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Sample records for dna relieves torsional

  1. In the absence of writhe, DNA relieves torsional stress with localized, sequence-dependent structural failure to preserve B-form

    PubMed Central

    Randall, Graham L.; Zechiedrich, Lynn; Pettitt, B. Montgomery

    2009-01-01

    To understand how underwinding and overwinding the DNA helix affects its structure, we simulated 19 independent DNA systems with fixed degrees of twist using molecular dynamics in a system that does not allow writhe. Underwinding DNA induced spontaneous, sequence-dependent base flipping and local denaturation, while overwinding DNA induced the formation of Pauling-like DNA (P-DNA). The winding resulted in a bimodal state simultaneously including local structural failure and B-form DNA for both underwinding and extreme overwinding. Our simulations suggest that base flipping and local denaturation may provide a landscape influencing protein recognition of DNA sequence to affect, for examples, replication, transcription and recombination. Additionally, our findings help explain results from single-molecule experiments and demonstrate that elastic rod models are strictly valid on average only for unstressed or overwound DNA up to P-DNA formation. Finally, our data support a model in which base flipping can result from torsional stress. PMID:19586933

  2. In the Absence of Writhe, DNA Relieves Torsional Stress with Localized, Sequence-Dependent Structural Failure to Preserve B-form

    SciTech Connect

    Randall, Graham L.; Zechiedrich, E. L.; Pettitt, Bernard M.

    2009-09-01

    To understand how underwinding and overwinding the DNA helix affects its structure, we simulated 19 independent DNA systems with fixed degrees of twist using molecular dynamics in a system that does not allow writhe. Underwinding DNA induced spontaneous, sequence-dependent base flipping and local denaturation, while overwinding DNA induced the formation of Pauling-like DNA (P-DNA). The winding resulted in a bimodal state simultaneously including local structural failure and B-form DNA for both underwinding and extreme overwinding. Our simulations suggest that base flipping and local denaturation may provide a landscape influencing protein recognition of DNA sequence to affect, for examples, replication, transcription and recombination. Additionally, our findings help explain results from singlemolecule experiments and demonstrate that elastic rod models are strictly valid on average only for unstressed or overwound DNA up to P-DNA formation. Finally, our data support a model in which base flipping can result from torsional stress.

  3. Modeling DNA Thermodynamics under Torsional Stress

    PubMed Central

    Wang, Qian; Pettitt, B. Montgomery

    2014-01-01

    Negatively twisted DNA is essential to many biological functions. Due to torsional stress, duplex DNA can have local, sequence-dependent structural defects. In this work, a thermodynamic model of DNA was built to qualitatively predict the local sequence-dependent mechanical instabilities under torsional stress. The results were compared to both simulation of a coarse-grained model and experiment results. By using the Kirkwood superposition approximation, we built an analytical model to represent the free energy difference ΔW of a hydrogen-bonded basepair between the B-form helical state and the basepair opened (or locally melted) state, within a given sequence under torsional stress. We showed that ΔW can be well approximated by two-body interactions with its nearest-sequence-neighbor basepairs plus a free energy correction due to long-range correlations. This model is capable of rapidly predicting the position and thermodynamics of local defects in a given sequence. The result qualitatively matches with an in vitro experiment for a long DNA sequence (>4000 basepairs). The 12 parameters used in this model can be further quantitatively refined when more experimental data are available. PMID:24606942

  4. Modeling DNA thermodynamics under torsional stress.

    PubMed

    Wang, Qian; Pettitt, B Montgomery

    2014-03-01

    Negatively twisted DNA is essential to many biological functions. Due to torsional stress, duplex DNA can have local, sequence-dependent structural defects. In this work, a thermodynamic model of DNA was built to qualitatively predict the local sequence-dependent mechanical instabilities under torsional stress. The results were compared to both simulation of a coarse-grained model and experiment results. By using the Kirkwood superposition approximation, we built an analytical model to represent the free energy difference ΔW of a hydrogen-bonded basepair between the B-form helical state and the basepair opened (or locally melted) state, within a given sequence under torsional stress. We showed that ΔW can be well approximated by two-body interactions with its nearest-sequence-neighbor basepairs plus a free energy correction due to long-range correlations. This model is capable of rapidly predicting the position and thermodynamics of local defects in a given sequence. The result qualitatively matches with an in vitro experiment for a long DNA sequence (>4000 basepairs). The 12 parameters used in this model can be further quantitatively refined when more experimental data are available. PMID:24606942

  5. 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.

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

    PubMed

    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

  7. 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

  8. 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.

  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. Pain Relievers

    MedlinePlus

    Pain relievers are medicines that reduce or relieve headaches, sore muscles, arthritis, or other aches and pains. There ... also have a slightly different response to a pain reliever. Over-the-counter (OTC) medicines are good for ...

  11. Annealed Random Copolymer Model of the B-Z Transition in DNA: Torsional Responses

    PubMed Central

    Kwon, Ah-Young; Lee, Nam-Kyung; Hong, Seok-Cheol; Fierling, Julien; Johner, Albert

    2015-01-01

    Both in vivo and in vitro, specific sequences in double-stranded DNA can adopt the left-handed Z-form when underwound. Recently, the B-Z transition of DNA has been studied in detail in magnetic tweezers experiments by several groups. We present a theoretical description of this transition, based on an annealed random copolymer model. The transition of a switchable sequence is discussed as a function of energetic and geometric parameters of the B- and Z-forms, of the applied boundary conditions, and of the characteristics of the B-Z interface. We address a possible torsional softening upon the B-Z transition. The model can be also applied to other biofilaments with annealed torsional/flexural degrees of freedom. PMID:25992734

  12. 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.

  13. 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. PMID:26511644

  14. Chromatin regulates DNA torsional energy via topoisomerase II-mediated relaxation of positive supercoils

    PubMed Central

    Fernández, Xavier; Díaz-Ingelmo, Ofelia; Martínez-García, Belén; Roca, Joaquim

    2014-01-01

    Eukaryotic topoisomerases I (topo I) and II (topo II) relax the positive (+) and negative (−) DNA torsional stress (TS) generated ahead and behind the transcription machinery. It is unknown how this DNA relaxation activity is regulated and whether (+) and (−)TS are reduced at similar rates. Here, we used yeast circular minichromosomes to conduct the first comparative analysis of topo I and topo II activities in relaxing chromatin under (+) and (−)TS. We observed that, while topo I relaxed (+) and (−)TS with similar efficiency, topo II was more proficient and relaxed (+)TS more quickly than (−)TS. Accordingly, we found that the relaxation rate of (+)TS by endogenous topoisomerases largely surpassed that of (−)TS. We propose a model of how distinct conformations of chromatin under (+) and (−)TS may produce this unbalanced relaxation of DNA. We postulate that, while quick relaxation of (+)TS may facilitate the progression of RNA and DNA polymerases, slow relaxation of (−)TS may serve to favor DNA unwinding and other structural transitions at specific regions often required for genomic transactions. PMID:24859967

  15. DNAaseI-hypersensitive minichromosomes of SV40 possess an elastic torsional strain in DNA.

    PubMed Central

    Luchnik, A N; Bakayev, V V; Yugai, A A; Zbarsky, I B; Georgiev, G P

    1985-01-01

    Previously, we have shown that DNA in a small fraction (2-5%) of SV40 minichromosomes was torsionally strained and could be relaxed by treating minichromosomes with topoisomerase I. This fraction was enriched with endogeneous RNA polymerase II (Luchnik et al., 1982, EMBO J., 1, 1353). Here we show that one and the same fraction of SV40 minichromosomes is hypersensitive to DNAase I and is relaxable by topoisomerase I. Moreover, this fraction completely loses its hypersensitivity to DNAase I upon relaxation. The possibility that this fraction of minichromosomes can be represented by naked DNA is ruled out by the results of studying the kinetics of minichromosome digestion by DNAase I in comparison to digestion of pure SV40 DNA and by measuring the buoyant density of SV40 chromatin in equilibrium CsCl gradient. Our data obtained with SV40 minichromosomes may be relevant to the mechanism responsible for DNAase I hypersensitivity in the loops or domains of cellular chromatin. Images PMID:2987817

  16. 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

    2016-06-01

    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

  17. 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

  18. Sequence-specific transitions of the torsion angle gamma change the polar-hydrophobic profile of the DNA grooves: implication for indirect protein-DNA recognition.

    PubMed

    Zhitnikova, Mariia Yu; Boryskina, Olena P; Shestopalova, Anna V

    2014-01-01

    Variations of the shape and polarity of the DNA grooves caused by changes of the DNA conformation play an important role in the DNA readout. Despite the fact that non-canonical trans and gauche- conformations of the DNA backbone angle γ (O5'-C5'-C4'-C3') are frequently found in the DNA crystal structures, their possible role in the DNA recognition has not been studied systematically. In order to fill in this gap, we analyze the available high-resolution crystal structures of the naked and complexed DNA. The analysis shows that the non-canonical γ angle conformations are present both in the naked and bound DNA, more often in the bound vs. naked DNA, and in the nucleotides with the A-like vs. the B-like sugar pucker. The alternative angle γ torsions are more frequently observed in the purines with the A-like sugar pucker and in the pyrimidines with the B-like sugar conformation. The minor groove of the nucleotides with non-canonical γ angle conformation is more polar, while the major groove is more hydrophobic than in the nucleotides with the classical γ torsions due to variations in exposure of the polar and hydrophobic groups of the DNA backbone. The propensity of the nucleotides with different γ angle conformations to participate in the protein-nucleic acid contacts in the minor and major grooves is connected with their sugar pucker and sequence-specific. Our findings imply that the angle γ transitions contribute to the process of the protein-DNA recognition due to modification of the polar/hydrophobic profile of the DNA grooves. PMID:23998351

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

    PubMed

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

    2015-12-01

    Z-DNA duplexes are a particularly complicated test case for current force fields. We performed a set of explicit solvent molecular dynamics (MD) simulations with various AMBER force field parametrizations including our recent refinements of the ε/ζ and glycosidic torsions. None of these force fields described the ZI/ZII and other backbone substates correctly, and all of them underpredicted the population of the important ZI substate. We show that this underprediction can be attributed to an inaccurate potential for the sugar-phosphate backbone torsion angle β. We suggest a refinement of this potential, β(OL1), which was derived using our recently introduced methodology that includes conformation-dependent solvation effects. The new potential significantly increases the stability of the dominant ZI backbone substate and improves the overall description of the Z-DNA backbone. It also has a positive (albeit small) impact on another important DNA form, the antiparallel guanine quadruplex (G-DNA), and improves the description of the canonical B-DNA backbone by increasing the population of BII backbone substates, providing a better agreement with experiment. We recommend using β(OL1) in combination with our previously introduced corrections, εζ(OL1) and χ(OL4), (the combination being named OL15) as a possible alternative to the current β torsion potential for more accurate modeling of nucleic acids. PMID:26588601

  20. Positional dependence of transcriptional inhibition by DNA torsional stress in yeast chromosomes.

    PubMed

    Joshi, Ricky S; Piña, Benjamin; Roca, Joaquim

    2010-02-17

    How DNA helical tension is constrained along the linear chromosomes of eukaryotic cells is poorly understood. In this study, we induced the accumulation of DNA (+) helical tension in Saccharomyces cerevisiae cells and examined how DNA transcription was affected along yeast chromosomes. The results revealed that, whereas the overwinding of DNA produced a general impairment of transcription initiation, genes situated at <100 kb from the chromosomal ends gradually escaped from the transcription stall. This novel positional effect seemed to be a simple function of the gene distance to the telomere: It occurred evenly in all 32 chromosome extremities and was independent of the atypical structure and transcription activity of subtelomeric chromatin. These results suggest that DNA helical tension dissipates at chromosomal ends and, therefore, provides a functional indication that yeast chromosome extremities are topologically open. The gradual escape from the transcription stall along the chromosomal flanks also indicates that friction restrictions to DNA twist diffusion, rather than tight topological boundaries, might suffice to confine DNA helical tension along eukaryotic chromatin. PMID:20057354

  1. Positional dependence of transcriptional inhibition by DNA torsional stress in yeast chromosomes

    PubMed Central

    Joshi, Ricky S; Piña, Benjamin; Roca, Joaquim

    2010-01-01

    How DNA helical tension is constrained along the linear chromosomes of eukaryotic cells is poorly understood. In this study, we induced the accumulation of DNA (+) helical tension in Saccharomyces cerevisiae cells and examined how DNA transcription was affected along yeast chromosomes. The results revealed that, whereas the overwinding of DNA produced a general impairment of transcription initiation, genes situated at <100 kb from the chromosomal ends gradually escaped from the transcription stall. This novel positional effect seemed to be a simple function of the gene distance to the telomere: It occurred evenly in all 32 chromosome extremities and was independent of the atypical structure and transcription activity of subtelomeric chromatin. These results suggest that DNA helical tension dissipates at chromosomal ends and, therefore, provides a functional indication that yeast chromosome extremities are topologically open. The gradual escape from the transcription stall along the chromosomal flanks also indicates that friction restrictions to DNA twist diffusion, rather than tight topological boundaries, might suffice to confine DNA helical tension along eukaryotic chromatin. PMID:20057354

  2. Torsional flexibility of B-DNA as revealed by conformational analysis.

    PubMed Central

    Zhurkin, V B; Lysov, Y P; Florentiev, V L; Ivanov, V I

    1982-01-01

    The thermal fluctuations of a regular double helix belonging to the B-family were studied by means of atom-atomic potentials method. The winding angle fluctuation was found to be 2.4 degrees for poly(dA):poly(dT) and 3.0 degrees for poly(dG):poly(dC). The reasonable agreement of these estimations with those obtained experimentally reveals the essential role of the small-amplitude torsional vibrations of atoms in the mechanism of the double helix flexibility. The calculated equilibrium winding angle, tau 0, essentially depends on the degree of neutralization of phosphate groups, being about 35.5 degrees for the full neutralization. The deoxyribose pucker is closely related to the tau angle: while tau proceeds from 30 degrees to 45 degrees the pseudorotation phase angle, P, increases from 126 degrees to 164 degrees. Fluctuations of the angles TL and TW, which specify inclination of the bases to the helix axis, were evaluated to be 5 degrees-10 degrees. Possible correlation between conformational changes in the adjacent nucleotides is discussed. PMID:7071023

  3. Appendicular Torsion

    PubMed Central

    Dubhashi, Siddharth Pramod; Khadav, Bharat

    2016-01-01

    Torsion of the vermiform appendix is a rare condition detectable only at operation. It can be primary or secondary. This is a case report of 52-year-old female with 180° anti-clockwise rotation of the appendix. Torsion can further leads to strangulation and infarction of the organ. Appendicular torsion could be included in the differential diagnosis of pain in right iliac fossa. PMID:27013858

  4. 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.

  5. 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

  6. MedlinePlus: Pain Relievers

    MedlinePlus

    ... things you can do to help ease pain. Pain relievers are just one part of a pain treatment plan. Start Here Chronic Pain Medicines (American Academy of Family Physicians) Also in Spanish Pain Relievers: Understanding Your OTC Options (American Academy of Family ...

  7. Variable stiffness torsion springs

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  8. Variable stiffness torsion springs

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  9. Stress-relieved solder joints

    NASA Technical Reports Server (NTRS)

    Zemenick, C. J.

    1980-01-01

    Mechanical stress on solder joints is reduced by procedure for soldering electronic components to circuit boards. Procedure was developed for radio-frequency (RF) strip-line circuits, for which dimensions must be carefully controlled to minimize parasitic capacitance and inductance. Procedure consists of loosening component from its mounting after each lead is soldered relieving induced stresses before next soldering step.

  10. 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 ...

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

    MedlinePlus

    ... White House Lunch Recipes How Do Pain Relievers Work? KidsHealth > For Kids > How Do Pain Relievers Work? Print A A A Text Size en español ¿ ... the spot that hurts so much. Pain relievers work with your cells, your body's nerve endings, your ...

  12. Influence of DNA torsional rigidity on excision of 7,8-dihydro-8-oxo-2′-deoxyguanosine in the presence of opposing abasic sites by human OGG1 protein

    PubMed Central

    Barone, F.; Dogliotti, E.; Cellai, L.; Giordano, C.; Bjørås, M.; Mazzei, F.

    2003-01-01

    The human protein OGG1 (hOGG1) targets the highly mutagenic base 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-oxodG) and shows a high specificity for the opposite DNA base. Abasic sites can arise in DNA in close opposition to 8-oxodG either during repair of mismatched bases (i.e. 8-oxodG/A mismatches) or, more frequently, as a consequence of ionizing radiation exposure. Bistranded DNA lesions may remain unrepaired and lead to cell death via double-strand break formation. In order to explore the role of damaged-DNA dynamics in recognition/excision by the hOGG1 repair protein, specific oligonucleotides containing an 8-oxodG opposite an abasic site, at different relative distances on the complementary strand, were synthesized. Rotational dynamics were studied by means of fluorescence polarization anisotropy decay experiments and the torsional elastic constant as well as the hydrodynamic radius of the DNA fragments were evaluated. Efficiency of excision of 8-oxodG was tested using purified human glycosylase. A close relation between the twisting flexibility of the DNA fragment and the excision efficiency of the oxidative damage by hOGG1 protein within a cluster was found. PMID:12655006

  13. 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 ...

  14. Torsion-Mediated Interaction between Adjacent Genes

    PubMed Central

    Meyer, Sam; Beslon, Guillaume

    2014-01-01

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

  15. A fusional anomaly of the epididymis associated with recurrent testicular torsion.

    PubMed

    Aminu, Sani; Syed, Kamran; Gunendran, Thiru; Young, Graham

    2012-01-01

    A 31-year-old man with recurrent testicular torsion and infertility was found to have a fusional anomaly of the epididymis on scrotal exploration in which only the head of epididymis was attached to the testis, while the body and tail were completely free. He had bilateral orchidopexy, which relieved pain and recurrent torsion. He was then referred for fertility treatment. Literature search has shown that infertility is more associated with congenital anomalies of the epididymis and not with recurrent torsions. PMID:24578928

  16. Penile degloving and dorsal dartos flap rotation approach for the management of isolated penile torsion

    PubMed Central

    Aykaç, Aykut; Baran, Özer; Yapıcı, Onur; Aygün, Bülent Alper; Aydın, Cemil; Çakan, Murat

    2016-01-01

    Objective Penile torsion is a counterclockwise rotational anomaly of the penile shaft or glans. We aimed to evaluate the outcomes of penile degloving and dorsal dartos flap rotation used for the repair of isolated penil torsion. Material and methods During evaluation of the patients admitted to our polyclinic for circumcision between January 2013-December 2014, 5 cases of isolated penile torsion were determined. Following the circumcision procedure performed with bipolar cautery, patients undergoing penile degloving were checked whether penile torsion was relieved or not. In case of insufficient improvement, torsion was corrected with application of dorsal dartos flap. Penile torsion was corrected with dartos flap in 2, and penile degloving in 3 cases. Results The mean age of the patients was 5.6 years (4–7), and the mean operative time 12 minutes (7–20), respectively. The mean operation time was 17.5 (15–20) minutes and 8.3 (7–10) minutes in the dorsal dartos flap and penile degloving groups, respectively. The preoperative mean degree of penile torsion was 50° (30°–70°). The mean degree of torsion was 65° and 40° in the dorsal dartos and penile degloving groups, respectively. During the postoperative follow up, 1 case of residual torsion (<10°) was observed in the dorsal dartos flap group. Residual torsion was not observed in other patients. Conclusion Exploration for isolated cases of penile torsion during the circumcision procedure should not be overlooked. Successful results can be obtained with penile degloving and dartos flap rotation in cases with low and moderate torsion. PMID:27011878

  17. 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.

  18. Topical Pain Relievers May Cause Burns

    MedlinePlus

    ... For Consumers Home For Consumers Consumer Updates Topical Pain Relievers May Cause Burns Share Tweet Linkedin Pin it ... ts If you've ever rubbed a topical pain reliever—a cream, gel or other product applied to ...

  19. 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. PMID:26274421

  20. Torsional Ratcheting Actuating System

    SciTech Connect

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

    2000-01-24

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

  1. 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.

  2. Femtosecond torsional relaxation

    NASA Astrophysics Data System (ADS)

    Clark, J.; Nelson, T.; Tretiak, S.; Cirmi, G.; Lanzani, G.

    2012-03-01

    Molecular conformational reorganization following photon absorption is a fundamental process driving reactions such as the cis-trans isomerization at the heart of the primary step of vision and can be exploited for switching in artificial systems using photochromics. In general, conformational change occurs on a timescale defined by the energy of the main vibrational mode and the rate of energy dissipation. Typically, for a conformational change such as a twist around the backbone of a conjugated molecule, this occurs on the tens of picoseconds timescale. However, here we demonstrate experimentally that in certain circumstances the molecule, in this case an oligofluorene, can change conformation over two orders of magnitude faster (that is sub-100fs) in a manner analogous to inertial solvent reorganization demonstrated in the 1990s. Theoretical simulations demonstrate that non-adiabatic transitions during internal conversion can efficiently convert electronic potential energy into torsional kinetic energy, providing the `kick' that prompts sub-100fs torsional reorganization.

  3. Pedicle torsion of ovarian cyst and acupuncture--a case report.

    PubMed

    Qu, Fan; Zhou, Jue

    2006-09-01

    A case history is reported of a patient who presented with acute pedicle torsion in a left ovarian cyst, which had been diagnosed seven months previously. The diagnosis was established by sonography. She declined surgery for personal reasons, and was treated with acupuncture. Her pain was successfully relieved, and she continued to be observed. The acupuncture was repeated daily for 15 days, after which time repeat sonography showed reduction in size of the cyst, and no torsion of the pedicle. No relapse had occurred at 16 months follow up. PMID:17013361

  4. [Development of cough-relieving herbal teas].

    PubMed

    Puodziūniene, Gene; Janulis, Valdimaras; Milasius, Arvydas; Budnikas, Vytautas

    2005-01-01

    Cough-relieving medicinal herbs in tea are used from ancient times. Mucilage present in them or secretion produced under the influence of the active substances covers the oral and throat mucosa soothing its irritability and relieving dry, tiresome cough. It is known that the mixtures of medicinal herbs (Specias) have a complex influence on the human organism and the rational combination of medicinal herbs can improve their curative action and decrease the undesirable side effects. Having summarized the properties of those medicinal herbs we decided to create two formulations of cough-relieving herbal tea. The first formulation consists of marshmallow roots, liquorice roots and lime flowers, the second -- of marshmallow roots, Iceland moss and lime flowers. The methods for identification and assay of the active substances in the compounds were applied. The purity of the mixtures was regulated by limitation of the loss on drying, total ash, microbial contamination, contamination with radionuclides, heavy metals, pesticides and foreign matter. The expiry date of both cough-relieving herbal teas was approved to be 2 years. PMID:15998989

  5. 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.

  6. Testicular torsion: A surgical emergency

    SciTech Connect

    Prater, J.M.; Overdorf, B.S. )

    1991-09-01

    Testicular torsion is caused by twisting of the spermatic cord, which results in compromised testicular blood flow. The degree of ischemic injury is determined by the severity of arterial compression and the interval between the onset of symptoms and surgical intervention. Torsion usually occurs at puberty, and an anatomic defect known as bell-clapper deformity is usually present. Typical symptoms include acute scrotal pain with associated nausea and vomiting. Up to one-half of patients report previous similar episodes. On examination, the testis is high-riding, tender, swollen and firm. Testicular scan or Doppler ultrasound examination can be helpful in distinguishing torsion from acute epididymitis. Prompt surgical treatment is indicated to reduce the torsion, and bilateral orchiopexy is performed to prevent recurrence. Exocrine function, as determined by semen analysis, is often abnormal after unilateral torsion. 25 references.

  7. Torsional sensing of small-molecule binding using magnetic tweezers.

    PubMed

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

    2010-11-01

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

  8. Torsion Tests of Tubes

    NASA Technical Reports Server (NTRS)

    Stang, Ambrose H; Ramberg, Walter; Back, Goldie

    1937-01-01

    This report presents the results of tests of 63 chromium-molybdenum steel tubes and 102 17st aluminum-alloy tubes of various sizes and lengths made to study the dependence of the torsional strength on both the dimensions of the tube and the physical properties of the tube material. Three types of failure are found to be important for sizes of tubes frequently used in aircraft construction: (1) failure by plastic shear, in which the tube material reached its yield strength before the critical torque was reached; (2) failure by elastic two-lobe buckling, which depended only on the elastic properties of the tube material and the dimensions of the tube; and (3) failure by a combination of (1) and (2) that is, by buckling taking place after some yielding of the tube material.

  9. Saccular impact on ocular torsion.

    PubMed

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

    1996-01-01

    When someone is tilted laterally, the shear force on the maculae of the utriculus and the sacculus is described by the sine and the cosine of the angle of tilt, respectively. So both the sacculus and the utriculus are stimulated, but in the literature, ocular torsion is normally attributed to utricular function alone (and, thus, seen as a response to y-axis linear acceleration). However, on the base of a series of experiments on a tilt chair, a linear track, human centrifuges, and during parabolic flights, we conclude that the sacculus contributes to ocular torsion as well (there is a response to z-axis linear acceleration). The data suggest that the ratio of the utricular and saccular impact on ocular torsion is 3:1. The utriculus generates conjugate and the sacculus disjunctive torsional eye movements. PMID:8886354

  10. Torsional vibration of aircraft engines

    NASA Technical Reports Server (NTRS)

    Lurenbaum, Karl

    1932-01-01

    Exhaustive torsional-vibration investigations are required to determine the reliability of aircraft engines. A general outline of the methods used for such investigations and of the theoretical and mechanical means now available for this purpose is given, illustrated by example. True vibration diagrams are usually obtained from vibration measurements on the completed engine. Two devices for this purpose and supplementing each other, the D.V.L. torsiograph and the D.V.L. torsion recorder, are described in this report.

  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. 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.

  13. The Effect of Torsion-Torsion Interactions on the Tunneling Split Torsional Ground State.

    NASA Astrophysics Data System (ADS)

    Cameron, Ian George

    In NMR studies of methyl groups it is normally assumed that the effects of inter-methyl group interactions (torsion-torsion interactions) are negligible. This is probably a reasonable assump- tion at high temperatures(, )(>50K), however, for lower temperatures this is no longer the case. This is clearly demonstrated with tetra- methylsilane (TMS) for which several important effects of torsion-torsion interactions are reported. The spin lattice relaxtion time, T(,1), was measured as a function of the Larmor frequency at several temperatures and it is shown that the observed recovery can be characterized by two exponential contributions. As anticipated, the frequency dependence of T(,ZT)('-1), the recovery rate for the faster of the two contributing processes, exhibited resonant-like peaks. In other ways, however, these results deviate quite substantially from the behavior expected. Firstly, the hindering potential experienced by each methyl group in TMS is perturbed by the other three methyl groups in the molecule. This leads to the appearance of four resonant peaks in the frequency dependence of T(,ZT)('-1) instead of just two. A perturbation calculation is presented to support this interpretation. Secondly, the contribu- tion to the measured linewidths from lifetime broadening, which dominates at high temperatures, becomes negligible at low tem- peratures compared with the underlying "inherent" width of the tunneling lines. We associate this inherent width with a relatively narrow ((TURN)1 MHz), quasi-continuous distribution of tunneling split- tings which occurs as a result of partially averaged torsion-torsion interactions. Thirdly, the intensity of the peaks, which is expected to be temperature independent, drops sharply as the temperature is lowered. This is a clear indication of the formation of a band of tunneling states of low temperatures where torsion-torsion interactions are strong.

  14. Hypersymplectic structures with torsion on Lie algebroids

    NASA Astrophysics Data System (ADS)

    Antunes, P.; Nunes da Costa, J. M.

    2016-06-01

    Hypersymplectic structures with torsion on Lie algebroids are investigated. We show that each hypersymplectic structure with torsion on a Lie algebroid determines three Nijenhuis morphisms. From a contravariant point of view, these structures are twisted Poisson structures. We prove the existence of a one-to-one correspondence between hypersymplectic structures with torsion and hyperkähler structures with torsion. We show that given a Lie algebroid with a hypersymplectic structure with torsion, the deformation of the Lie algebroid structure by any of the transition morphisms does not affect the hypersymplectic structure with torsion. We also show that if a triplet of 2-forms is a hypersymplectic structure with torsion on a Lie algebroid A, then the triplet of the inverse bivectors is a hypersymplectic structure with torsion for a certain Lie algebroid structure on the dual A∗, and conversely. Examples of hypersymplectic structures with torsion are included.

  15. Stress-relieving interlayers for bituminous resurfacings

    NASA Astrophysics Data System (ADS)

    Frederick, D. A.

    1984-04-01

    The effectiveness of stress relieving interlayers (SRIs) in reducing reflective cracking in bituminous overlays on flexible pavements was investigated. SRI test sections were installed in 1980 and 1981 at five locations comprised of both 1 and 2-1/2 in overlays. Before construction, cracks were mapped in detail and deflection was measured to determine causes of cracking. SRIs tested included full width nonwoven and woven fabrics, rubberized asphalt surface treatments, reinforced rubberized asphalt strips, and composite fiberglass-asphalt binder systems. Construction of these test installations is summarized. Results of annual surveys have yet to prove conclusively the value of using these materials or their comparative effectiveness.

  16. Torsion Stiffness of a Protein Pair Determined by Magnetic Particles

    PubMed Central

    Janssen, X.J.A.; van Noorloos, J.M.; Jacob, A.; van IJzendoorn, L.J.; de Jong, A.M.; Prins, M.W.J.

    2011-01-01

    We demonstrate the ability to measure torsion stiffness of a protein complex by applying a controlled torque on a magnetic particle. As a model system we use protein G bound to an IgG antibody. The protein pair is held between a magnetic particle and a polystyrene substrate. The angular orientation of the magnetic particle shows an oscillating behavior upon application of a rotating magnetic field. The amplitude of the oscillation increases with a decreasing surface coverage of antibodies on the substrate and with an increasing magnitude of the applied field. For decreasing antibody coverage, the torsion spring constant converges to a minimum value of 1.5 × 103 pN·nm/rad that corresponds to a torsion modulus of 4.5 × 104 pN·nm2. This torsion stiffness is an upper limit for the molecular bond between the particle and the surface that is tentatively assigned to a single protein G–IgG protein pair. This assignment is supported by interpreting the measured stiffness with a simple mechanical model that predicts a two orders of magnitude larger stiffness for the protein G–IgG complex than values found for micrometer length dsDNA. This we understand from the structural properties of the molecules, i.e., DNA is a long and flexible chain-like molecule, whereas the antibody-antigen couple is orders of magnitude smaller and more globular in shape due to the folding of the molecules. PMID:21539795

  17. Propagating torsion in the Einstein frame

    SciTech Connect

    Poplawski, Nikodem J.

    2006-11-15

    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.

  18. Constraining torsion with Gravity Probe B

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

    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. 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.

  20. Torsional vibration isolator and method

    SciTech Connect

    Allen, C.A.; Durrett, V.D.

    1986-10-21

    This patent describes a multicylinder internal combustion engine having a rotatable crankshaft and a rotatable flywheel which together define an inertial system rotating about a predetermined axis of rotation. An improvement is described here which facilitates avoiding destructive effects on the crankshaft of stress induced by torsional vibration. The method comprises an elastomeric annulus coupling means operatively interposed between the crankshaft and flywheel for coupling the crankshaft and flywheel together for rotation of the flywheel with the crankshaft. The coupling means has a torsional spring rate of less than 20,000 in lb/radian effective to permit substantial angular displacement between the flywheel and the crankshaft for isolating the rotating inertia of the flywheel from the rotating inertia of the crankshaft after engine startup. The coupling means avoids dampening while preventing torsional vibration from being transferred between the flywheel and the crankshaft.

  1. 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.

  2. Imaging soft matters in water with torsional mode atomic force microscopy.

    PubMed

    Hwang, Ing-Shouh; Yang, Chih-Wen; Su, Ping-Hsiang; Hwu, En-Te; Liao, Hsien-Shun

    2013-12-01

    We have developed a high-sensitivity atomic force microscopy (AFM) mode operated in aqueous environment based on the torsional resonance of the cantilever. It is found that the torsional mode can achieve a good spatial resolution even with a relatively large tip. We have used this mode to image different soft materials in water, including DNA molecules and purple membrane. High-resolution images of purple membrane can be obtained at a relatively low ion concentration under a long-range electrostatic force. Thus the torsional mode allows investigators to probe surface structures and their properties under a wide range of solution conditions. PMID:22939703

  3. Flexural Torsional Guided Wave Pipe Inspection

    NASA Astrophysics Data System (ADS)

    Sun, Z.; Zhang, L.; Rose, J. L.

    2006-03-01

    Based on the flexural torsional guided wave theory and its focusing technique, this paper demonstrates the defect detection capability of flexural torsional guided waves on multiple defects with different shapes and axial, circumferential locations in pipe.

  4. Can a macroscopic gyroscope feel torsion

    NASA Technical Reports Server (NTRS)

    Stoeger, W. R.; Yasskin, P. B.

    1979-01-01

    We demonstrate that for a large class of Lagrangian-based torsion theories a macroscopic gyroscope is insensitive to the torsion field: there can be no coupling of the torsion to the gyroscope's angular momentum of rotation. To detect torsion a polarized system with a net elementary particle spin is needed. These conclusions are evident from the conservation laws, which form the basis for deriving the equations of motion.

  5. Torsion and buckling of open sections

    NASA Technical Reports Server (NTRS)

    Wagner, H; Pretschner, W

    1936-01-01

    Following an abstract of the well-known theory of torsion in compression, the writers give directions for the practical calculation of the values of C(sub BT) (resistance to flexure and torsion) and i(sub SP(exp 2)), which determine the torsion. The second part treats the experiments in support of the theory of torsion of plain and flanged angle sections.

  6. Torsional directed walks, entropic elasticity, and DNA twist stiffness

    PubMed Central

    Moroz, J. David; Nelson, Philip

    1997-01-01

    DNA and other biopolymers differ from classical polymers because of their torsional stiffness. This property changes the statistical character of their conformations under tension from a classical random walk to a problem we call the “torsional directed walk.” Motivated by a recent experiment on single lambda-DNA molecules [Strick, T. R., Allemand, J.-F., Bensimon, D., Bensimon, A. & Croquette, V. (1996) Science 271, 1835–1837], we formulate the torsional directed walk problem and solve it analytically in the appropriate force regime. Our technique affords a direct physical determination of the microscopic twist stiffness C and twist-stretch coupling D relevant for DNA functionality. The theory quantitatively fits existing experimental data for relative extension as a function of overtwist over a wide range of applied force; fitting to the experimental data yields the numerical values C = 120 nm and D = 50 nm. Future experiments will refine these values. We also predict that the phenomenon of reduction of effective twist stiffness by bend fluctuations should be testable in future single-molecule experiments, and we give its analytic form. PMID:9405627

  7. The torsional and rotation-torsion spectra of CD2HOH

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. Depletion of intracellular polyamines relieves inward rectification of potassium channels.

    PubMed Central

    Shyng, S L; Sha, Q; Ferrigni, T; Lopatin, A N; Nichols, C G

    1996-01-01

    Two different approaches were used to examine the in vivo role of polyamines in causing inward rectification of potassium channels. In two-microelectrode voltage-clamp experiments, 24-hr incubation of Xenopus oocytes injected with 50 nl of difluoromethylornithine (5 mM) and methylglyoxal bis(guanylhydrazone) (1 mM) caused an approximate doubling of expressed Kir2.1 currents and relieved rectification by causing an approximately +10-mV shift of the voltage at which currents are half-maximally inhibited. Second, a putrescine auxotrophic, ornithine decarboxylase-deficient Chinese hamster ovary (O-CHO) cell line was stably transfected with the cDNA encoding Kir2.3. Withdrawal of putrescine from the medium led to rapid (1-day) loss of the instantaneous phase of Kir2.3 channel activation, consistent with a decline of intracellular putrescine levels. Four days after putrescine withdrawal, macroscopic conductance, assessed using an 86Rb+ flux assay, was approximately doubled, and this corresponded to a +30-mV shift of V1/2 of rectification. With increasing time after putrescine withdrawal, there was an increase in the slowest phase of current activation, corresponding to an increase in the spermine-to-spermidine ratio over time. These results provide direct evidence for a role of each polyamine in induction of rectification, and they further demonstrate that in vivo modulation of rectification is possible by manipulation of polyamine levels using genetic and pharmacological approaches. PMID:8876254

  14. Re-torsion of the ovaries.

    PubMed

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

    2015-03-01

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

  15. 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.

  16. Cosmology in Poincaré gauge gravity with a pseudoscalar torsion

    NASA Astrophysics Data System (ADS)

    Lu, Jianbo; Chee, Guoying

    2016-05-01

    A cosmology of Poincar é gauge theory is developed, where several properties of universe corresponding to the cosmological equations with the pseudoscalar torsion function are investigated. The cosmological constant is found to be the intrinsic torsion and curvature of the vacuum universe and is derived from the theory naturally rather than added artificially, i.e. the dark energy originates from geometry and includes the cosmological constant but differs from it. The cosmological constant puzzle, the coincidence and fine tuning problem are relieved naturally at the same time. By solving the cosmological equations, the analytic cosmological solution is obtained and can be compared with the ΛCDM model. In addition, the expressions of density parameters of the matter and the geometric dark energy are derived, and it is shown that the evolution of state equations for the geometric dark energy agrees with the current observational data. At last, the full equations of linear cosmological perturbations and the solutions are obtained.

  17. An analysis of traction drive torsional stiffness

    NASA Technical Reports Server (NTRS)

    Rohn, D. A.; Loewenthal, S. H.

    1983-01-01

    The tangential compliance of elastic bodies in concentrated contact applied to traction drive elements to determine their torsional stiffness was analyzed. Static loading and rotating conditions are considered. The effects of several design variables are shown. The theoretical torsional stiffness of a fixed ratio multiroller drive is computed and compared to experimental values. It is shown that the torsional compliance of the traction contacts themselves is a relatively small portion of the overall drive system compliance.

  18. Empirical formula of crustal torsional oscillations

    NASA Astrophysics Data System (ADS)

    Sotani, Hajime

    2016-02-01

    Crustal torsional oscillations depend on not only crust properties but also the stellar mass and radius. Thus, one could extract stellar information by identifying the observed frequencies of stellar oscillations with the crustal torsional oscillations. Owing to the confinement of torsional oscillations inside the crust region of neutron stars, we successfully derive an empirical formula for the fundamental crustal torsional oscillations as a function of the stellar mass, radius, the so-called slope parameter of the nuclear symmetry energy, and the angular index of oscillations, with which one can estimate the frequencies with high accuracy. This empirical formula could be valuable in both the astrophysics and nuclear physics communities.

  19. Cellar: Detail of paired relieving arch and remains of herringbone ...

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

    Cellar: Detail of paired relieving arch and remains of herringbone brick pattern from earlier cooking fireplace at back, southeast wall looking southeast - Kingston-Upon-Hill, Kitts Hummock Road, Dover, Kent County, DE

  20. 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

  1. Review Suggests Safe, Effective Ways to Relieve Pain Without Meds

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_160744.html Review Suggests Safe, Effective Ways to Relieve Pain Without ... appear to be effective, according to a new review. Millions of Americans seek pain relief through such ...

  2. 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

  3. Results of experimental tests in the MSFC 14 x 14 inch trisonic wind tunnel on a .004 scale model space shuttle integrated vehicle 5 (model 77-O, 74-TS) to relieve wing loads during ascent (IA71)

    NASA Technical Reports Server (NTRS)

    Allen, E. C.

    1975-01-01

    Results are presented for the 0.004-scale orbiter, external tank, and solid rocket boosters combined as an integrated vehicle in a trisonic wind tunnel at mach numbers from 0.6 to 2.0. The primary test objective was to determine the effectiveness of several methods in relieving the Orbiter wing bending and torsion loads and moments during launch. Effects of several midwing spoilers, termed flipper doors, and Orbiter/external tank incidence were investigated. Photographs are included.

  4. Torsion of Noncircular Composite Cylinders

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  5. Torsion Profiling of Proteins Using Magnetic Particles

    PubMed Central

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

    2013-01-01

    We report a method to profile the torsional spring properties of proteins as a function of the angle of rotation. The torque is applied by superparamagnetic particles and has been calibrated while taking account of the magnetization dynamics of the particles. We record and compare the torsional profiles of single Protein G-Immunoglobulin G (IgG) and IgG-IgG complexes, sandwiched between a substrate and a superparamagnetic particle, for torques in the range between 0.5 × 103 and 5 × 103 pN·nm. Both molecular systems show torsional stiffening for increasing rotation angle, but the elastic and inelastic torsion stiffnesses are remarkably different. We interpret the results in terms of the structural properties of the molecules. The torsion profiling technique opens new dimensions for research on biomolecular characterization and for research on bio-nanomechanical structure-function relationships. PMID:23473490

  6. 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.

  7. Optically probing torsional superelasticity in spider silks

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  8. 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.

  9. Torsional oscillations of strange stars

    NASA Astrophysics Data System (ADS)

    Mannarelli, Massimo

    2014-11-01

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

  10. Torsional fatigue of aramid fibers

    SciTech Connect

    Kawabata, S.; Sera, M.

    1993-12-31

    An experimental investigation on the shear fatigue process of aramid fibers is presented. Repeated cycles of the torsional deformation are applied on the aramid single fiber and the reduction of the shear modulus of the fiber with an increasing number of the cycles is observed for different strain amplitudes. It has been found that the reduction process of the shear modulus with an increasing number of the repeated cycles depends on the strain amplitude and the effect of the number of cycles is equivalent to that of the strain amplitude on the modulus reduction and they may be superposed like the time-temperature equivalence superposition observed in the viscoelasticity of amorphous polymeric solids. From this relation, the life prediction for the long term use of aramid fibers becomes possible by using this superimposed relation. A simple rate process theory is applied to interpret this fatigue process and to derive the equation for predicting the life cycle number of the loading.

  11. Torsion phenomenology at the CERN LHC

    SciTech Connect

    Belyaev, A. S.; Shapiro, I. L.; Vale, M. A. B. do

    2007-02-01

    We explore the potential of the CERN Large Hadron Collider (LHC) to test the dynamical torsion parameters. The form of the torsion action can be established from the requirements of consistency of effective quantum field theory. The most phenomenologically relevant part of the torsion tensor is dual to a massive axial vector field. This axial vector has geometric nature, that means it does not belong to any representation of the gauge group of the SM extension or GUT theory. At the same time, torsion should interact with all fermions, that opens the way for the phenomenological applications. We demonstrate that LHC collider can establish unique constraints on the interactions between fermions and torsion field considerably exceeding present experimental lower bounds on the torsion couplings and its mass. It is also shown how possible nonuniversal nature of torsion couplings due to the renormalization group running between the Planck and TeV energy scales can be tested via the combined analysis of Drell-Yan and tt production processes.

  12. Euler angles as torsional flat spaces

    NASA Astrophysics Data System (ADS)

    Trejo-Mandujano, Hector A.

    In this work we use general tensor calculus to compare the geodesic equation of motion and Newton's first law for force-free classical systems that are described by an arbitrary number of generalized coordinates in spaces with and without torsion. We choose as objects of study the flat torsional Euler angle metric spaces for rigid rotators. We tested the equivalence of the two motion equations using computational software that allowed algebraic manipulation. The main result is that the equivalence only holds for torsion-free spaces, and for isotropic force-free rotators. We present analytical calculations for the isotropic case and computational results for the general case.

  13. 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.

  14. Observation of coronal loop torsional oscillation

    NASA Astrophysics Data System (ADS)

    Zaqarashvili, T. V.

    2003-02-01

    We suggest that the global torsional oscillation of solar coronal loop may be observed by the periodical variation of a spectral line width. The amplitude of the variation must be maximal at the velocity antinodes and minimal at the nodes of the torsional oscillation. Then the spectroscopic observation as a time series at different heights above the active region at the solar limb may allow to determine the period and wavelength of global torsional oscillation and consequently the Alfvén speed in corona. From the analysis of early observation (Egan & Schneeberger \\cite{egan}) we suggest the value of coronal Alfvén speed as ~ 500 km s-1.

  15. Testicular torsion in the older patient

    SciTech Connect

    Perry, S.; Hoopingarner, D.; Askins, D.

    1983-05-01

    A 40-year-old man presented with severe right-sided scrotal pain and was proven to have a 720-degree right testicular torsion. Fewer than 50 documented cases of testicular torsion have been reported in men over the age of thirty. The anatomical predisposition for torsion generally selects these individuals early in life. Rapid diagnosis allowed for surgical correction and testicular salvage. We outline an expedient diagnostic approach for these difficult cases with use of the Doppler ultrasound and the technetium (99mTc) testicular scan.

  16. Considerations regarding the stress relieving in a special product

    NASA Astrophysics Data System (ADS)

    Axinte, T.; Vladu, G.

    2015-11-01

    The special product has a steel bearing structure located inside the shoulders and it is fitted with a steel cylinder loaded by an internal pressure pi. The value of the maximum internal pressure is high, at limit being equal to the allowable stress (σa = pi), where pi = 3000 MPa. The uniform stresses decrease if there is an external pressure applied on the cylinder. Therefore, it must be produced external pressure in order to reduce the stress ctmax., in other words to achieve a relieving operation. The external diameter of the internal tube is larger than the internal diameter of the external tube. In the normal temperature conditions these two cylinders cannot be assembled. After it is heated up, expanded cylinder is mounted on the internal cylinder and after the quenching, on the contact surface it appears a relieving pressure p. We are interested in computing the parameters of this technological procedure, for the classic way of relieving, namely by heating up the external cylinder. After processing by cutting, radius R2 of the internal tube is greater than δ = 0.05 mm radius R2 of the external tube. After cooling, the two tubes have a common radius R2, which will have an average value between the values they had before the assembling process. This is why the external tube has to suffer a thermal expansion, the internal tube suffering a compression, so that the two displacements summed, measured perpendicular to the contact surface, have a value of δ = 0.05 mm. After the relieving operation, on the contact surface between the two tubes will be produces a contact pressure, p. In the paper we study the effect of the relieving pressure p, onto the stresses if there would be not relieving and the variation of stresses considering relieving of both the internal tube and the external tube. The highest values of the stresses are those on the internal face of the bearing. If calculations are in accordance with the third failure theory it results that the maximum

  17. 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.

  18. 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)

  19. 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.

  20. Flow in a torsionally oscillating filled cylinder

    NASA Technical Reports Server (NTRS)

    Schafer, C. F.

    1983-01-01

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

  1. Torsional Stability of Aluminum Alloy Seamless Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Paul, D A

    1939-01-01

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

  2. The Torsional Fundamental Band of Methylformate

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  3. 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.

  4. INTERIOR DETAIL, SECONDSTORY JOISTS, SUBFLOORING, AND FIREPLACE HEARTH RELIEVING ARCH. ...

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

    INTERIOR DETAIL, SECOND-STORY JOISTS, SUBFLOORING, AND FIREPLACE HEARTH RELIEVING ARCH. THESE FEATURES WERE MADE VISIBLE AFTER A 2002 FAILURE OF WHAT WAS LIKELY THE ORIGINAL EIGHTEENTH-CENTURY CEILING PLASTER IN THE SOUTHWEST CABINET - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA

  5. 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.

  6. 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.

  7. Strong field coherent control of molecular torsions--Analytical models.

    PubMed

    Ashwell, Benjamin A; Ramakrishna, S; Seideman, Tamar

    2015-08-14

    We introduce analytical models of torsional alignment by moderately intense laser pulses that are applicable to the limiting cases of the torsional barrier heights. Using these models, we explore in detail the role that the laser intensity and pulse duration play in coherent torsional dynamics, addressing both experimental and theoretical concerns. Our results suggest strategies for minimizing the risk of off-resonant ionization, noting the qualitative differences between the case of torsional alignment subject to a field-free torsional barrier and that of torsional alignment of a barrier-less system (equivalent to a 2D rigid rotor). We also investigate several interesting torsional phenomena, including the onset of impulsive alignment of torsions, field-driven oscillations in quantum number space, and the disappearance of an alignment upper bound observed for a rigid rotor in the impulsive torsional alignment limit. PMID:26277138

  8. 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.

  9. 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. PMID:24610598

  10. 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.

  11. Ritual relieved axial dystonia triggered by gaze-evoked amaurosis.

    PubMed

    Jacome, D E

    1997-11-01

    A woman with chronic posttraumatic axial lateropulsion cervical dystonia ("belly dancer's head") found relief of her spontaneous dystonic spasms by the sequential performance of an elaborate motor ritual. During an episode of left optic papillitis caused by central retinal vein occlusion, gaze-evoked amaurosis of the left eye developed, preceded by achromatopsia, during left lateral gaze. Gaze-evoked amaurosis triggered axial dystonia, which was followed by her unique, stereotyped, dystonia-relieving ritual that simulated a slow dance. Visual symptoms improved progressively in 1 year. Eventually, she was unable to trigger her dystonia by eye movements. Spontaneous dystonia remained otherwise unchanged from before the episode of papillitis and was still relieved by her unique ritual. PMID:9365340

  12. 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)

  13. Do OTC remedies relieve cough in acute URIs?

    PubMed

    Dealleaume, Lauren; Tweed, Beth; Neher, Jon O

    2009-10-01

    Dextromethorphan (DM) for adults and honey for children provide some relief. DM may modestly decrease cough in adults compared with placebo. The data supporting zinc for the common cold are mixed. Antihistamines, antihistamine-decongestant combinations, and guaifenesin do not provide greater relief than placebo in adults. In children, antihistamines, decongestants, DM, or combinations of them do not relieve cough better than placebo. Honey may modestly decrease frequency and severity of cough compared with DM or no treatment. PMID:19874728

  14. Aeroelastic considerations for torsionally soft rotors

    NASA Technical Reports Server (NTRS)

    Mantay, W. R.; Yeager, W. T., Jr.

    1985-01-01

    A research study was initiated to systematically determine the impact of selected blade tip geometric parameters on conformable rotor performance and loads characteristics. The model articulated rotors included baseline and torsionally soft blades with interchangeable tips. Seven blade tip designs were evaluated on the baseline rotor and six tip designs were tested on the torsionally soft blades. The designs incorporated a systemmatic variation in geometric parameters including sweep, taper, and anhedral. The rotors were evaluated in the NASA Langley Transonic Dynamics Tunnel at several advance ratios, lift and propulsive force values, and tip Mach numbers. A track sensitivity study was also conducted at several advance ratios for both rotors. Based on the test results, tip parameter variations generated significant rotor performance and loads differences for both baseline and torsionally soft blades.

  15. Surgical correction of torsion of the penis.

    PubMed

    Azmy, A; Eckstein, H B

    1981-08-01

    Torsion of the penis is a rare anomaly, believed to be due to abnormal skin attachment and not to any structural abnormality of the corpora. The rotation is usually to the left in a counter-clockwise fashion. The urethral meatus is placed in a oblique position and the median raphe makes a spiral curve from the base of the penis towards the meatus. Three boys with congenital torsion of the penis are reported. A corrective operative for this condition is described. Penile torsion was first described by Verneuil in 1857, but in the past no operative correction was recommended, since attempts to move the skin around were believed not to correct the spiral alignment of the corpora cavernosa. PMID:7260553

  16. 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.

  17. Helioseismic measurement of solar torsional oscillations.

    PubMed

    Vorontsov, S V; Christensen-Dalsgaard, J; Schou, J; Strakhov, V N; Thompson, M J

    2002-04-01

    Bands of slower and faster rotation, the so-called torsional oscillations, are observed at the Sun's surface to migrate in latitude over the 11-year solar cycle. Here, we report on the temporal variations of the Sun's internal rotation from solar p-mode frequencies obtained over nearly 6 years by the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO) satellite. The entire solar convective envelope appears to be involved in the torsional oscillations, with phase propagating poleward and equatorward from midlatitudes at all depths throughout the convective envelope. PMID:11935019

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

    PubMed Central

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

    2011-01-01

    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. PMID:22131584

  19. 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 ...

  20. Adnexal torsion: review of the literature.

    PubMed

    Sasaki, Kirsten J; Miller, Charles E

    2014-01-01

    Adnexal torsion is one of a few gynecologic surgical emergencies. Misdiagnosis or delay in treatment can have permanent sequelae including loss of an ovary with effect on future fertility, peritonitis, and even death. A PubMed search was performed between 1985 and 2012 for reviews, comparative studies, and case reports to provide a review of the epidemiology, risk factors, clinical presentation, common laboratory and imaging findings, and treatments of adnexal torsion. Common symptoms of torsion include pain, nausea, and vomiting, with associated abdominal or pelvic tenderness, and may differ in premenarchal and pregnant patients. Laboratory and imaging findings including ultrasound with Doppler analysis, computed tomography, and magnetic resonance imaging can assist in making the diagnosis but should not trump clinical judgment; normal Doppler flow can be observed in up to 60% of adnexal torsion cases. Treatment depends on the individual patient but commonly includes detorsion, even if the adnexae initially seem necrotic, with removal of any associated cysts or salpingo-oophorectomy, because recurrence rates are higher with detorsion alone or detorsion with only cyst aspiration. PMID:24126258

  1. Joining and forming using torsional ultrasonic principles.

    PubMed

    Frost, M

    2009-10-01

    Developments in torsional ultrasonic joining mean that it is now used in a diverse range of joining, forming, selective weakening and "break-off" applications in the medical device industry.The principles and benefits of the technique are described together with application examples. PMID:20302140

  2. 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

  3. Torsional Oscillations of the Earths's Core

    NASA Technical Reports Server (NTRS)

    Hide, Raymond; Boggs, Dale H.; Dickey, Jean O.

    1997-01-01

    Torsional oscillations of the Earth's liquid metallic outer core are investigated by diving the core into twenty imaginary e1qui-volume annuli coaxial with the axis of ratation of the Earth and determining temproal fluctuations in the axial component of angular memonetum of each annulus under the assumption of iso-rotation on cylindrical surfaces.

  4. Hepatic lobe torsion in a horse

    PubMed Central

    Bentz, Kristin J.; Burgess, Brandy A.; Lohmann, Katharina L.; Shahriar, Farshid

    2009-01-01

    A 4-year-old Belgian mare was presented with a 1-week history of fever, suspected of being caused by peritonitis. The mare died before the diagnostic procedures had been completed; postmortem examination revealed torsion of the left medial lobe of the liver, resulting in diffuse necrosis of liver tissue and severe peritoneal effusion. PMID:19436480

  5. 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...

  6. 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.

  7. 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.

  8. Evaluation of left ventricular torsion by cardiovascular magnetic resonance

    PubMed Central

    2012-01-01

    Recently there has been considerable interest in LV torsion and its relationship with symptomatic and pre-symptomatic disease processes. Torsion gives useful additional information about myocardial tissue performance in both systolic and diastolic function. CMR assessment of LV torsion is simply and efficiently performed. However, there is currently a wide variation in the reporting of torsional motion and the procedures used for its calculation. For example, torsion has been presented as twist (degrees), twist per length (degrees/mm), shear angle (degrees), and shear strain (dimensionless). This paper reviews current clinical applications and shows how torsion can give insights into LV mechanics and the influence of LV geometry and myocyte fiber architecture on cardiac function. Finally, it provides recommendations for CMR measurement protocols, attempts to stimulate standardization of torsion calculation, and suggests areas of useful future research. PMID:22827856

  9. Are children given insufficient pain-relieving medication postoperatively?

    PubMed

    Hamers, J P; Abu-Saad, H H; van den Hout, M A; Halfens, R J

    1998-01-01

    The literature often suggests and assumes that children are under-medicated postoperatively. A review of the literature leads to the conclusion that only a few studies answer the question of whether children's pain is relieved insufficiently. The lack of consensus on expected pain intensity after surgery and caution about prescribing analgesics could explain why analgesics are often prescribed on a pro re nata (prn) basis. Prescription on a prn basis, in fact, means that the nurse makes the decision whether or not an analgesic should be administered. Some studies suggest, however, that nurses under-medicate children and that postoperative pain is relieved insufficiently. In some situations, nurses under-estimate the child's pain, while in others, nurses' attitudes, beliefs and knowledge regarding pain relief strategies play an important role. On the basis of this review of the literature standard prescription of pain medication instead of prn is recommended. Furthermore, research on the incidence and prevalence of pain in children and on the effectiveness of analgesic administration postoperatively is warranted. PMID:9515606

  10. Sodium Hydrosulfide Relieves Neuropathic Pain in Chronic Constriction Injured Rats

    PubMed Central

    Lin, Jian-qing; Luo, Hui-qin; Lin, Cai-zhu; Chen, Jin-zhuan; Lin, Xian-zhong

    2014-01-01

    Aberrant neuronal activity in injured peripheral nerves is believed to be an important factor in the development of neuropathic pain (NPP). Channel protein pCREB of that activity has been shown to mitigate the onset of associated molecular events in the nervous system, and sodium hydrosulfide (NaHS) could inhibit the expression of pCREB. However, whether NaHS could relieve the pain, it needs further experimental research. Furthermore, the clinical potential that NaHS was used to relieve pain was limited so it would be required. To address these issues, the rats of sciatic nerve chronic constriction injury (CCI) were given intraperitoneal injection of NaHS containing hydrogen sulfide (H2S). The experimental results showed that NaHS inhibited the reduction of paw withdrawal thermal latency (PWTL), mechanical withdrawal threshold (MWT), and the level of pCREB in CCI rats in a dose-dependent manner and they were greatly decreased in NaHSM group (P < 0.05). NaHS alleviates chronic neuropathic pain by inhibiting expression of pCREB in the spinal cord of Sprague-Dawley rats. PMID:25506383

  11. 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

  12. Torsion and transverse bending of cantilever plates

    NASA Technical Reports Server (NTRS)

    Reissner, Eric; Stein, Manuel

    1951-01-01

    The problem of combined bending and torsion of cantilever plates of variable thickness, such as might be considered for solid thin high-speed airplane or missile wings, is considered in this paper. The deflections of the plate are assumed to vary linearly across the chord; minimization of the potential energy by means of the calculus of variations then leads to two ordinary linear differential equations for the bending deflections and the twist of the plate. Because the cantilever is analyzed as a plate rather than as a beam, the effect of constraint against axial warping in torsion is inherently included. The application of this method to specific problems involving static deflection, vibration, and buckling of cantilever plates is presented. In the static-deflection problems, taper and sweep are considered.

  13. 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.

  14. 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

  15. 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. PMID:26799324

  16. Implementing torsional-mode Doppler ladar.

    PubMed

    Fluckiger, David U

    2002-08-20

    Laguerre-Gaussian laser modes carry orbital angular momentum as a consequence of their helical-phase front screw dislocation. This torsional beam structure interacts with rotating targets, changing the orbital angular momentum (azimuthal Doppler) of the scattered beam because angular momentum is a conserved quantity. I show how to measure this change independently from the usual longitudinal momentum (normal Doppler shift) and derive the apropos coherent mixing efficiencies for monostatic, truncated Laguerre and Gaussian-mode ladar antenna patterns. PMID:12206220

  17. 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.

  18. Analytic Model for the Rototranslational Torsion Pendulum

    NASA Astrophysics Data System (ADS)

    De Marchi, F.; Bassan, M.; Pucacco, G.; Marconi, L.; Stanga, R.; Visco, M.

    2013-01-01

    We develop an analytic model to describe the motion of the RotoTranslational Torsion Pendulum PETER in a wide range of frequencies (from 1mHz up to 10-15Hz). We also try to explain some unexpected features we found in the data with only 1 soft degree of freedom and we estimate values for the misalignment angles and other parameters of the model.

  19. Dark spinors with torsion in cosmology

    SciTech Connect

    Boehmer, Christian G.; Burnett, James

    2008-11-15

    We solve one of the open problems in Einstein-Cartan theory, namely, we find a natural matter source whose spin angular momentum tensor is compatible with the cosmological principle. We analyze the resulting evolution equations and find that an epoch of accelerated expansion is an attractor. The torsion field quickly decays in that period. Our results are interpreted in the context of the standard model of cosmology.

  20. 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.

  1. Liver lobe torsion in three adult rabbits.

    PubMed

    Wenger, S; Barrett, E L; Pearson, G R; Sayers, I; Blakey, C; Redrobe, S

    2009-06-01

    This paper describes three cases of liver lobe torsion in rabbits presenting with anorexia, lethargy, jaundice and abdominal pain. This condition was associated with anaemia and elevation of alanine aminotransferase, aspartate aminotransferase and gamma-glutamyl transferase. Abnormal radiological findings included hepatomegaly, gas-filled intestinal loops consistent with gastrointestinal ileus and ascites. Ultrasonographic findings included heterogeneous liver parenchyma, free abdominal fluid and reduced bowel motility. Diagnosis was confirmed by histopathological examination of the liver in all three cases. PMID:19527423

  2. Ubiquitous Torsional Motions in Type II Spicules

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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-1, (2) swaying motions of order 15-20 km s-1, and (3) torsional motions of order 25-30 km s-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 Alfvénic waves propagating outward at several hundred km s-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 Alfvénic 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.

  3. Fundamentals of IC engine torsional vibration

    SciTech Connect

    Doughty, S.

    1988-01-01

    Fluctuations in IC engine cylinder pressure are an obvious source of torsional vibration excitation, although the details of the coupling from cylinder pressure to torque on the crankshaft are complicated. A second, less obvious source of torsional excitation is the effect of variable inertia associated with the engine slider-crank mechanism. This is a tutorial paper, intended to show the relation between, on the one hand, the actual engine slider-crank mechanism subject to combustion gas pressure and, on the other hand, the models commonly used for torsional vibration analysis that involve constant inertias subject to torques expressed by Fourier series. As such, it uses some new approaches to reach previously known results with a greater degree of physical insight. The presentation is in terms of a single cylinder, two stroke engine with load, and makes clear the roles of piston mass, connecting rod mass and moment of inertia, and crank inertia as they affect both the effective inertia and the effective torque. The determination of natural frequencies and the forced vibration response calculation are briefly described to complete the analysis. The development of a Fourier series representation for the effective torque, including both the cylinder pressure and inertia variation is also discussed. The various components for the response are identified, in an effort to clarify the meaning of terms such as ''zero frequency mode,'' ''rigid body mode,'' and ''twisting mode.''

  4. 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. PMID:24826979

  5. Torsional Oscillator Studies on Solid Helium

    NASA Astrophysics Data System (ADS)

    Kim, Duk Y.; Chan, Moses H. W.

    2014-03-01

    In 2004, the series of torsional oscillator (TO) experiments by Kim and Chan initiated considerable research activities on the supersolidity of helium. However, recent experiments in rigid torsional oscillators which reduce the effect of stiffening of bulk solid helium at low temepratures showed very small or negligible changes in the resonant period. A new TO experiment of solid helium confined in porous Vycor glass with no bulk solid helium in the sample cell show no evidence of supersolidity. Moreover, we have repeated an earlier experiment on hcp 3He solid, which shows similar low temperature stiffening like hcp 4He. We found that the small drop of the resonant period measured in the hcp 3He samples is comparable to that measured in the hcp 4He samples. These results confirm that the resonant period drops in torsional oscillators are consequence of the shear modulus stiffening effect in solid helium. Remaining issues and open questions on the supersolidity will be discussed. Support for this experiment was provided by NSF Grants No. DMR 1103159.

  6. Isolated fallopian tube torsion in adolescents.

    PubMed

    Rajaram, S; Bhaskaran, S; Mehta, S

    2013-01-01

    Background. Fallopian tube torsion is a rare cause of acute abdomen, occurring commonly in females of reproductive age. It lacks pathognomonic symptoms, signs, or imaging features, thus causing delay in surgical intervention. Case. We report two cases of isolated fallopian tube torsion in adolescent girls. In the first case a 19-year-old patient presented with acute pain in the left iliac region associated with episodes of vomiting for one day and mild tenderness on examination. Laparoscopy revealed left sided twisted fallopian tube associated with hemorrhagic cyst of ovary. The tube was untwisted and salvaged. In another case an 18-year-old virgin girl presented with similar complaints since one week, associated with mild tenderness in the lower abdomen and tender cystic mass on per rectal examination. On laparoscopy right twisted fallopian tube associated with a paratubal cyst was found. Salpingectomy was done as the tube was gangrenous. Conclusion. Fallopian tube torsion, though rare, should be considered in women of reproductive age with unilateral pelvic pain. Early diagnostic laparoscopy is important for an accurate diagnosis and could salvage the tube. PMID:24251052

  7. Torsional oscillations in the solar convection zone

    NASA Astrophysics Data System (ADS)

    Covas, E.; Tavakol, R.; Moss, D.; Tworkowski, A.

    2000-08-01

    Recent analysis of the helioseismic observations indicate that the previously observed surface torsional oscillations extend significantly downwards into the solar convection zone. In an attempt to understand these oscillations, we study the nonlinear coupling between the magnetic field and the solar differential rotation in the context of a mean field dynamo model, in which the nonlinearity is due to the action of the azimuthal component of the Lorentz force of the dynamo generated magnetic field on the solar angular velocity. The underlying zero order angular velocity is chosen to be consistent with the most recent helioseismic data. The model produces butterfly diagrams which are in qualitative agreement with the observations. It displays torsional oscillations that penetrate into the convection zone, and which with time migrate towards the equator. The period of these oscillations is found to be half that of the period of the global magnetic fields. This is compatible with the observed period of the surface torsional oscillations. Inside the convection zone, this is a testable prediction that is not ruled out by the observations so far available.

  8. Torsional optokinetic nystagmus: normal response characteristics

    PubMed Central

    Farooq, S J; Proudlock, F A; Gottlob, I

    2004-01-01

    Background/aims: Few studies have investigated normal response characteristics of torsional optokinetic nystagmus (tOKN). The authors have investigated the effect of stimulus velocity and central/peripheral stimulation on tOKN. Methods: Torsional OKN was elicited using a sinusoidal grating rotating at velocities of 3°/s to 1000°/s in clockwise and anticlockwise directions. To investigate the effect of central stimulation, stimulus size was varied from 2.86° to 50.8°. An artificial scotoma placed over a 50.8° stimulus was varied from 2.86° to 43.2° to investigate peripheral stimulation. Eight subjects participated in each experiment and torsional eye movements were recorded using video-oculography. The mean slow phase velocity (MSPV) and gain were calculated. Results: The maximum gain occurred in response to 8°/s stimulation. The MSPV increased up to a stimulus velocity of 200°/s achieving a maximum of 3°/s in both directions. MSPV was linearly correlated with the log of stimulus velocity. The smallest field size, rotating at 40°/s, evoked 10% of the gain elicited by the largest display. When the most peripheral stimulus was used, the gain was maintained at 50% of the gain evoked when the full display was used. Conclusions: A wide range of stimulus velocities can elicit tOKN and peripheral field stimulation contributes significantly to its response. PMID:15148215

  9. Does nebulized fentanyl relieve dyspnea during exercise in healthy man?

    PubMed Central

    Kotrach, Houssam G.; Bourbeau, Jean

    2015-01-01

    Few therapies exist for the relief of dyspnea in restrictive lung disorders. Accumulating evidence suggests that nebulized opioids selective for the mu-receptor subtype may relieve dyspnea by modulating intrapulmonary opioid receptor activity. Our respective primary and secondary objectives were to test the hypothesis that nebulized fentanyl (a mu-opioid receptor agonist) relieves dyspnea during exercise in the presence of abnormal restrictive ventilatory constraints and to identify the physiological mechanisms of this improvement. In a randomized, double-blind, placebo-controlled crossover study, we examined the effect of 250 μg nebulized fentanyl, chest wall strapping (CWS), and their interaction on detailed physiological and perceptual responses to constant work rate cycle exercise (85% of maximum incremental work rate) in 14 healthy, fit young men. By design, CWS decreased vital capacity by ∼20% and mimicked the negative consequences of a mild restrictive lung disorder on exercise endurance time and on dyspnea, breathing pattern, dynamic operating lung volumes, and diaphragmatic electromyographic and respiratory muscle function during exercise. Compared with placebo under both unrestricted control and CWS conditions, nebulized fentanyl had no effect on exercise endurance time, integrated physiological response to exercise, sensory intensity, unpleasantness ratings of exertional dyspnea. Our results do not support a role for intrapulmonary opioids in the neuromodulation of exertional dyspnea in health nor do they provide a physiological rationale for the use of nebulized fentanyl in the management of dyspnea due to mild restrictive lung disorders, specifically those arising from abnormalities of the chest wall and not affiliated with airway inflammation. PMID:26031762

  10. Does nebulized fentanyl relieve dyspnea during exercise in healthy man?

    PubMed

    Kotrach, Houssam G; Bourbeau, Jean; Jensen, Dennis

    2015-06-01

    Few therapies exist for the relief of dyspnea in restrictive lung disorders. Accumulating evidence suggests that nebulized opioids selective for the mu-receptor subtype may relieve dyspnea by modulating intrapulmonary opioid receptor activity. Our respective primary and secondary objectives were to test the hypothesis that nebulized fentanyl (a mu-opioid receptor agonist) relieves dyspnea during exercise in the presence of abnormal restrictive ventilatory constraints and to identify the physiological mechanisms of this improvement. In a randomized, double-blind, placebo-controlled crossover study, we examined the effect of 250 μg nebulized fentanyl, chest wall strapping (CWS), and their interaction on detailed physiological and perceptual responses to constant work rate cycle exercise (85% of maximum incremental work rate) in 14 healthy, fit young men. By design, CWS decreased vital capacity by ∼20% and mimicked the negative consequences of a mild restrictive lung disorder on exercise endurance time and on dyspnea, breathing pattern, dynamic operating lung volumes, and diaphragmatic electromyographic and respiratory muscle function during exercise. Compared with placebo under both unrestricted control and CWS conditions, nebulized fentanyl had no effect on exercise endurance time, integrated physiological response to exercise, sensory intensity, unpleasantness ratings of exertional dyspnea. Our results do not support a role for intrapulmonary opioids in the neuromodulation of exertional dyspnea in health nor do they provide a physiological rationale for the use of nebulized fentanyl in the management of dyspnea due to mild restrictive lung disorders, specifically those arising from abnormalities of the chest wall and not affiliated with airway inflammation. PMID:26031762

  11. Torsional and biaxial (tension-torsion) fatigue damage mechanisms in Waspaloy at room temperature

    NASA Technical Reports Server (NTRS)

    Jayaraman, N.; Ditmars, M. M.

    1989-01-01

    Strain controlled torsional and biaxial (tension-torsion) low cycle fatigue behavior of Waspaloy was studied at room temperature as a function of heat treatment. Biaxial tests were conducted under proportional and nonproportional cyclic conditions. The deformation behavior under these different cyclic conditions was evaluated by slip trace analysis. For this, a Schmidt-type factor was defined for multiaxial loading conditions, and it was shown that when the slip deformation is predominant, nonproportional cycles are more damaging than proportional or pure axial or torsional cycles. This was attributed to the fact that under nonproportional cyclic conditions, deformation was through multiple slip, as opposed to single slip for other loading conditions, which gave rise to increased hardening. The total life for a given test condition was found to be independent of heat treatment. This was interpreted as being due to the differences in the cycles to initiation and propagation of cracks.

  12. 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

  13. 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

  14. Torsion discovery potential and its discrimination at CERN LHC

    SciTech Connect

    Almeida, F. M. L. Jr. de; Nepomuceno, A. A.; Vale, M. A. B. do

    2009-01-01

    Torsion models constitute a well-known class of extended quantum gravity models. In this paper we study some phenomenological consequences of a torsion field interacting with fermions at LHC. A torsion field could appear as a new heavy state characterized by its mass and couplings to fermions. These new states will form a resonance decaying into difermions, as occurs in many extensions of the standard model, such as models predicting the existence of additional neutral gauge bosons, usually named Z{sup '}. Using the dielectron channel we evaluate the integrated luminosity needed for a 5{sigma} discovery as a function of the torsion mass, for different coupling values. We also calculate the luminosity needed to discriminate, with 95% C.L., the two possible different torsion natures. Finally, we show that the observed signal coming from the torsion field could be distinguished from a signal coming from a new neutral gauge boson, provided there is enough luminosity.

  15. Can Gravity Probe B usefully constrain torsion gravity theories?

    SciTech Connect

    Flanagan, Eanna E.; Rosenthal, Eran

    2007-06-15

    In most theories of gravity involving torsion, the source for torsion is the intrinsic spin of matter. Since the spins of fermions are normally randomly oriented in macroscopic bodies, the amount of torsion generated by macroscopic bodies is normally negligible. However, in a recent paper, Mao et al. (arXiv:gr-qc/0608121) point out that there is a class of theories, including the Hayashi-Shirafuji (1979) theory, in which the angular momentum of macroscopic spinning bodies generates a significant amount of torsion. They further argue that, by the principle of action equals reaction, one would expect the angular momentum of test bodies to couple to a background torsion field, and therefore the precession of the Gravity Probe B gyroscopes should be affected in these theories by the torsion generated by the Earth. We show that in fact the principle of action equals reaction does not apply to these theories, essentially because the torsion is not an independent dynamical degree of freedom. We examine in detail a generalization of the Hayashi-Shirafuji theory suggested by Mao et al. called Einstein-Hayashi-Shirafuji theory. There are a variety of different versions of this theory, depending on the precise form of the coupling to matter chosen for the torsion. We show that, for any coupling to matter that is compatible with the spin transport equation postulated by Mao et al., the theory has either ghosts or an ill-posed initial-value formulation. These theoretical problems can be avoided by specializing the parameters of the theory and in addition choosing the standard minimal coupling to matter of the torsion tensor. This yields a consistent theory, but one in which the action equals reaction principle is violated, and in which the angular momentum of the gyroscopes does not couple to the Earth's torsion field. Thus, the Einstein-Hayashi-Shirafuji theory does not predict a detectable torsion signal for Gravity Probe B. There may be other torsion theories which do.

  16. Torsion-gravity for Dirac fields and their effective phenomenology

    NASA Astrophysics Data System (ADS)

    Fabbri, Luca

    2014-08-01

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

  17. Ovarian torsion: opportunities to improve clinical management.

    PubMed

    Bharathan, R; Ramsawak, L; Kelly, A

    2012-10-01

    Ovarian torsion is an uncommon condition which may affect women of any age. In a significant number of women, it may be associated with a concomitant pathology such as a cyst. Presently, there is no single diagnostic tool with significant predictive value. Multimodal diagnostic tools hold promise of early accurate diagnosis; prospective studies are required to assess the validity of such tools. This would enable wider application of ovarian function preserving procedures. Further, an assessment of the psychological impact of oophorectomy should be studied in order to facilitate the optimal tailored care. PMID:22943718

  18. Aspects of Interacting Electromagnetic and Torsion Fields

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio; Helaÿel-Neto, José A.

    2011-01-01

    The interaction energy is studied for the coupling of axial torsion fields with photons in the presence of an external electromagnetic field. To this end, we compute the static quantum potential. Our discussion is carried out using the gauge-invariant but path-dependent variables formalism, which is alternative to the Wilson loop approach. Our results show that the static potential is a Yukawa correction to the usual static Coulomb potential. Interestingly, when this calculation is done by considering a mass term for the gauge field, the Coulombic piece disappears leading to a screening phase.

  19. 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

  20. 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. PMID:26945235

  1. 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

  2. Emergency pulpotomy in relieving acute dental pain among Tanzanian patients

    PubMed Central

    Nyerere, Joachim W; Matee, Mecky I; Simon, Elison NM

    2006-01-01

    Background In Tanzania, oral health services are mostly in the form of dental extractions aimed at alleviating acute dental pain. Conservative methods of alleviating acute dental pain are virtually non-existent. Therefore, it was the aim of this study to determine treatment success of emergency pulpotomy in relieving acute dental pain. Methods Setting: School of Dentistry, Muhimbili National Hospital, Dar es Salaam, Tanzania. Study design: Longitudinal study. Participants: 180 patients who presented with dental pain due to acute irreversible pulpitis during the study period between July and August 2001. Treatment and evaluation: Patients were treated by emergency pulpotomy on permanent posterior teeth and were evaluated for pain after one, three and six week's post-treatment. Pain, if present, was categorised as either mild or acute. Results Of the patients with treated premolars, 25 (13.9%) patients did not experience pain at all while 19 (10.6%) experienced mild pain. None of the patients with treated premolars experienced acute pain. Among 136 patients with treated molars 56 (31%) did not experience any pain, 76 (42.2%) experienced mild pain and the other 4 (2.2%) suffered acute pain. Conclusion The short term treatment success of emergency pulpotomy was high being 100% for premolars and 97.1% for molars, suggesting that it can be recommended as a measure to alleviate acute dental pain while other conservative treatment options are being considered. PMID:16426455

  3. 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. PMID:27023425

  4. 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.

  5. Analysis of interlaminar stresses in the torsion of symmetric laminates

    NASA Astrophysics Data System (ADS)

    Whitney, James M.

    1994-03-01

    In the present paper the effect of transverse (interlaminar) normal strain on the torsional response of symmetrically laminated, anisotropic plates is investigated. The analysis is based on a modified form of the global laminate model developed by Pagano and Soni. In-plane stresses are modified in the boundary zone to satisfy free-edge boundary conditions. For the general case of angle-ply layers, a laminated composite behaves in a manner similar to an anisotropic plate. The existence of the bending-twisting coupling phenomenon found in the case of anisotropic plates leads to two classic problems in conjunction with torsional loading. In the first case, referred to as 'pure torsion,' the torsional axis of the plates does not bend. Thus, an axial bending moment is required in addition to the torsional load to suppress plate bending. In the second case, referred to as 'free torsion,' the only loading is torque in which anisotropy induces bending of the torsional axis. For the purposes of this paper it is sufficient to consider the case of pure torsion only.

  6. Two Cases of Omental Torsion Mimicking Acute Appendicitis

    PubMed Central

    Liaqat, Naeem; Dar, Sajid Hameed; Sandhu, Asif Iqbal; Nayyer, Sajid

    2014-01-01

    Acute appendicitis is often simulated by other entities like mesenteric adenitis, worm infestation, Meckel’s diverticulitis, urinary tract infection and rarely omental torsion. We report two cases, a 6 year old boy and an 11 year old girl, who presented with symptoms and signs of acute appendicitis but upon exploration turned out to be omental torsion. PMID:24834389

  7. Diagnostic Efficacy of Sonography for Diagnosis of Ovarian Torsion

    PubMed Central

    Rostamzadeh, Ayoob; Mirfendereski, Sam; Rezaie, Mohammad Jafar; Rezaei, Shohreh

    2014-01-01

    Objectives: Misdiagnosing ovarian torsion is now suggested as an important issue in clinical setting. The aim of this study was to determine the diagnostic accuracy of sonography for ovarian torsion. Methods : In this study 323 women with acute pelvic pain with highly suspected ovarian torsion signs and symptoms attending Imam Reza Medical Center in Kermanshah between 2011 through 2012 were included and underwent a transabdominal sonography (2-5 MHz probes). Then findings of sonography were compared with laparatomy. Results : The ultrasound correctly diagnosed 72.1% of ovarian torsion and missed 27.9% of them (false negatives). However, one free subject (0.4%) was misclassified as ovarian torsion (false positive). There was a strong correlation between sonography and laparatomy with a kappa value of 84.0%. The sensitivity and specificity of sonography were 72.1% and 99.6%, respectively. Sonography had a positive predictive value of 96.9%, a negative predictive value of 95.9%, and a total accuracy of 96.0% for detection of ovarian torsion. Conclusion: Sonography appears to be an excellent method to evaluate patients with suspected ovarian torsion. Abnormal blood flow detected by sonography is highly predictive of ovarian torsion and is therefore useful in the diagnosis of this phenomenon. PMID:24772154

  8. Torsional Strengthening of RC Beams Using GFRP Composites

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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.

  9. 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.

  10. 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.

  11. 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.

  12. Torsion and transverse sensing of conical shells

    NASA Astrophysics Data System (ADS)

    Li, H.; Chen, Z. B.; Tzou, H. S.

    2010-10-01

    Conical shells are widely used as payload/rocket adapters in rocket fairing systems. Generally, the conical shells are clamped at the major end and free at the minor end, where the payload is mounted. This study focuses on the dynamic sensing of conical shells with fix-free boundary conditions (BCs) by using distributed piezoelectric helical sensors. Two types of motion are studied, i.e., the transverse modes and the torsion modes. The shear-type sensors for shells sensing are presented first. Formulations of sensing signals of a general shell of revolution are presented, and then simplified to conical shells. For sensing of transverse vibrations, thin piezoelectric sensors are laminated on the top surface. Two types of sensor distribution are considered: a fully distributed and a helical or diagonal laminated. The total signal consists of four components resulting from the four strain components, and each of them is evaluated in detail. For sensing of torsion vibrations, a meridional polarized shear-type sensor with side electrodes is layered on the top surface of the shell structure. Sensing signals of natural shell modes are also evaluated. Analyses show that, in low order modes, the sensing signals induced by the circumferential membrane strains are the primary components of the total signal generations. The numerical results indicate the optimal location of the sensors. The proposed method is capable of determining the modal participation factors, while the testing signal is available; it is also capable of determining the mode shapes by using several distributed sensor segments.

  13. Fertility after oophorectomy due to torsion

    PubMed Central

    Al-Turki, Haifa A.

    2015-01-01

    Objectives: To investigate the prevalence of infertility in patients who underwent salpingo-oophorectomy due to adnexal torsion (AT). Methods: All adult women admitted to the Teaching Institution of the University of Dammam, Dammam, Saudi Arabia who underwent surgery due to AT between January 2001 and 2010 were included. Complete data was collected from the time of admission to the follow up. The data was entered into the database and analyzed. Results: The data of 26 patients was available for analysis. The mean age (±standard deviation) at presentation was 22.19±4.4 years, and average age at follow up was 34.81±5.75 years. The average delay in presentation was 37.76±47 hours, and the surgery was performed at 45.07±48.57 hours. The right side was involved in 13 (53.8%) of the cases. Fourteen (53.9%) women presented with infertility. Eleven (78.57%) were treated for infertility, and 5 (45.5%) conceived. Patients who were younger at the time of torsion fared better with regard to pregnancy (p<0.03, 95% confidence interval:-6.85; <0.58). Conclusion: Patients who undergo salpingo-oophorectomy for AT have an increased risk of infertility and should be warned of this impending complication. PMID:25737184

  14. Infrared modified gravity with dynamical torsion

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

  15. 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.

  16. Biothermal sensing of a torsional artificial muscle.

    PubMed

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

    2016-02-14

    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. PMID:26806884

  17. 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.

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

    PubMed

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

    2013-03-14

    Crystal structure databases offer ample opportunities to derive small molecule conformation preferences, but the derived knowledge is not systematically applied in drug discovery research. We address this gap by a comprehensive and extendable expert system enabling quick assessment of the probability of a given conformation to occur. It is based on a hierarchical system of torsion patterns that cover a large part of druglike chemical space. Each torsion pattern has associated frequency histograms generated from CSD and PDB data and, derived from the histograms, traffic-light rules for frequently observed, rare, and highly unlikely torsion ranges. Structures imported into the corresponding software are annotated according to these rules. We present the concept behind the tree of torsion patterns, the design of an intuitive user interface for the management and usage of the torsion library, and we illustrate how the system helps analyze and understand conformation properties of substructures widely used in medicinal chemistry. PMID:23379567

  19. Tailoring patterns of graphene wrinkles by circular torsion

    NASA Astrophysics Data System (ADS)

    Becton, Matthew; Wang, Xianqiao

    2016-02-01

    Wrinkled graphene has been emerging as a hot topic of interest due to its easily induced physical changes accompanied by changes in its material behavior. However, the wrinkling pattern of graphene and its relevant properties remain poorly understood. Here we employ molecular dynamics simulations to model the behavior of graphene under periodic, torsional wrinkling and elucidate the effect of torsion pattern, torsion velocity, and hole size on the wrinkling characteristics of a large graphene sheet. Simulation results show that gross control over the wrinkling pattern is feasible via manipulation of torsion direction and relative hole size, with fine-tuning of the wrinkle formation possible by control of the relative torsion speed of each hole.

  20. Torsional ARC Effectively Expands the Visual Field in Hemianopia

    PubMed Central

    Satgunam, PremNandhini; Peli, Eli

    2012-01-01

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

  1. [The effect of DNA supercoiling DNA on nucleosome structure].

    PubMed

    Sivolob, A V; Khrapunov, S N

    1991-01-01

    The circular DNA which contains nucleosomes and additional supercoils has been considered theoretically. The different possible effect of increased negative supercoiling on the nucleosome structure have been studied. According to the model proposed all supercoils in the nucleosome-containing circular DNA are realized as torsional deformations of the double helix. The free energy of both supercoiling (torsional deformations) and nucleosome stabilization have been taken into consideration to obtain the equation for free energy of nucleosome-containing circular DNA. The analysis of this equation and the experimental data by Garner et al. (II Psoc. Natl. Acad. Sci. USA. 1987. P. 2620-2623) about the maximum amount of supercoiling obtained by DNA-topoisomerase II treatment of nucleosome-containing pBR322 plasmid has been performed. It has been shown that two possibilities are consistent with both the equation and experimental data. These are: (1) the increased supercoiling induces the torsional strains not only in linker regions but also in nucleosome DNA and thus supercoiling causes an instability on nucleosome structure; (2) increased supercoiling induces a structural change of nucleosome which is accompanied by nucleosome DNA unwinding and its transition into form with approximately 11 base pairs per turn of double helix. It has been evaluated that in the first case the average torsional rigidity of nucleosome DNA should be approximately 2.5 times as much and in the second case--much more than the rigidity of naked DNA. Both types of nucleosome structural changes may cause its transition to a potentially active state for transcription. It is suggested that increased supercoiling can be a switch mechanism of chromatin activation. PMID:1654518

  2. The management of moderate and severe congenital penile torsion associated with hypospadias: Urethral mobilisation is not a panacea against torsion

    PubMed Central

    Elbakry, Adel; Zakaria, Ahmed; Matar, Adel; El Nashar, Ahmed

    2013-01-01

    Objectives To evaluate the effectiveness of urethral mobilisation for correcting moderate and severe penile torsion associated with distal hypospadias. Patients and methods Nineteen patients with distal hypospadias and congenital moderate and severe penile torsion were treated surgically. The hypospadias was at the distal shaft, coronal and glanular in seven, eight and four patients, respectively, and six had mild chordee. The mean (SD, range) angle of torsion was 94.7 (19.9, 75–160)°. The urethra was mobilised down to the perineum. If the urethral mobilisation was insufficient the right border of the tunica albuginea was anchored to the pubic periosteum. The hypospadias was repaired using the urethral mobilisation and advancement technique, with a triangular plate flap for meatoplasty. The patients were followed up for 12–18 months. Results All patients had a successful functional and cosmetic outcome, with no residual torsion. Two patients had a small subcutaneous haematoma that resolved after conservative treatment. Massive oedema occurred in three patients and was treated conservatively. Urethral mobilisation did not correct the penile torsion completely. Although the mean (SD, range) angle of torsion was reduced to 86.1 (14.3, 65–130)°, statistically significantly different (P = 0.001), it was not clinically important. The presence of chordee had no significant correlation with the reduction of penile torsion. Conclusion Urethral mobilisation cannot completely correct moderate and severe penile torsion but it might only partly decrease the angle of torsion. Periosteal anchoring of the tunica albuginea might be the most reliable manoeuvre for the complete correction of penile torsion. PMID:26579237

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

    NASA Astrophysics Data System (ADS)

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

    1995-04-01

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

  4. Combined bending-torsion fatigue reliability. III

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  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. Torsion Balance Test of Einstein's Equivalence Principle

    NASA Astrophysics Data System (ADS)

    Abercrombie, Michael; Archibald, Adam; Nussinov, Tsitsi; Wagoner, Kasey; Cowsik, Ramanath

    2016-03-01

    We have developed a torsion balance experiment to test the equivalence principle (EP) which follows the solar attractor approach pioneered by Dicke in the early 1960s. By monitoring the response of a balance arranged as a composition dipole with an azimuthally symmetric mass distribution to the gravitational field produced by the Sun, we search for a diurnal modulation of the balance which would indicate a violation of the EP. Since reporting on the status of this experiment last year, the instrument has begun collecting data at a remote underground site. This talk will cover the design and fundamental sensitivity of the balance, and present the results of preliminary analysis of over 1200 hours of data.

  7. 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)

  8. 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.

  9. 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.

  10. 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. PMID:24882020

  11. 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.

  12. 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.

  13. Pearls and pitfalls in diagnosis of ovarian torsion.

    PubMed

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

    2008-01-01

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

  14. Significance of torsion modes in bowed-string dynamics

    NASA Astrophysics Data System (ADS)

    Inacio, Octavio; Antunes, Jose; Henrique, Luis

    2002-11-01

    Several aspects of bowed-string dynamics are still inadequately clarified. The importance of torsion modes on the motion regimes is one such issue. Experiments involving torsion are difficult and most of the results available pertain to numerical simulations. The authors' approach differs from previous efforts in two main aspects: (1) the development of a computational method distinct from the wave-propagation approach pioneered by McIntyre, Schumacher, and Woodhouse and (2) an extensive and systematic analysis of the coupling between torsion and transverse motions is performed. The numerical simulations are based on a modal representation of the unconstrained string and a computational approach for friction that enables accurate representations of the stick-slip forces and of the string dynamics, in both time and space. Many relevant aspects of the bowed-string can be readily implemented, including string inharmonic behavior, finite bow-width, and torsion effects. Concerning the later aspect, a realistic range of the torsional to transverse wave-speed ratio is investigated, for several values of the bow velocity and normal force. Results suggest that torsion modes can effect both transient durations and steady state regimes, in particular when the above-mentioned ratio is <4. Gut strings should then be particularly prone to torsion effects.

  15. 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.

  16. 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.

  17. Four-fermion interaction from torsion as dark energy

    NASA Astrophysics Data System (ADS)

    Popławski, Nikodem J.

    2012-02-01

    The observed small, positive cosmological constant may originate from a four-fermion interaction generated by the spin-torsion coupling in the Einstein-Cartan-Sciama-Kibble gravity if the fermions are condensing. In particular, such a condensation occurs for quark fields during the quark-gluon/hadron phase transition in the early Universe. We study how the torsion-induced four-fermion interaction is affected by adding two terms to the Dirac Lagrangian density: the parity-violating pseudoscalar density dual to the curvature tensor and a spinor-bilinear scalar density which measures the nonminimal coupling of fermions to torsion.

  18. 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.

  19. Coupling and degenerating modes in longitudinal-torsional step horns.

    PubMed

    Harkness, Patrick; Lucas, Margaret; Cardoni, Andrea

    2012-12-01

    Longitudinal-torsional vibration is used and proposed for a variety of ultrasonic applications including motors, welding, and rock-cutting. To obtain this behavior in an ultrasonic step horn one can either, (i) couple the longitudinal and torsional modes of the horn by incorporating a ring of diagonal slits in the thick base section or, (ii) place helical flutes in the thin stem section to degenerate the longitudinal mode into a modified behavior with a longitudinal-torsional motion. This paper compares the efficacy of these two design approaches using both numerical and experimental techniques. PMID:22770885

  20. 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.

  1. The Torsion of Box Beams with One Side Lacking

    NASA Technical Reports Server (NTRS)

    Cambilargiu, E

    1940-01-01

    The torsion of box beams of rectangular section, the edges of which are strengthened by flanges, and of which one side is lacking, is analyzed by the energy method. The torsional stresses are generally taken up by the bending of the two parallel walls, the rigidity of which is augmented by the third wall. The result was checked experimentally on duralumin and plywood boxes. The torsion recorded was 10 to 30 percent less than that given by the calculation, owing to self-stiffening.

  2. A Novel Endoscopic Method to Relieve Food Impaction Using an Inflatable Balloon.

    PubMed

    Anand, Rohit; Garg, Shashank; Dubin, Ethan; Dutta, Sudhir

    2015-01-01

    Food impaction in the esophagus is a relatively common medical emergency. Most of these food impactions are relieved spontaneously. But for complete esophageal food impactions or impactions not relieved spontaneously, traditional endoscopic methods like using a Roth net, polypectomy snare, or rat or alligator tooth forceps are used to gently manipulate the food material into the stomach. However, these methods may not work in certain circumstances. We present a case of proximal esophageal food impaction that was relieved using an inflatable balloon after the conventional methods proved unsuccessful. PMID:26266059

  3. 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.

  4. 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.

  5. 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. PMID:24860026

  6. Randall-Sundrum scenario with bulk dilaton and torsion

    SciTech Connect

    Mukhopadhyaya, Biswarup; Sen, Somasri; SenGupta, Soumitra

    2009-06-15

    We consider a string-inspired torsion-dilaton-gravity action in a Randall-Sundrum braneworld scenario and show that, in an effective four-dimensional theory on the visible brane, the rank-2 antisymmetric Kalb-Ramond field (source of torsion) is exponentially suppressed. The result is similar to our earlier result in [B. Mukhopadhyaya, S. Sen, and S. SenGupta, Phys. Rev. Lett. 89, 121101 (2002); Phys. Rev. Lett. 89, 259902(E) (2002)], where no dilaton was present in the bulk. This offers an explanation of the apparent invisibility of torsion in our space-time. However, in this case the trilinear couplings {approx}TeV{sup -1} between the dilaton and torsion may lead to new signals in TeV-scale experiments, bearing the stamp of extra warped dimensions.

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

    PubMed

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

    2016-01-01

    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. PMID:27307430

  8. 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.

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

    PubMed Central

    Kahramanoglu, Ilker; Eroglu, Vasfiye; Turan, Hasan; Kaval, Gizem; Sal, Veysel; Tokgozoglu, Nedim

    2016-01-01

    Background Adnexal torsion can be a life-threatning condition in pregnancy, while the risk of late diagnosis is increased, in second and third trimester in particular. Laparoscopy is an effective approach in diagnosis and treatment of adnexal torsion. However, entry to abdomen may be challenging in more advanced pregnancies. Case report Herein, we report a case of adnexal torsion during 20th week of twin pregnancy, which was detorsioned laparoscopically. The woman delivered healthy infants at her 36th week of pregnancy. Discussion Adnexal torsion as a cause of acute abdomen may be kept in mind in pregnants, even if there is no predisposing factor. Laparoscopy may be performed safely in 2nd trimester for acute abdomen. PMID:27129134

  10. Structural diversity of supercoiled DNA

    NASA Astrophysics Data System (ADS)

    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

    2015-10-01

    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.

  11. 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

  12. 21 CFR 310.532 - Drug products containing active ingredients offered over-the-counter (OTC) to relieve the...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... offered over-the-counter (OTC) to relieve the symptoms of benign prostatic hypertrophy. 310.532 Section... products containing active ingredients offered over-the-counter (OTC) to relieve the symptoms of benign... the ingredient sabal have been present in over-the-counter (OTC) drug products to relieve the...

  13. 21 CFR 310.532 - Drug products containing active ingredients offered over-the-counter (OTC) to relieve the...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... offered over-the-counter (OTC) to relieve the symptoms of benign prostatic hypertrophy. 310.532 Section... products containing active ingredients offered over-the-counter (OTC) to relieve the symptoms of benign... the ingredient sabal have been present in over-the-counter (OTC) drug products to relieve the...

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

    MedlinePlus

    ... street names: ac/dc, coties, demmies, dillies, hillbilly heroin, o.c., oxy, oxycotton, percs and vics to ... prescription pain relievers is like being hooked on heroin and the withdrawal isn't much different: bone ...

  15. 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)

  16. 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.

  17. Analysis of the HVDC turbine generator torsional interactions

    SciTech Connect

    Padiyar, K.R. . Dept. of Electrical Communication Engineering); Kothari, A.G. )

    1989-01-01

    In the recent past it has been found that HVDC transmission systems and turbine-generator shaft torsional dynamics can interact in an unfavourable manner. This paper presents a detailed linearized state space model of AC/DC system to study this torsional interaction. The model developed is used to study the effect of various system parameters, such as, dc line loading, converter firing angle, the firing scheme employed. The results obtained are compared with those previously given.

  18. 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

  19. Ultrasonic Welding of Plastic Pipes Using Torsional Vibration

    NASA Astrophysics Data System (ADS)

    Masuzawa, Nobuyoshi; Hori, Kiichi; Ide, Masao

    1998-05-01

    In recent years, the application of ultrasonic welding to plastics has become common. In this paper a method for ultrasonic welding of plastic pipes using torsional vibrations is reported. In this method torsional vibrations are applied to the welding pipe from the circumferential direction with horns placed near the welding surface. Static pressure is independently applied from the vibrations to the welding surface. It was observed that acrylic resin pipes could be effectively welded by the proposed method.

  20. Changes in gravitational state cause changes in ocular torsion

    NASA Technical Reports Server (NTRS)

    Diamond, S. G.; Markham, C. H.

    1998-01-01

    Gravity-responsive eye torsion was studied simultaneously in both eyes during parabolic flight to determine the effects of weightlessness. Observed effects were that torsional position of eyes in the 1G states between parabolas was offset from the baseline positions obtained prior to the onset of parabolas, responses to hyper- and hypogravity were seen in most subjects, and responses were consistent within subjects but varied between subjects.

  1. Non-Abelian anomalies on a curved space with torsion

    SciTech Connect

    Cognola, G.; Giacconi, P.

    1989-05-15

    Using path-integral methods and /zeta/-function regularization a nonperturbative derivation of non-Abelian-covariant and consistent anomalies on a curved space with torsion is given. All terms depending on torsion, that one has in the expression of the consistent anomaly, can be eliminated by adding suitable counterterms to the Lagrangian density. In this way, the well-known result of Bardeen is recovered. The so-called ''covariant anomaly'' will be discussed too.

  2. 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

  3. 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.

  4. 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.

  5. Analysis of torsional oscillations using an artificial neural network

    SciTech Connect

    Hsu, Y.Y.; Jeng, L,H. )

    1992-12-01

    In this paper, a novel approach using an artificial neural network (ANN) is proposed for the analysis of torsional oscillations in a power system. In the developed artificial neural network, those system variables such as generator loadings and capacitor compensation ratio which have major impacts on the damping characteristics of torsional oscillatio modes are employed as the inputs. The outputs of the neural net provide the desired eigenvalues for torsional modes. Once the connection weights of the neural network have been learned using a set of training data derived off-line, the neural network can be applied to torsional analysis in real-time situations. To demonstrate the effectiveness of the proposed neural net, torsional analysis is performed on the IEEE First Benchmark Model. It is concluded from the test results that accurate assessment of the torsional mode eigenvalues can be achieved by the neural network in a very efficient manner. Thereofore, the proposed neural network approach can serve as a valuable tool to system operators in conducting SSR analysis in operational planning.

  6. A nationwide epidemiological study of testicular torsion in Korea.

    PubMed

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

    2014-12-01

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

  7. A new hybrid longitudinal-torsional magnetostrictive ultrasonic transducer

    NASA Astrophysics Data System (ADS)

    Karafi, Mohammad Reza; Hojjat, Yousef; Sassani, Farrokh

    2013-06-01

    In this paper, a novel hybrid longitudinal-torsional magnetostrictive ultrasonic transducer (HL-TMUT) is introduced. The transducer is composed of a magnetostrictive exponential horn and a stainless steel tail mass. In this transducer a spiral magnetic field made up of longitudinal and circumferential magnetic fields is applied to the magnetostrictive horn. As a result, the magnetostrictive horn oscillates simultaneously both longitudinally and torsionally in accordance with the Joule and Wiedemann effects. The magnetostrictive exponential horn is designed in such a manner that it has the same longitudinal and torsional resonant frequency. It is made up of ‘2V Permendur’, which has isotropic magnetic properties. The differential equations of the torsional and longitudinal vibration of the horn are derived, and a HL-TMUT is designed with a resonant frequency of 20 573 Hz. The natural frequency and mode shapes of the transducer are considered theoretically and numerically. The experimental results show that this transducer resonates torsionally and longitudinally with frequencies of 20 610 Hz and 20 830 Hz respectively. The maximum torsional displacement is 1.5 mrad m-1 and the maximum longitudinal displacement is 0.6 μm. These are promising features for industrial applications.

  8. 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. PMID:25903461

  9. 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.

  10. Dispersion and phase shifts of torsional waves in forward models

    NASA Astrophysics Data System (ADS)

    Cox, G. A.; Livermore, P. W.; Mound, J. E.

    2013-12-01

    Torsional Alfvén waves have been thought to exist in the Earth's core since their theoretical prediction by Braginsky in 1970. More recently, they have been inferred from observations of secular variation and length of day, and also observed in geodynamo simulations. These inferences from geophysical data have provided an important means of estimating core properties such as viscosity and internal magnetic field strength. We produce 1D forward models of torsional waves in the Earth's core, also known as torsional oscillations, and study their evolution in a cylinder, a full sphere and an equatorially symmetric spherical shell. The key features of torsional waves in our models are: geometric dispersion, phase shifts and internal reflections. In all three core geometries, we find that travelling torsional waves undergo significant geometric dispersion that increases with successive reflections from the boundaries such that an initial wave pulse becomes unidentifiable within three transits of the core. This dispersion partly arises due to low amplitude wakes trailing behind sharply defined pulses during propagation, a phenomenon that is linked to the failure of Huygens' principle in the geometric setting of torsional waves. We investigate the relationship between geometric dispersion and wavelength, concluding that long wavelength features are more dispersive than short wavelength features. This result is particularly important because torsional waves inferred from secular variation are relatively long wavelength, and are therefore likely to undergo significant dispersion within the Earth's core. Torsional waves in all three geometries are reflected at the equator of the core-mantle boundary with the same sign as the incident wave, but display more complicated behaviour at the rotation axis. In a cylindrical core, the analytic solutions to the torsional wave equation are known. We use these to derive an expression for the phase shift that torsional waves undergo upon

  11. Revealing the competition between peeled ssDNA, melting bubbles, and S-DNA during DNA overstretching by single-molecule calorimetry

    PubMed Central

    Zhang, Xinghua; Chen, Hu; Le, Shimin; Rouzina, Ioulia; Doyle, Patrick S.; Yan, Jie

    2013-01-01

    Double-stranded DNA (dsDNA) unconstrained by torsion undergoes an overstretching transition at about 65 pN, elongating the DNA to about 1.7-fold. Three possible structural transitions have been debated for the nature of DNA overstretching: (i) “peeling” apart of dsDNA to produce a peeled ssDNA strand under tension while the other strand coils, (ii) “inside-strand separation” of dsDNA to two parallel ssDNA strands that share tension (melting bubbles), and (iii) “B-to-S” transition to a novel dsDNA, termed S-DNA. Here we overstretched an end-opened DNA (with one open end to allow peeling) and an end-closed (i.e., both ends of the linear DNA are covalently closed to prohibit peeling) and torsion-unconstrained DNA. We report that all three structural transitions exist depending on experimental conditions. For the end-opened DNA, the peeling transition and the B-to-S transition were observed; for the end-closed DNA, the inside-strand separation and the B-to-S transition were observed. The peeling transition and the inside-strand separation are hysteretic and have an entropy change of approximately 17 cal/(K⋅mol), whereas the B-to-S transition is nonhysteretic and has an entropy change of approximately −2 cal/(K⋅mol). The force-extension curves of peeled ssDNA, melting bubbles, and S-DNA were characterized by experiments. Our results provide experimental evidence for the formation of DNA melting bubbles driven by high tension and prove the existence of nonmelted S-DNA. Our findings afford a full understanding of three possible force-driven structural transitions of torsion-unconstrained DNA and the resulting three overstretched DNA structures. PMID:23431154

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

    NASA Astrophysics Data System (ADS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1992-06-01

    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.

  13. Direct torsional actuation of microcantilevers using magnetic excitation

    SciTech Connect

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Acedo, Luis

    2015-11-01

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

  15. 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.

  16. Torsional Deformations in Subnanometer MoS Interconnecting Wires.

    PubMed

    Koh, Ai Leen; Wang, Shanshan; Ataca, Can; Grossman, Jeffrey C; Sinclair, Robert; Warner, Jamie H

    2016-02-10

    We use aberration-corrected transmission electron microscopy to track the real time atomic level torsional dynamics of subnanometer wires of MoS interconnecting monolayer regions of MoS2. An in situ heating holder is used inside the transmission electron microscope to raise the temperature of the sample to 400 °C to increase crystallization rates of the wires and reduce contamination effects. Frequent rotational twisting of the MoS wire is captured, demonstrating elastic torsional deformation of the MoS wires. We show that torsional rotations of the crystal structure of the MoS wires depend upon the specific atomic structure of the anchored sections of the suspended wire and the number of unit cells that make up the wire length. Elastic torsional flexibility of the MoS wires is revealed to help their self-adapting connectivity during the structural changes. Plastic torsional deformation is also seen for MoS wires that contain defects in their crystal structure, which produce small scale rotational disorder within the wires. Upon removal of the defects, the wire returns back to pristine form. These results provide detailed insights into how the atomic structure of the anchoring site significantly influences the nanowire configurations relative to the monolayered MoS2. PMID:26785319

  17. Simple torsion test for shear moduli determination of orthotropic composites

    NASA Technical Reports Server (NTRS)

    Sumsion, H. T.; Rajapakse, Y. D. S.

    1978-01-01

    By means of torsion tests performed on test specimens of the same material having a minimum of two different cross sections (flat sheet of different widths), the effective in-plane (G13) and out-of-plane (G23) shear moduli were determined for two composite materials of uniaxial and angleply fiber orientations. Test specimens were 16 plies (nominal 2 mm) thick, 100 mm in length, and in widths of 6.3, 9.5, 12.5, and 15.8 mm. Torsion tests were run under controlled deflection (constant angle of twist) using an electrohydraulic servocontrolled test system. In-plane and out-of-plane shear moduli were calculated from an equation derived in the theory of elasticity which relates applied torque, the torsional angle of twist, the specimen width/thickness ratio, and the ratio of the two shear moduli G13/G23. Results demonstrate that torsional shear moduli, G23 as well as G13, can be determined by simple torsion tests of flat specimens of rectangular cross section. Neither the uniaxial nor angleply composite material were transversely isotropic.

  18. A Rare Cause of Placental Abruption: Uterine Torsion

    PubMed Central

    Güneş, Muhammed Siraç; Kiran, Gürkan; Gülşen, Mehmet Serdar

    2016-01-01

    Uterine torsion is defined as a rotation on its long axis and it is a dangerous, unexpected obstetric emergency. We report a case of uterine torsion at 32 weeks of gestation in a singleton pregnancy. A 37-year-old woman with multiple prior cesarean deliveries referred to emergency unit of our hospital at 32 weeks of gestation with severe abdominal pain and mild vaginal bleeding. Ultrasonography showed a single fetus in vertex position, with a normal amniotic fluid. Fetal biometer was appropriate for 32 weeks of gestation. Placental location was anterior with a subchorionic hypoechogenic small area which was suspected to be a sign of placental abruption. An emergency cesarean section was performed under general anesthesia. The 180° uterine torsion was diagnosed and it was not possible to perform detorsion of the gravid uterus by exteriorization by pfannenstiel incision. Posterior hysterotomy was performed and a male baby of 1830 grams weight was delivered. The newborn was transported to Neonatal Intensive Care Unit (NICU) of another hospital and discharged within two weeks. Patient recovered well and was discharged on second postoperation day. Uterine torsion is a very rare and life threatening situation. In unexpected cases posterior low transuerse hysterotomy is generally performed and it is suggested as a safe choice when detorsion was not accomplished. It is not easy to keep in mind the possibility of uterine torsion in cases of abdominal pain during pregnancy. Because it generally causes abruption, management of abruption is vitally important to prevent fetal mortality. PMID:26894131

  19. [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. PMID:27583079

  20. 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.

  1. 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

  2. [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. PMID:26054155

  3. Torsion of Flanged Members with Cross Sections Restrained Against Warping

    NASA Technical Reports Server (NTRS)

    Hill, H N

    1943-01-01

    The longitudinal stresses and the stiffness of flange members - I-beams, channels, and Z-bars - were investigated when these members were subjected to torque with constraint against cross-sectional warping. Measured angles of rotation agreed with corresponding calculated values in which the torsion bending factor of the cross section was involved; the agreement was better for the I-beam and the Z-bar than for the channel. Longitudinal stresses measured at the mid-span were found to agree with the calculated values that involved unit warping as well as the torsion-bending factors: the channel showed the greatest discrepancy between measured and calculated values. When commonly given expressions for rotations and maximum longitudinal stresses in a twisted I-beam were applied to the channel and to the Z-bar, values were obtained that were in reasonably good agreement with values obtained by the method of torsion-bending constant and unit warping.

  4. Testicular torsion and the acute scrotum: current emergency management.

    PubMed

    Ta, Anthony; D'Arcy, Frank T; Hoag, Nathan; D'Arcy, John P; Lawrentschuk, Nathan

    2016-06-01

    The acute scrotum is a challenging condition for the treating emergency physician requiring consideration of a number of possible diagnoses including testicular torsion. Prompt recognition of torsion and exclusion of other causes may lead to organ salvage, avoiding the devastating functional and psychological issues of testicular loss and minimizing unnecessary exploratory surgeries. This review aims to familiarize the reader with the latest management strategies for the acute scrotum, discusses key points in diagnosis and management and evaluates the strengths and drawbacks of history and clinical examination from an emergency perspective. It outlines the types and mechanisms of testicular torsion, and examines the current and possible future roles of labwork and radiological imaging in diagnosis. Emergency departments should be wary of younger males presenting with the acute scrotum. PMID:26267075

  5. 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

  6. Torsional vibration transmissibility characteristics of reinforced viscoelastic flexible pipes

    NASA Astrophysics Data System (ADS)

    Kennedy, I.; Tomlinson, G. R.

    1988-04-01

    The dynamic complex shear moduli of fibre and steel reinforced viscoelastic flexible pipes are determined by using a torsional non-resonance method. Material property master curves as a function of frequency and temperature are obtained by using reduced modulus methods. In situations where the loss factor data is difficult to measure directly it is shown that these data can be obtained from the modulus data by using a stepwise Hilbert transform technique. Predictions of the torsional vibration transmissibility of reinforced pipes, by using a simple theory in conjunction with the material properties, results in a close comparison with experimental measurements of the torsional vibration transmissibility characteristics of the pipes over a wide frequency range.

  7. 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.

  8. The axial-torsional vibration of pretwisted beams

    NASA Astrophysics Data System (ADS)

    Liu, Kuang-Chen; Friend, James; Yeo, Leslie

    2009-03-01

    We investigate the coupled axial-torsional vibration of pretwisted beams. The equations of motion governing the extension, torsion, and cross-sectional warping of pretwisted beams are derived from Hamiltons principle, and the common assumptions used to simplify the equations are carefully examined through scaling analysis. Inconsistencies in previous works—such as the neglect of spatial and time derivatives of torsion in the Lagrangian functional—are remedied, giving rise to fourth-order terms in the equations of motion that are significant for higher harmonics. Furthermore, scaling analysis of the governing equations yields a set of objective criteria for checking the validity of the frequently misused assumption that the warping function under pretwist is locally identical to that of a prismatic beam; we show that this simplification is responsible for the common poor prediction of axial resonance frequencies for pretwisted beams.

  9. Incorporation of another person's limb into body image relieves phantom limb pain: a case study.

    PubMed

    Weeks, Sharon R; Tsao, Jack W

    2010-12-01

    Phantom limb phenomena are well characterized, but the underlying mechanisms remain unclear. Here we report a patient who relieves his phantom sensations and pain, experienced as itching and cramping, through scratching or massaging his prosthesis or the leg of another person. This pain relief occurs only when phantom limb sensations are present. We hypothesize that symptom relief results from incorporation of the foreign limb into the patient's body image, mediated by the sensory mirror neuron system, relieving pain by restoring concordance between sensory systems. PMID:20425663

  10. 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.