Vibration of Elastic Functionally Graded Thick Rings

Directory of Open Access Journals (Sweden)

Guang-Hui Xu

2017-01-01

Full Text Available The free vibration behaviors of functionally graded rings were investigated theoretically. The material graded in the thickness direction according to the power law rule and the rings were assumed to be in plane stress and plane strain states. Based on the first-order shear deformation theory and the kinetic relation of von Kárman type, the frequency equation for free vibration of functionally graded ring was derived. The derived results were verified by those in literatures which reveals that the present theory can be appropriate to predict the free vibration characteristics for quite thick rings with the radius-to-thickness ratio from 60 down to 2.09. Comparison between the plane stress case and the plane strain case indicates a slight difference. Meanwhile, the effects of the structural dimensional parameters and the material inhomogeneous parameter are examined. It is interesting that the value of the logarithmic form of vibration frequency is inversely proportional to the logarithmic form of the radius-to-thickness ratio or the mean radius.

Ring tests on high density polyethylene: Full investigation assisted by finite element modeling

International Nuclear Information System (INIS)

Laiarinandrasana, L.; Devilliers, C.; Oberti, S.; Gaudichet, E.; Fayolle, B.; Lucatelli, J.M.

2011-01-01

In order to characterize the mechanical behavior of HDPE pipes, the ASTM D 2290-04 standard recommends carrying out tensile tests on notched rings, cut out from the pipe. This very simple test is also utilized to investigate the aging effect of the pipe by determining the strain at failure. Comparison between full ring and notched ring mechanical responses are discussed. Constitutive modeling including strain rate effects was performed by finite element analysis. This allowed a better understanding of the stress state in the cross section perpendicular to the loading direction. Additionally, the influence of a thin layer of oxidized HDPE in the inner wall of the ring was studied in the light of the finite element results.

Quantification of Applied Stresses of C-Ring Specimens for Stress Corrosion Cracking Tests

International Nuclear Information System (INIS)

Kim, Woo Gon; Kim, Sun Jae; Rhee, Chang Kyu; Kuk, Il Hiun; Choi, Jong Ho

1997-01-01

For comparing their resistances for stress-corrosion cracking(SCC) in the K600-MA, K690-MA, and K600-TT tubes, C-ring specimens were fabricated with the various thermal-treatments to control the distributions of the precipitates like Cr-carbides. The bending stresses were analyzed to determine the amounts to make the stress quantitatively to all the C-ring samples, and then the stresses were calculated with the relation to the outer diameter(O.D) deflection(δ) of the C-rings. To measure accurately the bending strains of the C-ring specimens, the strain gauges were used and the compression test was also carried out. In the elastic region, the stresses in both the transverse and the circumferential directions were different with the locations of the strain gauges as attached at α= 30 .deg., 45 .deg., and 90 .deg. to the principal stress direction, but those in the longitudinal direction were independent of their attached locations. Calculated stresses from the strains obtained using the strain gauges were well agreed with the theoretical. In the plastic region over δ=1.0mm, the stresses for the TT tubes showed lower values of about 400MPa than those for the MA tubes. However, the stresses among the TT tubes showed almost the similar values in this region. Therefore, the states of the stresses applied to the C-ring specimens would be different with the material conditions, i.e, the chemical compositions, the thermal treatments such as MA and TT

Benz[a]anthracene Biotransformation and Production of Ring Fission Products by Sphingobium sp. Strain KK22

Science.gov (United States)

Kunihiro, Marie; Ozeki, Yasuhiro; Nogi, Yuichi; Hamamura, Natsuko

2013-01-01

A soil bacterium, designated strain KK22, was isolated from a phenanthrene enrichment culture of a bacterial consortium that grew on diesel fuel, and it was found to biotransform the persistent environmental pollutant and high-molecular-weight polycyclic aromatic hydrocarbon (PAH) benz[a]anthracene. Nearly complete sequencing of the 16S rRNA gene of strain KK22 and phylogenetic analysis revealed that this organism is a new member of the genus Sphingobium. An 8-day time course study that consisted of whole-culture extractions followed by high-performance liquid chromatography (HPLC) analyses with fluorescence detection showed that 80 to 90% biodegradation of 2.5 mg liter−1 benz[a]anthracene had occurred. Biodegradation assays where benz[a]anthracene was supplied in crystalline form (100 mg liter−1) confirmed biodegradation and showed that strain KK22 cells precultured on glucose were equally capable of benz[a]anthracene biotransformation when precultured on glucose plus phenanthrene. Analyses of organic extracts from benz[a]anthracene biodegradation by liquid chromatography negative electrospray ionization tandem mass spectrometry [LC/ESI(−)-MS/MS] revealed 10 products, including two o-hydroxypolyaromatic acids and two hydroxy-naphthoic acids. 1-Hydroxy-2- and 2-hydroxy-3-naphthoic acids were unambiguously identified, and this indicated that oxidation of the benz[a]anthracene molecule occurred via both the linear kata and angular kata ends of the molecule. Other two- and single-aromatic-ring metabolites were also documented, including 3-(2-carboxyvinyl)naphthalene-2-carboxylic acid and salicylic acid, and the proposed pathways for benz[a]anthracene biotransformation by a bacterium were extended. PMID:23686261

A Stereoselective [3+1] Ring Expansion for the Synthesis of Highly Substituted Methylene Azetidines.

Science.gov (United States)

Schmid, Steven C; Guzei, Ilia A; Schomaker, Jennifer M

2017-09-25

The reaction of rhodium-bound carbenes with strained bicyclic methylene aziridines results in a formal [3+1] ring expansion to yield highly substituted methylene azetidines with excellent regio- and stereoselectivity. The reaction appears to proceed through an ylide-type mechanism, where the unique strain and structure of the methylene aziridine promotes a ring-opening/ring-closing cascade that efficiently transfers chirality from substrate to product. The resultant products can be elaborated into new azetidine scaffolds containing vicinal tertiary-quaternary and even quaternary-quaternary stereocenters. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A thermal active restrained shrinkage ring test to study the early age concrete behaviour of massive structures

International Nuclear Information System (INIS)

Briffaut, M.; Benboudjema, F.; Torrenti, J.M.; Nahas, G.

2011-01-01

In massive concrete structures, cracking may occur during hardening, especially if autogenous and thermal strains are restrained. The concrete permeability due to this cracking may rise significantly and thus increase leakage (in tank, nuclear containment...) and reduce the durability. The restrained shrinkage ring test is used to study the early age concrete behaviour (delayed strains evolution and cracking). This test shows, at 20 o C and without drying, for a concrete mix which is representative of a French nuclear power plant containment vessel (w/c ratio equal to 0.57), that the amplitude of autogenous shrinkage (about 40 μm/m for the studied concrete mix) is not high enough to cause cracking. Indeed, in this configuration, thermal shrinkage is not significant, whereas this is a major concern for massive structures. Therefore, an active test has been developed to study cracking due to restrained thermal shrinkage. This test is an evolution of the classical restrained shrinkage ring test. It allows to take into account both autogenous and thermal shrinkages. Its principle is to create the thermal strain effects by increasing the temperature of the brass ring (by a fluid circulation) in order to expand it. With this test, the early age cracking due to restrained shrinkage, the influence of reinforcement and construction joints have been experimentally studied. It shows that, as expected, reinforcement leads to an increase of the number of cracks but a decrease of crack widths. Moreover, cracking occurs preferentially at the construction joint.

Resonant tunneling measurements of size-induced strain relaxation

Science.gov (United States)

Akyuz, Can Deniz

Lattice mismatch strain available in such semiconductor heterostructures as Si/SiGe or GaAs/AlGaAs can be employed to alter the electronic and optoelectronic properties of semiconductor structures and devices. When deep submicron structures are fabricated from strained material, strained layers relax by sidewall expansion giving rise to size- and geometry-dependent strain gradients throughout the structure. This thesis describes a novel experimental technique to probe the size-induced strain relaxation by studying the tunneling current characteristics of strained p-type Si/SiGe resonant tunneling diodes. Our current-voltage measurements on submicron strained p-Si/SiGe double- and triple-barrier resonant tunneling structures as a function of device diameter, D, provide experimental access to both the average strain relaxation (which leads to relative shifts in the tunneling current peak positions) and strain gradients (which give rise to a fine structure in the current peaks due to inhomogeneous strain-induced lateral quantization). We find that strain relaxation is significant, with a large fraction of the strain energy relaxed on average in D ≤ 0.25 m m devices. Further, the in-plane potentials that arise from inhomogeneous strain gradients are large. In the D ˜ 0.2 m m devices, the corresponding lateral potentials are approximately parabolic exceeding ˜ 25 meV near the perimeter. These potentials create discrete hole states in double-barrier structures (single well), and coupled hole states in triple-barrier structures (two wells). Our results are in excellent agreement with finite-element strain calculations in which the strained layers are permitted to relax to a state of minimum energy by sidewall expansion. Size-induced strain relaxation will undoubtedly become a serious technological issue once strained devices are scaled down to the deep submicron regime. Interestingly, our calculations predict and our measurements are consistent with the appearance of

Deformation of the dog aortic valve ring during the cardiac cycle

NARCIS (Netherlands)

van Renterghem, R.J.; Steenhoven, van A.A.; Arts, M.G.J.; Reneman, R.S.

1988-01-01

Changes in strain in the line of aortic valve leaflet attachment (aortic ring) were measured during the cardiac cycle by means of an inductive technique. To that purpose coils were sutured to each commissure and base point of the aortic ring, when the animals were on a cardiopulmonary bypass. After

Silicon photonic micro-ring resonators to sense strain and ultrasound

NARCIS (Netherlands)

Westerveld, W.J.

2014-01-01

We demonstrated that photonic micro-ring resonators can be used in micro-machined ultrasound microphones. This might cause a breakthrough in array transducers for ultrasonography; first because optical multiplexing allows array interrogation via one optical fiber and second because the

Prognostic Significance of Signet Ring Gastric Cancer

Science.gov (United States)

Taghavi, Sharven; Jayarajan, Senthil N.; Davey, Adam; Willis, Alliric I.

2012-01-01

Purpose Studies in Asia have questioned the dictum that signet ring cell carcinoma (SRC) has a worse prognosis than other forms of gastric cancer. Our study determined differences in presentation and outcomes between SRC and gastric adenocarcinoma (AC) in the United States. Patients and Methods The National Cancer Institute Surveillance, Epidemiology, and End Results database was reviewed for SRC and AC from 2004 to 2007. Results We reviewed 10,246 cases of patients with gastric cancer, including 2,666 of SRC and 7,580 of AC. SRC presented in younger patients (61.9 v 68.7 years; P < .001) and less often in men (52.7% v 68.7%; P < .001). SRC patients were more frequently black (11.3% v 10.9%), Asian (16.4% v 13.2%), American Indian/Alaska Native (0.9% v 0.8%), or Hispanic (23.3% v 14.0%; P < .001). SRC was more likely to be stage T3-4 (45.8% v 33.3%), have lymph node spread (59.7% v 51.8%), and distant metastases (40.2% v 37.6%; P < .001). SRC was more likely to be found in the lower (30.7% v 24.2%) and middle stomach (30.6% v 20.7%; P < .001). Median survival was not different between the two (AC, 14.0 months v SRC, 13.0 months; P = .073). Multivariable analyses demonstrated SRC was not associated with mortality (hazard ratio [HR], 1.05; 95% CI, 0.96 to 1.11; P = .150). Mortality was associated with age (HR, 1.01; 95% CI, 1.01 to 1.02; P < .001), black race (HR, 1.10; 95% CI, 1.01 to 1.20; P = .026), and tumor grade. Variables associated with lower mortality risk included Asian race (HR, 0.83; 95% CI, 0.77 to 0.91; P < .001) and surgery (HR, 0.37; 95% CI, 0.34 to 0.39; P < .001). Conclusion In the United States, SRC significantly differs from AC in extent of disease at presentation. However, when adjusted for stage, SRC does not portend a worse prognosis. PMID:22927530

Ordered quantum-ring chains grown on a quantum-dot superlattice template

International Nuclear Information System (INIS)

Wu Jiang; Wang, Zhiming M.; Holmes, Kyland; Marega, Euclydes; Mazur, Yuriy I.; Salamo, Gregory J.

2012-01-01

One-dimensional ordered quantum-ring chains are fabricated on a quantum-dot superlattice template by molecular beam epitaxy. The quantum-dot superlattice template is prepared by stacking multiple quantum-dot layers and quantum-ring chains are formed by partially capping quantum dots. Partially capping InAs quantum dots with a thin layer of GaAs introduces a morphological change from quantum dots to quantum rings. The lateral ordering is introduced by engineering the strain field of a multi-layer InGaAs quantum-dot superlattice.

Tuning strain of granular matter by basal assisted Couette shear

Directory of Open Access Journals (Sweden)

Zhao Yiqiu

2017-01-01

Full Text Available We present a novel Couette shear apparatus capable of generating programmable azimuthal strain inside 2D granular matter under Couette shear. The apparatus consists of 21 independently movable concentric rings and two boundary wheels with frictional racks. This makes it possible to quasistatically shear the granular matter not only from the boundaries but also from the bottom. We show that, by specifying the collective motion of wheels and rings, the apparatus successfully generates the desired strain profile inside the sample granular system, which is composed of about 2000 photoelastic disks. The motion and stress of each particle is captured by an imaging system utilizing reflective photoelasticimetry. This apparatus provides a novel method to investigate shear jamming properties of granular matter with different interior strain profiles and unlimited strain amplitudes.

Study of improvement in 1st ring`s gas-seal; Top ring no gas seal seino kojo no kento

Energy Technology Data Exchange (ETDEWEB)

Ando, H; Tateishi, Y; Fujimura, K; Hitosugi, H [Nippon Piston Ring Co. Ltd., Tokyo (Japan)

1997-10-01

The authors studied the effect of an angle of 1st ring twist on the amount of blow-by concerning higher speed/higher output engines for motorcycles. As a result, the authors found the twist made the ring restrained in a ring groove of piston , and confirmed its suitable range for blow-by. By means of the developed optimization method, the authors have achieved significant reduction in blow-by at high engine speed. 1 ref., 9 figs., 2 tabs.

Stretchable Complementary Split Ring Resonator (CSRR-Based Radio Frequency (RF Sensor for Strain Direction and Level Detection

Directory of Open Access Journals (Sweden)

Seunghyun Eom

2016-10-01

Full Text Available In this paper, we proposed a stretchable radio frequency (RF sensor to detect strain direction and level. The stretchable sensor is composed of two complementary split ring resonators (CSRR with microfluidic channels. In order to achieve stretchability, liquid metal (eutectic gallium-indium, EGaIn and Ecoflex substrate are used. Microfluidic channels are built by Ecoflex elastomer and microfluidic channel frames. A three-dimensional (3D printer is used for fabrication of microfluidic channel frames. Two CSRR resonators are designed to resonate 2.03 GHz and 3.68 GHz. When the proposed sensor is stretched from 0 to 8 mm along the +x direction, the resonant frequency is shifted from 3.68 GHz to 3.13 GHz. When the proposed sensor is stretched from 0 to 8 mm along the −x direction, the resonant frequency is shifted from 2.03 GHz to 1.78 GHz. Therefore, we can detect stretched length and direction from independent variation of two resonant frequencies.

The Plasmodium PI(4)K inhibitor KDU691 selectively inhibits dihydroartemisinin-pretreated Plasmodium falciparum ring-stage parasites.

Science.gov (United States)

Dembele, L; Ang, X; Chavchich, M; Bonamy, G M C; Selva, J J; Lim, M Yi-Xiu; Bodenreider, C; Yeung, B K S; Nosten, F; Russell, B M; Edstein, M D; Straimer, J; Fidock, D A; Diagana, T T; Bifani, P

2017-05-24

Malaria control and elimination are threatened by the emergence and spread of resistance to artemisinin-based combination therapies (ACTs). Experimental evidence suggests that when an artemisinin (ART)-sensitive (K13 wild-type) Plasmodium falciparum strain is exposed to ART derivatives such as dihydroartemisinin (DHA), a small population of the early ring-stage parasites can survive drug treatment by entering cell cycle arrest or dormancy. After drug removal, these parasites can resume growth. Dormancy has been hypothesized to be an adaptive physiological mechanism that has been linked to recrudescence of parasites after monotherapy with ART and, possibly contributes to ART resistance. Here, we evaluate the in vitro drug sensitivity profile of normally-developing P. falciparum ring stages and DHA-pretreated dormant rings (DP-rings) using a panel of antimalarial drugs, including the Plasmodium phosphatidylinositol-4-OH kinase (PI4K)-specific inhibitor KDU691. We report that while KDU691 shows no activity against rings, it is highly inhibitory against DP-rings; a drug effect opposite to that of ART. Moreover, we provide evidence that KDU691 also kills DP-rings of P. falciparum ART-resistant strains expressing mutant K13.

Transformation of self-assembled InAs/InP quantum dots into quantum rings without capping.

Science.gov (United States)

Sormunen, Jaakko; Riikonen, Juha; Mattila, Marco; Tiilikainen, Jouni; Sopanen, Markku; Lipsanen, Harri

2005-08-01

Transformation of self-assembled InAs quantum dots (QDs) on InP(100) into quantum rings (QRs) is studied. In contrast to the typical approach to III--V semiconductor QR growth, the QDs are not capped to form rings. Atomic force micrographs reveal a drastic change from InAs QDs into rings after a growth interruption in tertiarybutylphosphine ambient. Strain energy relief in the InAs QD is discussed and a mechanism for dot-to-ring transformation by As/P exchange reactions is proposed.

Optimization and Simulation of Machining Parameters in Radial-axial Ring Rolling Process

Directory of Open Access Journals (Sweden)

Shuiyuan Tang

2011-05-01

Full Text Available Ring rolling is a complicated process, in which rolling parameters influence directly the quality of ring. It is a process method with high productivity and few waste of material, widely used in transportation industry including automotive, shipbuilding, aerospace etc. During the rolling process of large-sized parts, crinkle and hollows often appear on surface, due to inconsistence of rolling motions with the deformation of ring part. Based on radial-axial ring rolling system configuration, motions and forces in rolling process are analyzed, and a dynamic model is formulated. Error of ring's end flatness and roundness are defined as the characteristic parameters of ring quality. The relationship between core roller feed speed, drive roller speed, the upper taper roller feed speed, and quality of ring part are analyzed. The stress and strain of the part are simulated in the Finite Element Method by DEFORM software. The simulation results provide a reference for the definition of ring rolling process parameters. It is able to make the deformation of the part be consistent with the process parameters, and improve product quality considerably.

Re-examination of cellular cyclic beta-1,2-glucans of Rhizobiaceae: distribution of ring sizes and degrees of glycerol-1-phosphate substitution.

Science.gov (United States)

Zevenhuizen, L P; van Veldhuizen, A; Fokkens, R H

1990-04-01

Gel-filtration and thin layer chromatography of low molecular weight carbohydrates from culture filtrates of Agrobacterium radiobacter, Isolate II, have shown, that next to the neutral beta-1,2-glucan fraction a major acidic fraction was present which was found to be glycerophosphorylated cyclic beta-1,2-glucans. Re-examination of cyclic beta-1,2-glucan preparations which had been obtained by extraction of Rhizobium cells with hot phenol-water also showed these acidic modified beta-1,2-glucans to be present. Cyclic beta-1,2-glucans from R. leguminosarum (9 strains) and of R. phaseoli (1 strain) had ring size distribution with degrees of polymerisation (DPs) of 19 and 20 as major ring sizes of which a minor part was glycerophosphorylated; beta-1,2-glucans of R. trifolii (3 strains) had ring sizes with DPs measuring 19-22 as prominent components which were largely unsubstituted, and R. meliloti (7 strains) had beta-1,2-glucans with ring size distributions extending to still higher DPs of 19-25 of which the major part appeared to be glycerophosphorylated.

Spatio-temporal dynamics of an active, polar, viscoelastic ring.

Science.gov (United States)

Marcq, Philippe

2014-04-01

Constitutive equations for a one-dimensional, active, polar, viscoelastic liquid are derived by treating the strain field as a slow hydrodynamic variable. Taking into account the couplings between strain and polarity allowed by symmetry, the hydrodynamics of an active, polar, viscoelastic body include an evolution equation for the polarity field that generalizes the damped Kuramoto-Sivashinsky equation. Beyond thresholds of the active coupling coefficients between the polarity and the stress or the strain rate, bifurcations of the homogeneous state lead first to stationary waves, then to propagating waves of the strain, stress and polarity fields. I argue that these results are relevant to living matter, and may explain rotating actomyosin rings in cells and mechanical waves in epithelial cell monolayers.

A Feeding Strategy in Inner L-Shape Ring Hot Rolling Process

Directory of Open Access Journals (Sweden)

Wen Meng

2017-01-01

Full Text Available In order to make the inner L-shape ring polling process with a closed die structure (ILRRCDS on the top and bottom of the driven roll stable, at first, this paper established the mathematical model for ILRRCDS. Then, the plastic penetration and biting-in conditions for ILRRCDS were deduced based on plain ring rolling theory. Moreover, a feeding strategy that can realize a constant growth of the ring’s outer radius was proposed and the reasonable value ranges of the feed rate of the mandrel were determined. The numerical simulation model for ILRRCDS is established based on ABAQUS software. Finally, the equivalent plastic strain (PEEQ and temperature distributions of rolled ring were obtained. The results indicated that the proposed feeding strategy can realize a stable ILRRCDS. At the end of ILRRCDS, the PEEQ at the inner radius surface of the ring is maximum, the PEEQ at the outer radius surface of the ring takes the second place, and the PEEQ at the middle part of ring is minimum. With the increase of rolling time, the higher temperature zone of the rolled ring gradually moves from the center part of the ring to the “inner corner zone” of the ring.

Electronic and excitonic properties of self-assembled semiconductor quantum rings

NARCIS (Netherlands)

Fomin, V.M.; Gladilin, V.N.; Devreese, J.T.; Blokland, J.H.; Christianen, P.C.M.; Maan, J.C.; Taboada, A.G.; Granados, D.; Garcia, J.M.; Kleemans, N.A.J.M.; Genuchten, van H.C.M.; Bozkurt, M.; Koenraad, P.M.; Wixforth, A.; Lorke, A.

2009-01-01

Theoretical analysis of the electron energy spectrum and the magnetization in a strained InxGa1-xAs/GaAs selfassembled quantum ring (SAQR) is performed using realistic parameters, determined from the cross-sectional scanning-tunneling microscopy characterization. The Aharonov-Bohm oscillations in

Optimization Technology of the LHS-1 Strain for Degrading Gallnut Water Extract and Appraisal of Benzene Ring Derivatives from Fermented Gallnut Water Extract Pyrolysis by Py-GC/MS

Directory of Open Access Journals (Sweden)

Chengzhang Wang

2017-12-01

Full Text Available Gallnut water extract (GWE enriches 80~90% of gallnut tannic acid (TA. In order to study the biodegradation of GWE into gallic acid (GA, the LHS-1 strain, a variant of Aspergillus niger, was chosen to determine the optimal degradation parameters for maximum production of GA by the response surface method. Pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS was first applied to appraise benzene ring derivatives of fermented GWE (FGWE pyrolysis by comparison with the pyrolytic products of a tannic acid standard sample (TAS and GWE. The results showed that optimum conditions were at 31 °C and pH of 5, with a 50-h incubation period and 0.1 g·L−1 of TA as substrate. The maximum yields of GA and tannase were 63~65 mg·mL−1 and 1.17 U·mL−1, respectively. Over 20 kinds of compounds were identified as linear hydrocarbons and benzene ring derivatives based on GA and glucose. The key benzene ring derivatives were 3,4,5-trimethoxybenzoic acid methyl ester, 3-methoxy-1,2-benzenediol, and 4-hydroxy-3,5-dimethoxy-benzoic acid hydrazide.

Optimization Technology of the LHS-1 Strain for Degrading Gallnut Water Extract and Appraisal of Benzene Ring Derivatives from Fermented Gallnut Water Extract Pyrolysis by Py-GC/MS.

Science.gov (United States)

Wang, Chengzhang; Li, Wenjun

2017-12-20

Gallnut water extract (GWE) enriches 80~90% of gallnut tannic acid (TA). In order to study the biodegradation of GWE into gallic acid (GA), the LHS-1 strain, a variant of Aspergillus niger , was chosen to determine the optimal degradation parameters for maximum production of GA by the response surface method. Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) was first applied to appraise benzene ring derivatives of fermented GWE (FGWE) pyrolysis by comparison with the pyrolytic products of a tannic acid standard sample (TAS) and GWE. The results showed that optimum conditions were at 31 °C and pH of 5, with a 50-h incubation period and 0.1 g·L -1 of TA as substrate. The maximum yields of GA and tannase were 63~65 mg·mL -1 and 1.17 U·mL -1 , respectively. Over 20 kinds of compounds were identified as linear hydrocarbons and benzene ring derivatives based on GA and glucose. The key benzene ring derivatives were 3,4,5-trimethoxybenzoic acid methyl ester, 3-methoxy-1,2-benzenediol, and 4-hydroxy-3,5-dimethoxy-benzoic acid hydrazide.

Self-organized formation of GaSb/GaAs quantum rings.

Science.gov (United States)

Timm, R; Eisele, H; Lenz, A; Ivanova, L; Balakrishnan, G; Huffaker, D L; Dähne, M

2008-12-19

Ring-shaped GaSb/GaAs quantum dots, grown by molecular beam epitaxy, were studied using cross-sectional scanning tunneling microscopy. These quantum rings have an outer shape of a truncated pyramid with baselengths around 15 nm and heights of about 2 nm but are characterized by a clear central opening extending over about 40% of the outer baselength. They form spontaneously during the growth and subsequent continuous capping of GaSb/GaAs quantum dots due to the large strain and substantial As-for-Sb exchange reactions leading to strong Sb segregation.

Thermal stress estimation in relation to spalling of HSC restrained with steel rings at high temperatures

Directory of Open Access Journals (Sweden)

Tanibe T.

2013-09-01

Full Text Available This paper reports on an experimental study regarding the behavior of steel ring-restrained concrete in response to fire exposure. The study was conducted to enable estimation of thermal stress based on steel ring strain in such concrete under the conditions of a RABT 30 heating curve. The specimens used were made from high-strength concrete (Fc: 80 MPa restrained using steel rings with thicknesses of 0.5, 8 and 18 mm.

Overview of the testing activities on ITER sub-scale pre-compression rings

Energy Technology Data Exchange (ETDEWEB)

Rossi, Paolo, E-mail: paolo.rossi@enea.it [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65, 00044 Frascati, Rome (Italy); Capobianchi, Mario; Crescenzi, Fabio; Massimi, Alberto; Mugnaini, Giampiero; Pizzuto, Aldo [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65, 00044 Frascati, Rome (Italy); Knaster, Juan [ITER Organisation, Route de Vinon sur Verdon, 13115, St. Paul lez Durance (France); Rajainmaki, Hannu [FUSION FOR ENERGY, Josep Pla no. 2, Torres Diagonal Litoral Edificio B3, 08019 Barcelona (Spain)

2012-08-15

Highlights: Black-Right-Pointing-Pointer ENEA developed a high strength glass fiber-epoxy composite for ITER pre-compression rings. Black-Right-Pointing-Pointer High UTS values were obtained at RT on linear specimens (2200 MPa) and on scaled ring mock-ups (1550 MPa). Black-Right-Pointing-Pointer Creep tests showed very low creep strain and creep rates. Black-Right-Pointing-Pointer Long term tests showed no significant stress relaxation on the ring mock-ups. - Abstract: After a first R and D and testing activity to develop and characterize by tensile and creep tests a high strength glass fiber-epoxy composite as reference material for the manufacture of ITER pre-compression rings, ENEA designed and manufactured a dedicated testing facility and different sub-scale composite ring mock-ups in order to characterize their mechanical properties. The paper reports the results of the overall testing activities performed during the last years on a total number of eleven sub-scale pre-compression ring mock-ups manufactured by winding S2 glass fibers on a diameter of 1 m (1/5 of the full scale) both by vacuum pressure epoxy impregnation (VPI) and filament wet winding techniques (WW). The first three rings were manufactured by ENEA Frascati thanks to a particular VPI technique; one of them was used as base composite material to manufacture different sets of specimens for shear, compression and non destructive tests (NDT). Then, five other mock-ups were manufactured following ENEA VPI process and three using WW technique by two different industrial companies. The rings were tested in ENEA Frascati in a dedicated hydraulic testing machine consisting of 18 radial actuators working in position control with a total load capability of 1000 tons. The complete testing campaign consisted of six ultimate tensile strength (UTS) tests and four stress relaxation (SR) tests. The tests demonstrated that the composite (S2 glass-epoxy) is a valid and viable solution for the ITER pre

Mechanical improvement of metal reinforcement rings for a finite ring-shaped superconducting bulk

Science.gov (United States)

Huang, Chen-Guang; Zhou, You-He

2018-03-01

As a key technique, reinforcement of type-II superconducting bulks with metal rings can efficiently improve their mechanical properties to enhance the maximum trapped field. In this paper, we study the magnetostrictive and fracture behaviors of a finite superconducting ring bulk reinforced by three typical reinforcing structures composed of metal rings during the magnetizing process by means of the minimization of magnetic energy and the finite element method. After a field-dependent critical current density is adopted, the magnetostriction, pinning-induced stress, and crack tip stress intensity factor are calculated considering the demagnetization effects. The results show that the mechanical properties of the ring bulk are strongly dependent on the reinforcing structure and the material and geometrical parameters of the metal rings. Introducing the metal ring can significantly reduce the hoop stress, and the reduction effect by internal reinforcement is much improved relative to external reinforcement. By comparison, bilateral reinforcement seems to be the best candidate structure. Only when the metal rings have particular Young's modulus and radial thickness will they contribute to improve the mechanical properties the most. In addition, if an edge crack is pre-existing in the ring bulk, the presence of metal rings can effectively avoid crack propagation since it reduces the crack tip stress intensity factor by nearly one order of magnitude.

The properties of Ge quantum rings deposited by pulsed laser deposition.

Science.gov (United States)

Ma, Xiying

2010-07-01

SiGe ring-shape nanostructures have attracted much research interest because of the interesting morphology, mechanical, and electromagnetic properties. In this paper, we present the planar Ge nanorings with well-defined sharp edges self-assembled on Si (100) matrix prepared with pulsed laser deposition (PLD) in the present of Ar gas. The transforming mechanism of the droplets is discussed, which a dynamic deformation model has been developed to simulate the self-transforming process of the droplets. The rings were found to be formed in two steps: from droplets to cones and from cones to rings via an elastic self-deforming process, which were likely to be driven by the lateral strain of Ge/Si layers and the surface tension.

Systematic Search for Rings around Kepler Planet Candidates: Constraints on Ring Size and Occurrence Rate

Science.gov (United States)

Aizawa, Masataka; Masuda, Kento; Kawahara, Hajime; Suto, Yasushi

2018-05-01

We perform a systematic search for rings around 168 Kepler planet candidates with sufficient signal-to-noise ratios that are selected from all of the short-cadence data. We fit ringed and ringless models to their light curves and compare the fitting results to search for the signatures of planetary rings. First, we identify 29 tentative systems, for which the ringed models exhibit statistically significant improvement over the ringless models. The light curves of those systems are individually examined, but we are not able to identify any candidate that indicates evidence for rings. In turn, we find several mechanisms of false positives that would produce ringlike signals, and the null detection enables us to place upper limits on the size of the rings. Furthermore, assuming the tidal alignment between axes of the planetary rings and orbits, we conclude that the occurrence rate of rings larger than twice the planetary radius is less than 15%. Even though the majority of our targets are short-period planets, our null detection provides statistical and quantitative constraints on largely uncertain theoretical models of the origin, formation, and evolution of planetary rings.

Evaluation of ring tensile test results

International Nuclear Information System (INIS)

Chatterjee, S.; Anantharaman, S.; Balakrishnan, K.S.; Sivaramakrish, K.S.

1990-01-01

Ring specimens of 5-mm width cut from Zircaloy-2 cladding of reactor operated fuel elements that had experienced 5000 to 15,000 MWD/T of fuel burnup were subjected to ring tensile testing. The true stress-true strain data points up to the onset of necking from the individual load-elongation curves of these specimens were used as input data in Voce's equation. The results reveal that the uniform elongation (UE) values generated using Voce's equation were within (UE-2)% of the experimental percent uniform elongation (UE%). The corresponding ultimate tensile strength values were within ±1%. The uncertainty inherently associated in the determination of gauge length introduces extraneous deformation in the rings tested. Previous results had shown that a 14% increase in cladding diameter caused the gauge length to increase by 40%. To simulate the contribution of extraneous deformation due to an increase in cladding diameter, an analysis of the variation of the tensile parameters (uniform elongation and ultimate tensile strength) due to increase in the gauge length in the range of 10 to 40% was carried out. The results are discussed

Ring Theory

CERN Document Server

Jara, Pascual; Torrecillas, Blas

1988-01-01

The papers in this proceedings volume are selected research papers in different areas of ring theory, including graded rings, differential operator rings, K-theory of noetherian rings, torsion theory, regular rings, cohomology of algebras, local cohomology of noncommutative rings. The book will be important for mathematicians active in research in ring theory.

Comparison of ring compression testing to three point bend testing for unirradiated ZIRLO cladding

Energy Technology Data Exchange (ETDEWEB)

None, None

2015-04-01

Safe shipment and storage of nuclear reactor discharged fuel requires an understanding of how the fuel may perform under the various conditions that can be encountered. One specific focus of concern is performance during a shipment drop accident. Tests at Savannah River National Laboratory (SRNL) are being performed to characterize the properties of fuel clad relative to a mechanical accident condition such as a container drop. Unirradiated ZIRLO tubing samples have been charged with a range of hydride levels to simulate actual fuel rod levels. Samples of the hydrogen charged tubes were exposed to a radial hydride growth treatment (RHGT) consisting of heating to 400°C, applying initial hoop stresses of 90 to 170 MPa with controlled cooling and producing hydride precipitates. Initial samples have been tested using both a) ring compression test (RCT) which is shown to be sensitive to radial hydride and b) three-point bend tests which are less sensitive to radial hydride effects. Hydrides are generated in Zirconium based fuel cladding as a result of coolant (water) oxidation of the clad, hydrogen release, and a portion of the released (nascent) hydrogen absorbed into the clad and eventually exceeding the hydrogen solubility limit. The orientation of the hydrides relative to the subsequent normal and accident strains has a significant impact on the failure susceptability. In this study the impacts of stress, temperature and hydrogen levels are evaluated in reference to the propensity for hydride reorientation from the circumferential to the radial orientation. In addition the effects of radial hydrides on the Quasi Ductile Brittle Transition Temperature (DBTT) were measured. The results suggest that a) the severity of the radial hydride impact is related to the hydrogen level-peak temperature combination (for example at a peak drying temperature of 400°C; 800 PPM hydrogen has less of an impact/ less radial hydride fraction than 200 PPM hydrogen for the same thermal

Analysis of ring enhancement in the cranial computed tomography

Energy Technology Data Exchange (ETDEWEB)

Huh, Seung Jae; Chung, Yong In; Chang, Kee Hyun [College of Medicine, Seoul National University, Seoul (Korea, Republic of)

1980-12-15

A total of 83 cases with ring enhancement in the cranial computed tomography were radiologically analyzed to determine the specific CT findings of the primary and metastatic brain tumor, inflammatory disease, resolving hematoma, and cerebral infarction. The brief results are as follows. Glioblastoma multiform show a characteristic thick or thin irregular ring enhancement with significant mass effect and surrounding edema. Most of the metastatic tumors also show irregular thick or thin walled ring enhancement with significant surrounding edema. Tumoral hemorrhage was observed in the metastatic melanoma, breast cancer, and lung cancer. The brain abscess usually show characteristic thin regular and smooth ring enhancement with moderate peripheral edema. The parasitic cysts also show thin regular ring enhancement with different degree of surrounding edema. Ring enhancement in resolving hematomas and cerebral infarctions usually occurs about 10-30 days after the onset of symptoms, which shows thin and regular ring pattern without significant surrounding edema.

Analysis of ring enhancement in the cranial computed tomography

International Nuclear Information System (INIS)

Huh, Seung Jae; Chung, Yong In; Chang, Kee Hyun

1980-01-01

A total of 83 cases with ring enhancement in the cranial computed tomography were radiologically analyzed to determine the specific CT findings of the primary and metastatic brain tumor, inflammatory disease, resolving hematoma, and cerebral infarction. The brief results are as follows. Glioblastoma multiform show a characteristic thick or thin irregular ring enhancement with significant mass effect and surrounding edema. Most of the metastatic tumors also show irregular thick or thin walled ring enhancement with significant surrounding edema. Tumoral hemorrhage was observed in the metastatic melanoma, breast cancer, and lung cancer. The brain abscess usually show characteristic thin regular and smooth ring enhancement with moderate peripheral edema. The parasitic cysts also show thin regular ring enhancement with different degree of surrounding edema. Ring enhancement in resolving hematomas and cerebral infarctions usually occurs about 10-30 days after the onset of symptoms, which shows thin and regular ring pattern without significant surrounding edema

Improved thermal stability and hole mobilities in a strained-Si/strained-Si1-yGe y/strained-Si heterostructure grown on a relaxed Si1-xGe x buffer

International Nuclear Information System (INIS)

Gupta, Saurabh; Lee, Minjoo L.; Isaacson, David M.; Fitzgerald, Eugene A.

2005-01-01

A dual channel heterostructure consisting of strained-Si/strained-Si 1-y Ge y on relaxed Si 1-x Ge x (y > x), provides a platform for fabricating metal-oxide-semiconductor field-effect transistors (MOSFETs) with high hole mobilities (μ eff ) which depend directly on Ge concentration and strain in the strained-Si 1-y Ge y layer. Ge out-diffuses from the strained-Si 1-y Ge y layer into relaxed Si 1-x Ge x during high temperature processing, reducing peak Ge concentration and strain in the strained-Si 1-y Ge y layer and degrades hole μ eff in these dual channel heterostructures. A heterostructure consisting of strained-Si/strained-Si 1-y Ge y /strained-Si, referred to as a trilayer heterostructure, grown on relaxed Si 1-x Ge x has much reduced Ge out-flux from the strained-Si 1-y Ge y layer and retains higher μ eff after thermal processing. Improved hole μ eff over similar dual channel heterostructures is also observed in this heterostructure. This could be a result of preventing the hole wavefunction tunneling into the low μ eff relaxed Si 1-x Ge x layer due to the additional valence band offset provided by the underlying strained-Si layer. A diffusion coefficient has been formulated and implemented in a finite difference scheme for predicting the thermal budget of the strained SiGe heterostructures. It shows that the trilayer heterostructures have superior thermal budgets at higher Ge concentrations. Ring-shaped MOSFETs were fabricated on both platforms and subjected to various processing temperatures in order to compare the extent of μ eff reduction with thermal budget. Hole μ eff enhancements are retained to a much higher extent in a trilayer heterostructure after high temperature processing as compared to a dual channel heterostructure. The improved thermal stability and hole μ eff of a trilayer heterostructure makes it an ideal platform for fabricating high μ eff MOSFETs that can be processed over higher temperatures without significant losses in hole �

Significant contribution of stacking faults to the strain hardening behavior of Cu-15%Al alloy with different grain sizes.

Science.gov (United States)

Tian, Y Z; Zhao, L J; Chen, S; Shibata, A; Zhang, Z F; Tsuji, N

2015-11-19

It is commonly accepted that twinning can induce an increase of strain-hardening rate during the tensile process of face-centered cubic (FCC) metals and alloys with low stacking fault energy (SFE). In this study, we explored the grain size effect on the strain-hardening behavior of a Cu-15 at.%Al alloy with low SFE. Instead of twinning, we detected a significant contribution of stacking faults (SFs) irrespective of the grain size even in the initial stage of tensile process. In contrast, twinning was more sensitive to the grain size, and the onset of deformation twins might be postponed to a higher strain with increasing the grain size. In the Cu-15 at.%Al alloy with a mean grain size of 47 μm, there was a stage where the strain-hardening rate increases with strain, and this was mainly induced by the SFs instead of twinning. Thus in parallel with the TWIP effect, we proposed that SFs also contribute significantly to the plasticity of FCC alloys with low SFE.

Dynamic electrical characteristics of low-power ring oscillators constructed with inorganic nanoparticles on flexible plastics.

Science.gov (United States)

Yun, Junggwon; Cho, Kyoungah; Kim, Sangsig

2012-11-01

In this study, we demonstrate for the first time the low-power and stable performance of a ring oscillator constructed on a flexible plastic with solution-processable inorganic nanoparticles (NPs). Our flexible ring oscillator is composed of three inverters based on n- and p-type inorganic NP thin-film transistors. Each of the component inverters exhibits a gain of ∼80 at a voltage of 5 V. For the ring oscillator, the sine waves are generated with a frequency of up to 12 kHz. The waveforms are undistorted under strained conditions and maintained even after 5000 bending cycles. The frequency and waveform of the output waves obtained from our flexible ring oscillator are analyzed and discussed in detail.

ASSOCIATIVE RINGS SOLVED AS LIE RINGS

Directory of Open Access Journals (Sweden)

M. B. Smirnov

2011-01-01

Full Text Available The paper has proved that an associative ring which is solvable of a n- class as a Lie ring has a nilpotent ideal of the nilpotent class not more than 3×10n–2  and a corresponding quotient ring satisfies an identity [[x1, x2, [x3, x4

Experimental buckling investigation of ring-stiffened cyclindrical shells under unsymmetrical axial loads

International Nuclear Information System (INIS)

Baker, W.E.; Bennett, J.G.; Babcock, C.D.

1983-01-01

Six steel shells having nuclear containment-like features were fabricated and loaded to failure with an offset axial load. The shells of R/t = 500 buckled plastically. Four of the shells had reinforced circular cutouts. These penetrations were sized to cut no ring-stiffener, a single, two- or three-ring stiffeners. Reinforcing and framing around the penetrations were based upon the area-replacement rule of the applicable portion of the American Society for Mechanical Engineers (ASME) Boiler and Pressure Vessel Code and were of a design to simulate actual practice for nuclear steel containments. Prior to testing, imperfections were measured and strain gages were applied to determine information on load distribution at the ends of the cylinder and strain fields at areas likely to buckle. Buckling loads were determined for an axial load applied with an eccentricity of R/2 where R is the cylinder radius

Ground Movement in SSRL Ring

International Nuclear Information System (INIS)

Sunikumar, Nikita

2011-01-01

Users of the Stanford Synchrotron Radiation Lightsource (SSRL) are being affected by diurnal motion of the synchrotron's storage ring, which undergoes structural changes due to outdoor temperature fluctuations. In order to minimize the effects of diurnal temperature fluctuations, especially on the vertical motion of the ring floor, scientists at SSRL tried three approaches: painting the storage ring white, covering the asphalt in the middle of the ring with highly reflective Mylar and installing Mylar on a portion of the ring roof and walls. Vertical motion in the storage ring is measured by a Hydrostatic Leveling System (HLS), which calculates the relative height of water in a pipe that extends around the ring. The 24-hr amplitude of the floor motion was determined using spectral analysis of HLS data, and the ratio of this amplitude before and after each experiment was used to quantitatively determine the efficacy of each approach. The results of this analysis showed that the Mylar did not have any significant effect on floor motion, although the whitewash project did yield a reduction in overall HLS variation of 15 percent. However, further analysis showed that the reduction can largely be attributed to a few local changes rather than an overall reduction in floor motion around the ring. Future work will consist of identifying and selectively insulating these local regions in order to find the driving force behind diurnal floor motion in the storage ring.

Cooling rings for TeV colliders

International Nuclear Information System (INIS)

Palmer, R.B.

1985-02-01

Consideration is given to quantum fluctuations, intra beam scattering, cooling rates, and ring acceptance in order to see if one can obtain a normalized emittance of 10 -8 in any plausible cooling ring. It is concluded that only a small gain is obtained by varying the partition functions, but a very significant gain is made by using higher bending fields. The ring is found to get bigger if the magnet apertures are increased. The ring diameter is found to increase if the momentum spread of the beam is reduced. It is shown that the power can be reduced by allowing a high beamstrahlung energy loss resulting in higher current in the cooling ring. Parameters are also given for a 10 -7 m radian emittance case

Biotransformation of Bicyclic Halolactones with a Methyl Group in the Cyclohexane Ring into Hydroxylactones and Their Biological Activity

Directory of Open Access Journals (Sweden)

Katarzyna Wińska

2016-10-01

Full Text Available The aim of this study was the chemical synthesis of a series of halo- and unsaturated lactones, as well as their microbial transformation products. Finally some of their biological activities were assessed. Three bicyclic halolactones with a methyl group in the cyclohexane ring were obtained from the corresponding γ,δ-unsaturated ester during a two-step synthesis. These lactones were subjected to screening biotransformation using twenty two fungal strains. These strains were tested on their ability to transform halolactones into new hydroxylactones. Among the six strains able to catalyze hydrolytic dehalogenation, only two (Fusarium equiseti, AM22 and Yarrowia lipolytica, AM71 gave a product in a high yield. Moreover, one strain (Penicillium wermiculatum, AM30 introduced the hydroxy group on the cyclohexane ring without removing the halogen atom. The biological activity of five of the obtained lactones was tested. Some of these compounds exhibited growth inhibition against bacteria, yeasts and fungi and deterrent activity against peach-potato aphid.

Investigating the Activity Spectrum for Ring-Substituted 8-Hydroxyquinolines

Directory of Open Access Journals (Sweden)

Aidan Coffey

2010-01-01

Full Text Available In this study, a series of fourteen ring-substituted 8-hydroxyquinoline derivatives were prepared. The synthesis procedures are presented. The compounds were analyzed using RP-HPLC to determine lipophilicity. They were tested for their activity related to inhibition of photosynthetic electron transport (PET in spinach (Spinacia oleracea L. chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four mycobacterial strains and against eight fungal strains. Several compounds showed biological activity comparable with or higher than the standards isoniazid or fluconazole. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds are discussed.

Ring ductility of irradiated Inconel 706 and Nimonic PE16

International Nuclear Information System (INIS)

Huang, F.H.; Fish, R.L.

1984-01-01

The tensile ductility of fast neutron-irradiated, precipitation-hardened alloys Inconel 706 and Nimonic PE16 has been observed to be very low for certain test conditions. Explanations for the low ductility behavior have been sought by examination of broken tensile specimens with microscopy and other similar techniques. A ring compression test provides a method of evaluating the ductility of irradiated cladding specimens. Unlike the conventional uniaxial tensile testing in which the tensile specimen is deformed uniformly, the ring specimen is subjected to localized bending where the crack is initiated. The ductility can be estimated through an analysis of the bending of a ring in terms of strain hardening. Ring sections from irradiated, solution-treated Inconel 706 and Nimonic PE16 were compressed in the diametral direction to provide load-deflection records over a wide range of irradiation and test temperatures. Results showed that ductility in both alloys decreased with increasing test temperatures. The poorest ductility was exhibited at different irradiation temperatures in the two alloys - near 550 0 C for PE16 and 460 to 520 0 C for Inconel 706. The ring ductility data indicate that the grain boundary strength is a major factor in controlling the ductility of the PE16 alloy

Optical fiber strain sensor using fiber resonator based on frequency comb Vernier spectroscopy

DEFF Research Database (Denmark)

Zhang, Liang; Lu, Ping; Chen, Li

2012-01-01

A novel (to our best knowledge) optical fiber strain sensor using a fiber ring resonator based on frequency comb Vernier spectroscopy is proposed and demonstrated. A passively mode-locked optical fiber laser is employed to generate a phased-locked frequency comb. Strain applied to the optical fib...

Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

Science.gov (United States)

Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

2010-10-01

Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

PREFACE: Special section on vortex rings Special section on vortex rings

Science.gov (United States)

Fukumoto, Yasuhide

2009-10-01

This special section of Fluid Dynamics Research includes five articles on vortex rings in both classical and quantum fluids. The leading scientists of the field describe the trends in and the state-of-the-art development of experiments, theories and numerical simulations of vortex rings. The year 2008 was the 150th anniversary of 'vortex motion' since Hermann von Helmholtz opened up this field. In 1858, Helmholtz published a paper in Crelle's Journal which put forward the concept of 'vorticity' and made the first analysis of vortex motion. Fluid mechanics before that was limited to irrotational motion. In the absence of vorticity, the motion of an incompressible homogeneous fluid is virtually equivalent to a rigid-body motion in the sense that the fluid motion is determined once the boundary configuration is specified. Helmholtz proved, among other things, that, without viscosity, a vortex line is frozen into the fluid. This Helmholtz's law immediately implies the preservation of knots and links of vortex lines and its implication is enormous. One of the major trends of fluid mechanics since the latter half of the 20th century is to clarify the topological meaning of Helmholtz's law and to exploit it to develop theoretical and numerical methods to find the solutions of the Euler equations and to develop experimental techniques to gain an insight into fluid motion. Vortex rings are prominent coherent structures in a variety of fluid motions from the microscopic scale, through human and mesoscale to astrophysical scales, and have attracted people's interest. The late professor Philip G Saffman (1981) emphasized the significance of studies on vortex rings. One particular motion exemplifies the whole range of problems of vortex motion and is also a commonly known phenomenon, namely the vortex ring or smoke ring. Vortex rings are easily produced by dropping drops of one liquid into another, or by puffing fluid out of a hole, or by exhaling smoke if one has the skill

Evolutionarily conserved sites in yeast tropomyosin function in cell polarity, transport and contractile ring formation

Directory of Open Access Journals (Sweden)

Susanne Cranz-Mileva

2015-08-01

Full Text Available Tropomyosin is a coiled-coil protein that binds and regulates actin filaments. The tropomyosin gene in Schizosaccharomyces pombe, cdc8, is required for formation of actin cables, contractile rings, and polar localization of actin patches. The roles of conserved residues were investigated in gene replacement mutants. The work validates an evolution-based approach to identify tropomyosin functions in living cells and sites of potential interactions with other proteins. A cdc8 mutant with near-normal actin affinity affects patch polarization and vacuole fusion, possibly by affecting Myo52p, a class V myosin, function. The presence of labile residual cell attachments suggests a delay in completion of cell division and redistribution of cell patches following cytokinesis. Another mutant with a mild phenotype is synthetic negative with GFP-fimbrin, inferring involvement of the mutated tropomyosin sites in interaction between the two proteins. Proteins that assemble in the contractile ring region before actin do so in a mutant cdc8 strain that cannot assemble condensed actin rings, yet some cells can divide. Of general significance, LifeAct-GFP negatively affects the actin cytoskeleton, indicating caution in its use as a biomarker for actin filaments.

Parametric instability of spinning elastic rings excited by fluctuating space-fixed stiffnesses

Science.gov (United States)

Liu, Chunguang; Cooley, Christopher G.; Parker, Robert G.

2017-07-01

This study investigates the vibration of rotating elastic rings that are dynamically excited by an arbitrary number of space-fixed discrete stiffnesses with periodically fluctuating stiffnesses. The rotating, elastic ring is modeled using thin-ring theory with radial and tangential deformations. Primary and combination instability regions are determined in closed-form using the method of multiple scales. The ratio of peak-to-peak fluctuation to average discrete stiffness is used as the perturbation parameter, so the resulting perturbation analysis is not limited to small mean values of discrete stiffnesses. The natural frequencies and vibration modes are determined by discretizing the governing equations using Galerkin's method. Results are demonstrated for compliant gear applications. The perturbation results are validated by direct numerical integration of the equations of motion and Floquet theory. The bandwidths of the instability regions correlate with the fractional strain energy stored in the discrete stiffnesses. For rings with multiple discrete stiffnesses, the phase differences between them can eliminate large amplitude response under certain conditions.

Apple ring rot-responsive putative microRNAs revealed by high-throughput sequencing in Malus × domestica Borkh.

Science.gov (United States)

Yu, Xin-Yi; Du, Bei-Bei; Gao, Zhi-Hong; Zhang, Shi-Jie; Tu, Xu-Tong; Chen, Xiao-Yun; Zhang, Zhen; Qu, Shen-Chun

2014-08-01

MicroRNAs (miRNAs) are small non-coding RNAs, which silence target mRNA via cleavage or translational inhibition to function in regulating gene expression. MiRNAs act as important regulators of plant development and stress response. For understanding the role of miRNAs responsive to apple ring rot stress, we identified disease-responsive miRNAs using high-throughput sequencing in Malus × domestica Borkh.. Four small RNA libraries were constructed from two control strains in M. domestica, crabapple (CKHu) and Fuji Naga-fu No. 6 (CKFu), and two disease stress strains, crabapple (DSHu) and Fuji Naga-fu No. 6 (DSFu). A total of 59 miRNA families were identified and five miRNAs might be responsive to apple ring rot infection and validated via qRT-PCR. Furthermore, we predicted 76 target genes which were regulated by conserved miRNAs potentially. Our study demonstrated that miRNAs was responsive to apple ring rot infection and may have important implications on apple disease resistance.

Significance of Strain in Formulation in Theory of Solid Mechanics

Science.gov (United States)

Patnaik, Surya N.; Coroneos, Rula M.; Hopkins, Dale A.

2003-01-01

The basic theory of solid mechanics was deemed complete circa 1860 when St. Venant provided the strain formulation or the field compatibility condition. The strain formulation was incomplete. The missing portion has been formulated and identified as the boundary compatibility condition (BCC). The BCC, derived through a variational formulation, has been verified through integral theorem and solution of problems. The BCC, unlike the field counterpart, do not trivialize when expressed in displacements. Navier s method and the stiffness formulation have to account for the extra conditions especially at the inter-element boundaries in a finite element model. Completion of the strain formulation has led to the revival of the direct force calculation methods: the Integrated Force Method (IFM) and its dual (IFMD) for finite element analysis, and the completed Beltrami-Michell formulation (CBMF) in elasticity. The benefits from the new methods in elasticity, in finite element analysis, and in design optimization are discussed. Existing solutions and computer codes may have to be adjusted for the compliance of the new conditions. Complacency because the discipline is over a century old and computer codes have been developed for half a century can lead to stagnation of the discipline.

Valence band structures of InAs/GaAs quantum rings using the Fourier transform method

International Nuclear Information System (INIS)

Jia Boyong; Yu Zhongyuan; Liu Yumin

2009-01-01

The valence band structures of strained InAs/GaAs quantum rings are calculated, with the four-band k · p model, in the framework of effective-mass envelope function theory. When determining the Hamiltonian matrix elements, we develop the Fourier transform method instead of the widely used analytical integral method. Using Fourier transform, we have investigated the energy levels as functions of the geometrical parameters of the rings and compared our results with those obtained by the analytical integral method. The results show that the energy levels in the quantum rings change dramatically with the inner radius, outer radius, average radius, width, height of the ring and the distance between two adjacent rings. Our method can be adopted in low-dimensional structures with arbitrary shape. Our results are consistent with those in the literature and should be helpful for studying and fabricating optoelectronic devices

Conformational locking by design: relating strain energy with luminescence and stability in rigid metal-organic frameworks.

Science.gov (United States)

Shustova, Natalia B; Cozzolino, Anthony F; Dincă, Mircea

2012-12-05

Minimization of the torsional barrier for phenyl ring flipping in a metal-organic framework (MOF) based on the new ethynyl-extended octacarboxylate ligand H(8)TDPEPE leads to a fluorescent material with a near-dark state. Immobilization of the ligand in the rigid structure also unexpectedly causes significant strain. We used DFT calculations to estimate the ligand strain energies in our and all other topologically related materials and correlated these with empirical structural descriptors to derive general rules for trapping molecules in high-energy conformations within MOFs. These studies portend possible applications of MOFs for studying fundamental concepts related to conformational locking and its effects on molecular reactivity and chromophore photophysics.

Analytical stiffness matrices with Green-Lagrange strain measure

DEFF Research Database (Denmark)

Pedersen, Pauli

2005-01-01

Separating the dependence on material and stress/strain state from the dependence on initial geometry, we obtain analytical secant and tangent stiffness matrices. For the case of a linear displacement triangle with uniform thickness and uniform constitutive behaviour closed-form results are listed...... a solution based on Green-Lagrange strain measure. The approach is especially useful in design optimization, because analytical sensitivity analysis then can be performed. The case of a three node triangular ring element for axisymmetric analysis involves small modifications and extension to four node...

Fengycin produced by Bacillus subtilis 9407 plays a major role in the biocontrol of apple ring rot disease.

Science.gov (United States)

Fan, Haiyan; Ru, Jinjiang; Zhang, Yuanyuan; Wang, Qi; Li, Yan

2017-06-01

Apple ring rot, caused by Botryosphaeria dothidea, is a serious apple disease in China. Bacillus subtilis 9407 was isolated from healthy apples and showed strong antifungal activity against B. dothidea. To identify the primary antifungal compound of B. subtilis 9407 and determine its role in controlling apple ring rot, a transposon mutant library was constructed using TnYLB-1, and a mutant completely defective in antifungal activity was obtained. The gene inactivated in the antifungal activity mutant had 98.5% similarity to ppsB in B. subtilis subsp. subtilis str. 168, which encodes one of the five synthetases responsible for synthesizing fengycin. A markerless ppsB deletion mutant was constructed. Compared with the wild-type strain, lipopeptide crude extracts from ΔppsB showed almost no inhibition of B. dothidea mycelial growth. Furthermore, fengycin-like lipopeptides (retention factor 0.1-0.2) that exhibited antifungal activity against B. dothidea were observed in the wild-type strain by thin-layer chromatography (TLC)-bioautography analysis, but not in ΔppsB. Semipreparative reverse-phase high performance liquid chromatography (RP-HPLC) detection revealed that ΔppsB lost the ability to synthesize fengycin. These results suggest that ppsB is responsible for synthesizing fengycin and that fengycin is the major antifungal compound produced by B. subtilis 9407 against B. dothidea. Moreover, a biocontrol assay showed that the control efficacy of ΔppsB was reduced by half compared with the wild-type strain, indicating that fengycin plays a major role in controlling apple ring rot disease. This is the first report on the use of a B. subtilis strain as a potential biological control agent to control apple ring rot disease by the production of fengycin. Copyright © 2017 Elsevier GmbH. All rights reserved.

Black rings

International Nuclear Information System (INIS)

Emparan, Roberto; Reall, Harvey S

2006-01-01

A black ring is a five-dimensional black hole with an event horizon of topology S 1 x S 2 . We provide an introduction to the description of black rings in general relativity and string theory. Novel aspects of the presentation include a new approach to constructing black ring coordinates and a critical review of black ring microscopics. (topical review)

Seco-B-Ring Steroidal Dienynes with Aromatic D Ring: Design, Synthesis and Biological Evaluation

Directory of Open Access Journals (Sweden)

Marcin Szybinski

2017-10-01

Full Text Available Continuing our structure-activity studies on the vitamin D analogs with the altered intercyclic seco-B-ring fragment, we designed compounds possessing dienyne system conjugated with the benzene D ring. Analysis of the literature data and the docking experiments seemed to indicate that the target compounds could mimic the ligands with a good affinity to the vitamin D receptor (VDR. Multi-step synthesis of the C/D-ring building block of the tetralone structure was achieved and its enol triflate was coupled with the known A-ring fragments, possessing conjugated enyne moiety, using Sonogashira protocol. The structures of the final products were confirmed by NMR, UV and mass spectroscopy. Their binding affinities for the full-length human VDR were determined and it was established that compound substituted at C-2 with exomethylene group showed significant binding to the receptor. This analog was also able to induce monocytic differentiation of HL-60 cells.

Saturn’s ring temperatures at equinox

Science.gov (United States)

Spilker, Linda J.; Ferrari, C.; Morishima, R.

2013-10-01

Modeling the thermal emission of Saturn's rings is challenging due to the numerous heating sources as well as the structural properties of the disk and of the particles that are closely related. At equinox, however, the main rings are externally heated by Saturn alone and the problem is somewhat simplified. We test the abilities of our current models to reproduce the temperatures observed with the Cassini CIRS instrument around equinox in August 2009. A simple semi-analytic model which includes mutual shadowing effects can mostly explain the radial profile of the equinox ring temperatures, except the model predicts lower temperatures than those observed for the A ring. The temperature variation at a given saturnocentric radius is primarily caused by observational geometry variations relative to Saturn. The observed temperature increases with decreasing Saturn-ring-observer angle. In addition, we found evidence that the leading hemispheres of particles are warmer than the trailing hemispheres at least for the C ring and probably for the A and B rings as well. This is explained if some fraction of particles has spin rates lower than the synchronous rotation rate as predicted by N-body simulations. The spin model for a monolayer ring (Ferrari, C., Leyrat, C., 2006, Astron. Astrophys. 447, 745-760) can fit the temperature variations with spacecraft longitude observed in the C ring with currently known thermal properties and a mixing of slow and fast rotators. The multilayer model (Morishima, R., Salo, H., Ohtsuki, K., 2009, Icarus 201, 634-654) can reproduce the temperatures of the B and C rings but gives A ring temperatures that are significantly lower than those observed as does the simple semi-analytic model. More advanced models which take into account self-gravity wakes may explain the A ring temperature behavior.

Experimental buckling investigation of ring-stiffened cylindrical shells under unsymmetrical axial loads

International Nuclear Information System (INIS)

Baker, W.E.; Babock, C.D.; Bennett, J.G.

1983-01-01

Six steel shells having nuclear containment-like features were fabricated and loaded to failure with an offset axial load. The shells of R/t = 500 buckled plastically. Four of the shells had reinforced circular cutouts. These penetrations were sized to cut no ring-stiffener, a single, two- or three-ring stiffeners. Reinforcing and framing around the penetrations were based upon the area-replacement rule of the applicable portion of the American Society for Mechanical Engineers (ASME) Boiler and Pressure Vessel Code and were of a design to stimulate actual practice for nuclear steel containments. Prior to testing, imperfections were measured and strain gages were applied to determine information on load distribution at the ends of the cylinder and strain fields at areas likely to buckle. Buckling loads were determined for an axial load applied with an eccentricity of R/2 where R is the cylinder radius. The results showed that the buckling load and mode for the shell having a penetration that did not cut a ring stiffener were essentially the same as those for the unpenetrated shell. The buckling loads for the penetrated shells in which stiffeners were interrupted were less than that for the unpenetrated shells. Results of all tests are compared to numerical solutions carried out using a nonlinear collapse analysis and to the predictions of ASME Code Case N-284

A numerical study of viscous vortex rings using a spectral method

Science.gov (United States)

Stanaway, S. K.; Cantwell, B. J.; Spalart, Philippe R.

1988-01-01

Viscous, axisymmetric vortex rings are investigated numerically by solving the incompressible Navier-Stokes equations using a spectral method designed for this type of flow. The results presented are axisymmetric, but the method is developed to be naturally extended to three dimensions. The spectral method relies on divergence-free basis functions. The basis functions are formed in spherical coordinates using Vector Spherical Harmonics in the angular directions, and Jacobi polynomials together with a mapping in the radial direction. Simulations are performed of a single ring over a wide range of Reynolds numbers (Re approximately equal gamma/nu), 0.001 less than or equal to 1000, and of two interacting rings. At large times, regardless of the early history of the vortex ring, it is observed that the flow approaches a Stokes solution that depends only on the total hydrodynamic impulse, which is conserved for all time. At small times, from an infinitely thin ring, the propagation speeds of vortex rings of varying Re are computed and comparisons are made with the asymptotic theory by Saffman. The results are in agreement with the theory; furthermore, the error is found to be smaller than Saffman's own estimate by a factor square root ((nu x t)/R squared) (at least for Re=0). The error also decreases with increasing Re at fixed core-to-ring radius ratio, and appears to be independent of Re as Re approaches infinity). Following a single ring, with Re=500, the vorticity contours indicate shedding of vorticity into the wake and a settling of an initially circular core to a more elliptical shape, similar to Norbury's steady inviscid vortices. Finally, we consider the case of leapfrogging vortex rings with Re=1000. The results show severe straining of the inner vortex core in the first pass and merging of the two cores during the second pass.

Variations in Ring Particle Cooling across Saturn's Rings with Cassini CIRS

Science.gov (United States)

Brooks, S. M.; Spilker, L. J.; Pilorz, S.; Edgington, S. G.; Déau, E.; Altobelli, N.

2010-12-01

Cassini's Composite Infrared Spectrometer has recorded over two million of spectra of Saturn's rings in the far infrared since arriving at Saturn in 2004. CIRS records far infrared radiation between 10 and 600 cm-1 ( 16.7 and 1000 μ {m} ) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn’s rings peaks in this wavelength range. Ring temperatures can be inferred from FP1 data. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and rapidly changing temperatures are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid particles can be expected to have higher thermal inertias. Ferrari et al. (2005) fit thermal inertia values of 5218 {Jm)-2 {K}-1 {s}-1/2 to their B ring data and 6412 {Jm)-2 {K}-1 {s}-1/2 to their C ring data. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The rings’ thermal budget is dominated by its absorption of solar radiation. As a result, ring particles abruptly cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

Thermoset polymers via ring opening metathesis polymerization of functionalized oils

Science.gov (United States)

Larock, Richard C; Henna, Phillip H; Kessier, Michael R

2012-11-27

The invention provides a method for producing a thermosetting resin from renewable oils, the method comprising supplying renewable oil molecules containing strained ring alkene moieties; reacting the alkene moieties with cyclic alkenes to create a polymer; and repeating the above two steps until the resin having desired characteristics are obtained. Also provided is a thermoset resin comprising functionalized renewable oil polymerized with a co-monomer.

Local, atomic-level elastic strain measurements of metallic glass thin films by electron diffraction

Energy Technology Data Exchange (ETDEWEB)

Ebner, C. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Sarkar, R. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rajagopalan, J. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Department of Mechanical and Aerospace Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rentenberger, C., E-mail: christian.rentenberger@univie.ac.at [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria)

2016-06-15

A novel technique is used to measure the atomic-level elastic strain tensor of amorphous materials by tracking geometric changes of the first diffuse ring of selected area electron diffraction patterns (SAD). An automatic procedure, which includes locating the centre and fitting an ellipse to the diffuse ring with sub-pixel precision is developed for extracting the 2-dimensional strain tensor from the SAD patterns. Using this technique, atomic-level principal strains from micrometre-sized regions of freestanding amorphous Ti{sub 0.45}Al{sub 0.55} thin films were measured during in-situ TEM tensile deformation. The thin films were deformed using MEMS based testing stages that allow simultaneous measurement of the macroscopic stress and strain. The calculated atomic-level principal strains show a linear dependence on the applied stress, and good correspondence with the measured macroscopic strains. The calculated Poisson’s ratio of 0.23 is reasonable for brittle metallic glasses. The technique yields a strain accuracy of about 1×10{sup −4} and shows the potential to obtain localized strain profiles/maps of amorphous thin film samples. - Highlights: • A TEM method to measure elastic strain in metallic glass films is proposed. • Method is based on tracking geometric changes in TEM diffraction patterns. • An automatic procedure is developed for extracting the local strain tensor. • Atomic-level strain in amorphous TiAl film was analysed during in-situ deformation. • Capability of the method to obtain micrometer scale strain profiles/maps is shown.

CMB lensing and giant rings

Energy Technology Data Exchange (ETDEWEB)

Rathaus, Ben; Itzhaki, Nissan, E-mail: nitzhaki@post.tau.ac.il, E-mail: ben.rathaus@gmail.com [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel-Aviv University, Ramat-Aviv, 69978 (Israel)

2012-05-01

We study the CMB lensing signature of a pre-inationary particle (PIP), assuming it is responsible for the giant rings anomaly that was found recently in the WMAP data. Simulating Planck-like data we find that generically the CMB lensing signal to noise ratio associated with such a PIP is quite small and it would be difficult to cross correlate the temperature giant rings with the CMB lensing signal. However, if the pre-inationary particle is also responsible for the bulk flow measured from the local large scale structure, which happens to point roughly at the same direction as the giant rings, then the CMB lensing signal to noise ratio is fairly significant.

Alternative loop rings

CERN Document Server

Goodaire, EG; Polcino Milies, C

1996-01-01

For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

Primitivity and weak distributivity in near rings and matrix near rings

International Nuclear Information System (INIS)

Abbasi, S.J.

1993-08-01

This paper shows the structure of matrix near ring constructed over a weakly distributive and primative near ring. It is proved that a weakly distributive primitive near ring is a ring and the matrix near rings constructed over it is also a bag. (author). 14 refs

[Comparative study of aromatic ring meta-cleavage enzymes in Pseudomonas strains with plasmid and chromosomal genetic control of the catabolism of biphenyl and m-toluate].

Science.gov (United States)

Selifonov, S A; Starozoĭtov, I I

1990-12-01

It was shown that two different enzymes of aromatic ring oxidative meta-cleavage (2,3-dihydroxybiphenyl-1,2-dioxygenase), DBO and catechol-2,3-dioxygenase, C230) function in Pseudomonas strains with a plasmid and chromosomal genetic control of biphenyl and toluate catabolism. A comparative analysis of DBO's and C230's expressed by the pBS241 biphenyl degradative plasmid in P. putida BS893, pBS311 in P. putida U83, chromosomal genes in P. putida BF and C230 from P. putida PaW160 (pWWO) was carried out. It was found that the DBO's of all strains under study are highly specialized enzymes in respect of 2,3-dihydroxybiphenyl cleavage and are also able to cleave 3-methyl-catechol and catechol (but not 4-methylcatechol) at low rates. In contrast with DBO's, in Pseudomonas strains the substrate specificities of all C230's are variable. The C230's expressed by the D-plasmids pBS241 and pBC311 have a moderate affinity for catechol, 3-methyl- and 4-methylcatechol, but are unable to cleave 2,3-dihydroxybiphenyl. The C230 which is encoded by the chromosomal structure gene from P. putida BF is very similar to C230 which codes for the TOL-plasmid pWWO. These plasmid differ from C230's expressed by biphenyl D-plasmids due to their capability to cleave 2,3-dihydroxybiphenyl in addition to catechol cleavage. All DBO's and C230's under study possess a number of properties that are typical for the enzymes having an oxidative meta-cleaving effect. The different roles of these enzymes in biphenyl and toluate catabolism in Pseudomonas strains are discussed.

Foundations of commutative rings and their modules

CERN Document Server

Wang, Fanggui

2016-01-01

This book provides an introduction to the basics and recent developments of commutative algebra. A glance at the contents of the first five chapters shows that the topics covered are ones that usually are included in any commutative algebra text. However, the contents of this book differ significantly from most commutative algebra texts: namely, its treatment of the Dedekind–Mertens formula, the (small) finitistic dimension of a ring, Gorenstein rings, valuation overrings and the valuative dimension, and Nagata rings. Going further, Chapter 6 presents w-modules over commutative rings as they can be most commonly used by torsion theory and multiplicative ideal theory. Chapter 7 deals with multiplicative ideal theory over integral domains. Chapter 8 collects various results of the pullbacks, especially Milnor squares and D+M constructions, which are probably the most important example-generating machines. In Chapter 9, coherent rings with finite weak global dimensions are probed, and the local ring of weak gl...

Interaction of ring dark solitons with ring impurities in Bose-Einstein condensates

International Nuclear Information System (INIS)

Xue Jukui

2005-01-01

The interaction of ring dark solitons/vortexes with the ring-shaped repulsive and attractive impurities in two-dimensional Bose-Einstein condensates is investigated numerically. Very rich interaction phenomena are obtained, i.e., not only the interaction between the ring soliton and the impurity, but also the interaction between vortexes and the impurity. The interaction characters, i.e., snaking of ring soliton, quasitrapping or reflection of ring soliton and vortexes by the impurity, strongly depend on initial ring soliton velocity, impurity strength, initial position of ring soliton and impurity. The numerical results also reveal that ring dark solitons/vortexes can be trapped and dragged by an adiabatically moving attractive ring impurity

INJECTION EFFICIENCY IN COMPTON RING NESTOR

Directory of Open Access Journals (Sweden)

P. I. Gladkikh

2017-12-01

Full Text Available NESTOR is the hard X-ray source that is under commissioning at NSC KIPT. NESTOR based on the Compton scattering of laser photons on relativistic electrons. The structure of the facility can be represented as the following components: a linear accelerator, a transport channel, a storage ring, and a laser-optical system. Electrons are stored in the storage ring for energy of 40-200 MeV. Inevitable alignment errors of magnetic elements are strongly effect on the beam dynamics in the storage ring. These errors lead to a shift of the equilibrium orbit relative to the ideal one. Significant shift of the equilibrium orbit could lead to loss of the beam on physical apertures. Transverse sizes of electron and laser beams are only few tens of microns at the interaction point. The shift of electron beam at the interaction point could greatly complicate the operation adjustment of storage ring without sufficient beam position diagnostic system. This article presents the simulation results of the efficiency of electron beam accumulation in the NESTOR storage ring. Also, this article is devoted to electron beam dynamics due to alignment errors of magnetic element in the ring.

Storage Rings

International Nuclear Information System (INIS)

Fischer, W.

2010-01-01

Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10 -6 eV to 3.5 x 10 12 eV (LHC, 7 x 10 12 eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or positron beams

Dielectric elastomer actuators using Slide-Ring Material® with increased permittivity

International Nuclear Information System (INIS)

Tsuchitani, Shigeki; Miki, Hirofumi; Sunahara, Tokiharu

2015-01-01

The inclusion of high permittivity nanoparticles in elastomeric materials for dielectric elastomer actuators (DEAs) is one promising method to achieve large strain at relatively low applied voltages. However, the addition of these nanoparticles tends to increase the stiffness of the elastomer and disturbs the actuation of the DEA. This is attributed to restriction of the chain motion in the elastomer by the nanoparticles. Slide-Ring Material ® (SRM) is a cross-linked polymeric material with freely movable cross-linking sites. The internal stresses in this structure are dramatically homogenized by the pulley effect; therefore, the restriction of chain motion due to the nanoparticles is expected to be significantly reduced. We have employed SRM as a host elastomer for a DEA with the addition of ferroelectric BaTiO 3 (BT) nanoparticles. The effects of BT addition on the permittivity, stiffness and viscosity of the SRM–BT nanocomposites, and the actuation strain of DEAs using SRM were evaluated. The permittivity of the nanocomposites increased linearly with the concentration of BT and reached 3.6 times that for pure SRM at 50 wt%. The elastic modulus and the viscosity remained almost constant up to 20 wt% and then decreased above this concentration. The actuation strain of a planar actuator using SRM and 50 wt% BT was four times larger than that of the DEA with pure SRM. (paper)

Small electrostatic storage rings; also for highly charged ions?

International Nuclear Information System (INIS)

Moeller, S.P.; Pedersen, U.V.

2001-01-01

Two years ago, a small electrostatic storage ring ELISA (electrostatic ion storage ring, Aarhus) was put into operation. The design of this small 7 m circumference ring was based on electrostatic deflection plates and quadrupoles. This is in contrast to the larger ion storage rings, which are based on magnetic focusing and deflection. The result is a small, relatively inexpensive, storage ring being able to store ions of any mass and any charge at low energy ( -11 mbar resulting in storage times of several tens of seconds for singly charged ions. The maximum number of singly charged ions that can be stored is a few 10 7 . Several experiments have already been performed in ELISA. These include lifetime studies of metastable ions and studies of fullerenes and metal-cluster ions. Lasers are also used for excitation of the circulating ions. Heating/cooling of the ring is possible. Cooling of the ring leads to significantly lower pressures, and correspondingly longer lifetimes. A change of the temperature of the vacuum chambers surrounding the ion beam also leads to a change of the spectrum of the black-body radiation, which has a significant influence on weakly bound negative ions. At the time of writing, at least two other electrostatic storage rings are being built, and more are planned. In the following, the electrostatic storage ring ELISA will be described, and results from some of the initial experiments demonstrating the performance will be shown. The relative merits of such a ring, as opposed to the larger magnetic rings and the smaller ion traps will be discussed. The potential for highly charged ions will be briefly mentioned. (orig.)

Generation of localized strain in a thin film piezoelectric to control individual magnetoelectric heterostructures

Energy Technology Data Exchange (ETDEWEB)

Cui, Jizhai; Liang, Cheng-Yen; Sepulveda, Abdon; Carman, Gregory P.; Lynch, Christopher S., E-mail: cslynch@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095 (United States); Paisley, Elizabeth A.; Ihlefeld, Jon F. [Electronic, Optical, and Nano Materials Department, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

2015-08-31

Experimental results demonstrate the ability of a surface electrode pattern to produce sufficient in-plane strain in a PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} (PZT) thin film clamped by a Si substrate to control magnetism in a 1000 nm diameter Ni ring. The electrode pattern and the Ni ring/PZT thin film heterostructure were designed using a finite element based micromagnetics code. The magnetoelectric heterostructures were fabricated on the PZT film using e-beam lithography and characterized using magnetic force microscopy. Application of voltage to the electrodes moved one of the “onion” state domain walls. This method enables the development of complex architectures incorporating strain-mediated multiferroic devices.

Type II GaSb/GaAs quantum dot/ring stacks with extended photoresponse for efficient solar cells

Energy Technology Data Exchange (ETDEWEB)

Carrington, Peter James, E-mail: p.carrington@lancaster.ac.uk [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Mahajumi, Abu Syed [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Wagener, Magnus C.; Botha, Johannes Reinhardt [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Zhuang Qian; Krier, Anthony [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2012-05-15

We report on the fabrication of GaAs based p-i-n solar cells containing 5 and 10 layers of type II GaSb quantum rings grown by molecular beam epitaxy. Solar cells containing quantum rings show improved efficiency at longer wavelengths into the near-IR extending up to 1500 nm and show enhanced short-circuit current under 1 sun illumination compared to a GaAs control cell. A reduction in the open-circuit voltage is observed due to the build-up of internal strain. The MBE growth, formation and photoluminescence of single and stacked layers of GaSb/GaAs quantum rings are also presented.

Type II GaSb/GaAs quantum dot/ring stacks with extended photoresponse for efficient solar cells

International Nuclear Information System (INIS)

Carrington, Peter James; Mahajumi, Abu Syed; Wagener, Magnus C.; Botha, Johannes Reinhardt; Zhuang Qian; Krier, Anthony

2012-01-01

We report on the fabrication of GaAs based p–i–n solar cells containing 5 and 10 layers of type II GaSb quantum rings grown by molecular beam epitaxy. Solar cells containing quantum rings show improved efficiency at longer wavelengths into the near-IR extending up to 1500 nm and show enhanced short-circuit current under 1 sun illumination compared to a GaAs control cell. A reduction in the open-circuit voltage is observed due to the build-up of internal strain. The MBE growth, formation and photoluminescence of single and stacked layers of GaSb/GaAs quantum rings are also presented.

Rings in drugs.

Science.gov (United States)

Taylor, Richard D; MacCoss, Malcolm; Lawson, Alastair D G

2014-07-24

We have analyzed the rings, ring systems, and frameworks in drugs listed in the FDA Orange Book to understand the frequency, timelines, molecular property space, and the application of these rings in different therapeutic areas and target classes. This analysis shows that there are only 351 ring systems and 1197 frameworks in drugs that came onto the market before 2013. Furthermore, on average six new ring systems enter drug space each year and approximately 28% of new drugs contain a new ring system. Moreover, it is very unusual for a drug to contain more than one new ring system and the majority of the most frequently used ring systems (83%) were first used in drugs developed prior to 1983. These observations give insight into the chemical novelty of drugs and potentially efficient ways to assess compound libraries and develop compounds from hit identification to lead optimization and beyond.

Initial clinical experience with a novel biodegradable ring in patients with functional tricuspid insufficiency: Kalangos Biodegradable Tricuspid Ring.

Science.gov (United States)

Burma, O; Ustunsoy, H; Davutoglu, V; Celkan, M A; Kazaz, H; Pektok, E

2007-08-01

Tricuspid annuloplasty procedures have been widely performed in clinics for many years. The Kalangos Biodegradable Tricuspid Ring (Kalangos Biodegradable Tricuspid Ring, Bioring SA, Lonay, Switzerland) is a novel prosthesis for the treatment of tricuspid insufficiency. The aim of this study was to evaluate the clinical and echocardiographic results of this novel prosthesis for functional tricuspid insufficiency. Between October 2005 and May 2006, 15 patients with the diagnosis of moderate or severe functional tricuspid insufficiency were treated by implantation of a Kalangos Biodegradable Tricuspid Ring. All patients were evaluated clinically and by echocardiography preoperatively, and control tests were performed at the end of the 1st and 6th month following surgery. Moderate and severe insufficiency was documented in 11 and 4 patients, respectively, in the preoperative tests. 1 and 6 months after surgery, 4 patients had trace and 1 patient had mild tricuspid insufficiency, while 10 patients had none. At the 1st and 6th month follow-up, systolic pulmonary arterial pressure, right atrial dimension and right ventricular diastolic diameter were found to be significantly lower than the preoperative values ( P tricuspid valve area had decreased significantly at the end of the 1st month; however, no significant difference was found between the 1st and 6th month tests ( P > 0.05). Three-quarters of the annuloplasty ring had degraded at 6 months. No complications related to the prosthesis or the procedure occurred within this period. Kalangos Biodegradable Ring is a promising prosthesis in patients with functional tricuspid insufficiency, with encouraging initial results.

A comparative study on the edge states in phosphorene quantum dots and rings

Energy Technology Data Exchange (ETDEWEB)

Jiang, Z.T., E-mail: jiangzhaotan@bit.edu.cn; Liang, F.X.; Zhang, X.D.

2017-01-30

Using the tight-binding Hamiltonian approach, we comparatively investigate the energy spectrums of triangular zigzag phosphorene quantum dots (PQDs) and rings (PQRs), as well as their potential applications. In comparison with the outer edge states in the PQD, new extra inner edge states can be produced in the PQR by its internal hole. A transition from the uncoupled to coupled edge states can be induced by decreasing the width between the outer and inner edges of the PQR. Also, the edge states in PQD/PQR are all anisotropically localized in one side, rather than three sides as in triangular graphene quantum dots (QDs) and rings (QRs). Furthermore, the PQD/PQR energy levels can be anisotropically manipulated by the external electric fields and strains, clearly demonstrating their potential applications in field effect transistors or electromechanical devices. In the meanwhile, we also consider the electron probability distributions corresponding to the different energy levels, clearly exposing the characteristics of the PQD/PQR energy levels. The comparison between the asymmetrical triangular PQDs/PQRs and the symmetrical triangular QDs/QRs in graphene should be instructive for understanding the similar triangular QDs/QRs in other two-dimensional layered materials, as well as other types of QDs/QRs of different shapes. - Highlights: • We make a comparative study on the energy levels of the phosphorene quantum dots and rings. • The energy levels can be anisotropically controlled by the electric field and the strains, different from those in graphene counterparts. • The edge states in phosphorene triangular quantum dot and rings are anisotropic. • A helpful reference for understanding phosphorene nanostructures of other shapes and designing devices.

New method to calculate the mechanical properties of unirradiated fuel cladding from ring tensile tests

Energy Technology Data Exchange (ETDEWEB)

Martin-Rengel, M.A. [Departamento de Ciencia de Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, Profesor Aranguren s/n, E-28040 Madrid (Spain); Consejo de Seguridad Nuclear (CSN), Justo Dorado 11, E-28040 Madrid (Spain); Gomez, F.J.; Ruiz-Hervias, J.; Caballero, L.; Valiente, A. [Departamento de Ciencia de Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, Profesor Aranguren s/n, E-28040 Madrid (Spain)

2009-06-15

Nuclear fuel cladding is the first barrier used to confine the fuel and the fission products produced during irradiation. Zirconium alloys are used for this purpose due to their remarkable neutron transparency, together with their good mechanical properties at operational temperatures. Consequently, it is very important to be able to characterize the mechanical response of the irradiated cladding. The mechanical behaviour of the material can be modelled as elastoplastic with different stress-strain curves depending on the direction: radial, hoop or longitudinal direction. The ring tensile test has been proposed to determine the mechanical properties of the cladding along the hoop direction. The initial test consisted of applying a force inside the tube, by means of two half cylinders. Later Arsene and Bai [1,2] modified the experimental device to avoid tube bending at the beginning of the test. The same authors proposed a numerical method to obtain the stress-strain curve in the hoop direction from the experimental load versus displacement results and a given friction coefficient between the loading pieces and the sample [3]. This method has been used by different authors [4] with slight modifications. It is based on the existence of two universal curves under small strain hypothesis: the first correlating the hoop strain and the displacement of the loading piece and the second one correlating the hoop stress and the applied load. In this work, a new method to determine the mechanical properties of the cladding from the ring tensile test results is proposed. Non-linear geometry is considered and an iterative procedure is proposed so universal curves are not needed. A stress-strain curve is determined by combining numerical calculations with experimental results in a convergent loop. The two universal curves proposed by Arsene and Bai [3] are substituted by two relationships, one between the equivalent plastic strain in the centre of the specimen ligament and the

Halo and space charge issues in the SNS Ring

International Nuclear Information System (INIS)

Fedotov, A.V.; Abell, D.T.; Beebe-Wang, J.; Lee, Y.Y.; Malitsky, N.; Wei, J.; Gluckstern, R.L.

2000-01-01

The latest designs for high-intensity proton rings require minimizing beam-induced radioactivation of the vacuum chamber. Although the tune depression in the ring is much smaller than in high-intensity linacs, space-charge contributions to halo formation and, hence, beam loss may be significant. This paper reviews our current understanding of halo formation issues for the Spallation Neutron Source (SNS) accumulator ring

Halo and space charge issues in the SNS Ring

Energy Technology Data Exchange (ETDEWEB)

Fedotov, A.V.; Abell, D.T.; Beebe-Wang, J.; Lee, Y.Y.; Malitsky, N.; Wei, J.; Gluckstern, R.L.

2000-06-30

The latest designs for high-intensity proton rings require minimizing beam-induced radioactivation of the vacuum chamber. Although the tune depression in the ring is much smaller than in high-intensity linacs, space-charge contributions to halo formation and, hence, beam loss may be significant. This paper reviews our current understanding of halo formation issues for the Spallation Neutron Source (SNS) accumulator ring.

Manufacturing of Nanostructured Rings from Previously ECAE-Processed AA5083 Alloy by Isothermal Forging

Directory of Open Access Journals (Sweden)

C. J. Luis

2013-01-01

Full Text Available The manufacturing of a functional hollow mechanical element or ring of the AA5083 alloy previously equal channel angular extrusion (ECAE processed, which presents a submicrometric microstructure, is dealt with. For this purpose, the design of two isothermal forging dies (preform and final shape is carried out using the design of experiments (DOE methodology. Moreover, after manufacturing the dies and carrying out tests so as to achieve real rings, the mechanical properties of these rings are analysed as well as their microstructure. Furthermore, a comparison between the different forged rings is made from ECAE-processed material subjected to different heat treatments, previous to the forging stage. On the other hand, the ring forging process is modelled through the use of finite element simulation in order to improve the die design and to study the force required for the isothermal forging, the damage value, and the strain the material predeformed by ECAE has undergone. With this present research work, it is intended to improve the knowledge about the mechanical properties of nanostructured material and the applicability of this material to industrial processes that allow the manufacturing of functional parts.

White Ring; White ring

Energy Technology Data Exchange (ETDEWEB)

Aoki, H.; Yuzawa, H. [Nikken Sekkei Ltd., Osaka (Japan)

1998-01-05

White Ring is a citizen`s gymnasium used for figure skating and short track speed skating games of 18th Winter Olympic Games in 1998. White Ring is composed of a main-arena and a sub-arena. For the main-arena with an area 41mtimes66m, an ice link can be made by disengaging the potable floor and by flowing brine in the bridged polystyrene pipes embedded in the concrete floor. Due to the fortunate groundwater in this site, well water is used for the outside air treatment energy in 63% during heating and in 35% during cooling. Ammonia is used as a cooling medium for refrigerating facility. For the heating of audience area in the large space, heat load from the outside is reduced by enhancing the heat insulation performance of the roof of arena. The audience seats are locally heated using heaters. For the White Ring, high quality environment is realized for games through various functions of the large-scale roof of the large space. Success of the big event was expected. 15 figs., 4 tabs.

Token Ring Project

Directory of Open Access Journals (Sweden)

Adela Ionescu

2007-01-01

Full Text Available Ring topology is a simple configuration used to connect processes that communicate among themselves. A number of network standards such as token ring, token bus, and FDDI are based on the ring connectivity. This article will develop an implementation of a ring of processes that communicate among themselves via pipe links. The processes are nodes in the ring. Each process reads from its standard input and writes in its standard output. N-1 process redirects the its standard output to a standard input of the process through a pipe. When the ring-structure is designed, the project can be extended to simulate networks or to implement algorithms for mutual exclusion

Breakaway frictions of dynamic O-rings in mechanical seals

Science.gov (United States)

Lai, Tom; Kay, Peter

1993-05-01

Breakaway friction of a dynamic O-ring affects the mechanical seal's response to large axial shaft movement and face wear. However, little data exist to help designers. Therefore, a test rig was developed to measure breakaway friction. The research quantitatively shows the effects of lubrication with silicone grease and a change of surface finish. By using the Taguchi statistical experimental design method, the significance of test parameters was evaluated with a minimum number of tests. It was found that fluid pressure, dwell time, and O-ring percentage squeeze affect O-ring breakaway friction more than the O-ring cross sectional diameter and axial sliding speed within the range of values tested. The authors showed that breakaway friction increased linearly with pressure. However, O-rings made of different materials had significantly different increase rates, even if they had nominally the same durometer hardness. Breakaway friction also increased with logarithm of dwell time. Again, the increase rate depended strongly on the specific O-ring material tested. These observations led the authors to believe that the typical approach of generalizing data based on generic polymer type and durometer was inappropriate.

Semi-algebraic function rings and reflectors of partially ordered rings

CERN Document Server

Schwartz, Niels

1999-01-01

The book lays algebraic foundations for real geometry through a systematic investigation of partially ordered rings of semi-algebraic functions. Real spectra serve as primary geometric objects, the maps between them are determined by rings of functions associated with the spectra. The many different possible choices for these rings of functions are studied via reflections of partially ordered rings. Readers should feel comfortable using basic algebraic and categorical concepts. As motivational background some familiarity with real geometry will be helpful. The book aims at researchers and graduate students with an interest in real algebra and geometry, ordered algebraic structures, topology and rings of continuous functions.

A girl with cutaneous hyperpigmentation, cafe au lait spots and ring chromosome 15 without significant deletion.

NARCIS (Netherlands)

Morava, E.; Bartsch, O.; Czako, M.; Frensel, A.; Karteszi, J.; Kosztolanyi, G.Y.

2003-01-01

Ring chromosome 15 [r(15)] syndrome is characterised by specific facial features, cafe au lait spots, failure to thrive, mental retardation and typically with a terminal deletion of the long arm of chromosome 15. We report a 2.5 year old girl showing normal growth and development, large

Rotating ring-ring electrode theory and experiment

NARCIS (Netherlands)

Kuiken, H.K.; Bakkers, E.P.A.M.; Ligthart, H.; Kellyb, J.J.

2000-01-01

A model is presented for the rotating ring-ring electrode. Although the electrode is defined by four characteristic lengths, it is shown that the collection efficiency depends on only two dimensionless parameters. A simple relationship between these and the corresponding parameters for the rotating

Preparation of strained axially chiral (1,5)naphthalenophanes by photo-dehydro-Diels-Alder reaction.

Science.gov (United States)

Wessig, Pablo; Matthes, Annika

2011-03-02

The preparation of 10 (1,5)naphthalenophanes (10a-j) by photo-dehydro-Diels-Alder (PDDA) reaction is described. Owing to hindered rotation around the biaryl axis, compounds 10 are axially chiral and the separation of enantiomers by chiral HPLC was demonstrated in three cases (10a,b,e). The absolute configuration of the isolated enantiomers could be unambiguously determined by comparison of calculated and measured circular dichroism (CD) spectra. Furthermore, we analyzed ring strain phenomena of (1,5)naphthalenophanes 10. Depending on the length of the linker units, one can distinguish three classes of naphthalenophanes. Compounds 10a-c are highly strained (E(STR) = 7-31 kcal/mol), and the strain is caused by small bond angles in the linker unit and deformation of the naphthalene moiety. Another type of strain is observed if the linker unit becomes relatively long (10g,h) originating from transannular interactions and is comparable with the well-known strain of medium sized rings. The naphthalenophanes 10d-f with a linker length of 10-14 atoms are only marginally strained. To clearly discriminate the different sources of strain, we defined two geometrical parameters (average central dihedral angle δ(C) and naphthalene thickness D(N)) and demonstrated that they are well-suited to indicate naphthalene deformation of our naphthalenophanes 10 as well as of ten model naphthalenophanes (I-X) with different linker lengths and linking positions.

Microstructure and micro-texture evolution during large strain deformation of aluminium alloy AA 2219

Energy Technology Data Exchange (ETDEWEB)

Murty, S.V.S. Narayana [Materials and Mechanical Entity, Vikram Sarabhai Space Center, Trivandrum-695 022 (India); Sarkar, Aditya [Department of Materials Science and Engineering, Indian Institute of Technology, Gandhinagar-382 424 (India); Narayanan, P. Ramesh; Venkitakrishnan, P.V. [Materials and Mechanical Entity, Vikram Sarabhai Space Center, Trivandrum-695 022 (India); Mukhopadhyay, J. [Department of Materials Science and Engineering, Indian Institute of Technology, Gandhinagar-382 424 (India)

2016-11-20

Aluminium alloy AA2219 is widely used in the fabrication of propellant tanks of cryogenic stages of satellite launch vehicles. These propellant tanks are welded structures and a fine grained microstructure is usually preferred for sheets/plates and ring rolled rings used in their fabrication. In order to study the effect of large strain deformation on the microstructural evolution, hot isothermal plane strain compression (PSC) tests were conducted on AA 2219 in the temperature range of 250 °C–400 °C and at strain rates of 0.01 s{sup −1} and 1 s{sup −1}. Flow curves obtained at different temperatures and strain rates exhibited two types of behavior; one with a clear stress peak followed by softening, occurring below Z=2.5E+15 and steady state flow behavior above it. Electron Back-Scatter Diffraction (EBSD) analysis of the PSC tested samples at the location of maximum strain revealed the presence of lamellar microstructures with very low fraction of transverse high angle boundaries (HABs). The loss of HABs during large strain deformation is attributed to the occurrence of dynamic recovery (DRV) as the ratio of calculated to measured lamellar boundary width is less than unity. Based on detailed microstructure and micro texture analysis, it was concluded that it is very difficult to obtain large fraction of HABs through uniaxial large strain deformation. Therefore, to obtain fine grain microstructure in thermo-mechanically processed AA2219 products, multi-axial deformation is essential.

Topological ring currents in the "empty" ring of benzo-annelated perylenes.

Science.gov (United States)

Dickens, Timothy K; Mallion, Roger B

2011-01-27

Cyclic conjugation in benzo-annelated perylenes is examined by means of the topological π-electron ring currents calculated for each of their constituent rings, in a study that is an exact analogy of a recent investigation by Gutman et al. based on energy-effect values for the corresponding rings in each of these structures. "Classical" approaches, such as Kekulé structures, Clar "sextet" formulas, and circuits of conjugation, predict that the central ring in perylene is "empty" and thus contributes negligibly to cyclic conjugation. However, conclusions from the present calculations of topological ring currents agree remarkably with those arising from the earlier study involving energy-effect values in that, contrary to what would be predicted from the classical approaches, rings annelated in an angular fashion relative to the central ring of these perylene structures materially increase the extent of that ring's involvement in cyclic conjugation. It is suggested that such close quantitative agreement between the predictions of these two superficially very different indices (energy effect and topological ring current) might be due to the fact that, ultimately, both depend, albeit in ostensibly quite different ways, only on an adjacency matrix that contains information about the carbon-carbon connectivity of the conjugated system in question.

The ring plus project: safety and acceptability of vaginal rings that protect women from unintended pregnancy.

Science.gov (United States)

Schurmans, Céline; De Baetselier, Irith; Kestelyn, Evelyne; Jespers, Vicky; Delvaux, Thérèse; Agaba, Stephen K; van Loen, Harry; Menten, Joris; van de Wijgert, Janneke; Crucitti, Tania

2015-04-10

Research is ongoing to develop multipurpose vaginal rings to be used continuously for contraception and to prevent Human Immunodeficiency Virus (HIV) infection. Contraceptive vaginal rings (CVRs) are available in a number of countries and are most of the time used intermittently i.e. three weeks out of a 4-week cycle. Efficacy trials with a dapivirine-containing vaginal ring for HIV prevention are ongoing and plans to develop multi-purpose vaginal rings for prevention of both HIV and pregnancy have been elaborated. In contrast with the CVRs, multi-purpose vaginal rings will have to be used continuously. Women who continuously use a CVR will no longer have menses. Furthermore, some safety aspects of CVR use have never been studied in-depth in the past, such as the impact of the vaginal ring on the vaginal microbiota, biofilm formation and induction of inflammation. We studied acceptability and these novel aspects of safety in Rwandan women. Although significant progress has been made over the past decade, Rwanda still has a high unmet need for contraception (with 47% unplanned births) and a generalized HIV epidemic, and CVRs are not yet available. We will conduct an open label, single centre, randomized controlled trial. A total of 120 HIV-negative women will be randomized to intermittent CVR use (to allow menstruation) or continuous CVR use. Women will be followed for a maximum of 14 weeks. In parallel, we will conduct a qualitative study using in-depth interview and focus group discussion methodology. In addition to evaluating the safety and acceptability of intermittent and continuous CVR use in Rwandan women, we hope that our findings will inform the development of future multipurpose vaginal rings, will prepare Rwandan study populations for future clinical trials of multipurpose vaginal rings, and will pave the way for introduction of CVRs on African markets. Clinicaltrials.gov NCT01796613 . Registered 14 February 2013.

Ion-ion collisions and ion storage rings

International Nuclear Information System (INIS)

Mowat, J.R.

1988-01-01

Improved understanding of fundamental ion-ion interactions is expected to emerge from research carried out with ion storage rings. In this short survey the significant advantages and unique features that make stored ions useful targets for collision experiments are reviewed and discussed. It is pointed out that improvements to existing ion-ion experiments, as well as qualitatively new experiments, should occur over the next few years as ion storage rings become available for atomic physics. Some new experiments are suggested which are difficult if not impossible with present-day technology, but which seem feasible at storage rings facilities. (orig.)

Kayser-Fleischer Rings

Science.gov (United States)

... Support Contacts Lab Tracker/Copper Calculator Stories Programs & Research ... About Everything you need to know about Wilson Disease Kayser-Fleischer Rings Definition Kayser-Fleischer Ring: Clinical sign. Brownish-yellow ring visible around the corneo- ...

Planetary Rings

Science.gov (United States)

Nicholson, P. D.

2001-11-01

A revolution in the studies in planetary rings studies occurred in the period 1977--1981, with the serendipitous discovery of the narrow, dark rings of Uranus, the first Voyager images of the tenuous jovian ring system, and the many spectacular images returned during the twin Voyager flybys of Saturn. In subsequent years, ground-based stellar occultations, HST observations, and the Voyager flybys of Uranus (1986) and Neptune (1989), as well as a handful of Galileo images, provided much additional information. Along with the completely unsuspected wealth of detail these observations revealed came an unwelcome problem: are the rings ancient or are we privileged to live at a special time in history? The answer to this still-vexing question may lie in the complex gravitational interactions recent studies have revealed between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto parent bodies. Perhaps most puzzling is Saturn's multi-stranded, clumpy F ring, which continues to defy a simple explanation 20 years after it was first glimpsed in grainy images taken by Pioneer 11. Voyager and HST images reveal a complex, probably chaotic, dynamical interaction between unseen parent bodies within this ring and its two shepherd satellites, Pandora and Prometheus. The work described here reflects contributions by Joe Burns, Jeff Cuzzi, Luke Dones, Dick French, Peter Goldreich, Colleen McGhee, Carolyn Porco, Mark Showalter, and Bruno Sicardy, as well as those of the author. This research has been supported by NASA's Planetary Geology and Geophysics program and the

Early Clinical Outcomes of Tricuspid Valve Repair with a Tri-Ad Annuloplasty Ring in Comparison with the Outcomes Using an MC³ Ring

Directory of Open Access Journals (Sweden)

Woohyun Jung

2018-04-01

Full Text Available Background: We evaluated the early clinical outcomes of tricuspid valve annuloplasty (TAP with the Tri-Ad annuloplasty ring for functional tricuspid regurgitation (TR. Methods: From January 2015 to March 2017, 36 patients underwent TAP with a Tri-Ad ring for functional TR. To evaluate the early clinical outcomes of TAP with the Tri-Ad ring, we conducted a propensity score-matched analysis comparing the Tri-Ad and MC³ tri-cuspid annuloplasty rings (n=34 in each group. The follow-up duration was 11.0±7.07 months. Results: There was 1 case of operative mortality (2.8% and no cases of late mortality. Postoperative complications occurred in 15 patients (41%, including acute kidney injury in 6 patients (16%, bleeding requiring reoperation in 4 patients (11%, and low cardiac output syndrome in 4 patients (11%. There were no ring-related complications, such as atrioventricular block or ring dehiscence. The TR grade decreased significantly (from 2.03±1.06 to 1.18±0.92, p<0.01, as did the systolic pulmonary artery pressure (from 43.53±13.84 to 38.00±9.72 mm Hg, p=0.03. There were no cases of severe residual TR, but moderate TR was observed in 3 patients, all of whom had severe TR preoperatively. Severe preoperative TR was also associated with moderate in the univariate analysis (p<0.01. In the propensity score-matched analysis comparing the Tri-Ad and MC³ rings, there was no significant difference in early clinical outcomes. Conclusion: TAP with the Tri-Ad ring corrected functional TR effectively and provided good early clinical and echocardiographic results without ring-related complications. However, severe preoperative TR was associated with moderate or severe residual TR in the immediate postoperative period. A follow-up study is necessary to confirm the stability of this procedure.

Modeling Restrained Shrinkage Induced Cracking in Concrete Rings Using the Thick Level Set Approach

Directory of Open Access Journals (Sweden)

Rebecca Nakhoul

2018-03-01

Full Text Available Modeling restrained shrinkage-induced damage and cracking in concrete is addressed herein. The novel Thick Level Set (TLS damage growth and crack propagation model is used and adapted by introducing shrinkage contribution into the formulation. The TLS capacity to predict damage evolution, crack initiation and growth triggered by restrained shrinkage in absence of external loads is evaluated. A study dealing with shrinkage-induced cracking in elliptical concrete rings is presented herein. Key results such as the effect of rings oblateness on stress distribution and critical shrinkage strain needed to initiate damage are highlighted. In addition, crack positions are compared to those observed in experiments and are found satisfactory.

Preparation for electron ring - plasma ring merging experiments in RECE-MERGE

International Nuclear Information System (INIS)

Taggart, D.; Sekiguchi, A.; Fleischmann, H.H.

1986-01-01

The formation of a mixed-CT using relativistic electron rings and gun-produced plasma rings by MERGE-ing them axially is simulated. This process is similar to the axial stacking of relativistic electron rings in RECE-Christa. The results of their first plasm production experiment are reported here. After study of the gun-produced plasma's properties is completed, the gun will be mounted at the downstream end of the vacuum tank and the source of relativistic electron rings will be at the upstream end. The two rings, formed at opposite ends of the tank, will be translated axially and merged

Revisiting shape selectivity in liquid chromatography for polycyclic aromatic hydrocarbons (PAHs) - six-ring and seven-ring Cata-condensed PAH isomers of molecular mass 328 Da and 378 Da.

Science.gov (United States)

Oña-Ruales, Jorge O; Sander, Lane C; Wilson, Walter B; Wise, Stephen A

2018-01-01

The relationship of reversed-phase liquid chromatography (RPLC) retention on a polymeric C 18 stationary phase and the shape of polycyclic aromatic hydrocarbons (PAHs) was investigated for three-ring to seven-ring cata-condensed isomers. We report the first RPLC separation for six-ring and seven-ring cata-condensed PAH isomers. Correlations of LC retention and shape parameters (length-to-breath ratio, L/B and thickness, T) were investigated for 2 three-ring isomers (molecular mass 178 Da), 5 four-ring isomers (molecular mass 228 Da), 11 five-ring isomers (molecular mass 278 Da), 17 six-ring isomers (molecular mass 328 Da), and 20 seven-ring isomers (molecular mass 378 Da). Significant linear correlations were found for all isomer groups (r = 0.71 to 0.94). Nonplanarity of the PAH isomers was found to influence retention (i.e., nonplanar isomers eluting earlier than expected based on L/B) and linear correlations of retention vs. T for isomer groups containing nonplanar isomers were significant (r = 0.71 to 0.86). Graphical abstract.

The Transition from Volcanic to Rift Dominated Crustal Breakup - From the Vøring Plateau to the Lofoten Margin, Norway

Science.gov (United States)

Breivik, A. J.; Faleide, J. I.; Mjelde, R.; Flueh, E.; Murai, Y.

2017-12-01

The Vøring Plateau was part of the Northeast Atlantic igneous province (NAIP) during early Cenozoic crustal breakup. Crustal breakup at the Vøring Plateau occurred marginal to the deep Cretaceous basins on the shelf, with less extension of the crust. Intrusive magmatism and oceanic crust up to three times normal thickness caused a period of sub-aerial magmatism around breakup time. The transition to the Lofoten Margin is rapid to a deep-water plain. Still, there is some excess magmatism north of this transition, where early oceanic crustal thickness is reduced to half of that of the Vøring Plateau 150 km away. Our estimates of the earliest seafloor spreading rates using new ship-track magnetic profiles on different margin segments offer a clue to what caused this rapid transition. While crustal breakup occurred within the magnetic polarity C24r in other parts of the NAIP, there is a delayed breakup for the Lofoten/Vesterålen margin. Modeling of the earliest seafloor spreading with geomagnetic reversals, indicate a breakup within C24n.3n (anomaly 24b), approximately 1 m.y. later. Both old wide-angle seismic models (from Ocean Bottom Seismometers) off southern Lofoten and a newly published profile farther north show a strongly extended outer margin. Applying early seafloor half-spreading rates ( 30 mm/y) from other NAIP margin segments for 1 m.y. can account for 30 km extra extension, giving a factor of three crustal thinning, and gives a high strain rate of 3.2 ·10-14. Crustal breakup at the magma-poor Iberian Margin occurred at a low strain rate of 4.4·10-15, allowing the ascending mantle to cool, favoring tectonic extension over magmatism. Similar strain rates are found within the main Ethiopian Rift, but there is much magmatism and crustal separation is dominated by dike injection. Mantle tomography models show an exceptionally low seismic velocity below the area interpreted as an unusually hot upper mantle, which will favor magmatism. The transition from

Atomic cranks and levers control sugar ring conformations

International Nuclear Information System (INIS)

Zhang Qingmin; Lee, Gwangrog; Marszalek, Piotr E

2005-01-01

In this paper we review the conformational analysis of sugar rings placed under tension during mechanical manipulations of single polysaccharide molecules with the atomic force microscope and during steered molecular dynamics simulations. We examine the role of various chemical bonds and linkages between sugar rings in inhibiting or promoting their conformational transitions by means of external forces. Small differences in the orientation of one chemical bond on the sugar ring can produce significantly different mechanical properties at the polymer level as exemplified by two polysaccharides: cellulose, composed of β-1→4-linked D-glucose, and amylose, composed of α-1→4-linked D-glucose. In contrast to β-glucose rings, which are mechanically stable and produce simple entropic elasticity of the chain, α-glucose rings flip under tension from their chair to a boat-like structure and these transitions produce deviations of amylose elasticity from the freely jointed chain model. We also examine the deformation of two mechanically complementary 1→6-linked polysaccharides: pustulan, a β-1→6-linked glucan, and dextran, a α-1→6-linked glucan. Forced rotations about the C 5 -C 6 bonds govern the elasticity of pustulan, and complex conformational transitions that involve simultaneous C 5 -C 6 rotations and chair-boat transitions govern the elasticity of dextran. Finally, we discuss the likelihood of various conformational transitions in sugar rings in biological settings and speculate on their significance

Physiological Responses during Cycling With Oval Chainrings (Q-Ring) and Circular Chainrings.

Science.gov (United States)

Cordova, Alfredo; Latasa, Iban; Seco, Jesus; Villa, Gerardo; Rodriguez-Falces, Javier

2014-05-01

The aim of this study was to compare the physiological responses of cyclists using round (C-ring) or oval (Q-ring) chainrings during an incremental test until exhaustion. Following a randomized design, twelve male elite cyclists [age (mean ± SD): 21.1 ± 2.1 yr; VO2max: 78.1 ± 5.3 mL·kg(-1)min(-1)] performed two incremental maximal tests separated by 48 h (one with C-rings, the other with Q-rings). Starting at 100 W, the workload was increased by 25 W every 3 min until volitional exhaustion. Maximal heart rate, power output and oxygen consumption were compared. Blood lactate was monitored throughout the test. After the incremental test, 4 intermittent 20-s maximal sprints with a 60-s recovery period in between were performed. Maximal isometric voluntary contractions were performed at rest and immediately after each 20-s maximal sprint, and the force and EMG RMS amplitude were recorded from the vastus medialis and vastus lateralis muscles. For the incremental exercise test, no significant differences were found in the maximal power output (P=0.12), oxygen consumption (P=0.39), and heart rate (P=0.32) between Q-rings and C-rings. Throughout the incremental test, lactate levels were comparable when using both the C-rings and Q-rings (P=0.47). During the short sprints, power output was 2.5-6.5% greater for Q-rings than for C-rings (P=0.22). The decline in EMG RMS amplitude observed during the incremental tests was comparable for Q-rings and C-rings (0.42). These findings indicate that the oval chainring design, presented here as "Q-rings", did not significantly influence the physiological response to an incremental exercise test as compared to a conventional chainring. Key pointsDuring the incremental exercise test, no significant differences were found in power output, oxygen consumption or heart rate between oval "Q-rings" and conventional chainrings.Over the course of the incremental test, blood lactate levels were comparable for the oval "Q-rings" and

Scalar mixing and strain dynamics methodologies for PIV/LIF measurements of vortex ring flows

OpenAIRE

Bouremel, Y.; Ducci, A.

2017-01-01

Fluid mixing operations are central to possibly all chemical, petrochemical, and pharmaceutical industries either being related to biphasic blending in polymerisation processes, cell suspension for biopharmaceuticals production, and fractionation of complex oil mixtures. This work aims at providing a fundamental understanding of the mixing and stretching dynamics occurring in a reactor in the presence of a vortical structure, and the vortex ring was selected as a flow paradigm of vortices com...

Stress analysis of HLW containers. Preliminary ring test exercise Compas project

International Nuclear Information System (INIS)

1989-01-01

This document describes the series of experiments and associated calculations performed as the Compas preliminary ring test exercise. A number of mild steel rings, representative of sections through HLW containers, some notched and pre-cracked, were tested in compression right up to and beyond their ultimate load. The Compas project partners independently modelled the behaviour of these rings using their finite element codes. Four different ring types were tested, and each test was repeated three times. For three of the ring types, the three test repetitions gave identical results. The fourth ring, which was not modelled by the partners, had a 4 mm thick layer of weld metal deposited on its surface. The three tests on this ring did not give identical results and suggested that the effect of welding methods should be addressed at a later stage of the project. Fracture was not found to be a significant cause of ring failure. The results of the ring tests were compared with the partners predictions, and additionally some time was spent assessing where the use of the codes could be improved. This exercise showed that the partners codes have the ability to produce results within acceptable limits. Most codes were unable to model stable crack growth. There were indications that some codes would not be able to cope with a significantly more complex three-dimensional analysis

Comparing Sources of Storm-Time Ring Current O+

Science.gov (United States)

Kistler, L. M.

2015-12-01

The first observations of the storm-time ring current composition using AMPTE/CCE data showed that the O+ contribution to the ring current increases significantly during storms. The ring current is predominantly formed from inward transport of the near-earth plasma sheet. Thus the increase of O+ in the ring current implies that the ionospheric contribution to the plasma sheet has increased. The ionospheric plasma that reaches the plasma sheet can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma sheet through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma sheet. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the tail at ~15-20 Re becomes isotropized when it crosses the neutral sheet, and becomes part of the hot (>1 keV) plasma sheet population as it convects inward. The auroral outflow, which enters the plasma sheet closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma sheet population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring current pressure. Thus it appears that O+ that enters the plasma sheet further down the tail has a greater impact on the storm-time ring current than ions that enter closer to the earth.

BIOBUTANOL ACCUMULATION USING ALTERNATIVE SUBSTRATES BY CULTIVATION OF Clostridium acetobutylicum STRAINS

Directory of Open Access Journals (Sweden)

О. О. Тigunova

2017-10-01

Full Text Available The aim of the research was to investigate the accumulation of biobutanol by strains Clostridium acetobutylicum using alternative substrates (Jerusalem artichoke juice, technical glycerol, crude glycerol, shredded biomass of soy, rape, wheat and switchgrass. In order to increase the accumulation of butanol in the process of cultivation, the cells of C. acetobutylicum were statically immobilized on carriers (belting strips, ferrite rings and Raschig rings by the method of adsorption immobilization. The cells were precipitated by centrifugation, the supernatant was distilled and then fermentation products were determined. Gas chromatography was used to determine the presence of solvents in the culture fluid. The biggest accumulation of butanol (2 g/dm3 was at concentration of crude glycerol 16 g/dm3 in the medium, and complete inhibition of culture development — at glycerol concentration 25 g/dm3. The accumulation of butanol by the strain C. acetobutylicum ІМВ В-7407 using fill and draw method depended on the amount of sequestered and infused medium. Immobilization of the culture using the Raschig rings allowed increasing the bioconversion to butanol twice. So it is shown the possibility to use non-traditional substrates for the production of biobutanol. The most accumulation of butanol was achieved using glycerol (11 g/dm3 as water-soluble substrate, and using switchgrass as lignocelluloses substrate (2,6 g/dm3. Immobilization of C. acetobutylicum culture cells on carriers increased the accumulation of butanol. The use of Raschig rings, as carriers for immobilization, allowed increasing the accumulation of butanol twice.

Ringed Accretion Disks: Evolution of Double Toroidal Configurations

Energy Technology Data Exchange (ETDEWEB)

Pugliese, D.; Stuchlík, Z., E-mail: daniela.pugliese@fpf.slu.cz, E-mail: zdenek.stuchlik@physics.cz [Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo náměstí 13, CZ-74601 Opava (Czech Republic)

2017-04-01

We investigate ringed accretion disks composed of two tori (rings) orbiting on the equatorial plane of a central supermassive Kerr black hole. We discuss the emergence of the instability phases of each ring of the macro-configuration (ringed disk) according to the Paczynski violation of mechanical equilibrium. In the full general relativistic treatment, we consider the effects of the geometry of the Kerr spacetimes relevant to the characterization of the evolution of these configurations. The discussion of ring stability in different spacetimes enables us to identify particular classes of central Kerr attractors depending on their dimensionless spin. As a result of this analysis, we set constraints on the evolutionary schemes of the ringed disks relative to the torus morphology and on their rotation relative to the central black hole and to each other. The dynamics of the unstable phases of this system is significant for the high-energy phenomena related to accretion onto supermassive black holes in active galactic nuclei and the extremely energetic phenomena in quasars, which could be observed in their X-ray emission.

Evaluation of Residual Stresses using Ring Core Method

Directory of Open Access Journals (Sweden)

Holý S.

2010-06-01

Full Text Available The method for measuring residual stresses using ring-core method is described. Basic relations are given for residual stress measurement along the specimen depth and simplified method is described for average residual stress estimation in the drilled layer for known principal stress directions. The estimation of calculated coefficients using FEM is described. Comparison of method sensitivity is made with hole-drilling method. The device for method application is described and an example of experiment is introduced. The accuracy of method is discussed. The influence of strain gauge rosette misalignment to the evaluated residual stresses is performed using FEM.

Ring faults and ring dikes around the Orientale basin on the Moon.

Science.gov (United States)

Andrews-Hanna, Jeffrey C; Head, James W; Johnson, Brandon; Keane, James T; Kiefer, Walter S; McGovern, Patrick J; Neumann, Gregory A; Wieczorek, Mark A; Zuber, Maria T

2018-08-01

The Orientale basin is the youngest and best-preserved multiring impact basin on the Moon, having experienced only modest modification by subsequent impacts and volcanism. Orientale is often treated as the type example of a multiring basin, with three prominent rings outside of the inner depression: the Inner Rook Montes, the Outer Rook Montes, and the Cordillera. Here we use gravity data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission to reveal the subsurface structure of Orientale and its ring system. Gradients of the gravity data reveal a continuous ring dike intruded into the Outer Rook along the plane of the fault associated with the ring scarp. The volume of this ring dike is ~18 times greater than the volume of all extrusive mare deposits associated with the basin. The gravity gradient signature of the Cordillera ring indicates an offset along the fault across a shallow density interface, interpreted to be the base of the low-density ejecta blanket. Both gravity gradients and crustal thickness models indicate that the edge of the central cavity is shifted inward relative to the equivalent Inner Rook ring at the surface. Models of the deep basin structure show inflections along the crust-mantle interface at both the Outer Rook and Cordillera rings, indicating that the basin ring faults extend from the surface to at least the base of the crust. Fault dips range from 13-22° for the Cordillera fault in the northeastern quadrant, to 90° for the Outer Rook in the northwestern quadrant. The fault dips for both outer rings are lowest in the northeast, possibly due to the effects of either the direction of projectile motion or regional gradients in pre-impact crustal thickness. Similar ring dikes and ring faults are observed around the majority of lunar basins.

Propellers in Saturn's rings

Science.gov (United States)

Sremcevic, M.; Stewart, G. R.; Albers, N.; Esposito, L. W.

2013-12-01

high and relatively low optical depth. From the radial separation of the propeller wings we estimate that the embedded body is about 1.5km in size. In addition to the population of "big" propellers we found evidence for a population of much smaller propellers which are more similar to known A ring propellers (size r=94,958km. The feature represents a gap with a width of 300m. This gap is statistically significant and consists of 6 consequent high counts. All other UVIS occultations show a flat and boring profile at this location. The r=94,958km feature is very similar in shape and size to a known detection of A ring propeller Bleriot from zeta Persei Rev42 occultation. This feature is also found as a dark spot moving at Kepler speed across several ISS images. Additionally we found 5 more small propeller candidates in ISS images of the inner B ring.

Groups, rings, modules

CERN Document Server

Auslander, Maurice

2014-01-01

This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

Saturn's Rings Edge-on

Science.gov (United States)

1995-01-01

In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.This image and other images and

The Rotating Ring-Ring Electrode. Theory and Experiment

NARCIS (Netherlands)

Kuiken, H.K.; Bakkers, E.P.A.M.; Ligthart, H.; Kelly, J.J.

2000-01-01

A model is presented for the rotating ring-ring electrode. Although the electrode is defined by four characteristic lengths, it is shown that the collection efficiency depends on only two dimensionless parameters. A simple relationship between these and the corresponding parameters for the rotating

Wear Analysis of Top Piston Ring to Reduce Top Ring Reversal Bore Wear

Directory of Open Access Journals (Sweden)

P. Ilanthirayan

2017-12-01

Full Text Available The piston rings are the most important part in engine which controls the lubricating oil consumption and blowby of the gases. The lubricating film of oil is provided to seal of gases towards crankcase and also to give smooth friction free translatory motion between rings and liner. Of the three rings present top ring is more crucial as it does the main work of restricting gases downwards the crankcase. Boundary lubrication is present at the Top dead centre (TDC and Bottom dead centre (BDC of the liner surface. In addition to this, top ring is exposed to high temperature gases which makes the oil present near the top ring to get evaporated and decreasing its viscosity, making metal-metal contact most of the time. Due to this at TDC, excess wear happens on the liner which is termed as Top ring reversal bore wear. The wear rate depends upon many parameters such as lubrication condition, viscosity index, contact type, normal forces acting on ring, geometry of ring face, surface roughness, material property. The present work explores the wear depth for different geometries of barrel ring using Finite Element model with the help of Archard wear law and the same is validated through experimentation. The study reveals that Asymmetric barrel rings have less contact pressure which in turn reduces the wear at Top dead centre.

Tree-ring variation in teak (Tectona grandis L.) from Allapalli ...

Indian Academy of Sciences (India)

region. Tree-ring variations were most correlated positively with PDSI during different seasons ... significant role in the development of annual growth rings. ..... (which is an integration of precipitation and mean ..... This shows that the network of.

Vortex rings

CERN Document Server

Akhmetov, D G

2009-01-01

This text on vortex rings covers their theoretical foundation, systematic investigations, and practical applications such as the extinction of fires at gushing oil wells. It pays special attention to the formation and motion of turbulent vortex rings.

Accretion in Saturn's F Ring

Science.gov (United States)

Meinke, B. K.; Esposito, L. W.; Stewart, G.

2012-12-01

Saturn's F ring is the solar system's principal natural laboratory for direct observation of accretion and disruption processes. The ring resides in the Roche zone, where tidal disruption competes with self-gravity, which allows us to observe the lifecycle of moonlets. Just as nearby moons create structure at the B ring edge (Esposito et al. 2012) and the Keeler gap (Murray 2007), the F ring "shepherding" moons Prometheus and Pandora stir up ring material and create observably changing structures on timescales of days to decades. In fact, Beurle et al (2010) show that Prometheus makes it possible for "distended, yet gravitationally coherent clumps" to form in the F ring, and Barbara and Esposito (2002) predicted a population of ~1 km bodies in the ring. In addition to the observations over the last three decades, the Cassini Ultraviolet Imaging Spectrograph (UVIS) has detected 27 statistically significant features in 101 occultations by Saturn's F ring since July 2004. Seventeen of those 27 features are associated with clumps of ring material. Two features are opaque in occultation, which makes them candidates for solid objects, which we refer to as Moonlets. The 15 other features partially block stellar signal for 22 m to just over 3.7 km along the radial expanse of the occultation. Upon visual inspection of the occultation profile, these features resemble Icicles, thus we will refer to them as such here. The density enhancements responsible for such signal attenuations are likely due to transient clumping of material, evidence that aggregations of material are ubiquitous in the F ring. Our lengthy observing campaign reveals that Icicles are likely transient clumps, while Moonlets are possible solid objects. Optical depth is an indicator of clumping because more-densely aggregated material blocks more light; therefore, it is natural to imagine moonlets as later evolutionary stage of icicle, when looser clumps of material compact to form a feature that appears

FUZZY RINGS AND ITS PROPERTIES

Directory of Open Access Journals (Sweden)

Karyati Karyati

2017-01-01

  One of algebraic structure that involves a binary operation is a group that is defined  an un empty set (classical with an associative binary operation, it has identity elements and each element has an inverse. In the structure of the group known as the term subgroup, normal subgroup, subgroup and factor group homomorphism and its properties. Classical algebraic structure is developed to algebraic structure fuzzy by the researchers as an example semi group fuzzy and fuzzy group after fuzzy sets is introduced by L. A. Zadeh at 1965. It is inspired of writing about semi group fuzzy and group of fuzzy, a research on the algebraic structure of the ring is held with reviewing ring fuzzy, ideal ring fuzzy, homomorphism ring fuzzy and quotient ring fuzzy with its properties. The results of this study are obtained fuzzy properties of the ring, ring ideal properties fuzzy, properties of fuzzy ring homomorphism and properties of fuzzy quotient ring by utilizing a subset of a subset level  and strong level  as well as image and pre-image homomorphism fuzzy ring.   Keywords: fuzzy ring, subset level, homomorphism fuzzy ring, fuzzy quotient ring

THE RINGS OF CHARIKLO UNDER CLOSE ENCOUNTERS WITH THE GIANT PLANETS

Energy Technology Data Exchange (ETDEWEB)

Araujo, R. A. N.; Sfair, R.; Winter, O. C., E-mail: ran.araujo@gmail.com, E-mail: rsfair@feg.unesp.br, E-mail: ocwinter@gmail.com [UNESP - Univ. Estadual Paulista, Grupo de Dinâmica Orbital e Planetologia, CEP 12516-410, Guaratingueta, SP (Brazil)

2016-06-20

The Centaur population is composed of minor bodies wandering between the giant planets that frequently perform close gravitational encounters with these planets, leading to a chaotic orbital evolution. Recently, the discovery of two well-defined narrow rings was announced around the Centaur 10199 Chariklo. The rings are assumed to be in the equatorial plane of Chariklo and to have circular orbits. The existence of a well-defined system of rings around a body in such a perturbed orbital region poses an interesting new problem. Are the rings of Chariklo stable when perturbed by close gravitational encounters with the giant planets? Our approach to address this question consisted of forward and backward numerical simulations of 729 clones of Chariklo, with similar initial orbits, for a period of 100 Myr. We found, on average, that each clone experiences during its lifetime more than 150 close encounters with the giant planets within one Hill radius of the planet in question. We identified some extreme close encounters that were able to significantly disrupt or disturb the rings of Chariklo. About 3% of the clones lose their rings and about 4% of the clones have their rings significantly disturbed. Therefore, our results show that in most cases (more than 90%), the close encounters with the giant planets do not affect the stability of the rings in Chariklo-like systems. Thus, if there is an efficient mechanism that creates the rings, then these structures may be common among these kinds of Centaurs.

Comparison of disposable sutureless silicone ring and traditional metal ring in 23-gauge vitrectomy combined with cataract surgery.

Science.gov (United States)

Wu, Jian-Guo; Wei, Rui-Hua; Liu, Ai-Hua; Zhou, Xiao-Xu; Sun, Guo-Ling; Li, Xiao-Rong

2011-01-01

The purpose of this prospective, interventional, comparative case series was to evaluate the efficiency and feasibility of a disposable sutureless silicone lens ring for corneal contact lens stabilization during combined 23-gauge vitrectomy and cataract surgery. We developed a ring consisting of a single silicone component with three footplates along the ring margin to fit cannulae for holding conventional contact lenses. Thirty eyes from 30 patients with cataract and vitreoretinal disease were included, and divided into two matched groups according to disease type and ring used. In Group A, we used a 23-gauge transconjunctival vitrectomy system and a disposable sutureless silicone lens ring (n = 15). In Group B, we used a 23-gauge transconjunctival vitrectomy system and a conventional metal lens ring (n = 15). The main outcome measures were: time required for vitrectomy preparation, rate of intraoperative corneal limbus bleeding, and limbus scar rate at the final follow-up visit. Thirty cases were successfully completed. The average vitrectomy preparation time was less in Group A than in Group B (P < 0.01), and the average preparation time saved was 3.94 minutes. None of the Group A patients had intraoperative bleeding or postoperative scarring, whereas all 15 Group B cases had bleeding and five had scarring. There was a statistically significant difference between Group A and Group B for these complications (P ≤ 0.05). This report demonstrates the advantages of using a sutureless silicone ring during combined 23-gauge vitrectomy and cataract surgery. Using this method could allow extra time for the surgeon to pay more attention to complex vitreoretinal procedures.

Polarization Insensitivity in Double-Split Ring and Triple-Split Ring Terahertz Resonators

International Nuclear Information System (INIS)

Wu Qian-Nan; Lan Feng; Tang Xiao-Pin; Yang Zi-Qiang

2015-01-01

A modified double-split ring resonator and a modified triple-split ring resonator, which offer polarization-insensitive performance, are investigated, designed and fabricated. By displacing the two gaps of the conventional double-split ring resonator away from the center, the second resonant frequency for the 0° polarized wave and the resonant frequency for the 90° polarized wave become increasingly close to each other until they are finally identical. Theoretical and experimental results show that the modified double-split ring resonator and the modified triple-split ring resonator are insensitive to different polarized waves and show strong resonant frequency dips near 433 and 444 GHz, respectively. The results of this work suggest new opportunities for the investigation and design of polarization-dependent terahertz devices based on split ring resonators. (paper)

Efficient Homodifunctional Bimolecular Ring-Closure Method for Cyclic Polymers by Combining RAFT and Self-Accelerating Click Reaction.

Science.gov (United States)

Qu, Lin; Sun, Peng; Wu, Ying; Zhang, Ke; Liu, Zhengping

2017-08-01

An efficient metal-free homodifunctional bimolecular ring-closure method is developed for the formation of cyclic polymers by combining reversible addition-fragmentation chain transfer (RAFT) polymerization and self-accelerating click reaction. In this approach, α,ω-homodifunctional linear polymers with azide terminals are prepared by RAFT polymerization and postmodification of polymer chain end groups. By virtue of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DBA) as small linkers, well-defined cyclic polymers are then prepared using the self-accelerating double strain-promoted azide-alkyne click (DSPAAC) reaction to ring-close the azide end-functionalized homodifunctional linear polymer precursors. Due to the self-accelerating property of DSPAAC ring-closing reaction, this novel method eliminates the requirement of equimolar amounts of telechelic polymers and small linkers in traditional bimolecular ring-closure methods. It facilitates this method to efficiently and conveniently produce varied pure cyclic polymers by employing an excess molar amount of DBA small linkers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Precision ring rolling technique and application in high-performance bearing manufacturing

Directory of Open Access Journals (Sweden)

Hua Lin

2015-01-01

Full Text Available High-performance bearing has significant application in many important industry fields, like automobile, precision machine tool, wind power, etc. Precision ring rolling is an advanced rotary forming technique to manufacture high-performance seamless bearing ring thus can improve the working life of bearing. In this paper, three kinds of precision ring rolling techniques adapt to different dimensional ranges of bearings are introduced, which are cold ring rolling for small-scale bearing, hot radial ring rolling for medium-scale bearing and hot radial-axial ring rolling for large-scale bearing. The forming principles, technological features and forming equipments for three kinds of precision ring rolling techniques are summarized, the technological development and industrial application in China are introduced, and the main technological development trend is described.

Design studies for the electron storage ring EUTERPE

Energy Technology Data Exchange (ETDEWEB)

Boling, Xi

1995-05-18

The 400 MeV electron storage ring EUTERPE is under construction at Eindhoven University of Technology. The ring is to be used as an experimental tool for accelerator physics studies and synchroton radiation applications. The main task of the current research work is the electron optical design of the ring. Lattice design is a basis for machine design as a whole. Design aspects regarding the basic lattice, based on single particle dynamics, include determination of the equilibrium beam size and bunch length, design of achromatic bending sections, selection of tune values, correction of chromaticity, and minimization of the natural emittance in the ring. The basic lattice designed for the EUTERPE ring has a high flexibility so that different electron optical modes can be realized easily. In low energy storage rings with a high beam current, collective effects can cause a significant change in the bunch length, the transverse emittance and the beam lifetime. In order to ensure a good optical performance for the ring, the choice of suitable parameters concerning the vacuum and RF system are essential as far as collective effects are concerned. An estimation of the collective effects in the ring is given. The injector for EUTERPE is a 75 MeV racetrack microtron which is injected from a 10 MeV linac. In order to get sufficient beam current in the ring, a special procedure of continuous injection with an adjustable locally shifted closed orbit has been presented. Details of the injection procedure and numerical simulations are given. (orig./HSI).

Design studies for the electron storage ring EUTERPE

International Nuclear Information System (INIS)

Xi Boling.

1995-01-01

The 400 MeV electron storage ring EUTERPE is under construction at Eindhoven University of Technology. The ring is to be used as an experimental tool for accelerator physics studies and synchroton radiation applications. The main task of the current research work is the electron optical design of the ring. Lattice design is a basis for machine design as a whole. Design aspects regarding the basic lattice, based on single particle dynamics, include determination of the equilibrium beam size and bunch length, design of achromatic bending sections, selection of tune values, correction of chromaticity, and minimization of the natural emittance in the ring. The basic lattice designed for the EUTERPE ring has a high flexibility so that different electron optical modes can be realized easily. In low energy storage rings with a high beam current, collective effects can cause a significant change in the bunch length, the transverse emittance and the beam lifetime. In order to ensure a good optical performance for the ring, the choice of suitable parameters concerning the vacuum and RF system are essential as far as collective effects are concerned. An estimation of the collective effects in the ring is given. The injector for EUTERPE is a 75 MeV racetrack microtron which is injected from a 10 MeV linac. In order to get sufficient beam current in the ring, a special procedure of continuous injection with an adjustable locally shifted closed orbit has been presented. Details of the injection procedure and numerical simulations are given. (orig./HSI)

Comparison of disposable sutureless silicone ring and traditional metal ring in 23-gauge vitrectomy combined with cataract surgery

Directory of Open Access Journals (Sweden)

Li X-R

2011-06-01

Full Text Available Jian-Guo Wu, Rui-Hua Wei, Ai-Hua Liu, Xiao-Xu Zhou, Guo-Ling Sun, Xiao-Rong LiTianjin Medical University Eye Center, Tianjin, ChinaBackground: The purpose of this prospective, interventional, comparative case series was to evaluate the efficiency and feasibility of a disposable sutureless silicone lens ring for corneal contact lens stabilization during combined 23-gauge vitrectomy and cataract surgery.Methods: We developed a ring consisting of a single silicone component with three footplates along the ring margin to fit cannulae for holding conventional contact lenses. Thirty eyes from 30 patients with cataract and vitreoretinal disease were included, and divided into two matched groups according to disease type and ring used. In Group A, we used a 23-gauge transconjunctival vitrectomy system and a disposable sutureless silicone lens ring (n = 15. In Group B, we used a 23-gauge transconjunctival vitrectomy system and a conventional metal lens ring (n = 15. The main outcome measures were: time required for vitrectomy preparation, rate of intraoperative corneal limbus bleeding, and limbus scar rate at the final follow-up visit.Results: Thirty cases were successfully completed. The average vitrectomy preparation time was less in Group A than in Group B (P < 0.01, and the average preparation time saved was 3.94 minutes. None of the Group A patients had intraoperative bleeding or postoperative scarring, whereas all 15 Group B cases had bleeding and five had scarring. There was a statistically significant difference between Group A and Group B for these complications (P ≤ 0.05.Conclusion: This report demonstrates the advantages of using a sutureless silicone ring during combined 23-gauge vitrectomy and cataract surgery. Using this method could allow extra time for the surgeon to pay more attention to complex vitreoretinal procedures.Keywords: pars plana vitrectomy, contact lens, silicone ring, cataract surgery

RINGED ACCRETION DISKS: EQUILIBRIUM CONFIGURATIONS

Energy Technology Data Exchange (ETDEWEB)

Pugliese, D.; Stuchlík, Z., E-mail: d.pugliese.physics@gmail.com, E-mail: zdenek.stuchlik@physics.cz [Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo náměstí 13, CZ-74601 Opava (Czech Republic)

2015-12-15

We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.

Stirling engine piston ring

Science.gov (United States)

Howarth, Roy B.

1983-01-01

A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

Physics of quantum rings

International Nuclear Information System (INIS)

Fomin, Vladimir M.

2014-01-01

Presents the new class of materials of quantum rings. Provides an elemental basis for low-cost high-performance devices promising for electronics, optoelectronics, spintronics and quantum information processing. Explains the physical properties of quantum rings to cover a gap in scientific literature. Presents the application of most advanced nanoengineering and nanocharacterization techniques. This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is possible on the basis of modern characterization methods of nanostructures, such as Scanning Tunneling Microscopy. A high level of complexity is demonstrated to be needed for a dedicated theoretical model to adequately represent the specific features of quantum rings. The findings presented in this book contribute to develop low-cost high-performance electronic, spintronic, optoelectronic and information processing devices based on quantum rings.

How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings?

Science.gov (United States)

Mäthger, Lydia M; Bell, George R R; Kuzirian, Alan M; Allen, Justine J; Hanlon, Roger T

2012-11-01

The blue-ringed octopus (Hapalochlaena lunulata), one of the world's most venomous animals, has long captivated and endangered a large audience: children playing at the beach, divers turning over rocks, and biologists researching neurotoxins. These small animals spend much of their time in hiding, showing effective camouflage patterns. When disturbed, the octopus will flash around 60 iridescent blue rings and, when strongly harassed, bite and deliver a neurotoxin that can kill a human. Here, we describe the flashing mechanism and optical properties of these rings. The rings contain physiologically inert multilayer reflectors, arranged to reflect blue-green light in a broad viewing direction. Dark pigmented chromatophores are found beneath and around each ring to enhance contrast. No chromatophores are above the ring; this is unusual for cephalopods, which typically use chromatophores to cover or spectrally modify iridescence. The fast flashes are achieved using muscles under direct neural control. The ring is hidden by contraction of muscles above the iridophores; relaxation of these muscles and contraction of muscles outside the ring expose the iridescence. This mechanism of producing iridescent signals has not previously been reported in cephalopods and we suggest that it is an exceptionally effective way to create a fast and conspicuous warning display.

Acceptability of the vaginal contraceptive ring among adolescent women.

Science.gov (United States)

Terrell, Lekeisha R; Tanner, Amanda E; Hensel, Devon J; Blythe, Margaret J; Fortenberry, J Dennis

2011-08-01

Although underutilized, the vaginal contraceptive ring has several advantages over other contraceptive methods that could benefit adolescents. We examined factors that may influence willingness to try the vaginal ring including: sexual and contraceptive history, genital comfort, and vaginal ring characteristics. Cross sectional Midwestern adolescent health clinics Adolescent women (N = 200; 14-18 years; 89% African-American) INTERVENTIONS/MAIN OUTCOME MEASURES: All participants received education about the vaginal ring and viewed pictures demonstrating insertion; they then completed a visual/audio computer-assisted self interview. The primary outcome variable, willingness to try the vaginal ring, was a single Likert-scale item. Over half the participants reported knowledge of the vaginal ring with healthcare providers identified as the most important source of contraceptive information. Comfort with one's genitals, insertion and removal, using alternative methods of insertion, and knowing positive method characteristics were significantly associated with willingness to try the vaginal ring. A decreased willingness to try the vaginal ring was related to concerns of the ring getting lost inside or falling out of the vagina. Willingness to try the ring was associated with positive feelings about genitals (e.g., comfort with appearance, hygiene, function). Thus, to increase willingness to try the vaginal ring among adolescents, providers should make it common practice to discuss basic female reproductive anatomy, raise awareness about female genital health and address concerns about their genitals. Providers can offer alternative insertion techniques (e.g., gloves) to make use more accessible. These strategies may increase vaginal ring use among adolescents. 2011 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

α-Skew π-McCoy Rings

Directory of Open Access Journals (Sweden)

Areej M. Abduldaim

2013-01-01

Full Text Available As a generalization of α-skew McCoy rings, we introduce the concept of α-skew π-McCoy rings, and we study the relationships with another two new generalizations, α-skew π1-McCoy rings and α-skew π2-McCoy rings, observing the relations with α-skew McCoy rings, π-McCoy rings, α-skew Armendariz rings, π-regular rings, and other kinds of rings. Also, we investigate conditions such that α-skew π1-McCoy rings imply α-skew π-McCoy rings and α-skew π2-McCoy rings. We show that in the case where R is a nonreduced ring, if R is 2-primal, then R is an α-skew π-McCoy ring. And, let R be a weak (α,δ-compatible ring; if R is an α-skew π1-McCoy ring, then R is α-skew π2-McCoy.

Split-Ring Springback Simulations with the Non-associated Flow Rule and Evolutionary Elastic-Plasticity Models

Science.gov (United States)

Lee, K. J.; Choi, Y.; Choi, H. J.; Lee, J. Y.; Lee, M. G.

2018-06-01

Finite element simulations and experiments for the split-ring test were conducted to investigate the effect of anisotropic constitutive models on the predictive capability of sheet springback. As an alternative to the commonly employed associated flow rule, a non-associated flow rule for Hill1948 yield function was implemented in the simulations. Moreover, the evolution of anisotropy with plastic deformation was efficiently modeled by identifying equivalent plastic strain-dependent anisotropic coefficients. Comparative study with different yield surfaces and elasticity models showed that the split-ring springback could be best predicted when the anisotropy in both the R value and yield stress, their evolution and variable apparent elastic modulus were taken into account in the simulations. Detailed analyses based on deformation paths superimposed on the anisotropic yield functions predicted by different constitutive models were provided to understand the complex springback response in the split-ring test.

Some notes on the rings with sacred inscriptions from Pannonia

Directory of Open Access Journals (Sweden)

András Szabó

2015-02-01

Full Text Available More than a hundred rings bearing inscriptions are known from the territory of Roman Pannonia. Among these close to 30 artefacts can be regarded as rings displaying inscriptions of religious significance. Besides the Silvanus-rings, well-known to the archaeological research, some new groups of rings featuring sacred inscriptions can be distinguished according to the dedications. The aim of this paper is to analyse these objects and their religious backgrounds with the help of some archaeological, epigraphical and literary sources and to point out some of the questionable observations of the earlier research.

Crack initiation under generalized plane strain conditions

International Nuclear Information System (INIS)

Shum, D.K.M.; Merkle, J.G.

1991-01-01

A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab

VUV optical ring resonator for Duke storage ring free electron laser

Energy Technology Data Exchange (ETDEWEB)

Park, S.H.; Litvinenko, V.N.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)] [and others

1995-12-31

The conceptual design of the multifaceted-mirror ring resonator for Duke storage ring VUV FEL is presented. The expected performance of the OK-4 FEL with ring resonator is described. We discuss in this paper our plans to study reflectivity of VUV mirrors and their resistivity to soft X-ray spontaneous radiation from OK-4 undulator.

The formation mechanisms and optical characteristics of GaSb quantum rings

International Nuclear Information System (INIS)

Lin, Wei-Hsun; Pao, Chun-Wei; Wang, Kai-Wei; Liao, Yu-An; Lin, Shih-Yen

2013-01-01

The growth mechanisms and optical characteristics of GaSb quantum rings (QRs) are investigated. Although As-for-Sb exchange is the mechanism responsible for the dot-to-ring transition, significant height difference between GaSb quantum dots (QDs) and QRs in a dot/ring mixture sample suggests that the dot-to-ring transition is not a spontaneous procedure. Instead, it is a rapid transition procedure as long as it initiates. A model is established to explain this phenomenon. Larger ring inner diameters and heights of the sample with longer post Sb soaking time suggest that As-for-Sb exchange takes places in both vertical and lateral directions. The decreasing ring densities, enlarged ring inner/outer diameters and eventually flat GaSb surfaces observed with increasing growth temperatures are resulted from enhanced adatom migration and As-for-Sb exchange with increasing growth temperatures

Ring distributions leading to species formation: a global topographic analysis of geographic barriers associated with ring species.

Science.gov (United States)

Monahan, William B; Pereira, Ricardo J; Wake, David B

2012-03-12

In the mid 20th century, Ernst Mayr and Theodosius Dobzhansky championed the significance of circular overlaps or ring species as the perfect demonstration of speciation, yet in the over 50 years since, only a handful of such taxa are known. We developed a topographic model to evaluate whether the geographic barriers that favor processes leading to ring species are common or rare, and to predict where other candidate ring barriers might be found. Of the 952,147 geographic barriers identified on the planet, only about 1% are topographically similar to barriers associated with known ring taxa, with most of the likely candidates occurring in under-studied parts of the world (for example, marine environments, tropical latitudes). Predicted barriers separate into two distinct categories: (i) single cohesive barriers (barriers - formed by groups of barriers (each 184,000 to 1.7 million km2) in close geographic proximity (totaling 1.9 to 2.3 million km2) - associated with taxa that differentiate at larger spatial scales (birds: Phylloscopus trochiloides and Larus (sp. argentatus and fuscus)). When evaluated globally, we find a large number of cohesive barriers that are topographically similar to those associated with known ring taxa. Yet, compared to cohesive barriers, an order of magnitude fewer composite barriers are similar to those that favor ring divergence in species with higher dispersal. While these findings confirm that the topographic conditions that favor evolutionary processes leading to ring speciation are, in fact, rare, they also suggest that many understudied natural systems could provide valuable demonstrations of continuous divergence towards the formation of new species. Distinct advantages of the model are that it (i) requires no a priori information on the relative importance of features that define barriers, (ii) can be replicated using any kind of continuously distributed environmental variable, and (iii) generates spatially explicit hypotheses of

[Clinical significance of infection with cag A and vac A positive Helicobacter pylori strains].

Science.gov (United States)

Sokić-Milutinović, Aleksandra; Todorović, Vera; Milosavljević, Tomica

2004-01-01

Clinical relevance of infection with different Helicobacter pylori strains was reviewed in this paper. Helicobacter pylori (H. pylori) infection plays a role in pathogenesis of chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. Extragastric manifestations of H. pylori infection most probably include acne rosacea and chronic urticaria, while the importance of H. pylori infection for pathogenesis of growth retardation in children, iron deficiency anemia, coronary heart disease, stroke and idiopathic thrombocytopenic purpura remains vague. The expression of two H. pylori proteins, cytotoxin associated protein (cag A) and vacuolization cytotoxin (vac A) is considered to be related with pathogenicity of the bacterium. It is clear that presence of cag A+ strains is important for development of peptic ulcer; nevertheless, it is also protective against esophageal reflux disease. On the other hand, cag A+ strains are common in gastric adenocarcinoma and MALT lymphoma patients, but it seems that certain subtypes of vac A cytotoxin are more important risk factors. Infection with cag A+ strains is more common in patients with acne rosacea, stroke and coronary heart disease.

Clinical significance of infection with cag A and vac A positive helicobacter pylori strains

Directory of Open Access Journals (Sweden)

Sokić-Milutinović Aleksandra

2004-01-01

Full Text Available Clinical relevance of infection with different Helicobacter pylori strains was reviewed in this paper. Helicobacter pylori (H. pylori infection plays a role in pathogenesis of chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. Extragastric manifestations of H. pylori infection most probably include acne rosacea and chronic urticaria, while the importance of H. pylori infection for pathogenesis of growth retardation in children, iron deficiency anemia, coronary heart disease, stroke and idiopathic thrombocytopenic purpura remains vague. The expression of two H. pylori proteins, cytotoxin associated protein (cag A and vacuolization cytotoxin (vac A is considered to be related with pathogenicity of the bacterium. It is clear that presence of cag A+ strains is important for development of peptic ulcer; nevertheless, it is also protective against esophageal reflux disease. On the other hand, cag A+ strains are common in gastric adenocarcinoma and MALT lymphoma patients, but it seems that certain subtypes of vac A cytotoxin are more important risk factors. Infection with cag A+ strains is more common in patients with acne rosacea, stroke and coronary heart disease.

Interaction Region Design for a Ring-Ring LHeC

CERN Document Server

Thompson, L N S; Bernard, N R; Fitterer, M; Holzer, B; Klein, M; Kostka, P

2011-01-01

tively low energy and moderately high intensity provides high luminosity TeV-scale e-p collisions at one of the LHC interaction points, running simultaneously with existing experiments. Two designs are studied; an electron ring situated in the LHC tunnel, and an electron linac. The focus of this paper is on the ring design. Designing an e-p machine presents interesting accelerator physics and design challenges, particularly when considering the interaction region. These include coupled optics, beam separation and unconventional mini-beta focusing schemes. Designs are constrained by an array of interdependent factors, including beam-beam interaction, detector dimensions and acceptance, luminosity and synchrotron radiation. Methods of addressing these complex issues are discussed. The current designs for the LHeC Ring-Ring interaction region and long straight section are presented and discussed, in the context of the project goals and design challenges encountered. Future developments and work are also discusse...

The nonlinear evolution of ring dark solitons in Bose-Einstein condensates

International Nuclear Information System (INIS)

Xue Jukui

2004-01-01

The dynamics of the ring dark soliton in a Bose-Einstein condensate (BEC) with thin disc-shaped potential is investigated analytically and numerically. Analytical investigation shows that the ring dark soliton in the radial non-symmetric cylindrical BEC is governed by a cylindrical Kadomtsev-Petviashvili equation, while the ring dark soliton in the radial symmetric cylindrical BEC is governed by a cylindrical Korteweg-de Vries equation. The reduction to the cylindrical KP or KdV equation may be useful to understand the dynamics of a ring dark soliton. The numerical results show that the evolution properties and the snaking of a ring dark soliton are modified significantly by the trapping

Improving the accuracy of Laplacian estimation with novel multipolar concentric ring electrodes

Science.gov (United States)

Ding, Quan; Besio, Walter G.

2015-01-01

Conventional electroencephalography with disc electrodes has major drawbacks including poor spatial resolution, selectivity and low signal-to-noise ratio that are critically limiting its use. Concentric ring electrodes, consisting of several elements including the central disc and a number of concentric rings, are a promising alternative with potential to improve all of the aforementioned aspects significantly. In our previous work, the tripolar concentric ring electrode was successfully used in a wide range of applications demonstrating its superiority to conventional disc electrode, in particular, in accuracy of Laplacian estimation. This paper takes the next step toward further improving the Laplacian estimation with novel multipolar concentric ring electrodes by completing and validating a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2 that allows cancellation of all the truncation terms up to the order of 2n. An explicit formula based on inversion of a square Vandermonde matrix is derived to make computation of multipolar Laplacian more efficient. To confirm the analytic result of the accuracy of Laplacian estimate increasing with the increase of n and to assess the significance of this gain in accuracy for practical applications finite element method model analysis has been performed. Multipolar concentric ring electrode configurations with n ranging from 1 ring (bipolar electrode configuration) to 6 rings (septapolar electrode configuration) were directly compared and obtained results suggest the significance of the increase in Laplacian accuracy caused by increase of n. PMID:26693200

Uniquely Strongly Clean Group Rings

Institute of Scientific and Technical Information of China (English)

WANG XIU-LAN

2012-01-01

A ring R is called clean if every element is the sum of an idempotent and a unit,and R is called uniquely strongly clean (USC for short) if every element is uniquely the sum of an idempotent and a unit that commute.In this article,some conditions on a ring R and a group G such that RG is clean are given.It is also shown that if G is a locally finite group,then the group ring RG is USC if and only if R is USC,and G is a 2-group.The left uniquely exchange group ring,as a middle ring of the uniquely clean ring and the USC ring,does not possess this property,and so does the uniquely exchange group ring.

Influence of ring growth rate on damage development in hot ring rolling

NARCIS (Netherlands)

Wang, C.; Geijselaers, H. J.M.; Omerspahic, E.; Recina, V.; van den Boogaard, A. H.

2015-01-01

As an incremental forming process of bulk metal, ring rolling provides a cost effective process route to manufacture seamless rings. In the production of hot rolled rings, defects such as porosity can sometimes be found in high alloyed steel, manufactured from ingots having macro-segregation. For

Ring rotational speed trend analysis by FEM approach in a Ring Rolling process

Science.gov (United States)

Allegri, G.; Giorleo, L.; Ceretti, E.

2018-05-01

Ring Rolling is an advanced local incremental forming technology to fabricate directly precise seamless ring-shape parts with various dimensions and materials. In this process two different deformations occur in order to reduce the width and the height of a preform hollow ring; as results a diameter expansion is obtained. In order to guarantee a uniform deformation, the preform is forced toward the Driver Roll whose aim is to transmit the rotation to the ring. The ring rotational speed selection is fundamental because the higher is the speed the higher will be the axial symmetry of the deformation process. However, it is important to underline that the rotational speed will affect not only the final ring geometry but also the loads and energy needed to produce it. Despite this importance in industrial environment, usually, a constant value for the Driver Roll angular velocity is set so to result in a decreasing trend law for the ring rotational speed. The main risk due to this approach is not fulfilling the axial symmetric constrain (due to the diameter expansion) and to generate a high localized ring section deformation. In order to improve the knowledge about this topic in the present paper three different ring rotational speed trends (constant, linearly increasing and linearly decreasing) were investigated by FEM approach. Results were compared in terms of geometrical and dimensional analysis, loads and energies required.

Ring correlations in random networks.

Science.gov (United States)

Sadjadi, Mahdi; Thorpe, M F

2016-12-01

We examine the correlations between rings in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening rings), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central ring. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between ring centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between rings decaying away when two rings are more than about three rings apart.

Experimental investigation of strain, damage and failure of hydrided zircaloy-4 with various hydride orientations

International Nuclear Information System (INIS)

Racine, A; Catherine, C.S.; Cappelaere, C.; Bornert, M.; Caldemaison, D.

2005-01-01

This experimental investigation is devoted to the influence of the orientation of hydrides on the mechanical response of Zircaloy-4. Ring tensile tests are performed on unirradiated CWSR Zircaloy-4, charged with about 200 or 500wppm hydrogen. Hydrides are oriented either parallel ('tangential'), or perpendicular ('radial') to the circumferential tensile direction. Tangential hydrides are usually observed in cladding tubes, however, hydrides can be reoriented after cooling under stress to become radial and then trigger brittle behavior. In this investigation, we perform, 'macroscopic' or SEM in-situ tensile tests on smooth rings, at room temperature. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. The results lead to the following conclusions: neither the tensile stress-strain response nor the strain modes are affected by hydrogen content or hydride orientation, but the failure modes are. Indeed, only 200wppm radial hydrides embrittle Zy-4: sample fails in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases samples reach at least 750 MPa before failure, with ductile or brittle mode. (authors)

Development of Cone Wedge Ring Expansion Test to Evaluate Mechanical Properties of Clad Tubing Structure

Energy Technology Data Exchange (ETDEWEB)

Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-10-01

To determine the hoop tensile properties of irradiated fuel cladding in a hot cell, a cone wedge ring expansion test method was developed. A four-piece wedge insert was designed with tapered angles matched to the cone shape of a loading piston. The ring specimen was expanded in the radial direction by the lateral expansion of the wedges under the downward movement of the piston. The advantages of the proposed method are that implementation of the test setup in a hot cell is simple and easy, and that it enables a direct strain measurement of the test specimen from the piston’s vertical displacement soon after the wedge-clad contact resistance is initiated.

Alpha - Skew Pi - Armendariz Rings

Directory of Open Access Journals (Sweden)

Areej M Abduldaim

2018-03-01

Full Text Available In this article we introduce a new concept called Alpha-skew Pi-Armendariz rings (Alpha - S Pi - ARas a generalization of the notion of Alpha-skew Armendariz rings.Another important goal behind studying this class of rings is to employ it in order to design a modern algorithm of an identification scheme according to the evolution of using modern algebra in the applications of the field of cryptography.We investigate general properties of this concept and give examples for illustration. Furthermore, this paperstudy the relationship between this concept and some previous notions related to Alpha-skew Armendariz rings. It clearly presents that every weak Alpha-skew Armendariz ring is Alpha-skew Pi-Armendariz (Alpha-S Pi-AR. Also, thisarticle showsthat the concepts of Alpha-skew Armendariz rings and Alpha-skew Pi- Armendariz rings are equivalent in case R is 2-primal and semiprime ring.Moreover, this paper proves for a semicommutative Alpha-compatible ringR that if R[x;Alpha] is nil-Armendariz, thenR is an Alpha-S Pi-AR. In addition, if R is an Alpha - S Pi -AR, 2-primal and semiprime ring, then N(R[x;Alpha]=N(R[x;Alpha]. Finally, we look forwardthat Alpha-skew Pi-Armendariz rings (Alpha-S Pi-ARbe more effect (due to their properties in the field of cryptography than Pi-Armendariz rings, weak Armendariz rings and others.For these properties and characterizations of the introduced concept Alpha-S Pi-AR, we aspire to design a novel algorithm of an identification scheme.

Physiological Responses during Cycling With Oval Chainrings (Q-Ring and Circular Chainrings

Directory of Open Access Journals (Sweden)

Alfredo Cordova

2014-06-01

Full Text Available The aim of this study was to compare the physiological responses of cyclists using round (C-ring or oval (Q-ring chainrings during an incremental test until exhaustion. Following a randomized design, fourteen male elite cyclists [age (mean ± SD: 21.1 ± 2.1 yr; VO2max: 78.5 ± 5.3 mL·kg-1min-1] performed two incremental maximal tests separated by 48 h (one with C-rings, the other with Q-rings. Starting at 100 W, the workload was increased by 25 W every 3 min until volitional exhaustion. Maximal heart rate, power output and oxygen consumption were compared. Blood lactate was monitored throughout the test. After the incremental test, 4 intermittent 20-s maximal sprints with a 60-s recovery period in between were performed. Maximal isometric voluntary contractions were performed at rest and immediately after each 20-s maximal sprint, and the force and EMG RMS amplitude were recorded from the vastus medialis and vastus lateralis muscles. For the incremental exercise test, no significant differences were found in the maximal power output (P=0.12, oxygen consumption (P=0.39, and heart rate (P=0.32 between Q-rings and C-rings. Throughout the incremental test, lactate levels were comparable when using both the C-rings and Q-rings (P=0.47. During the short sprints, power output was 2.5–6.5% greater for Q-rings than for C-rings (P=0.22. The decline in EMG RMS amplitude observed during the incremental tests was comparable for Q-rings and C-rings (0.42. These findings indicate that the oval chainring design, presented here as “Q-rings”, did not significantly influence the physiological response to an incremental exercise test as compared to a conventional chainring.

Heat transfer behaviors in round tube with conical ring inserts

International Nuclear Information System (INIS)

Promvonge, P.

2008-01-01

To increase convection heat transfer in a uniform heat flux tube by a passive method, several conical rings used as turbulators are mounted over the test tube. The effects of the conical ring turbulator inserts on the heat transfer rate and friction factor are experimentally investigated in the present work. Conical rings with three different diameter ratios of the ring to tube diameter (d/D = 0.5, 0.6, 0.7) are introduced in the tests, and for each ratio, the rings are placed with three different arrangements (converging conical ring, referred to as CR array, diverging conical ring, DR array and converging-diverging conical ring, CDR array). In the experiment, cold air at ambient condition for Reynolds numbers in a range of 6000-26,000 is passed through the uniform heat flux circular tube. It is found that the ring to tube diameter ratio and the ring arrays provide a significant effect on the thermal performance of the test tube. The experimental results demonstrate that the use of conical ring inserts leads to a higher heat transfer rate than that of the plain surface tube, and the DR array yields a better heat transfer than the others. The results are also correlated in the form of Nusselt number as a function of Reynolds number, Prandtl number and diameter ratio. An augmentation of up to 197%, 333%, and 237% in Nusselt number is obtained in the turbulent flow for the CR, DR and CDR arrays, respectively, although the effect of using the conical ring causes a substantial increase in friction factor

Ring diagrams and phase transitions

International Nuclear Information System (INIS)

Takahashi, K.

1986-01-01

Ring diagrams at finite temperatures carry most infrared-singular parts among Feynman diagrams. Their effect to effective potentials are in general so significant that one must incorporate them as well as 1-loop diagrams. The author expresses these circumstances in some examples of supercooled phase transitions

The Dynamical History of Chariklo and Its Rings

Energy Technology Data Exchange (ETDEWEB)

Wood, Jeremy [Hazard Community and Technical College, Community College Drive, Hazard, KY 41701 (United States); Horner, Jonti; Marsden, Stephen C. [Computational Engineering and Science Research Centre, University of Southern Queensland, West Street, Toowoomba, QLD 4350 (Australia); Hinse, Tobias C., E-mail: jeremy.wood@kctcs.edu [Korea Astronomy and Space Science Institute, 776 Daedukdae-ro, Yuseong-gu, Daejeon 305-348 (Korea, Republic of)

2017-06-01

Chariklo is the only small solar system body confirmed to have rings. Given the instability of its orbit, the presence of rings is surprising, and their origin remains poorly understood. In this work, we study the dynamical history of the Chariklo system by integrating almost 36,000 Chariklo clones backward in time for 1 Gyr under the influence of the Sun and the four giant planets. By recording all close encounters between the clones and planets, we investigate the likelihood that Chariklo’s rings could have survived since its capture to the Centaur population. Our results reveal that Chariklo’s orbit occupies a region of stable chaos, resulting in its orbit being marginally more stable than those of the other Centaurs. Despite this, we find that it was most likely captured to the Centaur population within the last 20 Myr, and that its orbital evolution has been continually punctuated by regular close encounters with the giant planets. The great majority (>99%) of those encounters within 1 Hill radius of the planet have only a small effect on the rings. We conclude that close encounters with giant planets have not had a significant effect on the ring structure. Encounters within the Roche limit of the giant planets are rare, making ring creation through tidal disruption unlikely.

Plasma-ring, fast-opening switch

International Nuclear Information System (INIS)

Hartman, C.W.; Eddleman, J.; Hammer, J.H.

1986-01-01

The authors discuss a fast-opening switch concept based on magnetically confined plasma rings, PROS (for Plasma Ring Opening Switch). In PROS, the plasma ring, confined by Bθ /sub and B/poloidal /sub fields of a compact torus, provide a low mass, localized conduction path between coaxial electrodes. To operate the switch, driver current is passed across the electrodes through the ring, storing inductive energy in external inductance and between the electrodes on the driver side of the ring. The ring is accelerated away from the driver by the field of the driver current and passes over a load gap transferring the current to the load. The authors distinguish two configurations in PROS, straight PROS where the electrodes are coaxial cylinders, and cone PROS with conical electrodes. In straight PROS ring acceleration takes place during the inductive store period as in foil switches, but with the localized ring providing the current path. Increased performance is predicted for the cone PROS (see figure) which employs compression of the ring in the cone during the inductive store period. Here, the B/θ /sub field of the driver forces the ring towards the apex of the cone but the force is in near balance with the opposing component of the radial equilibrium force of the ring along the cone. As a result, the ring undergoes a slow, quasistatic compression limited only by resistive decay of the ring field. Slow compression allows inductive storage with low-power drivers (homopoloar, magneto cumulative generators, high C-low V capacitor banks, etc.). Near the apex of the cone, near peak compression, the ring is allowed to enter a straight coaxial section where, because of low-mass, it rapidly accelerates to high velocity and crosses the load gap

Fusion Rings for Quantum Groups

DEFF Research Database (Denmark)

Andersen, Henning Haahr; Stroppel, Catharina

2014-01-01

We study the fusion rings of tilting modules for a quantum group at a root of unity modulo the tensor ideal of negligible tilting modules. We identify them in type A with the combinatorial rings from Korff, C., Stroppel, C.: The sl(ˆn)k-WZNW fusion ring: a combinato-rial construction...... and a realisation as quotient of quantum cohomology. Adv. Math. 225(1), 200–268, (2010) and give a similar description of the sp2n-fusion ring in terms of non-commutative symmetric functions. Moreover we give a presentation of all fusion rings in classical types as quotients of polynomial rings. Finally we also...... compute the fusion rings for type G2....

The LSU Electron Storage Ring, the first commercially-built storage ring

International Nuclear Information System (INIS)

Sah, R.

1990-01-01

The Brobeck Division of Maxwell Laboratories, Inc., is building the first industrially-produced storage ring. It will be located at Louisiana State University (LSU) at the Center for Advanced Microstructures and Devices (CAMD) in Baton Rouge. The purpose of this electron storage ring is to provide intense beams of x-rays to advance the state-of-the-art in lithography and to permit research in a broad area. This facility consists of a 1.2 GeV, 400 mA electron storage ring with a 200 MeV linac injector. The magnet lattice is a Chasman-Green design (double-bend achromat), and the ring circumference is 55.2 meters. There are four 3.0 meter, dispersion-free straight sections, one for injection, one for the 500 MHz RF cavity, and two for possible future insertion devices. The storge ring construction project is in the detailed-design stage, and many systems are in the initial stages of fabrication. 4 figs., 1 tab

Erbium-doped fiber ring laser with SMS modal interferometer for hydrogen sensing

Science.gov (United States)

Zhang, Ya-nan; Zhang, Lebin; Han, Bo; Peng, Huijie; Zhou, Tianmin; Lv, Ri-qing

2018-06-01

A hydrogen sensor based on erbium-doped fiber ring laser with modal interferometer is proposed. A single mode-multimode-single mode (SMS) modal interferometer structure coated with Pd/WO3 film is used as the sensing head, due to that it is easy to be fabricated and low cost. The sensing structure is inserted into an erbium-doped fiber ring laser in order to solve the problem of spectral confusion and improve the detection limit of the hydrogen sensor based on the SMS modal interferometer. The SMS sensing structure is acted as a fiber band-pass filter. When hydrogen concentration around the sensor is changed, it will induce the refractive index and strain variations of the Pd/WO3 film, and then shift the resonant spectrum of the SMS modal interferometer as well as the laser wavelength of the fiber ring laser. Therefore, the hydrogen concentration can be measured by monitoring the wavelength shift of the laser, which has high intensity and narrow full width half maximum. Experimental results demonstrate that the sensor has high sensitivity of 1.23 nm/%, low detection limit of 0.017%, good stability and excellent repeatability.

Fusion rings and fusion ideals

DEFF Research Database (Denmark)

Andersen, Troels Bak

by the so-called fusion ideals. The fusion rings of Wess-Zumino-Witten models have been widely studied and are well understood in terms of precise combinatorial descriptions and explicit generating sets of the fusion ideals. They also appear in another, more general, setting via tilting modules for quantum......This dissertation investigates fusion rings, which are Grothendieck groups of rigid, monoidal, semisimple, abelian categories. Special interest is in rational fusion rings, i.e., fusion rings which admit a finite basis, for as commutative rings they may be presented as quotients of polynomial rings...

A silicone elastomer vaginal ring for HIV prevention containing two microbicides with different mechanisms of action.

Science.gov (United States)

Fetherston, Susan M; Boyd, Peter; McCoy, Clare F; McBride, Marcella C; Edwards, Karen-Leigh; Ampofo, Stephen; Malcolm, R Karl

2013-02-14

Vaginal rings are currently being developed for the long-term (at least 30 days) continuous delivery of microbicides against human immunodeficiency virus (HIV). Research to date has mostly focused on devices containing a single antiretroviral compound, exemplified by the 25mg dapivirine ring currently being evaluated in a Phase III clinical study. However, there is a strong clinical rationale for combining antiretrovirals with different mechanisms of action in a bid to increase breadth of protection and limit the emergence of resistant strains. Here we report the development of a combination antiretroviral silicone elastomer matrix-type vaginal ring for simultaneous controlled release of dapivirine, a non-nucleoside reverse transcriptase inhibitor, and maraviroc, a CCR5-targeted HIV-1 entry inhibitor. Vaginal rings loaded with 25mg dapivirine and various quantities of maraviroc (50-400mg) were manufactured and in vitro release assessed. The 25mg dapivirine and 100mg maraviroc formulation was selected for further study. A 24-month pharmaceutical stability evaluation was conducted, indicating good product stability in terms of in vitro release, content assay, mechanical properties and related substances. This combination ring product has now progressed to Phase I clinical testing. Copyright © 2012 Elsevier B.V. All rights reserved.

Low energy current accumulator for high-energy proton rings

International Nuclear Information System (INIS)

Month, M.

1977-01-01

Building current in high-energy p-p colliding beam machines is most appropriately done in a low-energy (small circumference) current accumulator. Three significant factors favor such a procedure: First, large rings tend to be susceptible to unstable longitudinal density oscillations. These can be avoided by pumping up the beam in the accumulator. When the current stack is injected into the storage ring, potentially harmful instability is essentially neutralized. Second, high-field magnets characteristic of future high energy proton rings are designed with superconducting coils within the iron magnetic shield. This means coil construction and placement errors propagate rapidly within the beam aperture. An intermediate ''stacking ring'' allows the minimum use of the superconducting ring aperture. Finally, the coils are vulnerable to radiation heating and possible magnet quenching. By minimizing beam manipulaion in the superconducting environment and using only the central portion of the beam aperture, coil vulnerability can be put at a minimum

Ring on the hook: placing a ring on a moving and pendulating hook based on visual input

DEFF Research Database (Denmark)

Kjær-Nielsen, Anders; Buch, Anders Glent; Jensen, Andreas Kryger

2011-01-01

Purpose – The purpose of this paper is to describe a robot vision system which put rings on hooks that are moving freely on a conveyor belt. The hook can show a significant swinging which can be well approximated by a pendulum movement. The problem is of large relevance for many industrial...... applications and the challenge is to compute a 3D pose that is sufficiently precise to allow for successful placements of the rings. Design/methodology/approach – This requires a fast and precise tracking and a compensation for latencies connected to the processing of visual information as well as the actual...

Evaluation of ring impedance of the Photon Factory storage ring

International Nuclear Information System (INIS)

Kiuchi, T.; Izawa, M.; Tokumoto, S.; Hori, Y.; Sakanaka, S.; Kobayashi, M.; Kobayakawa, H.

1992-05-01

The loss parameters of the ducts in the Photon Factory (PF) storage ring were evaluated using the wire method and the code TBCI. Both the measurement and the calculation were done for a different bunch length (σ) ranging from 23 to 80 ps. The PF ring impedance was estimated to be |Z/n|=3.2 Ω using the broadband impedance model. The major contribution to the impedance comes from the bellows and the gate valve sections. Improvements of these components will lower the ring impedance by half. (author)

Tree Rings: Timekeepers of the Past.

Science.gov (United States)

Phipps, R. L.; McGowan, J.

One of a series of general interest publications on science issues, this booklet describes the uses of tree rings in historical and biological recordkeeping. Separate sections cover the following topics: dating of tree rings, dating with tree rings, tree ring formation, tree ring identification, sample collections, tree ring cross dating, tree…

Simulation of natural fragmentation of rings cut from warheads

Directory of Open Access Journals (Sweden)

John F. Moxnes

2015-12-01

Full Text Available Natural fragmentation of warheads that detonates causes the casing of the warhead to split into various sized fragments through shear or radial fractures depending on the toughness, density, and grain size of the material. The best known formula for the prediction of the size distribution is the Mott formulae, which is further examined by Grady and Kipp by investigating more carefully the statistical most random way of portioning a given area into a number of entities. We examine the fragmentation behavior of radially expanding steel rings cut from a 25 mm warhead by using an in house smooth particle hydrodynamic (SPH simulation code called REGULUS. Experimental results were compared with numerical results applying varying particle size and stochastic fracture strain. The numerically obtained number of fragments was consistent with experimental results. Increasing expansion velocity of the rings increases the number of fragments. Statistical variation of the material parameters influences the fragment characteristics, especially for low expansion velocities. A least square regression fit to the cumulative number of fragments by applying a generalized Mott distribution shows that the shape parameter is around 4 for the rings, which is in contrast to the Mott distribution with a shape parameter of ½. For initially polar distributed particles, we see signs of a bimodal cumulative fragment distribution. Adding statistical variation in material parameters of the fracture model causes the velocity numerical solutions to become less sensitive to changes in resolution for Cartesian distributed particles.

Ring distributions leading to species formation: a global topographic analysis of geographic barriers associated with ring species

Directory of Open Access Journals (Sweden)

Monahan William B

2012-03-01

Full Text Available Abstract Background In the mid 20th century, Ernst Mayr and Theodosius Dobzhansky championed the significance of circular overlaps or ring species as the perfect demonstration of speciation, yet in the over 50 years since, only a handful of such taxa are known. We developed a topographic model to evaluate whether the geographic barriers that favor processes leading to ring species are common or rare, and to predict where other candidate ring barriers might be found. Results Of the 952,147 geographic barriers identified on the planet, only about 1% are topographically similar to barriers associated with known ring taxa, with most of the likely candidates occurring in under-studied parts of the world (for example, marine environments, tropical latitudes. Predicted barriers separate into two distinct categories: (i single cohesive barriers (2, associated with taxa that differentiate at smaller spatial scales (salamander: Ensatina eschscholtzii; tree: Acacia karroo; and (ii composite barriers - formed by groups of barriers (each 184,000 to 1.7 million km2 in close geographic proximity (totaling 1.9 to 2.3 million km2 - associated with taxa that differentiate at larger spatial scales (birds: Phylloscopus trochiloides and Larus (sp. argentatus and fuscus. When evaluated globally, we find a large number of cohesive barriers that are topographically similar to those associated with known ring taxa. Yet, compared to cohesive barriers, an order of magnitude fewer composite barriers are similar to those that favor ring divergence in species with higher dispersal. Conclusions While these findings confirm that the topographic conditions that favor evolutionary processes leading to ring speciation are, in fact, rare, they also suggest that many understudied natural systems could provide valuable demonstrations of continuous divergence towards the formation of new species. Distinct advantages of the model are that it (i requires no a priori information on the

Introducing Modified Degree 4 Chordal Rings with Two Chord Lengths

DEFF Research Database (Denmark)

Pedersen, Jens Myrup

2007-01-01

In this paper an analysis of modified degree 4 Chordal Rings with two chord lengths named CHRm is presented and compared to similar topologies: Chordal Rings, N2R and modified N2R. Formulas for approximating diameters and average path lengths are provided and verified, and it is shown...... that the distances in CHRm are significantly smaller than in traditional Chordal Rings and N2R, and also smaller than modified N2R for topologies with up to 1500 nodes. Despite the proposed CHRm being of degree 4, and the modified N2R of degree 3, CHRm may be better suited for the optical level of fiber rings, due...

Some Aspects of Ring Theory

CERN Document Server

Herstein, IN

2011-01-01

S. Amitsur: Associative rings with identities.- I.N. Herstein: Topics in ring theory.- N. Jacobson: Representation theory of Jordan algebras.- I. Kaplansky: The theory of homological dimension.- D. Buchsbaum: Complexes in local ring theory.- P.H. Cohn: Two topics in ring theory.- A.W. Goldie: Non-commutative localisation.

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes

Directory of Open Access Journals (Sweden)

Oleksandr Makeyev

2016-06-01

Full Text Available Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1-polar electrode with n rings using the (4n + 1-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2 and quadripolar (n = 3 electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected.

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes

Science.gov (United States)

Makeyev, Oleksandr; Besio, Walter G.

2016-01-01

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected. PMID:27294933

Performance characteristics of CdTe drift ring detector

Science.gov (United States)

Alruhaili, A.; Sellin, P. J.; Lohstroh, A.; Veeramani, P.; Kazemi, S.; Veale, M. C.; Sawhney, K. J. S.; Kachkanov, V.

2014-03-01

CdTe and CdZnTe material is an excellent candidate for the fabrication of high energy X-ray spectroscopic detectors due to their good quantum efficiency and room temperature operation. The main material limitation is associated with the poor charge transport properties of holes. The motivation of this work is to investigate the performance characteristics of a detector fabricated with a drift ring geometry that is insensitive to the transport of holes. The performance of a prototype Ohmic CdTe drift ring detector fabricated by Acrorad with 3 drift rings is reported; measurements include room temperature current voltage characteristics (IV) and spectroscopic performance. The data shows that the energy resolution of the detector is limited by leakage current which is a combination of bulk and surface leakage currents. The energy resolution was studied as a function of incident X-ray position with an X-ray microbeam at the Diamond Light Source. Different ring biasing schemes were investigated and the results show that by increasing the lateral field (i.e. the bias gradient across the rings) the active area, evaluated by the detected count rate, increased significantly.

Radar imaging of Saturn's rings

Science.gov (United States)

Nicholson, Philip D.; French, Richard G.; Campbell, Donald B.; Margot, Jean-Luc; Nolan, Michael C.; Black, Gregory J.; Salo, Heikki J.

2005-09-01

We present delay-Doppler images of Saturn's rings based on radar observations made at Arecibo Observatory between 1999 and 2003, at a wavelength of 12.6 cm and at ring opening angles of 20.1°⩽|B|⩽26.7°. The average radar cross-section of the A ring is ˜77% relative to that of the B ring, while a stringent upper limit of 3% is placed on the cross-section of the C ring and 9% on that of the Cassini Division. These results are consistent with those obtained by Ostro et al. [1982, Icarus 49, 367-381] from radar observations at |B|=21.4°, but provide higher resolution maps of the rings' reflectivity profile. The average cross-section of the A and B rings, normalized by their projected unblocked area, is found to have decreased from 1.25±0.31 to 0.74±0.19 as the rings have opened up, while the circular polarization ratio has increased from 0.64±0.06 to 0.77±0.06. The steep decrease in cross-section is at variance with previous radar measurements [Ostro et al., 1980, Icarus 41, 381-388], and neither this nor the polarization variations are easily understood within the framework of either classical, many-particle-thick or monolayer ring models. One possible explanation involves vertical size segregation in the rings, whereby observations at larger elevation angles which see deeper into the rings preferentially see the larger particles concentrated near the rings' mid-plane. These larger particles may be less reflective and/or rougher and thus more depolarizing than the smaller ones. Images from all four years show a strong m=2 azimuthal asymmetry in the reflectivity of the A ring, with an amplitude of ±20% and minima at longitudes of 67±4° and 247±4° from the sub-Earth point. We attribute the asymmetry to the presence of gravitational wakes in the A ring as invoked by Colombo et al. [1976, Nature 264, 344-345] to explain the similar asymmetry long seen at optical wavelengths. A simple radiative transfer model suggests that the enhancement of the azimuthal

Connections between Star Cluster Populations and Their Host Galaxy Nuclear Rings

Science.gov (United States)

Ma, Chao; de Grijs, Richard; Ho, Luis C.

2018-04-01

Nuclear rings are excellent laboratories for probing diverse phenomena such as the formation and evolution of young massive star clusters and nuclear starbursts, as well as the secular evolution and dynamics of their host galaxies. We have compiled a sample of 17 galaxies with nuclear rings, which are well resolved by high-resolution Hubble and Spitzer Space Telescope imaging. For each nuclear ring, we identified the ring star cluster population, along with their physical properties (ages, masses, and extinction values). We also determined the integrated ring properties, including the average age, total stellar mass, and current star formation rate (SFR). We find that Sb-type galaxies tend to have the highest ring stellar mass fraction with respect to the host galaxy, and this parameter is correlated with the ring’s SFR surface density. The ring SFRs are correlated with their stellar masses, which is reminiscent of the main sequence of star-forming galaxies. There are striking correlations between star-forming properties (i.e., SFR and SFR surface density) and nonaxisymmetric bar parameters, appearing to confirm previous inferences that strongly barred galaxies tend to have lower ring SFRs, although the ring star formation histories turn out to be significantly more complicated. Nuclear rings with higher stellar masses tend to be associated with lower cluster mass fractions, but there is no such relation for the ages of the rings. The two youngest nuclear rings in our sample, NGC 1512 and NGC 4314, which have the most extreme physical properties, represent the young extremity of the nuclear ring age distribution.

Viscosity of ring polymer melts

KAUST Repository

Pasquino, Rossana

2013-10-15

We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

Viscosity of ring polymer melts

KAUST Repository

Pasquino, Rossana; Vasilakopoulos, Thodoris C.; Jeong, Youncheol; Lee, Hyojoon; Rogers, Simon A.; Sakellariou, Georgios; Allgaier, Jü rgen B.; Takano, Atsushi; Brá s, Ana Rita E; Chang, Taihyun; Gooß en, Sebastian; Pyckhout-Hintzen, Wim; Wischnewski, Andreas; Hadjichristidis, Nikolaos; Richter, Dieter R.; Rubinstein, Michael H.; Vlassopoulos, Dimitris

2013-01-01

We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

Strain measurements at high temperatures in a concrete structure representing a cylindrical section of a PCPV with hot liner

International Nuclear Information System (INIS)

Schittenhelm, Ch.

1975-11-01

In an experimental ring, representing an 1 m high section of the Austrian PCPV-Model with hot liner, different types of strain gauges were installed in the insulating concrete and the prestressed concrete. In this ring the thermal conditions were the same as in the PCPV-Model. In this report the results of measurements of the past two years are brought and comparisons with static calculations is attempted. (author)

Numerical analysis on seismic behavior of reinforced concrete beam to concrete filled steel tubular column connections with ring-beam

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yi., E-mail: zhaoyi091218@163.com [School of Civil and Architectural Engineering, Zhongyuan University of Technology,Zhengzhou 450000 (China); Xu, Li. Hua. [School of Civil Engineering, Wuhan University, No.8, Donghu Road, WuHan 430072 (China)

2016-06-08

This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete. The results show that the ultimate capacity of the connections is improved with sectional dimension of the ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete.

Læring og refleksion

DEFF Research Database (Denmark)

Wahlgren, B.; Rattleff, Pernille; Høyrup, S.

State of the art inden for forskning om læring på arbejdspladsen samt gennemgang af læringsteori og refleksionsbegrebet hos Dewey, Dreyfus, Schön, Argyris, Kolb, Jarvis, Mezirow og Brookfield. Afsluttes med diskussion af syntetiseret model for læring på arbejdspladsen.......State of the art inden for forskning om læring på arbejdspladsen samt gennemgang af læringsteori og refleksionsbegrebet hos Dewey, Dreyfus, Schön, Argyris, Kolb, Jarvis, Mezirow og Brookfield. Afsluttes med diskussion af syntetiseret model for læring på arbejdspladsen....

Birth Control Ring

Science.gov (United States)

... Health Food & Fitness Diseases & Conditions Infections Drugs & Alcohol School & Jobs Sports Expert Answers (Q&A) Staying Safe Videos for Educators Search English Español Birth Control Ring KidsHealth / For Teens / Birth Control Ring What's ...

From coffee ring to spherulites ring of poly(ethylene oxide) film from drying droplet

Science.gov (United States)

Hu, Yinchun; Zhang, Xuerong; Qiu, Maibo; Wei, Yan; Zhou, Qiong; Huang, Di

2018-03-01

We discuss how the "spherulites ring" morphology and "coffee ring" profile of PEO film formed by the drying droplet at glass substrate with different heating rate. Upon increasing the heating rate of substrate, it is found that deposited PEO film from drying droplet shows the unusually observed "coffee ring" profile and "spherulites ring" morphology. The main mechanism for this phenomenon is proposed to be an enhanced Marangoni convection which is induced by the increased solute concentration gradient and reduced viscous force above 70 °C. A simple formation mechanism of the unusually observed "coffee ring" profile and "spherulites ring" morphology is proposed. These findings can be exploited to trace the center of Marangoni convection, with potential applications in designing the spherulite patterns of crystalline polymer films in ink-jet printing and self-assembly fields.

Biotransformation of Lactones with Methylcyclohexane Ring and Their Biological Activity

Directory of Open Access Journals (Sweden)

Katarzyna Wińska

2016-12-01

Full Text Available The aim of the study was to obtain biological active compounds during biotransformation. Three bicyclic halolactones with methylcyclohexane ring (2-chloro-4-methyl-9-oxabicyclo-[4.3.0]nonan-8-one, 2-bromo-4-methyl-9-oxabicyclo[4.3.0]nona- -8-one and 2-iodo-4-methyl-9-oxabicyclo[4.3.0]nonan-8-one obtained from the corresponding γ,δ-unsaturated acid were subjected to a screening biotransformation using 22 fungal strains. Two of these strains (Cunninghamella japonica AM472 and Fusarium culmorum AM10 were able to transform halolactones into 2-hydroxy-4-methyl-9-oxabicyclo[4.3.0]nonan-8-one by hydrolytic dehalogenation with good yield. The biotransformation product was structurally different from its synthetically prepared analog. All halolactones and hydroxylactones were tested for their biological activity. The chlorolactone inhibited growth of Staphylococcus aureus (max ΔOD = 0, Escherichia coli (max ΔOD = 0.3 and Candida albicans (max ΔOD = 0 strains. Bromolactone caused inhibition of growth of Staphylococcus aureus (max ΔOD = 0 and Fusarium linii (max ΔOD = 0 strains. Iodolactone limited growth of Staphylococcus aureus (max ΔOD = 0, Escherichia coli (max ΔOD = 0.25, Candida albicans (max ΔOD = 0.45 and Pseudomonas fluorescens (max ΔOD = 0.42 strains. Hydroxylactone caused inhibition of growth of Staphylococcus aureus (max ΔOD = 0.36 and Pseudomonas fluorescens (max ΔOD = 0.39 strains only. The test performed on aphids Myzus persicae (Sulz. showed that chloro- and bromolactone exhibited deterrent activity after 24 h (ID = 0.5 and 0.4, respectively, while hydroxylactone was a weak attractant (ID = −0.3.

Correction of aortic insufficiency with an external adjustable prosthetic aortic ring.

Science.gov (United States)

Gogbashian, Andrew; Ghanta, Ravi K; Umakanthan, Ramanan; Rangaraj, Aravind T; Laurence, Rita G; Fox, John A; Cohn, Lawrence H; Chen, Frederick Y

2007-09-01

Less invasive, valve-sparing options are needed for patients with aortic insufficiency (AI). We sought to evaluate the feasibility of reducing AI with an external adjustable aortic ring in an ovine model. To create AI, five sheep underwent patch plasty enlargement of the aortic annulus and root by placement of a 10 x 15 mm pericardial patch between the right and noncoronary cusps. An adjustable external ring composed of a nylon band was fabricated and placed around the aortic root. Aortic flow, aortic pressure, and left ventricular pressures were measured with the ring loose (off) and tightened (on). Mean regurgitant orifice area decreased by 86%, from 0.07 +/- 0.03 cm2 (ring loose, off) to 0.01 +/- 0.00 cm2 (ring tightened, on) [p < 0.01]. The regurgitant fraction decreased from 18 +/- 4% to 2 +/- 1% [p < 0.01]. The ring did not significantly affect stroke volume and aortic pressure. An ovine model of aortic root dilatation resulting in acute AI has been developed. In this model, application of an external, adjustable constricting aortic ring eliminated AI. An aortic ring may be a useful adjunct in reducing AI secondary to annular dilatation.

Wake patterns behind boulders in the rings of Saturn

International Nuclear Information System (INIS)

Brattli, A.; Havnes, O.; Melandsoe, F.

2002-01-01

The flow of charged dust around an electrically charged boulder moving through an environment thought to be typical of planatery rings is studied. As the boulder moves through the ring dust it will excite a V-shaped Mach cone pattern of a form and complexity which varies significantly with boulder size, relative velocity between the boulder and the dust, and with dust plasma conditions. Parameters relevant to the Saturnian ring system are used to compute examples which demonstrate the change in Mach cone patterns with the relevant parameters. Shortcomings of the model are discussed and ways to improve the calculations of Mach cone patterns are pointed out

Structure and dynamics of ringed galaxies

International Nuclear Information System (INIS)

Buta, R.J.

1984-01-01

In many spiral and SO galaxies, single or multiple ring structures are visible in the disk. These inner rings (r), outer rings (R), and nuclear rings (nr) were investigated by means of morphology, photometry, and spectroscopy in order to provide basic data on a long neglected phenomenon. The metric properties of each ring are investigated and found to correlate with the structure of the parent galaxy. When properly calibrated, inner rings in barred (SB) systems can be used as geometric extragalactic distance indicators to distances in excess of 100 Mpc. Other statistics are presented that confirm previous indications that the rings have preferred shapes, relative sizes, and orientations with respect to bars. A survey is made of the less homogeneous non-barred (SA) ringed systems, and the causes of the inhomogeneity are isolated. It is shown that rings can be identified in multiple-ring SA systems that are exactly analogous to those in barred spirals

Carrier transfer in vertically stacked quantum ring-quantum dot chains

Energy Technology Data Exchange (ETDEWEB)

Mazur, Yu. I., E-mail: ymazur@uark.edu; Dorogan, V. G.; Benamara, M.; Salamo, G. J. [Arkansas Institute for Nanoscale Materials Science and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Lopes-Oliveira, V.; Lopez-Richard, V.; Teodoro, M. D.; Marques, G. E. [Departamento de Fisica, Universidade Federal de São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Souza, L. D. de [Departamento de Fisica, Universidade Federal de São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Arkansas Institute for Nanoscale Materials Science and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Wu, J.; Wang, Z. M. [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China); Tarasov, G. G. [Institute of Semiconductor Physics, National Academy of Sciences, pr. Nauki 45, Kiev 03028 (Ukraine); Marega, E. [Instituto de Fisica de São Carlos, Universidade de São Paulo, 13.566-590 São Carlos, São Paulo (Brazil)

2015-04-21

The interplay between structural properties and charge transfer in self-assembled quantum ring (QR) chains grown by molecular beam epitaxy on top of an InGaAs/GaAs quantum dot (QD) superlattice template is analyzed and characterized. The QDs and QRs are vertically stacked and laterally coupled as well as aligned within each layer due to the strain field distributions that governs the ordering. The strong interdot coupling influences the carrier transfer both along as well as between chains in the ring layer and dot template structures. A qualitative contrast between different dynamic models has been developed. By combining temperature and excitation intensity effects, the tuning of the photoluminescence gain for either the QR or the QD mode is attained. The information obtained here about relaxation parameters, energy scheme, interlayer and interdot coupling resulting in creation of 1D structures is very important for the usage of such specific QR–QD systems for applied purposes such as lasing, detection, and energy-harvesting technology of future solar panels.

The plane strain tests in the PROMETRA program

International Nuclear Information System (INIS)

Cazalis, B.; Desquines, J.; Carassou, S.; Le Jolu, T.; Bernaudat, C.

2016-01-01

A fuel cladding mechanical test, performed under conditions of plane strain deformation in the transverse direction of tube axis, was originally developed at Pennsylvania State University. It was decided to implement this original test within the PROMETRA program using the same experimental procedure and its optimization for a ring mechanical testing on plane strain conditions (PST tests) in hot cells laboratory. This paper presents a detailed description and an interpretation of the Plane Strain Tensile (PST) tests performed in the framework of the PROMETRA program on fresh and irradiated claddings. At first, the context of the PST tests is situated and the specificities of these tests implemented at CEA are justified. Indeed, a significant adjustment of the original experimental procedure is carried out in order to test the irradiated fuel cladding in the best possible conditions. Then, the tests results on fresh Zircaloy-4 and on irradiated Zircaloy-4, M5™ and ZIRLO ® specimens are gathered. The main analyses in support of these tests, such as metallographies, fractographic examinations and finite element simulations are detailed. Finally, a synthesis of the interpretation of the tests is proposed. The PST test seems only representative of plane strain fracture conditions when the test material is very ductile (fresh or high temperature or low hydride material like M5TM). However, it provides a relevant representation of the RIA rupture initiation which is observed in irradiated cladding resulting from hydride rim damage due to the strong irradiation of a fuel rod. - Highlights: • A plane strain mechanical test performed on fuel rod claddings is described. • The tests are performed in the framework of the French PROMETRA program. • Fresh Zircaloy-4 and irradiated Zircaloy-4, M5 and ZIRLO specimens are tested. • The main analyses in support of these tests are detailed. • A synthesis of the interpretation of the PST tests is proposed.

The plane strain tests in the PROMETRA program

Energy Technology Data Exchange (ETDEWEB)

Cazalis, B., E-mail: bernard.cazalis@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire, IRSN/PSN-RES, F-13115 Saint-Paul Lez Durance BP3 (France); Desquines, J. [Institut de Radioprotection et de Sûreté Nucléaire, IRSN/PSN-RES, F-13115 Saint-Paul Lez Durance BP3 (France); Carassou, S.; Le Jolu, T. [Commissariat à l' Energie Atomique, CEA/DEN/DMN, F- 91191 Gif-sur-Yvette (France); Bernaudat, C. [Electricité de France, EDF/SEPTEN, F-69628 Villeurbanne (France)

2016-04-15

A fuel cladding mechanical test, performed under conditions of plane strain deformation in the transverse direction of tube axis, was originally developed at Pennsylvania State University. It was decided to implement this original test within the PROMETRA program using the same experimental procedure and its optimization for a ring mechanical testing on plane strain conditions (PST tests) in hot cells laboratory. This paper presents a detailed description and an interpretation of the Plane Strain Tensile (PST) tests performed in the framework of the PROMETRA program on fresh and irradiated claddings. At first, the context of the PST tests is situated and the specificities of these tests implemented at CEA are justified. Indeed, a significant adjustment of the original experimental procedure is carried out in order to test the irradiated fuel cladding in the best possible conditions. Then, the tests results on fresh Zircaloy-4 and on irradiated Zircaloy-4, M5™ and ZIRLO{sup ®} specimens are gathered. The main analyses in support of these tests, such as metallographies, fractographic examinations and finite element simulations are detailed. Finally, a synthesis of the interpretation of the tests is proposed. The PST test seems only representative of plane strain fracture conditions when the test material is very ductile (fresh or high temperature or low hydride material like M5TM). However, it provides a relevant representation of the RIA rupture initiation which is observed in irradiated cladding resulting from hydride rim damage due to the strong irradiation of a fuel rod. - Highlights: • A plane strain mechanical test performed on fuel rod claddings is described. • The tests are performed in the framework of the French PROMETRA program. • Fresh Zircaloy-4 and irradiated Zircaloy-4, M5 and ZIRLO specimens are tested. • The main analyses in support of these tests are detailed. • A synthesis of the interpretation of the PST tests is proposed.

Multiplicative Structure and Hecke Rings of Generator Matrices for Codes over Quotient Rings of Euclidean Domains

Directory of Open Access Journals (Sweden)

Hajime Matsui

2017-12-01

Full Text Available In this study, we consider codes over Euclidean domains modulo their ideals. In the first half of the study, we deal with arbitrary Euclidean domains. We show that the product of generator matrices of codes over the rings mod a and mod b produces generator matrices of all codes over the ring mod a b , i.e., this correspondence is onto. Moreover, we show that if a and b are coprime, then this correspondence is one-to-one, i.e., there exist unique codes over the rings mod a and mod b that produce any given code over the ring mod a b through the product of their generator matrices. In the second half of the study, we focus on the typical Euclidean domains such as the rational integer ring, one-variable polynomial rings, rings of Gaussian and Eisenstein integers, p-adic integer rings and rings of one-variable formal power series. We define the reduced generator matrices of codes over Euclidean domains modulo their ideals and show their uniqueness. Finally, we apply our theory of reduced generator matrices to the Hecke rings of matrices over these Euclidean domains.

Strain measurements of temperatures up to 3000C in a concrete structure

International Nuclear Information System (INIS)

Schittenhelm, Ch.

1975-10-01

Strain measurements in a concrete structure representing a cylindrical section of a Prestressed Concrete Reactor Vessel with hot liner, were made. In order to interpret these values in terms of strain and stress in a three dimensional structure, the gauge characteristics as well as the material date of the concrete have to be known in great detail. The paper deals with the performance of different gauges embedded in small concrete blocks and others of the same type embedded in the test ring. Temperature resistance, long-time performance, electrical drift and hysteresis of the gauges were investigated. (author)

Binomial Rings: Axiomatisation, Transfer and Classification

OpenAIRE

Xantcha, Qimh Richey

2011-01-01

Hall's binomial rings, rings with binomial coefficients, are given an axiomatisation and proved identical to the numerical rings studied by Ekedahl. The Binomial Transfer Principle is established, enabling combinatorial proofs of algebraical identities. The finitely generated binomial rings are completely classified. An application to modules over binomial rings is given.

AN N-BODY INTEGRATOR FOR GRAVITATING PLANETARY RINGS, AND THE OUTER EDGE OF SATURN'S B RING

International Nuclear Information System (INIS)

Hahn, Joseph M.; Spitale, Joseph N.

2013-01-01

A new symplectic N-body integrator is introduced, one designed to calculate the global 360° evolution of a self-gravitating planetary ring that is in orbit about an oblate planet. This freely available code is called epi i nt, and it is distinct from other such codes in its use of streamlines to calculate the effects of ring self-gravity. The great advantage of this approach is that the perturbing forces arise from smooth wires of ring matter rather than discreet particles, so there is very little gravitational scattering and so only a modest number of particles are needed to simulate, say, the scalloped edge of a resonantly confined ring or the propagation of spiral density waves. The code is applied to the outer edge of Saturn's B ring, and a comparison of Cassini measurements of the ring's forced response to simulations of Mimas's resonant perturbations reveals that the B ring's surface density at its outer edge is σ 0 = 195 ± 60 g cm –2 , which, if the same everywhere across the ring, would mean that the B ring's mass is about 90% of Mimas's mass. Cassini observations show that the B ring-edge has several free normal modes, which are long-lived disturbances of the ring-edge that are not driven by any known satellite resonances. Although the mechanism that excites or sustains these normal modes is unknown, we can plant such a disturbance at a simulated ring's edge and find that these modes persist without any damping for more than ∼10 5 orbits or ∼100 yr despite the simulated ring's viscosity ν s = 100 cm 2 s –1 . These simulations also indicate that impulsive disturbances at a ring can excite long-lived normal modes, which suggests that an impact in the recent past by perhaps a cloud of cometary debris might have excited these disturbances, which are quite common to many of Saturn's sharp-edged rings

Isolation and characterization of atrazine mineralizing Bacillus subtilis strain HB-6.

Directory of Open Access Journals (Sweden)

Jinhua Wang

Full Text Available Atrazine is a widely used herbicide with great environmental concern due to its high potential to contaminate soil and waters. An atrazine-degrading bacterial strain HB-6 was isolated from industrial wastewater and the 16S rRNA gene sequencing identified HB-6 as a Bacillus subtilis. PCR assays indicated that HB-6 contained atrazine-degrading genes trzN, atzB and atzC. The strain HB-6 was capable of utilizing atrazine and cyanuric acid as a sole nitrogen source for growth and even cleaved the s-triazine ring and mineralized atrazine. The strain demonstrated a very high efficiency of atrazine biodegradation with a broad optimum pH and temperature ranges and could be enhanced by cooperating with other bacteria, suggesting its huge potential for remediation of atrazine-contaminated sites. To our knowledge, there are few Bacillus subtilis strains reported that can mineralize atrazine, therefore, the present work might provide some new insights on atrazine remediation.

Galactic rings revisited - I. CVRHS classifications of 3962 ringed galaxies from the Galaxy Zoo 2 Database

Science.gov (United States)

Buta, Ronald J.

2017-11-01

Rings are important and characteristic features of disc-shaped galaxies. This paper is the first in a series that re-visits galactic rings with the goals of further understanding the nature of the features and for examining their role in the secular evolution of galaxy structure. The series begins with a new sample of 3962 galaxies drawn from the Galaxy Zoo 2 citizen science data base, selected because zoo volunteers recognized a ring-shaped pattern in the morphology as seen in Sloan Digital Sky Survey colour images. The galaxies are classified within the framework of the Comprehensive de Vaucouleurs revised Hubble-Sandage system. It is found that zoo volunteers cued on the same kinds of ring-like features that were recognized in the 1995 Catalogue of Southern Ringed Galaxies. This paper presents the full catalogue of morphological classifications, comparisons with other sources of classifications and some histograms designed mainly to highlight the content of the catalogue. The advantages of the sample are its large size and the generally good quality of the images; the main disadvantage is the low physical resolution that limits the detectability of linearly small rings such as nuclear rings. The catalogue includes mainly inner and outer disc rings and lenses. Cataclysmic (`encounter-driven') rings (such as ring and polar ring galaxies) are recognized in less than 1 per cent of the sample.

Internal stress distribution of X-ring using photoelastic experimental hybrid method

Energy Technology Data Exchange (ETDEWEB)

Bernard, Alunda Ouma [Dedan Kimathi University of Technology, Nyeri (Kenya); Hawong, Jai Sug; Lim, Hyun Seok [Yeungnam University, Gyeongsan (Korea, Republic of); Shin, Dong Chul [Koje College, Geoje (Korea, Republic of)

2014-05-15

Sealing elements are essential parts of many machines, and are used to prevent the loss of a fluid or gas. When such fluids are not properly sealed, catastrophic failures may result. Many different types of rings have been developed to suit various industrial needs. Considerable research has been done on the O-ring. We analyze the internal stresses developed in an X-ring under a uniform squeeze rate of 20%, which is suitable for static applications, using a photoelastic experimental hybrid method. The internal pressures applied were 0.98, 1.96, 2.94, 3.92, 4.90, and 5.88 MPa. We show that sealing rings with X geometry have considerably higher internal stresses than O-ring seals. In addition, we demonstrate that after extrusion, for an internal pressure of 5.88 MPa, the two lobes on the upper contact surface merge, thereby increasing the contact length of the upper side significantly. Extrusion in the X-ring occurred when the internal pressure was 4.90 MPa.

Simulated microbe removal around finger rings using different hand sanitation methods.

Science.gov (United States)

Alur, Archana A; Rane, Madhavi J; Scheetz, James P; Lorenz, Douglas J; Gettleman, Lawrence

2009-09-01

It is our opinion that the CDC and the WHO have underestimated cross-contamination under examination gloves in dental clinics while wearing jewelry, such as finger rings. These agencies only "recommend" removing jewelry, and only washing hands for 15 seconds with soap and warm water before donning gloves. This study examined several washing procedures and finger rings using simulated microbes. A gloved rubber hand manikin was made and fitted with a fresh disposable vinyl glove. Four fingers were fitted with rings or no ring, dusted with simulated microbes, and washed with a scrub brush for 5, 15, and 25 seconds under 20 degrees C and 40 degrees C water alone, or with liquid hand soap. Light levels (in lux) of fluorescent powder before and after washing were measured and delta scores calculated for changes in light levels, equivalent to effectiveness of hand washing procedures. A full-factorial, 3-factor analysis of variance (ANOVA) was used to test for differences among levels of the three study factors-time, temperature, and soap use. Tukey's post hoc honestly significant difference (HSD) test was applied to significant factors to examine pair-wise differences between factor levels. It was found that the longer the hands with rings were washed with a scrub brush under flowing water, the more simulated microbes were removed. By 25 seconds, all methods were essentially the same. Simulated microbes were more difficult to remove from the palm compared to the back of the hand. The liquid hand soap used in this study was more effective with warm water than cold. When given a choice of washing with cold water up to 15 seconds, it would be preferable not to use soap to remove simulated microbes. Qualitatively, the outer surface of finger rings were more effectively cleaned than the crevice below the ring, and the ring with a stone setting appeared to accumulate and retain simulated microbes more than other rings. The most effective treatment was washing with warm water

Quantum Fourier Transform Over Galois Rings

OpenAIRE

Zhang, Yong

2009-01-01

Galois rings are regarded as "building blocks" of a finite commutative ring with identity. There have been many papers on classical error correction codes over Galois rings published. As an important warm-up before exploring quantum algorithms and quantum error correction codes over Galois rings, we study the quantum Fourier transform (QFT) over Galois rings and prove it can be efficiently preformed on a quantum computer. The properties of the QFT over Galois rings lead to the quantum algorit...

Novel manifestations of the Aharonov-Bohm effect in quantum rings and Moebius rings

International Nuclear Information System (INIS)

Fomin, Vladimir M.

2013-01-01

- An overview is given on the recent experimental and theoretical advancements in studies of novel manifestations of the Aharonov-Bohm quantum-interference effect for excitons confined to self assembled quantum rings and other semiconductor nanostructures with ring-like states of charge carriers as well as for electrons in Moebius rings at the micro- and nanoscale. The exciton Aharonov-Bohm effect can be effectively controlled by an out-of-plane magnetic field, a vertical electric field, a spin disorder. A 'delocalization-to-localization' transition for the electron ground state occurs in a Moebius ring as it is made more inhomogeneous. (authors)

Ring closure in actin polymers

Energy Technology Data Exchange (ETDEWEB)

Sinha, Supurna, E-mail: supurna@rri.res.in [Raman Research Institute, Bangalore 560080 (India); Chattopadhyay, Sebanti [Doon University, Dehradun 248001 (India)

2017-03-18

We present an analysis for the ring closure probability of semiflexible polymers within the pure bend Worm Like Chain (WLC) model. The ring closure probability predicted from our analysis can be tested against fluorescent actin cyclization experiments. We also discuss the effect of ring closure on bend angle fluctuations in actin polymers. - Highlights: • Ring closure of biopolymers. • Worm like chain model. • Predictions for experiments.

On P-coherent endomorphism rings

Indian Academy of Sciences (India)

A ring is called right -coherent if every principal right ideal is finitely presented. Let M R be a right -module. We study the -coherence of the endomorphism ring of M R . It is shown that is a right -coherent ring if and only if every endomorphism of M R has a pseudokernel in add M R ; S is a left -coherent ring if and ...

Skin patch and vaginal ring versus combined oral contraceptives for contraception.

Science.gov (United States)

Lopez, Laureen M; Grimes, David A; Gallo, Maria F; Stockton, Laurie L; Schulz, Kenneth F

2013-04-30

The delivery of combination contraceptive steroids from a transdermal contraceptive patch or a contraceptive vaginal ring offers potential advantages over the traditional oral route. The transdermal patch and vaginal ring could require a lower dose due to increased bioavailability and improved user compliance. To compare the contraceptive effectiveness, cycle control, compliance (adherence), and safety of the contraceptive patch or the vaginal ring versus combination oral contraceptives (COCs). Through February 2013, we searched MEDLINE, POPLINE, CENTRAL, LILACS, ClinicalTrials.gov, and ICTRP for trials of the contraceptive patch or the vaginal ring. Earlier searches also included EMBASE. For the initial review, we contacted known researchers and manufacturers to identify other trials. We considered randomized controlled trials comparing a transdermal contraceptive patch or a contraceptive vaginal ring with a COC. Data were abstracted by two authors and entered into RevMan. For dichotomous variables, the Peto odds ratio (OR) with 95% confidence intervals (CI) was calculated. For continuous variables, the mean difference was computed. We also assessed the quality of evidence for this review. We found 18 trials that met our inclusion criteria. Of six patch studies, five examined the marketed patch containing norelgestromin plus ethinyl estradiol (EE); one studied a patch in development that contains levonorgestrel (LNG) plus EE. Of 12 vaginal ring trials, 11 examined the same marketing ring containing etonogestrel plus EE; one studied a ring being developed that contains nesterone plus EE.Contraceptive effectiveness was not significantly different for the patch or ring versus the comparison COC. Compliance data were limited. Patch users showed better compliance than COC users in three trials. For the norelgestromin plus EE patch, ORs were 2.05 (95% CI 1.83 to 2.29) and 2.76 (95% CI 2.35 to 3.24). In the levonorgestrel plus EE patch report, patch users were less

Non-Linear Dynamics of Saturn's Rings

Science.gov (United States)

Esposito, L. W.

2016-12-01

Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. Stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, that push the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like `straw' that can explain the halo morphology and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; this requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping explains both small and large particles at resonances. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating it as an asymmetric random walk with reflecting boundaries

Faithfully quadratic rings

CERN Document Server

Dickmann, M

2015-01-01

In this monograph the authors extend the classical algebraic theory of quadratic forms over fields to diagonal quadratic forms with invertible entries over broad classes of commutative, unitary rings where -1 is not a sum of squares and 2 is invertible. They accomplish this by: (1) Extending the classical notion of matrix isometry of forms to a suitable notion of T-isometry, where T is a preorder of the given ring, A, or T = A^2. (2) Introducing in this context three axioms expressing simple properties of (value) representation of elements of the ring by quadratic forms, well-known to hold in

BERKELEY: ALS ring

Energy Technology Data Exchange (ETDEWEB)

Anon.

1993-06-15

Everybody at Lawrence Berkeley Laboratory's Center for Beam Physics is pleased with the rapid progress in commissioning LBL's Advanced Light Source (ALS) electron storage ring, the foundation for this third-generation synchrotron radiation facility. Designed for a maximum current of 400 mA, the ALS storage ring reached 407 mA just 24 days after storing the first beam on 16 March. ALS construction as a US Department of Energy (DOE) national user facility to provide high-brightness vacuum ultra-violet and soft x-ray radiation began in October 1987. One technical requirement marking project completion was to accumulate a 50-mA current in the storage ring. The ALS passed this milestone on 24 March, a week ahead of the official deadline. Once injected, the electron beam decays quasi-exponentially primarily because of interactions with residual gas molecules in the storage-ring vacuum chamber. Eventually, when the pressure in the vacuum chamber with beam decreases toward the expected operating level of 1 nano Torr, it will only be necessary to refill the storage ring at intervals of four to eight hours. At present the vacuum is improving rapidly as surfaces are irradiated (scrubbed) by the synchrotron radiation itself. At 100 mA, beam lifetime was about one hour (9 April)

Compressible Vortex Ring

Science.gov (United States)

Elavarasan, Ramasamy; Arakeri, Jayawant; Krothapalli, Anjaneyulu

1999-11-01

The interaction of a high-speed vortex ring with a shock wave is one of the fundamental issues as it is a source of sound in supersonic jets. The complex flow field induced by the vortex alters the propagation of the shock wave greatly. In order to understand the process, a compressible vortex ring is studied in detail using Particle Image Velocimetry (PIV) and shadowgraphic techniques. The high-speed vortex ring is generated from a shock tube and the shock wave, which precedes the vortex, is reflected back by a plate and made to interact with the vortex. The shadowgraph images indicate that the reflected shock front is influenced by the non-uniform flow induced by the vortex and is decelerated while passing through the vortex. It appears that after the interaction the shock is "split" into two. The PIV measurements provided clear picture about the evolution of the vortex at different time interval. The centerline velocity traces show the maximum velocity to be around 350 m/s. The velocity field, unlike in incompressible rings, contains contributions from both the shock and the vortex ring. The velocity distribution across the vortex core, core diameter and circulation are also calculated from the PIV data.

BERKELEY: ALS ring

International Nuclear Information System (INIS)

Anon.

1993-01-01

Everybody at Lawrence Berkeley Laboratory's Center for Beam Physics is pleased with the rapid progress in commissioning LBL's Advanced Light Source (ALS) electron storage ring, the foundation for this third-generation synchrotron radiation facility. Designed for a maximum current of 400 mA, the ALS storage ring reached 407 mA just 24 days after storing the first beam on 16 March. ALS construction as a US Department of Energy (DOE) national user facility to provide high-brightness vacuum ultra-violet and soft x-ray radiation began in October 1987. One technical requirement marking project completion was to accumulate a 50-mA current in the storage ring. The ALS passed this milestone on 24 March, a week ahead of the official deadline. Once injected, the electron beam decays quasi-exponentially primarily because of interactions with residual gas molecules in the storage-ring vacuum chamber. Eventually, when the pressure in the vacuum chamber with beam decreases toward the expected operating level of 1 nano Torr, it will only be necessary to refill the storage ring at intervals of four to eight hours. At present the vacuum is improving rapidly as surfaces are irradiated (scrubbed) by the synchrotron radiation itself. At 100 mA, beam lifetime was about one hour (9 April)

Accidental ingestion of BiTine ring and a note on inefficient ring separation forceps

Directory of Open Access Journals (Sweden)

Baghele ON

2011-05-01

Full Text Available Om Nemichand Baghele1, Mangala Om Baghele21Department of Periodontology, SMBT Dental College and Hospital, Sangamner, Ahmednagar, Maharashtra, India; 2Private General Dental Practice, Mumbai, IndiaBackground: Accidental ingestion of medium-to-large instruments is relatively uncommon during dental treatment but can be potentially dangerous. A case of BiTine ring ingestion is presented with a note on inefficient ring separation forceps.Case description: A 28-year-old male patient accidentally ingested the BiTine ring (2 cm diameter, 0.5 cm outward projections while it was being applied to a distoproximal cavity in tooth # 19. The ring placement forceps were excessively flexible; bending of the beaks towards the ring combined with a poor no-slippage mechanism led to sudden disengagement of the ring and accelerated movement towards the pharynx. We followed the patient with bulk forming agents and radiographs. Fortunately the ring passed out without any complications.Clinical implications: Checking equipment and methods is as important as taking precautions against any preventable medical emergency. It is the responsibility of the clinician to check, verify and then use any instrument/equipment.Keywords: foreign bodies/radiography, foreign bodies/complications, equipment failure, dental instrument, accidental ingestion

On the Laurent polynomial rings

International Nuclear Information System (INIS)

Stefanescu, D.

1985-02-01

We describe some properties of the Laurent polynomial rings in a finite number of indeterminates over a commutative unitary ring. We study some subrings of the Laurent polynomial rings. We finally obtain two cancellation properties. (author)

Reduction of ring artefacts in high resolution micro-CT reconstructions

International Nuclear Information System (INIS)

Sijbers, Jan; Postnov, Andrei

2004-01-01

High resolution micro-CT images are often corrupted by ring artefacts, prohibiting quantitative analysis and hampering post processing. Removing or at least significantly reducing such artefacts is indispensable. However, since micro-CT systems are pushed to the extremes in the quest for the ultimate spatial resolution, ring artefacts can hardly be avoided. Moreover, as opposed to clinical CT systems, conventional correction schemes such as flat-field correction do not lead to satisfactory results. Therefore, in this note a simple but efficient and fast post processing method is proposed that effectively reduces ring artefacts in reconstructed μ-CT images. (note)

The Hi-Ring DCN Architecture

DEFF Research Database (Denmark)

Galili, Michael; Kamchevska, Valerija; Ding, Yunhong

2016-01-01

We will review recent work on the proposed hierarchical ring-based architecture (HiRing) proposed for data center networks. We will discuss the architecture and initial demonstrations of optical switching performance and time-domain synchronization......We will review recent work on the proposed hierarchical ring-based architecture (HiRing) proposed for data center networks. We will discuss the architecture and initial demonstrations of optical switching performance and time-domain synchronization...

Porcine reproductive and respiratory syndrome virus: Interlaboratory ring trial to evaluate real-time reverse transcription polymerase chain reaction detection methods

DEFF Research Database (Denmark)

Wernike, Kerstin; Bonilauri, Paolo; Dauber, Malte

2012-01-01

To compare the real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) assays used for the diagnosis of Porcine reproductive and respiratory syndrome virus (PRRSV), a Europe-wide interlaboratory ring trial was conducted. A variety of PRRSV strains including North American...... (NA) and European (EU) genotype isolates were analyzed by the participants. Great differences regarding qualitative diagnostics as well as analytical sensitivity were observed between the individual RT-qPCR systems, especially when investigating strains from the EU genotype. None of the assays...

EBT ring physics

International Nuclear Information System (INIS)

Uckan, N.A.

1980-04-01

This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers

Wavelength-selectable and steady single-mode erbium-doped fiber multiple ring laser

Science.gov (United States)

Yeh, Chien-Hung; Yang, Zi-Qing; Huang, Tzu-Jung; Chow, Chi-Wai; Chen, Jing-Heng; Chen, Kun-Huang

2017-11-01

To achieve a stable and selectable C-band erbium-doped fiber (EDF) laser with single-longitudinal-mode output, a multiple ring architecture is proposed and demonstrated experimentally. In this work, we design a passively quadruple-ring structure in the cavity of an EDF laser to produce a Vernier effect with a mode filter for suppressing the multimode spikes significantly. In addition, the output performance and stability of the proposed EDF ring laser are discussed.

Ring cavity surface emitting semiconductor lasers

International Nuclear Information System (INIS)

Mujagic, E.

2010-01-01

�m. Characterizations indicate a high temperature operation of MIR ring-CSELs along with a reduction in threshold current density of MIR devices by 35% as compared to Fabry-Perot devices. The lower operating currents in ring-CSELs became noticeable in continuous wave (CW) operation with a 50K higher maximum temperature than in FP lasers. A two-fold enhancement in radiation efficiency was obtained in MIR and THz ring-CSELs as compared to FP emitters. The DFB grating on top of the resonator gives rise to a single-mode operation of ring-CSELs for all operation currents. Linear wavelength tuning is achieved by fabricating different gratings periods as well as by a variation in temperature. The slope efficiency and the threshold current density does not seem to significantly depend on the grating period, which is attributed to the absence of mirrors. The incorporated circular waveguide geometry along with the surface emitting character gives rise to symmetric and low divergence azimuthally polarized optical beams. The recorded far-fields indicate a ring shaped interference patterns with lobe separations of 1.34 o and 14.14 o for MIR and THz ring-CSELs, respectively. Fabrication of detuned gratings led to a grating period induced as well as to a tunable wavelength induced beam shaping, with beam patterns ranging from spot to wide ring cross sections. (author) [de

Rings Research in the Next Decade

Science.gov (United States)

Burns, J. A.; Tiscareno, M. S.

2009-12-01

The study of planetary ring systems forms a key component of planetary science for several reasons: 1) The evolution and current states of planets and their satellites are affected in many ways by rings, while 2) conversely, properties of planets and moons and other solar system populations are revealed by their effects on rings; 3) highly structured and apparently delicate ring systems may be bellwethers, constraining various theories of the origin and evolution of their entire planetary system; and finally, 4) planetary rings provide an easily observable analogue to other astrophysical disk systems, enabling real “ground truth” results applicable to disks much more remote in space and/or time, including proto-planetary disks, circum-stellar disks, and even galaxies. Significant advances have been made in rings science in the past decade. The highest-priority rings research recommendations of the last Planetary Science Decadal Survey were to operate and extend the Cassini orbiter mission at Saturn; this has been done with tremendous success, accounting for much of the progress made on key science questions, as we will describe. Important progress in understanding the rings of Saturn and other planets has also come from Earth-based observational and theoretical work, again as prioritized by the last Decadal Survey. However, much important work remains to be done. At Saturn, the Cassini Solstice Mission must be brought to a successful completion. Priority should also be placed on sending spacecraft to Neptune and/or Uranus, now unvisited for more than 20 years. At Jupiter and Pluto, opportunities afforded by visiting spacecraft capable of studying rings should be exploited. On Earth, the need for continued research and analysis remains strong, including in-depth analysis of rings data already obtained, numerical and theoretical modeling work, laboratory analysis of materials and processes analogous to those found in the outer solar system, and continued Earth

Strain-induced formation of fourfold symmetric SiGe quantum dot molecules.

Science.gov (United States)

Zinovyev, V A; Dvurechenskii, A V; Kuchinskaya, P A; Armbrister, V A

2013-12-27

The strain field distribution at the surface of a multilayer structure with disklike SiGe nanomounds formed by heteroepitaxy is exploited to arrange the symmetric quantum dot molecules typically consisting of four elongated quantum dots ordered along the [010] and [100] directions. The morphological transition from fourfold quantum dot molecules to continuous fortresslike quantum rings with an increasing amount of deposited Ge is revealed. We examine key mechanisms underlying the formation of lateral quantum dot molecules by using scanning tunneling microscopy and numerical calculations of the strain energy distribution on the top of disklike SiGe nanomounds. Experimental data are well described by a simple thermodynamic model based on the accurate evaluation of the strain dependent part of the surface chemical potential. The spatial arrangement of quantum dots inside molecules is attributed to the effect of elastic property anisotropy.

Token ring technology report

CERN Document Server

2013-01-01

Please note this is a Short Discount publication. This report provides an overview of the IBM Token-Ring technology and products built by IBM and compatible vendors. It consists of two sections: 1. A summary of the design trade-offs for the IBM Token-Ring. 2. A summary of the products of the major token-ring compatible vendors broken down by adapters and components, wiring systems, testing, and new chip technology.

Non-Linear Dynamics of Saturn’s Rings

Science.gov (United States)

Esposito, Larry W.

2015-11-01

Non-linear processes can explain why Saturn’s rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states.Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit.Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like ‘straw’ that can explain the halo structure and spectroscopy: This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn’s rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from results of numerical simulations in the tidal environment surrounding Saturn. Aggregates can explain many dynamic aspects

Nonequilibrium molecular dynamics study of ring polymer melts under shear and elongation flows: A comparison with their linear analogs

Energy Technology Data Exchange (ETDEWEB)

Yoon, Jeongha; Kim, Jinseong; Baig, Chunggi, E-mail: cbaig@unist.ac.kr [Department of Chemical Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of)

2016-07-15

We present detailed results for the structural and rheological properties of unknotted and unconcatenated ring polyethylene (PE) melts under shear and elongation flows via direct atomistic nonequilibrium molecular dynamics simulations. Short (C{sub 78}H{sub 156}) and long (C{sub 400}H{sub 800}) ring PE melts were subjected to planar Couette flow (PCF) and planar elongational flow (PEF) across a wide range of strain rates from linear to highly nonlinear flow regimes. The results are analyzed in detail through a direct comparison with those of the corresponding linear polymers. We found that, in comparison to their linear analogs, ring melts possess rather compact chain structures at or near the equilibrium state and exhibit a considerably lesser degree of structural deformation with respect to the applied flow strength under both PCF and PEF. The large structural resistance of ring polymers against an external flow field is attributed to the intrinsic closed-loop configuration of the ring and the topological constraint of nonconcatenation between ring chains in the melt. As a result, there appears to be a substantial discrepancy between ring and linear systems in terms of their structural and rheological properties such as chain orientation, the distribution of chain dimensions, viscosity, flow birefringence, hydrostatic pressure, the pair correlation function, and potential interaction energies. The findings and conclusions drawn in this work would be a useful guide in future exploration of the characteristic dynamical and relaxation mechanisms of ring polymers in bulk or confined systems under flowing conditions.

Prototype moving-ring reactor

International Nuclear Information System (INIS)

Smith, A.C. Jr.; Ashworth, C.P.; Abreu, K.E.

1982-01-01

We have completed a design of the Prototype Moving-Ring Reactor. The fusion fuel is confined in current-carrying rings of magnetically-field-reversed plasma (Compact Toroids). The plasma rings, formed by a coaxial plasma gun, undergo adiabatic magnetic compression to ignition temperature while they are being injected into the reactor's burner section. The cylindrical burner chamber is divided into three burn stations. Separator coils and a slight axial guide field gradient are used to shuttle the ignited toroids rapidly from one burn station to the next, pausing for 1/3 of the total burn time at each station. D-T- 3 He ice pellets refuel the rings at a rate which maintains constant radiated power

Polycomb Group Proteins RING1A and RING1B Regulate the Vegetative Phase Transition in Arabidopsis

Directory of Open Access Journals (Sweden)

Jian Li

2017-05-01

Full Text Available Polycomb group (PcG protein-mediated gene silencing is a major regulatory mechanism in higher eukaryotes that affects gene expression at the transcriptional level. Here, we report that two conserved homologous PcG proteins, RING1A and RING1B (RING1A/B, are required for global H2A monoubiquitination (H2Aub in Arabidopsis. The mutation of RING1A/B increased the expression of members of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL gene family and caused an early vegetative phase transition. The early vegetative phase transition observed in ring1a ring1b double mutant plants was dependent on an SPL family gene, and the H2Aub status of the chromatin at SPL locus was dependent on RING1A/B. Moreover, mutation in RING1A/B affected the miRNA156a-mediated vegetative phase transition, and RING1A/B and the AGO7-miR390-TAS3 pathway were found to additively regulate this transition in Arabidopsis. Together, our results demonstrate that RING1A/B regulates the vegetative phase transition in Arabidopsis through the repression of SPL family genes.

Researches on the Piston Ring

Science.gov (United States)

Ehihara, Keikiti

1944-01-01

In internal combustion engines, steam engines, air compressors, and so forth, the piston ring plays an important role. Especially, the recent development of Diesel engines which require a high compression pressure for their working, makes, nowadays, the packing action of the piston ring far more important than ever. Though a number of papers have been published in regard to researches on the problem of the piston ring, none has yet dealt with an exact measurement of pressure exerted on the cylinder wall at any given point of the ring. The only paper that can be traced on this subject so far is Mr. Nakagawa's report on the determination of the relative distribution of pressure on the cylinder wall, but the measuring method adopted therein appears to need further consideration. No exact idea has yet been obtained as to how the obturation of gas between the piston and cylinder, the frictional resistance of the piston, and the wear of the cylinder wall are affected by the intensity and the distribution of the radial pressure of the piston ring. Consequently, the author has endeavored, by employing an apparatus of his own invention, to get an exact determination of the pressure distribution of the piston ring. By means of a newly devised ring tester, to which piezoelectricity of quartz was applied, the distribution of the radial pressure of many sample rings on the market was accurately determined. Since many famous piston rings show very irregular pressure distribution, the author investigated and achieved a manufacturing process of the piston ring which will exert uniform pressure on the cylinder wall. Temperature effects on the configuration and on the mean spring power have also been studied. Further, the tests were performed to ascertain how the gas tightness of the piston ring may be affected by the number or spring power. The researches as to the frictional resistance between the piston ring and the cylinder wall were carried out, too. The procedure of study, and

Generation of stable mixed-compact-toroid rings by inducing plasma currents in strong E rings

International Nuclear Information System (INIS)

Jayakumar, R.; Taggart, D.P.; Parker, M.R.; Fleischmann, H.H.

1989-01-01

In the RECE-Christa device, hybrid-type compact toroid rings are generated by inducing large toroidal plasma currents I rho in strong electron rings using a thin induction coil positioned along the ring axis. Starting from field-reversal values δ ο = 50 - 120 percent of the original pure fast-electron ring, the induced plasma current I rho raises δ to a maximum value of up to 240 percent with I rho contributing more than 50 percent of the total ring current. Quite interestingly, the generated hybrid compact toroid configurations appear gross-stable during the full I rho pulse length (half-amplitude width about 100 μs)

Optical Properties of a Quantum Dot-Ring System Grown Using Droplet Epitaxy.

Science.gov (United States)

Linares-García, Gabriel; Meza-Montes, Lilia; Stinaff, Eric; Alsolamy, S M; Ware, M E; Mazur, Y I; Wang, Z M; Lee, Jihoon; Salamo, G J

2016-12-01

Electronic and optical properties of InAs/GaAs nanostructures grown by the droplet epitaxy method are studied. Carrier states were determined by k · p theory including effects of strain and In gradient concentration for a model geometry. Wavefunctions are highly localized in the dots. Coulomb and exchange interactions are studied and we found the system is in the strong confinement regime. Microphotoluminescence spectra and lifetimes were calculated and compared with measurements performed on a set of quantum rings in a single sample. Some features of spectra are in good agreement.

Magnetization of two coupled rings

International Nuclear Information System (INIS)

Avishai, Y; Luck, J M

2009-01-01

We investigate the persistent currents and magnetization of a mesoscopic system consisting of two clean metallic rings sharing a single contact point in a magnetic field. Many novel features with respect to the single-ring geometry are underlined, including the explicit dependence of wavefunctions on the Aharonov-Bohm fluxes, the complex pattern of two-fold and three-fold degeneracies, the key role of length and flux commensurability, and in the case of commensurate ring lengths the occurrence of idle levels which do not carry any current. Spin-orbit interactions, induced by the electric fields of charged wires threading the rings, give rise to a peculiar version of the Aharonov-Casher effect where, unlike for a single ring, spin is not conserved. Remarkably enough, this can only be realized when the Aharonov-Bohm fluxes in both rings are neither integer nor half-integer multiples of the flux quantum

Regulation of hydantoin-hydrolyzing enzyme expression in Agrobacterium tumefaciens strain RU-AE01.

Science.gov (United States)

Jiwaji, Meesbah; Dorrington, Rosemary Ann

2009-10-01

Optically pure D-: amino acids, like D-: hydroxyphenylglycine, are used in the semi-synthetic production of pharmaceuticals. They are synthesized industrially via the biocatalytic hydrolysis of p-hydroxyphenylhydantoin using enzymes derived from Agrobacterium tumefaciens strains. The reaction proceeds via a three-step pathway: (a) the ring-opening cleavage of the hydantoin ring by a D-: hydantoinase (encoded by hyuH), (b) conversion of the resultant D-: N-carbamylamino acid to the corresponding amino acid by a D-: N-carbamoylase (encoded by hyuC), and (c) chemical or enzymatic racemization of the un-reacted hydantoin substrate. While the structure and biochemical properties of these enzymes are well understood, little is known about their origin, their function, and their regulation in the native host. We investigated the mechanisms involved in the regulation of expression of the hydantoinase and N-carbamoylase enzyme activity in A. tumefaciens strain RU-AE01. We present evidence for a complex regulatory network that responds to the growth status of the cells, the presence of inducer, and nitrogen catabolite repression. Deletion analysis and site-directed mutagenesis were used to identify regulatory elements involved in transcriptional regulation of hyuH and hyuC expression. Finally, a comparison between the hyu gene clusters in several Agrobacterium strains provides insight into the function of D-: selective hydantoin-hydrolyzing enzyme systems in Agrobacterium species.

Radioactive gold ring dermatitis

International Nuclear Information System (INIS)

Miller, R.A.; Aldrich, J.E.

1990-01-01

A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy

Analytical model for double split ring resonators with arbitrary ring width

DEFF Research Database (Denmark)

Zhurbenko, Vitaliy; Jensen, Thomas; Krozer, Viktor

2008-01-01

For the first time, the analytical model for a double split ring resonator with unequal width rings is developed. The proposed models for the resonators with equal and unequal widths are based on an impedance matrix representation and provide the prediction of performance in a wide frequency range...

Pure subrings of the rings Zχ

International Nuclear Information System (INIS)

Tsarev, Andrei V

2009-01-01

Pure subrings of finite rank in the Z-adic completion of the ring of integers and in its homomorphic images are considered. Certain properties of these rings are studied (existence of an identity element, decomposability into a direct sum of essentially indecomposable ideals, condition for embeddability into a csp-ring, etc.). Additive groups of these rings and conditions under which these rings are subrings of algebraic number fields are described. Bibliography: 12 titles.

Theory of electron energy spectrum and Aharonov-Bohm effect in self-assembled Inx Ga1-x As quantum rings in GaAs

NARCIS (Netherlands)

Fomin, V.M.; Gladilin, V.N.; Klimin, S.N.; Devreese, J.T.; Kleemans, N.A.J.M.; Koenraad, P.M.

2007-01-01

We analyze theoretically the electron energy spectrum and the magnetization of an electron in a strained Inx Ga1-x As GaAs self-assembled quantum ring (SAQR) with realistic parameters, determined from the cross-sectional scanning-tunneling microscopy characterization of that nanostructure. The SAQRs

Prevalent hallucinations during medical internships: phantom vibration and ringing syndromes.

Directory of Open Access Journals (Sweden)

Yu-Hsuan Lin

Full Text Available BACKGROUND: Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. METHODS: A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying symptoms of anxiety and depression were evaluated with the Beck Anxiety and Depression Inventories before the internship began, and again at the third, sixth, and twelfth internship months, and two weeks after the internship ended. RESULTS: The baseline prevalence of phantom vibration was 78.1%, which increased to 95.9% and 93.2% in the third and sixth internship months. The prevalence returned to 80.8% at the twelfth month and decreased to 50.0% 2 weeks after the internship ended. The baseline prevalence of phantom ringing was 27.4%, which increased to 84.9%, 87.7%, and 86.3% in the third, sixth, and twelfth internship months, respectively. This returned to 54.2% two weeks after the internship ended. The anxiety and depression scores also increased during the internship, and returned to baseline two weeks after the internship. There was no significant correlation between phantom vibration/ringing and symptoms of anxiety or depression. The incidence of both phantom vibration and ringing syndromes significantly increased during the internship, and subsequent recovery. CONCLUSION: This study suggests that phantom vibration and ringing might be entities that are independent of anxiety or depression during evaluation of stress-associated experiences during medical internships.

Ring accelerators

International Nuclear Information System (INIS)

Gisler, G.; Faehl, R.

1983-01-01

We present two-dimensional simulations in (r-z) and r-theta) cylinderical geometries of imploding-liner-driven accelerators of rings of charged particles. We address issues of azimuthal and longitudinal stability of the rings. We discuss self-trapping designs in which beam injection and extraction is aided by means of external cusp fields. Our simulations are done with the 2-1/2-D particle-in-cell plasma simulation code CLINER, which combines collisionless, electromagnetic PIC capabilities with a quasi-MHD finite element package

Manipulation of vortex rings for flow control

International Nuclear Information System (INIS)

Toyoda, Kuniaki; Hiramoto, Riho

2009-01-01

This paper reviews the dynamics of vortex rings and the control of flow by the manipulation of vortex rings. Vortex rings play key roles in many flows; hence, the understanding of the dynamics of vortex rings is crucial for scientists and engineers dealing with flow phenomena. We describe the structures and motions of vortex rings in circular and noncircular jets, which are typical examples of flows evolving into vortex rings. For circular jets the mechanism of evolving, merging and breakdown of vortex rings is described, and for noncircular jets the dynamics of three-dimensional deformation and interaction of noncircular vortex rings under the effect of self- and mutual induction is discussed. The application of vortex-ring manipulation to the control of various flows is reviewed with successful examples, based on the relationship between the vortex ring dynamics and the flow properties. (invited paper)

GRAVITATIONAL ACCRETION OF PARTICLES ONTO MOONLETS EMBEDDED IN SATURN's RINGS

International Nuclear Information System (INIS)

Yasui, Yuki; Ohtsuki, Keiji; Daisaka, Hiroshi

2014-01-01

Using a local N-body simulation, we examine gravitational accretion of ring particles onto moonlet cores in Saturn's rings. We find that gravitational accretion of particles onto moonlet cores is unlikely to occur in the C ring and probably difficult in the inner B ring as well provided that the cores are rigid water ice. Dependence of particle accretion on ring thickness changes when the radial distance from the planet and/or the density of particles is varied: the former determines the size of the core's Hill radius relative to its physical size, while the latter changes the effect of self-gravity of accreted particles. We find that particle accretion onto high-latitude regions of the core surface can occur even if the rings' vertical thickness is much smaller than the core radius, although redistribution of particles onto the high-latitude regions would not be perfectly efficient in outer regions of the rings such as the outer A ring, where the size of the core's Hill sphere in the vertical direction is significantly larger than the core's physical radius. Our results suggest that large boulders recently inferred from observations of transparent holes in the C ring are not formed locally by gravitational accretion, while propeller moonlets in the A ring would be gravitational aggregates formed by particle accretion onto dense cores. Our results also imply that the main bodies of small satellites near the outer edge of Saturn's rings may have been formed in rather thin rings

GRAVITATIONAL ACCRETION OF PARTICLES ONTO MOONLETS EMBEDDED IN SATURN's RINGS

Energy Technology Data Exchange (ETDEWEB)

Yasui, Yuki; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Daisaka, Hiroshi, E-mail: y.yasui@whale.kobe-u.ac.jp, E-mail: ohtsuki@tiger.kobe-u.ac.jp [Graduate School of Commerce and Management, Hitotsubashi University, Tokyo 186-8601 (Japan)

2014-12-20

Using a local N-body simulation, we examine gravitational accretion of ring particles onto moonlet cores in Saturn's rings. We find that gravitational accretion of particles onto moonlet cores is unlikely to occur in the C ring and probably difficult in the inner B ring as well provided that the cores are rigid water ice. Dependence of particle accretion on ring thickness changes when the radial distance from the planet and/or the density of particles is varied: the former determines the size of the core's Hill radius relative to its physical size, while the latter changes the effect of self-gravity of accreted particles. We find that particle accretion onto high-latitude regions of the core surface can occur even if the rings' vertical thickness is much smaller than the core radius, although redistribution of particles onto the high-latitude regions would not be perfectly efficient in outer regions of the rings such as the outer A ring, where the size of the core's Hill sphere in the vertical direction is significantly larger than the core's physical radius. Our results suggest that large boulders recently inferred from observations of transparent holes in the C ring are not formed locally by gravitational accretion, while propeller moonlets in the A ring would be gravitational aggregates formed by particle accretion onto dense cores. Our results also imply that the main bodies of small satellites near the outer edge of Saturn's rings may have been formed in rather thin rings.

The Rings of Saturn

Science.gov (United States)

Cuzzi, J. N.; Filacchione, G.; Marouf, E. A.

2018-03-01

One could become an expert on Saturn's iconic rings pretty easily in the early 1970s, as very little was known about them beyond the distinction between the A, B, and C rings, and the Cassini Division or "gap" between rings A and B (Alexander, 1962; Bobrov, 1970). Water ice was discovered spectroscopically on the ring particle surfaces, and radar and microwave emission observations proved that the particles must be centimeters to meters in size, consisting primarily, not just superficially, of water ice (Pollack, 1975). While a 2:1 orbital resonance with Mimas had long been suspected of having something to do with the Cassini Division, computers of the time were unable to model the subtle dynamical effects that we now know to dominate ring structure. This innocent state of affairs was exploded by the Voyager 1 and 2 encounters in 1980 and 1981. Spectacular images revealed filigree structure and odd regional color variations, and exquisitely detailed radial profiles of fluctuating particle abundance were obtained from the first stellar and radio occultations, having resolution almost at the scale of single particles. Voyager-era understanding was reviewed by Cuzzi et al. (1984) and Esposito et al. (1984). While the Voyager data kept ring scientists busy for decades, planning which led to the monumentally successful NASA-ESA-ASI Cassini mission, which arrived in 2004, had been under way even before Voyager got to Saturn. A review of pre-Cassini knowledge of Saturn's Rings can be found in Orton et al. (2009). This chapter will build on recent topical and process-specific reviews that treat the gamut of ring phenomena and its underlying physics in considerable detail (Colwell et al., 2009; Cuzzi et al., 2009; Horányi et al., 2009; Schmidt et al., 2009; Esposito, 2010; Tiscareno, 2013b; Esposito, 2014). We will follow and extend the general organization of Cuzzi et al. (2010), the most recent general discussion of Saturn's rings. For brevity and the benefit of the

Synthesis of a natural product-inspired eight-membered ring lactam library via ring-closing metathesis.

Science.gov (United States)

Brown, Neil; Xie, Baohan; Markina, Nataliya; Vandervelde, David; Perchellet, Jean-Pierre H; Perchellet, Elisabeth M; Crow, Kyle R; Buszek, Keith R

2008-09-01

We have prepared a novel speculative eight-membered lactam demonstration library based on the skeletal structure of the potent antitumor marine natural product octalactin A. The basic scaffold was readily constructed in a convergent fashion via ring-closing metathesis chemistry from the corresponding diene amides. A cursory examination of the biological properties of the library validates the relevance and significance of these structures.

Examination techniques for non-magnetic rings

International Nuclear Information System (INIS)

Metala, M.J.; Kilpatrick, N.L.; Frank, W.W.

1990-01-01

Until the introduction of 18Mn18Cr rings a few years ago, most non-magnetic steel rings for generator rotors were made from 18Mn5Cr alloy steel, which is highly susceptible to stress corrosion cracking in the presence of water. This, the latest in a series of papers on the subject of non-magnetic rings by the authors' company, provides a discussion of nondestructive examination of 18Mn5Cr rings for stress corrosion distress. With rings on the rotor, fluorescent penetrant, ultrasonic and special visual techniques are applied. With rings off the rotor, the fluorescent penetrant technique is used, with and without stress enhancement

An autonomous strain-based Structural Monitoring Framework for Life-Cycle Analysis of a Novel Structure

Directory of Open Access Journals (Sweden)

Yunus Emre Harmanci

2016-07-01

Full Text Available In recent years, developed societies have largely adopted smart systems operating on the basis of information extracted from data. For infrastructure systems as well, Structural Health Monitoring (SHM has long advocated a data-driven scheme for facilitating the operation and maintenance of infrastructure. In materializing such a goal, this paper demonstrates the procedures and outcomes of a SHM framework employed on an unconventional structure, namely the recently built Kaeng Krachan Elephant Shelter at the Zurich Zoo, relying on a deployed set of Fiber Bragg Grating (FBG strain sensors. The structure comprises an 80 meter span free-form timber-composite cupola, carried by a post-tensioned reinforced concrete (RC ring. FBG strain sensors are embedded into the ring in close vicinity to critical regions, selected in collaboration with the design engineers. The continuously acquired strain data is then exploited for extraction of performance indicators, relying on implementation of output-only identification methodologies. To this end, a non-parametric and a parametric output-only method, namely a Principal Component Analysis (PCA scheme versus a Vector AutoRegressive (VAR model, are employed and compared. Pre-conditioning of the predictive model is performed on the healthy, or undamaged, state of the structure, and the misfit between model predictions and subsequent measurements is exploited as a damage precursor. The VAR scheme proves in this case a more robust representation of the measured strains, when compared against PCA, as a result of its inherent feature of memory.

Size and strain tunable band alignment of black-blue phosphorene lateral heterostructures.

Science.gov (United States)

Li, Yan; Ma, Fei

2017-05-17

Single-element lateral heterostructures composed of black and blue phosphorene are not only free from lattice mismatch but also exhibit rich physical properties related to the seamlessly stitched interfaces, providing the building blocks for designing atomically thin devices. Using first-principles calculations, we investigate the influence of interface structure, size effect and strain engineering on the electronic structure, effective masses and band alignment of black-blue phosphorene lateral heterostructures. The lateral heterostructure with an octatomic-ring interface presents a strong metallic feature due to the interface states, while a metal-semiconductor transition takes place in the system with a hexatomic-ring interface upon hydrogen passivation. Following a reciprocal scaling law, the band gap is tuned in a wide energy range by synchronously increasing the widths of black and blue phosphorene or by only widening that of black phosphorene. Moreover, type-II band alignment is observed in the width ranges of 2.0-3.1 nm and 3.7-4.2 nm, out of which it is type-I. However, the band gap and effective masses show small changes if only the width of blue phosphorene is altered. When the lateral heterostructure is tensile loaded, the effective mass ratio of hole to electron is enlarged by an order of magnitude at a strain of 4% along the zigzag direction. Meanwhile, the band alignment undergoes a crossover from type-I to type-II at a strain of 2%, facilitating efficient electron-hole separation for light detection and harvesting.

Ionization cooling ring for muons

Directory of Open Access Journals (Sweden)

R. Palmer

2005-06-01

Full Text Available Practical ionization cooling rings could lead to lower cost or improved performance in neutrino factory or muon collider designs. The ring modeled here uses realistic three-dimensional fields. The performance of the ring compares favorably with the linear cooling channel used in the second U.S. Neutrino Factory Study. The normalized 6D emittance of an ideal ring is decreased by a factor of approximately 240, compared with a factor of only 15 for the linear channel. We also examine such real-world effects as windows on the absorbers and rf cavities and leaving empty lattice cells for injection and extraction. For realistic conditions the ring decreases the normalized 6D emittance by a factor of 49.

An engineered Lactococcus lactis strain exerts significant immune responses through efficient expression and delivery of Helicobacter pylori Lpp20 antigen.

Science.gov (United States)

Zhang, Rongguang; Peng, Xiaoyan; Duan, Guangcai; Shi, Qingfeng; Chen, Shuaiyin; Wang, Chen; Fan, Qingtang; Xi, Yuanlin

2016-12-01

To produce and deliver Helicobacter pylori lipoprotein Lpp20 via using Lactococcus lactis with aim of developing an efficient way to use this protective antigen in vaccine formulation. An engineered L. lactis strain carrying the lpp20 gene from H. pylori was constructed. The inducible expression of Lpp20 in L. lactis was detected as a 20 kDa intracellular protein by SDS-PAGE. Lpp20 constituted 10 % of the L. lactis cellular proteins. The expression product was highly immunoreactive, as demonstrated by western blot assays using mouse anti-H. pylori sera. Animal experimentation showed that oral vaccination with the engineered strain excited significantly elevated levels of serum Lpp20-specific IgG antibodies in BALB/c mice (P lactis, demonstrating an efficient utilization mode of Lpp20 in anti-H. pylori vaccination.

Storm-time ring current: model-dependent results

Directory of Open Access Journals (Sweden)

N. Yu. Ganushkina

2012-01-01

Full Text Available The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT on 6–7 November 1997 and one intense (SymH minimum of −230 nT on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM, in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.

Self-gravitation in Saturn's rings

International Nuclear Information System (INIS)

Salo, H.; Lukkari, J.

1982-01-01

In a ring-shaped collisional system self-gravitation reduces the equilibrium values of the geometric and optical thickness. In Saturn's rings both effects are appreciable. The previously found discrepancy between the calculated profile and the observed profile of the rings is chiefly caused by the omission of self-gravitation. (Auth.)

Ab Initio Calculations of 31P NMR Chemical Shielding Anisotropy Tensors in Phosphates: Variations Due to Ring Formation

Directory of Open Access Journals (Sweden)

Todd M. Alam

2002-08-01

Full Text Available Abstract: Ring formation in phosphate systems is expected to influence both the magnitude and orientation of the phosphorus (31P nuclear magnetic resonance (NMR chemical shielding anisotropy (CSA tensor. Ab initio calculations of the 31P CSA tensor in both cyclic and acyclic phosphate clusters were performed as a function of the number of phosphate tetrahedral in the system. The calculation of the 31P CSA tensors employed the GAUSSIAN 98 implementation of the gauge-including atomic orbital (GIAO method at the Hartree-Fock (HF level. It is shown that both the 31P CSA tensor anisotropy, and the isotropic chemical shielding can be used for the identification of cyclic phosphates. The differences between the 31P CSA tensor in acyclic and cyclic phosphate systems become less pronounced with increasing number of phosphate groups within the ring. The orientation of the principal components for the 31P CSA tensor shows some variation due to cyclization, most notably with the smaller, highly strained ring systems.

Lactic Acid Yield Using Different Bacterial Strains, Its Purification, and Polymerization through Ring-Opening Reactions

Directory of Open Access Journals (Sweden)

F. G. Orozco

2014-01-01

Full Text Available Laboratory-scale anaerobic fermentation was performed to obtain lactic acid from lactose, using five lactic acid bacteria: Lactococcus lactis, Lactobacillus bulgaricus, L. delbrueckii, L. plantarum, and L. delbrueckii lactis. A yield of 0.99 g lactic acid/g lactose was obtained with L. delbrueckii, from which a final concentration of 80.95 g/L aqueous solution was obtained through microfiltration, nanofiltration, and inverse osmosis membranes. The lactic acid was polymerized by means of ring-opening reactions (ROP to obtain poly-DL-lactic acid (PDLLA, with a viscosity average molecular weight (Mv of 19,264 g/mol.

Split ring containment attachment device

International Nuclear Information System (INIS)

Sammel, A.G.

1996-01-01

A containment attachment device is described for operatively connecting a glovebag to plastic sheeting covering hazardous material. The device includes an inner split ring member connected on one end to a middle ring member wherein the free end of the split ring member is inserted through a slit in the plastic sheeting to captively engage a generally circular portion of the plastic sheeting. A collar potion having an outer ring portion is provided with fastening means for securing the device together wherein the glovebag is operatively connected to the collar portion. 5 figs

An N-body Integrator for Planetary Rings

Science.gov (United States)

Hahn, Joseph M.

2011-04-01

A planetary ring that is disturbed by a satellite's resonant perturbation can respond in an organized way. When the resonance lies in the ring's interior, the ring responds via an m-armed spiral wave, while a ring whose edge is confined by the resonance exhibits an m-lobed scalloping along the ring-edge. The amplitude of these disturbances are sensitive to ring surface density and viscosity, so modelling these phenomena can provide estimates of the ring's properties. However a brute force attempt to simulate a ring's full azimuthal extent with an N-body code will likely fail because of the large number of particles needed to resolve the ring's behavior. Another impediment is the gravitational stirring that occurs among the simulated particles, which can wash out the ring's organized response. However it is possible to adapt an N-body integrator so that it can simulate a ring's collective response to resonant perturbations. The code developed here uses a few thousand massless particles to trace streamlines within the ring. Particles are close in a radial sense to these streamlines, which allows streamlines to be treated as straight wires of constant linear density. Consequently, gravity due to these streamline is a simple function of the particle's radial distance to all streamlines. And because particles are responding to smooth gravitating streamlines, rather than discrete particles, this method eliminates the stirring that ordinarily occurs in brute force N-body calculations. Note also that ring surface density is now a simple function of streamline separations, so effects due to ring pressure and viscosity are easily accounted for, too. A poster will describe this N-body method in greater detail. Simulations of spiral density waves and scalloped ring-edges are executed in typically ten minutes on a desktop PC, and results for Saturn's A and B rings will be presented at conference time.

Minimal Gromov-Witten rings

International Nuclear Information System (INIS)

Przyjalkowski, V V

2008-01-01

We construct an abstract theory of Gromov-Witten invariants of genus 0 for quantum minimal Fano varieties (a minimal class of varieties which is natural from the quantum cohomological viewpoint). Namely, we consider the minimal Gromov-Witten ring: a commutative algebra whose generators and relations are of the form used in the Gromov-Witten theory of Fano varieties (of unspecified dimension). The Gromov-Witten theory of any quantum minimal variety is a homomorphism from this ring to C. We prove an abstract reconstruction theorem which says that this ring is isomorphic to the free commutative ring generated by 'prime two-pointed invariants'. We also find solutions of the differential equation of type DN for a Fano variety of dimension N in terms of the generating series of one-pointed Gromov-Witten invariants

Stability of Moonlets Embedded in Rings

Science.gov (United States)

Lewis, Mark C.; Burdon, C.

2011-04-01

Previous work on moonlets assumed that they were just a single indestructible spherical particle and focused primarily on the effects such a body would have on the surrounding ring material (Lewis and Stewart 2009, Icarus 199:387-412; Sremcevic et al. 2007, Nature 449:1019-1021). Both observations and numerical simulations of Saturn's small inner moons show them as very low density rubble piles (Porco et al. 2007, Science 318:1602). Unlike the small moons, moonlets embedded in the ring material will experience regular collisions with self gravity wakes tens of meters across. Even with a single spherical core, these collisions can lead to the shedding of significant amounts of accreted material. We describe numerical simulations in which we explore the parameters required for stability of moonlets embedded in the ring material. Because of their location well inside the Roche limit, these bodies require either higher densities or some internal strength in order to stay together. We explore how much strength is required for these moonlets to be stable against the regular impacts they sustain in that environment. This work was funded by NSF AAG award number 0907972.

Two superconducting storage rings: ISABELLE

International Nuclear Information System (INIS)

Sanford, J.R.

1978-01-01

The general features of the design and the status of the ISABELLE storage ring project at the present time are reported. It brings up to date the results reported at the National Particle Accelerator Conference in March 1977. The most significant change since that time has been an upgrading of the energy of the overall facility, and acceptance of the project by the Department of Energy

Electro-optical hybrid slip ring

Science.gov (United States)

Hong, En

2005-11-01

The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility

Double acting stirling engine piston ring

Science.gov (United States)

Howarth, Roy B.

1986-01-01

A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

Factors affecting finite strain estimation in low-grade, low-strain clastic rocks

Science.gov (United States)

Pastor-Galán, Daniel; Gutiérrez-Alonso, Gabriel; Meere, Patrick A.; Mulchrone, Kieran F.

2009-12-01

The computer strain analysis methods SAPE, MRL and DTNNM have permitted the characterization of finite strain in two different regions with contrasting geodynamic scenarios; (1) the Talas Ala Tau (Tien Shan, Kyrgyzs Republic) and (2) the Somiedo Nappe and Narcea Antiform (Cantabrian to West Asturian-Leonese Zone boundary, Variscan Belt, NW of Iberia). The performed analyses have revealed low-strain values and the regional strain trend in both studied areas. This study also investigates the relationship between lithology (grain size and percentage of matrix) and strain estimates the two methodologies used. The results show that these methods are comparable and the absence of significant finite strain lithological control in rocks deformed under low metamorphic and low-strain conditions.

Fusion Rings for Quantum Groups

DEFF Research Database (Denmark)

Andersen, Henning Haahr; Stroppel, Catharina

2012-01-01

We study the fusion rings of tilting modules for a quantum group at a root of unity modulo the tensor ideal of negligible tilting modules. We identify them in type A with the combinatorial rings from [12] and give a similar description of the sp2n-fusion ring in terms of noncommutative symmetric...

Topological rings

CERN Document Server

Warner, S

1993-01-01

This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

Energy spectra of quantum rings.

Science.gov (United States)

Fuhrer, A; Lüscher, S; Ihn, T; Heinzel, T; Ensslin, K; Wegscheider, W; Bichler, M

2001-10-25

Quantum mechanical experiments in ring geometries have long fascinated physicists. Open rings connected to leads, for example, allow the observation of the Aharonov-Bohm effect, one of the best examples of quantum mechanical phase coherence. The phase coherence of electrons travelling through a quantum dot embedded in one arm of an open ring has also been demonstrated. The energy spectra of closed rings have only recently been studied by optical spectroscopy. The prediction that they allow persistent current has been explored in various experiments. Here we report magnetotransport experiments on closed rings in the Coulomb blockade regime. Our experiments show that a microscopic understanding of energy levels, so far limited to few-electron quantum dots, can be extended to a many-electron system. A semiclassical interpretation of our results indicates that electron motion in the rings is governed by regular rather than chaotic motion, an unexplored regime in many-electron quantum dots. This opens a way to experiments where even more complex structures can be investigated at a quantum mechanical level.

Forandringslæring med autismediagnoser?

DEFF Research Database (Denmark)

Gustafson, Kari Ingrid; Mørck, Line Lerche

2013-01-01

Artiklen drøfter en række aktuelle spørgsmål omkring læring hos børn og unge med autisme-spektrum-forstyrrelses diagnoser. Der introduceres til en social praksisteoretisk forståelse af forandringslæring, der diskuterer forandring ikke kun i relation til en persons identitet, men også aktuelle og...... potentielle forandringer, når det gælder overskridelse af binær logik i autisme versus normalitet, samt i relation til at overskride individualiserede og dualistiske problem-forståelser af fejl og mangler ved det autistiske barn. Det illustreres, hvordan disse former for dualistisk tænkning er forankret i et...... Rasmus’ ændringer i læring, selvforståelse og tilhørsforhold perspektiveres med andre ASF-diagnostiseredes læring udforsket bl.a. gennem gruppeinterviews i regi af Asperger-foreningen. Artiklen byder således på et alternativ i form af at forstå forandringslæring som overskridende læring, med langt større...

The Lord of Rings - the mysterious case of the stolen rings: a critical analysis

Science.gov (United States)

Sandrelli, S.

The Lord of Rings - the mysterious case of the stolen rings: a critical analysis S. Sandrelli INAF - Osservatorio Astronomico di Brera, Milano, Italy (stefano.sandrelli@brera.inaf.it / Fax: 02 72001600 / Phone: +39 02 72320337) "The Lord of Rings - the mysterious case of the stolen rings" is a live astronomical role-playing game for kids aged 10 -13. Its goal is to introduce them to some of the main topics of the Solar System: a) the role of gravity; b) the distribution of mass & light; c) the effects of rotation; d) the distribution of water. The game was held both at the Perugia (2004) and the Genova Science Festival (2005), obtaining great success. Teams of about 6-8 members are introduced to Mr Schioppanelli, the astro-detective of the town (the name is a pun: it reminds Schiaparelli, the famous italian astronomer, and it is a slang expression meaning "ring-breaker"). Mr Schioppanelli has his office in an "gastronomical astronomical observatory", known as The Red Giant Pizzeria. Schioppanelli informs the kids that a mysterious Centaur succeded in stealing the rings of Saturn. The partecipants are appointed astro-detectives in-charge and asked to find the rings by browsing around the Solar System, which is scaled so as to fit the town historical centre or a pedestrian area, going from the Sun to Saturn or beyond, depending on the actual area at disposal. Great care must be taken allowing children playing only in a car-free area of the town. At the right scaled distances, the partecipants meet characters playing as the various planets. The kids can talk to them after solving a riddle, obtaining useful informations. A special characters play as a comet, timely going in and out of the inner solar system. The teams can also talk to some shepherd-moons of the rings. They easily discover that the rings were totally destroyed by the Centaur: a real disaster! They are also suggested to gather the necessary ingredients (gravity, light, rotation, inclination, dust and

Optical control of spin-dependent thermal transport in a quantum ring

Science.gov (United States)

Abdullah, Nzar Rauf

2018-05-01

We report on calculation of spin-dependent thermal transport through a quantum ring with the Rashba spin-orbit interaction. The quantum ring is connected to two electron reservoirs with different temperatures. Tuning the Rashba coupling constant, degenerate energy states are formed leading to a suppression of the heat and thermoelectric currents. In addition, the quantum ring is coupled to a photon cavity with a single photon mode and linearly polarized photon field. In a resonance regime, when the photon energy is approximately equal to the energy spacing between two lowest degenerate states of the ring, the polarized photon field can significantly control the heat and thermoelectric currents in the system. The roles of the number of photon initially in the cavity, and electron-photon coupling strength on spin-dependent heat and thermoelectric currents are presented.

Vortex rings in classical and quantum systems

International Nuclear Information System (INIS)

Barenghi, C F; Donnelly, R J

2009-01-01

The study of vortex rings has been pursued for decades and is a particularly difficult subject. However, the discovery of quantized vortex rings in superfluid helium has greatly increased interest in vortex rings with very thin cores. While rapid progress has been made in the simulation of quantized vortex rings, there has not been comparable progress in laboratory studies of vortex rings in a viscous fluid such as water. This article overviews the history and current frontiers of classical and quantum vortex rings. After introducing the classical results, this review discusses thin-cored vortex rings in superfluid helium in section 2, and recent progress in understanding vortex rings of very thin cores propagating in water in section 3. (invited paper)

Selective Tree-ring Models: A Novel Method for Reconstructing Streamflow Using Tree Rings

Science.gov (United States)

Foard, M. B.; Nelson, A. S.; Harley, G. L.

2017-12-01

Surface water is among the most instrumental and vulnerable resources in the Northwest United States (NW). Recent observations show that overall water quantity is declining in streams across the region, while extreme flooding events occur more frequently. Historical streamflow models inform probabilities of extreme flow events (flood or drought) by describing frequency and duration of past events. There are numerous examples of tree-rings being utilized to reconstruct streamflow in the NW. These models confirm that tree-rings are highly accurate at predicting streamflow, however there are many nuances that limit their applicability through time and space. For example, most models predict streamflow from hydrologically altered rivers (e.g. dammed, channelized) which may hinder our ability to predict natural prehistoric flow. They also have a tendency to over/under-predict extreme flow events. Moreover, they often neglect to capture the changing relationships between tree-growth and streamflow over time and space. To address these limitations, we utilized national tree-ring and streamflow archives to investigate the relationships between the growth of multiple coniferous species and free-flowing streams across the NW using novel species-and site-specific streamflow models - a term we coined"selective tree-ring models." Correlation function analysis and regression modeling were used to evaluate the strengths and directions of the flow-growth relationships. Species with significant relationships in the same direction were identified as strong candidates for selective models. Temporal and spatial patterns of these relationships were examined using running correlations and inverse distance weighting interpolation, respectively. Our early results indicate that (1) species adapted to extreme climates (e.g. hot-dry, cold-wet) exhibit the most consistent relationships across space, (2) these relationships weaken in locations with mild climatic variability, and (3) some

Laparoscopic appendicectomy using endo-ring applicator and fallope rings

International Nuclear Information System (INIS)

Ali, Iyoob V; Maliekkal, Joji I

2009-01-01

Wider adoption of laparoscopic appendicectomy (LA) is limited by problems in securing the appendiceal base as well as the cost and the duration compared with the open procedure. The objective of this study was to assess the feasibility and efficacy of a new method for securing the appendiceal base in LA, so as to make the entire procedure simpler and cheaper, and hence, more popular. Twenty-five patients who were candidates for appendicectomy (emergency as well as elective) and willing for the laparoscopic procedure were selected for this study. Ports used were 10 mm at the umbilicus, 5 mm at the lower right iliac fossa, and 10 mm at the left iliac fossa. Extremely friable, ruptured, or turgid organs of diameters larger than 8 mm were excluded from the study. The mesoappendix was divided close to the appendix by diathermy. Fallope rings were applied to the appendiceal base using a special ring applicator, and the appendix was divided and extracted through the lumen of the applicator. The procedure was successful in 23 (92%) cases, and the mean duration of the procedure was 20 minutes (15-32 minutes). There were no procedural complications seen during a median follow-up of two weeks. The equipment and rings were cheaper when compared with that of the standard methods of securing the base of the appendix. LA using fallope rings is a safe, simple, easy-to-learn, and economically viable method. (author)

Status of the PEP-II B-factory high energy ring

International Nuclear Information System (INIS)

Wienands, U.; Reuter, E.; Bellomo, P.; Daly, E.; Fisher, A.; Gracia, J.; Kulikov, A.; Kurita, N.; Pietryka, M.; Seeman, J.T.; Taylor; Belser, C.; Bertolini, L.; Mugge, M.; Swan, J.

1996-01-01

The 9 GeV High Energy Ring (HER) of the PEP-II B Factory is an electron storage ring under construction at SLAC. Significant progress has been made in the last year on all systems. As of mid 1996, all 192 dipoles have been installed, with installation of the quadrupoles underway. The vacuum system, for design currents up to 3 A average, is in production using a recently commissioned e-beam welder. Beam instrumentation systems are being fabricated. The interaction region will bring the HER beam into collision with the 3 GeV beam of the Low Energy Ring; design of this section of the HER is in an advanced stage. 8 refs., 3 figs., 1 tab

Rotationally asymmetric multifocal IOL implantation with and without capsular tension ring: refractive and visual outcomes and intraocular optical performance.

Science.gov (United States)

Alió, Jorge L; Plaza-Puche, Ana B; Piñero, David P

2012-04-01

To ascertain whether the refractive, visual, and intraocular optical quality outcomes of a rotationally asymmetric multifocal intraocular lens (IOL) are enhanced by the use of a capsular tension ring. Ninety consecutive eyes from 53 patients (age range: 36 to 82 years) were divided into two groups: the no ring group comprised 43 eyes implanted with the multifocal rotationally asymmetric Lentis Mplus LS-312 (Oculentis GmbH) without a capsular tension ring; and the ring group comprised 47 eyes with the same IOL with a capsular tension ring. Distance and near visual acuity and refractive outcomes were evaluated pre- and postoperatively. Contrast sensitivity, intraocular aberrations, and defocus curve were evaluated postoperatively. Significant postoperative differences between groups were found in sphere, spherical equivalent refraction, and near addition (P<.02). Regarding defocus curve, significantly better visual acuity was present in eyes with the capsular tension ring for intermediate vision conditions (P<.05). Intraocular aberrometry did not differ significantly between groups (P<.09). Refractive predictability and intermediate visual outcomes with the Lentis Mplus LS-312 IOL improved significantly when implanted in combination with a capsular tension ring. Copyright 2012, SLACK Incorporated.

SMARANDACHE NON-ASSOCIATIVE RINGS

OpenAIRE

Vasantha, Kandasamy

2002-01-01

An associative ring is just realized or built using reals or complex; finite or infinite by defining two binary operations on it. But on the contrary when we want to define or study or even introduce a non-associative ring we need two separate algebraic structures say a commutative ring with 1 (or a field) together with a loop or a groupoid or a vector space or a linear algebra. The two non-associative well-known algebras viz. Lie algebras and Jordan algebras are mainly built using a vecto...

Heavy ion storage rings

International Nuclear Information System (INIS)

Schuch, R.

1987-01-01

A brief overview of synchrotron storage rings for heavy ions, which are presently under construction in different accelerator laboratories is given. Ions ranging from protons up to uranium ions at MeV/nucleon energies will be injected into these rings using multiturn injection from the accelerators available or being built in these laboratories. After injection, it is planned to cool the phase space distribution of the ions by merging them with cold electron beams or laser beams, or by using stochastic cooling. Some atomic physics experiments planned for these rings are presented. 35 refs

Non-Linear Rheological Properties and Neutron Scattering Investigation on Dilute Ring-Linear Blends

DEFF Research Database (Denmark)

Pyckhout-Hintzen, W.; Bras, A.R.; Wischnewski, A.

in a filament stretching rheometer, followed by quenching, strong anisotropic scattering patterns were obtained which were described by affinely deformed rings which function as giant, polymeric chemical crosslinks or sliplinks and more or less isotropic topological contributions from the entangling...... with interpenetrating linear chains. At the same time the non-linear rheological and mechanical data fit to a non-affine slip-tube model as for moderately crosslinked networks and to interchain pressure models or a modified non-linear Doi-Edwards description for the observed strain hardening during the extensional...

Tricuspid annuloplasty with the MC3 ring and septal plication technique.

Science.gov (United States)

Isomura, Tadashi; Hirota, Masanori; Hoshino, Joji; Fukada, Yasuhisa; Kondo, Taichi; Takahashi, Yu

2015-01-01

Functional tricuspid regurgitation is caused by annular dilation mainly in the posterior annulus. However, ring annuloplasty does not always prevent the recurrence of tricuspid regurgitation due to dilation of the septal annulus. We developed a septal plication technique with a 3-dimensional MC3 ring. Between 2006 and 2011, 76 patients (male/female 30/46; mean age 68 ± 11 years) with functional tricuspid regurgitation received tricuspid ring annuloplasty. After placement of the annular sutures, the 3 commissural ring portions were fixed on the equivalent commissures to plicate the anterior and posterior annulus. The end of the septal ring portion was fixed at the optimal annular position to obtain minimal tricuspid regurgitation. All patients were followed-up for a mean of 47 ± 18 months; the longest duration was 79 months. Although there was no operative death, one patient died of sepsis during hospitalization (hospital mortality 1.3%). After implantation of the MC3 ring (mean size 31.0 ± 3.3 mm), additional edge-to-edge sutures were required for minor leakage in 5 (7%) patients. The degree of tricuspid regurgitation was significantly reduced at discharge (0.5 ± 0.6) and midterm (0.6 ± 0.6) compared to 2.5 ± 0.7 before the operation (p tricuspid ring annuloplasty with a 3-dimensional MC3 ring. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Moving ring reactor 'Karin-1'

International Nuclear Information System (INIS)

1983-12-01

The conceptual design of a moving ring reactor ''Karin-1'' has been carried out to advance fusion system design, to clarify the research and development problems, and to decide their priority. In order to attain these objectives, a D-T reactor with tritium breeding blanket is designed, a commercial reactor with net power output of 500 MWe is designed, the compatibility of plasma physics with fusion engineering is demonstrated, and some other guideline is indicated. A moving ring reactor is composed mainly of three parts. In the first formation section, a plasma ring is formed and heated up to ignition temperature. The plasma ring of compact torus is transported from the formation section through the next burning section to generate fusion power. Then the plasma ring moves into the last recovery section, and the energy and particles of the plasma ring are recovered. The outline of a moving ring reactor ''Karin-1'' is described. As a candidate material for the first wall, SiC was adopted to reduce the MHD effect and to minimize the interaction with neutrons and charged particles. The thin metal lining was applied to the SiC surface to solve the problem of the compatibility with lithium blanket. Plasma physics, the engineering aspect and the items of research and development are described. (Kako, I.)

Tinkering at the main-ring lattice

Energy Technology Data Exchange (ETDEWEB)

Ohnuma, S.

1982-08-23

To improve production of usable antiprotons using the proton beam from the main ring and the lossless injection of cooled antiprotons into the main ring, modifications of the main ring lattice are recommended.

The ring plus project: safety and acceptability of vaginal rings that protect women from unintended pregnancy

OpenAIRE

Schurmans, C?line; De Baetselier, Irith; Kestelyn, Evelyne; Jespers, Vicky; Delvaux, Th?r?se; Agaba, Stephen K; van Loen, Harry; Menten, Joris; van de Wijgert, Janneke; Crucitti, Tania

2015-01-01

Background Research is ongoing to develop multipurpose vaginal rings to be used continuously for contraception and to prevent Human Immunodeficiency Virus (HIV) infection. Contraceptive vaginal rings (CVRs) are available in a number of countries and are most of the time used intermittently i.e. three weeks out of a 4-week cycle. Efficacy trials with a dapivirine-containing vaginal ring for HIV prevention are ongoing and plans to develop multi-purpose vaginal rings for prevention of both HIV a...

Suppression of coffee ring: (Particle) size matters

Science.gov (United States)

Bansal, Lalit; Seth, Pranjal; Murugappan, Bhubesh; Basu, Saptarshi

2018-05-01

Coffee ring patterns in drying sessile droplets are undesirable in various practical applications. Here, we experimentally demonstrate that on hydrophobic substrates, the coffee ring can be suppressed just by increasing the particle diameter. Particles with larger size flocculate within the evaporation timescale, leading to a significant gravimetric settling (for Pe > 1) triggering a uniform deposit. Interestingly, the transition to a uniform deposit is found to be independent of the internal flow field and substrate properties. Flocculation of particles also alters the particle packing at the nanoscale resulting in order to disorder transitions. In this letter, we exhibit a physical exposition on how particle size affects morphodynamics of the droplet drying at macro-nano length scales.

Pyrimidine-pyridine ring interconversion

NARCIS (Netherlands)

Plas, van der H.C.

2003-01-01

This chapter discusses the pyrimidine-to-pyridine ring transformation and pyridine-to-pyrimidine ring transformation. In nucleophile-induced pyrimidine-to-pyridine rearrangements, two types of reactions can be distinguished depending on the structure of the nucleophile: (1) reactions in which the

Electron beam cooling at a magnetic storage ring, TARN II, and an electrostatic storage ring

International Nuclear Information System (INIS)

Tanabe, Tetsumi

2006-01-01

At the High Energy Accelerator Research Organization (KEK), a magnetic storage ring, TARN II, with an electron cooler was operated from 1989 to 1999, while an electrostatic storage ring with a small electron cooler has been operational since 2000. In this paper, the electron cooling at TARN II and the electrostatic storage ring is described. (author)

Leapfrogging of multiple coaxial viscous vortex rings

International Nuclear Information System (INIS)

Cheng, M.; Lou, J.; Lim, T. T.

2015-01-01

A recent theoretical study [Borisov, Kilin, and Mamaev, “The dynamics of vortex rings: Leapfrogging, choreographies and the stability problem,” Regular Chaotic Dyn. 18, 33 (2013); Borisov et al., “The dynamics of vortex rings: Leapfrogging in an ideal and viscous fluid,” Fluid Dyn. Res. 46, 031415 (2014)] shows that when three coaxial vortex rings travel in the same direction in an incompressible ideal fluid, each of the vortex rings alternately slips through (or leapfrogs) the other two ahead. Here, we use a lattice Boltzmann method to simulate viscous vortex rings with an identical initial circulation, radius, and separation distance with the aim of studying how viscous effect influences the outcomes of the leapfrogging process. For the case of two identical vortex rings, our computation shows that leapfrogging can be achieved only under certain favorable conditions, which depend on Reynolds number, vortex core size, and initial separation distance between the two rings. For the case of three coaxial vortex rings, the result differs from the inviscid model and shows that the second vortex ring always slips through the leading ring first, followed by the third ring slipping through the other two ahead. A simple physical model is proposed to explain the observed behavior

Redox shuttles having an aromatic ring fused to a 1,1,4,4-tetrasubstituted cyclohexane ring

Science.gov (United States)

Weng, Wei; Zhang, Zhengcheng; Amine, Khalil

2015-12-01

An electrolyte includes an alkali metal salt; an aprotic solvent; and a redox shuttle additive including an aromatic compound having at least one aromatic ring fused with at least one non-aromatic ring, the aromatic ring having two or more oxygen or phosphorus-containing substituents.

Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

Energy Technology Data Exchange (ETDEWEB)

Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Carrington, P. J. [Department of Electronic and Electrical Engineering, University College London, London (United Kingdom); Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2014-07-28

The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

Heating of energetic electrons and ELMO ring formation in symmetric mirror facility

International Nuclear Information System (INIS)

Quon, B.H.; Dandl, R.A.; Lazar, N.H.; Wuerker, R.F.

1982-01-01

The spatial structure of the high beta, hot-electron ECH plasma, (ELMO Ring), has been studied by using a Hall probe array diagnostic system which measures the diamagnetic field of the hot electron plasma in a large number of spatial locations. The steady state pressure profile obtained using a two-gaussian geometric model that best fits the measurements is found to peak at the mirror midplane near the vacuum field second harmonic resonant point. The radial width of the ring is typically 4 to 7 cm, and the axial length extends significantly beyond the second harmonic resonance zone of the total magnetic field. The radial thickness and the Ring beta are increased by multiple frequency ECH. The electron ring is observed to evolve from a sloshing-like turning point distribution which was observed in the early times following a microwave turnon, demonstrating stochastic processes involved in ELMO Ring formation

Bunch lengthening in the SLC [Stanford Linear Collider] damping rings

International Nuclear Information System (INIS)

Bane, K.L.F.

1990-02-01

A high level of current dependent bunch lengthening has been observed on the North damping ring of the Stanford Linear Collider (SLC). At currents of 3 x 10 10 this behavior does not appear to degrade the machine's performance significantly. However, at the higher currents that are envisioned for the future one fears that its performance could be greatly degraded due to the phenomenon of bunch lengthening. This was the motivation for the work described in this paper. In this paper we calculate the longitudinal impedance of the damping ring vacuum chamber. More specifically, in this paper we find the response function of the ring to a short Gaussian bunch, which we call the Green function wake. In addition, we try to estimate the relative importance of the different vacuum chamber objects, in order to see how we might reduce the ring impedance. This paper also describes bunch length measurements performed on the North damping ring. We use the Green function wake, discussed above, to compute the bunch lengthening. Then we compare these results with those obtained from the measurements. In addition, we calculate the current dependence of the tune distribution

Simulation of the Initial 3-D Instability of an Impacting Drop Vortex Ring

DEFF Research Database (Denmark)

Sigurdson, Lorenz; Wiwchar, Justin; Walther, Jens Honore

2013-01-01

, a Rayleigh centrifugal instability, or a vortex breakdown-type instability. Simulations which simply have a perturbed solitary ring result in an instability similar to that seen experimentally. Waviness of the core which would be expected from a Widnall instability is not visible. Adding an opposite......-signed secondary vortex ring or an image vortex ring to the initial conditions, to trigger a Rayleigh or breakdown respectively, does not appear to significantly change the instability from what is seen with a solitary ring. This suggests that a Rayleigh or vortex breakdown-type instability are not likely at work......Computational vortex particle method simulations of a perturbed vortex ring are performed to recreate and understand the instability seen in impacting water drop experiments. Three fundamentally different initial vorticity distributions are used to attempt to trigger a Widnall instability...

Interaction of Vortex Ring with Cutting Plate

Science.gov (United States)

Musta, Mustafa

2015-11-01

The interaction of a vortex ring impinging on a thin cutting plate was made experimentally using Volumetric 3-component Velocitmetry (v3v) technique. The vortex rings were generated with piston-cylinder vortex ring generator using piston stroke-to-diameter ratios and Re at 2-3 and 1500 - 3000, respectively. The cutting of vortex rings below center line leads to the formation of secondary vortices on each side of the plate which is look like two vortex rings, and a third vortex ring propagates further downstream in the direction of the initial vortex ring, which is previously showed by flow visualization study of Weigand (1993) and called ``trifurcation''. Trifurcation is very sensitive to the initial Reynolds number and the position of the plate with respect to the vortex ring generator pipe. The present work seeks more detailed investigation on the trifurcation using V3V technique. Conditions for the formation of trifurcation is analyzed and compared with Weigand (1993). The formed secondary vortex rings and the propagation of initial vortex ring in the downstream of the plate are analyzed by calculating their circulation, energy and trajectories.

Truncated exponential-rigid-rotor model for strong electron and ion rings

International Nuclear Information System (INIS)

Larrabee, D.A.; Lovelace, R.V.; Fleischmann, H.H.

1979-01-01

A comprehensive study of exponential-rigid-rotor equilibria for strong electron and ion rings indicates the presence of a sizeable percentage of untrapped particles in all equilibria with aspect-ratios R/a approximately <4. Such aspect-ratios are required in fusion-relevant rings. Significant changes in the equilibria are observed when untrapped particles are excluded by the use of a truncated exponential-rigid-rotor distribution function. (author)

Magnetic ring for stripping enhancement

International Nuclear Information System (INIS)

Selph, F.

1992-10-01

A ring designed to recycle ions through a stripping medium offers the possibility for increasing output of the desired charge state by up to 4x. This could be a very important component of a Radioactive Nuclear Beam Facility. In order for such a ring to work effectively it must satisfy certain design conditions. These include achromaticity at the stripper, a dispersed region for an extraction magnet, and a number of first and higher order optics constraints which are necessary to insure that the beam emittance is not degraded unduly by the ring. An example is given of a candidate design of a stripping ring

Acceleration of magnetized plasma rings

International Nuclear Information System (INIS)

Hartman, D.; Eddleman, J.; Hammer, J.H.

1982-01-01

One scheme is considered, acceleration of a ring between coaxial electrodes by a B/sub theta/ field as in a coaxial rail-gun. If the electrodes are conical, a ring accelerated towards the apex of the cone undergoes self-similar compression (focussing) during acceleration. Because the allowable acceleration force F/sub a/ = kappa U/sub m//R (kappa - 2 , the accelerating distance for conical electrodes is considerably shortened over that required for coaxial electrodes. In either case however, since the accelerating flux can expand as the ring moves, most of the accelerating field energy can be converted into kinetic energy of the ring leading to high efficiency

Origin of strain-induced resonances in flexible terahertz metamaterials

International Nuclear Information System (INIS)

Sun Xiu-Yun; Li Xiao-Ning; Xu Hua; Liang Xian-Ting; Zheng Li-Ren; Zhang Xian-Peng; Lu Yue-Hui; Song Wei-Jie; Lee, Young-Pak; Rhee, Joo-Yull

2016-01-01

Two types of flexible terahertz metamaterials were fabricated on polyethylene naphthalate (PEN) substrates. The unit cell of one type consists of two identical split-ring resonators (SRRs) that are arranged face-to-face (i.e., FlexMetaF); the unit cell of the other type has nothing different but is arranged back-to-back (i.e., FlexMetaB). FlexMetaF and FlexMetaB illustrate the similar transmission dips under zero strain because the excitation of fundamental inductive–capacitive (LC) resonance is mainly dependent on the geometric structure of individual SRR. However, if a gradually variant strain is applied to bend FlexMetaF and FlexMetaB, the new resonant peaks appear: in the case of FlexMetaF, the peaks are located at the lower frequencies; in the case of FlexMetaB, the peaks appear at the frequencies adjacent to the LC resonance. The origin and evolution of strain-induced resonances are studied. The origin is ascribed to the detuning effect and the different responses to strain from FlexMetaF and FlexMetaB are associated with the coupling effect. These findings may improve the understanding on flexible terahertz metamaterials and benefit their applications in flexible or curved devices. (paper)

Neutron and ultrasonic determination of residual stress in an aluminum ring-plug

International Nuclear Information System (INIS)

Prask, H.J.; Gnaeupel-Herold, T.; Clark, A.V.; Hehman, C.S.; Nguyen, T.N.

2000-01-01

Stress is a principal cause of material failure. This has been a well-recognized problem for decades, yet--in general--neutron diffraction remains the only way to measure sub-surface residual stresses without destroying the component. A field-portable ultrasonic strain-meter is being developed at NIST (Boulder) to determine residual stresses in engineering specimens, nondestructively. To test this and other techniques an array of stress-measurement standards are being prepared. These will be characterized by neutron diffraction and then used to evaluate, quantitatively, the potential of new methods. The first standard specimen produced for this purpose is a large shrink-fit ring-plug of 2024 aluminum (305 mm OD, 25.4 mm thick, 101.6 mm diameter plug). Because of large grain size, a sample-rotation averaging technique was developed to make reliable neutron measurements possible. A comparison of the neutron diffraction and ultrasonic results for this specimen will be presented, along with strain gauge results

A first course in noncommutative rings

CERN Document Server

Lam, T Y

2001-01-01

A First Course in Noncommutative Rings, an outgrowth of the author's lectures at the University of California at Berkeley, is intended as a textbook for a one-semester course in basic ring theory. The material covered includes the Wedderburn-Artin theory of semisimple rings, Jacobson's theory of the radical, representation theory of groups and algebras, prime and semiprime rings, local and semilocal rings, perfect and semiperfect rings, etc. By aiming the level of writing at the novice rather than the connoisseur and by stressing th the role of examples and motivation, the author has produced a text that is suitable not only for use in a graduate course, but also for self- study in the subject by interested graduate students. More than 400 exercises testing the understanding of the general theory in the text are included in this new edition.

Survey and alignment of photon factory storage ring at KEK

International Nuclear Information System (INIS)

Araki, A.; Honjo, I.; Katoh, M.; Kamiya, Y.; Kihara, M.

1987-01-01

The heights of the magnets for both the ring and the beam transport line (BT-line) have been periodically measured at the Photon Factory. The accumulated data showed that the ring was considerably declined due to the construction of the large experimental hall and the tunnel of the TRISTAN project, and that the BT-line also sank several centimeters at some locations. These displacements of the magnets produce a significantly large closed orbit distortion and the vertical dispersion

Design of Piston Ring Friction Tester Apparatus

DEFF Research Database (Denmark)

Klit, Peder

2006-01-01

One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. Piston rings operate in three different lubrication regimes and the theoretical models should be capable to describe this. A very important condition for describing the frictio......One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. Piston rings operate in three different lubrication regimes and the theoretical models should be capable to describe this. A very important condition for describing...... the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount...... available is reflected in the friction absorbed in the bearing. The following properties will be measured: Oil fillm thickness - along liner (axial variation), oil film thickness - along piston ring (circumferential variation), piston tilt, temperature of piston rings and liner, pressure at piston lands...

Study for ILC Damping Ring at KEKB

Energy Technology Data Exchange (ETDEWEB)

Flanagan, J.W.; Fukuma, H.; Kanazawa, K.I.; Koiso, H.; Masuzawa, M.; Ohmi, Kazuhito; Ohnishi, Y.; Oide, Katsunobu; Suetsugu, Y.; Tobiyama, M.; /KEK, Tsukuba; Pivi, M.; /SLAC

2011-11-04

ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.

Fiber Optic Strain Sensor for Planetary Gear Diagnostics

Science.gov (United States)

Kiddy, Jason S.; Lewicki, David G.; LaBerge, Kelsen E.; Ehinger, Ryan T.; Fetty, Jason

2011-01-01

This paper presents a new sensing approach for helicopter damage detection in the planetary stage of a helicopter transmission based on a fiber optic strain sensor array. Complete helicopter transmission damage detection has proven itself a difficult task due to the complex geometry of the planetary reduction stage. The crowded and complex nature of the gearbox interior does not allow for attachment of sensors within the rotating frame. Hence, traditional vibration-based diagnostics are instead based on measurements from externally mounted sensors, typically accelerometers, fixed to the gearbox exterior. However, this type of sensor is susceptible to a number of external disturbances that can corrupt the data, leading to false positives or missed detection of potentially catastrophic faults. Fiber optic strain sensors represent an appealing alternative to the accelerometer. Their small size and multiplexibility allows for potentially greater sensing resolution and accuracy, as well as redundancy, when employed as an array of sensors. The work presented in this paper is focused on the detection of gear damage in the planetary stage of a helicopter transmission using a fiber optic strain sensor band. The sensor band includes an array of 13 strain sensors, and is mounted on the ring gear of a Bell Helicopter OH-58C transmission. Data collected from the sensor array is compared to accelerometer data, and the damage detection results are presented

Planetary ring systems properties, structures, and evolution

CERN Document Server

Murray, Carl D

2018-01-01

Planetary rings are among the most intriguing structures of our solar system and have fascinated generations of astronomers. Collating emerging knowledge in the field, this volume reviews our current understanding of ring systems with reference to the rings of Saturn, Uranus, Neptune, and more. Written by leading experts, the history of ring research and the basics of ring–particle orbits is followed by a review of the known planetary ring systems. All aspects of ring system science are described in detail, including specific dynamical processes, types of structures, thermal properties and their origins, and investigations using computer simulations and laboratory experiments. The concluding chapters discuss the prospects of future missions to planetary rings, the ways in which ring science informs and is informed by the study of other astrophysical disks, and a perspective on the field's future. Researchers of all levels will benefit from this thorough and engaging presentation.

Longitudinal beam instability due to the ring impedance at KEK's accelerator test facility damping ring

International Nuclear Information System (INIS)

Kim, Eun-San

2003-01-01

This paper shows the results of a numerical study of the impedance in the Accelerator Test Facility damping ring. The longitudinal impedance in the damping ring is shown to be inductive. It is shown that the total impedance |Z || /n| is 0.23 Ω and the inductance is L = 14 nH. In the extremely low emittance beam of the damping ring, bunch lengthening is caused by both the effects of potential-well distortion and intra-beam scattering. In this paper, the bunch-lengthening due to the ring impedance is numerically investigated, and the result shows qualitative agreement with the result of an analysis performed using the bunch-length measurement. With the calculated longitudinal impedance, the instability threshold in the damping ring is estimated to be a bunch population of 3.3 x 10 10 by using both a Vlasov equation approach and a multi-particle tracking method.

Lord of the Rings - Return of the King: Swift-XRT observations of dust scattering rings around V404 Cygni

Science.gov (United States)

Beardmore, A. P.; Willingale, R.; Kuulkers, E.; Altamirano, D.; Motta, S. E.; Osborne, J. P.; Page, K. L.; Sivakoff, G. R.

2016-10-01

On 2015 June 15, the black hole X-ray binary V404 Cygni went into outburst, exhibiting extreme X-ray variability which culminated in a final flare on June 26. Over the following days, the Swift-X-ray Telescope detected a series of bright rings, comprising five main components that expanded and faded with time, caused by X-rays scattered from the otherwise unobservable dust layers in the interstellar medium in the direction of the source. Simple geometrical modelling of the rings' angular evolution reveals that they have a common temporal origin, coincident with the final, brightest flare seen by INTEGRAL's JEM X-1, which reached a 3-10 keV flux of ˜25 Crab. The high quality of the data allows the dust properties and density distribution along the line of sight to the source to be estimated. Using the Rayleigh-Gans approximation for the dust scattering cross-section and a power-law distribution of grain sizes a, ∝ a-q, the average dust emission is well modelled by q = 3.90^{+0.09}_{-0.08} and maximum grain size of a_+ = 0.147^{+0.024}_{-0.004} { μ m}, though significant variations in q are seen between the rings. The recovered dust density distribution shows five peaks associated with the dense sheets responsible for the rings at distances ranging from 1.19 to 2.13 kpc, with thicknesses of ˜40-80 pc and a maximum density occurring at the location of the nearest sheet. We find a dust column density of Ndust ≈ (2.0-2.5) × 1011 cm-2, consistent with the optical extinction to the source. Comparison of the inner rings' azimuthal X-ray evolution with archival Wide-field Infrared Survey Explorer mid-IR data suggests that the second most distant ring follows the general IR emission trend, which increases in brightness towards the Galactic north side of the source.

"Ring" in the solo child singing voice.

Science.gov (United States)

Howard, David M; Williams, Jenevora; Herbst, Christian T

2014-03-01

Listeners often describe the voices of solo child singers as being "pure" or "clear"; these terms would suggest that the voice is not only pleasant but also clearly audible. The audibility or clarity could be attributed to the presence of high-frequency partials in the sound: a "brightness" or "ring." This article aims to investigate spectrally the acoustic nature of this ring phenomenon in children's solo voices, and in particular, relating it to their "nonring" production. Additionally, this is set in the context of establishing to what extent, if any, the spectral characteristics of ring are shared with those of the singer's formant cluster associated with professional adult opera singers in the 2.5-3.5kHz region. A group of child solo singers, acknowledged as outstanding by a singing teacher who specializes in teaching professional child singers, were recorded in a major UK concert hall performing Come unto him, all ye that labour, from the aria He shall feed his flock from The Messiah by GF Handel. Their singing was accompanied by a recording of a piano played through in-ear headphones. Sound pressure recordings were made from well within the critical distance in the hall. The singers were observed to produce notes with and without ring, and these recordings were analyzed in the frequency domain to investigate their spectra. The results indicate that there is evidence to suggest that ring in child solo singers is carried in two areas of the output spectrum: first in the singer's formant cluster region, centered around 4kHz, which is more than 1000Hz higher than what is observed in adults; and second in the region around 7.5-11kHz where a significant strengthening of harmonic presence is observed. A perceptual test has been carried out demonstrating that 94% of 62 listeners label a synthesized version of the calculated overall average ring spectrum for all subjects as having ring when compared with a synthesized version of the calculated overall average nonring

Evaluation of shrinkage and cracking in concrete of ring test by acoustic emission method

Science.gov (United States)

Watanabe, Takeshi; Hashimoto, Chikanori

2015-03-01

Drying shrinkage of concrete is one of the typical problems related to reduce durability and defilation of concrete structures. Lime stone, expansive additive and low-heat Portland cement are used to reduce drying shrinkage in Japan. Drying shrinkage is commonly evaluated by methods of measurement for length change of mortar and concrete. In these methods, there is detected strain due to drying shrinkage of free body, although visible cracking does not occur. In this study, the ring test was employed to detect strain and age cracking of concrete. The acoustic emission (AE) method was adopted to detect micro cracking due to shrinkage. It was recognized that in concrete using lime stone, expansive additive and low-heat Portland cement are effective to decrease drying shrinkage and visible cracking. Micro cracking due to shrinkage of this concrete was detected and evaluated by the AE method.

Nonlinear analysis of ring oscillator circuits

KAUST Repository

Ge, Xiaoqing

2010-06-01

Using nonlinear systems techniques, we analyze the stability properties and synchronization conditions for ring oscillator circuits, which are essential building blocks in digital systems. By making use of its cyclic structure, we investigate local and global stability properties of an n-stage ring oscillator. We present a sufficient condition for global asymptotic stability of the origin and obtain necessity if the ring oscillator consists of identical inverter elements. We then give a synchronization condition for identical interconnected ring oscillators.

Nonlinear analysis of ring oscillator circuits

KAUST Repository

Ge, Xiaoqing; Arcak, Murat; Salama, Khaled N.

2010-01-01

Using nonlinear systems techniques, we analyze the stability properties and synchronization conditions for ring oscillator circuits, which are essential building blocks in digital systems. By making use of its cyclic structure, we investigate local and global stability properties of an n-stage ring oscillator. We present a sufficient condition for global asymptotic stability of the origin and obtain necessity if the ring oscillator consists of identical inverter elements. We then give a synchronization condition for identical interconnected ring oscillators.

Quality Assurance Project Plan for Verification of Sediment Ecotoxicity Assessment Ring(SEA Ring)

Science.gov (United States)

The objective of the verification is to test the efficacy and ability of the Sediment Ecotoxicity Assessment Ring (SEA Ring) to evaluate the toxicity of contaminants in the sediment, at the sediment-water interface, and WC to organisms that live in those respective environments.

Dynamical Evolution of Ring-Satellite Systems

Science.gov (United States)

Ohtsuki, Keiji

2005-01-01

The goal of this research was to understand dynamical processes related to the evolution of size distribution of particles in planetary rings and application of theoretical results to explain features in the present rings of giant planets. We studied velocity evolution and accretion rates of ring particles in the Roche zone. We developed a new numerical code for the evolution of ring particle size distribution, which takes into account the above results for particle velocity evolution and accretion rates. We also studied radial diffusion rate of ring particles due to inelastic collisions and gravitational encounters. Many of these results can be also applied to dynamical evolution of a planetesimal disk. Finally, we studied rotation rates of moonlets and particles in planetary rings, which would influence the accretional evolution of these bodies. We describe our key accomplishments during the past three years in more detail in the following.

Cosmic rings from colliding galaxies

Energy Technology Data Exchange (ETDEWEB)

Mitton, S

1976-11-18

Research on two ring galaxies has led to the proposal of an interaction model to account for the rings. It is envisaged that this class of galaxy is created when a compact galaxy crashes through the disc of a spiral galaxy. The results of a spectroscopic investigation of the galaxy known as the Cartwheel and of another ring galaxy 11 NZ 4 are discussed. The general picture of ring galaxies which emerges from these studies of a massive starry nucleus with a necklace of emitting gas and some spokes and along the spin axis of the wheel a small companion galaxy that is devoid of interstellar gas. An explanation of these properties is considered.

Tracheal ceramic rings for tracheomalacia: a review after 17 years.

Science.gov (United States)

Göbel, Gyula; Karaiskaki, Niki; Gerlinger, Imre; Mann, Wolf J

2007-10-01

Despite different support techniques, the surgical management of tracheomalacia is still a challenging problem. Satisfactory results after internal stenting are above 80%, whereas, when performing external stenting using biocompatible ceramic rings, results are reported at over 90%. The purpose of this study was to examine the efficiency of surgical treatment in patients with segmentary tracheomalacia using external ceramic ring grafts. In this retrospective study, we collected data from 12 patients who underwent surgery during the last 17 years for symptomatic segmentary tracheomalacia by use of biocompatible aluminum-oxide ceramic rings. All except one patient had undergone previous tracheostomy, six had a history of long-term intubation, two had previous trauma, and two patients had previous cancer treatment including radiotherapy. One of the patients still had an existing tracheostoma, which was closed when a ceramic ring was implanted. Tracheal wall collapse with pseudoglottis formation or flattened anterior-posterior tracheal diameter was documented with fiberoscopy at rest, and both pre- and postoperative airway resistance measurements were performed in all 12 patients using a spirometer. After malacic segments were found to be expandable using rigid tracheoscopy while the patient was under general anesthesia, preparation of the trachea was performed using a midline vertical incision in the neck. Subsequently, the malacic trachea was expanded by placing and suturing proper-sized ceramic ring(s) around it. In all patients, surgical expansion of the malacic segment using ceramic rings was successfully carried out without major complications while inspiratory stridor was resolved. Airway resistance decreased significantly from an average of 0.62 to 0.385 kPascal. Although the results of applying internal tracheal stents are encouraging, complications such as stent migration, granulation tissue and fistula formation, and mucociliary transport arrest are possible

Indolyl aryl sulfones as HIV-1 non-nucleoside reverse transcriptase inhibitors: role of two halogen atoms at the indole ring in developing new analogues with improved antiviral activity.

Science.gov (United States)

Regina, Giuseppe La; Coluccia, Antonio; Piscitelli, Francesco; Bergamini, Alberto; Sinistro, Anna; Cavazza, Antonella; Maga, Giovanni; Samuele, Alberta; Zanoli, Samantha; Novellino, Ettore; Artico, Marino; Silvestri, Romano

2007-10-04

Indolyl aryl sulfones bearing the 4,5-difluoro (10) or 5-chloro-4-fluoro (16) substitution pattern at the indole ring were potent inhibitors of HIV-1 WT and the NNRTI-resistant strains Y181C and K103N-Y181C. These compounds were highly effective against the 112 and the AB1 strains in lymphocytes and inhibited at nanomolar concentration the multiplication of the IIIBBa-L strain in macrophages. Compound 16 was exceptionally potent against RT WT and RTs carrying the K103N, Y181I, and L100I mutations.

Applicability of a particularly simple model to nonlinear elasticity of slide-ring gels with movable cross-links as revealed by unequal biaxial deformation.

Science.gov (United States)

Kondo, Yuuki; Urayama, Kenji; Kidowaki, Masatoshi; Mayumi, Koichi; Takigawa, Toshikazu; Ito, Kohzo

2014-10-07

The strain energy density function (F) of the polyrotaxane-based slide-ring (SR) gels with movable cross-links along the network strands is characterized by unequal biaxial stretching which can achieve various types of deformation. The SR gels as prepared without any post-preparation complication exhibit considerably smaller values of the ratio of the stresses (σy/σx) in the stretched (x) and constrained (y) directions in planar extension than classical chemical gels with heterogeneous and nearly homogeneous network structures do. This feature of the SR gels leads to the peculiar characteristic that the strain energy density function (F) has no explicit cross term of strains in different directions, which is in contrast to F with explicit strain cross terms for most chemical gels and elastomers. The biaxial stress-strain data of the SR gels are successfully described by F of the Gent model with only two parameters (small-strain shear modulus and a parameter representing ultimate elongation), which introduces the finite extensibility effect into the neo-Hookean model with no explicit cross term of strain. The biaxial data of the deswollen SR gels examined in previous study, which underwent a considerable reduction in volume from the preparation state, are also well described by the Gent model, which is in contrast to the case of the classical chemical gels that the stress-strain relations before and after large deswelling are not described by a common type of F due to a significant degree of collapse of the network strands in the deswollen state. These intriguing features of nonlinear elasticity of the SR gels originate from a novel function of the slidable cross-links that can maximize the arrangement entropy of cross-linked and non-cross-linked cyclic molecules in the deformed networks.

Nonannual tree rings in a climate-sensitive Prioria copaifera chronology in the Atrato River, Colombia.

Science.gov (United States)

Herrera-Ramirez, David; Andreu-Hayles, Laia; Del Valle, Jorge I; Santos, Guaciara M; Gonzalez, Paula L M

2017-08-01

In temperate climates, tree growth dormancy usually ensures the annual nature of tree rings, but in tropical environments, determination of annual periodicity can be more complex. The purposes of the work are as follows: (1) to generate a reliable tree-ring width chronology for Prioria copaifera Griseb. (Leguminoceae), a tropical tree species dwelling in the Atrato River floodplains, Colombia; (2) to assess the climate signal recorded by the tree-ring records; and (3) to validate the annual periodicity of the tree rings using independent methods. We used standard dendrochronological procedures to generate the P. copaifera tree-ring chronology. We used Pearson correlations to evaluate the relationship of the chronology with the meteorological records, climate regional indices, and gridded precipitation/sea surface temperature products. We also evaluated 24 high-precision 14 C measurements spread over a range of preselected tree rings, with assigned calendar years by dendrochronological techniques, before and after the bomb spike in order to validate the annual nature of the tree rings. The tree-ring width chronology was statistically reliable, and it correlated significantly with local records of annual and October-December (OND) streamflow and precipitation across the upper river watershed (positive), and OND temperature (negative). It was also significantly related to the Oceanic Niño Index, Pacific Decadal Oscillation, and the Southern Oscillation Index, as well as sea surface temperatures over the Caribbean and the Pacific region. However, 14 C high-precision measurements over the tree rings demonstrated offsets of up to 40 years that indicate that P. copaifera can produce more than one ring in certain years. Results derived from the strongest climate-growth relationship during the most recent years of the record suggest that the climatic signal reported may be due to the presence of annual rings in some of those trees in recent years. Our study alerts about

On Semiprime Noetherian PI-Rings

OpenAIRE

Chiba, Katsuo

2000-01-01

Let R be a semiprime Noetherian PI-ring and Q(R) the semisimple Artinian ring of fractions of R. We shall prove the following conditions are equivalent: (1) the Krull dimention of R is at most one, (2) Any ring between R and Q(R) is again right Noetherian, (3) Let a, b be central regular elements of Q(R). Then the subring R + aR[b] of Q(R) is right Noetherian.

Development of stress analyzer using whole back reflection ring

International Nuclear Information System (INIS)

Shitaba, Yuichi; Ishikawa, Tetsuro; Ohya, Shin-ichi; Akita, Koichi

2006-01-01

The X-ray stress measurement based on sin 2 ψ method has been widely adopted. This technique is not entirely efficient, because it is necessary to measure each diffraction profile one after other at five and more incident X-ray angles. On the other hand, stress measurement based on cosα method was proposed using X-ray film as detector. In this method, the stresses are determined from Debye-ring obtained at a single X-ray incident angle with high efficiency. However, it has the problem in this accuracy on stress determination. In this study, a new stress analyzer with sixteen position sensitive proportional counters (PSPC) radially arranged for incidence X-ray was developed. We examined to determine the plane stress components by multi-regression analysis using sixteen diffraction angles on a Debye-ring. As a result, stress components of σ x and τ xy were measured with sufficient accuracy. However, a stress of σ y had large dispersion, because of low strain sensitivity in the y direction. Moreover, it was clarified that σ y had pseud-multicollinearity on multi-regression analysis. The accuracy of σ y value itself could not be improved, though an analysis to eliminate an effect of pseud-multicollinearity was carried out. In this paper, we proposed the new method to determine the components using two Debye rings obtained by X-ray incidences in both x and y directions. We tried to measure the residual stress components in the butt welded joint using the method. As a result, it was confirmed that the stresses, σ x and σ y , were obtained in the sufficient accuracy, and that the shear stress, τ xy , was arising near the bond in the welds. (author)

On zero divisor graph of unique product monoid rings over Noetherian reversible ring

Directory of Open Access Journals (Sweden)

Ebrahim Hashemi

2016-02-01

Full Text Available Let $R$ be an associative ring with identity and $Z^*(R$ be its set of non-zero zero divisors.  The zero-divisor graph of $R$, denoted by $Gamma(R$, is the graph whose vertices are the non-zero  zero-divisors of  $R$, and two distinct vertices $r$ and $s$ are adjacent if and only if $rs=0$ or $sr=0$.  In this paper, we bring some results about undirected zero-divisor graph of a monoid ring over reversible right (or left Noetherian ring $R$. We essentially classify the diameter-structure of this graph and show that $0leq mbox{diam}(Gamma(Rleq mbox{diam}(Gamma(R[M]leq 3$. Moreover, we give a characterization for the possible diam$(Gamma(R$ and diam$(Gamma(R[M]$, when $R$ is a reversible Noetherian ring and $M$ is a u.p.-monoid. Also, we study relations between the girth of $Gamma(R$ and that of $Gamma(R[M]$.

A study of channeling patterns from strained Si1-xGex/Si bilayers close to (011) axes

NARCIS (Netherlands)

Breese, MBH; Smulders, PJM

This paper characterises the angular intensity distribution of MeV protons transmitted through strained Si1-xGex/Si bilayers close to the axis. The ring-like intensity distribution produced by the front layer axis when it is aligned close to the beam direction is projected either towards or away

Persistent organic pollutants in ringed seals from the Russian Arctic.

Science.gov (United States)

Savinov, Vladimir; Muir, Derek C G; Svetochev, Vladislav; Svetocheva, Olga; Belikov, Stanislav; Boltunov, Andrey; Alekseeva, Ludmila; Reiersen, Lars-Otto; Savinova, Tatiana

2011-06-15

Organochlorine compounds total DDT (ΣDDT), total HCH isomers (ΣHCH), toxaphenes (sum of Parlar 26, 50, 62), mirex, endrin, methoxychlor, total chlorinated benzenes (ΣCBz), total chlordane compounds (ΣCHL), polychlorinated biphenyls (total of 56 congeners; ΣPCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (sum of 7 tri- to hepta congeners; ΣPBDEs) were analysed in the blubber of adult ringed seals from the four areas of the Russian Arctic (White Sea, Barents Sea, Kara Sea and Chukchi Sea) collected in 2001-2005. Ringed seals from the south-western part of the Kara Sea (Dikson Island - Yenisei estuary) were the most contaminated with ΣDDTs, ΣPCBs, ΣCHL, and mirex as compared with those found in the other three areas of Russian Arctic, while the highest mean concentrations of ΣHCHs and PCDD/Fs were found in the blubber of ringed seals from the Chukchi Sea and the White Sea, respectively. Among all organochlorine compounds measured in ringed seals from the European part of the Russian Arctic, concentrations of ΣDDT and ΣPCBs only were higher as compared with the other Arctic regions. Levels of all other organochlorine compounds were similar or lower than in seals from Svalbard, Alaska, the Canadian Arctic and Greenland. ΣPBDEs were found in all ringed seal samples analysed. There were no significant differences between ΣPBDE concentrations found in the blubber of ringed seals from the three studied areas of the European part of the Russian Arctic, while PBDE contamination level in ringed seals from the Chukchi Sea was 30-50 times lower. ΣPBDE levels in the blubber of seals from the European part of the Russian Arctic are slightly higher than in ringed seals from the Canadian Arctic, Alaska, and western Greenland but lower compared to ringed seals from Svalbard and eastern Greenland. Copyright © 2011 Elsevier B.V. All rights reserved.

Imidazolopiperazines (IPZ) kill both rings and dormant rings in wild type and K13 artemisinin resistant Plasmodium falciparum in vitro.

Science.gov (United States)

Dembele, Laurent; Gupta, Devendra Kumar; Lim, Michelle Yi-Xiu; Ang, Xiaoman; Selva, Jeremy J; Chotivanich, Kesinee; Nguon, Chea; Dondorp, Arjen M; Bonamy, Ghislain M C; Diagana, Thierry T; Bifani, Pablo

2018-03-12

Artemisinin (ART) resistance has spread through Southeast Asia, posing serious threat to the control and elimination of malaria. ART resistance has been associated with mutations in the Plasmodium falciparum kelch-13 ( Pfk13 ) propeller domain. Phenotypically, ART resistance is defined as delayed parasite clearance in patients' due to the reduced susceptibility of early ring-stage parasites to the active metabolite of ART dihydroartemisinin (DHA). Early rings can enter a state of quiescence upon DHA exposure and resume growth in its absence. These quiescent rings are referred to as dormant rings or DHA-pretreated rings (called here dormant rings). The imidazolopiperazine (IPZ) is a novel class of antimalarial drugs, which has demonstrated efficacy in early clinical trials. Here, we characterized the stage of action of IPZ GNF179 and evaluated its activity against rings and dormant rings in wild type and ART resistant parasites. Unlike DHA, GNF179 does not induce dormancy. We show that GNF179 is more rapidly cidal against schizonts than ring and trophozoite stages. However, with 12 hours exposure, the compound effectively kills rings and dormant rings of both susceptible and ART resistant parasites within 72 hours. We further demonstrate that in combination with ART, GNF179 effectively prevent recrudescence of dormant rings including those bearing pfk13 propeller mutations. Copyright © 2018 Dembele et al.

Persistent Corneal Decompensation due to Anterior Dislocation of Soemmering Ring Cataract

Directory of Open Access Journals (Sweden)

Travis Peck

2017-01-01

Full Text Available Purpose. We present a case of a patient with Soemmering ring after cataract surgery and a potential complication that can arise as a result of its presence. Observations. A patient with history of ruptured globe status after repair and lensectomy, complicated by aphakic secondary open angle glaucoma, was referred for management of second injury to the same eye. This injury resulted in Soemmering ring dislocation into the anterior chamber. The cortical material caused a significant increase in intraocular pressure and corneal decompensation. Surgical removal of the Soemmering ring and Ahmed glaucoma tube implant was performed with control of intraocular pressures; however corneal edema could not be reversed. Conclusions and Importance. This case report illustrates the serious consequences that can be caused by Soemmering rings without early surgical intervention. Care must be taken to completely remove cortical material during cataract surgery to prevent their formation.

Complete snake and rotator schemes for spin polarization in proton rings and large electron rings

International Nuclear Information System (INIS)

Steffen, K.

1983-11-01

In order to maintain spin polarization in proton rings and large electron rings, some generalized Siberian Snake scheme may be required to make the spin tune almost independent of energy and thus avoid depolarizing resonances. The practical problem of finding such schemes that, at reasonable technical effort, can be made to work over large energy ranges has been addressed before and is here revisited in a broadened view and with added new suggestions. As a result, possibly optimum schemes for electron rings (LEP) and proton rings are described. In the proposed LEP scheme, spin rotation is devised such that, at the interaction points, the spin direction is longitudinal as required for experiments. (orig.)

Antibacterial and Herbicidal Activity of Ring-Substituted 2-Hydroxynaphthalene-1-carboxanilides

Directory of Open Access Journals (Sweden)

Katarina Kralova

2013-08-01

Full Text Available In this study, a series of twenty-two ring-substituted 2-hydroxynaphthalene-1‑carboxanilides were prepared and characterized. Primary in vitro screening of the synthesized compounds was performed against Staphylococcus aureus, three methicillin-resistant S. aureus strains, Mycobacterium marinum, M. kasasii, M. smegmatis. and M. avium paratuberculosis. The compounds were also tested for their activity related to inhibition of photosynthetic electron transport (PET in spinach (Spinacia oleracea L. chloroplasts. 2-Hydroxy-N-phenylnaphthalene-1-carboxanilide and 2-hydroxy-N-(3-trifluoromethylphenylnaphthalene-1-carboxamide (IC50 = 29 µmol/L were the most active PET inhibitors. Some of tested compounds showed the antibacterial and antimycobacterial activity against the tested strains comparable or higher than the standards ampicillin or isoniazid. Thus, for example, 2-hydroxy-N-(3-nitrophenylnaphthalene-1-carboxamide showed MIC = 26.0 µmol/L against methicillin-resistant S. aureus and MIC = 51.9 µmol/L against M. marinum, or 2-hydroxy-N-phenylnaphthalene-1-carboxamide demonstrated MIC = 15.2 µmol/L against M. kansasii. The structure-activity relationships for all compounds are discussed.

Koffka's Ring Effect Depends on Thickness, Not Continuity

OpenAIRE

Abigail E. Huang; Alice J. Hon; Eric L. Altschuler

2007-01-01

More than 70 years ago Gestalt psychologist Kurt Koffka described a fascinating effect1,2: When a contiguous grey ring is placed on a background half of one shade of grey (different from the ring) and half of another shade of grey, the ring appears to be a homogenous. However, if the ring is slightly divided, now the two halves of the ring appear different shades of grey with the half of the ring on the darker background appearing lighter than the half of the ring on the darker background. Th...

Almost ring theory

CERN Document Server

2003-01-01

This book develops thorough and complete foundations for the method of almost etale extensions, which is at the basis of Faltings' approach to p-adic Hodge theory. The central notion is that of an "almost ring". Almost rings are the commutative unitary monoids in a tensor category obtained as a quotient V-Mod/S of the category V-Mod of modules over a fixed ring V; the subcategory S consists of all modules annihilated by a fixed ideal m of V, satisfying certain natural conditions. The reader is assumed to be familiar with general categorical notions, some basic commutative algebra and some advanced homological algebra (derived categories, simplicial methods). Apart from these general prerequisites, the text is as self-contained as possible. One novel feature of the book - compared with Faltings' earlier treatment - is the systematic exploitation of the cotangent complex, especially for the study of deformations of almost algebras.

IAG ring test animal proteins 2014

NARCIS (Netherlands)

Raamsdonk, van L.W.D.; Pinckaers, V.G.Z.; Scholtens-Toma, I.M.J.; Prins, T.W.; Voet, van der H.; Vliege, J.J.M.

2014-01-01

A ring test was organized for the detection of animal proteins in animal feed by microscopy in the framework of the annual ring tests of the IAG – International Association for Feeding stuff Analysis, Section Feeding stuff Microscopy. The aim of the ring study was to provide the participants

IAG ring test animal proteins 2015

NARCIS (Netherlands)

Raamsdonk, van L.W.D.; Rhee, van de N.E.; Scholtens-Toma, I.M.J.; Prins, T.W.; Vliege, J.J.M.; Pinckaers, V.G.Z.

2015-01-01

A ring test was organized for the detection of animal proteins in animal feed by microscopy in the framework of the annual ring tests of the IAG - International Association for Feeding stuff Analysis, Section Feeding stuff Microscopy. The organizer of the ring test was RIKILT - Wageningen UR, The

IAG ring test animal proteins 2013

NARCIS (Netherlands)

Raamsdonk, van L.W.D.; Pinckaers, V.G.Z.; Scholtens-Toma, I.M.J.; Prins, T.W.; Vliege, J.J.M.

2013-01-01

A ring test was organized for the detection of animal proteins in animal feed by microscopy in the framework of the annual ring tests of the IAG - International Association for Feeding stuff Analysis, Section Feeding stuff Microscopy. The organizer of the the ring study was to provide the

Impact of imitation processes on the effectiveness of ring vaccination.

Science.gov (United States)

Wells, Chad R; Tchuenche, Jean M; Meyers, Lauren Ancel; Galvani, Alison P; Bauch, Chris T

2011-11-01

Ring vaccination can be a highly effective control strategy for an emerging disease or in the final phase of disease eradication, as witnessed in the eradication of smallpox. However, the impact of behavioural dynamics on the effectiveness of ring vaccination has not been explored in mathematical models. Here, we analyze a series of stochastic models of voluntary ring vaccination. Contacts of an index case base vaccinating decisions on their own individual payoffs to vaccinate or not vaccinate, and they can also imitate the behaviour of other contacts of the index case. We find that including imitation changes the probability of containment through ring vaccination considerably. Imitation can cause a strong majority of contacts to choose vaccination in some cases, or to choose non-vaccination in other cases-even when the equivalent solution under perfectly rational (non-imitative) behaviour yields mixed choices. Moreover, imitation processes can result in very different outcomes in different stochastic realizations sampled from the same parameter distributions, by magnifying moderate tendencies toward one behaviour or the other: in some realizations, imitation causes a strong majority of contacts not to vaccinate, while in others, imitation promotes vaccination and reduces the number of secondary infections. Hence, the effectiveness of ring vaccination can depend significantly and unpredictably on imitation processes. Therefore, our results suggest that risk communication efforts should be initiated early in an outbreak when ring vaccination is to be applied, especially among subpopulations that are heavily influenced by peer opinions.

Biomarkers and biometric measures of adherence to use of ARV-based vaginal rings.

Science.gov (United States)

Stalter, Randy M; Moench, Thomas R; MacQueen, Kathleen M; Tolley, Elizabeth E; Owen, Derek H

2016-01-01

Poor adherence to product use has been observed in recent trials of antiretroviral (ARV)-based oral and vaginal gel HIV prevention products, resulting in an inability to determine product efficacy. The delivery of microbicides through vaginal rings is widely perceived as a way to achieve better adherence but vaginal rings do not eliminate the adherence challenges exhibited in clinical trials. Improved objective measures of adherence are needed as new ARV-based vaginal ring products enter the clinical trial stage. To identify technologies that have potential future application for vaginal ring adherence measurement, a comprehensive literature search was conducted that covered a number of biomedical and public health databases, including PubMed, Embase, POPLINE and the Web of Science. Published patents and patent applications were also searched. Technical experts were also consulted to gather more information and help evaluate identified technologies. Approaches were evaluated as to feasibility of development and clinical trial implementation, cost and technical strength. Numerous approaches were identified through our landscape analysis and classified as either point measures or cumulative measures of vaginal ring adherence. Point measurements are those that give a measure of adherence at a particular point in time. Cumulative measures attempt to measure ring adherence over a period of time. Approaches that require modifications to an existing ring product are at a significant disadvantage, as this will likely introduce additional regulatory barriers to the development process and increase manufacturing costs. From the point of view of clinical trial implementation, desirable attributes would be high acceptance by trial participants, and little or no additional time or training requirements on the part of participants or clinic staff. We have identified four promising approaches as being high priority for further development based on the following measurements

Dipole Magnets for the LHeC Ring-Ring Option

CERN Document Server

Tommasini, D; Chritin, R

2012-01-01

The Ring-Ring option of a Large Hadron electron Collider (LHeC) requires 3080 bending magnets, 5.35-meter-long each providing a magnetic field ranging from 0.0127 T at 10 GeV to 0.0763 T at 60 GeV. Main issues in the design of these magnets are the very low injection field, constituting a challenge in achieving a satisfactory field reproducibility from cycle to cycle, and the required compactness to fit in the existing LHC tunnel. This paper describes and discusses a design meeting these requirements, together with its experimental validation by the manufacture and measurement of a 400-mm-long magnet model.

The multi-bend achromat storage rings

Energy Technology Data Exchange (ETDEWEB)

Eriksson, Mikael [MAX IV Laboratory Ole Römers v. 1 22100 Lund Sweden (Sweden)

2016-07-27

Not very long ago, the 3{sup rd} generation storage ring technology was judged as mature. Most of the 3{sup rd} generation storage rings used the Double-Bend Achromat (DBA) or Triple-Bend Achromat (TBA) concepts. It was however a well-known fact that increasing the number of magnet cells in the rings is a powerful way of decreasing the electron beam emittance and thus the source brilliance, but at the penalty of increasing the size and cost of the rings. Preserving the Dynamic Aperture (DA) in the rings became also an issue when increasing the number of magnet cells. The Multi-Bend Achromat (MBA) concept, including a miniaturization of the ring elements, has now drastically changed the picture. The MBA rings, now in construction or being planned, offer orders of magnitudes higher brilliance than rings of conventional designs. Several light sources around the world are now implementing or planning to implement this MBA concept. This article touches on the science drivers for higher brilliance. We will then describe the MBA concept with its advantages as well as its challenges. A short survey of the MBA activity around the world will also be presented. The author apologies for focusing on the MAX IV project regarding technical solutions. This is motivated by that MAX IV is the facility he knows best and it might be regarded as a fore-runner for the MBA concept.

The multi-bend achromat storage rings

International Nuclear Information System (INIS)

Eriksson, Mikael

2016-01-01

Not very long ago, the 3"r"d generation storage ring technology was judged as mature. Most of the 3"r"d generation storage rings used the Double-Bend Achromat (DBA) or Triple-Bend Achromat (TBA) concepts. It was however a well-known fact that increasing the number of magnet cells in the rings is a powerful way of decreasing the electron beam emittance and thus the source brilliance, but at the penalty of increasing the size and cost of the rings. Preserving the Dynamic Aperture (DA) in the rings became also an issue when increasing the number of magnet cells. The Multi-Bend Achromat (MBA) concept, including a miniaturization of the ring elements, has now drastically changed the picture. The MBA rings, now in construction or being planned, offer orders of magnitudes higher brilliance than rings of conventional designs. Several light sources around the world are now implementing or planning to implement this MBA concept. This article touches on the science drivers for higher brilliance. We will then describe the MBA concept with its advantages as well as its challenges. A short survey of the MBA activity around the world will also be presented. The author apologies for focusing on the MAX IV project regarding technical solutions. This is motivated by that MAX IV is the facility he knows best and it might be regarded as a fore-runner for the MBA concept.

Ring wormholes via duality rotations

Directory of Open Access Journals (Sweden)

Gary W. Gibbons

2016-09-01

Full Text Available We apply duality rotations and complex transformations to the Schwarzschild metric to obtain wormhole geometries with two asymptotically flat regions connected by a throat. In the simplest case these are the well-known wormholes supported by phantom scalar field. Further duality rotations remove the scalar field to yield less well known vacuum metrics of the oblate Zipoy–Voorhees–Weyl class, which describe ring wormholes. The ring encircles the wormhole throat and can have any radius, whereas its tension is always negative and should be less than −c4/4G. If the tension reaches the maximal value, the geometry becomes exactly flat, but the topology remains non-trivial and corresponds to two copies of Minkowski space glued together along the disk encircled by the ring. The geodesics are straight lines, and those which traverse the ring get to the other universe. The ring therefore literally produces a hole in space. Such wormholes could perhaps be created by negative energies concentrated in toroidal volumes, for example by vacuum fluctuations.

Differential Geometry Applied to Rings and Möbius Nanostructures

DEFF Research Database (Denmark)

Lassen, Benny; Willatzen, Morten; Gravesen, Jens

2014-01-01

Nanostructure shape effects have become a topic of increasing interest due to advancements in fabrication technology. In order to pursue novel physics and better devices by tailoring the shape and size of nanostructures, effective analytical and computational tools are indispensable. In this chap......Nanostructure shape effects have become a topic of increasing interest due to advancements in fabrication technology. In order to pursue novel physics and better devices by tailoring the shape and size of nanostructures, effective analytical and computational tools are indispensable....... In this chapter, we present analytical and computational differential geometry methods to examine particle quantum eigenstates and eigenenergies in curved and strained nanostructures. Example studies are carried out for a set of ring structures with different radii and it is shown that eigenstate and eigenenergy...

Evidence for Quantisation in Planetary Ring Systems

OpenAIRE

WAYTE, RICHARD

2017-01-01

Absolute radial positions of the main features in Saturn's ring system have been calculated by adapting the quantum theory of atomic spectra. Fine rings superimposed upon broad rings are found to be covered by a harmonic series of the form N α A(r)1/2, where N and A are integers. Fourier analysis of the ring system shows that the spectral amplitude fits a response profile which is characteristic of a resonant system. Rings of Jupiter, Uranus and Neptune also obey the same rules. Involvement o...

Ring species as demonstrations of the continuum of species formation

DEFF Research Database (Denmark)

Pereira, Ricardo José Do Nascimento; Wake, David B.

2015-01-01

In the mid-20th century, Ernst Mayr (1942) and Theodosius Dobzhansky (1958) championed the significance of 'circular overlaps' or 'ring species' as the perfect demonstration of the gradual nature of species formation. As an ancestral species expands its range, wrapping around a geographic barrier......? What conditions favour their formation? Modelling studies have attempted to address these knowledge gaps by estimating the biological parameters that result in stable ring species (Martins et al. 2013), and determining the necessary topographic parameters of the barriers encircled (Monahan et al. 2012......). However, any generalization is undermined by a major limitation: only a handful of ring species are known to exist in nature. In addition, many of them have been broken into multiple species presumed to be evolving independently, usually obscuring the evolutionary dynamics that generate diversity. A paper...

Multiplication modules over non-commutative rings

International Nuclear Information System (INIS)

Tuganbaev, A A

2003-01-01

It is proved that each submodule of a multiplication module over a regular ring is a multiplicative module. If A is a ring with commutative multiplication of right ideals, then each projective right ideal is a multiplicative module, and a finitely generated A-module M is a multiplicative module if and only if all its localizations with respect to maximal right ideals of A are cyclic modules over the corresponding localizations of A. In addition, several known results on multiplication modules over commutative rings are extended to modules over not necessarily commutative rings

Status of the SLC damping rings

International Nuclear Information System (INIS)

Hutton, A.M.; Davies-White, W.A.; Delahaye, J.P.

1985-06-01

Electron beams of full design energy 1.21 GeV and nearly full design intensity 4 x 10 10 particles/pulse (design 5 x 10 10 ) have been extracted from the Stanford Linac and successfully stored in the electron damping ring. Beams of less intensity have been extracted from the ring and reinjected into the Linac. The present intensity limits are not thought to be fundamental. The operating experience with the electron ring and the status of the construction of the positron ring will be discussed. 11 refs., 1 fig., 2 tabs

Ring-substituted 4-Hydroxy-1H-quinolin-2-ones: Preparation and Biological Activity

Directory of Open Access Journals (Sweden)

Jiri Dohnal

2009-03-01

Full Text Available In the study, a series of twelve ring-substituted 4-hydroxy-1H-quinolin-2-one derivatives were prepared. The procedures for synthesis of the compounds are presented. The compounds were analyzed using RP-HPLC to determine lipophilicity and tested for their photosynthesis-inhibiting activity using spinach (Spinacia oleracea L. chloroplasts. All the synthesized compounds were also evaluated for antifungal activity using in vitro screening with eight fungal strains. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds are discussed, as well as their structure-activity relationships (SAR.

The role of substorms in the formation of the ring current

International Nuclear Information System (INIS)

Rostoker, G.

1996-01-01

It has long been recognized that the formation of the terrestrial ring current is accompanied by strong substorm expansive phase activity in the auroral oval. While large amplitude substorm activity seems to be a prerequisite for ring current formation to take place, it has long been puzzling as to why some large amplitude substorm activity in the auroral oval is not associated with significant ring current development. In this paper I shall outline the basis for the renovated boundary layer dynamics model of magnetospheric substorms showing how the onset of the substorm expansive phase can be associated with a sudden decrease in shielding space charge in the region of the near-Earth plasma sheet threaded by Region 2 field-aligned currents. I shall suggest that an episode of sufficiently large southward IMF lasting over a sufficiently lengthy period of time can lead to a sequence of substorm expansive phases, each one being initiated closer to the Earth than the previous one. Each expansive phase is attributed to a sudden decrease in radially localized cross-tail current (viz. a decrease in shielding space charge) and with each onset the inner edge of the plasma sheet moves inward. The inductive electric field associated with each crosstail current decrease is responsible for the acceleration of already energetic particles to energies of significance for ring current formation. Only when the inner edge of the crosstail current is sufficiently close to the Earth do the acceleration processes associated with substorm onset produce a long lived ring current. copyright 1996 American Institute of Physics

Characterization of heterocyclic rings through quantum chemical topology.

Science.gov (United States)

Griffiths, Mark Z; Popelier, Paul L A

2013-07-22

Five-membered rings are found in a myriad of molecules important in a wide range of areas such as catalysis, nutrition, and drug and agrochemical design. Systematic insight into their largely unexplored chemical space benefits from first principle calculations presented here. This study comprehensively investigates a grand total of 764 different rings, all geometry optimized at the B3LYP/6-311+G(2d,p) level, from the perspective of Quantum Chemical Topology (QCT). For the first time, a 3D space of local topological properties was introduced, in order to characterize rings compactly. This space is called RCP space, after the so-called ring critical point. This space is analogous to BCP space, named after the bond critical point, which compactly and successfully characterizes a chemical bond. The relative positions of the rings in RCP space are determined by the nature of the ring scaffold, such as the heteroatoms within the ring or the number of π-bonds. The summed atomic QCT charges of the five ring atoms revealed five features (number and type of heteroatom, number of π-bonds, substituent and substitution site) that dictate a ring's net charge. Each feature independently contributes toward a ring's net charge. Each substituent has its own distinct and systematic effect on the ring's net charge, irrespective of the ring scaffold. Therefore, this work proves the possibility of designing a ring with specific properties by fine-tuning it through manipulation of these five features.

Dynamics of satellites, asteroids, and rings

International Nuclear Information System (INIS)

Dermott, S.F.

1987-01-01

Work is reported on: (1) the shapes and the internal structures of satellites; (2) the tidal heating of Miranda; (3) the dynamics of arc-like rings; and (4) the structure of the zodiacal cloud that was revealed by the Infrared Astronomy Satellite. Significant progress was made in determining the shape and internal structure of Mimas and in understanding the dynamical evolution of Miranda's orbit

Single photon emission and quantum ring-cavity coupling in InAs/GaAs quantum rings

International Nuclear Information System (INIS)

Gallardo, E; Nowak, A K; Sanvitto, D; Meulen, H P van der; Calleja, J M; MartInez, L J; Prieto, I; Alija, A R; Granados, D; Taboada, A G; GarcIa, J M; Postigo, P A; Sarkar, D

2010-01-01

Different InAs/GaAs quantum rings embedded in a photonic crystal microcavity are studied by quantum correlation measurements. Single photon emission, with g (2) (0) values around 0.3, is demonstrated for a quantum ring not coupled to the microcavity. Characteristic rise-times are found to be longer for excitons than for biexcitons, resulting in the time asymmetry of the exciton-biexciton cross-correlation. No antibunching is observed in another quantum ring weakly coupled to the microcavity.

Synthetic Applications of Flexible SNO-OCT Strained Alkynes and Their Use in Postpolymerization Modifications.

Science.gov (United States)

Burke, Eileen G; Schomaker, Jennifer M

2017-09-01

SNO-OCTs are eight-membered heterocyclic alkynes that have fast rates of reactivity with 1,3-dipoles. In contrast to many other reported cycloalkynes, SNO-OCTs contain multiple sites for derivatization, display stability under a variety of common reaction conditions, and offer the opportunity for strain-induced ring-opening following the initial reaction of the alkyne moiety. In this paper, we describe how the unique features of SNO-OCTs can be employed to modify an oxime-bearing styrene copolymer and introduce an array of polar functionalities into the polymer. This can be achieved through both the addition of SNO-OCT to the polymer, as well as in the subsequent opening of the sulfamate ring once it has been installed in the polymer.

Powder metallurgy ferrous synchronizer ring with brass-based friction layer; Tetsu-do niso shoketsu synchronize ring no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Okajima, H; Yoshikawa, K; Miyajima, K; Sugiyama, M [Toyota Motor Corp., Aichi (Japan); Nakamura, M; Ito, M [Japan Powder Metallurgy Co. Ltd., Tokyo (Japan)

1997-10-01

Synchronizer rings for manual transmissions are generally made of brass or molybdenum coated brass. Powder metallurgy (PM) synchronizer ring was developed for the purpose of high performance and cost reduction. This synchronizer ring consists of the high strength PM ferrous ring that needs neither special densification nor heat treatment, and it has the brass-based friction layer. New joining technique was required because of that shape and two different materials. Powder of copper-phosphorus alloy are admixed with the friction material. While sintering, that melt and migrate to the interface. Then the friction layer and the ferrous ring are joined tightly. 7 refs., 9 figs., 6 tabs.

The improvement of the superconducting Y-Ba-Cu-O magnet characteristics through shape recovery strain of Fe-Mn-Si alloys

International Nuclear Information System (INIS)

Shimpo, Y.; Seki, H.; Wongsatanawarid, A.; Taniguchi, S.; Maruyama, T.; Kurita, T.; Murakami, M.

2010-01-01

Since bulk Y-Ba-Cu-O superconductors are brittle ceramics, reinforcement of mechanical properties is important for practical applications. It has been reported that bulk Y-Ba-Cu-O can be reinforced with Al or Fe based alloy ring, in that compression force acts on bulk Y-Ba-Cu-O due to a difference in thermal expansion coefficients. However, the shrinkage of the metal ring was not so large, and therefore careful adjustment of the circumference of the bulk and the metal rings was necessary. In this study, we employed Fe-Mn-Si shape memory alloy rings to reinforce bulk Y-Ba-Cu-O. The advantage of the shape memory alloy is that the shrinkage can take place on heating, and furthermore, the alloy shrinks and compresses the bulk body on cooling. Bulk Y-Ba-Cu-O superconductor 22.8 mm in diameter was inserted in a Fe-Mn-Si ring 23.0 mm in inner diameter at room temperature. Beforehand, the Fe-Mn-Si ring was expanded by 12% strain at room temperature. Then the composite was heated to 673 K. At room temperature, the Fe-Mn-Si ring firmly gripped the bulk superconductor. We then measured trapped fields before and after the ring reinforcement, and found that the trapped field was improved through the treatment.

Analytical solutions for the invariant spin field for model storage rings

International Nuclear Information System (INIS)

Mane, S.R.

2002-01-01

We present nonperturbative analytical expressions for the invariant spin field for several storage ring models. In particular, we solve the important models of a ring with one Snake and a single resonance driving term, and a ring with two Snakes and a single resonance driving term. We also treat several other models, all of which contain Siberian Snakes. Our solutions contain some novel features, e.g. in some cases the polarization does not point along the direction of the closed-orbit spin quantization axis. We also include vertical resonance driving terms, and consider the contributions of sextupoles and higher order multipoles to the resonance driving terms, and argue that these can play a significant role in some circumstances. We offer some brief remarks on the so-called Snake resonances. We relate our results to observations of higher-order depolarizing spin resonances for polarized proton beams in a real ring, and offer some suggestions as to how our ideas might be verified

Vortex Ring Dynamics in Radially Confined Domains

Science.gov (United States)

Stewart, Kelley; Niebel, Casandra; Jung, Sunghwan; Vlachos, Pavlos

2010-11-01

Vortex ring dynamics have been studied extensively in semi-infinite quiescent volumes. However, very little is known about vortex-ring formation in wall-bounded domains where vortex wall interaction will affect both the vortex ring pinch-off and propagation velocity. This study addresses this limitation and studies vortex formation in radially confined domains to analyze the affect of vortex-ring wall interaction on the formation and propagation of the vortex ring. Vortex rings were produced using a pneumatically driven piston cylinder arrangement and were ejected into a long cylindrical tube which defined the confined downstream domain. A range of confinement domains were studied with varying confinement diameters Velocity field measurements were performed using planar Time Resolved Digital Particle Image Velocimetry (TRDPIV) and were processed using an in-house developed cross-correlation PIV algorithm. The experimental analysis was used to facilitate the development of a theoretical model to predict the variations in vortex ring circulation over time within confined domains.

The Conversion of Wiswesser Line Notations to Ring Codes. I. The Conversion of Ring Systems

Science.gov (United States)

Granito, Charles E.; And Others

1972-01-01

The computerized conversion of Wiswesser Line Notations to Ring Codes, using a two-part approach, and the set of computer programs generated for the conversion of ring systems are described. (9 references) (Author)

Interaction of a vortex ring and a bubble

Science.gov (United States)

Jha, Narsing K.; Govardhan, Raghuraman N.

2014-11-01

Micro-bubble injection in to boundary layers is one possible method for reducing frictional drag of ships. Although this has been studied for some time, the physical mechanisms responsible for drag reduction using microbubbles in turbulent boundary layers is not yet fully understood. Previous studies suggest that bubble-vortical structure interaction seems to be one of the important physical mechanisms for frictional drag reduction using microbubbles. In the present work, we study a simplification of this problem, namely, the interaction of a single vortical structure, in particular a vortex ring, with a single bubble for better understanding of the physics. The vortex ring is generated using a piston-cylinder arrangement and the bubble is generated by connecting a capillary to an air pump. The bubble dynamics is directly visualized using a high speed camera, while the vorticity modification is measured using time resolved PIV. The results show that significant deformations can occur of both the bubble and the vortex ring. Effect of different non-dimensional parameters on the interaction will be presented in the meeting.

Variation of Ring Width and Wood Density in Two Unmanaged Stands of the Mediterranean Oak Quercus faginea

Directory of Open Access Journals (Sweden)

Vicelina B. Sousa

2018-01-01

Full Text Available Ring width and wood density variation were studied from pith-to-bark and along the stem in two naturally regenerated stands of Quercus faginea Lam. in Portugal. Ring width was significantly different between sites, in both heartwood and sapwood rings, ranging from 1.83 mm to 2.52 mm and from 0.77 mm to 2.11 mm, respectively. Wood density was significantly different between sites only in the heartwood, i.e., 914 kg m−3 and 1037 kg m−3. Site effects were the main source of variation for ring width and wood density within the heartwood as well as for sapwood ring width, while the between-tree effects explained more the density variation within the sapwood. Wood density showed within-tree uniformity that was not affected by site. The stand characteristics such as basal area and tree age may override the environmental growth conditions. There was also a weak correlation between wood density and ring width components therefore suggesting the possibility of forestry management for both fast tree growth and high wood density.

The Saturnian rings

International Nuclear Information System (INIS)

Alfven, H.

1975-09-01

The structure of the Saturnian rings is traditionally believed to be due to resonances caused by Mimas (and possibly other satellites). It is shown that both theoretical and observational evidence rule out this interpretation. The increased observational accuracy on one hand and the increased understanding of the cosmogonic processes on the other makes it possible to explain the structure of the ring system as a product of condensation from a partially corotating plasma. In certain respects the agreement between theory and observations is about 1%. (Auth.)

Hubble again views Saturn's Rings Edge-on

Science.gov (United States)

1995-01-01

Saturn's magnificent ring system is seen tilted edge-on -- for the second time this year -- in this NASA Hubble Space Telescope picture taken on August 10, 1995, when the planet was 895 million miles (1,440 million kilometers) away. Hubble snapped the image as Earth sped back across Saturn's ring plane to the sunlit side of the rings. Last May 22, Earth dipped below the ring plane, giving observers a brief look at the backlit side of the rings. Ring-plane crossing events occur approximately every 15 years. Earthbound observers won't have as good a view until the year 2038. Several of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are from left to right, Enceladus, Tethys, Dione and Mimas. 'The Hubble data shows numerous faint satellites close to the bright rings, but it will take a couple of months to precisely identify them,' according to Steve Larson (University of Arizona). During the May ring plane crossing, Hubble detected two, and possibly four, new moons orbiting Saturn. These new observations also provide a better view of the faint E ring, 'to help determine the size of particles and whether they will pose a collision hazard to the Cassini spacecraft,' said Larson. The picture was taken with Hubble's Wide Field Planetary Camera 2 in wide field mode. This image is a composite view, where a long exposure of the faint rings has been combined with a shorter exposure of Saturn's disk to bring out more detail. When viewed edge-on, the rings are so dim they almost disappear because they are very thin -- probably less than a mile thick.The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Vaginal rings for delivery of HIV microbicides.

Science.gov (United States)

Malcolm, R Karl; Fetherston, Susan M; McCoy, Clare F; Boyd, Peter; Major, Ian

2012-01-01

Following the successful development of long-acting steroid-releasing vaginal ring devices for the treatment of menopausal symptoms and contraception, there is now considerable interest in applying similar devices to the controlled release of microbicides against HIV. In this review article, the vaginal ring concept is first considered within the wider context of the early advances in controlled-release technology, before describing the various types of ring device available today. The remainder of the article highlights the key developments in HIV microbicide-releasing vaginal rings, with a particular focus on the dapivirine ring that is presently in late-stage clinical testing.

Common pass decentered annular ring resonator

Energy Technology Data Exchange (ETDEWEB)

Holmes, D. A.; Waite, T. R.

1985-04-30

An optical resonator having an annular cylindrical gain region for use in a chemical laser or the like in which two ring-shaped mirrors having substantially conical reflecting surfaces are spaced apart along a common axis of revolution of the respective conical surfaces. A central conical mirror reflects incident light directed along said axis radially outwardly to the reflecting surface of a first one of the ring-shaped mirrors. The radial light rays are reflected by the first ring mirror to the second ring mirror within an annular cylindrical volume concentric with said common axis and forming a gain region. Light rays impinging on the second ring mirror are reflected to diametrically opposite points on the same conical mirror surfaces and back to the first ring mirror through the same annular cylindrical volume. The return rays are then reflected by the conical mirror surface of the first ring mirror back to the central conical mirror. The mirror surfaces are angled such that the return rays are reflected back along the common axis by the central mirror in a concentric annular cylindrical volume. A scraper mirror having a central opening centered on said axis and an offset opening reflects all but the rays passing through the two openings in an output beam. The rays passing through the second opening are reflected back through the first opening to provide feedback.

Tritium concentrations in tree ring cellulose

International Nuclear Information System (INIS)

Kaji, Toshio; Momoshima, Noriyuki; Takashima, Yoshimasa.

1989-01-01

Measurements of tritium (tissue bound tritium; TBT) concentration in tree rings are presented and discussed. Such measurement is expected to provide a useful means of estimating the tritium level in the environment in the past. The concentration of tritium bound in the tissue (TBT) in a tree ring considered to reflect the environmental tritium level in the area at the time of the formation of the ring, while the concentration of tritium in the free water in the tissue represents the current environmental tritium level. First, tritium concentration in tree ring cellulose sampled from a cedar tree grown in a typical environment in Fukuoka Prefecture is compared with the tritium concentration in precipitation in Tokyo. Results show that the year-to-year variations in the tritium concentration in the tree rings agree well with those in precipitation. The maximum concentration, which occurred in 1963, is attibuted to atmospheric nuclear testing which was performed frequently during the 1961 - 1963 period. Measurement is also made of the tritium concentration in tree ring cellulose sampled from a pine tree grown near the Isotope Center of Kyushu University (Fukuoka). Results indicate that the background level is higher probably due to the release of tritium from the facilities around the pine tree. Thus, measurement of tritium in tree ring cellulose clearly shows the year-to-year variation in the tritium concentration in the atmosphere. (N.K.)

Inorganic glass ceramic slip rings

Science.gov (United States)

Glossbrenner, E. W.; Cole, S. R.

1972-01-01

Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

Influence of hydrides orientation on strain, damage and failure of hydrided zircaloy-4

International Nuclear Information System (INIS)

Racine, A.

2005-09-01

In pressurized water reactors of nuclear power plants, fuel pellets are contained in cladding tubes, made of Zirconium alloy, for instance Zircaloy-4. During their life in the primary water of the reactor (155 bars, 300 C), cladding tubes are oxidized and consequently hydrided. A part of the hydrogen given off precipitates as Zirconium hydrides in the bulk material and embrittles the material. This embrittlement depends on many parameters, among which hydrogen content and orientation of hydrides with respect to the applied stress. This investigation is devoted to the influence of the orientation of hydrides with respect to the applied stress on strain, damage and failure mechanisms. Macroscopic and SEM in-situ ring tensile tests are performed on cladding tube material (unirradiated cold worked stress-relieved Zircaloy-4) hydrided with about 200 and 500 wppm hydrogen, and with different main hydrides orientation: either parallel or perpendicular to the circumferential tensile direction. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. Neither the tensile stress-strain response nor the global and local strain modes are significantly affected by hydrogen content or hydride orientation, but the failure modes are strongly modified. Indeed, only 200 wppm radial hydrides embrittle Zy-4: sample fail in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases sample reach at least 750 MPa before necking and final failure, in ductile or brittle mode. To model this particular heterogeneous material behavior, a non-coupled damage approach which takes into account the anisotropic distribution of the hydrides is proposed. Its parameters are identified from the macroscopic strain field measurements and a

Translational velocity oscillations of piston generated vortex rings

Science.gov (United States)

Kumar, Manoj; Arakeri, J. H.; Shankar, P. N.

1995-11-01

Experimental results are presented that show that the translational velocities of piston generated vortex rings often undergo oscillations, similar to those recently discovered for drop generated rings. An attempt has been made to minimize uncertainties by utilizing both dye and hydrogen bubbles for visualization and carefully repeating measurements on the same ring and on different realizations under the same nominal piston conditions. The results unambiguously show that under most conditions, both for laminar and turbulent rings and for rings generated from pipes and orifices, the oscillations are present. The present results, together with the earlier results on drop generated rings, give support to the view that translational velocity oscillations are probably an inherent feature of translating vortex ring fields.

Retrospective evaluation of tritium fallout by tree-ring analysis

International Nuclear Information System (INIS)

Kozak, K.; Biro, T.; Golder, F.; Rank, D.; Rajner, V.; Staudner, F.

1993-01-01

Tritium analyses of tree-ring cellulose were made to test its suitability for retrospective evaluation of a local tritium fallout. Several spruce trees were taken from an Austrian alpine area where tritium contamination of May 1974 precipitation had been detected. Wood from the annual growth rings of 1973, 1974 and 1975 was separated and the cellulose extracted. After isotopic equilibration with dead water, cellulose was combusted to yield water, whose tritium concentration was measured by liquid scintillation counting. Rigorous statistical treatment proved the significance of the increased tritium concentration caused by the tritium anomaly, which occurred during the growing season. The long-term trends of local atmospheric tritium, including the 1974 peak, were also well reflected by analysis of a 24-year ring sequence from a single tree in the contaminated area. The tritium data gained by the given method can be used at present qualitatively and a better understanding of the possible sources of contamination is required in order that the quantitative criteria be satisfied. (Author)

Saturn's Ring: Pre-Cassini Status and Mission Goals

Science.gov (United States)

Cuzzi, Jeff N.; DeVincenzi, Donald L. (Technical Monitor)

1999-01-01

In November 1980, and again in August 1981, identical Voyager spacecraft flew through the Saturn system, changing forever the way we think about planetary rings. Although Saturn's rings had been the only known ring system for three centuries, a ring system around Uranus had been discovered by stellar occultations from Earth in 1977, and the nearly transparent ring of Jupiter was imaged by Voyager in 1979 (the presence of material there had been inferred from charged particle experiments on Pioneer 10 and 11 several years earlier). While Saturn had thus temporarily lost its uniqueness as having the only ring system, with Voyager it handily recaptured the role of having the most fascinating one. The Voyager breakthroughs included spiral density and bending waves such as cause galactic structure; ubiquitous fine-scale radial 'irregular' structure, with the appearance of record-grooves; regional and local variations in particle color; complex, azimuthally variable ring structure; empty gaps in the rings, some containing very regular, sharp-edged, elliptical rings and one containing both a small moonlet and incomplete arcs of dusty material; and shadowy 'spokes' that flicker across the main rings. One of the paradigm shifts of this period was the realization that many aspects of planetary rings, and even the ring systems themselves, could be 'recent' on geological timescales. These early results are reviewed and summarized in the Arizona Space Science series volumes 'Saturn'. (An excellent review of ring dynamics at a formative stage is by Goldreich and Tremaine.) From the mid 1980's to the time of this writing, progress has been steady, while at a less heady pace, and some of the novel ring properties revealed by Voyager 1 and 2 are beginning to be better understood. It is clearly impossible to cite, much less review, every advance over the last decade; however, below we summarize the main advances in understanding of Saturn's rings since the mid 1980's, in the context

Rings Related to Special Atoms | France-Jackson | Quaestiones ...

African Journals Online (AJOL)

Abstract unavailable at this time... Mathematics Subject Classification (1991): 16A21, 16A12 Keywords: ring, special atoms, atoms, *k-ring, prime ring, *-ring, Jacobson, artinia, essential extension, homomorphic image, ideals. Quaestiones Mathematicae 24(1) 2001, 105–109 ...

Functional characterization of 3-ketosteroid 9α-hydroxylases in Rhodococcus ruber strain chol-4.

Science.gov (United States)

Guevara, Govinda; Heras, Laura Fernández de Las; Perera, Julián; Llorens, Juana María Navarro

2017-09-01

The 3-Ketosteroid-9α-Hydroxylase, also known as KshAB [androsta-1,4-diene-3,17-dione, NADH:oxygen oxidoreductase (9α-hydroxylating); EC 1.14.13.142)], is a key enzyme in the general scheme of the bacterial steroid catabolism in combination with a 3-ketosteroid-Δ 1 -dehydrogenase activity (KstD), being both responsible of the steroid nucleus (rings A/B) breakage. KshAB initiates the opening of the steroid ring by the 9α-hydroxylation of the C9 carbon of 4-ene-3-oxosteroids (e.g. AD) or 1,4-diene-3-oxosteroids (e.g. ADD), transforming them into 9α-hydroxy-4-androsten-3,17-dione (9OHAD) or 9α-hydroxy-1,4-androstadiene-3,17-dione (9OHADD), respectively. The redundancy of these enzymes in the actinobacterial genomes results in a serious difficulty for metabolic engineering this catabolic pathway to obtain intermediates of industrial interest. In this work, we have identified three homologous kshA genes and one kshB gen in different genomic regions of R. ruber strain Chol-4. We present a set of data that helps to understand their specific roles in this strain, including: i) description of the KshAB enzymes ii) construction and characterization of ΔkshB and single, double and triple ΔkshA mutants in R. ruber iii) growth studies of the above strains on different substrates and iv) genetic complementation and biotransformation assays with those strains. Our results show that KshA2 isoform is needed for the degradation of steroid substrates with short side chain, while KshA3 works on those molecules with longer side chains. KshA1 is a more versatile enzyme related to the cholic acid catabolism, although it also collaborates with KshA2 or KshA3 activities in the catabolism of steroids. Accordingly to what it is described for other Rhodococcus strains, our results also suggest that the side chain degradation is KshAB-independent. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transcription and expression of Plasmodium falciparum histidine-rich proteins in different stages and strains: implications for rapid diagnostic tests.

Directory of Open Access Journals (Sweden)

Joanne Baker

Full Text Available BACKGROUND: Although rapid diagnostic tests (RDTs for Plasmodium falciparum infection that target histidine rich protein 2 (PfHRP2 are generally sensitive, their performance has been reported to be variable. One possible explanation for variable test performance is differences in expression level of PfHRP in different parasite isolates. METHODS: Total RNA and protein were extracted from synchronised cultures of 7 P. falciparum lines over 5 time points of the life cycle, and from synchronised ring stages of 10 falciparum lines. Using quantitative real-time polymerase chain reaction, Western blot analysis and ELISA we investigated variations in the transcription and protein levels of pfhrp2, pfhrp3 and PfHRP respectively in the different parasite lines, over the parasite intraerythrocytic life cycle. RESULTS: Transcription of pfhrp2 and pfhrp3 in different parasite lines over the parasite life cycle was observed to vary relative to the control parasite K1. In some parasite lines very low transcription of these genes was observed. The peak transcription was observed in ring-stage parasites. Pfhrp2 transcription was observed to be consistently higher than pfhrp3 transcription within parasite lines. The intraerythrocytic lifecycle stage at which the peak level of protein was present varied across strains. Total protein levels were more constant relative to total mRNA transcription, however a maximum 24 fold difference in expression at ring-stage parasites relative to the K1 strain was observed. CONCLUSIONS: The levels of transcription of pfhrp2 and pfhrp3, and protein expression of PfHRP varied between different P. falciparum strains. This variation may impact on the detection sensitivity of PfHRP2-detecting RDTs.

Ring Avulsion Injuries: A Systematic Review.

Science.gov (United States)

Bamba, Ravinder; Malhotra, Gautam; Bueno, Reuben A; Thayer, Wesley P; Shack, R Bruce

2018-01-01

Ring avulsion injuries can range from soft tissue injury to complete amputation. Grading systems have been developed to guide treatment, but there is controversy with high-grade injuries. Traditionally, advanced ring injuries have been treated with completion amputation, but there is evidence that severe ring injuries can be salvaged. The purpose of this systematic review was to pool the current published data on ring injuries. A systematic review of the English literature published from 1980 to 2015 in PubMed and MEDLINE databases was conducted to identify patients who underwent treatment for ring avulsion injuries. Twenty studies of ring avulsion injuries met the inclusion criteria. There were a total of 572 patients reported with ring avulsion injuries. The Urbaniak class breakdown was class I (54 patients), class II (204 patients), and class III (314 patients). The average total arc of motion (TAM) for patients with a class I injury was 201.25 (n = 40). The average 2-point discrimination was 5.6 (n = 10). The average TAM for patients with a class II injury undergoing microsurgical revascularization was 187.0 (n = 114), and the average 2-point discrimination was 8.3 (n = 40). The average TAM for patients with a class III injury undergoing microsurgical revascularization was 168.2 (n = 170), and the average 2-point discrimination was 10.5 (n = 97). Ring avulsion injuries are commonly classified with the Urbaniak class system. Outcomes are superior for class I and II injuries, and there are select class III injuries that can be treated with replantation. Shared decision making with patients is imperative to determine whether replantation is appropriate.

Investigation of piston ring – cylinder liner dry wear using a block-on-ring test rig

DEFF Research Database (Denmark)

Bihlet, Uffe; Klit, Peder; Felter, Christian L.

Characterization of the wear of piston rings and cylinder liner is an important aspect of large two stroke diesel engine design. Two major wear mechanisms exist; corrosive wear and mechanical wear. This paper deals with the most aggressive form of the latter, which is known as scuffing. Different...... that ceramic coating on the piston ring decreases the dry wear rate of both piston ring and liner, while the coefficient of friction is increased....

Simulations of a single vortex ring using an unbounded, regularized particle-mesh based vortex method

DEFF Research Database (Denmark)

Hejlesen, Mads Mølholm; Spietz, Henrik J.; Walther, Jens Honore

2014-01-01

, unbounded particle-mesh based vortex method is used to simulate the instability, transition to turbulence and eventual destruction of a single vortex ring. From the simulation data a novel method on analyzing the dynamics of the enstrophy is presented based on the alignment of the vorticity vector...... with the principal axis of the strain rate tensor. We find that the dynamics of the enstrophy density is dominated by the local flow deformation and axis of rotation, which is used to infer some concrete tendencies related to the topology of the vorticity field....

Novel Fiber-Optic Ring Acoustic Emission Sensor.

Science.gov (United States)

Wei, Peng; Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

2018-01-13

Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

Nilradicals of skew Hurwitz series of rings

Directory of Open Access Journals (Sweden)

Morteza Ahmadi

2015-05-01

Full Text Available ‎For a ring endomorphism α of a ring R, ‎Krempa called α a rigid endomorphism if aα(a=0 implies a = 0 for a in R. ‎A ring R is called rigid if there exists a rigid endomorphism of R. ‎In this paper‎, ‎we extend the α-rigid property of a ring R to the upper nilradical N_r(R of R. ‎For an endomorphism α and the upper nilradical N_r(R of a ring R, ‎we introduce the condition (*: ‎N_r(R is a α-ideal of R and aα(a in N_r(R implies a in N_r(R for a in R. ‎We study characterizations of a ring R with an endomorphism α satisfying the condition (*, ‎and we investigate their related properties‎. ‎The connections between the upper nilradical of R and the upper nilradical of the skew Hurwitz series ring (HR,α of R are also investigated‎.

Spin transitions in semiconductor quantum rings

International Nuclear Information System (INIS)

Baxevanis, Benjamin; Pfannkuche, Daniela

2010-01-01

We adopt the path integral Monte Carlo method to accurately resolve the total spin of the ground state of electrons confined in a quantum ring with different geometries. Using this method, an evaluation of the ground state of three electrons in a ring shows a spin transition to the fully polarized state by increasing the radius and thereby enhancing the Coulomb interaction. The total spin of the ground state is determined by the mutual interplay of confinement and electron-electron interaction. An analysis of the four-electron ring demonstrates that in this case no spin transitions take place. Furthermore, the effect of geometric distortion of the ring on its ground state has been investigated. Elliptically deforming the ring breaks the symmetry of the system and leads to the removal of orbital degeneracy. For strong distortion the splitting between hybridized states is sufficient to overcome the exchange-energy saving associated with a higher spin state. We have found that this effect removes the polarization of three electrons. Even in a four-electron ring the ground state is forced by the distortion to be unpolarized and thus suppressing the Hund's rule ground state.

Control of ring lasers by means of coupled cavities

DEFF Research Database (Denmark)

Buchhave, Preben; Abitan, Haim; Tidemand-Lichtenberg, Peter

2000-01-01

Variable phase coupling to an external ring is used to control a unidirectional ring laser. The observed behavior of the coupled rings is explained theoretically. We have found experimentally that by quickly changing the phase of the feedback from the external ring it is possible to Q......-switch the ring laser. Also, at certain values of the phase of the feedback in the external ring, instabilities in the total system occur and oscillations arise in the ring laser....

Moving-ring field-reversed mirror reactor

International Nuclear Information System (INIS)

Smith, A.C. Jr.; Ashworth, C.P.; Abreu, K.E.

1981-01-01

We describe a first prototype fusion reactor design of the Moving-Ring Field-Reversed Mirror Reactor. The fusion fuel is confined in current-carrying rings of magnetically-field-reversed plasma. The plamsa rings, formed by a coaxial plasma gun, are magnetically compressed to ignition temperature while they are being injected into the reactor's burner section. DT ice pellets refuel the rings during the burn at a rate which maintains constant fusion power. A steady train of plasma rings moves at constant speed through the reactor under the influence of a slightly diverging magnetic field. The aluminum first wall and breeding zone structure minimize induced radioactivity; hands-on maintenance is possible on reactor components outside the breeding blanket. Helium removes the heat from the Li 2 O tritium breeding blanket and is used to generate steam. The reactor produces a constant, net power of 376 MW

Artificial light harvesting by dimerized Möbius ring

Science.gov (United States)

Xu, Lei; Gong, Z. R.; Tao, Ming-Jie; Ai, Qing

2018-04-01

We theoretically study artificial light harvesting by a Möbius ring. When the donors in the ring are dimerized, the energies of the donor ring are split into two subbands. Because of the nontrivial Möbius boundary condition, both the photon and acceptor are coupled to all collective-excitation modes in the donor ring. Therefore, the quantum dynamics in the light harvesting is subtly influenced by dimerization in the Möbius ring. It is discovered that energy transfer is more efficient in a dimerized ring than that in an equally spaced ring. This discovery is also confirmed by a calculation with the perturbation theory, which is equivalent to the Wigner-Weisskopf approximation. Our findings may be beneficial to the optimal design of artificial light harvesting.

ring system

African Journals Online (AJOL)

1,3,2-DIAZABORACYCLOALKANE. RING SYSTEM. Negussie Retta" and Robert H. Neilson. 'Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. Department of Chemistry, Texas Christian University.

Ring cavity for a Raman capillary waveguide amplifier

Science.gov (United States)

Kurnit, N.A.

1981-01-27

A regenerative ring amplifier and regenerative ring oscillator are described which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplified Stokes signal is synchronous with the mode-locked spikes of the incoming CO/sub 2/ laser pump signal.

Ring cavity for a Raman capillary waveguide amplifir

Science.gov (United States)

Kurnit, N.A.

1981-01-27

A regenerative ring amplifier and regenerative ring oscillator are described which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplified Stokes signal is synchronous with the mode-locked spikes of the incoming CO/sub 2/ laser pump signal.

Experimental Study of Shock Generated Compressible Vortex Ring

Science.gov (United States)

Das, Debopam; Arakeri, Jaywant H.; Krothapalli, Anjaneyulu

2000-11-01

Formation of a compressible vortex ring and generation of sound associated with it is studied experimentally. Impulse of a shock wave is used to generate a vortex ring from the open end of a shock-tube. Vortex ring formation process has been studied in details using particle image Velocimetry (PIV). As the shock wave exits the tube it diffracts and expands. A circular vortex sheet forms at the edge and rolls up into a vortex ring. Far field microphone measurement shows that the acoustic pressure consists of a spike due to shock wave followed by a low frequency pressure wave of decaying nature, superimposed with high frequency pressure wave. Acoustic waves consist of waves due to expansion, waves formed in the tube during diaphragm breakage and waves associated with the vortex ring and shear-layer vortices. Unsteady evolution of the vortex ring and shear-layer vortices in the jet behind the ring is studied by measuring the velocity field using PIV. Corresponding vorticity field, circulation around the vortex core and growth rate of the vortex core is calculated from the measured velocity field. The velocity field in a compressible vortex ring differs from that of an incompressible ring due to the contribution from both shock and vortex ring.

-NH-dansyl isocolchicine exhibits a significantly improved tubulin-binding affinity and microtubule inhibition in comparison to isocolchicine by binding tubulin through its A and B rings.

Science.gov (United States)

Das, Lalita; Datta, Ajit B; Gupta, Suvroma; Poddar, Asim; Sengupta, Suparna; Janik, Mark E; Bhattacharyya, Bhabatarak

2005-03-08

Structure-activity relationship studies have established that the A and C rings of colchicine comprise the minimum structural feature necessary for high affinity drug-tubulin binding. Thus, colchicine acts as a bifunctional ligand by making two points of attachment to the protein. Furthermore, analogues belonging to the iso series of colchicine are virtually inactive in binding to tubulin and inhibiting microtubule assembly. In the present study, we found that the substitution of a hydrophobic dansyl group on the B-ring side chain (C7 position) of isocolchicine reverses the structural alterations at the C ring and the newly synthesized -NH-dansyl isocolchicine restores the lost biological activity of the compound. It inhibits microtubule assembly efficiently with an IC(50) value of 10 microM and competes with [(3)H]colchicine for binding to tubulin. Moreover, although -NH-dansyl colchicine binding to tubulin involves two steps, the -NH-dansyl isocolchicine-tubulin interaction has been found to occur via a one-step process. Also, the affinity constant of the -NH-dansyl isocolchicine-tubulin interaction is roughly only 3 times lower than that of the -NH-dansyl colchicine-tubulin interaction. These results suggest that the enhanced microtubule inhibitory ability of -NH-dansyl isocolchicine is therefore related to the affinity of the drug-tubulin interaction and not to any conformational changes upon binding tubulin. We also observed that the competition of -NH-dansyl isocolchicine with [(3)H]colchicine for binding to tubulin was dependent on the tubulin concentration. In conclusion, this paper for the first time indicates that a biologically active bifuntional colchicine analogue can be designed where the drug binds tubulin through its A and B rings, while the C ring remains inactive.

[Liesegang's rings resembling helminthiasis].

Science.gov (United States)

Zámecník, M; Riedl, I

1996-12-01

So called Liesegang's rings are lamellar corpuscles which develop after periodical precipitation of oversaturated solutions in gel medium. They can occur in cysts, closed cavities, inflammatory exudates and necroses. They resemble parasitic eggs, larvae or adult forms. A case of 28-year-old woman is presented with many Liesegang's rings in a stuff from dilated renal calyx. Their preliminary evaluation considered helminths, especially Dioctophyma renale.

Synlig læring

DEFF Research Database (Denmark)

Brandsen, Mads

2017-01-01

Introduktionen af John Hatties synlig læring i den danske skoleverden møder stadig meget kritik. Mange lærere og pædagoger oplever synlig læring som en tornado, der vil opsuge og ødelægge deres særlige danske udgave af den kontinentale dannelsestænkning, didaktik og pædagogik. Spørgsmålet er om...

How Jupiter's Ring Was Discovered.

Science.gov (United States)

Elliot, James; Kerr, Richard

1985-01-01

"Rings" (by astronomer James Elliot and science writer Richard Kerr) is a nontechnical book about the discovery and exploration of ring systems from the time of Galileo to the era of the Voyager spacecraft. One of this book's chapters is presented. (JN)

The Centaur Chariklo and its rings system from stellar occultations in 2017

Science.gov (United States)

Leiva, Rodrigo; Sicardy, Bruno; Camargo, Julio; Ortiz, Jose Luis; Berard, Diane; Desmars, Josselin; Chariklo Occultations Team; Rio Group; Lucky Star Occultation Team; Granada Occultation Team

2017-10-01

A stellar occultation in June 3, 2013 revealed the presence of a dense ring system around the Centaur object (10199) Chariklo (Braga-Ribas et al., Nature 2014). Subsequent analysis of occultation data and long-term photometric variations indicate that Chariklo's body is elongated (Leiva et al. 2017, submitted) and that the main ring exhibits significant longitudinal variations of the radial width (Bérard et al. 2017, in press). We report three multi-chord high-quality stellar occultation by Chariklo on April 9, 2017 and June 22, 2017 from Namibia, and July 23 2017 from South America. The analysis of this new data set is underway, but preliminary results are consistent with triaxial ellipsoidal models. From this analysis we will:-present refined models for the size and shape of Chariklo's main body andevaluate the heights and slopes of its topographic features.-give constraints on the longitudinal width variations of Chariklo's rings andexplore the possibility to obtain the rings apsidal precession rate.Chariklo's shape and topography have strong consequences on the dynamics of the rings through Lindblad-type resonances between mean motion of the ring particles and the spin of the main body, while the rings precession rate gives constraints on the dynamical oblateness of the main body.**Part of the research leading to these results has received funding from the European Research Council under the European Community’s H2020 (2014-2020/ ERC Grant Agreement n 669416 ”LUCKY STAR”).

Adiabatic compression of ion rings

International Nuclear Information System (INIS)

Larrabee, D.A.; Lovelace, R.V.

1982-01-01

A study has been made of the compression of collisionless ion rings in an increasing external magnetic field, B/sub e/ = zB/sub e/(t), by numerically implementing a previously developed kinetic theory of ring compression. The theory is general in that there is no limitation on the ring geometry or the compression ratio, lambdaequivalentB/sub e/ (final)/B/sub e/ (initial)> or =1. However, the motion of a single particle in an equilibrium is assumed to be completely characterized by its energy H and canonical angular momentum P/sub theta/ with the absence of a third constant of the motion. The present computational work assumes that plasma currents are negligible, as is appropriate for a low-temperature collisional plasma. For a variety of initial ring geometries and initial distribution functions (having a single value of P/sub theta/), it is found that the parameters for ''fat'', small aspect ratio rings follow general scaling laws over a large range of compression ratios, 1 3 : The ring radius varies as lambda/sup -1/2/; the average single particle energy as lambda/sup 0.72/; the root mean square energy spread as lambda/sup 1.1/; and the total current as lambda/sup 0.79/. The field reversal parameter is found to saturate at values typically between 2 and 3. For large compression ratios the current density is found to ''hollow out''. This hollowing tends to improve the interchange stability of an embedded low β plasma. The implications of these scaling laws for fusion reactor systems are discussed

Isolation and partial characterization of pigment-like antibiotics produced by a new strain of Streptosporangium isolated from an Algerian soil.

Science.gov (United States)

Boudjella, H; Bouti, K; Zitouni, A; Mathieu, F; Lebrihi, A; Sabaou, N

2007-07-01

Identification of a new actinomycete strain Sg3, belonging to the genus Streptosporangium and partial characterization of the produced antibacterial activities. The strain Sg3 was isolated from an Algerian Saharan soil and identified by morphological, chemotaxonomic and phylogenetic analyses to the genus Streptosporangium. The comparison of its physiological characteristics with those of known species of Streptosporangium showed significant differences with the nearest species Streptosporangium carneum. Analysis of the 16S rDNA sequence of strain Sg3 showed a similarity level ranging between 97% and 98.8% within Streptosporangium species, with S. carneum the most closely related. Strain Sg3 showed a red coloured antibacterial activity against gram-positive bacteria on several culture media. The purification of the red pigment by chromatographic methods led to the isolation of three active products. The (1)H nuclear magnetic resonance (NMR), mass, infrared (IR) and ultraviolet-visible (UV-VIS) data of these molecules strongly suggested that they belonged to the quinone-anthracycline group with three or more rings. Strain Sg3 represents a distinct phyletic line suggesting a new genomic species. It produces antibacterial activities identified as quinone-anthracycline aromatics. The quinone-anthracycline antibiotics are known for their antimicrobial and antineoplastic activities and are used in chemotherapy for the treatment of many cancer diseases. The present work constitutes the first stage of a whole series of studies to be realized on these antibiotics before arriving at a possible application.

Vortex Ring Interaction With a Coaxially Aligned Cylinderical Rod

Science.gov (United States)

Arakeri, Jaywant H.; Rajmanoharan, P.; Koochesfahani, Manoochehr

1998-11-01

We present results of experiments of a fully developed vortex ring interacting with a cylinderical rod, having a rounded nose, placed coaxially in line with the motion of the ring. The pressure field of the translating ring causes unsteady boundary layer separation and results in the formation of one or more ( secondary ) vortex rings, that subsequently interact. The nature and strength of the interaction depends on the ratio of the cylinder diameter to the ring diameter. For the larger diameter cylinders the vortex ring travels a few ring diameters before it breaks up. For the smaller diameter cylinders the vortex ring speed decreases slowly and, simultaneously, its diameter increases.

A study of the outermost ring of Saturn

International Nuclear Information System (INIS)

Bobrov, M.S.

1974-01-01

The attention is called to the fact that the discovery by Feibelman (1967) of the rarefied outer ring of Saturn is confirmed by the observations of Kuiper (1972). It is proposed to designate this object as E-ring (exterior) in order to avoid confusion with the innermost, also rarefied, D-ring observed by Guerin (1970) and earlier by Barabashov and Semejkin (1933). The effects of the interaction of E-ring with inner Saturn's satellites are briefly discussed. The conclusion is drawn that in cosmogonic time scale these effects are small. It is also shown that the optical thickness of E-ring is lower than 1/20000; the available photometric estimations of the geometric thickness of A- and B-rings need not be corrected for the light scattering and absorption by E-ring. (Auth.)

Cytoplasmic tethering of a RING protein RBCK1 by its splice variant lacking the RING domain

International Nuclear Information System (INIS)

Yoshimoto, Nobuo; Tatematsu, Kenji; Koyanagi, Tomoyoshi; Okajima, Toshihide; Tanizawa, Katsuyuki; Kuroda, Shun'ichi

2005-01-01

RBCC protein interacting with PKC 1 (RBCK1) is a transcription factor belonging to the RING-IBR protein family and has been shown to shuttle between the nucleus and cytoplasm, possessing both the nuclear export and localization signals within its amino acid sequence. RBCK2, lacking the C-terminal half of RBCK1 including the RING-IBR domain, has also been identified as an alternative splice variant of RBCK1. RBCK2 shows no transcriptional activity and instead it represses the transcriptional activity of RBCK1. Here, we show that RBCK2 is present usually in the cytoplasm containing two Leu-rich regions that presumably serve as a nuclear export signal (NES). Moreover, an NES-disrupted RBCK1 that is mostly localized within the nucleus is translocated to the cytoplasm when coexpressed with RBCK2, suggesting that RBCK2 serves as a cytoplasmic tethering protein for RBCK1. We propose a novel and general function of RING-lacking splice variants of RING proteins to control the intracellular localization and functions of the parental RING proteins by forming a hetero-oligomeric complex

Short Communication: Significance for pasture production in the ...

African Journals Online (AJOL)

Short Communication: Significance for pasture production in the southern Cape coastal region of naturalized rhizobia nodulating the strain specific Medicago ... The significance of naturalized strains of M. polymorpha in the production of medic pastures in some soils of the southern Cape coastal region is discussed.

Gravitoelectrodynamics in Saturn's F ring: encounters with Prometheus and Pandora

International Nuclear Information System (INIS)

Matthews, Lorin Swint; Hyde, Truell W

2003-01-01

The dynamics of Saturn's F ring have been a matter of curiosity ever since Voyagers 1 and 2 sent back pictures of the ring's unusual features. Some of these images showed three distinct ringlets with the outer two displaying a kinked and braided appearance. Many models have been proposed to explain the braiding seen in these images; most of these invoke perturbations caused by the shepherding moons or kilometre-sized moonlets embedded in the ring and are purely gravitational in nature. These models also assume that the plasma densities and charges on the grains are small enough that electromagnetic forces can be ignored. However, Saturn's magnetic field exerts a significant perturbative force on even weakly charged micron- and submicron-sized grains causing the grains to travel in epicyclic orbits about a guiding centre. This study examines the effect of Saturn's magnetic field on the dynamics of micron-sized grains along with gravitational interactions between the F ring's shepherding moons, Prometheus and Pandora. Due to the differences in charge-to-mass ratios of the various sized grains, a phase difference between different size populations is observed in the wavy orbits imposed by passage of the shepherding moons

Minimizing guard ring dead space in silicon detectors with an n-type guard ring at the edge of the detector

International Nuclear Information System (INIS)

Palviainen, Tanja; Tuuva, Tuure; Leinonen, Kari

2007-01-01

Detectors with n-type silicon with an n + -type guard ring were investigated. In the present work, a new p + /n/n + detector structure with an n + guard ring is described. The guard ring is placed at the edge of the detector. The detector depletion region extends also sideways, allowing for signal collection very close to the n-guard ring. In this kind of detector structure, the dead space of the detector is minimized to be only below the guard ring. This is proved by simulations done using Silvaco/ATLAS software

Minimizing guard ring dead space in silicon detectors with an n-type guard ring at the edge of the detector

Energy Technology Data Exchange (ETDEWEB)

Palviainen, Tanja [Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta (Finland)]. E-mail: tanja.palviainen@lut.fi; Tuuva, Tuure [Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta (Finland); Leinonen, Kari [Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta (Finland)

2007-04-01

Detectors with n-type silicon with an n{sup +}-type guard ring were investigated. In the present work, a new p{sup +}/n/n{sup +} detector structure with an n{sup +} guard ring is described. The guard ring is placed at the edge of the detector. The detector depletion region extends also sideways, allowing for signal collection very close to the n-guard ring. In this kind of detector structure, the dead space of the detector is minimized to be only below the guard ring. This is proved by simulations done using Silvaco/ATLAS software.

Soft Congruence Relations over Rings

Science.gov (United States)

Xin, Xiaolong; Li, Wenting

2014-01-01

Molodtsov introduced the concept of soft sets, which can be seen as a new mathematical tool for dealing with uncertainty. In this paper, we initiate the study of soft congruence relations by using the soft set theory. The notions of soft quotient rings, generalized soft ideals and generalized soft quotient rings, are introduced, and several related properties are investigated. Also, we obtain a one-to-one correspondence between soft congruence relations and idealistic soft rings and a one-to-one correspondence between soft congruence relations and soft ideals. In particular, the first, second, and third soft isomorphism theorems are established, respectively. PMID:24949493

Distributively generated matrix near rings

International Nuclear Information System (INIS)

Abbasi, S.J.

1993-04-01

It is known that if R is a near ring with identity then (I,+) is abelian if (I + ,+) is abelian and (I,+) is abelian if (I*,+) is abelian [S.J. Abbasi, J.D.P. Meldrum, 1991]. This paper extends these results. We show that if R is a distributively generated near ring with identity then (I,+) is included in Z(R), the center of R, if (I + ,+) is included in Z(M n (R)), the center of matrix near ring M n (R). Furthermore (I,+) is included in Z(R) if (I*,+) is included in Z(M n (R)). (author). 5 refs

Storage rings, internal targets and PEP

International Nuclear Information System (INIS)

Spencer, J.E.

1986-11-01

Storage rings with internal targets are described, using PEP as an example. The difference between electrons and heavier particles such as protons, antiprotons, and heavy ions is also discussed because it raises possibilities of bypass insertions for more exotic experiments. PEP is compared to other rings in various contexts to verify the assertion that it is an ideal ring for many fundamental and practical applications that can be carried on simultaneously

Plastic strain induced damage evolution and martensitic transformation in ductile materials at cryogenic temperatures

International Nuclear Information System (INIS)

Garion, C.; Skoczen, B.T.

2002-01-01

The Fe-Cr-Ni stainless steels are well known for their ductile behavior at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of these irreversible phenomena, associated with the dissipation of plastic power, are included into the constitutive model of stainless steels at cryogenic temperatures. The model is tested on the thin-walled corrugated shells (known as bellows expansion joints) used in the interconnections of the Large Hadron Collider, the new proton storage ring being constructed at present at CERN

The mobility of nitrogen across tree-rings of Norway spruce (Picea abies L.) and the effect of extraction method on tree-ring δ¹⁵N and δ¹³C values.

Science.gov (United States)

Tomlinson, G; Siegwolf, R T W; Buchmann, N; Schleppi, P; Waldner, P; Weber, P

2014-06-15

The use of stable nitrogen (N) isotope ratios (δ(15)N values) in dendroecological studies is often preceded by an extraction procedure using organic solvents to remove mobile N compounds from tree-rings. Although these mobile N compounds may be capable of distorting potential environmental signals in the tree-ring δ(15)N values, recent investigations question the necessity of such an extraction. We used an on-going experiment with simulated elevated N deposition previously labelled with (15)N, in conjunction with control trees, to investigate the necessity of extracting mobile N compounds (using a rapid extraction procedure) for tree-ring δ(15)N and δ(13)C studies, as well as N and C concentration analyses. In addition, we examined the magnitude of radial redistribution of N across tree-rings of Norway spruce (Picea abies). The (15)N label, applied in 1995/96, was found in tree-rings as far back as 1951, although the increased N availability did not cause any significant relative increase in tree growth. The rapid extraction procedure had no significant effect on tree-ring δ(15)N or δ(13)C values in either labelled or control trees, or on N concentration. The C concentrations, however, were significantly higher after extraction in control samples, with the opposite effect observed in labelled samples. Our results indicate that the extraction of mobile N compounds through the rapid extraction procedure is not necessary prior to the determination of Norway spruce δ(15)N or δ(13)C values in dendrochemical studies. δ(15)N values, however, must be interpreted with great care, particularly when used as a proxy for the N status of trees, due to the very high mobility of N within the tree stem sapwood of Norway spruce over several decades. Copyright © 2014 John Wiley & Sons, Ltd.

Novel Fiber-Optic Ring Acoustic Emission Sensor

Directory of Open Access Journals (Sweden)

Peng Wei

2018-01-01

Full Text Available Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

The rings of Uranus

Science.gov (United States)

Elliot, J. L.; Dunham, E.; Mink, D.

1977-01-01

A description is given of the observation of five brief occultations of the star SAO 158687 which occurred both before and after its occultation by Uranus on March 10, 1977. The events were observed with a three-channel occultation photometer, attached to a 91-cm telescope. The observations indicate that at least five rings encircle the planet Uranus. Possible reasons for the narrowness of the Uranus rings are discussed.

Vortex Ring Interaction with a Heated Screen

Science.gov (United States)

Smith, Jason; Krueger, Paul S.

2008-11-01

Previous examinations of vortex rings impinging on porous screens has shown the reformation of the vortex ring with a lower velocity after passing through the screen, the creation of secondary vortices, and mixing. A heated screen could, in principle, alter the vortex-screen interaction by changing the local liquid viscosity and density. In the present investigation, a mechanical piston-cylinder vortex ring generator was used to create vortex rings in an aqueous sucrose solution. The rings impinged on a screen of horizontal wires that were heated using electrical current. The flow was visualized with food color and video imaging. Tests with and without heat were conducted at a piston stroke-to-jet diameter ratio of 4 and a jet Reynolds number (Re) of 1000. The vortex rings slowed after passing through the screen, but in tests with heat, they maintained a higher fraction of their before-screen velocity due to reduction in fluid viscosity near the wires. In addition, small ``fingers'' that developed on the front of the vortex rings as they passed through the screen exhibited positive buoyancy effects in the heated case.

Ring-opening polymerization of 19-electron [2]cobaltocenophanes: a route to high-molecular-weight, water-soluble polycobaltocenium polyelectrolytes.

Science.gov (United States)

Mayer, Ulrich F J; Gilroy, Joe B; O'Hare, Dermot; Manners, Ian

2009-08-05

Water-soluble, high-molecular-weight polycobaltocenium polyelectrolytes have been prepared by ring-opening polymerization (ROP) techniques. Anionic polymerization of a strained 19-electron dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium chloride resulted in the formation of oligomers with up to nine repeat units. Thermal ROP of dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium nitrate resulted in the formation of high-molecular-weight polycobaltocenium nitrate, a redox-active cobalt-containing polyelectrolyte.

Achieving Translationally Invariant Trapped Ion Rings

Science.gov (United States)

Urban, Erik; Li, Hao-Kun; Noel, Crystal; Hemmerling, Boerge; Zhang, Xiang; Haeffner, Hartmut

2017-04-01

We present the design and implementation of a novel surface ion trap design in a ring configuration. By eliminating the need for wire bonds through the use of electrical vias and using a rotationally invariant electrode configuration, we have realized a trap that is able to trap up to 20 ions in a ring geometry 45um in diameter, 400um above the trap surface. This large trapping height to ring diameter ratio allows for global addressing of the ring with both lasers and electric fields in the chamber, thereby increasing our ability to control the ring as a whole. Applying compensating electric fields, we measure very low tangential trap frequencies (less than 20kHz) corresponding to rotational barriers down to 4mK. This measurement is currently limited by the temperature of the ions but extrapolation indicates the barrier can be reduced much further with more advanced cooling techniques. Finally, we show that we are able to reduce this energy barrier sufficiently such that the ions are able to overcome it either through thermal motion or rotational motion and delocalize over the full extent of the ring. This work was funded by the Keck Foundation and the NSF.

On Learning Ring-Sum-Expansions

DEFF Research Database (Denmark)

Fischer, Paul; Simon, H. -U.

1992-01-01

The problem of learning ring-sum-expansions from examples is studied. Ring-sum-expansions (RSE) are representations of Boolean functions over the base {#123;small infinum, (+), 1}#125;, which reflect arithmetic operations in GF(2). k-RSE is the class of ring-sum-expansions containing only monomials...... of length at most k:. term-RSE is the class of ring-sum-expansions having at most I: monomials. It is shown that k-RSE, k>or=1, is learnable while k-term-RSE, k>2, is not learnable if RPnot=NP. Without using a complexity-theoretical hypothesis, it is proven that k-RSE, k>or=1, and k-term-RSE, k>or=2 cannot...... be learned from positive (negative) examples alone. However, if the restriction that the hypothesis which is output by the learning algorithm is also a k-RSE is suspended, then k-RSE is learnable from positive (negative) examples only. Moreover, it is proved that 2-term-RSE is learnable by a conjunction...

Computerspil og læring

Directory of Open Access Journals (Sweden)

Lasse Juel Larsen

2015-02-01

Full Text Available Game-based learning og gamification er ord, der ofte optræder i forbindelse med computerspil og læring. Denne artikel vil analytisk undersøge, hvordan computerspil og læring går i forbindelse med hinanden. Artikel tager afsæt i Gregory Batesons læringsteori og læser denne igennem det kommercielle computerspil StarCraft 2 fra Blizzard Intertainment. Batesons læringsteori vil ikke alene blive gennemgået, men også udvidet og perspektiveret.  Formålet med denne indsats er at skabe et afsæt, der kan demonstrere, hvordan læring foregår i computerspil. Herefter vil afsættet blive anvendt til at destillere et læringsteoretisk udkast. Artiklen falder således i to dele, hvor den første analytisk adresserer, hvordan læring i computerspil foregår, mens den anden er teoriproducerende på baggrund af resultaterne fra første del.

On rings generating supernilpotent and special atoms | France ...

African Journals Online (AJOL)

We study prime rings which generate supernilpotent (respectively special) atoms, that is, atoms of the lattice of all supernilpotent (respectively special) radicals. A prime ring A is called a **-ring if the smallest special class containing A is closed under semiprime homomorphic images of A. A semiprime ring A whose every ...

Effects of the Ring Current on ULF Waves in the Magnetosphere

Directory of Open Access Journals (Sweden)

Khan-Hyuk Kim

1994-06-01

Full Text Available A three-dimensional box model has been developed to study the MHD wave coupling in the magnetosphere. In this model, the effects of the ring current are included by assuming the pressure gradients in the MHD equations. It is found that the axisymmetric ring current may play an important role in producing spectral noises in compressional waves, while field line resonances have no such disturbances. These results may explain the current observational characteristics that compressional cavity modes hardly appear in the satellite experiment, while field line resonances often occur. Our numerical results also suggest that any discrete spectral peaks such as the global cavity modes can hardly occur where the pressure distribution of the ring current becomes important. The continuous band of transverse waves is found to be unperturbed until the ring current becomes significantly asymmetric with respect to the dipole axis. In addition, our results in the absence of the pressure gradient are found to be consistent with the previous results from the box-like and dipole models.

Lamb shift of energy levels in quantum rings

International Nuclear Information System (INIS)

Kryuchkyan, G Yu; Kyriienko, O; Shelykh, I A

2015-01-01

We study the vacuum radiative corrections to energy levels of a confined electron in quantum rings. The calculations are provided for the Lamb shift of energy levels in a low-momentum region of virtual photons and for both one-dimensional and two-dimensional quantum rings. We show that contrary to the well known case of a hydrogen atom the value of the Lamb shift increases with the magnetic momentum quantum number m. We also investigate the dependence of the Lamb shift on magnetic flux piercing the ring and demonstrate a presence of magnetic-flux-dependent oscillations. For a one-dimensional ring the value of the shift strongly depends on the radius of the ring. It is small for semiconductor rings but can attain measurable quantities in natural organic ring-shape molecules, such as benzene, cycloalcanes and porphyrins. (paper)

Phase behaviour of polyethylene knotted ring chains

International Nuclear Information System (INIS)

Wen Xiao-Hui; Xia A-Gen; Chen Hong-Ping; Zhang Lin-Xi

2011-01-01

The phase behaviour of polyethylene knotted ring chains is investigated by using molecular dynamics simulations. In this paper, we focus on the collapse of the polyethylene knotted ring chain, and also present the results of linear and ring chains for comparison. At high temperatures, a fully extensive knot structure is observed. The mean-square radius of gyration per bond (S 2 )/(Nb 2 ) and the shape factor (δ*) depend on not only the chain length but also the knot type. With temperature decreasing, chain collapse is observed, and the collapse temperature decreases with the chain length increasing. The actual collapse transition can be determined by the specific heat capacity C v , and the knotted ring chain undergoes gas—liquid—solid-like transition directly. The phase transition of a knotted ring chain is only one-stage collapse, which is different from the polyethylene linear and ring chains. This investigation can provide some insights into the statistical properties of knotted polymer chains. (condensed matter: structural, mechanical, and thermal properties)

Resource-saving technology for manufacturing billets for piston’s rings

Directory of Open Access Journals (Sweden)

A. N. Krutilin

2010-10-01

Full Text Available Piston’s rings are one of the most critical parts of heavy-duty engines for wear-work in conditions of prolonged exposure of alternating loads and high temperatures. Currently in the world production of billets for piston’s rings is dominated by the two methods of casting: production of individual and oiling billets of gray and ductile cast iron in green-sand mold and shell mold and centrifugal casting method (intended primarily for oiling billets of ductile iron; the technology for individual production billets for piston’s rings with a diameter up to 250 mm, from 250 to 450 mm with individual and oiling ways, over 450 mm - preference of oiling billet. The best parameters of physical-mechanical and operational characteristics piston’s rings are in the case of manufacture of billets to the maximum extent approaching the configuration to the finished product. The rings made of shaped billets are characterized by uniform distribution of properties from the perimeter, provide a given diagram of pressures and full fit to the cylinder. Because of deficiencies of traditional methods of casting, continuous quality requirements for billets, the need for economy of material, fuel and energy resources, are finding new progressive technological processes of production of high-quality billets for piston’s rings. One of the most promising for piston rings billet is a method of casting consists of immersing the sand molds into the melt. It is interesting idea, expressed by A. Sutherland and subsequently patented in several countries in the way of casting method, called "immersion pouring technology" (ICT-Immersion Casting Technique [1]. Experiments, conducted in the laboratory of the Belarusian National Technical University, have identified significant shortcomings of immersion method of casting. When forms are immersing, have an intensive gassing in molten metal, and freezing of the metal on the out surface of the form. But despite some

SXLS storage ring design

International Nuclear Information System (INIS)

Anon.

1991-01-01

X-ray lithography has emerged as a strong candidate to meet the demands of ever finer linewidths on integrated circuits, particularly for linewidths less than .25 microns. Proximity printing X-ray lithography makes use of soft X-rays to shadow print an image of a mask onto a semiconductor wafer to produce integrated circuits. To generate the required X-rays in sufficient quantities to make commercial production viable, electron storage rings have been proposed as the soft X-ray sources. Existing storage rings have been used to do the initial development work and the success of these efforts has led the lithographers to request that new rings be constructed that are dedicated to X-ray lithography. As a result of a series of workshops held at BNL [10.3] which were attended by both semiconductor and accelerator scientists, the following set of zeroth order specifications' on the light and electron beam of a storage ring for X-ray lithography were developed: critical wavelength of light: λ c = 6 to 10 angstroms, white light power: P = 0.25 to 2.5 watts/mrad, horizontal collection angle per port: θ = 10 to 50 mrad, electron beam sizes: σ x ∼ σ y y ' < 1 mrad

The Storage Ring Proton EDM Experiment

Science.gov (United States)

Semertzidis, Yannis; Storage Ring Proton EDM Collaboration

2014-09-01

The storage ring pEDM experiment utilizes an all-electric storage ring to store ~1011 longitudinally polarized protons simultaneously in clock-wise and counter-clock-wise directions for 103 seconds. The radial E-field acts on the proton EDM for the duration of the storage time to precess its spin in the vertical plane. The ring lattice is optimized to reduce intra-beam scattering, increase the statistical sensitivity and reduce the systematic errors of the method. The main systematic error is a net radial B-field integrated around the ring causing an EDM-like vertical spin precession. The counter-rotating beams sense this integrated field and are vertically shifted by an amount, which depends on the strength of the vertical focusing in the ring, thus creating a radial B-field. Modulating the vertical focusing at 10 kHz makes possible the detection of this radial B-field by a SQUID-magnetometer (SQUID-based BPM). For a total number of n SQUID-based BPMs distributed around the ring the effectiveness of the method is limited to the N = n /2 harmonic of the background radial B-field due to the Nyquist sampling theorem limit. This limitation establishes the requirement to reduce the maximum radial B-field to 0.1-1 nT everywhere around the ring by layers of mu-metal and aluminum vacuum tube. The metho's sensitivity is 10-29 e .cm , more than three orders of magnitude better than the present neutron EDM experimental limit, making it sensitive to SUSY-like new physics mass scale up to 300 TeV.

Antibacterial and Herbicidal Activity of Ring-Substituted 3-Hydroxynaphthalene-2-carboxanilides

Directory of Open Access Journals (Sweden)

Katarina Kralova

2013-07-01

Full Text Available In this study, a series of twenty-two ring-substituted 3-hydroxy-N-phenylnaphthalene-2-carboxanilides were prepared and characterized. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET in spinach (Spinacia oleracea L. chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four Staphylococcus strains and against two mycobacterial species. 3-Hydroxy-N-(2-methoxyphenylnaphthalene-2-carboxamide showed high biological activity (MIC = 55.0 µmol/L against S. aureus as well as methicillin-resistant strains. N-(2-Fluorophenyl-3-hydroxynaphthalene-2-carboxamide showed higher activity (MIC = 28.4 µmol/L against M. marinum than the standard isoniazid and 3-hydroxy-N-(4-nitrophenylnaphthalene-2-carboxamide expressed higher activity (MIC = 13.0 µmol/L against M. kansasii than the standard isoniazid. Cytotoxicity assay of effective antimicrobial compounds was performed using the human monocytic leukemia THP-1 cell line. The PET-inhibiting activity expressed by IC50 value of the most active compound 3-hydroxy-N-(3-nitrophenylnaphthalene-2-carboxamide was 16.9 μmol/L. The structure-activity relationships of all compounds are discussed.

Open-ring enhancement sign in diagnosing demyelinating pseudotumor

International Nuclear Information System (INIS)

Fang Liting; Wang Zhiping; Wang Linyou

2010-01-01

Objective: To describe open-ring enhancement sign on MRI of demyelinating pseudotumor. Methods: Contrast-enhanced MRI of histologically confirmed demyelinating pseudotumors (14 patients) and astrocytomas (21) was reviewed. Results: Of the 14 cases of demyelinating pseudotumor, open-ring enhancement pattern was observed in 6; closed ring enhancement in 2; nodular enhancement in 3; patchy enhancement in 1; slight enhancement in 1; and no enhancement in 1. Of the 21 cases of astrocytoma, there was complete ring or lace-like enhancement in 13, no contrast enhancement in 6, patchy enhancement in 2, and none with open-ring enhancement pattern. Conclusion: Open-ring enhancement is a valuable sign in differential diagnosis between demyelinating pseudotumor and astrocytoma. (authors)

21 CFR 870.3800 - Annuloplasty ring.

Science.gov (United States)

2010-04-01

...) Identification. An annuloplasty ring is a rigid or flexible ring implanted around the mitral or tricuspid heart valve for reconstructive treatment of valvular insufficiency. (b) Classification. Class II (special...

Strain preservation of experimental animals: vitrification of two-cell stage embryos for multiple mouse strains.

Science.gov (United States)

Eto, Tomoo; Takahashi, Riichi; Kamisako, Tsutomu

2015-04-01

Strain preservation of experimental animals is crucial for experimental reproducibility. Maintaining complete animal strains, however, is costly and there is a risk for genetic mutations as well as complete loss due to disasters or illness. Therefore, the development of effective vitrification techniques for cryopreservation of multiple experimental animal strains is important. We examined whether a vitrification method using cryoprotectant solutions, P10 and PEPeS, is suitable for preservation of multiple inbred and outbred mouse strains. First, we investigated whether our vitrification method using cryoprotectant solutions was suitable for two-cell stage mouse embryos. In vitro development of embryos exposed to the cryoprotectant solutions was similar to that of fresh controls. Further, the survival rate of the vitrified embryos was extremely high (98.1%). Next, we collected and vitrified two-cell stage embryos of 14 mouse strains. The average number of embryos obtained from one female was 7.3-33.3. The survival rate of vitrified embryos ranged from 92.8% to 99.1%, with no significant differences among mouse strains. In vivo development did not differ significantly between fresh controls and vitrified embryos of each strain. For strain preservation using cryopreserved embryos, two offspring for inbred lines and one offspring for outbred lines must be produced from two-cell stage embryos collected from one female. The expected number of surviving fetuses obtained from embryos collected from one female of either the inbred or outbred strains ranged from 2.9 to 19.5. The findings of the present study indicated that this vitrification method is suitable for strain preservation of multiple mouse strains. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Tree rings and radiocarbon calibration

International Nuclear Information System (INIS)

Barbetti, M.

1999-01-01

Only a few kinds of trees in Australia and Southeast Asia are known to have growth rings that are both distinct and annual. Those that do are therefore extremely important to climatic and isotope studies. In western Tasmania, extensive work with Huon pine (Lagarostrobos franklinii) has shown that many living trees are more than 1,000 years old, and that their ring widths are sensitive to temperature, rainfall and cloud cover (Buckley et al. 1997). At the Stanley River there is a forest of living (and recently felled) trees which we have sampled and measured. There are also thousands of subfossil Huon pine logs, buried at depths less than 5 metres in an area of floodplain extending over a distance of more than a kilometre with a width of tens of metres. Some of these logs have been buried for 50,000 years or more, but most of them belong to the period between 15,000 years and the present. In previous expeditions in the 1980s and 1990s, we excavated and sampled about 350 logs (Barbetti et al. 1995; Nanson et al. 1995). By measuring the ring-width patterns, and matching them between logs and living trees, we have constructed a tree-ring dated chronology from 571 BC to AD 1992. We have also built a 4254-ring floating chronology (placed by radiocarbon at ca. 3580 to 7830 years ago), and an earlier 1268-ring chronology (ca. 7,580 to 8,850 years ago). There are many individuals, or pairs of logs which match and together span several centuries, at 9,000 years ago and beyond

Sutureless anastomoses using magnetic rings in canine liver transplantation model.

Science.gov (United States)

Liu, Shi-Qi; Lei, Peng; Cui, Xiao-Hai; Lv, Yi; Li, Jian-Hui; Song, Yu-Long; Zhao, Ge

2013-12-01

anastomoses formed with magnetic rings. In group C, gross observation, histologic staining, and scanning electron microscopy were used to evaluate the vessels and bile ducts 12 wk postoperatively. In group A, the total operation time, inferior vena cava, and portal vein anastomosis times were significantly shortened, and the anhepatic phase was reduced to about one-fifth that of group B, which was a significant difference between the two groups (P anastomoses also healed well. The magnetic pinning-ring device offers a simple, fast, reliable, and efficacious technique for nonsuturing vascular and bile duct anastomoses. Use of this device shortens operation time, maintains a high patency rate, and improves the healing of tissue. Application of the magnetic ring anastomosis technique can effectively reduce the complications caused by hand suturing, and can reduce the extent of ischemia-reperfusion injury, leading to smoother operations and improved prognosis. Copyright © 2013 Elsevier Inc. All rights reserved.

Large diameter femoral heads impose significant alterations on the strains developed on femoral component and bone: a finite element analysis.

Science.gov (United States)

Theodorou, E G; Provatidis, C G; Babis, G C; Georgiou, C S; Megas, P D

2011-01-01

Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost's law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used.

Bimodality and the formation of Saturn's ring particles

International Nuclear Information System (INIS)

Gehrels, T.

1980-01-01

The F ring appears to have an outer and an inner rim, with only the latter observed by the imaging photopolarimeter (IPP) on the Pioneer Saturn spacecraft. The inside of the G ring, near 2.49 R/sub S/, may also be seen in the optical data. 1979S1 is red as well as dark. The light scattered through the B ring is noticeably red. The A ring has a dense outer rim. The Cassini Division and the French Division (Dollfus Division) have a dark gap near their centers. The C ring becomes weaker toward the center such that outer, middle, and inner C rings can be recognized. The Pioneer and earth-based observations are explained with a model for the B and A rings to some extent of a bimodal size distributions of particles; the larger ones may be original accretions, while small debris diffuses inward through the Cassini Division and the C ring. During the formation of the ring system, differential gravitation allowed only silicaceous grains of higher density (rho> or approx. =3 g cm -3 ) to coagulate. These serve as interstitial cores for snowy carbonaceous grains, between the times of accretion from interplanetary cometary grains and liberation by collision followed by diffusion inward to Saturn and final evaporation

Scalability analysis of the synchronizability for ring or chain networks with dense clusters

International Nuclear Information System (INIS)

Lu, Jun-An; Zhang, Yong; Chen, Juan; Lü, Jinhu

2014-01-01

It is well known that most real-world complex networks, such as the Internet and the World Wide Web, are evolving networks. An interesting fundamental question is: how do some important functions or dynamical behaviors of complex networks evolve with increasing network scale? This paper aims at investigating the scalability of the synchronizability for ring or chain networks with dense clusters as the network size increases. We discover some interesting phenomena as follows: (i) the synchronizability of ring or chain networks with clusters decreases with increasing network scale regardless of the inner structures of all communities; (ii) for the same network scale, the network synchronizability decreases more quickly with increasing number of cluster blocks than with increasing number of nodes within the cluster block; (iii) the number of rings or chains has a much more significant influence on the network synchronizability than the size of the rings or chains. Our results indicate that network synchronizability can be maintained with increasing network scale by avoiding ring and chain structures. (paper)

Mechanical seal having a double-tier mating ring

Science.gov (United States)

Khonsari, Michael M.; Somanchi, Anoop K.

2005-09-13

An apparatus and method to enhance the overall performance of mechanical seals in one of the following ways: by reducing seal face wear, by reducing the contact surface temperature, or by increasing the life span of mechanical seals. The apparatus is a mechanical seal (e.g., single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines) comprising a rotating ring and a double-tier mating ring. In a preferred embodiment, the double-tier mating ring comprises a first and a second stationary ring that together form an agitation-inducing, guided flow channel to allow for the removal of heat generated at the seal face of the mating ring by channeling a coolant entering the mating ring to a position adjacent to and in close proximity with the interior surface area of the seal face of the mating ring.

Polarized particles in storage rings

International Nuclear Information System (INIS)

Derbenev, Ya.S.; Kondratenko, A.M.; Serednyakov, S.I.; Skrinskij, A.N.; Tumajkin, G.M.; Shatunov, Yu.M.

1977-01-01

Experiments with polarized beams on the VEPP-2M and SPEAK storage rings are described. Possible methods of producing polarized particle beams in storage rings as well as method of polarization monitoring are counted. Considered are the processes of radiation polarization of electrons and positrons. It is shown, that to preserve radiation polarization the introduction of regions with a strong sign-variable magnetic field is recommended. Methods of polarization measurement are counted. It is suggested for high energies to use dependence of synchrotron radiation power on transverse polarization of electrons and positrons. Examples of using polarizability of colliding beams in storage rings are presented

Saturn Rings Origin: Quantum Trapping of Superconducting Iced Particles and Meissner Effect Lead to the Stable Rings System

Science.gov (United States)

Viktorovich Tchernyi, Vladimir

2018-06-01

Saturn Rings Origin: Quantum Trapping of Superconducting Iced Particles and Meissner Effect Lead to the Stable Rings System Vladimir V. Tchernyi (Cherny), Andrew Yu. Pospelov Modern Science Institute, SAIBR, Moscow, Russia. E-mail: chernyv@bk.ruAbstractIt is demonstrated how superconducting iced particles of the protoplanetary cloud of Saturn are coming to magnetic equator plane and create the stable enough rings disk. There are two steps. First, after appearance of the Saturn magnetic field due to Meissner phenomenon all particles orbits are moving to the magnetic equator plane. Finally they become distributed as rings and gaps like iron particles around magnet on laboratory table. And they are separated from each other by the magnetic field expelled from them. It takes up to few tens of thousands years with ten meters rings disk thickness. Second, due to their quantum trapping all particles become to be trapped within magnetic well at the magnetic equator plane due to Abrikosov vortex for superconductor. It works even when particles have small fraction of superconductor. During the rings evolution some contribution to the disk also could come from the collision-generated debris of the current moon and from the geysers like it happened due to magnetic coupling of Saturn and Enceladus. The rings are relict of the early days of the magnetic field of Saturn system.

On the evolution of vortex rings with swirl

International Nuclear Information System (INIS)

Naitoh, Takashi; Okura, Nobuyuki; Gotoh, Toshiyuki; Kato, Yusuke

2014-01-01

A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as “peeling off” appears. The amount of discharging fluid due to the “peeling off” increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the “peeling off” is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions

On the evolution of vortex rings with swirl

Energy Technology Data Exchange (ETDEWEB)

Naitoh, Takashi, E-mail: naitoh.takashi@nitech.ac.jp [Department of Engineering Physics, Electronics and Mechanics, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Okura, Nobuyuki, E-mail: ohkura@meijo-u.ac.jp [Department of Vehicle and Mechanical Engineering, Meijo University, 1-501 Shiogamaguchi Tempaku-ku, Nagoya 468-8502 (Japan); Gotoh, Toshiyuki, E-mail: gotoh.toshiyuki@nitech.ac.jp [Department of Scientific and Engineering Simulation, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Kato, Yusuke [Controller Business Unit Engineering Division 1, Engineering Department 3, Denso Wave Incorporated, 1 Yoshiike Kusagi Agui-cho, Chita-gun Aichi 470-2297 (Japan)

2014-06-15

A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as “peeling off” appears. The amount of discharging fluid due to the “peeling off” increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the “peeling off” is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions.