Does a Randall-Sundrum scenario create the illusion of a torsion-free universe?
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.
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.
Autoparallel vs. Geodesic Trajectories in a Model of Torsion Gravity
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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.
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
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.
Torsional and Bending Vibration Measurement on Rotors Using Laser Technology
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.
Crack path in aeronautical titanium alloy under ultrasonic torsion loading
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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.
Torsion as a dark matter candidate from the Higgs portal
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.
Broughton, S Allen
2010-01-01
A cyclic $n$-gonal surface is a compact Riemann surface $X$ of genus $g\\geq 2$ admitting a cyclic group of conformal automorphisms $C$ of order $n$ such that the quotient space $X/C$ has genus 0. In this paper, we provide an overview of ongoing research into automorphism groups of cyclic $n$-gonal surfaces. Much of the paper is expository or will appear in forthcoming papers, so proofs are usually omitted. Numerous explicit examples are presented illustrating the computational methods currently being used to study these surfaces.
Comparing repetition-based melody segmentation models
Rodríguez López, M.E.; de Haas, Bas; Volk, Anja
2014-01-01
This paper reports on a comparative study of computational melody segmentation models based on repetition detection. For the comparison we implemented five repetition-based segmentation models, and subsequently evaluated their capacity to automatically find melodic phrase boundaries in a corpus of 2
Task Repetition and Second Language Speech Processing
Lambert, Craig; Kormos, Judit; Minn, Danny
2017-01-01
This study examines the relationship between the repetition of oral monologue tasks and immediate gains in L2 fluency. It considers the effect of aural-oral task repetition on speech rate, frequency of clause-final and midclause filled pauses, and overt self-repairs across different task types and proficiency levels and relates these findings to…
Repetitions: A Cross-Cultural Study.
Murata, Kumiko
1995-01-01
This study investigated how repetition is used in conversation among native speakers of British English, native speakers of Japanese, and Japanese speakers of English. Five interactional functions of repetition (interruption-orientated, solidarity, silence-avoidance, hesitation, and reformulation) were identified, as well as the cultural factors…
Digital repetitive control under varying frequency conditions
Ramos, Germán A; Olm, Josep M
2013-01-01
The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area. Repetitive Control has proven to be an efficient way to face this topic. However, in some applications the frequency of the reference/disturbance signal is time-varying or uncertain. This causes an important performance degradation in the standard Repetitive Control scheme. This book presents some solutions to apply Repetitive Control in varying frequency conditions without loosing steady-state performance. It also includes a complete theoretical development and experimental results in two representative systems. The presented solutions are organized in two complementary branches: varying sampling period Repetitive Control and High Order Repetitive Control. The first approach allows dealing with large range frequency variations while the second allows dealing with small range frequency variations. The book also presents applications of the described techniques to a Roto-magnet plant and...
Torsional wave propagation in multiwalled carbon nanotubes using nonlocal elasticity
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.
Early Universe Dynamos from Neutrino Oscillations Induced by Torsion
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_{\
A Case of Torsion of Gravid Uterus Caused by Leiomyoma
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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.
Equation of State of Gravitational Scalar-Torsion Mode
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.
Worldsheet Instantons and Torsion Curves, Part A: Direct Computation
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.
Spin-Rotation Coupling in Gravitation with Torsion
Institute of Scientific and Technical Information of China (English)
无
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.
Abnormalities of penile curvature: chordee and penile torsion.
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.
Standing torsional waves in a fully saturated, porous, circular cylinder
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.
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.
Abnormalities of Penile Curvature: Chordee and Penile Torsion
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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.
Torsion-balance experiments and ultra-low-mass fields
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.
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.
The geometro-hydrodynamical representation of the torsion field
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.
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.
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.
Deep learning methods for protein torsion angle prediction.
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.
Strategies for Using Repetition as a Powerful Teaching Tool
Saville, Kirt
2011-01-01
Brain research indicates that repetition is of vital importance in the learning process. Repetition is an especially useful tool in the area of music education. The success of repetition can be enhanced by accurate and timely feedback. From "simple repetition" to "repetition with the addition or subtraction of degrees of freedom," there are many…
Strategies for Using Repetition as a Powerful Teaching Tool
Saville, Kirt
2011-01-01
Brain research indicates that repetition is of vital importance in the learning process. Repetition is an especially useful tool in the area of music education. The success of repetition can be enhanced by accurate and timely feedback. From "simple repetition" to "repetition with the addition or subtraction of degrees of freedom," there are many…
Prognosis of Cyclic Vomiting Syndrome
Directory of Open Access Journals (Sweden)
J. Gordon Millichap
2016-03-01
Full Text Available Investigators from Teikyo University School of Medicine, Tokyo, Japan, evaluated the clinical features, prognosis, and prophylaxis of cyclic vomiting syndrome and the relationship between the syndrome and levels of adrenocorticotropic/antidiuretic hormones (ACTH/ADH.
National Research Council Canada - National Science Library
Piao, Yun-Song
2010-01-01
Recently, it has been noticed that the amplification of the amplitude of curvature perturbation cycle by cycle can lead to a cyclic multiverse scenario, in which the number of universes increases cycle by cycle...
Algebraic curves of maximal cyclicity
Caubergh, Magdalena; Dumortier, Freddy
2006-01-01
The paper deals with analytic families of planar vector fields, studying methods to detect the cyclicity of a non-isolated closed orbit, i.e. the maximum number of limit cycles that can locally bifurcate from it. It is known that this multi-parameter problem can be reduced to a single-parameter one, in the sense that there exist analytic curves in parameter space along which the maximal cyclicity can be attained. In that case one speaks about a maximal cyclicity curve (mcc) in case only the number is considered and of a maximal multiplicity curve (mmc) in case the multiplicity is also taken into account. In view of obtaining efficient algorithms for detecting the cyclicity, we investigate whether such mcc or mmc can be algebraic or even linear depending on certain general properties of the families or of their associated Bautin ideal. In any case by well chosen examples we show that prudence is appropriate.
Repetition priming from moving faces.
Lander, Karen; Bruce, Vicki
2004-06-01
Recent experiments have suggested that seeing a familiar face move provides additional dynamic information to the viewer, useful in the recognition of identity. In four experiments, repetition priming was used to investigate whether dynamic information is intrinsic to the underlying face representations. The results suggest that a moving image primes more effectively than a static image, even when the same static image is shown in the prime and the test phases (Experiment 1). Furthermore, when moving images are presented in the test phase (Experiment 2), there is an advantage for moving prime images. The most priming advantage is found with naturally moving faces, rather than with those shown in slow motion (Experiment 3). Finally, showing the same moving sequence at prime and test produced more priming than that found when different moving sequences were shown (Experiment 4). The results suggest that dynamic information is intrinsic to the face representations and that there is an advantage to viewing the same moving sequence at prime and test.
Torsional instability in suspension bridges: The Tacoma Narrows Bridge case
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.
A monolithically integrated torsional CMOS-MEMS relay
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.
Holography in 3D AdS gravity with torsion
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.
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.
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.
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.
Gravitational and torsion waves in linearised teleparallel gravity
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.
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.
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.
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.
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.
Singularities and n-dimensional black holes in torsion theories
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.
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....
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....
Cyclic Cushing's syndrome: an overview.
Albiger, Nora Maria Elvira; Scaroni, Carla M; Mantero, Franco
2007-11-01
Cyclic Cushing's syndrome (CS) is a disorder in which glucocorticoid levels are alternately normal and high, the latter occurring in episodes that can last from a few days to several months. It is more common in children than in adults. Cyclic CS may be either of the two different forms of CS (ACTH-dependent or -independent CS). Clinically, it may present with one or many symptoms, depending on the duration of disease activity and the timing of the fluctuations. A serotoninergic influence, cyclic changes in central dopaminergic tone, spontaneous episodic hemorrhage in the tumor, and the action of inflammatory cytokines with antitumor properties are some of the mechanisms suggested to explain the physiopathology of this phenomenon but the exact mechanism remains to be clarified. The cyclic pattern of hypercortisolism can delay the final diagnosis of CS and make it difficult to interpret the results of dynamic tests. Patients may have paradoxical responses to dexamethasone that can reflect increasing or decreasing levels of endogenous activity. Hormone assessments have to be repeated periodically when a diagnosis of CS is suspected. The cyclic pattern can also interfere with medical treatment because patients may show unexpected clinical and biochemical signs of hypocortisolism when cortisol secretion cyclically returns to normal, so an accurate follow-up is mandatory in these patients.
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.
Precision markedly attenuates repetitive lift capacity.
Collier, Brooke R; Holland, Laura; McGhee, Deirdre; Sampson, John A; Bell, Alison; Stapley, Paul J; Groeller, Herbert
2014-01-01
This study investigated the effect of precision on time to task failure in a repetitive whole-body manual handling task. Twelve participants were required to repetitively lift a box weighing 65% of their single repetition maximum to shoulder height using either precise or unconstrained box placement. Muscle activity, forces exerted at the ground, 2D body kinematics, box acceleration and psychophysical measures of performance were recorded until task failure was reached. With precision, time to task failure for repetitive lifting was reduced by 72%, whereas the duration taken to complete a single lift and anterior deltoid muscle activation increased by 39% and 25%, respectively. Yet, no significant difference was observed in ratings of perceived exertion or heart rate at task failure. In conclusion, our results suggest that when accuracy is a characteristic of a repetitive manual handling task, physical work capacity will decline markedly. The capacity to lift repetitively to shoulder height was reduced by 72% when increased accuracy was required to place a box upon a shelf. Lifting strategy and muscle activity were also modified, confirming practitioners should take into consideration movement precision when evaluating the demands of repetitive manual handling tasks.
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.
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.
Left common basal pyramid torsion following left upper lobectomy/segmentectomy.
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.
A 55-Year-Old Man with Right Testicular Pain: Too Old for Torsion?
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.
Successive Torsion of the Right Middle and Left Cranial Lung Lobes in a Dog
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).
Jones, David J.; Kurath, Peter
1988-01-01
Fully reversed uniaxial strain controlled fatigue tests were performed on smooth cylindrical specimens made of 304 stainless steel. Fatigue life data and cracking observations for uniaxial tests were compared with life data and cracking behavior observed in fully reversed torsional tests. It was determined that the product of maximum principle strain amplitude and maximum principle stress provided the best correlation of fatigue lives for these two loading conditions. Implementation of this parameter is in agreement with observed physical damage and it accounts for the variation of stress-strain response, which is unique to specific loading conditions. Biaxial fatigue tests were conducted on tubular specimens employing both in-phase and out-of-phase tension torsion cyclic strain paths. Cracking observations indicated that the physical damage which occurred in the biaxial tests was similar to the damage observed in uniaxial and torsional tests. The Smith, Watson, and Topper parameter was then extended to predict the fatigue lives resulting from the more complex loading conditions.
Transitive oriented 3-Hypergraphs of cyclic orders
2012-01-01
In this paper we introduce the definition of transitivity for oriented 3-hypergraphs in order to study partial and complete cyclic orders. This definition allow us to give sufficient conditions on a partial cyclic order to be totally extendable. Furthermore, we introduce the 3-hypergraph associated to a cyclic permutation and characterize it in terms of cyclic comparability 3-hypergraphs.
Dirac theory in space-time without torsion
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.
Ocular torsion before and after 1 hour centrifugation
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
Numerical Simulation of Gleeble Torsion Testing of HSLA-65 Steel
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
Torsion stiffness of a protein pair determined by magnetic particles
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
Ectopic ovary with torsion: uncommon diagnosis made by ultrasound
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
Torsion and CO-stretching vibration interactions in methanol
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.
The human ocular torsion position response during yaw angular acceleration.
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.
Torsional Newton-Cartan geometry and the Schrodinger algebra
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
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
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...
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.
Determination of ocular torsion by means of automatic pattern recognition
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
Direct excitation of resonant torsional Alfven waves by footpoint motions
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
Contravariantly finite subcategories in a tilting torsion class
Institute of Scientific and Technical Information of China (English)
无
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.
Anomalous Majorana Neutrino Masses from Torsionful Quantum Gravity
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...
Ponzano-Regge Model on Manifold with Torsion
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...
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.
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.
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...
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...
Repetitive Bibliographical Information in Relational Databases.
Brooks, Terrence A.
1988-01-01
Proposes a solution to the problem of loading repetitive bibliographic information in a microcomputer-based relational database management system. The alternative design described is based on a representational redundancy design and normalization theory. (12 references) (Author/CLB)
Computer-Related Repetitive Stress Injuries
... on the shoulder Epicondylitis: elbow soreness often called "tennis elbow" Ganglion cyst: swelling or lump in the wrist ... Bones, Muscles, and Joints Carpal Tunnel Syndrome Medial Epicondylitis Repetitive Stress Injuries Contact Us Print Resources Send ...
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.
Development of a Meso-Scale SMA-Based Torsion Actuator for Image-Guided Procedures.
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.
Digital repetitive control under varying frequency conditions
Ramos Fuentes, Germán Andrés
2012-01-01
Premi extraordinari doctorat curs 2011-2012, àmbit d’Enginyeria Industrial The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area and Repetitive Control has proven to be an efficient way to face this topic; however, in some applications the period of the signal to be tracked/rejected changes in time or is uncertain, which causes and important performance degradation in the standard repetitive controller. This the...
Torsional vibration measurements on rotating shaft system using laser doppler vibrometer
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.
Manual for Cyclic Triaxial Test
DEFF Research Database (Denmark)
Shajarati, Amir; Sørensen, Kris Wessel; Nielsen, Søren Kjær
/dynamic triaxial cell is overall constructed in the same way as the static triaxial cell at Aalborg University, but with the ability to apply any kind of load sequence to the test sample. When conducting cyclic triaxial tests, it is recommended that the manual is followed very tediously since there are many steps...... and if they are done improperly or in the wrong order there is a risk of destroying the test sample or obtaining invalid results.......This manual describes the different steps that is included in the procedure for conducting a cyclic triaxial test at the geotechnical Laboratory at Aalborg University. Furthermore it contains a chapter concerning some of the background theory for the static triaxial tests. The cyclic...
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.
Olson, Michael W; Li, Li; Solomonow, Moshe
2009-02-01
Human and animal models using electromyography (EMG) based methods have hypothesized that viscoelastic tissue properties becomes compromised by prolonged repetitive cyclic trunk flexion-extension which in turn influences muscular activation including the flexion-relaxation phenomenon. Empirical evidence to support this hypothesis, especially the development of viscoelastic tension-relaxation and its associated muscular response in passive cyclic activity in humans, is incomplete. The objective of this study was to examine the response of lumbar muscles to tension-relaxation development of the viscoelastic tissue during prolonged passive cyclic trunk flexion-extension. Activity of the lumbar muscles remained low and steady during the passive exercise session. Tension supplied by the posterior viscoelastic tissues decreased over time without corresponding changes in muscular activity. Active flexion, following the passive flexion session, elicited significant increase in paraspinal muscles EMG together with increase in the median frequency. It was concluded that reduction of tension in the lumbar viscoelastic tissues of humans occurs during cyclic flexion-extension and is compensated by increased activity of the musculature in order to maintain stability. It was also concluded that the ligamento-muscular reflex is inhibited during passive activities but becomes hyperactive following active cyclic flexion, indicating that moment requirements are the controlling variable. It is conceived that prolonged routine exposure to cyclic flexion minimizes the function of the viscoelastic tissues and places increasing demands on the neuromuscular system which over time may lead to a disorder and possible exposure to injury.
Ramesh, Nivarthi; Sarangi, Nirod Kumar; Patnaik, Archita
2013-05-01
Soft molecular ellipsoids conceived from 3,4-di(dodecyloxy)benzoic acid (DDBA) amphiphile draw attention to monomer structure design, intramolecular -COOH headgroup twist (ϕ°) and cyclic-acyclic dimer switching through facial H-bond torsion (ψ°). Generically, precipitation in hydrogen bonded systems has been the prime phenomenon once the critical aggregation concentrations were reached in the bulk solution. DDBA was no exception to this generalization. It formed precipitates in chloroform and methanol with no specific geometry but with cyclic dimer motifs in them. On the contrary, surface pressure modulated interfacial aggregation with ellipsoidal geometry followed acyclic dimerization (catemer motif) with various levels of headgroup torsion, established through real-time polarization modulated infrared reflection-absorption spectroscopy (IRRAS) and density functional theory (DFT) calculations, that estimated the energy costs for these unexplored pathways. The reaction coordinates ϕ° and ψ° in consonance with 2D surface pressure modulation thus directed the shape anisotropy during the dynamic self-assembly of DDBA. Changes in subphase pH and metal ionic environment had a derogatory effect on the ellipsoid formation, the structural requirement for which strictly followed a stringent need for twin alkyl chains in an asymmetric unit cell, as 4-dodecyloxybenzoic acid (MABA) with a single alkyl chain formed exclusively spherical assemblies with no dimer modulation. The investigation thus reports unexplored energy pathways toward ellipsoidal geometry of the amphiphile in the course of its interfacial aggregation.
Hopf cyclic cohomology and transverse characteristic classes
Moscovici, Henri
2010-01-01
By refining the cyclic cohomological apparatus for computing the Hopf cyclic cohomology of the Hopf algebras associated to infinite primitive Cartan-Lie pseudogroup, we explicitly identify, as a Hopf cyclic complex, the image of the canonical homomorphism from the Gelfand-Fuks complex to the Bott complex for equivariant cohomology. Distinct from the original realization due to A. Connes and the first named author of the cyclic cohomology of such Hopf algebras as differentiable cyclic cohomology, this construction provides a convenient front-end model for their Hopf cyclic cohomology. Relying on it, we produce characteristic homomorphisms from newly developed models for Hopf cyclic characteristic classes to the cyclic cohomology of the convolution algebras of \\'etale holonomy groupoids, which in particular work in the relative case with no compactness restriction. As an illustration, we apply the latter feature to transfer the universal Hopf cyclic Chern classes found by us in a previous paper, and produce in ...
Energy Technology Data Exchange (ETDEWEB)
Piao Yunsong, E-mail: yspiao@gucas.ac.c [College of Physical Sciences, Graduate School of Chinese Academy of Sciences, Beijing 100049 (China)
2010-08-09
Recently, it has been noticed that the amplification of the amplitude of curvature perturbation cycle by cycle can lead to a cyclic multiverse scenario, in which the number of universes increases cycle by cycle. However, this amplification will also inevitably induce either the ultimate end of corresponding cycle, or the resulting spectrum of perturbations inside corresponding universe is not scale invariant, which baffles the existence of observable universes. In this Letter, we propose a design of a cyclic multiverse, in which the observable universe can emerges naturally. The significance of a long period of dark energy before the turnaround of each cycle for this implementing is shown.
Recursive processing of cyclic graphs.
Bianchini, Monica; Gori, Marco; Sarti, Lorenzo; Scarselli, Franco
2006-01-01
Recursive neural networks are a powerful tool for processing structured data. According to the recursive learning paradigm, the input information consists of directed positional acyclic graphs (DPAGs). In fact, recursive networks are fed following the partial order defined by the links of the graph. Unfortunately, the hypothesis of processing DPAGs is sometimes too restrictive, being the nature of some real-world problems intrinsically cyclic. In this paper, a methodology is proposed, which allows us to process any cyclic directed graph. Therefore, the computational power of recursive networks is definitely established, also clarifying the underlying limitations of the model.
The Prevalence and Phenomenology of Repetitive Behavior in Genetic Syndromes
Moss, Joanna; Oliver, Chris; Arron, Kate; Burbidge, Cheryl; Berg, Katy
2009-01-01
We investigated the prevalence and phenomenology of repetitive behavior in genetic syndromes to detail profiles of behavior. The Repetitive Behaviour Questionnaire (RBQ) provides fine-grained identification of repetitive behaviors. The RBQ was employed to examine repetitive behavior in Angelman (N = 104), Cornelia de Lange (N = 101), Cri-du-Chat…
Color visualization of cyclic magnitudes
Restrepo, Alfredo; Estupiñán, Viviana
2014-02-01
We exploit the perceptual, circular ordering of the hues in a technique for the visualization of cyclic variables. The hue is thus meaningfully used for the indication of variables such as the azimuth and the units of the measurement of time. The cyclic (or circular) variables may be both of the continuous type or the discrete type; among the first there is azimuth and among the last you find the musical notes and the days of the week. A correspondence between the values of a cyclic variable and the chromatic hues, where the natural circular ordering of the variable is respected, is called a color code for the variable. We base such a choice of hues on an assignment of of the unique hues red, yellow, green and blue, or one of the 8 even permutations of this ordered list, to 4 cardinal values of the cyclic variable, suitably ordered; color codes based on only 3 cardinal points are also possible. Color codes, being intuitive, are easy to remember. A possible low accuracy when reading instruments that use this technique is compensated by fast, ludic and intuitive readings; also, the use of a referential frame makes readings precise. An achromatic version of the technique, that can be used by dichromatic people, is proposed.
Indian Academy of Sciences (India)
Manju Pruthi
2001-11-01
In this paper explicit expressions of + 1 idempotents in the ring $R = F_q[X]/\\langle X^{2^m}-1\\rangle$ are given. Cyclic codes of length 2 over the finite field , of odd characteristic, are defined in terms of their generator polynomials. The exact minimum distance and the dimension of the codes are obtained.
Likelihood methods and classical burster repetition
Graziani, C; Graziani, Carlo; Lamb, Donald Q
1995-01-01
We develop a likelihood methodology which can be used to search for evidence of burst repetition in the BATSE catalog, and to study the properties of the repetition signal. We use a simplified model of burst repetition in which a number N_{\\rm r} of sources which repeat a fixed number of times N_{\\rm rep} are superposed upon a number N_{\\rm nr} of non-repeating sources. The instrument exposure is explicitly taken into account. By computing the likelihood for the data, we construct a probability distribution in parameter space that may be used to infer the probability that a repetition signal is present, and to estimate the values of the repetition parameters. The likelihood function contains contributions from all the bursts, irrespective of the size of their positional errors --- the more uncertain a burst's position is, the less constraining is its contribution. Thus this approach makes maximal use of the data, and avoids the ambiguities of sample selection associated with data cuts on error circle size. We...
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.)
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.
Torsional Newton-Cartan Geometry from the Noether Procedure
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.
Torsional Newton-Cartan geometry from the Noether procedure
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.
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.
Drinfeld modules with maximal Galois action on their torsion points
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.
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.
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.
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.
[Uterine torsion in cattle - frequency, clinical symptoms and theories about the pathogenesis].
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.
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.
Electron as the eigenstate of curvilinear space with torsion
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.
A supersymmetric R2-action in six dimensions and torsion
Bergshoeff, E.; Salam, Abdus; Sezgin, E.
1986-01-01
The superconformal extension of (RÂµÎ½ab)2 is given in six dimensions. It is shown that in a superconformal gauge the three-form field HÂµÎ½Ï� has a natural torsion interpretation. Also partial results are given on the superconformal extension of the Gauss-Bonnet combination R2ÂµÎ½ab - 4R2Âµa + R2.
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.
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.
Search for Possible Connections of Sunspot Features and Torsional Waves
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.
Spectroscopy in the Presence of Geometrical Constraints: A Torsional Pendulum
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.
On Polya's inequality for torsional rigidity and first Dirichlet eigenvalue
Berg, M. van den; Ferone, V.; Nitsch, C.; Trombetti, C.
2016-01-01
Let $\\Omega$ be an open set in Euclidean space with finite Lebesgue measure $|\\Omega|$. We obtain some properties of the set function $F:\\Omega\\mapsto \\R^+$ defined by $$ F(\\Omega)=\\frac{T(\\Omega)\\lambda_1(\\Omega)}{|\\Omega|} ,$$ where $T(\\Omega)$ and $\\lambda_1(\\Omega)$ are the torsional rigidity and the first eigenvalue of the Dirichlet Laplacian respectively. We improve the classical P\\'olya bound $F(\\Omega)\\le 1,$ and show that $$F(\\Omega)\\le 1- \
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.
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.
Torsion of the greater omentum: treatment by laparoscopy.
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.
VERIFICATION OF TORSIONAL OSCILLATING MECHANICAL SYSTEM DYNAMIC CALCULATION RESULTS
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...
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...
Preliminary Results from the Large Volume Torsion (LVT) Deformation Apparatus
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.
A gluing formula for the analytic torsion on singular spaces
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 ...
Solar neutrinos, helicity effects and new affine gravity with torsion
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.
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.
Measurement of ocular torsion variation following superior oblique tenectomy
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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.
Shape sensing for torsionally compliant concentric-tube robots
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.
Diesel engine torsional vibration control coupling with speed control system
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.
Scalar torsion and a new symmetry of general relativity
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...
On the torsional loading of elastoplastic spheres in contact
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.
Torsional stiffness degradation and aerostatic divergence of suspension bridge decks
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.
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.
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.
Powers of Convex-Cyclic Operators
Directory of Open Access Journals (Sweden)
Fernando León-Saavedra
2014-01-01
Full Text Available A bounded operator T on a Banach space X is convex cyclic if there exists a vector x such that the convex hull generated by the orbit Tnxn≥0 is dense in X. In this note we study some questions concerned with convex-cyclic operators. We provide an example of a convex-cyclic operator T such that the power Tn fails to be convex cyclic. Using this result we solve three questions posed by Rezaei (2013.
CYCLIC CODES OVER FORMAL POWER SERIES RINGS
Institute of Scientific and Technical Information of China (English)
Dougherty Steven T.; Liu Hongwei
2011-01-01
In this article, cyclic codes and negacyclic codes over formal power series rings are studied. The structure of cyclic codes over this class of rings is given, and the relationship between these codes and cyclic codes over finite chain rings is obtained. Using an isomorphism between cyclic and negacyclic codes over formal power series rings, the structure of negacyclic codes over the formal power series rings is obtained.
40 CFR 721.2120 - Cyclic amide.
2010-07-01
... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Cyclic amide. 721.2120 Section 721... Cyclic amide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a cyclic amide (PMN P-92-131) is subject to reporting under this section for...
The cyclic theory of Hopf algebroids
Kowalzig, N.; Posthuma, H.
2011-01-01
We give a systematic description of the cyclic cohomology theory of Hopf alge\\-broids in terms of its associated category of modules. Then we introduce a dual cyclic homology theory by applying cyclic duality to the underlying cocyclic object. We derive general structure theorems for these theories
The Cyclic Graph of a Finite Group
Directory of Open Access Journals (Sweden)
Xuan Long Ma
2013-01-01
and characterize certain finite groups whose cyclic graphs have some properties. Then, we present some properties of the cyclic graphs of the dihedral groups D2n and the generalized quaternion groups Q4n for some n. Finally, we present some parameters about the cyclic graphs of finite noncyclic groups of order up to 14.
Energy Technology Data Exchange (ETDEWEB)
Fesich, Thomas M.; Herter, Karl-Heinz; Schuler, Xaver
2012-12-15
Objective of the project was the experimental assurance of investigations on the theoretical basis of multiaxial fatigue loading. The review of the applicability of existing hypotheses, as well as the extension of the corresponding data base was carried out by experimental studies in fatigue tests under complex multiaxial loading for a ferritic and austenitic material. To investigate the influence of complex multiaxial stress conditions on the fatigue behavior, in this project notched cylindrical specimens were examined under alternating tensile/pressure loading and alternating torsional loading. Through the notch in the notched section inhomogeneous, multiaxial stress states are generated. By uniaxial alternating tests on unnotched specimens and a further series of tests on unnotched specimens under alternating torsional loading an evaluation of the impact and influence of the notch of stress on fatigue behavior was possible. A series of experiments with superimposition of alternating torsional and alternating tensile/pressure loading permits verification of the effect of phase-shifted stress and rotating principal coordinate system. All experiments were performed at room temperature. As part of the research project, the experimental results with the ferritic and austenitic materials were evaluated in terms of material behavior (hardening or softening) under cyclic loading. These were to uniaxial alternating tensile/pressure tests, alternating torsional tests (unnotched cylindrical specimens), alternating tensile/pressure tests on notched cylindrical specimens, alternating torsional tests on notched cylindrical specimens, alternating tensiontorsion tests with complex proportional stresses on unnotched cylindrical specimens (superimposition of normal and shear stress components), as well as alternating tension-torsion tests with complex non-proportional strain on unnotched cylindrical specimens (superimposition of normal and shear stress components with 90 phase
Bocher, L.; Delobelle, P.
1997-09-01
This paper is concerned with the experimental determination of the behaviour of a 316 L austenitic stainless steel at room temperature and under non proportional cyclic strainings in tension-torsion- internal and external pressures. The two or three sinusoïdal strains were applied both in and out-of-phase and the main investigations deal with the additional hardening due to multiaxiality of the loadings. Typical stabilized hysteresis loops are presented. With respect to the maximum additional hardening the different tests can be classified as follows : in phase tests, out-of-phase internal-external pressures tests, out-of-phase tension-torsion tests and finally tension-torsion-pressure with significant phase angles A device is presented which allows cyclic tests to be performed on tubes for loadings in tension-torsion-internal and external pressures. It is composed of a medium pressure chamber enclosing the gage length of the test specimen, directly fixed on the specimen and connected to two pressure regulators. The specimen is also fastened to the jaws of a hydraulic tensile-torsion machine through two extension rods. The entire device is controlled with the help of strain gauges set directly on the gage zone of the test specimen. Different tests have been performed at ambient temperature on an austenitic stainless steel which has the particularity of presenting a strong supplementary hardening connected to the non-radiality of the loadings. The influence of the phase shift parameters, namely the angles δ and \\varphi (δ: tension-torsion, \\varphi: tension-pressures) for two or three cyclic sinusoïdal components and for a total equivalent strain amplitude level imposed at 0.4% was studied. The ratios of the maximum strain amplitudes were respectively fixed at r_2 = 1 and r_1 = ± 1 (r_2: tension-torsion and r_1: tension-pressures). These tests allowed both the hypotheses made in stress calculations and the whole of the experimental set up to be validated. They
Le Guen, Morgan; Naline, Emmanuel; Grassin-Delyle, Stanislas; Devillier, Philippe; Faisy, Christophe
2015-01-01
Background Mechanical ventilation may induce harmful effects in the airways of critically ill patients. Nevertheless, the effects of cyclic stretching caused by repetitive inflation-deflation of the bronchial compartment have not been well characterized in humans. The objective of the present study was to assess the effectiveness of a load-imposing device for the cyclic stretching of human bronchi. Methods Intact bronchial segments were removed from 128 thoracic surgery patients. After preparation and equilibration in an organ bath, bronchi were stretched repetitively and cyclically with a motorized transducer. The peak force imposed on the bronchi was set to 80% of each individual maximum contraction in response to acetylcholine and the minimal force corresponded to the initial basal tone before stretching. A 1-min cycle (stretching for 15 sec, relaxing for 15 sec and resting for 30 sec) was applied over a time period ranging from 5 to 60 min. The device's performance level was assessed and the properties of the stretched bronchi were compared with those of paired, non-stretched bronchi. Results Despite the intrinsic capacities of the device, the targets of the tension adjustments remained variable for minimal tension (156–178%) while the peak force set point was unchanged (87–115%). In the stretched bronchi, a time-dependent rise in basal tone (P stretched) was apparent after as little as 5 min of cyclic stretching. The stretch-induced rise in basal tone continued to increase (P stretching had ended. Only 60 min of cyclic stretching was associated with a significant (P stretched bronchi. Conclusions Low-frequency, low-force, cyclic loading of human bronchi is associated with elevated basal tone and acetylcholine responsiveness. The present experimental model is likely to be a useful tool for future investigations of the bronchial response to repetitive stress during mechanical ventilation. PMID:26011598
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.
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
Primordial magnetic fields of non-minimal photon-torsion axial coupling origin
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 ...
Cyclical Fluctuations in Workplace Accidents
Boone, J.; J. C. VAN OURS
2002-01-01
This Paper presents a theory and an empirical investigation on cyclical fluctuations in workplace accidents. The theory is based on the idea that reporting an accident dents the reputation of a worker and raises the probability that he is fired. Therefore a country with a high or an increasing unemployment rate has a low (reported) workplace accident rate. The empirical investigation concerns workplace accidents in OECD countries. The analysis confirms that workplace accident rates are invers...
Effective coarse-grained simulations of super-thick multi-walled carbon nanotubes under torsion
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...
Acute torsion of a retroperitoneal renal transplant mimicking renal vein thrombosis.
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.
Mechanically-Assisted Current-Induced Switching of the Magnetic Moment in a Torsional Oscillator
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...
Supramolecular nesting of cyclic polymers.
Kondratuk, Dmitry V; Perdigão, Luís M A; Esmail, Ayad M S; O'Shea, James N; Beton, Peter H; Anderson, Harry L
2015-04-01
Advances in template-directed synthesis make it possible to create artificial molecules with protein-like dimensions, directly from simple components. These synthetic macromolecules have a proclivity for self-organization that is reminiscent of biopolymers. Here, we report the synthesis of monodisperse cyclic porphyrin polymers, with diameters of up to 21 nm (750 C–C bonds). The ratio of the intrinsic viscosities for cyclic and linear topologies is 0.72, indicating that these polymers behave as almost ideal flexible chains in solution. When deposited on gold surfaces, the cyclic polymers display a new mode of two-dimensional supramolecular organization, combining encapsulation and nesting; one nanoring adopts a near-circular conformation, thus allowing a second nanoring to be captured within its perimeter, in a tightly folded conformation. Scanning tunnelling microscopy reveals that nesting occurs in combination with stacking when nanorings are deposited under vacuum, whereas when they are deposited directly from solution under ambient conditions there is stacking or nesting, but not a combination of both.
The neurobiology of repetitive behavior : of mice…
Langen, Marieke; Kas, Martien J H; Staal, Wouter G; van Engeland, Herman; Durston, Sarah
2011-01-01
Repetitive and stereotyped behavior is a prominent element of both animal and human behavior. Similar behavior is seen across species, in diverse neuropsychiatric disorders and in key phases of typical development. This raises the question whether these similar classes of behavior are caused by simi
Large-scale detection of repetitions.
Smyth, W F
2014-05-28
Combinatorics on words began more than a century ago with a demonstration that an infinitely long string with no repetitions could be constructed on an alphabet of only three letters. Computing all the repetitions (such as ∙∙∙TTT ∙∙∙ or ∙∙∙ CGACGA ∙∙∙ ) in a given string x of length n is one of the oldest and most important problems of computational stringology, requiring time in the worst case. About a dozen years ago, it was discovered that repetitions can be computed as a by-product of the Θ(n)-time computation of all the maximal periodicities or runs in x. However, even though the computation is linear, it is also brute force: global data structures, such as the suffix array, the longest common prefix array and the Lempel-Ziv factorization, need to be computed in a preprocessing phase. Furthermore, all of this effort is required despite the fact that the expected number of runs in a string is generally a small fraction of the string length. In this paper, I explore the possibility that repetitions (perhaps also other regularities in strings) can be computed in a manner commensurate with the size of the output.
Verbal Repetitions and Echolalia in Alzheimer's Discourse
Da Cruz, Fernanda Miranda
2010-01-01
This article reports on an investigation of echolalic repetition in Alzheimer's disease (AD). A qualitative analysis of data from spontaneous conversations with MHI, a woman with AD, is presented. The data come from the DALI Corpus, a corpus of spontaneous conversations involving subjects with AD. This study argues that echolalic effects can be…
Neurobehavioural Correlates of Abnormal Repetitive Behaviour
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R. A. Ford
1991-01-01
Full Text Available Conditions in which echolalia and echopraxia occur are reviewed, followed by an attempt to elicit possible mechanisms of these phenomena. A brief description of stereotypical and perseverative behaviour and obsessional phenomena is given. It is suggested that abnormal repetitive behaviour may occur partly as a result of central dopaminergic dysfunction.
Reducing Repetitive Speech: Effects of Strategy Instruction.
Dipipi, Caroline M.; Jitendra, Asha K.; Miller, Judith A.
2001-01-01
This article describes an intervention with an 18-year-old young woman with mild mental retardation and a seizure disorder, which focused on her repetitive echolalic verbalizations. The intervention included time delay, differential reinforcement of other behaviors, and self-monitoring. Overall, the intervention was successful in facilitating…
Verbal Repetitions and Echolalia in Alzheimer's Discourse
Da Cruz, Fernanda Miranda
2010-01-01
This article reports on an investigation of echolalic repetition in Alzheimer's disease (AD). A qualitative analysis of data from spontaneous conversations with MHI, a woman with AD, is presented. The data come from the DALI Corpus, a corpus of spontaneous conversations involving subjects with AD. This study argues that echolalic effects can be…
Unusual cause of acute abdominal pain in a postmenopausal woman: adnexal torsion
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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
Gravitational waves and magnetic monopoles during inflation with Weitzenb\\"ock torsion
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.
Tibial torsion in non-arthritic Indian adults: A computer tomography study of 100 limbs
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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.
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.
Running coupling in electroweak interactions of leptons from f(R)-gravity with torsion
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.
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.)
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)
Gravitational waves and magnetic monopoles during inflation with Weitzenböck torsion
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.
An investigation on the behaviour and stiffness of reinforced concrete slabs subjected to torsion
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.
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.
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.
Woods, R Jeremy; Brower, Justin O; Castellanos, Elena; Hashemzadeh, Mehrnoosh; Khakshoor, Omid; Russu, Wade A; Nowick, James S
2007-03-07
The development of peptide beta-hairpins is problematic, because folding depends on the amino acid sequence and changes to the sequence can significantly decrease folding. Robust beta-hairpins that can tolerate such changes are attractive tools for studying interactions involving protein beta-sheets and developing inhibitors of these interactions. This paper introduces a new class of peptide models of protein beta-sheets that addresses the problem of separating folding from the sequence. These model beta-sheets are macrocyclic peptides that fold in water to present a pentapeptide beta-strand along one edge; the other edge contains the tripeptide beta-strand mimic Hao [JACS 2000, 122, 7654] and two additional amino acids. The pentapeptide and Hao-containing peptide strands are connected by two delta-linked ornithine (deltaOrn) turns [JACS 2003, 125, 876]. Each deltaOrn turn contains a free alpha-amino group that permits the linking of individual modules to form divalent beta-sheets. These "cyclic modular beta-sheets" are synthesized by standard solid-phase peptide synthesis of a linear precursor followed by solution-phase cyclization. Eight cyclic modular beta-sheets 1a-1h containing sequences based on beta-amyloid and macrophage inflammatory protein 2 were synthesized and characterized by 1H NMR. Linked cyclic modular beta-sheet 2, which contains two modules of 1b, was also synthesized and characterized. 1H NMR studies show downfield alpha-proton chemical shifts, deltaOrn delta-proton magnetic anisotropy, and NOE cross-peaks that establish all compounds but 1c and 1g to be moderately or well folded into a conformation that resembles a beta-sheet. Pulsed-field gradient NMR diffusion experiments show little or no self-association at low (
Sectoral Shifts and Cyclical Fluctuations Sectoral Shifts and Cyclical Fluctuations
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Richard Rogerson
1991-03-01
Full Text Available Sectoral Shifts and Cyclical Fluctuations This paper studies a two sector real business cycle model in which the sectors experience different trend rates of growth and labor mobility is costly. Predictions are derived concerning the correlation between sectoral reallocation of workers and the cycle. This correlation may be positive or negative depending upon whether the growing sector displays larger or smaller fluctuations than the shrinking sector. The post- World War II period has witnessed two major patterns of sectoral change in industrialized countries: movement out of agriculture and movement out of the industrial sector. The model's basic prediction is shown to be consistent with the observed pattern of reallocation.
Focal point analysis of torsional isomers of acrylic acid
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.
[The functional sport shoe parameter "torsion" within running shoe research--a literature review].
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.
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.
Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex
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
Torsional dynamics and orientation of DNA-DAPI complexes
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...
Torsional Detwinning Domino in Nanotwinned One-Dimensional Nanostructures.
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.
A Torsion-Balance Search for Axion-Like Particles
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.
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.
Photoelectronic vibrometer with polarized light. [for torsional vibration measurements
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.
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.
Isotropic Stars in Higher-Order Torsion Scalar Theories
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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.
Isotropic stars in higher-order torsion scalar theories
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.
Slip measurement in a frictional connection by torsional LDV
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
Torsion-free generalized connections and Heterotic Supergravity
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.
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.
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.
On the addition of torsion to chiral gravity
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.
The cyclical component factor model
DEFF Research Database (Denmark)
Dahl, Christian Møller; Hansen, Henrik; Smidt, John
Forecasting using factor models based on large data sets have received ample attention due to the models' ability to increase forecast accuracy with respect to a range of key macroeconomic variables in the US and the UK. However, forecasts based on such factor models do not uniformly outperform...... the simple autoregressive model when using data from other countries. In this paper we propose to estimate the factors based on the pure cyclical components of the series entering the large data set. Monte Carlo evidence and an empirical illustration using Danish data shows that this procedure can indeed...
Cyclic voltammetry of supported BLMs
Murgasova, Renata; Sabo, Jan; Ottova, Angelica L.; Tien, H. T.
1996-06-01
The transfer of an electron across a bilayer lipid membrane (BLM) is one of the BLMs most exciting processes. A number of well known electron mediators have been investigated using the method of cyclic voltammetry on a Teflon coated platinum wire, the tip of which has been modified by a self-assembled bilayer lipid membrane (s-BLM). The electrical capacitance of the s-BLM system was measured as a function of frequency. The results are discussed in terms of electron transfer and redox reactions.
Robust Repetitive Controller for Fast AFM Imaging
Necipoglu, Serkan; Has, Yunus; Guvenc, Levent; Basdogan, Cagatay
2012-01-01
Currently, Atomic Force Microscopy (AFM) is the most preferred Scanning Probe Microscopy (SPM) method due to its numerous advantages. However, increasing the scanning speed and reducing the interaction forces between the probe's tip and the sample surface are still the two main challenges in AFM. To meet these challenges, we take advantage of the fact that the lateral movements performed during an AFM scan is a repetitive motion and propose a Repetitive Controller (RC) for the z-axis movements of the piezo-scanner. The RC utilizes the profile of the previous scan line while scanning the current line to achieve a better scan performance. The results of the scanning experiments performed with our AFM set-up show that the proposed RC significantly outperforms a conventional PI controller that is typically used for the same task. The scan error and the average tapping forces are reduced by 66% and 58%, respectively when the scan speed is increased by 7-fold.
A repetitive elements perspective in Polycomb epigenetics.
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Valentina eCasa
2012-10-01
Full Text Available Repetitive elements comprise over two-thirds of the human genome. For a long time, these elements have received little attention since they were considered non functional. On the contrary, recent evidence indicates that they play central roles in genome integrity, gene expression and disease. Indeed, repeats display meiotic instability associated with disease and are located within common fragile sites, which are hotspots of chromosome rearrangements in tumors. Moreover, a variety of diseases have been associated with aberrant transcription of repetitive elements. Overall this indicates that appropriate regulation of repetitive elements’ activity is fundamental.Polycomb group (PcG proteins are epigenetic regulators that are essential for the normal development of multicellular organisms. Mammalian PcG proteins are involved in fundamental processes, such as cellular memory, cell proliferation, genomic imprinting, X-inactivation, and cancer development. PcG proteins can convey their activity through long-distance interactions also on different chromosomes. This indicates that the 3D organization of PcG proteins contributes significantly to their function. However, it is still unclear how these complex mechanisms are orchestrated and which role PcG proteins play in the multi-level organization of gene regulation. Intriguingly, the greatest proportion of Polycomb-mediated chromatin modifications is located in genomic repeats and it has been suggested that they could provide a binding platform for Polycomb proteins.Here, these lines of evidence are woven together to discuss how repetitive elements could contribute to chromatin organization in the 3D nuclear space.
Emotional arousal enhances word repetition priming
Thomas, Laura A.; LaBar, Kevin S.
2005-01-01
Three experiments were conducted to determine if emotional content increases repetition priming magnitude. In the study phase of Experiment 1, participants rated high-arousing negative (taboo) words and neutral words for concreteness. In the test phase, they made lexical decision judgements for the studied words intermixed with novel words (half taboo, half neutral) and pseudowords. In Experiment 2, low-arousing negative (LAN) words were substituted for the taboo words, and in Experiment 3 al...
The Rhythms of Echo. Variations on Repetition
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Rosa María Aradra Sánchez
2015-04-01
Full Text Available This paper presents a study on the echo as metric and rhetorical procedure. It makes a brief tour through some of the poetic manifestations of echo in the Spanish literary tradition, and a brief tour through the attention that metric theory has paid to this phenomenon. Then it stops at the possibilities that rhetoric offers for its analysis from the generic approach of the discursive repetition phenomena.
Repetitive behaviour in autism: Imaging pathways and trajectories
Langen, M.J.G.
2009-01-01
Repetitive behaviour in autism: Imaging pathways and trajectories Repetitive and rigid behaviour is one of the core symptoms of autism, a severe and lifelong child psychiatric disorder. Although repetitive behaviour symptoms often form a significant impairment for affected individuals, systematic st
Neural Correlates of Restricted, Repetitive Behaviors in Autism Spectrum Disorders
2014-12-01
Restrictive Repetitive Behaviors in Autism Spectrum Disorder . Authors: T.Q.Nguyen, B...Manoach. Functional Connectivity of the Dorsal Anterior Cingulate Cortex Predicts Restrictive Repetitive Behaviors in Autism Spectrum Disorder We...Introduction: Although restricted , repetitive behaviors (RRBs) are a highly disabling core feature of Autism Spectrum Disorders (ASDs), they
Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease
Wong, Min Ney; Murdoch, Bruce E.; Whelan, Brooke-Mai
2012-01-01
Background: Rapid syllable repetition tasks are commonly used in the assessment of motor speech disorders. However, little is known about the articulatory kinematics during rapid syllable repetition in individuals with Parkinson's disease (PD). Aims: To investigate and compare lingual kinematics during rapid syllable repetition in dysarthric…
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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
Repetitive Elements in Mycoplasma hyopneumoniae Transcriptional Regulation
Cattani, Amanda Malvessi; Siqueira, Franciele Maboni; Guedes, Rafael Lucas Muniz; Schrank, Irene Silveira
2016-01-01
Transcriptional regulation, a multiple-step process, is still poorly understood in the important pig pathogen Mycoplasma hyopneumoniae. Basic motifs like promoters and terminators have already been described, but no other cis-regulatory elements have been found. DNA repeat sequences have been shown to be an interesting potential source of cis-regulatory elements. In this work, a genome-wide search for tandem and palindromic repetitive elements was performed in the intergenic regions of all coding sequences from M. hyopneumoniae strain 7448. Computational analysis demonstrated the presence of 144 tandem repeats and 1,171 palindromic elements. The DNA repeat sequences were distributed within the 5’ upstream regions of 86% of transcriptional units of M. hyopneumoniae strain 7448. Comparative analysis between distinct repetitive sequences found in related mycoplasma genomes demonstrated different percentages of conservation among pathogenic and nonpathogenic strains. qPCR assays revealed differential expression among genes showing variable numbers of repetitive elements. In addition, repeats found in 206 genes already described to be differentially regulated under different culture conditions of M. hyopneumoniae strain 232 showed almost 80% conservation in relation to M. hyopneumoniae strain 7448 repeats. Altogether, these findings suggest a potential regulatory role of tandem and palindromic DNA repeats in the M. hyopneumoniae transcriptional profile. PMID:28005945
Modeling repetitive motions using structured light.
Xu, Yi; Aliaga, Daniel G
2010-01-01
Obtaining models of dynamic 3D objects is an important part of content generation for computer graphics. Numerous methods have been extended from static scenarios to model dynamic scenes. If the states or poses of the dynamic object repeat often during a sequence (but not necessarily periodically), we call such a repetitive motion. There are many objects, such as toys, machines, and humans, undergoing repetitive motions. Our key observation is that when a motion-state repeats, we can sample the scene under the same motion state again but using a different set of parameters; thus, providing more information of each motion state. This enables robustly acquiring dense 3D information difficult for objects with repetitive motions using only simple hardware. After the motion sequence, we group temporally disjoint observations of the same motion state together and produce a smooth space-time reconstruction of the scene. Effectively, the dynamic scene modeling problem is converted to a series of static scene reconstructions, which are easier to tackle. The varying sampling parameters can be, for example, structured-light patterns, illumination directions, and viewpoints resulting in different modeling techniques. Based on this observation, we present an image-based motion-state framework and demonstrate our paradigm using either a synchronized or an unsynchronized structured-light acquisition method.
Repetitive element hypermethylation in multiple sclerosis patients.
Neven, K Y; Piola, M; Angelici, L; Cortini, F; Fenoglio, C; Galimberti, D; Pesatori, A C; Scarpini, E; Bollati, V
2016-06-18
Multiple sclerosis (MS) is a complex disorder of the central nervous system whose cause is currently unknown. Evidence is increasing that DNA methylation alterations could be involved in inflammatory and neurodegenerative diseases and could contribute to MS pathogenesis. Repetitive elements Alu, LINE-1 and SAT-α, are widely known as estimators of global DNA methylation. We investigated Alu, LINE-1 and SAT-α methylation levels to evaluate their difference in a case-control setup and their role as a marker of disability. We obtained blood samples from 51 MS patients and 137 healthy volunteers matched by gender, age and smoking. Methylation was assessed using bisulfite-PCR-pyrosequencing. For all participants, medical history, physical and neurological examinations and screening laboratory tests were collected. All repetitive elements were hypermethylated in MS patients compared to healthy controls. A lower Expanded Disability Status Scale (EDSS) score was associated with a lower levels of LINE-1 methylation for 'EDSS = 1.0' and '1.5 ≤ EDSS ≤ 2.5' compared to an EDSS higher than 3, while Alu was associated with a higher level of methylation in these groups: 'EDSS = 1.0' and '1.5 ≤ EDSS ≤ 2.5'. MS patients exhibit an hypermethylation in repetitive elements compared to healthy controls. Alu and LINE-1 were associated with degree of EDSS score. Forthcoming studies focusing on epigenetics and the multifactorial pathogenetic mechanism of MS could elucidate these links further.
FRB repetition and non-Poissonian statistics
Connor, Liam; Oppermann, Niels
2016-01-01
We discuss some of the claims that have been made regarding the statistics of fast radio bursts (FRBs). In an earlier paper \\citep{2015arXiv150505535C} we conjectured that flicker noise associated with FRB repetition could show up in non-cataclysmic neutron star emission models, like supergiant pulses. We show how the current limits of repetition would be significantly weakened if their repeat rate really were non-Poissonian and had a pink or red spectrum. Repetition and its statistics have implications for observing strategy, generally favouring shallow wide-field surveys, since in the non-repeating scenario survey depth is unimportant. We also discuss the statistics of the apparent latitudinal dependence of FRBs, and offer a simple method for calculating the significance of this effect. We provide a generalized Bayesian framework for addressing this problem, which allows for direct model comparison. It is shown how the evidence for a steep latitudinal gradient of the FRB rate is less strong than initially s...
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.
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.
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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%.
Static and dynamic tensile behaviour of aluminium processed by high pressure torsion
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
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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.
A discussion on the most general torsion-gravity with electrodynamics for Dirac spinor matter fields
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.
Multidimensional Seismic Control by Tuned Mass Damper with Poles and Torsional Pendulums
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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.
One-stage correction of chordee and 180-degree penile torsion.
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.
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.
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.
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.
Torsional natural frequency tuning by means of pneumatic flexible shaft couplings
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.
Torsional natural frequency tuning by means of pneumatic flexible shaft couplings
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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.
Characteristics of Pneumatic Tuners of Torsional Oscillation as a Result of Patent Activity
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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.
Exciton Localization in Extended π-Electron Systems: Comparison of Linear and Cyclic Structures.
Thiessen, Alexander; Würsch, Dominik; Jester, Stefan-S; Aggarwal, A Vikas; Idelson, Alissa; Bange, Sebastian; Vogelsang, Jan; Höger, Sigurd; Lupton, John M
2015-07-30
We employ five π-conjugated model materials of different molecular shape-oligomers and cyclic structures-to investigate the extent of exciton self-trapping and torsional motion of the molecular framework following optical excitation. Our studies combine steady state and transient fluorescence spectroscopy in the ensemble with measurements of polarization anisotropy on single molecules, supported by Monte Carlo simulations. The dimer exhibits a significant spectral red shift within ∼100 ps after photoexcitation which is attributed to torsional relaxation. This relaxation mechanism is inhibited in the structurally rigid macrocyclic analogue. However, both systems show a high degree of exciton localization but with very different consequences: while, in the macrocycle, the exciton localizes randomly on different parts of the ring, scrambling polarization memory, in the dimer, localization leads to a deterministic exciton position with luminescence characteristics of a dipole. Monte Carlo simulations allow us to quantify the structural difference between the emitting and absorbing units of the π-conjugated system in terms of disorder parameters.
Torsional Ultrasound Sensor Optimization for Soft Tissue Characterization
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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.
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.)
The CFT dual of AdS gravity with torsion
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...