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Sample records for dna relieves torsional

  1. Transport of torsional stress in DNA

    PubMed Central

    Nelson, Philip

    1999-01-01

    It is well known that transcription can induce torsional stress in DNA, affecting the activity of nearby genes or even inducing structural transitions in the DNA duplex. It has long been assumed that the generation of significant torsional stress requires the DNA to be anchored, forming a limited topological domain, because otherwise it would spin almost freely about its axis. Previous estimates of the rotational drag have, however, neglected the role of small natural bends in the helix backbone. We show how these bends can increase the drag several thousandfold relative to prior estimates, allowing significant torsional stress even in linear unanchored DNA. The model helps explain several puzzling experimental results on structural transitions induced by transcription of DNA. PMID:10588707

  2. Unravelling the structural plasticity of stretched DNA under torsional constraint

    NASA Astrophysics Data System (ADS)

    King, Graeme A.; Peterman, Erwin J. G.; Wuite, Gijs J. L.

    2016-06-01

    Regions of the genome are often held under torsional constraint. Nevertheless, the influence of such constraint on DNA-protein interactions during genome metabolism is still poorly understood. Here using a combined optical tweezers and fluorescence microscope, we quantify and explain how torsional constraint influences the structural stability of DNA under applied tension. We provide direct evidence that concomitant basepair melting and helical unwinding can occur in torsionally constrained DNA at forces >~50 pN. This striking result indicates that local changes in linking number can be absorbed by the rest of the DNA duplex. We also present compelling new evidence that an overwound DNA structure (likely P-DNA) is created (alongside underwound structures) at forces >~110 pN. These findings substantiate previous theoretical predictions and highlight a remarkable structural plasticity of torsionally constrained DNA. Such plasticity may be required in vivo to absorb local changes in linking number in DNA held under torsional constraint.

  3. Localized Torsional Tension in the DNA of Human Cells

    NASA Astrophysics Data System (ADS)

    Ljungman, Mats; Hanawalt, Philip C.

    1992-07-01

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

  4. Unravelling the structural plasticity of stretched DNA under torsional constraint

    PubMed Central

    King, Graeme A.; Peterman, Erwin J. G.; Wuite, Gijs J. L.

    2016-01-01

    Regions of the genome are often held under torsional constraint. Nevertheless, the influence of such constraint on DNA–protein interactions during genome metabolism is still poorly understood. Here using a combined optical tweezers and fluorescence microscope, we quantify and explain how torsional constraint influences the structural stability of DNA under applied tension. We provide direct evidence that concomitant basepair melting and helical unwinding can occur in torsionally constrained DNA at forces >∼50 pN. This striking result indicates that local changes in linking number can be absorbed by the rest of the DNA duplex. We also present compelling new evidence that an overwound DNA structure (likely P-DNA) is created (alongside underwound structures) at forces >∼110 pN. These findings substantiate previous theoretical predictions and highlight a remarkable structural plasticity of torsionally constrained DNA. Such plasticity may be required in vivo to absorb local changes in linking number in DNA held under torsional constraint. PMID:27263853

  5. Impact of DNA Twist Accumulation on Progressive Helical Wrapping of Torsionally Constrained DNA

    NASA Astrophysics Data System (ADS)

    Li, Wei; Wang, Peng-Ye; Yan, Jie; Li, Ming

    2012-11-01

    DNA wrapping is an important mechanism for chromosomal DNA packaging in cells and viruses. Previous studies of DNA wrapping have been performed mostly on torsionally unconstrained DNA, while in vivo DNA is often under torsional constraint. In this study, we extend a previously proposed theoretical model for wrapping of torsionally unconstrained DNA to a new model including the contribution of DNA twist energy, which influences DNA wrapping drastically. In particular, due to accumulation of twist energy during DNA wrapping, it predicts a finite amount of DNA that can be wrapped on a helical spool. The predictions of the new model are tested by single-molecule study of DNA wrapping under torsional constraint using magnetic tweezers. The theoretical predictions and the experimental results are consistent with each other and their implications are discussed.

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

    SciTech Connect

    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.

  7. Extension of torsionally stressed DNA by external force.

    PubMed Central

    Vologodskii, A V; Marko, J F

    1997-01-01

    Metropolis Monte Carlo simulation was used to study the elasticity of torsionally stressed double-helical DNA. Equilibrium distributions of DNA conformations for different values of linking deficit, external force, and ionic conditions were simulated using the discrete wormlike chain model. Ionic conditions were specified in terms of DNA effective diameter, i.e., hard-core radius of the model chain. The simulations show that entropic elasticity of the double helix depends on how much it is twisted. For low amounts of twisting (less than about one turn per twist persistence length) the force versus extension is nearly the same as in the completely torsionally relaxed case. For more twisting than this, the molecule starts to supercoil, and there is an increase in the force needed to realize a given extension. For sufficiently large amounts of twist, the entire chain is plectonemically supercoiled at low extensions; a finite force must be applied to obtain any extension at all in this regime. The simulation results agree well with the results of recent micromanipulation experiments. PMID:9199777

  8. Nonlinear effects in the torsional adjustment of interacting DNA

    NASA Astrophysics Data System (ADS)

    Kornyshev, A. A.; Wynveen, A.

    2004-04-01

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

  9. Studies of torsional properties of DNA and nucleosomes using angular optical trapping

    NASA Astrophysics Data System (ADS)

    Sheinin, Maxim Y.

    DNA in vivo is subjected to torsional stress due to the action of molecular motors and other DNA-binding proteins. Several decades of research have uncovered the fascinating diversity of DNA transformations under torsion and the important role they play in the regulation of vital cellular processes such as transcription and replication. Recent studies have also suggested that torsion can influence the structure and stability of nucleosomes---basic building blocks of the eukaryotic genome. However, our understanding of the impact of torsion is far from being complete due to significant experimental challenges. In this work we have used a powerful single-molecule experimental technique, angular optical trapping, to address several long-standing issues in the field of DNA and nucleosome mechanics. First, we utilized the high resolution and direct torque measuring capability of the angular optical trapping to precisely measure DNA twist-stretch coupling. Second, we characterized DNA melting under tension and torsion. We found that torsionally underwound DNA forms a left-handed structure, significantly more flexible compared to the regular B-DNA. Finally, we performed the first comprehensive investigation of the single nucleosome behavior under torque and force. Importantly, we discovered that positive torque causes significant dimer loss, which can have implications for transcription through chromatin.

  10. Fluorescence anisotropy of DNA/DAPI complex: torsional dynamics and geometry of the complex.

    PubMed Central

    Barcellona, M L; Gratton, E

    1996-01-01

    Fluorescence depolarization of synthetic polydeoxynucleotide/4'-6-diamidino-2-phenylindole dihydrochloride complexes has been investigated as a function of dye/polymer coverage. At low coverage, fluorescence depolarization is due to local torsional motions of the DNA segment where the dye resides. At relatively high coverage, fluorescence depolarization is dominated by energy transfer to other dye molecules along the DNA. The extent of the observed depolarization due to torsional motion depends on the angle the dye molecule forms with the DNA helical axis. A large torsional motion and a small angle produce the same depolarization as a small torsional motion and a large projection angle. Furthermore, the extent of transfer critically depends on the relative orientation of dye molecules along the DNA. The effect of multiple transfer is examined using a Monte Carlo approach. The measurement of depolarization with transfer, at high coverage, allows determination of the dye orientation about the DNA helical axis. The value of the torsional spring constant is then determined, at very low coverage, for few selected polydeoxynucleotides. Images FIGURE 3 PMID:9172758

  11. The dynamic response of upstream DNA to transcription-generated torsional stress.

    PubMed

    Kouzine, Fedor; Liu, Juhong; Sanford, Suzanne; Chung, Hye-Jung; Levens, David

    2004-11-01

    The torsional stress caused by counter-rotation of the transcription machinery and template generates supercoils in a closed topological domain, but has been presumed to be too short-lived to be significant in an open domain. This report shows that transcribing RNA polymerases dynamically sustain sufficient torsion to perturb DNA structure even on linear templates. Assays to capture and measure transcriptionally generated torque and to trap short-lived perturbations in DNA structure and conformation showed that the transient forces upstream of active promoters are large enough to drive the supercoil-sensitive far upstream element (FUSE) of the human c-myc into single-stranded DNA. An alternative non-B conformation of FUSE found in stably supercoiled DNA is not accessible dynamically. These results demonstrate that dynamic disturbance of DNA structure provides a real-time measure of ongoing genetic activity.

  12. Torsional regulation of hRPA-induced unwinding of double-stranded DNA.

    PubMed

    De Vlaminck, Iwijn; Vidic, Iztok; van Loenhout, Marijn T J; Kanaar, Roland; Lebbink, Joyce H G; Dekker, Cees

    2010-07-01

    All cellular single-stranded (ss) DNA is rapidly bound and stabilized by single stranded DNA-binding proteins (SSBs). Replication protein A, the main eukaryotic SSB, is able to unwind double-stranded (ds) DNA by binding and stabilizing transiently forming bubbles of ssDNA. Here, we study the dynamics of human RPA (hRPA) activity on topologically constrained dsDNA with single-molecule magnetic tweezers. We find that the hRPA unwinding rate is exponentially dependent on torsion present in the DNA. The unwinding reaction is self-limiting, ultimately removing the driving torsional stress. The process can easily be reverted: release of tension or the application of a rewinding torque leads to protein dissociation and helix rewinding. Based on the force and salt dependence of the in vitro kinetics we anticipate that the unwinding reaction occurs frequently in vivo. We propose that the hRPA unwinding reaction serves to protect and stabilize the dsDNA when it is structurally destabilized by mechanical stresses.

  13. Toward Improved Description of DNA Backbone: Revisiting Epsilon and Zeta Torsion Force Field Parameters

    PubMed Central

    Zgarbová, Marie; Luque, F. Javier; Šponer, Jiří; Cheatham, Thomas E.; Otyepka, Michal; Jurečka, Petr

    2013-01-01

    We present a refinement of the backbone torsion parameters ε and ζ of the Cornell et al. AMBER force field for DNA simulations. The new parameters, denoted as εζOL1, were derived from quantum-mechanical calculations with inclusion of conformation-dependent solvation effects according to the recently reported methodology (J. Chem. Theory Comput. 2012, 7(9), 2886-2902). The performance of the refined parameters was analyzed by means of extended molecular dynamics (MD) simulations for several representative systems. The results showed that the εζOL1 refinement improves the backbone description of B-DNA double helices and G-DNA stem. In B-DNA simulations, we observed an average increase of the helical twist and narrowing of the major groove, thus achieving better agreement with X-ray and solution NMR data. The balance between populations of BI and BII backbone substates was shifted towards the BII state, in better agreement with ensemble-refined solution experimental results. Furthermore, the refined parameters decreased the backbone RMS deviations in B-DNA MD simulations. In the antiparallel guanine quadruplex (G-DNA) the εζOL1 modification improved the description of non-canonical α/γ backbone substates, which were shown to be coupled to the ε/ζ torsion potential. Thus, the refinement is suggested as a possible alternative to the current ε/ζ torsion potential, which may enable more accurate modeling of nucleic acids. However, long-term testing is recommended before its routine application in DNA simulations. PMID:24058302

  14. The conductive properties of single DNA molecules studied by torsion tunneling atomic force microscopy.

    PubMed

    Wang, W; Niu, D X; Jiang, C R; Yang, X J

    2014-01-17

    The conductive properties of single natural λ-DNA molecules are studied by torsion tunneling atomic force microscopy (TR-TUNA). The currents both parallel to and perpendicular to the DNA chains are investigated, but only weak or even no current signals are detected by TR-TUNA. To improve the conductance of DNA molecules, silver and copper metallized DNAs are fabricated and their conductivities are checked by TR-TUNA. It is found that for both Cu- and Ag-DNAs, the conductivity perpendicular to the DNA chain is enhanced significantly as the metal clusters are attached to the DNA chains. But parallel to the chain the electrical transport is still weak, most probably due to the 'beads-on-a-string' constructions of metallized DNAs.

  15. The conductive properties of single DNA molecules studied by torsion tunneling atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Wang, W.; Niu, D. X.; Jiang, C. R.; Yang, X. J.

    2014-01-01

    The conductive properties of single natural λ-DNA molecules are studied by torsion tunneling atomic force microscopy (TR-TUNA). The currents both parallel to and perpendicular to the DNA chains are investigated, but only weak or even no current signals are detected by TR-TUNA. To improve the conductance of DNA molecules, silver and copper metallized DNAs are fabricated and their conductivities are checked by TR-TUNA. It is found that for both Cu- and Ag-DNAs, the conductivity perpendicular to the DNA chain is enhanced significantly as the metal clusters are attached to the DNA chains. But parallel to the chain the electrical transport is still weak, most probably due to the ‘beads-on-a-string’ constructions of metallized DNAs.

  16. Restrained torsional dynamics of nuclear DNA in living proliferative mammalian cells.

    PubMed Central

    Tramier, M; Kemnitz, K; Durieux, C; Coppey, J; Denjean, P; Pansu, R B; Coppey-Moisan, M

    2000-01-01

    Physical parameters, describing the state of chromatinized DNA in living mammalian cells, were revealed by in situ fluorescence dynamic properties of ethidium in its free and intercalated states. The lifetimes and anisotropy decays of this cationic chromophore were measured within the nuclear domain, by using the ultra-sensitive time-correlated single-photon counting technique, confocal microscopy, and ultra-low probe concentrations. We found that, in living cells: 1) free ethidium molecules equilibrate between extracellular milieu and nucleus, demonstrating that the cation is naturally transported into the nucleus; 2) the intercalation of ethidium into chromatinized DNA is strongly inhibited, with relaxation of the inhibition after mild (digitonin) cell treatment; 3) intercalation sites are likely to be located in chromatin DNA; and 4) the fluorescence anisotropy relaxation of intercalated molecules is very slow. The combination of fluorescence kinetic and fluorescence anisotropy dynamics indicates that the torsional dynamics of nuclear DNA is highly restrained in living cells. PMID:10777758

  17. Force and twist dependence of RepC nicking activity on torsionally-constrained DNA molecules

    PubMed Central

    Pastrana, Cesar L.; Carrasco, Carolina; Akhtar, Parvez; Leuba, Sanford H.; Khan, Saleem A.; Moreno-Herrero, Fernando

    2016-01-01

    Many bacterial plasmids replicate by an asymmetric rolling-circle mechanism that requires sequence-specific recognition for initiation, nicking of one of the template DNA strands and unwinding of the duplex prior to subsequent leading strand DNA synthesis. Nicking is performed by a replication-initiation protein (Rep) that directly binds to the plasmid double-stranded origin and remains covalently bound to its substrate 5′-end via a phosphotyrosine linkage. It has been proposed that the inverted DNA sequences at the nick site form a cruciform structure that facilitates DNA cleavage. However, the role of Rep proteins in the formation of this cruciform and the implication for its nicking and religation functions is unclear. Here, we have used magnetic tweezers to directly measure the DNA nicking and religation activities of RepC, the replication initiator protein of plasmid pT181, in plasmid sized and torsionally-constrained linear DNA molecules. Nicking by RepC occurred only in negatively supercoiled DNA and was force- and twist-dependent. Comparison with a type IB topoisomerase in similar experiments highlighted a relatively inefficient religation activity of RepC. Based on the structural modeling of RepC and on our experimental evidence, we propose a model where RepC nicking activity is passive and dependent upon the supercoiling degree of the DNA substrate. PMID:27488190

  18. Could humic acid relieve the biochemical toxicities and DNA damage caused by nickel and deltamethrin in earthworms (Eisenia foetida)?

    PubMed

    Shen, Chen-Chao; Shen, Dong-Sheng; Shentu, Jia-Li; Wang, Mei-Zhen; Wan, Ming-Yang

    2015-12-01

    The aim of the study was to determine whether humic acid (HA) prevented gene and biochemical toxic effects in earthworms (Eisenia foetida) exposed to nickel and deltamethrin (at 100 and 1 mg kg(-1), respectively) in soil. Cellular- and molecular-level toxic effects of nickel and deltamethrin in earthworms were evaluated by measuring damage to lipid membranes and DNA and the production of protein carbonyls over 42 days of exposure. Nickel and deltamethrin induced significant levels of oxidative stress in earthworms, increasing the production of peroxidation products (malondialdehyde and protein carbonyls) and increasing the comet assay tail DNA% (determined by single-cell gel electrophoresis). DNA damage was the most sensitive of the three indices because it gave a higher sample/control ratio than did the other indices. The presence of HA alleviated (in decreasing order of effectiveness) damage to DNA, proteins, and lipid membranes caused by nickel and deltamethrin. A low HA dose (0.5-1% HA in soil) prevented a great deal of lipid membrane damage, but the highest HA dose (3% HA in soil) prevented still more DNA damage. However, the malondialdehyde concentrations in earthworms were higher at the highest HA dose than at the lower HA doses. The amounts of protein carbonyls produced at different HA doses were not significantly different. The toxic effects to earthworms caused by increased oxidizable nickel concentrations could be relieved by adding HA.

  19. How topoisomerase IV can efficiently unknot and decatenate negatively supercoiled DNA molecules without causing their torsional relaxation.

    PubMed

    Rawdon, Eric J; Dorier, Julien; Racko, Dusan; Millett, Kenneth C; Stasiak, Andrzej

    2016-06-02

    Freshly replicated DNA molecules initially form multiply interlinked right-handed catenanes. In bacteria, these catenated molecules become supercoiled by DNA gyrase before they undergo a complete decatenation by topoisomerase IV (Topo IV). Topo IV is also involved in the unknotting of supercoiled DNA molecules. Using Metropolis Monte Carlo simulations, we investigate the shapes of supercoiled DNA molecules that are either knotted or catenated. We are especially interested in understanding how Topo IV can unknot right-handed knots and decatenate right-handed catenanes without acting on right-handed plectonemes in negatively supercoiled DNA molecules. To this end, we investigate how the topological consequences of intersegmental passages depend on the geometry of the DNA-DNA juxtapositions at which these passages occur. We observe that there are interesting differences between the geometries of DNA-DNA juxtapositions in the interwound portions and in the knotted or catenated portions of the studied molecules. In particular, in negatively supercoiled, multiply interlinked, right-handed catenanes, we detect specific regions where DNA segments belonging to two freshly replicated sister DNA molecules form left-handed crossings. We propose that, due to its geometrical preference to act on left-handed crossings, Topo IV can specifically unknot supercoiled DNA, as well as decatenate postreplicative catenanes, without causing their torsional relaxation.

  20. How topoisomerase IV can efficiently unknot and decatenate negatively supercoiled DNA molecules without causing their torsional relaxation

    PubMed Central

    Rawdon, Eric J.; Dorier, Julien; Racko, Dusan; Millett, Kenneth C.; Stasiak, Andrzej

    2016-01-01

    Freshly replicated DNA molecules initially form multiply interlinked right-handed catenanes. In bacteria, these catenated molecules become supercoiled by DNA gyrase before they undergo a complete decatenation by topoisomerase IV (Topo IV). Topo IV is also involved in the unknotting of supercoiled DNA molecules. Using Metropolis Monte Carlo simulations, we investigate the shapes of supercoiled DNA molecules that are either knotted or catenated. We are especially interested in understanding how Topo IV can unknot right-handed knots and decatenate right-handed catenanes without acting on right-handed plectonemes in negatively supercoiled DNA molecules. To this end, we investigate how the topological consequences of intersegmental passages depend on the geometry of the DNA-DNA juxtapositions at which these passages occur. We observe that there are interesting differences between the geometries of DNA-DNA juxtapositions in the interwound portions and in the knotted or catenated portions of the studied molecules. In particular, in negatively supercoiled, multiply interlinked, right-handed catenanes, we detect specific regions where DNA segments belonging to two freshly replicated sister DNA molecules form left-handed crossings. We propose that, due to its geometrical preference to act on left-handed crossings, Topo IV can specifically unknot supercoiled DNA, as well as decatenate postreplicative catenanes, without causing their torsional relaxation. PMID:27106058

  1. Crossover-site sequence and DNA torsional stress control strand interchanges by the Bxb1 site-specific serine recombinase

    PubMed Central

    Keenholtz, Ross A.; Grindley, Nigel D.F.; Hatfull, Graham F.; Marko, John F.

    2016-01-01

    DNA segment exchange by site-specific serine recombinases (SRs) is thought to proceed by rigid-body rotation of the two halves of the synaptic complex, following the cleavages that create the two pairs of exchangeable ends. It remains unresolved how the amount of rotation occurring between cleavage and religation is controlled. We report single-DNA experiments for Bxb1 integrase, a model SR, where dynamics of individual synapses were observed, using relaxation of supercoiling to report on cleavage and rotation events. Relaxation events often consist of multiple rotations, with the number of rotations per relaxation event and rotation velocity sensitive to DNA sequence at the center of the recombination crossover site, torsional stress and salt concentration. Bulk and single-DNA experiments indicate that the thermodynamic stability of the annealed, but cleaved, crossover sites controls ligation efficiency of recombinant and parental synaptic complexes, regulating the number of rotations during a breakage-religation cycle. The outcome is consistent with a ‘controlled rotation’ model analogous to that observed for type IB topoisomerases, with religation probability varying in accord with DNA base-pairing free energies at the crossover site. Significantly, we find no evidence for a special regulatory mechanism favoring ligation and product release after a single 180° rotation. PMID:27550179

  2. Testicular Torsion

    MedlinePlus

    ... Journal of Urology. 2011;185:2469. Hittelman AB. Neonatal testicular torsion. http://www.uptodate.com/home. Accessed ... 16, 2015. Snyder HM, et al. In utero/neonatal torsion: Observation versus prompt exploration. Journal of Urology. ...

  3. Ursolic Acid-Regulated Energy Metabolism—Reliever or Propeller of Ultraviolet-Induced Oxidative Stress and DNA Damage?

    PubMed Central

    Lee, Yuan-Hao; Sun, Youping; Glickman, Randolph D.

    2014-01-01

    Ultraviolet (UV) light is a leading cause of diseases, such as skin cancers and cataracts. A main process mediating UV-induced pathogenesis is the production of reactive oxygen species (ROS). Excessive ROS levels induce the formation of DNA adducts (e.g., pyrimidine dimers) and result in stalled DNA replication forks. In addition, ROS promotes phosphorylation of tyrosine kinase-coupled hormone receptors and alters downstream energy metabolism. With respect to the risk of UV-induced photocarcinogenesis and photodamage, the antitumoral and antioxidant functions of natural compounds become important for reducing UV-induced adverse effects. One important question in the field is what determines the differential sensitivity of various types of cells to UV light and how exogenous molecules, such as phytochemicals, protect normal cells from UV-inflicted damage while potentiating tumor cell death, presumably via interaction with intracellular target molecules and signaling pathways. Several endogenous molecules have emerged as possible players mediating UV-triggered DNA damage responses. Specifically, UV activates the PIKK (phosphatidylinositol 3-kinase-related kinase) family members, which include DNA-PKcs, ATM (ataxia telangiectasia mutated) and mTOR (mammalian target of rapamycin), whose signaling can be affected by energy metabolism; however, it remains unclear to what extent the activation of hormone receptors regulates PIKKs and whether this crosstalk occurs in all types of cells in response to UV. This review focuses on proteomic descriptions of the relationships between cellular photosensitivity and the phenotypic expression of the insulin/insulin-like growth receptor. It covers the cAMP-dependent pathways, which have recently been shown to regulate the DNA repair machinery through interactions with the PIKK family members. Finally, this review provides a strategic illustration of how UV-induced mitogenic activity is modulated by the insulin sensitizer, ursolic

  4. SENP7 Potentiates cGAS Activation by Relieving SUMO-Mediated Inhibition of Cytosolic DNA Sensing

    PubMed Central

    Cui, Ye; Yu, Huansha; Zheng, Xin; Peng, Rui; Wang, Qiang; Zhou, Yi; Wang, Rui; Wang, Jiehua; Qu, Bo; Shen, Nan; Guo, Qiang; Liu, Xing; Wang, Chen

    2017-01-01

    Cyclic GMP-AMP (cGAMP) synthase (cGAS, a.k.a. MB21D1), a cytosolic DNA sensor, catalyzes formation of the second messenger 2’3’-cGAMP that activates the stimulator of interferon genes (STING) signaling. How the cGAS activity is modulated remains largely unknown. Here, we demonstrate that sentrin/SUMO-specific protease 7 (SENP7) interacted with and potentiated cGAS activation. The small ubiquitin-like modifier (SUMO) was conjugated onto the lysine residues 335, 372 and 382 of cGAS, which suppressed its DNA-binding, oligomerization and nucleotidyl-transferase activities. SENP7 reversed this inhibition via catalyzing the cGAS de-SUMOylation. Consistently, silencing of SENP7 markedly impaired the IRF3-responsive gene expression induced by cGAS-STING axis. SENP7-knockdown mice were more susceptible to herpes simplex virus 1 (HSV-1) infection. SENP7 was significantly up-regulated in patients with SLE. Our study highlights the temporal modulation of the cGAS activity via dynamic SUMOylation, uncovering a novel mechanism for fine-tuning the STING signaling in innate immunity. PMID:28095500

  5. Testicular torsion.

    PubMed

    Ringdahl, Erika; Teague, Lynn

    2006-11-15

    Each year, testicular torsion affects one in 4,000 males younger than 25 years. Early diagnosis and definitive management are the keys to avoid testicular loss. All prepubertal and young adult males with acute scrotal pain should be considered to have testicular torsion until proven otherwise. The finding of an ipsilateral absent cremasteric reflex is the most accurate sign of testicular torsion. Torsion of the appendix testis is more common in children than testicular torsion and may be diagnosed by the "blue dot sign" (i.e., tender nodule with blue discoloration on the upper pole of the testis). Epididymitis/orchitis is much less common in the prepubertal male, and the diagnosis should be made with caution in this age group. Doppler ultrasonography may be needed for definitive diagnosis; radionuclide scintigraphy is an alternative that may be more accurate but should be ordered only if it can be performed without delay. Diagnosis of testicular torsion is based on the finding of decreased or absent blood flow on the ipsilateral side. Treatment involves rapid restoration of blood flow to the affected testis. The optimal time frame is less than six hours after the onset of symptoms. Manual detorsion by external rotation of the testis can be successful, but restoration of blood flow must be confirmed following the maneuver. Surgical exploration provides definitive treatment for the affected testis by orchiopexy and allows for prophylactic orchiopexy of the contralateral testis. Surgical treatment of torsion of the appendix testis is not mandatory but hastens recovery.

  6. Terminal differentiation of cardiac and skeletal myocytes induces permissivity to AAV transduction by relieving inhibition imposed by DNA damage response proteins.

    PubMed

    Lovric, Jasmina; Mano, Miguel; Zentilin, Lorena; Eulalio, Ana; Zacchigna, Serena; Giacca, Mauro

    2012-11-01

    Gene therapy vectors based on the adeno-associated virus (AAV) are extremely efficient for gene transfer into post-mitotic cells of heart, muscle, brain, and retina. The reason for their exquisite tropism for these cells has long remained elusive. Here, we show that upon terminal differentiation, cardiac and skeletal myocytes downregulate proteins of the DNA damage response (DDR) and that this markedly induces permissivity to AAV transduction. We observed that expression of members of the MRN complex (Mre11, Rad50, Nbs1), which bind the incoming AAV genomes, faded in cardiomyocytes at ~2 weeks after birth, as well as upon myoblast differentiation in vitro; in both cases, withdrawal of the cells from the cell cycle coincided with increased AAV permissivity. Treatment of proliferating cells with short-interfering RNAs (siRNAs) against the MRN proteins, or with microRNA-24, which is normally upregulated upon terminal differentiation and negatively controls the Nbs1 levels, significantly increased permissivity to AAV transduction. Consistently, delivery of these small RNAs to the juvenile liver concomitant with AAV markedly improved in vivo hepatocyte transduction. Collectively, these findings support the conclusion that cellular DDR proteins inhibit AAV transduction and that terminal cell differentiation relieves this restriction.

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

    SciTech Connect

    Hingerty, B.E.

    1992-07-01

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

  8. Torsional locomotion

    PubMed Central

    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

  9. Pediatric Testicular Torsion.

    PubMed

    Bowlin, Paul R; Gatti, John M; Murphy, J Patrick

    2017-02-01

    The pediatric patient presenting with acute scrotal pain requires prompt evaluation and management given the likelihood of testicular torsion as the underlying cause. Although other diagnoses can present with acute testicular pain, it is important to recognize the possibility of testicular torsion because the best chance of testicular preservation occurs with expeditious management. When testicular torsion is suspected, prompt surgical exploration is warranted. A delay in surgical management should not occur in an effort to obtain confirmatory imaging. When torsion is discovered, the contralateral testicle should undergo fixation to reduce the risk of asynchronous torsion.

  10. miR-155 activates cytokine gene expression in Th17 cells by regulating the DNA-binding protein Jarid2 to relieve polycomb-mediated repression.

    PubMed

    Escobar, Thelma M; Kanellopoulou, Chrysi; Kugler, David G; Kilaru, Gokhul; Nguyen, Cuong K; Nagarajan, Vijayaraj; Bhairavabhotla, Ravikiran K; Northrup, Daniel; Zahr, Rami; Burr, Patrick; Liu, Xiuhuai; Zhao, Keji; Sher, Alan; Jankovic, Dragana; Zhu, Jinfang; Muljo, Stefan A

    2014-06-19

    Specification of the T helper 17 (Th17) cell lineage requires a well-defined set of transcription factors, but how these integrate with posttranscriptional and epigenetic programs to regulate gene expression is poorly understood. Here we found defective Th17 cell cytokine expression in miR-155-deficient CD4+ T cells in vitro and in vivo. Mir155 was bound by Th17 cell transcription factors and was highly expressed during Th17 cell differentiation. miR-155-deficient Th17 and T regulatory (Treg) cells expressed increased amounts of Jarid2, a DNA-binding protein that recruits the Polycomb Repressive Complex 2 (PRC2) to chromatin. PRC2 binding to chromatin and H3K27 histone methylation was increased in miR-155-deficient cells, coinciding with failure to express Il22, Il10, Il9, and Atf3. Defects in Th17 cell cytokine expression and Treg cell homeostasis in the absence of Mir155 could be partially suppressed by Jarid2 deletion. Thus, miR-155 contributes to Th17 cell function by suppressing the inhibitory effects of Jarid2.

  11. miR-155 activates cytokine gene expression in Th17 cells by regulating the DNA-binding protein Jarid2 to relieve Polycomb-mediated repression

    PubMed Central

    Escobar, Thelma M.; Kanellopoulou, Chrysi; Kugler, David G.; Kilaru, Gokhul; Nguyen, Cuong K.; Nagarajan, Vijayaraj; Bhairavabhotla, Ravikiran K.; Northrup, Daniel; Zahr, Rami; Burr, Patrick; Liu, Xiuhuai; Zhao, Keji; Sher, Alan; Jankovic, Dragana; Zhu, Jinfang; Muljo, Stefan A.

    2014-01-01

    Specification of the T helper 17 (Th17) cell lineage requires a well defined set of transcription factors, but how these integrate with post-transcriptional and epigenetic programs to regulate gene expression is poorly understood. Here we found defective Th17 cell cytokine expression in miR-155-deficient CD4+ T cells in vitro and in vivo. Mir155 was bound by Th17 cell transcription factors and was highly expressed during Th17 cell differentiation. miR-155-deficient-Th17 and -T regulatory (Treg) cells expressed increased amounts of Jarid2, a DNA-binding protein that recruits the Polycomb Repressive Complex 2 (PRC2) to chromatin. PRC2 binding to chromatin and H3K27 histone methylation was increased in miR-155-deficient cells, coinciding with failure to express Il22, Il10, Il9 and Atf3. Defects in Th17 cell cytokine expression and Treg cell homeostasis in the absence of Mir155 could be partially suppressed by Jarid2 deletion. Thus, miR-155 contributes to Th17 cell function by suppressing the inhibitory effects of Jarid2. PMID:24856900

  12. Distinguishing the roles of Topoisomerases I and II in relief of transcription-induced torsional stress in yeast rRNA genes.

    PubMed

    French, Sarah L; Sikes, Martha L; Hontz, Robert D; Osheim, Yvonne N; Lambert, Tashima E; El Hage, Aziz; Smith, Mitchell M; Tollervey, David; Smith, Jeffrey S; Beyer, Ann L

    2011-02-01

    To better understand the role of topoisomerase activity in relieving transcription-induced supercoiling, yeast genes encoding rRNA were visualized in cells deficient for either or both of the two major topoisomerases. In the absence of both topoisomerase I (Top1) and topoisomerase II (Top2) activity, processivity was severely impaired and polymerases were unable to transcribe through the 6.7-kb gene. Loss of Top1 resulted in increased negative superhelical density (two to six times the normal value) in a significant subset of rRNA genes, as manifested by regions of DNA template melting. The observed DNA bubbles were not R-loops and did not block polymerase movement, since genes with DNA template melting showed no evidence of slowed elongation. Inactivation of Top2, however, resulted in characteristic signs of slowed elongation in rRNA genes, suggesting that Top2 alleviates transcription-induced positive supercoiling. Together, the data indicate that torsion in front of and behind transcribing polymerase I has different consequences and different resolution. Positive torsion in front of the polymerase induces supercoiling (writhe) and is largely resolved by Top2. Negative torsion behind the polymerase induces DNA strand separation and is largely resolved by Top1.

  13. Cyclic torsion testing

    NASA Technical Reports Server (NTRS)

    Leese, G. E.

    1984-01-01

    Torsional fatigue testing and data analysis procedures are described. Since there are no standards governing cyclic torsion testing that are generally accepted on a widespread basis by the technical community, the different approaches that dominate current experimental activity, and the ramifications of each are discussed. Particular attention is given to the theoretical and experimental difficulties that have paced refinement and general acceptance of test procedures. Finally, specific quantities and nomenclature modelled after analagous axial fatigue properties are suggested as an effective way to communicate torsional fatigue results until accepted standards are established.

  14. Affine dynamics with torsion

    NASA Astrophysics Data System (ADS)

    Gültekin, Kemal

    2016-03-01

    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 Schrödinger, 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.

  15. [Adnexal torsion: three cases].

    PubMed

    Sánez, Henry Aristóteles Mateo; Taboada-Pérez, Grecia Carolina; Hernández-Arroyo, Lysandra; Mateo-Madrigal, Melissa; Mateo-Madrigal, Victoria

    2013-05-01

    Adnexal torsion is a gynecological emergency caused by the torsion of the ovary over its pedicle producing lymphatic and venous stasis, later it develops into ischemia and necrosis, when is not treated. Until recently, the treatment for adnexal torsion has been adnexectomy. This paper report three cases treated successfully with conservative treatment. It is essential to establish a protocol for adnexal torsion management where radical treatments are abandoned and conservative surgeries, such as detorsion and plication, are performed. We suggest as a first choice management adnexal detorsion, in case malignity is suspected to have intraoperative pathologic analysis, and based on the results to decide to preserve the adnexal or remove it for definitive cure.

  16. Testicular Torsion (For Parents)

    MedlinePlus

    ... ON THIS TOPIC Hernias Ultrasound: Scrotum Undescended Testicles Male Reproductive System PQ: I have a lump on one of ... How to Perform a Testicular Self-Examination Varicocele Male Reproductive System Testicular Torsion Contact Us Print Resources Send to ...

  17. How Do Pain Relievers Work? (For Kids)

    MedlinePlus

    ... two pain relievers kids take most often are ibuprofen (say: i-byoo-PRO-fen) and acetaminophen (say: ... away! When you take a pain reliever like ibuprofen, it keeps injured or damaged cells from making ...

  18. How Do Pain Relievers Work? (For Kids)

    MedlinePlus

    ... Dictionary of Medical Words En Español What Other Kids Are Reading Taking Care of Your Ears Taking ... ray How Do Pain Relievers Work? KidsHealth > For Kids > How Do Pain Relievers Work? Print A A ...

  19. Health Hints: Use Caution with Pain Relievers

    MedlinePlus

    ... Resources for You Health Hints: Use Caution with Pain Relievers. Share Tweet Linkedin Pin it More sharing options ... Pin it Email Print PDF version (447KB) (NAPS) -- Pain relievers, when used correctly, are safe and effective. Millions ...

  20. Testicular Torsion (For Parents)

    MedlinePlus

    ... damaged. As a general rule: within about 4-6 hours of the start of the torsion, the testicle can be saved 90% of the time after 12 hours, this drops to 50% after 24 hours, the testicle can be saved only 10% ...

  1. Planar torsion spring

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Parsons, Adam H. (Inventor); Mehling, Joshua S. (Inventor); Griffith, Bryan Kristian (Inventor)

    2012-01-01

    A torsion spring comprises an inner mounting segment. An outer mounting segment is located concentrically around the inner mounting segment. A plurality of splines extends from the inner mounting segment to the outer mounting segment. At least a portion of each spline extends generally annularly around the inner mounting segment.

  2. Spin on perinatal testicular torsion.

    PubMed

    Samnakay, Naeem; Tudehope, David; Walker, Rosslyn

    2006-11-01

    We describe a recent case of perinatal testicular torsion at our institution. The presentation, management and outcome of perinatal testicular torsion are quite different to testicular torsion in the general paediatric population. The literature describes a variety of management options for perinatal testicular torsion and these are briefly reviewed. In cases of unilateral perinatal testicular torsin, there is controversy over whether surgery to fix the contralateral testis is required, and if so, the appropriate timing for the surgery. A good understanding of the issues unique to perinatal torsion will facilitate appropriate counseling of parents of affected neonates.

  3. Nonlinear Hysteretic Torsional Waves

    NASA Astrophysics Data System (ADS)

    Cabaret, J.; Béquin, P.; Theocharis, G.; Andreev, V.; Gusev, V. E.; Tournat, V.

    2015-07-01

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

  4. Nonlinear Hysteretic Torsional Waves.

    PubMed

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

    2015-07-31

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

  5. Torsion of wandering spleen.

    PubMed

    Dirican, A; Burak, I; Ara, C; Unal, B; Ozgor, D; Meydanli, M M

    2009-01-01

    Wandering spleen is characterized by ectopic localization of spleen owing to the lack or weakening of the major splenic ligaments. In present study, two cases with torsion of wandering spleen were reported. The first case was a 30-year-old female who was admitted to emergency department with acute abdominal pain and vomiting. Abdominal Ultrasonography and computed tomography showed a round solid hypodense mass that was located in the left hypochondriac region of abdomen. At laparotomy, the patient was found to have torsion of a wandering spleen with complete infarction and pancreatic tail infarction. Splenectomy and distal pancreatectomy were performed. The second patient was a 19-year-old female. She was admitted to emergency department with abdominal pain. Axial computed tomography (CT) showed pelvic mass that indicated a possibility of a wandering spleen. The wandering spleen was removed with its long pedicle because of infarction. Torsion of wandering spleen must be considered in differential diagnosis of acute abdomen when a palpable painful abdominal mass is present on physical examination, and the spleen is absent in its normal anatomical location on radiological examination (Fig. 4, Ref. 8). Full Text (Free, PDF) www.bmj.sk.

  6. Torsion effects in braneworld scenarios

    SciTech Connect

    Hoff da Silva, J. M.; Rocha, R. da

    2010-01-15

    We present gravitational aspects of braneworld models endowed with torsion terms both in the bulk and on the brane. In order to investigate a conceivable and measurable gravitational effect, arising genuinely from bulk torsion terms, we analyze the variation in the black hole area by the presence of torsion. Furthermore, we extend the well-known results about consistency conditions in a framework that incorporates brane torsion terms. It is shown, in a rough estimate, that the resulting effects are generally suppressed by the internal space volume. This formalism provides manageable models and their possible ramifications into some aspects of gravity in this context, and cognizable corrections and physical effects as well.

  7. Pain Relievers: MedlinePlus Health Topic

    MedlinePlus

    ... to a pain reliever. Over-the-counter (OTC) medicines are good for many types of pain. There are two main types of OTC pain medicines: acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs (NSAIDs). ...

  8. Torsion of Accessory Hepatic Lobe

    PubMed Central

    Natarajan, Saravanan; Jayasudha; Periasamy, Manikandhan; Rangasamy, Saminathan

    2017-01-01

    An accessory hepatic lobe is a rare congenital anomaly that can undergo torsion and present as an acute surgical emergency. A 5-year-old child admitted as acute abdomen, on laparotomy found to have torsion of accessory lobe of liver, is being reported. PMID:28082782

  9. Axions in gravity with torsion

    NASA Astrophysics Data System (ADS)

    Castillo-Felisola, Oscar; Corral, Cristóbal; Kovalenko, Sergey; Schmidt, Iván; Lyubovitskij, Valery E.

    2015-04-01

    We study a scenario allowing a solution of the strong charge parity problem via the Peccei-Quinn mechanism, implemented in gravity with torsion. In this framework there appears a torsion-related pseudoscalar field known as the Kalb-Ramond axion. We compare it with the so-called Barbero-Immirzi axion recently proposed in the literature also in the context of the gravity with torsion. We show that they are equivalent from the viewpoint of the effective theory. The phenomenology of these torsion-descended axions is completely determined by the Planck scale without any additional model parameters. These axions are very light and very weakly interacting with ordinary matter. We briefly comment on their astrophysical and cosmological implications in view of the recent BICEP2 and Planck data.

  10. Inverse problems for torsional modes.

    USGS Publications Warehouse

    Willis, C.

    1984-01-01

    Considers a spherically symmetric, non-rotating Earth consisting of an isotropic, perfect elastic material where the density and the S-wave velocity may have one or two discontinuities in the upper mantle. Shows that given the velocity throughout the mantle and the crust and given the density in the lower mantle, then the freqencies of the torsional oscillations of one angular order (one torsional spectrum), determine the density in the upper mantle and in the crust uniquely. If the velocity is known only in the lower mantle, then the frequencies of the torsional oscillations of two angular orders uniquely determine both the density and the velocity in the upper mantle and in the crust. In particular, the position and size of the discontinuities in the density and velocity are uniquely determined by two torsional spectra.-Author

  11. Isolated penile torsion in newborns

    PubMed Central

    Eroglu, Egemen; Gundogdu, Gokhan

    2015-01-01

    Introduction: We reported on the incidence of isolated penile torsion among our healthy children and our approach to this anomaly. Methods: Between 2011 and 2014, newborn babies with penile torsion were classified according to the angle of torsion. Surgical correction (penile degloving and reattachment for moderate cases and dorsal dartos flap technique in case of resistance) after 6 months was advised to the babies with rotations more than 45°. Results: Among 1000 newborn babies, 200 isolated penile torsions were found, and among these, 43 had torsions more than 45°, and 4 of these had angles greater than 90°. The mean angle of the rotations was found 30.45° (median: 20°). In total, 8 children with 60° torsions were previously circumcised. Surgery was performed on 19 patients, with a mean patient age of 12 ± 2 months. Of these 19, 13 babies were corrected with degloving and reattachment. This technique was not enough on the remaining 6 patients; therefore, derotational dorsal dartos flap was added to correct the torsion. After a mean of 15.6 ± 9.8 months, residual penile rotation, less than 15°, was found only in 2 children. Conclusion: The incidence of isolated penile torsion is 20% in newborns. However, rotation more than 45° angles are seen in 4.3% of male babies. Correction is not necessary in mild degrees, and penile degloving with reattachment is enough in most cases. If the initial correction is insufficient, dorsal dartos flap rotation is easy and effective. Prior circumcision neither disturbs the operative procedure nor affects the outcomes. PMID:26600889

  12. Jacketed cryogenic piping is stress relieved

    NASA Technical Reports Server (NTRS)

    Bowers, W. M.

    1967-01-01

    Jacketed design of piping used to transfer cryogenic fluids, relieves severe stresses associated with the temperature gradients that occur during transfer cycles and ambient periods. The inner /transfer/ pipe is preloaded in such a way that stress relief takes place automatically as cycling occurs.

  13. Topical Pain Relievers May Cause Burns

    MedlinePlus

    ... Reported Cases According to FDA chemist Reynold Tan, Ph.D., there have been 43 reported cases of burns associated with the use of OTC topical muscle and joint pain relievers containing the active ingredients menthol, methyl salicylate and capsaicin. These cases ...

  14. Protective effect of thymoquinone against testicular torsion induced oxidative injury.

    PubMed

    Ayan, M; Tas, U; Sogut, E; Caylı, S; Kaya, H; Esen, M; Erdemir, F; Uysal, M

    2016-03-01

    We aimed to determine the protective effects of thymoquinone (TQ), against ischaemia-reperfusion (I/R) injury in the testis tissue of rats. Twenty-seven male Wistar albino rats were randomly divided into three equal groups as follows: Group I, sham group; Group II, torsion group; and Group III, torsion + thymoquinone group. The ischaemia period was 2 h, and orchiectomy was performed after 30 min of detorsion. Testis tissue sections were analysed with the terminal transferase mediated dUTP-nick end labelling (TUNEL) assay to determine in situ apoptotic DNA fragmentation. Additionally, Caspase 3 and Bax proteins were analysed immunohistochemically. The superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) activity levels in the testis tissue were also measured. The superoxide dismutase activity and malondialdehyde levels in the torsion group were significantly higher than those of the sham group (P < 0.05). Thymoquinone administration significantly reduced these levels. Torsion significantly increased active-Caspase 3 and Bax expression, which was decreased by thymoquinone. The apoptotic index of the torsion group was significantly higher than that of the control group. However, thymoquinone significantly reduced the apoptotic index (P < 0.05). Our results indicate that thymoquinone plays a protective role in oxidative stress induced ischaemia-reperfusion in the testis tissue of rats.

  15. Evidence that processing of ribonucleotides in DNA by topoisomerase 1 is leading-strand specific.

    PubMed

    Williams, Jessica S; Clausen, Anders R; Lujan, Scott A; Marjavaara, Lisette; Clark, Alan B; Burgers, Peter M; Chabes, Andrei; Kunkel, Thomas A

    2015-04-01

    Ribonucleotides incorporated during DNA replication are removed by RNase H2-dependent ribonucleotide excision repair (RER). In RER-defective yeast, topoisomerase 1 (Top1) incises DNA at unrepaired ribonucleotides, initiating their removal, but this is accompanied by RNA-DNA-damage phenotypes. Here we show that these phenotypes are incurred by a high level of ribonucleotides incorporated by a leading strand-replicase variant, DNA polymerase (Pol) ɛ, but not by orthologous variants of the lagging-strand replicases, Pols α or δ. Moreover, loss of both RNases H1 and H2 is lethal in combination with increased ribonucleotide incorporation by Pol ɛ but not by Pols α or δ. Several explanations for this asymmetry are considered, including the idea that Top1 incision at ribonucleotides relieves torsional stress in the nascent leading strand but not in the nascent lagging strand, in which preexisting nicks prevent the accumulation of superhelical tension.

  16. Propagating torsion in the Einstein frame

    NASA Astrophysics Data System (ADS)

    Popławski, Nikodem J.

    2006-11-01

    The Einstein-Cartan-Saa theory of torsion modifies the spacetime volume element so that it is compatible with the connection. The condition of connection compatibility gives constraints on torsion, which are also necessary for the consistence of torsion, minimal coupling, and electromagnetic gauge invariance. To solve the problem of positivity of energy associated with the torsionic scalar, we reformulate this theory in the Einstein conformal frame. In the presence of the electromagnetic field, we obtain the Hojman-Rosenbaum-Ryan-Shepley theory of propagating torsion with a different factor in the torsionic kinetic term.

  17. Pain Relievers - Multiple Languages: MedlinePlus

    MedlinePlus

    ... List of All Topics All Pain Relievers - Multiple Languages To use the sharing features on this page, please enable JavaScript. Chinese - Traditional (繁體中文) French (français) Japanese (日本語) Korean (한국어) Russian (Русский) Somali (af Soomaali) Spanish (español) Ukrainian (Українська) ...

  18. Constraining torsion with Gravity Probe B

    SciTech Connect

    Mao Yi; Guth, Alan H.; Cabi, Serkan; Tegmark, Max

    2007-11-15

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

  19. Torsional carbon nanotube artificial muscles.

    PubMed

    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

    2011-10-28

    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.

  20. Torsional Carbon Nanotube Artificial Muscles

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  1. Torsional rigidity, isospectrality and quantum graphs

    NASA Astrophysics Data System (ADS)

    Colladay, Don; Kaganovskiy, Leon; McDonald, Patrick

    2017-01-01

    We study torsional rigidity for graph and quantum graph analogs of well-known pairs of isospectral non-isometric planar domains. We prove that such isospectral pairs are distinguished by torsional rigidity.

  2. Wandering spleen with chronic torsion.

    PubMed

    Misawa, Takeyuki; Yoshida, Kazuhiko; Shiba, Hiroaki; Kobayashi, Susumu; Yanaga, Katsuhiko

    2008-04-01

    Wandering spleen, a rare clinical entity with a high incidence of splenic torsion and infarction, was preoperatively diagnosed in a 28-year-old woman. Axial computed tomography showed the absence of the spleen in the left subphrenic space and a spleen-like mass in the pelvis, suggestive of a wandering spleen. A coronal contrast-enhanced computed tomography image exhibited the enlarged spleen suspended by elongated, dilated, and somewhat tortuous splenic vessels. Owing to the symptomatic splenomegaly with hypersplenism and chronic torsion, laparoscopic splenectomy was performed.

  3. Torsion of a wandering spleen

    PubMed Central

    Jude, Nwashilli N.; Onochie, Nwajei C.

    2015-01-01

    Wandering spleen is a rare condition that accounts for less than 0.25% of all indications for splenectomy. It is characterized by ectopic localization of the spleen owing to the lack or weakening of its ligaments. Torsion is the most common complication due to its long pedicle and high mobility, which may result in acute abdomen. We report a case of torsion in a wandering spleen in a 28-year-old male presenting with an acute abdomen that was treated by splenectomy. PMID:26620993

  4. Hand-held instrument should relieve hematoma pressure

    NASA Technical Reports Server (NTRS)

    Raggio, L. J.; Robertson, T. L.

    1967-01-01

    Portable instrument relieves hematomas beneath fingernails and toenails without surgery. This device simplifies the operative procedure with an instant variable heating tip, adjustable depth settings and interchangeable tip sizes for cauterizing small areas and relieving pressurized clots.

  5. Torsion Modified Plasma Screening in Astrophysics

    NASA Astrophysics Data System (ADS)

    Sivaram, C.; Garcia de Andrade, L. C.

    The torsion modified Maxwell-Proca equations when applied to describe a plasma is shown to lead to a correction to the Debye screening length. For hot new born neutron stars the torsion correction is shown to be significant. This effect may provide an indirect evidence for torsion.

  6. Pancreatic torsion in a dog

    PubMed Central

    Brabson, Tamera L.; Maki, Lynn C.; Newell, Susan M.; Ralphs, S. Christopher

    2015-01-01

    A 6-month-old male intact Cane Corso mastiff dog was presented for a recent history of vomiting, abdominal pain, and lethargy. A diagnosis of pancreatic torsion was made during abdominal exploratory surgery and was confirmed with histopathology. The dog underwent partial pancreatectomy and recovered with no complications. PMID:25969579

  7. Torsional electromechanical quantum oscillations in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cohen-Karni, Tzahi; Segev, Lior; Srur-Lavi, Onit; Cohen, Sidney R.; Joselevich, Ernesto

    2006-10-01

    Carbon nanotubes can be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multiwalled carbon nanotubes, where both the torque and the current are shown to be carried predominantly by the outermost wall. The oscillation period with torsion is consistent with the theoretical shifting of the corners of the first Brillouin zone of graphene across different sub-bands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Carbon nanotubes could be ideal torsional springs for nanoscopic pendulums, because electromechanical detection of motion could replace the microscopic detection techniques used at present. Our experiments indicate that carbon nanotubes could be used as electronic sensors of torsional motion in nanoelectromechanical systems.

  8. Torsional Split Hopkinson Bar Optimization

    DTIC Science & Technology

    2012-04-10

    is the torsional wave speed . Also, one can relate the torque with the yield stress of the material, as seen in equation 2; where r is the radius of...be equal to the mechanical impedance of the bars. In other words, the product of density, speed of wave and polar moment of inertia must remain...pillow blocks used to mount the incident and transmitter bars are cast iron based- mounted Babbitt-lined bearing split, for 1 in. shaft diameter

  9. Torsion of a wandering spleen.

    PubMed

    El Bouhaddouti, Hicham; Lamrani, Jihane; Louchi, Abdellatif; El Yousfi, Mounia; Aqodad, Noureddine; Ibrahimi, Adil; Boubou, Meriem; Kamaoui, Imane; Tizniti, Siham

    2010-01-01

    Wandering spleen is a rare condition defined as a mobile spleen only attached with its pedicle. It can be complicated by a volvulus, which is a surgical abdominal emergency. Preventing infarction is the aim of a prompt surgery that can preserve the spleen and then proceed to splenopexy. We report a rare case of torsion of a wandering spleen associated with a dolichosigmoοd.

  10. Topological design of torsional metamaterials

    NASA Astrophysics Data System (ADS)

    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.

  11. Les torsions sur testicules cryptorchides

    PubMed Central

    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

  12. Intranatal Torsion of Polydactyly: A Rare Event.

    PubMed

    Gupta, Priyanka; Neogi, Sujoy; Shukla, Amlin; Patwari, A K

    2016-01-01

    Polydactyly is one of the most common anomalies of hand and/or foot. Postnatal torsion of pedunculated polydactyly is a well known complication but intranatal torsion has been infrequently described in published literature. Here, we describe a case of pedunculated ulnar polydactyly which was gangrenous at birth due to intranatal torsion. Controversies surrounding the management of narrow pedicled pedunculated polydactyly by traditional method of suture ligation at base are also discussed.

  13. [A case of neonatal testicular torsion].

    PubMed

    Nishizawa, Satoshi; Nanpo, Yoshihito; Kuramoto, Tomomi; Iba, Akinori; Fujii, Reona; Matsumura, Nagahide; Shintani, Yasuyo; Inagaki, Takeshi; Kohjimoto, Yasuo; Hara, Isao

    2008-12-01

    An infant normally delivered at the 38th week of gestation was referred to our department one day after birth for a firm and painless right hemiscrotal mass with bluish coloration. Since contralateral scrotum showed swelling, we performed emergency surgery on that day. The right spermatic cord was constricted due to extravaginal torsion, and degree and direction of torsion was unclear since the spermatic cord was already organized. Right testis showed irreversible necrotic change, requiring orchiectomy. We confirmed that left testis was intact and performed orchidopexy. Since high incidence of contralateral asymptomatic torsion has been reported in patients with prenatal testicular torsion, emergency surgery should be considered when contralateral scrotum shows abnormal findings.

  14. 46 CFR 58.20-10 - Pressure relieving devices.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Pressure relieving devices. 58.20-10 Section 58.20-10... MACHINERY AND RELATED SYSTEMS Refrigeration Machinery § 58.20-10 Pressure relieving devices. (a) Each pressure vessel containing refrigerants, which may be isolated, shall be protected by a relief valve set...

  15. 46 CFR 58.20-10 - Pressure relieving devices.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Pressure relieving devices. 58.20-10 Section 58.20-10... MACHINERY AND RELATED SYSTEMS Refrigeration Machinery § 58.20-10 Pressure relieving devices. (a) Each pressure vessel containing refrigerants, which may be isolated, shall be protected by a relief valve set...

  16. 46 CFR 58.20-10 - Pressure relieving devices.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Pressure relieving devices. 58.20-10 Section 58.20-10... MACHINERY AND RELATED SYSTEMS Refrigeration Machinery § 58.20-10 Pressure relieving devices. (a) Each pressure vessel containing refrigerants, which may be isolated, shall be protected by a relief valve set...

  17. 46 CFR 58.20-10 - Pressure relieving devices.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Pressure relieving devices. 58.20-10 Section 58.20-10... MACHINERY AND RELATED SYSTEMS Refrigeration Machinery § 58.20-10 Pressure relieving devices. (a) Each pressure vessel containing refrigerants, which may be isolated, shall be protected by a relief valve set...

  18. 46 CFR 58.20-10 - Pressure relieving devices.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Pressure relieving devices. 58.20-10 Section 58.20-10... MACHINERY AND RELATED SYSTEMS Refrigeration Machinery § 58.20-10 Pressure relieving devices. (a) Each pressure vessel containing refrigerants, which may be isolated, shall be protected by a relief valve set...

  19. Bulk micromachined quasistatic torsional micromirror

    NASA Astrophysics Data System (ADS)

    Kiessling, Torsten; Wolter, Alexander; Schenk, Harald; Lakner, Hubert

    2004-01-01

    One dimensional torsional micro mirrors for laser steering applications have been developed and manufactured at Fraunhofer Institute of Photonic Microsystems. Several design variations with rectangular plates are available. The device can be operated in resonant mode and quasistatic mode as well. The device is fabricated out of a BSOI wafer and a second conductive silicon wafer. The structure is assembled by conductive adhesive bonding. Torsional springs connect the mirror plate to the mirror frame mechanically and electrically. Filled isolation trench structures separate volumes of different electrical potentials at the frame and at the deflective mirror respectively. Comb drive structures at both sides of the deflectable mirror and the part of frame located opposite increases capacitance at both mirror half sides. Applying a low level drive voltage between the combs, the mirror can be operated in resonant mode. The second silicon wafer is placed below the deflective mirror and is electrically at ground. Applying a electrical potential of higher level to one side of the deflectable mirror, the mirror can be driven quasistatic and resonant as well. While the drive voltage is applied to one side of the mirror, the comb drive structure of the opposite side can be used for capacitance based position read out.

  20. Inelastic torsion of steel I-beams

    NASA Astrophysics Data System (ADS)

    Pi, Y. L.; Trahair, N. S.

    1993-09-01

    A nonlinear inelastic analysis of the non-uniform torsion of I-section beams is presented in this paper. Large twist rotations are included in the geometry non-linearity. The nonlinear equilibrium equations of beams in nonuniform torsion have been derived and a finite element procedure has been developed based on the analysis. The elastic-plastic behavior of beams in non-uniform torsion is studied using the finite element procedure and the results are compared with tests. It is found that I-section beams have much larger torsional capacities than can be predicted by linear plastic collapse analysis, and that torsional failure occurs not by the formation of a mechanism but by the tensile rupture of the flanges. A method is proposed for calculating the full plastic non-uniform torque for practical design purposes.

  1. Torsional and rotational couplings in nonrigid molecules

    NASA Astrophysics Data System (ADS)

    Omiste, Juan J.; Madsen, Lars Bojer

    2017-02-01

    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 wave packet 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 expectation values of the angular momentum operators for the overall rotation of the molecule.

  2. Optically probing torsional superelasticity in spider silks

    SciTech Connect

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

    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.

  3. Direct measurement of torsional properties of single fibers

    NASA Astrophysics Data System (ADS)

    Liu, Dabiao; Peng, Kai; He, Yuming

    2016-11-01

    In order to characterize the torsional behavior of micron-scale specimens, a direct technique is established based on the principle of torsion balance. The technique applies twist to the specimen and balances the resulting torque against a torsion wire of known torsional rigidity. The torsional rigidity of the torsion wire is determined by a torsion pendulum. To measure the rotation of the torsion wire, a sensitive angle detector, comprising a thin cross-beam attached between the torsion wire and the fiber specimen and a laser displacement sensor, is developed. The presented technique permits the measurement of torque in single fibers as low as 10-9 Nm with a reasonable resolution. Using this technique, torsion tests on micro-diameter copper wires, silver wires and carbon fibers were performed. The longitudinal shear modulus and other torsional properties of these samples, such as yielding shear strength, were obtained.

  4. Thermoelastic damping in torsion microresonators with coupling effect between torsion and bending

    NASA Astrophysics Data System (ADS)

    Tai, Yongpeng; Li, Pu; Fang, Yuming

    2014-02-01

    Predicting thermoelastic damping (TED) is crucial in the design of high Q MEMS resonators. In the past, there have been few works on analytical modeling of thermoelastic damping in torsion microresonators. This could be related to the assumption of pure torsional mode for the supporting beams in the torsion devices. The pure torsional modes of rectangular supporting beams involve no local volume change, and therefore, they do not suffer any thermoelastic loss. However, the coupled motion of torsion and bending usually exists in the torsion microresonator when it is not excited by pure torque. The bending component of the coupled motion causes flexural vibrations of supporting beams which may result in significant thermoelastic damping for the microresonator. This paper presents an analytical model for thermoelastic damping in torsion microresonators with the coupling effect between torsion and bending. The theory derives a dynamic model for torsion microresonators considering the coupling effect, and approximates the thermoelastic damping by assuming the energy loss to occur only in supporting beams of flexural vibrations. The thermoelastic damping obtained by the present model is compared to the measured internal friction of single paddle oscillators. It is found that thermoelastic damping contributes significantly to internal friction for the case of the higher modes at room temperature. The present model is validated by comparing its results with the finite-element method (FEM) solutions. The effects of structural dimensions and other parameters on thermoelastic damping are investigated for the representative case of torsion microresonators.

  5. Magnetic Torsional Oscillations in Magnetars

    SciTech Connect

    Sotani, Hajime; Kokkotas, Kostas D.; Stergioulas, Nikolaos

    2009-05-01

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

  6. New insights into perinatal testicular torsion

    PubMed Central

    Van Kerrebroeck, Philip

    2009-01-01

    Perinatal testicular torsion is a relatively rare event that remains unrecognized in many patients or is suspected and treated accordingly only after an avoidable loss of time. The authors report their own experience with several patients, some of them quite atypical but instructive. Missed bilateral torsion is an issue, as are partial torsion, possible antenatal signs, and late presentation. These data are discussed together with the existing literature and may help shed new light on the natural course of testicular torsion and its treatment. The most important conclusion is that a much higher index of suspicion based on clinical findings is needed for timely detection of perinatal torsion. It is the authors’ opinion that immediate surgery is mandatory not only in suspected bilateral torsions but also in cases of possible unilateral torsions. There is no place for a more fatalistic “wait-and-see” approach. Whenever possible, even necrotic testes should not be removed during surgery because some endocrine function may be retained. PMID:19856186

  7. Nonlinear backbone torsional pair correlations in proteins

    NASA Astrophysics Data System (ADS)

    Long, Shiyang; Tian, Pu

    2016-10-01

    Protein allostery requires dynamical structural correlations. Physical origin of which, however, remain elusive despite intensive studies during last two and half decades. Based on analysis of molecular dynamics (MD) simulation trajectories for ten proteins with different sizes and folds, we found that nonlinear backbone torsional pair (BTP) correlations, which are mainly spatially long-ranged and are dominantly executed by loop residues, exist extensively in most analyzed proteins. Examination of torsional motion for correlated BTPs suggested that such nonlinear correlations are mainly associated aharmonic torsional state transitions and in some cases strongly anisotropic local torsional motion of participating torsions, and occur on widely different and relatively longer time scales. In contrast, correlations between backbone torsions in stable α helices and β strands are mainly linear and spatially short-ranged, and are more likely to associate with harmonic local torsional motion. Further analysis revealed that the direct cause of nonlinear contributions are heterogeneous linear correlations. These findings implicate a general search strategy for novel allosteric modulation sites of protein activities.

  8. Nonlinear backbone torsional pair correlations in proteins

    PubMed Central

    Long, Shiyang; Tian, Pu

    2016-01-01

    Protein allostery requires dynamical structural correlations. Physical origin of which, however, remain elusive despite intensive studies during last two and half decades. Based on analysis of molecular dynamics (MD) simulation trajectories for ten proteins with different sizes and folds, we found that nonlinear backbone torsional pair (BTP) correlations, which are mainly spatially long-ranged and are dominantly executed by loop residues, exist extensively in most analyzed proteins. Examination of torsional motion for correlated BTPs suggested that such nonlinear correlations are mainly associated aharmonic torsional state transitions and in some cases strongly anisotropic local torsional motion of participating torsions, and occur on widely different and relatively longer time scales. In contrast, correlations between backbone torsions in stable α helices and β strands are mainly linear and spatially short-ranged, and are more likely to associate with harmonic local torsional motion. Further analysis revealed that the direct cause of nonlinear contributions are heterogeneous linear correlations. These findings implicate a general search strategy for novel allosteric modulation sites of protein activities. PMID:27708342

  9. Torsional Resonators Based on Inorganic Nanotubes.

    PubMed

    Divon, Yiftach; Levi, Roi; Garel, Jonathan; Golberg, Dmitri; Tenne, Reshef; Ya'akobovitz, Assaf; Joselevich, Ernesto

    2017-01-11

    We study for the first time the resonant torsional behaviors of inorganic nanotubes, specifically tungsten disulfide (WS2) and boron nitride (BN) nanotubes, and compare them to that of carbon nanotubes. We have found WS2 nanotubes to have the highest quality factor (Q) and torsional resonance frequency, followed by BN nanotubes and carbon nanotubes. Dynamic and static torsional spring constants of the various nanotubes were found to be different, especially in the case of WS2, possibly due to a velocity-dependent intershell friction. These results indicate that inorganic nanotubes are promising building blocks for high-Q nanoelectromechanical systems (NEMS).

  10. Modification of gravity due to torsion

    SciTech Connect

    Nair, V. P.; Nikiforova, V.; Randjbar-Daemi, S.; Rubakov, V.

    2010-01-01

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

  11. Torsion of wandering spleen and distal pancreas

    SciTech Connect

    Sheflin, J.R.; Lee, C.M.; Kretchmar, K.A.

    1984-01-01

    Wandering spleen is the term applied to the condition in which a long pedicle allows the spleen to lie in an abnormal location. Torsion of a wandering spleen is an unusual cause of an acute abdomen and is rarely diagnosed preoperatively. Associated torsion of the distal pancreas is even more uncommon. The authors describe a patient with torsion of a wandering spleen and distal pancreas, who was correctly diagnosed, and define the merits of the imaging methods used. The initial examination should be /sup 99//sup m/Tc-sulfur colloid liner-spleen scanning.

  12. Reviewing the Literature on the Effectiveness of Pressure Relieving Movements

    PubMed Central

    Stinson, May

    2013-01-01

    Sitting for prolonged periods of time increases seating interface pressures, which is known to increase the risk of developing pressure ulcers. Those at risk of developing pressure ulcers are advised to perform pressure relieving movements such as “pushups” or “forward leans” in order to reduce the duration and magnitude of pressure acting on the vulnerable ischial tuberosity region. The aim of this review was to synthesize and critique the existing literature investigating the effectiveness of pressure relieving movements on seating interface pressures. The twenty-seven articles included in this paper highlight the need for further research investigating the effect of recommended pressure relieving movements on the pressures around the ischial tuberosities. Furthermore, this review found that the majority of individuals at risk of developing pressure ulcers do not adhere with the pressure relieving frequency or magnitude of movements currently recommended, indicating a need for pressure ulcer prevention to be explored further. PMID:23365733

  13. Halfcellar underneath original house showing fireplace relieving arch at northwest ...

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

    Half-cellar underneath original house showing fireplace relieving arch at northwest end; enclosed "cheese" room to right - Scheetz Farm, House, 7161 Camp Hill Road, Fort Washington, Montgomery County, PA

  14. Torsion-induced effects in magnetic nanowires

    NASA Astrophysics Data System (ADS)

    Sheka, Denis D.; Kravchuk, Volodymyr P.; Yershov, Kostiantyn V.; Gaididei, Yuri

    2015-08-01

    A magnetic helix wire is one of the simplest magnetic systems which manifests properties of both curvature and torsion. Possible equilibrium magnetization states in the helix wire with different anisotropy directions are studied theoretically. There exist two equilibrium states in the helix wire with easy-tangential anisotropy: a quasitangential magnetization distribution in the case of relatively small curvatures and torsions, and an onion state in the opposite case. The curvature and torsion also essentially influence the spin-wave dynamics in the helix wire, acting as an effective magnetic field. Originated from a geometry-induced effective Dzyaloshinskii interaction, this magnetic field leads to a coupling between the helix chirality and the magnetochirality and breaks mirror symmetry in the spin-wave spectrum: the modification of magnon dispersion relation is linear with respect to the torsion and quadratic with respect to the curvature. All analytical predictions on magnetization statics and dynamics are well confirmed by direct spin-lattice simulations.

  15. Torsion and geometrostasis in covariant superstrings

    SciTech Connect

    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.

  16. Torsion and buckling of open sections

    NASA Technical Reports Server (NTRS)

    Wagner, Herbert

    1936-01-01

    In this paper is a discussion of the general principles for open sections of any shape. In what follows the torsion will be computed and on the basis of the results it will be possible to obtain a proper design of section in each case. The torsion of buckling members for the case where they are centrally loaded, leads to a problem in pure stability and is similar to that of stressed beams.

  17. Magnetic resonance imaging of experimental testicular torsion.

    PubMed

    Kaipia, A; Ryymin, P; Mäkelä, E; Aaltonen, M; Kähärä, V; Kangasniemi, M

    2005-12-01

    We investigated the feasibility of contrast enhanced (CE)-dynamic magnetic resonance imaging (MRI) for the detection of testicular torsion induced hypoperfusion in an experimental rat model. Adult Sprague-Dawley rats were subjected to unilateral testicular torsion of 360 or 720 degrees. After 1 h, the tail veins of the anaesthetized rats were cannulated and T2 -, diffusion-weighted and T1-weighted CE-dynamic MRI were subsequently performed by a 1.5 T MRI scanner. On apparent diffusion coefficient (ADC) images, the region of interest values of the ischaemic and control testes was compared. From CE-dynamic MR images, the maximal slopes of contrast enhancement were calculated and compared. In testicular torsion of 360 degrees, the maximal slope of contrast enhancement was 0.072%/s vs. 0.47%/s in the contralateral control testis (p < 0.001). A torsion of 720 degrees diminished the slope of contrast enhancement to 0.046%/s vs. 0.37%/s in the contralateral testis (p < 0.001). Diminished blood flow during torsion also followed in decreased ADC values in both 360 degrees (12.4% decrease; p < 0.05) and 720 degrees (10.8% decrease; p < 0.001) of torsion. Torsion of the testis causes ipsilateral hypoperfusion and decreased gadolinium uptake in a rat model that can be easily detected and quantified by CE-dynamic MRI. In diffusion-weighted MRI images, acute hypoperfusion results in a slight decrease of ADC values. Our results suggest that CE-dynamic MRI in combination with diffusion-weighted MRI can be used to detect compromised blood flow due to acute testicular torsion.

  18. Attentional Modulation of Eye Torsion Responses

    NASA Technical Reports Server (NTRS)

    Stevenson, Scott B.; Mahadevan, Madhumitha S.; Mulligan, Jeffrey B.

    2016-01-01

    Eye movements generally have both reflexive and voluntary aspects, but torsional eye movements are usually thought of as a reflexive response to image rotation around the line of sight (torsional OKN) or to head roll (torsional VOR). In this study we asked whether torsional responses could be modulated by attention in a case where two stimuli rotated independently, and whether attention would influence the latency of responses. The display consisted of rear-projected radial "pinwheel" gratings, with an inner annulus segment extending from the center to 22 degrees eccentricity, and an outer annulus segment extending from 22 degrees out to 45 degrees eccentricity. The two segments rotated around the center in independent random walks, stepping randomly 4 degrees clockwise or counterclockwise at 60 Hz. Subjects were asked to attend to one or the other while keeping fixation steady at the center of the display. To encourage attention on one or the other segment of the display, subjects were asked to move a joystick in synchrony with the back and forth rotations of one part of the image while ignoring the other. Eye torsion was recorded with the scleral search coil technique, sampled at 500 Hz. All four subjects showed roughly 50% stronger torsion responses to the attended compared to unattended segments. Latency varied from 100 to 150 msec across subjects and was unchanged by attention. These findings suggest that attention can influence eye movement responses that are not typically under voluntary control.

  19. Torsional Optomechanics of a Levitated Nonspherical Nanoparticle

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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 1 order of magnitude higher than its center-of-mass motion frequency, which is promising for ground state cooling. 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 torsion balance with a torque detection sensitivity on the order of 10-29 N m /√{Hz } under realistic conditions.

  20. Cross-shaped torsional spring

    DOEpatents

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

    1999-06-08

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

  1. Cross-shaped torsional spring

    DOEpatents

    Williamson, Matthew M.; Pratt, Gill A.

    1999-06-08

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

  2. Torsional oscillations in dynamo simulations

    NASA Astrophysics Data System (ADS)

    Wicht, Johannes; Christensen, Ulrich R.

    2010-06-01

    Cylinders aligned with the planetary rotation axis have a special significance in the dynamics of planetary dynamo regions. The azimuthal Lorentz forces on these geostrophic cylinders is expected to cancel to a large degree, establishing the so-called Taylor state. Deviations from this state take the form of torsional oscillations (TOs) that are supposed to represent important fast flow variations. These oscillations have reportedly been identified in the secular variation signal from the top of Earth's core. We have performed several dynamo simulations at different parameters to check whether Taylor state and TOs can also be identified in a numerical model. Taylor states are approached when viscous effects are small at Ekman numbers of E = 3 × 10-5 or below and Reynolds stresses are kept low by choosing moderate Rayleigh numbers. One-dimensional magnetic Alfvén waves that travel towards the boundaries then become prominent in the motion of the geostrophic cylinders. These waves obey the TO theory but are also damped and modified by other effects. For example, fast variations of likely convective origin remain important in all our simulations. Reynolds stresses may play a more sizable role for the dynamics in Earth's dynamo region than commonly assumed. They may also contribute to the motions of geostrophic cylinders and severely reduce the significance of TOs for the fast core dynamics. The amplitude of TOs amounts to not more than a few percent of the total flow amplitude in the simulations, which renders these motions insignificant for the long-term dynamo process.

  3. Endodontic instruments after torsional failure: nanoindentation test.

    PubMed

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

    2014-01-01

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

  4. Inferior alveolar nerve paresthesia relieved by microscopic endodontic treatment.

    PubMed

    Yatsuhashi, Takaaki; Nakagawa, Kan-Ichi; Matsumoto, Miho; Kasahara, Masataka; Igarashi, Tomoko; Ichinohe, Tatsuya; Kaneko, Yuzuru

    2003-11-01

    We experienced two cases of inferior alveolar nerve paresthesia caused by root canal medicaments, which were successfully relieved by microscopic endodontic treatment. In the first case, the paresthesia might have been attributable to infiltration of calcium hydroxide into the mandibular canal through the root canals of the mandibular left second molar tooth. In the second case, the paresthesia might have been attributable to infiltration of paraformaldehyde through the root canals of the mandibular right second molar tooth. The paresthesia was relieved in both cases by repetitive microscopic endodontic irrigation using physiological saline solution in combination with oral vitamin B12 and adenosine triphosphate.

  5. Mechanical behavior of twinned SiC nanowires under combined tension-torsion and compression-torsion strain

    SciTech Connect

    Li, Zhijie; Wang, Shengjie; Wang, Zhiguo; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

    2010-07-01

    The mechanical behavior of twinned silicon carbide (SiC) nanowires under combined tension-torsion and compression-torsion is investigated using molecular dynamics simulations with an empirical potential. The simulation results show that both the tensile failure stress and buckling stress decrease under combined tension-torsional and combined compression-torsional strain, and they decrease with increasing torsional rate under combined loading. The torsion rate has no effect on the elastic properties of the twinned SiC nanowires. The collapse of the twinned nanowires takes place in a twin stacking fault of the nanowires.

  6. Active structures to reduce torsional vibrations

    NASA Astrophysics Data System (ADS)

    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.

  7. DNA.

    ERIC Educational Resources Information Center

    Felsenfeld, Gary

    1985-01-01

    Structural form, bonding scheme, and chromatin structure of and gene-modification experiments with deoxyribonucleic acid (DNA) are described. Indicates that DNA's double helix is variable and also flexible as it interacts with regulatory and other molecules to transfer hereditary messages. (DH)

  8. Torsional wave propagation in solar tornadoes

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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.

  9. Acute Scrotum Caused by Hernia Sac Torsion.

    PubMed

    Fukui, Shinji; Aoki, Katsuya; Shimada, Keiji; Samma, Shoji

    2016-03-01

    A 9-year-old boy was referred to us with an acute pain attack of the left scrotal contents. Ultrasonography showed a normal blood supply to the left testis, suggesting an incarcerated left inguinal hernia. Surgical exploration did not demonstrate an incarcerated left inguinal hernia. After exploration of the left testis, a dark red pedunculated cystic mass, separate from the left testis, was found to be twisted. Immunohistochemical studies of the excised cyst demonstrated torsion of the hernia sac of the peritoneum. In conclusion, we encountered a case of acute scrotum which was probably caused by torsion of the hernia sac.

  10. Acute torsion of a wandering spleen.

    PubMed

    Lam, Y; Yuen, Kenny K Y; Chong, L C

    2012-04-01

    The 'wandering spleen' is a rare condition due to extreme laxity or absence of ligaments that fix the organ in its normal anatomical position within the left upper quadrant. Without early surgical intervention, wandering spleen can lead to torsion and subsequent splenic infarction or rupture. Clinical suspicion plus urgent investigation and intervention are important, so as to salvage the spleen and prevent complications. We present a case of torsion of a wandering spleen in a 21-year-old young woman, who presented with a painful pelvic mass. We also reviewed the literature on this entity.

  11. Wandering spleen with torsion and complete infarction.

    PubMed

    Chu, Jianping; Li, Ziping; Luo, Boning; Yang, Jianyong

    2011-10-01

    Wandering spleen is rare and is associated with a high incidence of splenic torsion and infarction. Presenting symptoms range from an asymptomatic, incidentally palpated abdominal mass to an acutely ill patient. Because wandering spleen is uncommon in the pediatric population, a heightened awareness of the condition is required for accurate diagnosis and appropriate management. We present a case of a 4-year-old girl who presented with acute abdomen and was surgically confirmed to have a wandering spleen with torsion and complete infarction.

  12. Improved Coating System for High Strength Torsion Bars

    DTIC Science & Technology

    1981-04-23

    SwW IMPROVED COATING SYSTEM FOR HIGH S- TYPE Of REPORT & PEROo CovERED STRENGTH TORSION BAR Final Report Plastisol Coating System Provides a Cost...8217 mumber) Torsion Bar Plastisol Coating Inorganic Coating Protective Coating Polyvinyl Chloride Coating Polyurethane Coating Corrosion Protection Tape...Bars E. Endurance Test Results for One-third Length Torsion E-1 Bar F. Specification for Application of Plastisol to High F-1 Strength Torsion Bar

  13. Tussive syncope in a pug with lung-lobe torsion.

    PubMed

    Davies, John A; Snead, Elisabeth C R; Pharr, John W

    2011-06-01

    The most common presenting clinical signs of lung-lobe torsion include dyspnea, tachypnea, lethargy, and anorexia. Tussive syncope secondary to lung-lobe torsion has not been documented. This article describes the presentation, diagnosis, management, and outcome of a pug with tussive syncope secondary to lung-lobe torsion.

  14. Cryptorchid testis with torsion: Inguinoscrotal whirlpool sign

    PubMed Central

    Indiran, Venkatraman

    2016-01-01

    Non contrast helical computed tomography (CT) study of the abdomen is frequently performed in evaluation of suspected ureteric colic. We present CT images of a young adult male patient who had torsion of an undescended, non-neoplastic testis and describe the “Inguinoscrotal whirlpool sign on CT”. PMID:27555688

  15. Clinical Characteristics of Torsion of the Omentum

    PubMed Central

    Montiel-Jarquin, Alvaro; Lopez-Colombo, Aurelio; Nava, Arnulfo; Juarez-Santiesteban, Rayo; Leyva-Trejo, Hugo; Zamora-Ustaran, Alfonso; García-Carrasco, Mario; Munoz-Guarneros, Margarita

    2009-01-01

    Background The aim of this paper is to describe clinical aspects of the torsion of the omentum. Methods In this observational, retrospective study, the study group consisted of patients surgically managed for torsion of the omentum, between 1998 and 2008, in a second level medical facility in Mexico. Variables in the study included age, sex, signs and symptoms, body mass index (BMI), treatment and evolution time. Descriptive statistical analysis was employed. Results Eleven patients were confirmed torsion of omentum, 7 (63.63%) women and 4 (36.36%) men, median age 33 (20 to 58) years, BMI > 25.0 in 9 (81.81%), average evolution 6.54, SD 3.47 days. All presented with abdominal pain, 6 (54.54%) with abdominal distension, 4 (36.36%) with ambulatory difficulty, 3 (27.27%) with malaise, and 5 (45.45%) with previous surgery. In all cases diagnosis was made by means of laparotomy, treatment was the resection of the affected segment, and there were no further complications. Conclusions Torsion of the omentum resembles acute appendicitis; abdominal pain and abdominal distension are the most common symptoms. It is often discovered during surgery and it is treated surgically by removal of the affected segment of the omentum. PMID:27942278

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

    PubMed Central

    Fakhry, Mohamed A; Shazly, Malak I El

    2011-01-01

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

  17. Torsion of a Large Appendix Testis Misdiagnosed as Pyocele

    PubMed Central

    Meher, Susanta; Rath, Satyajit; Sharma, Rakesh; Sasmal, Prakash Kumar; Mishra, Tushar Subhadarshan

    2015-01-01

    Torsion of the appendix testis is not an uncommon cause of acute hemiscrotum. It is frequently misdiagnosed as acute epididymitis, orchitis, or torsion of testis. Though conservative management is the treatment of choice for this condition, prompt surgical intervention is warranted when testicular torsion is suspected. We report a case of torsion of a large appendix testis misdiagnosed as pyocele. Emergency exploration of it revealed a large appendix testis with torsion and early features of gangrene. After excision of the appendix testis, the wound was closed with an open drain. The patient had an uneventful and smooth postoperative recovery. PMID:25861514

  18. Torsion of an intra-abdominal testis.

    PubMed

    Lewis; Roller; Parra; Cotlar

    2000-09-01

    To present a case of torsion of a nonneoplastic intra-abdominal testis with an unusual clinical presentation.A 26-year-old active duty Navy Petty Officer presented to the emergency department on 3 occasions over a 5-day period with lower abdominal pain. Physical examination demonstrated acute tenderness in the left lower quadrant with sugestion of a normal spermatic cord and atrophic testis in the left scrotum. Computed tomography scan demonstrated an intra-abdominal lesion near the internal inguinal ring. The patient underwent surgical exploration through an inguinal incision. Torsion of a nonviable intra-abdominal testis was present. The scrotum contained only the vas deferens and cremasteric muscle. An orchiectomy was performed with removal of the vas deferens and other cord structures.The unusual clinical finding of acute torsion of an intra-abdominal testis, associated with an apparent atrophic scrotal testis, presented a confusing clinical picture. Computed tomography scan did not clarify the issue sufficiently to establish a definite preoperative diagnosis. Clinical suspicion prompted early surgical intervention. Review of the current literature produced 60 reported cases of torsion of an intra-abdominal testis. Two thirds of these involved testicular neoplasm, usually seminoma. Although the clinical presentation varied, most patients had recent onset of lower abdominal pain associated with tenderness and, in half the cases, a mass. Patients almost always presented with an absent scrotal testis on the involved side, and not infrequently reported previous surgery thought to be an orchiectomy.Diagnosis of an intra-abdominal testicular torsion is rare, particularly when no neoplasm is present. A high index of suspicion must be maintained whenever there is abdominal pain and undescended testis. The surgical history and imaging studies may not clarify a confusing clinical picture.

  19. Ultrasonography of Extravaginal Testicular Torsion in Neonates

    PubMed Central

    Bombiński, Przemysław; Warchoł, Stanisław; Brzewski, Michał; Majkowska, Zofia; Dudek-Warchoł, Teresa; Żerańska, Maria; Panek, Małgorzata; Drop, Magdalena

    2016-01-01

    Summary Background Extravaginal testicular torsion (ETT), also called prenatal or perinatal, occurs prenatally and is present at birth or appears within the first month of life. It has different etiology than intravaginal torsion, which appears later in life. Testicular torsion must be taken into consideration in differential diagnosis of acute scrotum and should be confirmed or ruled out at first diagnostic step. Ultrasonography is a basic imaging modality, however diagnostic pitfalls are still possible. There is still wide discussion concerning management of ETT, which varies from immediate orchiectomy to conservative treatment resulting in testicle atrophy. Material/Methods In this article we present ultrasonographic spectrum of ETT in neonates, which were diagnosed and treated in our hospital during the last 8 years (2008–2015), in correlation with clinical and intraoperative findings. Results Thirteen neonates with ETT were enrolled in the study – 11 patients with a single testicle affected and 2 patients with bilateral testicular torsion. Most common signs on clinical examination were: hardened and enlarged testicle and discoloration of the scrotum. Most common ultrasonographic signs were: abnormal size or echostructure of the affected testicle and absence of the blood flow in Doppler ultrasonography. In 3 patients ultrasound elastography was performed, which appeared very useful in testicle structure assessment. Conclusions Testicular torsion may concern boys even in the perinatal period. Ultrasonographic picture of acute scrotum in young boys may be confused. Coexistence of the abnormal size or echostructure of the torsed testicle with absence of the blood flow in Doppler ultrasonography appear as very specific but late ultrasonographic sings. Ultrasound elastography may be a very useful tool for visualisation of a very common clinical sign – hardening of the necrotic testicle. PMID:27757176

  20. Design and analysis of a torsion braid pendulum displacement transducer

    NASA Technical Reports Server (NTRS)

    Rind, E.; Bryant, E. L.

    1981-01-01

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

  1. DNA

    ERIC Educational Resources Information Center

    Stent, Gunther S.

    1970-01-01

    This history for molecular genetics and its explanation of DNA begins with an analysis of the Golden Jubilee essay papers, 1955. The paper ends stating that the higher nervous system is the one major frontier of biological inquiry which still offers some romance of research. (Author/VW)

  2. Laser-Based Measurement Of Torsional Vibration

    NASA Astrophysics Data System (ADS)

    Eastwood, P. G.; Halliwell, N. A.

    1986-07-01

    Investigations of the torsional vibration characteristics of shaft systems which transmit pulsating torques are an important part of a machinery designer's responsibility. Satisfactory operation of such systems depends to a large extent on successful treatment of this vibration problem, since incorrectly or insufficiently controlled torsional oscillations can lead to fatigue failure, rapid bearing wear, gear hammer etc. The problem is particularly severe in engine crankshaft design where numerous failures have been traced to abnormal vibration at "critical" speeds. Traditionally, the monitoring of torsional oscillation has been performed using strain gauges, slip rings and a variety of mechanical and electrical "torsiographs". More recently systems employing slotted discs or toothed wheels together with proximity transducers have been preferred, but a disadvantage arises from all these methods in that they require contact with the rotating component which necessitates "downtime" for transducer attachment. Moreover, physical access to the rotating surface is often restricted thus making the use of such methods impractical. The "cross-beam" laser velocimeter provides a means of measuring torsional vibration by a non-contact method, thus effectively overcoming the disadvantages of previous measurement systems. This well established laser-based instrument provides a time-resolved voltage analogue of shaft tangential surface velocity and laboratory and field tests have shown it to be both accurate and reliable. The versatility of this instrument, however, is restricted by the need for accurate positioning, since the velocimeter must be arranged so that the rotating surface always traverses the beam intersection region, which is typically only a fraction of a millimetre in length. As a consequence use is restricted to components of circular cross section. This paper compares and contrasts the "cross-beam" system with a new laser instrument, the laser torsional vibrometer

  3. Strain softening in stretched DNA

    PubMed Central

    Luan, Binquan; Aksimentiev, Aleksei

    2010-01-01

    The microscopic mechanics of DNA stretching was characterized using extensive molecular dynamics simulations. By employing an anisotropic pressure control method, realistic force-extension dependences of effectively infinite DNA molecules were obtained. A coexistence of B- and S-DNA domains was observed during the overstretching transition. The simulations revealed that strain softening may occur in the process of stretching torsionally constrained DNA. The latter observation was qualitatively reconciled with available experimental data using a random-field Ising model. PMID:18851334

  4. Axial and torsional fatigue behavior of Waspaloy

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  5. Chronic splenic torsion in two dogs.

    PubMed

    Reinhart, Jennifer M; Sherwood, J Matthew; KuKanich, Katherine S; Klocke, Emily; Biller, David S

    2015-01-01

    A 5 yr old spayed female poodle (case 1) was presented with a 4 mo history of lethargy, inappetence, and nonregenerative anemia. A 5 yr old castrated male French bulldog (case 2) was presented with a 2 wk history of mild abdominal pain, dyschezia, and intermittent anorexia. Both dogs were diagnosed with chronic splenic torsion based on changes in splenic position, echogenicity, and/or echotexture identified on B-mode abdominal ultrasonography, as well as either decreased or absent splenic blood flow on color-flow Doppler ultrasonography. Both dogs underwent splenectomy and had full resolution of clinical signs. Presentation of chronic splenic torsion is variable, and clinical signs can be nonspecific. Abdominal ultrasound with Doppler evaluation is an important diagnostic step that can lead to appropriate surgical intervention and good long-term prognosis.

  6. Torsional Tribological Behavior and Torsional Friction Model of Polytetrafluoroethylene against 1045 Steel.

    PubMed

    Wang, Shibo; Niu, Chengchao

    2016-01-01

    In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T-θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model.

  7. Torsional Tribological Behavior and Torsional Friction Model of Polytetrafluoroethylene against 1045 Steel

    PubMed Central

    Wang, Shibo; Niu, Chengchao

    2016-01-01

    In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T–θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model. PMID:26799324

  8. Myocardial Rotation and Torsion in Child Growth

    PubMed Central

    Kim, Chang Sin; Park, Sora

    2016-01-01

    Background The speckle tracking echocardiography can benefit to assess the regional myocardial deformations. Although, previous reports suggested no significant change in left ventricular (LV) torsion with aging, there are certain differences in LV rotation at the base and apex. The purpose of this study was to evaluate the change and relationship of LV rotation for torsion with aging in children. Methods Forty healthy children were recruited and divided into two groups of twenty based on whether the children were preschool-age (2–6 years of age) or school-age (7–12 years of age). After obtaining conventional echocardiographic data, apical and basal short axis rotation were assessed with speckle tracking echocardiography. LV rotation in the basal and apical short axis planes was determined using six myocardial segments along the central axis. Results Apical and basal LV rotation did not show the statistical difference with increased age between preschool- and school-age children. Apical radial strain showed significant higher values in preschool-age children, especially at the anterior (52.8 ± 17.4% vs. 34.7 ± 23.2%, p < 0.02), lateral (55.8 ± 20.4% vs. 36.1 ± 22.7%, p < 0.02), and posterior segments (57.1 ± 17.6% vs. 38.5 ± 21.7%, p < 0.01). The torsion values did not demonstrate the statistical difference between two groups. Conclusion This study revealed the tendency of higher rotation values in preschool-age children than in school-age children. The lesser values of rotation and torsion with increased age during childhood warrant further investigation. PMID:27721953

  9. Fluid driven torsional dipole seismic source

    DOEpatents

    Hardee, Harry C.

    1991-01-01

    A compressible fluid powered oscillating downhole seismic source device capable of periodically generating uncontaminated horizontally-propagated, shear waves is provided. A compressible fluid generated oscillation is created within the device which imparts an oscillation to a housing when the device is installed in a housing such as the cylinder off an existing downhole tool, thereby a torsional seismic source is established. Horizontal waves are transferred to the surrounding bore hole medium through downhole clamping.

  10. TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS

    SciTech Connect

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

    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.

  11. UBIQUITOUS TORSIONAL MOTIONS IN TYPE II SPICULES

    SciTech Connect

    De Pontieu, B.; Hansteen, V. H.; Carlsson, M.; Rouppe van der Voort, L. H. M.; Rutten, R. J.; Watanabe, H.

    2012-06-10

    Spicules are long, thin, highly dynamic features that jut out ubiquitously from the solar limb. They dominate the interface between the chromosphere and corona and may provide significant mass and energy to the corona. We use high-quality observations with the Swedish 1 m Solar Telescope to establish that so-called type II spicules are characterized by the simultaneous action of three different types of motion: (1) field-aligned flows of order 50-100 km s{sup -1}, (2) swaying motions of order 15-20 km s{sup -1}, and (3) torsional motions of order 25-30 km s{sup -1}. The first two modes have been studied in detail before, but not the torsional motions. Our analysis of many near-limb and off-limb spectra and narrowband images using multiple spectral lines yields strong evidence that most, if not all, type II spicules undergo large torsional modulation and that these motions, like spicule swaying, represent Alfvenic waves propagating outward at several hundred km s{sup -1}. The combined action of the different motions explains the similar morphology of spicule bushes in the outer red and blue wings of chromospheric lines, and needs to be taken into account when interpreting Doppler motions to derive estimates for field-aligned flows in spicules and determining the Alfvenic wave energy in the solar atmosphere. Our results also suggest that large torsional motion is an ingredient in the production of type II spicules and that spicules play an important role in the transport of helicity through the solar atmosphere.

  12. DNA supercoiling and its role in DNA decatenation and unknotting

    PubMed Central

    Witz, Guillaume; Stasiak, Andrzej

    2010-01-01

    Chromosomal and plasmid DNA molecules in bacterial cells are maintained under torsional tension and are therefore supercoiled. With the exception of extreme thermophiles, supercoiling has a negative sign, which means that the torsional tension diminishes the DNA helicity and facilitates strand separation. In consequence, negative supercoiling aids such processes as DNA replication or transcription that require global- or local-strand separation. In extreme thermophiles, DNA is positively supercoiled which protects it from thermal denaturation. While the role of DNA supercoiling connected to the control of DNA stability, is thoroughly researched and subject of many reviews, a less known role of DNA supercoiling emerges and consists of aiding DNA topoisomerases in DNA decatenation and unknotting. Although DNA catenanes are natural intermediates in the process of DNA replication of circular DNA molecules, it is necessary that they become very efficiently decatenated, as otherwise the segregation of freshly replicated DNA molecules would be blocked. DNA knots arise as by-products of topoisomerase-mediated intramolecular passages that are needed to facilitate general DNA metabolism, including DNA replication, transcription or recombination. The formed knots are, however, very harmful for cells if not removed efficiently. Here, we overview the role of DNA supercoiling in DNA unknotting and decatenation. PMID:20026582

  13. Big bounce from spin and torsion

    NASA Astrophysics Data System (ADS)

    Popławski, Nikodem J.

    2012-04-01

    The Einstein-Cartan-Sciama-Kibble theory of gravity naturally extends general relativity to account for the intrinsic spin of matter. Spacetime torsion, generated by spin of Dirac fields, induces gravitational repulsion in fermionic matter at extremely high densities and prevents the formation of singularities. Accordingly, the big bang is replaced by a bounce that occurred when the energy density {ɛ ∝ gT^4} was on the order of {n^2/m_Pl^2} (in natural units), where {n ∝ gT^3} is the fermion number density and g is the number of thermal degrees of freedom. If the early Universe contained only the known standard-model particles ( g ≈ 100), then the energy density at the big bounce was about 15 times larger than the Planck energy. The minimum scale factor of the Universe (at the bounce) was about 1032 times smaller than its present value, giving ≈ 50 μm. If more fermions existed in the early Universe, then the spin-torsion coupling causes a bounce at a lower energy and larger scale factor. Recent observations of high-energy photons from gamma-ray bursts indicate that spacetime may behave classically even at scales below the Planck length, supporting the classical spin-torsion mechanism of the big bounce. Such a classical bounce prevents the matter in the contracting Universe from reaching the conditions at which a quantum bounce could possibly occur.

  14. Evaluation of the torsional VOR in weightlessness.

    PubMed

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

    1993-01-01

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

  15. Neonatal testicular torsion: a systematic literature review.

    PubMed

    Nandi, Biplab; Murphy, Feilim Liam

    2011-10-01

    Neonatal testicular torsion (NTT) is rare and reported salvage rates vary widely both in their cited frequency and plausibility. The timing and necessity of surgery is controversial with different centers arguing for the conservative management of all cases while others argue for prompt exploration for all. Confusion also reigns over the need to fix the contralateral testis. In order to clarify the issue the authors reviewed the literature and found 18 case series of NTT, containing 268 operated cases suitable for analysis. This paper reviews the literature on NTT specifically regarding salvage rates and timing/necessity of surgery. Its primary aim is to produce an overall salvage rate in the operated group. Overall salvage rate was 8.96%, 24 testes. When operation is specified as an emergency, salvage may be as high as 21.7%. While salvage of a testis torted at birth is rare, it is reported. Early asynchronous torsion is also rare but reported. Worryingly, bilateral torsion can present with unilateral signs.Given these findings, we would suggest early surgery with fixation of the contralateral side.

  16. Perinatal testicular torsion and medicolegal considerations.

    PubMed

    Massoni, F; Troili, G M; Pelosi, M; Ricci, S

    2014-06-01

    Perinatal testicular torsion (PTT) is a very complex condition because of rarity of presentation and diagnostic and therapeutic difficulties. In presence of perinatal testicular torsion, the involvement of contralateral testis can be present also in absence of other indications which suggest the bilateral involvement; therefore, occurrences supported by literature do not exclude the use of surgery to avoid the risk of omitted or delayed diagnosis. The data on possible recovery of these testicles are not satisfactory, and treatment consists of an observational approach ("wait-and-see") or an interventional approach. The hypothesis of randomized clinical trials seems impracticable because of rarity of disease. The authors present a case of PTT, analyzing injuries due to clinical and surgical management of these patients, according to medicolegal profile. The delayed diagnosis and the choice of an incorrect therapeutic approach can compromise the position of healthcare professionals, defective in terms of skill, prudence and diligence. Endocrine insufficiency is an unfortunate event. The analysis of literature seems to support, because of high risk, a surgical approach aimed not only at resolution of unilateral pathology or prevention of a relapse, but also at prevention of contralateral testicular torsion.

  17. Polyorchidism with presumed contralateral intrauterine testicular torsion

    PubMed Central

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

    2014-01-01

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

  18. Best Way to Take Your Over-the-Counter Pain Reliever? Seriously.

    MedlinePlus

    ... best way to take your over-the-counter pain reliever? Seriously. Share Tweet Linkedin Pin it More sharing ... Print (PDF version - 6MB) Over-the-counter (OTC) pain relievers/fever reducers (the kind you can buy without ...

  19. Interplay between DNA supercoiling and transcription elongation.

    PubMed

    Ma, Jie; Wang, Michelle

    2014-01-01

    Transcription-coupled DNA supercoiling has been shown to be an important regulator of transcription that is broadly present in the cell. Here we review experimental work which shows that RNA polymerase is a powerful torsional motor that can alter DNA topology and structure, and DNA supercoiling in turn directly affects transcription elongation.

  20. Robot Drills Holes To Relieve Excess Tire Pressures

    NASA Technical Reports Server (NTRS)

    Carrott, David T.

    1996-01-01

    Small, relatively inexpensive, remotely controlled robot called "tire assault vehicle" (TAV) developed to relieve excess tire pressures to protect ground crew, aircraft equipment, and nearby vehicles engaged in landing tests of CV-990 Landing System Research Aircraft. Reduces costs and saves time in training, maintenance, and setup related to "yellow" and "red" tire conditions. Adapted to any heavy-aircraft environment in which ground-crew safety at risk because of potential for tire explosions. Also ideal as scout vehicle for performing inspections in hazardous locations.

  1. Torsion-rotation intensities in methanol

    NASA Astrophysics Data System (ADS)

    Pearson, John

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

  2. Biothermal sensing of a torsional artificial muscle

    NASA Astrophysics Data System (ADS)

    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

  3. Design of a nonlinear torsional vibration absorber

    NASA Astrophysics Data System (ADS)

    Tahir, Ammaar Bin

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

  4. 31 CFR 585.521 - Donations of food to relieve human suffering authorized.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Donations of food to relieve human... Donations of food to relieve human suffering authorized. (a) Specific licenses may be issued on a case-by-case basis to permit exportation to the FRY (S&M) of donated food intended to relieve human...

  5. Missed Spermatic Cord Torsion in an Old Man

    PubMed Central

    Seo, Yu Mi; Myung, Na-Hye

    2013-01-01

    The fate of testicular salvage in spermatic cord torsion depends on the duration of ischemia and the degree of torsion. Even though spermatic cord torsion (SCT) can occur at any age, it is rarely reported in older patients. If the physician does not pay close attention to this unusual situation, the lack of suspicion for SCT may result in a missed or delayed diagnosis. We report a very uncommon case of missed SCT occurring in a 63-year-old man. PMID:24175049

  6. Torsion in wandering spleen: CT demonstration of whirl sign.

    PubMed

    Priyadarshi, Rajeev N; Anand, Utpal; Kumar, Bindey; Prakash, Vijay

    2013-08-01

    Wandering spleen is a rare occurrence. Torsion of the splenic pedicle is the major life-threatening complication of this entity. Preoperative diagnosis is based on radiological investigation. We report two consecutive cases, one adult and one child, in whom torsion in a wandering spleen was diagnosed based on a typical whirled appearance of the splenic vessels on computed tomography. We present a review of computed tomographic appearance of splenic torsion, and emphasize the "whirled appearance" as a specific sign for splenic torsion in wandering spleen.

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:26425241

  9. The Torsional Spectrum of Doubly Deuterated Methanol CHD_2OH

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Although the torsional spectrum of several isotopic species of methanol with a symmetrical CH_3 or CD_3 was analyzed some time ago, it is recently, and only for the monodeuterated species CH_2DOH, that such an analysis was extended to the case of an asymmetrical methyl group. In this talk, based on a Fourier transform high-resolution spectrum recorded in the 20 to 670 wn region, the first analysis of the torsional spectrum of doubly deuterated methanol CHD_2OH will be presented. The Q branch of many torsional subbands could be observed and their assignment was initiated using a theoretical torsion-rotation spectrum computed with an approach accounting for the torsion-rotation Coriolis coupling and for the dependence of the generalized inertia tensor on the angle of internal rotation. 46 torsional subbands were thus assigned. For 28 of them, their rotational structure could be assigned and fitted using an effective Hamiltonian expressed as a J(J+1) expansion; and for 2 of them microwave transitions within the lower torsional level could also be included in the analysis. In several cases these analysis revealed that the torsional levels are strongly perturbed. In the talk, the torsional parameters retrieved in the analysis of the torsional subband centers will be discussed. The results of the analysis of the rotational structure of the torsional subbands will be presented and we will also try to understand the nature of the perturbations. At last, preliminary results about the analysis of the microwave spectrum will be presented. El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. 135 (2011) 194309 Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spectrosc. 256 (2009) 204 Quade, Liu, Mukhopadhyay, and Su, J. Mol. Spectrosc. 192 (1998) 378 Pearson, Yu, and Drouin, J. Mol. Spectrosc. 280 (2012) 119

  10. Primary torsion of the greater omentum.

    PubMed

    Gul, Y A; Jabbar, M F; Moissinac, K

    2001-01-01

    Primary or idiopathic greater omental torsion remains a rare cause of acute surgical abdomen in adults and children. The aetiology is as yet unknown and the treatment of choice, once diagnosis is established, is resection of the torted omentum. We report our experience with three such cases encountered over the last five years, two of which were diagnosed and subsequently managed laparoscopically. The performance of diagnostic laparoscopy for acute abdominal pain of an undetermined origin may lead to an increased detection of this condition and subsequent therapeutic intervention.

  11. Two design strategies for enhancement of multilayer–DNA-origami folding: underwinding for specific intercalator rescue and staple-break positioning

    PubMed Central

    Ke, Yonggang; Bellot, Gaëtan; Voigt, Niels V.; Fradkov, Elena; Shih, William M.

    2012-01-01

    Single-layer DNA origami is an efficient method for programmable self-assembly of nanostructures approximating almost any desired two-dimensional shape from ~5 MDa of DNA building material. In this method, a 7 kilobase single “scaffold” strand is assembled with hundreds of oligodeoxyribonucleotide “staple” strands to form a parallel array of double helices. Multiple layers of such DNA sheets also can be designed to assemble into a stack, enabling construction of solid three-dimensional shapes with considerably greater mechanical rigidity than two-dimensional shapes; however, the folding yield often is much lower and the required folding times are much longer. Here we introduce two strategies for designing multi-layer DNA origami that demonstrate potential for boosting assembly yield: (1) individual base pairs can be inserted between crossovers, allowing for greater bowing of helices at positions away from crossovers and therefore reduced electrostatic repulsion. At the same time, this underwinding of double helices increases a destabilizing torsional strain energy but then also increases affinity for intercalators, and binding of such intercalators can relieve this stress. We also have exploited this enhanced affinity for intercalators to PEGylate the surface of the nanostructures in a noncovalent fashion using PEG-tris-acridine. (2) Positioning of staple-strand breaks in the DNA origami such that each staple strand includes a 14 nucleotide (nt) continuous segment that binds to a complementary 14 nt continuous segment of the scaffold can greatly improve folding yields. PMID:24653832

  12. Pain-relieving effect of local steroid injection in uvulopalatopharyngoplasty.

    PubMed

    Hirunwiwatkul, P

    2001-06-01

    An analytical prospective study was performed to determine the post-operative pain-relieving effect of local steroid suspension injection in uvulopalatopharyngoplasty. From February 2000 to October 2000, 48 adult patients from 20 to 67 years of age, were scheduled to receive uvulopalatopharyngoplasty. Triamcinolone acetonide (Kenacort A) was injected onto the raw surface of the left-sided tonsillar fossa and left-sided soft palate after tonsillectomy and uvulopalatopharyngoplasty. Other preoperative and post-operative medications including antibiotics, anesthesia and surgical techniques were standardized. Visual analog scales were used to assess the level of pain sensation on the left and right side of the throat daily from day 0 (Operative day) to post-operative day 10. A paired t-test showed significant differences in post-operative pain level between the study side (left) and the control side (right) at day 2, day 4, and in the overall analysis (p < 0.05).

  13. Nonmedical prescription pain reliever and alcohol consumption among cannabis users

    PubMed Central

    Novak, Scott P.; Peiper, Nicholas C.; Zarkin, Gary A.

    2016-01-01

    Background This study examined poly-drug use involving the use of cannabis with nonmedical prescription pain reliever use (NMPR) and alcohol use. Methods Computer-assisted survey data from the National Survey on Drug Use and Health were examined. The NSDUH is an annual, cross-sectional survey of non-institutionalized citizens in the United States (ages 12+). Replicate analyses were conducted using the 2013 and 2003 survey waves. Results Higher levels of cannabis use were consistently associated with more frequent consumption of prescription pain relievers, with findings replicating in both 2013 and 2003. While the prevalence of dual users declined from 2003 (2.5%) to 2013 (2.3%), the average number of days used among dual users increased by an average of 20 days over that period. These changes largely occurred among those aged 35 or older, males, whites, and non-illicit drug users. Past-year marijuana use increased by 16% (10.8–12.6%, p-value < .001) whereas NMPR decreased by 15% (4.9–4.2%, p-value < .001). The largest changes occurred after 2011. Persons using the most cannabis generally had higher levels of alcohol use relative to those using the least amount of cannabis. There was a significant increase in the prevalence of dual use between 2003 (10.2%) and 2013 (11.6%), while the prevalence of past-year alcohol use remained relatively stable. Conclusions Clinical efforts and public health interventions should consider the possible co-ingestion of cannabis with NMPR and alcohol, as concomitant use may portend negative health effects in the short and long-term. PMID:26748409

  14. Unusual DNA structures

    SciTech Connect

    Wells, R.D.; Harvey, S.C.

    1988-01-01

    The contents of this book are: Unusual DNS Structures and the Probes Used for Their Detection; The Specificity of Single Strand Specific Endonucleases; Chromatin STructure and DNA Structure at the hsp 26 Locus of Drosophilia; Cruciform Extrusion in Supercoiled DNA-Mechanisms and Contextual Influence; Torsional Stress, Unusual DNA Structures, and Eukaryotic Gene Expression; DNA Sequence and Structure: Bending to Biology. Cruciform Transitions Assayed Using a Psoralen Cross-linking Method: Applications to Measurements of DNA Torisonal Tension; NMR-Distance Geometry Studies of Helical Errors and Sequence Dependent Conformations of DNA in Solution; Hyperreactivity of the B-Z Junctions Probed by Two Aromatic Chemical Carcinogens; Inherently Curved DNA and Its Structural Elements; and DNA Flexibility Under Control: The Juma Algorithm and its Application to BZ Junctions.

  15. Torsional Strengthening of RC Beams Using GFRP Composites

    NASA Astrophysics Data System (ADS)

    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.

  16. Hydrostatic self-aligning axial/torsional mechanism

    DOEpatents

    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.

  17. Omental torsion in a guinea pig (Cavia porcellus)

    PubMed Central

    Shrubsole-Cockwill, Alana N.; Cockwill, Ken R.N.; Parker, Dennilyn L.

    2008-01-01

    An adult intact male guinea pig (Cavia porcellus) was presented with gastrointestinal stasis. Radiographic findings demonstrated a gas- and fluid-filled cecum. Treatment was initiated but the animal died shortly after presentation. Gross postmortem revealed omental torsion with vascular thrombosis and necrosis. This is the first report of omental torsion with vascular thrombosis in a domestic animal. PMID:19043488

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

    NASA Astrophysics Data System (ADS)

    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.

  19. [Cardiac herniation and torsion after transpericardial pneumonectomy].

    PubMed

    Schummer, W; Hottenrott, A; Nissel, C

    2016-07-05

    This article presents the case of a 43 year old woman with right-sided lung cancer. She underwent transpericardial pneumonectomy. After an uneventfull surgery, the patient was transferred to the intensive care unit for postoperative monitoring. She was hemodynamically stable and had already been extubated in the OR.On postoperative chest X‑ray a mediastinal shift to the operated side as well as a herniation of the heart into the right chest cavity was detected. While the patient remained hemodynamically stable a computed tomography of the chest was performed which confirmed the diagnosis of cardiac herniation and torsion. The lady underwent rethoracotomy the following day where the heart was repositioned and the pericardial defect was closed. She made an uneventfull recovery.Five years after the pneumonectomy she remains well and is without relapse of lung cancer.Mechanism for cardiac herniation and torsion, the clinical presentation and the typical radiologic signs are discussed. However, the clue to early diagnosis is a high index of clinical suspicion.It is highlighted that a hemodynamically unstable patient under these circumstances demands urgent rethoracotomy.

  20. Curvature and torsion in growing actin networks

    PubMed Central

    Shaevitz, Joshua W; Fletcher, Daniel A

    2011-01-01

    Intracellular pathogens such as Listeria monocytogenes and Rickettsia rickettsii move within a host cell by polymerizing a comet-tail of actin fibers that ultimately pushes the cell forward. This dense network of cross-linked actin polymers typically exhibits a striking curvature that causes bacteria to move in gently looping paths. Theoretically, tail curvature has been linked to details of motility by considering force and torque balances from a finite number of polymerizing filaments. Here we track beads coated with a prokaryotic activator of actin polymerization in three dimensions to directly quantify the curvature and torsion of bead motility paths. We find that bead paths are more likely to have low rather than high curvature at any given time. Furthermore, path curvature changes very slowly in time, with an autocorrelation decay time of 200 s. Paths with a small radius of curvature, therefore, remain so for an extended period resulting in loops when confined to two dimensions. When allowed to explore a three-dimensional (3D) space, path loops are less evident. Finally, we quantify the torsion in the bead paths and show that beads do not exhibit a significant left- or right-handed bias to their motion in 3D. These results suggest that paths of actin-propelled objects may be attributed to slow changes in curvature, possibly associated with filament debranching, rather than a fixed torque. PMID:18560043

  1. Curvature and torsion in growing actin networks

    NASA Astrophysics Data System (ADS)

    Shaevitz, Joshua W.; Fletcher, Daniel A.

    2008-06-01

    Intracellular pathogens such as Listeria monocytogenes and Rickettsia rickettsii move within a host cell by polymerizing a comet-tail of actin fibers that ultimately pushes the cell forward. This dense network of cross-linked actin polymers typically exhibits a striking curvature that causes bacteria to move in gently looping paths. Theoretically, tail curvature has been linked to details of motility by considering force and torque balances from a finite number of polymerizing filaments. Here we track beads coated with a prokaryotic activator of actin polymerization in three dimensions to directly quantify the curvature and torsion of bead motility paths. We find that bead paths are more likely to have low rather than high curvature at any given time. Furthermore, path curvature changes very slowly in time, with an autocorrelation decay time of 200 s. Paths with a small radius of curvature, therefore, remain so for an extended period resulting in loops when confined to two dimensions. When allowed to explore a three-dimensional (3D) space, path loops are less evident. Finally, we quantify the torsion in the bead paths and show that beads do not exhibit a significant left- or right-handed bias to their motion in 3D. These results suggest that paths of actin-propelled objects may be attributed to slow changes in curvature, possibly associated with filament debranching, rather than a fixed torque.

  2. Infrared modified gravity with dynamical torsion

    SciTech Connect

    Nikiforova, V.; Randjbar-Daemi, S.; Rubakov, V.

    2009-12-15

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

  3. Torsion and noninertial effects on a nonrelativistic Dirac particle

    SciTech Connect

    Bakke, K.

    2014-07-15

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

  4. Microstructure and Microtexture Evolution of Pure Titanium during Single Direction Torsion and Alternating Cyclic Torsion

    NASA Astrophysics Data System (ADS)

    Chen, Han; Li, Fuguo; Liu, Jie; Li, Jinghui; Ma, Xinkai; Wan, Qiong

    2017-03-01

    Systematic experimental studies of microstructure and crystallographic texture of pure titanium during the Single Direction Torsion (SDT) and Alternating Cyclic Torsion (ACT) are carried out at room temperature. The microstructure evolution indicates that the grain size can be refined during SDT, while the grain morphology can be controlled during ACT. Also, lots of {10-12} and few {11-22} twins are observed and their area percentages increase with increasing torsion angles during SDT. The microtexture evolution states that the deformation texture first approaches to the B fiber (0, 90, 0 to 60 deg), and then stays away from B fiber (0, 90, 0 to 60 deg) with increasing plastic strain during SDT. The change of deformation texture is mainly attributed to the appearance of {10-12} twin. However, the deformation texture is always close to B fiber (0, 90, 0 to 60 deg) during ACT. Finally, the effects of different dislocation movements caused by SDT and ACT are discussed. Quantities of subgrains with high density dislocation are observed during SDT while the {10-12} and {11-22} twins intersect with each other, and high density dislocations distribute the twin during ACT.

  5. Torsional suspension system for testing space structures

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  6. Plant-based torsional actuator with memory

    NASA Astrophysics Data System (ADS)

    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.

  7. Torsional thrust stand for characterization of microthrusters

    NASA Astrophysics Data System (ADS)

    Cheah, K. H.; Low, K. S.

    2016-10-01

    This paper describes the setup of a precise thrust stand based on torsional pendulum design for characterizing the performance of microthrusters. Calibration has been carried out by using an improved version of electrostatic calibrator, which produces a wide range of accurate and repeatable calibration force. After the calibration, the thrust stand can resolve constant force from 40μN to 3.4mN and impulse bit from 7μNs to 340μNs. The usefulness of the thrust stand has been demonstrated by measuring the performance of two different microthrusters: a pulsed plasma thruster that produces impulse bit of 23.15μNs and a vaporizing liquid microthruster that produces steady state thrust of 633.5μN.

  8. Experimental Study of Torsional Column Failure

    NASA Technical Reports Server (NTRS)

    Nile, Alfred S

    1939-01-01

    Thirty-three 24ST aluminum-alloy 2- by 2- by 0.10-inch channels, with lengths ranging from 10 to 90 inches were tested at Stanford University in compression to obtain an experimental verification of the theoretical formulas for torsional failure developed by Eugene E. Lundquist of the N.A.C.A. The observed critical loads and twist-axis locations were sufficiently close to the values obtained from the formulas to establish the substantial validity of the latter. The differences between observed and computed results were small enough to be accounted for by small and mostly unavoidable differences between actual test conditions and those assumed in deriving the formulas. Some data were obtained from the shorter specimens regarding the growth of the buckles that resulted in local buckling failure.

  9. Torsional ultrasonic transducer computational design optimization.

    PubMed

    Melchor, J; Rus, G

    2014-09-01

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

  10. Torsion Tests of Stiffened Circular Cylinders

    NASA Technical Reports Server (NTRS)

    Moore, R L; Wescoat, C

    1944-01-01

    The design of curved sheet panels to resist shear involves a consideration of several factors: the buckling resistance of the sheet, the stress at which buckling becomes permanent, and the strength which may be developed beyond the buckling limit by tension-field action. Although some experimental as well as theoretical work has been done on the buckling and tension-field phases of this problem, neither of these types of action appears to be very well understood. The problem is of sufficient importance from the standpoint of aircraft design, it is believed, to warrant further experimental investigation. This report presents the results of the first series of torsion tests of stiffened circular cylinders to be completed in connection with this study at Aluminum Research Laboratories. (author)

  11. Primordial magnetic fields and dynamos from parity violated torsion

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2012-05-01

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

  12. Management of suspected antenatal torsion: what is the best strategy?

    PubMed

    Stone, K T; Kass, E J; Cacciarelli, A A; Gibson, D P

    1995-03-01

    Currently, management of the newborn with suspected antenatal torsion is somewhat controversial. Many surgeons recommend early surgical exploration within the first few days of life, primarily to avoid errors in diagnosis. However, since the surgical and general anesthetic risks at this age are increased, it might be preferable to defer an operation until risks to the patient are minimized. The optimal solution to this dilemma would be the ability to diagnose torsion and exclude other conditions noninvasively. We present a series of 12 patients 1 to 14 days old who presented with a scrotal mass secondary to suspected antenatal testis torsion. Color Doppler ultrasound in each case demonstrated abnormal testicular blood flow and architecture consistent with testis torsion. Eventual exploration of all 12 patients confirmed prenatal torsion. We conclude that scrotal ultrasound with color Doppler enhancement can accurately identify neonates with antenatal testis torsion and exclude other scrotal pathological conditions. If elected, surgery for torsion can then be deferred until the risks of anesthesia and surgery are improved.

  13. Constraining spacetime torsion with the Moon and Mercury

    SciTech Connect

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

    2011-05-15

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

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

    PubMed

    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.

  15. Activation of Corticostriatal Circuitry Relieves Chronic Neuropathic Pain

    PubMed Central

    Lee, Michelle; Manders, Toby R.; Eberle, Sarah E.; Su, Chen; D'amour, James; Yang, Runtao; Lin, Hau Yueh; Deisseroth, Karl; Froemke, Robert C.

    2015-01-01

    Neural circuits that determine the perception and modulation of pain remain poorly understood. The prefrontal cortex (PFC) provides top-down control of sensory and affective processes. While animal and human imaging studies have shown that the PFC is involved in pain regulation, its exact role in pain states remains incompletely understood. A key output target for the PFC is the nucleus accumbens (NAc), an important component of the reward circuitry. Interestingly, recent human imaging studies suggest that the projection from the PFC to the NAc is altered in chronic pain. The function of this corticostriatal projection in pain states, however, is not known. Here we show that optogenetic activation of the PFC produces strong antinociceptive effects in a rat model (spared nerve injury model) of persistent neuropathic pain. PFC activation also reduces the affective symptoms of pain. Furthermore, we show that this pain-relieving function of the PFC is likely mediated by projections to the NAc. Thus, our results support a novel role for corticostriatal circuitry in pain regulation. PMID:25834050

  16. Use of opioid pain relievers following extraction of third molars.

    PubMed

    Weiland, Breanna M; Wach, Anthony G; Kanar, Brent P; Castele, Matthew T; Sosovicka, Mark F; Cooke, Matthew R; Moore, Paul A

    2015-02-01

    Following extraction of third molars, it is common practice for oral and maxillofacial surgeons to provide a prescription for an opioid-containing analgesic such as hydrocodone with acetaminophen. Because the instructions for use most often indicate that these analgesics are to be taken "as needed for pain," it is unknown how many of the prescribed postoperative analgesic tablets are needed and actually taken. Therefore, an assessment of patient pain experiences and actual opioid analgesic usage was carried out using structured telephone interviews of patients performed 1 and 7 days following their thirdmolar extraction surgery. Forty-eight adolescents and young adults, ages 15 to 30 years, participated in this assessment. A review of the surgeon's notes indicated that the median number of prescribed opioid-containing analgesics (ie, Vicodin®, Norco®, Lorcet®, Percocet®) was 20 tablets (range 10 to 40). The median consumption during the first 24 hours was reported to be three tablets (range 0 to 10), and the total consumption for all 7 days was eight tablets (range 0 to 34). Four patients reported nausea or vomiting in the first 24 hours, and six patients reported nausea or vomiting during the following 6 days of recovery. The initial prescriptions provided adequate relief for 45 of the 48 patients. Higher consumption of opioid pain relievers (OPRs) was associated with a longer duration of surgery and the occurrence of postoperative infections.

  17. Relieving patients' pain with expectation interventions: a meta-analysis.

    PubMed

    Peerdeman, Kaya J; van Laarhoven, Antoinette I M; Keij, Sascha M; Vase, Lene; Rovers, Maroeska M; Peters, Madelon L; Evers, Andrea W M

    2016-06-01

    Patients' expectations are important predictors of the outcome of analgesic treatments, as demonstrated predominantly in research on placebo effects. Three commonly investigated interventions that have been found to induce expectations (verbal suggestion, conditioning, and mental imagery) entail promising, brief, and easy-to-implement adjunctive procedures for optimizing the effectiveness of analgesic treatments. However, evidence for their efficacy stems mostly from research on experimentally evoked pain in healthy samples, and these findings might not be directly transferable to clinical populations. The current meta-analysis investigated the effects of these expectation inductions on patients' pain relief. Five bibliographic databases were systematically searched for studies that assessed the effects of brief verbal suggestion, conditioning, or imagery interventions on pain in clinical populations, with patients experiencing experimental, acute procedural, or chronic pain, compared with no treatment or control treatment. Of the 15,955 studies retrieved, 30 met the inclusion criteria, of which 27 provided sufficient data for quantitative analyses. Overall, a medium-sized effect of the interventions on patients' pain relief was observed (Hedges g = 0.61, I = 73%), with varying effects of verbal suggestion (k = 18, g = 0.75), conditioning (always paired with verbal suggestion, k = 3, g = 0.65), and imagery (k = 6, g = 0.27). Subset analyses indicated medium to large effects on experimental and acute procedural pain and small effects on chronic pain. In conclusion, patients' pain can be relieved with expectation interventions; particularly, verbal suggestion for acute procedural pain was found to be effective.

  18. Relieving Pain using Dose-Extending Placebos: A Scoping Review

    PubMed Central

    Colloca, Luana; Enck, Paul; DeGrazia, David

    2017-01-01

    Placebos are often used by clinicians, usually deceptively and with little rationale or evidence of benefit, making their use ethically problematic. In contrast with their typical current use, a provocative line of research suggests that placebos can be intentionally exploited to extend analgesic therapeutic effects. Is it possible to extend the effects of drug treatments by interspersing placebos? We reviewed a database of placebo studies, searching for studies that indicate that placebos given after repeated administration of active treatments acquire medication-like effects. We found a total of 22studies in both animals and humans hinting of evidence that placebos may work as a sort of dose extender of active painkillers. Wherever effective in relieving clinical pain, such placebo use would offer several advantages. First, extending the effects of a painkiller through the use of placebos may reduce total drug intake and side effects. Second, dose-extending placebos may decrease patient dependence. Third, using placebos along with active medication, for part of the course of treatment, should limit dose escalation and lower costs. Importantly, provided that nondisclosure is pre-authorized in the informed consent process and that robust evidence indicates therapeutic benefit comparable to that of standard full-dose therapeutic regimens, introducing dose-extending placebos into the clinical arsenal should be considered. This novel prospect of placebo use has the potential to change our general thinking about painkiller treatments, the typical regimens of painkiller applications, and the ways in which treatments are evaluated. PMID:27023425

  19. Relieving pain using dose-extending placebos: a scoping review.

    PubMed

    Colloca, Luana; Enck, Paul; DeGrazia, David

    2016-08-01

    Placebos are often used by clinicians, usually deceptively and with little rationale or evidence of benefit, making their use ethically problematic. In contrast with their typical current use, a provocative line of research suggests that placebos can be intentionally exploited to extend analgesic therapeutic effects. Is it possible to extend the effects of drug treatments by interspersing placebos? We reviewed a database of placebo studies, searching for studies that indicate that placebos given after repeated administration of active treatments acquire medication-like effects. We found a total of 22 studies in both animals and humans hinting of evidence that placebos may work as a sort of dose extender of active painkillers. Wherever effective in relieving clinical pain, such placebo use would offer several advantages. First, extending the effects of a painkiller through the use of placebos may reduce total drug intake and side effects. Second, dose-extending placebos may decrease patient dependence. Third, using placebos along with active medication, for part of the course of treatment, should limit dose escalation and lower costs. Provided that nondisclosure is preauthorized in the informed consent process and that robust evidence indicates therapeutic benefit comparable to that of standard full-dose therapeutic regimens, introducing dose-extending placebos into the clinical arsenal should be considered. This novel prospect of placebo use has the potential to change our general thinking about painkiller treatments, the typical regimens of painkiller applications, and the ways in which treatments are evaluated.

  20. New pain-relieving strategies for topical photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Halldin, Christina B.; Paoli, John; Sandberg, Carin; Ericson, Marica B.; Gonzalez, Helena; Wennberg, Ann-Marie

    2009-06-01

    PDT is an effective method when treating multiple actinic keratoses (field cancerization). The major side effect is pain. Our objectives were to investigate the pain-relieving effect of transcutaneous electrical nerve stimulation (TENS) and peripheral nerve blocks during PDT of field cancerization (FC) of the face and scalp. Patients with field cancerization were included in three studies. In the first study, we examined TENS with an application site on the adjacent dermatome from the PDT area in order to allow the use of water spray during PDT for FC of the scalp and face. In the second study, patients with FC in the facial area received unilateral supraorbital, infraorbital and/or mental nerve blocks. The non-anaesthetised side of the treatment area served as control. In the third study, with similar methodology as in the second study, occipital and supraorbital nerve blocks were combined for FC of the forehead and scalp. The results of the studies strongly support the use of nerve blocks as pain relief during PDT. The use of TENS provided a limited pain reduction, but TENS might be an alternative if the patient disapproves of the use of nerve blocks or is afraid of injections.

  1. Torsion constraints from cosmological magnetic field and QCD domain walls

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2014-10-01

    Earlier Kostelecky [Phys. Rev. D 69, 105009 (2004)] has investigated the role of gravitational sector in Riemann-Cartan (RC) spacetime with torsion, in Lorentz and CPT violating (LV) Standard Model extension (SME). In his paper use of quantum electrodynamic (QED) extension in RC spacetime is made. More recently L. C. Garcia de Andrade [Phys. Lett. B 468, 28 (2011)] obtained magnetic field galactic dynamo seeds in the bosonic sector with massless photons, which proved to decay faster than necessary [Phys. Lett. B 711, 143 (2012)] to be able to seed galactic dynamos. In this paper it is shown that by using the fermionic sector of Kostelecky-Lagrangian and torsion written as a chiral current, one obtains torsion and magnetic fields explicitly from a Heisenberg-Ivanenko form of Dirac equation whose solution allows us to express torsion in terms of LV coefficients and magnetic field in terms of fermionic matter fields. When minimal coupling between electromagnetic and torsion fields is used it is shown that the fermionic sector of QED with torsion leads to resonantly amplify magnetic fields which mimics an α2-dynamo mechanism. Fine-tuning of torsion is shown to result in the dynamo reversal, a phenomenon so important in solar physics and geophysics. Of course this is only an analogy since torsion is very weak in solar and geophysics contexts. An analogous expression for the α-effect of mean-field dynamos is also obtained where the α-effect is mimic by torsion. Similar resonant amplification mechanisms connected to early universe have been considered by Finelli and Gruppuso.

  2. Validation of an Automated Torsional and Warping Stress Analysis Program

    DTIC Science & Technology

    1992-08-19

    AD-A256 035 I HEI| I IIHAI l! VALIDATION OF AN AUTOMATED TORSIONAL AND WARPING STRESS ANALYSIS PROGRAM DI f ELECTE ND OCT 8 1992 A Special Research...7 2.2 Torsional Analysis Case Charts ....................... 8 2.3 Determination of Plane Bending, Torsional ............. 9 and Warping...Fixed-Free 6 W1Ox49 Fixed-Free 7 W6x15 Fixed-Free 8 W8x67 Fixed-Free 9 ClOx20 Fixed-Free 10 C12x30 Fixed-Free 11 C5x9 Fixed-Fire 12 MC18x42 Fixed-Free

  3. Torsional anharmonicity in the conformational thermodynamics of flexible molecules

    NASA Astrophysics Data System (ADS)

    Miller, Thomas F., III; Clary, David C.

    We present an algorithm for calculating the conformational thermodynamics of large, flexible molecules that combines ab initio electronic structure theory calculations with a torsional path integral Monte Carlo (TPIMC) simulation. The new algorithm overcomes the previous limitations of the TPIMC method by including the thermodynamic contributions of non-torsional vibrational modes and by affordably incorporating the ab initio calculation of conformer electronic energies, and it improves the conventional ab initio treatment of conformational thermodynamics by accounting for the anharmonicity of the torsional modes. Using previously published ab initio results and new TPIMC calculations, we apply the algorithm to the conformers of the adrenaline molecule.

  4. Spinning Particles in Scalar-Tensor Gravity with Torsion

    SciTech Connect

    Wang, C.-H.

    2008-10-10

    A new model of neutral spinning particles in scalar-tensor gravity with torsion is developed by using a Fermi coordinates associated with orthonormal frames attached to a timelike curve and Noether identities. We further analyze its equations of motion both in background Brans-Dicke torsion field and the constant pseudo-Riemannian curvature with a constant scalar field. It turns that the particle's spin vector is parallel transport along its wordline in the Brans-Dicke torsion field and de Sitter spacetime. However, the dynamics of the spinning particle cannot completely determined in anti-de Sitter spacetime and it requires a further investigation.

  5. Experimental investigation of cyclic thermomechanical deformation in torsion

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    PubMed

    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.

  7. Acute torsion of wandering spleen: report of one case.

    PubMed

    Lien, Chi-Hone; Lee, Hung-Chang; Yeung, Chun-Yan; Chan, Wai-Tao; Wang, Nein-Lu

    2009-08-01

    Wandering spleen is a rare condition that can lead to splenic infarction or rupture if torsion persists. Early diagnosis and intervention are necessary, and abdominal ultrasonography and abdominal computed tomography are well accepted as the diagnostic imaging modalities. In this study, we present a boy with nic infarction due to acute torsion of a wandering spleen, after initial failure to demonstrate an ectopic spleen. Instead, acute torsion of the wandering spleen with spontaneous partial detorsion was incidentally found by multi-detector row CT with angiography. The patient was managed by splenectomy instead of splenopexy, because poor reperfusion after Laparoscopic detorsion.

  8. Discussion on massive gravitons and propagating torsion in arbitrary dimensions

    SciTech Connect

    Hernaski, C. A.; Vargas-Paredes, A. A.; Helayeel-Neto, J. A.

    2009-12-15

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

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Self-administered pain-relieving manoeuvres in primary headaches.

    PubMed

    Zanchin, G; Maggioni, F; Granella, F; Rossi, P; Falco, L; Manzoni, G C

    2001-09-01

    We investigated the use of self-administered pain-relieving manoeuvres on a sample of 400 patients with primary headaches--represented by an even distribution of migraine without aura (MO), migraine with aura (MA), episodic tension-type headache (TH), and cluster headache (CH)--consecutively seen at Padua and Parma Headache Centres. Manoeuvres on various regions of the head were used by 258 patients (65% of the cases). The most applied procedures were: compression (114 out of 382 manoeuvres; 30%), application of cold (27%), massage (25%) and application of heat (8%). A significant (P < 0.001) relationship was found between headache diagnoses and type of manoeuvre. In MO patients the application of cold (38% of the manoeuvres) and compression (36%), used mainly on the forehead and temples, prevailed; compression, mainly on the temples, was the most frequent procedure (44%) in MA patients. Massage on the temples and nape was the predominant manoeuvre (43%) in TH patients, whereas in the CH group, which more often required heterogeneous procedures, none of the above-mentioned manoeuvres was prevalent. Compression, as a diagnostic criterion for MO, had a sensitivity of 33% and a specificity of 86%; for the application of cold the figures were 36% and 84%, respectively. Massage had a sensitivity of 33% and a specificity of 80% for TH. The efficacy of the self-administered manoeuvres in reducing pain was scarce. Only 8% of the manoeuvres, in fact, resulted in a good or excellent pain control. Moreover, the efficacy of the manoeuvre was often momentary, wearing off when the manoeuvre stopped. In spite of this, 46% of the subjects used the manoeuvres constantly, at each attack.

  11. Efficacy of Carbon Microcoils in Relieving Cervicogenic Dizziness

    PubMed Central

    Bittar, Roseli; Alves, Nédison Gomes Paim; Bertoldo, César; Brugnera, Cibele; Oiticica, Jeanne

    2016-01-01

    Introduction Cervical pain contributes to postural deviations and imbalance. Nanotechnology may be used for the treatment of neck pain by fixing to the skin small rounds silicone patches containing double spiral carbon nanotubes arranged in the form of a coil (Helical), which would then relieve dizziness caused by muscular contraction. Objective The objective of this study is to Evaluate pain and dizziness scores before and after Helical patches effect on cervicogenic dizziness treatment. Methods The selected patients should have neck pain arising from muscle contraction with loss of balance or instability lasting more than 90 days and normal electrooculography. Treatment consisted of placing 10 Helical patches distributed as follows: two in the upper cervical area, two in the lower cervical area (near the 5th and 6th vertebrae), two in the upper trapezius muscle area (between neck and shoulder), and four in the tender point area (as reported by the patient). Using a Visual Analogue Scale (VAS), we matched pain and dizziness scores from Day 1 to those from Day 15 and Day 30 using Mann-Whitney test. Results There was a significant difference between pain score reported on Day 1 and Day 15 (Z = 2.43, U = 5, p = 0.01). We also found significant differences between dizziness scores reported on days 1 and 15 (Z = 2.62, U = 3.5, p = 0.01) and days 1 and 30 (Z = 2.36, U = 5.5, p = 0.01). Conclusion The Helical patches seem to be an effective treatment for cervicogenic dizziness. PMID:28050200

  12. 49 CFR 192.201 - Required capacity of pressure relieving and limiting stations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Design of Pipeline Components § 192.201 Required capacity of pressure relieving and limiting stations. (a) Each pressure relief station or pressure limiting station or group of those stations installed to... 49 Transportation 3 2010-10-01 2010-10-01 false Required capacity of pressure relieving...

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Structural and torsional vibration analysis of a dry screw compressor

    NASA Astrophysics Data System (ADS)

    Willie, J.; Sachs, R.

    2015-08-01

    This paper investigates torsional vibration and pulsating noise in a dry screw compressor. The compressor is designed at Gardner Denver (GD) and is oil free and use for mounting on highway trucks. They are driven using a Power Take-Off (PTO) transmission and gear box on a truck. Torque peak fluctuation and noise measurements are done and their sources are investigated and reported in this work. To accurately predict the torsional response (frequency and relative angular deflection and torque amplitude), the Holzer method is used. It is shown that the first torsional frequency is manifested as sidebands in the gear train meshing frequencies and this can lead to noise that is the result of amplitude modulation. Sensitivity analysis of the drive train identifies the weakest link in the drive train that limits the first torsional frequency to a low value. Finally, the significance of higher mode shapes on inter-lobe clearance distribution of the rotors is investigated.

  15. Response characteristics of the human torsional vestibuloocular reflex

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.

    1992-01-01

    The characteristics of the response dynamics of the human torsional vestibuloocular reflex were studied during controlled rotations about an earth-horizontal axis. The results extended the frequency range to 2 Hz and identified the nonlinearity of the amplitude response.

  16. Torsional Newton-Cartan geometry from Galilean gauge theory

    NASA Astrophysics Data System (ADS)

    Banerjee, Rabin; Mukherjee, Pradip

    2016-11-01

    Using the recently advanced Galilean gauge theory (GGT) we give a comprehensive construction of torsional Newton-Cartan (NC) geometry. The coupling of a Galilean symmetric model with background NC geometry following GGT is illustrated by a free nonrelativistic scalar field theory. The issue of spatial diffeomorphism (Son and Wingate 2006 Ann. Phys. 321 197-224 Banerjee et al 2015 Phys. Rev. D 91 084021) is focussed from a new angle. The expression of the torsionful connection is worked out, which is in complete parallel with the relativistic theory. Also, smooth transition of the connection to its well known torsionless expression is demonstrated. A complete (implicit) expression of the torsion tensor for the NC spacetime is provided where the first-order variables occur in a suggestive way. The well known result for the temporal part of torsion is reproduced from our expression.

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

    PubMed

    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.

  18. Bilateral perinatal testicular torsion: successful salvage supports emergency surgery.

    PubMed

    Granger, Jeremy; Brownlee, Ewan M; Cundy, Thomas P; Goh, Day Way

    2016-06-15

    Perinatal testicular torsion (PTT) has poor rates of testicular salvage. Although rare, bilateral PTT carries the risk of anorchia. We present a case of a 2-day-old term infant with acute onset right-sided scrotal discolouration and tenderness. The infant was promptly taken to the operating theatre for emergency scrotal exploration. Bilateral extravaginal testicular torsion was identified, with the right testis appearing to have a more established ischaemic appearance compared to that on the left side. Intraoperative findings were representative of metachronous PTT with a short time period of only several hours separating the torsion events. Both testes were detorted and fixated in the scrotum. The infant made an uneventful recovery. Outpatient clinic review at 6 weeks and 6 months postoperatively confirmed no clinical evidence of testicular atrophy. Given the potential for contralateral torsion and the morbidity of anorchia, our experience supports the role for emergency scrotal exploration in suspected PTT.

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

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.; Gutlé, C.; Huet, T. R.; Grabow, J.-U.; Levshakov, S. A.

    2015-07-01

    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.

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

    SciTech Connect

    Coudert, L. H. Gutlé, C.; Huet, T. R.; Grabow, J.-U.; Levshakov, S. A.

    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.

  1. An Inexpensive Torsional Pendulum Apparatus for Rigidity Modulus Measurement.

    ERIC Educational Resources Information Center

    Tyagi, S.; Lord, A. E., Jr.

    1979-01-01

    Described is an easy to assemble, and inexpensive, torsional pendulum which gives an accuracy of measurement of the modulus of rigidity, G, comparable to the accuracy obtained with the more expensive commercially available student models. (Author/GA)

  2. Torsion of the Appendix Testis in a Neonate

    PubMed Central

    Krishnan, Arvind; Rich, Mark A.; Swana, Hubert S.

    2016-01-01

    Torsion of the appendix testis is a rare cause of scrotal swelling in the neonatal period. We present a case of torsion of the appendix testis in a one-day-old male. We discuss the physical examination and radiologic studies used to make the diagnosis. Nonoperative therapy was recommended and the patient has done well. Recognition of this condition in the neonatal period can prevent surgical intervention and its associated risks. PMID:27379193

  3. Cosmic Magnetic Fields from Torsion Modes and Massive Photon Inflation

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2014-09-01

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

  4. Salvage splenopexy for torsion of wandering spleen in a child.

    PubMed

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

    2014-01-01

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

  5. Salvage Splenopexy for Torsion of Wandering Spleen in a Child

    PubMed Central

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

    2014-01-01

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

  6. Thermal conductivity and torsional oscillations of solid 4He

    NASA Astrophysics Data System (ADS)

    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 < 10-10, commercial `well-grade' helium with x3 ˜ 3.10-7 and a mixture with x3 = 2.5.10-6. Torsional oscillations at two frequencies, 132.5 and 853.6 Hz, and thermal conductivity were investigated before and after annealing. The solid helium under investigation was located not only in the annular container but also in the axial fill line inside two torsion rods and 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.

  7. Torsional texturing of superconducting oxide composite articles

    DOEpatents

    Christopherson, Craig John; Riley, Jr., Gilbert N.; Scudiere, John

    2002-01-01

    A method of texturing a multifilamentary article having filaments comprising a desired oxide superconductor or its precursors by torsionally deforming the article is provided. The texturing is induced by applying a torsional strain which is at least about 0.3 and preferably at least about 0.6 at the surface of the article, but less than the strain which would cause failure of the composite. High performance multifilamentary superconducting composite articles having a plurality of low aspect ratio, twisted filaments with substantially uniform twist pitches in the range of about 1.00 inch to 0.01 inch (25 to 0.25 mm), each comprising a textured desired superconducting oxide material, may be obtained using this texturing method. If tighter twist pitches are desired, the article may be heat treated or annealed and the strain repeated as many times as necessary to obtain the desired twist pitch. It is preferred that the total strain applied per step should be sufficient to provide a twist pitch tighter than 5 times the diameter of the article, and twist pitches in the range of 1 to 5 times the diameter of the article are most preferred. The process may be used to make a high performance multifilamentary superconducting article, having a plurality of twisted filaments, wherein the degree of texturing varies substantially in proportion to the radial distance from the center of the article cross-section, and is substantially radially homogeneous at any given cross-section of the article. Round wires and other low aspect ratio multifilamentary articles are preferred forms. The invention is not dependent on the melting characteristics of the desired superconducting oxide. Desired oxide superconductors or precursors with micaceous or semi-micaceous structures are preferred. When used in connection with desired superconducting oxides which melt irreversibly, it provides multifilamentary articles that exhibit high DC performance characteristics and AC performance markedly

  8. An Axial-Torsional, Thermomechanical Fatigue Testing Technique

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Bonacuse, Peter J.

    1995-01-01

    A technique for conducting strain-controlled, thermomechanical, axial-torsional fatigue tests on thin-walled tubular specimens was developed. Three waveforms of loading, namely, the axial strain waveform, the engineering shear strain waveform, and the temperature waveform were required in these tests. The phasing relationships between the mechanical strain waveforms and the temperature and axial strain waveforms were used to define a set of four axial-torsional, thermomechanical fatigue (AT-TMF) tests. Real-time test control (3 channels) and data acquisition (a minimum of 7 channels) were performed with a software program written in C language and executed on a personal computer. The AT-TMF testing technique was used to investigate the axial-torsional thermomechanical fatigue behavior of a cobalt-base superalloy, Haynes 188. The maximum and minimum temperatures selected for the AT-TMF tests were 760 and 316 C, respectively. Details of the testing system, calibration of the dynamic temperature profile of the thin-walled tubular specimen, thermal strain compensation technique, and test control and data acquisition schemes, are reported. The isothermal, axial, torsional, and in- and out-of-phase axial-torsional fatigue behaviors of Haynes 188 at 316 and 760 C were characterized in previous investigations. The cyclic deformation and fatigue behaviors of Haynes 188 in AT-TMF tests are compared to the previously reported isothermal axial-torsional behavior of this superalloy at the maximum and minimum temperatures.

  9. Testicular torsion, oxidative stress and the role of antioxidant therapy.

    PubMed

    Dokmeci, Dikmen

    2006-01-01

    Testicular torsion is a urological syndrome caused mainly by a twist in the spermatic cord. It constitutes a surgical emergency and affects newborns, children and adolescent boys. The torsion must be treated promptly to avoid loss of function of ipsilateral and contralateral testis. This syndrome often leads to infertility of the ipsilateral (torted) and contralateral (not torted) testis,but the mechanisms of cellular injury remain still incompletely understood. The primary pathophysiologic event in testicular torsion is ischemia followed by reperfusion; thus, testicular torsion/detorsion is an ischemia/reperfusion (I/R) injury to the testis. Testicular torsion and detorsion causes morphological and biochemical changes by both ischemia and reperfusion of the tissues. These I/R injury is associated with overgeneration of reactive oxygen species (ROS) and reactive nitrogen species (RNS), and also with a common mechanism to other organs such as brain, heart and kidneys. Although the results are not conclusive and the molecular mechanism by which antioxidants control male fertility have not yet been clearly identified, several antioxidant enzymes and antioxidant drugs have been studied to prevent such I/R injury in testis. As a result, antioxidant therapy may represent a new non-hormonal option within a broader therapeutic strategy in men with ROS-mediated infertility such as testicular torsion.

  10. Control of Torsional Vibrations by Pendulum Masses

    NASA Technical Reports Server (NTRS)

    Stieglitz, Albert

    1942-01-01

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

  11. Association between pregnancy and adnexal torsion

    PubMed Central

    Yuk, Jin-Sung; Shin, Ji-Yeon; Park, Won I.; Kim, Dae Woon; Shin, Jung Whan; Lee, Jung Hun

    2016-01-01

    Abstract The purpose of this study was to determine the effect of pregnancy on adnexal torsion (AT). We conducted a matched case-control study using the Korean Health Insurance Review and Assessment Service–National Inpatients Sample (HIRA-NIS) from 2009 to 2011. AT patients were defined as women with both a diagnostic code (N835) and a surgical code for AT. The AT patients were randomly matched 1:4 with women without AT by age and year of claim. In total, 545 AT cases and 2180 controls were enrolled from a total of 1,843,451 women. After adjustment for such covariates as age, pregnancy was found to be associated with a lower rate of AT (adjusted odds ratio 0.314, 95% confidence interval [CI] 0.237–0.416, P value <0.01) and ovarian hyperstimulation syndrome was associated with a higher rate of AT (adjusted odds ratio 20.091, 95% CI 3.607–111.908, P value <0.01). We found that pregnancy is a negative risk factor for AT. However, a further study is needed to elucidate the mechanisms underlying these results. PMID:27310967

  12. Torsion-vibration coupling in S1 toluene: Implications for IVR, the torsional barrier height, and rotational constants.

    PubMed

    Gascooke, Jason R; Virgo, Edwina A; Lawrance, Warren D

    2015-07-28

    We have examined the S1←S0 transition of toluene in the region from the 0(0)(0) band to ∼210 cm(-1) above it. The spectrum reveals methyl rotor levels of 0(0) toluene up to m = 6 and of the lowest frequency vibration, 20(1), up to m = 4. The rotor levels of both 20(1) and 0(0) are perturbed by torsion-vibration coupling. The inclusion of torsion-vibration coupling leads to the S1 torsional barrier, V6, being revised from -26.376 cm(-1) to -5.59 cm(-1). The torsion-vibration coupling constant is determined to be 21.1 cm(-1). This situation is the S1 analogue of that recently reported for S0 toluene [Gascooke et al., J. Chem. Phys. 142, 024315 (2015)]. Torsion-vibration coupling alters both the rotor band positions and the rotational contours, which particularly affects the rotational constants associated with motion around the a-axis, about which the methyl group rotates. Every vibrational state (indicated generically by X) will be involved in the corresponding X - X20(1) torsion-vibration coupling; so, this interaction permeates the vib-rotor manifold, providing a mechanism to enhance intramolecular vibrational energy redistribution.

  13. Scrotal Exploration for Testicular Torsion and Testicular Appendage Torsion: Emergency and Reality

    PubMed Central

    Yu, You; Zhang, Feng; An, Qun; Wang, Long; Li, Chao; Xu, Zhilin

    2015-01-01

    Background: Scrotal exploration is considered the procedure of choice for acute scrotum. Objectives: We evaluated the importance of early diagnosis and testicular salvage on the therapeutic outcomes of patients with pediatric testicular torsion (TT) and testicular appendage torsion (TAT) in our geographic area. Patients and Methods: We performed a retrospective database analysis of patients who underwent emergency surgery for TT or TAT between January 1996 and June 2009. Patient history, physical examination findings, laboratory test results, color Doppler sonography (CDS) results, and surgical findings were reviewed. Results: A total of 65 cases were included in our analysis. Forty-two cases were followed up for at least 3 months. Testicular tenderness was identified as the major clinical manifestation of TT, while only a few patients with TAT presented with swelling. CDS was an important diagnostic modality. The orchiectomy rate was 71% in the TT group. Conclusions: Cases of acute scrotum require attention in our area. Early diagnosis and scrotal exploration could salvage the testis or preserve normal function without the need for surgery. PMID:26199690

  14. Does a Randall-Sundrum Scenario Create the Illusion of a Torsion-Free Universe?

    NASA Astrophysics Data System (ADS)

    Mukhopadhyaya, Biswarup; Sen, Somasri; Sengupta, Soumitra

    2002-08-01

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

  15. Early onset torsion dystonia (Oppenheim's dystonia)

    PubMed Central

    Kamm, Christoph

    2006-01-01

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

  16. Antiapoptotic effects of dehydroepiandrosterone on testicular torsion/detorsion in rats.

    PubMed

    Yapanoglu, T; Aksoy, Y; Gursan, N; Ozbey, I; Ziypak, T; Calik, M

    2008-02-01

    In the present study, we aimed to evaluate the effects of dehydroepiandrosterone (DHEA) on apoptosis of testicular germ cells after repair of testicular torsion in rats. Twenty-four adult male Sprague-Dawley rats were randomly divided into four groups, with six rats in each group: sham operation, torsion/detorsion (T/D), T/D + vehicle, and T/D + DHEA. Three hours before detorsion, 50 mg kg(-1) DHEA was given intraperitoneally to T/D + DHEA group. In all groups, bilateral orchiectomies were performed and both testicles were histologically examined, with apoptosis detected using the in situ DNA fragmentation [terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)] system, with morphological damage detected using a four-level grading scale in each specimen. The testes of the sham group showed a normal histology. In T/D and T/D + vehicle groups, apoptotic spermatogonia and spermatocyte number were significantly higher than in the sham group (P < 0.01 for all). The T/D + DHEA group showed a reduction in apoptotic spermatocyte and spermatogonia number in seminiferous epithelia compared with T/D group (P < 0.01 for both). Apoptotic cell number of contralateral testes did not reveal any significant differences among these groups (P > 0.05). Specimens from T/D and T/D + vehicle had a significantly greater histological injury than sham and T/D + DHEA groups in the ipsilateral testes (P < 0.01 for both). Therefore, the results suggest that DHEA may be a protective agent for preventing apoptosis caused by testicular torsion.

  17. Structural diversity of supercoiled DNA

    PubMed Central

    Irobalieva, Rossitza N.; Fogg, Jonathan M.; Catanese, Daniel J.; Sutthibutpong, Thana; Chen, Muyuan; Barker, Anna K.; Ludtke, Steven J.; Harris, Sarah A.; Schmid, Michael F.; Chiu, Wah; Zechiedrich, Lynn

    2015-01-01

    By regulating access to the genetic code, DNA supercoiling strongly affects DNA metabolism. Despite its importance, however, much about supercoiled DNA (positively supercoiled DNA, in particular) remains unknown. Here we use electron cryo-tomography together with biochemical analyses to investigate structures of individual purified DNA minicircle topoisomers with defined degrees of supercoiling. Our results reveal that each topoisomer, negative or positive, adopts a unique and surprisingly wide distribution of three-dimensional conformations. Moreover, we uncover striking differences in how the topoisomers handle torsional stress. As negative supercoiling increases, bases are increasingly exposed. Beyond a sharp supercoiling threshold, we also detect exposed bases in positively supercoiled DNA. Molecular dynamics simulations independently confirm the conformational heterogeneity and provide atomistic insight into the flexibility of supercoiled DNA. Our integrated approach reveals the three-dimensional structures of DNA that are essential for its function. PMID:26455586

  18. Optical fiber accelerometer based on MEMS torsional micromirror

    NASA Astrophysics Data System (ADS)

    Zeng, Fanlin; Zhong, Shaolong; Xu, Jing; Wu, Yaming

    2008-03-01

    A novel structure of optical fiber accelerometer based on MEMS torsional micro-mirror is introduced, including MEMS torsional micro-mirror and optical signal detection. The micro-mirror is a non-symmetric one, which means that the torsional bar supporting the micro-mirror is not located in the axis where the center of the micro-mirror locates. The optical signal detection is composed of PIN diode and dual fiber collimator, which is very sensitive to the coupling angle between the input fiber and output fiber. The detection principle is that acceleration is first transformed into torsional angle of the micro-mirror, then, optical insertion loss of the dual fiber collimator caused by the angle can be received by PIN. So under the flow of acceleration to torsional angle to optical signal attenuation to optical power detection, the acceleration is detected. The theory about sensing and optical signal detect of the device are discussed in this paper. The sensitive structure parameters and performance parameters are calculated by MATLAB. To simulate the static and modal analysis, the finite element analysis, ANSYS, is employed. Based on the above calculation, several optimization methods and the final structure parameters are given. The micro-mirror is completed by using silicon-glass bonding and deep reactive ion etching (DRIE). In the experiment, the acceleration is simulated by electrostatic force and the test results show that the static acceleration detection agrees with the theory analysis very well.

  19. The intermountain power project commissioning - Subsynchronous torsional interaction tests

    SciTech Connect

    Wu, C.T.; Peterson, K.J. ); Pinko, R.J.; Kankam, M.D.; Baker, D.H. )

    1988-10-01

    Subsyncronous torsional vibration as a result of electrochemical interaction between the HVDC controls and a turbine-generator was first discovered during the commissioning of the Square Butte Project in 1977. The level of interaction between the HVDC controls and the turbine-generator depends on several interacting factors: the characteristic torsional frequencies of the turbine-generator, the bandwidth of the HVDC controls and the relative strength of the connecting ac system. For the Intermountain Power Project (IPP), early analysis of these interacting factors indicated that there exist definite potential for subsynchronous oscillation to occur. The calculated torsional frequencies of the IPP units showed that the first mode frequency is 14.0 Hz and is within the typical bandwidth of an HVDC control which is between 10-20 Hz. The HVDC controls, therefore, can influence the torsional stability of the IPP units. Further, the IPP turbine-generators are required to operate isolated on the HVDC rectifier terminal, with no other interconnecting ac network. This ''radial'' mode of operation will result in maximum interaction between the converter station and the IPP units. It became obvious that special measure must be implemented in the design of the IPP HVDC control system to modify its typical characteristics to avoid the occurrence of the subsynchronous oscillation. This paper presents the results of the subsynchronous torsional interaction (SSTI) tests that were performed during the commissioning of the IPP Unit 1 and the HVDC Transmission system.

  20. A torsion quasi-zero stiffness vibration isolator

    NASA Astrophysics Data System (ADS)

    Zhou, Jiaxi; Xu, Daolin; Bishop, Steven

    2015-03-01

    A torsion vibration isolator with quasi-zero stiffness (QZS) is proposed to attenuate the transmission of torsional vibration along a shaft system, which also plays a role of coupling between shafts. A pre-compressed cam-roller mechanism is designed to provide torsional negative stiffness that counteracts with the positive torsion stiffness of the vulcanized rubber between shafts. With the design parameters are set to satisfy a unique condition, the stiffness of the isolator delivers a QZS property about the equilibrium position. A nonlinear mathematical model is developed and its dynamic characteristics are further analyzed by using the Harmonic Balance method. A typical folded resonance curve occurs when the vibration amplitude is plotted as the excitation frequency is varied, illustrating a jump phenomenon in the response. The efficiency of vibration attenuation is estimated under a designed torque load, showing that the torsion QZS vibration isolator outperforms the corresponding linear counterpart, especial in low frequency ranges. Furthermore, the torque transmissibility of the QZS isolator is also studied to demonstrate the performance of the QZS isolator when the actual torque deviates from the design load.

  1. Numerical modeling of pendulum dampers in torsional systems

    SciTech Connect

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

    1986-01-01

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

  2. [Torsion of wandering spleen in a teenager: about a case].

    PubMed

    Dème, Hamidou; Akpo, Léra Géraud; Fall, Seynabou; Badji, Nfally; Ka, Ibrahima; Guèye, Mohamadou Lamine; Touré, Mouhamed Hamine; Niang, El Hadj

    2016-01-01

    Wandering or migrating spleen is a rare anomaly which is usually described in children. Complications, which include pedicle torsion, are common and can be life-threatening. We report the case of a 17 year-old patient with a long past medical history of epigastric pain suffering from wandering spleen with chronic torsion of the pedicle. The clinical picture was marked by spontaneously painful epigastric mass, evolved over the past 48 hours. Abdominal ultrasound objectified heterogeneous hypertrophied ectopic spleen in epigastric position and a subcapsular hematoma. Doppler showed a torsion of splenic pedicle which was untwisted 2 turns and a small blood stream on the splenic artery. Abdominal CT scan with contrast injection showed a lack of parenchymal enhancement of large epigastric ectopic spleen and a subcapsular hematoma. The diagnosis of wandering spleen with chronic torsion of the pedicle complicated by necrosis and subcapsular hematoma was confirmed. The patient underwent splenectomy. The postoperative course was uneventful. We here discuss the contribution of ultrasound and CT scan in the diagnosis of wandering spleen with chronic torsion of the pedicle.

  3. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1995-01-01

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

  4. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1992-01-01

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

  5. Bending and torsional flexibility of G/C-rich sequences as determined by cyclization assays.

    PubMed

    Dlakic, M; Harrington, R E

    1995-12-15

    The structural polymorphism of DNA is a vital aspect of its biological function. However, it has become increasingly apparent in recent years that DNA polymorphism is a complicated, multidimensional phenomenon that includes not only static sequence-directed structures but dynamic effects as well, including influences of counterions and sequence context. In order to address some of these additional factors that govern DNA conformation, we have used T4 ligase-mediated cyclization to investigate bending in a series of DNA sequences containing the GGGCCC.GGGCCC motif in different sequence contexts including various helical phasings with (A)5-tracts. We present evidence for curvature in GGGCCC.GGGCCC and (A)5-tract motifs in the presence of physiological levels of Mg2+ and show that these motifs curve through similar but oppositely directed bending angles under these ionic strength conditions. Although these two sequence motifs appear to bend similarly, our results suggest significant differences in stiffness and stability of curvature between them. We also show that under the same experimental conditions, the CTAG-CTAG sequence element possesses unusual torsional flexibility and that this appears to be associated with the central TA.TA dinucleotide. The results underscore the need to include sequence context and specific ion effects as well as a dynamic basis in more complete predictive models for functionally related DNA polymorphism.

  6. Misuse of Prescription Pain Relievers: The Buzz Takes Your Breath Away. Permanently.

    MedlinePlus

    ... parents, doctors, relatives, teachers, or school guidance counselors. Substance abuse ruins lives. Don't let it happen to ... is hooked on prescription pain relievers, call the substance abuse treatment 24-hour helpline: 1.800.662.HELP ...

  7. Obstetrical Pain-relieving Drugs as Predictors of Infant Behavior Variability

    ERIC Educational Resources Information Center

    Aleksandrowicz, Malca K.; Aleksandrowicz, Dov R.

    1974-01-01

    A study of the relationship between pain-relieving drugs given to mothers during labor and delivery and neonatal behavior as assessed by the Brazelton Scales. Tested 44 infants on eight different days during their first month of life. (SDH)

  8. Usefulness of T2*-weighted MRI in the detection of adnexal torsion

    PubMed Central

    Kawai, Nobuyuki; Kanematsu, Masayuki; Kawaguchi, Shimpei; Kojima, Toshihisa; Furui, Tatsuro; Morishige, Ken-ichirou; Matsuo, Masayuki

    2016-01-01

    Background The usefulness of T2*-weighted (T2*W) imaging for the detection of adnexal torsion has yet to be determined. Purpose To assess the usefulness of T2*W imaging for detecting and differentiating adnexal torsion. Material and Methods Eight patients with eight ovaries with torsion and 44 patients with 72 ovaries without torsion were included in this study. All patients underwent 1.5-T magnetic resonance imaging (MRI) including T2*W images. The frequency and distribution of hypointensity on T2*W images were compared between ovaries with torsion and ovaries without torsion. Results Hypointensity on T2*W images was significantly more frequent in ovaries with torsion than in ovaries without torsion (75% vs. 36%; P < 0.05). Among patients with hypointensity on T2*W images, the frequency of diffuse hypointensity was significantly higher in ovaries with torsion than in ovaries without torsion (83% vs. 0%; P < 0.01); whereas the frequency of focal hypointensity was significantly lower in ovaries with torsion than in ovaries without torsion (17% vs. 100%; P < 0.01). Conclusion The presence and distribution of hypointensity on T2*W images may play a supplementary role in the detection of adnexal torsion. PMID:27478621

  9. Method of forming a stress relieved amorphous tetrahedrally-coordinated carbon film

    DOEpatents

    Friedmann, Thomas A.; Sullivan, John P.

    2000-01-01

    A stress-relieved amorphous-diamond film is formed by depositing an amorphous diamond film with specific atomic structure and bonding on to a substrate, and annealing the film at sufficiently high temperature to relieve the compressive stress in said film without significantly softening said film. The maximum annealing temperature is preferably on the order of 650.degree. C., a much lower value than is expected from the annealing behavior of other materials.

  10. DNA structure and function.

    PubMed

    Travers, Andrew; Muskhelishvili, Georgi

    2015-06-01

    The proposal of a double-helical structure for DNA over 60 years ago provided an eminently satisfying explanation for the heritability of genetic information. But why is DNA, and not RNA, now the dominant biological information store? We argue that, in addition to its coding function, the ability of DNA, unlike RNA, to adopt a B-DNA structure confers advantages both for information accessibility and for packaging. The information encoded by DNA is both digital - the precise base specifying, for example, amino acid sequences - and analogue. The latter determines the sequence-dependent physicochemical properties of DNA, for example, its stiffness and susceptibility to strand separation. Most importantly, DNA chirality enables the formation of supercoiling under torsional stress. We review recent evidence suggesting that DNA supercoiling, particularly that generated by DNA translocases, is a major driver of gene regulation and patterns of chromosomal gene organization, and in its guise as a promoter of DNA packaging enables DNA to act as an energy store to facilitate the passage of translocating enzymes such as RNA polymerase.

  11. Chromatin Fiber Dynamics under Tension and Torsion

    PubMed Central

    Lavelle, Christophe; Victor, Jean-Marc; Zlatanova, Jordanka

    2010-01-01

    Genetic and epigenetic information in eukaryotic cells is carried on chromosomes, basically consisting of large compact supercoiled chromatin fibers. Micromanipulations have recently led to great advances in the knowledge of the complex mechanisms underlying the regulation of DNA transaction events by nucleosome and chromatin structural changes. Indeed, magnetic and optical tweezers have allowed opportunities to handle single nucleosomal particles or nucleosomal arrays and measure their response to forces and torques, mimicking the molecular constraints imposed in vivo by various molecular motors acting on the DNA. These challenging technical approaches provide us with deeper understanding of the way chromatin dynamically packages our genome and participates in the regulation of cellular metabolism. PMID:20480035

  12. Fault diagnosis of planetary gearboxes via torsional vibration signal analysis

    NASA Astrophysics Data System (ADS)

    Feng, Zhipeng; Zuo, Ming J.

    2013-04-01

    Torsional vibration signals are theoretically free from the amplitude modulation effect caused by time variant vibration transfer paths due to the rotation of planet carrier and sun gear, and therefore their spectral structure are simpler than transverse vibration signals. Thus, it is potentially easy and effective to diagnose planetary gearbox faults via torsional vibration signal analysis. We give explicit equations to model torsional vibration signals, considering both distributed gear faults (like manufacturing or assembly errors) and local gear faults (like pitting, crack or breakage of one tooth), and derive the characteristics of both the traditional Fourier spectrum and the proposed demodulated spectra of amplitude envelope and instantaneous frequency. These derivations are not only effective to diagnose single gear fault of planetary gearboxes, but can also be generalized to detect and locate multiple gear faults. We validate experimentally the signal models, as well as the Fourier spectral analysis and demodulation analysis methods.

  13. Torsion Strain Effects on Critical Currents of Hts Superconducting Tapes

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  14. Complete axial torsion of pregnant uterus with leiomyoma

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Terrano, William

    2017-01-01

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

  17. BCN nanotubes as highly sensitive torsional electromechanical transducers.

    PubMed

    Garel, Jonathan; Zhao, Chong; Popovitz-Biro, Ronit; Golberg, Dmitri; Wang, Wenlong; Joselevich, Ernesto

    2014-11-12

    Owing to their mechanically tunable electronic properties, carbon nanotubes (CNTs) have been widely studied as potential components for nanoelectromechanical systems (NEMS); however, the mechanical properties of multiwall CNTs are often limited by the weak shear interactions between the graphitic layers. Boron nitride nanotubes (BNNTs) exhibit a strong interlayer mechanical coupling, but their high electrical resistance limits their use as electromechanical transducers. Can the outstanding mechanical properties of BNNTs be combined with the electromechanical properties of CNTs in one hybrid structure? Here, we report the first experimental study of boron carbonitride nanotube (BCNNT) mechanics and electromechanics. We found that the hybrid BCNNTs are up to five times torsionally stiffer and stronger than CNTs, thereby retaining to a large extent the ultrahigh torsional stiffness of BNNTs. At the same time, we show that the electrical response of BCNNTs to torsion is 1 to 2 orders of magnitude higher than that of CNTs. These results demonstrate that BCNNTs could be especially attractive building blocks for NEMS.

  18. Determining Angle of Humeral Torsion Using Image Software Technique

    PubMed Central

    Sethi, Madhu; Vasudeva, Neelam

    2016-01-01

    Introduction Several researches have been done on the measurement of angles of humeral torsion in different parts of the world. Previously described methods were more complicated, not much accurate, cumbersome or required sophisticated instruments. Aim The present study was conducted with the aim to determine the angles of humeral torsion with a newer simple technique using digital images and image tool software. Materials and Methods A total of 250 dry normal adult human humeri were obtained from the bone bank of Department of Anatomy. The length and mid-shaft circumference of each bone was measured with the help of measuring tape. The angle of humeral torsion was measured directly from the digital images by the image analysis using Image Tool 3.0 software program. The data was analysed statistically with SPSS version 17 using unpaired t-test and Spearman’s rank order correlation coefficient. Results The mean angle of torsion was 64.57°±7.56°. On the right side it was 66.84°±9.69°, whereas, on the left side it was found to be 63.31±9.50°. The mean humeral length was 31.6 cm on right side and 30.33 cm on left side. Mid shaft circumference was 5.79 on right side and 5.63 cm on left side. No statistical differences were seen in angles between right and left humeri (p>0.001). Conclusion From our study, it was concluded that circumference of shaft is inversely proportional to angle of humeral torsion. The length and side of humerus has no relation with the humeral torsion. With advancement of digital technology, it is better to use new image softwares for anatomical studies. PMID:27891326

  19. Impact of torsion and stretching on the thermal conductivity of polyethylene strands

    NASA Astrophysics Data System (ADS)

    Tu, Runchun; Liao, Quanwen; Zeng, Lingping; Liu, Zhichun; Liu, Wei

    2017-03-01

    A single polyethylene chain was reported to have a high metal-like thermal conductivity (TC), which stands in sharp contrast to the thermally insulating feature of common bulk polyethylene materials. This work numerically investigates the impact of torsion and stretching on the TC of polyethylene strands by using equilibrium molecular dynamics simulations. The simulation results show that torsion slightly reduces the TC of a single polyethylene chain. In contrast, the heat conduction of polyethylene strands could be slightly enhanced under torsional loading with a specific torsional angle. Particularly, an apparent improvement of TC of polyethylene strands is achieved by combining torsion and stretching functions. It is found that the TC of torsional polyethylene strands is sensitive to torsional patterns. Our study proposes a specific torsional pattern of polyethylene strands that significantly enhances the heat conduction of the original counterpart. This study will play an essential role in guiding the improvements of thermal conduction property of polymers.

  20. Missed torsion in undescended testes detected by scintigraphy: testicular scintigraphy a decisive complementary tool.

    PubMed

    Kodali, Sunil Kumar; Abdullah, Zuhair Saleh; Sharma, Punit; Khan, Muhammad Umar; Naeem, Muhammad

    2013-01-01

    Torsion of undescended testis, although not uncommon, causes diagnostic difficulties. We here present testicular scintigraphy images of a typical case of torsion of an undescended inguinal testis with disparity between clinical and ultrasonography (USG) findings in the contralateral retractile testis.

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

    NASA Astrophysics Data System (ADS)

    Arioli, Gianni; Gazzola, Filippo

    2017-01-01

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

  2. Massless fermions and Kaluza--Klein theory with torsion

    SciTech Connect

    Wu, Y.; Zee, A.

    1984-09-01

    A pure Kaluza--Klein theory contains no massless fermion in four-dimensional theory. We investigate the effect of introducing torsion on the internal manifold and find that there are massless fermions. The hope is that given an isometry group the representation to which these fermions belong is fixed, in contrast to the situation in Yang--Mills theory. We show that this is indeed the case, but the representations do not appear to be the ones favored by current theoretical prejudice. The cases with parallelizable torsions on a group manifold as the internal manifold are analyzed in detail.

  3. New supersymmetric index of heterotic compactifications with torsion

    NASA Astrophysics Data System (ADS)

    Israël, Dan; Sarkis, Matthieu

    2015-12-01

    We compute the new supersymmetric index of a large class of N=2 heterotic compactifications with torsion, corresponding to principal two-torus bundles over warped K3 surfaces with H-flux. Starting from a UV description as a (0,2) gauged linear sigma-model with torsion, we use supersymmetric localization techniques to provide an explicit expression of the index as a sum over the Jeffrey-Kirwan residues of the one-loop determinant. We finally propose a geometrical formula that gives the new supersymmetric index in terms of bundle data, regardless of any particular choice of underlying two-dimensional theory.

  4. Coated Fused Silica Fibers for Enhanced Sensitivity Torsion Pendulum

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Horowitz, Jordan; Camp, Jordan

    2007-01-01

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

  5. Free torsional vibrations of tapered cantilever I-beams

    NASA Astrophysics Data System (ADS)

    Rao, C. Kameswara; Mirza, S.

    1988-08-01

    Torsional vibration characteristics of linearly tapered cantilever I-beams have been studied by using the Galerkin finite element method. A third degree polynomial is assumed for the angle of twist. The analysis presented is valid for long beams and includes the effect of warping. The individual as well as combined effects of linear tapers in the width of the flanges and the depth of the web on the torsional vibration of cantilever I-beams are investigated. Numerical results generated for various values of taper ratios are presented in graphical form.

  6. Portal venous thrombosis developing after torsion of a wandering spleen.

    PubMed

    Yilmaz, Ö; Kiziltan, R; Almali, N; Aras, A

    2017-03-01

    Torsion of a wandering spleen is a rare disease. The symptoms and signs of this condition are only present when the splenic pedicle torts. The etiological factors are the congenital absence of the ligaments that hold the spleen in its normal anatomic position, or the relaxation of these ligaments resulting from conditions like trauma and abdominal surgery. We aimed to present a rare case with torsion of wandering spleen that consequently developed thrombosis of portal vein and its branches, taking into consideration the relevant literature.

  7. Wandering spleen with chronic torsion in a patient with thalassaemia.

    PubMed

    Ho, Chi Long

    2014-12-01

    Wandering spleen or splenoptosis is an uncommon entity and often an asymptomatic finding of acute abdomen in the emergency department. A high index of suspicion for splenic torsion is required, particularly in patients with known splenomegaly, as this condition could potentially lead to splenic infarction. Recognition of this condition can help avoid potential confusion with acute abdomen of other aetiologies. Herein, we present a unique case of wandering spleen with chronic torsion, which, to the best of our knowledge, has never been described in an elderly patient with haemoglobin H thalassaemia. We also review the literature for the aetiology and pathogenesis of wandering spleen, and discuss the relevant diagnostic modalities and treatment options.

  8. A monolithically integrated torsional CMOS-MEMS relay

    NASA Astrophysics Data System (ADS)

    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.

  9. Torsion of a neoplastic intrascrotal testis: when the torsion reveals the mass. A case report and review.

    PubMed

    Albino, Giuseppe; Nenna, Rosanna; Corvasce, Antonio; Marucco, Ettore Cirillo

    2012-12-01

    Cases of torsion of the spermatic cord are rare in men over 30-years-old. Testicular tumors manifest themselves rarely with symptoms of acute scrotum. We report the case of a 38-years-old patient who presented for a suspected left testis torsion. On examination, the testicle was markedly increased in size and painful. The manual derotation made pain dramatically disappear. He came to our attention after about a month asking for an orchidopexy. During the surgery a biopsy was performed. The diagnosis was a Yolk Sac Tumor. A radical inguinal orchiectomy was performed with left hemiscrotal excision, "in block". He performed four cycles of chemotherapy and with no recurrence after 12 months of follow-up. In literature only seven cases of torsion of an intrascrotal testicle with cancer are reported. Our case is the eighth one.

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

    PubMed

    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.

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

    SciTech Connect

    Fedoruk, Sergey Ivanov, Evgeny; Smilga, Andrei

    2014-05-15

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

  12. Long-wavelength torsional modes of solar coronal plasma structures

    NASA Astrophysics Data System (ADS)

    Vasheghani Farahani, S.; Nakariakov, V. M.; van Doorsselaere, T.

    2010-07-01

    Aims: We consider the effects of the magnetic twist and plasma rotation on the propagation of torsional m = 0 perturbations of cylindrical plasma structures (straight magnetic flux tubes) in the case when the wavelength is much longer than the cylinder diameter. Methods: The second order thin flux tube approximation is used to derive dispersion relations and phase relations in linear long-wavelength axisymmetric magnetohydrodynamic waves in uniformly twisted and rotating plasma structures. Results: Asymptotic dispersion relations linking phase speeds with the plasma parameters are derived. When twist and rotation are both present, the phase speed of torsional waves depends upon the direction of the wave propagation, and also the waves are compressible. The phase relations show that in a torsional wave the density and azimuthal magnetic field perturbations are in phase with the axial magnetic field perturbations and anti-phase with tube cross-section perturbations. In a zero-β non-rotating plasma cylinder confined by the equilibrium twist, the density perturbation is found to be about 66 percent of the amplitude of the twist perturbation in torsional waves.

  13. Torsional Oscillations and Waves Projected on the Wall

    ERIC Educational Resources Information Center

    Bartlett, Albert A.

    2008-01-01

    The article "Torsional Oscillations with Lorentz Force" by Paul Gluck provides a glimpse into the major world of ancient physics demonstrations in the late 19th and first half of the 20th centuries. The apparatus that was described and similar pieces of apparatus are the basis for many memorable but long forgotten educational demonstrations. The…

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

    PubMed Central

    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

  15. Toeplitz Operators, Analytic Torsion, and the Hypoelliptic Laplacian

    NASA Astrophysics Data System (ADS)

    Bismut, Jean-Michel

    2016-12-01

    The purpose of this paper is to explain how Toeplitz operators can be used in studying asymptotic torsion, and also in the theory of the hypoelliptic Laplacian. The role of the hypoelliptic Laplacian in the explicit computation of orbital integrals will be described. The geodesic flow will be viewed as implementing a dynamical version of Fourier transform.

  16. Solution of elastoplastic torsion problem by boundary integral method

    NASA Technical Reports Server (NTRS)

    Mendelson, A.

    1975-01-01

    The boundary integral method was applied to the elastoplastic analysis of the torsion of prismatic bars, and the results are compared with those obtained by the finite difference method. Although fewer unknowns were used, very good accuracy was obtained with the boundary integral method. Both simply and multiply connected bodies can be handled with equal ease.

  17. New Approaches to Data Acquisitions in a Torsion Pendulum Experiment

    ERIC Educational Resources Information Center

    Jiang, Daya; Xiao, Jinghua; Li, Haihong; Dai, Qionglin

    2007-01-01

    In this paper, two simple non-contact and cost-effective methods to acquire data in the student laboratory are applied to investigate the motion of a torsion pendulum. The first method is based on a Hall sensor, while the second makes use of an optical mouse.

  18. Quaternionic Torsion Geometry, Superconformal Symmetry and T-duality

    SciTech Connect

    Swann, Andrew

    2009-02-02

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

  19. A measurement of G with a cryogenic torsion pendulum.

    PubMed

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

    2014-10-13

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

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

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

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

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

    PubMed

    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.

  2. Protective role of erythropoietin during testicular torsion of the rats.

    PubMed

    Yazihan, Nuray; Ataoglu, Haluk; Koku, Naim; Erdemli, Esra; Sargin, Ayse Kose

    2007-10-01

    Testicular torsion is an important clinical urgency. Similar mechanisms occurred after detorsion of the affected testis as in the ischemia reperfusion (I/R) damage. This study was designed to investigate the effects of erythropoietin (EPO) treatment after unilateral testicular torsion. Fifty male Sprague-Dawley rats were divided into five groups. Group 1 underwent a sham operation of the right testis under general anesthesia. Group 2 was same as sham, and EPO (3,000 IU/kg) infused i.p., group 3 underwent a similar operation but the right testis was rotated 720 degrees clockwise for 1 h, maintained by fixing the testis to the scrotum, and saline infused during the procedure. Group 4 underwent similar torsion but EPO was infused half an hour before the detorsion procedure, and in group 5, EPO was infused after detorsion procedure. Four hours after detorsion, ipsilateral and contralateral testes were taken out for evaluation. Treatment with EPO improved testicular structures in the ipsilateral testis but improvement was less in the contralateral testis histologically, but EPO treatment decreased germ cell apoptosis in both testes following testicular IR. TNF-alpha, IL-1beta, IL-6 and nitrite levels decreased after EPO treatment especially in the ipsilateral testis. We conclude that testicular I/R causes an increase in germ cell apoptosis both in the ipsilateral and contralateral testes. Erythropoietin has antiapoptotic and anti-inflammatory effects following testicular torsion.

  3. Contralateral genitofemoral sympathetic nerve discharge increases following ipsilateral testicular torsion.

    PubMed

    Otçu, Selçuk; Durakoğugil, Murat; Orer, Hakan S; Tanyel, Feridun C

    2002-10-01

    The decrease in blood flow due to the activation of sympathetic system has been suggested to play a role in contralateral testicular deterioration associated with unilateral testicular torsion. Sympathetic nerve discharges (SND) from the genitofemoral nerve were evaluated before and during unilateral testicular torsion. Under urethane anesthesia, arterial blood pressure and SND from splanchnic and right genitofemoral nerves were recorded in 12 male Sprague-Dawley rats, 8 of which were included in subsequent analyses. After control recordings of basal discharges for 2 min the left testis was twisted 720 degrees counterclockwise, and recording was resumed for an additional 30 min. Changes in nerve activity were calculated by measuring the area under the autospectrum curve, and alterations were compared. Following testicular torsion no significant changes were obtained for splanchnic SND, but the amplitude of SND from contralateral genitofemoral nerve showed an overall increase of 21.20+/-7.03% in six rats. This increase lasted about 10-15 min and activities returned to pretorsion levels. In two other rats no significant change was observed in either splanchnic or genitofemoral SND. Ipsilateral testicular torsion results in a transient increase in genitofemoral SND. A possible autonomic reflex mechanism may exist, and it may be activated by noxious stimuli from contralateral side. This reflex mechanism may initiate a series of events that lead to the injury of contralateral testis.

  4. Development of Torsional and Linear Piezoelectrically Driven Motors

    NASA Technical Reports Server (NTRS)

    Duong, Khanh; Newton, David; Garcia, Ephrahim

    1996-01-01

    The development of rotary and linear inchworm-motors using piezoelectric actuators is presented. The motors' design has the advantage of a macro and micro stepper motor with high load and speed. The torsional design is capable of fast angular positioning with micro level accuracy. Additionally, the rotary motor, as designed, can be used as a clutch/brake mechanism. Constructed prototype motors of both types along with their characteristics are presented. The torsional motor consists of a torsional section that provides angular displacement and torque, and two alternating clamping sections which provide the holding force. The motor relies on the principal piezoelectric coupling coefficient (d33) with no torsional elements, increasing its torque capability. The linear motor consists of a longitudinal vibrator that provides displacement and load, and two alternating clamping sections which provide the holding force. This design eliminates bending moment, tension and shear applied to the actuator elements, increase its load capability and life. Innovative flexure designs have been introduced for both motor types. Critical issues that affect the design and performance of the motors are explored and discussed. Experiments are performed demonstrating the motor prototypes based on the aforementioned design considerations.

  5. The Rotation-Torsion Spectrum of CH_2DOH

    NASA Astrophysics Data System (ADS)

    Hilali, A. El; Coudert, L. H.; Margulès, L.; Motiyenko, R.; Klee, S.

    2010-06-01

    Due to the asymmetry of the CH_2D group, the internal rotation problem in the partially deuterated species of methanol CH_2DOH is a complicated one as, unlike in the normal species CH_3OH, the inertia tensor depends on the angle of internal rotation. The CH_2DOH species also displays a dense far infrared torsional spectrum difficult to assign. Recently 38 torsional subbands of CH_2DOH have been identified, but for most of them there is neither an assignment nor an analysis of their rotational structure. In this paper an analysis of the rotation-torsion spectrum of CH_2DOH will be presented. The rotational structure of 23 torsional subbands have been assigned. These subbands are Δ v_t &ge 1 perpendicular subbands with a value of v'_t up to 10b and values of K' and K'' ranging from 0 to 9. For all subbands, the Q-branch was assigned, for 3 subbands, the R- and P-branches could also be found. The results of the rotational analysis with an expansion in J(J+1) of the new subbands and of already observed ones will be presented. When available, microwave lines within the lower torsional level, recorded in this work or already measured, were added to the data set. A theoretical approach aimed at calculating the rotation-torsion energy levels has also been developed. It is based on an expansion in terms of rotation-torsion operators with C_s symmetry and accounts for the dependence of the inertia tensor on the angle of internal rotation. This approach will be used to carry out a preliminary global analyses of the wavenumbers and of the frequencies. Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spec. 256 (2009) 204. Quade, Liu, Mukhopadhyay, and Su, J. Mol. Spec. 192 (1998) 378; Mukhopadhyay, J. Mol. Struct. 695-696 (2004) 357. Liu and Quade, J. Mol. Spec. 146 (1991) 252 Mukhopadhyay et al., J. Chem. Phys. 116 (2002) 3710.

  6. Torsional waves operating in geodynamo and magnetoconvection simulations

    NASA Astrophysics Data System (ADS)

    Teed, Robert; Jones, Chris; Tobias, Steve

    2015-04-01

    Torsional waves are a principal feature of the dynamics of the fluid outer core where the Earth's magnetic field is generated. These oscillations are Alfvén waves operating about an equilibrium known as a Taylor state (Taylor, 1963) and they propagate in the cylindrical radial direction. The change in core angular momentum inferred from geomagnetic observations has a measurable impact on the length of the day, and the small decadal variations in the length-of-day signal confirm the existence of torsional oscillations (Holme & de Viron, 2013). Many questions remain unanswered about the exact nature of these waves and this presentation will attempt to address some of these. In order to gain insight we perform three-dimensional spherical dynamo and magnetoconvection simulations in parameter regimes where Earth-like magnetic fields are produced. Many of our simulations produce the desired torsional oscillations, identified by their movement at the correct Alfvén speed, and several show Earth-like core travel times of around 4 years. Our dynamo simulations (Teed et al., 2014) show torsional waves within the tangent cylinder region that also have the ability to pass through this theoretical cylinder. By calculating the driving terms for these waves we find that both the Reynolds force and ageostrophic convection acting through the Lorentz force can be important in driving torsional oscillations. Driven by a desire to reach smaller Ekman numbers and larger magnetic field strengths, which are computationally unattainable in dynamo simulations, we perform, in our follow up work, magnetoconvection simulations (Teed et al., 2015) by imposing a dipolar field on the core-mantle boundary. Under this configuration we find a transition, at low Ekman numbers, to regimes where excitation is found only at the tangent cylinder, is delivered by the Lorentz force and gives rise to a periodic Earth-like wave pattern. This pattern is approximately operating on a 4 to 5 year timescale

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

    PubMed

    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 < 0.05). Erdosteine treatment ameliorated lipid peroxidation after torsion/detorsion in ipsilateral testis (p < 0.05). Also, xanthine oxidase activity of ipsilateral testis was increased in torsion/detorsion group in comparison with the others (p < 0.05). Nitric oxide (NO) level of ipsilateral testis was higher in all experimental groups than sham operated control group (p < 0.05). Also, NO level of torsion group was increased in comparison with detorsion groups (p < 0.05). 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 < 0.05). Superoxide dismutase activity of ipsilateral testis was higher in torsion/detorsion and torsion/detorsion+erdosteine groups than control and torsion groups (p < 0

  8. The torsional mechanical properties of copper nanowires supported by carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Huan, Hao; Fu, Bing; Ye, Xiang

    2017-02-01

    The torsional mechanical properties of hollow Cu nanowires supported by carbon nanotubes (CNTs) are studied by all atoms molecular dynamic simulation. It is found that the critical angles of Cu nanowires almost do not decrease when the temperature increases to a limit value, and this invariant feature also has been found as the torsional loading rate is lower than 4.5 ×1012 °s-1. Due to the support of CNTs, Cu nanowires can bear larger torsional angle at low torsional rates and high temperatures compared with those without CNTs, which means the CNTs will increase the torsion-tolerance of Cu nanowires.

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

    PubMed

    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.

  10. Torsion Bounds from CP Violation α2-DYNAMO in Axion-Photon Cosmic Plasma

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    Years ago Mohanty and Sarkar [Phys. Lett. B 433, 424 (1998)] have placed bounds on torsion mass from K meson physics. In this paper, associating torsion to axions a la Campanelli et al. [Phys. Rev. D 72, 123001 (2005)], it is shown that it is possible to place limits on spacetime torsion by considering an efficient α2-dynamo CP violation term. Therefore instead of Kostelecky et al. [Phys. Rev. Lett. 100, 111102 (2008)] torsion bounds from Lorentz violation, here torsion bounds are obtained from CP violation through dynamo magnetic field amplification. It is also shown that oscillating photon-axion frequency peak is reduced to 10-7 Hz due to torsion mass (or Planck mass when torsion does not propagate) contribution to the photon-axion-torsion action. Though torsion does not couple to electromagnetic fields at classical level, it does at the quantum level. Recently, Garcia de Andrade [Phys. Lett. B 468, 28 (2011)] has shown that the photon sector of Lorentz violation (LV) Lagrangian leads to linear nonstandard Maxwell equations where the magnetic field decays slower giving rise to a seed for galactic dynamos. Torsion constraints of the order of K0≈10-42 GeV can be obtained which are more stringent than the value obtained by Kostelecky et al. A lower bound for the existence of galactic dynamos is obtained for torsion as K0≈10-37 GeV.

  11. [Theory analysis and clinical application of spirit-regulating and pain-relieving acupuncture method].

    PubMed

    Chen, Liang; Tang, Lewei; Du, Huaibin; Zheng, Hui; Liang, Fanrong

    2015-04-01

    The theoretical foundation and scientific connotation of spirit-regulating and pain-relieving acupuncture method as well as its clinical application for pain are discussed. During spirit regulation, attention should be paid on regulating heart and brain, while acupoints should be selected mainly from the Heart Meridian, Pericardium Meridian and Governor Vessel. It has significant efficacy for refractory pain in clinical treatment. Spirit-regulating and pain-relieving acupuncture method is development of acupuncture treating spirit, and it is an important method for pain in clinic. Improvement on sensitization of pain center and brain function is considered as one of the mechanisms in spirit-regulating and pain-relieving acupuncture method.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Novel technique for relieving anastomotic tension using halo-vest immobilization after tracheal sleeve resection.

    PubMed

    Imai, Kazuhiro; Minamiya, Yoshihiro; Saito, Hajime; Miyakoshi, Naohisa; Hongo, Michio; Kasukawa, Yuji; Ishikawa, Yoshinori; Motoyama, Satoru; Sato, Yusuke; Shimada, Yoichi; Ogawa, Jun-ichi

    2013-07-01

    We describe a novel technique of using halo-vest-enforced immobilization to relieve anastomotic tension after tracheal sleeve resection. Immediately after the tracheal sleeve resection, four halo titanium pins were inserted in the skulls of the patients to secure the halo-vest. All patients fitted with halo-vests were able to eat and drink and their clinical course was good. Bronchoscopy confirmed the absence of anastomotic leaks and stenoses, and there were no complications associated with the halo-vest. We believe that ensuring neck flexion using a halo-vest after tracheal sleeve resection is an excellent way of relieving anastomotic tension that would predispose the wound to dehiscence.

  14. DNA-DNA interaction beyond the ground state

    NASA Astrophysics Data System (ADS)

    Lee, D. J.; Wynveen, A.; Kornyshev, A. A.

    2004-11-01

    The electrostatic interaction potential between DNA duplexes in solution is a basis for the statistical mechanics of columnar DNA assemblies. It may also play an important role in recombination of homologous genes. We develop a theory of this interaction that includes thermal torsional fluctuations of DNA using field-theoretical methods and Monte Carlo simulations. The theory extends and rationalizes the earlier suggested variational approach which was developed in the context of a ground state theory of interaction of nonhomologous duplexes. It shows that the heuristic variational theory is equivalent to the Hartree self-consistent field approximation. By comparison of the Hartree approximation with an exact solution based on the QM analogy of path integrals, as well as Monte Carlo simulations, we show that this easily analytically-tractable approximation works very well in most cases. Thermal fluctuations do not remove the ability of DNA molecules to attract each other at favorable azimuthal conformations, neither do they wash out the possibility of electrostatic “snap-shot” recognition of homologous sequences, considered earlier on the basis of ground state calculations. At short distances DNA molecules undergo a “torsional alignment transition,” which is first order for nonhomologous DNA and weaker order for homologous sequences.

  15. DNA-DNA interaction beyond the ground state.

    PubMed

    Lee, D J; Wynveen, A; Kornyshev, A A

    2004-11-01

    The electrostatic interaction potential between DNA duplexes in solution is a basis for the statistical mechanics of columnar DNA assemblies. It may also play an important role in recombination of homologous genes. We develop a theory of this interaction that includes thermal torsional fluctuations of DNA using field-theoretical methods and Monte Carlo simulations. The theory extends and rationalizes the earlier suggested variational approach which was developed in the context of a ground state theory of interaction of nonhomologous duplexes. It shows that the heuristic variational theory is equivalent to the Hartree self-consistent field approximation. By comparison of the Hartree approximation with an exact solution based on the QM analogy of path integrals, as well as Monte Carlo simulations, we show that this easily analytically-tractable approximation works very well in most cases. Thermal fluctuations do not remove the ability of DNA molecules to attract each other at favorable azimuthal conformations, neither do they wash out the possibility of electrostatic "snap-shot" recognition of homologous sequences, considered earlier on the basis of ground state calculations. At short distances DNA molecules undergo a "torsional alignment transition," which is first order for nonhomologous DNA and weaker order for homologous sequences.

  16. Behavior of supercoiled DNA.

    PubMed Central

    Strick, T R; Allemand, J F; Bensimon, D; Croquette, V

    1998-01-01

    We study DNA supercoiling in a quantitative fashion by micromanipulating single linear DNA molecules with a magnetic field gradient. By anchoring one end of the DNA to multiple sites on a magnetic bead and the other end to multiple sites on a glass surface, we were able to exert torsional control on the DNA. A rotating magnetic field was used to induce rotation of the magnetic bead, and reversibly over- and underwind the molecule. The magnetic field was also used to increase or decrease the stretching force exerted by the magnetic bead on the DNA. The molecule's degree of supercoiling could therefore be quantitatively controlled and monitored, and tethered-particle motion analysis allowed us to measure the stretching force acting on the DNA. Experimental results indicate that this is a very powerful technique for measuring forces at the picoscale. We studied the effect of stretching forces ranging from 0.01 pN to 100 pN on supercoiled DNA (-0.1 < sigma < 0.2) in a variety of ionic conditions. Other effects, such as stretching-relaxing hysteresis and the braiding of two DNA molecules, are discussed. PMID:9545060

  17. Volar denervation and osteophyte resection to relieve volar CMC joint pain

    PubMed Central

    Dellon, A. Lee

    2017-01-01

    Abstract At mean 125.6 months, pain was reduced from mean of 8.7 to 0.67, p < .001. Each of three patients, two of whom were musicians, returned to full professional ability. It is concluded that volar CMC joint denervation is a useful procedure, preserving joint function and relieving pain long-term. PMID:28243611

  18. 21 CFR 868.5115 - Device to relieve acute upper airway obstruction.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Device to relieve acute upper airway obstruction. 868.5115 Section 868.5115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5115 Device...

  19. Korean Emotional Laborers' Job Stressors and Relievers: Focus on Work Conditions and Emotional Labor Properties

    PubMed Central

    Lee, Garam

    2015-01-01

    Background The present study aims to investigate job stressors and stress relievers for Korean emotional laborers, specifically focusing on the effects of work conditions and emotional labor properties. Emotional laborers are asked to hide or distort their real emotions in their interaction with clients. They are exposed to high levels of stress in the emotional labor process, which leads to serious mental health risks including burnout, depression, and even suicide impulse. Exploring job stressors and relieving factors would be the first step in seeking alternatives to protect emotional laborers from those mental health risks. Methods Using the third wave data of Korean Working Conditions Survey, logistic regression analysis was conducted for two purposes: to examine the relations of emotional labor and stress, and to find out job stressors and relievers for emotional laborers. Results The chances of stress arousal are 3.5 times higher for emotional laborers; emotional laborers experience double risk-burden for stress arousal. In addition to general job stressors, emotional laborers need to bear burdens related to emotional labor properties. The effect of social support at the workplace is not significant for stress relief, unlike common assumptions, whereas subjective satisfaction (wage satisfaction and work-life balance) is proven to have relieving effects on emotional laborers' job stress. Conclusion From the results, the importance of a balanced understanding of emotional labor for establishing effective policies for emotional laborer protection is stressed. PMID:26929847

  20. UV photolysis for relieved inhibition of sulfadiazine (SD) to biomass growth.

    PubMed

    Pan, Shihui; Yan, Ning; Zhang, Yongming; Rittmann, Bruce E

    2015-05-01

    UV photolysis was used to relieve inhibition of biomass growth by sulfadiazine (SD), a broad-spectrum anti-microbial. To investigate the effects of SD on biomass growth, three substrates-glucose alone (G), glucose plus sulfadiazine (G+SD), and glucose plus photolyzed SD (G+PSD)-were used to culture the bacteria acclimated to glucose. The biomass was strongly inhibited when SD was added into the glucose solution, but inhibition was relieved to a significant degree when the SD was treated with UV irradiation as a pretreatment. The biomass growth kinetics were described well by the Monod model when glucose was used as a substrate alone, but the kinetics followed a hybrid Aiba model for non-competitive inhibition when SD was added to the solution. When photolyzed SD was added to glucose solution to replace original SD, the growth still followed Aiba inhibition, but inhibition was significantly relieved: the maximum specific growth rate (μ max) increased by 17 %, and the Aiba inhibition concentration increased by 60 %. Aniline, a major product of UV photolysis, supported the growth of the glucose-biodegrading bacteria. Thus, UV photolysis of SD significantly relieved inhibition by lowering the SD concentration and by generating a biodegradable product.

  1. Nitrous oxide by itself is insufficient to relieve pain due to castration in piglet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surgical castration is performed on all male pigs in the United States. However, castration is painful and analgesics have been considered to relieve pain. Inhalant gases with analgesic properties allow for a fast induction, short-term and reversible effects, and are a needle-free option. Nitrous ox...

  2. Prescription Pain Reliever Abuse and Dependence among Adolescents: A Nationally Representative Study

    ERIC Educational Resources Information Center

    Wu, Li-Tzy; Ringwalt, Christopher L.; Mannelli, Paolo; Patkar, Ashwin A.

    2008-01-01

    The study investigates the prevalence, patterns, and correlates of adolescents' abuse, sub-threshold dependence, and dependence on prescription pain relievers (PPRs) in a nationally representative sample. Results show dependence on PPRs can take place without abuse and that sub-threshold dependence could have implications for major diagnostic…

  3. The Torsion of Members Having Sections Common in Aircraft Construction

    NASA Technical Reports Server (NTRS)

    Trayer, George W; March, H W

    1930-01-01

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

  4. MAGNETOSEISMOLOGY: EIGENMODES OF TORSIONAL ALFVEN WAVES IN STRATIFIED SOLAR WAVEGUIDES

    SciTech Connect

    Verth, G.; Goossens, M.; Erdelyi, R. E-mail: Marcel.Goossens@wis.kuleuven.b

    2010-05-10

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

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

    PubMed

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

    2014-03-01

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

  6. Bending and Torsion Load Alleviator With Automatic Reset

    NASA Technical Reports Server (NTRS)

    delaFuente, Horacio M. (Inventor); Eubanks, Michael C. (Inventor); Dao, Anthony X. (Inventor)

    1996-01-01

    A force transmitting load alleviator apparatus and method are provided for rotatably and pivotally driving a member to be protected against overload torsional and bending (moment) forces. The load alleviator includes at least one bias spring to resiliently bias cam followers and cam surfaces together and to maintain them in locked engagement unless a predetermined load is exceeded whereupon a center housing is pivotal or rotational with respect to a crown assembly. This pivotal and rotational movement results in frictional dissipation of the overload force by an energy dissipator. The energy dissipator can be provided to dissipate substantially more energy from the overload force than from the bias force that automatically resets the center housing and crown assembly to the normally fixed centered alignment. The torsional and bending (moment) overload levels can designed independently of each other.

  7. Torsional Newton-Cartan geometry from the Noether procedure

    NASA Astrophysics Data System (ADS)

    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.

  8. Torsion of a Wandering Spleen Presenting as Acute Abdomen

    PubMed Central

    Chauhan, Narvir Singh; Kumar, Satish

    2016-01-01

    Summary Background Wandering spleen is a rare condition which if uncorrected, can result in torsion and infarction. Clinical presentation of a wandering spleen can vary from asymptomatic abdominal mass to acute abdominal pain. Radiological investigations play a pivotal role in diagnosis as the clinical diagnosis is usually impossible. Case Report We present a case of wandering spleen with torsion and complete infarction that occurred in a 32-year-old multiparous female. The diagnosis was established preoperatively on colour Doppler and CT of the abdomen with subsequent confirmation on surgery. Conclusions Wandering spleen is a rare clinical condition which can present as acute abdomen. An increased awareness of this entity together with the timely use of ultrasound and CT of the abdomen can play an important role in preoperative diagnosis and surgical management. PMID:27057261

  9. Wandering spleen with chronic torsion in a patient with thalassaemia

    PubMed Central

    Ho, Chi Long

    2014-01-01

    Wandering spleen or splenoptosis is an uncommon entity and often an asymptomatic finding of acute abdomen in the emergency department. A high index of suspicion for splenic torsion is required, particularly in patients with known splenomegaly, as this condition could potentially lead to splenic infarction. Recognition of this condition can help avoid potential confusion with acute abdomen of other aetiologies. Herein, we present a unique case of wandering spleen with chronic torsion, which, to the best of our knowledge, has never been described in an elderly patient with haemoglobin H thalassaemia. We also review the literature for the aetiology and pathogenesis of wandering spleen, and discuss the relevant diagnostic modalities and treatment options. PMID:25630326

  10. Torsion, parity-odd response, and anomalies in topological states

    NASA Astrophysics Data System (ADS)

    Parrikar, Onkar; Hughes, Taylor L.; Leigh, Robert G.

    2014-11-01

    We study the response of a class of topological systems to electromagnetic and gravitational sources, including torsion and curvature. By using the technology of anomaly polynomials, we derive the parity-odd response of a massive Dirac fermion in d =2 +1 and d =4 +1 , which provides a simple model for a topological insulator. We discuss the covariant anomalies of the corresponding edge states, from a Callan-Harvey anomaly inflow, as well as a Hamiltonian spectral flow point of view. We also discuss the applicability of our results to other systems such as Weyl semimetals. Finally, using dimensional reduction from d =4 +1 , we derive the effective action for a d =3 +1 time-reversal invariant topological insulator in the presence of torsion and curvature, and discuss its various physical consequences.

  11. Exact solutions in 3D gravity with torsion

    NASA Astrophysics Data System (ADS)

    González, P. A.; Vásquez, Yerko

    2011-08-01

    We study the three-dimensional gravity with torsion given by the Mielke-Baekler (MB) model coupled to gravitational Chern-Simons term, and that possess electric charge described by Maxwell-Chern-Simons electrodynamics. We find and discuss this theory's charged black holes solutions and uncharged solutions. We find that for vanishing torsion our solutions by means of a coordinate transformation can be written as three-dimensional Chern-Simons black holes. We also discuss a special case of this theory, Topologically Massive Gravity (TMG) at chiral point, and we show that the logarithmic solution of TMG is also a solution of the MB model at a fixed point in the space of parameters. Furthermore, we show that our solutions generalize Gödel type solutions in a particular case. Also, we recover BTZ black hole in Riemann-Cartan spacetime for vanishing charge.

  12. The Ground and First Excited Torsional States of Acetic Acid.

    PubMed

    Ilyushin, V. V.; Alekseev, E. A.; Dyubko, S. F.; Podnos, S. V.; Kleiner, I.; Margulès, L.; Wlodarczak, G.; Demaison, J.; Cosléou, J.; Maté, B.; Karyakin, E. N.; Golubiatnikov, G. Yu.; Fraser, G. T.; Suenram, R. D.; Hougen, J. T.

    2001-02-01

    A global fit of microwave and millimeter-wave rotational transitions in the ground and first excited torsional states (v(t) = 0 and 1) of acetic acid (CH(3)COOH) is reported, which combines older measurements from the literature with new measurements from Kharkov, Lille, and NIST. The fit uses a model developed initially for acetaldehyde and methanol-type internal rotor molecules. It requires 34 parameters to achieve a unitless weighted standard deviation of 0.84 for a total of 2518 data and includes A- and E-species transitions with J torsional interval is available. Copyright 2001 Academic Press.

  13. Modified teleparallel gravity with higher-derivative torsion terms

    NASA Astrophysics Data System (ADS)

    Otalora, Giovanni; Saridakis, Emmanuel N.

    2016-10-01

    We construct F (T ,(∇T) 2,□T ) gravitational modifications, which are novel classes of modified theories arising from higher-derivative torsional terms in the action and are different than their curvature analogue. Applying them in a cosmological framework, we obtain an effective dark energy sector comprised of the novel torsional contributions. We perform a detailed dynamical analysis for two specific examples, extracting the stable late-time solutions and calculating the corresponding observables. We show that the thermal history of the Universe can be reproduced, and it can result in a dark-energy-dominated, accelerating universe, where the dark-energy equation-of-state parameter lies in the quintessence regime, or may exhibit the phantom-divide crossing during the cosmological evolution. Finally, the scale factor behaves asymptotically, either as a power law or as an exponential, in agreement with observations.

  14. Genetic and clinical features of primary torsion dystonia

    PubMed Central

    Ozelius, Laurie J.; Bressman, Susan B.

    2011-01-01

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

  15. Microstructure and texture analyses of polycrystalline ice during hot torsion

    NASA Astrophysics Data System (ADS)

    Journaux, B.; Montagnat, M.; Gest, L.; Barou, F.; Chauve, T.

    2015-12-01

    Water ice Ih is a material with very high plastic anisotropy where deformation is mainly accommodated by dislocation glide on the (0001) plane. This anisotropy gives rise to strong strain incompatibilities between grains during deformation, and therefore impacts texture and microstructure evolution. Accurate understanding of ice mechanical properties is significant for several areas of research such as glaciology, planetary sciences, but also in geosciences and metallurgy as ice can be seen as a model material with easier experimental handling at near melting temperatures. In the present study, we used torsion experiments to study non-coaxial shear strain (γ), very common in natural environments, up to very high values of γ. Numerous studies determined microstructure and texture evolution in polycrystalline assemblage submitted to torsion (metallic alloys and geological materials) but a very limited number focused on polycrystalline ice. Full cylinders of randomly oriented polycrystalline ice (grain size ~ 1 mm) were placed in a torsion apparatus and deformed under ductile regime under constant imposed torque at 266K (0.97 Tf). Macroscopic shear was monitored using a LVDT device or a rotary encoder. Several torsion tests with maximal shear strain up to γmax = 1 were performed. Tangent and axial sections were analyzed ex-situ using Automatic Ice Texture Analyzer (AITA) and Electron BackScatter Diffraction (EBSD). We were able to confirm the previously observed bimodal preferred orientation of the basal slip plane. Macroscopic strain evolution γ(t) displays a weakening after γmax = 0.04 (ɛmax ≃ 2 %), due to the beginning of dynamic recrystallization (DRX) processes. EBSD data provide novel informations on the microstructure that suggest very efficient grain boundary migration processes. In particular, we were able to measure differences of intra-granular misorientations density between the two ODF maxima populations that can highlight the role of DRX

  16. Torsional Elastic Property Measurements of Selected Orthodontic Archwires.

    DTIC Science & Technology

    1987-01-01

    replacing gold in the middle of the century. If the orthodontist wished to have lighter forces over a greater range, he had two choices. First, he...length. The orthodontist was forced to make torque adjustments in small increments with a large, torsionally stiff, stainless steel wire. The concept...slot, respectively) were measured with strain gauges. The expected linear relationship between the torque magnitude and the activation angle was verified

  17. Upright Perception and Ocular Torsion Change Independently during Head Tilt

    PubMed Central

    Otero-Millan, Jorge; Kheradmand, Amir

    2016-01-01

    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 12 subjects in upright position, during prolonged (~15 min) 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° and right tilt: +2.2 ± 2.1°). 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° and right tilt: +2.55 ± 1.0°). 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. PMID:27909402

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

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

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

  19. Metatarsal torsion in monkeys, apes, humans and australopiths.

    PubMed

    Drapeau, Michelle S M; Harmon, Elizabeth H

    2013-01-01

    This paper presents an analysis of metatarsal torsion in apes, cercopithecoids and humans, compares australopiths with these species, and discusses their inferred foot morphology and function relative to prehensility, arboreality and the presence or absence of a longitudinal arch. Our results show that locomotor modes are reflected in metatarsal torsion values. Apes, which climb vertically with their foot inverted, have hallucal metatarsal heads that are turned toward the other toes and lateral toes that are inverted. Cercopithecoids, which tend to orient their feet in an axis more parallel to the line of motion, present signs of prehensility by having inverted 2nd metatarsals that oppose the hallux, while their two lateral-most metatarsals are strongly everted. Humans, with their rigid feet and longitudinal arches, have all toes that present their plantar surface toward the ground, resulting in hallucal and 2nd metatarsals that are relatively untwisted and the others that are strongly everted. Humans are different from all taxa only for the 2nd and 3rd metatarsal. It is hypothesized that the untwisted 2nd metatarsal reflects the lack of digit opposability of the medial foot and the strongly everted 3rd metatarsal reflects the longitudinal arch. Australopithecus afarensis was characterized by an everted lateral foot, the prerequisite for the development, but not necessarily an indicator, of a longitudinal arch. In Australopithecus africanus, torsion of fragmentary and complete 1st, 2nd, 3rd and 5th metatarsals suggest that the species did not have a foot with monkey- or ape-like prehensile capabilities and did not have a human-like longitudinal arch. In the Swartkrans remains, torsion is consistent with an unprehensile foot. The morphology of the fossils indicates that there was strong selection to orient the plantar surface of the toes facing the ground at the expense of a grasping foot and inversion ability.

  20. Propagation and Reflection of Diffusionless Torsional Waves in a Sphere

    NASA Astrophysics Data System (ADS)

    Maffei, S.; Jackson, A.

    2015-12-01

    The magnetohydrodynamics of stars and planetary cores is usually dominated by the overwhelming importance of rotation compared to other forces. Under these conditions the fluid motions are characterized by a strong invariance along the rotation axis. In the presence of a background magnetic field, magnetohydrodynamic oscillations can be triggered. Among these, of particular interest are the torsional waves, azimuthal perturbations of the fluid that are axisymmetric and invariant along the vertical direction. Their periods depend solely on the intensity of the magnetic field component aligned with the radial direction of propagation. As the detection of the fundamental period could constrain the magnetic field intensity in the Earth's outer core there is a long history of attempted detection of torsional waves from geomagnetic data. There is however a fundamental lack of knowledge concerning the propagation and reflection properties of these waves, as observational studies suggests behaviors that are different from theoretical expectations. In particular, recent findings (Gillet et al., 2011) suggest the lack of reflection at the equator and at the rotation axis. Through numerical simulation and analytical techniques we analyze the temporal evolution of diffusionless torsional waves in spherical geometry, with particular attention on the reflection at the equator and the pseudo-reflection at the rotation axis. We develop a novel analytical solution to the torsional wave eigenvalue problem whose behavior at the boundaries helps us to illustrate the meaning of the boundary conditions. Furthermore we find that for any acceptable magnetic background field, reflections at both boundaries are allowed and we illustrate how the WKBJ approximation is an efficient tool for investigating them.

  1. Stability of Thin-Walled Tubes Under Torsion

    NASA Technical Reports Server (NTRS)

    Donnell, L H

    1935-01-01

    In this report a theoretical solution is developed for the torsion on a round thin-walled tube for which the walls become unstable. The results of this theory are given by a few simple formulas and curves which cover all cases. The differential equations of equilibrium are derived in a simpler form than previously found, it being shown that many items can be neglected.

  2. Testicular conditions in athletes: torsion, tumors, and epididymitis.

    PubMed

    Sandella, Bradley; Hartmann, Brett; Berkson, David; Hong, Eugene

    2012-01-01

    Individuals involved in sports are at risk for sustaining various injuries. In addition to musculoskeletal complaints, male athletes are at risk of incurring testicular injuries. These issues can range from an acute emergency such as testicular torsion to indolent testicular tumors. In contrast, epididymitis can present in stages. Presentation and management of testicular complaints can vary depending on the condition. Physicians who provide medical care to athletes need to be competent in diagnosing and managing testicular injuries.

  3. Self-accelerating universe in modified gravity with dynamical torsion

    NASA Astrophysics Data System (ADS)

    Nikiforova, V.; Randjbar-Daemi, S.; Rubakov, V.

    2017-01-01

    We consider a model belonging to the class of gravities with dynamical torsion. The model is free of ghosts and gradient instabilities about Minkowski and torsionless Einstein backgrounds. We find that at zero cosmological constant, the model admits a self-accelerating solution with a non-Riemannian connection. Small value of the effective cosmological constant is obtained at the expense of the hierarchy between the dimensionless couplings.

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

    PubMed

    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.

  5. Intravitreal Phacoemulsification Using Torsional Handpiece for Retained Lens Fragments

    PubMed Central

    Kumar, Vinod; Takkar, Brijesh

    2016-01-01

    Purpose: To evaluate the results of intravitreal phacoemulsification with torsional hand piece in eyes with posteriorly dislocated lens fragments. Methods: In this prospective, interventional case series, 15 eyes with retained lens fragments following phacoemulsification were included. All patients underwent standard three-port pars plana vitrectomy and intravitreal phacoemulsification using sleeveless, torsional hand piece (OZiL™, Alcon's Infiniti Vision System). Patients were followed up for a minimum of six months to evaluate the visual outcomes and complications. Results: The preoperative best-corrected visual acuity (BCVA) ranged from light perception to 0.3. No complications such as thermal burns of the scleral wound, retinal damage due to flying lens fragments, or difficult lens aspiration occurred during intravitreal phacoemulsification. Mean post-operative BCVA at the final follow-up was 0.5. Two eyes developed cystoid macular edema, which was managed medically. No retinal detachment was noted. Conclusion: Intravitreal phacoemulsification using torsional hand piece is a safe and effective alternative to conventional longitudinal phacofragmentation. PMID:27621783

  6. Friction and shear fracture of an adhesive contact under torsion

    NASA Astrophysics Data System (ADS)

    Chateauminois, Antoine; Fretigny, Christian; Olanier, Ludovic

    2010-02-01

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

  7. Oligothiophene wires: impact of torsional conformation on the electronic structure.

    PubMed

    Kislitsyn, D A; Taber, B N; Gervasi, C F; Zhang, L; Mannsfeld, S C B; Prell, J S; Briseno, A L; Nazin, G V

    2016-02-14

    Charge transport in polymer- and oligomer-based semiconductor materials depends strongly on the structural ordering of the constituent molecules. Variations in molecular conformations influence the electronic structures of polymers and oligomers, and thus impact their charge-transport properties. In this study, we used Scanning Tunneling Microscopy and Spectroscopy (STM/STS) to investigate the electronic structures of different alkyl-substituted oligothiophenes displaying varied torsional conformations on the Au(111) surface. STM imaging showed that on Au(111), oligothiophenes self-assemble into chain-like structures, binding to each other via interdigitated alkyl ligands. The molecules adopted distinct planar conformations with alkyl ligands forming cis- or trans- mutual orientations. For each molecule, by using STS mapping, we identify a progression of particle-in-a-box-like states corresponding to the LUMO, LUMO+1 and LUMO+2 orbitals. Analysis of STS data revealed very similar unoccupied molecular orbital energies for different possible molecular conformations. By using density functional theory calculations, we show that the lack of variation in molecular orbital energies among the different oligothiophene conformers implies that the effect of the Au-oligothiophene interaction on molecular orbital energies is nearly identical for all studied torsional conformations. Our results suggest that cis-trans torsional disorder may not be a significant source of electronic disorder and charge carrier trapping in organic semiconductor devices based on oligothiophenes.

  8. Development of a torsion balance for adhesion measurements

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Maeda, Chikayoshi; Masuo, Ryuichi

    1988-01-01

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

  9. Shape sensing for torsionally compliant concentric-tube robots

    NASA Astrophysics Data System (ADS)

    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.

  10. A Rare Emergency: Testicular Torsion in the Inguinal Canal

    PubMed Central

    Şener, Nevzat Can; Bas, Okan; Yesil, Suleyman; Zengin, Kursad; Imamoglu, Abdurrahim

    2015-01-01

    Objectives. To report our experience and present the largest series of testicular torsion cases in the inguinal canal. Material and Methods. The clinical data of 13 patients with testicular torsion in the inguinal canal treated between 2005 and 2013 were reviewed. Recorded patient age, whether the testes were palpable or not, side of the affected testes, the presence of hernia, ischemia time, and operation outcomes were assessed. Results. Patient age ranged from 8 to 70 months (29.15 ± 20.22). Mean ischemia time was 16.5 ± 21.3 hours. Accompanying inguinal hernia was present in 92% of the cases (12/13). Four of the thirteen patients (30.8%) were treated by orchiectomy because the necrosis was present after prolonged ischemia time. Nine patients (69.2%) were treated by single session orchidopexy. Conclusion. Torsion of testes in the inguinal canal is a rare disease, but with rapid diagnosis, affected testes can be salvaged, but the key factor is to keep this condition in mind. PMID:25654093

  11. Design of a smart superstructure FBG torsion sensor

    NASA Astrophysics Data System (ADS)

    Miclos, Sorin; Savastru, Dan; Savastru, Roxana; Lancranjan, Ion I.

    2015-05-01

    The paper presents the results obtained in simulation of a Superstructure Fiber Bragg Grating (SFBG) torsion sensor. The SFBG sensor simulation points to an improved smart composite or metallic parts design to be operated under torsion loads in various applications. SFBG sensor simulation consists of correlating the fiber deformation under applied mechanical loads with the modified FBG characteristic reflection spectrum considering the polarization mode variations. The analyzed SFBG is developed by the selective deposition of on-fiber periodic metal thin films on regular FBGs. The torsion mechanical loads induced shifts in the characteristic reflection spectrum of Bragg wavelength and side bands are analyzed. For obtaining information about an optimal structure of SFBG sensor, simulation is performed for four commercially available photosensitive single mode silica optical fibers having different geometric and optical characteristics, mainly core and clad refractive index values. It is considered that, by using an UV writing technique, Brag gratings are induced into the simulated SFBG. Simulations are performed considering different geometric characteristics of the shaft used as mechanical mount of SFBG. The simulation results are in fairly good agreement with the experimental ones reported in literature.

  12. Optical diagnosis of testicular torsion: feasibility and methodology

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  14. LISA technology development using the UF precision torsion pendulum

    NASA Astrophysics Data System (ADS)

    Apple, Stephen; Chilton, Andrew; Olatunde, Taiwo; Ciani, Giacomo; Mueller, Guido; Conklin, John

    2015-04-01

    LISA will directly observe low-frequency gravitational waves emitted by sources ranging from super-massive black hole mergers to compact galactic binaries. A laser interferometer will measure picometer changes in the distances between free falling test masses separated by millions of kilometers. A test mass and its associated sensing, actuation, charge control and caging subsystems are referred to as a gravitational reference sensor (GRS). The demanding acceleration noise requirement for the LISA GRS has motivated a rigorous testing campaign in Europe and a dedicated technology mission, LISA Pathfinder, scheduled for launch in the fall of 2015. At the University of Florida we are developing a nearly thermally noise limited torsion pendulum for testing GRS technology enhancements that may improve the performance and/or reduce the cost of the LISA GRS. This experimental facility is based on the design of a similar facility at the University of Trento, and consists of a vacuum enclosed torsion pendulum that suspends mock-ups of the LISA test masses, surrounded by electrode housings. Some of the technologies that will be demonstrated by this facility include a novel TM charge control scheme based on ultraviolet LEDs, an all-optical TM position and attitude sensor, and drift mode operation. This presentation will describe the design of the torsion pendulum facility, its current acceleration noise performance, and the status of the GRS technologies under development.

  15. Ocular torsion before and after 1 hour centrifugation.

    PubMed

    Groen, E; De Graaf, B; Bles, W; Bos, J E

    1996-01-01

    To assess a possible otolith contribution to effects observed following prolonged exposure to hypergravity, we used video oculography to measure ocular torsion during static and dynamic conditions of lateral body tilt (roll) before and after 1 h of centrifugation with a Gx-load of 3 G. Static tilt (from 0 to 57 degrees to either side) showed a 10% decrease in otolith-induced ocular torsion after centrifugation. This implies a reduced gain of the otolith function. The dynamic condition consisted of sinusoidal body roll (frequency 0.25 Hz, amplitude 45 degrees) about an earth horizontal and about an earth vertical axis (respectively, "with" and "without" otolith stimulation). Before centrifugation the gain of the slow component velocity (SCV) was significantly lower "with" otolith stimulation than "without" otolith stimulation. Apparently, the contribution of the otoliths counteracts the ocular torsion response generated by the semicircular canals. Therefore, the observed increase in SCV gain in the condition "with" otolith stimulation after centrifugation, seems in correspondence with the decreased otolith gain in the static condition.

  16. Rotational Energies in Various Torsional Levels of CH_2DOH

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.; Hilali, A. El; Margulès, L.; Motiyenko, R. A.; Klee, S.

    2012-06-01

    Using an approach accounting for the hindered internal rotation of a monodeuterated methyl group, an analysis of the torsional spectrum of the monodeuterated species of methanol CH_2DOH has been carried out recently and led to the assignment of 76 torsional subbands in its microwave, FIR, and IR spectra. Although this approach also allowed us to account for subband centers, the rotational structure of the torsional subbands is not well understood yet. In this paper, we will deal with the rotational energies of CH_2DOH. Analyses of the rotational structure of the available subbands^b have been performed using the polynomial-type expansion introduced in the case of the normal species of methanol. For each subband, FIR or IR transitions and a-type microwave lines, within the lower torsional level, were fitted. The frequencies of the latters were taken from previous investigations or from new measurements carried out from 50 to 950 GHz with the submillimeterwave solid state spectrometer in Lille. Subbands involving lower levels with v_t=0 and K ≥ 3 could be satisfactorily analyzed. For levels characterized by lower K-values, the expansion fails. In the case of the K=1, v_t=1 level, the frequencies of a-type microwave transitions involving the lower member of the K-type doublet cannot be well reproduced. For K=0 levels with v_t=1 and 2, a large number of terms is needed in the expansion. We will try to understand why the rotational energies of these levels cannot be reproduced. The results of the analyses will be compared to those obtained with a global approach based on the rotation-torsion Hamiltonian of the molecule. [2] El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. 135 (2011) 194309. [3] Ioli, Moruzzi, Riminucci, Strumia, Moraes, Winnewisser, and Winnewisser, J. Mol. Spec. 171 (1995) 130. [4] Quade and Suenram, J. Chem. Phys. 73 (1980) 1127; and Su and Quade, J. Mol. Spec. 134 (1989) 290. [5] Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spec. 256 (2009

  17. Torsion sensors of high sensitivity and wide dynamic range based on a graphene woven structure.

    PubMed

    Yang, Tingting; Wang, Yan; Li, Xinming; Zhang, Yangyang; Li, Xiao; Wang, Kunlin; Wu, Dehai; Jin, Hu; Li, Zhihong; Zhu, Hongwei

    2014-11-07

    Due to its unique electromechanical properties, nanomaterial has become a promising material for use in the sensing elements of strain sensors. Tensile strain is the type of deformation most intensively studied. Torsion is another deformation occurring in everyday life, but is less well understood. In the present study a torsion sensor was prepared by wrapping woven graphene fabrics (GWFs) around a polymer rod at a specific winding angle. The GWF sensor showed an ultra-high sensitivity with a detection limit as low as 0.3 rad m(-1), indicating its potential application in the precise measurement of low torsions. The GWFs were pre-strained before wrapping on polydimethylsiloxane (PDMS) to improve the tolerance of the sensor to high torsion. The microstructure of the GWFs at different torsion levels was monitored using an optical microscope. The results demonstrated the formation of GWF waves and cracks under high torsion, a critical factor in determining the electromechanical properties of a GWF sensor.

  18. Excitation of torsional modes of proteins via collisional energy transfer: A quantum dynamical approach

    NASA Astrophysics Data System (ADS)

    Clary, David C.; Meijer, Anthony J. H. M.

    2002-06-01

    Quantum dynamical calculations have been carried out on the excitation of the torsional vibrations of a protein by collision with a solvent molecule. This energy transfer process represents the first step in the unfolding of the protein. The method developed for this purpose is the torsional close coupling, infinite order sudden approximation. Both time-independent and time dependent methods are used to solve the scattering problem and individual excitation of all the torsional modes of the protein is treated. The method is applied to the excitation of the HIV protein gp41 colliding with a water molecule. This protein has 1101 atoms, 56 amino acids, and 452 torsional modes. A major mode-selective effect is found in the computations: it is much easier to excite backbone torsions than sidechain torsions in the protein. In addition, resonances arise in the collisional process and these complexes involve temporary trapping of the water molecule inside the pockets of the protein.

  19. Evidence that gastropod torsion is driven by asymmetric cell proliferation activated by TGF-beta signalling.

    PubMed

    Kurita, Yoshihisa; Wada, Hiroshi

    2011-10-23

    Gastropods are characterized by their asymmetric bodyplan, which develops through a unique ontogenetic process called 'torsion'. Despite several intensive studies, the driving force of torsion remains to be determined. Although torsion was traditionally believed to be driven by contraction of the retractor muscle connecting the foot and the shell, some recent reports cast doubt on that idea. Here, we report that torsion is accompanied by left-right asymmetric cell proliferation in the mantle epithelium in the limpet Nipponacmea fuscoviridis. Furthermore, we found that pharmacological inhibition of the transforming growth factor-β (TGF-β) signalling pathway, including that of Nodal, blocked torsion. We confirmed that the blocking was brought about through failure of the activation of cell proliferation in the right-hand side of the mantle epithelium, while the retractor muscle apparently developed normally. These results suggest that limpet torsion is driven by left-right asymmetric cell proliferation in the mantle epithelium, induced by the TGF-β pathway.

  20. Improving the sensitivity of a torsion pendulum by using an optical spring method

    SciTech Connect

    Wang Qinglan; Yeh Hsienchi; Zhou Zebing; Luo Jun

    2009-10-15

    We present a scheme aiming at improving the sensitivity of a torsion pendulum by means of radiation-pressure-induced optical spring. Two partial-reflective mirrors are installed on the opposite sides of a torsion pendulum, and one high-reflective mirror is mounted at the end of the torsion beam so that two identical Fabry-Perot cavities can be formed and aligned in series. Due to the antisymmetric radiation pressures acting on the opposite sides of the torsion beam, a negative restoring coefficient can be generated within a certain dynamic range, such that both the resultant torsional rigidity and the resonant frequency of the torsion pendulum are reduced, and the minimum detectable response torque in high-frequency region can be reduced accordingly.

  1. Molecular dynamics study of the torsional vibration characteristics of boron-nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Ajori, S.

    2014-08-01

    In recent years, synthesizing inorganic nanostructures such as boron nitride nanotubes (BNNTs) has led to extensive studies on their exceptional properties. In this study, the torsional vibration behavior of boron-nitride nanotubes (BNNTs) is explored on the basis of molecular dynamics (MD) simulation. The results show that the torsional frequency is sensitive to geometrical parameters such as length and boundary conditions. The axial vibration is found to be induced by torsional vibration of nanotubes which can cause instability in the nanostructure. It is also observed that the torsional frequency of BNNTs is higher than that of their carbon counterpart. Moreover, the shear modulus is predicted by incorporating MD simulation numerical results into torsional vibration frequency obtained through continuum-based model of tubes. Finally, it is seen that the torsional frequency of double-walled boron-nitride nanotubes (DWBNNTs) is between the frequencies of their constituent inner and outer tubes.

  2. Axial and torsional fatigue behavior of a cobalt-base alloy

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1991-01-01

    In order to develop elevated temperature multiaxial fatigue life prediction models for the wrought cobalt-base alloy, Haynes 188, a multiaxial fatigue data base is required. To satisfy this need, an elevated temperature experimental program on Haynes 188 consisting of axial, torsional, inphase and out of phase axial-torsional fatigue experiments was designed. Elevated temperature axial and torsional fatigue experiments were conducted under strain control on thin wall tubular specimens of Haynes 188 in air. Test results are given.

  3. Torsion Tests of 24S-T Aluminum-alloy Noncircular Bar and Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Paul, D A

    1943-01-01

    Tests of 24S-T aluminum alloy have been made to determine the yield and ultimate strengths in torsion of noncircular bar and tubing. An approximate basis for predicting these torsional strength characteristics has been indicated. The results show that the torsional stiffness and maximum shearing stresses within the elastic range may be computed quite closely by means of existing formulas based on mathematical analysis and the membrane analogy.

  4. Inferior Vena Cava Torsion and Stenosis Complicated by Compressive Pericaval Regional Ascites following Orthotopic Liver Transplantation

    PubMed Central

    Gilroy, Richard; Johnson, Philip

    2013-01-01

    Inferior vena cava (IVC) stenosis and torsion are well-described rare complications following orthotopic liver transplantation (OLT). We present a case of inferior vena cava intermittent torsion and stenosis complicated by compressive regional ascites. To the best of our knowledge, this is the second case of post-OLT regional ascites related compressive IVC stenosis reported and the first reported case of torsion complicated by regional ascites compression. PMID:24386585

  5. 3D Curves With a Prescribed Curvature and Torsion for a Flying Robot

    SciTech Connect

    Bestaoui, Yasmina

    2008-06-12

    The objective of this paper is to generate a desired flight path to be followed by an flying robot. A curve with discontinuous curvature and torsion is not appropriate for smooth motions for any vehicle architecture. Three different classes of curves are presented. First, constant curvature and torsion followed by a linear variation versus the curvilinear abscissa then a quadratic variation. Finally, the problem of maneuvers between two trim helices of different curvature and torsion is tackled with.

  6. Application of a boundary element method to the study of dynamical torsion of beams

    NASA Technical Reports Server (NTRS)

    Czekajski, C.; Laroze, S.; Gay, D.

    1982-01-01

    During dynamic torsion of beam elements, consideration of nonuniform warping effects involves a more general technical formulation then that of Saint-Venant. Nonclassical torsion constants appear in addition to the well known torsional rigidity. The adaptation of the boundary integral element method to the calculation of these constants for general section shapes is described. The suitability of the formulation is investigated with some examples of thick as well as thin walled cross sections.

  7. Eye torsion and visual tilt are mediated by different binocular processes

    NASA Technical Reports Server (NTRS)

    Wolfe, J. M.; Held, R.

    1979-01-01

    Viewing a large, patterned field rotating about the line of sight produces two measurable effects; cyclotorsion of the eyes (torsion) and a perceived displacement of vertical and horizontal (tilt). Experiments examining binocular interaction for these effects show: (1) both effects demonstrate summation in normal individuals and thus both involve a binocular process; (2) the process for tilt is different than for torsion, since summation for torsion is spared in stereodeficient individuals while that for tilt is eliminated.

  8. Extended torsional tests of an interlocked bi-stem satellite boom

    NASA Technical Reports Server (NTRS)

    Abercrombie, R. A.

    1973-01-01

    The effect is reported of continued oscillations of a 1.27-cm interlocked bi-stem satellite boom. The test setup oscillated a boom continuously between set torque limits and periodically recorded its hysteresis characteristics. Results showed that repeated oscillations affected torsional characteristics and that torsional rigidity changed as a function of the number of cycles oscillated within certain torque limits. Torsional characteristics changes caused by repeated oscillations were retained.

  9. Spontaneous formation of non-uniform double helices for elastic rods under torsion

    NASA Astrophysics Data System (ADS)

    Li, Hongyuan; Zhao, Shumin; Xia, Minggang; He, Siyu; Yang, Qifan; Yan, Yuming; Zhao, Hanqiao

    2017-02-01

    The spontaneous formation of double helices for filaments under torsion is common and significant. For example, the research on the supercoiling of DNA is helpful for understanding the replication and transcription of DNA. Similar double helices can appear in carbon nanotube yarns, cables, telephone wires and so forth. We noticed that non-uniform double helices can be produced due to the surface friction induced by the self-contact. Therefore an ideal model was presented to investigate the formation of double helices for elastic rods under torque. A general equilibrium condition which is valid for both the smooth surface and the rough surface situations is derived by using the variational method. By adding further constraints, the smooth and rough surface situations are investigated in detail respectively. Additionally, the model showed that the specific process of how to twist and slack the rod can determine the surface friction and hence influence the configuration of the double helix formed by rods with rough surfaces. Based on this principle, a method of manufacturing double helices with designed configurations was proposed and demonstrated. Finally, experiments were performed to verify the model and the results agreed well with the theory.

  10. Detection of testicular torsion by magnetic resonance imaging in a rat model.

    PubMed

    Landa, H M; Gylys-Morin, V; Mattery, R F; Hajek, P; Krous, H F; Kaplan, G W; Packer, M G

    1988-11-01

    Testicular torsion is one of the most common pediatric urological emergencies. Incorrect or delayed diagnosis contributes significantly to morbidity. We previously have shown that magnetic resonance displays scrotal contents with great detail using hydrogen concentration weighted and T2 weighted images. Sprague-Dawley rats underwent either unilateral 720-degree testicular torsion or a sham procedure. Magnetic resonance images were obtained at intervals with a 3 or 5-inch surface coil. Scans after surgical torsion showed a characteristic spiral distortion of the fascial planes of the spermatic cord, not seen in the sham animals, as well as a decrease in testicular size with prolonged torsion.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Torsion-sensing material from aligned carbon nanotubes wound onto a rod demonstrating wide dynamic range.

    PubMed

    Yamada, Takeo; Yamamoto, Yuki; Hayamizu, Yuhei; Sekiguchi, Atsuko; Tanaka, Hiroyuki; Kobashi, Kazufumi; Futaba, Don N; Hata, Kenji

    2013-04-23

    A rational torsion sensing material was fabricated by wrapping aligned single-walled carbon nanotube (SWCNT) thin films onto the surface of a rod with a predetermined and fixed wrapping angle without destroying the internal network of the SWCNTs within the film. When applied as a torsion sensor, torsion could be measured up to 400 rad/meter, that is, more than 4 times higher than conventional optical fiber torsion sensors, by monitoring increases in resistance due to fracturing of the aligned SWCNT thin films.

  13. The Research on the Impact of Green Beans Sports Drinks on Relieving Fatigue in Sports Training.

    PubMed

    Qi, Li; Ying, Liu

    2015-01-01

    For researching the function of relieving fatigue of green beans sports drinks, this paper selected 60 mice as subjects. They were randomly divided into four groups (low dose group, middle dose group, high dose group and physiological saline group). Each time they were respectively feed 10g 20g/L, 40g/L, 80 g/L green beans sports drinks and 15ml/(kg.d) physiological saline. The experiment lasted for a month. We recorded weight of mice, swimming time and blood urea nitrogen indicators. The results show that green beans sports drinks can significantly prolong swimming time of mice (p <0.05). For serum urea the results show no effect. So green beans sports drinks have a certain function of relieving physical fatigue.

  14. Effectiveness of a pressure-relieving mattress in an acute stroke ward.

    PubMed

    Gleeson, Deborah

    2016-11-10

    Between the 10 May and 18 July 2016, St Helens and Knowsley Teaching Hospitals NHS Trust conducted a small, non-controlled evaluation set out to assess the performance of the Apex Pro-care Auto pressure-relieving mattress in an acute stroke ward. Seven patients, assessed as being at medium-to-high risk of developing a pressure ulcer (PU), were recruited into the evaluation; the mean age was 73.1 years. Three patients were bed bound and four had restricted mobility. The average length of time spent on the mattress was 31 days. At the end of the evaluation, none of the patients had developed a PU while using the mattress. These results indicate that, when combined with a robust PU prevention plan inclusive of repositioning, this pressure-relieving mattress is effective in preventing pressure ulceration.

  15. Automatic stress-relieving music recommendation system based on photoplethysmography-derived heart rate variability analysis.

    PubMed

    Shin, Il-Hyung; Cha, Jaepyeong; Cheon, Gyeong Woo; Lee, Choonghee; Lee, Seung Yup; Yoon, Hyung-Jin; Kim, Hee Chan

    2014-01-01

    This paper presents an automatic stress-relieving music recommendation system (ASMRS) for individual music listeners. The ASMRS uses a portable, wireless photoplethysmography module with a finger-type sensor, and a program that translates heartbeat signals from the sensor to the stress index. The sympathovagal balance index (SVI) was calculated from heart rate variability to assess the user's stress levels while listening to music. Twenty-two healthy volunteers participated in the experiment. The results have shown that the participants' SVI values are highly correlated with their prespecified music preferences. The sensitivity and specificity of the favorable music classification also improved as the number of music repetitions increased to 20 times. Based on the SVI values, the system automatically recommends favorable music lists to relieve stress for individuals.

  16. Palmitoylethanolamide relieves pain and preserves pancreatic islet cells in a murine model of diabetes.

    PubMed

    Donvito, Giulia; Bettoni, Isabella; Comelli, Francesca; Colombo, Anita; Costa, Barbara

    2015-01-01

    We previously demonstrated that the intraperitoneal administration of palmitoylethanolamide (PEA) in mice with chronic constriction injury of the sciatic nerve evoked a relief of both thermal hyperalgesia and mechanical allodynia in neuropathic mice. Since diabetic neuropathy is one of the most common long-term complications of diabetes, we explored the ability of PEA to also relief this kind of chronic pain, employing the well established streptozotocin-induced animal model of type 1 diabetes. Our findings demonstrated that PEA relieves mechanical allodynia, counteracts nerve growth factor deficit, improves insulin level, preserves Langerhans islet morphology reducing the development of insulitis in diabetic mice. These results suggest that PEA could be effective in type 1-diabetic patients not only as pain reliever but also in controlling the development of pathology.

  17. A Numerical Investigation on the Response of Load Relieving Notches Subjected to Shock Wave Loading

    DTIC Science & Technology

    2013-09-01

    T WEERISOORIYA RDRL WMP C R BECKER S BILYK T BJERKE D CASEM J CLAYTON D DANDEKAR M GREENFIELD R LEAVY M...United States Air Force Project Rand, R -482-PR. [5] Nakayama, N., Ohashi, M., Sano, T., Horikoshi, S., Takeishi, H., 1997. Dynamic Stress Concentration...Optimization of Stress Relieving Notches. Journal of Strain Analysis Vol. 13 (3), p. 149. [7] Shea, R ., 1963. Dynamic Stress Concentration Factors. Watertown

  18. Well-Loved Music Robustly Relieves Pain: A Randomized, Controlled Trial

    PubMed Central

    Hsieh, Christine; Kong, Jian; Kirsch, Irving; Edwards, Robert R.; Jensen, Karin B.; Kaptchuk, Ted J.; Gollub, Randy L.

    2014-01-01

    Music has pain-relieving effects, but its mechanisms remain unclear. We sought to verify previously studied analgesic components and further elucidate the underpinnings of music analgesia. Using a well-characterized conditioning-enhanced placebo model, we examined whether boosting expectations would enhance or interfere with analgesia from strongly preferred music. A two-session experiment was performed with 48 healthy, pain experiment-naïve participants. In a first cohort, 36 were randomized into 3 treatment groups, including music enhanced with positive expectancy, non-musical sound enhanced with positive expectancy, and no expectancy enhancement. A separate replication cohort of 12 participants received only expectancy-enhanced music following the main experiment to verify the results of expectancy-manipulation on music. Primary outcome measures included the change in subjective pain ratings to calibrated experimental noxious heat stimuli, as well as changes in treatment expectations. Without conditioning, expectations were strongly in favor of music compared to non-musical sound. While measured expectations were enhanced by conditioning, this failed to affect either music or sound analgesia significantly. Strongly preferred music on its own was as pain relieving as conditioning-enhanced strongly preferred music, and more analgesic than enhanced sound. Our results demonstrate the pain-relieving power of personal music even over enhanced expectations. Trial Information Clinicaltrials.gov NCT01835275. PMID:25211164

  19. Mapping conformational dynamics of proteins using torsional dynamics simulations.

    PubMed

    Gangupomu, Vamshi K; Wagner, Jeffrey R; Park, In-Hee; Jain, Abhinandan; Vaidehi, Nagarajan

    2013-05-07

    All-atom molecular dynamics simulations are widely used to study the flexibility of protein conformations. However, enhanced sampling techniques are required for simulating protein dynamics that occur on the millisecond timescale. In this work, we show that torsional molecular dynamics simulations enhance protein conformational sampling by performing conformational search in the low-frequency torsional degrees of freedom. In this article, we use our recently developed torsional-dynamics method called Generalized Newton-Euler Inverse Mass Operator (GNEIMO) to study the conformational dynamics of four proteins. We investigate the use of the GNEIMO method in simulations of the conformationally flexible proteins fasciculin and calmodulin, as well as the less flexible crambin and bovine pancreatic trypsin inhibitor. For the latter two proteins, the GNEIMO simulations with an implicit-solvent model reproduced the average protein structural fluctuations and sample conformations similar to those from Cartesian simulations with explicit solvent. The application of GNEIMO with replica exchange to the study of fasciculin conformational dynamics produced sampling of two of this protein's experimentally established conformational substates. Conformational transition of calmodulin from the Ca(2+)-bound to the Ca(2+)-free conformation occurred readily with GNEIMO simulations. Moreover, the GNEIMO method generated an ensemble of conformations that satisfy about half of both short- and long-range interresidue distances obtained from NMR structures of holo to apo transitions in calmodulin. Although unconstrained all-atom Cartesian simulations have failed to sample transitions between the substates of fasciculin and calmodulin, GNEIMO simulations show the transitions in both systems. The relatively short simulation times required to capture these long-timescale conformational dynamics indicate that GNEIMO is a promising molecular-dynamics technique for studying domain motion in

  20. Mapping Conformational Dynamics of Proteins Using Torsional Dynamics Simulations

    PubMed Central

    Gangupomu, Vamshi K.; Wagner, Jeffrey R.; Park, In-Hee; Jain, Abhinandan; Vaidehi, Nagarajan

    2013-01-01

    All-atom molecular dynamics simulations are widely used to study the flexibility of protein conformations. However, enhanced sampling techniques are required for simulating protein dynamics that occur on the millisecond timescale. In this work, we show that torsional molecular dynamics simulations enhance protein conformational sampling by performing conformational search in the low-frequency torsional degrees of freedom. In this article, we use our recently developed torsional-dynamics method called Generalized Newton-Euler Inverse Mass Operator (GNEIMO) to study the conformational dynamics of four proteins. We investigate the use of the GNEIMO method in simulations of the conformationally flexible proteins fasciculin and calmodulin, as well as the less flexible crambin and bovine pancreatic trypsin inhibitor. For the latter two proteins, the GNEIMO simulations with an implicit-solvent model reproduced the average protein structural fluctuations and sample conformations similar to those from Cartesian simulations with explicit solvent. The application of GNEIMO with replica exchange to the study of fasciculin conformational dynamics produced sampling of two of this protein’s experimentally established conformational substates. Conformational transition of calmodulin from the Ca2+-bound to the Ca2+-free conformation occurred readily with GNEIMO simulations. Moreover, the GNEIMO method generated an ensemble of conformations that satisfy about half of both short- and long-range interresidue distances obtained from NMR structures of holo to apo transitions in calmodulin. Although unconstrained all-atom Cartesian simulations have failed to sample transitions between the substates of fasciculin and calmodulin, GNEIMO simulations show the transitions in both systems. The relatively short simulation times required to capture these long-timescale conformational dynamics indicate that GNEIMO is a promising molecular-dynamics technique for studying domain motion in

  1. Focal point analysis of torsional isomers of acrylic acid

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Postoperative Change in Ocular Torsion in Intermittent Exotropia: Relationship with Postoperative Surgical Outcomes

    PubMed Central

    Lee, Ju-Yeun; Hwang, Sungsoon; Oh, Shin Yeop; Park, Kyung-Ah; Oh, Sei Yeul

    2016-01-01

    The aim of this study was to determine whether objective ocular torsion in intermittent exotropia (IXT) changes after recession surgery, and to evaluate the relationship between change in ocular torsion and clinical parameters in IXT. Sixty patients between 3 and 14 years of age underwent lateral rectus (LR) recession for IXT. Digital fundus photographs were obtained from both eyes of each subject and the disc-foveal angle (ocular torsion) was calculated using image software. We compared the preoperative and postoperative amount of ocular torsion, and analyzed the correlation between the difference in ocular torsion (DOC) and clinical parameters including age, duration of strabismus, stereoacuity, amount of preoperative exodeviation, and mean dose response. We categorized the patients according to DOC value: positive DOC value as group 1, and negative DOC value as group 2. A correlation between ocular torsion dominance and fixation preference was also investigated using the Kappa test. The mean ocular torsion was 15.8 ± 4.6 degrees preoperatively and 13.7 ± 5.1 degrees postoperatively. Compared with preoperative values, the mean ocular torsion showed a significant decrease after LR recession (p<0.001), and a greater preoperative ocular torsion was significantly associated with the amount of DOC (r = 0.37, p<0.001). Degree of stereopsis, mean dose-response, and postoperative exodeviation were significantly different between group 1 (positive DOC) and group 2 (negative DOC) (p<0.001, 0.030, and 0.001 respectively). The Kappa test showed that there was a significant correlation between the dominance of ocular torsion and fixation preference (p = 0.020). Therefore, change in ocular torsion after LR recession can be a useful supplementary indicator for evaluating the degree of fusional control and for predicting postoperative surgical response in IXT. PMID:27622574

  5. Plastic welding techniques based on torsional and circular motion.

    PubMed

    Kising, J

    2001-05-01

    The torsion ultrasonic welding process and the frequency decoupled circular friction process at low frequencies deliver low particle production. In addition, the even, circular movement of the circular welding process over the whole seam area and the freely selectable frequency open up applications in the medical field that cannot be achieved, or can only be achieved with difficulty, by traditional welding processes. The processes are fast and can be process controlled to a fine degree with a facility to be integrated into automation lines.

  6. A Torsion-Balance Search for Axion-Like Particles

    NASA Astrophysics Data System (ADS)

    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.

  7. Femoral torsion and neck-shaft angles in cerebral palsy.

    PubMed

    Laplaza, F J; Root, L; Tassanawipas, A; Glasser, D B

    1993-01-01

    Excessive femoral and coxa valga have been reported to be major contributors leading to hip dislocation in patients with cerebral palsy (CP). Femoral torsion angle (FT) and neck-shaft angle (NSA) were measured by the radiographic technique described by Rippstein and Müller in 157 patients with CP (289 hips). Factors associated with the degree of FT and NSA were evaluated. The researchers explored the correlation between the two angles and hip pathology. A large database of measurements was constructed. Our findings suggest that age and ambulatory status are the main factors correlated with FT and NSA.

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

    DTIC Science & Technology

    2008-04-01

    Simulation of Friction Stir Weld Mictrstructures of a High Strength, Low Alloy Steel (HSLA-65),” Proceedings of the TWI 7th International FSW ...of HSLA-65 Steel by David R. Forrest and Matthew F. Sinfield N SW C C D -6 1- TR –2 00 8/ 02 N um er ic al S im ul at io n of G le eb le T or...Numerical Simulation of Gleeble Torsion Testing of HSLA-65 Steel by David R. Forrest and Matthew F. Sinfield i REPORT DOCUMENTATION PAGE Form

  9. Slip measurement in a frictional connection by torsional LDV

    NASA Astrophysics Data System (ADS)

    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

  10. Quantum gravity with torsion and non-metricity

    NASA Astrophysics Data System (ADS)

    Pagani, C.; Percacci, R.

    2015-10-01

    We study the renormalization of theories of gravity with an arbitrary (torsional and non-metric) connection. The class of actions we consider is of the Palatini type, including the most general terms with up to two derivatives of the metric, but no derivatives of the connection. It contains 19 independent parameters. We calculate the one-loop beta functions of these parameters and find their fixed points. The Holst subspace is discussed in some detail and found not to be stable under renormalization. Some possible implications for ultraviolet and infrared gravity are discussed.

  11. Cyclic Stress-Strain Studies of Metals in Torsion

    DTIC Science & Technology

    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

  12. Torsional Detwinning Domino in Nanotwinned One-Dimensional Nanostructures.

    PubMed

    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.

  13. Topological Behavior of Plasmid DNA.

    PubMed

    Higgins, N Patrick; Vologodskii, Alexander V

    2015-04-01

    The discovery of the B-form structure of DNA by Watson and Crick led to an explosion of research on nucleic acids in the fields of biochemistry, biophysics, and genetics. Powerful techniques were developed to reveal a myriad of different structural conformations that change B-DNA as it is transcribed, replicated, and recombined and as sister chromosomes are moved into new daughter cell compartments during cell division. This article links the original discoveries of superhelical structure and molecular topology to non-B form DNA structure and contemporary biochemical and biophysical techniques. The emphasis is on the power of plasmids for studying DNA structure and function. The conditions that trigger the formation of alternative DNA structures such as left-handed Z-DNA, inter- and intra-molecular triplexes, triple-stranded DNA, and linked catenanes and hemicatenanes are explained. The DNA dynamics and topological issues are detailed for stalled replication forks and for torsional and structural changes on DNA in front of and behind a transcription complex and a replisome. The complex and interconnected roles of topoisomerases and abundant small nucleoid association proteins are explained. And methods are described for comparing in vivo and in vitro reactions to probe and understand the temporal pathways of DNA and chromosome chemistry that occur inside living cells.

  14. Nonuniform Shear Strains in Torsional Kolsky Bar Tests on Soft Specimens

    DTIC Science & Technology

    2015-02-01

    ARL-RP-0519 ● FEB 2015 US Army Research Laboratory Nonuniform Shear Strains in Torsional Kolsky Bar Tests on Soft Specimens...originator. ARL-RP-0519 ● FEB 2015 US Army Research Laboratory Nonuniform Shear Strains in Torsional Kolsky Bar Tests on Soft Specimens...

  15. Highly Accurate Beam Torsion Solutions Using the p-Version Finite Element Method

    NASA Technical Reports Server (NTRS)

    Smith, James P.

    1996-01-01

    A new treatment of the classical beam torsion boundary value problem is applied. Using the p-version finite element method with shape functions based on Legendre polynomials, torsion solutions for generic cross-sections comprised of isotropic materials are developed. Element shape functions for quadrilateral and triangular elements are discussed, and numerical examples are provided.

  16. Torsional Control of Stereoselectivities in Electrophilic Additions and Cycloadditions to Alkenes

    PubMed Central

    Wang, Hao; Houk, K. N.

    2013-01-01

    Torsional effects control the π-facial stereoselectivities of a variety of synthetically important organic reactions. This review surveys theoretical calculations that have led to the understanding of the influence of the torsional effects on several types of stereoselective organic reactions, especially electrophilic additions and cycloadditions to alkenes. PMID:24409340

  17. Effective Torsion and Spring Constants in a Hybrid Translational-Rotational Oscillator

    ERIC Educational Resources Information Center

    Nakhoda, Zein; Taylor, Ken

    2011-01-01

    A torsion oscillator is a vibrating system that experiences a restoring torque given by [tau] = -[kappa][theta] when it experiences a rotational displacement [theta] from its equilibrium position. The torsion constant [kappa] (kappa) is analogous to the spring constant "k" for the traditional translational oscillator (for which the restoring force…

  18. Intermittent torsion of accessory hepatic lobe: An unusual cause of recurrent right upper quadrant pain.

    PubMed

    Jambhekar, Kedar; Pandey, Tarun; Kaushik, Chhavi; Shah, Hemendra R

    2010-05-01

    An accessory lobe of the liver is a rare congenital anomaly that can undergo torsion and present as an acute surgical emergency. It is rarely diagnosed preoperatively. We report the preoperative utility of CT scan and MRI in the diagnosis and surgical planning of a case of intermittent accessory hepatic lobe torsion.

  19. Torsion of Undescended Third Testis, as Rare Cause of Painful Inguinal Mass

    PubMed Central

    Nasrallah, Najib

    2015-01-01

    Twenty years old young was referred to our department due to painful inguinal mass. The mass was diagnosed as torsion of third testis which was treated by orchiectomy. Polyorchidism is a rare entity with increased risk for malignancy and torsion. PMID:25688325

  20. Autoantibodies against Leydig cells in patients after spermatic cord torsion.

    PubMed Central

    Zanchetta, R; Mastrogiacomo, I; Graziotti, P; Foresta, C; Betterle, C

    1984-01-01

    This study is aimed at searching for the presence of circulating antibodies against frozen sections of human testis, ovary and trophoblast in patients that had spermatic cord torsion. Sixty-eight sera samples were studied. Nine patients (13.2%) were positive for organ specific anti-testis autoantibodies. Six patients were positive for antibodies against Leydig cells: five were positive only with the indirect immunofluorescence technique of complement fixing (ITT/CF), the sixth patient was positive only with the indirect immunofluorescence technique (ITT). The other three patients were positive for antibodies against germ line cells: two patients were positive with both techniques, the third was positive only with indirect immunofluorescence technique. Eight of these patients were negative for antibodies against adrenal cortex while only one case was positive with indirect immunofluorescence technique both on adrenal cortex and Leydig cells. Human lyophilized testis absorbed the reactive antibodies against Leydig cells and germ line cells, while adrenal cortex and lyophilized testosterone were ineffective. This study shows the identification of a specific antibody against Leydig cells and germ line cells in patients after spermatic cord torsion. PMID:6362937

  1. Laparoscopic management of a two staged gall bladder torsion

    PubMed Central

    Sunder, Yadav Kamal; Akhilesh, Sali Priyanka; Raman, Garg; Deborshi, Sharma; Shantilal, Mehta Hitesh

    2015-01-01

    Gall bladder torsion (GBT) is a relatively uncommon entity and rarely diagnosed preoperatively. A constant factor in all occurrences of GBT is a freely mobile gall bladder due to congenital or acquired anomalies. GBT is commonly observed in elderly white females. We report a 77-year-old, Caucasian lady who was originally diagnosed as gall bladder perforation but was eventually found with a two staged torsion of the gall bladder with twisting of the Riedel’s lobe (part of tongue like projection of liver segment 4A). This together, has not been reported in literature, to the best of our knowledge. We performed laparoscopic cholecystectomy and she had an uneventful post-operative period. GBT may create a diagnostic dilemma in the context of acute cholecystitis. Timely diagnosis and intervention is necessary, with extra care while operating as the anatomy is generally distorted. The fundus first approach can be useful due to altered anatomy in the region of Calot’s triangle. Laparoscopic cholecystectomy has the benefit of early recovery. PMID:26730287

  2. A MEMS torsion magnetic sensor with reflective blazed grating integration

    NASA Astrophysics Data System (ADS)

    Long, Liang; Zhong, Shaolong

    2016-07-01

    A novel magnetic sensor based on a permanent magnet and blazed grating is presented in this paper. The magnetic field is detected by measuring the diffracted wavelength of the blazed grating which is changed by the torsion motion of a torsion sensitive micro-electromechanical system (MEMS) structure with a permanent magnet attached. A V-shape grating structure is obtained by wet etching on a (1 0 0) SOI substrate. When the magnet is magnetized in different directions, the in-plane or out-of-plane magnetic field is detected by a sensor. The MEMS magnetic sensor with a permanent magnet is fabricated after analytical design and bulk micromachining processes. The magnetic-sensing capability of the sensor is tested by fiber-optic detection system. The result shows the sensitivities of the in-plane and out-of-plane magnetic fields are 3.6 pm μT-1 and 5.7 pm μT-1, respectively. Due to utilization of the permanent magnet and fiber-optic detection, the sensor shows excellent capability of covering the high-resolution detection of low-frequency signals. In addition, the sensitive direction of the magnetic sensor can be easily switched by varying the magnetized direction of the permanent magnet, which offers a simple way to achieve tri-axis magnetic sensor application.

  3. Spinning optical resonator sensor for torsional vibrational applications measurements

    NASA Astrophysics Data System (ADS)

    Ali, Amir R.; Gatherer, Andrew; Ibrahim, Mariam S.

    2016-03-01

    Spinning spherical resonators in the torsional vibrational applications could cause a shift in its whispering gallery mode (WGM). The centripetal force acting on the spinning micro sphere resonator will leads to these WGM shifts. An analysis and experiment were carried out in this paper to investigate and demonstrate this effect using different polymeric resonators. In this experiment, centripetal force exerted by the DC-Motor on the sphere induces an elastic deformation of the resonator. This in turn induces a shift in the whispering gallery modes of the sphere resonator. Materials used for the sphere are polydimethylsiloxane (PDMS 60:1 where 60 parts base silicon elastomer to 1 part polymer curing agent by volume) with shear modulus (G≍1kPa), (PDMS 10:1) with shear modulus (G≍300kPa), polymethylmethacrylate (PMMA, G≍2.6×109GPa) and silica (G≍3×1010 GPa). The sphere size was kept constant with 1mm in diameter for all above materials. The optical modes of the sphere exit using a tapered single mode optical fiber that is coupled to a distributed feedback laser. The transmission spectrum through the fiber is monitored to detect WGM shifts. The results showed the resonators with smaller shear modulus G experience larger WGM shift due to the larger mechanical deformation induced by the applied external centripetal force. Also, the results show that angular velocity sensors used in the torsional vibrational applications could be designed using this principle.

  4. Determination of transverse shear strength through torsion testing

    SciTech Connect

    Marcucelli, K.T.; Fish, J.C.

    1997-12-31

    The in-plane characterization of composite materials is, in general, well understood and widely utilized throughout the aerospace industry. However, the use of composites in structural elements such as fuselage frames and rotorcraft flexbeams place large out-of-plane or through-the-thickness stresses for which there is little data. Efforts to determine the interlaminar shear strength of laminated composites have been hampered due to the nonlinear behavior of test specimens and the limitations of current analysis tools. An inexpensive rectangular torsion test specimen was designed to determine the interlaminar shear strength, s{sub 23}, of composite materials. Six different layups were fabricated of AS4/2220-3 carbon/epoxy unidirectional tape and tested in pure torsion. All of the specimens failed abruptly with well-defined shear cracks and exhibited linear load-deflection behavior. A quasi-three-dimensional (Q-3-D) finite element analysis was conducted on each of the specimen configurations to determine the interlaminar shear stress at failure. From this analysis, s{sub 23} was found to be 107 MPa for this material.

  5. From Tucking to Twisting; A Case of Self-induced Testicular Torsion in a Cross Dressing Male.

    PubMed

    Epps, Thomas; McCormick, Barrett; Ali, Antar; Duboy, Alberto; Gillen, James; Martinez, Daniel; Carrion, Rafael

    2016-07-01

    A self-induced, non-traumatic testicular torsion is a rare entity that to our knowledge has not been reported in the literature. We report the case of a 28-year-old male who caused a self-induced testicular torsion during acts associated with cross dressing. Differential diagnosis of the acute scrotum in an adult should always include testicular torsion, as outcomes in this population are worse than in younger populations. Additional unusual causes of testicular torsion are reviewed.

  6. Analysis on volume invariability of metal circular shaft in torsion deformation

    NASA Astrophysics Data System (ADS)

    Yang, Li-Hong; Zou, Guang-Ping; He, Yun-Zeng; Wang, Hui

    2009-12-01

    Volume invariability of metal circular shaft in the case of small strain torsion deformation and large strain torsion deformation was, respectively, discussed experimentally and theoretically in this study. In accordance with the elastoplastic theory, it was given that the shear stress did not cause the change of volume in the large strain range. By utilizing torsion experiment with the solid shaft of low carbon steel, it was proved that metal can meet the conditions of the volume invariability in torsion deformation while the cumulative damage was not very serious. Volumetric deformation was analyzed in torsion of circular shaft in the perspective of micromechanics. Finally, Swift effect of solid circular shaft and tubular shaft of brass material were interpreted by using the formulae of elastoplastic critic load obtained from double-limb bar model test presented by Shanley.

  7. Analysis on volume invariability of metal circular shaft in torsion deformation

    NASA Astrophysics Data System (ADS)

    Yang, Li-Hong; Zou, Guang-Ping; He, Yun-Zeng; Wang, Hui

    2010-03-01

    Volume invariability of metal circular shaft in the case of small strain torsion deformation and large strain torsion deformation was, respectively, discussed experimentally and theoretically in this study. In accordance with the elastoplastic theory, it was given that the shear stress did not cause the change of volume in the large strain range. By utilizing torsion experiment with the solid shaft of low carbon steel, it was proved that metal can meet the conditions of the volume invariability in torsion deformation while the cumulative damage was not very serious. Volumetric deformation was analyzed in torsion of circular shaft in the perspective of micromechanics. Finally, Swift effect of solid circular shaft and tubular shaft of brass material were interpreted by using the formulae of elastoplastic critic load obtained from double-limb bar model test presented by Shanley.

  8. Contemporary Review of Testicular Torsion: New Concepts, Emerging Technologies and Potential Therapeutics

    PubMed Central

    DaJusta, Daniel; Granberg, Candace F.; Villanueva, Carlos; Baker, Linda A.

    2012-01-01

    Testicular torsion is one of the few emergencies in pediatric urology which requires an accurate and timely diagnosis in order to avoid testis loss. It is not an uncommon event affecting a young male population. In fact, testicular torsion is more common than testicular tumors for this same age group, yet testicular torsion has not been given the public attention it deserves as a male health risk. In this review we highlight the new information published over the past four years regarding testicular torsion. We will discuss a variety of topics associated with torsion including: medical legal issues, etiology and genetics, imaging diagnostics, innovative surgical techniques, management controversies, fertility, and new drug therapies. PMID:23044376

  9. Torsion effect of swing frame on the measurement of horizontal two-plane balancing machine

    NASA Astrophysics Data System (ADS)

    Wang, Qiuxiao; Wang, Dequan; He, Bin; Jiang, Pan; Wu, Zhaofu; Fu, Xiaoyan

    2017-03-01

    In this paper, the vibration model of swing frame of two-plane balancing machine is established to calculate the vibration center position of swing frame first. The torsional stiffness formula of spring plate twisting around the vibration center is then deduced by using superposition principle. Finally, the dynamic balancing experiments prove the irrationality of A-B-C algorithm which ignores the torsion effect, and show that the torsional stiffness deduced by experiments is consistent with the torsional stiffness calculated by theory. The experimental datas show the influence of the torsion effect of swing frame on the separation ratio of sided balancing machines, which reveals the sources of measurement error and assesses the application scope of A-B-C algorithm.

  10. Bilateral segmental aplasia with unilateral uterine horn torsion in a Pomeranian bitch.

    PubMed

    Nakamura, Kensuke; Yamasaki, Masahiro; Osaki, Tomohiro; Ohta, Hiroshi; Sasaki, Noboru; Aoshima, Keisuke; Kimura, Takashi; Takiguchi, Mitsuyoshi

    2012-01-01

    Bilateral segmental aplasia of the uterine horns with unilateral pyometra and uterine horn torsion were diagnosed in a Pomeranian bitch that presented with chronic abdominal distension and an acute onset of anorexia and lethargy. Because radiographic and ultrasonographic findings revealed the presence of markedly enlarged bilateral uterine horns filled with fluid in the caudal abdomen, a tentative diagnosis of either pyometra or hydrometra with uterine horn torsion was made. Exploratory laparotomy showed bilateral, segmentally distended uterine horns with unilateral uterine horn torsion. Ovariohysterectomy was performed, and bilateral segmental aplasia of the uterine horns with the development of unilateral uterine horn torsion was diagnosed histopathologically. To the authors' knowledge, this is the first report of uterine horn torsion in conjunction with segmental aplasia of the uterine horn in a bitch.

  11. Torsional diffusion Monte Carlo: A method for quantum simulations of proteins

    NASA Astrophysics Data System (ADS)

    Clary, David C.

    2001-06-01

    The quantum diffusion Monte Carlo (DMC) method is extended to the treatment of coupled torsional motions in proteins. A general algorithm and computer program has been developed by interfacing this torsional-DMC method with all-atom force-fields for proteins. The method gives the zero-point energy and atomic coordinates averaged over the coupled torsional motions in the quantum ground state of the protein. Application of the new algorithm is made to the proteins gelsolin (356 atoms and 142 torsions) and gp41-HIV (1101 atoms and 452 torsions). The results indicate that quantum-dynamical effects are important for the energies and geometries of typical proteins such as these.

  12. Perinatal testicular torsion: preoperative radiological findings and the argument for urgent surgical exploration.

    PubMed

    Ahmed, Sally J; Kaplan, George W; DeCambre, Marvalyn E

    2008-08-01

    Perinatal testicular torsion is an infrequent event, the management of which has been controversial. Occurrence is rare, estimated at 1 in 7500 newborns (Kaplan, G. W., Silber, I.: Neonatal torsion--to pex or not? In: Urologic surgery in neonates and young infants. Edited by King, L.R. Philadelphia: W.B. Saunders Co., 1988; Chapter 20, pp. 386-395). The frequency of bilateral perinatal torsion is up to 22% (J Urol. 2005;174:1579). Here, we describe two cases of bilateral asynchronous perinatal torsion, in which the only presenting abnormality on exam after birth was a unilateral scrotal mass. These cases illustrate that contralateral perinatal torsion may be present even when physical exam findings suggest unilateral involvement.

  13. HIGH-LATITUDE SOLAR TORSIONAL OSCILLATIONS DURING PHASES OF CHANGING MAGNETIC CYCLE AMPLITUDE

    SciTech Connect

    Rempel, M.

    2012-05-01

    Torsional oscillations are variations of the solar differential rotation that are strongly linked to the magnetic cycle of the Sun. Helioseismic inversions have revealed significant differences in the high-latitude branch of torsional oscillations between cycle 23 and cycle 24. Here we employ a non-kinematic flux-transport dynamo model that has been used previously to study torsional oscillations and simulate the response of the high-latitude branch to a change in the amplitude of the magnetic cycle. It is found that a reduction of the cycle amplitude leads to an increase in the amplitude of differential rotation that is mostly visible as a drop in the high-latitude rotation rate. Depending on the amplitude of this adjustment the high-latitude torsional oscillation signal can become temporarily hidden due to the unknown changing mean rotation rate that is required to properly define the torsional oscillation signal.

  14. Long-range excitons in conjugated polymers with ring torsions: poly( para-phenylene) and polyaniline

    NASA Astrophysics Data System (ADS)

    Harigaya, Kikuo

    1998-08-01

    Ring torsion effects on the optical excitation properties of poly( para-phenylene) (PPP) and polyaniline (PAN) are investigated by extending the Shimoi-Abe model (Shimoi Y and Abe S 1996 Synth. Met. 78 219). The model is solved using the intermediate-exciton formalism. Long-range excitons are characterized, and the long-range component of the oscillator strengths is calculated. We find that ring torsions affect the long-range excitons in PAN more readily than those in PPP, due to the larger torsion angle of PAN and the large number of bonds whose hopping integrals are modulated by torsions. Next, ring torsional disorder effects simulated by the Gaussian distribution function are analysed. The long-range component of the total oscillator strengths after sample averaging is nearly independent of the disorder strength in the PPP case, while that in the PAN case decreases readily as the disorder becomes stronger.

  15. Direct observation of methyl rotor and vib-rotor states of S0 toluene: a revised torsional barrier due to torsion-vibration coupling.

    PubMed

    Gascooke, Jason R; Virgo, Edwina A; Lawrance, Warren D

    2015-01-14

    We report a two dimensional, laser induced fluorescence study of the lowest 345 cm(-1) region of S0 toluene. Methyl rotor levels of 00 up to m = 6 and of 201 up to m = 4 are observed. The rotor levels of 00 and 201 have quite different energy spacings that are well fit by a model that includes strong torsion-vibration coupling between them. The model requires that the rotor barrier height be revised from -4.84 cm(-1) (methyl hydrogens in a staggered conformation) to +1.57 cm(-1) (eclipsed conformation). However, the 3a2″ state lies below the 3a1″ state as expected for a staggered conformation due to energy shifts associated with the torsion-vibration coupling. It is shown that the rotor wave-functions exhibit little localization at the torsional energy minima. The variation in the m = 0 wavefunction probability distribution with torsional angle is shown to be very similar for the previously accepted negative V6 value and the torsion-vibration coupling model as this coupling shifts the phase of the wavefunction by 30° compared with its phase for V6 alone. The presence of a strong Δυ = ± 1 torsion-vibration coupling involving the lowest frequency vibrational mode provides a potential pathway for rapid intramolecular vibrational energy redistribution at higher energies.

  16. Effect of Different Levels of Pressure Relieving Air-Mattress Firmness on Cough Strength.

    PubMed

    Kamikawa, Norimichi; Taito, Shunsuke; Takahashi, Makoto; Sekikawa, Kiyokazu; Hamada, Hironobu

    2016-01-01

    Cough is an important host-defense mechanism. The elderly and patients who are severely ill cannot cough effectively when lying in the supine position. Furthermore, pressure relieving air-mattresses are recommended for preventing the development of pressure ulcers. In this study, we clarified whether or not the cough peak flow (CPF), an index of cough strength, is affected by different firmness levels of a pressure relieving air-mattress in healthy volunteers in the supine position. Fifty-two healthy young men participated. All the measurements were carried out on each participant in the supine position on a pressure relieving air-mattress. The participants were assessed at two firmness levels, a "hard" and "soft" mode. The CPF, forced vital capacity (FVC), maximal expiratory pressure (PEmax), and maximal inspiratory pressure (PImax) were determined for each mode. The sinking distance of the body into the mattress was measured without any activity and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax, and PImax were determined for each mode. The sinking distance of the body into the mattress was measured and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax and PImax values of the participants coughing on the mattress were significantly lower when the mattress was in "soft" than in "hard" mode. The differences between the sinking distances of the mattress in "soft" and "hard" modes were larger for the anterior superior iliac spine. A harder mattress may lead to increased CPF in healthy young men lying in the supine position, and increased CPF may be important for host defense.

  17. Fluorescence spectroscopic studies of DNA dynamics

    SciTech Connect

    Scalettar, B.A.

    1987-04-01

    Random solvent induced motions of DNA are manifest as nanosecond torsional oscillations of the helix backbone, nanosecond through millisecond bending deformations and overall rotational and translational diffusion of the polymer. Fluorescence spectroscopy is used to study this spectrum of DNA motions while ethidium monoazide was covalently bounded. The steady state fluorescence depolarization data indicate that the covalent monoazide/DNA complex exhibits internal motions characterized by an average angular amplitude of 26 degrees confirming reports of fast torsional oscillations in noncovalent ethidium bromide/DNA systems. Data obtained by use of a new polarized photobleaching recovery technique (FPR) reflect both the rotational dynamics of the polymer and the reversible photochemistry of the dye. To isolate the reorientational motion of the DNA, the FPR experiments were ran in two modes that differ only in the polarization of the bleaching light. A quotient function constructed from the data obtained in these two modes monitors only the rotational component of the FPR recovery. In specific applications those bending deformations of long DNA molecules that have characteristic relaxation times on the order of 100 microseconds have been resolved. A fluorescence correlation technique that relates fluctuations in particle number to center-of-mass motion was used to measure translational diffusion on coefficients of the plasmid PBR322 and a short oligomeric DNA. A theory that describes angular correlation in systems exhibiting cyclic, biologically directed reorientation and random Brownian rotation is developed.

  18. Benign coital headache relieved by partner's pregnancies with implications for future treatment.

    PubMed

    Dexter, Selwyn

    2010-01-01

    This is a case of a male patient with a 27 year history of severe benign coital headache and associated symptoms. His condition was spontaneously relieved in the first trimester of his partner's pregnancy. This relief continued through the remainder of the pregnancy term, returning only after the birth of their child. The timing of the condition's relief and return of symptoms suggested progesterone was an intrinsic factor in this. Post-pregnancy the patient was able to prevent his attacks by taking oral norethisterone 5 mg. While writing this case the patient's partner became pregnant once more, resulting again in spontaneous relief of the patient's syndrome.

  19. Oxidative Stress during Ovarian Torsion in Pediatric and Adolescent Patients: Changing The Perspective of The Disease

    PubMed Central

    Laganà, Antonio Simone; Sofo, Vincenza; Salmeri, Francesca Maria; Palmara, Vittorio Italo; Triolo, Onofrio; Terzić, Milan Milosav; Patrelli, Tito Silvio; Lukanovic, Adolf; Bokal, Eda Vrtcnik; Santoro, Giuseppe

    2016-01-01

    Among the different causes of gynecological acute pelvic pain, ovarian torsion represents a surgical emergency. It is a rare case in the pediatric/adolescent aged group that must be included in the differential diagnosis of any girl with abdominal pain or pelvic/abdominal mass. Current recommendations suggest that laparoscopic detorsion should be performed in order to preserve the integrity of the ovaries and fertility, although oophoropexy may be considered in case of severe necrosis. Nevertheless, maintaining the circulation of the ovary after detorsion deteriorates the tissue injury and leads to a pathologic process called ischaemia/reperfusion (I/R) injury, which is characterized by oxidative stress. During the detorsion process, an excess amount of molecular oxygen is supplied to the tissues, and reactive species of oxygen (ROS) such as superoxide radical (O2-), hydrogen peroxide (H2O2), hydroxyl radical (OH•), as well as reactive nitrogen species (RNS) are produced in excess. ROS, RNS and their toxic products cause DNA damage and lipid peroxidation in the cellular and mitochondrial membranes, leading to cell death. In spite of attention on this topic, currently there is no shared and clear evidence about the use of anti-inflammatory and antioxidant agents to prevent I/R damage after laparoscopic ovarian detorsion. Considering this element, future research should aim to develop shared protocols for the clinical use (route of application, dosage and time of application) of antioxidants after laparoscopic management of this condition. PMID:26985329

  20. Shaping van der Waals nanoribbons via torsional constraints: Scrolls, folds and supercoils

    PubMed Central

    Shahabi, Alireza; Wang, Hailong; Upmanyu, Moneesh

    2014-01-01

    Interplay between structure and function in atomically thin crystalline nanoribbons is sensitive to their conformations yet the ability to prescribe them is a formidable challenge. Here, we report a novel paradigm for controlled nucleation and growth of scrolled and folded shapes in finite-length nanoribbons. All-atom computations on graphene nanoribbons (GNRs) and experiments on macroscale magnetic thin films reveal that decreasing the end distance of torsionally constrained ribbons below their contour length leads to formation of these shapes. The energy partitioning between twisted and bent shapes is modified in favor of these densely packed soft conformations due to the non-local van der Waals interactions in these 2D crystals; they subvert the formation of supercoils that are seen in their natural counterparts such as DNA and filamentous proteins. The conformational phase diagram is in excellent agreement with theoretical predictions. The facile route can be readily extended for tailoring the soft conformations of crystalline nanoscale ribbons, and more general self-interacting filaments. PMID:25417759

  1. Torsionally Excited Dimethyl Ether in the Laboratory and in Space

    NASA Astrophysics Data System (ADS)

    Endres, C. P.; Müller, H. S. P.; Lewen, F.; Giesen, T. F.; Schlemmer, S.; Drouin, B. J.; Bisschop, S.; Groner, P.

    2010-06-01

    Dimethyl ether (DME) is highly abundant in hot cores and numerous transitions within the vibrational ground state have been detected in various interstellar line surveys of sources such as Orion KL. As a nearly prolate asymmetric top with two internal rotors, it shows a complex spectrum with low lying torsional modes. The energy levels of the two lowest torsional states (v11, and v15) lie only 200 and 240 cm-1 above the ground state (barrier height ≈ 915 cm-1), and are thus sufficiently populated in these interstellar sources to exhibit transitions in line surveys due to high excitation temperatures in hot cores. So far, the lack of sufficiently accurate predictions for the two lowest excited torsional states prevented their identification in astronomical spectra. Therefore, we analyzed spectra, which have been recorded within the context of the investigations of the ground state. In total, more than 9500 transitions have been assigned covering the frequency range from 38 up to 1670 GHz. The enlarged splitting of each rotational level into four substates (AA, EE, AE, EA) compared to its size in the ground state and a large number of perturbed transitions hampered not only the line assignment but also the astrophysical modelling. However, the inclusion of interaction terms between both excited states in the model of an effective Hamiltonian for a symmetric two-top rotor, allowed us to model both excited states within a global fit, and also to accurately determine the energy difference between both states. Frequency predictions have been calculated based on this analysis and have been used to unambiguously assign numerous rotational transitions within these excited states in the astronomical line survey of the hot core region G327.3-0.6. P. Schilke, T.D. Groesbeck et al., Astrophys.J.Suppl.Ser., 108,(1997) 301-337 P. Schilke, D.J. Benford, T.R. Hunter et al., Astrophys.J.Suppl.Ser., 132,(2001) 281-364. P. Groner, S. Albert, E. Herbst, and F.C. De Lucia, Astrophys

  2. Pain-relieving factors in migraine and tension-type headache.

    PubMed

    Bag, B; Karabulut, N

    2005-07-01

    We performed the present study to compare patients with migraine and tension-type headache (TTH) in their behaviour during the attacks and the manoeuvres to relieve the pain. One hundred thirty consecutive patients with either migraine (n = 75) or TTH (n = 55) were questioned (including the use of a checklist) concerning their usual behaviour during the attacks and non-pharmacological manoeuvres performed to relieve the pain. The results of the two types of headache were compared. Patients with migraine tended to perform more manoeuvres than patients with TTH (mean: 4.3 vs. 3.6). These manoeuvres included pressing and applying cold stimuli to the painful site, trying to sleep, changing posture, sitting or reclining in bed (using more pillows than usual to lay down), isolating themselves, using symptomatic medication, inducing vomiting, changing diet and becoming immobile during the attacks. The only measure predominantly reported by patients with TTH was scalp massage. Migraineurs, compared to patients with TTH, changing eating habits, pressed the pain site; there were no significant differences between the two groups. The behaviour of patients during headache attacks varies with the diagnosis. Measures that do not always result in pain relief are performed in order to prevent its worsening or to improve associated symptoms. These behavioural differences may be because of the different pathogenesis of the attacks or of various styles of dealing with the pain. They can also aid the differential diagnosis between headaches in doubtful cases.

  3. High-Pressure Torsion to Improve Thermoelectric Efficiency of Clathrates?

    NASA Astrophysics Data System (ADS)

    Yan, X.; Falmbigl, M.; Rogl, G.; Grytsiv, A.; Prokofiev, A.; Bauer, E.; Rogl, P.; Zehetbauer, M.; Paschen, S.

    2013-07-01

    High-pressure torsion (HPT), as a technique to produce severe plastic deformation, has been proven effective to improve the thermoelectric performance of skutterudites. In this report, we present microstructural and thermoelectric properties of the clathrate Ba8Cu3.5Ge41In1.5 processed by HPT. The sample was synthesized from high-purity elements, subsequently annealed, ball milled, and hot pressed, and finally subject to HPT. Compared with the ball-milled and hot-pressed sample, the HPT-processed sample has higher electrical resistivity and Seebeck coefficient, and lower thermal conductivity, electron concentration, and mobility, which is attributed to the reduced grain size and increased density of dislocations, point defects, and cracks. No essential improvement of the dimensionless thermoelectric figure of merit is observed in the investigated temperature range, questioning the universal versatility of this technique for improvement of thermoelectric materials.

  4. Fiber optic stress-independent helical torsion sensor.

    PubMed

    Fernandes, Luís A; Grenier, Jason R; Aitchison, J Stewart; Herman, Peter R

    2015-02-15

    Femtosecond laser-fabricated waveguides have been formed into helical paths throughout the cladding of single-mode optical fibers to demonstrate a strain-independent fiber torsion sensor. A comparison between a Bragg grating sensor and a Mach-Zehnder based on helical waveguides (HWs) showed a much weaker twist sensitivity of 1.5 pm/(rad/m) for the grating in contrast with a value of 261 pm/(rad/m) for the interferometer. The HW geometry provided an unambiguous determination of the rotational direction of the twist while facilitating a convenient and efficient means for optical coupling into the single-mode core of the fiber. The flexible three-dimensional writing by the femtosecond laser fabrication method enabled the direct inscription of compact and robust optical cladding devices without the need for combining or splicing multiple-fiber segments.

  5. Test of spatial isotropy using a cryogenic torsion pendulum

    NASA Technical Reports Server (NTRS)

    Phillips, Peter R.

    1987-01-01

    Motion of the earth through the cosmic neutrino background, or through certain kinds of vacuum states, produces a term of the form g(sigma) x v in the energy of an electron. To search for such a term, a cryogenic torsion pendulum carrying a transversely polarized magnet was used. Superconducting shields reduced magnetic torques. A sigma x v term would produce a sinusoidal oscillation of the pendulum with a period of one sidereal day. Such an oscillation was not detected, and a new limit of 8.5 x 10 to the -18th eV has been set for the splitting of the spin states of an electron at rest on the earth.

  6. Propagation and reflection of diffusionless torsional waves in a sphere

    NASA Astrophysics Data System (ADS)

    Maffei, S.; Jackson, A.

    2016-03-01

    We consider an inviscid and perfectly conducting fluid sphere in rapid rotation and permeated by a background magnetic field. Such a system admits normal modes in the form of torsional oscillations, namely azimuthal motions of cylinders coaxial with the rotation axis. We analyse this system for a particular background magnetic field that provides a new closed form normal mode solution. We derive Wentzel-Kramers-Brillouin-Jeffreys (WKBJ) approximations to the normal modes, and focus particularly on the reflections that take place on the rotation axis and at the equator. We propose a procedure to calculate the reflection coefficients and we discuss the analogy of our findings with well-known seismological results. Our analytical results are tested against numerical calculations and show good agreement.

  7. Torsion effects on a relativistic position-dependent mass system

    NASA Astrophysics Data System (ADS)

    Vitória, R. L. L.; Bakke, K.

    2016-12-01

    We analyse a relativistic scalar particle with a position-dependent mass in a spacetime with a space-like dislocation by showing that relativistic bound states solutions can be achieved. Further, we consider the presence of the Coulomb potential and analyse the relativistic position-dependent mass system subject to the Coulomb potential in the spacetime with a space-like dislocation. We also show that a new set of relativistic bound states solutions can be obtained, where there also exists the influence of torsion of the relativistic energy levels. Finally, we investigate an analogue of the Aharonov-Bohm effect for bound states in this position-dependent mass in a spacetime with a space-like dislocation.

  8. [Torsion of a liver cyst in a calf].

    PubMed

    Wieland, M; Blutke, A; Mann, S

    2014-01-01

    A 7-day-old male calf was presented because of an abdominal distension and a reduced feed intake. Sonographic examination showed a multi-chambered mass with anechoic content, separated by numerous hyperechoic septa in the ventral aspect of the abdomen. During diagnostic laparotomy, the cystic mass adhering to the diaphragmatic surface of the liver was determined to be a liver cyst with a 720°-torsion separating the cyst into two parts. A complete resection of the pedunculated cyst was achieved. The calf recovered completely and body-weight gain following surgery was typical for its age and breed. Histopathological examination of the cystic wall confirmed the diagnosis of a serosal liver cyst.

  9. Human ocular torsion during parabolic flights: an analysis with scleral search coil

    NASA Technical Reports Server (NTRS)

    Cheung, B. S.; Money, K.; Howard, I.; Kirienko, N.; Johnson, W.; Lackner, J.; Dizio, P.; Evanoff, J.

    1992-01-01

    Rotation of the eyes about the visual axis is known as ocular torsion. A lateral inclination (a "roll") of the head induces ocular torsion in the opposite direction, a response known as ocular counterrolling. For six subjects, we recorded the static (head still) and dynamic (head in oscillatory roll motion) ocular torsion in normal 1 g condition and also during the microgravity and hypergravity periods of parabolic flight, using the electromagnetic scleral search coil technique. With the head still, the direction and magnitude of torsion that occurred in response to microgravity and hypergravity differed substantially from one individual to another, but there was a significant difference in torsional magnitude between the microgravity and hypergravity periods, for all static head positions including the upright position. Under normal 1 g conditions, counterrolling compensated for about 16% of (voluntary) static head roll, while dynamic counterroll was much larger, up to 36% of head roll at 0.55 Hz. With increasing frequency of head oscillation between 0.33 Hz and 0.55 Hz, the gain of counterrolling increased and there was no change in the phase relationship. The gain of dynamic counterroll (in response to voluntary head rolling) was not significantly less in hypogravity, suggesting that on the ground at these frequencies the contribution of gravity and gravity receptors to this reflex is redundant: this reflex is probably driven by the semicircular canals. In some subjects, the torsional displacement in microgravity is accompanied by micro-torsional oscillatory motion.

  10. Instability of ocular torsion in zero gravity - Possible implications for space motion sickness

    NASA Technical Reports Server (NTRS)

    Diamond, Shirley G.; Markham, Charles H.; Money, Ken E.

    1990-01-01

    It is proposed that study of the eye torsion reflex and its behavior under novel gravitational states may possibly provide the basis for a long-sought test to predict space motion sickness (SMS). Measures of eye torsion such as ocular counterrolling and spontaneous eye torsion, were examined during hypo- and hypergravity in parabolic flight on the NASA KC-135 aircraft. Ten subjects, including two astronauts, one who had experienced SMS and one who had not, were ranked according to scores of torsional inability at 0 G and divided into two equal groups of high and low susceptibility to SMS. At 1.8 G the groups were significantly different in both the instability measure and the measure of torsional ability. No differences were detected in eye torsion in either 0 G or 1.8 G and none of the tests were significantly different in 1 G. Results suggest that tests of eye torsion on the KC-135 might differentiate those who would experience SMS from those who would not, although it is noted that this is not yet proven.

  11. Frequency-dependent solvent friction and torsional damping in liquid 1,2-difluoroethane

    NASA Astrophysics Data System (ADS)

    MacPhail, Richard A.; Monroe, Frances C.

    1991-04-01

    We have used Raman spectroscopy to study the torsional dynamics, rotational dynamics, and conformational solvation energy of liquid 1,2-difluoroethane. From the Raman intensities, we obtain Δ H(g-t) = -2.4±0.1 kcal/mol, indicating strong dipolar solvation of the gauche conformer. We analyze the Raman linewidths of the CCF bending bands to obtain the zero-frequency torsional damping coefficient or well friction for the gauche conformer, and from the linewidth of the torsion band we obtain the friction evaluated at the torsional frequency. The zero-frequency well friction shows deviations from hydrodynamic behavior reminiscent of those observed for barrier friction, whereas the high-frequency friction is considerably smaller in magnitude and independent of temperature and viscosity. The zero-frequency torsional friction correlates linearly with the rotational friction. It is argued that the small amplitude of the torsional fluctuations emphasizes the short distance, or high wavevector components of the solvent friction. Dielectric friction apparently does not contribute to the torsional friction at the observed frequencies.

  12. Dose-dependent protective effect of baicalin against testicular torsion-detorsion in rats.

    PubMed

    Fouad, A A; Qutub, H O; Jresat, I

    2017-02-01

    Testicular torsion/detorsion induces oxidative/nitrosative stress, inflammation and apoptosis of testicular tissues. Baicalin exerts antioxidant and anti-inflammatory properties. This study investigated the possible protective effect of baicalin against testicular torsion-detorsion injury in rats. Surgical testicular torsion was induced for 2 h, followed by detorsion which was continued for 24 h. Baicalin was administered in three different doses (25, 50 and 100 mg kg(-1) , by intraperitoneal injection). Each dose was given twice, the first 30 min before and the second 12 h after testicular detorsion. Baicalin, in a dose-dependent manner, decreased the torsion/detorsion-induced elevations of testicular malondialdehyde, nitric oxide, tumour necrosis factor-α, BCL2-associated X protein (Bax), cytosolic cytochrome c and caspase-3 and caspase-9 activities. Baicalin, dose dependently, attenuated the reductions of B-cell leucemia/lymphoma 2 (Bcl-2), and glutathione peroxidase and superoxide dismutase activities in testicular tissues resulted from torsion/detorsion. In addition, baicalin ameliorated the histopathological testicular tissue damage and reduced the expression of Fas ligand in rat testes exposed to torsion/detorsion in a dose-dependent manner. It was concluded that baicalin, dose dependently, ameliorated testicular injury induced by torsion/detorsion via its antioxidant, antinitrosative, anti-inflammatory and anti-apoptotic effects.

  13. Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequencing Effects

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Bonacuse, Peter J.

    2000-01-01

    Cumulative fatigue behavior of a wrought cobalt-base superalloy, Haynes 188 was investigated at 538 C under various single-step sequences of axial and torsional loading conditions. Initially, fully-reversed, axial and torsional fatigue tests were conducted under strain control at 538 C on thin-walled tubular specimens to establish baseline fatigue life relationships. Subsequently, four sequences (axial/axial, torsional/torsional, axial/torsional, and torsional/axial) of two load-level fatigue tests were conducted to characterize both the load-order (high/low) and load-type sequencing effects. For the two load-level tests, summations of life fractions and the remaining fatigue lives at the second load-level were computed by the Miner's Linear Damage Rule (LDR) and a nonlinear Damage Curve Approach (DCA). In general, for all four cases predictions by LDR were unconservative. Predictions by the DCA were within a factor of two of the experimentally observed fatigue lives for a majority of the cumulative axial and torsional fatigue tests.

  14. The predicted effect of aerodynamic detuning on coupled bending-torsion unstalled supersonic flutter

    NASA Technical Reports Server (NTRS)

    Hoyniak, D.; Fleeter, S.

    1986-01-01

    A mathematical model is developed to predict the enhanced coupled bending-torsion unstalled supersonic flutter stability due to alternate circumferential spacing aerodynamic detuning of a turbomachine rotor. The translational and torsional unsteady aerodynamic coefficients are developed in terms of influence coefficients, with the coupled bending-torsion stability analysis developed by considering the coupled equations of motion together with the unsteady aerodynamic loading. The effect of this aerodynamic detuning on coupled bending-torsion unstalled supersonic flutter as well as the verification of the modeling are then demonstrated by considering an unstable 12 bladed rotor, with Verdon's uniformly spaced Cascade B flow geometry as a baseline. However, with the elastic axis and center of gravity at 60 percent of the chord, this type of aerodynamic detuning has a minimal effect on stability. For both uniform and nonuniform circumferentially space rotors, a single degree of freedom torsion mode analysis was shown to be appropriate for values of the bending-torsion natural frequency ratio lower than 0.6 and higher 1.2. When the elastic axis and center of gravity are not coincident, the effect of detuning on cascade stability was found to be very sensitive to the location of the center of gravity with respect to the elastic axis. In addition, it was determined that when the center of gravity was forward of an elastic axis located at midchord, a single degree of freedom torsion model did not accurately predict cascade stability.

  15. Plastic Behavior and Fracture of Aluminum and Copper in Torsion Tests

    SciTech Connect

    Bressan, Jose Divo

    2007-04-07

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

  16. Carbon nanotube torsional springs for regenerative braking systems

    NASA Astrophysics Data System (ADS)

    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.

  17. Old torsion Balance Observations - too old for modern Exploration?

    NASA Astrophysics Data System (ADS)

    Götze, H.-J.

    2003-04-01

    Gravity gradiometry is a new gravity measurement technology that could fundamentally change the game of subsurface modelling and enhance geological interpretations: at fully inertial stabilized platforms they provide observed components of the E&{uml;o}tv&{uml;o}s tensor for 3D interpretations in mining and oil exploration and other fields of pure and applied geophysics. Although gravity gradiometry was among the first geophysical methods used successfully in applied Geophysics (E&{uml;o}tv&{uml;o}s torsion balance), the technology fell from favour in the 1930s. From this time measurements, done by torsion balances (Drehwaagen), are presented here which were observed to detect salt domes in the Northwest German basin. The data were digitized from old copies, then reprocessed and recalculated to draw Bouguer anomaly maps. However, the second derivatives of the gravity potential provide also independent data which can be used to constrain forward modelling. 3D modelling of Vxz, Vyz and other components of the E&{uml;o}tv&{uml;o}s tensor provide better insight into the geometry of the salt dome structure than modelling of the Bouguer gravity field. In addition to this first example results from gravity data processing by applying curvature techniques and again 3D forward modelling of second derivatives of the potential of density domains in the uppermost crust in the area of the Dead Sea Transform (Jordan) is presented here. The 3D modelling is conducted by the program package IGMAS which supply possibilities to calculate potential, gravity, its components and the Eötvös tensor components. Based on results so far one can conclude that the knowledge of the "second derivatives of the potential" could fundamentally change the role of gravity field measurements in the process of underground investigations not only for resource exploration but for investigations along large faults systems.

  18. Anisotropy of torsional rigidity of sheet polymer composite materials

    NASA Astrophysics Data System (ADS)

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

    1999-05-01

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

  19. Torsional elasticity and energetics of F1-ATPase.

    PubMed

    Czub, Jacek; Grubmüller, Helmut

    2011-05-03

    F(o)F(1)-ATPase is a rotary motor protein synthesizing ATP from ADP driven by a cross-membrane proton gradient. The proton flow through the membrane-embedded F(o) generates the rotary torque that drives the rotation of the asymmetric shaft of F(1). Mechanical energy of the rotating shaft is used by the F(1) catalytic subunit to synthesize ATP. It was suggested that elastic power transmission with transient storage of energy in some compliant part of the shaft is required for the observed high turnover rate. We used atomistic simulations to study the spatial distribution and structural determinants of the F(1) torsional elasticity at the molecular level and to comprehensively characterize the elastic properties of F(1)-ATPase. Our fluctuation analysis revealed an unexpected heterogeneity of the F(1) shaft elasticity. Further, we found that the measured overall torsional moduli of the shaft arise from two distinct contributions, the intrinsic elasticity and the effective potential imposed on the shaft by the catalytic subunit. Separation of these two contributions provided a quantitative description of the coupling between the rotor and the catalytic subunit. This description enabled us to propose a minimal quantitative model of the F(1) energetics along the rotary degrees of freedom near the resting state observed in the crystal structures. As opposed to the usually employed models where the motor mechanical progression is described by a single angular variable, our multidimensional treatment incorporates the spatially inhomogeneous nature of the shaft and its interactions with the stator and offers new insight into the mechanoenzymatics of F(1)-ATPase.

  20. Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    We obtain quantum geometries on a vacuum created pair of a (DDbar)3-brane, at a Big Bang singularity, by a local two form on a D4-brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DDbar)-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D4-brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.

  1. Technology development for the LISA using the UF Torsion Pendulu

    NASA Astrophysics Data System (ADS)

    Conklin, John W.; Chilton, Andrew; Olatunde, Taiwo; Apple, Stephen; Ciani, Giacomo; Mueller, Guido

    2015-08-01

    Space-based gravitational wave observatories like LISA measure picometer changes in the distances between free falling test masses separated by millions of kilometers caused by gravitational waves. A test mass and its associated sensing, actuation, charge control and caging subsystems are referred to as a gravitational reference sensor (GRS). LISA will observe gravitational wave sources ranging from super-massive black hole mergers to compact galactic binaries in the millihertz region, and LISA science has consistently been ranked in the top two for future large space missions in the last two NASA astrophysics decadal reviews. With the 2015 launch of LISA Pathfinder (LPF) and the expected detection of gravitational waves by aLIGO and/or Pulsar Timing Arrays within in the next several years, this can arguably be called the decade of gravitational waves. Following a successful demonstration of the baseline LISA GRS by LPF, the measurement principle will be carried forward, but improvements in several GRS components are possible over the next ten years that will lead to cost savings and potential noise reductions. The UF LISA group has constructed the UF Torsion Pendulum to increase U.S. competency in this critical area and to have a facility where new technologies can be developed and evaluated. This experimental facility is based on the design of a similar facility at the University of Trento, and consists of a vacuum enclosed torsion pendulum that suspends mock-ups of the LISA test masses, surrounded by electrode housings. This presentation will describe this facility, focusing on its mechanical design, capacitive sensing and electrostatic actuation systems, and overall acceleration noise performance

  2. Lorentz violation from torsion trace and non-minimal coupling in radio galactic dynamos

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2011-12-01

    Earlier Kostelecky et al. [A. Kostelecky, N. Russell, and J. Tasson, Phys Rev Lett 100, 111102 (2008).PRLTAO0031-900710.1103/PhysRevLett.100.111102] have obtained torsion bounds from Lorentz violation, where torsion components are taken from the axial part of torsion. In this brief report it is shown that more stringent bounds may be obtained by using nearly minimal magnetogenesis torsion trace instead of the minimal coupling between photons and axial torsion used by Kostelecky and his group. Just for comparison, in Kostelecky et al., the most stringent limit is estimated to be 10-31GeV while here one obtains 10-33GeV. This estimate is obtained by constraining the torsion to galactic astronomy data. From the point of view of magnetogenesis, an interesting physical consequence is that dynamo action is obtained when the torsion trace background is negative, while the magnetic field energy decays when torsion is positive. Polarization of radio-galaxies can be used to obtain an even more stringent limit of T˜1.7×10-46GeV to Lorentz violation. Using WMAP, Kostelecky and Mewes [A. Kostelecky and M. Mewes, Astrophys. J. 689, L1 (2008)ASJOAB0004-637X10.1086/595815] have found limits of the order of 10-43GeV. These results are obtained by making use of flat torsion modes [L. Garcia de Andrade, Phys Lett B 696, 1 (2011)], but may easily be extended to Riemann-Cartan spacetime.

  3. Spin precession of slow neutrons in Einstein-Cartan gravity with torsion, chameleon, and magnetic field

    NASA Astrophysics Data System (ADS)

    Ivanov, A. N.; Wellenzohn, M.

    2016-02-01

    We analyze a spin precession of slow neutrons in the Einstein-Cartan gravity with torsion, chameleon and magnetic field. For the derivation of the Heisenberg equation of motion of the neutron spin we use the effective low-energy potential, derived by Ivanov and Wellenzohn [Phys. Rev. D 92, 125004 (2015)] for slow neutrons, coupled to gravitational, chameleon, and torsion fields to order 1 /m , where m is the neutron mass. In addition to these low-energy interactions we switch on the interaction of slow neutrons with a magnetic field. We show that to linear order approximation with respect to gravitational, chameleon, and torsion fields the Dirac Hamilton operator for fermions (neutrons), moving in spacetimes created by rotating coordinate systems, contains the anti-Hermitian operators of torsion-fermion (neutron) interactions, caused by torsion scalar and tensor space-space-time and time-space-space degrees of freedom. Such anti-Hermitian operators violate C P and T invariance. In the low-energy approximation the C P and T violating torsion-fermion (neutron) interactions appear only to order O (1 /m ). One may assume that in the rotating Universe and galaxies the obtained anti-Hermitian torsion-fermion interactions might be an origin of (i) violation of C P and T invariance in the Universe and (ii) of baryon asymmetry. We show that anti-Hermitian torsion-fermion interactions of relativistic fermions, violating C P and T invariance, (i) cannot be removed by nonunitary transformations of the Dirac fermion wave functions and (ii) are conformal invariant. According to general requirements of conformal invariance of massive particle theories in gravitational fields [see R. H. Dicke, Phys. Rev. 125, 2163 (1962) and A. J. Silenko, Phys. Rev. D 91, 065012 (2015)], conformal invariance of anti-Hermitian torsion-fermion interactions is valid only if the fermion mass is changed by a conformal factor.

  4. The effect of DNA supercoiling on nucleosome structure and stability.

    PubMed

    Elbel, Tabea; Langowski, Jörg

    2015-02-18

    Nucleosomes have to open to allow access to DNA in transcription, replication, and DNA damage repair. Changes in DNA torsional strain (e.g. during transcription elongation) influence the accessibility of nucleosomal DNA. Here we investigated the effect of DNA supercoiling-induced torsional strain on nucleosome structure and stability by scanning force microscopy (SFM) and fluorescence correlation spectroscopy (FCS). Nucleosomes were reconstituted onto 2.7 kb DNA plasmids with varying superhelical densities. The SFM results show a clear dependence of the amount of DNA wrapped around the nucleosome core on the strength and type of supercoiling. Negative supercoiling led to smaller nucleosome opening angles as compared to relaxed or positively supercoiled DNA. FCS experiments show that nucleosomes reconstituted on negatively superhelical DNA are more resistant to salt-induced destabilization, as seen by reduced H2A-H2B dimer eviction from the nucleosome. Our results show that changes in DNA topology, e.g. during transcription elongation, affect the accessibility of nucleosomal DNA.

  5. The effect of DNA supercoiling on nucleosome structure and stability

    NASA Astrophysics Data System (ADS)

    Elbel, Tabea; Langowski, Jörg

    2015-02-01

    Nucleosomes have to open to allow access to DNA in transcription, replication, and DNA damage repair. Changes in DNA torsional strain (e.g. during transcription elongation) influence the accessibility of nucleosomal DNA. Here we investigated the effect of DNA supercoiling-induced torsional strain on nucleosome structure and stability by scanning force microscopy (SFM) and fluorescence correlation spectroscopy (FCS). Nucleosomes were reconstituted onto 2.7 kb DNA plasmids with varying superhelical densities. The SFM results show a clear dependence of the amount of DNA wrapped around the nucleosome core on the strength and type of supercoiling. Negative supercoiling led to smaller nucleosome opening angles as compared to relaxed or positively supercoiled DNA. FCS experiments show that nucleosomes reconstituted on negatively superhelical DNA are more resistant to salt-induced destabilization, as seen by reduced H2A-H2B dimer eviction from the nucleosome. Our results show that changes in DNA topology, e.g. during transcription elongation, affect the accessibility of nucleosomal DNA.

  6. Determining the shear fracture properties of HIP joints of reduced-activation ferritic/martensitic steel by a torsion test

    NASA Astrophysics Data System (ADS)

    Nozawa, Takashi; Noh, Sanghoon; Tanigawa, Hiroyasu

    2012-08-01

    Hot isostatic pressing (HIP) is a key technology used to fabricate a first wall with cooling channels for the fusion blanket system utilizing a reduced-activation ferritic/martensitic steel. To qualify the HIPped components, small specimen test techniques are beneficial not only to evaluate the thin-wall cooling channels containing the HIP joint but also to use in neutron irradiation studies. This study aims to develop the torsion test method with special emphasis on providing a reasonable and comprehensive method to determine interfacial shear properties of HIP joints during the torsional fracture process. Torsion test results identified that the torsion process shows yield of the base metal followed by non-elastic deformation due to work hardening of the base metal. By considering this work hardening issue, we propose a reasonable and realistic solution to determine the torsional yield shear stress and the ultimate torsional shear strength of the HIPped interface. Finally, a representative torsion fracture process was identified.

  7. Nonlinear equations of motion for elastic bending and torsion of isotropic rotor blades with piezoceramic actuation

    NASA Astrophysics Data System (ADS)

    Thakkar, Dipali; Ganguli, Ranjan

    2003-10-01

    Nonlinear equations of motion for elastic bending and torsion of isotropic rotor blades with surface bonded piezoceramic actuators are derived using Hamilton's principle. The equations are then solved using finite element discretization in the spatial and time domain. The effect of piezoceramic actuation is investigated for bending and torsion response of a rotating beam. It is found that the centrifugal stiffening effect reduces the tip transverse bending deflection and elastic twist as the rotation speed increases. However, the effect of rotation speed on the tip elastic twist is less pronounced. The importance of nonlinear terms for accurate prediction of torsion response is also shown.

  8. A TORSIONAL ALFVEN WAVE EMBEDDED WITHIN A SMALL MAGNETIC FLUX ROPE IN THE SOLAR WIND

    SciTech Connect

    Gosling, J. T.; Teh, W.-L.; Eriksson, S.

    2010-08-10

    We describe and use novel techniques to analyze a striking and distinct solar wind event observed by two spacecraft. We show that the event is consistent with an interpretation as a torsional Alfven wave embedded within a small, nearly radially aligned, magnetic flux rope of total width {approx}10{sup 6} km. It seems likely that the torsional wave was generated by distortions produced within a pre-existing flux rope that erupted from the Sun. Our examination of many events previously identified as flux ropes in the solar wind indicates that torsional Alfven waves are extremely rare in such events.

  9. An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy

    NASA Technical Reports Server (NTRS)

    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

  10. Use of optical coherence topography for objective assessment of fundus torsion.

    PubMed

    Sophocleous, Sophocles

    2017-02-23

    Objective assessment of fundus torsion is currently performed with indirect ophthalmoscopy or fundus photography. Using the infrared image of the macular scan of the optical coherence tomography one can assess the presence and amount of fundus torsion. In addition, the line scan through the fovea can be used as a reference to confirm the position of the foveal pit in relation to the optic nerve head. Two cases are used to demonstrate how to assess fundus torsion with the use of the optical coherence tomography.

  11. Unilateral uterine torsion secondary to an inflammatory endometrial polyp in the bitch.

    PubMed

    Chambers, Ba; Laksito, Ma; Long, F; Yates, Gd

    2011-10-01

    A 9-year-old bitch was presented because of lethargy and abdominal distension. Abdominal ultrasound revealed an enlarged, fluid-filled uterus and associated mass. Subsequent exploratory laparotomy revealed unilateral uterine torsion involving the mass. Recovery following ovariohysterectomy was uneventful and the histopathological diagnosis was of a benign endometrial inflammatory polyp. Reports of uterine torsion in the English-language literature are reviewed to identify factors associated with the incidence of uterine torsion. The aetiology of the cystic endometrial hyperplasia/pyometra complex and its possible role in the development of inflammatory polypoid lesions in the bitch is also discussed.

  12. 11-cis retinal torsion: A QTAIM and stress tensor analysis of the S1 excited state

    NASA Astrophysics Data System (ADS)

    Maza, Julio R.; Jenkins, Samantha; Kirk, Steven R.

    2016-05-01

    We investigate torsion about the C11-C12 bond mid-point for the S1 state of 11-cis retinal, using a QTAIM and stress tensor analysis. The QTAIM and stress tensor responses to a torsion ±α increase at a faster rate for the preferred direction of torsion though the CI seam. A QTAIM and stress tensor vector-based analysis provides an alternative way of characterising the asymmetry of the S1 potential energy surface. In the vicinity of the CI seam the ellipticity ε attained minimum values. The application of this analysis to molecular rotary motors is briefly discussed.

  13. Time-resolved torsional relaxation of spider draglines by an optical technique.

    PubMed

    Emile, O; Le Floch, A; Vollrath, F

    2007-04-20

    The sensitivity of the torsional pendulum demonstrates the self-shape-memory effect in different types of spider draglines. Here we report the time-resolved noncovalent bonds recovery in the protein structure. The torsional dynamics of such multilevel structure governed by reversible interactions are described in the frame of a nested model. Measurement of three different relaxation times confirms the existence of three energy storage levels in such two protein spidroin systems. Torsion opens the way to further investigations towards unraveling the tiny torque effects in biological molecules.

  14. Time-Resolved Torsional Relaxation of Spider Draglines by an Optical Technique

    NASA Astrophysics Data System (ADS)

    Emile, O.; Floch, A. Le; Vollrath, F.

    2007-04-01

    The sensitivity of the torsional pendulum demonstrates the self-shape-memory effect in different types of spider draglines. Here we report the time-resolved noncovalent bonds recovery in the protein structure. The torsional dynamics of such multilevel structure governed by reversible interactions are described in the frame of a nested model. Measurement of three different relaxation times confirms the existence of three energy storage levels in such two protein spidroin systems. Torsion opens the way to further investigations towards unraveling the tiny torque effects in biological molecules.

  15. Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review.

    PubMed

    Budinski, Vedran; Donlagic, Denis

    2017-02-23

    Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.Invited Paper.

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

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1978-01-01

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

  17. Appearance of singularities of optical fields under torsion of crystals containing threefold symmetry axes.

    PubMed

    Skab, Ihor; Vasylkiv, Yurij; Zapeka, Bohdan; Savaryn, Viktoriya; Vlokh, Rostyslav

    2011-07-01

    We present an analysis of the effect of torsion stresses on the spatial distribution of optical birefringence in crystals of different point symmetry groups. The symmetry requirements needed so that the optical beam carries dislocations of the phase front are evaluated for the case when the crystals are twisted and the beam closely corresponds to a plane wave. It is shown that the torsion stresses can produce screw-edge, pure screw, or pure edge dislocations of the phase front in the crystals belonging to cubic and trigonal systems. The conditions for appearance of canonical and noncanonical vortices in the conditions of crystal torsion are analyzed.

  18. Helicopter trim with flap-lag-torsion and stall by an optimized controller

    NASA Technical Reports Server (NTRS)

    Peters, David A.; Chouchane, Mnaouar; Fulton, Mark

    1990-01-01

    An autopilot is applied to helicopter rotor flap-lag-torsion equations to obtain the control settings for a trimmed flight condition. The rotor aerodynamic description includes a stage-space dynamic stall model for lift and for pitching moments. Thus, the rotor is trimmed for flight conditions in which significant stall and torsional deformations are present. The autopilot is extended to Q-bladed rotors by a series of time-delay terms. As a result, the optimum gains and time constants depend upon the number of blades as well as upon the torsional stiffness.

  19. Testing rig for low cycle fatigue tests in combined bending and torsion

    NASA Astrophysics Data System (ADS)

    Caligiana, Gianni; Curioni, Sergio

    1992-07-01

    In order to simulate, on samples, the fatigue behavior of notched or grooved shafts used in industrial plants, a biaxal testing equipment, to transform the alternate motion of a conventional testing machine into combined torsion and bending cyclic loadings, was devised and realized. Several different amplitude ratios between torsion and bending can be obtained beyond pure torsion and pure bending. Design choices, modeling, numerical simulations and experimental verifications performed for the testing apparatus are reported. Influence of misalignment and manufacturing imperfections on the behavior of the equipment are considered.

  20. Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review †

    PubMed Central

    Budinski, Vedran; Donlagic, Denis

    2017-01-01

    Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation. PMID:28241510

  1. Torsional vibrational modes of tryptophan studied by terahertz time-domain spectroscopy.

    PubMed

    Yu, B; Zeng, F; Yang, Y; Xing, Q; Chechin, A; Xin, X; Zeylikovich, I; Alfano, R R

    2004-03-01

    The low-frequency torsional modes, index of refraction, and absorption of a tryptophan film and pressed powders from 0.2 to 2.0 THz (6.6-66 cm(-1)) were measured by terahertz time-domain spectroscopy at room temperature. It was found that there were two dominated torsional vibrational modes at around 1.435 and 1.842 THz. The associated relaxation lifetimes ( approximately 1 ps) for these modes of the tryptophan molecule were measured. Using a density-functional calculation, the origins of the observed torsional vibrations were assigned to the chain and ring of the tryptophan molecule.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    We present an improved version of the MSTor program package, which calculates partition functions and thermodynamic functions of complex molecules involving multiple torsions; the method is based on either a coupled torsional potential or an uncoupled torsional potential. The program can also carry out calculations in the multiple-structure local harmonic approximation. The program package also includes seven utility codes that can be used as stand-alone programs to calculate reduced moment of inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes for torsional subdomains defined by Voronoi tessellation of the conformational subspace, to generate template input files for the MSTor calculation and Voronoi calculation, and to calculate one-dimensional torsional partition functions using the torsional eigenvalue summation method. Restrictions: There is no limit on the number of torsions that can be included in either the Voronoi calculation or the full MS-T calculation. In practice, the range of problems that can be addressed with the present method consists of all multitorsional problems for which one can afford to calculate all the conformational structures and their frequencies. Unusual features: The method can be applied to transition states as well as stable molecules. The program package also includes the hull program for the calculation of Voronoi volumes, the symmetry program for determining point group symmetry of a molecule, and seven utility codes that can be used as stand-alone programs to calculate reduced moment-of-inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes of the torsional subdomains defined by Voronoi tessellation of the conformational subspace, to generate template input files, and to calculate one-dimensional torsional

  3. Brownian dynamics simulation of DNA condensation.

    PubMed Central

    Sottas, P E; Larquet, E; Stasiak, A; Dubochet, J

    1999-01-01

    DNA condensation observed in vitro with the addition of polyvalent counterions is due to intermolecular attractive forces. We introduce a quantitative model of these forces in a Brownian dynamics simulation in addition to a standard mean-field Poisson-Boltzmann repulsion. The comparison of a theoretical value of the effective diameter calculated from the second virial coefficient in cylindrical geometry with some experimental results allows a quantitative evaluation of the one-parameter attractive potential. We show afterward that with a sufficient concentration of divalent salt (typically approximately 20 mM MgCl(2)), supercoiled DNA adopts a collapsed form where opposing segments of interwound regions present zones of lateral contact. However, under the same conditions the same plasmid without torsional stress does not collapse. The condensed molecules present coexisting open and collapsed plectonemic regions. Furthermore, simulations show that circular DNA in 50% methanol solutions with 20 mM MgCl(2) aggregates without the requirement of torsional energy. This confirms known experimental results. Finally, a simulated DNA molecule confined in a box of variable size also presents some local collapsed zones in 20 mM MgCl(2) above a critical concentration of the DNA. Conformational entropy reduction obtained either by supercoiling or by confinement seems thus to play a crucial role in all forms of condensation of DNA. PMID:10512808

  4. Importance of DNA stiffness in protein-DNA binding specificity

    NASA Astrophysics Data System (ADS)

    Hogan, M. E.; Austin, R. H.

    1987-09-01

    From the first high-resolution structure of a repressor bound specifically to its DNA recognition sequence1 it has been shown that the phage 434 repressor protein binds as a dimer to the helix. Tight, local interactions are made at the ends of the binding site, causing the central four base pairs (bp) to become bent and overtwisted. The centre of the operator is not in contact with protein but repressor binding affinity can be reduced at least 50-fold in response to a sequence change there2. This observation might be explained should the structure of the intervening DNA segment vary with its sequence, or if DNA at the centre of the operator resists the torsional and bending deformation necessary for complex formation in a sequence dependent fashion. We have considered the second hypothesis by demonstrating that DNA stiffness is sequence dependent. A method is formulated for calculating the stiffness of any particular DNA sequence, and we show that this predicted relationship between sequence and stiffness can explain the repressor binding data in a quantitative manner. We propose that the elastic properties of DNA may be of general importance to an understanding of protein-DNA binding specificity.

  5. Vertebral artery dolicoectasia with brainstem compression: role of microvascular decompression in relieving pyramidal weakness.

    PubMed

    Sadashiva, Nishanth; Shukla, Dhaval; Bhat, Dhananjaya I; Devi, Bhagavatula Indira

    2016-04-01

    Vertebral artery dolicoectasia (VAD) can cause brainstem compression and dysfunction. Reports of pyramidal tract involvement by brainstem compression and the surgical benefits and its long-term results are sparsely reported. We hereby report three cases of medullary compression by VAD causing pyramidal weakness. Two patients with bilateral compression with quadriparesis did not want surgical treatment and were still disabled at 58 months and 50 months of follow-up, respectively. One patient with unilateral medullary compression with hemiparesis underwent microvascular decompression using Teflon sling retraction. This patient was relieved of symptoms and is asymptomatic at 14-month follow-up. This report emphasizes the need of surgical decompression in cases of brainstem compression by VAD with caution about appropriate case selection.

  6. Zeolites relieves inhibitory stress from high concentrations of long chain fatty acids.

    PubMed

    Nordell, Erik; Hansson, Anna B; Karlsson, Martin

    2013-12-01

    Protein and fat rich slaughterhouse waste is a very attractive waste stream for the production of biogas because of the high biochemical methane potential of the substrate. The material has however some drawbacks as the sole material for biogas production due to the production of several process disturbing metabolites such as ammonia, sulfides and long chain fatty acids. We can in this work present results that show that zeolites have the potential to relieve inhibitory stress from the presence of long chain fatty acids. Moreover, the results strongly indicate that it is mainly acetic acid consumers that are most negatively affected by long chain fatty acids and that the mechanism of stress relief is an adsorption of long chain fatty acids to the zeolites. In addition to this, it is shown that the effect is immediate and that only a small amount of zeolites is necessary to cancel the inhibitory effect of long chain fatty acids.

  7. Frustration relieved ferrimagnetism in novel A- and B-site-ordered quadruple perovskite.

    PubMed

    Chen, Wei-tin; Mizumaki, Masaichiro; Saito, Takashi; Shimakawa, Yuichi

    2013-07-28

    A novel A- and B-site-ordered quadruple perovskite CaCu3Fe2Sb2O12 was obtained and it shows ferrimagnetism below about 170 K. The B-site Fe spin sublattice adapts a tetrahedral framework in a cubic structure and the Fe(3+)-Fe(3+) antiferromagnetic interaction can result in a geometrical spin frustration as seen in a simple perovskite Ca2FeSbO6. With the introduction of Cu(2+) into the A' site, the antiferromagnetic spin frustration is relieved by the strong Cu(2+)-Fe(3+) interaction, and a ferrimagnetic ordering appears at a much higher temperature than the spin-glass transition temperature.

  8. A block to pre-prepared movement in gait freezing, relieved by pedunculopontine nucleus stimulation.

    PubMed

    Thevathasan, Wesley; Pogosyan, Alek; Hyam, Jonathan A; Jenkinson, Ned; Bogdanovic, Marko; Coyne, Terry J; Silburn, Peter A; Aziz, Tipu Z; Brown, Peter

    2011-07-01

    Gait freezing and postural instability are disabling features of Parkinsonian disorders, treatable with pedunculopontine nucleus stimulation. Both features are considered deficits of proximal and axial musculature, innervated predominantly by reticulospinal pathways and tend to manifest when gait and posture require adjustment. Adjustments to gait and posture are amenable to pre-preparation and rapid triggered release. Experimentally, such accelerated release can be elicited by loud auditory stimuli--a phenomenon known as 'StartReact'. We observed StartReact in healthy and Parkinsonian controls. However, StartReact was absent in Parkinsonian patients with severe gait freezing and postural instability. Pedunculopontine nucleus stimulation restored StartReact proximally and proximal reaction times to loud stimuli correlated with gait and postural disturbance. These findings suggest a relative block to triggered, pre-prepared movement in gait freezing and postural instability, relieved by pedunculopontine nucleus stimulation.

  9. Fermions in Gödel-type background space-times with torsion and the Landau quantization

    NASA Astrophysics Data System (ADS)

    Garcia, G. Q.; de S. Oliveira, J. R.; Bakke, K.; Furtado, C.

    2017-03-01

    In this paper, we analyze Dirac fermions in Gödel-type background space-times with torsion. We also consider the Gödel-type space-times embedded in a topological defect background. We show that relativistic bound states solutions to the Dirac equation can be obtained by dealing with three cases of the Gödel-type solutions with torsion, where a cosmic string passes through these three cases of the space-time. We obtain the relativistic energy levels for all cases of the Gödel-type solutions with torsion with a cosmic string, where we show that there exists an analogy with the Landau levels for Dirac particles. We also show that the presence of torsion in the space-time yields new contributions to the relativistic spectrum of energies and that the presence of the topological defect modifies the degeneracy of the relativistic energy levels.

  10. Optimal design of a magneto-rheological brake absorber for torsional vibration control

    NASA Astrophysics Data System (ADS)

    Nguyen, Q. H.; Choi, S. B.

    2012-02-01

    This research presents an optimal design of a magneto-rheological (MR) brake absorber for torsional vibration control of a rotating shaft. Firstly, the configuration of an MR brake absorber for torsional vibration control of a rotating shaft system is proposed. Then, the braking torque of the MR brake is derived based on the Bingham plastic model of the MR fluid. By assuming that the behaviour of the MR brake absorber is similar to that of a dry friction torsional damper, the optimal braking torque to control the torsional vibration is determined and validated by simulation. The optimal design problem of the MR brake absorber is then developed and a procedure to solve the optimal problem is proposed. Based on the proposed optimal design procedure, the optimal design of a specific rotating shaft system is performed. Vibration control performance of the shaft system employing the optimized MR brake absorber is then investigated through simulation and discussion on the results is given.

  11. External tibial torsion and the effectiveness of the solid ankle-foot orthoses.

    PubMed

    Vankoski, S J; Michaud, S; Dias, L

    2000-01-01

    The aims of this study were to determine the influence of external tibial torsion on the effectiveness of the ankle-foot orthoses (AFO) in children with lumbosacral myelomeningocele. Forty patients with normal tibial rotation and 18 patients with excessive external tibial torsion were evaluated with three-dimensional gait analysis at their comfortable walking speed. The group with normal tibial rotation showed significantly greater knee extension and lower mean extension moment compared with the group with external tibial torsion (p < 0.05). The posteriorly and laterally deviated ground-reaction force relative to the knee-flexion axis compromises the ability of this force to facilitate knee extension. Patients with torsional magnitudes >20 degrees demand close inspection as candidates for derotation osteotomy. The AFO will continue to stabilize the ankle-foot complex, but improved knee motion, knee-extensor activity, and ultimately walking efficiency may be compromised.

  12. Microstructure evolution in solution treated Ti15Mo alloy processed by high pressure torsion

    SciTech Connect

    Janeček, Miloš; Čížek, Jakub; Stráský, Josef; Václavová, Kristína; Hruška, Petr; Polyakova, Veronika; Gatina, Svetlana; Semenova, Irina

    2014-12-15

    Microstructure evolution and mechanical properties of ultra-fine grained Ti15Mo alloy processed by high pressure torsion were investigated. High pressure torsion straining resulted in strong grain refinement as-observed by transmission electron microscopy. Microhardness and light microscopy showed two distinct regions — (i) a central region with radial material flow and low microhardness (340 HV) and (ii) a peripheral region with rotational material flow and high microhardness (430 HV). Positron annihilation spectroscopy showed that the only detectable defects in the material are dislocations, whose density increases with the radial distance and the number of high pressure torsion revolutions. The local chemical environment around defects does not differ significantly from the average composition. - Highlights: • Beta-Ti alloy Ti15Mo was processed by high pressure torsion (HPT). • Lateral inhomogeneity of the microstructure and microhardness was found. • Dislocations are the only lattice defects detectable by positron annihilation. • Molybdenum is not preferentially segregated along dislocation cores.

  13. Microwave Spectroscopy of Trans-Ethyl Methyl Ether in the Torsionally Excited State 3

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kaori; Murata, Keigo; Tsunekawa, Shozo; Ohashi, Nobukimi

    2010-06-01

    The trans-ethyl methyl ether molecule (CH_3CH_2OCH_3) has two methyl group internal rotors which are equivalent to the two vibrational motions, ν28 and ν29. There is another low-lying torsional motion which is a skeltal torsion (ν30) and does not cause splitting. The microwave spectra of the trans-ethyl methyl ether molecule in the ν28 = 1, ν29 = 1, and ν30 = 1 have been studied and interactions between these states were discussed. In this paper we report results on the ν30 = 2, and 3 state. The analysis based on Hougen's tunneling matrix formulation considering two methyl groups are used. We try to interpret tunneling parameters obtained in the present analysis quantitatively from the viewpoint of torsion-torsion interaction.

  14. Raman spectra of gases. XVI - Torsional transitions in ethanol and ethanethiol

    NASA Technical Reports Server (NTRS)

    Durig, J. R.; Bucy, W. E.; Wurrey, C. J.; Carreira, L. A.

    1975-01-01

    The Raman spectra of gaseous ethanol and ethanethiol have been investigated. Thiol torsional fundamentals for the gauche conformer of EtSH and EtSD have been observed and the asymmetric potential function for this vibration has been calculated. Methyl torsional transitions and overtones have also been observed for both of these molecules. Barriers to internal rotation for the methyl top are calculated to be 3.77 and 3.84 kcal/mol for the EtSH and EtSD compounds, respectively. Hydroxyl torsional fundamentals were observed at 207 and 170 per cm in the EtOH and EtOD spectra, respectively. Overtones of the methyl torsion in both molecules yield a barrier to internal rotation of 3.62 kcal/mol for the gauche conformer.

  15. Some aspects of Holst and Nieh-Yan terms in general relativity with torsion

    NASA Astrophysics Data System (ADS)

    Banerjee, Kinjal

    2010-07-01

    We explore the relation of the Holst term with the Nieh-Yan term in terms of metric variables. We show that the Holst term indeed affects the classical equations of motion in the presence of matter with spin. Therefore, the correct term to add to the Einstein-Hilbert action such that the equations of motion are not affected is the Nieh-Yan term. We then calculate the torsion charge due to this term in the context of a perfect fluid sphere with torsion and show that it vanishes once a horizon is formed but not otherwise. We also show that on adding torsion to general relativity Einstein's equations are no longer holographic in torsion although they continue to be so for the metric.

  16. Adnexal Incarceration in a Posterior Pelvic Peritoneal Defect Mimics Ovarian Torsion.

    PubMed

    Jackson, Amanda M; Hope, Erica R; Phippen, Neil T

    2015-01-01

    Surgery for suspected ovarian torsion sometimes reveals unexpected sources of pelvic pain, such as internal hernias, adhesions, or anatomic defects. A 23-year-old nulligravida with Alagille syndrome was taken to the operating room with suspected ovarian torsion. Intraoperatively, the right adnexa bulged out of a right-sided, posterior peritoneal cleft that incarcerated most of the enlarged ovary. No ovarian torsion was identified. The left adnexa appeared to be normal; however, it dwelled within a left-sided posterior peritoneal cleft. The bilateral posterior peritoneal defects that housed the adnexa were likely of congenital etiology. Although adnexal incarceration is a rare finding at surgery for suspected ovarian torsion, it should be part of the differential diagnosis when evaluating acute pelvic pain.

  17. Electrically, chemically, and photonically powered torsional and tensile actuation of hybrid carbon nanotube yarn muscles.

    PubMed

    Lima, Márcio D; Li, Na; Jung de Andrade, Mônica; Fang, Shaoli; Oh, Jiyoung; Spinks, Geoffrey M; Kozlov, Mikhail E; Haines, Carter S; Suh, Dongseok; Foroughi, Javad; Kim, Seon Jeong; Chen, Yongsheng; Ware, Taylor; Shin, Min Kyoon; Machado, Leonardo D; Fonseca, Alexandre F; Madden, John D W; Voit, Walter E; Galvão, Douglas S; Baughman, Ray H

    2012-11-16

    Artificial muscles are of practical interest, but few types have been commercially exploited. Typical problems include slow response, low strain and force generation, short cycle life, use of electrolytes, and low energy efficiency. We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. Electrical, chemical, or photonic excitation of hybrid yarns changes guest dimensions and generates torsional rotation and contraction of the yarn host. Demonstrations include torsional motors, contractile muscles, and sensors that capture the energy of the sensing process to mechanically actuate.

  18. An improved torsion pendulum based on image processing for single fibers

    NASA Astrophysics Data System (ADS)

    Yu, Longteng; Liu, Dabiao; Peng, Kai; He, Yuming

    2016-07-01

    An improved torsion pendulum technique based on image processing is developed, which allows the measurement of the torsional oscillation of individual fibers. The torsion pendulum is composed of a length of fiber specimen and a ring-shaped mass attached to one of its ends. The oscillation motion of the mass is recorded with a video camera overhead. An image processing method is developed to accurately calculate the twist angle of single fibers in the torsion pendulum. All images are firstly converted into matrices and then the edge detection is applied to calculate the twist angle at corresponding time to obtain the angle-time relation. The oscillation frequency is determined by the fast Fourier transform (FFT) method. By applying this technique, we have performed tests on four types of fibers, namely T300 carbon fiber, copper, silver and tungsten wires. The longitudinal shear modulus measured for each type of these fibers is presented.

  19. Transformation of Hume-Rothery phases under the action of high pressure torsion

    NASA Astrophysics Data System (ADS)

    Straumal, B. B.; Kilmametov, A. R.; Kucheev, Yu. O.; Kolesnikova, K. I.; Korneva, A.; Zieba, P.; Baretzky, B.

    2014-11-01

    It has been revealed experimentally that high-pressure torsion induces phase transformations of certain Hume-Rothery phases (electron compounds) to others. High-pressure torsion induces the ξ → δ + ɛ reaction in copper-tin alloys with the appearance of the δ + ɛ phase mixture as after long-term annealing in the temperature range T eff = 350-589°C. The mass transfer rate driven by high-pressure torsion is 14-18 orders of magnitude higher than the rate of conventional thermal diffusion at the processing temperature T HPT. This phenomenon can be explained by an increased concentration of defects (in particular, vacancies) in the steady state under high-pressure torsion, which is equivalent to an increase in the temperature.

  20. A torsional eye movement calculation algorithm for low contrast images in video-oculography.

    PubMed

    Jansen, S H; Kingma, H; Peeters, R M; Westra, R L

    2010-01-01

    Video-oculography (VOG) is a frequently used clinical technique to detect eye movements. In this research, head mounted small video-cameras and IR-illumination are employed to image the eye. Many algorithms have been developed to extract horizontal and vertical eye movements from the video images. Designing a method to determine torsional eye movements is a more complex task. The use of IR-wavelengths required for illumination in certain clinical tests results in a very low image contrast. In such images, iris textures are almost invisible, making them unsuited for direct application of standard matching algorithms, which are used to calculate torsional eye movements. This research presents the design and implementation of a robust torsional eye movement detection algorithm for VOG. This algorithm uses a new approach to measure the torsional eye movement and is suitable for low contrast videos. The algorithm is implemented in a clinical device and its performance is compared to that of alternative techniques.

  1. Electrically, Chemically, and Photonically Powered Torsional and Tensile Actuation of Hybrid Carbon Nanotube Yarn Muscles

    NASA Astrophysics Data System (ADS)

    Lima, Márcio D.; Li, Na; Jung de Andrade, Mônica; Fang, Shaoli; Oh, Jiyoung; Spinks, Geoffrey M.; Kozlov, Mikhail E.; Haines, Carter S.; Suh, Dongseok; Foroughi, Javad; Kim, Seon Jeong; Chen, Yongsheng; Ware, Taylor; Shin, Min Kyoon; Machado, Leonardo D.; Fonseca, Alexandre F.; Madden, John D. W.; Voit, Walter E.; Galvão, Douglas S.; Baughman, Ray H.

    2012-11-01

    Artificial muscles are of practical interest, but few types have been commercially exploited. Typical problems include slow response, low strain and force generation, short cycle life, use of electrolytes, and low energy efficiency. We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. Electrical, chemical, or photonic excitation of hybrid yarns changes guest dimensions and generates torsional rotation and contraction of the yarn host. Demonstrations include torsional motors, contractile muscles, and sensors that capture the energy of the sensing process to mechanically actuate.

  2. Topological invariants and the dynamics of an axial vector torsion field

    NASA Astrophysics Data System (ADS)

    Drechsler, W.

    1983-08-01

    A generalized theory of gravitation is discussed which is based on a Riemann-Cartan space-time,U 4, with an axial vector torsion field. Besides Einstein's equations determining the metric of theU 4, a system of nonlinear field equations is established coupling an axial vector source current to the axial vector torsion field. The properties of the solutions of these equations are discussed assuming a London-type condition relating the axial current and torsion field. To characterize the solutions use is made of the Euler and Pontrjagin forms and the associated quadratic curvature invariants for theU 4 space-time. It is found that there exists for a Riemann-Cartan space-time a relation between the zeros of the axial vector torsion field and the singularities of the Pontrjagin invariant, which is analogous to the well-known Hopf relation between the zeros of vector fields and the Euler characteristic.

  3. Sudden death in an infant resulting from torsion of the uterine adnexa.

    PubMed

    Havlik, Dean M; Nolte, Kurt B

    2002-09-01

    A 2-month-old infant girl died suddenly as a result of torsion of the uterine adnexa. The infant was found unresponsive in bed and was pronounced dead shortly after her arrival at a hospital. There were no antecedent signs of illness. At autopsy, the right ovary and right fallopian tube were twisted and were dark purple, swollen, and necrotic. The right ovary was enlarged by a follicle cyst 4 cm in diameter, which likely precipitated the torsion. The mechanism of death was unclear but may have resulted from the release of cytokines produced in response to necrotic adnexal tissue. Fatal uterine adnexal torsion has been reported rarely in infants; in all those cases there were antecedent symptoms. Torsion of the uterine adnexa should be included in the differential diagnosis of sudden death in infancy.

  4. Axial Torsion of Gangrenous Meckel's Diverticulum Causing Small Bowel Obstruction

    PubMed Central

    Sasikumar, K.; Noonavath, Ravinder Naik; Sreenath, G. S.; Maroju, Nanda Kishore

    2013-01-01

    Meckel's diverticulum (MD) is a commonly encountered congenital anomaly of the small intestine. We report an extremely unusual case of an axially torted, gangrenous MD presenting as acute intestinal obstruction. A 26-year-old male patient presented to our emergency department with 3 days history of abdominal pain, distention and bilious vomiting. On laparotomy, there was minimal hemorrhagic fluid localized in right iliac fossa and small bowel loops were dilated. A MD was seen attached to the mesentery of nonadjacent small bowel by a peritoneal band. The diverticulum was axially torted and gangrenous. In addition, there was compression of ileum by the peritoneal band resulting in intestinal obstruction, which was relieved on dividing the band. Resection and anastomosis of the small bowel including the MD was performed. We hereby report a rare and unusual complication of a MD. Although treatment outcome is generally good, pre-operative diagnosis is often difficult. PMID:24741431

  5. Anodal transcranial direct current stimulation relieves the unilateral bias of a rat model of Parkinson's disease.

    PubMed

    Li, Yiyan; Tian, Xulong; Qian, Long; Yu, Xuehong; Jiang, Weiwei

    2011-01-01

    The unilaterally lesioned rat model of Parkinson's disease which fails to orient to the food stimuli presented on the contralateral side of its preferential side of body could be induced by the injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle (MFB). We employed transcranial direct current stimulation (tDCS, current intensity: 80 μA, and 40 μA; anodal electrode area: 3.14 mm(2); stimulation time: 30 minutes) over the M1 area to relieve the ipsilateral bias in the rat model. A corridor test was set to count the ipsilateral bias of the rats. In this experiment, 30 Sprague-Dawley rats (80 μA: n = 8, 40 μA: n = 8, sham: n = 7, healthy control: n = 7) were chosen for the corridor test and the tDCS session. The lesioned rats exhibited increased ipsilateral bias 4 weeks after the lesion surgery (P < 0.01), and the anodal tDCS with the active electrode on the lesioned side relieved the ipsilateral bias significantly (P < 0.01) immediately after the surgery and the improvement lasted for nearly 1 day. The rats in the group of 80 μA exhibited more significant changes than the 40 μA group after one day. After all the experiments, the histological process showed no neurotrauma led by the tDCS. In conclusion, the modulatory function of the cortical excitability of the tDCS may awaken the compensatory mechanisms and the response mechanisms which modulate the loss of the brain function. Further studies should be done to provide more evidence about the assumption.

  6. Does cigarette smoking relieve stress? Evidence from the event-related potential (ERP).

    PubMed

    Choi, Damee; Ota, Shotaro; Watanuki, Shigeki

    2015-12-01

    Previous studies have reported a paradox that cigarette smoking reduces stress psychologically; however, it increases the arousal level physiologically. To examine this issue, our study aimed to investigate whether cigarette smoking relieves stress by measuring the late positive potential (LPP), a component of the event-related potential (ERP). In Experiment 1, participants first watched emotionally neutral images; second, they received a break; and finally, they watched emotionally neutral images again. In the break, they smoked a cigarette (smoking condition) or simply rested without smoking (non-smoking condition). The procedure of Experiment 2 was the same as that of Experiment 1, except that the participants watched unpleasant images as stress stimuli before the break. In Experiment 1, the LPP decreased from before to after the break in the smoking condition, but not in the non-smoking condition, suggesting that smoking cigarettes in the neutral state reduces the arousal level. In Experiment 2, the LPP for 400-600 ms decreased from before to after the break, both in the smoking and non-smoking conditions; however, the LPP for 200-400 ms decreased from before to after the break only in the smoking condition. This suggests the possibility that cigarette smoking in the unpleasant state may facilitate a decrease in the arousal level faster than with non-smoking. In both Experiments 1 and 2, the subjective rating results also suggested that cigarette smoking decreased anxiety. Taken together, both the physiological (LPP) and the psychological responses from our study suggest that cigarette smoking perhaps relieves stress.

  7. Counterintuitive DNA Sequence Dependence in Supercoiling-Induced DNA Melting

    PubMed Central

    Vlijm, Rifka; v.d. Torre, Jaco; Dekker, Cees

    2015-01-01

    The metabolism of DNA in cells relies on the balance between hybridized double-stranded DNA (dsDNA) and local de-hybridized regions of ssDNA that provide access to binding proteins. Traditional melting experiments, in which short pieces of dsDNA are heated up until the point of melting into ssDNA, have determined that AT-rich sequences have a lower binding energy than GC-rich sequences. In cells, however, the double-stranded backbone of DNA is destabilized by negative supercoiling, and not by temperature. To investigate what the effect of GC content is on DNA melting induced by negative supercoiling, we studied DNA molecules with a GC content ranging from 38% to 77%, using single-molecule magnetic tweezer measurements in which the length of a single DNA molecule is measured as a function of applied stretching force and supercoiling density. At low force (<0.5pN), supercoiling results into twisting of the dsDNA backbone and loop formation (plectonemes), without inducing any DNA melting. This process was not influenced by the DNA sequence. When negative supercoiling is introduced at increasing force, local melting of DNA is introduced. We measured for the different DNA molecules a characteristic force Fchar, at which negative supercoiling induces local melting of the dsDNA. Surprisingly, GC-rich sequences melt at lower forces than AT-rich sequences: Fchar = 0.56pN for 77% GC but 0.73pN for 38% GC. An explanation for this counterintuitive effect is provided by the realization that supercoiling densities of a few percent only induce melting of a few percent of the base pairs. As a consequence, denaturation bubbles occur in local AT-rich regions and the sequence-dependent effect arises from an increased DNA bending/torsional energy associated with the plectonemes. This new insight indicates that an increased GC-content adjacent to AT-rich DNA regions will enhance local opening of the double-stranded DNA helix. PMID:26513573

  8. Analysis of the Rotation-Torsion Spectrum of CH_2DOH Within the e_0, e_1, and o_1 Torsional Levels

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.; Pearson, John C.; Yu, Shanshan; Margules, L.; Motiyenko, R. A.; Klee, S.

    2013-06-01

    Since the first assignments of Quade and coworkers, a more satisfactory understanding of the spectrum of CH_2DOH has now been achieved. Thanks to a multidimensional potential energy surface and to a new theoretical approach accounting for the internal rotation of a partially deuterated methyl group, 76 torsional subbands could be identified in the microwave and FIR domains. 8356 rotation and rotation-torsion transitions were also assigned for the three lowest lying torsional levels, e_0, e_1, and o_1, in the microwave and terahertz domains and were analyzed with empirical models. In this paper, a new approach aimed at accounting for the rotation-torsion energy levels of CH_2DOH will be presented. It is based on the exact expression of the generalized 4× 4 inertia tensor of the molecule and accounts for the C_s symmetry of the partially deuterated methyl group, for the dependence of the rotational constants on the angle of internal rotation, and for the rotation-torsion Coriolis coupling. This approach will be used to analyze high-resolution data involving the three lowest lying torsional levels, up to k=11. In addition to the microwave data reported recently,^d new transitions recorded in the terahertz domain at JPL will be analyzed. The results of the analysis will be presented in the paper and the parameters determined in the analysis will be discussed. Quade and Suenram, J. Chem. Phys. {73} (1980) 1127; and Su and Quade, J. Mol. Spec. {134} (1989) 290. Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spec. {256} (2009) 204. El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. {135} (2011) 194309. Pearson, Yu, and Drouin, J. Mol. Spec. {280} (2012) 119. Quade and Lin, J. Chem. Phys. {38} (1963) 540.

  9. Communication: Accurate determination of side-chain torsion angle χ1 in proteins: Phenylalanine residues

    NASA Astrophysics Data System (ADS)

    Suardíaz, R.; Crespo-Otero, R.; Pérez, C.; Fabián, J. San; de la Vega, J. M. García

    2011-02-01

    Quantitative side-chain torsion angle χ1 determinations of phenylalanine residues in Desulfovibrio vulgaris flavodoxin are carried out using exclusively the correlation between the experimental vicinal coupling constants and theoretically determined Karplus equations. Karplus coefficients for nine vicinal coupling related with the torsion angle χ1 were calculated using the B3LYP functional and basis sets of different size. Optimized χ1 angles are in outstanding agreement with those previously reported by employing x ray and NMR measurements.

  10. Detection of the torsionally excited state of methanol in Orion A

    NASA Technical Reports Server (NTRS)

    Lovas, F. J.; Suenram, R. D.; Snyder, L. E.; Hollis, J. M.; Lees, R. M.

    1982-01-01

    Torsionally excited methanol has been detected in Orion A, where three emission lines observed in the region of 93-100 GHz coincide with laboratory measurements of three methanol transitions. Torsionally excited methanol may therefore be used as a novel temperature probe, since this state lies near 200 per cm above the ground state, or about 290 K. No emission was detected from the transition arising from levels near 300 per cm, or approximately 430 K above the ground state.

  11. Persistent Down-Beating Torsional Positional Nystagmus: Posterior Semicircular Canal Light Cupula?

    PubMed Central

    Otsuka, Koji

    2016-01-01

    A 16-year-old boy with rotatory positional vertigo and nausea, particularly when lying down, visited our clinic. Initially, we observed vertical/torsional (downward/leftward) nystagmus in the supine position, and it did not diminish. In the sitting position, nystagmus was not provoked. Neurological examinations were normal. We speculated that persistent torsional down-beating nystagmus was caused by the light cupula of the posterior semicircular canal. This case provides novel insights into the light cupula pathophysiology. PMID:27668113

  12. Comparison of 45-degree Kelman and 45-degree balanced phaco tip designs in torsional microcoaxial phacoemulsification

    PubMed Central

    Demircan, Süleyman; Ataş, Mustafa; Göktaş, Emre; Başkan, Burhan

    2015-01-01

    AIM To compare the intraoperative performance and postoperative outcome after microcoaxial torsional phacoemulsification using either a Kelman or balanced phaco tip. METHODS Cataracts were treated using 2.2 mm microcoaxial torsional phacoemulsification using either a 45-degree mini-flared Kelman® or a 45-degree Intrepid® Balanced phaco tip. Intraoperative measurements included total ultrasound (US) time, cumulative dissipated energy (CDE), torsional US time, and balanced salt solution (BSS) use. The central endothelial cell density (ECD) and central corneal thickness (CCT) were evaluated preoperatively and postoperatively 1, 7, and 30d after surgery using noncontact specular microscopy. RESULTS The 116 enrolled eyes (116 patients) were divided equally between the Kelman and balanced tip groups. Intraoperative measurements showed significantly less total US time, torsional US time, CDE, and BSS use in the balanced group than in Kelman group (P<0.05). The total US time, torsional US time, CDE, and BSS use were 17.45±14.53s, 16.63±13.97s, 6.38±5.26, and 48.21±17.21 mL in the Kelman group and 11.39 ± 9.60s, 10.90 ± 9.25s, 4.04 ± 3.42, and 41.36 ± 12.70 mL in the balanced group, respectively. CONCLUSION Torsional phacoemulsification performed with a balanced tip provided more effective lens removal with less total US time, torsional time, CDE, and BSS use, as well as similar changes in ECD with a Kelman tip in all cataract grades. This special designed phaco tip for torsional phacoemulsification provides an alternative phaco tip for many surgeons' preference with straight phaco tip. PMID:26682167

  13. Application of Maximum Entropy principle to modeling torsion angle probability distribution in proteins

    NASA Astrophysics Data System (ADS)

    Rowicka, Małgorzata; Otwinowski, Zbyszek

    2004-04-01

    Using the Maximum Entropy principle, we find probability distribution of torsion angles in proteins. We estimate parameters of this distribution numerically, by implementing the conjugate gradient method in Polak-Ribiere variant. We investigate practical approximations of the theoretical distribution. We discuss the information content of these approximations and compare them with standard histogram method. Our data are pairs of main chain torsion angles for a selected subset of high resolution non-homologous protein structures from Protein Data Bank.

  14. Ruptured Ectopic Pregnancy with Contralateral Ovarian Serous Cyst Adenoma Torsion: Laparoscopic Management of Double Trouble

    PubMed Central

    Rajkumar, Anirudh; Rajkumar, J. S.; Guru, Venkatesan

    2016-01-01

    Adnexal torsion is responsible for 2.7% of all gynecological emergencies. Ectopic pregnancy is relatively common, occurring in 2% of all pregnancies. We report the second case of ruptured right tubal ectopic gestation with torsion of serous cystadenoma of left ovary. This was diagnosed after emergency laparoscopy done for acute abdomen. Right salpingectomy and left ovarian detorsion followed by cystectomy were done laparoscopically. PMID:27840755

  15. Ocular torsion measured by TV- and scanning laser ophthalmoscopy during horizontal pursuit in humans and monkeys.

    PubMed

    Ott, D; Eckmiller, R

    1989-12-01

    Ocular torsion during horizontal foveal pursuit and fixation was measured in five human subjects and two trained monkeys (Macaca fascicularis) by direct analysis of the ocular fundus rotation. In the monkeys the fundus images of either eye were generated with a TV-ophthalmoscope while the contralateral eye pursued an 8' visual target moving sinusoidally (0.3-0.9 Hz, +/- 5 degrees) in the horizontal plane. In the humans a scanning laser ophthalmoscope (SLO) generated the fundus image of the ipsilateral eye, which pursued the visual target (same parameters as in the monkeys) mixed electronically into the laser scan raster. The image sequences were stored on videotape and subjected to a frame-by-frame rotation analysis. In both the humans and the monkeys, torsion (fundus rotation about the visual axis) sinusoidally modulated (up to 8 degrees peak-to-peak) during foveal pursuit, approximately in phase with horizontal eye position. Intorsion (nasal movement of the upper eye pole) or extorsion was found during pursuit in the temporal or nasal direction. Torsion showed considerable intra-individual fluctuation and interindividual variability with regard to phase and modulation depth relative to the pursuit movements, and was interspersed with irregularly occurring rapid deflections. Torsion of the conjugate, nonpursing eye was similar to torsion of the pursuing eye. In contrast, torsion during fixation was only loosely correlated with horizontal eye position. Slow torsional drifts and large, rapid deflections (up to 6 degrees) occurred in either direction at a given fixation point in the horizontal plane. We conclude that ocular torsion during horizontal pursuit in primates is actively generated by a separate, neural oculomotor subsystem.(ABSTRACT TRUNCATED AT 250 WORDS)

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

    DTIC Science & Technology

    1987-01-01

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

  17. Torsion of wandering spleen as a rare reason for acute abdomen: A presentation of two cases.

    PubMed

    Yılmaz, Özkan; Bayrak, Vedat; Daştan, Ertuğrul; Kotan, Çetin

    2013-01-01

    Wandering spleen is a rare disease that is clinically characterized by torsion of the pedicle. The congenital absence of ligaments anchoring the spleen to the left sub-phrenic area or an acquired looseness is the major reason behind its mobilization. Unless splenic torsion occurs and acute abdominal clinical symptomatology develops, clinical diagnosis is highly challenging due to lack of symptoms. This study aims to share the information acquired from two encountered cases accompanied by the relevant literature.

  18. Acute torsion of wandering spleen in a 17-year-old girl.

    PubMed

    Jiang, Maoqing; Chen, Ping; Ruan, Xinzhong; Ye, Xianwang; Huang, Qiuli

    2015-01-01

    The acute torsion of wandering spleen is a very rare disease characterized by acute abdominal pain. Without early surgical intervention, wandering spleen can lead to splenic infarction or rupture. However, early clinical diagnosis is very difficult, so imaging modalities play an important role. We present a case of acute abdominal pain due to torsion of the wandering spleen in a 17-year-old girl, diagnosed by computed tomography and effectively managed by splenectomy for splenic infarction.

  19. Acute torsion of wandering spleen in a 17-year-old girl

    PubMed Central

    Jiang, Maoqing; Chen, Ping; Ruan, Xinzhong; Ye, Xianwang; Huang, Qiuli

    2015-01-01

    The acute torsion of wandering spleen is a very rare disease characterized by acute abdominal pain. Without early surgical intervention, wandering spleen can lead to splenic infarction or rupture. However, early clinical diagnosis is very difficult, so imaging modalities play an important role. We present a case of acute abdominal pain due to torsion of the wandering spleen in a 17-year-old girl, diagnosed by computed tomography and effectively managed by splenectomy for splenic infarction. PMID:26379994

  20. Investigation of Torsional Strength of the VT6 Weld Joint Produced by Linear Friction Welding

    NASA Astrophysics Data System (ADS)

    Suleimanova, G. R.; Kabirov, R. R.; Karavaeva, M. V.; Ershova, Yu. A.; Zhilyaev, A. P.

    2015-10-01

    Results of measurement of torsional strength of the weld joint of the VT6 titanium alloy produced by linear friction welding are presented. For a comparison, the same method was used to test monolithic specimens of the VT6 alloy. Torsional strength values of the weld joint (τUS = 861 MPa and φ = 110°) correspond to the strength of the monolithic material. In this case, the specimens fail along the base metal.

  1. New improved massive gravity and three-dimensional spacetimes of constant curvature and constant torsion

    NASA Astrophysics Data System (ADS)

    Dereli, Tekin; Yetişmişoǧlu, Cem

    2016-09-01

    We derive the field equations for topologically massive gravity coupled with the most general quadratic curvature terms using the language of exterior differential forms and a first order constrained variational principle. We find variational field equations both in the presence and absence of torsion. We then show that spaces of constant negative curvature (i.e. the anti-de Sitter space AdS3) and constant torsion provide exact solutions.

  2. Transabdominal color doppler ultrasonography: A relevant approach for assessment of effects of uterine torsion in buffaloes

    PubMed Central

    Devender; Chandolia, Ramesh Kumar; Pandey, Anand Kumar; Yadav, Vishal; Kumar, Parveen; Dalal, Jasmer

    2016-01-01

    Aim: The present study was conducted on advanced pregnant buffaloes suffering from uterine torsion to assess the status of fetus and uterus by transabdominal ultrasonography, and the findings were compared with normal advanced pregnant buffaloes. Materials and Methods: The study was conducted on 20 clinical cases of uterine torsion and 20 normal advanced pregnant buffaloes (control group). The lower ventral area just lateral to linea alba (on both sides of the udder) in standing animals was scanned transabdominally by the two-dimensional convex transducer for various ultrasonographic findings. The data collected were statistically analyzed by “one-way ANOVA” and “independent sample t-test” using computerized SPSS 16.0 software program. Results: Transabdominal ultrasonography revealed dead fetus in 95% uterine torsion cases and proved useful in imaging internal structures of fetuses while no dead fetus was reported in the control group. Size of umbilicus was found significantly decreased (p<0.05) in uterine torsion group in comparison to control animals, but the decrease in placentomal area was marginal (p>0.05) in uterine torsion group. Average thickness of the uterine wall and mean pixel values of fetal fluids (echogenicity) were found significantly increased (p<0.05) in uterine torsion affected buffaloes in comparison to control group. Conclusion: Status of fetus (whether live or dead), internal status of uterus, and its contents could be determined by transabdominal ultrasonography in uterine torsion cases and thus determining the prognosis of the uterine torsion cases before going for further manipulations. This will also help in taking all the precautions to avoid death of the fetus. PMID:27651672

  3. Torsion - Vibration Couplings in the CH{_3}OO{\\cdot} Radical

    NASA Astrophysics Data System (ADS)

    Huang, Meng; Miller, Terry A.; McCoy, Anne B.; Hsu, Kuo-Hsiang; Huang, Yu-Hsuan; Lee, Yuan-Pern

    2016-06-01

    A partially rotationally resolved infrared spectrum of CH{_3}OO{\\cdot} in the CH stretch region has been reported. The rotational contour of the {ν_2} CH stretch band in the experimental spectrum can be simulated with an asymmetric rotor model. The simulation shows good agreement with the experimental spectrum except that the broadening of the Q-branch in the experimental spectrum remains unexplained. This broadening is likely due to the sequence band transitions from the torsionally excited levels populated at room temperature to combination levels involving the CH stretch and the same number of torsional quanta. A four dimension model involving three CH stretches and the CH{_3} torsion is applied to the CH{_3}OO{\\cdot} radical to obtain the frequencies and intensities of the vibrational transitions in the CH stretch region. Based on these calculations, the torsional sequence bands are calculated to be slightly shifted from the origin band, because of the couplings between the CH stretches and CH{_3} torsion, thereby causing the apparent broadening observed for the {ν_2} fundamental. Due to the accidental degeneracy of two different CH stretch and CH{_3} torsion combination levels which differ by one quantum in the torsional excitation, the frequencies of the torsional sequence bands will be very sensitive to details of the potential, which makes the shifts difficult to precisely predict with electronic structure calculations. Complementary analyses are now underway for the other two CH stretch vibrational bands, {ν_1} and {ν_9}. K.-H. Hsu, Y.-H. Huang, Y.-P. Lee, M. Huang, T. A. Miller and A. B. McCoy J. Phys. Chem. A, in press, DOI: 10.1021/acs.jpca.5b12334

  4. Third place winner. Three-year-old female with intermittent ovarian torsion.

    PubMed

    Kienstra, Andrew J; Ward, Mark A

    2002-11-01

    We report an atypical case of ovarian torsion, an uncommon cause of abdominal pain in a very young girl. She presented with intermittent episodes of groin and thigh pain over a 10-week period. The child had minimal objective findings at the time of each evaluation. Despite the delay in diagnosis, the ovary was preserved. Despite its rarity, ovarian torsion must be considered in the differential diagnosis of abdominal pain in young girls.

  5. Blood perfusion of the contralateral testis evaluated with contrast-enhanced ultrasound in rabbits with unilateral testicular torsion.

    PubMed

    Chen, Lin; Zhan, Wei-Wei; Shen, Zhou-Jun; Rui, Wen-Bin; Lv, Chen; Chen, Man; Zhou, Jian-Qiao; Zhou, Ping; Zhou, Mi; Zhu, Ying

    2009-03-01

    The changes of blood perfusion of contralateral testis after unilateral testicular torsion remain controversial. In this study, 28 New Zealand white male rabbits were randomly divided into five groups. Group A (n = 8), the control group, underwent a sham operation on the unilateral testis without inducing testicular torsion. In groups B, C, and D (n = 5 each), unilateral testicular torsion was induced, and, after 3, 6 or 24 h, respectively, detorsion was performed. In group E (n = 5), permanent unilateral testicular torsion was applied. Contrast-enhanced ultrasound was used to observe the blood perfusion of the contralateral testis at the following stages: pre-torsion (preopration), immediately post-torsion (postopration), pre-detorsion, immediately post-detorsion, and late-stage post-detorsion (6-12 h post-detorsion in groups B-D) or at a similar time point (15-21 h post-torsion in group E). Time-intensity curves were generated, and the following parameters were derived and analyzed: arrival time, time to peak intensity, peak intensity, and half-time of the descending peak intensity. The analysis revealed that blood perfusion of the contralateral testis increased immediately after testicular torsion on the opposite side (P < 0.05), which increased with prolonged testicular torsion of the other testis. This research demonstrated that contrast-enhanced ultrasound was valuable in evaluating blood perfusion of the contralateral testis after unilateral testicular torsion.

  6. Diabatic Versus Adiabatic Calculation of Torsion-Vibration Interactions

    NASA Astrophysics Data System (ADS)

    Hougen, Jon T.

    2013-06-01

    The introductory part of this talk will deal briefly with two historical topics: (i) use of the words adiabatic, nonadiabatic, and diabatic in thermodynamics and quantum mechanics, and (ii) application of diabatic and adiabatic ideas to vibrational energy level calculations for a pair of diatomic-molecule potential energy curves exhibiting an avoided crossing. The main part of the talk will be devoted to recent work with Li-Hong Xu and Ron Lees on how ab initio projected frequency calculations for small-amplitude vibrations along the large-amplitude internal rotation path in methanol can best be used to help guide experimental assignments and fits in the IR vibrational spectrum. The three CH stretching vibrations for CH_{3}OH can conveniently be represented as coefficients multiplying three different types of basis vibrations, i.e., as coefficients of: (i) the local mode C-H_i bond displacements δr_{i} for hydrogens H_{1}, H_{2} and H_{3} of the methyl top, (ii) symmetrized linear combinations of the three δr_{i} of species A_{1} oplus E in the permutation-inversion group G_{6} = C_{3v} appropriate for methanol, or (iii) symmetrized linear combinations of the three δr_{i} of species 2A_{1} oplus A_{2} in the permutation-inversion group G_{6}. In this talk, we will focus on diabatic and adiabatic computations for the A_{1} oplus E basis vibrations of case (ii) above. We will briefly explain how Jahn-Teller-like and Renner-Teller-like torsion-vibration interaction terms occurring in the potential energy expression in the diabatic calculation become torsion-vibration Coriolis interaction terms occurring in the kinetic energy expression of the adiabatic calculations, and also show how, for algebraically solvable parameter choices, the same energy levels are obtained from either calculation. A final conclusion as to which approach is computationally superior for the numerical data given in a quantum chemistry output file has not yet been arrived at.

  7. Division of the genitofemoral nerve and late orchiectomy: effects on the contralateral testis in ipsilateral testicular torsion.

    PubMed

    Tander, B; Sarica, K; Baskin, D; Abbasoğlu, L; Sakiz, D; Bulut, M

    1998-11-01

    Unilateral torsion of the spermatic cord has been demonstrated to damage the contralateral testis; however, the pathogenesis has not yet been examined in detail. The purpose of this study was to evaluate the influence of unilateral torsion on the contralateral testis in rats by performing ipsilateral division of the genitofemoral nerve (GFN) and/or late orchiectomy. Male 25-day-old, prepubertal Wistar albino rats were divided into five groups: (1) sham operation; (2) unilateral testicular torsion; (3) simultaneous unilateral testicular torsion and ipsilateral GFN division; (4) unilateral testicular torsion and orchiectomy on the 4th day after torsion; and (5) simultaneous unilateral testicular torsion and GFN ipsilateral division, and orchiectomy on the 4th day after torsion. Torsions performed were 720 degrees, all on the right testes. On day 55 after torsion, which represents the early postpubertal period of the rat, the contralateral testes were removed. Tubular biopsy score (TBS) was calculated, and seminiferous tubular diameters (STD) were measured. Student's t-test was used for statistical analysis. There was no contralateral testicular damage in the control group, but in all of the study groups destructive changes were found in the left gonad after torsion of the right testicle. The mean TBS of the study groups was higher than that of the control group. STD values were lower in the study groups, but the differences were not statistically significant between groups. In prepubertal rats, unilateral torsion causes histologically measurable changes in the contralateral testis. Ipsilateral division of the GFN and late orchiectomy did not cause any significant alterations in terms of contralateral damage. Further investigations are needed to determine the role of the GFN in testicular torsion.

  8. Non-minimal coupling of torsion-matter satisfying null energy condition for wormhole solutions

    NASA Astrophysics Data System (ADS)

    Jawad, Abdul; Rani, Shamaila

    2016-12-01

    We explore wormhole solutions in a non-minimal torsion-matter coupled gravity by taking an explicit non-minimal coupling between the matter Lagrangian density and an arbitrary function of the torsion scalar. This coupling describes the transfer of energy and momentum between matter and torsion scalar terms. The violation of the null energy condition occurred through an effective energy-momentum tensor incorporating the torsion-matter non-minimal coupling, while normal matter is responsible for supporting the respective wormhole geometries. We consider the energy density in the form of non-monotonically decreasing function along with two types of models. The first model is analogous to the curvature-matter coupling scenario, that is, the torsion scalar with T-matter coupling, while the second one involves a quadratic torsion term. In both cases, we obtain wormhole solutions satisfying the null energy condition. Also, we find that the increasing value of the coupling constant minimizes or vanishes on the violation of the null energy condition through matter.

  9. Torsional Vibration in the National Wind Technology Center’s 2.5-Megawatt Dynamometer

    SciTech Connect

    Sethuraman, Latha; Keller, Jonathan; Wallen, Robb

    2016-08-31

    This report documents the torsional drivetrain dynamics of the NWTC's 2.5-megawatt dynamometer as identified experimentally and as calculated using lumped parameter models using known inertia and stiffness parameters. The report is presented in two parts beginning with the identification of the primary torsional modes followed by the investigation of approaches to damp the torsional vibrations. The key mechanical parameters for the lumped parameter models and justification for the element grouping used in the derivation of the torsional modes are presented. The sensitivities of the torsional modes to different test article properties are discussed. The oscillations observed from the low-speed and generator torque measurements were used to identify the extent of damping inherently achieved through active and passive compensation techniques. A simplified Simulink model of the dynamometer test article integrating the electro-mechanical power conversion and control features was established to emulate the torque behavior that was observed during testing. The torque response in the high-speed, low-speed, and generator shafts were tested and validated against experimental measurements involving step changes in load with the dynamometer operating under speed-regulation mode. The Simulink model serves as a ready reference to identify the torque sensitivities to various system parameters and to explore opportunities to improve torsional damping under different conditions.

  10. Modeling and testing miniature torsion specimens for SiC joining development studies for fusion

    DOE PAGES

    Henager, Jr., C. H.; Nguyen, Ba N.; Kurtz, Richard J.; ...

    2015-08-05

    The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. For this research, miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti3SiC2 + SiC joints with SiC and tested in torsion-shear prior to and after neutron irradiation. However, many miniature torsion specimens fail out-of-plane within the SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated strengths to determine irradiation effects. Finite elementmore » elastic damage and elastic–plastic damage models of miniature torsion joints are developed that indicate shear fracture is more likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated test data for a variety of joint materials. The unirradiated data includes Ti3SiC2 + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. Finally, the implications for joint data based on this sample design are discussed.« less

  11. A Theoretical Study of the Methyl and Aldehyde Torsion FIR Spectra in Symmetric Propanal Isotopomers

    NASA Astrophysics Data System (ADS)

    Smeyers, Y. G.; Villa, M.; Uc, V. H.; Vivier-Bunge, A.

    2000-05-01

    This paper is an extension of the techniques developed by us [A. Vivier-Bunge, V. H. Uc, and Y. G. Smeyers, J. Chem. Phys. 109, 2279 (1998)] for standard propanal. In that paper the potential energy surface for the simultaneous methyl and asymmetric aldehydic torsions was calculated at RHF/MP2 level using the 6-311(3df,p) basis set for propanal. The fit of the energy values to symmetry-adapted functional forms was carried out by using the 28 energy values which retain the C3 dynamical symmetry of the methyl group in the optimization procedure. With this potential, as well as with the kinetic parameters and the electric dipole moment variations, the FIR frequencies and intensities for the methyl and aldehyde torsions of seven symmetric isotopomers of propanal were determined theoretically using two-dimensional calculations. The calculated spectra of propanal and three of its isotopomers were compared with the available experimental data. It is found that the calculations for the cis conformer satisfactorily reproduce the aldehyde and methyl torsion spectra and furnish also methyl torsionally excited progressions for the aldehyde torsion modes. The methyl torsion frequencies agree especially well whenever the methyl group is nondeuterated. The small deviations encountered for the deuterated compound are probably due to some mass effect, such as the zero-point vibrational energy correction, which is not taken into account in the present calculations. Finally, the influence of the deuteration on the intensities is discussed.

  12. Modeling and Testing Miniature Torsion Specimens for SiC Joining Development Studies for Fusion

    SciTech Connect

    Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.; Roosendaal, Timothy J.; Borlaug, Brennan A.; Ferraris, Monica; Ventrella, Andrea; Katoh, Yutai

    2015-08-19

    The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. Miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti3SiC2 + SiC joints with CVD-SiC and tested in torsion-shear prior to and after neutron irradiation. However, many of these miniature torsion specimens fail out-of-plane within the CVD-SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated joint strengths to determine the effects of the irradiation. Finite element elastic damage and elastic-plastic damage models of miniature torsion joints are developed that indicate shear fracture is likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated joint test data for a variety of joint materials. The unirradiated data includes Ti3SiC2 + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. The implications for joint data based on this sample design are discussed.

  13. Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis

    NASA Astrophysics Data System (ADS)

    Feng, S. D.; Jiao, W.; Jing, Q.; Qi, L.; Pan, S. P.; Li, G.; Ma, M. Z.; Wang, W. H.; Liu, R. P.

    2016-11-01

    Structural evolution in nanoscale Cu50Zr50 metallic glasses during high-pressure torsion is investigated using molecular dynamics simulations. Results show that the strong cooperation of shear transformations can be realized by high-pressure torsion in nanoscale Cu50Zr50 metallic glasses at room temperature. It is further shown that high-pressure torsion could prompt atoms to possess lower five-fold symmetries and higher potential energies, making them more likely to participate in shear transformations. Meanwhile, a higher torsion period leads to a greater degree of forced cooperative flow. And the pronounced forced cooperative flow at room temperature under high-pressure torsion permits the study of the shear transformation, its activation and characteristics, and its relationship to the deformations behaviors. This research not only provides an important platform for probing the atomic-level understanding of the fundamental mechanisms of high-pressure torsion in metallic glasses, but also leads to higher stresses and homogeneous flow near lower temperatures which is impossible previously.

  14. The effect of space missions on gravity-responsive torsional eye movements

    NASA Technical Reports Server (NTRS)

    Diamond, S. G.; Markham, C. H.

    1998-01-01

    Three astronauts underwent preflight, inflight, and postflight testing of spontaneous ocular torsion and of ocular counterrolling (OCR), reflexes governed by the gravity-responsive otolith organs in the inner ear. One astronaut, A, had a 30-day space mission on Euromir '94 and was examined monocularly with SensoMotoric Instruments video-oculography (VOG). The other two astronauts, B and C, were studied with a binocular VOG and flew an 180-day mission on Euromir '95. In space, spontaneous eye torsion in the upright position was found to be substantially offset from baseline Earth-based recordings in all three subjects for the duration of the flights. In addition, the binocular studies showed a marked torsional disconjugacy. On return to Earth, offset and torsional disconjugacy persisted for many days. OCR in response to 30 degrees right and left tilt was examined preflight and postflight. Compared to preflight, Astronaut A showed reduced OCR immediately postflight, which increased over the next few days. Both Astronauts B and C had increased OCR postflight, which gradually approached but did not achieve the preflight values over 13 days postflight. The adaptation of ocular torsion in space in one astronaut and not in the other two, and slow adaptation postflight, may reflect the lack of visual feed-back and the open loop nature of the otolith-ocular torsion reflex.

  15. Torsion of the central pair microtubules in eukaryotic flagella due to bending-driven lateral buckling

    SciTech Connect

    Li, C.; Ru, C.Q. . E-mail: c.ru@ualberta.ca; Mioduchowski, A.

    2006-12-08

    Inspired by recent interest in torsion of the central pair microtubules in eukaryotic flagella, a novel thin-walled elastic beam model is suggested to study critical condition under which uniform bending of a flagellum will cause lateral/torsional buckling of the central pair. The model is directed to the central pair itself and the role of all surrounding cross-linkings inside the flagellum is modeled as an equivalent surrounding elastic medium. The model predicts that bending-driven torsion of the central pair does occur when the radius of curvature of the bent flagellum reduces to a moderate critical value typically of tens of microns. In particular, this critical value is almost independent of the flagellum length, and more sensitive to the parameters defining the surrounding elastic medium than the shear modulus of microtubules. The predicted wavelengths of the torsional buckling mode are insensitive to the flagellum length and comparable to some known related experimental data. These results indicate that torsion of the central pair microtubules in flagella is inevitable as a result of bending-driven lateral buckling. This offers an entirely new insight into the ongoing research on the mechanism of the central pair torsion.

  16. Modeling and testing miniature torsion specimens for SiC joining development studies for fusion

    NASA Astrophysics Data System (ADS)

    Henager, C. H.; Nguyen, B. N.; Kurtz, R. J.; Roosendaal, T. J.; Borlaug, B. A.; Ferraris, M.; Ventrella, A.; Katoh, Y.

    2015-11-01

    The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. Miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti3SiC2 + SiC joints with SiC and tested in torsion-shear prior to and after neutron irradiation. However, many miniature torsion specimens fail out-of-plane within the SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated strengths to determine irradiation effects. Finite element elastic damage and elastic-plastic damage models of miniature torsion joints are developed that indicate shear fracture is more likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated test data for a variety of joint materials. The unirradiated data includes Ti3SiC2 + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. The implications for joint data based on this sample design are discussed.

  17. Prevalence of abnormal CT findings in patients with proven ovarian torsion and a proposed triage schema.

    PubMed

    Moore, Christopher; Meyers, Arthur B; Capotasto, Juliana; Bokhari, Jamal

    2009-03-01

    Many women with ovarian torsion present with nonspecific abdominal/pelvic pain and initially receive computed tomography (CT). We hypothesize that the CT scans preformed on these women will all show abnormalities of the involved ovary. Our purpose is to review cases of surgically proven ovarian torsion at our institution over the last 20 years, assessing CT findings in women with ovarian torsion. A retrospective review of all patients at our institution with surgically proven ovarian torsion from 1985-2005 was conducted. Two physicians reviewed available CT reports, and a radiologist reviewed all available images. CT was obtained in 33% of the 167 patients. Dictated reports were available for 28 studies; all described an enlarged ovary, ovarian cyst, or adnexal mass of the involved ovary. Radiologist review of the available CT images confirmed these findings. This series supports the claim that a CT scan with well-visualized normal appearing ovaries rules out ovarian torsion, while abnormal pelvic findings or failure to visualize the ovaries in women with pelvic pain necessitates further evaluation of torsion.

  18. Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis

    PubMed Central

    Feng, S. D.; Jiao, W.; Jing, Q.; Qi, L.; Pan, S. P.; Li, G.; Ma, M. Z.; Wang, W. H.; Liu, R. P.

    2016-01-01

    Structural evolution in nanoscale Cu50Zr50 metallic glasses during high-pressure torsion is investigated using molecular dynamics simulations. Results show that the strong cooperation of shear transformations can be realized by high-pressure torsion in nanoscale Cu50Zr50 metallic glasses at room temperature. It is further shown that high-pressure torsion could prompt atoms to possess lower five-fold symmetries and higher potential energies, making them more likely to participate in shear transformations. Meanwhile, a higher torsion period leads to a greater degree of forced cooperative flow. And the pronounced forced cooperative flow at room temperature under high-pressure torsion permits the study of the shear transformation, its activation and characteristics, and its relationship to the deformations behaviors. This research not only provides an important platform for probing the atomic-level understanding of the fundamental mechanisms of high-pressure torsion in metallic glasses, but also leads to higher stresses and homogeneous flow near lower temperatures which is impossible previously. PMID:27819352

  19. Testicular torsion and its effects on the spermatogenic cycle in the contralateral testis of the rat.

    PubMed

    Vigueras, R M; Reyes, G; Rojas-Castañeda, J; Rojas, P; Hernández, R

    2004-07-01

    The aim of the present study was to evaluate the effects of unilateral testicular torsion on the contralateral testis with respect to the stages of the cycle of the seminiferous epithelium (CSE). Fifty-five male Wistar rats, 60 days old, were used. The animals were divided into 11 groups. Groups 1-5 were subjected to unilateral testicular torsion from 3 to 48 h, followed by detorsion. Groups 6-10 had unilateral orchiectomies after unilateral testicular torsion for 3 to 48 h. Animals constituting group 11 served as the control sham-operated group. All animals were killed after 2 months. The percentage of affected tubules (tubules showing pathological changes) in the contralateral testis was estimated based on the CSE stages. In the torsion/detorsion group, the percentage of affected tubules was significantly greater (58.6%) than in torsion/orchiectomy group (48.0%). Stages VI-XI of the spermatogenic cycle were the most affected when compared with the rest of the stages in each experimental group (P <0.05). These results show that stages VI-XI of the spermatogenic cycle, the stages associated with low antioxidant capacities, are the most sensitive to the effects of testicular torsion on the contralateral testis.

  20. Analyzing head roll and eye torsion by means of offline image processing.

    PubMed

    Sarès, Frédéric; Granjon, Lionel; Benraiss, Abdelrhani; Boulinguez, Philippe

    2007-08-01

    Ocular torsion is a key problem in the understanding of many visual perceptual effects. However, since it is difficult to record, its integration with other sensorimotor signals is still poorly understood. Unfortunately, eyetracker systems are generally not dedicated to the monitoring of eye torsion. In addition, the classical methods used with video-based systems present some limits in the accuracy of torsion calculation. These limits are especially related to the detection of pupil center and the effects of pupil size changes. This article aims at (1) proposing a solution to analyze ocular torsion together with head roll using EyeLink II or similar equipment, (2) reviewing and adapting classical polar cross-correlation methods in order to improve the accuracy of torsion measurement, (3) providing a lower-cost method compared with the existing ones. Video sequences issued from the EyeLink II host computer monitor were recorded by means of a second computer equipped with a video acquisition card and converted into image sequences. Images were analyzed with algorithms of pupil center detection (median-based algorithm), torsion analysis (adapted polar cross-correlation method which takes into account pupil size variations) and marker tracking (head roll analysis). This method was tested on virtual eye images. Results are discussed with respect to other algorithms found in the literature.

  1. Playing level achieved, throwing history, and humeral torsion in Masters baseball players.

    PubMed

    Whiteley, Rod; Adams, Roger; Ginn, Karen; Nicholson, Leslie

    2010-09-01

    Humeral torsion is thought to be beneficial for throwing. To examine this hypothesis, the throwing and non-throwing arms of 84 Masters baseball players over 35 years of age were measured for humeral torsion, and the highest playing level they achieved and their playing history were recorded. Regression analyses were used to obtain predictors of the highest playing level achieved, throwing arm humeral torsion, and side-to-side difference in humeral torsion. Equations accounting for 36%, 46%, and 12% of the variance respectively were produced. Achieving representative level playing status was associated with the number of seasons played under 16 years of age and having greater throwing arm humeral retrotorsion. Throwing arm humeral retrotorsion was associated with non-throwing arm humeral retrotorsion and an increased number of seasons played before the age of 16 years. A model in which repeated throwing develops an adaptive unilateral bone torsion along with growth in baseball expertise is proposed. Thus dominant arm humeral retrotorsion is a predictor of highest baseball playing level achieved, which in turn is influenced by genetic endowment (as seen in the torsion of the non-throwing arm) and amount of throwing activity, particularly prior to the age of 16.

  2. Electrical and mechanical characteristics of fully transparent IZO thin-film transistors on stress-relieving bendable substrates

    NASA Astrophysics Data System (ADS)

    Park, Sukhyung; Cho, Kyoungah; Oh, Hyungon; Kim, Sangsig

    2016-10-01

    In this study, we report the electrical and mechanical characteristics of fully transparent indium zinc oxide (IZO) thin-film transistors (TFTs) fabricated on stress-relieving bendable substrates. An IZO TFT on a stress-relieving substrate can operate normally at a bending radius of 6 mm, while an IZO TFT on a normal plastic substrate fails to operate normally at a bending radius of 15 mm. A plastic island with high Young's modulus embedded on a soft elastomer layer with low Young's modulus plays the role of a stress-relieving substrate for the operation of the bent IZO TFT. The stress and strain distributions over the IZO TFT will be analyzed in detail in this paper.

  3. Predictive role of hematologic parameters in testicular torsion

    PubMed Central

    Umul, Mehmet; Altok, Muammer; Akyuz, Mehmet; İşoğlu, Cemal Selcuk; Uruc, Fatih; Aras, Bekir; Akbaş, Alpaslan; Baş, Ercan

    2015-01-01

    Purpose To evaluate the predictive role of the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), mean platelet volume (MPV), and platelet count (PLT) in the diagnosis of testicular torsion (TT) and testicular viability following TT. Materials and Methods We analyzed two study groups in this retrospective study: 75 patients with a diagnosis of TT (group 1) and 56 age-matched healthy subjects (group 2). We performed a complete blood count as a part of the diagnostic procedure, and NLR, PLR, MPV, and PLT values were recorded. We compared the patient and control groups in terms of these parameters. Then, TT patients were divided into two subgroups according to the time elapsed since the onset of symptoms. Subsequently, we evaluated the relationship between the duration of symptoms and these parameters. Results There were significant differences between groups 1 and 2 in NLR, PLR, and PLT (p<0.001 for all). There was no predictive role of MPV in the diagnosis of TT (p=0.328). We determined significantly high sensitivity and specificity levels for NLR in the prediction of TT diagnosis (84% and 92%, respectively). Furthermore, NLR was significantly related to the duration of symptoms in TT patients (p=0.01). Conclusions NLR may be a useful parameter in the diagnosis of TT. Furthermore, NLR may be used as a predictive factor for testicular viability following TT. PMID:25874047

  4. The self-similarity theory of high pressure torsion

    PubMed Central

    Beygelzimer, Yan; Toth, Laszlo S; Ivanisenko, Yulia

    2016-01-01

    Summary By analyzing the problem of high pressure torsion (HPT) in the rigid plastic formulation, we show that the power hardening law of plastically deformed materials leads to self-similarity of HPT, admitting a simple mathematical description of the process. The analysis shows that the main parameters of HPT are proportional to βq, with β being the angle of the anvil rotation. The meaning of the parameter q is: q = 0 for velocity and strain rate, q = 1 for shear strain and von Mises strain, q = n for stress, pressure and torque (n is the exponent of a power hardening law). We conclude that if the hardening law is a power law in a rotation interval β, self-similar regimes can emerge in HPT if the friction with the lateral wall of the die is not too high. In these intervals a simple mathematical description can be applied based on self-similarity. Outside these ranges, the plasticity problem still has to be solved for each value of β. The results obtained have important practical implications for the proper design and analysis of HPT experiments. PMID:27826500

  5. Observation of Intralaminar Cracking in the Edge Crack Torsion Specimen

    NASA Technical Reports Server (NTRS)

    Czabaj, Michael W.; Ratcliffe, James G.; Davidson, Barry D.

    2013-01-01

    The edge crack torsion (ECT) test is evaluated to determine its suitability for measuring fracture toughness associated with mode III delamination growth onset. A series of ECT specimens with preimplanted inserts with different lengths is tested and examined using nondestructive and destructive techniques. Ultrasonic inspection of all tested specimens reveals that delamination growth occurs at one interface ply beneath the intended midplane interface. Sectioning and optical microscopy suggest that the observed delamination growth results from coalescence of angled intralaminar matrix cracks that form and extend across the midplane plies. The relative orientation of these cracks is approximately 45 deg with respect to the midplane, suggesting their formation is caused by resolved principal tensile stresses arising due to the global mode-III shear loading. Examination of ECT specimens tested to loads below the level corresponding to delamination growth onset reveals that initiation of intralaminar cracking approximately coincides with the onset of nonlinearity in the specimen's force-displacement response. The existence of intralaminar cracking prior to delamination growth onset and the resulting delamination extension at an unintended interface render the ECT test, in its current form, unsuitable for characterization of mode III delamination growth onset. The broader implications of the mechanisms observed in this study are also discussed with respect to the current understanding of shear-driven delamination in tape-laminate composites.

  6. Ultrasonic rock sampling using longitudinal-torsional vibrations.

    PubMed

    Cardoni, Andrea; Harkness, Patrick; Lucas, Margaret

    2010-04-01

    In the last years several European and US space projects have been focused on the development of surface rovers for planetary missions, such as ExoMars and Mars Exploration Rovers. The main function of these vehicles consists of moving across planet surfaces, and drilling and retrieving samples for in situ analysis. Recent research has shown that drilling of rock materials can be achieved using axially oscillating tuned devices which, compared with conventional rotary drills, operate at lower power and highly reduced preload requirements. As a result, at present, ultrasonics is considered a very promising technology for exobiological prospecting. In this work, two novel ultrasonic rock samplers, both operating in a longitudinal-torsional composite mode, are proposed along with the conceptual design of a full coring apparatus, for preload delivery and core removal. To assess the penetration capability of the excited composite vibrations, preliminary drilling trials were conducted. Since sand constitutes a significant portion of the Martian surface, sandstone was used in the trials.

  7. The self-similarity theory of high pressure torsion.

    PubMed

    Beygelzimer, Yan; Kulagin, Roman; Toth, Laszlo S; Ivanisenko, Yulia

    2016-01-01

    By analyzing the problem of high pressure torsion (HPT) in the rigid plastic formulation, we show that the power hardening law of plastically deformed materials leads to self-similarity of HPT, admitting a simple mathematical description of the process. The analysis shows that the main parameters of HPT are proportional to β (q) , with β being the angle of the anvil rotation. The meaning of the parameter q is: q = 0 for velocity and strain rate, q = 1 for shear strain and von Mises strain, q = n for stress, pressure and torque (n is the exponent of a power hardening law). We conclude that if the hardening law is a power law in a rotation interval β, self-similar regimes can emerge in HPT if the friction with the lateral wall of the die is not too high. In these intervals a simple mathematical description can be applied based on self-similarity. Outside these ranges, the plasticity problem still has to be solved for each value of β. The results obtained have important practical implications for the proper design and analysis of HPT experiments.

  8. An analytical model of a longitudinal-torsional ultrasonic transducer

    NASA Astrophysics Data System (ADS)

    Al-Budairi, Hassan; Lucas, Margaret

    2012-08-01

    The combination of longitudinal and torsional (LT) vibrations at high frequencies finds many applications such as ultrasonic drilling, ultrasonic welding, and ultrasonic motors. The LT mode can be obtained by modifications to the design of a standard bolted Langevin ultrasonic transducer driven by an axially poled piezoceramic stack, by a technique that degenerates the longitudinal mode to an LT motion by a geometrical alteration of the wave path. The transducer design is developed and optimised through numerical modelling which can represent the geometry and mechanical properties of the transducer and its vibration response to an electrical input applied across the piezoceramic stack. However, although these models can allow accurate descriptions of the mechanical behaviour, they do not generally provide adequate insights into the electrical characteristics of the transducer. In this work, an analytical model is developed to present the LT transducer based on the equivalent circuit method. This model can represent both the mechanical and electrical aspects and is used to extract many of the design parameters, such as resonance and anti-resonance frequencies, the impedance spectra and the coupling coefficient of the transducer. The validity of the analytical model is demonstrated by close agreement with experimental results.

  9. Brownian Motion of a Torsion Pendulum Damped by Internal Friction.

    NASA Astrophysics Data System (ADS)

    Gonzalez, Gabriela Ines

    1995-01-01

    Brownian motion is a well known limit to precision experiments, and it is also going to be a limiting factor in the sensitivity of interferometric gravitational wave detectors. The power spectral density of Brownian motion depends dramatically on the strength and frequency dependence of the energy dissipation in the system of interest. We present here the measurement of Brownian motion of a simple oscillator, a torsion pendulum, where the energy losses are due to internal friction in the suspension fiber. We calculate from these measurements the power spectrum S _theta(f) of the Brownian motion, as well as other statistical functions defined in irreversible thermodynamics, such as the autocorrelation function and conditional probability distributions. We also present a measurement of internal friction as a function of frequency. With this and the physical parameters describing the pendulum, we use the fluctuation -dissipation theorem to calculate S_theta(f). . We then compare the prediction and measurement of S_theta(f), and show excellent agreement over a decade in frequency around the pendulum frequency. The spectrum S_theta(f) is not flat below resonance, and in fact follows a S_theta(f)~1/f law.

  10. Ring-Constraint High-Pressure Torsion Process

    NASA Astrophysics Data System (ADS)

    Joo, Soo-Hyun; Kim, Hyoung Seop

    2016-07-01

    In this study, a constraint ring around a workpiece was employed in order to develop back pressure in addition to a compressive die pressure in high-pressure torsion (HPT) process. The influence of the constraint ring during the HPT process was analyzed using the finite element method and experimental analyses. Greater back pressure was developed when a ring of a stronger material enveloped the workpiece. In the experiments, fracture of a brittle material [ e.g., La-based bulk metallic glass (BMG)], was limited even at large shear strain (~315) during the ring-constraint HPT (RC-HPT) process due to reduced tensile stress at the edge of the deforming BMG workpiece. Furthermore, the RC-HPT process had beneficial effects on powder consolidation and bonding. The RC-HPT process exhibited smaller loss of material than did the conventional semi-constrained HPT process. The Cu disk produced by the powder RC-HPT had smaller grain sizes because back pressure generated more dislocations and finer grain size in the Cu workpiece.

  11. Magnetomechanical effects under torsional strain in iron, cobalt and nickel

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Kriegermeier-Sutton, B. K.; Snyder, J. E.; Dennis, K. W.; McCallum, R. W.; Jiles, D. C.

    2001-10-01

    The change of magnetization as a function of applied torque has been investigated for cylindrical rods of 99.9% pure iron, cobalt and nickel. The relationship between the magnetomechanical effect and magnetostriction in these materials has also been investigated. Torque was applied with amplitude up to ±5 N m with no associated bending moment. The magnetic field near the sample surface was measured using a Hall effect sensor at the center of the sample. The results showed a linear dependence of this field on torque once the transient effects of the first few stress cycles had been overcome. The derivative of the surface circumferential magnetic field with respect to torque for a nickel rod was 19 A N -1 m -2. Cobalt and iron, on the other hand, showed smaller sensitivity to torsional stress, with changes less than 1 A N -1 m -2. The difference in behavior is due to the higher ratio of magnetostriction to anisotropy in nickel. Magnetostriction measurements were made and it was found that the piezomagnetic coefficient d, that is the slope of the magnetostriction curve d λ/d H, at low magnetic field is an important figure of merit in determining sensitivity of magnetization to torque. It is shown that the sensitivity of magnetic induction to stress d B/d σ is dependent on the ratio of magnetostriction to anisotropy.

  12. Rotational friction of dipolar colloids measured by driven torsional oscillations

    PubMed Central

    Steinbach, Gabi; Gemming, Sibylle; Erbe, Artur

    2016-01-01

    Despite its prominent role in the dynamics of soft materials, rotational friction remains a quantity that is difficult to determine for many micron-sized objects. Here, we demonstrate how the Stokes coefficient of rotational friction can be obtained from the driven torsional oscillations of single particles in a highly viscous environment. The idea is that the oscillation amplitude of a dipolar particle under combined static and oscillating fields provides a measure for the Stokes friction. From numerical studies we derive a semi-empirical analytic expression for the amplitude of the oscillation, which cannot be calculated analytically from the equation of motion. We additionally demonstrate that this expression can be used to experimentally determine the rotational friction coefficient of single particles. Here, we record the amplitudes of a field-driven dipolar Janus microsphere with optical microscopy. The presented method distinguishes itself in its experimental and conceptual simplicity. The magnetic torque leaves the local environment unchanged, which contrasts with other approaches where, for example, additional mechanical (frictional) or thermal contributions have to be regarded. PMID:27680399

  13. The Quadratic Spinor Lagrangian, Axial Torsion Current and Generalizations

    NASA Astrophysics Data System (ADS)

    Da Rocha, R.; Pereira, J. G.

    We show that the Einstein-Hilbert, the Einstein-Palatini, and the Holst actions can be derived from the Quadratic Spinor Lagrangian (QSL), when the three classes of Dirac spinor fields, under Lounesto spinor field classification, are considered. To each one of these classes, there corresponds an unique kind of action for a covariant gravity theory. In other words, it is shown to exist a one-to-one correspondence between the three classes of non-equivalent solutions of the Dirac equation, and Einstein-Hilbert, Einstein-Palatini, and Holst actions. Furthermore, it arises naturally, from Lounesto spinor field classification, that any other class of spinor field — Weyl, Majorana, flagpole, or flag-dipole spinor fields — yields a trivial (zero) QSL, up to a boundary term. To investigate this boundary term, we do not impose any constraint on the Dirac spinor field, and consequently we obtain new terms in the boundary component of the QSL. In the particular case of a teleparallel connection, an axial torsion one-form current density is obtained. New terms are also obtained in the corresponding Hamiltonian formalism. We then discuss how these new terms could shed new light on more general investigations.

  14. Torsional Oscillations Of A Magnetar With A Tangled Magnetic Field

    NASA Astrophysics Data System (ADS)

    van Eysden, Anthony

    2017-01-01

    Motivated by stability considerations and observational evidence, we argue that magnetars possess highly-tangled internal magnetic fields. We propose that the quasi-periodic oscillations (QPOs) seen to accompany giant flares can be explained as torsional modes supported by a tangled magnetic field, and we present a simple model that supports this hypothesis for SGR 1900+14. Taking the strength of the tangle as a free parameter, we find that the magnetic energy in the tangle must dominate that in the dipolar component by a factor of 14 to accommodate the observed 28 Hz QPO. Our simple model provides useful scaling relations for how the QPO spectrum depends on the bulk properties of the neutron star and the tangle strength. The energy density in the tangled field inferred for SGR 1900+14 renders the crust nearly dynamically irrelevant, a significant simplification for study of the QPO problem. The predicted spectrum is about three times denser than observed, which could be explained by preferential mode excitation or beamed emission. We emphasize that field tangling is needed to stabilize the magnetic field, so should not be ignored in treatment of the QPO problem.

  15. Combined torsional buckling of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lu, Y. J.; Wang, X.

    2006-08-01

    This paper reports the results of an investigation on combined torsional buckling of an individual multi-walled carbon nanotube (MWNT) under combined torque and axial loading. Here, a multiple shell model is adopted and the effect of van der Waals forces between two adjacent tubes is taken into account. According to the ratio of radius to thickness, MWNTs discussed in this paper are classified into three types: thin, thick and nearly solid. The critical shear stress and the combined buckling mode are calculated for three types of MWNTs under combined torque and axial loading. Results carried out show that the buckling mode (m, n) corresponding to the critical shear stress is unique, which is obviously different from the purely axial compression buckling of an individual MWNT. Numerical results also show that the critical shear stresses and the corresponding buckling modes of MWNTs under combined torque and axial loading are dependent on the axial loading form and the types of MWNTs. The new features and meaningful numerical results in the present work on combined buckling of MWNTs under combined torque and axial loading may be used as a useful reference for the designs of nano-drive devices and rotational actuators in which MWNTs act as basic elements.

  16. Understanding Solar Torsional Oscillations from Global Dynamo Models

    NASA Astrophysics Data System (ADS)

    Guerrero, G.; Smolarkiewicz, P. K.; de Gouveia Dal Pino, E. M.; Kosovichev, A. G.; Mansour, N. N.

    2016-09-01

    The phenomenon of solar “torsional oscillations” (TO) represents migratory zonal flows associated with the solar cycle. These flows are observed on the solar surface and, according to helioseismology, extend through the convection zone. We study the origin of the TO using results from a global MHD simulation of the solar interior that reproduces several of the observed characteristics of the mean-flows and magnetic fields. Our results indicate that the magnetic tension (MT) in the tachocline region is a key factor for the periodic changes in the angular momentum transport that causes the TO. The torque induced by the MT at the base of the convection zone is positive at the poles and negative at the equator. A rising MT torque at higher latitudes causes the poles to speed up, whereas a declining negative MT torque at the lower latitudes causes the equator to slow-down. These changes in the zonal flows propagate through the convection zone up to the surface. Additionally, our results suggest that it is the magnetic field at the tachocline that modulates the amplitude of the surface meridional flow rather than the opposite as assumed by flux-transport dynamo models of the solar cycle.

  17. Standing Torsional Waves in Fluid-Saturated Porous Circular Cylinder

    NASA Astrophysics Data System (ADS)

    Solorza, S.; Sahay, P. N.

    2002-12-01

    For dynamic measurement of elastic constants of a porous material saturated with viscous fluid when resonance-bar technique is applied, one also observes attenuation of the wave field. The current practice is to interpret it in terms of solid-viscosity by assuming a viscoelastic rheology for porous material. The likely mechanisms of attenuation in a fluid saturated porous material are: 1) motion of the fluid with respect to the solid frame and 2) viscous loss within the pore fluid. Therefore, it is appropriate to assume a poroelastic rheology and link the observed attenuation value to fluid properties and permeability. In the framework of poroelastic theory, the explicit formula linking attenuation to the properties of solid and fluid constituents and permeability are not worked out yet. In order to established such a link one has to workout solutions of appropriate boundary value problems in such a framework. Here, we have carried out the solution of boundary value problem associated with torsional oscillation of a finite poroelastic circular cylinder, casted in the framework of volume-averaged theory of poroelasticity. Analysing this solution by a perturbative approach we are able to develop explicit expressions for resonance frequency and attenuation for this mode of vibration. 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 porous frame due to the effect of the fluid-mass.

  18. Cyclic Axial-Torsional Deformation Behavior of a Cobalt-Base Superalloy

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1995-01-01

    The cyclic, high-temperature deformation behavior of a wrought cobalt-base super-alloy, Haynes 188, is investigated under combined axial and torsional loads. This is accomplished through the examination of hysteresis loops generated from a biaxial fatigue test program. A high-temperature axial, torsional, and combined axial-torsional fatigue database has been generated on Haynes 188 at 760 C. Cyclic loading tests have been conducted on uniform gage section tubular specimens in a servohydraulic axial-torsional test rig. Test control and data acquisition were accomplished with a minicomputer. The fatigue behavior of Haynes 188 at 760 C under axial, torsional, and combined axial-torsional loads and the monotonic and cyclic deformation behaviors under axial and torsional loads have been previously reported. In this paper, the cyclic hardening characteristics and typical hysteresis loops in the axial stress versus axial strain, shear stress ,versus engineering shear strain, axial strain versus engineering shear strain. and axial stress versus shear stress spaces are presented for cyclic in-phase and out-of-phase axial-torsional tests. For in-phase tests, three different values of the proportionality constant lambda (the ratio of engineering shear strain amplitude to axial strain amplitude, are examined, viz. 0.86, 1.73, and 3.46. In the out-of-phase tests, three different values of the phase angle, phi (between the axial and engineering shear strain waveforms), are studied, viz., 30, 60, and 90 degrees with lambda equals 1.73. The cyclic hardening behaviors of all the tests conducted on Haynes 188 at 760 C are evaluated using the von Mises equivalent stress-strain and the maximum shear stress-maximum engineering shear strain (Tresca) curves. Comparisons are also made between the hardening behaviors of cyclic axial, torsional, and combined in-phase (lambda = 1.73 and phi = 0) and out-of-phase (lambda = 1.73 and phi = 90') axial-torsional fatigue tests. These comparisons

  19. Constraints on torsion from the bosonic sector of Lorentz violation and magnetogenesis data

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2011-06-01

    A. Kostelecky et al. [Phys. Rev. Lett. 100 (2008) 111102], have shown that there is an exceptional sensitivity of spacetime torsion components by coupling it to fermions and constraining it to Lorentz violation. They obtain new constraints on torsion components down to the level of 10 GeV. Yet more recently, L.C. Garcia de Andrade [Phys. Lett. B 468 (2011) 28] has shown that the photon sector of Lorentz violation (LV) Lagrangian leads to linear non-standard Maxwell equations where the magnetic field decays slower giving rise to a seed for galactic dynamos. In this paper bounds are placed on torsion based on the magnetogenesis or the origin of magnetic fields in the universe. On a coherence scale of 10 kpc, galactic magnetic fields of the order of some μG yield a torsion primordial field of the order of K≈10 GeV. Just to give an idea of how tiny it is we mention that torsion limit in the Early universe yield K≈10 GeV had been obtained by V. de Sabbata and C. Sivaram. Good limits were also obtained by B.R. Heckel et al. [Phys. Rev. D 78 (2008) 092006]. In our case the advantage from astro-particle physics point of view, is that a very small seed torsion field is enough to seed galactic dynamo. C. Sivaram limit is obtained from a massive photon electrodynamics [L.C. Garcia de Andrade, C. Sivaram, Ap. Space Sci. 209 (1993) 109] where a gauge invariant electrodynamics is used. Dynamo stars data are able to raise this value of torsion up to 10 GeV at magnetar atmosphere. From these estimates one notices that they coincide with the ones obtained by A. Kostelecky et al., the difference being basically in the method. The ones here were obtained from magnetogenesis data while theirs were obtained from the Earth laboratory data from polarised electrons. Besides here one used the torsion derivatives while A. Kostelecky et al. uses the constant axial torsion tensor. Another fundamental distinction is that we use bosonic sector of the Lagrangian while they use mainly

  20. Integrated cantilever sensors with a torsional resonance mode for ultraresoluble on-the-spot bio/chemical detection

    NASA Astrophysics Data System (ADS)

    Jin, Dazhong; Li, Xinxin; Bao, Hanhan; Zhang, Zhixiang; Wang, Yuelin; Yu, Haitao; Zuo, Guomin

    2007-01-01

    Torsion-mode resonance is built in an integrated cantilever sensor for ultraresoluble detection of specifically bio/chemical mass adsorption. The superior mass resolution of the torsion-mode cantilever to a conventional bending-mode one is verified by energy-dissipation analysis and Q-factor simulation. With integrated transverse piezoresistance for frequency-shift signal readout and Lorentz force for resonance excitation, the torsion-mode sensor is optimally designed for high sensitivity. The microfabricated torsion-mode sensor is measured with a high close-loop Q factor in air. By Allan-variance analysis for the measured frequency stability, 23fg resolution is obtained for the torsion-mode sensor, which is much improved compared to the 313fg for the conventional flexure-mode sensor. The torsional sensor is used to recognize biotin-avidin specific combination, resulting in 443Hz frequency shift for 50μM streptavidin solution.